JPH03230838A - Punch stroke adjusting device for closed forging die set - Google Patents

Abstract

PURPOSE:To reduce the damage of a relief valve and to prolong its life by providing a debooster cylinder between oil chambers for supporting a punch and the relief valve. CONSTITUTION:In pressurizing and forming a work W, when the volume of the work W is larger than the volume of an closed space formed by an upper die 12 and a lower die 11 in the fall of a slide 23, the volumes of the oil chambers 29a, 34a for supporting the punch reduce gradually and the pressure rises. Therefore, the pressures of oil chambers 3b, 3d on the hydraulic source side are reduced by the debooster cylinders 1, 3 compared with the pressures of the oil chambers 3a, 3c on the press side or the oil chambers 29a, 34a for supporting the punch and relieved by a pressure relief means to stop the punches 13, 14 from moving. Consequently, the damage of the relief valve 16 can be reduced and its life can be prolonged.

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> The present invention relates to a punch stroke adjustment device for a die set for closed forging.

<Prior Art> FIG. 2 is a longitudinal sectional view showing an example of a conventional hydraulic system for a die set for closed forging.

As shown in FIG. 2, the fixed base 22 has a fixed side die 2.
9 is fixedly installed, and an outer piston 25, an inner piston 27, and a rod 48 are slidably installed inside this fixed side die 29. A lower mold 11 is fixed to the upper end of the outer piston 25, and a punch 13 that slidably engages with the lower mold 11 is fixed to the upper end of the rod 48.

Further, a movable die 34 is fixed to the slide 23, and an outer piston 30 and an inner piston 32 are installed inside the movable die 34. An upper mold 12 is fixed to the lower end of the outer piston 30, and a punch 14 that slidably engages with the upper mold 12 is fixed to the lower end of the inner piston 32.

Upper and lower outer pistons 25.30 and inner pistons 27
, 32 respectively defined by hollow holes 26, 31
The accumulator 49 for the pull pack is connected to the hydraulic circuit 3.
5.36, respectively. Also, hard 3
- The lower chamber 29a defined by the foot die 29, the outer piston 25 and the inner piston 27, and the lower chamber 34a defined by the movable die 34, the rear piston 30 and the inner piston 32 are equipped with a hydraulic pressure generator. 20 are connected via a check valve 19 and a relief valve 21, respectively.

Furthermore, the fixed side die 29 is connected to each other by a closed hydraulic circuit 38, and a piston 37 and a tuning piston 41 are installed therein, and an accumulator 40 for pullback is connected below the tuning piston 41 by a hydraulic circuit 42. There is.

Here, the MW stroke amount of the outer piston 25.30 is Δh1. It is configured to be close to Δh2.

In addition, the distance A1 between the upper mold = 4-12 and the lower mold 11, the distance B1 between the outer piston 30 and the tuning piston 41, and the distance C between the movable die 34 and the piston 37 are configured to have the same dimensions. ing. In addition, 50 in the figure is a knockout rod used at the time of mold release.

With this structure, when the material W is loaded into the lower mold 11 and the slide 23 is lowered in the closing direction shown by arrow A, the upper mold 12 joins to the lower mold 11 and the closed space is closed. formed, and as the slide 23 moves further down, the distance between the fixed die 29, the movable die 34 and the respective outer pistons 25° and 30 in the upper and lower oil chambers 29a and 34a,
h is pinched, and the lower inner piston 27, rod 48 and punch 13 and the upper inner piston 32 and punch 14 move in the directions shown by the arrows. Due to the relative approach of both punches 13 and 14, the closed space is reduced, and the material W is pressurized and formed into a finished product.

At this time, the pressure generated in the upper and lower hollow holes 26.31 passes through the hydraulic circuits 35.36 to the accumulators 49 and 31, respectively.
will be returned to.

Then, at the same time as the upper mold 12 contacts the lower mold 11, the movable die 34 contacts the piston 37, and the tuning piston 41 also contacts the upper and lower outer pistons 30.25. As the slide 23 further descends, the piston 37 and the tuning piston 41 move downward.

During this movement, the tuning piston 41 continues to be in contact with the upper and lower outer pistons 30.25, respectively, and the upper and lower oil chambers 29a, 3
The upper and lower outer pistons 25° 30, inner pistons 27, 32, and rod 48 become one body due to a pressure difference in 4a.
Prevents excessive stroke either up or down.

