WO2018203134A1

WO2018203134A1 - Spark suppressor for rotary abrasive tool

Info

Publication number: WO2018203134A1
Application number: PCT/IB2018/000564
Authority: WO
Inventors: Brian KEISER; Manfred Naumann; Ralf Blechschmidt; Sebastian Schuster; Shane L. CLIFFORD; Harald RUB
Original assignee: Dronco Gmbh
Priority date: 2017-05-01
Filing date: 2018-05-01
Publication date: 2018-11-08
Also published as: WO2018203134A8

Abstract

A spark suppressor and spark- suppressing rotary abrasive tool having at least one non- smooth spark energy dissipating surface or layer disposed adjacent a spark generating region where there is abrasive contact between a workpiece and rotating abrasive implement of the tool. A preferred spark suppressor is a spark suppressing protective guard for the tool having a spark energy dissipating surface or layer within disposed adjacent to and facing toward the spark generating region. A preferred spark-suppressing rotary abrasive tool is equipped with such a spark-suppressing guard. A preferred spark energy dissipating surface is of three-dimensionally contoured construction having at least a plurality of upraised portions against which sparks generated contact dissipating their momentum and velocity until stopped and retained within the spark suppressor. A preferred spark energy dissipating layer is formed of a plurality of wires or pins that can be entangled to form a porous non-woven spark catching layer.

Description

SPARK SUPPRESSOR FOR ROTARY ABRASIVE TOOL

CROSS REFERENCE

[0001] Pursuant to 35 U.S.C. § 119(e), this application claims all benefits to and priority in U.S. Provisional Application Serial No. 62/492,409, filed on May 1, 2017, the entirety of which is hereby expressly incorporated by reference here.

FIELD

[0002] The present invention is directed to a spark suppressing device for power tools used in grinding and cutting applications, more particularly to a spark suppressor for grinding power tools, including rotary abrasive tools equipped with grinding or cutting wheels or discs, which catches, traps and/or otherwise suppresses sparks generated during grinding or cutting.

BACKGROUND

[0003] Sparks are commonly generated in relatively large numbers during use of rotary power tools equipped with grinding or cutting wheels or discs during contact between the rotating wheel or disc and the surface or material of a workpiece being ground or cut. Even though these rotary power tools typically are equipped with a safety shield, guard or shroud that extends around at least part of the cutting wheel or disc to shield the operator from the sparks, at least some of the sparks generated are nonetheless discharged from the rotating wheel or disc outwardly beyond the shield, guard or shroud where they can still make contact with the operator, come in contact with combustible or flammable material, or otherwise produce an unsafe or less than desirable situation.

[0004] Depending upon the material of the workpiece being ground or cut, the type of grinding or cutting wheel or disc, as well as the speed at which the wheel or disc is rotated, it is not uncommon for at least a plurality of pairs, i.e. at least three, of sparks per second to be generated at an interface of abrasive contact, e.g., spark generating region, between the rotating wheel or disc and the surface of the material being ground or cut. As the sparks are rapidly generated, they are expelled from the abrasive contact interface of the workpiece in a direction generally tangential to the outer periphery of the wheel or desk where the shield, guard or shroud essentially serves as a guide to funnel them and concentrate them into a steady stream of sparks that are discharged from one end thereof. When discharged, the sparks that make up such a spark stream tend to spray in different directions at relatively high velocities where they can impact against the operator, land on combustible services causing them to smolder or even ignite, ignite flammable material, and generally cause undesired damage and problems.

[0005] Not only can sparks impacting against an operator because physical harm or damage to the operator, such as by causing eye damage, skin burns, and other irritation or harm, but the presence of such randomly flying sparks generated during cutting or grinding necessitate the operator wearing a considerable amount of relatively heavy and cumbersome safety equipment that typically includes goggles, gloves, safety headwear, and rugged or tough protective clothing. While such safety equipment definitely can help protect an operator from sparks generated during cutting or grinding, some sparks can and do pass through or between such safety equipment coming into contact with the operator causing periodic harm or injuries. In addition, the use of such safety equipment tends to restrict operator motion while at times limiting their vision all while increasing the body temperature of the operator as a result of the equipment being heavy, thick and bulky where cutting or grinding operating conditions are already hot.

[0006] There are certain applications where sparks are especially undesirable, particularly where the grinding or cutting is done in an environment where highly combustible materials, liquids or gases are present necessitating the need to take great precautions during such cutting or grinding to minimize combustion or ignition from occurring. One such known application is in fire and rescue where firemen, safety and other types of rescue personnel use special dedicated cutters to cut the metal and other material in vehicles, buildings, and other things when required to cut through to reach people that are injured or trapped. During use in such fire and rescue

applications, preventing sparks is especially important because many times the cutting is being done in the presence of flammable liquids like diesel fuel, gasoline, kerosene and the like.

[0007] While attempts have been made to make cutting and grinding wheels or discs of a material or construction that minimizes the amount, rate and/or density of sparks generated at the abrasive contact interface between the wheel or disc and the surface or workpiece being cut or ground, efforts heretofore have met with little or no commercial success. It has typically been found that the greater the spark suppression achieved, the poorer cutting or grinding performance that results.

[0008] What is needed is a spark suppressing device for such a rotary power tool equipped with such a cutting or grinding wheel or disc that reduces the number of sparks expelled free of the shield, guard or shroud of the tool during cutting or grinding operation. SUMMARY

[0009] The present invention is directed to a spark suppressing device for rotary power tools used in grinding and cutting applications that is constructed and arranged to reduce and preferably minimize the number of sparks generated during grinding and cutting that are discharged free of the power tool. Such a spark suppressing device of the present invention is a spark suppressor having a spark energy or spark momentum absorbing surface or layer of non- smooth construction and which preferably is three-dimensionally contoured so as to contact, impact, catch or otherwise slow the momentum and speed of sparks generated during grinding or cutting until the sparks velocity drops to zero retaining trapping such non-moving sparks within the spark suppressor.

[0010] A preferred spark suppressor is in the form of a guard, shield or shroud attachable to a rotary abrasive power tool, such as an angle grinder, within which has at least one and preferably at least a plurality of such non- smooth surfaces or layers of spark catching construction, In one preferred embodiment, one or more such surfaces has upraised projections, which can be in the form of spikes against which sparks impact during spark suppressor operation. In one such preferred embodiment, the spikes are in the firm of a plurality of pairs of outwardly extending elongate wires or pins which can have differing lengths and can be arranged to form a non- woven entangled spark suppressing layer of porous construction with sparks entering such pores becoming trapped within.

DRAWING DESCRIPTION

[0011] One or more preferred exemplary embodiments of the invention are illustrated in the accompanying drawings in which like reference numerals represent like parts throughout and in which:

[0012] Figure 1 is a top front perspective view of a grinding or cutting machine that can be retrofitted or equipped with a spark suppressing arrangement constructed in accordance with the present invention;

[0013] Figure 2 is a bottom left hand side perspective view of the grinding or cutting machine of Figure 1;

[0014] Figure 3 is an interior perspective view of the guard removed from the grinder; [0015] Figure 4 is a perspective view of a grinding or cutting machine not equipped with any spark suppressing arrangement illustrating unsuppressed flow of sparks generated during grinding or cutting of a workpiece using the grinding or cutting machine;

[0016] Figure 5 is a schematic depiction of a guard of a grinding or cutting machine not equipped with any spark suppressing arrangement;

[0017] Figure 6 is a schematic depiction of a guard of a grinding or cutting machine constructed with a spark suppressing arrangement of the present invention;

[0018] Figure 7 is a perspective view of a preferred embodiment of a spark suppression equipped grinder or cutting machine guard;

[0019] Figure 8 is a top front perspective view of the spark suppression equipped grinder or cutting machine guard of Figure 7;

[0020] Figure 9 is a perspective view of a grinding or cutting machine equipped with a spark suppressing arrangement illustrating a suppressed lesser flow of sparks generated during grinding or cutting of a workpiece using the grinding or cutting machine;

[0021] Figure 10 is a chart illustrating various kinds and types of protective abrasive tools and/or tool guards with which a spark suppressor constructed in accordance with the present invention is compatible;

[0022] Figure 11 is a bottom perspective view of a second preferred embodiment of a spark arrestor in accordance with the invention attached to a cutting or grinding machine with the spark arrestor equipped with a 2-piece spark suppressing guard of the present invention that encompasses or encircles at least half of the rotary cutting or grinding implement and preferably encompasses or encircles about two-thirds of the rotary cutting or grinding implement;

[0023] Figures 12 and 13 are front elevation views of the second embodiment of the spark arrestor of Figure 11 depicting a cutter access opening formed in the pair of halves that form the 2-piece spark suppressing guard that provides access to a rotary cutting or grinding implement of the cutting or grinding machine to which the spark arrestor is removably attached;

[0024] Figure 14 illustrates a top plan view of a larger semicircular shaped one of the halves of the 2-piece spark suppressing guard of the second spark arrestor equipped with a removable mounting arrangement for removably mounting the spark arrestor to a rotary cutting or grinding machine that covers at least 135°, preferably covering at least 150°, and more preferably covering at least about 180° of the periphery and disc platter surfaces of a circular grinding or cutting implement of the grinding or cutting machine to which the guard is removably mounted;

[0025] Figure 15 is a rear elevation view of the larger semicircular spark suppressing guard half of Figure 14 illustrating a spark catching interior with its interior surface comprised of upwardly extending momentum absorbing spark impacting/catching spike, barbs, hooks or wires distributed substantially uniformly along substantially the entire of the interior guard half surface;

[0026] Figure 16 illustrates a top plan view of a smaller quarter-circle shaped one of the halves of the 2-piece spark suppressing guard of the second spark arrestor that covers at least 30°, preferably covers at least 37.5°, and more preferably covers at least about 45° of the periphery and disc platter surfaces of the circular grinding or cutting implement of the grinding or cutting machine to which the guard is mounted; and

[0027] Figure 17 is a rear elevation view of the smaller quarter-circle shaped spark suppressing guard half of Figure 14 illustrating a spark catching interior with its interior surface also comprised of upwardly extending momentum absorbing spark impacting/catching spike, barbs, hooks or wires distributed substantially uniformly along substantially the entire of the interior guard half surface.

