Plunger ring machining process

Abstract

The plunger ring machining technology is implemented according to the following steps that S1, a blank is prepared and used for manufacturing an annular blank; s2, size rough machining is conducted, specifically, size rough machining is conducted on the annular blank; s3, performance strengthening is carried out to improve the fatigue strength and prolong the service life of the plunger ring; s4, size finish machining is conducted, specifically, size finish machining is conducted on the plunger ring subjected to performance strengthening; s5, opening machining, wherein opening machining is implemented through the following steps that S51, a crack is machined in the inner diameter position of the plunger ring; s52, applying outward opening torque from the inner diameter of the plunger ring so as to generate a breaking joint between the bottom of the crack and the outer diameter of the plunger ring, wherein the breaking joint enables the crack to be connected with the plunger ring; s6, surface hardening treatment is carried out for improving the wear resistance and corrosion resistance of the plunger ring; and S7, finished product post-treatment is carried out to guarantee the use adaptability, quality reliability and storage and transportation safety of the finished product. The method has the beneficial effects that the opening strategy of presplitting and then supporting is adopted for machining the opening of the plunger ring.

Description

Technical Field

[0001] This invention relates to a plunger ring processing technology. Background Technology

[0002] In existing technology, the openings (usually grooves or slits) on plunger rings play a crucial role in both installation and operation. During installation, the openings provide the plunger ring with the necessary elasticity, allowing it to expand appropriately and smoothly fit into the plunger or shaft, avoiding installation difficulties or damage caused by rigid structures. During operation, the openings allow the plunger ring to adaptively adjust to thermal expansion, mechanical stress, or pressure fluctuations, maintaining tight contact with the cylinder wall, ensuring sealing performance, preventing fluid leakage, and distributing forces on the ring to extend its service life. This design balances the ring's fixed and dynamic requirements, forming the basis for efficient plunger ring operation.

[0003] However, existing manufacturing processes for plunger ring openings have significant drawbacks. Common methods include mechanical cutting, stamping, or laser cutting. These processes often result in uneven opening edges, burrs, or microcracks, and may even prevent the formation of a complete and regular opening due to processing errors. Uneven openings increase frictional resistance during installation, affecting the ring's elastic expansion and potentially leading to jamming or deformation. During operation, rough edges exacerbate wear, cause stress concentration, reduce sealing effectiveness, and ultimately affect the overall performance and reliability of the plunger ring. Summary of the Invention

[0004] To address the shortcomings of existing technologies, this invention provides a plunger ring processing technology that can improve the opening quality and sealing reliability of plunger rings.

[0005] To achieve the above objectives, the technical solution of the present invention is as follows: a plunger ring processing technology, implemented according to the following steps: S1, blank preparation, used to make ring-shaped blanks; S2, rough machining of dimensions, rough machining of the ring blank; S3, performance enhancement, is used to improve the fatigue strength and service life of plunger rings; S4, Dimensional finishing, performs dimensional finishing on the enhanced plunger rings; S5, Opening process, which is performed through the following steps: S51, A crack is machined at the inner diameter of the plunger ring, the crack extends from the inner diameter of the plunger ring toward the outer diameter, and the crack does not reach the outer diameter of the plunger ring. S52, apply an outwardly expanding torque from the inner diameter of the plunger ring to create a fracture gap connecting the bottom of the crack to the outer diameter of the plunger ring. S6, surface hardening treatment, used to improve the wear resistance and corrosion resistance of plunger rings; S7, Post-processing of finished products, is used to ensure the usability, quality reliability and storage and transportation safety of finished products.

