JPH1047310A - Fluid pressure cylinder device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To make a fluid pressure cylinder device maintenance-free over a long period, by preventing a liquid of water soluble cutting oil, water, etc., in the atmosphere from infiltrating in a cylinder hole. SOLUTION: In a lower side of a piston 10 inserted to a cylinder hole 9 of a housing 7, a spring chamber 11 is formed. This spring chamber 11 is made to communicate with an atmospheric side by a pressure bleeding first passage 21 and a high vacuum preventing second passage 22. A first check member 36 provided in the first passage 21, for instance when an internal pressure of the spring chamber 11 rises to 0.7kgf/cm<2> or more, is separated from a first check valve seat 34 against a first check spring 37. A second check member 46 provided in the second passage 22, when an internal pressure of the spring chamber 11 is lowered down to a medium vacuum condition, for instance, about -0.25kgf/cm<2> , is separated from a second check valve seat 44 against a second check spring 47.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a hydraulic cylinder device.

[0002]

2. Description of the Related Art Generally, in a fluid pressure cylinder device, a piston is inserted into a cylinder hole of a housing, and a first chamber formed at one end of the piston communicates with a space outside the housing through a breathing passage. The pressure fluid is supplied to and discharged from the second chamber formed on the other end side.

When a pressure fluid is supplied to the second chamber, the piston contracts the first chamber to increase the internal pressure of the first chamber, so that the air in the first chamber passes through the breathing passage. It flows out of the housing. Conversely, when the pressurized fluid is discharged from the second chamber, the piston expands the first chamber by the urging force of the spring.
The internal pressure of the chamber becomes lower than the atmospheric pressure, and the atmosphere outside the housing flows into the first chamber through the above-mentioned breathing passage.

Conventionally, a wire mesh filter or a sintered metal filter has been mounted in the middle of the above-mentioned respiratory tract. Thus, when the atmosphere outside the housing passes through the breathing path, foreign matter such as dust and cuttings in the atmosphere is captured by the filter, and the foreign matter can be prevented from entering the housing.

[0005]

By the way, the above-mentioned filter can capture solid foreign matter such as dust and swarf,
Cannot capture liquids and gases. Therefore, the following problem occurs when the fluid pressure cylinder device is used in an atmosphere containing corrosive liquids and gases. For example, N using water-soluble cutting oil
When the above-mentioned fluid pressure cylinder device is used for the work clamp of the C lathe, a large amount of water-soluble cutting oil is scattered around the cylinder device, and the atmosphere contains a large amount of mist-like water droplets. It is.

[0006] When the atmosphere outside the housing flows into the housing through the breathing hole, the water-soluble cutting oil or the mist drops easily pass through the filter and enter the housing. The penetrated water-soluble cutting oil and water droplets deteriorate and deteriorate in the housing and corrode the sliding surface of the cylinder hole and the sliding surface of the piston, so that the piston cannot slide smoothly. As a result, the hydraulic cylinder device cannot be used for a short period of time. An object of the present invention is to make it possible to use a fluid pressure cylinder device favorably for a long period of time even in an atmosphere containing corrosive liquids and gases.

[0007]

[Means for Solving the Problems]

(Invention of claim 1) To achieve the above object, claim 1
In the present invention, for example, as shown in FIGS. 1 to 3, or FIGS. 4 and 5, the fluid pressure cylinder device is configured as follows.
A first chamber 11 formed at one end of a piston 10 inserted into the housing 7 communicates with the atmosphere, and a pressure fluid can be supplied to and discharged from a second chamber 12 formed at the other end of the piston 10. In the fluid pressure cylinder device provided with a spring 15 for urging the piston 10 to the other end side, the first chamber 11 is divided into two passages, a first passage 21 and a second passage 22. The first passage 21 is provided with a first check valve 31 in the first passage 21 and the second check valve 32 is provided in the second passage 22.
The check valve 31 is configured such that the first check member 36 is closed by the first check valve seat 34 by the combined force of the first elastic force and the atmospheric pressure, and the pressure of the first chamber 11 is reduced. When the pressure becomes equal to or higher than the first set pressure P ₁ higher than the atmospheric pressure, the first pressure
The first check member 36 is configured to be opened against the elastic force of the second check valve 32, and the second check valve 32 is a combined force of the second elastic force and the pressure of the first chamber 11 described above. And the second check member 46 is closed by the second check valve seat 44.
The pressure in the first chamber 11 is configured such that the second check member 46 against the second elastic force described above is opened when it becomes the second set pressure P ₂ less lower than the atmospheric pressure.

The invention of claim 1 operates as follows, for example, as shown in FIGS. 1 to 3, or FIGS. 4 and 5. When the fluid pressure cylinder operates, the pressure in the first chamber 11 increases and decreases as the first chamber 11 contracts and expands. As shown in (a) or (b) of FIG.
When the pressure in the chamber 11 is equal to the first set pressure P ₁ (for example,
When the pressure changes in a normal state between 0.7 kgf / cm ² ) and the second set pressure P ₂ (for example, -0.25 kgf / cm ^{2 in} gauge pressure), the first and second two-way check are performed. The valves 31 and 32 are always kept closed.

More specifically, when a pressurized fluid is supplied to the second chamber 12, the piston 10 contracts the first chamber 11 to increase its internal pressure.
Is lower than the set pressure P _1, a first check member 36 is first
The check valve seat 34 is kept closed. Further, the second check member 46 is also moved to the second check valve seat 44 by a combined force of the pressure of the first chamber 11 and the elastic force for closing the valve (here, the elastic force of the second check spring 47). It is kept closed.

