CN114407325A - Double-layer plastic pipe extrusion molding production line and its molding process - Google Patents

Abstract

The invention relates to the technical field of plastic pipe forming equipment, in particular to an extrusion forming production line of a double-layer plastic pipe and a forming process thereof, which are characterized in that: including the extruder that sets gradually, vacuum design and cooling body, the end fixed mounting that extrudes of extruder has double-deck extrusion moulding mould, double-deck extrusion moulding mould is used for the shaping to have the outer tube, the double-deck plastic tubing of inner tube and a plurality of strengthening rib, the outer tube, be formed with the lumen between inner tube and two adjacent strengthening ribs, be connected with on the double-deck extrusion moulding mould and be used for blowing towards the lumen in order to avoid outer tube inner wall and the mechanism of blowing that the inner tube outer wall bindes mutually, vacuum design and cooling body are used for playing vacuum design and cooling action simultaneously to outer tube and inner tube after the shaping. The double-layer plastic pipe is novel in integral structure, more flexible in integral production and convenient to manufacture, a new process is adopted, the integral lightweight of the double-layer plastic pipe is effectively ensured, and the integral manufacturing cost and the material cost can be effectively saved.

Description

Double-layer plastic pipe extrusion molding production line and its molding process

technical field

The invention relates to the technical field of plastic pipe forming equipment, in particular to a double-layer plastic pipe extrusion forming production line and a forming process thereof.

Background technique

Plastic products are a general term for household and industrial products made of plastic as the main raw material, including injection molding, extrusion and other products with plastic as raw material. Plastic is a kind of plastic synthetic polymer material. Synthetic rubber and synthetic fibers form the three indispensable synthetic materials in daily life. Specifically, plastics are made of natural or synthetic resin as the main component, and various additives are added. Under certain conditions of temperature and pressure, plastic can be molded into a certain Shape, a material that keeps the shape unchanged at room temperature, some existing plastic products, such as the plastic rubber tube in the middle of the transparent tape, are usually injection-molded and have a structure with an outer ring and an inner ring. There is also a connecting ring between the outer ring and the inner ring, so that the outer ring and the inner ring are connected as a whole, and in order to save the material cost of the plastic cartridge, there are usually a plurality of through holes on the connecting ring, but Even so, the material cost and the manufacturing cost are still relatively high when the injection molding process is used.

SUMMARY OF THE INVENTION

The technical problem to be solved by the present invention is to provide a novel overall structure, the overall production is more flexible, the production is convenient, and a new process is adopted, which can effectively ensure the overall lightweight of the double-layer plastic pipe, and can effectively save the overall production cost and Material cost double-layer plastic pipe extrusion molding production line and its molding process.

In order to solve the above-mentioned technical problems, the technical scheme adopted in the present invention is as follows: a double-layer plastic pipe extrusion molding production line, including an extruder, a vacuum setting and a cooling mechanism arranged in sequence, and the extrusion end of the extruder is fixedly installed with a double-layer plastic pipe. Layer extrusion molding die, the double-layer extrusion molding die is used to form a double-layer plastic tube with an outer tube, an inner tube and a plurality of reinforcing ribs, and a tube is formed between the outer tube, the inner tube and the two adjacent reinforcing ribs. The cavity, the double-layer extrusion molding die is connected with a blowing mechanism for blowing air into the cavity to prevent the inner wall of the outer tube from adhering to the outer wall of the inner tube. The vacuum setting and cooling mechanism is used for forming the outer tube and inner tube. The tube plays the role of vacuum setting and cooling at the same time.

Further, the double-layer extrusion molding die is provided with a first extrusion channel for molding the outer tube, a second extrusion channel for molding the inner tube, and a plurality of notches for molding the reinforcing ribs. The outflow channel communicates with the second extrusion channel through the notch.

Further, the double-layer extrusion molding die includes an outer mold body, a core mold body and a hollow mold body, the outer mold body is fixedly connected with the extruder and is sleeved on the core mold body, and the hollow mold body includes an inner ring arranged inside and outside sequentially. and the outer ring, the inner ring and the outer ring are fixedly connected together by a plurality of connecting blocks, the outer ring is connected to the outer mold body, and one end of the core mold body is inserted into the inner ring, and the outer ring and the inner ring are between the outer ring and the inner ring. A first extrusion flow channel is formed, a second extrusion flow channel is formed between the inner ring and the core mold body, and a plurality of notches are uniformly arranged along the circumferential direction of the inner ring and are arranged on the inner ring.

