JP2010051977A - Method of manufacturing hollow tube body - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a manufacturing method for forming a protruded part, a hole, a recess or the like in a hollow tube body with good accuracy by a small device. <P>SOLUTION: The method of manufacturing the hollow tube body 1 includes the steps of: arranging a divided mold 3 divided into plural parts in a circumferential direction and having a cavity 6a at a central part in an assembled state in the hollow part 2 of the hollow tube body 1 which is a tubular body having a hollow part 2; moving each mold segment 4 constituting the divided mold 3 in a direction vertical to the longitudinal direction of the hollow tube body 1 and directed from the inside of the hollow tube body 1 to the outside by inserting a wedge into the cavity 6a of the divided mold 3 in the axial direction of the hollow tube body 1; and expanding the hollow tube body 1 by pressing. At least one or more uneven parts having an uneven part at the outer surface of the divided mold 3 are disposed, and a shape corresponding to the shape of the uneven part is transferred to the hollow tube body 1 so as to carry out molding. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a method for manufacturing a hollow tube body, which is an improvement on a method of forming a convex portion, a hole, a dent, or the like in a hollow tube body that is a tubular body having a hollow portion such as a steering support beam. It is.

  In vehicles and various devices, hollow tubes excellent in strength are widely used as reinforcing members, etc., but this type of hollow tube plays various roles in cooperation with other members. In order to achieve this, it is often used by processing the convex part, the hole or the dent on itself. For example, a steering support beam, which is a hollow tube bridged between the left and right front pillars of a vehicle body inside an instrument panel at the front of an automobile, supports a clip or the like that holds a wire harness of an automobile device. For various reasons, it is necessary to process various shapes.

2. Description of the Related Art Conventionally, a method using hydraulic molding is known as a method for forming a convex portion, a hole, a dent, or the like in a hollow tube.
In this method, a machining liquid is injected into a hollow portion of a hollow tube body, and the pressure (internal pressure) applied to the machining liquid is combined with axial pushing forces from both ends of the hollow tube body so that various cross-sectional shapes are obtained. This is to process a hollow tube (Patent Documents 1 and 2).

  Further, as a method for forming a hole in a hollow tube, it is widely known to perform machining with a drill or the like.

A split mold is disposed in the hollow tube body, and the split mold is expanded in a direction perpendicular to the longitudinal direction of the hollow tube body from the inside to the outside to expand the hollow tube body. A method of joining a tubular body and a member is also widely known (Patent Document 3).
JP 2001-18016 A JP 2005-297060 A Japanese Patent Laid-Open No. 11-36859

By the way, in the method by the above hydraulic molding, it is necessary to arrange a mold along the cross-sectional shape to be molded for a part to be molded, and a constraining mold is arranged to restrain a member for a part that does not require molding. There is a need to. That is, in this method by hydraulic molding, it is necessary to manage the shape of the hollow tube body with a mold over the entire surface.
Moreover, in order to prevent deformation | transformation other than a process part, you have to process in the state which applied the pressure in the hollow tube body.
Therefore, in this method by hydroforming, an apparatus capable of managing the shape of the hollow tube body over the entire surface and capable of processing in a state where pressure is applied to the hollow tube body is required. It had to be a big one. In particular, in order to form a hollow tube having a length of more than 1 meter, such as a steering support beam of an automobile, the apparatus becomes very large, and there is a disadvantage that the cost increases.

  Further, in the method by machining using a drill or the like, since oil is used in the processing, there is a disadvantage that the oil must be washed.

  Moreover, since the prior art for expanding the hollow tube body is intended to join the hollow tube body and the member, it is configured on the assumption that the hollow tube body is processed over the entire circumference. The processing content was limited.

  Under such a background, using a device smaller than the method by hydraulic molding, it is possible to accurately process the hollow tube body, and the step of washing the oil can be omitted. There has been a demand for a manufacturing method capable of processing only a part of the entire circumference of the hollow tube body. However, since it is difficult to reduce the size of the apparatus, no effective and appropriate device is provided.

