JP5901493B2 - Hot press molding method and mold - Google Patents

Description

  The present invention relates to a hot press forming method and a mold for press forming a heated steel plate.

  As a workpiece formed by the hot press forming method, for example, there is a reinforcing member that reinforces the body of an automobile. This reinforcing member has a high-strength portion that secures a vehicle interior space and a low-strength that absorbs an impact on the body. May need both departments. Although it is conceivable that the portion for securing the interior space and the portion for absorbing the impact on the vehicle body are configured as separate members, it takes time to manufacture the reinforcing member.

  Therefore, conventionally, after the first heating means for heating the part to be high strength of the work and the second heating means for heating the whole work, after heating the part to be high strength of the work by the first heating means, A hot press molding method is known in which a high-strength portion and a low-strength portion are integrally formed in a molded workpiece by press-molding the entire workpiece by second heating means (for example, a patent) Reference 1).

JP 2009-95869 A

However, the above conventional configuration requires a first heating means for heating a portion of the work to be high in strength separately from the second heating means for heating the whole work, so that the heating equipment becomes large. In addition, since heat transfer occurs in the workpiece during heating or conveyance of the steel plate, it is difficult to control the temperature distribution.
This invention is made | formed in view of the situation mentioned above, and it aims at providing the hot press molding method and metal mold | die which can give an intensity | strength difference to a workpiece | work with simple structure.

In order to achieve the above object, the present invention provides a hot press molding method in which a heated work is press-molded by a mold, and a coolant is passed between the mold and the work to cool the work. In addition, a protrusion projecting from the molding surface of the mold is provided at the boundary between the portion to be high strength and the portion to be low strength of the workpiece, so that the degree of adhesion between the mold and the workpiece is high strength. said mold at a portion to have higher than adhesiveness between the work you characterized.
According to the above configuration, the degree of adhesion between the mold and the workpiece at the boundary between the portion to be high strength and the portion to be low strength of the workpiece is higher than the degree of adhesion between the mold and the workpiece at the portion to be high strength. For this reason, it is possible to suppress the refrigerant from flowing to the work of the portion to be reduced in strength by the portion having improved adhesion.

The present invention provides a hot press molding method in which a heated work is press-molded with a mold and a coolant is allowed to flow between the mold and the work to cool the work. A convex portion that makes the degree of adhesion between the mold and the workpiece at the boundary between the portion to be reduced and the portion to be low strength higher than the degree of adhesion between the mold and the workpiece at the portion to be high strength. It is provided at the boundary.
According to the said structure, it can suppress that a refrigerant | coolant flows into the workpiece | work of the part made into low intensity | strength by the simple structure of providing a convex part in the boundary of a workpiece | work.

The said structure WHEREIN: You may provide the said convex part in the said metal mold | die integrally or separately.
The said structure WHEREIN: You may arrange | position the member which improves adhesiveness between the said metal mold | die and the said workpiece | work in the said boundary.
According to the said structure, it can suppress that a refrigerant | coolant flows into the workpiece | work of the part made into low intensity | strength by the simple structure of arrange | positioning the member which improves adhesiveness between the metal mold | die and a workpiece | work in a boundary.

Further, the present invention provides a mold for press-molding a heated workpiece and cooling the workpiece by flowing a coolant between the workpiece and a portion for increasing the strength and a portion for decreasing the strength. Protrusions protruding from the molding surface of the mold are provided at the boundary between the mold and the work so that the degree of adhesion between the mold and the work is higher than the degree of adhesion between the mold and the work at the portion where the strength is increased. It is characterized by that.
According to the above configuration, the degree of adhesion between the mold and the workpiece at the boundary between the portion to be high strength and the portion to be low strength of the workpiece is higher than the degree of adhesion between the mold and the workpiece at the portion to be high strength. For this reason, it is possible to suppress the refrigerant from flowing to the work of the portion to be reduced in strength by the portion having improved adhesion.

In the above configuration, an upper mold and a lower mold may be provided, and the convex portion may be provided on at least one of the upper mold and the lower mold.
According to the said structure, it can suppress that a refrigerant | coolant flows into the workpiece | work of the part made low intensity | strength by the simple structure of providing a convex part in at least one of an upper mold | type and a lower mold | type.

The said structure WHEREIN: An upper mold | type and a lower mold | type may be provided, and the said convex part may be provided by shifting a position in both the said upper mold | type and a lower mold | type.
According to the said structure, it can suppress that a refrigerant | coolant flows into the workpiece | work of the part made into low intensity | strength with the simple structure of providing a convex part by shifting a position to both an upper mold | type and a lower mold | type.

