JP2013059777A - Hot press working method and hot press working device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a hot press working method and a hot press working device, which can facilitate post-processing after hot press to a high strength steel, and can prevent the generation of delayed fracture.SOLUTION: The hot press working method includes a hot press process (STEP-1) and a punching process (STEP-2), wherein the hot press process (STEP-1) includes a pre-punching process (STEP-1-3, 4) to preliminarily punch out, by a die 11 and a punch 12, a punched part 6c to be removed in the post-processing, and the punching process (STEP-2) includes a main punching process (STEP-2-2) to actually punch out, by a punch 21, the punched part 6c preliminarily punched in the pre-punching process.

Description

  The present invention relates to a technique of a hot press processing method and a hot press processing apparatus.

In recent years, in the field of the automobile industry and the like, in order to further improve the performance (fuel consumption, safety, etc.), the body has been made lighter and more rigid, and the use of high-strength steel sheets has increased. Yes.
High-strength steel sheets are high-strength, but have the property of being difficult to perform additional machining after forming, so that products made of high-strength steel sheets formed by hot pressing are post-processed. Various techniques have been studied.

A technique for post-processing a product made of a high-strength steel sheet formed by hot pressing is disclosed in, for example, Patent Document 1 shown below and is publicly known.
In the prior art disclosed in Patent Document 1, a split groove is formed in the intermediate molded body by providing a protrusion on a clamping surface of a molding die for clamping a material in a hot press process. By forming the split groove at the time of hot pressing, it becomes possible to perform the process of easily folding the intermediate molded body in the split groove even after the hot pressing step, and unnecessary portions and the like are removed. Post-processing can be easily performed.

  There is also known a hot press method in which an intermediate formed body is formed by a hot press process and at the same time, a punching process is performed in a high temperature state (low tensile strength of the material).

JP 2010-94698 A

In the prior art disclosed in Patent Document 1, it is possible to easily post-process an intermediate molded body formed by a hot press process after the hot press process.
However, when post-processing a high-strength steel sheet, there is a problem that delayed fracture occurs at a site where stress or the like is applied, but the conventional technique disclosed in Patent Document 1 does not consider the occurrence of delayed fracture. There was a problem.

  In addition, in the hot press method in which the intermediate formed body is formed by the hot press process and at the same time, the punching process is performed in a high temperature state (low tensile strength of the material), a mechanism for performing the punching process, Since it is necessary to equip a press die (die, punch, etc.) with a mechanism for discharging scrap, there is also a problem that the configuration of the press die is complicated and large.

  The present invention has been made in view of such current problems, and facilitates post-processing after hot pressing on high-strength steel and can prevent occurrence of delayed fracture and hot pressing. The object is to provide a press working apparatus.

  The problem to be solved by the present invention is as described above. Next, means for solving the problem will be described.

  That is, in claim 1, there is provided a hot press processing method having a hot press step and a punching step, wherein the hot press step temporarily removes a punched portion, which is a portion to be removed by post-processing, by a die and a punch. The punching process includes a permanent punching process in which the punched part temporarily punched in the temporary punching process is punched by a punch.

  In Claim 2, the said hot press process and the said punching process are performed in a different place.

  According to a third aspect of the present invention, the temporary punching in the temporary punching step forms a V-shaped groove by the die and punch to form the punched portion.

  According to a fourth aspect of the present invention, after the main punching step, the diameter of an opening formed in a portion where the punched portion is removed is increased by the punch.

  In Claim 5, it is a hot press processing apparatus used for the hot press processing method which has a hot press process and a punching process, Comprising: The press apparatus for performing the said hot press process is provided, The said press apparatus is a die | dye. The die and the punch have a substantially annular projecting portion for forming a V-shaped groove portion surrounding the punched portion and temporarily punching the punched portion in the hot pressing step. .

  According to a sixth aspect of the present invention, a punch device having a punch for pressing the punched portion is further provided, and the punched portion is pressed by the punch to remove the punched portion.

  In claim 7, the outer diameter dimension of the punch is made larger than the inner diameter dimension of the opening formed in the portion where the punched portion is removed, and the punch is pushed into the opening. The diameter of the opening is increased.

  As effects of the present invention, the following effects can be obtained.

