JPH02192829A - Die spring system - Google Patents

Abstract

PURPOSE:To give uniform surface pressure to a pressure pad by providing a gas passage to communicate each gas chamber of plural cylinders to each other. CONSTITUTION:The gas chamber 80 is provided on the side enclosed by the outside of a bellows 45 of the corresponding cylinder 21 and the inside wall of the cylinder 21 to seal inert gas. The gas pressure acts in such a direction that the bellows is closed, that is, a rod 22 is pushed out of the cylinder 21. The gas chambers 80, 80 of plural die springs 20, 20 are communicated to each other by the gas passage 95. Consequently, though oil leaks from one of the die springs 20 or the amounts of leaked oil in each spring 20, 20 scatter, pressure is equal between the gas chambers. As a result, the pressure pad can be always pressurized by uniform pressure.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a die spring system equipped with a plurality of gas-filled die rings used in press working machines and the like.

[Prior Art] There are various types of press working, and for example, taking the well-known deep drawing as an example, pressing is performed through steps a to e as shown in FIG. That is, in step a, the blank 1 is placed on the die 2, and the die 2 is placed on the die 2.
A pressure pad 3 and a punch 4 for suppressing wrinkles are arranged on the upper surface side in the figure. In the step, the pressure pad 3 is lowered to press the peripheral edge of the blank 1. By lowering the punch 4 in step C, a product 1' squeezed to a desired depth is obtained. After that, in step d, pad 3 and punch 4
is raised and the product 1' is taken out from the die 2 by the knockout member 5 in step e.

If the load applied to the pad 3 is too weak, wrinkles will occur in the processed product 1'. On the other hand, if the load is too strong, defects such as breakage of the blank 1 will occur during processing, so it is necessary to apply an appropriate wrinkle pressing force to obtain a perfect product 1'.

As a mechanism for generating this wrinkle pressing force, a die ring is used in normal press working. A coil spring is generally used as a die ring, but an elastic block made of hard urethane or the like may be used when a particularly heavy load is required. However, it is practically impossible to use hard urethane with a small deflection stroke, especially in a press machine with a large processing stroke such as deep drawing. Furthermore, when a coiled spring is used, there are drawbacks such as increased dimensions. Further, both the coiled spring and the hard urethane have a large spring constant, which inevitably causes a large change in the wrinkle pressing force during press working, which tends to cause the blank 1 to break.

Therefore, there is a tendency for gas spring type die rings to be used in place of conventional coil springs and hard urethane. For example, the die ring 6 illustrated in FIG.
High-pressure gas is sealed inside the cylinder 7, and a rod 8 is movably inserted into the cylinder 7, and the pressure of the gas inside the cylinder 7 acts in a direction to push the rod 8 out. Alternatively, as shown in FIG. 8, a die ring has been proposed in which a free piston 10 is provided inside the cylinder 7 to partition the inside of the cylinder 7 into an air chamber 11 and a liquid chamber 12.

[Problem to be solved by the invention] In the above-mentioned pressing process (see Fig. 6), the product 1'
In some cases, it is required to keep the surface pressure of the pressure pad 3 uniform. However, if the structure of the conventional gas spring type die ring is such that gas leaks easily, when one pad 3 is pressed by multiple die rings, the degree of gas leakage or oil leakage in each die ring may vary. Due to this variation, it is not possible to apply a uniform surface pressure to the pressure pad 3.

Therefore, it is an object of the present invention to provide a die spring in which a plurality of gas spring type die springs are used, and which can apply uniform surface pressure to the pressure pad even if any die spring leaks. Our goal is to provide a spring system.

[Means for Solving the Problems] The die spring system of the present invention developed to achieve the above object includes a plurality of hollow cylinders, a rod inserted into each cylinder so as to be movable in the axial direction,
A bellows is housed inside each of the cylinders and has a metal bellows body that is expandable and retractable in the axial direction of the cylinder. and an air chamber located on the other side of the space inside the cylinder partitioned by the bellows, which is filled with gas at a pressure higher than atmospheric pressure, and in which the pressure of the gas acts in a direction to push the rod out of the cylinder. and a gas passage that allows the air chambers of the plurality of cylinders to communicate with each other.

