Manufacturing equipment for resin pipes

Abstract

This invention aims to create a resin pipe manufacturing device that can produce resin pipes with high dimensional accuracy by reducing deformation of the resin pipes. [Solution] The resin pipe manufacturing apparatus 1 is an apparatus for manufacturing resin pipes PT10 by extrusion molding. The resin pipe manufacturing apparatus 1 includes a diameter expansion device 25 that forms an enlarged resin pipe PT2 by expanding the diameter of the tubular material PT1 of the resin pipe PT10, which has been heated at a temperature below the melting point of the resin material constituting the resin pipe PT10, using a mandrel 252; a second take-up machine 27 located downstream TR1 in the transport direction of the diameter expansion device 25 in the manufacturing apparatus 1, which presses the enlarged resin pipe PT2 in its radial direction and sends it down TR1 in the transport direction; and a deformation reduction device 30 located downstream TR1 in the transport direction of the second take-up machine 27, which reduces the amount of deformation of the enlarged resin pipe PT2 in the radial direction due to the pressing of the second take-up machine 27.

Description

Technical Field

[0001] The present invention relates to a manufacturing apparatus for resin tubes manufactured by extrusion molding of resin tubes.

Background Art

[0002] Manufacturing apparatuses for producing biaxially oriented tubes by stretching a tubular material in the axial and circumferential directions are known. For example, Patent Document 1 discloses a production line for continuously producing plastic tubes by such biaxial stretching. In the production line described in Patent Document 1, a tubular material heated within the range of the molecular orientation temperature is expanded in diameter by a mandrel or the like.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] By the way, in the production line described in Patent Document 1, the tubular material is pulled downstream by a take-up device. The take-up device described in Patent Document 1 moves the tubular material in the downstream direction while pressing the opposing portions of the tubular material radially outward by an endless track in order to obtain a pulling force on the tubular material.

[0005] Thus, when the tubular material is pressed during take-up by the take-up device, the tubular material may be deformed. Therefore, it is required to manufacture a resin tube with high dimensional accuracy by reducing such deformation of the resin tube.

[0006] An object of the present invention is to realize a manufacturing apparatus for resin tubes that can manufacture resin tubes with high dimensional accuracy by reducing deformation of the resin tubes.

Means for Solving the Problems

[0007] A resin pipe manufacturing apparatus according to one embodiment of the present invention is an apparatus for manufacturing resin pipes by extrusion molding. The resin pipe manufacturing apparatus comprises: a diameter expansion device that forms a diameter-expanded resin pipe by expanding the tubular material of the resin pipe, which has been heated at a temperature below the melting point of the resin material constituting the resin pipe, using a mandrel; a diameter-expanded take-up machine located downstream of the diameter expansion device in the conveying direction in the manufacturing apparatus, which presses the expanded diameter-expanded resin pipe in its radial direction and feeds it downstream in the conveying direction; and a deformation reduction device located downstream of the diameter-expanded take-up machine in the conveying direction, which reduces the amount of deformation of the diameter-expanded resin pipe in the radial direction due to the pressing of the diameter-expanded take-up machine (first configuration).

[0008] In the above configuration, the enlarged resin pipe, which has been enlarged by the mandrel, is taken up downstream in the conveying direction by an enlarged-pipe take-up machine. When the enlarged resin pipe is taken up by the enlarged-pipe take-up machine, deformation may occur depending on the hardness of the resin material when it is heated. Specifically, when the enlarged-pipe take-up machine presses the enlarged resin pipe radially and sends it downstream in the conveying direction, the enlarged resin pipe deforms radially due to the pressure from the enlarged-pipe take-up machine.

[0009] In the above configuration, a deformation reduction device located downstream of the post-expansion take-up machine in the conveying direction reduces the amount of deformation of the expanded resin pipe in the radial direction caused by the pressing of the post-expansion take-up machine. Therefore, by reducing the deformation of the resin pipe as described above, it is possible to manufacture resin pipes with high dimensional accuracy.

[0010] In the first configuration, the deformation reduction device has a straightening roller that guides the expanded resin pipe downstream in the conveying direction while pressing it radially at a position in the circumferential direction of the expanded resin pipe that is different from the position pressed by the expanded-diameter take-up machine (second configuration).

[0011] In the above configuration, in order to reduce the amount of deformation of the expanded resin pipe that has been deformed radially by pressing by the expanded resin pipe removal machine, the straightening roller can press radially at a position different from the position pressed by the expanded resin pipe removal machine in the circumferential direction.

[0012] This makes it easy to realize a resin pipe manufacturing apparatus that can reduce the amount of deformation of enlarged resin pipes using a simple configuration such as a straightening roller, thereby producing resin pipes with higher dimensional accuracy.

[0013] In the second configuration, the deformation reduction device further comprises a heating device located downstream in the transport direction of the diameter-expanded take-up machine and upstream in the transport direction of the straightening roller, which heats the diameter-expanded resin pipe to a temperature at which the diameter-expanded resin pipe can be deformed, and an auxiliary take-up machine located downstream in the transport direction of the heating device and the straightening roller, or downstream in the transport direction of the diameter-expanded take-up machine and upstream in the transport direction of the heating device and the straightening roller, which presses the diameter-expanded resin pipe in its radial direction and feeds it downstream in the transport direction (third configuration).

[0014] In the above configuration, after heating the expanded resin tube with a heating device until it is deformable, the amount of deformation of the expanded resin tube can be reduced by an auxiliary take-up machine and straightening rollers located downstream of the heating device in the conveying direction. Alternatively, the amount of deformation of the expanded resin tube can be reduced by the auxiliary take-up machine while the shape of the expanded resin tube can be corrected by the heating device and straightening rollers. This makes it possible to further reduce the amount of deformation of the expanded resin tube and manufacture resin tubes with higher dimensional accuracy.

[0015] In the first configuration, the deformation reduction device includes a heating device located downstream of the diameter-expanded take-up machine in the conveying direction, which heats the diameter-expanded resin pipe to a temperature at which the diameter-expanded resin pipe can be deformed, and an auxiliary take-up machine located downstream of the heating device in the conveying direction, which presses the diameter-expanded resin pipe in its radial direction and sends it downstream in the conveying direction (fourth configuration).

[0016] In the above configuration, after the expanded resin tube is heated by the heating device to a state where it can be deformed, the amount of deformation of the expanded resin tube can be reduced by an auxiliary take-up machine located downstream of the heating device in the conveying direction. This further reduces the amount of deformation of the expanded resin tube, making it possible to manufacture resin tubes with higher dimensional accuracy.

[0017] In the first configuration, The deformation reduction device is located downstream of the transport direction of the post-expansion take-up machine and has an auxiliary take-up machine that presses the expanded resin pipe in its radial direction while sending it downstream in the transport direction (fifth configuration).

