A Y-type layout structure of an oriented rigid polyvinyl chloride pipe production line

Abstract

The invention discloses a Y-shaped layout structure of an oriented rigid polyvinyl chloride pipe production line, which belongs to the field of plastic processing and molding, including an extrusion die body diverter with a Y-shaped appearance, an external fixed thrust device arranged at the front end of the extrusion die body diverter, an orientation expansion device arranged at the rear end of the extrusion die body diverter, a first extruder and a second extruder arranged at both sides of the extrusion die body diverter, respectively, and an internal cooling circulation system arranged inside the extrusion die body diverter and inside the PVC blank tube before orientation and inside the PVC-O tube after orientation; the expansion die of the orientation expansion device is mechanically connected to the external fixed thrust device through a pull rod; the pull rod passes through the inside of the extrusion die body diverter and does not contact any part of the extrusion die body diverter. The present invention can realize the rapid adjustment of the temperature of the pipe material, so that the extruder and the extrusion die are no longer at risk of being damaged by traction and stretching, improve production efficiency and production capacity, and reduce energy consumption.

Description

Technical Field

[0001] The invention relates to the technical field of plastic processing and molding, in particular to a Y-shaped layout structure of an oriented rigid polyvinyl chloride pipe production line. Background Art

[0002] Biaxially oriented rigid polyvinyl chloride (hereinafter referred to as PVC-O) is the latest evolution of PVC pipes. The pipes are manufactured through a special orientation processing technology. The PVC-U pipes produced by the extrusion method are stretched axially and radially, so that the PVC long-chain molecules in the pipes are arranged regularly in the biaxial direction, and a new type of PVC pipe with high strength, high toughness, high impact resistance and fatigue resistance is obtained. Due to its structural characteristics, the strength, toughness, low temperature impact resistance, fatigue resistance, and stress cracking resistance of PVC-O pipe materials are greatly improved compared with PVC-U pipes. The inner wall surface of the pipe is smoother, and the head loss of the pipe for pressure water delivery is low. It can be widely used in municipal water supply and drainage, drinking water systems, pressure sewage systems, and efficient farmland irrigation systems.

[0003] PVC-O pipes can be oriented in the circumferential and axial directions through different processing techniques. The oriented pipes have improved circumferential strength, impact resistance and fatigue resistance. The layered structure of the pipe wall eliminates the risk of long-distance rapid crack propagation. Existing PVC-O pipe production lines such as Figure 1 As shown, it includes gravity feeding system A, extruder B, die head C, vacuum sizing box D, primary cooling box E, primary traction machine F, heating furnace G, expansion device H, secondary cooling box I, secondary traction machine J, cutting machine K and control system. The direction of the extruder is set to the front end, and the direction of the cutting machine is set to the rear end. The expansion device is connected to the die head by a rigid tie rod. Due to the deadweight of the expansion device, the threaded connection strength is required to be high, which can only be solved by improving the bending resistance of the tie rod and the shear resistance of the joint. A circulation loop cannot be formed inside the pipe, and the temperature regulation of the pipe can only rely on external cooling water for heat exchange, which is inefficient. When the pipe is oriented and expanded, it is pulled backward by the secondary traction machine, and the maximum pulling force reaches hundreds of thousands of Newtons. The die is the end point of the force. The large pulling force is very likely to damage the die structure and even the extruder barrel mechanically connected to the die. The internal space of the die is the flow channel for material flow. All the channels of the built-in pipelines and other accessories can only be opened from the diversion shuttle, which further reduces the structural strength of the die. Summary of the invention

[0004] The technical problem to be solved by the present invention is to provide a Y-shaped layout structure of an oriented rigid polyvinyl chloride pipe production line, so that the stretching device has an external stress point, increases air circulation in the pipe, improves cooling efficiency, increases production capacity, and reduces energy consumption.

[0005] In order to solve the above technical problems, the technical solution adopted by the present invention is:

[0006] A Y-shaped layout structure of an oriented rigid polyvinyl chloride pipe production line comprises an extrusion die body flow diversion device with a Y-shaped appearance, an external fixed thrust device arranged at the front end of the extrusion die body flow diversion device, an orientation expansion device arranged at the rear end of the extrusion die body flow diversion device, a first extruder and a second extruder respectively arranged at both sides of the extrusion die body flow diversion device, and an internal cooling circulation system arranged inside the extrusion die body flow diversion device, inside a PVC blank pipe before orientation, and inside a PVC-O pipe after orientation; the expansion die of the orientation expansion device is mechanically connected to the external fixed thrust device through a tie rod; the tie rod passes through the inside of the extrusion die body flow diversion device and does not contact any part of the extrusion die body flow diversion device.

