Horizontal infrared crosslinking furnace

Abstract

The invention discloses a horizontal infrared cross-linking furnace, and relates to the technical field of plastic processing, the horizontal infrared cross-linking furnace comprises a cross-linking box, a bottom box, an anti-sticking pipe supporting roller and an air supply mechanism, the cross-linking box is arranged at the top of the bottom box, and a cross-linking cavity extending horizontally is arranged in the cross-linking box; a cross-linking furnace infrared heating tube used for heating the PE-Xa hot melting tube blank in the cross-linking cavity is further arranged in the cross-linking box, the anti-sticking tube supporting roller is used for supporting the PE-Xa hot melting tube blank and is supported in the cross-linking cavity through a tube supporting roller support, and the gas supply mechanism is used for conveying inert gas into the cross-linking cavity; the horizontal infrared crosslinking furnace disclosed by the invention has the advantages of being wide in pipe specification, high in crosslinking efficiency, low in fire risk, energy-saving, environment-friendly and easy to operate.

Description

Technical Field

[0001] The invention relates to the technical field of plastic processing, in particular to a horizontal infrared cross-linking furnace. Background Art

[0002] Polyethylene (PE) is one of the five general-purpose plastics. Its output and consumption rank first among all kinds of synthetic resins. It is widely used in industry, agriculture and daily life. However, polyethylene has poor high temperature resistance. Mechanical properties and chemical resistance sometimes cannot meet the requirements of actual use. Therefore, modification of polyethylene has always been the key to the development and application of polyethylene products. Polyethylene cross-linking technology is an important technology to improve its material properties. Cross-linked polyethylene can greatly improve its performance, not only significantly improving the mechanical properties, environmental stress cracking resistance, chemical corrosion resistance, creep resistance and electrical properties of polyethylene, but also significantly improving the temperature resistance level. For example, ordinary PE pipes cannot transport media with a temperature exceeding 45°C. After cross-linking modification, the temperature can be raised to 70°C, which greatly broadens the application range of polyethylene.

[0003] PE-Xa pipe has good temperature resistance and creep resistance. It is mainly used for radiant heating, radiant cooling, domestic hot and cold water, and radiator connection pipes. It is one of the most stable series of polyethylene products and has broad application prospects. The traditional production process of PE-Xa pipe is synchronous cross-linking by plunger machine. This process has simple equipment, small one-time investment, simple operation, and adaptability to a wide range of pipe specifications. However, its disadvantages are low efficiency, high noise, pulsed changes in the bulk density of the pipe wall, uneven pipe performance, and easy bamboo-like appearance. Currently, the commercialized screw extrusion post-cross-linking PE-Xa pipe uses a vertical infrared cross-linking furnace. The vertical infrared post-cross-linking process of PE-Xa pipe has high production efficiency, uniform bulk density of the pipe wall, and stable performance, but it has the disadvantages of a narrow range of pipe specifications, low cross-linking efficiency, easy ignition, high energy consumption, and difficult operation. Summary of the invention

[0004] The purpose of the present invention is to provide a horizontal infrared cross-linking furnace to solve the problems existing in the above-mentioned prior art, which has the advantages of adapting to a wide range of pipe specifications, high cross-linking efficiency, low fire risk, energy saving and environmental protection, and easy operation.

[0005] To achieve the above object, the present invention provides the following solutions:

[0006] The present invention provides a horizontal infrared cross-linking furnace, comprising a cross-linking box, a bottom box, an anti-sticking tube roller and an air supply mechanism, wherein the cross-linking box is arranged on the top of the bottom box, a horizontally extending cross-linking cavity is arranged inside the cross-linking box, and a cross-linking furnace infrared heating tube for heating a PE-Xa hot-melt pipe embryo in the cross-linking cavity is also arranged inside the cross-linking box, the anti-sticking tube roller is used to support the PE-Xa hot-melt pipe embryo and is supported in the cross-linking cavity by a tube roller bracket, and the air supply mechanism is used to transport an inert gas into the cross-linking cavity.

