JP2765504B2 - Press machine equalizer - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pressure equalizing device for a press machine, and more particularly, to a hydraulic pressure in a hydraulic cylinder for pressure equalization which temporarily decreases during press working, and more hydraulic oil than necessary passes through a check valve. The present invention relates to a technique for preventing an incoming pumping phenomenon.

[0002]

[Prior art]

(A) a plurality of hydraulic cylinders in which oil chambers are communicated with each other; and (b) an oil supply which is connected to the plurality of hydraulic cylinders via an oil supply passage and supplies hydraulic oil to the hydraulic cylinders at a predetermined oil supply pressure. Means, (c) disposed in the refueling oil passage;
A check valve that allows the flow of hydraulic oil from the oil supply means side to the hydraulic cylinder side and prevents the flow in the opposite direction, and the cylinder oil pressure in the hydraulic cylinder is equal to or less than the oil supply pressure prior to press working. The predetermined initial hydraulic pressure is
2. Description of the Related Art There has been known a pressure equalizing device for a press machine in which the pistons of a plurality of hydraulic cylinders are driven into a neutral state during press working so that a load is evenly distributed through the plurality of hydraulic cylinders. JP-A-5-5736
The apparatus described in Japanese Patent Publication No. 3 is an example of such an arrangement, in which the plurality of hydraulic cylinders are arranged on a cushion pad to which a wrinkle pressing load is applied by a wrinkle pressing load applying unit, and the hydraulic cylinders are provided on the hydraulic cylinder. Cushion pins are respectively arranged to support the wrinkle presser die, and the hydraulic oil of the hydraulic cylinder is elastically compressed by the wrinkle press load during press working, and the pistons are respectively driven into a neutral state. By doing so, the wrinkle holding load is evenly transmitted to the plurality of cushion pins via the hydraulic cylinder. As a result, regardless of the length variation of the cushion pins or the inclination of the cushion pad, the wrinkle holding load is transmitted from each cushion pin evenly to the wrinkle holding type, and the wrinkle holding is performed with the load distribution according to the cushion pin distribution. Is performed.

[0003] The initial hydraulic pressure of the hydraulic cylinder is set so that the pistons of all the hydraulic cylinders are in a neutral state at the time of press working irrespective of the variation in the length of the cushion pin as described above. It is determined by calculating or performing trial hitting in accordance with an arithmetic expression so as not to be driven inward and to reach the end of the stroke. Also, the check valve is designed so that even if the hydraulic pressure in the hydraulic cylinder becomes high during the press working, the hydraulic oil does not flow back to the oil supply means side, and always before the press working regardless of the oil leakage of the hydraulic cylinder etc. This is to make the hydraulic pressure in the hydraulic cylinder equal to the initial hydraulic pressure. Such a check valve is usually provided with an urging means such as a spring for urging the valve body toward the valve closing side, and opens the valve to the hydraulic cylinder side against the urging force of the urging means. Since the hydraulic oil flows, a hydraulic pressure drop occurs in accordance with the urging force of the urging means, and the cylinder oil pressure (initial oil pressure) in the hydraulic cylinder before press working becomes lower than the oil pressure of the oil supply means by the oil pressure drop. For example, if the supply oil pressure of the oil supply means is P ₀ , the cylinder oil pressure is P, and the hydraulic pressure drop by the urging force of the urging means is P _S , the condition is satisfied when the following expression (1) is satisfied. Hydraulic oil flows to the hydraulic cylinder side through. P = P ₀ −P _S (1)

[0004] By the way, during press working, the cylinder oil pressure is increased by the displacement of the piston. However, in the early stage of the press work, the hydraulic pressure suddenly fluctuates up and down due to the impact of the movable type collision. A pumping phenomenon in which hydraulic oil flows into the hydraulic cylinder side may occur. That is, the cylinder oil pressure P on the left side in the above equation (1) temporarily decreases, and the oil pressure on the right side (P ₀ −
P _s ), which also occurs for non-return valves without biasing means. If such a pumping phenomenon is repeated for each press working, the cylinder oil pressure before the press working, that is, the initial oil pressure gradually increases, and a problem occurs such that an equalized pressure state in which the load is evenly distributed cannot be obtained. For this reason, in the device described in Japanese Patent Application Laid-Open No. 5-57363, an electromagnetic on-off valve is provided between the hydraulic cylinder and the check valve, and in the event of a movable collision, the valve is closed to shut off the oil passage between the two. This prevents the pumping phenomenon from occurring, and opens the electromagnetic on-off valve when the movable mold reaches the bottom dead center.

[0005]

However, the hydraulic pressure on the hydraulic cylinder side is, for example, 4 due to the impact during press working.
Since the pressure reaches an extremely high pressure of about 00 × 9.8 × 10 ⁴ Pa (400 kgf / cm ² ), there is a problem that the durability of the solenoid on-off valve cannot be sufficiently obtained. In addition, the opening and closing control of this solenoid on-off valve is one shot (one press working)
Since the opening and closing of the solenoid on-off valve is performed in the process of press working with high oil pressure as described above, the durability is further reduced due to wear of the valve body and the reliability of the device is impaired. .

The present invention has been made in view of the above circumstances, and an object of the present invention is to prevent a pumping phenomenon while maintaining sufficient durability.

[0007]

According to a first aspect of the present invention, there is provided a fuel cell system comprising: (a) a plurality of hydraulic cylinders; (b) oil supply means; and (c) a check valve. Prior to press working, the cylinder oil pressure in the hydraulic cylinder is set to a predetermined initial oil pressure equal to or less than the supply hydraulic pressure, and the pistons of the plurality of hydraulic cylinders are driven into a neutral state during press working, respectively. In a pressure equalizing device of a press machine for evenly distributing a load through the plurality of hydraulic cylinders, (d) the pressure equalizer is disposed closer to the oil supply means than the check valve, and the cylinder oil pressure is lower than the initial oil pressure. And (e) suspending the function of the inflow prevention means before press working, and the cylinder oil pressure is controlled by the cylinder oil pressure. Allowing be pressed in the period hydraulic adjustment, but at least pressing the initial and having a inflow prevention control means for operating the inflow preventing means.

[0008]

In such a pressure equalizing device of a press machine,
Before the press working, the hydraulic oil is supplied from the oil supply means to the hydraulic cylinder side through the check valve, so that the cylinder oil pressure is adjusted to a predetermined initial oil pressure based on the oil supply pressure of the oil supply means. That is, if the check valve does not include the urging means for urging the valve body toward the valve closing side, the initial oil pressure is adjusted to substantially the same oil pressure as the supply oil pressure, and if the urging means is provided, As shown in the equation (1), the pressure is adjusted to be lower by the hydraulic pressure drop due to the urging force. Thereby, at the time of press working, the pistons of the plurality of hydraulic cylinders are respectively driven into a neutral state, and a pressure equalized state in which the load is evenly distributed through the plurality of hydraulic cylinders is obtained.

On the other hand, at least at the beginning of the press working, the inflow prevention means is operated by the inflow prevention control means,
Even if the cylinder oil pressure falls below the initial oil pressure, pumping in which hydraulic oil flows from the oil supply means side to the hydraulic cylinder side through the check valve is prevented. During press working, the piston hydraulic pressure increases due to the piston being driven.However, in the early stage of the press working, the impact due to the collision of the movable mold causes a sudden fluctuation in hydraulic pressure, and the cylinder hydraulic pressure temporarily drops below the initial hydraulic pressure. On the other hand, in the present invention, even if the cylinder oil pressure becomes lower than the initial oil pressure, the inflow of the operating oil to the hydraulic cylinder side is prevented by the inflow prevention means.