  According to the first aspect, post-processing after hot press molding can be performed while preventing the occurrence of delayed fracture.

  In claim 2, the hot press working process can be simplified.

  According to the third aspect, post-processing after hot press molding can be performed while preventing the occurrence of delayed fracture.

  According to the fourth aspect of the present invention, the occurrence of delayed fracture can be prevented.

  According to the fifth aspect, post-processing after hot press molding can be performed while preventing the occurrence of delayed fracture.

  In Claim 6, a hot press processing apparatus can be made into a simple structure.

  According to the seventh aspect of the present invention, post-processing after hot press molding can be performed while preventing the occurrence of delayed fracture.

The schematic diagram which shows the whole structure of the hot press processing apparatus which concerns on one Embodiment of this invention. The schematic diagram which shows the press apparatus of the hot press processing apparatus which concerns on one Embodiment of this invention. The schematic diagram which shows the projection part formed in the die | dye and punch of a press apparatus, (a) Cross-sectional schematic diagram, (b) Plane schematic diagram. The schematic diagram which shows the punch apparatus of the hot press processing apparatus which concerns on one Embodiment of this invention. The flowchart which shows the hot press processing method which concerns on one Embodiment of this invention. The schematic diagram which shows the processing condition (STEP-1-1) by the hot press processing method using the hot press processing apparatus which concerns on one Embodiment of this invention. The schematic diagram which shows the processing condition (STEP-1-2) by the hot press processing method using the hot press processing apparatus which concerns on one Embodiment of this invention. The schematic diagram which shows the processing condition (STEP-1-3-4) by the hot press processing method using the hot press processing apparatus which concerns on one Embodiment of this invention. The partial expansion schematic diagram which shows the temporary extraction | drawer condition of the extraction part in an intermediate molded object. The schematic diagram which shows the processing condition (STEP-2-1) by the hot press processing method using the hot press processing apparatus which concerns on one Embodiment of this invention. The schematic diagram which shows the processing condition (STEP-2-2-3) by the hot press processing method using the hot press processing apparatus which concerns on one Embodiment of this invention. The partial expansion schematic diagram which shows the dimensional difference of a punch and a punching part. The partial expansion schematic diagram which shows the diameter expansion situation of the hole by a punch. The schematic diagram which shows the intermediate molded object after this punching, and the product after diameter expansion.

Next, embodiments of the invention will be described.
First, an overall configuration of a hot press working apparatus according to an embodiment of the present invention will be described with reference to FIGS.
As shown in FIG. 1, a hot press processing apparatus 1 according to an embodiment of the present invention is a processing apparatus used in a hot press processing method according to an embodiment of the present invention, and an apparatus for executing a hot press process. And a punch device 20 which is a device for executing the punching process.

That is, in the hot press processing apparatus 1, the press apparatus 10 and the punch apparatus 20 are provided separately. In the hot press processing method using the hot press processing apparatus 1, the hot press process and the punching process are performed at different locations and The configuration is performed at the timing.
For this reason, in the hot press processing apparatus 1, it is possible to configure each of the apparatuses 10 and 20 more simply than when the conventional press apparatus 10 has a function corresponding to the punch apparatus 20. ing.

  As shown in FIG. 2, the press device 10 is a part for performing hot pressing on a blank 5 (refer to FIG. 6) as a product base, and includes a die 11, a punch 12, a blank holder 13, a cushion 14, and a cushion. Pins 15 and 15 are provided.

  The die 11 is a part that forms a concave mold, and includes a first member 11a on which a mold surface 11b parallel to the pressing direction is formed and a second member 11c that forms a mold surface 11d orthogonal to the pressing direction. Yes. Further, the second member 11c is surrounded by the first member 11a, and the inside of the first member 11a can be displaced.

  The die 11 is supported by a displacement device (not shown) and is configured to be displaced in the vertical direction (press direction). As a displacement device for supporting the die 11, a hydraulic cylinder or the like can be adopted.

Further, as shown in FIGS. 2 and 3A and 3B, a ring-shaped protrusion 11e is formed on the mold surface 11d facing the punch 12 of the second member 11c.
The protrusion 11e is formed corresponding to the position, size, shape, etc. of the hole to be formed by post-processing on the blank 5, and has a pointed shape having a pointed portion 11f.

