Abrading – Abrading process – Tumbling
Reexamination Certificate
2001-11-09
2004-10-26
Morgan, Eileen P. (Department: 3723)
Abrading
Abrading process
Tumbling
C451S035000, C451S038000, C451S326000
Reexamination Certificate
active
06808439
ABSTRACT:
FIELD OF THE INVENTION
This invention relates to an improved process and apparatus for finishing, and more specifically abrading, a large number of parts, substantially in bulk treatment, for removing flash, burrs, sharp corners and surface contamination.
BACKGROUND OF THE INVENTION
A wide variety of vibratory and tumbling processes and apparatus have been developed for finishing parts, and these known arrangements for the most part are reasonably efficient in their performance on some parts, particularly larger and more durable parts. The known arrangements, however, have proven less effective when dealing with large quantities of smaller parts and specifically those of more delicate materials such as plastics or powdered metals, and in particular those parts having complex configurations.
One of the most commonly used techniques for finishing parts involves a tumbling device such as an elongate barrel which rotates or moves generally about a horizontal axis, and the bulk quantity of parts is positioned in the barrel whereby they travel upwardly along one interior side of the barrel during rotation thereof, and then tumble back downwardly due to the effect of gravity. Tumblers of this type may be of a batch-type construction having a tumbling chamber in which a batch of parts is deposited, or may be of a flow-through construction having a generally spirally-shaped guide channel generated about the rotational axis so that the parts progressively move from an inlet end to an outlet end of the tumbler but the parts are otherwise treated in the same manner as in a batch-type tumbler. Many of these tumblers also use nozzles disposed interiorly thereof to effect blasting of the parts simultaneously with the tumbling thereof. These known arrangements, however, have been observed to be relatively violent in that the nature of the tumbling action makes it difficult to control the movement of the parts, and thus such arrangements have been observed to cause significant damage such as chipping and the like when the parts being processed are of a fragile or delicate nature. Such tumblers also are normally incapable of providing desired control over part movement since the nature of the overall movement of the bulk mass causes some parts to violently tumble downwardly along the top of the mass, whereas other parts slide backward at the bottom of the mass and hence are not properly exposed to the blasting spray.
Similar known tumbling devices involve angled moving belts which cause the bulk mass to move in a manner similar to a rotating barrel device and hence possess similar limitations.
With respect to known vibratory arrangements, the parts are typically positioned in a vibratory machine having an elongate and typically annular channel which contains not only the parts, but also a quantity of bulk abrasive media together with water or other liquid. Due to the vibration of the machine, the parts and bulk abrasive media function effectively as a flowable mass such that the parts and abrasive media are moved, typically in a progressive screw-like pattern along the length of the confining chamber as a result of the vibration of the apparatus. The gradual tumbling movement of the flowable mass causes the parts and abrasive media to continually rub and contact one another so as to effect surface finishing of the parts. While such vibratory arrangement is particularly desirable in that it is capable of handling and not severely damaging delicate parts, nevertheless such process is relatively slow in terms of performance time, is typically a wet process which requires additional secondary operations such as drying, and also requires substantial quantities of consumable abrasive media. This arrangement also is not as effective for finishing of complex shaped parts, specifically those having bores or holes therethrough due to the difficulty in effectively accessing such regions during tumbling of the flowable mass.
When utilizing tumblers for effecting blasting of parts as briefly described above, typical operation of the process normally results in overblasting of the batch of parts in order to effect blasting of all parts in the batch, which overblasting is required due to the nonuniformity of the blasting process and which results in some parts being excessively treated. This also results in the overall blasting process being of reduced efficiency due to the extended blasting time involved and the greater use requirements of abrasives.
With many prior processes and apparatus, particularly when surface finishing parts having complex contours and/or internal cavities, it has been necessary to physically individually fixture the parts in order to permit the parts to be acted on by appropriate tooling or blasting nozzles so as to permit surface treating of the complex part surfaces and specifically the interior cavity walls. The need to individually fixture and treat parts is obviously a very inefficient and time consuming process, but is a process which is frequently resorted to in view of the inability to effectively surface treat such parts using other known techniques.
Accordingly, it is an object of this invention to provide an improved process and apparatus for finishing, for example abrading, parts which particularly have a complex configuration or shape, and/or which may be of delicate or frangible material, with the improved process and apparatus of this invention overcoming many of the disadvantages associated with prior arrangements.
It is a further object of the invention to provide an improved process for finishing bulk parts by a continuous process which enables the parts to slowly move, as with a tumbling movement along a spiral path having closely adjacent convolutions, through a treating zone created by a blasting nozzle to permit a first-in first-out operation.
It is a still further object to provide a process, as aforesaid, which utilizes a vibratory device containing a narrow but elongate treating channel combined with a blasting nozzle which sprays, at high velocity, a preferably dry abrasive spray into the moving bulk mass in the channel to effect surface treating of the moving tumbling parts as they move through the spray zone.
More specifically, this invention relates to a process and apparatus wherein a bulk quantity of parts are positioned in a channel-like treating chamber which is subjected to vibration so as to cause the flowable mass of parts in the chamber to slowly undergo a corkscrew-like tumbling movement, whereby the parts are slowly and gently circumferentially tumbled around the transverse cross-section of the treating chamber while at the same time the flowable mass of parts is progressively moved lengthwise of the chamber. In a preferred embodiment, one or more nozzle arrangements are positioned directly over the treating chamber so that each nozzle has its discharge orifice position closely adjacent and directly above the flowing bulk mass in the chamber so as to effect a high-pressure blasting of a selected region of the flowing mass. The nozzle emits a downwardly-directed high-velocity spray which is defined by a carrier medium such as air having small abrasive particles or grit embedded therein. The abrasive spray contacts a reasonably small or concentrated area which has relatively small transverse and longitudinal extent over the flowing mass in the chamber. Due to its high-velocity discharge, the spray is effective in penetrating downwardly at least partway into the depth of the flowing mass. Accordingly, the slow corkscrew-like vibratory movement of the tumbling bulk mass causes and allows the orientation of the individual parts making up the mass to constantly change as they slowly move through the relatively small blasting zone defined below the nozzle, whereby the many different surfaces including edges and corners of the parts are thus subjected to the high-velocity abrasive spray which is effective for removing flash, burrs, sharp edges, surface oxides and the like.
In the improved process and apparatus of the present invention, as aforesaid, th
Flynn ,Thiel, Boutell & Tanis, P.C.
Morgan Eileen P.
Roto-Finish Company, Inc.
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