Surface grinder and workpiece grinding method

Abstract

To efficiently grind a surface of a workpiece.SOLUTION: A surface grinder for grinding a surface of a workpiece W by relatively grind-feeding a rotation grindstone 15 along the surface of the workpiece W is provided with adjustment means for adjusting a grind feeding speed according to a grind allowance caused by the rotation whetstone 15. The adjustment means makes the grind feeding speed slower in a place where a grinding allowance is large, and the grind feeding speed faster in a place where the grinding allowance is small.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a surface grinding machine for grinding the surface of, for example, a plate-shaped workpiece with a rotary grinding wheel, and a method for grinding a workpiece. [Background technology]

[0002] Patent Document 1 discloses a technology that bypasses grinding of areas that do not need to be machined based on CAD data. This path allows the tool to be fed at high speed through areas that do not need to be machined, achieving highly efficient grinding. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent Publication No. 2021-168031 Summary of the Invention [Problem to be solved by the invention]

[0004] In the above-mentioned Patent Document 1, when performing grinding, it is necessary to prepare CAD data of the workpiece, which clearly indicates the processing area and the non-processing area. In other words, when performing grinding with high speed feed, it is necessary to create CAD data of the workpiece, which is cumbersome. [Means for solving the problem]

[0005] The present invention is characterized in that a surface grinding machine in which a rotating grinding wheel is fed relatively along the surface of a workpiece to grind the surface of the workpiece is provided with an adjustment means for adjusting the grinding feed speed depending on the size of the grinding allowance D to be removed by the rotating grinding wheel.

[0006] The present invention is also characterized in that in a method for grinding a workpiece, in which a rotating grinding wheel is fed relatively along the surface of the workpiece to grind the surface of the workpiece, the grinding feed speed is adjusted depending on the amount of grinding allowance D to be removed by the rotating grinding wheel.

[0007] Therefore, in the present invention, the feed speed of the workpiece is adjusted according to the grinding allowance D, so that the feed speed of the workpiece can be increased in the portion where the grinding amount is small. As a result, the total time required for grinding can be shortened. Effect of the Invention

[0008] According to the present invention, it is possible to efficiently grind the surface of a workpiece while feeding at a high speed, without preparing CAD data for the workpiece. [Brief description of the drawings]

[0009] [Figure 1] FIG. 1 is a front view of a surface grinding machine used in the first to second and fourth embodiments. [Diagram 2] FIG. 4 is a block diagram showing the electrical configuration of the surface grinding machine. [Diagram 3] FIG. 4 is a diagram showing an exaggerated depiction of the shape of the workpiece surface and a feed rate in the first embodiment. [Figure 4] FIG. [Diagram 5] (a) is a plan view showing the measurement state of the workpiece, and (b) is a front view of the same. [Figure 6] 4 is a flowchart showing the operation of the first and second embodiments. [Figure 7] 7 is a flowchart showing a subroutine of S6 in the flowchart of FIG. 6. [Figure 8] FIG. 11 is a diagram showing an exaggerated depiction of the shape of the work surface and the feed rate in the second embodiment. [Figure 9] FIG. 10 is a diagram showing an exaggerated depiction of the shape of the workpiece surface and the feed rate in a modified example of the second embodiment. [Figure 10]FIG. 11 is a front view of a surface grinding machine used in a third embodiment. [Figure 11] FIG. 4 is a block diagram showing the electrical configuration of the surface grinding machine. [Figure 12] FIG. [Figure 13] FIG. 13 is a front view of a curved workpiece according to a fourth embodiment. [Figure 14] This figure also shows the feed rate and exaggerates the unevenness of the workpiece surface. [Figure 15] FIG. 11 is a diagram showing the state after grinding of one surface of the workpiece has been completed, and also showing the feed rate. [Figure 16] 13(a) to (d) are perspective views showing the processing steps for the workpiece. [Figure 17] 6(a) to 6(f) are side views showing the processing process for the workpiece. [Figure 18] 13 is a flowchart showing the operation of the fourth embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] (First embodiment) A surface grinding machine and a workpiece grinding method according to a first embodiment of the present invention will now be described with reference to FIGS. 1 to 7. FIG.

