JP3759502B2 - Pipe forming method - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
  The present invention relates to a pipe forming technique used for pipes arranged in heat exchangers and the like and pipe joints connecting pipes to pipes, and a processing method and a processing apparatus used for carrying out the processing method. It is about technology.
[0002]
[Prior art]
  2. Description of the Related Art Conventionally, parts are connected by piping to heat exchangers and the like provided in an automobile engine room, a water heater, and the like in order to send refrigerant, water and the like. In recent years, the above-mentioned devices have been improved in performance, and accordingly, the number of components has been increased, and each component has been arranged with high density. For this reason, the need for space saving has increased in piping, and piping that has been bent with a small radius of curvature is required in order to connect parts arranged at high density. This is because, if bending can be performed with a small radius of curvature, for example, a dead space generated at a bent portion of a U-shaped pipe can be reduced.
[0003]
  However, when bending with a small radius of curvature, there is a concern that the inside of the bent portion may buckle, and the outside of the bent portion has a concern that the wall thickness is reduced and the durability is deteriorated.
  For this reason, when bending with a small radius of curvature, it was impossible to perform bending beyond the minimum radius of curvature determined from the elongation rate and thickness of the piping material.
[0004]
  In order to solve such a problem, conventionally, the first step of bending the pipe with a normal bending R larger than the minimum curvature radius and the side wall of the bent portion of the bent pipe are restrained. However, a processing method consisting of a second step of pressing the pipe end portion with a pressing member is a known technique (see Patent Document 1), which enables bending with a smaller radius of curvature, and an R minimal elbow shape. Is realized.
[0005]
[Patent Document 1]
        JP 09-1247 A
[0006]
[Problems to be solved by the invention]
  However, the bending method in the prior art including the above-mentioned Patent Document 1 and the apparatus used for the bending method can be applied in one bending process, but a plurality of times of bending at close positions. Processing is not considered.
  That is, for example, in the case of forming an L-shaped pipe by bending once, a minimum R bending process is possible, but by bending twice at an adjacent position, for example,Concave pipeIn the case of molding, it becomes difficult to apply.
  That is, simplyL-shaped bending process is performed twice to form a concave pipeWhen trying to form, when using a bending apparatus such as a pipe bender, it is not possible to secure a holding allowance for a pipe once processed into an L shape. Also moldedConcave pipeThere is a concern that distortion occurs and the thickness becomes uneven.
  Also, with the above-mentioned processing method by bending twiceConcave pipeIs formed by the conventional processing method (FIG. 17).ConcaveAs shown in the plan view of the pipe, the pipe ends on both sides protrude unevenly, and the protruding portions 65 and 65 become unnecessary portions and need to be cut, and the protruding protruding portions 65 and 65 are lost. It was a thing.
[0007]
  In view of the above points, in the present invention, the dead space can be made as small as possible.Concave pipeAnd provide thisConcaveProvided is a processing method for forming a pipe without causing distortion or uneven thickness, and a processing apparatus used for the processing method.
  Moreover, it shape | molds with the said processing method and a processing apparatus.ConcavePipes can be realized with fewer processing steps and can be molded without loss.ConcaveA pipe processing method and a processing apparatus therefor are provided.
[0008]
[Means for Solving the Problems]
  The problems to be solved by the present invention are as described above. Next, means for solving the problems will be described.
[0009]
  That is, the present invention
  (A) a step of bending a pipe into a U shape by a cut-off bender and cutting the pipe to form a U-shaped pipe;
  (B) using a restraining jig, restraining the U-shaped pipe in a state in which the pipe ends on both sides thereof are projected;
  (C) Using a pressing member in which a core metal and two punches made of a pipe member surrounding the core metal are protruded, the core metal is simultaneously inserted into pipe ends on both sides of the U-shaped pipe. However, the step of inserting each pipe end into the gap between the cored bar and the pipe member,
  (D) By moving the pressing member in the direction of the restraining jig, the end portions of the gap-shaped portion are pressed at the end surfaces of the gap portions, and the bent portion outside the U-shaped pipe is moved by the cored bar. By pressing
  At the same time that the inside of the bent part of the U-shaped pipe is subjected to a minimal R bending process,
  Bending the outside of the bent portion of the U-shaped pipe along the shape of the core metal;
  Pipe forming method comprisingIt is.
