Device for manufacturing a tube

Abstract

The present invention provides a pipe body manufacturing apparatus that enables stable molding by preventing molding defects caused by sagging, by causing resin pressed out of a resin discharge port to adhere to the inner wall of a molding block quickly. The pipe body manufacturing apparatus includes: a resin discharge portion (resin discharge port 47) that discharges a cylindrical molten resin into a molding block (36, 38); a shape adjustment portion (shape adjustment jig 50) that expands the diameter of the cylindrical molten resin discharged from the resin discharge portion; and a pressure maintaining portion (pressure maintaining jig 60) that can maintain the internal pressure of the cylindrical molten resin discharged from the resin discharge portion.

Description

TECHNICAL FIELD

[0001] The present application relates to a manufacturing apparatus for a pipe body such as a resin-made inner liner of a high-pressure tank (also referred to as a pressure container or the like), and particularly relates to a manufacturing apparatus for shaping a pipe body by extrusion corrugated tube shaping. BACKGROUND

[0002] As a method for manufacturing such a pipe body, for example, Patent Literature 1 describes a method in which a plurality of molding blocks joined in a band shape are arranged around a core rod, a resin material is extruded toward a mold cavity space formed between the molding blocks and the core rod, and the molding blocks are sequentially fed out to shape a pipe body (a synthetic resin pipe).

[0003] In addition, Patent Literature 2 describes a method in which a step of supplying a corrugated protective layer having a mountain portion and a valley portion on an outer peripheral surface to an extrusion molding portion, and a step of widening the tubular protective layer in the extrusion molding portion in a state in which the protective layer is in contact with a molten resin constituting an outer cover, and extrusion molding the outer cover are performed.

[0004] PRIOR ART DOCUMENTS

[0005] PATENT LITERATURE

[0006] PATENT LITERATURE 1: Japanese Patent Application Laid-Open No. 5-318556

[0007] PATENT LITERATURE 2: Japanese Patent Application Laid-Open No. 2020-140064 SUMMARY

[0008] SUMMARY OF THE INVENTION

[0009] PROBLEMS TO BE SOLVED BY THE INVENTION

[0010] In such extrusion corrugated tube shaping, a cylindrical molten resin pipe (hereinafter, sometimes referred to as a molten resin pipe) extruded from a resin discharge port is sagged (also referred to as dropped) due to the influence of gravity. In particular, in a case where the expansion ratio becomes several times, the distance between the molten resin pipe extruded from the resin discharge port and the molding blocks becomes far, and the upper portion of the molten resin pipe is difficult to contact (stick) to the mold, and it is difficult to follow the contour of the mold. That is, if the diameter of the shaped product is enlarged, the shaped product is sagged due to gravity before solidification, and it can be likely that shaping failure occurs.

[0011] The present application is made in view of the above circumstances, and aims to provide a pipe body manufacturing apparatus which causes the resin extruded from the resin discharge port to quickly stick to the inner wall of the molding blocks, thereby preventing shaping failure due to sagging and enabling stable shaping.

[0012] MEANS FOR SOLVING THE PROBLEMS

[0013] To achieve the foregoing object, a pipe body manufacturing apparatus of the present application is a pipe body manufacturing apparatus that shapes a pipe body into a tubular shape, characterized by comprising: a molding block; a resin ejection section that ejects a tubular molten resin into the molding block and is capable of changing a relative position in an axial direction with respect to the molding block; a shape adjustment section that expands a diameter of the tubular molten resin ejected from the resin ejection section; and a pressure holding section that is capable of holding an internal pressure of the tubular molten resin ejected from the resin ejection section.

[0014] In a preferred aspect, the shape adjustment section includes a gas discharge path that discharges gas in a direction inclined toward a radial outer side inside the tubular molten resin ejected from the resin ejection section.

[0015] In another preferred aspect, the gas discharge path includes a central supply path that extends in the axial direction and a plurality of inclined supply paths that branch from the central supply path in a direction inclined toward a radial outer side and open into the inside of the tubular molten resin ejected from the resin ejection section.

[0016] In another preferred aspect, the shape adjustment section includes a guide surface that guides the tubular molten resin ejected from the resin ejection section toward a radial outer side as it goes downstream.

[0017] In another preferred aspect, the shape adjustment section is provided at an ejection side end portion of the resin ejection section.

[0018] In another preferred aspect, the pressure holding section is composed of a pressure holding clamp that extends in the axial direction inside the molding block.

[0019] In another preferred aspect, the pressure holding section is connected to and held by the shape adjustment section.

[0020] In another preferred aspect, the shape adjustment section includes a gas discharge path that discharges gas in a direction inclined toward a radial outer side inside the tubular molten resin ejected from the resin ejection section, and the pressure holding section is composed of a pressure holding clamp that extends in the axial direction inside the molding block and by being pressed by the pressure of the gas inside a thin diameter portion that is the smallest diameter in the tubular resin of the molding block.

