A machining process for precision screws

Abstract

This invention discloses a machining process for precision screws, belonging to the field of mechanical manufacturing technology. It includes the following steps: S1, rough machining and forming: treating the surface of the bar stock and machining functional slot structures, followed by pre-deburring; S2, structural strengthening: heat-treating the workpiece for strengthening; S3, precision finishing: correcting the form and position tolerances of the heat-treated workpiece and precision grinding each surface; S4, quality assurance delivery: completing inspection, cleaning, and packaging. This process flow is clear, employing a logical arrangement of "forming first, then strengthening, and then fine-tuning," resulting in a workpiece with not only a high-hardness surface but also improved coaxiality of its stepped axis and thread trajectory accuracy. This significantly enhances the screw's operational stability at high speeds. Furthermore, through staged quality control and precision correction, it improves the first-pass yield of the workpiece and reduces the risk of scrap due to heat treatment deformation, possessing extremely high industrial application value.

Description

Technical Field

[0001] This invention belongs to the field of mechanical processing and manufacturing technology, and specifically relates to a processing technology for a precision screw. Background Technology

[0002] As a core component of mechanical transmission and fluid transport, screws are widely used in fields such as oil drilling, plastic extrusion, and food processing. With the development of industrial technology, screws are no longer just simple threaded components, but are often designed with composite stepped structures, accompanied by complex internal grooves (such as deflectors) and multiple sets of radial / axial intersecting functional holes.

[0003] For screws with the above-mentioned structure, their machining accuracy directly affects the performance and service life of the equipment. However, the current screw machining process is difficult to balance the manufacturing accuracy of complex structures (inner grooves, multiple sets of functional holes), the efficiency of internal burr removal, and the control of form and position tolerances after heat treatment. Summary of the Invention

[0004] This invention addresses the aforementioned problems in the existing technology by proposing a machining process for precision screws that ensures machining accuracy.

[0005] This invention can be achieved through the following technical solutions: A precision screw machining process is disclosed, wherein the machining object is a bar stock with a stepped structure prefabricated with a small-diameter section, an mounting section, and a large-diameter section, and a transition section is provided between the small-diameter section and the mounting section. The process includes the following steps: S1. Rough machining: The surface of the bar stock is treated and functional hole and groove structures are machined. Finally, pre-deburring is performed. S2. Strengthening the microstructure: Strengthening the workpiece through heat treatment; S3. Precision finishing: Correcting the form and position tolerances of the heat-treated workpiece and precision grinding each surface; S4. Quality Assurance Delivery: Complete testing, cleaning, and packaging.

[0006] As a further improvement of the present invention, step S1 is specifically subdivided into the following sequential steps: S11, Machining and Peeling: Peel off the surface material of the bar stock and perform initial dimensional correction; S12, Functional groove machining: Machining groove structures on the end face, inner wall and outer surface of the bar stock; S13, Functional hole drilling: A first functional hole is machined at the end of the small diameter section near the transition section, and a second functional hole is machined in the transition section and the mounting section; S14. Fluid deburring: Removes internal burrs and sharp edges generated during hole and groove processing.

[0007] As a further improvement of the present invention, in step S11, the oxide layer and pre-stress on the surface of the prefabricated stepped shaft bar are eliminated by three processes: rough turning of the end face, rough turning of the outer circle, and overall fine turning.

[0008] As a further improvement of the present invention, in step S12, the functional groove includes a structural groove drawn on one end face of the large diameter section, a deflector groove machined on the inner wall of the large diameter section, and a thread track groove milled by cyclone milling on the surface of the small diameter section. Step S13 specifically involves machining three sets of the second functional holes that are evenly distributed between the transition section and the mounting section.

[0009] As a further improvement of the present invention, in step S14, an abrasive flow process is adopted to make the semi-solid abrasive medium repeatedly flow through the cross cavity of the second functional hole under pressure.

