JPH02112900A - Pneumatic type die cushion device - Google Patents

Abstract

PURPOSE:To eliminate the need for a large-capacity buffer tank, compressor, exhaust valve, etc., by communicating a lower chamber and upper chamber which pinches a piston of a cylinder with two air flow passages, mounting stop valves respectively thereto and opening and closing the valves under specific conditions. CONSTITUTION:The stop valve 20 having a check valve function exists in the 1st air communicating passage 10 which communicates the upper chamber 1U and lower chamber 1L of the piston 2 of the cylinder 1. This valve opens when the difference between the pressure PL in the lower chamber and the pressure PU in the upper chamber attains a set pressure value or above. The stop valve 31 of the 2nd air flow passage 30 communicates the upper chamber IU and the lower chamber 1L at the proper time during the ascending course of the piston 2. A controller 55 compares the pressure PU in the upper chamber detected by a pressure detector 33 and the set value of a setter 56 and opens the stop valve 31 when both the pressures are equaled. The cushion performance is regulated by controlling the differential pressure of the upper and lower chambers with the 1st stop valve 20 and, therefore, a large-sized buffer tank is not needed.

Description

[Detailed description of the invention] [Industrial application field] The present invention relates to a pneumatic die cushion device for a press.

Specifically, it is formed from a closed cylinder device, and the die cushion capacity during press operation is variable.

[Conventional technology] FIG. 4 shows a conventional pneumatic die cushion device.

In the figure, 1 is an air syringe which is separated by a piston 2 into an upper chamber IU and a lower chamber IL.

The upper chamber IU is open to the atmosphere through an opening 5. 4 is a wear plate fixed to the -E end of the piston rod 3 and receives an action pin (not shown). Further, 6 is a buffer tank which is communicated with the lower chamber IL via a connecting pipe 7.

In the die cushion device having such a configuration, the upper chamber IU is open to the atmosphere, so the upper chamber internal pressure Pu is constant and equal to atmospheric pressure. Therefore, the die cushion capacity [Pa can be found from the lower chamber pressure P[ and the cross-sectional area A1 of the piston 2 (F=P
L・AI). However, as the piston 2 descends, that is, as the volume of the lower chamber IL decreases, the lower chamber pressure PL increases, so the die cushioning capacity increases. On the other hand, the die cushion capacity, that is, the necessary wrinkle holding force (F), is determined based on the material of the material, etc., and therefore, excessive capacity is inconvenient.

Conventionally, in order to increase the apparent volume of the lower chamber IL and suppress excessive fluctuations in the die cushion capacity F, the lower chamber IL has a volume that is 5 to 8 times the volume of the cylinder 1. It is common that a buffer tank 6 is provided.

Therefore, as shown by the two-dot chain line in FIG. 3, the initial pressure PLS necessary to obtain the die cushioning capacity (required wrinkle pressing force) Fa must be established in the lower chamber IL and the buffer tank 6. For example, piston 2 is at the upper limit U1. , , , the necessary wrinkle pressing force Fa is established at the same time as the downward movement starts. Thereafter, as shown by the dashed line in the same figure, it gradually increases at a constant ratio based on the volume ratio of the cylinder 1 and the buffer tank 6. The die cushion capacity when piston 2 reaches the lower limit LL is Fae.

[Problems to be Solved by the Invention] As described above, the conventional die cushion device introduces a large-capacity buffer tank 6 to increase the apparent volume of the lower chamber IL, and attempts to keep the necessary wrinkle pressing force constant. The configuration was as follows.

Therefore, in today's world where presses are becoming larger, automation as seen in transfer presses, and higher quality and productivity improvements are required, the following problems have become unacceptable.

- The installation space for the buffer tank 6 is large, which is not only uneconomical, but also increases the size of the press and limits the layout of other functional items.

In particular, the influence is excessive in transfer presses and the like that have many molds.

