A method for processing rubber sealing surface of metal-rubber composite structure valve core

Abstract

A method for machining a rubber sealing surface of a valve core of a metal-rubber composite structure comprises the following steps: step 1, machining to remove excess material of a rubber portion, a pin, and a base, leaving an allowance; step 2, machining to remove material of the pin and base, leaving an allowance; step 3, machining to remove excess material of the rubber portion, leaving an allowance; step 4, using an external cylindrical metal machining knife, feeding the knife from the connecting portion between the rubber portion and the metal, and moving the knife toward the metal, so that the pin and the base meet final dimensional requirements; step 5, using a special rubber knife, machining to remove excess material of the rubber portion, leaving an allowance; step 6, using a special rubber knife, feeding the knife from the connecting portion between the left rubber portion and the base, moving the knife toward the left rubber portion, and when the knife reaches a size equal to the diameter of the pin, moving the knife along the outer diameter generatrix of the pin; step 7, using a special rubber knife, first feeding the knife from the connecting portion between the right rubber portion and the base, and moving the knife toward the right rubber portion, so that the right rubber portion meets final dimensional requirements.

Description

Technical Field

[0001] The invention relates to a method for processing a rubber sealing surface of a valve core with a metal-rubber composite structure, and belongs to the field of liquid rocket engine manufacturing. Background Art

[0002] Rocket engine valves primarily utilize valve cores and valve seat seals. Rubber seals are particularly common, and metal-rubber composite valve cores are widely used. However, the low hardness and elasticity of rubber versus the high strength of metal create a conflicting manufacturing process. Every production batch inevitably encounters issues with sealing surface shape and surface quality. To improve first-pass product quality, reduce the reliance on highly skilled personnel, and lower worker workload, new machining methods are urgently needed.

[0003] The valve core blank consists of four parts as shown in the attached Figure 3 As shown, the rubber grade used in the rubber part is X9319, and the rubber part includes the left rubber part and the right rubber part; the pin is made of 2Cr13 material; the material of the base is 2Cr13; if Figure 3 The right rubber part is replaced by a plastic block. The material of the plastic block is nylon. The processing requirements of the plastic block are the same as those of the right rubber part. The main technical requirements are: ΦA diameter tolerance is The tolerance of angle B° is ±30′, the allowable deviation of the axis runout of the cone relative to the reference A is 0.03mm, and the surface roughness of the cone is Ra0.4. Because the rubber X9319 has a larger cut allowance than the base 2Cr13 during cutting, the design allows the surface of the rubber part of the valve core after processing to be no higher than the base metal surface by no more than 0.05mm. There are no flanging, burrs or other redundant objects at the intersection of the rubber part and the base metal. The valve core can only be cleaned with alcohol.

[0004] In addition, the performance requirements are: the outlet of the electric air valve is blocked, 26Mpa air is introduced, and the air tightness between the valve core and the valve seat is checked, and the leakage is ≤0.1cm3 / S.

[0005] There are three problems with the current processing method:

[0006] 1. The surface size and shape of the base metal and rubber parts are difficult to guarantee; the B°±30′ cone surface of the valve core is composed of two materials, metal and rubber. The cone element line is not straight, and the qualified condition of the angle B°±30′ cannot be checked. When cutting the rubber part, due to the small elastic modulus of rubber and its fast elastic recovery, it is easy to deform during cutting, and it is difficult to control the dimensional accuracy and shape accuracy. It is easy to bite the tool, especially when cutting with a small allowance, it is difficult for the tool to cut off the chips. The tool is responsible for processing both the metal base and the rubber. According to the physical and mechanical properties of rubber, the cutting edge of the tool for processing the base metal will not be very sharp. Generally, the cutting edge radius is about R0.05 or more. Such a tool cannot smoothly cut off excess material when turning rubber with low hardness and high elasticity, resulting in irregularities in the processed surface.

[0007] After processing, the surface of the rubber part is often higher than the substrate surface by B°±30′, with a height of about 0-0.15mm. However, the technical requirements require that the rubber surface be no higher than the substrate metal surface by no more than 0.05mm.

[0008] 2. The surface roughness of rubber materials is difficult to guarantee. During the surface processing of rubber parts, when the blade radius increases and the blade becomes blunt, it becomes difficult to cut. If strong cutting is applied, the rubber will be torn. This will form sawtooth chips, resulting in a rough surface with fish-scale tear marks on the part, which cannot meet the requirements of Ra0.4 of the drawing.

