JPH0622816B2 - Vertical press machine for plastic molding - Google Patents

Description

TECHNICAL FIELD The present invention relates to a vertical press device for plastic molding.

[Conventional technology]

Conventionally, there is known a vertical press device for molding SMC (Sheet Molding Compound) and other plastic products, which is an up-press type that moves an upper mold up and down. An example of this type of press device is disclosed in Japanese Patent Publication No. 1-38651. In this vertical press device, a fixed plate (lower part of the press body) and a movable plate (slide) are vertically arranged, and the movable plate is moved vertically by a mold opening / closing cylinder (lift cylinder device) to clamp the mold. A vertical mold clamping device of a molding machine, which applies a mold clamping force to a mold by a cylinder (main cylinder device), comprising a balance cylinder provided between a fixed platen and a movable platen, and a piston. It has an accumulator having a divided oil chamber and a gas chamber, and an oil passage connecting the oil chamber of the balance cylinder and the oil chamber of the accumulator, and the volume of the gas chamber of the accumulator according to the stroke of the piston of the balance cylinder. Of the balance cylinder, the relationship between the pressure receiving area of the piston of the balance cylinder, the pressure receiving area of the piston of the accumulator, and the gas pressure of the gas chamber is variable. In the mold opening and closing stroke lowering limit, the weight of the entire movable part to move is set to satisfy the relationship as by connexion supported balance cylinder with a movable platen.

[Problems to be Solved by the Invention]

However, in such a conventional vertical press machine for plastic molding, the ascent and return operation of the movable platen is made up of a balance cylinder composed of a plurality of lift cylinders and a balance cylinder connected to an accumulator that does not have a variable set pressure function. Since it is performed by the system system, there is a problem that the movable platen is not ideally raised and returned.

In other words, the vertical press machine for plastic molding has the characteristic that the weight of the mold fluctuates greatly with the replacement of the mold, and recently, with the development of molding materials, it is required to shorten the molding time and the movable platen is lowered. In addition, a higher ascending speed is required. Therefore, it is difficult to increase the speed of the ascent / return shift of the movable plate in response to the variation of the die weight, with the pressing power determined by the product of the pressing force and the pressing speed being constant.
The pressure adjustment of the balance system system generally needs to be set to a pressure at which the required descending speed can be secured in the mold having the minimum weight, and the burden rate of the balance system system cannot be increased so much. Therefore, as the weight of the mold becomes heavier, the load ratio of the lift cylinder increases by the increase of the weight of the mold, and the load of the electric motor increases at the time of returning from the ascent. Moreover, due to the increase of the burden rate, there is a possibility that a shock occurs, the durability of the press machine is deteriorated, and the original performance of the press cannot be exhibited early.

[Means for Solving the Problems]

The present invention has been made in view of the above-mentioned conventional technical problems, and the configuration thereof includes a hydraulic pump device, a press body, a lower die fixed to the lower portion of the press body, and the press body. A slide vertically movably arranged in the middle part of the press, an upper die fixed to the slide, and a slide provided between the upper part of the press main body and the slide and supplying pressure oil from the hydraulic pump device. And a main cylinder device that drives the slide downward, and a lift that is arranged between the upper or lower part of the press body and the slide, and that is supplied with pressure oil from the hydraulic pump device and drives the slide upward. A vertical press device for plastic molding, which has a cylinder device and is formed by inserting a plastic molding material between the upper mold and the lower mold, and is arranged between the lower part of the press body and the slide. Set up, slide up A balance cylinder device to be driven, an accumulator in which a hydraulic chamber is connected to the balance cylinder device, a relief valve of a preset pressure variable type for adjusting the pressure of the hydraulic chamber of the accumulator, and pressure oil from the hydraulic pump device are A vertical press device for plastic molding, which includes an opening / closing valve that supplies the hydraulic chamber of the accumulator at a pressurizing position and holds the hydraulic chamber at a pressure maintaining position.

