Clamshell vacuum dust extraction apparatus for a percussive air tool

A vacuum dust extraction apparatus for a percussive air tool contains and extracts workplace dust created by the impacting action of the air tool's implement. The apparatus includes a clamshell adapter constructed as two halves that are oppositely disposed about the air tool's retainer, and joined to enclose the retainer, and a tubular dust bellows fastened to the outboard end of the joined clamshell halves. The clamshell adaptor includes an integral exhaust port, and an industrial vacuum coupled to the exhaust port via a flexible suction/vacuum hose creates suction in the bellows for extracting airborne dust created by percussive action of the implement on a workpiece. Suction loss through the clamshell adaptor is minimized by a sealing element that bridges a gap between the interior periphery of the clamshell adaptor and the exterior periphery of the air tool's retainer.

TECHNICAL FIELD

This invention relates to a vacuum dust extraction system for a percussive air tool such as a chisel hammer or rivet buster, and more particularly to an apparatus secured to the air tool for containing and extracting airborne dust created by the percussive action of the air tool.

BACKGROUND OF THE INVENTION

Pneumatically operated percussive air tools such as pick or chisel hammers, rivet busters, and so forth are frequently used in industrial applications, and various expedients have been employed to minimize or contain airborne dust produced by the percussive action of the air tool's implement. As disclosed, for example, in the U.S. Pat. No. 7,740,086 to Bleicher et al. and U.S. Pat. No. 9,022,702 to Kasuya et al., this can be achieved with a dust containment hood attached to the implement end of the air tool's housing and an industrial vacuum that draws dust out of the dust containment hood and captures it for later disposal.

While this approach is effective, air tools can vary considerably depending on their rating and type, so that a dust containment hood designed to work with one type of air tool will not necessarily work with other air tools. Also, the dust containment hood must be securely attached to the air tool so that it stays in place during use and transportation of the air tool. Accordingly, what is needed is an improved dust extraction apparatus that is applicable to a variety of air tools, and that is robust, and easily and securely installed on an air tool.

SUMMARY OF THE INVENTION

The present invention is directed to an improved vacuum dust extraction apparatus for a percussive air tool for containing and extracting workplace dust created by the impacting action of the air tool's implement. The improved apparatus includes a clamshell adapter constructed as two halves that are oppositely disposed about an air tool's implement retainer, and joined to enclose the retainer, and a tubular dust bellows fastened to the outboard end of the joined clamshell halves. The clamshell adaptor includes an integral exhaust port, and an industrial vacuum coupled to the exhaust port via a flexible suction/vacuum hose creates suction in the bellows for extracting airborne dust created by percussive action of the implement on a workpiece. Suction loss through the clamshell adaptor is minimized by a sealing element that bridges a gap between the interior periphery of the clamshell adaptor and the exterior periphery of the air tool's retainer.

DESCRIPTION OF THE PREFERRED EMBODIMENT

In general, the clamshell vacuum dust extraction apparatus of this invention is applicable to a variety of percussive air tools, such as chipping hammers, riveting hammers, rivet busters, demolition tool drivers, pavement breakers, rock drills, and so on. By way of example, the vacuum dust extraction apparatus of this invention is illustrated as applied to an otherwise conventional percussive chisel hammer air tool. InFIG. 1, the chisel hammer, generally referred to herein simply as an air tool, is generally designated by the reference numeral10.

Referring toFIG. 1, the air tool10includes a tubular barrel12fitted with a handle14at one axial end and a retainer16at the other axial end. The handle14, which may take various other shapes (D-shaped, or T-shaped, for example), includes an inlet port14aadapted to be coupled to a source of compressed air by the air hose18, an internal air passage coupling the inlet port14ato a piston20by way of a control valve (not shown) operated by a trigger14bintegrated into the handle14. The implement or tool22, a chisel in the illustration ofFIG. 1, is received within the barrel12, and the retainer16is locked onto the barrel12with a retainer spring24(removably inserted through a slot opening16ain the sidewall of retainer16; seeFIGS. 2-3) to retain the chisel22within the barrel12.

The vacuum dust extraction apparatus includes a dust extraction unit generally designated by the reference numeral30, an industrial vacuum34, and a flexible suction hose36coupling the dust extraction unit30to the vacuum34. In general, the dust extraction unit30includes a flexible dust bellows or boot38with accordion-style pleating, and a clamshell adaptor40coupling the bellows38to the air tool10. The body of bellows38surrounds the chisel22, extending substantially to the chisel's tip as shown inFIG. 1. Preferably, the bellows38is relatively transparent so as to not obstruct the user's view of the chisel22and the workpiece in the area of the chisel's tip; this also allows the user to visibly confirm that the bellows38is not getting clogged with dust. The inboard end of dust bellows38slides over a tubular sleeve44on the outboard end of clamshell adaptor40. The suction hose36is coupled to an integral outlet port45of clamshell adaptor40, and dust generated by the action of the chisel22is drawn out of the dust bellows14and into the suction hose36by way of an annular cavity46between the chisel22and the interior periphery of the clamshell adaptor40.

The illustrated industrial vacuum34generally comprises a standard 5-gallon metal pail or canister48and a metal lid50releasably secured to the upper rim of canister48. The downstream end of suction hose36is fastened to the inlet of a vacuum port52mounted on the lid50, and a vacuum unit54also mounted on the lid50creates a suction in the canister48that draws dust-laden air from the dust extraction unit30into the canister480, and then exhausts clean air to atmosphere. Although not shown inFIG. 1, the sidewall of the canister48preferably includes a number of circumferential ribs to impart additional stiffness and resistance to flexure.

