Finish machining method for large-diameter high-precision thin-wall nickel-copper alloy piston ring forge piece

Abstract

The invention relates to a finish machining method of a forge piece, in particular to a finish machining method of a large-diameter high-precision thin-wall nickel-copper alloy piston ring forge piece, a tool flange is used, and a plurality of evenly-distributed threaded holes are formed in the inner ring and the outer ring of the upper end face of the tool flange respectively; the large-diameter high-precision thin-wall piston ring forge piece is subjected to finish machining in cooperation with a numerical control vertical lathe, different clamping modes are achieved only through different tool flange pressurizing plates, accordingly, the two end faces, the inner hole face and the outer circle face of a piston ring are subjected to finish turning, the clamping pressure is controllable, the influence on the surface quality of the piston ring is reduced to the maximum extent, and the machining efficiency is improved. The method is simple in process, low in manufacturing cost, high in machining efficiency, short in period, good in precision, simple in machining tool and good in flexibility and applicability.

Description

Technical Field

[0001] The invention relates to a forging processing method, in particular to a finishing method for a large-diameter high-precision thin-wall piston ring forging. Background Art

[0002] As a reciprocating component, the piston ring has a relatively high machining accuracy requirement. Excessive shape and position size tolerance will affect the sealing performance and cause the piston ring to get stuck, affecting the function of the piston ring and causing the device to fail. For large-diameter, high-precision, thin-walled nickel-copper alloy piston rings, the nickel-copper alloy material has a fast temperature rise during machining, which is easy to generate heat and is easy to deform during the finishing process, resulting in excessive shape and position size tolerance. In severe cases, the piston ring is scrapped, which prolongs the production cycle and increases the manufacturing cost.

[0003] CN108526937 A A special fixture for processing piston rings and a turning method for processing piston rings, it relates to a fixture and a turning method, which includes a clamp body, a pressure cover, multiple pressure plates and multiple support blocks consistent with the number of pressure plates; the middle part of the clamp body is processed with a positioning groove, the pressure cover is installed in the positioning groove for pressing the piston ring, the outer side of the positioning groove is processed with an annular protrusion for positioning the pressure cover and supporting the piston ring, and the upper end surface of the clamp body is evenly distributed along the circumferential direction. A pressure plate for pressing the piston ring is placed on each support block. The turning method for processing the piston ring is: step one: turning the quasi-inner hole; step two: turning the quasi-outer circle. The present invention ensures that the inner hole and outer circle turning of the piston ring are completed at the same station, thereby improving the processing quality of the piston ring components. The invention purpose of this technical solution is to solve the coaxial problem when processing the inner circle and the outer circle. The following problems still exist: 1) It requires the use of multiple special tools, that is, in addition to the clamping body, corresponding special-shaped pressure covers, pressure plates and support blocks are also required, and the flexibility is poor and cannot adapt to piston rings of different sizes; 2) It can only process the inner circle and outer circle of the piston ring, and cannot perform fine processing on its two end faces, resulting in poor processing efficiency. Summary of the invention

[0004] The present invention aims to solve the above technical problems and provide a finishing method for large-diameter high-precision thin-walled piston ring forgings with simple process, low manufacturing cost, high processing efficiency, good precision, short cycle, simple processing tools and good flexibility.

[0005] The finishing method of the present invention uses a tooling flange, and the inner and outer circles of the upper end surface of the tooling flange are respectively provided with a plurality of evenly distributed threaded holes;

[0006] The following steps are involved:

[0007] 1. Place the tooling flange flat on the chuck of the CNC vertical lathe with the top surface facing upward, clamp it with the chuck claws of the CNC vertical lathe, place the piston ring on the upper end surface of the tooling flange, with any end surface of the piston ring facing upward, and evenly place multiple pressing blocks on the tooling flange outside the piston ring. The end surface of the pressing block contacts the outer cylindrical surface of the piston ring, and the waist-shaped hole on the pressing block is aligned with the outer ring threaded hole of the tooling flange. With the inner hole surface of the piston ring as the reference, use the locking bolt to pass through the waist-shaped hole on the pressing block and fix it to the tooling flange, so as to fix the piston ring to the tooling flange; finish turning any end surface of the piston ring, leaving a single-side finishing allowance of 0.4-0.5mm, and use a dial indicator to check to ensure that the end surface runout is ≤0.02mm;

