JPH07106482B2 - Tool feeder for machine tools - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a tool feeding device for a machine tool, and particularly to an emergency stop of the machine tool when the feed of a cutting tool to a work is overloaded. Regarding the tool feeding device.

[Conventional technology]

A machine tool for cutting a shaft, for example, a crankpin of a crankshaft, is disclosed in Japanese Patent Publication No. 56-45726 and Japanese Patent Laid-Open No. 53-8.
Various types are known as can be seen in Japanese Patent Publication No.

Of these, machine tools such as pin turning lathes are fixedly held at both ends of the shaft with tailstocks, and the tool head is rotated around the periphery of the shaft and fed to the tool rest to cut the shaft to a specified diameter. To do.

In such a work-fixing and tool turning type machine tool for shaft machining, a tool head with a built-in tool feed mechanism is swiveled around the shaft at high speed to improve the machining efficiency of the shaft, for example, the crankpin of the crankshaft. If you try
It is desired to simplify and reduce the weight of the blade feeding mechanism incorporated in the turning tool head.

Therefore, the applicant of the present application has already applied for a work fixed tool turning type machine tool satisfying the above-mentioned demand in Japanese Patent Application No. 61-42724. This is because a spindle drive gear and a feed gear with a smaller number of teeth are coaxially combined, and both gears are rotated through the same gear train to cause a rotation phase shift between the gears and By utilizing the phase shift motion, the feed groove installed in the main shaft drive gear is in-fed by the cam groove formed in the feed gear and the cam follower engaged with the cam groove.

[Problems to be solved by the invention]

In the tool feeding device as described above, when the cutting blade is rubbed or broken, the cutting speed is reduced, the cutting resistance is greatly increased, and the cutting feed is overloaded. Therefore, the workpiece may be deformed in the radial direction or may be damaged, and the tool feed table or the like may be destroyed.

[Object of the Invention]

The present invention has been made to solve the above problems, and secures the safety of the machine tool even if the cutting feed becomes overloaded due to friction, breakage, etc. on the cutting blade, and the work piece and the feed table. It is an object of the present invention to provide a tool feeding device for a machine tool that prevents deformation and destruction of the machine.

[Means for solving problems]

A tool feeding device for a machine tool according to the present invention includes a hollow spindle rotatably provided in a machining unit main body, a spindle driving gear concentrically and integrally attached to the hollow spindle, and the spindle driving gear facing the spindle driving gear. A feed gear that is attached to a hollow main shaft so as to be relatively rotatable and has a different number of teeth from the main shaft drive gear, a motor that rotationally drives the main shaft drive gear and the feed gear, and the rotation of the motor is the main shaft drive gear and the feed gear. And a cutting blade that is transmitted to each of the shafts and has the same number of intermediate teeth on the same axis, and is movably installed in the main shaft drive gear in the radial direction thereof, and that is projected toward the outer periphery of the workpiece shaft. And a tool feed table having, wherein the feed gear has a ring-shaped cam groove for infeed with which a cam follower attached to the tool feed table is press-engaged, and the main shaft drive gear and Cutting resistance becomes larger than the feed force due to the rotational phase shift between the helical gears, and the rotational phase shift between the two gears disappears. Instead, an overload detection mechanism that operates by the rotational shift generated between the intermediate gears is provided. It is a thing.

[Operation of the invention]

In the present invention, when the main shaft drive gear and the feed gear rotate, a rotational phase shift occurs between the gears, whereby the cam follower traces the cam groove, and the tool feed base is fed in. If the cutting feed becomes overloaded due to cutting friction, breakage, etc., there will be no rotational phase shift between the spindle drive gear and the feed gear, and this will cause a rotational shift between the intermediate gears that mesh with the spindle drive gear and the feed gear. The overload detection mechanism detects the rotational deviation and issues an emergency stop command to stop the machine tool in an emergency. Therefore, breakage and deformation of the cutting blade, the feed mechanism, the workpiece, etc. due to the overload of the cutting feed can be prevented in advance.

