A polytetrafluoroethylene anti-corrosion plastic forming device

Abstract

The present invention discloses a polytetrafluoroethylene anti-corrosion plastic molding device, which relates to the technical field of plastic molding and includes an injection molding unit, which comprises a feeding assembly, a plurality of heat preservation assemblies sleeved on the outer wall of the feeding assembly, an auxiliary assembly sleeved on the outer wall of the heat preservation assembly, and a feeding assembly fixed at one end of the feeding assembly. The beneficial effects of the present invention are to achieve precise conveying control of preheated PTFE powder and modified PTFE; precisely adjust the material discharge rate by controlling the distance between the screw rod and the injection nozzle, and use the screw pair to control the axial movement of the injection molding assembly in the mold to ensure uniform distribution of the material.

Description

Technical Field

[0001] The present invention relates to the technical field of plastic molding, and in particular to a polytetrafluoroethylene anti-corrosion plastic molding device. Background Art

[0002] Polytetrafluoroethylene (PTFE), as a representative of high-performance engineering plastics, its excellent chemical stability, electrical insulation and high-temperature resistance characteristics have enabled it to be widely used in fields such as aerospace, chemical industry, and electronics. Contemporary PTFE molding technologies mainly include three technical paths: free extrusion method, casting film process and isostatic pressing. The free extrusion process forms a paste by mixing PTFE powder with organic solvents, and forms PTFE products with an oriented structure through extrusion, devolatilization and sintering. This process loosens the grains in the PTFE matrix, forms axial fibrils, and enhances the strength and stiffness of the product, but the process is cumbersome and has a heavy environmental burden. The casting film technology uses a PTFE aqueous dispersion system to coat the surface of the substrate, and realizes crystal melting and inter-particle fusion through sintering. This coating process does not produce molecular orientation and has isotropic characteristics, but it is inefficient and the uneven wall thickness is caused by the sedimentation of PTFE particles in the dispersion liquid. Isostatic pressing compresses PTFE powder under a multi-directional pressure field and then sinters to form a high-density PTFE matrix structure, but this process has high requirements for equipment and is only applicable to products with relatively simple geometric shapes.

[0003] Centrifugal molding, as a potential PTFE processing method, can be used in PTFE powder centrifugal molding process and modified PTFE centrifugal molding process. However, there are multi-dimensional technical limitations in the implementation of centrifugal molding in existing PTFE processing technologies. First, the metering accuracy and pressure stability of the traditional conveying mechanism for modified PTFE materials are insufficient, resulting in a significant density gradient in molding. Second, the axial distribution control mechanism is lacking. During the production of tubular or cylindrical PTFE products, the uneven distribution of materials along the axis directly affects the performance consistency. Third, due to the extremely high viscosity characteristics of PTFE and its modified systems, the conventional displacement control method relying on pressure regulation is difficult to apply, and there is a lack of an effective mechanism to achieve precise displacement regulation. In addition, the energy recycling utilization rate is low, and the high-temperature heat energy required for PTFE sintering is difficult to achieve cascade utilization in traditional equipment. The most crucial thing is that the separation of the molding and surface treatment processes leads to a long process chain. The low surface energy of PTFE makes it difficult for the post-treatment coating to adhere, increasing the production complexity and environmental burden, which is particularly disadvantageous for PTFE products that require anti-corrosion functions. Summary of the Invention

[0004] In view of the problems existing in the above or the prior art, the present invention is proposed.

[0005] Therefore, the object of the present invention is to provide a polytetrafluoroethylene anti-corrosion plastic molding device, which can solve the problems mentioned in the background art.

[0006] To solve the above technical problems, the present invention provides the following technical solutions: A polytetrafluoroethylene anti-corrosion plastic forming device, which includes an injection molding unit, including a feeding assembly, a plurality of heat preservation assemblies sleeved on the outer wall of the feeding assembly, an auxiliary assembly sleeved on the outer wall of the heat preservation assembly, and a feeding assembly fixed at one end of the feeding assembly;

[0007] The feeding assembly includes an injection molding shell, a screw rod sleeved on the inner wall of the injection molding shell, an adjusting head fixed at the end of the screw rod, a spring and a siphon ring respectively sleeved on the outer wall of the adjusting head, and an injection nozzle fixed at the end of the injection molding shell.

[0008] As a preferred solution of the polytetrafluoroethylene anti-corrosion plastic forming device of the present invention, wherein: a moving unit, including a lead screw pair, and a support table fixed on the outer wall of the threaded sleeve of the lead screw pair;

[0009] A driving unit, including a push rod arranged on one side of the support table, a slide rail fixed between the support table and the push rod, a guide block sleeved on the outer wall of the slide rail, and a motor penetrating through one side of the guide block;

[0010] The other end of the injection molding shell is fixedly connected to the surface of the support table, and the screw rod penetrates through the center of the support table and is fixedly connected to the end of the motor shaft.

[0011] As a preferred solution of the polytetrafluoroethylene anti-corrosion plastic forming device of the present invention, wherein: the injection molding shell is cylindrical, including a mounting plate fixed on its outer wall;

[0012] The adjusting head is conical, including a round rod fixed on one side of it, a positioning block fixed on the outer wall of the round rod, and a through groove opened on the outer wall of the adjusting head;

[0013] The injection nozzle is cylindrical, including a tapered opening opened at one end of it.

[0014] As a preferred solution of the polytetrafluoroethylene anti-corrosion plastic forming device of the present invention, wherein: the feeding assembly includes an end cover, and a storage bin fixed on the side wall of the end cover;

[0015] The end cover includes a material gathering cavity arranged inside it; the storage bin is communicated with the material gathering cavity.

[0016] As a preferred solution of the polytetrafluoroethylene anti-corrosion plastic forming device of the present invention, wherein: the heat preservation assembly includes heating coils respectively sleeved on the outer walls of the injection nozzle and the injection molding shell, and a heat preservation shell sleeved on the outside of the heating coils.

