Tool for countersinking holes. Outline of educational practice on the topic "Reaming, countersinking and deployment"
In the process of manufacturing high-quality parts and products, one often has to deal with insufficient accuracy in making the required holes. To obtain the necessary parameters, a countersink is used.
Application and types of countersinks
A countersink is a multi-blade, multi-tooth cutting tool used to refine pre-made round holes in parts and workpieces made of different materials (pictured). Processing in this way is used to increase the diameter and obtain a better surface of the hole by cutting.
This process is called reaming. The cutting method is similar to the drilling procedure: the same rotation of the tool for countersinking around its axis and the simultaneous translational movement of the tool along the axis are observed.
We developed a countersink for the metalworking industry in order to process a drilled, slotted or punched hole. A metal drill, the requirements for the characteristics of which are regulated by GOST 12489-71, is used when performing intermediate or already final processing. In this regard, there are two types of tools:
- for subsequent deployment with an allowance;
- to obtain a high-precision hole - with a quality of H11 (tolerance of 4-5 accuracy classes).
You can get acquainted with the GOST requirements for countersinks by downloading the document in pdf format from the link below.
When boring is used, the diameter increases, surface accuracy and hole cleanliness increase. Reaming is intended mainly for:
- achieve a smoother, cleaner hole surface before reaming or threading;
- calibrating the hole for a bolt, stud or some other fastener.
Countersinks are used, the requirements for which are determined by GOST 12489-71, also when processing end surfaces and when performing certain operations that give the hole the desired profile (for example, expanding the recess in the upper part of the hole intended for bolt heads).
Countersinks are divided into several types according to the way they are fixed in the machine:
- mounted;
- tail (with a metric taper or with a Morse taper - types of shank for mounting in a machine).
By design, countersinks are of the following types:
- prefabricated;
- whole;
- welded;
- with carbide inserts.
A solid core drill is similar to a drill, so its second name is a drill bit. It has more than a simple drill, spiral flutes and cutting edges (3 to 6 teeth). The cutting part of the tool, as stipulated by GOST 12489-71, is made of P18, P9 or made with carbide inserts (BK4, BK6, BK8 for cast iron machining, T15K6 for steel machining). A tool equipped with carbide inserts has a higher productivity (higher cutting speed) than a tool made from high speed steel.
There is also a conical countersink (for processing surfaces of a conical configuration) and the so-called reverse type of countersinks.
Countersinking and related operations
Countersinking is similar to the reaming operation: both processes are carried out with a finished hole. The difference is that the reaming result is more accurate. During the operation, defects that occur after stamping, casting or drilling are eliminated. Such indicators as surface cleanliness, accuracy are improved, a high degree of concentricity is achieved.
Often, when forming holes with a drill (especially deep ones), a deviation from the center is observed due to the low rigidity of the tool. A countersink differs from a drill in that it has a higher rigidity due to the increased number of cutting teeth. It is important that this difference provides a more accurate direction of movement of the tool, and at a smaller depth of cut, high cleanliness is observed. When drilling holes, you can get qualities of 11–12, the surface roughness of the hole is Rz 20 micrometers. During the reaming operation, we obtain grades 9–11, roughness 2.5 micrometers.
An even more accurate operation is the deployment process (6-9th grade, Ra 1.25-0.25 micrometers). This is a fine cutting. Hole reaming is a semi-finishing operation. Countersinking and reaming holes, if both of these operations are provided for by the technological process, are performed in one installation of the part on the machine.
Often they confuse countersinking and countersinking of holes and incorrectly call another tool a countersink - a countersink (see photo below). Countersinks, unlike countersinks, have a different design and are used to solve other technological problems.
Countersinking is used in the process of chamfering the top of holes, as well as to obtain conical recesses. There is also a cylindrical countersink, but it is more correct to call such a tool a countersink. With the help of such a tool, recesses of the appropriate shape are obtained in the details. To perform such a countersink operation, a universal tool can also be used - a drill specially combined with a countersink.
After watching this video, you can easily understand the principle of operation and purpose of the countersink, as well as its difference from the countersink and other related holemaking tools.
In order not to get confused in similar operations, it is enough to consider and remember this diagram, which clearly explains the design differences and the purpose of tools for processing holes.
Metal reaming rules
At home, for countersinking recesses (for example, under the heads of bolts or for changing the diameter of a hole in a larger direction), a simple drill attached to an electric or even a hand drill is also suitable. On an industrial scale, reaming is an operation that requires considerable power and accuracy of the equipment used. That is why, in production conditions, to perform countersinking, as, in fact, countersinking, equipment is used:
- turning (most often);
- drilling (at least often);
- boring (often as one of the secondary operations);
- aggregate (as a secondary operation of an automated line);
- vertical or horizontal milling (rare).
In the process of processing a hole obtained in the product during its casting, it is advisable to first bore it with a cutter by about 5–10 millimeters in depth so that the countersink takes the correct initial direction.
When processing steel products, it is recommended to use cutting fluids. The process of reaming cast iron and non-ferrous metals does not require cooling. Proper selection of metal-cutting tools used for both countersinking and countersinking is a very important step. To do this, pay attention to certain factors:
- The type of tool is selected depending on the material of the part, the nature of the processing. The location of the hole, the seriality of the processes performed should also be taken into account.
- Based on the given depth, diameter, required processing accuracy, the size of the tool for countersinking and countersinking is selected.
- The design of the countersink and countersink is determined by the method of mounting the tool on the machine.
- The material of the tool for performing countersinking or countersinking operations depends on the material of the workpiece (for example, there are countersinks specifically for woodworking), the intensity of the operating mode and some other factors.
A drill is selected from reference books or guided by such a regulatory document as GOST 12489-71. The tool must meet certain technical conditions of use, which also stipulates GOST 12489-71.
- Products made of structural steel with holes up to 40 millimeters in diameter are processed with a countersink made of high-speed steel, having a diameter of 10-40 millimeters and 3-4 teeth, respectively.
- For products made of hard-to-cut and
Among the metalworking tools used to create holes, countersinks and countersinks deserve special attention. With their help, openings are made with specified characteristics, for example, the stability of important geometric parameters, roughness, narrowing of a cylindrical hole. Consider what a countersink and countersink are.
Terminology
A countersink is a multi-blade cutting tool used for making holes in metal parts. After processing, recesses of a conical / cylindrical type are obtained, it is possible to create a reference plane near the holes, chamfer the center hole.
