Optical Machining Numerical Control Program Generation Method for Oblique Axis Numerical Control Machine Tools

Abstract

The present invention relates to the field of optical processing technology, and particularly to a method for generating a numerical control program for optical processing of an inclined-axis numerical control machine tool. According to the position axis coordinate system and the attitude rotation axis coordinate system of the inclined-axis numerical control machine tool, a tool coordinate system of a processing tool on the inclined-axis numerical control machine tool is established; according to the surface shape and processing technology of the optical element to be processed, the surface shape residual error and the removal function distribution of the optical element are obtained; the processing trajectory of the optical element is determined, and in combination with the surface shape residual error and the removal function distribution, the ideal dwell point and dwell time for processing the optical element are determined; according to the tool coordinate system and the attitude axis coordinate system of the inclined-axis numerical control machine tool, as well as the surface shape, the attitude of the processing tool during processing is determined; according to the attitude, the ideal dwell point and the dwell time, the processing program of the optical element to be processed is determined. The present invention standardizes the process of the difficult problem of generating the numerical control program of the inclined-axis numerical control machine tool, and has good practicality in code generation.

Description

Technical Field

[0001] The present invention belongs to the technical field of optical processing, and particularly relates to a method for generating a numerical control program for optical processing of an inclined-axis numerical control machine tool. Background Art

[0002] Existing machine tools mostly adopt a standard axis configuration, such as the position axes XYZ and the attitude axes ABC that rotate around XYZ. Such an axis configuration is relatively simple to program in optical processing applications, and the technology is already very mature. If the workpiece to be processed is a curved surface with a very high slope, there will be mechanical interference phenomena when the standard machine tool with a standard axis system processes it. To avoid mechanical interference phenomena, there are also some applications of inclined-bed numerical control machine tools on the market. The plane where the guide rail is located intersects with the ground plane to form an inclined plane, which can effectively utilize space, greatly reduce the floor area of the machine tool on the plane, facilitate chip removal, and can arrange more tool positions, and it has played a good role in the production of complex parts. For large-aperture optical elements, the support structure of the inclined-bed object platform poses a huge challenge to the optical elements. In order to utilize the characteristics of the inclined platform, an inclined-axis numerical control machine tool is used to handle the polishing task of large-aperture optical elements. Its characteristic is that the object platform is horizontal and the tool is inclined, so one or several attitude axes need to be offset to make it have a greater tool freedom. However, for an inclined-axis numerical control machine tool, the difficulty of writing machining codes has increased significantly because key issues such as coordinate changes need to be considered. Summary of the Invention

[0003] In view of this, the present invention aims to provide a method for generating a numerical control program for optical processing of an inclined-axis numerical control machine tool, to determine the surface shape of an optical element, determine the ideal dwell point position during polishing, calculate the dwell time corresponding to the ideal dwell point; calculate the attitude of the polishing dwell point, and generate a numerical control machine tool file executed by the inclined-axis numerical control machine tool.

[0004] To achieve the above object, the technical solution of the present invention is realized as follows:

[0005] A method for generating a numerical control program for optical processing of an inclined-axis numerical control machine tool, comprising:

[0006] S1: Establish a tool coordinate system of the processing tool on the inclined-axis numerical control machine tool according to the position axis coordinate system and the attitude rotation axis coordinate system of the inclined-axis numerical control machine tool;

[0007] S2: Obtain the surface shape residual and the removal function distribution of the optical element according to the surface shape and processing technology of the optical element to be processed;

[0008] S3: Determine the processing trajectory of the optical element, and combine the surface shape residual and the removal function distribution obtained in step S2 to determine the ideal dwell point and dwell time for processing the optical element;

[0009] S4: Determine the posture of the machining tool during machining based on the tool coordinate system of step S1, the posture axis coordinate system of the oblique axis CNC machine tool, and the surface shape;

[0010] S5: Determine a processing program for processing the optical element based on the posture obtained in step S4 and the ideal dwell point and dwell time obtained in step S3.

