JPH0428720Y2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention relates to a device for automatically setting a press load in a press machine, particularly a mechanical double-acting press machine equipped with a hydraulic system including a hydro blank holder.

(Prior Art) Mechanical double-acting presses are usually equipped with a hydraulic system for detecting overload. As shown in FIG. 2, this hydraulic blank holder 4 has an oil chamber 2 and an air chamber 3 defined by a piston 1, and the oil chamber 2 is connected to a connection screw 5 on the machine side. It is connected to an oil chamber 7 at the connection part with the slide 6, and a predetermined hydraulic pressure is supplied to this from a hydraulic system 10 including an oil tank 8, a pump/motor unit 9, etc., while an air source 11 and a regulator are connected to the air chamber 3. 12, air tank 1
A predetermined air pressure is supplied from a pneumatic device 14 including 3 and the like. With such a configuration, if an overload occurs during press forming, the oil pressure in the oil chamber 7 below the connection screw 5 increases,
The oil pressure is transmitted to the oil chamber 3 in the hydro blank holder 4, causing the piston 1 to move upward, and as a result, the rod 1a extending from the piston 1 engages with a limit switch (not shown) to stop the press machine. Become.

By the way, in the case of a press machine equipped with the above-mentioned hydraulic pressure system, by appropriately balancing the hydraulic pressure and air pressure in the hydro blank holder 4, the load increase of the press machine can be controlled via the hydraulic pressure under the connection screw 5. It is now transmitted to the press mold,
In this case, the press load is determined not only by the push-in amount (die height) of the slide 6 but also by the air pressure supplied to the hydro blank holder 4, that is, the set pressure of the regulator 12.

(Problems to be Solved by the Invention) However, conventionally, adjusting the set pressure of the regulator 12 has been done manually by a person while looking at a meter, and therefore it takes much time to adjust. Another problem was that fine adjustment was difficult and reproducibility was poor. In addition, such a problem becomes a major obstacle in resolving the mechanical differences between the press machines used in the mold manufacturing stage and the press machines used on the production line, and as a result, adjustment of the press molds becomes unavoidable. The current situation was such that mold production costs had to increase significantly.

(Means for Solving the Problems) The present invention was made to solve the above problems, and in a press machine equipped with a hydraulic system including a hydro blank holder, the air chamber of the hydro blank holder and A pressure control valve and a pressure reducing valve device for reducing the air pressure in the air chamber are interposed in a main pipe line connecting the air source, and a pilot pressure is applied to the pressure control valve and the pressure reducing valve device provided in parallel with the main pipe line. An electro-pneumatic proportional valve for controlling the pressure control valve and the pressure reducing valve device is interposed in the pilot pipe for supplying the air, and a detection unit for detecting the air pressure in the air chamber and a control signal corresponding to the set air pressure are output. A pressure control device that controls the electro-pneumatic proportional valve and also includes a control section that performs feedback control of the electro-pneumatic proportional valve so that a set air pressure is obtained based on the signal from the detection section. This is the summary.

(Function) In the press load setting device configured as described above, when a set air pressure is input to the control section, a control signal corresponding to the set air pressure is sent from the control section to the electro-pneumatic proportional valve, which is followed by an electro-pneumatic proportional valve. An air signal corresponding to the control signal is sent from the valve to the pressure control valve;
As a result, the pressure control valve is activated and the set air pressure is supplied to the air chamber of the hydro blank holder. However, when the detection unit detects that the air chamber has not reached the set air pressure, the control unit again sends a control signal to the electropneumatic proportional valve, thereby causing the air chamber to have the desired air pressure. will be set. On the other hand, when the set air pressure is to be changed to a lower value side, the pressure reducing valve device is actuated in advance by the air signal from the electropneumatic proportional valve to reduce the pressure in the air chamber, and then the above setting operation is performed and the pressure in the air chamber is reduced. The desired air pressure is set in the same manner as above.

That is, it becomes possible to automatically supply the set air pressure to the air chamber of the hydro blank holder and to manage this with high precision.

(Example) Hereinafter, an example of the present invention will be described based on the accompanying drawings.

FIG. 1 shows a press load setting device according to the present invention. In this figure, the same parts as those shown in the above-mentioned FIG. 2 are given the same reference numerals, and the explanation thereof will be omitted. In Figure 1, 15
is a main pipe connecting the air source 11 and the air tank 13; a pressure control valve 16 is interposed in the main pipe 15; A check valve 17, a switching valve 18, and a relief valve 19 are interposed, which constitute a pressure reducing valve device for reducing the pressure. Further, a pilot pipe 20 is arranged in parallel with the main pipe 15, and an electropneumatic proportional valve 21 is interposed therein.
The pilot pipe line 20 branches off the outlet side end of the electro-pneumatic proportional valve 21 and connects to the pressure control valve 16 and the relief valve 19, respectively.
The air signal from 1 is sent to the pressure control valve 15 and the relief valve 19 at the same time.

