JPH0526358A - Pressure oil supplying and draining device - Google Patents

Abstract

PURPOSE:To prevent a hydraulic operating member, which is doubly sealed by two check valves, from lowering the pressure by wrong operation of a device which supplies pressure oil to the hydraulic chamber of a hydraulic cylinder and drains the oil from the chamber. CONSTITUTION:The operating port A of a check valve 6 furnished with a valve opening function is connected to a hydraulic operating chamber 4a, the pressure port P of the check valve 6 is concurrently connected to a quick disconnect coupling 8 with both side check valves by means of pumping path 7, and a pressure lowering means 13 is provided for the pumping path 7. In this case, the pressure lowering means 13 is made up of a cylinder port 17 connected to the pumping path 7, a piston 18 which is inserted in the cylinder port 17 in an oil tight condition in such a way as to be freely moved ahead and afterward, and an expansion chamber E arranged at one end side of the piston 18 so as to be communicated with the pumping path 7, and of a presser fixture 19 which operationally advances the piston 18 into the expansion chamber E.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to, for example, a hydraulic clamp device for fixing a workpiece to be machined in a machining center to a work pallet, which device supplies and discharges pressure oil to and from a hydraulic working chamber of a hydraulic cylinder. Regarding

[0002]

2. Description of the Related Art In this type of pressure oil supply / discharge device, conventionally,
There is one described in Japanese Utility Model Publication No. 63-34824 previously proposed by the present inventor. This is to connect the working port of the check valve with a valve opening function to the hydraulic working chamber of the hydraulic clamp provided on the work pallet, and to connect the pressure port of the check valve to a quick joint with check valves on both sides by the supply / discharge passage. The pressure reducing means is provided in the supply / discharge path. The pressure reducing means is composed of a pressure-release on-off valve composed of a metal-touch steel ball and a valve seat.

At the time of clamping, the on-off valve is closed in advance, and in this state, the pressure oil from the hydraulic source is supplied to the hydraulic working chamber from the quick coupling through the check valve with the valve opening function. Then, the quick joint is separated and the work pallet is carried into the machining center. During this clamp, the hydraulic clamp is held in a clamped state by double sealing the hydraulic working chamber with two check valves, a check valve with a valve opening function and a check valve in the quick coupling. I am doing it.

On the other hand, at the time of unclamping, first, the on-off valve is opened to reduce the pressure in the supply / discharge passage to the atmospheric pressure. As a result, the operating force for connecting the quick coupling is small, and the connecting operation is facilitated. Next, the check valve with the valve opening function is opened by the forced valve opening means. Then, the pressure oil in the hydraulic working chamber of the hydraulic clamp is discharged to the oil tank through the work port, the pressure port, and the quick joint.

[0005]

The above-mentioned conventional techniques have the following problems. (a) If the pressure relief on-off valve is not completely closed due to an operator's operation error during the clamp operation in which the pressure in the hydraulic chamber drops due to an operation error, the check valve with the valve opening function When a slight leak occurs in the supply / discharge path, the pressure oil is discharged to the outside from the supply / discharge path via the on-off valve. As a result, the internal pressure of the hydraulic working chamber decreases, and the clamped state cannot be maintained.

(B) When the opening / closing valve is opened and operated during unclamping where oil stains occur, the pressure oil in the supply / discharge passage is expelled vigorously from the opening / closing valve, and the equipment room is contaminated with oil. Oil is exhausted. To solve this problem, it is conceivable to connect the discharge port of the on-off valve and the oil tank with a return pipe. However, in this case, the space for the return pipe is required and the production cost is increased, which is a new problem.

(C) Since the pressure lowering means consisting of the on-off valve, which is time-consuming to operate the pressure lowering means, is made of metal touch, the torque required for the valve closing operation is large and the operation is troublesome, and the operation is excessive. Since the steel balls and the valve seat are easily plastically deformed by the torque, minute leakage is likely to occur.

It is an object of the present invention to prevent a pressure drop in a hydraulic working chamber due to an operation error, to prevent oil contamination and to reduce manufacturing cost at the same time, and to easily operate a pressure drop means. .

