CN116619060A - Dynamically adjustable seven-axis workbench and method capable of eliminating nonlinear errors of curved surface machining - Google Patents
Dynamically adjustable seven-axis workbench and method capable of eliminating nonlinear errors of curved surface machining Download PDFInfo
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- CN116619060A CN116619060A CN202310858810.XA CN202310858810A CN116619060A CN 116619060 A CN116619060 A CN 116619060A CN 202310858810 A CN202310858810 A CN 202310858810A CN 116619060 A CN116619060 A CN 116619060A
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B23—MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
- B23Q—DETAILS, COMPONENTS, OR ACCESSORIES FOR MACHINE TOOLS, e.g. ARRANGEMENTS FOR COPYING OR CONTROLLING; MACHINE TOOLS IN GENERAL CHARACTERISED BY THE CONSTRUCTION OF PARTICULAR DETAILS OR COMPONENTS; COMBINATIONS OR ASSOCIATIONS OF METAL-WORKING MACHINES, NOT DIRECTED TO A PARTICULAR RESULT
- B23Q1/00—Members which are comprised in the general build-up of a form of machine, particularly relatively large fixed members
- B23Q1/25—Movable or adjustable work or tool supports
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B23—MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
- B23Q—DETAILS, COMPONENTS, OR ACCESSORIES FOR MACHINE TOOLS, e.g. ARRANGEMENTS FOR COPYING OR CONTROLLING; MACHINE TOOLS IN GENERAL CHARACTERISED BY THE CONSTRUCTION OF PARTICULAR DETAILS OR COMPONENTS; COMBINATIONS OR ASSOCIATIONS OF METAL-WORKING MACHINES, NOT DIRECTED TO A PARTICULAR RESULT
- B23Q15/00—Automatic control or regulation of feed movement, cutting velocity or position of tool or work
- B23Q15/20—Automatic control or regulation of feed movement, cutting velocity or position of tool or work before or after the tool acts upon the workpiece
- B23Q15/22—Control or regulation of position of tool or workpiece
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
- Y02P90/00—Enabling technologies with a potential contribution to greenhouse gas [GHG] emissions mitigation
- Y02P90/02—Total factory control, e.g. smart factories, flexible manufacturing systems [FMS] or integrated manufacturing systems [IMS]
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Abstract
The invention discloses a dynamic adjustable seven-axis workbench and a method capable of eliminating nonlinear errors of curved surface machining. The invention comprises a circle center positioning workbench with two degrees of freedom, a reverse adjusting workbench with three degrees of freedom and a workpiece posture adjusting workbench with two degrees of freedom. The invention is suitable for processing complex curved surface parts. Firstly, a tool space file of a curved surface workpiece, namely a space curve, is scattered into a micro plane curve, and then the plane curve is scattered into a plurality of sections of plane arcs. The workpiece posture adjustment workbench is adjusted to enable the plane curve to rotate to a horizontal plane, the circle center positioning workbench is adjusted to achieve circle center positioning of the plane arc by the circle center position of the plane arc to be processed, and the cutter position point position of the gantry five-axis linkage machine tool is adjusted by the radius of the plane arc to be processed. The invention uses the circular arc to fit the curve, improves the machining precision, keeps the tool position of the tool unchanged in the machining process, and eliminates nonlinear errors generated by the motion of the double rotating shafts in principle.
Description
Technical Field
The invention relates to a machine tool workbench, in particular to a dynamic adjustable seven-axis workbench capable of eliminating nonlinear errors of curved surface machining and a use method thereof.
Background
The interpolation method is adopted when the existing machine tool processes curved surfaces and curves, namely the interpolation is a process of determining the movement track of the cutter contact point of the cutter on the numerical control machine tool according to a certain method, adding a plurality of new intermediate points between known points of the track according to a given speed and track, and controlling a workpiece table and the cutter to pass through the intermediate points, so that the whole movement can be completed. In popular terms, the cutter is used for processing the curves to be processed in a broken line mode, namely, a plurality of tiny line segments and arcs are used for approaching the curves and curved surfaces to be processed.
The interpolation method includes linear interpolation, circular interpolation, spline interpolation, etc. The linear interpolation is as the name implies, and the tool completes interpolation between two points by linear motion; the circular arc interpolation is to calculate a point group approaching to an actual circular arc according to interpolation digital information between the end points, control a cutter to move along the points, and process a circular arc curve, but basically, a large number of tiny straight lines are used for processing the circular arc curve.