[0028] Before explaining one or more embodiments of the invention in detail, it is to be understood that the invention is not limited in its application to the details of construction and the arrangement of the components set forth in the following description or illustrated in any appended drawings. The invention is capable of other embodiments, which can be practiced or carried out in various ways. Also, it is to be understood that the phraseology and terminology employed herein is for the purpose of description and should not be regarded as limiting.

DESCRIPTION OF INVENTION

[0029] As discussed in more detail below, the present invention is directed to a spark suppressor 65 for suppressing sparks 88, as well as a method of suppressing sparks 88 generated during operation of a rotary abrasive tool 20, such as a grinder 46 or a fire/rescue safety saw equipped with an abrasive implement 30, such as in the form of a rotary grinding disc or cutting wheel 50, in order to reduce, preferably minimize, and more preferably substantially completely prevent sparks 88 formed during abrasive contact between a workpiece 90 and the abrasive implement 30 from being discharged out an operator protecting safety guard 32, e.g., protective shroud, of the tool 20. In a preferred embodiment, a spark suppressor 65 constructed in accordance with the present invention can be in the form of a spark- suppressing operator protective guard 32' configured with one or more three-dimensionally contoured internal kinetic spark energy absorbing surfaces 108 and/or 120 that relatively rapidly absorbs or bleeds off enough kinetic energy of sparks 88 generated at and ejected at relatively high velocities from a region of abrasive implement- workpiece contact for at least some of the sparks 88 to be caught or trapped thereby or therein. In another preferred embodiment, one or more kinetic spark energy absorbers 110 are employed such as by being attached, mounted, affixed, applied or disposed on or to and/or integrally formed with or embedded into one or more portions of protective guard 32 against which ejected sparks 88 contact during workpiece material removal with abrasive tool 20. A spark suppression equipped grinder and/or spark suppressing grinder of the present invention has such a spark suppressor 65 constructed in accordance with the invention that minimizes the amount of dust, chips and other debris generated during abrasive grinding or cutting of a workpiece by the spark suppressor or spark suppressing arrangement catching, trapping or otherwise collecting at least some dust, chips, and other debris while the spark suppressor or spark suppressing arrangement also is catching, trapping, or otherwise collecting sparks

[0030] Figures 1-4 illustrate an exemplary rotary abrasive tool 20 equipped with a drive 22, whose housing 24 can define an elongate graspable handle 26, coupled to a gearbox 28 which rotatively drives an annular, circular or generally disc-shaped abrasive implement 30 at least partially enshrouded by or within a protective guard 32 removably attached to part of a casing 34 of the gearbox 28 whose function is to shield an operator from debris, chips and sparks ejected from the rotating abrasive implement 30 contacting a workpiece 90 (Figure 4) being abraded thereby. If desired, the tool 20 can also be equipped with an auxiliary handle 25 (Figure 2), such as where it is desired or required for an operator 96 (Figure 4) of the tool 20 to operate the tool 20 while grasping at least one and preferably both handles 25 and 26 of the tool 20

simultaneously with both hands 98 and 99 (Figure 4). A power source 36 is operatively coupled or connected to the abrasive tool drive 22 that pneumatically or electrically powers the drive 22 during abrasive tool operation to rotate the abrasive implement 30 at rotational speeds ranging from as little as 100-200 revolutions per minute (RPM) to as fast as 80,000-90,000 RPM. In the preferred rotary abrasive tool 20 depicted in Figures 1 and 2, an electrical power source 36 powers the drive 22, e.g., electric drive motor, with electrical current of the power source 36 supplied via an electrical power cord 38 to the drive 22.

[0031] While the protective guard 32 can be mounted to the gearbox casing 34 using a multitude of different guard mounting arrangements, the guard 32 of the tool 20 is shown in Figure 1 removably anchored to part of the casing 34 using a releasable tool-less guard mount 40 which employs a latch 42 manipulated by a user of the tool 20 to tighten a circular guard mounting clamp 44 around part of the casing 34 to fix it thereto to use the tool 20, and to loosen the clamp 44 when it is desired to attach or replace the abrasive implement 30. When the clamp 44 is tightened, the clamp 44 fixes the guard 32 to the casing 34 thereby also fixing the position of the guard 32 relative to the abrasive implement 30 such that the guard 32 covers or enshrouds at least part of an annular or radial extent of the abrasive implement 30 in the manner depicted in Figure 1.

[0032] The tool 20 can be a conventional rotary cutter or grinder 46, such as the angle grinder 48 illustrated in Figures 1 and 2, and the abrasive implement 30 can be a conventional grinding disc or cutting wheel 50, such as the disc or wheel 50 also illustrated in Figures 1 and 2. Such an abrasive grinding disc or cutting wheel 50 is formed of an annular, circular or disc-shaped body 52 having a pair of oppositely outwardly facing sides or exterior surfaces 54, 56 and has a radially outwardly disposed abrasive grinding or cutting region 62 extending radially and circumferentially at or along, e.g., adjacent, an outer peripheral edge 58 of the disc or wheel 50 that also defines an outer circumference 60 of the disc or wheel 50. With specific reference to Figure 2, disc or wheel 50 is removably attached to a spindle (not shown) of the gearbox 28 by a clamping nut 45 with the spindle and/or nut 45 extending through an opening in a center 47 of the disc or wheel 50 that also defines an axis of rotation 49 about which the disc or wheel 50 rotates during abrasive tool, e.g., grinder, operation. The disc or wheel 50 can be any type of an abrasive disc or wheel, including an abrasive grinding disc or cutting wheel, e.g., cut-off wheel, of resinous, metal, metallic, and/or composite construction that preferably is further composed of, formed with or of, or otherwise includes one or more types of abrasives, such as abrasive particles formed of one or more of diamond(s), cubic boron nitride, ceramic aluminum oxide, and/or zirconia aluminum oxide. [0033] The protective guard 32 has an arcuate preferably generally semicircular sidewall 64 extending radially outwardly from the gearbox casing 34 at or adjacent the guard mounting clamp 44 between the casing 34 and the disc or wheel 50 providing a radially extending protective inner spark-deflector shield 66 disposed between an operator 96 of the grinder 46 and the disc or wheel 50 during grinder operation. The guard 32 also has a flange or endwall 68 about the curved periphery of the guard sidewall 64 that extends generally transversely or perpendicular to the guard sidewall 64 providing a curved axially oriented radial spark-deflector shield 70 spaced radially outwardly from the outer peripheral edge 58 of the disc or wheel 50 that is disposed between the outer peripheral disc or wheel edge 58 and the operator 96 during grinder operation.

[0034] The guard 32 can be a cutting guard 35 like that best shown in Figure 2, such is commonly used with a rotary cutting tool, e.g., grinder 46, equipped with a rotary abrasive cutting implement 30, such as a disc or wheel 50 that is a cutting wheel 55, e.g., cut-off wheel (Figure 2), which is used or otherwise configured for cutting metal, concrete, tile, other ceramic materials, or the like. With continued reference to Figure 2, where the guard 32 is a cutting guard 35, it is further equipped with a second or outer sidewall 72 of generally semicircular shape that extends along and overlies part of the opposite side or exterior surface 56 of the disc or wheel 50. Where the guard 32 is a cutting guard 35 equipped with such a second or outer guard sidewall 72, the outer sidewall 72 can and preferably does extend generally transversely from the guard endwall 68 radially inwardly toward the center 47 or axis of rotation 49 of the disc or wheel 50 with the outer guard sidewall 72 providing or defining an outer spark-deflector shield 74 that is generally parallel with the inner spark-deflector shield 66 provided or defined by inner guard sidewall 64. Where a grinder 46 is equipped with a guard 32 of such dual-walled construction, such a dual- walled cutting guard 35 can and preferably does enshroud at least about one-third and no greater than about two-thirds, preferably between about one-third and about one-half, of the circumferential extent of the disc or wheel 50, e.g., cutting wheel 55, with its inner guard sidewall 64 disposed on one outer side or exterior surface 54 of the disc or wheel 50, and its outer guard sidewall 72 disposed on the other side or exterior surface 56 of the disc or wheel 50.

[0035] A preferred but exemplary guard 32 is shown in more detail in Figure 3 removed from the grinder 46, with any outer sidewall 72 that the guard 32 might have been formed with removed from the rest of the guard 32 for clarity to more clearly depict an interiorly-disposed spark-guiding chute 75 formed collectively by either the guard endwall 68 and the sidewall 64, or by the guard endwall 68 and both guard sidewalls 64 and 72. Figure 3 illustrates a guard 32 of such construction that is not equipped with any spark suppressor so that the below more detailed description of the novel construction, inventive operation, advantageous uses, and unique benefits of a spark suppressor constructed in accordance with the present invention will be better understood.

