JP2009131880A - Method of manufacturing eccentrically expanded pipe and concentric die - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method of manufacturing an eccentrically expanded pipe, in which reduction in thickness of the peripheral surface of a highly expanded pipe on which cracking and necking are apt to occur is suppressed. <P>SOLUTION: In the state where the end part 11 of a pipe stock part 1 is projected in the range of the concentric inner surface 311 of a concentric die 31 having a concentric inner surface 311 having a radius De which is larger than the orthogonal distance Ds from the axial center Oo of the pipe stock part 1 to the peripheral surface 21 of a low expansion pipe of an expanded part 2 and the concentric inner surface 311 having a radius De which is smaller than the orthogonal distance Db from the axial center Oo of the pipe stock part 1 to the peripheral surface 22 of the highly expanded pipe 22 of the expanded part 2, by force-fitting the concentric punch 32 into the end part 11 of the pipe stock part 1, the end part 11 is expanded concentrically. In the state where the end part 11 of the pipe stock part 1 which is concentrically expanded is projected in the range of the eccentric inner surface 411 of the eccentric die 41 having the eccentric inner surface 411 equal to the outer shape of the expanded part 2 and the end part 11 is inclined toward the peripheral surface 22 of the highly expanded pipe of the end part 11 by applying the peripheral surface 21 of the lowly expanded pipe of the end part 11 to the eccentric inner surface 411, the eccentric punch 42 is force-fitted into the end part 11 and the end part 11 is eccentrically expanded. <P>COPYRIGHT: (C)2009,JPO&amp;INPIT

Description

  The present invention relates to a method for manufacturing an eccentric expansion pipe that connects, for example, a fuel supply pipe body of a fuel supply pipe and a filler neck, and a concentric die.

  First, identify the terms used below. The concentric tube expansion means a tube body having a tube expansion portion in which the axial core of the tube expansion portion is concentric with respect to the shaft core of the raw tube portion, and is produced by a concentric tube expansion step. The concentric tube expansion step is a step of performing tube expansion processing (concentric tube expansion processing) while keeping the end portion of the raw tube portion concentric with the axial core of the raw tube portion. Use a punch. The concentric die has a concentric inner surface that follows the end of the raw tube portion after the concentric tube expansion step, that is, the tube expansion portion. The concentric punch is press-fitted into the end portion in a state where the end portion of the raw tube portion projects within the range of the concentric inner surface.

  The eccentric tube expansion means a tube body having a tube expansion portion in which the shaft core of the tube expansion portion is eccentric with respect to the axis core of the raw tube portion, and is made by an eccentric tube expansion process. The eccentric tube expansion step is a step of performing tube expansion processing (eccentric tube expansion processing) by decentering the end portion of the tube portion or the end portion of the tube portion that has been previously concentric tube expanded from the axis of the tube portion. Yes, a pair of specific eccentric die and eccentric punch are used. The eccentric die has an eccentric inner surface that follows the end of the raw tube portion after the eccentric tube expanding step, that is, the tube expanding portion. The eccentric punch is press-fitted in a state in which the end of the element pipe part or the end of the element pipe part that has been concentrically expanded in advance protrudes within the range of the inner surface of the concentric core.

  The expanded tube portion subjected to the eccentric tube expansion process is eccentric with respect to the raw tube portion. Therefore, the side where the peripheral surface of the pipe expansion part is greatly separated in the radial direction from the peripheral surface of the raw pipe part is referred to as a high expansion side, and the peripheral surface on the high expansion side is referred to as a high expansion peripheral surface. Similarly, the side where the peripheral surface of the pipe expansion part is not far away from the peripheral surface of the raw pipe part in the radial direction or the side which is not separated at all is referred to as a low pipe expansion side, and the peripheral surface on the low pipe expansion side is referred to as a low pipe expansion peripheral surface. From this point, the end of the raw pipe part at the stage where the concentric pipe expansion process is finished has the same outer diameter of the high pipe expansion peripheral surface and the low pipe expansion peripheral surface, but the pipe expansion part after the eccentric pipe expansion process is high The outer diameter of the expanded pipe peripheral surface is larger than the outer diameter of the low expanded peripheral surface.