Since the fitting is approximate, there is a machining error theoretically, and linear interpolation generates a nonlinear systematic error. The three-axis machine tool cannot perform rotary machining without a rotary shaft. The four-axis linkage machine tool is provided with a rotating shaft, and can perform rotary machining, but because the rotating shaft is fixedly connected with the workpiece, the workpiece can only rotate around a fixed rotating shaft, and also can only machine an arc with a certain circle center. The five-axis linkage numerical control machine tool has two rotating shafts, and can process circular arcs with certain shapes, but the circular arcs with any circle centers and any radius at any position of a plane cannot be processed due to the self-structure limitation of the five-axis linkage numerical control machine tool.
Disclosure of Invention
The invention aims to overcome the defects of the prior art and provides a dynamic adjustable seven-axis workbench capable of eliminating nonlinear errors of curved surface machining. The workbench comprises a circle center positioning workbench with two degrees of freedom (translational axes X1 and Y1), a reverse adjusting workbench with three degrees of freedom (translational axes X2 and Y2 and a rotary shaft C1) and a workpiece posture adjusting workbench with two degrees of freedom (rotary shafts C2 and A2). The invention is particularly suitable for processing complex curved surface parts with complex shapes and high surface quality requirements. Firstly, a tool space file of a curved surface workpiece, namely a space curve, is scattered into a micro plane curve, and then the plane curve is scattered into a plurality of sections of plane arcs. And adjusting the workpiece posture adjustment workbench to enable the plane curve to rotate to a horizontal plane, adjusting the circle center positioning workbench to realize circle center positioning of the plane arc, and adjusting a cutter of the gantry five-axis linkage machine tool to determine the machining radius.
The technical scheme of the invention is as follows:
1. dynamic adjustable seven-axis workbench capable of eliminating nonlinear errors of curved surface machining
The dynamic adjustable seven-axis workbench comprises a circle center positioning workbench, a reverse adjusting workbench and a workpiece posture adjusting workbench, wherein the circle center positioning workbench is fixedly arranged on a machine tool frame, the reverse adjusting workbench is rotatably arranged on the circle center positioning workbench, the workpiece posture adjusting workbench is rotatably arranged on the reverse adjusting workbench, and a workpiece to be processed is fixedly arranged on the workpiece posture adjusting workbench.
The circle center positioning workbench comprises a circle center positioning workbench lower platform, a circle center positioning workbench middle platform and a circle center positioning workbench upper platform; the center positioning workbench lower table is fixedly arranged on the machine tool frame, the center positioning workbench middle table is slidably arranged on the center positioning workbench lower table, the center positioning workbench upper table is slidably arranged on the center positioning workbench middle table, the sliding direction of the center positioning workbench middle table on the center positioning workbench lower table is perpendicular to the sliding direction of the center positioning workbench upper table on the center positioning workbench middle table, and the reverse adjusting workbench is rotatably arranged on the center positioning workbench upper table.
The reverse adjustment workbench comprises a reverse adjustment workbench lower table, a reverse adjustment workbench middle table and a reverse adjustment workbench upper table; the lower table of the reverse adjusting workbench is rotatably arranged on the circle center positioning workbench, the middle table of the reverse adjusting workbench is slidably arranged on the lower table of the reverse adjusting workbench, the upper table of the reverse adjusting workbench is slidably arranged on the middle table of the reverse adjusting workbench, the sliding direction of the middle table of the reverse adjusting workbench on the lower table of the reverse adjusting workbench is perpendicular to the sliding direction of the upper table of the reverse adjusting workbench on the middle table of the reverse adjusting workbench, and the workpiece posture adjusting workbench is rotatably arranged on the upper table of the reverse adjusting workbench.
The workpiece posture adjustment workbench comprises a workpiece posture adjustment workbench lower platform and a workpiece posture adjustment workbench upper platform;
the workpiece posture adjustment workbench comprises a workpiece posture adjustment workbench, and is characterized in that an upwards extending mounting frame is arranged on the reverse adjustment workbench, a workpiece posture adjustment workbench lower table is rotatably mounted in the mounting frame of the reverse adjustment workbench upper table, a workpiece posture adjustment workbench upper table is rotatably mounted on the workpiece posture adjustment workbench lower table, a rotating shaft of the reverse adjustment workbench lower table is perpendicular to a rotating shaft of the workpiece posture adjustment workbench lower table, and the rotating shaft of the workpiece posture adjustment workbench lower table is perpendicular to and intersected with the rotating shaft of the workpiece posture adjustment workbench upper table.
When in the initial position, the rotating shaft of the reverse adjusting workbench is coaxial with the rotating shaft of the upper workbench of the workpiece posture adjusting workbench.
