Method for manufacturing hot-pressed products and hot-press forming device

Abstract

To suppress occurrence of cracks or wrinkles in a hot press product, and further, to suppress deterioration of dimensional accuracy of the hot press product, thereby obtaining high productivity.SOLUTION: According to a method of the present invention, a hot press product is obtained by hot press molding a heated material 20A to be molded by use of an upper die and a lower die having refrigerant flow paths 15, 16 therein and a blank holder 14. The upper die and the lower die are caused to approach each other, and in the state that a gap G between an outer periphery holding surface 22 of the upper die and a top face of the blank holder 14 is maintained at a prescribed interval larger than a thickness of the material 20A to be molded, the material 20A to be molded is drawn between the upper die and the lower die. Before arriving at a molding bottom dead point, a drawn-up part 24 on an outer periphery of the material 20A to be molded gets out of the gap G between the outer periphery holding surface 22 of the upper die and the top face of the blank holder 14. When arriving at the molding bottom point, the drawn-up part 24 on the outer periphery of the material 20A to be molded does not remain in the gap G between the outer periphery holding surface 22 of the upper die and a top face of the blank holder 14, and is sandwiched between the upper die and the lower die.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] The present invention relates to a method for manufacturing a hot-pressed product and a hot-press forming apparatus. [Background technology]

[0002] In recent years, in order to improve automobile fuel efficiency, there has been a demand for further weight reduction in automobile frame parts such as pillars, side sills, and roof rails, and hot press forming using thin ultra-high tensile steel sheets has been widely used.

[0003] Hot press forming, also known as hot stamping, hot pressing, or hot forming, is a technique in which a workpiece (blank) heated to a high temperature is press-formed, and then rapidly cooled at the bottom dead center in a mold cooled by a refrigerant to remove heat and then quenched to obtain a high-strength formed product.

[0004] Products that have been hot-pressed (quenched) have poor ductility and are difficult to press-form in subsequent processes. For products with complex shapes that cannot be formed by hot-press bending alone, forming using drawing is performed in the hot press.

[0005] However, in hot press drawing, if the workpiece is tightly clamped between the die (die face) and blank holder, as in cold press drawing, the clamped portion of the workpiece is rapidly cooled by the heat dissipation from the refrigerant-cooled mold. This prevents material flow during drawing, potentially resulting in localized thickness reduction. This increases the likelihood of cracks occurring in the workpiece, making it difficult to press-form complex shapes. On the other hand, in hot press forming, in order to maintain formability and strength, it is desirable to rapidly cool the workpiece, held at bottom dead center, using the refrigerant-cooled mold.

[0006] Patent Document 1 describes a drawing method in hot pressing in which the upper part of the blank holder (blank holder) is held by an absorber and the lower part of the blank holder is held by an elastic member, the material to be formed is formed while maintaining a gap between the protruding surface (die face surface) and the blank holder surface during the press forming process, and after reaching bottom dead center, the protruding surface and the blank holder are brought close to each other to sandwich the material to be formed. [Prior art documents] [Patent documents]

[0007] [Patent Document 1] Japanese Patent Application Laid-Open No. 2011-147970 Summary of the Invention [Problem to be solved by the invention]

[0008] In the method of Patent Document 1, hot pressing is started with the blank holder held by an elastic member installed between the bottom surface of the blank holder (blank holder) and the top surface of the support part of the lower die, and an absorber controls the gap between the die face surface of the upper die (the bottom surface of the protrusion) and the top surface of the blank holder. Because the spring constant of the absorber is greater than the spring constant of the elastic member, the absorber maintains the gap during hot press forming (while the blank holder is descending), and at the bottom dead center, the absorber contracts, eliminating the gap. In other words, the die face surface of the mold for hot pressing requires gap control to maintain the temperature of the workpiece during the forming process, and uniform surface contact is required at the bottom dead center to rapidly cool the workpiece.

