Error compensation method and five-axis machine tool

Abstract

The application provides an error compensation method and a five-axis machine tool. The method comprises the following steps: selecting a plane to be compensated from a detection jig installed on the five-axis machine tool; if the plane to be compensated is an opening plane, calculating initial coordinates of intersection points between the opening and the plane to be compensated according to the depth of the opening, the center coordinates and the plane equation of the reference surface of the detection jig; rotating the plane to be compensated through a first rotation angle and a second rotation angle; rotating the rotated plane to be compensated into a horizontal plane based on a first error angle and a second error angle calculated from a preset vector, the first rotation angle, the second rotation angle and the normal vector of the rotated plane to be compensated; and compensating the absolute coordinate system of the detection jig based on a positional error value calculated from the initial coordinates, the first error angle, the second error angle and the actual coordinates of the intersection points on the horizontal plane. By using the above method, the machine tool can be effectively compensated for errors and the machining precision of the five-axis machine tool can be improved.

Description

Technical Field

[0001] This application relates to the field of CNC machine tool technology, and in particular to an error compensation method and a five-axis machine tool. Background Technology

[0002] A five-axis machine tool is a machine tool capable of movement and rotation in multiple directions, enabling high-precision machining of complex workpieces. During the machining process using a five-axis machine tool, the rotational and linear axes may introduce errors. These errors can stem from factors such as the machine tool's structure, changes in the working environment, and material properties. Current five-axis machine tool technologies lack compensation algorithms, making it difficult to effectively compensate for machine tool errors, thus affecting the machining accuracy of the workpiece. Summary of the Invention

[0003] In view of the above, it is necessary to provide an error compensation method and a five-axis machine tool that can solve the technical problem that it is difficult to effectively compensate for machine tool errors, which leads to the impact on the machining accuracy of workpieces.

[0004] On one hand, this application provides an error compensation method applied to a five-axis machine tool. The five-axis machine tool has a calibrated testing fixture mounted on its surface. The testing fixture includes multiple reference planes parallel to the coordinate axes of the machine tool coordinate system, each reference plane being parallel to a coordinate axis plane. The method includes: selecting any plane of the testing fixture as the plane to be compensated; obtaining a first rotation angle and a second rotation angle of the plane to be compensated, the first rotation angle corresponding to a first rotation axis of the five-axis machine tool, and the second rotation angle corresponding to a second rotation axis of the five-axis machine tool; if the plane to be compensated is an open hole, measuring the center coordinates of the center point within the hole of the plane to be compensated; calculating the intersection coordinates of the intersection point between the central axis of the hole and the plane to be compensated based on the depth of the hole and the center coordinates; calculating the projection distance between the intersection point and each reference plane based on the intersection coordinates and the plane equation of each reference plane; determining the initial coordinates of the intersection point based on multiple projection distances; and controlling the first rotation axis through the first rotation angle. The system rotates, and controls the second rotation axis to rotate via the second rotation angle, causing the plane to be compensated to rotate. The coordinates of multiple points on the rotated plane are measured, and the normal vector of the rotated plane is calculated based on the coordinates of these points. Based on the preset vector, the first rotation angle, the second rotation angle, and the normal vector, a first error angle corresponding to the first rotation axis and a second error angle corresponding to the second rotation axis are calculated. The first rotation axis is controlled to rotate via the first error angle, and the second rotation axis is controlled to rotate via the second error angle, causing the rotated plane to be compensated to become a horizontal plane. The standard coordinates of the intersection point on the horizontal plane are calculated based on the initial coordinates of the intersection point, the first error angle, and the second error angle. The actual coordinates of the intersection point on the horizontal plane are measured, and the positional error value corresponding to the hole is calculated based on the standard coordinates and the actual coordinates. The absolute coordinate system of the detection fixture is compensated based on the positional error value.

[0005] In some embodiments of this application, the detection fixture is mounted on the disk surface of the second rotating shaft, and the center of the detection fixture is located at the rotation center of the second rotating shaft.

[0006] In some embodiments of this application, the step of calculating the first error angle of the plane to be compensated corresponding to the first rotation axis and the second error angle of the plane to be compensated corresponding to the second rotation axis based on the preset vector, the first rotation angle, the second rotation angle, and the normal vector includes: constructing a rotation matrix according to the first rotation angle, the first parameter corresponding to the first error angle, and the second parameter corresponding to the second error angle; establishing a parametric equation according to the preset vector, the rotation matrix, and the normal vector; solving the parametric equation to obtain the first parameter value of the first parameter and the second parameter value of the second parameter; calculating an updated first rotation angle according to the first parameter value and the first rotation angle; and calculating the first error angle and the second error angle based on the preset vector, the updated first rotation angle, the second rotation angle, and the normal vector.

[0007] In some embodiments of this application, the rotation matrix is ​​represented as:

[0008]

[0009] in, Represents the rotation matrix, θ represents the first rotation angle. A Represents the first parameter, θ C This refers to the second parameter.

[0010] In some embodiments of this application, the parametric equation is expressed as:

[0011]

[0012] in, Represents the rotation matrix, Denotes the normal vector. This represents the preset vector.

[0013] In some embodiments of this application, the method for calculating the standard coordinates includes:

[0014]

[0015]

[0016] Wherein, P1′ represents the standard coordinate, a represents the first error angle, X` represents the horizontal coordinate in the initial coordinate, Y` represents the vertical coordinate in the initial coordinate, Z` represents the vertical coordinate in the initial coordinate, and c represents the second error angle.

