WO2018058238A1

WO2018058238A1 - Detection apparatus and method for saw blade sharpening operations

Info

Publication number: WO2018058238A1
Application number: PCT/CA2017/051129
Authority: WO
Inventors: Justin Williams; Glen Springle
Original assignee: Williams & White Machine Inc.
Priority date: 2016-09-27
Filing date: 2017-09-25
Publication date: 2018-04-05
Also published as: CA3031699A1; US20210016416A1; DE112017004825T5

Abstract

An apparatus for positioning a feed finger of a saw sharpening machine with a saw blade mounted in the saw sharpening machine includes a tooth detection unit which is used to detect the position of a tooth of the saw blade relative to the feed finger. The tooth detection unit comprises an object detection sensor that is mounted to the feed finger facing the tooth and is used to determine the position of the tooth and an adjacent gullet. Once the position of the tooth and gullet is determined, the feed finger is moved into the gullet and the feed finger is actuated to advance the saw blade into a position for a tooth grinding operation.

Description

DETECTION APPARATUS AND METHOD FOR SAW BLADE SHARPENING OPERATIONS

FIELD OF THE INVENTION

Illustrative embodiments of the present invention generally relate to detection apparatus and methods for a saw blade sharpening operation, such as detecting a position of a saw blade tooth of a saw blade in a saw sharpening machine.

BACKGROUND

Saw sharpening machines are used to sharpen saw teeth of saw blades.

For example, in an embodiment disclosed in the Applicant's prior PCT publication no. WO 2013/091 1 10, a type of Computer Numerical Control (CNC) saw sharpening machine known as a saw grinding apparatus is used to move a saw blade into a loading position and then into a sharpening position, to rotatably advance a tooth of the saw blade, to secure the saw blade in a tooth grinding position, to grind the tooth, and to continue to rotatably advance and grind each tooth of the blade. To rotatably advance each successive tooth of the saw blade for grinding, a feed finger subassembly 24 shown in Figure 8 of WO 2013/091 1 10 has a feed finger 102 which can move in a first degree of freedom by pivoting in the plane of the saw blade, and in a second degree of freedom by extending horizontally in the plane of the saw blade.

Similarly, other prior CNC saw sharpening machines have also conventionally employed a feed finger having no more than two degrees of freedom. A partial exception can be found in U.S. Patent No. 6,907,809, which provides a pneumatic cylinder and a biasing spring that allow a feed finger to be pivoted over only a very short range of small-radius arcuate motion to move the finger into and out of the plane of the saw blade, while larger ranges of motion parallel to the plane of the saw blade are permitted. To perform high quality sharpening on a saw tooth, it is desirable to precisely move each tooth of a saw blade requiring sharpening into a specific sharpening position. Precisely locating the feed finger relative to the saw blade is an aspect of precisely placing the saw tooth into the sharpening position.

SUMMARY

In accordance with aspects of the invention, there is provided a method and an apparatus for determining a position of a saw blade mounted in a saw sharpening machine that uses an object detection sensor. The method comprises: positioning an object detection sensor beside an outer edge of a saw blade such that the object detection sensor faces a row of alternating saw teeth and gullets on the outer edge of the saw blade; moving the object detection sensor relative to the row of alternating saw teeth and gullets until the object detection sensor is in an aligned position wherein the object detection sensor faces and detects a first tooth or a first gullet; and determining a position of the first tooth or the first gullet from the aligned position of the object detection sensor. The apparatus comprises the object detection sensor, one or more motors coupled to the object detection sensor such that actuation of the one or more motors moves the object detection sensor relative to the saw blade, and a processor. The processor has a memory encoded with program code executable by the processor to: operate the one or more motors to move the object detection sensor relative to the row of alternating saw teeth and gullets until the object detection sensor is in an aligned position wherein the object detection sensor faces and detects a first tooth or a first gullet; and determine a position of the first tooth or the first gullet from the aligned position of the object detection sensor.

The object detection sensor can be an optical sensor, inductive sensor, or a capacitive proximity sensor. The optical sensor can be a photoelectric sensor, fiber optic sensor, or a laser sensor. The optical sensor can be a reflective type and comprise an emitter and an adjacent detector that both face the saw blade, or an opposed type where the emitter and the detector are on opposite sides of the saw blade.

The object detection sensor can be affixed to a feed finger of the saw sharpening machine at a known location relative to a feed fingertip of the feed finger. The method can further comprise: moving the feed finger relative to the row of alternating saw teeth and gullets until the object detection sensor is in the aligned position, and determining the position of the feed fingertip relative to a target gullet, wherein the position of the target gullet and the first tooth or the first gullet is known.

The step of moving the feed finger can comprise: advancing the feed finger in a direction parallel to the saw blade such that the object detection sensor moves past an expected location of the first gullet and the first tooth; reading the object detection sensor and retracting the feed finger in a direction parallel to the saw blade until the object detection sensor does not detect a signal above a detection threshold; then, the stop retracting the feed finger and indicate that the object detection sensor is in the aligned position. The feed fingertip can be inserted into the target gullet when the object detection sensor is in the aligned position and the location of the feed fingertip relative to the target gullet is determined. The feed finger can then be advanced to move the saw blade, the feed fingertip can be withdrawn out of the target gullet, and the feed finger can be retracted into a home position.

The method can further comprise positioning a saw blade data reader such as a bar code scanner at a computer readable data source such as a bar code on the saw blade, and reading data stored on the bar code. The data stored on the bar code can include information about the saw blade, in which case the method further comprises decoding the data and executing a computer aided manufacturing program to perform a saw sharpening operation on the saw blade using the decoded information. Other aspects and features of illustrative embodiments of the present invention will become apparent to those ordinarily skilled in the art upon review of the following description of such embodiments in conjunction with the accompanying figures.