Example of Invention

 Embodiments of the present invention will be described below with reference to the drawings.

1, 2, and 3 are plan views of a crankpin cutting machine tool equipped with a tool feeding device according to the present invention, respectively.
FIG. 3 is a sectional view taken along the line III-III in FIG. 1 on the front side, and FIGS. 4 to 6 show the details of the one cycle end detection mechanism and the overload detection mechanism of the tool feeding mechanism according to the present invention. is there.

In FIG. 1 to FIG. 3, 1 is a bed, and the upper surface of the bed is four parallel first, second and
The third and fourth guide surfaces 2a, 2b, 2c, 2d are formed along the longitudinal direction of the bed 1. 3 is located on one longitudinal end of the bed 1 and extends over the first guide surface 2a and the third guide surface 2c located behind the second guide surface 2b adjacent to the first guide surface 2a. First tailstock installed so that it can be moved in the longitudinal direction, 4
Is located at the other end of the bed 1 in the longitudinal direction and is movably installed in the longitudinal direction of the bed 1 across the second guide surface 2b and the fourth guide surface 2d on the rear side of the third guide surface 2c. Is a second tailstock, and each of these tailstocks 3 and 4 is a chuck for gripping a journal 5a at both ends of a shaft to be processed, for example, a crankshaft 5.
6 and 7 are arranged on the same axis, respectively, and inside the tailstocks 3 and 4, hydraulic cylinders for operating the chucks 6 and 7 and crankpins of the crankshaft 5 are provided.
An indexing mechanism for indexing 5b to the processing position (not shown because all are known techniques) is mounted.
Further, 8 is located between the tailstocks 3 and 4 close to the first tailstock 3 and extends over the second and fourth guide surfaces 2b and 2d of the bed 1 in the longitudinal direction of the bed 1. Is a movable saddle, 9 is an NC servomotor attached to the bed 1 corresponding to the saddle 8, and a ball screw 10 rotated by this servomotor 9 is screwed into a ball nut 11 provided on the saddle 8. By driving the servomotor 9, the saddle 8 can be moved in the axial direction of the crankshaft 5.
Reference numeral 12 is a processing unit installed on the saddle 8 so as to be movable in a direction orthogonal to the moving direction.
Is moved in a direction orthogonal to the saddle 8 by a hydraulic cylinder 13 or the like installed in the saddle 8.

As shown in FIGS. 4 and 5, the processing unit 12 includes a hollow main shaft 15 which penetrates the unit main body 14 in the same direction as the moving direction of the saddle 8, and the hollow main shaft 15
Is rotatably supported in the unit main body 14 by ball bearings 16a and 16b, and a donut plate-shaped main shaft drive gear 17 is concentrically and integrally fixed to the front end by a bolt 18 and further rear end A bearing retainer 19 is integrally fixed to the bolt with a bolt 20. Further, a ring-shaped feed gear 22 is provided on the outer periphery of the collar 21 fitted to the outer periphery of the front end of the hollow main shaft 15.
Is rotatably fitted with respect to the hollow main shaft 15, and the feed gear 22 has the same diameter as the main shaft drive gear 17, and has one tooth and an optimum number of teeth smaller than that. Reference numeral 23 is a drive shaft rotatably supported by the unit main body 14, a pinion gear 24 is fixed to one end thereof, and the other end is coupled to a rotary shaft 25a of a servomotor 25 fixed to the rear surface of the unit main body 14 by coupling 2
Connected by 5b. Reference numeral 26 denotes a hollow intermediate shaft which is located between the drive shaft 23 and the hollow main shaft 15 and is rotatably supported by the unit main body 14, and one end of which is the pinion gear 24.
And a first intermediate gear 27 meshing with the main shaft drive gear 17 is fixed, and a second intermediate gear 28 meshing with the feed gear 22 with the same number of gears as the first intermediate gear 27 is coupled by a slide pin 29. ing. The slide pin 29 penetrates the intermediate shaft 26 slidably in the diametrical direction, and one end of the slide pin 29 engages with a recess 28a formed in the inner circumference of the second intermediate gear 28 as shown in FIG. The second intermediate gear 28 is connected to the intermediate shaft 26. Further, the slide pin 29 has an inclined surface 29a, and the pressing pin 30 engaging with the inclined surface 29a is the intermediate shaft 2
It is slidably inserted in 6 along its longitudinal direction. One end of an operating rod 31 inserted into the intermediate shaft 26 is coupled to the pressing pin 30, and the other end thereof penetrates a load adjusting screw 32 screwed into the other end opening of the intermediate shaft 26 to form the intermediate shaft.
26, a compression spring 34 is interposed between a load adjusting screw 32 and a nut 33 that is located outside the intermediate shaft 26 and screwed into the operating rod 31.
By applying a pressing force to the slide pin 29 side, the tip of the slide pin 29 is pressed into engagement with the recess 28a of the intermediate gear 28. Then, when the feed gear 22 becomes overloaded and there is no phase difference between the feed gear 22 and the main shaft drive gear 17, the second intermediate gear 28 is rotated with respect to the intermediate shaft 26, and the slide pin 22 is rotated. 29 is pushed inward, its movement is transmitted to the operating rod 31, and the switch 35 installed so as to face the outward protruding end of the operating rod 31 is operated. That is, the intermediate gear 28, the slide pin 29, the pressing pin 30, the operation rod 31, the spring 34, and the switch 35 constitute an overload detection mechanism when the feed is overloaded, and the switch 35 operates. When this is done, an emergency stop command is issued to the machine tool.