A control section 24 in a pressure control device 23 is connected to the electropneumatic proportional valve 21 via a wiring 22. The control unit 24 has a function of sending out a control signal corresponding to a desired set air pressure, and therefore the electropneumatic proportional valve 21 communicates with the pressure control valve 16 with an air signal corresponding to the control signal. It controls the relief valve 19. The pressure control device 23 is also provided with a detection section 25 that detects the air pressure within the air tank 13, and a pressure signal is sent from the detection section 25 to the control section 24. In addition to the function of sending out a control signal corresponding to the set air pressure, the control unit 24 compares the actual air pressure in the air tank 13 with the set air pressure based on the signal from the detection unit 24, and sends out a correction signal. This function allows so-called feedback control to be executed. The pressure control device 23 is provided with an input board for inputting the set air pressure, a CRT for displaying the set air pressure, and the like.

Here, a press machine is normally provided with four connection screws 5 (FIG. 2), and in this embodiment, the air source 11 is shared and the pressure control device 23 described above is included. Air pressure control circuit 2
6, Air tank 13, Hydro blank holder 4
Four pneumatic systems are provided corresponding to each connection screw. In FIG. 1, numerals 26b, 26c, and 26d indicate pneumatic control circuits corresponding to the pneumatic pressure control circuit 26,
Reference numerals 13b, 13c, and 13d represent air tanks corresponding to the air tank 13, respectively.

With this configuration, when a predetermined air pressure is to be set in the air tank 13, the set air pressure is input to the control unit 24 using an input board (not shown). Then, a control signal corresponding to the set air pressure is sent from the control section 24 to the electropneumatic proportional valve 21,
Following this, an air signal corresponding to the control signal is sent from the electropneumatic proportional valve 21 to the pressure control valve 16. The pressure control valve 16 then reduces the high pressure air supplied from the air source 11 to the set air pressure, thereby supplying the air tank 13 with the set air pressure. Thus, the air pressure within the air tank 13 is detected by the detection section 25, and a signal thereof is sent to the control section 24. The control unit 24 receives the pressure signal and compares it with the set air pressure, and when the difference is greater than a predetermined value, it outputs a control signal to the electropneumatic proportional valve 21 again, and the same setting work as above is performed. A desired air pressure is set in the air tank 13. Here, when the set air pressure is changed to a lower value side, the relief valve 19 is opened by the air signal sent out in advance from the electropneumatic proportional valve 21, and at the same time the switching valve 18 is switched to reduce the pressure inside the air tank 13. After that, after waiting for the relief valve 19 and the switching valve 18 to return, the above setting work is performed, and the air tank 1
3 is set to a desired air pressure.

That is, not only is it possible to automatically set the air pressure for the hydro blank holder 4, but also to manage it with high precision, and as a result, it is possible to automatically set the press load and manage it with high precision. In addition, since the press load can be set independently for each connection screw 5, it is possible to manage press formability for each part, and more stable improvements in formability can be achieved. It becomes like this.

In the above embodiment, an independent pneumatic system including the pneumatic control circuit 26 and the like is provided for each connection screw, but it goes without saying that a common pneumatic system may be provided instead.

(Effects of the invention) As explained above in detail, the present invention provides a pressure control valve and a pressure reducing valve device in the main pipe connecting the air chamber of the hydro blank holder and the air source, and also provides a pressure control valve and a pressure reducing valve device in the pilot pipe. An electro-pneumatic proportional valve that controls the pressure control valve and the pressure reducing valve device is installed, and a pressure control device that can send a control signal corresponding to the set air pressure to the electro-pneumatic proportional valve is installed, so that the pressure control device can be set. By simply inputting the air pressure, the air pressure can be automatically set, which has the effect of speeding up press load setting.

In addition, the pressure control device has a function that detects the air pressure inside the hydro blank holder and provides feedback control of the electro-pneumatic proportional valve, which improves the accuracy of setting the air pressure and therefore the press load. This has the effect of reducing mold modification man-hours and significantly reducing mold manufacturing costs.

[Brief explanation of the drawing]

FIG. 1 is a hydraulic pressure circuit diagram of a press load setting device according to the present invention, and FIG. 2 is a hydraulic pressure circuit diagram of a conventional press load setting device. 2...Oil chamber, 3...Air chamber, 4...Hydro blank holder, 11...Air source, 13...Air tank, 15...Main pipe, 16...Pressure control valve, 1
7...Check valve, 18...Switching valve, 19...Relief valve, 20...Pilot pipe line, 21...Electro-pneumatic proportional valve, 23...Pressure control device, 24...Control unit,
25...detection section.

Claims (1)

[Scope of utility model registration request] In a press machine equipped with a hydraulic system including a hydro blank holder, a pressure control valve and a pressure reducing valve device for reducing the air pressure in the air chamber are interposed in the main pipe connecting the air chamber of the hydro blank holder and the air source. and an electropneumatic proportional valve for controlling the pressure control valve and the pressure reducing valve device is interposed in a pilot line that is provided in parallel with the main pipe and supplies pilot pressure to the pressure control valve and the pressure reducing valve device, Furthermore, the electro-pneumatic proportional valve is controlled by a detection section that detects the air pressure in the air chamber and a control signal corresponding to the set air pressure is output, and the electro-pneumatic proportional valve is controlled so that the set air pressure is obtained based on the signal from the detection section. 1. A press load setting device comprising a pressure control device including a control section that performs feedback control of a proportional valve.