Machining method of rotor plunger hole

Abstract

The invention relates to the technical field of plunger pump machining, in particular to a machining method for a rotor plunger hole. The processing method comprises the steps from S10 to S40. The machining method comprises the following steps: manufacturing a semi-finished rotor, and positioning the semi-finished rotor at a milling station; performing rough machining on each reference plunger hole in sequence through a first milling cutter to form a first machining hole; sequentially carrying out semi-finish machining on each first machining hole through a second milling cutter to form a second machining hole; then, finish machining is conducted on the second machining holes in sequence through a third milling cutter to form the formed plunger holes; the milling allowance of the finish machining in the radial direction of the second machining hole is larger than the milling allowance of the semi-finish machining in the radial direction of the first machining hole. In this way, the machining precision is improved while the hole wall roughness precision grade of the rotor plunger hole is reduced, and therefore the diffusion welding quality of the plunger hole wall and the copper bush can be improved.

Description

Technical Field

[0001] The present invention relates to the technical field of plunger pump processing, and in particular, to a processing method for rotor plunger holes. Background Art

[0002] A plunger pump is a common hydraulic pump, and its core components include a rotor, a plunger rod, and a plunger hole. The rotor has a plurality of radially or axially distributed plunger holes for accommodating the plunger rod. The plunger rod is usually cylindrical, one end is connected to the rotor, and the other end slides in the plunger hole. The rotor, the plunger rod, and the plunger hole work together. The rotation of the rotor drives the reciprocating movement of the plunger rod, and the plunger rod slides in the plunger hole to achieve the suction and discharge of liquid.

[0003] However, with the iteration of plunger pumps, the process dimension requirements for the plunger hole system of the rotor assembly, which is a core part, have been gradually increased. After the plunger hole system is processed, it needs to be diffusion-welded with a copper bushing to enhance the durability of the plunger hole. The dimensional accuracy, hole system consistency, surface roughness, etc. of the plunger hole processing may all affect the processing quality of subsequent processes. Currently, the diffusion welding quality between the rotor and the copper bushing needs to be further optimized to improve the performance of the plunger pump. Summary of the Invention

[0004] To solve the problem that the diffusion welding quality between the rotor plunger hole and the copper bushing needs to be further improved, the present invention provides a processing method for rotor plunger holes, including: Step S10, based on the completion of manufacturing the rotor semi-finished product, positioning the rotor semi-finished product at the milling station; the rotor semi-finished product includes a rotor body; the rotor body has a plurality of reference plunger holes; the depth of the reference plunger holes is less than the axial thickness of the rotor body; the plurality of reference plunger holes are evenly distributed around the axis of the rotor body; the diameter of the reference plunger holes is less than the diameter of the formed plunger holes; Step S20, based on the completion of positioning the rotor semi-finished product at the milling station, rough machining each of the reference plunger holes in sequence with a first milling cutter to form a first processed hole; the first milling cutter is a tapered milling cutter; when the first milling cutter is in a state of waiting for feed outside the reference plunger hole, the end diameter of the first milling cutter facing the rotor semi-finished product is greater than the end diameter of the first milling cutter away from the rotor semi-finished product; the diameter of the first processed hole is greater than the diameter of the reference plunger hole and less than the diameter of the formed plunger hole; Step S30, based on the completion of the rough machining, each of the first machining holes is sequentially semi-finished by a second milling cutter to form a second machining hole; the second milling cutter is a cylindrical milling cutter; the milling allowance in the radial direction of the reference plunger hole in the rough machining is greater than the milling allowance in the radial direction of the first machining hole in the semi-finishing; the diameter of the second machining hole is greater than the diameter of the first machining hole and less than the diameter of the formed plunger hole; Step S40, based on the completion of the semi-finishing, each of the second machining holes is sequentially finished by a third milling cutter to form the formed plunger hole; the third milling cutter is a tapered milling cutter; when the third milling cutter is in a state of waiting for feed outside the second machining hole, the end diameter of the third milling cutter facing the rotor semi-finished product is less than the end diameter of the third milling cutter away from the rotor semi-finished product; the milling allowance in the radial direction of the second machining hole in the finishing is greater than the milling allowance in the radial direction of the first machining hole in the semi-finishing; the milling allowance in the radial direction of the second machining hole in the finishing is less than the milling allowance in the radial direction of the reference plunger hole in the rough machining; when the finishing is completed, the formed plunger hole machining is completed.

[0005] In some embodiments, the milling allowance in the radial direction of the second machining hole in the finishing is 2 to 3 times the milling allowance in the radial direction of the first machining hole in the semi-finishing.

[0006] In some embodiments, the feed depth of the rough machining in the axial direction of the reference plunger hole is the upper limit of the hole depth tolerance during the machining of the reference plunger hole; the feed depth of the semi-finishing in the axial direction of the first machining hole is the upper limit of the hole depth tolerance during the machining of the first machining hole; the feed depth of the finishing in the axial direction of the second machining hole is the lower limit of the hole depth tolerance during the machining of the second machining hole.