On the other hand, a tool feed base 36 having a hole 36a for inserting a crankshaft in the center is formed on the front wall of the main shaft drive gear 17 as shown in FIGS. It is slidably supported in the diameter direction of the main shaft drive gear 17 by a pair of freely fixed parallel retainers 37a, 37b, and the outer shape of a shaft such as a crank pin is cut on the inner wall of the central hole 36a. A cutting blade 38 that protrudes inward is provided, and a bracket 40 that supports a roller shaft 39 is arranged at a right angle on one end side of the tool feed base 36. The bracket 40 includes a taper ring 41 and a bolt. It is integrally fixed to the tool feed base 36 by 42. The protrusion of the bracket 40 toward the main shaft drive gear 17 is inserted into a hole 17a formed in the main shaft drive gear 17 that is sufficiently larger than the outer diameter of the bracket 40, and the feed gear of the roller shaft 39. The main shaft drive gear 17 of the feed gear 22 is
A roller type cam follower 44 that engages with an annular cam groove 43 is attached to the side contact surface.

As shown in the development view of FIG. 7 (a), the cam groove 43 imparts a motion in the infeed direction to the cutting blade 38. Therefore, the rapid advance lead portion 43a, the cutting feed lead portion 43b, and the dwell lead are used. Part 43c, rewind lead part 43d and zero feed part 4
3e and a cam surface, which has n (integer) pieces as one cycle, and is formed equally in one revolution of the cam groove 43. Further, in order to press the cam follower 44 against each lead portion of the cam groove 43 to remove the backlash, a compression spring 45 is mounted inside the other end portion of the tool feed base 36 opposite to the installation position of the cam follower 44, Both ends of the compression spring 45 are locked by studs 46 fixed to the tool feed base 36 and the spindle drive gear 17, respectively.

Next, a one-cycle detecting mechanism for crank pin machining will be described by directly utilizing the movement of the tool feed base 36.