BRIEF DESCRIPTION OF THE DRAWINGS

In drawings which illustrate embodiments of the invention,

Figure 1 is an isometric view of a feed finger positioning apparatus having a tooth detection unit according to an illustrative embodiment of the invention, shown with several protective outer skirts removed for ease of illustration;

Figure 2 is a back view of the feed finger positioning apparatus of Figure 1 ;

Figure 3 is a top view of an X-motion unit of the feed finger positioning apparatus of Figure 1 with some components removed for ease of illustration;

Figure 4 is a back-left view of a Z-motion unit of the feed finger positioning apparatus of Figure 1 with some components removed for ease of illustration;

Figure 5 is a right-front view of a Y-motion unit of the feed finger positioning apparatus of Figure 1 with some components removed for ease of illustration;

Figure 6 is a top view of a feed finger of the apparatus of Figure 1 in a side- switch cycling mode;

Figure 7 is a rear right view of a feed finger of the apparatus of Figure 1 in an over-the-top cycling mode; Figure 8 is a front view of the feed finger positioning apparatus of Figure 1 ;

Figure 9 is a top view of the feed finger positioning apparatus of Figure 1 ;

Figure 10 is a bottom view of the feed finger positioning apparatus of Figure

1 ; Figure 11 is a left view of the feed finger positioning apparatus of Figure 1 ;

Figure 12 is a right view of the feed finger positioning apparatus of Figure 1 ;

Figures 13A to 13D provide exploded views of components of the feed finger positioning apparatus of Figure 1 ;

Figure 14 a flow chart illustrating an operation for detecting the position of a saw tooth using the tooth detection unit;

Figure 15 is a flow chart illustrating a saw tooth indexing operation performed by the feed finger positioning apparatus.

DETAILED DESCRIPTION Directional terms such as "up", "down", "above" and "below" are used in this description merely to aid in describing the embodiments of the invention and are not to be construed as limiting the embodiments to any particular orientation during operation or in connection to the environment or another object. Additionally, the term "couple" and variants of it such as "coupled", "couples", and "coupling" as used in this description are intended to include indirect and direct connections unless otherwise indicated. For example, if a first element is coupled to a second element, that coupling may be through a direct connection or through an indirect connection via other elements and connections. According to some embodiments of the invention described herein, a tooth detection unit is part of a saw sharpening machine comprising a feed finger assembly, and is used to detect the position of a tooth of a saw blade mounted in the saw sharpening machine relative to the feed finger assembly. The tooth detection unit comprises an object detection sensor that is mounted to the feed finger assembly facing the saw blade and is used to determine the position of the tooth and/or an adjacent gullet of the saw blade. The tooth detection sensor can be an optical sensor, or another type of object detection sensor as is known in the art. Once the position of the tooth and/or gullet is determined, a feed finger of the feed finger assembly is moved into the gullet and the feed finger assembly is actuated to advance the saw blade into a position for a tooth sharpening operation.

According to some other embodiments of the invention, the saw sharpening machine can additionally or alternatively include a bar code reading unit that comprises an optical sensor that reads a bar code on a saw blade mounted in the saw sharpening machine. The bar code can include information about the type of teeth on the saw blade; this information can be used by the saw sharpening machine to automatically determine the type of saw sharpening operation to be performed on the teeth of the saw blade. Saw sharpening machine

The tooth detection unit can be incorporated into known saw sharpening machines, such as those that perform grinding operations on the teeth of a saw blade. More particularly, the tooth detection unit can be part of a CNC saw sharpening machine having a feed finger assembly that advances a tooth of a circular saw blade mounted in the saw sharpening machine into a grinding position. One specific example of a suitable saw sharpening machine for use with the tooth detection unit is a CNC saw grinding apparatus disclosed in Applicant's above-noted PCT publication no. WO 2013/091 1 10, which is herein incorporated by reference. This saw sharpening machine can be adapted to include a feed finger assembly comprising the tooth detection unit as shown in Figures 1 to 13, and described below.

Alternatively, the tooth detection until can be incorporated into other types of saw sharpening machines, such as an machines that use electrical discharge machining (EDM) to sharpen diamond tipped saw blades.

Feed Finger Assembly and Tooth Detection Unit Overview

Referring to Figures 1 , 7 and 13D, and according to a first embodiment of the invention, a feed finger assembly is shown generally at 100 and a tooth detection unit is shown generally at 200. In this embodiment, the tooth detection unit 200 is configured to determine the position of a tooth and adjacent gullet of a saw blade 120 mounted adjacent to the feed finger assembly 100, and the feed finger assembly 100 is configured to position a feed finger 110 to engage with the saw blade 120.

In the present embodiment, the tooth detection unit 200 comprise an optical- based object detection sensor mounted on the feed finger 110 such that light from an emitter 202 of the sensor is directed at the tooth of an adjacent saw blade 120 and light reflected from the tooth can be detected by a detector 204 of the sensor. The feed finger assembly 100 includes a first motion unit 300 configured to move the feed finger in a first degree of freedom, a second motion unit 400 configured to move the feed finger in a second degree of freedom different than the first degree of freedom, and a third motion unit 500 configured to move the feed finger in a third degree of freedom different than the first and second degrees of freedom. In this embodiment, the third degree of freedom includes linear translational motion in a direction having a nonzero component normal to a plane of the saw blade 120. More particularly, in this embodiment the direction is normal to the plane of the saw blade.

Alternatively, the tooth detection unit 200 can be used with different feed finger assemblies, such as the feed finger assembly disclosed in PCT publication WO 2013/091 1 10, and other known feed finger assemblies having only two degrees of freedom.

In this embodiment, the feed finger assembly 100 is a component of the multiple axis CNC grinding machine disclosed in PCT publication no. WO 2013/091 1 10. Consequently, in this embodiment the feed finger assembly

100 includes chain-link wire guides such as those shown at 160 in Figure 1 , through which both electrical power wires and computer control wires are routed, to protect the wires against chafing or other wear as the various components of the feed finger assembly 100 move as described below. Referring to Figures 1 , 2, 6 and 7, in this embodiment the feed finger 110 includes a feed finger shaft 112 and a feed fingertip 114, which in this embodiment includes a carbide tip. In this embodiment, the feed finger 110 is bolted to a lower surface of an upper plate 140 of the feed finger assembly 100. To strengthen the connection of the feed finger 110 to the upper plate 140, in this embodiment an arm gusset 170 shown in Figure 1 is bolted to the upper plate 140 adjacent the feed finger 110, and three dowels 172 connect the feed finger 110 to the arm gusset 170.

In this embodiment the feed fingertip 114 has an angular offset relative to a normal to the plane of the saw blade 120. More particularly, in this embodiment the shaft 112 lies in a plane parallel to that of the saw blade 120 such that a normal to a rear surface 118 of the shaft 112 is parallel with a normal to the saw blade, and the fingertip 114 extends from an angled surface 116 that extends frontward and upward from the rear surface 118 by an angle of 42 degrees. Thus, in this embodiment the angular offset of the feed fingertip relative to a normal to the saw blade plane is 42 degrees.

