JP5797538B2 - Curved pipe manufacturing equipment - Google Patents

Description

The present invention relates to a bent pipe manufacturing apparatus that manufactures a bent pipe by injection molding, and more particularly to a bent pipe manufacturing apparatus that can manufacture even a bent pipe having a large curvature with respect to the diameter.

  Production of a curved pipe by injection molding has been performed by an apparatus as disclosed in, for example, Patent Document 1 below. This apparatus is for manufacturing a so-called U-shaped bending tube, and has an outer mold for molding the outer peripheral side of the bending tube and an inner mold for molding the inner surface of the bending tube. Is a pair of left and right base core parts that form the linear parts at both ends of the U-shaped tube, which is a molded product, and a curved part of the U-shaped pipe that is connected to the inner ends of these base core parts via a movable shaft. It is the structure provided with the movable core part to do. By pulling the movable shaft, the movable core portion can be joined and integrated with the base core portion, and by releasing the pulling of the movable shaft, the movable core portion is separated from the base core portion and rotated in the direction of bending the axis of the U-shaped tube. It becomes possible to move.

  According to this apparatus, the inner core, in which the base core portion and the movable core portion are joined and integrated, and the left and right movable core portions are joined and integrated, is placed in the outer mold for injection molding. By unraveling the part, the movable core part slides in the U-shaped tube as the inner mold is pulled out, and comes out straight from both ends of the U-shaped tube. For this reason, it is possible to manufacture a U-shaped tube.

JP 2009-114700 A

  However, since such a U-shaped tube has a shape with a small curvature for the size of the diameter, it can be pulled out by operating one movable core portion connected to the base core portion with a movable shaft. Therefore, it is impossible to adopt the configuration as in Patent Document 1 for manufacturing a bent tube having a large curvature for the diameter.

  In other words, in a curved pipe with a small curvature relative to the size of the diameter, the arcuate contour on the outside of the movable core portion is small relative to the size of the diameter, so that the movable core portion can rotate and set its axis. In other words, even when the inner and outer arcuate contours are standing upright and leftward, the left and right widths can be kept relatively small compared to the size of the diameter. For this reason, it is possible for the movable core part to turn to the above-mentioned posture within the large diameter part for connection in the U-shaped tube. However, in the case of a curved tube with a large curvature relative to the size of the diameter, the movable core part must be long, and the left and right widths in an upright position are much larger than the size of the diameter. Therefore, it cannot be rotated in the U-shaped tube.

  In addition, in the conventional configuration as in Patent Document 1, in other words, the inner mold has one movable core portion in each of the left and right base core portions. Thus, it has been impossible to produce a twisted tube in which the axial centers of both ends are in a twisted positional relationship.

  Therefore, the present invention mainly enables the manufacture of a bent tube having a large curvature for the size of the diameter, and also enables the manufacture of a twisted tube in which the axial centers of both ends are in a twisted positional relationship. Objective.

As means for the open and closed possible outer mold, the inner mold housed within the outer mold, is configured cavities of the bend shape corresponding to the curved pipe having a curved portion, the molten resin into the cavity An apparatus for producing a bent pipe after molding by injection and removing the bent pipe as a molded product from the outer mold and the inner mold, wherein the inner mold bisects the inside of the bent pipe in the longitudinal direction, A pair of inner molds that can be contacted and separated from each other, and an inner mold for forming a bent portion of the bent pipe among these inner molds, an inner mold base carrier located on the most end side of the bent pipe, It has a plurality of inner-type bent portion carriers that are located on the tip side of the inner-type base carrier and mold the bent portion of the bent tube, and among the inner-type bent portion carriers, the inner-bend portion carrier at the tip includes By pulling, the inner base carrier and the inner bent portion carrier are aligned in the axial direction of the inner mold. The main traction means is fixed so as to be able to be separated from each other by being constrained to be integrated and loosened, and the inner mold on the end side of the bent pipe from the inner bent portion carrier at the tip of the inner mold bent portion carrier. A bent tube manufacturing device in which a follower pulling means that moves in a pulling direction by being pulled is fixed to the bent portion carrier, and the inner mold bent portion carrier is formed to be displaceable in a direction in which the axis of the inner mold is bent. Device.

