Cutting – By tool reciprocable along elongated edge
Reexamination Certificate
2001-01-29
2003-12-09
Payer, Hwei-Siu (Department: 3724)
Cutting
By tool reciprocable along elongated edge
C083S574000, C030S122000, C030S392000
Reexamination Certificate
active
06658979
ABSTRACT:
BACKGROUND OF THE INVENTION
The current invention is based on a hand-guided power jigsaw.
U.S. Pat. No. 5,027,518 has disclosed a power jigsaw of this generic type, which whose design corresponds to that of a hand-actuated jigsaw wherein the typically U-shaped frame has a handle protruding laterally downward, with a motor housing, wherein the back of the grip has a switch for controlling the energy supply of the motor.
In comparison to manual jigsaws, the known machine has the advantage that it is no longer necessary to execute the sawing motion by hand.
SUMMARY OF THE INVENTION
The power jigsaw according to the invention, has the advantage that it is very lightweight and handy and can be guided by the user in an especially well-controlled way.
The maneuvering reliability is improved by virtue of the fact that the pistol-like base housing adjoining the handle is elongated toward the rear and in the operating position, rests against the user's forearm.
Since the arms of the U-shaped frame are longer than the jigsaw blade by a multiple of its length, in particular twice as long as it, relatively large work pieces can be machined all the way to their centers with the jigsaw, i.e. in a board-like work piece, the maximal cutting depth from its edge is approx. 270 mm and is therefore relatively deep.
Since the switch button of the on/off switch of the motor is disposed between projections on the handle, this switch button can easily be operated, particularly with the index finger, and is simultaneously protected from unintentional actuation.
Since the base housing encapsulates the motor and drive means for moving the jigsaw blade back and forth, the motor and drive means are protected from dust and damage and the user is protected from being injured by the moving parts. The same advantage is achieved by virtue of the fact that on its free end, the upper arm of the frame has an end housing which contains the clamping means and drive means, for detachably clamping the jigsaw blade.
Since the jigsaw has a flat support surface, which is disposed on top of its base housing, is structured with parallel grooves, and is flush with the lower arm, the jigsaw can be guided in relation to the work piece in an especially well-controlled way with no lateral travel so that sawing can take place without deviation from lines laid out with a straightedge or compass.
Since the base housing of the jigsaw can be detachably coupled, particularly in detent fashion, to a sawing table, which can be fastened to a workbench for example, wherein the handle protrudes downward beyond the sawing table in an easy-to-grasp manner, the jigsaw with the sawing table attached to it can be used as a hand tool that can be positioned in a particularly precise manner or can be used as a stationary device when the sawing table is flange-mounted to a workbench.
Since the base housing of the power jigsaw can be coupled in a play-free fashion to the sawing table by means of longitudinal guides, in particular by means of discontinuous groove-and-spring guides, the power jigsaw can be inserted from above into the sawing table and connected to it in bayonet locking fashion without the use of an auxiliary tool.
Since the power jigsaw can be detached from the sawing table by pressing on an overlockable button, it can be detached from the sawing table in a particularly rapid and convenient manner without the use of an auxiliary tool.
Since the power jigsaw has a work piece depressor that can be moved parallel to the jigsaw blade and simultaneously functions as a finger deflector, the work piece to be machined is fixed in relation to the power jigsaw in a manner that can be controlled particularly well so that precise sawing can be done, wherein the user is protected against being injured by the oscillating saw blade.
Since the arms of the U-shaped frame have flat, free ends and each of these ends supports a leaf spring, the leaf springs are connected to the frame in a positionally secure manner with contact over their entire surface and are aligned parallel to one another so that they function as rockers for the parallelogram-like guidance of the saw blade and for producing a slight oscillating stroke.
Since the leaf springs have a central fork slot on their free ends, into each of which a clamping end of the jigsaw blade can be detachably suspended, it is possible to clamp the jigsaw blade in a positively engaging manner without tools in a manner that is more secure than the previously known frictionally engaging clamping of jigsaw blades through rotation of a wing nut.
Since the upper leaf spring is bent into a U-shape and is fastened, in particular riveted, with its lower leg to the free end of the arm of the U-shaped profile so that the legs point outward in the same direction as the free arm, wherein the curved part and the upper U-leg can be freely pivoted, this produces in a particularly inexpensive manner an elastically pre-stressed rocker for a parallelogram-like transmission for driving the jigsaw blade to oscillate, which solely produces the upward stroke of the jigsaw blade, wherein its counterpart rocker is the leaf spring fastened to the lower arm and its coupling is the jigsaw blade.
Since the lower leaf spring can be coupled to the motor, in particular in a positively engaging manner, via driving means, in particular via a connecting rod, the driving force is not transmitted directly onto the saw blade so that the movement reversal in the dead points on the movement path of the saw blade is damped.
Since the lower leaf spring, which is under no stress in the horizontal position, has a stamped, downwardly curved loop at its free end, which constitutes an eyelet for engaging the connecting rod, it is possible to produce a particularly inexpensive coupling between the connecting rod and the leaf spring.
Since the leaf springs, on their free ends, have a groove extending lateral to the slot, in which a nipple of the saw blade can be supported in a centered, pivotable fashion, in particular with its sharp edge, the jigsaw blade can be coupled to the oscillating leaf springs in a clamp-free, articulating fashion in the parallelogram-like mechanism.
Since the nipples are comprised of injection-molded plastic and have a square region pointing toward the saw blade, which passes through the fork slot in a play-free manner, the clamping ends of the jigsaw blade are reliably centered, are oscillation damped, and are electrically insulated in relation to the leaf springs.
Since the U-shaped frame is comprised of metal, in particular a tube with a circular or elliptical cross section, and the base housing and end housing are comprised of plastic, in particular of two housing shell halves that can be assembled, this power jigsaw enjoys a combination of lightweight construction, high stability of the support of the jigsaw blade and thereby ruggedness, ergonomic form, and a high degree of operational reliability.
REFERENCES:
patent: 2015275 (1935-09-01), Kelley
patent: 2753898 (1956-07-01), Macfarland
patent: 3117600 (1964-01-01), Davis
patent: 5027518 (1991-07-01), Adomatis
patent: 5176059 (1993-01-01), Anderson
patent: 5351590 (1994-10-01), Everts
patent: 5924209 (1999-07-01), Ward
patent: 6277135 (2001-08-01), Wang
patent: 6357123 (2002-03-01), Manuel
patent: 87 10 927 (1987-10-01), None
Engelfried Uwe
Frech Alfred
Keusch Siegfried
Lutz Tobias
Payer Hwei-Siu
Robert & Bosch GmbH
Striker Michael J.
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