In this regard, such an angular offset is advantageous, particularly for certain types of saw blades. The teeth of some saw blades have shear face angles, and in some cases alternating teeth have opposite shear angles. In such cases, it is important to accurately position the feed fingertip 114 in the center of each tooth, to achieve an accurate and even grind. Therefore, in this embodiment the angular offset of the fingertip 114 exceeds the largest expected shear angle of typical saw blades, which ensures that the fingertip 114 can properly contact the center of each tooth, and thereby facilitates accurate automated side locating of the feed fingertip 114. Conversely, however, the angular offset is not excessively larger than the largest expected shear angle: in this regard, maintaining a smaller angular offset advantageously permits the feed fingertip 114 to laterally fit into and out of smaller gullets. X-Motion Unit of the Feed Finger Assembly

Referring to Figures 1 , 2 and 3, in this embodiment, the first motion unit 300 is configured to linearly translate the feed finger along a first axis. More particularly, in this embodiment the first axis is denoted as the X-axis and extends horizontally in a direction parallel to the plane of the saw blade.

In this embodiment, the first motion unit 300 moves the feed finger 110 in the X-axis direction by moving a feed finger base plate 130 to which the feed finger 110 is indirectly connected. To achieve this, in this embodiment the first motion unit 300 includes a first motor 302, which in this embodiment is a stepper motor; alternatively, the first motor 302 can be a different motor type known in the art such as a servo motor. A shaft or ball screw 304 is coupled at one end to the motor 302 via a coupler shown generally at 306. The ball screw 304 extends along a rail basket 308 and passes through a slider block 310 with which the ball screw 304 threadedly engages. In this embodiment, the slider block 310 has a shape complementary to that of side rails 312 and 314, and has ball bearings along its sides that engage the side rails 312 and 314, to allow the slider block 310 to slide within the rail basket 308 in the direction of the ball screw 304, i.e., in the X-axis direction. In this embodiment, the slider block 310 is rigidly coupled to a spacer block 320, which in turn is rigidly coupled to a lower surface of the feed finger base plate 130, to which the feed finger 110 is indirectly connected. Consequently, rotation of the first motor 302 extends or retracts the ball screw 304, which moves the slider block 310 and thus the entire finger feed base plate 130 in the X-axis direction, thereby moving the feed finger 110 in the X-axis direction.

In this embodiment, the first motion unit 300 further includes a limiter shown generally at 150 in Figure 2, which limits the motion of the feed finger 110 in the X-axis direction. In this embodiment, the limiter 150 includes a moveable stopper 152 engageable with a fixed bumper 154. The fixed bumper 154 is bolted to the same surface as the first motion unit 300 and does not move relative to the rail basket 308 of the first motion unit; the location at which the fixed bumper 154 is mounted serves to define a maximum travel distance in the X-direction for the feed finger 110. The moveable stopper 152 has a linear recess 156 which is complementary to the protruding shape of a dead stop block 158 connected to the fixed bumper 154, so that when the feed finger 110 reaches its maximum desired travel distance in the X-direction, the moveable stopper 152 abuts against the dead stop block 158 of the fixed bumper, thereby preventing the feed finger from moving further away from the motor 302 in the X-direction. In this embodiment, the first motion unit 300 further includes side baffles 330 shown in Figure 3, for reducing the likelihood of fluid contamination of the rail basket 308. Also, if desired, extendable accordion-style barriers (not shown) may be provided on either side of the slider block 310 and spacer block 320, to keep metal filings, dust or other contaminants out of the rail basket 308. Z-Motion Unit of the Feed Finger Assembly

Referring to Figures 1 , 4 and 5, to move the feed finger 110 in the second degree of freedom, in this embodiment the second motion unit 400 is configured to rotate the feed finger about a second axis. More particularly, in this embodiment the second axis is denoted as the Y-axis and extends horizontally in a direction normal to the plane of the saw blade. Thus, in this embodiment the first axis (X-axis) and the second axis (Y-axis) are orthogonal.

More particularly, in this embodiment the second axis is the central axis of a cylindrical shaft 402 shown in Figure 4. In this embodiment, the upper plate

140 of the feed finger assembly 100 to which the feed finger 110 is mounted is rigidly coupled to the cylindrical shaft 402 via two inverted pillow blocks 404 and 406. The pillow blocks 404 and 406 are rigidly mounted to the bottom side of the upper plate 140 at opposite sides (front and rear) thereof, and are rigidly coupled to opposite end regions of the cylindrical shaft 402, such that the shaft does not rotate relative to the upper plate 140, but rather, the upper plate 140 and the shaft 402 rotate in tandem. The cylindrical shaft 402 passes through a rotational bushing assembly 440, which in this embodiment is a Thomson linear bearing having oilless bushings that allow the cylindrical shaft 402 to freely rotate about and slide along its central axis. Thus, in this embodiment the entire upper plate 140, and thus the feed finger 110 connected to the upper plate, are both pivotable about and slidable along the central axis of the cylindrical shaft 402 (Y-axis).

In this embodiment, housed within a motor casing 409 is a second motor 410, which in this embodiment includes a stepper motor, mounted to the upper plate 140; alternatively, the second motor 410 can be a different motor type known in the art such as a servo motor. The motor 410 rotates a motor shaft 412 which extends downward through an elongated opening 430 in the upper plate 140, which is elongated in the left-right direction as shown in Figure 5. Referring back to Figure 4, the motor shaft 412 extends downward through this elongated opening 430, and is threadedly coupled to a bushing base plate 414, to which a rotational bushing assembly 416 is bolted. In this embodiment, the rotational bushing assembly 416 is a Thomson linear bearing comprising oilless bushings that allow it to freely rotate about and slide along the second cylindrical shaft 418. The second cylindrical shaft 418 is rigidly coupled at its ends to two pillow blocks 420 and 422, which in turn are rigidly mounted to the feed finger base plate 130. In this embodiment, the motor 410 has an internal spinning thread (not shown) which causes the motor shaft 412 to axially extend and retract from the motor 410 without rotating about its axis. More particularly, in this embodiment the motor 410 includes a Thomson Motorized Lead Screw Stepper Motor Linear Actuator, Model No. ML23A300N having a rotating nut configuration, in which the motor rotates an internal threaded nut (not shown) to extend or retract the motor shaft 412 without rotating the motor shaft 412. Thus, when the motor 410 extends or retracts the motor shaft 412, the motor 410 and upper plate 140 either rise or fall relative to the bushing base plate 414, thereby causing the entire upper plate 140 to pivot about the cylindrical shaft 402, thereby causing the feed finger 110 to rotate about the cylindrical shaft 402.

