LAB #6

Kinematic calculation and construction of the structural grid of the gearbox of a horizontal milling machine mod. 6Р82.Design features

Features of the main components and mechanisms of the machine

Objective:

1. Get acquainted with the layout and main components horizontal - milling

Machine mod. 6P82.

2. Learn to perform kinematic calculation and building structural

grids speed boxes of a horizontal milling machine mod. 6P82.

Work order:

Read the description " Lab work».

Milling represents a type of cutting with a tool called a milling cutter. cutter is a cutting tool with several teeth, each of which is a simple cutter. The milling cutter, during rotation, cuts its teeth into the workpiece advancing on it and with each tooth cuts chips from its surface. After the end of the pass, the cutter is removed from surface to be treated workpiece layer of metal. The surface obtained after the passage of the cutter is called surface treated . The surface formed on the workpiece being machined directly cutting edge cutters, called cutting surface.

Depending on the location of the axis of the cutter relative to the surface being machined, milling is distinguished cylindrical cutter and end cutter. The rotational movement of the cutter is called main movement , and the translational movement of the workpiece - feed motion . Both of these movements must be carried out by a milling machine. The main movement, i.e., the rotation of the cutter, is determined by the number of revolutions of the machine spindle per minute, the feed is determined by the magnitude of the minute movement of the machine table with the workpiece fixed to it relative to the cutter.

Processing schemes blanks on machines milling group (Fig. 1) include the processing of both planes and shaped surfaces.

1. Horizontal planes milled on horizontal milling machines with cylindrical cutters (Fig. 1, a) and on vertical milling machines with end mills (Fig. 1, b). It is expedient to process horizontal planes up to 120 mm wide with cylindrical cutters. In most cases, it is more convenient to process planes with face mills due to the greater rigidity of their fastening in the spindle and smoother operation, since the number of simultaneously working teeth of a face mill is greater than the number of teeth of a cylindrical cutter.

2. Vertical planes milled on horizontal milling machines with end mills (Fig. 1, in) and face milling heads, and on vertical milling machines with end mills (Fig. 1, G).

3. Inclined planes milled face (Fig. 1, e) and end mills on vertical milling machines, in which the milling head with the spindle rotates in a vertical plane. Inclined planes of small width are milled on a horizontal milling machine with a single-angle disc cutter (Fig. 1, e).

4. Combined surfaces milled with a set of cutters (Fig. 1, g) on horizontal milling machines. The accuracy of the relative positions of the machined surfaces depends on the rigidity of the attachment of the cutters along the length of the mandrel. For this purpose, additional supports (suspensions) are used, the use of cutters that are disproportionate in diameter is avoided (the recommended ratio of cutter diameters is not more than 1.5).

Rice. 1. Schemes for processing workpieces on milling machines

Rice. 2. Horizontal milling machine mod. 6P82:

1-base; 2 - bed: 3 - console; 4-sled 5-table;

Spindle: 7 - trunk

Rice. 3. Kinematic diagram of a horizontal milling machine mod. 6Р82

5. Ledges and rectangular slots milled end (Fig. 1, h) and disk (Fig. 1, and) cutters on vertical and horizontal milling machines. Ledges and grooves are best milled with disc cutters, as they have a larger number of teeth and allow high cutting speeds.

6. Shaped grooves milled with a shaped disc cutter (Fig. 1, to), corner grooves - one-angle and two-angle (Fig. 1, l) cutters on horizontal milling machines.

7. V-groove milled on a vertical milling machine in 2 passes: rectangular groove end mill, then groove bevels - single-angle cutter (Fig. 1, m).

8. T-slots (Fig. 1, n), which are widely used in mechanical engineering as machine grooves, for example, on the tables of milling machines, they are milled in 2 passes: first, the groove rectangular profile - with an end mill, then the lower part of the groove - with a cutter for T-slots .

9. Keyways milled with end or keyway (Fig. 1, about) milling cutters on vertical milling machines. The accuracy of obtaining a keyway is an important condition for milling, since the nature of the fit on the key of the parts mating with the shaft depends on it. Milling with a key cutter provides a more accurate groove; when regrinding along the end teeth, the diameter of the key cutter practically does not change.

10. Shaped surfaces of an open contour with a curved generatrix and a straight guide, they are milled on horizontal and vertical milling machines with shaped cutters of the corresponding profile (Fig. 1, P). The use of shaped cutters is effective when processing narrow and long shaped surfaces. Wide profiles are processed with a set of shaped cutters.

11. Horizontal, vertical, inclined planes and grooves simultaneously processed on longitudinal milling two-column machines with face and end mills with the movement of the longitudinal feed of the table, on which the body workpiece is fixed in the fixture (Fig. 1, R).

12. Horizontal planes according to the method of continuous milling, they are processed on rotary milling machines with end mills (Fig. 1, with). The workpieces are installed in fixtures evenly spaced around the circumference of the table, and they are informed of the movement of the circular feed. The workpiece is first roughed (dimension H 1 ), and then the cutter installed in the second spindle is finished (size H g ).

13. Spatially complex surfaces processed on copy-milling semiautomatic devices (Fig. 1, t). Processing is carried out with a special end mill. Milling is carried out along 3 coordinates: x, y, z (3D milling).

To study the purpose of the main nodes horizontally - milling machine mod. 6Р82

(Fig. 2). Run layout sketch machine with indication of the main components.

