Installing a cutter on a vertical machine. Installation of cutters in machines. Technical requirements for milling tools. Existing tool types
General instructions for securing cutters
The cleanliness of processing and the productivity of the machine largely depend on the quality of fixing the cutter on the machine.
If the cutter is not secured correctly, it will hit, as a result of which the load on individual teeth will be excessive and they may break. If the cutter is installed far from the spindle support, the arbor may be pressed out.
The mandrels with which the cutters are secured must be kept clean; they should not be hammered, remembering that any nick leads to beating of the cutter.
The method of securing the cutter to the machine depends on its design and size, as well as on the nature of the work performed by the cutter.
Let's look at the main methods of attaching cutters.
1. The cutter is put on center a mandrel, one end of which fits into the conical socket of the spindle, and the other is supported by an earring.
2. The cutter is put on an end mandrel, which with its conical end fits into the conical socket of the spindle.
3. The cutter with a conical shank is installed with the shank into the conical socket of the spindle.
4. The cutter is secured with a cylindrical shank in the spindle socket using special chucks.
5. The cutter is put on the protruding front end of the spindle and secured to it.
The milling operator must know the type and number of the spindle socket cone of his machine and the mounting dimensions of the front end of the spindle. Domestic milling machines have standard size spindle front taper (see Fig. 22), so milling arbors made with standard shanks fit them.
In Fig. Figure 43 shows mandrels with a conical shank 1, which corresponds to the conical socket 2 (see Fig. 22) of the front end of the spindle of domestic milling machines and is centered in it. Recesses 2 (Fig. 43) in the mandrel flange are put on leads 3 (see Fig. 22), inserted into grooves at the end of the spindle.
The center mandrels (Fig. 43, a and b) are fixed at one end in the slot of the machine spindle, and at the other they are supported by the shackle bearing. The mandrel (Fig. 43, a) for fastening cutters operating under high forces has a large length, allowing the use of an additional shackle in the middle. Mandrel in Fig. 43, b is intended for light work.
The end mandrels (Fig. 43, c) are fixed at one end in the slot of the machine spindle, and at the other end of the mandrel a mounted cutter is fixed, which works together with the mandrel as an end mill.
Fastening cutters to center mandrels
In Fig. 44 shows various cases of fixing cutters on center mandrels. The tapered mandrel shank is included in conical hole 8 of the spindle, the other end goes into bearing 1 of the earring.
In Fig. 44, and shows the mounting on a mandrel of a cylindrical cutter 5 with helical teeth. The cutter is put on the middle (working) part of the mandrel and can be installed anywhere on the mandrel using installation rings 3, 4, 6 and 7. The rings are put on the mandrel in the same way as the cutter 5. The leftmost ring 7 rests against the shoulder of the existing on the mandrel, and the rightmost ring 5 is supported by nut 2, screwed onto the right end of the mandrel.
Figure 44, b shows the mounting of several cutters on a mandrel close to one another (a set of cutters); The width of the mounting rings is different here.
The normal set of mounting rings included with milling machine, consists of rings with a width from 1 to 50 mm: 1.0; 1.1; 1.2; 1.3; 1.4; 1.5; 1.6; 1.7; 1.8; 1.9; 2.0; 3.0; 5.0; 8.0; 10; 15; 20; thirty; 40 and 50 mm.
Using mounting rings, the cutters can be secured at a certain distance from each other. In Fig. 44, c shows the fastening of two cutters at a distance A from each other. Distance A is established by selecting rings.
Sometimes, when adjusting the distances between the cutters on the mandrel, you have to place thin spacers made of aluminum or copper foil and even writing or tissue paper between the adjusting rings, since sometimes, using the rings included in the set, it is not possible to obtain the required distance between the cutters.
Cutters of small diameters, operating with little force, are kept on the mandrel from turning by friction between the ends of the cutter and the ends of the rings, which occurs when tightened with a nut. At hard work this friction is not enough, and the cutter is held on the mandrel with a key. A keyway is milled along the entire length of the middle (working) part of the mandrel; a key is attached to it, onto which the cutter is put. In this case, the rings are also placed on the key.
The holes in the rings, as well as the working parts of the milling mandrels, are made only of certain diameters. At domestic factories, mandrels with a diameter of 16; 22; 27; 32; 40; 50 and 60 mm. Keyways and keys are also made in specific sizes, so that the milling cutters, mandrels, rings and keys of the same value available in the tool store will definitely fit each other.
