JPH0639865A - Hydraulic press - Google Patents

Abstract

PURPOSE:To exclude the mutual effect of the control of a pressure cylinder and the control of a leveling cylinder. CONSTITUTION:A hydraulic press is equipped with the bed 1 to which a lower mold 12 is attached, the freely vertically movable slider 6 to which an upper mold 11 is attached, the main cylinder 4 downwardly moving the slide 6, a servo pump P1 supplying hydraulic oil to the main cylinder 4, the pressure control valve provided to the hydraulic circuit 36 between the servo motor P1 and the main cylinder 4 and a control means 28 controlling the servo pump in order to control the moving speed of the slider 6 and controlling the pressure control valve in order to control the pressing force of the upper mold 11.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a hydraulic press for compression molding a work piece.

[0002]

2. Description of the Related Art Hydraulic presses in which a slide is moved by a hydraulic cylinder and a work piece is compression-molded are well known. There are various types of hydraulic presses according to the material and shape of the workpiece. Car front panel, body panel, etc.
SMC (Sheet Moliding) which is a thermosetting sheet material
In the case of molding with Compound), for example, JP-A-60-15119
The hydraulic press described in Japanese Patent Laid-Open Publication was used.

This conventional hydraulic press has a base, an upright installed upright on the base, a crown provided on the upper part of the upright, a hydraulic cylinder provided on the crown, and a rod lower end of the hydraulic cylinder. A slide supported and guided by the upright to move up and down, a lower mold is fixed to the upper surface of the base, an upper mold is fixed to the lower surface of the slide, and a resin is held in a cavity between the upper and lower molds. It was to be compression molded.

Then, hydraulic oil is supplied to the hydraulic cylinder from a hydraulic pump via a speed / pressure setter, and the speed and pressure are adjusted.

[0005]

In the conventional hydraulic press described above, since the flow rate or pressure of the hydraulic oil from the hydraulic pump having a constant discharge amount is controlled through the speed / pressure setting device, the speed control and the pressure control are not performed. The accuracy was a step ahead.
Therefore, an object of the present invention is to provide a hydraulic press that can perform speed control and pressure control with high accuracy.

[0006]

In order to achieve the above object, the present invention takes the following means. That is, a feature of the present invention is that a bed to which a lower mold is attached, a vertically movable slide to which an upper mold is attached, a main cylinder that moves the slide downward, and a hydraulic oil is supplied to the main cylinder. Servo pump, a pressure control valve interposed in a hydraulic circuit between the servo pump and the main cylinder, the servo pump to control the moving speed of the slide, and the pressing force of the upper mold. And a control means for controlling the pressure control valve for controlling.

[0007]

According to the present invention, the work is filled between the upper and lower molds that have been opened, the slide is lowered by the main cylinder to clamp the upper and lower molds, and the work is compression-molded. . The movement of the main cylinder until the mold clamping is speed controlled, and the pressure is controlled at the time of pressurization.

The speed control is performed by controlling the discharge amount of the servo pump by the control means. The pressure control is performed by controlling the pressure control valve by the control means while keeping the discharge amount of the servo pump constant. Therefore, speed control and pressure control are performed with high accuracy.

[0009]

Embodiments of the present invention will be described below with reference to the drawings. 1 shows a hydraulic press for SMC,
Bed 1 fixed to the floor, uprights 2 standing on the four corners of bed 1, and these 4 uprights 2
And a crown 3 for connecting and fixing the upper end of the. A single-acting main cylinder 4 is attached to the center of the crown 3, a piston rod 5 of the main cylinder 4 projects below the crown 3, and a slide 6 is connected to the lower end of the piston rod 5. The slide 6 is guided by the four uprights 2 and is vertically movable. In addition, double-acting sub-cylinders are provided on both the left and right sides of the crown 3.
7 and the piston rod 8 of this subcylinder 7
Are connected to slide 6.

Leveling cylinders 9 are provided at four corners of the bed 1, and a piston rod 10 of the cylinder 9 is provided.
The upper end face of the slide contact the lower face of the slide 6 so that it can freely come into contact with and separate from. An upper mold 11 is removably attached to the lower surface of the slide 6, and a lower mold 12 is removably attached to the upper surface of the bed 1. The upper and lower molds 11 and 12 are configured so that when they are clamped, a cavity 13 is formed at the mating portion between them, and the lower mold 12 has a mold pressure sensor 14 for detecting the pressure in the cavity 13. Is built in.

