JPH10180470A - Differential thickness tailored blank forming method, and differential thickness tailored blank - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent breakage of a joined part by regulating the butt step of plates on the side where the expansion forming force is applied in the prescribed range to prevent a large shearing force from being applied to the joined part during the pressing in forming the differential thickness tailored blank of a parts in which members of different thickness and different strength are joined with each other and whose expansion forming direction is changed. SOLUTION: A differential thickness tailored blank 1 comprises a thinner plate 2, a thicker plate 3, and a joined part 4, and the butt step (d) of the plates is formed in the joined part 4. The expansion forming is performed in the direction of the arrow. When the butt step (d) of the plates is increased, the shearing force to be applied to the joined part 4 during the forming becomes excessive leading to the breakage of the joined part, and based on the results of the forming test, the butt step (d) of the plates on the side where the expansion forming force is applied, is in the condition to satisfy the inequality of F3 .d/F2 .t2 <0.5, where t2 is the thickness of the thinner plate 2, F2 is the tensile strength thereof, t3 is the thickness of the thicker plate 3, and F3 is the tensile strength thereof, and the butt position is changed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a differential thickness tailored blank material which is preferably used as a material for a part in which different types of plate materials having different thicknesses and strengths are butt-joined and the direction of overhang forming of the plate material varies depending on the portion. The present invention relates to a forming method and a differential thickness tailored blank material.

[0002]

2. Description of the Related Art As a conventional differential thickness tailored blank material, for example, there is one shown in FIG.

In FIG. 5, reference numeral 51 denotes a differential thickness tailored blank, 52 denotes a thin side plate of the differential thickness tailored blank 51, 53 denotes a thick side plate of the differential thickness tailored blank 51, and 54 denotes a differential thickness tailored blank. Blank material 51
The reference numeral 55 denotes a recessed portion such as an emboss in the tailored blank material 51 having a different thickness.

[0006] In FIG. 6, an arrow A indicates a direction in which the sheet material is stretched during press forming of the differential thickness tailored blank material 51.

More specifically, in this differential thickness tailored blank 51, the positional relationship at the joint 54 between the thin plate 52 and the thick plate 53 is always constant. In the conventional case shown in the drawings, the thin plate 52 and the thick plate 53 are joined in such a manner that in a hat (hat) shape, the butted step of the inner plate is always zero.

At the time of press forming, a bulging force in the bulging direction of the plate material indicated by arrow A acts.
More specifically, for a portion other than the recessed portion 55 such as an embossed portion, in the shape of a hat, an overhanging force in the upwardly directed overhanging direction A is applied to the plate material from the inside thereof, and the recessed portion 55 such as an embossed portion is provided. With respect to the portion, in the shape of the hat, a bulging force in the bulging direction A downward from the outside in the figure is applied to the plate material.

[0007]

However, in such a conventional differential thickness tailored blank material 51,
Since the butted position of the different plate materials 52 and 53 was always constant and did not change depending on the part, a part where the butted step of the plate material on the overhang forming side became large occurred, and press forming was performed on the part. In such a case, there is a problem that a shear force may be applied to the joint to cause breakage of the joint, and it may not be possible to manufacture a component with high accuracy.

[0008]

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned conventional problems, in which different types of plate materials having different thicknesses and strengths are butt-joined to each other, and the direction of the overhanging of the plate materials depends on the portion. In the tailored blank material used as the material for changing parts, the butting position of the thin side plate and the thick side plate is changed depending on the part, and the butting step on the side where the overhang forming force is applied to all parts is specified. The object is to solve the above problem by the following.

[0009]

SUMMARY OF THE INVENTION According to the present invention, there is provided a method for forming a tailored blank having a thickness different from that of a part having different thicknesses and strengths, butting and joining different types of parts. when forming a different thickness tailored blank material used as a material, a thin plate-side plate is the plate thickness t ₂ a and a tensile strength F _2, when plank plate material is and a tensile strength F ₃ a plate thickness t ₃ The butting step d of the plate material on which the overhang forming force is applied is always It is characterized in that it is formed into a tailored blank material having a different thickness suitable as a material of a component in which the direction of the overhang forming of the plate material changes depending on the portion by joining at the abutting position.

A tailored blank having a different thickness according to the present invention is a differential thickness tailored blank which is used as a material for a part in which different types of plates having different thicknesses and strengths are butt-joined and joined, and the direction of overhang of the plate varies depending on the portion. in the blank, thin side plate is the plate thickness t ₂ a and a tensile strength F _2, when plank plate material is a plate thickness t ₃ a and a tensile strength F _3, the consuming bulging force side of the plate Butt step d
But always In which the abutting position is changed in a state in which

[0011]

According to the method of forming a tailored blank material having a different thickness according to the present invention, different types of plate materials having different thicknesses and strengths are butt-joined and used as a material of a component in which the direction of overhanging the plate material changes depending on the portion. when forming a different thickness tailored blank, the thin plate side plate member is plate thickness t ₂ a and a tensile strength F _2, when plank plate material is and a tensile strength F ₃ a plate thickness t _3, stretch forming force Butting step d of the plate material on the side where Since the joint is formed at the butt position to meet the thickness, the butt step on the side where the overhang forming force is applied to all the parts of the tailored blank material having the thickness difference becomes less than the specified value. Therefore, the disadvantage that the butting step of the sheet material on the overhang forming side becomes large and a large shearing force is applied at the time of press forming is eliminated, and the press forming is favorably performed without breaking the joint portion, and depending on the part, It is to be formed in a differential thickness tailored blank material suitable as a material of a part whose overhang forming direction changes, improving the forming performance of the differential thickness tailored blank material, and increasing the range of applicable parts,
A non-defective tailored blank material having a high yield rate and significantly improving the yield is formed.