As shown in FIGS. 4 and 5, the 1-cycle end inspection mechanism is provided with four rods 47 arranged at intervals of 90 ° in the circumferential direction of the hollow main shaft 15, and each of the rods 47 is provided with the hollow main shaft 15. The compression springs 48, which are slidably fitted in the four holes 48 bored to the desired depth in the longitudinal direction from the front end face (spindle drive gear 17) side, are inserted into the holes 48 respectively. Is urged in a direction in which it is pressed against the back surface of the tool feed base 36, and a protruding tip is pressed against each rod 47, and an inclined groove 50 is formed on the back surface of the tool feed base 36.
By pressingly engaging the tip of 47, the movement of the tool feed base 36 is converted into the movement of the rod 47 in the axial direction of the hollow main shaft 15. Further, on the outer circumference of the hollow main shaft 15, there is a ring 51 that is loosely fitted so as to be slidable in the axial direction thereof,
This ring 51 is fixed to each rod 47 by a set screw 52 through an elongated hole 15a formed in the hollow main shaft 15. 53
Is a proximity switch that operates by sensing the position of the ring 51. The switch 53 is arranged on the outer peripheral portion of the hollow main shaft 15 and attached to the support member 54. Further, 55 is a position sensor for stopping the fixed position of the hollow main shaft 15 attached to the support member 54, and a fixed position stop member 56 for operating the position sensor 55 is provided on the outer peripheral surface of the hollow main shaft 15 facing the position sensor 55.
Is stuck.

Next, the operation of this embodiment configured as described above will be described.

The crank pin 5b of the crank shaft 5 is fixed to the work piece, and when machining is performed by turning the tool, first, the tailstocks 3 and 4 are set to the first and third guide surfaces 2a and 2c depending on the length of the crank shaft 5. 2nd, 4th
It is moved on the guide surfaces 2b, 2d and fixed at a position adapted to the length of the crankshaft 5. After that, both end journal portions 5a of the crankshaft 5 are gripped by the chucks 6 and 7 of the tailstocks 3 and 4, respectively. At this time, the indexing mechanism of the chucks 6 and 7 operates to determine the phase in the rotation direction of the crankshaft 5,
The 1P and # 3P crankpins 5b are placed horizontally with respect to the core of the journal portion 5a.

Then, by driving the servo motor 9 to rotate the ball screw 10, the saddle 8 is moved in the direction of arrow A in FIG. 1, and the cutting blade 38 is moved to, for example, the # 4P crank pin 5b.
Position so as to face. # 4P crank pin 5b
When the position of the cutting blade 38 is completely indexed, the hydraulic cylinder 13 is operated to move the machining unit 12 to a position where the axis of the hollow spindle 15 coincides with the center of the crankpin 5b of # 1P, # 4P. , Move the machine tool to the crank pin cutting mode.

Servo motor for cutting by setting the cutting mode of the machine tool
When 25 is activated, its rotation is driven shaft 23, pinion gear 2
It is transmitted to the spindle drive gear 17 and the feed gear 22 via the 4 and the intermediate gears 27 and 28. Along with this, the main shaft drive gear 17 is rotated integrally with the hollow main shaft 15, and the feed gear 22 is provided with a collar 21.
Will rotate around.

Here, if the number of teeth of the spindle drive gear 17 is M, the feed gear
The number of teeth for 22 is M-1. Therefore, the main shaft drive gear 17 is N
When rotated, the feed gear 22 makes N + 1 rotations. That is, a phase shift corresponding to one rotation occurs between the main shaft drive gear 17 and the feed gear 22, and the tool feed base 36 is infed by the shift rotation and the cam groove 43 between them.

That is, the cam follower 44, which is constantly in pressure contact with the compression spring 45, is fed through the cam groove 43 in FIG. When engaged with the lead portion 43a for tool,
The cutting blade 38 including the above is rapidly advanced by the lead portion 43a in the direction of approaching the crank pin 5b (# 4P). Then, when the cam follower 44 moves to the lead portion 43b, the tool feed base 36 enters a cutting feed with a small infeed amount, and the outer diameter of the crank pin 5b (# 4P) is cut by the cutting blade 38. In the next area of the lead part 43c for the dwell, the outer diameter of the crank pin 5b is finish-cut to a fixed size. Then, when the cam follower 44 comes into engagement with the quick-return lead portion 43d after passing through the dwell lead portion 43c, the tool feed base 36 including the cutting blade 38 is fast-returned to complete the cutting of the cutting blade 38. Rapidly retreat in the direction away from the crank pin 5b (# 4P).

