TW202413054A - Extrusion molding equipment, extrusion molding system and mold for coating metal pipes with polyvinyl chloride dipping liquid - Google Patents

Abstract

An extrusion molding device, an extrusion molding system and a mold thereof for coating a polyvinyl chloride dipping liquid on a metal pipe. The extrusion molding device comprises a primer device and an extrusion molding system. The primer device is used to coat a primer layer on the metal pipe. The extrusion molding system comprises a feeding device, a preheating device, a mold and a sol supply device. The mold is used to extrude the polyvinyl chloride dipping liquid to coat the primer layer to form a plastic layer. The mold has a tube channel, two fluid channels and a glue channel. The glue channel is used to extrude the polyvinyl chloride dipping liquid to coat the primer layer of the metal pipe. The sol supply device has at least one glue storage cylinder for loading the polyvinyl chloride dipping solution and a driving unit. The driving unit is used to inject the polyvinyl chloride dipping solution into the glue channel of the mold.

Description

Extrusion molding equipment for coating polyvinyl chloride dipping liquid on metal pipe, extrusion molding system and mold thereof

The present invention relates to an extrusion molding device for plastics, in particular to an extrusion molding device for coating a metal pipe with polyvinyl chloride dipping liquid, an extrusion molding system and a mold thereof.

Polyvinyl chloride (PVC) coated pipes have excellent insulation and corrosion resistance, which can extend the service life of electrical pipeline systems in harsh environments. They are often used in wire transmission pipes, petrochemical industry piping, and power communication protection pipes.

The common method for manufacturing PVC coated pipes is the dipping method, which involves completely submerging the preheated metal pipe into a large dipping tank containing a PVC solution for dipping and adhesion. After exiting the tank, the pipe is shaped and dried to form a PVC protective layer on the outer surface of the metal pipe. However, the metal pipe often has a vertical flow problem after exiting the tank, which affects the quality. In addition, the film thickness and roundness of the PVC protective layer produced by this method are relatively uneven, and the quality is inconsistent. In addition, during the operation, a large area of the preheated metal pipe is exposed to the PVC solution, which generates a large amount of operating waste gas, which is not environmentally friendly and needs to be improved.

Therefore, the first object of the present invention is to provide an extrusion molding device for coating a metal tube with polyvinyl chloride dipping liquid, which has stable film thickness and quality and is more environmentally friendly.

Therefore, the present invention is an extrusion molding device for coating a metal tube with polyvinyl chloride dipping liquid, comprising a primer device and an extrusion molding system.

The primer device includes a painting unit, which is used to apply a primer layer on the outer peripheral surface of the metal pipe.

The extrusion molding system is used to extrude the polyvinyl chloride dipping liquid to coat the primer layer of the metal pipe to form a plastic layer. The extrusion molding system is arranged along a feeding path and includes a feeding device, a preheating device, a mold and a sol supply device. The feeding device is used to drive the metal pipe to move and generate a thrust force for the metal pipe to move along the feeding path, so that the metal pipe with the primer layer can move forward along the feeding path. The preheating device is located on the feeding path and is used to heat the metal pipe with the primer layer.

The mold is located on the feeding path and adjacent to the preheating device. The mold is used to extrude the polyvinyl chloride dipping liquid to coat the primer layer of the metal pipe to form the plastic layer. The mold has a mold body and a heating module arranged on the mold body. The mold body defines a pipe channel surrounding an axis and for the metal pipe to pass through. The mold body has an inlet end adjacent to the preheating device, an outlet end opposite to the inlet end on the feeding path, two fluid channels surrounding the axis and between the inlet end and the outlet end, and a glue channel surrounding the axis and between the fluid channels. The fluid channels are used to pass fluid that blocks the heat source. The rubber channel is in communication with the tube channel space and is used to extrude and coat the polyvinyl chloride dipping liquid on the primer layer of the metal tube. The heating module is arranged at the discharge end and is used to heat the plastic layer and solidify the plastic layer. The sol supply device has at least one rubber storage cylinder for loading the polyvinyl chloride dipping liquid, and a driving unit connected to the at least one rubber storage cylinder. The driving unit is used to inject the polyvinyl chloride dipping liquid into the rubber channel of the mold.

The second purpose of the present invention is to provide a mold for a polyvinyl chloride dipping liquid extrusion molding device with stable film thickness and quality and an environmentally friendly manufacturing process.

Therefore, the mold of the polyvinyl chloride dipping liquid extrusion molding equipment of the present invention is suitable for extruding and coating the polyvinyl chloride dipping liquid on a metal tube. The mold of the polyvinyl chloride dipping liquid extrusion molding equipment includes a mold body and a heating module.

The mold body defines a tube channel surrounding an axis and allowing the metal tube to pass through along a feeding path. The mold body has an inlet end, an outlet end opposite to the inlet end, two fluid channels surrounding the axis and between the inlet end and the outlet end, and a rubber channel surrounding the axis and between the fluid channels. The fluid channels are used to pass fluid that blocks the heat source. The rubber channel is connected to the tube channel space and is used to extrude the polyvinyl chloride dipping liquid to coat the metal tube to form the plastic layer. The heating module is arranged at the outlet end of the mold body and is used to heat the plastic layer and solidify the plastic layer.

