JP2018138306A - Forming method of inside flange - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a forming method of an inside flange of stably forming the inside flange into a prescribed shape in the forming method of the inside flange forming the inside flange by bending the end of a cylindrical pipe in the inside direction.SOLUTION: A forming method of an inside flange includes: a taper forming step of forming a taper part 20 by bending and clamping an end 10c of a pipe by using a die 16 having an outside restraining surface 17 in parallel with a shaft core of the pipe 10 and an outside inclined surface 18 inclined with respect to the outside restraining surface 17, and a core grid 12 having an inside restraining surface 13 in parallel with a shaft core of the pipe and an inside inclined surface 14 inclined with respect to the shaft core of the pipe; and a flange forming step of forming an inside flange 3 by bending and clamping the taper part 20 by using a die 26 having an outside restraining surface 27 in parallel with the shaft core of the pipe and an outside orthogonal surface 28 orthogonal to the shaft core of the pipe, and a core grid 22 having an inside restraining surface 23 in parallel with the shaft core of the pipe and an inside orthogonal surface 24 orthogonal to the shaft core of the pipe.SELECTED DRAWING: Figure 3

Description

  The present invention relates to a method for forming an inner flange.

  Conventionally, as a method of forming an inner flange formed by bending the end of a cylindrical pipe in the inner direction of the pipe so as to be orthogonal to the axial center of the pipe, the main body of the pipe is outside by a die. The method is known in which the punch is pressed from the outside in the axial direction of the pipe to the end of the pipe and the end of the pipe is bent inward (see Patent Document 1). Hereinafter, this is referred to as Prior Art 1.

  In addition, the die and the punch are fixed at a predetermined distance, the end of the cylindrical pipe is press-fitted into the gap between the die and the punch, the end of the pipe is drawn, and the inner flange is drawn. There is known a method of molding (see Patent Document 2). Hereinafter, this is referred to as Prior Art 2.

Japanese Patent No. 4352777 JP 2003-290853 A

  In the molding method of the prior art 1, the pipe body is restrained from the outside by a die and the punch is pressed from the outside in the axial direction of the pipe, so that the processing of the end of the pipe proceeds and the diameter reduction ratio is large. Then, the processing limit is exceeded, the material escapes in the inner direction of the pipe, and the inner flange 102 of the pipe 101 may be deformed into a wave shape as shown in FIG.

  Further, in the molding method of the above prior art 2, since the end of the cylindrical pipe is press-fitted into the gap between the die and the punch, the outer surface of the pipe is rubbed with the die, and the outer surface of the pipe is scratched. As a result, the inner surface of the die may be worn.

  SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to propose a method for forming an inner flange that solves the above problems.

In order to solve the above-described problems, the present invention provides an end portion of a pipe having an outer constraining surface parallel to the axis of the pipe, a die having an outer inclined surface inclined with respect to the outer constraining surface, A taper forming step of forming a taper portion by bending and clamping by using a metal core having an inner constraining surface parallel to the axis of the pipe and an inner inclined surface inclined with respect to the axis of the pipe;
The taper portion, an outer constraining surface parallel to the axis of the pipe, a die having an outer orthogonal surface orthogonal to the axis of the pipe, an inner constraining surface parallel to the axis of the pipe, A flange forming step of forming an inner flange by bending and clamping using a metal core having an inner orthogonal surface orthogonal to the axis of the pipe,
It is a forming method of an inner flange characterized by having.

  Further, the taper forming step may be performed a plurality of times, and the angle of the tapered portion with respect to the axis of the pipe may be gradually increased.

  In the present invention, the end portion of the pipe is bent and pressed using a die having an outer restraint surface and an outer inclined surface, and a core metal having an inner restraint surface and an inner inclined surface, thereby forming a tapered portion. The taper portion is bent and pressed using a die having an outer restraint surface and an outer orthogonal surface and a core metal having an inner restraint surface and an inner orthogonal surface, thereby forming an inner flange. The inner flange having a predetermined shape can be stably formed without buckling the part.

  Moreover, it can suppress that the edge part of a pipe does not rub with a metal core or a die | dye, and a damage | wound arises in the inner and outer surface of a pipe. Moreover, it is possible to reduce the wear of the cored bar and the die.

