CN111889531A - A kind of curved generatrix shell front and back extrusion forming die and forming method - Google Patents

Abstract

The invention discloses a forward and reverse extrusion forming die and a forming method for a curved generatrix shell. The blank is mainly in the forward flow, and the positive extrusion forming space is preferentially filled to promote the forward flow of the material and increase the strain amount of the dead zone material; when the extrusion punch continues to move downward, after the positive extrusion forming space is filled , the blank at the lower end of the extrusion punch mainly flows in the reverse direction and fills the forming cavity. An overflow groove is set on the upper part of the reverse extrusion forming cavity, the extrusion punch is pressed down into the overflow groove, the billet is closed and extruded in the forming cavity, and the billet flows forward and reverse at the same time, which promotes the forward direction of the mouth material. flow, increase the strain amount of the material in the rigid translation zone, so as to achieve uniform material strain in different parts of the shell, and solve the problems of uneven deformation and large differences in mechanical properties between different parts and different directions after the existing curved generatrix shell is formed. .

Description

A kind of curved generatrix shell front and back extrusion forming die and forming method

technical field

The invention belongs to the technical field of forming and processing, and in particular relates to a forward and reverse extrusion forming die of a curved generatrix type shell and a forming method.

Background technique

Extrusion forming is a forging forming process. The blank is subjected to three-way compressive stress and has uniform circumferential mechanical properties, which is suitable for forming difficult-to-deform metal materials. During the extrusion process, the blank and the die move relative to each other, and the material flows out in the same direction as the extrusion axis, which is called positive extrusion;

It is recorded in the patent with the application number CN201710544672.2 that when the grid changes in each stage of traditional positive extrusion, the grid changes inside the billet are divided into three areas: the I area is the metal dead area, which is close to the end face of the punch, Conical. The size of the taper is determined by the amount of friction between the punch end face and the blank. This part of the metal is basically not deformed. Zone II is the severe deformation zone. The billet flows sharply outward and upward in this area, and the cup-shaped part is mainly formed by this part of the metal flow. The axial height of this area is about 0.1d to 0.2d (d is the diameter of the working part of the punch). When the punch is pressed down to the height of the bottom of the billet is still greater than the axial height, although the metal in the deformation zone produces a violent flow, a part of the metal at the bottom still remains in its original shape, and it is still in a stable deformation state, but when the punch continues Press down, when the residual thickness of the blank is less than the height of the axial direction, all the metal in the residual thickness will flow and become an unstable deformation state. Zone III is a rigid translation zone. After the metal flow in the violent deformation zone forms the cup wall, it will no longer deform, but move upward in the form of rigid body translation. This movement continues until the punch stops pressing down. When the bottom thickness of the dead zone is too thin, the material with poor plasticity will produce annular shedding.

The blank and the die do not move relative to each other, and the material flows out in the opposite direction of the extrusion axis, which is called reverse extrusion. During the reverse extrusion forming process, the material temperature rise is small, and the forming temperature is easy to control.

In the patent with the application number of CN201610681623.9, a method and a mold for forming fine grains by reverse extrusion of an elongated member rotating die are disclosed, including an upper die structure and a lower die structure. Then, under the action of the active die, the punch moves relatively in the axial direction to cause the blank to plastically deform; when the working belt area of the punch completely enters the interior of the billet, the punch moves relatively along the axial direction, and simultaneously extrudes along the central axis of the extrusion. Rotational movement, when the left and right inserts are in contact with the height-limiting block, the left and right inserts slide relative to each other in the punch at the same time, causing the billet to undergo continuous rotational extrusion and fine-grain deformation. It can greatly reduce the forming load, enhance the stability of the punch, and improve the aspect ratio of the punch. Long member manufacturing performance.