[0011] <Configuration of surface grinder> As shown in Fig. 1, a movable table 10 is supported on the upper surface of a frame 11 of the surface grinding machine so as to be movable back and forth in the X-axis direction, which is the grinding feed direction in Fig. 1. A chuck table 12, the upper surface of which serves as a workpiece support surface, is fixed to the movable table 10. The chuck table 12 is made of a magnetic chuck. A coil (not shown) of a magnet 28 (see Fig. 2) of the chuck table 12 is excited by passing current through it, whereby the workpiece W is magnetically attracted to the upper surface of the chuck table 12.

[0012] A column 13 is supported on the upper surface of the frame 11 so as to be movable back and forth in the Z-axis direction in FIG. 1. The movable table 10 may be disposed at a fixed position, and the column 13 may be movable back and forth in the X-axis direction. A lifting body 14 is supported on the front surface of the column 13 so as to be movable back and forth in the Y-axis direction in FIG. 1, i.e., so as to be liftable and lowerable, and a rotary grindstone 15 is supported on this lifting body 14. The upper surface of the workpiece W placed on the chuck table 12 is ground by the rotation of this rotary grindstone 15. Here, the movement of the rotary grindstone 15 in the Y-axis direction is the cutting direction for the workpiece W. Grinding includes polishing.

[0013] A measuring sensor 17 as measuring means having a touch probe 16 is provided on the lift body 14 so as to be positionable at a measuring position below the lift body 14 and at a standby position above the lift body 14. The control device 21 and the measurement sensor 17 shown in Fig. 2 constitute an adjustment means. The control device 21 is electrically connected to a motor 22 which reciprocates the chuck table 12 in the X-axis direction via the movable stage 10, a motor 23 which reciprocates the column 13 in the Z-axis direction, and a motor 24 which raises and lowers the lifting body 14 in the Y-axis direction. The control device 21 is electrically connected to a motor 25 which rotates the grindstone 15. The control device 21 is also electrically connected to a coil (not shown) of a magnet 28 which magnetizes the chuck table 12. The control device 21 is further electrically connected to the measurement sensor 17 and a keyboard 31 which serves as an operation unit for manually inputting various data.

[0014] The control device 21 includes a central processing unit 26 and a storage unit 27. The storage unit 27 stores various types of temporary data, and also stores data of the programs shown in Fig. 6 and Fig. 7 for operating the surface grinding machine of this embodiment.

[0015] (Workpiece grinding) Next, in the operation of the first embodiment, a case where the grinding of the workpiece W is performed in one movement process (one pass) will be described. Here, one pass refers to a process in which the grinding wheel 15 grinds the top surface of the workpiece W by moving (forward) once in the X-axis direction relative to the workpiece W. That is, the flowcharts in Figs. 6 and 7 are executed by the program stored in the storage unit 27 of the control device 21 under the control of the central processing unit 26. In grinding the workpiece W, the grinding wheel 15 is fed horizontally relative to the top surface of the workpiece W on the chuck table 12 while changing its position in the Z-axis direction. At this time, as described above, the grinding wheel 15 grinds the top surface of the workpiece W in the forward process parallel to the chuck table 12 and the top surface, that is, horizontally and linearly. The feeding of the grinding wheel 15 in the X-axis direction is executed by the movement of the chuck table 12.

[0016] In step (hereinafter, S) 1 shown in FIG. 6, the operator inputs various grinding condition data from the keyboard 31 as the grinding conditions. That is, the operator inputs the material of the workpiece W, the specifications of the grindstone 15, the peripheral speed of the grindstone 15 during grinding, and the finished thickness T of the workpiece W shown in FIG. 3. The operator also inputs the amount of cut in the Y-axis direction of the grindstone 15 in one grinding process, that is, the cut depth, as the grinding allowance D, which is a grinding condition. The operator also inputs the maximum feed rate of the grindstone 15 in the X-axis direction. This maximum feed rate is the feed rate of the grindstone 15 in the X-axis direction when grinding of the workpiece W is not performed by the grindstone 15, that is, the feed rate for air cutting. Naturally, the feed rate for air cutting is set to a speed considerably faster than the feed rate associated with grinding.

