Measuring and testing – Vibration – By mechanical waves
Reexamination Certificate
1999-07-07
2001-02-06
Noori, Max (Department: 2855)
Measuring and testing
Vibration
By mechanical waves
C073S492000, C198S471100
Reexamination Certificate
active
06182511
ABSTRACT:
FIELD OF THE INVENTION
BACKGROUND OF THE INVENTION
The present invention relates generally to method and apparatus for inspecting bottles and, more particularly, to a method and apparatus for inspecting bottles which employs sound waves which rupture flawed bottles but which leave unflawed bottles undamaged.
FIG. 1
shows a conventional “convenience” bottle having a side wall
24
. The side wall
24
, as illustrated in
FIGS. 2 and 3
, has an exterior surface
42
and an interior surface
44
. The exterior surface
42
is typically somewhat rougher than the interior surface
44
. The interior surface may be made smoother by a bottle-forming technique known as “firepolishing” which increases the strength of the bottle.
FIG. 3
shows a fracture
46
in the exterior surface
42
of the bottle. A fracture
46
acts as a stress concentrater which significantly reduces the rupture strength of the bottle. The degree to which such a fracture
46
reduces the burst strength of the bottle varies with the depth of the fracture and the type of fracture. Table I illustrates data compiled by American Glass research showing the effect of different types of fractures on the breaking strength of soda lime glass bottles, the breaking load being indicated in pounds per square inch.
Long
ASTM
Bottle Surface
Time
1-
1-
Impact
Condition of Bottle
Load
20-min
minute
second
<1 ms
Pristine-Inside of
45000
63750
75000
100500
150000
Bottle Fire Polished
Pristine Molded
12000
17000
20000
26800
40000
Mild Abrasions
6000
8500
10000
13500
20000
Moderate Abrasion
2500
3400
4000
5400
8000
(produced by 320 Grit
sand paper)
Moderately Severe
2250
2850
3350
4500
5700
Abrasion (produced by
150 Grit sandpaper)
Severe Abrasion
1700
2125
2500
3350
5000
(produced by Diamond
Scratch)
Deep Bruises in Glass
650
1275
1500
2000
3000
Cracks in Glass
470
640
750
1000
1500
From the above table it may be seen that even very mild abrasions reduce the breaking strength of pristine-molded glass bottles (without inside fire polish) by 50% and that abrasions as small as 0.0005 inches in depth (150 grif sand paper) reduce the strength of pristine-molded glass bottles by 86%. It will also be appreciated that such small surface abrasions may be very difficult to detect by visual inspection. In addition to surface abrasions, there are a number of other types of flaws which reduce the breaking strength of a glass bottle including: score fractures, impact fractures, glass impurity fractures, stress concentrators due to improper melt temperature or improper cooling and stress concentrators caused by non-homogeneous compositions of glass and due to non-uniform glass distribution in the mold.
It is desirable for quality control purposes to test glass bottles after manufacture to determine whether flawed bottles are being created in the manufacturing process. The method for testing bottles most widely used in the industry today is known as a “squeeze tester”. U.S. Pat. No. 5,351,552 of Giometti, which is hereby incorporated by reference, discloses such a squeeze tester. Bottles to be tested are moved along a conveyor belt which supports each bottle at its base. The bottles move along a path extending between a static wall on one side and the wall of a large rotating wheel on the other side. A bottle moving along the path is squeezed between the static wall and the moving wall provided by the large wheel, rotating as it moves along this portion of the path. The large wheel is biased towards the static wall and applies a predetermined pressure to the side wall of a bottle as it rotates through this portion of the bottle path. The bottle squeezer thus applies a selected amount of pressure in a direction perpendicular to the side wall of the bottle. The amount of pressure applied is selected to be less than that required to break an unflawed bottle, but more than that required to break a flawed bottle. (“Flawed bottle” as used herein is a relative term, the severity of bottle fracture to be detected being decided by quality control personnel who set the loading of the bottle tester to a value slightly higher than the strength of a bottle having such a fracture.) A problem with bottle squeezers has been that shattering glass from a flawed bottle may become imbedded in the side wall of the rotating wheel of the squeezer. This embedded glass or “stone” may cause scoring of bottles passing through the squeezer resulting in the flawing of bottles which were originally undamaged. If the flaw is generated towards the end of the rotation of the bottle through the squeezer, it may not be exposed to the maximum pressure of the squeezer and thus may pass through the squeezer unruptured, even though it is now flawed and has reduced rupture strength. Also, due to the fact that the wheel of the squeezer has a very large circumference compared to the circumference of a bottle, many bottles may pass through the squeezer which do not come into contact with the glass fragment imbedded in the squeezer wheel. Thus, it may be difficult to detect whether an increase in the number of flawed bottles detected by the squeezer has been caused by glass embedded in the squeezer wheel or other outside causes such as defects in the mold, etc. Another problem with bottle squeezers is that they cannot be operated at more than about 300 bottles per minute.
The following patents also relate to bottle squeezers and are hereby specifically incorporated by reference for all that is disclosed therein: U.S. Pat. No. 3,702,563 issued Nov. 14, 1972 of Brady et al; U.S. Pat. No. 3,729,082 issued Apr. 24, 1973 of Federko; U.S. Pat. No. 3,765,231 issued Oct. 16, 1973 of Erb et al; U.S. Pat. No. 3,777,556 issued Dec. 11, 1973 of Zappia; U.S. Pat. No. 4,021,122 issued May 3, 1977; U.S. Pat. No. 4,077,254 issued Oct. 4, 1994 of Mercer, Jr. et al; U.S. Pat. No. 4,096,939 issued Jun. 27, 1978 of Riggs et al; and U.S. Pat. No. 4,479,582 issued Oct. 30, 1984 of Ducloux.
OBJECTS OF THE INVENTION
It is an object of the invention to provide a bottle testing method and apparatus which obviates problems experienced with bottle squeezer testers.
It is another object of the invention to provide a method and apparatus for testing bottles which enables rapid on-line testing of bottles.
It is another object of the invention to provide a method and apparatus for testing bottles which does not require contact with the bottle sidewall.
It is another object of the invention to provide a method and apparatus for testing bottles which does not cause bottle degradation.
It is another object of the invention to provide a method and apparatus for testing bottles which is quickly and easily adjusted to test different bottle configurations.
It is another object of the invention to provide a method and apparatus for testing bottles which is relatively inexpensive to implement.
SUMMARY OF THE INVENTION
The present invention is directed to a method and apparatus for testing bottles which overcomes the above-described problems of prior art testers. In one preferred embodiment, the invention may comprise a bottle testing apparatus for testing bottles for flaws of a predetermined magnitude, said bottles having a predetermined bottle configuration and having at least one natural frequency (also sometimes referred to as resonant frequency) comprising a sound system which produces sound of a character sufficient to rupture one of said bottles having a flaw of at least said predetermined magnitude but insufficient to rupture one of said bottles not having a flaw of at least said predetermined magnitude.
The invention may also comprise a bottle tester comprising a) at least one wave form generator tuned to at least one operating frequency which is about equal to a natural frequency of a bottle to be tested; b) at least one amplifier in electrical communication with said at least one wave form generator; and c) at least one acoustic transpo
Coors Brewing Company
Kelly Joseph J.
Klaas, Law, O'Meara & Malkin, P.C.
Noori Max
O'Meara William P.
LandOfFree
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