Hole countersinking is a secondary preparation of finished holes for placing hardware heads - bolts, screws, rivets
Zenker - a cutting tool with a multi-blade surface. It is used in the machining of cylindrical/conical type holes in workpieces to expand the diameter, improve surface characteristics and accuracy. This type of processing is called reaming. This is a semi-finish cutting.
A - drilling with a drill B - boring on a lathe C - countersinking with a countersink D - reaming with a reamer E, F - countersinking with a countersink G - countersinking with a countersink H - threading with a tap
Hole countersinking is the process of cultivating the upper part of an opening in order, for example, to deburr the edge of a hole or create recesses to hide the head of a rivet or screw and level it with the surface of the part. The tool used for this task is called a countersink.
Types of countersinks and countersinks
The production of cutting tools for metal is subject to the main category of country standards (GOST) and technical regulations for the use of the finished product. On units with partial automated control, the following types of countersinks are used:
- Cylindrical, with diameters from 10 to 20 mm. This set of blades is produced with a coating of wear-resistant elements. GOST 12489-71 is regulated.
- Indivisible conical, from 10 to 40 mm. Manufactured from wear-resistant alloy steel. Subject to TU 2-035-923-83.
- Whole, in the form of nozzles, with a diameter of 32 to 80 mm. GOST 12489-71 is regulated.
- Conical or mounted, subject to GOST 3231-71. They are noted by the presence of special plates obtained from hard iron alloys.
A countersink is also a tool with numerous blades, but it has clear differences from a countersink in terms of use. These devices are divided into several types:
- Conical countersink. It has an operated head with a cone angular coefficient of 60.90, 120 degrees. It is mainly implemented for cultivating bases for fasteners and removing chamfers, that is, to blunt sharp edges. GOST 14953-80 E is regulated.
- Rounded countersink (cylindrical). The device can have a rounded or conical end, having a wear-resistant base coating. It is mainly implemented as processing of support bases.
What is a drill, systematization
A cutting tool for metal (drill bit) allows you to countersink an opening into parts up to the 5th group of accuracy. It is widely used for semi-finishing parts before mechanical reaming. By structure, it is divided into types:
- holistic;
- packed;
- tail;
- connected.
Externally, metal-cutting devices look like a simple small drill, but they have an increased number of cutting edges. The correctness of the dimensions of the opening of the workpiece being processed is established by the caliber. Fixture of tools in the chuck of the unit is carried out with the support of the shank.
For the cultivation of openings with a diameter of up to 10 cm, attachments with 4 points are used. Their main feature is fasteners through the mandrel. The presence of a chamfer on the teeth of the element made it possible to achieve the correct adjustment of the cut.
The design of the cone drill
This device is intended for passing cone-shaped openings of small depth. The main feature in the design of the element is the presence of straight type teeth and an absolutely flat outer base. The number of cut elements, in accordance with the calibration, can vary in the value of 6 - 12 units.
Reaming holes is considered a manual procedure carried out through a turning unit on which a countersink is mounted. The cultivated part is clamped in the patronage of the unit, its correct location in the recess is checked. The axial centers of the electrospindle and the rear assembly of the machine must be at the same level. This makes it possible to reduce the risk of a technically movable sleeve (quill) flying out. The tip of the instrumentation is given manually into the hole to be trimmed.
In order to obtain an opening of the desired diameter after the reaming operation, an allowance of 2-3 mm is made during drilling. The exact values of the allowance depend on the calibration of the recess in the cultivated workpiece. It is more difficult to implement the process of countersinking of forged and dense products. To simplify your task, you should bore out the countersunk hole by 5-9 mm in advance.
Reaming can be done in cutting order. In this situation, the tool feed is doubled compared to drilling, and the stroke speed remains the same. The deepening of cutting with a countersink is laid at about 50 percent of the allowance for the diameter. Countersinking of holes with a tool is implemented using cooling materials. The hard alloy mechanism does not require the addition of an auxiliary coolant.
The countersink when processing openings guarantees high accuracy, but marriage cannot be avoided at all. The most common processing defects are:
- Enlarged aperture. The main reason for the occurrence of such a flaw is the use of a device with incorrect sharpening.
- Reduced recess diameter. It happens that the wrong tools were chosen for the job or a damaged drill was used.
- Defiant purity. This flaw can be caused by a number of reasons. Usually, the decrease in cleanliness lies in the unimportant sharpening of the fixture. In practice, excessive viscosity of the material of the product can also serve as a cause of the defect. Therefore, the element sticks to the tool bands. Damage is also caused by the error of the turner, who made the wrong feed and cut acceleration.
- Partial processing of the opening. This cause usually occurs as a result of incorrect clamping of the part or an incorrect countersinking allowance saved after drilling.
Varieties and purpose of countersinks
A countersink resembles the type of drill that is used for countersinking. The operation is similar to reaming, but differ in the final task. The countersinking procedure is needed in situations where there is a need to form rounded recesses to hide the traces of fastener heads.
The cultivation of parts by countersink is classified as a semi-finishing method, and is carried out before the deployment operation.
According to the design of the countersink, they are divided into:
- rounded;
- Conical.
Under an independent category, countersinks consisting of hard alloys are distinguished. They are used as grinding actions. To process openings and remove chamfers in difficult areas, another type of tool is used - a reverse countersink. To ensure the necessary processing of metal products and wood, it is recommended to buy a countersink kit, and not individual fixtures.
A shank and an operated element, with an angular index of 60, 75, 90 and 120 degrees, fit into the structure of cone-type countersinks. The number of teeth varies in the range of 6 - 12 units, it depends on the diameter of the tool. To ensure the alignment of the cultivated opening, a trunnion is used.
The rounded countersink has a wear-resistant coating. This mechanism is used for chamfering. By design, it looks like a drill, but it has a large number of blades - from 4 to 10, it all depends on the diameter of the device. There is a suggestive trunnion on the end part of the element. With its help, the position of the instrumentation during the period of operation is fixed. The trunnion is detachable or integral. In practice, devices with detachable trunnions are used, due to ease of use. The countersink can also be fitted with a shell cutter.
To process several openings into an equal recess, a countersink with holders should be used, which includes various limiters. When processing the product, the cutting element is installed in the holder and leaves the stop by an amount equal to the recess of the opening.
Countersinks are made from various grades of steel, including carbide. Carbide tools are great for machining metal parts, as they can withstand extreme loads for a long time. For processing products made of non-ferrous metal alloy or wood, devices made of high-speed steel are used, since it is subjected to insignificant loads. It should be noted that when processing, for example, cast iron products, it is necessary to introduce additional cooling of the tools. For this, special emulsion formulations are used.
