PROCESSING DEVICE THAT INCLUDES A FEEDING UNIT

Abstract

Machining device (1) comprising: a clamping table (10) for holding a plate-shaped workpiece (100); a machining unit (20) for machining the workpiece (100) held on the clamping table (10); a cassette tray (40) for placing a cassette (45) on it for receiving the workpiece (100); a feeding unit (60) for feeding the workpiece (100) between the cassette (45) placed on the cassette tray (40) and the clamping table (10); and a measuring unit (85) for measuring the thickness of the workpiece (100); wherein the feed unit (60) comprises: a base (66) comprising a non-contact suction holder (67) for expelling air to develop a vacuum for attracting and holding the workpiece (100) under suction without contact with it; and a movement unit (32, 33) for moving the base, and wherein a height of the non-contact suction holder (67) is set according to the thickness of the workpiece (100) which is measured by the measuring unit (85) in order to place the non-contact suction holder (67) at a position which is spaced from an end face (101) of the workpiece (100) by a distance in a predetermined area, while the workpiece (100) is fed by the feeding unit (60).

Description

BACKGROUND OF THE INVENTION AREA OF THE INVENTION

[0001] The present invention relates to a processing device comprising a feeding unit. DESCRIPTION OF THE RELATED STATE OF THE ART

[0002] A device for processing a plate-shaped workpiece, such as a wafer, a resin substrate, or a glass substrate on which semiconductor devices, light-emitting diodes (LEDs), etc., are formed, using a cutting blade or a laser beam is known from the prior art (see, for example, patent JP 5 846 734 B2). The workpiece, which has been held in a cassette, is fed into a processing device by a feeding unit, guided to a clamping table in the processing device, processed by a processing unit in the processing device, guided from the clamping table to a cleaning device or cleaning unit where the workpiece is cleaned, and then returned to the cassette. SUMMARY OF THE INVENTION

[0003] Various feeding units and methods are available for use in machining equipment. One of the feeding methods known from the prior art uses a contactless suction holder which, as disclosed in patent JP 5 846 734 B2, creates a vacuum by expelling air onto a workpiece. However, if, according to the disclosed feeding method, an air discharge side, i.e., an end side, of the contactless suction holder is too far from the workpiece, the contactless suction holder is unable to apply a vacuum to the workpiece.For example, in situations where workpieces of varying thicknesses are available in a range of 3.0 to 5.0 mm, it is likely that the non-contact suction holder will fail to apply sufficient negative pressure to the workpieces that are 5 mm thick when the non-contact suction holder is continuously set to a position for holding workpieces under suction that are 3.0 mm thick, and consequently to unload these workpieces from the machining device.

[0004] It is therefore an object of the present invention to provide a processing device which has a feeding unit which is able to apply a sufficient negative pressure from a non-contact suction holder to a workpiece based on its thickness.

[0005] In accordance with one aspect of the present invention, a machining device is provided comprising a clamping table for holding a plate-shaped workpiece, a machining unit for machining the workpiece held on the clamping table, a cassette tray for placing a cassette on it for receiving the workpiece therein, a feeding unit for feeding the workpiece between the cassette placed on the cassette tray and the clamping table, and a measuring unit for measuring the thickness of the workpiece.The feeding unit includes a base with a non-contact suction holder for expelling air to create a vacuum for attracting and holding the workpiece under suction without contact with it, and a movement unit for moving the base, whereby the height of the non-contact suction holder is adjusted in accordance with the thickness of the workpiece, which is measured by the measuring unit, in order to place the non-contact suction holder at a position that is spaced a certain distance away from an end face of the workpiece within a predetermined area, while the workpiece is fed through the feeding unit.

[0006] The measuring unit can include a counter-pressure sensor or an optical sensor for measuring the thickness of the workpiece without contact with it.

[0007] In accordance with the present invention, the contactless suction holder can apply a sufficient negative pressure to the workpiece in accordance with a thickness of the workpiece.

[0008] The above and other items, features and advantages of the present invention, as well as the manner of its implementation, will best become clearer by studying the following description and attached claims, with reference to the attached drawings, which show some preferred embodiments of the invention, and the invention itself will best be understood by this. BRIEF DESCRIPTION OF THE DRAWINGS Fig. Figure 1 is a perspective view of a structural example of a machining device in accordance with a first embodiment of the present invention; Fig. 2 is a perspective view of a structural example of a feeding unit of the in Fig. 1 illustrated machining device; Fig. 3 is a sectional view illustrating one way in which the feed unit of the in Fig. 1. The illustrated machining device is working; Fig. 4 is a sectional view illustrating how the feed unit of the in Fig. 1. The illustrated machining device is working; Fig. Figure 5 is a view of a structural example of a unit of measurement in Fig. 1 illustrated machining device; and Fig. 6 is a sectional view illustrating how the unit of measurement of the in Fig. 1. The illustrated machining device is in operation. DETAILED EXPLANATION OF THE PREFERRED EXECUTION FORMS

