JP3686031B2 - Method for manufacturing hollow member - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a method for producing a hollow member having a cross-sectional plate thickness orthogonal to the longitudinal direction and a method for producing a hollow member having a cross-sectional shape orthogonal to the longitudinal direction.
[0002]
[Prior art]
Generally, metal hollow members are used as component parts in industrial equipment, transportation equipment, and the like. For example, in automobiles, they are widely used as frame members such as body frames and door frames.
[0003]
By the way, in recent years, due to demands for environmental measures, recycling, resource saving, weight reduction, etc., the hollow member can freely control the plate thickness and cross-sectional shape in the longitudinal direction outside using a lightweight material such as aluminum material, Development of a tubular member having an optimal plate thickness distribution with reduced waste and a hollow member having an optimal cross-sectional shape in the longitudinal direction is desired.
[0004]
For example, as disclosed in JP-A-5-76950 and Japanese Patent No. 2874467, after heating a predetermined portion of an equal thickness tubular material, the tubular material is compressed in the longitudinal direction to increase the thickness of the heating part. A hollow member manufacturing method is already known in which a hollow member having a different cross-sectional shape in the longitudinal direction is obtained.
[0005]
[Problems to be solved by the invention]
However, in such a conventional method, since the tubular material is compressed from the longitudinal direction,
(1) There is a risk of buckling or falling of the tubular material.
[0006]
{Circle around (2)} It is difficult to make the tubular material have a constant circumference over its entire length.
[0007]
For this reason, there is a problem that a high-precision product cannot be obtained.
[0008]
The present invention has been made in view of such circumstances, and has a desired plate thickness distribution in the longitudinal direction, a hollow member having a constant circumferential length without a constricted portion or a bulging portion, or a sectional shape in the longitudinal direction. It is an object of the present invention to provide a novel method for producing a hollow member, which can easily produce different hollow members.
[0009]
[Means for Solving the Problems]
The invention according to claim 1 is a method of manufacturing a hollow member having a cross-sectional plate thickness orthogonal to the longitudinal direction, the longitudinal direction being different,
A heating step of heating the tubular material with a temperature difference in the longitudinal direction thereof, and a tensioning step of applying an internal pressure to the tubular material heated in the step to pull the tubular material in the axial direction. According to such a feature, it is possible to manufacture a hollow member with a variable cross-sectional plate thickness in the longitudinal direction, and in particular, by applying an internal pressure to the tubular material and pulling it in the axial direction, ”Does not occur, and a hollow member having a substantially equal circumferential length can be easily and accurately manufactured.
[0010]
The invention according to claim 2 is a method for manufacturing a hollow member having a cross-sectional shape orthogonal to the longitudinal direction, which is different in the longitudinal direction.
A heating process for heating the tubular material with a temperature difference in its longitudinal direction, a tensioning process for applying an internal pressure to the tubular material heated in the process and pulling the tubular material in the axial direction, and a longitudinal process in the process. An expansion tube forming step in which an elongated tubular material whose cross-sectional plate thickness in a direction orthogonal to the direction is changed in the longitudinal direction thereof is set in the cavity of the mold, and an internal pressure is applied to the elongated tubular material to expand the tube. According to such a feature, hollow members having different cross-sectional shapes in the longitudinal direction can be manufactured. In particular, the tubular material is partially “necked” by pulling in the axial direction by applying an internal pressure. The hollow member having the substantially equal circumferential length over the entire length can be easily and accurately manufactured.
[0011]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the present invention will be specifically described below based on the embodiments of the present invention illustrated in the accompanying drawings.
[0012]
First, the first embodiment of the present invention will be described with reference to FIGS. FIG. 1 is a perspective view of a hollow member manufactured by the manufacturing method of the present invention, FIG. 2 is a diagram showing a manufacturing process for manufacturing a hollow member from a tubular material, and FIG. 3 is a partial current heating, a whole current heating, and an interior FIG. 4 is a cross-sectional view of the internal pressurization and tension forming apparatus, and FIG. 5 is a cross-sectional view of the tube expansion (bulge) forming apparatus.