[0017] In some embodiments of this application, calculating the positional error value corresponding to the hole based on the standard coordinates and the actual coordinates includes: determining the difference between the standard coordinates and the actual coordinates as the positional error value.

[0018] In some embodiments of this application, the step of compensating the absolute coordinate system of the detection fixture based on the position error value includes: adjusting the origin of the absolute coordinate system according to the position error value.

[0019] In some embodiments of this application, controlling the first rotation axis to rotate by the first rotation angle and controlling the second rotation axis to rotate by the second rotation angle to rotate the plane to be compensated includes: generating CNC instructions based on the first rotation angle and the second rotation angle, and controlling the first rotation axis and the second rotation axis to rotate by executing the CNC instructions, thereby rotating the plane to be compensated.

[0020] On the other hand, this application provides a five-axis machine tool, the five-axis machine tool comprising: a memory for storing at least one instruction; and a controller for executing the at least one instruction to implement the error compensation method.

[0021] In the above implementation scheme, for each plane of the inspection fixture, a first error angle relative to the first rotation axis and a second error angle relative to the second rotation axis can be calculated. When machining is required on each plane of the inspection fixture or workpiece, the plane to be machined can be rotated to a horizontal plane, thereby improving the machining accuracy of the five-axis machine tool. When the plane of the inspection fixture or workpiece is an opening plane, the positional error value of each hole in the opening plane can also be calculated. When machining each hole in the opening plane of the workpiece, compensation of the absolute coordinate system of the inspection fixture based on the positional error value of each hole can further improve the machining accuracy of the five-axis machine tool. In addition, directly compensating the absolute coordinate system of the inspection fixture through the positional error value can reduce the program modification time, thereby increasing the machining speed. Attached Figure Description

[0022] Figure 1 This is a schematic diagram of a testing fixture after reference plane calibration provided in one embodiment of this application.

[0023] Figure 2 This is a flowchart of an error compensation method provided in an embodiment of this application.

[0024] Figure 3 This is a schematic diagram of the rotated plane to be compensated provided in an embodiment of this application.

[0025] Figure 4This is a schematic diagram of the plane to be compensated after being rotated again, according to an embodiment of this application.

[0026] Figure 5 This is a flowchart illustrating a method for calculating the first error angle and the second error angle according to an embodiment of this application.

[0027] Figure 6 This is a functional block diagram of an error compensation device provided in an embodiment of this application.

[0028] Figure 7 This is a schematic diagram of the structure of a CNC system for a five-axis machine tool provided in an embodiment of this application. Detailed Implementation

[0029] To make the objectives, technical solutions, and advantages of this application clearer, the application will be described in detail below with reference to the accompanying drawings and specific embodiments.

[0030] It should be noted that in this application, "at least one" means one or more, and "more than one" means two or more. "And / or" describes the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent: A alone, A and B simultaneously, or B alone, where A and B can be singular or plural. The terms "first," "second," "third," "fourth," etc. (if present) in the specification, claims, and drawings of this application are used to distinguish similar objects, not to describe a specific order or sequence.

[0031] In the embodiments of this application, the terms "exemplary" or "for example" are used to indicate that something is an example, illustration, or description. Any embodiment or design that is described as "exemplary" or "for example" in the embodiments of this application should not be construed as being more preferred or advantageous than other embodiments or design. Specifically, the use of the terms "exemplary" or "for example" is intended to present the relevant concepts in a specific manner.

[0032] A five-axis machine tool is a machine tool capable of movement and rotation in multiple directions, enabling high-precision machining of complex workpieces. During the machining process using a five-axis machine tool, the rotational and linear axes may introduce errors. These errors can stem from factors such as the machine tool's structure, changes in the working environment, and material properties. Current five-axis machine tool technologies lack compensation algorithms, making it difficult to effectively compensate for machine tool errors, thus affecting the machining accuracy of the workpiece.

[0033] To address the aforementioned technical problems, this application provides an error compensation method and a five-axis machine tool, which can effectively compensate for machine tool errors and improve the machining accuracy of the five-axis machine tool. The error compensation method provided in this application can be applied to one or more five-axis machine tools.

[0034] A five-axis machine tool includes five machining axes: a horizontal axis, a vertical axis, a longitudinal axis, and a vertical axis, as well as multiple rotary axes. These five machining axes form the coordinate axes of the machine tool's coordinate system. In this embodiment, the five-axis machine tool can be a cradle-type five-axis machine tool. A cradle-type five-axis machine tool refers to a machine tool whose table shape and movement resemble a cradle. Cradle-type five-axis machine tools can be further divided into AC cradle-type five-axis machine tools and AB cradle-type five-axis machine tools. In an AC cradle-type five-axis machine tool, the X-axis represents the horizontal axis, the Y-axis represents the vertical axis, and the Z-axis represents the longitudinal axis. The multiple rotary axes of the AC cradle-type five-axis machine tool include the A-axis and the C-axis. In an AB cradle-type five-axis machine tool, the X-axis represents the horizontal axis, the Y-axis represents the vertical axis, and the Z-axis represents the longitudinal axis. The multiple rotary axes of the AC cradle-type five-axis machine tool include the A-axis and the B-axis.

