阅读说明：本技术 一种偏光片角部凸圆弧近似加工的方法 (Approximate processing method for convex circular arc of corner of polaroid ) 是由 贾霞彦 赵莹 李铁 李想 康亮兵 于 2021-10-18 设计创作，主要内容包括：本发明公开了一种偏光片角部凸圆弧近似加工的方法,刀盘的移动方向与工件的移动方向垂直,工件能够绕其中心旋转；矩形的偏光片作为工件,在偏光片角部用多段加工完成的直线近似圆弧,直线是采用等分圆弧的切线,即：对偏光片角部需要加工的圆弧段进行等角度划分为多段圆弧,用每段圆弧划分点处的切线拟合成圆弧；每次加工一段圆弧的切线,下次加工相邻圆弧的切线,直至完成全部等分次数切线的加工后形成一个近似圆弧。本发明方法可以完成偏光片角部凸圆弧的近似加工和非45度倒角的加工,拓展了设备的应用范围,满足了不同客户的需求。(The invention discloses a method for approximate processing of convex circular arcs at corners of a polaroid, wherein the moving direction of a cutter head is vertical to the moving direction of a workpiece, and the workpiece can rotate around the center of the cutter head; the polaroid of rectangle is as the work piece, and the straight line that accomplishes is similar to the circular arc at polaroid bight with multistage processing, and the straight line is the tangent line that adopts the bisector circular arc, promptly: dividing the arc sections of the corner of the polaroid needing to be processed into a plurality of sections of arcs in an equal angle manner, and fitting the tangent line at the dividing point of each section of arc into an arc; the tangent of one section of circular arc is processed each time, the tangent of the adjacent circular arc is processed next time, and an approximate circular arc is formed until the processing of all the tangent lines with equal times is completed. The method can complete the approximate processing of the convex arc at the corner of the polaroid and the processing of the chamfer with the angle different from 45 degrees, expand the application range of equipment and meet the requirements of different customers.)

1. A method for approximate processing of convex circular arcs at corners of a polaroid is characterized in that: the moving direction of the cutter head is vertical to the moving direction of the workpiece, and the workpiece can rotate around the center of the cutter head; the polaroid of rectangle is as the work piece, and the straight line that accomplishes is similar to the circular arc at polaroid bight with multistage processing, and the straight line is the tangent line that adopts the bisector circular arc, promptly: dividing the arc sections of the corner of the polaroid needing to be processed into a plurality of sections of arcs in an equal angle mode, and fitting the tangent lines at the dividing points of each section of arc into approximate arcs; processing the tangent of one section of arc each time, and processing the tangent of the adjacent arc next time until the processing of all the equally divided times of tangents is completed to form an approximate arc; the method specifically comprises the following steps:

firstly, determining parameters of corner processing circular arcs, comprising the following steps: the integral range of the corner to be processed, the quasi-equal times of processing arcs, the radius of each arc and the angle of each arc;

if the corner consists of a plurality of sections of circular arcs and straight lines, determining the quasi-equal times of each section of circular arc, the radius of each circular arc and the angle of each circular arc;

if the corner consists of a section of circular arc, determining the quasi-equal times, the radius and the angle of the circular arc of the section of circular arc;

if the corner part is a straight line, determining the processing range of the corner part of the workpiece;

secondly, calculating the angle of the workpiece needing to rotate, the actual cutting amount, the position of the cutter head in moving and the cutting distance when the workpiece is cut when a first section of arc directly connected with the side edge of the workpiece is processed;

thirdly, processing the arc for multiple times according to the arc quasi-equal times when processing the arc, firstly processing a first section of arc directly connected with the side edge of the workpiece, namely processing a tangent line of a first equal angle; after the machining is finished, the cutter head and the workpiece return respectively, the calculation in the second step is repeated, and the tangent line of the second bisector angle is machined again; after the machining is finished, the cutter head and the workpiece return respectively, and calculation and machining are carried out to and fro in sequence until the equal division times are finished, so that the first section of circular arc machining is finished;

if the whole corner is only provided with a section of circular arc, the processing of the convex circular arc of the corner is declared to be finished without continuous processing;

if the corner part is a straight line, the processing can be finished only once;

fourthly, when the whole corner consists of a plurality of sections of circular arcs and straight lines, the step begins to process the straight lines connected with the first section of circular arcs or the second section of circular arcs; returning to the second step due to the machined angle and the machined angle range in the third step, calculating parameter values again after adding the angle required at the time, and repeating the calculation and machining processes in the second step and the third step until the straight line or the circular arc is machined;

and fifthly, repeating the second, third and fourth steps until the whole corner curve is processed.