[0036] With continued reference to Figure 3, the inner guard sidewall 64 is formed with a centrally disposed guard-mounting hub 76 which has a generally centrally located guard-seating bore 78 formed therein that is generally coaxial with the disc or wheel axis of rotation 49, e.g., coaxial with the spindle axis of rotation. The guard-mounting hub 76 can and preferably does include a releasable mounting collar 80 formed or carrying the guard mounting clamp 44 and which is configured to telescopically slidably receive or register with a generally cylindrical outwardly extending mounting hub or recessed mounting seat (not shown) of the portion of the gearbox casing 34 (not shown in Figure 3) through which the spindle (not shown) extends.

[0037] Figure 3 further illustrates that the protective guard 32 has generally circular inner platter 77 which can be at least partially formed of or from the guard-mounting hub 76 and which encompasses or encircles the guard-seating bore 78. The inner guard sidewall 64 is formed of a pie-shaped segment or wedge 82 that extends radially outwardly from the platter 77 and which can include part or substantially all the platter 77. The inner spark-deflector shield 66 of the inner guard sidewall 64 has a substantially smooth spark-deflecting interior surface 84 of imperforate, solid and/or hard construction which overlies, faces toward, extends generally parallel to, and is disposed along the one side or exterior surface 54 of the disc or wheel 50 when the guard 32 is mounted on grinder 46 and disc or wheel 50 coupled to its spindle. As also shown in Figure 3, the radial spark-deflector shield 70 of the guard endwall 68 has a substantially smooth spark- deflecting interior surface 86 of imperforate, solid and/or hard construction which faces toward but is spaced radially outwardly of the outer peripheral edge 58 of the disc or wheel 50. Where the protective guard 32 is a cutting guard 35 equipped with an outer guard sidewall 72 (not shown in Figure 3) that also defines an outer spark-deflector shield 74, the outer guard sidewall 72 and outer spark-deflector shield 74 has a substantially smooth spark-deflecting interior surface 85 (Figure 2) which overlies, faces toward, extends generally parallel to, and is disposed along the outer side or exterior surface 56 of the disc or wheel 50 when the guard 32 is mounted on grinder 46 and disc or wheel 50 coupled to its spindle.

[0038] . During grinder operation, sparks 88 propelled generally axially away from the disc or wheel 50 toward the inner spark-deflector shield 66 slidably impact against spark-deflecting interior guard surface 84 deflecting the sparks 88 away from the disc or wheel 50 preferably also in a direction away from the operator 96. During operation, sparks 88 propelled generally radially outwardly away from the outer peripheral edge 58 of the disc or wheel 50 toward the radial spark-deflector shield 70 slidably impact against spark-deflecting interior guard surface 86 also deflecting the sparks 88 away from and circumferentially along the outer peripheral edge 58 of the disc or wheel 50 preferably also in a direction away from the operator 96. During operation, the sparks 88 deflected by these spark-energy deflecting surfaces 84 and/or 86 are guided along the spark-guiding chute 75 formed thereby and by spark-deflector shields 66 and 70 in the direction of rotation of the disc or wheel 50 until they exit from a discharge 79 of the chute 75 and guard 32.

[0039] During operation of a grinder 46 equipped with a protective guard 32 that is a cutting guard 35 that has an outer spark-deflector shield 74, sparks 88 propelled generally axially away from the disc or wheel 50 toward the outer spark-deflector shield 74 slidably impact against spark-deflecting interior guard surface 85 deflecting the sparks 88 away from the disc or wheel 50 preferably also in a direction generally away from the operator 96. During operation, the sparks 88 deflected by these spark-deflecting surfaces 84, 85 and/or 86 are guided along the spark-guiding chute 75 formed thereby and by spark-deflector shields 66, 70 and 74 in the direction of rotation of the disc or wheel 50 until they exit from the discharge 79 (Figure 2) of the chute 75 and guard 32.

[0040] With additional reference to Figures 4 and 5, an abrasive grinding or cutting region 62 where the abrasive implement 30, e.g., disc or wheel 50, contacts the workpiece 90 also at least in part defines a spark generating region 95 disposed at or adjacent, e.g., slightly downstream, of the grinding or cutting region 62 from which sparks 88 are propelled radially and/or axially outwardly from workpiece 90 into the spark-guiding chute 75 of the guard 32. During operation, sparks 88 generated by or from the workpiece 90, abrasives of the disc or wheel 50, and/or material, e.g., resinous material, from which the disc or wheel 50 is formed are propelled radially and axially outwardly away from regions 62 and/or 95 at relatively high velocities. The rapidly moving sparks 88 impact against one or more spark-deflecting surface 84, 85 and/or 86 within the chute 75 directing the sparks 88 within the guard 32 along the chute 75 radially outwardly along or about the periphery of the disc or wheel 50 slidably deflecting the sparks 88 along the chute 75 in the direction of disc or wheel rotation with most of the sparks 88 exiting the guard 32 in a discharge stream 94 of sparks 88.

[0041] As best shown in Figure 4, the protective guard 32 is oriented relative to an operator 96 operating the tool 20, e.g., grinder 46, so that the discharge stream 94 of sparks 88 typically is ejected from the guard 32 away from the operator 96 and preferably also away from any hand(s) 98 of the operator 96 gripping the tool 20. As is also shown in Figure 4, depending on factors such as, the hardness and material of construction of the workpiece 90, the makeup and abrasive composition of the disc or wheel 50, the rotational speed, feed rate and force applied urging the disc or wheel 50 against the workpiece 90, the amount, magnitude or volume of sparks 88 generated can be so great that one or more misdirected secondary spark streams 100 and/or 102 can be produced and/or ejected outwardly of the guard 32 in one or more undesirable directions other than or in addition to the primary or discharge stream 94. Where one or more such secondary spark streams 100 and/or 102 they typically are undesirable because they can contact the operator 96 and/or can be directed in one or more directions the operator 96 does not desire sparks 88 to travel.

[0042] While such an un- suppressed grinder guard construction has been acceptable in the past, a need has arisen to reduce and preferably minimize transmission or conveyance of sparks formed by contact between the rotating disc or wheel 50 and the workpiece 90, and/or of or from chips formed by or during contact between the rotating disc or wheel 50 and the workpiece 90. Doing so can in turn reduce the risk of ignition of combustible gases, vapors and/or materials that could combust upon comping into contact with such sparks propelled from the workpiece- engaging rotating disc or wheel 50 during grinding or cutting of the workpiece 90.

[0043] Figure 6 diagrammatically depicts a preferred but exemplary embodiment of a spark suppressor 65 constructed in accordance with the present invention that preferably is a suppressing operator-protecting guard 32' for releasable attachment to a rotary abrasive tool 20 formed with or of non-smooth spark kinetic energy dissipating inner surface 108 of the guard 32' that can be and preferably is a rough or roughened spark-slowing surface 109 (Figure 8) and which preferably is three-dimensionally contoured such that the interior spark kinetic energy dissipating surface 108 of the guard 32' can be formed of or include at least a plurality of pairs of, i.e., at least three, upraised spark energy-absorbing projections 110 spaced apart about or along the spark kinetic energy dissipating surface 108. At least the interior spark-deflecting surface 85 of the guard endwall 68 carries or is formed with such a non-smooth, rough or roughened, and/or three-dimensionally contoured spark kinetic energy dissipating surface 108 preferably extending along at least half and more preferably extending along substantially the entire length of the guard endwall 68. Although Figure 6 only depicts such a spark kinetic energy dissipating surface 108 being formed of or on the interior spark-deflecting surface 85 of the guard endwall 68, spark-deflecting interior surfaces 84 and/or 86 of one or both respective inner and outer guard sidewalls 64 and/or 72 can also be carry or be formed with such a non-smooth, rough or roughened, and/or three-dimensionally contoured inner spark kinetic energy dissipating surface 108 that can and preferably also is formed of, with or includes at least a plurality of pairs of upraised and spaced apart spark energy-absorbing projections 110. Where the inner spark kinetic energy dissipating surface 108 extends substantially the length of guard endwall 68, inner guard sidewall 64 and/or outer guard sidewall 72, each spark kinetic energy dissipating surface 108 preferably extends from at or adjacent an intake 81 of the spark-guiding chute 75 of the guard 32' where a stream 105 of sparks 88 enter the chute 75 all the way to or adjacent a discharge 79 of the chute 75 where any remaining sparks 88 exit the guard 32'. Where there are still enough sparks 88 present that make it all the way through the guard 32' to the chute discharge 79 to form a spark stream, sparks 88 exiting out the chute discharge 79 can exit in a discharge stream 94.