[0010]
DETAILED DESCRIPTION OF THE INVENTION
  Next, embodiments of the invention will be described.
[0011]
  1 is a schematic view showing the first bending process, FIG. 2 is a perspective view of one side of a mold used in the second bending process, FIG. 3 is a front view of the other side mold, and FIG. FIG. 5 is a perspective view of a pressing member used in the second bending step, and FIG. 6 is a plan view of the same.
[0012]
  First, according to the present inventionConcaveThe processing steps until the pipe is formed will be described. In this embodiment,ConcaveThe pipe is formed of a hollow pipe member having a circular cross section.
  ConcaveThe pipe is formed by a first bending process in which a bending process with a large radius of curvature is performed, and a second bending process in which a bending process with a small radius of curvature is performed on the pipe member that has been subjected to a large R bending in the first process.
[0013]
  In the first step, a straight pipe member is bent with a large curvature radius by a known bending apparatus such as a pipe bender or a cut-off bender, and is cut into a predetermined length to form a U-shaped pipe. As shown in FIG. 1, the U-shaped pipe to be formed is bent by a bending apparatus 1 and then cut into a predetermined length by a pipe cutting machine 2. In other words, since both sides of the pipe 10 bent into a U-shape are cut out in parallel at the same time, the inclined portion 5 which is uneven in thickness due to the bending and can be cut off at the tip of the pipe 10 can be cut out. The end portions are aligned in parallel on both sides.
[0014]
  Next, the U-shaped pipe formed in the first step has the minimum R-bending portion of the present invention.ConcaveThe 2nd process processed into a pipe is explained.
  In the second step, the molds 11 and 13 as shown in FIGS. 2 and 3 are divided into two molds, and the restraining jig 20 (FIG. 4) configured by fitting the molds 11 and 13 together. A U-shaped pipe is inserted into the forming groove, and as shown in FIG. 5, a pressing member 15 protruding from the same side with two punches 16 and 16 is pressed to perform a minimal R bending process.
[0015]
  As shown in FIG. 4, the restraining jig 20 includes a pair of molds 11 and 13. The pair of molds 11 and 13 are formed in substantially the same shape, and the projections 12 and 12 are projected at positions not interfering with the molding on both sides of the mating surface of one mold 11 shown in FIG. The other mold 13 shown in FIG. 4 is provided with recesses 14 and 14 so that the protrusions 12 and 12 can be fitted. Then, by fitting the projections 12 and 12 of one mold 11 into the recesses 14 and 14 of the other mold 13, both molds 11 and 13 are securely fixed so as not to be displaced.
[0016]
  On the upper surface side of the mold 11 (or the mold 13), a molding groove 11a (or 13a) having a circular cross section for accommodating a U-shaped pipe and having a concave shape in a side sectional view is provided. The molding groove 11a is sized to match the outer diameter of the pipe 10, and the opening side end of the molding groove 11a is provided with steps 11c and 11c having diameters slightly larger than the width (diameter) of the molding groove 11a. ing. The lower ends of both sides of the molding groove 11a are formed in a square shape so as to be smaller than the radius of curvature of the U-shaped pipe 10, and the center convex portion 20d located between the openings on both sides has a U-shaped bottom. The shape roughly matches the radius of curvature of the pipe.
[0017]
  When the molds 11 and 13 are fitted to face each other, the molding grooves 11a and 13a for accommodating the U-shaped pipes of both molds overlap, and a pipe-shaped space that can accommodate and restrain the bent portion of the U-shaped pipe. A portion (molding groove) 20a (FIG. 4) is formed. Further, the steps 11c and 11c and the steps 13c and 13c of the mold on the other side overlap to form annular steps 20c and 20c. The steps 20c and 20c are provided to form a bulge 10c (FIG. 8) at the pipe end of the pipe, and will be described in detail later.
