JP2021159936A - Manufacturing method of hot press forming die - Google Patents

Abstract

To inhibit displacement of the curved tubes at the lowest possible cost at casting of the curved tubes to obtain a hot press molding die.SOLUTION: A manufacturing method of a hot press molding die comprises: steps (S3, S4) of creating 3D-data of a curved tube by 3D-scanning the curved tubes; a step (S5) of creating 3D-data of a model that imitates a mold, using the 3D-data of the curved tubes; a step (S6) of creating the model using the 3D-data of the model; a step (S7) of arranging actual curved tubes in the created model; and steps (S8, S9) of filling the model with casting sand so as to form the mold after the step of arranging the curved tubes, and pouring molten metal into the mold. In the model, holes are formed in portions where the curved tubes are arranged. The 3D-data of the model includes 3D-data of the holes having shapes that match the 3D-data of the curved tubes.SELECTED DRAWING: Figure 3

Description

The technology disclosed herein belongs to the technical field relating to a method for manufacturing a mold for hot press molding.

Conventionally, a method of manufacturing a mold by casting a curved pipe having a curved portion has been known.

For example, in Patent Document 1, in a method of manufacturing a mold by fixing and casting the end of a bent cooling circuit, the cooling circuit tube is bent in an annular shape in a direction away from the cavity surface of the mold. Those provided with the provided thermal expansion buffer are disclosed.

In Patent Document 1, the cooling circuit tube is arranged in the cavity of the mold with the end fixed.

Japanese Unexamined Patent Publication No. 2016-30276

By the way, in a mold for hot press molding, it is necessary to arrange a metal tube in the vicinity of the shape surface of the mold in order to improve the cooling efficiency of the molded product and the mold during hot press molding. Therefore, the metal pipe becomes a curved pipe having a curved portion along the shape surface. The curved pipe is likely to be displaced due to thermal deformation at the curved portion, and if the curved pipe is displaced, the cooling efficiency is lowered.

Patent Document 1 attempts to suppress misalignment of a portion of a curved pipe near a shape surface by providing a thermal expansion buffer. However, it is difficult to predict the degree of deformation of the curved tube in advance and provide the thermal expansion buffer, and there is a possibility that misalignment may occur at the time of arranging the curved tube in the mold. In addition, since a portion that does not contribute to cooling of the press-molded product is provided, the cost is deteriorated.

The technique disclosed herein has been made in view of these points, and the purpose thereof is to obtain a die for hot press molding by casting a curved tube at the lowest possible cost. The purpose is to suppress misalignment.

In order to solve the above problems, the first aspect of the technique disclosed herein is a mold for hot press molding in which a metal curved tube having at least one curved portion is cast to manufacture a mold. For the manufacturing method, a curved tube data creation step of 3D scanning the curved tube to create 3D data of the curved tube, and 3D of a model imitating the mold using the 3D data of the curved tube. A model data creation step for creating data, a model creation step for creating the model using the 3D data of the model, a curved tube placement step for arranging the actual curved tube in the created model, and the curved tube After the arranging step, the model includes a casting step of filling the model with casting sand to form a mold and pouring molten metal into the mold, and the model has a hole formed in a portion where the curved pipe is arranged. The model data creation step is a step of creating 3D data of the model including 3D data of a hole having a shape matching the 3D data of the curved tube.

A second aspect of the technique disclosed herein is, in the first aspect, a curved tube manufacturing step of bending a straight metal tube to obtain the curved tube before the curved tube data creation step. It is characterized by including.

A third aspect of the technique disclosed herein is that, in the first or second aspect, there are a plurality of the curved pipes, and the intermediate portions of the curved pipes are connected to each other by a connector before the curved pipe data creation step. The curved pipe data creation step further includes a curved pipe connecting step of connecting, and is a step of 3D scanning a curved pipe group composed of the plurality of connected curved pipes to create 3D data of the curved pipe group. The model data creation step is a step of creating 3D data of the model so that the hole matching the shape of the curved tube group is formed by using the 3D data of the curved tube group. It is characterized by.

According to the first aspect of the technique disclosed herein, 3D data of a curved pipe can be created, and the shape of a hole in which the curved pipe is arranged can be determined based on the 3D data of the curved pipe. As a result, a hole matching the shape of the curved tube is formed in the model, and the curved tube can be accurately placed in the model. As a result, it is possible to suppress the misalignment of the curved tube in the hot press molding die.

