JP4914962B2 - Pipe manufacturing method - Google Patents

Description

  The present invention relates to a pipe and a pipe manufacturing method.

  Various pipe processing methods for manufacturing a pipe so as to connect the first straight portion and the second straight portion by a bent portion have been proposed.

  Patent Document 1 discloses a pipe processing method for bending a pipe used in a heat exchanger or the like. In this pipe processing method, first, the vicinity of the pipe end of a long pipe is bent with a normal large bending radius, and then the end surface of the pipe end is compressed from the pipe end direction by a punch, which is a pressing member, so that a small radius is obtained. After that, bulge processing of the pipe end is performed.

Patent Document 2 discloses a method of forming a pipe used for piping arranged in a heat exchanger or the like. In this pipe forming method, a pipe having a predetermined length is bent into a U shape by a bending apparatus, the U-shaped pipe is inserted into a restraining jig having a concave forming groove, and both ends of the U-shaped pipe are connected to each other. Restraint and insert the cored bar into the pipe while pressing both ends of the tube toward the restraining jig to form a C-shaped pipe.
JP-A-9-1247 JP 2004-216388 A

  However, such a conventional method cannot completely avoid the occurrence of a problem that the pipe is crushed or dented at a small bend.

  In the processing method described in Patent Document 1, in order to perform bending with a small radius, the end face of one pipe end of the pipe is compressed by one punch from the pipe end direction. Thus, when compressing the end face of one pipe end, the inner wall surface of the other pipe end opposite to the other side where the punch does not exist is not supported by the cored bar and is therefore press-molded. There will be no non-press molding surface. As a result, it is unavoidable that the bent part of the molded pipe and the vicinity thereof are crushed and small dents are formed on the inner peripheral side thereof.

  In the processing method described in Patent Document 2, a C-shaped pipe is formed by entering two punches or a cored bar into the pipe while pressing both pipe ends in parallel in the same direction. In this case, the pipe inner wall portion of the large bent portion between the two punches or the cored bar is not supported by the cored bar, and is not pressed and formed as a non-pressed molded surface. Therefore, it is difficult to avoid that the bent portion of the molded pipe and the vicinity thereof are crushed or that a small dent is formed on the inner peripheral side thereof.

  Patent Document 2 discloses a method of causing a spherical rocking body to enter a pipe. In this case, it is possible to keep the inner diameter of the pipe unchanged, but the pipe is limited to a pipe that is connected with a large bent portion, such as a C-shaped pipe, where the first straight portion and the second straight portion are far apart. It is difficult to manufacture a pipe having a small-diameter bend on the inner peripheral side of the inner wall surface of the bent portion.

  An object of the present invention is to provide a pipe in which a small dent is not generated on the inner peripheral side of a bent portion and a method for manufacturing such a pipe.

  Examples of the solving means of the present invention are as follows.

(1) In the pipe (10) in which the first straight part (10b) and the second straight part (10c) are connected by the bent part (10a) ,
The inner wall surface on the inner peripheral side of the first straight portion (10b ) is formed as a first pressing molding surface (10t) at least near the bent portion (10a) ,
The inner wall surface on the inner peripheral side of the second straight part (10c ) is formed as a second pressing molding surface (10m) at least near the bent part (10a) ,
The second press forming surface of the first press forming surface (10t) and the second linear portion of the first linear portion (10b) (10c) (10m ) is connected directly with the inner wall surface inner peripheral side of the bent portion (10a) Or are close to each other ,
Of the first straight part (10b) of the pipe (10), the inner peripheral area near the bent part (10a) has an outer wall surface that is continuously linear from other areas, and has a dent. First, it is straight, and the plate thickness is gradually increasing toward the bent portion (10a).
Of the second straight portion (10c) of the pipe (10), the inner peripheral region near the bent portion (10a) has an outer wall surface that is continuously linear from other regions, and is recessed. First , the pipe is straight and the thickness is gradually increased toward the bent portion (10a) .

