A method for milling a track of a stator of a ball piston pump based on UG

Abstract

This invention provides a UG-based method for milling the stator track of a ball piston pump. The method includes: establishing a coordinate system and constructing a mathematical model of the inner curve of the stator track on the coordinate system; generating the inner curve of the stator track based on the mathematical model, generating a stator geometric model based on the inner curve, and designing the CNC machining process and setting the parameters of the machining tools based on the stator geometric model; performing pre-rough milling on the concave side structure of the stator track according to a first preset rule, and performing pre-semi-finishing and pre-finishing on the curved surface of the stator track according to a second preset rule to generate the stator track milling tool path; using the UG toolpath to detect the contact condition, and if the detection is qualified, performing roughing, semi-finishing, and finishing of the stator track. This invention enables seamless integration of CAD / CAM for the inner curve ball piston pump stator track, broadening the methods for stator track machining.

Description

Technical Field

[0001] This invention relates to the field of ball piston pump manufacturing technology, and in particular to a ball piston pump stator track milling method based on UG. Background Technology

[0002] Ball piston pumps are a type of high-tech, novel radial hydraulic pump. They are technologically advanced, easily achieving high power and large displacement, and possess a compact structure, making them promising for applications. They are particularly widely used in continuously variable transmissions and steering systems in military vehicles, but their development has been challenging, thus remaining a long-standing research hotspot in global hydraulic technology.

[0003] Currently, research on ball plug pumps mainly focuses on product development, performance analysis, material selection, and structural design. Examples include studies on the output characteristics of radial ball plug systems based on AMESim and ADAMS, stator curves of novel low-flow pulsating radial ball plug pumps, dynamic and static pressure support principles of ball plug pump distribution shafts, and constant-pressure water supply systems using ball plug pumps. However, research on machining methods for ball plug pumps is scarce.

[0004] Due to the different sealing methods, ball piston pumps have more stringent processing requirements and greater technological difficulty compared to plunger pumps. As one of the core components of a ball piston pump, the stator track is naturally a key focus of research on its processing technology. Its high-precision, complex inner curve stator track with its concave sides presents significant challenges in CNC programming and machining, and its machining quality directly impacts the movement quality of the ball piston within the stator track. Summary of the Invention

[0005] The purpose of this invention is to provide a milling method for the stator track of a ball piston pump based on UG, which aims to overcome the machining difficulties of complex curved surfaces with lateral concave sides of the stator track, realize seamless integration of CAD / CAM for the internal curve ball piston pump stator track, and broaden the machining methods for stator tracks.

[0006] In a first aspect, the present invention provides a method for milling the stator track of a ball piston pump based on UG, the method comprising:

[0007] A coordinate system is established based on the stator track structure, and a mathematical model of the curves within the stator track is constructed on the coordinate system.

[0008] Based on the mathematical model, the inner curve of the stator track is generated in UG software, and the stator geometric model is generated based on the inner curve of the stator track. Based on the stator geometric model, the CNC machining process of the stator track is designed and the machining parameters are set.

[0009] The stator track side concave structure is pre-rough milled according to the first preset rule, and the stator track curved surface is pre-semi-finished and pre-finished according to the second preset rule. The stator track milling tool trajectory is generated based on the pre-rough milling, pre-semi-finishing and pre-finishing.

[0010] The UG toolpath is used to detect the stator track milling tool path. If the detection is qualified, the stator track roughing, semi-finishing and finishing are performed.

[0011] In some embodiments, establishing a coordinate system based on the stator track structure and constructing a mathematical model of the curve within the stator track on the coordinate system includes:

[0012] A stator track modeling coordinate system is established with the center of the stator track as the origin, the x-axis as the direction of the major semi-axis of the stator track, and the y-axis as the direction of the minor semi-axis of the stator track.

[0013] A mathematical model is constructed in the stator track modeling coordinate system according to the following formula:

[0014] ;

[0015] in, , , For the major semi-axis of the stator track, For the short semi-axis of the stator track, Let the radius of the ball plug be . For the stator track groove depth, Let k be the angle between the line connecting point k and the origin and the x-axis, where k is the point k on the curve inside the stator track.

