JPH0730171Y2 - Half-moon crushing structure of cylindrical pipe - Google Patents

Description

[Detailed Description of the Invention] [Industrial application] The present invention relates to a half-moon crushing type structure of a cylindrical pipe, and in particular, when crushing a cylindrical pipe constituting a front seat back frame of an automobile into a half-moon shape, The present invention relates to the improvement of the half-moon crush type structure of a cylindrical pipe, which is suitable for ensuring the flatness of the crushed portion and improving the fit with the mating component.

[Conventional technology]

Conventionally, a front seat back frame which is required to have a torsional rigidity has a pipe structure as shown in FIG. 4, and welding is often used for connecting pipes.

That is, in FIG. 4, 52 is a frame pipe, 54 is a lower pipe, 56 is an S-shaped spring, and 58 is a hobbling wire for fixing the seat skin.

Usually, the method of flattening the pipe 53 completely is adopted as shown in FIG. 5, but when the above-mentioned torsional rigidity is strongly required, as shown in FIG. The method of crushing half a month is adopted.

The mold structure for making this half-moon crushed pipe 55 is
It is composed of an upper die 57 and a lower die 59 as shown in FIG.

That is, the lower surface 572 of the upper die 75 is flat, whereas the upper surface 592 of the lower die 59 is provided with a recess 594 that substantially follows the outer shape of the pipe 55.

In other words, the upper surface 592 of the lower mold 59 is provided with a clearance for the outer shape of the pipe 55. Note that this escape (that is, the radius of the recess 594) R is relative to the radius r of the pipe 55.
R = r + 3 to 4 mm.

Further, a relief L is provided between the upper die 592 and the upper die 592 on the upper surface 592 of the lower die 59. This L is L = 2 to 3 mm.

The relief R, the boundary curved surface m, and the relief L form a die structure that prevents the outer surface of the pipe 55 from being scratched.

FIG. 8 is a cross-sectional view showing a half-moon crushing molding process in time series, FIG. 9 is a perspective view showing the shape of a frame pipe molded by a conventional mold, and FIG. 10 is a joint portion of the frame pipe and the lower pipe. FIG.

[Problems to be solved by the invention]

However, when a conventional mold is used, there are no pressing flaws on the outer periphery of the frame pipe 55, but on the other hand, due to the recess 552 formed in the frame pipe 55 during molding, there is a gap between the lower pipe 54 and the lower pipe 54 as shown in FIG. There was a problem that S was generated.

The reason for this will be briefly described. From FIG. 8 (B) to (C)
When the molding proceeds, the circumference of the frame pipe 55 basically does not change even if the deformation proceeds.

Therefore, in FIG. 8B, after the frame pipe 55 is adapted to the relief R of the lower die 59, as the contact point pitch 1 with the upper die 57 expands, the bent portion 557 of the front portion thereof is Entrainment inward is promoted.

In this way, the part 55 not constrained by the lower mold 59
2 buckles downward as shown in FIG. 8 (C). The upper die 57 does not deform upward.

Then, once buckled, the depression 552 described above is promoted by the pressurization of the upper die 57, and the flatness cannot be ensured.

As a result, a gap S is formed between the lower pipe 54 and the lower pipe 54 described above. The gap S is about 2 mm, although it depends on the amount of half-moon crushing.

For the above reasons, the conventional mold structure has a problem that when the frame pipe 55 and the lower pipe 54 are welded, quality defects such as burn-through and defective penetration occur.

Then, this invention aims at ensuring the flatness of a crushed part by canceling the buckling force which acts on a half-moon crushed part, when crushing a cylindrical pipe for half a month.

[Means for solving problems]

Therefore, the present invention comprises a lower mold having a concave portion having a half-moon shape on the upper surface and an upper mold having a planar lower surface, and a cylindrical pipe is sandwiched between the lower mold and the upper mold to apply pressure. By this, in a half-moon-crushing structure of a cylindrical pipe for forming a cylindrical pipe into a half-moon shape, the recess of the lower mold is formed to be substantially the same as the radius of the cylindrical pipe, and at the bottom of the upper mold, A recess having a radius larger than the radius of the pipe and having a width equal to or smaller than the diameter of the cylindrical pipe is formed.

[Action]

By the means described above, the cylindrical pipe is set in the recess of the lower mold, and while the cylindrical pipe is firmly restrained by the recess, pressure is applied by the upper mold to form the cylindrical pipe in a half-moon shape. At this time, the recess provided in the upper mold cancels the buckling force that acts on the half-moon crushed portion of the cylindrical pipe, and the cylindrical pipe is restrained by the recess of the lower mold, so that both ends of the half-moon crushed cylindrical pipe are positively affected. To form a brim and to apply a tensile force to the half-moon crushed part by the tensile force generated in this brim, the cylindrical pipe is formed in a half-moon shape while ensuring the flatness of the half-moon crushed part. To be done.

〔Example〕

An embodiment of the present invention will be described below in detail with reference to the drawings.

FIG. 1 is a cross-sectional view showing a schematic structure of a half-moon crushing type structure of a cylindrical pipe according to the present invention, FIG. 2 is a cross-sectional view showing the shape and size of a recess formed in an upper mold, and FIG. 3 is the present invention. FIG. 6 is a cross-sectional view showing a cylindrical pipe molded by the half-moon crushing structure according to the present invention together with a lower mold.

A half-moon crushing type structure (hereinafter referred to as a half-moon crushing type structure) 1 of a cylindrical pipe includes a lower mold 2, an upper mold 4, and a recess 6 formed in the upper mold 4.

