JP2000024723A - Pneumatic die cushion device for press machine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enable adjustment of the cushioning force of each cushion cylinder so that every die is provided with the optimum forming condition in the case plural works having a different shape are simultaneously formed with plural dies. SOLUTION: In a pneumatic die cushion device for presses in which at least one die 14 mounted on a bolster 13 is elastically supported with plural cushion pins 12, a pad 3 which is freely vertically movably provided in the bed 1 of this press is elastically supported with the cushion cylinders 4 consisting of an air cylinder and also air tanks and pressure regulating means for arbitrarily regulating the pressure in these air tanks are connected to each the cushion cylinder 4. By regulating the cushioning force of every cushion cylinder 4, the optimum forming condition of every die is set.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a pneumatic die cushion device for a press machine.

[0002]

2. Description of the Related Art Conventionally, when a relatively large panel or the like is formed by a press machine, a die cushion device is often used to prevent the panel from being wrinkled. In addition, die cushion devices for press machines include:
A pneumatic die cushion device in which a pad is elastically supported by a cushion cylinder composed of an air cylinder, a hydraulic die cushion device in which a pad is elastically supported by a hydraulic cylinder, and a die cushion device in which both air pressure and hydraulic pressure are used are known.

[0003] For example, Japanese Patent Publication No. 63-24770 proposes a die cushion device in which a pad is elastically supported by a cushion cylinder comprising one air cylinder.

In Japanese Utility Model Laid-Open No. 3-24397, 1
There has been proposed a die cushion device in which a pad is elastically supported by a cushion cylinder including a plurality of air cylinders and a plurality of hydraulic cylinders synchronized with each other.

Further, in Japanese Utility Model Laid-Open Publication No. 6-66822,
A die cushion device has been proposed in which a plurality of hydraulic cylinders are provided on a pad, and these hydraulic cylinders absorb a deviation in the length of a die cushion pin.

[0006]

Of the above publications, Japanese Patent Publication No. Sho 63-24770 discloses a pad in which a pad is elastically supported by one cushion cylinder.
When simultaneously molding a plurality of workpieces having different shapes using a plurality of molds, it is not possible to control such as setting the optimal molding conditions for each mold, so that wrinkles are formed on only one of the molded workpieces, for example. There are problems such as occurrence.

A die cushion device in which a pad a is elastically supported by a cushion cylinder b composed of a plurality of air cylinders as shown in FIG. 1 is also employed in a conventional relatively large press machine. In this case, since the cushion cylinders b are simultaneously controlled by the common pressure reducing valve c, the cushion cylinders b have the same cushioning force and cannot be individually adjusted.

On the other hand, as disclosed in Japanese Utility Model Laid-Open No. 3-24397, a pad is supported by a plurality of hydraulic cylinders. However, since the hydraulic cylinders are synchronized with each other, a plurality of molds are used. When molding a plurality of workpieces having different shapes at the same time, wrinkles occur on one of the molded workpieces, for example, because control such as setting the optimal molding conditions for each mold cannot be performed as in the above publication. Problems such as doing so cannot be eliminated.

Further, in the die cushion device using the hydraulic pressure, the surroundings are soiled by oil leakage or the oil needs to be periodically replaced. There are also problems such as the need for valves and the like, which makes the apparatus complicated and expensive.

SUMMARY OF THE INVENTION The present invention has been made to solve such a conventional problem, and provides a pneumatic die cushion device of a press machine capable of individually controlling a plurality of cushion cylinders for supporting pads. It is possible to simultaneously mold a plurality of workpieces having different shapes with high precision.

[0011]

In order to achieve the above object, according to the first aspect of the present invention, at least one mold installed on a bolster is elastically supported via a plurality of cushion pins. In a pneumatic die cushion device of a press machine, a pad provided movably up and down in a bed of the press machine is elastically supported by a plurality of cushion cylinders composed of air cylinders. And pressure adjusting means for arbitrarily adjusting the pressure in the air tank.

With the above configuration, when a plurality of workpieces having different shapes are simultaneously formed by a plurality of dies installed on the bolster, or when an asymmetrical workpiece is formed, the optimum molding conditions are set for each of the dies. In addition, since the cushion force of each cushion cylinder can be adjusted, highly accurate molding can be performed, and problems such as generation of wrinkles on a part of a plurality of molded workpieces can be solved.

Further, since the air cylinder is used for the cushion cylinder, the surroundings are not contaminated by oil leakage, and there is no need to periodically change the oil. Since the pressure adjusting means can be configured with a small number of components, the number of components can be reduced as compared with the hydraulic die cushion device, and the configuration is simplified, so that the device can be provided at low cost.

[0014]

Embodiments of the present invention will be described in detail with reference to the drawings shown in FIG. 2 is a sectional view of a pneumatic die cushion device provided in a press machine, FIG. 3 is a plan view showing pads of the device, and FIG. 4 is a circuit diagram of the device.