[0044] With continued reference to Figure 6, each one of the spark energy-absorbing projections 110 can be and preferably is formed of an elongate upwardly or outwardly extending spike 112 with each spike 112 having a length of at two millimeters, preferably at least five millimeters, and more preferably at least one centimeter forming a bed 114 of the spikes 112 that extends along substantially the entire area of each spark kinetic energy dissipating surface 108 of guard 32'. In a preferred embodiment, a bed 114 of such spikes 112 having one or more such spike lengths preferably have at least a plurality, preferably at least a plurality of pairs of, i.e., at least three, spikes 112 per square inch of area of the bed 114 and/or surface 108. In another preferred embodiment, a bed 114 of such spikes 112 having one or more such spike lengths preferably have at least a plurality, preferably at least a plurality of pairs of, i.e., at least three, spikes 112 per square millimeter of area of the bed 114 and/or surface 108. In still another preferred embodiment, a bed 114 of such spikes 112 having one or more such spike lengths preferably have at least a plurality, preferably at least a plurality of pairs of, i.e., at least three, spikes 112 per square centimeter of area of the bed 114 and/or surface 108.

[0045] Each one of the elongate upwardly or outwardly extending spikes 112 is of resilient and generally stiff or rigid construction with each elongate spike 112 being spring biased being substantially stiff or rigid but possessing at least some flexure to not only better withstand impacts with sparks 88 during spark suppressing operation, but which also facilitates dissipation of kinetic spark energy during such impacts. Although not shown, one or more of the spikes 112 can be formed with a bend or angle such that one or more or all the spikes 112 of bed 114 can have a bent or angled tip, be generally L-shaped or V-shaped with the angled portions generally oriented in one or more desired direction relative to surface 85, surface 108 or the spark stream 105.

[0046] Such a bed 114 of spark impact energy-absorbing spikes 112 can be formed integrally of the endwall 68 of the spark suppressing protective guard 32' or can be removably attached thereto such as by being adhesively attached to the spark-deflecting inner surface 85 of the guard 32'. In a preferred embodiment, such a bed 114 of spark impact energy- absorbing spikes 112 can be of disposable construction such that when the spikes 112 are saturated with sparks trapped or caught by the spikes 112 during use and operation of guard 32' . The spikes 112 of bed 114 can extend upwardly or outwardly from a base 111 (Figure 8), such as a base layer 113, which can be flexible and which helps securely anchor the spikes 112 in place when fixed to the interior spark- deflecting surface 85 of endwall 68 of guard 32' .

[0047] With continued reference to Figure 8, the base 111, preferably outer base layer 113, has an outer surface which can also be porous having at least a plurality of pairs, i.e., at least three, of pores 115 formed in the outer surface of the base layer 113, with such pores 115 preferably also helping to provide spark suppression. Where equipped with such pores 115, pores 115 provide recesses or pockets formed in the outer surface of the outer base layer 113 that receive and hold sparks whose energy or momentum has completely dissipated stopping spark movement and falling into pore(s) 115. In another preferred embodiment, the region of the base layer 113 surrounding each pore 115 is upraised providing a three-dimensionally contoured surface of the base layer 113 against which sparks contact thereby helping to slow spark momentum and velocity dissipating spark kinetic energy. In a preferred embodiment, at least the outer base layer 113 of such a three-dimensionally contoured spark energy dissipating base 111 is made of a non- woven material of porous construction thereby providing pockets and voids within the base 111 that helps hold particulate spark material from caught, trapped, or suppressed sparks suppressed during operation.

[0048] If desired, one of both of the spark deflecting surfaces 84 and/or 86, can be configured like spark deflecting surface 84' shown in Figure 8 with a three dimensionally contoured spark energy dissipating outer surface region 117 that can be formed of at least a plurality of pairs of pores 119 upraised about each pore opening to slow spark velocity during contact therewith. In addition, the presence of the pores 119 preferably also reduces and preferably minimizes the effects of any boundary layer within helping to ensure traveling sparks contact the spark energy dissipating outer surface region 117.

[0049] Spikes 112 are formed of a high temperature material, such as a metal, metallic material, composite material, fibrous material, carbon or carbon fiber material, glass or glass fiber material, or the like, which can withstand a temperature of at least 250 degrees Fahrenheit, and preferably at least 500 degrees Fahrenheit. Such a base or base layer preferably is formed or otherwise composed of a high temperature material, such as a metal, metallic material, composite material, fibrous material, carbon or carbon fiber material, glass or glass fiber material capable of withstanding a temperature of at least 250 degrees Fahrenheit, preferably at least 500 degrees Fahrenheit. In one preferred base or base layer, the base or base layer is formed of a flexible metal or metallic fabric, which can be of woven construction, which preferably is a metallic mesh, preferably metallic micromesh material, made of steel, aluminum, or another metal or metallic material. In another preferred base or base layer, the base or base layer is formed of a flexible metal or metallic mesh material that preferably is a micromesh made of aluminum or a steel, preferably stainless steel, arranged in one or more of the following micromesh patterns or arrangements:.055 inches x .105 inches, .070 inches x .150 inches, and/or .145 inches x .295 inches, .005 inches x .118 inches short way of diamond, e.g., ranging from .005 inches to .118 inches, from .029 inches to .236 inches, and/or from .005 inches to .079 inches, .039 inches x .236 inches long way of diamond, .005 inches x .079 inches strand width micromesh.

[0050] In a preferred embodiment, the spikes 112 are made of a metal, such as steel, which can be a tempered steel, alloyed steel, a coated steel, or the like, with the spikes 112 extending upwardly from a base or base layer that is formed of metal, preferably a metallic mesh material, which cooperate with one another to dissipate heat buildup during spark catching operation thereby advantageously helping to prevent ignition of potential combustible materials nearby the spark suppressor 65 and rotary abrasive tool 20. In a preferred embodiment, spark- suppressing guard 32' also is made of metal, such as a steel, cast iron, or the like, which also helps dissipate the heat of or from sparks caught by the spikes 112 and/or contacting the metal or metallic base or base layer attached to the guard 32' inside the guard 32' by functioning as a heat sink. In such a preferred embodiment, this combination advantageously helps prevent hot spots within the guard 32' from arising by relatively rapidly transferring heat of or from sparks caught within the guard 32' by the spikes 112 and/or base or base layer to the metal guard 32'.

[0051] Although not shown, a spark suppressor regenerator in the form of a toothed or spiked comb, toothed or bristled brush or other toothed, bristled or spike-cleaning component carrying implement or tool can be configured to comb, brush, clean and/or otherwise regenerate the three- dimensionally contoured spark suppressing region of such a spark suppressor 65 preferably by removing at least some of the residual fragments of sparks previously caught, trapped or otherwise suppressed thereby or therein. In a method of regenerating spark suppressing using such spark suppressor regenerator, the bed 114 of upraised spikes 112 of such a spike-equipped suppressing operator protective guard 32' is regenerated by being combed, brushed, agitated, vibrated or otherwise manipulated to remove accumulation or caught or trapped sparks, spark residue, debris, dust, and the like lodged between spikes 112, attached to spikes 112, stuck to base or base layer, and/or which have otherwise accumulated within the guard 32' during spark suppressor operation. Such a method and spark suppressor regenerator can also be configured to reorient the spikes 112 by straightening, bending, fluffing, or combing the spikes 112 in way that can and preferably does deform them in a manner that makes them stand upwardly or outwardly to return the spikes 112 to more optimal spark energy- absorbing, e.g., spark catching or spark suppressing, efficiency.

[0052] Figures 7 and 8 illustrate a preferred embodiment of a spark suppressor 65' of retrofit construction that is formed of a spark- suppressing strip 116 that includes at least one kinetic spark energy- absorbing layer 118 having a three-dimensionally contoured spark momentum dissipating surface 120 facing outwardly away from the interior spark-deflecting surface 86 of the guard endwall 68 and facing toward the outer peripheral edge 58 of the disc or wheel 50 such that sparks 88 ejected therefrom during workpiece grinding or cutting come into contact with at least part of the outer surface 120 of the outer layer 118 of the strip 116. In a preferred embodiment, the strip 116 includes an anchor layer 122 disposed underneath the outer kinetic spark energy absorbing layer 118 that preferably directly underlies outer layer 118 with the anchor layer 122 used to anchor or attach the strip 116 to the inner spark-deflecting surface 86 of guard endwall 68. One or more such spark suppressing strips 116 can also be attached in like manner to the inner spark-deflecting surface 84 of the outer sidewall 72 of the guard 32' being spark suppression retrofitted. One or more of the layers 118 and 122 can be formed in part or substantially completely composed of a mesh material, e.g., mesh fabric, which can be and preferably is made of metal or metallic construction with a preferred mesh material well suited for use being a metal or metallic micromesh material like that discussed herein above.

[0053] Where the guard 32 is a cutting guard 35 equipped with a pair of opposed and generally parallel guard sidewalls 64 and 72, strips 116 can be attached to the inner spark-deflecting surfaces 84 and 86 of both guard sidewalls 64 and 72 as well as to the inner spark-deflecting surface 85 of the guard endwall 68 to retrofit and produce a spark-suppressing guard 32' of the invention. To provide more optimal retrofit spark suppression, substantially the entire surface area of the internal spark-deflecting surfaces 84, 85 and/or 86 of guard endwall 68 and/or guard sidewalls 64 and/or 72 can be and preferably is composed of (a) a non-smooth spark kinetic energy dissipating inner surface 108 that preferably is of three-dimensionally contoured construction and/or (b) a three-dimensionally contoured spark momentum or energy dissipating outer surface 120 as discussed elsewhere in more detail herein.

