Diagnostic method for holding table and processing method for object to be processed

Abstract

The invention provides a method for diagnosing a holding table and a method for processing an object to be processed, which can accurately diagnose the state of the holding table. A diagnostic method for diagnosing the state of a holding table includes: a fluid supply step of supplying a liquid or a two-fluid formed by mixing a liquid and a gas to a holding surface (26) of the holding table (13); a suction step in which, after the fluid supply step, the liquid or the two-fluid supplied to the holding surface is sucked; an imaging step in which, after the attracting step, the holding surface is imaged to acquire an image; and a detection step of performing image processing on the image and detecting the region in which the liquid or the two-fluid remains as abnormal.

Description

Technical Field

[0001] This invention relates to a diagnostic method for a holding workbench used to hold objects and a method for processing objects. Background Technology

[0002] In a machining apparatus that processes a workpiece, the workpiece is attracted and held on the holding surface of a holding table for processing. However, in such a holding table, if foreign matter such as machining chips becomes clogged in the holding surface, the workpiece may not be able to be held stably.

[0003] In the processing apparatus disclosed in Patent Document 1, an image is taken and processed while air (gas) and water are sprayed onto the holding surface of the holding table, and the blockage status of the holding table is detected based on the image of the holding surface.

[0004] Patent Document 1: Japanese Patent Application Publication No. 2018-114563

[0005] As in Patent Document 1, the method of directly photographing the fluid ejected from the inside of the holding stage into the holding surface to determine blockages in the holding surface has the following problem: if the blockage is minor, it cannot be detected. Therefore, it is desirable to detect abnormalities earlier and with higher accuracy when using a holding stage to attract and hold an object. Summary of the Invention

[0006] The object of the present invention is to provide a method for accurately diagnosing the state of a holding table that holds an object, and a method for processing an object in which the state of the holding table has been accurately diagnosed.

[0007] One aspect of the present invention is a diagnostic method for diagnosing the state of a holding table, wherein the diagnostic method comprises the following steps: a fluid supply step, supplying a liquid or a mixture of a liquid and a gas to the holding surface of a holding table having a holding surface for holding an object; an aspiration step, after the fluid supply step, aspirating the liquid or the mixture of the liquid and gas supplied to the holding surface; an image capture step, after the aspiration step, capturing an image of the holding surface; and a detection step, performing image processing on the image to detect areas where the liquid or the mixture of the liquid and gas remains as abnormal.

[0008] Alternatively, in the shooting step, only the outer peripheral area of ​​the holding surface other than the central area can be photographed.

[0009] One embodiment of the present application is a processing method of an object to be processed, including: a fluid supply step of supplying a liquid or a two-fluid in which a liquid and a gas are mixed to a holding surface of a holding table having the holding surface; a suction step of suctioning the liquid or the two-fluid supplied to the holding surface after the fluid supply step; a photographing step of photographing the holding surface after the suction step to obtain an image; a detection step of detecting, by image processing, a region in which the liquid or the two-fluid remains as an abnormality; and a processing step of holding an object to be processed on the holding table in which the abnormality is not present after the detection step, and processing the object to be processed by an arbitrary processing unit.

[0010] In the processing step, the object to be processed is processed, for example.

[0011] According to the diagnosis method of the holding table of the present application, the liquid or the two-fluid is suctioned after the liquid or the two-fluid is supplied to the holding surface of the holding table, and an abnormality is detected from an image obtained by photographing the holding surface after the suction. Thus, the state of the holding table related to suction and holding of an object to be held can be accurately diagnosed. Further, according to the processing method of the object to be processed of the present application, the object to be processed can be processed in a state in which the state of the holding table is accurately diagnosed. BRIEF DESCRIPTION OF DRAWINGS

[0012] Figure 1 is a perspective view of a processing apparatus having a holding table.

[0013] Figure 2 is a view illustrating a fluid supply step.

[0014] Figure 3 is a view illustrating a fluid supply step.

[0015] Figure 4 is a view illustrating a suction step and a photographing step.

[0016] Figure 5 is a view illustrating a result of photographing a holding table in a state in which there is no abnormality.

[0017] Figure 6 is a view illustrating a result of photographing a holding table in a state in which there is an abnormality.

[0018] Figure 7 is a flowchart illustrating an example of processing of a diagnosis method.

[0019] REFERENCE NUMERALS

[0020] 10: Machining device; 11: Rough grinding mechanism; 12: Fine grinding mechanism; 13: Holding table; 14: Workpiece (holding object, processed object); 15: Control unit; 21: Turntable; 23: Frame; 24: Recess; 25: Perforated plate; 26: Holding surface; 27: Annular upper surface; 28: Inner upper surface; 30: Suction source; 31: Air supply source; 32: Liquid supply source; 33: Flow path; 34: On / off valve; 35: On / off valve; 36: On / off valve; 41: Transfer robot; 42: Temporary worktable; 44: First transfer unit; 4 5: Second conveying unit; 46: Rotary worktable; 47: Cleaning nozzle; 50: Rough grinding mechanism (processing unit); 51: Rough grinding tool; 53: Grinding wheel; 57: Liquid supply source; 58: Flow path; 59: Supply port; 60: Fine grinding mechanism (processing unit); 61: Fine grinding tool; 63: Grinding wheel; 67: Liquid supply source; 68: Flow path; 69: Supply port; 70: Liquid supply nozzle; 71: Liquid supply source; 72: Imaging unit; 73: Image processing unit; 74: Detection unit; Q: Fluid layer; Q': Fluid residue area. Detailed Implementation

[0021] The diagnostic method for maintaining the worktable disclosed herein will be described below with reference to the accompanying drawings. Figure 1 The processing apparatus 10 shown is a grinding apparatus, which has grinding mechanisms (rough grinding mechanism 11 and fine grinding mechanism 12) as processing mechanisms to perform grinding processing on the workpiece 14 held by the holding table 13. The workpiece 14 is the object held by the holding table 13. The diagnostic method described later diagnoses the condition of the holding table 13. The X-axis, Y-axis, and Z-axis directions shown in each figure are perpendicular to each other. The X-axis and Y-axis directions are horizontal. The Z-axis direction is vertical, with +Z being upward and -Z being downward.

[0022] The processing apparatus 10 of this embodiment is an apparatus for performing rough grinding using the rough grinding mechanism 11 and fine grinding using the fine grinding mechanism 12, and has three holding tables 13, but the number of grinding mechanisms and holding tables is not limited. For example, the grinding mechanism and the holding table may each be one.

[0023] Furthermore, the holding table used for diagnosis using the diagnostic method of the present invention can also be installed in processing apparatuses or handling apparatuses other than grinding apparatuses. For example, the diagnostic method of the present invention can also be applied to the diagnosis of holding tables installed in grinding apparatuses, cutting apparatuses, laser processing apparatuses, etc. Additionally, the diagnostic method of the present invention can also be applied to the diagnosis of holding tables that hold objects during processing other than machining; cleaning of the objects being held is an example of such processing.