3. Design technological adjustments processing parts on horizontal milling

machines (according to Fig. 1).

4. Build kinematic diagram gearboxes (Fig. 3) of the machine mod. 6Р82

(width of gears at least 5 mm, Ǿ minimum gear at least 15 mm).

5. Build structural grid gearboxes of the machine mod. 6Р82 (width and

height not less than 120 mm).

Horizontal milling machines

On fig. 20 shows the main components of a horizontal milling machine type 6M82G manufactured by the Gorky Plant of Milling Machines. The machine belongs to the second dimensional range, however, in terms of design it is similar to the horizontal milling machine 6M83G, which belongs to the third dimensional range. The production of machine tools of the M series was mastered in 1960; they are often found in the workshops of our factories. A good knowledge of the 6M82G machine makes it possible to quickly master the work on horizontal milling machines of other types, since their main components differ little from the components of this machine.
All components and parts of the machine are interchangeable with the exception of wedges and some guides that are scraped.
Machine 6M82G outwardly differs from the previously produced model 6N82G only in the presence of a longitudinal feed handwheel on the front side of the table, it has a slightly different range of spindle speeds and table feeds.

The base of the machine is cast in gray cast iron and is precisely cut on both sides. On one side of the base, the machine bed is installed and bolted; the other side is adjacent to the floor of the workshop. At the base there is a trough for coolant, which flows down the tubes from the table. An electric pump for supplying coolant from the trough to the tool is mounted on the base.
The bed serves for fastening of all knots and mechanisms of the machine. Some machine components (speed box, spindle, belt-driven electric motor, motion transmission mechanism to the feed box) are located inside the bed and are not visible. Other machine components (console, feed box, trunk, table, coolant pump) are located on the outer surfaces of the bed.
The bed is box-shaped and reinforced inside with ribs; on its front wall there are vertical guides (made in the form of a dovetail) for the console, and at the top - horizontal guides for the trunk.
The trunk is available for horizontal and universal milling machines and serves to correct installation and milling mandrel support. The trunk is installed in horizontal guides on the upper part of the bed and can be fixed at any distance from its mirror, i.e. with a different reach (see Fig. 10). To increase rigidity when machining heavy parts and for large cross-sections of chips, supports are used that connect the trunk to the console.
The console is a rigid iron casting mounted on vertical bed rails. The console moves along the vertical guides of the bed and carries the horizontal guides for the sled. It is supported by a post that has a telescoping screw to raise and lower the console. The rigidity of the console structure and the accuracy of its guides are of paramount importance for. machine work. The console has two bolts that fasten the supports that connect the machine table with the trunk for better stability under heavy loads.
The slide is an intermediate link between the console and the machine table. The table moves along the upper slide rails in the longitudinal direction, and the lower part of the slide moves in the transverse direction along the upper console rails.
The table is mounted on guide rails and moves in the longitudinal direction. Workpieces, clamping and other devices are fixed on the table, for which working surface The table has longitudinal T-slots.
The movements of the table, slide and console inform the workpiece of longitudinal, transverse and vertical feeds in relation to the cutter.
Console milling machines usually have both manual and mechanical feed of the table, sled and console.
For installation movements during setup and for idle runs of the table, manual or mechanical feed is used, and for working feeds, only mechanical feed.
In addition to working feeds, the table usually has a rapid move (rapid movement) in all three directions - for bringing the workpiece to the cutter, as well as for reverse movement.
The fast stroke is carried out at one constant speed, and the working feeds have several steps, which can be set using the feed box, depending on the machining, cutter material and workpiece.
Spindle . To rotate the cutting tool, a spindle is used, which receives movement from the gearbox. The accuracy of rotation of the mandrel with the milling cutter depends on the accuracy of the spindle manufacturing, its strength and rigidity. The spindles of milling machines are made of 40Xi alloy steel and subjected to heat treatment.

On fig. 21 shows the spindle of the 6M82G machine. The spindle has three roller and ball bearings. The front end of the spindle and the conical seat are very precisely machined - places for installing and fixing the tool and mandrel.
The front end of the spindle of the milling machine 6M82G is shown in fig. 22. The inner cone 2, into which the milling mandrel is inserted, is made very steep. The rotation of the milling mandrel is carried out by leashes 3, which are inserted into the grooves in the end of the spindle and screwed on. The milling heads are fixed with screws screwed into holes 4 and centered with the front part 1 of the spindle. Sometimes a special mandrel is used for centering, one end of which enters the conical socket of the 2nd spindle, and the milling head is mounted on the other.

Domestic milling machines have a standard front end of the spindle (Fig. 22).
The spindle is rotated by an electric motor located in the machine frame, through a pulley, a belt drive and then through a gearbox. The engine is located inside the bed, which increases the safety of work and reduces the area occupied by the machine.
Gearbox designed to transfer rotation from the pulley to the spindle and to change the number of its revolutions by switching gears.
The table feed drive is carried out from an electric motor located in the machine console through the feed box.
The feed box is used to change the feed of the table in the vertical, longitudinal and transverse directions.
Console milling machines of modern design, like the 6M82G machine, have separate electric motors for driving the gearbox and feed box.
On fig. 23 shows a horizontal milling machine 6N81G produced by the Dmitrovsky plant of milling machines. It belongs to the first dimension range. All its main components and mechanisms (base, frame, trunk, console, table) are similar to those discussed above. The only difference is that the rotation of the spindle is communicated through a belt drive from the gearbox pulley, rigidly connected to the main drive electric motor. In addition, the spindle is equipped with gear enumeration, which allows to have high and low spindle speeds.