At this time, pressure is generated in the closed hydraulic circuit 38 due to the difference in pressure receiving area and movement distance between the piston 37 and the tuning piston 41, and this pressure is approximately balanced with the pressure of the accumulator 40. That is, the force that restricts upward overstroke is the pressure of the closed hydraulic circuit 38, and the force that restricts downward overstroke is the pressure of the accumulator 40.

When press-forming the material W described above, the slide 2 described above is
The punches 13 and 14 are struck so that the volume of the minimum closed space at the bottom dead center of 3 and the volume of the material W are approximately equal.
is set. Therefore, if the volume of the material W is larger than the closed space due to the error, the oil chamber 29a
, 34a is about to rise excessively, the pressure is relieved by the relief valve 21, and the punch 13.
14 strokes are adjusted.

Next, when the slide 23 is raised in the opening direction, all the pistons 25, 27, 30, 32, 37, 41 return to their original positions due to the pressure stored in the accumulator 40, 49, and the upper mold 12 is the lower mold 1
1 and into an open state, the rod 48 and punch 13 are raised upward by the knockout rod 50, and the product obtained by pressure-molding the material W is discharged from the lower mold 11.

At this time, when the oil pressure in the oil chambers 29a, 34a is relieved, the volume of the oil chambers 29a, 34a becomes smaller and the outer piston 25.
30 does not return to its original position, the oil chambers 29a and 34a are replenished with oil pressure by both oil pressure generators 20, respectively, and the outer pistons 25 and 30 are returned to their original positions as shown in FIG.

<Problems to be Solved by the Invention> However, with conventional devices, there is an error between the volume of the material and the calculated volume of the closed space at the bottom dead center of the slide. (Accordingly, the total volume of the oil chamber becomes smaller, so the pressure in the oil chamber during pressure molding is, for example, 500 kg-f/c, which is the normal pressure in the oil chamber.)
The pressure will be high, greatly exceeding /, and if the volume error is large, the pressure will increase as it approaches the bottom dead center. If this high-pressure hydraulic pressure is relieved by a relief valve, the relief valve will be severely damaged and its life will be shortened, and each time it is relieved, the oil chamber must be replenished with hydraulic pressure, which increases the capacity of the hydraulic power source. For this reason, if a hydraulic power source with an accumulator is directly connected to the oil chamber, a high-pressure hydraulic power source will be required, and there will be a limit to the pressurizing force.

Additionally, if the shape of the product is complex, a fairly high pressure is required to fill the material up to the corners of the closed space.
It is difficult to make the relief pressure in the oil chamber exactly the same as this pressure, and if the relief pressure is low, the stroke of the punch will be insufficient, and if the relief pressure is high, unreasonable force will act on the oil chamber, hydraulic circuit, etc.

Means for Solving the Problems> In order to solve the above problems, the present invention has a structure in which a fixed die is mounted on a fixed base of a reciprocating press, a movable die is mounted on the same slide, and metal is attached to both dies. In a die set for closed forging equipped with a mold and a punch, a pressure reducing cylinder is provided in which the area of the pressure receiving surface on the hydraulic pressure source side of the piston is larger than the area of the pressure receiving surface on the press side, and the press side oil chamber of the pressure reducing cylinder is connected to the die. A set of punch support oil chambers,
In addition, the hydraulic source side oil chambers are connected to the hydraulic source through pressure relief means with a set pressure lower than the pressure of the punch supporting oil chamber, and the fixed side die is connected to the fixed base of the reciprocating press. Attach each movable side die to the slide,
In a die set for closed forging in which both dies are equipped with a mold and a punch, the area of the pressure receiving surface on the hydraulic source side of the piston is larger than the area of the pressure receiving surface on the press side (and A pressure reducing cylinder is provided with a piston movement adjusting means for adjusting the movement amount of the cylinder, and the press side oil chamber of the pressure reducing cylinder is used as the oil chamber for supporting the punch of the die set, and the oil pressure source side oil chamber is used for supporting the punch. A special application characterized in that they are each connected to a hydraulic power source via a pressure relief means with a set pressure lower than the pressure in the oil chamber. According to the above structure, during pressure forming of the material, during the descent of the slide, If the volume of the material is larger than the volume of the closed space, the pressure in the punch support oil chamber will rise above the specified value.
The pressure in the oil chamber on the oil pressure source side is lowered by the pressure reducing cylinder than the pressure in the press side oil chamber, that is, the punch supporting oil chamber, and the movement of the punch can be stopped by relief by the pressure relief means.

