Turning – Lathe – Portable
Reexamination Certificate
2000-08-18
2003-05-13
Tsai, Henry W. H. (Department: 3722)
Turning
Lathe
Portable
C082S152000, C030S390000, C451S354000
Reexamination Certificate
active
06561063
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to a protective guard for a hand-held rotary cut-off tool.
BACKGROUND OF THE INVENTION
A hand-held rotary cut-off tool has an abrasive rotary cut-off disk driven by an electric or pneumatic motor, and is used to cut a workpiece. The cut-off tool typically has a protective guard that partially surrounds the cut-off disk.
FIG. 1
shows a prior art pneumatic hand-held rotary cut-off tool
10
. The tool
10
has a housing
12
configured to be grasped by hand. The tool
10
also has an abrasive cut-off disk
14
attached to the end of an arbor
16
, concentrically aligned along a rotational axis
18
. A pneumatic motor
20
within a cavity
22
of the housing
12
rotates the arbor
16
and the cut-off disk
14
about the axis
18
. The tool
10
also has a half-bell shaped protective guard
24
. The guard
24
can swivel about the axis
18
as needed for adjustment but does not rotate with the disk
14
.
FIG. 2
shows an exploded view of major components of the cut-off tool
10
of FIG.
1
. The tool
10
has a nut
30
which serves to indirectly attach the guard
24
to the housing
12
. The nut
30
has a non-threaded nut bore
32
extending along the axis
18
entirely through the nut
30
. The nut
30
also has an external screw-thread
34
at one end, a torque structure
36
, having two flats
38
, at the other end, and a smooth nut shank portion
40
in-between. The nut shank portion
40
has a circumferentially-extending groove
42
. A nut abutment surface
44
is located between the external screw-thread
34
and the nut shank portion
40
.
The cut-off disk
14
is attached by a screw
46
to the arbor
16
. The arbor
16
passes through the nut bore
32
and is connected to and rotated by an output shaft
48
of the motor
20
. The nut
30
is screwed into the housing
12
.
The guard
24
has a flat guard flange
50
with a mounting hole
52
that receives the nut shank portion
40
. The guard flange
50
is held in place, on its axially-inner side, by a first flat washer
54
, a wave washer
56
and the nut abutment surface
44
. The guard flange
50
is held in place, on its axially-outer side, by a second flat washer
58
and a retaining ring
60
that snaps into the groove
42
. The wave washer
56
is compressively engaged by and between the nut abutment surface
44
and the flat washer
54
. Pressure from the wave washer
56
is transmitted through the flat washer
54
to the guard flange
50
and causes the guard
24
to be releasably restrained from swiveling about the nut shank portion
40
.
FIG. 3
shows an exploded view of major components of a second prior art cut-off tool
62
. The components and overall design of the second cut-off tool
62
are similar to those of the first cut-off tool
10
. The second prior art cut-off tool
62
has a nut
64
which serves the same function as the nut
30
of the first cut-off tool
10
. The nut
64
has a non-threaded nut bore
66
. The nut
64
also has an external screw-thread
70
at one end, a smooth nut shank portion
72
at the other end, and a torque structure
74
, having six flats
76
, in-between. The nut shank portion
72
has a retaining ring groove
78
. A nut abutment surface
80
is located between the torque structure
74
and the nut shank portion
72
. The second cut-off tool
62
also has a guard
82
similar to the guard
24
of the first cut-off tool
10
. A wave washer
84
is compressively engaged by and between the nut abutment surface
80
and a guard flange
86
.
Some differences between the first and second prior art cut-off tools
10
and
62
are as follows. The second prior art tool
62
lacks the flat washers
54
and
58
of the first prior art tool
10
. The shank portion
72
, the torque structure
74
and the abutment surface
80
of the nut
64
of the second prior art tool
62
are disposed in a different sequence than the corresponding features (the shank portion
40
, the torque structure
36
, and the abutment surface
44
) of the nut
30
of the first prior art tool
10
.
SUMMARY OF THE INVENTION
In accordance with the invention, a rotary cut-off tool has a hand-held housing. The housing has an open end centered on an axis, and has a housing abutment surface facing axially outward of the open end. A motor within the housing has an output shaft extending along the axis. A guard has a guard flange with a mounting hole. An arbor is configured to extend axially from the shaft through the mounting hole. The tool further has a spring and a cut-off disk receivable on the arbor. The spring has an installed position compressively engaged by and between the housing abutment surface and the guard flange, such that the spring releasably restrains the guard from swiveling about the axis.
In a preferred embodiment of the invention, the housing further has an internal screw-thread centered on the axis, and the tool further has a tubular fitting. The fitting has a bore that receives the arbor. An external screw-thread on the fitting is engageable with the internal screw-thread in the housing. The fitting further has an axially facing abutment surface, and a shank portion between the fitting abutment surface and the external screw-thread. When installed, the spring is received over the shank portion of the fitting.
REFERENCES:
patent: 4281457 (1981-08-01), Walton, II
patent: 4463636 (1984-08-01), Heller et al.
patent: 4993243 (1991-02-01), Guinn
patent: 5012582 (1991-05-01), Bristol et al.
patent: 5609516 (1997-03-01), Courson et al.
patent: 5784789 (1998-07-01), Vargas
patent: 5791979 (1998-08-01), Duncan et al.
patent: 6027399 (2000-02-01), Stewart
patent: 6048260 (2000-04-01), Kopras
patent: 6120362 (2000-09-01), Etter et al.
patent: 6149511 (2000-11-01), Huber
patent: 6389701 (2002-05-01), Friedland
Bass Gary S.
Mulford Ronald J.
Campbell Hausfeld/ Scott Fetzer Company
Jones Day
Tsai Henry W. H.
LandOfFree
Hand-held rotary cut-off tool does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Hand-held rotary cut-off tool, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Hand-held rotary cut-off tool will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-3050033