  The present invention has been made in consideration of such circumstances, and the purpose thereof is to accurately process a hollow tube body such as a convex portion, a hole, and a depression with a small device, and It is an object of the present invention to provide a production method that can omit the step of washing oil and can process only a part of the entire circumference of the hollow tube body.

In order to achieve the above object, the present invention provides the following means.
According to the method for manufacturing a hollow tube of the present invention, a hollow portion of a hollow tube having a hollow portion is divided into a plurality of portions in the circumferential direction, and a hollow portion is formed at the center in an assembled state. The split molds are arranged, wedges are inserted into the hollow parts of the split molds in the axial direction of the hollow tubes, and the mold segments constituting the split molds are arranged in the longitudinal direction of the hollow tubes. In the method for manufacturing a hollow tube, the outer surface of the split mold is moved in a direction perpendicular to the direction from the inside to the outside of the hollow tube, and the hollow tube is expanded and expanded. It is characterized in that at least one concavo-convex portion having a concavo-convex shape is provided, and a shape corresponding to the shape of the concavo-convex portion is transferred to the hollow tube and molded.

  Further, in the method for producing a hollow tube of the present invention, a concave-convex mold having a shape that fits the concave-convex portion at a position corresponding to a position where the concave-convex portion presses on the outer surface of the hollow tube body. Is preferably arranged.

  Further, in the method for manufacturing a hollow tube according to the present invention, the concavo-convex portion has a shape that is perpendicular to the longitudinal direction of the split mold and bulges outward in a state where the split mold is combined. It is a bulging portion, and it is preferable to form a convex portion having a shape corresponding to the shape of the bulging portion in the hollow tube body.

  Further, in the method for manufacturing a hollow tube according to the present invention, the protrusions and protrusions are shaped so as to protrude outwardly in a state perpendicular to the longitudinal direction of the split mold in the state where the split mold is combined. It is preferable that a hole is formed in the hollow tube body.

  Further, in the method for manufacturing a hollow tube according to the present invention, the concavo-convex portion is a dent portion having a dent shape, and the bulging mold swelled into a shape that fits into the dent portion includes By pressing toward the hollow portion from the position corresponding to the position where the hollow portion is pressed against the outside of the hollow tube body, the hollow tube body is perpendicular to the longitudinal direction of the hollow tubular body from the outside. It is preferable to form a recess that is recessed inward.

  Further, in the method for manufacturing a hollow tube of the present invention, the concavo-convex portion is a concave portion, and a protruding mold protruding into a shape that fits into the concave portion is provided outside the hollow tube body, and the concave portion is It is preferable to form a hole in the hollow tube body by piercing from the position corresponding to the pressing position toward the concave portion.

  Moreover, in the manufacturing method of the hollow tube body of this invention, it is preferable that the cross-sectional shape of the said hollow tube body is a polygonal shape.

  Further, in the method for manufacturing a hollow tube according to the present invention, the uneven portion having a more uneven shape may be provided in a portion where the hollow tube of the split mold is expanded over the entire circumference. preferable.

  Further, in the method for producing a hollow tube according to the present invention, in the step of inserting the hollow tube into an insertion hole provided in a member and expanding and expanding the hollow tube, It is preferable that the hollow tube body and the member are joined by expanding the insertion portion of the hollow tube body into the insertion hole and the vicinity of both sides in the axial direction of the hollow tube body of the insertion portion.

  In the hollow tube manufacturing method of the present invention, the hollow tube is, for example, a steering support beam body of a vehicle.

In the present invention, as a result of adopting the above-described configuration, an effect is obtained that it is possible to accurately process the concave and convex portions such as convex portions, holes, and dents on the hollow tube body without requiring a large-scale device.
Moreover, since oil is not used at the time of a process, the effect that the process which wash | cleans oil can be skipped is also acquired.
Furthermore, by adjusting the position and shape of the concavo-convex portion provided in the split mold, it is possible to obtain an effect that only a part of the entire circumference of the hollow tube body can be processed.

