Plastic pipe manufacturing process

Abstract

The application discloses a plastic pipe manufacturing process, which comprises the following steps: preparing plastic powder and a plastic pipe mold; applying positive electricity to a half cavity, spraying the plastic powder into the half cavity through an electrostatic spray gun, so that the plastic powder is adsorbed into the half cavity; heating the plastic powder in the half cavity, after the plastic powder in the half cavity turns into a molten state, closing two half molds to form a plastic pipe blank in the plastic pipe cavity; heating the plastic pipe blank, after the plastic pipe blank reaches a preset temperature, applying a closed preset air pressure to the plastic pipe blank, stopping heating the plastic pipe blank after maintaining for a preset time, cooling the plastic pipe blank, and obtaining a formed plastic pipe. When the plastic pipe is manufactured, the scheme can reduce waste of the plastic powder, and thus improves the raw material utilization rate.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of plastic pipe, in particular, to a plastic pipe manufacturing process. BACKGROUND

[0002] Plastic processing is a general term for various processes of converting synthetic resins or plastics into plastic products, mainly including plastic material batching, plastic molding, plastic part joining, plastic part assembly, machining and surface finishing, among which, plastic molding is a process of making plastic in various forms (powder, granules, solution and dispersion) into products or blanks in the required shape.

[0003] Common methods of plastic molding include extrusion molding, injection molding, calendering, blow molding and thermoforming, etc., extrusion molding, also known as extrusion, refers to a processing method in which the material is continuously pushed forward by the screw while being heated and plasticized between the barrel and screw of the extruder, and then passes through the die head to form various cross-section products or semi-products, injection molding refers to a plastic processing method in which plastic is injected into the mold cavity of a closed mold after being plasticized in the heated barrel of an injection molding machine to form a product.

[0004] The products or blanks prepared by the above-mentioned plastic molding method include excess material, on the one hand, the excess material causes waste of material and reduces material utilization, on the other hand, the excess material needs to be removed, which increases the processing cost. SUMMARY

[0005] The embodiments of the present application provide a plastic pipe manufacturing process, when preparing a plastic pipe, the cavity position of the mold is conductive and the other positions are insulating, the plastic powder is adsorbed on the cavity position of the mold, and the other positions do not adsorb plastic powder, which can reduce the waste of plastic powder and further improve the utilization rate of raw materials.

[0006] Other characteristics and advantages of the present application will become apparent from the following detailed description, or will be learned by practice of the present application.

[0007] According to a first aspect of the embodiments of the present application, a plastic pipe manufacturing process is provided, comprising:

[0008] Preparation of plastic powder and plastic pipe mold, the plastic powder includes an antistatic agent, the plastic pipe mold is composed of two half molds, the half mold includes a half cavity, the half cavity of the half mold is conductive and the other parts are insulating, the half cavity of the half mold and the corresponding half cavity of the other half mold constitute a plastic pipe cavity;

[0009] Apply positive electricity to the half cavity, spray plastic powder into the half cavity through an electrostatic spray gun, and the plastic powder is adsorbed into the half cavity;

[0010] heating the plastic powder in the half-mold cavity, after the plastic powder in the half-mold cavity becomes in a molten state, closing the two half-molds to form a plastic pipe blank in the plastic pipe cavity;

[0011] heating the plastic pipe blank, after the plastic pipe blank reaches a preset temperature, applying a closed preset air pressure to the plastic pipe blank, maintaining for a preset time, stopping heating the plastic pipe blank, and cooling the plastic pipe blank to obtain a formed plastic pipe.

[0012] In some embodiments of the present application, based on the foregoing scheme, the applying positive electricity to the half-mold cavity comprises:

[0013] applying positive electricity to the half-mold cavity according to a preset charge amount, the preset charge amount being determined by a preset thickness of the plastic pipe and a surface area of the plastic pipe.

[0014] In some embodiments of the present application, based on the foregoing scheme, the preset charge amount is proportional to the preset thickness of the plastic pipe, and the preset charge amount is proportional to the surface area of the plastic pipe.

