JP7704643B2 - Indexing Device - Google Patents

Description

The present invention relates to an indexing device equipped with a carbide mechanism and capable of automatically setting the origin of a servo motor.

One example of an indexing device that accurately indexes angles is a turret device for machine tools that selects and positions a specific tool from multiple tools. The turret device in Patent Document 1 below uses a curvic coupling, and in the clamped state, the teeth of the turret tool rest and the turret body are pressed firmly against each other. In this turret device, the appropriate tool is selected by rotational indexing, and the target tool is positioned by the engagement of the curvic coupling. During machining, the cutting tool is applied to the rotating workpiece to perform the specified machining. During this process, the tool experiences resistance when the workpiece is cut, but the tool is supported by the engaged curvic coupling.

JP 2006-15448 A

The turret device performs rotation index control by measuring the rotation angle from the origin set for the absolute encoder of the slewing index servomotor. In such a turret device, the origin of the slewing index servomotor is set by the operator rotating the tool post so that the mounting surface is at right angles to the vertical direction, and the rotation position where the curvic coupling engages is set as the origin. However, there is backlash between the meshing teeth, which cannot be seen directly because they are built into the turret device, and it is not possible to determine the rotation position so that the centers of the teeth and grooves are correctly overlapped. Therefore, when setting the origin of the slewing index servomotor, there is a large variation in the origin position depending on the operator, and there is also a large difference in the time it takes to complete the setting.

Therefore, the present invention aims to solve this problem by providing an indexing device that can automatically set the origin of a servo motor.

The indexing device according to the present invention includes an indexing rotor rotatably assembled so as to be covered by a housing, a servo motor equipped with an absolute encoder, a speed reducing mechanism incorporated in the housing for transmitting the rotation of the servo motor to the indexing rotor, a curvic coupling consisting of first and second curvic coupling pieces having a plurality of teeth arranged in an annular shape, and a rotation switching mechanism incorporated in the housing for switching between rotation and rotation restriction of the indexing rotor by clamping and unclamping the curvic coupling, and a drive control of the servo motor for the curvic coupling in the clamped state. and a control device having an automatic origin setting processing unit which moves the teeth of the first curvic coupling piece formed integrally with the indexing rotor in a clockwise and counterclockwise direction within a groove of the non-rotating second curvic coupling piece provided on the rotation switching mechanism side and brings them into contact with each of the teeth on both sides of the groove, thereby storing the rotation positions in both directions when the current supplied to the servo motor reaches a preset value, positions the teeth of the first curvic coupling piece at a central position calculated from the rotation positions in both directions, and sets the rotation position output from the absolute encoder at that time as an origin .

According to the above configuration, the automatic origin setting processing unit of the control device controls the drive of the servo motor when the curvilinear coupling is in the clamped state, the teeth of the first curvilinear coupling piece and the center of the groove of the second curvilinear coupling piece are aligned, and the rotational position output from the absolute encoder is set as the origin, eliminating variation in the origin position due to differences between operators and shortening the time required to complete the setting.

FIG. 1 is a cross-sectional view showing an embodiment of an index device. FIG. 2 is a front view of the turret head. FIG. 2 is a block diagram showing a control system of the turret device. FIG. 13 is an image diagram of an automatic origin setting process that is performed automatically. FIG. 13 is a flowchart showing an automatic origin setting process.

One embodiment of an index device according to the present invention will be described below with reference to the drawings. In this embodiment, a turret device constituting a machine tool will be described as an example of an index device. FIG. 1 is a cross-sectional view showing the turret device. The turret device 1 is configured so that the rotation output of a servo motor 2 for slewing indexing is transmitted to a turret head 3, and slewing indexing is performed for the turret head 3 to which multiple tools are attached. The internal mechanism of the turret device 1 is covered by housing members 11-16 assembled in the axial direction in the turret head 3.