■ It took a long time to establish the initial pressure PLS or adjust the die cushion capacity, resulting in a situation where the press could not operate even though other initial conditions had been established in a short time. . On the other hand, in order to establish a rapid initial pressure PLS, a high-pressure, large-capacity compressor must be installed, which is even more disadvantageous in terms of equipment economy and installation space.

Furthermore, when performing adjustment work to reduce the die cushion capacity, it is necessary to provide a large, rapidly actuated exhaust valve, which also imposes a heavy economic burden.

Furthermore, since a large amount of high-pressure air is released into the atmosphere each time the system is adjusted, it is also disadvantageous in terms of operational economy.

(2) Furthermore, even if the above-mentioned sacrifices (2) and (3) are accepted, it is impossible to make the capacity of the buffer tank 6 infinitely large. Therefore, as the piston 2 descends, the die cushioning capacity increases to varying degrees.

However, in today's world where ultimate high quality and cost reduction are required, in many product processing processes, it is difficult to tolerate fluctuations in the die cushion capacity, which increase proportionally and uniquely from the upper limit UL to the lower limit LL of the piston 2. This is no longer the case.

On the other hand, materials for press processing have become more complex and precise from the viewpoints of cost reduction and final product quality6. If the die cushion capacity cannot be changed accordingly, there are many cases where defective products are produced. In other words, if the die cushion capacity can be changed and adjusted during press operation, a wide variety of products can be processed with high efficiency, and dramatic cost reductions and high quality processing can be achieved. but,
It was thought that this could not be achieved with a pneumatic die cushion device.

The object of the present invention is to provide a simple structure and easy handling that can eliminate conventional large-capacity buffer tanks, high-pressure large compressors, rapid large-scale exhaust valves, etc., and change and adjust die cushion capacity during press operations. The purpose of the present invention is to provide a pneumatic die cushion device that is small and lightweight at low cost.

[Means for Solving the Problems 1] The present invention is formed from a closed cylinder device, whereas the conventional device is composed of a cylinder device that is open to the atmosphere, and the die cushioning capacity of the closed cylinder device is Tachikawa is based on the principle that the pressure is determined by the differential pressure between the pressure and the pressure in the upper chamber, and the die cushion capacity can be adjusted by communicating the lower chamber and upper chamber and controlling the differential pressure during press operation. .

Specifically, a lower chamber and an upper chamber sandwiching the piston of the cylinder are communicated with each other through a first air flow path having a first on-off valve and a second air flow path having a second on-off valve, and The first on-off valve is formed to open when the pressure difference between the lower chamber pressure and the upper chamber pressure exceeds a set differential pressure value input from the differential pressure value setting means, and the second on-off valve is An opening/closing control means for controlling opening/closing timely during the piston rising process is provided, and a capability storage means for storing a plurality of capability diagrams and a selection switching means for selecting one of the capability diagrams stored in the capability storage means. The die cushion capacity during press operation can be changed and adjusted by changing the set differential pressure value outputted from the differential pressure value setting means based on the capacity diagram selected by the selection switching means. do.

[Function] In the present invention having the above configuration, if the set differential pressure value output from the differential pressure value setting means is constant, when the piston descends from the upper limit due to load, the lower chamber pressure increases, and the lower chamber pressure and upper chamber pressure increase. The pressure difference between the pressure and the pressure increases rapidly, and a die cushion capacity corresponding to the set pressure difference value is established.

Furthermore, when the piston attempts to descend, the pressure difference between the two chamber pressures becomes greater than or equal to the set differential pressure value, so the first check valve
The on-off valve is opened, and the upper chamber and upper chamber are communicated. Therefore, the pressure in the lower chamber is reduced and the differential pressure falls below the set differential pressure value, and at the same time, the first on-off valve closes.

Thereafter, as the piston descends, the first on-off valve is repeatedly opened and closed, and the differential pressure between the two chamber pressures remains within the permissible range of the required creasing force (although it fluctuates within a small range), the piston The die cushioning ability can be held substantially constant until it reaches its lower limit.