[0015] In some embodiments of the present application, based on the foregoing scheme, the spraying the plastic powder into the half-mold cavity by the electrostatic spray gun comprises:

[0016] injecting the plastic powder into a powder spraying device, and spraying the plastic powder into the half-mold cavity by an electrostatic spray gun of the powder spraying device.

[0017] In some embodiments of the present application, based on the foregoing scheme, after the plastic powder is adsorbed into the half-mold cavity, the plastic powder on other parts of the half-mold is removed.

[0018] In some embodiments of the present application, based on the foregoing scheme, the heating the plastic powder in the half-mold cavity is performed by infrared baking of the half-mold cavity and / or mold heating.

[0019] In some embodiments of the present application, based on the foregoing scheme, the heating the plastic pipe blank is performed by heating the mold and / or circulating hot air flow into the plastic pipe blank.

[0020] In some embodiments of the present application, based on the foregoing scheme, the cooling the plastic pipe blank is performed by circulating cold air flow into the plastic pipe blank.

[0021] In some embodiments of the present application, based on the foregoing scheme, the plastic pipe comprises a plurality of layers of plastic pipes distributed from outside to inside.

[0022] In some embodiments of the present application, based on the foregoing scheme, the applying positive electricity to the half-mold cavity and the spraying the plastic powder into the half-mold cavity by the electrostatic spray gun comprise:

[0023] The positive electricity is applied to the corresponding half-cavity position of the split plastic tube in sequence from the outside to the inside of the split plastic tube, and the plastic powder required by the split plastic tube is sprayed to the corresponding half-cavity position of the split plastic tube through the electrostatic spray gun.

[0024] In some embodiments of the present application, based on the foregoing scheme, the half-cavity comprises a plurality of split cavities distributed in the axial direction, and adjacent split cavities are insulated.

[0025] In some embodiments of the present application, based on the foregoing scheme, the plastic powder further comprises one or more of a plastic raw material, a crosslinking agent and a foaming agent.

[0026] In some embodiments of the present application, based on the foregoing scheme, when the plastic powder comprises a plastic raw material and an antistatic agent, and does not comprise a crosslinking agent and a foaming agent, the preparation of the plastic powder comprises:

[0027] The antistatic agent is mixed into the plastic raw material particles to obtain a first mixture;

[0028] After the first mixture is densified, a first plastic powder is obtained.

[0029] In some embodiments of the present application, based on the foregoing scheme, when the plastic powder comprises a plastic raw material, an antistatic agent, a crosslinking agent and a foaming agent, the preparation of the plastic powder comprises:

[0030] The antistatic agent, the crosslinking agent and the foaming agent are mixed into the plastic raw material particles to obtain a second mixture;

[0031] The second mixture is heated to a molten state to obtain a second molten mixture;

[0032] After the second molten mixture is densified, a second plastic powder is obtained by extrusion.

[0033] In some embodiments of the present application, based on the foregoing scheme, when the plastic powder comprises a plastic raw material, an antistatic agent, a crosslinking agent and a foaming agent, the preset temperature is the foaming temperature required by the plastic tube.

[0034] In some embodiments of the present application, based on the foregoing scheme, the foaming ratio of the plastic tube is controlled by controlling the content of the foaming agent in the plastic powder.

[0035] In some embodiments of the present application, when the plastic tube is prepared, the plastic tube cavity is conductive, the parting surface is insulated, the plastic powder is adsorbed in the plastic tube cavity, and the plastic powder is not adsorbed at other positions, i.e. the parting surface, which can reduce the waste of plastic powder, thereby improving the utilization rate of raw materials, and the thickness of the plastic tube can be controlled by the preset charge amount.