Milling mandrels must be straight, without nicks or dents, and the rings must have ends without nicks or burrs.
When installing cutters, you should place them as close to the front end of the machine spindle as possible to reduce the load on the mandrel. If for some reason this fails, you need to install an additional shackle, which provides additional support and relieves the load on the milling mandrel.
In Fig. Figure 45 shows an additional shackle on the machine when milling a block with a wide cutter.
The procedure for installing and securing the cutter on the mandrel and securing the mandrel in the slot of the machine spindle is described in detail when considering setting up the machine.
Securing cutters to end mandrels
The cutters, which operate with teeth located on the end surface, are mounted on end mandrels.
In Fig. 46 shows an end mandrel. The conical end 1 is inserted into the conical socket of the machine spindle. The cutter is put on the cylindrical part of the mandrel and tightened with screw 3. To prevent the cutter from turning, there is a key 2 on the mandrel.
Clamping of cutters with conical and cylindrical shank
Milling cutters with a conical shank, the size of which coincides with the dimensions of the conical socket of the machine spindle, are inserted with the shank into the spindle and secured in it using a tightening screw (ramrod). This is the easiest way to secure a cutter for both horizontal and vertical milling machines.
If the size of the cutter shank taper smaller size spindle socket cone, then resort to adapter bushings (Fig. 47). Outer cone Such a sleeve corresponds to the socket of the machine spindle, and the inner one corresponds to the shank of the cutter. The adapter sleeve with the inserted cutter is installed in the spindle and tightened using a tightening screw.
Milling cutters with a cylindrical shank are secured using a chuck (Fig. 48). The cutter is inserted into cylindrical hole chuck 1 and secured with a nut 2, screwed onto the front end of the chuck and enclosing the expanding sleeve 5 with its shoulders. The chuck with the mounted cutter is installed in the spindle of a horizontal or vertical milling machine and secured with a tightening screw. The cutter is removed by releasing nut 2.
Clamping of large diameter sheath cutters
Face milling cutters with diameter 125 mm and higher are made mounted. Such cutters can have conical(Fig. 49, a) or cylindrical(Fig. 49, b) mounting hole.
Milling cutters with conical landing The hole is placed on the cone 2 of the milling mandrel (Fig. 50 and 51) and secured to it using the liner 3 and screw 4. Insert 3 fits into a groove in the cutter body. Mandrel in Fig. 50 together with the cutter is attached to the spindle of the milling machine with a tightening screw (ramrod), which is screwed into the threaded hole of the mandrel. Mandrel in Fig. 51 together with the cutter is put on a cylindrical belt 5 on the end of the spindle of the milling machine and secured to it with four screws 1 (see also Fig. 22). To prevent the mandrel from being turned, it has two grooves 6 into which the crackers fit at the end of the machine spindle.
Milling cutters with cylindrical landing hole (see Fig. 49, b) is attached directly to the end of the machine spindle using four screws.
The most accurate centering of the cutter on the spindle of the milling machine and, therefore, the least runout of the teeth in operation is ensured by cutters with a conical mounting hole.
Mounting according to fig. 50 is used on vertical and horizontal milling machines, mounting according to Fig. 51 - mainly on longitudinal milling machines, when it is necessary to have a large overhang of the end of the cutter from the end of the spindle.
If a person is interested in carpentry, then he cannot do without a router. They are produced in large quantities and in a wide range. The main thing is to understand how to work with a router.
This tool allows you to solve many issues when renovating an apartment or repairing furniture. It significantly expands a person's ability to work with wood. A wide variety of wooden products can be made with your own hands, with a minimum of effort. Anyone who understands how to work with a router is able to repair and decorate furniture and wooden items interior
When choosing a router, you should pay attention to the working field, optimal size which is 12000x1200 mm.
A milling cutter (or milling machine) is a manual electric tool for processing wooden products by milling method. This method implies curly processing edges of the product, production and processing of grooves and various holes. The main purpose of hand-held specimens is woodworking, but they can be used to work on soft metals and plastics, using special cutters and equipment.
The operating principle of the milling cutter is very simple: the workpiece is processed by rotating the cutting element - the cutter. At the same time, at the same time longitudinal direction move the router itself (when the workpiece is secured) or the workpiece (when secured). A milling cutter is a cutting tool that contains one or more cutting elements (teeth, blades).