Conversely, when the pressure fluid is discharged from the second chamber 12, the first chamber 11 is expanded by the urging force of the spring 15, so that the internal pressure of the first chamber 11 decreases. and go, but the pressure was the decrease is higher than the second set pressure P _2, are kept in a state of the second check member 46 is closed to the second check valve seat 44. In addition, the above-mentioned one check member 36
Is the differential pressure between the inside and outside of the first chamber 11 and the elastic force for closing the valve.
(Here, the elastic force of the first check spring 37) keeps the first check valve seat 34 in a state of being closed and contacted.

As described above, since the first and second two check valves 31 and 32 are always kept in a closed state, a large amount of water-soluble cutting oil is scattered around the housing 7, Even if a large amount of mist-like water droplets are contained in the first chamber 1, these water-soluble cutting oils and mist-like water droplets
Do not enter 1 Similarly, even when a corrosive gas is present in the atmosphere, the corrosive gas is prevented from entering the first chamber 11 by the two check valves 31 and 32.
Can be blocked by

The present invention relates to the above two check valves 31 and 32.
Acts further as follows. For some reason, the pressurized fluid supplied to the second chamber 12 is changed to the above-described first fluid.
When leaking into the chamber 11, the pressure in the first chamber 11 increases as shown in (c) of FIG. In this case, the first chamber 11 contracts and the first set pressure P ₁ (about 0.7
kgf / cm ² ) or more, the first check valve 31 is opened by the pressure. For this reason, it is possible to prevent the pressure in the first chamber 11 from excessively increasing and causing the driving resistance of the piston 10. When the pressure fluid supplied to the second chamber 12 is a liquid such as pressure oil, the following operation and effect can be obtained. That is, the liquid leaked from the second chamber 12 to the first chamber 11 can be automatically discharged from the first check valve 31, so that the first chamber 11 can be prevented from being filled with the liquid.
As a result, it is possible to prevent the cylinder device from being locked by the leaked liquid.

Further, if the first chamber 11 becomes a negative pressure during expansion for some reason, as shown in FIG. 3 (d), the pressure becomes the second set pressure P ₂ (here -0.25). kgf / cm
² ) When the following conditions are satisfied, the second check valve 32 is opened, and the atmosphere is supplied into the first chamber 11. Therefore, it is possible to prevent the first chamber 11 from becoming excessively negative pressure, and prevent the negative pressure from becoming a driving resistance of the piston 10.

(Invention of Claim 2) The invention of Claim 2 is, for example, as shown in FIGS. 4 and 5 of the above, in which the following structure is added to the structure of Claim 1 described above. The first check member 36 is formed in a cylindrical shape, and the first check member 36 is formed in a cylindrical shape.
Is biased toward the first check valve seat 34 by a first check spring 37, and a part of the first passage 21 is provided in the outer peripheral space of the cylindrical first check member 36, Check member 36
The second check valve seat 44 is provided on the peripheral wall portion of the cylindrical hole 36a, and the second check member 46 is urged by the second check spring 47 toward the second check valve seat 44. The outer circumferential space of the second check member 46 and the cylindrical hole 36a constitute a part of the second passage 22.

The second aspect of the invention operates basically in the same manner as the first aspect of the invention, but further operates as follows, for example, as shown in FIGS. The pressure of the first chamber 11 is a first set pressure (for example, about 0.7 kgf / cm ² )
When this occurs, the first check member 36 is separated from the first check valve seat 34 against the first check spring 37. As a result, the pressure in the first chamber 11 is discharged through the outer peripheral space of the second check member 46 and the outer peripheral space of the first check member 36 in order, and the pressure in the first chamber 11 rises excessively. Can be prevented.

When the pressure in the first chamber 11 becomes equal to or lower than a second set pressure (for example, about -0.25 kgf / cm ² ), the second check member 46 is opposed to the second check spring 47. And is separated from the first check member 36. Thereby, the atmosphere outside the housing 7 is supplied to the first chamber 11 through the cylindrical hole 36a of the first check member 36 and the outer peripheral space of the second check member 46 in order, and the first chamber 11 is Excessive negative pressure can be prevented.

(Invention of Claim 3) In the invention of Claim 3, for example, as shown in FIG. 6, the fluid pressure cylinder device is constituted as follows. A first chamber 11 formed at one end of a piston 10 inserted into the housing 7 communicates with the atmosphere, and a pressure fluid can be supplied to and discharged from a second chamber 12 formed at the other end of the piston 10. In the fluid pressure cylinder device provided with a spring 15 for urging the piston 10 to the other end side, the first chamber 11 is divided into two passages, a first passage 21 and a second passage 22. The first valve 31 is provided in the first passage 21, the second valve 32 is provided in the second passage 22, and the first valve 31 is constituted by an open / close valve. Of the second valve 32
Is configured such that the second check member 46 is closed by the second check valve seat 44 by a combined force of the elastic force and the pressure of the first chamber 11, and the pressure of the first chamber 11 is the atmospheric pressure. The second check member 46 is configured to be opened against the above-mentioned elastic force when the pressure becomes lower than the set pressure P ₂ lower than the lower limit pressure P ₂ .

The third aspect of the present invention operates as follows, for example, as shown in FIG. When the fluid pressure cylinder operates, the pressure in the first chamber 11 increases and decreases as the first chamber 11 contracts and expands. If the pressure in the first chamber 11 changes in a normal state higher than the set pressure P ₂ (for example, −0.25 kgf / cm ² ), the first and second two valves 31.
32 is always kept closed. That is, when the pressurized fluid is supplied to the second chamber 12 with the first valve 31 closed, the piston 10 contracts the first chamber 11 to increase its internal pressure. The second check member 46 is kept in a state of being brought into close contact with the second check valve seat 44 by a combined force with the elastic force for use.