[0013]
In the first embodiment, aluminum alloy, the same cross-sectional plate thickness in the longitudinal direction, and the cross-sectional plate thickness in the longitudinal direction is variably controlled from an equal-diameter tubular material Pa. This is a case of manufacturing a hollow member having a tube expansion part having substantially the same cross-sectional plate thickness.
(1) Partial energization heating process of tubular material Pa (2) Entire energization heating process of tubular material Pa (3) Internal pressurization and tension forming process in which internal pressure is applied to tubular material Pa to pull in axial direction (4) Tensile molding It consists of a tube expansion (bulge) forming step of the elongated tubular material Pb later, and these steps will be described in order below.
[0014]
[(1) Partial energization heating process for tubular material Pa] (See (1) in FIG. 3)
An aluminum alloy tubular material Pa having the same cross-sectional plate thickness and the same cross-sectional shape in the longitudinal direction is partially heated in the longitudinal direction by a heating means, for example, an electric heating means HE. That is, the positive electrode portion 30 and the negative electrode portion 31 of the energization heating means HE are conductively connected to both ends of the tubular material Pa, and the current bypass means BP is arranged on the outer peripheral surface of the intermediate portion of the tubular material Pa. Established. This current bypass means BP has two low resistance conductors (for example, copper bodies) 32 and 33 having an electrical resistance smaller than that of an aluminum alloy at an interval in the longitudinal direction at an intermediate portion in the longitudinal direction of the tubular material Pa. Conductive connection is made so as to surround it, and the low resistance conductors 32 and 33 are connected to each other by a conductive wire 34.
[0015]
The tubular material Pa is provided with sealing members 36 and 37 for sealing both the left and right open ends, and the internal pressure is applied to the tubular material Pa in the subsequent internal pressurization and tensile forming processes on both sides in the axial direction. Is provided with an internal pressurizing means PR for applying pressure and a pulling means PL for pulling it in the axial direction. The internal pressurization means PR includes an internal pressurization source 50 for pumping pressurized air into the tubular material Pa, and a pressurization circuit 51 that communicates the internal pressurization source 50 with the inside of the tubular material Pa. The pressurized air is pumped from the pressurizing circuit 51 through the one sealing member 35 into the tubular material Pa. The pulling means PL is composed of a pulling actuator connected to a sealing member 36 provided at the other end of the tubular material Pa, that is, a pulling cylinder 37. According to the operation of the pulling cylinder 37, the tubular material Pa is formed. Is pulled in its longitudinal direction.
[0016]
When the energization heating means HE is energized, the current flows from the tubular material Pa to the tubular material Pa again through the current bypass means BP. That is, the two low resistance conductors 32 and 33 have two electric resistance values smaller than that of the tubular material Pa made of aluminum alloy, so that the two low resistance conductors are shown in FIG. The tubular material Pa flows around the hollow portion N of the tubular material Pa corresponding to between 32 and 33. Accordingly, the tubular material Pa is heated at both side portions S, S in the longitudinal direction, and the calorific value is relatively larger than that at the intermediate portion N.
[0017]
In the partial energization heating process, the internal pressurizing means PR and the pulling means PL do not operate.
[0018]
[(2) Whole energization heating process of tubular material] (Refer to (2) in FIG. 3)
In the previous step, when the both side portions S, S are heated to a temperature higher than the intermediate portion N by partial heating of the tubular material Pa, the operation of the current heating means HE is continued while the current bypass means BP The two low resistance conductors 32 and 33 are separated from the tubular material Pa. As a result, the positive electrode 30 and the negative electrode 31 of the energization heating means HE are energized through the entire length of the tubular material Pa, and the current flows through the tubular material Pa as shown by the arrow b in FIG. The tubular material Pa is heated by energization over its entire length. Therefore, by the two steps, the left and right side portions S, S of the tubular material Pa are heated to a high temperature, for example, higher than the recrystallization temperature (500 ° C.) of the tubular material Pa, while the intermediate portion of the tubular material Pa. N is heated to a lower temperature than them.
