Cutting device

Abstract

Cutting device (2) for cutting a workpiece (11), comprising: a clamping table (10) with a holding surface (10a) for holding the workpiece (11) on it; a cutting unit (20a, 20b) comprising a spindle (64) with a cutting blade (58) mounted at its distal end for cutting the workpiece (11) held on the holding surface (10a); an image acquisition unit (94) for capturing an image of an outer circumferential section of the cutting blade (58) mounted on the cutting unit (20a, 20b); and a determination section (132) for determining an orientation of the cutting blade (58), wherein the outer circumferential section of the cutting blade (58) has several projections (60) each having a first surface (60a) for scraping chips from the workpiece (11) when the cutting blade (58) cuts the workpiece (11), and a second surface (60b) connected to the first surface (60a), and wherein the determining section (132) determines the orientation of the cutting blade (58) mounted on the cutting unit (20a, 20b) in accordance with an image taken by the image acquisition unit (94) of the projections (60).

Description

AREA OF INVENTION

[0001] The present invention relates to a cutting device for cutting a workpiece. DESCRIPTION OF THE RELATED STATE OF THE ART

[0002] Wafers with multiple integrated components are divided into several individual pieces, each serving as a component chip and containing the respective component. Alternatively, multiple component chips are attached to a base substrate and encapsulated with a resin, i.e., a molding resin, to create a package substrate. This package substrate is then divided into several individual pieces, each serving as a package component, containing the respective package component chips. The component chips and package components are incorporated into a wide variety of electronic devices, such as mobile phones and personal computers.

[0003] Cutting devices are commonly used to divide workpieces such as wafers and housing substrates. A cutting device includes a clamping table for holding a workpiece and a cutting unit for cutting the workpiece on the clamping table. The cutting unit contains a rotating spindle, and an annular cutting blade is mounted at the distal end of the spindle. The cutting device operates as follows: The clamping table holds the workpiece and is then moved relative to the cutting unit, that is, fed towards the cutting unit for machining, while the cutting blade is rotated by the spindle around its central axis. The cutting blade cuts into the workpiece, dividing it into individual pieces.

[0004] The structure, material, and other details of the cutting blade are selected depending on the material, properties, etc., of the workpiece to be cut. For example, if the workpiece to be cut and divided by the cutting blade is a slab made of raw ceramic, the cutting blade has several sawtooth-shaped projections on its outer circumferential edge (see patent application JP H04-179505A).

[0005] Another cutting blade is disclosed in patent application JP 2021 - 79 514 A, and a cutting machine with a monitoring unit for monitoring a cutting edge of a cutting blade is disclosed in patent application US 2021 / 0 229 186 A1. SUMMARY OF THE INVENTION

[0006] To cut a workpiece with a cutting blade having several sawtooth-shaped projections, the cutting blade is mounted on a cutting unit in a predetermined orientation. In particular, each of the sawtooth-shaped projections has a rake face and a clearance face, and the cutting blade is mounted on the distal end of a rotatable spindle such that the rake face is positioned in front of the clearance face in the direction of rotation of the cutting blade.

[0007] When the operator is required to install the cutting blade on the cutting unit, they must visually identify the orientation of small, sawtooth-shaped protrusions and mount the cutting blade in a predetermined orientation, taking into account the direction in which the clamping table will be fed to the cutting unit for machining. Given these requirements, it is highly likely that the operator will install the cutting blade in an incorrect orientation. If the incorrectly installed cutting blade is used to continuously cut the workpiece, the workpiece will not be cut as intended by the operator, potentially resulting in machining defects.

[0008] A device can be used to cut a workpiece that is essentially a twin-spindle cutting device, comprising a pair of cutting units, each with a pair of cutting blades mounted on them in a mutually facing relationship. With this twin-spindle cutting device, the orientations of the cutting blades relative to the respective spindles on the cutting units are different. Therefore, the operator is prone to misjudging the correct orientation of the cutting blades and using them incorrectly.

[0009] The present invention was developed in light of the above difficulties. It is an object of the present invention to provide a cutting device capable of preventing machining errors that occur due to an incorrectly installed cutting blade.

[0010] In accordance with one aspect of the present invention, a cutting device for cutting a workpiece is provided, comprising a clamping table with a holding surface for holding the workpiece thereon, a cutting unit comprising a spindle with a cutting blade mounted at a distal end thereof for cutting the workpiece held on the holding surface, an image acquisition unit for capturing an image of an outer circumferential section of the cutting blade mounted on the cutting unit, and a determination section for determining the orientation of the cutting blade.In the cutting device, the outer circumferential section of the cutting blade includes several projections, each having a first surface for separating chips from the workpiece when the cutting blade cuts the workpiece, and a second surface connected to the first surface, and the determining section determines the orientation of the cutting blade mounted on the cutting unit in accordance with an image taken of the projections by the image acquisition unit.

[0011] Preferably, the determining section determines the orientation of the cutting blade in accordance with the dimensions of the first and second surfaces of the projections in their image, which has been captured by the image acquisition unit. Alternatively, preferably, the determining section determines the orientation of the cutting blade in accordance with the inclinations of the first and second surfaces of the projections in their image, which has been captured by the image acquisition unit. Alternatively, preferably, the determining section determines the orientation of the cutting blade in accordance with the result of a comparison between the image of the projections captured by the image acquisition unit and a reference image.

[0012] The cutting device, in accordance with the above aspect of the present invention, is capable of determining the orientation of the cutting blade in accordance with the image of the projections captured by the image acquisition unit. This prevents the workpiece from being continuously cut by a cutting blade mounted on the cutting unit in an incorrect orientation, thereby preventing machining defects caused by the incorrectly oriented cutting blade.

[0013] The above and other items, features and advantages of the present invention and its implementation will best become clearer by studying the following description and attached claims, with reference to the attached drawings which show a preferred embodiment 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 cutting device in accordance with a preferred embodiment of the present invention; Fig. 2A is a front view of a cutting blade of the cutting device; Fig. 2B is an enlarged partial view from the front of an outer circumferential section of the cutting blade; Fig. Figure 3 is an enlarged, perspective exploded view of a cutting unit of the cutting device; Fig. Figure 4 is a partial sectional view from the front of an image acquisition unit of the cutting device; Fig. 5A is a side view of a first cutting unit; Fig. 5B is a side view of a second cutting unit; Fig. Figure 6 is a block diagram of a cutting device control system; Fig. 7A is a diagram illustrating a captured image; Fig. 7B is a diagram illustrating a combined image; Fig. 8A is a diagram illustrating a section of the combined image where a cutting edge position detection operation is to be performed; Fig. 8B is a diagram illustrating a section of the combined image on which a capture area adjustment operation is to be performed; Fig. 8C is a diagram illustrating a section of the combined image on which an extremum determination process is to be performed; Fig. Figure 9 is a diagram illustrating a section of the combined image on which a dimension calculation operation is to be performed; Fig. 10A is a diagram illustrating a combined image; Fig. 10B is a diagram illustrating an edge detection image; Fig. Figure 10C is a diagram illustrating an edge detection image on which a straight line extraction operation is to be performed; Fig. 11A is a diagram illustrating a reference image; Fig. Figure 11B is a diagram illustrating a captured image of a protrusion of a cutting blade that is properly installed; and Fig. Figure 11C is a diagram illustrating a captured image of a protrusion of a cutting blade that is incorrectly installed. DETAILED EXPLANATION OF THE PREFERRED FORM OF EXECUTION

[0014] A cutting device in accordance with a preferred embodiment of the present invention is described in detail below with reference to the accompanying drawings. First, structural details of the cutting device in accordance with the present embodiment are described below. Fig. Figure 1 illustrates the cutting device labeled 2 for cutting a workpiece 11 in perspective. Fig. Figure 1 illustrates the cutting device 2 with respect to a three-dimensional coordinate system with an X-axis, a Y-axis, and a Z-axis. X-axis directions, that is, machining feed directions, first horizontal directions, or forward and backward directions along the X-axis, and Y-axis directions, that is, positioning directions, second horizontal directions, or directions to the left and right along the Y-axis, are perpendicular to each other. Z-axis directions, that is, vertical directions, upward and downward directions, or height-like directions along the Z-axis, are perpendicular to the X-axis and Y-axis directions. Coordinates described later with respect to the cutting device 2 belong to this three-dimensional coordinate system.

