JPS6186036A - Flattening work method of pipe end and it's die - Google Patents

Abstract

PURPOSE:To flatten a pipe end part in the prescribed shape simply with less processes by pressing in order the set length of a pipe end part with the outer diameter restricting upper and lower dies having a center folding projection and the upper and lower dies flattening smoothly the rotary direction at right angles of its pipe axis. CONSTITUTION:A center folding press work is performed on the end part of a pipe 2 with the upper and lower dies 6 restricting the outer diameter of the pipe 2 having the prescribed depth and the projection 8 for center folding. The end part of the pipe 2 is then flattened with pressing by the upper and lower dies 7 flattening smoothly from the circle having the same depth by rotating the pipe axial direction at right angles. The thickness of flattened part at the pipe end part becomes about four times of wall thickness of the pipe and is made tough. Also the pipe end part is flattened in the prescribed dimensional shape efficiently with simple less processes.

Description

[Detailed Description of the Invention] [Industrial Application Field] This invention is applicable to diagonal members of catalyst bank grids, diagonal members of steel pipe structures, etc., in which pipe ends are flattened and connected to other members. This invention relates to a processing method for flattening a tube end, and a mold used for the processing.

[Prior art and problems] For example, steel pipes are used for the places (diagonals) of the catalyst puncture grid in a denitrification equipment as shown in Fig. 8, and the steel plate that is the frame material of the grid is connected to the steel pipe that is the place. Conventionally, as a means for this, a gusset plate l as shown in FIG. 4 is fitted into the tube end of the place, welded, and welded and connected to the frame material via the gusset plate.

As shown in FIG. 6, the manufacturing process for the place created in this manner requires 4 steps for the tube, 3 steps for the gusset plate, and 3 steps for joining the tube and gusset plate, for a total of 10 steps. In order to simplify this, it would be possible to use a manufacturing method that simply flattens the tube end, but in that case,
The width of the flattened part becomes larger than the pipe diameter (approximately π/2), causing defects in the shape and structure of the product.

[Object of the Invention] Therefore, the object of the present invention is to provide a processing method for flattening the tube end without increasing the width in a simple process, and
The goal is to create the molds used for the processing.

[Structure of the Invention] In order to achieve this object, the present invention (11) performs a center bending process by axially symmetrically opposing the set lengths of the pipe ends, and then performs a center bending process perpendicular to the direction of the center bending process. A tube end flattening method for flattening a tube end by crushing it from an axially symmetrical direction, and (2) a mold used for flattening the tube end, which is a center-folding die that is symmetrical to the mating surface. It consists of a lower mold and an upper mold each having a mold shape and a flat mold shape, and a strike bar attached to the back side of the lower mold, and the center-folding mold matches the outer diameter of the pipe to be processed. The central bottom of the semi-cylindrical groove has a half-folded protrusion having a predetermined length from the back end in the axial direction, and the front part of the flat mold has the semi-cylindrical groove shape and is set from the back end. The length portion was formed into a flat box groove shape, and the flat box groove shape and the semi-cylindrical groove shape were configured as a mold with a curved surface shape that smoothly connected.

[Operation] When the tube end is flattened using the mold configured as described above, first, the tube end is subjected to two axially symmetrical center-folds. In the center-folding process, the tube wall portion press-fitted inside is folded inward and processed into a flat shape in the next crushing and flattening process. Therefore, the thickness of the flat part thus formed is approximately four times the wall thickness of the tube, but the tube end can be flattened so that the width of the flat part is the diameter of the tube. .

[Example] The present invention will be described below with reference to the illustrated embodiments.

First, the mold used in this tube end flattening method will be explained. FIG. 1(a) shows the upper mold 3, and FIG. 1(b) shows the lower mold 4 and the stopper 5. The half mold 3 and the lower mold 4 have symmetrical shapes with respect to their dividing planes (fitting planes). The stopper 5 only needs to be attached to the lower mold 4.

In this embodiment, a center folding mold 61 is provided on the left side of the drawing, and a flat molding mold 7 is provided on the right side of the drawing, but each mold may be separate.