In addition, when the pressure in the punch support oil chamber rises during pressure forming of the material, the piston of the pressure reducing cylinder moves toward the oil pressure source side to lower the pressure, and the pressure relief means relieves the punch. When the movement of the piston is stopped by the piston movement adjustment means, the punch moves again and pressurizes the material, thereby filling the corners of the closed space with the material. At this time, if the slide is still descending, the pressure in the punch support oil chamber will increase significantly, so the pressure is lowered by the secondary pressure cylinder and relieved by the secondary pressure relief means. Also good.

Embodiment Hereinafter, an embodiment of the present invention will be specifically described with reference to FIG. Note that the same members and parts as those of the conventional device are given the same reference numerals, and redundant explanations will be omitted.

In FIG. 1, reference numeral 1 denotes a lower pressure reducing cylinder, in which a piston 2 is installed, and a press side oil chamber 1a is formed between the press side pressure receiving surface 2a and the lower pressure reducing cylinder 1. This press side oil chamber 1a is connected to the fixed side die 2 by a hydraulic circuit 8.
The oil pressure source side oil chamber 1b is connected to the accumulator 15 and the oil pressure generator 10 via the check valve 19 and the relief valve 16.

Reference numeral 3 designates an upper pressure reducing cylinder, in which a primary piston 4 and a secondary piston 5 are installed, press side pressure receiving surfaces 4a, 5a = 12- and hydraulic source side pressure receiving surfaces 4b, 5b of each piston 4, 5, Press side oil chambers 3a, 3c and oil pressure source side oil chambers 3b, 3d are formed between the upper pressure reducing cylinder 3 and the upper pressure reducing cylinder 3, respectively.

These press side oil chambers 3a, 3c are hydraulic circuits 9a, 9.
b, connected to the lower chamber 34a of the movable die 34 by 9, and a hydraulic source side oil chamber 3b.

3d primary leaf valve 17, secondary leaf valve 1
8 and a check valve 19 to an accumulator 15 and a hydraulic pressure generator 10 .

Then, the hydraulic pressure source side pressure receiving surface 2 of each piston 2, 4.5
The diameters of b, 4b, and 5b are the press side pressure receiving surfaces 2a, 4a, and 5.
It is larger than the diameter D of a. A nut 6 is fixed to the upper and lower pressure reducing cylinders 1.degree. 3, and a movable stopper 7 is screwed into this nut 6.

Next, the operation of this device will be explained.

When the material W is loaded into the lower mold 11 and the slide 23 is lowered in the closing direction shown by arrow A, the upper mold 12 is moved into the lower mold 11.
A closed space is formed by joining the Further slide 23
As the lowering progresses, the upper and lower outer pistons 25 and 30 move as shown by the arrows, and the lower inner piston 27, rod 48 and punch 13 and the upper inner piston 32 and punch 14 move as in the conventional device. move closer to each other, the closed space is reduced, and the material W is pressurized and molded into a finished product.

At this time, if the volume of the material W is larger than the volume of the closed space at the bottom dead center of the slide, the upper and lower outer pistons 2
5.30 continues to move to the bottom dead center of the press, but punch 1
3, 14, the rod 48, and the inner pistons 27, 32 stop moving before then, as the slide 23 descends, the volumes of the lower oil chamber 29g and the lower chamber 34a gradually become smaller, and the pressure thereof increases.

The relief pressure of the secondary leaf valve 18 is equal to that of the other relief valve 1.
The pressure in the stage chamber 29a first enters the press side oil chamber 1a of the lower pressure cylinder 1 and presses the press side pressure receiving surface 2a of the piston 2.
The pressure in the performance chamber 34a enters the press side oil chamber 3a of the lower pressure cylinder 3 via the hydraulic circuits 9, 9a and presses the press side pressure receiving surface 4a of the primary piston 4. Both pistons 2, 4
While moving toward the oil pressure source side, each oil chamber 1b on the oil pressure source side
.

3b, the relief valve 16 and the primary leaf valve 1
When the pressure is relieved from 7, both inner pistons 27, 32 stop moving. This pressure can be adjusted by adjusting the position of the stopper 7 in the press side oil chambers 1a and 3a.
The movement of the piston 2 and the primary piston 4 is controlled by the slide 23.
If the inner pistons 27 and 32 and the punches 13 and 14 are stopped before reaching the bottom dead center, both inner pistons 27 and 32 and punches 13 and 14 start moving again. Since the pressure in the upper and lower oil chambers 29a, 34a increases again (15-), the pressing force of the punches 13, 14 against the material W is strong, and the material W is filled up to the corners of the closed space.

