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Milling machines 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 general purpose milling machines 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 an earring J is installed that supports the mandrel with a cutter, the console 4 moves along the rack guide 5. Slides 6 and table 7 are located on the console.

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 a rotary spindle head 2 mounted on a 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; feed limits of longitudinal and transverse 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 disks. The lever 7 is pinned on the axis 4. The latter is pressed in the direction of the frame 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. It is turned off 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 limiting 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 turning on the 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 rotated, 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 during 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 spindle of the head through the interchangeable wheels a - bu c - d (Fig. 136, b) the conical pair 9 and 10 and the gears J and 4. ) = (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 modern market for CNC milling machines offers equipment various types, but, with all the wide range of configurations, the main components of all units are the same. The exception is the support mechanisms and the movable slider (trunk), which are in horizontal type machines and are absent in vertical milling machines.

Key elements of CNC milling equipment

The device and the main components of the milling equipment of the console type

Base(reference plane) - a fixed one-piece cast structure made of gray cast iron (mainly SCH 21-40 and SCH 15-32). Designed to fix the bed, which is bolted to the top of the base. In the sub-frame space, a container for collecting coolant and electric pumps can be placed.

bed- the most important element of equipment that ties together all the nodes and mechanisms of the machine and takes on the entire load. It is a welded or cast fixed structure, reinforced with stiffeners. Inside is a gearbox, combined with a switch box, and a block with electrical equipment. Gray cast iron is used for casting, steel 3 and 4 are used for welding. Steel beds are inferior in rigidity and reliability to cast iron, but they are lighter in weight.

Welded machine base and frame with stiffeners

Guides- designed for linear movement of processing tools and workpieces along the axes of the equipment. They are made of high alloy steel and are attached directly to the frame. The accuracy of processing products depends on the quality of their execution and fixation.

Linear guides for milling machines

Sled- a machine part involved in moving the desktop and console (in console equipment).

Console- a node present in the milling machining centers of the cantilever type. It is cast from cast iron and moves parallel to the frame along vertical guides. On the side surface of the console there is a feed box, and a sled is placed on the upper part, along which the work table moves with the workpiece fixed on it.

Table- a working surface with clamping equipment for fixing workpieces, which moves along the sled. It can move in the longitudinal/transverse/vertical directions and feeds the part to the cutting tool. Since milling requires high precision, one of the main requirements for the table is the rigidity of the surface. The plane of the table should not vibrate during the operation of the cutter, bend under the weight of the workpiece, or allow other plastic deformation.

Working table with protective aluminum coating for CNC milling machining center

electrical equipment- this category includes machine elements that are responsible for the mobility of mechanical parts and the operation of auxiliary elements:

1. feed / main / auxiliary movement drives;
2. equipment failure alarm system;
3. lighting of the working area;
4. other auxiliary electrical controls.

Spindle- refers to the most important components of the machine and is designed to fasten the milling tool and give it a rotational movement. It is a heat-treated, balanced alloy steel shaft equipped with a cutter holder. The quality of the spindle determines how accurately the workpiece will be processed.

Spindle for vertical type milling machine

crawler(trunk) - an element that ensures the correct installation and support of the mandrel with a milling tool during the processing of the workpiece. It is mounted on a horizontal slide at the top of the bed.

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:

Familiarize yourself with the description of "Laboratory 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).

This equipment is for processing shaped and flat metal blanks with screw and straight generatrices. With the help of machines, you can make grooves, grooves, holes, apply internal and external threads, as well as produce a number of other technological operations. Depending on the direction of movement of the working body, horizontal and milling machines are distinguished. The main components and mechanisms in the equipment of both types are the same, except for the support and the trunk, which are not in the vertical modifications.

Base

The base is made of solid gray cast iron. When installing the equipment, the part fits snugly to the floor on one side, and the bed is fixed to the other with bolts. The base also has a special trough in which the coolant is collected, and an electric pump for supplying the coolant to the tool.

bed

All the main components and mechanisms of the milling machine are attached to the part. The spindle, gearbox, engines are hidden inside the structure, and the rest of the units are mounted on external surfaces. In the upper part of the frame, horizontal guides for moving the trunk can be located, on the front wall - vertical guides for the console or headstock. From the inside, the part is reinforced with stiffeners. The bed can be cast or welded. The first option is considered more reliable and enduring, but more complex structures are obtained by welding.

Trunk (creeper)

This node is available on horizontal and universal milling machines and is rarely found on CNC machines. The main purpose of the trunk is the correct installation and reliable support of the mandrel. The mechanism is mounted on horizontal rails of the frame and allows for a change in overhang, that is, the distance to the mirrors. When processing massive parts, when large chips are obtained, special supports are used for additional fixation of the workpiece, which form a connection between the trunk and the console.