[0007] Preferably, both ends of the cross-linking box are respectively provided with a pipe inlet and a pipe outlet.

[0008] Preferably, the cross-linking box comprises a left box body and a right box body, the left box body and the right box body are symmetrically arranged and the opening and closing are controlled by an electric push rod arranged at the bottom.

[0009] Preferably, the infrared heating tube of the cross-linking furnace is embedded in the box wall of the cross-linking box, an electric heating wire is arranged in the infrared heating tube of the cross-linking furnace, and the infrared heating tube of the cross-linking furnace is coated with a high-temperature resistant nano coating.

[0010] Preferably, casters are provided at the bottom of the bottom box, the casters are matched with the track between the extruder and the sizing cooling device of the post-cross-linked PE-Xa pipe production line, and the casters are driven by a driving mechanism.

[0011] Preferably, the bottom end of the managed roller bracket is located in the bottom box, and a managed roller lifting push rod for controlling the height of the anti-sticking managed roller is provided at the bottom end of the managed roller bracket.

[0012] Preferably, there are at least two anti-sticking tube rollers distributed along the length direction of the cross-linking chamber.

[0013] Preferably, the gas supply mechanism is a nitrogen generator, the gas outlet of the nitrogen generator is connected to a nitrogen main pipe, and the nitrogen main pipe is provided with a plurality of nitrogen branch pipes connected to the cross-linking cavity.

[0014] Preferably, both ends of the bottom box are provided with cross-linking furnace center height adjustment bolts.

[0015] Preferably, the anti-sticking trustee roller is made of stainless steel, and the outside of the anti-sticking trustee roller is sprayed with a high-temperature resistant anti-stick coating.

[0016] Compared with the prior art, the present invention has achieved the following technical effects:

[0017] 1. Adapt to a wide range of pipe specifications: Compared with the vertical infrared cross-linking furnace, the horizontal infrared cross-linking furnace can adapt to the manufacture of most or even all specifications of pipes.

[0018] 2. High cross-linking efficiency: The furnace chamber is filled with nitrogen, which can effectively reduce the loss of cross-linking agent during the cross-linking process of PE-Xa tubes, improve the cross-linking efficiency, and reduce the risk of thermal oxidation degradation on the surface of PE-Xa tube embryos.

[0019] 3. Low fire risk: The oxygen index of PE is 17%. In the post-crosslinking atmosphere of the PE-Xa pipe of the present invention, the oxygen concentration is controlled below 15%, thereby reducing the fire risk during the crosslinking process of the post-crosslinked PE-Xa pipe.

[0020] 4. Energy saving and environmental protection: The inner material of the infrared heating tube of the cross-linking furnace is electric heating wire, and the outer surface is coated with high-temperature resistant nano-coating, which improves the heating efficiency and saves energy.

[0021] 5. Prevent pipe collapse: The furnace is equipped with a trustee roller, the height of which is adjustable and the surface is sprayed with a high-temperature resistant anti-stick coating to prevent the pipe from collapsing.

[0022] 6. Easy to operate: When guiding the pipe, since the cross-linking furnace is placed horizontally, the operator does not need to climb to complete the pipe guiding.

[0023] 7. Good surface condition of the pipe: The surface of the tube roller is sprayed with a high-temperature resistant anti-stick coating, which effectively reduces the problem of adhesion of the pipe embryo and makes the surface of the prepared pipe uniform and complete. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0025] Figure 1 It is a front view of the horizontal infrared cross-linking furnace in the present invention;

[0026] Figure 2 It is a side view of the horizontal infrared cross-linking furnace of the present invention;

[0027] In the figure: 1. pipe inlet; 2. junction box; 3. casters; 4. nitrogen branch pipe; 5. nitrogen generator; 6. nitrogen main pipe; 7. track; 8. tube roller bracket; 9. tube roller lifting push rod; 10. electric push rod; 11. pipe outlet; 12. driving mechanism; 13. cross-linking furnace center height adjustment bolt; 14. cross-linking furnace infrared heating tube; 15. anti-sticking tube roller; 16. cross-linking box; 17. furnace cavity; 18. bottom box. DETAILED DESCRIPTION

[0028] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0029] The purpose of the present invention is to provide a horizontal infrared cross-linking furnace to solve the problems existing in the prior art.