[0024] The control unit 15 of the machining apparatus 10 consists of a processor that performs various processes and a memory that stores programs. Under the control of the control unit 15, the machining apparatus 10 automatically performs a series of operations on the workpiece 14, including loading, rough grinding, fine grinding, cleaning, and unloading.

[0025] A circular plate-shaped turntable 21 is provided on the base 20 of the processing apparatus 10. The turntable 21 is supported so as to be able to rotate about an axis extending in the Z-axis direction, and is rotated by a turntable rotation mechanism 22 equipped with a motor. Three holding worktables 13 are supported on the turntable 21. The three holding worktables 13 are arranged at equal intervals (120° intervals) in the circumferential direction of the turntable 21.

[0026] Reference Figures 2 to 4 The structure of each holding table 13 will be described. Each holding table 13 includes: a frame 23; and a circular perforated plate 25, which is installed in a recess 24 on the upper surface side of the frame 23. The perforated plate 25 is made of a porous material such as ceramic, and has fine pores formed throughout. With the perforated plate 25 installed in the recess 24, the upper surface of the frame 23 and the upper surface of the perforated plate 25 are at the same level, forming a holding surface 26 for placing and holding the workpiece 14. The holding surface 26 is composed of an annular upper surface 27, which is the upper surface of the frame 23, and an inner upper surface 28, which is the upper surface of the perforated plate 25. Figure 5 and Figure 6 When viewed from above, the inner upper surface 28 is located inside the annular upper surface 27. Each holding table 13 can be rotated via the holding table rotation mechanism 29. While details of the holding table rotation mechanism 29 are omitted from the diagram, it is configured as follows: The rotation shaft (not shown) supporting the holding table 13 is supported by annular bearings (not shown) and the like, allowing it to rotate relative to the base portion (not shown) provided on the turntable 21 side. Furthermore, the rotation of the motor (not shown) is transmitted to the aforementioned rotation shaft via a transmission mechanism (not shown) such as a belt, thereby causing the holding table 13 to rotate.

[0027] A flow path 33 is provided, connecting the suction source 30, air supply source 31, and liquid supply source 32 to the perforated plate 25 respectively. One end of the flow path 33 opens at the bottom of the recess 24 of the frame 23. In the flow path 33, a portion that rotates with the holding table 13 and a portion that is disposed outside the holding table 13 and does not rotate are connected via a rotary joint. The flow path 33 branches midway, having a portion connected to the suction source 30 via an on / off valve 34, a portion connected to the air supply source 31 via an on / off valve 35, and a portion connected to the liquid supply source 32 via an on / off valve 36.

[0028] The suction source 30 has a suction pump that draws in air (gas). When the suction source 30 is activated and the on / off valve 34 is opened, a suction force is applied to the perforated plate 25 in the recess 24. The workpiece 14 can be drawn and held on the holding surface 26 by the negative pressure generated by this suction force on the inner upper surface 28 of the holding surface 26.

[0029] Air supply source 31 has a compressor that compresses and delivers air. When air supply source 31 is activated and on / off valve 35 is opened, high-pressure air is supplied to the perforated plate 25 in the recess 24 through flow path 33, and air is ejected from the inner upper surface 28 of the holding surface 26. Liquid supply source 32 has a liquid storage tank and a pump that delivers liquid from the tank. When liquid supply source 32 is activated and on / off valve 36 is opened, pressurized liquid is supplied to the perforated plate 25 in the recess 24 through flow path 33, and liquid is ejected from the inner upper surface 28 of the holding surface 26. When both air supply source 31 and liquid supply source 32 are activated and on / off valves 35 and 36 are opened, a mixture of air and liquid is ejected from the inner upper surface 28 of the holding surface 26. After the workpiece 14 held in the holding surface 26 is processed, it can be easily separated from the holding surface 26 by spraying air, liquid or two fluids from the holding surface 26. In addition, by spraying air, liquid or two fluids from the holding surface 26, foreign matter (dirt) such as processing chips that have entered the pores of the perforated plate 25 can be removed.

[0030] With each 120° rotation of the turntable 21, the three holding tables 13 are sequentially positioned at the loading / unloading position, the first machining position, and the second machining position. At the loading / unloading position, the workpiece 14 before machining is loaded onto the holding table 13 and held on the holding surface 26, and the machined workpiece 14 is removed from the holding table 13. At the first machining position, the workpiece 14 held by the holding table 13 undergoes rough grinding by the rough grinding mechanism 50. At the second machining position, the workpiece 14 held by the holding table 13 undergoes fine grinding by the fine grinding mechanism 60. (Refer to...) Figure 1 The overall structure of the processing apparatus 10 and the series of processes performed using the processing apparatus 10 will be described. The operation of the following parts in the processing apparatus 10 is executed by the control unit 15.

[0031] The workpiece 14 to be processed is stored in the box 40 placed on the base 20. The workpiece 14 is transported from the box 40 to the temporary worktable 42 by the transfer robot 41, and the position of the workpiece 14 is determined by the contact of multiple positioning pins 43 with the outer periphery of the workpiece 14 placed on the temporary worktable 42.

[0032] The first conveying unit 44 has a conveying pad at the front end of a conveying arm capable of rotation around the Z-axis and lifting along the Z-axis, which can adsorb and hold the upper surface of the workpiece 14. The first conveying unit 44 uses the conveying pad to adsorb and hold the upper surface of the workpiece 14 held by the temporary worktable 42, and then moves the conveying arm to place the workpiece 14 onto the holding surface 26 of the holding worktable 13 in the infeed / outfeed position for handover. The suction source 30 is activated and the on / off valve 34 is opened, attracting and holding the workpiece 14 onto the holding surface 26 (the inner upper surface 28 of the perforated plate 25) of the holding worktable 13 by applying negative pressure.

[0033] Rotate the turntable 21 by 120° to move the holding table 13, which holds the workpiece 14 before processing, to the first processing position. Above the first processing position is a rough grinding tool 51 of the rough grinding mechanism 50. The rough grinding tool 51 is arranged in a ring on the lower surface of the grinding wheel 53, which is located at the lower end of the spindle 52 extending along the Z-axis. The spindle 52 is rotated by a motor (not shown). The rough grinding mechanism 50 is supported on a lifting table 54 that can move along the Z-axis, and a ball screw 55 extending along the Z-axis is screwed onto the lifting table 54. When the ball screw 55 is rotated by the motor 56, the lifting table 54 moves along the Z-axis, and the position of the rough grinding mechanism 50 changes along the Z-axis with the lifting table 54.

[0034] During rough grinding, the spindle 52 is rotated, and the table rotation mechanism 29 is maintained (see reference). Figures 2 to 4 The worktable 13 is rotated, driving the motor 56 to lower the rough grinding mechanism 50. This causes the rough grinding wheel 51 and the workpiece 14 to rotate relative to each other, pressing the rough grinding wheel 51 against the upper surface of the workpiece 14 to perform grinding. Liquid (e.g., pure water) is supplied from the liquid supply source 57 to the vicinity of the machining point where the rough grinding wheel 51 contacts the workpiece 14. The supplied liquid is used for cooling the area near the machining point and for cleaning machining chips generated during processing.

