US20120100780A1

US20120100780A1 - Improved abrasive saw

Info

Publication number: US20120100780A1
Application number: US13/266,541
Authority: US
Inventors: John L. Weingart; Lawrence L. Freson; Michael F. Hart; Arnold Buchanan
Original assignee: Illinois Tool Works Inc
Current assignee: Illinois Tool Works Inc
Priority date: 2009-05-01
Filing date: 2010-04-01
Publication date: 2012-04-26
Also published as: JP2012525270A; WO2010126678A3; CN102413978A; EP2429749A2; EP2429749B1; WO2010126678A2

Abstract

An abrasive saw having an associated cutting wheel is used for cutting objects. The saw includes a base, a cutting assembly operably mounted to the base and a controller. The cutting assembly includes a pivot shaft, a drive shaft operably mounted to the pivot shaft, a drive, and a drive wheel. A flexible drive element operably connects the drive shaft and a drive wheel. The distance between the drive wheel axis of rotation and the drive shaft axis of rotation is variable to increase or decrease a tension in the flexible drive element. A feed table is operably mounted to the base and is movable forward and rearward in a direction of rotation of the associated cutting wheel. The cutting wheel is lockable in the cutting position and the feed table, with the object secured thereto, is moved, by the controller toward the associated cutting wheel to cut the object. An enclosure encloses the cutting assembly and has stationary sides and openable front and top panels hingedly mounted to one another and to a portion of one of the side panels to open as a unitary assembly for access to the cutting assembly.

Description

CROSS-REFERENCE TO RELATED APPLICATION DATA

This application is national phase of PCT/US2010/029619 filed Apr. 1, 2010, and claims the benefit of priority of Provisional U.S. Patent Application Ser. No. 61/174,560, filed May 1, 2009.

BACKGROUND OF THE INVENTION

The present invention relates to an abrasive saw. More particularly, the present invention relates to an improved abrasive saw having novel blade and sample drive systems, improved working area/sample access, wear components, and sensor and control features.
Abrasive saws are used in various industries, but in particular are used in the rough or gross preparation of samples/specimens for examination. For example, specimens such as metals or aggregates (concrete) are often microscopically examined to determine grain structure, composition, failures and the like.
In preparing samples, the samples typically must be cut, polished and mounted for examination. The first part of that preparation process, the cutting, is carried out using a saw. Often, the saw is of the abrasive type (that is, it uses an abrasive wheel in lieu of a toothed blade) and is carried out in a wet process to lubricate, cool and flush the sample and abrasive wheel.
Known saws uses a wheel that is mounted to a pivoting arm that is pulled or urged downward into the sample to perform the cut. The sample is fixedly mounted and secured to a plate or bed of the saw. Among other things, this can result in too great of a force being exerted on the sample (and the blade) which can overheat the sample and blade. This can also result in excessive stress on the saw motor.
In known saws, if serial samples are required to be cut from the same specimen, the specimen must be unsecured (unclamped) from the bed, moved to a proper location beneath the saw blade, and resecured (reclamped) to the bed to carry out the next serial or sequential cut.
In addition, such known saws are often belt driven, but do not have ready means for adjusting the belt to assure proper tension for blade drive.
Accordingly, there is a need for an improved abrasive saw. Such a saw has novel wheel and samples drive systems to improve the mobility of the specimen on the saw bed and to assure good and smooth contact between the abrasive wheel and the sample. Desirably, such a saw also has improved working area/sample access, wear components, and sensor and control features.