  As the fuel supply pipe, an eccentric expansion pipe is used in which the axis of the pipe expansion section is eccentric with respect to the axis of the base pipe section. Specifically, the fuel pipe main body in which the raw pipe portion is connected to the fuel tank, and the expanded portion become the filler neck. For example, an eccentric expansion tube with a small expansion rate (expansion rate = outer diameter of the expanded portion / outer diameter of the raw tube portion x 100 = around 120%) is an eccentric die having an eccentric inner surface equal to the outer shape of the expanded portion. It can be manufactured only by an eccentric tube expansion process in which an eccentric punch is press-fitted and the end portion is subjected to an eccentric tube expansion process in a state where the end portion of the raw tube portion is projected in the range of the eccentric inner surface. Here, in recent fuel supply pipes, the standardized filler neck cannot be reduced and the expansion ratio of the eccentric pipe expansion is increased with respect to the fuel pipe main body that is thinned for improving the fuel supply and reducing the weight. . And if the pipe expansion rate is large, cracks and necking will occur in the pipe expansion part. Therefore, eccentric pipe expansion with a large pipe expansion ratio (around 150% pipe expansion ratio) may be performed by combining the concentric pipe expansion process and the eccentric pipe expansion process. It is manufactured by repeating the core expansion process or the eccentric expansion process.

  Patent Document 1 discloses a concentric tube expansion process (coaxial tube expansion process) in which an end portion (expanded tube portion) of an element tube portion is processed by concentric tube expansion, and an end portion of the element tube portion is moved in an axis orthogonal direction (radial direction). And a method of manufacturing an eccentric tube expansion, which is combined with an eccentric tube expansion step of further expanding the end portion of the tube (claim 1 and others). The manufacturing method disclosed in Patent Document 1 is characterized in that one or a plurality of concentric tube expansion steps and a single eccentric tube expansion step are combined. As a result, an eccentric tube expansion process that may cause cracks and necking in the expanded portion is performed only once, and a large tube expansion rate is achieved while suppressing the generation of the cracks and necking (to solve the problem). And the effects of the invention).

  Patent Document 2 discloses an end portion (coaxially) of a coaxially expanded pipe portion in which the length in the axial direction (length in the tube axis direction) of the highly expanded peripheral surface (eccentric side) is made longer than the low expanded surface (non-eccentric side). A concentric tube expansion step (coaxial diameter expansion step) for forming a diameter expansion pipe end) and an eccentric punch (punch cylindrical portion) that contacts the high expansion peripheral surface before the low expansion peripheral surface are press-fitted into the end portion. An eccentric tube expansion manufacturing method combining an eccentric tube expansion step (eccentric diameter expansion step) for forming an eccentric tube expansion portion (eccentric diameter expansion tube end) is disclosed. In the manufacturing method disclosed in Patent Document 2, the material flow on the high-expansion peripheral surface is suppressed in the eccentric pipe expansion step, and the material flow from the low-expansion peripheral surface to the high-expansion peripheral surface is promoted. It is said that typical thinning is suppressed (effect of the invention).

  In Patent Document 3, when a plurality of eccentric punches (expansion punches) having different maximum diameters but the same taper angle are press-fitted into an end portion (press-fit portion) of the raw pipe portion in order from the one having the smallest maximum diameter, Each eccentric punch discloses a method of manufacturing an eccentric expansion pipe that is press-fitted while applying an axial compressive force so as to press the end of the raw tube portion against the eccentric inner surface (clamp-type inner surface) of the eccentric die. . In the manufacturing method disclosed in Patent Document 3, a plurality of eccentric punches are press-fitted in stages so that the plate thickness of the expanded tube portion can be maintained at 70% or more of the plate thickness of the raw tube portion, and breakage occurs during molding. It is said that an eccentric tube expansion (high tube expansion) with a large tube expansion rate, which is advantageous in terms of strength, can be obtained (effect of the invention).