Further, an extrusion flow channel is also formed between the outer mold body and the core mold body, and both the first extrusion flow channel and the second extrusion flow channel communicate with the extrusion flow channel.

Further, the blowing mechanism includes a main blowing pipe for conveying gas, a plurality of blowing passages that can be one-to-one corresponding to the cavity are provided on the double-layer extrusion molding die, and the main blowing pipe passes through a plurality of blowing branches. The pipes are communicated with a plurality of air blowing channels one by one.

Further, the vacuum setting and cooling mechanism includes a support frame, an outer setting sleeve, an inner setting sleeve, a vacuum setting component and a circulating cooling component. The outer setting sleeve is fixedly installed on the support frame and used to cover the outer side of the outer tube. The extrusion molding die is connected and used to cover the inner side of the inner tube. The vacuum setting component and the circulating cooling component are arranged in sequence along the conveying direction of the double-layer plastic tube. There are several inner adsorption holes, the vacuum forming component is connected with the outer adsorption hole and the inner adsorption hole and plays the role of vacuum forming on the outer tube and the inner tube.

Further, the vacuum setting assembly includes a vacuum pump, an outer vacuum annular cover and an inner vacuum annular cover, the vacuum pump is fixedly installed on the support frame, the outer vacuum annular cover is fixedly sleeved on the outer side of the outer shaping sleeve and covers a number of outer adsorption holes, and the inner vacuum annular cover is The fixed sleeve is arranged on the inner side of the inner setting sleeve and covers a number of inner adsorption holes. The vacuum pump is communicated with the outer vacuum annular cover through the outer vacuum pipe, and the vacuum pump is communicated with the inner vacuum annular cover through the inner vacuum pipe. The first connecting channel through which the inner vacuum tube passes.

Further, the circulating cooling assembly includes a water pump, a water tank, a cooling fin, an outer cooling annular cover and an inner cooling annular cover. The outer side of the sleeve, the inner cooling annular cover is fixedly sleeved on the inner side of the inner shaping sleeve, the water inlet end of the water pump is communicated with the water tank, the water outlet end of the water pump is communicated with the outer cooling annular cover through the outer water inlet pipe, and is connected with the inner cooling ring through the inner water inlet pipe. The cover is connected, the outer cooling annular cover is connected with the cooling fins through the outer water outlet pipe, the inner cooling annular cover is connected with the cooling fins through the inner water outlet pipe, and the cooling fins are connected with the water tank. There are two second connection channels through which the inner water inlet pipe and the inner water outlet pipe can pass through respectively.

Further, the circulating cooling assembly further includes a filter box, and the water inlet end of the water pump is communicated with the water tank through the filter box.

A molding process of a double-layer plastic pipe extrusion molding production line, which adopts any one of the above-mentioned double-layer plastic pipe extrusion molding production lines for molding, comprises the following steps:

Step 1: extrusion molding, the extruder extrudes a double-layer plastic tube with an outer tube, an inner tube and several reinforcing ribs through a double-layer extrusion molding die;

Step 2: Blow air to prevent sticking. During the extrusion molding process of the double-layer plastic tube, blow air through the lumen formed by the outer tube, the inner tube and the reinforcing ribs to avoid the inner wall of the outer tube and the outer wall of the inner tube. glue;

Step 3: vacuum forming, by vacuum forming and adsorbing the formed outer tube and inner tube at the same time;

Step 4: Circulating cooling, by simultaneously cooling the outer tube and the inner tube after being shaped.

It can be seen from the above description that the overall structure of the double-layer plastic pipe extrusion molding production line provided by the present invention is novel. , and then the double-layer plastic tube can be cut into corresponding lengths according to actual needs, and plastic products such as plastic cartridges can be obtained. The overall production is more flexible and convenient to manufacture. The overall lightweight of the tube can effectively save the overall production cost and material cost.

Description of drawings

FIG. 1 is a schematic three-dimensional structure diagram of the double-layer plastic pipe extrusion molding production line of the present invention.

FIG. 2 is a partial enlarged schematic view of the position A in FIG. 1 .

FIG. 3 is a schematic structural diagram of the double-layer plastic pipe extrusion molding production line of the present invention.