[Operation] The pressure of the gas sealed in the air chamber in the cylinder acts on the liquid chamber through the metal bellows, and the rod receives a load in the direction of being pushed out of the cylinder. This load is used as a force to press the blank during press working. When the rod moves in the direction of being pushed into the cylinder (shrinking side) as the die descends during press working, the air chamber is further compressed as the rod is pushed into the cylinder, causing the bellows to close. is deflected in the axial direction. During the mold oven, when the rod moves in the direction of protruding from the cylinder (extension side), the volume of the air chamber expands as the rod moves.

The air chambers of each cylinder communicate with each other via gas passages, so even if liquid leaks from the liquid chamber of one of the cylinders for some reason and causes an imbalance in liquid volume, the air chambers of each cylinder communicate with each other via the gas passages. Since the pressure in each cylinder is kept the same, uniform surface pressure can be applied to the pressure pads and the like.

[Example] The first example of the present invention will be described below with reference to Figures 1 to 4.
This will be explained with reference to the figures.

The die spring system 19 shown in FIG. 1 includes a plurality of die springs 20.degree. 20 (two in the illustrated example). As illustrated in FIG. 3, the die bring 20.
20 is provided in the holder on the punch 4 side, and the punch 4
When it descends, it presses a pressure pad 3 for wrinkle straightening toward the blank 1 on the die 2. Since each die ring 20.2'0 has the same configuration,
One die ring 20 will be explained below as a representative.

As shown enlarged in FIG. 2, the die ring 20 is
It includes a hollow cylinder 21 and a rod 22. Inside the cylinder 21, an inner cylindrical portion 23 is provided concentrically with the cylinder 21.
is provided. A communication port 25 is opened in an end member 24 located at the lower end of the inner cylinder portion 23 in the drawing.

The rod 22 is inserted into the cylinder 21 so as to be movable in its axial direction, and a piston-shaped portion 30 is provided at the inner end of the rod 22 .

This piston portion 30 comes into sliding contact with the inner circumferential surface of the inner cylinder portion 23 via a sliding bearing 31 .

At the illustrated upper end of the cylinder 21, a sliding bearing 34 and a sealing means 35 for sealing the sliding portion with respect to the rod 22 are provided on the inner circumference of the portion through which the rod 22 passes. This sealing means 35 includes a high-pressure seal member 36, a low-pressure seal member 37 provided on the lower pressure side, that is, the atmosphere side, than this seal member 36, and a dust seal 38.
Consists of etc. The rebound stopper 39 is made of an elastic material such as urethane elastomer. This stopper 39
defines the end of the stroke in this direction when the rod 22 moves to the extension side.

A metal bellows 45 is housed inside the cylinder 21 . The bellows 45 includes a bellows body 46 that is expandable and retractable in the axial direction of the cylinder 21, and a bellows cap 47 that closes one end of the bellows body 46. The bellows body 46 has a thickness of 0.1 to 0.3.
It consists of stainless steel plates at the front and back of the fin. However, metals other than stainless steel may be used, and plate thicknesses other than those mentioned above may be used. The other end 48 of the bellows body 46 is fixed to an end wall 49 of the cylinder 21.

A valve body 50 is provided on the inner surface of the bellows cap 47. The valve body 50 is made of a rubber-like elastic material such as urethane elastomer or silicone resin, and faces the annular valve seat 51 formed around the above-mentioned flow port 25. These valve body 50 and valve seat 51 are connected to the inner cylindrical portion 23 when the bellows 45 is contracted by a predetermined amount or more, as will be described later.
A self-sealing means 52 for trapping oil between the bellows body 46 and the bellows body 46 is provided.

A bellows guide member 5 is attached to the outer periphery of the bellows body 46.
5.56 is provided. These guide members 55.
56 is for securing a predetermined clearance between the bellows body 46 and the cylinder 21, and for ensuring a predetermined clearance between the bellows body 46 and the cylinder 21.
This is used to reduce the sliding resistance between the cylinder 21 and the cylinder 21.

Of the internal space of the cylinder 21 partitioned by the bellows 45, the side where the sealing means 35 is provided;
That is, a liquid chamber 60 is defined on the inner surface side of the bellows 45. This liquid chamber 60 is filled with oil as an example of liquid. A hole 63 that can be closed by a ball 61 and a screw 6da is provided in the upper part of the liquid chamber 60.

The liquid chamber 60 is formed by the piston portion 30 described above.
The first liquid chamber 60a on the upper side in the figure and the second liquid chamber 60b on the lower side in the figure
It is divided into two parts.

