Apparatus and method for determining the amount of abrasive particles working on a grinding wheel

Abstract

To provide an action abrasive grain determination device capable of determining an action point of action abrasive grains which contribute to grinding, out of abrasive grains existing on a ground plane, on the basis of a surface state of the ground plane of the grinding grind stone.SOLUTION: There is provided an action abrasive grain determination device comprising: an action point determining part 48 for determining action points of action abrasive grains, on the basis of a notch depth g / a of the abrasive grains per unit length calculated by a notch depth calculating part 44, and three-dimensional shape data acquired by a three-dimensional data acquiring part 46. Therefore the action point determining part 48 determines the action point of the action abrasive grains contributing to grinding, on the basis of the notch depth g / a of the abrasive grains per unit length and the three-dimensional shape data, therefore it is possible to determine only the action point of the action abrasive grains which contribute to grinding, out of the abrasive grains existing in a ground plane 18a, on the basis of a surface state of the ground plane 18a of the grinding grind stone 18. Therefore, evaluation accuracy of grinding performance of the grinding grind stone 18 can be secured.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to an active abrasive grain determination device and method for a grinding wheel, which determines active abrasive grains contributing to cutting among the abrasive grains protruding from the grinding surface of the grinding wheel based on the depth of cut of the abrasive grains per unit length and three-dimensional shape data.

Background Art

[0002] During grinding, the protrusion amount of the abrasive grains on the grinding surface affects grinding performance such as sharpness and grinding amount. When the protrusion amount is larger than the appropriate protrusion amount with respect to the abrasive grain diameter, there are more abrasive grain drop-offs and fractures, and the tool life cannot be obtained. When the protrusion amount is smaller than the appropriate protrusion amount with respect to the abrasive grain diameter, processing defects such as grinding burns occur due to insufficient chip pockets. In order to continuously obtain good grinding, it is desirable to evaluate the grinding performance of the grinding wheel from the three-dimensional shape of the grinding surface. For example, during dressing, in order to obtain a three-dimensional shape evaluated as having high grinding performance, the surface shape of the grinding surface is processed so that the evaluation value is within the target range.

[0003] On the other hand, in Patent Document 1, a method for measuring the protrusion amount of the abrasive grains of a grinding wheel is disclosed in order to evaluate whether the protrusion amount of the abrasive grains of the grinding wheel is the protrusion amount of the abrasive grains that stabilizes the grinding performance. In this method for measuring the protrusion amount of the abrasive grains, a surface shape acquisition unit that acquires the surface shape of the grinding surface, which is the outer peripheral surface of the grinding wheel, a surface shape unit that divides the grinding wheel in the radial direction at predetermined distances from the tip of the abrasive grain that protrudes most from the grinding surface, and only the abrasive grains, which are the cutting edges of the grinding wheel, the bond part bonded to the abrasive grains, or a plurality of abrasive grains and the bond that bonds the plurality of abrasive grains are extracted as the cutting edge region at each divided predetermined distance, and a region counting unit that counts the number of cutting edge regions, and a protrusion amount determination unit that determines the predetermined distance when the counted number of cutting edge regions changes from an increase to a decrease as the protrusion amount of the abrasive grains are provided.

Prior Art Documents

Patent Documents

[0004] [Patent Document 1] Japanese Patent Publication No. 2021-171887 [Overview of the Initiative] [Problems that the invention aims to solve]

[0005] According to the abrasive grain protrusion measurement method in Reference 1, the amount of abrasive grain protrusion is measured by the amount of bond being scraped off, distinct from the amount of abrasive grain protrusion due to natural pores. By managing this amount of abrasive grain protrusion, it is possible to suppress abrasive grain detachment and fracture, thereby stabilizing grinding performance.

[0006] Incidentally, the method for measuring the abrasive grain protrusion amount of a grinding wheel described in Patent Document 1 assumes that abrasive grains with the measured protrusion amount are the working abrasive grains that contribute to grinding. However, the determination of working abrasive grains does not take into account the difference in radial depth of the abrasive grain trajectories due to the difference in the spacing of the cutting edges of the working abrasive grains in the circumferential direction of the grinding wheel. As a result, abrasive grains whose maximum cutting depth is inside the tip trajectory of the abrasive grain adjacent to the upstream side are included as working abrasive grains that contribute to grinding, even though they do not contribute to grinding, which leads to the problem that the accuracy of evaluating the grinding performance of the grinding wheel cannot be sufficiently obtained.