[0007] A further improvement of the technical solution of the present invention is that: the extrusion die body diversion device includes an outer die and an inner die; a first material flow channel and a second material flow channel are arranged between the outer die and the inner die; the first material flow channel is connected to the first extruder, and the second material flow channel is connected to the second extruder; a hollow straight-through structure coaxial with the production line is arranged inside the inner die; the first material flow channel and the second material flow channel form an angle of 45° with the hollow straight-through structure.

[0008] A further improvement of the technical solution of the present invention is that the other end of the first material flow channel and the second material flow channel coaxial with the outlet is a circular channel without any obstruction.

[0009] A further improvement of the technical solution of the present invention is that the first material flow channel and the second material flow channel are each a semicircular flow channel with a circumference of 180°, and the two merge into a closed circle.

[0010] A further improvement of the technical solution of the present invention is that the external fixed thrust device is a trapezoidal frame structure that is narrow at the top and wide at the bottom, and is fixedly installed on the horizontal ground at the front end of the extrusion die diversion device. The force point is within the range of 1.0 to 1.3 m from the ground, and the trapezoidal frame can withstand a maximum axial tensile force of 35 tons parallel to the ground.

[0011] A further improvement of the technical solution of the present invention is that: one end of the pull rod is fixed on the trapezoidal frame and mechanically connected in a cross-fixing manner, and the center height can be adjusted; the other end of the pull rod is mechanically connected to the expansion mold; the pull rod is a hollow structure, and a number of temperature sensors for measuring the inner wall temperature of the pipe are arranged inside.

[0012] A further improvement of the technical solution of the present invention is that: the internal cooling circulation system comprises a fluid pipeline, a cooling fluid and a circulation device; the fluid pipeline passes through the hollow straight-through structure of the inner mold, and an air flow channel for cooling air is formed inside the PVC blank tube before orientation and inside the PVC-O tube after orientation; the inlet end of the fluid pipeline is arranged in the tube cutting area, and the outlet end is arranged on the external fixed thrust device (1).

[0013] A further improvement of the technical solution of the present invention lies in that: a double semicircular ring-shaped baffle plate capable of adjusting the size of the air flow channel area is provided at the outlet end of the fluid pipeline; the double semicircular ring-shaped baffle plate includes a first baffle plate and a second baffle plate; air holes are provided on the first baffle plate and the second baffle plate; when the first baffle plate and the second baffle plate are completely closed, the air holes on the two layers do not overlap.

[0014] A further improvement of the technical solution of the present invention is that an elastic temperature measuring device is also arranged inside the extrusion die diversion device, inside the PVC blank tube before orientation, and inside the PVC-O tube after orientation. A plurality of radial temperature measuring elements are arranged at the end of the elastic temperature measuring device, which can be adjusted in the circumferential direction as the tube diameter shrinks and closely adhere to the inner wall of the tube.

[0015] A further improvement of the technical solution of the present invention is that the structure also includes a vacuum sizing box, a primary cooling box, a primary traction machine and a heating furnace which are sequentially arranged between the extrusion die body diversion device and the orientation expansion device; and a secondary cooling box, a secondary traction machine and a cutting machine are also sequentially arranged at the rear end of the orientation expansion device.

[0016] Due to the adoption of the above technical solution, the technical progress achieved by the present invention is:

[0017] 1. The extrusion die body diversion device in the present invention is to design the feed end of the die head on the original production line into a "Y-shape", changing one feed port into two feed ports, and the angle between the two feed ports is 45°. This structure makes it possible for no material to enter the feed end corresponding to the material outlet, and the inside of the inner die can directly pass through to the die head feed end to form a hollow straight-through channel.