Conversely, if the pressure fluid is discharged from the second chamber 12 while the first valve 31 is closed, the first chamber 11 is expanded by the urging force of the spring 15. Although the internal pressure of the first chamber 11 is reduced, the reduced pressure is higher than a set pressure P ₂ (for example, −0.25 kgf / cm ² ). The valve seat 44 is kept in a closed contact state.

As described above, the first and second two valves 31
32 is always kept closed, so that even if a large amount of water-soluble cutting oil is scattered around the housing 7 or a large amount of mist-like water droplets are contained in the atmosphere, Water or mist-like water drops do not enter the first chamber 11. Similarly, even when a corrosive gas is present in the atmosphere, the corrosive gas remains in the first chamber 1.
The entry into 1 can be prevented by the two valves 31 and 32 described above.

The working fluid in the second chamber 12 is supplied to the first chamber 11
If there is a possibility of leakage, the above-mentioned on-off valve 31 is opened prior to the contraction operation of the fluid pressure cylinder in an atmosphere containing a small amount of water-soluble cutting oil or moisture, and in that state, the first chamber is opened. 11 is shrunk. Then, the working fluid that has entered the first chamber 11 is discharged with the above-described contraction, so that the first chamber 11 is prevented from becoming excessively high in pressure, and the fluid pressure cylinder can be driven smoothly. The on-off valve 31 may be closed after the contraction of the first chamber 11 is completed.

For some reason, the first chamber 11 is set at a set pressure P ₂ lower than the atmospheric pressure (for example, −0.25 kgf / c).
m ² ) or less, the pressure difference between the inside and outside of the first chamber 11 causes the second check member 46 to open against the valve-closing elastic force. For this reason, it is possible to prevent the first chamber 11 from becoming excessively negative pressure and to smoothly drive the fluid pressure cylinder.

(Invention of Claim 4) In the invention of Claim 4, for example, as shown in FIG. 7, the fluid pressure cylinder device is constituted as follows. A first chamber 11 formed at one end of a piston 10 inserted into the housing 7 communicates with the atmosphere, and a pressure fluid can be supplied to and discharged from a second chamber 12 formed at the other end of the piston 10. In the fluid pressure cylinder device provided with a spring 15 for urging the piston 10 to the other end side, the first chamber 11 is divided into two passages, a first passage 21 and a second passage 22. The first valve 21 is provided in the first passage 21 and the second valve 32 is provided in the second passage 22, and the first valve 31 is constituted by a check valve. , Its first valve 31
Is configured such that the first check member 36 is closed by the first check valve seat 34 by the combined force of the elastic force and the atmospheric pressure, and the pressure of the first chamber 11 is higher than the atmospheric pressure. against said elastic force when it is set the pressure P ₁ or more configured to first check member 36 described above is opened, the second the
The valve 32 was constituted by an on-off valve.

The invention according to claim 4 operates as follows, for example, as shown in FIG. When the fluid pressure cylinder operates, the pressure in the first chamber 11 increases and decreases as the first chamber 11 contracts and expands. When the pressure in the first chamber 11 changes in a normal state lower than the set pressure P ₁ (for example, 0.7 kgf / cm ² ), the first and second two valves 31.3 are changed.
2 is always kept closed. That is, when the pressure fluid is supplied to the second chamber 12 with the second valve 32 closed, the piston 10 contracts the first chamber 11 to increase its internal pressure, but the pressure is higher than the set pressure P ₁ . Therefore, the first check member 36 is kept in a state in which the first check member 36 is in close contact with the first check valve seat 34.

Conversely, when the pressure fluid is discharged from the second chamber 12 with the second valve 32 closed, the first chamber 11 is expanded by the urging force of the spring 15. The internal pressure of the first chamber 11 is reduced. As a result, the first check member 36 is kept in close contact with the first check valve seat 34 by the pressure difference between the inside and outside of the first chamber 11 and the valve closing elastic force.

As described above, the first and second two valves 31
32 is always kept closed, so that even if a large amount of water-soluble cutting oil is scattered around the housing 7 or a large amount of mist-like water droplets are contained in the atmosphere, Water or mist-like water drops do not enter the first chamber 11. Similarly, even when a corrosive gas is present in the atmosphere, the corrosive gas remains in the first chamber 1.
The entry into 1 can be prevented by the two valves 31 and 32 described above.

The pressure fluid in the second chamber 12 is applied to the first chamber 11
If you are leaks to, because the first chamber 11 from the first check valve seat 34 when the increased first check member 36 away to the set pressure P ₁ or more, the first chamber 11 The fluid pressure cylinder can be driven smoothly by preventing an excessively high pressure. Further, when there is a possibility that the pressure in the first chamber 11 becomes lower than the set pressure P ₂ (for example, −0.25 kgf / cm ² ) lower than the atmospheric pressure for some reason, the first chamber 11 is placed in an atmosphere containing a small amount of water-soluble cutting oil or moisture. Prior to the expansion operation of the fluid pressure cylinder, the on-off valve 32 is opened, and in that state, the first chamber 11 is opened.
Inflate. Thus, the first chamber 11 is prevented from becoming excessively negative pressure, and the fluid pressure cylinder can be driven smoothly.