[0007] The present invention was made against the above circumstances, and its objective is to provide a method and apparatus for determining the point of application of the active abrasive grains that contribute to grinding, among the abrasive grains present on the grinding surface of a grinding wheel, based on the surface condition of the grinding surface. [Means for solving the problem]

[0008] The gist of the first invention is (a) the uneven state of the grinding surface, which is the cylindrical outer surface of a grinding wheel that rotates around a rotational centerline. Three-dimensional shape data showingA grinding wheel working abrasive particle determination device for determining working abrasive particles that have a point of application that contacts the workpiece among the abrasive particles present on the grinding surface, comprising: (b) a cutting depth calculation unit that calculates the cutting depth of abrasive particles per unit length of the grinding surface from setting conditions including the peripheral speed of the grinding wheel, the amount of cutting of the workpiece, and the moving speed of the workpiece relative to the grinding wheel for the grinding process of the grinding wheel on the workpiece; and (c) a three-dimensional data of the grinding surface including the height data of the abrasive particles protruding from the grinding surface. The system includes (d) a three-dimensional shape data acquisition unit that acquires shape data, and an action point determination unit that determines, from (d) a diagonal line indicating the depth of the abrasive grains, which is a function of the length in the opposite direction to the grinding direction of the grinding surface, with the depth of the abrasive grains per unit length calculated by the depth of cut calculation unit as a proportionality constant, and the three-dimensional shape data acquired by the three-dimensional shape data acquisition unit, to be the working abrasive grains, which have an action point where the height of the abrasive grains is higher than the diagonal line.

[0009] The gist of the second invention is that in the first invention, (e) The distance in the height direction corresponding to the region higher than the diagonal line on the grinding direction side slope of the abrasive grain is, The maximum cutting depth of the abrasive grain at the point of application of the abrasive grain. as The system further includes a unit for calculating the maximum cutting depth.

[0010] The gist of the third invention is that, in the first or second invention, (f) the three-dimensional shape data acquisition unit acquires the three-dimensional shape data of the grinding surface in the width direction perpendicular to the grinding direction of the grinding surface based on the reflected light from the grinding surface This is a sequence of height data indicating the height of uneven surfaces. Equipped with an optical positioning meter that outputs two-dimensional data in a time series, The two-dimensional data is output as three-dimensional shape data, which includes the two-dimensional data for each circumferential distance of the grinding wheel. It is about that.

[0011] The gist of the fourth invention is that in any one of the first to third inventions, (g) the point of application determination unit, of the three-dimensional shape data, The three-dimensional shape data was obtained from two-dimensional data that was constructed in a time series. Point of action of the abrasive grains Number The cumulative value, A axis showing the cumulative value of the aforementioned points of action. The aforementioned Number of lines in 2D data This indicates Two dimensions relative to the axis Sequentially plotted on the coordinate system line Three-dimensional shape data after the point where the slope converges to a constant value. UsingThe objective is to determine the point of application of the abrasive particles.

[0012] The gist of the fifth invention is that, in the fourth invention, the point of application determination unit, among the three-dimensional shape data, The three-dimensional shape data was obtained from two-dimensional data that was constructed in a time series. Point of action of the abrasive grains Number The cumulative value, A axis showing the cumulative value of the aforementioned points of action. The aforementioned Number of lines in 2D data This indicates Two dimensions relative to the axis When plotted sequentially on a coordinate system, Movement of the number of lines Each section The slope of the regression line Three-dimensional shape data from the point where the correlation coefficient exceeds a predetermined threshold. Using The objective is to determine the point of application of the abrasive particles.

[0013] The gist of the sixth invention is (a) the uneven state of the grinding surface, which is the cylindrical outer surface of a grinding wheel that rotates around a rotational centerline. Three-dimensional shape data showing A method for determining the working abrasive grains of a grinding wheel using an electronic control device, for determining the working abrasive grains among the abrasive grains present on the grinding surface that have a point of application that contacts the workpiece, comprising: (b) a cutting depth calculation step for calculating the cutting depth of the abrasive grains per unit length of the grinding surface from setting conditions including the peripheral speed of the grinding wheel, the amount of cutting of the workpiece, and the moving speed of the workpiece relative to the grinding wheel for the grinding process of the grinding wheel on the workpiece; and (c) the grinding surface including height data of the abrasive grains protruding from the grinding surface (d) A three-dimensional shape data acquisition step is to acquire three-dimensional shape data of the grinding surface, and (d) a point of application determination step is to determine from the three-dimensional shape data acquired in the three-dimensional shape data acquisition step that abrasive grains having a point of application where their height is higher than the diagonal line are the working abrasive grains, based on a diagonal line indicating the depth of the abrasive grains, which is a function of the length in the direction opposite to the grinding direction of the grinding surface, with the depth of the abrasive grains per unit length calculated in the depth of application calculation step being the constant of proportion, and the point of application determination step is to determine that the working abrasive grains are the working abrasive grains. [Effects of the Invention]

[0014] According to the grinding wheel abrasive grain determination device of the first invention, the cutting depth is calculated by the cutting depth calculation unit. The aforementioned Depth of abrasive grain per unit length The diagonal lines indicate the depth of cut of the abrasive grains, which is a function of the length in the direction opposite to the grinding direction of the grinding surface, with proportionality constant set to .and, from the three-dimensional shape data acquired by the three-dimensional shape data acquisition unit, the The height of the abrasive grains becomes higher than the aforementioned diagonal line. points of action Those possessing the above characteristics are determined to be the abrasive particles. can be obtained. As a result , Ken the points of action of the active abrasive grains that solely contribute to grinding among the abrasive grains present on the grinding surface of the dressing grinding wheel can be determined from the state of the grinding surface of the dressing grinding wheel. Therefore, sufficient evaluation accuracy of the grinding performance of the grinding wheel can be obtained. unevenness