[0018] 2. The orientation expansion device in the present invention connects the expansion die to the external fixed thrust device arranged at the front end of the head through a pull rod. The pulling force of the traction machine on the orientation expansion device is transmitted to the external fixed thrust device, so that the extrusion die body diverter device (original head) and the extruder are no longer subjected to tensile force, reducing the risk of the extrusion die body diverter device (original head) and the extruder being damaged by pulling.

[0019] 3. The internal cooling circulation system arranged inside the extrusion die body diversion device, inside the PVC blank tube before orientation, and inside the PVC-O tube after orientation in the present invention is a straight cooling air duct, which can use the air temperature difference at different positions to form heat convection, and a continuous cold air flow takes away the heat in the tube, thereby automatically adjusting the temperature in the tube; the arrangement of the internal cooling circulation system not only realizes the rapid adjustment of the temperature of the PVC-O pipe material, but also can shorten the length of the primary cooling box and the secondary cooling box (the length can be shortened by 1 / 3 to 1 / 2), thereby shortening the length of the entire production line, improving production efficiency and capacity, reducing the one-time investment in plant and equipment, and reducing energy consumption.

[0020] 4. The present invention arranges a double-layer double semicircular ring baffle plate at the gas outlet end of the fluid pipeline, which can adjust the area of ​​the air flow channel; air holes are arranged on the double semicircular ring baffle plate, and after the two layers of plates are completely closed, the openings of the two layers of baffle plates basically do not overlap, and the airflow is maximum when the first baffle plate and the second baffle plate are both in the open state. By adjusting the position and closing state of the first baffle plate and the second baffle plate, the opening rate, that is, the area of ​​the air channel is adjusted.

[0021] 5. The present invention arranges a compressible elastic temperature measuring device capable of measuring the temperature of the inner wall of the pipe at any time inside the diversion device of the extrusion die, inside the PVC blank pipe before orientation, and inside the PVC-O pipe after orientation. The support rod of each temperature measuring element of the elastic temperature measuring device can move axially along the inner wall of the pipe. A plurality of radial temperature measuring elements are arranged at the end of the elastic temperature measuring device. The temperature measuring elements can be adjusted in the circumferential direction as the pipe diameter shrinks and are closely attached to the inner wall of the pipe. The temperature measuring elements monitor the temperature of the inner wall of the pipe in real time. Since the maximum wall thickness of the pipe reaches 60 mm, the temperature difference between the inside and outside of the pipe wall is monitored and calculated, and the gas flow rate of the internal cooling circulation system is adjusted to obtain the temperature value required by the process.

[0022] 6. Since the plastic pipe is about 180-200°C after being extruded from the die, it needs to be cooled to the required temperature within a certain length (i.e. within a certain time). After the expansion is completed, the wall thickness of the pipe becomes thinner. The cooling efficiency of conventional external surface water spraying is sufficient, and internal cooling is not required. Therefore, the present invention arranges a plurality of temperature sensors in the hollow pull rod to timely measure the temperature of the inner wall of the pipe, understand the temperature value of the PVC blank pipe at a specific position before orientation, so as to facilitate the adjustment of the internal cooling circulation system. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art are briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative labor.

[0024] Figure 1 It is a schematic diagram of the layout of an existing oriented rigid polyvinyl chloride pipe production line in the background technology of the present invention;

[0025] Figure 2 It is a schematic diagram of a Y-shaped layout structure of an oriented rigid polyvinyl chloride pipe production line provided in an embodiment of the present invention;

[0026] Figure 3 is a schematic diagram of the structure of the first baffle provided in an embodiment of the present invention Figure 1 ;

[0027] Figure 4 is a schematic diagram of the structure of the second baffle provided in an embodiment of the present invention Figure 2 ;

[0028] Figure 5 Schematic diagram of an elastic temperature measuring device provided in an embodiment of the present invention Figure 1 ;

[0029] Figure 6 Schematic diagram of an elastic temperature measuring device provided in an embodiment of the present invention Figure 2 ;

[0030] Among them, 1. external fixed thrust device; 1-1. tension sensor; 1-2. expansion bolt; 2. extrusion die body diversion device; 2-1. outer die; 2-2. inner die; 2-3. first material flow channel; 2-4. second material flow channel; 3. orientation expansion device; 3-1. expansion die; 4. PVC blank tube; 5. PVC-O tube; 6. pull rod; 7. fluid pipeline; 7-1. first baffle; 7-2. second baffle; 7-3. air hole; 8. temperature sensor; 9. cooling fluid; 10. temperature measuring element; A. gravity feeding system; B. extruder; C. die head; D. vacuum sizing box; E. primary cooling box; F. primary traction machine; G. heating furnace; H. expansion device; I. secondary cooling box; J. secondary traction machine; K. cutting machine. DETAILED DESCRIPTION