[0009]

In order to achieve the above object, the present invention comprises a pressure reducing means 13, for example, as shown in FIGS.
As shown in FIG.

(Invention of Claim 1) The working port A of the check valve 6 with a valve opening function is connected to the hydraulic working chamber 4a, and the pressure port P of the check valve 6 is checked on both sides by the supply / discharge passage 7. It is connected to a quick joint 8 with a valve, and a pressure reducing means 13 is provided in the supply / discharge passage 7. A cylinder hole 17 in which the pressure reducing means 13 is connected to the supply / discharge passage 7 and the cylinder hole 1
7, the piston 18 fitted in an oil-tight manner, and the piston 1
The expansion chamber E is disposed at one end of the expansion chamber 8 and communicates with the supply / discharge passage 7, and a pressing tool 19 for advancing the piston 18 into the expansion chamber E.

(Invention of Claim 2) In the structure of Claim 1, the pressing member 19 is provided on the peripheral wall 61 of the cylinder hole 17.
The screw was fitted so that it could move back and forth.

(Invention of Claim 3) In the configuration of claim 1 or 2, the piston 18 and the pressing member 19 are formed of different members.

(Invention of Claim 4) In the structure of Claim 3, a stopper 64 for preventing the pressing member 19 from moving backward by a predetermined amount or more is provided on the peripheral wall 61 of the cylinder hole 17.

[0014]

The present invention operates as follows, for example, as shown in FIG. When the workpiece 3 is clamped, the piston 18 is advanced into the expansion chamber E by the pressing tool 19 to reduce the volume of the expansion chamber E prior to the clamping operation.

Next, with the check valve 6 switched to the supply position X, the pressure port P is passed from the hydraulic pressure source 11 through the quick coupling 8.
Supply pressure oil to. Then, the pressure oil is supplied from the check valve 6 to the hydraulic working chamber 4a via the work port A, and when the hydraulic pressure in the chamber 4a rises to the set pressure, the check valve 6 is turned on. To act. Subsequently, the quick joint 8 described above
Is separated and the check valve (not shown) in the second joint 8b and the check valve 6 doubly seal the hydraulic working chamber 4a to set the internal pressure of the chamber 4a. Keep it under pressure.

When the workpiece 3 is unclamped, the pressing tool 19 is retracted in a direction away from the expansion chamber E. Then, the piston 18 is retracted by the pressure in the supply / discharge passage 7, the volume of the expansion chamber E is increased, and the pressure in the supply / discharge passage 7 is rapidly reduced. As a result, the operating force for connecting the quick coupling 8 is small, and the connecting operation becomes easy.

[0017]

The present invention has the following effects because it is configured and operates as described above. (Invention of Claim 1) (a) Since the expansion chamber provided in the cylinder hole capable of preventing the pressure drop in the hydraulic working chamber due to an operation error is oil-tightly sealed by the piston, the forward / backward operation of the pressing tool is performed. Even if there is a mistake in the pressure oil, it is possible to prevent pressure oil from leaking out from the supply / discharge passage. Therefore, even if a slight leak occurs from the check valve with the valve opening function to the supply / discharge passage, it is possible to prevent the pressure drop in the hydraulic working chamber.

(B) Since the pressure oil in the supply / discharge passage capable of both preventing oil pollution and reducing the manufacturing cost is not discharged to the outside, the equipment room is not contaminated with oil and the oil is not consumed. Moreover, in order to obtain the above effects, unlike the conventional example, it is not necessary to provide an oil return pipe, so the piping space can be omitted and the pressure oil supply / discharge device can be manufactured at low cost.

(C) The pressure reducing means can be easily operated. The operation of the pressure reducing means is performed by moving the piston relatively to the cylinder hole, so that the sliding resistance of the piston sealing packing is increased. The operating force required to overcome the above is much smaller than the closing force of the conventional metal touch type on-off valve. Therefore, the operation of the pressure reducing means becomes easy. Moreover, unlike the metal touch type of the conventional structure, the sealing surface is not damaged by an excessive operating force, so that minute leakage can be reliably prevented.