[0017] As a preferred embodiment of the polytetrafluoroethylene anti-corrosion plastic molding equipment of the present invention, wherein: the auxiliary assembly includes a mounting ring fixed on one side of the injection nozzle, an atomizing nozzle fixed on the outer wall of the mounting ring, a diversion shell fixed on the mounting plate, a sealing shell fixed on the diversion shell, and a first delivery pipe and a second delivery pipe communicated with the atomizing nozzle.

[0018] As a preferred embodiment of the polytetrafluoroethylene anti-corrosion plastic molding equipment of the present invention, wherein: the diversion shell includes a first inflation nozzle, a first air extraction nozzle and a first liquid injection nozzle opened on its outer wall, a plurality of second inflation nozzles, a plurality of second air extraction nozzles and a plurality of second liquid injection nozzles arranged on one side of the diversion shell, and a plurality of confluence channels and a plurality of one-way channels opened inside the diversion shell.

[0019] As a preferred embodiment of the polytetrafluoroethylene anti-corrosion plastic molding equipment of the present invention, wherein: the first inflation nozzle, the first air extraction nozzle, the first liquid injection nozzle, the second inflation nozzle, the second air extraction nozzle and the second liquid injection nozzle are respectively connected with one-way channels;

[0020] The first inflation nozzle is communicated with each of the second inflation nozzles through one of the confluence channels; the first air extraction nozzle is communicated with each of the second air extraction nozzles through one of the confluence channels; the first liquid injection nozzle is communicated with each of the second liquid injection nozzles through one of the confluence channels.

[0021] The beneficial effects of the present invention: The present invention realizes the precise conveying control of preheating PTFE powder and modified PTFE; precisely adjusts the material discharge by controlling the distance between the screw rod and the injection nozzle; uses the screw pair to control the axial movement of the injection assembly in the mold to ensure uniform distribution of the material; integrates centrifugal technology and vacuum defoaming to improve the material molding quality; reduces energy consumption through heat preservation and improves energy efficiency through waste heat utilization; realizes the process integration of molding and surface treatment, significantly improves the density uniformity and dimensional accuracy of the product, reduces energy consumption, shortens the production cycle, and enhances the anti-corrosion performance of PTFE products. Description of the Drawings

[0022] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following will briefly introduce the drawings required for the description of the embodiments. Obviously, the following drawings are only some embodiments of the present invention. For those of ordinary skill in the art, other drawings can be obtained based on these drawings without creative efforts.

[0023] Figure 1 It is the overall three-dimensional explosion diagram of the present invention.

[0024] Figure 2 It is the explosion diagram of the injection unit of the present invention.

[0025] Figure 3 This is an exploded view of the feeding component of the present invention.

[0026] Figure 4 This is an overall full sectional view of the present invention.

[0027] Figure 5 This is the Figure 4 partial enlarged view in the present invention.

[0028] Figure 6 This is an internal perspective view of the flow guide shell of the present invention.

[0029] Figure 7 This is a schematic diagram of centrifugal molding of the present invention.

[0030] Figure 8 This is an overall three-dimensional view of the present invention.

[0031] In the figure: 1, injection molding unit; 11, feeding component; 12, heat preservation component; 13, auxiliary component; 14, feeding component; 2, moving unit; 21, lead screw pair; 22, support table; 3, driving unit; 31, push rod; 32, slide rail; 33, guide block; 34, motor; 111, injection molding shell; 112, spiral rod; 113, adjusting head; 114, spring; 115, siphon ring; 116, injection nozzle; 1111, mounting plate; 1131, round rod; 1132, positioning block; 1133, through groove; 1161, conical opening; 141, end cover; 142, storage bin; 1411, material gathering cavity; 121, heating coil; 122, heat preservation shell; 131, mounting ring; 132, atomizing nozzle; 133, flow guide shell; 134, sealing shell; 135, first conveying pipe; 136, second conveying pipe; 1331, first inflation nozzle; 1332, first air extraction nozzle; 1333, first liquid injection nozzle; 1334, second inflation nozzle; 1335, second air extraction nozzle; 1336, second liquid injection nozzle; 1337, confluence channel; 1338, one-way channel; 4, mold; 41, sealing port; 42, transmission shaft. Detailed implementation manners

[0032] To make the above objects, features and advantages of the present invention more obvious and understandable, the following will give a detailed description of the specific implementation manners of the present invention with reference to the accompanying drawings of the specification.

[0033] In the following description, many specific details are set forth to fully understand the present invention. However, the present invention can also be implemented in other ways different from this description. Those skilled in the art can make similar extensions without departing from the connotation of the present invention. Therefore, the present invention is not limited by the specific embodiments disclosed below.

[0034] Secondly, the "one embodiment" or "embodiment" referred to herein means a specific feature, structure, or characteristic that may be included in at least one implementation of the present invention. The appearances of "in one embodiment" in different places in this specification do not all refer to the same embodiment, nor are they separate or selectively exclusive embodiments from other embodiments. Embodiment

[0035] Refer to Figures 1 to 8 , which is the first embodiment of the present invention. This embodiment provides a polytetrafluoroethylene anti-corrosion plastic molding device, which includes an injection molding unit 1, including a feeding component 11, several heat preservation components 12 sleeved on the outer wall of the feeding component 11, an auxiliary component 13 sleeved on the outer wall of the heat preservation component 12, and a feeding component 14 fixed at one end of the feeding component 11;

[0036] The feeding component 11 includes an injection molding shell 111, a screw rod 112 sleeved on the inner wall of the injection molding shell 111, an adjustment head 113 fixed at the end of the screw rod 112, a spring 114 and a siphon ring 115 respectively sleeved on the outer wall of the adjustment head 113, and an injection molding nozzle 116 fixed at the end of the injection molding shell 111.

