JP2007054882A - Method for efficiently manufacturing pipe with high dimensional accuracy - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for efficiently manufacturing a pipe with high dimensional accuracy, which method can efficiently manufacture the pipe with high dimensional accuracy by preventing the generation of buckling and seizure defects by reducing a punching load when manufacturing the pipe with high dimensional accuracy, e.g. excellent wall thickness deviation, etc. by punching process. <P>SOLUTION: In the method, lubricating films are preliminarily formed on the internal and external surfaces of the pipe 1. Then, a plug 3 is inserted into the pipe 1 so as to floatingly support the pipe 1. Then, the pipe 1 is fed into a die 2 by applying a pushing force 5 to the pipe 1 by means of a pipe pushing machine 4 arranged on the inlet side of the die 2 to perform the punching process by means of the die 2. In this case, the ratio of the contact length 6 between the die 2 and the pipe 1 to the outside diameter 7 of the material pipe is set within the range from 0.5 to 1.0. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a method for efficiently producing a pipe that requires high dimensional accuracy such as an automobile drive system component.

  Metal pipes, for example, steel pipes, are generally classified into welded pipes and seamless pipes. Welded pipes are manufactured by rounding the width of the strip and welding by welding both ends of the roughly rounded width, such as ERW steel pipes, while seamless pipes drill holes of material at high temperatures. It manufactures by the method of rolling with a mandrel mill etc. later. In the case of a welded pipe, the bulge of the welded portion is ground after welding to improve the dimensional accuracy of the pipe, but the plate thickness deviation exceeds 3.0%. In the case of a seamless pipe, it is easy to be eccentric in the drilling process, and a large thickness deviation is likely to occur due to the approximate eccentricity. Although efforts have been made to reduce this thickness deviation in a later process, it cannot be sufficiently reduced, and remains at 8.0% or more at the product stage.

  The pipes of automobile parts and the like are required to have a high dimensional accuracy of 3.0% or less, more strictly 1.0% or less, as deviations in thickness, inner diameter, and outer diameter. As a means for increasing the accuracy of the thickness, inner diameter, and outer diameter of a metal tube, a die and a plug are generally formed after forming a metal tube (both a welded tube and a seamless tube) as generally described in Patent Document 1, for example. A manufacturing method (so-called cold check method) in which a pipe is pulled out cold using a so-called is used.

  However, in the conventional cold check method, when the restrictions on equipment and the thickness and diameter of the tube are large and sufficient pulling stress cannot be obtained and the diameter reduction rate must be lowered, etc., a machining tool (plug and plug) Because the stress of the tube within the gap between the inner surface of the die hole is a tensile force, the contact between the die and the tube, and the drawing plug and the tube is insufficient, and the inner surface and outer surface of the tube are not smoothed, resulting in unevenness. It tends to remain. For this reason, the diameter reduction rate of the pipe is increased by a cold check to improve the contact between the inner and outer surfaces of the pipe, the plug, and the die within the machining tool. However, when the tube is cooled using a die, unevenness is generated on the inner surface of the tube, and the roughness due to the unevenness increases as the diameter reduction ratio of the tube increases. As a result, it has been difficult to obtain a tube with high dimensional accuracy by the cold check method, and a tube with better dimensional accuracy has been strongly demanded.

  As described above, conventionally, when a pipe is pulled out using a die and a plug, it is difficult to improve the dimensional accuracy of the pipe. This comes from insufficient contact of the inner surface of the tube. That is, as shown in FIG. 3, when the plug 3 is inserted and the pipe 1 is pulled out from the die 2, a tensile force is applied to the working bite due to the drawing stress 9 applied by the pipe drawing machine 8 on the exit side of the die 2. appear. Accordingly, since the inner surface of the tube 1 is deformed along the plug 3 on the processing bite entry side, the outer surface of the tube 1 is not in contact with or only slightly contacted. Since the outer surface of the tube 1 is deformed by contacting the die 2, the inner surface of the tube 1 is not contacted or only slightly contacted. For this reason, both the inner and outer surfaces of the tube 1 have free deformation portions in the machining bite, and the unevenness cannot be sufficiently smoothed, and only a tube with low accuracy is obtained after drawing.

  On the other hand, in order to obtain a high-dimension system pipe with good outer diameter deviation, inner diameter deviation, and circumferential thickness deviation, the inventors have disclosed a pipe with a plug inserted in the pipe in Patent Document 2. Has proposed a method of manufacturing a high dimensional accuracy tube in which a die is pushed into a hole of a die and passed through.