[0015] As in Fig. As illustrated in Figure 1, the cutting device 2 includes a base 4, which is designed as a rectangular cuboid and supports and accommodates various components of the cutting device 2. The base 4 has a rectangular opening 4a, defined in a corner of a front end section and open upwards in an upper surface of the base 4. The opening 4a accommodates a cassette support table 6, which can be raised and lowered by a lifting and lowering mechanism (not illustrated). The cassette support table 6 can then support a cassette 8, which holds several workpieces 11 that are to be processed, i.e., cut, by the cutting device 2. Fig. 1 The outline of the cassette is indicated by the lines marked with two dots and a dash.

[0016] Each of the workpieces 11, for example, is a disk-shaped wafer made of a semiconductor material, such as monocrystalline silicon, and has a front and a back face that are essentially parallel to each other. The workpiece 11 has several rectangular regions delimited by several streets or projected dividing lines arranged crosswise in a lattice structure. Several components are mounted on the front face of the workpiece 11, illustrated as facing downwards, in the respective regions delimited by the streets. The components can be, for example, integrated circuits (ICs), large-area integration circuits (LSI), light-emitting diodes (LEDs), microelectromechanical systems (MEMS) devices, or similar.

[0017] A strip, that is, a separating strip, 13, is attached to the downward-facing rear side of the workpiece 11. The strip 13 comprises a circular film, that is, a base layer, which has a larger diameter than the workpiece 11, and an adhesive layer, that is, an adhesive layer, on the base layer. The base layer is made of a resin, such as polyolefin, polyvinyl chloride, or polyethylene terephthalate, whereas the adhesive layer is made of an epoxy-based, acrylic-based, or rubber-based adhesive. Alternatively, the adhesive layer can be made of an ultraviolet-curable resin that can be cured upon exposure to ultraviolet radiation.

[0018] The strip 13 has an outer circumferential section that is attached to an annular frame 15 made of a metallic material or similar. The frame 15 has a circular opening defined centrally within it and extending vertically or in the thickness direction through it. The diameter of the opening in the frame 15 is larger than that of the workpiece 11, so that the workpiece 11 is positioned within the frame 15. When a central section of the strip 13 is attached to the workpiece 11 and the outer circumferential section of the strip 13 is attached to the frame 15, the workpiece 11 is supported by the strip 13 on the frame 15.

[0019] The workpieces 11 held in cassette 8 are supported by respective belts 13 on respective annular frames 15. The workpieces 11, supported by the annular frames 15 via the belts 13, are removed from cassette 8 and cut by the cutting device 2. The cutting device 2 cuts each workpiece 11 along the paths into multiple component chips, each containing components. The workpiece 11 is not limited to any specific types, materials, shapes, structures, sizes, etc. For example, the workpiece 11 can be a substrate or a wafer made of a semiconductor other than silicon, such as gallium arsenide (GaAs), indium phosphite (InP), gallium nitride (GaN), or silicon carbide (SiC), glass, sapphire, ceramic, resin, metal, or the like. The components are not limited to a specific type, number, shape, structure, size, layout, etc.The workpiece 11 can be free of components. The workpiece 11 can be a package substrate, such as a Chip Sized Package Substrate (CSP) or a Quad Flat Non-Leaded Package Substrate (QFN). For example, a package substrate is manufactured by encapsulating several component chips mounted on a base substrate with a resin layer, i.e., a molded resin layer. The package substrate is then divided into individual pieces as several packing units, each containing the respective component chips.

[0020] The base 4 also has a defined, elongated, rectangular opening 4b along the opening 4a and opening upwards in the upper surface of the base 4. The opening 4b has a longitudinal axis extending in the X-axis directions. The opening 4b accommodates a clamping table, i.e., a holding table, 10, for holding a workpiece 11. The clamping table 10 has an upper surface that lies flat, essentially parallel to a horizontal plane, i.e., an XY plane extending along the X and Y axes. The upper surface of the clamping table 10 serves as a holding surface 10a for holding the workpiece 11. The holding surface 10a is in fluid communication with a suction source (not illustrated), such as an ejector, via a suction channel (not illustrated) defined in the clamping table 10, a valve (not illustrated), etc.

[0021] The clamping table 10 is combined with a motion mechanism 12, which is arranged in the base 4 for moving the clamping table 10 along the X-axis directions. The motion mechanism 12 is a ball screw-type motion mechanism and includes an X-axis ball screw (not illustrated) extending along the X-axis directions and an X-axis stepper motor (not illustrated) for rotating the X-axis ball screw about its horizontal central axis parallel to the X-axis. The motion mechanism 12 has a table cover 14, which is designed as a flat plate surrounding the clamping table 10. A bellows-like, dustproof, waterproof cover 16, which is flexibly expandable and retractable along the X-axis directions, is arranged in the opening 4b in front of and behind the table cover 14.The table cover 14 and the dustproof, waterproof cover 16, which is arranged in the opening 4b, cover the components, i.e. the X-axis ball screw, the X-axis stepper motor, etc. of the motion mechanism 12.

[0022] The clamping table 10 is connected to a rotary actuator (not illustrated), such as an electric motor, for rotating the clamping table 10 about its vertical central axis, which is essentially parallel to the Z-axis. The clamping table 10 is surrounded by several clamps 18 attached to the table cover 14 for gripping and securing the frame 15 that supports the workpiece 11 on the clamping table 10.

[0023] A feeding mechanism (not illustrated) is located at base 4 in the vicinity of openings 4a and 4b for conveying a workpiece 11 between cassette 8 and clamping table 10. The feeding mechanism removes the workpiece 11 from cassette 8 and feeds it to the clamping table 10, where the workpiece 11, with the intervening belt 13, is positioned on the holding surface 10a. The frame 15 is then gripped by the clamps 18 and secured in place. A suction force, i.e., a negative pressure generated and transmitted by the suction source, is then applied to the holding surface 10a through the valve and suction channel, thus holding the workpiece 11 against the clamping table 10 under suction.

[0024] A cutting unit, that is, a first cutting unit 20a, and a cutting unit, that is, a second cutting unit 20b, are arranged above the clamping table 10 and are supported by a portal-shaped support structure 22. The support structure 22, which supports the cutting units 20a and 20b, is located on the upper surface of the base 4 and extends over and above the opening 4b. The support structure 22 supports a pair of motion mechanisms 24a and 24b on its front surface on opposite side sections. Motion mechanism 24a is a ball screw motion mechanism for moving the cutting unit 20a along the Y-axis and the Z-axis directions. Motion mechanism 24b is a ball screw motion mechanism for moving the cutting unit 20b along the Y-axis and the Z-axis directions.The motion mechanisms 24a and 24b are mounted on a pair of Y-axis guide rails 26, which are attached to the front surface of the support structure 22 and extend along the Y-axis directions.

[0025] The motion mechanism 24a includes a flat, movable Y-axis plate 28a, which is slidably mounted on the Y-axis guide rails 26. A nut (not illustrated) is mounted on a rear surface of the movable Y-axis plate 28a. The nut engages with a Y-axis ball screw 30a, which is located between the Y-axis guide rails 26 and extends substantially parallel to them. The Y-axis ball screw 30a has one end coupled to a Y-axis stepper motor 32 to rotate the Y-axis ball screw 30a about its horizontal central axis. When the Y-axis stepper motor 32 is powered, it rotates the Y-axis ball screw 30a about its horizontal central axis, causing the nut to move the movable Y-axis plate 28a in one of the Y-axis directions along the Y-axis guide rails 26.A pair of Z-axis guide rails 34a is fixedly mounted to an end face, i.e., a front surface, of the movable Y-axis plate 28a and extends along the Z-axis directions. A flat, movable Z-axis plate 36a is slidably mounted on the Z-axis guide rails 34a. A nut (not illustrated) is mounted to a rear surface, i.e., a back surface, of the movable Z-axis plate 36a. The nut engages with a Z-axis ball screw 38a, which is arranged between the Z-axis guide rails 34a and extends substantially parallel to them. The Z-axis ball screw 38a has one end coupled to a Z-axis stepper motor 40a for rotating the Z-axis ball screw 38a about its vertical central axis.When the Z-axis stepper motor 40a is powered, it rotates the Z-axis ball screw 38a around its vertical central axis, causing the nut to move the movable Z-axis plate 36a along the Z-axis guide rails 34a in one of the Z-axis directions.