[0010] As a further improvement of the present invention, step S3 is specifically subdivided into the following sequential steps: S31. Inner hole coaxiality grinding: Simultaneous correction of the inner holes and chamfers at both ends of the workpiece; S32, Spiral Groove Grinding: Fine grinding of the thread trajectory after heat treatment; S33, Fine grinding of outer circle: Precision grinding of the entire outer circle of the workpiece; S34. Cavity grinding and polishing: Grinding and polishing the inner hole of the large-diameter section.

[0011] As a further improvement of the present invention, in step S31, the inner holes of the small diameter section and the large diameter section are ground to make the inner chamfers at both ends of the workpiece coaxial.

[0012] As a further improvement of the present invention, before step S32, a special drilling process is performed on the first functional hole.

[0013] As a further improvement of the present invention, the process also includes an identity recording step set at different nodes: After the thread track groove is machined in step S12, the first marking is performed to record the furnace number of the raw material; A second marking is performed between steps S31 and S32 for the identification of the finished product's digital identity.

[0014] As a further improvement of the present invention, step S4 is specifically subdivided into the following sequential steps: S41. Non-destructive testing: Utilizing magnetic particle or fluorescent technology to inspect surface cracks and grinding burns; S42, Pulse Cleaning: High-pressure pulsed fluid penetrates deep into the hole to remove residual abrasive particles; S43, rust-proof sealing.

[0015] Compared with the prior art, the present invention has the following beneficial effects: 1. High precision retention: Due to the adoption of the "first forming, then strengthening, and then fine calibration" logic arrangement, the workpiece not only has a high hardness surface, but also the coaxiality of its stepped axis and the accuracy of the thread trajectory are improved, which significantly improves the smoothness of the screw's operation at high speed.

[0016] 2. Improved surface quality and lifespan: Through the dual protection of pre-deburring and fine grinding, the roughness of the surface of each section of the workpiece and the inside of the functional holes is greatly reduced, effectively reducing stress concentration or electrostatic corrosion in high-pressure / fluid transportation environments, and significantly improving the overall service life of the screw compared with traditional processes.

[0017] 3. High process flexibility and reliability: The process flow is clear. Through staged quality control (S4) and precision correction (S3), the first-pass yield of stepped workpieces is improved, and the risk of scrap due to heat treatment deformation is reduced. It has extremely high industrial application value.

[0018] 4. Full Lifecycle Digital Traceability and Precision Management: By implementing a dual nested labeling system of S12 (raw material end) and S31 (finished product end), key data such as the original furnace number, heat treatment hardness, and actual precision of finishing of the material are linked in real time to a unique digital identity. This closed-loop traceability mechanism not only enables rapid response to quality anomaly investigations but also greatly enhances the full-process health management capabilities of core components of high-end equipment throughout their service life.

[0019] 5. Ultimate Cleanliness Control for Complex Cavities and Deep Holes: A phased cleaning combination of S14 (pre-fluid deburring) and S42 (post-pulse cleaning) overcomes the industry-wide challenge of abrasive and micro-burr accumulation in deep, long holes and manifolds of precision screws. This deep cleaning treatment of "invisible areas" effectively eliminates the risk of sudden systemic wear caused by micro-particle shedding in high-precision hydraulic or transmission systems, ensuring the high reliability of the precision fluid control system. Attached Figure Description

[0020] Figure 1 This is a schematic diagram of the screw workpiece of the present invention; Figure 2 This is a cross-sectional view of the screw workpiece of the present invention.

[0021] In the diagram, 100 is the workpiece; 101 is the small-diameter section; 102 is the transition section; 103 is the mounting section; 104 is the large-diameter section; 110 is the structural groove; 120 is the deflection groove; 130 is the thread track groove; 140 is the first functional hole; and 150 is the second functional hole. Detailed Implementation

[0022] The following are specific embodiments of the present invention, which are described in conjunction with the accompanying drawings to further illustrate the technical methods of the present invention. However, the present invention is not limited to these embodiments.

