A precision machining process for metal parts

Abstract

The present application relates to the technical field of metal processing, and discloses a precision machining process for metal parts, comprising the following steps: S1, raw material selection and pretreatment; S2, rough machining and stress relief, based on the pretreatment blank size data of S1, cutting processing is carried out to obtain a rough machining part; then the rough machining part is heat treated, and after the effect of internal stress relief reaches the standard, a stress relief part is obtained; S3, semi-finishing and surface pretreatment; S4, precision grinding and finished product detection; S5, machine tool precision machining; S6, finished product post-processing. Through process linkage verification and closed loop detection, by clearly defining the implementation premise and feedback mechanism of each processing step, it is ensured that each process is based on the previous qualified workpiece, and the technical effects of controllable machining error and defect avoidance in advance are achieved. Compared with the prior art, the technical scheme directly connects each processing step and lacks premise verification, which solves the problem of unstable product quality caused by error accumulation and defect transmission.

Description

Technical Field

[0001] This invention relates to the field of metal processing technology, specifically to a precision machining process for metal parts. Background Technology

[0002] Precision metal parts are core components in aerospace, high-end equipment, and precision instruments. Their dimensional accuracy, surface quality, and structural stability directly determine the operational accuracy and service life of end-use equipment. These metal parts typically require multiple processing steps to form. The processing must balance material properties, processing efficiency, and finished product precision. It is a technology-intensive and critical processing link in modern manufacturing, demanding extremely high scientific rigor and precision in the processing technology.

[0003] In existing precision machining processes for metal parts, most solutions adopt a direct connection model between each machining step, lacking clear pre-implementation verification and closed-loop feedback mechanisms. Defects in preceding processes are not identified in a timely manner before proceeding to subsequent processes, leading to the continuous accumulation of errors and the propagation of defects. Ultimately, this results in large fluctuations in the dimensional accuracy of finished products and poor quality stability, making it difficult to meet the stringent requirements of high-end applications for precision metal parts. This machining mode, lacking coordinated verification, has become a core bottleneck restricting the improvement of the yield rate and quality stability of precision metal parts. Summary of the Invention

[0004] To address the shortcomings of existing technologies, this invention provides a precision machining process for metal parts, which solves the technical problems of direct connection between processing steps and lack of precondition verification in existing technologies, leading to error accumulation, defect transmission, and unstable finished product quality.

[0005] To achieve the above objectives, the present invention provides the following technical solution: a precision machining process for metal parts, comprising the following steps: S1, Raw material screening and pretreatment: Select metal billets that meet the preset composition requirements, conduct flaw detection and initial size calibration, and obtain pretreated billets when there are no internal defects and the initial size deviation is within the preset range. S2, Rough Machining and Stress Relief: Based on the pre-processed blank size data of S1, cutting is performed to obtain a rough-machined part; then the rough-machined part is heat-treated, and after the internal stress relief effect meets the standard, a stress-relieved part is obtained; S3, Semi-finishing and surface pretreatment: The stress-relief part is milled and bored to obtain a semi-finished part; then deburring, ultrasonic cleaning and drying are performed in sequence to obtain a clean workpiece; S4, Precision Grinding and Finished Product Inspection: The critical surfaces of the clean workpiece are ground using an ultrahard abrasive grinding wheel. Cooling and lubrication measures are taken during the grinding process to obtain the ground workpiece. Then, the dimensional accuracy, geometric tolerances and surface quality are inspected by special inspection equipment. If they pass the inspection, the workpiece proceeds to the next step; otherwise, it is returned to this step for re-grinding. S5, Precision machining: Boring is performed on the ground workpiece using a boring machine; S6, Post-processing of finished products: Rust prevention treatment and sealing packaging are carried out on the qualified workpieces to obtain finished metal parts.

[0006] Preferably, the boring machine includes a frame, a boring assembly is provided on the side wall of the frame, a mounting bracket is fixedly connected to the side wall of the frame, and a fixing assembly is provided on the side wall of the mounting bracket, the fixing assembly including: A fixing rod, wherein a fixing plate is fixedly connected to the end face of the fixing rod, and bolts are threadedly connected to the side wall of the fixing plate; Movable plate one, a connecting rod is fixedly connected to the side wall of movable plate one, a limit plate is sleeved on the side wall of the connecting rod, and movable plate two is sleeved on the side wall of the fixed rod; A sliding frame, wherein a cam is rotatably connected to the side wall of the sliding frame.

[0007] The boring assembly includes a drive motor fixedly connected to the side wall of the frame, a bidirectional screw fixedly connected to the output end of the drive motor, a mounting base threadedly connected to the side wall of the bidirectional screw, and a boring device fixedly connected to the side wall of the mounting base. The fixing rod is fixedly connected to the side wall of the mounting frame, and the end face of the bolt is fixedly connected to a knob. The bolt is rotatably connected to the limiting plate. Rotating the bolt changes the lateral position of the limiting plate. The side wall of the connecting rod is fitted with a spring, and the number of springs is set in several groups. The spring abuts against the sliding frame, the spring abuts against the movable plate, and the spring abuts against the limiting plate. The spring pushes the sliding frame to the center.

[0008] The sliding frame is sleeved with the connecting rod, the cam is movably connected to the movable plate, and the cam is movably connected to the fixed plate. A handle is fixedly connected to the outer wall of the cam, and the movable plate is sleeved with the fixed rod; The side walls of movable plate one and movable plate two are fixedly connected to a hinge frame. An arc-shaped block is hinged to the end face of the hinge frame. A torsion spring is sleeved on the side wall of the arc-shaped block. One end of the torsion spring abuts against the hinge frame, and the other end of the torsion spring abuts against the arc-shaped block.