( 2 ) In order to manufacture a pipe that connects the first straight portion (10b) and the second straight portion (10c) with the bent portion (10a) , a first press is applied to the inner wall surface of the first straight portion (10b). In a state where the member (12) is inserted and the second pressing member (14) is inserted into the inner wall surface of the second linear portion (10c) , the first pressing member (12) and the second pressing member (14 ) Are brought into contact with each other or close to each other, and the first press molding surface (10t) is at least near the bent portion (10a) by the first pressing member (12) on the inner peripheral wall surface of the first linear portion (10b ). forming a, and forming the inner peripheral side of the inner least bend by the second pressing member in the wall (14) near the second press forming surface of (10a) of the second linear portion (10c) (10 m) pipe A manufacturing method comprising :
First, the second pressing member (14) forms the second pressing surface (10m) up to the bent portion (10a) on the inner peripheral wall surface of the second linear portion (10c), and then the first pressing member. (12) to form the first pressing molding surface (10t) up to the bent portion (10a) on the inner wall surface on the inner peripheral side of the first straight portion (10b) ,
At that time, the first pressing member (12) is advanced with respect to the fixed second pressing member (14), and the entire inner wall surface of the first linear portion (10b) is pressed against the first pressing member (12). The inner peripheral side of the bent portion (10a) is compressed so that the thickness of the bent portion (10a) is gradually increased and the difference in length between the inner side and the outer side of the bent portion is increased. The pipe manufacturing method is characterized in that the first press-molding surface (10t) is formed so as to extend straight at the same time as the area becomes smaller .

  According to the method of the present invention, it is possible to accurately manufacture a pipe that has a small bend on the inner peripheral side of the bent portion and does not have a small dent. The inner peripheral side of the bent part and the nearby part will not be crushed or dented.

  In the pipe of the present invention, the first press molding surface of the first straight portion and the second press molding surface of the second straight portion are connected or close to each other on the inner peripheral side of the inner wall surface of the bent portion. It is easy to manufacture a pipe in which the shape and the thickness of the part and its nearby part are accurately controlled. When manufacturing such a pipe, it is not necessary to apply a compressive force to the pipe end face.

  The first press-molding surface and the second press-molding surface are directly connected on the inner peripheral side of the inner wall surface of the bent portion, or are close to each other, and the outer wall of the first straight portion and the outer wall of the second straight portion However, when the concave portion is straight and close to the inner peripheral side of the bent portion, it is possible to secure a long straight portion of the pipe in a case where the total length of the pipe is limited. In other words, the pipe can be made compact.

  In the present invention, it is preferable to use a punch or a metal core as the pressing member.

  The present invention relates to a method of manufacturing a pipe so that a first straight portion and a second straight portion are connected by a bent portion. The first punch is inserted into the inner wall surface of the first straight portion, and the second punch or the core metal is inserted into the inner wall surface of the second straight portion. In this state, the front end of the first punch and the front end of the second punch or the metal core are brought close to each other, and the first press-molding surface is at least near the bent portion by the first punch on the inner wall surface of the first straight portion. And a second press-molding surface is formed on the inner wall surface of the second straight portion at least near the bent portion by a second punch or a metal core. At that time, the first press-molding surface and the second press-molding surface are made to have a very small diameter on the inner peripheral side of the inner wall surface of the bent portion and are brought close to each other.

  When the first punch and the second punch or the metal core are brought close to each other, preferably, the second punch or the metal core is fixed at a predetermined position, and then the first punch is brought close to the second punch or the metal core.

  When the first punch and the second punch or the metal core are brought close to each other, the punches are preferably brought close to each other at a right angle with respect to the metal core, but may be made close to each other at an angle larger or smaller than the right angle.

  When the outer peripheral side of the inner wall surface of the bent portion is pressed by the first pressing member, and the inner peripheral side of the inner wall surface of the bent portion is pulled inward accordingly, the inner wall surfaces of the first linear portion and the second linear portion are Since the inner peripheral side is supported from the inside by the first pressing member and the second pressing member, the area on the inner peripheral side of the bent portion is gradually reduced, and at the same time, the first pressing molding surface and the second pressing molding surface are little by little. growing. Therefore, the inner peripheral side of the bent part and the vicinity thereof is not crushed or dented.

  In the above-described embodiment, the first punch and the second punch or the metal core are brought close to each other, but they may be brought into contact with each other.

