A machining method for a rotor plunger hole

Abstract

The present invention relates to the technical field of plunger pump processing. Specifically, it relates to a processing method for the plunger holes of a rotor. The processing method includes steps S10 to S40. The processing method is based on the completion of manufacturing the rotor semi-finished product, and positioning the rotor semi-finished product at the milling station; rough machining each of the reference plunger holes with a first milling cutter to form a first processing hole; then semi-finishing each of the first processing holes with a second milling cutter to form a second processing hole; then finishing each of the second processing holes with a third milling cutter to form the formed plunger hole; the milling allowance in the radial direction of the second processing hole during the finishing is greater than the milling allowance in the radial direction of the first processing hole during the semi-finishing. In this way, while achieving the purpose of reducing the accuracy grade of the hole wall roughness of the rotor plunger hole, the processing accuracy is improved, thereby being able to improve the diffusion welding quality between the plunger hole wall and the copper bushing.

Description

Technical Field

[0001] The present invention relates to the technical field of plunger pump processing, and more specifically, to a processing method for the plunger holes of a rotor. 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 multiple radially or axially distributed plunger holes for accommodating the plunger rod. The plunger rod is usually cylindrical, with one end connected to the rotor and the other end sliding within the plunger hole. The rotor, plunger rod, and plunger hole work together. The rotation of the rotor drives the reciprocating movement of the plunger rod, and the plunger rod slides within 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 component, have been gradually increasing. 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 the rotor plunger hole, including:

[0005] 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 multiple reference plunger holes; the depth of the reference plunger holes is less than the axial thickness of the rotor body; the multiple 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;

[0006] 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 conical milling cutter; when the first milling cutter is in a state of waiting to 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;

[0007] Step S30, based on the completion of the rough machining, each of the first machining holes is 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 during the rough machining is greater than the milling allowance in the radial direction of the first machining hole during 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;

[0008] Step S40, based on the completion of the semi-finishing, each of the second machining holes is 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 to feed outside the second machining hole, the end diameter of the third milling cutter facing the end of 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 during the finishing is greater than the milling allowance in the radial direction of the first machining hole during the semi-finishing; the milling allowance in the radial direction of the second machining hole during the finishing is less than the milling allowance in the radial direction of the reference plunger hole during the rough machining; when the finishing is completed, the formed plunger hole machining is completed.

[0009] In some embodiments, the milling allowance in the radial direction of the second machining hole during the finishing is 2 to 3 times the milling allowance in the radial direction of the first machining hole during the semi-finishing.

[0010] 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.

[0011] In some embodiments, in step S20, the milling path of the first milling cutter in the rough machining is a spiral path;

[0012] In step S30, the milling path of the second milling cutter in the semi-finishing is a spiral path;

[0013] 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.

[0014] In some embodiments, step S40 includes:

[0015] Step S41, based on the completion of the semi-finishing, chamfer each opening end of the second processing holes in sequence by a fourth milling cutter; the milling path of the fourth milling cutter is an arc;

[0016] Step S42, based on the completion of the chamfering, finish-machine each of the second processing holes by a third milling cutter to form the formed plunger holes; 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 processing 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 of the finish-machining 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 finish-machining in the radial direction of the second processing hole is smaller than the milling allowance of the rough machining in the radial direction of the reference plunger hole; in the state where the finish-machining is completed, the machining of the formed plunger holes is completed.

[0017] In some embodiments, the chamfer radius of the second processing hole is greater than 2% - 5% of the radius of the formed plunger hole.

[0018] 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 processing hole is 2 / 3 - 3 / 4 of the diameter of the formed plunger hole.