The principle of countersinking of metal products
During the processing of the opening created in the part during its casting, it is recommended to bore it several millimeters deep at once, so that the countersink selects the correct initial direction.
During the period of work in the processing of steel billets, it is recommended to use emulsion coolants. The procedure for countersinking of non-ferrous metals and cast iron does not require additional application of coolant. A very important stage is the correct selection of tools for the implementation of work. In this regard, focus on the following aspects:
- The variety of tools is selected in accordance with the harvesting materials and the nature of cultivation. Factors of the location of the hole and the number of processes are taken into account.
- Countersinks and a device for countersinking are selected depending on the specified parameters: the size of the recess, the diameter, the accuracy of work.
- The design of the metal-cutting tool is established based on the method of its fastening on the machine.
The choice of a countersink is made according to reference literature or using the normative act of the GOST 12489-71 standard:
- Workpieces made of structural steel with openings up to 40 mm in diameter are cultivated with a high-speed iron countersink, which includes 3-4 teeth and a diameter of 10-40 mm. In holes up to 80 mm, nozzles with a diameter of 32-80 mm are used.
- For hardened iron, when boring, equipment is provided with hard alloy plates, with a diameter of 14-50 mm and 3-4 teeth.
- For boring blind openings of cast iron products and non-ferrous metal parts, a pen drill is used.
A necessary condition for the reaming procedure is the observance of allowances. The diameter of the selected tool as a result must match the final diameter of the opening after processing. If, after reaming, it is planned to deploy the opening, then the diameter of the device is reduced by 0.15-0.3 mm. If it is planned to bore with a draft version or drill for countersinking, then the edge allowance should be kept from 0.5 to 2 mm.
Download GOST
GOST 12489-71 Solid core drills. Design and dimensions
GOST 14953-80 Conical countersinks. Specifications
oxmetall.ru
Countersinking and countersinking - how to process metal parts? + Video
Countersinking and countersinking are two different technological processes that are used in the processing of metal holes and surfaces. You will need special tools of various designs. In the first case, countersinks are used, in the second - countersinks. Next, we will analyze their features and differences.
After the drilling of a metal part is completed, it becomes necessary to make complex geometric recesses inside the part for the subsequent installation of various fasteners in them - bolts, screws, rivets. To do this, as well as, if necessary, qualitatively process the surface and chamfer inside the part, we take a countersink. This tool can be of various shapes. It can be selected, focusing on the final result. To date, there are conical, cylindrical or end (flat) countersinks. The latter are sometimes called countersinking, and countersinking of holes, as a technological process, can be called countersinking.
Countersinks of a cylindrical type are necessary to obtain holes of the appropriate shape in drilled sockets for the subsequent installation of bolts and screws of various types in them. The countersink has two parts - a working surface and a shank, as well as a special guide belt (trunnion), which is necessary to ensure tool alignment control in the process of working on the surface of a metal part.
Conical countersinks have a similar component, which includes a shank and a working part with belts, they provide alignment during operation.
Such countersinks are usually used to create holes in the form of a cone inside the part, chamfering and for recesses for bolts, various flat washers or thrust rings. Countersinks with a cone angle of 90 or 120 degrees are most widely used. Face or flat counterbores are mainly used for cleaning and processing metal recesses for installing fasteners. All countersinks differ in diameter, angle and modes of operation. Countersinking, as well as countersinking, is carried out on drilling, modular, milling and turning-milling machines.
Countersinking is a process of expanding and processing drilled metal holes of a stamped or cast type, which allows them to be given a strict geometric shape. Hole countersinking is an intermediate process that is most often needed after drilling and before metal reaming. With the help of high-quality equipment and tools, it is possible to achieve geometric holes of the fourth and sometimes fifth class of accuracy. The tool for countersinking is called a countersink.
Countersink for metal
Countersinks are of several types and differ in the number of teeth (three- or four-blade), and in design they can be solid, plug-in or mounted. Countersinks differ from a conventional drill by an enlarged bridge that connects the cutting edges, a cut corner, as well as the presence of a larger number of cutting teeth-edges. They allow you to ensure the stability of the tool during operation and the most accurate alignment of the countersink and the hole being machined.
Countersinking
The use of countersinks of a certain type directly depends on the diameter of the hole in the workpiece being processed. So, for holes with a diameter of less than 12 mm, one-piece countersinks are needed, for holes over 20 mm - plug-in type countersinks (with plug-in knives). If it is necessary to obtain more accurate and complex surfaces, combined types are used, in which there can be up to eight cutting edges, while prefabricated type countersinks can be additionally combined with drills, reamers and other tools.
3 Reaming - for maximum surface accuracy
Hole reaming is a complex technological process of finishing metal holes on milling equipment, which is performed after drilling and countersinking processes. With the help of deployment, it is possible to achieve a high class of accuracy. It is produced on manual and automated drilling or turning-milling machines with CNC or manual control. The tool that is used in deployment is called a sweep.
According to the type, the processing of the reamers can be manual or mechanical (machine), and in shape - cone-shaped or cylindrical. The tool consists of three parts with a gauge part and cutting edges that are evenly or unevenly distributed around the circumference. As a rule, reamers are used in a set of three, this is necessary to perform alternately roughing, semi-finishing and finishing. In this case, it is possible to achieve the maximum effect in surface treatment.
When deploying, a combined type of tool is also widely used, which includes a countersink, countersink, reamer, drill and other elements. The combination of tools can significantly reduce the time to obtain a hole of the desired shape, accuracy class and roughness. Drilling, like countersinking and reaming, can be called similar technological processes in certain operating modes. They are performed on similar types of manual and mechanical equipment.
tutmet.ru
Countersink - what is it, types and application, design, countersinking and GOST.
A countersink is a metal cutting tool with multiple working blades designed to process pre-drilled holes of a cylindrical or conical shape. With the help of a countersink, when choosing the required type of tool, it is possible to obtain recesses of various configurations in the holes of the workpieces. Countersinking should not be confused with countersinking, the full length reaming of holes to improve surface quality.
Types and application of countersinks
When processing parts on drilling and turning machines, metal countersinking is used for:
- Formation in pre-prepared holes of recesses of a conical or cylindrical shape of the required length.
- Formation of reference planes near the holes.
- Chamfering holes.
- Processing holes for fasteners.
You can often come across the term "counterbore", the so-called tool designed for drilling cylindrical recesses and supporting planes.
According to the configuration of the cutting part, the following types of countersinks are found:
- cylindrical configuration.
- Conical countersinks.
- End tools.
According to the diameter of the machined holes, countersinks are divided into:
- Simple (from 0.5 to 1.5 mm).