  Furthermore, the present invention relates to a pipe in which a first straight portion and a second straight portion are connected by a bent portion. The inner wall surface of the first straight portion is formed as a first press-molded surface at least near the bent portion, and the inner wall surface of the second straight portion is formed as a second press-formed surface at least near the bent portion. The 1st press molding surface and the 2nd press molding surface are directly connected by the inner peripheral side of the inner wall surface of a bending part, or it adjoins mutually. It is preferable that the inner peripheral side of the inner wall surface of the bent portion has a minimum diameter or, if necessary, substantially zero.

  Moreover, it is preferable that the plate | board thickness of the inner peripheral side of a 1st linear part and the plate | board thickness of the inner peripheral side of a 2nd linear part become thick toward a bending part. When increasing the wall thickness of a pipe, bend the pipes with the same thickness before the start of processing, and use the difference in length between the inner and outer circumferences of the pipe, and in the middle of the manufacturing process, It is preferable to increase the thickness on the inner peripheral side and the vicinity thereof.

  More preferably, the outer wall surface of the first straight portion and the outer wall surface of the second straight portion are straight and indented in all regions including the vicinity of the inner peripheral side of the bent portion.

  The first press-molding surface and the second press-molding surface are usually left in the state immediately after being molded by the pressing action of the pressing member. However, if necessary, various processes are performed after the press molding. May be. The press molding surface as used in the field of this invention contains the state which carried out such a process.

  Embodiments of the present invention will be described below with reference to the drawings. In addition, in order to make a figure legible, the type | mold for a process arrange | positioned corresponding to a punch and a metal core is abbreviate | omitting illustration. For the configuration of these types, for example, the configuration described in Patent Document 1 can be referred to.

  1-3 is explanatory drawing which shows the example of a part of a series of manufacturing processes.

  The punch 12 is a typical example of the pressing member in the present invention, and the cored bar 14 is another typical example of the pressing member in the present invention.

  In the present invention, the pipe 10 has a first straight portion 10b and a second straight portion 10c connected by a bent portion 10a.

  When manufacturing a pipe, it is preferable to prepare a large number of preliminary pipes 10 having a bent portion 10a which is previously bent and formed into a large bent shape.

  The preliminary pipe 10 thus prepared has a first end face 10d at one open end and a second end face 10e at the other open end. The preliminary pipe 10 in the pre-processed state has a generally “<” shape, and the entire inner wall surface from the first end surface 10 d to the second end surface 10 e is the inner wall surface 10 f. The entire outer wall surface from the first end surface 10d to the second end surface 10e is an outer wall surface 10g.

  FIG. 2 shows an enlarged view of the vicinity of the bent portion 10a of the preliminary pipe 10 shown in FIG.

  In FIG. 2, the inner peripheral side portion of the bent portion 10a is shown as the inner peripheral side 10h. The outer peripheral side portion of the bent portion 10a is shown as the outer peripheral side 10i.

  In the pipe manufacturing method of the present invention, first, the punch 12 is inserted into the inner wall surface of the first straight portion 10b of the preliminarily processed preliminary pipe, and the inner wall surface of the second straight portion 10c of the pipe is inserted. Insert the cored bar 14 inside.

  This point will be described in more detail. The pipe 10 is initially in a pre-processed state in which the bent portion 10a is bent with a diameter larger than the diameter indicated by the broken line 10j, and one open end (the first end of the pipe 10) The metal core 14 is inserted from the second end face 10e), the punch 12 is inserted from the other open end (first end face 10d), and the punch 12 is advanced to approach the fixed metal core 14. A line (shape) on the inner peripheral side 10h of the bent portion 10a in the middle of processing is indicated by a broken line 10j, and a line (shape) on the outer peripheral side 10i of the bent portion 10a in the middle of processing is indicated by reference numeral 10k. It is shown by the solid line.

  Next, the punch 12 is further moved closer to the core bar 14, and first, the second pressing molding surface 10m is formed on the inner wall surface of the second linear portion 10c by the core bar 14 to the vicinity of the bent portion 10a. . Subsequently, the first press-molding surface 10t is extended to the vicinity of the bent portion 10a on the inner wall surface 10f of the first straight portion 10b by the punch 12, and is formed as shown in FIG.

