JPH1147839A - Counter liquid pressure die set - Google Patents

Abstract

PROBLEM TO BE SOLVED: To make it possible to execute both of counter liquid pressure forming and ordinary forming with a universal type press machine by making a counter liquid pressure die set, which has a pressure reducing part for generating a back pressure on a forming material and a hold-down part for generating the force to hold down the forming material, attachable and detachable to and from the universal type press machine. SOLUTION: A liquid pressure control unit 31 sucks working fluid from a working fluid tank 42 by a working fluid supplying pump 41 and supplies the working fluid via a selector valve 44 and a check valve 50 to a liquid pressure chamber 12. When this liquid pressure chamber 12 is filled with the working fluid, the selector valve 44 is closed in accordance with a fill detection signal. A board hold-down force control unit 32 supplies the working fluid to a board hold-down cylinder 10 and controls the blank hold-down force on the forming material 22. When a slide 4 exists at an ascending end, the working fluid is sucked via a filter 63 from a working fluid tank 62 by a hydraulic pump 61 to forcibly feed the working fluid to the head side chamber 10B of the board hold-down cylinder 10 via a check valve 64 and a directional selector valve 65.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a counter hydraulic die set provided in a hydraulic press.

[0002]

2. Description of the Related Art Conventionally, a counter hydraulic die set for performing counter hydraulic forming is provided in a press machine dedicated to counter hydraulic forming. Can not do. Further, after the back pressure on the molding material and the plate pressing force for pressing the edge of the molding material are set stepwise in correspondence with the plurality of molding stroke positions, the setting is started when the molding is started. The hydraulic pressure unit and the plate pressing unit are controlled stepwise so that the actual back pressure and plate pressing force match the set values for each stroke.

[0003]

The conventional counter hydraulic die set described above is provided in a press for exclusive use of counter hydraulic forming, and cannot perform normal forming such as die cushion forming. When molding, another general-purpose press must be used. Further, the back pressure and the plate pressing force on the molding material are set stepwise in accordance with a plurality of molding stroke positions so that the actual back pressure and the plate pressing force coincide with the set values for each set stroke. In addition, since the hydraulic part and the plate holder are controlled stepwise, the operation of setting the back pressure and the plate holder force is troublesome, and wrinkles and breakage of the molded product are likely to occur. is there.
Therefore, in the present invention, it is a main object of the present invention to make it possible to perform both opposing hydraulic forming and normal forming with a general-purpose press machine by configuring the counter hydraulic die set so as to be detachable from a general-purpose press machine. In addition, it is a subordinate task to continuously control the back pressure and the plate pressing force corresponding to the molding stroke to prevent wrinkles and breakage of the molded product.

[0004]

According to a first aspect of the present invention, there is provided a counter hydraulic die set including a hydraulic portion for generating a back pressure on a molding material and a holding portion for generating a force for holding the molding material. It is to be configured to be detachable from a general-purpose press machine.

According to a second aspect of the present invention, in the counter hydraulic die set of the first aspect, the hydraulic portion has a lower plate in which a hydraulic chamber for generating a back pressure against a molding material is formed.
The holding portion has an upper plate to which a cylinder for generating a force for holding the molding material is attached. The lower plate is detachably attached to a bolster of a general-purpose press machine, and the upper plate is attached to the upper plate. Is configured to be detachably attached to a slide of a general-purpose press.

According to a third aspect of the present invention, there is provided the counter hydraulic die set according to the first or second aspect, further comprising control means for continuously controlling the back pressure and the pressing force corresponding to a molding stroke. is there.

According to the first and second aspects of the present invention, it is possible to perform both the opposing hydraulic forming and the normal forming with a general-purpose press.

According to the third aspect of the present invention, the back pressure generated by the hydraulic portion and the plate pressing force generated by the plate pressing portion can be continuously controlled corresponding to the forming stroke, so that the molded product can be formed. The generation of wrinkles and the occurrence of breakage can be suppressed.