Existing tool types
The main types of milling machines: a – cantilever vertical milling machines, 6 – continuous milling machines (rotary milling and drum milling), c – copying (vertical and horizontal) milling machines, d – vertical milling machines without cantilever; d – longitudinal milling machines; f – widely-universal milling machines (cantilever and non-cantilever), g – horizontal cantilever milling machines.
Household hand routers come in three types: top, edge and lamellar. With the help of an overhead router you can perform almost any type of work. It is divided into two designs: submersible and fixed. The submersible type design provides for the movement of the electric motor together with the cutter in the vertical direction along two special guides. The electric motor housing is damped by a spring and it also rests against the workpiece during milling. A fixed milling cutter has a fixed electric motor, and when the depth of processing changes, it must be moved and re-secured. In this design, changing the depth of processing without stopping the rotation of the cutter is impossible.
Other routers have designs that allow only certain operations. Thus, an edging machine is designed for profiling and processing the edges of the workpiece. Lamellar, on the contrary, is not capable of processing edges, but perfectly mills grooves at the ends of the workpiece. Such tools have a narrow focus, but have one big advantage- they are small in size.
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Router design
The top router consists of two main parts: an electric motor and a base, which are interconnected lifting mechanism(guide), allowing you to record different immersion depths of the cutter. The mechanism has an adjusting screw with which you can make fine adjustments. A chuck is attached to the electric motor shaft, with which the cutter is installed.
To ensure the quality of processing, the equipment is equipped with a straight guide that helps move the cutter to the required distance in the plane of the workpiece. Some specimens are also equipped with a circular guide, which helps to make circular movements when processing circles large diameter. To mill a groove, a guide in the form of an angular stop is installed.
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Types of work for a router
Design of a hand router: 1 - base - plywood (acrylic, MDF), 2 - 6 mm cutter, 3 - counter hole in the base of the router, 4 - what should happen, 5 - hairpin (a nail without a head is good).
The router is designed for a wide variety of woodworking jobs. If you work with it correctly, it will not be difficult to create a hole of any shape, make any grooves and grooves. In this case, the holes can have different shapes not only in one cross section, but also different shape one hole in thickness.
An important type of work is edge profiling. Using hand-held household tools you can make cornices, skirting boards, glazing beads, profiled bars for window frames etc. The milling cutter allows you to prepare not only a longitudinal profile different types, but also to create an ornament and a decorative edge on the edges of the workpiece. Such processing, for example, will allow you to create a frame for a picture. If there is not enough experience with a router, then decorative edges are made using a template.
A household router will allow you to perform many jobs around the house. With its help, for example, you can make a groove for a lock in door jamb. Various elements connecting beams during construction is quite feasible with a router. When conducting different types work, you just need to select a universal type of router and install the desired cutter.
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Selecting cutter type
The type of cutter is selected according to the type of milling and the material of the workpiece. When processing soft wood, light metal components are used, and for hard wood, more durable cutters are used. So, for soft wood you can use cutters with high-speed blades of the HSS type, and for hard wood - type HM (carbide).
Another classification divides cutters into bearing and bearingless. Instances without bearings are more versatile, and with their help you can perform almost any processing. A large number of cutters are available with bearings that are mounted flush with the blade on both sides. This design allows you to improve the quality and accuracy of certain types of milling (profile, edge, any edge processing).
According to the type of milling performed, milling cutters are divided into several types. Profile cutters are used for milling the edge of a workpiece to create a profile, decorative protrusions, rounding, etc. Such cutters are often bearing-type. The shape is usually cylindrical. Moulders are usually used to round edges.
Cone-shaped cutters are designed for milling profiles with different angles tilt Angles can be created when processing holes, various cutouts, etc.
Groove (rectangular) are used for the manufacture of rectangular grooves. Milling cutters are available in a wide range of diameters, blade types and lengths. V-shaped cutters are used to make grooves or holes at a 45-degree angle.
Disc cutters are designed for making grooves located in the horizontal direction. This type of work is important when connecting beams to each other during construction, i.e. when forming end connecting elements. For the trapezoidal type of tenons of connection elements, elements of the “swallow’s nest” or “dovetail” type are used.
Specialized cutters are also used: rebated cutters - for milling quarters; fillet - for special (fillet) edge profiling; fitting - for copying a part or adjusting it to the dimensions of an analogue (such cutters are equipped with bearings).
