A barrel numerical control machining coaxiality on-line regulation and control process method

Abstract

The present application relates to the technical field of alloy metal processing, and a barrel numerical control processing coaxiality online regulation and control process method, S1, preparing barrel raw materials, center hole processing is carried out on both ends; S2, detecting the coaxiality of the center holes on both ends of the barrel; S3, rough processing the barrel, rough turning the barrel and reserving processing allowance; S4, detecting the bending deformation of the barrel, straightening and stress relieving, and detecting whether the processing allowance is uniform; S5, semi-finishing the barrel, reserving 0.4mm finishing allowance; S6, detecting whether the finishing allowance is uniform, and heat treating the barrel; S7, finishing, after the machine tool is preheated for 10 minutes in a constant temperature environment, first tooling is carried out, 0.2mm processing allowance is reserved after the first tooling, and second reverse tooling is carried out for final processing. Through the processes of rough processing, semi-finishing and finishing, the coaxiality precision is greatly improved.

Description

Technical Field

[0001] This invention relates to the field of alloy metal processing technology, and in particular to a method for online control of coaxiality in CNC machining of tubes. Background Technology

[0002] As a core component of artillery, the quality of deep-hole machining of the barrel directly determines the weapon's firing accuracy, range, and service life. The barrel is a typical slender rod-like part, with a very high length-to-diameter ratio during deep-hole machining, resulting in significant coaxiality errors.

[0003] The following are the reasons for the large coaxiality error: poor machining quality of the center holes at both ends and small contact area, resulting in the accumulation of clamping and positioning errors; residual stress release after rough machining causes bending deformation, and there is a lack of effective online detection and control methods; the traditional quenching cooling method has a large temperature gradient, resulting in uneven thermal deformation of the tube; single-pass machining is prone to tool deflection error, and the influence of machine tool thermal deformation and ambient temperature on machining accuracy is not considered.

[0004] Currently, the barrel manufacturing process is not optimized enough, resulting in a coaxiality error that is usually above 0.15mm, which makes it difficult to meet the requirements of high-precision weapon systems. Summary of the Invention

[0005] The purpose of this invention is to solve the problem of large coaxiality error in the existing technology of tube machining, and to propose an online coaxiality control process method for CNC machining of tubes.

[0006] To achieve the above objectives, the present invention adopts the following technical solution: A method for online control of coaxiality in CNC machining of tubes is designed, and the specific steps are as follows: S1. Prepare the raw material for the tube and machine the center holes at both ends; S2. Perform coaxiality testing on the center holes at both ends of the tube; S3. Rough machining of the tube, rough turning of the tube with a machining allowance reserved; S4. Inspect the bending deformation of the tube, straighten and relieve stress, and check whether the machining allowance is uniform. S5. Perform semi-finishing on the tube, leaving a 0.4mm finishing allowance; S6. Check whether the finishing allowance is uniform and perform heat treatment on the tube; S7. Finishing: After the machine tool has been preheated for 10 minutes in a constant temperature environment, perform the first pass. After the first pass, leave a machining allowance of 0.2mm. Perform the final machining with the second reverse pass.

[0007] Preferably, the contact area of ​​the center holes at both ends in S1 is greater than 80%, and the radial runout of the fixture is detected before processing.

[0008] Preferably, in step S2, a coordinate measuring machine is used for inspection, and the coaxiality error of the center holes at both ends is no greater than 0.05 mm.

[0009] Preferably, the machining allowance in S3 is 2-4mm.

[0010] Preferably, in step S4, stress relief is achieved using a low-temperature stress-relief annealing method, maintaining a temperature of 190-260 degrees Celsius for 2-4 hours.

[0011] Preferably, the S6 heat treatment involves maintaining the body temperature at 500-600 degrees Celsius for 2 hours, and using a mixture of polyethylene glycol solution and water, with cooling achieved by spraying in an atomized form, and the temperature difference per minute not exceeding 10 degrees Celsius.

[0012] The present invention proposes an online coaxiality control process for CNC machining of tubes, the advantages of which are as follows: 1. By using the radial runout detection of the fixture and the grinding process of the center hole, we ensure that the contact area of ​​the center holes at both ends is greater than 80% and the coaxiality error is no greater than 0.05mm, thus reducing the clamping and positioning error from the source.

