A double-wall corrugated plastic pipe forming equipment and connection method

Abstract

The present invention belongs to the technical field of double-wall corrugated pipes, and in particular, relates to a double-wall corrugated plastic pipe forming device and a connection method, comprising a double-layer extrusion assembly, a first shaping assembly, and a second shaping assembly. The double-layer extrusion assembly is used to continuously and synchronously extrude the inner tube and the outer tube of the double-wall corrugated pipe and blow room temperature air between the inner tube and the outer tube. The first shaping assembly is used to shape the corrugated outer tube. The second shaping assembly is used to support the moving inner tube and the outer tube from the inner tube and shape the inner tube. In the present invention, the die assemblies in the two first shaping assemblies on both sides of the shaping cylinder are concentrated on the pressure-applying side of the double-wall corrugated pipe. After completing the pressure-applying to the double-wall corrugated pipe, the die assembly automatically slides on the guide seat to the initial end position of the pressure-applying and supplements the die assembly on the pressure-applying side of the double-wall corrugated pipe under the drive of the support assembly, effectively reducing the number of die assemblies and effectively reducing equipment costs.

Description

Technical Field

[0001] The invention belongs to the technical field of double-wall corrugated pipes, and in particular relates to a double-wall corrugated plastic pipe forming device and a connecting method. Background Art

[0002] Double-wall corrugated pipe is a new type of high-strength, lightweight, corrosion-resistant non-metallic pipe material with excellent chemical stability, aging resistance and environmental stress cracking resistance. It is made of high-density polyethylene (HDPE) or polyvinyl chloride (PVC-U) and other polymer materials, with an inner and outer layer structure, a smooth inner wall and an annular corrugated outer wall. The characteristics of double-wall corrugated pipe include high ring stiffness, light weight, corrosion resistance, good sealing performance, easy installation, low maintenance cost and environmental protection. It is widely used in water supply, drainage, sewage, exhaust and other fields.

[0003] Double-arm corrugated pipe production equipment usually includes extruder, corrugation forming machine, cooling system, cutting machine and feeding device, etc. These equipment can be configured according to the corrugated pipe material (such as PE, PVC, etc.) and the required pipe diameter. The degree of automation and technical parameters of the production equipment will affect the production efficiency and product quality.

[0004] The current production of double-wall corrugated pipes is to first use two molding machines to separately mold the outer corrugated pipe and the inner smooth pipe, and then assemble and glue the two pipes. There are many processes, and the strength of the glue is not as good as the strength of molding together and contact bonding before cooling.

[0005] The patent with application number 201910028912.2 can extrude the inner and outer layers of the corrugated pipe at the same time through a double-layer extrusion device. After the inner and outer layers are extruded at the same time, the inner layer is adsorbed and formed by the sizing cylinder. The outer layer's die presses the outer layer after the inner layer is shaped. Before the outer layer is pressurized, the outer layer that is extruded and in a soft state will be partially bonded to the inner layer. After the outer layer is molded, there will be a situation where there is no space between the inner and outer layers due to continuous adhesion. The reduction in space between the inner and outer layers of the double-wall corrugated pipe means that the corrugated pipe uses more material, has a high cost and a large weight at the same strength. At the same time, the inner layer will slide relative to the sizing cylinder when it is shaped because the inner sizing cylinder is stationary. The inner wall of the inner layer will be rough due to the action of the sizing cylinder, affecting the production quality of the corrugated pipe.

[0006] There are a large number of molds for pressure forming the outer layer, and the single-side molds are all arranged in a full circle of reciprocating cycles. Due to the high processing cost of the molds, the cost of the entire equipment is high.

[0007] In addition, the cooling rate, which is an important indicator in bellows production, still has room for improvement.

[0008] The present invention designs a double-wall corrugated plastic pipe forming device and a connecting method to solve the above problems. Summary of the invention

[0009] Based on this, it is necessary to provide a double-wall corrugated plastic pipe forming device and a connection method for the problems existing in the current double-wall corrugated pipe forming equipment. The present invention extrude the inner layer pipe and the outer layer pipe of the double-wall corrugated pipe at the same time through the extrusion barrel and perform synchronous contact bonding on the two layers, so the strength of the double-wall corrugated pipe product of the present invention is higher than that of the double-wall corrugated pipe in which the two layers are respectively formed and then glued, and the double-wall corrugated pipe product of the present invention has fewer forming processes and higher production efficiency. The present invention blows room temperature air between the inner layer pipe and the outer layer pipe extruded at the same time through the air delivery channel between the first extrusion groove and the second extrusion groove on the extrusion barrel, so that the outer layer pipe and the inner layer pipe will not be locally adhered before being pressed by the first shaping component, and it is ensured that there will be no local continuous solid situation between the outer layer pipe and the inner layer pipe after the outer layer pipe and the inner layer pipe are pressed and shaped by the first shaping component, so that the part between the outer layer pipe and the inner layer pipe that needs to be hollowed remains in a hollow state, and the material consumption and the weight of the final product are reduced while maintaining the same strength, thereby reducing the material cost of the double-wall corrugated pipe. The surface film of the sizing cylinder for shaping and supporting the inner tube in the present invention moves synchronously with the inner tube under the drive of the support assembly, ensuring that the inner wall of the inner tube is smooth. The negative pressure generated by the second spiral groove and the third spiral groove connected on the inner and outer walls of the shaping cylinder in the second shaping assembly and the second negative pressure hole on the film can promote the rapid shaping of the inner tube. At the same time, the air supply channel between the first extrusion groove and the second extrusion groove on the extrusion cylinder blows room temperature air between the inner tube and the outer tube, which effectively cools the outer wall of the inner tube and the inner wall of the outer tube. The die assemblies in the two first shaping assemblies on both sides of the shaping cylinder in the present invention are concentrated on the pressure side of the double-walled corrugated pipe. After completing the pressure on the double-walled corrugated pipe, the die assembly automatically slides on the guide seat to the initial end position of the pressure and supplements the die assembly on the pressure side of the double-walled corrugated pipe under the drive of the support assembly, effectively reducing the number of die assemblies and effectively reducing equipment costs.

[0010] The above purpose is achieved through the following technical solutions:

[0011] A double-wall corrugated plastic pipe forming device, used for forming double-wall corrugated pipes, comprising:

[0012] The double-layer extrusion assembly is used for continuously and synchronously extruding the inner layer tube and the outer layer tube of the double-wall corrugated pipe and blowing normal temperature air between the inner layer tube and the outer layer tube.