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Installation and fastening of the cutter
In order to start working with a router, you need to install and secure the cutter. After selecting the desired cutter by type and size, it is inserted into the chuck. To do this, the shank is immersed in the cutter chuck to a depth of 20 mm. The cartridge case is turned clockwise until it clicks. Then the nut on the chuck is tightened with a wrench. The cutter is installed and secured.
Before starting milling, you should set the depth of immersion of the cutter into the workpiece. For these purposes, it is necessary to use a movable depth limiter. In this case, the fine adjustment knob should first be installed in the middle, between the “+” and “-” marks.
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Primary requirements
Milling should be carried out without exceeding the rotation speed of the router. It is installed taking into account the type of work and workpiece material. Increasing the diameter of the cutter requires reducing its rotation speed: for a cutter with a diameter of up to 10 mm, the speed can be 20,000 rpm, and for a cutter with a diameter of up to 40 mm - 10,000 rpm. Requirements for setting the rotation speed are usually specified in the instructions for the router.
When working, the router can be held by hand or mounted on a workbench. If the router is fed manually, the workpiece must be securely fastened. When attaching a router, various devices can be used, in which guides should be used to move the workpiece (straight or arcuate). When forming an edge profile, narrow rulers fixed perpendicular to the workpiece should be used as a limiter and guide.
To ensure safety, the following condition must be met: the direction of movement of the router must be opposite to the direction of rotation of the cutter.
If the directions coincide, the tool may be given an unplanned acceleration, which leads to the tool slipping from the hands.
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Working with a hand router
The wooden workpiece is fixed on the workbench so that there is free access to the processing area. The necessary guides for moving the router are fixed (straight, arc-shaped, ruler). The router is held with both hands.
The milling cutter is brought to the surface of the workpiece to be machined so that the cutter rests on the workpiece. By lightly pressing the router, the rotating cutter enters the workpiece to the required depth (to the base of the router). Smoothly moving the router in the desired direction (along the guide), a groove of the required depth and length is made. When forming deep grooves (cuts), the operation should be carried out in several passes. The immersion depth of the cutter in one pass is recommended within 5-6 mm. The router moves only in one direction. For inexperienced milling operators, it is advisable to use router movement limiters and additional guides that are mounted on the workpiece or workbench.
The milling operator must know the type and number of the spindle socket cone of his machine and the mounting dimensions of the front end of the spindle.
The dimensions of the spindle socket cone and the mounting flange of the front end of the spindle of milling machines are standardized by GOST 836-47, and therefore end mills and milling arbors manufactured with a standard shank fit these machines.
In Fig. 59 shows the front end of a milling machine spindle. The inner cone 2, into which the tool shank is inserted, is made very steep. Rotation of the tool is transmitted by drivers 5 inserted into grooves in the end of the spindle and screwed in with screws. The tool, which is mounted directly on the mounting flange 1, is centered by a cylindrical sharpening of the front end and is secured with four screws inserted into holes 4.
Fastening the shear cutters. Shell cutters are mounted on mandrels, which are secured in the machine spindle.
In Fig. 60 shows mandrels having a conical shank Y, which corresponds to the conical socket of the front end of the spindle of domestic milling machines and is centered in it. Recesses 2 in the mandrel flange are put on drivers inserted into grooves at the end of the spindle.
The mandrel shown in Fig. 60, a, is intended for fastening cutters operating under high forces. It has a large length, allowing the use of an additional trunk earring. The mandrel shown in Fig. 60, b, is intended for lighter work.
The mandrels shown in Fig. 60, a and b, are called center. The center mandrel is fixed at one end in the slot of the machine spindle, and the other is supported by the trunk earring bearing.
The mandrel shown in Fig. 60, in, is called an end mill, since one end of it is fixed in the socket of the machine spindle, and at the other end a mounted cutter is installed, which works together with a mandrel, like an end mill.
Fastening cutters to center mandrels. In Fig. 61 shows various cases of attaching shell cutters to center mandrels. The conical shank of the mandrel fits into the conical hole 8 of the spindle, the other end fits into the bearing 1 of the earring.