[0011] Furthermore, in step S1 , the origin of the attitude rotation axis coordinate system coincides with the origin of the tool coordinate system, and the coordinate axis direction of the tool coordinate system is the same as the coordinate axis direction of the position axis coordinate system.

[0012] Furthermore, in step S3: the ideal dwell point is determined according to the machining trajectory and the surface shape; and the dwell time is calculated by the following formula:

[0013] ;

[0014] Among them, e i =E(x i ,y i ,z i ), r ij =R j (x i -ε j ,y i -η j ,z i -γ j ), t j =T(ε j ,η j ,γ j ), E(x i ,y i ,z i ) represents the i-th surface point (x i ,y i ,z i ), 1≤i≤I, I represents the surface point (x i ,y i ,z i ), R j (x i -ε j ,y i -η j ,z i -γ j ) indicates that the removal function is distributed at the jth ideal residence point (ε j ,η j ,γ j ) at the removal function distribution, T(ε j ,η j ,γ j ) represents the jth ideal dwelling point (εj , η j , γ j ), the residence time, 1 ≤ j ≤ J, where J represents the ideal residence points (ε j , η j , γ j ) of the total number.

[0015] Further, in step S4: Obtain the coordinate transformation operator between the tool coordinate system and the attitude axis coordinate system; Calculate the marked points on the ideal tool scope of the machining tool where the surface normal of the surface is consistent with the surface normal of the surface shape; Transform the marked points into attitudes through the coordinate transformation operator.

[0016] Further, in step S5: The ideal residence points are the positions of the machining points in the machining program; The attitude is the attitude of the machining tool at the corresponding machining point described in the machining program during machining; Calculate the displacement between two ideal residence points, and obtain the machining feed rate in the machining program according to the displacement and the residence time.

[0017] Further, the position of the machining point is the coordinate of the machining point in the position axis coordinate system, the attitude is the coordinate of the machining tool in the attitude axis coordinate system, and the machining feed rate is the feed rate of the machining tool in the position axis coordinate system.

[0018] Compared with the prior art, the present invention can achieve the following beneficial effects:

[0019] The method for generating an optical machining numerical control program for an inclined axis numerically controlled machine tool according to the present invention can be applied to the polishing of complex curved surfaces in ultra-precision polishing, consider the code generation process of any inclined axis numerically controlled machine tool, and has a relatively high reliability of the code generation strategy. The proposal of the present invention solves the problem of machine tool code generation for inclined axis numerically controlled machine tools. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] The accompanying drawings forming a part of the present invention are used to provide a further understanding of the present invention. The schematic embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation to the present invention. In the drawings:

[0021] Figure 1 is a schematic flow chart of the method for generating an optical machining numerical control program for an inclined axis numerically controlled machine tool according to an embodiment of the present invention;

[0022] Figure 2 is a schematic diagram of the relative position relationship between the position axis coordinate system and the attitude rotation axis coordinate system according to an embodiment of the present invention;

[0023] Figure 3 is a schematic diagram of the position relationship between the attitude rotation axis coordinate system and the end position of the machining tool according to an embodiment of the present invention;

[0024] Figure 4 Schematic diagram of the positional relationship between the tool coordinate system and the attitude rotation axis coordinate system according to the embodiment of the present invention

[0025] Figure 5 Schematic diagram of the relationship between the attitude rotation axis coordinate system and the attitude axis coordinate system of the non-standard five-axis machine tool according to the embodiment of the present invention

[0026] Figure 6 Schematic diagram of the configuration of the attitude rotation axis in the non-standard five-axis machine tool according to the embodiment of the present invention

[0027] Figure 7 Surface residual error diagram according to the embodiment of the present invention

[0028] Figure 8 Removal function distribution diagram according to the embodiment of the present invention

[0029] Figure 9 Dwell time distribution diagram according to the embodiment of the present invention

[0030] Figure 10 Example diagram of a part of the machining program according to the embodiment of the present invention Detailed implementation manners

[0031] In order to make the objectives, technical solutions and advantages of the present invention more clear and understandable, the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and do not constitute a limitation to the present invention.

[0032] It should be noted that, without conflict, the embodiments in the present invention and the features in the embodiments may be combined with each other.