[0026] Similarly, the motion mechanism 24b includes a flat, movable Y-axis plate 28b, which is slidably mounted on the Y-axis guide rails 26. A nut (not illustrated) is mounted on a rear surface of the movable Y-axis plate 28b. The nut engages with a Y-axis ball screw 30b in threaded engagement, which is located between the Y-axis guide rails 26 and extends substantially parallel to them. The Y-axis ball screw 30b has one end coupled to a Y-axis stepper motor (not illustrated) to rotate the Y-axis ball screw 30b about its horizontal central axis. When the Y-axis stepper motor is powered, it rotates the Y-axis ball screw 30b about its horizontal central axis, causing the nut to move the movable Y-axis plate 28b along the Y-axis guide rails 26 in one of the Y-axis directions.A pair of Z-axis guide rails 34b is fixedly mounted to an end face, i.e., a front surface, of the movable Y-axis plate 28b and extends along the Z-axis directions. A flat, movable Z-axis plate 36b is slidably mounted on the Z-axis guide rails 34b. A nut (not illustrated) is mounted on a rear surface, i.e., a back surface, of the movable Z-axis plate 36b. The nut engages with a Z-axis ball screw 38b in threaded engagement, which is arranged between the Z-axis guide rails 34b and extends substantially parallel to them. The Z-axis ball screw 38b has one end coupled to a Z-axis stepper motor 40b to rotate the Z-axis ball screw 38b about its vertical central axis.When the Z-axis stepper motor 40b is powered, it rotates the Z-axis ball screw 38b around its vertical central axis, causing the nut to move the movable Z-axis plate 36b along the Z-axis guide rails 34b in one of the Z-axis directions.

[0027] The cutting unit 20a is attached to a lower section of the movable Z-axis plate 36a, whereas the cutting unit 20b is attached to a lower section of the movable Z-axis plate 36b. An image acquisition unit 42 for capturing images of an object, such as a workpiece 11 held on the clamping table 10, is located next to the cutting units 20a and 20b. The image acquisition unit 42 includes an image acquisition device, such as a CCD image sensor (charge-coupled device image sensor) or a CMOS image sensor (complementary metal oxide semiconductor image sensor), and an optical system with an optical device, such as a lens. The image acquisition unit 42 can be of any type, selected depending on the material or other properties of the workpiece 11.For example, the image acquisition unit 42 can have a visible light camera or an infrared camera as its image acquisition device. An image captured by the image acquisition unit 42 is used in a positioning operation of the workpiece 11 with respect to the cutting units 20a and 20b.

[0028] The base 4 further comprises a defined circular opening 4c along the opening 4b and in the upper surface of the base 4, opening upwards. The opening 4c accommodates a cleaning unit 44 for cleaning a workpiece 11. The cleaning unit 44 includes a centrifugal table 46 for holding and rotating the workpiece 11 and a nozzle 48 for supplying the workpiece 11, held by the centrifugal table 46, with cleaning fluid. The centrifugal table 46 has an upper surface that is essentially flat and parallel to the horizontal plane, i.e., the XY plane. The upper surface of the centrifugal table 46 serves as a holding surface 46a for holding the workpiece 11. The holding surface 46a is in fluid communication with a suction source (not illustrated), such as an ejector, via a suction channel (not illustrated) defined in the centrifugal table 46 and a valve (not illustrated).The centrifugal table 46 is coupled to a rotary actuator (not illustrated), such as an electric motor, for rotating the centrifugal table 46 about its vertical central axis, which is essentially parallel to the Z-axis. The nozzle 48 is arranged above the centrifugal table 46. The cleaning fluid supplied by the nozzle 48 is, for example, a liquid, such as pure water, or a mixture of liquid, such as pure water, and a gas, such as air. While the workpiece 11 is held against the centrifugal table 46, the rotary actuator rotates the centrifugal table 46 about its vertical axis, and the nozzle 48 supplies the cleaning fluid to the workpiece 11 to clean it.

[0029] A feeding mechanism (not illustrated) is arranged near openings 4b and 4c at base 4 for feeding a workpiece 11 between the clamping table 10 and the centrifugal table 46. After a workpiece 11 has been processed, i.e., cut, by the cutting units 20a and 20b, the workpiece 11 is conveyed by the feeding mechanism from the clamping table 10 to the centrifugal table 46, where it is cleaned. The cleaned workpiece 11 is then conveyed by the feeding mechanism from the cleaning unit 44 to the cassette 8, where it is stored.

[0030] A cover 50, which covers the components mounted on base 4, is arranged on base 4. In Fig. 1 The cover 50 has its contour indicated by double dot and dash lines.

[0031] The cutting device 2 also includes a display unit, that is, a display panel or display device 52, which is mounted on a side wall of the cover 50 for displaying various information relating to the cutting device 2. In particular, the display unit 52, which can have any number of different displays, shows various information relating to the processing of a workpiece 11, that is, processing conditions, processing details, etc. For example, the display unit 52 is a touch panel display. The display unit 52 in the form of a touch panel display also serves as an input unit, that is, as an input panel or input device for entering information into the cutting device 2, so that the operator can enter information into the cutting device by touching the display unit 52. In other words, the display unit 52 serves as a user interface.

[0032] A signaling unit, that is, a signal transmitter or signaling device, 54 for providing information to the operator is mounted on an upper wall of the cover 50. The signaling unit 54, which can be, for example, an indicator lamp, that is, a warning lamp, is switched on or flashes to indicate a fault to the operator in the event of a malfunction of the cutting device 2. However, the signaling unit 54 is not limited to a specific type. The signaling unit 54 can alternatively be a loudspeaker for transmitting information to the operator by means of a sound or speech.

[0033] The cutting device 2 further includes a control unit, that is, a control device 56, for controlling the cutting device 2. The control unit 56 is electrically connected to the components of the cutting device 2, that is, the cassette support table 6, the clamping table 10, the movement mechanism 12, the clamps 18, the cutting units 20a and 20b, the movement mechanisms 24a and 24b, the image acquisition unit 42, the cleaning unit 44, the display unit 52, the signal unit 54, etc. The control unit 56 outputs control signals to the components of the cutting device 2 in order to control the operations of the components and to operate the cutting device 2.The controller 56, for example, is a computer and includes a processor, such as a Central Processing Unit (CPU), for performing arithmetic operations and processing operations required to operate the cutting device 2, and a memory, such as a Read Only Memory (ROM) and a Random Access Memory (RAM), for storing various information, i.e., data, programs, etc., to be used for the operation of the cutting device 2.

[0034] A pair of ring-shaped cutting blades 58 for cutting a workpiece 11 are mounted on the cutting units 20a and 20b, respectively, such that the cutting blades 58 on the cutting units 20a and 20b face each other. Each of the cutting units 20a and 20b cuts a workpiece 11 held under suction on the clamping table 10 by causing the cutting blade 58 to cut into the workpiece 11 while rotating the cutting blade 58 about its central axis. The cutting device 2 can have one set of cutting units.

[0035] Fig. Figure 2A illustrates one of the cutting blades 58 in a top view. The cutting blade 58, which has a ring-shaped form, is made of a metallic material, such as a hard metal alloy or stainless steel, and does not contain, for example, abrasive grains. The cutting blade 58 can be a metal saw or a carbide cutting device. If the cutting blade 58 is a metal saw made of a carbide alloy, the carbide alloy can contain suitably selected metallic materials. The cutting blade 58 can, for example, be made of a composite material, that is, an alloy obtained by sintering a mixture of a carbide of a metal, such as tungsten, chromium, molybdenum, titanium, zirconium, hafnium, vanadium, niobium, or tantalum, and an iron metal, such as iron, cobalt, or nickel.In particular, a WC-CO alloy containing tungsten carbide (WC) and cobalt (Co) is suitable as a material for the cutting blade 58, as it exhibits high hardness over a wide temperature range and excellent mechanical strength. However, there are no restrictions regarding the material of the cutting blade 58. The cutting blade 58 could alternatively be, for example, a ring-shaped grinding wheel produced by bonding abrasive grains made of diamond, cubic boron nitride (CBN), or similar materials with a binder of metal, ceramic, resin, or similar material.

[0036] The cutting blade 58 has a circular opening 58a, defined centrally within it and extending through the cutting blade 58 in the thickness direction. The cutting blade 58 also has several sawtooth projections, i.e., teeth or serrations, 60 on its outer circumferential edge, which project radially outwards. The projections 60 are essentially identical in shape to one another and are arranged at essentially equal intervals along the outer circumferential edge of the cutting blade 58.