[0009] Preferred embodiments of the present invention are described in detail below with reference to the accompanying drawings. [First embodiment]

[0010] A machining device 1 in accordance with a first embodiment of the present invention is described below with reference to Fig. 1 described. Fig. Figure 1 illustrates a perspective structural example of the machining device 1 in accordance with the first embodiment. Fig. Figure 2 illustrates a structural example of a feeding unit 60 of the in Fig. 1 illustrated machining device 1. The Fig. 3 and Fig. Figure 4 illustrates, on average, one way in which the feed unit 60 of the in Fig. 1. The illustrated machining device is in operation. Fig. Figure 5 illustrates a structural example of a measurement unit 85 of the in Fig. 1 illustrated machining device 1. Fig. Figure 6 illustrates in a sectional view the way in which the measuring unit 85 of the in Fig. The illustrated machining device 1 is in operation. As shown in 1. Fig. As illustrated in Figure 1, the machining device 1 includes a clamping table 10, a pair of machining units 20, a cassette storage unit 40, a loading / unloading unit 50, a cleaning device 55, a feeding unit 60, a measuring unit 85, and a control unit 98. Fig. Figure 1 illustrates the machining device 1 placed in an XYZ coordinate system, which has an X-axis, a Y-axis, and a Z-axis. The X-axis and the Y-axis extend horizontally perpendicular to each other, and the Z-axis extends vertically perpendicular to the X-axis and the Y-axis.

[0011] A workpiece 100, as an object to be machined by the machining device 1 in accordance with the first embodiment, comprises, for example, a semiconductor wafer, an optical component wafer, or the like, which is shaped as a circular plate and made of a base material such as silicon, sapphire, silicon carbide (SiC), or gallium arsenide. As in Fig. As illustrated in Figure 1, the workpiece 100 has several components 103 formed in respective areas that are delimited at a flat end face 101 from this by a grid of projected separation lines 102. According to the present invention, the workpiece 100 can have a packaged substrate, a ceramic plate, a glass plate, or the like, having a rectangular shape with several components encapsulated by resin. Furthermore, according to the present invention, the workpiece 100 can have a plate-shaped layered structure composed of several plate-shaped parts, such as wafers, which are stacked on top of each other or fixed to one another in the thickness direction.

[0012] The clamping table 10 has a frame formed as a circular plate with a defined recess in it, and a suction element frame formed as a circular plate that fits into the recess.

[0013] The suction element of the clamping table 10 is made of a porous ceramic and is held in fluid contact with a vacuum suction source (not shown) via a vacuum suction channel (not shown). The suction element of the clamping table 10 has an upper surface that serves as a holding surface 11 for holding the workpiece 100 placed on it under a suction force, i.e., a negative pressure, which is transmitted from the vacuum suction source via the vacuum suction channel. The holding surface 11 is flush with an upper surface of the frame of the clamping table 10 and extends parallel to an XY plane, which is defined as a horizontal plane by the X-axis and the Y-axis.The clamping table 10 can be moved in one of the X-axis directions as horizontal directions parallel to the X-axis by means of an X-axis motion unit (not shown) and can also be rotated about a central axis by means of a rotation actuator (not shown), which extends vertically, parallel to the Z-axis, which is perpendicular to the holding surface 11.

[0014] As in Fig. As illustrated in Figure 1, each of the machining units 20 includes a cutting blade 21 and a spindle 22, which has one end coupled to the cutting blade 21 and another end coupled to a rotary actuator (not shown). The cutting blade 21 includes an extremely thin cutting stone, essentially shaped as a ring. When the cutting blade 21 is rotated about a central axis parallel to the Y-axis and perpendicular to the X-axis by the rotary actuator coupled to the spindle 22, the cutting blade 21 is lowered to cut into, or slice into, the workpiece 100 held on the clamping table 10. The machining units 20 are movable along the Y-axis by respective Y-axis motion units 32 with respect to the workpiece 100 held on the clamping table 10, and are also movable along the Z-axis by respective Z-axis motion units 33.

[0015] The X-axis motion unit of the machining device 1 moves the clamping table 10 along the X-axis for machining. The Y-axis motion units 32 of the machining device 1 position the respective machining units 20 along the Y-axis. The Z-axis motion units 33 move the respective machining units 20 along the Z-axis for a cut. The X-axis motion unit, the Y-axis motion units 32, and the Z-axis motion units 33 each include a known ball screw rotatable about its central axis, a known stepper motor for rotating the ball screw about its central axis, and known guide rails on which the clamping table 10 or the machining unit 20 is supported for movement along the X-axis, the Y-axis, or the Z-axis.Furthermore, the X-axis motion unit, the Y-axis motion units 32 and the Z-axis motion units 33 each include a position detection unit for detecting the position of the clamping table 10 or the machining unit 20 along the X-axis, the Y-axis or the Z-axis and for outputting the detected position to the control unit 98. As in . Fig. As illustrated in Figure 1, the machining device 1 is a two-spindle dicer, that is, a dual cutting device facing each other with two machining units 20.