A rotary encoder is provided on the side surface of the bed 1.
15 is mounted, and a chain 18 is wound between a sprocket 16 mounted on the input shaft of the encoder 15 and a sprocket 17 rotatably mounted on the side surface of the crown 3, Both ends are locked to a bracket 19 attached to the slide 6. Thus, the encoder 15 detects the position and moving speed of the slide 6.

An oil tank 20 is placed on the crown 3, and the oil tank 20 and the main cylinder 4 are connected via a full oil valve 21. Furthermore, the main cylinder 4
The sub cylinder 7 is connected to the pressurizing cylinder hydraulic unit 25 via hydraulic pipes 22, 23, 24. The leveling cylinder 9 is connected to a leveling hydraulic unit 27 via a hydraulic pipe 26. The pressurizing cylinder hydraulic unit 25, the leveling hydraulic unit 27, the mold pressure sensor 14, and the rotary encoder 15 are electrically connected to the control means 28.

Reference numeral 29 is a die loading / unloading table. FIG. 2 is a hydraulic circuit diagram in the hydraulic unit 25 for the pressurizing cylinder. In the figure, reference numeral 30 is an oil tank, and M1 and M2 are first and second motors for driving a hydraulic pump. The first motor M1 has two speed control first and second motors.
The servo pumps P1 and P2 are driven, and the second motor M2 drives the third and fourth hydraulic pumps P3 and P4 and the servo hydraulic pump P5.

The discharge ports of the first to fourth pumps (P1 to P4) are connected to the first to fourth hydraulic lines 31,32,33,34, respectively. The 1st-4th hydraulic lines 31, 32, 33, 34 are the 5th hydraulic lines
The fifth hydraulic line 35 branches into the sixth and seventh hydraulic lines 36, 37. The sixth hydraulic line 36 branches into the hydraulic pipe 22 connected to the main cylinder 4 and the hydraulic pipe 23 connected to the head side of the sub cylinder 7. The seventh hydraulic line 37 is connected to the sub cylinder 7
Is connected to the hydraulic pipe 24 connected to the rod side. The pilot hydraulic pipe 38 connected to the discharge port of the servo hydraulic pump P5 is shown by a dotted line in the drawing.

Remotely operated relief valves 39, 40, 41, 42 are interposed in the first to fourth hydraulic lines 31, 32, 33, 34, respectively, and each relief valve 39, 40, 41, 42 is connected to a drain line 43. It is connected to the. A cooler 44 is interposed in the drain line 43.
The sixth hydraulic line 36 includes first to third on / off valves 45, 46,
47 are intervening. The first on / off valve 45 opens and closes the sixth hydraulic line 36. The second on / off valve 46 is the sixth
Open the hydraulic line 36 to the oil tank 30. 3rd on
The off valve 47 opens and closes the main cylinder pipe 22. Each of these on / off valves 45, 46, 47 is operated by the hydraulic pressure of the pilot hydraulic pipe 38. This operation is performed by a command from the control means 28.

A pressure control valve 48 is interposed in a sixth hydraulic line 36 between the first on / off valve 45 and the third on / off valve 47. The pressure control valve 48 can change its set pressure steplessly or stepwise by a command from the control means 28. Fourth to sixth on / off valves 49, 50 and 51 are also interposed in the seventh hydraulic line 37. On each of these
The off valves 49, 50, 51 are also opened / closed by a command from the control means 28.

A check valve 52 is built in the full oil valve 21, and the check valve 52 is turned on and off by the hydraulic pressure of the pilot hydraulic pipe 38. This operation is also the control means 28
It is performed by the command of. FIG. 3 is a hydraulic circuit diagram of the leveling hydraulic unit 27. The hydraulic oil in the oil tank 53 is connected to the hydraulic pipe 26 connected to the leveling cylinder 9 through the hydraulic pump P6 and the eighth hydraulic line 54. There is. A servo valve 55 is interposed in the eighth hydraulic line 54,
The servo valve 55 is operated by a command from the control means 28. Four servo valves 55 are provided corresponding to each leveling cylinder 9.