[0013] 2. After rough machining, a laser alignment instrument is used to detect bending deformation online and perform precise straightening. Combined with a low-temperature stress-relief annealing process, more than 90% of the residual stress is eliminated, avoiding stress release deformation in subsequent processing.

[0014] 3. The atomized spray cooling method is adopted, combined with the slow cooling effect of polyethylene glycol aqueous solution, so that the temperature gradient is uniform during the cooling process of the tube, the temperature difference per minute is no more than 10℃, and the coaxiality deformation after heat treatment is controlled within 0.02mm.

[0015] 4. Precision machining is performed in a constant temperature environment, and machine tool preheating eliminates the effects of thermal deformation; a two-way tool feed process is adopted, with the first feed eliminating most of the tool deflection error and the second reverse feed ensuring the final machining accuracy. Attached Figure Description

[0016] Figure 1 This is a schematic diagram of the online coaxiality control process for CNC machining of tubes according to the present invention. Detailed Implementation

[0017] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments.

[0018] This embodiment provides a method for online control of coaxiality in CNC machining of tubes. S1. Prepare the raw materials for the tube. First, perform a radial runout test on the three-jaw chuck of the CNC lathe. The radial runout of the chuck was measured to be 0.008mm using a dial indicator, which meets the requirements. Then, use a carbide grinding head to grind the center holes at both ends at a grinding speed of 120r / min. The contact area of ​​the center holes at both ends was measured to be 85%. S2. The coaxiality of the center holes at both ends was checked using a coordinate measuring machine. The coaxiality error was measured to be 0.03mm, which meets the requirements. S3. Use a CNC lathe to rough turn the outer diameter. The cutting speed is 60m / min, the feed rate is 0.2mm / r, and the machining allowance on one side is 3mm. S4. The bending deformation of the tube was detected using a laser alignment instrument, and the maximum bending amount was measured to be 0.12 mm. Straightening was performed using a pressure straightening machine, and the straightness error after straightening was 0.04 mm / m. Then, a low-temperature stress-relief annealing treatment was carried out, with the temperature raised to 220℃, held for 3 hours, and then cooled to room temperature in the furnace. After stress relief, the machining allowance was measured every 100 mm along the axial direction of the tube using a micrometer, and the deviation of the machining allowance at each section was measured to be 0.15 mm, which meets the requirements. S5. Use a CNC lathe to perform semi-finish turning of the outer diameter, with a cutting speed of 70m / min, a feed rate of 0.15mm / r, and a 0.4mm finishing allowance on each side; S6. Using a micrometer, the finishing allowance of each section was checked every 50 mm along the axial direction of the tube. The deviation of the finishing allowance of each section was measured to be 0.03 mm, which meets the requirements. Then, the tube was heat-treated by placing it in a pit furnace and heating it to 550°C for 2 hours. Subsequently, a ring-shaped atomizing spray device was used for cooling. The spray solution was a mixture of polyethylene glycol and water in a volume ratio of 1:3. The spray pressure was 0.25 MPa, and the temperature difference was controlled at 8°C per minute until it cooled to room temperature. S7. Control the machining environment temperature at 20℃, start the CNC lathe and preheat for 10 minutes; then perform the first pass, with a cutting speed of 90m / min and a feed rate of 0.12mm / r, and leave a machining allowance of 0.2mm on one side after the pass; finally, perform the second reverse pass, with a cutting speed of 130m / min and a feed rate of 0.06mm / r, to complete the final machining.

[0019] The coaxiality error of the tube processed by the present invention is stably controlled within 0.03mm, and the average coaxiality reaches 0.022mm, which is 75% higher than that of the traditional process; Cylindricity and straightness accuracy have also been significantly improved, with good consistency in accuracy among products in the same batch, and the coaxiality error fluctuation range is only 0.009mm.

[0020] The following three embodiments are all based on the process framework of the present invention. By adjusting the key process parameters, differentiated solutions are formed. All solutions can achieve the core technical indicator of coaxiality error ≤0.03mm, and the accuracy is consistent.

[0021] Example 1: Low-temperature long-term stress relief process: This solution focuses on extending the low-temperature stress relief holding time to more thoroughly eliminate residual stress from rough machining, and is suitable for machining ultra-long tubes with a length-to-diameter ratio > 25.