[0006] The beneficial effects of this invention are as follows: The core of this process lies in the adoption of a "pre-crack followed by support" opening strategy. This involves first machining a pre-fabricated crack at the inner diameter that does not penetrate the outer diameter, and then naturally expanding the crack tip from the inner diameter outwards until it connects with the outer diameter at a predetermined position to form a fracture. This method fundamentally avoids the inherent defects of traditional methods that directly complete the opening, such as mechanical cutting, stamping, or laser cutting. Because the fracture is a controlled fracture guided by the pre-fabricated crack, rather than being directly cut through by a tool, the fracture edge is smooth, burr-free, or free of microcracks, resulting in a more reasonable stress distribution. This significantly improves the smoothness of the plunger ring's expansion during installation, reducing the risk of jamming. In operation, the smooth fracture edge effectively reduces wear and avoids stress concentration, thereby ensuring the ring's elastic recovery capability and long-term sealing stability, ultimately improving the overall reliability and lifespan of the plunger pump. As a preferred embodiment, the pre-fabricated crack can be a groove or a series of micropores machined on the inner diameter surface of the plunger ring, with the depth direction facing the outer diameter but not reaching the outer surface. Subsequently, an expansion tool (such as a tapered mandrel) with a diameter slightly larger than the inner diameter of the plunger ring is passed through the inner hole of the ring. The tool applies a uniform radial expansion force to the inner hole wall, causing the material at the bottom of the pre-made crack to undergo ductile fracture under tensile stress. The crack steadily extends to the outer diameter surface along a preset path, eventually forming a fracture with uniform width and neat edges.

[0007] Furthermore, the crack in step S51 has a V-shaped groove in cross-section, and the tip of the V-shaped groove is positioned towards the outer diameter of the plunger ring.

[0008] This technical solution specifically defines the crack opening as a V-shaped groove structure, offering multiple beneficial effects. First, the well-defined geometry of the V-groove facilitates its formation using various precision machining methods (such as electrical pulse machining and grinding), resulting in high machining accuracy and consistency. Second, the tip of the V-groove acts as a natural stress concentrator, ensuring that stress is highly concentrated at the tip when a spreading force is applied subsequently. This guarantees that the crack starts at a predetermined location (the tip) and propagates precisely and stably along the direction pointing outwards from the tip, thus achieving a fracture with controllable location and morphology. Furthermore, the sidewalls of the V-groove provide excellent guidance for crack propagation, contributing to the formation of a straight and neat fracture side. The design of the V-groove also considers structural strength; its opening angle ensures sufficient groove width for easy machining and observation, while the sharp tip minimizes the weakening of the overall structural integrity of the ring, maintaining the ring's load-bearing capacity while ensuring the quality of the opening. As a preferred embodiment, the V-groove is formed by the convergence of two symmetrical, inclined sidewalls at a line or a small arc surface to create the tip. When the plunger ring is subjected to an expansion force extending from the inner radial direction outward, the tip region of the V-groove reaches the material's fracture strength first, initiating a crack. Due to the constraint and guiding effect of the groove sidewalls, the crack mainly propagates along the groove depth direction (i.e., towards the outer diameter of the ring) and does not easily deflect to either side, thus efficiently and accurately generating the desired fracture. Under working pressure, the V-shaped profile of this structure has a certain self-locking effect, which helps maintain the stability of the open state.

[0009] Furthermore, the included angle formed by the V-shaped groove opening is 30°, and the groove depth from the V-shaped groove opening to its tip is 38-40% of the difference between the outer diameter and the inner diameter of the plunger ring.