[0008] 2. Turn the piston ring over with the other end facing upwards, so that any end face of the piston ring fits against the upper end face of the tooling flange. Repeat step 1 to finish turn the other end face of the piston ring, leaving a single-sided finishing allowance of 0.4 to 0.5 mm, and use a dial indicator to check to ensure that the end face runout is ≤ 0.02 mm.

[0009] 3. Finish turning the inner hole surface of the piston ring, leaving a single-side margin of 0.4-0.5mm, ensuring that the cylindricality of the inner hole surface of the piston ring is ≤0.03mm, and record the measured inner hole size D1;

[0010] 4. Remove the piston ring from the tooling flange, and turn the boss on the end face of the tooling flange. The outer circle size of the boss is D2, and the height is 5-6mm. According to the actual measured size D1 of the inner hole of the piston ring, the outer circle of the boss is matched to ensure the interference requirement of 0.02-0.03mm; fix the piston ring to the tooling flange, and the inner hole surface of the piston ring matches the outer circle of the boss of the tooling flange; place multiple pressing blocks evenly, make the end face of the pressing block contact with the inner circle surface of the piston ring, align the waist-shaped hole with the threaded hole of the inner ring of the tooling flange, and use the locking bolt to pass through the waist-shaped hole on the pressing block and fix it to the tooling flange, so as to fix the piston ring to the tooling flange; finish turn the outer circle surface and sealing groove of the piston ring, leave a double-sided polishing allowance of 0.1mm on the outer circle surface, and polish the outer circle surface of the piston ring to the design requirements;

[0011] 5. Take out the piston ring and turn the outer circle of the tooling flange boss to ensure that the outer circle diameter D3 of the boss after turning is ≥30mm smaller than the inner hole surface of the piston ring on one side; place the piston ring on the tooling flange, align it with the outer circle of the piston ring, and ensure that the outer circle runout is ≤0.03mm. Repeat steps 1 to 3, and finish turn any end face, the other end face and the inner hole surface of the piston ring to the design requirements.

[0012] In the step 2, after the piston ring is turned over, any end face of the piston ring is made to fit with the upper end face of the tooling flange, and then the piston ring is manually rotated to grind the end face.

[0013] In step 4, after the piston ring is fixedly installed on the tooling flange, the upper end face of the piston ring is gently tapped with a rubber hammer, and the gap between the lower end face of the piston ring and the upper end face of the tooling flange is checked with a feeler gauge to ensure that no more than 0.03 mm is penetrated.

[0014] In the step 5, the piston ring is taken out from the tooling flange and laid flat for natural aging for ≥ 5 days.

[0015] The upper end surface of the tooling flange is uniformly provided with a plurality of grooves along the circumferential direction, and the front end of the groove extends beyond the position of the outer circumferential surface of the piston ring corresponding to the upper end surface of the tooling flange.

[0016] Measure the thickness of the piston ring through the groove of the tooling flange using an outside diameter micrometer with a range of 25 to 50 mm.

[0017] Beneficial effects:

[0018] 1) The present invention uses only one tooling flange pressure plate as a clamp, which can be used in conjunction with a CNC vertical lathe to achieve fine machining of large-diameter, high-precision, thin-walled piston ring forgings. Different clamping methods are achieved only through different tooling flange pressure plates, so that the two end faces, inner hole face and outer cylindrical face of the piston ring can be fine-turned respectively. The clamping pressure is controllable, which minimizes the impact on the surface quality of the piston ring. The clamping method is simple and effective, and can greatly improve work efficiency. A waist-shaped hole is arranged on the pressure block, which can flexibly control the clamping force, avoid deformation during clamping, and adapt to piston rings of different sizes.