The piston portion 30 is provided with a first orifice 71, a second orifice 72, and a third orifice 73 as damping force generating means 70. 1st orifice 7
1 passes through the piston portion 30 in the axial direction, and the first
It communicates with the liquid chamber 60a and the second liquid chamber 60b. The second orifice 72 penetrates the rod 22 in the radial direction,
It communicates with the first liquid chamber 60a.

The third orifice 73 is a poppet valve type one-way valve 7.
5, it can be opened and closed. That is, this one-way valve 75 is housed on the second orifice 72 side, that is, on the side that communicates with the first liquid chamber 60a, and is biased by a compression spring 76 in a direction to close the third orifice 73. This one-way valve 75 is connected to the second liquid chamber 60b.
When the pressure in the first liquid chamber 60a becomes greater than a certain value, the valve opens against the reaction force of the spring 76.

Note that the damping force generating means 70 may be provided, for example, at the communication port 25 of the end member 24 instead of being provided at the piston portion 30 as in the above embodiment. It is sufficient if it is provided at a location where the liquid flows. Further, the damping force generating means 70 may be configured to be able to adjust the damping force on the extension side of the rod 22 in two or more stages, or may be configured to be able to continuously adjust the damping force on the extension side in a stepless manner. Further, the damping force generating means 70 is not limited to the poppet valve type as in this embodiment, but may be configured to make the damping force on the extension side of the rod 22 larger than on the contraction side, for example, by combining a plurality of plate valves. may have been done.

An air chamber 80 is provided in the internal space of the cylinder 21 on the side where the sealing means 35 is not provided, that is, on the side surrounded by the outer surface of the bellows 45 and the inner wall of the cylinder 21. This air chamber 80 is filled with an inert gas such as nitrogen. The pressure at which the gas is sealed is determined depending on the wrinkle-removal force required for the die ring 20, and the gas is sealed at a high pressure of, for example, several tens of kg/cm or more. The pressure of this gas acts in the direction of contracting the bellows 45, that is, in the direction of pushing the rod 22 out of the cylinder 21. A gas supply port 82 provided in an end wall 81 of the cylinder 21 can be closed with a plug 83 . Note that an air chamber 80 is provided at an appropriate position in the die ring 20 of this embodiment.
A safety valve is provided that opens when the pressure rises above a predetermined value.

A plurality of die rings 2'0.
The twenty air chambers 80, 80 are communicated with each other by a gas passage 95. The end 95a side of the gas passage 95 is closed. However, if necessary, another cylinder, an accumulator, or another gas supply port may be connected to the gas passage 95.

The process of supplying gas to the air chamber 80 is as follows.

When supplying gas, the liquid chamber 60 is filled with oil in advance. The hole 63 is left open. A pressurized gas supply source is connected through the gas supply port 82 to supply gas into the air chamber 80 .

As the amount of gas in the air chamber 80 increases, the bellows body 46 contracts in the axial direction. Therefore, part of the oil in the liquid chamber 60 is discharged to the outside through the hole 63. When the bellows 45 is bent to a predetermined stroke, the self-sealing means 5
Since the valve body 50 of No. 2 comes into close contact with the valve seat 51, the flow port 2
5 is occluded. Therefore, the bellows body 46 no longer bends in the axial direction, and oil is trapped in the gap 92 between the outer peripheral surface of the inner cylinder portion 23 and the inner surface of the bellows body 46.

Since gas continues to be supplied to the air chamber 80 even after the valve body 50 comes into close contact with the valve seat 51, the pressure in the air chamber 80 gradually increases. Oil is substantially incompressible. Therefore, the entire inner surface of the bellows body 46 is evenly supported by the oil trapped in the gap 92. Therefore, even if gas is continuously supplied at high pressure, there is no risk that the bellows 45 will bend excessively. When the pressure in the air chamber 80 reaches a predetermined value, the gas supply is stopped and the supply port 82 is closed to the plug 83.
blocked by. Further, the hole 63 is closed by the screw 62.

The die ring 20, 20 whose air chamber 80 is filled with gas at a predetermined pressure as described above is assembled at a position where it can press the pressure pad 3 of the press machine. During press working, as the punch 4 descends, the rod 22 moves in the direction of being pushed into the cylinder 21. At this time, the amount of insertion of the rod 22 into the cylinder 21 increases. Therefore, the air chamber 80 is compressed by the amount that the rod 22 has moved, the bellows 45 is expanded, and the pressure in the air chamber 80 is increased.