[0054] With continued reference to Figures 7 and 8, a preferred spark suppressor 65' preferably has a three-dimensionally contoured spark momentum or energy dissipating outer surface 120 composed of or which includes a spark catcher 124 of fibrillated construction composed of at least a plurality of pairs of, i.e., at least three, spaced apart, elongate and upwardly extending spark travel obstructing elongate wires or pins 126 that collectively form a spark-catching brush 128. In one embodiment, the spark-catching brush 128 has at least a plurality of pairs of spark travel obstructing pins 126 per square centimeter of surface area of the brush 128. In another embodiment, the spark-catching brush 128 has at least one spark-engaging pin 126 per square millimeter of brush surface area. In a preferred embodiment, the spark-catching brush 128 has a plurality of spark energy absorbing pins 126 per square millimeter providing an optimal spark engaging pin density that helps not only absorb momentum of discharged sparks 88 slowing them down, but also preferably catching and/or stopping at least some of the sparks 88. A preferred embodiment of the spark-catching brush 128 employs carding cloth having 0.6 millimeter by 1 millimeter rectangular tempered steel or nickel coated steel pins 126, each of which are at least 8 millimeters in length and which preferably have a standard length of about 12 millimeters or about 0.5 inches. In a preferred embodiment, the pins 126 of the spark catching brush 128 have a length of no greater than 20 millimeters to avoid contact with the abrasive wheel of the tool during grinding or cutting operation of the tool 20.

[0055] In a preferred embodiment, each spark- suppressing strip 116 or spark-catching brush 128 is formed of carding cloth or card cloth 130 with at least fifteen wires or pins 126 per square inch, e.g., 15 pins per square inch (15 PPSI) or 15 teeth per square inch (15 TPI), preferably at least twenty-five pins per square inch, e.g., 25 pins per square inch (25 PPSI) or 25 teeth per square inch (25 TPI) and more preferably at least fifty pins per square inch, e.g., 50 pins per square inch (50 PPSI) or 50 teeth per square inch (50 TPI), of card cloth surface area. Each pin 126 is of made of metal or metallic construction, such as made of tempered steel, nickel coated steel, aluminum, or another type of metal or metal alloy, with each pin 126 preferably being spring biased, resilient and/or flexible for better withstanding spark impacts as well as more efficiently absorbing kinetic energy of sparks 88 impacting the pins 126 to help "catch" sparks during abrasive tool operation. Each pin 126 can be substantially straight, curved, have an angled leg or tip, be generally L-shaped or be generally V-shaped with each pin 126 preferably having a length of at least one millimeter, preferably at least a plurality of millimeters, and more preferably at least a plurality of pairs of millimeters. In one spark suppressing strip or spark catching brush embodiment, each pin 126 has a length of at least two millimeters. In another preferred embodiment, each pin 126 has a length of at least five millimeters. In still another embodiment, each pin 126 has a length of at least eight millimeters.

[0056] In a preferred embodiment, the carding cloth or card cloth 130 is formed of a flexible metallic base layer attached to a metal spark suppressing guard 32' releasably mountable to tool 20 that preferably a metallic mesh material, such as formed of a woven steel mesh, from which the wires or pins 126 extend upwardly. In converting a conventional non-spark suppressing guard 32 into a guard 32' of spark suppressing construction, one or more pieces or strips of carding cloth or card cloth 130 are attached to one or more of the internal surfaces of the guard 32 disposed adjacent to and/or facing toward the rotary abrasive grinding or cutting implement 30 of the tool 20 producing a spark suppressing guard 32' in accordance with the invention.

[0057] During spark arrestor operation, the metal wires or pins 126 and metal base layer of the carding cloth or card cloth mounted to the interior surface of the guard endwall work in concert with one another to rapidly dissipate buildup of heat from sparks caught by the pins 126 or trapped between the pins 126 in contact with the carding cloth base layer helping prevent temperatures greater than the combustion temperature of materials nearby the tool 20. In a preferred embodiment, heat from sparks caught by the pins 126 and/or which come to rest against the base layer that is disposed in direct contact with the guard 32' is rapidly transferred to the metal guard 32' which functions as a heat sink to in turn transfer the heat to the air surrounding the tool 20 during tool operation. As a result, in a preferred embodiment, formation of hot spots having a temperature above 200 degrees Celsius within the guard 32' during tool and spark arrestor operation are advantageously prevented thereby preventing temperatures within the guard 32' reaching a combustion temperature or combustible during rotary abrasive tool operation of fabrics or other combustible materials nearby.

[0058] In one embodiment, strip 116 or brush 128 can be composed of a plurality of spaced apart spark energy absorbing zones with the wires or pins 126' in a first one of the zones being longer, having a larger thickness or diameter, and/or made of a different material than the pins 126" in a second one of the zones that is disposed adjacent or inline the first one of the zones. In another embodiment, strip 116 or brush 128 is composed of a plurality of spaced apart spark energy absorbing zones with the pins 126' in a first one of the zones being oriented at an angle different than the angle of the pins 126" in a second one of the zones. In still another embodiment, strip 116 or brush 128 is composed of a plurality of spaced apart spark energy absorbing zones with the pins 126' in a first one of the zones generating or providing a spark-attracting electrostatic charge, such as for trapping or catching metallic sparks, and a second one of the zones with pins 126" of a non-building or inducing construction that can be and which preferably are pins 126" of non-metallic construction.

[0059] If desired, such a strip 116 or brush 128 can be formed of or include a plurality of pairs of, i.e., at least three, of adjacent zones disposed side-by-side one another with each one of the zones having wires or pins 126', 126" and/or 126"' of a different construction, composition and/or configuration. In one such strip 116 or brush 128, the pins 126' in a first zone disposed closest to where sparks enter the spark-guiding chute 75 has a first pin length for slowing sparks 88 down impacting the pins 126' and accommodating pin wear for a longer period of time, the pins 126' in a second zone disposed downstream of the first zone are formed of a harder material and oriented at a first angle relative to the spark stream with the angle optimizing stopping of sparks 88 impacting pins 126" of the second zone, and the pins 126"' in a third zone disposed downstream of the second zone having a pin height greater than the first and second zones and preferably are angled toward or into the spark stream forming a spark collecting zone disposed at or adjacent the discharge of the chute 75. In another preferred embodiment, the discharge of the chute of the retrofitted spark suppressing protective guard 32' has a closed end, e.g., wall blocking the chute discharge, with the inner surface area of the chute discharge blocking wall being covered with on one or more strips 116 or brushes 128 advantageously providing addition spark stopping, spark catching, spark trapping or spark collecting interior area covered with such pins 126, 126', 126" and/or 126"'.

[0060] With continued reference to Figure 8, in one preferred embodiment, the wires or pins 126, 126' and/or 126" are arranged with different lengths, e.g., alternating differing lengths, and/or with randomly different lengths to facilitate sparks traveling therealong making contact with one or more of the wires or pins 126, 126' and/or 126" helping to absorb spark kinetic energy reducing spark velocity until effectively caught by the mass or wires or pins 126, 126' and/or 126". Where configured with wires or pins 126 or 126' and/or 126, 126' or 126" having at least a plurality of different lengths, wires or pins 126 have one length, wires or pins 126' have a different length than wires or pins 126, and wires or pins 126" have a length different than the length of wires or pins 126 and wires or pins 126' . In one embodiment, wires or pins 126 have a first length, wires and pins 126' have a second length longer than that of wires or pins 126, and, where equipped with wires or pins 126, 126' and 126" having a plurality of pairs, i.e., at least three different lengths, wires or pins 126 have a first length, wires and pins 126' have a second length longer than that of wires or pins 126, and wires or pins 126" have a third length longer than that of wires or pins 126 and wires or pins 126'. In one such preferred embodiment, wires or pins 126, 126' and/or 126" of differing lengths are three-dimensionally formed to engage one another in a non-woven arrangement where the wires or pins 126, 126' and/or 126" are entangled with one another in a manner that produces a porous spark-catching layer 125 in which sparks enter and become trapped during spark suppressor operation.

[0061] During spark suppressing strip or brush operation, sparks 88 discharged from the spark generating region 95 at relatively high velocities contact or impact wires or pins 126 spaced apart along the length of the spark-suppressing strip 116 that forms the spark-catching brush 128 with each spark impact absorbing momentum and/or reducing kinetic energy thereby slowing down at least some of the sparks 88 until enough impacts with spark-energy absorbing spikes 112 cause at least some of the sparks 88 to stop. As best shown in Figures7-9, such a spark suppressor 65' constructed in accordance with the present invention that is formed of, configured with, or includes such a non- smooth three-dimensionally contoured spark momentum or energy dissipating outer surface 120 that includes or is composed of at least a plurality of pairs, i.e. at least three, of such spark-contacting or spark-engaging pins 126 advantageously slows down and preferably stops at least a plurality of pairs of, i.e. at least three, of sparks 88 formed per second of grinding tool or cutting tool operation thereby advantageously reducing the number of sparks 88 in the discharge stream that exits the spark-guiding chute 75 of the spark suppressing protective guard 32' .