FIG. 4 is a partial enlarged schematic view of B in FIG. 3 .

FIG. 5 is a partial enlarged schematic view of C in FIG. 3 .

Fig. 6 is a front view of a double-layer extrusion die.

FIG. 7 is a schematic cross-sectional view along the D-D direction in FIG. 6 .

FIG. 8 is a partial enlarged schematic view of the position F in FIG. 7 .

FIG. 9 is a schematic cross-sectional view along the direction E-E in FIG. 6 .

Schematic diagram of the three-dimensional structure of the hollow phantom in FIG. 10 .

Figure 11 is a schematic structural diagram of a double-layer plastic pipe.

In the figure: 1-extruder; 2-vacuum setting and cooling mechanism; 21-support frame; 22-external setting sleeve; 221-external adsorption hole; 23-internal setting sleeve; 231-internal adsorption hole; 24-vacuum setting Component; 241-vacuum pump; 242-outer vacuum annular cover; 243-inner vacuum annular cover; 244-outer vacuum tube; 245-inner vacuum tube; 25-circulating cooling assembly; 251-water pump; 252-water tank; 253-radiating fins; 254-outer cooling ring cover; 255-inner cooling ring cover; 2561-outer water inlet pipe; 2562-inner water inlet pipe; 2571-outer water outlet pipe; 2572-inner water outlet pipe; 258-filter box; 3-double layer extrusion mould 31-external mold body; 32-core mold body; 33-hollow mold body; 331-inner ring; 3311-notch; 332-outer ring; 2-extrusion channel; 36-extrusion channel; 37-air blowing channel; 38-first connecting channel; 39-second connecting channel; 4-air blowing mechanism; 41-air blowing main pipe; 42-air blowing Branch pipe; 5-double-layer plastic pipe; 51-outer pipe; 52-inner pipe; 53-reinforcing rib; 54-lumen.

Detailed ways

The present invention will be further described below through specific embodiments.

As shown in Figures 1 to 11, the double-layer plastic pipe extrusion molding production line of the present invention includes an extruder 1, a vacuum setting and cooling mechanism 2 arranged in sequence, and the extrusion end of the extruder 1 is fixed A double-layer extrusion molding die 3 is installed, and the double-layer extrusion molding die 3 is used for molding a double-layer plastic pipe 5 having an outer pipe 51, an inner pipe 52 and a plurality of reinforcing ribs 53. A lumen 54 is formed between the inner tube 52 and the two adjacent reinforcing ribs 53, and the double-layer extrusion molding die 3 is connected to blow air into the lumen 54 to avoid the The blowing mechanism 4 in which the inner wall of the outer tube 51 and the outer wall of the inner tube 52 are bonded together, and the vacuum setting and cooling mechanism 2 is used to simultaneously perform vacuum setting and cooling effect.

The double-layer plastic tube 5 with the outer tube 51, the inner tube 52 and the plurality of reinforcing ribs 53 is integrally fabricated by extrusion molding, and the overall structural strength is good, and then the double-layer plastic tube 5 can be cut into corresponding lengths according to actual needs , and obtain plastic products such as plastic cartridges, the overall production is more flexible and convenient to manufacture, in addition, due to the adoption of a new process, the overall lightweight of the double-layer plastic tube 5 can be effectively ensured, and the overall production cost can be effectively saved. Material costs.

As shown in FIG. 8 and FIG. 10 , specifically, the double-layer extrusion molding die 3 is provided with a first extrusion flow channel 34 for molding the outer tube 51 , and a first extrusion channel 34 for molding the inner tube 52 . Two extrusion channels 35 and a plurality of notches 3311 for forming the reinforcing ribs 53 , the first extrusion channel 34 communicates with the second extrusion channel 35 through the gaps 3311 , so as to facilitate extrusion A double-layer plastic tube 5 having the outer tube 51 , the inner tube 52 and a plurality of the reinforcing ribs 53 is formed.

In addition, the number of the reinforcing ribs 53 can be set according to actual production requirements. Preferably, the number of the reinforcing ribs 53 is 4-12, and correspondingly, the number of the notches 3311 is also 4-12.

