JP2000015356A - Formation of cylindrical member having branch pipe - Google Patents

Abstract

PROBLEM TO BE SOLVED: To efficiently form a bulging part without enlarging the size of equipment and to improve the quality of products. SOLUTION: A hollow work 7, which is primarily formed by variable extrusion so that the cross section shape of a section 8 becoming a branch pipe is partially varied and its circumferential length becomes longer than that of a general part 9, is set within a forming die 10 which is diesunk corresponding to a shape of a product. Thereafter, pressure is applied to the inside of the work 7, the section 8 becoming the branch pipe is bulged into a branch pipe forming part 10a within the forming die 10 and whereby a bulging part is secondarily formed in the work 7.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for forming a tubular member such as a pipe part or a joint used for a vehicle body structure. The present invention relates to a method of forming a tubular member having a branch pipe in which a part of a work is protruded to form a bulge portion by applying a pressure.

[0002]

2. Description of the Related Art As is well known, for example, tubular members made of aluminum or the like have been widely used for pipe parts, joints used for vehicle body structures, and the like. When the pipe is provided, the following molding method may be adopted.

This will be described with reference to FIGS. 12, 13 and 14. First, a work 1 having a hollow and uniform round cross section is first formed by a not shown extruder using a round tube material such as aluminum. As shown in FIG. 12, the work 1 is set in a mold 2. Here, in order to form the bulging portion 3 (shown in FIG. 13) which will be a branch pipe on the work 1, the molding die 2 is made of a product including a square branch pipe forming portion 2a corresponding to the branch pipe portion. It is engraved according to the shape of a square tubular member 6. Then, as shown in FIG. 13, water or the like is applied to the inside of the work 1 while applying a compressive force with the piston 4 or the like in the axial direction of the work 1 from both ends of the work 1 so that the bulging portion 3 does not crack. The secondary molding is performed by filling and applying pressure to push the material into the branch pipe forming portion 2a. Then, the material flows into the branch pipe forming portion 2a of the molding die 2, and the bulging portion 3 having a height sufficient to form the branch pipe 5 is formed therein. Therefore, as shown in FIG. By processing the part 3 separately, a square tubular member 6 having a square branch pipe 5 can be obtained.

[0004]

However, in the above-mentioned conventional method for forming the cylindrical member 6, the material is poured into the branch pipe forming portion 2a by the axial compressive force acting on the work 1, and the bulging portion is formed. 3, the length of the workpiece 1 inevitably decreases in the longitudinal direction. Therefore, it is necessary to previously set the length of the work 1 to be longer in consideration of the decrease in the length of the work 1, and thus there is a problem that the size of the molding die 2 is increased.

On the opposite side of the bulging portion 3, wrinkles are apt to be generated due to excess material, and if the wrinkles are to be suppressed, the amount of pushing of the work 1 in the axial direction must be reduced. 3 cannot secure the required height. Therefore, the present invention provides a method of forming a tubular member having a branch pipe, which can efficiently form a bulging portion and increase product quality without increasing the size of the apparatus.

[0006]

In order to solve the above-mentioned problems, in the present invention, the cross-sectional shape of a portion to be a branch pipe is partially changed so that the peripheral length thereof is longer than that of a general portion by variable extrusion. The primary molded work is set in a molding die engraved corresponding to the product shape, and then a pressure is applied to the inside of the workpiece to project the branch pipe portion into a space in the molding die, thereby forming the work. By performing the secondary molding for forming the bulging portion, the load on the bulging portion that changes in the direction in which the circumferential length extends in the secondary molding for forming the bulging portion is reduced. Enables easy forming of the protrusion.

[0007] Further, a work primarily formed by variable extrusion such that the cross-sectional shape of a portion to be a branch pipe is made thicker than that of a general portion is carved in accordance with the product shape. When set in a molding die, then apply pressure to the inside of the work, and then perform the secondary molding of forming the branch pipe into a space in the molding die to form a bulge on the work. In the secondary molding for forming the bulging portion, the margin of the bulging portion that changes in the direction in which the wall thickness becomes thinner is improved until the rupture of the bulging portion is reduced, and the burden on the bulging portion is reduced. Enables easy molding.