[0009] 3. Burrs and burrs are difficult to remove at the intersection of the rubber and base metal. Metal burrs are embedded in the rubber surface at the intersection of the rubber and base metal of the valve core. When machining this intersection, because rubber is much harder than the base metal (2Cr13 has a hardness of HRC28-32), if the tool is not sharp or the tool is moved from metal to rubber, the burrs and burrs generated during machining will inevitably fall onto the rubber surface. These burrs can fall off at any time due to pressure during valve core operation, forming unwanted debris that does not meet design requirements. Summary of the Invention

[0010] The technical problem to be solved by the present invention is to overcome the shortcomings of the existing technology and solve the problems that the surface size and shape of the base and the rubber part are difficult to ensure, the surface roughness of the rubber material is difficult to ensure, and the burrs and flash at the intersection of the rubber part and the base are difficult to remove.

[0011] The purpose of the present invention is achieved through the following technical solutions:

[0012] A method for processing a rubber sealing surface of a metal-rubber composite structure valve core, comprising:

[0013] Step 1: Rough machining. Use a 95-degree ordinary external turning tool to remove excess material from the rubber part, pin and base metal. All parts should be in accordance with the final size requirements, leaving a 0.5-0.6mm margin;

[0014] Step 2: Semi-finishing the metal. Use a metal and rubber dual-purpose knife to turn away the pin and base metal material, leaving a 0.1-0.2mm margin according to the final size requirements;

[0015] Step 3: Rough processing of rubber. Use a metal and rubber dual-purpose knife to remove excess material from the rubber part, leaving a 0.3-0.4mm margin according to the final size requirements;

[0016] Step 4: Finishing the metal. Use a 95-degree external cylindrical metal cutting tool, first feed from the junction of the rubber part and the metal, then cut towards the metal, to meet the final size requirements of the pin and the base metal in the drawing, and complete the finishing of all parts of the pin and the base metal. (For the structure of metal sandwiched with rubber on the left, there are two cutting paths when turning the metal, namely feed from the junction of metal and rubber, and cut towards the metal, such as Figure 5 shown);

[0017] Step 5: Semi-finishing the rubber part. Use a special rubber knife such as Figure 2 As shown, the excess material of the rubber part is removed by turning, starting from the junction of the rubber part and the base body, and moving towards the rubber part, leaving a margin of 0.06-0.1mm according to the final size requirements;

[0018] Step 6: Finish the conical surface and end surface of the left rubber part. Use a special rubber knife to cut from the connection between the rubber part and the base, and move the knife towards the rubber part (from the outer circle to the inner circle, such as Figure 6 When the cutting tool reaches the same size as the pin diameter, move the tool 0.5mm to the left along the outer circle generatrix of the pin to remove the residual rubber on the pin surface, meet the final size requirements of the left rubber part in the drawing, and complete the finishing of the tapered surface and end face of the rubber part.

[0019] Step 7: Finish the right side of the rubber part. Use a special rubber knife to start from the junction of the rubber part and the base, and then move the knife towards the rubber part to meet the final size requirements of the drawing and complete the finishing of the right side of the rubber part.

[0020] In one embodiment of the present invention, cutting should be the main method, and a larger tool rake angle and clearance angle should be selected. Since the wedge angle of the tool for cutting rubber is very small, the heat dissipation conditions are poor, and the elastic recovery is large and fast, the friction between the tool and the workpiece is aggravated, and the blade is easily blunted. Therefore, a carbide of a grade such as YG8 or YG6X is selected as the tool base, and sufficient cooling and lubrication are added to reduce tool wear. The tool rake angle is 45-60°, and the clearance angle is 20-35°. Figure 2 shown.

[0021] In one embodiment of the present invention, the spindle speed needs to be set twice, once when processing metal materials, generally set at 800-1200 rpm; once when processing rubber materials, generally set at 1200-1800 rpm.

[0022] In one embodiment of the present invention, whether machining metal or rubber, the back cutting depth for semi-finishing is generally 0.1-0.3mm, and the back cutting depth for finishing is generally 0.03-0.1mm. For finishing rubber, the allowance should be ≥ 0.03, otherwise, serious tool deflection will occur. The tool feed rate is generally 0.03-0.06mm / revolution.