Vertical milling machines

A vertical milling machine differs from a horizontal one only in the location of the spindle, therefore everything stated above about a horizontal milling machine is applicable to a vertical milling machine, with the exception of those parts and assemblies that the latter does not have (trunk, supports).
On fig. 24 shows the main components of a vertical milling machine type 6M12P manufactured by the Gorky Plant of Milling Machines.

Machines of this model, together with a horizontal milling machine 6M82G (see Fig. 7) or a universal milling machine 6M82 (see Fig. 8), form a range of cantilever milling machines of the 2nd size.
All machines of the 2nd size range have 18 spindle speeds in the range of 31.5-1600 rpm and 18 feed steps ranging from 25 to 1250 mm/min for longitudinal and transverse movements of the table and from 8.3 to 400 mm/min- for vertical. The rapid travel of the table in the longitudinal and transverse directions is 3000 mm/min, and for vertical - 1000 mm/min. Size 3 machines have the same speeds, cutting feeds and rapid traverse.
The working surface of the table for machines of the 2nd size - 320X1500 mm mm):

The working surface of the table for machines of the 3rd size is 400X2000 mm. The table has the following maximum mechanical movements (in mm):

On fig. 25 shows the main components of a 6H11 vertical milling machine manufactured by the Dmitrov Milling Machine Plant. Machines of this model, together with horizontal milling machines 6N81G (see Fig. 23) and similar universal milling machines 6N81, form a range of console milling machines of the 1st size.
All machines of the range of the first size have 16 spindle speeds ranging from 65 to 1800 rpm and 16 table feed steps ranging from 35 to 980 mm/min for longitudinal movement, from 25 to 765 mm/min for transverse and from 12 to 830 mm/min for vertical; high speed - respectively 2900, 2300 and 1150 mm/min.
The working surface of the table for machines of the first size, as mentioned earlier, is 250X1000 mm. The table has the following maximum mechanical movements (in mm):

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Milling machines are designed for processing external and internal flat, shaped surfaces, ledges, grooves, straight and helical grooves, splines on shafts, cutting gears, etc.

The designs of milling machines are diverse. They produce universal, specialized and special milling. The main shaping movements are the rotation of the cutter (the main movement) and the feed movement, which is reported to the workpiece or cutter. The drives of the main movement and feed are performed separately. Auxiliary movements associated with the supply and withdrawal of the workpiece to the tool are mechanized and carried out from the drive of rapid movements. The main elements of the mechanisms of machine tools are unified. The main parameter characterizing milling machines general purpose, is the size of the working surface of the table.

In general, milling machines can be divided into two main groups: 1) general purpose or universal (vertical milling, horizontal milling, longitudinal milling); 2) specialized and special (slotted milling, keyway milling, carousel milling, copy milling, etc.). According to their design features, these machines are divided into

A - universal console horizontal milling, b - wide universal console horizontal milling, c - wide universal consoleless milling, d console vertical milling, d - consoleless vertical milling, e - consoleless horizontal milling, g - longitudinal milling, h - carousel-milling, and - drum-milling - ny

On console (the table is located on a lifting bracket-console), consoleless (the table moves on a fixed bed in the longitudinal and transverse directions) and continuous action (carousel and drum).

In a single, small - and medium-scale production, console milling machines are most common. Universal con-

The solo horizontal milling machine (Fig. 119, a) has a horizontal spindle 2 and a retractable trunk 7, on which the earring J is installed, supporting the mandrel with a cutter, the console 4 moves along the rack guide 5. On the console there are sleds 6 and table 7.

Widely universal cantilever horizontal milling machine (Fig. 119; b), in addition to the horizontal spindle, has a spindle head 7, which can be rotated on the trunk in two mutually perpendicular directions, so that the spindle with the cutter can be installed at any angle to the table plane and to the workpiece being processed . On head 1, an overhead head 2 is mounted, designed for drilling, reaming, countersinking, boring and milling.

The console vertical milling machine (Fig. 119, d) has a vertical spindle J, which is located in the rotary spindle head 2 mounted on the rack 7. Consoleless vertical and horizontal milling machines (Fig. 119, e, e), which serve to processing of workpieces of large parts, have a slide 2 and a table 3 that move along the guides of the bed 7. The spindle head 5 moves along the guides of the rack 6. The spindle 4 has axial movements when the cutter is installed.

Longitudinal milling machines (Fig. 119, g) are designed for processing workpieces of large parts. Two vertical posts 6 are installed on the frame /, connected by a cross member 7. Milling heads J with horizontal spindles and a traverse (cross member) 4 are mounted on the guide posts. Milling heads 5 with vertical spindles are installed on the latter. Table 2 moves along the rails of racks 4.

Carousel milling machines (Fig. 119, h), designed for surface treatment with face mills, have one or more J spindles for finishing and roughing. The spindle head 2 moves along the guides of the rack 1. The table 4, rotating continuously, informs the feed rotation of the workpieces installed on it. A table with a slide 5 has an installation movement along the frame guides 6. Drum-milling machines (Fig. 119, and) are used in large-scale and mass production. The blanks are mounted on a rotating drum 2 having a feed motion. Milling heads 3 (for roughing) and 1 (for finishing) move along the guide rails 4.