[0013] The first shaping component is used for shaping the corrugated outer tube; the first shaping component includes two guide seats symmetrically distributed on both sides of the outer tube, and the side walls of the guide seats are driven by a number of die assemblies that translate along the annular guide groove and are only gathered at the outer tube to press the outer tube to shape the outer tube. The die assembly includes a semicircular forming mold, and the inner wall of the forming mold is provided with a first spiral groove. The wall surface of the first spiral is densely covered with first negative pressure holes distributed along the spiral and connected to the first negative pressure tube at the upper end of the outer side of the forming mold. The first spiral grooves of adjacent forming molds on the same guide seat are connected, and the first spiral grooves of the butt-jointed forming molds on the two guide seats form a complete spiral.

[0014] The second shaping component is used for supporting the moving inner tube and outer tube from inside the inner tube and shaping the inner tube; the second shaping component comprises a shaping cylinder which is located in the inner tube and has a smooth surface, the inner and outer walls of the shaping cylinder are respectively provided with a second spiral groove and a third spiral groove which are connected by densely distributed connecting holes, the surface of the shaping cylinder is covered with a film which is densely distributed with second negative pressure holes, a supporting component is arranged in the middle of the shaping cylinder for supporting and positioning the shaping cylinder and driving the film and the inner tube to move synchronously, the supporting component forms a negative pressure space in the shaping cylinder which causes the second spiral groove and the third spiral groove to generate negative pressure.

[0015] In one embodiment, the double-layer extrusion assembly includes an extrusion barrel installed on a bracket, and a first extrusion groove and a second extrusion groove communicating with one end of the extrusion barrel are provided in the barrel wall of the extrusion barrel, a first heating layer is provided in the large-diameter wall of the first extrusion groove, and a second heating layer is provided in the small-diameter wall of the second extrusion groove, and a plurality of air supply channels uniformly distributed circumferentially and passing through both ends of the extrusion barrel are provided in the barrel wall between the first extrusion groove and the second extrusion groove, and an annular groove communicating with all the air supply channels is provided at the non-extrusion end of the extrusion barrel, and an air inlet on the annular groove is connected to an air pump on the outside of the extrusion barrel through an air supply pipe, and a first feed port and a second feed port 180 degrees apart in the circumferential direction are provided on the wall of the extrusion barrel, the first feed port is connected to the first extrusion groove, and the second feed port is connected to the second extrusion groove, and the first feed port and the second feed port are respectively connected to the extrusion ports of the two extruders.

[0016] In one embodiment, two annular guide grooves distributed up and down are provided on the side wall of the guide seat, and the guide groove consists of a horizontal turning portion, a horizontal straight portion, a lifting turning portion and a return sliding straight portion. The horizontal turning portion is located at the initial end of the molding cylinder, the horizontal straight portion is opposite to the molding cylinder, the lifting turning portion is located at the end of the molding cylinder, and the end of the lifting turning portion is connected to the starting end of the horizontal turning portion through the return sliding straight portion.

[0017] In one embodiment, a spiral air channel corresponding to the first spiral groove is provided in the wall surface of the forming mold, and the spiral air channel is connected with the first spiral groove through a first negative pressure hole. A connecting groove connecting the spiral air channel and the first negative pressure tube is provided in the forming mold, and two guide rods corresponding to the guide grooves are provided on the outer arc wall of the forming mold, and ball heads are provided at the ends of the guide rods, and the ball heads slide in the guide grooves. Two telescopic rods distributed along the axis thereof are provided on the outer arc wall of the forming mold, and the telescopic rods are composed of an outer sleeve fixed to the forming mold and an inner rod sliding in the outer sleeve, and a first spring for driving the inner rod to telescope is provided in the outer sleeve, and a ball seat is provided at the end of the inner rod, and a rolling ball is provided in the ball seat to abut against the side wall of the guide seat, and two second levers distributed up and down are provided on the outer arc wall of the forming mold.

[0018] In one embodiment, the driving assembly includes two first sprockets corresponding to the second levers on the forming mold and two second sprockets corresponding to the first sprockets, the first sprockets are connected to the corresponding second sprockets through a chain, the first sprocket, the first chain and the corresponding chain are located in an accommodating groove on the guide seat, the first sprocket corresponds to the horizontal turning part, the second sprocket corresponds to the horizontal straight part, a plurality of ears are evenly distributed on the chain, a first lever cooperating with the second lever is hinged on the ear through a round pin, the round pin is fixedly connected to the first lever, a vortex spring is connected between the round pin and the ear, a swing limit block for limiting its swing direction is provided on the first lever, the two first sprockets are mounted on a first synchronous shaft, the first synchronous shaft is mounted in the guide seat, and the first synchronous shaft is connected to the output shaft of the first motor on the bracket.

[0019] In one embodiment, the support assembly includes a support cross bar, which is suspended in the middle of the shaping cylinder, and the annular groove end of the support cross bar is fixed on the bracket. The two ends of the support cross bar are respectively installed with a first tripod, and the three legs of the first tripod are each installed with a first roller that abuts against the end of the film and positions the shaping cylinder.

[0020] In one of the embodiments, the supporting crossbar is provided with a plurality of second tripods evenly distributed along its axial direction, and the three legs of the second tripods are all equipped with second rollers for supporting the inner wall of the film.

[0021] In one of the embodiments, two circular plates are installed on the supporting cross bar, and rubber ring plates that cooperate with the film seal are arranged at the edges of the circular plates. The second spiral groove and the third spiral groove on the shaping cylinder are located in the range between the two circular plates. An exhaust hole is opened on the circular plate located on the side of the ring groove. The exhaust hole is connected to the second connecting tube through the first connecting tube, and the second connecting tube is connected to the negative pressure pump on the outer wall of the extrusion cylinder through the second negative pressure tube.