And the balance cylinder device can slide,
It can be set so as to support 50 to 70% of the static load of the moving member such as the upper mold. It is also possible to provide a pressure detector for detecting the pressure of the lift cylinder device.

[Action]

In the plastic molding vertical press apparatus having such a configuration, first, the pressure of the accumulator is adjusted when the lower die and the upper die are changed, especially when the upper die having a different weight is changed. This adjustment work is performed as follows, for example. The pressure oil from the hydraulic pump device is drained from the main cylinder device, the slide is raised to the upper limit position to open the upper mold and lower mold, and the balance cylinder device is operated forward to operate the accumulator hydraulic chamber as the reference pressure. To Then, the set pressure of the relief valve is adjusted to an appropriate value according to the weight of the replaced upper mold, and the open / close valve is set to the pressurizing position. As a result, the hydraulic pressure of the hydraulic pump device is supplied to the hydraulic chamber of the accumulator, and the pressure of the accumulator is adjusted to an appropriate value that matches the weight of the replaced upper die, that is, the static load of the moving member.

Since this proper value is affected by the slide driving force of the lift cylinder device, when the pressure detector is provided, it can be corrected based on the value detected by the pressure detector. That is, the pressure oil of the hydraulic pump device is supplied to the lift cylinder device, and the oil pressure acting on the lift cylinder device having a constant pressure receiving area is detected by the pressure detector.

When an appropriate value is stored in the accumulator, the on-off valve is switched to the pressure holding position to hold the hydraulic chamber of the accumulator.

After such setting is completed, the molding operation of the plastic product is performed. At the start of molding of SMC and other plastic products, the slide rises to form a gap between the upper mold and the lower mold. In this state, a thermosetting plastic molding material or the like is put in the lower mold, pressure oil from the hydraulic pump device is supplied to the main cylinder device, the slide is driven downward, and the pressure oil in the lift cylinder device is drained. . At the same time, the pressure oil in the balance cylinder device returns to the hydraulic chamber of the accumulator as the slide is lowered. Since the accumulator stores an appropriate value according to the weight of the upper die, the time required for the slide to descend is
The weight of the upper mold is shortened to a constant value regardless of the size. Then, the plastic molding material is molded between the upper mold and the lower mold. After that, the upper and lower molds are opened and the molded product is taken out.

At the time of this mold opening, the pressure oil from the hydraulic pump device is supplied to the lift cylinder device, and the slide is raised and returned while draining the pressure oil of the main cylinder device. At that time, the rising and returning of the slide is assisted by the balance cylinder device. That is, the pressure oil accumulated in the hydraulic chamber of the accumulator is supplied to the balance cylinder device to drive the slide upward. As a result, the power required to return the slide up is maintained substantially constant regardless of the weight of the upper die.

When the upper and lower dies are opened and closed, the moving members such as slides and upper dies move rapidly, but the moving members are elastically supported by the accumulator at an appropriate pressure. The shock caused by the movement is reduced, and the loosening of each part of the press device is effectively prevented.

By the way, the lift driving force of the sillide by the balance cylinder device supports 50 to 70%, preferably about 60%, of the static load of the moving member composed of the slide, the upper mold, etc. at the maximum lower limit position of the slide. It is desirable to set. As a result, the influence of the static load of the moving member becomes almost constant, and the mold closing force can be applied relatively finely. In addition, the main cylinder device, the lift cylinder device, and the balance cylinder device are installed in the press body without difficulty, and the slide is quickly returned to the operation while ensuring the required pressing force and pressurizing speed by the main cylinder device. You can Further, since the lift return force of the slide is given not only by the balance cylinder device but also by the lift cylinder device, when the pressure detector is provided, the pressure supplied from the hydraulic pump device is supplied to the lift cylinder device. The pressure of the oil can be monitored by a pressure detector to know the suitability of the pressure of the accumulator. If the pressure of the accumulator is improper, the accumulator pressure adjustment work described above is performed to give a proper value.