[0009] However, with this type of gap control method using upper and lower pressure sources (absorbers and elastic members), it is difficult to adjust the pressure balance depending on the shape of the workpiece during the forming process, which can cause the gap between the die and the blank holder to vary, making the formed product more susceptible to cracks or wrinkles.

[0010] In addition, it is extremely difficult to adjust the height to make the gap between the punch and the blank holder uniform at the bottom dead center, making it difficult to achieve uniform surface contact with the parts of the workpiece on the die face that change in thickness, which may result in problems such as reduced cooling performance and uneven cooling.

[0011] Furthermore, the reduced cooling performance of the workpiece increases the time required for hardening the workpiece, preventing the time the workpiece is held in the mold from being shortened, resulting in a decrease in productivity.

[0012] Furthermore, if the workpiece is cooled unevenly, the hardness after quenching may vary, which may result in a decrease in the dimensional accuracy of the hot-pressed product.

[0013] Furthermore, the absorber used to ensure the gap requires a large gas spring or the like, which leads to an increase in size and complexity of the die structure, resulting in a very expensive hot press forming device.

[0014] Therefore, the present invention aims to provide a method for manufacturing a hot-pressed product and a hot press forming apparatus that can prevent cracks or wrinkles from occurring in the hot-pressed product, prevent a decrease in the dimensional accuracy of the hot-pressed product, and achieve high productivity. [Means for solving the problem]

[0015] A method for manufacturing a hot-pressed product according to one aspect of the present invention is a method for manufacturing a hot-pressed product by hot-press-forming a heated workpiece using upper and lower dies having internal coolant channels and a blank holder. The upper and lower dies are brought close to each other, and the workpiece is drawn between the upper and lower dies while maintaining a gap between the outer peripheral pressing surface of the upper die and the top surface of the blank holder at a predetermined distance greater than the thickness of the workpiece. Before reaching the bottom dead center of forming, the drawn portion of the outer periphery of the workpiece escapes from the gap between the outer peripheral pressing surface of the upper die and the top surface of the blank holder. When the bottom dead center of forming is reached, the drawn portion of the outer periphery of the workpiece is sandwiched between the upper and lower dies without remaining in the gap between the outer peripheral pressing surface of the upper die and the top surface of the blank holder.

[0016] A hot press-forming apparatus according to one aspect of the present invention includes an upper die and a lower die having a coolant flow path therein, and a blank holder. The upper die and the lower die are brought close together, and the workpiece is drawn between the upper die and the lower die while a gap between the outer peripheral pressing surface of the upper die and the upper surface of the blank holder is maintained at a predetermined distance greater than the thickness of the workpiece. Before reaching the bottom dead center of forming, the drawn portion of the outer periphery of the workpiece escapes from the gap between the outer peripheral pressing surface of the upper die and the upper surface of the blank holder. When the bottom dead center of forming is reached, the drawn portion of the outer periphery of the workpiece is sandwiched between the upper die and the lower die without remaining in the gap between the outer peripheral pressing surface of the upper die and the upper surface of the blank holder. [Effects of the Invention]

[0017] According to one aspect of the present invention, a method for manufacturing a hot-pressed product and a hot-press forming apparatus can prevent cracks or wrinkles from occurring in the hot-pressed product, and can also prevent a decrease in the dimensional accuracy of the hot-pressed product, thereby achieving high productivity. [Brief explanation of the drawings]

