JPH01182000A - Hydraulic chamber load control device - Google Patents

Abstract

PURPOSE:To simply control the press load of a material by a blank holder by providing a cylinder for pressure control in the liquid pressure chamber of the blank holder and connecting the piston rod thereof to a mechanical driving means in press-forming a metal material, etc., by a double action mechanical press. CONSTITUTION:Pitmans 3, 4 are descended with the rotation of a crank shaft 2, a blank holder 9 is descended toward a bolster 16 with the descent by the pitman 4 and the metal material 20 on a pressure pad 17 is fixed by pressing. The material 20 is simultaneously subjected to pressing by descending a punch 6 with the larger descent amt. e1 than that e2 of the blank holder 9 by the descent of the pitman 3. In this case the pressure reduction chamber of the head side of the cylinder 44 for pressure control is communicated with the liquid pressure chamber 12 of the cylinder 10 for preventing overload of the blank holder 9 and the mechanical driving means consisting of a rack 45 and pinion 46 is provided on the piston rod thereof. The press load of the blank holder is controlled without using the control means of a servovalve, etc.

Description

[Detailed description of the invention] [Industrial application field] TECHNICAL FIELD The present invention relates to a hydraulic chamber load control device.

[Prior Art] For example, a general example of a double-acting mechanical press will be explained with reference to FIG. An inner slide 5 equipped with a punch 6 is connected to the lower end of the pitman 3, and a screw shaft 7 is connected to the lower end of the pitman 4.
or connected.

A cylinder 10 for overload prevention is fitted into a blank holder 9 having a presser plate 8 at its lower end, and a piston 1 having a hollow hole ILa in its axial center is fitted into the cylinder 10 for preventing overload.
A hydraulic chamber 12 is formed inside the cylinder 10 between the piston 1 and the piston 1. Further, above the piston 11, a worm wheel 13 having a female thread in the shaft center is disposed, and the female thread of the worm wheel 13 is inserted into the hollow hole 11a of the piston 11 (see FIG. 8). A screw shaft 7 is inserted and screwed together, and a nut 14 is screwed onto the lower end of the screw shaft 7. So, Natsu 1
4 and drives the worm 15 meshed with the worm wheel 13, the screw shaft 7 attempts to move up and down, but since the position of the screw shaft 7 is determined by the position of the crankshaft 2 and does not move up or down, The blank holder 9 is raised and lowered so that die-hide adjustment can be performed.

In Figure 7, 16 is a bolster, 17 is a pressure pad,
18 is a pressure pin, 19 is a cushion, and 20 is a material.

A blank holder load control device used in the above-mentioned double-acting mechanical press is shown in FIG. 8, in which a cylinder 22 is connected to the other end of a conduit 21 whose one end is connected to the hydraulic pressure chamber 12. Hollow part 2 of cylinder 22 communicating with the hydraulic pressure chamber 12
A small-diameter piston 24 that is movable up and down is fitted in the cylinder 25, and a large-diameter piston 26 that is fit in a cylinder 25 that can be moved up and down is fixed to the lower end of the small-diameter piston 24.
The lower hollow portion 27 of the large-diameter piston 26 can be filled with compressed air supplied via a conduit 28.

At the upper end of the cylinder 22, a pipe line 2 communicating with the hollow part 23 is provided.
9 is connected, and from the pipe line 29 to the hollow part 23 and the pipe line 21
Pressure fluid can be supplied to the hydraulic pressure chamber 12 of the blank holder 9 through the blank holder 7.

In FIG. 8, 30 is a hydraulic pump, 31 is a check valve, 82 is a safety valve, and 33 is a drain hole provided in the middle of the cylinder 22 to return the pressure liquid to the tank 85 via the pipe 34.

When press working is performed using the double-acting mechanical press shown in FIG. 7, the crankshaft 2 is rotated by a drive device (not shown). Then, Pitman 8,4 is the 7th
The lowering starts from the upper limit position shown in the figure, and therefore the inner slide 5 and the blank holder 9 also start lowering. However, since the distance e1 from the rotation center of the crankshaft 2 (the center of the bearing 1) to the pitman 8 pivot joint is larger than the distance e2 from the rotation center of the crankshaft 2 to the pitman 4 joint, Due to the rotation, the inner slide 5 descends faster than the blank holder 9, and the punch 6 attached to the lower end of the inner slide 5 gradually enters the hollow part at the center of the blank holder 9 while descending.

On the other hand, when the blank holder 9 descends by a predetermined amount, the peripheral edge of the material 20 on the bolster lfi is pressed down by the press plate 8, and immediately after that, the punch 6 comes into contact with the material 20, and the blank holder 9 does not descend after that. , the punch 6 descends, and the pressure pad 17 is pushed down by the punch 6, whereby the material 20 is sandwiched between the punch 6 and the pressure pad 17 and press-formed into a predetermined shape.