[0016] In some embodiments, generating the stator track inner curve in UG software according to the mathematical model includes:

[0017] make , , , , , , ;

[0018] And order Substituting these parameters into the mathematical model, the ball piston pump parameters are set, and a mathematical expression for the stator track inner curve is constructed in UG software:

[0019] ;

[0020] ;

[0021] Where t is a built-in variable in the UG software, with a value range of 0 to 1; when t=0, When t=1, ; , Z kt These represent the x-axis coordinates, y-axis coordinates, z-axis coordinates, and Z-axis coordinates of point k at time t within the stator track curve.kt =0.

[0022] In some embodiments, generating a stator geometric model based on the stator track curve includes:

[0023] by Point k is the center of the circle, and a circle is generated in the normal plane of the curve within the stator track with the radius of the ball plug as the radius.

[0024] The circle is swept along the inner curve of the stator track to generate the swept body of the ball plug along the inner curve of the stator track;

[0025] The stator's rotating body is created using the rotation and sweep function of UG software, and a Boolean subtraction operation is performed between the rotating body and the swept body to obtain the stator's geometric model.

[0026] In some embodiments, the step of designing the CNC machining process for the stator track based on the stator geometric model and setting the machining parameters includes:

[0027] Using CNC turning technology, all stator surfaces except the stator track surface are turned out, and the stator track is then CNC milled using these as blanks.

[0028] The stator track is milled using a single-edged milling cutter. During the machining process, the spherical tip of the single-edged milling cutter always maintains a tangential contact mode with the curved surface of the stator track and is machined along the streamline direction of the curved surface of the stator track.

[0029] The cutting edge radius in the T-shaped tool parameter table in UG software and All are set to single-flute end mill ball cutter radius, and the cutting edge length in the T-cutter parameter table is set to twice the ball cutter radius to form a spherical cutter head.

[0030] In some embodiments, the pre-rough milling of the stator track side concave structure according to a first preset rule includes:

[0031] A first intersection plane, a second intersection plane, and a third intersection plane are generated, wherein the second intersection plane is located between the first intersection plane and the third intersection plane;

[0032] The first, second, and third intersecting planes are all parallel to the stator track plane. The second intersecting plane passes through the center of the stator track. The height range of the first and third intersecting planes does not exceed the width range of the shallowest part of the stator track side concavity.

[0033] The intersection lines between the stator track and the first, second, and third intersection planes are obtained respectively, and the calculated profiles of the first, second, and third intersection planes are obtained.

[0034] The stator geometry is machined using the calculated profile as the 2D profile of UG software.

[0035] In some embodiments, the pre-semi-finishing and pre-finishing of the stator track surface according to the second preset rule includes:

[0036] Construct a reference plane that passes through the major axis of the stator track and is perpendicular to the second intersection plane. Find the intersection line between the reference plane and the surface of the stator track, and use the UG curve extension function to extend the intersection line to obtain the extended intersection line.

[0037] The extended intersection line is swept along the path of the intersection line between the second intersection plane and the stator track to obtain a swept surface that fits the stator track and has a width range greater than the processing range of the stator track.

[0038] A surface is offset by the normal of the swept surface, and this offset surface is used as the driving geometry for the stator track fixed shaft contour milling. The machining allowance of the stator track is changed by modifying the offset distance of the offset surface in the modeling module. Then, the tool path is generated in the machining module to realize the pre-semi-finishing and pre-finishing of the stator track surface.

[0039] In some embodiments, the second preset rule further includes:

[0040] The spiral toolpath cutting mode is adopted, and the spiral cutting direction is consistent with the direction of ball plug movement on the stator track.

[0041] The driving method adopts curved area driving, and the projection vector is set to a mode away from the straight line, which is the center line of the stator track axis.

[0042] It adopts a large central angle arc entry and exit cutting mode, and sets the central angle of the entry and exit arcs to 180 degrees.

[0043] In some embodiments, the use of UG toolpath detection to determine the stator track milling tool path, and if the detection is satisfactory, then roughing, semi-finishing, and finishing of the stator track are performed; including:

[0044] Check whether the tool path matches the streamline of the stator track surface and whether it meets the requirements of the ball piston pump for the machining texture of the stator track surface.

