JPS6054808B2 - Double sink integral molding method - Google Patents

Description

[Detailed description of the invention] The present invention relates to a double zinc integral molding method.

A so-called double zinc product, which has a pair of parallel zincs, as shown in Figure 1 A, is made into one piece of material (blank).
Integrally molding from a material is very effective in reducing the number of processing steps and improving material yield. However, in the conventional method, it was not possible to mold the zinc deeply because the A part was easily broken. The reason for this is as follows. That is, the material for forming the central side wall B cannot flow from the portion C because the pair of zincs are adjacent to each other. Therefore, the material forming the central side wall B must flow from the bottom wall D and side wall E, but it cannot flow smoothly due to friction with the punch. This friction is particularly large at the periphery of the punch bottom, and the force that squeezes the material at section F is transmitted to section A with the addition of the frictional force of the periphery of the punch bottom that acts on sections G and H. Therefore, the stress at part A becomes maximum, and it breaks at this part. By the way, the present inventors have already developed a double zinc integral molding method (Japanese Patent Application No. 55-9809) that solves the above problem.
time) was proposed. This integral molding method is a molding method in which, during molding, the punch is pushed in while increasing the liquid pressure at the bottom of the punch using a pump, and the punch is lowered to a predetermined position while removing the pressure liquid. Therefore, according to this integral molding method,
Since there is a relationship between the punch stroke and the hydraulic pressure at the bottom of the punch, there is a drawback that a pressure control mechanism and a pump are required. In view of the above-mentioned points, the present invention provides a double zinc integral molding method that allows the zinc to be drawn deeply and eliminates the need for a pump and pressure control mechanism by reducing the frictional force between the punch and the blank. An example of this will be described below with reference to the drawings.

In FIG. 2, a fixed die 1 has a partition wall 2 in the center and die holes 3a and 3b formed on both sides.

4 is the elevating body on the press side, 5a and 5b are the dice 3a,
A punch corresponding to 3b, 6 a blank holder disposed outside the punches 5a and 5b, and 7 a blank.

A pair of pressure chambers 9a, 9b are formed in the elevating body 4, and the upper ends of the punches 5a, 5b slide in the vertical direction into the pressure chambers 9a, 9b. It is movably fitted inside. 10 is the pressure chamber 9a, 9
b is a hole that communicates with the outside of the elevating body 4, and the hole 1
A supply channel 12 for supplying the liquid in the liquid storage phase 11 to the pressure chambers 9a, 9b, and a return channel 13 for returning the liquid in the pressure chambers 9a, 9b to the liquid storage tank 11 are connected to 0. ing.

The pair of punches 5a and 5b have a cross-sectional area larger at the upper end than the other part, and have a through hole 14 along the vertical direction.
a, 14b are formed. 15a, 15b are located inside the die holes 3a, 3b and are inserted into the punches 5a, 5.
It is a bottom press plate facing the punch bottom of b, and the bottom press plate 1
5a and 15b are lifting rods 16a passing through the die 1;
It is fixed to the upper end of the lifting rod 16a, 16b.
b can be moved up and down a predetermined distance and is urged upward with a predetermined force.

Note that 17 is a valve provided in the supply flow path 12;
19 is a relief valve provided in the return flow path 13; 19 is a lid body fixed to the lower surface of the elevating body 4 to prevent the punches 5a, 5b from coming out of the pressure chambers 9a, 9b; 20;
a, 20b are sealing devices for sealing between the punches 5a, 5b and the elevating body 4; 21a, 21b are the punches 5;
A sealing device 22 seals between the blank holder 6 and the blank holder 6; This is a sealing device. When integrally molding a double sink, the blank 7 is first placed on the die 1 and tightened by applying a predetermined wrinkle pressing force Q using the blank holder 6.

Next, the punches 5a and 5b are inserted into the blank holder 6, and the elevating body 4 is lowered with the pressure chambers 9a and 9b filled with liquid. As a result, a hydraulic pressure p is generated in the pressure chambers 9a and 9b. Since the liquid in the pressure chambers 9a, 9b is also filled between the punch bottom and the blank 7 through the through holes 14a, 14b of the punches 5a, 5b, the liquid pressure p acts on the blank 7, and the blank 7 begins to narrow down. At this time, a force F3 corresponding to the difference between the cross-sectional area A2 of the upper end portion and the cross-sectional area A1 of the other portion acts on the punches 5a and 5b,
Punches 5a and 5b are pushed downward. This cross-sectional area A
The difference between 1 and A2 is set so that a force F3 acting on the punches 5a and 5b can correct to some extent the rounded portions of the four corners of the zinc bottom wall after being squeezed by the hydraulic pressure p. Further, bottom pressing plates 15a and 15b are applied to the lower surface of the zinc bottom wall to prevent the zinc bottom wall from being formed into a spherical shape. After the molding progresses and the lifting rods 16a and 16b reach their lower limit,
When the elevating body 4 is further lowered, the liquid pressure p continues to rise, but at a predetermined pressure P. When the pressure is reached, the relief valve 18 operates to maintain a constant pressure. At this time, punches 5a and 5b do not descend. Therefore, the volume of the pressure chambers 9a, 9b decreases, the upper walls of the pressure chambers 9a, 9b and the upper end surfaces of the punches 5a, 5b come into contact with each other, and the punches 5a, 5b are directly pushed by the elevating body 4, and the punches The liquid between the bottom and the blank 7 flows through the through holes 14a, 14b1, the pressure chambers 9a, 9b, and the return channel 13.
The liquid is returned to the liquid storage tank 11 via. At this time, the uneven "R" of the four corners of the zinc bottom wall during hydroforming is caused by the punch 5a.
, 5b. Forming is completed by lowering the elevating body 4 until the punch bottom comes into contact with the upper surface of the zinc bottom wall. In this way, the blank 7 is squeezed by the hydraulic pressure p of the liquid between the punch bottom and the blank 7, so
The contact area between the punches 5a, 5b and the blank 7 is small,
Furthermore, since the friction between the bottom press plates 15a, 15b and the blank 7 is a flat surface sliding and the frictional force is small, the material flows smoothly into the central side wall B in FIG.