In this way, when the rod 22 moves to the contraction side, the second
Since the pressure in the liquid chamber 60b becomes higher than the pressure in the first liquid chamber 60a, a part of the oil in the second liquid chamber 60b is released by opening the one-way valve 75 as shown in FIG. The first liquid chamber 60 passes through the second orifice 72 and the third orifice 73.
Flows to the a side.

At the same time, part of the oil in the second liquid chamber 60b flows into the first liquid chamber 60a through the first orifice 71. In this way, since the number of channels increases on the contracting side of the rod 22, a relatively small damping force is generated. Therefore, appropriate wrinkle smoothing power is exhibited.

When the die is driven toward the oven after pressing, the rod 22 moves toward the extension side relative to the cylinder 21. At this time, the pressure in the first liquid chamber 60a becomes higher than that in the second liquid chamber 60b, so the one-way valve 75 is closed. Therefore, the water flows only through the first orifice 71, and a large damping force is generated. Since the speed of the extension side of the rod 22 is kept low in this way, the pressure pad 3 is prevented from rising rapidly, and the pressed product can be held down for a certain period of time. When the rod 22 moves to the extension side, the volume of the air chamber 80 increases by the amount that the rod 22 moves, so the bellows 45 returns to its original deflection.

The gas in the air chamber 80 is transferred to the liquid chamber 6 by the metal bellows 45.
It is completely separated from the oil inside. Even if the metal bellows 45 is thin, it exhibits extremely good gas barrier properties. Therefore, the gas in the air chamber 80 does not dissolve into the oil in the liquid chamber 60.

Since there is no sliding part in the air chamber 80 that communicates with the atmosphere, even if the rod 22 is repeatedly moved back and forth at high speed,
It is inevitable that the gas in the air chamber 80 will escape directly to the atmosphere through the sliding portion of the rod 22. Since the sealing means 35 for sealing the sliding portion of the rod 22 is provided on the liquid chamber 60 side, it is sufficient that the sealing means 35 can seal oil. It is relatively easy to seal oil, which has a high viscosity compared to gas.

If oil leaks from the sealing means 35 for some reason, the volume of the air chamber 80 will increase relatively as the amount of liquid in the liquid chamber 60 decreases. Dice bring 2 of this example
Since the air chambers 80 and 80 of 0.20 mm are in communication with each other through the gas passage 95, one die ring 20
Even if oil leaks from the air chambers 20, 20 or there are variations in the amount of oil leaking from each spring 20, 20, the pressure between the air chambers 80, 80 becomes equal. Therefore, the pressure pad 3 can be suppressed with constant blood pressure.

In addition, the die ring 20 of this embodiment has the bellows body 4 when the deflection of the bellows 45 exceeds a predetermined stroke.
6 is provided with a self-sealing means 52 for trapping oil on the inner surface side. Therefore, even if the oil in the liquid chamber 60 escapes for some reason and the pressure of high-pressure gas acts in a direction that bends the bellows 45, the bellows will close until the valve body 50 is in close contact with the valve seat 51. 45 is bent, oil is trapped in the gap 92. This oil enables the bellows body 46 to be evenly supported from the inner surface side. Therefore, excessive bending of the bellows body 46 can be prevented, which is effective in protecting the bellows 45.

FIG. 5 shows a second embodiment of the present invention. In this embodiment, a hydraulic circuit 1 as an example of a liquid feeding means is connected to the liquid chamber 60.60 of each spring 20.20 via a liquid passage 100.
01 is connected. This hydraulic circuit 101 includes a first pressure regulating valve 102, a second pressure regulating valve 103, an accumulator 104, a check valve 105, and an oil pump 10.
6, an oil tank 107, etc. The oil pressure in the pipeline from the pump 10B to the first pressure regulating valve 102 is kept constant by the action of the second pressure regulating valve 103. Also,
A valve 108 and a pressure gauge 109 are provided in the gas passage 95.

The gas passage 95 may be connected to another cylinder, an accumulator, a gas common supply source, or the like.

In the second embodiment described above, when the oil in the liquid chamber 60 leaks at the sealing means 35 and the pressure in the cylinder 21 decreases, the pressure regulating valve 102 is operated and the oil is kept in the liquid chamber 60 until a constant pressure is reached. sent to. When the pressure inside the cylinder 21 reaches the set value, the pressure regulating valve 102
closes. This prevents a decrease in the spring constant and set load (wrinkle straightening force) due to oil leakage, and ensures a constant spring constant at all times. The pump 106 may be driven by an electric motor, but since oil leakage from the sealing means 35 is extremely small, a small-capacity manual pump will suffice.