[0018] In the above configuration, the expanded resin pipe can be taken up not only by the post-expanding take-up machine but also by an auxiliary take-up machine located downstream of the post-expanding take-up machine in the conveying direction. Therefore, the pressing force when taking up the expanded resin pipe can be distributed between the post-expanding take-up machine and the auxiliary take-up machine. This reduces the amount of deformation of the expanded resin pipe caused by the pressing force applied by the post-expanding take-up machine.

[0019] In any one of the third to fifth configurations, the auxiliary take-up machine presses the expanded resin pipe in the radial direction at a position different from the position pressed by the post-expanded take-up machine in the circumferential direction of the expanded resin pipe, while feeding it in the conveying direction (sixth configuration).

[0020] When the post-expansion removal machine presses the expanded resin pipe, the expanded resin pipe undergoes deformation in which the portion not pressed by the post-expansion removal machine bulges. According to the above configuration, the auxiliary removal machine presses the portion not pressed by the post-expansion removal machine. Therefore, the areas of the expanded resin pipe that are prone to deformation can be pressed intensively. As a result, the amount of deformation in the areas of the expanded resin pipe that are prone to deformation can be concentrated and reduced.

[0021] In the first configuration, A heating furnace that is located upstream in the conveyance direction of the diameter-expanding device and heats the tubular material of the resin tube to the molecular orientation temperature of the resin material constituting the resin tube; a wall thickness measuring device that is located downstream in the conveyance direction of the diameter-expanding and taking-up machine and measures the wall thickness at at least a part of the circumferential direction of the diameter-expanded resin tube; and a temperature control device that controls the temperature of the heating furnace according to the position where the wall thickness measuring device measures the wall thickness and the measured wall thickness of the diameter-expanded resin tube. (The seventh configuration).

[0022] In the above configuration, the temperature of the heating furnace can be controlled based on the wall thickness of the diameter-expanded resin tube measured by the wall thickness measuring device downstream in the conveyance direction of the diameter-expanding and taking-up machine. Thereby, when the diameter of the diameter-expanded resin tube is expanded, the deviation of the wall thickness in the circumferential direction of the diameter-expanded resin tube due to the temperature variation can be suppressed. Thereby, a resin tube with higher dimensional accuracy can be manufactured.

[0023] In the seventh configuration, the wall thickness measuring device measures the wall thickness at a plurality of positions in the circumferential direction with respect to the axis of the diameter-expanded resin tube, the heating furnace has a passage through which the resin tube passes and a plurality of heaters arranged in the circumferential direction with respect to the axis of the resin tube passing through the passage, and the temperature control device controls the temperatures of the plurality of heaters according to the wall thicknesses at the plurality of positions measured by the wall thickness measuring device. (The eighth configuration).

[0024] According to the above configuration, when the diameter of the diameter-expanded resin tube is expanded, the deviation of the wall thickness in the circumferential direction of the diameter-expanded resin tube due to the temperature variation can be suppressed more accurately. Thereby, a resin tube with the intended shape can be manufactured accurately.

[0025] In any one of the first to fifth, seventh or eighth configurations, the resin material is polyethylene. (The ninth configuration).

[0026] Polyethylene is a crystalline resin that easily softens with heating. Therefore, a resin pipe made of polyethylene is likely to deform when passing through a heating process. According to the above configuration, even when manufacturing the resin pipe with polyethylene that is likely to deform when passing through a heating process, the amount of deformation can be suppressed.

Effect of the Invention

[0027] A manufacturing apparatus for a resin pipe according to an embodiment of the present invention includes an expanding device that forms an expanded resin pipe by expanding a tubular material of the resin pipe heated at a temperature below the melting point of the resin material constituting the resin pipe by means of a mandrel, an after-expansion take-up machine that is located downstream in the conveying direction of the expanding device in the manufacturing apparatus and feeds out the expanded resin pipe downstream in the conveying direction while pressing the expanded resin pipe in its radial direction, and a deformation reduction device that is located downstream in the conveying direction of the after-expansion take-up machine and reduces the amount of deformation of the expanded resin pipe in the radial direction due to the pressing of the after-expansion take-up machine.

[0028] Thereby, the deformation of the resin pipe can be reduced, so that a resin pipe with high dimensional accuracy can be manufactured.

Brief Description of the Drawings

[0029] [Figure 1] FIG. 1 is a schematic diagram showing a schematic configuration of a manufacturing apparatus for a resin pipe according to Embodiment 1 of the present invention. [Figure 2] FIG. 2 is a schematic enlarged cross-sectional view of a second take-up machine taken along line II-II shown in FIG. 1. [Figure 3] FIG. 3 is a schematic enlarged cross-sectional view of a correction roller taken along line III-III shown in FIG. 1. [[ID=२६]] [Figure 4] FIG. 4 is a schematic enlarged cross-sectional view of a correction roller taken along line IV-IV shown in FIG. 1. [Figure 5] FIG. 5 is a schematic diagram showing a schematic configuration of a manufacturing apparatus for a resin pipe according to Modification 1 of Embodiment 1. [Figure 6] FIG. 6 is a schematic enlarged cross-sectional view of a third take-up machine taken along line VI-VI shown in FIG. 5. [Figure 7]Figure 7 is a schematic diagram showing the general configuration of a resin pipe manufacturing apparatus according to a modified example 2 of Embodiment 1. [Figure 8] Figure 8 is a schematic diagram showing the general configuration of a resin pipe manufacturing apparatus 13 according to a modified example 3 of Embodiment 1. [Figure 9] Figure 9 is a schematic diagram showing the general configuration of the resin pipe manufacturing apparatus according to Embodiment 2. [Figure 10] Figure 10 is a schematic diagram showing the general configuration of the first heating furnace, the wall thickness measuring device, and the temperature control device shown in Figure 9. [Modes for carrying out the invention]

[0030] The following describes each embodiment with reference to the drawings. In each drawing, the same parts are denoted by the same reference numerals, and the description of those parts will not be repeated. Note that the dimensions of the components in each drawing do not faithfully represent the dimensions of the actual components or the dimensional ratios of each component.

[0031] In the following description, the direction in which the resin pipes are conveyed in each manufacturing process by the resin pipe manufacturing equipment 1, 11, 12, and 2 will be referred to as the conveying direction TR. Furthermore, among the devices included in resin pipe manufacturing equipment 1, 11, 12, and 2, the direction in which the resin pipes are extruded by the extruder 21 will also be referred to as the extrusion direction. The extrusion direction is aligned with the conveying direction TR.