[0015] According to the active abrasive grain determination device for a grinding wheel of the second invention, The distance in the height direction corresponding to the region higher than the diagonal line on the grinding direction side slope of the abrasive grain is, a maximum depth of cut calculation unit that calculates the maximum depth of cut of the active abrasive grain at the point of action of the active abrasive grain is provided. As a result, in the maximum depth of cut calculation unit, since the maximum depth of cut of the active abrasive grain at the point of action of the active abrasive grain is calculated, as sufficient evaluation accuracy of the grinding performance of the grinding wheel can be obtained based on the point of action of the active abrasive grain that contributes to grinding and the maximum depth of cut of the active abrasive grain. The height is highest above the aforementioned diagonal line.

[0016] According to the active abrasive grain determination device for a grinding wheel of the third invention, the three-dimensional shape data acquisition unit includes an optical position measuring instrument that outputs two-dimensional data in the width direction perpendicular to the grinding direction of the grinding surface based on the reflected light from the grinding surface in a time series. This is a sequence of height data indicating the height of uneven surfaces. As a result, when the grinding wheel is a grinding wheel lathe, three-dimensional shape data of the grinding surface, which is the outer peripheral surface of the grinding wheel lathe, can be acquired while the grinding wheel lathe is rotating. The two-dimensional data is output as three-dimensional shape data, which includes the two-dimensional data for each circumferential distance of the grinding wheel.

[0017] According to the active abrasive grain determination device of the fourth invention, the point of action determination unit sequentially plots the cumulative value of the points of action of the active abrasive grains among the three-dimensional shape data on the The three-dimensional shape data was obtained from two-dimensional data that was constructed in a time series. points of action of the active abrasive grains Number and, after the point where the slope converges to a constant value in the A axis showing the cumulative value of the aforementioned points of action. coordinates indicating Number of lines in 2D data plots, the three-dimensional shape data Two dimensions relative to the axis line Using ​​​​​The point of application of the abrasive grains is determined. By doing so, the three-dimensional shape data of the initial grinding section is removed, and the cumulative value of the total number of application points of the abrasive grains in the grinding direction is sequentially plotted on the coordinate system indicating the grinding direction of the grinding surface. line The point of application of the abrasive grain is determined from the three-dimensional shape data of the stable section after the point where the slope converges to a constant value.

[0018] According to the abrasive particle determination device of the fifth invention, the point of application determination unit determines, from the three-dimensional shape data, The three-dimensional shape data was obtained from two-dimensional data that was constructed in a time series. Point of action of the abrasive grains Number The cumulative value, A axis showing the cumulative value of the aforementioned points of action. The aforementioned Number of lines in 2D data This indicates Two dimensions relative to the axis When plotted sequentially on a coordinate system, Movement of the number of lines Each section The slope of the regression line Three-dimensional shape data from the point where the correlation coefficient exceeds a predetermined threshold. Using The point of application of the abrasive grain is determined. As a result, the three-dimensional shape data of the initial grinding section is removed, and the constant Movement of the number of lines Each section Slope of the regression line The point of application of the abrasive grain is determined from the three-dimensional shape data of the stable interval after the point in which the correlation coefficient exceeds a predetermined threshold.

[0019] The sixth invention , the grinding wheel controlled by an electronic control device Abrasive particle determination method According to the above, the cut depth calculation step was calculated The aforementioned Depth of abrasive grain per unit length The diagonal lines indicate the depth of cut of the abrasive grains, which is a function of the length in the direction opposite to the grinding direction of the grinding surface, with proportionality constant set to . And, from the three-dimensional shape data obtained by the three-dimensional shape data acquisition process, The height of the abrasive grains becomes higher than the aforementioned diagonal line. Point of application Those having the above-mentioned abrasive particles judgement difference This will result in , Ken grinding surface of grinding wheel unevenness From the state, it is possible to determine the point of application of the active abrasive grains that contribute exclusively to grinding among the abrasive grains present on the grinding surface. Therefore, sufficient accuracy can be obtained in evaluating the grinding performance of the grinding wheel. [Brief explanation of the drawing]

[0020] [Figure 1]This figure illustrates the configuration of a surface grinding machine to which the abrasive grain determination device according to one embodiment of the present invention is applied. [Figure 2] Figure 1 is a schematic diagram illustrating the abrasive grains and points of application on the grinding surface of the grinding wheel. [Figure 3] This figure shows a map indicating the positions corresponding to the three-dimensional shape data, where the maximum cutting depth at the point of application, calculated by the point of application determination unit and the maximum cutting depth calculation unit in Figure 1, is located. [Figure 4] This figure shows the cumulative number of points of application and correlation coefficient with respect to the data lines for the three-dimensional shape data acquired by the three-dimensional data acquisition unit shown in Figure 1. [Figure 5] This figure shows a histogram of the cutting depth g of the abrasive grains for a grinding wheel used under the same grinding test conditions as in Figure 4. [Figure 6] This flowchart explains the key operating parts of the electronic control unit of the surface grinding machine shown in Figure 1, along with the flowchart in Figure 7. [Figure 7] Figure 1 shows a flowchart illustrating the key operating parts of the electronic control unit of the surface grinding machine, along with the flowchart in Figure 6. [Modes for carrying out the invention]