As shown in FIG. 6 to FIG. 10 , specifically, the double-layer extrusion molding die 3 includes an outer mold body 31 , a core mold body 32 and a hollow mold body 33 , and the outer mold body 31 is connected to the extruder 1 . It is fixedly connected and sleeved on the core mold body 32. The hollow mold body 33 includes an inner ring 331 and an outer ring 332 which are arranged in sequence inside and outside. The inner ring 331 and the outer ring 332 are connected by multiple connections. The block 333 is fixedly connected as a whole, the outer ring 332 is connected to the outer mold body 31 and one end of the core mold body 32 is inserted into the inner ring 331, and the outer ring 332 is connected to the inner ring 331. The first extrusion flow channel 34 is formed between the rings 331, the second extrusion flow channel 35 is formed between the inner ring 331 and the core mold body 32, and a plurality of the notches 3311 are formed along the The inner ring 331 is uniformly arranged in the circumferential direction and arranged on the inner ring 331 .

As shown in FIG. 7 and FIG. 9 , in addition, an extrusion flow channel 36 is formed between the outer mold body 31 and the core mold body 32 , and the first extrusion flow channel 34 is connected to the second extrusion flow channel 34 . The outflow channels 35 are all communicated with the extrusion flow channel 36 , and through the arrangement of the extrusion flow channel 36 , it is convenient for the raw materials extruded by the extruder 1 to enter better through the extrusion flow channel 36 . Inside the first extrusion flow channel 34 and the second extrusion flow channel 35 .

As shown in FIG. 4 and FIG. 10 , specifically, the blowing mechanism 4 includes a blowing main pipe 41 for conveying gas, and the double-layer extrusion molding die 3 is provided with a plurality of 54 One-to-one corresponding blowing passages 37, the blowing main pipe 41 communicates with the plurality of blowing passages 37 one by one through a plurality of blowing branch pipes 42, by adopting this structure, the blowing main pipe 41 It can be communicated with an external air supply device, such as an air compressor or a fan, and the air supply device can keep supplying air to the air blowing main pipe 41, so that the air can enter the air blowing channel through the air blowing branch pipe 42 37, and blow out from the blowing channel 37, and blow into the lumen 54 of the double-layer plastic pipe 5, so that the inner wall of the outer pipe 51 and the inner pipe 52 can be well avoided. The outer walls are bonded to effectively ensure the yield of the double-layer plastic pipe 5 . In addition, preferably, the main air blowing pipe 41 is annular.

Specifically, the blowing channel 37 passes through the outer mold body 31 and the outer ring 332 , the connecting block 333 , and the inner ring 331 of the hollow mold body 33 in sequence.

As shown in FIGS. 2 and 5 , specifically, the vacuum setting and cooling mechanism 2 includes a support frame 21 , an outer setting sleeve 22 , an inner setting sleeve 23 , a vacuum setting assembly 24 and a circulating cooling assembly 25 . The outer setting sleeve 25 . 22 is fixedly installed on the support frame 21 and used to be sleeved on the outer side of the outer tube 51, and the inner shaping sleeve 23 is connected with the double-layer extrusion molding die 3 and used to be sleeved on the inner side of the inner tube 52, The vacuum sizing assembly 24 and the circulating cooling assembly 25 are arranged in sequence along the conveying direction of the double-layer plastic pipe 5 , the outer sizing sleeve 22 is provided with a number of outer adsorption holes 221 , and the inner sizing sleeve 23 has a surface A plurality of inner adsorption holes 231 are provided, and the vacuum forming component 24 communicates with the outer adsorption holes 221 and the inner adsorption holes 231 and plays a role in vacuum forming the outer tube 51 and the inner tube 52 . The circulating cooling assembly 25 is used for circulating cooling the outer sizing sleeve 22 and the inner sizing sleeve 23 .