In Fig. 61, and shows the mounting on a mandrel of a cylindrical cutter 5 with helical teeth. The cutter is put on the middle (working) part of the mandrel and can be installed anywhere on the mandrel using installation rings 3, 4, 6 and 7. These rings are put on the mandrel in the same way as cutter 5. The leftmost ring 7 rests against the shoulder, located on the mandrel, and the rightmost ring 3 is supported by a nut 2 screwed onto the end of the mandrel.
In Fig. 61, b shows the mounting of several cutters on a mandrel close to one another (a set of cutters). It can be seen from the drawing that the width of the mounting rings is different here.
The normal set of mounting rings supplied with the milling machine consists of rings with a width of 1 to 50 mm, namely: 1.0; 1.1; 1.2; 1.25; 1.3; 1.4; 1.5; 1.75; 2.0; 2.5; 3.0 3.25; 5.0; 6.0; 7.5; 8.0;* 10 20; thirty; 40 and 50 mm.
Using mounting rings, the cutters can be secured at a certain distance from each other. In Fig. 61, c shows the fastening of two cutters at a distance A from each other. This distance is established by selecting rings of the required width.
Sometimes, when adjusting the distance between the cutters on the mandrel, it is necessary to place thin spacers made of aluminum or copper foil and even writing or tissue paper between the adjusting rings, since using the rings included in the set it is impossible to obtain the required distance between the cutters.
Innovative milling machine operator V. A. Goryainov designed an adjustable setting ring (Fig. 62), which allows you to quickly ensure the required distance between cutters with an accuracy of 0.01 mm. The distance between the cutters 4 is adjusted by turning the adjustable adjusting ring 6 with a key 5, which has a dial with 0.01 mm graduations. Pre-installation of cutters is carried out using conventional installation rings 3.
Cutters of small diameters, operating with little effort, are kept from turning on the mandrel by frictional forces that arise between the ends of the cutter and the ends of the rings due to tightening with a nut. But during heavy work, this friction is not enough, and the cutter is held on the mandrel using a key. A keyway is milled along the entire length of the middle (working) part of the mandrel; a key is attached to it, onto which the cutter is put. In this case, the rings are also placed on the key.
The diameters of the holes in attachment cutters and rings, as well as the outer diameters of the working part of the milling mandrels, are made only in certain sizes. The following mandrel diameters are accepted at domestic factories: 10, 13, 16, 22, 27, 32, 40 and 50 mm. Keyways and keys are also made in certain sizes, so that the milling cutters, mandrels, rings and keys of the same number available in the tool store will definitely fit each other.
Milling mandrels should not have runout, nicks or dents. There should be no nicks or burrs at the ends of the rings. The ends of the rings must be parallel and perpendicular to the axis of the ring.
When installing cutters, you need to place them as close as possible to the front end of the machine spindle to reduce the load on the mandrel. If for some reason this fails, then an additional shackle must be installed, which relieves the load on the milling mandrel. The procedure for installing and securing the cutter on the mandrel and securing the mandrel in the slot of the machine spindle is described in detail when considering setting up the machine.
Fastening cutters to end mandrels. Clamping of end mills and disk cutters, which do not require a large reach, are produced on end mandrels.
In Fig. 63 shows the end mandrel. The conical end 1 is inserted into the conical socket of the machine spindle. The cutter is put on the cylindrical part of the mandrel and tightened with screw 3. Key 2 prevents the cutter from turning on the mandrel.
Fastening cutters with conical and cylindrical shanks. Cutters with a conical shank, the size of which coincides with the dimensions of the conical socket of the spindle, are inserted with the shank into the spindle and secured in it using a tightening screw (ramrod). This is the easiest way to secure a cutter on both horizontal and vertical milling machines.
If the size of the cutter shank cone is smaller than the size of the spindle socket cone, then they resort to adapter bushings (Fig. 64). The outer cone of such a bushing corresponds to the slot of the machine spindle, and the inner cone corresponds to the shank of the cutter. The adapter sleeve with the inserted cutter is installed in the spindle and tightened using a tightening screw (ramrod).
The cutters with a cylindrical shank are secured using the chuck shown in Fig. 65. The cutter is inserted into the cylindrical hole of the expanding collet of the chuck 1 and secured by means of a nut 2 located at the front end of the chuck and enclosing the expanding sleeve 3 with its shoulders. The chuck with the cutter on is installed in the spindle of a horizontal or vertical milling machine and secured with a tightening screw. The cutter is removed after releasing nut 2.