[0017] Then, the operator inputs the grinding position for each grinding step in the Z-axis direction of the grinding wheel 15, i.e., the grinding pitch in the Z-axis direction. This grinding pitch is equal to or slightly narrower than the thickness of the grinding wheel 15.

[0018] The above data on the grinding conditions is stored in the storage unit 27. Therefore, the grinding conditions, that is, the processing data, are set in the storage unit 27. Then, the central processing unit 26 adjusts the feed speed of the grinding wheel 15 in accordance with the grinding allowance D. Here, the grinding allowance D refers to the thickness in the Y-axis direction that is cut off by the grinding wheel 15 to obtain the finished thickness T of the workpiece W, in other words, to cut out the finished surface K of the workpiece W. The control device 21 controls the grinding feed speed of the grinding wheel 15 in the X-axis direction so as to be changed according to the size of the grinding allowance D. The smaller the grinding allowance D, the faster the grinding speed.

[0019] Shortly before or after S1, in S2, the shape of the upper surface of the workpiece W on the table 12 is measured. As shown in Fig. 4, Fig. 5(a) and Fig. 5(b), in this measurement, the touch probe 16 of the measurement sensor 17 in the lowered position, which is the measurement position, comes into contact with the top surface of the workpiece W. Then, by moving the table 12 in the X-axis direction and the column 13 in the Z-axis direction, the touch probe 16 moves on the top surface of the workpiece W in the X-axis direction and the Z-axis direction, as shown by the two-dot chain line in Fig. 5(a). This movement is performed vertically and horizontally many times, changing the position at a narrow pitch. Therefore, as a measurement result, the positions of the unevenness on the top surface of the workpiece W, the shape of the unevenness, and the height of the unevenness are detected. Data related to the detected unevenness is stored in the memory unit 27. Note that the measurement by the touch probe 16 may be performed by moving only in one of the X-axis direction and the Z-axis direction.

[0020] In S3, the height of the upper surface S of the workpiece W including the unevenness is calculated from the position of the finishing surface K when the finishing thickness T of the workpiece W is obtained. As a result, the grinding allowance D of the workpiece W is calculated. In addition, in S3, the vertical dimension from the apex of the highest convexity to the finishing surface K of the workpiece W, that is, the largest grinding allowance D, is calculated. Then, based on the grinding allowance D and the cutting amount of the grinding wheel 15 in the Y-axis direction in one grinding process, the number of feeds, which is the number of grinding in the X-axis direction until the finishing surface K is obtained, is calculated. These calculated data are stored in the memory unit 27 and set as grinding conditions. Note that in FIG. 3, the illustration of the unevenness of the lower surface of the workpiece W is omitted, and only the unevenness of the upper surface is exaggerated, and in the following explanation of the flowchart, the case of grinding the upper surface of the workpiece W will be explained. The same applies to FIGS. 8, 9, 14, and 15.

[0021] In S4, the feed speed of the grinding wheel 15 in each part of the workpiece W in the X-axis direction is calculated according to the size of the grinding allowance D. The calculated data is set in the storage unit 27, and is set as the grinding conditions.

[0022] In S5, grinding of the workpiece W is carried out. Fig. 6 shows the grinding subroutine of S5. In S11 of Fig. 6, the grinding wheel 15 is located at a home position at the height of the grinding feed outside the workpiece W, away from the workpiece W. Subsequently, the grinding wheel 15 is moved relatively toward the workpiece W at the air cutting speed, which is the fastest feed speed, by the movement of the chuck table 12 in the X-axis direction. Then, when it is determined in S12 that the grinding wheel 15 has reached the grinding area of ​​the workpiece W, in S13, the feed speed of the grinding wheel 15 in the X-axis direction is reduced to the feed speed set in S4 corresponding to the grinding allowance D.