[0009] Preferably, in step S1, the flaw detection is performed using ultrasonic testing, and the metal billet is any one of stainless steel, aluminum alloy, or titanium alloy, with an initial dimensional deviation ≤ ±0.5 mm.

[0010] Preferably, in step S2, the cutting process uses a CNC cutting machine with a cutting speed of 80-120 m / min and a feed rate of 0.1-0.3 mm / r, and the dimensional tolerance of the rough-machined part is controlled within ±0.1-0.3 mm.

[0011] Preferably, in step S2, the heat treatment is vacuum heat treatment, the treatment temperature is 850-950℃, the holding time is 2-4h, the cooling rate is ≤50℃ / h, and the internal stress relief rate is ≥90%.

[0012] Preferably, in step S3, the milling speed is 100-150 m / min, the coaxiality error of the boring is ≤0.01 mm, the surface roughness Ra of the semi-finished part is ≤1.6 μm, and a fine grinding allowance of 0.05-0.1 mm is reserved.

[0013] Preferably, in step S3, ultrasonic cleaning uses deionized water as the medium, the cleaning temperature is 40-60℃, and the cleaning time is 10-20 minutes. The drying process is hot air drying, with a drying temperature of 80-120℃ and a drying time of 30-60 minutes.

[0014] Preferably, in step S4, the superhard abrasive wheel is a cubic boron nitride wheel or a diamond wheel, the grinding speed is 30-50 m / s, the grinding depth is 0.001-0.003 mm / cycle, and the cooling and lubrication measures are oil-based cutting fluid.

[0015] Preferably, in step S4, the dimensional tolerance of the workpiece being ground is ≤ ±0.005 mm, and the surface roughness Ra is ≤ 0.2 μm; The number of regrinding operations is ≤2 times. Specialized testing equipment includes a coordinate measuring machine, a laser interferometer, and a surface roughness tester.

[0016] Preferably, in step S6, the rust prevention treatment is passivation or coating with rust-preventive oil; The passivation treatment time is 15-30 min, and the anti-rust oil coating thickness is 5-10 μm.

[0017] Preferably, S2 uses the pre-treated blank from S1 as the sole processing reference; S3 takes the achievement of the internal stress relief rate of S2 as the sole prerequisite for implementation; S4 is executed under the condition that the fine grinding allowance of S3 meets the requirements and the clean workpiece is free of burrs and oil residue. If the re-grinding in S4 fails after more than 2 cycles, return to S3 for semi-finishing, and adjust the finishing allowance after the semi-finishing to 0.08-0.12mm.

[0018] This invention provides a precision machining process for metal parts. It has the following beneficial effects: 1. This invention adopts process linkage verification and closed-loop detection, and by clarifying the implementation prerequisites and feedback mechanisms of each processing step, it ensures that each process is carried out based on the qualified workpiece in the previous process, and achieves the technical effect of controllable processing error and early avoidance of defects. Compared with the existing technology where each processing step is directly connected and there is no prerequisite verification, this invention solves the shortcomings of error accumulation and defect transmission that lead to unstable finished product quality.

[0019] 2. This invention adopts a combination of vacuum heat treatment, superhard abrasive grinding wheel and special cooling and lubrication, combined with the design concept of precise adaptation to material characteristics, to achieve the technical effect of full release of internal stress in metal parts, excellent surface quality and strong structural stability. Compared with the technical solutions of the prior art that use ordinary heat treatment, general grinding wheel or single cooling method, it solves the problem of deformation caused by residual internal stress and easy burning or scratches on the surface.

[0020] 3. This invention adopts optimized process logic and scenario-based process adjustment. By rationally planning the processing sequence and customizing process details for different usage scenarios, it achieves the technical effect of wide processing adaptability and strong adaptability of finished product working conditions. Compared with the existing technology, which has a fixed and chaotic process sequence and lacks scenario-specific design, this invention solves the shortcomings of the existing technology, such as easy generation of secondary pollution and difficulty in meeting the needs of special working conditions.

[0021] 4. The boring machine of this invention, through the setting of fixed components, allows movable plate one and movable plate two to move towards each other, thereby achieving fixed clamping of the workpiece. The workpiece is clamped simultaneously from both sides, with uniform clamping force, preventing offset or tilting, and ensuring processing accuracy. The cam has a self-locking characteristic and will not easily reverse after being rotated to the positioning position. When boring a workpiece on one side is required, the workpiece is offset and placed closer to one side of one of the boring devices. Rotating the bolt changes the lateral position of the limiting plate and changes the initial distance between the movable plates. Regardless of the size of the workpiece, the clamping space can be flexibly adjusted, improving the applicability of the equipment. After adjustment, movable plate one and movable plate two can fit more closely to both sides of the workpiece, reducing gaps, ensuring accurate workpiece positioning, uniform clamping force, and avoiding workpiece offset due to excessive or insufficient distance. Attached Figure Description

[0022] Figure 1 This is a schematic diagram of the process of the present invention; Figure 2 This is a schematic diagram of the main structure of the present invention; Figure 3For the present invention Figure 2 Schematic diagram of the structure of region A in the middle; Figure 4 This is a schematic diagram of the fixed component structure of the present invention; Figure 5 This is a schematic diagram of the structure of the movable plate of the present invention; Figure 6 For the present invention Figure 5 Schematic diagram of the structure of region B in the middle. Detailed Implementation