[0019]
Note that the internal pressurizing means PR and the pulling means PL of the tubular material Pa do not operate even in this overall energization heating process.
[0020]
[(3) Internal pressurization and tensile forming process of tubular material Pa] (See FIG. 3 (3) and FIG. 4)
In the above process, the tubular material Pa is in a state in which the left and right side portions S, S and the intermediate portion N thereof are heated with a predetermined temperature difference. A predetermined tension is applied to the tubular material Pa in the axial direction by the operation of the pulling means PL while feeding the tubular material Pa into the tubular material Pa and applying a predetermined internal pressure to the tubular material Pa. Thereby, the tubular material Pa extends in the axial direction while a predetermined internal pressure is applied to the inside thereof. At this time, the left and right end portions S, S heated to a high temperature are stretched quickly and increase in elongation because the deformation resistance is small, whereas the intermediate portion N heated to a lower temperature is deformed more than that. Since resistance is large, it grows slowly and its elongation is small. Further, during this tensioning process, the tubular material Pa is supplied with pressurized air from the internal pressurizing means PR and is applied with a predetermined internal pressure. No “necking” occurs, and the circumference is kept substantially constant over its entire length.
[0021]
As a result, as shown in FIGS. 2 (C) and 4, the cross-sectional plate thickness of the elongated tubular material Pb stretched in the axial direction is that the hollow portion N is thick, that is, 1.25 t, and its left and right side portions The cross-sectional plate thicknesses of S and S are thinner than the hollow portion N, that is, t, the cross-sectional plate thickness is variably controlled, and there is no “necking”, and an elongated tubular material Pb having a substantially equal circumferential length is provided. can get.
[0022]
[(4) Tube expansion forming (bulge forming) process of elongated tubular material Pb after tensile forming] (see FIG. 5)
The elongated tubular material Pb which is elongated in the axial direction in the previous step and has substantially the same circumferential length is conveyed to a tube expansion molding (bulge molding) device by an appropriate conveying means.
[0023]
As shown in FIG. 4, the mold M of the tube expansion molding (bulge molding) apparatus includes a fixed mold fixed on the base 1, that is, a lower mold 2, and a movable mold for these fixed molds, That is, it is composed of the upper mold 3, and an elevating cylinder 4 is connected on the mold M, and the upper mold 3 is moved up and down by the expansion and contraction operation of the lifting cylinder 4.
[0024]
The mold M is stretched in the axial direction in the above process and is still held in a heated state (about 500 ° C.), and is subjected to hot tube expansion (hot bulge) above the recrystallization temperature of the elongated tubular material Pb. The mold M is heated to about 500 ° C. by heating means (not shown).
[0025]
A lower mold forming surface 2m for forming the lower half of the elongated tubular material Pb is formed on the upper surface of the lower mold 2, and an upper half of the elongated tubular material Pb is formed on the lower surface of the upper mold 3. An upper mold molding surface 3m for molding the portion is formed, and when the mold M is clamped, the cavity 5 is formed by the molding surfaces 2m and 3m. Hold means H for fixing both end portions of the elongated tubular material Pb are provided on the left and right sides of the mold M. The holding means H includes left and right holders 6 and 7 on the left and right sides of the mold M, and these holders 6 and 7 can move forward and backward with respect to the mold M and are provided on the base 1. Movement on the guides 8 and 9 is controlled by the operation of the actuators 10 and 11. As the left and right holders 6 and 7 are advanced, both end portions of the elongated tubular material Pb are fitted and fixed in the support holes 6 a and 7 a of the left and right holders 6 and 7.