  This point will be described in detail. When the metal core 14 is fixed, the punch 12 advances along the central axis Y of the first straight portion 10b by a predetermined distance in the direction of the arrow W (FIG. 1). The line (shape) on the inner peripheral side 10h of the bent portion 10a at this stage is shown by a solid line (FIG. 2) with a reference numeral 10n, and the line (shape) on the outer peripheral side 10i of the bent portion 10a is a solid line with a reference numeral 10p. It is shown. The broken line 10q of FIGS. 1-2 shows the outer wall surface shaping | molding end line of the bending part 10. FIG.

  3 to 4 show a state where the molding process is completed.

  First, in detail with reference to FIG. 3, the outer peripheral side 10 i of the outer wall surface of the bent portion 10 a is pressed to the molding end line 10 q by the punch 12.

  On the inner wall surface of the first straight portion 10b, the first press molding surface 101 is extended by the punch 12 to the vicinity of the inner peripheral side of the bent portion 10a. At this time, the entire inner wall surface of the first straight portion 10 b is pressed against the punch 12. In particular, the boundary portion between the inner wall surface of the first straight portion 10b and the inner peripheral side of the bent portion 10a is pressed against the side surface 12a corresponding to the punch 12, and is straightened, so that the pressing surface is linearly extended. The At this time, the inner peripheral side of the bent portion 10a is compressed, and the plate thickness gradually increases. The difference in length between the inner side and the outer side of the bending is increased, the area on the inner peripheral side of the bent portion 10a is decreased, and at the same time, the first pressing molding surface 10t is formed to extend straight.

  Further, the inner wall surface of the second straight portion 10 c is pressed against the core metal 14. In particular, the inner peripheral side of the inner wall surface of the second straight portion 10c is pressed against the upper surface 14a of the core metal 14 and is straightened, so that the pressing surface is linearly extended. At this time, the inner peripheral side of the bent portion 10a is compressed, and the plate thickness gradually increases. In the form in which the difference between the inner and outer lengths of the bending is increased, the inner peripheral side of the bent portion 10a is reduced, and at the same time, the second pressing molding surface 10m is extended.

  At the time of completion of the press molding, the first press molding surface 10t of the first linear portion 10b and the second press molding surface 10 of the second linear portion 10c are very close to each other on the inner peripheral side of the bent portion 10a. There is almost no non-press molding surface.

  Of the inner wall surface of the second straight portion 10c, the surface 10s located below the core bar 14 is not pressed by the punch 12 and the core bar 14, and is thus configured as a non-press-molded surface. In the illustrated example, such a non-pressed molding surface remains only in a very narrow inner wall surface area in the pipe. However, in the present invention, the non-press-molded surface may be formed in a wider area except for the inner peripheral side of the bent portion 10a.

  FIG. 4 is an explanatory diagram for showing the pressing surface in the present invention in more detail.

  With reference to FIG. 4, the pressing surface and the non-pressing surface 10s will be described in detail.

  The punch 12 is slightly tapered on the inner peripheral side of the region B during processing. In other words, the thickness of the punch 12 is gradually reduced toward the tip 12b. As a result, the A region of the first straight portion 10b of the pipe 10 has an outer wall surface that is a straight surface continuously from other regions, and is straight and not concave. The plate | board thickness of A area | region of the 1st linear part 10b of the pipe 10 is increasing little by little toward the bending part 10a.

The distal end portion 14b of the cored bar 14 is also inclined so as to become gradually smaller toward the distal end surface 14c of the cored bar 14 on the inner peripheral side. As a result, in the C region of the second straight portion 10c of the pipe 10, the outer wall surface is a straight surface continuously from other regions, and is straight and not straight. The plate | board thickness of C area | region of the 2nd linear part 10c of the pipe 10 is increasing little by little toward the bending part 10a. In FIG. 4, the 1st press molding surface 10t of the 1st linear part 10b and the 2nd linear part 10c The distance E from the second pressing molding surface 10m is preferably 1 mm or less (more preferably 0.5 mm or less). The distance E can be substantially zero as required.