  In this configuration, the inner mold having the bent portion of the curved pipe among the pair of inner molds that bisect the inside of the curved pipe in the longitudinal direction includes an inner mold base carrier and a plurality of inner mold bent section carriers, In the former stage, a constraint releasing step is performed in which the inner mold base carrier is relatively moved in the drawing direction to release the constraints of the plurality of inner mold bent portions so that they can be separated. By this restraint releasing step, a gap is formed between the plurality of inner-type bent portion carriers and between the inner-type base carrier and the inner-type bent portion carrier, and each inner-type bent portion carrier has at least the inner-type axis center. It can be displaced in the direction of bending. For this reason, each inner type bent portion carrier can be moved along the bent portion of the bent tube in the bent pipe, and the inner bent portion carrier can be moved by the relative traction of the inner bent portion carrier in the subsequent inner die removing process. It moves in the drawing direction within the curved pipe, and then comes out of the inner bent portion carrier on the base side in order, and is released from the mold.

  The plurality of inner-type bent portion carriers can be formed and released even in a curved pipe having a large curvature with respect to the size of the diameter, and a pair of inner molds having the inner-shaped bent portion carrier are Further, it is possible to form a twisted tube in which a middle portion of a U-shaped tube that is greatly curved is twisted.

  As described above, according to the present invention, since a plurality of inner-type bent portion carriers for forming a bent portion of the bent tube are provided, it is possible to manufacture a bent tube having a large curvature for the size of the diameter. In addition, it is possible to manufacture twisted tubes.

The perspective view which shows one side of an inner type | mold. The perspective view of the curved pipe which is a molded article. The top view and front view of a curved pipe, and a partially broken right side view. The perspective view which shows schematic structure of a metal mold | die. The perspective view which shows a pair of inner mold | type. A sectional view of an inner mold. The half sectional view of the decomposition | disassembly state of an inner type. Sectional drawing of a mold clamping process. AA sectional drawing of FIG. Sectional drawing of an injection process. BB sectional drawing of FIG. Sectional drawing of an outer mold opening process. Sectional drawing of an inner die cutting process. Sectional drawing of an inner die cutting process. Sectional drawing of the state which the inner die cutting process was completed.

An embodiment for carrying out the present invention will be described below with reference to the drawings.
FIG. 1 is a perspective view showing a main part of a bent pipe manufacturing apparatus for manufacturing a bent pipe 11 as shown in FIGS. 2 and 3 having a bent portion.

  The bent pipe 11 is used, for example, as a pipe through which a fluid passes in various apparatuses in addition to a drain pipe and a water supply pipe. As shown in FIG. It is a tube. More specifically, as shown in FIG. 3, both the plan view (see FIG. 3A), the front view (see FIG. 3B), and the side view (see FIG. 3C) are substantially L-shaped. In other words, it is a shape in which only one of the left and right directions is twisted 90 degrees around the axis in the middle of the semicircularly curved tube.

  That is, it has two bent portions 12 that form an arc shape obtained by dividing a circle into four equal parts, and a large-diameter portion 13 for connection formed at the end of these bent portions 12. However, since the two bent portions 12 are smoothly continuous with the same thickness, the bending direction of the shaft center is gradually changed at the bent portion, and the twisted portion or the twisted portion is applied. . The large-diameter portion 13 is linear in the axial direction, and a tapered portion 14 is formed between the large-diameter portion 13 and the bent portion 12.

  FIG. 4 shows a schematic structure of the mold 21 of the bent pipe manufacturing apparatus. As shown in this figure, an openable / closable outer mold 22 and an inner mold 23 accommodated in the outer mold 22 are provided.

  The outer mold 22 is configured so that a cavity 24 having a desired curved pipe shape can be formed around the inner mold 23. The inner mold 23 has a shape that bisects the inside of the curved pipe 11 at the middle point in the longitudinal direction, and is composed of a pair of inner molds 23 whose tips can be contacted and separated as shown in FIG. Since the bent tube 11 has the shape as described above, the pair of inner molds 23 are portions for forming the bent portion 12 of the bent tube 11 and have the same structure except for the tip surface.