In the case where a hollow workpiece having a plurality of branch pipe portions is formed in a primary forming step, a branch pipe portion in which a molding height of a swollen portion is not sufficiently obtained in the secondary forming step. By making the perimeter of the pipe longer than the other branch pipes in advance, the branch pipe sections and the other branch pipe sections that do not have sufficient swelling height during secondary molding are obtained. And the swelling height is the same. Further, when the primary work is performed on a hollow workpiece having a plurality of the branch pipe portions formed thereon, the height of the bulging portion is not sufficiently obtained during the secondary molding. By making the wall thickness thicker than other branch pipes in advance, it is possible to obtain a branch pipe that does not have sufficient swelling height during secondary molding and a branch pipe Have the same bulging height.

Further, when a workpiece having a plurality of branch pipes formed thereon is primarily formed, a cross-section of the branch pipe becomes closer to the center in the longitudinal direction of the tubular member than to the end of the work. Focusing on the fact that the longer the circumferential length is, the further away from the end of the work, the higher the swelling height cannot be obtained due to loss of pressure, etc. The above-mentioned peripheral length of the portion to be set is set to be long beforehand to cope with the problem. In the case where the work in which a plurality of the branch pipes are formed is primarily formed, the thickness of the cross-section of the branch pipe increases as the distance from the end of the work toward the center in the longitudinal direction of the tubular member increases. With the setting, paying attention to the fact that the further away from the end of the work, the more the bulging height is not obtained, the thickness of the portion of the branch pipe where the bulging height is not obtained is increased in advance. To deal with.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A first embodiment of the present invention will be described below with reference to FIGS. First, as shown in FIG. 1, a work 7 having a square hollow cross-sectional shape is primarily formed by an extrusion molding device (not shown) using a square tube molding material such as aluminum or an aluminum alloy. The extrusion in this case is a variable cross-section extrusion, as shown in FIG.
The cross-sectional shape (shown in FIG. 3) of the portion 8 to be a branch pipe is partially changed, and the circumferential length is the cross-sectional shape of the general portion 9 (shown in FIG. 2).
The work 7 is primarily formed by swelling so as to be longer than the work 7.

Next, as shown in FIG. 4, the work 7 is set in a molding die 10. Here, in order to form the bulging portion 11 in the portion 8 serving as a branch pipe of the workpiece 7, a forming die 10 is formed.
Is engraved according to the shape (square cross-sectional shape) of the tubular member 12 (shown in FIG. 6) as a product including the square branch pipe forming portion (space portion) 10a corresponding to the branch pipe portion 8. ing. Then, as shown in FIG. 5, the work 7 is filled with a liquid such as water, for example, and the secondary molding (bulge processing) of applying pressure from both ends of the work 7 into the work 7 is performed. Since the peripheral portion of the branch 8 has a long circumference in advance, the portion 8 protrudes with a sufficient margin into the branch tube forming portion 10a of the molding die 10, and therefore has a desired height here. The swollen portion 11 is formed.

At this time, since the circumferential length of the bulging portion 11 has been increased in advance, the material can smoothly flow from this portion to the branch pipe forming portion 10a of the molding die 10 so as to protrude. No crack occurs in 11. Also, no wrinkles are generated on the opposite side of the bulging portion 11. Therefore, there is no need to press the end of the work 7 as in the related art, and it is not necessary to increase the length of the work 7 in advance.
The molding die 10 can be reduced in size as compared with the related art.
Then, after the completion of the secondary molding, the bulging portion 11 is post-processed to obtain a square tubular member 12 having a square branch pipe 13 as shown in FIG.

Next, a second embodiment of the present invention will be described with reference to FIGS. In this embodiment, as shown in FIGS. 7 and 8, the hollow workpiece 14 primarily formed by extrusion molding partially changes the cross-sectional shape (shown in FIG. 8) of a portion 15 to be a branch pipe. It is primarily formed by variable extrusion so that the wall thickness is larger than the general portion 16. Here, the work 14 is extruded using a square tube material. This work 14
Is set in a molding die 10 engraved corresponding to the product shape in the same manner as in the first embodiment, and thereafter, when pressure is applied in the work 14, the branch pipe is formed as shown in FIG. The portion 15 gradually becomes thinner, and the excess material flows into the rectangular branch pipe forming portion 10a in the molding die 10 without any load and without any load, and projects, forming a bulging portion 17 having a desired height on the workpiece 14. Then, the work 14 is secondary formed. Also in this embodiment, since the excess material in the portion 15 to be the branch pipe flows into the branch pipe forming portion 10a of the molding die 10 and the bulging portion 17 is formed, the direction in which the wall thickness becomes thinner in the secondary forming. The degree of leeway up to breaking of the bulging portion 17 that changes to
7 does not crack, and no wrinkles occur on the side opposite to the bulging portion 17.