[0022] In one embodiment, three first guide sleeves uniformly distributed in the circumference are provided on the support cross bar, a push rod is radially slidable in the first guide sleeve along the shaping cylinder, a wheel seat is installed at the exposed end of the push rod, a third roller for extruding the film is installed in the wheel seat, a second spring driving the push rod to move outward is provided in the first guide sleeve, a rotating shaft parallel to the push rod is installed on the wheel seat, a shaft sleeve is slidably provided on the rotating shaft, the shaft sleeve is rotatably provided in the rotating seat on the first guide sleeve, a second synchronous shaft is installed on the wheel seat, a sixth gear and a seventh gear are installed on the second synchronous shaft, the sixth gear is meshed with the first gear installed on the rotating shaft, the seventh gear is meshed with the eighth gear installed on the wheel seat, and the eighth gear is meshed with the ninth gear installed on the shaft where the third roller is located, a rotating sleeve is rotatably provided on the support cross bar, a third gear and a fourth gear are installed on the rotating sleeve, the third gear is meshed with the second gear on the shaft sleeve, the fourth gear is meshed with the fifth gear on the output shaft of the second motor, and the second motor is installed on the bracket.

[0023] The connection method of double-wall corrugated pipe is:

[0024] S1. The inner tube and the outer tube are synchronously and continuously extruded from the second extrusion groove and the first extrusion groove of the extrusion barrel. The air supply channel on the extrusion barrel blows room temperature air into the space between the inner tube and the outer tube for cooling to avoid adhesion between the inner tube and the outer tube in a soft state. At the same time, the film moves synchronously with the inner tube under the drive of the three third rollers. The negative pressure generated by the second negative pressure hole on the film adsorbs the inner tube and shapes it.

[0025] S2. With the movement of the inner tube and the outer tube, the die assemblies on the two guide seats apply pressure to the outer tube, and the outer tube and the inner tube are bonded together. At the same time, the die assembly absorbs the outer tube through the first negative pressure hole on its inner wall to form a spiral hollow between the inner tube and the outer tube. The air blown between the inner tube and the outer tube by the air supply duct moves forward through the spiral hollow space, thereby achieving effective cooling of the bonded inner tube and the outer tube.

[0026] A negative pressure cooling assembly is arranged on the top of the guide seat, which provides negative pressure to the first negative pressure pipe in the moving die assembly and transports cooling air into the first spiral groove.

[0027] The beneficial effects of the present invention are:

[0028] 1. The present invention extrude the inner tube and the outer tube of the double-wall corrugated pipe simultaneously through an extruder and perform synchronous contact bonding on the two layers. Therefore, the strength of the double-wall corrugated pipe product of the present invention is higher than that of the double-wall corrugated pipe in which the two layers are formed separately and then glued. In addition, the double-wall corrugated pipe product of the present invention has fewer molding steps and higher production efficiency.

[0029] 2. The present invention blows room temperature air between the inner tube and the outer tube extruded simultaneously through the air supply channel between the first extrusion groove and the second extrusion groove on the extrusion barrel, so that there will be no local adhesion between the outer tube and the inner tube before being pressurized by the first molding component, ensuring that there will be no local continuous solid situation between the outer tube and the inner tube after the outer tube and the inner tube are pressurized and molded by the first molding component, so that the part between the outer tube and the inner tube that needs to be hollow remains in a hollow state, reducing the material consumption and the weight of the final product while maintaining the same strength, thereby reducing the material cost of the double-wall corrugated pipe.

[0030] 3. In the present invention, the surface film of the sizing cylinder for shaping and supporting the inner tube moves synchronously with the inner tube under the drive of the supporting assembly, thereby ensuring that the inner wall of the inner tube is smooth.

[0031] 4. The negative pressure generated by the second spiral groove and the third spiral groove connected on the inner and outer walls of the molding cylinder in the second molding component and the second negative pressure hole on the film in the present invention can promote the rapid molding of the inner tube. At the same time, the air supply channel located between the first extrusion groove and the second extrusion groove on the extrusion cylinder blows room temperature air between the inner tube and the outer tube. The spiral space pressed out by the die assembly on the outer tube will keep the room temperature air flowing in the outer and inner tubes, so that the outer wall of the inner tube and the inner wall of the outer tube are effectively cooled, and the outer tube and the inner tube are bonded together under the pressure of the die assembly.

[0032] 5. In the present invention, the die assemblies in the two first molding assemblies located on both sides of the molding cylinder are concentrated on the pressure side of the double-wall corrugated pipe. After completing the pressure on the double-wall corrugated pipe, the die assembly automatically slides to the initial pressure end position on the guide seat and supplements the die assembly on the pressure side of the double-wall corrugated pipe under the drive of the support assembly, effectively reducing the number of die assemblies and effectively reducing equipment costs. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Figure 1 It is an overall schematic diagram of the present invention.

[0034] Figure 2 Two cross-sectional views of the present invention.

[0035] Figure 3 It is a cross-sectional view of the rear end of the extrusion cylinder and the second shaping component in the present invention.

[0036] Figure 4 It is a cross-sectional view of the middle part of the extrusion cylinder and the second shaping component in the present invention.

[0037] Figure 5 It is a cross-sectional view of the front end of the extrusion cylinder and the second shaping component in the present invention.

[0038] Figure 6It is a side sectional view of the cooperation between the supporting component and the surface film of the shaping cylinder in the second shaping component of the present invention.

[0039] Figure 7 It is a cross-sectional view of the cooperation between the supporting component and the surface film of the shaping cylinder in the second shaping component of the present invention.

[0040] Figure 8 It is a cross-sectional view of the cooperation between the rubber ring plate on the circular plate and the surface film of the shaping cylinder in the second shaping component of the present invention.

[0041] Fig. 9 It is a top sectional view of the driving structure of the die assembly in the first molding assembly of the present invention.

[0042] Fig.10 It is a side sectional view of the cooperation between the support assembly and the guide seat in the present invention.

[0043] Fig.11 It is a cross-sectional view of the cooperation between the support component and the die component in the present invention.

[0044] Fig.12 It is a top sectional view of the cooperation between the die assembly and the guide seat in the present invention.

[0045] Fig.13 It is a partial cross-sectional view of the cooperation between the support component and the die component in the present invention.

[0046] Fig.14 2 are two schematic diagrams of the guide seat in the present invention.

[0047] Fig.15 2 are two schematic diagrams of the die assembly of the present invention.

[0048] Fig.16 It is a cross-sectional view of the die assembly of the present invention.

[0049] Fig.17 It is a cross-sectional view of the extrusion barrel in the present invention.

[0050] Fig.18 It is a shaping cylinder and a cross-sectional view thereof in the present invention.

[0051] Fig.19 It is a film and a cross-sectional view thereof in the present invention.