That is, conventionally, when creating 3D data of a model, the shape of the curved tube is virtually determined and created. In this case, the shape of the hole in which the curved pipe is arranged is also determined according to the shape of the virtual curved pipe. Therefore, when arranging the actual curved pipe in the actual model, the shape of the hole may not match the shape of the actual curved pipe, and the position of the curved pipe may shift at this stage. On the other hand, in the above technique, the compatibility between the hole of the actual model and the actual curved tube can be considerably improved. Therefore, it is possible to suppress the misalignment of the curved tube in the hot press molding die.

Further, since it is only necessary to add the step of acquiring the 3D data of the curved pipe, the increase in cost can be suppressed as much as possible.

According to the second aspect of the technique disclosed herein, since the curved tube is obtained by bending a straight metal tube, the degree of curvature of the curved tube is likely to vary from one to another. If a model is created using the 3D data of the curved pipe obtained by the bending process, the shape of the hole can be adjusted according to such a difference in the individual shapes. Therefore, the misalignment of the curved tube in the hot press molding die can be suppressed more effectively.

According to the third aspect of the technique disclosed herein, when there are a plurality of curved pipes, the curved pipes are connected to each other by a connecting tool to form a curved pipe group, so that the pitch shift between the curved pipes is suppressed. can do. Further, the shape of the hole in which the curved pipe group is arranged becomes complicated as compared with the case where one curved pipe is arranged. On the other hand, if the 3D data of the curved tube group is acquired and the shape of the hole is determined based on the 3D data, the compatibility between the hole of the actual model and the actual curved tube group can be improved. Can be high. This makes it possible to more effectively suppress the misalignment of the curved tube in the hot press molding die.

It is a perspective view which shows the die for hot press molding which concerns on an exemplary embodiment. It is a top view of the hot press molding die. It is a flowchart of manufacturing the die for hot press molding. It is a schematic diagram which shows the state of 3D scanning the curved tube group. In the 3D data of the model, it is a cross-sectional view cut by a plane including a hole where a group of curved pipes is arranged. It is a divided plan view which shows the state which the model is divided. It is a side view which shows the state which the curved tube group is arranged in the half part of a model. It is a schematic diagram which shows the state which formed the mold.

Hereinafter, exemplary embodiments will be described in detail with reference to the drawings. The following description of the preferred embodiment is essentially merely an example.

<Mold for hot press molding>
FIG. 1 shows a hot press molding die 1 (hereinafter referred to as a die 1) manufactured by the manufacturing method according to the present embodiment. In the following description, up, down, right, left, front, and back follow the arrows in FIG.

The die 1 is one of the dies constituting the lower die of the hot press device including the upper die and the lower die. The mold 1 is used, for example, when molding a body part of an automobile. In this embodiment, the mold 1 is manufactured by casting.

The upper side surface of the mold 1 is a shape surface 1a for molding a press-molded product. The shape surface 1a of the mold 1 has a first curved surface 1b that curves upward toward the rear so as to be convex downward, and a first curved surface 1b that curves downward toward the rear so as to be convex upward. It has a second curved surface 1c.

As shown in FIG. 2, the shape surface 1a of the mold 1 is curved not only in the vertical direction but also in the horizontal direction. Specifically, it is curved to the left toward the rear side.

A plurality of curved pipes 10 (here, two curved pipes 10) for circulating the cooling medium are embedded in the mold 1. Specifically, the two curved pipes 10 are arranged side by side in the vertical direction. For each curved pipe 10, for example, a carbon steel pipe for machine structure is used. As each curved tube 10, for example, a tube having an inner diameter of 10 mm or more and a wall thickness of 1.5 mm or more is used. Each curved tube 10 is cast in the mold 1. The method of casting each curved pipe 10 into the mold 1 will be described later.

Each curved tube 10 has a curved portion along the shape surface 1a. Specifically, each curved tube 10 is provided in a portion corresponding to the first curved surface 1b and bent upward, and a portion corresponding to the second curved surface 1c. It also has a second curved portion 12 that is bent downward. The first curved portion 11 and the second curved portion 12 are each formed by bending a straight metal pipe, particularly by manually bending the metal pipe.

Further, as shown in FIG. 2, each curved tube 10 is bent to the left side toward the rear side so as to match the shape of the shape surface 1a.