[0023] That is, as shown in the diagram of FIG. 3, the feed rate of the grinding wheel 15 is adjusted so as to correspond to the size of the grinding allowance D on the upper side from the finishing surface K, which is the upper surface position for obtaining the finishing thickness T of the workpiece W. When the grinding allowance D is large, the feed rate is slowed down so as to correspond to the size of the grinding allowance D. Conversely, when the grinding allowance D is small, the feed rate is fastened. Therefore, as is clear from the feed rate change curve Cu of FIG. 3, the change in the feed rate of the grinding wheel 15 is inversely proportional to the size of the grinding allowance D. In this way, when the grinding allowance D is small, the grinding wheel 15 performs grinding in one pass, which is one grinding process, in the X-axis direction, and the one-pass grinding is performed by changing the position in the Z-axis direction. Therefore, the grinding allowance D of the entire upper surface of the workpiece W is ground, and the finishing surface K is cut out. Then, when the feeding process for cutting out the finish surface K is completed, the grindstone 15 rises in S14, and returns to the home position at the fastest speed, which is air cutting, in S15. In this manner, the process in S5 in FIG. 6 ends.

[0024] In S6 of Fig. 6, it is determined whether the number of grinding operations set in S3 has been completed. If the number of grinding operations has been completed, the grinding operation is stopped. If grinding of the entire grinding allowance D has not been completed in one grinding process (one pass), the process returns to S5 and the grinding feed is repeated (multiple passes).

[0025] That is, in the above-mentioned process, grinding is completed by the rotary grindstone 15 performing one operation (one pass) in the X-axis direction. On the other hand, when the grinding allowance D is large, or when the cutting amount of the rotary grindstone 15 in the Y-axis direction is small, it is necessary to repeat the process in the X-axis direction multiple times. That is, when the multi-pass process is set in S3, the grinding process is calculated in S5 of FIG. 5 until the thickness T is obtained. Then, in each process, the feed speed in the X-axis direction is adjusted. That is, since a low convex part is exposed in the grinding area every time grinding is performed, the number of convex parts to be ground may vary. Therefore, in such a case, the air cut area with the maximum feed speed also varies. Then, in S6, after the subroutine shown in FIG. 7 is executed, it is determined whether the number of multi-pass processes calculated in S3 has been completed. If not, the process returns to S6. If completed, the grinding operation is stopped.

[0026] In this manner, the finished surface K is formed. Thereafter, grinding of the back surface of the workpiece W is carried out in a similar manner. Effects of the First Embodiment The first embodiment has the following advantages.

[0027] (1) Since the grinding feed speed is adjusted according to the size of the grinding allowance D, the feed speed of the grinding wheel 15 is faster where the grinding allowance D is small. And since the grinding feed speed is the fastest in the portion where grinding is not performed, it is possible to improve the processing efficiency as much as possible. Therefore, the total processing time required for grinding the workpiece W can be shortened.

[0028] (2) The grinding feed speed is adjusted according to the grinding allowance D. In other words, where the amount of grinding is large, the grinding speed is slowed down. This eliminates grinding unevenness and allows for a uniform, high-precision ground surface to be obtained.

[0029] Second embodiment Next, a second embodiment of the present invention will be described with reference to Figures 6 to 9. In this embodiment shown in Figure 9, a finishing surface K is cut out that is not linear but curved.

[0030] <When the top surface of the workpiece is flat before grinding> In this embodiment, a case will be described where the top surface of the workpiece W has a flat shape. In S1 of Fig. 6, the operator inputs data on the shape of the top surface S of the workpiece W as grinding conditions, together with data similar to those in the first embodiment, such as the material of the workpiece W, from the keyboard 31. In addition, in S1, the operator inputs data on the shape of the finished surface K, which has a curved shape, as grinding conditions.

[0031] Then, the program from S2 onwards is executed, and in S2, the position of the top surface S of the workpiece W is measured for confirmation. In S3, the grinding allowance D corresponding to the shape of the finished surface K and the cutting depth in the Y-axis direction of the grinding wheel 15 for grinding off the grinding allowance D are set. Also, in S3, the number of grinding feeds corresponding to the size of the grinding allowance D is set. Then, in S4, the feed speed for each variation in the grinding allowance D is set.