[0026]
Further, on both the left and right sides of the mold M, pressing means PU for pressing the elongated tubular material Pb set therein from the axial direction is provided. The pressing means PU has left and right pressing cylinders 12 and 13, and the pressing members 16 and 17 fixed to the tip portions of the rod portions 12 r and 13 r of these pressing cylinders 12 and 13 are the left and right holders 6 and 6. 7 is inserted into the support holes 6a and 6b so as to be able to advance and retreat. According to the extending operation of the left and right pressing cylinders 12 and 13, the distal ends of the pressing members 16 and 17 are respectively engaged with both ends of the elongated tubular material Pb. The elongate tubular material Pb can be pressed in the axial direction from both ends by the forward operation of the pressing members 16 and 17 that follow.
[0027]
O-rings 19 and 20 as sealing means S are provided between the left and right pressing members 16 and 17 and the support holes 6a and 7a, and between the support holes 6a and 7a and the outer peripheral surfaces of both ends of the elongated tubular material Pb, respectively. The O-rings 19 and 20 are fluid-tightly sealed between the elongated tubular material Pb and the holders 6 and 7 and the pressing members 16 and 17 when the pressing members 16 and 17 are engaged with the elongated tubular material Pb. can do.
[0028]
Compressed air supply means A for pressurizing the inside of the elongated tubular material Pb is provided on both the left and right sides of the mold M1. This compressed air supply means A pumps compressed air from the compressed air supply source 22 to the sealed hollow portion of the elongated tubular material Pb through the compressed air circuit 23 and the air introduction path 24 formed in the pressing members 16 and 17. It is configured as follows.
[0029]
The elongated tubular material Pb that has been stretch-formed in the previous step and is still heated (about 500 ° C.) is put into a mold M that is also heated to about 500 ° C. The mold M is clamped by the operation of the clamping cylinder, that is, the elevating cylinder 4. After fixing the both ends of the elongated tubular material Pb by the advancement of the left and right holders 6 and 7, if the pressing cylinders 12 and 13 are extended, the rod portions 12a and 13a push the tubular material Pa in the axial direction and push the shaft. While performing, if compressed air is pumped into the tubular material Pa through the compressed air supply path 23 and the air introduction path 24 from the compressed air source 22 and the internal pressure is applied to the expanded tubular material Pb, the expanded tubular material Pb is Then, hot pipe expansion molding (hot bulge molding) is performed so as to conform to the upper and lower molding surfaces 3 m and 2 m of the cavity 5.
[0030]
The expanded tubular material Pb after the pipe expansion molding is taken out from the mold M by opening the mold M after the left and right holders 6 and 7 are retracted, and the pipe expansion molding pipe (bulge molding pipe) shown in FIG. ) Pc is obtained. Thus, the tube-forming tube Pc has a large diameter portion of the hollow portion N, left and right side portions S, S that are tapered from left to right, and tapered left and right frustoconical portions. The left and right end portions E and E are cut to obtain a final molded product, that is, a hollow member P (see FIG. 1). ).
[0031]
By the way, as shown in FIG. 2 (b), the elongated tubular material Pb that has undergone the partial heating, total heating, internal pressurization, and tensioning steps (1) to (3) is cut off at the left and right end portions S and S. The face plate thickness is t, and the cross-sectional plate thickness of the intermediate portion N is 1.25 t larger than that, and the outer peripheral surface has no “necking” over the entire length, and is formed with a constant peripheral length. .
[0032]
In addition, as shown in FIG. 2 (c), the elongated tubular material Pb is formed such that its intermediate portion N is more radially positioned than the left and right end portions S and S, as shown in FIG. 2 (c). The expanded pipe Pc after the expanded molding can be made to have substantially the same thickness t over the entire length by being expanded and expanded to a large diameter, and as a result, the expanded pipe with the left and right end portions E and E cut off. Although the final molded product after molding, that is, the hollow member P has been changed in cross-sectional shape by pipe expansion molding, a pipe expansion molded pipe Pc having a substantially equal cross-sectional plate thickness t can be obtained over the entire length. And according to this 1st Example, the cross-sectional thinning of the bulge forming part which is a fault of the conventional pipe expansion forming (bulge forming) method is eliminated.
[0033]
Next, a second embodiment of the present invention will be described with reference to FIG.