[0023] like Figures 1-2 As shown, the present invention provides a machining process for a precision screw, the machining object being a bar stock with a stepped structure prefabricated with a small-diameter section 101, an mounting section 103, and a large-diameter section 104, wherein a transition section 102 is provided between the small-diameter section 101 and the mounting section 103, and the process includes the following steps: S1. Rough machining: The surface of the bar stock is treated and functional hole and groove structures are machined. Finally, pre-deburring is performed. S2. Strengthening the microstructure: Strengthening the workpiece 100 by heat treatment; S3. Precision finishing: Correcting the form and position tolerances and precision grinding each surface of the heat-treated workpiece 100. S4. Quality Assurance Delivery: Complete testing, cleaning, and packaging.

[0024] This process provides a complete solution to the technical bottlenecks in existing screw machining, such as poor positioning accuracy of stepped structures, difficulty in correcting heat treatment deformation, and incomplete removal of internal burrs. To address the challenge of machining complex features: Step S1 involves surface stripping, forming functional grooves and multiple sets of functional holes before material heat treatment. By utilizing the material's low cutting resistance, tool wear and machining stress that are prone to occur when machining deep holes or complex grooves on hardened materials are effectively avoided, ensuring the initial positional accuracy of the hole and groove structure.

[0025] To address the issue of uncontrolled deformation during heat treatment: Step S3 adds a "precision finishing" stage after microstructural strengthening, specifically addressing the dimensional and positional tolerance correction caused by uneven thickness during heat treatment due to thermal stress and deformation. By utilizing grinding and lapping strategies instead of single cutting operations, the persistent problem of coaxiality deviations in stepped structural components is fundamentally solved.

[0026] Addressing the challenge of cleanliness in multi-step components: By systematically pre-processing the encapsulation in step S4, detection and cleaning are deeply coupled, effectively solving the problem of tiny abrasive or metal residues remaining in the corners and inner holes of complex steps after rough machining and fine grinding, thus eliminating the risk of early wear during operation.

[0027] The improved process has at least the following advantages compared to existing technologies: 1. High precision retention: Due to the adoption of the "first forming, then strengthening, and then fine calibration" logic arrangement, the workpiece 100 not only has a high hardness surface, but also the coaxiality of its stepped axis and the accuracy of the thread trajectory are improved, which significantly improves the smoothness of the screw's operation at high speed.

[0028] 2. Improved surface quality and lifespan: Through the dual protection of pre-deburring and fine grinding, the roughness of the surface of each section of the workpiece and the inside of the functional holes is greatly reduced, effectively reducing stress concentration or electrostatic corrosion in high-pressure / fluid transportation environments, and significantly improving the overall service life of the screw compared with traditional processes.

[0029] 3. High process flexibility and reliability: The process flow is clear. Through staged quality control (S4) and precision correction (S3), the first-pass yield of the stepped workpiece 100 is improved, and the risk of scrap due to heat treatment deformation is reduced. It has extremely high industrial application value.

[0030] Preferably, step S1 is further subdivided into the following sequential steps: S11, Machining and Peeling: Peel off the surface material of the bar stock and perform initial dimensional correction; S12, Functional groove machining: Machining groove structures on the end face, inner wall and outer surface of the bar stock; S13, Functional hole drilling: The first functional hole 140 is machined at the end of the small diameter section 101 near the transition section 102, and the second functional hole 150 is machined in the transition section 102 and the mounting section 103. S14. Fluid deburring: Removes internal burrs and sharp edges generated during hole and groove processing.

[0031] Through the synergistic effect of S11 to S14, this refining process first uses machining to effectively eliminate the surface stress and impurities of the original bar stock, laying a stable baseline for subsequent high-precision machining. Subsequently, through the orderly forming of functional slots in different regions and functional holes in multiple nodes, the balanced construction of internal and external features between complex stepped structures was precisely achieved, which greatly reduced tool wear and avoided the original deformation caused by residual stress in the material before heat treatment. Finally, fluid deburring technology was used to achieve full coverage cleaning of the stepped transition section 102 and the sharp edges inside the cross holes, which are difficult to reach by mechanical means.