〔Example〕

Hereinafter, embodiments of the present invention will be described with reference to the drawings.

1 and 2 show a vertical press machine for plastic molding.
An example is shown. In the drawings, reference numeral 1 indicates a press body, and a slide 2 is installed on the press body 1 so as to be vertically movable and the vertical movement is guided to a column 1a which is an intermediate portion of the press body 1. . A main cylinder device 3 for lowering and driving the slide 2 is provided on the upper part of the press body 1, and a piston member 3 a protruding from the slide 2 is provided.
Is slidably fitted in the main cylinder 3b fixed to the press body 1.

Pressure oil is supplied to the main cylinder device 3 from a hydraulic pump device 4 including a pair of variable displacement hydraulic pumps through an oil passage 5, and the first solenoid valve 6 is provided in the oil passage 5. Is intervening. The first solenoid valve 6 has a pressurizing position a, a pressure holding position b, and a depressurizing position c, and by adopting the pressurizing position a, the pressure oil from the hydraulic pump device 4 is supplied to the main cylinder device 3. , The pressure in the main cylinder device 3 is maintained by adopting the pressure holding position b, and the main cylinder device 3 is adopted by adopting the pressure reducing position c.
The pressure oil inside is drained to the reservoir 7.

A plurality of lift cylinder devices 8 for driving the slide 2 to rise are interposed between the upper portion of the press body 1 and the slide 2. The lift cylinder device 8 includes a cylinder 8a fixed to four corners of the press body 1, and a cylinder 8a.
A piston 8c slidably fitted to the piston rod 8b and having a lower end portion of the piston rod 8b connected to the slide 2. Through each of the cylinders 8a, an oil passage 9 from the hydraulic pump device 4 to the second solenoid valve 10 is provided. Pressure oil is being supplied. The second solenoid valve 10 supplies the pressure oil of the hydraulic pump device 4 to each cylinder 8a by setting the pressurization position a, and each cylinder 8 by setting the pressure holding position b.
The pressure in a is held, and the pressure oil in each cylinder 8a is drained to the reservoir 7 by setting the reduced pressure position c. Reference numeral 16 is a pressure detector provided in the oil passage 9, and detects the pressure of the pressure oil supplied from the hydraulic pump device 4 to the lift cylinder device 8 and the pressure supporting the weight of the movable portion during the pressure retention. be able to. A lower die 11 is fixed to the lower portion of the press body 1 and an upper die 12 facing the lower die 11 is fixedly provided on the lower surface of the slide 2. The lift cylinder device 8 is arranged between the slide 2 and the upper part of the press body 1 so as to pull up the slide 2, but the lift cylinder device 8 is arranged between the slide 2 and the lower part of the press body 1. It is also possible to arrange it between the two and to push up the slide 2.

Next, a plurality of balance cylinder devices 13 are interposed between the lower part of the press body 1 and the slide 2. The balance cylinder device 13 includes a silaneda 13a fixed to the four corners of the press body 1 and a piston member 13b having an upper end coupled to the slide 2. Each cylinder 13a has an oil passage 1a.
4 is connected to the hydraulic chamber 15a of the accumulator 15 so that the pressure oil accumulated in the gas compression type (nitrogen gas-filled) accumulator 15 is constantly operating.

The oil passage 14 connecting each cylinder 13a and the hydraulic chamber 15a of the accumulator 15 is formed by an oil passage 18 having a third solenoid valve 17 which is an opening / closing valve having a pressurizing position a and a pressure holding position b. Then, it is connected to the oil passage 9 upstream of the second solenoid valve 10. Therefore, by making the third solenoid valve 17 take the pressurization position a, the pressure oil of the hydraulic pump device 4 is supplied to the accumulator 15 side regardless of the switching position of the second solenoid valve 10, and the pressure holding position b. The pressure on the accumulator 15 side is maintained by taking Further, in the oil passage 14 connecting each cylinder 13a and the accumulator 15, a set pressure variable type electromagnetic relief valve 19 is provided.
Is connected so that the pressure in the hydraulic chamber 15a of the accumulator 15 can be adjusted to a predetermined value.

