Flexible dressing method for grinding wheel with complex surface

Abstract

The invention discloses a flexible dressing method for a grinding wheel with a complex profile, which comprises the following steps: S1, acquiring a grinding wheel profile, and acquiring a continuous fine dressing curve by adopting an equidistant line method according to the grinding wheel profile; s2, extracting entity segment data information of the continuous fine finishing curve to obtain fine finishing track information; s3, presetting a theoretical single cutting depth, discretizing the continuous fine finishing curve to obtain fine finishing discrete points, and creating a fine finishing discrete track according to the fine finishing discrete points; s4, constructing a profiling allowance distribution model; comprising the steps that a rough finishing boundary and a tool retracting position boundary are established based on fine finishing discrete points according to preset profiling allowance, and a rough finishing track is established according to the rough finishing boundary and the tool retracting position boundary; and S5, the grinding wheel is trimmed according to the rough trimming discrete track and the fine trimming discrete track in sequence. According to the method, the continuous fine dressing curve is automatically dispersed, and the dressing path under the condition of profiling allowance is designed, so that the grinding wheel dressing flexibility degree and the dressing accuracy and universality are improved.

Description

Technical Field

[0001] The invention belongs to the field of grinding wheel manufacturing and grinding processing applications, and mainly relates to a flexible dressing method for grinding wheels with complex surfaces. Background Art

[0002] As modern manufacturing develops towards high precision, high efficiency and complexity, ordinary shaped grinding wheels are limited by standard geometric shapes and are difficult to meet the processing requirements of complex contours, fine structures and special functional surfaces. Complex shaped grinding wheels (such as special-shaped contours, curved surfaces, tooth shapes, spiral grooves, etc.) have come into being. Complex shaped precision parts such as engine crankshaft flanges, aviation blade tenons, bearing grooves, gears, spiral worms, etc. usually require the use of complex shaped grinding wheels for grinding. First, the grinding wheel is trimmed into a specific shape, and then the forming grinding process is performed. This is a common processing method for the above-mentioned high-precision workpieces. Since most high-precision workpieces are customized products and the shapes of different workpieces vary greatly, the currently used forming roller copy dressing method has become a process and technical problem that restricts the application of grinding wheels in the grinding of complex shaped workpieces due to its high process cost, poor versatility and uncontrollable grinding wheel dressing accuracy.

[0003] Therefore, it is necessary to solve the problems of difficult dressing of complex-shaped grinding wheel surfaces and the inability to control precision. It is urgent to develop a method with strong versatility and high flexibility to achieve precise dressing of grinding wheels of different shapes. Summary of the Invention

[0004] The purpose of the present invention is to overcome the shortcomings of the above-mentioned prior art, improve the versatility and flexibility of grinding wheel dressing, and provide a flexible dressing method for grinding wheels with complex surfaces.

[0005] In order to achieve the above object, the present invention adopts the following technical solutions:

[0006] A flexible dressing method for a complex-surface grinding wheel comprises the following steps:

[0007] S1: obtaining a sand profile diagram, and obtaining a continuous fine-tuning curve according to the sand profile diagram using an equidistant line method, wherein the continuous fine-tuning curve includes straight line segments and / or circular arc segments;

[0008] S2: extracting entity segment data information of the continuous fine-tuning curve to obtain fine-tuning trajectory information, wherein the fine-tuning trajectory information includes curve type, number of curve segments, and curve position. The curve type includes straight line segments and circular arc segments. The curve position of the straight line segment includes the starting point coordinates and the end point coordinates of each straight line segment. The curve position of the circular arc segment includes the center coordinates, radius value, starting angle, and ending angle of each circular arc segment.

[0009] S3: Preset a theoretical single cutting depth, discretize the continuous fine-tuning curve according to the theoretical single cutting depth and fine-tuning trajectory information to obtain fine-tuning discrete points, and create a fine-tuning discrete trajectory according to the fine-tuning discrete points, wherein the fine-tuning discrete points include straight line segment discrete points and / or arc segment discrete points, and each straight line segment discrete point is obtained by performing layered discretization on the straight line segment according to the theoretical single cutting depth of each straight line segment, and each arc segment discrete point is obtained by performing equal-angle discretization on the arc segment according to the theoretical single cutting depth of each arc segment;

[0010] S4: constructing a profiling allowance distribution model; including: establishing a rough trimming boundary and a tool retraction position boundary based on the fine trimming discrete points according to the preset profiling allowance, obtaining a profiling allowance distribution model composed of the rough trimming boundary and the tool retraction position boundary, and creating a rough trimming trajectory according to the rough trimming boundary and the tool retraction position boundary;

[0011] S5: Firstly, the grinding wheel is roughly dressed according to the rough dressing trajectory, and then the grinding wheel is finely dressed according to the fine dressing discrete trajectory.

[0012] Preferably, the equidistant line method in step S1 is: draw the normal outer equidistant line of the sand profile curve in the sand profile diagram to obtain the continuous finishing curve of the grinding wheel, and the equidistant distance of the normal outer equidistant line is the radius of the tool tip arc r d ;

[0013] In step S2, the dxflib library function is used to extract the entity segment data information of the continuous fine-tuning curve.

[0014] Preferably, the step S2 further includes the following steps: obtaining the number of curve segments of the straight line segment as n1, storing the data information of the curve position of the straight line segment in a matrix form in a first matrix L l ,but:

[0015]

[0016] Among them, [x1, y1] is the coordinate of the starting point of the first straight line segment, and [x1′, y1′] is the coordinate of the end point of the first straight line segment; is the coordinate of the starting point of the n1th straight line segment, is the coordinate of the end point of the n1th straight line segment, [] is an empty matrix;

[0017] Obtain the number of curve segments n2 of the arc segment, and store the curve position data information of the arc segment in the second matrix L in matrix form. c ,but:

[0018]

[0019] Where [xc1, yc1] is the coordinate of the center of the first arc segment, [r1] is the radius of the first arc segment; α1 and α1′ are the starting angle and ending angle of the first arc segment respectively; is the coordinate of the center of the n2th arc segment, is the radius of the n2th arc segment; They are the starting angle and ending angle of the n2th arc segment respectively.