[0022] S1 reference preparation: Radial runout of the three-jaw chuck of the CNC lathe was tested, and the runout value was measured to be 0.007 mm by a dial indicator; the center holes at both ends were ground with a carbide grinding head at a speed of 100 r / min, and the contact area of ​​the center holes was measured to be 82%.

[0023] S2 datum coaxiality test: The coaxiality of the center holes at both ends was tested using a coordinate measuring machine, and the measured error was 0.02mm, which meets the requirements.

[0024] S3 roughing: Rough turning of the outer diameter on a CNC lathe, cutting speed 55m / min, feed rate 0.18mm / r, with a single-sided machining allowance of 2.5mm.

[0025] S4 Deformation Control and Stress Relief: The maximum bending amount of the tube was measured to be 0.15mm by the laser alignment instrument; the straightness error after pressure straightening was 0.035mm / m; low-temperature stress relief annealing was adopted, with the temperature raised to 200℃ and held for 4 hours, and then cooled to room temperature in the furnace; the machining allowance was measured every 100mm along the axis with a micrometer, and the allowance deviation of each section was 0.12mm.

[0026] S5 Semi-finishing: Semi-finish turning of the outer diameter on a CNC lathe, cutting speed 65m / min, feed rate 0.14mm / r, with a 0.4mm finishing allowance on one side.

[0027] S6 Heat Treatment and Allowance Inspection: The allowance for precision machining is inspected every 50mm along the axial direction with a micrometer, and the allowance deviation for each section is 0.02mm; the pit furnace is heated to 520℃ and held for 2 hours; the ring-shaped atomizing spray is used for cooling, and the spray solution is a mixture of polyethylene glycol and water in a ratio of 1:4. The spray pressure is 0.2MPa, and the temperature is controlled to drop by 7℃ per minute until it reaches room temperature.

[0028] S7 finishing: The machining environment temperature is controlled at 20℃±1℃, and the machine tool is preheated for 10 minutes; the first pass cutting speed is 85m / min, the feed rate is 0.11mm / r, and a 0.2mm allowance is reserved on one side; the second reverse pass cutting speed is 125m / min, the feed rate is 0.05mm / r, and the final machining is completed.

[0029] Example 1: Comparison Table of Process Parameters and Accuracy Effects

[0030] Example 2: Medium-temperature short-time stress relief and high-proportion polyethylene glycol cooling scheme: This solution shortens the heat preservation time by increasing the stress relief temperature and enhances the slow cooling effect by increasing the proportion of polyethylene glycol. It is suitable for mass production scenarios and can shorten the overall processing cycle.

[0031] S1 reference preparation: The radial runout of the three-jaw chuck was measured to be 0.009 mm; the carbide grinding head was used to grind the center holes at both ends at a speed of 140 r / min, with a contact area of ​​88%.

[0032] S2 datum coaxiality test: The coaxiality error of the center holes at both ends measured by the coordinate measuring machine is 0.04mm, which meets the requirements.

[0033] S3 roughing: Rough turning of the outer diameter with a cutting speed of 65m / min, a feed rate of 0.22mm / r, and a single-sided machining allowance of 3.5mm.

[0034] S4 Deformation Control and Stress Relief: The maximum bending amount detected by the laser alignment instrument is 0.10mm; the straightness error after straightening is 0.045mm / m; the low-temperature stress relief annealing temperature is 250℃, the holding time is 2 hours, and the furnace is cooled; the axial machining allowance deviation is 0.18mm.

[0035] S5 Semi-finishing: Semi-finishing turning outer diameter cutting speed 75m / min, feed rate 0.16mm / r, with a 0.4mm finishing allowance on one side.

[0036] S6 Heat Treatment and Allowance Inspection: The allowance deviation of each section is 0.04mm; the pit furnace is heated to 580℃ and held for 2 hours; the atomized spray solution is a mixture of polyethylene glycol and water in a ratio of 1:2, the spray pressure is 0.3MPa, and the temperature is controlled to drop by 9℃ per minute.

[0037] S7 finishing: Preheat the machine tool for 10 minutes at a constant temperature of 20℃; first pass cutting speed 95m / min, feed rate 0.13mm / r, leave 0.2mm allowance; second reverse pass cutting speed 135m / min, feed rate 0.07mm / r.