Shirokouniversalny cantilever horizontal milling machine mod. 6R82Sh. The machine is used to perform various milling work, as well as drilling and simple boring work in workpieces made of cast iron, steel, non-ferrous metals. The machine can operate in semi-automatic and automatic modes, which enables multi-machine maintenance. On fig. 120, 121, 122 shown

Respectively general form, the main components and the kinematic diagram of this machine.

Technical characteristics of the machine. The size of the working surface of the table (length x width) 1250 x 320 mm; the greatest movement of the table: longitudinal - 800 mm, transverse - 240 mm, vertical - 360 mm; the number of speed steps of the spindle 18; spindle speed limits 31.5-1600 min "1; number of table feeds 18; longitudinal and transverse feed limits 25-1250 mm / min, vertical - 416.6 mm / min; machine dimensions 2305 x 1950 x 1680 mm; weight 2830 kg.

Machine kinematics. The drive of the horizontal spindle (main movement) is carried out by an electric motor Ml through gear pe - 208

Redachi. The number of speed steps is equal to the number of gear ratio options from the electric motor to the spindle, i.e. 3 x 3 x 2 = = 18. Minimum speed n^ = 1460 [(27/53) x (60/38) x x(17 / 46) x (19/69) \u003d 31.5 min "1; maximum ptah \u003d 1460 x (27/53) x x (22/32) x (38/26) x (82/38) \u003d 1600 min1.

The swivel head spindle is driven by an M2 motor through gears. Number of rotation steps 2x3x2=12; lp1і11 \u003d 1430 x (28/72) x (34/66) x (21/59) x (28/28) x (19/19) \u003d \u003d 1600 min "1.

The table feed drive in the transverse and longitudinal directions is carried out through gears from the MZ electric motor. Minimum table feed fc in the indicated directions 35) x (18/33) x x (33/37) x (18/16) x (18/18) x 6 = 25 mm/min, L^x = 1430 x (26/50) x (26/ 57) x x (36/18) x (24/24) x (40/40) x (28/35) x (18/33) x (33/37) x (18/16) x (18/18) ) x xb = 1250 mm/min.

Rapid feed of the table in the longitudinal and transverse directions =3000 mm/min.

Maximum table feed in vertical direction<5вшах =1430 х (26/50) х (26/57) х (36/18) х (24/34) х (40/40) х (28/35) х (18/33) х х(22/33) х (23/46) х 6 = 1000 мм/мин.

The speed box of the spindle drive of the rotary head 6 moves along the guides of the frame 1 (Fig. 121) by rotating the flywheel 75 (Fig. 120) with the clamp 39 released.

The gearbox of the horizontal spindle is located in the frame and is connected to the motor shaft by a flexible coupling. The spindle 11 of the machine (Fig. 123) is mounted on bearings 4, 2, 12. The axial clearance in the spindle is adjusted by grinding the rings 9.10. The increased clearance in the bearing 4 is eliminated by grinding the semi-rings 5 ​​and the nut 1 as follows. Remove cover 3 (or side cover), flange 6, spring ring 7, rings 8 and take out half rings 5. Use nut 1 to select the gap so that during operation the heating of the bearings does not exceed 60 ° C. Measure the gap between the bearing and the spindle shoulder and in in accordance with this, half-rings 5 ​​are ground. Then half-rings are installed, parts 6, 8, 7, 3 are mounted.

The speed change box (Fig. 124) provides a choice of the required speed without successive passage of intermediate steps. The rail 1 (Fig. 124, a), moving through the handle through the gear sector 2 and the fork 10 (Fig. 124, b), moves the main roller 3 with the switching disk 9 in the axial direction using the gear wheel 2 and the bushing 4. On the disk several rows of holes are made, located opposite the pins 8 of the rails 5 and 7, connected in pairs with the wheel 6. A shift fork is attached to one of each pair of rails. The rails move when the disc is pressed against the pins. At the end of the disk stroke, the forks take up a position corresponding to the engagement of certain pairs of gears. When choosing speeds, the limb is fixed by ball 1 (Fig. 124, b), which falls into the grooves of sprocket 11. Handle 5 (Fig. 124, a) is fixed when turned on by ball 3 and spring 4; in this case, the spike of the handle enters the groove of the flange.

The swivel head (Fig. 125) is mounted on the trunk through the intermediate plate by means of bolts included in the annular T-slot and centered in the annular groove. Spindle 8, mounted in a retractable sleeve 9, receives rotation from the gearbox through the cam clutch 1 and bevel wheels 4, 2 and 5, 4. Wheels 7 and 3 are used to adjust the axial clearance in the bearings and spindle, and half rings 2 and nut 6 - for eliminate play in the front bearing. The extension of the sleeve is carried out with a handwheel.

The overhead head (Fig. 126) is mounted on the swivel head with bolts included in the T-slot and rigidly fixed. Spindle 5 receives rotation from spindle 1 of the swivel head through bevel gears 3, 4. Nut Adjust the clearance in the spindle bearings.

The feed box (Fig. 127, a) provides working feeds and installation movements of the table, sled and console by switching 2-S

Blocks of gears and transmission of rotation to the input shaft B through a ball safety clutch, a cam clutch 4 and a sleeve 3 connected with a key to the clutch 4 and shaft B. The stopper 1 rigidly fixes the position of the nut 15. When the feed mechanism is overloaded, the balls in contact with the clutch hole 2, compress the springs and come out of contact. The wheel 14 then slips relative to the clutch 2, and the working feed stops.

