JP5291306B2 - Different diameter pipe joint - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a different diameter pipe joint in which a weld zone is eliminated, and reliability to leakage is improved. <P>SOLUTION: The different diameter pipe joint has a bent region and an expanded pipe region integrally formed from one pipe stock. The bent region has a first straight line part and a second straight line part connected at the bent part, the inner wall face of the first straight line part is formed as a first press-formed face at least in the vicinity the bent part, the inner wall face of the second straight line part is formed as a second press-formed face at least in the vicinity of the bent part, and the first press-formed face and the second press-formed face are directly connected at the inner circumferential side of the inner wall face of the bent part or are close each other. The expanded pipe region has: an almost cylindrical large-diameter part; an almost cylindrical small-diameter part; and a shift part shifted therebetween, and the sheet thickness of the shift part is larger than that of the large-diameter part and also larger than that of the small-diameter part. <P>COPYRIGHT: (C)2009,JPO&amp;INPIT

Description

  The present invention relates to a different diameter pipe joint.

  Various different diameter pipe joints are known.

  13 and 14 show an example of a conventional different diameter pipe joint. The conventional different diameter pipe joint 210 is formed by joining the cut products 210a and 210b and the pipe 210c by welding at a position indicated by an arrow α.

In addition, Patent Document 1 discloses a pipe obtained by joining two parts.
JP-A-9-1247

  A pipe obtained by joining two parts by welding or the like has low reliability against leakage.

  An object of the present invention is to provide a different-diameter pipe joint in which a welded portion is eliminated and the reliability against leakage is improved.

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

(1) A different diameter pipe joint having a tube expansion region and a bending region integrally formed from one pipe material,
The expansion region has a substantially cylindrical large diameter portion, a substantially cylindrical small diameter portion, and a transition portion that transitions between them, and the thickness of the transition portion is larger than the thickness of the large diameter portion. And it is larger than the plate thickness of the small diameter part,
The bent region has a first straight portion and a second straight portion connected by the bent portion, and an inner wall surface of the first straight portion is formed as a first press molding surface at least near the bent portion, and the second The inner wall surface of the straight portion is formed as a second pressing molding surface at least near the bent portion, and the first pressing molding surface and the second pressing molding surface are directly connected on the inner peripheral side of the inner wall surface of the bending portion. Or joints with different diameters characterized by being close to each other.

(2) The above-mentioned different-diameter pipe joint, wherein the diameter of the large-diameter portion is at least twice the diameter of the small-diameter portion.

(3) The above-mentioned different-diameter pipe, wherein the plate thickness on the inner circumference side of the first straight portion and the plate thickness on the inner circumference side of the second straight portion are gradually increased toward the bent portion. Fitting.

(4) The aforementioned different-diameter pipe joint characterized in that the outer wall surface of the first straight portion and the outer wall surface of the second straight portion are straight and indented near the inner peripheral side of the bent portion.

(5) The aforementioned different-diameter pipe joint, wherein the transition portion extends in a tapered shape.

(6) The aforementioned different diameter pipe joint, wherein the transition portion extends in the radial direction.

(7) The above-mentioned different-diameter pipe joint, wherein a press-fitting seat surface is provided on the outer peripheral side of the bent portion.

  A preferred method and apparatus for producing the different diameter pipe joint of the present invention is as follows.

(I) a punch having a substantially cylindrical large-diameter portion, a substantially cylindrical small-diameter portion, and a transition portion transitioning between them, the substantially cylindrical large-diameter portion, and the substantially cylindrical small-diameter portion; The pipe-shaped workpiece is expanded by a punch and a die, and is inserted into a die having a transition portion that moves between them, and a substantially cylindrical large diameter portion, and a substantially cylindrical small diameter portion, In a method of forming a pipe having a transition portion that transitions between them, when the pipe-shaped workpiece is expanded, the plate thickness of the transition portion is larger than the plate thickness of the large diameter portion, and the small diameter A pipe expansion method characterized by being formed so as to be larger than the plate thickness of the portion.

(Ii) The pipe expanding method described above, wherein the pipe is formed so that the diameter of the large-diameter portion of the pipe is at least twice the diameter of the small-diameter portion of the pipe.

(Iii) When the end of the large-diameter portion of the punch is located at the same level as the start end of the large-diameter portion of the die, the end of the small-diameter portion of the punch is at a position before reaching the start end of the small-diameter portion of the die, When the end of the small diameter portion of the punch is located at the same level as the start end of the small diameter portion of the die, the end of the large diameter portion of the punch is located between the start end and the end of the large diameter portion of the die. Pipe expansion method.