Here, when one of the performance curves stored in the performance storage means is selected by the selection switching means, the set differential pressure input from the differential pressure value setting means to the first on-off valve is set. The value corresponds to the said ability diagram. If the capacity diagram is created in such a way as to gradually increase, gradually decrease, or stepwise increase/decrease during the press operation, the die cushion capacity can be automatically changed and adjusted during the press operation.

On the other hand, when the slide begins to rise, the piston rises from the lower limit toward the upper limit due to the differential pressure between the two chamber pressures. Correspondingly, the pressure in the upper chamber gradually increases, and when the pressures in both chambers become approximately equal, the opening/closing control means opens the second opening/closing valve to establish communication between the upper chamber and the upper chamber. Therefore, the pressure in the upper chamber is prevented from increasing, and the pressures in both chambers become equal.

Even in this state, the piston rises slowly as the screws 1 to 1 are pushed up due to the difference in effective area due to the presence or absence of the piston rod (cross-sectional area).

Further, since some residual pressure exists in the upper chamber, the piston reaches its upper limit without generating a large impact force.

Further, by adjusting the closing timing of the second on-off valve appropriately, it is possible to enhance the effect in the first period tongue pinking.

[Example] Hereinafter, one embodiment of the present invention will be described with reference to the drawings.

(First Embodiment) FIG. 1 is an overall configuration diagram, and FIG. 2 is a diagram for explaining the operation.

This die cushion device includes a cylinder device including a cylinder 1, a piston 2, etc., initial pressure setting means, a first air flow path 10, and a differential pressure value for controlling the first air flow path 10. Setting means, ability storage means 521 selection switching means 53, second air flow path 30, and this second air flow path 3
It is composed of opening/closing control means for controlling opening/closing of 0.

The cylinder system consists of a cylinder 1, a piston 2, a piston rod 3, etc., and is basically the same as the conventional structure shown in FIG.

Since one purpose of the present invention is to eliminate the conventional buffer tank (6), the lower chamber 1 is not provided with the connecting pipe (7), and the upper chamber IU is open. It does not have (5) and is a closed type.

Now, the initial pressure setting means is for setting the pressure in the upper chamber IL in the initial state (piston 2 or upper limit UL), and is a means for setting the pressure in the upper chamber IL in the initial state (piston 2 or upper limit UL).
A variable pressure type pressure regulating valve 16 provided in the piping 18 connecting the . It is comprised of a check valve 17 and a controller 57 that adjusts the pressure regulating valve 16 based on the set value of a pressure setting device 58.

Further, the first air flow path 10 communicates the lower chamber IL and the upper chamber IU of the cylinder 1 when the piston 2 is lowered,
It is formed of a pipe 11 connecting both IL and IU, and a first on-off valve 20 having a check valve #R function provided in the middle of this pipe 11. The cracking pressure as a check valve function is regulated by the set differential pressure value input from the differential pressure value setting means (40, 50>).

That is, it opens when the differential pressure between the lower chamber pressure P[ and the upper chamber pressure Pu reaches the set differential pressure value.

Here, the first on-off valve 20 has a hollow cylindrical main body 21.
and a cylindrical valve body 26, and is a normally closed valve.

The main body 21 has an inlet 22 connected to the pipe 11 on the tip side.
I and an outlet 220 are provided, and an inlet 23I for applying upper chamber pressure Pu via piping 11 is provided on the rear end side.

On the other hand, a spring 29 is attached to the rear #A side hollow portion 27H of the valve body 26.
is fitted, and a valve portion 27V for closing the inlet 221 is provided at the tip.

Therefore, when the lower chamber pressure P[ increases, the valve body 26 is moved to the right in FIG. are communicated.

Also, when air is released from the lower chamber IL, the lower chamber pressure PL
As the pressure decreases, the valve 20 is closed again by the biasing force of the two springs.

In this case, the cracking pressure of the first on-off valve 20 as a check valve function is determined by the biasing force of the spring 29.