According to the present invention, the degree of adhesion between the mold and the workpiece at the boundary between the portion to be high strength and the portion to be low strength of the workpiece is higher than the adhesion between the die and the workpiece at the portion to be high strength. Therefore, the portion where the adhesion is enhanced can suppress the flow of the refrigerant to the workpiece of the portion to be reduced in strength, and the workpiece can be provided with a difference in strength with a simple configuration.
In addition, with a simple configuration in which a convex portion is provided at the boundary of the workpiece, it is possible to suppress the flow of the refrigerant to the workpiece at the portion to be reduced in strength, and to make a difference in strength between the workpieces.
In addition, with a simple configuration in which a member that enhances adhesion between the mold and the workpiece at the boundary is disposed, it is possible to suppress the flow of the refrigerant to the portion of the workpiece to be reduced in strength, and to make a difference in strength between the workpieces. .

In addition, with a simple configuration in which a convex portion is provided on at least one of the upper die and the lower die, it is possible to suppress the flow of the refrigerant to the work in the portion to be reduced in strength, and to make a difference in strength between the work.
Further, with a simple configuration in which the convex portions are provided by shifting the positions of both the upper die and the lower die, it is possible to suppress the flow of the refrigerant to the work in the portion to be reduced in strength, and to make a difference in strength between the work. Moreover, it can prevent that the boundary of a workpiece | work becomes thin.

It is sectional drawing which shows typically the press molding apparatus provided with the metal mold | die which concerns on embodiment of this invention. It is sectional drawing which shows typically the press-molding apparatus clamped. It is a figure which shows the workpiece | work shape | molded with a metal mold | die, (A) is a perspective view, (B) is a top view. It is a figure which shows the IV-IV cross section of FIG. It is a perspective view which shows the workpiece | work shape | molded with the metal mold | die. It is a perspective view which shows the workpiece | work formed with the metal mold | die which concerns on the modification of this invention. It is a perspective view which shows the workpiece | work formed with the metal mold | die which concerns on the modification of this invention. It is sectional drawing which shows typically the metal mold | die which concerns on the modification of this invention. It is sectional drawing which shows typically the metal mold | die which concerns on the modification of this invention. It is sectional drawing which shows typically the metal mold | die which concerns on the modification of this invention. It is sectional drawing which shows typically the metal mold | die which concerns on the modification of this invention. It is sectional drawing which shows typically the metal mold | die which concerns on the modification of this invention. It is sectional drawing which shows typically the hot press molding method which concerns on the modification of this invention. It is sectional drawing which shows typically the hot press molding method which concerns on the modification of this invention. It is sectional drawing which shows typically the hot press molding method which concerns on the modification of this invention.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 is a cross-sectional view schematically showing a press molding apparatus provided with a mold according to the present embodiment. FIG. 2 is a cross-sectional view schematically showing a press-molding apparatus that has been clamped. In FIGS. 1 and 2 and the drawings shown below, the gap between the workpiece and the mold is emphasized.
The press molding apparatus 1 includes a mold 10 and a blank holder 2 that holds a workpiece 20 to be molded by the mold 10. The mold 10 includes a lower mold 11 disposed on the installation surface S and an upper mold 12 disposed above the lower mold 11. The lower mold 11 is a fixed convex mold, and the upper mold 12 is a movable concave mold. The lower mold 11 and the upper mold 12 are provided with a refrigerant path 13 through which a refrigerant (for example, a liquid such as water) flows, and a plurality of supply ports communicating with the refrigerant path 13 on the molding surfaces of the lower mold 11 and the upper mold 12 14 is provided, and the refrigerant is directly supplied to the workpiece 20 from these supply ports 14.

A work pressing surface 15 is formed on the periphery of the upper mold 12, and the blank holder 2 is provided so as to face the work pressing surface 15.
A cushion pin 3 that pushes the blank holder 2 through the installation surface S from below is connected to the blank holder 2, and the cushion pin 3 is supported by a hydraulic cylinder (not shown). Always pushes up the blank holder 2.