- For holes with a diameter of 0.5 to 6 mm. Available with or without safety cone.
- Countersinks with tapered shank. They are used for holes with a diameter of 8 to 12 mm.
Design
The conical countersink consists of two main elements - the working part and the shank. The working part has a cone with a standard range of angles at the top from 60 to 120°. The number of cutting blades depends on the diameter of the tool and can be from 6 to 12 pieces.
A cylindrical countersink is similar in design to a drill, but has more cutting elements. At the end there is a guide pin necessary for fixing the position of the tool during processing. The stop may be removable or be part of the body of the instrument. The first option is more practical, as it expands the processing capabilities. A cutting attachment can also be installed.
If it is necessary to drill several holes to an equal depth, a tool with holders with a rotating or fixed stop is used. Before processing, the countersink is fixed in the holder in such a way that the cutting part protrudes from the stop for a distance equal to the required hole processing depth.
The tool is made of tool alloyed, carbon, high-speed and hard-alloy steel grades. For the processing of cast iron parts, carbide steels are most often used, for ordinary steels - high-speed and tool steels.
Features of countersinking holes
- When machining hard alloys and cast iron, it is necessary to use cooling emulsion compositions to remove heat.
- It is very important to choose the right tool for the job. It is necessary to take into account the material of the workpiece and the nature of the work.
- When countersinking, pay special attention to the specified processing parameters - the diameter, the required accuracy, the size of the recess.
- Pay attention to the method of fixing on the machine, if necessary, purchase the necessary additional equipment.
Current GOST
Defines the technical conditions for the conical countersink GOST 14953-80. Also, when metalworking, one should be guided by other standards regulating the parameters of similar tools used - countersinks, reamers, etc. Countersinks must be selected according to tables in special literature.
mekkain.ru
Countersinking holes
Countersinking is the operation of processing the inlet or outlet of a hole in order to remove chamfers, burrs, and also to form recesses for the heads of bolts, screws and rivets. This operation is performed using a cutting tool called countersinks.
Countersinks according to the shape of the cutting part are divided into conical and cylindrical.
Conical countersinks (Fig. 78, a) consist of a working part and a shank. The working part of the countersink is characterized by a cone angle at the top 2f. The most widespread are conical countersinks with a cone angle at the top 2ср = 30, 60, 90 and 120°.
Rice. 78. Conical (a) and cylindrical (b) countersinks
Cylindrical countersinks (Fig. 78, b) also consist of a working part and a shank. The working part of countersinks has face teeth. The number of teeth of these countersinks is from 4 to 8. Cylindrical countersink has a guide pin that enters the drilled holes, which ensures that the axis of the hole and the cylindrical recess formed by the countersink coincide.
Conical and cylindrical countersinks are made from tool carbon and alloy steels U10A, U12A and 9XC.
For countersinking holes, special holders with countersinks with non-rotating and rotating stops are also used.
A holder with a countersink and a rotating limiter (Fig. 79) consists of a shank 7, at one end of which a countersink 3 with a guide pin 1 is threaded. sleeve 6 and stop 2. The countersink protrudes from the stop to the depth of the countersink hole.
Rice. 79. Holder with countersink and rotating stop
The limiter makes it possible to countersink holes to the same depth, which is difficult to achieve using conventional countersinks.
For countersinking holes, holders with a countersink and a limiter are also widely used, but without a guide pin. The holder of this design (Fig. 80) consists of a sleeve 4, a lock nut 3, a limiter 2, a shank 5, a countersink 1, a holder 6 and a thrust bearing 7. This holder works in the same way as a holder with a rotating limiter.
Rice. 80. Holder with countersink and limiter, but without guide pin
Hole countersinking is performed on drilling machines or pneumatic and electric drilling machines, for which the countersink shank is securely fixed in the chuck of a drilling machine or a drilling machine.
The outlet part of the holes (Fig. 81, a) is processed with conical countersinks to obtain conical recesses for the heads of countersunk screws, rivets.
Rice. 81. Processing a hole with a conical countersink (a) and a hole machined with a cylindrical countersink (b)
Countersinking recesses for the heads of bolts, rivets (Fig. 81, b), as well as cutting the ends of the boss planes, selecting ledges and corners is carried out with cylindrical countersinks.
When countersinking holes, follow the rules for performing work methods and precautions related to drilling holes.
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Countersinking and countersinking - Metal drilling
Countersinking and countersinkingMetal drilling
Countersinking and countersinkingCountersinking is the processing of the exit part of a hole, for example, removing burrs from the edges of a hole, expanding center holes, and forming recesses for countersunk heads of screws and rivets. The tool used for this purpose is called a countersink. According to the shape of the cutting part, countersinks are divided into conical and cylindrical, having end teeth and equipped with a trunnion.
Conical countersinks are designed to remove burrs in the exit part of the hole, to obtain a conical recess in the hole for the support of the conical heads of screws and rivets, and for centering the holes. The most widespread are conical countersinks with a cone angle at the top of 30, 60, 90 and 120 °.
Cylindrical countersinks with face teeth1 are used to expand the output part of cylindrical holes for screw heads, for flat washers, as well as for cutting ends, boss planes, for selecting ledges and corners. The number of teeth on these countersinks is from 4 to 8.
On fig. 190 shows countersinks of various types and examples of their processing of holes.
Countersinking is the processing of finished holes obtained by casting, stamping or drilling, in order to give them a strictly cylindrical shape, greater accuracy and better surface finish. After the countersink, the hole is obtained with the 4th and 5th accuracy classes.
Holes of the 2nd and 3rd accuracy classes are obtained by deployment. Therefore, countersinking can also be an intermediate operation between drilling and reaming.
Countersinks (Fig. 191) are divided into solid and mounted, and by the number of teeth (feathers) - into three- and four-blade. A solid countersink has three or four cutting edges, and a mounted countersink has four cutting edges. For processing holes with a diameter of 12-35 mm, one-piece countersinks are used, and for processing holes with a diameter of 24-100 mm, mounted countersinks are used.
Countersinking and countersinking, as well as the drilling process, occurs with two joint relative movements of the tool - rotational and translational along the axis. The drill selected for drilling a hole for processing with a countersink must have a diameter reduced against the diameter of the finished hole by the amount of the allowance. In table. 12 shows the diameters of the countersinks and the recommended allowances (per side) for countersinking.
