Manufacturing process of fluorine-lined ball valve ball

Abstract

The application discloses a kind of fluorine lining ball valve valve ball manufacturing process, comprising the following steps: filling, setting mould assembly is filled with mould assembly, mould assembly is equipped with mould cavity and with it Communication feeding channel, exhaust hole, exhaust hole inner wall is coated with silicone insulating paint layer, metal body is loaded into mould cavity and closes mould, fluorine material is added into feeding channel and closes feeding channel;Heating sintering, mould assembly is placed into sintering furnace and heated to preset temperature T and keeps preset time t1, so that fluorine material is melted into fluid;Die pressing solidification, mould assembly is taken out from furnace, and it is applied to it with press machine preset pressure F and keeps preset time t2, so that fluorine material flows and is fully coated and bonded to metal body, bubble and excess fluorine material are discharged through exhaust hole, and fluorine plastic layer is formed after fluorine material coated on metal body is cooled and solidified;Finished product demolding, opening mould takes out the valve ball prepared by the above process, can reduce the possibility of bubble between metal body and fluorine plastic layer, and obtain better finished product quality.

Description

Technical Field

[0001] This invention relates to the field of valve body manufacturing technology, and in particular to a valve ball manufacturing process for a fluoropolymer-lined ball valve. Background Technology

[0002] A PTFE-lined ball valve is a type of ball valve. Compared to ordinary ball valves, the valve cavity and ball of a PTFE-lined ball valve are covered with a layer of fluoroplastic (PTFE), thus having excellent corrosion resistance. In contrast, the valve body and core of ordinary ball valves are generally made of metal materials such as stainless steel and copper alloys, which have poor corrosion resistance to some highly corrosive media.

[0003] For fluoropolymer-lined ball valves, the ball lining is typically achieved through compression molding. During manufacturing, a metal body is placed into a mold, followed by the addition of fluoropolymer material and sintering. This allows the fluoropolymer to melt and flow, coating the metal body. Pressure is applied to force the material to flow, fully fill, and adhere to the metal body, thus forming a fluoropolymer layer on the metal surface, achieving the fluoropolymer lining of the valve ball. However, existing fluoropolymer lining methods often result in air bubbles between the metal body and the fluoropolymer layer, leading to inconsistent thickness of the fluoropolymer layer. Some areas of the fluoropolymer layer become thinner, making them prone to cracking and defects during subsequent processing. Therefore, the process needs improvement. Summary of the Invention

[0004] This invention aims to at least solve one of the technical problems existing in the prior art. To this end, this invention proposes a manufacturing process for the valve ball of a fluoropolymer-lined ball valve, which can reduce the possibility of air bubbles forming between the metal body and the fluoropolymer layer, and facilitates achieving the required thickness of the fluoropolymer layer, resulting in better finished product quality.

[0005] According to the embodiment of the present invention, the manufacturing process of the fluoropolymer-lined ball valve includes a valve ball comprising a metal body and a fluoropolymer layer covering the metal body. The manufacturing process includes the following steps:

[0006] The mold is filled with filling material and a mold assembly is set up. The mold assembly is provided with a mold cavity, a feeding channel and a venting hole. The feeding channel and the venting hole are both connected to the mold cavity. An organosilicon insulating varnish layer is coated on the inner wall of the venting hole. The metal body is put into the mold cavity and the mold is closed and locked. Granular fluorine material is added to the feeding channel and the inlet of the feeding channel is closed.

[0007] Heating and sintering: The mold assembly is placed in a sintering furnace and heated to a preset temperature T and held for a preset time t1, so that the granular fluorine material melts into a fluid.

[0008] Compression molding and curing: The mold assembly is taken out of the sintering furnace, and a preset pressure F is applied to the mold assembly using a press and held for a preset time t2, so that the fluid fluorine material flows and fully coats and adheres to the metal body. The air bubbles formed in the fluorine material and the excess fluorine material are discharged through the vent hole. After the fluorine material coated on the metal body cools and solidifies, it forms the fluoroplastic layer.

