JP2000225434A - Method for creating intermediate blank shape for forged parts and method for designing die for forging - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a creating method for an intermediate blank shape, with which the intermediate shape suitable to the shape in the case of giving the new shape of forged parts can be created without using the past data on the similar product, and a designing method for a forging die therefore. SOLUTION: A target shape is divided into block pieces having square cross section (No.1) and the vol. of each block piece is calculated (No.2). Then, each block piece is replaced into a rectangular parallelepiped of a high based on the vol. (No.3) and the vertex of each rectangular parallelepiped is arranged (No.4). Further, the profile of a target shape is disposed. Then, the curved line group is constituted by connecting each vertex and a profile line and further, the curved surface is constituted (No.5). The machining surface shapes for the intermediate blank shape and the forging die are decided with this curved surface.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a forging process in which a raw material having an initial shape is pressed into a target shape by a die.
More specifically, a material having an initial shape is first processed into a shape intermediate between the initial shape and a target shape, and then a method for creating an intermediate material shape when processing the material into a target shape, and a forging die for that purpose. It concerns the design method.

[0002]

2. Description of the Related Art Conventionally, when a metal or other plastic material is forged and shaped into a target shape, a material having an initial shape is first processed into an intermediate shape between the initial shape and the target shape, and the target shape is further processed. It may be processed into a shape. This is because if the initial shape and the target shape are relatively far from each other, it is impossible to process them all at once.

A method for determining an intermediate shape for this purpose is described in Japanese Patent Application Laid-Open No. Hei 9-234536.
The method described in this publication is roughly as follows. That is, for a known forged product, the rod-shaped data of the shape (target shape) and the shape (intermediate shape) in the previous process are accumulated in a database in advance. Then, when a new forged product shape (target shape) is given, a known forged product having a shape similar to this (target shape) is selected from the database, and the shape (intermediate shape) in the preceding process is selected. Based on this, the shape (intermediate shape) of the new forged product in the previous process is determined. In this way, the determination of the intermediate shape, which has long relied on the experience and intuition of the designer, is intended to be more efficient.

[0004]

However, the above-mentioned conventional method has the following problems. In other words, since it is based on the shape of the known forged product in the previous process,
It is not always possible to create an intermediate shape suitable for the target shape of a new forged product. In particular, it cannot be applied when there is no known forged product similar to the new forged product in the database.

[0005] The present invention has been made to solve the above-mentioned problems of the prior art. That is, the problem is that when a new shape of a forged part is given, an intermediate shape suitable for the shape can be created without data of similar products in the past, and a method of creating an intermediate material shape, and forging for that purpose. An object of the present invention is to provide a method for designing a metal mold.

[0006]

SUMMARY OF THE INVENTION An object of the present invention is to provide a method for creating an intermediate material shape in the process of forging a material from an initial shape to a target shape, or a method for forming a material into an initial shape. (1) a method for designing a forging die for an intermediate material shape in the process of forging to a target shape from a target shape, wherein the target shape is divided into blocks perpendicular to a predetermined reference plane; , A step (2) of calculating the volume of each block divided in the step (1), a step of arranging vertices of a height based on the volume calculated in the step (2) for each block, and (3) (4) to form a curve group by connecting to a curve, and the curved surface represented by the curve group in the step (4) is defined as an intermediate material shape or a concave shape of a forging die.

In this method, when a new target shape of a forged part is given, the target shape is divided into blocks perpendicular to a predetermined reference plane (step (1)). That is, first, a reference plane is assumed. The reference plane is a plane orthogonal to the direction in which the material is compressed by the die during forging. Then, a large number of regions (usually a square shape) filling this reference plane without gaps or overlaps are assumed. Then, the target shape is divided into a number of blocks that fit in the area by being projected perpendicularly to this reference plane.

Next, the volume of each of the divided blocks is calculated (step (2)). This calculation can be performed by integrating the height coordinates of each point representing the surface of the target shape in the block.