[0021] In another preferred aspect, a clearance area between the thin diameter portion and the pressure holding clamp passing inside the thin diameter portion is smaller than a minimum flow path cross-sectional area of the gas discharge path.

[0022]

Effects of Invention

[0023] According to the present application, when a pipe body is shaped by extrusion corrugation forming, the resin pressed out from the resin ejection portion is quickly attached to the inner wall of the molding block while the inner pressure is applied to the cylindrical molten resin by the pressure holding portion, whereby stable shaping can be performed while preventing shaping failure caused by sagging. BRIEF DESCRIPTION OF DRAWINGS

[0024] Figure 1 is a perspective view schematically showing a manufacturing apparatus of an inner liner (pipe body) of the present embodiment.

[0025] Figure 2 is a longitudinal sectional view showing the manufacturing apparatus of the inner liner (pipe body) of the present embodiment.

[0026] Figure 3 is a longitudinal sectional view showing a main part of the manufacturing apparatus of the inner liner (pipe body) of the present embodiment.

[0027] Figure 4 is a side view of a shape adjusting attachment.

[0028] Figure 5 is Figure 4 A-A line view of

[0029] REFERENCE NUMERALS

[0030] 10 inner liner (pipe body)

[0031] 12 stem portion

[0032] 14 dome portion

[0033] 16 head portion

[0034] 30 manufacturing apparatus

[0035] 32 first outer mold portion

[0036] 34 second outer mold portion

[0037] 36 plurality of molding blocks

[0038] 38 plurality of molding blocks

[0039] 40 spout

[0040] 42 inner mold

[0041] 44 outer mold

[0042] 46 resin supply path 47 resin ejection port (resin ejection portion)

[0043] 48 molten resin pipe

[0044] 49 gas supply path 50 shape adjusting attachment (shape adjusting portion)

[0045] 52 outer peripheral surface (guide surface)

[0046] 54 gas discharge path

[0047] 55 gas supply port 60 pressure holding jig (pressure holding portion)

[0048] P straight line travel region

[0049] R1 first direction (circulation direction of first outer mold portion) R2 second direction (circulation direction of second outer mold portion) DETAILED DESCRIPTION

[0050] Hereinafter, an embodiment of the present application will be described with reference to the drawings.

[0051] First, a resin-made liner (hereinafter, simply referred to as a liner) 10 of a high-pressure tank which is a manufacturing object of the present embodiment will be described, and then a manufacturing apparatus 30 of the liner 10 will be described. Then, a manufacturing method of the liner 10 will be described. Note that, Figures 1-5 The arrow CL which is appropriately shown indicates a central axis of the liner 10. Also, in the case of being simply referred to as an axial direction, a direction along the central axis CL is indicated, and in the case of being referred to as a radial direction, a direction along a radial direction of the liner 10 is indicated.

[0052] (Structure of the liner)

[0053] Figure 1 、 Figure 2 A cross-sectional view of the liner 10 in the middle of molding is shown. The liner 10 of a finished product is also of the same structure in principle, and thus the structure of the liner 10 will be described with reference to these drawings.

[0054] The liner 10 constitutes a pipe body which has a cylindrical shape or a circular ring shape as a whole shape. The liner 10 includes a substantially cylindrical stem portion 12, dome portions 14 which are respectively formed at both axial ends of the stem portion 12 and which gradually narrow (decrease in diameter) as they go toward opposite sides (axially outer sides) of the stem portion 12, and a head portion 16 which is formed at an axial end portion of the dome portion 14 on the opposite side to the stem portion 12 and which is a substantially cylindrical shape with a smaller diameter than the stem portion 12. In the present embodiment, the head portion 16 becomes a thin diameter portion which is the smallest diameter in the liner 10.

[0055] As an example, the liner 10 is a container main body of a high-pressure tank which is used as a hydrogen tank mounted on a fuel cell vehicle, and constitutes an innermost layer of the high-pressure tank. The liner 10 is formed of a resin material (nylon, polyethylene, or the like), and a reinforcing layer (for example, a fiber-reinforced resin layer) which is not shown is formed on an outer peripheral surface thereof to constitute the high-pressure tank.

[0056] The axial end of the head 16 of the liner 10, opposite to the dome 14, is open (not shown), and a plug (not shown) is fitted from this open end. Furthermore, the pressure vessel is sealed by a sealing ring (not shown) that forms part of the plug, which is in close contact with the inner surface 16A of the head 16.

[0057] (Structure of the lining manufacturing apparatus)

[0058] Next, refer to Figures 1-5 This describes the manufacturing apparatus 30 for the liner 10 in this embodiment.