[0023] In one embodiment of the present invention, 75% alcohol, which has excellent cooling and lubricating effects, is selected as the cutting fluid during processing to prevent aging or deformation of parts and meet design requirements. When a tool for fine machining metal becomes blunt, metal flanging and burrs may also occur. Therefore, it is necessary to observe carefully and sharpen the tool when necessary.

[0024] In one embodiment of the present invention, the machine tool is a CNC lathe with a spindle radial runout of ≤0.005, a positioning accuracy of ≤0.0015, and a repeat positioning accuracy of ≤0.003.

[0025] Compared with the prior art, the present invention has the following beneficial effects:

[0026] (1) The present invention solves the problem that the size and shape of the metal and rubber parts are difficult to ensure and the flash is difficult to remove, and has the advantages of improving the product shape B ° ± 30 ', The advantage of the position tolerance of 0.03mm is that the surface roughness of the rubber material is improved to Ra0.4;

[0027] (2) The present invention improves the first-time processing qualification rate of products from 89% to 99%, which has the benefit of improving processing efficiency by 30%. In the past, parts with burrs or unqualified rubber surface quality were scrapped because the rework margin was too small;

[0028] (3) The present invention reduces the dependence of production tasks on highly skilled personnel, reduces the labor intensity of workers, has the benefits of energy saving and consumption reduction, and also provides ideas for the processing of some similar products;

[0029] (4) The present invention reduces the economic losses caused by product scrapping, with each product worth 800 yuan, or about 160,000 yuan per year.

[0030] (5) The present invention has the effect of improving production efficiency as a whole, while improving the quality stability of the product, reducing labor intensity, labor costs and waste losses, and has strong practicality and high promotion value. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 For parts drawings;

[0032] Figure 2 is the tool angle diagram;

[0033] Figure 3 It is the part blank drawing;

[0034] Figure 4 is a flow chart of the method steps;

[0035] Figure 5 The tool path when facing metal;

[0036] Figure 6 This is the tool path when facing rubber.

[0037] Reference numerals: 1 - left rubber portion; 2 - pin; 3 - base; 4 - right rubber portion or plastic block. DETAILED DESCRIPTION

[0038] To make the objectives, technical solutions and advantages of the present invention more clear, the embodiments of the present invention will be described in further detail below with reference to the accompanying drawings.

[0039] Example 1:

[0040] A method for processing a rubber sealing surface of a metal-rubber composite valve core, wherein the metal-rubber composite valve core comprises a rubber portion, a pin 2, and a base 3, wherein the rubber portion comprises a left rubber portion 1 and a right rubber portion 4; the left rubber portion 1 and the pin 2 are both assembled on the left side of the base 3, and the left rubber portion 1 is sleeved on the pin 2, and the right rubber portion 4 is assembled on the right side of the base 3; the processing method comprises:

[0041] Preparation:

[0042] 1. Select the tool. Choose YG8 or YG6X grade carbide as the tool base, with the tool rake angle of 60° and back angle of 35°. Figure 2 .

[0043] 2. Select cutting parameters. The spindle speed needs to be set twice: 1200 rpm for metal processing and 1800 rpm for rubber processing. The back cutting depth for semi-finishing is set to 0.3mm, and the back cutting depth for finishing is set to 0.1mm. The allowance for finishing rubber parts should be 0.06mm, and the feed rate should be 0.05mm / rev.

[0044] 3. Select coolant. During processing, choose 75% alcohol as the cutting fluid, which has a good lubrication effect, to prevent parts from aging or deformation and meet design requirements.

[0045] 4. Select a machine tool. Use a CNC lathe with a spindle radial runout of 0.003, a positioning accuracy of 0.001, and a repeatability of 0.002.

[0046] Select below Figure 3 Valve core blank, according to Figure 1 According to the size requirements Figure 4 Processing process.

[0047] Step 1: Rough machining. Use a 95-degree ordinary external turning tool to remove excess material from the rubber part, pin and base metal. All parts should be in accordance with the final size requirements, leaving a 0.5mm margin.