[0045] If the tool path matches the streamline of the stator track surface and meets the requirements of the ball piston pump for the machining texture of the stator track surface, then the inspection is qualified.

[0046] Compared with the prior art, the present invention has the following advantages:

[0047] This invention proposes a method for milling the stator track of a ball piston pump. First, a UG mathematical model is established based on the formula for the inner curve of the stator track, generating the inner curve of the stator track and establishing a 3D geometric model of the inner curve stator track. Based on this, the process design is carried out according to the structural characteristics and machining requirements of the stator track, setting the cutting tool, machining geometry, and toolpath driving geometry. The toolpath is rationally planned according to the streamline of the stator track surface. The machining allowance is adjusted by changing the offset surface distance of the stator track. This method overcomes the difficulty of machining the complex, laterally concave surface of the stator track, realizing UG-based milling of the ball piston pump stator track, achieving seamless integration of CAD / CAM for the inner curve ball piston pump stator track, and broadening the methods for stator track machining. Attached Figure Description

[0048] Figure 1 A flowchart of a ball piston pump stator track milling method based on UG proposed in one embodiment of the present invention;

[0049] Figure 2 Example diagram of stator geometry model;

[0050] Figure 3 Example diagram of tool parameter settings;

[0051] Figure 4 This is a schematic diagram of rough milling layers;

[0052] Figure 5 This is a schematic diagram of an offset surface;

[0053] Figure 6 Example diagram for setting up a helical drive;

[0054] Figure 7 Example diagram for setting up fixed profile milling;

[0055] Figure 8 This is an example diagram of the tool trajectory for stator track milling.

[0056] The following detailed description, in conjunction with the accompanying drawings, will further illustrate the present invention. Detailed Implementation

[0057] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention. Unless otherwise defined, the technical or scientific terms used herein should have the ordinary meaning understood by those skilled in the art. The terms "comprising" and similar expressions used herein mean that the element or object preceding the word covers the element or object listed after the word and its equivalents, but does not exclude other elements or objects.

[0058] The applicant discovered the following problems with the technology for processing the stator track structure:

[0059] 1. The ball plug moves along the stator track under the combined constraint of the stator track and the rotor cylinder. The ball plug contacts the curved surface of the stator track, exhibiting both rolling and sliding motion. The stator track must be compatible with the ball plug pump rotor and distribution shaft. The stator track has a "bowl"-shaped structure and a side-concave track surface, requiring high machining precision and presenting significant machining challenges.

[0060] 2. The texture of the stator track surface will affect the ball piston's motion quality and the wear between the ball piston and the stator track, thus affecting the ball piston pump's performance, reliability, and service life. Therefore, the tool path must conform to the streamline of the stator track surface.

[0061] 3. The equations of the curves within the stator track are complex, making it difficult to perform geometric modeling of the stator track surface in a CAD / CAM software environment.

[0062] 4. UG software primarily generates toolpaths by controlling the tool axis vector, projection direction, and driving method. However, for the stator track surface of the "bowl"-shaped concave structure, it is difficult to set the driving geometry and the machining geometry.

[0063] Based on this, such as Figure 1 As shown, one embodiment of the present invention proposes a method for milling the stator track of a ball piston pump based on UG, the method comprising steps S101 to S104, wherein:

[0064] Step S101: Establish a coordinate system based on the stator track structure, and construct a mathematical model of the curves within the stator track on the coordinate system;

[0065] It should be noted that geometric modeling is a prerequisite for UG CNC machining. Therefore, in order to generate the stator geometric model, a coordinate system is first established based on the stator track structure, and a mathematical model of the inner curve of the stator track is constructed on the coordinate system.

[0066] Specifically, in some embodiments, a stator track modeling coordinate system is established with the center of the stator track as the origin, the x-axis as the direction of the major semi-axis of the stator track, and the y-axis as the direction of the minor semi-axis of the stator track.

[0067] A mathematical model is constructed in the stator track modeling coordinate system according to the following formula:

[0068] ;

[0069] in, , , For the major semi-axis of the stator track, For the short semi-axis of the stator track, Let the radius of the ball plug be . For the stator track groove depth, for k The line connecting the point and the origin of the coordinate system x The included angle of the axis, k is the k point of the curve inside the stator track.