Then, vertices are arranged for each block based on the calculated volume (step (3)). That is, a vertex having a height based on the volume of the block is arranged for each area of the reference plane. For this purpose, instead of each block, a columnar body having a height based on the volume of the block may be arranged in each region of the reference plane, and the center of the top surface of each columnar body may be set as the vertex. In this case, the height of each column may be determined such that the volume of the column is equal to the volume of the block to be replaced. In that case, the height of the column represents the average of the height of each point in the area of the block. Alternatively, correction may be made in consideration of factors such as the position of the block in the entire target shape and the volume of adjacent blocks.

Then, each vertex is connected by a curve. Further, a curve group is formed by creating a plurality of these curves (step (4)). This curve group reflects the target shape to some extent. Therefore, a curved surface that includes the curve group may be an intermediate material shape or a concave shape of a forging die.

In the step (4) of the present invention, it is desirable to form a curve group by connecting not only vertices but also points on the contour of the projection of the target shape onto the reference plane by curves. By doing so, the constituted curve group always comes into contact with the reference plane at the position of the contour. Therefore, the shape of the intermediate material or the outer periphery of the forging die becomes clear.

Further, in the present invention, it is preferable that the method further includes a step (5) of deleting a portion outside the contour of the figure obtained by projecting the target shape on the reference plane for the curve group formed in the step (4). The portion outside the contour is formed when the points are connected in step (4), but is unnecessary in the actual intermediate material shape and the forging die. By performing the step (5), this unnecessary portion is trimmed.

In the configuration of the curve group in the step (4) of the present invention, it is preferable to configure the curve group corresponding to the parallel straight line group on the reference plane. Usually, the area division of the reference plane for dividing the target shape into blocks is performed by two sets of equidistant parallel straight lines that are orthogonal to each other. Therefore, on the reference plane, a straight line group parallel to one of the parallel straight line groups and shifted by a half interval is assumed, and a curve group may be formed by connecting the vertices above the straight line group. As a result, a curve group can be formed by reflecting each point without fail.

[0014]

Embodiments of the present invention will be described below in detail with reference to the drawings. In the present embodiment, taking a product (connecting rod for engine) 10 having the shape shown in FIG. 1 as an example, an intermediate material shape and a mold shape for forming this shape (target shape) by two-stage forging are described. Create. An outline of the creation procedure is shown in the flowchart of FIG. In general, forged parts of this kind are arranged such that two parts are alternately arranged as shown in FIG.
As a set, it is manufactured from one billet.

(# 1) First, a three-dimensional shape of a product is required. What is needed is the three-dimensional coordinates of each point on the surface of the product. This data is obtained from the department that designs the product, and read into the computer that executes this procedure. First, block division is performed on the acquired three-dimensional shape. That is, the three-dimensional shape is divided into blocks each having a square cross section perpendicular to the reference plane by two sets of equidistant parallel plane groups orthogonal to each other. FIG. 4 shows this as viewed from above perpendicularly to the reference plane. In FIG. 4, two sets of parallel planes that divide the three-dimensional shape appear as a grid pattern. In this example, the three-dimensional shape is divided into 10 mm square blocks. FIG. 5 shows an example of the divided block pieces 11. Note that the reference plane is a plane at the center in the thickness direction of the three-dimensional shape of the product. The reference plane is also a plane on which upper and lower molds meet during actual forging.

In this embodiment, as described above, two sets are alternately arranged as one set. This state can be grasped as a state where the same shape is rotated by 180 ° and joined at the line AA in FIG. Therefore, creation of an intermediate material shape or the like may be performed for only one of them, and then copied symmetrically later. Therefore, FIG. 4 shows only one of them. Further, the three-dimensional shape of the product in the present embodiment is plane-symmetric with respect to the reference plane. Therefore, it is only necessary to create an intermediate material shape or the like for only one of the upper side and the lower side of the reference plane, and copy it symmetrically later. For this reason, the block piece 11 shown in FIG. 5 is also only on one side. That is, the bottom surface 1 of the block piece 11
1B corresponds to the reference plane. Further, the top surface (facing the bottom surface 11B) 11T of the block piece 11 corresponds to the three-dimensional surface of the product.

(# 2) Subsequently, the volume of each block piece 11 is calculated. This calculation is performed by integrating the distance on the vertical line (line perpendicular to the reference plane) between the bottom surface 11B and the top surface 11T for each point on the bottom surface 11B of the block piece 11. That is, since the height coordinate of each point on the top surface 11T is included in the data of the three-dimensional shape of the product, it may be numerically integrated for each point on the bottom surface 11B. This volume calculation is performed for all block pieces.

