WO2008032172A1

WO2008032172A1 - Press machine and manufacturing method using the same

Info

Publication number: WO2008032172A1
Application number: PCT/IB2007/002597
Authority: WO
Inventors: Toshihiro Fukushima; Hisanori Nakamura; Shinji Kato; Kiyochika Soma; Masahiko Ueno; Hirokazu Okada; Kiyokazu Baba; Hiroaki Honma; Masahide Sunata; Hajime Yoshida; Hirohide Sato
Original assignee: Toyota Jidosha Kabushiki Kaisha; Komatsu Ltd.; Komatsu Industries Corp.
Priority date: 2006-09-13
Filing date: 2007-09-11
Publication date: 2008-03-20
Also published as: WO2008032172A8; JP2008068280A; DE112007002149T5

Abstract

A press machine includes a bolster (7) on which a lower die is placed and a bolster carrier (9) that supports at least a part of a peripheral portion and a substantially center portion of the bolster. In this way, a portion of press load or energy consumed in a deformation or deflection of the bolster is reduced, thereby reducing a loss of the press load.

Description

PRESS MACHINEAND MANUFACTURING METHOD USING THE SAME

BACKGROUND OF THE INVENTION

1. Field of the Invention

[0001] The invention relates to a press machine, and more specifically, to a press machine in which a lower die is supported by a bolster. The invention also relates to a manufacturing method using the press machine.

2. Description of the Related Art

[0002] Japanese Patent Application Publication No. H6-190464 (JP-A-H6- 190464) describes a press machine that equalizes the distribution of blank holder force applied to a cushion ring using a die cushion. For example, in a press machine 1 as shown in FIG. 6, a die cushion 6 includes a plurality of cushion pins 3, a cushion pad 4, and cushions 5. The plurality of cushion pins 3 support the cushion ring 2, and the cushion pad 4 supports the plurality of cushion pins 3. The cushions 5 receive the blank holder force applied to the cushion pad 4. The die cushion 6 absorbs the effects of the inclined cushion ring 2, variation in the length of the cushion pins 3, deviation in parallelism of the cushion pad 4 with respect to the bolster 7, and distortion of the main body of the press machine 1, whereby the distribution of blank holder force applied to the cushion ring 2 is well equalized. In the press machine 1 thus configured, a lower die 8 is placed on a top surface of the bolster 7 at the center thereof, and the bolster 7 is supported by a bed 10 through a bolster carrier 9 (for example, see paragraphs [0011] to [0032] and FIGS. 1 to 4 of JP-A-H6-190464).

[0003] In the press machine 1, a periphery of the bolster 7 is supported by the frame-shaped bolster carrier 9. _ Therefore, the center portion of the bolster 7 is concavely deflected due to a press load applied, resulting in wasting energy (load) by the deflection of the bolster 7, that is, generating a loss of the energy (load). Accordingly, as the energy consumption increases, the production costs increases, and the amount of carbon dioxide discharged also increases. Moreover, when the type of the press machine 1 that is capable of generating a larger press load is required in order to compensate for the loss of the energy, the press machine needs to be larger in size, whereby the facility cost increases.

SUMMARY OF THE INVENTION

[0004] The invention provides a press machine and a manufacturing method using the press machine, in which the loss of the energy (press load) is reduced.

[0005] A press machine according to an aspect of the invention includes: a bolster on which a lower die is placed; and a bolster carrier that supports at least a part of a peripheral portion of the bolster and a substantially center portion of the bolster. According to the aspect, the center portion of the bolster is avoided from being concavely deflected due to the press load applied.

[0006] The bolster carrier may includes: a frame that is rectangular shaped and supported by a bed; and a first rib that is cross-shaped and supports the substantially center portion of the bolster at an intersection of the cross-shaped first rib. The press machine may further include a post that stands at a substantially center of a die cushion housing portion formed in the bed and that supports the intersection of the first rib of the bolster carrier. Further, the press machine may further include a second rib that is cross-shaped and disposed in the die cushion housing portion formed in the bed, and that supports a substantially center portion of the first rib of the bolster carrier.