[0007] In some embodiments, in step S20, the milling path of the first milling cutter in the rough machining is a spiral path; In step S30, the milling path of the second milling cutter in the semi-finishing is a spiral path; In step S40, the process of the finishing includes: first, moving the third milling cutter along the axial direction of the second machining hole to a preset depth, and then controlling the third milling cutter to mill the second machining hole along an arc path.

[0008] In some embodiments, step S40 includes: Step S41, based on the completion of the semi-finishing, each of the open ends of the second machining holes is sequentially chamfered by a fourth milling cutter; the milling path of the fourth milling cutter is an arc; Step S42, based on the completion of the chamfering machining, each of the second machining holes is sequentially finish-machined by a third milling cutter to form the formed plunger hole; the third milling cutter is a conical milling cutter; when the third milling cutter is in a state of waiting to feed outside the second machining hole, the diameter of the end of the third milling cutter facing the rotor semi-finished product is smaller than the diameter of the end of the third milling cutter away from the rotor semi-finished product; the milling allowance in the radial direction of the second machining hole during the finish machining is greater than the milling allowance in the radial direction of the first machining hole during the semi-finish machining; the milling allowance in the radial direction of the second machining hole during the finish machining is smaller than the milling allowance in the radial direction of the reference plunger hole during the rough machining; when the finish machining is completed, the machining of the formed plunger hole is completed.

[0009] In some embodiments, the chamfer radius of the second machining hole is greater than 2% - 5% of the radius of the formed plunger hole.

[0010] In some embodiments, the fourth milling cutter is an R corner milling cutter; the diameter of one end of the fourth milling cutter close to the second machining hole is 2 / 3 - 3 / 4 of the diameter of the formed plunger hole.

[0011] In some embodiments, the step S20 includes: Step S21, based on the completion of the positioning of the rotor semi-finished product at the milling station, each of the reference plunger holes is sequentially rough-machined by a first milling cutter with a first rough milling allowance according to a first milling sequence to form a first machining hole; the first rough milling allowance is the milling allowance in the radial direction of the reference plunger hole; Step S22, based on the occurrence of a first failure state when the first milling cutter rough-machines one of the reference plunger holes, the first failure state is repaired and eliminated; in the first failure state, the first milling cutter stops the rough machining; Step S23, based on the completion of the repair and elimination of the first failure state, the first milling cutter restarts and re-rough-machines the reference plunger hole at the fault shutdown position with a second rough milling allowance; the second rough milling allowance is the milling allowance in the radial direction of the reference plunger hole; the second rough milling allowance is smaller than the first rough milling allowance; Step S24, based on the completion of the rough machining of the reference plunger hole at the fault shutdown position, control the first milling cutter to sequentially rough-machine the subsequent reference plunger holes with the first rough milling allowance according to the first milling sequence.

[0012] In some embodiments, the step S30 includes: Step S31: Based on the completion of the rough machining, use a second milling cutter to semi-finish machine each of the first machining holes in sequence according to a second milling sequence with a first semi-finishing allowance; the first semi-finishing allowance is the milling allowance upward from the diameter of the first machining hole to form a second machining hole. Step S32: Based on the occurrence of a second failure state when the second milling cutter is semi-finishing one of the first machining holes, repair and eliminate the second failure state; in the second failure state, the second milling cutter stops the semi-finishing operation. Step S33: Based on the completion of the repair and elimination of the second failure state, restart the second milling cutter and start from the first machining hole at the fault shutdown position with a second semi-finishing allowance, and re-perform the semi-finishing operation in sequence according to the second milling sequence. Alternatively, based on the completion of the repair and elimination of the second failure state, restart the second milling cutter and re-perform the semi-finishing operation on each of the first machining holes in sequence according to the second milling sequence with a second semi-finishing allowance; the second semi-finishing allowance is greater than the first semi-finishing allowance; wherein, the second milling sequence is opposite to the first milling sequence.

[0013] In some embodiments, step S42 includes: Step S421: Based on the completion of the chamfering machining, use a third milling cutter to finish machine each of the second machining holes in sequence according to the first milling sequence with a first finishing allowance to obtain the formed plunger hole; the first finishing allowance is the milling allowance upward from the diameter of the second machining hole. Step S422: Based on the occurrence of a third failure state when the third milling cutter is finishing one of the second machining holes, repair and eliminate the third failure state; in the third failure state, the third milling cutter stops the finishing operation. Step S423: Based on the completion of the repair and elimination of the third failure state, restart the third milling cutter and re-perform the finishing operation on each of the second machining holes in sequence according to the first milling sequence with a second finishing allowance; the second finishing allowance is greater than the first finishing allowance.