(Invention of Claim 2) Since the pressing tool is screw-fitted to the peripheral wall of the cylinder hole, the structure for moving the pressing tool forward and backward relative to the cylinder hole can be simply made. For this reason, the pressure oil supply / drainage device can be made small and simple, and there are few failures.

(Invention of Claim 3) By constituting the piston and the pressing tool by separate members, it is possible to prevent the piston from rotating around the axis when the pressing tool is moved forward and backward. As a result, the piston sealing packing is less worn and has a longer life.

(Invention of Claim 4) When the pushing tool is moved backward, the stopper serves as a guide for the amount of backward movement, so that the operation of the pressure reducing means is further facilitated and the pushing tool falls off from the peripheral wall of the cylinder hole. Can be prevented.

[0023]

Embodiments of the present invention will be described below with reference to the drawings. (First Embodiment) FIGS. 1 and 2 show a first embodiment. The circuit diagram of FIG. 1 shows a hydraulic clamp device to which the present invention is applied. This apparatus presses and fixes a work piece 3 on a fixed frame 2 of a work pallet 1 carried into a machining center by a clamp tool 5 of a hydraulic clamp 4. The hydraulic clamp 4 is composed of a single-action spring return type hydraulic cylinder. The hydraulic operating chamber 4a is connected to the switching valve 9 through the working port A and the pressure port P of the check valve 6 with the valve opening function, the supply / discharge passage 7, and the quick joint 8 with the double-sided check valve. The switching valve 9 is arranged outside the work pallet 1.

When clamping the work piece 3, the first joint 8a of the quick joint 8 is connected to the second joint 8b, the check valve 6 is switched to the supply position X by the forced valve opening means 6a, and the switching valve 9 is opened. Switch to supply position M. Then, the pressure oil from the hydraulic pressure source 11 is supplied to the working chamber 4a through the switching valve 9, the quick coupling 8 and the check valve 6 in this order, and the clamp 5 presses and fixes the workpiece 3.

In this clamped state, the quick joint 8 is separated, the work pallet 1 is carried into the machining center, and then the work piece 3 is processed. After the machining of the workpiece 3, the work pallet 1 is first carried out from the machining center, and then the clamped state of the machined workpiece 3 is released.

At the time of unclamping the processed workpiece 3, first, the pressure oil in the supply / discharge passage 7 is reduced by the pressure reducing means 13.
And then the quick coupling 8 is connected. Subsequently, the check valve 6 is switched to the discharge position Y, and
The switching valve 9 is switched to the discharge position N. Then, the working chamber 4a
The pressure oil of the check valve 6
It is returned to the oil tank 15 through the route of the quick coupling 8 and the switching valve 9. As a result, the processed workpiece 3 is released from the clamped state and can be taken out of the work pallet 1.

When a new workpiece 3 is clamped, the check valve 6 is switched to the supply position X and the switching valve 9 is switched to the supply position M to supply pressure oil to the hydraulic clamp 4 as described above. is there.

The pressure reducing means 13 includes a cylinder hole 17 branched from the supply / discharge passage 7 and the cylinder hole 1 thereof.
7, a piston 18 that can move back and forth freely and is inserted in an oil-tight manner,
An expansion chamber E provided at one end of the piston 18 and a pressing tool 19 for advancing the piston 18 into the expansion chamber E. The specific structures of the check valve 6 and the pressure reducing means 13 will be described below with reference to FIG.

First, the check valve 6 will be described. A check valve chamber 22 is formed in the right side portion of the valve case 21, and the check valve chamber 22 is connected by the supply / discharge passage 7 to the quick coupling 8 described above.
Be communicated to. That is, the pressure supply hole 23 is opened on the left end surface side of the check valve chamber 22, and the pressure supply hole 23 is formed in the pressure port P.
And the communication passage 24 in order, and is communicated with the inlet nozzle 25. The rapid joint 8 is attached to the inlet nozzle 25. Further, the inlet filter 26 is mounted in the right end portion of the inlet nozzle 25. An outlet hole 28 is opened in the upper peripheral surface of the check valve chamber 22, and the outlet hole 28 communicates with the working port A via an outlet filter 29. Further, the check valve body 32 inserted in the check valve chamber 22 is elastically closed by the check spring 34 to the check valve seat 33 formed on the peripheral wall of the pressure supply hole 23.