[0007] Another aspect of the present invention provides a method for manufacturing a component. In the manufacturing method, a workpiece is set between an upper die and a lower die, and the upper die is lowered. Then, the workpiece is held between the upper die and a cushion ring disposed to surround the lower die. The workpiece is draw formed into the component between the upper die and the lower die, while a press load applied to the lower die is supported by a substantially center portion and a peripheral portion of a bolster on which the lower die is placed. According to this aspect of the invention, the center portion of the bolster is avoided from being concavely deflected due to the press load applied, thereby reducing the loss of the energy (press load).

BRIEF DESCRIPTION OF THE DRAWINGS

[0008] The foregoing and further objects, features and advantages of the invention will become apparent from the following description of example embodiments with reference to the accompanying drawings, wherein like numerals are used to represent like elements and wherein:

FIG. 1 is an exploded perspective view showing a bolster, a bolster carrier, and a bed of a press machine according to an embodiment;

FIG. 2 is a partially sectional front view showing the press machine according to the embodiment;

FIG. 3 is an exploded perspective view showing a bolster, a bolster carrier, and a bed of a press machine according to another embodiment;

FIG. 4 is a perspective view showing the bed that is partially cut away and a cushion pad that corresponds to the bed of the press machine according to another embodiment;

FIG. 5 is a partially sectional front view showing the press machine according to another embodiment; and

FIG. 6 is a partially sectional front view showing a conventional press machine.

DETAILED DESCRIPTION OF THE EMBODIMENTS

[0009] An embodiment of the invention will be described with reference to FIGS. 1 and 2. It should be noted that the configurations that are the same as or equivalent to those in the conventional press machine 1 described as above will be denoted by the same names and reference numerals. As shown in FIG. 1, the press machine 1 is provided with the bolster carrier 9 on which the bolster 7 is placed. The bolster carrier 9 includes a frame 11 that is rectangular shaped. A rib 12 (first rib), which is formed by two beams crossed at the center, is provided inside the frame 11. An intersection Cl of the rib 12 is supported by a post 14 that stands at the substantially center of a die cushion housing portion 13 formed in a bed 10. Therefore, the center of the bolster 7 is also supported by the post 14 through the intersection Cl of the rib 12 disposed in the bolster carrier 9. In this way, in the press machine 1, the center portion of the bolster 7 is prevented from being concavely deflected due to the press load applied, thereby reducing the loss of the press load (energy), that is, reducing a portion of the press load consumed by other than stamping.

[0010] As shown in FIG. 2, in the press machine 1, the bed 10 (lower frame) is housed in a pit 15 made of concrete, and a crown 17 (upper frame) is supported by side plates 16 (intermediate frames) that stand in both sides of the bed 10 in a width direction thereof (in a horizontal direction in FIG. 2). Further, the press machine 1 includes a slider 18 that is supported by the crown 17 through a pair of shafts 19, and an upper die 20 is installed on a bottom surface (the upper die installation surface) of the slider 18. The press machine 1 includes the pair of the shafts 19 that move in an axial direction (in a vertical direction in FIG. 2) by a driving force generated by a slider drive mechanism (servo drive mechanism) provided in the crown 17. The pair of the shafts 19 reciprocate and position the slider 18 and the upper die 20, which is installed on the installation surface of the slider 18, in a vertical direction (in the vertical direction in FIG. 2). Further, in the press machine 1, the lower die 8 (punch) is installed on a top surface (the lower die installation surface) of the bolster 7 at the center thereof, and the frame-shaped cushion ring 2 (lower die pad) is disposed so as to surround the lower die 8.

[0011] As shown in FIG. 2, the cushion ring 2 is supported by a die cushion 6 that includes a plurality of cushion pins 3, a cushion pad 4, and a plurality of cushions 5. The die cushion 6 is configured such that an upper end of each of the plurality of cushion pins 3 is abutted against a bottom surface of the cushion ring 2, and the cushion pins 3 perpendicularly penetrate the bolster 7 such that the cushion pins 3 can reciprocate in an axial direction thereof (in the vertical direction in FIG. 2). The die cushion 6 receives the blank holder force applied to the cushion ring 2 on the cushion pad 4, which is housed in the die cushion housing portion 13 formed in the bed 10, through the cushion pins 3. In the die cushion 6, the plurality of cushions 5, which are disposed in the die cushion housing portion 13 formed in the bed 10, finally receive the blank holder force received by the cushion pad 4.

