JP2007090392A - Highly-efficient and consistent manufacturing method of high dimensional precision pipe - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a highly-efficient and consistent manufacturing method of a high dimensional precision pipe capable of consistently manufacturing the high dimensional precision pipe with high efficiency by reducing the punching load and preventing occurrence of buckling and seizure flaw or the like when manufacturing the high dimensional precision pipe excellent in wall thickness deviation or the like by punching. <P>SOLUTION: A corner 6 of an approach part of a die 2 and a bearing has a round shape. The radius Rd of curvature of the round shape is set to be ≥5 mm. A corner 7 of an approach part of a plug 3 and the bearing has also a round shape. The radius Rp of curvature is set to be ≥5 mm to perform the punching. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a method for stably and 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, 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 the fact that the contact becomes insufficient. That is, as shown in FIG. 3, when the plug 3 is inserted and the pipe 1 is pulled out from the die 2, the pulling force 9 applied by the pipe puller 8 on the exit side of the die 3 causes a tension in the machining tool. 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 pipe 1 into the die 2, the punching force 5 applied by the pipe pushing machine 4 on the entry side of the die 2 is used to All the inside is subjected to compressive stress. 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 and stable manufacturing method of a high-dimensional accuracy tube that can prevent the occurrence and stably manufacture a high-dimensional accuracy tube.

  The present inventors paid attention to the die shape and the plug shape as a means for reducing the punching load when manufacturing a high-dimensional accuracy tube by punching.

  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 die shape that can reduce the punching load the most, the stress acting on the tube was the largest between the die approach and the bearing (corner), and it was found that stress concentration occurred. . As a result, it has been found that not only plastic deformation of the tube does not proceed smoothly, but also that the lubricant is not sufficiently supplied, and the load during processing increases and buckling and seizure are likely to occur. In other words, if the tube is smoothly plastically deformed at the corner between the approach portion and the bearing, the load during processing can be reduced, and buckling and seizure can be prevented. It has been found that a round shape may be used. Further, it has been found that the plug shape is more preferable if the corners of the approach portion and the bearing are made to have an appropriate round shape as in the case of the die shape.

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

  [1] When a pipe is inserted and floated while a lubricating film is formed on the inner surface and / or outer surface of the tube and a plug is inserted into the tube and floated, the die approach and bearing A high-efficiency, stable production method for high-dimensional accuracy tubes, characterized in that a round shape is formed between the two and the curvature radius of the round shape is 5 mm or more.

  [2] The high-efficiency and stable production method for a high-dimensional accuracy tube according to [1], wherein a round shape is formed between the approach portion of the plug and the bearing, and the radius of curvature of the round shape is 5 mm or more.

  [3] The highly efficient and stable production method for a high dimensional accuracy tube according to the above [1] or [2], wherein a dry resin film is used as the lubricating film.

  [4] The above [1] to [3], 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. ] The highly efficient stable manufacturing method of the high dimensional accuracy pipe | tube in any one of.

  In the present invention, since the punching process is performed using a die having an appropriate round shape between the approach portion and the bearing, the stress concentration between the approach portion and the bearing is reduced, The tube is smoothly plastically deformed, the punching load is reduced, the occurrence of buckling and seizure flaws is prevented, and a high dimensional accuracy tube can be stably 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, the corner 6 between the approach portion of the die 2 and the bearing is rounded, the radius of curvature Rd of the round shape is set to 5 mm or more, and the corner 7 between the approach portion of the plug 3 and the bearing is also rounded. And the radius of curvature Rp of the round shape is 5 mm or more.

  By the way, as for the shape of the corner 6 of the approach portion of the die 2 and the bearing, when considering an appropriate shape that can sufficiently reduce the punching load with respect to various raw pipes, a round shape having a curvature radius Rd of 5 mm or more is considered. If there is, it has been found that the stress concentration at the corner between the approach portion and the bearing can be reduced, the tube 1 can be smoothly plastically deformed, and the punching load can be sufficiently reduced.