[0032] That is, as shown in the diagram of Fig. 8, the feed speed of the grinding wheel 15 is adjusted so as to correspond to the size of the grinding allowance D from the upper surface S of the workpiece W to the finished surface K. When the grinding allowance D is large, the feed speed is slowed down so as to correspond to the size of the grinding allowance D. Conversely, when the grinding allowance D is small, the feed speed is increased. Therefore, as is clear from the feed speed change curve Cu in Fig. 8, the feed speed change curve Cu of the grinding wheel 15 is proportional to the shape of the finished surface K.

[0033] Then, after grinding of the workpiece W is performed in S5, it is determined in S5 whether the number of grinding cycles has ended. In the case of one-pass, grinding ends through S7. In the case of multi-pass, when the set number of grinding cycles has ended, grinding ends through S7.

[0034] <When the workpiece has unevenness on its top surface before grinding> The workpiece W shown in FIG. 9 has unevenness on its upper surface, similar to the workpiece W shown in FIG. 3, before grinding. When forming a finished surface K of a curved shape as shown in FIG. 8 for such a workpiece W, the programs shown in FIG. 6 and FIG. 7 are executed. Then, in S1, data of the finished surface K is set, and then in S2, the shape of the upper surface S of the workpiece W is measured. Next, based on the shape of the upper surface S measured in S3 and the shape of the finished surface K, the grinding allowance D and the number of grinding feeds are set. Then, in S4, the grinding feed rate of the grinding wheel 15 is set. The feed rate change curve Cu shows a trajectory that follows the value obtained by subtracting the value of the height of the finished surface K from the value of the height of the upper surface S of the workpiece W at each position in the X-axis direction. Then, in S5 to S7, grinding is performed according to the grinding allowance D and the number of grinding feeds set in the same manner as described above.

[0035] (Effects of the second embodiment) Even if the finished surface K has a curved shape, the feed rate in the X-axis direction can be adjusted according to the size of the grinding allowance D. Therefore, the workpiece W can be ground efficiently and with high precision.

[0036] Third embodiment Next, a third embodiment of the present invention will be described with reference to FIGS. In the third embodiment, the upper surface of a circular plate-shaped workpiece W is ground. To this end, the chuck table 32 is rotated about a central axis Ce extending in the Y-axis direction by a motor 33 shown in Fig. 11. Therefore, the workpiece W is rotated about the central axis Ce. This rotation of the workpiece W becomes the processing feed of the rotary grindstone 15.

[0037] 12, the rotary grindstone 15 is positioned such that its rotation surface (a surface parallel to the X-axis and Y-axis) is tangent to the direction of rotation of the workpiece W, i.e., along the X-axis direction. As the column 13 moves in the Z-axis direction, the rotary grindstone 15 is moved in the radial direction of the workpiece W.

[0038] 12, the touch probe 16 of the measurement sensor 17 detects an annular area on the top surface of the workpiece W on the chuck table 12 as the chuck table 12 rotates. Furthermore, the touch probe 16 moves along the radial direction of the workpiece W as the column 13 moves in the Z-axis direction. Therefore, data on the unevenness on the top surface of the workpiece W is stored as being present in an annular area centered on the center of the workpiece W. Therefore, height data on the magnitude of the grinding allowance D for grinding the unevenness on the top surface of the workpiece W is also stored on the annular area of ​​the rotating grinding wheel 15.

[0039] 12, as the workpiece W rotates about the central axis Ce, the rotary grindstone 15 is fed relatively in the direction tangent to the rotational direction of the workpiece W without moving in the X-axis direction, thereby grinding away the irregularities. Every time the workpiece W rotates once, the rotary grindstone 15 is moved in the Z-axis direction, and the grinding position is changed.

[0040] In the third embodiment, since the rotary grindstone 15 is never positioned at the end of the workpiece W, the determination as to whether the grinding region has ended is made based on whether the workpiece W has completed 360-degree rotation.

[0041] (Fourth embodiment) Next, a fourth embodiment of the present invention will be described with reference to FIGS. In the fourth embodiment, as shown in Fig. 13, a flat surface is formed on a workpiece W that is curved in its natural state, to form a plate P (see Fig. 17(f)) that is not curved in its natural state. The configuration of the surface grinding machine is the same as that of the first embodiment.

