JPH05245546A - Method for shaping sheet metal by hydraulic forming method - Google Patents

Abstract

PURPOSE: To shape a sheet metal into a complicated shape by simple shaping work. CONSTITUTION: This method is provided with a first process during which a blank holder 1 is brought into contact with a sheet metal 2 supported on a die 3 having a cavity 4, a second process in which a pressurized liquid is fed by means of a first hydraulic circuit to the cavity 4 in the die 3 below the sheet metal 2 and a third process in which a punch 7 is displaced toward the sheet metal 2 to plastically deform the sheet metal 2 through the combined action of the pressure generated by the punch 7 and the pressurized liquid. A second pressurized liquid delivered from a second hydraulic circuit is caused to act on the upper surface 9 of at least a part 10 of the sheet metal 2 and is balanced with the pressure acting on the under surface 11 of the part 10 while the punch 7 is displaced in order to deform the sheet metal 2.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for forming a sheet metal by a hydraulic forming method.

[0002]

2. Description of the Related Art As a method of forming a thin sheet metal by a hydraulic forming method, a first step of bringing a wrinkle retainer into contact with a thin sheet metal supported on a forming die having a recess. , A second step of sending the pressurized liquid to a recess under the sheet metal by a first hydraulic circuit, and a third step of moving the punch toward the sheet metal to plastically deform the sheet metal. The method is known. The deformation of the sheet metal in the third step is performed by the combined action of the pressure generated on the upper surface of the sheet metal by the punch and the pressure generated on the lower surface of the sheet metal by the pressurized liquid.

However, the above method has the following problems. That is, it cannot be pressed into a relatively complex shape by a single molding operation, and requires multiple continuous molding operations performed using different pressing machines and dies.

In fact, when the shape of the punch required to obtain the molding effect is such that it does not immediately contact the upper surface of the sheet metal during the first stage of the punch stroke,
A space or chamber is formed between the outer surface of the punch, the inner side of the wrinkle retainer, and the sheet metal itself. The size of this space or chamber decreases as the punch stroke continues. The pressure of the pressurized liquid described above acts on the lower surface of the sheet metal, but this pressure is not balanced by any other pressure acting on the upper surface of the sheet metal. Therefore, the deformation of the thin sheet metal, which is the boundary of these spaces, progresses uncontrolled, and during the stroke, cracks due to the high stress induced in the thin sheet metal due to the influence of the pressure of the pressurized liquid are likely to occur.

In order to avoid such a problem, many steps must be carried out by various machines and presses in actual molding.

An object of the present invention is to provide a method capable of forming a sheet metal into a complicated shape over a wide range by a single forming operation without the above-mentioned drawbacks.

[0007]

A method for forming a sheet metal by a hydraulic forming method according to the present invention comprises a first step of bringing a wrinkle retainer into contact with a sheet metal supported on a forming die having a recess. The second step of sending the pressurized liquid to the recess under the sheet metal by the first hydraulic circuit, the pressure generated on the upper surface of the sheet metal by the punch by moving the punch toward the sheet metal, and the sheet metal by the liquid. Is a method of forming a thin sheet metal by a hydraulic forming method, which includes a third step of plastically deforming the sheet metal by a combined action with a pressure generated on the lower surface of the punch, in which the punch moves to deform the sheet metal in the third step. Characterized in that the second pressurized liquid sent by the second hydraulic circuit acts on the upper surface of at least a part of the sheet metal during the operation and balances the pressure acting on the lower surface of the part. Is.

[0008]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1, FIG. 2 and FIG. 3 show a continuous form of the punch and the sheet metal in the process of forming the sheet metal.

According to the method of the present invention, the wrinkle retainer (1) is
It includes a first step of contacting a sheet metal (2) supported on a forming die (3) having an appropriately shaped recess (4). During the first step of the method, the wrinkle retainer (1) exerts a predetermined pressure on the edge (5) of the sheet metal (2), leaving the recess (4) substantially liquid-tight. It is sealed to. Furthermore, the present invention includes second and third steps.