[0033] In the description of the present invention, it should be understood that the orientation or positional relationship indicated by the terms "center", "longitudinal", "transverse", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc. is based on the orientation or positional relationship shown in the drawings, and is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be construed as a limitation on the present invention. In addition, the terms "first", "second", etc. are only used for descriptive purposes and cannot be understood as indicating or implying relative importance or implicitly specifying the quantity of the indicated technical features. Thus, the features defined with "first", "second", etc. may explicitly or implicitly include one or more of such features. In the description of the present invention, unless otherwise specified, the meaning of "a plurality" is two or more.

[0034] In the description of the present invention, it should be noted that unless otherwise clearly defined and limited, the terms "installed", "connected", "coupled" shall be understood in a broad sense. For example, it may be a fixed connection, a detachable connection, or an integral connection; it may be a mechanical connection or an electrical connection; it may be directly connected or indirectly connected through an intermediate medium, and it may be the communication inside two elements. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood through specific circumstances.

[0035] The present invention will be described in detail below with reference to the drawings and in conjunction with embodiments.

[0036] As Figures 1 to 4 shown, the method for generating an optical machining numerical control program for an inclined-axis numerically controlled machine tool according to an embodiment of the present invention includes:

[0037] S1: Establish a tool coordinate system for the machining tool on the inclined-axis numerically controlled machine tool according to the position axis coordinate system and the attitude rotation axis coordinate system of the inclined-axis numerically controlled machine tool.

[0038] In some embodiments, the origin of the attitude rotation axis coordinate system coincides with the origin of the tool coordinate system, and the axis directions of the tool coordinate system are the same as those of the position axis coordinate system.

[0039] The attitude axis in the inclined axis CNC machine tool usually has a rotational function, specifically, the attitude axis rotates around the attitude rotation axis where the attitude axis is located; for the non-standard six-axis machine tool in the inclined axis CNC machine tool, the attitude axis coordinate system of its non-standard attitude axis is defined as UWV, and correspondingly, the attitude of the processing tool during processing is expressed as (U, W, V); for the non-standard five-axis machine tool in the inclined axis CNC machine tool, the attitude axis coordinate system of its non-standard attitude axis is defined as WV, and correspondingly, the attitude of the processing tool during processing is expressed as (W, V). In a certain embodiment, the position axis coordinate system of the inclined axis CNC machine tool is defined as XYZ, such as Figure 2 As shown in (a); the posture rotation axis coordinate system of the inclined axis CNC machine tool is defined as X r Y r Z r ,like Figure 2 As shown in (b), taking a non-standard six-axis machine tool as an example, during the machining process, the U-posture axis, W-posture axis, and V-posture axis in the posture axis coordinate system correspond to the X-posture axis in the posture rotation axis coordinate system. r Axis, Y r Axis and Z r Axis rotation; attitude rotation axis coordinate system X r Y r Z r The relative position relationship of the coordinate axis of the position axis coordinate system XYZ is as follows Figure 2 The positional relationship between the attitude rotation axis coordinate system and the end position (Pos) of the processing tool is shown as follows: Figure 3 As shown, Figure 2 (b) and Figure 3 The α in the figure represents the Z axis in the position axis coordinate system where the end position of the processing tool is located, and the X axis in the posture rotation axis coordinate system where the end position of the processing tool is located is different from the Z axis in the position axis coordinate system where the end position of the processing tool is located. r Y r Z r Z in r The angle between the axes. The tool coordinate system of the machining tool is defined as X'Y'Z'. Specifically, Figure 4 As shown, the attitude rotation axis coordinate system X r Y r Z r Origin O r The origin O of the tool coordinate system X'Y'Z' T Coincidentally, the coordinate axis direction of the tool coordinate system X'Y'Z' is the same as the coordinate axis direction of the position axis coordinate system XYZ.

[0040] S2: According to the surface shape and processing technology of the optical element to be processed, the surface shape residual and removal function distribution of the optical element are obtained.