[0020] Preferably, the step S3 is specifically as follows:

[0021] S3.1: Set the theoretical single cutting depth of the straight line segment to sp, and set the theoretical single cutting depth of the arc segment to sp′;

[0022] S3.2: Obtain the number of discrete points for each straight line segment based on the theoretical single cutting depth of the straight line segment and the coordinates of the starting point and the ending point of each straight line segment. Obtain the number of discrete points for each arc segment based on the theoretical single cutting depth of the circular arc segment and the coordinates of the center point, radius, starting angle, and ending angle of each arc segment.

[0023] S3.3: Discretize the straight line segments in layers according to the number of discrete points of the straight line segments to obtain the coordinates of the discrete points of the straight line segments; discretize the arc segments in equal angles according to the number of discrete points of the arc segments to obtain the coordinates of the discrete points of the arc segments;

[0024] S3.4: Combine the coordinates of the discrete points of the straight line segment and the discrete points of the arc segment, and use the sorting function to sort the Y-axis coordinate values ​​of the combined discrete points in descending order to obtain a set of discrete points, i.e., the refined discrete points P. m (xp m ,yp m ); m = 1, 2, 3, ..., N, where N is the total number of discrete points of straight line segments and circular arc segments;

[0025] S3.5: Create a fine-finishing discrete trajectory based on the fine-finishing discrete points. The fine-finishing discrete trajectory is the movement of the tool tip center from top to bottom according to the coordinates of the fine-finishing discrete points P1 to P N trajectory.

[0026] Preferably, the number of discrete points of each straight line segment is obtained according to the theoretical single cutting depth of the straight line segment and the coordinates of the starting point and the end point of each straight line segment in step S3.2, specifically:

[0027] Get the number of discrete points Nl of the straight line segment according to the curve position of the straight line segment i .

[0028] If |y i ′-y i |≤sp, then the starting point of the i-th straight line segment (xi ,y i ) and the end point (x i ′,y i ′) as discrete points, the number of discrete points:

[0029] Nl i =2;

[0030] Among them, i is the index of the number of straight line segments n1, y i and y i ′ are the ordinates of the starting and ending points of the i-th straight line segment respectively; if |y i ′-y i |>sp, then the number of discrete points:

[0031]

[0032] Where ceil is the rounding up function.

[0033] Preferably, the step S3.2 further includes: correcting the theoretical single cutting depth sp of the straight line segment to obtain the actual single cutting depth ap i , whose expression is:

[0034]

[0035] Preferably, the step S3.3 of discretizing the straight line segments in layers according to the number of discrete points of the straight line segments to obtain the coordinates of the discrete points of the straight line segments is specifically as follows:

[0036] Use the interval equal division function to divide the Y axis interval of the straight line segment [y i ′,y i ] Generate Nl with equal spacing within the range i values, get the array My i , whose expression is:

[0037] My i =linspace(y i ′,y i ,Nl i );

[0038] Among them, the linspace function is an interval equal division function;

[0039] Use the interpolation function at the starting point of the straight line segment (x i ,y i ) and the end point (x i ′,y i ′) with array My i Nl in i The linear interpolation is performed on the values ​​to obtain Nl after linear interpolation. iAn array Mx of corresponding horizontal coordinate values i , whose expression is:

[0040] Mx i =interp1([y i ,y i ′],[x i ,x i ′],My i ,′linear′);

[0041] Among them, interp1 is the interpolation function, and 'linear' is the linear interpolation method;

[0042] Using [Mx i ,My i ] represents the coordinates of discrete points of a straight line segment.

[0043] Preferably, the number of discrete points of each arc segment is obtained according to the theoretical single cutting depth of the arc segment and the center coordinates, radius value, starting angle and ending angle of each arc segment in step S3.2, specifically:

[0044] The coordinates of the starting point and the end point of each arc segment are calculated according to the coordinate expression of the arc segment. The coordinate expression of the arc segment is:

[0045]

[0046]

[0047] Among them, [xc j ,yc j ] is the coordinate of the center of the jth arc segment, r j is the radius of the jth arc segment; α j , α j ′ are the starting angle and ending angle of the jth arc segment, j is the index of the arc segment number n2, (xa j ,ya j ) is the coordinate of the starting point of the jth arc segment, (xa j ′,ya j ′) is the coordinate of the end point of the j-th arc segment;

[0048] And the end angle α j 'Perform angle correction to obtain the correction end angle α j ″, specifically:

[0049] When α j ′<α j When α j ″=α j ′+360°;

[0050] When α j ′>α j When α j ″=α j ';

[0051] Obtain the number of discrete points Nc according to the curve position of the arc segment j ,

[0052] If|ya j ′-ya j |≤sp′, then the starting point of the arc segment j (xa j ,ya j ) and the end point (xa j ′,ya j ′) as discrete points, the number of discrete points:

[0053] Nc j =2;

[0054] If|ya j ′-ya j |>sp′, then the number of discrete points:

[0055]

[0056] Where ceil is the rounding up function.

[0057] Preferably, in step S3.3, the arc segment is discretized at equal angles according to the number of discrete points of the arc segment to obtain the coordinates of the discrete points of the arc segment, specifically:

[0058] The angle interval [α j ,α j Generate Nc with equal spacing within the range of ″] j Angle values, get array Nα j , whose expression is:

[0059] Nα j =linspace(α j ,α j ″,Nc j );

[0060] According to the coordinate expression of the arc segment, the array Nα j Nc j Angle values ​​are calculated to obtain Nc j coordinate points, that is, the coordinates of the discrete points of the arc segment are obtained.

[0061] Preferably, the step S4 is specifically as follows:

[0062] S4.1: Establishing a rough trimming boundary and a tool retraction position boundary based on the fine trimming discrete points according to the preset profiling allowance to obtain a profiling allowance distribution model, including the following steps:

[0063] The profiling allowance includes the allowance value t1 and the rough trimming amount t2, and the fine trimming amount t3 = t1 - t2;

[0064] The retraction position boundary is established on an equidistant line that is spaced apart from the fine trimming discrete point by a margin value t1 in the X-axis direction.