In the invention of each of the above claims, the elastic force for bringing the check member into contact with the check valve seat is as follows.
There may be a case where the check member is urged by an elastic body such as a spring or rubber, and a case where the check member is formed of an elastic body and utilizes its own elastic force. Further, it is preferable that the second set pressure P ₂ is set to a pressure value from a low vacuum range to a medium vacuum range, thereby preventing the inside of the first chamber 11 from becoming a high vacuum.

[0029]

BEST MODE FOR CARRYING OUT THE INVENTION

(First Embodiment) FIGS. 1 to 3 show a first embodiment of the present invention, in which a cylinder device of the present invention is applied to a hydraulic clamp. First, the configuration of the above hydraulic clamp will be described with reference to FIGS. FIG. 1A is a longitudinal sectional view of the hydraulic clamp. FIG. 1 (B) is the same as FIG.
It is an enlarged view of the arrow B part in (A). FIG. 1C is an enlarged view of a portion indicated by an arrow C in FIG. FIG. 2 is a schematic diagram of the hydraulic clamp described above.

The work piece 2 placed on the upper surface of the work pallet 1 is fixed by the clamp member 4 of the hydraulic clamp 3. The clamp member 4 is composed of a rod 5 extending in a vertical direction and an arm 6 fixed on the rod 5. A push bolt 6a is fixed to the tip of the arm 6 so that the height can be adjusted. The housing 7 of the clamp 3 is fixed to the work pallet 1 by a plurality of bolts (not shown).

A piston 10 is inserted into the cylinder hole 9 of the housing 7 in a hermetically sealed manner by an O-ring 14. A spring chamber (first chamber) 11 is formed below the piston 10, and a spring chamber (first chamber) 11 is formed above the piston 10. Working chamber for clamping
(Second chamber) 12 is formed. A return spring 15 is mounted in the spring chamber 11.

When pressure oil is supplied from the pressure oil supply / discharge port 16 to the working chamber 12, the piston 10 is lowered against the return spring 15, and the clamp member 4 fixed to the piston 10 is shown in FIG. And the push bolt 6a presses and fixes the work piece 2 to the work pallet 1. Conversely, when the pressure oil is discharged from the working chamber 12, the piston 10 is raised by the urging force of the spring 15, and the clamped state is released.

Next, the breathing means 18 provided on the hydraulic clamp 3 will be described. The spring chamber 11 communicates with the atmosphere through two passages, a first passage 21 for depressurizing and a second passage 22 for preventing high vacuum. A first check valve 31 is provided in the first passage 21, and a second check valve 31 is provided in the second passage 22.
Is provided with a second check valve 32.

As shown in FIG. 1B, the first check valve 31 includes a first check valve seat 34 and a first check valve chamber arranged in order from the inside to the outside of the spring chamber 11. 35 and the first
Ball-shaped first check member 36 inserted into check valve chamber 35
And the first check spring 37. The first
The check valve chamber 35 is constituted by the internal space of the first sleeve 38 press-fitted and fixed to the peripheral wall 7c of the housing 7. A part of the first passage 21 is constituted by a groove 39 formed on the peripheral surface of the first sleeve 38.

When the pressure in the spring chamber 11 is normal within the set range, the first non-return member 36 is moved to the first non-return by the combined force of the elastic force of the first non-return spring 37 and the atmospheric pressure. The valve seat 34 is closed and contacted. When the pressure in the spring chamber 11 becomes equal to or higher than the first set pressure P ₁ (see (c) or (d) in FIG. 3, here, about 0.7 kgf / cm ² ), Due to the pressure difference between the pressure and the atmospheric pressure, the first
The check member 36 is separated from the first check valve seat 34 against the first check spring 37.

As shown in FIG. 1C, the second check valve 32 includes a second check valve seat 44 and a second check valve chamber arranged in order from the outside to the inside of the spring chamber 11. 45 and the second
The ball-shaped second check member 46 inserted in the check valve chamber 45
And the second check spring 47. The above-described second check valve chamber 45 is constituted by an internal space of a second sleeve 48 which is press-fitted and fixed to the peripheral wall 7c of the housing 7. A plurality of radial holes 49 (only two shown here) extending in the radial direction formed in the second sleeve 48 form a part of the second passage 22.

In a normal state where the pressure of the spring chamber 11 is within a set range, the second check member 4 is formed by the combined force of the elastic force of the second check spring 47 and the pressure of the spring chamber 11.
6 is brought into close contact with the second check valve seat 44. Then, the pressure of the spring chamber 11 is set to a second set pressure P lower than the atmospheric pressure.
₂ (see (d) in FIG. 3, here, about −0.25 kgf / cm ² ) or less, the second check member is pressed by the differential pressure between the atmospheric pressure and the pressure of the spring chamber 11. 46 is separated from the second check valve seat 44 against the second check spring 47.

When cutting the workpiece 2 in a machining center or the like, the hydraulic clamp 3
The cutting fluid is also squirted vigorously around the outer periphery of the sleeve 48, but the ejection pressure of the cutting fluid can be prevented from directly acting on the second check member 46 by the end wall 48a of the sleeve 48. For this reason, it is possible to prevent the second check member 46 from being opened by the above-described jetting pressure of the cutting fluid.

An example of the use of the hydraulic clamp 3 will be described more specifically with reference to the schematic diagram of FIG. First, an unprocessed work piece 2 is placed at a predetermined position on a work pallet 1 at a work changing station. Next, the hydraulic clamp 3 is switched to the clamp state, and the work piece 2 is fixed to the work pallet 1. Subsequently, the work pallet 1 is transferred to the machining station in the machining center in the clamped state, where the work pallet 1 is machined under the condition that a large amount of water-soluble cutting oil is scattered. When the processing is completed, the work pallet 1 is returned to the work changing station, the hydraulic clamp 3 is switched to the unclamped state, and the processed work piece 2 is carried out.