[0070] Step S102: Generate the inner curve of the stator track in UG software according to the mathematical model, generate the stator geometric model according to the inner curve of the stator track, and design the CNC machining process of the stator track and set the machining parameters according to the stator geometric model;

[0071] In this step, first let , , , , , , ; and order Substituting these parameters into the mathematical model, the ball piston pump parameters are set, and a mathematical expression for the stator track inner curve is constructed in UG software, thereby generating the stator track inner curve:

[0072] ;

[0073] ;

[0074] Where t is a built-in variable in the UG software, with a value range of 0 to 1; when t=0, When t=1, ; , Z kt These represent the x-axis coordinates, y-axis coordinates, z-axis coordinates, and Z-axis coordinates of point k at time t within the stator track curve. kt =0.

[0075] Furthermore, in some embodiments, with Using point k as the center, a circle is generated within the normal plane of the stator track curve, with the ball plug radius as the radius. This circle is then swept along the inner curve of the stator track to create the swept body of the ball plug along the inner curve of the stator track. Finally, the rotation sweep function of UG software is used to create the rotating body of the stator. This rotating body is then subjected to a Boolean operation (subtraction) with the swept body to obtain the stator geometric model, as shown below. Figure 2 As shown.

[0076] Furthermore, in some embodiments, given the concave "bowl"-shaped structure of the inner curve, the CNC machining process for the stator track is designed as follows: first, all surfaces except the stator track surface are machined using CNC turning, and then the stator track is machined using CNC milling on this blank. For machining parameter settings, a single-flute end mill (spherical cutter) is used for milling. During machining, the spherical cutter tip of the single-flute end mill maintains tangential contact with the stator track surface, machining along the streamline direction of the stator track surface. Although the single-flute end mill has low milling efficiency and the tool holder is subject to unilateral force, milling efficiency is not the primary concern during stator track machining. Single-flute end mills can eliminate manufacturing errors of multi-flute tools. In CNC machining, they use equal-height machining toolpaths or helical machining toolpaths to control the cutting edge load to be uniform at each machining point, which can make the machining quality of the stator track surface uniform. By setting the cutting edge radii R1 and R2 in the T-shaped cutter parameter table in UG software to the radius of a single-flute ball head, and setting the cutting edge length in the T-shaped cutter parameter table to twice the radius of the ball head, a spherical cutter head is formed.

[0077] For example, such as Figure 3 For example, the ball head radius of the single-edged end mill is set to 4 mm, the cutting edge length is 8 mm (twice the ball head radius), and its rotation diameter is 40 mm (this rotation radius does not exceed the minimum curvature radius of the stator track surface normal).

[0078] Step S103: Perform pre-rough milling on the concave structure of the stator track according to the first preset rule, perform pre-semi-finishing and pre-finishing on the curved surface of the stator track according to the second preset rule, and generate the stator track milling tool trajectory based on the pre-rough milling, pre-semi-finishing and pre-finishing.

[0079] In some embodiments, the first preset rule specifically involves: generating a first intersection plane, a second intersection plane, and a third intersection plane, wherein the second intersection plane is located between the first intersection plane and the third intersection plane; the first intersection plane, the second intersection plane, and the third intersection plane are all parallel to the stator track plane, the second intersection plane passes through the center of the stator track, and the height range of the first intersection plane and the third intersection plane does not exceed the width range at the shallowest depth of the stator track; calculating the intersection lines between the stator track and the first intersection plane, the second intersection plane, and the third intersection plane respectively to obtain the calculated contours of the first intersection plane, the second intersection plane, and the third intersection plane; and machining the stator geometry using the calculated contours as the 2D contours of UG software.

[0080] For example, such as Figure 4 As shown, the stator track blank after turning is clamped on the worktable of a three-axis CNC milling machine, with the "bowl" part of the stator track facing upwards. The programming zero point is set as the center of the stator track. Rough milling is performed in three layers: middle, upper, and lower. First, the concave groove is rough milled out. Three intersecting planes are constructed, corresponding to the second, first, and third intersecting planes. Then, using the UG section intersection line function, the intersection lines between the stator track and the three layers of sections are obtained, thus acquiring the calculated contours of the middle, upper, and lower layers. Using the obtained calculated contours as the UG 2D contour machining geometry, 2D contour machining is performed in the order of the middle, upper, and lower layers, leaving machining allowance, to complete the pre-rough milling of the concave curved surface of the stator track.