[0031] It should be noted that the terms "including" and "having" and any variations in the specification and claims of the present invention and the above-mentioned drawings are intended to cover non-exclusive inclusions. For example, a process, method, system, product or device that includes a series of steps or units is not necessarily limited to those steps or units clearly listed, but may include other steps or units that are not clearly listed or inherent to these processes, methods, products or devices.

[0032] In the description of the present invention, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside" and the like indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the referred device or element must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as limiting the present invention.

[0033] In addition, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" and "second" may explicitly or implicitly include at least one of the features. In the description of the present invention, the meaning of "several" is at least two, such as two, three, etc., unless otherwise clearly and specifically defined.

[0034] The present invention is further described in detail below with reference to the accompanying drawings and embodiments:

[0035] like Figure 2 As shown, a Y-shaped layout structure of an oriented rigid polyvinyl chloride pipe production line includes an extrusion die diverter 2 with a Y-shaped appearance, an external fixed thrust device 1 arranged at the front end of the extrusion die diverter 2, an orientation expansion device 3 arranged at the rear end of the extrusion die diverter 2, a first extruder and a second extruder respectively arranged on both sides of the extrusion die diverter 2, and an internal cooling circulation system arranged inside the extrusion die diverter 2 and inside the PVC blank pipe 4 before orientation and inside the PVC-O pipe 5 after orientation; the expansion die 3-1 of the orientation expansion device 3 is mechanically connected to the external fixed thrust device 1 through a pull rod 6; the pull rod 6 passes through the extrusion die diverter 2 and does not contact any part of the extrusion die diverter 2.

[0036] Furthermore, the extrusion die body diversion device 2 includes an outer die 2-1 and an inner die 2-2; a first material flow channel 2-3 and a second material flow channel 2-4 are arranged between the outer die 2-1 and the inner die 2-2; the first material flow channel 2-3 is connected to the first extruder, and the second material flow channel 2-4 is connected to the second extruder, so the two extruders are not on the axis of the production line; a hollow straight-through structure coaxial with the production line is arranged inside the inner die 2-2; the first material flow channel 2-3 and the second material flow channel 2-4 are at an angle of 45° to the hollow straight-through structure. The inner die 2-2 gets rid of the structure in which the traditional die head is connected and supported by the diversion shuttle, and the inner die 2-2 and the outer die 2-1 have no contact, and the first material flow channel 2-3 and the second material flow channel formed between the two are not blocked.

[0037] Furthermore, the other end of the first material flow channel 2-3 and the second material flow channel 2-4 coaxial with the outlet is a circular channel without any obstruction. The outer mold 2-1 and the inner mold 2-2 can be fixed by a support device set on the ground, so there is no need to set a traditional diversion bracket in the first material flow channel 2-3 and the second material flow channel 2-4. The inner mold 2-2 gets rid of the structure of the traditional machine head connected and supported by the diversion shuttle. There is no contact between the inner mold 2-2 and the outer mold 2-1, so the channel formed between the two (the first material flow channel 2-3 and the second material flow channel 2-4) is unobstructed.

[0038] Furthermore, the first material flow channel 2-3 and the second material flow channel 2-4 are semicircular flow channels with a circumference of 180° respectively, and the two merge into a closed circle.

[0039] Furthermore, the external fixed thrust device 1 is a trapezoidal frame structure that is narrow at the top and wide at the bottom. It is fixed on the horizontal ground at the front end of the extrusion die diversion device 2 by a number of expansion bolts 1-2. The force point is within the range of 1.0 to 1.3 m from the ground. The maximum axial tension parallel to the ground that the trapezoidal frame can withstand is 35 tons.