[0018]
  As shown in FIGS. 5 and 6, the pressing member 15 has two punches 16, 16 protruding from the front side (pressing direction side) of the main body 17. The punches 16 and 16 are arranged in parallel with an equal distance between the pipe ends on both sides so that the protruding pipe ends of the U-shaped pipe restrained by the restraining jig 20 can be pressed.
  The punch 16 includes a base portion 18 formed into a pipe shape, and a core bar 19 that protrudes downward from the center portion of the base portion 18 (with the restraining jig side downward). . The tip 19a of the metal core 19 is rounded and sharpened, the bent inner side 19b extends downward in a straight semi-cylindrical shape, and the outer side 19c is formed into an R shape (arc shape) that matches the shape to be bent. Has been.
  A pipe-shaped gap is formed between the inner periphery of the base 18 and the outer periphery of the core metal 19, and the end diameter of the pipe is determined by this gap, and the pipe surface of the pipe is determined by the end face 18b of the gap. The end is press-fitted. That is, the end diameter of the pipe to be processed can be corrected by inserting the pipe end into the gap. At the same time, the pitch of the pipe to be processed (distance between the pipe ends) can be corrected in accordance with the distance between the punches 16 and 16.
[0019]
  Here, a processing method using the restraining jig 20 and the pressing member 15 will be described.
  Figure 7 shows a U-shaped pipeConcaveIt is explanatory drawing which shows the process in which it processes to a pipe, (a) is sectional drawing which shows the inside of the restraint jig before a process, (b) is sectional drawing which shows the inside of the restraint jig after a process. FIG. 8 is an enlarged cross-sectional view showing the inside of the restraining jig in the middle of processing, FIG. 9 is a cross-sectional view showing the restraining jig for forming the bulge, (a) before bulge forming, and (b) after bulge forming. Show. FIG. 10 is a plan view of the ball mandrel, and FIG. 11 is an enlarged cross-sectional view of the inside of the restraining jig showing the use state of the ball mandrel.
[0020]
  When the U-shaped pipe is restrained by the both molds 11 and 13 described above, the bending direction of the U-shaped pipe and the direction perpendicular to the bending direction are restrained by the restraining jig 20 as shown in FIG. Although there is no gap, gaps 20e and 20e are formed on both sides of the lower portion of the space.
  Then, as shown in FIG. 7B, when the core metal 19 is inserted into the restraining jig 20 while pressing the pipe end of the U-shaped pipe by the pressing member 15, the bent portion of the U-shaped pipe is obtained. The outer side 10a is pushed into the gaps 20e and 20e to be expanded, and at the same time, the bent portion outer side R is formed along the shape thereof by pressing the front end portion of the cored bar 19. Further, the bent portion inner side 10b is pressed toward the inner side of the pipe along the inner side of the cored bar 19 so as to reduce the bending R and is subjected to the minimum R bending process. In addition, since the metal core 19 has entered the pipe without any gap, buckling does not occur in the bent portion inner side 10b.
[0021]
  Normally, when the pipe is bent, the thickness of the bent portion outer side 10a is reduced and the durability is lowered. However, in the present invention, the bent portion outer side 10a is processed while pushing the pipe end portion. , Can prevent the reduction of wall thickness. On the contrary, when the tube end is pushed in, the bent portion inner side 10b becomes thicker and becomes bent or buckled, but it can be prevented by the cored bar 19 inserted in the pipe.
  Furthermore, the protrusion inside the pipe end (FIG. 17) that occurs with the change in thickness due to the bending process described above can also be suppressed because the pipe end of the pipe is pressed, and a flat pipe end can be formed. HaveConcavePipes are formed. For this reason, no loss occurs.