In the case of punching, as shown in FIG. 2, by inserting the plug 3 and pushing the tube 1 into the die 2, a cutting tool 5 is applied by the punching force 5 applied by the tube pushing machine 4 on the entry side of the die 2. Compressive stress acts on the interior of all. As a result, the tube 1 can sufficiently come into contact with the plug 3 and the die 2 regardless of whether the processing tool enters or exits. In addition, even within a small diameter reduction ratio, the inside of the working bite becomes compressive stress, so that the tube 1 and the plug 3 and the tube 1 and the die 2 are more easily contacted than the drawing, and the tube 1 is smoothed. It becomes easy to obtain a tube with high dimensional accuracy.
Japanese Patent Application Laid-Open No. 07-032030 JP 2004-314083 A

  However, in the manufacture of high-dimensional accuracy pipes by punching, unlike the drawing process, the processing tool is a compression field, so the surface pressure between the die and the pipe, the plug and the pipe tends to increase, and the plug surface If the frictional force between the inner surface of the tube, the die surface and the outer surface of the tube is not reduced as much as possible, the tube will buckle during processing and seizure will occur on the surface of the tube, resulting in deterioration of the surface quality of the tube after processing. However, not only does the tube not become a product, but the load during processing increases significantly, and processing itself may be impossible. In that case, in order to change the processing conditions, it is necessary to temporarily stop in the middle of processing, extract the tube, replace the die, and extract the plug. As a result, the production efficiency of the pipe is significantly reduced.

  The present invention has been made in view of the above circumstances, and when producing a high-precision tube having a good thickness such as a thickness deviation by punching, the punching load is reduced, and An object of the present invention is to provide a high-efficiency manufacturing method of a high-dimensional accuracy tube that can prevent the occurrence and can manufacture a high-dimensional accuracy tube with high efficiency.

  The present inventors paid attention to the die shape as a means for reducing the punching load. In other words, various die shapes can be applied to process a tube of a predetermined size from the same blank when punching the tube. Therefore, when diligently examining the shape of the die that can reduce the load most, the load decreases as the diameter of the pipe increases due to the influence of the diameter of the pipe, and the influence of the contact length between the die and the pipe also affects. Thus, it was understood that the load decreases as the contact length decreases. As a result, in order to obtain versatility from these relationships and to obtain an appropriate die shape that can reduce the load on various raw pipes, the ratio between the contact length of the die and the pipe and the raw pipe diameter is within a specific range. It was found that it should be limited to. Specifically, it has been found that when the ratio between the contact length of the die and the pipe and the diameter of the raw pipe is in the range of 0.5 to 1.0, the load can be reduced and buckling or seizure in punching can be prevented.

  The present invention has been made based on the above viewpoint and has the following characteristics.

  [1] The contact length between the die and the tube when the tube is fed and punched with a die while a lubricating film is formed on the inner surface and / or outer surface of the tube and the plug is inserted into the tube and floated. A high-efficiency manufacturing method of a high dimensional accuracy pipe, characterized by performing a punching process using a die having a ratio between the outer diameter of the pipe and the outer diameter of the raw pipe.

  [2] The high-efficiency manufacturing method for a high-dimensional accuracy tube according to [1], wherein a drying resin is used as the lubricant.

  [3] The above [1] or [2], wherein a resin, a solution obtained by diluting a resin with a solvent, or an emulsion of a resin is applied to a tube, and a hot air is applied to form a lubricating film on the surface of the tube. ] The high-efficiency manufacturing method of the high dimensional accuracy pipe | tube as described in any one of.

  In the present invention, by performing the punching process using a die in which the ratio of the contact length between the die and the pipe and the outer diameter of the raw tube is within an appropriate range, the punching load is reduced, and buckling or Generation of seizure flaws can be prevented, and a high dimensional accuracy tube can be manufactured with high efficiency.

  An embodiment of the present invention will be described with reference to FIG.

  As shown in FIG. 1, in this embodiment, a lubricant film is formed on the inner and outer surfaces of the tube 1 in advance, and the plug 3 is inserted into the tube 1 to float and is provided on the entry side of the die 2. The tube pusher 4 applies a pushing force 5 to feed the tube 1 and the die 2 performs a punching process.

  At that time, punching is performed using the die 2 in which the ratio between the contact length 6 of the die 2 and the tube 1 and the outer diameter 7 of the raw tube is in the range of 0.5 to 1.0. Yes.

  By doing as described above, in this embodiment, the compressive stress acts on the entire inside of the working bite by the pushing force 5 applied by the pipe pushing machine 4 on the entry side of the die 2. The tube 1 and the die 2 are sufficiently in contact with each other to obtain a tube with good high dimensional accuracy such as thickness deviation, and the ratio of the contact length 6 of the die 2 and the tube 1 to the outer diameter 7 of the raw tube is appropriate. Since punching is performed using a die 2 that falls within the range, the punching load can be reduced, buckling and seizure can be prevented, and high-dimensional accuracy tubes can be manufactured with high efficiency. it can.