[0037] Fig. Figure 2B illustrates an enlarged, front partial view of an outer circumferential section of the cutting blade 58. As in Fig. As illustrated in Figure 2B, each of the projections 60 comprises a first surface, i.e., a rake surface 60a, and a second surface, i.e., a clearance surface 60b, which are essentially parallel to the thickness directions of the cutting edge 58. The first surface 60a and the second surface 60b are spaced apart from each other along the circumferential directions of the cutting edge 58 and each has radial outer ends, i.e., head ends, which are connected to each other and together form a head end 60c of the projection 60. The first surface 60a and the second surface 60b each have radial inner ends, i.e., base ends, which provide bases, i.e., cutting edge bases, 60d of the projection 60, which are connected to bases 60d of other adjacent projections 60.The angle of inclination at which the first surface 60a is inclined with respect to a radial direction of the cutting edge 58 is smaller than the angle of inclination at which the second surface 60b is inclined with respect to the radial direction of the cutting edge 58. In other words, the projection 60 is shaped such that the first surface 60a is steeper than the second surface 60b. For example, the first surface 60a extends parallel to the radial direction of the cutting edge 58, meaning that its angle of inclination is 0°, whereas the second surface 60b is oblique to the radial direction of the cutting edge 58, meaning that its angle of inclination is greater than 0°. The distance from the head end of the first surface 60a to its base end is less than the distance from the head end of the second surface 60b to its base end. The area of ​​the first surface 60a is smaller than the area of ​​the second surface 60b.

[0038] One of the cutting blades 58 is mounted on the cutting unit 20a (see Fig. 1) and rotatable in the direction indicated by arrow A (see Fig. 2A). In other words, the cutting blade 58 is rotated about its central axis such that the first surface 60a of each of the projections 60 is positioned in front of the second surface 60b in the direction indicated by arrow A. The cutting unit 20a cuts the workpiece 11 held on the clamping table 10 by causing the rotating cutting blade 58 to cut into the workpiece 11. The other cutting blade 58 is mounted on the cutting unit 20b in a similar manner (see Fig. 1) which cuts the workpiece 11 with the cutting blade 58. When the rotating cutting blade 58 cuts into the workpiece 11, mainly the first surfaces 60a of the projections 60 come into contact with the workpiece 11, scraping chips or shavings from the workpiece 11. The chips or shavings produced from the workpiece 11 when the cutting blades 58 cut the workpiece 11 are forced by the first surfaces 60a to move forward in the direction indicated by arrow A.

[0039] Structural details of cutting units 20a and 20b are described below using an example. Since cutting units 20a and 20b are identical, structural details of cutting unit 20a are described below.

[0040] Fig. Figure 3 illustrates the cutting unit 20a in an enlarged, perspective exploded view. As in Fig. As illustrated in Figure 3, the cutting unit 20a includes a column-shaped housing 62 which is coupled to the movement mechanism 24a (see Fig. 1) A cylindrical spindle 64, extending along the Y-axis, is rotatably mounted in the housing 62. The spindle 64 has an end section, i.e., a distal end section, which is exposed by the housing 62, and another end section, i.e., a proximal end section, which is connected to a rotary actuator (not illustrated), such as an electric motor. The distal end section of the spindle 64 has an opening 64a, which is defined therein in the axial direction by an inner circumferential wall surface 64b that is internally threaded.

[0041] A blade holder 66 is fixedly mounted to the distal end section of the spindle 64. The blade holder 66 includes a disc-shaped flange 68 and a cylindrical projection, i.e., a support shaft 70, which projects axially from a surface 68a of the flange 68. The blade holder 66 has an opening 66a, defined within it, which extends axially through the flange 68 and the projection 70. A fastening bolt 72 is inserted into the blade holder 66 through the opening 66a and into the opening 64a in the spindle 64, engaging the threaded inner circumferential wall surface 64b, thereby securing the blade holder 66 to the distal end section of the spindle 64.

[0042] An annular edge 68b projects axially from the surface 68a of the flange 68 along an outer circumferential edge thereof. The edge 68b has a flat distal end surface that is substantially parallel to the surface 68a and serves as a support surface for the cutting blade 58. The projection 70 has an outer circumferential wall surface 70a provided with an external thread.

[0043] The cutting blade 58 and an annular flange, i.e., a retaining flange 74 made of metal or a similar material, are mounted on the blade holder 66. The flange 74 has a circular opening 74a defined centrally within it, extending through the flange 74 in the thickness direction. When the projection 70 of the blade holder 66 is successively inserted through the opening 58a in the cutting blade 58 and the opening 74a in the flange 74, the cutting blade 58 and the flange 74 are supported on the blade holder 66. Then, an annular mounting nut 76 is engaged with the externally threaded outer circumferential wall surface 70a of the projection 70 and tightened, thus securing the cutting blade 58 and the flange 74 to the blade holder 66. As a result, the cutting blade 58 is gripped between the flange 68 and the flange 74 and firmly mounted on the distal end section of the spindle 64.

[0044] A blade cover 78 for covering the cutting blade 58, which is mounted on the distal end section of the spindle 64, i.e., the blade holder 66, is mounted on the housing 62. The blade cover 78 includes a main body 80, which is attached to a distal end section of the housing 62, and a sliding cover 82, which is slidable along the X-axis towards and away from the main body 80. The sliding cover 82 is operatively coupled to the main body 80 by a pneumatic cylinder 84. When air is supplied to a connector 86 on the main body 80, which is connected to the pneumatic cylinder 84, the air actuates the pneumatic cylinder 84 to cause the sliding cover 82 to move away from the main body 80 along the X-axis. The blade cover 78 is now open, allowing the cutting blade 58 to be mounted on the distal end section of the spindle 64.After the cutting blade 58 has been mounted on the spindle 64, the sliding cover 82 is caused to move along the X-axis towards the main body 80, which moves the blade cover 78 into a covering relationship with the cutting blade 58.

[0045] A connector 88 for supplying a fluid, such as pure water, i.e., a cutting fluid, is arranged on the main body 80. The main body 80 has a cutting fluid supply channel (not illustrated), which is defined therein and is connected to the connector 88. The cutting fluid supply channel has a distal end that opens toward the outer circumferential edge of the cutting blade 58. When the cutting fluid is supplied to the connector 88, the cutting fluid flows through the connector 88 into the cutting fluid supply channel, from which the cutting fluid is directed to the outer circumferential section of the cutting blade 58.

[0046] The sliding cover 82 has a pair of connectors 90 for supplying a fluid, such as pure water, and a pair of nozzles 92 connected to the connectors 90. The nozzles 92 are arranged relative to a lower section of the cutting blade 58, which is mounted on the distal end section of the spindle 64. The nozzles 92 have cutting fluid supply openings (not illustrated) defined in their respective distal end sections, opening towards the cutting blade 58. When the cutting fluid is supplied to the connectors 90, it flows through the connectors 90 into the nozzles 92 and is expelled from the cutting fluid supply openings towards the front and back of the cutting blade 58.

[0047] The cutting blade 58, mounted on the distal end section of the spindle 64, is rotated about its central axis, which is essentially parallel to the Y-axis, by rotational power generated by the rotary actuator connected to the spindle 64 and transmitted via the spindle 64 and the blade holder 66. The rotating cutting blade 58 cuts into the workpiece 11 (see Fig. 1) which cuts the workpiece 11. While the cutting blade 58 cuts the workpiece 11, the workpiece 11 and the cutting blade 58 are supplied with cutting fluid by the connectors 88 and 90. The cutting fluid supplied to the workpiece 11 and the cutting blade 58 cools the workpiece 11 and the cutting blade 58 and washes away chips produced from the workpiece 11 as it is cut by the cutting blade 58.

[0048] The blade cover 78 includes an image acquisition unit 94 for capturing images of the cutting blade 58. The image acquisition unit 94 captures images of the outer circumferential section of the cutting blade 58, which is mounted on the cutting unit 20a, making it possible to monitor the condition of the outer circumferential section of the cutting blade 58 in accordance with the captured images.

[0049] Fig. Figure 4 illustrates the image acquisition unit 94 in a partial sectional view from the front. As in Fig. As illustrated in Figure 4, the image acquisition unit 94 includes a light emitter 100 for emitting light and a light detector 110 for detecting light emitted by the light emitter 100. The light emitter 100 and the light detector 110 are arranged on each side of an upper end section of the cutting blade 58, which is mounted on the distal end section of the spindle 64, and are spaced apart from each other along the Y-axis across the upper end section of the cutting blade 58.

