JP2022185340A - Hot press product manufacturing method, and hot press molding device - Google Patents

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 The present invention relates to a hot press product manufacturing method and a hot press forming apparatus.

In recent years, in order to improve the fuel efficiency of automobiles, further weight reduction of automobile frame parts such as pillars, side sills, and roof rails is desired, and hot press forming using thin ultra-high-strength steel sheets is often used. .

Hot press molding is also called hot stamping, hot pressing, or hot forming. In this hot press forming, a material to be formed (blank material) heated to a high temperature is press-molded, and then rapidly cooled in a mold cooled by a refrigerant at the bottom dead center to remove heat and quenched to achieve high strength. It is a technique to obtain a molded product of

Products after hot press forming (after quenching) lack ductility and are difficult to press form in the post-process. Forming using drawing is performed in the hot press.

However, in draw forming in hot press, if the material to be formed is firmly clamped between a die (die face) and a blank holder as in draw forming in cold press, the clamped part of the material to be formed will be It is rapidly cooled by heat removal by the die cooled by the coolant, and local thinning (thickness reduction) may occur without material flow during draw forming. For this reason, the possibility of cracks occurring in the material to be formed increases, making it difficult to press-form a complicated shape. On the other hand, in hot press forming, in order to maintain formability and strength, it is actually desirable to rapidly cool the molded article held at the bottom dead center using a mold cooled by a coolant.

As a draw forming method in hot press, in Patent Document 1, the upper part of the wrinkle holding part (blank holder) is held by an absorber, the lower part of the wrinkle holding part is held by an elastic member, and the protruding surface (die face surface) and the wrinkle-holding surface is maintained, and after reaching the bottom dead center, the protruding part and the wrinkle-holding part are brought close to each other, and the material is sandwiched. Have been described.

JP 2011-147970 A

In the method of Patent Document 1, hot pressing is started while the blank holder is held by an elastic member provided between the lower surface of the blank holder (wrinkle holding portion) and the upper surface of the support portion of the lower mold. The gap between the die face surface (lower surface of the protrusion) and the upper surface of the blank holder is managed by an absorber. That is, since the spring constant of the absorber is greater than the spring constant of the elastic member, the gap is maintained by the absorber during hot press forming (while the blank holder is descending), and at the bottom dead center, the absorber shrinks to create the gap. is configured to eliminate In other words, the die face of the mold for hot pressing requires a gap control to maintain the temperature of the molded material during the molding process, and at the bottom dead center, uniform surface contact is required to rapidly cool the molded product. is required.

However, with such a gap management method using upper and lower pressure sources (absorbers and elastic members), it is difficult to adjust the pressure balance due to the shape of the material to be molded during the molding process, and the gap between the die and the blank holder varies. Cracks or wrinkles are likely to occur in the molded product.

In addition, it is extremely difficult to adjust the height to make the gap between the punch and the blank holder uniform against the die at the bottom dead center, and it is difficult to make uniform surface contact with the thickness change part of the molded product on the die face surface. , there is a possibility that problems such as a decrease in cooling performance and uneven cooling may occur.

In addition, due to the deterioration of the cooling performance of the molded product, the quenching time of the molded product becomes longer, which prevents the shortening of the retention time of the molded product in the mold, resulting in a decrease in productivity.

In addition, if the molded product is cooled unevenly, the quenching hardness may vary, and the dimensional accuracy of the hot pressed product may decrease.

Furthermore, the absorber that secures the gap must use a large gas spring or the like, which leads to an increase in the size and complexity of the mold structure, resulting in a very expensive hot press molding apparatus.

Accordingly, the present invention provides a hot press product capable of suppressing the occurrence of cracks or wrinkles in the hot press product, suppressing the deterioration of the dimensional accuracy of the hot press product, and obtaining high productivity. An object of the present invention is to provide a manufacturing method and a hot press forming apparatus.

