JP7579960B2 - Work clamping device - Google Patents

Description

The present invention relates to a work clamping device that is compatible with a workpiece having a tapered hole formed in the center.

In a hobbing machine, the outer periphery of a workpiece having a hole formed in the center is cut, and the center of the workpiece is held by a work clamping device. The work clamping device of a workpiece for machining, deburring, polishing, etc. on the outer periphery of the workpiece is configured to hold the workpiece at the center where the hole is formed. An example of such a work clamping device is disclosed in the following Patent Document 1. In the work clamping device of the same document, a first support is provided on a base on a hobbing machine table, and a second support is attached to an upper center support via a rotary joint so as to face the first support. The first support is provided with three support claws that support the lower end surface of a workpiece having a central hole formed therein, and three centering claws that center the workpiece. The support claws are arranged at positions corresponding to the size of the workpiece, and the centering claws abut against the inner diameter surface of the workpiece to center it.

JP 2000-343329 A

Conventional work clamping devices had various problems. For example, when the center hole of a workpiece is tapered, conventional devices with a chuck mechanism that clamps with centering jaws could not handle it, and it was necessary to newly manufacture a work clamping device with a special chuck mechanism. Conventional work clamping devices are also configured to support the workpiece by centering it from below. Therefore, when the workpiece needs to be placed in the next processing machine, etc., with an autoloader that transports the workpiece, it is necessary to once send it to the inversion device, re-grab the inverted workpiece there, and send it to the next processing machine, etc. Alternatively, an auxiliary loader for inverting the workpiece was built into a processing machine such as a hobbing machine, and the workpiece was inverted there and transported to the next process by the autoloader. However, both of these configurations require new equipment, which is costly and also hinders the compactness of the processing machine.

Therefore, in order to solve this problem, the present invention aims to provide a work clamping device that enables the workpiece to be sent to the next process in an inverted state.

A work clamping device in one embodiment of the present invention comprises a lower unit in which a lower clamp block that supports the work from below is rotated by a drive motor, an upper unit in which an upper clamp block that holds down the work from above is rotatable by a rotating shaft coaxial with the lower clamp block, a lift mechanism that raises and lowers the upper unit along the rotating shaft, an actuator that moves the upper unit in the direction of the rotating shaft in the lifting section of the lift mechanism, an upper and lower unit connecting mechanism that grips a retraction rod on the rotating shaft protruding downwardly of the upper unit inside the lower unit and retracts it downward, and a tapered arbor that is assembled so that the retraction rod does not fall out when it is inserted through the arbor, and that fits into the tapered central hole of the work by the force of a biasing member.

According to the above configuration, the upper unit is lowered to the clamping position by the lift mechanism, and the actuator is operated to clamp the workpiece between the lower clamp block and the upper clamp block. At this time, the tapered arbor biased by the biasing member fits into the tapered central hole of the workpiece, thereby centering it, and the upper/lower unit connecting mechanism causes the retraction rod protruding downward from the upper unit to be retracted downward inside the lower unit, securely clamping the workpiece. The workpiece is then rotated by the drive motor of the lower unit and a specified process is performed, and when the upper unit rises to release the processed workpiece, the tapered arbor with the tapered arbor fitting into the central hole is lifted, making it possible to remove it in an inverted state.

FIG. 2 is a front view showing a processing machine line. FIG. 2 is a perspective view showing a hobbing machine module. FIG. 2 is a perspective view showing the hobbing machine module without the exterior cover. FIG. 4 is a cross-sectional view showing the work clamping device during work transfer. 1 is a cross-sectional view of a work clamping device showing one stage of a work clamping process. FIG. 1 is a cross-sectional view of a work clamping device showing one stage of a work clamping process. FIG. 1 is a cross-sectional view of a work clamping device showing one stage of a work clamping process. FIG. FIG. 4 is a cross-sectional view showing the work clamping device when the work is released.

An embodiment of the work clamping device according to the present invention will be described below with reference to the drawings. In this embodiment, a hobbing machine constituting a machining line will be described as an example. FIG. 1 is a front view showing the machining line. In the machining line 100, lathes, machining centers, inspection machines, etc. are installed side by side between a work input module 1 at the right end of the drawing, which is the work input section, and a work discharge module 11 at the left end of the drawing, which is the work discharge section. Various automatic working machines such as lathes, machining centers, inspection machines, and hobbing machines are modularized.

Next to the workpiece input module 1, lathe modules 2 and 3 and an inspection module 4 are installed in sequence, and the dimensions of the workpieces that have undergone the first and second machining processes are checked. In addition, a workpiece placement module 5 for workpiece transfer and quality check is installed, followed by a machining center module 6 for performing the third machining process such as boring and drilling. Next to this are a second workpiece placement module 7 where the workpiece can be temporarily placed and removed, and a hobbing machine module 8 for performing gear cutting as the fourth machining process. Next to this are a deburring module 9 for removing burrs from the workpiece and a cleaning module 10 for washing off chips and the like that have adhered to the workpiece.