[0052] Fig. 20 It is a schematic diagram of the structure on the supporting cross bar in the present invention.

[0053] Fig.21 It is a cross-sectional view of the double-wall corrugated pipe product structure of the present invention.

[0054] Name of the label in the figure:

[0055] 100, double-layer extrusion assembly; 101, extruder; 102, extrusion barrel; 103, first extrusion slot; 104, second extrusion slot; 105, first heating layer; 106, second heating layer; 107, first feed port; 108, second feed port; 109, air delivery channel; 110, annular groove; 111, air inlet; 112, air delivery pipe; 113, air pump;

[0056] 200, first shaping assembly; 201, guide seat; 202, guide groove; 203, horizontal steering portion; 204, horizontal straight portion; 205, lifting steering portion; 206, sliding straight portion; 207, receiving groove; 208, negative pressure cooling assembly; 209, first sprocket; 210, second sprocket; 211, chain; 212, lug; 213, first lever; 214, round pin; 215, vortex spring; 216, swing limit block; 217, first synchronous shaft; 218, first motor;

[0057] 300, die assembly; 301, forming die; 302, first spiral groove; 303, first negative pressure hole; 304, spiral airway; 305, connecting groove; 306, first negative pressure tube; 307, guide rod; 308, ball head; 309, second lever; 310, telescopic rod; 311, outer sleeve; 312, first spring; 313, inner rod; 314, ball seat; 315, rolling ball;

[0058] 400, second shaping assembly; 401, shaping cylinder; 402, second spiral groove; 403, third spiral groove; 404, connecting hole; 405, film; 406, second negative pressure hole; 407, supporting cross bar; 408, first tripod; 409, first roller; 410, second tripod; 411, second roller; 412, round plate; 413, air extraction hole; 414, rubber ring plate; 415, supporting assembly; 416, first guide sleeve; 417, second spring; 418, push rod; 419, wheel seat ; 420, third roller; 421, rotating shaft; 422, first gear; 423, rotating seat; 424, sleeve; 425, second gear; 426, third gear; 427, rotating sleeve; 428, fourth gear; 429, fifth gear; 430, second motor; 431, sixth gear; 432, second synchronous shaft; 433, seventh gear; 434, eighth gear; 435, ninth gear; 436, first connecting pipe; 437, second connecting pipe; 438, second negative pressure pipe; 439, negative pressure pump;

[0059] 500, double-wall corrugated pipe; 501, inner pipe; 502, outer pipe. DETAILED DESCRIPTION

[0060] In order to make the purpose, technical solution and advantages of the present invention more clearly understood, the present invention is further described in detail below through embodiments and in conjunction with the accompanying drawings. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0061] The serial numbers assigned to the components herein, such as "first", "second", etc., are only used to distinguish the objects described and do not have any order or technical meaning. The "connection" and "coupling" mentioned in this application, unless otherwise specified, include direct and indirect connections (couplings). In the description of the present invention, it should be understood that the orientation or position relationship indicated by the terms "upper", "lower", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise", etc. are based on the orientation or position relationship shown in the accompanying drawings, which is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation to the present invention.

[0062] In the present invention, unless otherwise clearly specified and limited, a first feature being "above" or "below" a second feature may mean that the first and second features are in direct contact, or the first and second features are in indirect contact through an intermediate medium. Moreover, a first feature being "above", "above" or "above" a second feature may mean that the first feature is directly above or obliquely above the second feature, or simply means that the first feature is higher in level than the second feature. A first feature being "below", "below" or "below" a second feature may mean that the first feature is directly below or obliquely below the second feature, or simply means that the first feature is lower in level than the second feature.

[0063] like Figure 1-21 As shown, a double-wall corrugated plastic pipe forming device is used for forming a double-wall corrugated pipe 500, comprising:

[0064] The double-layer extrusion assembly 100 is used for continuously and synchronously extruding the inner tube 501 and the outer tube 502 of the double-wall corrugated tube 500 and blowing room temperature air between the inner tube 501 and the outer tube 502 .

[0065] The first shaping component 200 is used for shaping the corrugated outer tube 502; the first shaping component 200 includes two guide seats 201 symmetrically distributed on both sides of the outer tube 502, and the side wall of the guide seat 201 has a plurality of die assemblies 300 driven by the driving component and only gathered at the outer tube 502 to press and shape the outer tube 502 for translational movement along the annular guide groove 202, the die assembly 300 includes a semicircular molding die 301, the inner wall of the molding die 301 is provided with a first spiral groove 302, the wall surface of the first spiral is densely covered with first negative pressure holes 303 distributed along the spiral and connected to the first negative pressure tube 306 at the upper end of the outer side of the molding die 301, the first spiral grooves 302 of adjacent molding dies 301 on the same guide seat 201 are connected, and the first spiral grooves 302 of the docking molding dies 301 on the two guide seats 201 form a complete spiral.

[0066] The second shaping component 400 is used for supporting the moving inner tube 501 and the outer tube 502 from inside the inner tube 501 and shaping the inner tube 501; the second shaping component 400 includes a shaping cylinder 401 located in the inner tube 501 and having a smooth surface, the inner and outer walls of the shaping cylinder 401 are respectively provided with a second spiral groove 402 and a third spiral groove 403 connected by densely distributed connecting holes 404, the surface of the shaping cylinder 401 is coated with a film 405, and the film 405 is densely distributed with second negative pressure holes 406, and a supporting component 415 is provided in the middle of the shaping cylinder 401 for supporting and positioning the shaping cylinder 401 and driving the film 405 to move synchronously with the inner tube 501, and the supporting component 415 forms a negative pressure space in the shaping cylinder 401 to generate negative pressure in the second spiral groove 402 and the third spiral groove 403.

[0067] In a further embodiment, Figure 1 , 2As shown in , 3, and 17, the double-layer extrusion assembly 100 includes an extrusion barrel 102 installed on a bracket, and a first extrusion groove 103 and a second extrusion groove 104 are opened in the barrel wall of the extrusion barrel 102 to communicate with one end thereof, a first heating layer 105 is arranged in the large diameter wall surface of the first extrusion groove 103, and a second heating layer 106 is arranged in the small diameter wall surface of the second extrusion groove 104, and a plurality of air delivery channels 109 uniformly distributed in the circumferential direction and penetrating the two ends of the extrusion barrel 102 are opened in the barrel wall between the first extrusion groove 103 and the second extrusion groove 104, and the extrusion barrel The non-extrusion end of 102 is provided with an annular groove 110 connecting all the air supply channels 109, and the air inlet 111 on the annular groove 110 is connected to the air pump 113 on the outside of the extrusion barrel 102 through the air supply pipe 112. The wall surface of the extrusion barrel 102 is provided with a first feed port 107 and a second feed port 108 circumferentially 180 degrees apart, the first feed port 107 is connected to the first extrusion groove 103, the second feed port 108 is connected to the second extrusion groove 104, and the first feed port 107 and the second feed port 108 are respectively connected to the extrusion ports of the two extruders 101.