As shown in FIG. 2, the punch 12 is a portion constituting a convex mold, and a mold surface 12a parallel to the pressing direction and a mold surface 12b orthogonal to the pressing direction are formed.
The punch 12 is supported by a holder 16.
The holder 16 is fixed to a frame or the like (not shown) of the press device 10 and cannot be displaced, and the punch 12 supported by the holder 16 is also undisplaceable.

Further, as shown in FIGS. 2 and 3A and 3B, a ring-shaped protrusion 12c is formed on the mold surface 12b facing the mold surface 11d of the die 11.
The protrusion 12c is formed corresponding to the position, size, shape, etc. of the hole to be formed by post-processing on the blank 5, and has a pointed shape having a pointed portion 12d.

  As shown in FIG. 3A, the protrusion 11e formed on the die 11 and the protrusion 12c formed on the punch 12 are arranged so as to face each other while matching the arrangement positions in plan view. Yes.

As shown in FIG. 2, the blank holder 13 is a part for holding the blank 5 in cooperation with the die 11 (more specifically, the first member 11 a), and is disposed around the punch 12.
Cushion pins 15 and 15 are in contact with the lower surface of the blank holder 13 in the pressing direction.
The cushion 14 is in contact with the lower ends of the cushion pins 15.

The cushion 14 is an elastic member configured to be able to expand and contract in the pressing direction, and is fixed to a non-displaceable base portion 17 fixed to a frame or the like (not shown) of the pressing device 10.
Therefore, when the cushion pins 15 and 15 are displaced downward in the pressing direction, the cushion 14 applies an upward reaction force opposite to the pressing direction to the cushion pins 15 and 15 by the elastic force of the cushion 14. can do.

  And it is set as the structure which ensures the clamping force required in order to clamp the blank 5 with the blank holder 13 and the die | dye 11, by pressing the blank holder 13 with the upward reaction force provided to the cushion pins 15.15. .

  As shown in FIG. 4, the punch device 20 is a part for punching the intermediate molded body 6 (see FIG. 8) formed through the hot pressing process. The holding part 23 and the like are provided.

  The punch 21 is a part for pressing a part to be removed of the intermediate molded body 6 set on the table 22, and is connected to a reciprocally displaceable cylinder provided in a hydraulic device (not shown).

  The punch 21 includes a first pressing surface 21a that is a surface orthogonal to the displacement direction of the punch 21 (a lower end surface of the punch 21) and a surface parallel to the displacement direction of the punch 21 (an outer peripheral surface of the punch 21). A second pressing surface 21b is formed.

  The pedestal 22 is formed with a convex portion 22a corresponding to the concave shape of the intermediate molded body 6 and a hole 22b serving as a passage for dropping a member removed by punching.

  When the pressing part 23 presses the portion to be removed of the intermediate molded body 6 placed on the table 22 with the punch 21, the intermediate molded body 6 may be displaced or excessive deformation may occur. The intermediate molded body 6 is pressed against the cradle 22 during the punching process so that the intermediate molded body 6 follows the convex portion 22a of the cradle 22 during the punching process.

Next, the hot press processing method using the hot press processing apparatus 1 which concerns on one Embodiment of this invention is demonstrated using FIGS.
As shown in FIG. 5, in the hot press working method using the hot press working apparatus 1 according to one embodiment of the present invention, first, the hot press process (STEP-1) using the press apparatus 10 is executed. In addition, after the hot press process (STEP-1) is completed, the blanking process (STEP-2) is executed to complete a series of hot press processes for the blank 5.

That is, in the hot press processing method according to an embodiment of the present invention, the hot press step (STEP-1) and the punching step (STEP-2) are performed at different locations (that is, the press device 10 and the punch device 20). It is what is said.
With such a configuration, the hot pressing process can be simplified.

Moreover, the hot press processing apparatus 1 which concerns on one Embodiment of this invention is further provided with the punch apparatus 20 which has the punch 21, and presses the extraction part 6c with the punch 21, and removes the extraction part 6c.
With such a configuration, the hot press working apparatus can be simplified.