By the way, the first on-off valve 20 according to the present invention has a length of 4,v to change the cracking pressure into an IR variable.For this purpose, the first opening/closing valve 20 has a length of 4.nu. Supply pressurized air. The pressurized air serving as the control signal is used to increase the cracking pressure in addition to the biasing force of the two springs. In other words, the minimum cracking pressure is established by the biasing force of the two springs, and the cracking pressure beyond that is determined by the air pressure supplied to the inlet 23C. Note that the outlet 220 and the inlet 231 are communicated with each other for balance. Further, 230 is an air opening.

Here, the differential pressure value setting means is means for setting the crab king pressure of the first on-off valve 20, and is configured to set the air pressure supplied to the inlet 23C of the first on-off valve 20. That is, it is composed of a pressure regulating valve 40 as an electro-pneumatic converter provided in a pipe 41 that communicates the inlet 23C of the valve 20 and the air a15, and a control unit 50. The control unit h50 and the like are housed in a control panel 60 together with a music controller (55) and the like.

The control unit 50 in this embodiment includes a pressure sensor 1
The lower chamber pressure P[ from 2, the upper chamber pressure PU from the pressure detector 33, and the crankshaft angle from the angle detector 13 are input, and the lower chamber pressure PI and the upper chamber pressure pH are compared and calculated. It outputs an electric signal to control the pressure regulating valve 40 so that the differential pressure equal to the capacity signal is equal to the differential pressure corresponding to the capacity signal. In other words, the club king pressure of the first on-off valve 20 is controlled by a closed loop.

This capability signal is output from the capability signal generating means 51. The ability signal generating means 51 specifies the die cushion ability of y) in relation to the stroke of the piston 2 in order to obtain the necessary wrinkle holding force during press work, and generates a plurality of ability diagrams, that is, die cushion ability. It is formed to include a capability storage means 52 that stores a capability-piston stroke curve. The performance diagram is a black kimono with curves 1 to 2 shown in FIG. 3 as an example, and it is assumed that the performance changes during the piston stroke, that is, during the press operation. In addition, in order to expand usability, the capacity is a constant curve ■
is also remembered.

The selection switching means 53 selects which curve to select from the performance diagram.

Furthermore, the capability signal generating means 51 in this embodiment is
Piston slot talk S shown in Figure 3 for convenience of use.
Up to T1, it is configured to generate a capability signal that rapidly rises to the standard capability F set by the standard capability setter 54.

Of course, a diagram specifying the range from the upper limit U to the lower limit LL and from the lower limit LL to the upper limit Ul- is stored in the capability signal generating means 51, and the capability signal generating means 51 selects the line section selected by the selection switching means 53. It may be formed so that a corresponding capability signal is output as is to the control unit 50. In this case, the reference capability setting device 54 can be omitted (see the second embodiment).

Note that the piston throat talk is a conflict specified by the crankshaft angle input from the angle detector 13. Furthermore, since the ability storage means 52 is formed from a rewritable ROM, the ability diagram can be changed, added to, or deleted as appropriate.

Next, the second air flow path 30 communicates the upper chamber IU and the lower chamber IL at a timely point during the rising process of the piston 2, and is composed of a pipe 32 and a tra valve that connects both chambers IU and IL. Second
It is formed from an on-off valve 31.

The opening/closing control means for controlling opening/closing of this second opening/closing valve 31 is as follows:
Comprised of a pressure setting device 56 and a controller 55, the controller 55 compares the upper chamber pressure pt+ detected by the pressure detector 33 with the set value of the setting device 56, and when the two become equal, excites the solenoid. It is supposed to output a signal that When the solenoid is energized, the second on-off valve 31 is opened. Further, the controller 55 is configured to control the first valve to 0FFI and close the second on-off valve 31 again when the piston 2 approaches the upper limit port.

In addition, a differential pressure setting device is provided in place of the pressure setting device 55, and the lower chamber pressure P[ is also input to the controller 56,
The opening and closing of the second on-off valve 31 may be controlled based on the differential pressure between the pressures pt and pu in both chambers.

Note that one is an exhaust valve used when manually lowering the die cushion capacity.