Further, in the present invention, since the inflow prevention means is arranged closer to the oil supply means than the check valve, a large hydraulic pressure unlike the hydraulic cylinder side does not act, and high durability can be obtained. Become like Since the inflow prevention means is disposed closer to the oil supply means than the check valve, a large hydraulic pressure on the hydraulic cylinder side acts on the check valve. Since the valve is seated on the valve seat to prevent reverse flow, the structure is simpler than that of the electromagnetic on-off valve, and sufficient durability can be obtained even under high pressure, and excellent durability can be obtained as a whole device.

The above is a function specific to the present invention. As the inflow prevention means, a pressure reducing valve for lowering the oil pressure on the oil supply means side than the oil supply oil pressure, a connection and cutoff of the oil supply oil passage, and a non-return when shut off. A pressure reducing means such as an electromagnetic switching valve for draining the hydraulic oil on the valve side is preferably used, but an electromagnetic opening / closing valve which merely connects and disconnects the oil supply passage may be employed.

[0012]

As described above, according to the present invention, even if the cylinder oil pressure temporarily becomes lower than the initial oil pressure due to the sudden fluctuation of the hydraulic pressure at the initial stage of the press working due to the impact due to the collision of the movable mold, etc. Since pumping in which the hydraulic oil flows from the oil supply means side to the hydraulic cylinder side is prevented, an increase in the initial hydraulic pressure accompanying the inflow of the hydraulic oil is avoided, and a stable pressure equalization state can be obtained. In addition, since the inflow prevention means is disposed closer to the oil supply means than the check valve, excellent durability can be obtained as a whole of the apparatus, and the pressure equalization state can be stably obtained as described above. This improves the reliability of the device.

[0013]

According to a second aspect of the present invention, in the pressure equalizing apparatus for a press machine according to the first aspect of the present invention, the inflow prevention means reduces the oil pressure on the oil supply means side with respect to the check valve. It is characterized by having a decompression means.

[0014]

The second invention is a pressure reducing valve for lowering the oil pressure on the oil supply means side than the check valve to a level lower than the oil pressure, and a check valve for connecting and shutting off the oil supply passage and shutting off. The inflow prevention means is configured to include a pressure reducing means such as an electromagnetic switching valve for draining the hydraulic oil on the side, and in this way, the inflow of the hydraulic oil to the hydraulic cylinder side can be more reliably prevented. . That is, for example, when the oil supply oil passage is simply connected / disconnected by the electromagnetic on-off valve, the cylinder oil pressure becomes lower than the initial oil pressure because the supply oil pressure is maintained between the electromagnetic on-off valve and the check valve. In this case, the hydraulic oil slightly flows into the hydraulic cylinder. There is no problem if the inflow amount is smaller than the oil leakage amount of the hydraulic cylinder or the like. However, if the inflow amount is larger than the oil leakage amount, the initial oil pressure gradually increases, which is not preferable.

[0015]

According to a third aspect of the present invention, in the pressure equalizing device for a press machine according to the second aspect of the present invention, the inflow prevention means is connected in parallel with the (d-1) oil supply passage. (D-2) provided in the parallel oil passage, and a pressure reducing means for reducing the pressure to a hydraulic pressure lower than the supply hydraulic pressure. Switching means for switching between a state in which the operating oil is supplied from the oil supply path and a state in which the operating oil is supplied from the parallel oil path; and before the press working, the operation oil is supplied from the oil supply path. At the beginning of machining, the switching means is controlled so that hydraulic oil is supplied from the parallel oil passage.

[0016]

In the pressure equalizing apparatus for a press machine, the switching means is switched so that the hydraulic oil is supplied from the oil supply passage to the check valve before the press working. While the cylinder oil pressure is adjusted to a predetermined initial oil pressure based on the supply oil pressure, the switching means is switched so that hydraulic oil is supplied from the parallel oil passage to the check valve at the initial stage of the press working, and the parallel oil passage is changed. The pressure which is lower than the supply pressure by the pressure reducing means provided in the first valve is applied to the check valve. Therefore, similarly to the second aspect of the present invention, the inflow of the hydraulic oil to the hydraulic cylinder side due to the hydraulic pressure fluctuation at the initial stage of the press working is more reliably prevented. Moreover, in the present invention, the oil passage need only be switched by the switching means, so that the oil pressure can be changed more quickly than when, for example, a hydraulic pressure control is performed by providing a proportional electromagnetic relief pressure reducing valve in the oil supply oil passage. There are advantages that excellent responsiveness can be obtained and that the device can be configured at low cost.

The functions and effects unique to the third invention have been described above.
In carrying out the first and second inventions, the proportional electromagnetic relief pressure reducing valve may be interposed in the oil supply passage as inflow prevention means, in which case the discharge pressure (secondary oil pressure) can be arbitrarily changed. Therefore, before the press working, the pressure is reduced so as to be the supply pressure, and at the beginning of the press working, the discharge pressure may be changed so as to be lower than the supply hydraulic pressure. That is,
Since the proportional electromagnetic relief pressure reducing valve also serves as a part of the oil supply means for supplying the hydraulic oil with a predetermined oil supply pressure, the configuration of the hydraulic circuit including the oil supply means can be simplified.

[0018]

A fourth aspect of the present invention is directed to a fourth aspect of the present invention, wherein: (a) a plurality of hydraulic cylinders;
(C) a check valve, and prior to press working, the cylinder oil pressure in the hydraulic cylinder is set to a predetermined initial oil pressure equal to or less than the supply hydraulic pressure, and during press working, the pistons of the plurality of hydraulic cylinders are driven in respectively. In the pressure equalizing device of the press machine which distributes the load evenly through the plurality of hydraulic cylinders by being in the neutral state, (f) reducing the amount of hydraulic pressure drop by the check valve to the initial hydraulic pressure (G) increasing the hydraulic pressure drop amount by the hydraulic pressure drop increasing means before press working, and adjusting the cylinder oil pressure to the initial oil pressure. Although it is permissible, at least in the initial stage of the press working, there is provided a hydraulic pressure drop control means for increasing the hydraulic pressure drop by the hydraulic pressure drop increasing means.

[0019]

In such a pressure equalizing device of a press machine,
Before the press working, hydraulic oil is supplied from the oil supply means to the hydraulic cylinder side through the check valve, whereby the cylinder oil pressure is adjusted to a predetermined initial oil pressure based on the oil supply pressure of the oil supply means. At the time of machining, the pistons of the plurality of hydraulic cylinders are driven into each other, and a pressure equalized state where a neutral state is obtained is obtained. On the other hand, at least in the early stage of pressing,
The hydraulic pressure drop increasing means is operated by the hydraulic pressure drop controlling means, and the amount of hydraulic pressure drop by the check valve is increased. That is, the hydraulic pressure drop amount P _S in the above equation (1) is increased, and if the increase is ΔP _S , the supply hydraulic pressure P _S
0 from the hydraulic drop amount (P _S + ΔP _S) and minus pressure (P ₀
-P _S -ΔP _S ), the hydraulic oil flows into the hydraulic cylinder side when the cylinder oil pressure P becomes lower than. In other words, the cylinder oil pressure at the time of pressure adjustment before press working (initial oil pressure)
If the cylinder oil pressure P does not further decrease by an increase ΔP _S of the oil pressure drop amount than P = P ₀ −P _S , the hydraulic oil does not flow into the hydraulic cylinder through the check valve, and the press working is performed. Initially, the cylinder oil pressure P temporarily becomes the initial oil pressure (P
Even if ₀ -P _S) lower than, further unless reduced increment [Delta] P _S or hydraulic pressure of the hydraulic drop, pumping phenomenon hydraulic oil to the hydraulic cylinder side flows does not occur.

