JP5695371B2 - Die cushion device - Google Patents

Description

  The present invention relates to a die cushion device, and more particularly to a die cushion device that can improve the accuracy of cushion pressure and at the same time sufficiently reduce the impact on the die cushion device.

In general, in a press machine that presses a sheet, a die cushion device is provided so that the sheet does not wrinkle during pressing.
The die cushion device applies pressure (hereinafter referred to as “cushion pressure”) that biases upward against the processing pressure downward during pressing to the peripheral edge of the seat.

In such a die cushion device, a hydraulic chamber is provided to mitigate the impact on the die cushion device and to measure the pressure at the time of the impact.
For example, a cylinder is formed at the lower part of the cushion pad, a piston connected to the upper end of the rod inside the cylinder is slidably accommodated, and a die cushion having a hydraulic chamber formed by the inner wall surface of the cylinder and the wall surface of the piston An apparatus is known (see, for example, Patent Document 1).
Also, a cushion pad, a support attached to the lower surface of the cushion pad, a fluid pressure cylinder provided on the support and biasing the cushion pad upward, and attached to the support and biasing the cushion pad upward There is known a die cushion device including an upper urging device, a drive source for driving the upper urging device, and a hydraulic chamber provided between the cushion pad and the column (for example, Patent Document 2). reference).

JP 2006-15407 A JP 2009-142894 A

However, in the die cushion device described in Patent Documents 1 and 2, the responsiveness of the press machine cannot be adjusted, so that sufficient cushion pressure accuracy cannot be obtained. For this reason, in these die cushion apparatuses, when the natural frequency of a press machine and a die cushion apparatus changes, for example, there exists a fault that the moldability of a sheet worsens.
In addition, a method of improving the responsiveness of the press machine by adjusting the pressure in the hydraulic chamber can be considered, but the natural frequency changes variously depending on the specifications such as the structure and capacity of the press machine and the die cushion device, the processing speed, etc. There is a limit to just adjusting the pressure in the hydraulic chamber.
In general, by providing a hydraulic chamber, the impact on the die cushion device is reduced, but the cushion pressure responsiveness of the die cushion device tends to decrease.

  The present invention has been made in view of the above circumstances, and by adjusting the responsiveness of the press machine, the accuracy of the cushion pressure of the die cushion device is improved, and at the same time, the impact on the die cushion device is sufficiently mitigated. An object of the present invention is to provide a die cushion device that can be used.

  The present inventor has intensively studied to solve the above-mentioned problems, and has found that the above-mentioned problems can be solved by making the volume of the hydraulic chamber variable, and has completed the present invention.

The present invention is (1) a die cushion device that exerts a cushion pressure against a downward processing pressure during pressing, wherein the cushion pad, a hydraulic chamber provided in the cushion pad, A piston slidable on the wall; a support rod abutted against the piston; an upper urging device provided on the support rod for urging the cushion pad upward; and for driving the upper urging device comprising a driving source, the volume of the hydraulic chamber has become possible variation, the hydraulic chamber and outer chamber is attached communicating with the hydraulic chamber, by sliding the chamber piston of the external chamber In the die cushion device, the volume of the hydraulic chamber is variable.

The present invention (2) above the hydraulic pump unit of the hydraulic chamber pressure regulating is provided (1) consists in a die cushion apparatus according.

The present invention resides in ( 3 ) the die cushion device according to the above ( 1 ), wherein the hydraulic chamber is provided with an overload prevention valve communicating with the hydraulic chamber.

  The present invention resides in the die cushion device according to any one of (1) to (5), wherein (6) the upper biasing device is an air cylinder and a rack and pinion mechanism, and the drive source is a servo motor.

In the die cushion device of the present invention, by adjusting the natural frequency of the press machine and the die cushion device during pressing by changing the volume of the hydraulic chamber, the cushion pressure response of the die cushion device is excellent. At the same time, the impact on the die cushion device can be sufficiently mitigated.
In addition, the natural frequency generally varies depending on the structure and size of the press machine and the die cushion device, the property of the oil in the hydraulic chamber, etc., but the die cushion device allows the volume of the hydraulic chamber to vary, As appropriate, the natural frequency can be adjusted to a specific value. That is, the natural frequency may change not only when the structure of the press machine and the die cushion device changes, but also when the oil cleanliness of the hydraulic chamber and the degree of air penetration change over time. However, in the above-described die cushion device, the natural frequency can be adjusted by changing the volume of the hydraulic chamber even after the design stage (after mechanical assembly), so that the natural frequency becomes a specific value as appropriate. Can be adjusted as follows.