The present embodiment with the above configuration operates as follows.

First, the initial pressure in the upper chamber IL is set using the pressure setting device 58. Next, the piston stroke talk S is set using the reference capacity setting device 54.
A standard capacity F that should be established by T' 1 is set, and a curve (for example, ■) suitable for the product form etc. is selected for the capacity after the stroke ST1 using the selection switching means 53, and the pressure setting device 56 The upper chamber pressure pu for closing the second on-off valve 31 is set in advance.

In addition, in FIG. 3, curves ① to ② are expressed simply (average capacity is displayed) compared to curve ②, and the piston raising process is omitted from illustration. This is because it can be easily arrived at from curve ■.

Now, the die cushion capacity F is determined by the following formula.

F=PL ・AI −PI ・<Al−A2) Therefore, in the conventional structure shown in FIG. After Pa is established, the die cushion capacity reaches the lower limit LL, as shown by the dashed line in Fig. 3.
gradually increases to Fae at . buffer tank 6
Since the volume is 5 to 8 times larger, the wrinkle pressing force becomes 20 to 25% excessive at the lower limit LL where it is only possible to keep the required die cushion capacity Fa constant.

In the first embodiment, when the piston 2 is displaced downward from the first limit UL, the lower chamber pressure PL increases and the differential pressure with the upper chamber pressure Pl increases, so that the reference capacity F can be rapidly generated. I can do it. This rise becomes faster as the initial pressure in the lower chamber IL increases.

When the piston 2 continues to descend even after the reference capability F has been established, the control unit 50 forming the differential pressure value setting means uses the differential pressure determined based on the input from the pressure detector 12.33 and the capability signal. The pressure regulating valve 40 is controlled so that the differential pressure value corresponding to the capability signal outputted from the generating means 51 becomes equal. This defines the cracking pressure, and the first on-off valve 20 opens with this cracking pressure.

Then, the lower chamber IL and the upper chamber IU are communicated, the lower chamber pressure P[ falls, and the first on-off valve 20 closes again.

Therefore, the differential pressure changes while repeating minute fluctuations within the allowable range of the required wrinkle pressing force. Stroke STI
Until then, the reference capacity F can be held substantially constant.

Here, if the selection switching means 53 selects the curve ■ shown in FIG.
The curve (2) is successively extracted from the line sections stored in the capacity storage means 52 and output to the control unit 50. In this case, the first on-off valve 0 has a differential pressure setting means<40.50.
>, the capacity F is increased until the piston 2 reaches the lower limit L.
is controlled to keep it constant.

Now, for example, when the curve ■ is selected, the control unit 50 generates a curve based on the input from the capacity signal generating means 51, the input from the meat pressure detector 12.33, and the input from the angle detector 13. Control the pressure crab A regulating valve 40 so as to change the die cushion capacity according to the first
Controls the opening and closing of the on-off valve 2o. Die cushion ability is
The piston stroke during the press operation is lowered in stages after S'r'1, and thereafter is kept constant up to the lower limit LL.

In the case of curve ■, the change is gradually decreasing; in the case of curve ■, the change is gradual increasing; and in the case of curve ■, the change is gradually increasing.

On the other hand, the raising operation of the piston 2 from the lower limit LL is based on the differential pressure between the pressures pt and pu in both chambers, and initially matches the raising of the slide, and thereafter is performed smoothly under no load.

Since the lower chamber pressure PL is low and the upper chamber pressure Pu is high, the differential pressure rapidly decreases.

Then, when the upper chamber pressure Pu becomes equal to or higher than the set value set by the pressure setting device 56, the second on-off valve 31 is opened by a signal from the controller 55, and both chambers IU and IL are communicated with each other. Therefore, the pressures pt and pu in both chambers become equal, but the piston 2 is further raised by the push-up blade generated based on the effective area difference due to the presence or absence of the cross-sectional area A2 of the piston rod 3.

