Machining method for inner curved surface of stator of hydraulic motor

Abstract

The invention provides a machining method for an inner curved surface of a stator of a hydraulic motor, and belongs to the technical field of machining. The machining method comprises the steps that a stator blank piece is provided, machining allowance is reserved on the inner curved surface of the stator blank piece, two positioning holes are formed in the stator blank piece, and the two positioning holes are located in the straight line where the same diameter of the stator blank piece is located; the positioning blank piece is assembled on a numerical control grinding machine; and the position of the stator blank on the numerical control grinding machine is corrected, so that the two positioning holes are symmetrically distributed with the center of a workbench of the numerical control grinding machine as the center. The machining precision of the inner curved surface can be improved.

Description

Technical Field

[0001] The present disclosure belongs to the field of mechanical processing technology, and in particular relates to a method for processing an inner curved surface of a stator of a hydraulic motor. Background Art

[0002] For vane-type hydraulic motors, the inner surface of the stator extends along a specific curve. The accuracy of this inner surface directly impacts the motor's service life, performance, and noise levels during operation. During machining, the inner surface must not only maintain the accuracy of the curve profile but also the position of the locating pin holes that mate with other components.

[0003] In the related art, the inner curved surface of the stator is usually processed according to the following process. First, the stator blank is rough-machined, and the inner curved surface of the stator blank is left with a finishing allowance. In addition, the rough-machined stator blank has two positioning holes spaced apart along the circumference of the stator blank. The two positioning holes are theoretically distributed in a centrally symmetrical manner about the center of the inner curved surface. Then, the rough-machined inner curved surface is fine-ground by the grinding wheel in the CNC grinder. Before fine-ground, the stator blank needs to be positioned on the workbench of the grinder. During positioning, a correction device is inserted into the positioning hole for interference fit, and the correction device includes two positioning pins that are respectively interference-fitted with the two positioning holes. By adjusting the stator blank, a micrometer is used to detect whether the two positioning pins are symmetrical about the center of the workbench. During detection, the micrometer is sucked onto the spindle of the CNC grinder, and the detection probe of the micrometer is brought into contact with the side wall of one of the positioning pins to read the detection value. The stator blank is then rotated 180° by the worktable, and the dial indicator is brought into contact with the sidewall of the other locating pin to read the test value. If the difference between the two test values ​​is within the allowable range, it is considered that the symmetric centers of the two locating holes, the center of the inner curved surface of the stator blank, and the center of the worktable coincide, indicating that the positioning of the stator blank is complete. The inner curved surface can then be fine-ground using the grinding wheel in the grinder.

[0004] However, the above method determines whether the stator blank is calibrated by measuring the outer wall runout of the locating pin. The locating pin has an interference fit with the locating hole, and the machining of the locating pin itself has certain errors. This can lead to inaccurate micrometer readings, affecting the calibration results and, in turn, the machining accuracy of the inner curved surface. Furthermore, the locating pin has an interference fit in the locating hole, making it difficult to remove after testing, which is time-consuming and labor-intensive. Summary of the Invention

[0005] The present disclosure provides a method for machining the inner curved surface of a stator of a hydraulic motor, which can improve the machining accuracy of the inner curved surface. The technical solution is as follows:

[0006] An embodiment of the present disclosure provides a method for machining the inner curved surface of a stator of a hydraulic motor, the method comprising: providing a stator blank, the inner curved surface of the stator blank having a finishing allowance, the stator blank having two positioning holes, the two positioning holes being located on a straight line having the same diameter of the stator blank; assembling the positioning blank on a CNC grinding machine; and correcting the position of the stator blank on the CNC grinding machine so that the two positioning holes are symmetrically distributed with the center of the worktable of the CNC grinding machine as the center.

[0007] In another implementation of the present disclosure, correcting the position of the stator blank on the CNC grinding machine so that the two locating holes are symmetrically distributed around the center of the worktable of the CNC grinding machine includes: detecting the inner diameter of each of the two locating holes and obtaining a radius difference between the two locating holes; obtaining, based on the radius difference, an X-direction deviation value and a Y-direction deviation value of the two locating holes in the X and Y directions of the CNC grinding machine, respectively, where the X-direction deviation refers to the difference in distance between the centers of the two locating holes and the center of the worktable in the X-axis direction, and the Y-direction deviation refers to the difference in distance between the centers of the two locating holes and the center of the worktable in the Y-axis direction; and moving the stator blank until both the X-direction deviation value and the Y-direction deviation value are no greater than a deviation threshold.