(Iv) The die has a substantially cylindrical large-diameter portion, a substantially cylindrical small-diameter portion, and a transition portion that transitions from the end of the large-diameter portion to the beginning of the small-diameter portion,
In order to expand the diameter of the pipe-shaped workpiece to more than twice and form the expanded pipe, the punches inserted into the die are substantially cylindrical, corresponding to the large diameter part, small diameter part and transition part of the die, respectively. A large-diameter portion, a substantially cylindrical small-diameter portion, and a transition portion that transitions from the end of the large-diameter portion to the beginning of the small-diameter portion,
When the end of the large diameter portion of the punch is located at the same level as the start end of the large diameter portion of the die, the end of the small diameter portion of the punch is at a position before reaching the start end of the small diameter portion of the die,
When the end of the small diameter portion of the punch is located at the same level as the start end of the small diameter portion of the die, the end of the large diameter portion of the punch is located between the start end and the end of the large diameter portion of the die,
A pipe expansion device characterized in that the diameter of the large diameter portion of the die and punch is at least twice the diameter of the small diameter portion of the die and punch, respectively.

  ADVANTAGE OF THE INVENTION According to this invention, the different diameter pipe joint which improved the reliability with respect to a leak can be provided.

  Such a different diameter pipe joint is easy to accurately control the shape and thickness.

In particular, when the thickness of the inner circumference side of the first linear portion and the thickness of the inner circumference side of the second linear portion are gradually increased toward the bent portion, the shape and thickness are particularly accurately controlled. In particular, if the outer wall surface of the first straight portion and the outer wall surface of the second straight portion are not concave and straight near the inner peripheral side of the bent portion, the total length of the different diameter pipe joint is limited. The case can secure a long straight part of the joint of different diameter pipes. In other words, the different diameter pipe joint can be made compact.

  In particular, when the diameter of the large-diameter portion is more than twice the diameter of the small-diameter portion, only the different-diameter pipe joint obtained by joining is used, and the different-diameter pipe joint of the present invention is effectively used. Can do.

  In particular, when a press-fitting seat surface is provided on the outer peripheral side of the bent portion, the press-fit reliability is improved, and leakage can be guaranteed.

Best Mode for Carrying Out the Invention

  According to the present invention, the expanded region of the different diameter pipe joint having the expanded region and the bent region integrally formed from one pipe material includes a substantially cylindrical large diameter portion, a substantially cylindrical small diameter portion, and And a transition part that transitions between the two. The plate thickness of the transition portion is larger than the plate thickness of the large-diameter portion and larger than the plate thickness of the small-diameter portion. The bend region has a first straight line portion and a second straight line portion connected by the bend portion. The inner wall surface of the first straight portion is formed as a first press molding surface at least near the bent portion, and the inner wall surface of the second straight portion is formed as a second press molding surface at least near the bent portion. 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.

  Preferably, the diameter of the large diameter portion is twice or more than the diameter of the small diameter portion.

  Preferably, 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 are gradually increased toward the bent portion.

  Preferably, the outer wall surface of the first straight portion and the outer wall surface of the second straight portion are straight and not concave near the inner peripheral side of the bent portion.

  Preferably, the transition portion extends in a taper shape or extends in the radial direction. Note that the transition portion includes one formed in a step shape and one formed in a curved shape.

  Preferably, a press-fitting seat surface is provided on the outer peripheral side of the bent portion.

About the bending region The bending region in the different-diameter pipe joint of the present invention can be manufactured by using a method for manufacturing a pipe having a bending portion described later. That is, it is possible to manufacture a bent region in a different diameter pipe joint of the present invention from a bent portion of a pipe manufactured by the method shown below, and a first straight portion and a second straight portion connected by the bent portion. is there.

  A method for manufacturing a pipe having a bent portion will be described.

  Preferably, when manufacturing a bending part, a punch or a metal core is used as a pressing member.

  Preferably, 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.

  Preferably, when the first punch and the second punch or the metal core are brought close to each other, 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.

  Preferably, when the first punch and the second punch or the metal core are brought close to each other, the punches are made close to each other at a right angle to the metal core, but may be made closer 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.

  In the different diameter pipe joint of the present invention, the first straight portion and the 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.

  Preferably, 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 are gradually increased toward the bent portion. 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.

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

About a pipe expansion area The pipe expansion area in the different diameter pipe joint of this invention can be manufactured using the pipe expansion method mentioned later. That is, it is possible to manufacture the expanded region in the different diameter pipe joint of the present invention from the expanded pipe manufactured by the method described below.