  In addition, it is possible to accurately process the unevenness by arranging an uneven mold having a shape that fits with the uneven portion at a position corresponding to the position where the uneven portion is pressed on the outer surface of the hollow tube body. An effect is also obtained.

  Moreover, the effect that a hollow tube body can be processed efficiently is also acquired by joining a hollow tube body and a member simultaneously.

  Hereinafter, the manufacturing method of the hollow tube which is embodiment of this invention is demonstrated with reference to drawings.

[First Embodiment]
FIG. 1 is a perspective view in which a part of a hollow tube and a split mold used in the first embodiment of the present invention is omitted, and FIG. 2 shows a state in which the split mold is arranged in a hollow pipe. It is the perspective view which abbreviate | omitted some shown. FIG. 3 is a cross-sectional view in which a part of the hollow tube body is omitted. FIG. 3A shows a state where the split mold is disposed in the hollow tube body, and FIG. The state when the split mold extrudes the hollow tube is shown.

  As shown in FIG. 1, the hollow tube body 1 of the present embodiment is a tubular body having a hollow portion 2, and the cross section is formed in a substantially circular shape as shown in FIGS. 3 (a) and 3 (b). Yes. In addition, the split mold 3 of the present embodiment has a configuration in which a tubular mold having a hollow portion 6 a at the center is divided in the circumferential direction, and includes eight mold segments 4. As shown in FIG. 3 (a), the cross section of the divided mold 3 is also formed in a substantially circular shape when the divided end surfaces of the respective mold segments 4, 4,. .

  The center inner surfaces 6, 6,... Of the mold segments 4, 4,... Are formed so that a circular cavity 6a is defined therein. The diameter of the hollow portion 6a is gradually reduced toward the (A direction).

  In FIG. 3 (b), M is a mandrel (wedge), which is inserted into the cavity 6a of the divided mold 3 and is in contact with the center inner surfaces 6, 6,. The mold segments 4, 4,... Are expanded by inserting them further deeply.

  On the outer surface of the mold segment 4 constituting the split mold 3, a bulging portion 5 (uneven portion) bulging outward in the radial direction is provided. As shown in FIG. 1, the bulging portion 5 is not provided over the entire circumference of the split mold 3 but is provided only for a part thereof.

  Hereinafter, the manufacturing method which processes an unevenness | corrugation to the hollow tube body 1 using the division mold 3 is demonstrated.

First, as shown in FIGS. 2 and 3A, the split mold 3 is disposed in the hollow tube 1.
Next, an unillustrated mandrel (wedge) is inserted into the cavity 6 a of the split mold 3. Accordingly, the eight mold segments 4 constituting the split mold 3 are respectively outward in the radial direction of the hollow tube 1 (perpendicular to the longitudinal direction of the hollow tube 1 and from the inside of the hollow tube 1). (The direction toward the outside), the hollow tubular body 1 is expanded and expanded.

  As shown in FIG. 3B, the bulging portion 5 formed on the mold segment 4 constituting the split mold 3 is pressed against the hollow tubular body 1 from the inside by the above-described process, and the bulging portion 5 The shape is transferred to the hollow tubular body 1, and the convex portion 7 is formed.

Since the manufacturing method of the hollow tube 1 according to the present embodiment adopts the above-described configuration, the shape provided in the split mold 3 is transferred to form irregularities in the hollow tube 1. Can be processed with high accuracy in the hollow tube 1.
Moreover, since oil is not used at the time of a process, the effect that the process which wash | cleans oil can be skipped is also acquired.
Furthermore, the effect that it can process only about a part of the perimeter of a hollow tube body is also acquired.

In the present embodiment, the divided mold 3 is configured to include the eight mold segments 4. However, the number of the divided molds 3 is not limited to eight as long as it is plural, and may be an even number or an odd number.
Moreover, although the number of the bulging parts 5 provided in the mold segment 4 constituting the split mold 3 is one, a plurality of the bulging parts 5 may be provided, or the plurality of mold segments 4 may be provided separately. .