[0023] The technical solution of the present invention will now be clearly and completely described with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention. Example

[0024] Please see the appendix Figure 1 This invention provides a precision machining process for metal parts, including the following steps: S1, Raw material screening and pretreatment: Select metal billets that meet the preset composition requirements, conduct flaw detection and initial size calibration, and obtain pretreated billets when there are no internal defects and the initial size deviation is within the preset range. Among them, ultrasonic testing is used for flaw detection, and the metal billet can be any one of stainless steel, aluminum alloy or titanium alloy, with an initial dimensional deviation of ≤±0.5mm. S2, Rough Machining and Stress Relief: Based on the pre-processed blank size data of S1, cutting is performed to obtain a rough-machined part; then the rough-machined part is heat-treated, and after the internal stress relief effect meets the standard, a stress-relieved part is obtained; The cutting process uses CNC cutting equipment with a cutting speed of 80-120 m / min and a feed rate of 0.1-0.3 mm / r. The dimensional tolerance of the rough-machined parts is controlled within ±0.1-0.3 mm. The heat treatment is vacuum heat treatment, with a treatment temperature of 850-950℃, a holding time of 2-4 hours, a cooling rate of ≤50℃ / h, and an internal stress relief rate of ≥90%. S3, Semi-finishing and surface pretreatment: The stress-relief part is milled and bored to obtain a semi-finished part; then deburring, ultrasonic cleaning and drying are performed in sequence to obtain a clean workpiece; Among them, the milling speed is 100-150m / min, the coaxiality error of the boring is ≤0.01mm, the surface roughness Ra of the semi-finished part is ≤1.6μm, and a fine grinding allowance of 0.05-0.1mm is reserved; Ultrasonic cleaning uses deionized water as the medium, with a cleaning temperature of 40-60℃ and a cleaning time of 10-20 minutes. The drying process is hot air drying, with a drying temperature of 80-120℃ and a drying time of 30-60 minutes; S4, Precision Grinding and Finished Product Inspection: The critical surfaces of the clean workpiece are ground using an ultrahard abrasive grinding wheel. Cooling and lubrication measures are taken during the grinding process to obtain the ground workpiece. Then, the dimensional accuracy, geometric tolerances and surface quality are inspected by special inspection equipment. If they pass the inspection, the workpiece proceeds to the next step; otherwise, it is returned to this step for re-grinding. Among them, the superhard abrasive grinding wheel is a cubic boron nitride grinding wheel or a diamond grinding wheel, the grinding speed is 30-50m / s, the grinding depth is 0.001-0.003mm / time, and the cooling and lubrication measures are oil-based cutting fluid; The dimensional tolerance of the ground workpiece is ≤ ±0.005 mm, and the surface roughness Ra is ≤ 0.2 μm; The number of regrinding operations is ≤2 times. Specialized testing equipment includes a coordinate measuring machine, a laser interferometer, and a surface roughness tester. S5, Precision machining: Boring is performed on the ground workpiece using a boring machine; The boring machine includes a frame 1, a boring assembly is provided on the side wall of the frame 1, a mounting frame 6 is fixedly connected to the side wall of the frame 1, and a fixing assembly 7 is provided on the side wall of the mounting frame 6. The fixing assembly 7 includes a fixing rod 701, a first movable plate 702, a connecting rod 703, a limiting plate 704, a second movable plate 705, a fixing plate 706, a bolt 707, a sliding frame 708, a spring 709, and a cam 710. In one embodiment, the fixing rod 701 is fixedly connected to the side wall of the mounting bracket 6, and the end face of the fixing rod 701 is fixedly connected to the fixing plate 706. The side wall of the fixing plate 706 is threadedly connected to the bolt 707, and the end face of the bolt 707 is fixedly connected to the knob. Movable plate 702 is sleeved with fixed rod 701. A connecting rod 703 is fixedly connected to the side wall of movable plate 702. A limiting plate 704 is sleeved on the side wall of connecting rod 703. Bolt 707 is rotatably connected to limiting plate 704. Rotating bolt 707 changes the lateral position of limiting plate 704. Movable plate 705 is sleeved on the side wall of fixed rod 701. Spring 709 is sleeved on the side wall of connecting rod 703. Several sets of spring 709 are provided. Spring 709 abuts against sliding frame 708, spring 709 abuts against movable plate 705, and spring 709 abuts against limiting plate 704. Spring 709 pushes sliding frame 708 to center.

[0025] The sliding frame 708 is sleeved with the connecting rod 703. The side wall of the sliding frame 708 is rotatably connected to the cam 710. The cam 710 is movably connected to the movable plate 705 and the fixed plate 706. The outer wall of the cam 710 is fixedly connected to the handle.

[0026] The boring assembly includes a drive motor 2 fixedly connected to the side wall of the frame 1. A bidirectional screw 3 is fixedly connected to the output end of the drive motor 2. A mounting base 4 is threadedly connected to the side wall of the bidirectional screw 3. A boring device 5 is fixedly connected to the side wall of the mounting base 4. The boring device 5 includes a boring bar and a boring tool. The specific structure and principle of the boring bar and boring tool are common in existing technologies and will not be described in detail here. Figure 3 This is also reflected in [the text].