[0009] The finished product is demolded by opening the mold assembly and removing the valve ball from the mold cavity.

[0010] The valve ball manufacturing process of the fluoropolymer-lined ball valve according to the embodiments of the present invention has at least the following beneficial effects: by setting vent holes in the mold assembly and coating the inner wall of the vent holes with an organosilicon insulating varnish layer, during the compression molding and curing step, the air bubbles formed in the fluoropolymer and the excess fluoropolymer are discharged through the vent holes. Furthermore, the organosilicon insulating varnish layer forms a smooth protective film after heating and curing, which increases the smoothness of the inner wall of the vent holes and isolates the corrosive substances generated during the heating of the fluoropolymer from direct contact with the inner wall of the vent holes. This prevents the corrosive substances from corroding the inner wall of the vent holes and generating oxides, thereby improving the fluid flow in the vent holes. This facilitates the smooth discharge of air bubbles and excess fluoropolymer, reduces the possibility of air bubbles between the metal body and the fluoropolymer layer, helps to ensure that the thickness of the fluoropolymer layer meets the requirements, reduces the possibility of cracking of the fluoropolymer layer during subsequent processing, improves the finished quality of the valve ball, and facilitates production and application.

[0011] According to some embodiments of the present invention, the surface of the metal body and the inner wall of the mold cavity are cleaned before the molding and filling step.

[0012] According to some embodiments of the present invention, the valve ball is provided with a through valve core channel, the mold assembly includes an upper mold base, a lower mold base, a mandrel and a push rod, the upper mold base and the lower mold base enclose the mold cavity, the feeding channel is provided on the upper mold base, the push rod is adapted to the feeding channel, the mandrel is adapted to the valve core channel, the mandrel is provided with a discharge channel, and the vent is provided on the mandrel and communicates with the discharge channel; during the molding and filling step, the mandrel is inserted into the metal body and a gap is formed between the mandrel and the metal body for the fluorine material to flow in, and the push rod is inserted into the feeding channel to block and close the entrance of the feeding channel; during the pressing and curing step, the press applies a preset pressure F to the push rod, so that the push rod extrudes the fluid fluorine material to fill the mold cavity and coat and bond it to the metal body.

[0013] According to some embodiments of the present invention, the number of exhaust holes is no more than three.

[0014] According to some embodiments of the present invention, the diameter of the vent hole ranges from 1.5 mm to 2.5 mm.

[0015] According to some embodiments of the present invention, in the heating and sintering step, the preset temperature T ranges from 340°C to 350°C.

[0016] According to some embodiments of the present invention, in the heating and sintering step, the preset time t1 ranges from 4h to 11h.

[0017] According to some embodiments of the present invention, in the molding and curing step, the preset pressure F ranges from 1 MPa to 5.5 MPa.

[0018] According to some embodiments of the present invention, in the molding and curing step, the preset time t2 ranges from 10 min to 35 min.

[0019] According to some embodiments of the present invention, in the molding and curing step, after the press applies a preset pressure F to the mold assembly and maintains it for a preset time t2, the pressure applied by the press to the mold assembly is gradually reduced while the mold assembly is cooled.

[0020] Additional aspects and advantages of the invention will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. Attached Figure Description

[0021] The above and / or additional aspects and advantages of the present invention will become apparent and readily understood from the description of the embodiments taken in conjunction with the following drawings, in which:

[0022] Figure 1 This is an exploded view of the mating structure of the mold assembly and the metal body in an embodiment of the present invention;

[0023] Figure 2 This is a schematic diagram of the valve ball in an embodiment of the present invention.

[0024] Figure label:

[0025] Valve ball 100, valve core channel 101, metal body 110, fluoroplastic layer 120;

[0026] Mold assembly 200, mold cavity 201, feeding channel 202, vent hole 203, discharge channel 204, upper mold base 210, lower mold base 220, support column 221, mandrel 230, push rod 240. Detailed Implementation

[0027] Embodiments of the present invention are described in detail below. Examples of these embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present invention, and should not be construed as limiting the present invention.