[0059] Figure 1 The overall structure of the manufacturing apparatus 30 for the liner 10 according to this embodiment is schematically shown. As shown in the figure, the manufacturing apparatus 30 for the liner 10 includes a first outer mold portion 32 and a second outer mold portion 34. It should be noted that, although the first outer mold portion 32 and the second outer mold portion 34 are shown as lower halves cut off in the horizontal direction in this figure, the nozzle 40 (outer mold 44), the portion immediately after the molten resin tube 48 is ejected, and the pressure holding clamp 60 are shown as uncut. The first outer mold portion 32 is a track-shaped mold in which a plurality of molding blocks 36 are connected and circulate at a constant speed in the first direction R1. Similarly, the second outer mold portion 34 is a track-shaped mold in which a plurality of molding blocks 38 are connected and circulate at the same speed as the first outer mold portion 32 in the second direction R2, which is the opposite direction to the first direction R1.

[0060] The first outer mold portion 32 and the second outer mold portion 34 are configured such that, within a straight-line travel region P, a portion of their respective travel paths is straight, they travel in a straight line in the same direction while the multiple molding blocks 36 and 38 are in contact with each other, i.e., the mold is closed. Specifically, the first outer mold portion 32 and the second outer mold portion 34 converge at the upstream beginning (hereinafter appropriately referred to as the "beginning") of the travel direction in the straight-line travel region P, and branch off at the downstream end (hereinafter appropriately referred to as the "end") of the travel direction in the straight-line travel region P. It should be noted that... Figure 1 The diagram shows a general overview of the overall structure of the manufacturing apparatus 30, and is not a detailed representation of the individual shapes of the plurality of molding blocks 36 and 38. Therefore, for information regarding the structure of the plurality of molding blocks 36 and 38, please refer to [reference needed]. Figure 2 The following is an explanation.

[0061] like Figure 2 As shown, the plurality of molding blocks 36 of the first outer mold portion 32 and the plurality of molding blocks 38 of the second outer mold portion 34 form the inner liner 10 from the outside. It should be noted that, in Figure 2In the longitudinal sectional view, the sides of the plurality of molding blocks 36 constituting the first outer mold portion 32 are shown, but the plurality of molding blocks 38 constituting the second outer mold portion 34 are also the same as the plurality of molding blocks 36 constituting the first outer mold portion 32. Specifically, the plurality of molding blocks 36 (38) have mold cavities with a generally semi-circular cross-section, including a main body forming portion 22 for forming the main body 12 of the inner liner 10, a dome forming portion 24 for forming the dome 14, and a head forming portion 26 for forming the head 16. The main body forming portion 22 is composed of a semi-cylindrical surface with a relatively large diameter that is long in the axial direction. The dome forming portion 24 is formed at the axial end of the main body forming portion 22 and is composed of a conical surface that gradually narrows in diameter as it moves toward the opposite side of the main body forming portion 22. The head forming portion 26 is formed at the axial end of the dome forming portion 24 and is composed of a semi-cylindrical surface with a relatively small diameter (smaller than the main body forming portion 22). In this embodiment, the head forming portion 26 is the smallest diameter portion. The main body forming part 22, the dome forming part 24 and the head forming part 26 form the forming surfaces (inner surfaces) of multiple molded blocks 36 and 38.

[0062] The straight-line travel region P is the region where shaping takes place; therefore, in this region, such as... Figure 2 As shown, multiple adjacent molded blocks 36 move in a state of mutual contact, and multiple adjacent molded blocks 38 move in a state of mutual contact.

[0063] It should be noted that the size and shape of the multiple molded blocks 36 and 38 are not limited to [specific dimensions]. Figure 2 The example shown is as follows. For instance, the dome 14 and head 16 can be formed by a single molding block 36, 38 (in other words, the junction of the main body 12 and the dome 14, and the junction of the dome 14 and the head 16 can coincide with the junction of multiple molding blocks 36, 38), or the dome 14 and head 16 can be formed by two or more molding blocks 36, 38.

[0064] In addition, the plurality of molding blocks 36 of the first outer mold portion 32 and the plurality of molding blocks 38 of the second outer mold portion 34 have suction openings (not shown) at various locations on their inner surfaces (forming surfaces) for attracting the molten resin tube 48 (described later) for mold transfer.

[0065] return Figure 1 A nozzle 40, which forms part of the extrusion molding machine, is provided in the upstream region of the straight-line travel area P as a resin ejection device. The nozzle 40 includes a generally cylindrical outer mold 44 and a generally cylindrical inner mold 42 (see reference) disposed inside the outer mold 44 (hollow portion) with a smaller diameter than the outer mold 44. Figure 2 , Figure 3 ).

