Grinding machine

Abstract

To easily perform product inspections. [Solution] The grinding machine 10 processes the workpiece W with a rotating grinding wheel 11 by changing the relative position of the grinding wheel support 12 and the table 14 using a position changing device 20. The direction in which the rotating grinding wheel 11 is pressed against the processing surface of the workpiece W is defined as the first direction, and the direction in which the relative position is changed during processing of the workpiece W is defined as the second direction. The grinding machine 10 has a first distance sensor 35, a second distance sensor 36, and a shape estimation unit. The first distance sensor 35 detects a first displacement amount of the rotating grinding wheel 11 relative to the grinding wheel support 12 in the first direction during processing of the workpiece W. The second distance sensor 36 detects a second displacement amount of the rotating grinding wheel 11 relative to the grinding wheel support 12 in the second direction during processing of the workpiece W. The shape estimation unit estimates the shape of the processing surface of the workpiece W based on the relative position, the first displacement amount, and the second displacement amount.

Description

Technical Field

[0001] The present invention relates to a grinding machine.

Background Art

[0002] Conventionally, a grinding machine that performs grinding processing is known (see Patent Document 1). The grinding machine described in Patent Document 1 includes a rotating grindstone, a table to which a workpiece is fixed, and a position changing device that changes the relative position of the rotating grindstone and the table. In this grinding machine, grinding of the workpiece by the rotating grindstone is performed through the operation of the position changing device.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] When performing grinding processing with a grinding machine, product inspection is carried out, such as measuring the dimensions of each part of the workpiece (or product) during or after processing. The work involved in such inspection is time-consuming and complicated.

Means for Solving the Problems

[0005] A grinding machine for solving the above problems includes a grinding wheel support section that rotatably supports a rotating grinding wheel, a fixing section for which a workpiece is fixed, and a position changing device that changes the relative position of the grinding wheel support section and the fixing section, wherein the grinding machine processes the workpiece with the rotating grinding wheel through the change of the relative position by the position changing device, and when the direction in which the rotating grinding wheel is pressed against the workpiece surface is defined as the first direction, and the direction in which the relative position is changed during the processing of the workpiece is defined as the second direction, the grinding machine includes a first detection section that detects a first displacement amount of the rotating grinding wheel relative to the grinding wheel support section in the first direction during the processing of the workpiece, a second detection section that detects a second displacement amount of the rotating grinding wheel relative to the grinding wheel support section in the second direction during the processing of the workpiece, and a shape estimation section that estimates the shape of the processed surface based on the relative position, the first displacement amount, and the second displacement amount.

[0006] The positional coordinates of each part of the workpiece's machining surface are determined by the machining point during machining. The machining point is basically determined by the relative positions of the grinding wheel support and the fixed part. Furthermore, the relative positions of the grinding wheel support and the rotating grinding wheel during workpiece machining are not constant, but shift slightly depending on the force exerted on the rotating grinding wheel from the workpiece at the machining point. As the machining point shifts along with these relative positional shifts, the effect becomes apparent in the shape of the workpiece's machining surface.

[0007] According to the above configuration, the basic position of each part of the workpiece machining surface can be determined based on the relative positions of the grinding wheel support and the fixing part. Furthermore, the amount of displacement of the rotating grinding wheel relative to the grinding wheel support during workpiece machining (specifically, the first displacement and the second displacement) can be used as the amount of positional deviation from the basic position. Therefore, according to the above configuration, the actual positional coordinates of each part of the workpiece machining surface can be estimated by determining the positional coordinates shifted by the amount of positional deviation from the basic position. Then, the shape of the workpiece machining surface can be estimated and understood from these actual positional coordinates of each part of the workpiece machining surface.

[0008] Thus, with the above configuration, during the machining of a workpiece by the grinding machine, the relative position, first displacement, and second displacement can be obtained by the equipment installed in the grinding machine, thereby estimating the shape of the machined surface of the workpiece. Therefore, special operations such as temporarily stopping the machining of the workpiece for inspection, temporarily removing the workpiece (or product) from the grinding machine, or preparing separate inspection equipment become unnecessary, making product inspection easy to perform. [Effects of the Invention]

[0009] According to the present invention, product inspection can be easily performed. [Brief explanation of the drawing]

[0010] [Figure 1] Figure 1 is a side view of a grinding machine according to one embodiment. [Figure 2] Figure 2 is a block diagram showing the electrical circuit structure of the grinding machine. [Figure 3] Figure 3 is a plan view of the workpiece. [Figure 4] Figure 4 is a side cross-sectional view showing the structure of the first distance sensor, the second distance sensor, and their surroundings. [Figure 5] Figure 5 is a side cross-sectional view showing the structure of the first distance sensor, the second distance sensor, and their surroundings. [Figure 6] Figure 6 is a table showing an example of tabular data. [Figure 7] Figure 7 is a schematic diagram showing an example of image data. [Figure 8] Figure 8 is a schematic diagram showing an example of the relative positional relationship between the workpiece and the rotating grinding wheel during machining. [Figure 9] Figure 9 is a flowchart showing the execution procedure for the shape data creation process. [Modes for carrying out the invention]

[0011] The following description of a grinding machine 10 according to one embodiment will be given with reference to Figures 1 to 9. As shown in Figure 1, the grinding machine 10 is a numerically controlled (NC) surface grinding device that processes the surface of the workpiece W into a flat surface using a rotating grinding wheel 11.