[0027] The workpiece is placed between movable plate 1 702 and movable plate 2 705. The cam 710 is rotated, causing it to push movable plate 2 705 and limit plate 704. Limit plate 704 moves towards the fixed plate 706, and further drives movable plate 1 702 to move through connecting rod 703. Movable plate 1 702 and movable plate 2 705 move towards each other, thus achieving fixed clamping of the workpiece. The workpiece is clamped from both sides simultaneously, with uniform clamping force, without deviation or tilting, ensuring machining accuracy. The cam 710 has a self-locking characteristic and will not easily reverse after being rotated to the positioning position.

[0028] The boring device 5 is set in two sets, which can simultaneously bore both sides of the workpiece. When it is necessary to bore only one side of the workpiece, the workpiece is offset and placed close to one side of one set of boring devices 5. After the workpiece is clamped, the bidirectional screw 3 can be driven by the drive motor 2 to rotate, so that the mounting base 4 and the boring device 5 move laterally, and the boring device 5 bores the workpiece.

[0029] Rotating bolt 707 changes the lateral position of limit plate 704. At this time, the distance between movable plate 1 702 and movable plate 2 705 is reduced, changing the initial distance between the movable plates. Regardless of the size of the workpiece, the clamping space can be flexibly adjusted, improving the applicability of the equipment. After adjustment, movable plate 1 702 and movable plate 2 705 can fit more closely to both sides of the workpiece, reducing gaps, ensuring accurate workpiece positioning, uniform clamping force, and avoiding workpiece displacement due to excessive or insufficient distance.

[0030] In addition, a hinge frame 8 is fixedly connected to the side wall of movable plate 1 702 and movable plate 2 705. An arc-shaped block 9 is hinged to the end face of the hinge frame 8. A torsion spring 10 is sleeved on the side wall of the arc-shaped block 9. One end of the torsion spring 10 abuts against the hinge frame 8, and the other end of the torsion spring 10 abuts against the arc-shaped block 9. The arc-shaped block 9 rotates along the outer surface of the workpiece, so that the arc-shaped block 9 fits against the outer surface of the workpiece. Even if the outer surface of the workpiece has a certain curvature, the arc-shaped block 9 can automatically fit, adapting to workpieces of different shapes and sizes, with strong versatility and improved clamping effect. The arc-shaped block 9 is close to the outer surface of the workpiece, with a large contact area and more uniform force, making it less likely for the workpiece to loosen or slip during processing, thus enhancing clamping stability. After releasing the clamp, the operator does not need to repeatedly adjust the clamping angle or position, as the arc-shaped block 9 can automatically align under the action of the torsion spring 10.

[0031] In use, the workpiece is placed between movable plate 1 702 and movable plate 2 705. The cam 710 is rotated, causing the cam 710 to push movable plate 2 705 and the limiting plate 704. The limiting plate 704 moves towards the fixed plate 706, and further drives movable plate 1 702 to move in the same direction through the connecting rod 703. Movable plate 1 702 and movable plate 2 705 move towards each other, thus fixing and clamping the workpiece. The workpiece is then offset and placed closer to one side of one of the boring devices 5. After clamping the workpiece, the bidirectional screw 3 can be driven to rotate by the drive motor 2, causing the mounting base 4 and the boring device 5 to move laterally. The boring device 5 then bores the workpiece.

[0032] S6, Post-processing of finished products: Rust prevention treatment and sealed packaging are carried out on the qualified ground workpieces to obtain finished metal parts; Among them, rust prevention treatment includes passivation treatment or coating with rust-preventive oil; The passivation treatment time is 15-30 min, and the anti-rust oil coating thickness is 5-10 μm.

[0033] S2 uses the pre-treated blank of S1 as the sole processing reference; S3 takes the achievement of the internal stress relief rate of S2 as the sole prerequisite for implementation; S4 is executed under the condition that the fine grinding allowance of S3 meets the requirements and the clean workpiece is free of burrs and oil residue. If the re-grinding in S4 fails after more than 2 cycles, return to S3 for semi-finishing, and adjust the finishing allowance after the semi-finishing to 0.08-0.12mm.

[0034] The following is a description with reference to specific embodiments: Example

[0035] A precision machining process for metal parts includes the following steps: S1: Raw material screening and pretreatment: Select aluminum alloy billets, use ultrasonic flaw detection to detect no internal defects, initial size deviation ±0.1mm, and obtain pretreated billets; S2: Rough machining and stress relief: Using the pre-treated blank from S1 as the sole machining reference, CNC milling machine is used for cutting at a cutting speed of 80m / min and a feed rate of 0.1mm / r. The dimensional tolerance of the rough-machined part is ±0.1mm. Subsequently, vacuum heat treatment is performed at a temperature of 850℃, a holding time of 2h, and a cooling rate of 30℃ / h. The internal stress relief rate is tested to be 90%, resulting in a stress-relieved part. S3: Semi-finishing and surface pretreatment are based solely on the premise that the internal stress relief rate of S2 meets the standard. The stress-relieved part is CNC milled at a speed of 100m / min and bored. The coaxiality error is 0.01mm. The surface roughness after machining is Ra1.6μm. A fine grinding allowance of 0.05mm is reserved to obtain a semi-finished part. Then, mechanical deburring, ultrasonic cleaning with deionized water as the medium at 40℃ for 10min, and hot air drying at 80℃ for 30min are performed in sequence to obtain a clean workpiece without burrs and oil residue. S4: Precision grinding and finished product inspection are performed under the condition that the fine grinding allowance in S3 meets the requirements and the clean workpiece is free of impurities. A diamond grinding wheel is used to grind the key surfaces of the clean workpiece at a grinding speed of 30 m / s and a grinding depth of 0.001 mm / cycle. Oil-based cutting fluid is used for cooling and lubrication during the grinding process. After machining, the workpiece dimensional tolerance is ±0.005 mm and the surface roughness Ra is 0.2 μm. The workpiece is inspected using a coordinate measuring machine, laser interferometer, and surface roughness tester. All indicators are qualified, and no re-grinding is required. The number of re-grinding cycles will not exceed 2. S5: Use the aforementioned boring machine to perform boring operations on the ground workpiece; S6: Finished product post-processing. The qualified ground workpieces are subjected to rust prevention treatment by applying rust-preventive oil with a coating thickness of 5μm. Then, they are sealed and packaged to obtain the finished aluminum alloy precision connector. Example