2. A method for using a dynamic adjustable seven-axis workbench capable of eliminating nonlinear errors of curved surface processing,
1) Dispersing all tool path space curves in the workpiece space curved surface into a plurality of corresponding tool path plane curves respectively; determining a plurality of approximate arcs corresponding to the plane curves of the tool tracks, and further calculating circle centers and radiuses corresponding to the approximate arcs; determining an initial tool path space curve and a corresponding initial tool path plane curve;
2) Fixedly mounting a workpiece to be processed on a workpiece posture adjustment workbench, fixedly mounting a dynamic adjustable seven-axis workbench on a gantry five-axis linkage machine tool, recovering to an initial position, and adjusting the workpiece posture adjustment workbench to enable the plane of the plane curve of the current tool track to coincide with the processing plane of the dynamic adjustable seven-axis workbench;
3) According to the circle center position and the radius corresponding to each approximate circular arc, adjusting the circle center positioning workbench and the cutter of the gantry five-axis linkage machine tool, and through the rotary motion between the reverse adjustment workbench and the circle center positioning workbench, generating relative motion between the cutter and a workpiece to be processed, and processing a current approximate circular arc on the workpiece to be processed, wherein the cutter position point of the cutter is kept unchanged in the current processing process, and the cutter axis vector is kept unchanged, so that the processing of the current approximate circular arc is completed;
4) The reverse adjusting workbench is reversely adjusted according to the translational movement of the circle center positioning workbench, so that the position of a workpiece to be processed and the position of a cutter are not changed, and then the reverse adjusting workbench is driven to perform rotary movement on the circle center positioning workbench, so that the cutter position and the cutter shaft vector of the cutter are respectively and independently changed, and the cutter is enabled to work to the next cutter position;
5) Repeating 3) -4) processing the corresponding approximate circular arcs and driving the tool to work to the next arrival point according to the circle center and the radius of the next approximate circular arc in the current tool path plane curve until all the approximate circular arcs in the current tool path plane curve are processed in a traversing way;
6) The gesture of the workpiece to be processed is adjusted by adjusting the workpiece gesture adjusting workbench, so that the processing surface of the dynamic adjustable seven-axis workbench coincides with the plane of the plane curve of the next tool path, and then the tool bit point is moved to the position of the first tool bit point of the plane curve of the current tool path;
7) Repeating 3) -6), processing the corresponding tool path plane curve according to the circle centers and the radiuses of all approximate arcs of the rest tool path plane curves in the current tool path space curve until the current tool path space curve is processed;
8) And 7) traversing the space curve of the rest tool path of the machining until the machining obtains an actual space curved surface, thereby obtaining the target workpiece.
In the workpiece space curved surface, each tool path space curve is discretized into a plurality of tool path plane curves by the following method:
each tool path space curve consists of a plurality of discrete tool position points, whether adjacent tool position points are located on the same plane or not is judged in sequence, and turning points between the two adjacent planes are determined, so that each plane is determined, and each tool path plane curve is formed by the tool position points in each plane.
In the 4), the reverse adjusting workbench is driven to perform rotary motion on the circle center positioning workbench, and the cutter position and the cutter shaft vector of the cutter are respectively and independently changed, so that the cutter works to the next cutter position, and the method specifically comprises the following steps:
the cutter shaft vector of the cutter at the position of the last cutter position is unchanged, the reverse adjusting workbench is driven to perform rotary motion on the circle center positioning workbench, so that the cutter moves to the position of the next cutter position, and then the cutter shaft vector of the cutter position of the cutter is changed on the premise that the position of the next cutter position is unchanged; or on the premise that the position of the last cutter position point is unchanged, the cutter shaft vector of the cutter position point of the cutter is changed, and then on the premise that the cutter shaft vector is kept unchanged, the reverse adjusting workbench is driven to perform rotary motion on the circle center positioning workbench, so that the cutter moves to the position of the next cutter position point.
In the step 2), the workpiece to be processed is a workpiece which is roughly processed by a gantry type five-axis linkage machine tool.
In the step 3), the position of the axis of the circle center positioning workbench is adjusted according to the circle center position corresponding to each approximate circular arc, so that the axis of the circle center positioning workbench is overlapped with the circle center of the approximate circular arc, the position of the cutter point of the gantry five-axis linkage machine tool is adjusted according to the radius corresponding to each approximate circular arc, the position of the cutter point is positioned on the arc line of the approximate circular arc, and the cutter and the workpiece to be processed generate relative motion and the current approximate circular arc is processed on the workpiece to be processed through the rotary motion between the reverse adjustment workbench and the circle center positioning workbench.
The beneficial effects of the invention are as follows:
the invention can process circular arcs with any circle center position and any radius on a plane within a certain range (the circle center position and the radius depend on the actual size of the workbench), and can process space curves and space curved surfaces, thereby overcoming the limitation that a five-axis linkage machine tool can only process straight lines and circular arcs with certain circle center positions.