[0032] In the diagram below, the arrow UP indicates the upward direction of resin pipe manufacturing equipment 1, 11, 12, and 2. The arrow DN indicates the downward direction of resin pipe manufacturing equipment 1, 11, 12, and 2. The arrow RG indicates the rightward direction of resin pipe manufacturing equipment 1. The arrow LF indicates the leftward direction of resin pipe manufacturing equipment 1, 11, 12, and 2. Note that the left-right direction of resin pipe manufacturing equipment 1 refers to the left-right direction when viewing resin pipe manufacturing equipment 1, 11, 12, and 2 in the transport direction TR from downstream TR1 to upstream TR2.

[0033] Furthermore, in the following explanation, the expressions "fix," "connect," and "attach" (hereinafter referred to as "fixing, etc.") include not only cases where components are directly fixed to each other, but also cases where they are fixed to each other via other components. In other words, in the following explanation, the expressions "fixing, etc." include both direct and indirect fixing of components to each other.

[0034] [Embodiment 1] (Manufacturing equipment for resin pipes) Figure 1 is a schematic diagram showing the general configuration of a resin pipe manufacturing apparatus 1 according to Embodiment 1 of the present invention. Referring to Figure 1, the resin pipe manufacturing apparatus 1 is an apparatus that continuously manufactures resin pipes PT10 by extrusion molding. The resin pipe manufacturing apparatus 1 manufactures biaxially stretched pipes formed by stretching a tubular material PT1 in the circumferential and axial directions. The resin pipes PT10 manufactured by the resin pipe manufacturing apparatus 1 are pipes made of a resin material such as polyethylene pipes.

[0035] The resin pipe manufacturing apparatus 1 includes, in order from upstream TR2 to downstream TR1 in the conveying direction TR, an extruder 21, a first cooling water tank 22, a first take-up machine 23, a first heating furnace 24, a diameter expanding device 25, a second cooling water tank 26, a second take-up machine 27, and a deformation reduction device 30. Each device (21-27, 30) of the resin pipe manufacturing apparatus 1 has a conveying path TT1 that conveys the resin pipe PT10 of each process in the conveying direction TR. The conveying path TT1 of each device (21-27, 30) is aligned with the central axis P of the screw 213 of the extruder 21, which will be described later.

[0036] (Extruder) The extruder 21 includes a hopper 211, a cylinder 212, a screw 213, and a mold 214.

[0037] Thermoplastic resin material and additives for manufacturing the resin pipe PT10 are supplied from the hopper 211 into the cylinder 212. The resin material fed into the extruder 21 is, as described above, for example, polyethylene pellets or chips.

[0038] The cylinder 212 extends in the extrusion direction along the conveying direction TR. A screw 213 is housed inside the cylinder 212. The screw 213 rotates on a central axis P that extends in the extrusion direction, thereby extruding the thermoplastic resin material, which has been heated above its melting point and melted inside the cylinder 212, in the extrusion direction. In the following description, the central axis P of the screw 213 is also referred to as the central axis P of the extruder 21. Furthermore, in each device located downstream TR1 in the conveying direction of the extruder 21, the central axis P of the resin pipe PT10 in each process passing through the conveying path TT1 coincides with the central axis P of the extruder 21.

[0039] The mold 214 is located at the downstream end of the cylinder 212 and screw 213 in the extrusion direction. The resin material extruded by the screw 213 passes through the mold 214 and is formed into a cylindrical shape. The cylindrical tubular material PT1 is extruded from the downstream end of the mold 214 in the extrusion direction.

[0040] (First cooling water tank) The first cooling water tank 22 cools the tubular material PT1 extruded from the mold 214. For cooling the tubular material PT1 as it passes through the first cooling water tank 22, water is used as a refrigerant, for example. A known cooling device can be used in the first cooling water tank 22.

[0041] (First collection machine) The first take-up machine 23 pulls the tubular material PT1 in the transport direction TR at a position TR1 downstream of the first cooling water tank 22 in the transport direction. The first take-up machine 23 then sends the tubular material PT1 further downstream TR1 in the transport direction. A known take-up machine can be used for the first take-up machine 23.

[0042] (1st heating furnace) The first heating furnace 24 heats the tubular material PT1 that is delivered from the first take-up machine 23 and passes through the first heating furnace 24 in the transport direction TR. Specifically, the first heating furnace 24 heats the tubular material PT1 to a temperature below the melting point of the resin material constituting the resin tube PT10. The heating temperature of the first heating furnace 24 can be set to a temperature above the glass transition temperature and a temperature that allows molecular orientation of the tubular material PT1 by the diameter expansion described later. For example, the first heating furnace 24 may be heated to a temperature within the range of the Vicat softening temperature. The first heating furnace 24 may have a heating device such as a ceramic heater or an electric heating wire. When the tubular material PT1 is polyethylene, the heating temperature of the first heating furnace 24 may be in a range that does not exceed the melting point, for example, from 100°C to 130°C, although the melting point may vary depending on the compound.

[0043] (Diameter expansion device) The diameter expanding device 25 comprises a support 251 and a mandrel 252. The support 251 extends coaxially with the central axis P of the extruder 21 in the transport direction TR.

[0044] The downstream end of the support 251 in the transport direction TR is fixed to the extruder 21. The upstream end of the support 251 in the transport direction TR supports the mandrel 252. The support 251 may also have a heating mechanism, which allows the inner surface of the tubular material PT1 to be heated.

[0045] The mandrel 252 is, for example, a frustoconical shape in which the diameter increases from the upstream TR2 to the downstream TR1 in the conveying direction TR. The mandrel 252 may have rollers, protrusions, or recesses. The tubular material PT1 is pulled in the conveying direction TR by the second take-up machine 27, which will be described later. As the tubular material PT1 passes through the mandrel 252 in the conveying direction TR, it is stretched in the circumferential direction and expanded in diameter, as well as stretched in the axial direction. The tubular material PT1 expanded by the mandrel 252 is conveyed to the second cooling water tank 26 located at TR1 downstream in the conveying direction of the diameter expansion device 25. The expanded tubular material PT1 will be referred to as the expanded resin pipe PT2 below.

[0046] (Second cooling water tank) The second cooling water tank 26 cools the enlarged resin pipe PT2 that has been enlarged by the diameter enlargement device 25. The second cooling water tank 26 has nozzles 261 for injecting cooling water. The nozzles 261 are arranged around the transport path TT1 of the enlarged resin pipe PT2. The nozzle openings of the nozzles 261 are directed towards the transport path TT1 of the enlarged resin pipe PT2. In the second cooling water tank 26, the enlarged resin pipe PT2 is cooled by injecting cooling water from the nozzles 261 arranged around the enlarged resin pipe PT2 onto its outer surface.

[0047] (Second collection machine) The second take-up machine 27 pulls the expanded diameter resin pipe PT2 in the transport direction TR at a position TR1 downstream in the transport direction of the second cooling water tank 26.