[0022]
  Note that the lengths of the punches 19 and 19 protruding from the pressing member 15 are equal, and when pressing the tube end, no force is applied to both sides. For this reason, force is equally applied to the pipe ends on both sides, and the conventional L-shaped bending is repeated twice.ConcaveIt is possible to solve problems such as uneven thickness and distortion, which are a concern when obtaining pipes.
[0023]
  As described above, the U-shaped pipe is constrained by the restraining jig 20, and the both ends of the U-shaped pipe are simultaneously pressed by the pressing member.Concave shapeSince the mold was formed, it was subjected to two minimal R-bends at close positions without concern for thickness reduction and buckling.ConcavePipes can be formed.
  Also,ConcaveSimultaneously with the forming of the pipe, the terminal diameter can be corrected and the pitch can be corrected, and various processing steps can be performed at the same time.
[0024]
  In addition, as described above, the U-shaped pipe is pressed from the tube end side by the pressing member.ConcaveWhen forming a pipe, the bulge 10c can be simultaneously formed. That is, as shown in FIG. 8, when the tube end is pressed by the pressing member, the outside of the U-shaped pipe is bent, and the bent portion is sandwiched between the annular step 20 c and the tip of the punch base 18,ConcaveA protrusion is formed on the pipe end side of the pipe, and a bulge 10c is formed. In addition, there is no bulge by not providing the step 10c.ConcaveIt is also possible to mold the pipe.
[0025]
  Also, there is no molded bulgeConcaveIt is also possible to form a bulge on the pipe later. For example, as shown in FIG.ConcaveAn annular step 33b / 33b is provided on the pipe end side using a mold 33 having a groove provided in accordance with the shape of the pipe. And in the groove of the mold 33ConcaveThe pipe 10 is fitted and restrained.
  At this time,ConcaveThere should be no gap between the pipe 10 and the groove of the mold 33. And with the pressing member from the tube end sideConcaveWhen the pipe 10 is pressed,ConcaveSince the pipe 10 is constrained by the groove without a gap, bending occurs at the steps 33b and 33b, and the bent portion is sandwiched between the tip 18a and the step 33b of the base 18 of the pressing member, thereby forming the bulge 10c. is there.
  Like this, the bulgeConcaveSimultaneous molding at the time of pipe molding, orConcaveAfter the pipe is formed, it can be formed in a separate process.
[0026]
  Further, a ball mandrel 21 as shown in FIG. 10 can be used for the pressing member 15. The ball mandrel 21 is provided with a substantially spherical rocking body 23 at the tip of a straight cored bar 22. The diameter of the oscillating body 23 is slightly smaller than the inner diameter of the pipe 10, and the base of the oscillating body 23 is pivotally supported by a fulcrum shaft 24 fixed to the distal end side of the core metal 22 so as to be rotatable. Is provided.
  And the front-end | tip part of the metal core 22 is cut | disconnected diagonally, the inclination part 22a is provided, and it can be rotated to this inclination part 22a side. By attaching the ball mandrel 21 to the tip of the pressing member 15 and functioning as a punch, the rocking body at the tip can enter deep into the pipe and the diameter of the pipe can be made constant.
[0027]
  That is, as shown in FIG. 11, when the ball mandrel 21 is press-fitted from the pipe end portions on both sides of the pipe, the rocking body 23 at the tip of the ball mandrel 21 enters the inside of the pipe and presses downward along the inner surface of the pipe. Then, the bent portion outer side 10a of the pipe is pushed in. Moreover, since the spherical rocking body 23 moves along the bent portion of the pipe and enters the back side, the pipe diameter does not change between the straight portion and the bent portion. Furthermore, since the inner side of the bent portion is regulated by the surface of the rocking body 23, the inner buckling can be prevented.
  Thus, it is also possible to make the ball mandrel function as a punch for the pressing member.