Japanese Patent No. 3342006 JP 2002-102959 A Japanese Patent No. 3549750

  The eccentric tube expansion process is mainly performed by press-fitting an eccentric punch into the end portion of the core tube portion that protrudes into the range of the eccentric inner surface of the eccentric die or the end portion that has already been subjected to the concentric tube expansion process. The peripheral surface is pulled and plastically deformed to form the expanded portion. For this reason, the thickness of the highly expanded peripheral surface is reduced. This is a cause of causing cracks and necking on the highly expanded peripheral surface of the expanded portion. From this, in order to prevent the occurrence of cracking and necking of the expanded portion, it is conceivable to first avoid the tension biased toward the highly expanded peripheral surface. In Patent Document 1, the eccentric tube expansion process is performed only once, and the tension biased toward the highly expanded peripheral surface is avoided. However, even if it is only once, there is no change in pulling toward the highly expanded peripheral surface, and it is expected that cracks and necking will occur on the highly expanded peripheral surface of the expanded portion as the expansion rate increases.

  The manufacturing method disclosed in Patent Document 2 employs an eccentric tube expansion process that compensates for the plate thickness of the highly expanded peripheral surface that is thinned by being biased toward the highly expanded peripheral surface. Specifically, the material flow on the high expansion peripheral surface is suppressed and the material flow from the low expansion peripheral surface to the high expansion peripheral surface is promoted, so that local thinning in the circumferential direction is suppressed. However, it is unclear what kind of phenomenon “material flow” specifically means, and it is not known how to suppress the decrease in the thickness of the highly expanded peripheral surface. It is unclear how much necking is suppressed.

  On the other hand, the manufacturing method disclosed in Patent Document 3 avoids unreasonable pipe expansion by performing stepwise pipe expansion, and the portion that becomes the pipe expansion section (end portion of the raw pipe section) in the axial direction at each pipe expansion. By compressing, it is suppressed that the plate | board thickness of a highly expanded peripheral surface becomes thin, and generation | occurrence | production of a crack and necking can be prevented. However, since the end portion of the raw pipe portion is expanded step by step, the eccentric tube expansion step is required a plurality of times, and there is a problem that the production efficiency of the eccentric tube expansion is lowered. In addition, a plurality of types of eccentric punches are required, but each eccentric punch employs a separate structure that achieves both expansion and compression, and therefore, it takes time and effort to design and manufacture the eccentric punch. As a result, there is a risk of increasing the cost of the eccentric tube expansion.

  From the above, although the manufacturing method disclosed in Patent Document 3 is considered to be relatively preferable, there are problems of production efficiency and cost increase, which are practically difficult to adopt. Therefore, with the goal of reducing the thickness of the highly expanded peripheral surface where cracking and necking are likely to occur, the eccentric tube expansion process is reduced as much as possible without reducing the production efficiency and the eccentric punch. In order to develop a manufacturing method for eccentric tube expansion that does not increase the cost of eccentric tube expansion, we studied.

  As a result of the examination, an eccentric tube expansion manufacturing method in which the end portion of the element pipe portion is plastically deformed by the concentric tube expansion step and the eccentric tube expansion step, and the concentric tube expansion step The concentric die having a concentric inner surface having a radius larger than the orthogonal distance from the axial center of the expanded tube portion to the low expanded peripheral surface of the expanded tube portion and smaller than the orthogonal distance from the axial core of the element tube portion to the higher expanded peripheral surface of the expanded tube portion. In a state where the end of the core pipe part protrudes in the range of the concentric inner surface, a concentric punch is press-fitted into the end part of the base pipe part, the end part is subjected to concentric pipe expansion processing, The end of the core pipe portion that has been subjected to concentric pipe expansion is projected into the range of the eccentric inner surface of the eccentric die having an eccentric inner surface equal to the outer shape of the pipe expansion portion, and the low pipe expansion peripheral surface of the end portion is the eccentric inner surface. The eccentric punch is press-fitted into the end portion while the end portion is inclined toward the highly expanded peripheral surface of the end portion, and the end portion is eccentrically expanded. Method of manufacturing a pipe expansion was developed.

  The present invention is similar to the conventional manufacturing method in that the concentric tube expanding step and the eccentric tube expanding step are combined, but the functions of the respective steps are different. In the eccentric tube expansion process, when the eccentric tube expansion process is performed by pulling the end of the core tube portion that has been concentric tube expanded by press-fitting an eccentric punch, the low tube expansion peripheral surface of the end portion is used as the eccentric inner surface of the eccentric die. The end is inclined toward the high expansion side. The bending of the end portion of the raw tube portion is a force that bends the highly expanded peripheral surface of the end portion by elastic deformation, that is, generates a compressive force in the axial direction on the highly expanded peripheral surface, and is applied during eccentric tube expansion processing. The pulling force in the core direction is reduced by the compression force. Thereby, since the highly expanded peripheral surface is pulled according to a weak tensile force, the phenomenon of the plate thickness is suppressed, and cracking and necking are prevented.