  A pipe expansion method will be described.

  Preferably, when manufacturing a pipe expansion pipe, one type of punch and die are used as a pair, and a pipe-like workpiece (pipe material) is expanded in one pipe expansion process and at a pipe expansion ratio of about twice or more. A tube expansion region having a substantially cylindrical large-diameter portion, a substantially cylindrical small-diameter portion, and a tapered portion that transitions between them is manufactured.

  Typically, the pipe-shaped work (pipe material) is made of STKM11A, the inner diameter is 15.9 mm, the outer diameter is 19.1 mm, the plate thickness is uniform (identical) over the entire length, and is 1.6 mm.

  Such a workpiece (pipe material) is more likely to be cracked or buckled unless the punch and die structure is well designed than aluminum. For example, when the taper angle of the taper portion of the punch is too large, the pressing force (compression force) of the punch against the workpiece becomes excessive, and the workpiece tends to buckle. On the other hand, when the taper angle of the taper portion of the punch is too small, no problem occurs when the tube expansion rate is small. However, when the tube expansion rate is large (for example, exceeding 70%), the work is cracked. As described above, it is not easy to set the tube expansion rate to an appropriate value (particularly to increase the tube expansion rate) by being prevented by the conflicting phenomenon of cracking and buckling.

  When expanding the pipe, if the thickness of the taper of the pipe is larger than the thickness of the other parts of the pipe (that is, the large diameter part and the small diameter part), the pipe will crack even if the pipe expansion rate is increased. Does not occur, and the phenomenon of buckling does not occur. For example, even with the above-described workpiece, the pipe can be expanded about twice or more while suppressing the occurrence of cracking and buckling.

  Preferably, the die processing hole comprises a substantially cylindrical large-diameter portion, a substantially cylindrical small-diameter portion, and a tapered portion extending in a transition region therebetween. Corresponding to the shape of the hole for processing such a die (that is, the large diameter portion, the small diameter portion and the taper portion), the punch has a substantially cylindrical large diameter portion and a substantially cylindrical small diameter portion, respectively. It has a taper that extends into the transition region between them.

  As is well known, the punch is inserted into a hole for machining a die to expand a pipe-shaped workpiece, that is, a pipe material. The outer diameter of the pipe material is the same as the diameter of the small diameter portion of the die processing hole.

  Preferably, the large diameter portion of the die and punch is set to be approximately twice or more than the small diameter portion. For example, when the diameter of the small diameter portion is around 15 mm, the diameter of the large diameter portion is set to around 30 mm or more.

  Preferably, a plate is provided on the lower end surface of the die, the lower end of the processing hole of the die is closed, the pipe material is inserted into the processing hole of the die from above, and the lower end of the pipe material is in contact with the plate, The pipe material is stopped, and the pipe material is set up in a state where it enters the die hole. After that, the punch is inserted into the work from its upper end opening while keeping the punch and die processing hole and the pipe material (work) coaxial.

  When the punch is pushed down, the workpiece (pipe material) is gradually expanded in the radial (radial) direction by the taper portion of the punch, and the pipe expansion process proceeds. Further, the punch is pushed down, and the taper portion of the punch hits the taper portion of the die through the work. At this time, the pipe material pipe expansion process is completed. The expanded pipe is pressed tightly between the punch and the die, particularly at the large diameter portion and the taper portion thereof.

  As described above, in the pipe expanded from one pipe material (work), the plate thickness of the taper portion is larger than the plate thickness of the large diameter portion and larger than the plate thickness of the small diameter portion.

  Preferably, the die has a substantially cylindrical large-diameter portion, a substantially cylindrical small-diameter portion, and a tapered portion that transitions from the end of the large-diameter portion to the start end of the small-diameter portion.

  The punch is inserted into a die in order to expand the diameter of the pipe more than twice, corresponding to the large diameter portion, small diameter portion and taper portion of the die, And a substantially cylindrical small-diameter portion and a tapered portion that transitions from the terminal end of the large-diameter portion to the start end of the small-diameter portion.

  Preferably, when the end of the large-diameter portion of the punch is located at the same level as the start end of the large-diameter portion of the die, the end of the small-diameter portion of the punch is at a position before reaching the start end of the small-diameter portion of the die. Set to. When the end of the small diameter portion of the punch is located at the same level as the start end of the small diameter portion of the die, the end of the large diameter portion of the punch is positioned between the start end and the end of the large diameter portion of the die. Set.