In the second step of the method of the present invention, the first pressurized liquid consisting of water, oil, etc. is dented by a first hydraulic circuit (not shown) under the lower surface (6) of the sheet metal (2). It is supposed to be sent to the place (4). Also, in the third step of the method of the present invention, as shown in FIG.
It is designed to move towards the recess (4) in order to deform (2). During this third step, the pressure exerted by the punch (7) on the upper surface (8) of the sheet metal (2) and the lower surface (6) of the sheet metal (2) by the liquid filled in the recess (4). The sheet metal (2) is plastically deformed by the combined action with the pressure generated on. Pressurized liquid can be removed from the recess by suitable means not shown.
It is clear that the pressure is maintained within (4).

According to the present invention, the second pressurized liquid consisting of water, oil or the like sent by the second hydraulic circuit (not shown) is applied to the upper surface (9) of at least a part (10) of the sheet metal (2). To balance with the pressure acting on the lower surface (11) of the portion (10) of the sheet metal (2).

As shown in FIG. 1, the second pressurized liquid is the lower surface of the punch (7), the surface of the wrinkle retainer (1), and the upper surface (9) of the above portion (10) of the sheet metal (2). Chamber formed by and (1
Sent to 2). The second pressurized liquid is also sent to the chamber (12) when the punch (7) reaches a predetermined position in its stroke and starts to deform the sheet metal (2). The second pressurized liquid is sent to the chamber (12) by the conduit (13) provided in the wrinkle retainer (1). The conduit (13) is a stop valve that is switched between a first position where the conduit (13) communicates with a second source of pressurized liquid (not shown) and a second position that allows discharge of the second pressurized liquid. A chamber (12).
The pressure of the liquid inside is maintained at a predetermined pressure. The stop valve (14) is provided with means for providing the desired resistance to the flow of the second pressurized liquid, whereby the punch (7) is a sheet metal.
While the stroke for plastically deforming (2) is completed, the inside of the chamber (12) is maintained at the above predetermined pressure.

As shown in FIG. 2, when the stroke of the punch (7) for further deforming the sheet metal (2) is completed, the deformation of the sheet metal (2) increases and the surface of the punch (7) increases. Try to stick to. During the deformation of this sheet metal (2) the chamber
The pressure of the second pressurized liquid filled in (12) and the pressure of the first pressurized liquid filled in the recess (4) are still punched, respectively.
The upper surface (9) of the part (10) of the sheet metal (2) not in contact with (7)
And on the underside (11). When these pressures are substantially equal, the part (10) is in perfect balance, so that there is no force trying to deform this part (10). As a result, the deformation of the punch (7) during molding continues even if the depth of molding is extremely large and the shape of the punch (7) is rather complicated.

When the stroke of the punch (7) advances, the second pressurized liquid is discharged from the chamber (12) through the valve (14), and the pressure in the chamber (12) is kept constant by the action of the valve (14). Maintained at. When the punch (7) reaches the stroke end of its forming stroke, as shown in FIG.
The upper surface (8) (9) of the sheet metal (2) is in full contact with the corresponding surface of the punch (7). In this state, the chamber (1
The second pressurized liquid filling the inside of 2) is completely discharged through the conduit (13).

To assist in completing the forming stroke of the punch (7), it is preferable to provide the punch (7) with a small size auxiliary chamber (15), for example, as shown. In this way, when the punch (7) is in the stop position at the stroke end shown in FIG. 3, the auxiliary chamber (1
5) is still in communication with the conduit (13) and the punch (7) allows the conduit (1
Excessive pressure rise of the second pressurized liquid due to blockage of 3) is avoided. Moreover, since the volume of the auxiliary chamber (15) is small, it does not affect the characteristics of the morphology and shape of the semi-finished product obtained by molding the sheet metal (2).