The perspective view of the molded article shape | molded by Example 1 of this invention. The longitudinal cross-sectional view of the pipe used for Example 1 of this invention. It is a figure for demonstrating the shaping | molding method of the inner side flange which concerns on Example 1 of this invention, and the longitudinal cross-sectional view of the state which externally fitted the pipe of FIG. 2 to the taper-formed metal core. The longitudinal cross-sectional view of the state which lowered | hung the taper formation die | dye from the state of FIG. The longitudinal cross-sectional view of the state which raised the taper formation die | dye from the state of FIG. The longitudinal cross-sectional view of the state which carried out the external fitting of the pipe which formed the taper part to the flange formation metal core. The longitudinal cross-sectional view of the state which lowered | hanged the flange formation die from the state of FIG. The longitudinal cross-sectional view of the state which raised the flange formation die from the state of FIG. The longitudinal cross-sectional view of the molded article of FIG. The longitudinal cross-sectional view for demonstrating the taper formation process in Example 2 of this invention. The longitudinal cross-sectional view of the state which further bent the preliminary taper part shape | molded in FIG. 10, and shape | molded the taper part. The perspective view of the molded article shape | molded by the prior art 1. FIG.

  A mode for carrying out the present invention will be described based on an embodiment shown in the drawings.

[Example 1]
FIG. 1 shows a perspective view of a molded product 1 molded by using the inner flange molding method according to the first embodiment of the present invention.

  The molded product 1 is formed of a metal material, and the main body 2 and one end of the main body 2 are arranged in the direction of the axis XX side (inner side) of the main body 2, and the axis X- It has an inner flange 3 that is bent so as to be orthogonal to X. The main body 2 is formed in a cylindrical shape or a cylindrical shape of an arbitrary polygon such as a quadrangle, and in this embodiment, as shown in FIG.

  Next, a method for forming the inner flange 3 will be described.

  First, as shown in FIG. 2, a metal cylindrical shape having an arbitrary length in the axis XX direction, a circular cross section, and the same outer diameter throughout the axis XX direction. The pipe 10 is prepared. In addition, although the cross-sectional shape of the pipe 10 is formed in a perfect circle shape in this embodiment, it may be formed in a polygonal shape such as a quadrilateral other than the perfect circle shape. The pipe 10 has a hollow portion 10a in which both ends in the direction of the axis XX are opened.

  Next, as shown in FIG. 3, the pipe 10 is externally fitted to a tapered cored bar 12 erected on the base 11, that is, the tapered cored bar 12 is inserted into the hollow portion 10 a of the pipe 10, The pipe 10 is attached so that the end surface of the other end portion 10 b contacts the base 11.

  The tapered cored bar 12 has a cylindrical inner restraint formed in parallel with the axial center XX of the pipe 10 (axial core of the tapered cored bar 12) at the tip portion on the tapered forming die 16 side described later. A surface 13 is formed, and a tapered inner inclined surface 14 that is inclined with respect to the axial center XX of the pipe 10 and is reduced in diameter toward the tip is formed at the tip of the inner restraining surface 13. 12 is formed continuously with the inner restraint surface 13 over the entire circumference.

  The end surface of one end portion 10c of the pipe 10 is located outside the inner inclined surface 14 and is located at the same position as the tip of the inner inclined surface 14 or on the far side.

  The taper forming die 16 is provided so as to be movable in the axial direction of the taper core 12, and the shaft core is positioned coaxially with the axis of the taper core 12 as shown in FIG. 3. Is arranged. Further, in the state shown in FIG. 3, the taper forming die 16 is separated from the taper forming core metal 12 by a predetermined distance. The taper forming die 16 is formed with a cylindrical outer restraint surface 17 formed in parallel with the axis XX of the pipe 10, and on the opposite side of the outer restraint surface 17 from the taper core 12 side, A tapered outer inclined surface 18 that is inclined with respect to the outer constraining surface 17, that is, the axis XX of the pipe 10 and increases in diameter toward the tapered cored bar 12, extends over the entire circumference of the taper forming die 16. It is formed continuously with the outer restraint surface 17.

  The inclination angle α of the inner inclined surface 14 and the outer inclined surface 18 with respect to the axis XX of the pipe 10 is set to be the same. The inclination angle α depends on the material of the pipe 10, the thickness, the diameter reduction rate, and the like. Set as desired.

  The taper forming die 16 is formed with a taper-shaped guide surface 19 which is located on the taper forming core 12 side of the outer restraining surface 17 and whose diameter increases toward the taper forming core 12 side.