[0014] To solve the problem that the diffusion welding quality between the rotor plunger hole and the copper bushing needs to be further improved, the present invention has the following advantages: The present invention adopts the method that the milling allowance for finish machining is larger than that for semi-finish machining, which can increase the milling vibration of the third milling cutter during finish machining, thereby improving the Ra value of the surface roughness of the formed plunger hole, that is, reducing the accuracy grade of the wall roughness of the rotor formed plunger hole, and further improving the diffusion welding quality between the plunger hole wall and the copper bushing. In addition, the present invention uses three different types of milling cutters, so that the plunger hole gradually presents a conical shape with an opening diameter larger than the bottom diameter or is close to a cylindrical shape during the machining process, meeting the requirements of diffusion welding. At the same time, the selection of the first milling cutter is completely opposite to the cone of the third milling cutter, so that more milling allowance can be reserved for semi-finish machining and finish machining after rough machining, which is more conducive to designing the milling allowance for finish machining to be larger than that for semi-finish machining. Description of the Drawings

[0015] Figure 1 The flowchart shows a method for machining a rotor plunger hole according to an embodiment; Figure 2 The schematic diagram shows the states before and after rough machining of a reference plunger hole in a method for machining a rotor plunger hole according to an embodiment; Figure 3 The schematic diagram shows the states before and after semi-finish machining in a method for machining a rotor plunger hole according to an embodiment; Figure 4 The schematic diagram shows the state after chamfering in a method for machining a rotor plunger hole according to an embodiment; Figure 5 The schematic diagram shows the states before and after finish machining in a method for machining a rotor plunger hole according to an embodiment.

[0016] Reference numerals: 10, rotor body; 11, reference plunger hole; 12, first machining hole; 13, second machining hole; 14, formed plunger hole; 20, first milling cutter; 30, second milling cutter; 40, third milling cutter. Detailed Embodiments

[0017] Now, the content of the present disclosure will be described with reference to several exemplary embodiments. It should be understood that these embodiments are described only to enable those of ordinary skill in the art to better understand and thus implement the content of the present disclosure, rather than implying any limitation on the scope of the present disclosure.

[0018] 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 "an embodiment" and "one 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. Moreover, in addition to being used 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 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 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.

[0019] The core components of a plunger pump include a rotor and a plunger rod. The rotor has a plurality of plunger holes distributed around its central axis, and the plunger holes are used to accommodate the plunger rod. The plunger rod is usually cylindrical, and one end of the plunger rod slides within the plunger hole. Since the plunger rod reciprocates frequently within the plunger hole, it is necessary to diffusion-weld a copper bushing within the plunger hole to improve durability. To improve the diffusion-welding quality between the plunger hole and the copper bushing, the dimensional accuracy and surface roughness of the plunger hole are particularly important. For this reason, some embodiments disclose a processing method for the plunger holes of a rotor. In some embodiments, as Figure 1 shown, the processing method for the plunger holes of a rotor includes: Step S10, based on the completion of manufacturing the rotor semi-finished product, position the rotor semi-finished product at the milling station. The way of positioning and fixing is not limited. As Figure 2As shown, the semi-finished rotor includes a rotor body 10. The rotor body 10 has a plurality of reference plunger holes 11. The depth of the reference plunger holes 11 is less than the axial thickness of the rotor body 10. The plurality of reference plunger holes 11 are evenly distributed around the axis of the rotor body 10. The diameter of the reference plunger holes 11 is less than the diameter of the formed plunger holes 14.

[0020] Step S20, based on the positioning of the semi-finished rotor at the milling station being completed, rough machining is sequentially performed on each reference plunger hole 11 by a first milling cutter 20 to form a first machining hole 12. As Figure 2 shown, the first milling cutter 20 is a tapered milling cutter. When the first milling cutter 20 is in a state of waiting to feed outside the reference plunger hole 11, the end diameter of the first milling cutter 20 facing the end of the semi-finished rotor is greater than the end diameter of the first milling cutter 20 away from the semi-finished rotor, that is, an inverted tapered milling cutter. The diameter of the first machining hole 12 is greater than the diameter of the reference plunger hole 11 and less than the diameter of the formed plunger hole 14. Since rough machining is high-load milling to remove the allowance, the tool wears quickly, the cutting resistance of the tool tip is large, and a more firm and stable tool tip structure is required. Therefore, the first milling cutter 20 is selected as a tapered milling cutter. Compared with a cylindrical milling cutter, the first milling cutter 20 can reduce tool deflection during high-load milling, enhance the strength of the tool, and reduce the risk of damage such as tool breakage during cutting, thereby ensuring the processing efficiency and increasing the service life of the tool. The shape of the tapered milling cutter itself matches the tapered hole. When machining the tapered hole, the tapered hole can be directly machined in one go by spiral milling, without the need for complex programming or multiple machining to form the taper as when using a cylindrical milling cutter. Even if there is a tool deflection phenomenon due to a large rough machining milling allowance, the first machining hole 12 will be close to a weak inverted taper, that is, close to the outer contour shape of the first milling cutter 20.