[0028]
  With the above processing method and the processing equipment used for the processing methodConcaveThe pipe can be molded, so there is no need to bend it twice as in the conventional case.ConcaveSince the pipe can be formed, it can be processed with few steps and there is no concern about distortion due to uneven application of force. Also moldedConcaveSince the pipe end portion is flat and does not protrude unnecessarily, loss can be eliminated and cost reduction can be achieved. further,ConcaveSince the terminal diameter can be corrected, the pitch can be corrected, and the bulge can be formed together with the forming of the pipe, a variety of processing steps can be performed at the same time, and the number of processing steps can be reduced.
[0029]
  Here, the Example in the case of performing minimum R process to the hairpin-shaped U-shaped pipe which has a long straight part is demonstrated.
  FIG.HairpinIt is sectional drawing explaining the shaping | molding processing method of a pipe, (a) is a figure which shows the hairpin-shaped U-shaped pipe before a process, (b) is after a processHairpinIt is a figure which shows a pipe.
  As shown in FIG. 12 (a), when performing a minimal R-bending process on the U-shaped pipe 42 having a long straight portion in the form of a hairpin, a restraining jig 43 that holds both straight portions 42a and 42a of the U-shaped pipe; Processing is performed with a pressing mold 46 that presses the bending portion 42 b protruding outward from the restraining jig 43. In the restraining jig 43, two pipe-like restraining holes are opened in parallel according to the shape of the straight portion 42a of the hairpin-shaped U-shaped pipe, and both straight portions 42a of the hairpin-shaped U-shaped pipe are formed in the restraining hole. -42a is restrained.
  Further, the pressing mold 46 has a cross-sectional view omitted.ConcaveThe pressing groove 46a is recessed, and the bending portion 42b of the hairpin-shaped U-shaped pipe is inserted into the pressing groove 46a and pressed.
[0030]
  In the hairpin-shaped U-shaped pipe 42 in which the straight portions 42a and 42a on both sides are constrained by the restraining jig 43, core bars 47 and 47 are inserted in advance from the tube end side to the bent portion side, and the core It arrange | positions so that the front-end | tip part of gold | metal | money 47 * 47 may be located in the bending process part of a U-shaped pipe. The core bars 47 and 47 have a circular tip, the inside of the bent portion is linear, and the outside of the bent portion is formed in an arc shape in accordance with a desired bent shape.
[0031]
  When the pressing mold 46 is pressed against the bending portion 42b of the hairpin-shaped U-shaped pipe 42 thus restrained from the pressing groove 46a side, the bending portion 42b is deformed along the shape of the pressing groove 46a. Then, as shown in FIG. 12B, at the position where the pressing mold 46 and the restraining jig 43 are in contact with each other, the bending portion 42b has the same shape as the pressing groove 46a, and the minimum R bending processing is performed. Is completedHairpinThe pipe 52 is formed.
  And processedHairpinCompared with the hairpin-like U-shaped pipe 42 shown in FIG.
[0032]
  That is, in the processing method described above, the pipe is pressed by the pressing member provided with the cored bar. However, in this embodiment, the cored bars 47 and 47 are inserted into the pipe in advance. Then, pressing is performed by the pressing mold 46. By processing by such a processing method, when processing a pipe having a shape such as a hairpin having a long straight portion, the processing can be performed with a small operation.
[0033]
  The processing method of the hairpin-shaped U-shaped pipe in the present embodiment can be applied to the normal processing method described above, and conversely, the processing method of the hairpin-shaped U-shaped pipe in the present embodiment is described above. ofConcaveA pipe processing method can also be applied. That is, when the hairpin-shaped U-shaped pipe of this embodiment is formed, it can be processed by restraining the bending portion and pressing it with a pressing member having a metal core longer than the tube end portion. , Mentioned aboveConcaveIn the pipe processing method, a cored bar may be inserted in advance from the pipe end side and pressed from the bending part side.
[0034]
  Next, molding is performed by the processing method and processing apparatus described above.ConcaveThe pipe is shown in FIG. FIG.ConcaveIt is a top view which shows one form of a pipe, (a) no brazing material, (b) brazing material was installed.ConcaveFigure 14 shows a pipe.ConcaveIt is a top view which shows the form of a pipe, (a) without brazing material, (b) with brazing material installedConcaveFig. 15 shows a pipe.ConcaveIt is a top view which shows the restraining jig | tool for shape | molding a pipe.