The lower mold 2 constitutes one of the molding dies, and has a recess 24 having a half-moon shape formed on the upper surface 22.

The radius R _{1 of the} recess 24 is such that the cylindrical pipe 12 having a substantially perfect circular shape that is crushed in half a month is tightly inserted.
It is the same as the radius R _{2 of} 12.

Further, the clearance L ₁ between the upper surface 22 of the lower mold 2 and the upper mold 4 is L ₁ =
It is set to 0.

The upper die 4 constitutes the other of the forming dies, and the lower surface 42 is formed in a substantially flat shape.

The lower surface 42 is provided with a recess 6 having a radius R ₃ which is larger than the radius R ₂ of the cylindrical pipe 12 and a width W which is equal to or smaller than the diameter of the cylindrical pipe 12.

In this embodiment, the radius R _{3 of the} recess 6 is about R ₃ = 50 mm, and the maximum recess depth d from the lower surface 42 of the upper die 4 is about d = 1 mm.

The outer diameter of the cylindrical pipe 12 is 19.1 to 25.4 mmφ, and the plate thickness t is t = 1.2 to 2.0 mm.

The operation of the embodiment according to the above configuration will be described below.
Set the cylindrical pipe 12 in the recess 24 of the
Is R ₁ = R ₂ and the difference between the center positions of R ₁ and R ₂ h = 0,
While the cylindrical pipe 12 is firmly restrained, the upper mold 4 presses the half-moon crushed portion 122 to form the cylindrical pipe 12 in a half-moon shape.

It should be noted that the amount of this pressing is the upper surface 22 of the lower mold 2 and the lower surface of the upper mold 4.
Until the gap δ with 42 becomes about δ = t + 2 mm.

At this time, when the cylindrical pipe 12 is crushed for half a month, its circumferential length basically does not change before and after molding. Therefore, during molding, the half-moon crushed portion 122 of the cylindrical pipe 12 is
However, once recessed in the direction of arrow P in FIG. 1, it cannot be expected to return unless a force is applied in the opposite direction.

Therefore, in the present embodiment, the recess 6 formed on the lower surface 42 of the upper die 4 cancels the generation of the buckling force acting on the half-moon crushed portion 122 in the direction of the arrow P.

Furthermore, since the cylindrical pipe 12 is restrained by the lower mold 2,
As a result, both ends of the cylindrical pipe 12 that is crushed for half a month are positively projected to form the brim portion 126.
Along with the formation of 26, a tensile force is applied to the half-moon crushed portion 122.

In this way, the cylindrical pipe 12 can be molded into a half-moon shape while ensuring the flatness of the half-moon crushed portion 122.

As a result, the flatness of the half-moon crushed portion can be ensured even in the area where the core metal cannot be inserted.

The specific embodiment of the present invention has been described above, but the present invention is not limited to this, and various other modes that can be implemented by those skilled in the art are conceivable within the scope of the claims of the utility model.

For example, although the cylindrical pipe has a substantially perfect circular shape in the above embodiment, it may have an elliptical shape instead of a perfect circular shape.

[Effect of device]

As described above, the concave portion of the lower die of the cylindrical pie according to the present invention is formed substantially the same as the radius of the cylindrical pipe, and the lower surface of the above-mentioned die has a radius larger than the radius of the cylindrical pipe, and Since a recess having a width equal to or smaller than the diameter of the cylindrical pipe is formed, when the cylindrical pipe is crushed in half a month, the buckling force acting on the half-moon crushed portion is canceled and a tensile force is applied to the half-moon crushed portion. The flatness of the half-moon crushed part can be secured.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing a schematic structure of a half-moon crushing type structure of a cylindrical pipe according to the present invention, FIG. 2 is a cross-sectional view showing the shape and size of a recess formed in an upper mold, and FIG. 3 is the present invention. FIG. 4 is a sectional view showing a cylindrical pipe molded by the half-moon crushing type structure together with a lower mold, FIG. 4 is a front view showing a schematic configuration of a front seat back frame, and FIG. 5 is a schematic crushing structure of a frame pipe. 6 is a perspective view shown in FIG.
FIG. 7 is a perspective view schematically showing a half-moon crushing structure of a frame pipe, FIG. 7 is a sectional view schematically showing a conventional half-moon crushing structure, and FIG. 8 is a half-moon crushing molding process using a conventional mold. FIG. 9 is a cross-sectional view showing the above in chronological order, FIG. 9 is a perspective view showing the shape of a frame pipe molded by a conventional mold, and FIG. 10 is a cross-sectional view showing a joint portion of the frame pipe and the lower pipe. 1 …… Cylindrical pipe half-moon crushing structure 2 …… Lower mold 4 …… Upper mold 6,24 …… Concave 12 …… Cylinder pipe 22 …… Upper surface 42 …… Lower surface

Claims (1)

[Scope of utility model registration request] 1. A lower mold having a half-moon shaped recess formed on the upper surface and an upper mold having a planar lower surface, and a cylindrical pipe is sandwiched between the lower mold and the upper mold to apply pressure. By this, in a half-moon-crushing structure of a cylindrical pipe for forming a cylindrical pipe into a half-moon shape, the recess of the lower mold is formed to be substantially the same as the radius of the cylindrical pipe, and at the bottom of the upper mold, A half-moon crushing structure for a cylindrical pipe, characterized in that a recess having a radius larger than that of the pipe and having a width equal to or smaller than the diameter of the cylindrical pipe is formed.