JP2852143B2 - Mold for forming ribbed members - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a precision die forging method for a metal material, and more particularly to a die for forming a ribbed member having a rib having a relatively high height.

[0002]

2. Description of the Related Art In recent years, with the development of precision die forging technology, members having ribs, webs, and the like, which are high in height and difficult to form, are also being die forged into a Nine net shape.
On the other hand, when forging these ribbed members by die forging, as shown in FIG.
The material of the main part (22a) of the rib part (22b) of the mold (2) is
From the point when the impression of 1) is almost full, the main part
The material applied to the ribs (22b)
Is formed by a kind of backward extrusion that is filled into the impression of the mold (21) corresponding to the above.

[0003] For this reason, the rib portion during molding becomes a free surface to which the pressing force does not reach, and is affected by the pressing force applied to the material at the base end thereof and the frictional resistance with the mold surface.
Each part deforms at a different molding speed, extends the height irrespective of the expected height shape, the tip reaches the predetermined impression surface unevenly, the material of the part that arrived first, It flows sideways to form overburden and wrinkles, or causes large deformation resistance to cause underfill in a delayed part.

[0004] This problem becomes more remarkable as the rib of the target member has an intersection or a corner or has a complicated shape with a large variation in height. Since good products cannot be obtained, conventionally, for example,
As shown in FIG. 3 which is an explanatory view of the molding method, first, an intermediate molded product (32) in which a rib portion (32a) is formed freely from a wasteland (31) is die-forged, and then the intermediate molded product is formed. The end of the rib (32a) of the product (32) is machined into a shape considering the final shape to obtain a finished wasteland (33).
A method of die forging a ribbed member (34) for the purpose of (33) has been adopted.

[0005]

However, in the above-mentioned conventional molding method, although a member having a high height and complicated ribs and webs can be molded into a near net shape, at least two sets of gold are used for the molding. There is a problem that a mold is required, the material yield is reduced due to intermediate machining, the cost is increased, and the number of steps is large and productivity is poor.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems of the prior art, and it is possible to uniformly control the forming speed of a rib portion during pressure forming, and to obtain a rib portion having a high height and a complicated shape. It is another object of the present invention to provide a rib- formed member that can be accurately formed by one-step die forging.

[0007]

In order to achieve the above object, the present invention has the following arrangement. That is, the book
The mold for forming a ribbed member according to the present invention comprises a ribbed member.
In the upper and lower molds with shaping impression,
At the part corresponding to the rib part of the above mold, the cross section of the rib part
A through hole with the same shape as the
The back pressure plate is inserted into the through hole so that it can move up and down.
On the mold, a supplementary device with a built-in pressure means for applying back pressure to the back pressure plate
It is characterized by attaching a sub die.

[0008]

[0009]

In the mold of the present invention, a portion corresponding to the rib portion of the upper mold is provided.
The through hole with the same shape as the cross section of the rib
And the back pressure plate can be moved up and down in the through hole.
On the other hand, back pressure is applied to the back pressure plate on this upper mold.
Since an auxiliary mold with an internal pressurizing means is attached,
Via the back pressure plate, on the rib portion of the member being pressed
A predetermined back pressure can be applied to the end face.

Then, during the pressure forming through the back pressure plate,
A predetermined back pressure is applied to the upper end surface of the rib portion of the member to be molded.
The ribs to be formed
The shape speed can be controlled uniformly. In addition, pressure molding
The back pressure applied to the end face of the rib portion of the member to be molded is
The elastic limit of the material of the molded member under the molding temperature condition
The molding speed of the rib to be molded with the same strength of pressure
It is effective to control the degree.

[0011]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a cross-sectional view showing a mold for forming a member with ribs according to one embodiment of the present invention. FIG. 1A shows an initial stage of forming a member to be formed under pressure, and FIG. The figure is a cross-sectional view showing a state at each stage of completion of molding.

In FIG. 1, (1) is a lower mold, and this lower mold (1) is provided with an impression (1a) for molding a main portion MB of a member M to be molded. .

(2) is an upper mold, and the upper mold (2)
Is formed in a portion corresponding to the rib portion MR of the member M to be formed in the vertical direction with a through hole (2a) having the same shape as the cross-sectional shape of the rib portion MR and having a lower portion forming an impression for forming the rib portion MR. It is provided to penetrate.

(3) is a back pressure plate, and this back pressure plate (3)
Is formed with a flat upper end surface and a lower end surface having a shape corresponding to the shape of the upper end surface of the rib portion MR of the molded member M, and is formed in the through hole (2a) of the upper mold (2). Movably fitted in the vertical direction.

(4) is an auxiliary mold, and this auxiliary mold is
(4) is a flat plate having a shape approximately the same as that of the upper mold (2),
It is detachably mounted on the upper mold (2). Also,
In the auxiliary mold (4), cylinders (5) are vertically provided at two positions located on the through holes (2a) of the upper mold (2). The output shafts (5a) of the cylinders (5) are connected to the upper end of a back pressure plate (3) fitted into the through hole (2a) of the upper mold (2).

