A plunger processing method, a plunger and a plunger pump

Abstract

The present invention relates to the field of plunger pump processing. Specifically, it relates to a plunger processing method, a plunger, and a plunger pump. The plunger processing method includes: after the positioning of the plunger on the turning equipment is completed, turning the end of the plunger located at a preset turning position until an annular curved surface and an annular cutting surface are formed at the end of the plunger; after the processing of the annular curved surface and the annular cutting surface is completed, performing heat treatment on the plunger; after the heat treatment is completed, performing cryogenic treatment on the plunger; after the cryogenic treatment is completed, grinding the outer circumferential surface of the plunger until the cross-sectional line of the outer circumferential surface of the plunger in the reference cross-section is located on the target cross-sectional line; after the grinding is completed, deburring the plunger. The plunger is applied to the above-mentioned plunger processing method. The plunger pump includes the above-mentioned plunger. In this way, the problem that the end fillet is severely damaged after the plunger processing is completed, resulting in sharp edges that are still prone to scratching the plunger hole wall is solved.

Description

Technical Field

[0001] The present invention relates to the field of plunger pump processing, and more particularly, to a method for processing a plunger, a plunger, and a plunger pump. Background Art

[0002] As the core moving part of a plunger pump, the machining quality of the outer circumferential surface and fillet of the plunger directly affects the sealing performance and service life of the plunger pump. In the traditional plunger machining process, the fillet of the plunger is generally turned first. After heat treatment to eliminate internal stress, in order to compensate for the slight deformation after heat treatment, the outer circumferential surface is then ground.

[0003] However, this process has significant defects: before grinding the outer circumferential surface, the fillet is tangent to the unground outer circumferential surface. After finishing machining the plunger, that is, grinding the outer circumferential surface, the end fillet is also damaged to a large extent, resulting in an incomplete fillet and no longer being tangent to the outer circumferential surface, and a sharp microscopic edge will be formed at the junction. The edge will scratch the plunger hole wall when the plunger moves back and forth at high speed, exacerbate the wear of the mating surface and cause hydraulic oil leakage, affecting the service life of the plunger pump. Therefore, there is an urgent need for a machining method that can improve the situation where the fillet of the plunger is damaged and the formed edge is easy to scratch the plunger hole wall. Summary of the Invention

[0004] To solve the problem that the end fillet of the plunger is damaged to a large extent after machining and the formed sharp edge is still easy to scratch the plunger hole wall, the present invention provides a method for processing a plunger, a plunger, and a plunger pump.

[0005] In a first aspect, the present invention provides a method for processing a plunger, the method for processing the plunger comprising:

[0006] Step S10, based on the plunger being positioned on a turning device and one end of the plunger being located at a preset turning position, turning the end of the plunger located at the preset turning position until an annular curved surface and an annular cutting surface are formed at the end of the plunger; the annular curved surface is convex; the annular cutting surface is connected to the annular curved surface; the annular curved surface is located in the extending direction of the annular cutting surface towards the end of the plunger at the preset turning position; the annular curved surface and the annular cutting surface are smoothly transitioned; the reference section passes through the axis of the plunger; the section line of the annular curved surface in the reference section is a curve;

[0007] Step S20, based on the completion of machining of the annular curved surface and the annular cutting surface, performing heat treatment on the plunger;

[0008] Step S30, based on the completion of the heat treatment, performing cryogenic treatment on the plunger;

[0009] Step S40: Based on the completion of the cryogenic treatment, grind the outer circumferential surface of the plunger until the section line of the outer circumferential surface of the plunger in the reference section is located at the target section line; in the state where the grinding is completed, the extension line of the section line of the annular curved surface in the reference section is tangent to the target section line at a first tangent point.

[0010] Step S50: Based on the completion of the grinding, deburr the plunger.

[0011] In some embodiments, the section line of the annular curved surface in the reference section is an arc line.

[0012] In some embodiments, the annular section is a conical surface; the diameter of the annular section gradually increases in a direction away from the annular curved surface.

[0013] In some embodiments, the section line of the annular section in the reference section is a straight line.

[0014] In some embodiments, the section line of the annular section in the reference section is tangent to the section line of the annular curved surface in the reference section at a second tangent point.

