JP2010131625A - Method for forming flange-fitted cup product - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a new excellent forming method for obtaining a flange-fitted cup formed product in which a thickness difference between the flange part and the cup part is wide without causing defects such as cracks, and further, to provide a forming method and a forming device which can obtain a flange-fitted cup formed product from a sheet material or a rod material without causing defects by press forming comprising a preforming stage and a normal forming stage. <P>SOLUTION: The method for forming a flange-fitted cut product is characterized in that in the method where a stock having a boss and a flange is formed into a product having a flange, before a punch (3) is contacted with the stock (2), and forming is started, individual energizing forces (8a)(8b) are applied to both of the boss side of the flange (2b) and the boss-free side so as to hold the upper and lower faces of the flange material in the stock by dies (4) and (5), and forming is performed by the punch(3). <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a manufacturing technique for obtaining a molded product having a flange in a cup from a plate material or a bar material.

  Conventionally, molding of a product having a flange-like portion at the cup opening as shown in FIG. 1 has a large difference between the thickness of the flange (1a) and the thickness of the cup vertical wall (1c). Since it is difficult to form, such parts are often manufactured by cutting, but this cutting method has a low yield, manufacturing cost, etc., and requires a long time for manufacturing.

  On the other hand, production by a molding method has not been proposed. For example, Japanese Patent Application Laid-Open No. 2006-224112 of Patent Document 1 discloses that when a product having a flange-shaped portion is formed in a cup opening, a cup is formed at the lower end of the flange. There is described a press molding method including a volume movement (gathering) step for preventing tearing in advance of molding of a cylindrical shaped object for forming the cylindrical shaped object for forming. . In this press molding method, in order to compensate for the volume when a deep hole (cup) is formed in the flange-formed body, a sufficient amount of columnar protrusion (boss portion) is formed under the flange-formed body in advance to form a cup. It includes the meat gathering of such materials. In this molding process, a meat gathering process is provided in the first process, the punch tip descends beyond the flange portion in the second process, and a shape as shown in FIG. 1 is created in the third process. Although it is a process, since the volume of the boss part in the first process (gathering molding) only compensates for the volume shortage of the cup part molded in the second process, it is simply transferred. When press molding is performed with a mold having a shape, a tensile stress is generated at the joint (R) between the flange portion and the cup (However, in this Japanese Patent Laid-Open No. 2006-224112, the mold for molding and the like is used. Is not touched).

  For this reason, in order not to break by molding, the base portion (joint portion (R) with the flange) of the cup columnar projection (boss portion) for the cup needs a cross-sectional area that can withstand the tensile stress. In press molding, variations occur due to various factors. However, in the second molding process, variations occur in the bottom of the flange hole, and the flange hole bottom level is higher than the top of the cylindrical material projection (boss). When the punch tip does not descend to a sufficiently deep depth (ΔP in FIG. 3 of the same publication becomes smaller), the molding of the target flanged cup product in the third step (to achieve the shape of FIG. 4 of the same publication) ), A tensile force is applied to the base portion (a portion in FIG. 3 of the same publication) of the columnar projection (boss portion), and a molding defect such as a break or a crack occurs at this location, When ΔP increases, similar molding defects occur in the second step. In addition, when it is going to obtain the molded article of this invention as shown in FIG. 1 using the method of Unexamined-Japanese-Patent No. 2006-224112, the 3rd process description of this gazette is required, and more It is difficult to shorten the process.

JP 2006-224112 A

  Therefore, in view of the current state of the prior art, the object of the present invention is to obtain a flanged cup molded product having a large thickness difference between the flange portion and the cup, which is not easily affected by the shape before molding and is excellent in obtaining defects such as cracks. In addition, a flanged cup-molded product as shown in FIG. 1 can be obtained without defects by press molding comprising two steps of a pre-molding step and a main molding step from a plate or bar. An object of the present invention is to provide a molding method and a molding apparatus that can perform the above-described process.

The above problem is (1) in the method of molding a material having a boss and a flange into a product having a flange on a cup, before the punch comes into contact with the material and molding starts, the boss side of the flange, no boss A method for forming a flanged cup product, characterized in that an individual urging force is applied to both sides, the upper and lower surfaces of the flange material of the material are clamped by a mold, and then molded by punching. ";
(2) “The urging force from the bossless side of the flange applied to the mold holding the upper surface of the flange is greater than the urging force from the bossless side of the flange> the boss applied to the mold holding the lower surface of the flange. The forming method according to the item (1), which is the biasing force from the side ";
(3) The item (1) or (2), wherein the material can be preformed in a state where the tip position where the punch descends at the time of molding does not reach the base position on the flange side of the boss. The forming method according to claim 1;
(4) The items (1) to (1), wherein the boss portion can be molded regardless of whether the tip position where the punch descends during molding exceeds the boss root position or the boss root position. The problem is solved by the molding method according to any one of items 3).

