JP5242525B2 - Cylinder device and machine tool provided with the cylinder device - Google Patents

Description

  The present invention relates to a cylinder device capable of reducing sliding resistance at the time of starting and a machine tool including the cylinder device.

  Normally, a cylinder device as an actuator has a piston incorporated in a cylinder body, and the piston linearly moves by switching the pressures of both cylinder chambers partitioned by the piston. The cylinder device is provided with a contact type seal ring between the cylinder body and the piston and between the cylinder body and the piston rod in order to prevent leakage of a pressure medium (for example, air or oil) in the cylinder chamber (for example, , See Patent Document 1).

  As shown in Patent Document 1, a balance cylinder is often used on the vertical axis of a machine tool such as a machining center in order to balance the weight of a moving body. The cylinder device described in Patent Document 1 balances weight by applying a certain pressure to one cylinder chamber of the cylinder device. A ball screw, a linear motor, or the like is used to drive the vertically moving body.

  Further, as a balance cylinder of a machine tool, a cylinder device in which a cylinder rod having a pressure receiving portion smaller in diameter than a cylinder inner diameter is provided in a cylinder body and high-pressure gas is sealed inside is also known (for example, Patent Documents). 2). In the cylinder device described in Patent Document 2, a contact-type seal ring is provided between the cylinder body and the cylinder rod to prevent high-pressure gas from leaking.

JP-A-9-192957 JP 2000-153418 A

  In the conventional cylinder device, the sliding resistance of the seal ring is greatly different between when the piston starts to move from a stopped state (when starting) and when the piston is moving. For example, in a conventional cylinder device, minute step positioning is difficult in the case of a positioning device that uses a cylinder for driving.

  Further, as shown in the above-mentioned patent document, when the cylinder device is used as a balance cylinder on the vertical axis of a machine tool or the like, the sliding resistance of the seal ring causes stick-slip, which increases the operation accuracy of the machine tool. There was a problem of affecting.

  The cylinder device described in Patent Document 1 is replenished with lubricating oil so as not to lose lubrication even during long-term operation. However, even the cylinder device described in Patent Document 1 cannot reduce the sliding resistance when the piston starts to move from the stopped state, and stick-slip occurs at the time of starting or reversing the piston.

  Therefore, the present invention reduces the sliding resistance of the seal portion, and in particular, a cylinder device that can reduce the sliding resistance at the start of the movement of the rod and the piston from a stopped state, and a machine equipped with the cylinder device. Provide machines.

  The inventor of the present application explains that the cause of stick slip is that the lubricating oil contributes to lubrication while the rod or piston is moving, while the lubricating oil is not lubricated while the rod or piston is stopped. It was thought that the sliding resistance was increased. The inventor of the present application can lubricate the lubricating oil by constantly rotating the rod and the piston, can reduce the sliding resistance at the start, and can suppress the occurrence of stick-slip. I found it.

In order to solve the above-mentioned problems, the present invention is used as a balancer for a vertical drive shaft of a machine tool, is filled with a high-pressure gas, is closed at both ends, and one end is positioned in the cylinder body. A rod member having the other end protruding outward from the end surface of the cylinder body, a pressure receiving member provided at one end of the rod member, and capable of reciprocating along the axial direction in the cylinder body, and the cylinder body. A cylinder device for use in a machine tool, the axial direction of the rod member and the pressure receiving member with respect to the cylinder main body, the lubricating oil supplied to a contact portion with the pressure receiving member or / and the rod member independently of the reciprocating along, et al used a machine tool having a rotation drive mechanism that relatively rotates the rod member and the pressure receiving member to the cylinder body There is provided a that cylinder device.

Further, the cylinder device of the present invention, between the sides of the rod member and the cylinder body, and said cylinder body and Ri Oh provided a seal ring between the side surface of the pressure receiving member, a high pressure gas at one of the cylinder chambers Is enclosed .

  In the cylinder device of the present invention, a seal ring is provided between the cylinder body and the side surface of the rod member, and a gap is provided between the cylinder body and the side surface of the pressure receiving member.

  In the cylinder device of the present invention, the rotational drive mechanism includes a thrust bearing that restricts movement in the axial direction.

  In addition, the present invention provides a machine tool including a moving body that moves in the vertical direction by a driving means, and includes any one of the cylinder devices described above.