[0019] 2) In order to further improve the accuracy, the other processing surfaces of the piston ring except the outer cylindrical surface are turned twice, and a finishing allowance is left for the first turning to ensure the accuracy of the second turning; each time the piston ring is processed, the two end surfaces are turned first, and then the inner hole surface is processed. This can effectively reduce the deformation of the piston ring during the processing, fully release the processing stress, and ensure the size and shape and position tolerance accuracy of the piston ring.

[0020] 3) When machining the outer cylindrical surface, a boss is machined on the upper end face of the tooling flange so that the piston ring can be mounted on the outer circle of the boss. The inner hole surface and the outer circle of the tooling flange boss have an interference fit to ensure the coaxiality of the inner hole surface and the outer cylindrical surface of the piston ring. At the same time, the contact between the end faces of multiple pressure blocks and the inner cylindrical surface of the piston ring ensures that no deformation occurs during the fine machining of the outer cylindrical surface. Under the above premise, the outer cylindrical surface can be machined to the designed size at one time.

[0021] 4) After the outer cylindrical surface processing is completed, it is placed flat for natural aging for ≥5 days to eliminate stress. After ensuring that the outer cylindrical surface of the piston meets the requirements, a second round of turning is performed. Through the second round of turning, the two end faces and the inner hole surface of the piston ring are processed to the designed size.

[0022] 5) There are multiple grooves evenly opened on the end face of the tooling flange along the circumferential direction. Each time the end face of the piston ring is precision-turned, the thickness of the piston ring in different directions can be conveniently measured through multiple groove positions using a 25-50mm range outside diameter micrometer, thereby further improving the processing accuracy.

[0023] 6) The present invention has the advantages of simple process, low manufacturing cost, high processing efficiency, short cycle, simple processing tools, good flexibility and applicability, and is particularly suitable for the finishing of large-diameter, high-precision, thin-walled nickel-copper alloy piston ring forgings. It has high processing accuracy and can meet the following stringent design requirements: the outer diameter and inner diameter range of the piston ring is φ1250~φ1600mm, the thickness range is 30~50mm, the outer circle dimension tolerance is f7(-0.110~-0.235)mm, the inner hole dimension tolerance is H8(+0.195~0)mm, and the thickness dimension tolerance is f8(-0.025~-0.064)mm. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 Schematic diagram of end face and inner hole processing and clamping;

[0025] Figure 2 Schematic diagram of tooling flange structure;

[0026] Figure 3 Three-dimensional image of the briquette;

[0027] Figure 4 Front view of piston ring;

[0028] Figure 5 Schematic diagram of piston ring outer circle machining and clamping;

[0029] Figure 6 Schematic diagram of tooling flange with boss.

[0030] Among them, 1. tooling flange; 1-1. groove; 1-2. upper end face; 1-3. outer ring threaded hole; 1-4. inner ring threaded hole; 1-5. flange plane; 1-6. boss; 2. pressure block; 2-1 pressure block end face; 2-2. waist-shaped hole; 3. locking bolt; 4. piston ring; 4-1 inner hole surface; 4-2. outer cylindrical surface; 4-3. sealing groove; 4-4 lower end face; 4-5 upper end face. DETAILED DESCRIPTION

[0031] The present invention will be further described below in conjunction with the accompanying drawings.

[0032] The tooling of the present invention comprises a tooling flange 1, a pressure block 2, and a locking bolt 3, wherein the tooling flange 1 is a disc, and the periphery of the upper end surface of the tooling flange is provided with a plurality of grooves 1-1 (8 in this embodiment), and a plurality of threaded holes 1-3 and 1-4 (8 in this embodiment respectively) are evenly distributed in the inner and outer circles; the pressure block 2 has a waist-shaped hole 2-2.