A method for manufacturing a hot press product according to one aspect of the present invention comprises hot press molding a heated workpiece using an upper mold and a lower mold having coolant flow paths therein and a blank holder. It is a method of manufacturing a hot press product by The upper mold and the lower mold are brought closer to each other, and the material to be molded is placed between the upper mold and the lower mold while maintaining the gap between the outer peripheral pressing surface of the upper mold and the upper surface of the blank holder at a predetermined distance larger than the thickness of the material to be molded. It draw-forms between molds. Before reaching the molding bottom dead center, the drawn-up portion of the outer circumference of the material to be formed is removed from the gap between the outer circumference pressing surface of the upper die and the upper surface of the blank holder. When the bottom dead center of molding is reached, the drawn up part of the outer periphery of the material to be formed does not remain in the gap between the outer periphery pressing surface of the upper die and the upper surface of the blank holder, and is sandwiched between the upper die and the lower die. .

A hot press molding apparatus according to an aspect of the present invention includes an upper mold and a lower mold having coolant channels therein, and a blank holder. The upper die and the lower die are brought closer to each other, and the workpiece is placed between the upper die and the gap between the outer peripheral pressing surface of the upper die and the upper surface of the blank holder. Draw forming is performed between the lower die and the lower die. Before reaching the molding bottom dead center, the drawn-up portion of the outer circumference of the material to be formed is removed from the gap between the outer circumference pressing surface of the upper die and the upper surface of the blank holder. When the bottom dead center of molding is reached, the drawn up part of the outer periphery of the material to be formed does not remain in the gap between the outer periphery pressing surface of the upper die and the upper surface of the blank holder, and is sandwiched between the upper die and the lower die. .

According to the hot press product manufacturing method and the hot press forming apparatus according to one aspect of the present invention, the occurrence of cracks or wrinkles in the hot press product is suppressed, and the dimensional accuracy of the hot press product is improved. can be suppressed and high productivity can be obtained.

It is a perspective view which shows the lower mold|type in a hot press molding apparatus. It is a perspective view which shows the lower mold|type and blank holder in a hot press molding apparatus. FIG. 4 is a schematic cross-sectional view of a mold of the hot press molding device; It is a figure which shows the processing process of the manufacturing method of a hot press product. It is a figure which shows the processing process of the manufacturing method of a hot press product. It is a figure which shows the processing process of the manufacturing method of a hot press product. It is a figure which shows the processing process of the manufacturing method of a hot press product. It is a figure which shows the to-be-shaped material length and metal mold|die cross-sectional shape when the drawing depth is deep. It is a figure which shows the to-be-molded product shape when the drawing depth is deep. It is a figure which shows the to-be-shaped material length and metal mold|die cross-sectional shape when drawing depth is shallow. It is a figure which shows the to-be-molded product shape when drawing depth is shallow. It is a figure which shows the to-be-shaped material length and metal mold|die cross-sectional shape in case a draw-up part is long. It is a figure which shows the to-be-molded product shape in case the draw-up part is long. It is a figure which shows the length of a to-be-shaped material and a metal mold|die cross-sectional shape when a draw-up part is short. It is a figure which shows the to-be-molded product shape in case the draw-up part is short. FIG. 10 is a diagram showing the length of the material to be molded and the cross-sectional shape of the mold when there is a vertical wall on the outer periphery; It is a figure which shows the to-be-molded product shape when there exists a vertical wall in outer periphery.

Embodiments of the present invention will be described in detail below with reference to the drawings.

Hereinafter, in describing the embodiments, the upper die attached to the drive side of the hot press forming device is lowered by the press drive, and the heated material is transferred to the lower die attached to the fixed side of the hot press device. A hot press forming method in which a punch is used to perform press forming in an upward direction will be described.

