JP2012135784A - Working method of metal round pipe and metal round pipe worked with the method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a working method of a metal round pipe enabling to appropriately flatten a part of an outer surface of a bend part of the metal round pipe without bringing it into a largely recessed shape.SOLUTION: The working method of the metal round pipe is used for flattening a part of the outer surface of the bend part 10 by giving press work to the outer surface of the bent bend part 10 of the metal round pipe 1 with a punch 2. A pressing surface 20 formed in the front end of the punch 2 includes a pair of inclined surface parts 20a inclined so that the central part side is recessed relative to the both end sides of the pressing surface 20. In giving the press work to the outer surface of the bend part 10, the both of the pair of the inclined surface parts 20a are brought into face-to-face contact with the outer surface of the bend part 10.

Description

  The present invention relates to a method for flattening a part of a bent portion of a metal round pipe that has been subjected to a bending process, and a metal round pipe that is processed by using this method.

  The present applicant has previously proposed that a metal round pipe is bent to form this pipe, for example, in an oval spiral shape, and that this pipe is used as a heat transfer tube of a heat exchanger. (For example, see Patent Document 1). In this case, for example, as shown in FIG. 7A, for the purpose of stably attaching sensors such as the temperature sensor 80 to the bent portion 10 of the metal round pipe (heat transfer tube) 1, There is a case where it is desired to make a part of the flattening processing unit 14 'a plane or a plane close to the plane. Further, as shown in FIG. 4B, in order to avoid interference between the bent portion 10 of the metal round pipe 1 and the other member 81 of the heat exchanger, a planarization processing portion is formed on a part of the bent portion 10. In some cases, 14 'may be formed.

  As a means for forming the flattening processing portion 14 ′, for example, as shown in FIG. 8, a pressing surface 90 at the tip uses a flat punch 9 to press the bent portion 10 of the metal round pipe 1. Can be considered. However, according to such a means, as shown in FIG. 9, the pressed portion 19 is likely to be greatly recessed inside the metal round pipe 1. This is because the outer surface of the bent portion 10 of the metal round pipe 1 is not a cylindrical surface, but the outermost peripheral portion of the bent portion 10 and its vicinity are part of a spherical surface, unlike the straight portion (non-bent portion). This is because the convex curved surface is close to, and when such a portion is pressed into a flat shape, the pressed portion is easily inverted into a concave shape. As described above, if the pressed portion 19 is greatly depressed, this portion is not properly planarized. Further, when the metal round pipe 1 is a heat transfer tube, if the pressed portion 19 is depressed, the flow passage area of the portion becomes narrow, resulting in a problem that the flow passage resistance is considerably increased.

JP 2007-333343 A

  The present invention has been conceived under the circumstances as described above, and is appropriately planarized without making a part of the outer surface of the bent portion of the metal round pipe into a greatly depressed shape. It is an object of the present invention to provide a method for processing a metal round pipe that can be used, and a metal round pipe processed by using this method.

  In order to solve the above problems, the present invention takes the following technical means.

  According to a first aspect of the present invention, there is provided a metal round pipe machining method, wherein the outer surface of a curved bent portion of the metal round pipe is pressed using a punch, and a part of the outer surface of the bent portion is formed. The pressing surface formed at the tip of the punch is a pair of slanted so that the center side is recessed from both ends of the pressing surface. A configuration having an inclined surface portion is provided, and when the outer surface of the bent portion is pressed, both the pair of inclined surface portions are brought into contact with the outer surface of the bent portion.

According to such a configuration, as is apparent from experimental data described later, the outer surface of the bent portion of the metal round pipe is appropriately flattened while preventing the outer surface of the bent portion from being greatly recessed in the pipe. It is possible to plan.
In understanding the present invention, it should be noted that the pair of inclined surface portions of the pressing surface of the punch used in the method of the present invention is a concave shear (shear angle) provided in the punch for punching press. The roles and functions are completely different and should not be confused. In other words, the shear angle of the punch for punching press reduces the degree of contact between the punch and the workpiece, and reduces the punching press load and noise during punching. Is not intended to positively press the workpiece. On the other hand, the pair of inclined surface portions of the punch used in the present invention is a portion for directly contacting the outer surface of the bent portion of the pipe and positively pressing the outer surface, and is a metal round pipe to be pressed. When the outer surface of the bent portion is a convex cubic curved surface close to a part of the spherical surface, it exerts an action of suppressing the amount of press deformation at the top of the cubic curved surface and the vicinity thereof and is pressed by a punch. It helps to prevent the part from being greatly recessed inside the pipe.