[0050] The light emitter 100 comprises a housing 102 in the form of a hollow rectangular cuboid. The housing 102 contains a light source 104, such as an LED, a condenser lens 106, and a mirror 108. Light emitted by the light source is directed onto the condenser lens 106, which is located below the light source 104. The light passing through the condenser lens 106 is focused and reflected by a surface of the mirror 108, which is located below the condenser lens 106, towards the light detector 110. The light reflected by the mirror 108, that is, the light emitted by the light emitter 100, travels in a direction essentially parallel to the Y-axis to reach the light detector 110.

[0051] The light detector 110 includes a microscope 112 for magnifying an image produced by the light emitted by the light emitter 100 and directed onto the light detector 110, and a camera 122 for recording the image magnified by the microscope 112. The microscope 112 comprises a housing 114 in the form of a hollow rectangular prism. The housing 114 contains a mirror 116 and a pair of convex lenses 118 and 120. The light from the light emitter 100 is directed into the light detector 110 by being reflected through a surface of the mirror 116 and then passes successively through the convex lenses 118 and 120. The light that passes through the convex lens 120 is directed onto the camera 122. The camera 122 includes an image acquisition device, such as a CCD image sensor or a CMOS image sensor, for converting the light from the microscope 112 into an electrical signal.The image capture device records an image that is reproduced by the electrical signal which has been converted from light.

[0052] The blade cover 78 has a defined gas supply channel 124. The gas supply channel 124 has a lower end that opens towards the upper end section of the cutting blade 58 and an upper end that is connected to a gas supply source 126. Gas, such as air, supplied from the gas supply source 126 to the gas supply channel 124 is expelled from the gas supply channel 124 towards the upper end section of the cutting blade 58, thereby removing foreign matter, such as chips and cutting fluid, that accumulates on the cutting blade 58.

[0053] With the cutting blade 58 mounted on the distal end section of the spindle 64, light travels from the light emitter 100 towards the light detector 110 when the light source 104 is energized to emit light. At this point, some of the light from the light emitter 100 is blocked by the outer circumferential section, i.e., the upper end section, of the cutting blade 58 and does not reach the light detector 110. When the camera 122 captures the light that has reached the light detector 110 and passed through the microscope 112, the image acquisition unit 94 takes a magnified image of the outer circumferential section of the cutting blade 58. For example, the image acquisition unit 94 takes a magnified image of the outer circumferential section of the cutting blade 58 before or after the cutting blade 58 processes the workpiece 11, or while the cutting blade 58 is processing the workpiece 11.The magnified image captured by the image acquisition unit 94 is used to check the extent to which the cutting blade 58 has worn, whether chips or cracks are present in the outer circumferential section of the cutting blade 58, and whether other defects or flaws are present, thereby monitoring the condition of the cutting blade 58. Before the image acquisition unit 94 captures an image of the cutting blade 58, gas is expelled from the gas supply channel 124 to the cutting blade 58 to blow away any foreign matter deposited on the cutting blade 58, thus preventing such foreign matter from appearing in the image of the cutting blade 58 captured by the image acquisition unit 94.

[0054] Fig. Figure 5A illustrates the cutting unit 20a in side view, and Fig. Figure 5B illustrates the cutting unit 20b in a side view. The respective cutting blades 58 are mounted on the cutting units 20a and 20b, and the cutting units 20a and 20b are arranged such that the cutting blades 58 mounted on them face each other along the Y-axis (see Figure 5B). Fig. 1) Each image acquisition unit 94 is mounted on the cutting units 20a and 20b for taking respective images of the outer circumferential sections, i.e. the upper end sections, of the cutting blades 58.

[0055] When the cutting device 2 is in operation, the cutting blades 58, which are mounted on the cutting units 20a and 20b, and the spindles 64 of the cutting units 20a and 20b are rotated in opposite directions, as viewed from the mounting nuts 76. For example, the cutting blade 58 mounted on the cutting unit 20a is rotated as indicated by arrow A in Fig. 5A indicated, rotated clockwise, whereas the cutting blade 58 mounted on the cutting unit 20b, as indicated by arrow B in Fig. 5B is shown, rotated counterclockwise. As described above, the cutting blades 58 are mounted on the respective cutting units 20a and 20b such that the first surface 60a of each projection 60 is positioned in front of its second surface 60b in the direction of rotation of the cutting blade 58. As shown in the Fig. 5A and Fig. As illustrated in Figure 5B, the cutting blades 58 are therefore mounted on the cutting unit 20a and 20b in opposite orientations, meaning their projections 60 face in opposite directions. When the operator is to install the cutting blades 58 on the cutting unit 20a and 20b, the operator must visually recognize the orientation of the small projections 60 and mount the cutting blades 58 in predetermined orientations, taking into account the direction in which the clamping table 10 is fed to the cutting units 20a and 20b for machining in order to cut the workpiece 11. Given these requirements, it is likely that the operator will install the cutting blades 58 with incorrect orientations. Assuming that the cutting blades 58 are mounted as shown in the figures, the operator will be able to install the cutting blades 58 with incorrect orientations. Fig. 5A and Fig. As illustrated in Figure 5B, where cutting units 20a and 20b are to be mounted with different orientations, there is a risk that the operator will misunderstand the correct orientations of the cutting blades 58 and is more likely to mount the cutting blades 58 with incorrect orientations. If the cutting blades 58 mounted with the wrong orientation are used to continuously cut the workpiece 11, the workpiece 11 will not be cut as intended by the operator, potentially causing machining errors.

[0056] In accordance with the present embodiment, the image acquisition unit 94 captures images of the outer circumferential sections of the cutting blades 58 mounted on the cutting units 20a and 20b, and the orientations of the cutting blades 58 are determined in accordance with the images of the cutting blades 58 captured by the image acquisition unit 94. Consequently, it is prevented that the cutting blades 58 continue to cut the workpiece 11 while mounted with incorrect orientations.

[0057] The determination of the orientations of the cutting blades 58 is carried out by the control 56 (see Fig. 1) the cutting device 2 is checked. Fig. Figure 6 illustrates the control 56 in block form. Fig. Figure 6 illustrates, in addition to the function blocks of the control unit 56, some components of the cutting device 2, namely the cutting unit 20a, the display unit 52, the signal unit 54, and the image acquisition unit 94. A procedure for determining the orientation of the cutting blade 58, which is mounted on the cutting unit 20a, is described below. However, the same procedure is also applicable to determining the orientation of the cutting blade 58, which is mounted on the cutting unit 20b.

[0058] As in Fig. As illustrated in Figure 6, the control unit 56 includes a processing section 130 for executing processes required to actuate the cutting device 2, and a storage section 136 for storing information, such as data and programs, used in the processes executed by the processing section 130. The processing section 130 includes a determination section 132 for determining the orientations of the cutting blade 58 mounted on the cutting unit 20a and an operating control 134 for controlling the operation of the components of the cutting device 2 in accordance with the orientations determined by the determination section 132.

[0059] The determining section 132 is electrically connected to the camera 122 of the image acquisition unit 94. The determining section 132 includes an image acquisition section 132a for capturing an image of the outer circumferential section, i.e., the upper end section, of the cutting blade 58. The image acquisition unit 94 captures an image of the outer circumferential section of the cutting blade 58, which is mounted on the cutting unit 20a. The image of the outer circumferential section of the cutting blade 58 captured by the image acquisition unit 94 is input into the image acquisition section 132a. Fig. Figure 7A illustrates the captured image labeled 140. The captured image 140 contains an image that reproduces a projection 60 of the cutting blade 58. The captured image 140 has left and right directions corresponding to the X-axis directions and up and down directions corresponding to the Z-axis directions. When the captured image 140 has been entered into the image acquisition section 132a by the image acquisition unit 94, the image acquisition section 132a stores the captured image 140 in the memory section 136.

[0060] The image acquisition unit 94 can capture multiple images of the outer circumferential section of the cutting blade 58 while the cutting blade 58 is rotated about its central axis, so that the image acquisition section 132a can capture multiple captured images 140. For example, the image acquisition unit 94 captures a sequence of images of the outer circumferential section of the cutting blade 58 until the cutting blade 58 completes a rotation. The images captured by the image acquisition unit 94 are input as captured images 140 into the image acquisition section 132a, which then captures the input captured images 140. Fig. Figure 7B illustrates a combined image 142, which is generated by combining the multiple captured images 140. When the image acquisition unit 94 has captured multiple images 140, the image acquisition section 132a can combine the images 140 to generate the combined image 142, which represents the entire outer circumference section of the cutting blade 58. The combined image 142 includes individual images of the projections 60 of the cutting blade 58. The image acquisition section 132a then stores the combined image 142 in the storage section 136.

