Classifying – separating – and assorting solids – Sifting – Elements
Reexamination Certificate
2000-05-31
2001-09-18
Walsh, Donald P. (Department: 3653)
Classifying, separating, and assorting solids
Sifting
Elements
C209S403000, C209S404000
Reexamination Certificate
active
06290069
ABSTRACT:
TECHNICAL FIELD OF THE INVENTION
The present invention relates generally to fasteners and in particular the present invention relates to a quick release tension fastener.
BACKGROUND OF THE INVENTION
Manufacturing industries, such as mining and food preparation, often employ sorting/sifting tables to separate material based on size. The sorting tables typically uses a series of screens that are attached to a vibration frame. The frame imparts vibration to the screens to sift material placed on the screens. The size of openings provided in the screens determines the size of the material that is sorted through the screens.
The screens are typically attached to the frame in a manner that allows for a tension to be maintained between the screens and the frame, without rigidly attaching the components. As illustrated in
FIG. 1
, one type of fastener
100
that can be used to couple a screen
110
to a frame
120
comprises a shaft
102
having a fastening end
104
that can be coupled to the screen. The fastener can be attached using a bolt
108
or similar feature, such as a hook provided on the screen. The shaft
102
passes through the frame
120
. A shoulder
112
can be provided on the shaft to contact the frame
120
. The shaft
102
also passes through a first washer
114
, a spring
116
and a second washer
118
. The opposite end
106
of the shaft is threaded to accept a nut
122
. The nut
122
is threaded onto the shaft
102
to compress the spring
116
. This type of fastener couples the screen
110
to the frame
120
and allows some relative movement of the screen and frame to be absorbed by the spring
116
. The screen can be removed by unthreading the nut and allowing the spring to expand. It will be appreciated that each screen uses multiple fasteners
100
on opposite sides of the screen.
The manufacturing environment in which the sorting equipment is operating can be excessively noisy. As such, the amount of time that employees are exposed to the high noise levels needs to be minimized. The above-described fastener requires that numerous nuts be un-threaded to remove or maintain a sorting screen. Other disadvantages of the prior threaded fastener include, bending or breaking the fastener shaft due to torque applied to the nut, and corrosion and dirt can prevent removal of the nut.
For the reasons stated above, and for other reasons stated below which will become apparent to those skilled in the art upon reading and understanding the present specification, there is a need in the art for a quick release tension fastener.
SUMMARY OF THE INVENTION
The above-mentioned problems with fasteners and other problems are addressed by the present invention and will be understood by reading and studying the following specification.
In one embodiment, a fastener comprises a coil spring, and a shaft having a first end and a second opposite end. The shaft passes through the coil spring. A quick release head is attached to the second end of the shaft. The quick release head comprises a moveable locking device that can be selectively engaged to maintain a compression force on the coil spring.
In another embodiment, a sifting machine comprises a sifting screen, a screen frame, and a plurality of tension fasteners coupled to the sifting screen and the screen frame. Each of the tension fasteners comprises a shaft having a first end attached to the sifting screen, a second opposite end, and a radially extending shoulder located between the first and second ends. The shaft extends through an opening in the screen frame such that the shoulder is located between the screen frame and the first end of the shaft. The tension fastener further comprises a coil spring having a central opening. The second end of the shaft passes through the central opening of the coil spring such that the coil spring is located between the second end and the screen frame. A quick release head is attached to the second end of the shaft. The quick release head comprises a moveable locking device that can be selectively moved to maintain a compression force on the coil spring.
REFERENCES:
patent: 5332101 (1994-07-01), Bakula
patent: 5598612 (1997-02-01), Sheldon
Hausladen Charles T.
Schwarze Joel R.
Beauchaine Mark J.
Fogg Slifer & Polglaze, PA
Technical Training Tools, Inc.
Walsh Donald P.
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