[0012] As shown in FIG. 1, beams 12a, 12b are provided in the frame 11 between two mutually opposing inner side surfaces of the frame 11, respectively, and the beams 12a, 12b are disposed to form the cross-shaped rib 12 in which the beam 12a and the beam 12b cross at the substantially center of the frame 11. The bolster carrier 9 is supported on the bed 10 in a manner that the frame 11 is supported by a peripheral portion of an opening in the bed 10, which serves as the die cushion housing portion 13. The intersection Cl of the rib 12 is supported by the post 14. Note that, the bolster carrier 9 is configured such that a top surface of the frame 11 and a top surface of the rib 12 are flush with each other (formed in the same plane), and a bottom surface of the frame 11 and a bottom surface of the rib 12 are also flush with each other. Further, the cushion pad 4 is provided with a space 22 therein in order to avoid interference between the cushion pad 4 and the post 14.

[0013] Next, functions of the press machine 1 will be described. First of all, as shown in FIG. 2, a workpiece 21 (steel plate) is placed between the upper die 20 and the lower die 8. Then, when the upper die 20 is lowered, the workpiece 21 is constrained between the upper die 20 and the cushion ring 2 (lower pad) at a predetermined constraint force (blank holder force), and in the constraint state, the workpiece 21 is draw formed between the upper die 20 and the lower die 8. During this, the die cushion 6 receives the blank holder force applied to the cushion ring 2. On the other hand, the bolster 7 receives the press load applied to the lower die 8, and the bed 10 further receives the press load received by the bolster 7 through the bolster carrier 9. The bolster carrier 9 is supported in a manner that the entire bottom surface of the frame 11 is supported by the top surface of the bed 10, and at the same time, the intersection Cl (at the center of the bolster carrier 9) of the rib 12 (first rib) is supported by the post 14 that stands at the center of the die cushion housing portion 13 formed in the bed 10. In other words, the workpiece 21 is draw formed between the upper die 20 and the lower die 8, while the press load applied to the lower die 8 is supported by the peripheral portion and the center portion of the bolster 7. [0014] In this way, in the press machine 1, the center portion of the bolster 7 is supported by the post 14, which stands in the bed 10, through the intersection Cl of the rib 12 provided in the bolster carrier 9. Therefore, the center portion of the bolster 7 is avoided from being concavely deflected due to the press load applied. It should be noted that, according to the experimental data, when stamping (draw forming) a steel plate into a component, such as a vehicle side member, the press load, which was applied when stamping the steel plate using the press machine 1 according to the above-described embodiment, was only one-third to one-fifth of the press load applied when using the conventional press machine 1 (see FIG. 6). In the experiment, the amount of deflection of the bolster 7 in the press machine 1 according to the above-described embodiment was equal to or even less than one-half of the amount of deflection of the bolster 7 in the conventional press machine 1. Accordingly, in the press machine 1 according to the above-described embodiment, the amount of deflection of the bolster 7 was reduced to around one-half of the conventional amount of deflection, thereby reducing the loss of the press load (energy).

[0015] The embodiment described herein has the following effects. In the press machine 1, the cross-shaped rib 12 (first rib) is formed inside the frame 11 of the bolster carrier 9, and the intersection Cl the cross-shaped rib 12 is supported by the post 14 that stands at the center of the die cushion housing portion 13 formed in the bed 10. Accordingly, in the press machine 1, the center portion of the bolster 7 is supported by the post 14 through the intersection Cl of the rib 12 formed in the bolster carrier 9. In this way, in the press machine 1, the center portion of the bolster 7 is prevented from being concavely deflected due to the press load applied, thereby reducing the portion of the press load (energy) consumed in deformation (deflection) of the bolster 7, in other words, reducing the loss of the press load. As a result, the production cost is reduced, and moreover, the facility can be downsized because the press machine 1 that generates only smaller press load can do the desired work. Further, in the press machine 1 according to the invention, because the rib 12 is cross-shaped, the rigidity of the bolster carrier 9 is increased, and the restriction in arrangement of the cushion pins 3 is minimized, such that the cushion pins 3 can be arranged in an effective manner. Further, in the press machine 1, the intersection 'Cl of the rib 12 provided in the bolster carrier 9 is supported by the post 14 in an axial direction of the post 14. Therefore, the press machine 1 can handle a relatively large press load in a simple configuration.