[0037] Furthermore, a moving unit 2, including a lead screw pair 21, and a support platform 22 fixed on the outer wall of the threaded sleeve of the lead screw pair 21;

[0038] A driving unit 3, including a push rod 31 arranged on one side of the support platform 22, a slide rail 32 fixed between the support platform 22 and the push rod 31, a guide block 33 sleeved on the outer wall of the slide rail 32, and a motor 34 penetrating and arranged on one side of the guide block 33;

[0039] The other end of the injection molding shell 111 is fixedly connected to the surface of the support platform 22, and the screw rod 112 penetrates through the center of the support platform 22 and is fixedly connected to the shaft end of the motor 34.

[0040] Furthermore, the injection molding shell 111 is cylindrical, including a mounting plate 1111 fixed on its outer wall;

[0041] The adjustment head 113 is conical, including a round rod 1131 fixed on one side of it, a positioning block 1132 fixed on the outer wall of the round rod 1131, and a through groove 1133 opened on the outer wall of the adjustment head 113;

[0042] The injection molding nozzle 116 is cylindrical, including a conical opening 1161 opened at one end of it.

[0043] Furthermore, the feeding component 14 includes an end cover 141, and a storage bin 142 fixed on the side wall of the end cover 141;

[0044] The end cover 141 includes a material gathering cavity 1411 arranged inside it; the storage bin 142 is communicated with the material gathering cavity 1411.

[0045] Furthermore, the heat preservation component 12 includes heating coils 121 sleeved on the outer walls of the injection nozzle 116 and the injection shell 111 respectively, and a heat preservation shell 122 sleeved outside the heating coils 121.

[0046] Furthermore, the auxiliary component 13 includes a mounting ring 131 fixed to one side of the injection nozzle 116, an atomizing nozzle 132 fixed to the outer wall of the mounting ring 131, a diversion shell 133 fixed to the mounting disc 1111, a sealing shell 134 fixed to the diversion shell 133, and a first delivery pipe 135 and a second delivery pipe 136 communicated with the atomizing nozzle 132.

[0047] Furthermore, the diversion shell 133 includes a first gas injection nozzle 1331, a first air extraction nozzle 1332 and a first liquid injection nozzle 1333 opened on its outer wall, a plurality of second gas injection nozzles 1334, a plurality of second air extraction nozzles 1335 and a plurality of second liquid injection nozzles 1336 arranged on one side of the diversion shell 133, and a plurality of confluence channels 1337 and a plurality of one-way channels 1338 opened inside the diversion shell 133.

[0048] Furthermore, the first gas injection nozzle 1331, the first air extraction nozzle 1332, the first liquid injection nozzle 1333, the second gas injection nozzles 1334, the second air extraction nozzles 1335 and the second liquid injection nozzles 1336 are respectively connected with one-way channels 1338; the first gas injection nozzle 1331 is communicated with each of the second gas injection nozzles 1334 through one of the confluence channels 1337; the first air extraction nozzle 1332 is communicated with each of the second air extraction nozzles 1335 through one of the confluence channels 1337; the first liquid injection nozzle 1333 is communicated with each of the second liquid injection nozzles 1336 through one of the confluence channels 1337.

[0049] It should be noted that the centrifugal molding process has significant technical necessity and process advantages for molding polytetrafluoroethylene PTFE and its modified systems. The centrifugal molding technology makes the PTFE powder or modified PTFE evenly distributed on the inner wall of the mold through the centrifugal force field generated by rotation, solving the key technical defects such as uneven material distribution, wall thickness fluctuation and density gradient in the traditional static pressure molding and casting film processes.

[0050] This process is particularly suitable for the production of axially symmetric PTFE anti-corrosion products such as tubular and cylindrical shapes. The centrifugal force field can provide a uniform pressing force matching the geometric shape of the mold, significantly improving the uniformity of the material in the axial and radial directions, reducing internal stress, and facilitating the control of wall thickness accuracy at the same time.

[0051] In addition, the directional arrangement of materials in the centrifugal field can optimize the microstructure of PTFE, enhance the comprehensive mechanical properties and airtightness of the products, especially the surface density which is crucial for improving the corrosion resistance. Centrifugal molding also makes the mold filling more thorough, reduces pores and interface defects, provides an ideal basis for subsequent surface treatment, and can be organically combined with surface coating technology to achieve process integration, significantly improving production efficiency, reducing energy consumption and environmental burden. Therefore, the adoption of the centrifugal molding process is an innovative technical path for preparing high-performance PTFE anti-corrosion plastic products, which is of great significance for solving problems such as poor material uniformity, high process energy consumption, and low production efficiency in the existing technology.

[0052] Preferably, a threaded sleeve is sleeved on the lead screw in the lead screw pair 21, and a through hole for accommodating the threaded sleeve is provided at the center below the support table 22, and the two are fixedly connected by bolts. Two through holes for cooperating with the two cylindrical guide rails of the lead screw pair 21 are provided on both sides below the support table. Therefore, the lead screw pair 21 makes the support table 22 perform stable axial movement through the rotation of the lead screw.

[0053] Preferably, two symmetrically distributed slide rails 32 are fixed on the surface of the support table 22, that is, at the upper end position of the lead screw pair 21, and the other ends of the slide rails 32 are fixed with push rods 31.

[0054] Preferably, the push rod 31 is fixed on a plate member, and the slide rail 32 is fixedly connected to the plate member, and the execution end of the push rod 31 passes through the plate member.

[0055] As an alternative embodiment, the push rod 31 can be a hydraulic push rod.

[0056] As an alternative embodiment, the push rod 31 can be an electric push rod.

[0057] Preferably, guide blocks 33 are sleeved on the outer walls of the two slide rails 32, and the motor 34 is fixed on the side facing the push rod 31, and the shaft end passes through the guide block 33. Therefore, the guide block 33 can drive the motor 34 to axially move on the slide rail 32. In addition, the tail of the motor 34 is fixedly connected to the execution end of the push rod 31.