[0065] A rough trimming boundary is established on an equidistant line that is spaced apart from the tool retraction position boundary by a rough trimming amount t2 in the X-axis direction.

[0066] Then the coordinate point P of the rough trimming boundary m ′(xp m ′,yp m ′) and the coordinate point P of the retraction position boundary m ″(xp m ″,yp m The expression of ″) is:

[0067]

[0068] S4.2: Establishing a rough trimming trajectory according to the rough trimming boundary and the tool retraction position boundary, wherein the rough trimming trajectory includes an initial rough trimming path and cyclic rough trimming path units.

[0069] The initial rough finishing path includes an initial rough cutting path and an initial tool retraction path. The initial rough cutting path is a path where the tool tip center moves from P1″ to P1′, and the initial tool retraction path is a path where the tool tip center moves from P1′ to P1″.

[0070] The rough finishing path unit includes a feed path, a unit rough cutting path and a unit retract path which are arranged in sequence. The feed path is a path from the tool tip center to the path of P. q Move to P q+1 ″path, the unit cutting path is the tool tip center by P q+1 Move to P q+1 'path, the unit retraction path is the tool tip center by P q+1 ' moves toward P q+1 ″ path, where q is 1, 2, ..., N-1.

[0071] The beneficial effects of the present invention are:

[0072] The present invention extracts the fine dressing trajectory information that forms the sand profile based on the two-dimensional electronic graphic file of the sand profile curve in combination with the shape parameters of the dressing tool; through the rational discretization of the continuous fine dressing curve, discrete point information data with controllable fitting accuracy is formed, and the rough dressing trajectory and fine dressing discrete trajectory of the grinding wheel are automatically generated according to the discrete point data, thereby dressing the grinding wheel.

[0073] The present invention can improve the discrete accuracy by reducing the theoretical single cutting depth and increasing the number of discrete points, thereby realizing the adjustment and control of the finishing accuracy.

[0074] Compared with traditional methods, it has a high degree of flexibility and is suitable for the precision dressing of various complex-shaped grinding wheels. BRIEF DESCRIPTION OF THE DRAWINGS

[0075] The present invention is described in further detail below with reference to the accompanying drawings:

[0076] Figure 1 is a block diagram of the method of the present invention;

[0077] Figure 2 Schematic diagram of a straight line segment continuous finishing curve and a straight line segment continuous finishing curve connected to each other;

[0078] Figure 3 Schematic diagram of the connection between the straight segment continuous finishing curve and the arc segment continuous finishing curve of the present invention;

[0079] Figure 4 Schematic diagram of the distribution of fine-trimming discrete points on the fine-trimming discrete trajectory of the present invention;

[0080] Figure 5 is a schematic diagram of the fine-tuning discrete trajectory of the present invention;

[0081] Figure 6 Schematic diagram of the profiling margin distribution model of the present invention;

[0082] Figure 7 is a schematic diagram of a rough trimming trajectory of the present invention;

[0083] Figure 8 It is a schematic diagram of the sand profile used in the practice of the present invention;

[0084] Figure 9 Schematic diagram of a continuous fine trimming curve when implementing the present invention;

[0085] Figure 10 Schematic diagram of the distribution of discrete points for fine-tuning during implementation of the present invention;

[0086] Figure 11 It is a simulation diagram of the refined discrete trajectory when the present invention is implemented;

[0087] Figure 12 It is a simulation diagram of the rough trimming trajectory when the present invention is implemented. DETAILED DESCRIPTION

[0088] like Figure 1 As shown, the present invention provides a flexible dressing method for a complex-surface grinding wheel, comprising the following steps:

[0089] S1: Obtain a sand profile diagram, and obtain a continuous fine-tuning curve based on the sand profile diagram using an equidistant line method. The continuous fine-tuning curve includes straight line segments and / or arc segments. In this embodiment, the continuous fine-tuning curve is output as a two-dimensional electronic DXF drawing file.

[0090] Specifically, the equidistant line method is as follows: the normal outer equidistant line of the sand profile curve in the sand profile diagram is drawn to obtain the continuous finishing curve of the grinding wheel. The equidistant distance of the normal outer equidistant line is the radius r of the tool tip arc B11. d . In this embodiment, CAD software is used for drawing. Since special-shaped grinding wheels are mostly used for combined grinding of outer circles, conical surfaces, end faces, and shaft shoulders, their grinding profile A is mostly a combination of straight-line segment grinding profile A1 and circular-arc segment grinding profile A2. Therefore, when drawing the continuous finishing curve B, it is divided into the following two cases: the connection of the straight-line segment continuous finishing curve B1 and the straight-line segment continuous finishing curve B1, and the connection of the straight-line segment B1 continuous finishing curve and the circular-arc segment continuous finishing curve B2, as shown in FIG. Figure 2 and Figure 3 shown.

[0091] S2: Extracting entity segment data information of the continuous fine-tuning curve to obtain fine-tuning trajectory information. In this embodiment, the entity segment data information of the continuous fine-tuning curve is extracted using the dxflib library function in MATLAB programming software. The fine-tuning trajectory information includes the curve type, the number of curve segments, and the curve position. Curve types include straight line segments and circular arc segments. The curve position of a straight line segment includes the starting point coordinates and end point coordinates of each straight line segment. The curve position of a circular arc segment includes the center coordinates, radius value, starting angle, and end angle of each circular arc segment.

[0092] S3: Preset the theoretical single cutting depth, discretize the continuous fine-tuning curve according to the theoretical single cutting depth and the fine-tuning trajectory information to obtain fine-tuning discrete points, and create a fine-tuning discrete trajectory according to the fine-tuning discrete points. The fine-tuning discrete points include straight line segment discrete points and / or arc segment discrete points. Each straight line segment discrete point is obtained by layered discretization of the straight line segment according to the theoretical single cutting depth of each straight line segment, and each arc segment discrete point is obtained by equal-angle discretization of the arc segment according to the theoretical single cutting depth of each arc segment.