FIG. 4 is an operation flow chart of the hydraulic press having the above-mentioned structure, and FIG. 5 is an operation diagram thereof. In these drawings, STEP 1 is slide 6
Indicates the start time when is at the top dead center position. In this state, the cavity 13 of the lower mold 12 is filled with the SMC material 56.

Next, STEP 2 shows a state in which the slide 6 descends at a high speed. At this time, in the hydraulic circuit diagram of FIG. 2, the hydraulic oil from the first to fourth pumps P1, P2, P3, P4 is
To the fourth hydraulic line 31, 32, 33, 34 and the fifth hydraulic line 35, and from the sixth hydraulic line 36 to the main cylinder 4 and the sub-cylinder 7 through the hydraulic pipes 22 and 23, to the main cylinder 4 and the sub cylinder. Supplied to cylinder 7. At this time, the first, third, fifth, and sixth on / off valves 45, 47, 50, 51 are open, and the second and fourth on / off valves 46, 49 are closed. At this time, the oil on the rod side of the sub-cylinder 7 is returned to the tank 30 through the fifth on / off valve 50.

Step 3 shows the slide 6 in the middle speed lowering state, and controls the discharge amount of the speed control servo pumps P1 and P2.
The lowering speed of the slide 6 is set to the medium speed by controlling by. The switching from STEP 2 to STEP 3 is performed based on the position detection of the slide 6 by the rotary encoder 15. In STEP 4, speed control and leveling control are performed simultaneously. That is, STEP 3 is switched to STEP 4 based on the position detection of the slide 6 by the rotary encoder 15. At this time, the lower surface of the slide 6 is at the leveling cylinder.
Make a soft touch to the upper end of rod 10 of 9. After that, the slide 6 descends while pressing the rod 10 of the leveling cylinder 9. In this leveling cylinder 9, each servo valve 55 is controlled so that all four cylinders have the same level,
The levelness of 6 is maintained with high precision.

In STEP 4, the speed control servo pumps P1 and P2 are controlled, and the descending speed of the slide 6 is controlled in multiple stages. At the end of this STEP 4, the upper die 11 and the lower die 12 are clamped, and the SMC material 56 in the cavity 13 is finished.
Fills the cavity 13. SMC in the cavity 13
When the material 56 is filled, the internal pressure of the cavity 13 has a peak value as shown in FIG. The mold pressure is detected by the mold pressure sensor 14. When this detected value and the preset setting value match, the speed control is switched to the next pressure control. This control switching is shown in STEP5.

STEP 6 shows a state in which the pressure control and the leveling control are simultaneously performed. That is, the discharge amount from the hydraulic pump is made constant, and the pressure in the hydraulic circuit is controlled by the pressure control valve 48. This pressure control is performed by the SM inside the cavity 13.
The die pressure sensor 14 detects the state change of the C material 56, and the applied pressure is controlled in multiple steps (including stepless steps) in response to the state change. This control command is given by the control means 28.

In the multi-stage pressure control, when the state change of the SMC material 56 in the cavity 13 due to the passage of time is known in advance, the preset set pressure is set every predetermined time. It is also achieved by controlling in multiple stages. In the pressure control, the leveling cylinder 9 is controlled according to the pressure change of the main cylinder 4 and the sub cylinder 7, and keeps the slide 6 horizontal.

When the compression molding is completed, the slide 6 is slightly moved up through the depressurization process, and the in-mold coating is performed. This step is shown in STEP 7. In this STEP 7, the speed is controlled by the servo valve 55. When this slide is raised, the second, third, fifth,
OFF valves 46, 47, 50 are closed, and first, fourth, sixth ON / OFF valves
45,49,51 are opened. Then, the hydraulic oil is supplied from the fifth hydraulic line 35 through the sixth and seventh hydraulic lines 36, 37 to the cylinder side and the rod side of the sub-cylinder 7,
Sub-cylinder 7 becomes free. Main cylinder 4
This oil can flow into the oil tank 20 through the full oil valve 21 by operating the check valve 52 with pilot pressure.