Fastening of large-diameter sheath cutters. Prefabricated end mills with a diameter of 80 mm and above are manufactured with attachments.
The mounting holes of such cutters are made conical or cylindrical.
Milling cutters with a conical mounting hole (Fig. 66, a) are placed on the cone 1 of a special milling mandrel (Fig. 66, b) and secured to it using liner 2 and screw 3. The insert 2 fits into the grooves 4 in the cutter body. The mandrel with the cutter is secured in the conical socket of the spindle using a tightening screw (ramrod) by screwing it into the threaded hole 5 of the mandrel. To prevent the milling mandrel from turning in the conical seat of the spindle, the mandrel has two grooves 5 that fit into the cracks 3 at the end of the front end of the machine spindle (see Fig. 59).
Cutters with a cylindrical mounting hole (Fig. 67) are mounted on the cylindrical end of 1 spindle (see Fig. 59) and attached directly to its end using four screws that fit into the corresponding threaded holes in the end of the spindle.
Face milling cutters designed for processing planes on vertical and horizontal milling machines. Face mills, unlike cylindrical ones, have teeth located on the cylindrical surface and at the end.
Face mills are divided into mounted (GOST 9304-69) with fine teeth and with large teeth and mounted with insert knives in accordance with GOST 1092-69.
The main dimensions of end mills are: diameter - D, cutter length - L, hole diameter - d and number of teeth - z.
Face milling cutters have a number of advantages over cylindrical ones, the main ones being:
- more rigid mounting on the mandrel or spindle;
- smoother operation due to large number simultaneously working teeth.
Therefore, in most cases it is advisable to process planes using end mills.
Face milling cutters, like cylindrical ones, are divided into right-hand and left-hand cutting.
Right-handed cutters are those that must rotate clockwise during operation (Fig. 45, a), and left-handed cutters - counterclockwise (Fig. 45, b), if you look at the cutter or milling head crest (when working on a vertical milling machine). machine).
End mills equipped with carbide inserts are widely used. Milling planes with carbide end mills is more productive than milling with cylindrical cutters.
IN Lately End mills with non-sharpening carbide inserts have become widespread.
Setting up and configuring the machine to perform various works . When working on vertical and horizontal milling machines with face mills, setup and tuning are fundamentally no different from setting up and tuning a horizontal milling machine when working with cylindrical cutters. Therefore, we will only focus on distinctive features adjustments and adjustments when milling with end mills.
Installing and securing end mills on vertical milling machines. Depending on the type of cutter used, mounting it on a vertical milling machine can be done in several ways:
Face milling cutters with a calibrated through hole are centered along the cylindrical part of the mandrel 3 with a conical part, installed in the conical hole of the spindle and secured in it with a cleaning rod 7 and a nut 2 (Fig. 46, a). The base end of the cutter rests on one of the ends of the adapter flange 4, the second end of which rests on the end of the mandrel 3. The tenons of the spindle 6 fit into the grooves of the adapter flange, and the protrusions of the flange into the grooves of the cutter, transmitting torque from the tenon to the cutter. The cutter is secured to the mandrel with screw 5 using a special key.
Rice. 46. Installation of cutters on machines
End mills with a centering groove (Ø 128.57A) are installed directly on the spindle head and secured to it with four screws 7 (Fig. 46, b). The tenons of spindle 2 fit into the grooves of the cutter body, transmitting torque from the spindle to the cutter.
Face mills with a conical shank with a nominal size of the largest cone diameter Ø 59.85 mm and a taper of 7:24, made integral with the cutter body, are inserted into the conical hole of the spindle, secured in it with a ramrod 7 and a nut 2 (Fig. 46, c) . The torque is transmitted by 3 spikes that fit into the grooves of the cutter body.
Face mills that have a through calibrated hole and grooves in the body, the width corresponding to the size of the spindle tenons, are installed on a mandrel fixed in the machine spindle. The cutter is secured to the mandrel with screw 7. Torque is transmitted by spikes 3 that fit into the grooves of the cutter body (Fig. 46, d).
End mills having a Morse taper shank and threaded hole, centered in the adapter sleeve 7, inserted into the conical hole of the spindle and secured with a cleaning rod 2 and a nut 3. The tenons of the spindle 4 fit into the grooves of the adapter sleeve, transmitting torque from the spindle to the cutter (Fig. 46, e).
Setting up vertical milling machines the corresponding cutting modes are performed in the same way as setting up horizontal milling machines.
