Machining method for high-precision large-diameter fluoroplastic sealing thin-wall workpiece

Abstract

The invention relates to the technical field of machining processes, in particular to a machining method for a high-precision large-diameter fluoroplastic sealing thin-wall workpiece, which aims at machining the fluoroplastic sealing thin-wall workpiece with the diameter of more than phi 200mm and the wall thickness of 0.2-0.7 mm, and comprises the following steps of: 1, blanking to form a fluoroplastic tubular blank; 2, a special tool is customized; 3, the fluoroplastic tubular blank is fixed to a spindle of a numerical control lathe; 4, a numerical control turning tool is configured, and a numerical control turning program is compiled; 5, an inner hole or an outer circle of the fluoroplastic sealing thin-wall workpiece, a matched molded surface and a sealing surface of the fluoroplastic sealing thin-wall workpiece and the O-shaped rubber ring are machined, and finish turning allowance is reserved according to the double wall thickness priority principle; 6, finish turning is conducted on the inner hole or the outer circle in the fluoroplastic sealing thin-wall workpiece and the matched profile of the O-shaped rubber ring; 7, the sealing face of the fluoroplastic sealing thin-wall workpiece is subjected to finish turning, and the wall thickness is guaranteed; and 8, the workpiece is cut off through a cut-off tool by means of a surface constant-speed and small-feed-rate turning method.

Description

Technical Field

[0001] The invention relates to the technical field of machining process, and in particular to a method for machining a high-precision large-diameter fluoroplastic sealed thin-wall workpiece. Background Art

[0002] Currently, the most important factor affecting the life cycle of aviation hydraulic and fuel system products is their sealing device. The combination of fluoroplastic thin-walled protection ring / slip ring and O-type rubber ring is a widely used sealing structure. The fluoroplastic thin-walled protection ring / slip ring can not only effectively prevent the wear of the O-type rubber ring, but also the wear of the fluoroplastic thin-walled protection ring / slip ring can be automatically compensated by the elastic force of the O-type rubber ring. If the thickness of the fluoroplastic thin-walled protection ring / slip ring is large, the elastic force of the O-type rubber ring cannot ensure that the sealing surface of the fluoroplastic thin-walled protection ring / slip ring fits tightly with the product sealing shaft / sealing hole. Therefore, the wall thickness size is a key factor in product design.

[0003] The materials used for high-precision large-diameter fluoroplastic sealing thin-walled workpieces have low mechanical strength. The choice of cutting parameters has a great influence on the resilience and unevenness of the workpiece. When the cutting speed is low and the cutting depth is large, the cut part tilts along the cutting direction and straightens up again after cutting, resulting in poor cutting surface roughness and deviations in size and geometry. Compared with metals, the linear expansion coefficient of fluoroplastics is (10~12)×10 -5 / K, while the linear expansion coefficient of steel is (1~2)×10 -5 / K, which is about 8 to 10 times that of metal. The thermal conductivity of fluoroplastics is also very small, which is 1 / 75 to 1 / 450 of that of steel. Therefore, the processing size of fluoroplastics is very sensitive to temperature. When turning fluoroplastics by conventional methods, a large amount of cutting is often used. Since the workpiece wall is thin and coolant cannot be used, the heat in the processing area will increase, and the heat removal mainly depends on the tool. The tool will stick due to overheating, which seriously affects the surface processing quality and processing accuracy of the workpiece. The cutting of the workpiece is also the key. The processing quality of the cut surface of the workpiece directly determines the success or failure of the overall processing of the workpiece. During the workpiece rotation cutting process, due to the thin wall, normal cutting will cause the entire workpiece to be distorted and severely deformed, resulting in uneven thickness and size of the cut surface. Because the workpiece cannot be processed again after cutting, it is often the case that the rest of the workpiece is processed to be qualified, but the improper cutting method causes the workpiece to be scrapped. Therefore, thin walls and cutting are the biggest difficulties in the processing of high-precision large-diameter fluoroplastic sealing thin-walled workpieces. Conventional processing methods in the industry either fail to produce finished products, or produce finished products with uneven wall thickness and a very low qualified rate. Summary of the invention

[0004] The purpose of the present invention is to provide a high-precision large-diameter fluoroplastic sealed thin-wall workpiece processing method, which can ensure that the wall thickness of the workpiece is uniform and the qualified rate of the finished product reaches 100%.

