KR100907683B1 - Press forming apparatus of metal sheet using a movable binder - Google Patents

Abstract

The present invention provides a press molding apparatus specially devised in order to improve workability during metal plate press forming. In press molding, when the metal sheet is introduced into the die, the upper and lower binders, which are formed independently of the die and can move in a specific direction, are introduced together with the metal sheet in a horizontal direction with an appropriate resistance force, so that the optimum tensile force is applied to the metal sheet being processed. It prevents the thickness reduction rate of the metal plate from being concentrated on a specific part, and evenly distributes the strain rate throughout the deformation area, thereby enabling processing of deep and complicated parts.

Moving binder, binder flow rate control, press molding

Description

Press shaping device for shaping metal sheet using movable-type binder}

The present invention relates to a press forming apparatus using a movable-type binder (movable-type binder) specially devised to improve workability during press forming processing of a metal sheet.

In general, during press molding, when the metal sheet is introduced into the die, the upper and lower binders, which are formed independently of the die and can move in a specific direction, are introduced together with the metal sheet in a horizontal direction with an appropriate resistance force, so that they are optimal for the metal sheet being processed. It should be able to give the tensile force of, reduce the thickness reduction rate of metal plate to be concentrated in the specific area, and evenly distribute the strain rate throughout the deformation area to enable the processing of deep and complex parts.

However, when press molding of a metal sheet, as the molding depth is deepened, deformation is concentrated on the bent portion, the shape abrupt portion, the side wall portion, and the like, thereby causing a molding defect. It is an invention that enables the manufacture of even parts of complex shape including a large number of shape sudden parts.

In the case of press molding processing, structural member for automobile body and reinforcement for collision safety have deep processing depth and complicated shape, which causes many problems such as breakage and wrinkles during press molding. Decrease productivity.

 Conventional press molding dies are generally composed of an upper mold, a lower binder called a binder, and a punch, in which an upper binder and a die are integrally attached. Accordingly, during molding, the metal sheet material is processed into a specific shape while being introduced into the die along the stroke of the punch while being caught by a constant force between the die and the lower binder. At this time, draw beads may be added to the binder surface to control the inflow of the metal sheet. However, when the inflow of the metal sheet is suppressed by the addition of draw beads, the tension applied to the sheet during processing is increased as much as it is suppressed.

 However, in this press working method, since the binding area decreases as the inflow rate of the metal sheet into the die increases, the binding pressure per unit area of the binding portion of the metal sheet increases. When press-molding in this way, most of the tensile force applied to the metal sheet being processed as the punch stroke increases is due to the restraint from the binder and despite the fact that the binding area, that is, the area of the restraint portion gradually decreases with the inflow of the sheet, Due to the increased binding pressure, the tensile force remains constant without significant change.

Alternatively, the same result is obtained when the size of the metal sheet has a sufficiently large margin so that the binding area is kept constant. If the tensile force is constantly maintained on the metal sheet being processed, it is difficult to control the nonuniformity of the thickness reduction rate of the metal sheet due to the processing, thereby increasing the probability of breakage in the shape change portion, the protrusion and the side wall portion.

Recent trends include general soft steel plates, as automakers are in a position to increase the adoption of high-strength steel in body parts in order to solve environmental problems caused by air pollution and energy saving and to ensure passenger safety due to collisions. As a result, it is actively replacing the nominal tensile strength of 340 ~ 440MPa grade high strength steel plate with 590 ~ 1180MPa grade high tensile strength steel, but this is causing additional molding defects. In order to satisfy the thickness reduction and vehicle weight reduction of the steel sheet by increasing the strength of the steel sheet for automobiles, it is necessary to introduce an appropriate molding technology. However, since most of the molding methods follow the conventional press molding method, the problem of poor molding due to the high strength is increased. It increases the time and cost for test production and mass production.

Conventional methods that have emerged to solve these problems include press molding method using variable binding pressure, two-stage press molding method, draw molding method using over-run punch, recently developed by JFE Steel of Japan. Various molding methods have been developed, such as the JIM-Form method.

However, these methods have a lot of restrictions in their use due to the complexity of the process procedure so that the configuration of the device is excessively complex and easy to cause mold defects.

The present invention, through the introduction of a mobile binder independently configured as a result of the study, confirms that the press-molding apparatus and the press-molding method using the same can solve the above problems even when using a high-strength steel sheet The present invention has been reached.

The present invention takes into consideration the strength and thickness of the metal sheet and the shape of the part to be molded, and by lowering the difference in the stress distribution remaining on the plate through the introduction of a mobile binder that can appropriately control the tensile force applied to the metal sheet after finishing The purpose of the present invention is to reduce the problem of poor shape freezing caused by elastic restoration and to suppress the breakage caused by local concentration of strain during deformation, thereby improving the press formability of the metal sheet.