[0066] like Figure 2 ,Figure 3 As shown, the outer mold 44 is concentrically arranged with the inner mold 42 in a state that the front ends (downstream ends) thereof are substantially identical, and the length direction thereof is oriented in the advancing direction of the first outer mold section 32 and the second outer mold section 34 in the straight-line advancing region P. The gap (substantially cylindrical shape) between the outer mold 44 and the inner mold 42 constitutes a resin supply path 46 through which the molten resin heated to a molten state in a not-shown resin supply device passes, and the opening (substantially circular ring shape) formed by the front end (downstream end in the resin supply direction) of the outer mold 44 and the front end (downstream end in the resin supply direction) of the inner mold 42 becomes a resin ejection port (resin ejection section) 47. The molten resin heated to a molten state in the not-shown resin supply device passes through the gap (i.e., the resin supply path 46) between the outer mold 44 and the inner mold 42 from the resin ejection port 47 to be continuously extruded as a substantially cylindrical molten resin tube 48 at a constant speed. At this time, the molten resin tube 48 is a substantially cylindrical resin in an un-solidified state, and the extrusion direction S thereof is substantially identical with the advancing direction of the first outer mold section 32 and the second outer mold section 34 in the straight-line advancing region P. Further, the inside (hollow portion) of the inner mold 42 constitutes a gas supply path 49 (in detail, an upstream portion thereof) through which a gas (as an example, nitrogen) supplied from a not-shown gas pressure application device (also referred to as a gas blowing) passes.

[0067] A shape adjustment attachment (hereinafter, simply referred to as an attachment) 50 as a shape adjustment section is attached to the front end (downstream end or ejection side end) of the inner mold 42 of the nozzle 40.

[0068] The attachment 50 is formed in a stepped cylindrical shape, and an outer peripheral surface 52 thereof constitutes a guide surface that guides the molten resin tube 48 extruded (ejected) from the resin ejection port 47 toward the radially outer side (in other words, the inner surface of the molding block 36, 38) and expands the diameter of the molten resin tube 48.

[0069] If Figure 2 , Figure 3 is seen together with Figure 4 , Figure 5 , it will be understood that the outer peripheral surface (guide surface) 52 of the attachment 50 is constituted by a substantially cylindrical surface that is substantially identical with the outer diameter of the inner mold 42, includes a starting end surface section 52A that extends in the axial direction continuously with the outer peripheral surface of the inner mold 42, a middle flared section 52B that is constituted by a tapered surface or a conical frustum surface that gradually expands (diameter expands) toward the opposite side (downstream side in the resin supply direction) of the inner mold 42 as it goes toward the axial end portion thereof, and a terminal end surface section 52C that is constituted by a substantially cylindrical surface having a larger diameter than the inner mold 42 formed at the axial end portion of the middle flared section 52B on the opposite side of the inner mold 42.

[0070] Accordingly, the molten resin tube 48 extruded (jetted) from the resin jetting port 47 in the extrusion direction S passes over the start end face portion 52A continuous with the resin jetting port 47 (resin supply path 46), is guided by the intermediate flaring portion 52B toward the radial outer side (in other words, toward a direction inclined toward the outer side with respect to the extrusion direction S) as it goes downstream, and its diameter is enlarged (refer to the solid line arrows in the molding block 36, 38). Figure 3

[0071] In addition, as shown in FIG. 2, the gas discharge path 54 is formed in the interior of the attachment 50, and the gas discharge path 54 discharges (introduces) the gas supplied through the interior of the inner mold 42 to the interior of the molten resin tube 48 and enlarges the diameter of the molten resin tube 48 (to the inner surface of the molding block 36, 38). The gas discharge path 54, together with the interior (hollow portion) of the aforementioned inner mold 42, constitutes the gas supply path 49 through which the gas supplied from a not-illustrated gas pressure application device passes. In other words, the gas discharge path 54 constitutes the downstream portion of the gas supply path 49. Figures 2-5

[0072] The aforementioned gas discharge path 54 includes a relatively large-diameter central supply path 54A extending (in a straight line) in the axial direction from the end portion (upstream end portion in the gas supply direction) on the inner mold 42 side, and a plurality of relatively small-diameter inclined supply paths 54B branching from the axial end portion (downstream end portion in the gas supply direction) on the opposite side of the inner mold 42 from the central supply path 54A and extending in a direction inclined toward the radial outer side. In the present embodiment, the inclined supply paths 54B are arranged four in number at 90-degree intervals around (in the circumferential direction) the central supply path 54A. The front ends (end portions on the opposite side of the inner mold 42 (downstream end portions in the gas supply direction)) of the inclined supply paths 54B open to the terminal end face portion 52C (in the illustrated example, in the vicinity of the downstream end portion thereof) of the outer peripheral face (guide face) 52 of the aforementioned attachment 50, and the openings of the front ends (four openings in total in the circumferential direction in the present embodiment) become the gas supply ports 55.