[0081] It should be noted that due to the concave side structure of the "bowl" shape, the semi-finish milling and finish milling of the stator track are difficult to perform using the conventional settings of UG software. The solution is to use the fixed contour milling CNC machining module in UG software (the tool is the aforementioned T-type cutter, and the tool axis is set to the Z-axis). In this process, in addition to the conventional UG operations, the following special treatments are also performed:

[0082] (1) Driving geometry:

[0083] In the UG fixed contour milling CNC machining module, the machining object is usually directly used as the machining geometry and drive geometry. However, for the stator track's annular concave structure, directly specifying the stator track model as the machining geometry can easily generate complex and dangerous toolpath trajectories. To obtain a suitable stator track toolpath, a machining method is adopted that directly specifies the drive geometry to generate the toolpath without specifying the machining geometry. The drive geometry is designed as follows:

[0084] First, establish a reference plane that passes through the major axis of the stator track and is perpendicular to it. Figure 4 The intersection of the reference plane and the stator track surface is determined. Then, using the UG curve extension function, this intersection line is extended to ensure that the toolpath calculation range of the UG software exceeds the actual stator track width. Finally, the extended intersection line is used along... Figure 4 The intersection path of the mid-section and the stator track is swept to obtain a complete swept surface that fits the stator track perfectly and has a width range greater than the actual stator track machining range.

[0085] Since there is no solid body as the machining geometry, it is impossible to use the "part allowance" function in the UG software's machining module for finishing. Therefore, in the UG modeling module, a surface is offset using the normal of the swept surface, and this offset surface is used as the driving geometry for the stator track fixed shaft contour milling, such as... Figure 5 (exist Figure 5 In the modeling module, the outer surface is a swept surface, and the inner surface is an offset surface. Then, the machining allowance is changed by modifying the offset distance of the offset surface in the modeling module, and the tool path is generated in the machining module to achieve pre-semi-finishing and pre-finishing of the stator track surface.

[0086] (2) Cutting mode:

[0087] Since the stator track and the rotor cylinder of the ball piston pump jointly constrain the movement of the ball piston, the streamlines and surface texture of the stator track should be consistent with the direction of ball piston movement along the stator track. Considering the annular bowl-shaped structure of the stator track, the ideal cutting mode is a contour machining mode with the machining direction being the same as the direction of ball piston movement, thus ensuring the surface texture meets the requirements of the stator track. However, using a contour machining mode to machine the stator track easily generates many unnecessary feed and retraction movements, severely affecting machining efficiency and making the toolpath unsafe.

[0088] Therefore, in order to meet the requirements of the stator track and take into account processing efficiency, such as Figure 6 As shown, a spiral toolpath cutting mode is adopted, with the spiral cutting direction consistent with the movement direction of the ball plug on the stator track. The spiral approximates the streamline requirements of the curved surface through multiple spiral turns. On the other hand, the spiral toolpath cutting mode is similar to the equal height machining mode, with uniform cutting load at each tool point and uniform machining quality at each point on the curved surface.

[0089] (3) Tool path parameter settings:

[0090] Since the semi-finishing and finishing of the stator track are achieved by changing the offset distance of the stator track offset surface, the cutting area is specified as the offset surface itself. Based on the annular structure of the stator track, the driving method adopts surface region driving, and the projection vector is set to a mode away from the straight line, which is the stator track axis. This ensures that the tool path driving points are uniform and consistent with the streamline requirements of the stator track surface. For example, the tool path parameter settings are as follows: Figure 7 As shown.

[0091] (4) Tool advance and retraction methods:

[0092] To ensure smooth and safe stator track helical entry and exit, a large central angle arc entry and exit cutting mode is adopted, with the central angle of the entry and exit arcs set to 180 degrees. The T-shaped cutter is then moved in an arc to near the center of the stator track before being lifted.

[0093] Step S104: Use UG toolpath to detect the stator track milling tool path. If the detection is qualified, perform roughing, semi-finishing and finishing of the stator track.