2. The method for approximate processing of convex circular arcs at corners of a polarizer according to claim 1, wherein: in the second step, the rotation angle of the workpiece is calculated: when the arc is formed, the rotation angle is calculated according to the arc angle, the number of times of equal division and the number of times of processing; when the chamfer angle is a straight chamfer angle, calculating a rotation angle by using an inverse trigonometric function according to the input corner parameters;

calculation of actual cut: calculating the value of the cutting amount according to the rotation angle and the arc radius; the first section of cutting amount represents the cutting amount corresponding to the first section of circular arc, and the second section of cutting amount represents the cutting amount corresponding to the second section of circular arc; and so on;

calculating the moving position of the cutter head: actually, calculating the distance between the rotation center of the workpiece and a tangent line at the arc of the equal section to be processed; calculating the distance according to the geometric relationship among the sizes of the long edge and the short edge of the workpiece, the rotation angle, the radius of the arc and the tangent;

calculation of cutting distance when the workpiece is cut: after the cutter disc moves to the right position, the distance from the workpiece to the cutting point of the cutter disc and the cutting distance from the cutting point to the cutting completion after the workpiece continues to move the cutter disc are calculated according to the geometric relation, so that the idle stroke of the workpiece movement is effectively compressed.

3. The method for approximate machining of convex arcs at corners of a polarizer according to claim 2, wherein: the cutter head movement position is calculated as follows: the corner part is composed of a section of approximately convex circular arc KGS, wherein the radius of the circular arc is R, the angle of the circular arc is theta, and the number of quasi-equal division times is N;

the central point of the rectangular workpiece is O; setting: before the arc KGS is processed, the long edge of the workpiece is perpendicular to the moving direction of the cutter head, two end points, close to the long edge of the cutter head, on the workpiece are marked as B 'and A', and two end points, far away from the long edge of the cutter head, on the workpiece are marked as D 'and C'; the arc endpoint K is a tangent point of the arc and the short edge of the workpiece, the arc endpoint S is a tangent point of the arc and the long edge of the workpiece, the arc point G is a tangent point corresponding to the tangent line of the first bisector angle, and the circle center corresponding to the arc KGS is an L point; at the moment, the rotation angle of the workpiece after anticlockwise rotation is alpha, the point B 'of the workpiece rotates to the point B, the point A' of the workpiece rotates to the point A, the point C 'of the workpiece rotates to the point C, and the point D' of the workpiece rotates to the point D;

OE and OJ are respectively central extension lines of the rectangular workpiece, EJ is a tangent line of an arc KGS passing through a G point, OH is a perpendicular line perpendicular to EJ passing through the O point and intersected with A 'B' at a T point, EJ and A 'B' are parallel in the process and perpendicular to the moving direction of the cutter head, and LKB is a square with the radius R;

the moving position OH of the cutter head is calculated as follows:

workpiece long side B 'a' = x, workpiece short side a 'D' = y, arc radius = R, rotation angle = α

Then: OH = OJ cos α:. DELTA. OHJ

=(OP+PJ)*cosα

=(y/2+PQtanα)*cosα:△PQJ

=(y/2+(PB–BQ)tanα)*cosα

=(y/2+(x/2–BQ)tanα)*cosα

=(y/2+(x/2–(BS–QS))tanα)*cosα:LKBS

=(y/2+(x/2–(R–R*tan(α/2)))tanα)*cosα :△LSQ

Namely: moving the cutter head to the straight line where EJ is located;

the cutting distance when the workpiece was cut was calculated as follows:

the extension line section B' V of the short side of the rectangular workpiece is intersected with the left extension of EJ at a V point;

making a perpendicular line from the point B to the point A 'B' to intersect at the point N and intersect with the point VJ at the point U;

linking OB ', OB and BB';

f is the intersection point of BC and VJ, G is the tangent point, and U is the intersection point of VJ and BN;

calculation of B' N:

b 'N = B' B cos BB 'N isosceles Delta OBB'