[0021] Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings. Note that in the following embodiment, the drawings illustrate the essential parts related to the invention, and the dimensions and shapes are not necessarily depicted accurately. [Examples]

[0022] Figure 1 is a front view showing a surface grinding machine 12 to which an abrasive particle determination device 10 according to one embodiment of the present invention is applied. The surface grinding machine 12 includes a base 14, a grinding wheel drive box 20 which is provided so as to be movable in the vertical direction along a guide rod 16 erected on the base 14 and supports a grinding wheel 18 so as to be rotatable around a rotation centerline CL and houses a grinding wheel drive motor (not shown) that rotates the grinding wheel 18, a vertical drive motor 24 which rotates a screw shaft 22 that moves the grinding wheel drive box 20 in the vertical direction, and workpiece moving motors 30 and 32 which move a workpiece mounting table 28 on the base 14 in a direction perpendicular to the rotation centerline CL and in a direction parallel to the rotation centerline CL, respectively.

[0023] The grinding wheel drive box 20 is equipped with an optical positioning meter 34 that non-contactively detects the three-dimensional shape of the grinding surface 18a, which is the cylindrical outer surface of the rotating grinding wheel 18. The positioning meter 34 is supported via a bracket 36 that allows it to move in a direction parallel to the rotation centerline CL. For example, a laser two-dimensional displacement meter is preferably used as the positioning meter 34. The positioning meter 34 outputs three-dimensional shape data that shows the two-dimensional data in the width direction perpendicular to the grinding direction of the grinding surface 18a in a time series, based on the reflected light from the grinding surface 18a. The three-dimensional shape data shows the irregularities of the grinding surface 18a of the grinding wheel 18.

[0024] The electronic control unit 40 is configured to select a surface grinding control mode for performing surface grinding of the workpiece 26, and an application point determination control mode for determining (detecting) the application point of abrasive grains on the grinding surface 18a of the grinding wheel 18, according to a control mode switching operation using the input device 42.

[0025] When the surface grinding control mode is selected, the electronic control unit 40 stores the setting conditions for surface grinding that have been set by the input operation from the input device 42, and rotates the grinding wheel 18 at a set peripheral speed (m / min) according to the setting conditions for surface grinding, and uses the vertical drive motor 24 to set the depth of cut (mm) of the workpiece 26, and uses the workpiece moving motors 30 and 32 to move the workpiece 26 on the mounting table 28 horizontally at a set table moving speed (m / min) relative to the grinding wheel 18, thereby performing surface grinding on the upper surface of the workpiece 26.

[0026] When the point of application determination control mode is selected, the electronic control device 40 functionally includes a cutting depth calculation unit 44, a three-dimensional data acquisition unit 46, a point of application determination unit 48, and a maximum cutting depth calculation unit 50, and displays the numerical value and map of the point of application determined on the grinding surface 18a, as well as the maximum cutting depth gmax, etc., on the display device 52.

[0027] The depth of cut calculation unit 44 corresponds to the depth of cut calculation process and calculates the depth of cut of abrasive grains per unit length g / a from the following equation (1) based on the setting conditions for surface grinding of the grinding wheel 18 on the workpiece 26. In equation (1), g is the depth of cut of the abrasive grains (mm), a is the spacing between the cutting edges of the abrasive grains (mm), v is the speed of the workpiece 26 (m / min), V is the peripheral speed of the grinding wheel 18 (m / min), D is the diameter of the grinding wheel 18 (mm), and t is the depth of cut of the grinding wheel 18 (mm).

[0028] g / a=2×(v / V)×√(t / D) ···(1)

[0029] The three-dimensional data acquisition unit 46 corresponds to the three-dimensional shape data acquisition process and acquires and stores three-dimensional shape data indicating the unevenness of the grinding surface 18a from the signal output from the positioning meter 34. This three-dimensional shape data includes line data of height data Z1, Z2, Z3, ... Zn, which indicates the height of the unevenness in the width (thickness) direction of the grinding surface 18a, for each circumferential distance Δa of the grinding wheel 18.