[0062] Preferably, such a retrofittable or retrofitted spark suppressor 65, e.g., spark suppressor 65' or spark suppressor 65", constructed in accordance with the present invention formed of such a spark-catching brush 128 configured with a non-smooth three-dimensionally contoured spark momentum or spark energy dissipating outer surface 120 which can be and preferably is formed of or includes at least a plurality of pairs of, i.e. at least three, outwardly extending elongate wires or pins 126, imparts spark suppression to guard 32' sufficient to reduce the amount of sparks 88, volume of sparks 88, and/or volumetric density of the sparks 88 that make up, form or are entrained within the discharge spark stream 94' by at least 20%, preferably by at least 35%, and more preferably by at least 50%, compared to a conventional guard 32 of an abrasive grinding or cutting tool, e.g., grinder, of non-spark suppressing construction that is constructed without any such spark suppression. With continued reference to Figures 7-9 such a spark suppressing guard 32' retrofitted with such spark suppression is configured with at least one spark suppressor 65' that includes, provides or is configured with at least one non-smooth three- dimensionally contoured spark momentum or spark energy dissipating outer surface 120 disposed along at least one of the interior spark-deflecting surfaces 84, 85 and/or 86 of guard 32' or guard 32 into a spark suppressing guard 32' which is formed of or includes at least a plurality of pairs of, i.e. at least three, pins 126, and which can be in the form of at least one spark suppressing strip 116, e.g., one or more spark-catching brushes 128, producing a spark suppressing guard 32' or spark suppressing retrofitted guard 32 in accordance with the present invention which suppresses or reduces the amount of sparks 88, volume of sparks 88, and/or volumetric density of the sparks 88 that make up, form or are entrained within the discharge spark stream 94' by at least 20%, preferably by at least 35%, and more preferably by at least 50%, compared to a conventional guard 32 of a grinder 46 that is of non-spark suppressing construction which is constructed without any such spark suppressor(s) or spark suppressing arrangement, such as that shown in Figure 4.

[0063] Figures 11-17 illustrate a second preferred embodiment of a spark suppressing guard 32" constructed in accordance with the present invention that is formed of a grinding or cutting implement spark-retaining cowling 140 that substantially completely encloses a rotary abrasive grinding or cutting implement 30 of a rotary abrasive tool 20 and which is configured with a rotary abrasive implement access opening 142 through which an object (not shown) to be abraded, e.g., ground or cut, can be received to engage the abrasive implement 30 to grind or cut the object. With specific reference to Figure 11, such a spark suppressing guard 32" is particularly well suited for use with a rotary abrasive tool 20 that is a fire or rescue saw 145 equipped with a rotary implement that is a disc-shaped circular fire or rescue saw blade 147 of a type used for grinding or cutting through steel, aluminum, steel and aluminum alloys, vehicle bodies/frames, guardrails, pipe, chain, rebar, concrete, tile glass, tires, roofing materials, wood and the like. In the preferred embodiment depicted in Figure 11, the spark suppressing guard 32" is configured for use with a fire or rescue saw 145, such as a HUSQVARNA K970 or K1260 fire rescue saw equipped with a circular rotary saw blade 147 that is twelve inches, fourteen inches or sixteen inches in diameter and which can be a toothed blade, a cut-off blade, a grinding blade or another type of suitable circular rotary blade.

[0064] As is best depicted in Figure 11, the spark suppressing guard 32" is formed of a spark- retaining cowling 140 of clamshell construction formed of an internal spark-channeling sleeve 146 formed by parallel cowling sidewalls 148, 150 respectively overlying a substantial portion of opposite sides of the generally circular rotary abrasive grinding or cutting implement 30, e.g. fire or rescue blade 147 with the cowling sidewalls 148, 150 spaced apart by a curved

interconnecting outer cowling endwall 152 disposed radially outwardly of the outer peripheral grinding or cutting edge 60 of the rotary grinding or cutting implement 30. Such a cowling endwall 152 preferably is curved in a manner that defines a generally circular outer periphery 155 of the cowling 140 where the cowling endwall 152 radially tracks, follows or otherwise conforms to the contour of the outer peripheral edge 60 of the rotary grinding or cutting implement 30. Such a spark suppressing cowling 140 of the present invention covers at least a majority, i.e., at least one-half, of the surface area of opposites sides of the rotary grinding or cutting implement 30 and radially outwardly overlies at least a majority, i.e., at least half, of the outer peripheral grinding or cutting edge 60 of the rotary grinding or cutting implement 30 advantageously helping optimize spark suppression by increasing the amount of sparks generated during workpiece grinding or cutting that are captured as a result of encompassing or

encapsulating so much of the rotary grinding or cutting implement 30.

[0065] As also shown in Figure 11, the cowling 140 encompasses an angular or circumferential extent of the rotary grinding or cutting implement 30, e.g., fire or rescue blade 147, of at least 170°, preferably of at least 180°, and more preferably of at least 200° thereby advantageously optimizing capturing of sparks generated during workpiece grinding or cutting. In a preferred embodiment, the cowling 140 preferably encompasses an angular or circumferential extent of the rotary grinding or cutting implement 30 of no larger than 300°, preferably no larger than 285°, and more preferably no greater than about 270°.

[0066] With continued reference to Figure 11, a portion of the cowling 140 not covering or encapsulating the abrasive grinding or cutting implement 30 provides the generally pie-shaped abrasive implement access opening 142 through which a workpiece can enter and engage the abrasive grinding or cutting implement 30 that is rotated by the tool 20 during operation to grind or cut the workpiece. The abrasive implement access opening 142 is defined by or otherwise disposed between a pair of spaced apart and opposed ends 154, 156 of the cowling endwall 152 that extend radially outwardly of the outer peripheral grinding or cutting edge 60 of the grinding or cutting implement 30 to form respective spark intake ports 158, 160 which receive sparks generated during contact between the workpiece and the rotating implement 30. As a result of a circumferential flow of air at or along the outer peripheral edge 60 of the implement 30 caused by rotation of the implement 30, sparks 88 discharge or propelled radially outwardly from the edge 60 of the implement 30 are also propelled in a circumferential direction in the direction of rotation of the implement 30 into one of the spark-receiving intake ports 158 or 160

advantageously capturing the sparks 88 within the cowling 140 thereby catching the sparks 88 in the guard 32". Such a configuration advantageously draws or sucks sparks 88 generated in the contact region between the workpiece and implement 30 into the corresponding spark intake port 158 or 160 downstream of the direction of rotation of the implement 30 during grinding or cutting of the workpiece helping maximize spark capture.

[0067] To help facilitate and optimize retention of sparks 88 captured within the cowling 140, each end 154, 156 of the cowling endwall 152 has a respective flow directing vane 162, 164 extending radially inwardly toward the peripheral edge of the grinding or cutting implement 30 that creates a corresponding adjacent flow restriction that facilitates spark capture and retention. A spark suppressor 65" constructed in accordance with the present invention having a spark suppressing guard 32" formed of a spark-retaining cowling 140 preferably is of bidirectional construction working well no matter which direction the grinding or cutting implement 30 is rotated relative thereto. For the rotational direction indicated by arrow 166 in Figure 11, one of the flow directing vanes 162, 164 is a downstream flow-directing vane 162 disposed downstream of the direction of flow of air propelled circumferentially by the implement 30 in the direction of rotation of the implement 30 and the other one of the vanes 162, 164 is an upstream flow- directing vane 164 disposed upstream of the direction of flow of air propelled circumferentially by the implement 30 in the direction of rotation of the implement 30.

[0068] The downstream flow-directing vane 162 creates a restriction in the circumferentially flowing air that helps draw or suck discharged sparks 88 into the respective downstream intake port 158 even further helping maximize capturing of sparks during tool operation. In addition, the flow expanded portion of the intake port 158 downstream of the downstream vane 162 helps direct sparks 88 entrained in the flowing air radially outwardly toward and preferably into contact with at least one spark-energy absorbing and/or catching interior surface within the cowling 140 that helps suppress, catch and retain the sparks 88 during tool operation.

[0069] The upstream flow-directing vane 164 defines or otherwise forms a spark stop against which any spark 88 still entrained in circumferentially flowing air reaching the discharge port 160 will impinge or stop against vane 164 before exiting the discharge port 160 causing the stopped spark 88 to be retained within and collected by the cowling 140. In a preferred embodiment, the upstream flow-directing vane 164 preferably defines or otherwise forms a recessed spark-collecting pocket within the cowling 140 in which sparks 88 still entrained in flowing air reaching the discharge port 160 are received and retained.

[0070] Such a spark suppressing guard 32" formed of or with such a cowling 140 constructed in accordance with the present invention advantageously directs at least 60% of the sparks 88 generated during grinding or cutting of workpiece with implement 30 into the cowling 140 retaining at least 60% of the sparks 88 received in the cowling 140 during tool operation. In a preferred embodiment, such a cowling 140 constructed in accordance with the present invention advantageously directs at least 60% of the sparks 88 generated during grinding or cutting of workpiece with implement 30 into the cowling 140 retaining at least 75% of the sparks 88 received in the cowling 140 during tool operation. In another preferred embodiment, such a cowling 140 constructed in accordance with the present invention advantageously directs at least 60% of the sparks 88 generated during grinding or cutting of workpiece with implement 30 into the cowling 140 retaining at least 85% of the sparks 88 received in the cowling 140 during tool operation. In still another preferred embodiment, such a cowling 140 constructed in accordance with the present invention advantageously directs at least 60% of the sparks 88 generated during grinding or cutting of workpiece with implement 30 into the cowling 140 retaining at least 95% of the sparks 88 received in the cowling 140 during tool operation.