As shown in FIG. 2 and FIG. 5 , specifically, the vacuum sizing assembly 24 includes a vacuum pump 241 , an outer vacuum annular cover 242 and an inner vacuum annular cover 243 , the vacuum pump 241 is fixedly installed on the support frame 21 , and the The outer vacuum annular cover 242 is fixedly sleeved on the outer side of the outer shaping sleeve 22 and covers a plurality of the outer suction holes 221 , and the inner vacuum annular cover 243 is fixedly sleeved on the inner side of the inner shaping sleeve 23 and covers a number of the inner suction holes 221 . Adsorption hole 231, the vacuum pump 241 communicates with the outer vacuum annular cover 242 through an outer vacuum pipe 244, the vacuum pump 241 communicates with the inner vacuum annular cover 243 through an inner vacuum pipe 245, and the double-layer extrusion molding die 3 is also provided with a first connection channel 38 through which the inner vacuum tube 245 can pass. By adopting this structure, the vacuum pump 241 can pump the outer vacuum annular cover 242 and the inner vacuum annular cover 243 vacuum, and through the outer adsorption hole 221 and the inner adsorption hole 231 respectively, the outer tube 51 and the inner tube 52 have a good vacuum adsorption effect, and make the outer wall of the outer tube 51 and the The inner wall of the outer sizing sleeve 22 abuts and fits, and the inner wall of the inner tube 52 abuts and fits the inner wall of the inner sizing sleeve 23, and the outer sizing sleeve 22 and the inner sizing sleeve 23 play corresponding constraints. Therefore, the outer tube 51 and the inner tube 52 can have a good vacuum setting effect respectively.

As shown in FIG. 2 , specifically, the circulating cooling assembly 25 includes a water pump 251 , a water tank 252 , cooling fins 253 , an outer cooling annular cover 254 and an inner cooling annular cover 255 . The cooling fins 253 are all fixedly mounted on the support frame 21 , the outer cooling annular cover 254 is fixedly sleeved on the outer side of the outer shaping sleeve 22 , and the inner cooling annular cover 255 is fixedly sleeved on the inner shaping Inside the sleeve 23, the water inlet end of the water pump 251 is communicated with the water tank 252, the water outlet end of the water pump 251 is communicated with the outer cooling annular cover 254 through the outer water inlet pipe 2561, and is connected with the outer cooling ring 254 through the inner water inlet pipe 2562. The inner cooling annular cover 255 is communicated with, the outer cooling annular cover 254 is communicated with the cooling fins 253 through an outer water outlet pipe 2571, and the inner cooling annular cover 255 is connected with the cooling fins 253 through an inner water outlet pipe 2572. The cooling fins 253 communicate with the water tank 252, and the double-layer extrusion molding die 3 is also provided with two inner water inlet pipes 2562 and the inner water outlet pipes 2572 respectively passing through them. With the second connection channel 39, by adopting this structure, the water pump 251 can supply the water in the water tank 252 to the outer cooling annular cover 254 and the outer cooling ring 254 through the outer water inlet pipe 2561 and the inner water inlet pipe 2562, respectively. In the inner cooling annular cover 255, after the water flow circles the outer cooling annular cover 254 and the inner cooling annular cover 255, it can effectively cool the outer sizing sleeve 22 and the inner sizing sleeve 23. Therefore, the outer tube 51 and the inner tube 52 have a good cooling effect. Then, the water in the outer cooling annular cover 254 and the inner cooling annular cover 255 can pass through the The outer water outlet pipe 2571 and the inner water outlet pipe 2572 flow into the heat dissipation fins 253 for cooling, and the cooled water will return to the water tank 252 again, thereby effectively recycling the water.

Specifically, both the first connection channel 38 and the second connection channel 39 pass through the core mold body 32 .

As shown in FIG. 2 , in addition, the circulating cooling assembly 25 further includes a filter box 258 , and the water inlet end of the water pump 251 communicates with the water tank 252 through the filter box 258 . Specifically, the filter box 258 There is a filter screen inside, and one side of the filter screen is provided with filter cotton, which can play the role of filtering impurities, so as to ensure the cleanness of the circulating water and avoid clogging.

The molding process of the double-layer plastic pipe extrusion molding production line adopts any one of the above-mentioned double-layer plastic pipe extrusion molding production line for molding, including the following steps:

Step 1: Extrusion molding, the extruder 1 extrudes the double-layer plastic tube 5 with the outer tube 51, the inner tube 52 and several reinforcing ribs 53 through the double-layer extrusion molding die 3, that is, when the extruder 1 passes the raw material through When the double-layer extrusion molding die 3 is extruded, the first extrusion flow channel 34 is used to form the outer tube 51 of the double-layer plastic tube 5 , and the second extrusion flow channel 35 is used to form the inner tube 52 of the double-layer plastic tube 5 . , the gap 3311 is used to form the reinforcing rib 53 of the double-layer plastic pipe 5;

Step 2: Blow air to prevent sticking. During the extrusion molding process of the double-layer plastic tube 5, air is blown through the cavity 54 formed by the outer tube 51, the inner tube 52 and the reinforcing ribs 53 to avoid the outer tube 51. The inner wall is bonded to the outer wall of the inner pipe 52, that is, the air supply device keeps supplying air to the main air blowing pipe 41, so that the gas enters the air blowing channel 37 through the air blowing branch pipe 42, and is blown into the lumen from the air blowing channel 37. within 54.