[0010] Limiting the V-groove angle to 30° and the groove depth to a specific ratio of the wall thickness (the difference between the outer and inner diameters) yields beneficial optimization and synergistic effects. The 30° angle is a balanced choice: too small an angle might result in an overly sharp groove tip, easily inducing microcracks during machining or heat treatment; too large an angle weakens the stress concentration effect, potentially affecting the accuracy of crack initiation. The 30° angle provides sufficient stress concentration coefficient while ensuring good machinability. Setting the groove depth to 38-40% of the wall thickness aims to precisely control the depth of the pre-crack. This depth range ensures sufficient crack length to effectively guide the crack, while leaving approximately 60-62% of the wall thickness as a "ligament." During the unfolding process, this ligament material undergoes plastic deformation until fracture. Its optimized thickness ensures a controllable fracture process, a good fracture morphology (no burrs caused by excessive plastic deformation), and a final fracture width within an ideal range, thereby optimizing the closing elasticity and sealing performance after plunger ring installation. As a preferred method, a shaped electrode or shaped grinding wheel is used during processing to precisely replicate a V-shaped profile with a 30° included angle and a calculated depth. This specific combination of angle and depth allows the crack, after initiating from the V-tip, to form a stable plane strain state within the remaining ligament during the subsequent fracture process. This enables the crack to quickly penetrate the ligament and reach the outer surface in a relatively straight manner, forming a fracture with neat edges and consistent width, thus avoiding drift in the crack propagation path or the appearance of tearing burrs on the fracture surface.

[0011] Furthermore, the crack in step S51 is formed by electrical pulse forming.

[0012] Employing electro-pulse forming (EPF) technology to manufacture the aforementioned cracks (V-grooves) significantly improves the precision and surface quality of the opening process, resulting in a series of beneficial effects. EPF is a non-contact machining process that uses the heat energy generated by pulsed discharge to erode the material. Its machining precision can reach the micrometer level, enabling extremely accurate reproduction of the V-groove design dimensions and angles, ensuring the consistency of pre-fabricated cracks on each plunger ring. More importantly, the groove wall surface after EPF forms a remelted and resolidified "white layer," which is dense, has high hardness, and a surface roughness superior to many machining methods. The smooth groove wall reduces microscopic notches and stress concentration points, which not only facilitates a smoother fracture surface during cracking but also improves the fatigue strength of the plunger ring under alternating loads. Furthermore, the absence of mechanical cutting forces avoids deformation that may occur in thin-walled annular parts during machining, making it particularly suitable for precision machining of heat-treated hard materials. As a preferred method, a forming electrode made of brass or copper, complementary to the desired V-groove shape, is used for machining on a precision EDM machine. During processing, a set gap is maintained between the electrode and the inner diameter surface of the plunger ring. Pulsed discharge is generated in the insulating working fluid. By precisely controlling the discharge parameters (such as current, pulse width, and gap voltage), the material is gradually etched away until a V-shaped groove with precise dimensions and a smooth surface is formed. This process does not generate macroscopic mechanical stress and has minimal impact on the metallographic structure of the ring and the strengthened surface properties.

[0013] Furthermore, the width of the fracture is less than one-sixth of the difference between the outer and inner diameters of the plunger ring.

[0014] A maximum limit is set on the final gap width, stipulating that it be less than one-sixth of the ring wall thickness (the difference between the outer and inner diameters). This technical feature is crucial for ensuring the core function of the plunger ring. A narrow and uniform gap width is key to ensuring effective closure and sealing of the plunger ring after it is installed on the piston rod. An excessively wide gap will result in a noticeable gap after the ring is closed, significantly reducing its radial sealing capability and leading to media leakage. Controlling the width to a small proportion of the wall thickness means that the arc length of the gap in the circumferential direction of the ring is very short. When the ring is installed and closed, this narrow gap can be "bridging" through the ring's own elastic deformation and slight misalignment under operating pressure, thus achieving near-continuous sealing contact. In addition, the narrow gap also helps maintain the continuity of the ring structure, allowing it to maintain better overall rigidity and stability during high-pressure reciprocating motion, reducing the risk of uneven stress distribution or abnormal wear caused by an excessively large opening. As a preferred method, by precisely controlling the depth of the prefabricated V-groove (as mentioned above, 38-40% of the wall thickness) and the final expansion amount of the spreading tool (such as a tapered mandrel), the fracture width can be actively controlled within a preset narrow range. Specifically, during the fracture-spreading process, when the tapered mandrel passes through and extends the crack to the outer diameter, an initial opening is created in the ring. By designing the maximum diameter of the mandrel to be slightly larger than the inner diameter of the ring in its installed state, it can be ensured that the resulting fracture width just meets the amount required to be spread during installation, while in the free state or after installation and closure, this width is much less than one-sixth of the wall thickness, thus meeting high sealing requirements.