In the die cushion device of the present invention, the piston is provided with an attachment portion for attaching the fluid amount adjusting block to the piston. By attaching the fluid amount adjusting block to the attachment portion, the volume of the hydraulic chamber can be easily adjusted. It can be carried out.
In addition, an external chamber communicating with the hydraulic chamber is attached to the hydraulic chamber, and the volume of the hydraulic chamber can be easily adjusted by sliding a piston for the chamber of the external chamber.

  In the die cushion device of the present invention, when a hydraulic pump unit for regulating pressure is provided in the hydraulic chamber, the hydraulic pressure in the hydraulic chamber can be adjusted. As a result, the natural frequency can be finely adjusted.

  In the die cushion device of the present invention, when an overload prevention valve communicating with the hydraulic chamber is provided in the hydraulic chamber, the overfilling of the fluid filled in the hydraulic chamber is prevented when an overload based on the processing pressure occurs. By letting it flow out of the valve, for example, the failure of the press machine can be suppressed by stopping the drive of the press machine. Further, when the overload based on the processing pressure converges, the liquid is easily returned to the hydraulic chamber by flowing the liquid from the overload prevention valve into the hydraulic chamber, so that it becomes easy to drive the press machine again. .

  In the die cushion device of the present invention, when the upper urging device is an air cylinder and a rack and pinion mechanism, and the drive source is a servo motor, it is possible to achieve optimum mechanical characteristics under any specifications and conditions. . That is, in the servo die cushion device using a servo motor, the control frequency and formability are improved by adjusting the natural frequency of the press machine and servo die cushion device during pressing, and the corresponding molding conditions can be expanded. It becomes possible to plan.

FIG. 1 is a schematic cross-sectional view showing a die cushion device according to a first embodiment. FIG. 2 is a partially enlarged view showing a hydraulic chamber of the die cushion device according to the first embodiment. FIG. 3 is a partially enlarged view showing a hydraulic chamber of the die cushion device according to the second embodiment.

  Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the drawings as necessary. In the drawings, the same elements are denoted by the same reference numerals, and redundant description is omitted. Further, the positional relationship such as up, down, left and right is based on the positional relationship shown in the drawings unless otherwise specified. Further, the dimensional ratios in the drawings are not limited to the illustrated ratios.

  The die cushion device according to the present invention is a device for biasing the cushion pressure toward the periphery of the seat against the processing pressure downward when the seat is pressed. In the present invention, “working pressure” means a downward pressure transmitted to a sheet when the sheet is pressed by a press machine. Such processing pressure is appropriately determined depending on the shape of the sheet and the speed of pressing. The “cushion pressure” means a pressure that biases the seat upward in accordance with the processing pressure.

  Further, in the present invention, the “natural frequency” means a specific vibration detected by the vibration during pressing, and specifically means a specific frequency by the press machine and the die cushion device.

[First Embodiment]
First, a first embodiment of the die cushion device of the present invention will be described.
FIG. 1 is a schematic cross-sectional view showing a die cushion device according to a first embodiment.
As shown in FIG. 1, the die cushion device 100 according to the first embodiment includes a cushion pad 11, a hydraulic chamber 16 provided in the cushion pad 11, and a piston 15 b that can slide on the wall surface of the hydraulic chamber 16. A support rod 12 in contact with the piston 15b, an air cylinder 13 that is an upper biasing device provided on the middle of the support rod 12 and biases the cushion pad 11 upward, and a lower portion of the support rod 12 And a rack and pinion mechanism 14 that is an upper biasing device that biases the cushion pad 11 upward, and a servo motor 17 that is a drive source for driving the rack and pinion mechanism 14.
The hydraulic chamber 16 is provided with an overload prevention valve 20 communicating with the hydraulic chamber 16 and a pressure adjusting hydraulic pump unit 21.