[0042] First, in S21, similarly to the first embodiment, various grinding conditions are input from the keyboard 31. Here, in the fourth embodiment, a thickness T1 after finishing a finishing surface K of one side of the workpiece W shown in Fig. 14 and Fig. 15, and a final thickness T2 which is a target workpiece thickness after finishing a finishing surface K of the other side, which is the thickness of the plate P, are input.

[0043] 16(a) and 17(a), the curved workpiece W is placed in its natural state on the non-magnetized chuck table 12. In this case, the workpiece W is placed so that the convexly bulging portion faces upward. Here, the bulging upper surface S of the workpiece W is the front surface W1, and the opposite surface is the back surface W2.

[0044] 16(a), the surface W1 located on the upper side of the workpiece W is measured by the touch probe 16 of the measurement sensor 17. In this measurement, the height of the entire surface from the upper surface of the chuck table 12 and the height of the irregularities on the surface W1, i.e., the size of the grinding allowance D, are measured as in the first embodiment. The measured data is stored in the memory unit 27 of the control device 21.

[0045] Next, in S23, the position data is subjected to spline interpolation, and a virtual curve C that follows the entire curved shape of the workpiece W is set. Next, in S24, electricity is applied to the magnet 28 to magnetize the chuck table 12. As a result, the workpiece W is attracted to the upper surface of the chuck table 12 by magnetic force. In this attracted state, as shown in Fig. 16(b) and Fig. 17(b), the workpiece W is deformed and tightly adheres to the upper surface of the chuck table 12 without any gaps. Therefore, the curvature of the workpiece W is eliminated, and this state is maintained.

[0046] Then, in S25, as shown in FIG. 16(b), the height position of the workpiece W from the top surface of the chuck table 12 and the position and height of the unevenness which is the grinding allowance D are measured by the touch probe 16, and are stored in the memory unit 27.

[0047] Next, the same processes as S3 to S5 in Fig. 6 are executed. That is, in S26, the height of the convex portion relative to the position of the finished surface K, which is the grinding surface after grinding, in the unevenness of the upper surface of the workpiece W, that is, the grinding allowance D, is calculated. Also, the detected convex portion is eliminated by grinding according to the grinding of the predetermined grinding allowance D, and the number of feeds of the grinding wheel 15 in the X-axis direction, which is the number of grinding operations required to obtain the required thickness T1 of the workpiece W, is calculated. However, in the fourth embodiment, the cut position in the Y-axis direction, that is, the position of the grinding allowance D, changes continuously along the virtual curve C so that the virtual curve C appears. Therefore, the height of the convex portion and the position of the bottom of the concave portion are calculated according to the shape of the virtual curve C.

[0048] In S27, the feed speed of the grindstone 15 required for grinding the convex portion in each grinding round is set. Then, in S28, as is clear from Fig. 14, grinding processing and judgment are performed at a feed rate corresponding to the actual grinding allowance D similar to S5 in Fig. 6. In this case, as shown in Fig. 16(c) and Fig. 17(c), grinding is performed so that the surface of the virtual curve C appears and the irregularities are removed. Thus, grinding of the surface W1 of the workpiece W is completed. At this stage, the workpiece W having the thickness T1 is formed at the center of the workpiece W in the X-axis direction.

[0049] Then, in S30 after the judgment in S29, the current to the magnet 28 is cut off and the magnetic attraction of the workpiece W is released, and the workpiece W is restored to its natural shape by its own elasticity. In this case, since the front surface W1 has been ground into an inverted curved shape, the curved shape of the front surface W1 in the natural state disappears, as shown in Fig. 16(d) and Fig. 17(d). Therefore, the front surface W1 becomes a flat surface parallel to the upper surface of the chuck table 12, but the back surface W2 becomes curved.

[0050] 15 and 17(e), in S31, the workpiece W is turned over manually or the like, and placed on the upper surface of the chuck table 12 with the back surface W2 of the workpiece W facing up. Then, in S32, the chuck table 12 is magnetized. Due to this magnetization, the workpiece W is attracted to the chuck table 12, and the front surface W1, which has been ground flat, is brought into close contact with the upper surface of the chuck table 12 and fixed with the back surface W2 of the workpiece W facing up.