[0032] Preferably, in step S11, the oxide layer and pre-stress on the surface of the prefabricated stepped shaft bar are eliminated through three processes: rough turning of the end face, rough turning of the outer circle, and overall finish turning.

[0033] Through three sequential machining processes from coarse to fine, this process not only effectively removes the deteriorated oxide layer from the surface of the original bar stock, providing a regular and uniform geometric positioning benchmark, but more importantly, it fully releases and balances the uneven residual stress generated by the raw material during the preforming process through step-by-step cutting. This prevents uncontrollable deformation of the workpiece 100 in subsequent complex machining stages and heat treatment processes from the source, significantly improving the dimensional stability and benchmark consistency of the entire machining chain.

[0034] Preferably, in step S12, the functional groove includes a structural groove 110 drawn on one end face of the large diameter section 104, a flexible groove 120 machined on the inner wall of the large diameter section 104, and a thread trajectory groove 130 milled by cyclone milling on the surface of the small diameter section 101. This achieves a high degree of integration of the screw's multi-functional characteristics: by using the combined processing of the end face structural groove 110, the inner wall flexible groove 120 and the cyclone milled thread trajectory groove 130, not only is the efficiency of power transmission and the forming accuracy of the thread profile ensured, but the dynamic mechanical properties of the workpiece 100 are also optimized by introducing the flexibility of the inner wall. Step S13 specifically involves machining three sets of uniformly distributed second functional holes 150 in the transition section 102 and the mounting section 103, which greatly balances the stress distribution inside the complex stepped component and avoids operational instability or heat treatment distortion caused by asymmetrical machining positions, thereby significantly improving the structural stability and dynamic service life of the precision screw under complex working conditions.

[0035] Preferably, in step S14, an abrasive flow process is used, in which semi-solid abrasive media repeatedly flows under pressure through the intersecting inner cavity of the second functional hole 150. This process utilizes the pressure permeability and fluid characteristics of abrasive flow technology, enabling the semi-solid abrasive to precisely reach the intersecting inner cavity that conventional mechanical tools cannot access. Through the repeated flushing action of the abrasive media, hidden burrs at the intersection of the channels are thoroughly removed, and sharp edges are trimmed into tiny rounded corners.

[0036] This not only significantly improves the surface quality and fluid motion characteristics of the inner wall of the functional hole, but also effectively eliminates stress concentration at the sharp corners of the cross holes, fundamentally preventing system failures caused by burr shedding or stress cracks during subsequent service of the screw, and significantly enhancing the structural fatigue strength and long-term operational controllability of the parts.

[0037] Preferably, step S3 is further subdivided into the following sequential steps: S31. Inner hole coaxiality grinding: Simultaneously correct the inner holes and chamfers at both ends of workpiece 100; S32, Spiral Groove Grinding: Fine grinding of the thread trajectory after heat treatment; S33, Fine grinding of outer diameter: Precision grinding of the entire outer diameter of the workpiece; S34, Cavity grinding and polishing: Grinding and polishing the inner hole of the large-diameter section 104.

[0038] Through a stepped finishing system from S31 to S34, this process achieves 100° omnidirectional precision reconstruction of the workpiece's shape and position after heat treatment. Firstly, by simultaneously correcting the inner hole and chamfer (S31), the geometric distortion caused by heat treatment deformation was effectively eliminated, and a high-precision coaxial positioning datum was established. The subsequent spiral groove fine grinding (S32) and outer circle fine grinding (S33) further corrected the core transmission trajectory and mating surface at the micron level, ensuring the stability and transmission accuracy of the screw under high load operation; Finally, the cavity polishing (S34) significantly improved the surface finish of the internal functional surfaces, which not only eliminated the hidden danger of micro-stress concentration, but also enabled the workpiece 100 to achieve a high-precision state with both internal and external finishes, greatly enhancing the fatigue resistance of the finished product and the assembly fit between various components.