In the die cushion device 100, the volume of a hydraulic chamber 16, which will be described later, can be changed, and thereby the natural frequency during pressing can be adjusted.
The natural frequency during pressing is preferably 3 to 9 Hz, for example. In this case, the cushioning pressure response of the die cushion device is excellent, and at the same time, the impact on the die cushion device can be sufficiently reduced.
Further, the natural frequency varies depending on the structure and size of the press machine and the die cushion device, the property of the oil in the hydraulic chamber, etc., but the die cushion device 100 allows the volume of the hydraulic chamber 16 to be varied. The natural frequency can be adjusted as appropriate within the above range.

FIG. 2 is a partially enlarged view showing a hydraulic chamber of the die cushion device according to the first embodiment.
As shown in FIG. 2, in the die cushion device 100 according to the first embodiment, the hydraulic chamber 16 provided in the cushion pad 11, a cap 15 a that seals the upper surface of the hydraulic chamber 16, and the wall surface of the hydraulic chamber 16 And a piston 15b that slides. The hydraulic chamber 16 is filled with oil.

Here, the piston 15b is provided with an attaching portion 22a for attaching the liquid amount adjusting block 22 at the upper end of the piston 15b. By attaching the liquid amount adjusting block 22 to the attaching portion 22a, the hydraulic chamber 16 The volume changes. When attaching the liquid amount adjusting block 22, the cap 15a is removed, and the liquid amount adjusting block 22 is inserted into the attaching portion 22a from above.
Further, the volume of the hydraulic chamber 16 can be gradually reduced by increasing the number of the liquid amount adjusting blocks 22 attached to the attachment portion 22a.

  The liquid amount adjusting block 22 is fixed to the mounting portion 22a of the piston 15b with a pin P. When a plurality of liquid amount adjusting blocks 22 are stacked, each liquid amount adjusting block 22 is penetrated by a pin P and fixed to the piston 15b at the same time.

  As a result, not only the natural frequency can be adjusted based on the characteristics (hardness) of the oil filled in the hydraulic chamber 16, but also the natural frequency can be adjusted based on the change in the volume of the hydraulic chamber 16 itself. For example, when the liquid amount adjusting block 22 is attached, the liquid amount in the hydraulic chamber 16 is smaller (the volume in the hydraulic chamber 16 is smaller) than when the liquid amount adjusting block 22 is not attached. As a result, the natural frequency increases. Therefore, when it is desired to increase the natural frequency, it is sufficient to increase the number of attached liquid quantity adjusting blocks 22.

Returning to FIG. 1, the die cushion device 100 includes an air cylinder 13 and a rack and pinion mechanism 14 as an upward biasing device. For this reason, when a downward processing pressure is generated during pressing, the cushion pressure by these upper biasing devices opposes the processing pressure.
At this time, in the die cushion device 100, the cushion pressure required for the rack and pinion mechanism 14 is reduced by the amount of the air cylinder 13, so that the rack and pinion mechanism 14 and the servo motor 17 can be downsized or the rack and pinion mechanism 14 and the like. The service life of the reduction gear 18 can be extended, and maintenance is facilitated.
Moreover, since the air cylinder 13 and the rack and pinion mechanism 14 generate cushion pressure on the same axis, accurate full-closed loop control is possible, and the cushion pressure accuracy of the die cushion device 100 is improved. Will do.

The air cylinder 13 is located in the middle of the support rod 12 and is filled with air and sealed. Thereby, the cushion pad 11 is supported by the air pressure.
An air tank 19 is provided so that air inside the air cylinder 13 can flow in and out. That is, the cushion pressure of the air cylinder 13 is adjusted to be substantially constant by the inflow and outflow of air from the air tank 19.

Here, the cushion pressure by the air cylinder 13 increases as the internal air pressure rises as it is pushed down as the processing proceeds.
As a result, the inertial force accompanying the weight of the upper movable part from the support rod 12 cancels out the increase in the cushioning force due to the increase in air pressure. Therefore, at the final stage of processing, the cushioning force is reduced by the inertial force of the movable part. Can be prevented. Furthermore, the air from the air tank 19 flows into and out of the air cylinder 13 so that the cushion force acting against the weight of the upper movable part from the support rod 12 does not increase excessively. Note that if the weight of the upper movable portion from the support column 12 is borne by the cylinder cushion pressure, the upper biasing device is only subjected to the downward varying processing pressure during pressing.