As shown in FIGS. 2 and 3, the operation of the above-described respiratory means 1 when the hydraulic clamp 3 is used.
8 operates as follows. The pressure of the spring chamber 11 is the first
Set pressure P ₁ (here 0.7 kgf / cm ^{2 in} gauge pressure) and second
In the normal state that is between the set pressure P ^₂ (-0.25kgf / cm ₂ gauge pressure in this case), the first and second two check valves 31, 32 are both maintained in the closed state . Therefore, as shown in (a) of FIG. 3, the spring chamber 11 is contracted in the clamped state X and the internal pressure slightly increases (here, 0.
The pressure is about 1 to 0.2 kgf / cm ² ), and in the unclamped state Y, it expands and the above internal pressure almost returns to the atmospheric pressure.

In the clamp state X described above, the first
When the check valve 31 leaks a seat, it operates as shown in FIG. First, the internal pressure of the spring chamber 11 drops to the atmospheric pressure at the end of the clamp state X due to the sheet leakage. Therefore, the spring chamber 11 has a negative pressure when expanded in the unclamped state Y (here, from -0.1 to-
(Pressure of about 0.2 kgf / cm ² ), and when it is contracted in the next clamp state X, the pressure almost rises to the atmospheric pressure. Then, the spring chamber 11
Repeats the above pressure change every time the state is switched between the clamp state X and the unclamped state Y. Also in this case, the second check valve 32 is kept closed.

When the above-mentioned hydraulic clamp 3 is used for a long time, hydraulic oil is accumulated in the spring chamber 11. More specifically, the O-ring 14 for sealing the piston 10 (FIG. 1)
(A)) due to wear and swelling of the working chamber 1
Hydraulic oil in 2 enters the spring chamber 11. Also,
The oil film scraped out by the movement of the piston 10 gradually accumulates at the bottom of the spring chamber 11.

Then, from 30% of the volume of the spring chamber 11
When approximately 60% of the working oil is accumulated, the volume of the gas phase portion in the spring chamber 11 is reduced by the accumulated amount.
As shown in (c), the internal pressure of the spring chamber 11 increases. When the internal pressure exceeds the first set pressure P ₁ (here, about 0.7 kgf / cm ² ) during the contraction in the clamp state X, the first check valve 31 is opened by the pressure and the bottom of the spring chamber 11 is opened. A part of the working oil stored in the part is discharged to the outside of the housing 7. Thereafter, the inner pressure of the spring chamber 11 repeats the pressure change in the in the vicinity of the first set pressure P _1.

Also, depending on how the hydraulic clamp 3 is used, there is a case where substantially the entirety of the spring chamber 11 is filled with hydraulic oil. For example, when the above-mentioned hydraulic clamp 3 is used in an upside down posture as shown in FIG. 2, only the gas in the upper space of the spring chamber 11 is discharged when the first check valve 31 is opened. Hydraulic oil gradually accumulates in the spring chamber 11, and the hydraulic oil is filled to nearly 100% of the volume of the spring chamber 11.

In this case, as shown in FIG. 3D, when the hydraulic clamp 3 is switched to the clamp state X, almost all of the hydraulic oil in the spring chamber 11 is discharged from the first check valve 31. Therefore, at the time of the next expansion in the unclamped state Y, the inside of the spring chamber 11 tends to decrease to a high vacuum. Then, the second check valve 32 is opened and the atmosphere is released from the spring chamber 11.
Since the spring chamber 11 is supplied to the inside, it is possible to prevent the spring chamber 11 from becoming an excessively negative pressure. Therefore, the above-mentioned negative pressure is prevented from becoming the return resistance of the piston 10, and the piston 10 can be quickly returned by the return spring 15. Thereafter, the spring chamber 11, and repeats the same pressure change (a) of the in Figure 3 in the vicinity of the second set pressure P ₂ above.

The hydraulic clamp 3 is switched to the unclamped state Y in the above-described work changing station. The work changing station does not scatter the cutting oil and has a lower humidity than the working station. Even when the second check valve 32 is opened, the amount of cutting oil, moisture, and the like entering the spring chamber 11 is extremely small.

The first embodiment can be changed as follows. The urging force of the check spring 37 of the first check valve 31 is set to a stronger value than in the above-described embodiment, and gas such as air is supplied to the spring chamber 11 at a predetermined pressure (for example, 0.2
It may be configured to always be sealed at a pressure of about kgf / cm ² to several kgf / cm ² ). In this case, since the inside of the spring chamber 11 can be prevented from becoming a negative pressure, the biasing force of the return spring 15 is not canceled by the negative pressure, and the piston 10 can be returned more reliably. It is possible to reliably prevent foreign substances from entering. The gas can be charged from the second check valve 32 into the spring chamber 11 by connecting a gas filling fitting to the radial hole 49 of the second check valve 32.

The sleeves 38 and 48 may be screw-fixed instead of press-fit. The check valves 35 and 45 may be formed directly on the housing 7 without the sleeves 38 and 48. The check valves 31 and 32 described above may be provided on the lower wall 7b instead of being provided on the peripheral wall 7c of the housing 7 as shown.