The forced valve opening means 6a is constructed as follows. A rod insertion hole 36 is formed in series with the check valve chamber 22 and the pressure supply hole 23. A valve opening operation rod 37 is inserted into the insertion hole 36 through a packing 38 so as to be slidable in the left-right direction in an oil-tight manner. The right end of the rod 37 faces the check valve body 32, and the left end of the rod 37 faces the cam groove 41 of the shaft 40. The shaft 40 has a support hole 4 which is formed by penetrating the valve case 21 in a lateral direction.
2 is rotatably supported, and is configured to rotate along with an operation lever 43 fixed to one end of the shaft.

The operating lever 43 has a valve opening operation posture D (see the one-dot chain line diagram) for switching the rod 37 to the valve opening position on the right side by the shaft 40, and the rod 37 has the pressure supplying hole 23.
It is possible to switch to the valve opening release posture C (see the solid line diagram) that allows switching from the valve opening position to the left valve opening release position by the hydraulic pressure inside. A valve open state holding means 45 for holding the rod 37 at the valve open position on the right side is provided. This means 45 is configured such that a steel ball 47 inserted into the peripheral wall of the insertion hole 36 can be engaged with a groove 46 formed in the left portion of the rod 37 by a spring 48.

The groove 5 formed in the lower portion of the shaft 40
At 0, the elastic force of the lever return spring 51 acts counterclockwise. Reference numeral 52 is a pressing cylinder that contacts the groove 50, and reference numeral 53 is a spring force adjusting bolt. The return spring 51 allows the lever 43 to switch from the valve opening release posture C to the valve opening operation posture D, and at the same time, the lever 43 automatically returns from the valve opening posture D to the valve opening release posture C. The elastic pressure is set to.

The pressure reducing means 13 is constructed as follows. The cylinder hole 17 is opened upward in the upper left portion of the valve case 21. The piston 18 is inserted into the cylinder hole 17 through a packing 56 so as to be vertically oil-tightly movable. The expansion chamber E formed on the lower side of the piston 18 is communicated with the supply / discharge passage 7 by the communication hole 57.

A cylindrical bolt 62 is screwed and fixed to an upper portion of the peripheral wall 61 of the cylinder hole 17, and the pressing tool 19 is screwed to the bolt 62 so as to be movable back and forth in the vertical direction. In addition, the wrench hole 6 formed in the upper portion of the bolt 62.
A stopper 64 for preventing upward movement of the pressing tool 19 by a predetermined amount or more is provided on the peripheral wall of No. 3.

The check valve 6 and the pressure reducing means 13 described above.
Operates as follows, as shown in FIGS. When the workpiece 3 is clamped, as shown in FIG. 2, the operation lever 43 is switched to the lower valve-opening release position C, and the valve-opening operation rod 37 is switched to the left valve-opening release position. First, prior to the clamp operation, the piston 18 is advanced downward by the pressing tool 19,
The volume of the expansion chamber E is reduced.

Then, as indicated by the solid arrow in FIG.
When pressure oil is supplied from the quick coupling 8 to the inlet nozzle 25, the pressure oil flows into the pressure supply hole 23 through the pressure port P, and the check valve body 32 is separated from the check valve seat 33 to reverse. It is supplied to the working port A from the stop valve chamber 22 through the outlet hole 28. As a result, the cylinder of the hydraulic clamp 4 (see FIG. 1) extends. Hydraulic working chamber 4a and check valve chamber 2
When the hydraulic pressure in 2 rises to the set pressure, the check valve body 32 closes and contacts the check valve seat 33 by the elastic force of the check spring 34, and performs the check function. Subsequently, the quick joint 8 is separated, and the working chamber 4a is doubly sealed by the check valve (not shown) in the second joint 8b and the check valve 6. The work pallet 1 is carried into the machining center.

When unclamping the work piece 3 after finishing the work piece 3, the pressing tool 19 is first retracted upward. Then, the piston 18 retreats upward due to the oil pressure in the supply / discharge passage 7, the volume of the expansion chamber E increases, and the pressure in the supply / discharge passage 7 decreases to almost atmospheric pressure. At this time, the operating torque of the pressing tool 19 is suddenly reduced, so that the operator can feel the pressure reduction of the supply / discharge path 7 by touch. Subsequently, the first joint 8a is connected to the second joint 8b of the quick joint 8 under the above-mentioned depressurized state.