[0036] A precision machining process for metal parts includes the following steps: S1: Raw material screening and pretreatment: Select stainless steel 304 billet, use ultrasonic flaw detection to find no internal defects, initial size deviation ±0.3mm, to obtain pretreated billet; S2: Rough machining and stress relief. Using the pre-treated blank from S1 as the sole machining reference, a machining center was used for cutting at a cutting speed of 100 m / min and a feed rate of 0.2 mm / r. The dimensional tolerance of the rough-machined part was ±0.2 mm. Subsequently, vacuum heat treatment was performed at a temperature of 900℃, a holding time of 3 h, and a cooling rate of 40℃ / h. The internal stress relief rate was found to be 95%, resulting in a stress-relieved part. S3: Semi-finishing and surface pretreatment are based solely on the premise that the internal stress relief rate of S2 meets the standard. The stress-relieved part is CNC milled at a speed of 120m / min and bored, with a coaxiality error of 0.008mm. The surface roughness after machining is Ra1.2μm, with a fine grinding allowance of 0.08mm, to obtain a semi-finished part. Then, mechanical deburring, ultrasonic cleaning with deionized water as the medium at 50℃ for 15min, and hot air drying at 100℃ for 40min are performed in sequence to obtain a clean workpiece without burrs and oil residue. S4: Precision grinding and finished product inspection are performed under the condition that the finishing allowance in S3 meets the requirements and the clean workpiece is free of impurities. A cubic boron nitride grinding wheel is used to grind the key surfaces of the clean workpiece at a grinding speed of 40 m / s and a grinding depth of 0.002 mm / cycle. Oil-based cutting fluid is used for cooling and lubrication during the grinding process. After machining, the workpiece dimensional tolerance is ±0.003 mm and the surface roughness Ra is 0.15 μm. Inspection using a coordinate measuring machine, laser interferometer, and surface roughness tester shows excellent performance in all indicators, and no re-grinding is required. S5: Use the aforementioned boring machine to perform boring operations on the ground workpiece; S6: Post-processing of finished products involves rust prevention treatment of the qualified ground workpieces using a passivation process for 20 minutes. The workpieces are then sealed and packaged to obtain finished stainless steel 304 precision shaft parts. Example

[0037] A precision machining process for metal parts includes the following steps: S1: Raw material screening and pretreatment: Select titanium alloy billets, use ultrasonic flaw detection to detect no internal defects, initial size deviation ±0.5mm, and obtain pretreated billets; S2: Rough machining and stress relief: Using the pre-treated blank from S1 as the sole machining reference, a machining center was used for cutting at a cutting speed of 120 m / min and a feed rate of 0.3 mm / r. The dimensional tolerance of the rough-machined part was ±0.3 mm. Subsequently, vacuum heat treatment was performed at a temperature of 950℃, a holding time of 4 h, and a cooling rate of 50℃ / h. The internal stress relief rate was found to be 90%, resulting in a stress-relieved part. S3: Semi-finishing and surface pretreatment are based solely on the premise that the internal stress relief rate of S2 meets the standard. The stress-relieved part is CNC milled at a speed of 150m / min and bored, with a coaxiality error of 0.01mm. The surface roughness after machining is Ra1.6μm, with a fine grinding allowance of 0.1mm, to obtain a semi-finished part. Then, mechanical deburring, ultrasonic cleaning with deionized water as the medium at 60℃ for 20min, and hot air drying at 120℃ for 60min are performed in sequence to obtain a clean workpiece without burrs and oil residue. S4: Precision grinding and finished product inspection are performed under the condition that the fine grinding allowance in S3 meets the requirements and the clean workpiece is free of impurities. A diamond grinding wheel is used to grind the key surfaces of the clean workpiece at a grinding speed of 50 m / s and a grinding depth of 0.003 mm / cycle. Oil-based cutting fluid is used for cooling and lubrication during the grinding process. After machining, the workpiece dimensional tolerance is ±0.005 mm and the surface roughness Ra is 0.2 μm. The workpiece is inspected using a coordinate measuring machine, laser interferometer, and surface roughness tester. All indicators are qualified, and no re-grinding is required. The number of re-grinding cycles will not exceed 2. S5: Use the aforementioned boring machine to perform boring operations on the ground workpiece; S6: Finished product post-processing. The qualified ground workpieces are subjected to rust prevention treatment by coating with rust-preventive oil with a coating thickness of 10μm. Then, they are sealed and packaged to obtain finished titanium alloy precision structural parts. Example