SUMMARY OF THE INVENTION

An abrasive saw has a cutting wheel for cutting objects mounted thereto, The saw includes a base, a cutting assembly operably mounted to the base and a controller. The cutting assembly includes a pivot shaft, a drive shaft operably mounted to the pivot shaft, a drive, and a drive wheel. The drive is operably connected to the drive shaft and the drive shaft is operably connected to the drive wheel by a flexible drive element or belt to rotate the drive wheel. The drive wheel has the cutting wheel mounted thereto. The pivot shaft is pivotable to move the cutting wheel between a cutting position and a disengaged position.
The drive shaft has an axis of rotation and the drive wheel has an axis of rotation spaced a distance from the drive shaft axis of rotation. The flexible drive element spans the distance between the drive wheel axis of rotation and the drive shaft axis of rotation. The distance between the drive wheel axis of rotation and the drive shaft axis of rotation is variable to increase or decrease a tension in the drive belt.
In a present saw, the drive shaft is disposed within the pivot shaft and rotation of the pivot shaft varies the distance between the drive wheel axis of rotation and the drive shaft axis of rotation. The pivot shaft has a longitudinal axis and the distance between the pivot shaft longitudinal axis and the drive wheel axis of rotation is fixed. The drive shaft is eccentrically disposed within the pivot shaft. Varying the distance between the drive wheel axis of rotation and the drive shaft axis of rotation varies the tension in the belt.
In a present embodiment, the saw includes a feed table operably mounted to the base. A drive is operably connected to the feed table. The feed table is movable forward and rearward in a direction of rotation of the associated cutting wheel to move the object toward and away from the cutting wheel. The cutting wheel is lockable in the cutting position and the feed table, with the object secured thereto, is moved, manually or by operation of the controller, toward the cutting wheel to cut the object.
The saw includes a current sensor circuit that generates a signal to the controller and, upon sensing a predetermined current, the controller slows and/or stops the drive to slow and/or stop movement of the table toward the associated cutting wheel. The controller includes an input for inputting the speed of the table moving toward the associated cutting wheel.
The saw also includes a transverse drive to move the feed table transverse to the direction of rotation of the associated cutting wheel for serially cutting objects. The transverse drive is manually operated.
The saw includes an enclosure enclosing the cutting assembly. A present enclosure has a fully stationary side and an openable front and top panel. A portion of one of the side panels is movable and is operably connected to the front and top panels. The front and top panels are hingedly mounted to one another to open as a unitary assembly along with the portion of the side panel. The assembly is openable to provide access to the cutting assembly.
The enclosure includes at least one wear element disposed on the inside of the enclosure, aligned with the direction of rotation of the associated cutting wheel, to prevent erosion of the enclosure.
One or more interlocks prevent operation of the abrasive saw when the enclosure is open. A fluid feed is provided to feed fluid to a shroud covering the cutting wheel.
These and other features and advantages of the present invention will be apparent from the following detailed description, in conjunction with the appended claims.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

The benefits and advantages of the present invention will become more readily apparent to those of ordinary skill in the relevant art after reviewing the following detailed description and accompanying drawings, wherein:

FIG. 1 is a perspective front view of the improved abrasive saw embodying the present invention, the saw shown with the viewing hood removed for clarity of illustration;

FIG. 2 is a side view of the saw with a portion of the cover removed to show the drive system;

FIG. 3 is a perspective view of the saw wheel arm and drive components;

FIG. 4 is side view of the saw wheel arm showing the eccentric relationship between the drive shaft, pivot shaft and final drive wheel;

FIG. 5A is an enlarged front view of the saw, showing the saw wheel arm in the engaged or cutting position;

FIG. 5B is a view similar to that if FIG. 5A with arm in the disengaged position;

FIG. 6 is a view looking into the drive region and showing the actuating handle and linkage for moving the saw wheel arm between the engaged and disengaged positions;

FIG. 7 is an enlarged view of the arm lock assembly;

FIG. 8 is a view looking transverse along the front of the saw illustrating the feed drive system;

FIG. 9 is a view looking into the saw front and showing the screw drive assembly for the table;

FIG. 10 is a perspective view of the viewing/protective hood in the open position;

FIG. 11 in an exploded view showing the pivot shaft, drive shaft and pivot arm linkage;

FIG. 12 is an exploded view of the X-drive;

FIGS. 13A-D show an electrical line drawing for the saw;

FIG. 14 is a wiring diagram for the saw showing the current sensor; and

FIG. 14A is an enlarged view of a part of FIG. 14.