[0030] The point of application determination unit 48 corresponds to the working abrasive grain determination process, and calculates the point of application of the working abrasive grains within the grinding surface 18a from the cutting depth calculation unit 44, which calculates the cutting depth of the abrasive grains per unit length g / a from the setting conditions for planar machining, and the three-dimensional shape data. For example, in the schematic diagram of the grinding surface 18a in Figure 2, assuming that multiple abrasive grains GP1, GP2, GP3, and GP4 are located along the x-direction opposite to the grinding direction of the grinding surface 18a, and when the diagonal line L1, which indicates the cutting depth of the abrasive grains per unit length g / a, is drawn from the vertex of the abrasive grain GP1 as the trajectory of the tip of the abrasive grain GP1, the z-direction height (vertex) of the second abrasive grain GP2 and the third abrasive grain GP3 is located below the diagonal line L1, so the second abrasive grain GP2 and the third abrasive grain GP3 do not contribute to grinding and do not function as working abrasive grains. In contrast, the height (vertex) of the fourth abrasive grain GP4 in the z direction is higher than the diagonal line L1 which indicates the cutting depth of the abrasive grain per unit length g / a. Therefore, the point of application determination unit 48 determines that the fourth abrasive grain GP4 is the active abrasive grain that contributes to grinding, and the portion of the slope of the abrasive grain GP4 that intersects with the diagonal line L1 (a local region of the slope) is determined to be the point of application. An active abrasive grain is an abrasive grain that has a point of application.

[0031] The maximum cutting depth calculation unit 50 corresponds to the maximum cutting depth calculation process. For each working abrasive grain, the distance in the z-direction corresponding to the region where the points of application of action are connected on the grinding direction side slope of the abrasive grain determined as the working abrasive grain by the point of application determination unit 48 (in Figure 2, the fourth abrasive grain GP4) is calculated as the maximum cutting depth gmax.

[0032] Figure 3 shows a map for each cell illustrating the numerical data indicating the determination result of the working abrasive grain and the maximum cutting depth gmax, calculated by the point of application determination unit 48 and the maximum cutting depth calculation unit 50, schematically corresponding to the working abrasive grains. In Figure 3, the x-direction indicates the relative movement direction of the workpiece 26 with respect to the grinding surface 18a, i.e., the direction opposite to the grinding direction of the grinding surface 18a with respect to the workpiece 26, and the y-direction indicates the axial width direction parallel to the rotation centerline CL of the grinding surface 18a. Within the xy plane, cell regions not involved in grinding are marked with an "n", cell regions involved in grinding are marked with a "-", and the cell region corresponding to the vertex of the working abrasive grain shows the "numerical value indicating the maximum cutting depth gmax (μm)".

[0033] The point of application determination unit 48 determines the point of application of the abrasive grains based on the three-dimensional shape data acquired by the three-dimensional data acquisition unit 46, specifically the three-dimensional shape data obtained from the point after which the slope of the cumulative value (cumulative number of points of application) Ncp in the direction opposite to the grinding direction x of the total number of points of application of the abrasive grains in the width direction of the grinding surface 18a converges to a certain value when plotted sequentially on a coordinate system indicating the grinding direction of the grinding surface 18a.

[0034] Furthermore, the point of application determination unit 48 determines the point of application of the abrasive grains based on the three-dimensional shape data acquired by the three-dimensional data acquisition unit 46. The cumulative value Ncp of the total points of application of the abrasive grains in the width direction, i.e., the y direction, of the grinding surface 18a in the direction opposite to the grinding direction Ncp, is plotted sequentially on a coordinate system that shows the direction opposite to the grinding direction Ncp of the grinding surface 18a. The three-dimensional shape data obtained from the three-dimensional shape data acquired by the three-dimensional data acquisition unit 46 is determined based on the three-dimensional shape data after the point where the correlation coefficient for each certain interval exceeds a threshold, for example, 4000, which is set in advance to determine a stable and reliable data interval.

[0035] Figure 4 shows the confidence interval of the three-dimensional shape data obtained by the inventor under the following grinding test conditions. (Grinding test conditions) Grinding method: Surface grinding Cutting depth t: 0.02mm Grinding wheel: Electroplated CB230PA5 Grinding wheel peripheral speed: 2000 m / min Workpiece feed rate: 20 m / min Grinding wheel diameter: 205 mm

[0036] Figure 4 shows a two-dimensional coordinate system with the horizontal axis representing the number of line data points and the vertical axis representing the cumulative number of points of action and the correlation coefficient. The curve representing the cumulative number of points of action is shown as a dashed line, and the curve representing the correlation coefficient is shown as a solid line. The curve representing the cumulative number of points of action converges to a constant value when the number of line data points exceeds 1000, and the curve representing the correlation coefficient to the slope of the regression line exceeds a predetermined threshold when the cumulative number of points of action exceeds 40000, or when the number of line data points exceeds 4700.

[0037] Figure 5 shows a histogram of the cutting depth (μm) of the grinding wheel in a two-dimensional coordinate system with the horizontal axis representing the cutting depth (μm) and the vertical axis representing the frequency, obtained by the inventor under the above grinding test conditions.

[0038] The aforementioned abrasive particle determination device 10 includes a positioning meter 34, a cutting depth calculation unit 44, a three-dimensional data acquisition unit 46, a point of application determination unit 48, and a maximum cutting depth calculation unit 50.