[0094] In this step, it is necessary to check whether the tool path matches the streamline of the stator track surface and whether it meets the requirements of the ball piston pump for the machining texture of the stator track surface. If the tool path matches the streamline of the stator track surface and meets the requirements of the ball piston pump for the machining texture of the stator track surface, the inspection is qualified, and the stator track roughing, semi-finishing and finishing can be carried out in sequence according to the pre-set process.

[0095] Furthermore, based on the aforementioned stator track semi-finishing and finishing process design and parameter settings, the final stator track milling tool path is generated in UG software, such as... Figure 8 (In order to see the path of the blade clearly, Figure 8 The toolpath with the spiral turns reduced to 10 is displayed. Then, the UG toolpath is used to verify the contact between the tool and the stator track (tangential contact). It can be seen that the tool path meets expectations, is smooth, and safe. Furthermore, to further check the correctness of the toolpath, [the following is a separate, unrelated section:] Figure 8 The toolpath is processed using the post-processing function of UG software to generate CNC code, which is then input into a CNC machine tool (Huazhong 8, V2.4, VMC650, Yunnan CNC Machine Tool Factory) for machining, and continuously modified. Figure 5 The offset distance of the offset surface is used for roughing, semi-finishing and finishing of the stator track. The actual machining results show that the CNC machining toolpath of the stator track based on UG is smooth and safe, the process is correct, and the tool trajectory matches the streamline of the stator track surface, which meets the requirements of the ball piston pump for the machining texture of the stator track surface.

[0096] In summary, this invention proposes a novel method for milling the stator track of a ball piston pump. First, a mathematical model is constructed based on the formula for the inner curve of the stator track. Then, based on this mathematical model, a mathematical expression for the inner curve of the stator track is constructed, thereby generating the inner curve of the stator track and establishing a 3D geometric model of the inner curve stator track of the ball piston pump. On this basis, the process design is carried out in conjunction with the structural characteristics and machining requirements of the stator track, setting the cutting tool, machining geometry, and toolpath driving geometry. The toolpath is rationally planned according to the streamline of the stator track surface. The machining allowance is adjusted by changing the offset surface distance of the stator track. This method overcomes the difficulty of machining the complex, laterally concave surface of the stator track, realizes UG-based milling of the ball piston pump stator track, and achieves seamless integration of CAD / CAM for the inner curve ball piston pump stator track, thus broadening the methods for stator track machining.

[0097] While embodiments of the present invention have been described in detail above, it will be apparent to those skilled in the art that various modifications and variations can be made to these embodiments. However, it should be understood that such modifications and variations fall within the scope and spirit of the invention as set forth in the claims. Furthermore, the invention described herein may have other embodiments and can be implemented or carried out in various ways.

Claims

1. A method for milling the stator track of a ball piston pump based on UG, characterized in that, The method includes: A coordinate system is established based on the stator track structure, and a mathematical model of the curves within the stator track is constructed on the coordinate system. Based on the mathematical model, the inner curve of the stator track is generated in UG software. Based on the inner curve of the stator track, the stator geometric model is generated. Based on the stator geometric model, the CNC machining process of the stator track is designed and the machining parameters are set. The stator track side concave structure is pre-rough milled according to the first preset rule, and the stator track curved surface is pre-semi-finished and pre-finished according to the second preset rule. The stator track milling tool trajectory is generated based on the pre-rough milling, pre-semi-finishing and pre-finishing. A first intersection plane, a second intersection plane, and a third intersection plane are generated, wherein the second intersection plane is located between the first intersection plane and the third intersection plane; The first, second, and third intersecting planes are all parallel to the stator track plane. The second intersecting plane passes through the center of the stator track. The height range of the first and third intersecting planes does not exceed the width range of the shallowest part of the stator track side concavity. The intersection lines between the stator track and the first, second, and third intersection planes are obtained respectively, and the calculated profiles of the first, second, and third intersection planes are obtained. The stator geometry is machined using the calculated profile as the 2D profile in UG software. Construct a reference plane that passes through the major axis of the stator track and is perpendicular to the second intersection plane. Find the intersection line between the reference plane and the surface of the stator track, and use the UG curve extension function to extend the intersection line to obtain the extended intersection line. The extended intersection line is swept along the path of the intersection line between the second intersection plane and the stator track to obtain a swept surface that fits the stator track and has a width range greater than the processing range of the stator track. Using the swept surface normal to offset a surface, the offset surface is used as the driving geometry for stator track fixed shaft contour milling. The machining allowance of the stator track is changed by modifying the offset distance of the offset surface in the modeling module. Then, the tool path is generated in the machining module to realize the pre-semi-finishing and pre-finishing of the stator track surface. The spiral toolpath cutting mode is adopted, and the spiral cutting direction is consistent with the direction of ball plug movement on the stator track. The driving method adopts curved area driving, and the projection vector is set to a mode that moves away from the straight line, which is the center line of the stator track axis. The large central angle arc entry and exit cutting mode is adopted, and the central angle of the entry and exit arcs is set to 180 degrees. The UG toolpath is used to detect the stator track milling tool path. If the detection is qualified, the stator track roughing, semi-finishing and finishing are performed.