Next, the operation will be described.

First, when the lower die 11 and the upper die 12 are changed, particularly when the upper die 12 having a different weight is changed, the hydraulic chamber 1 of the accumulator 15 is changed.
Adjust the pressure at 5a. This adjustment work is performed as follows. The second solenoid valve 10 is set to the pressurization position a to supply the pressure oil of the hydraulic pump device 4 to each cylinder 8a, and the oil pressure acting on each cylinder 8a is detected by the pressure detector 16. The pressurizing position a is set to the first solenoid valve 6, and the slide 2
Is lowered to the lower limit position to bring the upper mold 12 and the lower mold 11 into close contact with each other, and at the same time, the piston member 13b is fitted into the cylinder 13a to bring the hydraulic chamber 15a of the accumulator 15 to the maximum pressure. The upper die 12 in which the set pressure of the electromagnetic relief valve 19 is exchanged while considering the value detected by the pressure detector 16.
The weight is adjusted to an appropriate value according to the static load of the moving member, and the third solenoid valve 17 is made to adopt the pressurization position a. As a result, the pressure oil of the hydraulic pump device 4 is supplied to the hydraulic chamber 15a of the accumulator 15, and the pressure of the accumulator 15 is adjusted to an appropriate value that matches the weight of the replaced upper die 12.
If an appropriate value is accumulated in the accumulator 15, the third solenoid valve 17 is switched to the pressure holding position b, and the hydraulic chamber 15a of the accumulator 15 is pressure-held.

After such pressure setting is made, the molding operation of the plastic product is performed. At the time of starting the molding of SMC and other plastic products, the slide 2 rises to form a gap between the upper mold 12 and the lower mold 11. In this state, a thermosetting plastic molding material or the like is put into the lower mold 11 to cause the first solenoid valve 6 to take the pressurizing position a and the second solenoid valve 10 to take the depressurizing position c. As a result, as shown in FIG. 1, the pressure oil from the hydraulic pump device 4 is supplied to the main cylinder device 3 through the oil passage 5, the slide 2 is driven downward, and the pressure oil in each lift cylinder device 8 is changed. It is drained to the reservoir 7. At the same time, as the slide 2 is driven downward, the pressure oil in each balance cylinder device 13 is transferred to the oil passage 1.
4 to return to the hydraulic chamber 15a of the accumulator 15. Since an appropriate value according to the weight of the upper die 12 is accumulated in the accumulator 15, the time required for the slide 2 to descend is shortened to a substantially constant value regardless of the weight of the upper die 12. Then, the plastic molding material is heated and pressed between the upper mold 12 and the lower mold 11 to be softened, and is molded in a fluidized state. After reaching the curing temperature, it is cured. At that time, the first solenoid valve 6 is set to the holding pressure position b, and after a predetermined curing time has elapsed, the upper mold 12 and the lower mold 11 are opened and the molded product is taken out.

At the time of opening the mold, as shown in FIG. 2, the first solenoid valve 6 is set to the depressurization position c and the second solenoid valve 10 is set to the pressurization position a so that the pressure oil from the hydraulic pump device 4 is released. It is supplied into each lift cylinder device 8 and is supplied to the main cylinder device 3
The slide 2 is returned to the elevated position while draining the pressure oil of (3) to the reservoir 7. At this time, the balance cylinder device 13 assists the slide 2 in the ascending return. That is,
The pressure oil accumulated in the hydraulic chamber 15a of the accumulator 15 is supplied to the balance cylinder device 13 through the oil passage 14 to drive the slide 2 upward. As a result, the time required for the slide 2 to rise and return is shortened to a substantially constant value regardless of the weight of the upper die 12.

When the upper die 12 and the lower die 11 are opened and closed, the moving member including the slide 2 and the upper die 12 rapidly moves, but the moving member is an accumulator 15 having an appropriate value according to the weight of the upper die 12.
By virtue of the fact that it is elastically supported by the above, the shock caused by the movement of the moving member is satisfactorily reduced, and the loosening of each part of the pressing device is prevented.

