JPH02225805A - Deceleration method for hydraulic actuator - Google Patents

Abstract

PURPOSE:To enable smooth deceleration by braking a moving body while operating a piston cylinder member by means of pressure of water hammer phenomenon generated upon changeover of a hydraulic circuit at the time of deceleration, and reducing shock. CONSTITUTION:Return oil from a hydraulic motor 5 is separately sent to pipe passages 12, 13 which are branched from a pipe passage 11, through a solenoid valve 7. The oil is then introduced to high and low speed throttle valves 14, 15. Only at the time of high speed operation, the oil is returned from a pipe passage 16 through a two position solenoid changeover valve 17 and a pipe passage 18 to a storage tank 10. A hydraulic cylinder 20 energized in a drawing direction is fixed to a bite holder, a brake pad 2 is installed on a piston rod end, and braking is performed on an inner peripheral surface of a turret upon reception of water hammer pressure generated on the pipe passage 16. It is therefore possible to optimally distribute braking force and back pressure effect, smooth the deceleration in order to reduce shock, soften the pressure of a driving system and reduce cost.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a method for decelerating a hydraulic actuator during interlock drive.

2. Description of the Related Art For example, in a tool rest having a turning mechanism using a hydraulic motor 101 as shown in FIG.
In order to stop the machine at the indexed position, a deceleration mechanism is required to reduce the speed before the target indexed position. Conventionally, this speed reduction mechanism has a high-speed throttle 103 and a low-speed throttle 104 arranged in parallel on the return bias of the hydraulic circuit, and a large flow rate flows through both throttles 103 and 104 at high speeds by switching a solenoid valve 105. , at low speed, low speed aperture 1
A back pressure throttling scheme is commonly used which allows a small flow to flow through the circuit through only the 04.

Problems to be Solved by the Invention In the back pressure throttling system described in the prior art section, when the solenoid valve 105 is switched during deceleration, the flow of oil through the throttle 103 with a relatively large flow rate is abruptly interrupted. Kinetic energy is replaced by pressure energy, and high pressure is generated in the circuit behind the solenoid valve 105, causing a water hammer phenomenon in which this is transmitted upstream. This high pressure becomes a back pressure on the hydraulic motor 101, causing a large sickle to suddenly stop the hydraulic motor, making it impossible to obtain a smooth deceleration operation, and also preventing the inertia of the turret from being received by the drive gears 106 and 107. Therefore, there is a problem in that the gear must have a large strength.

The present invention was made in view of the above-mentioned problems of the conventional technology, and its purpose is to alleviate the pressure of the water hammer phenomenon and apply a brake to the interlocking body to absorb the inertial force. The purpose is to provide a method that can reduce shock and reduce the load on the drive gear to smoothly perform deceleration.

! ! Means for Solving the Problem In order to achieve the above object, the method of decelerating a hydraulic actuator in the present invention reduces the amount of water generated by switching the hydraulic circuit during deceleration when decelerating a hydraulic actuator using a back pressure throttling method. The piston-cylinder member is actuated by the pressure of the impact phenomenon to apply a brake to the interlocking body.

When the electromagnetic switching valve is switched to reduce the action and one of the circuits forming the back pressure throttle circuit with a high flow rate is closed,! High pressure is generated in the circuit behind the magnetic switching valve, causing a water hammer phenomenon that becomes a pressure wave that propagates upstream. The pressure from this water hammer phenomenon is then transmitted to the cylinder, causing the piston to move and apply a brake to the interlocking body.

The water hammer pressure loses some of its energy to actuate the piston and also acts as back pressure on the hydraulic actuator, causing it to stop.

Example An embodiment will be described with reference to FIG.

A turret 2 is fixed to the tip of a rotating shaft l that is rotatably provided on the tool rest of the NC lathe, and a gear 5 fitted to the output shaft of a hydraulic motor 4 fixed to the tool rest is connected to the rotating shaft l. It is meshed with the gear 3 that is fitted into the. In the circuit for supplying pressure oil to the hydraulic motor 4, the source pressure P supplied from the pump is sent to the 3-position group valve 7 through the pipe line 6, and the 74
It is switched by a magnetic switching valve 7, and is supplied to the hydraulic motor 4 through either one of the pipes 8 and 9. Also, the circuit for the oil returned from the hydraulic motor 4 is connected to a pipe line 8.
, 9 to the solenoid valve 7, and the conduit 11
It is divided into conduits 12, 1.3 that branch through it, and is sent to a high-speed throttle 14 and a low-speed throttle 15. and aperture 1
4, the oil is restricted to a predetermined flow rate through pipe ai16 to position 2! It is sent to the magnetic switching valve I7, and returned to the storage tank 10 via the pipe 18 only at high speeds by switching the electromagnetic switching valve. Further, the oil which has been throttled down to a predetermined flow rate by the throttle 15 is always returned to the storage tank IO through the pipe line +8.