Further, since the present invention increases the amount of hydraulic pressure drop of the check valve by the hydraulic pressure drop increasing means, the durability of the check valve is lower than that of the case where an electromagnetic on-off valve is provided on the hydraulic cylinder side of the check valve. improves. The check valve has a simpler structure than a solenoid on-off valve and has sufficient durability against high pressure, so even if high hydraulic pressure on the hydraulic cylinder side acts directly on the check valve, Excellent durability is obtained as a whole. Further, the apparatus can be configured at a lower cost as compared with a case where pumping is prevented by reducing the oil pressure by a pressure reducing valve.

The above is the operation unique to the present invention. As the hydraulic pressure drop increasing means, for example, the urging force (preload) of the urging means such as a spring for urging the valve body of the check valve toward the valve closing side is used. And a plurality of check valves having biasing means having different biasing forces connected in parallel and switching the connection state of the oil passage by an electromagnetic switching valve can be adopted. At the time of pressure adjustment before press working in which the cylinder oil pressure is adjusted to the initial oil pressure, the amount of hydraulic pressure drop of the check valve is almost zero, and in the early stage of press working, a valve body is urged by an urging means to cause a hydraulic pressure drop. good.

[0022]

As described above, according to the present invention, since the hydraulic pressure drop of the check valve is increased by the hydraulic pressure drop increasing means at the beginning of the press working, even if the cylinder oil pressure becomes lower than the initial oil pressure, the oil pressure drop is further increased. As long as the hydraulic pressure does not decrease by the amount of increase, hydraulic oil does not flow into the hydraulic cylinder side,
An increase in the initial oil pressure accompanying the inflow of the hydraulic oil is avoided, and the pressure equalization state can be stably obtained. Further, since only the amount of hydraulic pressure drop of the check valve is increased by the hydraulic pressure drop increasing means, high durability can be obtained as a whole of the apparatus, and the pressure equalization state can be stably obtained as described above. Together, the reliability of the device is improved. Further, there is an advantage that the apparatus can be configured at a lower cost as compared with the case where the oil pressure is reduced by the pressure reducing valve.

[0023]

Embodiments of the present invention will be described below in detail with reference to the drawings. In the press machine 10 shown in FIG. 1, the bolster 14 to which the punch mold 12 is attached is positioned and fixed at a predetermined position on the bed 16, while the slide plate 20 to which the die 18 is attached is moved up and down by an elevation drive means (not shown). It has become. The bolster 14 is provided with a large number of through holes 26 for disposing the cushion pins 24, and a cushion pad 28 for supporting the cushion pins 24 is disposed below the bolster 14. . Cushion pin 24
Is a wrinkle presser die 30 disposed together with the punch die 12.
And an arbitrary number are provided at predetermined positions predetermined according to the shape of the wrinkle presser die 30 and the like. The punch die 12, the die die 18, and the wrinkle press die 30 constitute a press die. The die die 18 is a movable die, and the punch die 12 is a stationary die. Then, while the peripheral portion of the press material 29 is wrinkled and held by the die 18 and the wrinkle pressing die 30, drawing is performed by the punch die 12 and the die 18.

The cushion pad 28 has a through hole 26
, A plurality of hydraulic cylinders 32 are provided, and the lower ends of the cushion pins 24 are respectively mounted on piston rods of the hydraulic cylinder 32. The cushion pad 28 can be moved up and down while being guided by a guide (not shown), and is constantly urged upward by an air cylinder 34 functioning as a wrinkle pressing load applying means. When the mold 18 comes in contact with the press material 29 and the wrinkle press die 30 is lowered together with the die 18, the wrinkle press load of a size corresponding to the pressure receiving area of the air chamber 36 of the air cylinder 34 and the air pressure is applied. The pad 28 is made to act on the wrinkle presser die 30 via the cushion pin 24. The air pressure in the air chamber 36 is adjusted according to the wrinkle holding load.

The plurality of hydraulic cylinders 32 are provided with a pressure equalizing device 4.
0, the oil chambers thereof are communicated with each other, and the pistons of all the hydraulic cylinders 32 involved in the press working, that is, the pistons of all the hydraulic cylinders 32 on which the cushion pins 24 are arranged, are respectively pressed. By being driven into the neutral state during processing, the wrinkle pressing load is evenly transmitted to each cushion pin 24 via the hydraulic cylinder 32. The hydraulic cylinder 32 is connected to the oil supply passage 4.
Hydraulic oil is supplied via a proportional electromagnetic relief pressure reducing valve 46 and a check valve 48, which are connected to a hydraulic pressure source 44 such as a pump via a pump 2 and can control a discharge pressure (secondary hydraulic pressure). The cylinder oil pressure P in the hydraulic cylinder 32 is adjusted according to the discharge pressure of the proportional electromagnetic relief pressure reducing valve 46.
The check valve 48 is provided with the spring 50 as an urging means for urging a valve body such as a ball or a poppet toward the valve closing side. When the amount to P _S, the cylinder pressure P
Is the hydraulic pressure minus the pressure drop amount P _S from the discharge pressure of the proportional electromagnetic relief pressure reducing valve 46.

The discharge pressure of the proportional electromagnetic relief pressure reducing valve 46 is controlled by a controller 5 having a microcomputer or the like.
2 is controlled. Press stroke detection means 54 such as a limit switch is connected to the controller 52, and the movable type of the press machine 10, that is, the die type 1
The stroke signal SS is turned on at a position slightly before the press start position at which the sheet No. 8 comes into contact with the press material 29, and turned off when reaching the same height position after reaching the bottom dead center.
Is supplied. The controller 52 repeatedly executes the steps shown in FIG. 2 at a predetermined cycle time. First, at step S1, it is determined whether or not the stroke signal SS is ON.
3 while the first hydraulic pressure P ₁ of the discharge pressure, the second pressure P ₂ and the discharge pressure in step S2 when the stroke signal SS is ON, oil pressure of the check valve 48 side in any case is its discharge pressure The exciting current of the proportional electromagnetic relief pressure reducing valve 46 is controlled so as to be as follows. If necessary, an oil pressure sensor may be provided in the oil supply oil passage 42, and the proportional electromagnetic relief pressure reducing valve 46 may be feedback-controlled so as to obtain a target oil pressure value.

The first hydraulic pressure P ₁ is a hydraulic pressure (P ₁ −P _{S) in which} the cylinder hydraulic pressure before press working, that is, the initial hydraulic pressure, is lower than the first hydraulic pressure P ₁ by a hydraulic pressure drop P _S by the spring 50 of the check valve 48. ), All the hydraulic cylinders 32 involved in the press working during the press working
An arithmetic expression is set in accordance with the press working conditions such as the number of cushion pins 24 used and the wrinkle holding load so that the piston of FIG. Is determined in accordance with a request or a trial beating. Also, the second
Hydraulic P ₂ is the pressing initial die 18 even if the vertical movements cylinder pressure P is rapidly by the impact when colliding with the blank-holding die 30 across the press material 29, the check valve 4
In order to prevent a pumping phenomenon in which the hydraulic oil flows into the hydraulic cylinder 32 through the pump 8, a predetermined oil pressure lower than the first oil pressure P ₁ or a predetermined constant oil pressure sufficiently lower than the first oil pressure P ₁ is set. Is done. The controller 52 includes:
A storage means for storing the first oil pressure P ₁ and the second oil pressure P ₂ is provided, and input operation means for inputting the oil pressures P ₁ and P ₂ , or press working conditions etc. are inputted. A computing means for computing the hydraulic pressures P ₁ and P ₂ is provided. Incidentally, the first oil pressure P ₁ corresponds to the oil supply pressure P ₀ in the equation (1).

In such a pressure equalizing device 40, the stroke signal SS of the press stroke detecting means 54 is OF
During non-press working of F, proportional solenoid relief pressure reducing valve 4
Discharge pressure of 6 is the first oil pressure P _1, the cylinder pressure P according to the first hydraulic pressure P ₁ is a predetermined initial oil pressure (P ₁ -P _S)
Is regulated. As a result, during the press working, the pistons of the hydraulic cylinders 32 involved in the press working are each driven into a neutral state, and regardless of the variation in the length of the cushion pin 24 and the inclination of the cushion pad 28, the hydraulic cylinder 32 The wrinkle pressing load is evenly transmitted to each cushion pin 24 via the.