[0016] As in Fig. As illustrated in Figure 1, a portal-shaped first support frame 3 is erected from a fixture body 2 and has a pair of vertical columns attached to the fixture body 2 and a horizontal beam connecting the upper end sections of the columns. One of the machining units 20 is attached to one of the columns of the first support frame 3 by one of the Y-axis motion units 32 and one of the Z-axis motion units 33. The other machining unit 20 is attached to the other column of the second support frame 3 by the other Y-axis motion unit 32 and the other Z-axis motion unit 33. The upper end section of the column is connected by the horizontal beam.

[0017] The machining device 1 includes an image acquisition unit 25 for capturing an image of the workpiece 100 held on the holding surface 11 of the clamping table 10. In accordance with the first embodiment, the image acquisition unit 25 is attached to one of the machining units 20 for movement together with it. The image acquisition unit 25 includes a CCD camera for capturing an image of the area to be cut on the workpiece 100 held on the clamping table 10 before the workpiece 100 is cut. The CCD camera performs an image acquisition operation on the workpiece 100 held on the clamping table 10 in order to obtain an image for performing an alignment operation to position the workpiece 100 and the cutting blade 21 relative to each other, and outputs the obtained image to the control unit 98.

[0018] The machining device 1 operates as follows: While the cutting blade 21 is rotated about its central axis by the rotary actuator coupled to the spindle 22, the X-axis motion unit, the Y-axis motion units 32 and the Z-axis motion unit 33 are actuated to move the cutting blade 21 in relation to the workpiece 100 held against the clamping table 10 along one of the projected parting lines 102, causing the cutting blade 21 to cut the workpiece 100 along the projected parting line 102.

[0019] The cassette tray 40 includes a supporting platform for placing a cassette 45, which is a housing containing several workpieces 100. The cassette tray 40 is movable vertically to raise and lower the cassette 45 along the Z-axis. The loading / unloading unit 50 holds a workpiece 100 against a holding surface 51 located below it and guides the workpiece 100 into or out of the cassette 45. The cleaning device 55 cleans a workpiece 100 that has been cut while the workpiece 100 is held by suction against a holding surface 57 of a clamping table 56, which is structurally similar to the clamping table 10.

[0020] The feeding unit 60 feeds a workpiece 100 between the cassette 45 placed on the cassette tray 40 and the clamping tables 10 and 56. In accordance with the Fig. In the first embodiment illustrated in Figure 1, the feeding unit 60 is attached to a portal-shaped second support frame 4, which is located closer to the loading / unloading unit 50 and the clamping tables 10, 55 than the first support frame 3. The second support frame 4 includes a pair of columns 5 and 6, which are attached to the device body 2 and have their respective upper end sections connected to each other by a horizontal support 7. The feeding unit 60 comprises a first feeding unit 60-1 for feeding a workpiece 100 between the loading / unloading unit 50 and the clamping table 10, and a second feeding unit 60-2 for feeding a workpiece 100 between the clamping table 10 and the clamping table 56 of the cleaning device 55. The first feeding unit 60-1 unloads a workpiece 100 to be cut from the loading / unloading unit 50 and loads the workpiece 100 onto the clamping table 10.The second feeding unit 60-2 unloads a workpiece 100 from the clamping table 10 after cutting and loads the workpiece 100 onto the clamping table 56 of the cleaning unit 55. The second feeding unit 60-2 unloads a workpiece 100 that has been cleaned from the clamping table 56 of the cleaning unit 55 and loads the workpiece 100 onto the loading / unloading unit 50.

[0021] As in Fig. As illustrated in Figure 1, the first feeding unit 60-1 and the second feeding unit 60-2 each have a base 61 and a motion unit 62 for moving the base 61. The motion unit 62 includes a unit support arm 63 with a distal end connected to the base 61, a Y-axis motion mechanism 64 for moving the unit support arm 63 along the Y-axis, and a lifting and lowering mechanism 65 attached to the distal end of the unit support arm 63 for moving the base 61 along the Z-axis. The Y-axis motion mechanism 64 is attached to the horizontal support 7 of the second support frame 4. The portal-shaped second support frame 4 extends from the device body 2 and is positioned closer to a loading / unloading area than the support frame 3. The horizontal support 7 connects a pair of columns 5 and 6.The Y-axis motion mechanism 64 comprises a known ball screw extending horizontally along the Y-axis and rotatable about its central axis, a known stepper motor coupled to one end of the ball screw for rotating the ball screw about its central axis, and a known guide rail on which the unit support arm 63 is movably supported for movement along the Y-axis. The unit support arm 63 has a nut (not shown) that engages the ball screw in a threaded connection. The lifting and lowering mechanism 65 includes a known pneumatic cylinder.