The workbench eliminates nonlinear errors brought by interpolation algorithm of the five-axis linkage machine tool in theory, reduces machining errors, improves machining precision, meets the requirements of modern production, and is particularly suitable for machining complex curved surfaces with large curvature and small curvature radius.
Drawings
The invention is further described below with reference to the drawings and examples;
FIG. 1 is an overall schematic diagram of a dynamically adjustable seven-axis table of the present invention that eliminates non-linear errors in surface processing;
FIG. 2 is a schematic view of a workpiece attitude adjustment table according to the present invention;
FIG. 3 is a schematic view of a counter-adjustment table of the present invention;
FIG. 4 is a schematic view of a center positioning table according to the present invention;
FIG. 5 is a schematic diagram of a principle of generating nonlinear error;
FIG. 6 is a schematic diagram of the present invention for eliminating nonlinear errors;
FIG. 7 is a flow chart of a method for dynamically adjustable seven-axis table capable of eliminating non-linear errors in surface processing according to the present invention.
FIG. 8 is a flow chart of a method of using a dynamically adjustable seven-axis table of the present invention to eliminate non-linear errors in surface processing.
In the figure: the workpiece posture adjustment device comprises an upper table 1 of a workpiece posture adjustment workbench, a lower table 2 of the workpiece posture adjustment workbench, a reverse adjustment workbench upper table 3, a reverse adjustment workbench middle table 4, a reverse adjustment workbench lower table 5, a circle center positioning workbench upper table 6, a circle center positioning workbench middle table 7 and a circle center positioning workbench lower table 8.
Detailed Description
The invention will be described in further detail with reference to the accompanying drawings and specific examples. It should be understood that the detailed description and specific examples, while indicating and illustrating the invention, are not intended to limit the invention.
As shown in fig. 1, the dynamic adjustable seven-axis workbench comprises a circle center positioning workbench, a reverse adjusting workbench and a workpiece posture adjusting workbench, wherein the circle center positioning workbench, the reverse adjusting workbench and the workpiece posture adjusting workbench are coaxially arranged and are sequentially arranged in a stacked manner from bottom to top; the center positioning workbench is fixedly arranged on the machine tool frame, the reverse adjusting workbench and the parts above the reverse adjusting workbench are rotatably arranged on the center positioning workbench, the workpiece posture adjusting workbench and the parts above the workpiece posture adjusting workbench are rotatably arranged on the reverse adjusting workbench, and the workpiece to be processed is fixedly arranged on the workpiece posture adjusting workbench upper table 1.
As shown in fig. 4, the center positioning table includes a center positioning table lower table 8, a center positioning table middle table 7, and a center positioning table upper table 6; the center positioning workbench lower table 8 is fixedly arranged on a machine tool frame, the center positioning workbench middle table 7 is slidably arranged on the center positioning workbench lower table 8, the center positioning workbench upper table 6 is slidably arranged on the center positioning workbench middle table 7, the sliding direction (marked as Y1 direction) of the center positioning workbench middle table 7 on the center positioning workbench lower table 8 is perpendicular to the sliding direction (marked as X1 direction) of the center positioning workbench upper table 6 on the center positioning workbench middle table 7, and the reverse adjusting workbench lower table 5 of the reverse adjusting workbench is rotatably arranged on the center positioning workbench upper table 6.
As shown in fig. 3, the reverse adjustment table includes a reverse adjustment table lower stage 5, a reverse adjustment table middle stage 4, and a reverse adjustment table upper stage 3; the reverse adjustment table lower stage 5 is rotatably mounted on the center positioning table upper stage 6 of the center positioning table, the reverse adjustment table middle stage 4 is slidably mounted on the reverse adjustment table lower stage 5, the reverse adjustment table upper stage 3 is slidably mounted on the reverse adjustment table middle stage 4, the sliding direction (denoted as Y2 direction) of the reverse adjustment table middle stage 4 on the reverse adjustment table lower stage 5 is perpendicular to the sliding direction (denoted as X2 direction) of the reverse adjustment table upper stage 3 on the reverse adjustment table middle stage 4, and the workpiece posture adjustment table lower stage 2 of the workpiece posture adjustment table is rotatably mounted on the reverse adjustment table upper stage 3. In the initial position, the Y1 direction and the Y2 direction are in the same direction, and the X1 direction and the X2 direction are in the same direction.