On the other hand, during the press working in which the stroke signal SS of the press stroke detecting means 54 is turned on, the discharge pressure of the proportional electromagnetic relief pressure reducing valve 46 is set to the second oil pressure P ₂ lower than the first oil pressure P ₁ , hydraulic is pressurized second hydraulic P ₂ two adjustment thereof between the electromagnetic relief pressure reducing valve 46 and the check valve 48. During the press working, the cylinder hydraulic pressure P increases due to the piston being driven. However, in the initial stage of the press working, the impact caused by the collision of the die 18 causes a rapid fluctuation of the hydraulic pressure, so that the cylinder hydraulic pressure P temporarily decreases before the press working. May be lower than the initial hydraulic pressure (P ₁ −P _S ), whereas in the present embodiment, the hydraulic pressure between the check valve 48 and the proportional electromagnetic relief pressure reducing valve 46 is the first hydraulic pressure P as described above. _{Since the} pressure is adjusted to the second oil pressure P ₂ lower than ₁ , the cylinder oil pressure P
Is less than the initial oil pressure (P ₁ -P _S ), the check valve 4
The occurrence of a pumping phenomenon in which hydraulic oil flows into the hydraulic cylinder 32 through the pump 8 is prevented. In particular, in this embodiment, since the hydraulic pressure between the check valve 48 and the proportional electromagnetic relief pressure reducing valve 46 is reduced, pumping is more facilitated than when the oil passage is simply shut off by the electromagnetic on-off valve. As a result, pumping does not occur unless the cylinder oil pressure P becomes lower than the oil pressure (P ₂ −P _S ).

In this embodiment, since the proportional electromagnetic relief pressure reducing valve 46 for preventing pumping is disposed closer to the hydraulic power source 44 than the check valve 48, the hydraulic cylinder 3
A large oil pressure does not act as in the case of the second side, and higher durability can be obtained as compared with a conventional device in which an electromagnetic on-off valve is arranged between the hydraulic cylinder 32 and the check valve 48.
The large hydraulic pressure on the hydraulic cylinder 32 side acts directly on the check valve 48. However, the check valve 48 is a valve body such as a ball or a poppet seated on a valve seat to prevent a reverse flow. Compared to the solenoid on-off valve, the structure is simpler, sufficient durability can be obtained even at high pressure, and excellent durability can be obtained as a whole device.

As described above, in this embodiment, the hydraulic pressure suddenly fluctuates up and down in the early stage of the press working due to an impact due to the collision of the die 18 and the like, and the cylinder hydraulic pressure P temporarily becomes the initial hydraulic pressure (P ₁ -P _S ). Even if the pressure becomes lower, the pumping of the hydraulic oil flowing into the hydraulic cylinder 32 through the check valve 48 is prevented, so that the initial hydraulic pressure is not increased due to the flow of the hydraulic oil, and the pressure equalization state is stabilized. To be obtained.
Further, since the proportional electromagnetic relief pressure reducing valve 46 is disposed closer to the hydraulic pressure source 44 than the check valve 48, excellent durability can be obtained as a whole of the apparatus, and the pressure equalizing state is maintained as described above. The reliability of the device is improved in combination with the fact that it is obtained stably.

On the other hand, in this embodiment, the proportional pressure relief valve 46 is used to regulate the first hydraulic pressure P ₁ and the second hydraulic pressure P ₂ in accordance with the operation timing of the press machine 10, so that the pressure equalized state is achieved. In addition, since pumping is prevented and the pumping is prevented, there is an advantage that the configuration of the hydraulic circuit is greatly simplified and the hydraulic circuit can be arranged compactly.

This embodiment is an example of the second aspect of the present invention. The proportional electromagnetic relief pressure reducing valve 46 corresponds to a pressure reducing means as inflow prevention means. It is configured refueling unit by the first hydraulic P ₁ corresponds to the supply pressure of the hydraulic oil of the oil supply means. Further, the controller 52 and the press stroke detecting means 54 constitute an inflow prevention control means.

Next, another embodiment will be described. In the following embodiments, portions substantially common to the first embodiment are denoted by the same reference numerals, and detailed description is omitted.

The pressure equalizing device 60 shown in FIG. 3 is provided in a first portion 42a of the oil supply passage 42 between the check valve 48 and the hydraulic pressure source 44, instead of the proportional electromagnetic relief pressure reducing valve 46. It has a pressure reducing valve 62 and a second pressure reducing valve 66 provided in a parallel oil passage 64 connected in parallel to the oil supply oil passage 42a. The connection state is determined by the electromagnetic switching valve 6 provided near the check valve 48.
8 for switching. First pressure reducing valve 62 and the second pressure reducing valve 66 are both being adapted to adjust the discharge pressure manually, the discharge pressure of the first pressure reducing valve 62 is adjusted to the first hydraulic P _1, second pressure reducing discharge pressure of the valve 66 is adjusted to the second pressure P _2. When the stroke signal SS is OFF, the controller 70 that controls the electromagnetic switching valve 68 stops outputting the drive signal, connects the refueling oil passage 42a to the check valve 48, and outputs the stroke signal S
When S is ON, a drive signal is output to connect the parallel oil passage 64 to the check valve 48. In FIG. 3, since the stroke signal SS is ON, the electromagnetic switching valve 68 is also in the operating state.
That is, a state in which the parallel oil passage 64 is connected to the check valve 48 is shown. The same applies to other drawings thereafter.

In the pressure equalizing device 60 of this embodiment, the stroke signal SS of the press stroke detecting means 54 is
At the time of non-press working of F, the cylinder oil pressure P is set to a predetermined initial oil pressure (P ₁ -P _S ) according to the first oil pressure P ₁ adjusted by the first pressure reducing valve 62. , The pistons of the hydraulic cylinders 32 involved are driven in, and a neutralized state is obtained. On the other hand, at the time of the press working in which the stroke signal SS of the press stroke detecting means 54 is turned on, the second hydraulic pressure P ₂ regulated by the second pressure reducing valve 66 is made to act on the check valve 48, and the above-described embodiment is performed. Similarly to the above, even if the cylinder oil pressure P becomes lower than the initial oil pressure (P ₁ -P _S ), the operating oil flows into the hydraulic cylinder 32 through the check valve 48 unless the oil pressure becomes lower than the oil pressure (P ₂ -P _S ). No pumping phenomenon occurs. Also in this embodiment, the check valve 4
Since the oil pressure on the side opposite to the hydraulic cylinder 32 side with respect to the oil pressure 8 is reduced, pumping can be more reliably prevented. Further, since the second pressure reducing valve 66 and the electromagnetic switching valve 68 for preventing pumping are disposed closer to the hydraulic pressure source 44 than the check valve 48, a large hydraulic pressure such as the hydraulic cylinder 32 acts. As compared with a conventional device in which an electromagnetic on-off valve is disposed between the hydraulic cylinder 32 and the check valve 48, excellent durability as a whole is obtained.

As described above, also in this embodiment, the same effect as in the first embodiment can be obtained in that the pumping can be satisfactorily prevented without impairing the durability of the apparatus. Since the pressure is changed by using the valves 62 and 66, the hydraulic circuit becomes somewhat complicated as compared with the case where the expensive proportional electromagnetic relief pressure reducing valve 46 is used as in the first embodiment. Although the device is configured inexpensively. The controller 70 also outputs O
Since it is only necessary to switch the electromagnetic switching valve 68 in accordance with N and OFF, there is no need for storage means for storing the first hydraulic pressure P ₁ and the second hydraulic pressure P _2, and the apparatus is also inexpensive in this respect.