[0071] In another preferred embodiment, such a cowling 140 constructed in accordance with the present invention advantageously directs at least 75% of the sparks 88 generated during grinding or cutting of workpiece with implement 30 into the cowling 140 retaining at least 60% of the sparks 88 received in the cowling 140 during tool operation. In still another preferred embodiment, such a cowling 140 constructed in accordance with the present invention advantageously directs at least 75% of the sparks 88 generated during grinding or cutting of workpiece with implement 30 into the cowling 140 retaining at least 85% of the sparks 88 received in the cowling 140 during tool operation. In a further preferred embodiment, such a cowling 140 constructed in accordance with the present invention advantageously directs at least 75% of the sparks 88 generated during grinding or cutting of workpiece with implement 30 into the cowling 140 retaining at least 95% of the sparks 88 received in the cowling 140 during tool operation. [0072] In yet another preferred embodiment, such a cowling 140 constructed in accordance with the present invention advantageously directs at least 85% of the sparks 88 generated during grinding or cutting of workpiece with implement 30 into the cowling 140 retaining at least 60% of the sparks 88 received in the cowling 140 during tool operation. In still another preferred embodiment, such a cowling 140 constructed in accordance with the present invention advantageously directs at least 90% of the sparks 88 generated during grinding or cutting of workpiece with implement 30 into the cowling 140 retaining at least 90% of the sparks 88 received in the cowling 140 during tool operation. In a further preferred embodiment, such a cowling 140 constructed in accordance with the present invention advantageously directs at least 95% of the sparks 88 generated during grinding or cutting of workpiece with implement 30 into the cowling 140 retaining at least 95% of the sparks 88 received in the cowling 140 during tool operation.

[0073] In a preferred embodiment, the spark-retaining cowling 140 that defines such a spark suppressing guard 32" of the present invention is configured with an adjustable rotary abrasive implement access opening 142. Such a cowling 140 preferably also is of bidirectional abrasive implement rotation construction 150 by having opposite cowling ends 146 and 148 bracketing the contact region of the rotary abrasive implement 30 within the access opening 144 thereby maximizing capture and retention of sparks 88 generated during operation of the spark- suppressed rotary abrasive or cutting tool 20. No matter which direction the abrasive implement 30 rotates during tool operation, spark suppression and retention is maximized.

[0074] In the preferred embodiment shown in Figures 11-17, the spark-retaining cowling 140 is of multi-piece construction having a first cowling component 168 that preferably is a base 170 of the cowling 140 that encompasses an angular or circumferential extent of the circular implement 30 when mounted to the tool 20 of at least 135°, preferably at least 150°, and more preferably at least about 180° and which has a releasable mount 40 that preferably is or includes a releasable mounting clamp 44 as depicted in Figure 14 to enable quick and releasable fixing of the cowling base 170 to the tool 20. The spark-retaining cowling 140 preferably has a second cowling component 172 that encompasses an angular or circumferential extent of the circular implement 30 of at least 30°, preferably at least 38°, and more preferably at least about 45° and which is attached to the first cowling component 168 or cowling base 170 in a manner that preferably permits removal and re-attachment to the first cowling component 168 or base 170. [0075] In a preferred embodiment, the second cowling component 172 is movably or adjustably attached to the first cowling component 168 or cowling base 170 in a manner that permits the size of the rotary abrasive implement access opening 142 to be changed such as where desired to increase the size of the opening 142 where a larger sized opening 142 is needed or desired. In one preferred embodiment, the second cowling component 172 is operably coupled to the first cowling component 168 or base 170 in a manner where the second component 172 functions as a pivotable spark suppressing "jaw" that pivots about an axis generally parallel to the tool axis of rotation toward the first cowling component 170, to make the rotary abrasive implement access opening 142 smaller in size or angular extent, or away from the first cowling component 170, to make the rotary abrasive implement access opening 142 larger in size or angular extent. In one such preferred embodiment, the second cowling component 172 is pivotably connected to the first cowling component 168 which serves as the base 170 of the cowling 140 that is removably fixed to the tool 20 during spark suppression during tool operation.

[0076] In a preferred embodiment, a spark-retaining cowling 140 of the present invention is of two-piece construction having one cowling half 168 attached to the other cowling half 172 forming a cowling 140 of clamshell- shaped construction that defines a circumferentially extending spark-directing or spark- funneling spark catching sleeve 146 that encompasses an angular and/or circumferential extent of greater than 180°, preferably greater than 200°, and more preferably greater than 220° to capture or suppress at least 60%, preferably at least 75%, and more preferably at least 85% of sparks generated or emitted during abrasive or cutting contact of the rotating implement 30 during tool operation. In one preferred embodiment, a spark-retaining cowling 140 of the present invention extends about an angular and/or

circumferential extent of at least 215°, preferably at least 225°, and more preferably at least 230°, e.g., at least about 235°, producing a spark-catching guard 32" in accordance with the invention that catches or suppresses at least 75° of the sparks generated, preferably at least 85%, and more preferably at least 95% of all of the sparks generated by abrasive contact between a workpiece and the rotating circular implement 30 during grinding or cutting of the workpiece.

[0077] Each one of the cowling halves 168 and 172 has a pair of spaced apart and generally parallel sidewalls 148, 150 with one of the sidewalls 148 overlying one side or surface of the disc-shaped body of the rotary abrasive grinding or cutting implement 30 and the other one of the of the sidewalls 150 overlying the opposite side or surface of the disc-shaped body of the implement 30 that are spaced apart by an elongate curved outer cowling endwall 152 that extends radially outwardly of the outer peripheral edge 60 of the implement 30. With additional reference to Figures 15 and 17, at least the endwall 152 of at least one of the cowling halves 168 or 172 and preferably the endwall of both cowling halves 168 and 172 is of spark kinetic energy absorbing construction and can also be of three-dimensionally contoured spark catching construction preferably by being equipped with a spark kinetic-energy dissipating interior surface 108 that preferably is provided by at least a plurality of pairs, i.e., at least three, spark energy absorbing projections 110 per square centimeter of cowling endwall surface area with the projections 110 preferably uniformly spaced apart therealong. With continued reference to Figures 15 and 17, the endwall 152 of each cowling half 168 and 172 preferably is comprised of an elongate spark suppressing strip 116, such as constructed in accordance with that described above, with the upraised projections 110 being upraised wires or pins 126 that dissipate or otherwise absorb spark energy and/or catch sparks during rotary grinding or cutting tool operation. In a preferred embodiment, an elongate upraised projection-carrying arrangement, preferably in the form of a pin carrying- spark catching brush 128 or card, e.g., card cloth 130, is carried or otherwise anchored to the interior surface of one or both cowling sidewalls 148 and/or 150, and/or the cowling endwall 152, to slow, stop and/or catch sparks generated that are radially outwardly flung into the projections 110, preferably pins 126, of the spark-catching brush 128 or card 130.

[0078] An interior surface of each one of the cowling sidewalls 148, 150 of one or both cowling halves 168 and/or 172 that faces a respective outer disc surface of the implement 30 can be and preferably also is configured with a three-dimensionally contoured spark kinetic-energy dissipating surface, such as a kinetic-energy dissipating surface comprised of one or more spark- suppression strips 116 of three-dimensionally contoured construction that can and preferably is comprised of spaced apart upraised spark energy absorbing projections 110 that can be and preferably are or include outwardly extending wires or pins 126. In this regard, the internal cowling surface of one or both cowling sidewalls 148 and/or 150 can have one or more spark suppression strips 116 attached thereto in addition to the spark suppression strip 116 attached to the inner cowling surface of the curved radial outer endwall 152 of cowling half 168 shown in Figure 15, if desired. In addition, the internal cowling surface of one or both cowling sidewalls 148 and/or 150 can have one or more spark suppression strips 116 attached thereto in addition to the spark suppression strip 116 attached to a portion of the inner surface of sidewall 148 and in addition to the spark suppression strip 116 attached to the inner cowling surface of the curved radial outer endwall 152 of cowling half 172 shown in Figure 17, if desired.

[0079] With reference to Figures 11-13 andl6-17, one or both cowling halves 168 and/or 172 can have one or more spark suppressing strips 116 disposed about or adjacent the central axis 49 of the rotary abrasive implement 30, e.g., grinding wheel or cutting disc, which can and preferably do extend about at least a portion of the periphery of the rotary abrasive implement access opening 142 to provide a spark-catching seal thereabout. In this regard, Figures 16 and 17 illustrate at least a portion of cowling 140, namely one of the cowling halves 172, equipped with at least one spark-entrained air flow sealing spark suppressing strips 116 that are equipped with upraised projections in the form of spark energy dissipating wires or pins 126 which seal sparks 88 within the cowling 140 by catching sparks 88 in airflow exiting the cowling 140 at or adjacent access opening 142.

[0080] In a preferred embodiment, the tool 20 is a fire or rescue saw equipped with such a spark- retaining cowling 140 that provides a spark suppressing guard 32" of the present invention extending about a cutting saw blade or grinding disc abrasive implement 30 used during fire and rescue situations to cut through metal and other materials during potentially lifesaving use.

Because of attachment of such a guard 32" to such a fire or rescue saw configured with such a cowling 140 that extends at least 180° about the saw, preferably at least 230° about the saw, at least 60%, preferably at least 70%, and more preferably at least 85% of the sparks generated by the saw during cutting are suppressed by being retained or contained within the cowling 140. By catching and preventing at least at least 60%, preferably at least 70%, and more preferably at least 85% of the sparks generated by the saw during cutting, situations where such sparks could set off combustible gas or liquid fuel adjacent the area being cut by the tool are prevented advantageously enhancing safety.