=2*OB*sin(α/2)*cos∠BB’N

=2*(*sin(α/2))*cos(∠BB’O-∠NB’O)

=2*(*sin(α/2))*cos((180–α)/2–arctan(y/x))

VF=B’N–FU

=B’N-BF*sinα=B’N–(R–R*tan((90–α)/2))*sinα

VQ=B’N+UQ

=B’N+BQ*cosα=B’N+(R–R*tan(α/2))*cosα

FQ= VQ–VF

Namely: the distance from the workpiece to the cutting point moving to the cutter head is VF; the cutting distance from the cutting point to the cutting completion after the workpiece continues to move the cutter disc to start cutting is FQ.

Technical Field

The invention relates to the technical field of side edge processing of liquid crystal polaroids, in particular to a method for approximately processing convex circular arcs at corners of a polaroid.

Background

The liquid crystal polaroid is a raw material for producing display screens of computers, mobile phones and the like, firstly the polaroid is cut into required sizes (the polaroid is generally rectangular), then the cut polaroids are stacked on edge grinding equipment to be subjected to milling processing of four sides, and the size precision of the sides and the quality of the processed surface of the liquid crystal polaroid meet the requirements of products. The specific process is as follows: the conveying table is provided with a plurality of pairs of clamps (each pair of clamps is divided into an upper clamp and a lower clamp), the stacked polaroids are arranged in the upper clamp and the lower clamp to be clamped and fixed (the polaroids can rotate along the centers of the clamps), the polaroids are conveyed to the processing position of the equipment by the conveying table, two servo motors on the equipment perpendicular to the moving direction of the conveying table drive two processing motors to move towards the polaroids in opposite directions for certain processing displacement, and a cutting rotating cutter disc on the processing motors cuts the stacked polaroids. The polarizer is rotated by 90 degrees or 45 degrees by a slicer or other rotating devices to finish the processing of four sides or chamfer the corners by 45 degrees. The convex arc processing or the approximate processing of the corner of the polaroid cannot be finished, and the chamfer processing of other angles cannot be finished.

Disclosure of Invention

The invention aims to provide a method for approximate processing of a convex circular arc at a corner of a polaroid, which solves the technical problems that the prior art cannot finish approximate processing of the convex circular arc at the corner of the polaroid and processing of a chamfer of not 45 degrees, and reduces the grinding of a cutter and improves the processing efficiency by controlling the processing allowance and the cutting stroke.

The invention is realized by adopting the following technical scheme:

a method for approximate processing of convex circular arcs at corners of a polaroid is disclosed, which has the following basic idea: the straight line processed by multiple sections is similar to an arc, the straight line adopts a tangent line which equally divides the arc, namely, the arc to be processed is equally divided into multiple sections of arcs by angle, and the tangent line of each section of arc is used for fitting the arcs. The tangent of one section of circular arc is processed each time, the tangent of the adjacent circular arc is processed next time, namely the tangent after an equal division angle is added, and the circular arcs are sequentially added and processed until all the equal division times are completed, so that an approximate circular arc is formed. In the machining process, according to the size of the equant angle and the radius of the arc, the cutting amount, namely the machining allowance can be calculated, whether multiple times of machining is needed or not is judged, and the abrasion of a cutter is reduced; according to the rotation angle and the arc radius, the movement amount of the workpiece, namely the cutting stroke, is determined, the machining idle stroke is reduced, and the machining efficiency is improved. Different arcs or the connection between the arcs and the straight line, when processing calculation is carried out, the processed arc angle needs to be added, and the purpose of processing the special-shaped arc at the corner of the polaroid is achieved through the combination of the arcs or the arcs and the straight line.