The third object of the present invention is to provide a polyvinyl chloride dipping liquid extrusion molding system with stable film thickness and quality and more environmentally friendly manufacturing process.

Therefore, the polyvinyl chloride dipping liquid extrusion molding system of the present invention is suitable for extruding and coating the polyvinyl chloride dipping liquid on a metal tube. The polyvinyl chloride dipping liquid extrusion molding system includes a feeding device, a preheating device, a mold and a sol supply device.

The feeding device is used to drive the metal tube to move and generate a pushing force for the metal tube to move along a feeding path, so that the metal tube can move along the feeding path. The preheating device is located on the feeding path and is used to heat the metal tube. The mold is located on the feeding path and adjacent to the preheating device. The mold is used to extrude the polyvinyl chloride dipping liquid to coat the metal tube to form the plastic layer. The mold has a mold body and a heating module arranged on the mold body. The mold body defines a pipe channel surrounding an axis and for the metal tube to pass through. The mold body has a feeding end adjacent to the preheating device, a heating module arranged on the feeding path opposite to the feeding end, and a heating module arranged on the feeding end. The feed end has a discharge end, two fluid channels surrounding the axis and between the feed end and the discharge end, and a rubber channel surrounding the axis and between the fluid channels, the fluid channels are used to pass fluid that blocks the heat source, the rubber channel is connected to the tube channel space and is used to extrude the polyvinyl chloride dipping liquid to coat the metal tube, the heating module is arranged at the discharge end and is used to heat the plastic layer and solidify the plastic layer. The sol supply device has at least one rubber storage cylinder for loading the polyvinyl chloride dipping liquid, and a driving unit connected to the at least one rubber storage cylinder, the driving unit is used to inject the polyvinyl chloride dipping liquid into the rubber channel of the mold.

The effect of the present invention is that: by utilizing the design of the fluid channels of the mold and cooperating with the sol supply device to stably supply glue, as the feeding device pushes the metal tube forward, the polyvinyl chloride dipping liquid can be gradually coated on the primer layer of the metal tube through the glue channel and extruded into the plastic layer. Since the present invention performs single-point coating in the mold, it can prevent the vertical flow phenomenon and save the amount of the polyvinyl chloride dipping liquid. The film thickness of the plastic layer is uniform, the roundness is good, and no operating waste gas is generated. It has the effect of stable film thickness quality and a more environmentally friendly process.

Referring to Fig. 1 to Fig. 3, the first embodiment of the extrusion equipment for coating a metal tube with a polyvinyl chloride dipping liquid is suitable for extruding a plurality of metal tubes 9 with a polyvinyl chloride dipping liquid S by an in-mold molding method to cover a plastic layer 92 and produce a PVC coated tube 90. Each of the metal tubes 9 extends along a length direction L and has an inner circumference 901 and an outer circumference 902 opposite to the inner circumference 901. The metal tube 9 of the first embodiment is a round tube, but not limited thereto. The material of the metal tube 9 is selected from iron, steel, copper, aluminum or alloy, and can be divided into four types according to the type and tube wall thickness, namely, thick wire tube, thin wire tube, EMT (Electric Metallic Tubing) and flexible metal tube. The polyvinyl chloride dipping liquid S is a commercially available product, which is a liquid made by mixing polyvinyl chloride (PVC) with various additives and undergoing multiple processes. It undergoes a crosslinking reaction and solidifies at a temperature above 160-170°C.

The extrusion equipment includes a pre-treatment device 11, a primer device 12, a pipe connection device 13, an extrusion molding system 200, a baking device 14, a cooling device 15, a discharge device 16 and a plurality of pipe transverse machines 17.

The pre-treatment device 11 is used to roughen the outer surface 902 of the metal tube 9. The pre-treatment device 11 includes a roughening unit 111 for roughening the surface, and a blower unit 112. The roughening unit 111 of the first embodiment is a sandblaster. In other embodiments, a wire wheel, a sandpaper pulley or other equivalent devices can also be used, as long as the outer surface 902 of the metal tube 9 can be roughened. Surface roughening is to increase the bonding between the metal tube 9 and the subsequent coating material. A wind cutting chamber 113 through which air flows is formed by the blower unit 112, and the air flow is sucked by a vacuum cleaner 114 to take away the dust generated when the roughening unit 111 is in operation.

The primer device 12 is located after the pretreatment device 11 and includes a painting unit 121 and an air-drying unit 122. The painting unit 121 is used to apply primer to the outer peripheral surface 902 of the roughened metal tube 9 to form a primer layer 91. The primer of the first embodiment is a commercially available liquid coating, the reaction temperature is 200°C, and the reaction time is at least 10 minutes. The provision of the primer layer 91 can increase the bonding between the metal tube 9 and the polyvinyl chloride dipping solution S.

The painting device 121 of the first embodiment has at least one brush wheel 123 containing primer, a primer cylinder 124 filled with primer liquid 120 and used to supply primer to the brush wheel 123, and a pneumatic vacuum valve 125 arranged at the bottom side of the brush wheel 123. The brush wheel 123 first absorbs the primer and then rolls the primer on the outer peripheral surface 902 of the metal tube 9 to form the primer layer 91. Specifically, the brush wheel 123 is composed of an annular paint injection seat and an annular multi-layer cloth covering the outer peripheral surface of the annular paint injection seat. The brush wheel 123 has high wear resistance. The primer cylinder 124 of the first embodiment intermittently injects paint into the brush wheel 123, so that the brush wheel 123 can continuously apply primer, and the excess primer can be discharged by the air pressure vacuum valve 125. This coating method can save the amount of primer. In other variations, the painting unit 121 can also adopt a spray paint device, a brush paint device or other equivalent devices, as long as the primer layer 91 can be formed on the outer peripheral surface 902 of the metal tube 9.