The material of the ball-shaped check members 36 and 46 may be steel, rubber, plastic, or the like. Further, each of the above-mentioned check members 36 and 46 may have a disk shape or a conical shape instead of the ball shape. Further, each of the check valves 31 and 32 may be a lead type check valve. In this case, the check member is closed and brought into contact with the check valve seat by the elastic force held by the check member. The check valve seat may be formed on the outer peripheral surface or the lower surface of the housing 7.

FIGS. 4, 5, 6, and 7 show a second embodiment, a third embodiment, and a fourth embodiment, respectively, and a configuration different from that of the first embodiment will be described. In these embodiments, members having the same functions as those in the first embodiment will be described with the same reference numerals.

(Second Embodiment) In the second embodiment shown in FIGS. 4 and 5, the breathing means 18 is configured as follows. FIG. 4 is a schematic diagram corresponding to FIG. FIG.
FIG. 1 is a longitudinal sectional view of the breathing means 18, and FIG.
FIG. 2B is a diagram corresponding to FIG. 1C and FIG. The cassette tube 51 is screwed to the peripheral wall 7c of the housing 7. The first check valve chamber 35 and the second check valve chamber 4 are provided in the cassette cylinder 51.
5 are formed in series. A cylindrical first check member 36 is inserted into the first check valve chamber 35, and the first check member 3
6 is urged to the first check valve seat 34 by the first check spring 37. The valve face of the first check member 36 has a cylindrical hole 36
It is constituted by a sealing O-ring 52 fitted to the peripheral wall portion of FIG.

The second check valve chamber 45 has a bottomed cylindrical second
The check member 46 is inserted, and the second check member 46
The check spring 47 urges the sealing O-ring 52. That is, the O-ring 52 constitutes the second check valve seat 44. A plurality of grooves 54 (only two are shown here) formed on the outer periphery of the second check member 46;
A part of the second passage 22 is constituted by the cylindrical hole 36 a of the first check member 36.

The sealing cross-sectional area of the O-ring 52 with respect to the first check valve seat 34 is set to a value larger than the sealing cross-sectional area of the second check member 46 with respect to the O-ring 52. The elastic force of the first check spring 37 is set to a value larger than the elastic force of the second check spring 47.

When the pressure in the spring chamber 11 becomes equal to or higher than the above-described first set pressure P ₁ (0.7 kgf / cm ^{2 in this case} ) in FIG. 3, the difference between the pressure in the spring chamber 11 and the atmospheric pressure is obtained. The first check member 36 is opened by the differential pressure. As a result, the pressure of the spring chamber 11 increases due to the opening gap between the through-hole 55 of the cassette cylinder 51, the plurality of grooves 54 of the second check member 46, and the first check valve seat 34 and the O-ring 52. Each passage of a plurality of grooves 53 (only one is shown here) formed on the outer peripheral surface of the first check member 36 and a plurality of radial holes 56 (only two are shown here) Go through the order
Released to the atmosphere. That is, these passages constitute the above-described first passage 21 for pressure release.

On the other hand, the pressure in the spring chamber 11 is the second set pressure P _{2 in} FIG. 3 (here, -0.25 kgf / cm ² ).
When the pressure drops below, the second check member 46 is opened by the pressure difference between the atmospheric pressure and the spring chamber 11.
As a result, the atmosphere outside the housing 7 is caused by the radial hole 56, the cylindrical hole 36 a of the first check member 36, the open gap between the O-ring 52 and the second check member 46, The gas is supplied to the spring chamber 11 through the respective passages of the groove 54 of the check member 46 and the through hole 55 in order. That is, the second passage 22 for preventing high vacuum described above is formed by these passages.
Is configured.

The above second embodiment can be modified as follows. The second check valve seat 44 may be provided on the peripheral wall of the cylindrical hole 36a at a location different from the O-ring 52, instead of being shared by the sealing O-ring 52. In the second embodiment, various modifications similar to those of the first embodiment can be made. For example, the cassette cylinder 51 may be attached to the lower wall 7b instead of being attached to the peripheral wall 7c.
May be clamped by a spring force instead of clamped by hydraulic pressure.

(Third Embodiment) FIG. 6 shows a third embodiment and is equivalent to FIG. 2 described above. In the third embodiment, an opening / closing valve 31 (first valve) is provided in the first passage 21 for depressurizing, and the above-described second check valve (second valve) is provided in the second passage 22 for preventing high vacuum. 32 are provided. The above on-off valve 31
It can be opened and closed by manual operation or automatic operation, and is used as follows.

When the hydraulic clamp 3 is driven to be clamped at the above-mentioned work changing station, the open / close valve 31 is opened prior to the drive. Then, if hydraulic oil has entered the spring chamber 11 from the clamp operating chamber 12, the hydraulic oil is discharged as the spring chamber 11 contracts. For this reason, it is possible to prevent the spring chamber 11 from being excessively high in pressure and to smoothly drive the hydraulic clamp 3. The on-off valve 31 may be closed after the end of the clamp drive.

The second check valve 32 operates in the same manner as described above. That is, the above-described second set pressure P ₂ (−0.25 kgf / c in this case) of FIG.
m ² ) or less, the second check member 46 is opposed to the second check spring (not shown here) by the second check valve seat 4.
4 away. Therefore, even if a situation occurs in which the working oil from the working chamber 12 fills the spring chamber 11, it is possible to prevent the spring chamber 11 from becoming a high vacuum during the unclamping operation of the hydraulic clamp 3. Driving can be performed smoothly.

The above-mentioned on-off valve 31 may be opened and closed manually or by an actuator such as a pneumatic cylinder, and may be constituted by a valve with an actuator such as a solenoid valve or an electric valve. Good.