Step 3: Vacuum shaping, by vacuum shaping and adsorbing the formed outer tube 51 and the inner tube 52 at the same time, that is, vacuuming the outer vacuum annular cover 242 and the inner vacuum annular cover 243 by the vacuum pump 241, and passing through the outer adsorption holes respectively 221 and the inner adsorption hole 231 have a good vacuum adsorption effect on the outer tube 51 and the inner tube 52, and make the outer wall of the outer tube 51 and the inner wall of the outer shaping sleeve 22 abut and fit, and make the inner wall of the inner tube 52 and the inner shaping sleeve 23 The inner walls are abutted against each other, and the outer sizing sleeve 22 and the inner sizing sleeve 23 play a corresponding restraining role, so that the outer tube 51 and the inner tube 52 can respectively play a good role in vacuum shaping;

Step 4: Circulating cooling, through the simultaneous cooling and cooling of the outer tube 51 and the inner tube 52 after being shaped, that is, the water in the water tank 252 is supplied to the outer cooling ring through the outer water inlet pipe 2561 and the inner water inlet pipe 2562 through the water pump 251 respectively. In the cover 254 and the inner cooling annular cover 255, after the water flow circles the outer cooling annular cover 254 and the inner cooling annular cover 255, the outer sizing sleeve 22 and the inner sizing sleeve 23 can be effectively cooled, and thus the outer tube can be cooled. 51 and the inner pipe 52 have a good cooling effect, and then, the water in the outer cooling annular cover 254 and the inner cooling annular cover 255 can flow to the cooling fins 253 through the outer water outlet pipe 2571 and the inner water outlet pipe 2572 respectively for cooling. The cooled water will be returned to the water tank 252 again, thereby effectively recycling the water.

The above are only some specific embodiments of the present invention, but the design concept of the present invention is not limited to this, and any non-substantial modification of the present invention by using this concept shall be an act that infringes the protection scope of the present invention.

Claims (10)

1. Double-deck plastic tubing extrusion moulding production line, its characterized in that: including extruder, vacuum design and the cooling body that sets gradually, the end fixed mounting that extrudes of extruder has double-deck extrusion moulding mould, double-deck extrusion moulding mould is used for the shaping to have the double-deck plastic tubing of outer tube, inner tube and a plurality of strengthening rib, the outer tube inner tube and adjacent two be formed with the lumen between the strengthening rib, be connected with on the double-deck extrusion moulding mould and be used for toward blow in the lumen in order to avoid the outer tube inner wall with the mechanism of blowing that the inner tube outer wall bonded mutually, vacuum design and cooling body are used for behind the shaping the outer tube reaches the inner tube plays vacuum design and cooling effect simultaneously.

2. The double-layer plastic pipe extrusion molding production line according to claim 1, characterized in that: be equipped with in the double-deck extrusion moulding mould and be used for the shaping the first runner of extruding of outer tube, be used for the shaping the runner and be used for the shaping are extruded to the second of inner tube a plurality of breachs of strengthening rib, the first runner of extruding passes through the breach with the runner is extruded to the second communicates with each other.

3. The double-layer plastic pipe extrusion molding production line according to claim 2, characterized in that: the double-layer extrusion molding die comprises an outer die body, a core die body and a hollow die body, wherein the outer die body is fixedly connected with an extruder and sleeved on the core die body, the hollow die body comprises an inner ring and an outer ring which are sequentially arranged inside and outside, the inner ring is fixedly connected with the outer ring into a whole through a plurality of connecting blocks, the outer ring is connected onto the outer die body and enables one end of the core die body to penetrate through the inner ring, the outer ring is formed between the inner ring and a first extrusion flow channel, the inner ring is formed between the core die body and a second extrusion flow channel, and the gaps are uniformly arranged in the circumferential direction of the inner ring and are arranged on the inner ring.

4. The double-layer plastic pipe extrusion molding production line according to claim 3, characterized in that: an extrusion molding runner is further formed between the outer die body and the core die body, and the first extrusion runner and the second extrusion runner are communicated with each other.