  As will be apparent from the following detailed and specific description, by using the mold structure as in the molding method of the present invention, molding to obtain a flanged cup product is performed in a stress field mainly composed of compressive stress. It is possible to obtain a molded product having a large thickness difference between the cup and the cup without defects such as cracks. Moreover, the extremely excellent effect that a molded product as shown in FIG. 1 can be obtained from a plate material or a bar material by preliminary molding and molding in two steps of the molding method of the present invention is exhibited.

In the present invention, a novel molding method is devised that is particularly suitable for integrally molding a product having a flange on a cup from a material having a boss and a flange portion without being restricted in shape. Hereinafter, this molding method will be described in detail with reference to the drawings.
FIG. 1 shows an example of a product according to the present invention, and FIG. 2 shows an example of a material used when molding such a product. Here, the product (1) example of FIG. 1 has a thick flange (1a) -like portion at the opening of the hole (1g) of the cup (1b) having the thin cup vertical wall (1c). Moreover, the raw material (2) example shown by FIG. 2 has a recessed part (2f) in the surface of a flange part (2b), and a boss | hub part (2a) in a back surface. A boss | hub part (2a) and a recessed part (2f) can be formed by preforming a disk-shaped raw material or a cylindrical raw material, for example.

3 to 5 show a schematic configuration of an example of a molding apparatus suitable for carrying out the molding method of the present invention and the main points of a molding sequence of the present invention using this apparatus.
(A). In the molding apparatus of this example, the cushion pad (4) disposed in the cavity of the punch holder (3b) precedes the lowering of the punch (3) for forming the cup (1) from the material (2). ) Descends and comes into contact with the upper surface (2c) of the flange portion (2b) of the material (2). Thus, the material (2) is sandwiched between the cushion pad (4) and the die (5). In this example, the cushion pad (4) is supported by a spring (8a) and a slider so as to be movable up and down. The punch (3) can slide up and down the hole of the cushion pad (4), and the die (5) is held movably up and down by the spring (8b) on the die holder (7) on the bolster. (6) is arranged so that the hole of the die (5) can be moved up and down (FIG. 3).

  (B). When the cushion pad (4) comes into contact with the upper surface (2c) of the flange portion (2b) of the material (2), the upper cushion force (the urging force from the flange-free side)> the lower cushion force (holds the flange lower surface). Since it is a condition of the urging force from the boss side applied to the mold, the material (2) and the die (5) are pushed down simultaneously. For this reason, the flange portion (2b) is sandwiched between the cushion pad (4) and the die (5) and is in a state where a compressive force is applied.

  (C). Next, the tip (2d) of the boss part (2a) comes into contact with the lower counter punch (6) (FIG. 4), and then only the punch (3) descends along with the slide of the press. ) And the molding of the cup is started.

  (D) Thereafter, as the punch (3) proceeds, the material flows upward, but the flow is controlled by the cushion pad (4). Further, when the material flows upward, the die (5) also moves upward as the material flows. Thereby, the molded cup vertical wall (1c) does not cause molding defects such as buckling due to the force of the cushion pad (4).

(E) When the punch (3) passes through the flange portion (2b), the cushion portion (4) is provided on the connecting portion R (1d) of the flange portion (2b) and the boss portion (2a) that are most likely to break. Since the cushioning force acting on the die (5) is larger than the cushioning force acting on the die (5) (about 0.02% to 24%), a compression force is applied. For this reason, the joint R portion (1d) can pass through the flange portion (2b) without causing breakage due to the tensile force.

  (F) After the punch tip (3a) has passed through the flange portion (2b), it becomes a steady region of backward extrusion with back pressure applied, so that no tensile stress is generated in the connecting R portion (1d). Since the die (5) is always in contact with the molded product, the molding proceeds without buckling of the cup vertical wall (1c) due to the cushioning force of the cushion pad (4), and at the bottom dead center of the press. Molding ends. In this molding method, since the thickness (1f) of the cup bottom is determined at the press bottom dead center, the variation in the thickness (1f) of the cup bottom is small. For this reason, the variation of the material which flows is also reduced. Moreover, there is no fluctuation | variation of the cushion force to be used. Alternatively, if the variation is constant, the variation in the total length due to the cushioning force is reduced. That is, in the molding method of the present invention, since the variation in the thickness (1f) of the cup bottom is small, the variation in the total length of the molded product is also small.

  That is, in the present invention, by giving individual urging forces to both the boss side of the flange and the side without the boss before molding is started and sandwiching the upper and lower surfaces of the flange material of the material with a mold, It is possible to obtain a molded product with a large thickness difference between the flange part and the cup without causing a tensile stress on the joint part between the flange part and the bottomed cup hollow boss part and without generating defects such as cracks at the joint part. it can.

  The cushion pad (4) is configured such that the urging force from the bossless side (upward direction) of the flange is greater than the urging force from the boss side (downward direction) applied to the mold that holds the lower surface of the flange. Since the cushioning force acting on the die (5) is larger than the cushioning force acting on the die (5), a compressive force is applied. Therefore, the joint R portion (1d) does not break due to the tensile force, and the punch tip (3a) has the flange portion. (2b) can be passed.