[0093] S4: Constructing a profiling allowance distribution model; including: establishing a rough trimming boundary and a tool retraction position boundary based on the fine trimming discrete points according to the preset profiling allowance, obtaining a profiling allowance distribution model composed of the rough trimming boundary and the tool retraction position boundary, and creating a rough trimming trajectory according to the rough trimming boundary and the tool retraction position boundary.

[0094] S5: First, the grinding wheel is roughly dressed according to the rough dressing trajectory, and then the grinding wheel is finely dressed according to the fine dressing discrete trajectory.

[0095] In this embodiment, step S2 further includes the following steps: obtaining the number of curve segments of the straight line segment as n1, storing the data information of the curve position of the straight line segment in a matrix form in the first matrix L l ,but

[0096]

[0097] Where [x1, y1] is the coordinate of the starting point of the first straight line segment, and [x1′, y1′] is the coordinate of the end point of the first straight line segment; is the coordinate of the starting point of the n1th straight line segment, is the end point coordinate of the n1th straight line segment, [] is an empty matrix. When n1=0, there is no straight line segment, L l is an empty matrix.

[0098] In this embodiment, the number of curve segments n2 of the arc segment is obtained, and the data information of the curve position of the arc segment is stored in the second matrix L in a matrix form. c ,but:

[0099]

[0100] Where [xc1, yc1] is the coordinate of the center of the first arc segment, [r1] is the radius of the first arc segment; α1 and α1′ are the starting angle and ending angle of the first arc segment respectively; is the coordinate of the center of the n2th arc segment, is the radius of the n2th arc segment; are the starting angle and ending angle of the n2th arc segment respectively. When n2=0, there is no arc segment, L c is an empty matrix.

[0101] In this embodiment, Figure 4 As shown in the figure, b is the intersection of the straight line segment and the arc segment. In order to discretize the continuous fine-tuning curve and obtain the fine-tuning discrete trajectory, the step S3 is specifically as follows:

[0102] S3.1: Set the theoretical single cutting depth of the straight segment to sp and the theoretical single cutting depth of the arc segment to sp′. To ensure the service life of the dressing tool roller, the theoretical single cutting depth of the straight segment and the theoretical single cutting depth of the arc segment are usually selected to be between 0.002mm and 0.5mm.

[0103] S3.2: Obtain the number of discrete points of each straight line segment according to the theoretical single cutting depth of the straight line segment and the coordinates of the starting point and the end point of each straight line segment; in this embodiment, the details are as follows.

[0104] Get the number of discrete points Nl of the straight line segment according to the curve position of the straight line segment i ,

[0105] If |y i ′-y i |≤sp, then the starting point of the i-th straight line segment (x i ,y i ) and the end point (x i ′,y i ′) as discrete points, the number of discrete points:

[0106] Nl i =2;

[0107] Among them, i is the index of the number of straight line segments n1, y i and y i ′ are the ordinates of the starting point and the ending point of the i-th straight line segment respectively.

[0108] If |y i ′-y i |>sp, then the number of discrete points:

[0109]

[0110] Where ceil is the rounding up function.

[0111] Correct the theoretical single cutting depth sp of the straight line segment to obtain the actual single cutting depth ap of the straight line segment i , whose expression is:

[0112]

[0113] In this embodiment, the actual single cutting depth ap i It is used to compare with the theoretical single cutting depth sp of the straight line segment, so that the operator can understand the execution status.

[0114] The number of discrete points of each arc segment is obtained according to the theoretical single cutting depth of the arc segment, as well as the center coordinates, radius value, starting angle and ending angle of each arc segment.

[0115] The coordinates of the starting point and end point of each arc segment are calculated based on the coordinate expression of the arc segment. The coordinate expression of the arc segment is:

[0116]

[0117]

[0118] Among them, [xc j ,yc j ] is the coordinate of the center of the jth arc segment, r j is the radius of the jth arc segment; α j , α j ′ are the starting angle and ending angle of the jth arc segment, j is the index of the arc segment number n2, (xa j ,ya j ) is the coordinate of the starting point of the jth arc segment, (xa j ′,ya j ′) is the coordinate of the end point of the j-th arc segment.

[0119] And the end angle α j 'Perform angle correction to obtain the correction end angle α j ″, specifically:

[0120] When α j ′<α j When α j ″=α j ′+360°;

[0121] When α j ′>α j When α j ″=α j ′.

[0122] In this embodiment, the actual angle interval of the arc segment is obtained by correcting the termination angle.

[0123] Obtain the number of discrete points Nc according to the curve position of the arc segment j ,

[0124] If|ya j ′-ya j |≤sp′, then the starting point of the arc segment j (xa j ,ya j ) and the end point (xa j ′,ya j ′) as discrete points, the number of discrete points:

[0125] Nc j =2;

[0126] If|ya j ′-ya j |>sp′, then the number of discrete points:

[0127]

[0128] Where ceil is the rounding up function.

[0129] S3.3: Discretize the straight line segment in layers according to the number of discrete points of the straight line segment, and obtain the coordinates of the discrete points of the straight line segment. In this embodiment, specifically:

[0130] Use the interval equal division function to divide the Y axis interval of the straight line segment [y i ′,y i ] Generate Nl with equal spacing within the range i values, get the array My i , whose expression is:

[0131] My i =linspace(y i ′,y i ,Nl i );

[0132] Among them, the linspace function is an interval equal division function.

[0133] Use the interpolation function at the starting point of the straight line segment (x i ,y i ) and the end point (x i ′,y i ′) with array My i Nl in i The linear interpolation is performed on the values ​​to obtain Nl after linear interpolation. i An array Mx of corresponding horizontal coordinate values i , whose expression is:

[0134] Mx i =interp1([y i ,y i ′],[x i ,x i ′],My i ,′linear′);

[0135] Among them, interp1 is the interpolation function, and 'linear' is the linear interpolation method;

[0136] Using [Mx i ,My i ] represents the coordinates of discrete points of a straight line segment.