(Fourth Embodiment) FIG. 7 shows a fourth embodiment and is a view corresponding to FIG. 2 described above. In the fourth embodiment, the hydraulic clamp 3 is arranged upside down, the first check valve (first valve) 31 is provided in the first passage 21 for depressurizing, and the second check valve 22 is provided in the second passage 22. An on-off valve 32 (second valve) is provided.

The first check valve 31 operates in the same manner as described above. That is, when the pressure in the spring chamber 11 becomes equal to or higher than the above-described first set pressure P ₁ (here, 0.7 kgf / cm ² ) in FIG. 3, the first check member 36 is moved to the first check spring (here, shown in FIG. 3). ) Is separated from the first check valve seat 34. Therefore, when the hydraulic clamp 3 is driven to be clamped at the work changing station, the spring chamber 11 is prevented from being excessively high in pressure, and the clamp drive can be smoothly performed.

The on-off valve 32 has the same configuration as the on-off valve 31 shown in FIG. 6 and is used as follows. When the hydraulic clamp 3 is driven to be unclamped at the above-described work changing station, the open / close valve 32 is opened prior to the unclamping drive. Accordingly, even when a large amount of hydraulic oil from the clamping operation chamber 12 is accumulated in the spring chamber 11, it is possible to prevent the spring chamber 11 from becoming a high vacuum. Therefore, the hydraulic clamp 3
Can be smoothly unclamped.

In each of the above embodiments, the fluid supplied to the working chamber 12 may be another type of liquid or gas instead of the pressure oil. In the embodiments of FIGS. 6 and 7, the clamp 3 may be arranged upside down with respect to the illustrated one. The present invention can also be applied to a clamp that switches to a clamp state by a spring force and switches to an unclamped state by a fluid pressure instead of a clamp that switches to a clamp state by a fluid pressure and switches to an unclamped state by a spring force. The hydraulic cylinder device of the present invention may be applied to another type of device such as a transfer pressing means, instead of being applied to a clamp.

[0065]

【The invention's effect】

(Invention of claim 1) The invention of claim 1 has the following effects. In a normal state where the internal pressure of the spring chamber is within the range of the two set pressures, the first and second two-way check valves are always kept closed, so that a large amount of water-soluble cutting oil around the housing. Even if a large amount of mist-like water droplets are scattered or contained in the atmosphere, these water-soluble cutting oils and mist-like water droplets do not enter the first chamber. Similarly, even when a corrosive gas exists in the atmosphere, the corrosive gas can be prevented from entering the first chamber by the two check valves. Therefore, the sliding surface of the cylinder hole and the sliding surface of the piston can be kept in a good state for a long time, and the fluid pressure cylinder device can be used for a long time without maintenance.

Also, for some reason, the first
When the pressure in the chamber becomes equal to or higher than the first set pressure, the first check valve is opened by the abnormal pressure, so that the pressure in the first chamber can be prevented from becoming the driving resistance of the piston. Further, when the pressure in the first chamber becomes equal to or lower than the second set pressure for some reason, the second check valve is opened and the atmosphere becomes the first set pressure.
Since the first chamber is supplied to the room, it is possible to prevent the first chamber from becoming excessively negative pressure. As a result, it is possible to prevent the negative pressure from becoming a driving resistance of the piston.

(Invention of claim 2) The invention of claim 2 has the following effect in addition to the effect of the invention of claim 1. Since the two valves, the first check valve and the second check valve, can be integrally mounted on the housing, the mounting work does not require much labor as compared with the case where the two check valves are individually mounted.

(Invention of claim 3) The invention of claim 3 basically has the same effect as the above-mentioned invention of claim 1. That is, the atmosphere can be prevented from entering the first chamber.
The sliding surface of the cylinder hole and the sliding surface of the piston can be kept in a good state for a long period of time, and the fluid pressure cylinder device can be used for a long period without maintenance.

When there is a possibility that the working fluid in the second chamber is leaking to the first chamber, the working fluid may be opened and closed prior to the contraction operation of the fluid pressure cylinder in an atmosphere containing a small amount of water-soluble cutting oil or moisture. Keep the valve open. Then, the working fluid that has entered the first chamber is discharged with the above-described contraction, so that the first chamber is prevented from becoming excessively high in pressure, and the fluid pressure cylinder can be driven smoothly. Further, when the pressure in the first chamber becomes lower than the set pressure lower than the atmospheric pressure for some reason, the second check member is opened against the valve-closing elastic force. Thus, the fluid pressure cylinder can be smoothly driven.

(Invention of Claim 4) The invention of claim 4 basically has the same effect as the above-mentioned invention of claim 1. That is, since the atmosphere can be prevented from entering the first chamber, the sliding surface of the cylinder hole and the sliding surface of the piston can be maintained in a good state for a long time, and the fluid pressure cylinder device can be maintained for a long time. Free to use.

When the working fluid in the second chamber leaks to the first chamber for some reason, when the first chamber rises to a set pressure or more, the first check valve seat moves from the first check valve seat to the first chamber. Since the one check member is separated, the fluid pressure cylinder can be smoothly driven by preventing the first chamber from being excessively high in pressure. Further, when there is a possibility that the first chamber may be under a negative pressure for some reason, the on-off valve is opened prior to the expansion operation of the fluid pressure cylinder under an atmosphere with a small amount of water-soluble cutting oil or moisture, and the The first chamber is expanded in the state. Thus, the first chamber is prevented from becoming excessively negative pressure, and the fluid pressure cylinder can be driven smoothly.