[0038] A precision machining process for metal parts includes the following steps: S1: Raw material screening and pretreatment. Hastelloy C-276 billet was selected and ultrasonic testing was used to detect no internal defects. The initial dimensional deviation was ±0.4mm, and the pretreated billet was obtained. S2: Rough machining and stress relief. Using the pre-treated blank from S1 as the sole machining reference, a machining center was used for cutting at a cutting speed of 90 m / min and a feed rate of 0.15 mm / r. The dimensional tolerance of the rough-machined part was ±0.2 mm. Subsequently, vacuum heat treatment was performed at a temperature of 920℃, a holding time of 3.5 h, and a cooling rate of 35℃ / h. The internal stress relief rate was found to be 94%, resulting in a stress-relieved part. S3: Semi-finishing and surface pretreatment are based solely on the premise that the internal stress relief rate of S2 meets the standard. The stress-relieved part is CNC milled at a speed of 130m / min and bored. The coaxiality error is 0.009mm, and the surface roughness after machining is Ra1.4μm. A fine grinding allowance of 0.07mm is reserved to obtain a semi-finished part. Then, mechanical deburring, ultrasonic cleaning with deionized water as the medium at 55℃ for 18min, and hot air drying at 110℃ for 50min are performed in sequence to obtain a clean workpiece without burrs and oil residue. S4: Precision grinding and finished product inspection are performed under the condition that the fine grinding allowance in S3 meets the requirements and the clean workpiece is free of impurities. A diamond grinding wheel is used to grind the key surfaces of the clean workpiece at a grinding speed of 45 m / s and a grinding depth of 0.0025 mm / cycle. A special corrosion-resistant cutting fluid is used for cooling and lubrication during the grinding process. After machining, the workpiece's dimensional tolerance is ±0.004 mm and the surface roughness Ra is 0.18 μm. Inspection using a coordinate measuring machine, laser interferometer, and roughness tester revealed that the initial dimensional and positional tolerances were slightly out of tolerance. After one re-grinding, the workpiece passed inspection, and the number of re-grinding cycles did not exceed two. S5: Use the aforementioned boring machine to perform boring operations on the ground workpiece; S6: Finished product post-processing. The qualified ground workpieces are subjected to double anti-rust treatment. First, they are passivated for 25 minutes, then coated with 8μm special corrosion-resistant and anti-rust oil, and then sealed and moisture-proof packaging is used to obtain the finished Hastelloy precision chemical parts.

[0039] Comparative Example 1 Based on the steps of Example 2, the vacuum heat treatment step in S2 roughing and stress relief is omitted. After roughing, the process proceeds directly to semi-finishing, and the remaining steps are the same as in Example 2.

[0040] Comparative Example 2 Based on the steps of Example 2, surface pretreatment is performed in S3 before semi-finishing, that is, cleaning and drying are performed before milling and boring. The remaining steps are the same as in Example 2.

[0041] Comparative Example 3 Based on the steps of Example 2, the superhard abrasive grinding wheel and oil-based cutting fluid cooling in S4 are replaced with ordinary white corundum grinding wheel and dry grinding, and the remaining steps are the same as in Example 2.

[0042] Comparative Example 4 Based on the steps of Example 2, each step is directly connected without precondition verification, and the remaining steps are consistent with Example 2.

[0043] Table 1 Performance Index Data Table Combining Examples 1-4 and Comparative Examples 1-4 with the performance index data table, it can be seen that the key influencing factors in this invention have a significant impact on the dimensional accuracy, surface quality, structural stability, and finished product qualification rate of the metal parts, and that there is a good synergistic effect among the factors, as detailed below: Comparative Example 1, by omitting the core stress elimination vacuum heat treatment step, failed to effectively release the internal stress generated during rough machining, leading to accumulated deformation in subsequent processing. Comparative Example 2, by reversing the process order of semi-finishing and surface pretreatment, prevented the complete removal of burrs and oil stains generated during semi-finishing, contaminating subsequent grinding processes. Comparative Example 3, by replacing the core grinding combination of superhard abrasive grinding wheel and oil-based cutting fluid with ordinary white corundum grinding wheel and dry grinding, lost the hardness support and heat dissipation capacity required for high-precision grinding. Comparative Example 4, by canceling the step linkage precondition verification, caused defects in the preceding process to be directly transmitted to subsequent steps, increasing the cumulative error. All four of these factors significantly reduced the overall machining performance of metal parts. In contrast, the embodiments optimized process logic, precisely controlled process parameters, matched the compatibility of materials and processing methods, and Example 4 specifically designed a dedicated process scheme for high corrosion resistance scenarios, achieving a synergistic improvement in the conventional machining accuracy of metal parts and the needs of special application scenarios.

[0044] In the examples, the dimensional tolerance of the metal parts is between ±0.003mm and ±0.005mm, the surface roughness Ra is between 0.15μm and 0.2μm, and the finished product qualification rate is between 92% and 98%. Among them, the specific scenario type of Example 4 also has high corrosion resistance. Examples 1-4 all have controllable error caused by step linkage, which is significantly better than the comparative examples.

[0045] Example 2 demonstrates the best performance in general scenarios, with a dimensional tolerance of ±0.003mm, a surface roughness of Ra0.15μm, and a pass rate of 98%, exhibiting balanced overall performance. Example 4 excels in high corrosion resistance scenarios, with a dimensional tolerance of ±0.004mm, a Staphylococcus aureus inhibition rate of 99.6%, and meets corrosion resistance standards, making it suitable for chemical corrosion environments. Both examples respectively cover the optimal requirements for general precision machining and special-condition machining.