  When the workpiece 20 is hot press-molded, as shown in FIG. 1, the workpiece 20 heated to a predetermined temperature (temperature at which quenching can be performed) is placed on the lower mold 11 and the blank holder 2, and the upper mold 12 is Lower toward the lower mold 11. When the work pressing surface 15 of the upper mold 12 hits the work 20, the work 20 is sandwiched and pulled by the upper mold 12 and the blank holder 2 to prevent the work 20 from being wrinkled. Further, as shown in FIG. 2, when the upper mold 12 is lowered, the mold 10 is clamped and the work 20 is squeezed along the shape between the lower mold 11 and the upper mold 12. Then, the work 20 is cooled (quenched) by supplying the coolant directly to the work 20 from the supply port 14. When the workpiece 20 is cooled, the upper mold 12 is raised, the workpiece 20 is taken out, and the hot press molding process is completed.

FIGS. 3A and 3B are views showing a workpiece 20 to be molded by the mold 10, FIG. 3A is a perspective view, and FIG. 3B is a plan view.
The workpiece 20 is formed from a steel plate in a hat shape by hot press forming, and has flanges 21 at both ends in the width direction. The workpiece 20 of the present embodiment is used, for example, as a reinforcing member that reinforces the body of an automobile, and is formed using a high-strength steel plate that has high strength. The workpiece 20 as a reinforcing member includes a high-strength portion 23 having a high strength that secures a vehicle interior space, and a low-low strength that absorbs an impact on the vehicle body, with a boundary 22 positioned substantially in the center of the flange 21 in the extending direction. And a strength portion 24. Note that the position of the boundary 22 can be changed as appropriate.

  As a method of integrally forming the high-strength portion and the low-strength portion, the high-strength portion is heated by the first heating means, and then the entire workpiece is heated and press-molded by the second heating means, thereby achieving high strength. The part to be heated is heated to a quenchable temperature, the part to be made low strength is heated so as not to reach the quenchable temperature, and the high strength part and the low strength part are integrally formed in the molded workpiece. There is a press molding method. In this method, apart from the second heating means for heating the entire steel plate, the first heating means for heating the portion of the steel plate that has high strength is required, so that the heating equipment becomes large. In addition, since heat transfer occurs in the workpiece during heating or conveyance of the workpiece, it is difficult to control the temperature distribution.

In addition, a molded workpiece is provided by providing a heater or refrigerant path in the mold to increase the degree of heat removal (cooling) of the high-strength part and cooling (quenching) the high-strength part. There is a hot press molding method in which a high-strength portion and a low-strength portion are integrally formed. In this method, since the workpiece is cooled by indirect heat removal by contact with the mold, the cooling takes time, and the cycle time for manufacturing the workpiece becomes long.
As a cooling method, there is a direct water cooling method in which a refrigerant is directly supplied to a workpiece from a plurality of supply ports, but in a conventional direct water cooling method in which a supply port is provided in a portion to be cooled, it is difficult to control the flow of the refrigerant, As a result, the quenching position cannot be controlled.
Hereinafter, a configuration for integrally forming the high-strength portion 23 and the low-strength portion 24 according to the present embodiment will be described in detail.

4 is a view showing a cross section taken along the line IV-IV in FIG. FIG. 5 is a perspective view showing the workpiece 20 formed by the mold 10.
In the present embodiment, as shown in FIG. 4, the refrigerant path 13 and the supply port 14 are provided only on the high-strength portion 23 side of the workpiece 20, and the upper mold 12 has a straight line corresponding to the boundary 22 of the workpiece 20. The convex part (bead) 16 extended in the shape is formed. The convex portion 16 is formed in a protruding shape that protrudes toward the lower mold 11, and the height of the convex portion 16 is such that when the refrigerant is supplied into the clamped mold 10, The height is set so as not to enter.

  When the mold 10 configured in this way is used, when the mold 10 is clamped, the degree of adhesion between the mold 10 and the workpiece 20 at the boundary 22 increases, and when the refrigerant is supplied from the supply port 14, the refrigerant Does not flow to the low-strength portion 24 but flows only to the high-strength portion 23. Thereby, since only the high-strength part 23 can be rapidly cooled, only the high-strength part 23 can be quenched and the strength of the high-strength part 23 can be made higher than that of the low-strength part 24. As shown in FIG. 5, a mark 25 of the convex portion 16 remains on the molded workpiece 20 at a position corresponding to the convex portion 16.