  Since the pair of inner molds 23 have basically the same structure, only one of them will be described. As shown in FIG. 6, the inner mold 23 is composed of three members. One is a straight core 25 which is located on the most end side of the bent tube 11 and forms the large diameter portion 13 and the tapered portion 14 of the bent tube 11. The other two are bent cores 26 and 27 (the distal bent core 26 and the intermediate bent core 27) that are located on the distal end side of the straight core 25 and that form the bent portion 12 of the bent tube 11. These bent cores 26 and 27 are formed in the same size, and convex portions 27a and concave portions 26a that are fitted to each other are formed on the opposing surfaces. That is, a concave portion 26 a is formed at the rear end of the leading bent core 26, and a convex portion 27 a is formed at the leading end of the intermediate bent core 27. The convex portion 27a and the concave portion 26a have a shape that prevents rotation in the direction around the axis when joined.

  Similar convex portions 25 a and concave portions 27 b are also formed between the intermediate bent core 27 and the straight core 25. That is, the convex portion 25 a is formed at the tip of the straight core 25 and the concave portion 27 b is formed in the intermediate bent core 27.

  Although two bent cores 26 and 27 are provided in this example, the number of bent cores 26 and 27 may be three or more depending on the desired shape of the bent pipe 11. That is, two or more intermediate bent cores 27 may be provided.

  Of the pair of inner molds 23, the tip bending core 26 is formed with a convex portion 26b or a concave portion 26c for alignment so that the tips can be brought into contact with each other as described above. These convex portions 26b and concave portions 26c are formed in an appropriate shape, and are formed in a hemispherical shape as shown in FIGS. 6 and 1, or in a pyramid shape that can be prevented from rotating around the axis when fitted. You can also.

  In the inner mold 23, the cores 25, 26, and 27 are joined and integrated at the time of molding. On the other hand, the cores 25, 26, and 27 can be separated and the inner mold 23 can be pulled out from the bent pipe 11 at the time of die cutting. Means are provided for doing this. That is, as shown in FIGS. 6 and 7, through holes 25b and 27c are formed in the center of the straight core 25 and the intermediate bent core 27, and the leading bent core 26 is also communicated with the through holes 25b and 27c. An insertion hole 26d is formed, and the tip of the main traction means 28 is fixed to the insertion hole 26d.

  The main traction means 28 is constituted by an appropriate member such as a link mechanism, a cam mechanism, or a wire. In this example, a chain is used. The main traction means 28 composed of a chain has a degree of freedom of bending in one direction markedly higher than the direction of bending in the other direction among the directions in which the axis of the inner mold 23 is bent. It bends and easily displaces so as to extend straight at the straight portion.

  The main traction means 28 has a straight pipe 25 and an intermediate bent core 27 in a state of being skewered, and the traction and traction can be released based on conditions according to the shape of the bent pipe 11 to be manufactured. Installed.

  When the main pulling means 28 is pulled, the leading bent core 26 is pulled rearward (the end side of the bent tube 11), contacts the tip of the intermediate bent core 27 located on the rear side thereof, and the intermediate bent core 27 is Press against the straight core 25. That is, all the cores 25, 26, 27 are constrained so as to be aligned in the axial direction of the inner mold 23. As a result, all the cores 25, 26, 27 are integrated while the traction force is acting. Further, the leading bent core 26 is pulled out of the bent tube 11 by the pulling of the main pulling means 28.

  When the main traction means 28 is loosened and the restraint is released, all the cores 25, 26, 27 can be separated from each other, and the intermediate bending core 27 and the straight core 25 are arranged along the longitudinal direction of the main traction means 28. Relative movement and relative rotation in the direction of twisting the axis of the inner mold 23 are allowed. The latter relative rotation is possible because the main traction means 28 and the gap between the through holes 25b, 27c and the insertion holes 26d that accommodate it allow the main traction means 28 to be twisted. The twisted main traction means 28 returns to its original untwisted state with its own shape retaining force when the external force to be twisted is lost.

  The intermediate bending core 27 is fixed with a leading end of a follower pulling means 29 that pulls the intermediate bending core 27 against the straight core 25 and moves the intermediate bending core 27 in the pulling direction from the bent tube 11.

  The follower pulling means 29 is also composed of an appropriate member such as a link mechanism, a cam mechanism, or a chain. In this example, a wire is used.

  That is, two through holes 25c through which the follower pulling means are passed are formed on both sides of the through hole 25b of the straight core 25, and an insertion hole 27d is also formed at a portion corresponding to the through hole 25c in the intermediate bent core 27. The fixed portion 29a formed at the tip of the pulling means 29 is held by the insertion hole 27d.