[0019] In some embodiments, the step S20 includes:

[0020] Step S21, based on the completion of the positioning of the rotor semi-finished product at the milling station, rough-machine each of the reference plunger holes in sequence by a first milling cutter with a first rough milling allowance according to a first milling sequence to form first processing holes; the first rough milling allowance is the milling allowance in the radial direction of the reference plunger hole;

[0021] Step S22, based on the occurrence of a first failure state when the first milling cutter rough-machines one of the reference plunger holes, repair and eliminate the first failure state; in the first failure state, the first milling cutter stops the rough-machining;

[0022] Step S23, based on the completion of the repair and elimination of the first failure state, restart the first milling cutter and re-rough-machine 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;

[0023] Step S24, based on the completion of rough machining of the reference plunger holes at the fault shutdown position, control the first milling cutter to perform the rough machining on the subsequent reference plunger holes in sequence according to the first milling order with the first rough milling allowance.

[0024] In some embodiments, the step S30 includes:

[0025] Step S31, based on the completion of the rough machining, use a second milling cutter to perform semi-finishing on each of the first machining holes in sequence according to the second milling order with a first semi-finishing allowance to form second machining holes; the first semi-finishing allowance is the milling allowance upward from the diameter of the first machining hole;

[0026] Step S32, based on a second fault state occurring when the second milling cutter performs the semi-finishing on one of the first machining holes, repair and eliminate the second fault state; in the second fault state, the second milling cutter stops performing the semi-finishing;

[0027] Step S33, based on the completion of the repair and elimination of the second fault state, restart the second milling cutter, and starting from the first machining hole at the fault shutdown position, perform the semi-finishing again in accordance with the second milling order with a second semi-finishing allowance;

[0028] Or, based on the completion of the repair and elimination of the second fault state, restart the second milling cutter, and perform the semi-finishing on each of the first machining holes again in accordance with the second milling order with a second semi-finishing allowance; the second semi-finishing allowance is greater than the first semi-finishing allowance; wherein, the second milling order is opposite to the first milling order.

[0029] In some embodiments, the step S42 includes:

[0030] Step S421, based on the completion of the chamfering, use a third milling cutter to perform finish machining on each of the second machining holes in sequence according to the first milling order with a first finish milling allowance to obtain the formed plunger holes; the first finish milling allowance is the milling allowance upward from the diameter of the second machining hole;

[0031] Step S422, based on a third fault state occurring when the third milling cutter performs the finish machining on one of the second machining holes, repair and eliminate the third fault state; in the third fault state, the third milling cutter stops performing the finish machining;

[0032] Step S423, based on the completion of the repair and elimination of the third fault state, restart the third milling cutter and perform the finish machining on each of the second machining holes again in accordance with the first milling order with a second finish milling allowance; the second finish milling allowance is greater than the first finish milling allowance.

[0033] To solve the problem that the quality of the diffusion welding between the rotor plunger hole and the copper bushing needs to be further improved, the present invention has the following advantages:

[0034] The present invention adopts a method in which the machining allowance of finish machining is greater than that of 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 hole wall roughness of the rotor formed plunger hole, and further improving the quality of the diffusion welding 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 shape 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 of finish machining to be greater than that of semi-finish machining. Description of the Drawings

[0035] Figure 1 The flowchart shows a method for machining a rotor plunger hole according to an embodiment;

[0036] Figure 2 The schematic diagram shows the states before and after rough machining of the reference plunger hole in a method for machining a rotor plunger hole according to an embodiment;

[0037] 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;

[0038] Figure 4 The schematic diagram shows the state after chamfering machining in a method for machining a rotor plunger hole according to an embodiment;

[0039] 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.

[0040] 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

[0041] 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 to the scope of the present disclosure.

[0042] 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 relationships indicated by the terms "upper", "lower", "left", "right", "front", "rear", "top", "bottom", "inner", "outer", "vertical", "horizontal", "lateral", "longitudinal", etc. are based on the orientation or positional relationships 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 orientation or positional relationships, 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" shall 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.

[0043] The core components of the 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 the rotor. In some embodiments, as Figure 1 shown, the processing method for the plunger holes of the rotor includes:

[0044] 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 rotor semi-finished product 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.