[0048] Figure 2 is a schematic enlarged cross-sectional view of the second take-up machine 27 along the line II-II shown in Figure 1. Note that Figure 2 is shown at a larger magnification than Figures 3 and 4, which will be described later, for clarity. Referring to Figure 2 in addition to Figure 1, the second take-up machine 27 has chucks 271, 272, 273, and 274 that press the enlarged resin pipe PT2 in its radial direction and further feed the enlarged resin pipe PT2 downstream TR1 in the transport direction.

[0049] Chucks 271, 272, 273, and 274 are driven by continuous tracks. Chucks 271, 272, 273, and 274 are positioned above, below, to the left, and to the right of the transport path TT1 when viewed in the transport direction TR.

[0050] Chucks 271, 272, 273, and 274 each have a recess 270 that extends radially outward from the radially inner surface along the outer surface of the enlarged resin pipe PT2 passing through the transport path TT1. Chucks 271 and 272, which face each other in the vertical direction, are separated by a specified outer diameter D1 of the resin pipe PT10 at their center in the horizontal direction. Similarly, chucks 273 and 274, which face each other in the horizontal direction, are separated by a specified outer diameter D1 of the resin pipe PT10 at their center in the vertical direction.

[0051] Chucks 271, 272, 273, and 274 grip the expanded diameter resin pipe PT2 by pressing its outer surface radially inward in the up, down, left, and right directions, as shown by the solid white arrows in Figure 2, as the pipe passes through the transport path TT1. This prevents the expanded diameter resin pipe PT2 from slipping against the chucks 271, 272, 273, and 274 during transport.

[0052] As described above, with the expanded diameter resin tube PT2 being held, the chucks 271, 272, 273, and 274 move in the transport direction TR, causing the expanded diameter resin tube PT2 to move in the transport direction TR.

[0053] The second collection machine 27 can also use a known collection machine, similar to the first collection machine 23. The second collection machine 27 can also be of the same type as the first collection machine 23. If the first collection machine 23 is of the same type as the second collection machine 27, the chuck of the first collection machine 23 may be located in the center of the resin pipe PT10 in the vertical direction, or it may be located at a 45-degree inclination with respect to the vertical, horizontal, and vertical directions of the resin pipe PT10.

[0054] (Deformation reduction device) The deformation reduction device 30 is located downstream TR1 in the transport direction of the second take-up machine 27. The deformation reduction device 30 reduces the amount of radial deformation of the expanded resin pipe PT2 caused by the pressing of the second take-up machine 27. The deformation reduction device 30 has, in order from upstream to downstream in the transport direction TR, a second heating furnace 31, a straightening roller 32, and a third take-up machine 33.

[0055] (Second heating furnace) The second heating furnace 31 heats the expanded diameter resin pipe PT2 that is delivered from the second take-up machine 27 and passes through the second heating furnace 31 in the transport direction TR. Specifically, the second heating furnace 31 heats the expanded diameter resin pipe PT2 at a temperature lower than the heating temperature in the first heating furnace 24 but higher than room temperature. The heating temperature in the second heating furnace 31 may be, for example, 35°C to 55°C if the expanded diameter resin pipe PT2 is polyethylene.

[0056] (Corrective roller) The straightening roller 32 straightens the enlarged diameter resin pipe PT2 as it passes through the transport path TT1 within the straightening roller 32 in the transport direction TR. Figure 3 is a schematic enlarged cross-sectional view of the straightening roller 32 along the line III-III shown in Figure 1. Figure 4 is a schematic enlarged cross-sectional view of the straightening roller 32 along the line IV-IV shown in Figure 1.

[0057] Referring to Figures 1, 3, and 4, the straightening roller 32 includes a support plate 320, roller sections 321, 322, 323, and 324, a support plate 325, and auxiliary roller sections 326 and 327.

[0058] The roller sections 321, 322, 323, and 324 are supported by a support plate 320 located upstream TR2 in the conveying direction of the straightening roller 32.

[0059] The roller sections 321, 322, 323, and 324 are each located around the transport path TT1 when viewed in the transport direction TR. The roller sections 321 and 322 are located on an inclined line L3 that extends at a 45-degree angle to one side with respect to a horizontal line L1 passing through the central axis P when viewed in the transport direction TR. The roller sections 323 and 324 are located on an inclined line L4 that extends at a 45-degree angle to one side with respect to a vertical line L2 passing through the central axis P when viewed in the transport direction TR.

[0060] Each of the roller sections 321, 322, 323, and 324 has a roller holding section 3201 and a roller 3202.

[0061] The roller holding section 3201 supports the roller 3202 with respect to the support plate 320.

[0062] The roller 3202 is supported by the roller holding portion 3201 so as to be rotatable around the rotation axis P32. The rotation axis P32 in the roller portions 321 and 322 is perpendicular to the inclined line L3. The rotation axis P32 in the roller portions 323 and 324 is perpendicular to the inclined line L4.

[0063] Each roller 3202 of roller sections 321 and 322 is separated from each other by the specified outer diameter D1 of the resin pipe PT10 at the center in the direction of the rotation axis P32.

[0064] Each roller 3202 of roller sections 323 and 324 is separated from each other by the specified outer diameter D1 of the resin pipe PT10 at the center in the direction of the rotation axis P32.

[0065] The auxiliary roller sections 326 and 327 are supported by a support plate 325 located downstream TR1 in the conveying direction of the straightening roller 32. The auxiliary roller sections 326 and 327 are located on the inclined line L4 when viewed in the conveying direction TR.

[0066] (Third pickup machine) The third take-up machine 33 pulls the expanded diameter resin pipe PT2 in the conveying direction TR at a position TR1 downstream of the straightening roller 32 in the conveying direction. The third take-up machine 33 presses the expanded diameter resin pipe PT2 in its radial direction and further feeds the expanded diameter resin pipe PT2 downstream TR1 in the conveying direction. Similar to the second take-up machine 27, a known take-up machine can be used for the third take-up machine 33. The same type of take-up machine as the second take-up machine 27 can also be used for the third take-up machine 33.

[0067] As described above, the resin pipe manufacturing apparatus 1 includes a diameter expansion device 25 that forms an enlarged resin pipe PT2 by expanding the diameter of the tubular material PT1 of the resin pipe PT10, which has been heated at a temperature below the melting point of the resin material constituting the resin pipe PT10, using a mandrel 252; a second take-up machine 27 located downstream TR1 in the transport direction of the diameter expansion device 25, which serves as a post-expansion take-up machine that presses the enlarged resin pipe PT2 in its radial direction and sends it down TR1 in the transport direction; and a deformation reduction device 30 located downstream TR1 in the transport direction of the second take-up machine 27, which reduces the amount of deformation of the enlarged resin pipe PT2 in the radial direction caused by the pressing of the second take-up machine 27.