(Configuration of hot press molding device)
As shown in FIGS. 1 to 3, the mold 11 of the hot press molding apparatus 10 has a die 12 as an upper mold, a punch 13 as a lower mold, and a blank holder 14 for suppressing wrinkles. It can be drawn using a hot press machine. The basic configuration of the die 11 is the same as that of the cold press molding apparatus, but a coolant such as water is placed inside the die 12 and the punch 13 to cool the die 11 heated by the hot press molding. A plurality of water-cooled pipes (refrigerant flow paths) 15 and 16 are provided (see FIG. 3). Although the blank holder 14 may also be provided with the water-cooled pipes 15 and 16, the blank holder 14 of this embodiment is not provided with the water-cooled pipes 15 and 16. FIG. Also, the blank holder 14 is made of a steel plate instead of a general casting.

The blank holder 14 is held by a plurality of gas springs (elastic supports) 18 attached to a punch holder 17 (see FIG. 1). On the upper surface of the blank holder 14, fixed type (non-movable type) clearance control blocks (clearance maintaining portions) 21 having a diameter of approximately 70 mm are attached at intervals of 300 mm to 400 mm using bolts or the like. A cylindrical clearance control block 21 and a prismatic clearance control block 21 are arranged according to the mounting position (see FIG. 2).

The center of the gas spring 18 and the center of the clearance control block 21 are provided at substantially the same position. In other words, the gas spring 18 and the gap management block 21 are arranged concentrically at overlapping positions in plan view. For this reason, similarly to the clearance control block 21, 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 spring 18 and the gap control block 21 in this way, when the gap control block 21 is pushed down by the die 12, the blank holder 14 is pushed down with good balance. For this reason, a gap G (see FIGS. 4B and 4C) that is always set over the entire circumference of the molded material 20A is obtained during the molding process.

In this embodiment, an example in which the gap management block 21 is mounted on the upper surface of the blank holder 14 is shown, but it may be mounted on the outer peripheral portion (seat surface 23 ) of the die face surface 22 of the die 12 . Further, the clearance control block 21 may be provided integrally with the die 12 by casting, and may be formed by cutting the surface. In short, any arrangement may be used as long as the gap G between the die face surface 22 of the die 12 and the upper surface of the blank holder 14 can be correctly obtained by the gap management block 21 . The reason why the gap control block 21 is mounted on the upper surface of the blank holder 14 as described above is that the final adjustment of the gap G can be easily performed in the mold 11 using shims (spacers) or the like.

A die face surface 22 of the die 12 is provided with a seating surface (recessed portion) 23 at a position where the clearance control block 21 abuts during press molding. Moreover, the water cooling pipes 15 and 16 are not provided in the vicinity of the die face surface 22 of the die 12 . The gap G between the die face surface 22 of the die 12 and the upper surface of the blank holder 14 is adjusted by adjusting the height of the gap control block 21 so that the thickness of the material 20A to be formed +0.5 mm during hot press molding. is set. This gap G is not necessarily the plate thickness of the molded material 20A + 0.5 mm. The thickness of the molded material 20A + the gap G of 0.5 mm to 2.0 mm is assumed, and the material and thickness of the molded material 20A, the shape of the molded product 20B, the profile (cross-sectional shape) of the mold 11, etc. determined by

(Hot press molding method)
First, a material to be formed 20A is prepared, which has previously undergone external shape processing including guide holes for pilot pins, etc., by ordinary cold working. The material to be formed 20A is composed of a thin steel sheet for hot pressing, such as an aluminum-plated steel sheet or a galvanized steel sheet to which manganese, boron, or the like, which is an element for improving hardenability, is added.

The material to be formed 20A heated in the heating furnace is put onto the blank holder 14 in the mold 11 at the top dead center of the hot press machine using a transfer jaw (transfer robot) (not shown) or the like (Fig. 4A).

At this time, positioning of the molded material 20A is performed by a positioning pin (not shown) and a nest (not shown).

The die 12 is lowered by driving the hot press machine, and the upper surface of the clearance management block 21 mounted on the blank holder 14 comes into contact with the clearance management block contact portion (seat surface 23) provided on the die face surface 22. (See FIG. 4B).