[0040] Furthermore, one end of the tie rod 6 is fixed on the trapezoidal frame, and is mechanically connected in a cross-fixed manner, and the center height can be adjusted; the other end of the tie rod 6 is mechanically connected to the expansion die 3-1; the tie rod 6 is a hollow structure (a stainless steel tube, and the diameter of the tie rod 6 is very small relative to the diameter of the fluid pipeline 7), and a plurality of temperature sensors 8 for measuring the inner wall temperature of the pipe are arranged inside. The distance between the expansion die 3-1 and the end face of the extrusion die body diverter 2 can be adjusted by the expansion bolt 1-2 arranged at the bottom end of the trapezoidal frame.

[0041] Furthermore, the internal cooling circulation system includes a fluid pipeline 7, a cooling fluid 9 and a circulation device; the fluid pipeline 7 passes through the hollow straight-through structure of the inner mold 2-2, and forms an airflow channel for cooling air inside the PVC blank tube 4 before orientation and inside the PVC-O tube 5 after orientation; the inlet end of the fluid pipeline 7 is set in the pipe cutting area, and the outlet end is set on the trapezoidal frame. In the entire airflow channel, the cooling air under room temperature environment continuously flows from the cutting machine K area on the production line to the extrusion die body diverter device 2 area, and flows out from the front end of the extrusion die body diverter device 2 to form a cooling loop.

[0042] Further, such as Figure 3-4As shown, the outlet end of the fluid conduit 7 is provided with a double semicircular ring baffle that can adjust the size of the airflow channel area; the double semicircular ring baffle includes a first layer baffle 7-1 and a second layer baffle 7-2; the first layer baffle 7-1 and the second layer baffle 7-2 are both provided with air holes 7-3; when the first layer baffle 7-1 and the second layer baffle 7-2 are completely closed, the air holes 7-3 on the two layers do not overlap. When the first baffle and the second baffle are both in the open state, the airflow is maximum, and the opening rate, that is, the size of the air channel area, is adjusted by adjusting the position and closing state of the first baffle and the second baffle.

[0043] Further, such as Figure 5-6 As shown, an elastic temperature measuring device is also provided inside the extrusion die flow dividing device 2, inside the PVC blank tube 4 before orientation, and inside the PVC-O tube 5 after orientation. A plurality of radial temperature measuring elements 10 are provided at the end of the elastic temperature measuring device, which can be adjusted along with the tube diameter contraction in the circumferential direction and closely attached to the inner wall of the tube. The temperature measuring element 10 monitors the temperature of the inner wall of the tube in real time. Since the maximum thickness of the tube wall is 60 mm, the temperature difference between the inner and outer walls of the tube wall is monitored and calculated, and the gas flow rate of the internal cooling circulation system is adjusted to obtain the temperature value required by the process.

[0044] The inside of the hollow straight-through structure of the inner mold 2-2 is a high temperature zone with a temperature of 190-210°C; the temperature of the part inside the PVC-O tube 5 that contacts the expansion mold 3-1 is the same as that of the expansion mold 3-1, and the temperature gradually decreases in the cutting area.

[0045] Furthermore, the structure also includes a vacuum sizing box D, a primary cooling box E, a primary traction machine F and a heating furnace G which are sequentially arranged between the extrusion die body diversion device 2 and the orientation expansion device 3; a secondary cooling box I, a secondary traction machine J and a cutting machine K are also sequentially arranged at the rear end of the orientation expansion device 3. Figure 2 Not shown, please refer to Figure 1 The production control system uses the control system of the original production line and adds some related parameter controls.

[0046] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A Y-shaped layout structure of an oriented rigid polyvinyl chloride pipe production line, characterized in that: The invention comprises an extrusion die diverter (2) having a Y-shaped appearance, an external fixed thrust device (1) arranged at the front end of the extrusion die diverter (2), an orientation expansion device (3) arranged at the rear end of the extrusion die diverter (2), a first extruder and a second extruder respectively arranged at both sides of the extrusion die diverter (2), and an internal cooling circulation system arranged inside the extrusion die diverter (2) and inside a formed PVC blank tube (4) and a PVC-O tube (5); the expansion die (3-1) of the orientation expansion device (3) is mechanically connected to the external fixed thrust device (1) via a tie rod (6); the tie rod (6) passes through the interior of the extrusion die diverter (2) and does not contact any part of the extrusion die diverter (2).