Modifications and variations can be made to the method described above without departing from the scope of the invention.

[0018]

According to the method of the present invention, while the punch is moving to deform the sheet metal in the third step of the hydraulic forming method, the second hydraulic circuit feeds the second hydraulic circuit.
Is applied to the upper surface of at least a part of the sheet metal and balanced with the pressure applied to the lower surface of the part, so that the sheet metal can be formed into a complicated shape by a single forming operation. ..

[Brief description of drawings]

FIG. 1 is a vertical sectional view showing an initial stage of forming a sheet metal by a punch.

FIG. 2 is a vertical sectional view showing an intermediate stage of forming a sheet metal by a punch.

FIG. 3 is a vertical sectional view showing a final stage of forming a sheet metal by a punch.

[Explanation of symbols]

 1 Wrinkle retainer 2 Thin sheet metal 3 Forming die 4 Recess 6 Lower surface of thin sheet metal 7 Punch 8 Upper surface of thin sheet metal 9 Upper surface of part of thin sheet metal 10 Part of thin sheet metal 11 Lower surface of part of thin sheet metal

Claims (6)

[Claims] 1. A first means for contacting a wrinkle retainer (1) with a sheet metal (2) supported on a forming die (3) having a recess (4).
Process and pressurizing liquid through the first hydraulic circuit to sheet metal
The second step of sending to the recess (4) under (2), and moving the punch (7) toward the sheet metal (2), and then using the punch (7).
The pressure generated on the upper surface (8) of (2) and the liquid causes the sheet metal (2)
The combined effect of the pressure exerted on the underside (6) of the sheet metal
A method of forming a thin sheet metal by a hydraulic forming method including a third step of plastically deforming (2), wherein a punch (7) is moved to deform the sheet metal (2) in the third step. In between, a second pressurized liquid delivered by a second hydraulic circuit is passed through at least a portion (1) of the sheet metal (2).
A method for forming a thin sheet metal by a hydraulic forming method, which comprises acting on the upper surface (9) of (0) and balancing the pressure acting on the lower surface (11) of the portion (10). 2. A second pressurized liquid is applied to the surface of the punch (7).
Wrinkle foot (1) and the upper surface (9) of the above part (10) of the sheet metal (2)
2. The method of forming a thin sheet metal by the hydraulic forming method according to claim 1, wherein the sheet metal is sent to a chamber (12) formed by. 3. When the punch (7) reaches a predetermined position in the stroke and comes into contact with the sheet metal (2), the second pressurized liquid is sent to the chamber (12), and the second stroke of the punch (7) is changed. The second pressurized liquid is gradually discharged from the chamber (12) during the remaining portion to maintain the pressure in the chamber (12) at a predetermined pressure while reducing the volume of the chamber (12). The method for forming a thin sheet metal by the hydraulic forming method according to claim 1 or 2. 4. A stop valve (14) adapted to deliver a second pressurized liquid to a chamber (12) through a conduit (13) provided in the wrinkle retainer (1) and provided with a stop valve (14).
A first position in which the conduit (13) communicates with a second source of pressurized liquid;
4. The method according to any one of claims 1 to 3, wherein the pressure in the chamber (12) is switched to and from a second position which allows discharge of the second pressurized liquid while maintaining the pressure at a predetermined level. A method for forming a sheet metal by the hydraulic forming method described. 5. The liquid according to claim 1, wherein when the punch (7) reaches the stroke end, the remaining amount in the chamber (12) is maintained so as not to be zero. Sheet metal forming method by pressure forming method. 6. An auxiliary device which comprises a recess formed in a portion of the punch (7) near the outlet of the conduit (13) when the punch (7) reaches the stroke end and communicates with the chamber (12). The method for forming a thin sheet metal by the hydraulic forming method according to claim 5, wherein the chamber (15) contains the remaining amount of the second pressurized liquid.