JP5786728B2 - Press forming method and apparatus - Google Patents

Description

  The present invention relates to a press molding method and apparatus for press molding a part having a groove portion having vertical walls on both sides.

In hot / warm press forming, in which press forming is performed by heating a metal plate material, the thickness of the molded product is partially reduced due to the shape of the molded product, which leads to cracks in the molded product. It has been considered to minimize the reduction in sheet thickness.
For example, as an example of hot pressing, in Patent Document 1, a molding surface of a mold is provided with a plurality of refrigerant discharge ports and a lubricating liquid supply port, and the deformation resistance and frictional resistance during molding are controlled to locally A hot press forming method that prevents the occurrence of breakage and scratches has been proposed.

Japanese Patent No. 4616737

In general, many automobile frame members have a hat-shaped groove-shaped cross section. In particular, a member that receives an impact force at the time of a collision called a collision member is required to have strength in the collision direction of the hat-shaped cross section. .
Side sills, bumper members, etc. are such collision members, and the vertical wall part in the hat-shaped cross section contributes to the collision strength, so there is a demand to make the vertical wall part relatively thicker than other parts. is there.

However, when a steel plate is heated and press-molded into a hat-shaped cross section with a mold, the punch usually comes into contact with the portion of the steel plate corresponding to the bottom of the hat-shaped cross section first. Deformation resistance increases.
On the other hand, the part of the steel plate that becomes the vertical wall is later in time than the part that makes contact with the mold, and the vertical wall has high clearance because the mold also has clearance. Deformation resistance during molding is small. Also, a large tension acts on the vertical wall during press molding. For this reason, the thickness of the vertical wall portion is smaller than that of the bottom portion during press molding.
If the thickness of the vertical wall is reduced, the strength of this part will decrease, so in order to ensure the strength of the part, the reduction of the thickness of the relevant part is taken into account, and the thickness of the metal plate as the material Therefore, the thickness of the portion other than the vertical wall increases, resulting in an increase in the weight of the entire part.

  In order to solve the above problem, even if a hat-shaped groove-shaped cross-sectional member is formed by the press molding method disclosed in Patent Document 1, the technique disclosed in Patent Document 1 suppresses a reduction in plate thickness during molding. Even if we can minimize the decrease in the thickness of the vertical wall, the thickness of the vertical wall is always thinner than the thickness of the bottom. After all, in order to secure the strength as a part, the entire plate thickness including the plate thickness of the vertical wall portion has to be increased.

  The present invention has been made to solve such a problem, and when press-molding a part having a groove-shaped portion having a vertical wall on both sides, the thickness of the bottom portion is further suppressed while suppressing a decrease in the thickness of the vertical wall. It is an object of the present invention to provide a press molding method and apparatus capable of reducing the thickness of the plate relative to the thickness of the vertical wall.

(1) A press forming method according to the present invention is a press for forming a heated plate material into a part having a groove portion having vertical walls on both sides by using a die and a punch that are divided so as to be widened. A molding method,
A step of pushing the die and the punch so that a portion of the die and the punch corresponding to the bottom of the groove-shaped portion does not contact the plate material to be formed; and the die and the punch move to a bottom dead center In this case, the die and the punch are moved in the widening direction while sandwiching the plate material to be formed, and the bottom portion is extended in the width direction.

(2) Moreover, the thing as described in said (1) WHEREIN: The cooling process which cools the said bottom part in the state which pinched | interposed the said to-be-molded plate material with the metal mold | die after the process of extending the said bottom part in the width direction was provided. It is a feature.

(3) A press molding apparatus according to the present invention is a press molding apparatus for press-molding a heated plate material into a part having a groove portion having vertical walls on both sides using a die and a punch,
In the portion corresponding to the bottom of the groove-shaped portion in the die and the punch, a concave portion is formed so that the portion and the plate material to be molded do not come into contact with each other.
The die and the punch are divided so as to be widened, and include a die widening means for widening the die and the punch in a state where the die and the punch are at bottom dead center.

(4) Further, in the above (3), the die is provided with a roller for reducing a friction with the plate member at a shoulder portion in the recessed portion.