[0038] Example 2: Comparison Table of Process Parameters and Accuracy Effects

[0039] Example 3: High-precision reference + high-speed finishing solution: This solution improves the surface quality and dimensional accuracy of the machined parts by optimizing the accuracy of the reference preparation and increasing the cutting speed of the finishing process. It is suitable for the finishing process of high-precision artillery barrels.

[0040] S1 reference preparation: The radial runout of the three-jaw chuck is strictly tested and controlled within 0.006mm; the carbide grinding head is finely ground at 120r / min to achieve a contact area of ​​90%.

[0041] S2 datum coaxiality test: The coaxiality error of the center holes at both ends measured by the coordinate measuring machine is 0.025mm.

[0042] S3 roughing: Rough turning of the outer diameter with a cutting speed of 60m / min, a feed rate of 0.20mm / r, and a machining allowance of 3mm on one side.

[0043] S4 Deformation Control and Stress Relief: The maximum bending amount detected by the laser alignment instrument is 0.08mm; the straightness error after straightening is 0.03mm / m; the low-temperature stress relief annealing temperature is 230℃, the holding time is 3 hours, and the furnace is cooled; the machining allowance deviation of each section is 0.10mm.

[0044] S5 Semi-finishing: Semi-finishing turning outer diameter cutting speed 70m / min, feed rate 0.15mm / r, with a 0.4mm finishing allowance on one side.

[0045] S6 Heat Treatment and Allowance Inspection: The allowance deviation of each section is 0.025mm; the pit furnace is heated to 550℃ and held for 2 hours; the atomized spray solution is a mixture of polyethylene glycol and water in a ratio of 1:3, the spray pressure is 0.25MPa, and the temperature is controlled to drop by 8℃ per minute.

[0046] S7 finishing: Preheat the machine tool for 10 minutes at a constant temperature of 20℃; first pass cutting speed 100m / min, feed rate 0.10mm / r, leave 0.2mm allowance; second reverse pass cutting speed 140m / min, feed rate 0.05mm / r.

[0047] Example 3: Comparison Table of Process Parameters and Accuracy Effects

[0048] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in the present invention, based on the technical solution and inventive concept of the present invention, should be covered within the scope of protection of the present invention.

Claims

1. A method for online control of coaxiality in CNC machining of tubes, characterized in that, The specific steps are as follows: S1. Prepare the raw material for the tube and machine the center holes at both ends; S2. Perform coaxiality testing on the center holes at both ends of the tube; S3. Rough machining of the tube, rough turning of the tube with a machining allowance reserved; S4. Inspect the bending deformation of the tube, straighten and relieve stress, and check whether the machining allowance is uniform. S5. Perform semi-finishing on the tube, leaving a 0.4mm finishing allowance; S6. Check whether the finishing allowance is uniform and perform heat treatment on the tube; S7. Finishing: After the machine tool has been preheated for 10 minutes in a constant temperature environment, perform the first pass. After the first pass, leave a machining allowance of 0.2mm. Perform the final machining with the second reverse pass.

2. The online coaxiality control process method for CNC machining of tubes according to claim 1, characterized in that, The contact area of ​​the center holes at both ends of S1 is greater than 80%, and the radial runout of the fixture is detected before processing.

3. The online coaxiality control process method for CNC machining of tubes according to claim 1, characterized in that, The S2 is inspected using a coordinate measuring machine, and the coaxiality error of the center holes at both ends is no greater than 0.05mm.

4. The online coaxiality control process method for CNC machining of tubes according to claim 1, characterized in that, The machining allowance for S3 is 2-4mm.

5. The online coaxiality control process method for CNC machining of tubes according to claim 1, characterized in that, The stress relief process in S4 employs a low-temperature stress relief annealing method, maintaining a temperature of 190-260 degrees Celsius for 2-4 hours.

6. The online coaxiality control process method for CNC machining of tubes according to claim 1, characterized in that, The S6 heat treatment involves maintaining the body temperature at 500-600 degrees Celsius for 2 hours, and using a mixture of polyethylene glycol solution and water to cool the body by spraying in an atomized manner, with a temperature difference of no more than 10 degrees Celsius per minute.

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