The air drying unit 122 is used to blow air to the primer layer 91 of the metal tube 9 and air dry the primer layer 91, which is convenient for the subsequent production process. The air drying unit 122 of the first embodiment has a hot air channel 126 containing circulating hot air for the metal tube 9 to pass through, a blower 127 used to form the hot air channel 126, and a heating plate 128 located on the path of the hot air channel 126 and used for heating. The air drying unit 122 can generate 50°C hot air circulation to air dry the primer layer 91 of the metal tube 9. In other variations, the air drying unit 122 can also be other air drying devices such as a vortex fan, but is not limited thereto.

Referring to FIG. 1 and FIG. 4 , the pipe connection device 13 and the primer device 12 are arranged in parallel in space and are located after the primer device 12 in the production schedule. The pipe connection device 13 is used to insert a pipe joint 8 between the two metal pipes 9 along the length direction L so that the two metal pipes 9 are connected in series along the length direction L, thereby achieving the purpose of continuous production. In other variations, the pipe connection device 13 and the primer device 12 can also be arranged in a straight line in space, as long as continuous production can be achieved.

The extrusion molding system 200 is located after the connecting device 13 and is used to extrude the polyvinyl chloride dipping liquid S to coat the primer layer 91 of the metal tube 9 to form the plastic layer 92. The extrusion molding system 200 is arranged along a feeding path P and includes a feeding device 3, a preheating device 4, a mold 5 and a sol supply device 6. The feeding path P is parallel to the length direction L of the metal tube 9.

1 , 2 and 4 , the feeding device 3 is used to drive the metal tubes 9 to move and generate a pushing force for the metal tubes 9 to move along the feeding path P, so that each of the metal tubes 9 having the primer layer 91 can move forward along the feeding path P. The feeding device 3 of the first embodiment has two conveyor belts 31 symmetrically arranged on both sides of the top and bottom of the feeding path P, and a plurality of positioning rotating member groups 32 spaced along the feeding path P. The conveyor belts 31 are belt conveyor belts, which are respectively clamped on both sides of the top and bottom of the metal tube 9 to generate the thrust force on the metal tube 9 and push the metal tube 9 forward. Since the primer layer 91 of the metal tube 9 has been dried by the air drying unit 122, the conveyor belts 31 can frictionally contact the metal tube 9. The number of the conveyor belts 31 can be determined according to the diameter of the metal tube 9. The metal tube 9 with a smaller diameter only needs two conveyor belts 31 to have sufficient pushing force, while the metal tube 9 with a larger diameter needs four conveyor belts 31, which are symmetrically arranged at the top, bottom, left and right of the feeding path P to ensure sufficient pushing force. In order to allow the metal tubes 9 to move accurately along the feeding path P, the first embodiment sets the positioning rotating member sets 32 at appropriate intervals of the feeding path P for the metal tubes 9 to slide through. Each of the positioning rotating member sets 32 has two rotating members 321 for the metal tubes 9 to slide through. In the present embodiment, each of the rotating members 321 is a ball bearing, but can also be other rotatable elements such as a roller, a pulley or a roller, and the number of the rotating members 321 can also be four in a group to be suitable for the metal tubes 9 with larger diameters.

The preheating device 4 is located on the feeding path P and is used to heat the metal tube 9 with the primer layer 91. The preheating device 4 has a plurality of heaters 41. The heaters 41 of the first embodiment are ovens and are numbered #1 to #4. The heating temperature of the heaters 41 decreases as the feeding path P advances. The metal tube 9 can reach 200°C (the reaction temperature of the primer layer 91) through multi-stage heating and completely pass through the preheating device 4 within the time (10 minutes) required for the primer layer 91 to react. In other variations, the preheating device 4 can also be replaced by a high-frequency heater and an oven. As long as the metal tube 9 can be heated to 200°C and the time for the metal tube 9 to completely pass through the preheating device 4 (the time from entering the oven No. #1 to leaving the oven No. #4) is exactly the reaction time required by the primer layer 91, the extrusion molding system 200 can maintain the same feeding speed.

The mold 5 is located on the feeding path P and adjacent to the heater 41 of the preheating device 4, which is numbered #4. The mold 5 is used to squeeze the polyvinyl chloride dipping liquid S to coat the primer layer 91 of the metal tube 9 to form the plastic layer 92. The mold 5 has a mold body 51 and a heating module 52 arranged on the mold body 51. The mold body 51 defines a tube channel 511 around an axis X and for the metal tube 9 to pass through. The mold body 51 of the first embodiment adopts a modular quick mold change design, and the required internal channel is combined by multiple modules. Therefore, the mold 5 can be replaced with a suitable one for use with the metal tube 9 of different calibers.