[0012] The rotating grinding wheel 11 is formed in a roughly disc shape. The rotating grinding wheel 11 is supported by the grinding wheel support 12 in a rotatable state. More specifically, the rotating grinding wheel 11 is connected to the rotating shaft 111. The rotating shaft 111 is supported by the grinding wheel support 12 in a rotatable state by an oil hydrostatic bearing. The rotating shaft 111 of the rotating grinding wheel 11 extends in the horizontal direction, more specifically in the left-right direction in Figure 1 (hereinafter referred to as the Z direction). In this embodiment, the Z direction corresponds to the third direction.

[0013] The rotating grinding wheel 11 and the grinding wheel support 12 are movable relative to the base 13 in the vertical direction (hereinafter referred to as the Y direction) and the horizontal direction (more specifically, the Z direction). In the grinding machine 10, the surface of the workpiece W is ground by rotating the grinding wheel 11 and bringing it into contact with the workpiece W.

[0014] The grinding machine 10 has a table 14 as a fixing part to which the workpiece W is fixed. The table 14 is movable relative to the base 13 in a direction perpendicular to the Z and Y directions in the horizontal direction, specifically in the depth direction (hereinafter referred to as the X direction) in Figure 1. In the grinding machine 10, the workpiece W on the table 14 can be moved by moving the table 14 in the X direction. This makes it possible to change the relative position of the rotating grinding wheel 11 and the workpiece W in the X direction. In this embodiment, the X direction corresponds to a second direction, which is the direction in which the relative position PM of the table 14 and the rotating grinding wheel 11 is changed during the machining of the workpiece W.

[0015] In the grinding machine 10, the relative positions of the rotating grinding wheel 11 in the X direction, Y direction, and Z direction between the rotating grinding wheel 11 and the workpiece W can be changed individually by moving the rotating grinding wheel 11 in the Y direction or Z direction, or by moving the table 14 in the X direction.

[0016] <Position changing device 20> As shown in FIG. 1 and FIG. 2, a grinding machine 10 includes a position changing device 20 that changes a relative position PM of a table 14 and a rotating grinding wheel 11. The position changing device 20 changes a relative position PA of the rotating grinding wheel 11 and the table 14 by changing a relative position PM of a grinding wheel support portion 12 and the table 14. The position changing device 20 is constituted by an X-axis drive unit 21, a Y-axis drive unit 22, and a Z-axis drive unit 23.

[0017] The X-axis drive unit 21 is a device for moving the table 14 in the X direction relative to a base 13. The X-axis drive unit 21 includes a ball screw mechanism, a servo motor, and the like. The X-direction position of the table 14 relative to the base 13 is controlled through operation control of the X-axis drive unit 21.

[0018] The Y-axis drive unit 22 is a device that moves the rotating grinding wheel 11 and the grinding wheel support portion 12 in the Y direction relative to the base 13. The Y-axis drive unit 22 includes a ball screw mechanism, a servo motor, and the like. The Y-direction position of the rotating grinding wheel 11 relative to the base 13 is controlled through operation control of the Y-axis drive unit 22. In the present embodiment, the Y direction corresponds to a first direction that is a direction for pressing the rotating grinding wheel 11 against a machined surface of a workpiece W.

[0019] The Z-axis drive unit 23 is a device for moving the rotating grinding wheel 11 and the grinding wheel support portion 12 in the Z direction relative to the base 13. The Z-axis drive unit 23 includes a ball screw mechanism, a servo motor, and the like. The Z-direction position of the rotating grinding wheel 11 relative to the base 13 is controlled through operation control of the Z-axis drive unit 23.

[0020] The grinding machine 10 includes a grinding wheel drive unit 24 for rotationally driving the rotating grinding wheel 11. The grinding wheel drive unit 24 has an electric motor 241 connected to a rotation shaft 111 of the rotating grinding wheel 11. In operation control of the grinding wheel drive unit 24 (specifically, the electric motor 241), the rotating grinding wheel 11 is basically rotated at a constant speed. Note that a speed matching the machining conditions is set as the rotation speed of the rotating grinding wheel 11 on the basis of the machining conditions input to the grinding machine 10.

[0021] As shown in Figure 3, the machined surface of the workpiece W is divided into multiple machining regions in the Z direction (in the example shown in the figure, four machining regions AR1 to AR4). The machined surface of the workpiece W is then machined (grinded) by changing the relative position PM of the grinding wheel support 12 and the table 14 in the X direction, and this process is performed sequentially for each of the multiple machining regions while changing the relative position PM in the Z direction, thereby machining the entire surface of the workpiece W.

[0022] <Electronic control unit 30> As shown in Figure 2, the grinding machine 10 is equipped with an electronic control unit 30. The electronic control unit 30 performs various controls related to the operation of the grinding machine 10. A position change device 20 and a grinding wheel drive unit 24 are connected to the electronic control unit 30. The electronic control unit 30 has a processing unit (PU), ROM, RAM, a storage unit 31 for storing various programs and data, an operation input unit 32, and a display unit 33.