[0081] Where equipped with such a spark suppressing guard constructed in accordance with the claimed invention, the spark suppressing guard can be of snap-fit or clip-on construction as known in the art. In one preferred embodiment, a spark suppressing guard of the present invention is of two-piece construction having a portion attached to the rotary abrasive tool and the arcuate shroud or cover portion that is configured for snap-on, click-on, snap-off, click-off construction. Such a spark suppressing guard constructed in accordance with the present invention can have a guard or shroud construction similar to or substantially same as the click on and click off two-piece guard assembly shown in United States Patent Application Publication No. 20060068690, entitled "Cover Device for a Power Tool," the entire disclosure of which is hereby expressly incorporated herein by reference. Where equipped with such a two-piece guard assembly, the removable portion of the guard assembly preferably is of spark suppressing construction constructed of one or more of the above-described spark suppressing, spark energy dissipating, and/or spark momentum absorbing surfaces, structures and the like of the present invention.

[0082] Understandably, the present invention has been described above in terms of one or more preferred embodiments and methods. It is recognized that various alternatives and modifications can be made to these embodiments and methods that are within the scope of the present invention. It is also to be understood that, although the foregoing description and drawings describe and illustrate in detail one or more preferred embodiments of the present invention, to those skilled in the art to which the present invention relates, the present disclosure will suggest many modifications and constructions as well as widely differing embodiments and applications without thereby departing from the spirit and scope of the invention. The present invention, therefore, is intended to be limited only by the scope of the appended claims.

Claims

CLAIMS:

1. A spark suppressor for an abrasive power tool comprised of at least one spark momentum dissipating or spark kinetic energy reducing surface disposed adjacent to a spark generating region where an abrasive implement of the abrasive power tool contacts a workpiece being abraded thereby with the at least one spark momentum dissipating or spark kinetic energy reducing surface or layer being of a non-smooth surface construction configured to dissipate momentum or absorb kinetic energy of one or more sparks generated and expelled, propelled or ejected from the spark generating region.

2. The spark suppressor of claim 1, wherein the at least one spark momentum dissipating or spark kinetic energy reducing surface or layer is comprised of a non-smooth outer surface disposed adjacent the spark generating region.

3. The spark suppressor of claim 2, wherein the at least one spark momentum dissipating or spark kinetic energy reducing surface or layer is comprised of a non-smooth outer surface that faces generally toward the spark generating region.

4. The spark suppressor of claim 2, wherein the at least one spark momentum dissipating or spark kinetic energy reducing surface or layer is comprised of a non-smooth outer surface disposed downstream of the spark generating region.

5. The spark suppressor of claim 2, wherein the at least one spark momentum dissipating or spark kinetic energy reducing surface or layer is three-dimensionally contoured and comprised of at least a plurality of pairs of upraised spark impacting portions spaced apart from other upraised spark impacting portions.

6. The spark suppressor of claim 5, wherein the plurality of pairs of upraised spark impacting portions each comprises at least one elongate projection extending outwardly generally toward one of the abrasive implement, workpiece and spark generating region.

7. The spark suppressor of claim 6, wherein each one of the elongate outwardly extending projections comprises a spike.

8. The spark suppressor of claim 7, wherein the at least one spark momentum dissipating or spark kinetic energy reducing surface or layer is comprised of at least one of the spike per square millimeter of area thereof.

9. The spark suppressor of claim 7, wherein the at least one spark momentum dissipating or spark kinetic energy reducing surface or layer is comprised of at least a plurality of pairs of the spikes spaced apart therealong and forming an elongate spark suppressing strip.

10. The spark suppressor of claim 7, wherein each spike comprises an elongate wire or pin.

11. The spark suppressor of claim 9, wherein the at least one spark momentum dissipating or spark kinetic energy reducing surface or layer is comprised of at least a plurality of the wires or pins per square millimeter of area thereof.

12. The spark suppressor of claim 5, wherein the at least one spark momentum dissipating or spark kinetic energy reducing surface or layer is comprised of an elongate spark suppressing strip attached to an interior surface of the guard facing the abrasive implement, the elongate spark suppressing strip formed of a temperature resistant material having a melting point of at least 350 degrees Fahrenheit.

13. The spark suppressor of claim 12, wherein the spark suppressing strip is elongate and comprised of a metallic mesh.

14. The spark suppressor of claim 13, wherein the metallic mesh of the elongate spark suppressing strip is comprised of stainless steel.

15. The spark suppressor of claim 12, wherein the spark suppressing strip is flexible and comprised of a plurality of pairs of upraised spark energy dissipating spikes.

16. The spark suppressor of claim 12, wherein the spark suppressing strip comprises a spark catching brush having a plurality of pairs of metal wires extending outwardly thereof.

17. The spark suppressor of claim 12, wherein the spark suppressing strip is of regenerative construction.

18. The spark suppressor of claim 12, wherein the spark suppressing strip is configured to be removable or replaceable.

19. The spark suppressor of claim 18, wherein the spark suppressing strip is configured to be disposable.

20. The spark suppressor of claim 12, wherein the spark suppressing strip is removably received in a holder attached to an interior portion of the guard or releasably clipped to an interior portion of the guard.

21. The spark suppressor of claim 20, wherein the strip comprises an adhesive strip adhesively affixed to an interior surface of the guard.

22. The spark suppressor of claim 1, wherein the at least one spark momentum dissipating or spark kinetic energy reducing surface or layer is comprised of an elongate brush having an elongate base layer from which at least a plurality of pairs of spaced apart wires outwardly extend along substantially the entire surface of the brush.

23. The spark suppressor of claim 22, wherein the base layer of the brush is comprised of a temperature resistant material having a temperature of at least 500 degrees Fahrenheit.

24. The spark suppressor of claim 22, wherein the base layer of the brush is comprised of a metallic mesh, wherein the wires extend outwardly from the metallic mesh.

25. The spark suppressor of claim 22, wherein the metallic mesh is comprised of stainless steel.

26. The spark suppressor of claim 22, wherein the metallic mesh is comprised of a micromesh material.

27. The spark suppressor of claim 1, wherein the at least one spark momentum dissipating or spark kinetic energy reducing surface is comprised of card cloth or carding cloth.

28. The spark suppressor of claim 27, wherein the card cloth or carding cloth is comprised of at least a plurality of pairs of spaced apart outwardly extending spark momentum absorbing or spike kinetic energy reducing spikes.

29. The spark suppressor of claim 28, wherein each one of the spark momentum absorbing or spike kinetic energy reducing spikes is comprised of an elongate wire.

30. The spark suppressor of claim 29, wherein each wire is of metallic construction.

31. The spark suppressor of claim 30, wherein each wire is made of steel, copper, aluminum or an alloy thereof.

32. The spark suppressor of claim 28, wherein each wire is comprised of carbon, graphite or graphene.

33. The spark suppressor of claim 28, wherein each wire is comprised of a composite or fibrous material.

34. The spark suppressor of claim 28, wherein each wire is comprised of a carbon or glass fiber material.

35. The spark suppressor according any one of the claims 1 to 34, wherein each spike or wire is of non-straight construction.

36. The spark suppressor according any one of the claims 1 to 34, wherein each spike or wire is angled.

37. The spark suppressor according any one of the claims 1 to 34, wherein each spike or wire is fibrillated or of fibrillated construction.

38. The spark suppressor according any one of the claims 1 to 34, wherein each spike or wire is further comprised of a plurality of fibers or tendrils extending outwardly thereof.

39. The spark suppressor of claim 1, wherein the at least one spark momentum dissipating or spark kinetic energy reducing surface is comprised of a carding brush having at least a plurality of pairs of spaced apart outwardly extending spark momentum absorbing or spike kinetic energy reducing spikes.

40. The spark suppressor of claim 1, further comprising a protective guard carried by or which at least partially in shrouds the abrasive implement of the abrasive power tool during abrading of the workpiece, and wherein the at least one spark momentum dissipating or spark kinetic energy reducing surface is interiorly disposed within the protective guard.

41. The spark suppressor of claim 40, wherein the abrasive implement comprises a rotary grinding disc or cutting wheel, wherein the guard is comprised of a curved end wall extending circumferentially around a portion of the circumference or outer peripheral edge of the grinding disc or cutting wheel, and wherein at least a portion of an interior surface of the end wall of the guard that faces radially inwardly toward at least a portion of the outer peripheral edge of the grinding disc or cutting wheel is comprised of the at least one spark momentum dissipating or spark kinetic energy reducing surface.

42. The spark suppressor of claim 41, wherein the at least one spark momentum dissipating or spark kinetic energy reducing surface is comprised of a non-smooth and/or three

dimensionally contoured outer surface.

43. The spark suppressor of claim 42, wherein the at least one spark momentum dissipating or spark kinetic energy reducing surface is comprised of a spark suppressing strip carried by the end wall of the guard.

44. The spark suppressor of claim 43, wherein the spark suppressing strip is comprised of at least one layer attached to the end wall of the guard and which is comprised of a temperature resistant material having a melting point of at least 750 degrees Fahrenheit.

45. The spark suppressor of claim 44, wherein the spark suppressing strip is elongate and comprised of a metallic mesh.