[0005] The technical solution is as follows:

[0006] A high-precision large-diameter fluoroplastic sealed thin-wall workpiece processing method is aimed at processing fluoroplastic sealed thin-wall workpieces with a diameter exceeding Ф200mm and a wall thickness of 0.2-0.7mm, comprising the following steps:

[0007] Step 1: Cut the fluoroplastic tubular blank according to the size of the fluoroplastic sealing thin-wall workpiece;

[0008] Step 2: Customize special tooling according to the fluoroplastic tubular blank;

[0009] Step 3: Use special tooling to fix the fluoroplastic tubular blank on the spindle of the CNC lathe;

[0010] Step 4: Configure CNC lathe machining tools according to the shape and dimensional accuracy of the fluoroplastic sealing thin-wall workpiece, and compile CNC lathe machining programs;

[0011] Step 5: Run the rough turning and semi-finishing turning procedures to process the inner hole or outer circle of the fluoroplastic sealing thin-wall workpiece, the matching surface with the O-ring and the sealing surface, and reserve the finishing allowance according to the principle of "double wall thickness first";

[0012] Step 6: Run the finishing program, use a diamond external turning tool or a diamond internal turning tool to finish turning the inner hole or outer circle of the fluoroplastic sealed thin-wall workpiece and the matching surface with the O-ring. The processing is divided into multiple times and small feed amounts. After each turning, use compressed air to cool the diamond external turning tool or the diamond internal turning tool;

[0013] Step 7: Run the finishing program and use a diamond-shaped external turning tool or a diamond-shaped internal turning tool to finish the sealing surface of the fluoroplastic sealing thin-wall workpiece to ensure the wall thickness;

[0014] Step 8: Run the cutting program and use the cutting tool to cut the workpiece using a turning method with constant surface speed and small feed.

[0015] Preferably, the sealing surface diameter of the fluoroplastic sealing thin-wall workpiece exceeds Ф200 mm, and the dimensional accuracy tolerance reaches level 7.

[0016] Preferably, in steps 2 and 3, the special tooling is a mandrel clamp or a threaded matching clamp. When the mandrel clamp is used, the inner hole of the fluoroplastic tubular blank is supported by the outer circle of the mandrel clamp, and the fluoroplastic tubular blank is clamped by the three-jaw chuck of a CNC lathe; when the threaded matching clamp is used, the internal thread or external thread of the threaded matching clamp is matched with the external thread or internal thread of the fluoroplastic tubular blank, the fluoroplastic tubular blank is tightened, and then the threaded matching clamp is clamped by the three-jaw chuck of the CNC lathe.

[0017] Preferably, in step 5, the principle of "double wall thickness priority" is that the reserved finishing allowances of the inner hole or outer circle of the workpiece, the mating surface with the O-ring rubber ring and the sealing surface are twice the wall thickness of the workpiece.

[0018] Preferably, in step 6, when precision turning the mating surface between the fluoroplastic sealing thin-wall workpiece and the O-ring rubber ring, a diamond-shaped external cylindrical turning tool or a diamond-shaped internal hole turning tool with a cutting angle of 35° is selected according to the mating surface space, or a diamond-shaped external cylindrical turning tool or a diamond-shaped internal hole turning tool with a cutting angle of 80° is selected.

[0019] Preferably, when the mating surface space is L-shaped, a diamond-shaped external cylindrical turning tool or a diamond-shaped internal hole turning tool with a cutting angle of 80° is selected; when the mating surface space is concave or inverted concave, a diamond-shaped external cylindrical turning tool or a diamond-shaped internal hole turning tool with a cutting angle of 35° is selected.