[0023] The memory unit 31 is composed of a non-volatile memory that allows for on-demand writing and reading, such as a hard disk drive or a solid-state drive. The memory unit 31 stores machining data, which is data used for machining the workpiece W, including setting values ​​for machining conditions and a machining program (so-called NC program) that defines the operating position of the table 14 and the operating position of the rotary grinding wheel 11 using coordinate values. Based on the machining data, the electronic control unit 30 performs numerical control for the grinding process by the grinding machine 10, specifically, it controls the operation of each drive unit 21 to 24.

[0024] The operation input unit 32 is an input device such as a mouse, keyboard, touch panel, or buttons. In the grinding machine 10, the processing conditions for processing the workpiece W are input to the electronic control unit 30 through the operation of the operation input unit 32 by the operator. In this embodiment, the relationship between the input processing conditions and the control patterns of each drive unit 21 to 24 that are suitable for those processing conditions is determined in advance, and this relationship is stored in advance in the storage unit 31 of the electronic control unit 30. In the grinding machine 10, based on the processing conditions input to the electronic control unit 30 through the operation of the operation input unit 32, the control patterns of each drive unit 21 to 24 are set from the above relationship stored in the storage unit 31. This control pattern is stored in the storage unit 31 as processing operation information (processing program). The electronic control unit 30 controls the operation of each drive unit 21 to 24 by operating each drive unit 21 to 24 based on this processing program.

[0025] The display unit 33 has a display device such as a liquid crystal display or an organic EL display. The display unit 33 displays various information related to processing by the grinding machine 10, such as displaying shape data formed by the shape estimation unit 43, which will be described later.

[0026] The grinding machine 10 is equipped with various sensors for detecting its operating state. The detection signals from these sensors are received by the electronic control unit 30. The sensors include a rotation phase sensor 34, a first distance sensor 35, and a second distance sensor 36.

[0027] The rotational phase sensor 34 is attached to the electric motor 241 (Figure 1) and detects the rotational phase of the rotation axis 111 of the rotating grinding wheel 11 (specifically, the output shaft of the electric motor 241). As shown in Figure 4, the first distance sensor 35 and the second distance sensor 36 are attached to the grinding wheel support 12. The first distance sensor 35 and the second distance sensor 36 are, for example, eddy current displacement sensors. The first distance sensor 35 and the second distance sensor 36 are installed to detect the gaps G1 and G2 between the inner surface of the bearing portion 121 of the grinding wheel support 12 and the outer surface of the rotation axis 111 of the rotating grinding wheel 11. Note that in Figure 4, the gaps G1 and G2 are shown exaggerated compared to the actual gaps for ease of understanding.

[0028] The electronic control unit 30 calculates and detects the amount of displacement of the rotating grinding wheel 11 relative to the grinding wheel support part 12 in the first direction (hereinafter referred to as the first displacement amount D1) based on the gap G1 in the first direction (Y direction) detected by the first distance sensor 35. In this embodiment, the first distance sensor 35 corresponds to the first detection unit.

[0029] Furthermore, the electronic control unit 30 calculates and detects the amount of displacement of the rotating grinding wheel 11 relative to the grinding wheel support 12 in the second direction (hereinafter referred to as the second displacement amount D2) based on the gap G2 in the second direction (X direction) detected by the second distance sensor 36. In this embodiment, the second distance sensor 36 corresponds to the second detection unit.

[0030] As described above, the rotating shaft 111 of the rotating grinding wheel 11 is supported in a rotatable state by the grinding wheel support part 12 by an oil hydrostatic bearing. Specifically, the rotating shaft 111 of the rotating grinding wheel 11 is substantially cylindrical and is inserted through a bearing part 121 formed in the grinding wheel support part 12.

[0031] Here, as shown in Figure 5 as an example, it is difficult to make the cross-sectional shape of the rotating shaft 111 a perfect circle. Therefore, the gap G1 in the first direction detected by the first distance sensor 35 and the rotation phase sensor 34 when no processing is taking place, i.e., when no force is being applied to the rotating grinding wheel 11 from the workpiece W, and the gap G1 corresponding to each rotation phase of the rotating grinding wheel 11, are not constant. This variation in gap G1 becomes an error factor in detecting the first displacement amount D1. Similarly, the gap G2 in the second direction detected by the second distance sensor 36 and the rotation phase sensor 34 when no processing is taking place, and the gap G2 corresponding to each rotation phase of the rotating grinding wheel 11, are also not constant. And this variation in gap G2 becomes an error factor in detecting the second displacement amount D2.

[0032] In this embodiment, a value that serves as a reference for detecting the first displacement amount D1 is defined as the first reference position BG1, corresponding to each rotational phase of the rotating grinding wheel 11, or more specifically, the rotating shaft 111 connected to the rotating grinding wheel 11. Specifically, the first reference position BG1 is defined as a value corresponding to the gap G1 when the first displacement amount D1 becomes "0". In addition, a value that serves as a reference for detecting the second displacement amount D2 (specifically, a value corresponding to the gap G2 when the second displacement amount D2 becomes "0") is defined as the second reference position BG2, corresponding to each rotational phase of the rotating grinding wheel 11. The first reference position BG1 and the second reference position BG2 are stored in the storage unit 31 of the electronic control device 30.