[0018] [Figure 1] FIG. 2 is a perspective view showing a lower die in the hot press forming apparatus. [Figure 2] FIG. 2 is a perspective view showing a lower die and a blank holder in the hot press forming apparatus. [Figure 3] FIG. 2 is a schematic cross-sectional view of a die of a hot press forming apparatus. [Figure 4A] 1 is a diagram showing the processing steps of a method for manufacturing a hot-pressed product. FIG. [Figure 4B] 1 is a diagram showing the processing steps of a method for manufacturing a hot-pressed product. FIG. [Figure 4C] 1 is a diagram showing the processing steps of a method for manufacturing a hot-pressed product. FIG. [Figure 4D] 1 is a diagram showing the processing steps of a method for manufacturing a hot-pressed product. FIG. [Figure 5A] FIG. 10 is a diagram showing the length of the workpiece and the cross-sectional shape of the mold when the drawing depth is deep. [Figure 5B]FIG. 10 is a diagram showing the shape of a workpiece when the drawing depth is deep. [Figure 6A] FIG. 10 is a diagram showing the length of the workpiece and the cross-sectional shape of the mold when the drawing depth is shallow. [Figure 6B] FIG. 10 is a diagram showing the shape of a workpiece when the drawing depth is shallow. [Figure 7A] FIG. 10 is a diagram showing the length of the workpiece and the cross-sectional shape of the mold when the drawn up portion is long. [Figure 7B] FIG. 10 is a diagram showing the shape of a workpiece when the drawn up portion is long. [Figure 8A] FIG. 10 is a diagram showing the length of the workpiece and the cross-sectional shape of the mold when the drawn up portion is short. [Figure 8B] FIG. 10 is a diagram showing the shape of a workpiece when the drawn up portion is short. [Figure 9A] FIG. 10 is a diagram showing the length of the workpiece and the cross-sectional shape of the mold when there is a vertical wall on the outer periphery. [Figure 9B] FIG. 10 is a diagram showing the shape of a workpiece when there is a vertical wall on the outer periphery. DETAILED DESCRIPTION OF THE INVENTION

[0019] Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings.

[0020] In the following, in explaining the embodiments, a hot press forming method will be described in which an upper die attached to the drive side of a hot press forming device is lowered by press driving, and the heated workpiece is press-formed in an upward direction by a lower punch attached to the fixed side of the hot press device.

[0021] (Configuration of hot press forming equipment) As shown in FIGS. 1 to 3 , a mold 11 of a hot press-forming apparatus 10 has a die 12 as an upper mold, a punch 13 as a lower mold, and a blank holder 14 for clamping, and drawing can be performed using a hot press. The basic configuration of the mold 11 is similar to that of a cold press-forming apparatus, but the die 12 and punch 13 are provided with a plurality of water-cooled pipes (refrigerant channels) 15, 16 through which a refrigerant such as water flows to cool the mold 11 heated by hot press-forming (see FIG. 3 ). The blank holder 14 may also be provided with water-cooled pipes 15, 16, but the blank holder 14 of this embodiment is not provided with water-cooled pipes 15, 16. Furthermore, the blank holder 14 is not made of a typical cast metal but is made of a steel plate.

[0022] The blank holder 14 is held in place by multiple gas springs (elastic support parts) 18 attached to the punch holder 17 (see Figure 1). Fixed (non-movable) gap management blocks (gap maintenance parts) 21, each approximately 70 mm in diameter, are attached to the top surface of the blank holder 14 using bolts or the like at intervals of 300 to 400 mm. Depending on the attachment position, either cylindrical gap management blocks 21 or rectangular pillar-shaped gap management blocks 21 are arranged (see Figure 2).

[0023] The centers of the gas springs 18 and the gap management blocks 21 are positioned at approximately the same location. That is, the gas springs 18 and the gap management blocks 21 are arranged concentrically and overlap each other in a plan view. For this reason, like the gap management blocks 21, the gas springs 18 are attached to the punch holder 17 at intervals of 300 mm to 400 mm using bolts or the like. By arranging the gas springs 18 and the gap management blocks 21 in this manner, when the gap management block 21 is pressed down by the die 12, the blank holder 14 is pressed down in a balanced manner. For this reason, the set gap G (see Figures 4B and 4C) is always obtained around the entire circumference of the workpiece 20A during the forming process.

[0024] In this embodiment, an example is shown in which the gap management block 21 is attached to the upper surface of the blank holder 14, but it may also be attached to the outer periphery (seat surface 23) of the die face 22 of the die 12. Furthermore, the gap management block 21 may be formed by being cast integrally with the die 12 and then being machined to provide a flush surface. In short, any method is acceptable as long as the gap management block 21 can accurately obtain the gap G between the die face 22 of the die 12 and the upper surface of the blank holder 14. As described above, the gap management block 21 is attached to the upper surface of the blank holder 14 because it is easy to perform final adjustment of the gap G inside the mold 11 using a shim (spacer) or the like.