[0020] Preferably, in step 7, a diamond-shaped external cylindrical turning tool or a diamond-shaped internal hole turning tool with a cutting angle of 80° is used to precision-turn the sealing surface of the fluoroplastic sealing thin-wall workpiece.

[0021] Preferably, when a mandrel fixture is used in step 7, the outer circle of the mandrel fixture supports the inner hole of the fluoroplastic tubular blank, and a temporary process blocking groove is radially processed in the fluoroplastic tubular blank in front of the sealing surface of the fine-turned fluoroplastic sealing thin-walled workpiece to effectively ensure uniform wall thickness.

[0022] Preferably, in step 8, the cutting program is run, and when the cutting tool is used for cutting, the surface linear velocity is maintained at V=150-300 m / min and the feed rate f=0.02-0.05 mm / r to cut the workpiece.

[0023] Preferably, the cutting is performed with a cutting tool, the cutting tool material is high-speed steel, the tool rake angle γ=15°~25°, the tool back angle α=20°~30°, and the chip groove R=5mm~10mm.

[0024] Beneficial effects of the present invention:

[0025] The invention discloses a high-precision large-diameter fluoroplastic sealed thin-wall workpiece processing method. The method is for fluoroplastic sealed thin-wall workpieces with a diameter exceeding 200 mm and a wall thickness of (0.2-0.7) mm. The main steps are: fixing a fluoroplastic tubular blank on a spindle of a numerically controlled lathe in combination with a customized special tooling; firstly, rough turning and semi-finishing turning the inner hole or outer circle of the fluoroplastic sealed thin-wall workpiece, the matching profile and sealing surface with an O-type rubber ring, reserving a fine turning margin according to the principle of "double wall thickness first", and then fine turning the inner hole or outer circle of the fluoroplastic sealed thin-wall workpiece and the matching profile with the O-type rubber ring; during the processing, a processing method of multiple times and small feed amount is applied; after each turning, compressed air is used to cool the tool; then, the sealing surface of the fluoroplastic sealed thin-wall workpiece is fine turned to ensure the wall thickness; finally, a turning method with a surface constant speed and small feed amount is adopted to cut the workpiece.

[0026] The invention solves the problem that the traditional processing method cannot ensure the wall thickness size of the high-precision large-diameter fluoroplastic sealing thin-wall workpiece and the qualified rate of the finished product is low. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 It is a schematic diagram of the method of the present invention.

[0028] Among them, 1, workpiece, 2-1, spindle fixture, 3-1, diamond turning tool for finishing surface, 3-2, diamond turning tool for finishing sealing surface, 4-cutting tool;

[0029] Figure 2 This is a schematic diagram of the processing of L-shaped fluoroplastic slip rings with a wall thickness of 0.7mm.

[0030] Among them, 1-workpiece, 2-2, thread matching tooling, 3-1, diamond turning tool for finishing the surface, 3-2, diamond turning tool for finishing the sealing surface, 4-cutting tool;

[0031] Figure 3 This is a schematic diagram of the processing of a concave-shaped 0.2mm thick fluoroplastic protective ring.

[0032] Among them, 1-workpiece, 2-1, spindle fixture, 3-1, diamond turning tool for fine turning of surface, 3-2, diamond turning tool for fine turning of sealing surface, 4-cutting tool. DETAILED DESCRIPTION

[0033] The present invention will be further described below in conjunction with the accompanying drawings:

[0034] The first embodiment of the present invention, see Figure 1 A high-precision large-diameter fluoroplastic sealed thin-wall workpiece processing method is used for processing fluoroplastic sealed thin-wall workpieces with a diameter exceeding Ф200mm and a wall thickness of 0.2 to 0.7mm. The method comprises:

[0035] Step 1: Cut the fluoroplastic sealing thin-wall workpiece 1 into a fluoroplastic tubular blank according to the size; the sealing surface diameter of the fluoroplastic sealing thin-wall workpiece 1 exceeds Ф200mm, and the dimensional accuracy tolerance reaches level 7;

[0036] Step 2: Customize special tooling according to the fluoroplastic tubular blank;

[0037] Special tooling for workpieces of different shapes:

[0038] The special tooling may be a mandrel fixture 2-1, which supports the inner hole of the fluoroplastic tubular blank through the outer circle of the mandrel fixture 2-1, and clamps the fluoroplastic tubular blank with a three-jaw chuck of a CNC lathe.

[0039] Among them, the special tooling can be a threaded matching fixture 2-2, through which the internal thread of the threaded matching fixture 2-2 is matched with the external thread of the fluoroplastic tubular blank, the fluoroplastic tubular blank is tightened, and then the threaded matching fixture 2-2 is clamped with a three-jaw chuck of a CNC lathe. When the special tooling is a threaded matching fixture 2-2, the external thread of the threaded matching fixture 2-2 can also be matched with the internal thread of the fluoroplastic tubular blank, the fluoroplastic tubular blank is tightened, and then the threaded matching fixture 2-2 is clamped with a three-jaw chuck of a CNC lathe.

[0040] Step 3: Fix the fluoroplastic tubular blank on the spindle of the CNC lathe by using customized special tooling;

[0041] Step 4: Configure CNC lathe machining tools according to the shape and dimensional accuracy of the fluoroplastic sealing thin-wall workpiece 1, and compile CNC lathe machining programs, which include rough lathe programs, semi-finishing lathe programs, and finishing lathe programs;

[0042] Step 5: Run the rough turning and semi-finishing turning procedures to process the inner hole or outer circle of the fluoroplastic sealing thin-wall workpiece 1, the matching surface with the O-type rubber ring and the sealing surface, and reserve the finishing allowance according to the principle of "double wall thickness first";

[0043] When rough turning and semi-finishing the inner hole and outer circle of a fluoroplastic sealed thin-walled workpiece 1, reserve a finishing allowance based on the principle of "double wall thickness priority". The principle of "double wall thickness priority" means that the reserved allowances for the inner hole or outer circle, the mating surface with the O-ring and the sealing surface are twice the wall thickness of the workpiece respectively. The wall thickness of the workpiece refers to the thickness between the bottom diameter of the workpiece sealing surface and the mating surface of the O-ring.

[0044] Step 6: Run the finishing program, use a diamond external cylindrical turning tool or a diamond internal hole turning tool to finish turning the inner hole or outer circle of the fluoroplastic sealed thin-walled workpiece 1 and the matching surface with the O-ring, and use a processing method with multiple times and small feed rate during processing. Use compressed air to cool the diamond external cylindrical turning tool or the diamond internal hole turning tool 3 after each turning; wherein, the matching surface of the fluoroplastic sealed thin-walled workpiece 1 and the O-ring can be L-shaped, can be concave, and can be inverted concave.

[0045] Among them, when fine turning the mating surface of the fluoroplastic sealing thin-wall workpiece 1 and the O-ring rubber ring, a diamond outer circle turning tool or a diamond inner hole turning tool with a cutting angle of 35° is selected according to the mating surface space, or a diamond outer circle turning tool or a diamond inner hole turning tool with a cutting angle of 80° is selected, such as Figure 1 Diamond turning tool 3-1 for fine surface machining.

[0046] Among them, when the matching surface of the fluoroplastic sealing thin-wall workpiece 1 and the O-type rubber ring is finely turned, when the matching surface space is L-shaped, a diamond outer circle turning tool or a diamond inner hole turning tool with a cutting angle of 80° is selected; when the matching surface space is concave or inverted concave, a diamond outer circle turning tool or a diamond inner hole turning tool with a cutting angle of 35° is selected, such as Figure 1 Diamond turning tool 3-1 for fine surface machining.