[0022] As in the Fig. 2, Fig. 3 and Fig. As illustrated in Figure 4, the base 61 of the first and second feeding units 60-1 and 60-2 each comprises a disc-shaped base plate 66, several non-contact suction cups 67, several supports 68, and several outer-circumference support legs 69. The base plate 66 is attached to the lower end of a rod of the pneumatic cylinder of the lifting and lowering mechanism 65. Therefore, the motion unit 62 moves the base plate 66. In accordance with the Fig. In the first embodiment illustrated in Figure 2, the base 61 includes three non-contact suction cups 67 and three supports 68, respectively, all of which are fixed to the base plate 66 at equal intervals along circumferential directions of the base plate 66.

[0023] Each of the non-contact suction holders 67 comprises a thick, disc-shaped suction holder body 71, a fluid ejector 73 for expelling air 200 from the center of a horizontal, flat lower surface 72 of the suction holder body 71 along the lower surface 72, and a fluid connecting tube 74 that is connected to an upper surface of the suction holder body 71 and is held in fluid communication with the fluid ejector 73. The fluid connecting tube 74 has a hollow, cylindrical structure that extends upward from the center of the upper surface of the suction holder body 71 and is shaped as shown in Fig. Figure 2 illustrates that it is connected to a compressed air supply source 76 via an on / off valve 75.

[0024] As in Fig. As illustrated in Figure 3, the fluid connecting tube 74 extends vertically through a through-hole 77 defined in the base plate 66. The fluid connecting tube 74 includes a radially outwardly projecting bulge 78, the outer circumferential surface of which is positioned between two elements of the respective support 68. The two elements of the respective support 68 are fastened to the base plate 66 by bolts 79, which extend through the base plate 66 and engage in threaded engagement with the support 68, thereby securing the non-contact suction cups 67 to the base plate 66.

[0025] The non-contact suction holder 67 operates as follows: When the compressed air supply source 76 is activated, it supplies pressurized air 200 through the on / off valve 75 and the fluid connection tube 74 to the fluid ejector 73. The fluid ejector 73 expels the supplied air 200 along the lower surface 72 of the suction holder body 71 to create a vacuum in the center of the lower surface 72 in accordance with Bernoulli's principle. This vacuum attracts a workpiece 100 towards the lower surface 72, which serves as the holding surface. As the workpiece 100 approaches the non-contact suction holder 67, the air 200 acting between the lower surface 72 of the suction holder body 71 and the workpiece 100 acts as a repulsive force, preventing the non-contact suction holder 67 from coming into contact with the workpiece 100. Therefore, the contactless suction cup 67 holds, as in the Fig. 3 and Fig. Figure 4 illustrates the workpiece 100 without contact with it under suction.

[0026] The outer circumferential support legs 69 are fixed to the base plate 66. The outer circumferential support legs 69 serve to engage an outer circumferential edge section of the workpiece 100, which is held by the non-contact suction cups 67, in order to restrict the horizontal movement of the workpiece 100. In accordance with the Fig. In the first embodiment illustrated in Figure 2, three outer circumferential support legs 69 are fixed to the base plate 66 at equal intervals along the circumferential directions of the base plate 66. Each of the outer circumferential support legs 69 is arranged between adjacent two of the contactless suction cups 67 along the outer circumferential directions of the base plate 66, closer to an outer circumferential edge of the base plate 66 than the contactless suction cups 67. Each of the outer circumferential support legs 69 is fastened to the base plate 66 by a bolt 81, which extends through the base plate 66 and engages in threaded engagement with the outer circumferential support leg 69, and has a lower surface 82 that is chamfered such that it is gradually inclined upwards towards the center of the base plate 66.The outer circumferential support legs 69 restrict the workpiece 100 in its horizontal movement by keeping the inclined lower surfaces 82 in contact with the outer circumferential edge section of the workpiece 100, while the non-contact suction holders 67 attract the workpiece 100 by suction action and without contact with it.

[0027] In accordance with the first embodiment, the measuring unit 85 is as shown in Fig. Figure 1 indirectly illustrates the movement of the measuring unit 85 along the Y-axis and Z-axis, respectively, by means of the Y-axis motion unit 32 and the Z-axis motion unit 33. The measuring unit 85 can also be directly attached to one of the processing units 20.