(5) In the above (3) or (4), the punch is provided with a roller on the shoulder portion of the convex portion to reduce friction with the plate material. is there.

(6) Further, in the above (3) to (5), a cooling liquid supply means for supplying a cooling liquid for cooling the bottom of the molded plate material to the bottom at the bottom dead center is provided. It is a feature.

  A press molding method according to the present invention is a press molding method for press-molding a heated plate material into a part having a groove portion having vertical walls on both sides using a die and a punch, wherein the die and the die A step of pressing the die and the punch so that a portion of the punch corresponding to the bottom of the groove-shaped portion does not contact the plate member, and when the die and the punch move to the bottom dead center Since the die and the punch are moved in the widening direction and the bottom portion is extended in the width direction while sandwiching the plate material to be formed, the thickness of the vertical wall is reduced when the part is press-molded. In addition, the thickness of the groove-shaped portion can be relatively reduced as compared with the thickness of the vertical wall.

It is a figure explaining the press molding apparatus concerning Embodiment 1 of this invention. It is a figure explaining the press molding method using the press molding apparatus of FIG. 1 (the 1). It is a figure explaining the press molding method using the press molding apparatus of FIG. 1 (the 2). It is a figure explaining an example of the widening method of the press molding apparatus of FIG. It is a figure explaining the other example of the widening method of the press molding apparatus of FIG. It is a figure explaining the other example of the widening method of the press molding apparatus of FIG. It is a figure explaining the other aspect of the press molding apparatus of FIG. It is a figure explaining the press molding apparatus concerning Embodiment 2 of this invention. It is a figure explaining the press molding apparatus concerning Embodiment 3 of this invention. It is a figure explaining the press molding apparatus concerning Embodiment 4 of this invention.

[Embodiment 1]
In the following description, first, a press molding apparatus capable of performing the press molding method according to the present invention will be described, and then the press molding method according to the present invention using the press molding apparatus will be described.
As shown in FIG. 1, a press molding apparatus 1 according to the present embodiment is a component (hat) having a heated plate material 3 having a groove portion having vertical walls on both sides using a die 5 and a punch 7. In the press forming apparatus that press-forms the cross-sectional component), a concave portion S is formed in a portion corresponding to the bottom of the hat cross-sectional component in the die 5 and the punch 7 so as not to contact the portion and the plate material 3 to be molded. Thus, the die 5 and the punch 7 are divided so as to be widened, and are provided with mold widening means for widening the die 5 and the punch 7 in a state where the die 5 and the punch 7 are at the bottom dead center.
Hereinafter, the structure of the press molding apparatus 1 is demonstrated based on FIGS.

<Die and punch>
As shown in FIG. 1, the die 5 and the punch 7 are each composed of a pair of members that can be divided from the center to the left and right.
As shown in FIGS. 1 and 2, the die 5 and the punch 7 are used in an integrated state without being divided as shown in FIGS. 1 and 2. At the bottom dead center, as shown in FIG. The pair of members can be moved in the widening direction.
Further, as shown in FIGS. 1 and 2, the portion of the die 5 and the punch 7 that forms the bottom of the hat cross-section part has a recess S so as not to contact the plate material 3 to be pressed. Further, at the bottom dead center (see FIG. 2), the heat of the molded plate member 3 is hardly taken away at this portion.

<Mold widening means>
The mold widening means of the present invention is for moving the pair of members of the die 5 and the punch 7 in the widening direction. This movement is performed so that the movement distance and the movement timing of the pair of members of the die 5 and the pair of members of the punch 7 are always the same. By doing so, the plate member 3 can be moved in the widening direction with the die 5 and the punch 7 sandwiched.

An example of the mold widening means of the present invention is shown in FIG. The mold widening means 9 in FIG. 4 has a wedge receiving portion 11 and a wedge receiving portion 13 having a substantially V-shaped cross section below the die 5 and above the punch 7 in a state where the pair of members are integrated. The wedges 15 and 17 having a substantially trapezoidal cross section are inserted and slid from the opening side of the wedge receivers 11 and 13, and the pair of members are moved in the widening direction.
The angle formed by each of the substantially V-shaped shapes and the angle formed by the wedges 15 and 17 are the same, and the speed at which the wedges 15 and 17 are inserted and slid is also the same. By doing so, the movement distance and the movement timing of each of the pair of members can always be the same.