[0035] The X-axis is the horizontal axis of movement. By moving along the positive or negative X-axis, the workpiece is controlled to move horizontally. Additionally, the X-axis allows the tool to move laterally along the horizontal direction, controlling the cutting point on the workpiece during machining.

[0036] The Y-axis is the axis of vertical movement. By moving along the positive or negative Y-axis, the workpiece is controlled to move vertically. Additionally, the Y-axis allows the tool to move vertically up and down, controlling the workpiece's height adjustment.

[0037] The Z-axis is the axis that moves along the spindle direction. By moving along the positive or negative Z-axis, the workpiece is controlled to move along the Z-axis. In addition, the Z-axis can cause the tool to advance or retract along the spindle direction, which is used to control the depth of cut and the accuracy of the machined surface.

[0038] The A-axis is the axis that rotates around the X-axis and is used to control the tilt angle of the workpiece. By rotating the A-axis, the workpiece can be tilted, enabling cutting operations at different angles, such as beveling and chamfering.

[0039] The C-axis is an axis that rotates around the Z-axis and is used to control the rotation angle of the workpiece. By rotating the C-axis, the workpiece can be rotated in a plane perpendicular to the spindle, which is used to achieve cutting operations of circular or curved shapes, such as threading and arc machining.

[0040] The B-axis is the axis of rotation around the Y-axis. By rotating the B-axis, the workpiece can be rotated in a plane perpendicular to the horizontal. The B-axis can be used to achieve more degrees of freedom in machining, such as tilting and machining complex curved surfaces.

[0041] For ease of description, the error compensation method in this application embodiment will be described below using an AC cradle-type five-axis machine tool as an example. The five-axis machine tool has a calibrated inspection fixture mounted on its disk surface. The inspection fixture is mounted on the C-axis disk surface such that its center is located at the rotation center of the C-axis. The rotation center refers to the reference point used by the five-axis machine tool for detection and positioning, and can be considered as the machining origin. The five-axis machine tool includes an interface fixture that enables quick docking between the five-axis machine tool and the inspection fixture (product or workpiece) without affecting the machining of the inspection fixture (workpiece or product).

[0042] The inspection fixture comprises multiple reference planes parallel to the coordinate axes of the five-axis machine tool's coordinate system, with each reference plane parallel to one coordinate axis plane. The inspection fixture is designed to match the product (workpiece) to be processed and the clamping method of the five-axis machine tool. The inspection fixture may include open-hole planes and non-open-hole planes; open-hole planes may include one or more holes, while non-open-hole planes have no holes. The inspection fixture (workpiece or product) has a corresponding absolute coordinate system, which uses a preset reference point on the inspection fixture as its origin and is used to describe the position and orientation of the inspection fixture. The preset reference point can be set arbitrarily, and this application does not impose any restrictions on it.

[0043] For example, such as Figure 1 The diagram shown is a schematic diagram of a testing fixture after reference plane correction provided in an embodiment of this application. Figure 1 The inspection fixture has 15 planes (planes 1-4 and 14-15 are not shown due to angle), including three reference planes: reference plane A, reference plane B, and reference plane C. Reference plane A is parallel to the coordinate plane formed by the X and Y axes of the five-axis machine tool; reference plane B is parallel to the coordinate plane formed by the X and Z axes; and reference plane C is parallel to the coordinate plane formed by the Y and Z axes. After the inspection fixture is installed, reference plane A is horizontal, and the rotation angle of both axes A and C is 0°. Figure 1 In the diagram, the XC axis is the horizontal axis of the absolute coordinate system corresponding to the inspection fixture (for example, the absolute coordinate system can be the G355 coordinate system used to describe the position and orientation of the inspection fixture), the YC axis is the vertical axis of the absolute coordinate system, and the ZC axis is the vertical axis of the absolute coordinate system.

[0044] like Figure 2 The diagram shown is a flowchart of an error compensation method provided in an embodiment of this application. Depending on different needs, the order of the steps in the flowchart can be adjusted according to actual requirements, and some steps can be omitted. The execution subject of the method can be a five-axis machine tool.

[0045] S10, select any plane of the testing fixture as the plane to be compensated, and obtain the first rotation angle and the second rotation angle of the plane to be compensated. The first rotation angle corresponds to the first rotation axis, and the second rotation angle corresponds to the second rotation axis.

[0046] In an AC-type cradle-type five-axis machine tool, the first rotary axis can be the A-axis and the second rotary axis can be the C-axis; alternatively, in an AB-type cradle-type five-axis machine tool, the first rotary axis can be the A-axis and the second rotary axis can be the B-axis. The first and second rotation angles can be collectively referred to as the "theoretical composite angle" of the A-axis and C-axis, which are theoretical angles that allow the plane to be compensated to rotate to a horizontal plane. The first and second rotation angles can be preset or obtained through user input; this application does not impose any limitations on this. For example, the first rotation angle can be... The second rotation angle can be

[0047] In this embodiment, due to errors and other reasons, the theoretical first rotation angle and the second rotation angle are unlikely to make the plane to be compensated rotate into a true horizontal plane. Therefore, the A-axis is rotated by the first rotation angle and the C-axis is rotated by the second rotation angle so that after the plane to be compensated is rotated, the rotated plane to be compensated is only a theoretically horizontal plane.

[0048] S11. If the plane to be compensated is an open plane, measure the center coordinates of the center point inside the hole in the plane to be compensated, and calculate the intersection coordinates of the intersection point between the central axis of the hole and the plane to be compensated based on the depth of the hole and the center coordinates.

