阅读说明：本技术 一种使用磨损砂轮磨削周齿螺旋刃后刀面的补偿方法 (Compensation method for grinding rear cutter face of peripheral tooth spiral blade by using worn grinding wheel ) 是由 徐斌 李勇 于 2020-05-26 设计创作，主要内容包括：本发明公开了一种使用磨损砂轮磨削周齿螺旋刃后刀面的补偿方法,首先定义磨削加工的砂轮补偿参考平面,并在补偿参考平面中计算砂轮棱边几何形状函数,最终通过求解不同磨削工艺参数的砂轮补偿向量,得到数控程序的坐标调整量。本发明能有效减少由于砂轮棱边磨损导致的周齿螺旋刃后刀面磨削加工误差。(The invention discloses a compensation method for grinding a rear cutter face of a peripheral tooth spiral blade by using a worn grinding wheel. The invention can effectively reduce the grinding processing error of the rear cutter face of the peripheral tooth spiral blade caused by the abrasion of the edge of the grinding wheel.)

1. A compensation method for grinding a back tool face of a peripheral tooth spiral blade by using a wear grinding wheel is characterized by comprising the following steps:

step 1: compensated reference plane definition

Make the central axis of the cutter be Z_wThe center of a circle of the end surface of the revolving body of the shaft and the cutter is the origin O_wThe end face where the starting point of the blade is located is X_wO_wY_wPlane, establishing a workpiece coordinate system O_w-X_wY_wZ_w(ii) a In the workpiece coordinate system, a grinding point P on a designated point, namely an edge line, on the spiral edge is determined to correspond to three reference planes, namely base planes P_rCutting plane P_sTo the orthogonal plane P_oThe position of (a);

the three reference planes are space planes, and the section lines of the rear cutter face in the orthogonal plane are space line segments; to facilitate the description of the transversal model, a moving coordinate system O is established_o-X_oY_oZ_o(ii) a Origin O of the coordinate system_oCoincident with the grinding point P on the edge line, axis X_oOn the intersection of the basal plane and the orthogonal plane, axis Y_oOn the intersection of the cutting plane and the orthogonal plane, the axis Z_oOn the intersection line of the cutting plane and the base plane;

step 2: calculating the edge geometry function of the grinding wheel

In the actual use of the grinding wheel, the grinding process is complex and changeable, so that the shape of the edge of the grinding wheel can be changed due to different working conditions; according to the design principle of a grinding track algorithm, an orthogonal plane passes through the circle center of a grinding wheel, and a corresponding edge geometric shape function under the orthogonal plane can be obtained according to the edge shape of the cross section of the grinding wheel (measured by a measuring instrument or ground by a grinding wheel dresser);

and step 3: grinding wheel circle center track compensation calculation

Obtaining an actual grinding point coordinate by taking the nearest position of the edge of the grinding wheel and the rear cutter face as an actual grinding point, and combining a theoretical grinding point on an edge line to obtain a compensation vector of the circle center of the grinding wheel; because the grinding wheel axis vector is closely related to the back angle, in order to avoid the influence of compensation on the geometric parameters of the cutter, the grinding wheel axis vector is not changed in the compensation process, and only the circle center of the grinding wheel moves along the compensation vector;

for the flank grinding process, P is known_{s_o}Is a grinding wheel theoretical center point O under a movable coordinate system_gCoordinate of (A), P_bFor compensation vectors in the active coordinate system, M_o-wFor transformation of the active coordinate system into the rotation matrix of the workpiece coordinate system, T_o-wConverting the movable coordinate system into a translation matrix of a workpiece coordinate system to obtain a theoretical center point O of the grinding wheel under the workpiece coordinate system after compensation_gCoordinate P of_{s_w}Comprises the following steps:

P_{s_w}＝M_o-w·(P_{s_o}+P_b)+T_o-w(1)

under the movable coordinate system, the theoretical center point O of the grinding wheel before compensation_gCoordinate P of_{s_o}From the flank angle α_oAngle between grinding wheel end face and back cutter face₀(grinding lifting angle), grinding wheel diameter D expression, i.e.

The grinding point of the grinding wheel after compensation is the point closest to the edge line of the rear cutter face of the large end face of the grinding wheel, and a compensation vector P is set_bOn the axis X_oThe compensation amount in the direction is x_minCorresponding to the axis Z_oThe compensation amount in the direction is f (x)_min) Obtaining a compensation vectorP_bThe expression of (a) is: :

the arc-shaped edge is in a common edge shape, the edge of the grinding wheel is usually trimmed into an arc shape in actual production to prolong the service life, and the edge is approximately in the arc shape after a new grinding wheel is used for a period of time; let r be the radius of the edge fillet after the grinding wheel is worn, and the calculation result of the compensation vector can be obtained, as shown in table 1:

TABLE 1 Compensation vector solution demand parameters

In the object coordinate system O_w-X_wY_wZ_wSetting the grinding point P on the edge line relative to X_wThe initial deflection angle of the shaft being

substituting the formulas (4) and (5) into the formula (1) can obtain the compensated numerical control program machining coordinate, and reduce the machining error of the rear cutter face grinding through compensation adjustment of the original numerical control program.

