JPH0323022A - Pipe member forming method, damper shaft and its manufacture - Google Patents

Abstract

PURPOSE:To improve the working efficiency and yield by executing drawing and crushing to one part, at least, after the weld of electric seam welded pipe is subjected to annealing heat treatment and coat lubricating treatment. CONSTITUTION:The weld zone (electric seam weld zone) 2 formed at the side surface of the pipe member 1 of seam welded pipe is subjected to heat treatment for annealing. The coating 3 lubricating treatment is executed to lubricate the surface. After then one part (top end part) 4 of the pipe member 1 is, at least, subjected to press forming composed of drawing and crushing. The damper shaft of the seam welded pipe is formed. In such a way, the automation for press forming is realized.

Description

[Detailed description of the invention]

[Industrial Application Field] The present application relates to a method for forming a pipe member, a shaft for a damper used in vehicles such as automobiles obtained by this method, and a method for manufacturing the same. [Prior Art] An example of such a damper is a damper used in a connecting portion of a trailing arm. This device consists of an outer cylinder, a pipe-shaped shaft passed through the outer cylinder, and damper rubber filled between the outer cylinder and the shaft.Both ends of the shaft extend from the outer cylinder, and the vehicle body and tray are connected to each other. Some have ring arms connected to each other. It is also known that the connecting portions at both ends of the shaft are made flat by press molding, and the width of the flat connecting portions is made approximately the same as the outer diameter of the pipe portion of the shaft.

[Problems to be Solved by the Invention] As described above, if the width of the flat connecting portions at both ends of the shaft is made to be approximately the same as the outer diameter of the pipe portion of the shaft, the flat portions will not protrude beyond the outer diameter of the pipe. Filling the damper rubber with the shaft inside the outer cylinder becomes much easier, improving work efficiency and reducing product costs. However, in order to form such a flat part, it is necessary to reduce the diameter by drawing and squeezing both ends of the pipe member, and then crushing it. For this reason, the pipe portion of the shaft tends to break during the drawing and crushing process, which normally makes it impossible to form or significantly reduces forming efficiency and yield. In particular, when a low-cost electrical resistance welded pipe is used as a pipe member, the hardness of the electrical resistance welded part due to welding is already higher than that of the other end, and this becomes an obstacle during the above-mentioned processing. Moreover, during the crushing process, it is necessary to set the pipe member into the mold by pressing the electric resistance welded portion with the mold surface. As a result, setting work is done manually, making it difficult to automate the entire process. Therefore, the present application is
The object of the present invention is to provide a pipe member that can solve these problems, a damper shaft using this method, and a method for manufacturing the same. [Means for Solving the Problems] In order to solve the above problems, the method of forming a pipe member in the present application includes heat treatment for annealing the welded part on the side surface of the pipe member made of an ERW pipe, and lubrication of the surface. After the film lubrication treatment is performed, at least a portion thereof is subjected to press forming such as draw processing and crushing processing. Further, the damper shaft according to the present application is a pipe member for forming a damper integrally with an outer cylinder and an elastic body filled inside the outer cylinder, and the end portion extending from the outer cylinder is press-formed. In the case where the connecting part is flat and the width of the connecting part is approximately the same as the outside diameter of the pipe part,
It is characterized by consisting of an electric resistance welded tube with a film formed by film lubrication treatment on its surface. Furthermore, the manufacturing method of the damper shaft according to the present application includes heat treatment for annealing the electric resistance welded portion of the electric resistance welded tube and film lubrication treatment for lubricating the surface, and then drawing the end portion by draw processing. A feature is that this constricted part is crushed to form a flat connecting part, and the width of this flat connecting part is made to be approximately the same as the outer diameter of the pipe part of the shaft.
[Function of the Invention] According to the method for forming a pipe member in the present application, when performing draw processing and press processing, the electric resistance welded portion is annealed in advance and a lubricating film is formed on the surface. This makes the pipe part less likely to crack. Also, when applying the brace, it does not matter where the electric resistance stitch is located. Furthermore, according to the method for manufacturing a damper shaft according to the present application, the above-described method is applied to the end of the pipe member to form a flat connecting portion, so that the width of the connecting portion is set to be approximately the same as the outer diameter of the pipe portion. It becomes possible to press-form it so that it becomes . At this time, molding defects of the pipe member due to the press or shape are reduced. [Example] Figures 1 to 7 show the processing steps. Figures 1 and 2 show a cross section of a steel pipe member l that is a raw material for processing.
An electric resistance stitching portion 2 is formed on this side surface. The chemical composition of this pipe member 1 is appropriately determined so that it has mechanical properties as shown in Table 1 below, for example. (Table 1) Note: D is the pipe diameter, H is the height of the flat part. This pipe member 1 is first subjected to heat treatment (first step) and barker treatment (second step). After that, draw processing (3rd process), press processing (4th process), piercing/cutting process (5th process), and finishing process (6th process).
Follow this order to get the product. The first step is a step aimed at annealing the pipe member 1, and is performed in a continuous annealing furnace in a reducing atmosphere at an appropriate temperature and time, and the mechanical properties of the heat-treated product are as follows. Make sure that it is within the range shown in Table 2. (Table 2) The second step is to form a phosphate film on the surface of the pipe member 1 heat-treated in the first step to lubricate the surface. After immersion for a suitable period of time to form a film, the surface is lubricated with steering soda. Through this step, as shown in FIG. 3, a lubricating film 3 is formed on the surface of the pipe member 1 (the film 3 is not shown in each figure after FIG. 4). The third step is a step in which both ends 4 of the pipe member 1 are reduced in diameter by one or more draw processes, as shown in FIG. In this example, the diameter of the pipe member 1 is 30 mm, and both ends 4 are drawn by drawing twice.
The diameter of the tube was reduced to 21 mm, or 70% of the tube diameter. At this time, the draw processing is performed smoothly due to the processing in the first step and the second step. The fourth step is a step for flattening both end portions 4. First, as shown in FIG. 5, both end portions 4 are made substantially flat by the first press molding. However, at this stage, the flattened parts do not stick together and maintain a slight gap. Subsequently, this part is press-formed again, and as shown in FIG. 6, the upper and lower opposing surfaces are brought into contact with each other, and the mating portions 5 are brought into close contact so that no space is formed. At this time, the width W of both ends 4
- is approximately equal to the pipe diameter D, and is designed not to protrude beyond the outer diameter of the pipe member l. In the fifth step, a seventh
This is the process of piercing the attachment 66 shown in the figure and cutting the tip to a predetermined shape and size. Figure 7 shows the finished product after the 6th process, in which the product in the 5th process was finished by deburring, and the shaft 7 of the damper for the trailing arm is obtained. At this time, both end portions 4 form flat connecting portions of the shaft 7. FIG. 8 shows a damper for a trailing arm using this shaft 7. The shaft 7 is passed through an outer cylinder 8, and the flat connecting part consisting of both ends 4 is connected to the outside of the outer cylinder 8. A damper rubber 9 is filled between the shaft 7 and the outer cylinder 8, and the two are integrated. When manufacturing such a damper, the shaft 7 is
ii] Since the width W of the casing 4 is made almost the same as the diameter D of the pipe member 1 (Fig. 6), it is easy to fill the damper rubber 9 with the shaft 7 inserted into the outer cylinder 8. This has made it possible to make damper manufacturing extremely efficient. Furthermore, since the mating portion 5 is brought into close contact, water is less likely to enter this portion, increasing durability. In addition, the reference numeral 1O in the figure is a protrusion to prevent loosening, and 11 is a trailing arm. Effects of the Invention According to the invention as claimed in claim 1, even if at least a part of the pipe member is press-formed by drawing and crushing, the pipe part is less likely to break during the processing. As a result, work efficiency and yield can be significantly improved. Moreover, there is no need to position and set the electric resistance stitching part during press processing, so automation is possible.
This makes it even more suitable for mass production. Further, according to the inventions of claims 2 and 3, the pipe member forming method described above is used when drawing and crushing is performed by press forming in order to form a flat connecting portion at the end of a shaft made of a pipe member. By doing this, the width of the connecting part is approximately the same as the pipe diameter of the middle pipe part.
Since it can be molded with a high yield, it is possible to obtain a shaft suitable for a damper.