(# 3) After the volume of each block piece 11 is obtained, the block piece 11 is replaced with a rectangular parallelepiped 12 as shown in FIG. The rectangular parallelepiped 12 is
1 has the same horizontal cross section as the horizontal cross section (ie, the square of the grid pattern in FIG. 4), and
It is a rectangular parallelepiped having a volume obtained by multiplying a volume of 1 by a predetermined coefficient. The predetermined coefficient is usually a number of about 1 to 1.2,
The determination is made in consideration of factors such as the position of the block in the entire target shape and the volume of blocks adjacent to the periphery.
Since this coefficient is a number close to 1, the height of the rectangular parallelepiped 12 substantially reflects the average height of the top surface 12T of the replaced block piece 11. This replacement with a rectangular parallelepiped is performed for all the block pieces.

(# 4) Then, the center point (hereinafter referred to as "vertex") 12C of the top surface of each rectangular parallelepiped is arranged with respect to the reference plane (FIG. 7). In FIG. 7, each vertex is arranged at the position of the in-plane coordinates of the center of the original block piece 11 and the height coordinates of the vertex 12C of the rectangular parallelepiped 12 replaced with the block piece 11. When this state is viewed from above, as shown in FIG. 8, each vertex 12C is located at the center of each square of the grid pattern of the block division. Further, in addition to this state, a contour of the product shape, that is, an intersection line between the surface of the product shape and the reference plane is arranged (FIG. 9). In the state of FIG. 9, the contour is arranged in the reference plane. The reason for arranging the contours in this manner is to prevent an unnecessary portion from protruding outside the product shape from being generated in the created intermediate material shape.

(# 5) BB in FIG. 8 in the state up to # 4
Taking a sectional view, as shown in FIG. 10, there is a situation where some vertices 12C are arranged above the reference plane. Further, contour points 13 and 13 are located on the reference plane outside of them in the left-right direction. Therefore, FIG.
The upper vertex 12C and the contour points 13 and 13 are connected by a smooth curve 14. This connection is performed by obtaining a known spline curve passing through each vertex 12C and the contour points 13, 13.

The vertices 12C and the contour points 13 are similarly connected on another straight line in which one of the grid patterns is shifted by a half cycle in parallel with the line BB in FIG. Thereby, a curve group is obtained as shown in FIG. This curve group reflects all vertices 12C arranged in # 4. Further, all the intersections between the outline and the straight line group parallel to the BB line in the grid pattern are also reflected. Further, a curved surface that envelopes the curve group is formed (FIG. 12). The constructed curved surface is a rough approximation of the product shape. Thus, the surface is formed based on the vertices 12C arranged in # 4. In this method, this curved surface is used as the surface shape of the intermediate material. At this time, for each point on the reference plane, the height coordinate of the intersection between the normal and the curved surface is given.

This curved surface is smooth without any sharp points. This curved surface always intersects the reference plane at the contour of the product shape. This is because the configuration includes the contour arranged in # 4.

(# 6) Next, solidification is performed. That is, the space between the curved surface created in # 5 and the reference plane is filled.

(# 7) Next, trimming is performed. That is, of the solid created in # 6, the portion outside the contour of the product shape is deleted (FIG. 13). As a result, unnecessary portions outside the product shape are removed. However, 2
The region sandwiched between the components arranged in this way is not removed. The shape obtained in this way is not a cliff at the contour. This is because the curved surface constituted by # 5 always intersects the reference plane at the contour of the product shape. Then, when this is symmetrically copied front and back and front and back, FIG.
As shown in (2), the entire intermediate material shape is completed.

(# 8) Finally, the volume is verified. That is, for each point inside the intermediate material shape in FIG. 14 on the reference plane, the height coordinates obtained in # 5 are integrated.
If the volume obtained as a result falls within a predetermined allowable range with respect to the volume of the target shape of the product (# 8: Yes), the process is completed. If the volume is significantly out of the target shape of the product (# 8: No), the process returns to # 4 and starts over. At this time, the height coordinates of each vertex are readjusted according to the degree of deviation of the volume.