[0039] Figures 6 and 7 show flowcharts illustrating the main parts of the control operation of the electronic control device 40 when the point of application determination control mode is selected. In Figure 6, first, in step S1 (the steps will be omitted hereafter) corresponding to the depth of cut calculation unit 44, the depth of cut of abrasive grains per unit length g / a is calculated, for example, using equation (1) from the cutting conditions set in advance by the operation of the input device 42.

[0040] Next, in S2, S3, and S4 corresponding to the three-dimensional data acquisition unit 46, line data including height data Z1, Z2, Z3, ··· Zn indicating the uneven height in the width (thickness) direction of the grinding surface 18a, which constitutes the three-dimensional shape data, is sequentially read. First, in S2, the first line data is read, and the data Z1, Z2, Z3, ··· Zn included in the line data is read. Next, in S3, a set of acting point candidates P (P1 = Z1, P2 = Z2, P3 = Z3, ··· Pn = Zn) is set corresponding to the height data Z1, Z2, Z3, ··· Zn included in the line data. Then, in S4, the data Z1, Z2, Z3, ··· Zn of the next adjacent line data in the x direction is read.

[0041] Next, S5, S6 - S7, and S9 - S15 corresponding to the acting point determination unit 48 are executed. First, in S5, the cumulative distance pitch at (= at + Δa), which is the moving distance from the reading start position of the newly read line data, is calculated. Next, in S6, the grinding grain trajectory lowest point L (= Z - g / a × at) is calculated for each peak indicated by the height data Z (Z1, Z2, Z3, ··· Zn) of the initially read line data as a determination value for determining whether the height of the grinding grain at the position at of the newly read line data is an acting point contributing to grinding. Next, in S7, it is determined whether the height data Z (Z1, Z2, Z3, ··· Zn) of the newly read line data is not less than the grinding grain trajectory lowest point L.

[0042] In S7, if it is determined that the height data Z of the newly read line data does not exceed the grinding grain trajectory lowest point L (Z < L), S8 and subsequent steps are executed. In S8, it is determined whether the determination result of the previously read line data is a determination that the height data Z of the line data is not less than the grinding grain trajectory lowest point L (Z ≧ L). If the determination in S8 is negative (Z < L), S16 described later is executed. If it is determined in S16 that there is a next line data, S4 and subsequent steps are executed, but if it is determined in S16 that there is no next line data, this routine is terminated.

[0043] If the judgment in S8 is affirmed (Z≧L), the maximum abrasive grain cutting depth gmax (=(g / a)×at×N) is calculated in S17, which corresponds to the maximum cutting depth calculation unit 50. In the following S17, the contents of the number of consecutive point of action judgments N are reset to zero, and then the steps from S11 onwards, described below, are executed.

[0044] In S7, if it is determined that the height data Z of the newly loaded line data is greater than or equal to the lowest point L of the abrasive grain trajectory (Z≧L), then in S9, it is determined to be the point of application, and the corresponding position in the height data Z of the newly loaded line data is set and stored as the point of application of the abrasive grain.

[0045] In S10, the number of consecutive point of application determinations N (=N+1) is calculated based on the point of application determination in S9. In the following S11, the cumulative number of points of application Pn (=Pn+Pl) is calculated. Pl is the number of point of application determination positions in the newly read line data.

[0046] In S12, it is determined whether the slope (increase rate) of the cumulative number of points of action Pn, which increases as new line data is read, has converged to a constant slope, and whether the number of times cumulative height data (line data) has been acquired has exceeded the first confidence data acquisition judgment value (number of lines for correlation coefficient calculation, e.g., 4000 lines) which has been experimentally set in advance. If the judgment in S12 is negative, the steps from S4 onwards described above are executed, but if it is positive, the steps from S13 onwards are executed.

[0047] In S13, the correlation coefficient of the slope of the regression line in a moving interval of 4000 line widths of line data is calculated. In S14, it is determined whether the value calculated in S13 exceeds a pre-set threshold, such as the second confidence data acquisition judgment value (for example, a correlation coefficient of 0.96). If the determination in S14 is negative, the steps from S4 onwards described above are executed. However, if it is positive, in S15, the point of application determined in S7 and stored in S9, and the maximum abrasive grain cutting depth gmax calculated in S17 are output as the point of application determination result. This point of application determination result includes, for example, the map shown in Figure 3.

[0048] Then, in S16, it is determined whether or not there is data for the next line. If the determination in S16 is negative, the execution of S4 and below is repeated, but if the determination in S16 is positive, this routine is terminated.

[0049] As described above, the working abrasive grain determination device 10 of this embodiment is equipped with a point of application determination unit 48 that determines the point of application of the working abrasive grains from the cutting depth g / a per unit length calculated by the cutting depth calculation unit 44 and the three-dimensional shape data acquired by the three-dimensional data acquisition unit 46. As a result, the point of application determination unit 48 determines the point of application of the working abrasive grains that contribute to grinding from the cutting depth g / a per unit length and the three-dimensional shape data, so it is possible to determine the point of application of the working abrasive grains that contribute exclusively to grinding from the surface state of the grinding surface 18a of the grinding wheel 18.Therefore, sufficient accuracy in evaluating the grinding performance of the grinding wheel 18 can be obtained.