  It is preferable that the diameters of the large diameter part and the small diameter part of the die are at least twice the diameters of the large diameter part and the small diameter part of the punch, respectively.

  In the application documents of the present application, the term “substantially cylindrical” is not limited to “cylindrical” in a strict sense, but includes, for example, a slightly tapered shape or a shape close to that. After being expanded, the expanded pipe is more likely to be pulled out of the die hole if it is "substantially cylindrical" with a slight taper rather than an exact cylindrical shape.

  Furthermore, it is also possible to mold the transition part extending in the radial direction. In that case, after manufacturing the pipe which has a taper-shaped transition part using the above-mentioned pipe expansion method, the further pipe expansion process is performed.

  In this case, first, a pipe having a tapered transition portion is disposed on a die in which a transition portion between the large diameter portion and the small diameter portion extends in the radial direction. Further, a punch having a radially extending lower surface is placed in the pipe. The inner wall surface of the small-diameter portion of the pipe may be restrained by providing a small-diameter portion corresponding to the punch, or may be restrained by providing a corresponding cored bar.

  Next, the punch is moved toward the die to press the pipe. The tapered transition portion of the pipe extends in the radial direction between the lower surface extending in the radial direction of the punch and the upper surface extending in the radial direction of the die. The thus formed transition portion extending in the radial direction of the pipe is obtained by compressing the tapered transition portion of the pipe in the advancing direction of the punch. Therefore, the thickness of the transition portion extending in the radial direction of the pipe changes so as to be larger than the thickness of the tapered transition portion of the pipe, and therefore the thickness of the large diameter portion and the small diameter portion of the pipe. It gets bigger.

Regarding the bent region and the expanded region, in the joint having a different diameter of the present invention, the bent region can be formed first, and then the expanded region can be formed. For example, first, a pipe having a bent portion is formed by the above-described method for manufacturing a pipe having a bent portion. Next, the molded pipe is fixed, and the expanded region is formed by the above-described pipe expansion method. Note that the tube expansion region may be formed first, and then the bending region may be formed.

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

  FIG. 1 is a partial sectional view showing a different diameter pipe joint according to one embodiment of the present invention. FIG. 2 is a top view of the different diameter pipe joint of FIG.

  The different diameter pipe joint 110 has a bending region R and a tube expansion region S that are integrally formed from one pipe material.

  The bend region R includes a first straight portion 110b and a second straight portion 110c that are connected by the bend portion 110a. The plate thickness on the inner peripheral side 110h of the first straight portion 110b and the plate thickness on the inner peripheral side 110h of the second straight portion 110c are gradually increased toward the bent portion 110a. Further, the outer wall surface 110g of the first straight portion 110b and the outer wall surface 110g of the second straight portion 110c are straight and have no dents near the inner peripheral side 110h of the bent portion 110a.

  The inner wall surface 110f of the first straight part 110b is formed as a first press molding surface 110t at least near the bent part 110a.

  The inner wall surface 110f of the second straight portion 110c is formed as a second press molding surface 110m at least near the bent portion 110a.

  The first press molding surface 110t and the second press molding surface 110m are directly connected to each other on the inner peripheral side 110h of the inner wall surface 110f of the bent portion 110a, or are close to each other.

  The tube expansion region S includes a substantially cylindrical large-diameter portion 103a, a substantially cylindrical small-diameter portion 103b, and a transition portion 103c that moves between them. The diameter of the large diameter portion 103a is at least twice the diameter of the small diameter portion 103b.

  The plate thickness of the transition portion 103c is larger than the plate thickness of the large diameter portion 103a and larger than the plate thickness of the small diameter portion 103b.

  In the example shown in FIGS. 1 and 2, a part of the transition portion 103c extends in the radial direction.

For bend region with reference to Figures 3-6 illustrating the pipe manufacturing process having a bend region. In FIGS. 3 to 6, the bent region is shown upside down with respect to FIGS. 1 and 2 for the sake of explanation. The expanded mold area and the working molds arranged corresponding to the punch and the cored bar are not shown for explanation. The parts corresponding to the parts of the different diameter pipe joint shown in FIGS. 1 and 2 are denoted by reference numerals with numerals reduced by 100.

  FIG. 3 is an explanatory diagram showing an example of a part of the manufacturing process of the bent region.

  The punch 12 functions as a pressing member. The core metal 14 functions as another pressing member.

  The pipe 10 has a first straight part 10b and a second straight part 10c connected by a bent part 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. 4 shows an enlarged view of the vicinity of the bent portion 10a of the preliminary pipe 10 shown in FIG.