[0073] Accordingly, the gas supplied through the interior of the inner mold 42 passes through the gas discharge path 54 (central supply path 54A, inclined supply paths 54B), is discharged from the gas supply ports 55 in a direction inclined toward the radial outer side (in other words, in a direction inclined toward the outer side with respect to the extrusion direction S) toward the interior of the molten resin tube 48 guided by the outer peripheral face (guide face) 52 of the attachment 50, and the diameter of the molten resin tube 48 is enlarged (refer to the dashed line arrows in the molding block 36, 38). Figure 3

[0074] ​​​Note that the inclined supply path 54B can extend in a direction inclined toward the radially outer side, for example, can be formed substantially in parallel with the intermediate flared portion 52B in the outer peripheral surface (guide surface) 52 of the accessory 50 (in other words, the inclination angle of the inclined supply path 54B can be formed substantially the same as the inclination angle of the intermediate flared portion 52B), or can be formed at a different angle.

[0075] Further, the outer peripheral surface 52 of the accessory 50, the position, shape, size, and the like of the gas discharge path 54 are of course not limited to the illustrated examples.

[0076] A small-diameter fastening portion 51 (provided protruding toward the axial direction) in which an external thread 51A is formed in the outer periphery is formed in the center of the axial end portion on the inner mold 42 side of the accessory 50. The external thread 51A of the fastening portion 51 is screwed with an internal thread 41A of a receiving portion 41 provided in the inner periphery of the inner mold 42, whereby the accessory 50 is mounted and fixed to the front end of the inner mold 42 of the nozzle 40. Note that the mounting structure of the accessory 50 to the nozzle 40 is of course not limited to the illustrated example.

[0077] A stepped small-diameter fastening portion 59 (provided protruding toward the axial direction) in which an external thread 59A is formed in the outer periphery is formed in the center of the axial end portion on the side opposite to the inner mold 42 of the accessory 50. The external thread 59A of this fastening portion 59 is screwed with an internal thread 69A of a receiving portion 69 provided in the inner periphery of a pressure holding jig 60 to be described later, whereby the pressure holding jig 60 as a pressure holding portion is mounted and fixed to the front end (downstream end portion) of the accessory 50.

[0078] The pressure holding jig 60 mounted to the front end of the accessory 50 has a substantially cylindrical shape extending in the axial direction (linearly), is disposed inside the molten resin pipe 48 extruded (jetted) from the resin discharge port 47, and maintains the internal pressure of the molten resin pipe 48 extruded (jetted) from the resin discharge port 47 into the plurality of molded blocks 36, 38, in detail, into the plurality of molded blocks 36, 38.

[0079] The length in the axial direction of the pressure holding jig 60 has a length capable of being inserted through the head portions 16 (in other words, the two head portion forming portions 26 of the plurality of molded blocks 36, 38) formed at both axial ends of the inner liner 10 in the middle of molding. In other words, the length in the axial direction of the pressure holding jig 60 is set to be equal to or greater than the length (interval) in the axial direction of the head portions (small-diameter portions) 16 formed at both axial ends of the inner liner 10 in the middle of molding. Further, the outer diameter of the pressure holding jig 60 is formed to be the same as or slightly smaller than the inner diameter of the head portions 16 (in other words, the molten resin pipe 48 pressed against the two head portion forming portions 26 of the plurality of molded blocks 36, 38) formed at both axial ends of the inner liner 10 in the middle of molding.

[0080] Therefore, the head 16 of the inner liner 10 in the middle of molding into which the pressure retaining jig 60 is inserted narrows (reduces) the cross-sectional area of the pressure retaining jig 60. Therefore, the flow resistance at the head 16 as the thin diameter portion increases, and the gas discharged from the gas supply port 55 to the inside of the molten resin pipe 48 through the gas discharge path 54 (the central supply path 54A, the inclined supply path 54B) is difficult to escape from the head 16 of the inner liner 10 in the middle of molding, and remains in the molten resin pipe 48 in the middle of molding, and the internal pressure of the molten resin pipe 48 is easily maintained.

[0081] In the present embodiment, the (annular) gap area between the pressure retaining jig 60 and the head 16 of the inner liner 10 in the middle of molding (in other words, the molten resin pipe 48 pressed to the two head molding portions 26 of the plurality of molding blocks 36, 38) is set to be the same as or smaller than the minimum flow path cross-sectional area (the minimum value of the flow path cross-sectional area) of the gas discharge path 54 formed in the aforementioned accessory 50. Thus, the amount of gas escaping (discharged) from the (annular) gap between the pressure retaining jig 60 and the head 16 of the inner liner 10 in the middle of molding (in other words, the molten resin pipe 48 pressed to the two head molding portions 26 of the plurality of molding blocks 36, 38) is reliably reduced from the amount of gas discharged (supplied) from the gas supply port 55 through the gas discharge path 54 (the central supply path 54A, the inclined supply path 54B). In other words, the amount of gas discharged from the inside of the molten resin pipe 48 is reliably reduced from the amount of gas supplied to the inside of the molten resin pipe 48. Therefore, the internal pressure of the molten resin pipe 48 is easily and reliably maintained.