[0068] In the above configuration, the expanded resin pipe PT2, expanded by the mandrel 252 of the expansion device 25, is taken up by the second take-up machine 27 at TR1 downstream in the conveying direction. When the expanded resin pipe PT2 is taken up by the second take-up machine 27, deformation may occur depending on the hardness of the resin material when it is heated in the first heating furnace 24. Specifically, when the second take-up machine 27 presses the expanded resin pipe PT2 radially and sends it to TR1 downstream in the conveying direction, the expanded resin pipe PT2 may deform radially due to the pressure from the second take-up machine 27.

[0069] More specifically, referring again to Figure 2, in the second take-up machine 27, the expanded diameter resin pipe PT2 is pressed from the top, bottom, left, and right directions by chucks 271, 272, 273, and 274. As a result, the expanded diameter resin pipe PT2 bulges out from between chuck 271 and chucks 273 and 274, respectively, and from between chuck 272 and chucks 273 and 274, respectively. In Figure 2, the direction of bulging is indicated by dashed-dotted arrows, and the shape of the partially bulged expanded diameter resin pipe PT2 is indicated by dashed-dotted lines.

[0070] In the configuration described above, the deformation reduction device 30 reduces the amount of deformation of the radially expanding resin pipe PT2 caused by the pressing of the second take-up machine 27 at TR1 downstream in the transport direction.

[0071] More specifically, referring again to Figure 3, in the straightening roller 32, the enlarged diameter resin pipe PT2, which is partially bulging, passes between the opposing rollers 3202, which are spaced apart by the specified outer diameter D1 of the resin pipe PT10. This reduces the amount of deformation of the bulging portion.

[0072] Therefore, by reducing the deformation of the resin tube PT10 as described above, it is possible to manufacture resin tube PT10 with high dimensional accuracy.

[0073] Furthermore, in the above configuration, the circumferential positions of the chucks 271, 272, 273, and 274 of the second take-up machine 27 are different from the circumferential positions of the roller 3202 of the straightening roller 32. Therefore, in order to reduce the amount of deformation of the expanded diameter resin pipe PT2 which is deformed radially by the pressing of the second take-up machine 27, the straightening roller 32 can press radially at a position in the circumferential direction that is different from the position pressed by the second take-up machine 27.

[0074] This makes it easy to realize a resin pipe manufacturing apparatus 1 that can reduce the amount of deformation of the enlarged resin pipe PT2 using a simple configuration such as a straightening roller 32, thereby producing a resin pipe PT10 with higher dimensional accuracy.

[0075] In the above configuration, the deformation reduction device 30 includes a second heating furnace 31 as a heating device and a third take-up machine 33 as an auxiliary take-up machine.

[0076] The second heating furnace 31 is located downstream TR1 in the conveying direction from the second take-up machine 27, and upstream TR2 in the conveying direction from the straightening roller 32. The second heating furnace 31 heats the expanded diameter resin pipe PT2 to a temperature at which the expanded diameter resin pipe PT2 can be deformed.

[0077] The third take-up machine 33 is located downstream TR1 in the transport direction of the second heating furnace 31 and also downstream TR1 in the transport direction of the straightening roller 32. The third take-up machine 33 presses the expanded diameter resin pipe PT2 in its radial direction and feeds it to the downstream TR1 in the transport direction.

[0078] In the above configuration, after the second heating furnace 31 heats the expanded resin pipe PT2 to a deformable state, the amount of deformation of the expanded resin pipe PT2 can be reduced by the straightening roller 32 and the third take-up machine 33 located downstream TR1 in the conveying direction of the second heating furnace 31. As a result, the amount of deformation of the expanded resin pipe PT2 can be further reduced, and a resin pipe PT10 with higher dimensional accuracy can be manufactured.

[0079] Furthermore, in the above configuration, the third pull-up machine 33, acting as an auxiliary pull-up machine, presses the expanded diameter resin pipe PT2 in the radial direction at a position different from the point pressed by the second pull-up machine 27 in the circumferential direction of the expanded diameter resin pipe PT2, and then feeds it in the transport direction TR.

[0080] As described above, when the second pull-up machine 27 presses the expanded resin pipe PT2, deformation occurs in the expanded resin pipe PT2 such that the parts not pressed by the second pull-up machine 27 bulge. With the above configuration, the third pull-up machine 33 presses the parts not pressed by the second pull-up machine 27. Therefore, it is possible to concentrate the pressure on the parts of the expanded resin pipe PT2 that are prone to deformation. This makes it possible to concentrate the amount of deformation in the parts of the expanded resin pipe PT2 that are prone to deformation.

[0081] [Modification 1 of Embodiment 1] Figure 5 is a schematic diagram showing the general configuration of the resin pipe manufacturing apparatus 11 according to Modification 1 of Embodiment 1. Figure 6 is a schematic enlarged cross-sectional view of the third take-up machine 43 along the line VI-VI shown in Figure 5. As with the resin pipe manufacturing apparatus 11 according to Modification 1 of Embodiment 1, the deformation reduction device 40 does not necessarily have to have the straightening roller 32. In the following description of Modification 1 of Embodiment 1, parts common to the resin pipe manufacturing apparatus 1 according to Embodiment 1 will be denoted by the same reference numerals and detailed descriptions will not be repeated.

[0082] The resin pipe manufacturing apparatus 11 includes, in order from upstream TR2 to downstream TR1 in the conveying direction TR, an extruder 21, a first cooling water tank 22, a first take-up machine 23, a first heating furnace 24, a diameter expanding device 25, a second cooling water tank 26, a second take-up machine 27, and a deformation reduction device 40.

[0083] The deformation reduction device 40 includes a second heating furnace 31 as a heating device and a third take-up machine 43 as an auxiliary take-up machine.

[0084] The third take-up machine 43 has chucks 431, 432, 433, and 434 that press the expanded diameter resin pipe PT2 in its radial direction and further feed the expanded diameter resin pipe PT2 downstream in the conveying direction TR1.

[0085] Chucks 431, 432, 433, and 434 are each located around the transport path TT1 when viewed in the transport direction TR. Chucks 431 and 432 are located on an inclined line L3 that extends at a 45-degree angle to one side with respect to a horizontal line L1 passing through the central axis P when viewed in the transport direction TR. Chucks 433 and 434 are located on an inclined line L4 that extends at a 45-degree angle to one side with respect to a vertical line L2 passing through the central axis P when viewed in the transport direction TR.

[0086] Chucks 431, 432, 433, and 434 each have a recess 430 that is recessed radially outward from the radially inner surface along the outer surface of the enlarged diameter resin tube PT2.

[0087] Chucks 431 and 432 are separated from each other by the specified outer diameter D1 of the resin pipe PT10 along the inclined line L3.

[0088] Chucks 433 and 434 are separated from each other by the specified outer diameter D1 of the resin pipe PT10 along the inclined line L4.