  In the present invention, preferably, the pair of inclined surface portions have a configuration in which the depression angles are within a range of 150 to 160 °. According to such a configuration, it is preferable to increase the flatness of the pressed portion of the outer surface of the bent portion while suppressing the outer surface of the bent portion of the metal round pipe from being recessed in the pipe. It is. This point can also be understood from experimental data described later.

  The metal round pipe provided by the second aspect of the present invention is characterized by being processed by using the metal round pipe processing method provided by the first aspect of the present invention. This metal round pipe can be configured as a heat transfer tube of a heat exchanger.

  The metal round pipe having such a configuration has a flattened portion on the outer surface of the curved bent portion without causing a large depression. Since the flatness of the flattened portion is high, a device such as a sensor can be suitably attached to this portion. In addition, since the flattened portion does not become a state of being greatly recessed inside the metal round pipe, the inner width (inner diameter) of the portion is prevented from being narrowed, and the fluid is contained in the metal round pipe. It is also possible to prevent a large flow path resistance from occurring when circulating the gas.

  Other features and advantages of the present invention will become more apparent from the following description of embodiments of the present invention with reference to the accompanying drawings.

(A) is a principal part front view which shows an example of the metal round pipe and punch used in this invention, (b) is II sectional drawing of (a). It is principal part sectional drawing which shows the state which processes a metal round pipe shown in FIG. 1 using a punch. (A) is a principal part front view which shows an example of the metal round pipe in which the planarization process part was formed by the processing method shown in FIG. 2, (b) is III-III sectional drawing of (a). is there. It is principal part sectional drawing which shows the other example of the planarization process part formed in the metal round pipes. It is a principal part front view which shows the other example of this invention. It is a principal part front view which shows the other example of this invention. (A), (b) is a principal part front view which shows the example which planarizes and uses a part of bending part of metal round pipes. It is a principal part front view which shows contrast with this invention. It is principal part sectional drawing which shows contrast with this invention.

  Hereinafter, preferred embodiments of the present invention will be specifically described with reference to the drawings.

  1 to 3 show an example of the present invention. The method for processing a metal round pipe according to the present embodiment targets a metal round pipe 1 as shown in FIG. The metal round pipe 1 is a pipe made of stainless steel or copper that has been subjected to bending processing, and has a bent portion 10 that is entirely or partially U-shaped in front view and curved in a semicircular arc shape. ing.

  The punch 2 used for flattening a part of the outer surface of the bent portion 10 is made of hard metal, and as shown in FIG. 1B, the pressing surface 20 at the tip is a pair of inclined surface portions 20a. It is the structure which has. The pair of inclined surface portions 20a are substantially U-shaped, and are inclined so that the central portion side is recessed from both end portions of the pressing surface 20 (upper and lower end portions in FIG. 1B). Each inclined surface portion 20a is preferably flat, but may be a curved surface close to a flat surface. The depression angle α of the pair of inclined surface portions 20a is, for example, in the range of 150 ° to 160 °.

  In order to planarize a part of the outer surface of the bending portion 10, the punch 2 is used by bringing both of the pair of inclined surface portions 20 a of the punch 2 into contact with the outer surface of the bending portion 10 as shown in FIG. 2. The part of the outer surface of the bending part 10 is crushed. At that time, the metal round pipe 1 is fixed using an appropriate holder (not shown).

  According to the above-described processing method, the planarization processing unit 14 as shown in FIGS. 3A and 3B is formed. The planarization processing unit 14 has a shape in which the surface thereof is substantially planar without causing a depression toward the inside of the bending unit 10. The planarization processing unit 14 is formed for the following reason. That is, the outer surface of the bending portion 10 to be pressed is originally a convex cubic surface close to a part of the spherical surface, but according to the above-described processing method, the top portion of the cubic surface (of the punch 2). Of the facing portion, the pressing amount of the portion protruding most toward the punch 2) and the vicinity thereof are suppressed, and the pressing amount of the other portions is smaller. As a result, the phenomenon that the top of the cubic curved surface and the vicinity thereof are deformed so as to be largely reversed inside the metal round pipe 1 is prevented, and the planarization processing unit 14 having a high flatness is obtained.

  The metal round pipe 1 subjected to the above-described processing is used as a heat transfer tube of a heat exchanger as described in Patent Document 1, for example. The planarization processing unit 14 plays a role similar to that of the planarization processing unit 14 ′ of FIG. 7 described above, and is useful for attaching a device such as a sensor or avoiding interference with other members. . As described above, the planarization processing unit 14 has a high degree of flatness, and thus it is possible to easily and appropriately attach devices such as sensors. In addition, since the planarization processing unit 14 is not greatly recessed inside the metal round pipe 1, it is possible to prevent the inner width of the pipe from being narrowed at the location where the planarization processing unit 14 is formed. Therefore, when the fluid is circulated in the metal round pipe 1, the problem that the planarization processing unit 14 has a large flow path resistance can be appropriately solved.