The turret device 1 has a drive shaft 5 that is rotated by a slewing indexing servo motor 2, and a cylindrical extension member 7 is fixed coaxially to the drive shaft 5, allowing it to rotate around a rotation axis O within the housing member 11-16. Furthermore, a turret head 3 is fixed coaxially to the extension member 7. In the turret device 1, a parallel shaft gear reduction mechanism is incorporated within the housing member 11-16 to transmit the rotation of the slewing indexing servo motor 2 to the freely rotatable drive shaft 5.

The gear reduction mechanism first has a small-diameter motor gear 22 fixed to the motor shaft 21 of the rotation index servo motor 2, which meshes with a large-diameter first gear 23. A small-diameter second gear (not shown) is formed integrally with the first gear 23 on the same axis, and the second gear meshes with a large-diameter third gear 24. Furthermore, a small-diameter fourth gear 25 is formed coaxially with the third gear 24, and the fourth gear 25 meshes with a fifth gear 26 fixed to the drive shaft 5.

When the turret device 1 is driven and controlled by the servo motor 2 for slewing indexing, the drive shaft 5 is given a reduced rotation through a series of meshing gears. The turret head 3, which is fixed to the drive shaft 5 through an extension member 7, is then rotated at a predetermined angle, and the tool to be used for machining the workpiece is slewingly indexed from among the multiple tools attached to the turret head 3. In the turret device 1, the turret head 3 is positioned by a curvic coupling, since the tool selected in this way experiences resistance during machining. The turret head 3 in this embodiment is decagonal as shown in FIG. 2, and tools (not shown) can be attached and detached to each side via tool holders.

The carbide coupling is composed of a rotating carbide coupling piece 31 that rotates together with the drive shaft 5 and a fixed carbide coupling piece 32 that is assembled to a carbide coupling cylinder formed around the drive shaft 5. The rotating carbide coupling piece 31 is assembled so as to be sandwiched between the drive shaft 5 and the extension member 7, and has teeth that face the drive shaft 5 side formed in a ring shape. The fixed carbide coupling piece 32 is fixed together with the piston 33 so as to be overlapped in the axial direction, and has teeth that are also formed in a ring shape to mesh with the teeth of the rotating carbide coupling piece 31.

The carbide hydraulic cylinder is formed with a clamping pressure chamber 35 and an unclamping pressure chamber 36 on either side of the piston 33, and the piston 33 can be displaced along the axial direction of the rotation axis O by supplying and discharging hydraulic oil. In the clamping pressure chamber 35, multiple pins 37 parallel to the rotation axis O are protruding from the piston 33. Meanwhile, a non-rotating cylinder block 39 fixed to the housing member 14 side is formed with positioning holes, into which the pins 37 are inserted to limit the rotation of the piston 33 and the fixed side carbide coupling piece 32. Coil springs 38 are provided around each pin 37, and the piston 33 is biased toward the rotating side carbide coupling piece 31.

In the turret device 1, multiple tools attached to the turret head 3 are selected by arm rotation indexing during workpiece machining and positioned at a position where machining is possible. The drive control of the servo motor 2 for slewing indexing is performed by sending a rotation position command signal from the machine tool's control device, which is converted into servo pulses by a servo amplifier. These servo pulses are created based on a feedback signal from the encoder of the servo motor 2 for slewing indexing. This causes the turret head 3 to stop at a specified rotation position, and slewing indexing of the tool to be used for machining is performed.

The rotation output of the servo motor 2 for slewing indexing is transmitted by reducing the rotation of the motor gear 22 from the first gear 23 to the second gear, and then to the third gear 24, the fourth gear 25, and the fifth gear 26. Therefore, the drive shaft 5 and the turret head 3 rotate by a predetermined angle by the rotation control of the servo motor 2 for slewing indexing, and the corresponding tool is slewing indexed. At this time, hydraulic oil is supplied to the unclamping side pressure chamber 36 of the curvilinear cylinder, and the piston 33 is displaced toward the servo motor 2 for slewing indexing, and the engagement between the rotating side curvilinear coupling piece 31 and the fixed side curvilinear coupling piece 32 is released.