Further, since it is only necessary to switch the oil passage by the electromagnetic switching valve 68, it is possible to quickly change the hydraulic pressure and obtain excellent responsiveness. Even if the electromagnetic switching valve 68 is switched immediately before colliding with the mold 30, the hydraulic pressure acting on the check valve 48 is immediately reduced, and pumping is prevented well. Since the response is fast, the second hydraulic pressure P _2, that is, the second hydraulic pressure P 2
The discharge pressure of the pressure reducing valve 66 can be set to a sufficiently low oil pressure, and pumping can be prevented more reliably.
The stroke signal SS is changed immediately to the first hydraulic pressure P ₁ even when a OFF, can afford the adjustment time for adjusting the initial hydraulic pressure by the first pressure P _1. In contrast,
When the hydraulic pressure is changed by the proportional electromagnetic relief pressure reducing valve 46, it takes time until the hydraulic pressure actually changes, and in order to reliably prevent pumping, the delay time is taken into consideration by the press stroke detecting means 54 in consideration of the delay time. it is necessary to set the stroke detection position on the upper side, together with the adjustment time for adjusting the initial hydraulic pressure is shortened by the first hydraulic pressure P _1, a second hydraulic pressure P ₂ is not able to too low.

This embodiment is an example of the third aspect of the present invention, in which the first pressure reducing valve 62 constitutes an oil supply means together with the hydraulic pressure source 44, the parallel oil passage 64 and the second pressure reducing valve 66 as the pressure reducing means. This constitutes an inflow prevention means. Further, an electromagnetic switching valve 68 as a switching means, a controller 70
The press stroke detecting means 54 constitutes an inflow prevention control means.

The pressure equalizing device 74 of FIG. 4 is different from the pressure equalizing device 60 of FIG. 3 in that the second pressure reducing valve 66 is connected between the first pressure reducing valve 62 and the hydraulic pressure source 44 by the first pressure reducing valve 62. A parallel oil passage 76 provided in series and provided in parallel with the second pressure reducing valve 66.
An electromagnetic opening / closing valve 78 is disposed in the controller, and the controller 70 controls opening and closing of the electromagnetic opening / closing valve 78. The controller 70 determines that the stroke signal SS
In the case of the FF, the electromagnetic on-off valve 78 is opened to connect the parallel oil passage 76, and the hydraulic oil supplied from the hydraulic pressure source 44 is directly supplied to the first oil supply.
On the other hand, when the stroke signal SS is ON, the electromagnetic on-off valve 78 is closed as shown in FIG.
6 is shut off, and the hydraulic oil reduced to the second hydraulic pressure P ₂ by the second pressure reducing valve 66 is supplied to the first pressure reducing valve 62.

Also in the pressure equalizing device 74 of this embodiment, the stroke signal SS of the press stroke detecting means 54 is
At the time of non-press working of F, the cylinder oil pressure P is set to a predetermined initial oil pressure (P ₁ -P _S ) according to the first oil pressure P ₁ adjusted by the first pressure reducing valve 62. , The pistons of the hydraulic cylinders 32 involved are driven in, and a neutralized state is obtained. On the other hand, at the time of press working in which the stroke signal SS of the press stroke detecting means 54 is turned ON, the second pressure reducing valve 66 functions and the operating oil reduced to the second oil pressure P ₂ is supplied to the first pressure reducing valve 62. Therefore, even if the cylinder oil pressure P becomes lower than the initial oil pressure (P ₁ −P _S ), the occurrence of a pumping phenomenon in which the hydraulic oil flows into the hydraulic cylinder 32 through the check valve 48 is prevented. Also, since the second pressure reducing valve 66 for preventing pumping is disposed closer to the hydraulic pressure source 44 than the check valve 48, the hydraulic cylinder 32
A large hydraulic pressure does not act on the side, and superior durability can be obtained as a whole device as compared with a conventional device in which an electromagnetic on-off valve is disposed between the hydraulic cylinder 32 and the check valve 48.

As described above, also in the present embodiment, pumping can be favorably prevented without impairing the durability of the apparatus, similarly to the above embodiments. Also, inexpensive pressure reducing valves 62, 66
Is used to change the pressure, so that the expensive proportional electromagnetic relief pressure reducing valve 46 as in the first embodiment is used.
As compared with the case of using a hydraulic circuit, although the hydraulic circuit is somewhat complicated, the device can be configured at low cost and excellent responsiveness can be obtained. The controller 70 also outputs O
Since it is only necessary to open and close the electromagnetic on-off valve 78 in accordance with N and OFF, there is no need for storage means for storing the first hydraulic pressure P ₁ and the second hydraulic pressure P _2, and the apparatus is also inexpensive in this respect.

This embodiment is an example of the second aspect of the present invention, in which the first pressure reducing valve 62 constitutes an oil supply means together with the hydraulic pressure source 44, and the inflow prevention means is provided by the second pressure reducing valve 66 as the pressure reducing means. It is configured. Also, the solenoid on-off valve 78,
Controller 70 and press stroke detecting means 54
This constitutes the inflow prevention control means.

The pressure equalizing device 80 in FIG. 5, the hydraulic adjusting means 82 always outputs by applying a constant supply pressure P ₀ two tone predetermined hydraulic oil supplied from the hydraulic source 44, the hydraulic adjusting means 82 Electromagnetic switching valve 8 disposed between the valve and the check valve 48
4 is provided. The hydraulic pressure adjusting means 82 includes, for example, the proportional electromagnetic relief pressure reducing valve 46 and the first pressure reducing valve 6.
2, or on-off valve, a relief valve is configured by an oil pressure sensor, the paper pressure P ₀ is set in the same manner as the first hydraulic P _1. When the stroke signal SS is OFF, the controller 70 that switches and controls the electromagnetic switching valve 84 causes the electromagnetic switching valve 84 to communicate the oil supply oil passage 42 and adjusts the supply oil pressure P ₀ to the supply oil pressure P ₀ by the oil pressure adjusting means 82. While the oil is applied to the check valve 48, when the stroke signal SS is ON, the oil supply passage 42 is shut off as shown in the figure, and the hydraulic oil on the check valve 48 side with respect to the electromagnetic switching valve 84 is drained. .

Also in the pressure equalizing device 80 of this embodiment, the stroke signal SS of the press stroke detecting means 54 is
At the time of non-press working of F, the cylinder oil pressure P is set to a predetermined initial oil pressure (P ₀ −P _S ) in accordance with the supply oil pressure P ₀ adjusted by the oil pressure adjusting means 82, thereby participating in press working at the time of press working. The pistons of the hydraulic cylinders 32 to be driven are respectively driven in, and a pressure equalized state in which the pistons are in a neutral state is obtained. On the other hand, at the time of press working in which the stroke signal SS of the press stroke detecting means 54 is turned on, the electromagnetic switching valve 84 is switched so that the oil passage between the check valve 48 and the hydraulic pressure adjusting means 82 is shut off, and Since the hydraulic oil on the valve 48 side is drained, even if the cylinder oil pressure P becomes lower than the initial oil pressure (P ₀ −P _S ), the pumping phenomenon in which the hydraulic oil flows into the hydraulic cylinder 32 through the check valve 48 There is no danger of occurrence. In this embodiment, since the hydraulic oil on the check valve 48 side is drained, pumping is reliably prevented. Also, an electromagnetic switching valve 84 for preventing pumping
Is disposed between the check valve 48 and the hydraulic pressure adjusting means 82, so that a large hydraulic pressure does not act on the hydraulic cylinder 32 side, and the electromagnetic force is applied between the hydraulic cylinder 32 and the check valve 48. As compared with a conventional device having an on-off valve, excellent durability can be obtained as a whole device.