[0047] Step 7: Run the finishing program, use a diamond external turning tool or a diamond internal turning tool to finish turning the sealing surface of the fluoroplastic sealing thin-wall workpiece to ensure the wall thickness; use a diamond external turning tool or a diamond internal turning tool with a cutting angle of 80° to finish turning the sealing surface of the fluoroplastic sealing thin-wall workpiece 1, such as Figure 1 The diamond-shaped turning tool 3-2 for finishing the sealing surface is shown;

[0048] During the fine turning process, when the mandrel fixture 2-1 is used, the outer circle of the mandrel fixture 2-1 supports the inner hole of the fluoroplastic tubular blank, and before the sealing surface of the fine turning fluoroplastic sealing thin-walled workpiece 1, a temporary process blocking groove is radially processed in the fluoroplastic tubular blank to effectively ensure uniform wall thickness.

[0049] Step 8: Run the cutting program, use the cutting tool 4, and apply the surface constant speed and small feed amount turning method to cut the workpiece, wherein the cutting is performed using the cutting tool (4), the material of the cutting tool (4) is high-speed steel, the tool rake angle γ = 15° ~ 25°, the tool back angle α = 20° ~ 30°, and the chip groove R = 5mm ~ 10mm.

[0050] A second embodiment of the present invention is:

[0051] This embodiment sees Figure 2 , a processing method for an L-shaped 0.7mm thick fluoroplastic slip ring, sealing surface diameter Inner hole diameter Processing methods include:

[0052] Step 1: Cut the fluoroplastic sealing thin-wall workpiece 1 into a fluoroplastic tubular blank of Ф400×25 according to the size;

[0053] Step 2: Turn the external thread according to the fluoroplastic tubular blank, and customize the thread matching fixture 2-2, and screw the blank into the internal thread of the customized thread matching fixture 2-2;

[0054] Step 3: Fix the customized thread matching fixture 2-2 on the spindle of the CNC lathe;

[0055] Step 4: Configure CNC lathe machining tools according to the shape and dimensional accuracy of the fluoroplastic sealing thin-wall workpiece 1, and compile a CNC lathe machining program;

[0056] Step 5: Run the rough turning and semi-finishing turning procedures to process the inner hole of the fluoroplastic sealing thin-wall workpiece 1, the matching surface with the O-type rubber ring and the sealing surface. According to the principle of "double wall thickness first", the inner hole of the workpiece, the matching surface with the O-type rubber ring and the sealing surface are reserved with a finishing allowance of 1.4mm;

[0057] Step 6: Run the finishing program, use the inner hole turning tool with 80° diamond blade to finish turning the inner hole of the fluoroplastic sealed thin-wall workpiece 1 and the matching surface with the O-ring, and turn it in 4 times, with the feed amount of 0.5mm, 0.5mm, 0.3mm, and 0.1mm each time. In the program, a pause is set for each turning, and the inner hole turning tool with 80° diamond blade is cooled with compressed air and the accumulated chips are cleaned;

[0058] Step 7: Run the finishing program, use an external turning tool with an 80° diamond blade to finish turning the sealing surface of the fluoroplastic sealed thin-wall workpiece 1, and turn it in 4 times, with each feed amount of 0.5mm, 0.5mm, 0.3mm, and 0.1mm respectively. In the program, a pause is set for each turning, and the external turning tool with an 80° diamond blade is cooled with compressed air and the accumulated chips are cleaned to ensure that the wall thickness is 0.7mm;

[0059] Step 8: Run the cutting program and use the cutting tool 4 to cut the workpiece with the surface linear speed maintained at V=200m / min and the feed rate f=0.03mm / r.

[0060] The processing method of this embodiment can ensure that the wall thickness of the workpiece is 0.7 mm, the thickness is uniform, and the qualified rate of the finished product reaches 100%.