[0058] Preferably, a fixed bracket is also fixed on the side of the motor 34 on the guide block 33, and the fixed bracket is fixedly connected to the execution end of the push rod 31. Therefore, when the push rod 31 expands and contracts, it can drive the motor 34 to axially move.

[0059] It should be noted that the lead screw pair 21 can drag the support table 22 and the driving unit 3 as a whole to axially move.

[0060] Preferably, the injection mold shell 111 is in the shape of a long cylinder, and an installation disk 1111 is fixed on the outer wall of one end thereof. The injection mold shell 111 is fixed on one side of the support table 22 and faces away from the motor 34. Specifically, the installation disk 1111 is fixedly connected to the surface of the support table 22 by bolts, and the end of the injection mold shell 111 with the installation disk 1111 penetrates through the inside of the support table 22. On the other side of the support table 22, an end cover 141 is fixed. A material gathering cavity 1411 is formed inside the end cover 141. Both sides of the material gathering cavity 1411 are through, and one side thereof is communicated with the inner cavity of the injection mold shell 111. A feed port penetrating to the outside is further formed on the inner wall of the material gathering cavity 1411, and the storage bin 142 is connected to the feed port through a pipeline.

[0061] Preferably, the storage bin 142 is used to store PTFE powder and modified PTFE, which are collectively referred to as PTFE raw materials in this application.

[0062] PTFE powder is usually a white fine granular substance, with characteristics of high viscosity, high crystallinity and low surface energy. Its particle size and morphology have a direct impact on the density and uniformity of the finally formed products. In the traditional PTFE powder centrifugal forming process, the powder usually needs to be preheated to reduce the friction between particles and improve its fluidity and uniform distribution ability in the centrifugal force field.

[0063] Modified PTFE improves the processing performance and specific functionality of PTFE by adding flow modifiers or functional fillers. Although this type of modification system improves the flow characteristics of PTFE, it still has significant non-Newtonian fluid behavior and high viscoelasticity.

[0064] It should be noted that the PTFE raw materials can enter the material gathering cavity 1411 through the storage bin 142.

[0065] As an alternative implementation, the storage bin 142 can be a storage tank for pre-storing PTFE raw materials. During the centrifugal forming process, the storage bin 142 can be continuously replaced to achieve the purpose of continuous feeding.

[0066] As an alternative implementation, the storage bin 142 can be a funnel-shaped open bin, and raw materials can be continuously injected into it from the outside.

[0067] Preferably, a screw rod 112 is sleeved inside the injection mold shell 111. One end of the screw rod 112 is immersed in the injection mold shell 111, and the other end passes through the injection mold shell 111 and the material gathering cavity 1411 until outside the end cover 141 and is fixedly connected to the motor 34. Specifically, the screw rod 112 is fixedly connected to the shaft end of the motor 34 through a coupling.

[0068] It should be noted that the local spiral guiding grooves on the rod body of the screw rod 112 are always inside the material gathering cavity 1411 during the entire centrifugal molding process to ensure the timely supply of PTFE raw materials.

[0069] Preferably, one end of the screw rod 112 inserted into the injection shell 111 is also fixed with an adjusting head 113. Specifically, the adjusting head 113 is conical with the conical tip facing outward. A round rod 1131 is fixed on the bottom surface of the adjusting head 113. A number of positioning blocks 1132 are arranged in an array and fixed on the outer wall of the round rod 1131. A number of through grooves 1133 are opened on the outer wall of the adjusting head 113 to increase the conveying space of the PTFE raw materials. The round rod 1131 is coaxial with the screw rod 112, inserted into the end of the screw rod 112, and fixedly connected by a bolt on the side.

[0070] It should be noted that only when the lead screw pair 21 works, the injection shell 111 can move axially; only when the motor 34 is driven, the screw rod 112 can be driven to rotate to ensure the continuous conveying of the PTFE raw materials in the injection shell 111. At this time, the positions of the injection shell 111 and the screw rod 112 will not change; only when the push rod 31 works, the motor 34 and the screw rod 112 can be driven to move axially synchronously. At this time, the positions of the injection shell 111 and the screw rod 112 change.

[0071] Preferably, a spring 114 and a siphon ring 115 are also sleeved on the round rod 1131 of the adjusting head 113. Specifically, the spring 114 and the siphon ring 115 are sleeved in sequence from the position of the adjusting head 113 to the positioning block 1132. The spring 114 acts on the siphon ring 115 and makes the siphon ring 115 abut against the positioning block 1132, and the outer wall of the siphon ring 115 fits with the inner wall of the injection shell 111.

[0072] It should be noted that an annular protrusion with a diameter larger than that of the round rod 1131 is provided at the connection between each positioning block 1132 and the round rod 1131, and the inner wall of the siphon ring 115 fits with the outer wall of the annular protrusion, ensuring that the PTFE raw materials can pass through the gap between the inner wall of the siphon ring 115 and the outer wall of the round rod 1131, and at the same time ensuring that the siphon ring 115 also has the effect of blocking the inner cavity of the injection shell 111.

[0073] Specifically, when the PTFE raw material is conveyed to the position of the siphon ring 115, the siphon ring 115 deflects against the action of the spring 114. At this time, a gap is formed between the inner wall of the siphon ring 115 and the round rod 1131. When the PTFE raw material is no longer conveyed, specifically modified PTFE, since the modified PTFE still exhibits non-Newtonian fluid behavior, under the slow action of the spring 114, the siphon ring 115 is pushed to the aforementioned annular protrusion. At this time, the inner cavity of the injection shell 111 is closed. At this time, the push rod 31 drags the screw rod 112 to axially move towards the motor 34. Since the siphon ring 115 blocks the inner cavity of the injection shell 111, the modified PTFE raw material inside the injection nozzle 116 can be driven by the siphon ring 115 for a short-distance backflow, or the overflow of the modified PTFE can be prevented.