DETAILED DESCRIPTION OF THE INVENTION

While the present invention is susceptible of embodiment in various forms, there is shown in the drawings and will hereinafter be described a presently preferred embodiment with the understanding that the present disclosure is to be considered an exemplification of the invention and is not intended to limit the invention to the specific embodiment illustrated.
It should be further understood that the title of this section of this specification, namely, “Detailed Description Of The Invention”, relates to a requirement of the United States Patent Office, and does not imply, nor should be inferred to limit the subject matter disclosed herein.
Referring now to the figures and in particular, to FIG. 1, there is shown an improved abrasive saw 10 embodying the principles of the present invention. In this illustration, the saw is shown with the hood and abrasive wheel removed for clarity of illustration. The saw 10 includes, generally, a base 12, a cutting region 14 with an abrasive wheel arm assembly 16 and a feed bed 18, a drive region 20 and a control panel 22.
The drive region 20 is shown in FIG. 2. A wheel drive motor 24 (cutting wheel motor) is connected to a drive shaft 26 that is mounted within a pivot arm assembly 28. A pair of toothed wheels 30, 32 (one on the motor 24 and the other on the shaft 26) and a toothed drive belt 34 permit the transfer of power from the motor 24 to the drive shaft 26. A drive wheel 36 (also toothed) is mounted to the opposite end of the drive shaft 26.
Referring also to FIGS. 2-4 and 6, the drive shaft 26 is mounted within a pivot shaft 38. The pivot shaft 38 is held within a set of bearings 40 to allow the shaft 38 to pivot (rotate) to move the saw wheel W between the disengaged and engaged (cutting) positions. A linkage 42 is used to move (pivot) the shaft 38. An L-shaped arm 44 is mounted at about the heel 46 to pivot. A handle 48 is mounted to one leg 50 of the L-arm 44 and a link bar 52 is mounted to the other leg 54. A lock or brake system 56 is mounted between the saw frame or base 12 and the handle leg 50 of the L-arm 44. The brake 56 is used to lock the linkage 42 into any position once the brake 56 is engaged.
Mounted to the opposite end of the link bar 52 is a pivot shaft clamp 58. The pivot shaft clamp 58 is secured to the pivot shaft 38 and provides the motive force and leverage to pivot the shaft 38 (as the handle 48 is pulled or pushed to engage or disengage the abrasive wheel W, respectively).
As seen in FIGS. 6 and 7, the lock or brake system 56 includes a split sleeve 60 that is biased (as by a spring 62) inward onto a shaft 64. One end of the shaft 64 is mounted to the L-arm 44 and the other end is mounted in the split sleeve 60. The sleeve 60 is operably mounted to the saw frame or base 12 as indicated at 66. The lock 56 is configured so that when the sleeve 60 is urged opened, the shaft 64 slides or reciprocates within the sleeve 60 and when the sleeve 60 closes, the shaft 64 is secured in the sleeve 60 and prevented from reciprocating (moving). A trigger or grip 68 on the handle 48 is operably connected to the lock 56 to engage and disengage the lock 56.
Referring to FIGS. 2-5, as seen in the cutting region 14, the drive wheel 36 is mounted to the end of the drive shaft 26. A saw wheel arm 70 is mounted to the end of the pivot shaft 38. A final drive toothed drive wheel 72 is mounted to an opposite end of the saw wheel arm 70 and a wheel drive belt 74 is positioned around the two drive wheels 36, 72 to transfer power from the drive shaft 26 to the final drive wheel 72. The abrasive wheel W (not shown) is mounted to the final drive wheel 72. FIGS. 5A and 5B show the wheel shroud or cover 76 in place on the saw wheel arm 70. A water nozzle 78 is shown on the shroud 76 to provide a water feed to the wheel W during the cutting operation. A water pump and motor (not shown) supply water to the water nozzle 78.
The present saw 10 includes a novel arrangement for providing the proper tension in the wheel drive belt 74. As can be seen in FIGS. 3-4 and 11 (as indicated at 80 in FIG. 4) the drive shaft 26 is eccentrically set within the pivot shaft 38. In this arrangement, the distance d₇₄from the center of the drive shaft C₂₆(the position of the center of the drive shaft 26 remains fixed) to periphery of the pivot shaft P₃₈varies depending upon where the eccentricity lies relative to the center C₂₆of the drive shaft 26. In effect, the eccentrically mounted shafts 26, 38 serve as a cam surface to increase or decrease the distance d₇₄between the center of the drive shaft C₂₆and the center of the final drive wheel C₇₂. This variation or change in distance serves to permit adjusting the tension in the wheel drive belt 74.