[0030] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the present invention is further described in detail below with reference to the accompanying drawings and specific embodiments.

[0031] The horizontal infrared cross-linking furnace in this embodiment is as follows Figure 1-Figure 2 As shown, it includes a cross-linking box 16, a bottom box 18, an anti-sticking tube roller 15 and an air supply mechanism. The cross-linking box 16 is arranged on the top of the bottom box 18. A horizontally extending cross-linking cavity is arranged inside the cross-linking box 16. The cross-linking box 16 is also provided with a cross-linking furnace infrared heating tube 14 for heating the PE-Xa hot melt tube embryo in the cross-linking cavity. The anti-sticking tube roller 15 is used to support the PE-Xa hot melt tube embryo and is supported in the cross-linking cavity by the tube roller bracket 8. The air supply mechanism is used to transport inert gas into the cross-linking cavity.

[0032] In this specific embodiment, a pipe inlet 1 and a pipe outlet 11 are respectively provided at both ends of the cross-linking box 16 . The PE-Xa hot melt pipe blank enters the cross-linking chamber from the pipe inlet 1 and leaves the cross-linking chamber from the pipe outlet 11 .

[0033] In this specific embodiment, the cross-linking box 16 includes a left box body and a right box body, which are symmetrically arranged and are controlled to open and close by an electric push rod 10 arranged at the bottom.

[0034] In this specific embodiment, the cross-linking furnace infrared heating tube 14 is embedded in the box wall of the cross-linking box 16, an electric heating wire is arranged in the cross-linking furnace infrared heating tube 14, and the cross-linking furnace infrared heating tube 14 is coated with a high temperature resistant nano coating.

[0035] In this specific embodiment, casters 3 are provided at the bottom of the bottom box 18, and the casters 3 are cooperated with the track 7 between the extruder and the sizing cooling device of the post-cross-linked PE-Xa pipe production line. The casters 3 are driven by the driving mechanism 12, and the movement of the entire cross-linking furnace is controlled by the casters 3 and the driving mechanism 12 (which can be a motor gear driving mechanism 12).

[0036] In this specific embodiment, the bottom end of the managed roller bracket 8 is located in the bottom box 18, and the bottom end of the managed roller bracket 8 is provided with a managed roller lifting push rod 9 for controlling the height of the anti-sticking managed roller 15. The managed roller lifting push rod 9 can be an electric push rod 10 or a pneumatic push rod, etc., which controls the height of the anti-sticking managed roller 15 to adapt to PE-Xa pipes of different specifications.

[0037] In this specific embodiment, there are at least two anti-sticking tube rollers 15 distributed along the length direction of the cross-linking chamber, and the spacing between the anti-sticking tube rollers 15 should ensure that the tube embryo does not leave the radiation heating hot spot of the horizontal cross-linking furnace after sagging.

[0038] In this specific embodiment, the gas supply mechanism is a nitrogen generator 5, the gas outlet of the nitrogen generator 5 is connected to the nitrogen main pipe 6, and a plurality of nitrogen branch pipes 4 connected to the cross-linking chamber are arranged on the nitrogen main pipe 6. In order to improve the cross-linking efficiency and reduce the oxidative degradation of the cross-linked polyethylene product by oxygen in the hot air, and prevent the occurrence of fire, the nitrogen generator 5 is transported to the furnace chamber 17 through the nitrogen main pipe 6 and then through the nitrogen branch pipes 4, so that the oxygen concentration in the furnace chamber 17 is reduced to below 15%.

[0039] In this specific embodiment, the two ends of the bottom box 18 are provided with cross-linking furnace center height adjustment bolts 13, and the cross-linking furnace is supported by the cross-linking furnace center height adjustment bolts 13 to adjust the height of the cross-linking furnace from the ground so that the center of the cross-linking cavity is consistent with the center of the extruder die.