Rice. 1. Countersinks: a - for processing holes for the conical head of the screw, b - examples of work with conical countersinks, c - countersinks for processing holes for cylindrical heads and necks, d - hole countersinked for the cylindrical head of the screw, e - hole countersinked for the neck screws, e - connection of parts with a screw through a countersunk hole
Rice. 2. Countersinks: a - one-piece, b - mounted, c - rod for mounting the head of the countersink
Rice. 3. Manual (left) and machine reamer: L - working (lead-in) part of the reamer, B - calibrating part, C - neck, G - shank, D - square head for gripping the reamer with a crank when manually deploying
To increase the diameter of a hole obtained by drilling, casting or stamping, as well as to obtain conical and cylindrical recesses, cleaning the end surfaces of bosses and hubs, the following technological operations are used: countersinking, countersinking and countersinking (Fig. 9.1).
Countersinking called the process of processing pre-drilled, stamped, cast holes in order to give them a more regular geometric shape (eliminate deviations from roundness and other defects), achieve higher accuracy (9 ... 11 grades) and reduce surface roughness to R a = 1.25...2.5 µm. This processing can be either final or intermediate (semi-finishing) before reaming, which gives even more accurate holes (6...9th grade) and surface roughness up to R a =0.16...1.25 µm. When processing precise holes with a diameter of less than 12 mm, reaming is used immediately instead of countersinking.
According to the design of the countersink, there are solid (Fig. 9.17, a) and mounted ones (Fig. 9.17, b). To save high speed steel, countersinks are also made with insert knives or brazed carbide inserts.Countersinking the process of processing with a special tool is called countersinks of conical recesses and chamfers for the heads of bolts, screws, rivets. Unlike countersinks, countersinks have cutting teeth at the end, sometimes they also have guide pins, with which countersinks are inserted into the drilled hole, which ensures that the axis of the hole and the recess formed by the countersink for the screw head coincide. Fastening countersinks and countersinks on drilling machines is no different from fastening drills.
deployment called the process of final finishing of holes, providing high dimensional accuracy and surface roughness within R a =1.25 ... 0.16 μm. The reaming of holes is performed both on drilling and other metalworking machines, and manually during metalwork and metalwork-assembly processing. Manual reamers (Fig. 9.18, a) - with a straight and helical tooth, mounted, adjustable - are equipped with a square end on the shank for rotating them with a knob.
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For processing conical holes, most often for Morse cones, conical manual reamers are used in sets of two and three pieces (Fig. 9.18, c). The first scan is rough (rough), the second is intermediate and the third is fair (final), giving the hole its final dimensions and the required surface roughness.
The main parts and geometrical parameters of manual scanning are shown in fig. 9.19. The reaming allowance should be no more than 0.05...0.1 mm per side. A larger allowance can lead to a rapid blunting of the reamer chamfer, an increase in the surface roughness of the hole and a decrease in machining accuracy.
Manual hole reaming exercises involve a number of tricks. When starting to ream, you must: select the required reamer (check its marking), make sure that there are no nicks and chipped places on the cutting edges, fix the workpiece in a vice or place it on a workbench (plate) in a position convenient for work, take a rough reamer , lubricate the intake part with mineral oil and insert it into the hole without skew, check the position of the reamer with a square (90 0), put the knob on the square of the reamer shank, slightly pressing the reamer with your right hand down, slowly rotate the knob clockwise with your left hand, periodically removing reamer from the hole to clean it from chips and lubricate, finish the reaming when ¾ of the working part of the reamer comes out of the hole. When reaming deep holes located in hard-to-reach places of the part, it is necessary to use special extensions that are put on the square of the reamer shank.
In the same sequence, the final (finish) deployment is performed.
The collar must be rotated slowly, smoothly and without jerks. Reverse rotation of the reamer is not allowed, as it may cause burrs on the hole surface or breakage of the cutting edges of the reamer.
Manual deployment techniques are shown in Fig. 9.20, a ... c.
Machine reaming exercises are performed on drilling machines in the same way as drilling. Reaming is best done immediately after drilling and countersinking with one installation of the workpiece in a vice or fixture. The reamer is fixed with a chuck or adapter bushings in the cone of the machine spindle. In some cases, to ensure a more accurate coincidence of the axes of the scan, they are fixed in floating (oscillating) holders. The cutting speed (spindle speed) during reaming should be 2...3 times less than when drilling with a drill of the same diameter. Reaming is carried out with a mechanical feed, which depends on the diameter of the reamer, the material of the workpiece and is taken within 0.5 ... 2.0 mm / rev. As a cutting fluid, they are used: when processing steel and bronze billets - a solution of emulsol, sulfofresol, mineral oil; when processing cast iron and aluminum alloys - kerosene, turpentine; when processing ductile iron and brass - emulsol solution. Exercises in machine reaming, countersinking and reaming can in some cases be combined with drilling exercises on drilling machines.
The quality of the surface of the reamed hole is checked after thorough wiping by external examination "in the light" to detect scuffing, faceting, crushing traces. The accuracy of a hole is determined depending on its size and the required quality of accuracy with plug gauges, indicator inside gauges, and holes with a diameter of more than 50 mm - with micrometer inside gauges.
The safety rules for reaming, countersinking and countersinking are the same as for drilling.
The essence of the drilling process.
Drilling is the process of removing metal to make holes. The drilling process includes two movements: tool rotation V(fig. 48) or parts around the axis and feed S along the axis. The cutting edges of the drill cut off thin layers of metal from a fixed part, forming chips that, sliding along the spiral grooves of the drill, exit the hole being machined. The drill is a multi-blade cutting tool. Not only the two main blades are involved in cutting, but also the jumper blade, as well as two auxiliary drills located on the guide ribbons, which greatly complicates the process of chip formation. When considering the scheme of chip formation during drilling, it is clearly seen that the working conditions of the cutting edge of the drill at different points of the blade are different. So, the rake angle of the cutting edge at(fig. 49),
Rice. 48. Scheme of cutting when drilling. Forces acting on the drill
Rice. 49. Chip formation during drilling
located closer to the periphery of the drill (section A-A), is positive. The cutting edge works in relatively light conditions.
The front angle of inclination of the cutting edge, located further from the periphery, closer to the center of the drill (section B-B), is negative. The cutting edge works in more difficult conditions than those located closer to the periphery.
Cutting with a transverse cutting edge (section C-C) is a cutting process close to extrusion. When drilling, compared to turning, the conditions for chip removal and coolant supply are much worse; there is a significant friction of the chips on the surface of the drill grooves, the friction of the chips and the drill on the machined surface; along the cutting edge there is a sharp difference in cutting speeds - from zero to a maximum, as a result of which at various points of the cutting edge the cut layer is deformed and cut off at different speeds; along the cutting edge of the drill, the deformation is different - as it approaches the periphery, the deformation decreases. These features of cutting during drilling create more difficult conditions for chip formation compared to turning, an increase in heat generation and increased heating of the drill. If we consider the process of chip formation in individual micro sections of the cutting edge, then elastic and plastic deformations, heat generation, build-up formation, hardening, and tool wear arise here for the same reasons as in turning. Cutting temperature in drilling is more influenced by cutting speed than by feed.