[0061] The determination section 132 also includes an image processing section 132b for performing an image processing sequence on the captured image 140 or the combined image 142. The image processing section 132b performs an image processing sequence on the captured image 140 or the combined image 142, which is stored in the memory section 136, to extract information from the captured image 140 or the combined image 142 that is required to determine the orientation of the cutting blade 58, which is mounted on the cutting unit 20a. Specific examples of the image processing sequence performed by the image processing section 132b are described below.

[0062] Determination section 132 further includes an alignment determination section 132c for determining the alignment of the cutting blade 58 in accordance with the result of the image processing sequence. With reference to information output by image processing section 132b, alignment determination section 132c determines whether the cutting blade 58 is in a properly mounted or improperly mounted state on the cutting unit 20a. The properly mounted state refers to a state in which the cutting blade 58 is mounted on the cutting unit 20a such that the first surface 60a of the projection 60 is positioned in front of the second surface 60b of the projection in the direction of rotation of the cutting blade 58 (see Fig. 5A and Fig. 5B). On the other hand, the improperly mounted condition refers to a condition in which the cutting blade 58 is mounted on the cutting unit 20a in such a way that the first surface 60a of the projection 60 is positioned behind the second surface 60b of the cutting blade 58 in the direction of rotation.

[0063] The alignment determination section 132c outputs a signal indicating that the cutting blade 58 is in the properly mounted state, i.e., a "properly mounted" signal, or a signal indicating that the cutting blade 58 is in the improperly mounted state, i.e., an "improperly mounted" signal, as a determination result to the operating control 134. In response to the determination result from the alignment determination section 132c, i.e., the determination section 132, the operating control 134 controls operations of the components of the cutting device 2.

[0064] In particular, when the alignment determination section 132c inputs the correctly mounted signal into the operating control 134, the operating control 134 outputs control signals to the components of the cutting device 2 to bring the cutting device 2 into the state in which the cutting blade 58 cuts the workpiece 11. The workpiece 11 is now being cut by the cutting blade 58, which has been correctly mounted on the cutting unit 20a. If the alignment determination section 132c inputs the incorrectly mounted signal into the operating control 134, the operating control 134 outputs control signals to the components of the cutting device 2 to temporarily prevent the cutting device 2 from cutting the workpiece 11.The operating controller 134 also sends control signals to the display unit 52 and the signal unit 54 to issue a warning to alert the operator that the cutting blade 58 is mounted in the wrong orientation. For example, the operating controller 134 controls the display unit 52 to show a message indicating that the cutting blade 58 is mounted with the wrong orientation and also controls the signal unit 54 to turn it on or make it flash.

[0065] A process for determining the orientation in which the cutting blade 58 is mounted on the cutting unit 20a, using the cutting device 2, is described below with reference to the Fig. 6, Fig. 7, Fig. 8 to Fig. 9 described. The following describes in detail, by way of an example, a process in which the determining section 132 determines the orientation of the cutting blade 58 in accordance with the dimensions of the first surface 60a and the second surface 60b (see Fig. 2B).

[0066] First, the image acquisition unit 94 performs an image acquisition process to capture an image of the outer circumferential section of the cutting blade 58, thereby capturing a captured image 140 (see Fig. 7A). For example, the image acquisition unit 94 captures several images of the outer circumferential section of the cutting blade 58 while the cutting blade 58 is rotated about its central axis, so that the image acquisition section 132a can capture several captured images 140. The captured images 140 are then input into the image acquisition section 132a. The image acquisition section 132a then combines the captured images 140 into a combined image 142 (see Fig. 7B), which contains the respective images of the projections 60 of the cutting blade 58. The combined image 142 is then stored in memory section 136.

[0067] Then the image processing section 132b performs a cutting edge position detection process to detect the position of a head end, i.e. a cutting edge, of the cutting blade 58. Fig. Figure 8A illustrates a section of the combined image 142 where the cutting edge position detection process is to be performed.

[0068] During the cutting edge position detection process, the image processing section 132b reads the combined image 142 from the memory section 136 and then performs a binarization operation on the combined image 142. The binarization operation is performed to make the contour of the cutting blade 58, as represented by the combined image 142, more clearly visible. However, the binarization operation can be omitted if the combined image 142 represents the cutting blade 58 with sufficiently sharp contrast.

[0069] Next, the image processing section 132b detects the pixel gradations of a column at the left end of the combined image 142, that is, pixels of the first column, one after the other, moving downwards along the x-axis, and determines whether each pixel is displayed as white or black. Then, the image processing section 132b records the coordinate of a point as the coordinate of a head-end position of the cutting blade 58 where the display of the pixels in the combined image 142 changes from white to black. The above detection and determination cycle is then repeated for the pixels of the second and subsequent columns. In this way, the image processing section 132b acquires a collection of coordinates representing the head-end positions of the cutting blade 58.

[0070] Then the image processing section 132b performs a capture area setting operation to set an area in which dimensions of the cutting blade 58 are to be captured in the combined image 142. Fig. Figure 8B illustrates a section of the combined image 142 where the capture area setting operation is to be performed.

[0071] For example, image processing section 132b gives a minimum value Z min and a maximum value Z max from the Z-coordinates by referring to the coordinates of the head end positions of the cutting blade 58, which were acquired during the cutting edge position detection process. Then the image processing section 132b provides a range of Z-coordinates from the minimum Z min to the maximum Z maxIn the combined image 142, the area to be used for capturing the dimensions of the cutting blade 58 is defined. The area of ​​capture covers the images of the projections 60. Furthermore, the image processing section 132b sets limit values ​​to be used in an extreme value determination process described below. For example, the image processing section 132b calculates an average value Z. ave of the minimum value Z min and the maximum value Z max and represents a predetermined value between the minimum value Z min and the average value Z ave as first limit Z th1 one and a predetermined value between the maximum value Z max and the average value Z ave as a second limit Z th2 a.

[0072] Then, the image processing section 132b performs an extreme value determination operation to specify a maximum value and a minimum value of the coordinates of the head end positions of the cutting blade 58. Fig. Figure 8C illustrates a section of the combined image 142 where the extremum determination process is to be carried out.

[0073] For example, the image processing section 132b reads the Z-coordinates of the head end positions of the cutting blade 58 sequentially to the right, that is, in a -X-axis direction. At this point, the image processing section 132b reads the Z-coordinates of the head end positions of the cutting blade 58 while switching between a mode for capturing a maximum value of the Z-coordinates, that is, a maximum value capture mode, and a mode for capturing a minimum value of the Z-coordinates, that is, a minimum value capture mode.

[0074] In particular, the image processing section 132b, in maximum value acquisition mode, reads the Z-coordinates of the head end positions of the cutting blade 58 sequentially in the x-axis direction. If the Z-coordinates of the head end positions of the cutting blade 58 are equal to or less than the first limit value Z th1 When the maximum value acquisition mode is switched to the minimum value acquisition mode, image processing section 132b determines a maximum value of the Z-coordinates that were read out in the maximum value acquisition mode. Then, image processing section 132b records the coordinate of a point as the coordinate of the head end 60c (see Fig. 2B) of the projections 60 of the cutting blade 58, where the maximum value, that is, a maximum point 142a, occurs. Next, the image processing section 132b reads the Z-coordinates of the head-end positions of the cutting blade 58 sequentially in the -X-axis direction during the minimum value acquisition mode. If the Z-coordinates of the head-end positions of the cutting blade 58 are equal to or greater than the second limit Z th2 When the minimum value acquisition mode is switched to the maximum value acquisition mode, image processing section 132b indicates a minimum Z-coordinate value that was read during the minimum value acquisition mode. Then, image processing section 132b plots the Z-coordinate of a point where the minimum value occurs, that is, a minimum point 142b, as the Z-coordinate of the grounds 60d (see Fig. 2B) of the projections 60 of the cutting blade 58. The image processing section 132b repeats the above process to determine the coordinates of several maximum points 142a and several minimum points 142b contained in the combined image 142.