[0041] In some embodiments, the surface shape of an optical element is measured using an interferometer to obtain the surface shape residual of the optical element. A removal function distribution is determined based on the machining process of the workpiece to be machined. The present invention is not limited to a single process and can also be used in other deterministic polishing processes such as ion beam shaping and airbag polishing.

[0042] S3: Determine the processing trajectory of the optical element, and combine the surface residual and removal function distribution obtained in step S2 to determine the ideal dwell point and dwell time for processing the optical element.

[0043] In some embodiments, an ideal dwell point is determined based on the machining trajectory and the surface shape.

[0044] The dwell time is calculated by the following formula:

[0045] ;

[0046] Among them, e i =E(x i ,y i ,z i ), r ij =R j (x i -ε j ,y i -η j ,z i -γ j ), t j =T(ε j ,η j ,γ j ), E(x i ,y i ,z i ) represents the i-th surface point (x i ,y i ,z i ), 1≤i≤I, I represents the surface point (x i ,y i ,z i ), R j (x i -ε j ,y i -η j ,z i -γ j ) indicates that the removal function is distributed at the jth ideal residence point (ε j ,η j ,γ j ) at the removal function distribution, T(ε j ,η j ,γ j ) represents the jth ideal dwelling point (ε j ,ηj , γ j ), the residence time, 1 ≤ j ≤ J, where J represents the ideal residence points (ε j , η j , γ j ).

[0047] S4: Determine the posture of the machining tool during machining based on the tool coordinate system in step S1, the posture axis coordinate system of the inclined-axis numerically controlled machine tool, and the surface shape of the optical element.

[0048] In some embodiments, step S4 includes: obtaining the coordinate transformation operator between the tool coordinate system and the posture axis coordinate system; calculating the marked points where the surface normal on the ideal tool scope of the machining tool is consistent with the surface normal of the surface shape; transforming the marked points into postures through the coordinate transformation operator.

[0049] S5: Determine the machining program for machining the optical element based on the posture obtained in step S4 and the ideal residence points and residence times obtained in step S3.

[0050] In some embodiments, step S5 includes: the ideal residence points are the positions of the machining points in the machining program; the posture is the posture of the machining tool at the corresponding machining points described in the machining program; calculating the displacement between two ideal residence points, and obtaining the machining feed rate in the machining program based on the displacement and the residence time. Wherein, the position of the machining point is the coordinate of the machining point in the position axis coordinate system, the posture is the coordinate of the machining tool in the posture axis coordinate system, and the machining feed rate is the feed rate of the machining tool in the position axis coordinate system.

[0051] In a certain embodiment, serialize the ideal residence points, postures, and residence times, and obtain the machining point coordinates, displacements, and feed rates through the following loop statements:

[0052] For non-standard six-axis machine tools in inclined-axis numerically controlled machine tools, there is:

[0053] ;

[0054] For non-standard five-axis machine tools in inclined-axis numerically controlled machine tools, there is:

[0055] .

[0056] Among them, k represents the k-th ideal stationary point after discretization, (X, Y, Z) represents the coordinates of the machining point in the position axis coordinate system, that is, the position coordinates of the k-th ideal stationary point, and (U, W, V) or (W, V) represents the coordinates of the machining tool in the attitude axis coordinate system, that is, the attitude coordinates of the machining tool at the k-th ideal stationary point. F represents the feed rate, which is the ratio of the displacement S(k) between the k-th ideal stationary point and the (k + 1)-th ideal stationary point to the dwell time of the k-th ideal stationary point. It should be noted that since the axis directions of the tool coordinate system are the same as those of the position axis coordinate system, from the formula of the feed rate F, it can be obtained that the feed rate of the machining tool in the position axis coordinate system is actually equivalent to the feed rate of the machining tool in the tool coordinate system.

[0057] The optical machining numerical control program generation method for the inclined axis type numerical control machine tool described in the embodiment of the present invention is applicable to the inclined axis type numerical control machine tool, that is, all attitude axes are composed of non-standard attitude axes; it is also applicable to some non-standard axis system machine tools, that is, the attitude axes are composed of non-standard attitude axes and standard attitude axes. To clearly illustrate the optical machining numerical control program generation method for the inclined axis type numerical control machine tool described in the embodiment of the present invention, an embodiment of the optical machining numerical control program generation method for a five-axis machine tool with a partial non-standard axis system is provided. The method provided in this embodiment includes:

[0058] S1: Establish a tool coordinate system for the machining tool on the inclined axis type numerical control machine tool according to the position axis coordinate system and the attitude rotation axis coordinate system of the inclined axis type numerical control machine tool.