[0008] In another implementation of the present disclosure, obtaining the X-direction deviation value and the Y-direction deviation value of the two positioning holes in the CNC grinding machine respectively in the X direction and the Y direction according to the radius difference includes:

[0009] The runout values ​​of the hole walls of the two positioning holes are respectively detected by a lever micrometer; if the radius difference ΔR is not greater than the radius difference threshold, the X-direction deviation value and the Y-direction deviation value respectively satisfy the following formulas:

[0010] △L x =|L 10 -L 20 |;

[0011] △L y =|L 30 -L 40 |;

[0012] If the radius difference ΔR is greater than the radius difference threshold, the X-direction deviation value and the Y-direction deviation value respectively satisfy the following formulas:

[0013] △L x =||L 10 -L 20 |-△R|;

[0014] △L y =||L 30 -L40 |-△R|;

[0015] △R is the radius difference; L 10 、L 20 L is the detection value when the lever micrometer detects the runout value of the two inner holes in the X-axis direction; 30 、L 40 It is the detection value when the lever micrometer detects the runout value of the two inner holes in the Y-axis direction.

[0016] In another embodiment of the present disclosure, the moving of the stator blank includes: arranging a plurality of clamping assemblies at intervals along the circumference of the stator blank, each of the clamping assemblies including a clamping rod, one end of the clamping rod being movably connected to the base, the other end of the clamping rod being in contact with the outer cylindrical surface of the stator blank, the length direction of each clamping rod being the radial direction of the stator blank, and each clamping rod being movable along its own length direction; and moving the clamping rod to push the stator blank to move along the X-axis direction or the Y-axis direction of the CNC grinding machine.

[0017] In another implementation of the present disclosure, assembling the positioning blank on a CNC grinding machine includes: assembling a base on a workbench of the CNC grinding machine; placing one end of the stator blank in the base so that one end surface of the stator blank is in contact with the base, and the other end of the stator blank serves as a reference surface and faces upward.

[0018] In yet another implementation of the present disclosure, before correcting the position of the stator blank on the CNC grinding machine, the machining method further includes: detecting a plane runout value of the reference plane.

[0019] In another embodiment of the present disclosure, the processing method further includes:

[0020] The inner curved surface of the stator blank is preliminarily ground; the shortest distances between the two positioning holes and the inner curved surface after grinding are respectively detected, and a shortest distance difference is obtained; and according to the shortest distance difference, it is determined whether the position of the stator blank should be recalibrated.

[0021] In another implementation of the present disclosure, determining whether to recalibrate the position of the stator blank based on the shortest distance difference includes: if the shortest distance difference is greater than the distance threshold, recalibrating the position of the stator blank until the shortest distance difference is no greater than the distance threshold.

[0022] In yet another implementation of the present disclosure, the preliminary grinding of the inner curved surface of the stator blank includes: grinding the inner curved surface until an outermost oxide film on the inner curved surface is removed.

[0023] In yet another implementation of the present disclosure, the processing method further includes: if the shortest distance difference is not greater than the distance threshold, grinding the inner curved surface of the corrected stator blank by the CNC grinding machine.

[0024] The technical solutions provided by the embodiments of the present disclosure have the following beneficial effects:

[0025] When the inner curved surface of the stator blank is processed by the processing method provided by the embodiment of the present disclosure, since the processing method is to first clamp the stator blank on the CNC grinder and calibrate the stator blank, and when calibrating the stator blank, the center of symmetry of the two positioning holes is made the center of the worktable of the CNC grinder, the two positioning holes can be directly used as reference objects to determine whether the center of symmetry of the positioning holes (that is, the center of the inner curved surface) coincides with the center of the worktable of the CNC grinder, avoiding unnecessary errors caused by using positioning pins as reference objects, thereby improving positioning accuracy and processing accuracy. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] In order to more clearly illustrate the technical solutions in the embodiments of the present disclosure, the following briefly introduces the drawings required for use in the description of the embodiments. Obviously, the drawings described below are only some embodiments of the present disclosure. For ordinary technicians in this field, other drawings can be obtained based on these drawings without any creative work.