[0045] Step S20, based on the positioning of the rotor semi-finished product 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 rotor semi-finished product is greater than the end diameter of the first milling cutter 20 away from the rotor semi-finished product, 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 head is large, and a more firm and stable tool head 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 machining 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.

[0046] 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.

[0047] Step S40, based on the completion of semi-finishing, finish machining 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 tapered milling cutter. When the third milling cutter 40 is located outside the second machining hole 13 and waiting for feed, 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, that is, a positive tapered 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 for the surface roughness of the inner wall of the formed plunger hole 14, that is, reducing the accuracy grade of the hole wall roughness 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.

[0048] 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 tapered 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.

[0049] 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.

[0050] In some embodiments, when using a new tool or a regrinded 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.

[0051] In some embodiments, after obtaining the formed plunger hole 14 upon completion of the finishing process, dimensional measurement of the formed plunger hole 14 is required. 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 recorded according to the average value of the actual measured dimensions. The tool compensation for tool wear is adjusted based on the feedback. Compared with the traditional internal micrometer measurement, the measurement method is changed from contact measurement to clearance fit measurement, which can prevent scratching of the machined surface of the formed plunger hole 14.

[0052] In some embodiments, the milling allowance in the radial direction of the second machining hole 13 during finishing is 2 to 3 times that of the milling allowance in the radial direction of the first machining hole 12 during 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.

[0053] 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. Thereby, the cylindricity of the formed plunger hole 14 is further improved, and the machining consistency of the hole system of the rotor plunger hole is made to meet the machining requirements as much as possible.

[0054] In some embodiments, in step S20, the milling path of the first milling cutter 20 in rough machining is a spiral path.

[0055] In step S30, the milling path of the second milling cutter 30 in semi-finishing is a spiral path.

[0056] 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.

[0057] By the above method, spiral milling is used in both rough machining and semi-finishing, which can enable the first milling cutter 20 and the second milling cutter 30 to 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. While arc milling is used in finishing, which can enable the third milling cutter 40 to 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.

[0058] In some embodiments, step S40 includes:

[0059] Step S41, based on the completion of semi-finishing, chamfering is sequentially performed on the open ends of each second processing 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 circular interpolation motion trajectory.

[0060] Step S42, based on the completion of chamfering, each second processing 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 processing hole 13, the diameter of the end of the third milling cutter 40 facing the end of 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 processing hole 13 during finish machining is greater than the milling allowance in the radial direction of the first processing hole 12 during semi-finishing. The milling allowance in the radial direction of the second processing hole 13 during finish machining is smaller than the milling allowance in the radial direction of the reference plunger hole 11 during rough machining. In the state where the finish machining is completed, the formed plunger hole 14 is machined.

[0061] By the above method, as Figure 4 shown, the process of chamfering is placed between semi-finishing and finish machining, so that the third milling cutter 40 for subsequent finish machining can be used to mill and cover the burrs or steps generated near the open end of the second processing hole 13 during chamfering, ensuring a smooth transition between the chamfer and the second processing hole 13, and improving the chamfer burr removal efficiency and the consistency of the plunger hole system machining.

[0062] In some embodiments, the chamfer radius of the second processing 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, however, the process of chamfering is placed between semi-finishing and finish machining. Since the diameter of the second processing 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 to a certain extent affect the guiding effect of the chamfer during the press-fitting of the copper bushing. Therefore, in the present invention, the machining allowance reserved during chamfering is relatively large, for example, it can be 105% of the radius of the formed plunger hole 14, so as to ensure that the chamfer after finish machining has a good guiding and assembling effect by increasing the design requirements of the chamfer radius.

[0063] 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. In this embodiment, using an R corner milling cutter with a ratio of 2 / 3 to 3 / 4 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 stepped indentations 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.

[0064] 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-by-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.

[0065] In some embodiments, step S20 includes:

[0066] Step S21, based on the positioning of the rotor semi-finished product at the milling station being completed, the first milling cutter 20 performs rough machining on each reference plunger hole 11 in sequence 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.