[0035] After the workpiece 14 is ground to the desired thickness by rough grinding, the motor 56 drives the rough grinding mechanism 50 to rise, separating the rough grinding tool 51 from the workpiece 14. Next, the turntable 21 is rotated 120°, moving the holding table 13, which holds the rough-ground workpiece 14, to a second processing position. Above the second processing position, the fine grinding tool 61 of the fine grinding mechanism 60 is positioned. The fine grinding tool 61 contains abrasive grains finer than those contained in the rough grinding tool 51. The fine grinding tool 61 is arranged in a ring on the lower surface of the grinding wheel 63, which is located at the lower end of a spindle 62 extending along the Z-axis. The spindle 62 is rotated by a motor (not shown). The fine grinding mechanism 60 is supported by a lifting table 64 movable along the Z-axis, and a ball screw 65 extending along the Z-axis is screwed into the lifting table 64. When the ball screw 65 is rotated by the motor 66, the lifting worktable 64 moves along the Z-axis, and the position of the fine grinding mechanism 60 changes along the Z-axis with the lifting worktable 64.

[0036] During fine grinding, the spindle 62 is rotated, and the worktable rotation mechanism 29 (see reference) is used to maintain the rotation of the worktable. Figures 2 to 4 The worktable 13 is rotated, driving the motor 66 to lower the fine grinding mechanism 60. This causes the fine grinding wheel 61 and the workpiece 14 to rotate relative to each other, pressing the fine grinding wheel 61 against the upper surface of the workpiece 14 to perform grinding. Liquid (e.g., pure water) is supplied from the liquid supply source 67 to the vicinity of the machining point where the fine grinding wheel 61 contacts the workpiece 14. The supplied liquid is used for cooling the area near the machining point and for cleaning machining chips generated during processing.

[0037] After the workpiece 14 is ground to the desired thickness by fine grinding, the motor 66 is driven to raise the fine grinding mechanism 60, causing the fine grinding tool 61 to separate from the workpiece 14. Then, the turntable 21 is rotated 120°, and the holding table 13 holding the finely ground workpiece 14 is moved to the loading / unloading position.

[0038] The second conveying unit 45 has a conveying pad at the front end of a conveying arm capable of rotation around the Z-axis and lifting along the Z-axis, which can attract and hold the upper surface of the workpiece 14. The second conveying unit 45 uses the conveying pad to attract and hold the upper surface of the workpiece 14 (which has undergone rough and fine grinding) positioned on the holding table 13 at the inlet / outlet location. The conveying arm then moves to place the workpiece 14 onto the rotary table 46 for transfer. The workpiece 14 is attracted and held against the holding surface of the rotary table 46. While the rotary table 46 rotates, cleaning liquid is sprayed from the cleaning nozzle 47 toward the workpiece 14 to clean it. After cleaning, air is blown from the cleaning nozzle 47 to dry the workpiece 14. The cleaned workpiece 14 is then removed from the rotary table 46 and stored in a box 48 by the conveying robot 41.

[0039] As described above, a series of processes are performed on the workpiece 14 in the processing apparatus 10. The process for processing one workpiece 14 has been explained above, but in the processing apparatus 10, rough grinding and fine grinding of two workpieces 14 can also be performed simultaneously. Furthermore, three or more workpieces 14 can be sequentially fed to the processing apparatus 10 and continuously subjected to processes including rough grinding and fine grinding.

[0040] When processing the workpiece 14 using the processing apparatus 10, it is required that the entire lower surface of the workpiece 14, which is the object to be held, be in close contact with the holding surface 26 of the holding table 13. When the workpiece 14 partially floats off the holding surface 26, the following adverse conditions may occur: the workpiece 14 cannot be ground to a uniform thickness, and the floating portion of the workpiece 14 may be damaged during grinding. As described above, the holding table 13 actuates the suction source 30, causing the suction force to act on the perforated plate 25 to attract and hold the workpiece 14 on the holding surface 26. Therefore, in order to achieve stable holding of the workpiece 14 by the holding surface 26, it is necessary to ensure that the suction force from the suction source 30 acts uniformly on the holding surface 26 (especially the inner upper surface 28 of the perforated plate 25). However, when foreign matter such as machining chips generated during the machining of the workpiece 14 by the machining apparatus 10 enters the interior (pores) of the porous plate 25 made of porous material and causes blockage, the holding performance of the holding table 13 for the workpiece 14 decreases. For example, when the attraction force on the outer peripheral area of ​​the holding surface 26 is insufficient due to blockage of the porous plate 25, the edge of the workpiece 14 is prone to lift off the holding surface 26, which may result in edge defects or chipping. The diagnostic method of this disclosure described below is used to detect with high precision whether the holding table 13 is blocked.

[0041] [Fluid Supply Procedure]

[0042] In the fluid supply step, fluid, serving as a marker for determining blockage in the holding table 13, is supplied to the holding surface 26 of the holding table 13. The fluid supplied in this step is capable of being photographed and detected in the imaging and detection steps described later; specifically, it is a liquid or a two-fluid mixture of liquid and gas. For example, pure water is used as a liquid. As an example of a method for supplying fluid to the holding surface 26 in the fluid supply step, Figure 2 This illustrates the method of supplying liquid from inside the holding table 13. Figure 3 The method of supplying liquid from the outside of the holding table 13 is shown.

[0043] like Figure 2 As shown, when liquid is supplied from the inside of the holding table 13 to the holding surface 26, the on / off valve 36 is opened, and liquid is delivered from the liquid supply source 32. At this time, the on / off valves 34 and 35 are set to the closed state, so that suction based on the suction source 30 and air supply from the air supply source 31 are not performed. The liquid delivered from the liquid supply source 32 is supplied to the perforated plate 25 through the flow path 33, and leaks out onto the holding surface 26 through the air holes in the perforated plate 25, forming a fluid layer Q covering the holding surface 26.

[0044] After a predetermined time sufficient for the formation of fluid layer Q, the on / off valve 36 is closed, stopping the delivery of liquid from the liquid supply source 32. For example, the supply of liquid to the holding surface 26 during the fluid supply step is set to last approximately 5 seconds.

[0045] Alternatively, the amount of liquid supplied from the liquid supply source 32 can be monitored, and after a sufficient amount of liquid to form the fluid layer Q has been supplied, the on / off valve 36 can be closed to stop the supply of liquid from the liquid supply source 32.

[0046] Alternatively, during the fluid supply step, the holding surface 26 can be photographed by an imaging unit capable of photographing it (or the imaging unit 72 used in the imaging step described later). After confirming the formation of the fluid layer Q using the image, control is applied to stop the delivery of liquid from the liquid supply source 32. The reflectivity and refractive index of light differ when the holding surface 26 is exposed and when the fluid layer Q is formed on the holding surface 26. Therefore, by performing image processing such as binarization on the photographed image, it is possible to determine whether the fluid layer Q has formed.