  A cylinder device according to the present invention includes a cylindrical cylinder body having both ends closed, a rod member having one end positioned in the cylinder body and the other end projecting outward from an end surface of the cylinder body, and the rod member A cylinder device comprising a pressure receiving member provided at one end and capable of reciprocating along the axial direction in the cylinder body, wherein the rod member and the pressure receiving member rotate relative to the cylinder body. By having a structure with a drive mechanism, even when the rod member and the pressure receiving member do not move in the axial direction with respect to the cylinder body, the lubrication of the contact portion such as the seal ring is maintained by the rotation of the rod member and the pressure receiving member. can do. As a result, the sliding resistance at the start of the movement of the rod member and the pressure receiving member can be reduced, and the sliding resistance at the time of starting or reversing is almost equal to the sliding resistance during continuous movement, and the occurrence of stick-slip occurs. It can be greatly suppressed. In addition, the cylinder device of the present invention is capable of minute positioning, and has an effect of enabling good position control and high-precision operation.

  In the cylinder device of the present invention, the seal ring is provided between the cylinder body and the side surface of the rod member, and between the cylinder body and the side surface of the pressure receiving member. The sliding resistance between the cylinder body and the pressure receiving member can be reduced.

  In the cylinder device of the present invention, a seal ring is provided between the cylinder body and the side surface of the rod member, and a gap is provided between the cylinder body and the side surface of the pressure receiving member. There is an effect that it is possible to reduce the sliding resistance between the rod member that is in contact with the ring.

  In the cylinder device according to the present invention, since the rotation drive mechanism includes a thrust bearing that restricts movement in the axial direction, the rod member and the pressure receiving member can be smoothly rotated. In addition, the movement in the axial direction can be restricted and good position control and high-precision operation can be achieved.

  Further, the machine tool of the present invention is a machine tool provided with a moving body that moves up and down by a driving means, and has a configuration including any one of the cylinder devices described above, thereby generating stick slip of the cylinder device. Therefore, the positioning can be performed minutely, and there is an effect that good position control and high-precision machining can be performed.

The block diagram which shows one Example of the cylinder apparatus which concerns on this invention. The block diagram which shows the principal part of the one Example. The block diagram which shows the other Example of the cylinder apparatus which concerns on this invention. The block diagram which shows one Example of the machine tool provided with the cylinder apparatus which concerns on this invention.

Embodiments of the present invention will be described based on examples shown in the drawings.
The cylinder device according to the present invention includes a cylindrical cylinder body 11 having both ends closed, a rod member 12 having one end positioned in the cylinder body 11 and the other end protruding outward from an end surface of the cylinder body 11. And a pressure receiving member 13 provided at one end of the rod member 12 and capable of reciprocating along the axial direction in the cylinder body 11. The rod member 12 and the pressure receiving member 13 are connected to the cylinder body 11. A rotation drive mechanism 20 that rotates relatively is provided.

FIG. 1 is a block diagram showing an embodiment of a cylinder device 10 according to the present invention.
The cylinder body 11 has a cylindrical shape with both ends closed, and is fixed to the moving body 30. The rod member 12 is formed of a rod-like body provided coaxially with the cylinder body 11 and is inserted through one end face of the cylinder body 11. One end of the rod member 12 is located in the cylinder body 11, and the other end protrudes from the end surface of the cylinder body 11 to the outside.

  The pressure receiving member 13 is a cylindrical piston provided coaxially with the cylinder body 11 in the cylinder body 11, and is fixed to one end of the rod member 12. A groove is formed on the side surface of the pressure receiving member 13 along the outer periphery. The groove portion is provided with a seal ring 14 that contacts the inner peripheral surface of the cylinder body 11 to prevent leakage of the pressure medium in the cylinder chamber.

  Further, the cylinder body 11 has a groove portion formed on the sliding surface with the rod member 12 along the inner periphery. A seal ring 15 that contacts the outer peripheral surface of the rod member 12 is provided in the groove portion to prevent leakage of the pressure medium in the cylinder chamber. The rod member 12 is fixed to the base 40 so as to be rotatable via the rotation drive mechanism 20 at the end portion protruding from the end surface of the cylinder body 11 to the outside.