  In FIG. 4, 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 case of manufacturing the bent portion, 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. A cored bar 14 is inserted into the 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 brought close to the core metal 14, and first, the second pressing molding surface 10m is formed on the inner wall surface of the second straight portion 10c by the core metal 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 to form 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 indicated by a solid line (FIG. 4) 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. A broken line 10q in FIGS. 3 to 4 indicates an outer wall surface forming end line of the bent portion 10.

  5 to 6 show a state where the molding process is completed.

  First, with reference to FIG. 5, the outer peripheral side 10 i of the outer wall surface of the bent portion 10 a is pressed by the punch 12 to the molding end line 10 q.

  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 straightened, and 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 linear portion 10c is pressed against the upper surface 14a of the core metal 14 and is straightened to extend the pressing surface in a straight line. 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 circumferential side of the bent portion 10a is reduced, and at the same time, the second pressing molding surface 10m is formed to be 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. 6 is an explanatory view for showing the press-molding surface in the present invention in more detail.

  With reference to FIG. 6, 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, the C region of the second straight portion 10c of the pipe 10 has an outer wall surface that 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. 6, the 1st press molding surface 10t of the 1st linear part 10b and the 2nd linear part 10c The distance E from the second press-molding surface 10m is preferably 1 mm or less (more preferably 0.5 mm or less). The distance E can be made 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. 7 is a schematic cross-sectional view showing an example of a pipe having a bent portion.

  Table 1 shows many pipes shown in FIG. 7, and any four pipes (samples 1 to 4) are selected from them, and the thickness of the inner peripheral side of these pipes (samples 1 to 4) is measured. The results are shown.

In FIG. 7, the measurement locations corresponding to Table 1 are indicated by rounded numbers, the first punch side is indicated by P, and the second punch or core metal side is indicated by 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.

  In addition, the shape and arrangement | positioning of a pipe, a punch, and a metal core 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. 3 to 6, the second press molding surface 10 m is formed before the first press molding surface 10 t is formed, but the reverse may be possible, and the first press molding surface 10 t You may form the 2nd press molding surface 10m simultaneously.

  The bent portion 10a shown in FIGS. 3 to 6 corresponds to the bent portion 110a shown in FIGS. In addition, the driving tool seating surface 110u is formed on the outer peripheral side 110i of the bent portion 110a by a further process that is not described. Further, the outer wall surface 110g on the outer peripheral side 110i of the bent portion 110a protrudes greatly outward, and this is formed by using a punch having a corresponding shape (not shown).

For tube expanding region by 8-10 explaining a manufacturing process of pipes having a tube expanding region. Note that the bending area is not shown for easy understanding. The large-diameter portion 103a, the small-diameter portion 103b, and the transition portion 103c of the different-diameter pipe joint 110 shown in FIGS. 1 and 2 correspond to a large-diameter portion, a small-diameter portion, and a tapered portion of the pipe 3, which will be described later.

  8-10 has shown the example of a part of manufacturing process of a pipe expansion area | region.

  As shown in FIG. 8, the punch 1 has a substantially cylindrical large-diameter portion 1a, a substantially cylindrical small-diameter portion 1b, and a tapered portion 1c. The taper portion 1c extends in a transition region between the end of the large diameter portion 1a and the start end of the small diameter portion 1b. In other words, the taper portion 1c is shifted from the end of the large diameter portion 1a to the start end of the small diameter portion 1b.

  The diameter (2D) of the large diameter portion 1a of the punch 1 is twice the diameter (D) of the small diameter portion 1b.

  The die 2 has a processing hole. The processing holes of the die 2 correspond to the outer shape of the punch 1, that is, the continuous outer wall surface shape of the large-diameter portion 1a, the small-diameter portion 1b, and the tapered portion 1c. It consists of a substantially cylindrical small-diameter portion 2b and a tapered portion 2c.

  The taper portion 2 c of the die 2 has the same taper angle as the taper portion 1 c of the punch 1. The diameter (D + 2t) of the small diameter portion 2b of the processing hole of the die 2 is the same as the outer diameter (D + 2t) of the pipe-like workpiece 3. Here, t is the thickness of the workpiece 3. The plate thickness of the work 3 is uniform (same) over the entire length.

  A plate 4 is detachably provided on the lower end surface of the die 2. Thereby, the lower end of the small diameter portion 2b of the processing hole of the die 2 is closed.

  In such a state, the lower end portion of the pipe-like workpiece 3 is inserted downward from the upper end opening portion of the large diameter portion 2a of the machining hole of the die 2 in FIG.