[0025] The die face 22 of the die 12 is provided with a seat (recess) 23 at a position where the gap control block 21 abuts during press forming. Furthermore, no water-cooling pipes 15, 16 are provided near the die face 22 of the die 12. The gap G between the die face 22 of the die 12 and the upper surface of the blank holder 14 is adjusted by the height of the gap control block 21 and is set to be the thickness of the workpiece 20A + 0.5 mm during hot press forming. This gap G is not necessarily the thickness of the workpiece 20A + 0.5 mm. A gap G of the thickness of the workpiece 20A + 0.5 mm to 2.0 mm is assumed, and is determined by the material and thickness of the workpiece 20A, the shape of the workpiece 20B, the profile (cross-sectional shape) of the mold 11, and the like.

[0026] (Hot press forming method) First, a workpiece 20A is prepared, which has been subjected to external processing, including the creation of pilot pin guide holes, etc., by ordinary cold working. The workpiece 20A is made of a thin steel sheet for hot pressing, such as an aluminum-plated steel sheet or a zinc-plated steel sheet, to which manganese, boron, or the like, which is an element that improves hardenability, has been added.

[0027] The workpiece 20A heated in the heating furnace is placed on the blank holder 14 in the mold 11 at the top dead center of the hot press using a transport jaw (transport robot) or the like (not shown) (see Figure 4A).

[0028] At this time, the workpiece 20A is positioned by a positioning pin (not shown) and a nest (not shown).

[0029] When the hot press is driven, the die 12 descends, and the upper surface of the gap management block 21 attached to the blank holder 14 abuts against the gap management block abutment portion (seat surface 23) provided on the die face surface 22 (see Figure 4B).

[0030] As the hot press machine is driven to further lower the die 12, a seat 23 provided on the die face 22 presses against a gap control block 21 attached to the blank holder 14, thereby pushing down the blank holder 14. At this time, the gas spring 18 is also pressed down and compressed in conjunction with the blank holder 14. As a result, the workpiece 20A is hot press-formed (draw-formed) by the die 12 and punch 13, with the gap G between the die face 22 of the die 12 and the top surface of the blank holder 14 remaining at the thickness of the workpiece 20A + 0.5 mm (see FIG. 4C ).

[0031] Furthermore, as the die 12 is further lowered by driving the hot press machine, the heated workpiece 20A is hot press-formed (drawing-formed) by the die 12 and punch 13 while being loosely clamped between the die face 22 and the blank holder 14.

[0032] Furthermore, as the die 12 further descends due to the driving of the hot press, the drawn portion 24 on the outer periphery of the workpiece 20A is pulled into the inside of the die 12 by the punch 13 approximately 5 mm before the bottom dead center, and comes out from above the blank holder 14 (see Figure 4D).

[0033] In order for the drawn portion 24 on the outer periphery of the workpiece 20A, which was on the blank holder 14 until approximately 5 mm before the bottom dead center, to come off the blank holder 14, the shape (outer shape) and drawing depth of the workpiece 20A, as well as the cross-sectional shape of the punch 13, are important.

[0034] For example, when forming shapes of the same width (or diameter), the outer shape of the blank 20A to be formed in a product with a deep drawing depth will be larger than the outer shape of the blank 20A to be formed in a product with a shallow drawing depth (see FIGS. 5A and 5B, 6A and 6B). Also, the clamping allowance C1 of the blank 20A to be formed in a product with a deep drawing depth will be larger than the clamping allowance C2 of the blank 20A to be formed in a product with a shallow drawing depth (see FIGS. 5A and 5B, 6A and 6B).