In the processing machine line 100, the workpieces are moved in sequence among the various modules 1 to 11 while undergoing the prescribed processing and treatment. The processing machine line 100 is provided with a workpiece transport robot 15 for transporting the workpieces to each of the modules 1 to 11. The workpiece transport robot 15 is a multi-joint robot arm that moves on running rails provided at the front of each of the modules 1 to 11. The modules 1 to 11 are covered by an exterior cover 16 with a unified appearance, and as shown in Figure 2, a transport space 18 in which the workpiece transport robot 15 moves is defined by an openable front cover 17.

Figure 2 is a perspective view of the hobbing machine module 8, and Figure 3 is a perspective view of the hobbing machine module 8 excluding the exterior cover 16 and the front cover 17. The hobbing machine module 8 is assembled on a movable bed 21 equipped with wheels like the other modules, and can move in the front-rear direction along rails 121 fixed to the upper surface of the base 12. The various modules 1 to 11 have a uniform width dimension, and two modules can be mounted on one base 12, with the hobbing machine module 8 being configured with twice the width dimension. In this embodiment, the fore-and-aft direction of the machine body is described as the X-axis, the width direction of the machine body is the Y-axis, and the vertical direction is the Z-axis.

In the hobbing machine module 8, a column 23 on a movable bed 21 can move in the X-axis direction between the front and rear of the machine body, and a saddle 24 is attached to the front of the column 13 in a state where it can slide in the Z-axis direction, and is configured to be raised and lowered by a Z-axis servo motor 25. A hob head 26 that supports a hob 27 is attached to the saddle 24. The hob 27 is rotatably supported by a rotary shaft in the Y-axis direction, and is rotated by a hob motor during gear cutting. The hob head 26 is structured to be movable in the Y-axis direction relative to the saddle 24 by a Y-axis servo motor 28 so that the position of the blade of the hob 27 can be changed. A control panel 29 for controlling each drive unit of the hobbing machine module 8 is mounted on the movable bed 21.

A work clamping device 30 is provided on the front side of the hob 23. FIG. 4 is a cross-sectional view showing the work clamping device 30, and shows a part of the work transport robot 15 in a work transfer state. The work clamping device 30 is configured with a lower unit 31 and an upper unit 32 arranged coaxially with the center of rotation aligned with the Z axis. A support column 33 is erected on the movable bed 21, and a lift mechanism is configured to move the upper unit 32 up and down in the Z axis direction. That is, a vertical rail is fixed to the support column 33, and a lift 34 holding the upper unit 32 is slidably attached thereto. A Z-axis servo motor 35 is provided at the top of the support column 33, and its rotation output is converted into linear motion of the lift 34 by a ball screw.

The lower unit 31 has a table 41 fixed to the movable bed 21, within which a hollow spindle 42 is supported for rotation with its center of rotation aligned with the Z-axis, and the rotation of a spindle motor 43 (see Figure 3) is transmitted via a worm gear 44. A lower clamp block 47 is attached to the spindle 42 via connecting blocks 45, 46 so that they rotate together. The connecting blocks 45, 46 and the lower clamp block 47 have a hollow hole coaxial with the spindle 42, into which a retraction shaft 51 is assembled while being constantly biased downward by a spring 52. The spring 52 is made up of multiple disc springs stacked in the axial direction.

A piston rod 531 is inserted from below into the spindle 42. A hydraulic cylinder section 54 is formed at the bottom of the lower unit 31, and a piston 53 is incorporated integrally with the piston rod 531. A port 541 is formed in the lower pressurized chamber of the piston 53 in the cylinder section 54, and the piston 53 is configured to be displaced upward as shown by hydraulic oil supplied from there. In other words, the piston 53 is configured to push up the retraction shaft 51 against the biasing force of the spring 52.

Next, a cylindrical support portion 341 is formed on the lift 34, and the upper unit 32 is slidably inserted into the support portion 341 via a cylindrical lift pipe 61. A hydraulic cylinder 37 is fixed to the lift 34 via a bracket 36, and the lift pipe 61 is connected to the hydraulic cylinder 37 via a connecting block 62. Thus, the upper unit 32 is configured to move up and down relative to the lift 34 by the extension and contraction of the piston rod 371 in the hydraulic cylinder 37.