Selecting the type and size of cutter. The standard stipulates that the parameters of end mills are uniquely defined, i.e., each end mill diameter corresponds to a certain value of the cutter length L, hole diameter d and number of teeth z.
The diameter of the end mill is selected depending on the milling width t according to the formula
D = (0.6 + 0.8)t
For roughing, end mills with insert knives or large teeth are chosen. When finishing, you should use end mills with fine teeth.
However, in all cases, preference should be given to end mills equipped with hard alloys, since the machine processing time in this case is significantly reduced by increasing the cutting speed.
Let's consider setting up a 6P82 horizontal milling machine or a 6P12P vertical milling machine for rough milling of the same workpiece made of steel 45 (σ 75 kg/mm 2), milling width t 75 mm, cutting depth B = 5 mm.
In this case, we will choose an end mill with T15K6 hard alloy inserts. Cutter diameter D = 150 mm, z = 6. Geometric parameters: γ = 5°, α = 6°. Feed per tooth s: selectable within 0.1-0.3 mm/tooth. With a cutting depth B of 5 mm and s z = 0.2 mm/tooth, the cutting speed according to the standards for cutting conditions is v = 250 m/min.
The spindle speed can be easily determined from the graph (see Fig. 40). The graph shows that with D = 150 mm and v = 250 m/min, the nearest machine speed level will be n = 500 rpm. Now, using the nomogram (see Fig. 41), we determine the nearest minute feed available on the indicated cantilever milling machines s = 630 m/min.
Direct calculation gives approximately the same result:
s m = s z z n = 0.2 500 = 600 mm/min.
The nearest minute feed rate will be 630 mm/min.
So, comparing the values of minute feeds when milling with a cylindrical cutter from high speed steelР6М5: s m 250 mm/min and s m 630 mm/min - when milling with an end mill with T15K6 hard alloy inserts, we see that the minute feed in the latter case is 2.4 times greater. The machine processing time for the same part is reduced by the same amount when milling with a carbide end mill. When rough milling the same workpiece made of gray cast iron, it is necessary to take a cutter equipped with hard alloy plates VK8 and VK6. Geometric parameters of the cutter: γ = 0°; α 6-8°. The feed per tooth is correspondingly greater than when processing steel (sz = 0.2-0.6 mm/tooth), the cutting speed is significantly lower than when processing steel, namely, v = 50-130 m/min.
When finishing milling steel and cast iron with carbide cutters, to obtain a surface of a higher roughness class, the feed per tooth is reduced, and the cutting speed is correspondingly increased depending on the grade of the material being processed, the grade of the carbide and other processing conditions.
Setting an end mill to the depth of cut when working on a vertical milling machine is no different from the previously discussed case of installing a cylindrical cutter to the depth of cut.
When milling with an end mill on a horizontal milling machine (Fig. 47), the following procedure is used to set the milling depth.
Rice. 47. Milling the ends with a milling cutter on a horizontal milling machine
Turn on the machine and spindle rotation and, using the longitudinal, transverse and vertical feed handles, carefully bring the workpiece to the cutter until it touches lightly. Use the longitudinal feed handle to move the workpiece out from under the cutter and turn off the spindle rotation. Use the cross feed handle to move the table in the transverse direction by an amount corresponding to a cutting depth of 3 mm. After setting the cutter to the required cutting depth, lock the table console and cross-feed slide, install the cams for turning on the mechanical feed. Then, by smoothly rotating the longitudinal feed handle, bring the workpiece to the cutter without touching it, turn on the spindle, turn on the mechanical feed, mill the plane, turn off the machine and measure the processed workpiece
When milling with carbide end mills at high cutting speeds, attention must be paid to compliance with safety regulations. In such cases, you should use protective screens or safety glasses to prevent facial burns or eye damage from hot chips.
Milling inclined planes and bevels. Inclined planes and bevels can be milled with end mills on vertical milling machines, placing the workpieces at the required angle, as when processing with cylindrical cutters, using a universal vice (Fig. 48, a), rotary tables or special devices(Fig. 48, b). Milling inclined planes 1 and bevels with end mills 2 can also be done by turning the spindle rather than the workpiece. This is possible on vertical milling machines, in which the milling head with spindle rotates in vertical plane, for example, like on machines 6Р12, 6Р13 (see Fig. 17), as well as on widely universal machines like 6Р82Ш, in which the vertical head can be rotated in the vertical and horizontal planes.