[0074] Preferably, an injection nozzle 116 is further fixed to the outer end of the injection shell 111. The injection nozzle 116 has a cylindrical and two-way through inner cavity. Specifically, the injection nozzle 116 is fixed to the end of the injection shell 111 in a threaded connection form. A tapered opening 1161 is provided at the opening of the injection nozzle 116 facing the adjusting head 113. When the screw rod 112 axially moves, the adjusting head 113 axially moves accordingly. Therefore, the distance between the adjusting head 113 and the tapered opening 1161 can be adjusted to control the discharge amount of the PTFE raw material.

[0075] It should be noted that the modified PTFE in the injection shell 111 needs to maintain a constant pressure. Although the modified PTFE improves the processing performance by adding flow aids, its melt still has significant non-Newtonian fluid characteristics and high viscoelasticity. Pressure fluctuations will cause abnormal material flow behavior, resulting in uneven cross-sectional density, wall thickness fluctuations, and unstable displacement. In addition, separation or migration phenomena are likely to occur in a variable pressure environment. A constant pressure environment is a necessary condition for maintaining the uniform distribution of additives.

[0076] It should be noted that the traditional method of controlling the discharge amount of the PTFE raw material is to control the rotation speed of the screw rod 112. When the screw rod 112 conveys the modified PTFE, under the condition of internal constant pressure, the influence of the rotation speed of the screw rod 112 on the modified PTFE needs to be considered. In the low rotation speed region, the displacement is approximately linearly related to the rotation speed; in the medium rotation speed region, the growth rate of the displacement decreases; in the high rotation speed region, due to shear thinning and elastic effects, the growth of the displacement tends to saturate or even decrease, the filler may be oriented or separated, and the modified PTFE undergoes a viscosity mutation.

[0077] Therefore, by precisely controlling the axial distance between the end of the screw rod 112 and the injection nozzle 116, precise adjustment of the cross-sectional area of the discharge channel can be achieved, thereby achieving high-precision control of the discharge rate of modified PTFE. This adjustment method has a rapid response and precise control, and is particularly suitable for fine adjustment under fixed equipment parameters. In addition, there is a compensation relationship among the variables under constant pressure conditions. When the cross-sectional area increases, the rotational speed needs to be reduced, and the temperature can be appropriately reduced at this time.

[0078] Considering the influence of temperature change on the viscosity of modified PTFE, the compensation relationship at this time should be satisfied. When the temperature rises, the viscosity of modified PTFE decreases, and at this time, the cross-sectional area needs to be reduced or the rotational speed needs to be reduced.

[0079] Preferably, a plurality of heating coils 121 are fixed on both the outer wall of the injection nozzle 116 and the injection shell 111. The distribution spacing and quantity of the heating coils 121 are related to the power of the heating coils 121 and the length of the injection shell 111, and are respectively used for heating the injection nozzle 116 and gradient heating or stable heating of the injection shell 111. A heat preservation shell 122 is also sleeved on the outer wall of the heating coils 121 on the injection shell 111. Specifically, the inner wall of the heat preservation shell 122 fits with the outer walls of the heating coils 121 and the injection shell 111.

[0080] For PTFE powder, a progressive temperature gradient can be created through the heating coils 121, which can avoid uneven local melting caused by the sudden change temperature of PTFE powder, while the heat preservation shell 122 can eliminate the influence of external cold spots and prevent the powder from forming an uneven layered structure on the injection pipe wall.

[0081] For modified PTFE, the heating coils 121 can achieve a temperature gradient to prevent segregation or orientation of the filler during the flow process, while the heat preservation shell 122 can ensure a much finer multi-stage temperature control to ensure clear boundaries of each temperature zone.

[0082] Preferably, a mounting ring 131 is fixed at a position adjacent to the injection nozzle 116. Specifically, the mounting ring 131 is sleeved and fixed on the outer wall of the outer end of the injection shell 111, and at least three atomizing nozzles 132 distributed in a circle are also fixed on the side wall of the mounting ring 131.

[0083] As an alternative embodiment, the atomizing nozzle 132 adopts a double-head atomizing nozzle, which can reduce the quantity of the atomizing nozzles 132 and greatly ensure the spraying coverage range at the same time.

[0084] Preferably, the flow guide shell 133 is fixed to one side of the mounting plate 1111 and is fixed in the form of screw connection in this application. On the end face of the flow guide shell 133, the first gas injection nozzles 1331 and the first liquid injection nozzles 1333 with the same quantity as the atomizing nozzles 132 are fixed. The atomization of the atomizing nozzles 132 requires the synchronous input of high-pressure air and liquid medium to achieve the atomization effect of the liquid medium. In this application, each atomizing nozzle 132 is fixedly connected to the first gas injection nozzle 1331 and the first liquid injection nozzle 1333 through the first delivery pipe 135 and the second delivery pipe 136 respectively, and each forms a transportation channel. In addition, the first air extraction nozzle 1332 is also fixed on the end face of the flow guide shell 133 for vacuum pumping in subsequent processes.

[0085] Each of the first gas injection nozzles 1331, the first air extraction nozzles 1332 and the first liquid injection nozzles 1333 is respectively connected with a one-way channel 1338 opened inside the flow guide shell 133, and the one-way channels 1338 are not connected to each other. At different positions inside the flow guide shell 133, three non-connected confluence channels 1337 are opened. Each confluence channel 1337 is respectively connected with all the first gas injection nozzles 1331 or the first air extraction nozzles 1332 or the first liquid injection nozzles 1333 through the one-way channels 1338, that is, each confluence channel 1337 only plays a single role, such as gas injection, air extraction and liquid medium transportation.

