Cutlery – Cutting tools – Saw
Reexamination Certificate
2001-09-17
2003-01-07
Watts, Douglas D. (Department: 3724)
Cutlery
Cutting tools
Saw
C279S074000, C279S079000
Reexamination Certificate
active
06502317
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates in general to power tools. In particular, the present invention relates to a saw blade clamping arrangement for a power tool having a saw blade mounted for reciprocating cutting motion. More specifically, but without restriction to the particular embodiment and/or use which is shown and described for purposes of illustration, the present invention relates to a saw blade clamping arrangement for a power tool including a saw blade ejection mechanism.
2. Discussion
Power reciprocating saws include jigsaws and other reciprocating saws generally referred to in the trade as “recip” saws. These saws incorporate reciprocating shafts for driving generally linear saw blades along a predetermined path so as to provide one of a rectilinear or orbital cutting action.
In a conventional manner, the saw blades used with such power tools are attached to the reciprocating drive shafts through a blade holder having a slot for receiving the saw blade and a set screw which is received in a hole in the blade. The blade is clamped in place relative to the reciprocating drive shaft through tightening of the set screw. While this manner of saw blade attachment has proven to be generally satisfactory and commercially successful, it is not without inherent disadvantages.
For example, power reciprocating saws are subject to high vibration forces during operation which frequently result in loosening of the set screw. If the set screw does not remain sufficiently tightened, the saw blade may become disengaged from the drive shaft. An additional disadvantage with the conventional mounting of saw blades to reciprocating drive shafts relates to an inability to quickly and easily remove saw blades which become worn or fractured. Because it is often desirable to cut a workpiece with minimum material loss, it is desirable to correspondingly minimize the saw blade thickness. As a result, breakage due to the forces encountered during typical use is not an uncommon occurrence. This potential frequency of blade changing makes the ease and rapidity of such action desirable. A further disadvantage of conventional blade mounting arrangements is the necessity for a separate tool such as a wrench for fixation and removal of the saw blade.
Many previous attempts have been made to overcome the disadvantages associated with the above-described conventional mounting of saw blades through elimination of the use of a set screw. One example of such a saw blade mounting arrangement is shown in U.S. Pat. No. 5,322,302. The saw blade mounting arrangement described in this patent includes a mounting body which urges a clamping sphere through the biasing force of a spring into clamping engagement with a saw blade. Removal of the saw blade is facilitated through actuation of a lever which serves to overcome the biasing force exerted by the spring. Operation of this device requires a first of the operator's hands to actuate the lever and a second of the operator's hands for removal or installation of the saw blade. In other words, the actuating lever of this device is not movable to a stable, non-clamping position and necessarily requires two-handed operation—an action which is not always convenient.
Other previous attempts to secure saw blades to a reciprocating drive shaft of a power tool without the conventional use of a set screw are shown in U.S. Pat. Nos. 3,542,097; 3,823,473; 4,020,555; 4,106,181; 4,441,255; 4,594,781; 4,470,196; 4,528,753; 4,601,477; 4,648,182; 5,113,565; 5,263,972; and 5,324,052.
In general, each of the devices shown in these patents represents an attempt to overcome one or more of the disadvantages associated with conventional set screw attachment of a saw blade to a reciprocating drive shaft, including but not limited to the disadvantages discussed above. However, all of these devices are subject to further refinement and improvement. For example, many of the devices, including U.S. Pat. No. 5,322,302, disadvantageously require two-handed operation. Additionally, most of the devices shown in these patents are complicated and expensive to manufacture and assemble as a result of a construction including many separate parts. Further, operation of many of the prior devices requires application of force which is often significant for securing the saw blade in place and loosening of the blade for separation from the drive shaft. Achieving a sufficient force often requires the use of a wrench or other tool. Other disadvantages associated with these prior devices include an inability to cooperate with conventionally shaped saw blades.
SUMMARY OF THE INVENTION
The present invention comprises an improvement over prior-known blade mounting arrangements for power tools, including those disclosed in the aforementioned patents. More particularly, the present invention provides a new and improved saw blade mounting arrangement for a power reciprocating saw which includes a release lever operative to permit quick and easy installation and removal of a saw blade. In the preferred embodiments of the present invention to be described in detail below, the release lever is pivotally mounted for movement between two stable positions. Further in the preferred embodiments, the release lever is not interconnected with the drive shaft for reciprocating movement therewith.
Rather, the release lever is pivotally attached to the housing, thereby reducing the mass carried by the reciprocating shaft. Advantageously, the present invention provides a power reciprocating saw in which the saw blade can be mounted in place and detached using only a single hand. Additionally, the present invention provides a saw blade mounting arrangement for a power reciprocating saw of simple construction which is relatively inexpensive to manufacture and assemble. Furthermore, the present invention provides a blade mounting arrangement which can accommodate conventional saw blades of various constructions and which can hold the saw blade in place without the use of set screws and without the need to employ any other form of a tool. Still yet, the present invention provides a blade mounting arrangement having a design which protects its components from excessive wear and premature failure. The present invention also provides a saw blade ejection mechanism for ejecting the saw blade from the saw blade clamping arrangement.
The present invention provides a saw blade clamping arrangement for a power tool of the type including a housing, a drive shaft mounted for reciprocating motion relative to the housing, and a saw blade releasably interconnected with the drive shaft. The saw blade clamping arrangement includes a biasing member and an actuation member. The biasing member is interconnected to the drive shaft for exerting a biasing force to retain operative connection between the saw blade and the drive shaft. The actuation member is selectively moveable between a first position and a second position. The first position permits the biasing force of the biasing member to retain the operating connection between the saw blade and the drive shaft. The second position causes the actuation member to overcome the biasing force, thereby permitting removal of the saw blade from the drive shaft.
In one form, the present invention provides a power reciprocating saw having a gear case housing and a drive shaft mounted to the reciprocating saw for reciprocating motion relative to the gear case housing. A saw blade is releasably interconnected to the drive shaft for movement therewith. The power reciprocating saw further includes a clamping arrangement for mounting the saw blade to the drive shaft which includes a clamp support member, a spring clamp member and a release lever. The clamp support member is attached to the drive shaft for movement therewith. The spring clamp member is supported by the clamp support member and operates to retain the saw blade against the drive shaft. The release lever is pivotally attached to the housing for pivotal movement in a first direction about
Dassoulas Stephen C.
Derreth James J.
Grant Jeffrey P.
Melvin Jason R.
Moores, Jr. Robert G.
Black & Decker Inc.
Harness & Dickey & Pierce P.L.C.
Watts Douglas D.
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