As described above, also in the present embodiment, pumping can be favorably prevented without impairing the durability of the apparatus as in the above-described embodiments. Further, since it is only necessary to switch the oil passage by the electromagnetic switching valve 84, the apparatus can be configured at a lower cost as compared with the case of using the expensive proportional electromagnetic relief pressure reducing valve 46 as in the first embodiment. Since the controller 70 only needs to switch the electromagnetic switching valve 84 in accordance with ON / OFF of the stroke signal SS, storage means for storing the first hydraulic pressure P ₁ and the second hydraulic pressure P ₂ is not required.
Also in this respect, the apparatus becomes inexpensive. Further, when the oil passage is switched by the electromagnetic switching valve 84, the hydraulic pressure in the vicinity of the check valve 48 (on the side opposite to the hydraulic cylinder 32) is quickly changed, so that the pressure equalizing device 60 of FIG. responsiveness is obtained and can afford the adjustment time for adjusting the initial hydraulic pressure in oil supply pressure P _0.

This embodiment is an example of the second aspect of the present invention, in which the oil pressure adjusting means 82 constitutes an oil supply means together with the oil pressure source 44, and the electromagnetic switching valve 84 as the pressure reducing means corresponds to the inflow prevention means. . The controller 70 and the press stroke detecting means 54 constitute an inflow prevention control means.

The pressure equalizing device 90 shown in FIG.
A check valve 92 having a variable spring pressure (preload) is disposed in a refueling oil passage 42 between the hydraulic cylinder 32 and the hydraulic cylinder 32, and the spring pressure of the check valve 92 is changed by a controller 94. The check valve 92 is configured, for example, as shown in FIG. In FIG. 7, the housing 96 is provided with a first port 98 connected to the oil passage on the hydraulic pressure adjusting means 82 side and a second port 100 connected to the oil passage on the hydraulic cylinder 32 side, and as the urging means. The valve body 104 is urged to the first port 98 by the compression coil spring 102. Therefore, the first port from the second port 100 side
The flow of hydraulic oil to the port 98 side is blocked while the first
The flow of hydraulic oil from the port 98 side to the second port 100 side is allowed by pushing down the valve body 104 against the spring force of the compression coil spring 102, Assuming that the hydraulic pressure drop on the first port 98 side is the same as the supply hydraulic pressure P ₀ and the hydraulic pressure drop amount based on the spring force of the compression coil spring 102 is the same as the hydraulic pressure drop amount P _S , the second port 100
, The cylinder hydraulic pressure P is balanced by (P ₀ −P _S ), and when the cylinder oil pressure P becomes lower than the oil pressure (P ₀ −P _S ), the hydraulic cylinder 32 passes through the check valve 92.
Hydraulic oil flows into the side.

A spring support 106 supporting the rear end of the compression coil spring 102 is movable in the moving direction of the valve element 104, that is, in the left-right direction in the figure, and an electric motor 108 functioning as an urging force increasing means is rotationally driven. As a result, it can be made to approach the valve body 104 by a certain dimension via the feed screw 110. FIG. 7 shows the spring receiver 10.
6 is held at the first position separated from the valve element 104, and can be reciprocated between the second position moved rightward by a certain distance from the first position, and held at the first position. In this case, the hydraulic pressure drop amount is the aforementioned P _S. When the spring receiver 106 moves to the second position and approaches the valve element 104, the spring force of the compression coil spring 102 increases, and the amount of hydraulic pressure drop increases with the increase of the spring force. When the amount and [Delta] P _S cylinder pressure P
Is balanced by (P ₀ −P _S −ΔP _S ), and when the cylinder oil pressure P becomes lower than the oil pressure (P ₀ −P _S −ΔP _S ), it passes through the check valve 92 to the hydraulic cylinder 32 side. Hydraulic oil flows into the The controller 94 holds the spring receiver 106 at the first position when the stroke signal SS is OFF, and holds the spring receiver 106 at the second position when the stroke signal SS is ON. The motor 108 is driven by a stroke signal SS
Is switched in the opposite direction to each other, for example, for a predetermined period of time, or for a predetermined number of rotations, in response to ON and OFF of the signal.

In such a pressure equalizing device 90, the press
The stroke signal SS of the stroke detection means 54 is OF
During non-press working of F, hydraulic pressure drop by check valve 92
Is P _SThe supply hydraulic pressure adjusted by the hydraulic adjustment means 82
P₀From hydraulic pressure P_SInitial oil pressure (P₀−
P_S), The cylinder oil pressure P is adjusted, and the
During processing, the hydraulic cylinder 32
Equalized pressure state where each stone is driven into neutral state
Is obtained. On the other hand, the press stroke detecting means 54
When the troke signal SS is ON, press the check valve 9
The second spring receiver 106 is moved to the second position.
Reduces the hydraulic pressure drop by ΔP_SSupply pressure P
₀From the hydraulic pressure drop (P_S+ ΔP_S) Minus the hydraulic pressure (P₀
−P_S−ΔP_SIf the cylinder oil pressure P is lower than
In this case, the hydraulic oil flows into the hydraulic cylinder 32 side. Paraphrase
If the cylinder oil pressure at the time of pressure adjustment before press working (initial oil
Pressure) P = P₀−P_SΔP increase in hydraulic pressure drop_SIs
If the cylinder oil pressure P does not drop further, the check valve 92
Hydraulic oil does not flow into the hydraulic cylinder 32 side
Therefore, the cylinder oil pressure P is temporarily
Initial hydraulic pressure (P₀−P_S) Even lower
Increase in pressure drop ΔP_SAs long as the oil pressure does not drop
The pumping phenomenon in which hydraulic oil flows into the pressure cylinder 32 is
Does not happen.

In this embodiment, since the amount of hydraulic pressure drop by the check valve 92 is increased to prevent pumping, an electromagnetic on-off valve is provided closer to the hydraulic cylinder 32 than the check valve 92. The durability is improved in comparison. The check valve 92 has a simpler structure than a solenoid on-off valve and has sufficient durability against high pressure.
Even if a high hydraulic pressure acts on the check valve 92, excellent durability can be obtained as a whole of the device.

As described above, also in the present embodiment, pumping can be favorably prevented without impairing the durability of the apparatus, similarly to the above embodiments. Further, the apparatus is configured at a lower cost as compared with the case where the hydraulic pressure is reduced by the proportional electromagnetic relief pressure reducing valve 46 or the second pressure reducing valve 66 to prevent pumping.

This embodiment is an example of the fourth aspect of the present invention, in which the oil supply means is constituted by the oil pressure adjusting means 82 and the oil pressure source 44, and is provided on the check valve 92 to move the spring receiver 106. The motor 108 corresponds to a hydraulic pressure drop increasing unit. Further, the controller 94 and the press stroke detecting means 54 constitute a hydraulic pressure drop controlling means.

The equalizing device 114 shown in FIG.
The check valve 48 and a spring 116 having a greater spring force than the spring 50 of the check valve 48 urges the valve body to the valve closing side in the oil supply oil passage 42 between the hydraulic control device 2 and the hydraulic pressure adjusting means 82. A check valve 118 whose hydraulic pressure drop is larger than the check valve 48 by ΔP _S is disposed in parallel, and the oil supply passage 42 b in the portion where the check valve 48 is provided, and the check valve 118
The connection state between the parallel oil passage 120 provided with the oil pressure adjusting means 82 and the parallel oil passage 120 is switched by the electromagnetic switching valve 122. The controller 70 that controls the electromagnetic switching valve 122 stops the output of the drive signal when the stroke signal SS is OFF, connects the refueling oil passage 42b to the hydraulic pressure adjusting means 82, and when the stroke signal SS is ON, Outputs a drive signal to connect the parallel oil passage 120 to the hydraulic pressure adjusting means 82 as shown in the figure.