Next, a third embodiment of the present invention will be described with reference to FIG.
0 and FIG. In this embodiment, a cylindrical member having a plurality of branch pipes at the same height is formed. As shown in FIG. 10, a hollow workpiece 18 primarily formed by extrusion molding is formed by partially changing the cross-sectional shape of a plurality of (here, three) branch pipes 19, 19, and 20. It is primarily formed by variable extrusion so that the thickness is larger than the general portion 21. In this case, a portion 20 to be a branch pipe at the center in the longitudinal direction is formed with a higher forming height than a portion 19 to be a branch pipe on the end side of the work 18. That is, when the part 20 which becomes the branch pipe at the center cannot produce a bulging height at the time of secondary molding from the end side from the point that the greater the distance from the end of the work 18 becomes, the greater the loss of pressure becomes. Is to give a certain molding height in the first molding in advance. By doing so, FIG.
As shown in FIG. 1, when secondary molding is performed with the molding die 100,
Each of the bulging portions 22, 23, 23 can be formed at the same height.

In this embodiment, the case where three branch pipe portions 19, 19 and 20 are formed has been described. However, when there are about three branch pipe portions, the central portion side The portion 20 which becomes the branch pipe of the present invention can obtain a swelling height almost equal to that of the other portions without giving a height in advance, so that there is not much problem. Is effective when there are five or more sites serving as branch pipes. In such a case, the work can be formed by gradually increasing the forming height of the branch pipe portion from the end to the center of the work. Further, in this embodiment, the work 18 which is primarily formed is a branch pipe 19, 19, 2.
Although the peripheral length in the cross section of the portion which becomes 0 was formed longer, this portion was made thicker than the general portion as in the second embodiment, and was gradually increased toward the central portion in the longitudinal direction of the work 18. When the wall thickness is increased, the same effect as when the peripheral length is increased can be obtained.

The present invention is not limited to the above-described embodiment. For example, the branch pipe may have a longer cross-sectional circumference and a thicker section. Good. Further, the present invention is not limited to the case where the branch pipes are provided in alignment as in the third embodiment, and a swelling height can be obtained in the secondary molding due to the shape of the branch pipe. In the case of a portion that does not exist, the peripheral length in the cross section or the wall thickness can be increased in advance in the primary molding.

[0017]

As described above, according to the present invention, the bulging portion is formed by first forming the work so as to increase the circumferential length in the cross section of the portion which will later become the branch pipe. In the case of secondary molding, the burden on the bulging portion, which changes in the direction in which the circumferential length extends, can be reduced, and natural molding can be performed, and the molding height of the bulging portion can be increased and the product quality can be improved. There is an effect that can be. Therefore, it is not necessary to increase the length of the work in order to secure the pushing amount of the work as in the related art, and there is an effect that the size of the molding die can be reduced. In addition, by forming the work primarily so as to increase the thickness in the cross section of the part that will later become a branch pipe, the thickness changes in the direction of decreasing the thickness during the secondary forming to form the bulging part The degree to which the bulging portion breaks can be improved, and the load on the bulging portion can be reduced, so that reasonable molding is possible. Therefore, as a result, the molding height of the swollen portion can be increased, the product quality can be enhanced, and there is an effect that the molding die can be reduced in size similarly to the above.

In the case where a hollow workpiece having a plurality of branch pipes is formed in a primary molding, a branch pipe in which a molding height of a swollen portion is not sufficiently obtained during the secondary molding. By making the perimeter of the pipe longer than the other branch pipes in advance, the branch pipe sections and the other branch pipe sections that do not have sufficient swelling height during secondary molding are obtained. This has the effect of making the swelling heights equal to each other. Further, when the primary work is performed on a hollow workpiece having a plurality of the branch pipe portions formed thereon, the height of the bulging portion is not sufficiently obtained during the secondary molding. By making the wall thickness thicker than other branch pipes in advance, it is possible to obtain a branch pipe that does not have sufficient swelling height during secondary molding and a branch pipe This has the effect of making the swelling heights equal.