Moreover, the rotational bushing assembly 416 co-operates with the elongated opening 430 in the upper plate 140 through which the motor shaft

412 extends, to allow the motor 410 and motor shaft 412 to slightly pivot about the second cylindrical shaft 418 as the upper plate 140 pivots about the cylindrical shaft 402. This approach allows the motor 410 and motor shaft 412 to effectively remain along an arc centered about the cylindrical shaft 402, rather than attempting to force the motor and shaft to remain vertical as the upper plate 140 pivots. This approach advantageously avoids mismatch between vertical motion of the motor and arcuate motion of the upper plate, and the corresponding wear, jamming or backlash that could result from such a mismatch. Referring to Figures 2, 4, 8 and 12, in this embodiment, the second motion unit 400 further includes an upper plate elevation sensor 450. More particularly, in this embodiment the sensor 450 includes a photomicrosensor comprising two spaced apart plates, one of the plates transmitting infrared light along the y-axis direction to the other. The sensor 450 is affixed to the rotational bushing assembly 416, which in turn is connected to the feed finger base plate 130 via the second cylindrical shaft 418 and the pillow blocks 420 and 422. A horizontal side of an L-shaped bracket 452 is attached to the bottom surface of the upper plate 140 adjacent the second motor 410, such that the vertical side of the "L" extends vertically downward. When the feed finger 110 is in its highest position, which corresponds to the lowest possible position of the second motor 410, the L-shaped bracket blocks the infrared light from being transmitted between the two plates of the sensor 450. As the feed finger 110 is moved to a lower position by pivoting the feed fingertip 114 downward about the cylindrical shaft 402, the motor 410 and upper plate 140 rise further away from the rotational bushing assembly 416 and sensor 450, until the L-bracket attached to the upper plate 140 no longer blocks the infrared transmission between the plates of the photomicrosensor. If desired, the photomicrosensor may have two or more pairs of transmitter/receiver plates at different heights, to yield more refined information about the current height of the feed finger 110 based on how many of the transmitter/receiver pairs are currently being blocked by the L-bracket. Alternatively, assuming the initial positions of the upper plate 140 and feed finger 110 are known, a more precise determination of the current height of the feed finger 110 can be obtained from the records of the second motor 410 itself with respect to the up and down steps that it has taken.

Referring back to Figures 1 and 4, in this embodiment, in view of the fact that the feed finger shaft 112 is expected to be closer to horizontal than to vertical in normal operation, it will be appreciated that the pivotal or rotational motion of the feed fingertip about the Y-axis (cylindrical shaft 402) is in some ways similar to vertical motion along a Z-axis that is orthogonal to both the X- and

Y-axes. When the feed finger shaft 112 is precisely horizontal, all of its rotational motion about the cylindrical shaft 402 is in the Z-axis direction; more generally, as the feed finger shaft 112 pivots about the cylindrical shaft 402 by a nonzero angle Θ away from horizontal, the Z-axis component of the motion of the feed fingertip 114 will be equal to the magnitude of its arcuate motion multiplied by COS(O). Consequently, as a hypothetical example, if the feed finger 110 is angled by no more than about 25 degrees from horizontal, then the Z-axis component of the motion of the feed fingertip 114 will exceed 90% of its total arcuate motion.

It will therefore be recognized that the approach of the present embodiment, by enabling the feed fingertip 114 to rotate about the Y-axis, is merely one example of a way in which the second degree of freedom may be provided to the feed fingertip. For example, in an alternative embodiment, the second degree of freedom may include linear translation in the Z-axis direction, so that the first, second and third motion units 300, 400 and 500 are configured to linearly translate the feed finger along a first axis, a second axis and a third axis, respectively, wherein the axes are orthogonal. More particularly, to achieve this, one such alternative embodiment involves: removing the second cylindrical shaft 418, the rotational bushing assembly 416 and the pillow blocks 420 and 422, and replacing them with a simple rigid threaded mounting block, so that extension or retraction of the motor shaft 412 by the motor 410 vertically raises and lowers the upper plate 140; detaching and decoupling the upper plate 140 from the cylindrical shaft 402; and moving both the motor 410 and threaded mounting block closer to the center of the upper plate 140.

Y-Motion Unit of the Feed Finger Assembly

Referring to Figures 1 , 4 and 5, in this embodiment the third motion unit 500 is configured to linearly translate the feed finger 110 in a direction having a nonzero component normal to a plane of the saw blade.

More particularly, in this embodiment the third motion unit 500 is configured to linearly translate the feed finger 110 along a third axis, which in this embodiment is a normal to a plane of the saw blade 120. Thus, in this embodiment the second axis about which the second motion unit 400 provides rotational motion and the third axis about which the third motion unit 500 provides translational motion are parallel. ln this embodiment, the third motion unit 500 shares some components with the second motion unit 400, including the pillow blocks 404 and 406 that provide rigid connections between the upper plate 140 and the cylindrical shaft 402 as described above, and the rotational bushing assembly 440 which is rigidly connected to the feed finger base plate 130. In this embodiment, the rotational bushing assembly 440 not only permits the cylindrical shaft 402 to rotate therein as described above in connection with Z-motion, but also permits the cylindrical shaft 402 to slide in its axial direction (Y-motion), at least until one of the pillow blocks 404 or 406 abuts the rotational bushing assembly 440.