[0015] In some embodiments, step S10 includes steps S11 to S13;

[0016] Step S11: Based on the completion of the positioning of the plunger on the turning equipment and one end of the plunger being located at a preset turning position, obtain the cutting accuracy of the turning equipment.

[0017] Step S12: Based on the cutting accuracy, obtain turning parameters.

[0018] Step S13: Based on the turning parameters, turn the end of the plunger located at the preset turning position until an annular curved surface and an annular section are formed; the annular curved surface is convex; the annular section is connected to the annular curved surface; the annular curved surface is located in the extending direction of the annular section towards the end of the plunger at the preset turning position; the reference section passes through the axis of the plunger; the turning parameters include the distance value from the second tangent point to the target section line; the distance value is greater than 1 times the cutting accuracy and less than 2 times the cutting accuracy.

[0019] In some embodiments, the turning parameters further include the diameter of the plunger before grinding and the arc radius of the section line of the annular curved surface in the reference section; the arc radius of the section line of the annular curved surface in the reference section is equal to 5% - 10% of the diameter of the plunger before grinding.

[0020] In some embodiments, the turning parameters further include the angle between the sectional line of the annular section in the reference section and the plunger axis; the angle is 3° to 6°.

[0021] In some embodiments, step S40 includes:

[0022] Step S41, based on the completion of the cryogenic treatment, repeating steps S10 to S30 to process the other end of the plunger;

[0023] Step S42, based on the completion of the processing of both ends of the plunger, grinding the outer circumferential surface of the plunger until the sectional line of the outer circumferential surface of the plunger in the reference section is located at the target sectional line; in the state where the grinding is completed, the extension line of the sectional line of the annular curved surface in the reference section is tangent to the target sectional line at a first tangent point.

[0024] In some embodiments, the plunger processing method further includes:

[0025] Step S70, based on the completion of deburring, performing oilstone superfinishing on the plunger until crosshatch patterns are formed on the outer circumferential surface of the plunger.

[0026] In a second aspect, the present invention provides a plunger, which is applied to any of the plunger processing methods in the first aspect. The plunger includes a plunger rod and a ball head; the plunger rod and the ball head are integrally formed; each end of the plunger rod has an annular section and an annular curved surface; the annular curved surface is convex; the annular section is connected to the annular curved surface; the annular section is located in the extending direction of the annular curved surface toward the other end of the plunger; the annular curved surface and the annular section are smoothly transitioned; the reference section passes through the axis of the plunger; the sectional line of the annular curved surface in the reference section is a curve; the extension line of the sectional line of the annular curved surface in the reference section is tangent to the sectional line of the outer circumferential surface of the plunger rod in the reference section at a first tangent point.

[0027] In a third aspect, the present invention provides a plunger pump, which includes the plunger in the second aspect.

[0028] To solve the problem that the end fillets of the plunger are severely damaged after processing and sharp edges are still likely to scratch the plunger hole wall, the present invention has the following advantages:

[0029] In view of the situation that the processing sequence cannot be changed and the fillet needs to be processed first and then the outer circumference is ground, and the fillet will be damaged during the grinding process, the method of changing the connection between the fillet and the outer circumference of the plunger is adopted, and a section of annular section is added between the fillet and the outer circumference, so that the fillet is not damaged when the outer circumference is ground, and the annular section becomes the transition section between the fillet and the outer circumference. In addition, the contour extension line of the fillet is made tangent to the outer circumference after grinding, so that a better smooth transition between the outer circumference, the annular section and the fillet can be achieved, which greatly improves the smoothness of the plunger end and avoids scratching the plunger hole wall as much as possible. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 A schematic flow chart of a plunger processing method according to an embodiment is shown;

[0031] Figure 2 A schematic diagram of a plunger of an embodiment is shown;

[0032] Figure 3 A schematic diagram of plunger processing according to an embodiment is shown, wherein the dotted line represents the portion to be processed;

[0033] Figure 4 Shows Figure 3 A partial enlarged view of the circled part.

[0034] Reference numerals: 10 plunger; 11 ball head; 12 plunger rod; 121 annular curved surface; 122 annular section; 123 target section line; 124 first tangent point; 125 second tangent point. DETAILED DESCRIPTION

[0035] The present disclosure will now be discussed with reference to several exemplary embodiments. It should be understood that these embodiments are discussed only to enable those skilled in the art to better understand and thus implement the present disclosure, rather than implying any limitation on the scope of the present disclosure.