  Next, the taper forming die 16 is moved along the axis XX of the pipe 10 in the direction of the taper core 12 as shown in FIG. One end portion 10c of the pipe 10 is formed between the inner inclined surface 14 of the tapered metal core 12 and the outer inclined surface 18 of the taper forming die 16 in the axial XX side direction of the pipe 10, that is, in the inner direction. The taper portion 20 is formed by bending and clamping.

  When the tapered portion 20 is formed, the inner and outer peripheral surfaces of the pipe 10 in the vicinity of the tapered portion 20 are restrained by the inner restraint surface 13 of the taper forming core metal 12 and the outer restraint surface 17 of the taper forming die 16. And the deformation | transformation of the taper part 20 vicinity in the part of the pipe 10 used as the main-body part 2 can be suppressed.

  Next, as shown in FIG. 5, the taper forming die 16 is retracted in a direction away from the taper forming core 12 by a moving means (not shown), and the pipe 10A in which the taper portion 20 is formed is tapered. Take out from. The step of forming the tapered portion 20 is referred to as a taper forming step.

Next, as shown in FIG. 6, the pipe 10 </ b> A formed with the tapered portion as described above is formed with a flange erected on the base 21 from the other end portion 10 b side opposite to the tapered portion 20. The core metal 22 is inserted into the hollow portion 10a of the pipe 10A, and the pipe 10A is externally fitted to the flange-formed core metal 22. Further, the end face of the other end 10b of the pipe 10A is
It abuts on the base 21.

  On the other end side of the flange-formed core metal 22, a cylindrical inner restraint surface 23 formed in parallel with the axis XX of the pipe 10A (axis core of the flange-formed core metal 22) is formed. An inner orthogonal surface 24 that is orthogonal to the axis XX of the pipe 10 is formed continuously at the tip portion of the pipe 10 over the entire circumference of the flange-forming metal core 22. As shown in FIG. 6, the taper portion 20 protrudes toward the front side from the inner orthogonal surface 24.

  A flange-forming die 26 is provided so as to be movable in the axial direction of the flange-forming metal core 22 and is disposed coaxially with the flange-forming metal core 22 as shown in FIG. In the state shown in FIG. 6, the flange forming die 26 is separated from the flange forming core metal 22 by a predetermined distance.

  The flange forming die 26 is formed with a cylindrical outer restraint surface 27 formed in parallel with the axis XX of the pipe 10A, and on the opposite side of the outer restraint surface 27 from the flange forming core metal 22 side, the pipe is formed. An outer orthogonal surface 28 orthogonal to the axis XX of 10A is formed continuously with the outer restraint surface 27 over the entire circumference of the flange forming die 26. The inner orthogonal surface 24 of the flange-forming metal core 22 and the outer orthogonal surface 28 of the flange-forming die 26 are formed in parallel. The flange forming die 26 is formed with a tapered guide surface 29 that is located on the flange forming core 22 side of the outer restraining surface 27 and that increases in diameter toward the flange forming core 22 side.

  Next, when the flange forming die 26 is moved in the direction of the flange forming core metal 22 along the axis XX of the pipe 10A as shown in FIG. The portion 20 is further bent in the axial center XX side direction of the pipe 10A, that is, the inner side direction, between the inner orthogonal surface 24 of the flange-forming metal core 22 and the outer orthogonal surface 28 of the flange-forming die 26. At the same time, the inner flange 3 is formed by being pinched. The step of forming the inner flange 3 is referred to as a flange forming step.

  When the inner flange 3 is formed, the inner and outer peripheral surfaces of the pipe 10 </ b> A in the vicinity of the inner flange 3 are restrained by the inner restraining surface 23 of the flange-forming metal core 22 and the outer restraining surface 27 of the flange-forming die 26. And the deformation | transformation of the inner flange 3 vicinity in the part of the pipe 10A used as the main-body part 2 can be suppressed.

  Next, as shown in FIG. 8, the flange-forming die 26 is retracted in a direction away from the flange-forming metal core 22 by a moving means (not shown), and the molded product 1 on which the inner flange 3 is formed is flange-formed metal core. Then, the molded product 1 shown in FIGS. 1 and 9 is obtained.