The rack and pinion mechanism 14 includes a rack cage 14a and a pinion shaft 14b meshed with the rack cage 14a.
The rack cage 14 a is connected to the lower end of the column 12 and moves up and down together with the column 12.
On the other hand, the pinion shaft 14 b is meshed with the rack cage 14 a and is connected to the servo motor 17.
That is, the rack and pinion mechanism 14 is driven by the servo motor 17.

Since the rack and pinion mechanism 14 does not rotate like a ball screw, the rotation inertia force is small and the acceleration / deceleration performance is excellent, so that an accurate cushioning force can be instantly exhibited.
In addition, since the die cushion device 100 includes the air cylinder 13, the processing pressure applied to the meshing position between the rack rod 14a and the pinion shaft 14b of the rack and pinion mechanism 14 is reduced. For this reason, wear between the teeth is reduced, the backlash of the rack and pinion mechanism 14 hardly occurs, and the life of the rack and pinion mechanism 14 is extended.

  In the die cushion device 100 according to the present embodiment, the upper urging device is the air cylinder 13 and the rack and pinion mechanism 14, and the drive source is the servo motor 17, so that optimum mechanical characteristics are realized under any specifications and conditions. It becomes possible to do. That is, in the servo die cushion device using the servo motor 17, by controlling the natural frequency at the time of pressing, the control accuracy and formability are improved, and the corresponding molding conditions can be expanded.

  In the die cushion device 100, a hydraulic pump unit 21 for pressure adjustment is provided in the hydraulic chamber 16. For this reason, the hydraulic pressure of the hydraulic chamber 16 can be adjusted. Thereby, in addition to the adjustment of the natural frequency of the die cushion device by the volume of the hydraulic chamber 16 described above, the natural frequency of the die cushion device by the hydraulic pump unit 21 can be finely adjusted.

  In the die cushion device 100, an overload prevention valve 20 communicating with the hydraulic chamber 16 is provided in the hydraulic chamber 16. For this reason, when an overload based on the processing pressure occurs, the liquid filled in the hydraulic chamber is caused to flow out of the overload prevention valve, for example, to suppress the press machine failure by stopping the press machine drive. be able to. Further, when the overload based on the processing pressure converges, the liquid is easily returned to the hydraulic chamber by flowing the liquid from the overload prevention valve into the hydraulic chamber, so that it becomes easy to drive the press machine again. .

In the die cushion device 100 according to the present embodiment, first, a workpiece (not shown) is pressed.
When the processing pressure at that time is transmitted to the die cushion device 100, the cushion pad 11 and the support rod 12 which are movable parts of the die cushion device 100 move downward.

  Here, since the hydraulic chamber 16 is provided between the cushion pad 11 and the support rod 12, the processing pressure is transmitted from the cushion pad 11 to the hydraulic chamber 16. At this time, in the die cushion device 100, since the natural frequency of the die cushion device is adjusted by changing the volume of the hydraulic chamber 16, the support rod 12, the air cylinder 13, the rack pinion below the hydraulic chamber 16 are adjusted. The impact due to the processing pressure on the mechanism 14 and the servo motor 17 can be sufficiently mitigated.

  On the other hand, in the die cushion device 100, the cushion pressure generated by the air cylinder 13 and the rack and pinion mechanism 14 is transmitted to the hydraulic chamber 16. At this time, in the die cushion device 100, since the natural frequency is adjusted by changing the volume of the hydraulic chamber 16, the accuracy of the cushion pressure is more reliably improved by the accurate full-closed loop control described above. Can do.

  Therefore, in the die cushion device 100, even if the press on the workpiece is continuously repeated, the accuracy of the cushion pressure of the die cushion device is excellent and the impact on the die cushion device can be sufficiently reduced. .

[Second Embodiment]
Next, a second embodiment of the die cushion device of the present invention will be described.
The die cushion device according to the second embodiment is the same as the die cushion device 100 according to the first embodiment except that the structure of the hydraulic chamber is different.

FIG. 3 is a partially enlarged view showing a hydraulic chamber of the die cushion device according to the second embodiment.
As shown in FIG. 3, in the die cushion device according to the second embodiment, the hydraulic chamber 16 provided in the cushion pad 11, the piston 15 b sliding on the wall surface of the hydraulic chamber 16, and the oil in the hydraulic chamber 16 And an external chamber 30 communicated so as to be able to flow in and out. The hydraulic chamber 16 is filled with oil.