[0035] On the same product, the outer shape of the portion with a deep drawing depth will be larger than the outer shape of the portion with a shallow drawing depth (see Figs. 5A and 6A). Also, on the same product, the clamping allowance C1 of the portion with a deep drawing depth will be larger than the clamping allowance C2 of the portion with a shallow drawing depth (see Figs. 5A and 6A).

[0036] When the length (width) of the drawn upward portion 24 is long, the clamping allowance C3 is greater than the clamping allowance C4 when the length (width) of the drawn upward portion 24 is short (see FIGS. 7A and 7B, 8A and 8B).

[0037] When the drawn portion 24 on the outer periphery of the workpiece 20A is not simply shaped like a hat cross section but has a vertical wall 25, the clamping allowance C5 is greater than the clamping allowance C4 when the drawn portion 24 is simply shaped like a hat cross section (see Figures 9A and 9B, 8A and 8B).

[0038] As mentioned above, the external shape of the workpiece 20A varies depending on the drawing depth, the length and shape of the drawn portion 24, etc., but it is also determined by tests, simulations, etc., including adjustments to the cross-sectional shape of the punch 13, such as the rounded shape of the corners of the punch 13. Of course, the external shape also varies depending on the type (steel type) of the workpiece 20A used, so various tests are conducted using actual components, and the results are reflected in the simulations to determine the external shape of the workpiece 20A.

[0039] The effects of this embodiment will be described below.

[0040] (1) The method for manufacturing a hot-pressed product according to this embodiment is a method for manufacturing a hot-pressed product by hot-press-forming a heated workpiece 20A using a die and punch 13 having internal water-cooling pipes 15, 16, and a blank holder 14. The die 12 and punch 13 are brought close to each other, and the workpiece 20A is drawn between the die 12 and the punch 13 while maintaining a gap G between the die face 22 of the die 12 and the upper surface of the blank holder 14 at a predetermined distance greater than the thickness of the workpiece 20A. Before reaching the bottom dead center of forming, the drawn portion 24 on the outer periphery of the workpiece 20A escapes from the gap G between the die face 22 of the die 12 and the upper surface of the blank holder 14. When the bottom dead center of forming is reached, the drawn portion 24 on the outer periphery of the workpiece 20A is sandwiched between the die 12 and the punch 13 without remaining in the gap G between the die face 22 of the die 12 and the upper surface of the blank holder 14.

[0041] (2) The gap G between the die face surface 22 of the die 12 and the upper surface of the blank holder 14 is maintained at a predetermined distance using a gap management block 21 provided between the die face surface 22 of the die 12 and the upper surface of the blank holder 14.

[0042] (3) The hot press-forming apparatus 10 includes a die 12 and a punch 13 having water-cooling pipes 15 and 16 therein, and a blank holder 14. The die 12 and the punch 13 are brought close to each other, and the workpiece 20A is drawn between the die 12 and the punch 13 while a gap G between the die face 22 of the die 12 and the upper surface of the blank holder 14 is maintained at a predetermined distance greater than the thickness of the workpiece 20A. Before the workpiece 20A reaches the bottom dead center of forming, a drawn portion 24 on the outer periphery of the workpiece 20A escapes from the gap G between the die face 22 of the die 12 and the upper surface of the blank holder 14. When the workpiece 20A reaches the bottom dead center of forming, the drawn portion 24 on the outer periphery of the workpiece 20A does not remain in the gap G between the die face 22 of the die 12 and the upper surface of the blank holder 14, but is sandwiched between the die 12 and the punch 13.

[0043] (4) The hot press forming apparatus 10 is provided with a gap management block 21 that is disposed between the die face surface 22 of the die 12 and the upper surface of the blank holder 14 and that maintains the gap G between the die face surface 22 of the die 12 and the upper surface of the blank holder 14 at a predetermined distance.

[0044] (5) The gap control block 21 is provided on at least one of the die face 22 of the die 12 and the upper surface of the blank holder 14 .