  The mold widening means of the present invention is not limited to the above-described ones, and various modes can be adopted. For example, an example using an oil cylinder is shown in FIG. The mold widening means 19 in FIG. 5 has a plurality of oil cylinders 21 attached so as to extend over the pair of members of the die 5, and a plurality of oil cylinders 23 attached to the pair of members of the punch 7. The oil cylinders 21 and 23 are driven to move the pair of members in the widening direction.

  Further, as a modification of the mold widening means 19, as in the mold widening means 25 shown in FIG. 6, a pair of members constituting the die 5 and a fixing portion of the wall 27 disposed outside the die 5. A plurality of oil cylinders 29 may be installed in between, and by driving these oil cylinders 29, each member constituting the die 5 may be pulled toward the wall 27 side.

  In order to make the movement distance and the movement timing of each pair of members always the same in the mold widening means 19 or the mold widening means 25, the oil cylinders 21 and 23 shown in FIG. 5 or the oil shown in FIG. The cylinders 23 and 29 are controlled to have the same stroke at the same timing.

In addition, as an integrated means for maintaining a state in which the pair of members of the die 5 and the punch 7 divided to the left and right at the bottom dead center are integrated, for example, a member such as a hydraulic mechanism or a spring that constantly applies a pressing force May be provided.
The number of oil cylinders 21, 23, 29 in the mold widening means 19, 25 is not limited to that shown in FIGS. 5 and 6, and may be appropriately determined according to the size of the die 5 or the punch 7. Just decide.

  Next, the press molding method according to the present embodiment using the press molding apparatus 1 will be described in detail based on FIGS. 1 to 3 and FIG.

  First, as shown in FIG. 1, the heated plate material 3 is placed so as to cover the recessed portion of the die 5, and the pair of members constituting the die 5 and the punch 7 are integrated and pressed. I do. During pressing and at the bottom dead center (see FIG. 2), the bottom portion of the hat cross-section component of the plate member 3 is not in contact with the die 5 and the punch 7 due to the presence of the recess S. It remains at a relatively high temperature as compared with the portion that becomes the vertical wall, and its deformation resistance is small. Accordingly, during pressing, the material flow occurs in the bottom portion and the plate thickness decreases, while the material flow decreases in the vertical wall portion and the reduction in the thickness of the portion is suppressed. .

Next, as shown in FIG. 3, each pair of members constituting the die 5 and the punch 7 is moved by a predetermined distance in the widening direction using the mold widening means of the present invention. At this time, the portion serving as the bottom of the hat cross-sectional component remains at a high temperature as described above, so that the deformation resistance is small and can be stretched in the widening direction relatively easily. In addition, the thickness of the bottom further decreases with the extension.
In this state, if the product to be molded is sufficiently cooled, press molding is completed. In addition, since the bottom part of hat cross-section components remains comparatively high temperature, it is preferable to cool enough and to give tensile strength. For example, as shown in FIG. 7, a cooling oil supply device 33 that supplies cooling oil via a cooling oil pipe 31 communicating with the recess S is provided as shown in FIG. The thing which cools is mentioned.

  As described above, if press molding is performed using the press molding apparatus 1 according to the present embodiment, it is possible to suppress a reduction in the thickness of the vertical wall portion. Further, the thickness of the bottom portion can be reduced compared to the thickness of the vertical wall portion, and the weight can be reduced.

  In addition, in the space of S part, when a fracture | rupture generate | occur | produces when expanding a metal mold | die and extending a to-be-molded board material, it is necessary to extend a to-be-molded board material uniformly. Various means for uniformly extending the plate material to be molded can be applied. For example, it is preferable to put a roll in the S part to make the plate material thin.

[Embodiment 2]
As shown in FIG. 8, the press molding apparatus 41 according to the present embodiment has the same basic configuration as the press molding apparatus 1 according to the first embodiment, and is formed with both the shoulder portions of the recessed portions of the die 5 and the plate material 3 to be molded. A roller 43 for reducing friction is provided.