Technical Field

The invention belongs to the technical field of integral end milling cutter processing, and particularly relates to a compensation method for grinding a rear cutter face of a peripheral tooth spiral blade by using a wear grinding wheel.

Background

In the grinding wheel track calculation process of the grinding process of the peripheral edge flank of the common end mill, the ideal measurement position of the diameter of the grinding wheel is on the end face of the grinding wheel, and the plane of the end face of the grinding wheel is taken as a calculation reference in the calculation. After the abrasive particles on the edge of the grinding wheel are worn and shed, the geometric morphology of the edge of the grinding wheel can be changed, so that the actual measurement position of the grinding wheel is not on the end face of the grinding wheel, the actual position and the theoretical position of the diameter measurement are not unified, and if the grinding track of the existing grinding wheel is still processed, a large size error can be generated by a cutter. Particularly, after a process parameter, namely a lifting angle of the grinding wheel, is introduced, the influence of geometric profile errors of the grinding wheel on the grinding precision is larger, so that the grinding track of the grinding wheel needs to be compensated to meet the actual processing requirement.

The research of the grinding wheel abrasion compensation technology mainly belongs to the fields of online control technology, mathematical optimization algorithm, control software development and the like. At present, compensation motion in a grinding process is researched a lot, however, grinding wheel compensation technology in an end mill grinding process is researched a little, and a compensation method is proposed mainly according to an existing method or a used machine tool and aiming at different working conditions or grinding wheels. Chinese patent document CN2017101219946 "a grinding wheel wear real-time compensation based on a numerical control system" calculates and real-time transforms the grinding wheel wear amount according to the change of the spindle motor current, transforms the grinding wheel wear amount in real time through a secondary development interface of the numerical control system on a compensation layer, and corrects the G code theoretical operation track point according to the real-time transformed grinding wheel wear amount, thereby realizing the grinding wheel wear real-time compensation.

The compensation research of the end mill grinding process only stays at the theoretical analysis or computer simulation stage, is not combined with the grinding track of the grinding wheel, can only be used for the condition that the initial state of the geometric structure of the grinding wheel is ideal, is inaccurate in compensation calculation of the grinding wheel with different initial abrasion loss, and cannot be applied to actual working conditions. Therefore, the research of the compensation method of the end mill grinding process needs to analyze the edge shape of the grinding wheel, introduce the edge shape of the grinding wheel into a grinding track, and fully combine the geometric parameters of the grinding wheel with an ideal grinding track to obtain the grinding track meeting the actual processing.

Disclosure of Invention

The invention aims to provide a compensation method for grinding a rear cutter face of a peripheral tooth spiral blade by using a worn grinding wheel, which aims to determine a compensation plane of a grinding process according to a grinding wheel structure, obtain a compensation vector of the circle center of the grinding wheel according to related parameters and perform compensation adjustment through an original numerical control program so as to reduce the machining error of grinding the rear cutter face.

The invention relates to a compensation method for grinding a rear cutter face of a peripheral tooth spiral blade by using a wear grinding wheel, which comprises the following steps:

step 1: compensated reference plane definition

Make the central axis of the cutter be Z_wThe center of a circle of the end surface of the revolving body of the shaft and the cutter is the origin O_wThe end face where the starting point of the blade is located is X_wO_wY_wPlane, establishing a workpiece coordinate system O_w-X_wY_wZ_w(ii) a In the workpiece coordinate system, a specified point on the spiral blade (i.e. a grinding point P on the blade line) is determined to correspond to three reference planes, namely base planes P_rCutting plane P_sTo the orthogonal plane P_oThe position of (a).

Since the three reference planes are spatial planes and the section lines of the flank face in the orthogonal plane are spatial line segments. To facilitate the description of the transversal model, a moving coordinate system O is established_o-X_oY_oZ_o. Origin O of the coordinate system_oCoincident with the grinding point P on the edge line, axis X_oOn the intersection of the basal plane and the orthogonal plane, axis Y_oOn the intersection of the cutting plane and the orthogonal plane, the axis Z_oAt the intersection of the cutting plane and the base plane.

Step 2: calculating the edge geometry function of the grinding wheel

In the actual use of the grinding wheel, the grinding process is complex and changeable, so the shape of the edge of the grinding wheel can be changed due to different working conditions. According to the design principle of a grinding track algorithm, the orthogonal plane passes through the circle center of the grinding wheel, and a corresponding edge geometric shape function under the orthogonal plane can be obtained according to the edge shape of the cross section of the grinding wheel (measured by a measuring instrument or ground by a grinding wheel dresser).