[0021] Step S30, based on the completion of rough machining, semi-finishing is sequentially performed on each first machining hole 12 by a second milling cutter 30 to form a second machining hole 13. As Figure 3 shown, the second milling cutter 30 is a cylindrical milling cutter. The milling allowance in the radial direction of the reference plunger hole 11 during rough machining is greater than the milling allowance in the radial direction of the first machining hole 12 during semi-finishing. The diameter of the second machining hole 13 is greater than the diameter of the first machining hole 12 and less than the diameter of the formed plunger hole 14.

[0022] Step S40, based on the completion of semi-finishing, finishing is sequentially performed on each second machining hole 13 by a third milling cutter 40 to form the formed plunger hole 14. As Figure 5As shown, the third milling cutter 40 is a conical milling cutter. When the third milling cutter 40 is in a state of waiting for feed outside the second machining hole 13, the diameter of the end of the third milling cutter 40 facing the semi-finished rotor is smaller than the diameter of the end of the third milling cutter 40 away from the semi-finished rotor, that is, a positive conical milling cutter. The machining allowance in the radial direction of the second machining hole 13 for finish machining is greater than the machining allowance in the radial direction of the first machining hole 12 for semi-finish machining. The machining allowance in the radial direction of the second machining hole 13 for finish machining is smaller than the machining allowance in the radial direction of the reference plunger hole 11 for rough machining. In the state where the finish machining is completed, the formed plunger hole 14 is machined. Since the machining allowance for finish machining is greater than that for semi-finish machining, the vibration amount of the tool in the high-load milling state during finish machining will be greater than that of the tool during semi-finish machining, resulting in a higher Ra value of the inner wall surface roughness of the formed plunger hole 14, that is, reducing the hole wall roughness accuracy grade of the formed plunger hole 14, which is convenient for improving the quality during the diffusion welding of the formed plunger hole 14 and the copper bushing.

[0023] Since the plunger hole needs to be designed as a cylinder or a positive cone to achieve the press-fitting of the copper bushing, that is, the diameter of the open end of the plunger hole is greater than the diameter of the bottom of the plunger hole, the present invention uses an inverted conical first milling cutter 20 to make the first machining hole 12 after rough machining approach a weak inverted cone, so that there is a certain difference in the contour shape between the first machining hole 12 and the formed plunger hole 14, resulting in a large difference in the dimensions between the first machining hole 12 and the formed plunger hole 14. Furthermore, it is convenient to reasonably design the machining allowance for finish machining to be greater than that for semi-finish machining to ensure the roughness value of the formed plunger hole 14. By semi-finish machining with a smaller machining allowance, the shape tolerance accuracy of the overall hole system of the rotor plunger hole can be improved, the cylindricity of the rotor plunger hole can be improved, and the dimensional accuracy of the plunger hole can be ensured.

[0024] In some embodiments, the effective length of the cutting edge of the third milling cutter 40 is greater than the machining depth of the second machining hole 13. When the third milling cutter 40 performs finish machining, tool diameter compensation can be performed for the machining allowance of the third milling cutter 40, thereby reducing the influence of tool wear on the dimensional accuracy of the formed plunger hole 14, and controlling the accuracy of each machining batch within 0.001 mm.

[0025] In some embodiments, when using a new tool or a re-sharpened tool for the second time, due to the presence of high and low points on the new tool itself and uneven surface coating, the tool wears extremely fast and it is difficult to find a pattern to control the machining allowance. Therefore, when replacing the new tool for milling, the milling speed of the tool can be increased and tool diameter compensation can be performed. The processes of semi-finish machining and finish machining can be carried out twice, with a tool compensation of -0.005 mm each time, wearing the high points of the coating of the new tool, and quickly bringing the new tool to a steady state.

[0026] In some embodiments, after the finishing process to obtain the formed plunger hole 14, it is necessary to measure the size of the formed plunger hole 14. In some embodiments, an electronic digital display pneumatic gauge can be used for measurement. The measurement is carried out in an environment with a constant temperature of 20 degrees and constant humidity, and the average value of the actually measured size is recorded. The tool compensation for tool wear is adjusted according to the feedback. Compared with the traditional internal micrometer measurement, the contact measurement is changed to an interference fit measurement method, which can prevent scratches on the machined surface of the formed plunger hole 14.

[0027] In some embodiments, the milling allowance in the radial direction of the second machining hole 13 for finishing is 2 to 3 times that of the milling allowance in the radial direction of the first machining hole 12 for semi-finishing. Thus, the surface roughness of the inner wall of the formed plunger hole 14 formed after finishing can meet the requirements of subsequent diffusion welding.