When the crankshaft 2 further rotates while the presser plate 8 of the blank holder 9 presses the peripheral edge of the material 20, a vertical force acting upward on the pitman 4 is generated via the liquid in the hydraulic chamber 12 and the piston 11. , increases rapidly. Then,
The pressure in the hydraulic chamber 12 increases, and the increased pressure in the hydraulic chamber 12 is transmitted from the pipe line 21 in FIG.

When the pressure in the hydraulic chamber 12 is low and the force acting on the upper surface of the small diameter piston 24 is smaller than the force due to air pressure acting on the lower surface of the large diameter piston 26, the small diameter piston 24 is moved to the upper limit position by the air pressure via the large diameter piston 26. It has been pushed up to. However, when the pressure in the hydraulic chamber 12 increases and the force acting on the upper surface of the small diameter piston 24 becomes greater than the force acting on the lower surface of the large diameter piston 26, the small diameter piston 24 and the large diameter piston 2B are pushed down. When the upper end of the small diameter piston 24 descends to the upper edge of the liquid drain hole 33, the liquid in the hollow portion 28 returns from the liquid drain hole 33 to the tank 35 via the pipe 34. For this reason, the pressure within the hydraulic chamber 12 is held substantially constant, and the presser load on the blank holder 9 is also held substantially constant regardless of the crankshaft rotation angle, as shown by straight line A in FIG. The peripheral edge of the material 20 is held down by a substantially constant load. In this manner, the conventional apparatus prevents the press from being overloaded and also keeps the pressing force of the blank holder substantially constant. Note that there is also a device that uses link motion to keep the presser foot constant.

However, in recent years, it has become necessary to change the presser load of the blank holder 9 according to the crankshaft rotation angle θ, as shown by the straight line and curved line C in FIG. A load control means as shown in Japanese Unexamined Patent Publication No. Sho EiO-281898 has been proposed.

In principle, this load control means can be applied to the pipe line 2 shown in FIG.
A pressure control valve is provided between the cylinder 22 of No. 9 and the check valve 31, an accumulator is provided on the primary side of the pressure control valve, and a control device is further provided to control the operation of the pressure control valve.

Therefore, when a servo valve with good control performance is used as the pressure control valve of the load control means described above, it is necessary to strictly manage the liquid in the entire line in order to maintain the performance of the servo valve.

[Problems to be Solved by the Invention] However, when a servo valve is used in the middle of the pipe line 29, the liquid in the pipe line 29 is easily deteriorated because it is sent to the hydraulic pressure chamber 12 of the blank holder 9 and the tank 35. Therefore, there is a problem in that liquid management is large-scale and difficult.

The present invention has been made in view of the above-mentioned circumstances, and has an object of making it possible to control the load of a blank holder without using a servo valve.

[Means for Solving the Problem] The present invention communicates the hydraulic pressure chamber on the head side of the pressure control cylinder with the hydraulic pressure chamber, and also provides a mechanical drive means for the piston rod of the Yanagawa cylinder on the pressure side = 7- It has a configuration in which the

[Function] According to the pressure change in the hydraulic chamber of the overload prevention cylinder, the volume of the hydraulic chamber of the pressure control cylinder is changed by operating the mechanical drive means and moving the piston of the pressure control cylinder. , thereby controlling the pressure in the hydraulic chamber of the overload prevention cylinder to a predetermined pressure.

[Example] Hereinafter, an example of the present invention will be described with reference to the accompanying drawings.

FIGS. 1 to 3 are explanatory diagrams of an embodiment of the hydraulic chamber load control device of the present invention, which is an example in which the device is applied to a blank holder.

Cylinder 10 for preventing overload of blank holder
A pipe line 36 is connected to the hydraulic pressure chamber 12 formed by the piston 11 and the piston 11.
A hydraulic pump 37 and a check valve 88 are connected to the pipe line 36.
, accumulator 39, check valve 40, relief valve 4
1 is connected, one end of a pipe 42 equipped with a -8= relief valve 43 is connected to the middle part of the pipe 36, and the other end of the pipe 42 is connected to a hydraulic chamber on the head side of a cylinder 44 for pressure control. Connect to.

A mechanical drive means is connected to the cylinder 44.

As the mechanical driving means, a rack 45 is attached to the rod end of the cylinder 44, a pinion 46 is engaged with the rack 45, a lever 48 is attached to the rotating shaft 47 of the pinion 46, and the swinging of the lever 48 causes the pinion to move. 46 so that the piston of the cylinder 44 can be moved.

A rotating body 49 is attached to the crankshaft 2 in FIG. 7, and an elongated hole 50 extending in the radial direction of the crankshaft 2 is provided in the rotating body 49. The screw 53 is installed so that it can be rotated.
A slide 54 is screwed onto the crankshaft 2, and the slide 54 can be moved in the radial direction of the crankshaft 2 by rotation of the screw 53.