[0059] In this embodiment, it is to establish a tool coordinate system for the machining tool on the five-axis numerical control machine tool with a partial non-standard axis system according to the position axis coordinate system and the attitude rotation axis coordinate system of the five-axis numerical control machine tool with a partial non-standard axis system.

[0060] Specifically, the attitude axes of the five-axis numerical control machine tool with a partial non-standard axis system are defined as BV, that is, one axis is a standard attitude axis rotating around Y, and one axis is a non-standard attitude axis V. Its attitude rotation axis coordinate system is defined as X r Y r Z r , and the relationship between the attitude rotation axis coordinate system X r Y r Z r of the five-axis numerical control machine tool with a partial non-standard axis system and the attitude axis coordinate system BV is as Figure 5 shown. The origin O r Y r Z r of the attitude rotation axis coordinate system X r is the origin O T of the tool coordinate system X’Y’Z’.Coincide, and the axis directions of the tool coordinate system X'Y'Z' are the same as those of the position axis coordinate system XYZ. The configuration of the attitude rotation axis in the five-axis CNC machine tool provided in this embodiment is as Figure 6 shown, where PoleB represents the length of the B-axis rotating rod in the five-axis CNC machine tool with a partially non-standard axis system.

[0061] S2: According to the surface shape and processing technology of the optical element to be processed, obtain the surface shape residual and removal function distribution of the optical element.

[0062] In this embodiment, the surface shape of the optical element is measured by an interferometer to obtain the surface shape residual of the optical element as shown in Figure 7 shown. The processing technology selects small grinding head polishing, and its removal function distribution is as shown in Figure 8 shown.

[0063] The surface equation of the optical element to be processed is:

[0064] ;

[0065] where (x, y, z) represents the surface height coordinates of the optical element.

[0066] S3: Determine the processing trajectory of the optical element, and combine the surface shape residual and removal function distribution obtained in step S2 to determine the ideal dwell point and dwell time for processing the optical element.

[0067] In this embodiment, the ideal dwell point coincides with the surface shape point. The dwell time is calculated by the following formula:

[0068] ;

[0069] to obtain the dwell time as shown in Figure 9 shown.

[0070] S4: According to the tool coordinate system and attitude axis coordinate system in step S1, and the surface shape, determine the attitude of the processing tool during processing.

[0071] In this embodiment, step S4 includes:

[0072] Obtain the coordinate transformation operator Trans between the tool coordinate system and the attitude axis coordinate system, that is:

[0073] ;

[0074] where represents the composition of operations, which are executed sequentially from right to left. That is, this transformation first rotates by α° around the Y r axis, then reverses the Y r axis, and then the X rThe axis is reversed, and finally the spherical coordinates corresponding to the current Cartesian coordinates are obtained.

[0075] Calculate the marked points where the surface normal on the ideal tool action range of the processing tool is consistent with the surface normal of the surface shape, that is:

[0076] Through the surface equation z = f(x, y) of the optical element, the surface normal of the optical element is obtained as:

[0077] ;

[0078] Among them, represents the surface normal of the optical element. The marked points are obtained through the following formula:

[0079] ;

[0080] Among them, P I represents the marked point, and p represents the calculation parameter of the action point of the processing tool on the B-axis rotating rod, which is:

[0081] ; [[ID=3--]]

[0082] The marked points are transformed into postures through the coordinate transformation operator, that is:

[0083] . [[ID=--6]]

[0084] S5: Determine the processing program for machining the optical element according to the posture obtained in step S4 and the ideal dwell point and dwell time obtained in step S3. [[ID=--9]]

[0085] In this embodiment, the ideal dwell point, posture, and dwell time are serialized, and the position, posture, displacement, and feed speed of the processing points are obtained through the following loop statement:

[0086] .