The speed pattern of the servo motor 25 during the cutting cycle is shown in FIG. 7 (b). In FIG. 7 (b), the servomotor 25 is rotated at a constant speed v ₂ at a high speed in a region between the relative deviation angles θ ₁ to θ ₂ of the gears 17 and 22.

On the other hand, when the tool feed base 36 is cut and fed, and the tool feed base 36 moves in the direction of arrow B in FIG. 5, the rods 47 press-engaged with the inclined groove 50 move in the direction of arrow C in FIG. The ring 51 also moves in the same direction at the same time. Then, when the tool feed base 36 starts shifting to the rapid return after the constant-dimension cutting of the crank pin 5b is completed, the ring is interlocked with the movement.
51 starts to move in the direction opposite to arrow C. When this is detected by the proximity switch 53, a signal is sent from the proximity switch 53, and this signal is applied to the control circuit (not shown) of the servo motor 25 to suddenly brake the servo motor 25 and rotate the servo motor 25. The speed is set to a predetermined low speed v ₁ as shown in FIG. 7 (b). Then, the quick return operation of the tool feed base 36 is performed, and the relative deviation rotational speed of both gears 17, 22 becomes 360.
When the angle θ ₃ is reached, the position sensor 55 senses the fixed position stop member 56 and applies the signal to the control circuit of the servo motor 25. Sudden braking of servo motor 25 and hollow spindle
Stop 15 in place.

The stop position at this time is a position having a rotational phase difference of 180 ° with the counterweight of the crankshaft 5, and has a positional relationship between the cutting blade 38 and the crank pin 5b (# 4P) as shown in FIG. . This is done because the cutting blade 38 and the crankshaft 5 interfere with each other when the machining unit 12 is moved in the axial direction of the crankshaft 5 if the above-mentioned stop position is largely displaced.

In addition, even if the stop position of the hollow main shaft 15 is normal, the positioning of the tool unit 12 in the longitudinal direction of the crankshaft is poor, or the position of the crankshaft 5 in the rotational direction is not properly indexed. Even when the motor 25 is started, the hollow main shaft 15 is rotated once while the speed is low and the torque is limited, and it is confirmed whether or not the cutting blade 38 and the crankshaft 5 have a normal positional relationship. The control in this case is performed by a timer (not shown) and corresponds to the range of θ ₀ to θ _{1 in} FIG. 7 (b).

If the hollow spindle 15 rotates once, the crankshaft 5 and the cutting blade 38
If and interfere with each other, the rotation of the hollow main shaft 15 will stop at the time of the interference, so the hollow main shaft 15 will not rotate once even if the time exceeds the set timer. Therefore, such an abnormality can be easily found. In addition to being able to do so, it is also possible to stop the cutting cycle of the machine tool.

On the other hand, during the cutting cycle of the crank pin 5b, the cutting blade 38 rubs and the cutting resistance increases significantly, or
If the feed force to the tool feed base 36 becomes more than the feed force due to the rotational phase shift between the spindle drive gear 17 and the feed gear 22 and becomes overloaded due to breakage of 38, the cam follower 44
Then, the cam groove 43 is locked, and the main shaft drive gear 17 and the feed gear 22 are integrated with each other, and both are rotated integrally without causing a rotational phase shift. For this reason, a rotational deviation occurs between the first intermediate gear 27 and the second intermediate gear 28 that mesh with the main shaft drive gear 17 and the feed gear 22, respectively. That is, since the second intermediate gear 28 starts to rotate with respect to the intermediate shaft 26, the slide pin 29 that is recessed in the recess 28a of the second intermediate gear 28 resists the spring 34 in the direction of arrow D in FIG. Then, the pressing pin 30 engaged with the inclined surface 29a and the operation rod 31 connected to the pressing pin 30 are slid in the direction of arrow E in FIG. 4, and the switch 35 is turned on. When the switch 35 is turned on, the ON signal is supplied to the control circuit (not shown) of the machine tool, and the machine tool is stopped in an emergency. As a result, it is possible to prevent the feed mechanism or the like from being deformed or destroyed due to overloading of the feed.

