Index device

Abstract

To provide an index device capable of performing automatic origin setting processing of a servo motor.SOLUTION: An index device includes: an indexing rotary body rotatably assembled so as to be covered with the housing; a servo motor having an absolute encoder; a speed reduction mechanism assembled into the housing to transmit the rotation of the servo motor to the indexing rotary body; a rotation switching mechanism including a curvic coupling comprising first and second curvic coupling pieces, switching between the rotation and the rotation limit of the indexing rotary body, and assembled into a housing; and a control device which includes an automatic origin setting processing section for coinciding the teeth of the first curvic coupling piece with the center of the groove of the second curvic coupling piece by drive control of the servo motor from a clamp state of the curvic coupling, and setting a rotation position output from the absolute encoder as an origin.SELECTED DRAWING: Figure 4

Description

Technical Field

[0001] The present invention relates to an indexing device provided with a cam mechanism and capable of automatically setting the origin of a servo motor.

Background Art

[0002] For example, an indexing device for accurately determining an angle includes a turret device of a machine tool that selects and positions a predetermined tool from a plurality of tools. The turret device of Patent Document 1 below uses a cam coupling, and in the clamped state, the tooth portions of the turret tool rest and the turret body strongly press against each other. In that turret device, the corresponding tool is selected by rotational indexing, and the positioning of the target tool is performed by the engagement of the cam coupling. During machining, a predetermined machining is performed, such as applying a cutting tool to a rotating workpiece. At that time, the tool receives resistance from the workpiece cutting, but the tool is supported by the engaged cam coupling.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] The indexing control of the turret device is performed by measuring the rotation angle from the origin set for the absolute encoder of the servo motor for indexing rotation. The origin setting of the servo motor for indexing rotation in such a turret device is such that the operator rotates the tool rest to a position where the mounting surface is orthogonal to the vertical direction, and the engaged rotational position of the curvic coupling is set as the origin. However, there is backlash between the meshing teeth, and since it is particularly incorporated inside the turret device, it cannot be directly seen, and the rotational position cannot be determined so that the center of the tooth and the groove are correctly aligned. Therefore, in the origin setting of the servo motor for indexing rotation, there is a large variation in the origin position due to differences among operators, and there is also a large difference in the time until the setting is completed.

[0005] Therefore, an object of the present invention is to provide an indexing device capable of automatically setting the origin of a servo motor in order to solve such problems.

Means for Solving the Problems

[0006] The indexing device according to the present invention includes an indexing rotating body rotatably assembled so as to be covered by a housing, a servo motor provided with an absolute encoder, a speed reduction mechanism incorporated in the housing for transmitting the rotation of the servo motor to the indexing rotating body, and a curvic coupling composed of first and second curvic coupling pieces in which a plurality of teeth are arranged annularly, and a rotation switching mechanism incorporated in the housing for switching between the rotation and rotation limitation of the indexing rotating body by its clamping and unclamping. For the curvic coupling in the clamped state By the drive control of the servo motor, The teeth of the first curvic coupling piece integrally formed with the indexing rotator are moved clockwise and counterclockwise in the groove of the non-rotating second curvic coupling piece provided on the rotation switching mechanism side, and by abutting against each tooth on both sides of the groove, the rotational positions in both directions when the current supplied to the servomotor reaches a preset value are memorized, the teeth of the first curvic coupling piece are positioned at the central position calculated from the rotational positions in both directions, and the rotational position output from the absolute encoder at that time is set as the origin it has a control device provided with an automatic origin setting processing unit.

Effects of the Invention

[0007] According to the above configuration, the automatic origin setting unit of the control device drives and controls the servomotor when the curvic coupling is in the clamped state, so that the teeth of the first curvic coupling piece coincide with the center of the groove of the second curvic coupling piece, and the rotation position output from the absolute encoder is set as the origin. Therefore, the variation in the origin position due to differences among operators is eliminated, and the time required to complete the setting can also be shortened.

Brief Description of the Drawings

[0008]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Embodiments for Carrying Out the Invention

[0009] An embodiment of the index device according to the present invention will be described below with reference to the drawings. In this embodiment, as an example of the index device, a turret device that constitutes a machine tool will be described. FIG. 1 is a cross-sectional view showing the turret device. The turret device 1 is configured such that the rotational output of the servomotor 2 for swing indexing is transmitted to the turret head 3, and swing indexing of the turret head 3 to which a plurality of tools are attached is performed. The turret head 3 has its internal mechanism of the turret device 1 covered by housing members 11 - 16 assembled in the axial direction.