2. The method for milling the stator track of a ball piston pump based on UG according to claim 1, characterized in that, The step of establishing a coordinate system based on the stator track structure and constructing a mathematical model of the curves within the stator track on the coordinate system includes: A coordinate system for modeling the stator track is established with the center of the stator track as the origin, the x-axis as the direction of the major semi-axis of the stator track, and the y-axis as the direction of the minor semi-axis of the stator track. A mathematical model is constructed in the stator track modeling coordinate system according to the following formula: ; in, , , For the major semi-axis of the stator track, For the short semi-axis of the stator track, Let the radius of the ball plug be . For the stator track groove depth, Let k be the angle between the line connecting point k and the origin and the x-axis, where k is the point k on the curve inside the stator track.

3. The method for milling the stator track of a ball piston pump based on UG according to claim 2, characterized in that, The stator track inner curve is generated in UG software according to the mathematical model; include: make , , , , , , ; And order Substituting these parameters into the mathematical model, the ball piston pump parameters are set, and a mathematical expression for the stator track inner curve is constructed in UG software: ； ； Where t is a built-in variable in the UG software, with a value range of 0 to 1; when t=0, When t=1, ; , Z kt These represent the x-axis coordinates, y-axis coordinates, z-axis coordinates, and Z-axis coordinates of point k at time t within the stator track curve. kt =0.

4. The method for milling the stator track of a ball piston pump based on UG according to claim 3, characterized in that, The stator geometric model is generated based on the curve within the stator track. include: by Point k is the center of the circle, and a circle is generated in the normal plane of the curve within the stator track with the radius of the ball plug as the radius. The circle is swept along the inner curve of the stator track to generate the swept body of the ball plug along the inner curve of the stator track; The stator's rotating body is created using the rotation and sweep function of UG software, and a Boolean subtraction operation is performed between the rotating body and the swept body to obtain the stator's geometric model.

5. The method for milling the stator track of a ball piston pump based on UG according to claim 4, characterized in that, The step of designing the CNC machining process for the stator track based on the stator geometric model and setting the machining parameters includes: Using CNC turning technology, all stator surfaces except the stator track surface are turned out, and the stator track is then CNC milled using these as blanks. The stator track is milled using a single-edged milling cutter. During the machining process, the spherical tip of the single-edged milling cutter always maintains a tangential contact mode with the curved surface of the stator track and is machined along the streamline direction of the curved surface of the stator track. The cutting edge radius in the T-shaped tool parameter table in UG software and All are set to single-flute end mill ball cutter radius, and the cutting edge length in the T-cutter parameter table is set to twice the ball cutter radius to form a spherical cutter head.

6. The method for milling the stator track of a ball piston pump based on UG according to claim 5, characterized in that, The method employs UG toolpath detection to determine the stator track milling tool path. If the detection is satisfactory, roughing, semi-finishing, and finishing of the stator track are performed; including: The test checks whether the tool path matches the streamline of the stator track surface and whether it meets the requirements of the ball piston pump for the machining texture of the stator track surface. If the tool path matches the streamline of the stator track surface and meets the requirements of the ball piston pump for the machining texture of the stator track surface, the test is qualified.

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