[0050] Furthermore, the working abrasive grain determination device 10 of this embodiment is equipped with a maximum cutting depth calculation unit 50 that calculates the maximum cutting depth of the working abrasive grain at the point of application of the working abrasive grain. As a result, the maximum cutting depth gmax of the working abrasive grain at the point of application of the working abrasive grain is calculated by the maximum cutting depth gmax of the working abrasive grain, and sufficient accuracy in evaluating the grinding performance of the grinding wheel 18 can be obtained by using the point of application of the working abrasive grain that contributes to grinding and the maximum cutting depth gmax of the working abrasive grain.

[0051] Furthermore, according to the working abrasive grain determination device 10 of this embodiment, the three-dimensional data acquisition unit 46 includes an optical positioning meter that outputs two-dimensional data of the grinding surface in the width direction perpendicular to the grinding direction of the grinding surface 18a in a time series based on reflected light from the grinding surface 18a. This makes it possible to acquire three-dimensional shape data of the grinding surface 18a, which is the outer surface of the grinding wheel, while the grinding wheel is rotating, when the grinding wheel 18 is a grinding wheel.

[0052] Furthermore, according to the working abrasive grain determination device 10 of this embodiment, the application point determination unit 48 determines the application point of the working abrasive grains based on the three-dimensional shape data from the point after which the slope of the cumulative value of the total application points of the working abrasive grains in the width direction of the grinding surface 18a, which is sequentially plotted on a coordinate system indicating the grinding direction of the grinding surface 18a, converges to a constant value. As a result, unstable three-dimensional shape data in the initial grinding section is removed, and the application point of the working abrasive grains is determined from the three-dimensional shape data of the stable section from the point after which the slope of the cumulative value of the total application points of the working abrasive grains in the grinding direction, which is sequentially plotted on a coordinate system indicating the grinding direction of the grinding surface 18a, converges to a constant value.

[0053] According to the working abrasive grain determination device 10 of this embodiment, the application point determination unit 48 determines the application point of the working abrasive grain based on the three-dimensional shape data after the point where the correlation coefficient for each certain interval exceeds a preset threshold, obtained by sequentially plotting the cumulative value of the total application points of the working abrasive grains in the width direction of the grinding surface 18a on a coordinate system indicating the grinding direction of the grinding surface 18a. As a result, unstable three-dimensional shape data in the initial grinding section is removed, and the application point of the working abrasive grain is determined from the stable three-dimensional shape data after the point where the correlation coefficient for each certain interval exceeds a preset threshold.

[0054] The method for determining the working abrasive grains of this embodiment includes a point of application determination step that determines the point of application of the working abrasive grains based on the cutting depth of the abrasive grains per unit length calculated by the cutting depth calculation step and the three-dimensional shape data acquired by the three-dimensional shape data acquisition step. As a result, the point of application determination step determines the point of application of the working abrasive grains that contribute to grinding based on the cutting depth of the abrasive grains per unit length calculated by the cutting depth calculation unit and the three-dimensional shape data acquired by the three-dimensional shape data acquisition step. Therefore, it is possible to determine the point of application of the working abrasive grains that contribute exclusively to grinding from among the abrasive grains present on the grinding surface of the grinding wheel, based on the surface condition of the grinding surface. Consequently, sufficient accuracy in evaluating the grinding performance of the grinding wheel 18 can be obtained.

[0055] Although one embodiment of the present invention has been described above with reference to the drawings, the present invention can also be applied to other embodiments.

[0056] For example, in the above-described embodiment, the working abrasive particle determination device 10 applied to the surface grinding machine 12 was explained, but the working abrasive particle determination device 10 can also be applied to grinding machines such as cylindrical grinding machines and internal grinding machines. In the case of a cylindrical grinding machine, the following equation (2) is used in the cutting depth calculation unit 44, and in the case of an internal grinding machine, the following equation (3) is used in the cutting depth calculation unit 44.

[0057] g / a=2×(v / V)×√(1 / D+1 / d)×√t ···(2) g / a=2×(v / V)×√(1 / D-1 / d)×√t ···(3)

[0058] Furthermore, the abrasive particle determination device 10 in the above-described embodiment was equipped with a maximum cutting depth calculation unit 50. However, since the grinding performance of the grinding wheel 18 can be evaluated by the distribution of points of action within the grinding surface 18a alone, it is not necessary to include a maximum cutting depth calculation unit 50.

[0059] Furthermore, the grinding wheel 18 may be a vitrified grinding wheel in which abrasive grains are bonded by a vitrified bond, a resinoid grinding wheel in which abrasive grains are bonded by a resinoid bond, an electroplated grinding wheel in which abrasive grains are bonded by an electroplated metal, or the like.