[0010] The turret device 1 has a drive shaft 5 that rotates by a servo motor 2 for swing indexing. A cylindrical extension member 7 is coaxially fixed to the drive shaft 5, and is configured to be rotatable about a rotation axis O within housing members 11 - 16. Further, a turret head 3 is coaxially fixed to the extension member 7. The turret device 1 incorporates a parallel-axis gear reduction mechanism within the housing members 11 - 16 in order to transmit the rotation of the servo motor 2 for swing indexing to the rotatable drive shaft 5.

[0011] The gear reduction mechanism first has a small-diameter motor gear 22 fixed to the motor shaft 21 of the servo motor 2 for swing indexing, which meshes with a large-diameter first gear 23. A small-diameter second gear (not shown) is integrally formed coaxially with the first gear 23, and the second gear meshes with a large-diameter third gear 24. Further, a small-diameter fourth gear 25 is coaxially formed on the third gear 24, and the fourth gear 25 meshes with a fifth gear 26 fixed to the drive shaft 5.

[0012] Therefore, when rotation is output by drive control of the servo motor 2 for swing indexing in the turret device 1, the drive shaft 5 is given a decelerated rotation via a series of meshing gears. Then, a rotation of a predetermined angle is given to the turret head 3 fixed to the drive shaft 5 via the extension member 7, and swing indexing of the tool used for workpiece machining is performed from a plurality of tools attached to the turret head 3. Since the tool thus selected receives resistance during machining, the turret head 3 is positioned by a curvic coupling. Note that the turret head 3 of the present embodiment is decagonal as shown in FIG. 2, and tools (not shown) can be detachably attached to each side via tool holders.

[0013] The bevel coupling is composed of a rotating-side bevel coupling piece 31 that rotates integrally with a drive shaft 5 or the like, and a fixed-side bevel coupling piece 32 assembled to a bevel coupling cylinder formed around the drive shaft 5. The rotating-side bevel coupling piece 31 is incorporated so as to be sandwiched between the drive shaft 5 and the extension member 7, and teeth facing the drive shaft 5 side are formed in an annular shape. The fixed-side bevel coupling piece 32 is integrally fixed so as to be axially overlapped with the piston 33, and teeth are also formed in an annular shape so as to mesh with the teeth of the rotating-side bevel coupling piece 31.

[0014] In the bevel hydraulic cylinder, a clamp-side pressure chamber 35 and an unclamp-side pressure chamber 36 are formed so as to sandwich the piston 33, and the piston 33 can be displaced along the axial direction of the rotation axis O by the supply and discharge of hydraulic oil. Further, a plurality of pins 37 parallel to the rotation axis O project from the piston 33 into the clamp-side pressure chamber 35. On the other hand, positioning holes are formed in the non-rotating cylinder block 39 fixed to the housing member 14 side, and the rotation of the piston 33 and the fixed-side bevel coupling piece 32 is restricted by inserting the pins 37 thereinto. And coil springs 38 are provided around each pin 37, and the piston 33 is biased toward the rotating-side bevel coupling piece 31 side.

[0015] In the turret device 1, a plurality of tools attached to the turret head 3 are selected by arm rotation indexing during workpiece machining and positioned at positions where machining is possible. The drive control of the rotation indexing servo motor 2 is such that a rotation position command signal is transmitted from the control device of the machine tool and converted into servo pulses by the servo amplifier. The servo pulses are created based on the feedback signal from the encoder of the rotation indexing servo motor 2. Thereby, the turret head 3 stops at a predetermined rotation position, and the rotation indexing of the tool used for machining is performed.

[0016] The rotational output of the servo motor 2 for swing indexing is transmitted with the rotation of the motor gear 22 decelerated through the first gear 23 to the second gear, and further to the third gear 24, the fourth gear 25, and the fifth gear 26. Accordingly, by controlling the rotation of the servo motor 2 for swing indexing, the drive shaft 5 and the turret head 3 rotate by a predetermined angle, and the swing indexing of the corresponding tool is performed. At this time, the operating oil is supplied to the unclamping side pressure chamber 36 of the curvic cylinder, the piston 33 is displaced toward the servo motor 2 for swing indexing side, and the engagement between the rotating side curvic coupling piece 31 and the fixed side curvic coupling piece 32 is released.