[0036] As used herein, the term "comprising" and its variants are to be construed as open-ended terms meaning "including but not limited to". The term "based on" is to be construed as "at least partially based on". The terms "one embodiment" and "an embodiment" are to be construed as "at least one embodiment". The term "another embodiment" is to be construed as "at least one other embodiment". The orientation or positional relationship indicated by the terms "upper", "lower", "left", "right", "front", "rear", "top", "bottom", "inner", "outer", "vertical", "horizontal", "lateral", "longitudinal", etc. is based on the orientation or positional relationship shown in the drawings. These terms are mainly used to better describe the present application and its embodiments, and are not used to limit that the indicated devices, elements or components must have a specific orientation, or be constructed and operated in a specific orientation. Also, in addition to being able to represent the orientation or positional relationship, some of the above terms may also be used to represent other meanings. For example, the term "upper" may also be used to represent a certain attachment relationship or connection relationship in some cases. For those of ordinary skill in the art, the specific meanings of these terms in the present application can be understood according to the specific circumstances. In addition, the terms "mounted", "arranged", "provided with", "connected", "coupled" should be understood in a broad sense. For example, it may be a fixed connection, a detachable connection, or an integral structure; it may be a mechanical connection or an electrical connection; it may be directly connected, or indirectly connected through an intermediate medium, or there may be internal communication between two devices, elements or components. For those of ordinary skill in the art, the specific meanings of the above terms in the present application can be understood according to the specific circumstances. In addition, the terms "first", "second", etc. are mainly used to distinguish different devices, elements or components (the specific types and structures may be the same or different), and are not used to indicate or imply the relative importance and quantity of the indicated devices, elements or components. Unless otherwise specified, the meaning of "a plurality of" is two or more.

[0037] In the traditional processing technology of the plunger 10, the fillet of the plunger 10 is often turned first. After heat treatment to eliminate internal stress, in order to make up for the slight deformation after heat treatment, the outer circumferential surface is then ground. The fillet is tangent to the outer circumferential surface of the plunger 10 before grinding, so that the outer circumferential surface after grinding is not tangent to the fillet, forming an incomplete arc, and the edge is relatively obvious, which is likely to scratch the wall of the plunger hole and affect the service life of the plunger pump. In this embodiment, a method for processing the plunger 10 is provided. As Figure 1 shown, the method for processing the plunger 10 includes steps S10 to S50, and the details of each step are described as follows:

[0038] Step S10, based on the completion of the positioning of the plunger 10 on the turning equipment, and one end of the plunger 10 is located at the preset turning position, the end of the plunger 10 located at the preset turning position is turned until an annular surface 121 and an annular section 122 are formed at the end of the plunger 10. The annular surface 121 is convex. The annular section 122 is connected to the annular surface 121. The annular surface 121 is located in the extension direction of the annular section 122 toward the end of the plunger 10 at the preset turning position, and the annular surface 121 and the annular section 122 are smoothly transitioned. Among them, the smooth transition can include tangency and near tangency, and tangency is the best solution, which can maximize the degree of smooth transition. The reference section passes through the axis of the plunger 10. The section line of the annular surface 121 in the reference section is a curve, which can be a circular arc, an elliptical arc, etc.

[0039] Step S20, based on the completion of the processing of the annular curved surface 121 and the annular section 122, the plunger 10 is heat treated to improve the hardness, strength and toughness of the material, eliminate the internal stress generated during the processing, and further improve the overall performance and service life of the plunger 10.

[0040] Step S30, based on the completion of the heat treatment, the plunger 10 is subjected to a cold treatment, which can further optimize the microstructure of the material, improve the stability and wear resistance of the material, and reduce the content of residual austenite in the material after the heat treatment.

[0041] Step S40, based on the completion of the ice-cold treatment, the outer circumferential surface of the plunger 10 is ground until the section line of the outer circumferential surface of the plunger 10 in the reference section is located at the target section line 123. During the grinding process, the portion of the annular section 122 located outside the target section line 123 in the reference section is removed. Figure 4 As shown, when grinding is completed, the extension line of the section line of the annular surface 121 in the reference section is tangent to the target section line 123 at the first tangent point 124, which can ensure a smooth transition from the outer circumferential surface to the annular surface 121, so that the transition area is not easy to scratch the plunger hole wall.