[0036] The beneficial effects of the present application are as follows:

[0037] Firstly, raw materials needed for making plastic tubes, i.e. preparing plastic powder, and devices needed for making plastic tubes, i.e. preparing plastic tube molds, are prepared. The plastic tube mold has only half cavity conductive, and other parts such as parting surface are insulated. Secondly, positive electricity is applied to the half cavity, i.e. the half cavity is positively charged. When the plastic powder is sprayed to the half cavity through the electrostatic spray gun, the plastic powder sprayed by the electrostatic spray gun is negatively charged. The negatively charged plastic powder is adsorbed to the surface of the positively charged half cavity. Since the plastic tube mold has no electricity conduction in other parts except the half cavity, the other parts do not adsorb the negatively charged plastic powder. Finally, the half cavity of the plastic tube mold adsorbs the negatively charged plastic powder, and the other parts do not adsorb the negatively charged plastic powder. Even if there is a small amount of plastic powder attached to the other parts, the plastic powder can be poured out by turning over, because the other parts and the attached plastic powder have no charge adsorption force. Again, the plastic powder adsorbed in the half cavity is heated. When the plastic powder adsorbed in the half cavity becomes a molten state, it becomes a molten plastic. The molten plastic and the half cavity have a cohesive force and a charge adsorption force, so that the molten plastic can be more firmly attached to the surface of the half cavity to form a half plastic tube blank. After the two half molds are closed, the two half plastic tube blanks can form a complete plastic tube blank in the plastic tube cavity. Finally, the plastic tube blank is heated. After the plastic tube blank reaches the preset temperature, a closed preset air pressure is applied to the plastic tube blank, so that the plastic tube blank is tightly attached to the surface of the half cavity. After maintaining for a preset time, the heating of the plastic tube blank is stopped, and the plastic tube blank is cooled to obtain a formed plastic tube. In the process of making the plastic tube, only the forming area, i.e. the half cavity, has plastic powder, and the other parts outside the forming area, i.e. the non-forming area, have no plastic powder. At present, the waste of raw materials mainly occurs in the non-forming area, such as the position close to the forming area. The non-forming area has no plastic powder, which means that the plastic tube made by the present application can reduce the waste of plastic powder, thereby improving the utilization rate of raw materials.

[0038] It should be understood that the above general description and the following detailed description are only exemplary and explanatory, and cannot limit the present application. BRIEF DESCRIPTION OF DRAWINGS

[0039] The drawings herein are incorporated into the specification and form part of the specification, show embodiments consistent with the present application, and together with the specification serve to explain the principles of the present application. Obviously, the drawings in the following description are only some embodiments of the present application, and other drawings can be obtained from these drawings without creative labor for those skilled in the art. In the drawings:

[0040] Figure 1 A flow chart of the plastic tube manufacturing process in the embodiment of the present application is shown;

[0041] Figure 2 A schematic diagram of a foamed duct in an embodiment of the application is shown;

[0042] Figure 3 A schematic diagram of a half-mould body in an embodiment of the application is shown;

[0043] Figure 4 A schematic diagram of a block in an embodiment of the application is shown;

[0044] Figure 5 A schematic diagram of a half-mould in an embodiment of the application is shown;

[0045] Figure 6 and Figure 7 A schematic diagram of a plug in an embodiment of the application is shown. DETAILED DESCRIPTION

[0046] The technical solutions in the embodiments of the present application will be apparently and completely described below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all the embodiments of the present application. Based on the embodiments in the present application, all the other embodiments obtained by a person of ordinary skill in the art without any creative effort fall within the protection scope of the present application.

[0047] In addition, the described features, structures or characteristics can be combined in any suitable way in one or more embodiments. In the following description, numerous specific details are provided to give a sufficient understanding of the embodiments of the present application. However, a person of ordinary skill in the art will realize that the technical solutions of the present application can be practiced without one or more of the specific details, or can employ other methods, components, devices, steps, etc. In other cases, well-known methods, devices, implementations or operations are not shown or described in detail to avoid obscuring the aspects of the present application.

[0048] The block diagrams shown in the drawings are only functional entities, and do not necessarily correspond to physically independent entities. That is, the functional entities can be implemented in the form of software, or implemented in one or more hardware modules or integrated circuits, or implemented in different networks and / or processor devices and / or microcontroller devices.