Fig.50. twist drill
Drill elements. The most common and universal purpose is a twist drill (Fig. 50). The drill consists of a working part, a conical or cylindrical shank, which serves to fix the drill, and a paw, which is a stop when the drill is removed. The working part of the drill is a cylindrical rod with two spiral or helical grooves, along which chips are removed. The cutting part is sharpened along two conical surfaces, has a front and back surfaces (Fig. 50) and two cutting edges connected by a jumper at an angle of 55 °. On the cylindrical part, two narrow ribbons pass along the helical line, centering and guiding the drill in the hole. Ribbons significantly reduce the friction of the drill on the walls of the hole being machined. To reduce friction of the working part of the drill towards the shank, a reverse cone is made. The drill diameter decreases for every 100 mm of length by 0.03-0.1 mm.
The cutting part of the drill is made from tool steels in hard alloys. Like the cutter, the drill has front and back angles (Fig. 51). Front angle at(section B-B) at each point of the cutting edge is a variable value. The largest value of the angle at has on the periphery of the drill, the smallest at the top of the drill. Due to the fact that the drill not only rotates during operation, but also moves. along the axis, the actual value of the relief angle a different from the angle, by-. radiated during sharpening. The smaller the diameter of the circle on which the considered point of the cutting edge is located, and the greater the feed, the smaller the effective relief angle.
The actual rake angle during cutting will accordingly be greater than the angle measured after sharpening. To ensure a sufficient clearance angle in work
Rice. 51. Front and rear corners of the drill
(at the points of the cutting edge close to the axis of the drill), as well as the angle of sharpening of the tooth along the axis of the entire length of the cutting edge, the clearance angle is made: on the periphery 8-14 °, and at the middle 20-27 °, the clearance angle on the drill ribbons is 0°.
In addition to the front and rear angles, the drill is characterized by the angle of inclination of the helical groove 
, the angle of inclination of the transverse edge 
, vertex angle 2 
, angle of inverse taper 
(Fig. 50). 
=18-30°, 
=55°, 
=2-3°, for tool steel drills 2 
=60-140°.
Types of undercuts and various forms of sharpening are shown in fig. 52.
Rice. 52. Elements for sharpening twist drills
Cutting Mode Elements(fig.53). As already mentioned, the cutting speed at different points of the cutting edge is different and varies from zero in the center to a maximum at the periphery of the drill. When calculating cutting conditions, the highest cutting speed at the periphery is taken (in m/min)
where D-
drill diameter, mm; n- drill rotation frequency, rpm; 
- coefficient equal to 3.14.
Rice. 53. Cutting elements: a- when drilling 6 - when reaming
Drilling feed s (mm / rev) is the amount of movement of the drill along the axis for one revolution of the drill or for one revolution of the workpiece, if the workpiece rotates, and the drill only moves. The drill has two main cutting edges. Feed per edge
Minute feed (mm/min)
s m = sn.
slice thickness a, measured in the direction perpendicular to the cutting edge:
Cutting width b measured in the direction along the cutting edge and is equal to its length:
Forces acting on the drill. When drilling holes, the material resists chip removal. During the cutting process, a force acts on the cutting tool that overcomes the resistance force of the material, and a torque acts on the machine spindle (see Fig. 48).
Let us decompose the resultant resistance force on each cutting edge into force components in three mutually perpendicular directions: R Z , P B , R G(see fig. 48). Horizontal (radial) forces R G. acting on both cutting edges are mutually balanced due to the symmetry of the twist drill. With asymmetric sharpening, the length of the cutting edges is not the same and the radial force will not be equal to zero, as a result, the tip is squeezed out and the hole is broken. Forces R AT upwards, prevent the drill from penetrating into the depth of the workpiece. Forces acting in the same direction R 1 transverse edge. In addition, the movement of the drill is hindered by friction forces on the drill bits (friction on the machined hole surface) and friction forces from descending chips. R T . The total force from the specified resistance forces in the axial direction of the drill is called the axial force R or feed force:
P= 
(2R AT +P 1
+P T ).
Resistance forces R AT , arising on the cutting edges and interfering with the penetration of the drill, are 40% of the force R; resistance forces R 1 , arising on the transverse edge, account for 57% and the friction forces R T- about 3%.
The total moment of resistance forces
Rice. 54. Types of drills: a, b - spiral, in- with straight grooves G - feather, d- rifle, e- single-edged with internal chip removal, f - two-edged, h - for core drilling, and- centering to - screw.
cutting M is made up of torque R z , moment from the forces of scraping and friction on the transverse edge M PC , moment from friction forces on the ribbons M L and the moment from the forces of friction of the chips on the drill and the machined surface of the hole M With , i.e. M=M SR +M PC +M L +Ms.
By strength R and moment M the required power of the drilling machine is calculated.
Wear and durability of drills. The wear of drills occurs along the back surface, ribbons and corners, and sometimes the front surface of drills, with carbide plates - along the corners and ribbon.
The durability of the drill depends on the material of the workpiece and tool, on the quality of the tool, on the cutting conditions, on the coolant used, etc.
Typesdrills and their device. A drill is a tool that makes holes or increases the diameter of a previously drilled hole.
On fig. 54 shows various types of drills: feather (Fig. 54, d), two-edged (Fig. 54, g), spiral (Fig. 54, a and b), gun (Fig. 54, e) for ring drilling (Fig. 54, h), centering (Fig. 54, i), screw (Fig. 54, to).
A spade drill is a round rod, at the end of which there is a flat blade with cutting edges inclined to each other at an angle of 120 °. Perovye drills have insufficient rigidity. The disadvantage of a single-lip drill is the need for a guide bushing, as well as a limited space for chip evacuation.
The twist drill is the most widely used in industry. Its device is described above (see Fig. 50). Other types of drills have a special purpose.
Auger drills make it possible to obtain holes up to 40 diameters deep in one stroke without periodic withdrawals for chip removal. They allow you to work at higher cutting speeds, which, combined with a reduction in auxiliary time (no intermediate drill leads), gives a productivity increase of 2-3 times compared to working with long standard drills.