A shaft 65 with a flange portion 651 is inserted from below into the lift pipe 61 and the skirt block 64 fixed to its lower end. The shaft 65 is rotatably held by a bearing between the lift pipe 61 and the shaft 65, and in addition to the radial bearing, a thrust bearing is provided to support the axial load. The hydraulic cylinder 37 and the shaft 65 are configured so that their centers are coaxially aligned along the Z axis.

The upper clamp block 66 and the retraction rod 67 are fixed integrally to the flange portion 651 of the shaft 65. The cylindrical upper clamp block 66 is closed at the top by the flange portion 671 of the retraction rod 67, and a tapered arbor 71 is incorporated therein, which is inserted through the retraction rod 67 protruding downward. The retraction rod 67 has a head portion 672 formed by a circumferential recess formed at the tip, and the top member 55 provided near the opening of the retraction hole 511 of the retraction shaft 51 of the lower unit 31 is hooked onto the head portion 672.

The workpiece W to be machined has a tapered central hole H with an inclined inner circumferential surface so that the diameter at the bottom is smaller at the center. Therefore, the tapered arbor 71 has a tapered surface that matches the angle of the central hole H. The tapered arbor 71 is assembled so that it does not fall out downward by hooking the flange portion, and is biased downward by the spring 72 above. The upper clamp block 66, the retraction rod 67, and the tapered arbor 71 are assembled so that they can be disassembled by screwing or the like, and are fixed integrally to the shaft 65 by screwing. In other words, the tapered arbor 71 can be rearranged to correspond to the hole shape of the workpiece W.

Next, the operation of the work clamping device 30 will be described along with the machining of the workpiece W by the hobbing machine in the machining machine line 100. In the machining machine line 100, as described above, the first machining and the second machining are performed in the lathe modules 2 and 3, and the dimension confirmation is performed in the inspection module 4. A quality check is performed in the workpiece placement module 5, and the third machining is performed in the machining center module 6. In these processes, the workpieces are transported in order by the workpiece transport robot 15 on the right side of FIG. 1 and temporarily placed on the workpiece placement module 7. In the subsequent process, the workpiece is removed from the workpiece placement module 7 and the gear cutting is performed in the hobbing machine module 8, and the burr is removed by the deburring module 9 and the chips and the like are washed off by the cleaning module 10.

As shown in Fig. 4, the workpiece W is carried into the hobbing machine module 8 by the workpiece transport robot 15. At the tip of the workpiece transport robot 15, there is a robot hand (omitted from the drawing) equipped with a pair of chucks, and the machined workpiece Wa is removed by one chuck, and a new workpiece W gripped by the other inverted chuck is placed on the vacant lower clamp block 47. Figs. 5 to 7 are diagrams showing the workpiece clamping process of the workpiece clamping device 30 in a step-by-step manner, which grips the workpiece W so that it can be machined.

First, as shown in Figure 5, the upper unit 32 held by the lift 34 is lowered by the drive of the Z-axis servo motor 35. At this time, the upper clamp block 66 is positioned at a fixed distance above the workpiece W, and the retraction rod 67 protruding downward penetrates the workpiece W and is inserted into the retraction hole 511 formed in the retraction shaft 51. Then, as shown in Figure 6, the hydraulic cylinder 37 is extended while keeping the height of the upper unit 32 constant. This causes the lift pipe 61 and the shaft 65 rotated and held therein to lower.

As the shaft 65 descends, the upper clamp block 66 comes into contact with the workpiece W, and the workpiece W is sandwiched between the upper clamp block 66 and the lower clamp block 47 from above and below. At this time, the tapered arbor 71 is pushed into the center hole H of the workpiece W by the spring 72, and centering is performed. Then, as shown in FIG. 7, the retraction rod 67 is inserted further deeply into the retraction hole 511 of the retraction shaft 51. That is, in the lower unit 31 up to this point, the piston 53 is pressurized from below by the hydraulic oil supplied from the port 541 into the cylinder portion 54, pushing up the retraction shaft 51.

Then, the hydraulic oil in the cylinder portion 54 is discharged from the port 541, and the piston 53 is released from the hydraulic pressure, which causes the retraction shaft 51 to be pushed down by the biasing force of the spring 52. As a result, the head portion 672 is gripped by the top member 55 provided near the opening of the retraction hole 511, and the retraction rod 67 is retracted downward, firmly connecting the upper unit 32 to the lower unit 31. The workpiece W sandwiched between the lower clamp block 47 and the upper clamp block 66 is then securely clamped.