[0027] Figure 1 This is a flow chart of a method for processing an inner curved surface provided by an embodiment of the present disclosure;

[0028] Figure 2 is a flow chart of another method for processing an inner curved surface provided by an embodiment of the present disclosure;

[0029] Figure 3 It is a structural diagram of the stator blank;

[0030] Figure 4 It is a structural diagram of the stator blank assembly;

[0031] Figure 5 It is a schematic diagram of the X-direction deviation value and the Y-direction deviation value in the stator blank;

[0032] Figure 6 This is a schematic diagram of detecting the X-direction deviation value in the stator blank;

[0033] Figure 7 This is a schematic diagram of the inspection of h1, h2, etc. in the stator blank.

[0034] The symbols in the figure mean the following:

[0035] 100, stator blank; 101, connection hole; 102, positioning hole; 103, inner curved surface; 104, lifting hole;

[0036] 200, base; 201, mounting plane; 202, bottom plate; 203, connecting plate;

[0037] 300. Clamping assembly; 301. Clamping rod. DETAILED DESCRIPTION

[0038] In order to make the objectives, technical solutions and advantages of the present disclosure more clear, the embodiments of the present disclosure will be further described in detail below with reference to the accompanying drawings.

[0039] The inner curved surface of the hydraulic motor stator needs to be positioned and mounted on a CNC grinding machine before fine grinding. During fine grinding, the stator blank must rotate synchronously with the worktable to allow the grinding wheel to grind the inner curved surface circumferentially. Therefore, during positioning, the center of the stator blank's inner curved surface must be concentric with the center of the worktable.

[0040] The center of the inner curved surface of the stator blank cannot be determined, so the symmetry center of the two positioning holes is used as the center of the inner curved surface. Then, during correction, the position of the stator blank is judged by checking whether the symmetry center of the positioning holes coincides with the center of the workbench.

[0041] The embodiment of the present disclosure provides a method for machining the inner curved surface of a stator of a hydraulic motor, such as Figure 1 As shown, the processing method includes:

[0042] S101: Provide a stator blank.

[0043] The inner curved surface of the stator blank has a machining allowance. The stator blank has two locating holes, located on a straight line with the same diameter of the stator blank. The theoretical symmetry center of the two locating holes is the center of the inner curved surface.

[0044] Due to the limitation of machining accuracy, in actual situations, the symmetry centers of the two positioning holes may not be concentric with the center of the inner surface.

[0045] S102: Assemble the stator blank on a CNC grinding machine.

[0046] S103: Correcting the position of the stator blank so that the two positioning holes are symmetrically distributed around the center of the worktable of the CNC grinder.

[0047] The workbench center mentioned above refers to the geometric center of the workbench, which is also the rotation center of the workbench. The workbench rotates around the workbench center.

[0048] When the inner curved surface of a stator blank is processed by the processing method provided by the embodiment of the present disclosure, since the processing method is to first clamp the stator blank on a CNC grinder and calibrate the stator blank, and when calibrating the stator blank, the center of symmetry of the two positioning holes is made to be the center of the worktable of the CNC grinder, the two positioning holes can be directly used as reference objects to determine whether the center of symmetry of the positioning holes (that is, the center of the inner curved surface) coincides with the center of the worktable of the CNC grinder, thereby avoiding unnecessary errors caused by using positioning pins as reference objects, thereby improving positioning accuracy and processing accuracy. Moreover, the steps of inserting and removing positioning pins can be omitted, simplifying the calibration process and improving efficiency.

[0049] On the other hand, the embodiment of the present disclosure also provides another method for processing the inner curved surface of the stator of a hydraulic motor, such as Figure 2 As shown, the processing method includes:

[0050] S201: Provide a stator blank.

[0051] In this embodiment, the processing requirements of the stator blank are as follows: the processing is performed according to the requirements for positioning the blank in step S101 , which will not be described in detail here.

[0052] Figure 3 This is a schematic diagram of the structure of the stator blank, combined with Figure 3 In the embodiment of the present disclosure, the stator blank 100 is roughly milled or cut in a CNC lathe.