[0049] In some embodiments of this application, the plane of the testing fixture may include an open plane and a non-open plane. The open plane includes one or more holes, while the non-open plane does not include holes. The number of holes in each open plane can be one or more, and the holes can be circular or other shapes; this application does not limit the shape of the holes. The holes can be blind holes or other types of holes; this application does not limit the type of holes. The center point within the hole refers to the point where the central axis of the hole intersects with the bottom of the hole. For example, the open plane can be... Figure 1 The 5th, 6th, 7th and 13th planes in the diagram.

[0050] In some embodiments of this application, a five-axis machine tool can control the movement of one or more machining axes to bring the probe of the five-axis machine tool to the center point of the hole and trigger a measurement operation, thereby obtaining the center coordinates of the center point. The probe includes a trigger and a sensor, and the center coordinates of the center point can be obtained by contacting the center point or emitting a laser towards the center point. This application does not limit the measurement method of the probe.

[0051] In some embodiments of this application, the five-axis machine tool can add the vertical coordinate of the center coordinate to the depth of the hole to obtain the intersection coordinates of the intersection point. For example, if the center coordinate is P0(x0,y0,z0) and the depth of the hole is h, the intersection coordinates of the intersection point are P0(x0,y0,z0+h).

[0052] Since the rotation angles of the A-axis and C-axis of the five-axis machine tool are both 0° after the inspection fixture is installed, and the reference plane A is a horizontal plane, the center coordinates of the hole's center point are the coordinates collected when the rotation angles of the A-axis and C-axis are both 0°.

[0053] In other embodiments of this application, if the plane to be compensated is a holeless plane, the center coordinates of the center point inside the hole in the plane to be compensated are not measured, and the depth and center coordinates of the hole are used as the basis for compensation.

[0054] For ease of explanation, the calculation process of compensation error will be explained below using only a single plane to be compensated (e.g., the 5th plane) as an example.

[0055] S12, calculate the projected distance between the intersection point and each reference plane based on the intersection coordinates and the plane equation of each reference plane, and determine the initial coordinates of the intersection point based on the multiple projected distances.

[0056] In some embodiments of this application, the plane equation of each reference plane is calculated using the coordinates of multiple points on the reference plane or can be obtained by user input. The calculation method for the plane equation can be found in related technologies, and this application does not limit it.

[0057] The projection distance is the shortest distance from the intersection point to each reference plane. For example, continuing with the above embodiment, if the intersection coordinates are P0(x0,y0,z0+h), the plane equation of reference plane A is a. A x+b A y+c A z+d A The method for calculating the projected distance between the intersection point and the reference plane A can be found in formula (1):

[0058]

[0059] Where distance(P0,A) represents the projected distance between the intersection point and the reference plane A.

[0060] In this embodiment, if the origin of the absolute coordinate system corresponding to the detection fixture is located at the rotation center of the five-axis machine tool, the five-axis machine tool can determine the first projection distance distance(P0,C) between the intersection point and the reference plane C as the abscissa X` of the initial coordinate, determine the second projection distance distance(P0,B) between the intersection point and the reference plane B as the ordinate Y` of the initial coordinate, and determine the third projection distance distance(P0,A) between the intersection point and the reference plane A as the ordinate Z` of the initial coordinate, thereby obtaining the initial coordinate P0′(X`,Y`,Z`).

[0061] In other embodiments of this application, if the distance between the origin of the absolute coordinate system corresponding to the detection fixture and the rotation center of the five-axis machine tool is H, the five-axis machine tool can determine the first projection distance distance(P0,C) as the abscissa X` of the initial coordinate, determine the second projection distance distance(P0,B) as the ordinate Y` of the initial coordinate, and determine the difference H-distance(P0,A) between the distance H and the third projection distance distance(P0,A) as the ordinate Z` of the initial coordinate, thereby obtaining the initial coordinate P0′(X`,Y`,Z`.

[0062] S13, the first rotation axis is controlled to rotate by the first rotation angle, and the second rotation axis is controlled to rotate by the second rotation angle, so that the plane to be compensated rotates.

[0063] In this embodiment, the five-axis machine tool can generate numerical control (NC) instructions based on the first rotation angle and the second rotation angle, and control the first and second rotation axes to rotate by executing the NC instructions, thereby causing the plane to be compensated to rotate.

[0064] For example, if the plane to be compensated is the 5th plane, such as Figure 3 The image shown is a schematic diagram of the rotated plane to be compensated according to an embodiment of this application. From... Figure 3 As can be seen, by controlling the A-axis to rotate by a first rotation angle and controlling the C-axis to rotate by a second rotation angle, the fifth plane is not a horizontal plane after rotation.

[0065] S14, measure the coordinates of multiple points on the rotated plane to be compensated, and calculate the normal vector of the rotated plane to be compensated based on the coordinates of the multiple points.

[0066] In some embodiments of this application, the measured multiple points can be multiple non-collinear points on the rotated plane to be compensated. To calculate the normal vector, the number of points is greater than or equal to three. The method for measuring the coordinates of the multiple points is essentially the same as the method for measuring the center coordinates of the center point, and therefore will not be repeated here.

[0067] For example, if the coordinates of three non-collinear points are measured to be P a =(x a ,y a ,z a ),P b =(x b ,y b ,z b ), P c =(x c ,y c ,z c The normal vector can be calculated using the following formula (2):

[0068] N=(x b -x a ,y b -y a ,z b -z a )×(x c -x a ,y c -y a ,z b -z c (2)

[0069] Where N represents the normal vector.