[0015] Furthermore, in step S52, a truncated cone is used to pass through the inner diameter of the plunger ring to create a fracture between the bottom of the crack and the outer diameter of the plunger ring. The outer diameter of one end face of the truncated cone is smaller than the inner diameter of the plunger ring, and the outer diameter of the other end face is larger than the inner diameter of the plunger ring.

[0016] Using a truncated cone (i.e., a conical mandrel) of a specific size as the fracture induction tool provides a controllable, stable, and efficient fracture induction method. The structural characteristics of the truncated cone allow one end (the smaller end) to be easily inserted into the inner bore of the plunger ring. As the cone is gradually pushed in, the radial expansion force on the inner bore wall increases smoothly and continuously from zero. This gradual force application avoids impact loads, allowing the stress at the pre-existing crack tip to accumulate smoothly, which is beneficial for the stable initiation and propagation of cracks, resulting in a clean fracture surface. One side of the tool has a diameter smaller than the inner diameter of the ring, ensuring smooth insertion and alignment; the other side has a diameter larger than the inner diameter of the ring, providing the necessary interference fit to generate fracture. This method is highly mechanized and standardized, easily automated on the production line, ensures consistency in fracture formation quality between different products, and is simple to operate without impact damage to parts. As a preferred embodiment, the truncated cone tool is made of a high-hardness, wear-resistant material, and its axis is aligned with the axis of the plunger ring. During the advancement process, the conical surface slides into contact with the inner diameter surface of the ring, generating uniform radial pressure. This pressure is transmitted through the ring body to the tip of the pre-fabricated V-groove. When the stress exceeds the material's fracture strength, a crack initiates at the V-tip and propagates radially outward along the direction of the conical surface's advancement until it penetrates the remaining wall thickness to form a fracture. The linear dimensional advancement of the cone directly translates into the radial displacement of the ring, and the amount of displacement is controllable, thus indirectly controlling the final width of the fracture.

[0017] Furthermore, the outer diameter of one end face of the truncated cone is 0.03-0.05 mm smaller than the inner diameter of the plunger ring, and the outer diameter of the other end face is 0.13-0.15 mm larger than the inner diameter of the plunger ring. The taper of the truncated cone is 1:200-1:250.

[0018] The precise dimensional parameters of the truncated cone are defined, including a tiny gap at the inlet end (0.03-0.05mm), an interference fit at the working end (0.13-0.15mm), and an extremely gentle taper (1:200-1:250). These parameters work together to achieve ultra-fine control over the cracking process. The extremely small inlet gap ensures that the tool can smoothly and accurately enter the inner hole, reducing deflection. The gentle taper design means that the diameter increases only slightly for each long advance of the tool, resulting in a very gradual increase in radial expansion force. This gradual increase in force gives the material sufficient response time, allowing the crack to propagate stably in a near-static manner, greatly reducing the possibility of crack bifurcation or irregular fracture, and ensuring a straight and smooth fracture edge. The final interference fit of 0.13-0.15mm is calculated to provide sufficient total expansion to ensure that the crack completely penetrates the wall thickness and forms an initial opening width that meets installation requirements, while avoiding excessive expansion that could cause unnecessary plastic deformation or damage to the ring. As a preferred method, in automated equipment, the plunger ring is precisely positioned and fixed, and a carbide tapered mandrel with the aforementioned specific taper and dimensions is advanced uniformly along the horizontal axis. The small end of the mandrel is first guided into the ring hole with a tiny gap, and then the tapered surface begins to contact and expand the ring body. Due to the extremely gentle taper, the expansion process is smooth. When the mandrel is advanced to a position where the diameter of the large end is approximately 0.13-0.15 mm larger than the inner diameter of the ring, the stress at the pre-formed crack is just sufficient to allow the crack to propagate to the outer surface, completing the fracture formation. The entire process combines force control and displacement control, resulting in excellent repeatability.