[0042] Step S50, based on the completion of grinding, the plunger 10 is deburred to ensure the smoothness of the outer surface of the plunger 10. Due to the difference in precision between turning and grinding, it is difficult to fine-tune the end fillet, that is, the annular curved surface 121, to be tangent to the outer circumferential surface. Therefore, the present invention makes the outer circumferential surface and the annular curved surface 121 close to tangent and can smoothly transition within the difference range of the machining precision between grinding and turning through the transition of the annular cut surface 122. The smoothness of the end of the plunger 10 is greatly improved, and scratches on the plunger hole wall are avoided as much as possible.

[0043] In this embodiment, if Figure 2 As shown, the cross-sectional line of the annular curved surface 121 in the reference cross section is an arc line, such asFigure 4 As shown, the extension line of the arc line is tangent to the target section line 123 at the first tangent point 124, so that a better smooth transition from the outer circumferential surface to the annular curved surface 121 can be ensured. At the same time, the arc line can be tangent or nearly tangent to the section line of the annular section plane 122 in the reference section, making the transition area between the annular curved surface 121 and the outer circumferential surface not easily scratch the wall of the plunger hole. In another embodiment, the section line of the annular curved surface 121 in the reference section can be other arcs, such as elliptical arcs, etc.

[0044] In this embodiment, as Figure 3 shown, the annular section plane 122 is a conical surface, and the diameter of the annular section plane 122 gradually increases in the direction away from the annular curved surface 121. Compared with the stepped surface, the use of a conical surface for the annular section plane 122 has a smoother transition, is not easily scratched on the wall of the plunger hole, and can allow a certain amount of turning and grinding processing errors.

[0045] In this embodiment, as Figure 4 shown, the section line of the annular section plane 122 in the reference section is a straight line, and the straight line is more convenient for processing than the arc line, improving the yield rate.

[0046] In this embodiment, as Figure 4 shown, the section line of the annular section plane 122 in the reference section is tangent to the section line of the annular curved surface 121 in the reference section at the second tangent point 125. The tangency between the annular section plane 122 and the annular curved surface 121 can achieve the best smooth transition, making it not easy to scratch the hole wall when the plunger 10 slides in the plunger hole.

[0047] In this embodiment, step S10 includes steps S11 to S13, and the details of each step are as follows:

[0048] Step S11, based on the fact that the positioning of the plunger 10 on the turning equipment is completed and one end of the plunger 10 is located at the preset turning position, obtain the cutting accuracy of the turning equipment. The cutting accuracy of the equipment determines the dimensional accuracy, geometric accuracy, and surface quality of the machining.

[0049] Step S12, based on the cutting accuracy, obtain the turning parameters.

[0050] Step S13: Based on the turning parameters, turn the end of the plunger 10 at the preset turning position until the annular curved surface 121 and the annular cutting surface 122 are formed. The annular curved surface 121 is convex, and the annular cutting surface 122 is connected to the annular curved surface 121. The annular curved surface 121 is located in the extending direction of the plunger 10's end towards the preset turning position of the annular cutting surface 122. The reference section passes through the axis of the plunger 10. The turning parameters include the distance value from the second tangent point 125 to the target section line 123. The distance value is greater than 1 times the cutting accuracy and less than 2 times the cutting accuracy. The distance value can be 1μm, 2μm, 3μm, etc. According to the turning parameters, the tangent point position of the annular cutting surface 122 and the annular curved surface 121 can be determined. The size of the distance value can ensure the position accuracy of the second tangent point 125 during the finish machining of the outer circumferential surface, thereby ensuring the smooth transition between the annular cutting surface 122 and the annular curved surface 121.

[0051] In this embodiment, the turning parameters further include the diameter of the plunger 10 before grinding and the arc radius of the section line of the annular curved surface 121 in the reference section. According to these parameters, the annular curved surface 121 can be machined. The arc radius of the section line of the annular curved surface 121 in the reference section is equal to 5% - 10% of the diameter of the plunger 10 before grinding. A high-precision seal is required for the fit between the plunger 10 and the plunger hole. A smaller fillet can avoid the problem of seal failure caused by an overly large fillet. In addition, a smaller fillet simplifies the machining process of the plunger 10 compared to a larger fillet.