At the time of this volume verification, the volume may be verified for each part whose shape is cut along the curve group in FIG. In this case, if there is at least one sliced portion whose volume is not within the allowable range, the process returns to step # 4 and starts over. Then, the height coordinates of each vertex 12C belonging to the portion are readjusted. Then, in step # 5, the connection (FIG. 10) is re-performed with the spline curve for that portion. The configuration of the curved surface is redone not only for that part but also for the entire shape.
By repeating this process so that the volume of any of the round sections falls within the allowable range, an intermediate material shape more suitable for the target shape can be obtained.

Thus, an intermediate material shape (FIG. 14) is obtained. In addition, the processing surface shape of the mold for obtaining the intermediate material shape can be obtained. That is, one side of the shape shown in FIG. 14 with the reference plane as the boundary may be used as the processing surface shape of the mold. The mold obtained in this way has an intermediate material shape with a curved surface appropriately distributed in volume. Therefore,
The billet, which is a material, may be first forged into the shape shown in FIG. 14 by using this mold, and finally forged into the target shape. In this way, the material flows smoothly during the forging process, and the product shape can be obtained without difficulty. In addition, the moldability is improved and the life of the mold is extended.

As described in detail above, in the present embodiment, the vertices 12C are arranged based on the volume of each block piece 11 obtained by dividing the target shape into elements having a square cross section, and a curve is formed by each of these vertices 12C. A group is formed, and a curved surface is formed (surfaced) to obtain an intermediate material shape. In addition, this curved surface is used as a processed surface shape of the mold. Therefore, if the target shape is given, the intermediate material shape and the processed surface shape of the mold can be uniquely obtained. Therefore, even if the target shape is a new shape that has never been seen before, as long as the shape is given, the intermediate material shape can be determined without referring to the data of similar products in the past. Further, by using a mold having the intermediate material shape as the processing surface shape, the material can be easily made into the intermediate material shape (so-called rough land). Thus, a method of obtaining the shape of the intermediate material and the shape of the processed surface of the die without relying on the accumulation of past data and the experience and intuition of the designer has been realized.

Here, not only each vertex 12C based on the volume of each block piece 11 but also the contour point 13
Is taken into account, a curved surface which intersects with the reference plane is always formed at the contour of the target shape. Then, after the curved surface is formed, a portion outside the contour of the target shape is removed. For this reason, the obtained curved surface does not have an unnecessary portion protruding outside the outline of the target shape, and does not have a cliff at the outline. Thereby, a highly realistic intermediate material shape and a processed surface shape of the mold can be obtained.

Also, since a curve group is formed by connecting the vertices 12C and the contour points 13 on a straight line group obtained by shifting one straight line group of the grid pattern for subdividing the target shape by half a cycle, a curved surface is formed. , Each vertex 12C is completely reflected on the curved surface. For this reason, the shape of the intermediate material and the shape of the processing surface of the mold more suitable for the target shape can be obtained.

Further, according to the present method, the intermediate material shape and the forging die based on the intermediate material shape can be designed by directly using the three-dimensional model data of the product designed by the designer. As a result, the number of design steps can be significantly reduced.

The above embodiment is merely an example, and does not limit the present invention in any way. Therefore, naturally, the present invention can be variously modified and modified without departing from the gist thereof. For example, the cross-sectional shape of the block section is not necessarily a square shape, and may be any shape as long as it can fill the space without any gap. In addition, it is not essential to process the two connecting rods in a staggered state. Of course, the target shape to be processed is not limited to the connecting rod, but may be another shape.

The method of the present invention is further applicable to a process in which forging is performed in three stages. That is, the method of the present invention is applied to the final target shape to obtain a second intermediate shape (and a processing surface shape of a mold therefor), and the method of the present invention is applied to the second intermediate shape as a target shape. What is necessary is just to apply and obtain the 1st intermediate | middle shape (and the processing surface shape of the metal mold | die therefor). Of course, it can be applied to a multi-step processing process.

