JPH01162527A - Tool for deep-drawing sheet-shaped metallic part - Google Patents

Abstract

PURPOSE: To move a draw core by the movement of a blank holder and to enable deep-drawing of a metal sheet by cooperating its effective area with an incompressible fluid using the blank holder and a draw core as a piston. CONSTITUTION: A sheet-metal plate is arranged between tools and a matrix 10 is moved in the direction shown by an arrow. First, a free end of the matrix 10 is engaged with the free end of a blank holder ring 22, which is pressurized by the sheet-metal plate. The free end of the matrix 10 is slightly protruded exceeding the free end of the draw core 25, the blank holder ring 22 is pushed downward, a cutting edge 20 is cooperated with the cutting edge 35 of the matrix 10, and the blank is cut from the sheet-metal plate. When the blank holder ring 22 is moved downward, the draw core 25 is slightly lifted. And when the matrix 10 is further moved downward, the draw core 25 is moved upward in accordance with it and united with the matrix 10, whereby deep- drawing is executed.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a tool for deep drawing sheet metal parts as defined in the preamble of claim (1).

Deep drawing is a forming technique for manufacturing hollow objects from flat sheet metal pieces. In the simplest case, a punch or deep-drawing core squeezes the blank against a drawing ring and matrix, thereby forming a hollow. The force required for deep drawing processing is a virtual forming force, which is the frictional force between the embossed ring and the blank holder, the frictional force caused by the runout of the drawing ring, and the rounding of the drawing ring due to bending. This is a straightening force for straightening the slope that appears during machining. Furthermore, a blank holding force is required to allow the blank holder to act at right angles to the surface of the sheet metal. This force is to prevent wrinkling of the flange of the throttle member caused by tangential compressive strain.

It is known to keep the drawing ring and matrix fixed and to manipulate the drawing core and blank holder by means of a press. However, separate handling means for the drawing core and blank holder are required, and such a construction is relatively expensive.

It is also known to date to arrange the deep drawing core and blank holder in a fixed part of the press and to connect the matrix to the press ram. This design requires moving the blank holder together with the matrix in the feed direction and introducing the drawing core into the matrix. A spring assembly engages the blank holder to provide the required sheet metal gripping force. Typically, the spring assembly is formed by a buffer actuator;
When the blank holder moves, the force of the buffer actuator increases, thereby creating the required force on the blank holder so that it can be returned to the starting position during the return stroke of the matrix. This structure has several drawbacks.

It is clear that during the machining stroke, the energy stored in the spring assembly is returned to the system, but as the actuator energy increases, frictional forces cause large losses. The cost of energy for driving the press ram increases accordingly. This fact and the feedback of energy from the actuator to the press ram results in a relatively non-uniform load for driving the press ram. And the uneven driving force causes relatively high wear and shortens the life of the press ram.

It is only when the drawing core has moved sufficiently away from the matrix that the sheet metal plate stamping the blank to be deep drawn can be advanced. The longer the matrix travels, the less time is available for its progression. In other words, the lower the feed rate and overall machining speed of the sheet metal plate, the more time in the machining cycle that can be used for deep drawing. A relatively long machining stroke has the disadvantage that the matrix and blank holder collide at relatively high speeds. This causes distortion of the press.

It is therefore an object of the invention to provide a tool for deep drawing sheet metal parts, which reduces the cost of material and energy consumption and allows a uniform load to be applied to the press.

This object is achieved by what is stated in the characterizing part of claim 1.

In this invention, an active surface connected to a communication system containing an incompressible fluid is connected to the blank holder and the embossed core. In other words, the blank holder and the drawing core are transmission-connected. When the blank holder moves in the direction of the machining stroke of the matrix, the drawing core moves in the opposite direction from the matrix. This deep drawing tool design offers significant advantages.

With the deep drawing tool of the invention, there is no need to increase the energy for the spring actuator acting on the blank holder during the machining stroke. Therefore, the frictional force that has existed up until now no longer exists. A sheet metal blank can be formed by processing using only a press or its drive mechanism. Not only can energy be saved, but the driving forces required for the press rams are significantly more uniform. As before, during the forming stroke, the press ram is not braked abruptly, and during the return stroke, the press ram is not accelerated rapidly.

Therefore, the strain caused in the press is small, its life is long, and wear is small.

The tool of the invention has the advantage that the length of the cloak of the ram driving the matrix is shorter than in conventional tools.

, this reduction in stroke length is brought about by the embossed core coming somewhat closer to the matrix. Because of the short stroke length, more of the cycle time can be used to feed the sheet metal plate, significantly increasing manufacturing speed. Furthermore, due to the short forming stroke, the matrix impinges on the blank holder at low speed, which reduces the load on the press.

A further advantage is that the buffer actuator can be omitted, reducing the cost and overall size of the tool.

Various embodiments of this invention are possible. The blank holder and the drawing core may be connected to the piston and their effective surfaces may cooperate by means of a communication system. In this embodiment, it is particularly easy to separate the tool from the uncompressed fluid so that, in the event of a leak, the uncompressed fluid does not reach the effective surface of the tool and does not affect the deep drawing process.

In another embodiment, the blank holder and the drawing core are formed as pistons. In this embodiment, in particular, an annular blank holder is slidably disposed within the cylinder and sealed, a drawing core is slidably supported within the bore of the blank holder and sealed, and the slider is filled with an incompressible fluid. The whole can be made very compact when Appropriate seals must be provided within the component to prevent leakage of uncompressible fluid into the molding area.