By the way, if it is forgotten to advance the pushing tool 19 before starting the clamping operation, first push the pushing tool 19 downward from the upper retracted position before the unclamping operation. Manipulate. Then, the piston 18 advances into the expansion chamber E to increase the pressure in the supply / discharge passage 7 and open the check valve body 32. This allows
The pressure oil in the expansion chamber E is pushed out from the check valve chamber 22 through the work port A into the hydraulic pressure working chamber 4a. After that, when the pressing tool 19 is retracted upward, the pressure in the supply / discharge passage 7 is reduced to the atmospheric pressure in the same manner as described above.

Further, during the above-mentioned clamping, when oil is leaking from the sealing portion of the check valve body 32 and the check valve seat 33 to the supply / discharge passage 7, the pressing tool 19 is retracted upward. Even if the pressure in the supply / discharge passage 7 does not decrease, it can be determined that the check function of the check valve 6 is impaired.

In the use state of the apparatus of this embodiment,
Between the check valve in the second joint 8b and the check valve 6, the stored oil amount was calculated to be about 7.0 cm ^3, and the packing 38
And the amount of elastic deformation of multiple gaskets is about 0.10 cm
Calculated as ³ .

Therefore, the compression amount or expansion amount ΔV of oil is represented by the stored oil amount × compression ratio × use pressure, and ΔV = 7.0c
m ³ × 6.5 · 10 ⁻⁵ cm ² / kgf × 250 kgf / cm ² = 0.11 cm ³ . As a result, necessary volume R of the expansion chamber E which is required of the pressure is the reservoir oil from working pressure (250kgf / cm ²⁾ to reduce to the atmosphere ^{pressure, R = 0.10cm 3 + 0.11cm 3} = 0.21 cm ^3, and the need in a small volume.

After the supply / discharge passage 7 is depressurized and the quick joint 8 is connected as described above, the operation lever 43 is switched to the upper valve opening operation posture D. Then, the rod 37 is switched to the valve opening position on the right side by the cam groove 41 of the shaft 40, and the check valve body 32 resists the internal pressure of the check valve chamber 22 and the check valve seat 33.
Is forcibly separated from. As a result, the pressure oil in the working chamber 4a flows from the work port A to the outlet hole 28, the check valve chamber 22, the pressure supply hole 23, the pressure port P, and the inlet nozzle 25 as shown by the one-dot chain line arrow in FIG. The oil pressure in the working port A is rapidly reduced by being discharged from the quick coupling 8 in sequence.
In this state, the steel ball 47 engages with the groove 46 of the rod 37 and holds the rod 37 at the valve opening position on the right side.

Therefore, even if the worker releases his / her hand from the operation lever 43 and the lever 43 returns to the lower valve-opening release posture C by the elastic force of the return spring 51, the check valve body 32 is moved by the rod 37. The valve is kept open to allow the pressure oil in the working chamber 4a to be continuously discharged.

When a new work piece 3 is clamped, pressure oil is supplied from the quick joint 8 to the pressure supply hole 23 while the rod 37 is held at the right valve open position by the valve open state holding means 45. To do. Then, the hydraulic pressure pushes the rod 37 to the left against the engagement resistance of the valve-opening state holding means 45 and the sliding resistance of the packing 38, and automatically returns to the valve-opening release position. As a result, the check valve body 32 is switched to the check state.

The first embodiment described above can be modified as follows. The pressing tool 19 has a cylindrical bolt 62.
Instead of supporting the valve case 21, the valve case 21 may be directly screw-fitted. The pressing tool 19 may be moved forward / backward by a cam mechanism or a solenoid instead of being moved forward / backward by screw fitting. The hydraulic clamp 4 may be a double-acting hydraulic cylinder or a balance-type clamp tool.

3 to 6 show another embodiment of the pressure reducing means 13, respectively. In these examples,
In principle, the same members as those in the first embodiment are designated by the same reference numerals.