[0028] In the description of this invention, if words such as several, greater than, less than, exceeding, above, below, or within appear, then several means one or more, multiple means two or more, greater than, less than, exceeding, etc. are understood to exclude the number itself, and above, below, or within are understood to include the number itself.

[0029] In the description of this invention, unless otherwise explicitly defined, terms such as "set up," "install," and "connect" should be interpreted broadly, and those skilled in the art can reasonably determine the specific meaning of the above terms in this invention in conjunction with the specific content of the technical solution.

[0030] In the existing fluoropolymer lining process for valve balls, when the fluoropolymer is loaded into the mold and heated for sintering, due to the highly decomposable nature of the fluoropolymer, small molecules are released during the heating process due to chemical reactions such as condensation. These small molecules expand in volume at high temperatures, forming bubbles. These bubbles are difficult to remove from the mold and thus flow with the molten fluoropolymer to coat the metal body 110. This results in a bubble structure or even delamination between the metal body 110 and the fluoropolymer layer 120. The presence of these bubbles reduces the thickness of the fluoropolymer layer 120, making it thinner and more prone to cracking and defects during subsequent processing. Therefore, the existing manufacturing process of the valve ball 100 needs to be improved.

[0031] Reference Figure 1 and Figure 2 A manufacturing process for a fluoropolymer-lined ball valve, wherein the ball 100 comprises a metal body 110 and a fluoropolymer layer 120 covering the metal body 110, and the manufacturing process includes the following steps:

[0032] The mold is filled with filling material and a mold assembly 200 is set up. The mold assembly 200 is provided with a mold cavity 201, a feeding channel 202 and a venting hole 203. The feeding channel 202 and the venting hole 203 are both connected to the mold cavity 201. An organosilicon insulating varnish layer is coated on the inner wall of the venting hole 203. The metal body 110 is put into the mold cavity 201 and the mold is closed and locked. The granular fluorine material is added into the feeding channel 202 and the inlet of the feeding channel 202 is closed.

[0033] Heating and sintering: The mold assembly 200 is placed in a sintering furnace and heated to a preset temperature T and held for a preset time t1, so that the granular fluorine material is melted into a fluid.

[0034] Compression molding and curing: The mold assembly 200 is taken out of the sintering furnace. A preset pressure F is applied to the mold assembly 200 using a press and held for a preset time t2, so that the fluid fluorine material flows and fully coats and adheres to the metal body 110. The air bubbles formed in the fluorine material and the excess fluorine material are discharged through the vent 203. After the fluorine material coated on the metal body 110 cools and solidifies, a fluoroplastic layer 120 is formed.

[0035] The finished product is demolded by opening the mold assembly 200 and removing the valve ball 100 from the mold cavity 201.

[0036] Understandably, when the fluorine material is loaded into the mold assembly 200 for heating and sintering, due to its highly decomposable nature, the fluorine material will release small molecules through chemical reactions such as condensation during heating. These small molecules expand in volume at high temperatures, forming bubbles. By providing vent holes 203 in the mold assembly 200, the bubbles formed in the fluorine material and excess fluorine material can be discharged through the vent holes 203 under the pressure of the press during the molding and curing step. Furthermore, since the inner wall of the vent hole 203 is coated with an organosilicon insulating varnish layer, this layer forms a smooth protective film after heating and curing, increasing the smoothness of the inner wall of the vent hole 203. Since the fluorine material has poor fluidity in the molten state, the smooth inner wall of the vent hole 203 facilitates the discharge of the fluorine material. On the other hand, the heating of the fluorine material will produce substances that are corrosive to the mold assembly 200 (which is generally made of ordinary carbon steel), easily corroding the inner wall of the vent hole 203 and forming oxygen. The addition of a silicone insulating varnish layer to the inner wall of the vent hole 203 increases the roughness of the inner wall, hindering the discharge of molten fluorine material and causing it to clog the vent hole 203. This prevents the generated bubbles from being discharged with the fluorine material. However, by coating the inner wall of the vent hole 203 with a silicone insulating varnish layer, the protective film formed can isolate the corrosive substances generated during the heating of the fluorine material from direct contact with the inner wall of the vent hole 203. This prevents the corrosive substances from corroding the inner wall of the vent hole 203 and generating oxides, thereby improving the fluidity of the molten fluorine material in the vent hole 203, reducing the possibility of fluorine material clogging the vent hole 203, and facilitating the smooth discharge of bubbles and excess fluorine material. This also reduces the possibility of bubbles appearing between the metal body 110 and the fluoroplastic layer 120, helps to ensure that the thickness of the fluoroplastic layer 120 meets the requirements, reduces the possibility of the fluoroplastic layer 120 cracking during subsequent processing, improves the quality of the valve ball 100, and facilitates production and application.