  In addition, as a pre-process of the molding method described in (1) above, a flange part and a cup can be formed by molding a total of two steps from a plate or a bar by adding a pre-form that creates a shape suitable for the product to be obtained. A molded product having a large difference in thickness can be obtained.

  Furthermore, the boss portion can be formed in any case where the tip position where the punch descends at the time of molding exceeds the boss root position or the boss root position. This point will be described below. It is characterized in that an urging force is applied to both the boss side and the non-boss side, and molding is performed by punching. The position of the tensile stress applied to the boss root R portion changes with the punch tip position (molding end position) at the boss root position. In the molding method of the present invention, molding can be performed at any position where the tip of the punch is located.

  As a method for obtaining the cushioning force necessary for performing the above molding method, it is sufficient that the cushion pad (4) is subjected to a normal pressure force. Therefore, a method using hydraulic pressure or pneumatic pressure, a gas, a spring, or the like. There is a method to obtain a cushioning force by the die, and the die (5) needs to follow the behavior of the work material so that it does not leave the work material during molding, so an accumulator using hydraulic pressure, pneumatic pressure, etc. Alternatively, a method using a spring, a gas cushion or the like can be used. In addition, when this molding method is molded under the condition of “upper cushion force <lower cushion force”, when the punch passes through the flange part (2b), a tensile force due to the lower cushion force is generated at the joint R part (1d). Then, cracks occurred in the connecting R portion (1d). If this was the condition of “upper cushioning force = lower cushioning force”, molding was possible without defects such as cracks. Similarly, molding was possible without defects even under the condition of “upper cushioning force> lower cushioning force”. For this reason, in the molding method of the present invention, it is necessary to satisfy the condition “upper cushion force ≧ lower cushion force”. However, in order to stably perform molding, it is desirable to mold under the condition of “upper cushioning force> lower cushioning force” in consideration of various molding variations (cushioning force and the like). In this case, it is not essential to increase the urging force on the bossless side as the punch is lowered, but it is preferable.

Further, as an example of a material used in the present forming method, a plate material or a bar material is preformed by a press or a former (horizontal press) or the like, and is formed into a shape as shown in FIG. Here, this FIG. 2 is “in order to avoid breaking when the punch passes through the flange portion in the post-process molding” as described in the direction of the above-mentioned JP-A-2006-224112. Instead, it is a shape for volume distribution of the flange portion (1a) and the cup (1b) of the molded product, which is different from the prevention of breakage caused by the subsequent molding. Further, the recess (2f) in the center of the upper surface of the flange is provided for reducing the material to be flowed by the punch in the molding of the present invention and for guiding the punch. If there is little material to be used, it can be made unnecessary. For the reasons described above, the dimensions of the material shown in FIG. 2 such as the flange, the boss, and the hole at the center of the flange end face need to be changed depending on the dimensions of the molded product to be obtained. Thus, the product example shown in FIG. 1 can be obtained by two-step molding of “preliminary molding” and “main molding method”.
Finally, the method for carrying out this molding may be carried out in a single step or may be produced by being incorporated into a multi-step molding. The cushion device can be placed in a mold, a die set, or a press, and the placement method may be determined as necessary.

It is the example of a product shape | molded using the shaping | molding method of this invention. It is a raw material example used when shape | molding the said product example. It is an example explaining the shaping | molding start time in the shaping | molding method of this invention. It is an example explaining the middle of the shaping | molding in the shaping | molding method of this invention. It is an example explaining the time of completion | finish of shaping | molding in the shaping | molding method of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Molded product which has a flange in a cup 1a Flange 1b Cup 1c Cup vertical wall 1d Connection R part 1f Thickness 1g of cup bottom part Hole 2 Material 2a Boss part 2b Flange part 2c Upper surface 2e of flange part 2d Bottom end of boss part 2f Concavity 3 Punch 3a Punch tip 3b Punch holder 4 Cushion pad 5 Die 6 Lower counter punch 7 Die holder 8a Spring 8b Spring

Claims (4)

  In the method of forming a material with a boss and flange into a product with a flange on the cup, separate urging forces are applied to both the boss side and the non-boss side of the flange before the punch comes into contact with the material and molding starts. A method of forming a flanged cup product, wherein the upper and lower surfaces of the flange material of the material are sandwiched between molds and molded by punching.   The urging force from the bossless side of the flange applied to the mold holding the upper surface of the flange is greater than the urging force from the bossless side of the flange> the boss side applied to the mold holding the lower surface of the flange. The molding method according to claim 1, wherein the molding method is an urging force.   3. The molding method according to claim 1, wherein the material can be preformed in a state where a tip position where the punch descends does not reach a base position on the flange side of the boss during molding.   4. The boss portion can be formed in any case where the tip position where the punch descends during molding exceeds the boss root position or the boss root position. Molding method.

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