In the present embodiment, the supply port 14 is provided on one side of the workpiece 20 (high strength portion 23 for increasing strength), and the upper mold 12 of the boundary 22 between one side and the other (low strength portion 24 for decreasing strength). The workpiece 20 having both the high-strength portion 23 having high strength and the low-strength portion 24 having low strength can be easily formed by a simple configuration in which the convex portion 16 is formed. Moreover, since it is not necessary to provide a heating device in the mold 10, the configuration of the mold 10 is simplified. Further, unlike the prior art, no heating means dedicated to the high-strength portion is required, so that the heating device does not become large.
In the present embodiment, the low-strength portion 24 is not directly cooled by the refrigerant, but when the quenching is completed and the temperature of the workpiece 20 is lowered to a temperature at which the shape of the workpiece 20 does not change, the workpiece 20 is removed from the mold 10. Therefore, the cycle time for manufacturing the workpiece 20 does not become extremely long.

  As described above, according to the present embodiment, the degree of adhesion between the mold 10 and the workpiece 20 at the boundary 22 between the high-strength portion 23 and the low-strength portion 24 of the workpiece 20 is determined. 10 and the workpiece 20 are configured to have a higher degree of adhesion, and more specifically, the convex portion 16 is provided on the mold 10 at the boundary 22. With this configuration, it is possible to suppress the refrigerant from flowing into the low-strength portion 24 by the convex portion 16, and to make a difference in strength between the workpieces 20 with a simple configuration.

However, the above embodiment is an aspect of the present invention, and it is needless to say that the embodiment can be appropriately changed without departing from the gist of the present invention.
For example, in the above embodiment, the heated workpiece 20 is arranged in the lower mold 11. However, a heating means may be provided in the mold 10, the workpiece 20 may be arranged after being arranged in the lower mold 11, and then press-molded. .
Moreover, in the said embodiment, in order to shorten cooling time, although the refrigerant path 13 and the supply port 14 were provided in the both sides of the lower mold | type 11 and the upper mold | type 12, it provided in one of the lower mold | type 11 and the upper mold | type 12. Also good.

In the above embodiment, the height of the convex portion 16 is set to such a height that the refrigerant does not enter the low strength portion 24 side when the refrigerant is supplied into the mold 10 that has been clamped. It may be a height that allows a small amount of refrigerant to enter the low-strength portion 24 so that the low-strength portion 24 is not quenched.
Moreover, in the said embodiment, although the height of the convex part 16 was set to such an extent that the trace 25 remains in the workpiece | work 20 pushed by the said convex part 16, the workpiece | work 20 of the part pushed by the convex part 16 is set. It may be set to such an extent that the trace 25 does not remain after returning by elastic deformation.

  Moreover, in the said embodiment, although the linear convex part 16 was provided in the upper mold | type 12, the whole shape of the convex part 16 is not limited to this. For example, as shown in FIG. 6, an intermittent linear protrusion (not shown) may be provided so that an intermittent linear boundary 22 (trace 125) is formed. In the example of FIG. 6, the convex portions are provided so that the traces 125 are intermittently formed along two parallel straight lines forming the boundary 22. However, the present invention is not limited to this. For example, a convex part may be provided intermittently along one straight line. Further, as shown in FIG. 7, a plurality of dot-like convex portions (not shown) may be provided so that a plurality of dot-like boundaries 22 (traces 225) are formed.

Moreover, in the said embodiment, although the convex part 16 was formed in cross-sectional rectangular shape, the cross-sectional shape of the convex part 16 is not limited to this, For example, as shown in FIG. You may form circularly.
Moreover, in the said embodiment, although the convex part 16 was provided in the upper mold | type 12, you may provide in the lower mold | type 11, and you may provide in both the lower mold | type 11 and the upper mold | type 12. When providing a convex part in both the lower mold | type 11 and the upper mold | type 12, you may match the position of the convex part of the upper mold | type 12 and the lower mold | type 11, and it prevents that the boundary 22 of the workpiece | work 20 becomes thin. Therefore, as shown in FIG. 9, the convex portion 416 may be provided by being shifted to the upper mold 12 and the lower mold 11.