[0033] As shown in Figure 2, the electronic control unit 30 includes a first reference position correction unit 41 and a second reference position correction unit 42 as functional units. <First reference position correction section 41> The first reference position correction unit 41 corrects the first reference position BG1 for detecting the first displacement amount D1 based on the gap G1 corresponding to each rotation phase of the rotating grinding wheel 11 detected by the first distance sensor 35 and the rotation phase sensor 34 when not processing. The first reference position BG1 is corrected as follows.

[0034] First, when the rotating grinding wheel 11 is being driven and not being machined, that is, when the rotating shaft 111 is not displaced in the first direction (Y direction) relative to the grinding wheel support 12, the first distance sensor 35 and the rotation phase sensor 34 detect the gap G1 corresponding to each rotation phase of the rotating shaft 111. Then, for each rotation phase, the detected gap G1 is stored as the first reference position BG1. In this way, the first reference position BG1 corresponding to each rotation phase is updated (corrected). This makes it possible to offset the first reference position BG1 corresponding to each rotation phase to match the shape of the rotating shaft 111. Therefore, by subtracting the first reference position BG1 corresponding to a given rotation phase from the gap G1 detected at that rotation phase, the first displacement amount D1 can be detected with high accuracy.

[0035] <Second reference position correction section 42> The second reference position correction unit 42 corrects the second reference position BG2 for detecting the second displacement amount D2 based on the gap G2 corresponding to each rotation phase of the rotating grinding wheel 11 detected by the second distance sensor 36 and the rotation phase sensor 34 when not processing. The second reference position BG2 is corrected as follows.

[0036] First, when the rotating grinding wheel 11 is being driven and not processing, that is, when the rotating shaft 111 is not displaced in the second direction (X direction) relative to the grinding wheel support 12, the second distance sensor 36 and the rotation phase sensor 34 detect the gap G2 corresponding to each rotation phase of the rotating shaft 111. Then, for each rotation phase, the detected gap G2 is stored as the second reference position BG2. In this way, the second reference position BG2 corresponding to each rotation phase is updated (corrected). This allows the second reference position BG2 corresponding to each rotation phase to be offset to match the shape of the rotating shaft 111. For example, in the example shown in Figure 5, the second reference position BG2 corresponding to this rotation phase can be offset by the amount indicated by "ΔBG" in the figure. Therefore, by subtracting the second reference position BG2 corresponding to a given rotation phase from the gap G2 detected at that rotation phase, the second displacement amount D2 can be detected with high accuracy.

[0037] <Shape estimation unit 43> As shown in Figure 2, the electronic control unit 30 includes a shape estimation unit 43 as a functional unit. The shape estimation unit 43 estimates the shape of the machined surface of the workpiece W based on the relative position PM of the grinding wheel support unit 12 and the table 14, the first displacement amount D1, and the second displacement amount D2. More specifically, the shape estimation unit 43 creates data (hereinafter referred to as shape data) that shows the shape of the machined surface of the workpiece W. The shape data is data in which the relationship between the relative position PM and the displacement position of the rotating grinding wheel 11 relative to the grinding wheel support unit 12 (positional displacement amount ΔPR, described later), which is determined by the first displacement amount D1 and the second displacement amount D2 at the same relative position PM, is defined separately for multiple relative positions PM.

[0038] In this embodiment, the shape data consists of "table data," an example of which is shown in Figure 6, and "image data," an example of which is shown in Figure 7. As shown in Figure 6, the table data is data that summarizes the relationship between the relative position PM, the positional displacement amount ΔPR, and the actual machining point (actual machining point PRr) on the workpiece W in a table. As shown in Figure 7, the image data is data created by plotting the actual machining point PRr at each relative position PM on a 3D coordinate system. In this embodiment, the shape data (specifically, the table data and image data) created by the shape estimation unit 43 is stored in the storage unit 31 and output to the display unit 33 for display. According to this embodiment, the shape of the machined surface of the workpiece W can be checked in real time during machining by the table data and image data displayed on the display unit 33. Furthermore, based on the shape data stored in the storage unit 31, it is also possible to check the shape of the machined surface of the workpiece W at any timing after machining.

[0039] In this embodiment, the shape estimation unit 43 creates shape data based on the following considerations. Figure 8 shows an example of the relative positional relationship between the workpiece W fixed to the table 14 and the rotating grinding wheel 11. The solid line in Figure 8 shows the position of the rotating grinding wheel 11 when the relative position PS between the rotating shaft 111 and the grinding wheel support part 12 is shifted (first displacement D1 ≠ 0, second displacement D2 ≠ 0). The dashed line in Figure 8 shows the position of the rotating grinding wheel 11 when it is assumed that the relative position PS between the rotating shaft 111 and the grinding wheel support part 12 is not shifted (first displacement D1 = 0, and second displacement D2 = 0).

[0040] In this embodiment, during the machining of the workpiece W by the grinding machine 10, the relative position PM of the grinding wheel support 12 and the table 14, the first displacement amount D1, and the second displacement amount D2 are detected at the same timing.

[0041] In this embodiment, the relative position PM of the grinding wheel support 12 and the table 14 is determined by the relationship between the X-direction position of the table 14, the Y-direction position of the grinding wheel support 12, and the Z-direction position of the grinding wheel support 12. Therefore, as shown by the dashed line in Figure 8, this relative position PM allows us to determine the machining point (hereinafter referred to as the basic machining point PRb) when the rotation axis 111 is not displaced in the Y-direction and X-direction relative to the grinding wheel support 12 (first displacement amount D1 = 0, and second displacement amount D2 = 0).