[0045] (6) The hot press-forming apparatus 10 includes a gas spring 18 that elastically supports the blank holder 14. The gap control block 21 and the gas spring 18 are positioned so as to overlap each other in a plan view.

[0046] (7) The water cooling pipes 15 and 16 are not provided in the vicinity of the die face 22 of the die 12 and in the blank holder 14 .

[0047] In this embodiment, the gap G between the die face 22 and the blank holder 14 is constant from the time the workpiece 20A is clamped between the die 12 (die face 22) and the blank holder 14 until the hot press forming is completed (bottom dead center of the hot press). Then, just before bottom dead center, the drawn portion 24 of the workpiece 20A comes out of the gap G, and ultimately the drawn portion 24 of the workpiece 20A does not remain on the blank holder 14. Therefore, compared to a hot press forming method in which the workpiece 20A is tightly clamped between the die face 22 and the blank holder 14 at bottom dead center, there is no sudden reduction in thickness, and therefore cracks are suppressed even in complex deep-drawn products.

[0048] In this embodiment, the period up to just before bottom dead point is drawing, and the period from just before bottom dead point to holding at bottom dead point (forming completion) is forming. The timing at which the drawn portion 24 of the workpiece 20A comes out of the gap G between the die face 22 and the blank holder 14 just before bottom dead point is just before bottom dead point of hot press forming, and since the forming period is short, the occurrence of wrinkles is also suppressed.

[0049] In summary, in this embodiment, at bottom dead center, the workpiece 20B has already come out of the blank holder 14. Therefore, when the workpiece 20B is held at bottom dead center, it is possible to rapidly cool the workpiece 20B by uniform surface contact only with the die 12 and punch 13 cooled by the refrigerant, and it is possible to prevent a decrease in cooling performance.

[0050] The improved cooling performance shortens the quenching time of the workpiece 20A, shortening the time the workpiece 20A is held in the mold, improving productivity. In addition, there is no uneven cooling in each part of the workpiece 20B, and there is no variation in the amount of bainite generated during the austenite-to-martensitic transformation, so there is little variation in the quenched hardness of the workpiece 20B, improving the dimensional accuracy of the hot-pressed product.

[0051] In this embodiment, a fixed gap control block 21 (typically made of S45C material) can be used to ensure a gap G between the blank holder 14 and the die face 22 that holds the workpiece 20A during hot press forming of the workpiece 20B. This allows the structure of the die 11 to be simplified.

[0052] Furthermore, the seat surface 23 of the die face 22 that abuts against the gap management block 21 can be machined to a flat surface when the upper die is made, and the upper die 12 does not have a complicated structure.

[0053] In addition, in this embodiment, the blank holder 14 does not need to bottom out even at the bottom dead center, so the rigidity of the blank holder 14 can be reduced and the conventional cast structure can be changed to a steel plate structure.

[0054] These various structural changes also enable the die 11 to be made smaller.

[0055] Furthermore, in this embodiment, the gap G between the die face 22 and the blank holder 14 is always kept constant during forming. Therefore, the die face 22 and the blank holder 14 do not become very hot, and there is no need to use cooling devices such as water-cooled pipes 15, 16 near the die face 22 or inside the blank holder 14 (see FIG. 3).

[0056] In this embodiment, the water-cooled pipes 15, 16 are not provided in the area near the die face 22 of the die 12 or in the blank holder 14. Therefore, just before the bottom dead center, the drawn portion 24 of the workpiece 20A can be rapidly cooled through the gap G by the die 12 and punch 13, which are cooled by the refrigerant.

[0057] As a result of the above, a more inexpensive hot press forming apparatus 10 can be obtained.

[0058] The hot press product manufacturing method and hot press forming apparatus of the present invention have been described using the above-mentioned embodiment as an example, but they are not limited to this embodiment and various other embodiments can be adopted within the scope of the gist of the present invention.

[0059] As described above, the embodiment has been described as a hot press-forming method in which the upper die attached to the drive side of the hot press-forming apparatus is lowered by press driving, and the heated workpiece is press-formed in an upward direction by the lower punch attached to the fixed side of the hot press apparatus. However, the upper die and lower punch may be reversed. In other words, a hot press-forming method in which press-forming is performed in a downward direction by the upper punch and lower die may also be used.