In the patent with the patent number of CN201811422161.4, a multi-punch step-by-step reverse extrusion forming method is disclosed, using a multi-punch composed of an inner punch and an outer punch, including: blanking - blanking - Step-by-step reverse extrusion - Subsequent processing, characterized in that: the step-by-step reverse extrusion is to use an inner punch and an outer punch to extrude the billet metal at least once, and the billet metal is placed in the multiple punches. Flow deformation is generated under the action of , and by controlling the stroke of the inner punch and the outer punch, a hollow part with a solid flat bottom, a concave bottom, or a convex bottom is obtained. The invention can realize the forming and manufacturing of hollow parts such as flat bottom, convex bottom and concave bottom in the same set of molds; the reduction of the extrusion forming contact area reduces the extrusion forming force and can increase the extrusion deformation amount. The scheme obtains different workpieces or increases the extrusion deformation of a single workpiece by means of multiple reverse extrusions.

The above-mentioned patent is to form the shell-like workpiece by forward extrusion or reverse extrusion. The curved generatrix shell is a common workpiece in machining, which has the characteristics of large curvature change and thin wall thickness. Therefore, back extrusion is the preferred method for manufacturing curved generatrix shells. Although reverse extrusion forming can form a curved generatrix shell at one time, it has disadvantages such as uneven deformation of different parts and large differences in mechanical properties, especially the material dead zone formed at the bottom and the rigid translation zone formed at the mouth, and the deformation strain is small. poor mechanical properties.

SUMMARY OF THE INVENTION

The technical problem to be solved by the present invention is to provide a forward and reverse extrusion forming die and a forming method for a curved generatrix shell, so as to solve the problems of uneven deformation and large difference in mechanical properties after forming of the existing curved generatrix shell.

For solving the above problems, the technical scheme of the present invention is:

A forward and reverse extrusion forming die for a curved generatrix shell of the present invention comprises:

Extrusion punch for mounting on the upper formwork;

an extrusion die, which is used for being installed on the lower die plate, and the extrusion punch cooperates with the extrusion die to form a forming cavity;

The bottom of the forming cavity of the extrusion die is provided with a positive extrusion forming space, which is used to promote the forward flow of the material of the blank during extrusion;

The upper end of the inner wall surface of the forming cavity is provided with an overflow groove; the upper end of the outer wall surface of the extrusion punch is provided with a closing block, which is used to match the overflow groove to the blank in the forming cavity during extrusion. Make a closed squeeze.

In the forward and reverse extrusion forming die for the curved generatrix shell of the present invention, a material flow groove is provided on the bottom surface of the forming cavity.

The forward and reverse extrusion forming die of the curved generatrix shell of the present invention further comprises a top plate; the bottom surface of the forming cavity is provided with a top plate accommodating groove, and the top plate is arranged in the top plate container It is placed in the slot and is movably connected with the ejector plate accommodating slot; an ejection hole is arranged on the bottom surface of the ejector plate accommodating slot.

In the forward and reverse extrusion forming die of the curved generatrix shell of the present invention, the upper end of the ejector plate protrudes from the ejector plate accommodating groove and cooperates with the bottom surface and side wall surface of the forming cavity to form a material flow groove.

A forward and reverse extrusion forming method for a curved generatrix shell of the present invention uses the forward and reverse extrusion molding die for a curved generatrix shell described in any one of the above, and the specific steps are as follows:

S1: the upper die plate drives the extrusion punch to press down, and the blank at the lower end of the extrusion punch flows forward and fills the forward extrusion forming space;

S2: the extrusion punch continues to press down, and the blank at the lower end of the extrusion punch flows in reverse and fills the forming cavity;

S3; the extrusion punch is pressed down to close with the extrusion die, the closing block is clamped into the overflow groove, the blank is closed and extruded in the forming cavity, and the blank is simultaneously forward and reverse flow;

S4: After the extrusion is completed, the upper template drives the extrusion punch to move up to complete demolding.