[0049] The flowcharts shown in the drawings are only exemplary illustrations, and do not necessarily include all the contents and operations / steps, nor necessarily executed in the described order. For example, some operations / steps can be further decomposed, and some operations / steps can be combined or partially combined, so that the actual execution order can be changed according to the actual situation.

[0050] In the description of the present application, it should be understood that the terms "first", "second" are only for the purpose of description, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first", "second" can be explicitly or implicitly included one or more of the features. In the description of the present application, unless otherwise stated, the meaning of "a plurality of" is two or more.

[0051] Figure 1 The flow chart of the plastic pipe manufacturing process in the embodiment of the present application is shown, referring to Figure 1 The plastic pipe manufacturing process at least includes S1 to S4, which are described in detail as follows:

[0052] In step S1, plastic powder and plastic pipe mold are prepared, the plastic powder includes antistatic agent, the plastic pipe mold is composed of two half molds, the half mold includes half cavity, the half cavity of the half mold is conductive and the other parts are insulated, and the half cavity of the half mold and the half cavity of the corresponding position of the other half mold constitute the plastic pipe cavity.

[0053] Specifically, the plastic powder can be prepared according to the material manufacturing requirements of the plastic pipe, such as including foaming agent or not, the plastic pipe is cut into two local plastic pipes along the axial direction, the local plastic pipe can be half of the plastic pipe or a part of the plastic pipe, the shape of the half cavity matches the local shape of the local plastic pipe, and the shape of the plastic pipe cavity matches the shape of the plastic pipe. The other parts of the half mold, such as the parting surface, can be provided with capillary exhaust holes, which can be strip-shaped holes.

[0054] In step S2, the half cavity is positively charged, and the plastic powder is sprayed into the half cavity by the electrostatic spray gun, so that the plastic powder is adsorbed into the half cavity.

[0055] Specifically, the plastic powder sprayed by the electrostatic spray gun is negatively charged, the half cavity is positively charged, and the negatively charged plastic powder is adsorbed to the inner wall of the half cavity.

[0056] In step S3, the plastic powder in the half cavity is heated, and after the plastic powder in the half cavity becomes a molten state, the two half molds are closed, and the plastic pipe cavity forms a plastic pipe blank.

[0057] Specifically, after the plastic powder in the half cavity becomes a molten state, a half plastic pipe blank is obtained, and after the two half molds are closed, the two half plastic pipe blanks form a complete plastic pipe blank.

[0058] In step S4, the plastic pipe blank is heated, and after the plastic pipe blank reaches a preset temperature, a closed preset air pressure is applied to the plastic pipe blank, and after a preset time is maintained, the heating of the plastic pipe blank is stopped, and the plastic pipe blank is cooled to obtain a formed plastic pipe.

[0059] Specifically, a closed preset air pressure is applied to the plastic tube blank, so that the plastic tube blank is tightly attached to the inner wall of the plastic tube cavity, and after a preset time, the heating of the plastic tube blank is stopped, and the plastic tube blank is cooled, so that a molded plastic tube product is obtained. The preset temperature, the preset air pressure and the preset time can be obtained according to the production requirements of the plastic tube, or can be preset. The preset temperature can be set according to the blow molding temperature, or can be set according to the foaming temperature.

[0060] Optionally, after step S4, the following steps can also be included:

[0061] Open the two half-molds, and remove the plastic tube in the plastic tube cavity.

[0062] In the present application, the application of positive electricity to the half-cavity includes:

[0063] According to a preset charge amount, positive electricity is applied to the half-cavity, and the preset charge amount is determined by the plastic tube preset thickness and the plastic tube surface area. The preset charge amount is directly proportional to the plastic tube preset thickness, and the preset charge amount is directly proportional to the plastic tube surface area.