As the die 12 is further lowered by driving the hot press, the bearing surface 23 provided on the die face surface 22 pushes the clearance management block 21 mounted on the blank holder 14 , thereby pushing down the blank holder 14 . At this time, the gas spring 18 is also pushed down and contracted in conjunction with the blank holder 14 . As a result, while the gap G between the die face surface 22 of the die 12 and the upper surface of the blank holder 14 remains the plate thickness of the material 20A + 0.5 mm, the material 20A is hot press-formed by the die 12 and the punch 13. (draw forming) (see FIG. 4C).

Further, as the die 12 is further lowered by driving the hot press machine, the heated molding material 20A is held loosely between the die face surface 22 and the blank holder 14, and is hot-pressed by the die 12 and the punch 13. It is press-molded (draw-molded).

Furthermore, as the die 12 is further lowered by the drive of the hot press machine, the drawn portion 24 on the outer periphery of the material 20A to be formed is drawn into the die 12 by the punch 13 about 5 mm before the bottom dead center, and the blank is formed. It exits from above the holder 14 (see FIG. 4D).

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

For example, when forming a shape having the same width (or diameter), the external shape of the material (blank material) 20A in a product with a deep drawing depth is the external shape of the material 20A in a product with a shallow drawing depth. (see FIGS. 5A and 5B, 6A and 6B). In addition, the clamping allowance C1 for the workpiece 20A in the product with a deep drawing depth is greater than the clamping allowance C2 for the workpiece 20A in the product with a shallow drawing depth (Figs. 5A and 5B, Figs. 6A and 6B reference).

On the same product, the outer shape of the part with a deep drawing depth is larger than the outer shape of the part with a shallow drawing depth (see FIGS. 5A and 6A). In addition, on the same product, the clamping allowance C1 for a portion with a deep drawing depth is greater than the clamping allowance C2 for a portion with a shallow drawing depth (see FIGS. 5A and 6A).

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

In the case where the drawn-up portion 24 on the outer periphery of the material 20A to be formed does not simply have a shape like a hat cross-section and a vertical wall 25 is provided, the clamping allowance C5 is such that the drawn-up portion 24 simply has a shape like a hat-like cross section. 9A and 9B, and FIGS. 8A and 8B).

As described above, the external shape of the material 20A to be formed differs depending on the drawing depth, the length and shape of the drawn up portion 24, etc., but in addition to these, the corners of the punch 13 may be rounded, and the cross section of the punch 13 may be changed. It is determined by tests, simulations, etc., including adjustment of the shape. Of course, since the outer shape differs depending on the type (steel type) of the material 20A to be formed, various tests are carried out using actual members and reflected in the simulation to determine the outer shape of the material 20A to be formed.

The effects of this embodiment will be described below.

(1) The method for manufacturing a hot press product according to the present embodiment uses a die and a punch 13 having water-cooled tubes 15 and 16 inside and a blank holder 14 to heat a heated forming material 20A. It is a method of manufacturing a hot press product by press molding. The die 12 and the punch 13 are brought close to each other to maintain 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 larger than the thickness of the material 20A to be molded. is drawn between the die 12 and the punch 13. Before reaching the bottom dead center of molding, the drawn up portion 24 on the outer periphery of the workpiece 20A is removed from the gap G between the die face surface 22 of the die 12 and the upper surface of the blank holder 14 . When the molding bottom dead center is reached, the drawn portion 24 on the outer periphery of the workpiece 20A does not remain in the gap G between the die face surface 22 of the die 12 and the upper surface of the blank holder 14, and the die 12 and the punch 13 do not remain. sandwiched between

(2) The gap G between the die face surface 22 of the die 12 and the upper surface of the blank holder 14 is set to a predetermined distance using the gap management block 21 provided between the die face surface 22 of the die 12 and the upper surface of the blank holder 14. to maintain.