Moreover, in the said embodiment, although the convex part was protrusion shape, the cross-sectional shape of a convex part is not limited to this, For example, as shown in FIG.10 and FIG.11, a convex part is step shape. There may be. In the example of FIG. 10, stepped protrusions 516 are provided on both the upper mold 12 and the lower mold 11, and in the example of FIG. 11, stepped protrusions 616 are provided on the upper mold 12. A convex portion may be provided on at least one of the lower mold 11. For example, although not illustrated, a stepped convex portion may be provided on the lower mold 11.
Further, in FIG. 10, the stepped convex portion 516 is provided so that the thickness is the same between the high-strength portion 23 and the low-strength portion 24, but the thickness is high between the high-strength portion 23 and the low-strength portion 24. You may provide a step-shaped convex part so that it may differ. In the example of FIG. 12, the step-like convex portion 716 is provided so that the high-strength portion 23 side is thick, but the step-like convex portion may be provided so that the low-strength portion 24 side is thick.
In addition, the code | symbol 325 in FIG. 8, the code | symbol 425 in FIG. 9, the code | symbol 525 in FIG. 10, the code | symbol 625 in FIG. 11, and the code | symbol 725 in FIG. It is a trace formed by.

Moreover, in the said embodiment, although the member (convex part) which raises the adhesiveness of the metal mold | die 10 and the workpiece | work 20 in the boundary 22 was provided in the metal mold | die 10, in view of the maintainability of the metal mold | die 10, the said member ( For example, as shown in FIGS. 13 and 14, the convex portion may be provided on the workpiece 20 side. The shape of the convex portion is not particularly limited, and a convex portion 26 having a substantially rectangular cross section is formed at a position corresponding to the boundary 22 on the upper surface of the workpiece 20, as in the example of FIG. A convex portion 126 having a substantially semicircular cross section may be formed at a position corresponding to the boundary 22 on the upper surface of the workpiece 20 by forming 20 in a substantially wave shape.
Moreover, the convex part does not need to be integrated with the workpiece 20, and a separate convex part 226 may be provided at a position corresponding to the boundary 22 of the workpiece 20, as shown in FIG. The material of the separate convex portion 226 may be the same as that of the workpiece 20 or may be a heat-resistant material such as silicon. Thereby, since it is not necessary to process a workpiece | work itself, manufacture of a workpiece | work becomes easy compared with the case where a convex part is provided in a workpiece | work.
Note that the overall shape of the convex portion provided on the workpiece 20 side is not limited to a linear shape, and may be an intermittent shape as shown in FIGS. 6 and 7.

Moreover, in the said embodiment, although the workpiece | work was shape | molded by the cross-sectional hat shape, the shaping | molding shape of a workpiece | work is not limited to this.
Moreover, in the said embodiment, although water was used as a refrigerant | coolant, a refrigerant | coolant may be not only a liquid but gas.
Moreover, although the said embodiment demonstrated the workpiece | work as a reinforcement member which reinforces the vehicle body of a motor vehicle, this invention is applicable to the various workpiece | work which has a high intensity | strength part and a low intensity | strength part.

DESCRIPTION OF SYMBOLS 1 Press molding apparatus 10 Mold 11 Lower mold 12 Upper mold 16,116 ... 716 Convex part (member which improves adhesiveness)
20 Work 22 Boundary 23 High-strength part (high-strength part)
24 Low strength part (part to make low strength)
26, 126, 226 Convex

Claims (6)

In the hot press molding method in which a heated work is press-molded by a mold and a coolant is passed between the mold and the work to cool the work.
Protruding portions projecting from the molding surface of the mold are provided at the boundary between the portion to be high strength and the portion to be low strength of the workpiece to increase the degree of adhesion between the mold and the workpiece. A hot press molding method characterized in that the degree of adhesion between the mold and the workpiece at a part is higher. In the hot press molding method in which a heated work is press-molded by a mold and a coolant is passed between the mold and the work to cool the work.
The degree of adhesion between the mold and the workpiece at the boundary between the high strength portion and the low strength portion of the workpiece is set higher than the adhesion between the mold and the workpiece at the high strength portion. A hot press molding method , wherein a convex portion is provided at the boundary of the workpiece . The hot press molding method according to claim 1, wherein the convex portion is provided integrally with the mold or separately . In the mold for cooling the workpiece by pressing a heated workpiece and flowing a coolant between the workpiece and the workpiece,
Protruding portions projecting from the molding surface of the mold are provided at the boundary between the portion to be high strength and the portion to be low strength of the workpiece to increase the degree of adhesion between the mold and the workpiece. A mold characterized by having a higher degree of adhesion between the mold and the workpiece at a portion. With upper and lower molds,
The mold according to claim 4, wherein the convex portion is provided at a position corresponding to the boundary of at least one of the upper mold and the lower mold. With upper and lower molds,
6. The mold according to claim 5, wherein the convex portions are provided by shifting the positions of both the upper mold and the lower mold.

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