Cutlery – Cutting tools – Saw
Reexamination Certificate
2002-02-27
2004-05-18
Watts, Douglas D. (Department: 3724)
Cutlery
Cutting tools
Saw
C279S078000, C030S339000
Reexamination Certificate
active
06735876
ABSTRACT:
This application claims priority to Japanese patent application serial numbers 2001-57158 and 2001-238392, the contents of which are hereby incorporated by reference.
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a blade clamping devices that can be utilized, e.g., with jigsaws and other reciprocating tools.
2. Description of the Related Art
A known blade clamping device for a jigsaw is taught in U.S. Pat. No. 5,306,025. This blade clamping device affixes a saw blade to a reciprocating drive shaft or plunger. The blade clamping device includes a centering sleeve that extends from the drive shaft and the centering sleeve includes an external threaded section. A clamping sleeve is rotatably mounted on the external threaded section of the centering sleeve. By rotating the clamping sleeve about the longitudinal axis of the drive shaft and the centering sleeve, the blade clamping device can be moved from a blade locking position (blade clamping position) to a blade replacement position. In the blade replacement position, the saw blade can be removed from the blade clamping device and a new saw blade can be inserted into the blade clamping device. The blade clamping device is then locked in the blade locking position by rotating the clamping sleeve back to the blade locking position. A torsion spring normally biases the clamping sleeve towards the blade locking position.
A connecting bush (collar) is rotatably mounted around the clamping sleeve. The connecting bush includes a gripping member (tab) that extends through an aperture defined in the jigsaw housing. The connecting bush is operably coupled to the clamping sleeve, such that rotating or pivoting the gripping member with respect to the jigsaw housing will cause the clamping sleeve to rotate. However, during a sawing operation, the connecting bush does not contact the clamping sleeve. Therefore, the blade clamping device can freely reciprocate together with the drive shaft without interference from the connecting bush. Further, the gripping member allows the operator to rotate or pivot the clamping sleeve to the blade replacement position without directly touching the clamping sleeve.
However, the clamping sleeve of U.S. Pat. No. 5,306,025 can rotate past the blade replacement position (i.e., the rotational range of the clamping sleeve is not restricted). Therefore, in order to remove the saw blade from the blade clamping device, the clamping sleeve must be accurately and precisely rotated to the blade replacement position, so that the saw blade receiving slots within the blade clamping device will properly align. If the clamping sleeve is not accurately and precisely positioned in the blade replacement position, the saw blade can not be easily removed from the blade clamping device, because the blade slots are not aligned, and thus, a saw blade can not be inserted into or removed from the blade clamping device.
In order to accurately define the blade replacement position, the aperture in the jigsaw housing is designed so that the gripping member of the connecting bush abuts an edge of the aperture when the clamping device reaches the blade replacement position. Thus, the aperture of the jigsaw housing is designed to limit the pivotal range of the clamping sleeve, so that the clamping sleeve will stop at the blade replacement position.
Consequently, the relative positional relationships of the clamping sleeve, the connection bush, the gripping member and the jigsaw housing aperture are critical for accurately determining the blade replacement position. If all of these structures are not accurately manufactured and/or accurately positioned during assembly, it may be difficult or impossible to accurately position the blade clamping device in the blade replacement position. Therefore, this known design suffers a significant drawback in being difficult to accurately and reliably design and manufacture.
SUMMARY OF THE INVENTION
It is, accordingly, one object of the present teachings to teach blade clamps or blade clamping devices that facilitate accurate and reliable positioning of the blade replacement position using relatively simple structures. Such blade clamps may be advantageously utilized with blades having positioning projections (or dogs) extending from respective sides of the blade, although the present teachings are not limited to such blades.
Thus, in one embodiment of the present teachings, jigsaws are taught as representative examples of reciprocating power tools that are particularly suited for the present blade clamps. Naturally, the present teachings are not limited to jigsaws and the present blade clamps can be advantageously utilized in a variety of applications and with a variety of tools.
Generally speaking, jigsaws may include a housing, a reciprocating drive shaft driven by a motor, a blade clamp and a saw blade. The drive shaft is also known in the art as a plunger or a spindle and such terms are interchangeable. In one embodiment of the present teachings, the blade clamp may include a tab that can be manually rotated or pivoted by the operator of the jigsaw. Further, the blade clamp may preferably include a stopper that accurately stops the blade clamp in the blade replacement position. Therefore, it is not necessary to utilize an aperture in the jigsaw housing as a means for accurately stopping the blade clamp in the blade replacement position. Instead, the stopper is preferably disposed internally within the blade clamp and thus, can more reliably and accurately position the blade clamp in the blade replacement position than known blade clamps. Consequently, the blade replacement position is not determined by the relative positional relationships of the tab or gripper member and the aperture of the power tool housing, thereby enabling the construction of more reliable blade clamping devices.
Optionally, the jigsaw may include an electric motor that serves as a drive source for the drive shaft. Further, a transmission optionally may be included to convert rotational movement of the drive source into substantially linear reciprocating movement of the drive shaft. A variety of drives sources and transmissions may be utilized with the present teachings and the present blade clamps are not limited to any particular drive source and/or transmission.
The present blade clamps may be affixed to a distal end of the drive shaft. Further, the present blade clamps may generally include a rod, a pushpin, and a rotatable sleeve. Further, a pivotable or rotatable collar may be disposed around the rotatable sleeve and preferably may be pivotally coupled to the housing. The collar may selectively engage the rotatable sleeve so as to rotate the blade clamp to the blade replacement position. The collar may preferably include a tab or other gripping member that permits the operator to manually manipulate the collar in order to rotate or pivot to the collar, and thereby pivot or rotate the blade clamp to the blade replacement position.
In one embodiment of the present teachings, the rod may be affixed to a lower or distal end of the drive shaft. A blade receiving portion (recess) may be defined within the rod. A base end of the blade may be inserted into the blade receiving portion so that the longitudinal axis of the blade is continuous, or substantially continuous, with the longitudinal axis (i.e., the reciprocating axis) of the drive shaft. The blade receiving portion may be arranged and constructed to as to be capable of receiving blades having a variety of different thickness. Further, a slot preferably extends from the blade receiving portion along the longitudinal axis of the rod. The slot is preferably designed to guide the blade into the blade receiving portion and to support the blade during operation.
In another embodiment of the present teachings, the rod may include an aperture that extends in a lateral direction of the rod (i.e., a direction perpendicular to the longitudinal or reciprocating axis of the rod). Further, the aperture preferably communicates with the rod slot
Birch & Stewart Kolasch & Birch, LLP
Makita Corporation
Watts Douglas D.
LandOfFree
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