[0064] Specifically, when the half-cavity is positively charged according to the preset charge amount, the thickness of the plastic powder adsorbed on the half-cavity reaches the preset thickness, and the amount of plastic powder adsorbed on the half-cavity is the product of the plastic tube surface area and the plastic tube preset thickness. According to the preset charge amount, when the charge amount of the plastic powder accumulated on the half-cavity increases to a certain extent, the charge amount reaches the preset charge amount, and the plastic powder adsorbed on the half-cavity generates electrostatic repulsion. The half-cavity no longer adsorbs new plastic powder. Even if a small amount of new plastic powder is sprayed into the half-cavity, the excess plastic powder can be removed by turning over the half-mold, so that the half-cavity surface forms a plastic powder with a preset thickness. Therefore, the thickness of the plastic powder adsorbed on the half-cavity can be controlled by controlling the preset charge amount, that is, the thickness of the plastic tube can be controlled.

[0065] It can be understood that for a plurality of plastic tubes with the same plastic tube surface area, the greater the plastic tube preset thickness, the greater the preset charge amount. For a plurality of plastic tubes with the same plastic tube preset thickness, the greater the plastic tube surface area, the greater the preset charge amount.

[0066] In the present application, the application of positive electricity to the half-cavity includes:

[0067] The plastic powder is injected into the powder injection device, and the plastic powder is sprayed into the half cavity through the electrostatic spray gun of the powder injection device. The electrostatic spray gun comprises an electrostatic generator and a nozzle. The plastic powder is sprayed out of the nozzle after passing through the electrostatic generator. The electrostatic generator generates an electric field force, so that the plastic powder passing through the electrostatic generator is negatively charged. Therefore, the plastic powder sprayed out of the nozzle is negatively charged. When the negatively charged plastic powder is sprayed out of the nozzle, the positively charged half cavity will attract the negatively charged plastic powder to the surface of the half cavity.

[0068] In the present application, after the plastic powder is adsorbed into the half cavity, the plastic powder on other parts of the half mold is removed to avoid affecting the accuracy of the mold closing and causing waste of raw materials. The other parts of the half mold include the parting surface. If there is plastic powder on the parting surface, a gap will exist between the two half molds during mold closing, which is not conducive to the better adhesion of the two half molds and affects the accuracy of mold closing. Therefore, removing the plastic powder on the parting surface enables the two half molds to better adhere to each other, ensuring the forming quality of the plastic pipe. Since the parting surface is insulating, i.e. non-conductive, the parting surface does not adsorb plastic powder. The half mold can be turned over so that the plastic powder falling on the parting surface falls off. At this time, the plastic powder on the conductive half cavity part is adsorbed on the surface of the half cavity. The plastic powder falling on the parting surface can also be blown off by a slight airflow.

[0069] In the present application, the plastic powder in the half cavity is heated by infrared baking of the half cavity and / or mold heating.

[0070] In the present application, the plastic pipe blank is heated by heating the mold and / or circulating hot air flow into the plastic pipe blank.

[0071] In the present application, the plastic pipe blank is cooled by circulating cold air flow into the plastic pipe blank.

[0072] Specifically, when circulating hot air flow or circulating cold air flow is introduced into the plastic pipe blank, the same air inlet and air outlet can be used, or different air inlets and air outlets can be used.

[0073] In the present application, the plastic pipe comprises a plurality of layers of sub-plastic pipes distributed in turn from the outside to the inside.

[0074] In the present application, the half cavity is positively charged by the electrostatic spray gun, and the plastic powder is sprayed into the half cavity.

[0075] According to the order of the sub-plastic pipes from the outside to the inside, the corresponding half cavity positions of the sub-plastic pipes are positively charged in turn, and the required plastic powder of the sub-plastic pipes is sprayed into the corresponding half cavity positions of the sub-plastic pipes by the electrostatic spray gun.

[0076] Specifically, the corresponding half-cavity position of the split plastic tube can be applied with positive electricity according to the preset thickness and surface area of the split plastic tube and the corresponding preset electric charge amount. The principle of applying positive electricity to the half-cavity is the same. The required plastic powder of the split plastic tube distributed from the outside to the inside can be the same or different. The split plastic tube can correspond to one layer of the plastic tube with a composite layer. Therefore, the plastic tube manufacturing process of the present application can be used to manufacture a plastic tube with a composite layer. For example, the plastic tube includes two layers, the outer layer is made of plastic powder, and the inner layer is made of plastic powder containing a foaming agent.