It goes without saying that the communication system must be completely filled with incompressible fluid at all times. The communication system is thus connected to a pressure source of incompressible fluid.

The present invention will be described in detail below.

In the figure, the matrix (lO) is manipulated by the ram of the press (not shown). The matrix (10) is fixed within a sleeve (I2), which is attached to a plate (13) connected to the press ram. The sleeve (12) is a stripper ring (14)
The stripper ring (14) concomitantly surrounds the matrix. The ring (14) is movable relative to the sleeve (12) and the matrix (10).

An ejector pusher (11) is connected to the plate (11a) and is capable of ejecting the molded part in a known manner.

A cup-shaped member (15) is fixed by screws (17) to a plate (16), which is attached to the frame. The upper edge of the cup-like member (15) has a cutting ring (
18). The cutting ring (18) has a cutting edge (2
0). The holes in the cutting ring (18) and the cup-shaped member (15) form a cylinder (21) in which the blank holder ring (22) can slide and be displaced.
2) has a shoulder (23) cooperating with the shoulder of the cutting ring (18).
) to limit upward movement of the blank holder ring (22). A peripheral seal (24) is provided on the outer surface of the blank holder ring, which cooperates with the wall of the cylinder.

The drawing core (25) is inserted into the hole of the blank holder ring (22).
) is reseated, and the upper surface of the drawing core (25) is the cylinder (2
1) is supported on the abutment (26). Inner annular seal (27) of blank holder ring (22)
cooperates with the outer periphery of the drawing core (25). The blank holder ring (22) and the drawing core (25) are therefore designed as a piston, the lower effective surface of which faces the space (21) of the cylinder. Inside the space of the cylinder is an uncompressed fluid (2 days), which is conveyed from a pressure source (29) to a conduit (30) and a bore 31). A check valve (32) is located in the conduit (30). A helical spring (
33), which pulls the drawing core (25) towards the abutment (26).

The operation of this device is as follows. During the molding stroke, the matrix (lO) moves downward in the direction of the arrow (34). A sheet metal plate (not shown) is placed between the tools shown. First, the free end face of the matrix (10) is aligned with the blank holder ring (22).
), the latter being pressurized by the sheet metal plate. Said free end surface protrudes slightly beyond the free end surface of the drawing core (25), the blank holder ring (22) is pushed down a small distance, and the cutting edge (20) is aligned with the cutting edge (20) of the matrix (10). 35), cut the blank from the sheet metal plate. Ring (14) is a cutting ring (18)
It is supported on top and held behind the matrix (lO).

When the blank holder ring (22) moves downward, the drawing core (25) is slightly lifted. When the matrix (lO) further moves downward, the drawing core (25) moves upward accordingly. The blank holder ring (
The downward movement of 22) and the upward movement of the drawing core (25) have an interlocking relationship. As a result, the drawing core (25) is combined with the matrix (lO), and deep drawing processing is performed.

It is clear that the matrix (lO) need only be moved with small strokes relative to a tool with a fixed drawing core.

By varying the effective surface, it is of course possible to vary the ratio of forces on the embossed core (25) and the blank holder ring (22). It is known from experience that the force on the blank holder ring (22) is usually greater than the force on the drawing core, which determines the holding force, and that a relatively short stroke of the blank holder ring (22) A relatively long stroke can be generated. As previously mentioned, this stroke ratio allows for short molding strokes of the matrix (10), which is preferred.

At the end of the deep drawing process, the drawing core is pulled back to the initial position shown by the spring (33),
This causes the blank holder ring (22) to reach its upper, initial position.

[Brief explanation of the drawing]

The drawing is a sectional view of the deep drawing tool of the present invention. (10)・・・・・・・・・・・・・・・・・・
Matrix (21)・・・・・・・・・・・・・・・
・・・・・・Cylinder (22)・・・・・・・・・・・・
・・・・・・・・・Blank holder (25)・・・・
・・・・・・・・・・・・・・・Drawing core (28)
・・・・・・・・・・・・・・・・・・ Incompressible fluid (29)・・・・・・・・・・・・・・・・・・・・・
・Pressure source patent applicant Alfons Bahr Maschinenbau Gesellschaft Mitsutveschlenktel Hafrangland Kompany Komansit Gesellschaft

Claims (5)

[Claims] (1) A matrix, a drawing core, surrounding the drawing core in an annular shape and supported so as to be movable in the axial direction, and when the matrix and the drawing core are relatively moved by a ram of a press, the matrix deep drawing a sheet metal part having a blank holder that engages with the blank holder; and reaction means that act on the blank holder and generate a reaction force in the blank holder when the blank holder is moved by the pressure of the matrix. A tool for the purpose of: said blank holder (22) and said drawing core (25) being provided with effective surfaces connected by a communication system containing an incompressible fluid (28) . (2) The blank holder (22) and the drawing core (25) are connected to a piston so that their effective surfaces cooperate by the communication system. Tools listed in. (3) The tool according to claim (1), wherein the blank holder (22) and the drawing core (25) are formed as a piston. (4) The annular blank holder (22) is connected to the cylinder (2
1), the drawing core (25) is slidably supported in the hole of the blank holder (22), and the cylinder (21) is sealed.
4. Tool according to claim 3, characterized in that the incompressible fluid (28) is filled in the incompressible fluid (28). (5) The communication system is connected to an incompressible fluid pressure source (29
) The tool according to any one of claims (1) to (4).