[0067] 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.

[0068] Step S23, based on the completion of the repair and elimination of the first failure state, the first milling cutter 20 restarts and performs rough machining again 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 tool deflection amount of the first milling cutter 20 is relatively large during the tool deflection phenomenon, and 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 performs milling again, it needs to feed from the fault shutdown position and control its milling allowance to decrease, reducing the influence of the tool deflection phenomenon and ensuring the consistency of the machining of the rotor plunger hole system. Among them, the tool deflection phenomenon refers to the phenomenon that during the milling process, the tool or the workpiece undergoes elastic deformation due to factors such as insufficient rigidity and excessive milling force, resulting in the actual milling depth being less than the programmed set value, thereby affecting the machining accuracy.

[0069] Step S24, after rough machining of the reference plunger holes 11 at the fault shutdown position is completed, control the first milling cutter 20 to successively rough machine the subsequent reference plunger holes 11 in the first milling sequence with the first rough milling allowance.

[0070] In some embodiments, step S30 includes:

[0071] Step S31, after rough machining is completed, use the second milling cutter 30 to semi-finish machine each first machining hole 12 in the second milling sequence with the first semi-finish milling allowance 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.

[0072] 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, repair and eliminate the second fault state. 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.

[0073] Step S33, after the repair and elimination of the second fault state is completed, restart the second milling cutter 30, and start from the first machining hole 12 at the fault shutdown position with the second semi-finish milling allowance, and re-perform semi-finishing 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.

[0074] Alternatively, after the repair and elimination of the second fault state is completed, restart the second milling cutter 30, and re-perform semi-finishing on each first machining hole 12 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 phenomenon of tool deflection, in order to ensure the dimensional consistency of the second machining hole 13 formed after semi-finishing, the second milling cutter 30 needs to re-perform semi-finishing from the second hole position in the second milling sequence and increase the milling allowance after restarting, so as to cover the aperture size before the fault shutdown. The second hole position is the first first machining hole 12 in the second milling sequence for milling. 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 allowance for tool machining in processes such as rough machining, semi-finishing, and finishing gradually decreases. By means of the first milling sequence and the second milling sequence, the diameter consistency of the hole system can be effectively improved.

[0075] In some embodiments, step S42 includes:

[0076] Step S421: Based on the completion of chamfering, each second processing hole 13 is sequentially finish-machined by a third milling cutter 40 with a first finish-milling allowance according to a first milling sequence to obtain a formed plunger hole 14. The first finish-milling allowance is the milling allowance in the radial direction of the second processing hole 13.

[0077] Step S422: Based on a third failure state occurring when the third milling cutter 40 performs finish machining on one of the second processing holes 13, the third failure state is repaired and eliminated. In the third failure state, the third milling cutter 40 stops performing finish machining. The third failure state can be a manual stop, a software failure shutdown of the processing equipment, a hardware failure shutdown of the processing equipment, etc.

[0078] Step S423: Based on the completion of the repair and elimination of the third failure state, the third milling cutter 40 restarts and re-performs finish machining on each second processing hole 13 with a second finish-milling allowance according to the first milling sequence. 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 re-perform finish machining from the first hole position according to the first milling sequence and increase the milling allowance to cover the hole diameter size before the failure shutdown. The first hole position is the first hole machined by milling in the first milling sequence.

[0079] 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 to them 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; when the third milling cutter is located outside the second processing hole and waiting for cutting, 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 larger 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 smaller 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; 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.

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: 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.

5. A rotor plunger hole machining method according to claim 4, characterized in that: The chamfer radius of the second processed hole is 2% to 5% greater than the radius of the molded plunger hole.

6. A rotor plunger hole machining method according to claim 4, 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.

7. A rotor plunger hole machining method according to claim 4, 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.

8. A rotor plunger hole machining method according to claim 7, 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.

9. A rotor plunger hole machining method according to claim 8, 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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