  As shown in FIG. 8, the pipe-shaped workpiece 3 stops when the lower end of the pipe-shaped workpiece 3 comes into contact with the upper surface of the plate 4. As a result, the pipe-like workpiece 3 is raised in a form that enters the machining hole of the die 2.

  As shown in FIG. 9, when the punch 1 is lowered in the direction of the arrow W (that is, the downward direction in the figure) while the punch 1, the processing hole of the die 2 and the workpiece 3 are kept coaxial (X), first, The small diameter portion 1b enters the upper end opening of the workpiece 3, and then the taper portion 1c of the punch 1 reaches the upper end opening of the workpiece 3, and the upper end portion of the workpiece 3 is gradually moved by the taper portion 1c of the punch 1. The tube is expanded in the radial (radial) direction.

  When the punch 1 is further lowered and the end of the large-diameter portion 1a of the punch 1 (the lower end in FIGS. 8 to 10) is located at the same level as the starting end (the upper end in FIGS. 8 to 10) of the large-diameter portion 2a of the die 2. The end of the small-diameter portion 1b of the punch 1 (the lower end in FIGS. 8 to 10) is at the front position where it does not reach the starting end (the upper end in FIGS. 8 to 10) of the small-diameter portion 2b of the die 2.

  When the punch 1 is further lowered and the end of the small diameter portion 1b of the punch 1 (the lower end in FIGS. 8 to 10) reaches the same level as the start end (the upper end in FIGS. 8 to 10) of the die 2, the punch 1 1 is located between the starting end (upper end in FIGS. 8 to 10) and the end (lower end in FIGS. 8 to 10) of the large diameter portion 2a of the die 2. ing.

  As shown in FIG. 10, when the punch 1 further descends in the direction of the arrow W, the taper portion 1 c of the punch 1 abuts against the taper portion 2 c of the die 2 through the workpiece 3. At this time, the pipe expansion process ends.

  Thereafter, although not shown, the punch 1 is pulled out from the processing hole of the die 2, and the pipe that has been expanded is also extracted from the processing hole of the die 2.

  The optimum taper angle (θ) of the taper portion 1c of the punch 1 can vary depending on the material and dimensions of the work 3, but is preferably 25 to 32 degrees, for example. If the taper angle (θ) is too large, the workpiece 3 tends to buckle at the portion indicated by A in FIG. On the other hand, if the taper angle (θ) is too small, the work 3 tends to crack at the site indicated by B in FIG.

Experimental Example FIG. 11 is a longitudinal section showing an example of a tube expansion region manufactured by the steps shown in FIGS.

  In FIG. 11, the codes | symbols 1-5 show the location which measured plate | board thickness about the pipe expanded.

Table 2 shows the measured thickness values of the portions indicated by reference numerals 1 to 5 of the pipe.

  The dimensions of the pipe-shaped workpiece (pipe material) before the pipe expansion process are as follows. Over the entire length of the workpiece, the plate thickness (t) is 1.6 mm, the outer diameter is 19.1 mm, and the inner diameter is 15.9 mm. It was. The material of the workpiece is STKM11A.

  Next, the expanded pipe will be described.

  As shown in FIG. 11, the upper end inner diameter of the large diameter portion of the pipe expansion pipe was 30.3 mm, and the lower end inner diameter of the small diameter portion was 15.9 mm.

  Further, as is apparent from Table 2, in the embodiment of the present invention, the taper portion of the pipe (location indicated by reference numeral 5) has a maximum plate thickness of 1.64 mm. The plate thickness of the small diameter portion of the pipe is the same plate thickness as that of the workpiece, that is, 1.6 mm. The large-diameter portion of the pipe has a thickness of 1.60 mm, which is the same as the thickness of the workpiece, and is 1.29 mm, which is the minimum value of the thickness of the starting end indicated by reference numeral 1. The plate thickness gradually decreases from the end of the part toward the start. That is, the plate thickness at the location indicated by reference numeral 3 is 1.46 mm, and the thickness at the location indicated by reference numeral 2 is 1.37 mm.

  On the other hand, in the comparative example, two types of punches and dies were used. First, the same pipe-shaped workpiece as that used in the example was preliminarily expanded using a sharp first punch having a small taper angle (θ). After that, the workpiece semi-processed product preliminarily expanded as described above was finally expanded by the punch 1 shown in FIGS.

  With reference to Table 2, an Example and a comparative example are compared.