[0047] Furthermore, even if the porous plate 25 becomes partially blocked, preventing liquid from leaking directly from its interior to a portion of the retaining surface 26 (or, if the time required for liquid to leak to a portion of the retaining surface 26 is very long), a fluid layer Q can be formed across the entire retaining surface 26 by expanding the liquid supplied to other areas of the retaining surface 26. In this case, the retaining table 13 can also be rotated at a low speed by the retaining table rotation mechanism 29, allowing the liquid to easily expand across the retaining surface 26 using centrifugal force.

[0048] In the fluid supply step, simultaneously with supplying liquid from the liquid supply source 32, the on / off valve 35 can be opened to supply air from the air supply source 31, supplying a two-fluid mixture of liquid and air (gas) to the perforated plate 25. When the fluid layer Q formed on the holding surface 26 is composed of two fluids, it can also be used as a marker to determine if the holding stage 13 is blocked. That is, the fluid layer Q formed in the fluid supply step only needs to contain liquid components that can be photographed (visualized) in a subsequent photographing step; the fluid layer Q can be composed of only liquid or it can be composed of two fluids.

[0049] like Figure 3 As shown, when liquid is supplied from the outside of the holding table 13 to the holding surface 26, a first method of supplying liquid from the rough grinding mechanism 50 and the fine grinding mechanism 60, and a second method of supplying liquid from the liquid supply nozzle 70 can be applied. Furthermore, in Figure 3 The structure of the first method and the structure of the second method are shown in the text, but it is not necessary to have both of these structures, as long as at least one of them is present.

[0050] As described above, during the machining of workpiece 14, liquid is supplied from the rough grinding unit 50 and the finish grinding unit 60 for cooling the machining point and its surroundings and for cleaning machining chips. The first method of external liquid supply applies this liquid supply from the rough grinding unit 50 and the finish grinding unit 60 to the fluid supply step of the diagnostic method. The structures related to the liquid supply are common in both the rough grinding unit 50 and the finish grinding unit 60, see reference... Figure 3 A unified explanation will be provided.

[0051] like Figure 3As shown, flow paths 58 and 68 are formed inside the spindles 52 and 62 and the grinding wheels 53 and 63. Liquid supplied from liquid supply sources 57 and 67 enters the flow paths 58 and 68 through inlets on the upper end side of the spindles 52 and 62. The outlets of the flow paths 58 and 68 are openings, namely supply ports 59 and 69, formed on the lower surface side of the grinding wheels 53 and 63. Multiple supply ports 59 and 69 are formed at predetermined intervals in the circumferential direction of the grinding wheels 53 and 63. Each supply port 59 and 69 is located radially inside the grinding wheels 53 and 63 compared to the annularly arranged rough grinding tool 51 and fine grinding tool 61. Liquid flowing out from the supply ports 59 and 69 through the flow paths 58 and 68 falls onto the holding surface 26 and expands, thereby forming a fluid layer Q covering the holding surface 26. When forming the fluid layer Q, in order to make it easy for the liquid flowing out from the supply ports 59 and 69 to spread throughout the entire holding surface 26, the holding table 13 based on the holding table rotation mechanism 29 and the grinding wheels 53 and 63 can also be rotated.

[0052] Alternatively, the ball screws 55 and 65 can be rotated by motors 56 and 66, and after the rough grinding mechanism 50 and the fine grinding mechanism 60 are positioned at a suitable height in the Z-axis direction for forming the fluid layer Q, liquid can be supplied from the supply ports 59 and 69. At least the rough grinding tool 51 and the fine grinding tool 61 are positioned upwards and separated from the holding surface 26, thereby enabling the formation of the fluid layer Q without being obstructed by the rough grinding tool 51 and the fine grinding tool 61.

[0053] A second method for supplying liquid from the liquid supply nozzle 70 will be described. For example... Figure 3 As shown, the liquid supply nozzle 70 is connected to the liquid supply source 71. The liquid supply source 71 has a tank for storing liquid and a pump for discharging liquid from the tank. The liquid supplied from the liquid supply source 71 is ejected from the front end of the liquid supply nozzle 70. In the fluid supply step, the liquid ejected from the liquid supply nozzle 70 forms a fluid layer Q covering the retaining surface 26.

[0054] The liquid supply nozzle 70 can be positioned at any of the following locations: the loading / unloading position, the first machining position, and the second machining position of the holding table 13. When the liquid supply nozzle 70 is positioned corresponding to the first or second machining position of the holding table 13, it can also be used as a component to supply liquid to the vicinity of the machining point where the rough grinding wheel 51, the fine grinding wheel 61, and the workpiece 14 come into contact during machining. Located on the outer periphery of the rough grinding wheel 51 and the fine grinding wheel 61, the liquid supply nozzle 70 cools the machining point and its surroundings and cleans machining chips during machining of the workpiece 14.

[0055] When the liquid supply nozzle 70 is positioned to correspond to the loading / unloading position of the holding table 13, and... Figure 3 The difference lies in the configuration where the rough grinding mechanism 50 and the fine grinding mechanism 60 are not positioned above the holding table 13. Furthermore, since the workpiece 14 is not processed during the loading and unloading positions of the holding table 13, the liquid supply nozzle 70 in this case can have a structure that drips liquid downwards or obliquely downwards toward the holding surface 26 (a dedicated structure for forming the fluid layer Q), rather than... Figure 3 The diagram shows a structure that sprays liquid horizontally toward the processing point.

[0056] In either the first method of supplying liquid from the rough grinding mechanism 50 and the fine grinding mechanism 60, or the second method of supplying liquid from the liquid supply nozzle 70, liquid delivery from the liquid supply sources 57, 67, and 71 is stopped after a predetermined time sufficient to form the fluid layer Q. Alternatively, the amount of liquid delivered from the liquid supply sources 57, 67, and 71 may be monitored, and liquid delivery from the liquid supply sources 57, 67, and 71 may be stopped after an amount of liquid sufficient to form the fluid layer Q has been supplied. Alternatively, the holding surface 26 may be photographed by an imaging unit capable of photographing it (or the imaging unit 72 used in the imaging step described later), and after the formation of the fluid layer Q can be confirmed by the image, control is performed to stop liquid delivery from the liquid supply sources 57, 67, and 71.

[0057] In the event of significant blockage in the perforated plate 25, even if it is desired to supply liquid or a two-fluid system from the interior of the holding stage 13 to the perforated plate 25 via the flow path 33, it may be impossible to properly form a fluid layer Q on the holding surface 26. Specifically, this could result in a state where the fluid layer Q is sparsely formed on the holding surface 26, or a state where almost no fluid layer Q is formed on the holding surface 26. In such cases, by utilizing... Figure 3 The method shown allows for the supply of liquid from outside the holding stage 13, and also enables the reliable formation of a fluid layer Q on the holding surface 26. Alternatively, when forming the fluid layer Q on the holding surface 26, a second fluid, rather than a liquid, can be supplied from outside the holding stage 13.

