JP2017196658A - Device for equalizing pressures applied to die cushion device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To solve a problem in a forming using a die cushion device; in which accuracy differences or deformations in the die cushion device including a cushion pin causes unequal pressures received by a blank holder resulting in formation not conforming to a forming analysis; by equalizing the pressures applied to the blank holder so as to obtain a result conforming to a forming analysis.SOLUTION: A device for equalizing pressures applied to a die cushion device comprises: a pair of a fluid damper and a relief valve. The fluid valve is connected to a fluid piping through the relief valve in the pair, and configured to cause a rise in an internal pressure generated when the fluid damper is compressed, to operate the relief valve so as to select only fluid dampers which apply die cushion pressures to the blank holder, resulting in equalizing the pressures inside the damper.SELECTED DRAWING: Figure 2

Description

  The present invention relates to equalization of a pressing force of a die cushion device of a press machine.

  In molding using a die cushion device of a press machine, in general, a material that is a molded object is constrained between a blank holder and an upper mold to adjust the inflow amount of the material. If the amount of inflow is too large, the quality is poor. This inflow amount is determined by the constraining shape surface as a result of the molding analysis. In the molding analysis, it is assumed that the blank holder receives an equal applied pressure from the die cushion device via the cushion pin.

  The mechanism of the die cushion device will be described. The die cushion device is a huge pneumatic cylinder built into the bed of a press machine and moves vertically. Above the die cushion device, there is a bolster plate for attaching a mold, and the bolster plate is provided with a through hole for a metal rod called a cushion pin. The upper surface of the die cushion device is a plate called a cushion pad, and a lower blank holder is supported from below through a through hole of the bolster plate via a cushion pin arranged on the cushion pad. When the upper die is lowered and the blank holder is pressed, the die cushion device is also pressed through the cushion pin, and the reaction force of the compressed air in the die cushion device becomes the pressure applied to the blank holder by the die cushion device.

  The die cushion device maximizes the pressurization capacity in a narrow installation place, so the weight of the movable part is reduced, and there is a variation in the dimensional accuracy of the cushion pin. large. In addition, in the case of press parts for automobiles, there are many asymmetric parts with respect to the center of the machine, and this offset load also affects, and in many cases, uniform pressurization to the blank holder, which is the premise of molding analysis, has been realized. Absent.

  A usage pattern of the die cushion device will be described. In general, the press machine is positioned as a general-purpose facility, and in order to accommodate a mold that is an unspecified large number of dedicated tools, a cushion pin can be used as a place where a cushion pin can be used. A through hole is provided. On the other hand, the mold which is a dedicated tool uses only about 10 to 30% of a large number of molds with respect to a place where a large number of cushion pins, which are versatile press machines, can be used.

  For equalizing the pressure applied to the blank holder via the cushion pin, a pressure equalizing device (Patent Document 1 and Patent Document 2) using a hydraulic damper (hydraulic spring) has been invented. In both the inventions, the hydraulic dampers are arranged at the usable locations of all the cushion pins on the cushion pad, and the hydraulic chambers of all the hydraulic dampers are connected to the hydraulic piping and also connected to the hydraulic device for leveling. We are trying to compress. In the latter invention (Patent Document 2), a hydraulic device is provided outside the movable portion of the die cushion device, and a high-pressure hydraulic pipe to the movable portion is required in a narrow space. In the former invention (Patent Document 1), hydraulic equipment including a hydraulic pump is disposed in the movable part of the die cushion device, and high-pressure hydraulic piping to the movable part in a narrow space is not necessary. Requires power supply.

WO2004 / 065112 Japanese Patent Laying-Open No. 2005-297021

  In molding using a die cushion device of a press machine, uniform pressurization to the blank holder by the die cushion device, which is a precondition for molding analysis, is realized due to accuracy differences and deformation of the die cushion device including cushion pins Can not. Accordingly, it is an object to equalize the pressure applied to the blank holder, to realize the preconditions of the molding analysis, and to obtain a molding result consistent with the molding analysis.

  A die cushion pressure equalizing device according to the present invention is a pressure equalizing device for a die cushion device configured by a fluid damper and a relief valve as a pair, and the fluid is passed through a relief valve having all the fluid dampers as a pair. When the fluid damper is connected to the pipe and the internal pressure of the fluid damper is increased when the fluid damper is compressed, the corresponding relief valve is activated, and only the compressed fluid damper is connected to the pipe to the fluid pipe. It is characterized by opening.