[0089] In the above configuration, the second heating furnace 31 heats the expanded resin pipe PT2 to a state where it can be deformed, and then the third take-up machine 43, located downstream TR1 in the transport direction of the second heating furnace 31, takes the expanded resin pipe PT2 to TR1 downstream in the transport direction.

[0090] As described above, the third take-up machine 43, which is equipped with chucks 431, 432, 433, and 434, can press the expanded diameter resin pipe PT2 in the radial direction at a position different in the circumferential direction from the position pressed by the second take-up machine 27, and send it to the downstream TR1 in the transport direction.

[0091] This reduces the amount of deformation of the expanded diameter resin tube PT2. Therefore, it is possible to further reduce the amount of deformation of the expanded diameter resin tube PT2 and manufacture a resin tube PT10 with higher dimensional accuracy.

[0092] [Modification 2 of Embodiment 1] Figure 7 is a schematic diagram showing the general configuration of a resin pipe manufacturing apparatus 12 according to Modification 2 of Embodiment 1. As in the resin pipe manufacturing apparatus 12 according to Modification 2 of Embodiment 1, the deformation reduction device 50 does not necessarily have a second heating furnace 31. In the following description of Modification 2 of Embodiment 1, parts common to the resin pipe manufacturing apparatus 11 according to Modification 1 of Embodiment 1 are denoted by the same reference numerals and detailed descriptions are not repeated.

[0093] The resin pipe manufacturing apparatus 12 includes, in order from upstream to downstream in the conveying direction TR, an extruder 21, a first cooling water tank 22, a first take-up machine 23, a first heating furnace 24, a diameter expanding device 25, a second cooling water tank 26, a second take-up machine 27, and a deformation reduction device 50. The deformation reduction device 50 has a third take-up machine 43 as an auxiliary take-up machine.

[0094] In the above configuration, the expanded diameter resin pipe PT2 can be taken up not only by the second take-up machine 27, but also by the third take-up machine 43 located downstream TR1 in the transport direction of the second take-up machine 27. Therefore, the pressing force when taking up the expanded diameter resin pipe PT2 can be distributed between the second take-up machine 27 and the third take-up machine 43. In other words, in the above configuration, the pressing force per take-up machine can be reduced. As a result, even if the pressing force applied by the second take-up machine 27 to the expanded diameter resin pipe PT2 is reduced, the expanded diameter resin pipe PT2 can be prevented from slipping and taken up to TR1 downstream in the transport direction.

[0095] Therefore, the amount of deformation of the expanded resin pipe PT2 due to the pressing force applied by the second take-up machine 27 can be reduced.

[0096] [Modification 3 of Embodiment 1] Figure 8 is a schematic diagram showing the general configuration of a resin pipe manufacturing apparatus 13 according to Modification 3 of Embodiment 1. The deformation reduction device 60 of the resin pipe manufacturing apparatus 13 according to Modification 3 of Embodiment 1 differs from that of Embodiment 1 in the arrangement order of the deformation reduction device 30, the second heating furnace 31, the straightening roller 32, and the third take-up machine 33. In the following description of Modification 3 of Embodiment 1, parts common to the resin pipe manufacturing apparatus 1 according to Embodiment 1 are denoted by the same reference numerals and detailed descriptions are not repeated.

[0097] The resin pipe manufacturing apparatus 13 includes, in order from upstream to downstream in the conveying direction TR, an extruder 21, a first cooling water tank 22, a first take-up machine 23, a first heating furnace 24, a diameter expanding device 25, a second cooling water tank 26, a second take-up machine 27, and a deformation reduction device 60. The deformation reduction device 30 includes, in order from upstream to downstream in the conveying direction TR, a third take-up machine 33, a second heating furnace 31, and a straightening roller 32.

[0098] In the configuration described above, the third take-up machine 33 is located downstream TR1 in the conveying direction of the second take-up machine 27. Therefore, the deformation of the expanded resin pipe PT2 can be reduced by the third take-up machine 33 acting as an auxiliary take-up machine. In addition, the shape of the expanded resin pipe PT2 can be corrected by the straightening roller 32 located downstream TR1 in the conveying direction of the second heating furnace 31.

[0099] [Embodiment 2] Figure 9 is a schematic diagram showing the general configuration of the resin pipe manufacturing apparatus 2 according to Embodiment 2. Figure 10 is a schematic diagram showing the general configuration of the first heating furnace 241, the wall thickness measuring device 51, and the temperature control device 52 shown in Figure 9. Figure 9 shows the first heating furnace 241 and the wall thickness measuring device 51 as viewed upstream TR2 in the conveying direction.

[0100] The resin pipe manufacturing apparatus 2 according to Embodiment 2 differs from the resin pipe manufacturing apparatus 1 according to Embodiment 1 in that it controls the temperature of the first heating furnace 241 according to the wall thickness of the enlarged resin pipe PT2. In the following description of Embodiment 2, parts common to the resin pipe manufacturing apparatus 1 according to Embodiment 1 are denoted by the same reference numerals and detailed descriptions are not repeated.

[0101] (Schematic configuration) Referring to Figure 9, the resin pipe manufacturing apparatus 2 includes, in order from upstream to downstream in the conveying direction TR, an extruder 21, a first cooling water tank 22, a first take-up machine 23, a first heating furnace 241 as a heating device, a diameter expanding device 25, a second cooling water tank 26, a second take-up machine 27, a wall thickness measuring device 51, and a deformation reduction device 30. The resin pipe manufacturing apparatus 2 also includes a temperature control device 52.

[0102] Referring to Figure 10, the first heating furnace 241 has 12 heaters HT1 to HT12 and a temperature controller 2410. Viewed in the transport direction TR, the heaters HT1 to HT12 are positioned in order at 30-degree intervals in the circumferential direction of the tubular material PT1. The temperature controller 2410 is connected to a temperature control device 52, described later, in a signal transmission and reception manner.

[0103] The wall thickness measuring device 51 has 12 wall thickness measuring sensors TK1 to TK12. Viewed in the transport direction TR, the wall thickness measuring sensors TK1 to TK12 are positioned sequentially at 30-degree intervals in the circumferential direction of the enlarged diameter resin pipe PT2. Therefore, the circumferential positions of the wall thickness measuring sensors TK1 to TK12 correspond to the circumferential positions of the heaters HT1 to HT12 of the first heating furnace 241.

[0104] The wall thickness measuring sensors TK1 to TK12 measure the thickness of the enlarged diameter resin tube PT2 at a total of 12 locations. The wall thickness measuring sensors TK1 to TK12 can be configured, for example, by ultrasonic thickness gauges. Based on the measurement results of the wall thickness measuring sensors TK1 to TK12, the wall thickness measuring device 51 generates a tube thickness signal indicating the thickness of the enlarged diameter resin tube PT2 at each measurement location and outputs it to the temperature control device 52.