  As described above, the end portion of the pipe 10 is bent inwardly between the inner inclined surface 14 of the taper-formed core metal 12 and the outer inclined surface 18 of the taper-forming die 16, and is pinched to be tapered. 20, and the taper portion 20 is further bent inward and clamped between the inner orthogonal surface 24 of the flange-forming metal core 22 and the outer orthogonal surface 28 of the flange-forming die 26. By forming the inner flange 3, it is possible to stably form the inner flange 3 having a predetermined shape without buckling the end of the pipe 10. Moreover, it can suppress that the edge part of the pipe 10 does not rub against the metal cores 12 and 22 and the dies 16 and 26, and a damage | wound arises in the inner and outer surface of the molded article 1. Further, it is possible to reduce the wear of the core bars 12 and 22 and the dies 16 and 26.

  In addition, in the figure explaining the said Example 1, although illustrated so that the dies 16 and 26 may be arrange | positioned upwards with respect to the metal cores 12 and 22, the positional relationship of the dies 16 and 26 with respect to the metal cores 12 and 22 is shown. Can be arbitrarily set as long as the metal cores 12 and 22 and the dies 16 and 26 are relatively positioned in the lateral direction as long as they can move in the axial direction XX of the pipes 10 and 10A.

[Example 2]
In the first embodiment, the taper portion 20 is formed by one taper forming step. However, the taper portion is gradually increased by a plurality of taper forming steps to gradually increase the inclination angle of the pipe 10 with respect to the axis XX. The inclination angle β may be as follows.

For example, as shown in FIG. 10, a first taper portion 35 having an inclination angle β ₀ is formed on one end portion 10 c of the pipe 10 using a first flange-forming cored bar 32 and a first flange-forming die 33. after, as shown in FIG. 11, a second flange formed metal core 36 with a second flange forming die 37, the first tapered portion 35, and more deeply bent, it size of the inclination than the inclination angle beta ₀ A tapered portion 40 having an inclination angle β may be formed.

Thus, for example, the taper portion 40 having a predetermined tilt angle β may be formed by gradually increasing the tilt angles of the taper portions 35 and 40 through two taper forming steps. The inclination angles β ₀ and β are arbitrarily set according to the material, thickness, diameter reduction rate, and the like of the pipe 10.

  Since the other structure is the same as that of the first embodiment, the description thereof is omitted.

  Also in the second embodiment, the same effects as in the first embodiment are obtained.

  In general, as the length of the inner flange 3 to be formed becomes longer, the diameter reduction rate at the inner portion of the inner flange 3 becomes higher, and buckling and cracking are likely to occur. By bending the one end portion 10c of the pipe 10 gradually and holding pressure by the taper forming step, the occurrence of buckling and cracking is suppressed, and the inner flange 3 having a predetermined shape is stably formed. Can be formed, and processing becomes easy.

[Example 3]
In the first and second embodiments, the metal cores 12 and 22 are fixed, and the dies 16 and 26 are moved in the axial center XX direction of the pipes 10 and 10A using the moving means. , 26 may be fixed, and the metal cores 12, 22 may be moved in the direction of the axial core XX of the pipe 10, 10A, or both the metal cores 12, 22 and the dies 16, 26 may be moved. You may do it.

  Since other structures are the same as those of the first and second embodiments, description thereof is omitted.

  In the third embodiment, the same effects as in the first and second embodiments are obtained.

DESCRIPTION OF SYMBOLS 3 Inner flange 10 Pipe 12, 32, 36 Tapered core metal 13 Inner restraint surface 14 Inner inclined surface 16, 33, 37 Taper formation die 17 Outer restraint surface 18 Outer inclined surface 20, 35, 40 Taper part 22 Flange formed core metal 23 inner restraint surface 24 inner perpendicular surface 26 flange forming die 27 outer restraint surface 28 outer orthogonal surface

Claims (2)

An end portion of the pipe, an outer constraining surface parallel to the axis of the pipe, a die having an outer inclined surface inclined with respect to the outer constraining surface, an inner constraining surface parallel to the axis of the pipe; Using a metal core having an inner inclined surface that is inclined with respect to the axis of the pipe, a taper forming step of forming a taper portion by bending and clamping,
The taper portion, an outer constraining surface parallel to the axis of the pipe, a die having an outer orthogonal surface orthogonal to the axis of the pipe, an inner constraining surface parallel to the axis of the pipe, A flange forming step of forming an inner flange by bending and clamping using a metal core having an inner orthogonal surface orthogonal to the axis of the pipe,
A method for forming an inner flange, comprising: The method for forming an inner flange according to claim 1, wherein the taper forming step is performed a plurality of times to gradually increase the angle of the tapered portion with respect to the axis of the pipe.

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