Further, since the central side wall B is pressed against the wall surface of the partition wall portion 2 of the die 1 by the hydraulic pressure p, the stress in the portion A is reduced due to the frictional holding effect. Therefore, even if the zinc is squeezed deeply, there is no fear that the A portion will break. Further, by pressing the punches 5a and 5b with appropriate force, wrinkles can be prevented. Also, press the punch 5a until the bottom of the punch comes into contact with the top surface of the zinc bottom wall.
, 5b, the four corners of the zinc bottom wall can be formed accurately. Further, the saw body can be formed by an extremely simple operation of filling the pressure chambers 9a, 9b with liquid and lowering the elevating body 4. By the way, the cross-sectional area of the upper ends of the punches 5a and 5b is A2, the cross-sectional area of the other parts is A1, and the blank 7 and the bottom presser plate 15a or 15.
b is the contact area and the hydraulic pressure is p, then the force F1 for lowering the elevating body 4 is the bottom pressing force F2, the punch thrust F3 is the squeezing force Pp generated on the blank 7 by the liquid pressure, and the total squeezing force is P
There is a limit.

In the above embodiment, after the lifting rods 16a and 16b have descended to the lower limit, the liquid is released through the relief valve 18 to maintain the pressure in the pressure chambers 9a and 9b at PO. 18 may be omitted and the opening may be completely opened.

Further, in the above embodiment, an example has been described in which the bottom press plates 15a, 15b are fixed to the lifting rods 16a, 16b which can be raised and lowered by a predetermined distance. It may be fixed to a certain limit. Furthermore, when squeezing the blank 7 using the hydraulic pressure p, if a compression force is applied to the outer circumference of the blank 7 to compress the blank 7 in the direction between the punches, the flow of material toward the central side wall B can be made even smoother. can do.

Furthermore, if the bottom press plates 15a and 15b are made of, for example, an endless belt and are movable toward the partition wall 2 side of the die 1, the frictional force between the blank 7 and the bottom press plates 15a and 15b can be eliminated. can.

As explained above, according to the double sink integral molding method according to the present invention, the blank is squeezed by the hydraulic pressure of the liquid between the punch bottom and the blank, so the frictional force between the punch bottom and the blank is reduced. Due to the smooth flow of the material into the center side wall and the frictional holding effect acting on the center side wall, the bent portion at the upper end of the center side wall is difficult to break, and therefore the zinc can be narrowed deeply. Further, by using a punch, it is possible to prevent the occurrence of wrinkles and also to form the four corners of the zinc bottom wall accurately. Furthermore, according to the forming method of the present invention, since the upper end of the punch is fitted into the pressure chamber, hydraulic pressure is automatically generated at the lower end of the punch as the elevating body descends, and this hydraulic pressure and the upper and lower ends of the punch are The pushing force of the punch is proportional to the area difference between the parts, and therefore no special pressure control mechanism or pump is required.

[Brief explanation of drawings]

FIG. 1A is a plan view of the double sink product, the opening in the same figure is a longitudinal sectional front view, and FIG. 2 is a longitudinal sectional front view showing one embodiment of the present invention. 1...Dice, 3a, 3b...Dice hole, 4...Elevating body, 5a, 5b...Punch, 6...Blank Holder, 7...
・Blank, 9a, 9b... Pressure chamber, 14a,
14b...Through hole.

Claims (1)

[Claims] 1. When molding a pair of parallel sinks, a pair of punches that have a through hole along the vertical direction and a cross-sectional area of the upper end part is larger than the cross-sectional area of the part inserted into the die hole, and A supply channel having a pair of pressure chambers whose upper end portions are fitted inside so as to be slidable in the vertical direction, and a check valve provided in the middle for supplying liquid from the liquid storage tank into each of the pressure chambers; Using an elevating body that is provided with a relief valve and connected to a return flow path for returning the liquid in each pressure chamber to the liquid storage tank, a blank is held between a die and a blank holder, and the pair of punches are inserted into the blank. A method for integrally molding a double sink, characterized in that the pressure chamber is filled with liquid while the elevating body is lowered while inserted into a holder.