[0061] A third embodiment of the present invention is:

[0062] This embodiment sees Figure 3 , a method for processing a fluoroplastic slip ring with an inverted concave wall thickness of 0.2 mm, the sealing surface diameter Inner hole diameter Processing methods include:

[0063] Step 1: Cut the fluoroplastic sealing thin-wall workpiece 1 into a fluoroplastic tubular blank of Ф240×30 according to the size;

[0064] Step 2: Customize the mandrel fixture 2-1 according to the inner hole size of the fluoroplastic tubular blank;

[0065] Step 3: Install the customized mandrel fixture 2-1 into the inner hole of the fluoroplastic tubular blank, and clamp the fluoroplastic tubular blank with a three-jaw chuck of a CNC lathe;

[0066] Step 4: Configure CNC lathe machining tools according to the shape and dimensional accuracy of the fluoroplastic sealing thin-wall workpiece 1, and compile a CNC lathe machining program;

[0067] Step 5: Run the rough turning and semi-finishing turning procedures to process the inner hole of the fluoroplastic sealing thin-wall workpiece 1, the matching surface with the O-type rubber ring and the sealing surface. According to the principle of "double wall thickness first", the inner hole of the workpiece, the matching surface with the O-type rubber ring and the sealing surface are reserved with a finishing allowance of 0.4mm;

[0068] Step 6: Run the finishing program, use the inner hole turning tool with a 35° diamond blade to finish turning the inner hole of the fluoroplastic sealed thin-wall workpiece 1 and the matching surface with the O-ring, and turn it twice, with the feed amount of 0.3mm and 0.1mm respectively each time. In the program, a pause is set for each turning, and the inner hole turning tool with a 35° diamond blade is cooled with compressed air and the accumulated chips are cleaned;

[0069] Step 7: Run the finishing program, use an external turning tool with an 80° diamond blade to finish turning the sealing surface of the fluoroplastic sealed thin-wall workpiece 1, and turn it twice, with a feed rate of 0.3mm and 0.1mm each time. In the program, a pause is set for each turning, and compressed air is used to cool the external turning tool with an 80° diamond blade and clean the accumulated chips to ensure that the wall thickness is 0.2mm;

[0070] Step 8: Run the cutting program and use the cutting tool 4 to cut the workpiece with the surface linear speed maintained at V=150m / min and the feed rate f=0.02mm / r.

[0071] The processing method of this embodiment can ensure that the wall thickness of the workpiece is 0.2 mm, the thickness is uniform, and the qualified rate of the finished product reaches 100%.

Claims

1. A high-precision large-diameter fluoroplastic sealed thin-walled workpiece processing method, for the processing of fluoroplastic sealed thin-walled workpieces with a diameter exceeding Ф200mm and a wall thickness of 0.2-0.7mm, characterized in that: The following steps are involved: Step 1: Cut the fluoroplastic tubular blank according to the size of the fluoroplastic sealing thin-wall workpiece; Step 2: Customize special tooling according to the fluoroplastic tubular blank; Step 3: Use special tooling to fix the fluoroplastic tubular blank on the spindle of the CNC lathe; Step 4: Configure CNC lathe machining tools according to the shape and dimensional accuracy of the fluoroplastic sealing thin-wall workpiece, and compile CNC lathe machining programs; Step 5: Run the rough turning and semi-finishing turning procedures to process the inner hole or outer circle of the fluoroplastic sealing thin-wall workpiece, the matching surface with the O-ring and the sealing surface, and reserve the finishing allowance according to the principle of "double wall thickness first"; Step 6: Run the finishing program, use a diamond external turning tool or a diamond internal turning tool to finish turning the inner hole or outer circle of the fluoroplastic sealed thin-wall workpiece and the matching surface with the O-ring. The processing is divided into multiple times and small feed amounts. After each turning, use compressed air to cool the diamond external turning tool or the diamond internal turning tool; Step 7: Run the finishing program and use a diamond-shaped external turning tool or a diamond-shaped internal turning tool to finish the sealing surface of the fluoroplastic sealing thin-wall workpiece to ensure the wall thickness; Step 8: Run the cutting program and use the cutting tool to cut the workpiece using a turning method with constant surface speed and small feed.