[0052] In this embodiment, the turning parameters further include the angle between the section line of the annular cutting surface 122 in the reference section and the axis of the plunger 10. According to the size of the angle and the distance value from the second tangent point 125 to the target section line 123, the annular cutting surface 122 can be machined. The angle is 3° - 6°, so that it can be tangent to the annular curved surface 121. In addition, a smaller angle can also make the annular curved surface 121 closer to parallel with the outer circumferential surface of the plunger 10, making the transition between the outer circumferential surface and the annular cutting surface 122 smoother and reducing the damage suffered by the plunger 10 when moving between the plunger holes.

[0053] In this embodiment, step S40 includes steps S41 - S42, which are described in detail as follows:

[0054] Step S41: Based on the completion of cryogenic treatment, repeat steps S10 to S30 to machine the other end of the plunger 10, making both ends of the plunger 10 rod rounded, so that the sliding fit between the plunger 10 and the plunger hole is smoother.

[0055] Step S42. Based on the completion of the machining at both ends of the plunger 10, the outer circumferential surface of the plunger 10 is ground until the section line of the outer circumferential surface of the plunger 10 in the reference section is located at the target section line 123. At this time, most of the volume of the annular section 122 is ground away, and a small remaining part is tangent to the annular curved surface 121 at the second tangent point 125. In the state after the grinding is completed, the extension line of the section line of the annular curved surface 121 in the reference section is tangent to the target section line 123 at the first tangent point 124. Thus, a smooth transition of the outer circumferential surface, the annular section 122, and the annular curved surface 121 can be achieved, so that the transition area is not easily scratched on the wall of the plunger hole when the plunger 10 slides in the plunger hole.

[0056] In this embodiment, the machining method of the plunger 10 further includes:

[0057] Step S70. Based on the completion of deburring, the plunger 10 is processed by an oilstone superfinishing machine until cross-hatched patterns are formed on the outer circumferential surface of the plunger 10. These patterns have both flat surfaces and concave grooves. The concave grooves can make the lubricant evenly adhere to the surface of the part, while the flat surfaces provide a relatively high proportion of contact surfaces, which can increase the service life of the friction pair and improve the sealing performance while reducing friction.

[0058] In this embodiment, as Figure 2 shown, the plunger 10 includes a plunger rod 12 and a ball head 11. The plunger rod 12 and the ball head 11 are integrally formed. Each end of the plunger rod 12 has an annular section 122 and an annular curved surface 121. The annular curved surface 121 is convex. The annular section 122 is connected to the annular curved surface 121. The annular section 122 is located in the extending direction of the annular curved surface 121 toward the other end of the plunger 10. The annular curved surface 121 and the annular section 122 are smoothly transitioned. Preferably, the annular curved surface 121 can be tangent to the annular section 122. The reference section passes through the axis of the plunger 10. The section line of the annular curved surface 121 in the reference section is a curve, and the extension line of the section line of the annular curved surface 121 in the reference section is tangent to the section line of the outer circumferential surface of the plunger rod 12 in the reference section at the first tangent point 124. A relatively smooth transition can be achieved among the outer circumferential surface of the plunger 10, the annular section 122, and the annular curved surface 121, so that the transition area is not easily scratched on the wall of the plunger hole when the plunger 10 slides in the plunger hole.

[0059] In this embodiment, the plunger pump includes the plunger 10 in the above embodiment. There can be multiple plungers 10, and the multiple plungers 10 can be slidably matched with multiple plunger holes.

[0060] Those of ordinary skill in the art can understand that the above embodiments are specific cases for implementing the present disclosure, and in practical applications, various changes can be made in form and details without departing from the scope of the present disclosure.