[0034]

As is apparent from the above description, according to the present invention, when a new shape of a forged part is given, an intermediate shape suitable for the shape is created without data of similar products in the past. A method for creating a possible intermediate material shape and a method for designing a forging die therefor are provided.

[Brief description of the drawings]

FIG. 1 is a perspective view showing a shape of a connecting rod which is a target shape for forging.

FIG. 2 is an explanatory view of a state in which two connecting rods are alternately arranged.

FIG. 3 is a flowchart illustrating a procedure of a curved surface configuration according to the present embodiment.

FIG. 4 is a diagram for explaining block division of a target shape.

FIG. 5 is a diagram illustrating an example of a divided block piece.

FIG. 6 is a diagram showing a process of replacing a block piece with a rectangular parallelepiped.

FIG. 7 is a diagram showing a situation where vertices of a rectangular parallelepiped are arranged.

FIG. 8 is a diagram showing a state where the vertices of a rectangular parallelepiped are arranged, as viewed from above.

FIG. 9 is a diagram showing a situation where a contour of the shape of a connecting rod is arranged.

FIG. 10 is a diagram showing a process of forming a curve by connecting vertices and contour points.

FIG. 11 is a diagram showing a configured curve group.

FIG. 12 is a diagram showing a state where a curved surface is formed by curve groups and surfaced.

FIG. 13 is a diagram showing a state where an unnecessary portion is trimmed.

FIG. 14 is a diagram showing a symmetrically copied state.

[Explanation of symbols]

 11 block piece 12 rectangular parallelepiped 12C vertex 13 contour point 14 curve

Continued on the front page (72) Inventor Shuji Higaki 1 Toyota Town, Toyota City, Aichi Prefecture Toyota Motor Corporation F-term (reference) 4E050 JA00 JA08 JB02 JB10 JC00 JC05 JD05 4E087 AA10 BA11 CA00 CB00 CB11 DA02 EC00 ED01 GA01 GA20 HB17 5B046 AA05 DA02 DA10 FA12 FA18

Claims (8)

[Claims] In a method for creating an intermediate material shape in a process of forging a material from an initial shape to a target shape, a step (1) of dividing the target shape into blocks perpendicular to a predetermined reference plane. , A step (2) of calculating a volume of each block divided in the step (1), and a step of arranging vertices of a height based on the volume calculated in the step (2) for each of the blocks; (4) forming a curve group by connecting each vertex with a curve, wherein the curved surface represented by the curve group is formed into an intermediate material shape. 2. The method according to claim 1, wherein in step (4), the vertices and points on the contour of the projection of the target shape onto the reference plane are curved. A method for creating an intermediate material shape of a forged part, characterized by forming a group of curves by connecting with each other. 3. The method for creating an intermediate material shape of a forged part according to claim 1 or 2, wherein a projection of the target shape onto the reference plane is obtained for the curve group formed in step (4). A method for creating an intermediate material shape of a forged part, comprising a step (5) of deleting a portion outside a contour. 4. One of claims 1 to 3
In the method for creating an intermediate material shape of a forged part described in (1), in step (4), a group of curves is formed corresponding to a group of parallel straight lines on the reference plane, wherein Creation method. 5. A method of designing a forging die for an intermediate material shape in a process of forging a material from an initial shape to a target shape, wherein the target shape is formed into a block perpendicular to a predetermined reference plane. Step (1) for dividing and step (1)
Of calculating the volume of each block divided by (2)
And arranging vertices of height based on the volume calculated in step (2) for each of the blocks (3), and forming a curve group by connecting the vertices with a curve (4), A method for designing a forging die, wherein the curved surface represented by the curve group is a concave shape of the forging die. 6. The method for designing a forging die according to claim 5, wherein in the step (4), the vertexes and points on the contour of the projection of the target shape onto the reference plane are connected by a curve. A method for designing a forging die, wherein a curve group is constituted by: 7. The method for designing a forging die according to claim 5, wherein the curve group formed in the step (4) is obtained from a contour of a projection of the target shape onto the reference plane. A method for designing a forging die, comprising a step (5) of removing an outer portion. 8. One of claims 5 to 7
In the method for designing a forging die according to the first aspect, in the step (4), a group of curves is formed corresponding to a group of parallel straight lines on the reference plane.