First, a hot press process (STEP-1) is demonstrated.
As shown in FIGS. 5 and 6, the blank 5 heated to a predetermined temperature is disposed at a predetermined position on the blank holder 13 in the press device 10 (STEP-1-1).

  Then, as shown in FIGS. 5 and 7, the die 11 is lowered, and the blank 5 is sandwiched between the die 11 and the blank holder 13 (STEP-1-2).

  Next, as shown in FIGS. 5 and 8, the die 11 is further lowered, and the blank 5 is caused to flow into a space shaped like a product surrounded by the die 11 and the punch 12 (STEP 1-3).

Then, the blank 5 hot-pressed into a predetermined shape is cooled and quenched to form an intermediate molded body 6 having a substantially hat-like shape (STEP 1-4).
At this time, as shown in FIG. 9, a ring-shaped groove 6a having a substantially V-shaped cross-sectional shape is engraved on the upper surface of the intermediate molded body 6 against which the protrusion 11e is pressed, and the protrusion 12c is On the lower surface of the pressed blank 5, a ring-shaped groove 6b having a substantially V-shaped cross section is formed.

And as a part partitioned by each groove part 6a * 6b, the extraction part 6c which is a part which should be removed by post-processing is formed.
The process for forming the punched portion 6c in the hot pressing process is referred to as “temporary punching”.
Here, in order to facilitate removal of the punched portion 6c by post-processing, the protrusions 11e and 12c are formed so that the distance between the deepest portions 6d and 6e of the grooves 6a and 6b is as small as possible. And the separation distance between the die 11 and the punch 12 are set (see FIG. 12).

That is, in the hot press working method according to an embodiment of the present invention, in the temporary punching process (STEP-1-3, 4), the V-shaped groove portions 6a and 6b are formed by the die 11 and the punch 12. Thus, the punched portion 6c is formed.
With such a configuration, post-processing after hot press molding can be performed while preventing the occurrence of delayed fracture.

Next, the punching process (STEP-2) will be described.
As shown in FIGS. 5 and 10, the intermediate molded body 6 that has been hot-pressed in the press device 10 and molded into a predetermined shape, and that has been temporarily punched, is placed at a predetermined position of the punch device 20 (on the table 22. It arrange | positions to the convex part 22a) (STEP-2-1).

Then, as shown in FIGS. 5 and 11, the punch 21 is lowered and the punched portion 6c is pressed by the punch 21 to remove the punched portion 6c of the intermediate molded body 6 (STEP-2-2).
The process of removing the punched portion 6c in this punching process is referred to as “main punching”.
Here, the intermediate molded body 6 from which the punched portion 6c has been removed is distinguished and displayed as the intermediate molded body 7 after the punching process.
The removed punched portion 6c falls through the hole 22b and is collected at a predetermined portion (a portion for collecting scrap) (not shown).
Further, in the hot press processing method using the hot press processing apparatus 1, the temperature of the intermediate molded bodies 6 and 7 is compared with the temperature during the hot press at the time when the punch apparatus 20 performs the processing (when the main punching is performed). And it is low.

  A hole 7a is formed in a portion where the punched portion 6c is removed from the intermediate molded body 7 after the main punching. A residual stress F1 acting in the direction of reducing the diameter of the hole 7a exists around the broken portion 7b in the hole 7a.

  Then, by further lowering the punch 21, the diameter of the hole 7a of the intermediate molded body 7 is increased by the punch 21 (STEP-2-3).

As shown in FIG. 12, the outer diameter dimension φA of the punch 21 is larger than the outer diameter dimension φB of the punched portion 6c and smaller than the maximum outer diameter dimension φC of the groove portions 6a and 6b.
Therefore, as shown in FIG. 13, when the punch 21 is further lowered, the punch 21 is pushed into the hole 7a while the first pressing surface 21a of the punch 21 presses the fracture portion 7b substantially downward.
For this reason, when the punch 21 is pushed into the hole 7a, the second pressing surface 21b presses the fractured portion 7b of the hole 7a in the direction of expanding the diameter outward in the horizontal direction.
At this time, stress F2 is applied to the fractured portion 7b in the hole 7a in the direction of expanding the diameter of the hole 7a.