[0042] The first displacement D1 is the displacement of the rotating grinding wheel 11 in the Y direction, and is the displacement of the rotating grinding wheel 11 from the first reference position BG1 relative to the grinding wheel support 12. Therefore, as shown by arrow P1 in Figure 8, this first displacement D1 corresponds to the amount of deviation in the Y direction between the basic machining point PRb and the actual machining point (hereinafter referred to as the actual machining point PRr). Thus, the "amount of deviation in the Y direction" of the actual machining point PRr from the basic machining point PRb can be determined by this first displacement D1.

[0043] The second displacement D2 is the displacement of the rotating grinding wheel 11 in the X direction, and is the displacement of the rotating grinding wheel 11 from the second reference position BG2 relative to the grinding wheel support 12. Therefore, as shown by arrow P2 in Figure 8, this second displacement D2 corresponds to the amount of deviation in the X direction between the basic machining point PRb and the actual machining point PRr. Thus, this second displacement D2 allows us to determine the "amount of deviation in the X direction" of the actual machining point PRr from the basic machining point PRb.

[0044] Based on these considerations, in this embodiment, the position coordinates obtained by shifting the relative position PM (specifically, the basic machining point PRb) in the Y direction by a first displacement amount D1 indicated by arrow P1 in Figure 8, and in the X direction by a second displacement amount D2 indicated by arrow P2 in Figure 8, are determined as the actual machining point PRr. During the machining of the workpiece W, the actual machining point PRr is determined separately for each of the multiple relative positions PM. In this embodiment, data (shape data) is created that defines the relationship between the relative position PM and the actual machining point PRr separately for each of the multiple relative positions PM. In this embodiment, the actual machining point PRr is one of the data showing the relationship between the relative position PM and the positional displacement amount ΔPR of the rotating grinding wheel 11 relative to the grinding wheel support 12, which is determined by the first displacement amount D1 and the second displacement amount D2 at the same relative position PM.

[0045] In this embodiment, a creation program for generating shape data based on the relative position PM, first displacement D1, and second displacement D2 is pre-constructed based on this concept, and this program is stored in the storage unit 31. The shape estimation unit 43 creates the shape data by performing calculation processing based on this creation program.

[0046] <Shape data creation process> The following explains in detail the process of creating shape data (shape data creation process). Figure 9 shows the execution procedure for the shape data creation process. The series of processes shown in the flowchart of Figure 9 are executed by the electronic control device 30 at predetermined intervals, provided that the workpiece W is being machined.

[0047] As shown in Figure 9, this process first determines whether either (Condition A) or (Condition B) is met (Step 11). (Condition A) This is the timing of the first execution of this process after the start of machining of workpiece W.

[0048] (Condition B) A specified period of time has elapsed since the last execution. If both (Condition A) and (Condition B) above are not met (Step S11: NO), the following processes (Steps S12 to S15) will not be executed.

[0049] On the other hand, if either (Condition A) or (Condition B) is met (Step S11: YES), the relative position PM of the grinding wheel support 12 with respect to the table 14 is captured (Step S12). In addition, the first displacement D1 is detected (Step S13), and the second displacement D2 is detected (Step S14).

[0050] Subsequently, shape data is created based on the relative position PM, the first displacement amount D1, and the second displacement amount D2 (step S15). Specifically, in this process, the actual machining point PRr corresponding to the relative position PM is determined based on the relative position PM, the first displacement amount D1, and the second displacement amount D2. Then, the relationship between this actual machining point PRr, the relative position PM, and the positional displacement amount ΔPR is added to the table data, and the same actual machining point PRr is added to the image data.

[0051] In this way, during the shape data creation process, the shape data is updated at predetermined intervals during the machining of the workpiece W, based on the relationship between the relative position PM and the positional displacement ΔPR. This creates shape data (specifically, table data and image data) that shows the shape of the entire machined surface of the workpiece W.

[0052] <Operation and Effects of This Embodiment> The operation and effects of this embodiment will be described below. (1) The grinding machine 10 includes a grinding wheel support section 12 that rotatably supports a rotating grinding wheel 11, a table 14 on which the workpiece W is fixed, and a position changing device 20 that changes the relative position PM of the grinding wheel support section 12 and the table 14. The grinding machine 10 processes the workpiece W with the rotating grinding wheel 11 by changing the relative position PM using the position changing device 20. The direction in which the rotating grinding wheel 11 is pressed against the processing surface of the workpiece W is defined as the first direction (Y direction), and the direction in which the relative position PM is changed during processing of the workpiece W is defined as the second direction (X direction). The grinding machine 10 includes a first distance sensor 35, a second distance sensor 36, and a shape estimation unit 43. The first distance sensor 35 detects a first displacement amount D1 of the rotating grinding wheel 11 relative to the grinding wheel support section 12 in the first direction during processing of the workpiece W. The second distance sensor 36 detects the second displacement amount D2 of the rotating grinding wheel 11 relative to the grinding wheel support portion 12 in a second direction during machining of the workpiece W. The shape estimation unit 43 estimates the shape of the machined surface of the workpiece W based on the relative position PM, the first displacement amount D1, and the second displacement amount D2.