[0028] In accordance with the first embodiment, the measuring unit 85 includes a back pressure sensor. As in the Fig. 5 and Fig. As illustrated in Figure 6, the measuring unit 85 includes an ejection nozzle 86 for ejecting 300 mm of air (see Figure 6). Fig. 6) through an ejection opening 87 in the direction of the holding surface 51 of the loading / unloading unit 50 and the workpiece 100, which is held on the holding surface 51. As in Fig. As illustrated in Figure 5, the ejection nozzle 86 is attached to a piston rod 89 of a pneumatic cylinder 88, which is attached to the image acquisition unit 25, by means of a limit switch 97 described below.

[0029] The discharge nozzle 86 is kept in fluid communication with an air supply source 92 via a first passage 91. The air supply source 92 is also kept in fluid communication with a second passage 93, which is vented to the ambient air through a throttle valve 94 at the distal end of the second passage 93. The air supply source 92 carries air 300 (see Fig. 6) to the first passage 91 and the second passage 93 in a suitable ratio. The air 300 flowing through the first passage 91 is supplied to the discharge nozzle 86.

[0030] A differential pressure sensor 95 is connected between the first passage 91 and the second passage 93. The differential pressure sensor 95 has a diaphragm 96 and is electrically connected to the control unit 98. The diaphragm 96 can be displaced by a distance that depends on the difference between the air pressure in the first passage 91 and the air pressure in the second passage 93. The differential pressure sensor 95 outputs a voltage value to the control unit 98, which represents the distance by which the diaphragm 96 is displaced.

[0031] When the air supply source 92 supplies air 300 to the first passage 91 and the second passage 93, the discharge nozzle 86 expels the air 300 through the discharge opening 87. If there is no workpiece 100 in front of the air 300 being expelled from the discharge opening 87 of the discharge nozzle 86, the voltage value output by the differential pressure sensor 95 can be set to 1 V by adjusting the throttle valve 94. A workpiece 100 that is in front of the air 300 being expelled from the discharge opening 87, but is, for example, 5 mm or more away from the discharge opening 87, is considered not to be present.

[0032] The ejection nozzle 86 is aligned so that the ejection opening 87 at its distal end faces the workpiece 100 on the loading / unloading unit 50. The pneumatic cylinder 88 can be actuated to lower the piston rod 89, thus moving the ejection opening 87 towards the workpiece 100.

[0033] The limit switch 97 (see Fig. 5), by which the ejection nozzle 86 is attached to the piston rod 89, is located below and connected to the lower end of the piston rod 89. The limit switch 97 limits the downward movement of the ejection nozzle 86 and detects when the ejection nozzle 86 is in an operating position. The limit switch 97, which is electrically connected to the control unit 98, detects whether the ejection nozzle 86 is in the operating position or a rest position and sends a signal to the control unit 98 indicating the detected result.

[0034] In the event that there is no obstacle, for example no workpiece 100, in front of the air 300 expelled from the ejection opening 87 of the ejection nozzle 86, the pressure in the first pass 91 and the pressure in the second pass 93 are in equilibrium, since both the first pass 91 and the second pass 93 are vented to the environment, so that the diaphragm 96 of the differential pressure sensor 95 is in an equilibrium position. Since the voltage value output by the differential pressure sensor 95 is set to 1 volt with the diaphragm 96 in the equilibrium position, the differential pressure sensor 95 outputs a voltage of 1 volt at this time.

[0035] In the event that an obstacle, such as a workpiece 100, is present in front of the air 300 ejected from the ejection opening 87 of the ejection nozzle 86, the ejection opening 87 is covered by the workpiece 100, which changes the pressure in the first pass 91 to displace the diaphragm 96 from the equilibrium position, so that the differential pressure sensor 95 outputs a voltage value which corresponds to the distance between the ejection opening 87 and the workpiece 100.

[0036] The control unit 98 controls the operation of the components of the machining device 1, enabling the machining device 1 to perform a machining operation with the machining units 20, a feeding operation with the feeding unit 60, a measuring operation with the measuring unit 85, etc. In accordance with the first embodiment, the control unit 98 includes a computer system with an arithmetic processing unit comprising a microprocessor, such as a central processing unit (CPU), a memory device comprising memory, such as read-only memory (ROM) or random access memory (RAM), and an input / output interface.The arithmetic processing unit of the control unit 98 executes a processing sequence in accordance with computer programs stored in the memory device and generates control signals to control the processing device 1 and outputs these to the components of the processing device via the input / output interface.

[0037] The control unit 98 reads the voltage value output by the differential pressure sensor 95 and controls the Z-axis motion unit 32 and the pneumatic cylinder 88 in accordance with the read voltage value to prevent the ejection nozzle 86 from striking the holding surface 51 of the loading / unloading unit 50 or the end face 101 of the workpiece 100 held on the holding surface 51. The control unit 98 includes a memory 99 that, for example, stores data in advance relating the distance values ​​from the ejection opening 87 of the ejection nozzle 86 to the holding surface 51 of the loading / unloading unit 50 or to the end face 101 of the workpiece 100 held on the holding surface 51, and voltage values ​​output by the differential pressure sensor 95. The memory 99 is implemented by the memory device of the computer system belonging to the control unit 98.