The present saw 10 also includes a novel bed 18 and feed system 82 as seen in FIGS. 1 and 8-9. It will be appreciated that the bed 18 is used to support specimens as they are cut. In a typical saw configuration, the bed is fixed and the saw is brought down (pivoted) into the specimen to carry out the cut. In the present saw 10, in an auto-feed mode of operation (discussed in more detail below), the abrasive wheel W is locked in a cutting position, and the feed system 82 moves the bed 18 with the specimen mounted thereto into the wheel W.
The bed 18 is set on a set of bearings 84 to move toward and away from the wheel W, or into and out of the cutting zone. A screw drive 86 provides the motive force to move the bed 18. This is referred to as a Y-drive (the y-direction of feeding into the wheel W). A worm gear (or screw) 88 is mounted to the saw frame 12 and a receiver gearbox 90 is mounted to the bed 18. To permit manual movement or adjustment of the bed 18 position, a hand crank 92 is mounted to the saw base 12 and is operably connected to the worm gear 88. As will be discussed below, the saw 10 includes a motor and drive assembly 94 (wheels/gears 96 and belts 98) for operation in the auto-feed mode.
The saw 10 also includes a transverse or X-drive 100 as seen in FIGS. 9 and 12 that moves the bed 18 (and the specimen) transverse to the direction of cutting (as indicated by the arrow at 102). The X-drive assembly 100 includes a shaft 104 (that extends from the front of the saw 10) having a bevel gear 106 mounted to an end thereof. A second bevel gear 108 transfers power to a worm gear 110 to which a gear box 112 (on the bed 18) is meshed. A hand crank 114 on the front 115 of the saw 10 is used to drive or move the bed 18 in the transverse (X) direction. In this manner, sections of specimens can be serially or sequentially cut from a single sample. This eliminates the need to clamp a sample, cut the specimen, unclamp, move and re-clamp the sample, and cut the next specimen. This can be quite time consuming and labor intensive if a number of specimens are needed. The present X-drive 100 permits carrying out multiple cuts from a single clamping of the sample and also permits better and more precise control of the size of the specimen that is cut.
As seen in FIGS. 1, 5A and 9, the present saw 10 includes one or more wear strips 116 mounted to the saw case 117. The wear strips 116 are mounted in alignment with the cutting (saw) wheel W to prevent debris that is generated and ejected from the wheel W during the cutting operation from impinging on the case or housing 117. The wear strips 116 are replaceable and in this manner the wear strip 116 serves as a sacrificial element to prevent excessive damage to or wear of the case 117. In the present saw 10, the wear strip 116 extends up the rear of the case 117 and along the bottom, where debris impingement would be most severe.
The viewing/protective hood 118 is shown in FIG. 10. The hood 118 includes a front 120 wall having a viewing window 122 and a top wall 124. The front and top walls 120, 124 are hinged 126 to one another. One or more cylinders 128 extend between the hood 118 and the case 117 and are used to assist lifting and lowering, and to dampen movement of the hood 118.
The hood 118 includes guide rollers 130 a,b on the front wall 120 that engage tracks 132 a,b in the front/side of the case 118. One of the rollers 130 a (on the left-hand side) also engages a track 134 along the top of the case 117. The tracks 132 a,b and 134 have a T-slot (not shown) formed in them to capture their respective rollers 130 a,b. The rollers 130 a,b are thus maintained or captured in the front/side tracks 132 to allow the front wall 120 and the top 124 to be rotated up and rearward. A recess 136 in the track 134 is positioned so that the roller guide 130 a can reside in the recess 136 to maintain the hood 118 open for access to the cutting region 14. An interlock system 138 (key 140 and receiver 142) isolates power to the saw 10 when the key 140 is removed from the receiver 142, that is, when the hood 118 is open. A portion 152 of the left side panel is configured to slide forward and rearward (as indicated by the arrow at 154) along with the movement of the hood 118. Roller 130 b, which resides in track 132 b, is, at it reaches the top of the track 132 b, captured in a receiver 156 in the panel portion 152. As the front wall 120 is moved rearward, the roller 130 b, captured in the receiver 156, moves the panel portion 152 rearward to provide increased access to the cutting region 14. When the hood 118 is closed, the roller 130 b (in the receiver 156) moves the panel portion 152 forward to close the panel portion 152.