[0034]
FIG. 6 is a diagram showing a manufacturing process for manufacturing a hollow member from a tubular material. As shown in FIG. 6A, the tubular material Pa has a thickness of 1. 5t.
[0035]
As shown in FIG. 6 (b), the tubular material Pa controls the partial heating temperature in the longitudinal direction by the partial energization heating process and the overall energization heating process as in the first embodiment, and the internal pressurization. In addition, by controlling the internal pressure and the tensile force by the tension forming process, there is no “necking” over the entire length, the circumference is constant, and the plate thickness of the intermediate portion N is 1.5 t. An elongated tubular material Pb having a plate thickness t can be obtained.
[0036]
As shown in FIG. 6 (c), the elongated tubular material Pb is subjected to the same (4) tube expansion molding (bulge molding) as in the first embodiment, so that the intermediate portion N is expanded into a large diameter, The expanded pipe Pc having a cross-sectional plate thickness of 1.25 t and thicker than the plate thickness t of the left and right side portions S, S can be obtained.
[0037]
And the pipe expansion forming pipe Pc after pipe expansion forming is the final molded product and obtains the hollow member P (refer FIG. 1) by cut | disconnecting the both ends E and E similarly to the said 1st Example.
[0038]
Next, a third embodiment of the present invention will be described with reference to FIG.
[0039]
FIG. 7 is a cross-sectional view of an internal pressurizing and tensile forming apparatus for a tubular material.
[0040]
In the third embodiment, (1) the partial heating process of the tubular material Pa, (2) the entire energization heating process of the tubular material Pa, and (4) the expansion (bulge) forming process of the elongated tubular material Pb in the first embodiment. However, (3) the specific structure of the internal pressurizing and tensile forming steps of the tubular material Pa is different from that of the first embodiment. That is, according to the third embodiment, as shown in FIG. 7, the tensile process in the axial direction by applying an internal pressure to the heated tubular material Pa is performed in the mold M1, and the tubular material Pa is formed by tension. Occasionally, the occurrence of partial “necking” on the outer peripheral surface can be more reliably prevented, and the peripheral length can be made constant over the entire length. The specific configuration will be described below with reference to FIG. The tubular material Pa that has been heated through the heating step with a temperature difference in the longitudinal direction (the left and right side portions S, S are at the recrystallization temperature (500 ° C. or higher), and the central portion N is at a lower temperature) , And set in a mold M1 for internal pressure and tension. The mold M1 includes a lower mold 55 fixed on a base 53 and an upper mold 54 that can be raised and lowered relative to the lower mold 55. The upper mold 54 is connected to a lift cylinder 56 and can be lifted and lowered. . In the mold M1, the tubular material Pa in a partially heated state is kept at an appropriate temperature so as to maintain the heated state. A sealing member 57 is provided at one opening end (left end portion in FIG. 6) of the tubular material Pa, and the other opening end (right end portion in FIG. 6) of the tubular material Pa is sealed there. The other sealing member 58 is provided, and the other sealing member 58 is connected to the tension cylinder 37 of the tension means PL. Further, an internal pressurizing means PR for pressurizing the inside of the tubular material Pa to a predetermined pressure is disposed at one end of the mold M1, and this internal pressurizing means PR is an internal pressurizing source. The pressurized air from 50 is configured to be pumped into the tubular material Pa through the pressurizing circuit 51.
[0041]
The tubular material Pa set in the mold M1 is operated by the operation of the tension cylinder 37 of the tension means PL while the internal pressure is maintained at a predetermined pressure by supplying pressurized air from the internal pressure means PR. The tubular material Pa is given a predetermined tension in its axial direction. As a result, the tubular material Pa elongates. At this time, the left and right side portions S, S heated to a high temperature as in the first embodiment extend quickly and increase in elongation, while the intermediate portion heated to a low temperature. N has a small elongation and can form elongated tubular materials Pb having different cross-sectional plate thicknesses in the axial direction.