[0053] The position coordinates of each part on the machined surface of the workpiece W are determined by the machining point during machining of the workpiece W. The machining point is basically determined by the relative position PM between the grinding wheel support 12 and the table 14 (workpiece W). Furthermore, the relative position PS between the grinding wheel support 12 and the rotating grinding wheel 11 during machining of the workpiece W is not constant and shifts slightly depending on the force that the rotating grinding wheel 11 receives from the workpiece W at the machining point. As the machining point shifts along with this shift in the relative position PS, this effect becomes apparent in the shape of the machined surface of the workpiece W.

[0054] According to the above configuration, the basic position (the basic machining point PRb) for the position coordinates of each part on the machining surface of the workpiece W can be determined based on the relative position PM of the grinding wheel support 12 and the table 14. Furthermore, the amount of displacement of the rotating grinding wheel 11 relative to the grinding wheel support 12 during machining of the workpiece W (specifically, the first displacement amount D1 and the second displacement amount D2) can be used as the positional deviation amount ΔPR from the basic machining point PRb. Therefore, according to the above configuration, by determining the position coordinates shifted by the positional deviation amount ΔPR (see arrow P3 in Figure 8) from the basic machining point PRb, the actual position coordinates (the actual machining point PRr) for each part on the machining surface of the workpiece W can be estimated. Based on this actual machining point PRr, shape data indicating the shape of the machining surface of the workpiece W can be created, and based on this shape data, the shape of the machining surface of the workpiece W can be estimated and understood.

[0055] Thus, with the above configuration, during the machining of the workpiece W by the grinding machine 10, the relative position PM, the first displacement D1, and the second displacement D2 can be obtained by the equipment provided by the grinding machine 10, thereby estimating the shape of the machined surface of the workpiece W. Therefore, special operations such as temporarily stopping the machining of the workpiece W for inspection, temporarily removing the workpiece W (or product) from the grinding machine 10, or preparing separate inspection equipment are unnecessary, making product inspection easy to perform.

[0056] (2) The grinding machine 10 is a surface grinding machine that processes the surface of the workpiece W into a flat surface. The shape estimation unit 43 creates shape data as data indicating the shape of the processed surface of the workpiece W. The shape data is data that defines the relationship between the relative position PM and the displacement position (positional deviation ΔPR) of the rotating grinding wheel 11 relative to the grinding wheel support unit 12, which is determined by the first displacement D1 and the second displacement D2 at the same relative position PM, for each of several relative positions PM.

[0057] According to the above configuration, shape data is obtained that summarizes the positional displacement amount ΔPR, which corresponds to the positional displacement amount of the actual machining point PRr from the basic machining point PRb, for each part of the machining surface of a workpiece W that is machined on a plane, i.e., the machining surface where the basic machining point PRb is located on the same plane. Therefore, based on this shape data, the actual machining point PRr at each part of the machining surface can be determined, and thus the shape of the machining surface of the workpiece W can be estimated and determined. Moreover, the actual machining point PRr and the positional displacement amount ΔPR at each part of the machining surface of the workpiece W can be easily determined from the table data.

[0058] (3) When the direction perpendicular to the first and second directions is defined as the third direction (Z direction), the rotation axis 111 of the grinding wheel 11 extends in the third direction. The first distance sensor 35 is provided on the grinding wheel support 12 and detects the gap G1 between the rotation axis 111 and the grinding wheel support 12 in the first direction (Y direction) as the first displacement amount D1. The grinding machine 10 includes a rotation phase sensor 34 for detecting the rotation phase of the grinding wheel 11 and a first reference position correction unit 41. The first reference position correction unit 41 corrects the first reference position BG1 corresponding to each rotation phase of the grinding wheel 11 based on the gap G1 corresponding to each rotation phase of the grinding wheel 11 detected by the first distance sensor 35 and the rotation phase sensor 34 when not processing. The first reference position BG1 is a reference position for detecting the first displacement amount D1 and is a reference position determined in accordance with each rotation phase.

[0059] According to the above configuration, the first reference position BG1 corresponding to each rotation phase of the rotating grinding wheel 11 can be offset to match the shape of the rotating shaft 111. Therefore, the first distance sensor 35 can detect the first displacement amount D1 with high accuracy.

[0060] (4) The second distance sensor 36 is provided on the grinding wheel support 12 and detects the gap G2 in the second direction (X direction) between the rotating shaft 111 and the grinding wheel support 12 as the second displacement amount D2. The grinding machine 10 includes a rotation phase sensor 34 that detects the rotation phase of the rotating grinding wheel 11 and a second reference position correction unit 42. The second reference position correction unit 42 corrects the second reference position BG2 corresponding to each rotation phase of the rotating grinding wheel 11 based on the gap G2 corresponding to each rotation phase of the rotating grinding wheel 11 detected by the second distance sensor 36 and the rotation phase sensor 34 when not processing. The second reference position BG2 is the reference position for detecting the second displacement amount D2 and is the reference position corresponding to each rotation phase.

[0061] According to the above configuration, the second reference position BG2 corresponding to each rotation phase of the rotating grinding wheel 11 can be offset to match the shape of the rotating shaft 111. Therefore, the second displacement amount D2 can be detected with high accuracy by the second distance sensor 36.