The vacuum unit54is preferably a pneumatic vacuum operated by compressed air supplied from an air hose56; the vacuum unit54includes a venturi58, and the compressed air is directed into venturi58through a distributed array of internal air passages (not shown) to create suction upstream of venturi58. In this case, the downstream or outlet end of the venturi58is vented to atmosphere through an exhaust diverter60, and the upstream or inlet end of venturi58is coupled to a venturi mount62fastened to the lid50of canister48.

As indicated inFIG. 1, a volume of water64(referred to herein as the confined water) is placed in the bottom of the canister48, to a depth of approximately 3 inches, and the dust-laden air entering canister48via vacuum port52is cleansed of dust by a water filtration unit66housed within the canister48and partially submerged in the confined water64. The vacuum34also includes a baffle disk68disposed in the upper portion of the canister48, so that the cleansed air exiting water filtration unit66passes through the baffle disk68prior to being exhausted to atmosphere though the venturi58of vacuum unit54. The purpose of the baffle disk68is primarily to prevent any of the confined water64from entering the venturi58.

The water filtration unit66includes a cylindrical velocity ring70supported on the bottom or floor of canister48, and a pipe72extending downward from the vacuum port52and into the velocity ring70. The confined water64is free to flow under the velocity ring70, filling it to substantially the same depth as the rest of the confined water64, and the pipe72extends down into the confined water58within velocity ring70. The bottom of the pipe72is closed, and a small circular opening (not shown) in the sidewall of pipe72just above its closed end defines an exit port through which the dust-laden air entering vacuum port52must pass. In general, the dust-laden air exits the circular opening in pipe72well below the surface of the confined water64in a high velocity stream that creates a high degree of turbulence in the confined water within velocity ring70. This creates a frothy mixture that bubbles up and out of the velocity ring70, and into the interior volume of the canister48. The turbulent mixing of dust-laden air and confined water64within the velocity ring70tends to very thoroughly saturate or wet the airborne dust so that the air released into the canister48in the space between the confined water64and baffle disk68, and thereafter exhausted through the venturi58, is virtually free of dust.

FIGS. 2-4depict the clamshell adaptor40and its usage in more detail. As best seen in the exploded view ofFIG. 2, the clamshell adaptor40includes first and second complementary halves40a,40bthat are joined to create a unitary part that encapsulates the air tool retainer16and provides connection points for both the suction hose36and the bellows38. As seen inFIGS. 2-4, the mating faces of the clamshell halves40a,40bare provided with complementary alignment features—such as the pills47on clamshell half40aand the corresponding recesses (not shown) on the clamshell half40b—to aid in mating alignment and to resist relative movement of the mated halves40a,40b. With the clamshell halves40a,40bso joined, they are fastened together with a pair of elastic O-rings41a,41bseated in circumferential grooves42a,42bformed on the exterior peripheries of the clamshell halves40a,40b. As shown inFIG. 3, at least one of the clamshell halves40a,40bcan be provided with sidewall openings43a,43bthat overlap the circumferential grooves42a,42bto facilitate subsequent user removal of O-rings41a,41bwhen it is desired to separate the dust extraction unit30from the air tool10.

With the two clamshell halves40a,40bjoined, their mating features form a first interior compartment80that closes around the retainer16, and a second interior compartment82that couples the bellows38to the suction hose36. The inboard and outboard compartments80,82are separated by a shoulder84that depends radially inward from the inner periphery of the adaptor sidewall86. The inboard compartment80extends to the inboard end of the adaptor40, and terminates in a radially inward depending flange88. With the two clamshell halves40a,40bjoined around the retainer16, the shoulder84and flange88close around the front and rear axial faces of the retainer16to securely fasten the clamshell adaptor40to the retainer16, and hence, the air tool10. The interior compartment82is axially outboard of the interior compartment80, and serves as a plenum through which dust laden air in the bellows38is drawn into the suction hose36. Thus, the interior compartment82is open to both the tubular sleeve44at the axially outboard end of clamshell adaptor40, and the outlet or suction port45in the sidewall86of clamshell adaptor40.

Although the shoulder84and flange88secure the clamshell adaptor40to the retainer16, they do not form a seal as such, and the suction of industrial vacuum54could draw atmospheric air into the space between the retainer16and the clamshell adaptor40. To minimize any such suction loss, the clamshell adaptor40additionally includes a sealing element90just outboard of the flange88. As best seen inFIG. 4, the sealing element90, which may be cylindrical fiber material, is partially received in a semi-circular groove92formed on inner periphery of the clamshell adaptor's sidewall86. The sealing element90is secured in the groove92with a suitable adhesive, and protrudes out of the groove92to seal the small gap between the clamshell adaptor's sidewall86and the retainer16. And as seen inFIG. 1, the sealing element90is disposed inboard of the retainer spring24that secures the retainer16to the air tool's barrel12.

In summary, the clamshell vacuum dust extraction apparatus of the present invention operates to efficiently and effectively contain and extract workplace dust produced by percussive impacting of an air tool's implement on a workpiece. The various elements of the apparatus may be sized differently than shown, and may be constructed of metal or plastic, as appropriate. And of course, it will be recognized that while the invention has been described in reference to the illustrated embodiments, numerous modifications and variations in addition to those mentioned herein will occur to those skilled in the art. Accordingly, it will be appreciated that systems incorporating these and other modifications and variations still fall within the intended scope of the invention.