[0037] In practical applications, the fluorinated material can be polytetrafluoroethylene (PTFE), soluble polytetrafluoroethylene (PFA), or perfluoroethylene propylene (FEP), etc. In this embodiment, the fluorinated material is specifically tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer (PFA). Since the sintering furnace, press, etc. in this embodiment are all existing equipment, their specific composition is known to those skilled in the art, so they will not be described in detail here. The specific structure of the mold assembly 200 and the specific parameters used in the above steps will not be described in detail here, but will be explained in detail below.

[0038] In some embodiments, the surface of the metal body 110 and the inner wall of the mold cavity 201 are cleaned before the molding and filling step.

[0039] Understandably, before the molding and filling step, the surface of the metal body 110 and the inner wall of the mold cavity 201 can be wiped clean with a cleaning cloth dampened with detergent or gasoline to remove oil and other impurities, reducing the possibility of impurities in the subsequent fluoroplastic layer 120. In practical applications, the surface of the metal body 110 can also be cleaned using ultrasonic cleaning equipment; the specific cleaning method can be set according to actual usage needs.

[0040] In some embodiments, the valve ball 100 is provided with a through valve core channel 101, and the mold assembly 200 includes an upper mold base 210, a lower mold base 220, a mandrel 230, and a push rod 240. The upper mold base 210 and the lower mold base 220 enclose a mold cavity 201. A feeding channel 202 is provided on the upper mold base 210, the push rod 240 is adapted to the feeding channel 202, the mandrel 230 is adapted to the valve core channel 101, a discharge channel 204 is provided inside the mandrel 230, and an exhaust hole 203 is provided in the mandrel 230. The mandrel 230 is connected to the discharge channel 204. During the molding and filling step, the mandrel 230 is inserted into the metal body 110 and a gap is formed between the mandrel 230 and the metal body 110 for the fluorine material to flow in. The push rod 240 is inserted into the feeding channel 202 to block and close the entrance of the feeding channel 202. During the molding and curing step, the press applies a preset pressure F to the push rod 240, so that the push rod 240 extrudes the fluid fluorine material to fill the mold cavity 201 and coat and bond it to the metal body 110.