[0062] <Example of changes> The above embodiment can be implemented with the following modifications. The above embodiment and the following modifications can be combined with each other to the extent that they do not contradict each other technically.

[0063] The mounting positions of the first distance sensor 35 and the second distance sensor 36 in the grinding wheel support section 12 can be arbitrarily changed. Furthermore, the first distance sensor 35 and the second distance sensor 36 may be configured using sensors other than eddy current displacement sensors, such as proximity sensors. Essentially, it is sufficient that the first distance sensor 35 can detect the first displacement amount D1 of the rotating grinding wheel 11 relative to the grinding wheel support section 12 in a first direction, and that the second distance sensor 36 can detect the second displacement amount D2 of the rotating grinding wheel 11 relative to the grinding wheel support section 12 in a second direction.

[0064] The first distance sensor 35 and the second distance sensor 36 can be configured using pressure sensors. Here, the rotation axis 111 of the rotating grinding wheel 11 is supported by the grinding wheel support part 12 by an oil hydrostatic bearing. In this oil hydrostatic bearing, oil is filled in the gap between the outer surface of the rotation axis 111 of the rotating grinding wheel 11 and the inner surface of the bearing part 121 of the grinding wheel support part 12. Therefore, when the rotating grinding wheel 11 is displaced relative to the grinding wheel support part 12, the distance of the gap changes, and the hydraulic pressure in the part where the distance has changed changes. When the first distance sensor 35 and the second distance sensor 36 are configured using pressure sensors, the relationship between the distance of the gap and the hydraulic pressure can be obtained from the results of various experiments and simulations and stored in the memory unit 31 in advance. As a result, by detecting the hydraulic pressure with the pressure sensor, the distance of the gap, that is, the distance corresponding to the first displacement amount D1 and the second displacement amount D2, can be determined from the relationship based on the hydraulic pressure.

[0065] The timing for correcting the first reference position BG1 by the first reference position correction unit 41 and the timing for correcting the second reference position BG2 by the second reference position correction unit 42 can be set arbitrarily. For example, the correction by the first reference position correction unit 41 and the correction by the second reference position correction unit 42 can be performed only once when the grinding machine 10 is set up in the factory, or each time the workpiece W is processed.

[0066] • Correction of the first reference position BG1 may be performed by the first reference position correction unit 41, or by inputting the first reference position BG1 corresponding to each rotation phase through the operation of the operation input unit 32.

[0067] • The correction of the second reference position BG2 may be performed not only by the second reference position correction unit 42, but also by inputting the second reference position BG2 corresponding to each rotation phase through the operation of the operation input unit 32.

[0068] - Either the first reference position correction unit 41 or the second reference position correction unit 42 can be omitted, or both can be omitted. The shape data created by the shape estimation unit 43 can be arbitrarily modified as long as it is data that can estimate the shape of the machined surface of the workpiece W. For example, only one of tabular data or image data can be used as shape data. Furthermore, as tabular data, only the relative position PM and positional displacement amount ΔPR may be summarized in a table, only the actual machined points PRr at each part of the machined surface of the workpiece W may be summarized in a table, or the relationship between the basic machined point PRb and the actual machined point PRr may be summarized in a table. In addition, it is also possible to use data that combines image data and tabular data as shape data. In this case, for example, when the cursor is placed over the image displayed on the display unit 33 (the image corresponding to the shape data), the position coordinates and positional displacement amount ΔPR (first displacement amount D1, second displacement amount D2) of that part may be displayed.

[0069] • A machine learning model may be used to create shape data. For example, a machine learning model can be used that takes relative position PM, first displacement D1, and second displacement D2 as input variables and outputs shape data showing the shape of the machined surface of the workpiece W. Alternatively, a machine learning model can be used that takes image data created through the shape data creation process as input variables and outputs final image data showing the shape of the machined surface of the workpiece W. In such cases, a supervised trained model that has been trained with correct answers provided to the training data can be used as the machine learning model.

[0070] The grinding machine 10 according to the above embodiment can also be applied to a grinding machine in which the rotation axis 111 of the rotating grinding wheel 11 extends in the Y direction. The grinding machine 10 according to the above embodiment can also be applied to grinding machines in which the rotation axis 111 of the rotating grinding wheel 11 is supported by a fluid bearing other than an oil hydrostatic bearing, such as a grinding machine in which the rotation axis 111 of the rotating grinding wheel 11 is supported by an air hydrostatic bearing.

[0071] The grinding machine 10 according to the above embodiment is not limited to a surface grinding machine, but can also be applied to a grinding machine that grinds the workpiece surface W into a curved surface. <Note> The above embodiment includes the configuration described in the following appendix.

[0072] [Note 1] A grinding machine having a grinding wheel support section that rotatably supports a rotating grinding wheel, a fixing section for which a workpiece is fixed, and a position changing device for changing the relative position of the grinding wheel support section and the fixing section, wherein the grinding machine processes the workpiece with the rotating grinding wheel by changing the relative position by the position changing device, wherein the direction in which the rotating grinding wheel is pressed against the workpiece surface is defined as the first direction, and the direction in which the relative position is changed during workpiece processing is defined as the second direction, the grinding machine comprises a first detection section that detects a first displacement amount of the rotating grinding wheel relative to the grinding wheel support section in the first direction during workpiece processing, a second detection section that detects a second displacement amount of the rotating grinding wheel relative to the grinding wheel support section in the second direction during workpiece processing, and a shape estimation section that estimates the shape of the processed surface based on the relative position, the first displacement amount, and the second displacement amount.