  As shown in FIG.ConcaveThe pipe 40 is formed by the processing method and processing apparatus described above. TheConcaveThe pipe 40 is formed so that the radius of curvature of the bent portion inner side 40a is as close to zero as possible. By being formed in this way, it is possible to effectively use the space by arranging the rectangular parts so as to sandwich them.
  Also shown in FIG.ConcaveThe pipe 40 is formed with bulges 40b on the pipe end sides on both sides, and can be used as a pipe joint, so that two pipes can be joined even in a small space. As shown in FIG.ConcaveIn the pipe 40, a ring-shaped brazing material 41 is provided close to the bulge 40b. The brazing material 41 is made of a low melting point metal,ConcaveWhen connecting another pipe to the pipe 40, the pipe 40 is securely fixed to enhance the sealing performance.
[0035]
  In addition, by using a constraint jig with a different groove shape, a different shape as shown in FIG.ConcaveThe pipe 50 can also be formed. TheConcaveThe pipe 50 can be formed by a restraining jig configured by opposing two molds 53 each having a semi-ring-shaped forming groove 53a as shown in FIG.
  In other words, depending on the application, two minimal R-bending was performed at close positions.ConcaveThe pipe can be processed into various shapes.
  As shown in FIG.ConcaveThe pipe 50 has bulges 50a formed on both pipe end sides, and can be used as a pipe joint, as shown in FIG. 14 (b).ConcaveIn the pipe 50, a ring-shaped brazing material 51 is provided close to the bulge 50a.
[0036]
  WhereConcaveAn example of using a pipe will be described with reference to FIG.
  FIG. 16 illustrates the present invention.ConcaveIt is explanatory drawing which compares a pipe with the pipe in a prior art,
(A) is conventionalConcaveExplanatory drawing which shows the usage example of a pipe, (b) is the present inventionConcaveIt is explanatory drawing which shows the usage example of a pipe.
  For example, as shown in FIG. 16A, when a pipe formed by bending according to the prior art is inserted into a metal mass 26 having holes 26a formed in accordance with the shape of the pipe end of the pipe. The inside of the bent part of the pipe is caught and cannot be inserted all the way into the pipe, and the pipe 26 protrudes greatly. However, as shown in FIG.ConcaveWhen the pipe is inserted, theConcaveSince the inside of the bent portion of the pipe is bent to a minimum R, the straight portion is longer than the conventional one and can be inserted deep inside the mass 26.
  That is, compared with the protrusion length L1 of the conventional pipe,ConcaveThe protrusion length L2 of the pipe is small, and the area occupied by the pipe is small. For this reason, the present inventionConcaveBy using pipes, the conventional dead space can be made available.
[0037]
  AndConcaveFor example, the pipe is disposed in a heat exchanger installed in a water heater or the like. So as mentioned above,ConcaveWhen a pipe is used, the projecting length of the pipe is reduced and the area occupied by the pipe is reduced, so that a heat exchanger that is smaller than the conventional one can be realized.
[0038]
【The invention's effect】
  Since the present invention is configured as described above, the following effects can be obtained.