Claims

1. A plunger processing method, characterized in that: The plunger processing method comprises: Step S10, based on the plunger being positioned on the turning equipment and one end of the plunger being located at a preset turning position, turning the end of the plunger located at the preset turning position until an annular surface and an annular section are formed at the end of the plunger; the annular surface is convex; the annular section is connected with the annular surface; the annular surface is located in the extension direction of the annular section toward the end of the plunger at the preset turning position; the annular surface and the annular section have a smooth transition; the reference section passes through the axis of the plunger; the section line of the annular surface in the reference section is a curve; Step S20, based on the completion of machining of the annular curved surface and the annular section, heat treating the plunger; Step S30, based on the completion of the heat treatment, performing a cooling treatment on the plunger; Step S40, based on the completion of the ice-cold treatment, grinding the outer circumferential surface of the plunger until the section line of the outer circumferential surface of the plunger in the reference section is located at the target section line; in the state where the grinding is completed, the extension line of the section line of the annular surface in the reference section is tangent to the target section line at a first tangent point; Step S50, deburring the plunger based on the grinding being completed.

2. A plunger processing method according to claim 1, characterized in that: The cross-sectional line of the annular curved surface in the reference cross-section is an arc line.

3. A plunger processing method according to claim 2, characterized in that: The annular section is a conical surface; the diameter of the annular section gradually increases in a direction away from the annular curved surface.

4. A plunger processing method according to claim 3, characterized in that: The cross-sectional line of the annular section in the reference cross-sectional area is a straight line.

5. A plunger processing method according to claim 4, characterized in that: The cross-sectional line of the annular section in the reference cross-sectional area is tangent to the cross-sectional line of the annular curved surface in the reference cross-sectional area at a second tangent point.

6. A plunger processing method according to claim 5, characterized in that: The step S10 includes steps S11 to S13; Step S11, based on the plunger being positioned on the turning device and one end of the plunger being located at a preset turning position, obtaining the cutting accuracy of the turning device; Step S12, obtaining turning parameters based on the cutting accuracy; Step S13, based on the turning parameters, turning the end of the plunger located at the preset turning position until an annular curved surface and an annular cross-section are formed; the annular curved surface is convex; The annular section is connected to the annular curved surface; the annular curved surface is located in the extension direction of the end of the plunger of the annular section toward the preset turning position; the reference section passes through the axis of the plunger; The turning parameters include a distance value from the second tangent point to the target cross-sectional line; the distance value is greater than 1 times the cutting accuracy and less than 2 times the cutting accuracy.

7. A plunger processing method according to claim 6, characterized in that: The turning parameters also include the diameter of the plunger before grinding and the arc radius of the cross-sectional line of the annular surface in the reference cross-sectional area; the arc radius of the cross-sectional line of the annular surface in the reference cross-sectional area is equal to 5% to 10% of the diameter of the plunger before grinding.

8. A plunger processing method according to claim 6, characterized in that: The turning parameters also include an angle between a section line of the annular section in the reference section and the plunger axis; the angle is 3° to 6°.

9. A plunger processing method according to claim 1, characterized in that: The step S40 comprises: Step S41, based on the completion of the ice-cold treatment, repeating the steps S10 to S30 to process the other end of the plunger; Step S42, based on the completion of processing at both ends of the plunger, the outer circumferential surface of the plunger is ground until the section line of the outer circumferential surface of the plunger in the reference section is located at the target section line; when the grinding is completed, the extension line of the section line of the annular surface in the reference section is tangent to the target section line at the first tangent point.

10. A plunger processing method according to claim 1, characterized in that: The plunger processing method also includes: Step S70, based on the completion of the deburring, the plunger is subjected to oilstone ultra-finishing machining until a cross-net pattern is formed on the outer circumferential surface of the plunger.

11. A plunger, characterized in that: Processed by the plunger processing method described in any one of claims 1 to 10; The plunger comprises a plunger rod and a ball head; the plunger rod and the ball head are integrally formed; each end of the plunger rod has an annular section and an annular curved surface; the annular curved surface is convex; the annular section is connected with the annular curved surface; The annular section is located in the extension direction of the annular curved surface toward the other end of the plunger; the annular curved surface and the annular section have a smooth transition; The reference section passes through the axis of the plunger; The cross-sectional line of the annular curved surface in the reference cross-sectional area is a curve; the extension line of the cross-sectional line of the annular curved surface in the reference cross-sectional area is tangent to the cross-sectional line of the outer circumferential surface of the plunger rod in the reference cross-sectional area at a first tangent point.

12. A plunger pump, characterized in that: The plunger pump comprises the plunger as claimed in claim 11.

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