5. The double-layer plastic pipe extrusion molding production line according to claim 1, characterized in that: the blowing mechanism comprises a blowing main pipeline used for conveying gas, a plurality of blowing channels which can be in one-to-one correspondence with the pipe cavities are arranged on the double-layer extrusion forming die, and the blowing main pipeline is communicated with the blowing channels one by one through a plurality of blowing branch pipelines.

6. The double-layer plastic pipe extrusion molding production line according to claim 1, characterized in that: the vacuum shaping and cooling mechanism comprises a support frame, an outer shaping sleeve, an inner shaping sleeve, a vacuum shaping assembly and a circulating cooling assembly, the outer shaping sleeve is fixedly installed on the support frame and is sleeved outside the outer pipe, the inner shaping sleeve is connected with the double-layer extrusion molding die and is sleeved inside the inner pipe, the vacuum shaping assembly and the circulating cooling assembly are sequentially arranged along the conveying direction of the double-layer plastic pipe, a plurality of outer adsorption holes are formed in the surface of the outer shaping sleeve, a plurality of inner adsorption holes are formed in the surface of the inner shaping sleeve, the vacuum shaping assembly is communicated with the outer adsorption holes and the inner adsorption holes and plays a role in vacuum shaping on the outer pipe and the inner pipe, and the circulating cooling assembly is used for playing a role in circulating cooling on the outer shaping sleeve and the inner shaping sleeve.

7. The double-layer plastic pipe extrusion molding production line according to claim 6, characterized in that: the vacuum shaping assembly comprises a vacuum pump, an outer vacuum annular cover and an inner vacuum annular cover, the vacuum pump is fixedly installed on the support frame, the outer vacuum annular cover is fixedly sleeved on the outer shaping cover and covers a plurality of outer adsorption holes, the inner vacuum annular cover is fixedly sleeved on the inner shaping cover and covers a plurality of inner adsorption holes, the vacuum pump is communicated with the outer vacuum annular cover through an outer vacuum tube, the vacuum pump is communicated with the inner vacuum annular cover through an inner vacuum tube, and a first connecting channel capable of enabling the inner vacuum tube to penetrate is further arranged on the double-layer extrusion molding die.

8. The double-layer plastic pipe extrusion molding production line according to claim 6, characterized in that: the circulating cooling assembly comprises a water pump, a water tank, radiating fins, an outer cooling annular cover and an inner cooling annular cover, the water pump, the water tank and the radiating fins are all fixedly arranged on the supporting frame, the outer cooling annular cover is fixedly sleeved outside the outer sizing sleeve, the inner cooling annular cover is fixedly sleeved on the inner side of the inner shaping sleeve, the water inlet end of the water pump is communicated with the water tank, the water outlet end of the water pump is communicated with the outer cooling annular cover through an outer water inlet pipe and is communicated with the inner cooling annular cover through an inner water inlet pipe, the outer cooling annular cover is communicated with the radiating fins through an outer water outlet pipe, the inner cooling annular cover is communicated with the radiating fins through an inner water outlet pipe, the double-layer extrusion molding die is also provided with two second connecting channels which can enable the inner water inlet pipe and the inner water outlet pipe to respectively penetrate through.

9. The double-layer plastic pipe extrusion molding production line according to claim 8, characterized in that: the circulating cooling assembly further comprises a filter box, and the water inlet end of the water pump is communicated with the water tank through the filter box.

10. The forming process of the double-layer plastic pipe extrusion forming production line is characterized in that: the double-layer plastic pipe extrusion molding production line of any one of claims 1 to 9 is used for molding, and comprises the following steps:

step 1: extruding and molding, wherein an extruder extrudes a double-layer plastic pipe with an outer pipe, an inner pipe and a plurality of reinforcing ribs through a double-layer extrusion molding die;

step 2: the blowing anti-sticking device is characterized in that blowing is carried out on a pipe cavity formed by encircling the outer pipe, the inner pipe and the reinforcing ribs in the extrusion molding process of the double-layer plastic pipe so as to prevent the inner wall of the outer pipe from being bonded with the outer wall of the inner pipe;

and step 3: vacuum shaping, namely simultaneously carrying out vacuum shaping adsorption on the shaped outer pipe and the shaped inner pipe;

and 4, step 4: and (4) cooling circularly, namely cooling circularly by simultaneously cooling the shaped outer pipe and the shaped inner pipe.

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