Further, in the case where the work having a plurality of branch pipe portions formed thereon is primarily formed, a cross-section of the branch pipe portion becomes closer to the center in the longitudinal direction of the tubular member than the end portion of the work. Focusing on the fact that the longer the circumferential length is, the more the further away from the end of the work, the more the swelling height cannot be obtained. By setting the circumferential length to be longer in advance, there is an effect that the bulging height of each branch pipe can be made equal. In the case where the work in which a plurality of the branch pipes are formed is primarily formed, the thickness of the cross-section of the branch pipe increases as the distance from the end of the work toward the center in the longitudinal direction of the tubular member increases. With the setting, paying attention to the fact that the further away from the end of the work, the more the bulging height is not obtained, the thickness of the portion of the branch pipe where the bulging height is not obtained is increased in advance. In this case, there is an effect that the swelling height of each branch pipe can be made equal.

[Brief description of the drawings]

FIG. 1 is a perspective view of a primary molded work according to a first embodiment of the present invention.

FIG. 2 is a sectional view taken along line AA of FIG.

FIG. 3 is a sectional view taken along line BB of FIG. 1;

FIG. 4 is an explanatory diagram in which the work of FIG. 1 is set in a molding die.

FIG. 5 is an explanatory diagram for secondary forming a work from the state of FIG. 4;

FIG. 6 is a perspective view of a tubular member.

FIG. 7 is a perspective view of a primary molded work according to a second embodiment of the present invention.

FIG. 8 is a sectional view taken along line CC of FIG. 7;

FIG. 9 is an explanatory diagram in which the work of FIG. 7 is set in a molding die.

FIG. 10 is a front view of a work that is primarily formed according to a third embodiment of the present invention.

FIG. 11 is an explanatory view of the work of FIG. 10 set on a molding die.

FIG. 12 is an explanatory diagram in which a work of the related art is set in a molding die.

FIG. 13 is an explanatory diagram for secondary forming a work from the state of FIG. 12;

FIG. 14 is a perspective view of a conventional tubular member.

[Description of Signs] 7, 14, 18 Work 8, 15, 19, 20 Portion to be a branch pipe 9, 16, 21 General part 10, 100 Mold 10a Branch pipe formation part (space part) 11, 17, 22, 23 bulging part 12 cylindrical member 13 branch pipe

Claims (6)

[Claims] 1. A hollow workpiece primarily formed by variable extrusion so that the cross-sectional shape of a portion to be a branch pipe is partially changed so that its peripheral length is longer than that of a general portion, is formed according to the product shape. It is set in the engraved molding die, and thereafter, pressure is applied to the inside of the work, and the portion to be the branch pipe is extended to a space in the molding die to perform secondary molding for forming a bulging portion on the work. A method for forming a cylindrical member having a branch pipe. 2. A hollow workpiece primarily formed by variable extrusion so that the cross-sectional shape of a portion to be a branch pipe is partially changed so that the wall thickness becomes larger than that of a general portion is formed in accordance with the product shape. It is set in the engraved molding die, and thereafter, pressure is applied to the inside of the work, and the portion to be the branch pipe is protruded into a space in the molding die to perform secondary molding of forming a bulging portion on the work. A method for forming a cylindrical member having a branch pipe. 3. When a hollow workpiece having a plurality of branch pipe portions formed therein is primarily formed, a branch pipe which does not have a sufficient height of a bulging portion during the secondary forming. The method for forming a tubular member according to claim 1, wherein the peripheral length of the part to be formed is made longer than the part to be the other branch pipe in advance. 4. When a hollow workpiece having a plurality of portions serving as branch pipes is formed by primary forming, a branch pipe which does not have a sufficient molding height of a bulging portion during the secondary forming. The method for forming a tubular member according to claim 2, wherein the thickness of the portion to be formed is made thicker in advance than the portion to be another branch pipe. 5. A primary section of a work having a plurality of branch pipe portions formed therein, wherein a cross-section of the branch pipe portion becomes closer to the longitudinal center portion of the tubular member than the end portion of the work. The method for forming a tubular member having a branch pipe according to claim 1, wherein the circumferential length of the cylindrical member is set long. 6. A primary section of a work having a plurality of branch pipe portions formed therein, wherein a cross section of the branch pipe portion becomes closer to a central portion in the longitudinal direction of the tubular member than to an end portion of the work. 3. The method for forming a tubular member having a branch pipe according to claim 2, wherein the wall thickness is set thick.