[0048] Step 2: Semi-finishing the metal. Use a metal and rubber dual-purpose knife to turn away the pin and base metal material, leaving a 0.10mm margin according to the final size requirements;

[0049] Step 3: Rough processing of rubber. Use a metal and rubber dual-purpose knife to remove excess material from the rubber part, leaving a 0.3mm margin according to the final size requirements;

[0050] Step 4: Finishing the metal. Use a 95-degree external cylindrical metal cutting tool, first feed from the junction of the rubber part and the metal, then cut towards the metal, to meet the final size requirements of the pin and the base metal in the drawing, and complete the finishing of all parts of the pin and the base metal. (For the structure of metal sandwiched with rubber on the left, there are two cutting paths when turning the metal, namely feed from the junction of metal and rubber, and cut towards the metal, such as Figure 5 shown);

[0051] Step 5: Semi-finishing the rubber part. Use a special rubber knife such as Figure 2 As shown, the excess material of the rubber part is removed by turning, starting from the junction of the rubber part and the base body, and moving towards the rubber part, leaving a 0.06mm margin according to the final size requirements;

[0052] Step 6: Finish the conical surface and end surface of the left rubber part. Use a special rubber knife to cut from the connection between the rubber part and the base, and move the knife towards the rubber part (from the outer circle to the inner circle, such as Figure 6 When the cutting tool reaches the same size as the pin diameter, move the tool 0.5mm to the left along the outer circle generatrix of the pin to remove the residual rubber on the pin surface, meet the final size requirements of the left rubber part in the drawing, and complete the finishing of the tapered surface and end face of the rubber part.

[0053] Step 7: Finish the right side of the rubber part. Use a special rubber knife to start from the junction of the rubber part and the base, and then move the knife towards the rubber part to meet the final size requirements of the drawing and complete the finishing of the right side of the rubber part.

[0054] After a batch of valve cores were trial-processed on CNC lathes, it was found that the straightness of the cone's element line, size, roughness, etc. were compared with the requirements of the design drawings. The results showed that the processing quality of the product was fully qualified and very stable, the product sealing surface was flat and smooth, and the performance met the leakage requirements. There was no metal flange or burr at the intersection of the rubber and the base of the valve core.

[0055] Example 2:

[0056] The right rubber portion 4 in Example 1 is replaced by a plastic block. The processing requirements of the plastic block are the same as those of the right rubber portion 4. The remaining processing methods and steps are the same as those in Example 1.

[0057] The contents not described in detail in the specification of the present invention belong to the common knowledge of those skilled in the art.

[0058] Although the present invention has been disclosed above in terms of preferred embodiments, it is not intended to limit the present invention. Any person skilled in the art may make possible changes and modifications to the technical solutions of the present invention by using the methods and technical contents disclosed above without departing from the spirit and scope of the present invention. Therefore, any simple modifications, equivalent changes and modifications made to the above embodiments based on the technical essence of the present invention without departing from the content of the technical solutions of the present invention shall fall within the scope of protection of the technical solutions of the present invention.

Claims

1. A method for processing the rubber sealing surface of a metal-rubber composite valve core, wherein the metal-rubber composite valve core comprises a rubber portion, a pin, and a base, wherein the rubber portion comprises a left rubber portion and a right rubber portion; the left rubber portion and the pin are both assembled on the left side of the base, and the left rubber portion is sleeved on the pin, and the right rubber portion is assembled on the right side of the base; the pin and the base are both made of metal material; characterized in that: Processing methods include: Step 1, rough machining: Use an external turning tool to remove excess material from the rubber part, pin and base. All parts should be in accordance with the final size requirements, leaving a 0.5-0.6mm margin; Step 2: Semi-finishing metal: Use a metal and rubber dual-purpose knife to turn away the pin and base material, leaving a 0.1-0.2mm margin according to the final size requirements; Step 3: Rough processing of rubber: Use a metal and rubber dual-purpose knife to remove excess material from the rubber part, leaving a 0.3-0.4mm margin according to the final size requirements; Step 4: Finishing the metal: Use an external cylindrical metal cutting tool to cut from the junction of the rubber part and the metal, and then move towards the metal to make the pin and the base meet the final size requirements; Step 5. Semi-finishing the rubber part: Use a special rubber knife to turn away the excess material of the rubber part. Feed the knife from the junction of the rubber part and the substrate, and move the knife towards the rubber part. According to the final size requirements, leave a margin of 0.06-0.1mm; Step 6: Finish the conical surface and end face of the left rubber part: Use a special rubber knife to feed the knife from the junction of the left rubber part and the base body, and move the knife toward the left rubber part. When the knife reaches the same size as the pin diameter, move the knife along the outer circle generatrix of the pin to remove the residual rubber on the pin surface, so that the size of the left rubber part meets the final size requirements. Step 7: Finish the end face of the right rubber part: Use a special rubber knife to start from the junction of the right rubber part and the base, and move the knife towards the right rubber part to make the right rubber part meet the final size requirements.