  At this time, the fixed portion 29a pulls the intermediate bent core 27 when the driven pulling means 29 is pulled, but the intermediate bent core 27 can also be relatively moved rearward (pulling direction) on the driven pulling means 29. A movement allowing portion 27 e is formed in the vicinity of the fixed portion 29 a of the intermediate bending core 27.

  The movement allowance portion 27e can be configured by a hole portion having a large diameter on the tip side. In other words, the fixed portion 29a at the tip of the follower pulling means 29 is constituted by, for example, a short cylindrical pin, and this pin is configured to be movable within a hole as the movement allowing portion 27e. The hole portion 27 e passes through the distal end surface of the intermediate bent core 27.

  The secondary traction means is attached to the curved pipe manufacturing apparatus so that the traction and the traction can be released based on the conditions according to the shape of the curved pipe 11 to be manufactured with the straight core 25 being skewered.

  The follower pulling means 29 made of a wire has a degree of freedom of bending in all directions in which the axis of the inner mold 23 is bent, and bends at a bent portion of the bent tube and extends at a straight portion. Displace. For this reason, when the driven pulling means 29 is pulled, the intermediate bent core 27 is pulled rearward, and the intermediate bent core 27 is pressed against the tip of the straight core 25 located on the rear side thereof. That is, the straight core 25 and the intermediate bent core 27 are constrained so as to be aligned in the axial direction of the inner mold 23. Thus, the straight core 25 and the intermediate bent core 27 are integrated while the traction force is acting. Further, the intermediate bent core 27 is pulled out of the bent tube 11 by the pulling of the follower pulling means 29.

  When the follower pulling means 29 is loosened and the restraint is released and loosened, the straight core 25 and the intermediate bend core 27 can be separated from each other alternately, and the straight core 25 is relatively moved along the longitudinal direction of the follower pulling means 29. Is allowed, and the intermediate bending core 27 is allowed to rotate in the direction in which the axis of the inner mold 23 is twisted. The latter relative rotation is possible because the follower pulling means 29 and the gap between the through hole 25c accommodating the same and the insertion hole 27d allow free twisting of the follower pulling means 29. Two twisted follower pulling means 29 are provided on both sides of the shaft center, so that when the external force to be twisted disappears, the original untwisted state is restored by its own restoring force.

  The inner mold 23 having the main traction means 28 and the secondary traction means 29 has a space between the tip bending core 26, the intermediate bending core 27, and the straight core 25 as indicated by phantom lines in FIGS. 1 and 6. In addition to being separable, as shown by thick arrows in FIG. 1, the tip bending core 26 and the intermediate bending core 27 are mainly free in the bending direction of the bending tube 11 in the direction in which the axis of the inner mold 23 is bent. In the other directions, there is a gap between the main traction means 28 and the secondary traction means 29 and the inner surfaces of the through holes 25b, 25c, 27c and the insertion holes 26d, 27d that accommodate them. Some bending is possible. In addition, due to the gap between the main traction means 28 and the secondary traction means 29 and the periphery thereof, as shown by the thin arrows in FIG. 1, the tip bending core 26 and the intermediate bending core 27 are slightly twisted (the axis of the inner mold 23 is aligned). Displacement in the twisting direction) is allowed.

  In the bent pipe manufacturing apparatus configured as described above, the bent pipe 11 is manufactured by the following method.

  First, a mold clamping process is performed (see FIGS. 8 and 9). The cores 25, 26, and 27 constituting each inner mold 23 are pulled and integrated by pulling the main pulling means 28, and the pair of inner molds 23 are bonded together and covered with the outer mold 22. At this time, the subtraction means 29 may be towed.

  8 to 15, for the convenience of explanation, the bent portion 12 portion of the bent tube 11 and the corresponding mold portion are not twisted.

  Next, an injection process for injecting molten resin into the cavity 24 between the inner mold 23 and the outer mold 22 is performed (see FIGS. 10 and 11).

  Subsequently, a mold opening process is performed through a pressure holding process and a cooling process. The mold opening process includes an outer mold opening process for opening the outer mold 22 (see FIG. 12), and an inner mold removing process for removing the inner mold 23 from the bent tube 11 after the outer mold opening process.

  When manufacturing the bent pipe 11 having the shape as described above, since both of the pair of inner molds 23 have the same shape, any one of the inner molds 23 may be pulled out first. Is straight, or when the curve is more gradual, one of the inner molds 23 may be removed first.

