Elongated-member-driving apparatus – With means to move or guide member into driving position – Adaptable to dispense different sizes or quantities of members
Reexamination Certificate
2002-05-24
2004-10-26
Smith, Scott A. (Department: 3721)
Elongated-member-driving apparatus
With means to move or guide member into driving position
Adaptable to dispense different sizes or quantities of members
C227S119000, C227S120000, C227S136000
Reexamination Certificate
active
06808101
ABSTRACT:
FIELD OF THE INVENTION
This invention relates generally to improvements in fastener driving tools, and specifically to such tools designed to utilize fastener of varying sizes. The present tool automatically adjusts to different sized fasteners to reduce jamming, making the tools easier to use and having more accurate fastener delivery.
BACKGROUND OF THE INVENTION
Power framing tools for use in driving fasteners into workpieces are well known. The framing tools are usually portable and are powered pneumatically or by combustion. Similar pneumatic tools are described in U.S. Pat. Nos. 4,932,480; 3,552,274 and 3,815,475, all of which are incorporated by reference. Combustion powered tools are described in commonly assigned patents to Nikolich, U.S. Pat. Nos. Re. 32,452; 4,403,722; 4,483,473; 4,483,474; 4,552,162; 5,197,646 and 5,263,439, all of which are incorporated herein by reference. Such combustion powered tools particularly designed for trim applications are disclosed in commonly assigned U.S. Pat. No. 6,016,622, also incorporated by reference herein. Similar combustion powered nail and staple driving tools are available from ITW-Paslode under the IMPULSE® brand.
Such tools incorporate a generally pistol-shaped tool housing enclosing the power source, such as a pneumatic cylinder or a small internal combustion engine. The engine is powered by a canister of pressurized fuel gas also called a fuel cell. Power is generated from expansion of compressed gasses, either by burning of fuel in a combustion chamber or expansion of air in the pneumatic cylinder. The power source moves a reciprocating piston having an elongate, rigid driver blade disposed within a piston chamber of a cylinder body. A safety interlock prevents firing of the tool unless a workpiece contact element at the end of a nosepiece, or nosepiece assembly, is pressed against a workpiece.
Upon the pulling of a trigger, gas or air expansion causes the piston and the driver blade to be shot downward to impact a positioned fastener and drive it into the workpiece. As the piston is driven downward, a displacement volume enclosed in the piston chamber below the piston is forced to exit through one or more exit ports provided at a lower end of the cylinder. After impact, the piston then returns to its original or “ready” position through differential gas pressures within the cylinder. Fasteners are fed into the nosepiece barrel from a supply assembly, such as a magazine, where they are held in a properly positioned orientation for receiving the impact of the driver blade. The fasteners are then propelled through the length of the barrel by the driver blade, exiting the barrel at the workpiece surface. Force of the driver blade and the momentum of the fastener drives the fastener to penetrate the workpiece.
Framing tools are commonly used in residential construction primarily for driving nails into wood. Metal hardware pieces, such as joist hangers, connecting plates and seismic strapping are frequently attached to the wood framing requiring relatively accurate placement of the fastener in openings or slots in the metal hardware. A POSITIVE PLACEMENT® tool is a specialty framing tool that is used where accurate placement of the fastener is desirable. This tool has a probe that aids alignment of the fastener with the hardware openings.
At least two different lengths of nail, 1½″ and 2½″, are typically used for these applications. Current designs for these tools require the user to change settings on the tool when changing between different nail lengths. The user must first pull on a spring-biased plunger to disengage it from a rebound lever. The rebound lever pivots approximately 60 degrees about a pin. While holding the plunger in the outward position, the lever must be rotated via the handle to the other position. When the plunger is released, it again engages with the lever to lock it into the new position. Such an operation requires two hands, one to hold the tool and the other pull the plunger, rotate it and allow it to reengage. In construction environments, the user is often in an inconvenient place, trying to align two or more workpieces to be fastened together. It is not always practical to free both hands to effect the setting change.
In currently available tools, there is also no mechanism for prohibiting the user from loading short nails into the magazine when the lever is set for the long nails. When set for long nails, there is a longer opening to the nosepiece permitting entry of the nail. If the tool is operated in this condition, the short nails can rotate before they travel the length of the opening, causing a jam. The driving mechanism can become wedged between the nail and the nosepiece, causing it to become stuck and rendering the tool inoperable. This condition has been the cause of many field failures of the tool.
Rotation or tumbling of a short nail as it is being driven also leads to inaccuracies in the flight of the nail. Dimensional differences of the fasteners allow more freedom of movement of smaller fasteners within the barrel. Lateral movement of the nail as it travels down the barrel permits the nail to exit the barrel at random orientations compared with the vertical axis of the barrel. Precise nail placement is attained when the fasteners travel a consistent path through the nosepiece. Reduction of rotation of the nail results in better nail control, allowing more accurate nail placement.
The problem of accuracy when using short fasteners is addressed in U.S. Pat. No. 6,279,808 to Larsen, herein incorporated by reference. Larsen discloses a two-piece nail gun guide having a biased arm that protrudes into the barrel, exerting a force on each nail as the nail travels down the barrel and passes by the arm. The biasing force of the arm pushes each nail to one side of the nail gun barrel, increasing the accuracy and consistent orientation of the nail as it exits the barrel. However, this mechanism exerts the biasing force on the fastener as it exits the nosepiece, not as it enters the barrel. It does not prevent jamming of short fasteners due to tumbling as they enter the barrel. Nor does this reference teach or imply that the nail guide serves as an automatic adjustment for fasteners of differing lengths.
Another difficulty with current nosepiece designs is the potential for build-up of collation paper in the barrel. Generally, when the driver blade contacts the fastener, propelling it through the barrel and into the workpiece, the fastener is rapidly torn from the collation paper. The paper may continue to cling to the fastener, or it may remain attached to the subsequent fastener. If portions of the paper are carried through the barrel with the fastener, it will come loose and immediately be dispersed with the fastener penetrates the workpiece. However, sometimes the paper is pushed aside by the fastener and driver blade and remains attached to the next fastener. When this occurs the collation paper can prohibit this next fastener from fully entering the barrel. Firing the tool in this condition results in poor nail control and may result in a jam.
It is an object of the present invention to provide an improved fastener driving tool which adjusts to varying fastener size without requiring manual intervention from the user.
Another object of this invention is to provide an improved fastener driving tool with more accurate placement of short fasteners.
Still another object of this invention is to provide an improved fastener driving tool that reduces jamming of the fastener in the nosepiece.
Yet another object of this invention is to provide an improved fastener driving tool that allows collation paper to be removed from the barrel of the tool before it jams.
SUMMARY OF THE INVENTION
These and other objects are met or exceeded by the present invention which features a nosepiece and shear block assembly that automatically adjusts the length of the nosepiece barrel to accommodate fasteners of differing sizes.
More specifically, the present invention provides a nosepie
Laubach Marco
Walthall Barry
Breh Donald J.
Croll Mark W.
Illinois Tool Works Inc.
Smith Scott A.
Soltis Lisa M.
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