[0009]

Next, an embodiment of the present invention will be described. FIG. 1 is a front view showing a state in which a counter hydraulic die set 2 according to the present invention is mounted on a general-purpose press machine 1. As shown in FIG. 1, the counter hydraulic die set 2
Is mounted between a bolster 5 and a slide 4 driven up and down by a press cylinder 3 driven by hydraulic pressure. The piston rod 3A of the press cylinder 3 is driven to move down and up by hydraulic pressure switching control of the direction switching valve 6, and the slide 4 is attached to the tip of the piston rod 3A. A motor-driven hydraulic pump 7 for supplying pressure oil for driving the piston rod 3A of the press cylinder 3 up and down through a direction switching valve 6 is provided. The hydraulic pump 7 is connected to a suction filter 8 via a suction filter 8. Hydraulic oil is sucked from the tank 9.

The counter hydraulic die set 2 has an upper plate 11 having a plate holding cylinder 10 mounted thereon, and a lower plate 13 having a hydraulic chamber 12 provided therein. The lower plate 13 is fixed to the upper surface of the bolster 5 by bolts. A punch base 14 and a piston rod 10A of a plate holding cylinder 10 are attached to an upper plate 11 fixed to the lower surface of the slide 4, and the plate holding cylinder 10 is fixed to a plate holding frame 15. ing.
Since the punch base 14 is slidably fitted to the plate holding frame 15, the mutual positional accuracy between the punch base 14 and the plate holding frame 15 can be maintained.

The guide post 16 is attached to the plate holding frame 15.
Since the guide post 16 is slidably fitted to the lower plate 13, the mutual positioning accuracy of the plate holding frame 15 and the lower plate 13 can be maintained. The hydraulic chamber 1 provided inside the lower plate 13
A machining fluid receiver 17 for receiving the machining fluid overflowed from the hydraulic chamber 12 is provided on the outer peripheral portion of the workpiece 2.

The die 18, the punch 19, and the plate retainer 20 are dies which are attached in accordance with the shape of a molded product during molding. A die 18 is mounted on the upper surface of the lower plate 13, and a punch 19 is mounted on a lower surface of the punch base 14. A plate holding plate 21 is attached to the lower surface of the plate holding frame 15, and a plate holding plate 20 is attached below the plate. The plate-shaped molding material 22 is sandwiched between the plate holder 20 and the die 18, and is optimally molded by the pressure from above the punch 19 and the back pressure from the hydraulic chamber 12.

The counter hydraulic die set 2 includes a hydraulic pressure control unit 31 for supplying the processing fluid to the hydraulic chamber 12 and controlling the back pressure, and a hydraulic oil supply unit for supplying the plate holding cylinder 10 with hydraulic oil. Plate holding force control unit 3 for controlling holding force
2 are provided. A slide position sensor 33 for detecting the position of the slide 4 and outputting a signal corresponding to the position is attached to the frame 1A of the press 1.

FIG. 2 is a system diagram showing the configuration of the hydraulic pressure control unit 31 and the plate pressing force control unit 32 provided in the press 1. As shown in FIG. 2, the hydraulic pressure control unit 31 sucks the processing liquid from the processing liquid tank 42 via the filter 43 by the processing liquid supply pump 41, and supplies the processing liquid via the switching valve 44 and the check valve 50. The hydraulic chamber 12
It is configured to supply to. When the hydraulic chamber 12 is filled with the working fluid, the switching valve 44 is closed based on a fill detection signal from a fill detector (not shown) or the like.
Further, a pressure sensor 45 for detecting the pressure of the working fluid, that is, the back pressure of the hydraulic chamber 12 is provided. When the hydraulic pressure in the hydraulic pressure chamber 12 reaches the upper limit pressure, the switching valve 44 is closed and another switching valve 46 is opened, and the processing fluid discharged from the processing fluid supply pump 41 passes through the filter 47 to the processing fluid tank 42.
Is returned to. The upper limit of the supply pressure of the working fluid is controlled by the pressure control valve 48.