  Further, as to the shape of the corner 7 of the approach portion of the plug 3 and the bearing, an appropriate shape capable of reducing the punching load with respect to various raw pipes has been studied, and if it is a round shape having a curvature radius Rp of 5 mm or more. For example, it has been found that the stress concentration at the corner between the approach portion and the bearing can be reduced, and the tube 1 can be plastically deformed more smoothly to further reduce the punching load.

  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 in sufficient contact with each other to obtain a tube with good high dimensional accuracy such as a thickness deviation, and the corner 6 of the approach portion and the bearing has an appropriate round shape. Since the corner 7 with the bearing uses a plug having an appropriate round shape, the stress concentration at the corner between the approach portion and the bearing is reduced, and the tube 1 is smoothly plastically deformed. Can be prevented, buckling and seizure can be prevented, and a high dimensional accuracy tube can be stably manufactured with high efficiency.

  The lubricant used is preferably a dry resin, such as polyethylene wax or polyacrylate, in order to form a firm film of the 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, a round shape was formed between the approach portion of the die and the bearing, and the radius of curvature Rd was changed, so that ten pieces were punched or drawn under each condition.

  As Example 1 of the present invention, in the above punching process, a die having a round shape with a radius of curvature Rd of 10 mm between the approach portion and the bearing, and a round shape with a radius of curvature Rp of 3 mm between the approach portion and the bearing. In order to form a lubricating coating in advance, a polyethylene wax resin emulsion was applied to the inner and outer surfaces of the tube, hot air was applied to attach a drying resin coating, and 10 were continuously processed.

  As Example 2 of the present invention, in the above punching process, a die having a round shape with a curvature radius Rd of 30 mm between the approach portion and the bearing, and a round shape with a curvature radius Rp of 30 mm between the approach portion and the bearing. In order to form a lubricating film in advance, a resin diluted with a solvent is applied to the inner and outer surfaces of the pipe, hot air is applied, and a dry resin film made of polyacrylate is adhered to the plugs. processed.

  As a comparative example, in the above punching process, a die and a plug having a slightly round shape between the approach portion and the bearing, that is, a round shape having a curvature radius Rd, Rp of 3 mm between the approach portion and the bearing. In order to form a lubricating film in advance using the die and the plug, a polyethylene wax resin emulsion was applied to the inner and outer surfaces of the pipe, hot air was applied to attach the drying resin film, and 10 pieces were continuously processed.

  As a conventional example, in the drawing process, a polyethylene wax resin emulsion is used as a tube in order to form a lubricating film in advance by using a round die with a radius of curvature Rd and Rp of 3 mm between the approach portion and the bearing. It was coated and applied with hot air to attach a drying resin film, and 10 were processed continuously.

  Table 1 shows the results of the load, the presence or absence of occurrence of buckling, and the machining efficiency in the production of these steel pipes. 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).

  From Table 1, in the punching process shown in the comparative example, the load was large and buckling occurred. 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 Invention Example 1 and Invention Example 2, the load was low, buckling did not occur, and the processing efficiency was remarkably good.

The figure which showed one Embodiment (The punching process is carried out with a die | dye by making a round shape of a predetermined dimension between the approach part of a die | dye and a bearing). The figure which showed the comparison technique (The punching process is performed by using a die with a slightly round shape between the approach portion of the die and the bearing). The figure which showed the prior art (performing drawing).

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Pipe 2 Dies 3 Plug 4 Pipe pushing machine 5 Pipe pushing force 6 Round shape part between die approach part and bearing 7 Round shape part between plug approach part and bearing 8 Pipe drawing machine 9 Pipe drawing Power

Claims (4)

  A lubrication film is formed on the inner surface and / or outer surface of the tube, and a plug is inserted into the tube and floated. When the tube is fed and punched with a die, it is between the die approach and the bearing. Is a round shape, and the curvature radius of the round shape is 5 mm or more.   2. A highly efficient and stable manufacturing method for a high dimensional accuracy tube according to claim 1, wherein a round shape is formed between the approach portion of the plug and the bearing, and the radius of curvature of the round shape is 5 mm or more.   3. A highly efficient and stable method for producing a high dimensional accuracy tube according to claim 1, wherein a dry resin film is used as the lubricating film.   4. 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. A high-efficiency stable manufacturing method for high-dimensional accuracy tubes as described in 1.

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