When the device is implemented, the moving direction of the cutter head is vertical to the moving direction of the workpiece, and the workpiece can rotate around the center of the cutter head; the polaroid of rectangle is as the work piece, and the straight line that accomplishes is similar to the circular arc at polaroid bight with multistage processing, and the straight line is the tangent line that adopts the bisector circular arc, promptly: dividing the arc sections of the corner of the polaroid needing to be processed into a plurality of sections of arcs in an equal angle manner, and fitting the tangent line at the dividing point of each section of arc into an arc; processing the tangent of one section of arc each time, and processing the tangent of the adjacent arc next time until the processing of all the equally divided times of tangents is completed to form an approximate arc; the method specifically comprises the following steps:

firstly, determining parameters of corner processing circular arcs, comprising the following steps: the integral range of the corner to be processed, the quasi-equal times of processing arcs, the radius of each arc and the angle of each arc;

if the corner consists of a plurality of sections of circular arcs and straight lines, determining the quasi-equal times of each section of circular arc, the radius of each circular arc and the angle of each circular arc;

if the corner consists of a section of circular arc, determining the quasi-equal times, the radius and the angle of the circular arc of the section of circular arc;

and if the corner part is a straight line, determining the machining range of the corner part of the workpiece.

Secondly, calculating the angle of the workpiece needing to rotate, the actual cutting amount, the position of the cutter head to move and the cutting distance of the workpiece when the workpiece is cut when a first section of arc directly connected with the side edge of the workpiece is machined;

wherein, the rotation angle of the workpiece is calculated as follows: when the arc is formed, the rotation angle is calculated according to the arc angle, the number of times of equal division and the number of times of processing; when the chamfer angle is a straight chamfer angle, calculating a rotation angle by using an inverse trigonometric function according to the input corner parameters;

calculation of actual cut: calculating the value of the cutting amount according to the rotation angle and the arc radius;

calculating the moving position of the cutter head: actually, calculating the distance between the rotation center of the workpiece and a tangent line at the arc of the equal section to be processed; calculating the distance according to the geometric relationship among the sizes of the long edge and the short edge of the workpiece, the rotation angle, the radius of the arc and the tangent;

calculation of cutting distance when the workpiece is cut: after the cutter disc moves to the right position, the distance from the workpiece to the cutting point of the cutter disc and the cutting distance from the cutting point to the cutting completion after the workpiece continues to move the cutter disc are calculated according to the geometric relation, so that the idle stroke of the workpiece movement is effectively compressed.

Thirdly, processing the arc for multiple times according to the arc quasi-equal times when processing the arc, firstly processing a first section of arc directly connected with the side edge of the workpiece, namely processing a tangent line of a first equal angle; after the machining is finished, the cutter head and the workpiece return respectively, the calculation in the second step is repeated, and the tangent line of the second bisector angle is machined again; after the machining is finished, the cutter head and the workpiece return respectively, and calculation and machining are carried out to and fro in sequence until the equal division times are finished, so that the first section of circular arc machining is finished;

if the whole corner is only provided with a section of circular arc, the processing of the convex circular arc of the corner is declared to be finished without continuous processing;

if the corner part is a straight line, the processing can be finished only once.

Fourthly, when the whole corner consists of a plurality of sections of circular arcs and straight lines, the step begins to process the straight lines connected with the first section of circular arcs or the second section of circular arcs; and returning to the second step due to the machined angle and the machined angle range in the third step, adding the required angle, calculating the parameter values again, and repeating the calculation and machining processes in the second step and the third step until the straight line or the circular arc is machined.

And fifthly, repeating the second, third and fourth steps until the whole corner curve (approximate convex arc) is processed.

The invention relates to a method for approximate processing of convex circular arcs at corners of a polaroid, which has the key points that: (1) and (5) processing by adopting an arc tangent to finish the approximate convex arc. (2) After one tangent line is machined each time, the cutter disc and the workpiece need to return respectively, the position of the cutter disc and the cutting distance of the workpiece are determined by calculation during machining each time, so that the idle stroke distance of workpiece movement each time is determined, the idle stroke is accurately compressed, and the machining efficiency is improved. Because the processed polaroid is a stack of polaroids, the tangent processing of the whole stack of polaroids can be finished after the workpiece needs to move for a certain distance, and a rectangular surface is formed. If the cutter disc is not separated from the polaroid, the cutter disc moves linearly back and forth and the workpiece rotates in an interpolation mode, only an arc on a certain lamination height can be completed, and other polaroids cannot cut the arc. In addition, due to the influence of the cutter head, the reciprocating machining cannot be performed, so that the workpiece and the cutter head need to return respectively after a section of tangent line is machined.