The pressure control servo valve 49 is connected to the punch 19
Controls the pressure of the working fluid when the working fluid in the hydraulic chamber 12 is pushed through the molding material 22. That is, when the working fluid in the hydraulic chamber 12 is compressed and the working fluid is discharged from the hydraulic chamber 12, the working fluid whose backflow is stopped by the check valve 50 is transferred to the working fluid tank 42 via the filter 51. By controlling the return flow rate, the pressure of the working fluid in the hydraulic chamber 12 is controlled. The hydraulic pressure control unit 31 is provided with a hydraulic servo control unit 55 and a hydraulic pressure command unit 56. The configurations of the hydraulic servo control unit 55 and the hydraulic command unit 56 will be described later.

Next, the plate pressing force control unit 32 will be described. The plate pressing force control unit 32 supplies hydraulic oil to the plate pressing cylinder 10 and controls the plate pressing force against the molding material 22. When the slide 4 is at the rising end, a hydraulic oil tank 62 is operated by the hydraulic pump 61. , A hydraulic oil is sucked through a filter 63, and the hydraulic oil is pressure-fed to a head side chamber 10B of the plate holding cylinder 10 through a check valve 64 and a direction switching valve 65.

The head side chamber 10B of the plate holding cylinder 10
When hydraulic oil is supplied to the plate, the plate holding cylinder 10 moves down without moving the piston rod 10A attached to the upper plate 11, and the plate holding frame 15 integrated with the cylinder 10 moves down. Move to the end. The upper limit of the supply pressure of the hydraulic oil is controlled by the pressure control valve 66.

When the slide 4 is lowered in the above state, the plate holder 20 comes into contact with the molding material 22 on the die 18, and when the slide 4 is further lowered, the plate holder cylinder 1
Hydraulic oil in the 0 head side chamber 10B is compressed. The pressure control servo valve 67 controls the flow rate of the hydraulic oil whose backflow has been stopped by the check valve 64 to the hydraulic oil tank 62 via the filter 68, thereby operating the head side chamber 10B of the plate holding cylinder 10. The oil pressure is controlled. A pressure sensor 70 is provided for detecting the pressure of the hydraulic oil in the head side chamber 10B of the plate holding cylinder 10. In addition, a flow control valve 69 for adjusting the pressure of the hydraulic oil in the rod side chamber 10 </ b> C of the plate holding cylinder 10 and adjusting the rising speed of the plate holding cylinder 10 is provided. The plate pressing force control unit 32 includes a hydraulic servo control unit 71 and a hydraulic command unit 7.
2 are provided. The configurations of the hydraulic servo control unit 71 and the hydraulic command unit 72 will be described later.

Next, the configuration of the hydraulic servo control unit 55 and the hydraulic command unit 56 and the configuration of the hydraulic servo control unit 71 and the hydraulic command unit 72 will be described. As shown in FIG. 3, the hydraulic servo control unit 55 controls the pressure control servo valve 49 so that the back pressure generated in the hydraulic chamber 12 matches the command value from the hydraulic pressure command unit 56. Control. Therefore, the hydraulic servo control unit 55 compares the command value corresponding signal from the hydraulic pressure command unit 56 with the hydraulic pressure detection signal from the pressure sensor 45 and outputs a deviation signal to a comparator 55A. And an amplifier 55B for amplifying the deviation signal output from the comparator 55A. Then, a drive current is supplied from the amplifier 55B to the pressure control servo valve 49.

Next, the hydraulic servo control unit 71 controls the pressure control servo valve 67 so that the oil pressure in the plate holding cylinder 10 matches the command value from the oil pressure command unit 72. For this reason, the hydraulic servo control unit 71 determines whether the signal corresponding to the command value from the hydraulic pressure
A comparator 71A that outputs a deviation signal by comparing and calculating a hydraulic pressure detection signal from the controller 71A and an amplifier 71B that amplifies the deviation signal output from the comparator 71A are provided. Then, a drive current is supplied from the amplifier 71B to the pressure control servo valve 67.