[0070] In this embodiment, by selecting the coordinates of multiple non-collinear points on the rotated plane to be compensated, the normal vector of the rotated plane to be compensated can be accurately calculated.

[0071] S15, based on the preset vector, the first rotation angle, the second rotation angle and the normal vector, calculate the first error angle of the plane to be compensated corresponding to the first rotation axis and the second error angle of the plane to be compensated corresponding to the second rotation axis.

[0072] In this embodiment, the first error angle refers to the difference between the ideal rotation angle (first rotation angle) of the first rotation axis required to rotate the plane to be compensated into a horizontal plane and the actual required rotation angle, and the second error angle refers to the difference between the ideal rotation angle (second rotation angle) of the second rotation axis required to rotate the plane to be compensated into a horizontal plane and the actual required rotation angle.

[0073] In this embodiment, for each plane to be compensated, a corresponding first error angle and a second error angle can be calculated. The first error angle is the compensation angle corresponding to the first rotation axis, and the second error angle is the compensation angle corresponding to the second rotation axis.

[0074] S16, the first rotation axis is rotated by controlling the first error angle, and the second rotation axis is rotated by controlling the second error angle, so that the plane to be compensated after rotation is rotated into a horizontal plane.

[0075] Since the first error angle refers to the difference between the ideal rotation angle (first rotation angle) of the first rotation axis required to rotate the plane to be compensated into a horizontal plane and the actual required rotation angle, and the second error angle refers to the difference between the ideal rotation angle (second rotation angle) of the second rotation axis required to rotate the plane to be compensated into a horizontal plane and the actual required rotation angle, by controlling the first rotation axis to rotate by the first error angle and controlling the second rotation axis to rotate by the second error angle, the plane to be compensated after rotation can be rotated again, so that the plane to be compensated after the second rotation can be a horizontal plane.

[0076] For example, if the plane to be compensated is the 5th plane, such as Figure 4 The image shown is a schematic diagram of the plane to be compensated after being rotated again, according to an embodiment of this application. From... Figure 4 As can be seen, by controlling the A-axis to rotate by a first error angle based on the first rotation angle, and by controlling the C-axis to rotate by a second error angle based on the second rotation angle, the plane to be compensated 5 can be rotated into a horizontal plane (a true horizontal plane).

[0077] In some embodiments of this application, the first rotation axis is controlled to rotate by a first error angle, and the second rotation axis is controlled to rotate by a second error angle, so that the plane to be compensated rotates to a horizontal plane after rotation. This is essentially the same as the rotation of the plane to be compensated by controlling the first rotation axis to rotate by a first rotation angle and the second rotation axis to rotate by a second rotation angle. Therefore, this application will not repeat the description.

[0078] In this embodiment, the first rotation axis is controlled to rotate by a first error angle, and the second rotation axis is controlled to rotate by a second error angle. This can compensate for the first and second rotation axes, so that the plane to be compensated after rotation is rotated into a horizontal plane, thus achieving error compensation for the first and second rotation axes.

[0079] In other embodiments of this application, after controlling the rotation of the first rotating axis by the first error angle and the rotation of the second rotating axis by the second error angle, the probe (see reference) can be used first. Figure 4The probe in the middle measures the coordinates of multiple points on the plane to be compensated (e.g., the fifth plane) after the second rotation, and determines whether the plane to be compensated after the second rotation is a horizontal plane based on the measured coordinates. This determines whether the first error angle and the second error angle are accurate (precise), so that the first and second rotation axes can be compensated again when the plane to be compensated after the second rotation is not a horizontal plane. The determination of whether the plane to be compensated after the second rotation is a horizontal plane based on the measured coordinates can refer to relevant technologies, and this application does not limit this.

[0080] S17. Calculate the standard coordinates of the intersection point on the horizontal plane based on the initial coordinates of the intersection point, the first error angle, and the second error angle.

[0081] In this embodiment, the formula for calculating the standard coordinates can be found in formulas (3)-(4):

[0082]

[0083]

[0084] Where P1′ represents the standard coordinate, a represents the first error angle, X` represents the x-coordinate in the initial coordinate system, Y` represents the y-coordinate in the initial coordinate system, Z` represents the y-coordinate in the initial coordinate system, and c represents the second error angle.

[0085] S18, measure the actual coordinates of the intersection point on the horizontal plane, and calculate the position error value corresponding to the hole based on the standard coordinates and the actual coordinates.

[0086] In some embodiments of this application, the position error value refers to the difference between the actual position (actual coordinates) of the hole and the corresponding ideal position (standard coordinates).

[0087] If the plane to be compensated is an open plane with multiple holes, then each hole corresponds to an actual coordinate and a standard coordinate. The five-axis machine tool can determine the positional error value corresponding to each hole by the difference between each standard coordinate and its corresponding actual coordinate, or by determining the positional error value corresponding to each hole by the difference between each actual coordinate and its corresponding standard coordinate. This application does not limit the calculation method for the positional error value of each hole.

[0088] The positional error value for each hole includes a first positional error value relative to the horizontal axis (X-axis), a second positional error value relative to the vertical axis (Y-axis), and a third positional error value corresponding to the vertical axis (Z-axis). For example, the first positional error value can be the difference between the horizontal coordinate of each standard coordinate and the corresponding actual coordinate, the second positional error value can be the difference between the vertical coordinate of each standard coordinate and the corresponding actual coordinate, and the third positional error value can be the difference between the vertical coordinate of each standard coordinate and the corresponding actual coordinate.