[0053] like Figure 3 As shown, the stator blank 100 is an annular structure, and the interior of the stator blank 100 has an inner curved surface 103. The inner curved surface 103 has a finishing allowance of 0.2-0.3 mm.

[0054] The stator blank 100 further has a plurality of connection holes 101 . The plurality of connection holes 101 are distributed at intervals along the circumference of the inner curved surface 103 on the outer circumference of the stator blank 100 .

[0055] Each connection hole 101 passes through both end surfaces of the stator blank 100. The connection holes 101 are used to assemble locking bolts so as to assemble the stator blank 100 in the housing of the hydraulic motor through the locking bolts.

[0056] In the embodiment of the present disclosure, the stator blank 100 can be positioned on the workbench of the CNC grinding machine by inserting a locking bolt into the connecting hole 101 .

[0057] The stator blank 100 is further provided with two positioning holes 102 . The two positioning holes 102 and the plurality of connecting holes 101 are distributed at intervals along the circumference of the inner curved surface 103 on the outer circumference of the stator blank 100 , and the two positioning holes 102 are located on the same diameter of the stator blank.

[0058] The positioning holes 102 are used to calibrate the position of the stator blank 100 on the CNC grinding machine.

[0059] In addition, to facilitate hoisting of the stator blank 100, a hoisting hole 104 is provided on the stator blank 100. The hoisting hole 104 is located on the side wall of the stator blank 100, with the axial direction of the hoisting hole 104 being radially oriented to the stator blank 100. The hoisting hole 104 is located between the two positioning holes 102. The axis of the hoisting hole 104 is perpendicular to the axis of the positioning holes 102.

[0060] In the embodiment of the present disclosure, in order to facilitate the hoisting of the stator blank 100 , the axis of the hoisting hole 104 is perpendicular to the diameter of the two positioning holes 102 .

[0061] S202: Assemble the stator blank on a CNC grinding machine.

[0062] Optionally, step S202 includes:

[0063] 2021: Assemble the base on the workbench of the CNC grinder.

[0064] 2022: Place one end of the stator blank in the base so that one end surface of the stator blank fits the base, and the other end of the stator blank serves as the reference surface and faces upward.

[0065] Figure 4 This is a schematic diagram of the stator blank assembly structure, combined with Figure 4 In the embodiment of the present disclosure, the stator blank 100 is connected to the workbench of the CNC grinding machine through the base 200 during assembly.

[0066] During assembly, the bottom surface of the base 200 is horizontal and rests on the workbench of the CNC grinding machine. The top surface of the base 200 serves as a horizontal mounting surface 201. The mounting surface 201 aligns with one end of the stator blank 100. The other end of the stator blank 100 serves as the reference surface and faces upward.

[0067] 2023: Detect the plane runout value of the reference surface.

[0068] During the inspection, the plane runout value of the reference surface of the stator blank 100 can be checked by using a lever micrometer.

[0069] When the plane runout value of the reference surface is greater than the set value (for example, 0.01 mm), it means that the plane runout value of the reference surface does not meet the requirements, indicating that the processing of the stator blank 100 does not meet the requirements and is directly scrapped.

[0070] S203: When the reference surface of the stator blank meets the requirements, the position of the stator blank on the CNC grinder is corrected so that the two positioning holes are symmetrically distributed with the center of the worktable of the grinding wheel of the CNC grinder as the center.

[0071] Optionally, step S203 includes:

[0072] 2031: Detect the inner diameters of the two positioning holes and obtain the radius difference between the two positioning holes.

[0073] In this embodiment, since the roughness and flatness of the roughly machined stator blank are different from the actual requirements, the inner diameters of the machined positioning holes 102 may vary to a certain extent.

[0074] During the inspection, the inner diameters of the two positioning holes 102 of the stator blank can be inspected by using an inner diameter micrometer.

[0075] The radius difference between the two positioning holes 102 can be obtained according to the detection result.

[0076] For example, during detection, the inner diameter of one positioning hole is D1, and the inner diameter of the other positioning hole is D2. The radius difference between the two positioning holes is △R=|D1-D2| / 2.

[0077] 2032: Based on the radius difference, obtain the X-direction deviation value and the Y-direction deviation value of the two positioning holes respectively.