[Effects of the Invention] According to the present invention, when a plurality of gas spring type die rings are used, even if one of the springs leaks or there is variation in the leakage amount for each spring, , it is possible to always generate even surface pressure.

[Brief explanation of the drawing]

FIG. 1 is a longitudinal cross-sectional view of a die spring system showing a first embodiment of the present invention, FIG. 2 is a cross-sectional view of one spring in the die spring system shown in FIG. 1, and FIG.
The figure is a side view of a press machine showing an example of how the die ring is used, FIG. 4 is an enlarged view showing the one-way valve in FIG. 1 in an open state, and FIG. 5 is a second embodiment of the present invention. FIG. 6 is a sectional view of a die spring system showing an example, FIG. 6 is an explanatory diagram of a deep drawing process, and FIGS. 7 and 8 are longitudinal sectional views showing conventional die springs, respectively. 20... Dice ring, 21... Cylinder, 22
... Rod, 35 ... Sealing means, 45 ... Metal bellows, 46 ... Bellows body, 60 ... Liquid chamber,
70... Damping force generating means, 80... Air chamber, 95...
- Gas passage, 100...liquid passage, toi...liquid feeding means. Applicant's agent Patent attorney Takehiko Suzue 1 Figure Figure Figure Figure Figure Procedure Kozue J Official Director General of the Patent Office Yoshi 1) Tsuyoshi Moon 1989 8. A4 Figure 1, Display of the case Japanese Patent Application No. 1-13352 2, Name of the invention GuiSpring System 3, Person making the amendment Relationship to the case Patent applicant (404) NHK Spring Co., Ltd. 4, Agent Chiyoda, Tokyo 3-7-2-7, Kasumigaseki-ku, page 14, lines 12 to 18 of the statement of contents of the amendment, ``
The bellows 45 traps a predetermined amount of oil. '' has been corrected to the following sentence. The gas is sealed in two stages. That is, the gas is initially supplied to the air chamber 80 at low pressure. When the bellows 45 is bent to a predetermined stroke, the valve body 50 of the self-sealing means 52 comes into close contact with the valve seat 51, thereby closing the flow port 25. For this reason, bellows body 4
6 can no longer be bent in the axial direction. In this way, the valve body 50
After the valve seat 51 comes into close contact with the valve seat 51, the hole 63 is closed by the ball 61 and the screw 62, thereby trapping oil in the gap 92 between the outer peripheral surface of the inner cylinder part 23 and the inner surface of the bellows body 46. Thereafter, high pressure gas is supplied to the air chamber 80.

Claims (3)

[Claims] (1) A plurality of hollow cylinders, a rod inserted into each cylinder so as to be movable in the axial direction, and a rod arranged at a place where each rod penetrates each cylinder to seal the sliding part of the rod. a sealing means, and a bellows having a metal bellows body housed inside each cylinder and expandable and retractable in the axial direction of the cylinder;
A liquid chamber on one side of the space inside the cylinder partitioned by the bellows is filled with liquid, and a liquid chamber on the other side of the space inside the cylinder partitioned off by the bellows is filled with gas at a pressure higher than atmospheric pressure. A die spring system comprising: a sealed air chamber in which gas pressure acts in a direction to push the rod out of the cylinder; and a gas passage that interconnects the air chambers of the plurality of cylinders. (2) A plurality of hollow cylinders, a rod inserted into each cylinder so as to be movable in the axial direction, and a rod arranged at a place where each rod penetrates each cylinder to seal the sliding part of the rod. a sealing means, and a bellows having a metal bellows body housed inside each cylinder and expandable and retractable in the axial direction of the cylinder;
Of the space inside the cylinder partitioned by the bellows, there is a liquid chamber filled with liquid on the side where the sealing means is provided, and a space inside the cylinder partitioned by the bellows that is not provided with the sealing means. an air chamber located on the side that is filled with gas at a pressure higher than atmospheric pressure and whose gas pressure acts in a direction to push the rod out of the cylinder; and a gas passage that interconnects the air chambers of the plurality of cylinders. A die spring system characterized by being equipped with. (3) A liquid passage according to claim 1 or 2, further comprising a liquid passage communicating with each liquid chamber of the plurality of cylinders, and a liquid feeding means capable of replenishing the liquid to the liquid chamber is connected to the liquid passage. die spring system.