In the present embodiment, the hollow tube 1 having a substantially circular cross section is used. However, as shown in FIG. 4, the hollow tube 1 may have a polygonal cross section. In that case, it is preferable that the divided mold 3 also has a shape that matches the shape of the hollow tube 1.
4A shows a state in which the split mold 3 is disposed in the hollow tube 1, and FIG. 4B shows a state in which the split mold 3 extrudes the hollow tube 1. The state of is shown.

[Second Embodiment]
FIG. 5 is a cross-sectional view in which a part of the hollow tube used in the method for manufacturing a hollow tube according to the second embodiment of the present invention is omitted, and FIG. FIG. 5 (b) shows a state when the split mold is disposed in FIG. 5B, and a state when the split mold extrudes the hollow tube body. FIG. 6 is a cross-sectional view in the vicinity of a portion where the hollow tube body and the split mold are in contact with each other, and FIG. 6A is a diagram illustrating a state when the split mold is disposed in the hollow tube body. 6 (b) shows a state when the split mold extrudes the hollow tube.
In addition, this embodiment is a modification of 1st Embodiment, and abbreviate | omits description about the same part.

As shown in FIGS. 5A and 5B and FIGS. 6A and 6B, in the present embodiment, protruding protrusions 8 (unevenness) are formed on the outer surface of the mold segment 4 constituting the divided mold 3. Part). The tip of the protrusion 8 is a sharp point 8a.
A concave mold 10 (concave / convex mold) having a concave portion 9 shaped to fit with the protruding portion 8 is disposed on the outer surface of the hollow tube 1 at a position corresponding to the position where the protruding portion 8 is pressed. Has been.

  Then, when the hollow tube 1 is expanded, the protrusion 8 is pierced toward the recess 9 of the recess mold 10, thereby forming the hole 11.

Also in the manufacturing method of the present embodiment, the same effect as that of the first embodiment can be obtained, and the hole 11 can be accurately formed in the hollow tube 1.
In addition, since the concave mold 10 is arranged, when the hole 11 is opened, it is possible to prevent the vicinity of the hole 11 of the hollow tubular body 1 from rising, and the effect that the hole 11 can be accurately opened is obtained. It is done.

In the present embodiment, the hollow tube 1 having a substantially circular cross section is used. However, as shown in FIG. 7, the hollow tube 1 may have a polygonal cross section. In that case, it is preferable that the divided mold 3 also has a shape that matches the shape of the hollow tube 1.
7A shows the state when the split mold 3 is disposed in the hollow tube 1, and FIG. 7B shows the state when the split mold 3 extrudes the hollow tube 1. The state of is shown.

[Third Embodiment]
FIG. 8 is a cross-sectional view of the vicinity of a portion where the hollow tube used in the method for manufacturing a hollow tube according to the third embodiment of the present invention and the bulging mold are in contact with each other, and FIG. FIG. 8B shows a state immediately before the bulging mold is pressed into the hollow tube body, and FIG. 8B shows a state when the bulging mold is pressed into the hollow tube body.
In addition, this embodiment is a modification of 1st Embodiment, and abbreviate | omits description about the same part.

As shown in FIGS. 8A and 8B, in this embodiment, the divided mold 3 is provided with a recessed portion 21 (uneven portion) having a recessed shape.
Further, the bulging mold 23 having the bulging portion 22 bulging into a shape that fits into the hollow portion 21 is disposed outside the hollow tube body 1 at a position corresponding to the position where the hollow portion 21 is pressed. Yes.

  Then, the bulging mold 23 is pressed against the hollow portion 21 of the split mold 3 from a position corresponding to the position where the hollow portion 21 of the split mold 3 is pressed on the outside of the hollow tube 1. A hollow 24 that is recessed inward in the radial direction of the hollow tube 1 is formed in the tube 1.

  Even in the manufacturing method of the present embodiment, the same effect as that of the first embodiment can be obtained, and the hollow 24 can be provided in the hollow tube 1 with high accuracy.