[0041] Understandably, such as Figure 1 and Figure 2As shown, the upper mold base 210 and the lower mold base 220 are closed to form a mold cavity 201. A feeding channel 202 is located in the upper mold base 210 and communicates with the mold cavity 201. The lower mold base 220 has a support column 221 within the mold cavity 201. A discharge channel 204 is located within the mandrel 230, and a vent 203 is located on the mandrel 230 and communicates with the discharge channel 204. During the mold filling step, when the metal body 110 is inserted into the mold cavity 201, the support column 221 supports the metal body 110. The metal body 110 is suspended relative to the inner wall of the mold cavity 201 to facilitate the subsequent coating of the metal body 110 with fluorine material. Multiple support columns 211 can be provided to better support the metal body 110. During the molding and filling step, the mandrel 230 is inserted into the metal body 110, forming a gap between it and the metal body 110 for fluorine material to flow in. The push rod 240 is inserted into the feeding channel 202 and its upper inlet is blocked. During the molding and curing step, the press presses the push rod 240... A preset pressure F is applied, pushing the push rod 240 to move along the feeding channel 202, causing the push rod 240 to expel the fluorine material into and fill the mold cavity 201. Simultaneously, the fluorine material coats and bonds to the metal body 110. Some fluorine material enters the gap outside the mandrel 230, forming the inner wall of the valve core channel 101. Under the pressure F, air bubbles are discharged from the vent hole 203 along with excess fluorine material to the discharge channel 204. During the demolding step after molding, after the mandrel 230 is pulled out, the insertion position of the mandrel 230 is... The valve core channel 101 of the valve ball 100 is in direct contact with the medium during actual use. Since the vent 203 and the discharge channel 204 are both located on the mandrel 230, it is beneficial for the air bubbles in the fluorine material on the inner wall of the valve core channel 101 to be discharged with the excess fluorine material. This ensures the molding quality of the fluorine plastic layer 120 on the inner wall of the valve core channel 101, better copes with the working conditions of direct contact with the medium, and helps to improve the service life of the valve ball 100.

[0042] In some embodiments, the support column 221 can move relative to the inner wall of the mold cavity 201 to support the metal body 110 or move away from the mold cavity 201. During the compression molding and curing step, the support column 221 first supports the metal body 110 and then moves away from the mold cavity 201. Specifically, during the filling process, the support column 221 moves to protrude relative to the inner wall of the mold cavity 201 to support the metal body 110, making the metal body 110 suspended relative to the inner wall of the mold cavity 201. Throughout the heating and sintering step and in the early stage of the compression molding and curing step, the support column 221 remains stationary, maintaining support for the metal body 110, allowing the molten fluorine material to flow and fill the gap between the outer surface of the metal body 110 and the inner wall of the mold cavity 201, covering the metal body 110. 1. After supporting the metal body 110 for a period of time during the molding and curing step, the molten fluorine material covering the outside has formed a support for the metal body 110. At this time, the support column 221 moves and retracts, leaving the mold cavity 201, releasing the support contact between the support column 221 and the metal body 110. The molten fluorine material can fill the gap in the original position of the support column 221 under the action of the preset pressure F, realizing the complete coating of the metal body 110 with fluorine material, avoiding the trouble of subsequent material replenishment, and achieving a better fluorine lining effect. In practical applications, the support column 221 can be a threaded part, which is threadedly connected to the lower mold base 220. By rotating the support column 221, the movement of the support column 221 can be realized. Alternatively, the support column 221 can be a telescopic rod, pin, etc. The support time of the support column 221 on the metal body 110 during the molding and curing step can be set according to the actual use needs.

[0043] In some embodiments, the metal body 110 is provided with a connecting hole (not shown in the figure). When the metal body 110 is installed into the mold cavity 201, the gap between the outer surface of the metal body 110 and the inner wall of the mold cavity 201 and the gap between the mandrel 230 and the metal body 110 can be connected through the connecting hole, so that the fluoroplastic layer 120 on the outer surface of the metal body 110 and the fluoroplastic layer 120 on the inner wall of the valve core channel 101 are connected together through the fluoroplastic in the connecting hole, which better fixes the position of the two, facilitates the bonding and fixing of the fluoroplastic layer 120 and the metal body 110, and achieves a better fluoropolymer lining effect.

[0044] In some embodiments, the number of vent holes 203 is no more than three. It is understood that, as Figure 1As shown, the mandrel 230 is provided with two vent holes 203. According to the experiment, the number of vent holes 203 should not exceed three. Too many vent holes 203 will not improve the bubble discharge result, and will also cause excessive discharge of fluorine material, resulting in material waste. Therefore, the number of vent holes 203 should be set to one to three according to the size of the valve ball 100. For example, there can be one or three vent holes 203, which can be set according to the actual use needs.