The method has reasonable design, can finish the approximate processing of the convex arc of the corner of the polaroid and the processing of the chamfer of the angle different from 45 degrees, expands the application range of equipment, meets the requirements of different customers and has good practical application value.

Drawings

FIG. 1 shows a corner parameter input reference schematic of the present invention.

Fig. 2 shows a reference diagram for calculating the actual cutting amount according to the present invention.

Fig. 3 shows a reference schematic diagram for the calculation of the cutterhead moving position of the present invention.

Fig. 4 shows a reference diagram for calculating the moving position of the workpiece according to the present invention.

FIG. 5 is a schematic flow chart of the process of the present invention.

FIG. 6 is a schematic view of the corner parameter input combination of the present invention.

Fig. 7 shows a comparison of three circular arcs.

Fig. 8 shows a partially enlarged view of fig. 7.

Detailed Description

The following detailed description of specific embodiments of the invention refers to the accompanying drawings.

A method for approximate processing of convex circular arcs at corners of a polaroid is characterized in that in actual processing, the moving direction of a cutter head is vertical to the moving direction of a workpiece, and the workpiece can rotate around the center of the cutter head; the polaroid of rectangle is as the work piece, and the straight line that accomplishes is similar to the circular arc at polaroid bight with multistage processing, and the straight line is the tangent line that adopts the bisector circular arc, promptly: dividing the arc sections of the corner of the polaroid needing to be processed into a plurality of sections of arcs in an equal angle manner, and fitting the tangent line at the dividing point of each section of arc into an arc; processing the tangent of one section of arc each time, and processing the tangent of the adjacent arc next time until the processing of all the equally divided times of tangents is completed to form an approximate arc; the method specifically comprises the following steps:

firstly, determining parameters of corner processing circular arcs, comprising the following steps: the integral range of the corner to be processed, the quasi-equal times of processing arcs, the radius of each arc and the angle of each arc;

if the corner consists of a plurality of sections of circular arcs and straight lines, determining the quasi-equal times of each section of circular arc, the radius of each circular arc and the angle of each circular arc;

if the corner consists of a section of circular arc, determining the quasi-equal times, the radius and the angle of the circular arc of the section of circular arc;

and if the corner part is a straight line, determining the machining range of the corner part of the workpiece.

In specific implementation, corner parameters required by the corner to be machined are input in a man-machine interaction mode. As shown in fig. 1, the right side view is an enlarged view of the corner portion B in the left side overall view. For convenience of description and actual operation, in the left overall view, the four corners of the workpiece are distinguished by A, B, C, D, the upper right corner is defined as a, the lower right corner is defined as B, the lower left corner is defined as C, and the upper left corner is defined as D, one group of corresponding sides of the rectangular workpiece is defined as Y, the other group of corresponding sides is defined as X, Δ X is the part of the workpiece processed in the X direction, and Δ Y is the part of the workpiece processed in the Y direction. The entire range of the corner a to be machined is AX, AY, the entire range of the corner B to be machined is BX, BY, the entire range of the corner C to be machined is CX, CY, and the entire range of the corner D to be machined is DX, DY, for example, the convex arc of the machined corner B shown in the enlarged view (right side view) in fig. 1 is composed of arcs on both sides and a straight line segment in the middle, the arc radii R1, R2 are each, the arc angles are θ 1, θ 2, and the pseudo-equal division numbers (machining number) of N1, N2, and the like. The corner parameter input format may be referred to in the form of fig. 6, with the parameters for each corner being distinguished by a prefix A, B, C, D.

And secondly, calculating the angle of the workpiece needing to rotate, the actual cutting amount, the position of the cutter head to move and the cutting distance of the workpiece when the first section of arc directly connected with the side edge of the workpiece is machined.