  The roller 43 is a roller having the same radius of curvature as both shoulders in the recessed portion of the die 5 of the press molding apparatus 1, and is rotatably installed on both shoulders in the recessed portion of the die 5. Friction can be reduced by rotating the roller 43 when the plate material 3 to be molded enters the recessed portion of the die 5 during pressing.

  If the press molding apparatus 41 according to the present embodiment is used, the friction during pressing can be reduced, the tension acting on the vertical wall portion can be reduced, and the reduction in plate thickness can be suppressed, and the thickness of the vertical wall portion can be suppressed. Can be kept thick.

[Embodiment 3]
As shown in FIG. 9, the press forming apparatus 47 according to the present embodiment has the same basic configuration as that of the press forming apparatus 1 of the first embodiment, and friction between the projecting plate material 3 and the convex shoulders of the punch 7. The roller 45 which reduces this is provided.

  The roller 45 is a roller having the same curvature radius as that of both shoulders of the convex portion of the punch 7 of the press molding apparatus 1, and is rotatably installed on both shoulders of the convex portion of the punch 7. Friction can be reduced by rotating the roller 45 when the plate member 3 is pressed by the convex portion of the punch 7 during pressing.

If the press molding apparatus 47 concerning this Embodiment is used, the friction at the time of a press can be reduced, the tension | tensile_strength which acts on a vertical wall part can become low, and plate | board thickness reduction can be suppressed.
Further, when the pair of members constituting the die 5 and the punch 7 are moved by a predetermined distance in the widening direction by using the mold widening means of the present invention, the roller 45 can move even slightly, so that the widening direction The tension acting on the sheet can be made almost uniform over the longitudinal direction (the direction perpendicular to the paper surface of FIG. 9), and stable molding becomes possible.

[Embodiment 4]
In the first to third embodiments described above, the method of press-molding the hat cross-section component has been described. However, the present invention can also be applied to the molding of a substantially W cross-section component in which two hat cross-section components are connected in the width direction.
As shown in FIG. 10, the press molding apparatus 51 according to the present embodiment has a mold (W-shaped die 53 and W-shaped) in which two molds of the press molding apparatus 41 (FIG. 8) are connected in the width direction. A die punch 55). Each of the W-shaped die 53 and the W-shaped punch 55 is composed of three members that can divide the recessed portion and the protruding portion provided in two places vertically from their centers, and are arranged at both ends. The mold is movable in the widening direction.
Further, the press molding apparatus 51 may have a roller 43, similarly to the press molding apparatus 41.

In order to form a substantially W cross-section component using the press molding device 51, the heated plate material 3 is placed so as to cover both concave portions of the W-shaped die 53, and thereafter the same as in the second embodiment. Press forming.
If the press molding apparatus 51 is used, as in the second embodiment, it is possible to suppress a reduction in the plate thickness of the vertical wall portion of the substantially W-section component, and the bottom plate compared to the plate thickness of the vertical wall portion. The weight can be reduced by reducing the thickness.

In Example 1, since an experiment for confirming the effect of press forming using the press forming apparatus 41 (FIG. 8) according to the second embodiment was performed, a description will be given below.
The experiment was performed using the press molding apparatus 41 according to the method shown in the second embodiment, and as a comparative example, the conventional method using a normal mold as a comparative example was the same as the present invention example 1. It is the comparative example 1 which shape | molds this press-molded article. In addition, both the present invention example 1 and the comparative example 1 used the plate material 3 to be molded by heating a hot-press steel plate having a thickness of 1.6 mm to 950 ° C.

When the hat cross-section parts molded in the inventive example 1 and the comparative example 1 were compared, the outer dimensions such as the dimensions of the bottom part were the same, but the plate thickness of the vertical wall part was the comparative example 1 of the conventional example 1. It was reduced by about 10%.
As described above, it has been confirmed that if press molding is performed by applying the present invention, a reduction in the thickness of the vertical wall portion can be suppressed as compared with the case of performing normal press molding.