[0045] In some embodiments, the diameter of the vent hole 203 ranges from 1.5 mm to 2.5 mm. It is understood that by setting the diameter of the vent hole 203 within this range (inclusive), a suitable range is achieved. This helps prevent excessive discharge of fluorine material due to an excessively large diameter, resulting in material waste, or excessively small diameter, which could affect venting efficiency and create resistance, hindering demolding. In practical applications, the diameter of the vent hole 203 can be 1.5 mm, 2 mm, or 2.5 mm, depending on the specific application requirements.

[0046] In some embodiments, the preset temperature T in the heating and sintering step ranges from 340°C to 350°C. It is understood that by setting the preset temperature T between 340°C and 350°C (inclusive), the sintering temperature is kept within a suitable range. This helps to avoid the fluorine material becoming too fluid due to excessively low sintering temperatures, or the fluorine material decomposition products increasing due to excessively high sintering temperatures, thus affecting the quality of the finished product. In practical applications, the preset temperature T can be 340°C, 345°C, or 350°C, and can be set accordingly based on actual usage requirements.

[0047] In some embodiments, the preset time t1 in the heating sintering step ranges from 4 hours to 11 hours. It is understood that by setting the preset time t1 within the range of 4 to 11 hours (inclusive), the sintering time is kept within a suitable range. This helps avoid situations where the sintering time is too short, potentially resulting in insufficient temperature and affecting molding, or where the sintering time is too long, leading to an increase in decomposition products of the fluorine material and affecting the quality of the finished product. In practical applications, the preset time t1 can be 4 hours, 8 hours, or 11 hours, and can be set according to actual usage requirements.

[0048] In some embodiments, the preset pressure F in the molding and curing step ranges from 1 MPa to 5.5 MPa. It is understood that by setting the preset pressure F within the range of 1 MPa to 5.5 MPa (inclusive), the molding pressure is kept within a suitable range. This helps avoid defects such as insufficient molding pressure leading to loose molding and shrinkage of the fluorinated material, causing indentations, or excessive molding pressure causing deformation of the mold assembly 200 and metal body 110, and extrusion of the fluorinated material forming flash. In cases where the metal body 110 has a connecting hole, excessively low pressure can also cause indentations in the valve ball at the connecting hole. Furthermore, in cases where the support column 221 can move relative to the inner wall of the mold cavity 201, excessively low or high pressure can easily cause the metal body 110 to shift vertically after losing the support of the support column 221, resulting in uneven thickness of the fluoroplastic layer 120 on the upper and lower sides of the valve ball, affecting the thickness of the fluoroplastic layer 120 on one side. In practical applications, the preset pressure F can be 1MPa, 3.5MPa or 5.5MPa, and can be set according to the actual needs of use.

[0049] In some embodiments, the preset time t2 in the molding and curing step ranges from 10 minutes to 35 minutes. It is understood that by setting the preset time t2 within a range of 10 to 35 minutes (inclusive), the molding time is kept within a suitable range, which helps to avoid the fluoroplastic layer 120 being not properly molded due to an excessively short molding time, or the molding time being too long, thus affecting production efficiency. In practical applications, the preset time t2 can be 10 minutes, 25 minutes, or 35 minutes, and can be set accordingly based on actual usage needs.

[0050] In some embodiments, during the molding and curing step, after the press applies a preset pressure F to the mold assembly 200 and maintains it for a preset time t2, the pressure applied by the press to the mold assembly 200 is gradually reduced while the mold assembly 200 is cooled.

[0051] Understandably, after pressing for a preset time t2 at a preset pressure F, the pressure applied by the press is gradually reduced to accommodate the shrinkage and curing of the fluoropolymer, avoiding deformation caused by instantaneous unloading. At the same time, the mold assembly 200 can be cooled by spraying room temperature water to facilitate the cooling and curing of the internal fluoroplastic layer 120, which facilitates subsequent demolding.