Compared with the prior art, the present invention has the following advantages and positive effects due to the adoption of the above technical solutions:

1. In an embodiment of the present invention, a positive extrusion forming space is set at the bottom of the forming cavity of the extrusion die, so that when the extrusion punch moves downward, the blank at the lower end of the extrusion punch mainly flows in a positive direction and is gradually filled. The positive extrusion forming space, by controlling the distance between the blank and the bottom plate of the die, promotes the positive flow of the material and increases the strain of the dead zone material; and an overflow groove is set on the inner wall of the forming cavity, outside the extrusion punch. A matching closing block is arranged on the wall. When the extrusion punch is pressed down until the closing block is clamped into the overflow groove, the blank is closed and extruded in the forming cavity, and the blank flows forward and reverse at the same time. The closed extrusion can promote the positive flow of the material at the mouth and increase the strain amount of the material in the rigid translation zone, so as to achieve uniform material strain in different parts of the shell and uniform deformation of the curved generatrix shell; thus by increasing the dead zone of the material. The method of material flow and improvement of the mechanical properties of the rigid translation zone solves the problems of uneven deformation and large differences in mechanical properties that exist after the existing curved generatrix shell is formed.

2. In one embodiment of the present invention, a top plate and a top plate accommodating groove are arranged on the bottom surface of the forming cavity, and an ejection hole is provided on the bottom surface of the top plate accommodating groove, so that after the curved bus-shaped shell is formed, the , the ejector plate can be lifted through the ejection hole, so that the curved generatrix shell can be demolded, and the demolding process is simple and easy to operate.

3. In the first embodiment of this embodiment, the height of the ejector plate is skillfully set, so that the ejector plate is higher than the accommodating groove of the ejector plate, and cooperates with the forming cavity to form a material flow groove, which further increases the dead space of the material. Material flow ensures uniform deformation of the curved generatrix shell.

4. In the first embodiment of the present embodiment, the extrusion punch and extrusion die have simple structures, fewer steps for forming a curved busbar type shell, and a simple process flow, which is suitable for mass production of curved busbar type casings such as aluminum alloys and magnesium alloys.

Description of drawings

Fig. 1 is the mould design drawing and blank drawing of the present invention;

Fig. 2 is the extrusion forming part diagram of the present invention;

Fig. 3 is the schematic diagram of the material deformation process of finite element simulation of the present invention;

Fig. 4 is the schematic diagram of the material flow process of the finite element simulation of the present invention;

FIG. 5 is a schematic diagram showing the comparison of material strain distribution between the manufacturing method of the present invention and the conventional manufacturing method.

Description of reference numerals: 1: curved generatrix shell; 2: extrusion punch; 201: closing block; 3: extrusion die; 301: overflow groove; 4: blank; 5: positive extrusion forming space ; 6: ejector plate; 7: ejection hole; 8: material flow groove; 9: forming cavity.

Detailed ways

The forward and reverse extrusion forming die and forming method of a curved generatrix shell proposed by the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments. The advantages and features of the present invention will become apparent from the following description and claims.

Referring to Figure 1 and Figure 2, in one embodiment, a forward and reverse extrusion forming die for a curved generatrix shell includes an extrusion punch 2 mounted on the upper template and an extrusion die 3 mounted on the lower template. .

The bottom of the forming cavity 9 of the extrusion die 3 is provided with a positive extrusion forming space 5, which is used to promote the positive flow of the material of the blank 4 during extrusion. Taking the height of the forming cavity 9 as 1250 mm as an example, the required height of the positive extrusion forming space 5 is about 150 mm. Of course, the specific parameters of the positive extrusion forming space 5 can be adjusted according to the actual situation, which is not specifically limited here.

The upper end of the inner wall surface of the forming cavity 9 is provided with an overflow groove 301 . The upper end of the outer wall surface of the extrusion punch 2 is provided with a closing block 201, which is used to cooperate with the overflow groove 301 to close and extrude the blank 4 in the forming cavity 9 during extrusion. During closed extrusion, the upper part of the billet in forming is forward flow, the lower part is reverse flow, and the amount of deformation is small. Taking 1250mm as an example, the height of closed extrusion is about 20-30m, but the setting of closed extrusion can be significantly Improve the mechanical properties of the mouth of the curved generatrix shell after forming.