[0089] S19, based on the position error value, compensates for the absolute coordinate system of the inspection fixture.

[0090] In some embodiments of this application, an absolute coordinate system (e.g., Figure 1 The G355 coordinate system in this application is a coordinate system with a preset reference point on the inspection fixture (product or workpiece) as its origin, used to describe the position and orientation of the inspection fixture. The preset reference point can be set by the user, and this application does not impose any restrictions on it.

[0091] In some embodiments of this application, the compensation of the absolute coordinate system of the inspection fixture by the five-axis machine tool based on the compensation error includes: adjusting the origin of the absolute coordinate system according to each position error value.

[0092] In this embodiment, each plane to be compensated has a corresponding first error angle and a second error angle. If the plane to be compensated is an open plane, the position error value corresponding to each hole on the plane to be compensated can also be calculated.

[0093] In the above implementation scheme, for each plane of the inspection fixture, a first error angle relative to the first rotation axis and a second error angle relative to the second rotation axis can be calculated. When machining is required on each plane of the inspection fixture or workpiece, the plane to be machined can be rotated to a horizontal plane, thereby improving the machining accuracy of the five-axis machine tool. When the plane of the inspection fixture or workpiece is an opening plane, the positional error value of each hole in the opening plane can also be calculated. When machining each hole in the opening plane of the workpiece, compensation of the absolute coordinate system of the inspection fixture based on the positional error value of each hole can further improve the machining accuracy of the five-axis machine tool. In addition, directly compensating the absolute coordinate system of the inspection fixture through the positional error value can reduce the program modification time, thereby increasing the machining speed.

[0094] like Figure 5 The diagram shown is a flowchart of a method for calculating the first error angle and the second error angle according to an embodiment of this application.

[0095] S161, construct a rotation matrix based on the first rotation angle, the first parameter corresponding to the first error angle, and the second parameter corresponding to the second error angle.

[0096] In this embodiment, the rotation matrix can be expressed as formula (5) as shown below:

[0097]

[0098] in, Represents the rotation matrix. θ represents the first rotation angle. A Represents the first parameter, θ C This indicates the second parameter.

[0099] S162, establish the parametric equation based on the preset vector, rotation matrix and normal vector.

[0100] In this embodiment, the parametric equation can be expressed as formula (6) as shown below:

[0101]

[0102] in, Represents the rotation matrix. Represents the normal vector. This represents a preset vector.

[0103] S163, solve the parametric equation to obtain the first parameter value of the first parameter and the second parameter value of the second parameter.

[0104] In this embodiment, since the rotation matrix includes a first parameter and a second parameter, the first parameter value and the second parameter value can be obtained by simplifying and solving the above.

[0105] S164, Calculate the updated first rotation angle based on the first parameter value and the first rotation angle.

[0106] In some embodiments of this application, a five-axis machine tool can determine the difference between a first rotation angle and a first parameter value as an updated first rotation angle.

[0107] In this embodiment, since there is an error in the first rotation angle, the difference between the first rotation angle and the first parameter value is determined as the updated first rotation angle, which can reduce the error of the updated first rotation angle.

[0108] S165, based on the preset vector, the updated first rotation angle, the second rotation angle, and the normal vector, calculate the first error angle and the second error angle.

[0109] In this embodiment, the calculation methods for the first error angle and the second error angle are basically the same as the calculation methods for the first parameter value and the second parameter value, so this application will not repeat the description.

[0110] like Figure 6 The diagram shown is a functional block diagram of an error compensation device provided in an embodiment of this application. The error compensation device 11 includes a selection unit 110, an acquisition unit 111, a measurement unit 112, a calculation unit 113, a determination unit 114, a control unit 115, and a compensation unit 116. The module / unit referred to in this application refers to a module / unit capable of being... Figure 7 The controller 102 acquires a series of computer-readable instruction segments that are capable of performing a fixed function, and these segments are stored in... Figure 7 The memory 101 is used for this purpose. In this embodiment, the functions of each module / unit will be described in detail in subsequent embodiments.

[0111] Selection unit 110 is used to select any plane of the detection fixture as the plane to be compensated.

[0112] The acquisition unit 111 is used to acquire the first rotation angle and the second rotation angle of the plane to be compensated, wherein the first rotation angle corresponds to the first rotation axis of the five-axis machine tool and the second rotation angle corresponds to the second rotation axis of the five-axis machine tool.

[0113] The measuring unit 112 is used to measure the center coordinates of the center point inside the hole in the plane to be compensated if the plane to be compensated is an open plane, and to calculate the intersection coordinates of the intersection point between the central axis of the hole and the plane to be compensated based on the depth of the hole and the center coordinates.

[0114] The calculation unit 113 is used to calculate the projected distance between the intersection point and each reference plane based on the intersection coordinates and the plane equation of each reference plane.

[0115] The determining unit 114 is used to determine the initial coordinates of the intersection point based on multiple projection distances.

[0116] The control unit 115 is used to control the first rotation axis to rotate by the first rotation angle and to control the second rotation axis to rotate by the second rotation angle, so as to rotate the plane to be compensated.

[0117] The measuring unit 112 is also used to measure the coordinates of multiple points on the plane to be compensated after rotation.