Although the upper limit ULt may be reached as is, in this embodiment, the second on-off valve 31 is closed again just before the upper limit UL surface. Therefore, the pressure Pu in the upper chamber increases slightly and rapidly lowers the pushing blade of the piston 2, so the upper limit U
It is possible to further enhance the damping effect at L.

It is also effective to open and close the blinking on-off valve 31 again when the piston 2 approaches the upper limit UL.

According to this embodiment, the upper chamber IU of the cylinder 1
first and second air passages 10 communicating with the lower chamber IL;
．． 30 is provided, and when the piston descends, the first air flow f￥8
10 (first on-off valve 20) to open and close the lower chamber pressure P.
The differential pressure between L and the upper chamber pressure Pu is controlled, and the second air flow path 30 (second on-off valve 31) is controlled to open and close at appropriate times during the rising process to prevent the upper chamber pressure PU from increasing. Therefore, there is no need to provide an excessively large buffer tank (6) in the conventional device, and it is very advantageous in terms of economy, installation space, and air consumption.

Further, the first air flow f#110 is formed to include a first on-off valve 20 having a check valve function, and the first on-off valve 20 has a check valve function.
The club king pressure is configured to be changed by the differential pressure 1i/f setting means (40, 50).Moreover, the differential pressure value setting means (40, 50) is set by the selection switching means 53.
．． Ability signal generation means 51 specified by ability storage means 52
Since the first on-off valve 20 is pressure differentially controlled based on the capacity signal output from the die cushion capacity, the die cushion capacity can be changed and adjusted according to a desired curve. Therefore, since the die cushion capacity can be changed during the press operation, it is possible to efficiently produce a variety of products with high quality, and at the same time, it is possible to reduce the cost of materials, without the inconvenience of limiting the form of the materials. 4. Quick start-up and fall adjustments can be achieved.

Further, the cylinder devices (1, 2) are of a closed type, and the die cushion capacity is configured to control the opening and closing of the first air flow path 10 and the second air flow path 30 to communicate and isolate the two chambers IUIL. Therefore, the conventional high-pressure, large-capacity compressor and rapid-acting large exhaust valve can be eliminated, making it compact and economical. In addition, the adjustment work of the die cushion capacity can be performed quickly and accurately because it is only necessary to change the setting of the crab king pressure of the first on-off valve 20, and the period of time required can be shortened and the press production efficiency can be increased. Furthermore, since the amount of air discharged for adjusting the die cushion capacity is, in principle, extremely small, the operating economy is also advantageous.

Furthermore, in the vicinity of the piston upper limit UL, the upper chamber pressure P
Since the differential pressure can be made small by keeping u, that is, by making the closing time of the second on-off valve 31 appropriate, it is possible to significantly reduce the impact force at the upper limit UL.

(Second example) This second embodiment is shown in FIG.

The second embodiment has a configuration that further simplifies the equipment compared to the first embodiment.

That is, the cylinder device (1, 2>, first on-off valve 20
, if the form and characteristics of the second on-off valve 31 are defined, the lower chamber pressure PL and the upper chamber pressure P during the upward and downward movements of the piston 2.
The relationship between u, the pressure PL in both chambers, the differential pressure between Pu1, the vertical movement of the slide, and the necessary wrinkle pressing force will become clear once the press mode and processed product are specified. Therefore, the first
This system controls the differential pressure of the on-off valve 20, but instead of directly detecting the pressure in both chambers or the differential pressure, these are replaced with the crankshaft angle.

Therefore, the pressure detector 12.33 in the first embodiment
is excluded.

Further, the reference capacity setting device 54 is not provided, and the die cushion capacity for the entire stroke of the piston 2 from the upper limit UL to the lower limit LL is stored in the capacity storage means 52. As a result, the control unit 50 controls the pressure regulating valve 40 while specifying the capability signal inputted from the capability signal generating means 51 using the crankshaft angle from the angle detector 13, and controls the cracking pressure of the first opening/closing valve 20. shall be set. In other words, while the first embodiment is a closed loop, the second embodiment forms an open loop 1 in which one curve read from the ability storage means 52 is used as a set value.