[0078] Among them, the X-direction deviation value is the difference between the center of the two positioning holes and the center of the worktable in the X-axis direction of the CNC grinder, and the Y-direction deviation value is the difference between the center of the two positioning holes and the center of the worktable in the Y-axis direction of the CNC grinder.

[0079] The X-axis direction of the CNC grinder is the direction of the X-axis of the CNC grinder, which is used to control the left and right movement of the grinding wheel or worktable in the CNC grinder in the horizontal plane. The Y-axis direction of the CNC grinder is the direction of the Y-axis of the CNC grinder, which is used to control the front and back movement of the grinding wheel or worktable in the horizontal plane.

[0080] Figure 5 This is a schematic diagram of the X-axis deviation and Y-axis deviation values ​​in the stator blank, combined with Figure 5 In this embodiment, the X-axis deviation value △L x Refers to the center of the two positioning holes and the center of the workbench ( Figure 5 The difference in the distance between the position of point O in the X-axis direction. Y-axis deviation value △L y It refers to the difference in distance between the center of the two positioning holes and the center of the workbench in the Y-axis direction.

[0081] △Lx =|L x1 -L x2 |;△L y =|L y1 -L y2 |.

[0082] L x1 and L x2 L is the distance between the center of the two positioning holes and the center of the workbench in the X-axis direction; y1 and L y2 They are the distances between the centers of the two positioning holes and the center of the workbench in the Y-axis direction.

[0083] In the disclosed embodiment, the difference between the two positioning holes can be determined based on the radius difference and the radius threshold. When the radius difference is not greater than the radius threshold (for example, the radius threshold is 0.05mm), the difference between the two positioning holes is small and within the theoretical range. When the radius difference is greater than the radius threshold, the difference between the two positioning holes is large, and the deviation caused by the radius difference needs to be considered when determining the deviation between the two positioning holes in the X-axis and Y-axis directions.

[0084] In order to facilitate the detection, during the actual detection, the distance between the hole wall of the two positioning holes and the center of the workbench can be measured by the lever micrometer to obtain △L. x and △L y .

[0085] Combine Figure 5 Without considering the difference in the size of the positioning holes, assuming that the inner diameter of the positioning holes is the same, then △L x =|L1-L2|. Therefore, △L x and △L y The maximum or minimum distance between the two positioning hole walls and the center of the workbench can be determined by using a lever micrometer to detect the difference. Figure 5 L1 and L2 are shown as the minimum distances between the hole walls of the two positioning holes and the center of the workbench.

[0086] Figure 6 This is a schematic diagram of the detection of the X-direction deviation value in the stator blank, combined with Figure 6 According to the above method, the lever micrometer can detect the difference in the distance between the two positioning hole walls and the center of the workbench in the following way:

[0087] First, adjust the center line of the two positioning holes to the X-axis direction of the CNC grinder. Then, adsorb the dial base of the lever micrometer on the spindle (the spindle is coaxial with the center of the workbench), and make the detection probe of the lever micrometer be located in the positioning hole 102 on the left and on the X-axis. Adjust the pressure of the lever micrometer. When the detection probe contacts the hole wall on the side of the positioning hole closest to the center of the workbench, read the detection data L of the lever micrometer. 10 .

[0088] Because the distance between the inner wall of the positioning hole and the center of the workbench is the smallest radial deviation among all the measurement points, that is, the reading of the lever dial indicator is the smallest. Therefore, in order to simplify the measurement steps, the detection probe is directly set in the positioning hole 102 on the left side and contacts the hole wall on the side of the positioning hole 102 closest to the center of the workbench, and the detection data L can be obtained. 10 The detection data L 10 It can reflect the minimum distance L between the inner wall of the positioning hole 102 detected by the detection probe and the center of the workbench 10 The two satisfy the following relationship: L1=L 理论 +L 10 . Where L 10 L is a vector with a direction. 10 If it is greater than 0, it indicates a positive offset along the positive direction of the X axis. 10 Less than 0, indicating a reverse offset along the negative direction of the X axis. 理论 The theoretical minimum distance from the positioning hole to the center of the inner surface.