[0051] In this state, in S33 and S34, the back surface W2 of the workpiece W is ground flat in the same manner as in S5 and S6 in Fig. 6 so that the workpiece W becomes a plate P with a required thickness T2. Therefore, as is clear from Fig. 15, grinding is performed such that the feed speed is slower in the higher parts of the back surface W2 and faster in the lower parts. As a result, a plate P with a uniform thickness is formed as a whole, as shown in Fig. 17(f). Thereafter, in S35, the chuck table 12 is demagnetized, so that the plate P can be removed from the chuck table 12.

[0052] In this manner, a plate P can be obtained which is not curved, that is, is smooth and flat, has the desired flat finishing surface K, and has the required thickness. Effects of the Fourth Embodiment Therefore, in the fourth embodiment, the following effects can be obtained.

[0053] (1) When measuring the surface W1, a gently continuing imaginary curve C can be obtained. As a result, by grinding the workpiece W so that the imaginary curve C appears, a smooth flat surface can be obtained.

[0054] (2) After the shape conforming to the imaginary curve C appears, the flat front surface W1 is used as a reference, and the back surface W2 opposite the front surface W1 is ground while the workpiece W is in an undeformed state. This allows the workpiece W to be machined with high precision into, for example, a plate P of uniform thickness from which distortion has been removed.

[0055] (Example of change) Next, modifications of the present invention other than the above-described embodiment will be described. In the fourth embodiment, the back surface W2 is ground at an angle different from that of the front surface W1. In other words, the back surface W2 and the front surface W1 are not parallel to each other, but are inclined relative to each other.

[0056] The surface W1 of the workpiece W is measured at a plurality of measurement points, and the surface shape is determined by spline interpolation of the data of the measurement points. In the fourth embodiment, grinding of the surface W1 of the workpiece W is performed in a process different from the setting of the virtual curve C. For example, in a device that does not have a rotating grinding wheel 15, the virtual curve C is set, data of the virtual curve C is transferred to a surface grinding machine, the surface grinding machine is operated according to the data, and the workpiece W is ground by the surface grinding machine.

[0057] In the fourth embodiment, the order of measuring the surface W1 in its natural state and measuring it in its flattened state is reversed. The surface of the workpiece W is measured using a sensor other than the contact type using the touch probe 16, for example a sensor using a laser beam.

[0058] In the first, second and fourth embodiments, the workpiece W is ground by reciprocating the grindstone 15 in the X-axis direction. [Explanation of symbols]

[0059] 15...Rotary grindstone 17…Measuring sensor 21...Control device 26...Central processing unit 27...Storage section D…Grinding allowance K…Finished surface W…Work W1…Surface

Claims

1. A surface grinding machine for grinding a surface of a workpiece by relatively feeding a rotating grinding wheel along the surface of the workpiece, The surface grinding machine is provided with an adjustment means for adjusting the grinding feed speed in accordance with the size of the grinding allowance D to be removed by the rotating grindstone.

2. 2. The surface grinding machine according to claim 1, wherein the adjusting means measures the surface shape of the workpiece prior to the grinding, and, according to the measurement results, makes the grinding feed speed faster in areas where the grinding allowance D of the workpiece is small than in areas where the grinding allowance D is large.

3. 3. The surface grinding machine according to claim 2, wherein said adjusting means makes the grinding feed speed fastest in the portion where said grinding is not performed.

4. 2. The surface grinding machine according to claim 1, wherein said adjusting means measures the shape of the surface of said workpiece and then sets a target shape of the finished surface after grinding is completed.

5. 2. The surface grinding machine according to claim 1, wherein the adjusting means measures the shape of the surface of the workpiece and then sets a target thickness of the workpiece to be measured after the grinding is completed.

6. 1. A method for grinding a workpiece, comprising the steps of: relatively feeding a rotating grinding wheel along a surface of the workpiece to grind the surface of the workpiece, the method comprising the steps of: A method for grinding a workpiece, the grinding feed speed being adjusted according to the size of the grinding allowance D to be removed by the rotating grindstone.

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