Further, the opening/closing control means for controlling the opening/closing of the second opening/closing valve 31 is formed only from a controller 55 which is a program sequencer. During the upward movement of the piston 2, the second on-off valve 31 is controlled to open and close in accordance with the crankshaft angle based on a predetermined procedure. However, in this embodiment, opening and closing control is performed at the same timing as in the first embodiment. Note that the opening/closing procedure and timing can be changed.

Therefore, in the case of the second embodiment, the crankshaft angle is used as an input, and it operates in the same manner as the first embodiment, and has the same effect as the first embodiment (conventional large buffer tank, high pressure large capacity compressor). , rapid cleaning of large exhaust valves, change and adjustment of die cushion capacity during press work, etc.).

Moreover, compared to the case of the first embodiment, the meat pressure detector (12,
33) and the simplification of the control unit 50, the structure can be further simplified and the cost can be reduced.

In addition, each operation is not defined as the differential pressure between the pressures pi and pu in both chambers, but is indirectly defined by the crankshaft angle, so if the performance diagram to be stored in the performance storage means 52 is clearly defined, The die cushion capacity during press work can be freely and easily automatically adjusted.

In each of the above embodiments, the control unit 50, the ability signal generation means 51, the ability storage means 52, the controller 55
．． 57 are formed separately, each of these means,
It may be formed integrally with a computer or the like including a CPU, RAM, ROM, etc.

[Effect of the invention 1] The present invention connects the upper and lower chambers of the cylinder through first and second air flow paths, and controls the differential pressure of the first on-off valve to adjust the die cushion capacity. Since the structure controls the opening and closing of the second on-off valve at the appropriate time during the piston rising process, it is compact and lightweight, has low operating costs, and is accurate and quick, eliminating the need for conventional large buffer tanks, high-pressure large-capacity compressors, rapid-acting large exhaust valves, etc. die cushion ability can be established.

Moreover, since the differential pressure control is performed based on the capacity diagram stored in the capacity storage means, the die cushion capacity during press operation can be changed and adjusted to the one appropriate for the product in question, so products of various shapes can be controlled. It has the excellent effect of being able to produce high quality and high efficiency.

[Brief explanation of the drawing]

FIG. 1 is an overall configuration diagram showing the first embodiment of the present invention, FIG. 2 is an overall configuration diagram without showing the second embodiment, and FIG. 3 is a comparison diagram of the operation of the conventional die cushion device. The diagram for explaining the operation and FIG. 4 are overall configuration diagrams of a conventional die cushion device. 1...Cylinder, IU...Upper chamber, Ishi...Lower chamber,
2... Piston, 10... First air flow path, 11... Piping, 20... First on-off valve, 21... Piping, 30... Second air flow path, 31... Second on-off valve, 40.50... Pressure regulating valve forming differential pressure value setting means, control unit, 51... Capacity signal generation means, 52... Capacity storage means, 53. ...Selection switching means. 54... Reference capacity setting device, 55.56... Controller forming opening/closing control means, pressure setting device, 57.58... Controller forming initial pressure setting means, pressure setting device. No.

Claims (1)

[Claims] (1) A lower chamber and an upper chamber sandwiching the piston of the cylinder are communicated with each other through a first air flow path having a first on-off valve and a second air flow path having a second on-off valve, and the first air flow path has a second on-off valve. The second on-off valve is formed to open when the pressure difference between the lower chamber pressure and the upper chamber pressure exceeds a set differential pressure value inputted from the differential pressure value setting means, and the second on-off valve is formed when the piston rises. Provided with opening/closing control means for controlling opening/closing at appropriate times during the process, ability storage means for storing a plurality of ability diagrams, and selection switching means for selecting one of the ability diagrams stored in the ability storage means, The press is characterized in that the die cushion capacity during press work can be changed and adjusted by changing the set differential pressure value output from the differential pressure value setting means based on the capacity diagram selected by the selection switching means. Pressure type die cushion device.