  The die cushion pressure equalizing apparatus of the present invention uses a relief valve with a pilot to which the pilot mechanism is added to the relief valve described in the previous section, thereby arbitrarily and remotely controlling the pressure to open the pipe to the fluid pipe to be connected. It is characterized by doing.

  The die cushion pressure equalizing apparatus according to the present invention uses an air-driven hydraulic pump in a form in which a hydraulic output proportional to the air pressure of the drive source is obtained in setting the pilot pressure of the relief valve with pilot described in the previous section. By using compressed air branched from the pneumatic chamber of the die cushion device as the drive source of the hydraulic pump, and using the hydraulic output of the air-driven hydraulic pump as the pilot input of the relief valve with pilot described in the previous paragraph, The operating pressure of the relief valve with pilot can automatically follow the die cushion pressure, and an air-driven hydraulic pump with space-saving features is located in the movable part of the die cushion device, thereby reducing the space No piping or wiring to the movable part is required.

  It is possible to realize equalization of the pressure applied to the blank holder of the die cushion device, which is a precondition for the molding analysis, and to match the molding result with the molding analysis result.

  It has a function of automatically selecting a fluid damper compressed by a relief valve, and does not require a larger equipment due to a longer stroke or a compensation hydraulic device.

  By using a relief valve with a pilot to which a pilot function is added as a relief valve for selecting a compressed fluid damper, the operation timing of the relief valve can be controlled arbitrarily and remotely, and versatility is expanded.

  By using the output hydraulic pressure of the air-driven hydraulic pump that uses the compressed air in the pneumatic chamber of the die cushion device as the drive source as the relief valve operation setting, the relief valve activation time is automatically set to the pressure output of the die cushion device. It becomes possible to follow. In addition, the air-driven hydraulic pump device does not require a power source other than compressed air, which is the primary input source, and is compact and space-saving, so it does not require wiring or piping to a movable part in a narrow space. .

It is mechanism explanatory drawing of the die cushion pressure equalization apparatus single item. It is mechanism explanatory drawing at the time of the assembly | attachment of the die cushion pressure equalization apparatus.

  FIG. 1 is a diagram for explaining a single mechanism of a die cushion pressure equalizing apparatus. The die cushion pressure equalizing device (10) includes, as a basic structure, a fluid damper (11) (or a fluid spring, hereinafter referred to as a damper) and a relief valve (12) as a pair. Although FIG. 1 shows a relief valve with a pilot, the pilot function (12a) is for expanding versatility. First, the basic function will be explained with the relief valve (12), and the pilot function (12a) will be described. Will be described later. The damper (11) is located between the die cushion device and the cushion pin. When the cushion pin is pressed together with the blank holder, the damper (11) is compressed, and at this time, the damper (11) is connected to the other dampers (11). This is the main component that equalizes the internal pressure. The relief valve (12) is actuated by an increase in the internal pressure of the damper generated when the pair of dampers (11) is compressed, and only the pair of compressed dampers (11) are interconnected fluid pipes. Open the conduit to. On the other hand, for the damper (11) which is not compressed, the relief valve (12) as a pair does not operate and the pipe is not opened. Therefore, the relief valve (12) has a function of selecting a damper to be used.

  FIG. 2 shows an explanatory view of the mechanism when the die cushion pressure equalizing device (10) is assembled. The die cushion pressure equalizing device (10) is disposed on all cushion pin usable locations on the cushion pad on the upper surface of the die cushion device, and is connected by a fluid pipe (20). When the upper die (26) is lowered and the cushion pin (24) is pressed together with the blank holder (25), the damper (11) at the location where the die cushion function is used is compressed via the cushion pin (24), and the damper The internal pressure rises. The relief valve (12) is set to operate with a slight pressure increase in advance, and only the relief valve (12) which is a pair of the compressed damper (11) is operated, and the damper ( 11) The internal pressure does not increase and the relief valve (12) does not operate. As described above, only the compressed damper (11) at the location where the die cushion device is used opens the pipe to the fluid pipe (20) via the paired relief valve (12) and opens the pipe. The internal pressure, that is, the reaction force of the damper (11) at the place where it is placed is equalized.