2. The Y-shaped layout structure of an oriented rigid polyvinyl chloride pipe production line according to claim 1 is characterized in that: The extrusion die body flow dividing device (2) comprises an outer die (2-1) and an inner die (2-2); a first material flow channel (2-3) and a second material flow channel (2-4) are arranged between the outer die (2-1) and the inner die (2-2); the first material flow channel (2-3) is connected to the first extruder, and the second material flow channel (2-4) is connected to the second extruder; a hollow straight-through structure coaxial with the production line is arranged inside the inner die (2-2); the first material flow channel (2-3) and the second material flow channel (2-4) form an angle of 45° with the hollow straight-through structure.

3. The Y-shaped layout structure of an oriented rigid polyvinyl chloride pipe production line according to claim 2 is characterized in that: The other end of the first material flow channel (2-3) and the second material flow channel (2-4) that is coaxial with the outlet is a circular channel without any obstruction.

4. The Y-shaped layout structure of an oriented rigid polyvinyl chloride pipe production line according to claim 2 is characterized in that: The first material flow channel (2-3) and the second material flow channel (2-4) are each semicircular flow channels with a circumference of 180°, and the two merge to form a closed circle.

5. The Y-shaped layout structure of an oriented rigid polyvinyl chloride pipe production line according to claim 1 is characterized in that: The external fixed thrust device (1) is a trapezoidal frame structure that is narrow at the top and wide at the bottom, and is fixedly mounted on the horizontal ground at the front end of the extrusion die body diverter device (2). The force bearing point is within a range of 1.0 to 1.3 m from the ground. The maximum axial tension that the trapezoidal frame can withstand parallel to the ground is 35 t.

6. The Y-shaped layout structure of an oriented rigid polyvinyl chloride pipe production line according to claim 1 is characterized in that: One end of the pull rod (6) is fixed on the trapezoidal frame and mechanically connected in a cross-fixing manner, and the center height can be adjusted; the other end of the pull rod (6) is mechanically connected to the expansion mold (3-1); the pull rod (6) is a hollow structure, and a plurality of temperature sensors (8) for measuring the inner wall temperature of the pipe are arranged inside.

7. The Y-shaped layout structure of an oriented rigid polyvinyl chloride pipe production line according to claim 2 is characterized in that: The internal cooling circulation system comprises a fluid pipeline (7), a cooling fluid (9) and a circulation device; the fluid pipeline (7) passes through the hollow straight-through structure of the inner mold (2-2), and forms an air flow channel for cooling air inside the PVC blank tube (4) before orientation and inside the PVC-O tube (5) after orientation; the inlet end of the fluid pipeline (7) is arranged in the tube cutting area, and the outlet end is arranged on the external fixed thrust device (1).

8. The Y-shaped layout structure of the oriented rigid polyvinyl chloride pipe production line according to claim 7 is characterized by: A double semicircular ring-shaped baffle plate capable of adjusting the size of the air flow channel area is arranged at the outlet end of the fluid pipeline (7); the double semicircular ring-shaped baffle plate comprises a first layer of baffle plates (7-1) and a second layer of baffle plates (7-2); air holes (7-3) are provided on the first layer of baffle plates (7-1) and the second layer of baffle plates (7-2); when the first layer of baffle plates (7-1) and the second layer of baffle plates (7-2) are completely closed, the air holes (7-3) on the two layers do not overlap.

9. The Y-shaped layout structure of an oriented rigid polyvinyl chloride pipe production line according to claim 1 is characterized in that: An elastic temperature measuring device is also provided inside the extrusion die body flow dividing device (2), inside the PVC blank tube (4) before orientation, and inside the PVC-O tube (5) after orientation. A plurality of radial temperature measuring elements (10) are provided at the end of the elastic temperature measuring device. The temperature measuring elements (10) can be adjusted in the circumferential direction as the diameter of the tube shrinks, and are closely attached to the inner wall of the tube.

10. The Y-shaped layout structure of an oriented rigid polyvinyl chloride pipe production line according to claim 1, characterized in that: The structure further comprises a vacuum sizing box (D), a primary cooling box (E), a primary traction machine (F) and a heating furnace (G) which are sequentially arranged between the extrusion die body diversion device (2) and the orientation expansion device (3); and a secondary cooling box (I), a secondary traction machine (J) and a cutting machine (K) are sequentially arranged at the rear end of the orientation expansion device (3).

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