[0075] Although the two limit values, that is, the first limit value Z th1 and the second limit Z th2 To define a time sequence in which a switch between the maximum value acquisition mode and the minimum value acquisition mode is to be performed during the acquisition range setting process and the extreme value determination process described above, a single limit value can be used to define such a time sequence. For example, a limit value Z ave (see Fig. 8B) can be used, which has an average value of the first limit Z th1 and the second limit Z th2reproduces. If the recorded images are 140 (see Fig. 7A) to be combined into the combined image 142, the image of the cutting blade 58 may, however, be interrupted at the transitions between the recorded images 140, resulting in small steps or discontinuities in the combined image 142 that are not actually present in the cutting blade 58. Assuming that the only limit Z ave is used and the Z-coordinate reaches the limit Z at such a step or discontinuity aveIf the levels or discontinuities overlap, the maximum value acquisition mode may incorrectly switch to the minimum value acquisition mode, or vice versa, so that the upper and lower ends of the level or discontinuity are incorrectly captured as a maximum point 142a and a minimum point 142b, respectively. If, on the other hand, the two limit values, that is, the first limit value Z th1 and the second limit Z th2 , are used and the difference between these is set so that the level or discontinuity does not correspond to both of the limit values ​​Z th1 and Z th2 Overlapping, on the other hand, prevents extreme values ​​from being falsely recorded at steps or discontinuities.

[0076] Next, image processing section 132b performs a dimension calculation operation to calculate the dimensions of the first surface 60a and the second surface 60b (see Fig. 2B) in accordance with the coordinates of the maximum point 142a and the minimum point 142b. For example, the image processing section 132b calculates a value corresponding to the distance between the head end 60c and the base 60d (see Fig. 2B) of the projection 60 corresponds to the cutting blade 58. Fig. Figure 9 illustrates a section of the combined image 142 where the dimension calculation process is to be performed.

[0077] First, image processing section 132b calculates a distance D1 along the X-axis between a predetermined maximum point 142a and a minimum point 142b, which is positioned to the right of the maximum point 142a. Next, image processing section 132b calculates a distance D2 along the X-axis between the minimum point 142b, which was used to calculate distance D1, and a maximum point 142a, which is positioned to the right of the minimum point 142b. Furthermore, image processing section 132b calculates a distance D1 along the X-axis between the maximum point 142a, which was used to calculate distance D2, and a minimum point 142b, which is positioned to the right of the maximum point 142a.Image processing section 132b repeats the above processing cycle with respect to all maximum points 142a and minimum points 142b, thereby calculating multiple distances D1 and multiple distances D2 in the combined image 142. Image processing section 132b then calculates an average value of the distances D1 and an average value of the distances D2 and outputs the calculated averages to the alignment determination section 132c. Alternatively, image processing section 132b can output a total value of the distances D1 and a total value of the distances D2 to the alignment determination section 132c.

[0078] The orientation determination section 132c performs an orientation determination operation to determine the orientation of the cutting blade 58, which is mounted on the cutting unit 20a, in accordance with the values ​​input by the image processing section 132b. For example, the orientation determination section 132c compares the average or total value of the distances D1 and the average or total value of the distances D2 and determines the orientation of the cutting blade 58 in accordance with the relationship of the heights of the compared values.

[0079] In particular, if the cutting blade 58 is mounted on the cutting unit 20a such that the first surface 60a of each projection 60 is positioned in the direction of rotation of the cutting blade 58 in front of its second surface 60b (see Fig. 5A), the image acquisition section 132a generates the in Fig. Figure 9 illustrated the combined figure 142. In the combined figure 142, the average value of the distances D1 from the maximum points 142a to the minimum points 142b is smaller than the average value of the distances D2 from the minimum points 142b to the maximum points 142a. In this case, the alignment determination section 132c determines that the cutting blade 58 is properly mounted on the cutting unit 20a, that is, in the properly mounted state, and outputs a properly mounted signal to the operating control 134.

[0080] If, on the other hand, the cutting blade 58 is incorrectly mounted on the cutting unit 20a, such that the first surface 60a of each projection 60 is positioned behind the second surface 60b in the direction of rotation of the cutting blade 58, the image acquisition section 132a produces a combined image that is a horizontal inversion of the one shown in Fig. This is illustrated in the combined image 142 shown in Figure 9. In the reverse of the combined image 142, the average value of the distances D1 from the maximum points 142a to the minimum points 142b is greater than the average value of the distances D2 from the minimum points 142b to the maximum points 142a. In this case, the alignment determination section 132c determines that the cutting blade 58 is not properly mounted on the cutting unit 20a, i.e., is in the improperly mounted state, and outputs an improperly mounted signal to the operating control 134.

[0081] For example, memory section 136 stores in advance reference information that represents the relationship between the dimensions of the projections 60 and a state of the cutting blade 58, that is, the properly mounted state or the improperly mounted state. In accordance with the dimensional values ​​input by the image processing section 132b and the reference information, the alignment determination section 132c determines whether the cutting blade 58 is in the properly mounted state or the improperly mounted state.

[0082] As described above, the image processing section 132b calculates values ​​that correspond to the dimensions of the projections 60 of the cutting blade 58, the image of which was acquired by the image acquisition unit 94. The alignment determination section 132c determines the alignment of the cutting blade 58 in accordance with dimensional values ​​calculated by the image processing section 132b. Values ​​calculated by the image processing section 132b are not limited to the average or total value of the distances D1 and the average or total value of the distances D2 and can be other values. For example, the image processing section 132b can calculate even distances from the maximum points 142a to the minimum points 142b and even distances from the minimum points 142b to the maximum points 142a and output the calculated even distances to the alignment determination section 132c.

[0083] The determination operations performed by the determination section 132 are carried out when programs stored in the memory section 135 are executed by the determination section 132. In particular, the memory section 136 stores programs that describe the operations to be performed by the image acquisition unit 94 and the determination section 132. The control unit 56 reads the programs from the memory section 136 and executes them to automatically determine the orientation of the cutting blade 58.

[0084] As described above, the cutting device 2, in accordance with the present embodiment, is able to determine the orientation of the cutting blade 58 mounted on the cutting unit 20a in accordance with the images captured by the image acquisition unit 94 from the projections 60 of the cutting blade 58. This prevents the workpiece from being continuously cut by the cutting blade 58, which is mounted on the cutting unit 20a in an incorrect orientation, thus preventing machining errors caused by the incorrectly oriented cutting blade 58.

[0085] In the above embodiment, the determining section 132 determines the orientation of the cutting blade 58 in accordance with the dimensions of the projections 60 of the cutting blade 58 by way of an example. However, the present invention is not limited to the above process for determining the orientation of the cutting blade 58. For example, the determining section 132 can determine the orientation of the cutting blade 58 in accordance with inclinations of the first surfaces 60a and the second surfaces 60b of the projections 60. Such another process for determining the orientation of the cutting blade 58 is described below with reference to the Fig. 6 and 10A to 10C described.

[0086] First, the image acquisition unit 94 successively captures several images of the outer circumference section of the cutting blade 58, thus recording multiple images in accordance with the process described above. The image acquisition section 132a combines the captured images to produce a combined image and stores the combined image in the memory section 136. Fig. Figure 10A illustrates the combined image labeled 152, which is produced by combining the captured, multiple images labeled 150. Fig. Figure 10A shows the combined image 152, the projections 60 of the cutting blade 58, each projection 60 having a first surface 60a and a second surface 60b which are essentially straight when viewed from the front.

[0087] Next, the image processing section 132b reads the combined image 152 from the memory section 136 and performs a binarization operation on the combined image 152. The binarization operation can be omitted if the combined image 152 reproduces the cutting blade 58 with sufficiently sharp contrast.

[0088] Then, the image processing section 132b performs an image processing operation to detect edges in the combined image 152, that is, an edge detection operation to detect head ends, i.e., cutting edges of the cutting blade 58. When the image processing section 132b performs the edge detection operation on the combined image 152, it generates an edge detection image in which points where the display of pixels of the combined image 152 changes from white to black are displayed in white, and other areas of the combined image 152, as shown in Fig. 10B illustrates this, and will be displayed in black. Fig. Figure 10B illustrates the edge detection image, which is labelled by 154. The edge detection image 154 includes an edge line 154a, which represents the edges contained in the combined image 152. The edge line 154a traces the shape of the head ends of the cutting blade 58.

[0089] The image processing section 132b then performs an image processing operation on the edge detection image 154, that is, a straight line extraction operation to extract straight line components belonging to the edge line 154a. Fig. Figure 10C illustrates the edge detection image 154, on which the extraction process of straight lines is to be performed.

[0090] As in Fig. As illustrated in Figure 10C, the straight line 154a contains several components of first straight lines 156a, which correspond to the first surfaces 60a (see Fig. 2B) correspond to the cutting blade 58, and several components of second straight lines 156b, which correspond to the second surfaces 60b (see Fig. 2B) of the cutting blade 58 correspond. The angle of inclination of the first straight lines 156a with respect to the Z-axis is smaller than the angle of inclination of the second straight lines 156b with respect to the Z-axis. In other words, the first straight lines 156a and the second straight lines 156b can be distinguished from each other according to their angles of inclination.