[0058] As described above, in the fluid supply step, liquid or two fluids are supplied from inside or outside the holding stage 13, forming a fluid layer Q on the holding surface 26. The fluid layer Q can be determined based on an image obtained by taking a picture of the holding surface 26 to determine whether the suction of the perforated plate 25 in the subsequent suction step is successful. Even a fluid layer Q composed of a transparent liquid can be used for this determination.

[0059] [Attraction Steps]

[0060] Following the fluid supply step, a suction step is performed to draw away the liquid supplied to the holding surface 26 of the holding table 13. For example... Figure 4 As shown, in the suction step, the suction source 30 is activated and the on / off valve 34 is opened, drawing air from the perforated plate 25 through the flow path 33. The on / off valves 35 and 36 are then set to the closed state, preventing the supply of air from the air supply source 31 and liquid from the liquid supply source 32. After a sufficient time has elapsed to draw the fluid layer Q, the on / off valve 34 is closed, stopping the suction operation of the suction source 30. For example, the suction in this step is set to last approximately 5 seconds.

[0061] When the porous plate 25 is completely unobstructed and the suction force can be uniformly applied to the holding surface 26, the liquid or two fluids forming the fluid layer Q are drawn from the entire holding surface 26 by performing the suction step, leaving no fluid layer Q on the holding surface 26. More specifically, this results in a state where no fluid layer Q remains on the inner upper surface 28 of the holding surface 26. When the porous plate 25 is obstructed, during the suction step, the liquid or two fluids are not drawn and remain on the holding surface 26 in the area where the obstruction exists. The portion of the fluid layer Q remaining on the holding surface 26 during the suction step is defined as the fluid residue area Q' (see reference). Figure 4 and Figure 6 ).

[0062] [Filming Steps]

[0063] After the suction step, an image-taking step is performed to capture an image of the holding surface 26 of the holding table 13. For example... Figure 1 and Figure 4 As shown, the processing device 10 has a shooting unit 72 capable of shooting the holding surface 26. Figure 1 The imaging unit 72 shown is configured to image the holding surface 26 of the holding table 13 positioned at the loading / unloading position, and is mounted on the front end of a movable arm capable of rotating around an axis in the Z-axis direction. When not imaging the holding surface 26, moving the movable arm to disengage the imaging unit 72 from above the holding surface 26 allows the imaging unit 72 to not obstruct the loading and unloading of the workpiece 14 relative to the holding table 13. Alternatively, the imaging unit 72 can be supported and movable in the Z-axis direction, allowing it to disengage upwards (in the +Z direction) when not imaging. Furthermore, the configuration of the imaging unit 72 is not limited to... Figure 1 The configuration shown can also be used to photograph the holding surface 26 of the holding table 13 positioned at the first processing position and the second processing position.

[0064] Furthermore, the positions of the holding table 13 for the fluid supply step and the holding table 13 for the imaging step can be the same or different. For example, the imaging unit 72 can be configured to image the holding surface 26 of the holding table 13 positioned at the loading / unloading position (i.e., Figure 1 In the case of the structure shown, while keeping the worktable 13 in the loading / unloading position, the liquid supply source 32 and the liquid supply nozzle 70 ( Figure 3 Liquid is supplied to the holding surface 26 to form a fluid layer Q (fluid supply step), so that the holding table 13 is directly in the loading / unloading position. After the suction step, the imaging unit 72 takes a picture of the holding surface 26 (imaging step). In this case, the holding table 13 remains in the loading / unloading position during the period from the fluid supply step to the imaging step.

[0065] As a method of moving the holding table 13 during the period from the fluid supply step to the shooting step, for example, liquid can be supplied from the rough grinding mechanism 50 at the first machining position of the holding table 13 or from the fine grinding mechanism 60 at the second machining position of the holding table 13 to form a fluid layer Q on the holding surface 26 (performing the fluid supply step), performing the suction step, then rotating the turntable 21 to move the holding table 13 to the loading and unloading position, and then the shooting unit 72 takes pictures of the holding surface 26 (performing the shooting step).

[0066] Furthermore, it is preferable to complete the suction step and the imaging step within a predetermined time from the implementation of the fluid supply step, so as not to cause the disappearance of the fluid layer Q and the fluid residue area Q' due to natural drying. In particular, when the turntable 21 is rotated and the holding table 13 is moved during the period from the fluid supply step to the imaging step, a time lag occurs before the imaging step is performed, so care must be taken to prevent the disappearance of the fluid layer Q and the fluid residue area Q' due to natural drying.

[0067] During the shooting process, the image is taken in such a way that the upper surface, specifically the inner upper surface 28, of the holding surface 26, particularly the perforated plate 25, is included within the shooting range. When the shooting unit 72's field of view is only a portion of the holding surface 26, it is preferable to move the shooting unit 72 and the holding table 13 relative to each other to shoot the entire circumference of the holding surface 26. This is because blockages in the perforated plate 25 are not necessarily uniformly distributed across the entire circumference of the holding surface 26; shooting only a portion of the circumference may miss any abnormalities in the holding table 13. As a method for moving the shooting unit 72 and the holding table 13 relative to each other, it is preferable to rotate the holding table 13 one revolution by operating the holding table rotation mechanism 29 while holding the shooting unit 72 in a constant position relative to the holding surface 26. This allows for shooting the entire circumference of the holding surface 26 in a short time. Alternatively, the shooting unit 72 can be supported so that it can move horizontally, and the entire circumference of the holding surface 26 can be shot by moving the shooting unit 72 circumferentially. When the shooting unit 72 has a wide-angle optical system, the entire holding surface 26 can be photographed in one go without relative movement between the shooting unit 72 and the holding stage 13 during the shooting process.

[0068] Furthermore, it is not necessary to photograph the entire radial direction of the retaining surface 26; it is also possible to photograph only the specific radial areas of the retaining table 13 that are prone to clogging. When grinding the workpiece 14 using the machining apparatus 10, there is a tendency that foreign objects are less likely to enter the perforated plate 25 in the central region of the retaining surface 26 covered by the workpiece 14, but are more likely to enter and clog the perforated plate 25 in the outer peripheral region of the retaining surface 26 located at the outer edge of the workpiece 14 and beyond. For example, Figure 6 As shown, the portion of the inner upper surface 28 near the outer periphery of the annular upper surface 27 is prone to clogging of the perforated plate 25, i.e., the area where fluid residue region Q' is likely to remain after the suction step. Therefore, when photographing a portion of the radial direction of the holding surface 26 during the imaging step, it is preferable to photograph only the outer periphery of the holding surface 26 excluding the central region, thereby efficiently detecting clogging of the perforated plate 25. In this case, with the imaging unit 72 positioned above the outer periphery of the holding surface 26, the holding stage 13 is rotated relative to the imaging unit 72, thereby enabling the acquisition of an image of the entire periphery of the holding surface 26 in a short time.