[0046] From the perspective of the overall processing performance of metal parts, all performance indicators in the example are significantly higher than those in the comparative example, mainly due to the synergistic effect of various key factors: The process logic and step linkage conditions in Examples 1-4 are precisely matched with the needs of error accumulation control and early defect avoidance in metal processing. The process connection and parameter combination in Example 2 effectively control the errors of each link. Through the detection and confirmation of the coordinate measuring machine and laser interferometer, the form and position tolerance fluctuation range is ≤0.002mm. An integrated processing system with unified benchmark, stress release, progressive accuracy and closed-loop detection is formed. The balanced performance of dimensional tolerance ±0.003mm, surface roughness Ra0.15μm and pass rate of 98% is due to this. Example 4 specifically adjusts the cutting fluid to a special corrosion-resistant type and the post-treatment to a double anti-rust solution to enhance corrosion resistance. At the same time, the grinding parameters are optimized to balance accuracy and corrosion resistance, and finally meet the stringent use requirements of chemical equipment parts.

[0047] The deep synergy between core process combinations and material properties in the embodiments: In Example 2, vacuum heat treatment is compatible with the material properties of stainless steel 304, achieving a 95% internal stress relief rate and effectively preventing deformation during subsequent processing; the combination of superhard abrasive cubic boron nitride grinding wheels and oil-based cutting fluid ensures uniform heat dissipation during grinding, preventing surface burns. Combined with a milling speed of 120 m / min and a fine grinding allowance of 0.08 mm, a balance between high precision and high efficiency is achieved; In Comparative Example 1, due to the omission of vacuum heat treatment, residual internal stress led to a deformation rate of 45%; In Comparative Example 3, due to the replacement of the grinding process, the incidence of surface burns and scratches reached 25%; In Comparative Example 4, due to the cancellation of linkage verification, 12% of the workpieces showed grinding defects due to substandard pre-process cleanliness, further highlighting the necessity of synergy between core process combinations and process logic.

[0048] Comparative Example 1, by omitting the vacuum heat treatment step, failed to create a channel for internal stress release, resulting in a dimensional tolerance of only ±0.012 mm, four times larger than that of Example 2. The surface roughness Ra was 0.45 μm, and obvious grinding cracks appeared, leading to a pass rate of only 62% and a significant decrease in the structural stability of the metal part. Comparative Example 2, by reversing the order of semi-finishing and surface pretreatment, failed to completely remove new burrs and oil stains generated during semi-finishing, increasing the bore coaxiality error to 0.018 mm. The surface roughness Ra was 0.32 μm, and the pass rate was 81%, undermining the foundation for precision grinding. The conditions were disrupted; Comparative Example 3 was replaced with ordinary white corundum grinding wheel + dry grinding. The excessive temperature during the grinding process caused surface deterioration, with a dimensional tolerance of ±0.009mm, a surface burn rate of 30%, and a pass rate of 75%, which could not meet the precision and surface quality requirements of precision machining; Comparative Example 4 was affected by the cancellation of step linkage verification. Defects such as substandard internal stress in the preceding step and insufficient fine grinding allowance were directly transmitted. 12% of the workpieces showed over-grinding or residual oil stains, with a dimensional tolerance of ±0.007mm and a pass rate of 83%. The failure of the process closed loop led to a decline in overall performance.

[0049] Example 1, with a dimensional tolerance of ±0.005mm and a pass rate of 92%, meets basic precision requirements but offers moderate efficiency, making it suitable for cost-sensitive scenarios with moderate precision requirements. Example 3, using the upper limit of parameters, achieves a dimensional tolerance of ±0.005mm and a pass rate of 93%, resulting in higher processing efficiency and making it suitable for heavy-duty precision equipment scenarios with large processing allowances. Example 4, while having slightly lower conventional precision than Example 2, boasts outstanding corrosion resistance and adaptability to special working conditions, precisely meeting the needs of highly corrosive environments such as chemical and marine engineering. Examples 1-4, by maintaining core process logic and linkage verification, all achieve controllable errors, further demonstrating the scenario adaptability flexibility of the present invention.

[0050] In summary, the key factors in this invention—process logic design, core process combination, parameter and material adaptation, and scenario-specific adjustments—work together synergistically to enable the precision machining process for metal parts to meet the high precision and high stability requirements of general scenarios, as well as the special requirements of high corrosion resistance, heavy-duty machining, and cost-sensitive scenarios. Furthermore, through comparative examples 1-4, the irreplaceable nature of stress-relief vacuum heat treatment, rational process sequence, combination of superhard abrasive grinding wheel and oil-based cutting fluid, and step-by-step linkage verification are verified, ultimately achieving the optimal balance of dimensional accuracy, surface quality, structural stability, and working condition adaptability under different application scenarios.