Fast rotation is transmitted from the electric motor (bypassing the gearbox) to the gear wheel C, which is mounted on the shank of the friction clutch housing 9 and has a constant speed. Nut 10 must be tightened. Housing 9 rotates freely. The friction disks are connected (through one) to the housing 9 and the sleeve 12 connected to the shaft B. When the clutch 4 is pressed on the end

Bushings 5 ​​and then on the nut 11 discs 7 and 8 are connected and transmit rapid rotation to the shaft B and gear A. The force of compression of the discs

7 and is adjusted using pin 6. The movement from shaft B to the driven shaft is carried out through a cam clutch 13.

The feed switching mechanism (Fig. 127, b) is included in the feed box assembly. The principle of operation of the mechanism is similar to the operation of a gearbox. Roller 1, when turned on, is locked by balls 6 and bushing 2, which prevents displacement of disk 9 in the axial direction. When you press the ^ button, the balls fall into the annular groove

Roller 3 and roller 7 are released from fixation. The switching disk 9 is fixed from rotation by the ball 8 through the bushing 5 connected with the key to the ball 7. The screw 7 adjusts the spring tension.

The console (Fig. 128) combines the nodes of the feed chain of the machine. Shafts and gears are mounted in it, transmitting movement from the feed box in three directions (to the screws of the longitudinal, transverse and vertical feeds); mechanism for switching on transverse and vertical feeds. The gear wheel 8 rotates from the wheel A (Fig. 127, a) and transmits the movement to the gear wheels 7, 4, 2, 1 (Fig. 128, a). Wheel 8 can transmit movement to the shaft only through the cam clutch 6. Further, through cylindrical and bevel gears, the movement is transmitted to the screw 16 (Fig. 128, b). The engagement of pairs 16 and 10 is adjusted by compensators 14, 15 and fixed with a screw entering pin 13. Sleeve 77 is not dismantled, the vertical movement nut is fixed in the column. Wheel 2 through the key and splines rotates the shaft IX of the chain of the longitudinal stroke. The screw X of the transverse feed rotates from wheel 2 and wheel 7 freely sitting on the shaft with the transverse clutch engaged. Shafts XII and XIII are dismantled when the stoppers are removed from the wheels 8, 9.

The sled is dismantled after shaft Щ is removed, for which it is necessary to remove the upper shield on the console guides, knock out pin 3 and remove shaft IX. The mechanism for turning on the installation movements (Fig. 129) turns on the clutch and compresses the friction clutch discs. The lever 7 is pinned on the axis 4. The latter is pressed in the direction of the bed mirror by the spring 6. The right nuts 2 serve to adjust the spring force, the left J, resting against the end of the sleeve 5, regulate and limit the stroke of the axis. The ledge of the lever 7 rests against the cam 7. When the cam 7 is turned, the lever 7 moves, compressing the spring 6. The second end of the axis 8 has a fine tooth, which ensures the installation of the lever 9, which connects the axis 8 at a small angle with the rod of the electromagnet. The latter is connected through a rod and a hinge to a fork, from which, through a nut and a spring, the force is transmitted to the lever 9. Thus, regardless of the force of the electromagnet, the force on the lever is determined by the degree of compression of the spring.

The mechanism for switching on the transverse and vertical feeds (Fig. 130) controls the switching on and off of the cam clutches of the transverse and vertical feeds from the feed motor. Made in a separate box. When the handle 5 moves up, down, left, right, the drum 7 associated with it performs the corresponding movements and, with its bevels, through the lever system controls the switching on of the cam clutches, and through the pins - the limit switches designed to reverse the feed motor. The drum is connected by a rod 2 with a backup handle. When turning on and off the transverse stroke, the rod moves forward, and when turned on

Rice. 128. Console: a - development, b - section

Vertical stroke - turns. Screw 4 and nut 3 serve to eliminate gaps in the system.

The lead screw 1 (Fig. 131) of the table receives rotation through the sliding key of the sleeve 9, located in the bushings 5, 7. The sleeve 9 rotates from the cam clutch 6 through splines when it engages with the cams of the sleeve 5 associated with the bevel gear 4. On the sleeve 5, a ring gear is made, which is engaged with the gear wheel of the round table drive. Clutch 6 has a ring gear for rotating the longitudinal feed screw from the handwheel. The clamping of the slide on the guide console is carried out by the faceplate 8. The wheel 9 (Fig. 132) is spring-loaded in case a tooth hits a tooth. The engagement of the wheels is possible only when the clutch 6 and bushing 5 are disconnected. This blocks the handwheel during mechanical feeds. Nuts 2 and 3 of the lead screw (Fig. 131) are located on the left side of the slide. The gap in the guides of the console and slide is selected with wedges.

The longitudinal feed engagement mechanism (Fig. 132) engages the longitudinal travel cam clutch, engages and reverses the feed motor. The handle 4 is fixedly connected to the axis 2 by turning the lever 7, along the curved surface of which, when switching, the roller 75 rolls (Fig. 132). In the neutral position of the lever 10, the roller is located in the middle depression, when switched on, in one of the side depressions. The movement of the roller 15 through the lever 16 is transmitted to the rod 5 through the wheel 7 - the rail 6 and the fork 8 leading the clutch 6 (Fig. 131). Spring 2 (Fig. 132) constantly presses the rod 5. Spring 4 turns on the handle when a tooth hits the tooth of the coupling 6. Spring 4 is adjusted by screw 3 through the hole in plug 7.