[0060] In the above-mentioned hot press forming method, when hot pressing begins, the workpiece may be held down in advance by a leading pad and punch to prevent wrinkles on the top surface of the product, and then processing with the die may begin. Even in this case, the workpiece is released from the blank holder, so a locking mechanism to prevent buckling of the workpiece is not required, and a more inexpensive hot press forming apparatus can be obtained. [Explanation of symbols]

[0061] 10. Hot press forming equipment 11 Mold 12 Die 13 Punch 14 Blank holder 15 Water-cooled pipe (refrigerant flow path) 16 Water-cooled pipe (refrigerant flow path) 17 Punch holder 18 Gas spring 20A Material to be formed 20B Molded product 21 Gap management block (gap maintenance section) 22 Die face (periphery pressing surface) 23 Seat (recess) 24. Squeezing up section 25 Vertical Wall C1~C5 Clamping allowance G Gap

Claims

1. A method for manufacturing a hot-pressed product by hot-press-forming a heated workpiece using upper and lower dies having coolant flow paths therein and a blank holder, comprising: The upper die and the lower die are brought close to each other, and the workpiece is draw-formed between the upper die and the lower die while maintaining a gap between an outer peripheral pressing surface of the upper die and an upper surface of the blank holder at a predetermined distance greater than the thickness of the workpiece; Before the workpiece reaches the bottom dead point of forming, the drawn portion of the outer periphery of the workpiece escapes from the gap between the outer periphery pressing surface of the upper die and the upper surface of the blank holder, When the workpiece reaches the bottom dead point of forming, the drawn portion of the outer periphery of the workpiece does not remain in the gap between the outer periphery pressing surface of the upper die and the upper surface of the blank holder, but is sandwiched between the outer periphery pressing surface of the upper die and the lower die. Manufacturing method for hot pressed products.

2. a gap between the outer peripheral pressing surface of the upper die and the upper surface of the blank holder is maintained at the predetermined distance by using a gap maintaining portion provided between the outer peripheral pressing surface of the upper die and the upper surface of the blank holder; A method for producing the hot-pressed product according to claim 1.

3. The apparatus includes an upper mold and a lower mold each having a coolant flow path therein, and a blank holder, the upper die and the lower die are brought close to each other, and the workpiece is draw-formed between the upper die and the lower die while a gap between an outer peripheral pressing surface of the upper die and an upper surface of the blank holder is maintained at a predetermined distance greater than the thickness of the workpiece; Before the workpiece reaches the bottom dead point of forming, the drawn portion of the outer periphery of the workpiece escapes from the gap between the outer periphery pressing surface of the upper die and the upper surface of the blank holder, When the workpiece reaches the bottom dead point of forming, the drawn portion of the outer periphery of the workpiece does not remain in the gap between the outer periphery pressing surface of the upper die and the upper surface of the blank holder, but is sandwiched between the outer periphery pressing surface of the upper die and the lower die. Hot press forming equipment.

4. a gap maintaining portion provided between the outer peripheral pressing surface of the upper die and the upper surface of the blank holder, the gap maintaining portion maintaining the gap between the outer peripheral pressing surface of the upper die and the upper surface of the blank holder at the predetermined distance; The hot press forming apparatus according to claim 3 .

5. The gap maintaining portion is provided on at least one of an outer peripheral pressing surface of the upper die and an upper surface of the blank holder. The hot press forming apparatus according to claim 4.

6. an elastic support portion that elastically supports the blank holder; The gap maintaining portion and the elastic support portion are positioned so as to overlap each other in a plan view. The hot press forming apparatus according to claim 4 or 5.

7. The coolant flow path is not provided in a portion near the outer peripheral pressing surface of the upper die and in the blank holder. The hot press forming apparatus according to any one of claims 4 to 6.

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