The mold body 51 has an inlet end 512 adjacent to the preheating device 4, an outlet end 513 opposite to the inlet end 512 on the feeding path P, two fluid channels 514 and 518 located inside and surrounding the axis X and between the inlet end 512 and the outlet end 513, a rubber channel 515 located inside and surrounding the axis X and between the fluid channels 514 and 518, and an air-cooling barrier 519. The fluid channels 514 and 518 are open to the outside and communicate with the surrounding environment space, and the fluid channels 514 and 518 are used to pass fluid that blocks the heat source. The fluid channel 514 of the first embodiment is adjacent to the feed end 512 and is used to introduce a first fluid. Specifically, the first fluid is cooling water, and the cooling water is injected from one end and flows out from the other end to form a circulating water path, thereby maintaining this area at a normal temperature. The fluid channel 518 is farther from the feed end 512 than the fluid channel 514 and is used to introduce a second fluid with a temperature higher than the first fluid. Specifically, the second fluid is 80°C liquid oil, and a mold temperature controller (not shown) is used to control the liquid oil at a temperature of 80°C and form a circulating oil path, thereby maintaining this area at a preheating temperature of 80°C. However, in other embodiments, other liquids or gases can also be injected into the fluid channels 514, 518, as long as they can be maintained within a predetermined temperature range lower than the heating temperature of the heating module 52.

The rubber channel 515 is connected to the tube channel 511 and is used for the polyvinyl chloride dipping liquid S to pass through, so that the polyvinyl chloride dipping liquid S is squeezed and coated on the primer layer 91 of the metal tube 9 to form the plastic layer 92. The rubber channel 515 of the first embodiment has two injection ports 517 (only one is shown in the figure) opened to the surrounding environment, so it is suitable for the metal tube 9 with a smaller diameter. If the diameter of the metal tube 9 is smaller or larger, a mold with one or four injection ports 517 can be selected. The mold 5 can be designed with different numbers of injection ports 517 according to the diameter of the metal tube 9.

The air-cooling barrier 519 is formed on the outer peripheral surface and is located between the adhesive channel 515 and the fluid channel 518. The air-cooling barrier 519 is used to block the heat transfer of the fluid channel 518 to the adhesive channel 515. Specifically, the air-cooling barrier 519 is a heat dissipation fin.

The heating module 52 is disposed at the discharge end 513 and is used to heat the plastic layer 92 and pre-curing the plastic layer 92. The heating module 52 of the first embodiment is a heating plate wrapped around the discharge end 513 and adjacent to the fluid channel 518. In order to control the temperature of the heating module 52 to maintain at 160-170°C, a thermocouple 53 for controlling the temperature is disposed inside the heating module 52.

It should be particularly noted that since the polyvinyl chloride dipping liquid S will begin to undergo a crosslinking reaction and gradually solidify at a temperature higher than a specific range (e.g., 160-170° C.), in order to allow the polyvinyl chloride dipping liquid S to maintain its fluidity before being coated on the metal tube 9, the rubber channel 515 is designed between the fluid channels 514 and 518. By designing the fluid channel 514 and the air-cooled barrier zone 519, the polyvinyl chloride dipping liquid S in the rubber channel 515 can be kept in a liquid state and flow smoothly. The preheating of the fluid channel 518 can gradually transform the polyvinyl chloride dipping liquid S near the outlet of the rubber channel 515 into a semi-solidified but still flowable state. Finally, the polyvinyl chloride dipping liquid S begins to solidify by high temperature heating of the heating module 52.

4 to 6 , the sol supply device 6 is connected to the mold 5 through a pipeline 81 and is used to inject the polyvinyl chloride dipping solution S into the mold 5. The sol supply device 6 has a sol storage cylinder 61, a driving unit 62, a diverter valve 63 and a supply unit 64.

The rubber storage cylinder 61 is used to load the polyvinyl chloride dipping liquid S and has a cylinder body 611 in fluid communication with the rubber channel 515 of the mold 5, and a piston 612 movably disposed in the cylinder body 611. Specifically, the cylinder body 611 is made of a seamless steel pipe through honing, and the piston 612 has a sealing ring 613 for fluid sealing, and is also formed with an exhaust valve 614 and a discharge valve 615. The sealing ring 613 is a kind of inner tube and is flat and is sealed to the inner surface of the cylinder body 611 by tension, which can reduce the pushing resistance and withstand high pressure.

The driving unit 62 is connected to the piston 612 of the rubber storage cylinder 61 and is used to drive the piston 612 to move up and down to squeeze the polyvinyl chloride dipping liquid S and inject it into the rubber channel 515 of the mold 5 (see Figure 2). The driving unit 62 has a push rod assembly 621 connected to the piston 612 and a motor assembly 622 used to drive the push rod assembly 621 to move. The push rod assembly 621 has a screw rod 623 connected to the piston 612, two positioning guide pins 627 arranged parallel to the screw rod 623 and connected to the piston 612, and a set of nuts 624 arranged on the screw rod 623 and connected to the motor assembly 622. The screw rod 623 is a trapezoidal guide screw that can rotate forward and reverse, and the nut 624 is a trapezoidal guide nut. The motor assembly 622 is connected to the nut 624 through a belt pulley 628 to drive the screw rod 623 to rotate forward and reverse so that it can move up and down, thereby driving the piston 612 to move. Specifically, the motor assembly 622 has a motor 625 and a speed reducer 626 connected to the motor 625. The motor 625 is a stepper motor. By changing the speed of the speed reducer 626, the transmission torque can be increased so that the polyvinyl chloride dipping liquid S can flow out of the rubber storage cylinder 61 at a constant speed and in a constant amount, thereby providing a stable supply of rubber.