[0077] In the present application, the half-cavity includes a plurality of split cavities distributed along the axial direction, and adjacent split cavities are insulated. Positive electricity can be applied to a single split cavity or a plurality of split cavities at the same time. For example, there are two split cavities A and B. Positive electricity can be applied to split cavity A or split cavity B separately, or to split cavity A and split cavity B at the same time.

[0078] In the present application, the plastic powder further includes one or more of a plastic raw material, a crosslinking agent, and a foaming agent.

[0079] Specifically, when the plastic powder includes a plastic raw material and an antistatic agent, and does not include a crosslinking agent and a foaming agent, the preparation of the plastic powder includes:

[0080] The antistatic agent is mixed into the plastic raw material particles to obtain a first mixture;

[0081] After the first mixture is densified, a first plastic powder is obtained.

[0082] Specifically, when the plastic powder includes a plastic raw material, an antistatic agent, a crosslinking agent, and a foaming agent, the preparation of the plastic powder includes:

[0083] The antistatic agent, the crosslinking agent, and the foaming agent are mixed into the plastic raw material particles to obtain a second mixture;

[0084] The second mixture is heated to a molten state to obtain a second molten mixture;

[0085] After the second molten mixture is densified, a second plastic powder is obtained by extrusion.

[0086] In the present application, when the plastic powder includes a plastic raw material, an antistatic agent, a crosslinking agent, and a foaming agent, the preset temperature is the foaming temperature required by the plastic tube.

[0087] In the present application, the foaming ratio of the plastic tube is controlled by controlling the content of the foaming agent in the plastic powder.

[0088] Referring to Figure 2 , Figure 2A schematic diagram of the foamed air pipe in the embodiment of the present application is shown, Figure 2 In the embodiment, 1 is the air pipe body, 2 is the air pipe joint, and the air pipe body 1 and the air pipe joint 2 are connected by Figure 2 It can be seen that the foamed air pipe comprises a tubular air pipe body 1 and air pipe joints 2 at both ends of the air pipe body 1, Figure 3 A schematic diagram of the half-mold body in the embodiment of the present application is shown, Figure 4 A schematic diagram of the insert in the embodiment of the present application is shown, Figure 5 A schematic diagram of the half-mold in the embodiment of the present application is shown, referring to Figures 3 to 5 After the half-mold body and the insert are assembled, the half-mold is obtained, and the half-mold body and the insert are insulated, the half-mold is provided with a strip-shaped capillary exhaust hole on the parting surface, and after the two half-molds are closed, a plastic pipe mold, i.e., the foamed air pipe mold in the following example, is formed, referring to Figure 6 and Figure 7 , Figure 6 and Figure 7 A schematic diagram of the plug in the embodiment of the present application is shown, and in order to better understand the embodiment, the foamed air pipe is taken as an example, and the plastic pipe manufacturing process is provided as follows:

[0089] (1) Prepare plastic powder and foamed air pipe mold, the plastic powder comprises an antistatic agent, the foamed air pipe mold is composed of two half-molds, the half-mold comprises a half-cavity, the half-cavity of the half-mold is conductive and other parts are insulated, the half-cavity of the half-mold comprises a half-cavity corresponding to the half-mold body and a half-cavity corresponding to the insert, and the half-cavity of the half-mold and the half-cavity corresponding to the position of the other half-mold constitute a foamed air pipe cavity, the plastic powder comprises first plastic powder and second plastic powder, the second plastic powder is used for preparing the air pipe body, and the first plastic powder and the second plastic powder are used for preparing the air pipe joint. The preparation method of the first plastic powder is as follows: the antistatic agent is mixed into the HDPE raw material particles to obtain a first mixture; after the first mixture is densified, the first plastic powder is obtained. The preparation method of the second plastic powder is as follows: the antistatic agent, the crosslinking agent and the foaming agent are mixed into the polyethylene raw material particles to obtain a second mixture; the second mixture is heated to a molten state to obtain a second molten mixture; after the second molten mixture is densified, the second plastic powder is obtained by extrusion.