The differential thickness tailored blank material according to the present invention is a differential thickness tailored blank material which is used as a material for a part in which different types of plate materials having different thicknesses and strengths are butt-joined and joined, and the direction in which the sheet material is stretched varies depending on portions. in, the thin plate side plate member is plate thickness t ₂ a and a tensile strength F _2,
When the thick plate-side plate has a plate thickness t ₃ and a tensile strength F ₃ , the butting step d of the plate on the side where the overhang forming force is applied is:
always, Since the butting position is changed in the state of meeting the condition, the butting step on the side where the overhang forming force is applied to all parts of the differential thickness tailored blank material is less than the specified value, The problem that the butt step of the sheet material on the overhang forming side becomes large and a large shear force is applied at the time of press forming is eliminated, and the press forming is performed satisfactorily without breaking the joint, and the overhang forming of the sheet material depending on the part It becomes a tailored blank material suitable as a material for parts that change direction, improving the molding performance of differential thickness tailored blank material, increasing the range of applicable parts, increasing the yield rate, and significantly improving the yield. It becomes a tailored blank material with a different thickness.

[0013]

According to the method of forming a tailored blank having a different thickness according to the present invention, different types of plates having different thicknesses and strengths are butt-joined and joined, and as a material of a part whose bulging direction changes depending on the portion. In forming the differential thickness tailored blank material to be used, the thin side plate material has a thickness t _2.
And the tensile strength F ₂ , and when the thick plate side plate has a thickness t ₃ and the tensile strength F ₃ , the butting step d of the plate on the side where the overhang forming force is applied is always Since the joint is formed at the butt position to meet the thickness, the butt step on the side where the overhang forming force is applied to all the parts of the tailored blank material having the thickness difference becomes less than the specified value. As a result, the conventional problem of large shearing force during press forming due to a large butting step of the sheet material on the overhang forming side can be eliminated, and the press forming can be performed well without breaking the joint. It becomes possible to form a tailed blank material with a thickness difference suitable as a material of a part in which the overhang forming direction of the plate material changes depending on the part, and it is possible to improve the molding performance of the tailored blank material with a thickness difference, applicable It is possible to increase the range of parts,
A remarkable effect is obtained that it is possible to increase the non-defective product rate and to form a tailored blank material having a difference in thickness with significantly improved yield.

According to the differential thickness tailored blank material according to the present invention, a differential thickness tailored blank is used as a material for a part in which different types of plates having different thicknesses and strengths are butt-joined and joined, and the direction of the overhanging of the plate varies depending on the portion. in the blank, thin side plate is the plate thickness t ₂ a and a tensile strength F _2, when plank plate material is a plate thickness t ₃ a and a tensile strength F _3, the consuming bulging force side of the plate Butt step d
But always Since the butt position is changed in the state of meeting the difference, since the butt step on the side where the overhang forming force is applied to all parts of the differential thickness tailored blank material is less than the specified value, It is possible to eliminate the conventional disadvantage that the butt step of the sheet material on the overhang forming side becomes large and a large shear force is applied at the time of press forming, and it is possible to perform the press forming well without breaking the joint, Tailored blank material suitable as a material for parts whose overhang forming direction changes depending on the part can be made, it is possible to improve the forming performance of tailored blank material with a different thickness, and the range of applicable parts is increased Thickness tailored blank material that has been able to increase the yield rate as well as the yield rate Leads to significantly better effect can be provided.

[0015]

Next, a method of forming a differential thickness tailored blank material and an example of a differential thickness tailored blank material according to the present invention will be described, but it goes without saying that the present invention is not limited to only such examples. Absent.

FIG. 1 is an explanatory sectional view showing the definition of the butting position of different kinds of sheet materials according to the present invention.

In FIG. 1, reference numeral 1 denotes a differential thickness tailored blank, 2 denotes a thin side plate of the differential thickness tailored blank 1, 3 denotes a thick side plate of the differential thickness tailored blank 1, and 4 denotes a differential thickness tailored blank. The joint portions 5 of the material 1 are recessed portions such as embosses in the differential thickness tailored blank material 1.

The thin plate 2 has a thickness t ₂ and a tensile strength F ₂ , and the thick plate 3 has a thickness t ₃ .
Has a tensile strength F _3, which is intended to butt step d is formed at the junction 4 in the plate material.