  Further, the concentric tube expansion process has a specific outer diameter, that is, larger than the orthogonal distance from the axial core of the raw tube portion to the low expanded peripheral surface of the expanded tube portion, and from the axial center of the expanded tube portion to the higher expanded peripheral surface of the expanded tube portion. By concentrically expanding the end of the tube section to an outer diameter smaller than the orthogonal distance of the end, the end of the expanded tube section contacts the eccentric inner surface of the eccentric die with the low-expanded peripheral surface of the end section. The end portion can be bent toward the highly expanded peripheral surface. Here, “the orthogonal distance from the core of the tube portion to the low tube expansion peripheral surface of the tube expansion portion” is the length obtained by subtracting the eccentric amount from the outer diameter of the tube expansion portion, The term “orthogonal distance from the tube expansion portion to the high expansion peripheral surface” means the length obtained by subtracting the eccentric amount from the outer diameter of the tube expansion portion. The end portion of the raw tube portion is bent with a portion of the low-expansion peripheral surface, for example, an intermediate expansion boundary connecting the end portion and the raw tube portion, against the eccentric inner surface of the eccentric die, and the portion as a fulcrum. .

  The concentric die, concentric punch, eccentric die and eccentric punch used in each step of the present invention may have the same configuration as in the prior art, but in order to form a concentric tube-expanded end having a specific outer diameter, The diameter of the concentric die is specified. That is, the concentric die used in the manufacturing method of the present invention is larger than the orthogonal distance from the axial core of the raw tube portion to the low expansion peripheral surface of the expanded portion, and from the axial center of the expanded tube portion to the high expanded peripheral surface of the expanded portion. The structure has a concentric inner surface with a radius smaller than the orthogonal distance. As a result, the end portion of the raw tube portion that has been subjected to the concentric tube expansion process using the concentric die having the radius must always contact the eccentric inner surface of the eccentric die with the low tube expansion peripheral surface, and the end portion as a whole. It can be bent toward the highly expanded peripheral surface.

  The manufacturing method of the eccentric tube expansion according to the present invention makes it possible to manufacture the eccentric tube expansion in which the occurrence of cracking and necking is suppressed without reducing the production efficiency and without increasing the cost. This is an effect of suppressing the plate thickness from being reduced by pulling and expanding the tube in a state where a compressive force is generated on the highly expanded peripheral surface in the eccentric tube expanding step. In addition, in the present invention, it is not necessary to prepare a special die or punch in order to obtain the above-described effect, and it is not necessary to repeat one or both of the coaxial tube expansion step and the eccentric tube expansion step a plurality of times. That is, this invention provides the manufacturing method of the eccentric expansion pipe | tube which has suppressed the crack and necking in eccentric expansion pipe | tube, reducing manufacturing cost, and was excellent in cost effectiveness.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is an axial sectional view of a concentric die 31 and an end portion 11 of the raw tube portion 1 showing a stage after the concentric pipe expanding process, and FIG. 2 is an eccentric die 41 showing a stage before starting the eccentric pipe expanding process. FIG. 3 is a sectional view in the axial direction of the end portion 11 of the raw tube portion 1, and FIG. 3 is a sectional view in the axial direction of the eccentric die 41 and the expanded tube portion 2 showing the stage after the eccentric tube expansion step. This example is an example of the manufacturing procedure of the eccentric tube expansion which forms the tube expansion part 2 eccentrically downward in FIG. 3 through the concentric tube expansion step once and the eccentric tube expansion step once.