[0051] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A precision machining process for metal parts, characterized in that, Includes the following steps: S1, Raw material screening and pretreatment: Select metal billets that meet the preset composition requirements, conduct flaw detection and initial size calibration, and obtain pretreated billets when there are no internal defects and the initial size deviation is within the preset range. S2, Rough Machining and Stress Relief: Based on the pre-processed blank size data of S1, cutting is performed to obtain a rough-machined part; then the rough-machined part is heat-treated, and after the internal stress relief effect meets the standard, a stress-relieved part is obtained; S3, Semi-finishing and surface pretreatment: The stress-relief part is milled and bored to obtain a semi-finished part; then deburring, ultrasonic cleaning and drying are performed in sequence to obtain a clean workpiece; S4, Precision Grinding and Finished Product Inspection: The critical surfaces of the clean workpiece are ground using an ultrahard abrasive grinding wheel. Cooling and lubrication measures are taken during the grinding process to obtain the ground workpiece. Then, the dimensional accuracy, geometric tolerances and surface quality are inspected by special inspection equipment. If they pass the inspection, the workpiece proceeds to the next step; otherwise, it is returned to this step for re-grinding. S5, Precision machining: Boring is performed on the ground workpiece using a boring machine; S6, Post-processing of finished products: Rust prevention treatment and sealing packaging are carried out on the qualified workpieces to obtain finished metal parts; S2 uses the pre-treated blank from S1 as the sole processing reference. S3 takes the achievement of the internal stress relief rate of S2 as the sole prerequisite for implementation; S4 is executed under the condition that the fine grinding allowance of S3 meets the requirements and the clean workpiece is free of burrs and oil residue. If the re-grinding in S4 fails after more than 2 times, return to S3 for semi-finishing again, and adjust the finishing allowance after the semi-finishing to 0.08-0.12mm. The boring machine includes a frame (1), a boring assembly is provided on the side wall of the frame (1), a mounting bracket (6) is fixedly connected to the side wall of the frame (1), and a fixing assembly (7) is provided on the side wall of the mounting bracket (6). The fixing assembly (7) includes: A fixing rod (701) is fixedly connected to a fixing plate (706) on its end face, and a bolt (707) is threadedly connected to the side wall of the fixing plate (706). Movable plate one (702), a connecting rod (703) is fixedly connected to the side wall of the movable plate one (702), a limit plate (704) is sleeved on the side wall of the connecting rod (703), and a movable plate two (705) is sleeved on the side wall of the fixed rod (701). A sliding frame (708) has a cam (710) rotatably connected to its side wall. The boring assembly includes a drive motor (2) fixedly connected to the side wall of the frame (1), the output end of the drive motor (2) is fixedly connected to a bidirectional screw (3), the side wall of the bidirectional screw (3) is threadedly connected to a mounting base (4), and the side wall of the mounting base (4) is fixedly connected to a boring device (5). The fixing rod (701) is fixedly connected to the side wall of the mounting bracket (6), and the end face of the bolt (707) is fixedly connected to a knob; The side wall of the connecting rod (703) is fitted with a spring (709), and the number of springs (709) is set in several groups. The spring (709) abuts against the sliding frame (708), the spring (709) abuts against the movable plate (705), and the spring (709) abuts against the limiting plate (704). The sliding frame (708) is sleeved with the connecting rod (703), the cam (710) is movably connected with the movable plate (705), and the cam (710) is movably connected with the fixed plate (706); A handle is fixedly connected to the outer wall of the cam (710), and the movable plate (702) is sleeved with the fixed rod (701); The side walls of the first movable plate (702) and the second movable plate (705) are fixedly connected to a hinge frame (8). An arc-shaped block (9) is hinged to the end face of the hinge frame (8). A torsion spring (10) is sleeved on the side wall of the arc-shaped block (9). One end of the torsion spring (10) abuts against the hinge frame (8), and the other end of the torsion spring (10) abuts against the arc-shaped block (9).

2. The precision machining process for metal parts according to claim 1, characterized in that: In step S1, ultrasonic testing is used for flaw detection. The metal billet is any one of stainless steel, aluminum alloy, or titanium alloy, and the initial dimensional deviation is ≤ ±0.5 mm.

3. The precision machining process for metal parts according to claim 1, characterized in that: In S2, the cutting process uses CNC cutting equipment with a cutting speed of 80-120 m / min and a feed rate of 0.1-0.3 mm / r. The dimensional tolerance of the rough-machined part is controlled within ±0.1-0.3 mm. The heat treatment is vacuum heat treatment with a treatment temperature of 850-950℃, a holding time of 2-4 h, a cooling rate of ≤50℃ / h, and an internal stress relief rate of ≥90%.

4. The precision machining process for metal parts according to claim 1, characterized in that: In step S3, the milling speed is 100-150 m / min, the coaxiality error of the boring is ≤0.01 mm, the surface roughness Ra of the semi-finished part is ≤1.6 μm, and a fine grinding allowance of 0.05-0.1 mm is reserved; the ultrasonic cleaning uses deionized water as the medium, the cleaning temperature is 40-60℃, and the cleaning time is 10-20 min. The drying process is hot air drying, with a drying temperature of 80-120℃ and a drying time of 30-60 minutes.

5. The precision machining process for metal parts according to claim 1, characterized in that: In S4, the superhard abrasive wheel is a cubic boron nitride wheel or a diamond wheel, the grinding speed is 30-50 m / s, the grinding depth is 0.001-0.003 mm / cycle, and the cooling and lubrication measures are oil-based cutting fluid; the dimensional tolerance of the ground workpiece is ≤ ±0.005 mm, and the surface roughness Ra is ≤ 0.2 μm; The number of regrinding operations is ≤2 times. Specialized testing equipment includes a coordinate measuring machine, a laser interferometer, and a surface roughness tester.

6. The precision machining process for metal parts according to claim 1, characterized in that: In S6, the rust prevention treatment is passivation or coating with rust-preventive oil; The passivation treatment time is 15-30 min, and the anti-rust oil coating thickness is 5-10 μm.

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