[0082] A receiving portion 69 having an internal thread 69A formed in the inner periphery is attached to the vicinity of the axial end portion on the accessory 50 side of the pressure retaining jig 60. The internal thread 69A of the receiving portion 69 is screwed with the external thread 59A of the fastening portion 59 of the aforementioned accessory 50, and thereby the pressure retaining jig 60 is attached and fixed to the front end of the accessory 50. In the present embodiment, the pressure retaining jig 60 is cantilever supported by being connected to the front end of the accessory 50.

[0083] Note that, in the present embodiment, the outer diameter of the pressure retaining jig 60 is formed to be substantially the same as the outer diameter of the accessory 50 (the large diameter portion having the terminal face portion 52C). The pressure retaining jig 60 is attached to the front end of the accessory 50 in a state where the axial end portion on the accessory 50 side abuts against the accessory 50 (the large diameter portion having the terminal face portion 52C). Note that, the attachment structure of the pressure retaining jig 60 to the accessory 50 is of course not limited to the illustrated example.

[0084] (Method for manufacturing inner liner)

[0085] Next, the manufacturing method of the inner liner will be described with reference to the drawings. Figures 1-3The manufacturing method of the liner 10 according to this embodiment will be explained. The liner 10 is manufactured continuously by sequentially performing the following steps.

[0086] First, such as Figure 2 , Figure 3 As shown, molten resin, heated to a molten state in a resin supply device (not shown) located upstream of the linear travel region P, is continuously extruded at a constant speed from the resin outlet 47 as a generally cylindrical molten resin tube 48 through the gap between the outer mold 44 and the inner mold 42 of the nozzle 40 (resin supply path 46). At this time, the molten resin tube 48 is a generally cylindrical resin in an unsolidified state, and its extrusion direction S is approximately the same as the travel direction of the first outer mold portion 32 and the second outer mold portion 34 of the linear travel region P.

[0087] The extruded molten resin tube 48 flows from the initial end portion 52A to the intermediate expansion portion 52B on the outer peripheral surface (guide surface) 52 of the accessory 50 located downstream of the nozzle 40. At this time, guided by the intermediate expansion portion 52B towards the downstream direction and radially outward (in other words, towards the direction inclined outward relative to the extrusion direction S), its diameter gradually increases as it moves towards the downstream side of the straight travel region P (in other words, the downstream side of the resin supply direction).

[0088] The molten resin tube 48, guided by the outer peripheral surface (guide surface) 52 of the attachment 50, is continuously supplied at a constant speed from the upstream side of the straight travel region P to the plurality of molding blocks 36 of the first outer mold 32 and the plurality of molding blocks 38 of the second outer mold 34 in a direction that is radially outward relative to the extrusion direction S, while maintaining an unsolidified state.

[0089] Additionally, simultaneously with the supply of molten resin tube 48, gas supplied by a gas pressure application device (not shown) is supplied to the inside of molten resin tube 48 through a gas supply path 49 (including a gas discharge path 54) inside the inner mold 42 and the accessory 50, via a gas supply port 55 (pressure delivery). At this time, gas is supplied to the inside of molten resin tube 48 in a direction inclined radially outward (in other words, in a direction inclined outward relative to the extrusion direction S) via multiple inclined supply paths 54B of the gas discharge path 54 (pressure delivery). Due to the supply of gas, the gas pressure in the hollow portion of molten resin tube 48 increases, and gas pressure is applied to molten resin tube 48 from the inside, pressing molten resin tube 48 against multiple molding blocks 36 of the first outer mold portion 32 and multiple molding blocks 38 of the second outer mold portion 34 (forming surfaces that form openings for the suction openings used for mold transfer). Furthermore, gas is supplied radially outward to the inside of the molten resin tube 48, thereby applying gas pressure to the molten resin tube 48 from the inside outward (in other words, pressing the molten resin tube 48 radially outward by gas pressure). As a result, the diameter of the molten resin tube 48 gradually increases as it moves downstream of the straight-line travel region P (in other words, downstream of the resin supply direction). The molten resin tube 48 is pressed against the plurality of molding blocks 36 of the first outer mold portion 32 and the plurality of molding blocks 38 of the second outer mold portion 34 (forming surfaces that form openings for the suction openings used for mold transfer).

[0090] Here, without the pressure-holding clamp 60 of this embodiment, the gas supplied to the inside of the molten resin tube 48 is discharged to the outside through the head 16 of the inner liner 10 during the molding process, making it difficult to maintain the gas pressure in the hollow part of the molten resin tube 48.