And step 3: grinding wheel circle center track compensation calculation

And (3) taking the nearest position of the edge of the grinding wheel and the rear cutter face as an actual grinding point, obtaining the coordinate of the actual grinding point, and combining the theoretical grinding point on the edge line to obtain the compensation vector of the circle center of the grinding wheel. Because the grinding wheel axis vector is closely related to the back angle, in order to avoid the influence of compensation on the geometric parameters of the cutter, the grinding wheel axis vector is not changed in the compensation process, and only the circle center of the grinding wheel moves along the compensation vector.

For the flank grinding process, P is known_{s_o}Is a grinding wheel theoretical center point O under a movable coordinate system_gCoordinate of (A), P_bFor compensation vectors in the active coordinate system, M_o-wFor transformation of the active coordinate system into the rotation matrix of the workpiece coordinate system, T_o-wTransforming the movable coordinate system into a translation matrix of the workpiece coordinate system to obtain a complementTheoretical center point O of grinding wheel under workpiece coordinate system after compensation_gCoordinate P of_{s_w}Comprises the following steps:

P_{s_w}＝M_o-w·(P_{s_o}+P_b)+T_o-w(1)

under the movable coordinate system, the theoretical center point O of the grinding wheel before compensation_gCoordinate P of_{s_o}From the flank angle α_oAngle between grinding wheel end face and back cutter face₀(grinding lifting angle), grinding wheel diameter D expression, i.e.

The grinding point of the grinding wheel after compensation is the point where the large end face of the grinding wheel is closest to the edge line of the rear cutter face, and a compensation vector P is set according to the point_bOn the axis X_oThe compensation amount in the direction is x_minCorresponding to the axis Z_oThe compensation amount in the direction is f (x)_min) Obtaining a compensation vector P_bThe expression of (a) is:

the arc-shaped edge is in a common edge shape, the edge of the grinding wheel is usually trimmed to be in an arc shape in actual production, the service life is prolonged, and after the new grinding wheel is used for a period of time, the edge is approximately in the arc shape. Let r be the radius of the edge fillet after the grinding wheel is worn, and the calculation result of the compensation vector can be obtained, as shown in table 1:

TABLE 1 Compensation vector solution demand parameters

In the object coordinate system O_w-X_wY_wZ_wSetting the grinding point P on the edge line relative to X_wThe initial deflection angle of the shaft being

(initial rotation angle of edge line) at Z_wThe axial movement distance is z, the radius of the blank bar stock is known to be R, the helical angle of the edge line of the cutter is known to be β, and M is obtained_o-w、T_o-wThe expression of the matrix is:

substituting the formulas (4) and (5) into the formula (1) can obtain the compensated numerical control program grinding coordinate, and reduce the machining error of the rear cutter face grinding through compensation adjustment of the original numerical control program.

The beneficial technical effects of the invention are as follows:

according to the invention, the compensation plane of the grinding process is determined according to the structure of the grinding wheel, the compensation vector of the circle center of the grinding wheel is obtained according to the parameters, and the machining error of the grinding of the rear cutter face is reduced by compensation adjustment of the original numerical control program.

Drawings

FIG. 1 is a schematic view of a coordinate system and a tool angle;

FIG. 2 is a compensation vector solving flow;

FIG. 3 is a comparison of grinding simulation, wherein (a) is the flank face before compensation and (b) is the flank face after compensation;

fig. 4 is a tool measurement view.

Detailed Description

The invention is described in further detail below with reference to the figures and the detailed description.

The invention discloses a compensation method for grinding a rear cutter face of a peripheral tooth spiral blade by using a wear grinding wheel, which comprises the following steps:

step 1: compensated reference plane definition

As shown in FIG. 1, the center axis of the tool is Z_wThe center of a circle of the end surface of the revolving body of the shaft and the cutter is the origin O_wThe end face where the starting point of the blade is located is X_wO_wY_wPlane, establishing a workpiece coordinate system O_w-X_wY_wZ_w. A base surface P corresponding to a certain designated point P on the spiral blade_rCutting plane P_sTo the orthogonal plane P_oIs shown in FIG. 1, P in FIG. 1_l-oIs a sectional line, and W is a helical edge line.

Since the three reference planes are spatial planes and the section lines of the flank face in the orthogonal plane are spatial line segments. To facilitate the description of the transversal model, a moving coordinate system O is established_o-X_oY_oZ_o. Origin O of the coordinate system_oCoincident with the grinding point P on the edge line, axis X_oOn the intersection of the basal plane and the orthogonal plane, axis Y_oOn the intersection of the cutting plane and the orthogonal plane, the axis Z_oAt the intersection of the cutting plane and the base plane.