  As explained in the above usage pattern of the die cushion device, the majority of molds have a very low damper usage rate, and the damper used is affected by the majority of unused dampers, and the compression rate of the oil inside the damper That is, it takes a long stroke and time to increase the hydraulic pressure. From the usage form of the die cushion device, it is ideal that the die cushion pressure equalizing device is effective immediately after the blank holder is pressed by the upper die, and the lengthening of the stroke is insufficient in terms of function. In addition, the longer stroke requires a cooling device for oil in some cases because the damper device becomes larger and the amount of fluid oil increases. As a method of avoiding a long stroke, there is a method of compensating the hydraulic pressure using an external hydraulic device, which is also used in both of the above-described inventions (Patent Document 1 and Patent Document 2). However, if a function for selecting whether or not to use each fluid (hydraulic) damper is added, the influence of the unused fluid damper can be eliminated, and the compensating hydraulic pressure used in both of the above-described inventions (Patent Document 1 and Patent Document 2). No equipment or longer stroke is required. The present invention realizes equalization of the die cushion pressure without selecting a fluid damper with a simple mechanism using a relief valve and providing a longer stroke or a compensating hydraulic device.

  By using a relief valve with a pilot with a pilot function (12a) added to the relief valve for selection (12), the relief valve (12) is actuated and the timing for opening the pipeline to the fluid pipe (20) is arbitrarily set. Control remotely. In general, the pressure applied to the die cushion is proportional to the stress characteristics (tensile strength), area, and plate thickness of the molded article, and the number of cushion pins used is proportional to the area. However, in recent years, it is possible to cope with the case where high pressurizing force is required in spite of the small area due to the increase in material tension for high tension and light weight to improve the rigidity of the car body, or vice versa. There is a need to. Thus, in order to expand versatility, the operation timing of the relief valve (12) is arbitrarily and remotely controlled using the pilot function (12a) of the present invention.

  In setting the pilot pressure of the pilot relief valve (12) described in the preceding paragraph, an air-driven hydraulic pump device (21) is used which can obtain a hydraulic output proportional to the air pressure of the drive source. The air-driven hydraulic pump (21) is a commercially available Pascal pump (trade name, compressed air is used as the drive source, and the area ratio between the pneumatic piston and the hydraulic piston is used as the pressure increase ratio. The hydraulic output is proportional to the air pressure of the drive source. This is a small-sized pump having a function and configuration similar to those of a small-sized pump that uses compressed air, which is a primary input, as a driving source, and a hydraulic output proportional to the primary input pressure as a secondary output. The compressed air (23) branched from the pneumatic chamber (27) of the die cushion device is connected to the drive source of the air driven hydraulic pump device (21), and the output (22) of the air driven hydraulic pump device (21) is connected. The pilot (12a) operating pressure is used. Thereby, the operation timing of the relief valve with pilot (12) described in the preceding paragraph is automatically caused to follow the pressurization output of the die cushion device. The air-driven hydraulic pump device (21) does not require a power source other than compressed air and is small in size, so it can be attached to the movable part of the die cushion device, and piping to the movable part in a narrow space is also possible. Wiring is also unnecessary.

  The die cushion pressure equalizing device can be applied to a pneumatic die cushion device of a press machine.

10 Die cushion pressure equalization device 11 Fluid damper 12 Relief valve 12a Relief valve pilot mechanism (function)
20 Fluid piping for connection between die cushion pressure equalization devices 21 Air-driven hydraulic pump 22 Pilot piping (air-driven hydraulic pump output)
23 Pneumatic chamber branch piping (Air-driven hydraulic pump primary input)
24 Cushion pin 25 Blank holder (mold)
26 Upper mold (mold)
27 Die cushion pneumatic chamber 28 Bolster plate 28a Cushion pin through hole

Claims (3)

  A fluid damper and a relief valve are configured as a pair, and all the fluid dampers are connected to the fluid piping through the pair of relief valves, and the internal pressure of the damper is increased when the fluid damper is compressed. A die cushion pressure equalizing device, wherein a relief valve is actuated and only a compressed fluid damper is opened to open a fluid pipe.   2. The die cushion pressure according to claim 1, wherein a pressure for opening a pipe line to a fluid pipe to be connected is arbitrarily and remotely controlled by using a relief valve with a pilot having a pilot mechanism added to the relief valve. Equalizing device.   In setting the pilot pressure of the relief valve with pilot, an air-driven hydraulic pump is used that can obtain a hydraulic output proportional to the air pressure of the drive source, and the air-driven hydraulic pump is driven from the pneumatic chamber of the die cushion device. By using the branched compressed air and using the hydraulic output of the air-driven hydraulic pump as the pilot input of the pilot relief valve, the operating pressure of the pilot relief valve automatically follows the die cushion pressure. The die cushion pressure equalizing apparatus according to claim 2, wherein

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