  The lubricant used is preferably a dry resin, such as polyethylene wax or polyacrylate, in order to form a strong film of lubricant between the die and the tube and between the plug and the tube. In order to form a lubricating coating on the surface of the tube, it is preferable to apply hot air to the tube by applying a resin, a solution obtained by diluting the resin with a solvent, or an emulsion of the resin to the tube.

  Hereinafter, a description will be given based on examples.

  As an example, a steel pipe with a diameter of 34 mm x 7 mm t x 6 mL is used as a base pipe, and the plug is floated and inserted into the steel pipe using a mirror surface plug and an integrated fixed die, and the steel pipe is inserted at a reduction ratio of 11.8%. By pushing from the side, the diameter of the tube on the die exit side was set to 30 mm, and the tube thickness was set to 7 mmt on the inlet side. At this time, by changing the angle of the die, the contact length between the die and the tube was changed, and 10 pieces were punched or drawn under each condition.

  As Example 1 of the present invention, in the above punching process, the ratio of the contact length between the die and the pipe and the outer diameter of the raw pipe is set to 0.5, and in order to form a lubricating film in advance, a polyethylene wax resin emulsion is used for the inner and outer faces of the pipe. 10 pieces were processed continuously by applying hot air and applying a drying resin film.

  As Example 2 of the present invention, in the above punching process, the ratio of the contact length between the die and the tube and the outer diameter of the raw tube is set to 0.9, and a resin diluted with a solvent is used to form a lubricating coating in advance. The coating was applied to the substrate, hot air was applied, and a drying resin film made of polyacrylate was adhered, and 10 pieces were processed continuously.

  As Comparative Example 1, in the above punching process, a resin emulsion of polyethylene wax was applied to the inner and outer surfaces of the pipe in order to form a lubricating film with a ratio of the contact length between the die and the pipe to the outer diameter of the raw pipe of 0.4. Then, hot air was applied to attach a drying resin film, and 10 pieces were processed continuously.

  As Comparative Example 2, in the above-described punching process, the ratio of the contact length between the die and the tube and the outer diameter of the raw tube was 1.1, and in order to form a lubricating coating, a polyethylene wax resin emulsion was applied to the inner and outer surfaces of the tube. Then, hot air was applied to attach a drying resin film, and 10 pieces were processed continuously.

  As a conventional example, in the drawing process, a ratio of the contact length between the die and the pipe and the outer diameter of the raw pipe is set to 0.5, and in order to form a lubricating coating, a polyethylene wax resin emulsion is applied to the pipe, 10 were continuously processed by attaching a drying resin film.

  Table 1 shows the results of the load at the time of manufacturing these steel pipes, the state of occurrence of surface flaws in the manufactured steel pipe, the presence or absence of buckling, and the machining efficiency. The processing efficiency is shown as a ratio of the number of processing per hour, where the number of processing per hour of the conventional example is 1 (reference).

  As shown in Table 1, in the punching process shown in Comparative Example 1 and Comparative Example 2, the load is large and flaws are generated on the surface of the steel pipe after processing, and the die and plug must be replaced. In Comparative Example 2, the raw tube was buckled, and it was necessary to redo the processing, which significantly reduced the processing efficiency.

  In the case of the drawing shown in the conventional example, the load is low, but the steel pipe has to be processed in a single shot, so the processing efficiency is significantly reduced.

  Compared with these, in the case of the present invention example 1 and the present invention example 2, the load was low, no seizure flaws were generated, and the surface was good and the processing efficiency was remarkably good.

It is explanatory drawing of one Embodiment (Punching process with the die | dye which makes the ratio of the contact length of a die | dye and a pipe | tube, and a raw pipe diameter) the range of 0.5-1.0. It is a figure which shows the comparison technique (Punching process by the die | dye which makes the ratio of the contact length of a die | dye and a pipe | tube and a raw pipe diameter the range exceeding 1.0). It is a figure which shows the method of performing a prior art (drawing process).

Explanation of symbols

1 Pipe 2 Die 3 Plug 4 Pipe pusher 5 Pushing force 6 Contact length between die and pipe 7 Diameter of raw pipe 8 Pipe pulling machine 9 Pulling force

Claims (3)

  When forming a lubrication film on the inner surface and / or outer surface of the tube and inserting the plug into the tube and floating it, the tube is fed and punched with a die. A high-efficiency manufacturing method of a high-dimensional accuracy pipe, characterized by performing a punching process using a die whose ratio to the outer diameter is in the range of 0.5 to 1.0.   2. The high-efficiency manufacturing method for high-dimensional accuracy tubes according to claim 1, wherein a drying resin is used as the lubricant. The high dimension according to claim 1 or 2, wherein a resin, a solution obtained by diluting a resin with a solvent, or an emulsion of a resin is applied to a tube, and hot air is applied to form a lubricating film on the surface of the tube. High-efficiency manufacturing method for precision tubes.

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