In this embodiment, the third motion unit 500 further includes a third motor 502, which in this embodiment includes a stepper motor that extends and retracts a motor shaft 504 along the axial direction of the cylindrical shaft 402; alternatively, the third motor 502 can be a different motor type known in the art such as a servo motor. In this embodiment, the motor shaft 504 extends rearward from the third motor 502 through a stepper flange plate 506, then ends at a threaded cylindrical tip portion (not shown) having a narrower diameter than the remainder of the motor shaft 504. Also in this embodiment, the cylindrical shaft 402 has a complementary aperture defined at its front end, the complementary aperture comprising an outer wider-diameter aperture portion to accommodate a main portion of the motor shaft 504, followed by an inner narrower-diameter aperture portion to accommodate the narrower tip of the motor shaft 504. The tip portion of the motor shaft 504 is threadedly engaged with threads of the inner narrower-diameter aperture portion of the cylindrical shaft 402, and is secured therein by a double nut (not shown). In this embodiment, as with the second motor 410, the third motor 502 has an internal spinning thread (not shown) which allows it to extend and retract the motor shaft 504 without rotating the motor shaft 504 about its central axis. More particularly, in this embodiment the motor 502 includes a Thomson Motorized Lead Screw Stepper Motor Linear Actuator, Model No. ML23A300N having a rotating nut configuration, in which the motor rotates an internal threaded nut (not shown) to extend or retract the motor shaft 504 without rotating the motor shaft 504. The motor shaft 504 can, however, rotate within the internal nut of the motor when necessary, in order to accommodate the small range of rotational motion that would tend to occur when the Z-motion unit 400 pivots the upper plate 140, pillow blocks 404 and 406 and cylindrical shaft 402 in tandem about the central axis of the cylindrical shaft 402 as described above, with the rotation of the cylindrical shaft 402 driving a corresponding rotation of the motor shaft 504 within the internal threaded nut of the motor 502. Thus, when the third motor 502 pushes the motor shaft 504 in the Y-axis direction toward the rotational bushing assembly 440, the motor shaft 504 pushes against the complementary aperture of the cylindrical shaft 402, thereby sliding the cylindrical shaft 402 in its axial direction through the rotational bushing assembly 440. It will be recalled that the entire upper plate 140 is rigidly coupled to the cylindrical shaft 402 via the pillow blocks 404 and 406, and is otherwise supported only through the rotational bushing assembly 416 which is coupled to, but free to rotate about and slide along, the second cylindrical shaft 418, which is parallel to the cylindrical shaft 402. Consequently, actuation of the third motor 502 to extend or retract the motor shaft 504 in the Y-axis direction toward or away from the rotational bushing assembly 440 causes the entire upper plate 140, including the feed finger 110, to slide in the Y-axis direction.

In this embodiment, the third motion unit 500 further includes a proximity sensor 510, for detecting the proximity of the upper plate 140 as it slides along the Y-axis. Alternatively, assuming the initial position of the upper plate 140 is known, the current position of the upper plate 140 along the Y-axis can be determined more precisely from records of the cycles completed by the third motor 502. Referring to Figures 8, 11 and 12, in this embodiment the second and third motion units 400 and 500 each include a number of protective skirts such as those shown at 460.

Tooth Detection Unit The tooth detection unit 200 comprises an object detection sensor having the aforementioned emitter 202 and detector 204, and a signal processor (not shown). In the embodiments described herein, the object detection sensor is an optical sensor of the types known in the art, such as photoelectric sensors, fibre optic sensors and laser sensors. However, other types of object detection sensors known in the art can be substituted, such as inductive proximity sensors, wherein the magnetic field properties will change as the inductive sensor changes position relative to a metal target such as a metal, carbide or Stellite tip saw tooth, or a capacitive type proximity sensor.

In the described embodiments, the optical sensor is a reflective type wherein light emitted from the emitter 202 is reflected off a target object (i.e. the tooth) and detected by the detector 204 that is located beside the emitter 202. Alternatively, the optical sensor can be an opposed type of sensor wherein the emitter 202 is mounted on the feed finger 110 on one side of a saw blade and the detector 204 is mounted on the feed finger 110 (e.g. via an arm) on the other side of the saw blade.

Fiber optic sensors are particularly suitable for use in the tooth detection unit 200. Such fiber optic sensors use optical fiber either as the sensing element or as a means for relaying signals from a separate sensor to the signal processor. One suitable commercially available fiber optic sensor is the FU series of fiber optic sensors manufactured by Keyence, including the FU-66TZ reflective fiber unit as the emitter 202, and the FS-N11 MN fiber amplifier as the detector 204. As can be seen in Figure 13D, the emitter 202 and detector 204 are mounted within a channel in the feed finger shaft 112, such that the light emitting part of the emitter 202 and the light detecting part of the detector 204 are beside each other in close proximity and are facing the saw blade. In particular, the position of the emitter 202 is located a selected distance from the feed fingertip 114 such that when the emitter 202 is facing a gullet ("first gullet" or "sensor aligned gullet") of a saw blade having a known diameter and tooth profile, the spatial position of the feed fingertip 114 relative to another gullet ("target gullet" or "feed fingertip aligned gullet") is known, and the feed finger 110 can move the feed fingertip 1 14 into alignment with the target gullet if they are not already aligned.

The tooth detection unit 200 includes an air jet (not shown) comprising a nozzle mounted on the feed finger 112 in proximity to and facing the detector 204. The nozzle is fluidly coupled to a pressurized air source (not shown) and the air jet is operated during a sharpening operation to discharge a flow of air against the detector 204 surface to keep it clean.

The emitter 202 and the detector 204 are communicative with the signal processor, either by wire or wirelessly. The signal processor can be a separate hardware unit mounted in a suitable location in the feed finger assembly 100 or elsewhere in the saw sharpening machine. Alternatively, the functionality of the signal processor can be integrated into a central processing unit (CPU, not shown) of the saw sharpening machine that is programmed with Computer Numeric Controller functionality to perform saw grinding operations. The signal processor (or CPU) comprises a memory having program code stored thereon that is executable by the signal processor to perform a tooth detection operation by the tooth detection unit 200 ("tooth detection program code"), and as described in more detail below, the CPU also executes program code that performs a tooth indexing operation wherein the feed finger assembly 100 rotates the saw blade 120 and advances a target tooth of the saw blade 120 into a position for grinding ("tooth indexing program code").

Referring to Figure 14, the tooth detection program code when executed by the signal processor performs the following steps: step 210: Activate emitter 202 and detector 204 of the optical sensor; step 212: Advance feed finger 110 in a direction parallel to saw blade (i.e.

move in X and Z directions) such that the emitter 202 and detector 204 follow the circumference of the saw and moves past the expected location of the first gullet and adjacent tooth ("first tooth") by a preset amount that is at least the distance between adjacent teeth; step 214: Retract feed finger in a direction parallel to saw blade (i.e. move in X and Z directions) such that the emitter 202 and detector 204 follow the circumference of the saw blade and move by an increment that at a minimum travels the distance between adjacent teeth on the saw blade; read detector 204 multiple times as the feed finger is retracted to receive reflected light measurement values; select minimum and maximum measurement values from the detector readings and use these values to calculate a suitable detection threshold, wherein the minimum measurement value represents a gullet aligned with the detector 204 (minimal reflection) and a maximum measurement value represents a tooth aligned with the detector 204 (maximum reflection) ; step 216 If the detector 204 reads a measurement value that is at or above the detection threshold, the emitter 202 is still facing at least part of the first tooth and thus is not aligned; continue retracting feed finger 110 and reading detector 204; step 218: if the detector 204 reads a measurement value that is below the detection threshold, the emitter 202 is aligned with the first gullet and the spatial relationship between the feed fingertip 114 and the saw blade can now be determined; the feed finger retracting is stopped and the process advances to step 220; and step 220: execute the tooth indexing operation to cause the feed finger

110 to rotate the saw blade and advance (index) a target tooth into position for grinding.