The center folding mold 6 is formed into a semi-cylindrical concave shape with the same diameter as the outer diameter of the steel pipe 2 to be processed, and has a center bend L) extending in the axial direction at the center of the mold recess on both the upper and lower sides. A protrusion 8 is provided for this purpose. The center-folding protrusion 8 is formed with a smooth curve. In addition, the height and width of the center-folding protrusion 8 should be determined so that, for example, the width of the product after flattening is almost the same as the pipe diameter, the shape of the bamboo after the first step of center-folding is as shown in Figure 2. Therefore, the length of the circular arc (ff) of the unfolded tube is approximately the same length as the diameter of the tube.

The flat mold 7 is on the front side in Fig. 1 (the side without the stopper 5)
The part has a semi-cylindrical concave shape that is the same as the outer diameter of the tube, and the back part is a flattened part.

In this embodiment, the length of the flattened portion is 1. ') is approximately the same length as the length L) of the center-folding protrusion 8. The depth of the flat part shall be twice the wall thickness of the tube, 4 times in total. The shape between the flat part that crushes the center-folded tube and the cylindrical part that holds the tube in its circular shape changes smoothly and connects.
Form it into a spherical surface.

Next, a method for flattening a tube end using this mold will be explained step by step. The steel pipe 2 to be processed is usually heated and subjected to hot bending before processing.

The tip of this tube is inserted straight into the center of the center folding die 6 of the lower die 4, aligning the center of the die with the center of the tube, until it hits the stopper 5, lowering the upper die 3 and pressing. Perform the bending process. Next, this half-folded tube is rotated 90 degrees and inserted straight into the flat mold 7 of the lower mold 4 with the center of the mold and the center of the tube aligned until it hits the stopper 5. When the mold 3 is lowered and pressed, the center-folded part goes inside the crushed and flattened part, and as shown in Fig. 3, the width (i') of the flattened part is can be approximately the same as the diameter of

Note that when it is desired to shorten the flattening length L'), the length can be shortened by placing a liner in front of the stopper 5 and limiting the insertion length of the tube.

FIG. 5 is a perspective view of a tube end flattened by this processing method.

[Effects of the Invention] As explained above, according to the present invention, a gusset plate is not required as a component, and the processing steps include cutting, heating, middle bending, flattening, and care, as shown in FIG. There are 5 steps. This is compared to the conventional 10 shown in Figure 6.
Compared to the process, this will result in significant streamlining.

In addition, conventionally, the cutting length of the pipe had to be determined by considering the protrusion length of the gusset plate, but according to this invention, the length of the pipe can be made the same as the length of the place. It's definitely easy.

According to this invention, the width of the tube end flat portion can be made equal to or less than the tube diameter, and the thickness of the tube end flat portion is approximately four times the wall thickness of the tube, so it is durable.

[Brief explanation of drawings]

Figure 1(a) is a perspective view of the upper mold, Figure 1(b) is a perspective view of the lower mold, Figure 2 is a sectional view of the center-folding part, and Figure 3 is a sectional view of the flattening part. , FIG. 4 is a perspective view of the conventional example, FIG. 5 is a perspective view of the tube after processing according to the present invention, FIG. 6 is a process diagram of the conventional example, FIG. 7 is a process diagram of the process according to the present invention, and FIG.
The figure is a perspective view showing a grid place. In the figure, 2 is a pipe (steel pipe), 3 is an upper mold, 4 is a lower mold, 5 is a stopper, 6 is a center-folding mold, 7 is a flat mold, and 8 is a center-folding projection.

Claims (2)

[Claims] (1) The set length of the tube end is axially symmetrically opposed, and then the tube end is flattened by pressing from an axially symmetrical direction that is perpendicular to the center bending direction. A flattening method for pipe ends. (2) The center-folding mold consists of a lower mold and an upper mold having a center-folding mold shape and a flat mold shape symmetrical to the mating surfaces, and a stopper attached to the back side of the lower mold. The central bottom of a semi-cylindrical groove that matches the outer diameter of the pipe to be processed has a half-folded protrusion of a set length from the back end in the axial direction, and the front side of the flat mold has a semi-cylindrical groove. The mold is shaped such that a portion of a set length from the rear end is a flat box groove shape, and the flat box groove shape and the semicylindrical groove shape are curved surfaces that smoothly connect.