[0052] After the valve ball is produced, it can be inspected to determine whether it meets the production requirements. The inspection method can be visual observation, dimensional measurement, or electric spark test to determine whether the metal is exposed, thereby determining whether the fluoroplastic layer 120 has cracks. In actual application, the specific inspection method can be set according to the actual use needs.

[0053] The embodiments of the present invention have been described in detail above with reference to the accompanying drawings. However, the present invention is not limited to the above embodiments. Within the scope of knowledge possessed by those skilled in the art, various changes can be made without departing from the spirit of the present invention.

Claims

1. A manufacturing process for the valve ball of a fluoropolymer-lined ball valve, characterized in that, The valve ball comprises a metal body and a fluoroplastic layer covering the metal body, and the manufacturing process includes the following steps: The mold is filled with filling material and a mold assembly is set up. The mold assembly is provided with a mold cavity, a feeding channel and a venting hole. The feeding channel and the venting hole are both connected to the mold cavity. An organosilicon insulating varnish layer is coated on the inner wall of the venting hole. The metal body is put into the mold cavity and the mold is closed and locked. Granular fluorine material is added to the feeding channel and the inlet of the feeding channel is closed. Heating and sintering: The mold assembly is placed in a sintering furnace and heated to a preset temperature T and held for a preset time t1, so that the granular fluorine material melts into a fluid. Compression molding and curing: The mold assembly is taken out of the sintering furnace, and a preset pressure F is applied to the mold assembly using a press and held for a preset time t2, so that the fluid fluorine material flows and fully coats and adheres to the metal body. The air bubbles formed in the fluorine material and the excess fluorine material are discharged through the vent hole. After the fluorine material coated on the metal body cools and solidifies, it forms the fluoroplastic layer. The finished product is demolded by opening the mold assembly and removing the valve ball from the mold cavity; The valve ball has a through valve core channel. The mold assembly includes an upper mold base, a lower mold base, a mandrel, and a push rod. The upper mold base and the lower mold base enclose the mold cavity. The feeding channel is located on the upper mold base. The push rod is adapted to the feeding channel. The mandrel is adapted to the valve core channel. The mandrel has a discharge channel inside. The vent is located on the mandrel and communicates with the discharge channel. During the mold filling step, the mandrel is inserted into the metal body and a gap is formed between the mandrel and the metal body to allow the fluorine material to flow in. The push rod is inserted into the feeding channel to block and close the entrance of the feeding channel. During the compression molding and curing step, the press applies a preset pressure F to the push rod, causing the push rod to extrude fluid fluorine material to fill the mold cavity and coat and bond it to the metal body.

2. The manufacturing process of the PTFE-lined ball valve according to claim 1, characterized in that, Before performing the molding and filling steps, the surface of the metal body and the inner wall of the mold cavity are cleaned.

3. The manufacturing process of the PTFE-lined ball valve according to claim 1, characterized in that, The number of exhaust vents shall not exceed three.

4. The manufacturing process of the PTFE-lined ball valve according to claim 1, characterized in that, The diameter of the exhaust port ranges from 1.5 mm to 2.5 mm.

5. The manufacturing process of the valve ball in the PTFE-lined ball valve according to claim 1, characterized in that, In the heating and sintering step, the preset temperature T ranges from 340°C to 350°C.

6. The manufacturing process of the PTFE-lined ball valve according to claim 1, characterized in that, In the heating and sintering step, the preset time t1 ranges from 4h to 11h.

7. The manufacturing process of the valve ball in the PTFE-lined ball valve according to claim 1, characterized in that, In the molding and curing step, the preset pressure F ranges from 1 MPa to 5.5 MPa.

8. The manufacturing process of the valve ball for the PTFE-lined ball valve according to claim 1, characterized in that, In the molding and curing step, the preset time t2 ranges from 10 min to 35 min.

9. The manufacturing process of the valve ball in the PTFE-lined ball valve according to claim 1, characterized in that, In the molding and curing step, after the press applies a preset pressure F to the mold assembly and holds it for a preset time t2, the pressure applied by the press to the mold assembly is gradually reduced while the mold assembly is cooled.

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