[0038] Therefore, the control unit 98 can determine the distance between the ejection opening 87 of the ejection nozzle 86 and the holding surface 51 of the loading / unloading unit 50 or the end face 101 of the workpiece 100 held on the holding surface 51 based on the voltage value output by the differential pressure sensor 95 and the relationship data stored in the memory 99. If the voltage value output by the differential pressure sensor 95 is, for example, 5 V, the control unit 98 determines the distance between the ejection opening 87 and the holding surface 51 of the loading / unloading unit 50 or the end face 101 of the workpiece 100 held on the holding surface 51 to be, for example, 100 µm.

[0039] The following describes the operation of the machining device 1 in accordance with the first embodiment, with reference to the drawings. The control unit 98 of the machining device 1 controls the loading / unloading unit 50 to hold a workpiece 100 to be cut against its holding surface 51 in the cassette 45, to remove the workpiece 100 from the cassette 45, and to temporarily stop the loading / unloading unit 50.

[0040] As indicated by the solid lines in Fig. As indicated in Figure 6, the control unit 98 controls the Z-axis motion unit 33 to bring the ejection opening 87 of the ejection nozzle 86 sufficiently close to the end face 101 of the workpiece 100 on the holding surface 51 of the loading / unloading unit 50, which has been temporarily stopped. At this point, the control unit 98 determines the position of the ejection opening 87 along the Z-axis based on position information received from the Z-axis motion unit 33 and the air cylinder 88. The control unit 98 then controls the measuring unit 85 to expel the air 300 from the ejection opening 87 to the workpiece 100 and determines the distance between the ejection opening 87 and the end face 101 of the workpiece 100 based on the relationship data stored in the memory 99.The control unit 98 determines the position of the end face 101 of the workpiece 100 along the Z-axis based on the position of the ejection opening 87 along the Z-axis and the distance between the ejection opening 87 and the end face 101 of the workpiece 100.

[0041] As indicated by the dashed double dot lines in Fig. As indicated in Figure 6, the control unit 98 controls the Z-axis motion unit 33 to bring the ejection opening 87 sufficiently close to an exposed section of the holding surface 51 of the loading / unloading unit 50, which has been temporarily stopped. The control unit 98 then performs a process similar to the above process of determining the position of the end face 101 of the workpiece 100, which is held against the holding surface 51 of the temporarily stopped loading / unloading unit 50, along the Z-axis, thus determining the position of the exposed section of the holding surface 51 along the Z-axis.

[0042] The control unit 98 controls the measuring unit 85 to determine the thickness of the workpiece 100 by subtracting the position of the exposed section of the holding surface 51 along the Z-axis from the position of the end face 101 of the workpiece 100, which is held on the holding surface 51 of the loading / unloading unit 50, along the Z-axis. The thickness of the workpiece 100 represents the height of the end face 101 of the workpiece 100 from the holding surface 51 of the loading / unloading unit 50. In this way, the measuring unit 85 measures the thickness, i.e., the height, of the workpiece 100 held on the holding surface 51 of the loading / unloading unit 50, without any part of the measuring unit 85 touching the workpiece 100.

[0043] The control unit 98 controls the feed unit 60 to cause the lifting and lowering mechanism 65 of the motion unit 62 to adjust the height of the lower surface 72, i.e., a holding surface, of the non-contact suction holder 67 according to the thickness of the workpiece 100 as measured by the measuring unit 85. This positions the lower surface 72 at a distance from the end face 101, i.e., a held surface, of the workpiece 100 within a predetermined range. The predetermined range refers to a range of distances between the lower surface 72 of the non-contact suction holder 67 and the end face 101 of the workpiece 100, such that the non-contact suction holder 67 can apply sufficient negative pressure to the workpiece 100 within this range to hold it under constant suction.In other words, the control unit 98 controls the feed unit 60 to adjust the height of the lower surface 72 of the non-contact suction holder 67 in accordance with the thickness of the workpiece 100, which is measured by the measuring unit 85, to a height from the holding surface 51, on which the workpiece 100 is held, which is greater than the predetermined range by the thickness of the workpiece 100.