[0033] Processing:

[0034] 1. Place the tooling flange 1 flat on the chuck of the CNC vertical lathe, with the upper end face 1-2 with the groove 1-1 facing upwards, and clamp it with the jaws of the CNC vertical lathe chuck. Polish the upper end face 1-2 of the tooling flange 1 to ensure that the flatness of the upper end face of the tooling flange 1 is ≤0.02mm. Place the piston ring 4 on the upper plane of the tooling flange 1, with the lower end face 4-4 of the piston ring 4 facing upwards, and evenly place the 8 pressure blocks 2, so that the end face 2-1 of the pressure block 2 is in contact with the outer cylindrical surface 4-2 of the piston ring 4, and the waist hole 2-2 is aligned with the outer threaded hole 1-3 of the tooling flange 1, and the piston ring 4 is fixed to the tooling flange 1 with the locking bolt 3 and the pressure block 2. Polish the lower end face 4-4 of the piston ring 4, leaving a single-sided finishing allowance of 0.4 to 0.5mm, and use a dial indicator to check to ensure that the end face runout is ≤0.02mm; when measuring the thickness, measure from the groove 1-1 of the tooling flange 1;

[0035] 2. Loosen the pressure block 2, turn over the piston ring 4, and turn the upper end face 4-5 of the piston ring 4 upwards. After the lower end face 4-4 of the piston ring 4 fits with the upper end face 1-2 of the tooling flange 1, rotate the piston ring 4 a few times, grind the end face to improve the fit, make the pressure block end face 2-1 contact with the outer cylindrical surface 4-2 of the piston ring, align the waist hole 2-2 with the outer ring threaded hole 1-3 of the tooling flange 1, take the inner hole surface 4-1 of the piston ring 4 as the reference, and check the allowance of the outer cylindrical surface 4-2. Use the fastening bolts 3 and the pressure block 2 to fix the piston ring 4 to the tooling flange 1, and finish turn the upper end face 4-5 of the piston ring, leaving a single-sided finishing allowance of 0.4 to 0.5mm. Use a dial indicator to check to ensure that the end face runout is ≤0.02mm. When measuring the thickness, measure from the groove 1-1 of the tooling flange 1;

[0036] 3. Finish turning the inner hole surface 4-1 of piston ring 4, leaving a single-side margin of 0.4-0.5mm, ensuring that the cylindricity of the inner hole surface of piston ring 4 is ≤0.03mm, and record the measured dimension D1 of the inner hole.

[0037] 4. Remove the piston ring 4, and turn the upper end face 1-2 of the tooling flange 1 to form a boss 1-6 located in the center (the boss 1-6 is concentric with the tooling flange 1) and a flange plane 1-5 located around the boss 1-6. The outer circle size D2 of the boss 1-6 is 5 to 6 mm in height. According to the measured inner hole size D1 of the piston ring 4, the outer circle size D2 of the boss 1-6 is matched to ensure the interference requirement of 0.02 to 0.03 mm. Fix the piston ring 4 to the boss 1-6 of the tooling flange 1, and the inner hole surface 4-1 of the piston ring 4 matches the outer circle of the tooling flange boss 1-6. Use a rubber hammer to gently tap the upper end face 4-5 of the piston ring 4, and use a feeler gauge to check the gap between the lower end face 4-4 of the piston ring 4 and the flange plane 1-5 to ensure that 0.03 mm does not enter. Place 8 pressing blocks 2 evenly, make the pressing block end face 2-1 contact with the inner cylindrical surface 4-1 of the piston ring 4, align the waist hole 3-2 with the inner threaded hole 1-3 of the tooling flange 1, and fix the piston ring 4 to the tooling flange with the locking bolt 3 and the pressing block. Finish turning the outer cylindrical surface 4-2 and the sealing groove 4-3 of the piston ring 4, leaving a polishing allowance of 0.1mm on both sides of the outer cylindrical surface, and polish the outer cylindrical surface 4-2 of the piston ring 4 to the requirements. Remove the piston ring 4 from the tooling flange 1.