The hydraulic command section 56 and the hydraulic command section 72 are constituted by a computer 74. The slide position detection signal output from the slide position sensor 33 and amplified by the amplifier 73 is input to the hydraulic pressure command section 56 and the hydraulic pressure command section 72. The slide position sensor 33 detects the position from the upper surface of the bolster 5 to the lower surface of the slide 4, and the hydraulic pressure command unit 56 and the hydraulic command unit 72 send the next molding stroke S based on the slide position detection signal. The calculation is performed using equation (1). S = H1 + H2 + H3 + H4 + t-S1 (1) where H1 is the dimension from the lower surface of the lower plate 13 to the die 18 mounting surface H2 is the thickness of the die 18 H3 is the height of the punch 19 H4 is the height of the punch base 14 The dimension t from the lower surface to the upper surface of the upper plate 11 is the thickness of the molding material 22, and S1 is the slide position based on the slide position detection signal. FIG. 4 illustrates the above dimensions,
Since H4 and t are known, the slide position sensor 33
If the detected S1 is known, the molding stroke S can be calculated.

Back pressure data corresponding to the molding stroke S is input to the hydraulic pressure command section 56 in advance, and the molding pressure is calculated based on the slide position S1 detected by the slide position sensor 33. The back pressure data corresponding to the pressure S is output to the hydraulic servo control unit 55.

Also, hydraulic pressure data corresponding to the molding stroke S is input to the hydraulic pressure command unit 72 in advance, and the molding stroke is calculated based on the slide position S1 detected by the slide position sensor 33. The hydraulic pressure data corresponding to the pressure S is output to the hydraulic servo control unit 71.

Next, the operation of the counter hydraulic die set 2 attached to the press 1 will be described. When the slide 4 is at the rising end, the hydraulic pressure control unit 31 sucks the processing liquid from the processing liquid tank 42 via the filter 43 by the processing liquid supply pump 41, and switches the processing liquid to the switching valve 44 and the check valve 50. To the hydraulic chamber 12 When the hydraulic chamber 12 is filled with the working fluid, the switching valve 44 is closed and the switching valve 46 is opened based on a filling detection signal from a filling detector or the like (not shown). The discharged working fluid is returned to the working fluid tank 42 via the filter 47.

When the slide 4 is at the rising end, the plate pressing force control unit 32 sucks the hydraulic oil from the hydraulic oil tank 62 through the filter 63 by the hydraulic pump 61 and switches the hydraulic oil to the check valve 64 in the direction. The pressure is fed to the head side chamber 10B of the plate holding cylinder 10 through the valve 65. When hydraulic oil is supplied to the head side chamber 10B of the plate holding cylinder 10, the piston rod 10A attached to the upper plate 11 does not move and the plate holding cylinder 10 descends.
The plate holding frame 15 integrated with the cylinder 10 moves to the lower end.

When the slide 4 is lowered from the rising end based on the lowering command in the above state, the plate holder 20 is moved to the die 18.
It contacts the overlying molding material 22. When the slide 4 further moves down, the hydraulic oil in the head side chamber 10B of the plate holding cylinder 10 is compressed, so that the pressure control servo valve 67 returns the hydraulic oil to the hydraulic oil tank 62 via the filter 68 to form the molding material 22. To control the plate holding force. In the plate pressing force control, the hydraulic command unit 72 sends the hydraulic data corresponding to the forming stroke S calculated based on the slide position S1 detected by the slide position sensor 33 to the hydraulic servo control unit 71. For output, the hydraulic servo control unit 71 supplies a drive current to the pressure control servo valve 67 based on the deviation between the hydraulic data and the hydraulic pressure detected by the pressure sensor 70, and the plate holder 20 moves the die 18. Molding material 2 above
2 is continuously controlled.

When the slide 4 further descends, the punch 19
Starts to push the working fluid filled into the hydraulic chamber 12 via the molding material 22. In this state, the processing liquid in the hydraulic chamber 12 is compressed because it is closed by the molding material 22 pressed between the plate holder 20 and the die 18. The pressure control servo valve 49 controls the back pressure generated in the hydraulic chamber 12 by returning the compressed working fluid to the working fluid tank 42 via the filter 51. In the above-mentioned back pressure control, the hydraulic pressure command unit 56 sends back pressure data corresponding to the molding stroke S calculated based on the slide position S1 detected by the slide position sensor 33 to a hydraulic servo control unit. To output to 55
The hydraulic servo control unit 55 includes the back pressure data and the pressure sensor 4
A drive current based on the deviation from the detected hydraulic pressure is applied to the pressure control servo valve 49 to continuously control the back pressure generated in the hydraulic chamber 12.