In order to achieve the above object, the present invention provides a metal sheet die to prevent and disperse the deformation concentrated in the bent portion, shape abrupt portion, side wall portion, etc. according to the depth of the forming depth or complex shape during press molding processing of the metal sheet The upper binder and the lower binder, which are horizontally movable movable binders configured independently of the die when they are introduced into the inside of the die, are constituted, and when the binder is moved horizontally with an appropriate resistance force together with the metal sheet, the binder holding force is adjusted and the material. By adjusting the flow rate, it is possible to impart an optimal tensile force to the metal sheet being processed, thereby preventing the thickness reduction rate of the metal sheet from being concentrated on a specific site and evenly dispersing the strain rate throughout the deformation region. Binder connector, binder holding force adjustment spring, It is composed of press press forming device based on material inflow control spring, damper and load cell for tensile force measurement.

According to the effect of the present invention, by the sensitive and fine control of the tensile force applied to the material can effectively prevent the breakage caused by the overload of the tensile force during molding and increase the tensile force as safely as possible in the range of the fracture does not occur Therefore, the stress distribution can be effectively uniformed, and excellent shape freezing can be obtained. In addition, the load cell 10 connected to the movable binder can be measured in real time the exact tensile force applied to the material during processing, it is possible to perform a safer and more precise work by securing data through repeated tests for each material thickness .

Hereinafter, with reference to the accompanying drawings, the configuration and operation for achieving the object of the present invention will be described in detail.

1 shows a configuration of a press forming apparatus using a movable binder according to the present invention.

The press molding apparatus according to the present invention is a die (1), upper binder (2), lower binder (3), punch (4), binder connector (6), binder holding force adjustment spring (7), binder inflow rate adjustment spring (8) ), A rolling bearing 9 for binder movement, a load cell 10 for tensile force measurement, and a damper 11 for alleviating sudden movement of the spring 8 for adjusting the binder inflow amount.

When the metal sheet P is introduced into the die in order to prevent and disperse the deformation in the bending part, the sharp edge portion, the side wall part, etc. according to the depth of the molding or the complicated shape during the press molding processing of the metal sheet. The upper binder 2 and the lower binder 3, which are configured independently of the die and can move in the horizontal direction, are respectively installed on the left and right sides of the pair of die dies 1, and these binders 2 and 3 are made of metal sheet P. In addition, it moves in the horizontal direction (x-axis) with proper resistance to give optimum tensile force to the metal sheet being processed, prevents the thickness reduction rate of the metal sheet from concentrating on a specific part, and distributes the strain evenly throughout the deformation area. A spring in which a binder connector 6 is connected to the upper and lower binders 2 and 3, and a binder inflow rate regulating spring 8 further connected to the binder connector 6 is settled. A damper (11) capable of reciprocating concentrically on the surface of the biaxial shaft (12) and the spring hook shaft (12), and the load cell (10) for measuring the tension force on both sides of the damper (11) is also referred to as the lower binder (3). A spring 7 for adjusting the binder holding force, which is compressible and recoverable on the y axis, is also provided below.

The movable upper and lower binders 2 and 3 are connected by a binder connector 6 to a spring 7 for adjusting or holding the binder holding force, which is compressible or reversible, as shown in the thick arrow (y-axis direction) of FIG. 2. Whenever the punch 4 moves into the space part 5 of (1), the inflow amount of the metal material which flows into a die can be adjusted arbitrarily.

1 and 2, the upper and lower binders 2 and 3 have a spring hanger shaft 12 and a damper in which the binder inflow rate adjusting spring 8 is placed by the binder connector 6; 11) is structured so that it can be operated and connected. In addition, the load cell 10 for tensile force measurement is connected to both ends of the damper 11.

As shown in FIGS. 1 and 2, when the punch 4 is operated by a predetermined stroke along the y-axis to the empty space 5 of the mold die 1 (FIG. 2), a metal material flowing between the left and right movable binders ( P) is drawn as shown in Figure 2 while pulling the left and right end metal material toward the center to move the movable binder (2) (3) to the center on the horizontal axis (x-axis). At this time, the reaction force against the tensile force of the metal material (P) is acted on the spring for adjusting the binder inflow rate to achieve an equilibrium at a certain point. That is, a binder holding force adjustment spring in which a metal material completely constrained to the horizontal (x) axis movable upper binder (2) and the lower binder (3) is coupled to the horizontal movable binder (2) (3) through the binder connector (6). (8) and the damper (11) by allowing the metal material to be introduced into the die while balancing the force with the combination is to be able to arbitrarily control the inflow of the metal material.

In the conventional press-forming apparatus, the upper binder is integrally formed with the die, but a feature of the present invention is that the metal material is completely restrained by the upper binder 2 and the lower binder 3 that can move on the horizontal (x) axis. Is connected to the binder holding force adjustment spring 7 coupled to the horizontally movable binders 2 and 3 by means of the binder connector 6 so that the metal sheet P during the press working is formed with the inner space 5 of the die 1. When introduced into, it is characterized in that the amount of metal plate or metal (material) (P) can be arbitrarily adjusted.