[0086] In addition, at least one second gas injection nozzle 1334, second air extraction nozzle 1335 and second liquid injection nozzle 1336 are respectively fixed on the side wall of the flow guide shell 133. The second gas injection nozzle 1334, several second air extraction nozzles 1335 and several second liquid injection nozzles 1336 are also respectively connected with a one-way channel 1338 opened inside the flow guide shell 133, and the one-way channels 1338 are not connected to each other. At the same time, the second gas injection nozzle 1334, the second air extraction nozzle 1335 and the second liquid injection nozzle 1336 are respectively connected with the confluence channels 1337 through the one-way channels 1338, that is, the second gas injection nozzle 1334 is connected with multiple first gas injection nozzles 1331, and the same is true for the second air extraction nozzle 1335 and the second liquid injection nozzle 1336.

[0087] It should be noted that the second gas injection nozzle 1334 is connected with an air compressor, the second air extraction nozzle 1335 is connected with a vacuum pump, and the second liquid injection nozzle 1336 is connected with a spraying liquid supply device.

[0088] It should be noted that the types and purposes of the spraying liquid used in different centrifugal forming processes are different. For the PTFE powder centrifugal forming process, the spraying liquid should be a fluoride-based coating or a modified silicone coating, which can enhance the wettability and adhesion of the inner surface of PTFE, facilitate subsequent assembly, and provide special functions such as antistatic and conductive while maintaining the basic properties of PTFE. At the same time, it seals the fine pores formed during the PTFE sintering process, improves the airtightness of the product, and also provides a uniform and smooth inner surface to reduce the resistance when fluid passes through. For the modified PTFE centrifugal forming process, an epoxy-fluororesin composite system or a functionalized polyester coating is used, which can compensate for the uneven distribution of modifiers on the surface of modified PTFE, seal the surface defects that may be generated due to the introduction of flow aids, and provide a chemical barrier with the external environment to prevent the migration of modifiers.

[0089] Preferably, a sealing shell 134 is further fixed on the outer wall of the diversion shell 133. The sealing shell 134 is determined according to the length of the mold 4 and can closely cooperate with the sealing port 41 of the mold 4 to prevent the sealing shell 134 from not reaching the sealing port 41 due to the too short mold 4, resulting in the inability to perform the vacuum pumping operation.

[0090] It should be noted that when the inside of the mold 4 is evacuated during the forming stage and PTFE powder is used, the air between the powder particles can be removed, preventing the formation of micropores in the finished product. With the cooperation of centrifugal force, a higher material density can be obtained, and the internal stress can also be reduced, lowering the risk of subsequent deformation. When modified PTFE is used, the microbubbles at the matrix interface can be removed, the carbon-based and metal-based fillers can be protected from high-temperature oxidation, the tight combination between the fillers and the matrix can be enhanced, and the volatile substances that may be generated by the filler treatment agent or interface agent can be removed at the same time. Embodiment

[0091] Refer to Figure 7 , which is the second embodiment of the present invention. This embodiment provides a method for forming a polytetrafluoroethylene anti-corrosion plastic, which uses a centrifugal forming process and includes a mold 4, a sealing port 41 opened on one side of the mold 4, and a transmission shaft 42 fixed on the other end face of the mold 4.

[0092] It should be noted that the mold 4 needs to be connected to a driving source, such as a motor, and fixedly connected to the transmission shaft 42 to ensure the rotational centrifugal effect of the mold 4.

[0093] It should be noted that during the centrifugal forming process, the raw materials are first transported to the feeding assembly 11 through the precise metering system of the screw rod 112, and the pressure fluctuation caused by the pressure fluctuation is avoided through constant pressure control. Subsequently, the discharge amount is precisely controlled through the adjustable spacing adjustment head 113, and then the materials are injected into the rotating mold 4. Under the action of the centrifugal force field, the materials are evenly distributed on the inner wall of the mold 4 and form an initial shape.

[0094] During the centrifugation process, the initial structure of PTFE powder is mainly formed by mechanical interlocking between particles. For modified PTFE, under the action of the centrifugal force field, fillers or modifiers can obtain a more uniform spatial distribution.

[0095] Compared with traditional pressure molding, centrifugal molding uses the centrifugal force field to provide a directional compaction force that matches the geometry of the mold, effectively solving the problems of uneven axial distribution and wall thickness fluctuation. At the same time, it improves the density uniformity and surface quality of PTFE products, laying a foundation for subsequent anti-corrosion treatment. Especially for tubular anti-corrosion products, by adopting the method of controlling the axial movement of the injection unit 1 in the mold 4 with the lead screw pair 21 and combining the action of centrifugal force, double uniform distribution of materials in the axial and radial directions can be achieved, significantly improving the product performance.

[0096] Specifically, when using the PTFE powder centrifugal molding process, the PTFE powder needs to be fed into the material gathering cavity 1411 through the storage bin 142. The material gathering cavity 1411 needs to ensure continuous and stable powder supply without interruption. Before the powder enters, it should be preheated to an appropriate temperature to reduce the friction between particles.

[0097] Subsequently, the motor 34 rotates at a constant speed and drives the screw rod 112 to operate. The spiral guide groove on the screw rod 112 is continuously located inside the material gathering cavity 1411 to ensure continuous transportation of PTFE powder. The regulating head 113 needs to cooperate with the distance between the conical opening 1161 of the injection nozzle 116 to control the discharge volume. When the powder passes through the siphon ring 115, the spring 114 is compressed. At the same time, the heating coil 121 conducts gradient heating on the injection shell 111 to construct a progressive temperature gradient. The heat preservation shell 122 sleeved outside the heating coil 121 is used to eliminate the influence of external cold spots and stabilize the temperature to avoid local uneven melting caused by sudden temperature changes of PTFE powder.

[0098] Then the lead screw pair 21 rotates, driving the support platform 22 and the entire injection unit 1 to move axially. At the same time, powder is continuously and stably injected into the mold 4, ensuring uniform distribution of the powder inside the mold 4. Subsequently, the injection nozzle 116 is aligned with the sealing port 41 of the mold 4 and precise positioning is achieved. When the sealing shell 134 is tightly fitted with the sealing port 41 of the mold 4 to form a seal, the injection of powder is stopped.