[0068] In a further embodiment, Fig.14 As shown, two annular guide grooves 202 distributed up and down are provided on the side wall of the guide seat 201, and the guide groove 202 consists of a horizontal turning portion 203, a horizontal straight portion 204, a lifting turning portion 205 and a return sliding straight portion 206. The horizontal turning portion 203 is located at the initial end of the shaping cylinder 401, the horizontal straight portion 204 is opposite to the shaping cylinder 401, the lifting turning portion 205 is located at the end of the shaping cylinder 401, and the end of the lifting turning portion 205 is connected to the beginning of the horizontal turning portion 203 through the return sliding straight portion 206.

[0069] In a further embodiment, Fig.10 , 11, 12, 15, and 16, a spiral air channel 304 corresponding to the first spiral groove 302 is provided in the wall surface of the molding die 301, and the spiral air channel 304 is connected to the first spiral groove 302 through the first negative pressure hole 303. A connecting groove 305 connecting the spiral air channel 304 and the first negative pressure tube 306 is provided in the molding die 301. Two guide rods 307 corresponding to the guide groove 202 are provided on the outer arc wall of the molding die 301. The end of the guide rod 307 is provided with a ball head 308, and the ball head 308 slides in the guide groove 20 2, two telescopic rods 310 distributed along the axis of the forming mold 301 are arranged on the outer arc wall of the forming mold 301, and the telescopic rod 310 is composed of an outer sleeve 311 fixed to the forming mold 301 and an inner rod 313 sliding in the outer sleeve 311, and a first spring 312 driving the inner rod 313 to extend and retract is arranged in the outer sleeve 311, and a ball seat 314 is arranged at the end of the inner rod 313, and a rolling ball 315 is arranged in the ball seat 314 to abut against the side wall of the guide seat 201, and two second levers 309 distributed up and down are arranged on the outer arc wall of the forming mold 301.

[0070] In a further embodiment, Fig. 9 , 10 11, the driving assembly includes two first sprockets 209 corresponding to the second levers 309 on the molding die 301 and two second sprockets 210 corresponding to the first sprockets 209. The first sprockets 209 are connected to the corresponding second sprockets 210 through chains 211. The first sprockets 209, the first chains 211 and the corresponding chains 211 are located in the receiving grooves 207 on the guide seat 201. The first sprockets 209 correspond to the horizontal turning portion 203, the second sprockets 210 correspond to the horizontal straight portion 204, and the chains 211 are all There are a number of evenly spaced ears 212, and a first lever 213 cooperating with a second lever 309 is hinged on the ear 212 through a round pin 214. The round pin 214 is fixedly connected to the first lever 213, and a vortex spring 215 is connected between the round pin 214 and the ear 212. The first lever 213 is provided with a swing limit block 216 for limiting its swing direction. The two first sprockets 209 are installed on a first synchronization shaft 217, and the first synchronization shaft 217 is installed in the guide seat 201. The first synchronization shaft 217 is connected to the output shaft of the first motor 218 on the bracket.

[0071] In a further embodiment, Figure 3 , 4As shown in Figures 5, 8 and 20, the support assembly 415 includes a support cross bar 407, and the support cross bar 407 is suspended in the middle of the shaping cylinder 401. The annular groove 110 end of the support cross bar 407 is fixed to the bracket, and the two ends of the support cross bar 407 are respectively installed with a first tripod 408, and the three legs of the first tripod 408 are all installed with a first roller 409 that abuts against the end of the film 405 and positions the shaping cylinder 401.

[0072] In a further embodiment, Fig. 20 As shown, the supporting crossbar 407 is provided with a plurality of second tripods 410 evenly distributed along its axial direction, and the three legs of the second tripod 410 are all equipped with second rollers 411 that support the inner wall of the film 405 .

[0073] In a further embodiment, Fig. 20 As shown, two circular plates 412 are installed on the supporting cross bar 407, and a rubber ring plate 414 is provided at the edge of the circular plate 412 to seal with the film 405. The second spiral groove 402 and the third spiral groove 403 on the shaping cylinder 401 are located in the range between the two circular plates 412. An exhaust hole 413 is opened on the circular plate 412 located on the side of the ring groove 110. The exhaust hole 413 is connected to the second connecting tube 437 through the first connecting tube 436. The second connecting tube 437 is connected to the negative pressure pump 439 on the outer wall of the extrusion cylinder 102 through the second negative pressure tube 438.

[0074] In a further embodiment, Figure 6 , 7As shown in Figures 20 and 21, three first guide sleeves 416 uniformly distributed in the circumferential direction are arranged on the support cross bar 407, a push rod 418 is radially slidable in the first guide sleeve 416 along the shaping cylinder 401, a wheel seat 419 is installed at the exposed end of the push rod 418, a third roller 420 for squeezing the film 405 is installed in the wheel seat 419, a second spring 417 driving the push rod 418 to move outward is arranged in the first guide sleeve 416, a rotating shaft 421 parallel to the push rod 418 is installed on the wheel seat 419, a shaft sleeve 424 is slidably arranged on the rotating shaft 421, the shaft sleeve 424 is rotatably arranged in the rotating seat 423 on the first guide sleeve 416, a second synchronous shaft 432 is installed on the wheel seat 419, and the second synchronous shaft 432 is installed on the wheel seat 419. A sixth gear 431 and a seventh gear 433 are mounted on the step shaft 432, the sixth gear 431 meshes with the first gear 422 mounted on the rotating shaft 421, the seventh gear 433 meshes with the eighth gear 434 mounted on the wheel seat 419, the eighth gear 434 meshes with the ninth gear 435 mounted on the shaft where the third roller 420 is located, a rotating sleeve 427 is rotatably set on the support crossbar 407, the rotating sleeve 427 is mounted with a third gear 426 and a fourth gear 428, the third gear 426 meshes with the second gear 425 on the shaft sleeve 424, the fourth gear 428 meshes with the fifth gear 429 on the output shaft of the second motor 430, and the second motor 430 is mounted on the bracket.