When saw blades of different diameter and/or tooth count are mounted in the saw sharpening machine, the feed fingertip 114 will not necessarily be aligned with the target gullet when the optical sensor is aligned with the first gullet. Therefore, the signal processor (or CPU) is further programmed with program code to receive an indication of the type of saw blade being serviced, and then determine the location of the feed fingertip 114 relative to the target gullet based on the optical sensor being in alignment with the first gullet, by using the indication of saw blade type to determine the location of the target gullet relative to the first gullet, and using the known location of the feed fingertip 114 relative to the optical sensor. The CPU then is programmed to move the feed finger 110 and align the feed fingertip 114 with the target gullet after the emitter 202 has been aligned with the first target gullet.

Instead of the tooth detection operation detecting a gullet in order to determine the position of a saw tooth, the tooth detection unit can be configured to detect a saw tooth according to an alternative embodiment. More particularly, the tooth detection program code can be modified such that when the detector detects a reflected light signal at or above the detection threshold, this indicates that the optical sensor is aligned with the first saw tooth, and the position of the feed fingertip 114 relative to the target gullet can be determined in a similar manner as discussed above.

Operation of the Feed Finger Assembly and Tooth Detection Unit Referring to Figures 1 , 6 and 7, in this embodiment, the feed finger assembly 100 is configured to perform a tooth indexing operation that indexes each tooth of the saw blade 120 into position for grinding by the saw sharpening machine, wherein the tooth indexing operation comprises at least a side-shift cycling mode as shown in Figure 6. Alternatively, the feed finger assembly can perform the tooth indexing operation using other cycling modes such as an over-the-top cycling mode such as shown in Figure 7. The tooth indexing operation is performed in conjunction with the tooth detection operation, such that the feed fingertip 114 is precisely and automatically aligned with the gullets of the saw blade.

When performing the tooth indexing operation using the side-shift mode as shown in Figure 6, at least the third motion unit 500 is configured to move the feed fingertip 114 of the feed finger 110 in at least the third degree of freedom into and out of a plane of the saw blade 120, to laterally engage with and disengage from a gullet 122 of the saw blade 120, respectively.

A computer readable medium such as a computer memory is encoded with the tooth indexing program code. The central processing unit acts as a Computer Numeric Controller for the larger saw grinding apparatus and can be provided to execute the tooth indexing program code. As noted previously, the CPU can also execute the tooth detection program code, or this tooth detection operation program code can be stored on and executed by a separate signal processor unit.

Accordingly, and with reference to Figure 15, a computer-readable medium stores the tooth indexing program code which, when executed by the CPU, causes cause the feed finger assembly 100 to carry out the following tooth indexing operation that uses a side-shifting cycling mode:

The side-shift cycling mode is used for positioning the feed finger 110 for engagement with the saw blade 120, and generally involves moving the feed finger 110 in three different degrees of freedom. Referring to Figures 1 , 6 and 7, at least the first motion unit 300 is configured to move the feed fingertip 114 in at least the first degree of freedom to a side position shown in broken outline at 614 in Figure 6. In this embodiment, the side position 614 is proximate to but spaced apart from the gullet 122 by a spacing having a nonzero component in a direction normal to a plane of the saw blade 120.

More particularly, in this embodiment both the first and second motion units 300 and 400 are configured to move the feed fingertip 114 to the side position 614 by moving the feed fingertip 114 in at least the first and second degrees of freedom. More generally, depending on the "home" position of the feed fingertip 114, any linear combination of the first, second and third motion units 300, 400 and 500 may be employed to move the feed fingertip 114 into the side position 614, wherein the feed fingertip is aligned with a gullet in the Y- direction. As noted above, the side position 614 is reached by executing the tooth detection operation to move the feed finger 110 to align the emitter 204 with the first gullet, calculate the location of the feed fingertip 114 relative to the target gullet, and then move the feed fingertip 114 into alignment with the target gullet (shown as 122 in Figure 7).

As discussed earlier herein, the first degree of freedom comprises X-axis motion in a length direction parallel to the plane of the saw blade 120, the third degree of freedom comprises linear Y-axis motion in a width direction normal to the plane of the saw blade, and the second degree of freedom has a Z-axis motion component in a height direction orthogonal to the length and width directions. More particularly, in this embodiment the second degree of freedom comprises rotational motion about an axis parallel to the width direction, wherein the feed fingertip 114 follows an arcuate path having the Z- axis motion component.

In this embodiment, once the feed fingertip 114 is in the side position 614, at least the third motion unit 500 is configured to move the feed fingertip 114 in at least the third degree of freedom from the side position 614 into the gullet 122 (step 222 in Figure 15). Advantageously, by combining linear side-shift engagement with the precision of computer numeric control and the automated alignment of the feed fingertip 114 with a gullet by the tooth detection operation, the engagement of the feed fingertip 114 can be precisely controlled in a repeatable manner. The combination of the availability of three degrees of freedom including linear Y-axis motion, with the precise motion control provided by the stepper motors of the feed finger assembly 100, allows the feed fingertip 114 to always engage the precise center of the gullet and tooth, and the angled orientation of the feed fingertip ensures that such a precisely centered engagement is possible even when the teeth of the saw blade have shear angles or alternating shear angles, as discussed earlier herein.

In this embodiment, only linear translational motion in the Y-axis direction is employed to move the feed fingertip 114 from the side position 614 into the target gullet, and thus only the third motion unit 500 is used for this purpose.

Alternatively, however, in other embodiments the side position 614 may be replaced with an offset side position, offset from the gullet not only in the Y- axis translational direction but also further offset in at least one of the X-axis translational direction and the Y-axis rotational direction (which has a Z-axis translational component). In such alternative embodiments, either or both of the first and second motion units 300 and 400 may co-operate with the third motion unit 500 to move the feed fingertip 114 diagonally from its offset side position into the target gullet 122.