[0118] The calculation unit 113 is also used to calculate the normal vector of the rotated plane to be compensated based on the coordinates of the plurality of points;

[0119] The calculation unit 113 is also used to calculate, based on the preset vector, the first rotation angle, the second rotation angle and the normal vector, the first error angle of the plane to be compensated corresponding to the first rotation axis and the second error angle of the plane to be compensated corresponding to the second rotation axis.

[0120] The control unit 115 is also used to control the first rotating axis to rotate by the first error angle and to control the second rotating axis to rotate by the second error angle, so that the rotated plane to be compensated is rotated into a horizontal plane.

[0121] The calculation unit 113 is also used to calculate the standard coordinates of the intersection point on the horizontal plane based on the initial coordinates of the intersection point, the first error angle, and the second error angle.

[0122] The measuring unit 112 is also used to measure the actual coordinates of the intersection point on the horizontal plane.

[0123] The calculation unit 113 is also used to calculate the position error value corresponding to the hole based on the standard coordinates and the actual coordinates;

[0124] The compensation unit 116 is also used to compensate the absolute coordinate system of the detection fixture based on the position error value.

[0125] In some embodiments of this application, in addition to the five machining axes mentioned above, the five-axis machine tool includes a numerical control system, wherein the numerical control system in the five-axis machine tool can be a computerized numerical control (CNC) system. For example, as... Figure 7 The diagram shown is a structural schematic of the CNC system of a five-axis machine tool provided in an embodiment of this application. Figure 7 The numerical control system 10 may include a memory 101, a controller 102, a driver 103, a motor 104, and a sensor 105.

[0126] Memory 101 may include one or more random access memory (RAM) and one or more non-volatile memory (NVM). The RAM can be directly read and written by the controller 102, and can be used to store executable programs (e.g., machine instructions) of other running programs, as well as user and application data. The RAM may include static random-access memory (SRAM), dynamic random access memory (DRAM), synchronous dynamic random access memory (SDRAM), double data rate synchronous dynamic random access memory (DDR SDRAM), etc.

[0127] Non-volatile memory can also store executable programs and user and application data, and can be pre-loaded into random access memory for direct reading and writing by the controller 102. Non-volatile memory can include disk storage devices and flash memory.

[0128] Memory 101 is used to store one or more computer programs. The one or more computer programs are configured to be executed by controller 102. The one or more computer programs include multiple instructions that, when executed by controller 102, can implement an error compensation method executed on CNC system 10.

[0129] Controller 102 is the control center of CNC system 10. Controller 102 may include a CNC controller and a programmable logic controller (PLC). The CNC controller is the main control device of the CNC system, used to receive or generate machining instructions and convert them into electrical signals to control various drive systems, realizing the movement and machining operations of the machine tool. The programmable logic controller is a digital computer specifically designed for automated control. It performs calculations and decisions through preset logic programs, and controls different actions and processes of the machine tool based on input signals (such as sensor signals) and current state judgment conditions. For example, during tool changing, the programmable logic controller can monitor the tool position signal and execute the corresponding tool changing program.

[0130] The driver 103 drives the motors along each axis, enabling them to perform precise position control according to instructions sent from the control center. The driver communicates with the controller 102, receiving position instructions from the controller 102 and converting the received instructions into current or voltage signals to drive the motors for precise position control, thereby realizing multi-axis linkage control of the five-axis machine tool.

[0131] Motor 104 converts electrical energy into mechanical energy through a helical transmission device on its rotating shaft, driving the workpiece or tool to perform linear or rotary motion along different machining axes. This enables multi-axis linkage motion of a five-axis machine tool, allowing the machining axes to complete complex machining operations. Furthermore, motor 104, in conjunction with position sensors such as encoders, can sense the position information of each machining axis in real time and feed this information back to controller 102. In addition, motor 104 can receive signals from controller 102, quickly start and stop according to received commands, and perform smooth acceleration and deceleration control as needed. This helps to avoid impacts and vibrations during workpiece machining, improving workpiece surface quality and machining accuracy.

[0132] Sensor 105 is used to monitor the actual position information of each machining operation and feeds this information back to controller 102 so that the CNC system can perform position control on motor 104. Sensor 105 includes, but is not limited to, encoders and linear encoders. In addition, sensor 105 can also be used to monitor the temperature of various machine tool components, including motor 104, spindle, inspection fixture, and workpiece, so as to keep the machine tool's operating temperature within a suitable range and avoid machining errors caused by temperature changes.

[0133] It is understood that the structures illustrated in the embodiments of this application do not constitute a specific limitation on the CNC system 10. In other embodiments of this application, the CNC system 10 may include more or fewer components than illustrated, or combine some components, or split some components, or have different component arrangements. The illustrated components may be implemented in hardware, software, or a combination of software and hardware.

[0134] This application also provides a computer-readable storage medium storing a computer program, which includes program instructions. When the program instructions are executed, the method implemented can refer to the methods in the above embodiments of this application.

[0135] The computer-readable storage medium can be the internal memory of the CNC system described in the above embodiments, such as the hard disk or memory of the CNC system. Alternatively, the computer-readable storage medium can be an external storage device of the CNC system, such as a plug-in hard disk, Smart Media Card (SMC), Secure Digital (SD) card, or Flash Card equipped on the CNC system.