[0075] The connection method of double-wall corrugated pipe 500 is:

[0076] S1, the inner tube 501 and the outer tube 502 are synchronously and continuously extruded from the second extrusion groove 104 and the first extrusion groove 103 of the extrusion barrel 102, and the air supply channel 109 on the extrusion barrel 102 blows room temperature air into the space between the inner tube 501 and the outer tube 502 for cooling, so as to avoid adhesion between the inner tube 501 and the outer tube 502 in a soft state. At the same time, the film 405 moves synchronously with the inner tube 501 under the drive of the three third rollers 420, and the negative pressure generated by the second negative pressure hole 406 on the film 405 adsorbs the inner tube 501 and shapes it.

[0077] S2. With the movement of the inner tube 501 and the outer tube 502, the die assembly 300 on the two guide seats 201 applies pressure to the outer tube 502, and the outer tube 502 and the inner tube 501 are bonded together. At the same time, the die assembly 300 absorbs the outer tube 502 through the first negative pressure hole 303 on its inner wall to form a spiral hollow between the inner tube 501 and the outer tube 502. The air blown between the inner tube 501 and the outer tube 502 by the air supply channel 109 moves forward through the spiral hollow space, thereby achieving effective cooling of the inner tube 501 and the outer tube 502 that have been bonded.

[0078] A negative pressure cooling assembly 208 is disposed on the top of the guide seat 201 to provide negative pressure to the first negative pressure pipe 306 in the moving die assembly 300 and to transport cooling air into the first spiral groove 302 .

[0079] The present invention extrude the inner tube 501 and the outer tube 502 of the double-wall corrugated tube 500 simultaneously through the extrusion barrel 102 and perform synchronous contact bonding on the two layers. Therefore, the product strength of the double-wall corrugated tube 500 of the present invention is higher than the strength of the double-wall corrugated tube 500 in which the two layers are formed separately and then glued. In addition, the double-wall corrugated tube 500 of the present invention has fewer molding steps and higher production efficiency. The present invention blows room temperature air between the inner tube 501 and the outer tube 502 extruded simultaneously through the air supply channel 109 located between the first extrusion groove 103 and the second extrusion groove 104 on the extrusion barrel 102, so that there will be no local adhesion between the outer tube 502 and the inner tube 501 before being pressurized by the first molding component 200, ensuring that there will be no local continuous solid situation between the outer tube 502 and the inner tube 501 after the outer tube 502 and the inner tube 501 are pressurized and molded by the first molding component 200, so that the part between the outer tube 502 and the inner tube 501 that needs to be hollow remains in a hollow state, thereby reducing the material consumption and the weight of the final product while maintaining the same strength, thereby reducing the material cost of the double-wall corrugated tube 500. The surface film 405 of the sizing cylinder for shaping and supporting the inner tube 501 in the present invention moves synchronously with the inner tube 501 under the drive of the support assembly 415, ensuring the smoothness of the inner wall of the inner tube 501. The negative pressure generated by the second spiral groove 402 and the third spiral groove 403 connected on the inner and outer walls of the shaping cylinder 401 in the second shaping assembly 400 and the second negative pressure hole 406 on the film 405 can promote the rapid shaping of the inner tube 501. At the same time, the air delivery channel 109 located between the first extrusion groove 103 and the second extrusion groove 104 on the extrusion cylinder 102 blows normal temperature air between the inner tube 501 and the outer tube 502, which effectively cools the outer wall of the inner tube 501 and the inner wall of the outer tube 502. In the present invention, the die assemblies 300 in the two first molding assemblies 200 located on both sides of the molding cylinder 401 are concentrated on the pressure-applying side of the double-wall corrugated tube 500. After completing the pressure-applying to the double-wall corrugated tube 500, the die assemblies 300 automatically slide to the initial pressure end position on the guide seat 201 and supplement the die assemblies 300 on the pressure-applying side of the double-wall corrugated tube 500 under the drive of the support assembly 415, thereby effectively reducing the number of die assemblies 300 and effectively reducing equipment costs.

[0080] The operation process of the present invention is as follows:

[0081] In the initial state, the die assemblies 300 on the two guide seats 201 in the first shaping assembly 200 gather at the horizontal straight portion 204, the horizontal turning portion 203 and the lifting turning portion 205 of the guide groove 202. The first lever 213 on the chain 211 is in an effective state of shifting the second lever 309 on the corresponding die assembly 300, the vortex spring 215 is in a compressed state, and the swing limit block 216 is in contact with the lug 212.

[0082] When the double-wall corrugated pipe 500 is produced by the present invention, the two first motors 218 and the second motor 430 are started, and the two first motors 218 drive the corresponding two first sprockets 209 to move through the corresponding first synchronous shafts 217, and the two sprockets drive the die assembly 300 to move from the horizontal turning part 203 to the horizontal straight part 204 through the interaction between the first lever 213 thereon and the second lever 309 on the die assembly 300 at the corresponding position, and then move from the horizontal straight part 204 to the lifting turning part 205, and move to the die assembly at the end of the lifting turning part 205. Under the action of its own weight, the component 300 automatically and quickly slides along the sliding straight portion 206 to the initial end of the horizontal turning portion 203. The second lever 309 on the die assembly 300 that slides to the initial end of the horizontal turning portion 203 overcomes the vortex spring 215 corresponding to the corresponding first lever 213 and passes over the first lever 213. After the second lever 309 on the die assembly 300 passes over the first lever 213, the first lever 213 swings back and resets under the action of the vortex spring 215 and drives the die assembly 300 to move horizontally from the horizontal turning portion 203 to the horizontal straight portion 204 through the second lever 309 driven by the chain 211.

[0083] The die assembly 300 reaching the horizontal straight portion 204 and the die assembly 300 reaching the horizontal straight portion 204 on the opposite side guide seat 201 are spliced ​​one by one to form a complete cylinder with a first spiral groove 302 on the inner wall and continue to move forward synchronously driven by the chain 211.