2. A high-precision large-diameter fluoroplastic sealed thin-wall workpiece processing method according to claim 1, characterized in that: The sealing surface diameter of fluoroplastic sealing thin-walled workpiece exceeds Ф200mm, and the dimensional accuracy tolerance reaches level 7.

3. A high-precision large-diameter fluoroplastic sealed thin-wall workpiece processing method according to claim 2, characterized in that: In steps 2 and 3, the special tooling is a mandrel fixture or a thread matching fixture. When the mandrel fixture is used, the inner hole of the fluoroplastic tubular blank is supported by the outer circle of the mandrel fixture, and the fluoroplastic tubular blank is clamped by the three-jaw chuck of the CNC lathe; when the thread matching fixture is used, the internal thread or external thread of the thread matching fixture is matched with the external thread or internal thread of the fluoroplastic tubular blank, the fluoroplastic tubular blank is tightened, and then the thread matching fixture is clamped by the three-jaw chuck of the CNC lathe.

4. A high-precision large-diameter fluoroplastic sealed thin-wall workpiece processing method according to claim 3, characterized in that: In step 5, the principle of "double wall thickness priority" is that the reserved finishing allowances for the inner hole or outer circle of the workpiece, the mating surface with the O-ring rubber ring and the sealing surface are twice the wall thickness of the workpiece.

5. A high-precision large-diameter fluoroplastic sealed thin-wall workpiece processing method according to claim 4, characterized in that: In step 6, when fine turning the mating surface between the fluoroplastic sealing thin-wall workpiece and the O-ring rubber ring, a diamond-shaped external cylindrical turning tool or a diamond-shaped internal hole turning tool with a cutting angle of 35° is selected according to the mating surface space, or a diamond-shaped external cylindrical turning tool or a diamond-shaped internal hole turning tool with a cutting angle of 80° is selected.

6. A high-precision large-diameter fluoroplastic sealed thin-wall workpiece processing method according to claim 5, characterized in that: When the mating surface space is L-shaped, select a diamond-shaped external cylindrical turning tool or a diamond-shaped internal hole turning tool with an 80° cutting angle; when the mating surface space is a concave shape or an inverted concave shape, select a diamond-shaped external cylindrical turning tool or a diamond-shaped internal hole turning tool with a 35° cutting angle.

7. A high-precision large-diameter fluoroplastic sealed thin-wall workpiece processing method according to claim 6, characterized in that: Step 7: Use a diamond-shaped external cylindrical turning tool or a diamond-shaped internal hole turning tool with a cutting angle of 80° to fine-turn the sealing surface of the fluoroplastic sealing thin-wall workpiece.

8. A high-precision large-diameter fluoroplastic sealed thin-wall workpiece processing method according to claim 7, characterized in that: When the mandrel fixture is used in step 7, the outer circle of the mandrel fixture supports the inner hole of the fluoroplastic tubular blank, and the sealing surface of the fluoroplastic sealing thin-walled workpiece is precision-turned. A temporary process blocking groove is radially processed in the fluoroplastic tubular blank to effectively ensure uniform wall thickness.

9. A high-precision large-diameter fluoroplastic sealed thin-wall workpiece processing method according to claim 8, characterized in that: In step 8, the cutting program is run, and when the cutting tool is used for cutting, the surface linear velocity is maintained at V=150-300 m / min and the feed rate f=0.02-0.05 mm / r to cut the workpiece.

10. A high-precision large-diameter fluoroplastic sealed thin-wall workpiece processing method according to claim 9, characterized in that: The cutting is performed with a cutting tool, the cutting tool material is high-speed steel, the tool rake angle γ = 15° ~ 25°, the tool back angle α = 20° ~ 30°, and the chip groove R = 5mm ~ 10mm.

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