2. The processing method according to claim 1, characterized in that: The special knife for rubber uses carbide as the tool base, the tool rake angle is 45-60°, and the back angle is 20-35°.

3. The processing method according to claim 1, characterized in that: When processing metal materials, the spindle speed is set at 800-1200 rpm; when processing rubber materials, the spindle speed is set at 1200-1800 rpm.

4. The processing method according to claim 1, characterized in that: When processing metal or rubber materials, the back cutting depth for semi-finishing is 0.1-0.3mm, and the back cutting depth for finishing is 0.03-0.1mm; the allowance for finishing rubber parts should be ≥0.03, and the cutting feed is 0.03-0.06mm / revolution.

5. The processing method according to claim 1, characterized in that: Choose alcohol as cutting fluid; lathe spindle radial runout ≤0.005, positioning accuracy ≤0.0015, repeat positioning accuracy ≤0.

003.

6. A method for processing the rubber sealing surface of a metal-rubber composite valve core, wherein the metal-rubber composite valve core comprises a rubber portion, a pin, a base, and a plastic block; the rubber portion and the pin are both assembled on the left side of the base, with the rubber portion sleeved on the pin, and the plastic block assembled on the right side of the base; the pin and the base are both made of metal material; characterized in that: Processing methods include: Step 1, rough machining: Use an external turning tool to remove excess material from the rubber part, plastic block, pin and base. All parts should be in accordance with the final size requirements, leaving a 0.5-0.6mm margin; Step 2: Semi-finishing metal: Use a metal and rubber dual-purpose knife to turn away the pin and base material, leaving a 0.1-0.2mm margin according to the final size requirements; Step 3: Rough processing of rubber: Use a metal and rubber dual-purpose knife to remove excess material from the rubber part and plastic block, leaving a 0.3-0.4mm margin according to the final size requirements; Step 4: Finishing the metal: Use an external cylindrical metal cutting tool to cut from the junction of the rubber part or plastic block and the metal, and then move the tool towards the metal to make the pin and the base meet the final size requirements; Step 5. Semi-finishing the rubber part and plastic block: Use a special rubber knife to turn away the excess material of the rubber part and plastic block. Feed the knife from the junction of the rubber part or plastic block and the substrate, and move the knife towards the rubber part or plastic block. According to the final size requirements, leave a margin of 0.06-0.1mm. Step 6: Finish the conical surface and end surface of the rubber part: Use a special rubber knife to feed the knife from the junction of the rubber part and the base, and move the knife toward the rubber part. When the knife reaches the same size as the pin diameter, move the knife along the outer circle generatrix of the pin to remove the residual rubber on the pin surface so that the size of the rubber part meets the final size requirements. Step 7: Finish the end face of the plastic block: Use a special rubber knife to start from the junction between the plastic block and the base, and then move the knife towards the plastic block to make the plastic block meet the final size requirements.

7. The processing method according to claim 6, characterized in that: The special knife for rubber uses carbide as the tool base, the tool rake angle is 45-60°, and the back angle is 20-35°.

8. The processing method according to claim 6, characterized in that: When processing metal materials, the spindle speed is set at 800-1200 rpm; when processing rubber materials and plastic blocks, the spindle speed is set at 1200-1800 rpm.

9. The processing method according to claim 6, characterized in that: When processing metal, rubber materials or plastic blocks, the semi-finishing back cutting depth is 0.1-0.3mm, and the finishing back cutting depth is 0.03-0.1mm; the finishing allowance of the rubber part or plastic block should be ≥0.03, and the cutting feed is 0.03-0.06mm / revolution.

10. The processing method according to claim 6, characterized in that: Choose alcohol as cutting fluid; lathe spindle radial runout ≤0.005, positioning accuracy ≤0.0015, repeat positioning accuracy ≤0.003.

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