On the same axis with the lever 16 there is a lever 18, which serves to turn on the clutch 6 with a cam 19 attached to the rod 20 connecting the main handle of the longitudinal stroke with the backup. Limit switch 7 7 turns on and reverses the feed motor. Its disengagement occurs after the clutch 6 is turned off. On the hub 5 (Fig. 133) of the longitudinal stroke handle there are protrusions, which are acted upon by the longitudinal stroke limitation cams or (in automatic cycles) the longitudinal stroke control cams. The operation of the limit switches is checked with the cover 14 removed (Fig. 132).

The automatic cycle mechanism is designed to control the movements of the table from the cams. Two sprockets are installed on the axis of the longitudinal stroke handle, directly connected to the sprockets 6y 5 (Fig. 133) for enabling high speed when the machine is operating in an automatic cycle. Asterisk 6 rotates from a return spring cam located on the front side of the table in a T-slot. Asterisk 3 has a different depth of depressions, which when it is turned 218

At 45 ° provides a different stroke of the rod 2 (Fig. 134), which, acting on the limit switch, turns on the high-speed electromagnet.

The clutch locking mechanism (Fig. 134) is designed to prepare the machine for work in an automatic cycle. When you press the gear shaft 2, the rack 3 disengages from the gear wheel 4 and engages with the gear shaft 2. When the shaft 2 is turned, the cam clutch moves and engages with the cam gear. From this point on, the longitudinal travel handle cannot be switched on. The clutch can only be locked in the middle (neutral) position of the handle. This is provided by a T-slot in the wheel 4 and a pin J installed in the sled body. When you press the shaft - gear 2 with cone 1 and finger 13 (Fig. 132), the contacts of the limit switch open, blocking the circuit for switching on the transverse and vertical feeds. This excludes the inclusion of two movements at the same time with the locked cam clutch of the longitudinal stroke: table and slide or table and console.

Dividing heads. Technological capabilities of milling machines expand dividing heads. They serve for periodic rotation of the workpiece around the axis (when machining teeth, splines, grooves, etc.) at equal or unequal angles, as well as for continuous rotation of the workpiece, consistent with the longitudinal feed of the machine table when cutting helical grooves. There are heads for direct division; multi-spindle; universal; optical. Dividing heads are equipped with accessories: spindle rollers; front center with leash; jack; clamps; center mandrels and cantilever mandrels for setting the workpiece; universal linings; tailstock; guitars with interchangeable gears; three-jaw chucks.

When processing using a dividing universal head, the workpiece 1 (Fig. 135, a, b) is installed on the mandrel in the centers of the spindle 6 of the head 2 and tailstock 8. The modular disk cutter 7 receives rotation, and the machine table receives a working longitudinal feed. After each periodic rotation of the gear blank, the cavity between adjacent teeth is machined. After processing the cavity, the table rapidly moves to its original position. The cycle of movements is repeated until all the teeth of the wheel are completely processed.

The working position of the workpiece is set and fixed during the rotation of the spindle 6 with the handle 3 along the dividing disk 4 with a dial. The spring device fixes the handle 3 when it hits the corresponding hole of the dividing disk. On the latter, eleven circles are concentrically located on both sides with the numbers of holes 25, 28, 30, 34, 37, 38, 39, 41, 42, 43, 44, 47, 49, 51, 53, 54, 57, 58, 59 , 62, 66.

Universal dividing heads are divided into limb (Fig. 136, a, bc) and limbless (Fig. 136, d). The rotation of the handle 7 relative to the limb 2 is transmitted through the gear wheels 5, 6 and the worm gear 7, 8 to the spindle. The heads are adjusted for direct, simple and differential division.

direct division. Provided by installing a dividing disc with 30 evenly spaced holes on the spindle. The disc is turned with a handle and the circle is divided

For 2, 3, 4, 5, 6, 15 and 30 parts. When using a special dividing disc, division into unequal parts can be performed.

A simple division (Fig. 136, a) into Z equal parts is performed when the handle is rotated relative to the fixed disk according to the following kinematic chain: 1 / Z \u003d Wp (Z5 / 2 ^) x (D / D), where (D / 2 $) x x(Zn/Zz) = /N pr - number of turns of the handle; N- characteristic of the head (usually N= 40). Then 1 / Z \u003d pr x (1 / N), from where yar - N / Z \u003d A / B, where B is the number of holes that you need to turn the handle. The sliding sector J (Fig. 135, a), consisting of two radial rulers, is moved apart by an angle corresponding to the number A of holes, and the rulers are fastened. If the left ruler rests against the handle latch, then the right one is aligned with the hole into which the latch must be inserted at the next turn.