(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 so that 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 larger than the thickness of the workpiece 20A. 20A is drawn between die 12 and punch 13 . Before reaching the bottom dead center of molding, the drawn up portion 24 on the outer periphery of the workpiece 20A is removed from the gap G between the die face surface 22 of the die 12 and the upper surface of the blank holder 14 . When the molding bottom dead center is reached, the drawn portion 24 on the outer periphery of the workpiece 20A does not remain in the gap G between the die face surface 22 of the die 12 and the upper surface of the blank holder 14, and the die 12 and the punch 13 do not remain. sandwiched between

(4) The hot press forming apparatus 10 is provided between the die face surface 22 of the die 12 and the upper surface of the blank holder 14, and the gap G between the die face surface 22 of the die 12 and the upper surface of the blank holder 14 is set to a predetermined value. A gap management block 21 is provided to maintain the gap.

(5) The clearance management block 21 is provided on at least one of the die face surface 22 of the die 12 and the upper surface of the blank holder 14 .

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

(7) The water cooling pipes 15 and 16 are not provided on the die 12 near the die face surface 22 and the blank holder 14 .

In the present embodiment, the die face 22 and the blank are held between the die 12 (die face 22) and the blank holder 14 until the completion of hot press forming (bottom dead center of the hot press). A gap G with the holder 14 is constant. Immediately before the bottom dead center, the drawn portion 24 of the material 20A is removed from the gap G, and finally the drawn portion 24 of the material 20A does not remain on the blank holder 14. - 特許庁Therefore, compared with the hot press forming method in which the workpiece 20A is strongly held between the die face surface 22 and the blank holder 14 at the bottom dead center, there is no sudden reduction in thickness (decrease in plate thickness). The occurrence of cracks is also suppressed in draw-formed products.

In the present embodiment, draw forming is performed until just before the bottom dead center, and form forming is performed from just before the bottom dead center to holding the bottom dead center (forming is completed). The timing at which the drawn-up portion 24 of the material 20A to be formed comes out of the gap G between the die face surface 22 and the blank holder 14 just before the bottom dead center is just before the bottom dead center of the hot press forming, and the form forming period is short. , the occurrence of wrinkles is also suppressed.

In short, in this embodiment, the molded product 20B has already come off the blank holder 14 at the bottom dead center. Therefore, when the bottom dead center is held, the molded product 20B can be rapidly cooled by uniform surface contact only with the die 12 and the punch 13 cooled by the refrigerant, and deterioration of cooling performance can be suppressed.

The improvement in cooling performance shortens the quenching time of the molded material 20A, shortens the time the molded material 20A is held in the mold, and improves productivity. In addition, since there is no uneven cooling in each part of the molded product 20B and there is no variation in the amount of bainite generated during the transformation of austenite to martensite, the molded product 20B has little variation in quenching hardness and can be used as a hot press product. dimensional accuracy is improved.

In the present embodiment, a fixed gap management block 21 (generally , S45C material) can be adopted. Therefore, the structure of the mold 11 can be simplified.

Also, the bearing surface 23 of the die face surface 22 that abuts on the gap control block 21 can be flattened in accordance with the production of the upper die, and the die 12 of the upper die does not have a complicated structure.

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

The size of the mold 11 can also be reduced by these various structural changes.

Furthermore, in this embodiment, the gap G between the die face surface 22 and the blank holder 14 during molding is always kept constant. Therefore, the die face surface 22 and the blank holder 14 do not become hot, and there is no need to use cooling devices such as water cooling pipes 15 and 16 in the vicinity of the die face surface 22 and in the blank holder 14 (see FIG. 3).

In this embodiment, the water cooling pipes 15 and 16 are not provided in the portion near the die face surface 22 of the die 12 and the blank holder 14 . Therefore, the die 12 and the punch 13 cooled by the coolant can rapidly cool the material 20A to the drawn-up portion 24 of the material 20A from the gap G immediately before the bottom dead center.

With the above contents, a more inexpensive hot press forming apparatus 10 can be obtained.

By the way, the hot press product manufacturing method and the hot press forming apparatus of the present invention have been described by taking the above-described embodiment as an example, but they are not limited to this embodiment and may be modified without departing from the gist of the present invention. Various embodiments of can be adopted.