The inventor of the present invention conducted an experiment in which the punch 2 is subjected to press working on a bent portion of a metal round pipe by using a punch 2 having different angles of depression α of the pair of inclined surface portions 20a. As the metal round pipe to be processed, the following first to third metal round pipes were used.
First metal round pipe: stainless steel (JIS: SUS304L), outer diameter 8 mm, wall thickness 0.3 mm, bending radius 20 mm
Second metal round pipe: copper (JIS: C1220T), outer diameter 18 mm, wall thickness 1.0 mm, bending radius 20 mm
Third metal round pipe: copper (JIS: C1220T), outer diameter 12.7 mm, wall thickness 0.6 mm, bending radius 24 mm
The position where the press working is performed in the bent portion is the same position as in the previous embodiment shown in FIGS.
The results of this experiment are as shown in the following “Table 1”, and similar results were obtained for any of the first to third metal round pipes.

  As understood from the results in Table 1, when the included angle α of the pair of inclined surface portions 20a of the punch 2 is 180 °, the press working is performed in the same manner as described in the background art section (FIG. 9). The part that was made was greatly recessed inside the pipe. On the other hand, when the depression angle α was 150 ° or 160 °, the pressed portion was not recessed inside the pipe, and the surface thereof was almost flat. When the depression angle α was 140 °, as shown in FIG. 4, two small recessed portions 15 were generated in the planarization processing unit 14.

  From the above results, it can be understood that when the depression angle α is in the range of 150 to 160 °, the planarization processing unit 14 has a form close to a flat surface without a depression. The material of the metal round pipe used in the experiment is two types of stainless steel and copper, but even if it is a material other than these, as long as it is a material having the same hardness or property, the same as described above The result is considered to be obtained.

  When the depression angle α is 140 °, a small dent 15 is generated, but this dent 15 is smaller than the dent shown in FIG. Therefore, even when the depression angle α is reduced to about 140 °, the planarization processing unit 14 can be in a better form than when the depression angle α is 180 °. Therefore, in the present invention, the depression angle α can be less than 150 °.

  5 and 6 show another embodiment of the present invention. In these drawings, elements that are the same as or similar to those in the above embodiment are given the same reference numerals as in the above embodiment.

  In the embodiment shown in FIG. 5, the portion to be pressed by the punch 2 is not the most end portion n1 (the right end portion in the figure) of the bent portion 10 of the metal round pipe 1, but a portion shifted from the end portion n1. n2. The outer surface of this part n2 is also a cubic curved surface close to the same spherical surface as the outer surface of the outermost part n1, and the planarization processing unit 14 obtained in the above embodiment can be formed. Among the outer surfaces of the bent portion 10, the outer surface of the region A near the outermost periphery (the region closer to the outer periphery than the center line C and where cross-hatching is inserted) is a cubic curved surface close to a spherical surface. The present invention is optimal when any part of the region A is planarized.

In the embodiment shown in FIG. 6, the bent portion 10 of the metal round pipe 1 has a so-called ¼ arc shape. Even if it is the bending part 10 of such a form, it is possible to apply this invention and to form the planarization process part whose surface is near a plane appropriately. Of course, the present invention can be applied to a bent portion other than a semicircular arc shape or a quarter arc shape.

  The present invention is not limited to the contents of the above-described embodiment. The specific steps of the metal round pipe processing method according to the present invention can be changed within the intended scope of the present invention. The specific configuration of each part of the metal round pipe according to the present invention can be changed in design.

  The metal round pipe to which the present invention is applied is suitable for use as a heat exchanger tube of a heat exchanger, but can also be used for other purposes.

1 Metal round pipe 2 Punch 10 Bending part (of metal round pipe)
14 Planarization processing part 20 Press surface (for punch)
20a Inclined surface (pressing surface)

Claims (4)

The outer surface of the curved bent portion of the metal round pipe is subjected to press processing using a punch, and is a processing method of the metal round pipe for planarizing a part of the outer surface of the bent portion,
The pressing surface formed at the tip of the punch has a configuration having a pair of inclined surface portions that are inclined so that the center side is recessed from both ends of the pressing surface,
When pressing the outer surface of the bent part, both of the pair of inclined surface parts are brought into face-contact with the outer surface of the bent part.   2. The method for processing a metal round pipe according to claim 1, wherein a depression angle of the pair of inclined surface portions is in a range of 150 to 160 °.   A metal round pipe, which is processed using the metal round pipe processing method according to claim 1.   The metal round pipe of Claim 3 comprised as a heat exchanger tube of a heat exchanger.

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