[0040] In this specific embodiment, the anti-sticking trustee roller 15 is made of stainless steel, and the anti-sticking trustee roller 15 is sprayed with a high-temperature resistant anti-stick coating.

[0041] In this specific embodiment, a plurality of junction boxes 2 are disposed outside the cross-linking box 16 .

[0042] The horizontal infrared cross-linking furnace in this embodiment is height-adjustable, and an anti-sticking tube roller is provided in the furnace, the height of the anti-sticking tube roller is adjustable, and the surface is sprayed with a high-temperature resistant anti-stick coating; the cross-linked polyethylene pipe is transported horizontally in the furnace cavity through the anti-sticking tube roller; infrared heating tubes are provided on the four walls of the furnace, and the furnace temperature is adjustable to 500°C. The heat required for the cross-linking process of the polyethylene pipe is supplied by the infrared heating tube in the form of radiation heat and convection heat; in order to improve the cross-linking efficiency and reduce the oxidative degradation of the cross-linked polyethylene products by oxygen in the hot air, and to prevent the occurrence of fire, the nitrogen generator is transported to the furnace cavity through the nitrogen main pipe and then through the nitrogen branch pipe, so that the oxygen concentration in the furnace cavity is reduced to below 15%. When the production speed of the polyethylene pipe that needs to be cross-linked is slow, only one horizontal infrared cross-linking furnace can be used; when the production speed of the polyethylene pipe that needs to be cross-linked is high, multiple horizontal infrared cross-linking furnaces can be used in series to form an infrared cross-linking unit.

[0043] The specific operation process is as follows:

[0044] Place the infrared cross-linking furnace on the track 7 between the extruder and the sizing cooling device of the post-cross-linking PE-Xa pipe production line, adjust the center height adjustment bolt 13 of the cross-linking furnace to make the center of the cross-linking cavity consistent with the center of the extruder die, adjust the tube roller lifting push rod 9 according to the specifications of the manufactured PE-Xa pipe to make the height of the tube roller appropriate, install the guide rope, move the cross-linking furnace to keep a convenient operating distance between the cross-linking furnace entrance and the extruder die, close the cross-linking furnace, connect and start the power of the infrared cross-linking furnace, set the required startup temperature, start the nitrogen generator 5, start the extruder, connect the pipe blank spitted out from the die to the guide rope, start the traction machine, and adjust the cross-linking furnace temperature, extrusion rate of the extruder, traction rate of the traction machine and the distance between the extruder die and the cross-linking furnace entrance according to the production requirements of PE-Xa pipes.

[0045] The PE-Xa tube embryo that has completed the cross-linking process is introduced into a vacuum sizing cooling water tank for sizing and cooling, just like the manufacturing process of ordinary thermoplastic plastic pipes, and then pulled, cut, collected, etc.

[0046] The following are examples and comparative examples:

[0047] Embodiment 1:

[0048] The horizontal infrared cross-linking furnace was set at 260℃, the oxygen content in the air was 15%, and an anti-sticking tube roller 15 was installed to cross-link the DN16 PE-Xa pipe. The cross-linking degree of the obtained PE-Xa pipe was 80%, the oxidation induction period at 200℃ was 50min, the surface of the pipe was smooth without burrs, and the ovality was small.

[0049] Embodiment 2:

[0050] The horizontal infrared cross-linking furnace was set at 260°C, the oxygen content in the air was 13%, and an anti-sticking tube roller 15 was installed to cross-link the DN16 PE-Xa pipe. The cross-linking degree of the obtained PE-Xa pipe was 83.2%, the oxidation induction period at 200°C was 48 minutes, the surface of the pipe was smooth without burrs, and the ovality was small.

[0051] Embodiment 3:

[0052] The horizontal infrared cross-linking furnace was set at 280℃, the oxygen content in the air was 15%, and an anti-sticking tube roller was installed to cross-link the DN16 PE-Xa pipe. The cross-linking degree of the obtained PE-Xa pipe was 81.2%, the oxidation induction period at 200℃ was 45min, the surface of the pipe was smooth without burrs, and the ovality was small.