In this embodiment, the press stroke detection
Non-pressing operation when the stroke signal SS of the informing means 54 is OFF
At the time of construction, supply hydraulic pressure P to check valve 48₀Hydraulic oil
Supply hydraulic pressure P₀From hydraulic pressure P_SInitial subtracted
Hydraulic pressure (P₀−P_S), The cylinder oil pressure P is adjusted.
Hydraulic presses involved in press working during press working.
Pistons 32 are driven into neutral state
A uniform pressure condition is obtained. Meanwhile, press stroke detection
At the time of press working when the stroke signal SS of the means 54 is ON
Means that the electromagnetic switching valve 122 is switched and the supply hydraulic pressure P₀Work
The hydraulic fluid is caused to act on the check valve 118,
The amount of descent is ΔP_SOnly increased. For this, press
The cylinder oil pressure P is changed to the initial oil pressure (P₀
−P_S) Even if it becomes lower, the above hydraulic pressure drop amount further increases
Minute ΔP_SOnly low oil pressure (P₀−P _S−ΔP_S) Lower
Hydraulic fluid flows into the hydraulic cylinder 32 unless it
No pumping phenomenon occurs. In this embodiment, the check
A check valve 118 with a large hydraulic pressure drop is provided in parallel with the valve 48
These are switched by the electromagnetic switching valve 122 to reduce the hydraulic pressure drop amount.
To prevent pumping by changing
Therefore, as in the embodiment of FIG.
And excellent durability can be obtained.

As described above, also in the present embodiment, pumping can be favorably prevented without impairing the durability of the apparatus, similarly to the above-described embodiments. Further, the apparatus is configured at a lower cost as compared with the case where the hydraulic pressure is reduced by the proportional electromagnetic relief pressure reducing valve 46 or the second pressure reducing valve 66 to prevent pumping. Furthermore, in the present embodiment, excellent responsiveness is obtained because it is only necessary to switch between the check valves 48 and 118 by the electromagnetic switching valve 122, so that the adjustment time for adjusting the initial oil pressure can be afforded. The same effect as the embodiment of FIG. 3 can be obtained, for example, by adopting a hydraulic pressure drop amount that is sufficiently large to prevent pumping more reliably. That is, the spring receiver 106 is moved as in the embodiment of FIG.
Is changed, it takes time until the hydraulic pressure drop actually changes, and in order to surely prevent pumping, the delay time is taken into consideration in order to reduce the press stroke detecting means 54.
It is necessary to set the stroke detection position on the upper side, and the adjustment time for adjusting the initial oil pressure is shortened,
It is difficult to greatly change the amount of hydraulic pressure drop.

This embodiment is an example of the fourth aspect of the present invention, in which the oil supply means is constituted by the oil pressure adjusting means 82 and the oil pressure source 44, and the check valve 118 corresponds to the oil pressure drop increasing means. Further, the electromagnetic switching valve 122 and the controller 7
0 and the press stroke detecting means 54 constitute a hydraulic pressure drop controlling means.

In the pressure equalizing device 130 shown in FIG. 9, a check valve 132 is arranged in series with the check valve 48 in the oil supply passage 42 between the check valve 48 and the hydraulic pressure adjusting means 82, and the check valve is provided. Valve 13
An electromagnetic on-off valve 136 is provided in a parallel oil passage 134 provided in parallel with the
6 is controlled to open and close. When the stroke signal SS is OFF, the controller 70 opens the electromagnetic on-off valve 136 to communicate the parallel oil passage 134, and supplies the hydraulic oil of the supply oil pressure P ₀ supplied from the oil pressure adjusting means 82 directly to the check valve 48. On the other hand, when the stroke signal SS is ON, the solenoid on-off valve 136 is closed to shut off the parallel oil passage 134 as shown in the figure, so that hydraulic oil is supplied to the check valve 48 through the check valve 132. I do. The check valve 132 is provided with a spring 138 as an urging means for urging the valve body to the valve closing side similarly to the check valve 48, and causes a hydraulic pressure drop according to the spring force. This hydraulic pressure drop amount is ΔP
_S , in the state where the check valves 48 and 132 are connected in series, that is, in the state where the solenoid on-off valve 136 is closed and the parallel oil passage 134 is shut off, the total hydraulic pressure drop amount is (P _S + ΔP _S). ), And when the cylinder oil pressure P becomes lower than the oil pressure (P ₀ −P _S −ΔP _S ), the hydraulic oil flows into the hydraulic cylinder 32 through the check valves 48 and 132.

In the present embodiment, when the stroke signal SS of the press stroke detecting means 54 is not pressed and the stroke signal SS is OFF, the hydraulic oil of the supply hydraulic pressure P ₀ is supplied to the check valve 48 via the electromagnetic switching valve 136. pressurized cylinder pressure P is regulated from oil supply pressure P ₀ to the hydraulic drop P _S subtraction with initial pressure (P ₀ -P _S), the piston of the hydraulic cylinder 32 involved in press working forced each Thus when pressing And a pressure equalized state in which the pressure becomes neutral. On the other hand, the stroke signal S of the press stroke detecting means 54
At the time of press working in which S is ON, the solenoid on-off valve 136 is closed and the parallel oil passage 134 is shut off.
Hydraulic drop amount of the whole by hydraulic drop amount [Delta] P _S increases the.
For this reason, the cylinder oil pressure P
There initial oil pressure (P ₀ -P _S) also becomes lower than the further the hydraulic drop amount increment [Delta] P _S only low oil pressure (P ₀ -P _S -
Unless it becomes lower than ΔP _S ), the pumping phenomenon that the hydraulic oil flows into the hydraulic cylinder 32 side does not occur. Also,
In this embodiment, since the check valve 132 and the electromagnetic on-off valve 136 are disposed between the check valve 48 and the hydraulic pressure adjusting means 82 to change the hydraulic pressure drop, the check valve 132 Such a large hydraulic pressure does not act, and superior durability can be obtained as a whole device as compared with a conventional device in which an electromagnetic on-off valve is arranged between the hydraulic cylinder 32 and the check valve 48.

As described above, in this embodiment as well, pumping can be favorably prevented without impairing the durability of the apparatus, as in the above embodiments. In addition, compared to the case where the hydraulic pressure is reduced by the proportional electromagnetic relief pressure-reducing valve 46 or the second pressure-reducing valve 66 to prevent pumping, the apparatus is constructed at a lower cost and compared with the embodiment of FIG. And excellent responsiveness can be obtained.

This embodiment is an example of the fourth aspect of the invention, in which the oil supply means is constituted by the oil pressure adjusting means 82 and the oil pressure source 44, and the check valve 132 corresponds to the oil pressure drop increasing means. In addition, the solenoid on-off valve 136, the controller 7
0 and the press stroke detecting means 54 constitute a hydraulic pressure drop controlling means. This embodiment can be regarded as an example of the invention described in claim 1. In this case, the check valve 132 corresponds to the inflow prevention means, and the electromagnetic on-off valve 136, the controller 70 and the press stroke The detecting means 54 corresponds to the inflow prevention control means.

While some embodiments of the present invention have been described in detail with reference to the drawings, the present invention can be embodied in other forms.

For example, in the above embodiment, the hydraulic pressure is reduced or the hydraulic pressure drop amount is increased by turning on the stroke signal SS of the single press stroke detecting means 54, and is restored by turning off the stroke signal SS. However, the timing for changing the hydraulic pressure and the amount of hydraulic pressure drop, such as providing a separate press stroke detecting means for detecting the bottom dead center of the press stroke and restoring it at another timing such as the bottom dead center, is not provided. It can be changed as appropriate.

Although the press stroke detecting means 54 of the above embodiment detects the position of the slide plate 20, the press stroke is detected by the movement of another operating member such as a crank angle or the like, The press stroke can be detected based on the elapsed time from a reference position such as a point.