[0016] FIGS. 3 to 5 show a press machine in another embodiment. As shown in the drawings, a rib 25 (second rib) may be provided in the bed 10, instead of providing the post 14 that stands at the center of the die cushion housing portion 13 formed in the bed 10. The rib 25 is cross-shaped, and divides the die cushion housing portion 13, which is rectangular shaped in a plan view (when viewed from the top in FIG. 5), into four sections, in other words, two sections in the longer side and two sections in the shorter side of the rectangular die cushion housing portion 13. In this way, the rib 25 provided in the bed 10 reinforces the rigidity of the bed 10, and moreover, the bolster 7 is prevented from being deflected due to the press load applied because the rib 25 in the bed

10 supports the entire rib 12 (first rib) provided inside the bolster carrier 9. In this case, the cushion pad 4 is provided with a slit 26, which is cross-shaped in a plan view, such that the rib 25 in the bed 10 is inserted and fitted into the cross-shaped slit 26. In this way, the interference between the cushion pad 4 and the rib 25 of the bed 10 can be avoided.

[0017] Note that, in the aforementioned embodiment, the first rib is formed by two beams that are disposed in parallel to the longer side and the shorter side of the rectangular frame, respectively, and that are perpendicularly crossed, such that the first rib connects between the opposing inner side surfaces of the rectangular frame. However, the aforementioned beams may not necessarily extend in parallel to the sides of the rectangular frame, and may not necessarily be perpendicularly crossed. Further, one of the beams may not necessarily be connected or fixed to the side surfaces of the frame

11 (e.g., the rib may be T-shaped). Further, only one beam may be provided, and the rib may not necessarily be cross-shaped.

[0018] While some embodiments of the invention have been illustrated above, it is to be understood that the invention is not limited to details of the illustrated embodiments, but may be embodied with various changes, modifications or improvements, which may occur to those skilled in the art, without departing from the spirit and scope of the invention.

Claims

1. A press machine comprising: a bolster on which a lower die is placed; and a bolster carrier that supports at least a part of a peripheral portion of the bolster and a substantially center portion of the bolster.

2. The press machine according claim 1, wherein the bolster carrier includes: a frame that is rectangular shaped and supported by a bed; and a first rib that is cross-shaped and supports the substantially center portion of the bolster at an intersection of the cross-shaped first rib.

3. The press machine according to claim 2, further comprising a post that stands at a substantially center of a die cushion housing portion formed in the bed and that supports the intersection of the first rib of the bolster carrier.

4. The press machine according to claim 2, further comprising a second rib that is cross-shaped and disposed in the die cushion housing portion formed in the bed, and that supports a substantially center portion of the first rib of the bolster carrier.

5. The press machine according to claim 4, wherein a shape of the second rib corresponds to a shape of the first rib so as to support the entire first rib.

6. The press machine according to claim 2, wherein the first rib is provided to connect between inner surfaces of the frame that are opposed to each other.

7. The press machine according to claim 2, wherein a top surface of the frame and a top surface of the first rib are disposed in a same plane, and a bottom surface of the frame and a bottom surface of the first rib are disposed in a same plane.

8. The press machine according to claim 3, further comprising a cushion pad that is housed in the die cushion housing portion and is provided with a space through which the post stands.

9. The press machine according to claim 5, further comprising a cushion pad that is housed in the die cushion housing portion and is provided with a slit into which the second rib is inserted.

10. A method for manufacturing a component, comprising: setting a workpiece between an upper die and a lower die; lowering the upper die; holding the workpiece between the upper die and a cushion ring disposed to surround the lower die; and draw forming the workpiece into the component between the upper die and the lower die, while a press load applied to the lower die is supported by a substantially center portion and a peripheral portion of a bolster on which the lower die is placed.