(6) is a hydraulic device.
(6) is a portable type that is connected to the cylinder (5) via the flexible pipe (7). When a reaction force is applied to the cylinder (5), the back that moves backward under the set pressure is used. It has a pressure control mechanism.

Next, the pressure forming of the ribbed member by the mold of the present embodiment having the above configuration will be described.

First, the back pressure plate (3) is lowered from the reference position to the initial setting position by the cylinder (5), and then, as in a conventional method, a forging device (not shown) is used for the upper die. (2) is pressed down to press the member to be molded M placed on the lower mold (1). Here, the reference position of the back pressure plate (3) is such a height position that the upper end surface is in contact with the lower surface of the auxiliary mold (4) and the lower end surface is the same as the upper end surface of the rib portion MR of the member M to be molded. In addition, the initial setting position is a height position where the lowermost end surface is substantially the same height as the lower end of the through hole (2a) of the upper mold (2).

On the other hand, the member to be molded M pressed under the pressure of the upper mold (2) fills the impression (1a) of the lower mold (1) as shown in FIG. While the main part MB is being formed, a part of the material is pushed into the through hole (2a) of the upper mold (2) so as not to rise. However, the lower part of the through hole (2a) forms an impression forming the rib part MR.
Inside, the back pressure plate (3) is lowered from the reference position and waiting, so that the material pushed into this through hole (2a) is prevented from rising uncontrollably, and first the back pressure plate (3) ) Is filled with a portion having a high lower end surface and a low resistance (for example, a portion corresponding to portion (a) in FIG. 3 (a)) and abuts over the entire lower end surface of the back pressure plate (3). ) Is pushed upward.

By the way, a metal material undergoes plastic deformation when a stress exceeding its elastic limit is applied. In general, when a metal material is formed by a die forging method or the like, the metal material greatly exceeds the elastic limit of the metal material. Apply pressure stress to plastically deform to the desired shape. Therefore, in order to uniformly control the forming speed in each cross section of the rib portion MR by the resistance of the back pressure plate (3) while forming the rib portion MR by pressing down the lower mold (1), the forming temperature condition is required. The most effective and stable result can be obtained by applying a back pressure to the back pressure plate (3) having substantially the same strength as the elastic limit of the material of the member M below. Therefore, in this embodiment, the elastic limit of the material of the member M under the molding temperature condition is examined in advance, and a back pressure slightly higher than the elastic limit is applied to the back pressure plate (3). Then, the set back pressure for the cylinder (5) of the hydraulic device (6) was adjusted.

Subsequently, when the upper mold (2) is lowered, the back pressure plate (3) is pushed back to the reference position as shown in FIG.
The upper end surface contacts the lower surface of the auxiliary mold (4) and stops.
On the other hand, the material pressed into the through hole (2a) of the upper mold (2) and formed into the rib portion MR has a uniform forming speed in each cross section due to the resistance required for pushing back the back pressure plate (3). While being controlled to a final shape.

The member to be molded M molded as described above
In the initial stage, the shape of the upper end face is regulated, and the ribs MR are molded while controlling the molding speed evenly in each cross section. It is formed with high precision in one step without causing scratches and lack of thickness.

[0023]

As described above, according to the mold for forming a ribbed member according to the present invention, the forming speed of the rib portion during the pressure forming can be controlled uniformly, and the height can be increased. Even a ribbed member having a rib with a complicated shape can be formed with high precision and efficiency by one-step die forging, and the productivity can be remarkably improved.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view showing a mold for forming a member with ribs according to an embodiment of the present invention. FIG. 1 (a) is an initial stage of molding when a member to be molded is subjected to pressure molding, and FIG. FIG. 4 is a cross-sectional view showing a state at each of the molding end stages.

FIG. 2 is a conceptual explanatory view of die forging of a member with ribs.

FIG. 3 is an explanatory view of a conventional method for forming a ribbed member.

[Explanation of symbols]

(1)-Lower mold (1a)-Impression (2)-Upper mold (2a)-Through hole (3)-Back pressure plate (4)-Auxiliary mold (5)-Cylinder (5a)-Output shaft (6)-Hydraulic device (7)-Flexible pipe M-Molded member MB-Main part MR-Rib

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-55-14159 (JP, A) (58) Fields investigated (Int. Cl. ⁶ , DB name) B21J 1/00-13/14 B21J 17 / 00-19/04 B21K 1/00-31/00

Claims (1)

(57) [Claims] 1. An upper and lower mold provided with an impression for molding a ribbed member, and a through hole having the same cross-sectional shape as the cross section of the rib is provided in a portion corresponding to the rib of the upper mold in the vertical direction. In addition, the back pressure plate is vertically movably fitted into the through hole, and an auxiliary mold having a pressurizing means for applying a back pressure to the back pressure plate is mounted on the upper mold. For forming a ribbed member.