After the tool has been rotated and indexed, hydraulic oil is supplied to the clamping pressure chamber 35 while hydraulic oil is discharged from the unclamping pressure chamber 36, and the piston 33 is displaced toward the turret head 3. This causes the fixed curvic coupling piece 32 to mesh with the rotating curvic coupling piece 31, restricting the rotation of the turret head 3. The corresponding tool is fixed at the machining position, and machining of the workpiece becomes possible.

The turret device 1 uses an encoder to measure the rotation angle from a set origin to accurately index the tool, and controls the drive of the swivel indexing servo motor 2. An absolute encoder 55 (see Figure 3) is used for the swivel indexing servo motor 2 of the turret device 1, which is NC controlled, and outputs not only pulse samples according to the amount of motor rotation but also absolute position signals as rotation position command signals. Therefore, the turret device 1 sets an origin to operate with rotation position data based on the origin.

In setting the origin, the turret head 3 is rotated by the operator in an unclamped state where the rotating curvilinear coupling piece 31 and the fixed curvilinear coupling piece 32 are separated. For example, as shown in FIG. 2, the first tool attachment part 301 is positioned at the top, and its attachment surface is positioned perpendicular to the vertical reference line L. Then, the rotating curvilinear coupling piece 31 and the fixed curvilinear coupling piece 32 are engaged, and fine adjustment is made for backlash, and the rotational position is set as the origin. Conventionally, this fine adjustment was performed manually by the operator. However, since this is work on a part of the housing that cannot be directly seen, there is variation in accuracy from operator to operator, and the work time required for setting also varies greatly depending on experience.

In this regard, in this embodiment, the final origin setting is configured to be performed automatically. 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 memory unit 52 that stores information generated in response to the processing, and is configured to control the driving of the servo motor 2 for turning indexing and the driving of the hydraulic circuit 56 of the hydraulic cylinder for curvilinear motion.

Figure 4 is an image diagram of the automatic origin setting process, showing the meshing teeth of the rotating curvic coupling piece 31 and the fixed curvic coupling piece 32. Also, Figure 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 executed according to an origin setting signal transmitted from the operation display device 57 of the machine tool by the operator after the turret head 3 is positioned at the rotation position shown in Figure 2 as described above.

The angular position of the turret head 3 where the first tool attachment portion 301 is perpendicular to the vertical reference line L is set as the origin. In this case, as shown in FIG. 4(A), a misalignment occurs between the center lines M1, M2 of the teeth 41 of the rotating curvic coupling piece 31 and the groove 42 of the fixed curvic coupling piece 32. As described above, it is difficult to manually correct this misalignment, so in this embodiment, automatic adjustment and origin setting are performed. In the automatic origin setting process, first, the rotation indexing servo motor 2 is driven to rotate the rotating curvic coupling piece 31 clockwise (to the right in the drawing) at a very slow speed (check speed) (S101).

At this time, as shown in FIG. 4B, the teeth 41 of the rotating curvilinear coupling piece 31 move clockwise in the groove 42 of the fixed curvilinear coupling piece 32 by the amount of the gap caused by the backlash. Then, the teeth 41 of the rotating curvilinear coupling piece 31 come into contact with the teeth 43 of the fixed curvilinear coupling piece 32 at a very slow speed. Therefore, the current supplied to the rotation indexing servo motor 2, which is loaded by the teeth 41 and 43 coming into contact with each other, gradually increases. This current is confirmed in the automatic origin setting process, and a determination is made as to whether the supplied current exceeds the rated X% (X is an arbitrary value) (S102).

If the supply current does not reach X% of the rated current (S102: NO), the clockwise rotation of the rotating curvilinear coupling piece 31 and the determination of the current value are continued (S101, S102). If the supply current then reaches X% of the rated current (S102: YES), the rotational position W1 is recorded in the memory unit 52 of the control device 50 (S103). In this measurement, the rotating curvilinear coupling piece 31 is rotated by the gap in microns due to backlash, and the rotational position W1 is determined based on the change in the current value that occurs at that time. Therefore, the confirmation speed is a very slow speed that makes it possible to determine the rotational position at such an extremely small distance. For example, in this embodiment, it is a speed of about 1% of normal operation.