[0019] Furthermore, step S3 is implemented through the following steps: S31, heat treatment, the plunger ring is quenched and tempered by a combination of quenching and high-temperature tempering; The quenching parameters are as follows: heat to 830-860℃, hold for 10-15 minutes, and then quickly oil-cool or water-cool to obtain a martensitic structure; The high-temperature tempering parameters are as follows: 500-650℃, not less than three hours, followed by air cooling; S32, shot peening, shot peening intensity 0.3mmA, coverage 200%, using high-speed shot stream to impact the surface of the part.

[0020] The performance enhancement of plunger rings is achieved through a combined process of tempering heat treatment followed by shot peening, comprehensively improving both the matrix mechanical properties and surface fatigue resistance, resulting in a synergistic enhancement effect. Tempering (quenching + high-temperature tempering) first endows the material with excellent comprehensive mechanical properties: quenching yields a high-strength martensitic structure, and subsequent high-temperature tempering decomposes the martensite, significantly improving toughness and plasticity while maintaining high hardness, resulting in a sorbitic structure with a hardness in the HRC 35-45 range. This structure provides the plunger ring with sufficient rigidity to maintain shape accuracy, while also possessing good elasticity to withstand repeated deformation during installation and operation. The shot peening process, based on this, uses high-speed shot impacts to introduce a residual compressive stress field into the surface and subsurface layers. This compressive stress field effectively counteracts the tensile stress generated by alternating loads during operation, greatly delaying the initiation and propagation of fatigue cracks, thereby significantly improving the fatigue strength and service life of the parts. These two processes cannot be reversed. First, heat treatment determines the matrix properties, then shot peening strengthens the surface, laying a solid foundation for subsequent precision machining of the plunger ring and long-term reliable operation under harsh conditions. As a preferred method, the heat treatment is carried out in a controlled atmosphere furnace or vacuum furnace to ensure uniform heating and prevent oxidation and decarburization. Rapid oil cooling is used during quenching to obtain uniform martensite and reduce deformation. High-temperature tempering involves long-term holding to allow for complete microstructure transformation and effective elimination of internal stress. Shot peening uses specialized equipment with high-hardness ceramic microspheres as projectiles. By precisely controlling the projectile flow rate, volume, and spray angle, the specified strength (0.3 mmA) and coverage (200%) are ensured, thereby forming a residual compressive stress layer of uniform depth and distribution on the part surface. Attached Figure Description

[0021] Figure 1 This is a front view of the plunger ring processed according to an embodiment of the present invention; Figure 2 This is a cross-sectional view along the AA direction of the plunger ring processed according to an embodiment of the present invention; Figure 3 This is a partial enlarged view of the plunger ring I processed according to an embodiment of the present invention. (Where B is the crack and C is the fracture). Detailed Implementation

[0022] An embodiment of the present invention provides a plunger ring processing technology implemented according to the following steps: S1, blank preparation, used to make ring-shaped blanks; Cold-rolled steel strip or seamless steel pipe is used to form a ring-shaped blank through punching or cutting to ensure initial dimensional accuracy and material uniformity.

[0023] S2, rough machining of dimensions, rough machining of the ring blank; Step S2 specifically includes: S21, Soft grinding end face: Grinding two end faces on a double-end face grinder. The purpose is to remove initial marks and obtain a flat and uniformly thick blank, providing a precision reference for subsequent machining. S22, Turning: Turning the blank to initially machine the inner diameter, outer diameter, end face, and chamfer, removing most of the excess material and laying the foundation for finishing. A CNC lathe is used to turn the outer diameter, inner diameter, end face, and chamfer.

[0024] However, in step S2, all specific machining steps must allow sufficient heat treatment deformation and grinding allowance in their machining dimensions.