Once the feed fingertip 114 has engaged the target gullet 122 of the saw blade 120, at least one of the first and second motion units 300 and 400 is configured to incrementally advance the feed fingertip 114 in at least one of the first and second degrees of freedom to incrementally advance the saw blade (step 224 in Figure 15). More particularly, in this embodiment at least the first motion unit 300 is configured to incrementally advance the feed fingertip 114 in the X-axis direction (coplanar with the saw blade). If desired, the second motion unit 400 may also co-operate with the first motion unit 300 by simultaneously moving the feed fingertip 114 vertically (by rotating it about the Y-axis) at the same time as the feed fingertip 114 is advancing in the X- axis direction, to cause the feed fingertip 114 to trace out the same arcuate path that the target gullet 122 of the saw blade 120 will follow when it is incrementally advanced.

Once the saw blade 120 has been incrementally advanced by one tooth, at least the third motion unit 500 is configured to disengage the feed fingertip 114 from the target gullet 122 by moving the feed fingertip 114 in at least the third degree of freedom (step 226 in Figure 15). More particularly, in this embodiment the third motion unit 500 moves the feed fingertip 114 along a linear translation in the Y-axis direction out of the target gullet 122 and back into the side position 614. Advantageously, by disengaging the feed fingertip 114 through linear translation in the Y-axis direction, the present embodiment reduces the likelihood that the feed fingertip 114 may inadvertently contact and rotate the saw blade during disengagement, in comparison to conventional systems that disengage the feed fingertip using either motion confined to the X-Z plane of the saw blade 120, or short-radius rotation of the feed fingertip out of the saw blade plane, for disengagement.

After disengagement, at least the first motion unit 300 is configured to retract the feed fingertip 114 by moving the feed fingertip 114 away from the saw blade in at least the first degree of freedom, which in this embodiment is linear translation along the X-axis (step 228 of Figure 15). More generally, retraction may involve moving the feed fingertip 114 to a "home" position, and if the "home" position also differs from the side position 614 in the second and/or third degrees of freedom, then the second and third motion units 400 and 500 also co-operate in retracting the feed fingertip 114 back to its home position. More generally, however, the feed fingertip 114 need not be returned to a "home" position during each cycle, in view of the full programmability of the motion of the feed fingertip 114. In this embodiment the processor is fully programmable to move the feed fingertip 114 to any position in its range of motion. Consequently, the motions of the feed fingertip for a particular cycle are not restricted to linear combinations of the above-described exemplary cycles, but rather, are limited only by the mechanical range of motion of the feed fingertip.

The full programmability of the motion of the feed fingertip 114 is particularly advantageous for saw blades that have variable pitch gullet dimensions on the same blade.

For example, if desired, different alternating motion cycles of the feed fingertip 114 may be used for blades with differently shaped alternating tooth types, with each alternating cycle optimized for a particular respective one of the different alternating tooth types.

Such a full, programmable range of motion over all three degrees of freedom also provides significant advantages over systems in which the feed finger has only one or two degrees of freedom, or systems that provide a third degree of freedom only over a very limited range of motion, such as permitting a wider variety of saw blade types to be processed, and reducing the likelihood of inadvertent rotation of the saw blade when initially engaging and disengaging the feed fingertip 114 within the target gullet 122, as discussed above.

Bar Code Scanning Unit Optionally, and as shown in Figures 2, 4 and 13D, the saw sharpening machine is provided with a saw blade data reader, such as a bar code scanner 250. The bar code scanner 250 is mounted in close proximity to the optical sensor 200 and for example can be mounted on the feed finger 1 10 closer towards or further back from the feed finger tip 114. A saw blade to be sharpened is provided with an electronically-readable data source such as a bar code attached to its side surface that is alignable with the bar code scanner 250 when the saw blade is mounted in the saw sharpening machine. The data source can include information about the saw blade, such as saw blade type, which allows the saw sharpening machine to automatically perform certain operations such as a saw grinding operation on a tooth of the saw blade.

The data reader can be a bar code scanner based on optical sensors known in the art, such as photoelectric sensors, fibre optic sensors and laser sensors. Alternatively, the data reader can use other automatic identification and data capture (ADIC) technologies known in the art, such as radio frequency identification (RFID), magnetic stripe reading, and optical character recognition (OCR). Such technologies incorporate an electronic reader mounted in the feed finger assembly or elsewhere in the saw sharpening machine, and an electronically readable data source on the saw blade.

In the described embodiments, the data reader is a reflective type optical sensor mounted on the feed finger assembly 100, wherein light emitted from an emitter of the scanner 250 is reflected off a target object (i.e. the bar code) and detected by a detector of the scanner 250 that is located beside the emitter. In one embodiment, the bar code emitter is a LED imager such as a linear imager or a full imager comprising multiple LEDs as are known in the art. The detector is a photocell of the type known in the art.

The bar code scanner 250 further comprises a converter (not shown) that converts an analog signal of varying voltage generated by the photocell when the reflected light from the emitter is detected, into a digital signal. This signal is the digital representation of what the detector detected from the reflected light, and if the reflected light was reflected off a bar code, the digital representation will be of the bar code. This digital representation is then decoded by a decoder (not shown), which is program code stored in a memory and executable by a processor such as the CPU of the saw sharpening machine, or the signal processor for the tooth detection unit 200.

The bar code contains information about the saw blade 120, such as the saw blade type (diameter and tooth count). Once the decoder decodes the digital representation of the bar code and determines the saw blade type, the saw sharpening machine can be programmed to determine the type of saw sharpening operation for the saw blade 120. Then, a sharpening operation can be automatically carried out, such as a top grinding, face grinding, and/or side grinding operation as described in PCT publication no. WO 2013/091 1 10. Referring to the saw grinding apparatus described in PCT publication no. WO 2013/091 1 10, the decoder can cause the saw sharpening machine to execute a Computer Aided Manufacturing (CAM) program to carry out a grinding procedure for a grinding operation. In addition to a grinding procedure for each grinding operation, the CAM program also includes a procedure for changing grinding tools. That is, a tool changing procedure is executable by the processor of the saw sharpening machine to extract commands to obtain a grinding wheel from a tool bay in the grinding machine that is appropriate for the next grinding operation, and to return that tool back to the tool bay after the grinding operation has been completed.

Alternatively or additionally, a temporary bar code (not shown) may be applied to one or more specific teeth to indicate that a different set of operations are to be applied the specifically identified teeth. The tooth detection apparatus 200 can be programmed to move the feed finger 110 such that the bar code scanner 250 reads and decodes the temporary bar code, and provides information from the temporary bar code to the saw sharpening machine to carry out a specified grinding operation on the tooth or teeth associated with the temporary bar code. While specific embodiments of the invention have been described and illustrated, such embodiments should be considered illustrative of the invention only and not as limiting the invention as defined by the accompanying claims. For example, while the described embodiments describe a saw sharpening machine comprising a tooth detection unit having an object detection sensor with an optional saw blade data reader mounted to a feed finger assembly, alternative embodiments can include a tooth detection unit having a saw blade data reader with an optional object detection sensor mounted to the feed finger assembly.