FIG. 2 shows an embodiment of a method for forming a tailored blank having a thickness different from that of the present invention, and an embodiment of a tailored blank having a thickness different from that shown in FIG. In this case, the overhang forming direction A of the plate material on the joining portion 4 is the direction shown in FIG.

In the case of the differential thickness tailored blank material 1 formed into a hat-shaped (hat-shaped) part, the bulging force is usually applied to the plate material in the bulging direction indicated by an arrow A upward from the inside of the hat. However, in the recess-shaped portion 5 such as the emboss, a bulging force is applied in the bulging direction indicated by the downward arrow A from the outside of the hat mold.

Therefore, the recessed portion 5 such as the emboss
In the portion excluding, the plate members 2 and 3 are joined so that the step d of the plate material inside the hat shape at the joint portion 4 is equal to or less than a specified value, and there is a recessed portion 5 such as an emboss. At the joints, the plate members 2 and 3 are joined so that the step difference d between the plate members outside the hat shape at the joint portion 4 is equal to or less than a specified value.

Regarding the specified value of the butting step d of the plate material,
It is clear from experiments at the specimen level.

At the time of the experiment, the thickness t was 1.
2 mm to 2.3 mm and tensile strength F of 38 kgf / m
Experiments were performed from m ² grade with 55 kgf / mm ² grade mild steel plate. Further, welding was performed by CO ₂ laser for joining. Furthermore, the evaluation of the overhang molding was performed by a ball head overhang test.

FIG. 4 shows the results of this experiment. In FIG. 4, the non-defective rate on the vertical axis ranges from n = 10 to n under each condition.
= 20 and an evaluation experiment was performed.
The calculation is performed as G. Regarding the abutment position on the horizontal axis, the abutment position = 0 and the abutment step d on the molding direction side
It is assumed that as the value of the butting position increases in the state of = 0, the butting step d on the molding direction side increases.

As shown in FIG. 4, when the butting step d in the molding direction becomes large, the shearing force applied to the joint at the time of press molding increases, so that the joint tends to be broken and molding of the part becomes impossible. Becomes And according to the experimental results, , The non-defective rate was 100%, but when it exceeded 0.5, a remarkable decrease in the non-defective rate was recognized. From this result, the specified value of the butting step d of the plate material is It was found that it was better to be.

In the case of manufacturing a hat-shaped press-formed product as in this embodiment, the overhanging force at the time of press-forming is indicated by the overhang-forming direction A from the outside of the hat mold at the recessed portion 5 such as an emboss. In the other parts, it works in the direction indicated by the overhang forming direction A from the inside of the hat mold.

Therefore, for all the joints, the butting step on the side where the overhang forming force is applied is determined. By doing so, it becomes possible to suppress the shearing force applied to the joint at the time of press molding and to suppress the breakage at the joint.

[Brief description of the drawings]

FIG. 1 is a cross-sectional explanatory view showing a definition of a butting position (butting step d) in a method for forming a differential thickness tailored blank material and a differential thickness tailored blank material according to the present invention.

FIG. 2 is an explanatory view of a slope showing an example of a method of forming a differential thickness tailored blank material according to the present invention and an example of the differential thickness tailored blank material.

FIG. 3 is an explanatory side view showing a stretch forming direction A in an example of a method for forming a differential thickness tailored blank material and an example of the differential thickness tailored blank material according to the present invention.

FIG. 4 is a graph showing a method of forming a differential thickness tailored blank material according to the present invention and experimental results supporting the size of a butt step defined in the differential thickness tailored blank material.

FIG. 5 is an explanatory view of a slope of a differential thickness tailored blank material according to a conventional example.

FIG. 6 is an explanatory side view showing a stretch forming direction A in a differential thickness tailored blank material according to a conventional example.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Different thickness tailored blank material 2 Thin plate side plate material 3 Thick plate side plate material 4 Joint part of differential thickness tailored blank material 1 5 Depression shape part such as embossing t ₂ Sheet thickness of thin plate side plate F ₂ Tensile strength of thin plate side plate t ₃ Thickness of thick side plate F ₃ Tensile strength of thick side plate d Butt difference of plate A A Direction of overhang forming of plate

Claims (2)

[Claims] When a different thickness tailored blank material used as a material of a part in which different types of plate materials having different thicknesses and strengths are butt-joined and the bulging direction of the plate material changes depending on a portion is formed, a thin side plate material is used. a plate thickness t ₂ a and a tensile strength F _2, when plank plate material is a plate thickness t ₃ a and a tensile strength F _3, butt step d of the plate in such a stretch forming force side is always A method of forming a differential thickness tailored blank material by joining at abutting position to form a differential thickness tailored blank material. 2. A tailored blank material having a difference in thickness and strength, which is used as a material for a part in which different types of plate materials having different thicknesses and strengths are butt-joined and the direction in which the overhang of the plate material changes depending on a portion are different from each other. ₂ and tensile strength F
₂ , when the thick plate side plate has a plate thickness t ₃ and a tensile strength F ₃ , the butting step d of the plate member on the side where the overhang forming force is applied is always A tailored blank having a different thickness, wherein the abutting position is changed in a state of satisfying.