(1) Calculating the rotation angle of the workpiece: when the arc is adopted, the rotation angle is easy to calculate according to the arc angle, the equal division times and the numerical value of the processing for the time at this time; in the case of straight chamfering, the rotation angle can be easily calculated BY an inverse trigonometric function according to the relationship between the input parameters BX and BY. For example: in fig. 1, when the chamfer is a straight chamfer, the rotation angle α = arctan (BY/BX). In fig. 2, if the total arc angle is 3 α and the arc angle is 3 equal parts, the machining is performed twice, the rotation angle during the first machining is α, and the rotation angle during the second machining is 2 α.

(2) Calculation of actual cut: referring to fig. 2, the first cutting amount indicates a cutting amount of the first arc angle, and the second cutting amount indicates a cutting amount at the second arc angle. It can be seen from the figure that the value of the cutting amount can be calculated from the rotation angle α and the circular arc radius R. Note that when calculating the cut amount of the second step, the position of the start point of the cut amount is changed. And comparing the cutting quantity with the cutting quantity of the set cutter in the machining process to determine whether the current cutting needs to be separately machined for multiple times.

(3) Calculating the moving position of the cutter head: referring to fig. 3 (in this embodiment, the corner is only a circular arc), the value of the distance OH between the workpiece rotation center O and EJ is actually calculated. The distance of OH can be calculated from geometrical relationships such as the size of the long sides (B 'A' and D 'C') and the size of the short sides (B 'C' and A 'D'), the rotation angle alpha, the arc radius R, and the tangent of FIG. 3.

The cutter head movement position is calculated as follows: the corner part is composed of a section of approximately convex circular arc KGS, wherein the radius of the circular arc is R, the angle of the circular arc is theta, and the number of quasi-equal division times is N. The central point of the rectangular workpiece is O; setting: before the arc KGS is processed, the long edge of the workpiece is perpendicular to the moving direction of the cutter head, two end points, close to the long edge of the cutter head, on the workpiece are marked as B 'and A', and two end points, far away from the long edge of the cutter head, on the workpiece are marked as D 'and C'; the arc endpoint K is a tangent point of the arc and the short edge of the workpiece, the arc endpoint S is a tangent point of the arc and the long edge of the workpiece, the arc point G is a tangent point corresponding to the tangent line of the first bisector angle, and the circle center corresponding to the arc KGS is an L point; at this time, the rotation angle of the workpiece after counterclockwise rotation is α, the point B 'of the workpiece is rotated to the point B, the point a' is rotated to the point a, the point C 'is rotated to the point C, and the point D' is rotated to the point D.

OE and OJ are respectively central extension lines of the rectangular workpiece, EJ is a tangent line of an arc KGS passing through a G point, OH is a perpendicular line perpendicular to EJ passing through the O point and intersected with A 'B' at a T point, EJ and A 'B' are parallel in the process and perpendicular to the moving direction of the cutter head, and LKB is a square with the radius R;

the moving position OH of the cutter head is calculated as follows:

workpiece long side B 'a' = x, workpiece short side a 'D' = y, arc radius = R, rotation angle = α

Then: OH = OJ cos α:. DELTA. OHJ

=(OP+PJ)*cosα

=(y/2+PQtanα)*cosα:△PQJ

=(y/2+(PB–BQ)tanα)*cosα

=(y/2+(x/2–BQ)tanα)*cosα

=(y/2+(x/2–(BS–QS))tanα)*cosα:LKBS

=(y/2+(x/2–(R–R*tan(α/2)))tanα)*cosα :△LSQ

Namely: and moving the cutter head to the straight line of EJ.

(4) Calculation of cutting distance when the workpiece is cut: after the cutter disc moves to the right position, the distance from the workpiece to the cutting point of the cutter disc and the cutting distance from the cutting point to the cutting completion after the workpiece continues to move the cutter disc are calculated according to the geometric relation, so that the idle stroke of the workpiece movement is effectively compressed.