(Second Embodiment) As shown in FIG. 3, a piston rod 71 is projected upward from a piston 18 and a pressing tool 19 is opposed to the piston rod 71. The stopper 64 shown in FIG. 2 is omitted from the tubular bolt 62.

(Third Embodiment) As shown in FIG. 4, a piston 18 and a pressing tool 19 are integrally formed, and the pressing tool 19 is formed.
The upper part of is screwed into the cylindrical bolt 62.

(Fourth Embodiment) As shown in FIG. 5, a cylinder hole 17 is opened on the left end surface of the valve case 21, and a piston 18 is provided on the right side of the inlet nozzle 25. It is fitted with a screw so that it can move back and forth in the left-right direction. The pressing tool 19 is an inlet nozzle 25.
And a screw fitting portion 75. The taper male screw on the left side of the inlet nozzle 25 has a second quick joint.
The joint 8b is fixed. When the pressure in the supply / discharge passage 7 is reduced, the inlet nozzle 25 is rotated toward the loosening side with respect to the peripheral wall 61 of the cylinder hole 17, as shown in the chain double-dashed line diagram,
The volume of the expansion chamber E formed on the right side of the piston 18 is increased.

(Fifth Embodiment) As shown in FIG. 6, a cylinder hole 17 is opened in the right end surface of the second joint 8b of the quick joint, and a piston 18 is provided in the left portion of the inlet nozzle 25. . The pressing tool 19 includes a peripheral wall 61 of the cylinder hole 17.
And a screw fitting portion 79. When the pressure in the supply / discharge passage 7 is decreased, as shown in the chain double-dashed line diagram, the volume of the expansion chamber E formed on the left side of the piston 18 is rotated by rotating the second joint 8b to the loose side with respect to the inlet nozzle 25. To increase.

[Brief description of drawings]

FIG. 1 is a circuit diagram of a hydraulic clamp device according to a first embodiment.

FIG. 2 is a vertical cross-sectional view of a check valve and pressure reducing means used in the above device.

FIG. 3 is a vertical cross-sectional view of pressure reducing means according to the second embodiment.

FIG. 4 is a vertical cross-sectional view of the pressure reducing means of the above, showing a third embodiment.

FIG. 5 is a vertical cross-sectional view of the pressure reducing means of the above, showing a fourth embodiment.

FIG. 6 is a vertical cross-sectional view of the pressure reducing means of the same as the fifth embodiment.

[Explanation of symbols]

4a ... hydraulic working chamber, 6 ... check valve with valve opening function, 7 ... supply / discharge passage, 8 ... quick joint, 13 ... pressure reducing means, 17 ... cylinder hole, 18 ... piston, 19 ... pressing tool, 61 ... cylinder Peripheral wall of hole 17, 64 ... Stopper, A ... Work port, P
… Pressure port, E… Expansion chamber.

Claims (4)

[Claims] 1. A check valve with a valve opening function in a hydraulic working chamber (4a)
Connect the work port (A) of (6) and check the valve
The pressure port (P) of (6) is connected to the quick joint (8) with check valves on both sides by the supply / discharge passage (7), and the pressure reducing means (13) is provided in the supply / discharge passage (7). In a pressure oil supply / discharge device, a cylinder hole (17) connecting the pressure reducing means (13) to the supply / discharge passage (7) and a piston fitted in the cylinder hole (17) in an oil-tight manner. (18), an expansion chamber (E) arranged at one end of the piston (18) and communicating with the supply / discharge passage (7), and the piston (18) is advanced into the expansion chamber (E). A pressure oil supply / drainage device comprising a pressing tool (19) to be operated. 2. The pressure oil supply / discharge device according to claim 1, wherein the pressing tool (19) is screwed into the peripheral wall (61) of the cylinder hole (17) so as to be movable back and forth. 3. The pressure oil supply / discharge device according to claim 1, wherein the piston (18) and the pressing tool (19) are formed of different members. 4. The pressure oil supply / drainage device according to claim 3, wherein a stopper (64) for preventing the pressing tool (19) from moving backward by more than a predetermined amount is provided on the peripheral wall (61) of the cylinder hole (17). The one provided.