[0042]
Thus, according to the third embodiment, when the tubular material Pa is stretch-formed, a predetermined internal pressure is applied to the tubular material Pa, and the outer shape thereof is regulated by the mold M1. The elongated tubular material Pb having a constant circumference over the entire length can be accurately formed without forming a “neck” in the tubular material Pa.
[0043]
The expanded tubular material Pb after the tensile molding can obtain a tube-expanded molded product having a variable cross-sectional shape perpendicular to the longitudinal direction through the tube expansion (bulge) molding process of the first embodiment.
[0044]
As is clear from the above examples, according to the method for manufacturing a hollow member according to the present invention, it is possible to manufacture a hollow member having a variable cross-sectional plate thickness in the longitudinal direction or having a different cross-sectional shape in the longitudinal direction. In particular, the tubular material can be easily and accurately produced by extending the axial direction by applying an internal pressure, without causing any partial “necking”, and with a substantially equal circumferential length over the entire length. be able to.
[0045]
As mentioned above, although the Example of this invention was described, this invention is not limited to the Example, A various Example is possible within the scope of the present invention.
[0046]
For example, in the above-described embodiment, the case where the forming method of the present invention is applied to a hollow member made of an aluminum alloy has been described. However, this can also be applied to the manufacture of other metal hollow members. The heating temperature of the tubular material and the mold is controlled according to the material of the tubular member. In this embodiment, air is used as the fluid that applies the internal pressure to the tubular material, but other fluids may be used.
[0047]
【The invention's effect】
As described above, according to the first aspect of the present invention, a hollow member having a variable cross-sectional thickness in the longitudinal direction can be manufactured. In particular, the tubular material is pulled in the axial direction by applying an internal pressure. Accordingly, a hollow member having substantially the same peripheral length over the entire length can be easily and accurately manufactured without causing partial “necking”.
[0048]
In addition, according to the invention described in claim 2, it is possible to manufacture hollow members having different cross-sectional shapes in the longitudinal direction, and in particular, by applying an internal pressure to the tubular material and pulling it in the axial direction, a partial “ It is possible to easily and accurately manufacture a hollow member having substantially the same peripheral length over the entire length without causing “necking”.
[Brief description of the drawings]
FIG. 1 is a perspective view of a hollow member manufactured by a manufacturing method of the present invention (first embodiment).
FIG. 2 shows a manufacturing process for manufacturing a hollow member from a tubular material (first embodiment).
FIG. 3 is a schematic process diagram of partial energization heating, overall energization heating, internal pressurization, and tension forming process, (first embodiment)
FIG. 4 is a cross-sectional view of an internal pressure and tension forming apparatus (first embodiment).
FIG. 5 is a sectional view of a bulge forming apparatus (first embodiment).
FIG. 6 shows a manufacturing process for manufacturing a hollow member from a tubular material (second embodiment).
FIG. 7 is a cross-sectional view of an internal pressure and tension forming apparatus (third embodiment).
[Explanation of symbols]
Pa ······· Tubular material Pb ·······································································

Claims (2)

The cross-sectional plate thickness orthogonal to the longitudinal direction is a method for producing a hollow member different in the longitudinal direction,
A heating step of heating the tubular material (Pa) with a temperature difference in its longitudinal direction;
A tensile step of applying an internal pressure to the tubular material (Pa) heated in the step and pulling the tubular material (Pa) in the axial direction;
A method for producing a hollow member, comprising: The cross-sectional shape orthogonal to the longitudinal direction is a method for producing a hollow member different in the longitudinal direction,
A heating step of heating the tubular material (Pa) with a temperature difference in its longitudinal direction;
A tensile step of applying an internal pressure to the tubular material (Pa) heated in the step and pulling the tubular material (Pa) in the axial direction;
The elongated tubular material (Pb) whose cross-sectional plate thickness in the direction orthogonal to the longitudinal direction is changed in the longitudinal direction in the step is set in the cavity (5) of the mold (M), and the elongated tubular material (Pb) Tube expansion molding process for expanding the tube by applying internal pressure to
A method for producing a hollow member, comprising:

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