[0028] In some embodiments, the feed depth of rough machining in the axial direction of the reference plunger hole 11 is the upper limit of the hole depth tolerance during the machining of the reference plunger hole 11; the feed depth of semi-finishing in the axial direction of the first machining hole 12 is the upper limit of the hole depth tolerance during the machining of the first machining hole 12; the feed depth of finishing in the axial direction of the second machining hole 13 is the lower limit of the hole depth tolerance during the machining of the second machining hole 13. By controlling the milling depth of the tool during rough machining, semi-finishing, and finishing respectively, it is avoided that the third milling cutter 40 contacts the bottom of the second machining hole 13 during finishing, resulting in excessive milling vibration of the third milling cutter 40. Thus, the cylindricity of the formed plunger hole 14 is further improved, and the consistency of the hole system machining of the rotor plunger hole can meet the machining requirements as much as possible.

[0029] In some embodiments, in step S20, the milling path of the first milling cutter 20 in rough machining is a spiral path.

[0030] In step S30, the milling path of the second milling cutter 30 in semi-finishing is a spiral path.

[0031] In step S40, the finishing process includes: first, moving the third milling cutter 40 along the axial direction of the second machining hole 13 to a preset depth, and then controlling the third milling cutter 40 to mill the second machining hole 13 along an arc path.

[0032] By the above method, spiral milling is used in both rough machining and semi-finishing, which can make the first milling cutter 20 and the second milling cutter 30 gradually cut into the material along the spiral path, disperse the milling force, reduce the instantaneous impact, extend the tool life, and the continuous and uniform milling can reduce vibration and make the machined surface smoother. And arc milling is used in finishing, which can make the third milling cutter 40 mill continuously and smoothly according to the motion trajectory of circular arc interpolation. The movement of the machine tool is more stable, the form and position error can be reduced, and the cylindricity accuracy of the formed plunger hole 14 can be improved.

[0033] In some embodiments, step S40 includes: Step S41, based on the completion of semi-finishing, chamfering is sequentially performed on the open ends of each second machining hole 13 by a fourth milling cutter. The milling path of the fourth milling cutter is an arc, that is, the fourth milling cutter performs chamfering milling according to the movement trajectory of circular interpolation.

[0034] Step S42, based on the completion of chamfering, each second machining hole 13 is sequentially finish-machined by a third milling cutter 40 to form a formed plunger hole 14. The third milling cutter 40 is a tapered milling cutter. When the third milling cutter 40 is in a state of waiting for feed outside the second machining hole 13, the diameter of the end of the third milling cutter 40 facing the rotor semi-finished product is smaller than the diameter of the end of the third milling cutter 40 away from the rotor semi-finished product. The milling allowance in the radial direction of the second machining hole 13 during finish machining is greater than the milling allowance in the radial direction of the first machining hole 12 during semi-finishing. The milling allowance in the radial direction of the second machining hole 13 during finish machining is smaller than the milling allowance in the radial direction of the reference plunger hole 11 during rough machining. When the finish machining is completed, the formed plunger hole 14 is machined.

[0035] By the above method, as Figure 4 shown, the process of chamfering is placed between semi-finishing and finish machining, so that the burrs or steps generated near the open end of the second machining hole 13 during chamfering can be milled and covered by the subsequent finish machining third milling cutter 40, ensuring a smooth transition between the chamfer and the second machining hole 13, and improving the chamfer burr removal efficiency and the consistency of the machining of the plunger hole system.

[0036] In some embodiments, the chamfer radius of the second machining hole 13 is greater than 2% - 5% of the radius of the formed plunger hole 14. The existing chamfering is generally placed after finish machining, and the chamfer radius is generally 101% of the radius of the formed plunger hole 14, and a large chamfer is not required. In the present invention, the process of chamfering is placed between semi-finishing and finish machining. Since the diameter of the second machining hole 13 is smaller than the diameter of the formed plunger hole 14, if the chamfer radius is still 101% of the radius of the formed plunger hole 14, the remaining chamfer after being covered by finish machining will be less, which will affect the guiding effect of the chamfer during the press-fitting of the copper bushing to a certain extent. Therefore, the present invention reserves more machining allowance during chamfering, for example, it can be 105% of the radius of the formed plunger hole 14, so as to ensure a good guiding and assembling effect of the chamfer after finish machining by increasing the design requirements of the chamfer radius.