[0073] [Note 2] The grinding machine is a surface grinding machine that processes the surface of the workpiece into a flat surface, and the shape estimation unit creates data indicating the shape of the processed surface, where the relationship between the relative position and the displacement position of the rotating grinding wheel relative to the grinding wheel support, which is determined by the first and second displacement amounts at the relative position, is defined separately for each of the multiple relative positions.

[0074] [Note 3] When the direction perpendicular to the first and second directions is defined as the third direction, the rotation axis of the grinding wheel extends in the third direction, the first detection unit is provided on the grinding wheel support and is a first distance sensor that detects the gap between the rotation axis and the grinding wheel support in the first direction as the first displacement amount, the grinding machine comprises a phase sensor that detects the rotation phase of the grinding wheel, and a first reference position correction unit that is a first reference position for detecting the first displacement amount and corrects the first reference position corresponding to each rotation phase based on the gap corresponding to each rotation phase of the grinding wheel detected by the first distance sensor and the phase sensor when not processing, the grinding machine according to [Note 1] or [Note 2].

[0075] [Note 4] When the direction perpendicular to the first and second directions is defined as the third direction, the rotation axis of the grinding wheel extends in the third direction, the second detection unit is provided on the grinding wheel support and is a second distance sensor that detects the gap between the rotation axis and the grinding wheel support in the second direction as the second displacement amount, the grinding machine comprises a phase sensor that detects the rotation phase of the grinding wheel, and a second reference position correction unit that is a second reference position for detecting the second displacement amount and corrects the second reference position corresponding to each rotation phase based on the gap corresponding to each rotation phase of the grinding wheel detected by the second distance sensor and the phase sensor when not processing, as described in any one of [Appendix 1] to [Appendix 3]. [Explanation of Symbols]

[0076] W...work D1...First displacement D2...Second displacement 10… Grinding machine 11… Rotary grinding wheel 111... Rotation axis 12…Grinding wheel support section 121...Bearing part 13…Base 14... Table 20... Position change device 21...X-axis drive unit 22...Y-axis drive unit 23...Z-axis drive unit 24…Grinding wheel drive unit 241… Electric motor 30…Electronic control unit 31...Storage section 32... Operation input section 33…Display section 34…Rotational phase sensor 35…First distance sensor 36…Second distance sensor 41...First reference position correction section 42…Second reference position correction section 43...Shape estimation section

Claims

1. A grinding machine comprising a grinding wheel support section that rotatably supports a rotating grinding wheel, a fixing section for which a workpiece is fixed, and a position changing device that changes the relative position of the grinding wheel support section and the fixing section, wherein the grinding machine processes the workpiece with the rotating grinding wheel through the change of the relative position by the position changing device, When the direction in which the rotating grinding wheel is pressed against the machined surface of the workpiece is defined as the first direction, and the direction in which the relative position is changed during the machining of the workpiece is defined as the second direction, The aforementioned grinding machine, A first detection unit detects a first displacement amount of the rotating grinding wheel relative to the grinding wheel support in the first direction during the machining of the workpiece, During the machining of the workpiece, a second detection unit detects a second displacement amount of the rotating grinding wheel relative to the grinding wheel support in the second direction, A shape estimation unit that estimates the shape of the machined surface based on the relative position, the first displacement, and the second displacement, A grinding machine equipped with the following features.

2. The grinding machine is a surface grinding machine that processes the surface of the workpiece to a flat surface, The shape estimation unit creates data representing the shape of the machined surface, where the relationship between the relative position and the displacement position of the rotating grinding wheel relative to the grinding wheel support, determined by the first and second displacement amounts at the said relative position, is defined separately for each of the multiple relative positions. The grinding machine according to claim 1.

3. When the direction perpendicular to the first and second directions is defined as the third direction, The rotation axis of the aforementioned grinding wheel extends in the third direction, The first detection unit is provided on the grinding wheel support unit and is a first distance sensor that detects the gap between the rotation axis and the grinding wheel support unit in a first direction as the first displacement amount. The aforementioned grinding machine, A phase sensor for detecting the rotational phase of the rotating grinding wheel, The system includes a first reference position correction unit that corrects the first reference position corresponding to each rotation phase of the grinding wheel, which is a first reference position for detecting the first displacement amount, based on the gap corresponding to each rotation phase detected by the first distance sensor and the phase sensor when not processing, The grinding machine according to claim 1 or 2.

4. When the direction perpendicular to the first and second directions is defined as the third direction, The rotation axis of the aforementioned grinding wheel extends in the third direction, The second detection unit is provided on the grinding wheel support unit and is a second distance sensor that detects the gap between the rotation axis and the grinding wheel support unit in the second direction as the second displacement amount. The aforementioned grinding machine, A phase sensor for detecting the rotational phase of the rotating grinding wheel, The system includes a second reference position correction unit that corrects the second reference position corresponding to each rotation phase of the grinding wheel, which is a second reference position for detecting the second displacement amount, based on the gap corresponding to each rotation phase detected by the second distance sensor and the phase sensor when not processing, The grinding machine according to claim 1 or 2.

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