[0099] Subsequently, the mold 4 rotates at a high speed and constantly, generating a stable centrifugal force field. The PTFE powder is uniformly distributed on the inner wall of the mold under the action of the centrifugal force. Since the second air extraction nozzle 1335 is connected to a vacuum pump, an air extraction channel is formed through the confluence channel 1337, the one-way channel 1338 and the first air extraction nozzle 1332 to continuously evacuate the inside of the mold 4, removing the air between the powder particles, ensuring sintering in a vacuum environment, avoiding oxidation, and improving the product density.

[0100] The temperature of the mold 4 needs to be maintained in the range of 340 - 380 °C. At high temperatures, the interfaces between PTFE powder particles melt to form an integral structure. After that, an appropriate sintering time is maintained to ensure the full crystallization of PTFE and the stability of the structure.

[0101] Next, the push rod 31 drives the motor 34 and the screw rod 112 to move axially in the reverse direction, the injection nozzle 116 gradually withdraws, and the second air inlet nozzle 1334 and the second liquid injection nozzle 1336 supply compressed air and fluoride-based coating to the atomizing nozzle 132 through the confluence channel 1337 and the one-way channel 1338. Specifically, the atomizing nozzle 132 atomizes and sprays the coating onto the inner surface of the product through the first delivery pipe 135 and the second delivery pipe 136. At this time, the surface coating fills the micro pores, which can improve the airtightness of the product.

[0102] Finally, the temperature of the mold decreases at an appropriate rate to avoid deformation caused by thermal stress. After reaching the demolding temperature, the mold is opened and the finished product is taken out. After post-treatment inspection, the finished product completes the manufacturing process.

[0103] When using the modified PTFE centrifugal forming process, the surface-treated modified PTFE is transported from the storage bin 142 to the aggregating cavity 1411 to ensure that the filler and the PTFE matrix are pre-mixed evenly without separation. If the raw material has an appropriate loose packing density, the stability of subsequent processing can be guaranteed.

[0104] Subsequently, the motor 34 drives the screw rod 112 at a speed lower than that of the PTFE powder process to ensure that the low-shear force transportation reduces the oriented arrangement of the filler during the flow process. Then, the distance between the adjusting head 113 and the conical opening 1161 of the injection nozzle 116 is precisely controlled, and a constant pressure is maintained to prevent the separation or migration of the filler.

[0105] At the same time, the heating coil 121 needs to perform multi-stage precise temperature control to form a clear temperature gradient, and the heat preservation shell 122 is used to ensure that the boundaries of each temperature zone are clear to prevent the segregation of the filler. The temperatures in the feeding area, the middle section, and the discharging area need to be precisely controlled within specific ranges respectively.

[0106] Subsequently, the lead screw pair 21 drives the injection unit 1 to move axially more precisely, so that the injection nozzle 116 is precisely aligned with the mold 4. During this process, the modified PTFE is evenly and continuously injected into the inner wall of the mold 4. Due to the high viscosity of the modified PTFE, it is necessary for the modified PTFE to be continuously distributed in the axial direction of the mold 4 until the sealing shell 134 arrives and forms a high-vacuum sealing interface with the sealing port 41 of the mold 4. At this time, the discharge of the modified PTFE is interrupted, and the siphon ring 115 will control the reflux of the modified PTFE under the action of the spring 114 and prevent overflow.

[0107] Subsequently, the mold 4 rotates at a lower speed first to ensure the initial uniform distribution of the modified PTFE, and then the rotation speed is increased to increase the centrifugal force to achieve material densification. At the same time, intermittent pulsed short-term acceleration is added to prevent the settlement of high-density fillers.

[0108] Next, an efficient vacuum pumping system is formed through the second air extraction nozzle 1335, the confluence channel 1337, the one-way channel 1338, and the first air extraction nozzle 1332. Specifically, at the initial stage of molding, short-term strong vacuum pumping is carried out to remove most of the gas, and at the middle stage of sintering, long-term slow vacuum pumping is carried out to treat the microbubbles at the interface between the filler and the matrix.

[0109] During the sintering process, the temperature of the mold adopts a stepped heating strategy, which is controlled in multiple temperature intervals, and each temperature interval is maintained for a specific time to ensure sufficient bonding at the interface between the filler and the matrix. In particular, the time control in the high-temperature section needs to be more precise to avoid deterioration of the interface between the filler and the matrix.

[0110] After that, the push rod 31 controls the axial reverse movement of the screw rod 112, and the injection nozzle 116 withdraws. At the same time, the epoxy-fluororesin composite system coating is conveyed through the second liquid delivery nozzle 1336. The atomizing nozzle 132 atomizes the coating after receiving the compressed air and the coating conveyed by the first delivery pipe 135 and the second delivery pipe 136 to achieve uniform spraying. It should be noted that coating at a lower temperature can compensate for the uneven distribution of the modifier.

[0111] Finally, in the demolding stage, the cooling rate needs to be strictly controlled to prevent microcracks caused by thermal stress, and an appropriate vacuum degree is maintained during the cooling process to avoid the formation of secondary bubbles. When the demolding temperature is reached, the finished product is taken out for surface quality and filler distribution detection.

[0112] In summary, the present application can be applied to both the centrifugal molding process of PTFE powder and modified PTFE, and different process requirements can be achieved through the same basic device. Both processes convey raw materials from the storage bin 142, measure and convey them through the screw rod 112, and use the centrifugal force generated by the rotation of the mold to achieve uniform distribution of the materials. Finally, they are sintered and formed in a vacuum environment and subjected to surface spraying treatment, but there are significant differences in specific control. The PTFE powder process uses uniform high-speed rotation for conveying, constant centrifugal speed, and single-temperature zone control, while the modified PTFE process implements low-speed conveying to reduce filler shear orientation, uses a variable centrifugal curve to prevent filler settlement, and also conducts multi-stage fine temperature control and stepped sintering. Both processes can achieve improved material distribution uniformity, precise displacement control, and process integration, but the modified PTFE process pays more attention to improving filler distribution, optimizing interface bonding, and managing thermal stress, effectively solving the problems of uneven material distribution and poor interface bonding in traditional PTFE processing, and providing technical support for the preparation of high-performance PTFE anti-corrosion products.