[0084] During the movement of the die assembly 300, the two extruders 101 are started, and the two extruders 101 squeeze molten materials into the first extrusion groove 103 and the second extrusion groove 104 respectively, and the first extrusion groove 103 and the second extrusion groove 104 respectively extrude the outer tube 502 and the inner tube 501 of the double-wall corrugated tube 500, and the first heating layer 105 and the second heating layer 106 respectively heat the materials in the first extrusion groove 103 and the second extrusion groove 104 to maintain their fluidity. At the same time, the air pump 113 blows room temperature air between the extruded inner tube 501 and the outer tube 502 through the air supply pipe 112, the annular groove 110 and the air supply channel 109, so that the inner tube 501 and the outer tube 502 can be cooled and will not be adhered before the outer tube 502 is pressed and formed.

[0085] When the die assembly 300 moves along the guide groove 202, the two telescopic rods 310 on the die assembly 300 and the rolling balls 315 at their ends can prevent the die assembly 300 from swinging sideways and always keep its center line tangent to its movement trajectory, ensuring that the die assembly 300 can smoothly complete the joint connection with the corresponding die assembly 300 on the opposite guide seat 201 after reaching the horizontal straight portion 204, and then apply pressure to the entering outer tube 502, so that the outer tube 502 forms a spiral hollow under the adsorption action of the first spiral groove 302 on the inner wall of the die assembly 300, and at the same time, the outer tube 502 and the inner tube 501 are integrally bonded, and the bonding portion is in the shape of a spiral strip.

[0086] During the process of synchronous and continuous motion forming of the inner tube 501 and the outer tube 502, the second motor 430 drives the three second gears 425 to rotate synchronously at a constant speed through the fifth gear 429, the fourth gear 428, the rotating sleeve 427, and the third gear 426. The three second gears 425 respectively drive the corresponding third rollers 420 to rotate through the corresponding shaft sleeve 424, the rotating shaft 421, the first gear 422, the sixth gear 431, the second synchronous shaft 432, the seventh gear 433, the eighth gear 434, and the ninth gear 435. The three third rollers 420 simultaneously rotate The film 405 is driven to slide relative to the shaping cylinder 401. The movement speed and direction of the film 405 are consistent with the movement of the inner tube 501. The third roller 420, under the action of the second spring 417, presses the film 405 so that there is sufficient friction between the third roller 420 and the film 405, so that the film 405 can effectively move relative to the shaping cylinder 401. The film 405 that moves consistently with the inner tube 501 supports the moving inner tube 501, and since there is no relative movement between the two, the inner wall of the inner tube 501 remains smooth.

[0087] The first rollers 409 on the two first tripods 408 effectively position the shaping cylinder 401 to prevent the shaping cylinder 401 from deflecting.

[0088] During the process of synchronous movement support of the shaping cylinder 401 and the film 405 on the moving inner tube 501, the negative pressure pump 439 extracts the air in the space between the two circular plates 412 in the shaping cylinder 401 through the second negative pressure pipe 438, the second connecting pipe 437 and the first connecting pipe 436, so that negative pressure is generated in the space between the two circular plates 412. The negative pressure in the space between the two circular plates 412 generates negative pressure on the inner tube 501 side of the film 405 through the second negative pressure hole 406 on the film 405 and the second spiral groove 402, the connecting hole 404 and the third spiral groove 403 on the shaping cylinder 401, thereby adsorbing the inner tube 501. The adsorption support of the inner tube 501 by the film 405 finally completes the shaping of the inner tube 501.

[0089] During the movement of the film 405 , the rubber ring plates 414 at the edges of the two circular plates 412 maintain contact and sealing with the film 405 , so that the space between the two circular plates 412 is always in a closed state.

[0090] The second spiral groove 402 and the third spiral groove 403 connected by the spirally distributed connecting holes 404 on the inner and outer walls of the shaping cylinder 401 can enable the air in the second spiral groove 402 and the third spiral groove 403 to form an air flow along the spiral direction under the action of negative pressure, which can effectively cool the film 405 on the side of the inner layer tube 501 to a certain extent, thereby facilitating the rapid shaping of the inner layer tube 501.

Claims

1. A double-wall corrugated plastic pipe forming equipment, used for forming double-wall corrugated pipes, characterized in that: include: Double-layer extrusion assembly, used for continuously and synchronously extruding the inner layer and outer layer of the double-wall corrugated pipe and blowing normal temperature air between the inner layer and the outer layer; A first shaping component is used for shaping the corrugated outer tube; the first shaping component comprises two guide seats symmetrically distributed on both sides of the outer tube, a plurality of die assemblies driven by a driving component and gathered only at the outer tube for translational movement along the annular guide groove on the side wall of the guide seat and pressurizing the outer tube to shape the outer tube, the die assembly comprises a semicircular forming die, a first spiral groove is provided on the inner wall of the forming die, first negative pressure holes are densely distributed along the spiral and connected to the first negative pressure tube at the upper end of the outer side of the forming die on the wall surface of the first spiral, the first spiral grooves of adjacent forming dies on the same guide seat are connected, and the first spiral grooves of the butted forming dies on the two guide seats form a complete spiral; A second shaping component is used to support the moving inner tube and outer tube from inside the inner tube and to shape the inner tube; the second shaping component includes a shaping cylinder located in the inner tube and having a smooth surface, the inner and outer walls of the shaping cylinder are respectively provided with a second spiral groove and a third spiral groove connected by densely distributed connecting holes, the surface of the shaping cylinder is covered with a film, the film is densely distributed with second negative pressure holes, a supporting component is provided in the middle of the shaping cylinder for supporting and positioning the shaping cylinder and driving the film and the inner tube to move synchronously, the supporting component forms a negative pressure space in the shaping cylinder that causes the second spiral groove and the third spiral groove to generate negative pressure; The double-layer extrusion assembly includes an extrusion barrel installed on a bracket, a first extrusion groove and a second extrusion groove connected to one end of the extrusion barrel are provided in the barrel wall of the extrusion barrel, a first heating layer is provided in the large-diameter wall of the first extrusion groove, and a second heating layer is provided in the small-diameter wall of the second extrusion groove, a plurality of air supply channels uniformly distributed circumferentially and passing through both ends of the extrusion barrel are provided in the barrel wall between the first extrusion groove and the second extrusion groove, an annular groove connected to all air supply channels is provided at the non-extrusion end of the extrusion barrel, an air inlet on the annular groove is connected to an air pump outside the extrusion barrel through an air supply pipe, a first feed port and a second feed port 180 degrees apart in the circumferential direction are provided on the wall of the extrusion barrel, the first feed port is connected to the first extrusion groove, the second feed port is connected to the second extrusion groove, and the first feed port and the second feed port are respectively connected to the extrusion ports of two extruders.