Then, by raising the leveling cylinder 9 via the servo valve 55 of the level cylinder 9,
Slide 6 is raised. Even when the slide 6 is raised, the leveling cylinder 9 is controlled and the slide 6 is raised while maintaining the horizontal state. The rising speed and position of the slide 6 are detected by the rotary encoder 15 and fed back to the speed control.

When the in-mold coating is completed, the slide 6 descends again, and when it reaches a predetermined position, the speed control is switched to the pressure control. This switching is also performed based on the pressure detected by the mold pressure sensor 14. This step is shown in STEP 8. In STEP 8, multi-stage pressure control similar to that in STEP 6 is performed, and compression molding including in-mold coating is completed. Then, after depressurizing, slide 6
To the original top dead center. This ascending process is shown after STEP 9, and the speed is controlled after STEP 9. When the slide is raised after STEP 9, the first, third and fifth on / off valves 45, 47 and 50 are closed and the second, fourth and sixth on / off valves 46, 49 and 51 are opened. Then, the hydraulic oil is supplied from the fifth hydraulic line 35 to the seventh hydraulic line 37 to the rod side of the sub-cylinder 7. The oil on the cylinder head side of the sub-cylinder 7 is the sixth hydraulic line.
The oil in the main cylinder 4 is returned to the tank 30 through the second on / off valve 46 of 36, and the oil in the main cylinder 4 is operated through the full oil valve 21 by operating the check valve 52 with the pilot pressure.
Returned to.

Then, all steps of the hydraulic press are completed. The present invention is not limited to the above-described embodiment, and for example, it is possible to detect the state change of the material in the mold by the change of the hydraulic pressure of the main cylinder and control the applied pressure in multiple stages. Is. Further, although the position of the slide is detected by the encoder, it may be detected by a limit switch or the like. Further, the pressure control valve may be a multi-step control using a plurality of control valves having different set pressures.

[0028]

According to the present invention, since the speed control of the main cylinder is performed by the servo pump and the pressure control is performed by the pressure control valve, highly accurate control is possible.

[Brief description of drawings]

FIG. 1 is a partial sectional front view of a hydraulic press showing an embodiment of the present invention.

FIG. 2 is a hydraulic circuit diagram of a main cylinder.

FIG. 3 is a hydraulic circuit diagram of a leveling cylinder.

FIG. 4 is an operation flowchart of the hydraulic press according to the embodiment of this invention.

FIG. 5 is an operation diagram showing an embodiment of multi-stage pressure control of the present invention.

FIG. 6 is a graph showing in-mold pressure.

[Explanation of symbols]

 1 bed 4 main cylinder 6 slide 9 leveling cylinder 11 upper mold 12 lower mold 28 control means 48 pressure control valve 55 servo valve P1 servo pump P6 hydraulic pump

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁵ Identification number Office reference number FI technical display location B29L 31:30 4F (72) Inventor Kazuyuki Kajiyama 1 and 4 of 169 Okubo, Okubo-cho, Akashi-shi, Hyogo 201 (72) Inventor Koji Ueda 7-2, Kikusui-cho, Hyogo-ku, Kobe-shi, Hyogo (72) Inventor Tokuji Nakagawa 12-24, Kori-Minamino-cho, Neyagawa-shi, Osaka (72) Inventor Naoki Takeuchi Kobe-shi, Hyogo No. 907, 6-14 D, Nakamachi, Minatoshima, Chuo-ku (72) Inventor Hiroaki Kondo 4-12, Tsuruga 4-chome, Nada-ku, Kobe-shi, Hyogo

Claims (1)

[Claims] 1. A bed (1) for mounting a lower mold (12), a vertically movable slide (6) for mounting an upper mold (11), and a main cylinder () for moving the slide (6) downward. Four)
And a servo pump that supplies hydraulic oil to the main cylinder (4)
(P1) and the hydraulic circuit between the servo pump (P1) and the main cylinder (4)
The pressure control valve (48) interposed in (36), the servo pump (P1) is controlled to control the moving speed of the slide (6), and the pressing force of the upper mold (11) is controlled. A hydraulic press comprising: a control means (28) for controlling the pressure control valve (48) to be controlled.