[0038] 5) After laying flat for natural aging for ≥5 days, re-measure the size of the outer cylindrical surface 4-2 of the piston ring 4. After meeting the requirements, turn the outer cylindrical surface of the boss 1-6 of the tooling flange 1 to ensure that the outer cylindrical diameter D3 of the boss 1-6 is smaller than the inner hole surface 4-1 of the piston ring by ≥30mm on one side, so as to avoid the boss 1-6 affecting the subsequent processing of the inner hole surface 4-1 of the piston ring 4. Place the piston ring 4 on the tooling flange 1, align the outer cylindrical surface of the piston ring 4, ensure the outer cylindrical runout is ≤0.03mm, evenly place 8 pressure blocks 2, make the end face 2-1 of the pressure block 2 contact the outer cylindrical surface 4-2 of the piston ring, align the waist hole 3-2 with the threaded hole 1-3 of the tooling flange 1, and fix the piston ring 4 to the tooling flange 1 with the fastening bolts 3 and the pressure blocks. Finish turning the upper end face 4-5 of the piston ring, and use a dial indicator to check the end face runout ≤0.02mm; turn over, with the lower end face 4-4 of the piston ring 4 facing upwards, and after the upper end face of the piston ring 4 is leveled with the upper end face of the tooling flange 1, rotate the piston ring 4 a few times, grind the end face to improve the fit, and use a feeler gauge to check the gap between the end face of the piston ring and the upper end face of the tooling flange 1 to ensure that 0.03mm does not enter. Make the end face 2-1 of the pressing block contact with the outer cylindrical surface 4-2 of the piston ring, align the waist hole 2-2 with the outer threaded hole 1-3 of the tooling flange 1, and use the fastening bolts 3 and the pressing block 2 to fix the piston ring 4 to the tooling flange 1 with the outer cylindrical surface 4-2 of the piston ring as the reference, and finish turning the lower end face of the piston ring 4, and use a dial indicator to check the end face runout ≤0.02mm, and when measuring the thickness, measure from the groove 1-1 of the tooling flange 1. After the thickness dimension requirements are met, the inner hole surface 4-1 of the piston ring 4 is precision-turned, leaving a polishing allowance of 0.1mm on both sides, and then the inner hole surface 4-1 is polished to the design requirements.

[0039] The method of the present invention can batch produce high-precision thin-walled nickel-copper alloy piston ring forgings with high diameter, high processing efficiency and good precision; 8 piston ring forgings are produced by the above method, and all indicators meet the design requirements after testing: the outer diameter and inner diameter range of the piston ring is φ1250~φ1600mm, the thickness range is 30~50mm, the outer circle dimension tolerance is f7(-0.110~-0.235)mm, the inner hole dimension tolerance is H8(+0.195~0)mm, the thickness dimension tolerance is f8(-0.025~-0.064)mm, and the product processing qualified rate is 100%. Before the above method is adopted, it takes 15 days to fine-process a piston ring, and the local size out-of-tolerance is found in the detection after processing. After the above method is adopted, the fine processing time is reduced to 7 days, and the size out-of-tolerance is not found in the detection after processing.

Claims

1. A finishing method for large-diameter, high-precision, thin-walled nickel-copper alloy piston ring forgings, characterized in that: Use a tooling flange, wherein the inner and outer circles of the upper end surface of the tooling flange are respectively provided with a plurality of evenly distributed threaded holes; The following steps are involved:

1. Place the tooling flange flat on the chuck of the CNC vertical lathe with the top surface facing upward, clamp it with the chuck claws of the CNC vertical lathe, place the piston ring on the upper end surface of the tooling flange, with any end surface of the piston ring facing upward, and evenly place multiple pressing blocks on the tooling flange outside the piston ring. The end surface of the pressing block contacts the outer cylindrical surface of the piston ring, and the waist-shaped hole on the pressing block is aligned with the outer ring threaded hole of the tooling flange. With the inner hole surface of the piston ring as the reference, use the locking bolt to pass through the waist-shaped hole on the pressing block and fix it to the tooling flange, so as to fix the piston ring to the tooling flange; finish turning any end surface of the piston ring, leaving a single-side finishing allowance of 0.4-0.5mm, and use a dial indicator to check to ensure that the end surface runout is ≤0.02mm; 2. Turn the piston ring over with the other end facing upwards, so that any end face of the piston ring fits against the upper end face of the tooling flange. Repeat step 1 to finish turn the other end face of the piston ring, leaving a single-sided finishing allowance of 0.4 to 0.5 mm, and use a dial indicator to check to ensure that the end face runout is ≤ 0.02 mm.

3. Finish turning the inner hole surface of the piston ring, leaving a single-side margin of 0.4-0.5mm, ensuring that the cylindricality of the inner hole surface of the piston ring is ≤0.03mm, and record the measured inner hole size D1; 4. Remove the piston ring from the tooling flange, and turn the boss on the end face of the tooling flange. The outer circle size of the boss is D2, and the height is 5-6mm. According to the actual measured size D1 of the inner hole of the piston ring, the outer circle of the boss is matched to ensure the interference requirement of 0.02-0.03mm; fix the piston ring to the tooling flange, and the inner hole surface of the piston ring matches the outer circle of the boss of the tooling flange; place multiple pressing blocks evenly, make the end face of the pressing block contact with the inner circle surface of the piston ring, align the waist-shaped hole with the threaded hole of the inner ring of the tooling flange, and use the locking bolt to pass through the waist-shaped hole on the pressing block and fix it to the tooling flange, so as to fix the piston ring to the tooling flange; finish turn the outer circle surface and sealing groove of the piston ring, leave a double-sided polishing allowance of 0.1mm on the outer circle surface, and polish the outer circle surface of the piston ring to the design requirements; 5. Take out the piston ring and turn the outer circle of the tooling flange boss to ensure that the outer circle diameter D3 of the boss after turning is ≥30mm smaller than the inner hole surface of the piston ring on one side; place the piston ring on the tooling flange, align it with the outer circle of the piston ring, and ensure that the outer circle runout is ≤0.03mm. Repeat steps 1 to 3, and finish turn any end face, the other end face and the inner hole surface of the piston ring to the design requirements.

2. The finishing method of large-diameter, high-precision, thin-walled nickel-copper alloy piston ring forging according to claim 1, characterized in that: In the step 2, after the piston ring is turned over, any end face of the piston ring is made to fit with the upper end face of the tooling flange, and then the piston ring is manually rotated to grind the end face.

3. The finishing method of large-diameter, high-precision, thin-walled nickel-copper alloy piston ring forging according to claim 1, characterized in that: In step 4, after the piston ring is fixedly installed on the tooling flange, the upper end face of the piston ring is gently tapped with a rubber hammer, and the gap between the lower end face of the piston ring and the upper end face of the tooling flange is checked with a feeler gauge to ensure that no more than 0.03 mm is penetrated.

4. The finishing method of large-diameter, high-precision, thin-walled nickel-copper alloy piston ring forging according to claim 1, characterized in that: In the step 5, the piston ring 4 is taken out from the tooling flange and laid flat for natural aging for ≥ 5 days.

5. The finishing method of large-diameter, high-precision, thin-walled nickel-copper alloy piston ring forgings as described in claims 1-4, characterized in that: The upper end surface of the tooling flange is uniformly provided with a plurality of grooves along the circumferential direction, and the front end of the groove extends beyond the position of the outer circumferential surface of the piston ring corresponding to the upper end surface of the tooling flange.

6. The finishing method of large-diameter, high-precision, thin-walled nickel-copper alloy piston ring forging according to claim 5, characterized in that: Measure the thickness of the piston ring through the groove of the tooling flange using an outside diameter micrometer with a range of 25 to 50 mm.

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