  In the concentric tube expanding step of the present invention, the dimensions of the concentric die 31 are specified with respect to the expanded portion of the eccentric tube expanded after the eccentric tube expanding step, and in addition to the conventionally known concentric tube expanding step. There is no change. Specifically, as shown in FIG. 1, a larger distance Ds (see FIG. 3) from the axial center Oo of the tube 1 to the low tube expansion peripheral surface 21 of the tube expansion 2, In the range of the concentric inner surface 311 of the concentric die 31 having the concentric inner surface 311 having a radius De smaller than the orthogonal distance Db (see FIG. 2) from the axial center Oo to the highly expanded peripheral surface 22 of the expanded portion 2. The concentric punch 32 is press-fitted into the end portion 11 of the base tube portion 1 with the end portion 11 of the first tube 11 protruding, and the end portion 11 is concentrically expanded.

  In this concentric tube expanding step, the end portion 11 of the base tube portion 1 is uniformly concentric expanded in the circumferential direction, so that the plate thickness of the end portion 11 is uniform in the circumferential direction. For this reason, the tip of the concentric punch 32 is a concentric taper surface 321 so that the end portion 11 of the blank tube portion 1 to be press-fitted is uniformly pushed in the circumferential direction. In addition, the end portion 11 of the tube portion 1 to be expanded concentrically in this way has an intermediate portion 12 connecting the tube portion 1 and the expanded end portion 11 with a simple annular tube boundary edge 13 and an expanded tube. The boundary edge 23 is parallel and formed in a substantially frustoconical shape. Thus, the concentric tube expansion process of the present invention is not different from the conventional one in appearance. This means that the present invention can be implemented with equipment similar to the conventional one, and has the effect of suppressing an increase in manufacturing cost.

  In the manufacturing method of the present invention, as described above, the radius De of the concentric inner surface 311 of the concentric die 31 is specified in relation to the expanded pipe portion 2 to be a product, so that the raw pipe portion 1 in the eccentric expanded tube process. The end 11 of the tube can be bent to compress the highly expanded tube side in the axial direction. Specifically, as shown in FIG. 2, the core tube portion 1 that has been subjected to concentric tube expansion processing in the range of the eccentric inner surface 411 of the eccentric die 41 having the eccentric inner surface 411 that is equal to the outer shape of the tube expansion portion 2. When the end 11 is projected, the low expansion peripheral surface 21 of the end 11, specifically, the expansion boundary edge 23 is applied to the eccentric inner surface 411, and the end 11 is inclined toward the high expansion peripheral surface 22. In the eccentric tube expanding step, the eccentric punch 42 is press-fitted into the end portion 11 with the end portion 11 of the base tube portion 1 bent, and the highly expanded peripheral surface 22 is compressed in the axial direction in the axial direction. The end portion 11 is subjected to eccentric tube expansion processing.

  In the stage before starting the eccentric tube expansion process, the end portion 11 of the tube portion 1 is orthogonally spaced from the axis Oo of the tube portion 1 to the low tube expansion peripheral surface 21 of the tube expansion portion 2 (see FIG. 3). Since the concentric pipe expansion is performed to a radius De larger than the orthogonal distance Db (see FIG. 3) from the axis Oo of the base pipe part 1 to the high pipe expansion peripheral surface 22 of the pipe expansion part 2, the end part 11 is When protruding from the eccentric inner surface 411 of the eccentric die 41, the peripheral surface of the end portion 11 on the low tube expansion side, particularly the tube expansion boundary edge 23 of the intermediate portion 12 inevitably hits the eccentric inner surface 411. The end 11 is bent toward the high expansion side as long as the peripheral surface of the end 11 on the high expansion side does not contact the eccentric inner surface 411. The appropriate amount of bending of the end portion 11 is the amount of eccentricity (difference between the axial center Oo of the base tube portion 1 and the axial core Oe of the expanded portion 2), the length from the expanded boundary edge 23 to the end face of the end portion 11. In addition, the amount of eccentricity is the product of the angle in the bent state and the length from the pipe expansion boundary edge 23 to the end face of the end 11, although it varies depending on the material of the end 11 of the tube 1 and the initial plate thickness. A degree equal to is preferable.