[0044] In accordance with the first embodiment, the control unit 98 in particular controls the movement unit 62 to determine the height that is in Fig. 3 as 111 or in Fig. 4, designated as 112, the lower surface 72 of the contactless suction holder 67 is to be adjusted from the holding surface 51 of the loading / unloading unit 50 to a height that is represented by the sum of the thickness of the workpiece 100, as measured by the measuring unit 85, and the predetermined range. In particular, in the case where the thickness of the workpiece 100, as in Fig. As illustrated in Figure 3, the control unit 98 controls the motion unit 62 to adjust the height 111 of the lower surface 72 of the contactless suction holder 67 from the holding surface 51 of the loading / unloading unit 50 to a value corresponding to the relatively small thickness of the workpiece 100. In the case that the thickness of the workpiece 100, as in Figure 3, is relatively small, the control unit 98 controls the motion unit 62 to adjust the height 111 of the lower surface 72 of the contactless suction holder 67 from the holding surface 51 of the loading / unloading unit 50 to a value corresponding to the relatively small thickness of the workpiece 100. Fig.As illustrated in Figure 4, which is relatively large, the control unit 98, on the other hand, controls the motion unit 62 to adjust the height 111 of the lower surface 72 of the contactless suction holder 67 from the holding surface 51 of the loading / unloading unit 50 to a value which corresponds to the relatively large thickness of the workpiece 100.

[0045] After the control unit 98 has set the height of the lower surface 72 of the contactless suction holder 67, it controls the contactless suction holder 67 to expel air 200 from the fluid ejector 73 along the lower surface 72 of the suction holder body 71, thus creating a vacuum on the lower surface 72 in accordance with Bernoulli's principle. This vacuum holds the workpiece 100 by suction without contact. Once the contactless suction holder 67 has held the workpiece 100 under suction, the control unit 98 controls the motion unit 62 to guide the workpiece 100, held by the contactless suction holder 67, onto the holding surface 11 of the clamping table 10.The control unit 98 then controls the contactless suction holder 67 to interrupt the expulsion of air 200 and holding of the workpiece 100 under suction, thereby placing the workpiece 100 on the holding surface 11 of the clamping table 10.

[0046] In accordance with the first embodiment, the processing unit 20 includes a cutting unit. The thickness of the workpiece 100 does not change significantly when it is cut. Therefore, when the non-contact suction holder 67 holds the workpiece 100 after it has been cut or cleaned, the control unit 98 does not need to remeasure the thickness of the workpiece 100 and can adjust the height of the lower surface 72 of the non-contact suction holder 67 according to the thickness of the workpiece 100 as measured when the workpiece 100 was removed from the cassette 45 by the loading / unloading unit 50 before cutting.In particular, to hold the workpiece 100 under suction on the holding surfaces 11 and 57 of the clamping tables 10 and 56 after it has been cut or cleaned, the control unit 98 adjusts the height of the lower surface 72 of the contactless suction holder 67 from the holding surfaces 11 and 57 of the clamping tables 10 and 56 to a height which is represented by the sum of the thickness of the workpiece 100, which is measured by the measuring unit 85 before the workpiece 100 is cut, and the predetermined area.

[0047] With the processing device 1 constructed in accordance with the first embodiment, the contactless suction holder 67 can apply sufficient negative pressure to the workpiece 100 in accordance with the thickness of the workpiece 100 and can feed the workpiece 100 while holding it under constant suction force, even if a workpiece 100 removed from the cassette 45 has a different thickness, since the measuring unit 85 measures the thickness, i.e. the height, of the workpiece 100 and the movement unit 62 adjusts the height of the lower surface 72 of the contactless suction holder 67 in accordance with the measured thickness.

[0048] Since the measuring unit 85 of the processing device 1, in accordance with the first embodiment, also has a counter-pressure sensor, it can measure the thickness, i.e., the height, of the workpiece 100 without touching it. Consequently, the processing device 1, in accordance with the first embodiment, is able to measure the thickness of the workpiece 100, hold the workpiece 100 under suction, and feed the workpiece 100 without contact with it, thus maintaining the end face 101 of the workpiece 100 in good quality. [Second embodiment]

[0049] A machining device 1 according to a second embodiment of the present invention is described below. The machining device 1 according to the second embodiment differs from the machining device 1 according to the first embodiment in that the measuring unit 85 has an optical sensor instead of a back pressure sensor. Other details of the machining device 1 according to the second embodiment are identical to those of the machining device 1 according to the first embodiment. These identical details are identified by identical reference numerals and are omitted from the description.

[0050] The measuring unit 85 according to the second embodiment includes an irradiator for applying a laser beam to the holding surface 51 of the loading / unloading unit 50 or to the end face 101 of the workpiece 100 held on the holding surface 51, and a beam detector for detecting a beam reflected from the holding surface 51 or the end face 101 that has been irradiated with the laser beam. The measuring unit 85 according to the second embodiment determines the distance from the measuring unit 85 to the holding surface 51 of the loading / unloading unit 50 or the end face 101 of the workpiece 100 held on the holding surface 51 based on the beam reflected from the holding surface 51 or the end face 101 and detected by the beam detector. The measuring unit 85 according to the second embodiment incorporates other processing details that are identical to those of the measuring unit 85 according to the first embodiment.Consequently, in accordance with the second embodiment, the measuring unit 85 can measure the thickness, i.e., the height, of the workpiece 100 obtained on the holding surface 51 of the loading / unloading unit 50 without contact with it, i.e., without any parts of the measuring unit 85 touching the workpiece 100.