  The cylinder body 11 is partitioned into a head side cylinder chamber 16 and a rod side cylinder chamber 17 by a pressure receiving member 13 and a seal ring 14. The cylinder device 10 is provided with a pressure control mechanism (not shown). By switching the pressures of the cylinder chambers 16 and 17, the pressure receiving member (piston) 13 moves linearly with respect to the cylinder body 11, and the moving body 30 is moved. Can be driven.

FIG. 2 is an enlarged configuration diagram showing details of the rotation drive mechanism 20.
In the illustrated embodiment, the rotary drive mechanism 20 includes a motor 23, a speed reducer 24, a drive gear 25, and a driven gear 26. The motor 23 is connected to a drive gear 25 via a speed reducer 24, and the drive gear 25 is provided so as to be screwed to a driven gear 26 fixed to the end of the rod member 12. The rotation of the motor 23 is moderately decelerated by the speed reducer 24 and further decelerated by the gear ratio of the drive gear 25 and the driven gear 26 so that the driven gear 26 rotates at a predetermined rotational speed.

  The rotation drive mechanism 20 includes a thrust bearing 22 that restricts the movement of the rod member 12 in the axial direction.

  The end of the rod member 12 is formed with a stepped portion 12a to have a small diameter, and a thrust bearing 22 and a driven gear 26 are provided around the end and fixed by a fixture 12b. Further, a detent member 26 a is provided between the rod member 12 and the driven gear 26.

  Reference numeral 21 denotes a support member that supports the rod 12 rotatably and is fixed to the base 40. The support member 21 is provided with a bearing accommodating portion 21 a that accommodates the thrust bearing 22 and a gear accommodating portion 21 e that accommodates the drive gear 25 and the driven gear 26. A flange portion 21b is provided at the lower end of the bearing housing portion 21a, and an outer peripheral block of the thrust bearing 22 is fixed by a fixing member 21d. Further, the support member 21 is provided with an insertion hole 21c so that the reduction gear 24 installed on the upper surface of the support member 21 and the drive gear accommodated in the gear accommodating portion 21e can be connected.

  The rotational drive mechanism 20 can rotate the rod member 12 and the pressure receiving member 13 around a shaft at a predetermined rotational speed by the above configuration. Further, the rotation drive mechanism 20 can absorb the rotation of the rod member 12 by the thrust bearing 22 and fix the rod member 12 to the base 40, and can restrict the movement of the rod member 12 in the axial direction.

The seal rings 14 and 15 are preferably capable of withstanding not only linear motion in the axial direction but also rotational motion about the shaft. Further, since ports for supplying the pressure medium are provided at both ends of the cylinder body 11, it is preferable that the rotation drive mechanism 20 is provided on the rod member 12 side as in the illustrated embodiment.
The cylinder device 10 may be provided with the cylinder body 11 fixed to the base 40 and the end of the rod member 12 fixed to the moving body 30.

FIG. 4 is a block diagram showing an embodiment of a machine tool provided with the cylinder device according to the present invention.
When the cylinder device 10 is used as a balancer for a vertical drive shaft of a machine tool, the cylinder device 10 always supplies a fluid having a constant pressure to one cylinder chamber so as to cancel the weight of the vertical moving body 30. Can function. Further, since the thrust bearing 22 receives only a force in one direction (only in the compression direction), the function can be satisfied with a simple structure.

  In the illustrated embodiment, the machine tool is provided with an XY table 41 on the base 40 side, and a vertical moving body 30 is provided on a fixed portion 50 above the base 40.

  The fixed portion 50 includes a pair of linear guides 35, 35, a ball screw 32 rotatably supported by bearings 32a, 32a, and a motor 34. The vertical moving body 30 includes slide blocks 36 and 36 that slide along the linear guides 35 and 35, a nut 33 that moves up and down by the rotation of the ball screw 32, and a main shaft 31. The vertical moving body 30 moves in the vertical direction along the linear guides 35 and 35 by rotating the ball screw 32 by the motor 34.

  In the illustrated embodiment, in the cylinder device 10, the cylinder body 11 is fixed to the up-and-down moving body 30, and the end of the rod member 12 is fixed to the base 40 via the rotation drive mechanism 20. The cylinder device 10 functions to supply a constant pressure fluid to the head side cylinder chamber 16 and cancel the weight of the vertically moving body 30 so as to reduce the load applied to the ball screw 34. .