  In the inner die cutting step, first, the relative movement in the drawing direction of the straight core 25 and the traction release of the main traction means 28 and the secondary traction means 29 are performed. As shown by the phantom lines in FIG. 6 when the traction is released, all the cores 25, 26, 27 constituting the inner mold 23 are in a state in which they can be separated. The distance that the straight core 25 is relatively moved in the pulling direction is such that even if the convex portions 25a and 27a and the concave portions 26a and 27b exist, the tip bent core 26 and the intermediate bent core 27 are bent in the axis of the inner mold 23. It is set so that the displacement in the direction of twisting the shaft center of the inner mold 23 is possible.

  13, 14, and 15, the straight core 25, the intermediate bent core 27, and the tip bent core 26 are pulled by the main pulling means 28 and the secondary pulling means 29, The end surface of the bent tube 11 is pushed by the mouth mold 22a that is in contact with the end of the bent tube 11, and is sequentially removed from the core on the end side.

  Specifically, the straight core 25 is pulled back in the pulling direction so that the intermediate bent core 27 can be moved on the main traction means 28 so that a gap can be formed between all the cores 25, 26, 27. At the same time, the follower pulling means 29 is pulled or the end face of the bent tube 11 is pressed by the mouth mold 22a, so that a gap is formed between the straight core 25, the intermediate bent core 27 and the tip bent core 26. to make. Then, all the cores 25, 26, and 27 are sequentially moved in the direction in which the cores 25, 26, and 27 are pulled out from the curved pipe 11 with the gaps therebetween.

  At this time, the straight core 25 comes off by linearly moving in a straight line, and the subsequent intermediate bent core 27 slides along the twisted inner surface of the bent tube 11 and rotates as shown in FIG. As shown in FIG. 14, it is displaced relative to the large-diameter portion 13 of the bent tube 11.

  Since the inner diameter width of the large-diameter portion 13 is wider than that of the bent portion 12, even when the bent core 12 is divided into two, the bent core 12 and the intermediate bent core 27 are placed in an upright posture, depending on the diameter and curvature of the bent portion 12. Can be acceptable. When moving to the large-diameter portion 13, the slight material elasticity of the bent tube 11 becomes a factor that promotes the movement of the bent core core 26 and the intermediate bent core 27. The intermediate bent core 27 that has entered the large-diameter portion 13 is pulled straight out in the drawing direction.

  Further, when the intermediate bending core 27 is displaced, the intermediate bending core 27 is formed with the movement allowing portion 27e. Therefore, the fixed portion of the driven traction means 29 is not required even if the traction means 29 is not always operated properly. The above-mentioned displacement is made while 29a moves appropriately in the movement allowing portion 27e. For this reason, the displacement of the intermediate bending core 27 is performed flexibly along the inner surface of the bending tube 11.

  In synchronism with the movement of the intermediate bent core 27, the bent portion of the bent tube 11 is similarly bent by the pulling of the main pulling means 28 or the pressing of the end surface of the bent tube 11 by the mouth portion mold 22a. 12 is rotated relative to the large-diameter portion 13 of the bent tube 11 while being appropriately rotated, and then is drawn straight in the axial direction.

  The tip bent core 26 and the intermediate bent core 27 are displaced not only in the direction of bending the axis of the inner mold 23 but also in the direction of twisting around the axis of the inner mold 23 as indicated by arrows in FIG. Since a gap is formed between the two, the intermediate bent core 27 and the tip bent core 26 can simultaneously perform their own relative rotation as described above. For this reason, when the cores 25, 26, 27 are pulled out, the bent cores 26, 27 and the bent tube 11 are removed as described above while appropriately displacing them.

  By completing the inner die removing process in this way, as shown in FIG. 15, the removal of the bent tube 11 as the product is completed.

  As described above, in this bent tube manufacturing method and apparatus, the pair of inner molds 23 is constituted by three or more cores 25, 26, and 27, and the bent cores 26 and 27 that form the bent portion 12 of the bent tube 11 are formed. Since two or more are provided, the arcuate contours on the outer sides of the bent cores 26 and 27 may be small relative to the size of the diameter. For this reason, even when each bending core 26 and 27 is in a standing posture, the left and right widths can be made relatively small compared to the size of the diameter. As a result, the bent cores 26 and 27 can be accommodated in the large-diameter portion 13 of the bent tube 11, and the bent tube has a small curvature relative to the size of the diameter like a conventional U-shaped tube. Instead, the bent pipe 11 having a large curvature can be manufactured.