The diverter valve 63 is disposed on the pipeline 81 and is used to divert the polyvinyl chloride dipping liquid S, and then inject it into the glue channel 515 of the mold 5 through the injection ports 517. If the mold 5 has only one injection port 517, the diverter valve 63 can be omitted.

The supply unit 64 is used to automatically supply the polyvinyl chloride dipping solution S into the rubber storage cylinder 61, for example, by using a pneumatic cylinder to automatically supply the rubber storage cylinder 61. In other embodiments, the supply unit 64 can also be omitted, and the rubber storage cylinder 61 can be manually replenished directly.

The following is an explanation of the glue supply method of the glue supply device 6: first open the exhaust valve 614, the driving unit 62 pushes the piston 612 downward to discharge the air in the cylinder body 611, and after the exhaust is complete, the piston 612 stops and the exhaust valve 614 is closed. Open the discharge valve 615, the driving unit 62 starts to push the piston 612 downward to discharge glue from the cylinder body 611. When the polyvinyl chloride dipping solution S in the cylinder body 611 is used up, the piston 612 presses down to the bottom of the cylinder body 611 and touches the micro switch to stop automatically. Next, the piston 612 is rapidly raised to a predetermined position, and the polyvinyl chloride dipping liquid S is replenished to the rubber storage cylinder 61 through the replenishing unit 64, so that the supply of glue can continue.

The first embodiment outputs a larger torque through the transmission ratio design of the motor set 622 without generating a pulsation phenomenon, and is very suitable for extruding the thick fluid-like polyvinyl chloride dipping solution S, so the glue supply of the sol supply device 6 is more stable and smooth. It should be noted that in other variations, two glue storage cylinders 61 can also be provided at the same time to increase the capacity and extend the replenishment time, and the motor 625 can also be a servo motor.

1 and 4 , the baking device 14 is located after the extrusion molding system 200 and is used to heat the metal tube 9 that has passed through the extrusion molding system 200 to completely solidify the plastic layer 92. The baking device 14 of the first embodiment is a hot air circulation oven set at 160°C.

The cooling device 15 is located after the baking device 14 and is used to cool the metal tube 9 having the plastic layer 92 that has passed through the baking device 14. The cooling device 15 of the first embodiment is an annular water spray curtain that can be shortened in length and has the function of cooling the entire tube, thereby shortening the cooling time and reducing the production cycle. However, in other variations, the cooling device 15 can also be a water tank.

The unloading device 16 is located after the cooling device 15 and is used to separate the two connected metal tubes 9. The unloading device 16 of the first embodiment uses a Y-shaped cutter to cut a half circle of the tube joint 8 to separate the two metal tubes 9. However, the unloading method is not limited to this, as long as the connected metal tubes 9 can be separated.

The pipe transverse machines 17 are used to transfer the metal pipes 9 along a direction perpendicular to the feeding path P. Specifically, a pipe transverse machine 17 numbered #1 is provided before the pre-treatment device 11, a pipe transverse machine 17 numbered #2 is provided between the connecting device 13 and the primer device 12, and a pipe transverse machine 17 numbered #3 is provided after the unloading device 16. By utilizing the configuration of the pipe transverse machines 17, the metal pipes 9 can be transported with minimal floor space occupied, thereby reducing the overall length of the equipment on the feeding path P.

Referring to FIG. 1 , FIG. 2 and FIG. 7 , the operation flow of the first embodiment is further described below:

In the surface roughening step 801, the pipe transverse machine 17 numbered #1 and a set of pulleys are used to transfer the metal pipes 9 one by one to the pre-treatment device 11, and the metal pipes 9 are subjected to a surface roughening sandblasting operation.

In the primer step 802 , the primer is rolled onto the outer peripheral surface 902 of the metal tube 9 by the paint applying unit 121 to form the primer layer 91 .

In the primer drying step 803, the drying unit 122 quickly dries the primer layer 91 with a hot air flow at 50°C.

In the connecting step 804, the metal pipes 9 are transferred to the connecting device 13 via the pipe transverse machine 17 numbered #2, and each pipe joint 8 is plugged into every two metal pipes 9 by using the connecting device 13, so that the metal pipes 9 are connected in series.

In the preheating step 805, the conveyor belts 31 of the feeding device 3 are used to clamp each of the metal tubes 9 and pass through the heaters 41. The heaters 41 numbered #1 to #4 are set to 300°C, 275°C, 250°C, and 200°C, respectively. The time from each of the metal tubes 9 entering the heater 41 numbered #1 to leaving the heater 41 numbered #4 is exactly the reaction time required for the primer layer 91, which is 10 minutes. Therefore, the primer layer 91 of each of the metal tubes 9 has reacted completely after leaving the heater 41 numbered #4, and has reached the absolute activation coating temperature before reaching the extrusion molding system 200. During the moving process, the center of each metal tube 9 is aligned with the axis X of the tube channel 511 of the mold body 51 through the positioning rotating component assemblies 32, so that the metal tube 9 can be continuously transported in a straight line.