[0039] Preferably, in step S31, the inner holes of the small diameter section 101 and the large diameter section 104 are ground to make the inner chamfers at both ends of the workpiece 100 coaxial. This process, through targeted grinding of the inner holes of the small diameter section 101 and the large diameter section 104, forcibly establishes the coaxial constraint of the inner chamfers at both ends of the workpiece 100, fundamentally correcting the axial deviation that may be caused by heat treatment.

[0040] This precision correction mechanism not only establishes a highly unified benchmark for the entire machining process, but also eliminates the geometric deviation caused by the deformation of the inner hole of the workpiece 100. This ensures that the radial runout of the screw is kept at an extremely low level during subsequent precision machining and actual service, providing core quality support for improving the dynamic balance performance and axial transmission accuracy of the parts.

[0041] Preferably, before step S32, a special drilling process is performed on the first functional hole 140. By introducing a special drilling process for the first functional hole 140 before the spiral groove fine grinding in S32, this process can accurately repair the slight geometric distortion and dimensional drift of the functional hole after heat treatment, and ensure that the roundness, cylindricity and surface roughness of the hole wall reach the stringent design threshold.

[0042] This step not only reserves the optimal fit space for the precise installation of key components in the hole position, but more importantly, by completing the correction of the internal hole diameter in advance, it eliminates the interference that may be caused by positioning deviation or residual stress fluctuation in subsequent processing on the accuracy of the screw drive trajectory. It realizes the high precision coordination between the internal functional position of the part and the external power trajectory, and systematically improves the overall assembly consistency and service reliability of the component.

[0043] Preferably, the process also includes identity recording procedures at different nodes: After the machining of the thread track groove 130 is completed in step S12, the first marking is performed to record the raw material furnace number. This provides an accurate source investigation basis for possible batch quality fluctuations in the future, ensuring the bottom-level controllability of quality management. This marking is used for traceability at the raw material end. A second marking is performed between steps S31 and S32 for digital identification of finished products, so as to form digital management of finished products.

[0044] Preferably, step S4 is further subdivided into the following sequential steps: S41. Non-destructive testing: Utilizing magnetic particle or fluorescent technology to inspect surface cracks and grinding burns; S42, Pulse Cleaning: High-pressure pulsed fluid penetrates deep into the hole to remove residual abrasive particles; S43, rust-proof sealing.

[0045] Through the detailed steps of the S4 stage, this process completes the final quality loop from process manufacturing to finished product delivery: Structural integrity verification (S41): Using magnetic particle or fluorescent non-destructive testing, it is possible to accurately identify micro-cracks invisible to the naked eye and surface burns caused by grinding stress, ensuring that each finished product has excellent fatigue strength and structural reliability, and eliminating potential safety hazards.

[0046] Deep cleaning (S42): For precision channels and complex surfaces, the powerful cavitation effect of high-pressure pulsed fluid is used to thoroughly remove and carry away micron-sized abrasive particles remaining in dead corners, preventing abnormal wear caused by residues during subsequent assembly or use.

[0047] Full lifecycle protection and delivery (S43): Through scientific rust prevention treatment and standardized packaging, the oxidation and corrosion of precision surfaces by the external environment are isolated, ensuring that parts maintain their initial high precision performance throughout the entire process of warehousing and transportation.

[0048] This system not only provides the final verification of the processing results, but also serves as a systematic refinement of the product's long-term service stability, ensuring that the precision screw meets high-precision delivery standards during final assembly.

[0049] To better illustrate this, the detailed process flow steps are attached below: 1. First stage: Matrix preforming and feature construction (S1) (1) S11, machining and stripping Process details: The surface material of the bar stock is stripped to remove the decarburized layer and structural defects from the surface of the raw material.

[0050] Objective: To perform initial dimensional calibration and reserve appropriate machining allowances for the outer cylindrical datum in subsequent precision machining.

[0051] (2) S12, Functional slot processing and preliminary traceability Process details: Functional slots are machined on the end face, inner wall and outer surface of workpiece 100.

