Cutting – Interrelated tool actuating means and guard means
Reexamination Certificate
2000-04-26
2001-08-28
Rachuba, M. (Department: 3724)
Cutting
Interrelated tool actuating means and guard means
C083S478000, C083S490000
Reexamination Certificate
active
06279442
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a blade guard device, and more particularly to blade guard device for a circular sawing machine.
2. Description of the Related Art
The closest prior art of which the applicant is aware was disclosed in U.S. Pat. No. 5,203,245 to Terpstra, filed on Oct. 19, 1992, entitled “SWINGING BLADE GUARD ASSEMBLY”.
However, the blade guard assembly needs to additionally provide a slot
45
which co-operates with a slidable pin
47
for lifting a lower blade guard
25
, thereby increasing the parts of the blade guard assembly, and increasing the cost of fabrication. In addition, the stiffness and rigidity of the blade guard assembly are weakened due to provision of the slot
45
.
A conventional blade guard device for a circular sawing machine in accordance with the prior art shown in
FIG. 1
comprises an upper guard
1
, a lower guard
2
, a Y-link
3
, an elongated bent slot
4
, a circular mounting plate
5
, and a slide roller
6
. In operation, the slide roller
6
is moved with the upper guard
1
to press the Y-link
3
which pulls and rotates the circular mounting plate
5
by the bent slot
4
, thereby gradually rotating the lower guard
2
upward so that the circular sawing machine can be adapted to perform a safe sawing process. However, the gradual movement of the lower guard
2
makes the sawing process slow down, thereby greatly effecting the normal sawing operation of the circular sawing machine especially when it is used to saw a thick wood.
SUMMARY OF THE INVENTION
The present invention has arisen to mitigate and/or obviate the disadvantage of the conventional blade guard device for a circular sawing machine.
In accordance with one aspect of the present invention, there is provided a blade guard device for a circular sawing machine comprising: a support frame; a stationary base secured to the support frame; a locating plate secured to the stationary base; an upper guard having a lower end pivotally mounted on the stationary base and an upper end including a handle; a circular saw rotatably mounted on the upper guard; an elongated pressing lever having a first end pivotally mounted on the locating plate, and a mediate portion having a curved operation surface; a pressing roller secured on the upper guard to move therewith and slidably engaging the curved operation surface of the mediate portion of the pressing lever; a link having a first end secured to the second end of the pressing lever to move therewith; a circular mounting plate secured to a second end of the link to move therewith and rotatably mounted on the upper guard; and a lower guard secured to the circular mounting plate to rotate therewith for covering the circular saw.
The blade guard device further comprises a bolt extending through the second end of the pressing lever and through the first end of the link for securing the first end of the link to the second end of the pressing lever, and a bolt extending through the second end of the link and through the circular mounting plate for securing the second end of the link to the circular mounting plate.
The curved operation surface of the mediate portion of the pressing lever includes a projection extending outward and located proximate to the first end of the pressing lever, an inclined section extending inward from the projection, and a lower bent section extending from the inclined section and located proximate to the second end of the pressing lever.
By such an arrangement, when the handle is moved downward, the upper guard is pivoted downward to move the pressing roller which is initially moved to press the projection of the curved operation surface of the mediate portion of the pressing lever, thereby moving the link which largely pulls the circular mounting plate for rapidly rotating the circular mounting plate which rapidly rotates the lower guard upward, thereby rapidly exposing a lower part of the circular saw.
When the handle is further moved downward, the pressing roller is further moved to press the inclined section of the curved operation surface of the mediate portion of the pressing lever, thereby further moving the link which slightly pulls the circular mounting plate for gradually rotating the circular mounting plate which slowly rotates the lower guard upward, thereby slowly exposing the lower part of the circular saw.
When the handle is further moved downward, the pressing roller is further moved to press the lower bent section of the curved operation surface of the mediate portion of the pressing lever, thereby further moving the link which slightly pulls the circular mounting plate for gradually rotating the circular mounting plate which slowly rotates the lower guard upward, thereby slowly exposing the lower part of the circular saw.
Further benefits and advantages of the present invention will become apparent after a careful reading of the detailed description with appropriate reference to the accompanying drawings.
REFERENCES:
patent: 3998121 (1976-12-01), Bennett
patent: 4934233 (1990-06-01), Brundage et al.
patent: 5054352 (1991-10-01), Fushiya et al.
patent: 5203245 (1993-04-01), Terpstra
patent: 5257570 (1993-11-01), Shiotani et al.
patent: 5370025 (1994-12-01), Itzov
patent: 5609085 (1997-03-01), Chang
patent: 5724875 (1998-03-01), Meredith et al.
patent: 5752421 (1998-05-01), Chang
Connolly Bove & Lodge & Hutz LLP
Flores Sanchez Omar
Rachuba M.
LandOfFree
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