The saw 10 includes a control system 144 having a touch-pad control panel 22. The control system 144 is microprocessor based and includes a standard (e.g., USB) slot (as at 146) so that new/modified control schemes can be readily installed in the system 144. The touch-pad control panel 22 is configured so that only icons that are needed for any particular mode of operation are displayed. It will be appreciated that any number of different types of control systems 144, panels 22, and the like can be used.
Those skilled in the art will recognize the need to monitor the power that is drawn by the saw 10 (specifically, the wheel motor 24) as one indication of the strain on the motor 24. The present saw 10 includes a powerless or self-powered sensor 148 for monitoring the current drawn by the motor 24. The sensor 148 includes a circuit 150 to convert the current drawn (e.g., 0 to 15 A) to a corresponding voltage (e.g. 0-10V) and provides indication of the current. The current drawn by the wheel drive motor 24 is an indicator of whether the wheel W is being too quickly brought into contact with the specimen.
In auto-feed mode, the feed rate of the specimen is programmed into the controller, 144, as is the length or distance of the cut. In a preferred embodiment, then the sensor 148 senses that the current drawn by the motor 24 is greater than a predetermined level, the table motor 94 is slowed or stopped to prevent damage to the motor 94 or wheel W.
As set forth above, the saw 10 can be operated in manual mode. The specimen is clamped to the bed 18 and the specimen position is adjusted (using the hand cranks to adjust the X and Y directions). Similar to known saws, the wheel W is manually brought down into contact with the specimen by pulling the handle 48 downward. Moving (pivoting) the handle 48 upward disengages the wheel W from the specimen. The hood 118 can then be opened and the specimen removed.
In an auto-feed mode, the specimen is clamped to the bed 18 with the bed in a home position, and the wheel W is pulled downward so that the periphery of the wheel extends below the bed 18 top surface. The lock or brake 56 to maintain the wheel W in this (cutting) position. The saw 10 is set in auto-feed mode by setting the feed rate of the specimen on the control panel 22. The brake 56 prevents the wheel W from “jumping” upward when the specimen contacts the wheel W. The bed 18 then moves from the home position toward the wheel W to feed the specimen into the wheel W. If during cutting the current drawn by the motor 24 is too high, the bed 18 can slow and/or stop (by automatic/controlled operation of the motor and drive assembly 94) to protect the abrasive wheel W and/or motor 24. When the cut is complete, the bed 18 automatically returns to the home position. If the specimen is to be cut serially, the X-drive 100 can be actuated and the specimen repositioned (transversely). The auto-feed sequence can then be reinitiated to perform the next sequential cut.
All patents referred to herein, are hereby incorporated herein by reference, whether or not specifically done so within the text of this disclosure.
In the present disclosure, the words “a” or “an” are to be taken to include both the singular and the plural. Conversely, any reference to plural items shall, where appropriate, include the singular.
From the foregoing it will be observed that numerous modifications and variations can be effectuated without departing from the true spirit and scope of the novel concepts of the present invention. It is to be understood that no limitation with respect to the specific embodiments illustrated is intended or should be inferred. The disclosure is intended to cover all such modifications as fall within the scope of the invention.