In the work clamp device 30 that is ready to process the workpiece W, the rotation is transmitted to the spindle 42 via the worm gear 44 by driving the spindle motor 43, and in the lower unit 31, the configuration up to the lower clamp block 47 rotates integrally. Since the piston rod 531 in the state where the piston 53 is lowered is separated from the retraction shaft 51, the retraction shaft 51 and the spring 52 also rotate integrally with the spindle 42. In the upper unit 32, the retraction rod 67 gripped by the retraction shaft 51 and the upper clamp block 66 rotate while being supported by the shaft 65. Therefore, in the hobbing module 8, the hob 27, whose rotation is synchronized with the rotating workpiece W, moves in the Z-axis direction, and the outer periphery of the workpiece W is subjected to gear cutting.

After the gear cutting process, the work clamping device 30 releases the machined workpiece Wa as shown in Figure 8. Figure 8 is a cross-sectional view of the work clamping device 30 in a state in which the machined workpiece is being released, and in particular only the upper unit 32 is shown. When releasing the workpiece, hydraulic oil is first supplied from the port 541 into the cylinder portion 54, and the piston 53 is returned to the state shown in Figure 4. This pushes up the retraction shaft 51, and the retraction rod 67 is released from the piece member 55. Thereafter, the lift 34 is raised by the drive of the Z-axis servo motor 35, and the upper unit 32 separates from the lower unit 31, and the workpiece Wa is released from the clamped state.

In the work clamping device 30, the taper arbor 71 is tightly fitted into the central hole H of the work W by the spring 72 when clamping before machining, so that when the upper unit 32 rises after machining, the machined work Wa is lifted as shown in the figure. Conventionally, as shown by the dashed line, when the upper unit 32 rises, the machined work Wa is left on the lower clamp block 47 (lower unit 31). However, in this embodiment, since the machined work Wa is lifted, when the work transport robot 15 is used to remove it, the machined work Wa is grabbed from the bottom (opposite side), which is the opposite of the conventional method.

Therefore, according to this embodiment, even if the central hole H of the workpiece W is tapered, the tapered arbor 71 with the taper angle adjusted to the central hole H can be inserted into the central hole H to center the workpiece W during clamping. Moreover, since there is no driving part such as a chuck claw, the configuration is simpler and the cost can be reduced compared to the conventional chuck mechanism. Furthermore, since the machined workpiece Wa is lifted by the tapered arbor 71 fitted into the central hole H, the machined workpiece Wa can be transported to the next process in an inverted state by simply removing it with the work transport robot 15 without using an inverting device as in the conventional method. And, even if the dimensions of the workpiece W are different, it can be easily handled by replacing the upper clamp block 66 and the tapered arbor 71 with those that match the dimensions. Also, if it is not necessary to invert the machined workpiece Wa, it can be easily handled by replacing the upper clamp block 66 and the tapered arbor 71 with those that match the dimensions.

Although one embodiment of the present invention has been described, the present invention is not limited to this embodiment, and various modifications are possible without departing from the spirit of the present invention.
For example, in the above embodiment, a work clamping device constituting a hobbing machine has been described, but the work clamping device may be configured as a work clamping device for a grinding machine or the like.

Description of the Related Art 8... Hobbing machine module 15... Work transport robot 27... Hob 29... Control panel 30... Work clamping device 31... Lower unit 32... Upper unit 33... Support column 34... Lift 35... Z-axis servo motor 37... Hydraulic cylinder 41... Table 42... Spindle 43... Spindle motor 47... Lower clamp block 51... Retraction shaft 55... Piece member 53... Piston 54... Cylinder portion 65... Shaft 66... Upper clamp block 67... Retraction rod 71... Tapered arbor 72... Spring H... Center hole W... Work

Claims (3)

A lower unit in which a lower clamp block that supports the workpiece from below is rotated by a drive motor;
An upper unit in which an upper clamp block that holds a workpiece from above is rotatable by a rotation shaft coaxial with the lower clamp block;
a lift mechanism for raising and lowering the upper unit along a rotation axis;
an actuator that moves the upper unit in a rotation axis direction in a lifting portion of the lift mechanism;
an upper/lower unit connecting mechanism that pulls a pull rod on a rotating shaft protruding downward from the upper unit by gripping it inside the lower unit;
A tapered arbor into which the retraction rod is inserted and which is fitted into a tapered central hole of the workpiece by the biasing force of a biasing member;
A work clamping device having a clamping mechanism. The work clamping device according to claim 1, wherein the upper unit is a disassembly of the upper clamp block, the retracting rod, the tapered arbor, and the biasing member, which are assembled to the rotating shaft in a disassembly manner. The work clamping device according to claim 2, wherein the upper clamp block has a central portion with a through hole in the direction of the rotation axis, the retracting rod is fixed to the upper clamp block such that the flange portion covers the central portion from above, and the rod portion protrudes downward from the central portion, and the tapered arbor is inserted into the central portion of the upper clamp block with its downward movement restricted, and is biased downward by the biasing member.

Images