[0136] In some embodiments, a computer-readable storage medium may include a stored program area and a stored data area, wherein the stored program area may store an operating system, an application program required for at least one function, etc.; and the stored data area may store data created based on the use of the CNC system, etc.

[0137] In the above embodiments, the descriptions of each embodiment have different focuses. For parts that are not described in detail or recorded in a certain embodiment, please refer to the relevant descriptions of other embodiments.

[0138] Those skilled in the art will recognize that the units and algorithm steps of the various examples described in conjunction with the embodiments disclosed herein can be implemented in electronic hardware, or a combination of computer software and electronic hardware. Whether these functions are implemented in hardware or software depends on the specific application and design constraints of the technical solution. Those skilled in the art can use different methods to implement the described functions for each specific application, but such implementation should not be considered beyond the scope of this application.

[0139] The above embodiments are only used to illustrate the technical solutions of this application, and are not intended to limit them. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of this application, and should all be included within the protection scope of this application.

Claims

1. An error compensation method applied to a five-axis machine tool, characterized in that, The five-axis machine tool has a testing fixture mounted on its disc surface after reference surface calibration. The testing fixture includes multiple reference surfaces parallel to the coordinate axis planes of the machine tool coordinate system of the five-axis machine tool. Each reference surface is parallel to a coordinate axis plane. The method includes: Select any plane of the detection fixture as the plane to be compensated, and obtain the first rotation angle and the second rotation angle of the plane to be compensated. The first rotation angle corresponds to the first rotation axis of the five-axis machine tool, and the second rotation angle corresponds to the second rotation axis of the five-axis machine tool. If the plane to be compensated is an open plane, measure the center coordinates of the center point inside the hole of the plane to be compensated, and calculate the intersection coordinates of the intersection point between the central axis of the hole and the plane to be compensated based on the depth of the hole and the center coordinates. Based on the intersecting coordinates and the plane equation of each reference plane, calculate the projected distance between the intersection point and each reference plane, and determine the initial coordinates of the intersection point based on multiple projected distances; The first rotation axis is controlled to rotate by the first rotation angle, and the second rotation axis is controlled to rotate by the second rotation angle, so that the plane to be compensated rotates. Measure the coordinates of multiple points on the rotated plane to be compensated, and calculate the normal vector of the rotated plane to be compensated based on the coordinates of the multiple points; Based on a preset vector, a first rotation angle, a second rotation angle, and a normal vector, the calculation of a first error angle of the plane to be compensated corresponding to the first rotation axis and a second error angle of the plane to be compensated corresponding to the second rotation axis includes: constructing a rotation matrix based on the first rotation angle, a first parameter corresponding to the first error angle, and a second parameter corresponding to the second error angle; establishing a parametric equation based on the preset vector, the rotation matrix, and the normal vector; solving the parametric equation to obtain a first parameter value of the first parameter and a second parameter value of the second parameter; calculating an updated first rotation angle based on the first parameter value and the first rotation angle; and calculating the first error angle and the second error angle based on the preset vector, the updated first rotation angle, the second rotation angle, and the normal vector. The first rotation axis is rotated by controlling the first error angle, and the second rotation axis is rotated by controlling the second error angle, so that the rotated plane to be compensated is rotated into a horizontal plane. Calculate the standard coordinates of the intersection point on the horizontal plane based on the initial coordinates of the intersection point, the first error angle, and the second error angle; Measure the actual coordinates of the intersection point on the horizontal plane, and calculate the positional error value corresponding to the hole based on the standard coordinates and the actual coordinates; Based on the position error value, the absolute coordinate system of the detection fixture is compensated; The method for calculating the standard coordinates includes: ； ； in, Represents the standard coordinates, This represents the first error angle. This represents the x-coordinate in the initial coordinate system. This represents the ordinate in the initial coordinate system. This represents the vertical coordinate in the initial coordinate system. This represents the second error angle.

2. The error compensation method as described in claim 1, characterized in that, The testing fixture is mounted on the disk surface of the second rotating shaft, and the center of the testing fixture is located at the rotation center of the second rotating shaft.

3. The error compensation method as described in claim 1, characterized in that, The rotation matrix is ​​represented as: ； in, Represents the rotation matrix, This represents the first rotation angle. This represents the first parameter. This refers to the second parameter.

4. The error compensation method as described in claim 1, characterized in that, The parametric equation is expressed as: ； in, Represents the rotation matrix, Denotes the normal vector. This represents the preset vector.

5. The error compensation method as described in claim 1, characterized in that, The step of calculating the positional error value corresponding to the hole based on the standard coordinates and the actual coordinates includes: The difference between the standard coordinates and the actual coordinates is determined as the position error value.

6. The error compensation method as described in claim 1 or 5, characterized in that, The compensation of the absolute coordinate system of the detection fixture based on the position error value includes: The origin of the absolute coordinate system is adjusted based on the position error value.

7. The error compensation method as described in claim 1, characterized in that, The step of controlling the rotation of the first rotation axis by the first rotation angle and controlling the rotation of the second rotation axis by the second rotation angle to rotate the plane to be compensated includes: Numerical control commands are generated based on the first rotation angle and the second rotation angle, and the first rotation axis and the second rotation axis are controlled to rotate by executing the numerical control commands, so that the plane to be compensated rotates.

8. A five-axis machine tool, characterized in that, The five-axis machine tool includes: Memory, storing at least one instruction; and The controller executes the at least one instruction to implement the error compensation method as described in any one of claims 1 to 7.

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