[0091] In this embodiment, such as Figure 1 , Figure 2 As shown, the pressure-holding clamp 60 held by the attachment 50 is inserted into the head 16 formed at both axial ends of the inner liner 10 during molding. The opening (area) of the head 16 is narrowed (reduced), thus reducing the cross-sectional area of ​​the pressure-holding clamp 60. Therefore, the flow resistance at the head 16, which is a narrow diameter portion, increases, making it difficult for the gas supplied to the inside of the molten resin tube 48 to escape from the head 16 during molding. Instead, the gas remains in the molten resin tube 48 during molding, making it easier to maintain the gas pressure in the hollow portion of the molten resin tube 48 (i.e., improving the pressure-holding effect).

[0092] Here, in order to effectively improve the pressure holding effect, the (annular) gap area between the pressure holding fixture 60 and the head 16 of the inner liner 10 during the molding process (in other words, the molten resin tube 48 of the two head forming parts 26 of the plurality of molding blocks 36, 38) is set to be below the minimum flow path cross-sectional area of ​​the gas release path 54 formed in the attachment 50 as described above.

[0093] By this pressure-keeping effect, the molten resin tube 48 is quickly pressed against the plurality of molding blocks 36 of the first outer mold section 32 and the plurality of molding blocks 38 of the second outer mold section 34 (mold transfer opening-forming opening forming surface of molding).

[0094] Note that, at a plurality of portions of the inner surfaces of the plurality of molding blocks 36, 38, unillustrated suction opening for suction of the molten resin tube 48 for mold transfer is provided. Thus, between the plurality of molding blocks 36 of the first outer mold section 32 and the plurality of molding blocks 38 of the second outer mold section 34, the downstream side of the molten resin tube 48 becomes positive pressure, and the upstream side becomes negative pressure.

[0095] Thus, the inner liner 10 is molded in a substantially cylindrical shape. During this molding process, the first outer mold section 32 and the second outer mold section 34 continuously circulate (i.e., the relative positions of the plurality of molding blocks 36 of the first outer mold section 32 and the plurality of molding blocks 38 of the second outer mold section 34 and the nozzle 40 and the like continuously change), and the molten resin tube 48 is molded and sequentially conveyed from the upstream toward the downstream in the straight-line travel region P.

[0096] The inner liner 10 molded continuously as described above, when pressed against the plurality of molding blocks 36 of the first outer mold section 32 and the plurality of molding blocks 38 of the second outer mold section 34, is solidified by unillustrated cooling units provided to the molding blocks 36, 38, as shown, is conveyed toward the downstream side of the straight-line travel region P, and is cut by unillustrated cutters at the axial end portions (heads 16 between each other) of the respective inner liners 10, to obtain the inner liner 10. Figure 1

[0097] (EFFECTS)

[0098] As described in the above explanation, in extrusion of the corrugated tube, the molten resin tube 48 pressed out from the resin ejection port 47 is affected by gravity and droops. Thus, the upper portion of the molten resin tube 48 is difficult to contact (difficult to adhere) to the mold, and it is difficult to perform conformation along the mold.

[0099] The manufacturing device 30 of the inner liner 10 of the present embodiment is provided with: the molding blocks 36, 38; a resin ejection section (resin ejection port 47) that ejects a cylindrical molten resin into the molding blocks 36, 38, and that is capable of changing the relative position in the axial direction of the molding blocks 36, 38; a shape adjustment section (shape adjustment attachment 50) that expands the diameter of the cylindrical molten resin ejected from the resin ejection section; and a pressure-keeping section (pressure-keeping jig 60) that is capable of keeping the internal pressure of the cylindrical molten resin ejected from the resin ejection section.

[0100] ​Further, the shape adjusting section (shape adjusting attachment 50) includes a gas discharge path 54 that discharges gas in a direction inclined toward the radial outside inside the cylindrical molten resin that is ejected from the resin ejection section (resin ejection port 47), the pressure maintaining section (pressure maintaining jig 60) is constituted by a pressure maintaining jig 60 that extends through inside the smallest diameter thin diameter section of the cylindrical resin of the molding blocks 36, 38 in the axial direction and is pressed by the pressure of the gas on the inside of the smallest diameter thin diameter section of the cylindrical resin of the molding blocks 36, 38.

[0101] Further, the gap area between the thin diameter section and the pressure maintaining jig 60 that passes through the inside of the thin diameter section is below the smallest flow path cross-sectional area of the gas discharge path 54.

[0102] That is, the manufacturing device 30 of the inner liner 10 of the present embodiment, when shaping the inner liner 10 by extrusion bellows shaping, uses the pressure maintaining jig 60 to impart an internal pressure to the inner liner 10 while imparting the shape. The gas (blowing gas) is supplied from the gas pressure application device, and by reducing the gap between the thin diameter section of the shaped inner liner 10 and the pressure maintaining jig 60, the gas (blowing gas) is retained in the inner liner 10 (inside the molten resin tube 48) midway through shaping, and a static pressure is imparted to the inner liner 10 (inside the molten resin tube 48). The molten resin tube 48 that is pressed out from the resin ejection port 47 is adhered to the mold by the internal pressure, and thus stable shaping can be performed.