[0025] S3, performance enhancement, is used to improve the fatigue strength and service life of plunger rings; Step S3 specifically includes: S31, heat treatment, involves a combination of quenching and high-temperature tempering to temper the plunger ring; this improves the material's hardness and toughness (HRC35~45), ensuring the plunger ring's mechanical properties while also mitigating the risk of later cracking. This is key to giving the plunger ring high hardness, high wear resistance, and high fatigue strength. The quenching parameters are as follows: heat to 830-860℃, hold for 10-15 minutes, and then quickly oil-cool or water-cool to obtain a martensitic structure; The high-temperature tempering parameters are as follows: 500-650℃, not less than three hours, followed by air cooling. The metallographic structure is grade 2-3. During tempering, martensite decomposes into a certain proportion of retained austenite and tempered cementite, thus reducing the hardness of the steel but increasing its toughness. Furthermore, different tempering temperatures and times will affect the mechanical properties of the steel. S32, shot peening, shot peening intensity 0.3mmA, coverage 200%, using a high-speed shot stream to impact the surface of the part, the purpose of which is to generate compressive stress on the surface, significantly improving the fatigue strength and service life of the part.

[0026] S4, Dimensional finishing, performs dimensional finishing on the enhanced plunger rings; Step S4 specifically includes: S41, end face grinding: Double end face grinding is adopted to ensure the parallelism and roughness of the two end faces.

[0027] S42, External cylindrical grinding: Using a high-precision grinding machine to machine internal holes and external diameters, controlling roundness, cylindricity, and the spherical diameter of the external cylindrical surface. This yields precise external cylindrical dimensions and allows for ultra-precision machining, which is one of the important mating dimensions.

[0028] S43, External Cylindrical Grinding Ultra-precision: Ultra-precision machining of the external cylindrical surface to remove grinding marks and achieve mirror-level roughness, which is the key to achieving a strict seal.

[0029] The precision of the outer spherical surface after ultra-precision reaches the micrometer level; the roughness of the outer circle after ultra-precision reaches within 0.1μm.

[0030] S5, Opening process, which is performed through the following steps: S51, A crack is machined at the inner diameter of the plunger ring, the crack extends from the inner diameter of the plunger ring toward the outer diameter, and the crack does not reach the outer diameter of the plunger ring. The slit in step S51 is formed by electro-pulse forming and has a V-shaped groove in cross-section, with the tip of the V-shaped groove facing the outer diameter of the plunger ring. The included angle formed by the opening of the V-shaped groove is 30°, and the groove depth from the opening of the V-shaped groove to its tip is 38-40% of the difference between the outer diameter and the inner diameter of the plunger ring.

[0031] S52, apply an outwardly expanding torque from the inner diameter of the plunger ring to create a fracture gap connecting the bottom of the crack to the outer diameter of the plunger ring. Step S52 involves passing a truncated cone through the inner diameter of the plunger ring to create a gap between the bottom of the crack and the outer diameter of the plunger ring. The width of this gap is less than one-sixth of the difference between the outer and inner diameters of the plunger ring. The outer diameter of one end face of the truncated cone is 0.03-0.05 mm smaller than the inner diameter of the plunger ring, while the outer diameter of the other end face is 0.13-0.15 mm larger than the inner diameter of the plunger ring. The taper of the truncated cone is 1:200-1:250.

[0032] S6, surface hardening treatment, the plunger ring is nitrided, and a nitrided layer with extremely high hardness is formed on the surface after the treatment, with a product hardness of HV800 or above.

[0033] S7, Post-processing of finished products, is used to ensure the usability, quality reliability and storage and transportation safety of finished products.

[0034] In this embodiment, the plunger ring is as follows: Figure 1-3 As shown, the diameter of its outer diameter surface is not exactly the same, but is an arc surface with the highest point on one side end face. Therefore, the outer diameters of the two end faces of the plunger ring are not the same, with one being larger and the other smaller.

[0035] Step S7 specifically includes: S71, Marking Installation Face: The most crucial and important function of the marking face is to indicate the installation direction of the plunger ring. It also helps distinguish different models and prevents incorrect installation.