[0089] Then control the spindle to move upward, so that the lever dial indicator leaves the positioning hole, control the workbench to rotate around the center of the workbench, so that the stator blank rotates 180 degrees, and control the spindle to move downward again, so that the lever dial indicator is located at the original detection position and in another positioning hole, and read the detection data L of the lever dial indicator again. 20 The detection data L 20 It can reflect the minimum distance L2 between the inner wall of the positioning hole 102 detected by the detection probe and the center of the workbench. Similarly, L2=L 理论 +L 20 .

[0090] Without considering the difference in the size of the positioning holes, △Lx=|L1-L2|=|L 10 -L 20 |.

[0091] Similarly, in order to obtain △L y , or in the same way as above, but when testing, it is necessary to control the spindle to rotate the detection probe of the lever dial gauge 90 degrees so that it is located on the Y axis, and readjust the pressure gauge of the lever dial gauge, and then start testing to read out the detection data L30 Then, rotate the workbench 180 degrees and place the micrometer at the original detection position again, and read the detection data L of the micrometer. 40 Without considering the difference in the size of the positioning holes, △Ly=|L3-L4|=|L 30 -L 40 |.

[0092] In practice, due to the accuracy of rough machining, the inner diameters of the two positioning holes are different. In the embodiment of the present disclosure, if the radius difference △R of the two positioning holes is not greater than the third threshold value (for example, 0.05mm), the X-axis deviation value and the Y-axis deviation value respectively satisfy the following formulas:

[0093] △Lx=|L 1x -L 2x |=|L1-L2|=|L 10 -L 20 |; (1)

[0094] △Ly=|L 1y -L 2y |=|L3-L4|=|L 30 -L 40 |; (2)

[0095] If the radius difference △R is greater than the third threshold, the X-direction deviation value and the Y-direction deviation value respectively satisfy the following formulas:

[0096] △Lx=||L 1x -L 2x |-△R|=||L 10 -L 20 |-△R|; (3)

[0097] △Ly=||L 1y -L 2y |-△R|=||L 30 -L 40 |-△R|; (4)

[0098] R is the radius difference; L 10 、L 20 L is the detection value when the lever micrometer detects the runout value of the two inner holes in the X-axis direction; 30 、L 40 It is the detection value when the lever micrometer detects the runout value of the two inner holes in the Y-axis direction.

[0099] 2033: Move the stator blank until both the X-axis deviation value and the Y-axis deviation value are no greater than the deviation threshold.

[0100] Optionally, when adjusting the position of the stator blank, it can be achieved in the following manner:

[0101] (1) A plurality of clamping assemblies are arranged at intervals along the circumference of the stator blank.

[0102] Each clamping assembly includes a clamping rod, one end of which is movably connected to the base, and the other end of which contacts the outer cylindrical surface of the stator blank. The length direction of each clamping rod is the radial direction of the stator blank, and each clamping rod can move along its own length direction.

[0103] Recombination Figure 4 In the embodiment of the present disclosure, there are four clamping assemblies 300 , which are evenly spaced apart along the circumference of the stator blank 100 .

[0104] The clamping rod 301 is a screw. The clamping rod 301 is threadedly connected to the base 200, and one end of the clamping rod 301 abuts against the outer wall of the stator blank 100. When the clamping rod 301 is rotated, the stator blank 100 can be pushed to move.

[0105] In this embodiment, in order to facilitate the threaded connection of each clamping rod 301 to the base 200, the base 200 includes a cross-shaped base plate 202 and four L-shaped connecting plates 203. The four L-shaped connecting plates 203 are respectively located on the four ends of the cross-shaped base plate 202, and each connecting plate 203 is connected to the base plate 202 by fasteners.

[0106] The four connecting plates 203 correspond to the four clamping rods 301. Each clamping rod 301 is perpendicular to the corresponding connecting plate 203 and is threadedly connected.

[0107] The bottom plate 202 and the connecting plate 203 are both made of iron plates.

[0108] After the position of the stator blank is corrected, the stator blank 100 can be fastened to the base 200 by fasteners.

[0109] (2) Control the clamping rod to push the stator blank to move along the X-axis or Y-axis direction.

[0110] By rotating the clamping rod, the stator blank can be pushed to move along the X-axis direction or the Y-axis direction.

[0111] S204: Preliminary grinding of the inner curved surface of the stator blank.