[0137] The arc segment is discretized at equal angles according to the number of discrete points of the arc segment, and the coordinates of the discrete points of the arc segment are obtained.

[0138] The angle interval [α j ,α j Generate Nc with equal spacing within the range of ″] j Angle values, get array Nα j , whose expression is:

[0139] Nα j =linspace(α j ,α j ″,Nc j );

[0140] According to the coordinate expression of the arc segment, the array Nα j Nc j Angle values ​​are calculated to obtain Nc j coordinate points, that is, the coordinates of the discrete points of the arc segment are obtained.

[0141] S3.4: Combine the coordinates of the discrete points of the straight line segment and the discrete points of the arc segment, and use the sorting function to sort the Y-axis coordinate values ​​of the combined discrete points in descending order to obtain a set of discrete points, i.e., the refined discrete points P. m (xp m ,yp m ); m = 1, 2, 3, ..., N, where N is the total number of discrete points of straight line segments and circular arc segments.

[0142] S3.5: Create a fine-tuning discrete trajectory based on the fine-tuning discrete points. The fine-tuning discrete trajectory is the tool tip center moving from top to bottom according to the coordinates of the fine-tuning discrete point P1 to P N The trajectory, such as Figure 5 shown.

[0143] like Figure 6 As shown, the upper end surface G1 of the grinding wheel layer is used as the X axis, and the lower end surface G2 of the grinding wheel layer is located below the X axis. Step S4 is specifically as follows:

[0144] S4.1: Establishing a rough trimming boundary D and a tool retraction position boundary E based on the fine trimming discrete points according to the preset profiling allowance to obtain a profiling allowance distribution model, including the following steps:

[0145] The profiling allowance includes the allowance value t1 and the rough trimming amount t2, and the fine trimming amount t3 = t1 - t2; the value range of the allowance value t1 is usually 0.5-5 mm, and the value range of the rough trimming amount t2 is usually 0.3-4.8 mm.

[0146] The retraction position boundary E is established on the equidistant line with a margin value t1 in the X-axis direction from the fine trimming discrete point, and the rough trimming boundary D is established on the equidistant line with a rough trimming amount t2 in the X-axis direction from the retraction position boundary. The coordinate point P of the rough trimming boundary D is: m ′(xp m ′,yp m ′) and the coordinate point P of the retraction position boundary E m ″(xp m ″,yp m The expression of ″) is:

[0147]

[0148] S4.2: Establish a rough trimming trajectory based on the rough trimming boundary D and the retraction position boundary E. The rough trimming trajectory includes the initial rough trimming path and the cyclic rough trimming path unit. Figure 7 As shown, the initial rough finishing path includes an initial rough cutting path and an initial tool retraction path. The initial rough cutting path is a path where the tool tip center moves from P1″ to P1′, and the initial tool retraction path is a path where the tool tip center moves from P1′ to P1″. Specifically, Figure 7 Path ① and path ② in .

[0149] The rough finishing path unit includes a feed path, a unit rough cutting path and a unit retract path which are set in sequence. The feed path is the path from the tool tip center to the P q Move to P q+1 ″path, the unit cutting path is the tool tip center from P q+1 Move to P q+1 ′, the unit retraction path is the tool tip center from P q+1 ' moves toward P q+1 ″, where q is 1, 2, ..., N-1. Specifically: Figure 7 Path ③, path ④, path ⑤, ... in the .

[0150] In this embodiment, the tool retraction boundary E is located outside the grinding wheel layer blank boundary F.

[0151] When the method of the present invention is specifically implemented, it is assumed that the profile of a certain specification sand is as follows Figure 8 As shown in Figure 1, the sand profile consists of 2 straight line segments and 3 arc segments. The continuous fine-tuning curve extracted by MATLAB software is shown in Figure 1. Figure 9 As shown in the figure, there are 5 solid segments, 2 straight line segments, and 3 arc segments, that is, n=5, n1=2, and n2=3.

[0152] Store the curve position of the straight line segment in matrix L in matrix form l middle:

[0153]

[0154] Matrix L l The first row [11.373,-8.464] and [11.373,-11] are the starting point and end point coordinates of the first straight line segment; the second row [10.684,-1.333] and [9.566,1] are the starting point and end point coordinates of the second straight line segment.

[0155] The curve position of the arc segment is stored in the matrix L in matrix form c middle:

[0156]

[0157] Matrix L c The first line [12.373,-8.464] is the center coordinate of the first arc segment, and [1] is the radius value of the first arc segment; [270,330.001] are the starting angle and ending angle of the first arc segment respectively; the second line [12.487,-0.469] is the center coordinate of the second arc segment, and [2] is the radius value of the second arc segment; [205.012,244.406] are the starting angle and ending angle of the second arc segment respectively; the third line [10.373,-5] is the center coordinate of the third arc segment, and [3] is the radius value of the third arc segment; [25.012,150] are the starting angle and ending angle of the third arc segment respectively.

[0158] In this embodiment, when discretizing the straight line segment, sp = 0.5 mm is used. For the discretization of the first straight line segment, since |y1'-y1| = |-11-(-8.464)| = 2.536 > sp = 0.5, the two endpoints of the straight line segment in the Y-axis direction are greater than the theoretical single cutting depth of the straight line segment. Therefore, the number of discrete points for the first straight line segment is:

[0159]

[0160] The actual single cutting depth at this time is:

[0161] The linspace function in Matlab software can be used to realize the equal division of the interval. The specific syntax is as follows: My1=linspace(-11,-8.464,7)=(-11,-10.577,-10.155,-9.732,-9.309,-8.887,-8.464), that is, Nl1=7 values ​​are generated at equal intervals in the Y-axis interval [-11,-8.464]. These 7 values ​​are represented by My1, and My1 is an array of 1 row and 7 columns. Then use the interpolation function interp1 in MATLAB software to realize the linear interpolation of the two end points of the straight line segment. The specific syntax is as follows: Mx1=interp1([-8.464,-11],[11.373,11.373],My1,'linear')=(11.373,11.373,11.373,11.373,11.373,11.373,11.373), that is, on the straight line connecting the two points [11.373,-8.464] and [11.373,-11], the 7 values ​​in the array My1 are used as Y value variables through linear interpolation. Interpolation obtains 7 corresponding X values. 'linear' is the linear interpolation method. Mx1 is the set of 7 corresponding X values ​​obtained after linear interpolation, which is an array of 1 row and 7 columns. Therefore, [Mx1, My1] can be used to represent the coordinates of the 7 discrete points of the straight line segment. The coordinates of the discrete points are as follows: [11.373, -11], [11.373, -10.577], [11.373, -10.155], [11.373, -9.732], [11.373, -9.309], [11.373, -8.887], [11.373, -8.464].