[Brief explanation of the drawing]

1 to 7 are diagrams showing the shaft forming process, in which FIG. 1 is a perspective view of the raw material pipe member, FIG. 2 is an enlarged cross-sectional view thereof, and FIG. 3 is a cross-sectional view after surface treatment. Fig. 4 is a plan view after draw processing, Figs. 5 and 6 are side views during press processing, and Fig. 7 is a plan view after finishing. 8th
The figure is a perspective view of a damper using this shaft. (Explanation of symbols) 1... Pipe member, 2... Electric resistance stitching part, 3... Film,
4... Both ends (connection part), 7... Shaft, 8...
・Outer cylinder, 9...damper rubber, etc. Figure 1 Figure 2 Figure 5 Figure 6 Figure 7 Figure 8

Claims (3)

[Claims] (1) After performing heat treatment to annealing the welded part formed on the side surface of the pipe member made of ERW pipe and film lubrication treatment to lubricate the surface, at least part of the pipe member is subjected to draw processing and crushing. A method for forming a pipe member, characterized by performing press forming, which includes processing, etc. (2) A pipe member that is integrated with an outer cylinder and an elastic body filled inside the outer cylinder to form a damper, and the end extending from the outer cylinder is press-molded to form a flat connecting part. Also, a damper shaft in which the width of the connecting portion is made approximately the same as the outer diameter of the pipe portion, characterized in that the damper shaft is made of an electric resistance welded tube with a film formed by film lubrication treatment on the surface. (3) heat treatment for annealing the ERW part of the ERW pipe;
After applying a film lubrication treatment to lubricate the surface, the ends are squeezed by a draw process, and this squeezed part is further crushed to form a flat connecting part, and the width of this flat connecting part is adjusted to fit the shaft. A method for manufacturing a shaft for a damper, characterized in that the outer diameter of the shaft is approximately the same as the outer diameter of the pipe portion.