[0069] [Detection Steps]

[0070] Next, a detection step is performed to process the image captured in the shooting step and detect areas with residual liquid as abnormalities. The control unit 15 has an image processing unit 73 and a detection unit 74 as functional blocks (see reference).Figure 1 Image processing is performed by the image processing unit 73, and based on the processed image, the detection unit 74 detects any abnormalities in the holding surface 26 based on the residue of liquid or two fluids after the aspiration step.

[0071] Image processing performed by the image processing unit 73 emphasizes the contrast between the holding surface 26 (especially the inner upper surface 28) and the fluid residue area Q', for example, through binarization. When the imaging unit 72 performs imaging in the visible light region, the fluid residue area Q' has a lower brightness than the holding surface 26 and is easily captured as dark. Therefore, when performing image binarization, the inner upper surface 28 of the holding surface 26 is displayed in white, and the fluid residue area Q' is displayed in black.

[0072] The detection unit 74 performs processing based on the image processed by the image processing unit 73 to detect the area where fluid residue region Q' is captured, that is, the area where liquid or two fluids remain, as abnormal. Figure 5 The image shown is obtained after the aspiration step, where there is no fluid residue area Q' on the holding surface 26. In this case, the detection unit 74 determines that there is no abnormality. Figure 6 This illustrates a case where a fluid residue region Q' exists on the holding surface 26 (a case where residual liquid or two fluids are present) in an image obtained after the aspiration step. Figure 6 In the case of a fluid residue area Q', the detection unit 74 determines that there is an abnormality.

[0073] When only the outer periphery of the retaining surface 26 is considered as the detection object in the detection step, the range of the outer periphery (the radial region of the retaining surface 26) for determining the presence or absence of the fluid residue region Q' can be arbitrarily set. As an example, if a fluid residue region Q' exists with a width of 1 mm to 1.5 mm or more in the radial direction from the outer edge of the inner upper surface 28 (the boundary between the annular upper surface 27 and the inner upper surface 28) toward the center of the inner upper surface 28, it is determined to be abnormal.

[0074] In addition, such as Figure 6 As shown, during the inspection step, one or more fluid residue areas Q' may sometimes exist locally (discontinuously) in the circumferential direction of the holding surface 26. Even such a circumferential portion can cause the edge of the workpiece 14 to lift up when blockage occurs in the perforated plate 25, and therefore is preferably determined to be abnormal in the inspection step.

[0075] When the entire area, including not only the outer periphery of the retaining surface 26 but also the central area, is considered as the object of detection in the detection step, it can be set as follows: a predetermined threshold is set for the area of ​​the fluid residue area Q' on the retaining surface 26. Even if a fluid residue area Q' exists, if the area is smaller than the threshold, it is not considered abnormal (it is determined that there is no obstacle to practical suction performance). For example, Figure 6 In this case, if there is an extended fluid residue region Q' in the circumferential direction of surface 26, it is considered an anomaly. However, in the case of extremely small point-like fluid residue regions, as long as their size does not exceed the threshold, they may not be considered an anomaly.

[0076] In addition, when there are multiple fluid residual areas Q', the ratio of the total area of ​​the fluid residual areas Q' in the holding surface 26 to the area of ​​the inner upper surface 28 can also be detected. If the ratio of the total area of ​​the fluid residual areas Q' is above a threshold, it is determined to be abnormal. If the ratio of the total area of ​​the fluid residual areas Q' is less than the threshold, it is determined to be normal.

[0077] Alternatively, the weighting of the detection judgment related to the fluid residue area Q' can be different in the outer peripheral region and the central region of the holding surface 26. For example, when the outer peripheral region of the holding surface 26 is blocked, damage to the edge of the workpiece 14 is more likely to occur. Therefore, in order to reliably prevent damage to the edge of the workpiece 14, even if there is a small fluid residue area Q' in the outer peripheral region of the holding surface 26, it is judged as an anomaly. In contrast, when the central region of the holding surface 26 is blocked, it is less likely to affect the edge damage of the workpiece 14. Therefore, even if there is a fluid residue area Q' in the central region of the holding surface 26 that is slightly larger than that in the outer peripheral region, it can be disregarded as an anomaly.

[0078] If the detection unit 74 detects an abnormality, the control unit 15 notifies the worktable 13 to handle the abnormality via a notification unit (display monitor, indicator light, speaker, etc.) provided by the processing device 10 or a communication device (server, personal computer, tablet computer, smartphone, etc.) that can communicate with the processing device 10.

[0079] As described above, at the locations where blockage occurs in the perforated plate 25, liquid or fluid is not drawn from the holding surface 26 during the suction step and remains there. Therefore, most of the abnormalities detected by the detection unit 74 during the detection step are due to blockage in the perforated plate 25. The holding table 13 has an internal cleaning function that supplies fluid to the perforated plate 25 by supplying air from the air supply source 31 and liquid from the liquid supply source 32, and periodically performs an internal cleaning operation that pushes foreign objects inside the perforated plate 25 onto the holding surface 26 by the pressure of the supplied fluid. In addition, regarding blockage on the surface of the holding surface 26, it is sometimes eliminated by self-grinding to adjust the shape of the holding surface by grinding the inner upper surface 28 of the perforated plate 25 with a grinding wheel. However, even with such routine maintenance, if liquid or fluid residue is detected on the holding surface 26 during the detection step, it is assumed that the foreign object has entered deep inside the perforated plate 25 and cannot be removed. In this state, it is necessary to remove and clean the holding table 13 or replace the perforated plate 25. Therefore, as a notification from the control unit 15 regarding any abnormality in the holding table 13, it is also possible to recommend replacing the holding table 13.

[0080] However, sometimes suction abnormalities occur in the holding table 13 due to reasons other than blockage of the perforated plate 25. For example, poor suction may sometimes result from malfunction of the suction source 30 or the on / off valve 34, or leakage in the flow path 33. Abnormalities in the holding table 13 caused by such reasons can also be detected during the inspection process.

[0081] Reference Figure 7 The flowchart illustrates an example of a diagnostic method that includes the steps described above. Additionally, Figure 7 The fluid in the flowchart refers to a liquid or a two-fluid system. In this processing example, the processing apparatus 10 has a configuration that supplies fluid from the interior of the holding table 13 to the holding surface 26 (see reference). Figure 2 And the structure for supplying fluid from the outside of the holding table 13 to the holding surface 26 (see reference). Figure 3 These fluid supply structures can be appropriately selected.

[0082] The control unit 15 receives a transfer signal to the diagnostic mode for performing diagnostics on the workbench 13, and begins... Figure 7 The transition to diagnostic mode can be performed at any time by the operator, or automatically when the processing unit 10 is started or after a predetermined usage time has elapsed.