[0103] Thus, according to the present embodiment, when shaping the pipe body by extrusion bellows shaping, the cylindrical molten resin is imparted an internal pressure while being imparted the shape by the pressure maintaining section (using the pressure maintaining jig 60), and thus the resin that is pressed out from the resin ejection section (resin ejection port 47) is quickly adhered to the inner wall of the molding blocks 36, 38, and thus stable shaping can be performed while preventing shaping failure due to sagging.

[0104] The above describes an embodiment of the present application, but the present application is not limited to the above-described embodiment, and various modifications can be made within the scope of the gist thereof. For example, in the above-described embodiment, an example was shown in which the relative positions of the molding blocks 36, 38 and the pipe nozzle 40 (resin ejection port 47) and the like in the axial direction are changed by moving the plurality of molding blocks 36 of the first outer mold section 32 and the plurality of molding blocks 38 of the second outer mold section 34, but the relative positions of the molding blocks 36, 38 and the pipe nozzle 40 and the like in the axial direction can also be changed by moving the pipe nozzle 40 (resin ejection port 47) and the like.

Claims

1. An apparatus for manufacturing a tubular body shaped in a cylindrical or tubular form, characterized by comprising: a molding block; a resin ejection section configured to eject a molten resin in a cylindrical form into the molding block and to change a relative position in an axial direction with respect to the molding block; a shape adjusting section configured to expand a diameter of the molten resin in a cylindrical form ejected from the resin ejection section; and a pressure maintaining section configured to maintain an internal pressure of the molten resin in a cylindrical form ejected from the resin ejection section.

2. The apparatus for manufacturing a tubular body according to claim 1, characterized in that the gas discharge path includes a central supply path extending in the axial direction and a plurality of inclined supply paths branching from the central supply path in a direction inclined toward the radial outside and opening into the inside of the molten resin in a cylindrical form ejected from the resin ejection section.

3. The apparatus for manufacturing a tubular body according to claim 1, characterized in that the shape adjusting section includes a guide surface configured to guide the molten resin in a cylindrical form ejected from the resin ejection section toward the radial outside as it goes downstream.

4. The apparatus for manufacturing a tubular body according to claim 1, characterized in that the shape adjusting section is provided at an ejection-side end portion of the resin ejection section.

5. The apparatus for manufacturing a tubular body according to claim 1, characterized in that the pressure maintaining section is constituted by a pressure maintaining jig extending in the axial direction inside the molding block through an inside of a small-diameter portion that is a portion of the molten resin in a cylindrical form pressed by the pressure of the gas against the molding block to become a smallest diameter.

6. The apparatus for manufacturing a tubular body according to claim 1, characterized in that a clearance area between the small-diameter portion and the pressure maintaining jig passing through the inside of the small-diameter portion is smaller than a minimum flow passage cross-sectional area of the gas discharge path.

7. The apparatus for manufacturing a tubular body according to claim 1, characterized in that a length of the pressure maintaining jig in the axial direction is larger than an axial-direction interval of the small-diameter portions formed at both axial ends of the tubular body in the middle of the molding.

8. The apparatus for manufacturing a tubular body according to claim 1, characterized in that an outer diameter of the pressure maintaining jig is formed to be a diameter that is the same as or slightly smaller than an inner diameter of the small-diameter portions formed at both axial ends of the tubular body in the middle of the molding.

9. The apparatus for manufacturing a tubular body according to claim 1, characterized in that the pressure maintaining section is constituted by a pressure maintaining jig extending in the axial direction inside the molding block through an inside of a small-diameter portion that is a portion of the molten resin in a cylindrical form pressed by the pressure of the gas against the molding block to become a smallest diameter.

10. The apparatus for manufacturing a tubular body according to claim 1, characterized in that a clearance area between the small-diameter portion and the pressure maintaining jig passing through the inside of the small-diameter portion is smaller than a minimum flow passage cross-sectional area of the gas discharge path.

11. The apparatus for manufacturing a tubular body according to claim 1, characterized in that a length of the pressure maintaining jig in the axial direction is larger than an axial-direction interval of the small-diameter portions formed at both axial ends of the tubular body in the middle of the molding.

12. The apparatus for manufacturing a tubular body according to claim 1, characterized in that an outer diameter of the pressure maintaining jig is formed to be a diameter that is the same as or slightly smaller than an inner diameter of the small-diameter portions formed at both axial ends of the tubular body in the middle of the molding. ​ ​ ​ ​ ​ ​

Images