[0162] Similarly, the second straight line segment can be discretized according to the above method.

[0163] For the discretization of the arc segment, sp′=0.5mm is also used. Before discretizing the first arc segment, the coordinates of the two end points of the arc segment must be calculated, and α1=270<α'1=330.001 must be satisfied. The calculation method is as follows:

[0164] Coordinates of the starting point of the first arc segment:

[0165] Coordinates of the end point of the first arc segment:

[0166] Therefore, the coordinates of the starting point of the first arc segment are [11.373, -8.464], and the coordinates of the end point are [11.873, -7.598]. Since |-8.464-(-7.598)|=0.866>sp′=0.5, the two endpoints of the arc segment in the Y-axis direction are greater than the theoretical single cutting depth of the arc segment. Therefore, the number of discrete points of the first arc segment is:

[0167]

[0168] The arc segment is divided into (Nc1-1)=(3-1)=2 parts according to the angle. That is, the interval division function can be realized by using the linspace function in the Matlab software. The specific syntax is as follows: linspace(270°, 330.001°, 3)=(270°, 300.0005°, 330.001°), that is, Nc1=3 angle values ​​are generated at equal angles within the angle interval [270°, 300.001°]. Then the equally divided angles of the arc segment are: Δα=300.0005°-270°=330.001°-300.0005°=30.0005°. Substituting the three angle values ​​into the coordinate expression of the arc segment in turn, we can obtain three discrete coordinate points. The calculated discrete point coordinates are [11.373, -8.464], [11.507, -7.964], and [11.873, -7.598].

[0169] Similarly, the discretization of the second arc segment and the third arc segment is completed in sequence according to the above method.

[0170] Finally, the coordinates of the discrete points of the straight line segment and the coordinates of the discrete points of the arc are merged, and the Y coordinate values ​​of the discrete points are sorted in descending order using the sort function in the matlab software. A set of 31 discrete points with Y coordinate values ​​from large to small is obtained. The obtained discrete points are shown in Table 1, that is, the refined discrete points are obtained. The distribution of the refined discrete points is shown in Table 1. Figure 10 As shown in the simulation diagram of the refined discrete trajectory Figure 11 As shown, Figure 11 In the figure, C is the discrete trajectory of fine finishing, and A is the sand contour.

[0171] Table 1 Coordinates of refined discrete points

[0172]

[0173]

[0174] In this embodiment, when establishing the profiling allowance distribution model, taking into account factors such as irregular deformation during the sintering process of the grinding wheel block, the allowance value is set to t1 = 3 mm, the rough dressing amount t2 = 2.8 mm, and the fine dressing amount t3 = t1-t2 = 0.2 mm. The calculated coordinate points of the rough dressing boundary are shown in Table 2, and the calculated coordinate points of the retraction position boundary are shown in Table 3.

[0175] Table 2 Coordinate points of rough trimming boundary

[0176] quantity coordinate quantity coordinate quantity coordinate 1 [9.766，1] 12 [12.794，-2.982] 23 [11.707，-7.964] 2 [9.990，0.533] 13 [13.148，-3.459] 24 [11.573，-8.464] 3 [10.213，0.067] 14 [13.401，-3.997] 25 [11.573，-8.464] 4 [10.437，-0.400] 15 [13.543，-4.573] 26 [11.573，-8.887] 5 [10.660，-0.866] 16 [13.569，-5.167] 27 [11.573，-9.309] 6 [10.884，-1.333] 17 [13.477，-5.754] 28 [11.573，-9.732] 7 [10.884，-1.333] 18 [13.272，-6.311] 29 [11.573，-10.155] 8 [11.280，-1.890] 19 [12.961，-6.817] 30 [11.573，-10.577] 9 [11.842，-2.281] 20 [12.556，-7.252] 31 [11.573，-11] 10 [11.842，-2.281] 21 [12.073，-7.598] 11 [12.353，-2.585] 22 [12.073，-7.598]

[0177] Table 3 Coordinate points of the retraction position boundary

[0178] quantity coordinate quantity coordinate quantity coordinate 1 [12.566，1] 12 [15.594，-2.982] 23 [14.507，-7.964] 2 [12.790，0.533] 13 [15.948，-3.459] 24 [14.373，-8.464] 3 [13.013，0.067] 14 [16.201，-3.997] 25 [14.373，-8.464] 4 [13.237，-0.400] 15 [16.343，-4.573] 26 [14.373，-8.887] 5 [13.460，-0.866] 16 [16.369，-5.167] 27 [14.373，-9.309] 6 [13.684，-1.333] 17 [16.277，-5.754] 28 [14.373，-9.732] 7 [13.684，-1.333] 18 [16.072，-6.311] 29 [14.373，-10.155] 8 [14.080，-1.890] 19 [15.761，-6.817] 30 [14.373，-10.577] 9 [14.642，-2.281] 20 [15.356，-7.252] 31 [14.373，-11] 10 [14.642，-2.281] 21 [14.873，-7.598] 11 [15.153，-2.585] 22 [14.873，-7.598]

[0179] Therefore, the simulation diagram of the rough trimming trajectory is as follows: Figure 12 As shown, Figure 12 In the figure, H is the coarse trimming trajectory.