When the processing depth of press molding is constant, when the inflow of material is large, the tensile force applied to the material being processed decreases, so that the occurrence of breakage in the shape change part or side wall part is reduced, but the shape freezing after processing decreases, and the inflow of material In a small case, the tensile force applied to the material being processed increases, so that the incidence of breakage increases, while shape freezing after processing has a good relationship. Because of this relationship, proper inflow of material is an important factor to satisfy both formability and shape freezing simultaneously.

In the conventional press molding process, the binder holding force is adjusted to appropriately control the flow rate of the material. In general, the binder holding force is kept constant during the process, and in some cases a variable binder holding force is applied during the process. At this time, since the binder holding force acts as a perpendicular force to the holding area of the material, the tensile force applied in the material direction is proportional to the friction coefficient and the vertical force between the material and the binder. However, in the case of press molding by this method, it is difficult to apply uniform distribution of binder holding force due to the change of contact conditions with the binder depending on the state of the surface of the material, so that it is difficult to precisely control the inflow of the material during processing. It has a drawback that it is impossible to control the tensile force strictly.

The device according to the present invention proposed to remedy this drawback is based on a movable binder such as the upper binder 2 and the lower binder 3 which can move in the horizontal direction, as described above, and the binder connector 6, The binder holding force adjustment spring (7), the binder inflow rate adjustment spring (8) and the damper (11) combination and the balance of the force by the tension force to be introduced into the die to allow the arbitrary adjustment of the inflow of the metal material, In addition to the above components to provide a press forming apparatus consisting of a load cell 10 for measuring the tensile force as a basic element, the method and the configuration and operation of each device according to the present invention is as follows.

As shown in FIG. 1, the metal sheet P is sandwiched between the upper binder 2 and the lower binder 3. When the binder P is sufficiently large and the plate P is completely constrained to the binder, the horizontal movement amount of the upper binder 2 and the lower binder 3 is proportional to, or coincidence with, the inflow of the material, so that the operator has to Determine the appropriate binder holding force by considering the thickness and type of material and the shape of the part to be machined. At this time, the adjustment of the material inflow amount is determined according to the type and number of the spring (8) for adjusting the binder inflow amount.

The binder holding force BF is applied to the lower binder 3 until the material is sufficiently constrained to the binder. Next, it appears by compression of the binder holding force adjustment spring 7 shown in FIG.

When press forming begins and the punch is moved to the die 1 along the y axis (center of FIG. 2) toward the metal material (or plate), the material P flows into the die 1 and the upper binder 2 And the lower binder 3 tries to move in the direction of a small arrow on the x-axis, that is, in the center direction as the material P is introduced. At this time, the reaction force by the action of the springs 8 and 11 acts on the upper and lower binders, and the upper and lower binders 2 and 3 are applied to the material P, and the tension T ₁ (T ₂ ) is applied. ) And the horizontal movement of the force in every moment, so that the tension applied to the material (P) during machining can be accurately measured through the load cell.

When the punch 4 reaches the top dead center with a certain stroke, the molding is finished, the punch 4 is released and the binder holding force is removed to end the process of removing the finished part from the mold such as the die 1. This completes all the processes of the present invention.

1 is a schematic diagram of a press forming system according to the present invention

Figure 2: Press molding process diagram of the present invention

<Key sign>

1. die 2. upper binder

3. Lower binder 4. Punch

5. Sheet metal 6. Binder connector

7. Spring for adjusting binder holding force 8. Spring for adjusting binder inflow

9. Rolling Bearings 10. Load Cells 11. Dampers

12. Spring hanger shaft

Claims (4)

When the metal sheet P is introduced into the die in order to prevent and disperse the deformation in the bending part, the sharp edge portion, the side wall part, etc. according to the depth of the molding or the complicated shape during the press molding processing of the metal sheet. The upper binder 2 and the lower binder 3, which are configured independently of the die and move in the horizontal direction, are installed on the left and right sides of the pair of mold dies 1, respectively, to give an optimum tensile force to the metal sheet P being processed. And the binder (2) (3) is installed to flow in the horizontal direction together with the metal plate material with a resistance to prevent the thickness reduction rate of the metal plate material from being concentrated at a specific site and to evenly distribute the strain rate throughout the deformation region. A binder connector 6 is connected to the upper and lower binders 2 and 3, and a spring hanger shaft 12 and a spring in which a binder inflow rate regulating spring 8, which is connected to this binder connector 6, is placed. A damper (11) capable of reciprocating concentrically on the surface of the spring holder shaft (12) is mounted, and compresses the load cell (10) for measuring the tensile force in the y axis under the lower binder (3) outwardly of the damper (11). ㆍ A press forming apparatus for a metal plate using a movable binder, characterized in that a spring 7 for adjusting a binder holding force is installed. The movable upper and lower binders (2) and (3) of claim 1, which are connected to the binder holding force adjustment springs (7) by the binder connector (6) to punch into the space (5) of the die (1). Press forming apparatus for a metal sheet using a movable binder, characterized in that the amount of the metal material flowing into the die can be arbitrarily adjusted when (4) moves. delete delete

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