[0090] (2) the positive electricity is applied to the half cavity, the plastic powder is sprayed into the half cavity by the electrostatic spray gun, so that the plastic powder is adsorbed into the half cavity, specifically, the positive electricity is applied to the split cavity corresponding to the insert, the first plastic powder is injected into the powder spraying device, the first plastic powder is sprayed into the split cavity corresponding to the insert by the electrostatic spray gun, the first plastic powder is adsorbed to the inner wall of the split cavity corresponding to the insert, the positive electricity is applied to the split cavity corresponding to the half mold body and the split cavity corresponding to the insert, the second plastic powder is injected into the powder spraying device, the second plastic powder is sprayed into the split cavity corresponding to the half mold body and the split cavity corresponding to the insert by the electrostatic spray gun, the second plastic powder is adsorbed to the inner wall of the split cavity corresponding to the half mold body and the split cavity corresponding to the insert, when the positive electricity is applied to the split cavity corresponding to the insert, the preset charge amount is determined according to the preset thickness of the first plastic powder and the surface area of the insert, when the positive electricity is applied to the split cavity corresponding to the half mold body, the preset charge amount is determined according to the preset thickness of the second plastic powder and the surface area of the half cavity.

[0091] (3) the plug is slid to block the end of the half cavity, the first plastic powder and the second plastic powder on the parting surface are removed, the first plastic powder and the second plastic powder in the half cavity are heated, specifically, the infrared baking is performed on the half mold body and the insert, and the half mold is heated, after the first plastic powder and the second plastic powder in the half cavity become a molten state, the two half molds are closed, the foaming air pipe cavity is formed into a foaming air pipe blank, that is, the molding work of the foaming air pipe is completed, at this time, the plug blocks the two ends of the foaming air pipe blank,

[0092] (4) the foaming air pipe blank is heated, specifically, the foaming air pipe mold is heated, the circulating hot air flow is circulated to the foaming air pipe blank through the ventilation hole of the plug, that is, the hot air flow enters the foaming air pipe blank from the ventilation hole of the plug at one end of the foaming air pipe blank, and is discharged from the ventilation hole of the plug at the other end of the foaming air pipe blank, after the foaming air pipe blank reaches a preset temperature, the preset temperature is the foaming temperature required by the foaming air pipe, the foaming air pipe blank is applied with a closed preset air pressure, after a preset time is maintained, the foaming air pipe blank is stopped heating, so that the foaming work of the foaming air pipe is completed, the foaming air pipe blank is cooled to obtain the molded foaming air pipe;

[0093] (5) the two half molds are opened, and the foaming air pipe in the foaming air pipe cavity is taken out.

[0094] In the above example, refer to Figures 3 to 6Five foamed air ducts can be made at the same time, the foamed air duct can be understood as a special type of plastic pipe in the embodiment of the application, the foamed air duct is made by the method of forming first and then foaming, and by controlling the content of the foaming agent, the foaming ratio of the foamed air duct can be controlled, and by using a higher foaming ratio, a lighter foamed air duct can be prepared, and a composite layer pipe wall can be made, such as the air duct joint, the outer layer is non-foamed HDPE, which has sufficient strength and hardness to meet the requirements of multi-section air duct plug-in assembly, and the inner layer is a closed-cell foamed layer which can meet the sealing requirement during plug-in assembly.