When the slide 4 is lowered to the set lower limit position, the molding is completed and the molding material 22 becomes a molded product. Therefore, the slide 4 starts to rise based on the rising command and returns to the rising end. When the press cycle is completed.

The molding height is determined by determining the lower limit position of the slide 4. In order to determine the slide lower limit position, for example, a slide lower limit position regulating block 11A as shown in FIG. 2 is used. The molding height SO is calculated by the following equation (2). SO = H3 + H4- (H5 + H6 + B + H7) (2) Here, as shown in FIG. 4, H3 is the height of the punch 19, H4 is the dimension from the lower surface of the punch base 14 to the upper surface of the upper plate 11, and H5 is the plate. The total dimension of the thickness of the holding plate 21 and the thickness of the plate holder 20 is H6, the dimension from the lower surface to the upper surface of the plate holding frame 15, H7 is the thickness of the upper plate 11, B is the thickness of the slide lower limit position regulating block 11A. In the above equation, since H3 to H7 and SO are known, the B dimension can be calculated from equation (2).

There are two limitations on the draw forming of a thin plate: "limit due to generation of wrinkles" and "limit due to occurrence of breakage". “Wrinkles” are classified into “flange wrinkles” and “body wrinkles” according to the location of occurrence. “Flange wrinkles” are caused by an increase in circumferential compressive stress generated in a flange portion of the molding material 22 due to a movement of the outer edge of the plate-like molding material 22 toward the center with the progress of drawing. It is known that buckling is the cause, and the minimum pressing pressure for suppressing the buckling is a function of the forming stroke according to the theory of buckling of a thin plate. The minimum pressing force Hf for suppressing “flange wrinkles” can be expressed by the following equation. Hf = F1 (S) where S is the forming stroke and F1 (S) is a function of the forming stroke.

"Body wrinkling" is caused by buckling of a thin plate due to an increase in circumferential compressive stress generated in an overhang portion on the side surface of a truncated cone during drawing of a truncated cone. .
In order to suppress the generation of wrinkles, there are a method of pulling in the radial direction and a method of generating pressure in the thickness direction. In the ordinary drawing method, a method of increasing the sheet pressing force and pulling in the radial direction is adopted, whereas in the opposed hydraulic method using the counter hydraulic die set of the present invention, the sheet pressing force is increased and the sheet is pulled in the radial direction. Since the method and the method of increasing the back pressure of the hydraulic chamber and applying pressure in the plate thickness direction can be used in combination, it is possible to perform more appropriate molding than the ordinary molding method. The minimum back pressure pcr for suppressing "body wrinkles" can be expressed by the following equation. pcr = F2 (S)

The "limit due to the occurrence of breakage" determines the maximum value of the plate pressing force and the back pressure. When the plate holding force is excessive, breakage generally occurs at the punch shoulder R portion. This is because a radial tensile stress is generated with the progress of molding, and the radial tensile stress exceeds the allowable tensile stress of the thin plate (molding material 22). In addition, when the back pressure is excessive, breakage generally occurs at the overhang portion near the die shoulder R portion. This is presumed to be because the back pressure of the hydraulic chamber 12 acts on the overhang portion of the molded product and swells this portion.

The maximum allowable back pressure pal is estimated by the following equation. pal = σal × 4 × t / (D−d) where σal is the allowable tensile stress of the thin plate t is the thickness of the thin plate D is the inner diameter of the die d is the contact point diameter of the punch and the thin plate The contact point diameter of the punch 19 and the thin plate Is determined by the shape of the punch and the molding stroke, so the maximum allowable back pressure pal is also a function of the molding stroke.

As described above, the plate pressing force and the back pressure have an allowable range determined by the molding stroke. Fig. 5 shows the "flange wrinkle" determined by the pressing force and the forming stroke.
FIG. 6 shows the occurrence limit and break limit of "body wrinkle" determined by the back pressure and the forming stroke.