Next, since the experiment which confirms the effect of press molding using the press molding apparatus 51 (FIG. 10) concerning the said Embodiment 4, the result is demonstrated below.
In the experiment, Example 2 of the present invention in which the present invention is applied and the conventional method using a normal mold, the material having the same thickness as that of Example 2 of the present invention is formed into the same shape as Example 2 of the present invention. It is the comparative example 2 which press-forms, and the comparative example 3 which thickens the plate | board thickness of a to-be-molded material and performs press molding similar to the comparative example 2. FIG. The material to be molded was heated to 950 ° C. and used.
Table 1 summarizes the press-formed products of each experiment.

As shown in Table 1, the press-formed product of Example 2 of the present invention had a thickness of 1.58 mm in the vertical wall after molding, and the thickness reduction from 1.6 mm of the plate material to be molded was slight. On the other hand, in the press-formed product of Comparative Example 2, the thickness of the vertical wall portion after molding was 1.1 mm, and a large reduction of about 30% was observed.
Further, as a performance comparison between the press-formed products of Invention Example 2 and Comparative Example 2, when the bending crush performance was compared, as shown in Table 1, the bending crush performance of the press-formed product of Invention Example 2 was used as a reference. Then, the performance of Comparative Example 2 was about 85%. This is because the plate thickness of the vertical wall portion of Comparative Example 2 is reduced.

The press-formed product of Comparative Example 3 is an example in which the plate thickness after molding and the bending crush performance are the same as those of Example 2 of the present invention. Thus, it was greatly increased to 132% of Example 2 of the present invention. This means that, in the conventional press molding method, the weight increases by about 30% in order to exhibit the same performance as that of Example 2 of the present invention. In other words, the press-formed product of Example 2 of the present invention can be reduced by about 30% while maintaining the same level of performance as a conventional press-formed product.
Therefore, it was demonstrated that the bending crushing performance can be improved without increasing the weight by performing press molding to which the present invention is applied.

DESCRIPTION OF SYMBOLS S Clearance 1 Press molding apparatus 3 Mold plate material 5 Die 7 Punch 9 Mold widening means 11 Wedge receiving part 13 Wedge receiving part 15 Wedge 17 Wedge 19 Mold widening means 21 Oil cylinder 23 Oil cylinder 25 Mold widening means 27 Wall 29 Oil cylinder 31 Cooling oil pipe 33 Cooling oil supply device 41 Press molding device 43 Die shoulder roller 45 Punch shoulder roller 47 Press molding device 51 Press molding device 53 W-shaped die 55 W-shaped punch

Claims (6)

A press molding method for press-molding a heated plate material using a die and a punch that are divided so as to be widened into a part having a groove portion having vertical walls on both sides,
A step of pushing the die and the punch so that a portion of the die and the punch corresponding to the bottom of the groove-shaped portion does not contact the plate material to be formed; and the die and the punch move to a bottom dead center A press forming method, comprising: a step of moving the die and the punch in the widening direction with the plate material being sandwiched between them to extend the bottom in the width direction.   The press molding method according to claim 1, further comprising a cooling step of cooling the bottom portion in a state where the plate material to be molded is sandwiched between molds after the step of extending the bottom portion in the width direction. A press molding apparatus that press-molds a heated plate material into a part having a groove portion having vertical walls on both sides using a die and a punch,
In the portion corresponding to the bottom of the groove-shaped portion in the die and the punch, a concave portion is formed so that the portion and the plate material to be molded do not come into contact with each other.
2. The press molding apparatus according to claim 1, wherein the die and the punch are divided so as to be widened, and a die widening means is provided for widening the die and the punch while the die and the punch are at bottom dead center.   4. The press molding apparatus according to claim 3, wherein the die includes a roller on a shoulder portion of the recessed portion to reduce friction with the plate material to be molded.   The press forming apparatus according to claim 3 or 4, wherein the punch includes a roller on a shoulder portion of a convex portion to reduce friction with the plate material to be formed. 6. The press molding apparatus according to claim 3, further comprising a coolant supply means for supplying a coolant for cooling the bottom of the plate material to be formed to a bottom dead center.

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