[0087] After obtaining the position (X, Y, Z) of the processing point, the posture (B, V) of the processing point, and the feed speed F, a partial processing program as shown in Figure 10 is obtained.

[0088] It should be understood that various forms of the flow shown above can be used, reordering, adding, or deleting steps. For example, the steps recorded in the disclosure of the present invention can be executed in parallel, sequentially, or in a different order, as long as the desired results of the technical solution disclosed in the present invention can be achieved, and no limitations are made herein.

[0089] The above specific embodiments do not constitute a limitation on the protection scope of the present invention. Those skilled in the art should understand that various modifications, combinations, sub - combinations and substitutions can be made according to design requirements and other factors. Any modifications, equivalent substitutions and improvements made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims

1. A method for generating a numerical control program for optical machining of an inclined axis numerical control machine tool, characterized in that, Including: S1: Establish a tool coordinate system of a machining tool on the bevel-axis numerically controlled machine tool according to the position axis coordinate system and the attitude rotation axis coordinate system of the bevel-axis numerically controlled machine tool; S2: Obtain the surface form residual and the removal function distribution of the optical element according to the surface form and the machining process of the optical element to be machined; S3: Determine the machining trajectory of the optical element, and combine the surface form residual and the removal function distribution obtained in step S2 to determine the ideal dwell point and the dwell time for machining the optical element; S4: Determine the attitude of the machining tool during machining according to the tool coordinate system in step S1, the attitude axis coordinate system of the bevel-axis numerically controlled machine tool, and the surface form; S5: Determine the machining program for machining the optical element according to the attitude obtained in step S4, and the ideal dwell point and the dwell time obtained in step S3.

2. The optical machining numerical control program generation method for the inclined-axis numerically controlled machine tool according to claim 1, characterized in that, In step S1, the origin of the attitude rotation axis coordinate system coincides with the origin of the tool coordinate system, and the axis directions of the tool coordinate system are the same as those of the position axis coordinate system.

3. The optical machining numerical control program generation method for the skew-axis numerically controlled machine tool according to claim 1, characterized in that In step S3: Determine the ideal dwell point according to the machining trajectory and the surface form; Calculate the dwell time by the following formula: ； Among them, e i = E(x i , y i , z i ), r ij = R j (x i - ε j , y i - η j , z i - γ j ), t j = T(ε j , η j , γ j ), E(x i , y i , z i ) represents the surface form residual of the i-th surface form point (x i , y i , z i ), where 1 ≤ i ≤ I, and I represents the total number of the surface form points (x i , y i , z i ). R j (x i - ε j , y i - η j , z i - γ j ) represents the removal function distribution at the j-th ideal dwell point (ε j , η j , γ j ). T(ε j , η j , γ j ) represents the dwell time at the j-th ideal dwell point (ε j , η j , γ j ), where 1 ≤ j ≤ J, and J represents the total number of the ideal dwell points (ε j , η j , γ j ).

4. The optical machining numerical control program generation method for the skew-axis numerically controlled machine tool according to claim 1, wherein In step S4: Obtain the coordinate transformation operator between the tool coordinate system and the attitude axis coordinate system; Calculate the marked points where the surface normal on the ideal tool working range of the machining tool is consistent with the surface normal of the surface form; Convert the marked points into the attitude through the coordinate transformation operator.

5. The optical machining numerical control program generation method for the skew-axis numerically controlled machine tool according to claim 1, characterized in that, In step S5: The ideal dwell point is the position of the machining point in the machining program; The attitude is the attitude of the machining tool at the corresponding machining point described in the machining program during machining; Calculate the displacement between two ideal dwell points, and obtain the machining feed rate in the machining program according to the displacement and the dwell time.

6. The optical machining numerical control program generation method for the skew-axis numerically controlled machine tool according to claim 5, wherein, The position of the machining point is the coordinate of the machining point in the position axis coordinate system, the attitude is the coordinate of the machining tool in the attitude axis coordinate system, and the machining feed rate is the feed rate of the machining tool in the position axis coordinate system.

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