[Fourth Embodiment]
FIG. 9 is a cross-sectional view of the vicinity of a portion where the hollow mold body and the protruding mold are in contact with each other used in the method for producing a hollow pipe body according to the fourth embodiment of the present invention, and FIG. FIG. 9B shows a state immediately before the protruding mold is pierced into the hollow tube body, and FIG. 9B shows a state when the protruding mold is pierced into the hollow tube body.
Note that this embodiment is a modification of the third embodiment, and description of similar parts is omitted.

As shown in FIGS. 9A and 9B, in the present embodiment, the split mold 3 is provided with a recess 25 (uneven portion).
In addition, a protruding mold 27 having a protruding portion 26 protruding into a shape that fits into the recessed portion 25 is disposed outside the hollow tube 1 at a position corresponding to a position where the recessed portion 25 is pressed. The tip of the protrusion 26 is a sharp point 26a.

  Then, the protruding mold 27 is pierced from the position corresponding to the position where the concave portion 25 of the split mold 3 is pressed against the outer side of the hollow tube body 1 toward the concave portion 25 of the split mold 3, so Hole 28 is formed.

  Also in the manufacturing method of the present embodiment, the same effect as that of the first embodiment can be obtained, and the hole 28 can be formed in the hollow tube 1 with high accuracy.

[Fifth Embodiment]
FIG. 10 is a cross-sectional view of the vicinity of a portion where a hollow mold body and a split mold are in contact with each other used in the method for producing a hollow pipe body according to the fifth embodiment of the present invention. FIG. 10B shows a state when the split mold is disposed in the hollow tube, and FIG. 10B shows a state when the split die is extruded through the hollow tube.
In addition, this embodiment is a modification of 1st Embodiment, and abbreviate | omits description about the same part.

As shown in FIGS. 10 (a) and 10 (b), the split mold 3 of this embodiment has a shape that further bulges outward in a portion 41 that expands the hollow tube 1 and expands the tube around the entire circumference. The bulging portion 42 (uneven portion) is provided.
Then, when the hollow tube 1 is expanded and expanded by the split mold 3, the bulging portion 42 of the split mold 3 is further outwardly directed to the portion 43 expanded over the entire circumference of the hollow tube 1. The shape corresponding to the shape is transferred to form the convex portion 44.

  Also in the manufacturing method of the present embodiment, the same effect as that of the first embodiment can be obtained, and the convex portion 44 can be further provided outward in the portion 43 expanded over the entire circumference of the hollow tube 1. .

[Sixth Embodiment]
FIG. 11: is sectional drawing of the site | part vicinity of the hollow tube used for the manufacturing method of the hollow tube which is the 6th Embodiment of this invention, and a division | segmentation metal mold | die, FIG. FIG. 11B shows a state when the split mold is disposed in the hollow tube, and FIG. 11B shows a state when the split mold extrudes the hollow tube. FIG. 12 shows a state of the hollow tube body after processing according to the present embodiment.

The hollow tubular body 1 to be processed in the present embodiment is a vehicle steering support beam main body 47 shown in FIG. 12, and brackets 45 as various members are joined.
All the brackets 45 are configured to have an insertion hole 46, and the steering support beam main body 47 is inserted into the insertion hole 46.

  Further, as shown in FIG. 11 (a), the split mold 3 is slightly bulged outward over the entire circumference at a portion 48 that presses against the insertion portion 52 of the steering support beam main body 47 inserted through the bracket 45. In the region 49 near the both sides in the axial direction of the portion 48 that presses against the insertion portion 52, it is larger than that and bulges outward over the entire circumference.

  Moreover, as shown to Fig.11 (a), the division | segmentation metal mold | die 3 is provided with the bulging part 50 (uneven part) of the bulging shape.

  The manufacturing method of the steering support beam main body 47 will be described. First, as shown in FIG. 11A, the split mold 3 having the above-described shape is arranged in the steering support beam main body 47. Next, as shown in FIG. 11 (b), a mandrel (not shown) is inserted in the hollow portion 6 a of the split mold 3 shown in FIG. 1 in the axial direction of the steering support beam main body 47, and the split mold 3 Is moved outward in the radial direction of the steering support beam main body 47, and the steering support beam main body 47 is expanded and expanded.