Console

The part is cast from cast iron and mounted on vertical guides of the bed. When moving, the console, in turn, carries horizontal rails for the sled. To support the assembly, a stand is provided with a telescopic screw that allows height adjustment. The operation of the equipment largely depends on the rigidity of the console, the accuracy of the execution of its guides. Supports are attached to the element using two bolts, which ensure the stability of the entire system during operation. For consoleless machines, the vertical movement is organized by the headstock along vertical guides

Sled

Purpose of the mechanism- ensuring the relationship between the X and Y axes. The upper slide rails are used to move the table in the longitudinal direction, and the lower ones are used to move the slide along the console rails.

Table

The main working element of the milling machine, which moves on a sled. On the surface of the table there are clamping and other fixing devices for strong fastening of workpieces. For this, the part has longitudinal grooves. Collaboration table, console and slide ensures the supply of the workpiece to the cutter. Movement in the longitudinal, vertical and transverse direction is possible. Typical equipment usually has manual and mechanical feed. The use of one or another method depends on the tasks:

• for idle runs and installation movements of the table, a manual, mechanical method is used
• for working feed, most often mechanized feed is used.

Additionally, it is possible to move the table quickly, the so-called rapid move in all three directions. The movement is carried out at a constant speed (most of the machines are equipped with an additional clutch or high-speed motor), while the working feeds have a multi-stage switch box. The operator independently selects the mode depending on the material of the workpiece and cutter, as well as on the type of processing.

Spindle

One of the main mechanisms of typical equipment, the purpose of which is to transmit torque from the gearbox to the cutting tool. The part is made rigid, durable, with high dimensional accuracy, since the correctness and quality of the work of the mandrel with the milling cutter depends on its parameters. The spindle is made of alloy steel, undergoes thermal hardening, grinding, balancing.

Electric motors

The main movement - rotates the spindle, is located in the headstock or column.

Working feeds, rapid movements - fixed on the feed box

Console movement - mounted on the console, if available

Coolant supply. Located in a pallet or chip box. Other ancillary equipment - located at locations selected by the manufacturer.

Gearbox

Through the rotation of the gears and their switching, the force from the electric motor is transmitted to the spindle. The mechanism also allows you to adjust the number of revolutions of the cutting tool.

Gearbox

The purpose of the node is to change the speed of table feeds in all three directions.

Conclusion

In general, we can say that typical milling machines different kind and appointments consist of three main parts:

• motor (electric motor, gearbox and spindle);
• transmission (a set of devices that transmit rotation from engines to executive bodies);
• executive (table, caliper, spindle, cutting tool).

Control systems are also present in almost all models of modern standard equipment. There are many options for CNC, each of them has its own advantages and disadvantages.

Classification and main brands of milling machines.

Milling machines and work performed on them.

Console milling machines (CFS). Designed for processing flat and shaped surfaces of small and medium-sized parts of arbitrary shape: flat, body, such as bodies of revolution and curly. In addition to milling, the machines can be used for drilling, countersinking, boring and reaming holes, as well as threading.

The main field of use of FSC is single and small-scale production. At the same time, when equipped with special devices and devices for automating work cycles, as well as CNC systems, the machines can be effectively operated in mass production.

The dimensions of the working surface of the table are taken as the main parameter, according to which the standard-size series of machines are built.

For machining parts from several sides, the machines can be equipped with rotary tables with a horizontal or vertical axis of rotation.

The CFS carrier system consists of a base and a rack. The posts are cast from Sergo or modified cast iron and are provided with guides for vertical movement of the console and horizontal movement of the slider, if any. Guides are used both as a dovetail type and rectangular. The base planes are used as sumps and coolant reservoirs.

Tables usually have an elongated rectangular shape, with a length to width ratio of 2.5: 1, which makes it possible to work with additional devices, such as a dividing head. For fixing parts and fixtures on tables, longitudinally located T-slots are used. To move tables, screw, less often worm-and-rack gears are used.

Spindle assemblies that are fixed or located in a quill or sliding slide are subject to significant loads and are mounted on radial or angular contact roller bearings. When using radial bearings, an additional thrust ball bearing is provided.

The installation of the tool is carried out using a cone with a taper of 7:24. To transmit torque on the front end of the spindle there are removable or integral feather keys. To clamp the tool, manual or mechanized devices are used.