The cutting distance when the workpiece was cut was calculated as follows:

the extension line section B' V of the short side of the rectangular workpiece is intersected with the left extension of EJ at a V point;

making a perpendicular line from the point B to the point A 'B' to intersect at the point N and intersect with the point VJ at the point U;

linking OB ', OB and BB';

in fig. 4: the point F is the intersection point of BC and VJ, the point G is the tangent point of the circular arc KGS and VJ, and the point U is the intersection point of VJ and BN;

calculation of B' N:

b 'N = B' B cos BB 'N isosceles Delta OBB'

=2*OB*sin(α/2)*cos∠BB’N

=2*(*sin(α/2))*cos(∠BB’O-∠NB’O)

=2*(*sin(α/2))*cos((180–α)/2–arctan(y/x))

VF=B’N–FU

=B’N–BF*sinα=B’N–(R–R*tan((90–α)/2))*sinα

VQ=B’N+UQ

=B’N+BQ*cosα=B’N+(R–R*tan(α/2))*cosα

FQ= VQ–VF

Namely: the distance from the workpiece to the cutting point moving to the cutter head is VF; the cutting distance from the cutting point to the cutting completion after the workpiece continues to move the cutter disc to start cutting is FQ.

Therefore, the cutting distance is the distance between FQs in fig. 4, and for an effective compression idle stroke, the distance values of VF and VQ need to be calculated respectively, and then a safety margin is added appropriately, so that the front and rear specific positions moved during cutting can be obtained, and the compression idle stroke, that is, the workpiece can be moved quickly in the VF section and moved slowly (in the cutting process) in the FQ section, thereby improving the machining efficiency.

In this embodiment, the convex arc processing adopts a circumscribed polygon method for the following reasons:

as shown in fig. 7, there are three kinds of circular arc approximation methods. The left half is one, and the connection method is divided equally; the lower right corner has two kinds, namely an inscribed polygon method and a circumscribed polygon method. (1) The left half-halving connecting line method is to grind the rectangular corner into approximate circular arc, to cut off the length of the corner, to be divided equally according to the length, and then to connect each other; the upper left corner is 10 equal parts and the lower left corner is 20 equal parts, and the difference between the upper left corner and the lower left corner and the arc is the same and is lower than the accuracy of the method for circumscribing the polygon, so that the upper left corner and the lower left corner are abandoned. (2) After the angle is divided by 10, the precision of the difference between the circumscribed polygon and the arc is better than that of the left half pair, and the independent graph of the lower right corner is the difference. Therefore, this embodiment adopts this method. (3) The lower right hand corner is a method of comparing inscribed polygon and circumscribed polygon approximations. Under the same angular bisection condition, the inscribed polygon is processed more than the circumscribed polygon once. The lower right corner is equally divided into 4 corners, and the inner contact method is used for processing 4 times, and the outer contact method is used for processing 3 times. The three methods are compared and then a circumscribed polygon method is selected.

Thirdly, processing the arc for multiple times according to the arc quasi-equal times when processing the arc, firstly processing a first section of arc directly connected with the side edge of the workpiece, namely processing a tangent line of a first equal angle; after the machining is finished, the cutter head and the workpiece return respectively, the calculation in the second step is repeated, and the tangent line of the second bisector angle is machined again; after the machining is finished, the cutter head and the workpiece return respectively, and calculation and machining are carried out to and fro in sequence until the equal division times are finished, so that the first section of circular arc machining is finished;

if the whole corner is only provided with a section of circular arc, the processing of the circular arc or the straight line of the corner is declared to be finished without continuous processing;

if the corner part is a straight line, the processing can be finished only once.

Fourthly, when the whole corner consists of a plurality of sections of circular arcs and straight lines, the step begins to process the straight lines connected with the first section of circular arcs or the second section of circular arcs; the processing flow is performed according to fig. 5, but when the initial value is set in the flow of fig. 5, the angle already processed in the third step and the range of the already processed corner portion need to be considered, and then the processing of the arc or the straight line can be continued according to the flow of fig. 5. And returning to the second step, calculating the parameter values again after adding the current required angle, and repeating the calculation and processing processes of the second step and the third step until the linear or circular arc processing of the section is finished.

And fifthly, repeating the second, third and fourth steps until the whole corner curve is processed.

And finally, finishing the approximate convex circular arc processing of the four corners of the workpiece in sequence.

Finally, it should be noted that the above embodiments are only for illustrating the technical solutions of the present invention and not for limiting, and although the detailed description is made with reference to the embodiments of the present invention, it should be understood by those skilled in the art that modifications or equivalent substitutions may be made on the technical solutions of the present invention without departing from the spirit and scope of the technical solutions of the present invention, which shall be covered by the claims of the present invention.