Example. Set the dividing head for milling the teeth of a cylindrical gear with Z= 100. Characteristics of the head N- 40; Yar \u003d N / Z \u003d A / B \u003d 40/100 \u003d 4/10 \u003d 2/5 \u003d 12/30, i.e. A \u003d 12 and B \u003d 30. Thus, use the circumference of the dividing disk with the number of holes B \u003d 30, and the sliding sector is adjusted to the number of holes A = 24. 222

Differential division is used when it is impossible to select a dividing disc with the desired number of holes. If there is no required number of holes for the number Z on the disk, a number close to Z is taken, for which there is an appropriate number of holes. Difference (1/Z- compensate by additional rotation

Spindle head for this difference. It can be positive (the additional rotation of the spindle is directed in the same direction as the main one) or negative (the additional rotation is negative). This is provided by an additional rotation of the dividing disk relative to the handle, i.e. if, with a simple movement, the handle is rotated relative to the fixed disk, then during differential division, the handle is rotated relative to the slowly rotating disk in the same or opposite direction. The rotation of the disk is transmitted from the head spindle through the replaceable wheels a - bu c - d (Fig. 136, b) the conical pair 9 and 10 and the gears J and 4. The amount of additional rotation of the handle pr £ = N (/ Z - l / Ztj ) = (1/Z) x x(a/b) x (c/d) x (Z,/Z10) x (Z3/Z4).

We accept (2^/Z10)(Z3/^)= = С (usually С= 1). Then (a/b)(c/d) =N/C[(Zt> -

Example. Set the dividing head for milling the teeth of a cylindrical wheel with Z= 99. It is known that N - 40 and C = 1. The number of turns of the handle for simple division pf = 40/99. Considering that the dividing disk does not have a circle with the number of holes 99, we take Z - 100 and the number of turns of the handle Pf \u003d 40/100 = \u003d 2/5 \u003d 12/30, i.e. we take a disk with the number of holes along the circle B - 30 and turn the handle into 12 holes when dividing (A \u003d 12). The gear ratio of replaceable wheels is determined by the equation: (d / 6) x (c / rf) \u003d 7V / C \u003d [(2 ^, - Z) / 2 ^] \u003d \u003d (40/1) [ (100-99) / 100] = 40/100.

Limbless dividing heads (Fig. 136, d) do not have dividing disks. The handle is turned one turn and fixed on a fixed disk 2. With a simple division into equal parts, the kinematic chain looks like: / (a2 / b2) x (c2 / d2) x (Z3 / Z4) \u003d 1 / Z.

Considering that Z3/Z4 = /V, we get (a2/b2) x (c2/d2) = N/Z.

Optical dividing heads (Fig. 137) provide division with increased accuracy and consist of a body 7, a glass disk 2, which has 360 accurate degree divisions visible through a microscope 3. The optical system has 60 divisions for counting minutes of arc. The head is fixed in the spindle and rotated to the required angle with a reading through the eyepiece of the microscope on the scale of disk 2.

Milling of helical grooves, evenly spaced around the circumference (see Fig. 135, b), is performed when the workpiece is installed in the centers. The table is rotated by the angle of inclination of the helix of the groove so that the disk cutter 7 is aligned with the direction of the groove. The workpiece receives continuous rotation from the lead screw of the longitudinal feed, and the table receives a longitudinal feed in the direction of the groove. The kinematic chain equation from the dividing head spindle to the longitudinal feed screw (see Fig. 136, c): (Z% / Zn) (Zb / Z$) x x (Z4 / Z3) x (Zw / Z)) (d / a)(b/dx)pb = p, where pb is the lead screw pitch. Considering that (Z% / Z1) (Zb / Zs) (ZA / Zz) (ZXo / Z)) \u003d 1 / 7V (see Fig. 134, c), we get (ax / bx) (cx / dx) = N(nD/tga>)/Pb.

The bed serves for fixing all units and mechanisms of the machine. Some machine components (gear box, belt drive motor, motion transmission to feed box and machine spindle) are located inside the bed and are not visible. Other machine components (console, feed box, trunk, table, coolant pump) are located on the outer surfaces of the bed.

The bed is box-shaped and reinforced from the inside with ribs; on its front wall there are vertical guides (made in the form of a dovetail) for the console, and at the top - horizontal guides for the trunk.

The bed is the main part of the milling machine and is manufactured exactly according to the drawing and specifications. It is cast from high quality cast iron and carefully processed.

Trunk Available on horizontal and universal milling machines, it is used to correctly position and support the milling mandrel. The trunk is installed in horizontal guides on the upper part of the frame and can be fixed at any distance from its mirror, i.e. with a different reach (see Fig. 88). To increase rigidity when machining heavy parts and for large cross-sections of chips, supports are used that connect the trunk to the console.

The console is rigid iron casting mounted on vertical bed rails. The console moves along the vertical guides of the bed and carries the horizontal guides for the sled. It is supported by a post containing a telescoping screw for raising and lowering the console. The rigidity of the console structure and the accuracy of its guides are of paramount importance for the operation of the machine. There are two bolts in the console that fasten the supports that connect the machine table with the trunk for better stability under heavy loads.

The skids are an intermediate link between the console and the machine table. The table moves along the upper guides of the slide in the longitudinal direction, and the slides themselves move in the transverse direction along the upper guides of the console.

Table mounted on the guide slide and moves in the longitudinal direction. Workpieces, clamping and other devices are fixed on the table, for which the working surface of the table has longitudinal T-shaped grooves.

The movement of the table, slide and console informs the workpiece of longitudinal, transverse and vertical feeds in relation to the cutter. The greatest movements of the table, sled and console are shown in fig. 88.

Console milling machines usually have both manual and mechanical feed of the table, sled and console.

For installation movements during setup and for idle runs of the table, manual or mechanical feed can be used, and for working feeds, only mechanical feed.