The two curved pipes 10 are arranged side by side in the vertical direction. The curved pipes 10 are connected to each other by a plurality of connecting tools 13 (here, three connecting tools 13) to form a curved tube group 100. Each connector 13 is made of a metal plate. Each connector 13 is welded to the right side portion of each curved pipe 10. Each connecting tool 13 is arranged at one end of the radius of the first and second curved portions 11 and 12, and at an intermediate portion of the second curved portion 12, respectively.

Each connector 13 is cast into the mold 1 together with the curved pipe group 100. That is, each connector 13 is embedded in the mold 1. By embedding each connector 13 in the mold 1, each connector 13 can assist heat conduction from the press-molded product to the cooling medium flowing in the curved tube 10 during hot press molding. .. As a result, the cooling efficiency of the press-molded product can be improved. The connecting tool 13 is not particularly limited as long as it is made of a material that is not melted by the molten metal, but it is preferably made of the same metal as the curved tube 10.

<Manufacturing method of hot press molding die>
Next, a method of manufacturing the mold 1 by casting will be described with reference to the flowchart of FIG.

First, in step S1, the curved pipe 10 to be cast into the mold 1 is manufactured. In step S1, the straight metal tube is bent so as to conform to the shape surface 1a. In the present embodiment, the curved tube 10 is obtained by manually bending a straight metal tube.

Next, in step S2, the intermediate portions of the curved pipes 10 are connected to each other by the connecting tool 13. Each connecting tool 13 is joined to the curved pipe 10 to be connected by welding. Each connector 13 is attached to one end of the radius of the first and second curved portions 11 and 12, respectively. As a result, the curved tube group 100 is obtained. In this embodiment, since there are two curved pipes 10 arranged in the mold 1, all the curved pipes 10 are connected by the connecting tool 13. However, when more (that is, three or more) curved pipes 10 are arranged, it is only necessary to connect the curved pipes 10 when the distance between the curved pipes 10 is less than a predetermined distance, and the curved pipes 10 which are largely separated from each other are connected. It does not have to be.

Next, in step S3, the curved tube group 100 obtained in step S2 is 3D scanned. The 3D scan of the curved tube group 100 is performed, for example, by photographing the entire curved tube group 100 at 360 ° with the camera C, as shown in FIG. The 3D scan is performed so that the shapes of the first and second curved portions 11 and 12 are reflected in the curved tube data 101 described later. In the 3D scan, the entire curved tube group 100 including the connector 13 is scanned.

Subsequently, in step S4, 3D data of the curved tube group 100 (hereinafter referred to as curved tube data 101) is created from the data scanned in 3D in step S3.

Next, in step S5, 3D data (hereinafter referred to as model data 200) of the model 20 (see FIG. 6) imitating the mold 1 is created based on the curved tube data 101. In this step S5, in particular, based on the curved pipe data 101, 3D data of the shape of the hole 21 (see FIG. 7) in which the curved pipe group 100 in the model 20 is arranged is created. Specifically, 3D data of a hole having a shape matching the shape of the curved pipe group in the curved pipe data 101 is created. As shown in FIG. 5, in the model data 200, the shape of the hole is created so that the inner surface of the hole matches the outer peripheral surface of the curved tube data 101. At this time, in the model 20, the shape of the groove into which the connector 13 is fitted is also created on the model data 200. In FIG. 5, a gap is provided between the inner surface portion of the hole portion and the curved tube data 101 in order to make the shape of the hole portion easy to see, but in reality, there is almost no such gap.

Next, in step S6, the model 20 is created based on the model data 200. The model 20 is formed by processing a foam material by machining based on the model data 200. As shown in FIG. 6, the model 20 is created in a state where the hole 21 is divided into two along the hole shaft 21a (see FIG. 7). As shown in FIG. 7, each half portion 20a is formed with a groove forming the hole portion 21, and one hole portion 21 is formed by combining the grooves of each half portion 20a. A groove into which the connector 13 is fitted is formed in one of the half portions 20a. The material of the model 20 is not particularly limited, and may be made of another material as long as it is easy to process and can be melted by molten metal.