By processing in this way, the bulging portion 50 of the split mold 3 is pressed against the steering support beam main body 47 from the inside, and the shape of the bulging portion 50 is transferred to the steering support beam main body 47, and the convex portion 51 is formed.
Further, the insertion portion 52 of the steering support beam main body 47 is expanded over the entire circumference by the split mold 3, so that the steering support beam main body 47 is pressed against the peripheral edge portion of the insertion hole 46 of the bracket 45. In addition, the bracket 45 is deformed so that the insertion hole 46 extends outward, and the restoring force of the bracket 45 is combined to join the steering support beam main body 47 and the bracket 45 together.
Further, since the pipes are expanded by the split mold 3, the vicinity of both sides in the axial direction of the insertion part 52 of the steering support beam main body 47 forms a bulging portion 53 having a shape bulging over the entire circumference. The movement of the steering support beam body 47 in the axial direction is restricted.

  As a result of adopting the above configuration, the method for manufacturing the hollow tube body 1 of the present embodiment can obtain the same effects as those of the first embodiment. In addition, it is possible to obtain an effect that the convex portion 51 can be provided on the steering support beam main body 47 that is the hollow tube body 1 and the bracket 45 that is a member can be joined by one expansion.

  In the present embodiment, one bulging portion 50 is provided in the divided mold 3, but a plurality of bulging portions 50 may be provided, and as shown in FIG. 13, the second to fifth embodiments may be used. The holes 54 and the depressions 55 may be formed at the same time by combining the manufacturing methods shown in the form.

  The present invention can be widely used in the manufacturing industry for processing hollow tubes.

FIG. 1 is a perspective view in which a hollow tube body and a part of a split mold according to the first embodiment of the present invention are omitted. FIG. 2 is a perspective view in which a part of the split mold according to the first embodiment of the present invention is shown in a hollow tube with a part thereof omitted. FIG. 3 is a cross-sectional view in which a part of the hollow tube body according to the first embodiment of the present invention is omitted, and FIG. 3A is a view when a split mold is arranged in the hollow tube body. FIG. 3B shows a state when the split mold extrudes the hollow tube body. FIG. 4 is a cross-sectional view in which a part of the hollow tube body according to the first embodiment of the present invention is omitted, and FIG. 4A is a view when a split mold is arranged in the hollow tube body. FIG. 4B shows a state when the split mold extrudes the hollow tube body. FIG. 5 is a cross-sectional view in which a part of the hollow tube body according to the second embodiment of the present invention is omitted, and FIG. 5A is a view when a split mold is arranged in the hollow tube body. FIG. 5B shows a state when the split mold extrudes the hollow tube body. FIG. 6 is a cross-sectional view of the vicinity of a portion where the hollow tube body and the split mold according to the second embodiment of the present invention are in contact with each other, and FIG. 6A shows the split mold disposed in the hollow tube body. FIG. 6B shows a state when the split mold is extruded through the hollow tube. FIG. 7 is a cross-sectional view in which a part of the hollow tube body according to the second embodiment of the present invention is omitted, and FIG. 7A is a view when a split mold is arranged in the hollow tube body. FIG. 7B shows a state when the split mold extrudes the hollow tube body. FIG. 8 is a cross-sectional view of the vicinity of a portion where the hollow mold body and the split mold according to the third embodiment of the present invention are in contact with each other. FIG. FIG. 8B shows a state immediately before being pressed, when the bulging mold is pressed against the hollow tube body. FIG. 9 is a cross-sectional view of the vicinity of a portion where the hollow mold body and the split mold according to the fourth embodiment of the present invention are in contact with each other, and FIG. 9A is a diagram illustrating a projecting mold sticking into the hollow pipe body. FIG. 9B shows the state immediately before, when the protruding mold is stuck into the hollow tube body. FIG. 10 is a cross-sectional view of the vicinity of the portion where the hollow tube body and the split mold according to the fifth embodiment of the present invention are in contact with each other, and FIG. 10A shows the split mold placed in the hollow tube body. FIG. 10B shows a state when the split mold is extruded through the hollow tube. FIG. 11 is a cross-sectional view of the vicinity of a portion where the hollow tube body and the split mold according to the sixth embodiment of the present invention are in contact with each other, and FIG. 11A shows the split mold disposed in the hollow tube body. FIG. 11 (b) shows a state when the split mold is extruded through the hollow tube. FIG. 12 is a perspective view showing a state of the hollow tube body after processing according to the sixth embodiment of the present invention. FIG. 13: is a perspective view which shows the mode of the hollow tube body after a process of the 6th Embodiment of this invention.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Hollow tube body, 2 ... Hollow part, 3 ... Split mold, 4 ... Mold segment, 5 ... Swelling part, 6 ... Center part inner surface, 6a ...・ Cavity, 7 ... convex, 8 ... projection, 9 ... concave, 10 ... concave mold, 11 ... hole, 21 ... concave, 23 ... Inflated mold, 24 ... depression, 25 ... recessed part, 27 ... projecting mold, 28 ... hole, 41 ... expanded tube portion, 46 ... insertion hole, 47 ... steering Support beam body, 52 ... insertion part