Then, the drive of the rotation indexing servo motor 2 is switched, and the rotating curvilinear coupling piece 31 is rotated counterclockwise (to the left in the drawing) at a very slow confirmation speed (S104). Therefore, as shown in FIG. 4(C), the tooth 41 of the rotating curvilinear coupling piece 31 moves within the groove 42 of the fixed curvilinear coupling piece 32 and contacts the tooth 44 on the opposite side.

Here too, the load caused by the teeth 41 of the rotating curvilinear coupling piece 31 hitting the teeth 44 of the fixed curvilinear coupling piece 32 gradually increases the current supplied to the rotation indexing servo motor 2. Therefore, the current value is confirmed, and a determination is made as to whether the supplied current exceeds X% of the rated current (S105). If the supplied current does not reach X% of the rated current (S105: NO), clockwise rotation of the rotating curvilinear coupling piece 31 and determination of the current value are continued (S104, S105). Thereafter, if the supplied current reaches X% of the rated current (S105: YES), the rotation position W2 is recorded in the memory unit 52 of the control device 50 (S106).

Next, the center position W between the rotational position W1 and the rotational position W2 read from the memory unit 52 is calculated (S107). The center position W is the center of the groove 42 of the fixed side curvic coupling piece 32. Then, the rotational side curvic coupling piece 31 is rotated clockwise from the rotational position W2 by the drive control of the rotation indexing servo motor 2, and alignment at the center position W is performed (S108). That is, as shown in FIG. 4(D), the center line M1 of the tooth 41 is overlapped with the center line M2 of the groove 42. Then, the rotational 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 memory unit 52 of the control device 50 (S109).

Therefore, according to this embodiment, the origin setting is performed automatically, eliminating variation in the origin position due to differences in operators and shortening the time required to complete setting. Furthermore, these effects can be obtained through control without making any structural improvements to the conventional turret device.

Although one embodiment of the present invention has been described above, 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, the turret device 1 has been taken as an example for explanation, but the present invention is also applicable to other index devices.

Reference Signs List 1: turret device 2: rotation indexing servo motor 3: turret head 5: drive shaft 11-16: housing member 22-26: gear 31: rotation side curvilinear coupling piece 32: fixed side curvilinear coupling piece 33: piston 35: clamp side pressure chamber 36: unclamping side pressure chamber 50: control device 52: memory unit 55: absolute encoder

Claims (3)

an indexing rotor rotatably mounted so as to be covered by the housing;
A servo motor equipped with an absolute encoder;
A reduction mechanism incorporated in the housing for transmitting rotation of the servo motor to the indexing rotor;
a rotation switching mechanism incorporated in the housing, the rotation switching mechanism including a curvilinear coupling having first and second curvilinear coupling pieces each having a plurality of teeth arranged in an annular shape, the rotation switching mechanism switching between rotation and rotation restriction of the indexing rotor by clamping and unclamping the curvilinear coupling;
a control device including an automatic origin setting processing unit which, by controlling the drive of the servo motor for the curvic coupling in a clamped state , moves the teeth of the first curvic coupling piece formed integrally with the indexing rotor in a clockwise and counterclockwise direction in a groove of the non-rotating second curvic coupling piece provided on the rotation switching mechanism side, and abuts against each tooth on both sides of the groove, stores the rotation positions in both directions when the current supplied to the servo motor reaches a preset value, positions the teeth of the first curvic coupling piece at a center position calculated from the rotation positions in both directions, and sets the rotation position output from the absolute encoder at that time as an origin;
An indexing device having: 2. The indexing 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 curvature coupling piece is fixed to the piston. 3. The indexing device according to claim 1, wherein the automatic origin setting processing unit moves the teeth of the first curvic coupling piece within the groove of the second curvic coupling piece at a very slow confirmation speed different from that during normal operation .

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