The adjustment of the overload on the feed gear 22 can be performed by adjusting the spring pressure of the spring 34 with the adjusting screw 32.

Further, the tool feeding device according to the present invention is not limited to the cutting work of the crankpin of the crankshaft as in the above-mentioned embodiment, but it is needless to say that the tool feeding device can be used for machining a cylindrical cam and other shafts.

〔The invention's effect〕

As described above, according to the present invention, the main shaft drive gear and the feed gear are rotationally driven through the different intermediate gears provided coaxially with the same number of teeth, and the rotational phase between the feed gear and the main drive gear is increased. When the cutting resistance becomes larger than the feed force due to the shift and the rotation phase shift between both gears disappears, a rotation shift is generated between the above intermediate gears, and an overload detection mechanism that operates due to this rotation shift is provided for cutting. Since the overload of the feed can be detected and the machine tool can be stopped in an emergency, it is possible to ensure the safety of the machine tool even if the cutting feed becomes overloaded due to cutting friction, breakage, etc. It is possible to prevent deformation and destruction of the.

[Brief description of drawings]

1 is a plan view of a machine tool for cutting a crankshaft provided with a tool feeding device according to the present invention, FIG. 2 is a front view thereof, FIG. 3 is a sectional view taken along line III-III of FIG. FIG. 4 is a sectional view showing an example of the tool feeding device according to the present invention, and FIG.
Fig. 6 is a side view along the line V-V in Fig. 6, Fig. 6 is a cross-sectional view along the line VI-VI in Fig. 4, Fig. 7 (a) is a development view for explaining the cam groove for blade infeed in the present invention, FIG. 7B is a speed pattern diagram of the spindle servomotor corresponding to the blade infeed cam groove. 12 …… Processing unit, 14 …… Unit body, 15 …… Hollow spindle, 17 …… Spindle drive gear, 21 …… Collar, 22 …… Feed gear, 23 …… Drive shaft, 24 …… Pinion gear, 25… … Servo motor, 26 …… Intermediate shaft, 27, 28 …… Intermediate gear, 29 ……
Slide pin, 30 …… Pressing pin, 31 …… Operating rod, 34
...... Spring, 35 ...... Switch, 36 ...... Tool feed bar, 38 ......
Cutting blade, 43 …… Infeed cam groove, 44 …… Cam follower, 47 …… One cycle detection rod, 50 …… Inclined groove,
51 …… ring, 53 …… proximity switch.

Claims (2)

[Claims] 1. A hollow spindle rotatably provided in a processing unit main body, a spindle drive gear concentrically and integrally attached to the hollow spindle, and a relative rotation relative to the hollow spindle facing the spindle drive gear. A feed gear that is attached and has a different number of teeth from the spindle drive gear, a motor that rotationally drives the spindle drive gear and the feed gear, and transmits the rotation of the motor to the spindle drive gear and the feed gear separately,
The number of intermediate teeth having the same number of teeth on the same axis, and a tool feed table having a cutting blade that is installed in the main shaft drive gear so as to be movable in the radial direction thereof and that protrudes toward the outer periphery of the workpiece shaft are provided. The feed gear is formed with a ring-shaped cam groove for infeed to which a cam follower attached to the tool feed table is press-fitted, and a feed force due to a rotational phase shift between the spindle drive gear and the feed gear is used. The tool feed of the machine tool is characterized in that the cutting resistance is increased and the rotational phase shift between the two gears is eliminated, and in place of this, an overload detection mechanism that operates by the rotational shift generated between the two intermediate gears is provided. apparatus. 2. An overload detection mechanism, a slide pin for engaging and disengaging an intermediate gear meshing with a feed gear with respect to a shaft of another intermediate gear, and a spring for urging the slide pin in a direction of engaging the intermediate gear. The tool feeding device for a machine tool according to claim 1, further comprising: a switch that is turned on / off in association with the movement of the slide pin.