In the extrusion molding step 806, as shown in FIG5, the conveyor belts 31 continue to drive the metal tubes 9 toward the mold 5, and the metal tubes 9 are positioned in the center of the mold 5 by using the design of the positioning rotating member set 32 arranged at intervals along the feeding path P, which can reduce the pushing resistance of the conveyor belts 31 and make the coating thickness of the plastic layer 92 uniform. The mold 5 forms a normal temperature zone I, a preheating zone II and a high temperature zone III with different temperature ranges according to the design of the fluid channels 514, 518, the air-cooling barrier zone 519 and the heating module 52. The driving unit 62 drives the piston 612 in the rubber storage cylinder 61 to move, and the polyvinyl chloride dipping liquid S is continuously and slowly discharged from the rubber storage cylinder 61 and injected into the rubber channel 515 through the injection ports 517. When each of the metal tubes 9 advances to contact the rubber channel 515, the polyvinyl chloride dipping liquid S will gradually cover the primer layer 91 of each of the metal tubes 9 and form their respective plastic layers 92. The present invention is a single-point in-mold molding, and the amount of the glue discharged from the rubber channel 515 is exactly the total amount of the plastic layer 92, so the amount of the polyvinyl chloride dipping liquid S can be saved. In the normal temperature zone I, the polyvinyl chloride dipping liquid S is at room temperature and is in a liquid flowable state. In the preheating zone II, the polyvinyl chloride dipping liquid S is heated to 80°C and is in a semi-cured state and gradually coated on the primer layer 91 of the metal tube 9 to form the plastic layer 92. In the high temperature zone III, each metal tube 9 is heated to 160-170°C by the heating module 52, so that the plastic layer 92 and the heat-reacted primer layer 91 are bridged and bonded to crosslink and begin to solidify. The discharge end 513 uses the design of the heating module 52 as an electric heating forming ring, so that the true roundness of the extrusion molding is good and there is no sag phenomenon. When each of the metal tubes 9 leaves the mold 5, the pre-curing degree of the plastic layer 92 has reached at least 70% to 80%.

In the baking step 807 , each of the metal tubes 9 moves to the baking device 14 after leaving the mold 5 . The baking device 14 is set to 160° C. The plastic layer 92 is completely cured by baking in the baking device 14 .

In the cooling step 808, each of the metal tubes 9 after baking and curing passes through the cooling device 15, so that each of the metal tubes 9 with the plastic layer 92 is cooled down, and the surface of the plastic layer 92 is bright and smooth.

In the pipe cutting and separation step 809, the pipe joint 8 between every two metal pipes 9 is cut by the unloading device 16, thereby producing a single PVC coated pipe 90.

The baking device 14, the cooling device 15 and the unloading device 16 are arranged on the feeding path P, and two metal tubes 9 are connected in series through each pipe joint 8, and the metal tubes 9 can be continuously pushed through the feeding device 3, and the feeding is continuous and uninterrupted. It can be understood that the baking device 14, the cooling device 15 and the unloading device 16 can also be independent of the feeding path P, and use other pushing devices or moving devices to move the metal tubes 9.

The present invention injects the liquid polyvinyl chloride dipping solution S into a sealed mold for PVC coating, and produces the solidified plastic layer 92, while combining the advantages of injection molding and extrusion molding. The present invention is a single-point coated in-mold molding, which can prevent the sag phenomenon and save the amount of the polyvinyl chloride dipping solution S. The film thickness of the plastic layer 92 is uniform, the roundness is good, and no operating exhaust gas is generated. Therefore, it has the advantages of stable quality and a more environmentally friendly process, so it can indeed achieve the purpose of this invention. In addition, when the present invention is in operation, each of the metal tubes 9 will only move in a straight line and will not rotate. Therefore, in addition to being applicable to round tubes, the present invention can also be applicable to square tubes or other pipe fittings, as long as they are pipe fittings with uniform cross-sectional areas. The shape of the metal tube 9 is not limited, so the applicability of the present invention is good.

Referring to FIG. 8 , the second embodiment of the present invention is similar to the first embodiment, and the difference is that:

The mold body 51 of the mold 5 also has an exhaust channel 516 between the rubber channel 515 and the fluid channel 514. The exhaust channel 516 is used to connect an external vacuum pump and form a negative pressure environment in the tube channel 511 to increase the coverage of the polyvinyl chloride dipping liquid S and the metal tube 9. The exhaust channel 516 has two exhaust ports opened to the surrounding environment, but is not limited thereto.

The mold body 51 omits the air-cooling barrier zone 519 (see FIG. 2 ) and cooling water is introduced into the fluid channel 518 . The fluid channels 514 and 518 are used to block the heat source from transferring heat energy to the rubber channel 515 . Similarly, the polyvinyl chloride dipping liquid S in the rubber channel 515 can be kept in a flowable state, and the mold 5 can form the normal temperature zone I, the preheating zone II and the high temperature zone III.

Referring to FIG. 9 , the third embodiment of the present invention is similar to the second embodiment, and the difference is that:

The exhaust channel 516 of the mold body 51 has only one exhaust port.

The fluid channel 518 has two oil inlets 5181 and two oil outlets 5182. The two-inlet and two-outlet design allows the 80°C liquid oil to be diverted to achieve better temperature distribution. The polyvinyl chloride dipping liquid S in the rubber channel 515 can also be kept in a flowable state, and the mold 5 can form the normal temperature zone I, the preheating zone II and the high temperature zone III.