The external chamber 30 includes a chamber cylinder 30a, a chamber piston 30b, and a ball screw 30c that is in contact with the chamber piston 30b and screwed into the chamber cylinder 30a.
In the external chamber 30, by rotating the ball screw 30c, the chamber piston 30b can slide on the wall surface of the chamber cylinder 30a. The rotation of the ball screw 30c may be manual or electric.

  The external hydraulic chamber 36 formed by the chamber cylinder 30 a and the chamber piston 30 b of the external chamber 30 is filled with oil and communicated with the hydraulic chamber 16 through the pipe 31. That is, an external chamber 30 communicating with the inside of the hydraulic chamber 16 is attached to the hydraulic chamber 16, and by sliding the chamber piston 30 b of the external chamber 30, the hydraulic chamber 16, the pipe 31, and the external hydraulic chamber are provided. The total volume with 36 can be changed.

  As a result, not only the natural frequency can be adjusted based on the characteristics (hardness) of the oil filled in the hydraulic chamber 16, but also the natural frequency can be adjusted based on the change in the volume of the hydraulic chamber 16 itself. For example, when the external hydraulic chamber 36 of the external chamber 30 is made small, the total amount of liquid in the hydraulic chamber 16, the pipe 31, and the external hydraulic chamber 36 is reduced (in the hydraulic chamber 16, the pipe 31, and the external hydraulic chamber 36). Therefore, the natural frequency of the die cushion device 100 increases. Therefore, in order to increase the natural frequency of the die cushion device 100, the volume of the external hydraulic chamber 36 of the external chamber 30 may be reduced.

  The preferred embodiment of the present invention has been described above, but the present invention is not limited to the above embodiment.

  For example, in the die cushion device 100 according to the present embodiment, two types of air cylinder 13 and rack and pinion mechanism 14 are used as the upper urging device, but a ball screw or the like may be used instead of these. The type and number of urging devices are not limited.

  In the die cushion device 100 according to the first embodiment, the shape (size) and material of the liquid amount adjusting block 22 are not particularly limited as long as they can withstand pressure.

  In the die cushion device according to the second embodiment, the chamber piston 30b is moved by the ball screw 30c, but is not limited to the ball screw 30c, and may be a rack and pinion mechanism, an air cylinder, or the like.

  The die cushion device of the present invention is used in a press machine that presses a sheet. By using the die cushion device of the present invention, the cushion pressure response is excellent, and at the same time, the impact on the die cushion device can be sufficiently reduced.

DESCRIPTION OF SYMBOLS 11 ... Cushion pad 12 ... Support rod 13 ... Air cylinder 14 ... Rack and pinion mechanism 14a ... Rack hook 14b ... Pinion shaft 15a ... Cap 15b ... Piston 16 ...・ Hydraulic chamber 17 ... Servo motor 18 ... Reduction gear 19 ... Air tank 20 ... Overload prevention valve 21 ... Hydraulic pump unit 22 ... Liquid amount adjustment block 22a ... Installation Part 30 ... External chamber 30a ... Cylinder for cylinder 30b ... Piston for chamber 30c ... Ball screw 31 ... Pipe 36 ... External hydraulic chamber 100 ... Die cushion device

Claims (3)

A die cushion device that exerts cushion pressure against the downward processing pressure during pressing,
Cushion pad,
A hydraulic chamber provided in the cushion pad;
A piston slidable on the wall of the hydraulic chamber;
A support rod abutted against the piston;
An upper biasing device that is provided on the support rod and biases the cushion pad upward;
A drive source for driving the upper biasing device;
With
The volume of the hydraulic chamber is variable ,
An external chamber that communicates with the hydraulic chamber is attached to the hydraulic chamber,
A die cushion device in which the volume of the hydraulic chamber is variable by sliding a chamber piston of the external chamber.   2. The die cushion device according to claim 1, wherein a hydraulic pump unit for regulating pressure is provided in the hydraulic chamber.   The die cushion device according to claim 1, wherein the hydraulic chamber is provided with an overload prevention valve communicating with the hydraulic chamber.

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