A rod 55 connects the tip of the lever 48 fixed to the rotating shaft 47 of the pinion 46 and the slide 54, and when the rod 55 descends due to the rotation of the crankshaft 2, the lever 4
8 swings downward, the piston of the cylinder 44 moves toward the rod, and conversely, due to the rotation of the crankshaft 2, the rod 55
When the lever 48 rises, the lever 48 swings upward and the cylinder 44
so that the piston moves toward the head side.

The structure of the double-acting mechanical press itself is the same as that shown in FIG. 7, and the drive device 52 may be driven by a control device (not shown).

During work, the drive device 52 is operated to move the slide 54 in the radial direction of the crankshaft 2 to set the amount of elevation of the rod 55. When the material 20 is press-formed by the punch 6 shown in FIG. The volume increases, and the pressure applied to the hydraulic chamber 12 of the cylinder 10 of the blank holder decreases. Also, when the rod 55 rises, the piston of the cylinder 44 moves toward the head side, thereby
The volume of the cylinder 44 decreases and the pressure applied to the hydraulic chamber 12 of the cylinder 10 of the blank holder increases. As a result, the presser load of the blank holder 9 in FIG.
According to the setting of the lifting amount, the control can be performed as shown in A, C, C, II, and E of FIG. 9. Note that the setting work for the amount of elevation of the rod 55 should be done in advance before the work.
If the blank holder presser load is to be drastically changed, this may be done during the work.

FIG. 4 is an explanatory diagram of another embodiment of the present invention, in which a slide 57 slidably fitted onto a shaft 56 is cranked by a hydraulic cylinder 58 in a configuration substantially similar to that of FIGS. 1 to 3. It is configured to be movable in the radial direction of the shaft 2.

FIG. 5 is an explanatory diagram of still another embodiment of the present invention.
In a configuration substantially similar to that shown in the figure, a rack 45 and a pinion 46
Instead, a cam follower 61 and a cam 62 are provided to move the piston of the cylinder 44, and the pressing load of the blank holder can also be controlled in this way.

FIG. 6 is an explanatory diagram of another embodiment of the present invention, which has a configuration substantially similar to that of FIG. The piston of the cylinder 44 is moved, and the presser load on the blank holder can also be controlled in this way.

It should be noted that the present invention is not limited to the above-mentioned embodiments (
The mechanical driving means for the pressure control cylinder is arbitrary, the shape of the rotating body in FIG. 2 is arbitrary, and the phase of the rod pivotally connected to the rotating body with respect to the crankshaft is arbitrary; Of course, various changes can be made without departing from the gist of the invention.

[Effects of the Invention] As described above, according to the hydraulic chamber load control device of the present invention,
Since a mechanical drive means is connected to the piston rod of the pressure control cylinder, there is no need for servo valves, etc., making oil management unnecessary, and the excellent effect of controlling the presser load of the plank holder can be achieved. .

[Brief explanation of the drawing]

Fig. 1 is an explanatory diagram of one embodiment of the present invention, Fig. 2 is an explanatory diagram of the mechanical drive means in Fig. 1, and Fig. 3 is an explanatory diagram of the pivoting part of the rotating body and rod in Fig. 2. , FIG. 4 is an explanatory diagram of another embodiment of the present invention, FIG. 5 is an explanatory diagram of yet another embodiment of the present invention, FIG. 6 is an explanatory diagram of another embodiment of the present invention, and FIG. 7 is an explanatory diagram of another embodiment of the present invention. is an explanatory diagram of the principle of a double-acting mechanical press, Fig. 8 is an explanatory diagram of an example of a conventional hydraulic chamber load control device, and Fig. 9 is a diagram showing the relationship between the presser load of the blank holder and the rotation angle of the crankshaft. It is. In the figure, 2 is a crankshaft, 3 and 4 are pitmen, 5 is an inner slide, 6 is a punch, 8 is a holding plate, 9 is a blank holder, 10 is a cylinder for overload prevention, 11 is a piston, and 12 is a hydraulic chamber , 36 is a pipe, 37 is a hydraulic pump, 42 is a pipe, 44 is a cylinder for pressure control, 45 is a rack, 46 is a pinion, 48 is a lever, 49 is a rotating body, 52 is a drive device, 58 is a screw , 54 is a slide, 55 is a rod, 56 is a drive device, 61 is a cam follower, θ2 is a cam, and 63 is a bracket.

Claims (1)

[Claims] 1) A hydraulic chamber load control device, characterized in that a hydraulic chamber on the head side of a pressure control cylinder is communicated with the hydraulic chamber, and a mechanical drive means is connected to a piston rod of the pressure control cylinder. .