Cutlery – Cutting tools – Saw
Reexamination Certificate
2001-09-19
2003-09-30
Payer, Hwei-Siu (Department: 3724)
Cutlery
Cutting tools
Saw
C030S392000, C030S394000
Reexamination Certificate
active
06625892
ABSTRACT:
This application claims priority to Japanese application serial number 2000-283964, which application is hereby incorporated by reference herein in its entirety.
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to reciprocating cutting tools, such as jigsaws, that have a reciprocating saw blade for cutting workpieces.
2. Description of the Related Art
Known jigsaws comprise a rotating electric motor as a drive source and a motion conversion mechanism that converts the rotation of the motor into linear reciprocating movement of a blade. Japanese Laid-Open Utility Model Publication No. 4-54801 teaches a motion conversion mechanism for a jigsaw and this mechanism will now be described with reference to
FIG. 6
, which substantially corresponds to FIG. 1 from that Japanese publication.
As shown in
FIG. 6
, a jigsaw
100
includes a motion conversion mechanism
101
that has a crank disk
104
. The crank disk
104
is rotatably driven by an electric motor
102
via an intermediate gear
103
. A guide roller
105
is mounted on the crank disk
104
in a position displaced from the center of rotation of the crank disk
104
. Therefore, the guide roller
105
revolves around the rotational axis of the crank disk
104
, while the guide roller
105
also can rotate around its own axis. The guide roller
105
engages a horizontal engagement recess formed in a slider
107
that is fixed onto a vertical rod
106
. Therefore, as the crank disk
104
rotates, the guide roller
105
reciprocally moves along the horizontal recess of the slider
107
. Thus, the guide roller
105
imparts to the rod
106
a vertical reciprocating component of the rotating movement of crank disk
104
. However, the horizontal reciprocating component of the rotating movement of the crank disk
104
is not imparted to the rod
106
. Therefore, the rod
106
linearly reciprocates in the vertical direction with respect to the workpiece and the jigsaw
100
.
A rod holder
108
vertically slidably supports the rod
106
. An upper end of the rod holder
108
is connected to the body of the jigsaw
100
and can pivot about a horizontal axis by means of a pivot shaft
108
a
. A compression spring
109
serves to bias the lower portion of the rod holder
108
in a rearward direction, which direction is opposite to the moving direction (forward direction) of the jig saw
100
during the cutting operation.
A cam plate
110
is mounted on the intermediate gear
103
. A biasing roller
111
is coupled to the cam plate
110
, such that the biasing roller
111
reciprocates in the horizontal direction (forward and rearward directions) as the cam plate
110
rotates. Therefore, the blade B mounted on the lower end of the rod
106
is reciprocally pressed forwardly by the biasing roller
111
, as the cam plate
110
rotates. The biasing force of the biasing roller
111
counters or opposes the biasing force of the compression spring
109
.
According to this arrangement, because the rod holder
108
is pivotally supported by the pivot shaft
108
a
, the blade B may be prevented from twisting during the cutting operation and the blade B can reciprocally move both in the vertical direction and the forward and rearward directions. That is, the blade B can substantially move in an orbital path with respect to the workpiece and the jigsaw
100
.
However, problems exist with the design of the known jigsaw
100
. For example, because the slider
107
pivots forward and rearward together with the rod
106
, a clearance must be provided between the horizontal engagement recess of the slider
107
and the guide roller
105
in order to permit the slider
107
to incline relative to the guide roller
105
. Because of the presence of such a clearance, the guide roller
105
cannot move smoothly along the engagement recess of the slider
107
. Instead, the guide roller
105
will oscillate in the vertical direction between the upper and lower edges of the slider
107
. The motion conversion mechanism
101
will generate vibrations and sounds, due to the guide roller
105
repeatedly contacting and rattling between the edges of the slider
107
. Because these vibrations will be transmitted to the operator who is holding the jigsaw
100
while performing a cutting operation, the vibrations may fatigue the operator.
Another known motion conversion mechanism for a jigsaw is taught in U.S. Pat. No. 3,236,111. This conversion mechanism also utilizes a slider that engages a guide roller. Thus, the slider will reciprocate in the vertical direction as the guide roller revolves. However, a rod, on which a blade is mounted, is connected to the slider such that the rod can pivot relative to the slider in the forward and rearward directions. In addition, in order to reciprocate the rod (or the blade mounted on the rod) in the forward and rearward directions, the slider moves in the forward and rearward directions as the slide moves vertically. Therefore, during the cutting operation, the slider may receive a reaction force from a workpiece via the blade and the rod. As a result, the slider will pivot or incline relative to the guide roller and the guide roller will not smoothly move relative to the slider.
SUMMARY OF THE INVENTION
It is, accordingly, one object of the present invention to teach improved reciprocating cutting tools. For example, in one aspect of the present teachings, vibrations and noise may be reduced during the cutting operation.
According to one embodiment of the present teachings, a reciprocating cutting tool may include a slider that can reciprocate linearly in a first direction. A rod or blade shaft holder is movable with the slider in the first direction and is supported by the slider, such that the rod or blade shaft holder is movable in a second direction that is different from the first direction. A blade can be mounted on the rod (blade shaft holder) and the rod (blade shaft holder) is movable in the second direction independently of the movement of the slider in the first direction.
In a preferred embodiment, the first direction is a vertical direction with respect to a workpiece and the second direction is a horizontal direction (i.e., forward and rearward directions) of the workpiece. The blade may be moved in the forward direction to cut the workpiece during the cutting operation. Thus, the blade may substantially move along an orbital path with respect to the workpiece during the cutting operation.
Because the rod (blade shaft holder) is movable in the second direction independently of the movement of the slider in the first direction, the slider only moves in the first direction and preferably the slider does not move or incline in the second direction. Therefore, rattling is preferably reduced between the slider and a drive mechanism, which may be included within a motion conversion mechanism, because the motion conversion mechanism preferably does not move in the second direction. As a result, vibrations and noise that result from such rattling may be considerably reduced.
According to another embodiment of the present teachings, reciprocating cutting tools, such as a jig saw, may include a motor generating a rotational output, which rotational output is ultimately utilized to drive a blade in an orbital path with respect to a workpiece. A first means may be provided for converting the rotational output of the motor into linear reciprocating movement in a first plane. A second means also may be provided for transmitting the linear reciprocating movement to the blade. The second means may be, e.g., pivotally coupled to the first means and fixedly coupled to the blade. Preferably, the second means can reciprocate in the first plane and in a second plane that is substantially perpendicular to the first plane. Thus, the blade may preferably move an orbital path within the second plane. However, the first means preferably does not substantially move in the second plane.
In another embodiment, the first plane may comprise a vertical cutting direction with respect to the workpiece. Further, t
Inayoshi Hirotomo
Takahashi Yuji
Dennison, Schultz & Dougherty
Makita Corporation
Payer Hwei-Siu
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