During forming, the extrusion punch 2 moves downward, and the blank 4 at the lower end of the extrusion punch 2 flows forward and fills the forward extrusion forming space 5 . The extrusion punch 2 continues to move downward, and the blank 4 on the side of the extrusion punch 2 flows in the reverse direction to form the main body of the curved generatrix shell 1 . The extrusion punch 2 is moved to the lowest position, the closing block 201 is stuck into the overflow groove 301, the blank 4 is closed and extruded in the forming cavity 9, and the blank 4 flows forward and reverse at the same time, completing the curved bus-shaped shell 1. Extruded.

Referring to FIGS. 3 , 4 and 5 , in this embodiment, a positive extrusion forming space 5 is provided at the bottom of the forming cavity 9 of the extrusion die 3 , so that when the extrusion punch 2 moves downward, the extrusion punch 2 is extruded. The blank 4 at the lower end mainly flows forward, and gradually fills the positive extrusion forming space 5. By controlling the distance between the blank and the bottom plate of the die, the forward flow of the material is promoted, and the strain amount of the dead zone material is increased. And an overflow groove 301 is set on the inner wall of the forming cavity 9, and a matching closing block 201 is set on the outer wall of the extrusion punch 2. When the extrusion punch 2 is pressed down until the closing block 201 is stuck into the overflow In the groove 301, at this time, the blank 4 is closed and extruded in the forming cavity 9, and the blank 4 flows forward and reverse at the same time. The closed extrusion can promote the forward flow of the material in the mouth and increase the strain of the material in the rigid translation zone. Thereby, the material strain of different parts of the shell is uniform, and the uniform deformation of the curved generatrix shell 1 is realized. Therefore, by increasing the material flow in the material dead zone and improving the mechanical properties of the rigid translation zone, the problems of uneven deformation and large differences in mechanical properties existing in the existing curved generatrix shell 1 after being formed are solved. At the same time, the extrusion punch 2 and the extrusion die 3 of this embodiment are simple in structure, have few steps for forming the curved busbar-type shell 1, and have a simple process flow, and are suitable for mass production of aluminum alloy, magnesium alloy and other curved busbar-type shells 1. .

The specific structure of the present embodiment is further described below:

In this embodiment, the positive extrusion forming space 5 can be realized by controlling the diameter of the bottom end of the blank 4 to match the diameter of the upper end of the positive extrusion forming space 5, that is, when the blank 4 is put into the forming cavity 9, the bottom of the blank 4 The end can only be moved to the upper end of the extruding space 5 .

In this embodiment, a material flow groove 8 may be opened on the bottom surface of the forming cavity 9 to increase the deformation of the bottom blank 4, so that the material flows further downward, thereby further increasing the material flow in the dead zone of the material. Taking the diameter of the forming cavity 9 as one meter as an example, the width of the material flow groove 8 is 30-50 mm, and the height is 70-90 mm. Of course, the specific parameters of the material flow tank 8 can be adjusted according to the actual situation, which is not specifically limited here.

In this embodiment, the front and back extrusion forming die can also be provided with a top plate 6 . A top plate accommodating groove is defined on the bottom surface of the forming cavity 9 , and the top plate 6 is arranged in the top plate 6 containing groove and is movably connected with the top plate 6 containing groove. At the same time, an ejection hole 7 is provided on the bottom surface of the accommodating groove of the ejector plate 6, so that after the curved generatrix shell 1 is formed, external components can be used to lift the ejector plate 6 through the ejection hole 7. In this way, the curved generatrix shell 1 can be demolded, and the demolding process is simple and easy to operate.

Further, the material flow channel 8 can be directly realized by the arrangement of the ejector plate 6 . It is only necessary to extend the upper end of the ejector plate 6 from the accommodating groove of the ejector plate 6 . At this time, the material flow groove 8 can be formed by cooperation between the top material plate 6 and the bottom surface and side wall surface of the forming cavity 9 to increase the material flow in the material dead zone and ensure the uniform deformation of the curved generatrix shell 1 .