That is, at this time, since the stress F2 opposite to the residual stress F1 is applied to the fracture portion 7b, the residual stress F1 is reduced and the delayed fracture around the hole 7a is prevented.
The stress F2 applied to the fracture portion 7b applied by the second pressing surface 21b can be adjusted by changing the outer diameter of the punch 21, so that the outer diameter dimension φA of the punch 21 is optimized (residual stress). By suspending F1 and stress F2, the occurrence of delayed fracture can be reliably prevented.

That is, in the hot press working method according to an embodiment of the present invention, the opening formed in the punched portion 6c by the punch 21 after the main punching step (STEP-2-2) (STEP-2-3). The diameter of the hole 7a is increased.
With such a configuration, the occurrence of delayed fracture can be prevented.

In the hot press working apparatus 1 according to the embodiment of the present invention, the outer diameter φA of the punch 21 is set to the inner diameter of the hole 7a formed by removing the punched portion 6c (that is, the punched portion 6c). The diameter of the hole 7a is increased by pushing the punch 21 into the hole 7a.
With such a configuration, post-processing after hot press molding can be performed while preventing the occurrence of delayed fracture.

  And in the hot press processing method using the hot press processing apparatus 1 which concerns on one Embodiment of this invention, by removing the residual stress F1 which causes a delayed fracture in this way, as shown in FIG. The product 8 in which the occurrence of delayed fracture around the hole 8a is suppressed can be generated.

  That is, the hot press processing method according to an embodiment of the present invention includes a hot press process (STEP-1) and a punching process (STEP-2), and the hot press process (STEP-1) A temporary punching process (STEP-1-3, 4) is provided, in which the punched portion 6c, which is a part to be removed by post-processing, is temporarily punched by the die 11 and the punch 12; This is provided with a main punching step (STEP-2-2) in which the punched portion 6c is temporarily punched by the punch 21 in the step (STEP-1-3, 4).

Moreover, the hot press processing apparatus 1 which concerns on one Embodiment of this invention is used for the hot press processing method which has a hot press process and a punching process, Comprising: The press apparatus 10 for performing a hot press process is provided. The pressing device 10 includes a die 11 and a punch 12, and the die 11 and the punch 12 form V-shaped grooves 6a and 6b surrounding the punched portion 6c and temporarily punch the punched portion 6c in a hot press process. For this purpose, the projections 11e and 12c have a substantially annular shape.
With such a configuration, post-processing after hot press molding can be performed while preventing the occurrence of delayed fracture.

DESCRIPTION OF SYMBOLS 1 Hot press processing apparatus 10 Press apparatus 11 Die 12 Punch 13 Blank holder 20 Punch apparatus 21 Punch

Claims (7)

A hot press processing method having a hot press process and a punching process,
The hot pressing step includes
A temporary punching process for temporarily punching a punched portion, which is a part to be removed by post-processing, with a die and a punch,
The punching process includes
Comprising a main punching step of punching the punched portion temporarily punched in the temporary punching step by a punch;
The hot press processing method characterized by the above-mentioned. The hot pressing step and the punching step are
Done in different places,
The hot press processing method according to claim 1. Temporary punching in the temporary punching step is
The V-shaped groove is formed by the die and punch to form the punched portion.
The hot press processing method according to claim 1 or 2, wherein After the main punching process,
With the punch, the diameter of the opening formed at the site where the punched portion is removed is increased.
The hot press processing method according to any one of claims 1 to 3, wherein: A hot press processing apparatus used in a hot press processing method having a hot press process and a punching process,
A press device for performing the hot pressing step;
The press device includes a die and a punch,
The die and the punch have a substantially annular projection for forming a V-shaped groove portion surrounding the punched portion and temporarily punching the punched portion in the hot pressing step.
The hot press processing apparatus characterized by the above-mentioned. Furthermore, a punch device having a punch for pressing the punched portion is provided,
Pressing the punched portion with the punch to remove the punched portion;
The hot press processing apparatus according to claim 5. The outer diameter dimension of the punch,
Increasing the inner diameter dimension of the opening formed in the portion where the extracted portion is removed,
Expanding the diameter of the opening by pushing the punch into the opening;
The hot press processing apparatus according to claim 5 or 6, characterized in that

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