[0083] In step 100, liquid or a two-fluid is supplied from the inside of the holding stage 13 to the holding surface 26. If there are no problems such as significant clogging of the perforated plate 25, a fluid layer Q is formed on the holding surface 26 by supplying liquid or a two-fluid from the inside.

[0084] In step 101, it is determined whether a fluid layer Q is properly formed on the holding surface 26. For example, the holding surface 26 can be photographed using the imaging unit 72, and the formation of the fluid layer Q can be determined based on the photographed image. If the imaging unit 72 is not a wide-angle camera, the holding stage 13 and the imaging unit 72 can be moved relative to each other by rotating the holding stage 13 based on the holding stage rotation mechanism 29, thereby enabling the imaging of a larger area of ​​the holding surface 26 to determine the presence or absence of the fluid layer Q.

[0085] If the result of the determination in step 101 is that a fluid layer Q is properly formed on the holding surface 26 ("Yes" in step 101), proceed to step 103. If the result of the determination in step 101 is that a fluid layer Q is not properly formed on the holding surface 26 ("No" in step 101), proceed to step 102, and supply liquid or two fluids from outside the holding table 13 to the holding surface 26. Then, proceed to step 103. Steps 100 to 102 correspond to the fluid supply steps described above.

[0086] In addition, Figure 7 In the flowchart, assuming that the fluid layer Q is reliably formed by the fluid supply from outside the holding table 13, the process proceeds to step 103 after step 102. However, considering that some errors may occur when forming the fluid layer Q using the fluid supply from outside the holding table 13, it is also possible to return to step 101 after step 102 to re-check the formation of the fluid layer Q. Furthermore, it can be controlled as follows: if the formation of the fluid layer Q cannot be detected even after re-checking, it is determined that the diagnosis of the holding table 13 cannot be performed, and the process is initiated from... Figure 7 The process of exiting is handled.

[0087] Step 103 is equivalent to the suction step described above. In step 103, the liquid or two fluids at the holding surface 26 are attracted, and the process proceeds to step 104.

[0088] Step 104 is equivalent to the shooting step described above. In step 104, an image is captured by shooting the holding surface 26, and then the process proceeds to step 105.

[0089] In step 105, the image processing unit 73 processes the captured image, and based on the processed image, the detection unit 74 detects the fluid residue area Q' on the holding surface 26. Then, based on the detection result, in step 106, it is determined whether there is any liquid or fluid residue on the holding surface 26. Steps 105 and 106 are equivalent to the detection steps described above.

[0090] If the test result shows that there is no liquid or two fluids on the holding surface 26 (No in step 106), then the diagnostic result is that the suction holding performance of the holding table 13 is normal. Figure 7 The flowchart exits. Alternatively, after entering "No" in step 106, a step can also be included to notify of a diagnostic result such as "no abnormality".

[0091] If the detection result shows the presence of a fluid residue area Q' (liquid or two fluids) on the holding surface 26 ("Yes" in step 106), a diagnosis of abnormal suction and holding performance of the holding table 13 is made, and the process proceeds to step 107. Alternatively, as described above, a predetermined threshold can be set for the area of ​​the fluid residue area Q' on the holding surface 26; if the area is smaller than the threshold, it is not considered abnormal. Furthermore, as described above, the criteria for detecting the presence or absence of the fluid residue area Q' can vary depending on its location on the holding surface 26 (e.g., the outer and inner peripheral regions of the holding surface 26). In step 107, any abnormality handling, such as notification from the notification unit, is performed. After executing step 107, from... Figure 7 Exit using the flowchart.

[0092] As explained above, according to the diagnostic method for the holding table of this embodiment, after supplying liquid or a fluid to the holding surface 26 of the holding table 13, the liquid or fluid is aspirated, and an image obtained by photographing the holding surface after aspiration is taken to detect whether there is any abnormality in the holding table. Since the determination of whether there is any abnormality is made by photographing the holding surface 26 after aspiration rather than during the stage of supplying liquid or fluid to the holding surface 26, the aspiration and holding performance of the holding table 13 can be accurately detected.

[0093] Unlike this embodiment, when directly photographing the liquid or fluid supplied from the inside of the holding stage 13 to the holding surface 26, the information may not accurately reflect the local suction state (the area capable of suction) on the holding surface 26 due to the spread of the liquid or fluid on the holding surface 26. That is, there is concern that if the perforated plate 25 does not develop a significant blockage, abnormalities cannot be detected, and the accuracy of detecting only local or minor blockages in the perforated plate 25 cannot be obtained. In contrast, in the diagnostic method of the holding stage in this embodiment, after the liquid or fluid is distributed throughout the area of ​​the holding surface 26 that is to be detected, suction is performed, and then the area of ​​the holding surface 26 is photographed to detect abnormalities. Therefore, information accurately reflecting whether suction on the holding surface 26 is successful can be obtained. In particular, compared to the state immediately after the liquid or fluid is supplied from the inside of the holding table 13 to the holding surface 26, the state after the liquid or fluid is drawn away is reduced or expanded, clearly showing traces of the drawing away. Therefore, the diagnostic method of this embodiment has the following advantages: even local blockages or minor blockages in the perforated plate 25 can be easily and accurately detected, and high-precision diagnostic results can be obtained.

[0094] Furthermore, if the blockage of the holding table 13 is significant, even if liquid or a fluid is supplied from inside the holding table 13 toward the holding surface 26 to detect the blockage, the supply itself will be hindered, potentially making accurate diagnosis impossible. In contrast, in the diagnostic method for the holding table of this embodiment, regardless of the method of supplying liquid or a fluid to the holding surface 26, the judgment is made based on the suction result after supplying the liquid or a fluid. Therefore, by switching to supplying liquid or a fluid from outside the holding table 13, this problem can be avoided, and abnormalities of the holding table can be reliably detected.

[0095] Furthermore, in the above embodiment, the fluid layer Q is formed uniformly across the entire holding surface 26. However, if only the outer peripheral region of the holding surface 26 (excluding the central region) is photographed in the imaging step, and anomaly detection is performed only on the outer peripheral region in the detection step, the fluid layer may be formed only in the outer peripheral region of the holding surface 26 (the region included in the imaging range in the imaging step). For example, with... Figure 3 Unlike the liquid supply nozzle 70 shown, this liquid supply nozzle is configured to drip liquid downwards or diagonally downwards toward the holding surface 26. While positioning the liquid supply nozzle above the outer peripheral region of the holding surface 26 and dripping liquid, the holding table 13 is rotated via the holding table rotation mechanism 29. This allows a fluid layer to be formed only in the outer peripheral region of the holding surface 26. When a fluid layer is formed only in the outer peripheral region of the holding surface 26, the amount of liquid or two fluids supplied can be reduced and saved.