  The intersection angle F between the central axis Y of the first straight part 10b and the central axis X of the second straight part 10c is preferably 135 to 90 degrees (more preferably 100 to 90 degrees).

  FIG. 5 is a schematic cross-sectional view showing an example of a pipe manufactured by the pipe manufacturing method of the present invention.

  Table 1 shows many pipes shown in FIG. 5, and any four pipes (samples 1 to 4) are selected from them, and the thickness of the inner circumference side of these pipes (samples 1 to 4) is measured. The results are shown.

In FIG. 5, the measurement locations corresponding to Table 1 are indicated by rounded numbers, the first punch side is indicated by reference symbol P, and the second punch or core metal side is indicated by reference symbol Q.

  As shown in Table 1, it was confirmed that the plate thickness on the inner peripheral side of the first straight portion and the plate thickness on the inner peripheral side of the second straight portion gradually increased toward the bent portion. It was done.

  In addition, it is confirmed that the outer wall surface of the first straight portion and the outer wall surface of the second straight portion are both straight straight surfaces in the entire region including the region near the bent portion on the inner peripheral side. It was done. No crushing or small dent was observed in the bent part on the inner circumference side of all the pipes and in the vicinity.

  It should be noted that the present invention is not limited to the illustrated embodiment described above. The shape and arrangement of the pipes, punches and cores are arbitrary. The shape of the press molding surface and the molding method are not limited to those illustrated. For example, in the example shown in FIGS. 1 to 3, the second press-molding surface 10m is formed before the first press-molding surface 10t is formed. You may form the 2nd press molding surface 10m simultaneously.

It is explanatory drawing which shows a part of example of a series of manufacturing processes in this invention method. FIG. 2 shows an enlarged view of the vicinity of a bent portion of the pipe of FIG. 1. The state which the shaping | molding process of the pipe of FIG. 1 was completed is shown. It is explanatory drawing of the press molding surface in the pipe of this invention. It is a schematic sectional drawing which shows the pipe actually manufactured by the pipe manufacturing method of this invention.

Explanation of symbols

10 pipe 10a bent part 10b first straight part 10c second straight part 10d first end face 10e second end face 10f inner wall face 10g outer wall face 10h inner circumference side 10i outer circumference side 10j, 10n inner circumference line 10k, 10p outer circumference side Line 10m Second press molding surface 10q Molding end line 10s Non-press molding surface 10t First press molding surface 12 Punch (an example of a pressing member)
12a Punch side surface 12b Punch tip 14 Core metal (an example of a pressing member)
14a Top surface 14b of the core metal 14b Tip end portion 14c of the core metal

Claims (1)

In order to manufacture a pipe that connects the first straight portion (10b) and the second straight portion (10c) by the bent portion (10a), a first pressing member (12 is provided in the inner wall surface of the first straight portion (10b). ) And the first pressing member (12) and the second pressing member (14) in a state where the second pressing member (14) is inserted into the inner wall surface of the second linear portion (10c). A first pressing molding surface (10t) is formed at least near the bent portion (10a) by the first pressing member (12) on the inner peripheral wall surface of the first linear portion (10b) in contact with or in proximity to each other. And the pipe manufacturing method which forms the 2nd press molding surface (10m) at least near the bending part (10a) by the 2nd press member (14) on the inner wall surface of the inner peripheral side of the 2nd straight part (10c). There,
First, the second pressing member (14) forms the second pressing surface (10m) up to the bent portion (10a) on the inner peripheral wall surface of the second linear portion (10c), and then the first pressing member. (12) to form the first pressing molding surface (10t) up to the bent portion (10a) on the inner wall surface on the inner peripheral side of the first straight portion (10b),
At that time, the first pressing member (12) is advanced with respect to the fixed second pressing member (14), and the entire inner wall surface of the first linear portion (10b) is pressed against the first pressing member (12). The inner peripheral side of the bent portion (10a) is compressed so that the thickness of the bent portion (10a) is gradually increased and the difference in length between the inner side and the outer side of the bent portion is increased. The pipe manufacturing method is characterized in that the first press-molding surface (10t) is formed so as to extend straight at the same time as the area becomes smaller.

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