As shown in fig. 2, the workpiece posture adjustment table includes a workpiece posture adjustment table lower stage 2 and a workpiece posture adjustment table upper stage 1; the workpiece posture adjustment workbench comprises a workpiece posture adjustment workbench, a workpiece posture adjustment workbench upper table 1, a workpiece posture adjustment workbench lower table 2, a workpiece posture adjustment workbench upper table 3 and a workpiece posture adjustment workbench upper table 2, wherein an upwards extending mounting frame is arranged on the reverse adjustment workbench upper table 3 of the reverse adjustment workbench, the workpiece posture adjustment workbench lower table 2 is rotatably mounted on the workpiece posture adjustment workbench lower table 2, a rotating shaft C1 of the reverse adjustment workbench lower table 5 of the reverse adjustment workbench is perpendicular to a rotating shaft A2 of the workpiece posture adjustment workbench lower table 2, and the rotating shaft A2 of the workpiece posture adjustment workbench lower table 2 is perpendicular to and intersected with the rotating shaft C2 of the workpiece posture adjustment workbench upper table 1. In the initial position, the rotation axis C1 of the reverse adjustment table lower stage 5 of the reverse adjustment table is coaxial with the rotation axis C2 of the workpiece posture adjustment table upper stage 1.
In specific implementation, the linear motion between the two working tables adopts spiral transmission, and the rotary motion between the two working tables adopts worm and gear transmission, but the linear motion is not limited to the two transmission modes.
As shown in fig. 7 and 8, the method comprises the steps of:
1) Dispersing all tool path space curves in the workpiece space curved surface generated by UG software into a plurality of corresponding tool path plane curves respectively; determining a plurality of approximate arcs corresponding to each cutter track plane curve (formed by a plurality of discrete curves), and further calculating circle centers and radiuses corresponding to the approximate arcs; determining an initial tool path space curve and a corresponding initial tool path plane curve;
in the space curved surface of the workpiece, each tool path space curve is discretized into a plurality of tool path plane curves by the following method:
each tool path space curve consists of a plurality of discrete tool position points, whether adjacent tool position points are located on the same plane or not is judged in sequence, and turning points between the two adjacent planes are determined, so that each plane is determined, and each tool path plane curve is formed by the tool position points in each plane. For example, three points that are not on the same straight line may uniquely define a plane, two adjacent planes share a middle point, two planes defined by the adjacent five knife locations are the same plane if the two adjacent planes are parallel, the five points are on the same plane, the adjacent five points are not on the same plane if the two adjacent planes are not parallel, and the third knife location (middle point) is the turning point of the two planes. Specifically, two adjacent knife location points form a knife location point vector, then the normal vector of a plane formed by three adjacent points is obtained by the two adjacent knife location point vectors, and then whether the five knife location points are knife location points on the same plane is judged by the two plane normal vectors formed by five adjacent knife location points.
2) The dynamic adjustable seven-axis workbench is fixedly arranged on a gantry five-axis linkage machine tool, a workpiece to be machined is clamped on a workpiece posture adjustment workbench by a clamp, namely the workpiece to be machined is fixedly arranged on a workpiece posture adjustment workbench upper table 1 of the workpiece posture adjustment workbench, the dynamic adjustable seven-axis workbench is adjusted to return to an initial position, namely the axis of a circle center positioning workbench lower table 8 is concentric with the axis of the circle center positioning workbench upper table 6, the axes of a reverse adjustment workbench upper table 3 and the axis of the workpiece posture adjustment workbench upper table 1 are arranged vertically upwards, the position of the workpiece is the initial position (shown in figure 1), and the workpiece posture adjustment workbench is adjusted so that the plane where the plane curve of the current tool track is located coincides with the machining surface (horizontal plane) of the dynamic adjustable seven-axis workbench;
in this embodiment, the workpiece to be processed is a workpiece rough processed by a gantry type five-axis linkage machine tool.