As described above, the upper die attached to the drive side of the hot press forming device is lowered by the press drive, and the heated workpiece is pushed upward by the lower punch attached to the fixed side of the hot press device. An embodiment has been described for a hot press forming method for press forming in a direction. However, the upper mold (die) and lower mold (punch) may be reversed. That is, a hot press molding method may be used in which an upper punch and a lower die are used to perform press molding in the downward direction.

Further, in the hot press forming method described above, at the start of the hot press, in order to suppress wrinkles on the upper surface of the product, the material to be formed may be pressed in advance with a preceding pad and a punch before starting working with the die. Even in this case, since the material to be formed is removed from the blank holder, a locking mechanism for preventing buckling of the material to be formed is not required, and a more inexpensive hot press forming apparatus can be obtained.

10 hot press molding device 11 mold 12 die 13 punch 14 blank holder 15 water cooling pipe (refrigerant flow path)
16 water cooling pipe (refrigerant channel)
17 Punch holder 18 Gas spring 20A Molded material 20B Molded product 21 Gap control block (gap maintaining unit)
22 Die face surface (peripheral holding surface)
23 seat surface (recess)
24 Draw-up part 25 Vertical wall C1-C5 Clamp allowance G Gap

Claims (7)

A method for producing a hot press product by hot press forming a heated material to be formed using an upper mold and a lower mold having coolant channels inside and a blank holder, comprising:
The upper mold and the lower mold are brought closer to each other, and the gap between the outer peripheral pressing surface of the upper mold and the upper surface of the blank holder is maintained at a predetermined distance larger than the thickness of the material to be molded. Draw forming the material between the upper mold and the lower mold,
Before reaching the molding bottom dead center, the drawn up portion of the outer periphery of the workpiece is pulled out from the gap between the outer periphery pressing surface of the upper mold and the upper surface of the blank holder,
When the molding bottom dead center is reached, the drawn portion of the outer circumference of the workpiece does not remain in the gap between the outer circumference pressing surface of the upper mold and the upper surface of the blank holder, and the upper mold and the lower mold sandwiched between
A method for manufacturing hot pressed products. The gap between the outer peripheral pressing surface of the upper mold and the upper surface of the blank holder is maintained at the predetermined interval by using a gap maintaining part provided between the outer peripheral pressing surface of the upper mold and the upper surface of the blank holder.
A method for manufacturing a hot pressed product according to claim 1. Equipped with an upper mold and a lower mold having coolant channels inside, and a blank holder,
The upper mold and the lower mold are brought close to each other, and the gap between the outer peripheral pressing surface of the upper mold and the upper surface of the blank holder is maintained at a predetermined distance larger than the thickness of the material to be molded. The material is drawn between the upper mold and the lower mold,
Before reaching the molding bottom dead center, the drawn up portion of the outer periphery of the workpiece is pulled out from the gap between the outer periphery pressing surface of the upper mold and the upper surface of the blank holder,
When the molding bottom dead center is reached, the drawn portion of the outer circumference of the workpiece does not remain in the gap between the outer circumference pressing surface of the upper mold and the upper surface of the blank holder, and the upper mold and the lower mold sandwiched between
Hot press forming equipment. A gap maintaining part provided between the outer peripheral pressing surface of the upper mold and the upper surface of the blank holder and maintaining the gap between the outer peripheral pressing surface of the upper mold and the upper surface of the blank holder at the predetermined distance,
The hot press forming apparatus according to claim 3. The gap maintaining part is provided on at least one of an outer peripheral pressing surface of the upper mold and an upper surface of the blank holder,
The hot press forming apparatus according to claim 4. An elastic support part that elastically supports the blank holder,
The gap maintaining portion and the elastic support portion are positioned to overlap each other in a plan view,
The hot press forming apparatus according to claim 4 or 5. The coolant channel is not provided in the 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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