In FIG. 2, 1 is a bed of a press machine,
The main body 2 of the die cushion device is installed in the bed 1. The main body 2 includes a board-shaped pad 3 provided in the bed 1 so as to be movable up and down, and a plurality of, for example, two cushion cylinders 4 elastically supporting the pad 3 from below. The cushion cylinder 4 be constituted by an air cylinder, with are installed apart in the lateral direction as shown in FIG. 3, each cushioning cylinder 4 in the upper chamber 4 ₁ and the lower chamber 4 ₂ by the piston 4a The distal ends of the piston rods 4b projecting upward from the pistons 4a are attached to the lower surface of the pad 3.

The lower chamber 4 of each cushion cylinder 4
_As shown in FIG. 4, a check valve 2 is provided on the air line 7 provided for each cushion cylinder 4 and a pressure control means 8 downstream of a pressure reducing valve by a conduit 6 provided with a solenoid valve 5 on the way. The upstream side of each pressure adjusting means 8 is connected to a common air source 10.

On the other hand, a large number of pin holes 1a are formed in the bed 1 at intervals in the vertical and horizontal directions.
The cushion pin 12 is selectively inserted into the rim. The lower ends of the cushion pins 12 are in contact with the upper surface of the pad 3, and the upper ends reach the upper surface of the bolster 13 a through pin holes 13 a in the bolster 13 installed on the bed 1. Is in contact with the lower surfaces of the plurality of dies 14 installed in the dies.

A total of two dies 14 are provided, for example, one above each cushion cylinder 4, and have different shapes as shown in FIG. 5A, such as front and rear doors of an automobile. 15 can be simultaneously formed with a mold (both not shown) attached to a slide of a press machine.

Next, the operation of the pneumatic die cushion device constructed as described above will be described. A plurality of workpieces 15 having different shapes are simultaneously formed using a plurality of dies 14 installed on the bolster 13. Then, in order to obtain optimum forming conditions according to the work 15 to be formed, the cushion forces F ₁ and F ₂ of each cushion cylinder 4 are adjusted. In adjusting the cushion forces F ₁ and F ₂ , the pressure adjustment means 8 provided for each cushion cylinder 4 is adjusted to set the pressures P ₁ and P ₂ in the air tank 7 to predetermined values.

Incidentally, the pressures P ₁ and P ₂ correspond to the work 15
The accumulated data is used with empirical numerical values for obtaining optimum molding conditions different from one another.

As described above, each cushion cylinder 4
After the optimum molding conditions are set for each, the operation of the press machine is started to perform the press molding, and the optimal molding conditions are obtained for each of the dies 14 elastically supported on the pads 3 via the cushion pins 12. Since the cushioning forces F ₁ and F ₂ are set so as to be able to be formed, even when a plurality of works 15 are formed at the same time, wrinkles do not occur on only one of the works 15 and high-precision forming is possible. .

In the above-described embodiment, the case where two dies 14 are installed on the bolster 13 and a plurality of works 15 having different shapes are simultaneously formed by the dies 14 has been described. As shown in (b), even when a left-right asymmetrical work 15 is formed by a single mold 14, by adjusting the cushion forces F ₁ and F ₂ of the cushion cylinders 4 respectively, wrinkle-free precision can be obtained. A high work 15 can be formed.

Further, in the above-described embodiment, an example in which two cushion cylinders 4 are arranged on the left and right has been described. However, three cushion cylinders 4 are arranged on the left and right and the center as shown in FIG. May be arranged at the corners of, or may be five or more. In any case, it is needless to say that the air tank 7 and the pressure adjusting means 8 are provided for each of the cushion cylinders 4 so that the optimum molding conditions can be set for each of the cushion cylinders 4. When more than one cushion cylinders 4 are arranged, the dies 14 may be installed above each cushion cylinder 4 by the number of cushion cylinders 4 or more.

[Brief description of the drawings]

FIG. 1 is a circuit diagram showing a pneumatic die cushion device of a conventional press machine.

FIG. 2 is a sectional view showing a pneumatic die cushion device of the press machine according to the embodiment of the present invention.

FIG. 3 is a view from arrow A in FIG. 2;

FIG. 4 is a circuit diagram showing a pneumatic die cushion device of a press machine according to an embodiment of the present invention.

FIGS. 5A and 5B are explanatory views showing a work formed by a press machine.

FIG. 6 is an explanatory diagram showing another arrangement example of the cushion cylinder.

FIG. 7 is an explanatory diagram showing another arrangement example of the cushion cylinder.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Bed 3 ... Pad 4 ... Cushion cylinder 7 ... Air tank 8 ... Pressure adjusting means

Claims (1)

[Claims] At least one mold (14) installed on a bolster (13) is provided with a plurality of cushion pins (1).
In a pneumatic die cushion device of a press machine which is elastically supported via 2), a pad (3) provided vertically movable in a bed (1) of the press machine is provided with:
Multiple cushion cylinders composed of air cylinders (4)
With elastic support and cushion cylinders (4)
An air tank (7) and a pressure adjusting means (8) for arbitrarily adjusting the pressure in the air tank (7).