  As described in the first embodiment, the rotational drive mechanism 20 is configured to constantly reduce the sliding resistance of the seal rings 14 and 15 by rotating the rod member 12 at a predetermined rotational speed. The rotation drive mechanism 20 is not limited to the configuration of the embodiment, and other configurations that can rotate the rod member 12 at a predetermined number of rotations can also be used.

  In the machine tool, when the moving direction of the vertical moving body 30 and the XY table 41 is reversed, the response is delayed and stick-slip occurs. In particular, the vertical moving body 30 caused stick slip several times that of the XY table 41 due to the sliding resistance of the seal rings 14 and 15 provided in the cylinder device 10. Table 1 shows the stick-slip amount of the vertically moving body 30 measured by changing the rotation speed of the rod member 12.

  The stick-slip amount was measured by operating the machine tool so as to draw an arc on the YZ plane (Z axis is the vertical direction) and measuring the amount of deviation between the control target value and the actual movement. Table 1 shows the amount of stick-slip when the vertical movement direction is reversed for each feed speed.

  The amount of stick-slip in the vertical direction is greatest when the rotation of the rod member 12 is stopped, decreases as the rotational speed is increased, and hardly changes at 20 rpm or higher. Since the stick slip amount when the rod member 12 is rotated at 20 rpm or more is substantially the same as the stick slip amount in the Y-axis direction, a large amount of stick slip caused by the cylinder device 10 is caused by rotating at 20 rpm or more. I was able to reduce the part.

FIG. 3 is a block diagram showing another embodiment of the cylinder device according to the present invention.
The cylinder body 11 has a groove formed on the sliding surface with the rod member 12 along the inner periphery. A seal ring 15 that contacts the outer peripheral surface of the rod member 12 is provided in the groove portion to prevent leakage of the pressure medium in the cylinder chamber. The pressure receiving member 13 is a cylindrical body having a diameter larger than that of the rod member 12 and smaller than the inner diameter of the cylinder body 11, and a gap is provided between the cylinder body 11 and the side surface of the pressure receiving member 12.

  The cylinder body 11 is filled with high-pressure gas, and can function to cancel the weight of the vertically moving body 30 by the pressure receiving member 12. Other configurations are the same as those of the first embodiment.

  Since the cylinder body 11 does not require a port for supplying a pressure medium, the rotation drive mechanism 20 can be provided on the cylinder body 11 side.

DESCRIPTION OF SYMBOLS 10 Cylinder apparatus 11 Cylinder main body 12 Rod member 13 Pressure receiving member 14, 15 Seal ring 16 Head side cylinder chamber 17 Rod side cylinder chamber 20 Rotation drive mechanism 21 Support member 22 Thrust bearing 23 Motor 24 Reduction gear 25 Drive gear 26 Drive gear 30 Movement Body 31 Main shaft 32 Ball screw 33 Nut 34 Motor 35 Linear guide 36 Slide block 40 Base 41 XY table 50 Fixed part

Claims (5)

Used as a balancer for vertical drive shafts of machine tools,
A cylindrical cylinder body filled with high-pressure gas and closed at both ends;
A rod member having one end positioned in the cylinder body and the other end protruding outward from an end surface of the cylinder body;
A pressure receiving member provided at one end of the rod member and capable of reciprocating along the axial direction in the cylinder body ;
A lubricating oil supplied to a contact portion between the cylinder body and the pressure receiving member or / and the rod member, and a cylinder device used for a machine tool ,
Independent of reciprocation along the axial direction of the rod member and the pressure receiving member with respect to the cylinder body, a rotation drive mechanism is provided for rotating the rod member and the pressure receiving member relative to the cylinder body. Cylinder device used for machine tools . Between the sides of the rod member and the cylinder body, and said cylinder body and Ri Oh provided a seal ring between the side surface of the pressure receiving member, according to claim 1, high-pressure gas is sealed in one of the cylinder chamber Cylinder device.   The cylinder device according to claim 1, wherein a seal ring is provided between the cylinder body and the side surface of the rod member, and a gap is provided between the cylinder body and the side surface of the pressure receiving member.   The cylinder device according to any one of claims 1 to 3, wherein the rotational drive mechanism includes a thrust bearing that restricts movement in an axial direction.   A machine tool including a moving body that moves in a vertical direction by a driving unit, the machine tool including the cylinder device according to any one of claims 1 to 4.

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