[0052] Marking node: After processing is completed, the first marking is carried out to record the material furnace number and batch information and establish the original file.

[0053] (3) S13, Functional hole drilling First functional hole 140: Precision drilling is performed at the end of the small diameter section 101 near the transition section 102.

[0054] Second functional hole 150: The second function drilling is completed in the transition section 102 and the mounting section 103 to ensure that the spatial position meets the design requirements.

[0055] (4) S14, fluid deburring Process details: Using fluid grinding or high-pressure fluid flushing technology, thoroughly remove the internal burrs and sharp edges generated in the inner holes and intersecting grooves to prevent stress concentration and microcracks during heat treatment.

[0056] 2. Second Phase: Organizational Strengthening (S2) S2, Tissue Enhancement Treatment Process content: Perform overall or partial heat treatment on workpiece 100 (such as quenching, tempering, carburizing, etc.).

[0057] Objective: To improve the hardness, strength, and wear resistance of the workpiece by 100, and to stabilize the microstructure.

[0058] 3. Third stage: High-precision correction and surface grinding (S3) (1) S31, grinding and digital establishment of inner hole coaxiality Core action: Simultaneously fine-grind and correct the inner holes and chamfers at both ends of workpiece 100 to forcibly eliminate geometric distortions caused by heat treatment.

[0059] Marking node: After the correction is completed, a second marking is performed to give the workpiece a unique digital finished product identity and record the key precision compensation amount.

[0060] (2) S32, spiral groove grinding Process details: Based on the coaxial reference modified by S31, the heat-treated thread / helix trajectory is ground with high precision to ensure the geometric parameters of the transmission pair.

[0061] (3) S33, fine grinding of the outer circle Process details: Perform final finishing on the outer diameter of the workpiece to ensure the dimensional tolerances of the outer diameter and its coaxiality with the inner axis.

[0062] (4) S34, cavity polishing Process details: Deep grinding and multi-pass polishing are performed on the inner hole of the large-diameter section 104 to improve surface smoothness and reduce fluid resistance or friction coefficient.

[0063] 4. Phase Four: Quality Verification and Delivery Protection (S4) (1) S41, Non-destructive testing Process details: Magnetic particle testing or fluorescent penetrant testing is used to inspect the surface and stress concentration areas for defects such as cracks and grinding burns.

[0064] (2) S42, pulse cleaning Process details: High-pressure pulsed fluid is used to penetrate deep into each functional hole and groove to completely remove and rinse away residual particles (such as polishing paste and metal powder).

[0065] (3) S43, anti-rust sealing Process details: Surface anti-rust treatment and standardized physical packaging are carried out to ensure that the finished product maintains stable performance before storage, transportation and final assembly.

[0066] The technical means disclosed in this invention are not limited to those described above, but also include technical solutions composed of any combination of the above technical features. The above are specific embodiments of this invention. It should be noted that those skilled in the art can make various improvements and modifications without departing from the principle of this invention, and these improvements and modifications are also considered within the scope of protection of this invention.

[0067] It should be noted that all directional indications (such as up, down, left, right, front, back, etc.) in the embodiments of the present invention are only used to explain the relative positional relationship and movement of each component in a certain specific posture (as shown in the figure). If the specific posture changes, the directional indication will also change accordingly.

[0068] Furthermore, in this invention, the use of terms such as "first," "second," and "a" is for descriptive purposes only and should not be construed as indicating or implying their relative importance or implicitly specifying the number of technical features indicated. Therefore, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature. In the description of this invention, "a plurality of" means at least two, such as two, three, etc., unless otherwise explicitly specified. The terms "connection," "fixed," etc., should be interpreted broadly. For example, "fixed" can mean a fixed connection, a detachable connection, or an integral part; it can mean a mechanical connection or an electrical connection; it can mean a direct connection or an indirect connection through an intermediate medium; it can mean the internal communication of two elements or the interaction between two elements, unless otherwise explicitly specified. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0069] The technical solutions of the various embodiments of the present invention can be combined with each other, but only if they are based on the ability of those skilled in the art to implement them. When the combination of technical solutions is contradictory or cannot be implemented, it should be considered that such combination of technical solutions does not exist and is not within the scope of protection claimed by the present invention.