Subsequently, in step S7, the curved pipe group 100 is arranged in the hole 21 of the model 20. At this time, the curved pipe group 100 is arranged in one half portion 20a so that each connector 13 fits into the fitting groove 21b. As a result, the curved pipe group 100 is arranged at an appropriate position. In particular, since the hole 21 is formed based on the curved tube data 101, as shown in FIG. 7, substantially the entire hole 21 is in a state suitable for the curved tube group 100. After arranging the curved pipe group 100 in one half portion 20a, the other half portion 20a is put together and the half portions 20a are joined to each other. As a result, the model 20 in which the curved pipe group 100 is arranged is completed, and the curved pipe group 100 is fixed to the model 20. In FIG. 7, as in the case of FIG. 5, a gap is provided between the inner surface portion of the hole portion 21 and the curved pipe group 100 in order to make the shape of the hole portion 21 easy to see. Actually, there is almost no gap, and the upper surface and the lower surface of the hole 21 are in contact with the curved pipe group 100 as a whole. Further, as shown in FIGS. 7 and 8, immediately before or after arranging the curved tube group 100 on the model 20, the curved tube group 100 is placed on both side ends of the curved tube group 100 in a mold 50 described later. The stoppers 30 for fixing the stoppers 30 are welded to each other.

Next, in step S8, the mold 50 is formed of casting sand so as to cover the model 20 including the curved pipe group 100. As shown in FIG. 8, the casting sand is filled so as to fill the model 20 and the curved pipe group 100 in a state where the model 20 is turned upside down together with the curved pipe group 100. As a result, the cavity 51 having the cavity surface 51a along the surface of the model 20 is formed. When forming the mold 50, some load is applied to the model 20 and the curved tube group 100. On the other hand, in the present embodiment, since the curved pipe group 100 is fixed by the hole portion 21, the curved pipe group 100 and the model 20 are difficult to move relative to each other even if a slight load is applied, and the curved pipe group 100 is curved. The tube group 100 is less likely to be misaligned with respect to the model 20. Although not shown, the mold 50 is formed with a sprue for pouring molten metal into the cavity 51. Although not shown, lids are provided on both side ends of the hole 21 in the hole axis direction to prevent casting sand from entering the hole 21. Further, the mold 50 may be formed without turning the model 20 upside down.

Then, in step S9, the molten metal is poured into the cavity 51. The molten metal is accumulated in the cavity 51 while melting the model 20. At this time, each curved tube 10 is deformed by the heat of the molten metal and tries to move in the cavity 51. However, since the curved pipes 10 are connected to each other by the connecting tool 13, the deformation of each curved pipe 10 is suppressed, and the pitch between the curved pipes 10 is maintained. As a result, it is possible to prevent the curved tube group 100 from being displaced from the desired position.

Then, after the molten metal has solidified, the mold 50 is crushed in step S10. After crushing the mold 50, the mold 1 is taken out from the mold 50. After that, the surface of the mold 1 is slightly scraped off to complete the mold 1.

Therefore, in the present embodiment, the curved tube data creation step (steps S3 and S4) for creating the curved tube data 101 which is the 3D data of the curved tube 10 by 3D scanning the curved tube 10 and the curved tube data 101 are used. A model data creation process (step S5) for creating model data 200, which is 3D data of the model 20 imitating the mold 1, and a model creation process (step S6) for creating the model 20 using the model data 200. After the curved pipe arranging step (step S7) of arranging the actual curved pipe 10 in the created model 20 and the curved pipe arranging step, the model 20 is filled with casting sand to form a mold 50, and the mold 50 is formed. Including the casting steps (steps S8 and S9) in which the molten metal is charged, the model 20 has a hole 21 formed in a portion where the curved tube 10 is arranged, and the model data creation step is 3D of the curved tube 10. This is a step of creating 3D data of the model 20 including the hole portion 21 having a shape that matches the data. Thereby, the shape of the hole 21 in which the curved pipe 10 is arranged can be determined based on the 3D data (curved pipe data 101) of the curved pipe 10 actually arranged. Therefore, the compatibility between the hole 21 of the actual model 20 and the actual curved tube 10 can be considerably improved, and the relative positions of the model 20 and the curved tube 10 can be made considerably less likely to shift. As a result, the misalignment of the curved pipe in the mold 1 can be suppressed. Further, since it is only necessary to add the step of acquiring the curved tube data, the increase in cost can be suppressed as much as possible.

Further, in the present embodiment, before the curved pipe data creation step, a curved pipe manufacturing step (step S1) of bending a straight metal pipe to obtain the curved pipe 10 is further included. When the curved pipe 10 is obtained by bending a straight metal pipe, the degree of curvature of the curved pipe 10 is likely to differ from one to another. If the model 20 is created using the curved pipe data 101 of the curved pipe 10 obtained by the bending process, the shape of the hole 21 can be adjusted according to such a difference in the individual shapes. .. Therefore, the misalignment of the curved tube 10 in the mold 1 can be suppressed more effectively.