[0037] In some embodiments, the fourth milling cutter is an R corner milling cutter, and the diameter of one end of the fourth milling cutter close to the second machining hole 13 is 2 / 3 to 3 / 4 of the diameter of the formed plunger hole 14. Using an R corner milling cutter with a ratio of 2 / 3 to 3 / 4 in this embodiment can better adapt to arc milling. The formed R corner milling cutter feeds along the axis of the plunger hole. Since the milling allowance for finish machining is relatively large, the diameter of the second machining hole 13 is relatively small, and it is relatively easy to press out a stepped indentation between the end of the formed R corner milling cutter and the inner wall of the second machining hole 13. Therefore, compared with the vertical feed method of the formed milling cutter, the arc milling method with radial feed using an R corner milling cutter with a ratio of 2 / 3 to 3 / 4 in this embodiment can make the chamfered surface smoother and improve the guiding effect during the press-fitting of the copper bushing.

[0038] In some embodiments, when the fourth milling cutter for chamfering machining performs arc milling, the fourth milling cutter feeds in layers. And in the layer milling depth of the fourth milling cutter, the milling allowance of the last layer is less than the set milling range. The set milling range can be between one-fifth and one-seventh of the milling allowance of the first layer.

[0039] In some embodiments, step S20 includes: Step S21, based on the positioning of the rotor semi-finished product at the milling station being completed, the first milling cutter 20 sequentially performs rough machining on each reference plunger hole 11 according to the first rough milling allowance and the first milling sequence to form the first machining hole 12. The first rough milling allowance is the milling allowance in the radial direction of the reference plunger hole 11.

[0040] Step S22, based on the occurrence of a first failure state when the first milling cutter 20 performs rough machining on one of the reference plunger holes 11, the first failure state is repaired and eliminated. In the first failure state, the first milling cutter 20 stops performing rough machining. The first failure state can be manual stop, software failure shutdown of the processing equipment, hardware failure shutdown of the processing equipment, etc.

[0041] Step S23, based on the completion of the repair and elimination of the first failure state, the first milling cutter 20 restarts and re-performs rough machining on the reference plunger hole 11 at the fault shutdown position with the second rough milling allowance. The second rough milling allowance is the milling allowance in the radial direction of the reference plunger hole 11. The second rough milling allowance is less than the first rough milling allowance. Since the first milling cutter 20 is in a high-load milling state during rough machining, the amount of tool deflection of the first milling cutter 20 is relatively large. The milling allowance for its secondary milling of the machined surface will be much larger than the theoretical milling amount. Therefore, when the first milling cutter 20 re-mills, it needs to feed from the fault shutdown position and control the reduction of its milling allowance to reduce the influence of the tool deflection phenomenon and ensure the consistency of the machining of the rotor plunger hole system. Herein, the tool deflection phenomenon refers to the phenomenon that during the milling process, the tool or the workpiece undergoes elastic deformation due to insufficient rigidity, excessive milling force, etc., resulting in the actual milling depth being less than the programmed set value, thereby affecting the machining accuracy.

[0042] In step S24, after the rough machining of the reference plunger holes 11 at the fault shutdown position is completed, the first milling cutter 20 is controlled to successively rough-machine the subsequent reference plunger holes 11 in the first milling sequence with the first rough milling allowance.

[0043] In some embodiments, step S30 includes: In step S31, based on the completion of the rough machining, each first machining hole 12 is semi-finished in turn by the second milling cutter 30 with the first semi-finish milling allowance in the second milling sequence to form a second machining hole 13. The first semi-finish milling allowance is the milling allowance in the radial direction of the first machining hole 12.

[0044] In step S32, when a second fault state occurs during the semi-finishing of one of the first machining holes 12 by the second milling cutter 30, the second fault state is repaired and eliminated. In the second fault state, the second milling cutter 30 stops semi-finishing. The second fault state can be manual stop, software fault shutdown of the processing equipment, hardware fault shutdown of the processing equipment, etc.

[0045] In step S33, based on the completion of the repair and elimination of the second fault state, the second milling cutter 30 restarts and semi-finishes again from the first machining hole 12 at the fault shutdown position with the second semi-finish milling allowance in the second milling sequence; since the milling allowance for semi-finishing is smaller than that for rough machining and finishing, directly restarting the milling from the fault shutdown position can improve the processing efficiency.

[0046] Alternatively, based on the completion of the repair and elimination of the second fault state, the second milling cutter 30 restarts and semi-finishes each first machining hole 12 again in the second milling sequence with the second semi-finish milling allowance. The second semi-finish milling allowance is greater than the first semi-finish milling allowance. Since the second milling cutter 30 for semi-finishing performs high-speed milling and there is still a tool deflection phenomenon, in order to ensure the dimensional consistency of the second machining hole 13 formed after semi-finishing, the second milling cutter 30 needs to restart and semi-finish again from the second hole position in the second milling sequence and increase the milling allowance to cover the aperture size before the fault shutdown. The second hole position is the first first machining hole 12 machined in the second milling sequence. Among them, the second milling sequence is opposite to the first milling sequence. When the first milling sequence is clockwise, the second milling sequence can be counterclockwise, and vice versa. Thus, the machining sequence of the second milling cutter is opposite to that of the first milling cutter and the third milling cutter. Since the tool will wear during the milling process, the actual milling allowances for the tool machining in processes such as rough machining, semi-finishing, and finishing gradually decrease. By means of the first milling sequence and the second milling sequence, the consistency of the hole system diameter can be effectively improved.