[0113] Compared with traditional forming processes, such as the free extrusion process which is cumbersome and has a heavy environmental burden, the casting film technology which is inefficient and has uneven wall thickness, and the isostatic pressing forming which has high equipment requirements and limited geometric shapes, the present application adopts a centrifugal forming process. It can adjust the discharge of raw materials through dynamic spacing, distribute them evenly in the axial direction within the mold, eliminate bubbles through a vacuum environment to increase density, and at the same time integrate the forming and surface spraying processes, achieving a shortened process chain and reduced environmental burden.

[0114] In particular, aiming at the problem that the low surface energy of PTFE makes it difficult for coatings to adhere, the present application sprays coatings under a vacuum environment, significantly improving the surface treatment effect and providing a complete solution for the efficient preparation of high-performance PTFE and modified PTFE anti-corrosion products.

[0115] Importantly, the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit them. Although the present invention has been described in detail with reference to the preferred embodiments, those of ordinary skill in the art should understand that the technical solutions of the present invention can be modified or equivalently replaced without departing from the spirit and scope of the technical solutions of the present invention, and they should all be covered within the scope of the claims of the present invention.

Claims

1. A polytetrafluoroethylene anti-corrosion plastic molding device, characterized in that: including, an injection molding unit (1), comprising a feeding component (11), a plurality of heat preservation components (12) sleeved on the outer wall of the feeding component (11), an auxiliary component (13) sleeved on the outer wall of the heat preservation component (12), and a feeding component (14) fixed at one end of the feeding component (11); the feeding component (11) includes an injection molding shell (111), a screw rod (112) sleeved on the inner wall of the injection molding shell (111), an adjusting head (113) fixed at the end of the screw rod (112), a spring (114) and a siphon ring (115) respectively sleeved on the outer wall of the adjusting head (113), and an injection nozzle (116) fixed at the end of the injection molding shell (111); the injection molding shell (111) is cylindrical and includes a mounting disc (1111) fixed on its outer wall; the auxiliary component (13) includes a mounting ring (131) fixed on one side of the injection nozzle (116), an atomizing nozzle (132) fixed on the outer wall of the mounting ring (131), a diversion shell (133) fixed on the mounting disc (1111), a sealing shell (134) fixed on the diversion shell (133), and a first delivery pipe (135) and a second delivery pipe (136) communicated with the atomizing nozzle (132); the diversion shell (133) includes a first gas injection nozzle (1331), a first air extraction nozzle (1332) and a first liquid injection nozzle (1333) opened on its outer wall, a plurality of second gas injection nozzles (1334), a plurality of second air extraction nozzles (1335) and a plurality of second liquid injection nozzles (1336) arranged on one side of the diversion shell (133), and a plurality of confluence channels (1337) and a plurality of one-way channels (1338) opened inside the diversion shell (133); the molding device further includes a mold (4), a sealing port (41) opened on one side of the mold (4), and a transmission shaft (42) fixed on the other end face of the mold (4).

2. The polytetrafluoroethylene anti-corrosion plastic molding device according to claim 1, characterized in that: the molding device further includes a moving unit (2), comprising a lead screw pair (21), and a support table (22) fixed on the outer wall of the threaded sleeve of the lead screw pair (21); a driving unit (3), comprising a push rod (31) arranged on one side of the support table (22), a slide rail (32) fixed between the support table (22) and the push rod (31), a guide block (33) sleeved on the outer wall of the slide rail (32), and a motor (34) penetrating through one side of the guide block (33); the other end of the injection molding shell (111) is fixedly connected to the surface of the support table (22), and the screw rod (112) penetrates through the center of the support table (22) and is fixedly connected to the shaft end of the motor (34).

3. The polytetrafluoroethylene anti-corrosion plastic molding device according to claim 2, characterized in that: The adjusting head (113) is conical and includes a round rod (1131) fixed to one side thereof, a positioning block (1132) fixed to the outer wall of the round rod (1131), and a through groove (1133) formed in the outer wall of the adjusting head (113); The injection nozzle (116) is cylindrical and includes a tapered opening (1161) formed at one end thereof.

4. The polytetrafluoroethylene anti-corrosion plastic molding device according to claim 3, wherein: The feeding assembly (14) includes an end cap (141) and a storage bin (142) fixed to the side wall of the end cap (141); The end cap (141) includes a material gathering cavity (1411) provided therein; the storage bin (142) communicates with the material gathering cavity (1411).

5. The polytetrafluoroethylene anti-corrosion plastic molding device according to claim 4, wherein: The heat preservation assembly (12) includes a heating coil (121) sleeved on the outer walls of the injection nozzle (116) and the injection shell (111) respectively, and a heat preservation shell (122) sleeved on the outside of the heating coil (121).

6. The polytetrafluoroethylene anti-corrosion plastic molding device according to claim 5, wherein: The first inflation nozzle (1331), the first air extraction nozzle (1332), the first liquid injection nozzle (1333), the second inflation nozzle (1334), the second air extraction nozzle (1335) and the second liquid injection nozzle (1336) are respectively connected with one-way channels (1338); The first inflation nozzle (1331) communicates with each of the second inflation nozzles (1334) through one of the confluence channels (1337); The first air extraction nozzle (1332) communicates with each of the second air extraction nozzles (1335) through one of the confluence channels (1337); The first liquid injection nozzle (1333) communicates with each of the second liquid injection nozzles (1336) through one of the confluence channels (1337).

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