Claims

1. An abrasive saw having an associated cutting wheel for cutting objects mounted thereto, comprising:

a base; and

a cutting assembly operably mounted to the base, the cutting assembly including a pivot shaft, a drive shaft operably mounted to the pivot shaft, a drive, and a drive wheel, the drive being operably connected to the drive shaft, the drive shaft being operably connected to the drive wheel by a flexible drive element to rotate the drive wheel, the drive wheel having the associated cutting wheel mounted thereto, the pivot shaft being pivotable to move the associated cutting wheel between a cutting position and a disengaged position,

wherein the drive shaft has an axis of rotation and the drive wheel has an axis of rotation spaced a distance from the drive shaft axis of rotation, and wherein the flexible drive element spans the distance between the drive wheel axis of rotation and the drive shaft axis of rotation, and wherein the distance between the drive wheel axis of rotation and the drive shaft axis of rotation is variable to increase or decrease a tension in the flexible drive element.

2. The abrasive saw in accordance with claim 1 wherein the drive shaft is disposed within the pivot shaft and wherein rotation of the pivot shaft varies the distance between the drive wheel axis of rotation and the drive shaft axis of rotation.

3. The abrasive saw in accordance with claim 2 wherein the pivot shaft has a longitudinal axis and wherein a distance between the pivot shaft longitudinal axis and the drive wheel axis of rotation is fixed.

4. The abrasive saw in accordance with claim 3 wherein the drive shaft is eccentrically disposed within the pivot shaft.

5. The abrasive saw in accordance with claim 1 wherein the flexible drive element is a drive belt, and wherein varying the distance between the drive wheel axis of rotation and the drive shaft axis of rotation varies the tension in the belt.

6. The abrasive saw in accordance with claim 5 wherein the drive belt is a toothed belt and wherein a toothed wheel is mounted to the drive shaft and the drive wheel is a toothed wheel.

7. An abrasive saw having an associated cutting wheel for cutting objects mounted thereto, comprising:

a base;

a cutting assembly operably mounted to the base, the cutting assembly including a pivot shaft, a drive shaft operably mounted to the pivot shaft, a drive, and a drive wheel, the drive being operably connected to the drive shaft and the drive wheel to rotate the drive wheel, the drive wheel having the associated cutting wheel mounted thereto, the pivot shaft being pivotable to move the associated cutting wheel between a cutting position and a disengaged position, the cutting assembly including a lock to lock the associated cutting wheel in the cutting position;

a feed table operably mounted to the base, the feed table movable forward and rearward in a direction of rotation of the associated cutting wheel; and

a controller,

wherein the associated cutting wheel is lockable in the cutting position and the feed table, with the object secured thereto, is moved toward the associated cutting wheel to cut the object.

8. The abrasive saw in accordance with claim 7 including a drive for moving the feed table.

9. The abrasive saw in accordance with claim 8 wherein the drive is a manually operated drive.

10. The abrasive saw in accordance with claim 8 wherein the drive is a motor.

11. The abrasive saw in accordance with claim 10 wherein the controller controls the drive to move the table toward the associated cutting wheel.

12. The abrasive saw in accordance with claim 11 including a current sensor circuit, and wherein the current sensor circuit generates a signal to the controller and, upon sensing a predetermined current, the controller slows and/or stops the drive to slow and/or stop movement of the table toward the associated cutting wheel.

13. The abrasive saw in accordance with claim 11 wherein the controller includes an input for inputting the speed of the table moving toward the associated cutting wheel.

14. The abrasive saw in accordance with claim 7 including a transverse drive to move the feed table transverse to the direction of rotation of the associated cutting wheel.

15. An abrasive saw having an associated cutting wheel for cutting objects mounted thereto, comprising:

a base;

a cutting assembly operably mounted to the base, the cutting assembly configured to move the associated cutting wheel between a cutting position and a disengaged position, the cutting assembly including a lock to lock the associated cutting wheel in the cutting position;

an enclosure enclosing the cutting assembly, the enclosure having at least one stationary side and an openable front panel and top panel, the front panel and the top panel being hingedly mounted to one another to open as a unitary assembly, the assembly openable to provide access to the cutting assembly.

16. The abrasive saw in accordance with claim 15 including at least one wear element disposed on the enclosure aligned with the direction of rotation of the associated cutting wheel.

17. The abrasive saw in accordance with claim 15 including a controller and at least one interlock, wherein when the interlock is open, the controller prevents operation of the abrasive saw.

18. The abrasive saw in accordance with claim 17 wherein the at least one interlock is located on the enclosure.

19. The abrasive saw in accordance with claim 15 including a fluid feed to feed fluid to a shroud covering the associated cutting wheel.

20. The abrasive saw in accordance with claim 15 wherein a portion of a side panel is operably connected to the front panel and the top panel to open therewith as a unitary assembly.