When the molding of this material W into a finished product is completed, if the slide 23 has not yet reached the bottom dead center, the upper and lower oil chambers 29a
, 34a further increases, and this pressure presses and moves the press side pressure receiving surface 5a of the secondary piston 5,
A leaf valve 1 that secondaryizes the reduced pressure in the oil chamber 3d on the oil pressure source side.
Relief from 8.

When the closed forging is completed and the slide 23 passes the bottom dead center and rises, the amount of oil relieved from the relief valves 16, 17° 18 is transferred to the oil pressure source side oil chambers 1b, 3b by the oil pressure generator.
, 3d and return the outer piston 25.30 to the position shown.

As described above, according to this embodiment, the strokes of the punches 13 and 14 can be easily adjusted by changing the position of the movable stopper 7 while checking the quality of the finished product during forging. Further, in some cases, the secondary piston 5 and the secondary leaf valve 18 may not be provided.

<Effects of the Invention> As described above in detail, according to the present invention, by providing the pressure reducing cylinder between the punch support oil chamber and the relief valve, the punch support oil chamber is removed during pressure forming of the material. Even if the pressure becomes high, the relief valve can provide relief at a pressure lower than that pressure, which reduces damage to the relief valve and extends its life.

Further, according to the present invention, by providing the piston movement amount adjusting means for adjusting the amount of movement of the piston toward the hydraulic pressure source side in the decompression cylinder, the punch stroke can be easily adjusted during pressure forming of the material. Even if the shape of the product (closed space) is complex, the material can be filled to every corner of the closed space, and the occurrence of defective products can be reduced.

[Brief explanation of drawings]

FIG. 1 is a longitudinal sectional view of a die set for closed forging as an embodiment of the present invention, and FIG. 2 is a longitudinal sectional view showing an example of a conventional die set for closed forging. In Fig. 1, 1...lower range pressure cylinder, 1a...press side oil chamber, 1
b...Oil pressure source side oil chamber, 2...Piston, 2a press side pressure receiving surface, 2b...hydraulic source side pressure receiving surface, 3...lower range pressure cylinder, 3a/3c - press side oil chamber , 3b・3d
...Hydraulic pressure source side oil chamber, 4. Primary piston, 4a...Press side pressure receiving surface, 4b...Hydraulic pressure source side pressure receiving surface, 5...2
Next piston, 5a...Press side pressure receiving surface, 5b...Hydraulic pressure source side pressure receiving surface, 6...Nut, 7...Movable stopper, 10...Hydraulic pressure generator, 11...Lower mold , 12・
...Upper mold, 13, 14... Punch, 16... Relief valve, 17... Primary relief valve, 18... Secondary relief valve, 22... Fixed pace, 23... Slide, 25/30... Outer piston, 27/32 Inner piston, 29... Fixed side die, 29a... Lower pond chamber, 34... Movable side die, 34a... Stage room, W...
·material.

Claims (2)

[Claims] (1) In a die set for closed forging, in which a fixed die is attached to the fixed base of a reciprocating press, a movable die is attached to the same slide, and a die and a punch are attached to both dies, the oil pressure source side of the piston A pressure reducing cylinder with a pressure receiving surface area larger than that of the press side pressure receiving surface is installed.
The press-side oil chamber of the pressure reducing cylinder is connected to the punch-supporting oil chamber of the die set, and the hydraulic source-side oil chamber is connected to the hydraulic source via pressure relief means having a set pressure lower than the pressure of the punch-supporting oil chamber. , a punch stroke adjustment device for a die set for closed forging, characterized in that they are connected to each other. (2) In a die set for closed forging, in which a fixed die is attached to the fixed base of a reciprocating press, a movable die is attached to the same slide, and a die and a punch are attached to both dies, the hydraulic pressure source side of the piston receives pressure. A pressure reducing cylinder having a surface area larger than the area of the press side pressure receiving surface and having a piston movement adjustment means for adjusting the movement amount of the piston toward the oil pressure source side is provided, and the press side oil chamber of the pressure reduction cylinder is provided. The punch supporting oil chamber of the die set and the hydraulic source side oil chamber are connected to a hydraulic power source through a pressure relief means having a set pressure lower than the pressure of the punch supporting oil chamber. Punch stroke adjustment device for closed forging die sets.