[0017] After the swing indexing of the tool is completed, the operating oil is supplied to the clamping side pressure chamber 35 while the operating oil in the unclamping side pressure chamber 36 is discharged, and the piston 33 is displaced toward the turret head 3 side. Thereby, the fixed side curvic coupling piece 32 engages with the rotating side curvic coupling piece 31, and the rotation of the turret head 3 is restricted. The corresponding tool is fixed at the machining position, and machining of the workpiece becomes possible.

[0018] In order to swing index the corresponding tool to an accurate position, the turret device 1 performs drive control of the servo motor 2 for swing indexing by measuring the rotation angle from the set origin with an encoder. An absolute encoder 55 (see Fig. 3) is used for the servo motor 2 for swing indexing of the turret device 1 where NC control is performed, and not only a pulse example corresponding to the rotation amount of the motor but also an absolute position signal are output as the rotation position command signal. Therefore, in the turret device 1, origin setting for operating with rotation position data based on the origin is performed.

[0019] In the origin setting, the turret head 3 is rotated by the operator in an unclamped state where the rotating-side curvic coupling piece 31 and the fixed-side curvic coupling piece 32 are separated. For example, as shown in FIG. 2, the first tool mounting portion 301 is positioned at the top, and positioning is performed such that its mounting surface is orthogonal to the vertical reference line L. Then, the rotating-side curvic coupling piece 31 and the fixed-side curvic coupling piece 32 are engaged, and further fine adjustment for backlash is performed, and its rotational position is set as the origin. Conventionally, this fine adjustment was manually performed by the operator. However, since it is work on a part that cannot be directly seen inside the housing, there is a variation in accuracy for each person in charge, and the work time until setting also had a large difference depending on experience.

[0020] In this regard, in the present embodiment, the final origin setting is configured to be automatically performed. FIG. 3 is a block diagram showing the control system of the turret device 1. The control device 50 of the machine tool has an automatic origin setting processing unit 51 in which an origin setting program is stored and a storage unit 52 that stores information generated according to the processing, and is configured to control the drive of the swing detection servo motor 2 and the drive of the hydraulic circuit 56 of the curvic hydraulic cylinder.

[0021] FIG. 4 is an image diagram of the automatic origin setting process performed automatically, showing the meshing teeth of the rotating-side curvic coupling piece 31 and the fixed-side curvic coupling piece 32. Further, FIG. 5 is a diagram showing a flowchart of the automatic origin setting process. The automatic origin setting process executed by the origin setting program stored in the automatic origin setting processing unit 51 is performed with the turret head 3 positioned at the rotational position shown in FIG. 2 as described above, and is executed according to the origin setting signal transmitted from the operation display device 57 of the machine tool by the operator's operation.

[0022] The angular position of the turret head 3 where the first tool attachment portion 301 is orthogonal to the vertical reference line L is set as the origin. In that case, as shown in Fig. 4(A), a deviation occurs between the center lines M1 and M2 of the teeth 41 of the rotating-side spherical coupling piece 31 and the groove 42 of the fixed-side spherical coupling piece 32. Since it is difficult to correct this deviation manually as described above, in this embodiment, automatic adjustment and origin setting are performed. In the automatic origin setting process, first, by driving the swing detection servo motor 2, the rotating-side spherical coupling piece 31 is rotated at a very slow speed (confirmation speed) in the clockwise direction (right direction in the drawing) (S101).

[0023] At this time, as shown in Fig. 4(B), the teeth 41 of the rotating-side spherical coupling piece 31 move clockwise in the groove 42 of the fixed-side spherical coupling piece 32 by the amount of clearance due to backlash. Then, the rotating-side spherical coupling piece 31 has its teeth 41 gently applied to the teeth 43 of the fixed-side spherical coupling piece 32 at a very slow speed. Therefore, the swing detection servo motor 2 that receives a load when the teeth 41 and 43 hit each other has the supplied current gradually increase. In the automatic origin setting process, this current is checked, and it is determined whether the supply current exceeds X% of the rated value (X is an arbitrary value) (S102).

[0024] If the supply current does not reach X% of the rated value (S102: NO), the clockwise rotation of the rotating-side spherical coupling piece 31 and the determination of the current value are continued (S101, S102). After that, when the supply current reaches X% of the rated value (S102: YES), the rotation position W1 is recorded in the storage unit 52 of the control device 50 (S103). Incidentally, such measurement rotates the rotating-side spherical coupling piece 31 by the amount of clearance in micron units due to backlash, and the rotation position W1 is obtained based on the change in the current value generated at that time. Therefore, the confirmation speed is a very slow speed that enables the determination of the rotation position at such an extremely small distance. For example, in this embodiment, it is about 1% of the normal operation speed.