  In the comparative example, the pipe thickness is drastically reduced. In particular, the thickness of the taper portion (location indicated by reference numeral 5) is 1.28 mm, which is smaller than the thickness (1.60 mm) of the workpiece before tube expansion processing.

  On the other hand, in the Example of this invention, the plate | board thickness of the taper part of a pipe is the largest 1.64 mm in the full length of a pipe, and is a measured value larger than another part.

  As one preferred example, a process of forming the expanded pipe 3 shown in FIGS. 8 to 10 into the expanded area S shown in FIGS. 1 and 2 will be described.

  First, the pipe 3 having a tapered transition portion is disposed on a die (not shown) in which a transition portion between the large diameter portion and the small diameter portion extends in the radial direction. Further, a punch (not shown) having a lower surface extending in the radial direction is arranged in the pipe 3. The inner wall surface of the small diameter portion of the pipe 3 is restrained by providing a small diameter portion corresponding to the punch.

  Next, the pipe 3 is pressed by moving the punch toward the die. The tapered transition portion of the pipe 3 is sandwiched and pressed between the lower surface extending in the radial direction of the punch and the upper surface extending in the radial direction of the die, and extends in the radial direction. The thus formed transition portion extending in the radial direction of the pipe is obtained by compressing the tapered transition portion of the pipe in the advancing direction of the punch. For this reason, the thickness of the transition portion extending in the radial direction of the pipe is larger than the thickness of the tapered transition portion of the pipe, and therefore larger than the thickness of the large diameter portion and the small diameter portion of the pipe.

  The transition portion 103c shown in FIGS. 1 and 2 further has a substantially cylindrical middle diameter portion, which can be formed by forming a corresponding middle diameter portion on the punch and processing.

An example of a process for manufacturing the different diameter pipe joint shown in FIGS. 1 and 2 by first forming the bent region R for the bent region and the expanded tube region and then forming the expanded tube region S will be described.

  First, the bending region R is formed from one pipe material by the above-described method for manufacturing a pipe having a bent portion. In the example shown in FIGS. 1 and 2, a driving tool seat surface, that is, a press-fit seat surface 110u, is formed on the outer peripheral side 110i of the bent portion 110a. Details of the configuration of the press-fitting seat surface 110u will be described later.

  Next, the molded pipe is fixed, and the tube expansion region S is formed by the pipe expansion method described above. In this case, a die (not shown) corresponding to the minimum R-bending portion shown in the region T is used.

  Finally, the molded pipe is fixed, and a minimal R-bending process is performed on the second straight portion 110c so as to be a portion indicated by the region indicated by the arrow T. In addition, the process of the minimum R bending process is arbitrary.

  In this way, the different diameter pipe joint shown in FIGS. 1 and 2 is obtained.

  Note that the tube expansion region may be formed first, and then the bending region may be formed.

  Next, the details of the configuration of the press-fitting seat surface 110u will be described.

  FIG. 12 is an explanatory view illustrating an example of a press-fitting process using a press-fitting seat surface. FIG. 15 is an explanatory diagram for explaining an example of a press-fitting process of a conventional different diameter pipe joint. FIG. 16 is an explanatory view for explaining another example of the press-fitting process of the conventional different diameter pipe joint.

  Conventionally, when a different diameter pipe joint (not shown) is formed by, for example, a brazing structure and screwed fastening, there is no problem in assembly if space can be secured for screw fastening.

  As shown in FIG. 15, when the different diameter pipe joint 310 is formed by the brazing structure and the press fitting, the different diameter pipe joint 310 has a press fitting seat surface 310 a, so that there is a problem in the press fitting process. There was no.

  However, as shown in FIG. 16, when the different diameter pipe joint 410 is formed by the pipe structure and the press-fit connection, there are the following problems and inconveniences caused by the problems.

(1) Needing out for press-fitting required → Increased cost due to increased molding process (2) Required jig for press-fitting → Increased cost due to increased man-hours for press-fitting (3) Thorough use of jigs in the general market is difficult → In a preferred embodiment of the present invention, the press-fit seat surface 110u is formed on the outer peripheral side 110i of the bent portion 110a of the different diameter pipe joint 110 as shown in FIG. Has been. The bent portion 110a connects the first straight portion 110b and the second straight portion 110c. The press-fitting seat surface 110u is provided at the upper part of the first straight part 110b, and can transmit the press-fitting load W to the lower part of the first straight part 110b. Preferably, the press-fitting seat surface 110u is configured as a flat surface orthogonal to the axis of the first straight portion 110b, and efficiently transmits the press-fit weight W to the lower portion of the first straight portion 110b. By folding the formation of the press-fitting seat surface 110u into the bending step of the bent portion 110a, an increase in the number of steps can be prevented. The area of the press-fitting seat surface 110u is preferably as large as possible so that the press-fit load W is received by the entire shaft. In the general market, in the case of such a component, if the seating surface is secured, the press-fitting operation is performed using the portion, so that the reliability of the press-fitting can be secured.