Step 2: calculating the edge geometry function of the grinding wheel

In the actual use of the grinding wheel, the grinding process is complex and changeable, so the shape of the edge of the grinding wheel can be changed due to different working conditions. Fig. 2 shows a flow of implementing the compensation algorithm. According to the design principle of a grinding track algorithm, the orthogonal plane passes through the circle center of the grinding wheel, and a corresponding edge geometric shape function under the orthogonal plane can be obtained according to the edge shape of the cross section of the grinding wheel (measured by a measuring instrument or ground by a grinding wheel dresser).

And step 3: grinding wheel circle center compensation vector calculation

And (3) obtaining the actual grinding point coordinate by taking the nearest position of the edge and the rear cutter face as an actual grinding point, and combining the theoretical grinding point on the edge line to obtain the compensation vector of the circle center of the grinding wheel. Because the grinding wheel axis vector is closely related to the back angle, in order to avoid the influence of compensation on the geometric parameters of the cutter, the grinding wheel axis vector is not changed in the compensation process, and only the circle center of the grinding wheel moves along the compensation vector.

For the flank grinding process, P is known_{s_o}Is a grinding wheel theoretical center point O under a movable coordinate system_gCoordinate of (A), P_bFor compensation vectors in the active coordinate system, M_o-wFor transformation of the active coordinate system into the rotation matrix of the workpiece coordinate system, T_o-wConverting the movable coordinate system into a translation matrix of the workpiece coordinate system to obtain a compensated in-situ translation matrixCenter point O of a part coordinate system_gCoordinate P of_{s_w}Comprises the following steps:

P_{s_w}＝M_o-w·(P_{s_o}+P_b)+T_o-w(6)

under the movable coordinate system, the theoretical center point O of the grinding wheel before compensation_gCoordinate P of_{s_o}May be determined by the clearance angle α_oAngle between grinding wheel end face and back cutter face₀(grinding lifting angle), grinding wheel diameter D expression, i.e.

The grinding point of the grinding wheel after compensation is the point closest to the edge line of the rear cutter face of the large end face of the grinding wheel, and a compensation vector P is set_bOn the axis X_oThe compensation amount in the direction is x_minCorresponding to the axis Z_oThe compensation amount in the direction is f (x)_min) Obtaining a compensation vector P_bThe expression of (a) is:

rounded edges are a common edge shape. In actual production, the edge of the grinding wheel is usually trimmed into a circular arc shape, so that the service life is prolonged, and the edge can be similar to the circular arc shape after the new grinding wheel is used for a period of time. Let r be the edge fillet radius after the grinding wheel is worn, the calculation result of the compensation vector can be obtained, as shown in table 2.

TABLE 2 Compensation vector solution demand parameters

In the object coordinate system O_w-X_wY_wZ_wSetting the grinding point P on the edge line relative to X_wThe initial deflection angle of the shaft being(initial rotation angle of edge line) at Z_wAxial movementDistance z, radius of the blank bar is known as R, helix angle of the edge line of the cutter is known as β_o-w、T_o-wThe expression of the matrix is:

the compensated numerical control program grinding coordinate can be obtained by substituting equations (9) and (10) into equation (6).

Example applications

And (3) programming and realizing calculation by using MATLAB software, and performing simulation processing by using VERICUT software. VERICUT software can be set up processing simulation environment, can simulate the course of working of digit control machine tool to reduce cutter trial-manufacturing cost, guarantee processing safety.

For the machining link of the machine tool, a five-axis numerical control tool grinding machine of A-i5 series produced by a Dyege grinding machine is adopted, a numerical control system is Guangzhou numerical control, and the grinding machine has the positioning precision of 0.005mm and the repeated positioning precision of 0.003mm under the constant temperature condition. For the tool parameter detection link, a PG1000 tool detector produced by EURO-TECH company is used, the maximum repeated measurement error of the measuring instrument is 0.010mm (0.0005), and the requirement of actual production and processing is met.

According to the drawing of the actual cutter, the cutter in the table 3 is simulated and processed, the grinding wheel used is an 11V9 standard grinding wheel, the diameter of the grinding wheel is 99.96mm, and the round angle of the grinding wheel is 0.22 mm. In the grinding track calculation, the lift angle is uniformly set to be 2 degrees. Meanwhile, the compensation calculation is cancelled, and the comparison group is set to verify the compensation calculation. The simulation results are shown in FIG. 3

TABLE 3 tool parameters

And (3) carrying out actual machine tool machining by using the numerical control code subjected to simulation verification, and measuring various parameters of the machined tool by using the American PG1000 tool detector, wherein the parameters are shown as a tool measurement diagram in figure 4.

The tool was measured using a tool tester and the results of the tool parameter measurements are shown in table 4.

TABLE 4 measured parameters of the tool