By the way, the slide 2 by the balance cylinder device 13
The ascending driving force is set so as to support 50 to 70%, preferably about 60% of the static load of the moving member including the slide 2 and the upper die 12 at the lower limit position of the slide 2 that maximizes. desired. As a result, the influence of the static load of the moving member becomes substantially constant, and for example, the mold closing force can be applied precisely. Further, the main cylinder device 3, the plurality of lift cylinder devices 8 and the balance cylinder device 13 are arranged in the press body 1 without difficulty, and the main cylinder device 3 slides while securing the required pressing force and pressurizing speed. 2 can be promptly raised and returned. In addition, since the lift return force of the slide 2 is given not only by the balance cylinder device 13 but also by a plurality of lift cylinder devices 8, the lift pump device 4 has a constant pressure receiving area from the hydraulic pump device 4. The pressure of the supplied pressure oil can be monitored by the pressure detector 16, and the adequacy of the pressure of the accumulator 15 can be known. When the pressure of the accumulator 15 is inappropriate, the pressure adjustment work of the accumulator 15 described above is performed to give a proper value.

〔The invention's effect〕

As can be understood from the above description, according to the present invention, in the vertical press device for plastic molding capable of moving with a relatively small driving force, a hydraulic pump device having a relatively low capacity is provided. Therefore, it is possible to favorably achieve both the required pressurizing force and pressurizing speed by the main cylinder device and the quick slide return operation. Such compatibility can be obtained very well because the pressure of the accumulator can be adjusted to an appropriate value in response to the weight change due to the change of the upper die, and the time cycle of press working can be effectively shortened. It has the remarkable effect of being economical.

[Brief description of drawings]

1 and 2 show one embodiment of the present invention, FIG. 1 is a partial cross-sectional view of a vertical molding apparatus for plastic molding, and FIG. 1: press body, 2: slide (moving member), 3: main cylinder device, 4: hydraulic pump device, 6: first solenoid valve, 8: lift cylinder device, 10: second solenoid valve, 1
1: lower mold, 12: upper mold (moving member), 13: balance cylinder device, 5, 9, 14, 18: oil passage, 15: accumulator, 15a: hydraulic chamber, 16: pressure detector, 17:
Third solenoid valve (open / close valve), 19: electromagnetic relief valve (relief valve), a: pressurizing position, b: pressure holding position.

Claims (3)

[Claims] 1. A hydraulic pump device, a press body, a lower die fixed to a lower portion of the press body, a slide vertically movable in an intermediate portion of the press body, and fixed to the slide. An upper die, a main cylinder device which is arranged between the upper part of the press body and the slide, and which is supplied with pressure oil from the hydraulic pump device to drive the slide downward, and an upper part or a lower part of the press body. And between the slide and the slide,
A vertical cylinder for plastics molding, which has a lift cylinder device which is supplied with pressure oil from the hydraulic pump device to drive the slide upward, and in which a plastics molding material is inserted between the upper mold and the lower mold. A press device comprising: a balance cylinder device which is disposed between a lower part of the press body and the slide and drives the slide to rise; an accumulator having a hydraulic chamber connected to the balance cylinder device; and an oil pressure of the accumulator. A relief valve of a set pressure variable type for adjusting the pressure of the chamber, and an on-off valve for supplying pressure oil from the hydraulic pump device to the hydraulic chamber of the accumulator at the pressurization position and holding it at the pressure holding position are provided. A vertical press machine for plastic molding, which is characterized in that 2. The vertical press device for plastic molding according to claim 1, wherein the balance cylinder device supports a maximum of 50 to 70% of the static load of a moving member composed of a slide, an upper mold and the like. 3. The vertical molding device for plastic molding according to claim 1, further comprising a pressure detector for detecting the pressure of the lift cylinder device.