[0036] S72, Quality Inspection: Dimensional Inspection: Checking whether the dimensions are qualified; S73, Elasticity test: Expand the plunger ring to the installation size and see if it can rebound in a short time and whether the crack size meets the drawing requirements; S74, Light Leakage Test: Place the ring in a standard gauge cylinder, illuminate one side of it, and observe the degree of light leakage on the other side. The light leakage gap must not exceed the specified value, and the total length of light leakage must not exceed a certain proportion of the circumference.

[0037] S75, Cleaning, Rust Prevention, and Packaging: After passing inspection, thoroughly clean the product, apply rust-preventive oil, and vacuum pack it to prevent rust and contamination during transportation and storage.

[0038] The above embodiments are merely one preferred embodiment of the present invention. Ordinary variations and substitutions made by those skilled in the art within the scope of the technical solution of the present invention are all included within the protection scope of the present invention.

Claims

1. A plunger ring machining process, implemented according to the following steps: S1, blank preparation, used to make ring-shaped blanks; S2, rough machining of dimensions, rough machining of the ring blank; S3, performance enhancement, is used to improve the fatigue strength and service life of plunger rings; S4, Dimensional finishing, performs dimensional finishing on the enhanced plunger rings; S5, Opening process, which is performed through the following steps: S51, A crack is machined at the inner diameter of the plunger ring, the crack extends from the inner diameter of the plunger ring toward the outer diameter, and the crack does not reach the outer diameter of the plunger ring. S52, apply an outwardly expanding torque from the inner diameter of the plunger ring to create a fracture gap connecting the bottom of the crack to the outer diameter of the plunger ring; S6, surface hardening treatment, used to improve the wear resistance and corrosion resistance of plunger rings; S7, Post-processing of finished products, is used to ensure the usability, quality reliability and storage and transportation safety of finished products.

2. The plunger ring processing technology according to claim 1, characterized in that: The crack in step S51 has a V-shaped groove in cross-section, and the tip of the V-shaped groove is set towards the outer diameter of the plunger ring.

3. The plunger ring processing technology according to claim 2, characterized in that: The included angle formed by the V-shaped groove opening is 30°, and the groove depth from the V-shaped groove opening to its tip is 38-40% of the difference between the outer diameter and the inner diameter of the plunger ring.

4. The plunger ring processing technology according to claim 2, characterized in that: The crack in step S51 is formed by electrical pulse molding.

5. The plunger ring processing technology according to claim 1, characterized in that: The width of the break is less than one-sixth of the difference between the outer and inner diameters of the plunger ring.

6. The plunger ring processing technology according to claim 5, characterized in that: In step S52, a truncated cone is passed through the inner diameter of the plunger ring to create a fracture between the bottom of the crack and the outer diameter of the plunger ring. The outer diameter of one end face of the truncated cone is smaller than the inner diameter of the plunger ring, and the outer diameter of the other end face is larger than the inner diameter of the plunger ring.

7. The plunger ring processing technology according to claim 6, characterized in that: The outer diameter of one end face of the truncated cone is 0.03-0.05 mm smaller than the inner diameter of the plunger ring, and the outer diameter of the other end face is 0.13-0.15 mm larger than the inner diameter of the plunger ring. The taper of the truncated cone is 1:200-1:

250.

8. The plunger ring processing technology according to claim 1, characterized in that: The S3 step is implemented through the following steps: S31, heat treatment, the plunger ring is quenched and tempered by a combination of quenching and high-temperature tempering. The quenching parameters are as follows: heat to 830-860℃, hold for 10-15 minutes, and then quickly oil-cool or water-cool to obtain martensitic structure. The high-temperature tempering parameters are as follows: 500-650℃, not less than three hours, and then air-cool. S32, shot peening, shot peening intensity 0.3mmA, coverage 200%, using high-speed shot stream to impact the surface of the part.

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