[0070] The specific embodiments described herein are merely illustrative of the spirit of the invention. Those skilled in the art to which this invention pertains may make various modifications or additions to the described specific embodiments or use similar methods to substitute them, without departing from the spirit of the invention or exceeding the scope defined by the appended claims.

Claims

1. A machining process for a precision screw, wherein the machining object is a bar stock prefabricated with a small-diameter section, an mounting section, and a stepped structure of a large-diameter section, wherein a transition section is provided between the small-diameter section and the mounting section, characterized in that, The process includes the following steps: S1. Rough machining: The surface of the bar stock is treated and functional hole and groove structures are machined. Finally, pre-deburring is performed. S2. Strengthening the microstructure: Strengthening the workpiece through heat treatment; S3. Precision finishing: Correcting the form and position tolerances of the heat-treated workpiece and precision grinding each surface; S4. Quality Assurance Delivery: Complete testing, cleaning, and packaging.

2. The machining process for a precision screw according to claim 1, characterized in that: Step S1 is further subdivided into the following sequential steps: S11, Machining and Peeling: Peel off the surface material of the bar stock and perform initial dimensional correction; S12, The processing of the functional groove: Groove structures are processed on the end face, inner wall and outer surface of the bar stock; S13, Functional hole drilling: A first functional hole is machined at the end of the small diameter section near the transition section, and a second functional hole is machined in the transition section and the mounting section; S14. Fluid deburring: Removes internal burrs and sharp edges generated during hole and groove processing.

3. The machining process for a precision screw according to claim 2, characterized in that: In step S11, the oxide layer and pre-stress on the surface of the prefabricated stepped shaft bar are eliminated through three processes: rough turning of the end face, rough turning of the outer circle, and overall finish turning.

4. The machining process for a precision screw according to claim 2, characterized in that: In step S12, the functional groove includes a structural groove drawn on one end face of the large diameter section, a deflector groove machined on the inner wall of the large diameter section, and a thread track groove milled by cyclone milling on the surface of the small diameter section. Step S13 specifically involves machining three sets of the second functional holes that are evenly distributed between the transition section and the mounting section.

5. The machining process for a precision screw according to claim 2, characterized in that: In step S14, an abrasive flow process is used to make the semi-solid abrasive medium flow repeatedly through the cross cavity of the second functional hole under pressure.

6. The machining process for a precision screw according to claim 1, characterized in that: Step S3 is further subdivided into the following sequential steps: S31. Inner hole coaxiality grinding: Simultaneous correction of the inner holes and chamfers at both ends of the workpiece; S32, Thread track groove grinding: Fine grinding of the heat-treated thread track; S33, Fine grinding of outer circle: Precision grinding of the entire outer circle of the workpiece; S34. Cavity grinding and polishing: Grinding and polishing the inner hole of the large-diameter section.

7. The machining process for a precision screw according to claim 6, characterized in that: In step S31, the inner holes of the small diameter section and the large diameter section are ground to make the inner chamfers at both ends of the workpiece coaxial.

8. The machining process for a precision screw according to claim 6, characterized in that: Before step S32, a special drilling process is performed on the first functional hole.

9. The machining process for a precision screw according to claim 1, characterized in that: The process also includes identity recording procedures at different nodes: After the machining of the thread track groove is completed in step S12, the first marking is performed to record the raw material furnace number; A second marking is performed between steps S31 and S32 for the identification of the finished product's digital identity.

10. The machining process for a precision screw according to claim 1, characterized in that: Step S4 is further subdivided into the following sequential steps: S41. Non-destructive testing: Utilizing magnetic particle or fluorescent technology to inspect surface cracks and grinding burns; S42, Pulse Cleaning: High-pressure pulsed fluid penetrates deep into the hole to remove residual abrasive particles; S43, rust-proof sealing.

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