Claims

What is claimed is:

1 . A method for determining a position of a saw blade mounted in a saw sharpening machine, comprising:

(a) positioning an object detection sensor beside an outer edge of a saw blade such that the object detection sensor faces a row of alternating saw teeth and gullets on the outer edge of the saw blade;

(b) moving the object detection sensor relative to the row of alternating saw teeth and gullets until the object detection sensor is in an aligned position wherein the object detection sensor faces and detects a first tooth or a first gullet; and

(c) determining a position of the first tooth or the first gullet from the aligned position of the object detection sensor.

2. The method as claimed in claim 1 wherein the object detection sensor is selected from a group consisting of: optical sensors, inductive sensors, and capacitive proximity sensors

3. The method as claimed in claim 2 wherein the object detection sensor is an optical sensor selected from a group consisting of: photoelectric sensors, fiber optic sensors, and laser sensors.

4. The method as claimed in claim 3 wherein the optical sensor is a reflective type and comprises an emitter and an adjacent detector, wherein both face the saw blade.

5. The method as claimed in any of claims 1 to 4 wherein the object detection sensor is affixed to a feed finger of the saw sharpening machine at a known location relative to a feed fingertip of the feed finger, and the method further comprises: moving the feed finger until the object detection sensor is in the aligned position with the first tooth or first gullet; determining the position of a feed fingertip of the feed finger relative to a target gullet of the saw blade, wherein the location of the target gullet relative to the first gullet or the first tooth is known and the location of the feed fingertip relative to the object detection sensor is known; and moving the feed finger until the feed fingertip is aligned with the target gullet.

6. The method as claimed in claim 5 wherein the step of moving the feed finger comprises: advancing the feed finger in a direction parallel to the saw blade such that the object detection sensor moves past an expected location of the first gullet and the first tooth; reading the object detection sensor and retracting the feed finger in a direction parallel to the saw blade and until the objection detection sensor does not detect a signal above a detection threshold, and stop retracting the feed finger and indicate that the object detection sensor is in the aligned position.

7. The method as claimed in claim 6 further comprising after the feed fingertip is aligned with the target gullet: inserting the feed fingertip into the target gullet, advancing the feed finger to move the saw blade, withdrawing the feed fingertip out of the target gullet, and retracting the feed finger into a home position.

8. The method as claimed in claim 1 further comprising positioning a saw blade data reader in proximity to an electronically readable data source on the saw blade, and reading data stored on the data source.

9. The method as claimed in claimed 8 wherein the saw blade data reader is a bar code scanner and the electronically readable data source is a bar code.

10. The method as claimed in claim 9 wherein the data stored on the bar code includes information about the saw blade, and the method further comprises decoding the data and executing a computer aided manufacturing program to perform a saw grinding operation on the saw blade using the decoded information.

1 1 . An apparatus for determining a position of a saw blade mounted in a saw sharpening machine, comprising:

(a) an object detection sensor located beside an outer edge of the saw blade such that the object detection sensor faces a row of alternating saw teeth and gullets on the outer edge of the saw blade;

(b) one or more motors coupled to the object detection sensor such that actuation of the one or more motors moves the object detection sensor relative to the saw blade; and

(c) a processor and a memory having encoded thereon program code executable by the processor to: operate the one or more motors to move the object detection sensor relative to the row of alternating saw teeth and gullets until the object detection sensor is in an aligned position wherein the object detection sensor faces and detects a first tooth or a first gullet; and determine a position of the first tooth or the first gullet from the aligned position of the object detection sensor.

12. The apparatus as claimed in claim 1 1 wherein the object detection sensor is selected from a group consisting of: optical sensors, inductive sensors, and capacitive proximity sensors.

13. The apparatus as claimed in claim 1 1 wherein the object detection sensor is an optical sensor selected from a group consisting of: photoelectric sensors, fiber optic sensors, and laser sensors.

14. The apparatus as claimed in claim 13 wherein the optical sensor is a reflective type and comprises an emitter and an adjacent detector, wherein both face the saw blade.

15. The apparatus as claimed in any of claims 1 1 to 14 wherein the one or more motors comprises one or more feed finger motors coupled to a feed finger of the saw sharpening machine, the object detection sensor is affixed to the feed finger at a known location relative to a feed fingertip of the feed finger, and the program code is further executable by the process to: operate the one or more feed finger motors to move the feed finger relative to the row of alternating saw teeth and gullets until the object detection sensor is in the aligned position, and determine the position of the feed fingertip relative to a target gullet, wherein the position of the target gullet and the first tooth or the first gullet is known.

16. The apparatus as claimed in claim 15 wherein the program code is further executable by the processor to: operate the one or more feed finger motors to advance the feed finger in a direction parallel to the saw blade such that the object detection sensor moves past an expected location of the first gullet and the first tooth, and retract the feed finger in a direction parallel to the saw blade by an increment that is less than the present amount; read the object detection sensor and retract the feed finger in a direction parallel to the saw blade and until the objection detection sensor does not detect a signal above a detection threshold, and stop retracting the feed finger and indicate that the object detection sensor is in the aligned position.

17. The apparatus as claimed in claim 16 wherein after the program code has been executed and indicates that the object detection sensor is in the aligned position, the program code is further executable by the processor to: operate the one or more feed finger motors to move the feed finger until the feed fingertip is aligned with the target gullet, insert the feed fingertip into the target gullet, advance the feed finger to move the saw blade, withdraw the feed fingertip out of the target gullet, and retract the feed finger into a home position.

18. The apparatus as claimed in claim 1 1 further comprising a bar code scanner positioned to face a bar code on the saw blade, and operable to read data stored on the bar code.

19. The apparatus as claimed in claim 18 wherein the data stored on the bar code includes information about the saw blade, and the program code is further executable to decode the data and execute a computer aided manufacturing program to perform a saw grinding operation on the saw blade using the decoded information.

20. The apparatus as claimed in claim 15 further comprising an air jet assembly comprising an air jet nozzle mounted on the feed finger and facing the object detection sensor, and a pressurized air source fluidly coupled to the air jet nozzle.