  Such bending of the end portion 11 compresses the highly expanded peripheral surface 22 of the expanded tube portion 2 in the axial direction, and the eccentric expanded tube is a plastic working that extends by pulling the highly expanded peripheral surface 22 in the axial direction. For this reason, the pulling force is reduced by the compressive force, and the reduction in the plate thickness of the highly expanded peripheral surface 22 is suppressed. Similarly, the low tube expansion side of the end portion 11 is compressed by the eccentric tube expansion process while being pulled. That is, according to the present invention, each of the high tube expansion side and the low tube expansion side is in a relationship of being plastically deformed into a product form by the eccentric tube expansion process while the tensile force or the compression force is similarly reduced. As a result, the eccentric pipe expansion by the manufacturing method of the present invention suppresses the difference in plate thickness between the low pipe expansion peripheral surface 21 and the high pipe expansion peripheral surface 22 as compared with the conventional case, and the structural strength of the pipe expansion portion 2 subjected to the eccentric pipe expansion processing. There is also an advantage that can be averaged in the circumferential direction. This is a positive effect according to the present invention in addition to preventing cracking and necking.

  The specific eccentric tube expansion process is as follows. The end portion 11 subjected to concentric tube expansion is inclined in the eccentric inner surface 411 of the eccentric die 41, but the eccentric punch 42 is press-fitted in parallel with the axial core Oo of the raw tube portion 1. The eccentric punch 42 is formed with an eccentric taper surface 421 at the tip, and has an axis that coincides with the axis Oe of the tube expansion portion 2. From this, the low-expansion peripheral surface 21 can be obtained by plastic deformation in which the above-described tensile force or compression force is reduced on the low-expansion side and the high-expansion side only by press-fitting the eccentric punch 42 into the inclined end portion 11 as described above. Further, the highly expanded peripheral surface 22 is formed. Then, as the tube expansion portion 2 is formed by press-fitting the eccentric punch 42, a newly inclined tube expansion boundary edge 23 is formed while plastically deforming the intermediate portion 12, and an eccentric tube expansion as shown in FIG. 3 is obtained. .

It is an axial sectional view of the end of a concentric die and a raw pipe part showing the stage which finished the concentric pipe expansion process. It is an axial direction sectional view of an end of an eccentric die and a raw pipe part showing a stage before starting an eccentric pipe expansion process. It is an axial direction sectional view of an eccentric die and a pipe expansion part showing a stage which finished an eccentric pipe expansion process.

Explanation of symbols

1 Elementary tube
11 End 2 Expanded part
21 Low expansion peripheral surface
22 High expansion peripheral surface
31 Concentric die
311 Concentric inner surface
32 Concentric punch
41 Eccentric die
411 Eccentric inner surface
42 Eccentric punch
De Concentric die radius
Ds Orthogonal distance from the core of the tube section to the low expansion surface of the expanded section
Db Orthogonal distance from the axial center of the tube section to the highly expanded peripheral surface of the expanded section
Oo Shaft core
Oe Expanded shaft axis

Claims (2)

A method of manufacturing an eccentric tube expansion that is plastically deformed into an expanded tube portion in which an end portion of the raw tube portion is eccentric by a concentric tube expansion step and an eccentric tube expansion step,
The concentric tube expansion process is performed with the same radius that is larger than the orthogonal distance from the axis of the core pipe portion to the low expansion peripheral surface of the expansion portion and smaller than the orthogonal distance from the axis of the core tube portion to the high expansion peripheral surface of the expansion portion. A concentric punch is press-fitted into the end portion of the core tube portion in a state where the end portion of the core tube portion projects into the range of the concentric inner surface of the concentric die having a core inner surface, and the end portion is concentric expanded. Processed
The eccentric tube expanding step projects the end portion of the core tube portion subjected to concentric tube expansion into the range of the eccentric inner surface of the eccentric die having the eccentric inner surface equal to the outer shape of the expanded tube portion, and the low tube expansion of the end portion An eccentric punch is press-fitted into the end portion while the end portion is inclined toward the highly expanded peripheral surface of the end portion while the peripheral surface is applied to the eccentric inner surface, and the end portion is subjected to eccentric tube expansion processing. A method of manufacturing an eccentric tube having a feature. A concentric die used for the concentric tube expansion step of the eccentric tube expansion method comprising a concentric tube expansion step and an eccentric tube expansion step,
A concentric die is a concentric core having a radius that is greater than the orthogonal distance from the core of the core tube portion to the low expansion peripheral surface of the tube expansion portion and smaller than the orthogonal distance from the axis of the core tube portion to the high expansion peripheral surface of the tube expansion portion. A concentric die having an inner surface.

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