Drills equipped with carbide. Drills equipped with tungsten carbide inserts have long tool life, high speeds, high surface quality and high productivity. They can process parts made of cast iron, hardened steel, glass, marble, plastics, etc. The use of carbide inserts is especially effective when drilling cast irons and reaming cast irons and steels.
Carbide drills have a rake angle at=0-7°; back angle a=8-16°, angle 2 
=118-150°. On fig. 55 shows several types of carbide drills. The drill designed by the Institute of Hard Alloys (Fig. 55, a) is made with a steel shank. The VNII drill (Fig. 55.6) is made entirely of hard alloy. Small carbide monolithic tools (drills, taps, reamers up to 6 mm) are made from carbide rods by grinding. Monolithic drills are made from VK6M, VK8M and VK10M alloys. They are designed for processing refractory metals - tungsten, beryllium, titanium and molybdenum alloys, high-strength cast irons, stainless, chromium-nickel, heat-resistant steels and alloys. Solid carbide drills cost 10 times more than HSS drills.
Rice. 55. Carbide drills: a- with steel shank b- made according to the VNII method, in- with oblique grooves, equipped with hard alloy, G- spiral, equipped with a hard alloy plate, d-s straight flute with carbide insert
Drills with oblique grooves (Fig. 55, c) consist of a holder, in the groove of which a plate of VK8 alloy is soldered. .Such drills are used for drilling shallow holes. Drills with helical grooves (Fig. 55, a) are used for drilling parts made of ductile and brittle metals at high operating conditions. On fig. 55, d shows a drill with straight flutes of the Moscow plant "Frezer", designed for drilling parts made of cast iron and brittle materials with a depth of ( 2-3) D. When machining steels, it is recommended to use T15K6 hard alloy, when machining cast irons - VK8 alloy. When processing with carbide drills, it is necessary to maintain the symmetry of sharpening drills.
Drills with rotary non-regrindable carbide inserts. On fig. 56 shows a drill with two triangular non-regrindable carbide inserts. Records 1 and 2 located in two rectangular grooves 6 in special nests 3 and fixed with bolts 7. The plates are arranged so that their cutting edges form mutually overlapping cutting surfaces. The plates are, as it were, turning cutters, mounted in a holder 4, inserted into the sleeve 5. Process
Rice. 56. Drill with rotary fixed plates
cutting with this drill becomes a turning process with two cutters, allowing you to use the performance and simplicity of modern turning cutters. The shape of the blades and their arrangement means that the drill does not need to pre-prepare the hole. This drill allows you to drill in both directions, withdraw and insert the drill again. The drill is designed for holes from 18 to 56 mm and up to two drill diameters deep. When using double-coated inserts, it is possible to work at feed rates significantly higher (up to 5 times) than those used when working with twist drills, obtaining the same surface finish.
The use of drills with non-regrind indexable inserts transforms the drilling operation from slow to fast and cheap. Given that the operation of drilling shallow holes in CNC machines, modular machines and automatic lines is common and widespread, the processing technology using drills with non-regrind indexable inserts will be progressive.
For drilling deep holes, long drills are used with non-regrinding rotary plates of the “Ejector” type (Fig. 57), which have an independent coolant supply and chip removal device. Deep hole drill 2 is paired with drill 1. The drilling operation is performed in two working steps.
Rice. 57. Deep Hole Drill with Ejector Inserts
First, a shallow hole is drilled with drill 1. Then, a final deep hole is drilled with drill 2.
Countersinking and deployment
The reaming process is carried out by a countersink. The reaming operation is more precise than drilling. Drilling achieves the 11-12th grade and surface roughness R z 20 microns, and by countersinking - 9-11th grade and surface roughness Ra 2.5 µm.
Reaming is a more precise operation than drilling and reaming. Deployment achieves 6-9th grade and surface roughness Ra 1.25-0.25 µm.
The reaming operation is similar to reaming. On fig. 58 shows the design of the drill. The drill consists of a working part 1, a neck 2 and a shank 3.
The working part consists of a cutting part l 1
and calibrating l 2
.
The cutting (fence) part is inclined to the axis at the main angle in the plan 
and performs the cutting. Usually in steel processing 
=60°, for cast iron -
45-60°. For countersinks equipped with carbide blades, 
=60-75°. Helix Angle 
= 10-30°, when machining cast iron 
>0.
On fig. 58 shows countersinks of various designs used when working on modular machines and automatic lines.
Rice. 58. Zenkers: a- one-piece with a tapered shank, b-one-piece, in- mounted with stacked legs, G- equipped with a hard-alloy plate, d- with direction for cylindrical recesses
Countersinks with a tapered shank (Fig. 58, a) with a minimum number of teeth z<3, диаметром 10 мм и выше применяются для окончательной обработки и под развертывание. Зенкеры насадные и со вставными ножами (рис. 58,b and in) are used for drilling holes.
Countersinks are made of high-speed steels P18 and P9 and hard-alloy materials T15K6 used in the processing of steels, and VK8, VK6 and VK4 in the processing of cast irons.
The reaming process is a finishing operation to obtain precise holes. Cutting is carried out by reaming. As stated, reaming is a more precise operation than drilling and countersinking. The reamer in many ways resembles a countersink, its main difference from a countersink is that it removes a much smaller allowance and has a large number of teeth - from 6 to 12. The reamer consists of a working part and a shank (Fig. 59). The working part, in turn, consists of a cutting part AT and calibrating G. The cutting part is inclined to the axis at the main angle in the plan 
and performs the main work of cutting. The angle of the cone of the cutting (intake) part is 2 
.
Rice. 69. Sweep
The calibrating part of the reamer consists of two sections: cylindrical D and conical E, the so-called inverse cone. The reverse taper is made to reduce the friction of the tool on the machined surface and increase the diameter of the hole. Front sweep angle at equal to 0-10° (0° is accepted for finishing work and when cutting brittle metals). Rear angle a 6-15° is made on the cutting part of the reamer (large values for small diameters). The rear angle on the calibrating part is equal to zero, since there is a cylindrical ribbon.
Leading angle 
for machine reamers (from tool steels) when machining tough steels it is 15°, when machining cast irons 5° .
When deploying blind and through holes of the 9th grade and coarser 
=45-60°. For reamers equipped with carbide inserts, 
=30-45°.
On fig. 60, 61 show various types of sweeps. According to their design, reamers are divided into manual and machine, cylindrical and conical, mounted and solid.