[0105] The temperature control device 52 is connected to the wall thickness measuring device 51 so as to be able to send and receive signals. Based on the pipe thickness signal output by the wall thickness measuring device 51, the temperature control device 52 generates a temperature command to control the heating temperature of the first heating furnace 241.

[0106] (Temperature control process) The temperature control device 52 calculates, for example, the average value of the pipe thickness at 12 locations and the deviation from the average value of the pipe pressure at each of the 12 locations, based on the pipe thickness signal output by the wall thickness measuring device 51.

[0107] The temperature control device 52 determines whether the deviation from the average value is within an acceptable limit. The temperature control device 52 generates a temperature command to control the heating temperature to increase at locations where the thickness exceeds the allowable limit compared to the average value. The temperature control device 52 generates a temperature command to control the heating temperature to decrease at locations where the thickness exceeds the allowable limit compared to the average value.

[0108] Furthermore, the temperature control device 52 may estimate the heating temperature based on the measurement results using a trained model that has been machine-learned using data including the heating position, heating temperature, thickness measurement position, and thickness measurement results. In addition, the temperature control device 52 may limit the range of vertical fluctuations in the heating temperature at predetermined time intervals. This can prevent extreme temperature fluctuations.

[0109] The temperature control device 52 outputs the generated temperature command to the temperature controller 2410.

[0110] The temperature controller 2410 raises or lowers the temperature of heaters HT1 to HT12 based on a temperature command.

[0111] As described above, the resin pipe manufacturing apparatus 2 includes a first heating furnace 241 located upstream TR2 in the conveying direction of the diameter expanding device 25, which heats the tubular material PT1 of the resin pipe PT10 at a temperature below the melting point of the resin material constituting the resin pipe PT10; a wall thickness measuring device 51 located downstream TR1 in the conveying direction of the second take-up machine 27, which acts as a take-up machine after diameter expansion, which measures the wall thickness at at least a portion of the circumferential position of the expanded resin pipe PT2; and a temperature control device 52 that controls the temperature of the first heating furnace 241 according to the position where the wall thickness measuring device 51 measures the wall thickness and the measured wall thickness of the expanded resin pipe PT2.

[0112] In the above configuration, the wall thickness of the expanded resin pipe PT2 can be measured by the wall thickness measuring device 51 without having to cut the expanded resin pipe PT2 to check its thickness. Furthermore, in the above configuration, the temperature of the first heating furnace 241 can be controlled at TR1 downstream in the transport direction of the second take-up machine 27 based on the wall thickness of the expanded resin pipe PT2 measured by the wall thickness measuring device 51. This makes it possible to suppress unevenness in the circumferential wall thickness of the expanded resin pipe PT2 due to temperature variations during the expansion of the expanded resin pipe PT2.

[0113] For example, in areas where the wall thickness is thin after expansion, lowering the heating temperature can prevent excessive stretching during expansion. Conversely, in areas where the wall thickness is thick after expansion, increasing the heating temperature can facilitate stretching during expansion. This allows for the manufacture of PT10 resin pipes with higher dimensional accuracy. Furthermore, PE pipes experience greater dimensional changes due to temperature fluctuations than PVC pipes. Therefore, the above configuration allows for higher dimensional accuracy in the manufacture of PE pipes.

[0114] Furthermore, the temperature control device 52 controls the temperature of 12 heaters based on the results of measuring the wall thickness at 12 locations in the circumferential direction with respect to the central axis P of the expanded diameter resin tube PT2. This makes it possible to more accurately suppress the unevenness of the circumferential wall thickness of the expanded diameter resin tube PT2 due to temperature variations.

[0115] (Other embodiments) Although embodiments of the present invention have been described above, the embodiments described above are merely examples for carrying out the present invention. Therefore, the invention is not limited to the embodiments described above, and it is possible to carry out the invention by appropriately modifying the embodiments described above without departing from the spirit of the invention.

[0116] In each of the above embodiments, the tubular material PT1 is expanded in diameter by stretching it circumferentially with the mandrel 252, and also stretched in the axial direction. That is, the resin pipe manufacturing apparatus manufactures resin pipes by biaxial stretching. However, the resin pipe manufacturing apparatus does not necessarily have to stretch the tubular material in the axial direction with the mandrel.

[0117] In each of the above embodiments, the chucks of the first take-up machine 23, the second take-up machine 27, or the third take-up machines 33, 43 are located in the vertical center of the resin pipe PT10, or are located at a 45-degree inclination with respect to the vertical, horizontal, and vertical directions of the resin pipe PT10. However, the chucks of the first take-up machine, the second take-up machine, and the third take-up machine may be located at different positions in the circumferential direction of the resin pipe. Furthermore, the chucks of the first take-up machine, the second take-up machine, and the third take-up machine may be located at the same position in the circumferential direction of the resin pipe, or at different positions.

[0118] In each of the above embodiments, the chucks 271, 272, 273, and 274 of the second take-up machine 27 are positioned in the vertical, horizontal, and vertical directions with respect to the transport path TT1, while the roller sections 321, 322, 323, and 324 of the straightening roller 32 are positioned at a 45-degree inclination with respect to the vertical, horizontal, and vertical directions. However, the four roller sections of the straightening roller may be positioned in the vertical, horizontal, and vertical directions, and the chucks of the second take-up machine may be positioned at a 45-degree inclination with respect to the vertical, horizontal, and vertical directions.

[0119] In the embodiments 1 and 2 described above, the straightening roller 32 has four roller sections 321, 322, 323, and 324. However, the straightening roller may have one or more pairs of roller sections that are positioned opposite each other in the radial direction. Alternatively, one roller section may have multiple rollers. The straightening roller may not have roller sections or auxiliary roller sections.

[0120] In Embodiment 1, the deformation reduction device 30 includes, in order from upstream to downstream in the conveying direction TR, a second heating furnace 31, a straightening roller 32, and a third take-up machine 33. In Modification 3 of Embodiment 1, the deformation reduction device 60 includes, in order from upstream to downstream in the conveying direction TR, a third take-up machine 33, a second heating furnace 31, and a straightening roller 32. However, the second heating furnace, the straightening roller, and the third take-up machine may be arranged in a different order. For example, the deformation reduction device may include, in order from upstream to downstream in the conveying direction, a second heating furnace, a third take-up machine, and a straightening roller. The third take-up machine, as an auxiliary take-up machine, may be located downstream of the heating device in the conveying direction and downstream of the straightening roller in the conveying direction, or downstream of the post-diameter-expanding take-up machine in the conveying direction and upstream of the heating device and the straightening roller in the conveying direction.