3) According to the position of the center of a circle corresponding to each approximate circular arc, the position of the axis of the center positioning workbench is adjusted, so that the axis of the center positioning workbench is overlapped with the center of the approximate circular arc, specifically, the center positioning workbench and the reverse adjusting workbench are adjusted, the workpiece is kept static, the axis of the center positioning workbench moves relative to the workpiece, the position of a cutter point of the gantry five-axis linkage machine tool is adjusted according to the radius corresponding to each approximate circular arc, the position of the cutter point is positioned on the arc line of the approximate circular arc, and the cutter and the workpiece to be processed can generate relative motion and process the current approximate circular arc on the workpiece to be processed through the rotary motion between the reverse adjusting workbench and the center positioning workbench (because the center positioning workbench can only process circular arcs with any center position and radius in a certain range on the water plane). The cutter position point of the cutter is kept unchanged in the current processing process, the cutter shaft vector is also kept unchanged, and the processing of the current approximate arc is completed;
4) The middle table 4 and the upper table 3 of the reverse adjusting workbench corresponding to the reverse adjusting workbench are reversely adjusted according to the translational movement of the middle table 7 and the upper table 6 of the center positioning workbench, so that the position of a workpiece to be processed and the position of a cutter are not changed, and errors caused by repeated positioning are avoided. Then the reverse adjusting workbench is driven to perform rotary motion on the circle center positioning workbench, and the cutter position and the cutter shaft vector of the cutter are respectively and independently changed, so that the cutter works to the next cutter position;
4) In the method, the reverse adjusting workbench is driven to perform rotary motion on the circle center positioning workbench, and the cutter position point and the cutter shaft vector of the cutter are respectively and independently changed, so that the cutter works to the next cutter position point, and the method specifically comprises the following steps:
the cutter shaft vector of the cutter is unchanged when the cutter is positioned at the position of the last cutter position i, the reverse adjusting workbench is driven to perform rotary motion on the circle center positioning workbench, so that the cutter moves to the position of the next cutter position i+1, and then the cutter shaft vector of the cutter is changed on the premise that the cutter position of the cutter is unchanged at the position of the next cutter position i+1; or on the premise that the position of the cutter position point i of the cutter is unchanged, changing the cutter shaft vector of the cutter, and then on the premise of keeping the cutter shaft vector unchanged, driving the reverse adjustment workbench to perform rotary motion on the circle center positioning workbench, so that the cutter moves to the position of the next cutter position point i+1.
In a linear interpolation system, the theoretical interpolation trajectory is a linear motion. When a rotational motion is added, such as:
in the actual machining process, the deviation between the curve and the theoretical interpolation track is called nonlinear error because of the inconsistency between the nonlinear motion of the five-axis linkage and the linear interpolation of the five-axis linkage numerical control system. As shown in fig. 5, the theoretical interpolation trajectory is a space straight line, but the actual processing trajectory is an irregular space curve.
When the cutter of the five-axis linkage machine tool moves from one cutter position point to another cutter position point, the cutter position point and the cutter axis vector of the cutter are changed, so that the translational shaft and the rotating shaft are required to move simultaneously, but the coupling movement of the translational shaft and the rotating shaft can generate nonlinear errors. In the processing process of the working table for processing the approximate circular arc, the rotary motion of the working table is reversely regulated to enable the workpiece and the cutter to generate relative rotary motion, and only the cutter position point of the cutter is required to be changed relative to the workpiece when the single approximate circular arc is processed, so that nonlinear errors are not generated. When a plurality of sections of approximate circular arcs are processed, respectively and independently changing the cutter position point and the cutter shaft vector of the cutter, for example, rotating the circle center positioning workbench to enable the cutter to move to the position of the cutter position point i+1 on the premise that the cutter position point i keeps the cutter shaft vector of the cutter unchanged, and then changing the cutter shaft vector of the cutter on the premise that the position of the cutter position point i+1 keeps the cutter position; or changing the cutter shaft vector of the cutter on the premise of keeping the position of the cutter position point i of the cutter unchanged, and then rotating the circle center positioning workbench to enable the cutter to move to the cutter position point i+1 on the premise of keeping the cutter shaft vector unchanged. In summary, in order to prevent the generation of nonlinear errors, the tool position and the arbor vector of the tool cannot be changed at the same time, as shown in fig. 6.
5) Repeating 3) -4) processing the corresponding approximate arc and driving the cutter to work to the next cutter point according to the circle center and the radius of the next approximate arc in the current cutter path plane curve until all the approximate arcs in the current cutter path plane curve are processed in a traversing way;
6) The workpiece posture adjustment workbench is adjusted by adjusting the workpiece posture adjustment workbench lower platform 2 and the workpiece posture adjustment workbench upper platform 1, so that the machining surface of the dynamic adjustable seven-axis workbench coincides with the plane of the plane curve of the next tool path, the tool position point on the workpiece can be changed, and if the tool position point of the gantry five-axis machine tool is changed along with the change of the tool position point of the workpiece, nonlinear errors can be generated, and therefore, the tool position point of the gantry five-axis machine tool needs to be changed first to exit machining and cannot interfere the rotation of the workpiece. When the posture of the workpiece is adjusted, moving the cutter locus to the position of the first cutter locus of the current cutter locus plane curve;
7) Repeating 3) -6), processing the corresponding tool path plane curve according to the circle centers and the radiuses of all approximate arcs of the rest tool path plane curves in the current tool path space curve until the current tool path space curve is processed;
8) And 7) traversing the space curve of the rest tool path until the actual space curve is obtained, and finishing the workpiece to obtain the target workpiece.