Claims (10)

In the hollow portion of the hollow tube body that is a tubular body having a hollow portion, a split mold in which a hollow portion is formed at the center portion in a state of being divided into a plurality in the circumferential direction and being assembled,
A wedge is inserted into the hollow portion of the split mold in the axial direction of the hollow tube body, and each mold segment constituting the split mold is perpendicular to the longitudinal direction of the hollow tube body. In the method for manufacturing a hollow tube having a step of expanding the tube by expanding the hollow tube by moving it from the inside to the outside of the body,
Providing at least one uneven portion on the outer surface of the split mold,
A method for producing a hollow tube, wherein a shape corresponding to the shape of the uneven portion is transferred to the hollow tube and molded.   The inside of the hollow tube body outer surface, the uneven | corrugated metal mold | die which has a shape fitted with the said uneven part is arrange | positioned in the position corresponding to the position where the said uneven part presses. A method for producing an empty tube.   The concavo-convex portion is a bulging portion having a shape bulging outward and perpendicular to the longitudinal direction of the divided mold in a state where the divided dies are combined. The method for producing a hollow tube according to claim 1 or 2, wherein a convex portion having a shape corresponding to the shape of the portion is formed.   In the state where the divided molds are combined, the uneven part is a protruding part that has a shape protruding outward and perpendicular to the longitudinal direction of the divided mold, and forming a hole in the hollow tube body The manufacturing method of the hollow tube body of Claim 1 or Claim 2 characterized by these. The uneven portion is a recessed portion having a recessed shape,
By pressing the bulging mold swelled into a shape that fits into the dent, from the position corresponding to the position where the dent is pressed against the outside of the hollow tube body, the dies are pressed toward the dent. The hollow tube body manufacturing method according to claim 1, wherein the hollow tube body is formed with a recess that is perpendicular to the longitudinal direction of the hollow tube body and that is recessed from the outside toward the inside. The uneven portion is a recess,
By projecting a projecting mold projecting into a shape that fits into the recess into the hollow tube body from the position corresponding to the position at which the recess is pressed on the outside of the hollow tube body, The method for manufacturing a hollow tube according to claim 1, wherein a hole is formed.   The method for manufacturing a hollow tube according to any one of claims 1 to 6, wherein a cross-sectional shape of the hollow tube is a polygonal shape.   8. The uneven portion having a further uneven shape is provided at a portion where the hollow tube body of the split mold is expanded over the entire circumference. 9. The manufacturing method of the hollow pipe body as described in any one of. The hollow tube is inserted into an insertion hole provided in the member,
In the step of expanding and expanding the hollow tube body, the insertion portion of the hollow tube body into the insertion hole and the vicinity of both sides in the axial direction of the hollow tube body are expanded, and the hollow tube body is expanded. The method for manufacturing a hollow tube according to any one of claims 1 to 8, wherein the tube and the member are joined.   The method for manufacturing a hollow tube according to any one of claims 1 to 9, wherein the hollow tube is a steering support beam body of a vehicle.

Images