Further, in the present embodiment, before the curved pipe data creation step, a curved pipe connecting step (step S2) for connecting the intermediate portions of the curved pipe 10 is further included, and the curved pipe data creating step includes a plurality of connected. It is a step of creating the curved tube data 101 by 3D scanning the curved tube group 100 composed of the curved tube 10, and in the model data creating step, the curved tube group 100 can be arranged by using the 3D data of the curved tube group 100. This is a step of creating model data 200 so that the hole portion 21 is formed. As a result, since the intermediate portions of the curved pipes 10 are connected to each other to form the curved pipe group 100, it is possible to suppress the pitch shift between the curved pipes 10. Further, the shape of the hole 21 in which the curved pipe group 100 is arranged becomes complicated as compared with the case where one curved pipe 10 is arranged. On the other hand, if the 3D data of the curved tube group 100 is acquired and the shape of the hole 21 is determined based on the 3D data (curved tube data 101), the hole 21 of the actual model 20 can be obtained. The compatibility with the actual curved tube group 100 can be improved. As a result, the misalignment of the curved tube 10 in the mold 1 can be suppressed more effectively.

(Other embodiments)
The technique disclosed herein is not limited to the above-described embodiment, and can be substituted as long as it does not deviate from the gist of the claims.

For example, in the above-described embodiment, the case where the curved tube group 100 formed by connecting the intermediate portions of the plurality of curved tubes 10 with the connecting tool 13 is 3D-scanned to obtain the curved tube data 101 is targeted. Not limited to this, when only one curved pipe 10 is cast into the mold 1 or when one curved pipe 10 independent of the curved pipe group 100 is cast into the mold 1, the curved pipe 10 is used. The curved tube data regarding the curved tube 10 may be obtained by 3D scanning.

Further, in the above-described embodiment, the curved tube 10 is obtained by manually bending a straight metal tube. Not limited to this, a straight metal tube may be machined to obtain a curved tube 10. Further, not only when the curved pipe 10 obtained by processing a straight metal pipe is cast into the mold 1, but also when the curved pipe 10 manufactured so as to form a curved portion in advance is cast into the mold 1. If included, it may be included in the scope of this disclosure.

The above embodiments are merely examples, and the scope of the present disclosure should not be construed in a limited manner. The scope of the present disclosure is defined by the scope of claims, and all modifications and changes belonging to the equivalent scope of the scope of claims are within the scope of the present disclosure.

The technique disclosed herein is useful in casting a metal curved tube having at least one curved portion to manufacture a hot press molding die.

1 Hot press molding die 10 Curved tube 11 1st curved part (curved part)
12 Second curved part (curved part)
13 Connector 20 model (mold shape member)
21 Hole 50 Mold 100 Curved tube group 101 Curved tube data (3D data of curved tube, 3D data of curved tube group)
200 model data (3D model data)

Claims (3)

A method for manufacturing a die for hot press molding, in which a metal curved tube having at least one curved portion is cast to manufacture a die.
A curved tube data creation step of 3D scanning the curved tube to create 3D data of the curved tube,
A model data creation process for creating 3D data of a model imitating the mold using the 3D data of the curved tube, and
A model creation process for creating the model using the 3D data of the model, and
A curved pipe arranging step of arranging the actual curved pipe on the created model, and
After the curved pipe arranging step, the model is filled with casting sand to form a mold, and a casting step of pouring molten metal into the mold is included.
In the model, a hole is formed in a portion where the curved pipe is arranged.
The hot press molding die is characterized in that the model data creating step is a step of creating 3D data of the model including 3D data of a hole having a shape matching the 3D data of the curved tube. Manufacturing method. In the method for manufacturing a hot press molding die according to claim 1,
A method for manufacturing a hot press molding die, which further comprises a curved pipe manufacturing step of bending a straight metal pipe to obtain the curved pipe before the curved pipe data creating step. In the method for manufacturing a hot press molding die according to claim 1 or 2.
There are multiple curved tubes,
Prior to the curved pipe data creation step, a curved pipe connecting step of connecting the intermediate portions of the curved pipes with a connecting tool is further included.
The curved tube data creation step is a step of creating 3D data of the curved tube group by 3D scanning a curved tube group composed of the plurality of curved tubes connected.
The model data creation step is a step of creating 3D data of the model by using the 3D data of the curved tube group so that the hole matching the shape of the curved tube group is formed. A characteristic method for manufacturing a hot press molding die.

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