Therefore, the workbench needs to work together with a gantry type five-axis linkage machine tool, and the gantry type five-axis linkage machine tool performs rough machining firstly and then performs final finish machining by combining the workbench.
The above-described embodiments are intended to illustrate the present invention, not to limit it, and any modifications and variations made thereto are within the spirit of the invention and the scope of the appended claims.
Claims (10)
1. The dynamic adjustable seven-axis workbench is characterized by comprising a circle center positioning workbench, a reverse adjusting workbench and a workpiece posture adjusting workbench, wherein the circle center positioning workbench is fixedly arranged on a machine tool frame, the reverse adjusting workbench is rotatably arranged on the circle center positioning workbench, the workpiece posture adjusting workbench is rotatably arranged on the reverse adjusting workbench, and a workpiece to be processed is fixedly arranged on the workpiece posture adjusting workbench.
2. The dynamically adjustable seven-axis workbench capable of eliminating curved surface machining nonlinear errors according to claim 1, wherein the circle center positioning workbench comprises a circle center positioning workbench lower platform (8), a circle center positioning workbench middle platform (7) and a circle center positioning workbench upper platform (6); the center positioning workbench lower table (8) is fixedly arranged on the machine tool frame, the center positioning workbench middle table (7) is slidably arranged on the center positioning workbench lower table (8), the center positioning workbench upper table (6) is slidably arranged on the center positioning workbench middle table (7), the sliding direction of the center positioning workbench middle table (7) on the center positioning workbench lower table (8) is perpendicular to the sliding direction of the center positioning workbench upper table (6) on the center positioning workbench middle table (7), and the reverse adjusting workbench is rotatably arranged on the center positioning workbench upper table (6).
3. A dynamically adjustable seven-axis table capable of eliminating curved surface machining nonlinear errors according to claim 1, wherein the counter-adjustment table comprises a counter-adjustment table lower table (5), a counter-adjustment table middle table (4) and a counter-adjustment table upper table (3); the reverse adjustment workbench lower table (5) is rotatably mounted on the circle center positioning workbench, the reverse adjustment workbench middle table (4) is slidably mounted on the reverse adjustment workbench lower table (5), the reverse adjustment workbench upper table (3) is slidably mounted on the reverse adjustment workbench middle table (4), the sliding direction of the reverse adjustment workbench middle table (4) on the reverse adjustment workbench lower table (5) is perpendicular to the sliding direction of the reverse adjustment workbench upper table (3) on the reverse adjustment workbench middle table (4), and the workpiece posture adjustment workbench is rotatably mounted on the reverse adjustment workbench upper table (3).
4. A dynamically adjustable seven-axis table capable of eliminating curved surface machining nonlinear errors according to claim 1, wherein the workpiece posture adjustment table comprises a workpiece posture adjustment table lower table (2) and a workpiece posture adjustment table upper table (1);
the workpiece posture adjustment workbench comprises a workpiece posture adjustment workbench, and is characterized in that an upwards extending mounting frame is arranged on the reverse adjustment workbench, a workpiece posture adjustment workbench lower table (2) is rotatably mounted in the mounting frame on the reverse adjustment workbench, a workpiece posture adjustment workbench upper table (1) is rotatably mounted on the workpiece posture adjustment workbench lower table (2), a rotating shaft of the reverse adjustment workbench lower table (5) is perpendicular to a rotating shaft of the workpiece posture adjustment workbench lower table (2), and the rotating shaft of the workpiece posture adjustment workbench lower table (2) is perpendicular to and intersected with the rotating shaft of the workpiece posture adjustment workbench upper table (1).
5. The dynamically adjustable seven-axis workbench capable of eliminating nonlinear errors in curved surface machining according to claim 4, wherein the rotating shaft of the counter-adjustment workbench is coaxial with the rotating shaft of the workpiece posture adjustment workbench (1) in the initial position.