Referring to FIG. 10 , in a variation, the exhaust channel 516 (see FIG. 9 ) can be omitted, and the polyvinyl chloride dipping liquid S in the rubber channel 515 can also be kept in a flowable state, and the mold 5 can form the normal temperature zone I, the preheating zone II and the high temperature zone III.

In addition, referring to FIG. 11 , which is a variation of the sol supply device 6 , the piston 612 of the sol storage cylinder 61 has two sealing rings 613 , and each of the sealing rings 613 is an O-ring plus a backing ring, which can also achieve the effect of fluid sealing.

However, the above is only an embodiment of the present invention and should not be used to limit the scope of implementation of the present invention. All simple equivalent changes and modifications made according to the scope of the patent application of the present invention and the content of the patent specification are still within the scope of the present patent.

11: Pretreatment device 111: Roughening unit 112: Blower unit 113: Wind cutting chamber 114: Vacuum cleaner 12: Primer device 120: Primer liquid 121: Paint unit 122: Air drying unit 123: Brush wheel 124: Primer cylinder 125: Air pressure vacuum valve 126: Hot air channel 127: Blower 128: Heater 13: Pipe connection device 14: Baking device 15: Cooling device 16: Unloading device 17: Pipe cross-moving machine 200: Extrusion molding system 3: Feeding device 31: Conveyor belt 32: Positioning rotating member assembly 321: Rotating member 4: Preheating device 41: Heater 5: Mold 51: Mold body 511: Tube channel 512: Feed end 513: Discharge end 514: Fluid channel 515: Glue channel 516: Air extraction channel 517: Glue injection port 518: Fluid channel 5181: Oil inlet 5182: Oil outlet 519: Air cooling barrier 52: Heating module 53: Thermocouple 6: Solvent supply device 61: Glue storage cylinder 611: Cylinder body 612: Piston 613: Sealing ring 614: Exhaust valve 615: Discharge valve 62: Drive unit 621: Push rod assembly 622: Motor assembly 623: Screw 624: Nut 625: Motor 626: Speed reducer 627: Positioning guide column 628: Pulley 63: Diverter valve 64: Supply unit 641: Cylinder 8: Pipe joint 81: Pipeline 9: Metal pipe 90: PVC coated pipe 901: Inner surface 902: Outer surface 91: Primer layer 92: Plastic layer L: Length direction P: Feeding path I: Normal temperature zone II: Preheating zone III: High temperature zone S: PVC dipping liquid X: Axis

Other features and effects of the present invention will be clearly presented in the embodiments with reference to the drawings, in which: Figure 1 is a schematic diagram of a first embodiment of the extrusion molding equipment of the present invention for coating a metal tube with polyvinyl chloride dipping liquid; Figure 2 is a cross-sectional view illustrating a mold of an extrusion molding system of the first embodiment; Figure 3 is a partial enlarged view of Figure 1, illustrating a pre-treatment device and a primer device of the first embodiment; Figure 4 is a partial enlarged view of Figure 1, illustrating the extrusion molding system, a baking device and a cooling device; Figure 5 is an action schematic diagram of a sol supply device of the first embodiment; Figure 6 is a top view of the sol supply device; Figure 7 is a flow chart illustrating the operation process of the first embodiment; Figure 8 is a cross-sectional view of the mold of a second embodiment of the present invention; FIG. 9 is a cross-sectional view of the mold of a second embodiment of the present invention; FIG. 10 is a cross-sectional view similar to FIG. 9, illustrating a variation of the mold of the third embodiment; and FIG. 11 is a cross-sectional view illustrating a variation of the sol supply device.

11: Pre-processing device

12: Primer device

121:Painting unit

122: Air drying unit

13: Take over the device

14: Baking device

15: Cooling device

16: Unloading device

17: Pipe Horizontal Moving Machine

200: Extrusion molding system

3: Feeding device

31: Conveyor belt

32: Positioning rotating parts assembly

4: Preheating device

41: Heater

5: Mould

6: Sol supply device

8: Pipe joint

9:Metal pipe

90: PVC coated pipe

P: Feeding path

Claims (10)