[0112] To prevent oxidation or rust from occurring on the finished stator blank due to prolonged storage, the inner surface can be ground first until the outermost oxide film is removed. This means that the inner surface of the stator blank is ground initially to remove the outermost oxide film, leaving the inner surface of the stator blank completely white.

[0113] S205: Detect the shortest distances between the two positioning holes and the inner curved surface after grinding, and obtain the shortest distance difference.

[0114] The shortest distances h1 and h2 between the hole wall and the inner curved surface of the two positioning holes are detected respectively, and then the shortest distance difference △h=|h1-h2| can be obtained.

[0115] Figure 7 This is a schematic diagram of the detection of h1 and h2 in the stator blank, combined with Figure 7 When h1 and h2 are obtained, a double-round micrometer can be used to respectively detect the distance H1 and H2 between the center of each positioning hole and the inner surface, and then h1 and h2 can be obtained by subtracting the radius of the corresponding positioning hole from H1 and H2.

[0116] h1=H1-R1; (5)

[0117] h2=H2-R2; (6)

[0118] Wherein, h1 is the shortest distance between the hole wall of one of the positioning holes and the inner curved surface; H1 is the shortest distance between the center of one of the positioning holes and the inner curved surface; R1 is the radius of one of the positioning holes;

[0119] h2 is the shortest distance between the hole wall of another positioning hole and the inner curved surface; H2 is the shortest distance between the center of another positioning hole and the inner curved surface; R2 is the radius of another positioning hole.

[0120] S206: Determine whether to recalibrate the position of the stator blank based on the shortest distance difference and the distance threshold.

[0121] If the shortest distance difference Δh is not greater than the distance threshold, the position of the stator blank does not need to be recalibrated. Execute S207. If the shortest distance difference Δh is greater than the distance threshold, the position of the stator blank needs to be recalibrated. Execute S208.

[0122] The distance threshold is 0.005mm.

[0123] If △h is not greater than the distance threshold, the shortest distance between the two locating holes and the inner surface is the same, and the two locating holes are located at the same position relative to the inner surface. This further confirms that the two locating holes are symmetrical about the center of the worktable. This indicates that the stator blank is clamped correctly and can be subsequently ground.

[0124] On the contrary, when △h is greater than the distance threshold, it means that the clamping of the stator blank does not meet the requirements. The workbench is rotated to the position where the positioning blank is not assembled, and the stator blank is re-calibrated.

[0125] S207: Grinding the inner surface by a CNC grinding machine.

[0126] If the stator blank is calibrated, the CNC grinding machine's processing program can be run to grind the inner surface until the accuracy of the inner surface meets the requirements.

[0127] S208: Determine whether the number of corrections is less than a set value.

[0128] When recalibrating the position of the stator blank, it is necessary to determine whether the number of corrections is less than a set value based on the number of corrections. In some cases, if the stator blank does not meet the aforementioned requirement of Δh being less than the distance threshold after the calibration is performed according to the above steps and the number of corrections exceeds the set value (e.g., 2), this may be due to a problem with the CNC grinder itself causing the stator blank to fail to meet the calibration requirements. In this case, S209 can be executed to readjust or reset the CNC grinder's machining coordinate system.

[0129] S209: After adjusting the machining coordinate system of the CNC grinding machine, execute S202-S205.

[0130] For example, the origin of the machining coordinate system may be offset by △h / 2 in the positive direction along the axis direction, and then recalibrated according to the steps in S202 to S205.

[0131] It's important to note that after resetting the coordinate system, further verification of program compensation is required. After modifying the machining coordinate system, raise the grinding wheel above the reference plane of the stator blank to ensure there is no interference between the grinding wheel and the reference plane. Run the program with a dry cut and record whether the X coordinate value of the grinding wheel has changed from the original. If the new X coordinate value increases by △h / 2, the program correction is correct.

[0132] The above processing method can improve the processing efficiency of the stator and at the same time improve the qualified rate of the product.

[0133] The above description is merely an optional embodiment of the present disclosure and is not intended to limit the present disclosure. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present disclosure shall be included in the scope of protection of the present disclosure.