[0025] Subsequently, the drive of the servo motor 2 for turning determination is switched, and a very slow rotation in the counterclockwise direction (left direction in the drawing) is given to the rotary side curved coupling piece 31 at a confirmation speed (S104). Therefore, as shown in FIG. 4(C), the teeth 41 of the rotary side curved coupling piece 31 move within the groove 42 of the fixed side curved coupling piece 32 and come into contact with the teeth 44 on the opposite side.

[0026] Here too, due to the load where the teeth 41 of the rotary side curved coupling piece 31 hit the teeth 44 of the fixed side curved coupling piece 32, the current supplied to the servo motor 2 for turning determination gradually increases. Thus, the current value is checked, and a determination is made as to whether the supply current exceeds X% of the rated value (S105). If the supply current does not reach X% of the rated value (S105: NO), the rotation of the rotary side curved coupling piece 31 in the clockwise direction and the determination of the current value are continued (S104, S105). After that, when the supply current reaches X% of the rated value (S105: YES), the rotation position W2 is recorded in the storage unit 52 of the control device 50 (S106).

[0027] Next, the central position W between the rotation position W1 read from the storage unit 52 and the rotation position W2 is calculated (S107). The central position W is the center of the groove 42 of the fixed side curved coupling piece 32. Therefore, by driving and controlling the servo motor 2 for turning determination, a rotation in the clockwise direction from the rotation position W2 is given to the rotary side curved coupling piece 31, and alignment is performed at the central position W (S108). That is, as shown in FIG. 4(D), the center line M1 of the teeth 41 is overlapped with the center line M2 of the groove 42. Then, the rotation position output from the absolute encoder 55 in the state where the center lines M1 and M2 shown in FIG. 4(D) are overlapped is set as the origin and stored in the storage unit 52 of the control device 50 (S109).

[0028] Therefore, according to this embodiment, since the origin setting is automatically performed, the variation in the origin position due to differences among operators is eliminated, and the time until the setting is completed can also be shortened. In addition, such an effect can be obtained by control without improving the structure from the conventional turret device.

[0029] As described above, one embodiment of the present invention has been described. However, the present invention is not limited to this, and various modifications are possible without departing from the spirit thereof. For example, in the above embodiment, the turret device 1 has been described as an example, but it can also be applied to other index devices.

Explanation of Reference Numerals

[0030] 1... Turret device 2... Servo motor for swing determination 3... Turret head 5... Drive shaft 11 - 16... Housing members 22 - 26... Gears 31... Rotating side curvic coupling piece 32... Fixed side curvic coupling piece 33... Piston 35... Clamping side pressure chamber 36... Unclamping side pressure chamber 50... Control device 52... Storage unit 55... Absolute encoder

Claims

1. An indexing rotor rotatably assembled so as to be covered by a housing, A servo motor provided with an absolute encoder, A speed reduction mechanism incorporated in the housing for transmitting the rotation of the servo motor to the indexing rotor, A cubic coupling comprising first and second cubic coupling pieces having a plurality of teeth arranged annularly, and a rotation switching mechanism incorporated in the housing for switching between rotation and rotation limitation of the indexing rotor by clamping and unclamping thereof, By driving control of the servo motor with respect to the cubic coupling in the clamped state, the teeth of the first cubic coupling piece integrally formed with the indexing rotor are moved clockwise and counterclockwise in the groove of the non-rotating second cubic coupling piece provided on the rotation switching mechanism side, and by hitting each tooth on both sides of the groove, when the current supplied to the servo motor reaches a preset value, the rotational positions in both directions are memorized, the teeth of the first cubic coupling piece are positioned at the central position calculated from the rotational positions in both directions, and a control device having an automatic origin setting processing unit for setting the rotational position output from the absolute encoder at that time as the origin, An index device having the above.

2. The index device according to claim 1, wherein the rotation switching mechanism has a hydraulic cylinder that displaces a non-rotating piston in the axial direction of the indexing rotor, and the second cubic coupling piece is fixed to the piston.

3. The index device according to claim 1 or claim 2, wherein the automatic origin setting processing unit moves the teeth of the first cubic coupling piece in the groove of the second cubic coupling piece at a very slow confirmation speed different from that during normal operation.

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