[0060] Furthermore, the abrasive grains of the grinding wheel 18 may be any of the following: fused alumina abrasive grains, silicon carbide abrasive grains, diamond abrasive grains, CBN abrasive grains, etc.

[0061] It should be noted that the above is merely one embodiment of the present invention, and various modifications can be made to the present invention without departing from its spirit. [Explanation of Symbols]

[0062] 10: Abrasive particle size determination device 12: Surface grinding machine 18: Grinding Wheel 18a: Grinding surface 40: Electronic control unit 44: Cutting depth calculation unit 46: Three-dimensional data acquisition unit 48: Point of action determination section 50: Maximum cutting depth calculation unit

Claims

1. A grinding wheel working abrasive particle determination device for determining working abrasive particles that have a point of action in contact with the workpiece, based on three-dimensional shape data showing the uneven state of the grinding surface, which is the cylindrical outer surface of the grinding wheel rotating around a rotation centerline, A cutting depth calculation unit calculates the cutting depth of abrasive grains per unit length of the grinding surface from setting conditions including the peripheral speed of the grinding wheel, the amount of cutting of the workpiece, and the movement speed of the workpiece relative to the grinding wheel, for the grinding process of the grinding wheel on the workpiece. A three-dimensional shape data acquisition unit acquires three-dimensional shape data of the grinding surface, including height data of the abrasive grains protruding from the grinding surface. The system includes a diagonal line indicating the depth of abrasive grains, which is a function of the length in the direction opposite to the grinding direction of the grinding surface, with the depth of abrasive grains per unit length calculated by the depth of cut calculation unit as a proportionality constant, and an action point determination unit that determines, from the three-dimensional shape data acquired by the three-dimensional shape data acquisition unit, to be the active abrasive grains, which have an action point where the height of the abrasive grains is higher than the diagonal line. A device for determining the abrasive particles working on a grinding wheel, characterized by the above features.

2. The unit further includes a maximum cutting depth calculation unit that calculates the distance in the height direction corresponding to the region higher than the diagonal line on the grinding direction side slope of the working abrasive grain as the maximum cutting depth of the working abrasive grain at the point of application of the working abrasive grain. A device for determining the working abrasive grains of a grinding wheel according to feature 1.

3. The three-dimensional shape data acquisition unit includes an optical positioning meter that outputs two-dimensional data in a time series, which is a sequence of height data indicating the height of the unevenness of the grinding surface in the width direction perpendicular to the grinding direction of the grinding surface, based on the reflected light from the grinding surface, and outputs three-dimensional shape data that includes the two-dimensional data for each distance in the circumferential direction of the grinding wheel. A device for determining the abrasive particles working on a grinding wheel according to feature 1 or 2.

4. The point of application determination unit determines the point of application of the abrasive grain by using the three-dimensional shape data from which the cumulative number of points of application of the abrasive grain obtained from the two-dimensional data that constitutes the three-dimensional shape data in a time series converges to a certain value. This is done using the three-dimensional shape data from the point onward where the slope of the line plotted sequentially on a two-dimensional coordinate system between an axis indicating the cumulative number of points of application and an axis indicating the number of lines in the two-dimensional data converges to a certain value. A device for determining the working abrasive grains of a grinding wheel according to any one of the features 1 to 3.

5. The point of application determination unit determines the point of application of the abrasive grain by using the three-dimensional shape data from the point onward where the correlation coefficient of the slope of the regression line for each moving interval of a certain number of lines exceeds a preset threshold, obtained by sequentially plotting the cumulative number of points of application of the abrasive grain obtained from the two-dimensional data that constitutes the three-dimensional shape data in a time series on a two-dimensional coordinate system between an axis indicating the cumulative number of points of application and an axis indicating the number of lines in the two-dimensional data. A device for determining the abrasive particles working on a grinding wheel, as described in feature 4.

6. A method for determining the active abrasive grains of a grinding wheel using an electronic control device, wherein the active abrasive grains present on the grinding surface have a point of contact with the workpiece, based on three-dimensional shape data showing the unevenness of the grinding surface, which is the cylindrical outer surface of the grinding wheel rotating around a rotation centerline, A cutting depth calculation step, which calculates the cutting depth of abrasive grains per unit length of the grinding surface from setting conditions including the peripheral speed of the grinding wheel, the amount of cutting of the workpiece, and the movement speed of the workpiece relative to the grinding wheel, A three-dimensional shape data acquisition step is performed to acquire three-dimensional shape data of the grinding surface, including height data of the abrasive grains protruding from the grinding surface. The process includes a diagonal line indicating the depth of abrasive grains, which is a function of the length in the direction opposite to the grinding direction of the grinding surface, with the depth of abrasive grains per unit length calculated in the above-mentioned depth of cut calculation step as a proportionality constant, and an action point determination step in which, from the three-dimensional shape data acquired in the above-mentioned three-dimensional shape data acquisition step, the abrasive grains having an action point where their height is higher than the diagonal line are determined to be the working abrasive grains. A method for determining the active abrasive grains of a grinding wheel, characterized by the following features.

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