Claims

1. A method for machining the inner curved surface of a stator of a hydraulic motor, characterized in that: The processing method comprises: Providing a stator blank, wherein the inner curved surface of the stator blank has a finishing allowance, and the stator blank has two positioning holes, wherein the two positioning holes are located on a straight line having the same diameter of the stator blank; Assembling the positioning blank on a CNC grinding machine; The position of the stator blank on the CNC grinding machine is corrected so that the two positioning holes are symmetrically distributed with the center of the worktable of the CNC grinding machine as the center.

2. The processing method according to claim 1, characterized in that: The position of the stator blank is corrected on the CNC grinding machine so that the two positioning holes are symmetrically distributed with the center of the worktable of the CNC grinding machine as the center. Detecting the inner diameters of the two positioning holes and obtaining a radius difference between the two positioning holes; According to the radius difference, obtain the X-direction deviation value and Y-direction deviation value of the two positioning holes in the CNC grinding machine in the X and Y directions respectively, wherein the X-direction deviation refers to the difference in distance between the centers of the two positioning holes and the center of the worktable in the X-axis direction, and the Y-direction deviation refers to the difference in distance between the centers of the two positioning holes and the center of the worktable in the Y-axis direction; The stator blank is moved until both the X-direction deviation value and the Y-direction deviation value are no greater than a deviation threshold value.

3. The processing method according to claim 2, characterized in that: The step of obtaining the X-direction deviation value and the Y-direction deviation value of the two positioning holes in the CNC grinding machine respectively in the X-direction and the Y-direction according to the radius difference comprises: Using a lever dial gauge to detect the runout values ​​of the hole walls of the two positioning holes respectively; If the radius difference ΔR is not greater than the radius difference threshold, the X-direction deviation value and the Y-direction deviation value respectively satisfy the following formulas: △Lx=|L 10 -L 20 |; △Ly=|L 30 -L 40 |; If the radius difference ΔR is greater than the radius difference threshold, the X-direction deviation value and the Y-direction deviation value respectively satisfy the following formulas: △Lx=||L 10 -L 20 |-△R|; △Ly=||L 30 -L 40 |-△R|; △R is the radius difference; L 10 、L 20 L is the detection value when the lever micrometer detects the runout value of the two inner holes in the X-axis direction; 30 、L 40 It is the detection value when the lever micrometer detects the runout value of the two inner holes in the Y-axis direction.

4. The processing method according to claim 2, characterized in that: The moving of the stator blank comprises: A plurality of clamping assemblies are arranged at intervals along the circumference of the stator blank, each of the clamping assemblies comprising a clamping rod, one end of the clamping rod being movably connected to the base, the other end of the clamping rod being in contact with the outer circumferential surface of the stator blank, the length direction of each clamping rod being the radial direction of the stator blank, and each clamping rod being movable along its own length direction; The clamping rod is moved to push the stator blank to move along the X-axis direction or the Y-axis direction of the CNC grinding machine.

5. The processing method according to claim 1, characterized in that: The step of assembling the positioning blank on a CNC grinding machine comprises: Assembling the base on the workbench of the CNC grinding machine; One end of the stator blank is placed in the base so that one end surface of the stator blank is in contact with the base, and the other end of the stator blank serves as a reference surface and faces upward.

6. The processing method according to claim 5, characterized in that: Before correcting the position of the stator blank on the CNC grinding machine, the processing method further includes: Detecting the plane runout value of the reference surface.

7. The processing method according to claim 1, characterized in that: The processing method further comprises: performing preliminary grinding on the inner curved surface of the stator blank; respectively detecting the shortest distances between the two positioning holes and the inner curved surface after grinding, and obtaining a shortest distance difference; Whether to re-correct the position of the stator blank is determined based on the shortest distance difference.

8. The processing method according to claim 7, characterized in that: Determining whether to re-correct the position of the stator blank according to the shortest distance difference includes: If the shortest distance difference is greater than the distance threshold, the position of the stator blank is re-adjusted until the shortest distance difference is no greater than the distance threshold.

9. The processing method according to claim 7, characterized in that: The preliminary grinding of the inner curved surface of the stator blank comprises: The inner curved surface is ground until the outermost oxide film of the inner curved surface is removed.

10. The processing method according to claim 8, characterized in that: The processing method further comprises: If the shortest distance difference is not greater than the distance threshold, the inner curved surface of the corrected stator blank is ground by the CNC grinding machine.

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