[0180] In this embodiment, the range of the rough trimming feed speed v1 is 10-50 mm / min, the range of the rough trimming cutting speed v2 is 10-20 mm / min, and the range of the fine trimming cutting speed v3 is 2-10 mm / min.

[0181] In this embodiment, when performing rough trimming, the feed speed is set to v1 = 20 mm / min, and the rough trimming cutting speed is set to v2 = 10 mm / min. First, the initial rough trimming path is executed. After the initial rough trimming path is completed, the rough trimming path unit is executed cyclically until the center of the tool tip retreats to the coordinate point P on the boundary of the retraction position. N After the rough trimming is completed, the fine trimming process begins. When fine trimming is performed, the fine trimming cutting speed is set to v3 = 5mm / min, and the tool tip center moves from top to bottom according to the discrete point coordinate P1. N Finally, the finishing is completed.

[0182] The present invention realizes the automation of grinding wheel dressing by discretizing the grinding wheel dressing trajectory and designing the profiling allowance path. At the same time, by setting the fine dressing discrete trajectory and the coarse dressing trajectory, the flexibility and accuracy of grinding wheel dressing are improved, the versatility is improved, and the flexible dressing processing of special-shaped grinding wheels is realized.

[0183] The above are merely preferred embodiments of the present invention, but the scope of protection of the present invention is not limited thereto. Any changes or substitutions that can be easily conceived by a person skilled in the art within the technical scope disclosed in this invention should be included within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be based on the scope of protection defined by the claims.

Claims

1. A flexible dressing method for complex surface grinding wheels, characterized in that: The following steps are involved: S1: obtaining a sand profile diagram, and obtaining a continuous fine-tuning curve according to the sand profile diagram using an equidistant line method, wherein the continuous fine-tuning curve includes straight line segments and / or circular arc segments; S2: extracting entity segment data information of the continuous fine-tuning curve to obtain fine-tuning trajectory information, wherein the fine-tuning trajectory information includes curve type, number of curve segments, and curve position. The curve type includes straight line segments and circular arc segments. The curve position of the straight line segment includes the starting point coordinates and the end point coordinates of each straight line segment. The curve position of the circular arc segment includes the center coordinates, radius value, starting angle, and ending angle of each circular arc segment. S3: Preset a theoretical single cutting depth, discretize the continuous fine-tuning curve according to the theoretical single cutting depth and fine-tuning trajectory information to obtain fine-tuning discrete points, and create a fine-tuning discrete trajectory according to the fine-tuning discrete points, wherein the fine-tuning discrete points include straight line segment discrete points and / or arc segment discrete points, and each straight line segment discrete point is obtained by performing layered discretization on the straight line segment according to the theoretical single cutting depth of each straight line segment, and each arc segment discrete point is obtained by performing equal-angle discretization on the arc segment according to the theoretical single cutting depth of each arc segment; S4: constructing a profiling allowance distribution model; including: establishing a rough trimming boundary and a tool retraction position boundary based on the fine trimming discrete points according to the preset profiling allowance, obtaining a profiling allowance distribution model composed of the rough trimming boundary and the tool retraction position boundary, and creating a rough trimming trajectory according to the rough trimming boundary and the tool retraction position boundary; S5: Firstly, the grinding wheel is roughly dressed according to the rough dressing trajectory, and then the grinding wheel is finely dressed according to the fine dressing discrete trajectory.

2. The flexible dressing method for complex-surface grinding wheels according to claim 1, characterized in that: The equidistant line method in step S1 is: draw the normal outer equidistant line of the sand contour curve in the sand contour diagram to obtain the continuous finishing curve of the grinding wheel, and the equidistant distance of the normal outer equidistant line is the radius of the tool tip arc r d ; In step S2, the dxflib library function is used to extract the entity segment data information of the continuous fine-tuning curve.

3. The flexible dressing method for complex-surface grinding wheels according to claim 1, characterized in that: The step S2 further includes the following steps: obtaining the number of curve segments of the straight line segment as n1, storing the data information of the curve position of the straight line segment in a matrix form in a first matrix L l ,but: Where [x1, y1] is the coordinate of the starting point of the first straight line segment, and [x1′, y1′] is the coordinate of the end point of the first straight line segment; is the coordinate of the starting point of the n1th straight line segment, is the coordinate of the end point of the n1th straight line segment, [] is an empty matrix; Obtain the number of curve segments n2 of the arc segment, and store the data information of the curve position of the arc segment in the second matrix L in matrix form. c ,but: Where [xc1, yc1] is the coordinate of the center of the first arc segment, [r1] is the radius of the first arc segment; α1 and α1′ are the starting angle and ending angle of the first arc segment respectively; is the coordinate of the center of the n2th arc segment, is the radius of the n2th arc segment; They are the starting angle and ending angle of the n2th arc segment respectively.

4. The flexible dressing method for complex-surface grinding wheels according to claim 1, characterized in that: The step S3 is specifically as follows: S3.1: Set the theoretical single cutting depth of the straight line segment to sp, and set the theoretical single cutting depth of the arc segment to sp′; S3.2: Obtain the number of discrete points for each straight line segment based on the theoretical single cutting depth of the straight line segment and the coordinates of the starting point and the ending point of each straight line segment. Obtain the number of discrete points for each arc segment based on the theoretical single cutting depth of the circular arc segment and the coordinates of the center point, radius, starting angle, and ending angle of each arc segment. S3.3: Discretize the straight line segments in layers according to the number of discrete points of the straight line segments to obtain the coordinates of the discrete points of the straight line segments; discretize the arc segments in equal angles according to the number of discrete points of the arc segments to obtain the coordinates of the discrete points of the arc segments; S3.4: Combine the coordinates of the discrete points of the straight line segment and the discrete points of the arc segment, and use the sorting function to sort the Y-axis coordinate values ​​of the combined discrete points in descending order to obtain a set of discrete points, i.e., the refined discrete points P. m (xp m ,yp m ); m = 1, 2, 3, ..., N, where N is the total number of discrete points of straight line segments and circular arc segments; S3.5: Create a fine-finishing discrete trajectory based on the fine-finishing discrete points. The fine-finishing discrete trajectory is the movement of the tool tip center from top to bottom according to the coordinates of the fine-finishing discrete points P1 to P N trajectory.