[0047] In some embodiments, step S42 includes: Step S421: Based on the completion of chamfering, the third milling cutter 40 performs finish machining on each second machining hole 13 in sequence according to the first milling sequence with a first finish milling allowance. The first finish milling allowance is the milling allowance in the radial direction of the second machining hole 13 to obtain the formed plunger hole 14.

[0048] Step S422: Based on the occurrence of a third fault state when the third milling cutter 40 performs finish machining on one of the second machining holes 13, the third fault state is repaired and eliminated. In the third fault state, the third milling cutter 40 stops performing finish machining. The third fault state can be a manual stop, a software fault shutdown of the processing equipment, a hardware fault shutdown of the processing equipment, etc.

[0049] Step S423: Based on the completion of the repair and elimination of the third fault state, the third milling cutter 40 restarts and performs finish machining on each second machining hole 13 again in sequence according to the first milling sequence with a second finish milling allowance. The second finish milling allowance is greater than the first finish milling allowance. To ensure the dimensional consistency of the formed plunger hole 14 after finish machining, after the third milling cutter 40 restarts, it needs to perform finish machining again from the first hole position in sequence according to the first milling sequence and increase the milling allowance to cover the hole diameter size before the fault shutdown. The first hole position is the first hole machined by milling in the first milling sequence.

[0050] 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 method for machining a rotor plunger hole, characterized in that: The machining method of the rotor plunger hole comprises: Step S10, based on the completion of manufacturing the rotor semi-finished product, positioning the rotor semi-finished product at a milling station; the rotor semi-finished product includes a rotor body; the rotor body has a plurality of reference plunger holes; the depth of the reference plunger holes is less than the axial thickness of the rotor body; the plurality of reference plunger holes are evenly distributed around the axis of the rotor body; the diameter of the reference plunger hole is less than the diameter of the forming plunger hole; Step S20, based on the completion of positioning of the rotor semi-finished product at the milling station, rough-processing each of the reference plunger holes in sequence by a first milling cutter to form a first processed hole; the first milling cutter is a tapered milling cutter; when the first milling cutter is located outside the reference plunger hole and waiting for cutting, the diameter of the end of the first milling cutter facing the rotor semi-finished product is larger than the diameter of the end of the first milling cutter away from the rotor semi-finished product; the diameter of the first processed hole is larger than the diameter of the reference plunger hole and smaller than the diameter of the formed plunger hole; Step S30, based on the completion of the rough machining, semi-finishing each of the first machining holes in sequence by a second milling cutter to form a second machining hole; the second milling cutter is a cylindrical milling cutter; the milling allowance of the rough machining in the radial direction of the reference plunger hole is greater than the milling allowance of the semi-finishing in the radial direction of the first machining hole; the diameter of the second machining hole is greater than the diameter of the first machining hole and smaller than the diameter of the forming plunger hole; Step S40, based on the completion of the semi-finishing, each of the second processing holes is sequentially finished by a third milling cutter to form the molded plunger hole; the third milling cutter is a tapered milling cutter; the third milling cutter is located outside the second processing hole and is waiting for feed, and the diameter of the end of the third milling cutter facing the rotor semi-finished product is smaller than the diameter of the end of the third milling cutter away from the rotor semi-finished product; the milling allowance of the finishing in the radial direction of the second processing hole is greater than the milling allowance of the semi-finishing in the radial direction of the first processing hole; the milling allowance of the finishing in the radial direction of the second processing hole is less than the milling allowance of the rough machining in the radial direction of the reference plunger hole; when the finishing is completed, the molded plunger hole is processed.

2. A rotor plunger hole machining method according to claim 1, characterized in that: The milling allowance of the finish machining in the radial direction of the second machining hole is 2 to 3 times the milling allowance of the semi-finish machining in the radial direction of the first machining hole.

3. The method for machining a rotor plunger hole according to claim 1, characterized in that: The feed depth of the rough machining in the axial direction of the reference plunger hole is the upper limit of the hole depth tolerance when machining the reference plunger hole; the feed depth of the semi-finishing machining in the axial direction of the first machining hole is the upper limit of the hole depth tolerance when machining the first machining hole; The feed depth of the finish machining in the axial direction of the second machining hole is the lower limit of the hole depth tolerance during machining of the second machining hole.

4. A rotor plunger hole machining method according to claim 1, characterized in that: In the step S20, the milling path of the first milling cutter in the rough machining is a spiral path; In the step S30, the milling path of the second milling cutter in the semi-finishing is a spiral path; In the step S40, the finishing process includes: firstly, moving the third milling cutter along the axis direction of the second processing hole to a preset depth, and then controlling the third milling cutter to mill the second processing hole along an arc path.