[0121] In the modified embodiment 2 described above, the deformation reduction device 50 has a third take-up machine 43 as an auxiliary take-up machine. However, the deformation reduction device may have a straightening roller instead of a third take-up machine in order to reduce the amount of deformation of the expanded resin pipe due to the pressing force of the second take-up machine, which acts as a post-expansion take-up machine. The straightening roller presses the expanded resin pipe in the radial direction at a position in the circumferential direction of the expanded resin pipe that is different from the position pressed by the post-expansion take-up machine, and guides it downstream in the conveying direction.

[0122] In the second embodiment described above, the wall thickness measuring device 51 is located at TR1 downstream in the transport direction of the second take-up machine 27. However, the wall thickness measuring device may be located upstream in the transport direction of the second take-up machine and downstream in the transport direction of the second cooling water tank. This allows for a shorter interval between the heating timing and the wall thickness measurement timing. As a result, the accuracy of predicting the heating temperature can be improved.

[0123] In the above embodiment 2, the circumferential positions of the 12 thickness measuring sensors TK1 to TK12 correspond to the circumferential positions of the 12 heaters HT1 to HT12. However, the thickness measuring device may have two or more thickness measuring sensors. The heating device may have two or more heaters. The number of thickness measuring sensors in the thickness measuring device and the number of heaters in the temperature control device may be different. In this case, some of the multiple thickness measuring sensors may be linked to one heater, or some of the multiple heaters may be linked to one thickness measuring sensor. The heating device may have a fan for temperature control. The temperature control device may control the fan in addition to the heaters. [Industrial applicability]

[0124] The present invention can be used for a manufacturing apparatus for resin pipes produced by extrusion molding, and for a method of manufacturing resin pipes. [Explanation of symbols]

[0125] 1, 11, 12, 2: Manufacturing equipment 21: Extruder 211: Hoppa 212: Cylinder 213: Screw 214: Mold 22: First cooling water tank 23: First pickup machine 24, 241: 1st heating furnace 2410: Temperature controller 25: Diameter expansion device 251 :Support 252: Mandrel 26: Second cooling water tank 261: Nozzle 27: Second pickup machine 270: Recess 271, 272, 273, 274: Chuck 30, 40, 50, 60: Deformation reduction device 31:Second heating furnace 32: Orthopedic roller 320: Support plate 3201: Roller holding part 3202: Laura 321, 322, 323, 324: Roller section 325: Support plate 326: Auxiliary roller section 33, 43: Third collection machine 430: Recess 431, 432, 433, 434: Chuck 51: Wall thickness measuring device 52: Temperature control device HT1: Heater PT1: Tubular material PT10: Resin pipe PT2: Expanded diameter resin pipe TK1: Thickness measurement sensor

Claims

1. A manufacturing apparatus for resin pipes that produces resin pipes by extrusion molding, A diameter-expanding device for forming an expanded resin tube by expanding the diameter of the tubular material of the resin tube, which has been heated at a temperature below the melting point of the resin material constituting the resin tube, using a mandrel; A post-expanded take-up machine located downstream in the conveying direction of the diameter-expanding device in the manufacturing apparatus, which presses the expanded diameter resin pipe in its radial direction and sends it downstream in the conveying direction, A deformation reduction device located downstream in the conveying direction of the post-expansion take-up machine reduces the amount of deformation of the expanded resin pipe in the radial direction due to the pressing of the post-expansion take-up machine, Equipped with, Manufacturing equipment for resin pipes.

2. In the resin pipe manufacturing apparatus according to claim 1, The deformation reduction device has a straightening roller that guides the expanded resin pipe downstream in the conveying direction while pressing the expanded resin pipe in the radial direction at a position different in the circumferential direction from the position pressed by the expanded post-take machine, Manufacturing equipment for resin pipes.

3. In the resin pipe manufacturing apparatus according to claim 2, The deformation reduction device is A heating device located downstream in the conveying direction of the diameter-expanded take-up machine and upstream in the conveying direction of the straightening roller, which heats the diameter-expanded resin pipe to a temperature at which the diameter-expanded resin pipe can be deformed, An auxiliary take-up machine is located downstream of the heating device and the straightening roller in the conveying direction, or downstream of the diameter-expanded take-up machine in the conveying direction, and upstream of the heating device and the straightening roller in the conveying direction, and presses the diameter-expanded resin pipe in its radial direction while sending it downstream in the conveying direction. It further possesses, Manufacturing equipment for resin pipes.

4. In the resin pipe manufacturing apparatus according to claim 1, The deformation reduction device is A heating device located downstream in the conveying direction of the post-expansion take-up machine, which heats the expanded resin pipe to a temperature at which the expanded resin pipe can be deformed, An auxiliary take-up machine located downstream of the heating device in the conveying direction, which presses the enlarged resin pipe in its radial direction and sends it downstream in the conveying direction, Having, Manufacturing equipment for resin pipes.

5. In the resin pipe manufacturing apparatus according to claim 1, The deformation reduction device is located downstream of the transport direction of the post-expansion take-up machine and has an auxiliary take-up machine that presses the expanded resin pipe in its radial direction while sending it downstream in the transport direction. Manufacturing equipment for resin pipes.

6. In the resin pipe manufacturing apparatus according to any one of claims 3 to 5, The auxiliary pull-up machine presses the expanded resin pipe in the radial direction at a position different from the position pressed by the expanded-diameter pull-up machine in the circumferential direction of the expanded resin pipe, and then feeds it downstream in the conveying direction. Manufacturing equipment for resin pipes.

7. In the resin pipe manufacturing apparatus according to claim 1, A heating furnace located upstream in the conveying direction of the diameter expansion device, which heats the tubular material of the resin pipe to a temperature below the melting point of the resin material constituting the resin pipe, A wall thickness measuring device located downstream in the conveying direction of the diameter-expanded take-up machine, which measures the wall thickness at at least a portion of the circumferential position of the diameter-expanded resin pipe, A temperature control device controls the temperature of the heating furnace according to the position where the wall thickness measuring device measures the wall thickness and the measured wall thickness of the enlarged diameter resin pipe, Having, Manufacturing equipment for resin pipes.

8. In the resin pipe manufacturing apparatus according to claim 7, The wall thickness measuring device measures the wall thickness at multiple positions in the circumferential direction with respect to the axis of the enlarged diameter resin tube. The aforementioned heating furnace is The passage through which the resin pipe passes, A plurality of heaters are positioned in a circumferential direction with respect to the axis of the resin pipe passing through the passage, It has, The temperature control device controls the temperature of the plurality of heaters according to the thickness of the plurality of positions measured by the thickness measuring device. Manufacturing equipment for resin pipes.

9. In a resin pipe manufacturing apparatus according to any one of claims 1 to 5, claim 7, or claim 8, The aforementioned resin material is polyethylene. Manufacturing equipment for resin pipes.

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