[Brief description of the drawings]

FIG. 1 shows a first embodiment of the present invention. FIG. 1 (A)
1 is a longitudinal sectional view of a hydraulic clamp to which a hydraulic cylinder device is applied. FIG. 1B is an enlarged view of an arrow B portion in FIG. 1A. FIG. 1C is an enlarged view of a portion indicated by an arrow C in FIG.

FIG. 2 is a schematic view of the above hydraulic clamp.

FIG. 3 is a diagram illustrating the operation of the hydraulic clamp according to the first embodiment.

FIG. 4 is a schematic view of a hydraulic clamp according to a second embodiment of the present invention, and is a view corresponding to FIG. 2 described above.

FIG. 5 is a longitudinal sectional view of a breathing means provided in a hydraulic clamp of the second embodiment.

FIG. 6 is a view showing a third embodiment of the present invention and corresponding to FIG. 2 described above.

FIG. 7 shows a fourth embodiment of the present invention and is a view corresponding to FIG.

[Explanation of symbols]

Reference numeral 7: housing, 10: piston, 11: first chamber (spring chamber), 12: second chamber (operating chamber for clamping), 15: spring (return spring), 21: first passage, 22: second passage, 31 ... first check valve (first valve), 32 ... second check valve (second valve), 34 ...
1st check valve seat, 36 ... 1st check member, 36a ... cylindrical hole, 3
7 ... first check spring (first elastic force), 44 ... second check valve seat,
46: second check member, 47: second check spring (second elastic force), P ₁ : first set pressure, P ₂ : second set pressure.

Claims (4)

[Claims] 1. A piston inserted into a housing (7)
A first chamber (11) formed at one end of (10) communicates with the atmosphere and a second chamber (11) formed at the other end of the piston (10).
A spring configured to supply and discharge a pressure fluid to and from the chamber (12) and to urge the piston (10) to the other end.
In the hydraulic cylinder device provided with (15), the first chamber (11) is connected to a first passage (21) and a second passage (22).
The first passage (21) is provided with a first check valve (31) and the second passage (22) is connected to a second check valve (32) through the two passages (1) and (2). The first check valve (31) is configured such that the first check member (36) is connected to the first check valve seat (3) by the combined force of the first elastic force and the atmospheric pressure.
4) so as to be closed by the first chamber (11).
Against the first elastic force of the when the pressure of becomes the first set pressure (P ₁₎ or more higher than the atmospheric pressure configured to first check member of (36) is opened The second check valve (32) is provided with a second elastic force and the first
The second check member (46) is configured to be closed by the second check valve seat (44) by a resultant force with the pressure of the chamber (11), and the pressure of the first chamber (11) is higher than the atmospheric pressure. Lower second set pressure
(P ₂ ) The second check member (46) is opened against the second elastic force when the value becomes (P ₂ ) or less.
A fluid pressure cylinder device characterized by the above-mentioned. 2. The hydraulic cylinder device according to claim 1, wherein the first check member (36) is formed in a cylindrical shape, and the first check member (36) is formed into a first shape. A part of the first passage (21) is urged by the check spring (37) toward the first check valve seat (34) in the outer peripheral space of the cylindrical first check member (36). The second check valve seat (44) is provided on a peripheral wall portion of the cylindrical hole (36a) of the first check member (36), and the second check member is provided.
(46) is urged by the second check spring (47) toward the second check valve seat (44), and the outer circumferential space of the second check member (46) and the cylindrical hole (36a) are The second passage (22)
A fluid pressure cylinder device, comprising a part of the fluid pressure cylinder device. 3. A piston inserted in a housing (7).
A first chamber (11) formed at one end of (10) communicates with the atmosphere and a second chamber (11) formed at the other end of the piston (10).
A spring configured to supply and discharge a pressure fluid to and from the chamber (12) and to urge the piston (10) to the other end.
In the hydraulic cylinder device provided with (15), the first chamber (11) is connected to a first passage (21) and a second passage (22).
The first passage (21) is provided with a first valve (31), and the second passage (22) is provided with a second valve (32) through the two passages (2) and (3). The first valve (31) is constituted by an on-off valve, and the second valve (32) is configured such that the second check member (46) is formed by the combined force of the elastic force and the pressure of the first chamber (11). The first check valve seat (44) is configured to be closed by the first chamber (1).
When the pressure of (1) becomes equal to or lower than the set pressure (P ₂ ) lower than the atmospheric pressure, the second check member (4) is opposed to the elastic force.
(6) The fluid pressure cylinder device is configured to be opened. 4. A piston inserted in a housing (7).
A first chamber (11) formed at one end of (10) communicates with the atmosphere and a second chamber (11) formed at the other end of the piston (10).
A spring configured to supply and discharge a pressure fluid to and from the chamber (12) and to urge the piston (10) to the other end.
In the hydraulic cylinder device provided with (15), the first chamber (11) is connected to a first passage (21) and a second passage (22).
The first passage (21) is provided with a first valve (31), and the second passage (22) is provided with a second valve (32) through the two passages (2) and (3). The first valve (31) is constituted by a check valve, and the first valve (31) is the first valve (31) by the combined force of the elastic force and the atmospheric pressure.
The check member (36) is configured to be closed by the first check valve seat (34), and the pressure of the first chamber (11) becomes equal to or higher than a set pressure (P ₁ ) higher than the atmospheric pressure. When the first check member (36) is opened against the elastic force, the second valve (32) is constituted by an on-off valve,
A hydraulic cylinder device characterized by the above-mentioned.