5. The flexible dressing method for complex-surface grinding wheels according to claim 4, characterized in that: The discrete points of each straight line segment are obtained according to the theoretical single cutting depth of the straight line segment and the coordinates of the starting point and the end point of each straight line segment in step S3.2, specifically: Get the number of discrete points Nl of the straight line segment according to the curve position of the straight line segment i , If |y i ′-y i |≤sp, then the starting point of the i-th straight line segment (x i ,y i ) and the end point (x i ′,y i ′) as discrete points, the number of discrete points: Nl i ＝2； Among them, i is the index of the number of straight line segments n1, y i and y i ′ are the ordinates of the starting and ending points of the i-th straight line segment respectively; If |y i ′-y i |>sp, then the number of discrete points: Where ceil is the rounding up function.

6. The flexible dressing method for complex-surface grinding wheels according to claim 5, characterized in that: The step S3.2 also includes: correcting the theoretical single cutting depth sp of the straight line segment to obtain the actual single cutting depth ap i , whose expression is:

7. The flexible dressing method for complex-surface grinding wheels according to claim 4, characterized in that: The step S3.3 is to discretize the straight line segments in layers according to the number of discrete points of the straight line segments, and obtain the coordinates of the discrete points of the straight line segments, specifically: Use the interval equal division function to divide the Y axis interval of the straight line segment [y i ′,y i ] Generate Nl with equal spacing within the range i values, get the array My i , whose expression is: My i =linspace(y i ′,y i ,Nl i ); Among them, the linspace function is an interval equal division function; Use the interpolation function at the starting point of the straight line segment (x i ,y i ) and the end point (x i ′,y i ′) with array My i Nl in i The linear interpolation is performed on the values ​​to obtain Nl after linear interpolation. i An array Mx of corresponding horizontal coordinate values i , whose expression is: Mx i =interp1([y i ,y i ′],[x i ,x i ′],My i ,′linear′); Among them, interp1 is the interpolation function, and 'linear' is the linear interpolation method; Using [Mx i ,My i ] represents the coordinates of discrete points of a straight line segment.

8. The flexible dressing method for complex-surface grinding wheels according to claim 4, characterized in that: The discrete points of each arc segment are obtained according to the theoretical single cutting depth of the arc segment, the center coordinates, radius value, starting angle and ending angle of each arc segment in step S3.2, specifically: The coordinates of the starting point and the end point of each arc segment are calculated according to the coordinate expression of the arc segment. The coordinate expression of the arc segment is: Among them, [xc j ,yc j ] is the coordinate of the center of the jth arc segment, r j is the radius of the jth arc segment; α j , α j ′ are the starting angle and ending angle of the jth arc segment, j is the index of the arc segment number n2, (xa j ,ya j ) is the coordinate of the starting point of the jth arc segment, (xa j ′,ya j ′) is the coordinate of the end point of the j-th arc segment; And the end angle α j 'Perform angle correction to obtain the correction end angle α j Specifically: When α j ′ < α j then, α j ″ = α j ′ + 360°; When α j ′ > α j , then α j ″ = α j ′; Obtain the number of discrete points Nc according to the curve position of the arc segment j , If|ya j ′-ya j |≤sp′, then the starting point of the arc segment j (xa j ,ya j ) and the end point (xa j ′,ya j ′) as discrete points, the number of discrete points: Nc j =2; If|ya j ′-ya j |>sp′, then the number of discrete points: Where ceil is the rounding up function.

9. The flexible dressing method for complex-surface grinding wheels according to claim 4, characterized in that: In step S3.3, the arc segment is discretized at equal angles according to the number of discrete points of the arc segment, and the coordinates of the discrete points of the arc segment are obtained, specifically: The angle interval [α j ,α j Generate Nc with equal spacing within the range of ″] j Angle values, get array Nα j , whose expression is: Yes j =linspace(a j ,a j ″,Nc j ); According to the coordinate expression of the arc segment, the array Nα j Nc j Angle values ​​are calculated to obtain Nc j coordinate points, that is, the coordinates of the discrete points of the arc segment are obtained.

10. The flexible dressing method for complex-surface grinding wheels according to claim 4, characterized in that: The step S4 is specifically as follows: S4.1: Establishing a rough trimming boundary and a tool retraction position boundary based on the fine trimming discrete points according to the preset profiling allowance to obtain a profiling allowance distribution model, including the following steps: The profiling allowance includes the allowance value t1 and the rough trimming amount t2, and the fine trimming amount t3 = t1 - t2; Establish the retraction position boundary on the equidistant line with a margin value t1 in the X-axis direction from the fine finishing discrete point. A rough trimming boundary is established on an equidistant line that is a rough trimming amount t2 away from the retraction position boundary in the X-axis direction. Then the coordinate point P of the rough trimming boundary m ′(xp m ′,yp m ′) and the coordinate point P of the retraction position boundary m ″(xp m ″,yp m The expression of ″) is: S4.2: Establish a rough trimming trajectory according to the rough trimming boundary and the tool retraction position boundary, wherein the rough trimming trajectory includes an initial rough trimming path and a cyclic rough trimming path unit. The initial rough finishing path includes an initial rough cutting path and an initial tool retraction path, wherein the initial rough cutting path is a path where the tool tip center moves from P1″ to P1′, and the initial tool retraction path is a path where the tool tip center moves from P1′ to P1″; The rough finishing path unit includes a feed path, a unit rough cutting path and a unit retract path which are arranged in sequence. The feed path is a path from the center of the tool tip to the path of the tool tip. q Move to P q+1 ″path, the unit cutting path is the tool tip center by P q+1 Move to P q+1 'path, the unit retraction path is the tool tip center by P q+1 ' moves toward P q+1 ″ path, where q is 1, 2, ..., N-1.

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