[0053] Comparative Example 1:

[0054] The horizontal infrared cross-linking furnace was set at 260°C, the oxygen content in the air was 23%, and an anti-sticking tube roller 15 was installed to cross-link the DN16 PE-Xa pipe. The cross-linking degree of the obtained PE-Xa pipe was 72%, the oxidation induction period at 200°C was 40 minutes, the surface of the pipe was smooth without burrs, and the ovality was small.

[0055] Comparative Example 2:

[0056] In the horizontal infrared cross-linking furnace, the temperature was set at 260℃, the oxygen content in the air was 23%, and the anti-sticking tube roller 15 was not installed. The DN16 PE-Xa tube was cross-linked. The tube embryo sagged seriously and was easy to break, which made the experiment unable to continue.

[0057] The present invention uses specific examples to illustrate the principles and implementation methods of the present invention. The above examples are only used to help understand the method and core ideas of the present invention. At the same time, for those skilled in the art, according to the ideas of the present invention, there will be changes in the specific implementation methods and application scope. In summary, the content of this specification should not be understood as limiting the present invention.

Claims

1. A horizontal infrared cross-linking furnace, characterized in that: It includes a cross-linking box, a bottom box, an anti-sticking tube roller and an air supply mechanism. The cross-linking box is arranged on the top of the bottom box. A horizontally extending cross-linking cavity is arranged inside the cross-linking box. The cross-linking box is also provided with a cross-linking furnace infrared heating tube for heating the PE-Xa hot-melt pipe embryo in the cross-linking cavity. The anti-sticking tube roller is used to support the PE-Xa hot-melt pipe embryo and is supported in the cross-linking cavity by the tube roller bracket. The air supply mechanism is used to transport inert gas into the cross-linking cavity.

2. The horizontal infrared cross-linking furnace according to claim 1, characterized in that: The two ends of the cross-linking box are respectively provided with a pipe inlet and a pipe outlet.

3. The horizontal infrared cross-linking furnace according to claim 1, characterized in that: The cross-linking box comprises a left box body and a right box body, the left box body and the right box body are symmetrically arranged and the opening and closing are controlled by an electric push rod arranged at the bottom.

4. The horizontal infrared cross-linking furnace according to claim 1, characterized in that: The infrared heating tube of the cross-linking furnace is embedded in the box wall of the cross-linking box, an electric heating wire is arranged in the infrared heating tube of the cross-linking furnace, and the infrared heating tube of the cross-linking furnace is plated with a high-temperature resistant nano coating.

5. The horizontal infrared cross-linking furnace according to claim 1, characterized in that: The bottom of the bottom box is provided with casters, the casters are matched with the track between the extruder and the sizing cooling device of the post-crosslinking PE-Xa pipe production line, and the casters are driven by a driving mechanism to move.

6. The horizontal infrared cross-linking furnace according to claim 1, characterized in that: The bottom end of the managed roller bracket is located in the bottom box, and the bottom end of the managed roller bracket is provided with a managed roller lifting push rod for controlling the height of the anti-sticking managed roller.

7. The horizontal infrared cross-linking furnace according to claim 1, characterized in that: At least two anti-sticking tube rollers are distributed along the length direction of the cross-linking chamber.

8. The horizontal infrared cross-linking furnace according to claim 1, characterized in that: The gas supply mechanism is a nitrogen generator, the gas outlet of the nitrogen generator is connected to the nitrogen main pipe, and the nitrogen main pipe is provided with a plurality of nitrogen branch pipes connected to the cross-linking cavity.

9. The horizontal infrared cross-linking furnace according to claim 1, characterized in that: Both ends of the bottom box are provided with cross-linking furnace center height adjustment bolts.

10. The horizontal infrared cross-linking furnace according to claim 1, characterized in that: The anti-sticking trustee roller is made of stainless steel, and a high-temperature resistant anti-stick coating is sprayed on the outside of the anti-sticking trustee roller.

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