In the above-described embodiment, the check valve 48 includes the spring 50 for urging the valve body toward the valve closing side. However, a check valve without such urging means may be employed. It is possible.

In the embodiment of FIG. 3, the first pressure reducing valve 6
2 is disposed in parallel with the second pressure reducing valve 66, but the first pressure reducing valve 62 may be disposed closer to the hydraulic power source 44 than the parallel circuit portion. The electromagnetic switching valve 68 may be provided at a connection portion closer to the hydraulic power source 44 than the pressure reducing valves 62 and 66.

In the embodiment shown in FIG.
Although the electromagnetic switching valve 84 for draining the hydraulic oil on the check valve 48 side when shutting off is used, an electromagnetic opening / closing valve that merely communicates and shuts off the oil supply passage 42 is provided instead of the electromagnetic switching valve 84. Is also possible. In that case, an embodiment of the invention described in claim 1 is provided.

The check valve 92 shown in FIG. 7 is designed to change the preload, that is, the hydraulic pressure drop by moving the spring receiver 106 by the electric motor 108 and the feed screw 110. For example, the spring receiver 106 is moved by using such a means, or the valve body 104 is directly urged by air pressure and the air pressure is changed.
Various other biasing means may be employed.

In the embodiment shown in FIG.
Although a single check valve 118 is provided at 0, a plurality of check valves each provided with an urging means may be arranged in series. In the embodiment of FIG. 9, one or more check valves can be additionally provided in series with the check valve 132.

In the above embodiment, the pressure equalizing device for equalizing the wrinkle holding load of the single action type press machine has been described. However, the wrinkle holding load (outer load) of the double action type press machine is equalized. Pressure equalizer,
The present invention can be similarly applied to a pressure equalizing device for equalizing other loads such as a forming load.

Although not specifically exemplified, the present invention can be embodied with various modifications and improvements based on the knowledge of those skilled in the art.

[Brief description of the drawings]

FIG. 1 is a configuration diagram illustrating an embodiment of a pressure equalizing device for a press machine based on the invention described in claim 1;

FIG. 2 is a flowchart illustrating an operation of a controller in the pressure equalizing device of FIG. 1;

FIG. 3 is a configuration diagram for explaining another embodiment of a pressure equalizing device for a press machine based on the invention described in claim 1;

FIG. 4 is a configuration diagram for explaining still another embodiment of a pressure equalizing device for a press machine based on the first aspect of the present invention.

FIG. 5 is a configuration diagram for explaining still another embodiment of a pressure equalizing device for a press machine based on the first aspect of the present invention.

FIG. 6 is a configuration diagram illustrating an embodiment of a pressure equalizing device for a press machine based on the invention described in claim 4.

FIG. 7 is a cross-sectional view illustrating a basic structure of a check valve in the pressure equalizing device of FIG.

FIG. 8 is a configuration diagram illustrating another embodiment of a pressure equalizing device for a press machine based on the invention described in claim 4.

FIG. 9 is a configuration diagram illustrating a pressure equalizing device of a press machine according to an embodiment of the present invention.

[Explanation of symbols]

10: Press machine 32: Hydraulic cylinder 40, 60, 74, 80, 90, 114, 130: Pressure equalizer 42, 42a, 42b: Oil supply passage 44: Hydraulic source (oil supply means) 46: Proportional electromagnetic relief pressure reducing valve (Lubricating means, inflow preventing means, depressurizing means) 48, 92: check valve 52: controller (inflow preventing control means) 54: press stroke detecting means (inflow preventing controlling means,
Hydraulic descent control means) 62: first pressure reducing valve (oil supply means) 64: parallel oil passage (inflow prevention means) 66: second pressure reduction valve (inflow prevention means, pressure reducing means) 68: electromagnetic switching valve (inflow prevention control means, Switching means) 70: Controller (inflow prevention control means, hydraulic pressure drop control means) 78: Electromagnetic on-off valve (inflow prevention control means) 82: Hydraulic pressure adjusting means (oil supply means) 84: Electromagnetic switching valve (inflow prevention means, pressure reducing means) 94: Controller (Hydraulic descent control means) 108: Electric motor (Hydraulic descent increase means) 118: Check valve (Hydraulic descent increase means) 122: Electromagnetic switching valve (Hydraulic descent control means) 132: Check valve (Inflow prevention means) 136: solenoid on-off valve (inflow prevention control means, hydraulic pressure drop control means) P: cylinder oil pressure P ₀ , P ₁ : supply oil pressure ΔP _S : increase in oil pressure drop

Claims (4)

(57) [Claims] An oil chamber is connected to a plurality of hydraulic cylinders connected to each other via an oil supply passage, and
An oil supply means for supplying hydraulic oil to the hydraulic cylinder at a predetermined oil supply pressure; and an oil supply means disposed in the oil supply oil passage, allowing a flow of the hydraulic oil from the oil supply means side to the hydraulic cylinder side and a flow in the opposite direction. And a check valve for preventing the hydraulic pressure in the hydraulic cylinder is set to a predetermined initial oil pressure equal to or less than the supply hydraulic pressure prior to press working, and the pistons of the plurality of hydraulic cylinders are driven in at the time of press working. In a pressure equalizing device of a press machine that distributes a load evenly through the plurality of hydraulic cylinders by being in a neutral state, the pressure equalizer is disposed closer to the refueling means than the check valve, and the cylinder oil pressure is Inflow prevention means for preventing the hydraulic oil from flowing from the oil supply means side through the check valve even if the oil pressure drops below the initial oil pressure, and the function of the inflow prevention means is stopped before press working Then,
A pressure equalizing apparatus for a press machine, wherein the cylinder pressure is adjusted to the initial oil pressure, and at least at the initial stage of the press working, there is provided an inflow prevention control means for operating the inflow prevention means. 2. A pressure equalizing device for a press machine according to claim 1, wherein said inflow prevention means has a pressure reducing means for lowering the oil pressure on the oil supply means side than said check valve. 3. The inflow prevention means includes: a parallel oil passage connected in parallel to the oil supply oil passage; and a pressure reducing means provided in the parallel oil passage to reduce the pressure to a lower oil pressure than the supply oil pressure. The inflow prevention control means has switching means for switching between a state in which hydraulic oil is supplied to the check valve from the oil supply oil path and a state in which hydraulic oil is supplied from the parallel oil path to the check valve. 2. The press machine according to claim 1, wherein the control means controls the switching means such that hydraulic oil is supplied from the oil supply passage while hydraulic oil is supplied from the parallel oil passage at the beginning of press working. Equalizing device. 4. An oil chamber is connected to a plurality of hydraulic cylinders connected to each other through an oil supply passage, and
An oil supply means for supplying hydraulic oil to the hydraulic cylinder at a predetermined oil supply pressure; and an oil supply means disposed in the oil supply oil passage, allowing a flow of the hydraulic oil from the oil supply means side to the hydraulic cylinder side and a flow in the opposite direction. A check valve for preventing the hydraulic pressure from being supplied to the cylinder, and prior to press working, the cylinder oil pressure in the hydraulic cylinder is set to a predetermined initial oil pressure equal to or less than the supply hydraulic pressure. In a pressure equalizing device for a press machine that distributes a load evenly through the plurality of hydraulic cylinders by being in the neutral state, a pressure adjusting device that adjusts a hydraulic pressure drop amount by the check valve to an initial hydraulic pressure of the cylinder hydraulic pressure. Means for increasing the hydraulic pressure drop which is greater than when the pressure is applied; and increasing the hydraulic pressure drop by the hydraulic pressure drop increasing means before press working, and the cylinder oil pressure is reduced to the initial oil pressure. Pressure is allowing it, pressure equalization apparatus of a press machine, characterized in that it comprises a hydraulic drop control means for increasing the pressure drop at least pressing initial by the hydraulic drop increasing means.