Embodiment 2

Referring to FIG. 3 , a method for forward and reverse extrusion molding of a curved generatrix shell, using the forward and reverse extrusion molding die of the curved generatrix shell in the above-mentioned first embodiment, the specific steps are as follows:

S1: The upper die plate drives the extrusion punch 2 to press down, and the blank 4 at the lower end of the extrusion punch 2 flows forward and fills the positive extrusion forming space 5 to increase the strain of the dead zone material;

S2: The extrusion punch 2 continues to press down, and the blank 4 at the lower end of the extrusion punch 2 flows in reverse and fills the forming cavity 9;

S201: The extrusion punch 2 continues to be pressed down, and the blank 4 at the lower end of the extrusion punch 2 flows to the material flow groove 8, which further increases the material flow in the material dead zone to ensure the uniformity of the curved generatrix shell 1 deformation;

S3; the extrusion punch 2 is pressed down to close with the extrusion die 3, the closing block 201 is inserted into the overflow groove 301, the blank 4 is closed and extruded in the forming cavity 9, and the blank 4 is forward and reverse at the same time flow to promote the positive flow of the material at the mouth and increase the strain amount of the material in the rigid translation zone, so as to achieve uniform material strain in different parts of the curved generatrix shell 1 and achieve uniform deformation of the curved generatrix shell 1;

S4: After the extrusion is completed, the upper die plate drives the extrusion punch 2 to move up.

S401 : using an external component to lift the ejector plate 6 through the ejection hole 7 to lift the formed curved busbar shell 1 , so that the curved busbar shell 1 is released from the extrusion die 3 to complete demoulding. The embodiments of the present invention have been described in detail above with reference to the accompanying drawings, but the present invention is not limited to the above-mentioned embodiments. Even if various changes are made to the present invention, if these changes fall within the scope of the claims of the present invention and the technical equivalents thereof, they still fall within the protection scope of the present invention.

Claims (5)

1. The utility model provides a bent generating line shell forward and backward extrusion forming die which characterized in that includes:

the extruding male die is used for being arranged on the upper die plate;

the extrusion female die is used for being installed on the lower die plate, and the extrusion male die and the extrusion female die are matched to form a forming cavity;

the bottom of the forming cavity of the extrusion female die is provided with a forward extrusion forming space for promoting the forward flow of the material of the blank during extrusion;

an overflow groove is arranged at the upper end of the inner wall surface of the forming cavity; and the upper end of the outer wall surface of the extrusion male die is provided with a closed clamping block which is used for being matched with the overflow groove to carry out closed extrusion on the blank in the forming cavity during extrusion.

2. A positive and negative extrusion molding apparatus for a curved bus bar type casing as claimed in claim 1, wherein said molding cavity is provided with a material flow groove on a bottom surface thereof.

3. The forward-backward extrusion molding die for a curved bus bar type shell according to claim 1, further comprising an ejector plate; the bottom surface of the forming cavity is provided with a jacking plate accommodating groove, and the jacking plate is arranged in the jacking plate accommodating groove and is movably connected with the jacking plate accommodating groove; and the bottom surface of the ejector plate accommodating groove is provided with an ejector hole.

4. The forward-backward extrusion molding die for a curved bus bar type casing according to claim 3, wherein the upper end of the ejector plate protrudes from the ejector plate accommodating groove and cooperates with the bottom surface and the side wall surface of the molding cavity to form a material flow groove.

5. A forward and backward extrusion forming method of a curved busbar type shell is characterized in that the forward and backward extrusion forming die of the curved busbar type shell as claimed in any one of claims 1 to 4 is used, and the method comprises the following specific steps:

s1: the upper template drives the extrusion male die to press downwards, and the blank at the lower end of the extrusion male die flows in the forward direction and fills the forward extrusion forming space;

s2: the extrusion male die continues to be pressed downwards, and the blank at the lower end of the extrusion male die reversely flows and fills the forming cavity;

s3; the extrusion male die is pressed downwards to be matched with the extrusion female die, the closed clamping block is clamped into the overflow groove, the blank is extruded in a closed manner in the forming cavity, and the blank flows forwards and reversely at the same time;

s4: and after the extrusion is finished, the upper die plate drives the extrusion male die to move upwards to finish the demoulding.

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