Furthermore, a hydraulic cylinder 20 is fixed to the tool rest in a direction perpendicular to the rotation axis 1, and the piston loft integrated with the piston is always urged to retract by a spring 21, and the inner circumference of the large diameter part of the turret is attached to the tip of the piston loft. A brake butt 22 is attached facing the surface. Pressure oil is supplied to the hydraulic cylinder 20 through a pipe line 23 that branches from the middle of the pipe line 16, and the pipe line 16 is communicated with the pipe line 18 while the hydraulic motor 4 is rotating at high speed. Therefore, low pressure is supplied. And solenoid switching valve 17 for deceleration
When is switched to position ■, the space between pipes 16 and 18 is suddenly closed, the flow of oil is abruptly interrupted, and the kinetic energy of the oil whose flow is blocked changes into pressure energy. A high pressure (water hammer pressure) is generated in the pipe line 16 and is transmitted to the hydraulic cylinder 20 via the pipe line 23 as a pressure wave. The spring force of the spring 21 provided in the hydraulic cylinder 20 is set to a range where the spring 21 is deflected by this water hammer pressure and is not deflected by the low hydraulic pressure during high speed rotation, and the brake butt 22 is bent by the water hammer pressure. It is pressed against the surface and applies a brake. The water hammer pressure, which lost some energy to apply the brakes, is transferred to the hydraulic motor 4.
The spring force of the spring 21 is set so that the brake force and this back pressure are equal to m, and the force of the spring 21 is set so that the brake force and this back pressure are equal to m. Whether it will bend or not due to relatively strong hydraulic pressure is out of the question. Furthermore, a detector 26 is attached to the tool post to detect the rotational position of the turret, and a gear 25 fitted to the detector is meshed with a gear 24 fitted to the rear end of the pivot shaft.

Next, the operation of this embodiment will be explained. Now under NC orders! The magnetic switching valve 7 is switched to the ■ position, and the electromagnetic switching valve 17 is switched to the V position, and the source pressure P supplied from the pump is transferred to the pipe line 6.
, 9 to the hydraulic motor 4, and return oil from the motor 4 is supplied to the hydraulic motor 4 via the pipe 8. The flow rate is limited by a high-speed throttle 14 and a low-speed throttle 15 arranged in parallel via 11.12.13, and is returned to the storage tank lO via line 16.18. A large amount of oil flows, the hydraulic motor 4 is rotated, and the turret 2 is rotated via the gears 3 and 5. At this point, the pressure inside the pipe line 16 is low, so the force of the spring 21 is strong, and the brake butt 22 is not in contact with the inner peripheral surface of the turret.The detector 26 indicates that the turret 2 is approaching the indexed position. When this is detected, the electromagnetic switching valve I7 is switched to position (3) in response to a NO command, and the pipe lines 16 and 18 are cut off, so that only the flow rate passes through the low-speed throttle 15. This flow rate is very small compared to the flow rate at high speeds, and as the oil flowing through the pipe line 16 is abruptly cut off, a high water hammer pressure is generated within the pipe line 16. This water hammer pressure is transmitted to the hydraulic cylinder 20 through the pipe line 23, and the piston rod moves against the force of the spring 21, causing the brake pad 22 at the tip to move against the turret 20.
It is pressed against the inner peripheral surface, and when the brake is applied, the inertial force is absorbed and the turret is decelerated. The water hammer pressure, which has lost a part of its energy to move this piston rod, uses a further part of it to move the piston 13. Aperture 15. It is released into the atmosphere through the pipe 18 and is lost, but the rest is lost in the pipe 11 and the solenoid valve 7. Conduit 8
The pressure is transmitted to the hydraulic motor 4 as back pressure, and the hydraulic motor 4 is decelerated.

When the pressure wave caused by this water hammer phenomenon subsides, the flow rate is reduced to a small amount through the throttle 15, and the hydraulic motor 4 rotates at a low speed. Then, when turret 2 rotates to the desired indexing position,
The detector 26 detects that the index position has been reached, and the NC
In response to the command, the electromagnetic switching valve 7 is switched to the ■ position, the supply of pressure oil is stopped, and at the same time, the pipe line 8.9 is communicated with the return circuit, the hydraulic motor 4 is stopped, and the turret 2 is closed by a clamp mechanism (not shown). is clamped and indexing is completed.

Note that the deceleration method of the present invention is not limited to being used only for the turret rotation mechanism using the hydraulic motor of this embodiment, but is also applicable to chain drive mechanisms such as automatic tool changers and tool magazine devices of machining centers, or hydraulic It goes without saying that the present invention can be applied to all types of back pressure throttling type deceleration, such as linear drive mechanisms using cylinders.

Effects of the Invention Since the present invention is configured as described above, it produces the following effects. The back pressure throttling type deceleration mechanism uses a hydraulic cylinder activated by water hammer pressure to apply the brakes to the interlocking body, optimally distributing the braking force and back pressure effect, resulting in smooth deceleration. Since the shock is reduced, there is no need to increase the strength of the drive system, and costs can be reduced.

[Brief explanation of the drawing]

FIG. 1 is a circuit diagram of the hydraulic actuator deceleration method of the present invention, and FIG. 2 is a circuit diagram of a conventional technique. 2...Turret 5...Hydraulic motor 20...Hydraulic cylinder 22...Brake pad fs1 diagram fH2 diagram

Claims (1)

[Claims] (1) When decelerating the hydraulic actuator (4) using the back pressure throttling method, the piston cylinder member (20) is actuated by the pressure of the water hammer phenomenon generated by switching the hydraulic circuit during deceleration, and the interlocking body (2) A hydraulic actuator deceleration method characterized by applying a brake.