[0039]
  That is, as shown in claim 1,
  (A) a step of bending the pipe into a U-shape by a cut-off bender (see FIG. 1) and cutting the pipe to form a U-shaped pipe;
  (B) a step of restraining the U-shaped pipe (pipe 10 in FIG. 7 (a)) with the restraining jig 20 (FIG. 7) in a state where the pipe ends on both sides thereof are projected;
  (C) Using a pressing member 15 (FIG. 5) in which two cores 19 (FIG. 5) and two punches 16 (FIG. 5) made of a pipe member (FIG. 5: base 18) surrounding the core metal are projected. , While simultaneously inserting the cored bar 19 (FIG. 5) into the pipe ends on both sides of the U-shaped pipe, respectively, the pipe ends are respectively connected to the cored bar 19 (FIG. 5), Inserting into a gap between the pipe member (FIG. 5: base 18);
  (D) By moving the pressing member pressing member 15 (FIG. 5) in the direction of the restraining jig pressing member 20 (FIG. 7A), the end surface 18b (FIG. 7A) of the gap portion is moved. In addition to pressing the tube ends, pressing the bent portion outer side 10a (FIG. 8) of the U-shaped pipe with the core metal 19 (FIG. 8)
  At the same time that the bending portion inner side 10b (FIG. 8) of the U-shaped pipe is minimally bent,
  Bending the bent portion outer side 10a (FIG. 8) of the U-shaped pipe along the shape of the core;
  Pipe formingIt is a construction method.
  This eliminates distortion and uneven thicknessConcaveThe pipe can be formed.
  Also with the prior artConcave pipe with two L-shapesIn order to mold the material, two minimal R-bending processes were required.ConcaveSince pipes can be molded, it requires fewer stepsConcavePipes can be processed.In addition, when processing from a U-shaped pipe to a concave pipe, no protrusions that need to be cut after forming the concave shape are formed at the pipe ends on both sides of the pipe, thereby preventing loss. .
[0040]
  Also,If a concave pipe formed by the processing method of the present invention is used,,
  When allocating to heat exchangers, etc., the pipe occupying area is reduced and extra dead space can be saved, so the available space increases and pipes are efficiently placed between parts that are densely arranged. Can be arranged.
[Brief description of the drawings]
FIG. 1 is a schematic view showing a first bending step.
FIG. 2 is a perspective view of one side of a mold used in a second bending process.
FIG. 3 is a front view of a mold on the other side.
FIG. 4 is a plan view of a pair of molds.
FIG. 5 is a perspective view of a pressing member used in a second bending process.
FIG. 6 is also a plan view.
[Fig.7] U-shaped pipeConcaveExplanatory drawing which shows the process processed into a pipe.
FIG. 8 is an enlarged cross-sectional view showing the inside of a restraining jig in the middle of processing.
FIG. 9 is a sectional view showing a restraining jig for forming a bulge.
FIG. 10 is a plan view of a ball mandrel.
FIG. 11 is an enlarged cross-sectional view of the inside of the restraining jig showing the use state of the ball mandrel.
FIG.HairpinSectional drawing explaining the shaping | molding processing method of a pipe.
FIG. 13ConcaveThe top view which shows one form of a pipe.
FIG. 14ConcaveThe top view which shows another form of a pipe.
FIG. 15 shows another embodiment.ConcaveThe top view which shows the restraining jig | tool for shape | molding a pipe.
FIG. 16 shows the present invention.ConcaveExplanatory drawing which compares a pipe and the pipe in a prior art.
FIG. 17 is formed by a conventional processing method.ConcaveThe top view which shows a pipe.
[Explanation of symbols]
  1 Bending machine
  10 pipes
  10a Molding groove
  19 Core
  20 Restraint jig

Claims (1)

(A) a step of bending a pipe into a U shape by a cut-off bender and cutting the pipe to form a U-shaped pipe;
(B) a step of restraining the U-shaped pipe with a restraining jig in a state in which the pipe ends on both sides thereof are projected;
(C) Using a core member and a pressing member provided with two punches made of a pipe member surrounding the core metal, the core metal is simultaneously inserted into pipe ends on both sides of the U-shaped pipe. However, the step of inserting each of the tube end portions into the gap between the cored bar and the pipe member,
(D) By moving the pressing member in the direction of the restraining jig, the end portions of the U-shaped pipes are pressed by the cored bar while pressing the tube end portions at the end surfaces of the gap portions. By pressing
At the same time that the inside of the bent part of the U-shaped pipe is subjected to a minimal R bending process,
Bending the outside of the bent portion of the U-shaped pipe along the shape of the core metal;
A pipe forming method comprising:

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