[0051] Insofar as the processing device 1 in accordance with the second embodiment differs from the processing device 1 in accordance with the first embodiment in that the measuring unit 85 has an optical sensor instead of a back pressure sensor, the processing device 1 in accordance with the second embodiment offers the same advantages as the processing device 1 in accordance with the first embodiment. [Modification]

[0052] A machining device 1 in accordance with a modification of the first and second embodiments is described below. The machining device 1 in accordance with the modification differs from the machining device 1 in accordance with the first and second embodiments in that each of the machining units 20 is different, i.e., it is not a cutting unit. Other details of the machining device in accordance with the modification are identical to those of the machining device 1 in accordance with the first and second embodiments. These identical details are identified by identical reference numerals and are omitted from the description.

[0053] In accordance with the modification, each of the processing units 20 can include a laser processing unit, a cleaning unit, a grinding unit, or the like. If the processing units 20 include a laser processing unit for applying a laser beam to the workpiece 100 to process it, or a cleaning unit for cleaning the workpiece 100, the thickness of the workpiece 100 does not change significantly when processed by the laser beam, as is the case in the first and second embodiments. Therefore, to hold the workpiece 100 after it has been processed or cleaned with the laser beam, the control unit 98 adjusts the height of the lower surface 72 of the non-contact suction holder 67 according to the thickness of the workpiece 100, which is measured when the workpiece 100 is removed from the cassette 45 before being cut by the loading / unloading unit 50.

[0054] In the case that the machining unit 20 has a grinding unit for grinding the workpiece 100 with a grinding wheel, the thickness of the workpiece 100 changes due to the grinding of material from the workpiece 100. To hold the workpiece 100 after it has been machined or cleaned with the grinding wheel, the control unit 98 therefore controls the measuring unit 85, for example, to remeasure the thickness of the ground workpiece 100 on the holding surface 11 of the clamping table 10, and then controls the motion unit 62 to adjust the height of the lower surface 72 of the contactless suction holder 67 according to the measured thickness of the ground workpiece 100.

[0055] Since the machining device 1 in accordance with the modification differs from the machining device 1 in accordance with the first and second embodiments in that the machining unit 20 is changed, the machining device 1 in accordance with the modification offers the same advantages as those of the machining device 1 in accordance with the first and second embodiments.

[0056] The present invention is not limited to the preferred embodiments and modifications described above. Numerous changes and modifications can be made to it without departing from the scope of the invention. In accordance with the above embodiments, the measuring unit includes a back pressure sensor or an optical sensor. However, in accordance with the present invention, the measuring unit is not limited to the sensors and can include a sensor of any type, provided that it is capable of measuring the thickness of a workpiece held on the holding surface of the loading / unloading unit. The measuring unit 85 can be arranged independently of the image acquisition unit 25 and can be attached to the lifting and lowering mechanism 65.In accordance with this modification, the measuring unit 85 is arranged above the loading / unloading unit 50, which holds a workpiece 100 unloaded from the cassette 45, and can be raised and lowered relative to the holding surface 51 of the loading / unloading unit 50. The measuring unit 85 detects the holding surface 51 or the end face 101 of the workpiece 100 while calculating the position, i.e., the height, of its own sensor.

Claims

[1] Machining device (1) comprising: a clamping table (10) for holding a plate-shaped workpiece (100); a machining unit (20) for machining the workpiece (100) held on the clamping table (10); a cassette tray (40) for placing a cassette (45) on it for receiving the workpiece (100); a feeding unit (60) for feeding the workpiece (100) between the cassette (45) placed on the cassette tray (40) and the clamping table (10); and a measuring unit (85) for measuring the thickness of the workpiece (100); wherein the feed unit (60) comprises: a base (66) comprising a non-contact suction holder (67) for expelling air to develop a vacuum for attracting and holding the workpiece (100) under suction without contact with it; and a movement unit (32, 33) for moving the base, and wherein a height of the non-contact suction holder (67) is set according to the thickness of the workpiece (100) which is measured by the measuring unit (85) in order to place the non-contact suction holder (67) at a position which is spaced from an end face (101) of the workpiece (100) by a distance in a predetermined area, while the workpiece (100) is fed by the feeding unit (60). [2] Machining device (1) according to claim 1, wherein the measuring unit (85) has a counter-pressure sensor or an optical sensor for measuring the thickness of the workpiece (100) without contact with it.

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