[0096] The holding table 13 of the above embodiment has a structure in which a perforated plate 25 is disposed within the recess 24 of the frame 23. However, as a variation of the holding table, it may also have a structure in which multiple perforated plates are disposed within the recess of the frame and are divided in a manner in which no fluid flows between the perforated plates. For example, there is a known holding table with a structure in which a generally circular perforated plate is disposed at the center of the recess of the frame and at least one annular perforated plate is disposed concentrically on its outer side. The present invention can also be applied to the diagnosis of holding tables with such a structure. In this case, the area of ​​attractive force can be selected on a perforated plate basis, and the above-described diagnostic method can be applied to each perforated plate.

[0097] The holding table 13 of the above embodiment has a porous plate 25 made of porous material so that the attraction force acts on the entire inner upper surface 28. However, it can also be used in the diagnosis of holding tables with structures that have attraction grooves and attraction holes locally formed on the holding surface instead of the porous plate 25.

[0098] The above-described embodiment applies to the holding table 13 of a grinding apparatus 10. Typically, during grinding, the object being held is held in a state where it does not protrude outwards from the holding surface of the holding table. Therefore, the outer peripheral region of the holding surface, which is further outwards from the outer edge of the object, is prone to clogging, such as by machining chips. Consequently, there is a high demand for accurately diagnosing clogging and other abnormalities in the holding table used to hold the object during grinding, making the diagnostic method of the holding table of the present invention highly useful. However, the application of the present invention is not limited to grinding apparatuses; it can also be applied to diagnosing holding tables used to hold objects during various other processing methods (e.g., grinding, cutting, laser processing, etc.).

[0099] Furthermore, the diagnostic method of the present invention can also be applied to holding worktables that hold objects during processes other than machining. For example, Figure 1 The rotary table 46 shown attracts and holds the workpiece 14 during cleaning. When the ground workpiece 14 is transferred to the rotary table 46, dirt such as liquid containing machining chips adheres to the lower surface of the workpiece 14. When this dirt is attracted to the rotary table 46, it can cause blockages. Therefore, accurate diagnosis of blockages and other abnormalities is necessary for the rotary table 46, making it an application of this invention. In the case of the rotary table 46, a fluid supply step can be performed using fluid supplied from the cleaning nozzle 47. Furthermore, in... Figure 1The temporary worktable 42 shown is configured to hold the workpiece 14 on the holding surface, and the diagnostic method of the present invention can also be applied to the temporary worktable 42.

[0100] Furthermore, the present invention is not limited to fixed processing devices or handling devices, but can also be applied to the diagnosis of holding worktables in conveying devices that simultaneously attract and hold objects.

[0101] In the processing method of the workpiece of the present invention, after diagnosing the holding worktable using the above-described diagnostic method, the following processing steps are performed: the workpiece is held on the holding worktable, and the workpiece on the holding worktable is processed by any processing unit. The holding worktable used to hold the workpiece in the processing step is either a holding worktable that was not determined to be abnormal in the detection step of the above-described diagnostic method, or a holding worktable that was determined to be abnormal in the detection step of the above-described diagnostic method and has been replaced or maintained to eliminate the abnormality. That is, a holding worktable without abnormalities is used in the processing step.

[0102] The processing steps of this invention involve various types of processing on the workpiece. These include processing that alters the properties and shape of the workpiece, such as grinding, lapping, cutting, and laser processing, as well as processing that does not alter the properties or shape of the workpiece, such as inspection, photographing, and transporting. The processing steps of this invention also encompass the scope of processing performed on the workpiece. Processing the workpiece can also be used as a method for manufacturing an article as a result of the processing. Cleaning can involve removing protective components from the workpiece, causing a significant change in its shape, or it can remove dust from the workpiece without significantly changing its shape; however, both cases are included in the scope of processing performed in the processing steps of this invention.

[0103] In the case of the processing apparatus 10 described above, the processing steps are as follows: the workpiece 14, which is the work to be processed, is held on a holding table 13, which has been diagnosed to have no abnormalities in its suction and holding performance. The workpiece 14 is then ground by a rough grinding mechanism 50 and a fine grinding mechanism 60, which are processing units. That is, when the above-described diagnostic method is applied to the holding table 13, the workpiece 14 is ground in the processing steps performed in the processing apparatus 10 to produce a thinner product through grinding. In addition, this product can also be an intermediate product before it becomes a product that is finally distributed in the market. For example, it can also be applied to a situation where the workpiece 14 is a semiconductor wafer with multiple chips. Multiple chips (final product) are produced by dividing the workpiece 14 (intermediate product) after grinding by the processing apparatus 10 along a predetermined dividing line using a processing apparatus different from the processing apparatus 10.

[0104] The processing steps in the processing apparatus 10 may also include the following: holding the workpiece 14, which has been diagnosed as having normal suction and retention performance, on a rotary table 46, and cleaning the workpiece 14 using a cleaning nozzle 47 constituting the processing unit. Alternatively, the processing steps may include the following: holding the workpiece 14, which has been diagnosed as having normal suction and retention performance, on a temporary worktable 42, and positioning the workpiece 14 using a positioning pin 43 constituting the processing unit.

[0105] Furthermore, the embodiments of the present invention are not limited to the above-described embodiments and modifications, and various changes, substitutions, and modifications can be made without departing from the spirit and essence of the technical concept of the present invention. Additionally, the method can be used to implement the technical concept of the present invention in other ways, as long as it can be achieved through technological advancements or other derived technologies. Therefore, the claims cover all embodiments that can be included within the scope of the technical concept of the present invention.

[0106] Industrial availability

[0107] According to the present invention, the condition of the holding table can be accurately diagnosed, which helps to achieve proper holding of objects in various devices.

Claims

1. A diagnosis method of a holding stage, which diagnoses a state of a holding stage, wherein the diagnosis method of the holding stage has the steps of: a fluid supply step of supplying a liquid or a two-fluid in which a liquid and a gas are mixed to a holding surface of the holding stage having the holding surface that holds an object to be held; an attraction step of attracting the liquid or the two-fluid supplied to the holding surface after the fluid supply step; a photographing step of photographing the holding surface after the attraction step to acquire an image; and a detection step of detecting, as an abnormality, a region in which the liquid or the two-fluid remains by image processing the image.

2. The diagnosis method of the holding stage according to claim 1, wherein in the photographing step, only a peripheral region of the holding surface other than a central region is photographed.

3. A processing method of an object to be processed, wherein the processing method of the object to be processed has the steps of: a fluid supply step of supplying a liquid or a two-fluid in which a liquid and a gas are mixed to a holding surface of a holding stage having the holding surface; an attraction step of attracting the liquid or the two-fluid supplied to the holding surface after the fluid supply step; a photographing step of photographing the holding surface after the attraction step to acquire an image; a detection step of detecting, as an abnormality, a region in which the liquid or the two-fluid remains by image processing the image; and a processing step of holding an object to be processed on the holding stage free of the abnormality after the detection step and processing the object to be processed by an arbitrary processing unit.

4. The processing method of the object to be processed according to claim 3, wherein in the processing step, the object to be processed is machined. ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​

Images