6. The method of using a dynamically adjustable seven-axis table for eliminating non-linear errors in curved surface machining according to any one of claims 1-5, comprising the steps of:
1) Dispersing all tool path space curves in the workpiece space curved surface into a plurality of corresponding tool path plane curves respectively; determining a plurality of approximate arcs corresponding to the plane curves of the tool tracks, and further calculating circle centers and radiuses corresponding to the approximate arcs; determining an initial tool path space curve and a corresponding initial tool path plane curve;
2) Fixedly mounting a workpiece to be processed on a workpiece posture adjustment workbench, fixedly mounting a dynamic adjustable seven-axis workbench on a gantry five-axis linkage machine tool, recovering to an initial position, and adjusting the workpiece posture adjustment workbench to enable the plane of the plane curve of the current tool track to coincide with the processing plane of the dynamic adjustable seven-axis workbench;
3) According to the circle center position and the radius corresponding to each approximate circular arc, adjusting the circle center positioning workbench and the cutter of the gantry five-axis linkage machine tool, and through the rotary motion between the reverse adjustment workbench and the circle center positioning workbench, generating relative motion between the cutter and a workpiece to be processed, and processing a current approximate circular arc on the workpiece to be processed, wherein the cutter position point of the cutter is kept unchanged in the current processing process, and the cutter axis vector is kept unchanged, so that the processing of the current approximate circular arc is completed;
4) The reverse adjusting workbench is reversely adjusted according to the translational movement of the circle center positioning workbench, so that the position of a workpiece to be processed and the position of a cutter are not changed, and then the reverse adjusting workbench is driven to perform rotary movement on the circle center positioning workbench, so that the cutter position and the cutter shaft vector of the cutter are respectively and independently changed, and the cutter is enabled to work to the next cutter position;
5) Repeating 3) -4) processing the corresponding approximate arc and driving the cutter to work to the next cutter point according to the circle center and the radius of the next approximate arc in the current cutter path plane curve until all the approximate arcs in the current cutter path plane curve are processed in a traversing way;
6) The gesture of the workpiece to be processed is adjusted by adjusting the workpiece gesture adjusting workbench, so that the processing surface of the dynamic adjustable seven-axis workbench coincides with the plane of the plane curve of the next tool path, and then the tool bit point is moved to the position of the first tool bit point of the plane curve of the current tool path;
7) Repeating 3) -6), processing the corresponding tool path plane curve according to the circle centers and the radiuses of all approximate arcs of the rest tool path plane curves in the current tool path space curve until the current tool path space curve is processed;
8) And 7) traversing the space curve of the rest tool path of the machining until the machining obtains an actual space curved surface, thereby obtaining the target workpiece.
7. The method of claim 6, wherein each tool path space curve in the workpiece space curve is discretized into a plurality of tool path plane curves by:
each tool path space curve consists of a plurality of discrete tool position points, whether adjacent tool position points are located on the same plane or not is judged in sequence, and turning points between the two adjacent planes are determined, so that each plane is determined, and each tool path plane curve is formed by the tool position points in each plane.
8. The method for using a dynamically adjustable seven-axis worktable capable of eliminating nonlinear errors in curved surface machining according to claim 6, wherein in the 4), the reverse adjustment worktable is driven to perform rotary motion on the center positioning worktable, and the knife point and the knife axis vector of the knife are respectively and independently changed, so that the knife works to the next knife point, specifically:
the cutter shaft vector of the cutter at the position of the last cutter position is unchanged, the reverse adjusting workbench is driven to perform rotary motion on the circle center positioning workbench, so that the cutter moves to the position of the next cutter position, and then the cutter shaft vector of the cutter position of the cutter is changed on the premise that the position of the next cutter position is unchanged; or on the premise that the position of the last cutter position point is unchanged, the cutter shaft vector of the cutter position point of the cutter is changed, and then on the premise that the cutter shaft vector is kept unchanged, the reverse adjusting workbench is driven to perform rotary motion on the circle center positioning workbench, so that the cutter moves to the position of the next cutter position point.
9. The method for using a dynamically adjustable seven-axis workbench capable of eliminating non-linear errors in curved surface machining according to claim 6, wherein the workpiece to be machined in 2) is a workpiece which is roughly machined by a gantry five-axis linkage machine tool.
10. The method of using a dynamically adjustable seven-axis table capable of eliminating non-linear errors in curved surface machining according to claim 6, wherein in 3), the position of the center positioning table axis is adjusted according to the center position corresponding to each approximate circular arc, so that the axis of the center positioning table coincides with the center of the approximate circular arc, the position of the tool bit point of the gantry five-axis linkage machine tool is adjusted according to the radius corresponding to each approximate circular arc, so that the position of the tool bit point is on the arc of the approximate circular arc, and the tool and the workpiece to be machined generate relative motion and machine the current approximate circular arc on the workpiece to be machined by reversely adjusting the rotary motion between the table and the center positioning table.
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| CN202310858810.XA CN116619060A (en) | 2023-07-13 | 2023-07-13 | Dynamically adjustable seven-axis workbench and method capable of eliminating nonlinear errors of curved surface machining |
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| CN202310858810.XA CN116619060A (en) | 2023-07-13 | 2023-07-13 | Dynamically adjustable seven-axis workbench and method capable of eliminating nonlinear errors of curved surface machining |
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