An extrusion molding device for coating a metal tube with polyvinyl chloride dipping liquid, comprising: a primer device, including a painting unit, the painting unit is used to coat a primer layer on the outer peripheral surface of the metal tube; and an extrusion molding system, used to extrude the polyvinyl chloride dipping liquid to coat the primer layer of the metal tube to form a plastic layer, the extrusion molding system is arranged along a feeding path and includes: a feeding device, used to drive the metal tube to move and generate a thrust force for the metal tube to move along the feeding path, so that the metal tube with the primer layer can move along the feeding path, a preheating device, located on the feeding path and used to heat the metal tube with the primer layer, A mold is located on the feeding path and adjacent to the preheating device. The mold is used to extrude the polyvinyl chloride dipping liquid to coat the primer layer of the metal pipe to form the plastic layer. The mold has a mold body and a heating module arranged on the mold body. The mold body defines a pipe channel surrounding an axis and for the metal pipe to pass through. The mold body has an inlet end adjacent to the preheating device, an inlet end opposite to the inlet end on the feeding path, and a heating module arranged on the mold body. The material end of the material end is provided with a discharge end, two fluid channels surrounding the axis and between the feed end and the discharge end, and a rubber channel surrounding the axis and between the fluid channels, the fluid channels are used to pass the fluid that blocks the heat source, the rubber channel is connected to the tube channel space and is used to extrude the polyvinyl chloride dipping liquid and coat it on the primer layer of the metal tube, the heating module is arranged at the discharge end and is used to heat the plastic layer and make the plastic layer initially solidified, and a sol supply device, having at least one rubber storage cylinder for loading the polyvinyl chloride dipping liquid, and a driving unit connected to the at least one rubber storage cylinder, the driving unit is used to inject the polyvinyl chloride dipping liquid into the rubber channel of the mold. The extrusion molding equipment for coating a metal tube with polyvinyl chloride dipping liquid as described in claim 1 also includes a pre-treatment device for roughening the outer peripheral surface of the metal tube, and the painting unit applies the primer layer on the roughened outer peripheral surface of the metal tube. An extrusion molding device for coating a metal tube with polyvinyl chloride dipping liquid as described in claim 1, wherein the feeding device has at least two conveyor belts symmetrically arranged on two opposite sides of the feeding path, and a plurality of positioning rotating member groups spaced apart along the feeding path, the conveyor belts are used to clamp the metal tube and generate the thrust force on the metal tube, and each of the positioning rotating member groups has two rotating members for the metal tube to slide through. As described in claim 1, the extrusion molding equipment for coating a metal tube with polyvinyl chloride dipping liquid, wherein the preheating device has a plurality of heaters, and the heating temperature of the heaters decreases as the feeding path advances. The extrusion molding equipment for coating a metal tube with polyvinyl chloride dipping liquid as described in claim 1 also includes a baking device, a cooling device and a unloading device arranged after the extrusion molding system, the baking device is used to heat the metal tube that has passed through the extrusion molding system to solidify the plastic layer, the cooling device is used to cool the metal tube with the plastic layer that has passed through the baking device, and the unloading device is used to separate the two connected metal tubes. A mold for a polyvinyl chloride dipping liquid extrusion molding device, suitable for extruding and coating the polyvinyl chloride dipping liquid on a metal tube, the mold for the polyvinyl chloride dipping liquid extrusion molding device comprises: A mold body, which defines a tube channel surrounding an axis and through which the metal tube passes along a feeding path, and has an inlet end, an outlet end opposite to the inlet end, two fluid channels surrounding the axis and between the inlet end and the outlet end, and a rubber channel surrounding the axis and between the fluid channels, the fluid channels are used to pass a fluid that blocks a heat source, the rubber channel is connected to the tube channel space and is used to extrude the polyvinyl chloride dipping liquid to coat the metal tube to form the plastic layer; and a heating module, which is arranged at the outlet end of the mold body and is used to heat the plastic layer and initially solidify the plastic layer. A mold of a polyvinyl chloride liquid extrusion molding device as described in claim 6, wherein one of the fluid channels of the mold body is adjacent to the feed end and is used to introduce a first fluid, and the other fluid channel is adjacent to the heating module and is used to introduce a second fluid having a temperature higher than that of the first fluid and a temperature lower than that of the heating module. A polyvinyl chloride dipping liquid extrusion molding system is suitable for extruding the polyvinyl chloride dipping liquid to coat a metal tube. The polyvinyl chloride dipping liquid extrusion molding system comprises: A feeding device, used to drive the metal tube to move and generate a thrust force for the metal tube to move along a feeding path, so that the metal tube can move along the feeding path; A preheating device, located on the feeding path and used to heat the metal tube; A mold is located on the feeding path and adjacent to the preheating device. The mold is used to extrude the polyvinyl chloride dipping liquid to coat the metal tube to form the plastic layer. The mold has a mold body and a heating module arranged on the mold body. The mold body defines a pipe channel surrounding an axis and for the metal tube to pass through. The mold body has an inlet end adjacent to the preheating device, an inlet end opposite to the inlet end on the feeding path, and a heating module arranged on the mold body. The material end of the mold includes a discharge end, two fluid channels surrounding the axis and between the feed end and the discharge end, and a rubber channel surrounding the axis and between the fluid channels, the fluid channels are used to pass fluid that blocks the heat source, the rubber channel is connected to the tube channel space and is used to extrude the polyvinyl chloride dipping liquid to coat the metal tube, the heating module is arranged at the discharge end and is used to heat the plastic layer and initially solidify the plastic layer; and a sol supply device, having at least one rubber storage cylinder for loading the polyvinyl chloride dipping liquid, and a driving unit connected to the at least one rubber storage cylinder, the driving unit is used to inject the polyvinyl chloride dipping liquid into the rubber channel of the mold. A polyvinyl chloride dipping liquid extrusion molding system as described in claim 8, wherein the at least one rubber storage cylinder has a cylinder body connected to the rubber channel fluid of the mold, and a piston movably disposed in the cylinder body, the driving unit is used to drive the piston to move so that the polyvinyl chloride dipping liquid is injected into the rubber channel of the mold, and the piston has at least one sealing ring for fluid sealing. A polyvinyl chloride liquid extrusion molding system as described in claim 8, wherein the driving unit has a push rod group corresponding to the at least one storage cylinder and connected to the piston, and a motor group for driving the push rod group, and the motor group drives the push rod group to move to drive the piston to move linearly.

Images