Rice. 48. Milling an inclined plane with end mills
Milling inclined planes and bevels with end mills can be done using an overhead vertical head.
The overhead vertical head is a special accessory of a horizontal milling machine.
In Fig. 49, a shows one of the designs of the overhead vertical head, and in Fig. 49, b - various spindle positions. Housing 2 (Fig. 49, a) of the overhead head is installed on the vertical guides of the machine bed and secured with bolts U. Spindle 5 rotates in the rotating part 6 of the head. By releasing the bolts connecting the rotating part 6 of the head to the body, the spindle can be rotated in a vertical plane and at any angle on scale 4.
Rice. 49. Overhead vertical head
Ring 3 is used to remove the head. Rotation from the machine spindle to the head spindle is transmitted using a pair of cylindrical gears 7 and 8. Wheel 8 is mounted with a conical shank on the spindle of a horizontal milling machine, it transmits rotation from the machine spindle to wheel 7, and then through a pair of bevel wheels to the spindle 5 of the overhead vertical head. A cutter is installed into the conical hole of spindle 5. Using a pair of bevel gears, the spindle of the overhead head can be rotated 360° around the machine spindle, and therefore the cutter can be installed at any angle to the table plane (Fig. 49, b). The presence of an overhead vertical head significantly expands the technological capabilities of horizontal milling machines.
Checking the runout of end mills. The scheme for checking the runout of the teeth of end mills is similar to that discussed earlier (see Fig. 38).
Runout of main and auxiliary cutting edges should not exceed the values indicated in the table.
The simplest way is direct installation cutters on a spindle with a nut clamping it. The direction of the thread must be opposite to the direction of rotation of the spindle.
Chucks are used to install end mills on the spindle. Backed cutters are secured with a shank in a collet chuck. Single-cut, non-backed cutters are secured in special chucks with a screw.
When directly seated on the spindle (Fig. A) cutter 3 rests against the shoulder of spindle 7 and is clamped with nut 5. To change the position of the cutter in height, spacer rings 2, spacers or washers 4 are used.
If the diameter of the mounting hole is larger than the diameter of the spindle, use a landing on the spindle through a bushing (Fig. b). The cutter is first secured to sleeve 1 with nut 2, and then the sleeve is installed on the spindle and secured with a tightening nut.
In the case where the spindle does not have a thread for attaching the cutter, use a collet mandrel (Fig. V). The mandrel has an inner conical split 1 and an outer 2 bushings. The cutter is installed on the outer sleeve and secured with a nut. Then the mandrel with the tool is installed on the spindle and secured by rotating the upper tightening nut. In this case, the outer bushing moves along the inner conical bushing, as a result of which its split part tightly covers the spindle.
If the machine spindle does not have axial adjustment movement, the cutter can be mounted in a setting head equipped with a device for adjusting the position of the cutter relative to work surface table (Fig. G). The position of head 2 with the cutter is adjusted with the inner sleeve loosened by rotating screw 1, which rests against the end of the spindle.
Standard fastening is common (Fig. d) of the cutter head on a horizontal spindle with two short conical collets 3, clamped with nuts 1. Pins 4 in the head body fit into the slots of the collets, preventing their rotation. When screwed in, guide screw 2 fits into the keyway of the spindle and serves to fix the head and increase the reliability of torque transmission.
In foreign models of machine tools, hydroplastic devices for securing cutters on spindles have become widespread (Fig. e). Thin-walled bushing 2 is pressed into the cutter body 3. Inner surface The bushing is both centering and clamping. Hydroplastic 4 is injected into the cavity between the sleeve and the cutter under pressure. The pressure is created by rotating the plunger screw 5. To detach the cutter, the pressure in the cavity is reduced by unscrewing the screw 6. The fastening ensures increased accuracy of centering the cutter on the spindle 1.
Methods for attaching the milling cutting tool on machine spindles:
Backed end mills are mounted in collet chucks, non-backed end mills are mounted in special chucks with eccentricity e axis of the tool hole relative to the axis of the chuck shank (Fig. and). The cutter 2 is held in the chuck body 3 by screw 1. The chuck shank 5 is installed in the tapered hole of the spindle 6 and tightened with a nut 4. The chuck body has six holes for screwing in balancing screws.