[0095] In summary, when preparing the plastic pipe, the plastic pipe cavity is conductive, the parting surface is insulating, the plastic powder is adsorbed in the plastic pipe cavity, and no plastic powder is adsorbed at other positions, i.e., the parting surface, according to the preset thickness of the plastic pipe and the surface of the plastic pipe, a preset charge amount is set, when the plastic powder reaches the preset thickness, the charge amount accumulated by the plastic powder and the preset charge amount reach charge balance, and no new plastic powder is adsorbed, the shape and thickness of the prepared plastic pipe are the required shape and thickness, no cutting processing is required, the waste of plastic powder can be reduced, and the raw material utilization rate is improved, the thickness of the plastic pipe can be controlled by the preset charge amount, the plastic powder is adsorbed to the cavity inner wall by electrostatic adsorption, which can be used for processing complex surfaces and reverse-docking surfaces, and the mold structure is simplified.

[0096] The above only describes the embodiments of the application and is not used to limit the application, for those skilled in the art, the application can have various changes and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the application shall be included in the scope of the claims of the application.

Claims

1. A plastic pipe manufacturing process, characterized in that, include: Prepare plastic powder and plastic tube mold, wherein the plastic powder includes an antistatic agent, and the plastic tube mold consists of two half molds, each half mold including a half cavity, wherein the half cavity of the half mold is conductive and other parts are insulated, and the half cavity of the half mold and the corresponding half cavity of the other half mold constitute the plastic tube cavity; A positive charge is applied to the semi-cavity, and the plastic powder is sprayed into the semi-cavity using an electrostatic spray gun, so that the plastic powder is adsorbed into the semi-cavity. The plastic powder in the half-cavity is heated until it becomes molten. Then the two half-cavities are closed to form a plastic tube blank in the plastic tube cavity. The plastic tube blank is heated. After the plastic tube blank reaches a preset temperature, a closed preset air pressure is applied to the plastic tube blank. After maintaining the pressure for a preset time, the heating of the plastic tube blank is stopped, and the plastic tube blank is cooled to obtain a formed plastic tube.

2. The plastic pipe manufacturing process according to claim 1, characterized in that, Applying a positive charge to the semi-cavity includes: A positive charge is applied to the semi-cavity according to a preset charge amount, which is determined by the preset thickness and surface area of ​​the plastic tube.

3. The plastic pipe manufacturing process according to claim 2, characterized in that, The preset charge amount is proportional to the preset thickness of the plastic tube, and the preset charge amount is proportional to the surface area of ​​the plastic tube.

4. The plastic pipe manufacturing process according to claim 1, characterized in that, After the plastic powder is adsorbed into the cavity of the half mold, the plastic powder is removed from other parts of the half mold.

5. The plastic pipe manufacturing process according to claim 1, characterized in that, The plastic tube comprises multiple layers of plastic tubes distributed sequentially from the outside to the inside.

6. The plastic pipe manufacturing process according to claim 5, characterized in that, Applying a positive charge to the semi-cavity and spraying the plastic powder into the semi-cavity using an electrostatic spray gun includes: Following the order of the plastic tubes from the outside to the inside, positive electricity is applied to the corresponding half-cavity positions of the plastic tubes in sequence, and the required plastic powder is sprayed onto the corresponding half-cavity positions of the plastic tubes using an electrostatic spray gun.

7. The plastic pipe manufacturing process according to claim 6, characterized in that, The half-cavity includes multiple parting cavities distributed along the axial direction, and adjacent parting cavities are insulated from each other.

8. The plastic pipe manufacturing process according to claim 7, characterized in that, When the plastic powder comprises plastic raw materials and antistatic agents, but excludes crosslinking agents and foaming agents, the preparation of the plastic powder includes: An antistatic agent is mixed into plastic raw material granules to obtain the first mixture; After the first mixture is intensively mixed, the first plastic powder is obtained.

9. The plastic pipe manufacturing process according to claim 7, characterized in that, When the plastic powder comprises plastic raw materials, antistatic agents, crosslinking agents, and foaming agents, the preparation of the plastic powder includes: Antistatic agent, crosslinking agent and foaming agent are mixed into plastic raw material granules to obtain a second mixture; The second mixture is heated to a molten state to obtain a second molten mixture; After the second molten mixture is intensively kneaded, it is extruded to obtain the second plastic powder.

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