5. The method for machining a rotor plunger hole according to claim 1, characterized in that: The step S40 comprises: Step S41, based on the completion of the semi-finishing, chamfering the opening end of each of the second processing holes in sequence by a fourth milling cutter; the milling path of the fourth milling cutter is an arc; Step S42, based on the completion of the chamfering process, each of the second processing holes is sequentially fine-processed by a third milling cutter to form the molded plunger hole; the third milling cutter is a tapered milling cutter; the third milling cutter is located outside the second processing hole and is waiting for feed, and the end diameter of the third milling cutter facing the rotor semi-finished product is smaller than the end diameter of the third milling cutter away from the rotor semi-finished product; the milling allowance of the fine processing in the radial direction of the second processing hole is greater than the milling allowance of the semi-finishing processing in the radial direction of the first processing hole; the milling allowance of the fine processing in the radial direction of the second processing hole is less than the milling allowance of the rough processing in the radial direction of the reference plunger hole; when the fine processing is completed, the molded plunger hole processing is completed.

6. A method for machining a rotor plunger hole according to claim 5, characterized in that: The chamfer radius of the second processed hole is 2% to 5% greater than the radius of the molded plunger hole.

7. A rotor plunger hole machining method according to claim 5, characterized in that: The fourth milling cutter is an R-angle milling cutter; the fourth milling cutter is close to one end of the second processing hole, and its diameter is 2 / 3 to 3 / 4 of the diameter of the forming plunger hole.

8. The method for machining a rotor plunger hole according to claim 5, characterized in that: The step S20 comprises: Step S21, based on the rotor semi-finished product being positioned at the milling station, rough-machining each of the reference plunger holes in sequence according to a first milling sequence with a first rough milling allowance to form a first machined hole by using a first milling cutter; the first rough milling allowance is a milling allowance in a radial direction of the reference plunger hole; Step S22, based on the occurrence of a first fault state when the first milling cutter performs the rough machining on one of the reference plunger holes, the first fault state is repaired and eliminated; in the first fault state, the first milling cutter stops performing the rough machining; Step S23, based on the completion of the inspection and elimination of the first fault state, the first milling cutter is restarted, and the rough machining is re-performed from the reference plunger hole at the fault stop position with a second rough milling allowance; the second rough milling allowance is the milling allowance in the radial direction of the reference plunger hole; the second rough milling allowance is less than the first rough milling allowance; Step S24 , based on the completion of the rough machining of the reference plunger hole at the fault stop position, control the first milling cutter to sequentially perform the rough machining on the subsequent reference plunger holes with the first rough milling allowance and in the first milling sequence.

9. A rotor plunger hole machining method according to claim 8, characterized in that: The step S30 comprises: Step S31, based on the completion of the rough machining, semi-finishing each of the first machining holes is sequentially performed with a second milling cutter according to a second milling sequence with a first semi-finishing milling allowance to form a second machining hole; the first semi-finishing milling allowance is a milling allowance in a radial direction of the first machining hole; Step S32, based on the occurrence of a second fault state when the second milling cutter performs the semi-finishing machining on one of the first machining holes, the second fault state is repaired and eliminated; in the second fault state, the second milling cutter stops performing the semi-finishing machining; Step S33, based on the completion of the inspection and elimination of the second fault state, the second milling cutter is restarted, and the semi-finishing machining is performed again according to the second milling sequence starting from the first machining hole at the fault stop position with a second semi-finishing milling allowance; Alternatively, based on the completion of the inspection and elimination of the second fault state, the second milling cutter is restarted, and the semi-finishing machining is re-performed on each of the first machining holes with a second semi-finishing milling allowance in accordance with the second milling sequence; the second semi-finishing milling allowance is greater than the first semi-finishing milling allowance; wherein the second milling sequence is opposite to the first milling sequence.

10. A method for machining a rotor plunger hole according to claim 9, characterized in that: The step S42 comprises: Step S421, based on the completion of the chamfering process, sequentially finish-processing each of the second processing holes with a first finishing allowance according to the first milling sequence by a third milling cutter to obtain the molded plunger hole; the first finishing allowance is the milling allowance in the radial direction of the second processing hole; Step S422, based on the occurrence of a third fault state when the third milling cutter performs the fine machining on one of the second machining holes, the third fault state is repaired and eliminated; in the third fault state, the third milling cutter stops performing the fine machining; Step S423, based on the completion of the inspection and elimination of the third fault state, the third milling cutter is restarted, and the finishing process is performed again on each of the second processing holes with a second finishing allowance in accordance with the first milling sequence; the second finishing allowance is greater than the first finishing allowance.

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