Rice. 60. Types of sweeps
Rice. 61. Machine adjustable reamers
Manual reamers are made with a cylindrical shank (Fig. 60, d). They process holes from 3 to 50 mm. Machine reamers (fig. 61) are made with cylindrical and tapered shanks and are used to ream holes with a diameter of 3 to 100 mm. These reamers are used to machine holes on drilling and turning machines. Shell reamers are used to ream holes from 25 to 300 mm. They are mounted on a special mandrel with a tapered shank for mounting on the machine. Shell reamers are made of high speed steel P9 or P18 and equipped with hard alloy plates.
Tapered holes are deployed with conical reamers. Typically, the kit includes three reamers: peeling, intermediate and finishing. Solid reamers are made from carbon or alloy steel. When reaming holes in hard metals, reamers with hard alloy plates are used.
elem cutting and shearing parameters for countersinking and reaming. The elements of the cutting mode are calculated according to the formula and methodology given in the "Drilling" section (coefficients and exponents are selected from tables and reference books in relation to a specific operation).
Depth of cut t(Fig. 62 and 63) are determined based on the processing allowance for countersinking up to 2 mm per side. The average values of the allowance for countersinking after drilling, removed in one working stroke (i.e. t= h), are:
Rice. 62. Elements of cutting when reaming
The allowance for fine reaming is taken 0.05-0.25 mm per side. Allowance for pre-deployment can be increased by 2-3 times. Average depths
cutting (allowance) at finishing deployment are:
slice thickness a when deployed (Fig. 63) is usually insignificant and amounts to 0.02-0.05 mm.
Machine time (in. min) during countersinking and reaming
where L
-
the path traversed by the tool in the feed direction, mm; l- depth of reaming or reaming, mm; U- infeed value, mm (Fig. 62.6); 
\u003d 1-3 mm - overrun value, mm.
Rice. 63. Cutting elements during deployment
In the work of a locksmith in the manufacture, repair or assembly of parts of mechanisms and machines, it often becomes necessary to obtain a wide variety of holes in these parts. To do this, the operations of drilling, countersinking, countersinking and reaming holes are performed.
The essence of these operations lies in the fact that the cutting process (removing a layer of material) is carried out by rotational and translational movements of the cutting tool (drill, countersink, etc.) relative to its axis. These movements are created using manual (rotary, drill) or mechanized (electric drill) devices, as well as machine tools (drilling, turning, etc.).
Drilling is one of the types of obtaining and processing holes by cutting using a special tool - a drill.
Like any other cutting tool, the drill works on the principle of a wedge. By design and purpose, drills are divided into spade, spiral, centering, etc. In modern production, mainly spiral drills are used and less often special types of drills.
On the guide part there are 2 helical grooves, along which chips are removed during the drilling process. The direction of the helical grooves is usually right. Left drills are used very rarely. Narrow stripes on the cylindrical part of the drill are called ribbons. They serve to reduce the friction of the drill against the walls of the hole (drills with a diameter of 0.25-0.5 mm are made without ribbons).
The cutting part of the drill is formed by 2 edges located at a certain angle to each other (corner angle). The angle value depends on the properties of the material being processed. For steel and cast iron of medium hardness, it is 116-118 °.
The shank serves to secure the drill in the machine spindle or drill chuck and can be conical or cylindrical. The tapered shank has a paw at the end, which serves as a stop when pushing the drill out of the socket.
The neck drill connects the working part and the shank and serves to exit the abrasive wheel in the process of grinding the drill during its manufacture. The drill mark is usually affixed to the neck.
Drills are made mainly from high-speed steel or hard sintered alloys of grades VK6, VK8 and T15K6. Only the working (cutting) part of the tool is made from such alloys.
During operation, the cutting edge of the drill is dulled, so the drills are periodically sharpened.
Drills produce not only drilling of deaf (drilling) and through holes, i.e. obtaining these holes in a solid material, but also reaming - an increase in the size (diameter) of holes already obtained. Feather drills are the simplest in design. They are used in the processing of solid forgings, as well as stepped and shaped holes.
A special group of drills are center drills designed for processing center holes. They are simple, combined, combined with a safety cone. Simple twist drills differ from conventional twist drills only in the shorter length of their working part, since they drill holes of small length. They are used in the processing of high-strength materials, while combination drills often break.
Countersinking is the processing of the upper part of the holes in order to obtain chamfers or cylindrical recesses, for example, under the countersunk head of a screw or rivet.
Countersinking is performed using countersinks or a larger diameter drill;
Countersinking is the processing of holes obtained; casting, stamping or drilling, to give them a cylindrical shape, improve accuracy and surface quality. Countersinking is performed with special tools - countersinks.
Countersinks can be with cutting edges on a cylindrical or conical surface (cylindrical and conical countersinks), as well as with cutting edges located on the end (end countersinks). To ensure the integrity of the hole being processed and the countersink, a smooth cylindrical guide part is sometimes made at the end of the countersink. 
Countersinking can be a finishing process or pre-deployment process. In the latter case, when reaming, an allowance is left for further processing.
Reaming is the finishing of holes. In essence, it is similar to countersinking, but provides higher accuracy and low surface roughness of the holes.
Hole reaming tool - reamer. Hand reamers have a square end on their tail for turning them with a crank. On machine reamers, the shank is tapered.
For the processing of conical holes, a set of conical reamers of three pieces is used: roughing (peeling), intermediate and finishing. Smooth cylindrical holes are machined with straight fluted reamers. If there is a keyway in the hole, then tools with spiral grooves are used to deploy it.
When working on drilling machines, various devices are used to secure workpieces and cutting tools.
Machine vice - a device for fixing workpieces of different profiles. They may have interchangeable jaws for clamping complex shapes.
Prisms are used to fix cylindrical workpieces.
In drilling chucks, cutting tools with cylindrical shanks are fixed.
With the help of adapter bushings, cutting tools are installed, in which the size of the shank cone is smaller than the size of the machine spindle cone.
On drilling machines, all basic operations for obtaining and processing holes by drilling, countersinking, countersinking and reaming can be performed.
Vertical drilling machines are used for drilling holes with a diameter of up to 75 mm. They can provide reaming, countersinking, reaming and threading operations.
Table drilling machines are used for drilling holes in small parts with a diameter of up to 12 mm.
Safety precautions when drilling metal:
Work on a working drilling machine (serviceable safety guards, grounding, reliable installation of the chuck on the machine spindle).
Clamp the workpiece securely on the drill table.
It is forbidden to touch the rotating chuck of the machine.
While drilling, put on a hat, make sure that all the buttons on the clothes are fastened.
Do not hold the workpiece with your hands while drilling.
At the end of drilling, slow down the feed of the drill.
Do not remove sawdust after drilling with your hands.