  The invention is not limited to the illustrated embodiment. The forming of the seating surface for the driving tool and the minimal R bending process are optional.

1 is a partial cross-sectional view showing a different diameter pipe joint according to an embodiment of the present invention. It is a top view of the different diameter pipe joint of FIG. It is explanatory drawing which shows a part of example of the manufacturing process of a bending area. FIG. 4 shows an enlarged view of the vicinity of the bent portion of the preliminary pipe shown in FIG. The state where the molding process is completed is shown. It is explanatory drawing for showing the state which the shaping | molding process was completed, and showing a press molding surface in more detail. It is a schematic sectional drawing which shows an example of the pipe manufactured by the manufacturing method of the bending part. It is explanatory drawing which shows a part of example of the manufacturing process of a pipe expansion area | region. It is explanatory drawing which shows a part of example of the manufacturing process of a pipe expansion area | region. It is explanatory drawing which shows a part of example of the manufacturing process of a pipe expansion area | region. It is a longitudinal cross-section which shows an example of the pipe expansion area | region manufactured by the process shown by FIGS. It is explanatory drawing which shows an example of the press-fit process using the press-fitting seat surface. It is a side view which shows an example of the conventional different diameter pipe joint. It is a top view of the different diameter pipe joint of FIG. It is explanatory drawing explaining an example of the press injection process of the conventional different diameter pipe joint. It is explanatory drawing explaining another example of the press injection process of the conventional different diameter pipe joint.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Punch 1a, 2a, 103a Large diameter part 1b, 2b, 103b Small diameter part 1c, 2c Taper part 2 Dies 3 Pipe-shaped workpiece (pipe material)
4 Plate 10 Pipe 10a, 110a Bent portion 10b, 110b First straight portion 10c, 110c Second straight portion 10d First end surface 10e Second end surface 10f, 110f Inner wall surface 10g, 110g Outer wall surface 10h, 110h Inner circumferential side 10i, 110i Outer peripheral side 10j, 10n Inner peripheral line 10k, 10p Outer peripheral line 10m, 110m Second press molding surface 10q Molding end line 10s Non-press molding surface 10t First press molding surface 12 Punch (an example of pressing member)
12a Punch side surface 12b Punch tip 14 Core metal (an example of a pressing member)
14a Upper surface 14b of cored bar 14b Core bar tip 14c Core bar tip surface 103c Transition part

Claims (5)

A different diameter pipe joint having a bent area and an expanded area integrally formed from one pipe material,
The bent region has a first straight portion and a second straight portion connected by a bent portion, and the outer wall surface of the first straight portion and the outer wall surface of the second straight portion are near the inner peripheral side of the bent portion, The thickness of the inner straight side of the first straight portion and the thickness of the inner peripheral side of the second straight portion are gradually increased toward the bent portion .
The expansion region has a substantially cylindrical large diameter portion, a substantially cylindrical small diameter portion, and a transition portion that transitions between them, and the transition portion extends in a taper shape or extends in a radial direction. The thickness of the transition portion is larger than the thickness of the large diameter portion and larger than the thickness of the small diameter portion, and the thickness gradually increases from the end of the large diameter portion to the starting end. Different diameter pipe joints characterized by being thinner .   2. The different diameter pipe joint according to claim 1, wherein the diameter of the large diameter portion is at least twice the diameter of the small diameter portion. The different diameter pipe joint according to claim 1 or 2 , wherein a press-fitting seat surface is provided on an outer peripheral side of the bent portion.   A method for manufacturing a different diameter pipe joint according to any one of claims 1 to 3, wherein the punch is moved toward the die to press the pipe material, and a substantially cylindrical large diameter portion; Forming a tube expansion region having a substantially cylindrical small diameter portion and a transition portion transitioning therebetween.   First, the punch is moved toward the die and the pipe material is pressed to form a tapered transition portion in the pipe material. After that, the tapered transition portion has a lower surface extending in the radial direction of the punch. A transition part that is sandwiched between and pressed by the upper surface of the die extending in the radial direction and that extends in the radial direction of the pipe is formed by compressing the tapered transition part in the advancing direction of the punch. The method according to claim 4.

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