With manual clamping, a through hole is provided in the spindle for the rod resting against its rear end and the front threaded end interacting with the threaded hole in the tool shank.

In manual machines, step-controlled drives are usually used, which consist of an asynchronous electric motor and a gearbox. The gearbox is connected to the vertical spindle through high-speed bevel gears. Switching the spindle speed is done manually, or using hydraulic or electromechanical devices.

In automated machines with stepless control of spindle speeds, DC or AC induction motors with frequency control are used, and two or three-stage gear enumeration is used to provide constant power over most of the range.

In feed drives of manual machines, unregulated AC motors with stepped feed boxes are used.

In machines equipped with CNC devices, separate feed drives are used along controlled coordinates with adjustable electric motors connected through a gearbox or directly to ball screw mechanisms for moving the executive bodies.

Consoleless milling machines. Designed for processing flat and shaped surfaces of planar and body parts of medium and large sizes in the conditions of the main production of machine-building enterprises. Given the complexity of reinstalling large body parts on the BFS, boring and drilling operations can be carried out. The machines are equipped with swivel or swivel tables, as well as swivel and swivel tool heads.

Most modern BFS machines are equipped with CNC systems.

The carrier system of the machine tools consists of rigid (usually high-quality cast iron) parts and, in combination with a developed spindle group and a high-power main drive, provide the ability to work at optimal cutting conditions with any tools, incl. from superhard materials and ceramics.

In the guides of the movable units, sliding friction pairs along the main bearing faces and rolling along the lateral orienting sides are used.

Spindle assemblies are mounted on powerful double-row roller bearings with a tapered inner ring for tension control, and independent thrust ball bearings. It is also possible to use tapered angular contact bearings, incl. with adjustable tension. The clamping of the tool in the spindle is mechanized, and in CNC machines it is automated using spring-hydraulic devices.

The drive of the main movement is carried out from an asynchronous electric motor through a gearbox (usually 12-18 steps), or from an adjustable electric motor through a two- or three-stage enumeration.

In feed drives, adjustable electric motors are used in combination with ball screws.

The installation of machines of this type requires the pouring of a special foundation ͵ with metal supports built into it.

Classification.

Milling machines in the accepted classification make up the sixth group, in connection with this, the designation of milling machines begins with the number 6. The designation of gear-cutting machines, incl. hobbing starts with the number 5.

Vertical milling console machines. Designed to perform a wide range of milling operations performed by face, end and other cutters, which are mounted in collet chucks, leaving free cylindrical and end surface cutters.

Horizontal milling console machines. They are distinguished by the presence of a console and the horizontal position of the spindle when processing cylindrical, angular and shaped milling cutters of flat and shaped surfaces of workpieces from various materials. It is possible to use face and end mills.

Wide-purpose milling machines. They can work with a horizontal, inclined or vertical arrangement of one or two spindles when processing medium-sized parts of various shapes with all types of cutters. Are used in the conditions of single production.

Continuous milling machines. There are carousel-milling, in which the table with workpieces (carousel) rotates about the vertical axis, and drum-milling with a horizontal axis of rotation of the drum (vertical table). Are applied in the conditions of serial and mass production.

Copy-milling machines. Performed universal and specialized. The latter are used for processing specific parts (tire molds, spars, turbine blades, etc.). The executive body with a cutter repeats the movement of the copier, ĸᴏᴛᴏᴩᴏᴇ is connected with the driver.

Longitudinal milling machines. Single-column and double-column, with one or more spindles, allow you to mill vertical horizontal, inclined, grooves, etc. on long and large workpieces (weighing up to 30 tons) or simultaneously process groups of workpieces in mass production.

Vertical milling consoleless machines. They have a table on a fixed frame and move in the longitudinal and transverse directions.

Base, on which the bed is fixed, in addition, serves as a reservoir for coolant. A coolant pump is also mounted on it.

bed serves to fasten all the mechanisms of the machine. The bed is made in the form of a box-shaped part reinforced inside with stiffeners. On its front surface there are vertical guides for the console, and at the top there are vertical guides for the trunk, if it is provided.

Trunk available on horizontal and universal milling machines and is used for correct installation and support of the milling mandrel (earrings).

Console is a rigid iron casting mounted on vertical bed rails. The console has horizontal slide rails. Supported by a stand that has a telescoping screw to raise and lower the console.

Sled are an intermediate link between the console and the machine table. The slide moves in the transverse direction along the guides on the console.

Table mounted on guide rails and moves in the longitudinal direction.

The main components and mechanisms of milling machines. - concept and types. Classification and features of the category "The main components and mechanisms of milling machines." 2017, 2018.