2. A double-wall corrugated plastic pipe forming equipment according to claim 1, characterized in that: Two annular guide grooves distributed up and down are provided on the side wall of the guide seat, and the guide groove consists of a horizontal turning part, a horizontal straight part, a lifting turning part and a return sliding straight part. The horizontal turning part is located at the initial end of the shaping cylinder, and the horizontal straight part is opposite to the shaping cylinder. The lifting turning part is located at the end of the shaping cylinder, and the end of the lifting turning part is connected to the starting end of the horizontal turning part through the return sliding straight part.

3. The double-wall corrugated plastic pipe forming equipment according to claim 2, characterized in that: A spiral air channel corresponding to the first spiral groove is provided in the wall surface of the forming mold, and the spiral air channel is connected with the first spiral groove through the first negative pressure hole. A connecting groove connecting the spiral air channel and the first negative pressure tube is provided in the forming mold. Two guide rods corresponding to the guide grooves are provided on the outer arc wall of the forming mold, and ball heads are provided at the ends of the guide rods. The ball heads slide in the guide grooves. Two telescopic rods distributed along the axis thereof are provided on the outer arc wall of the forming mold. The telescopic rods are composed of an outer sleeve fixed to the forming mold and an inner rod sliding in the outer sleeve. A first spring for driving the inner rod to telescope is provided in the outer sleeve. A ball seat is provided at the end of the inner rod, and a rolling ball that abuts against the side wall of the guide seat is provided in the ball seat. Two second levers distributed up and down are provided on the outer arc wall of the forming mold.

4. The double-wall corrugated plastic pipe forming equipment according to claim 1, characterized in that: The drive assembly includes two first sprockets corresponding to the second levers on the forming mold and two second sprockets corresponding to the first sprockets respectively. The first sprocket is connected to the corresponding second sprocket through a chain. The first sprocket, the first chain and the corresponding chain are located in the accommodating groove on the guide seat. The first sprocket corresponds to the horizontal turning part, and the second sprocket corresponds to the horizontal straight part. A plurality of ears are evenly distributed on the chain. The ear is hinged with a first lever cooperating with the second lever through a round pin. The round pin is fixedly connected to the first lever, and a vortex spring is connected between the round pin and the ear. The first lever is provided with a swing limit block to limit its swing direction. The two first sprockets are installed on the first synchronous shaft, the first synchronous shaft is installed in the guide seat, and the first synchronous shaft is connected to the output shaft of the first motor on the bracket.

5. The double-wall corrugated plastic pipe forming equipment according to claim 1, characterized in that: The support assembly includes a support cross bar, which is suspended in the middle of the shaping cylinder. The annular groove end of the support cross bar is fixed on the bracket. The two ends of the support cross bar are respectively installed with a first tripod, and the three legs of the first tripod are each installed with a first roller that abuts against the end of the film and positions the shaping cylinder.

6. The double-wall corrugated plastic pipe forming equipment according to claim 5, characterized in that: The supporting crossbar is provided with a plurality of second tripods evenly distributed along its axial direction, and the three legs of the second tripods are all equipped with second rollers supporting the inner wall of the film.

7. The double-wall corrugated plastic pipe forming equipment according to claim 5, characterized in that: Two circular plates are installed on the supporting cross bar, and rubber ring plates that cooperate with the film seal are arranged at the edges of the circular plates. The second spiral groove and the third spiral groove on the shaping cylinder are located between the two circular plates. An air suction hole is opened on the circular plate located on the side of the ring groove. The air suction hole is connected to the second connecting pipe through the first connecting pipe, and the second connecting pipe is connected to the negative pressure pump on the outer wall of the extrusion cylinder through the second negative pressure pipe.

8. The double-wall corrugated plastic pipe forming equipment according to claim 5, characterized in that: The supporting cross bar is provided with three first guide sleeves evenly distributed in the circumference, and a push rod is radially slidable in the first guide sleeve along the shaping cylinder, and a wheel seat is installed at the exposed end of the push rod, and a third roller for extruding the film is installed in the wheel seat, and a second spring for driving the push rod to move outward is arranged in the first guide sleeve, and a rotating shaft parallel to the push rod is installed on the wheel seat, and a shaft sleeve is slidably arranged on the rotating shaft, and the shaft sleeve is rotatably arranged in the rotating seat on the first guide sleeve, and a second synchronous shaft is installed on the wheel seat, and a sixth gear and a seventh gear are installed on the second synchronous shaft, and the sixth gear is meshed with the first gear installed on the rotating shaft, and the seventh gear is meshed with the eighth gear installed on the wheel seat, and the eighth gear is meshed with the ninth gear installed on the shaft where the third roller is located, and a rotating sleeve is rotatably arranged on the supporting cross bar, and a third gear and a fourth gear are installed on the rotating sleeve, and the third gear is meshed with the second gear on the shaft sleeve, and the fourth gear is meshed with the fifth gear on the output shaft of the second motor, and the second motor is installed on the bracket.

9. The double-wall corrugated pipe connection method of the double-wall corrugated plastic pipe forming equipment according to claim 1, characterized in that: The connection method of double-wall corrugated pipe is: S1, the inner tube and the outer tube are synchronously and continuously extruded from the second extrusion groove and the first extrusion groove of the extruder, and the air supply channel on the extruder blows room temperature air to the space between the inner tube and the outer tube for cooling, so as to avoid the inner tube and the outer tube in a soft state from adhering to each other. At the same time, the film moves synchronously with the inner tube under the drive of the three third rollers, and the negative pressure generated by the second negative pressure hole on the film adsorbs the inner tube and shapes it; S2. With the movement of the inner tube and the outer tube, the die assemblies on the two guide seats apply pressure to the outer tube, and the outer tube and the inner tube are bonded together. At the same time, the die assembly adsorbs the outer tube through the negative pressure generated by the first negative pressure hole on the first spiral groove on its inner wall, so that a spiral hollow is formed between the inner tube and the outer tube. The air blown between the inner tube and the outer tube by the air supply duct moves forward through the spiral hollow space, thereby achieving effective cooling of the bonded inner tube and the outer tube.

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