[0091] Image processing section 132b performs the straight line extraction operation on the edge detection image 154 to extract several straight lines belonging to edge line 154a. Image processing section 132b then specifies the angles of the extracted straight lines and classifies them according to their inclination angles into first straight lines 156a and second straight lines 156b. For example, image processing section 132b performs a Hough transform on the edge detection image 154 to extract several straight lines belonging to edge line 154a and specify the inclination angles of the straight lines. Furthermore, image processing section 132b compares the inclination angles of the extracted straight lines with a preset threshold to classify the straight lines as first straight lines 156a and second straight lines 156b.Then the image processing section 132b outputs an average value of the inclination angles of the first straight lines 156a and an average value of the inclination angles of the second straight lines 156b to the alignment determination section 132c.

[0092] The orientation determination section 132c performs an orientation determination process to determine the orientation of the cutting blade 58, which is mounted on the cutting unit 20a, in accordance with the values ​​(angles of the first straight line 156a and the second straight line 156b) input by the image processing section 132b. For example, the orientation determination section 132c determines the orientation of the cutting blade 58 in accordance with the direction in which the second straight line 156b is inclined with respect to the first straight line 156a.

[0093] In particular, when the cutting blade 58 is mounted on the cutting unit 20a such that the first surface 60a of each projection 60 is positioned in the direction of rotation of the cutting blade 58 in front of the second surface 60b (see Fig. 5A), the image acquisition section 132a generates the edge acquisition image 154, which is in Fig. Figure 10C illustrates this. In the edge detection image 154, the second straight line 156b is inclined at a predetermined clockwise angle relative to the first straight line 156a. In this case, the alignment determination section 132c determines that the cutting blade 58 is properly mounted on the cutting unit 20a, i.e., in the properly mounted state, and outputs a properly mounted signal to the operating control 134.

[0094] If, on the other hand, the cutting blade 58 is incorrectly mounted on the cutting unit 20a, such that the first surface 60a of each projection 60 is positioned behind the second surface 60b in the direction of rotation of the cutting blade 58, the image acquisition section 132a generates an edge acquisition image that is a horizontal inversion of the Fig. The edge detection image 154 is illustrated in Figure 10C. In the reverse of edge detection image 154, the second straight line 156b is inclined counterclockwise at a predetermined angle with respect to the first straight line 156a. In this case, the alignment determination section 132c determines that the cutting blade 58 is not properly attached to the cutting unit 20a, i.e., it is in the improperly mounted state, and outputs an improperly mounted signal to the operating control 134.

[0095] As described above, the image processing section 132b can extract the first straight line 156a and the second straight line 156b that correspond to the first surface 60a and the second surface 60b, respectively, of the projection 60 of the cutting blade 58. In this case, the orientation determination section 132c determines the orientation of the cutting blade 58 in accordance with the relationship between the inclinations of the first straight line 156a and the second straight line 156b extracted by the image processing section 132b.

[0096] The determination section 132 can alternatively determine the orientation of the cutting blade 58 in accordance with the result of a comparison between the image of each projection 60 of the cutting blade 58 and a reference image. In other words, the determination section 132 can determine the orientation of the cutting blade 58 according to pattern recognition. Such an alternative determination process for the orientation of the cutting blade 58 is described below with reference to the Fig. 6 and 11A to 11C described.

[0097] First, the memory section 136 of the controller 56 stores a reference image that has been captured in advance. The reference image is an image of a projection 60 that is captured when the image acquisition unit 94 captures an image of the outer circumferential section of the cutting blade 58 when the cutting blade 58 is in the properly assembled state. Fig. Figure 11A illustrates the reference image marked by 160.

[0098] To determine the orientation in which the cutting blade 58 is mounted on the cutting unit 20a and 20b respectively, the image acquisition unit 94 takes an image of the outer circumferential section of the cutting blade 58, and the image acquisition section 132a captures the captured image. In this way, the image of a projection 60 of the cutting blade 58, which is mounted on the cutting unit 20a or 20b, is captured. Fig. 11B illustrates the recorded image of the projection 60 of the cutting blade 58, as indicated by 162a, in the properly assembled state, whereas Fig.Figure 11C illustrates the captured image of the projection 60 of the cutting blade 58, labeled 162b, in its improperly mounted state. When the image acquisition unit 94 captures an image of the outer circumferential section of the cutting blade 58, it captures either the captured image 162a or the captured image 162b, depending on how the cutting blade 58 is mounted on the cutting unit 20a or 20b, respectively. The image acquisition section 132a then stores the captured image 162a or the captured image 162b in the storage section 136.

[0099] Next, the image processing section 132b reads the reference image 160 and the captured image 162a or 162b, which have been stored in the memory section 136, and calculates a degree of similarity between the reference image 160 and the captured image 162a or 162b. If the cutting blade 58 is properly mounted on the cutting units 20a and 20b, respectively, the captured image 162a is captured and compared with the reference image 160. As a result, the image processing section 132b calculates a high degree of similarity between the captured image 162a and the reference image 160. Conversely, if the cutting blade 58 is not properly mounted on the cutting units 20a and 20b, respectively, the captured image 162b is captured and compared with the reference image 160.As a result, the image processing section 132b calculates a low degree of similarity between the captured image 162b and the reference image 160. The image processing section 132b then outputs a signal to the alignment determination section 132c, which represents the result of the comparison, that is, the degree of similarity between the reference image 160 and the captured image 162a or the captured image 162b.

[0100] The orientation determination section 132c specifies, in accordance with the result of the comparison between the reference image 160 and the captured image 162a or 162b, the orientation in which the cutting blade 58 is mounted on the cutting units 20a and 20b, respectively. For example, the memory section 136 stores a limit value for the degree of similarity in advance, and the orientation determination section 132c compares the degree of similarity input by the image processing section 132b with the limit value read from the memory section 136. If the degree of similarity calculated by the image processing section 132b is equal to or greater than the limit value, the orientation determination section 132c determines that the cutting blade 58 is correctly mounted on the cutting units 20a and 20b, respectively.On the other hand, if the degree of similarity calculated by the image processing section 132b is lower than the limit value, the alignment determination section 132c determines that the cutting blade 58 is not properly mounted on the cutting units 20a and 20b, respectively.

[0101] As described above, the image processing section 132b can compare the image of the projection 60 of the cutting blade 58, which was captured by the image acquisition unit 94, with the reference image. The alignment determination section 132c determines the alignment of the cutting blade 58 in accordance with the comparison result between the image of the projection 60 and the reference image.

[0102] The structure, method, etc., in accordance with the above embodiment and variations, can be appropriately altered or modified without leaving the scope of protection of the present invention.

Claims

[1] Cutting device (2) for cutting a workpiece (11) comprising: a clamping table (10) with a holding surface (10a) for holding the workpiece (11) on it; a cutting unit (20a, 20b) comprising a spindle (64) with a cutting blade (58) mounted at its distal end for cutting the workpiece (11) held on the holding surface (10a); an image acquisition unit (94) for capturing an image of an outer circumferential section of the cutting blade (58) mounted on the cutting unit (20a, 20b); and a determination section (132) for determining an orientation of the cutting blade (58), wherein the outer circumferential section of the cutting blade (58) has several projections (60) each having a first surface (60a) for scraping chips from the workpiece (11) when the cutting blade (58) cuts the workpiece (11), and a second surface (60b) connected to the first surface (60a), and wherein the determining section (132) determines the orientation of the cutting blade (58) mounted on the cutting unit (20a, 20b) in accordance with an image taken by the image acquisition unit (94) of the projections (60). [2] Cutting device (2) according to claim 1, wherein the determining section (132) determines the orientation of the cutting blade (58) in accordance with the dimensions of the first surface (60a) and the second surface (60b) of the projections (60) in their image, which has been recorded by the image acquisition unit (94). [3] Cutting device (2) according to claim 1, wherein the determining section (132) determines the orientation of the cutting blade (58) in accordance with inclinations of the first surface (60a) and the second surface (60b) of the projections (60) in their image, which has been recorded by the image acquisition unit (94). [4] Cutting device (2) according to claim 1, wherein the determining section (132) determines the orientation of the cutting blade (58) in accordance with a comparison result between the image taken by the projections (60) through the image acquisition unit (94) and a reference image.

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