In addition to working feeds, on most milling machines, the table has a fast traverse (rapid movement) in all three directions. Fast travel is provided for the supply of the workpiece to the cutter, as well as for the reverse movement of the table.

The fast stroke is carried out at one constant speed, and the working feeds have several steps, which can be set using the feed box, depending on the nature of the processing, the material of the cutter and the workpiece.

Spindle. To rotate the cutting tool, a spindle is used, which receives movement from the gearbox. The accuracy of rotation of the mandrel with the milling cutter depends on the accuracy of the manufacture of the spindle, on its strength and rigidity. The spindles of milling machines are made of 40X alloy steel and subjected to heat treatment.

On fig. 103 shows a drawing of the spindle of the 6N82G machine, from which it is clear what high requirements are placed on the cleanliness and accuracy of the machining of this part. The spindle is made hollow.

The bearing journals are machined to the 1st class of accuracy with a finish of V 8, so that the rotation of the spindle is correct. The front end of the spindle and the conical seat must be machined very accurately - places for installing and fastening tools and mandrels.

Domestic milling machines have a standard front end of the spindle, similar to that shown in fig. 59.

On fig. 104 shows the spindle of a milling machine with a milling mandrel put into a conical socket, tightened with a ramrod (tightening screw). A cutter is put on the mandrel. The mandrel, in addition to the support in the spindle seat, has support in the earring (bracket) of the trunk. As described above (see page 70), the cutter can also be mounted cantilevered on short end mandrels, or directly on the front end of the spindle, depending on its type.

The spindle is driven by an electric motor located in the machine frame. Rotation is transmitted to the machine spindle through a pulley and a belt drive. The engine is located inside the bed, which increases the safety of work and reduces the area occupied by the machine.

The table feed drive is carried out from an electric motor located in the machine console through the feed box.

Console milling machines of modern design, like the 6N82G machine, they have separate electric motors for the gearbox drive and for the feed box drive.

The gearbox is designed for transmission of rotation from the pulley to the spindle and to change the number of its revolutions by switching gears.

The feed box serves to change the amount of table feeds in the vertical, longitudinal and transverse directions.

On fig. 105 shows a horizontal milling machine model 6N81G produced by the Dmitrovsky plant of milling machines. The machine is shown disassembled so that all the main components and mechanisms can be seen.

Vertical milling machines.

The vertical milling machine is different from horizontal only by the location of the spindle, and everything stated above about a horizontal milling machine is quite applicable to a vertical milling machine, with the exception of those parts and assemblies that the latter does not have (trunk, earring).

On fig. 106 shows the main components of the 6H12 vertical milling machine manufactured by the Gorky Plant of Milling Machines.

Machines of this model, together with a horizontal milling machine 6N82G (see Fig. 85) or a universal milling machine 6N82 (see Fig. 86) form a range of cantilever milling machines of the 2nd size (see Fig. 89).

All machines of the 2nd size have 18 spindle speeds in the range of 30-1500 rpm and 18 feed steps ranging from 23.5 to 1180 mm/min for longitudinal and transverse table movements and from 8 to 390 mm/min for vertical .

The working surface of the table for machines of the 2nd size is 1500X320 mm. The table has the following maximum movements in mm:

On fig. 107 shows the main components of the 6H11 vertical milling machine manufactured by the Dmitrov Milling Machine Plant. Machines of this model, together with horizontal milling

6N81G machines (see Fig. 105) and similar 6N81 universal milling machines form a range of modern console milling machines of the 1st size.

All size 1 machines have 16 spindle speeds ranging from 65 to 1800 rpm and 16 table feed rates ranging from 35 to 980 mm/min for longitudinal movement, from 25 to 765 mm/min for transverse and from 12 to 380 mm!min For vertical.

The working surface of the table for machines of the 1st size is 1000X250 mm. The table has the following maximum movements in mm:

Consider a typical milling machine device:

Depending on the location of the machine nodes (layout), console and non-cantilever milling machines are distinguished. The main design difference in the device of a cantilever milling machine (Fig. 1) is the presence of a console moving in a vertical direction along the frame guides. Horizontal guides are made on the console, along which the sled moves, carrying the table, on which the workpiece is fixed.

Cantilever horizontal universal machines are distinguished by the fact that an intermediate rotary plate 5 is installed on the slide, along the horizontal guides of which the table moves. The spindle of the machine is located horizontally, and the trunk is mounted on the bed, carrying a supporting earring. The cutter or a set of cutters is fixed in a mandrel, one end of which is installed in the spindle, and the other in the hole of the earring.

The wide-purpose horizontal milling machine is distinguished by the presence of an additional spindle headmounted on a retractable trunk. The head can be rotated to any angle in the vertical plane. Even greater versatility is given to the machine by the presence of an overhead milling head, with a spindle that rotates at any angle in the horizontal plane. These machines do not have a turntable.

The vertical console milling machine has a vertically located spindle head, which can be rotated in a vertical plane. Known designs of machines of this type, in which there is an axial movement of the spindle.

Consoleless vertically and horizontally milling machines (Fig. 2) are distinguished by the fact that the sled carrying the table moves along the horizontal guides of the frame 1, and the spindle head moves in the vertical direction along the rack guides.

In horizontal milling machines, the spindle and gearbox shafts are often mounted directly in the rack. Changing the spindle speed is provided by a number of series-connected group gears with movable gear blocks.

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