  Moreover, the tip bending core 26 and the intermediate bending core 27 are not only in the direction of bending the axis of the inner mold 23 but also in the direction of twisting around the axis of the inner mold 23 as indicated by arrows in FIG. Since the displacement is possible, the inner mold 23 can be extracted even with the above-described curved pipe 11 (twisted pipe) in which the axial centers of both ends are in a torsional positional relationship.

  For this reason, it becomes possible to manufacture a twisted tube by injection molding, which could not be manufactured conventionally.

  As described above, since the inner die removing step is performed after the outer die 22 is removed, the material elasticity of the bent tube 11 as a molded product can also be used. That is, since the inner mold can be designed in consideration of slight elastic deformation of the curved pipe 11 when the inner mold 23 is pulled out, it is possible to manufacture a curved pipe that seems to be difficult at first glance.

  Further, since a chain is used for the main traction means 28 and a wire is used for the secondary traction means 29, it is possible to easily manufacture a curved pipe that is thinner than when a link mechanism or the like is used. If the main pulling means 28 is also made of a wire, it becomes possible to manufacture a thinner bent pipe.

  Furthermore, since the intermediate bending core 27 is provided with a movement allowing portion 27e that allows the movement of the tip of the follower pulling means 29, the subtraction means 29 does not hinder subtle displacement of the intermediate bend core 27. . For this reason, traction control is easy and an inner die removing process by pressing the end surface of the bent tube 11 by the mouth portion mold 22a is possible.

In correspondence between the configuration of the present invention and the configuration of the one aspect,
The bent portion of the present invention corresponds to the bent portion 12,
Similarly,
The inner base carrier corresponds to the straight core 25,
The inner bending portion carrier corresponds to the tip bending core 26 and the intermediate bending core 27.
The present invention is not limited to the above configuration, and other forms can be adopted.

  For example, as a curved pipe, a curved pipe having a relationship in which the axial centers of both ends are parallel or intersecting like a U-shaped pipe instead of a twisted pipe can be manufactured.

  Further, the pair of inner molds may not have the same shape, and one inner mold may have a shape such as a straight line that is easy to remove.

DESCRIPTION OF SYMBOLS 11 ... Bending pipe 12 ... Bending part 22 ... Outer mold 23 ... Inner mold 24 ... Cavity 25 ... Straight core 26 ... End bending core 27 ... Intermediate bending core 27e ... Movement permission part 28 ... Main traction means 29 ... Subtraction traction means

Claims (3)

An outer mold that can be opened and closed, and an inner mold that is accommodated in the outer mold, a curved pipe-shaped cavity corresponding to a curved pipe having a bent portion is formed, and molding is performed by injecting molten resin into the cavity. After that, a bent pipe manufacturing apparatus for removing the bent pipe as a molded product from the outer mold and the inner mold,
The inner mold bisects the inside of the curved pipe in the longitudinal direction, and includes a pair of inner molds whose tips can be contacted and separated,
Among these inner molds, an inner mold for forming a bent portion of the bent pipe is an inner mold base carrier located on the most end side of the bent pipe,
A plurality of inner-type bent portion carriers for forming a bent portion of the bent tube located on the tip side of the inner-type base carrier;
Of the inner bent portion carriers, the inner bent portion carrier at the tip is constrained and integrated so that the inner mold base carrier and the inner bent portion carrier are aligned in the axial direction of the inner mold by pulling. The main traction means, which can be separated from each other by loosening, are fixed,
The inner bending portion carrier on the end side of the bent tube from the inner bending portion carrier at the tip of the inner bending portion carrier is fixed with a follower pulling means that moves in the pulling direction by pulling.
The bent pipe manufacturing apparatus in which the inner-type bending portion carrier is formed to be displaceable in a direction in which the inner-center axis is bent. The bent pipe manufacturing apparatus according to claim 1 , wherein the inner-type bent portion carrier is formed to be displaceable in a direction in which the inner mold axis is twisted in addition to a direction in which the inner mold axis is bent. In the vicinity of the fixed portion that fixes the inner bending portion carrier to the inner bending portion carrier in the driven traction means, a movement allowing portion that allows the inner bending portion carrier to relatively move in the pulling direction on the driven traction means is formed. The curved pipe manufacturing apparatus according to claim 1 or 2 .

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