As described above, the counter hydraulic die set 2
According to the method, the pressing force and the back pressure are continuously controlled in accordance with the molding stroke determined by the molding shape of the molding material 22, so that the molding limit can be improved and the molding can be performed to the optimum molding shape.

FIG. 7 shows a state in which the counter hydraulic die set 2 attached to the general-purpose press 1 has been replaced with a normal die set. After removing the counter hydraulic die set 2 from the general-purpose press 1, a die set 81 is attached as shown in FIG. 7. The upper plate 82 of the die set 81 is fixed to the slide 4 by bolts. You. A die 83 is fixed to the upper plate 82, and a die 84 is attached to the lower surface of the die 83. A punch 87 is attached to a lower plate 86 fixed to the bolster 85 by bolts. The plate holder 88 is placed on the die cushion pin 89,
The lower end of the die cushion pin 89 (one in the drawing, but there are actually a plurality) is in contact with the die cushion pad 90. In the die set 81 having the above-described structure, the molding material sandwiched between the die 84 and the plate holder 88 by the stroke of the slide 4 by the hydraulic cylinder and the hydraulic drive of the hydraulic cylinder provided below the die cushion pad 90. Molded.

As described above, since the counter hydraulic die set 2 and the die set 81 can be exchangeably attached to the general-purpose press machine 1, molding is performed by the counter hydraulic forming method using the counter hydraulic die set 2. It is possible to correspond to a molded product that is desirably used and a molded product that is desirably subjected to normal molding using the die set 81 and the like.

[0038]

According to the first and second aspects of the present invention,
With a general-purpose press machine, it is possible to perform both the opposing hydraulic forming and the normal forming.

According to the third aspect of the present invention, since the back pressure generated by the hydraulic section and the sheet pressing force generated by the sheet pressing section can be continuously controlled in accordance with the forming stroke, the molded article can be formed. The generation of wrinkles and the occurrence of breakage can be suppressed.

[Brief description of the drawings]

FIG. 1 is a front view showing a state in which a counter hydraulic die set is attached to a general-purpose press.

FIG. 2 is a control block diagram for controlling a back pressure and a plate pressing force of a counter hydraulic die set.

FIG. 3 is an electrical control block diagram of a counter hydraulic die set.

FIG. 4 is a dimensional view of a molding stroke and the like of a counter hydraulic die set.

FIG. 5 is a characteristic diagram of occurrence of flange wrinkles.

FIG. 6 is a graph showing the occurrence characteristics of body wrinkles.

FIG. 7 is a front view of a state in which a die set is attached to a general-purpose press.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 General-purpose press machine 2 Counter hydraulic die set 4 Slide 5 Bolster 10 Plate holding cylinder 10A Piston rod 11 Upper plate 12 Hydraulic chamber 13 Lower plate 14 Punch base 15 Plate holding frame 16 Guide post 18 Dice 19 Punch 20 Plate holder 21 Plate holder plate 22 Molding material 31 Hydraulic pressure control unit 32 Plate pressure control unit 33 Slide position sensor 45 Pressure sensor 55 Hydraulic servo control unit 56 Hydraulic pressure command unit 70 Pressure sensor 71 Hydraulic servo control unit 72 Hydraulic command unit 81 Die set

Claims (3)

[Claims] 1. A counter hydraulic die set including a hydraulic part for generating a back pressure on a molding material and a holding part for generating a force for holding the molding material, the counter hydraulic die set being detachable from a general-purpose press. A counter hydraulic pressure die set comprising: 2. The hydraulic part has a lower plate having a hydraulic chamber for generating a back pressure against the molding material, and the holding part is provided with a cylinder for generating a force for holding the molding material. An upper plate, wherein the lower plate is detachably attached to a bolster of a general-purpose press, and the upper plate is detachably attached to a slide of the general-purpose press. 2. The counter hydraulic die set according to claim 1, wherein: 3. The counter hydraulic die set according to claim 1, further comprising control means for continuously controlling said back pressure and said pressing force in accordance with a molding stroke.