Advancing material of indeterminate length – Plural material-moving means – With bight former
Patent
1980-03-31
1983-06-14
Christian, Leonard D.
Advancing material of indeterminate length
Plural material-moving means
With bight former
226 11, B65H 1742, B65H 2500
Patent
active
043878423
DESCRIPTION:
BRIEF SUMMARY
DESCRIPTION
1. Technical Field
This invention relates to machines which positively and variably feed material from bulk storage to downstream processing machinery.
2. Background Art
Many machines or machine processes utilize bulk material in the form of strips wound in a coil or stored in a container as a starting point for operations which result in a finished product. Such machinery is commonly used in conjunction with an apparatus which feeds material from its storage configuration into the downstream machine or machines. This feed apparatus must be capable of positively feeding material to downstream machinery, adapting to variable material requirements, and should not unduly stress the material as it is being fed.
Existing feed apparatus usually includes at least one set of two rollers which rotate in opposite directions and compress the material to be fed therebetween in order to provide a positive drive. After exiting these rollers, the material falls into a loop before entering subsequent machinery. The feed rate is controlled by means of a so-called mechanical "dancer" which consists of two or more limit switches positioned to intercept the material loop. Operation of these limit switches provides signals which control the operation of a drive motor connected to the rollers. On-off operation of the drive motor results in a relatively constant loop size and variable material feed.
This type of machinery has not proven entirely satisfactory since the rollers induce undesirable compression forces in the material, may subject the material to tension between pairs of rollers, and may cause material breakage if the material is momentarily not free to feed from storage. Also, such machinery is often unduly large and cumbersome and is relatively unsafe in that an operator, or the like, can come into contact with the moving material and, since it is tacky, it can catch the clothing or parts of the operator and pull the clothing and/or the operator into the machine.
The present invention is directed to overcoming one or more of the problems as set forth above.
DISCLOSURE OF INVENTION
The present invention provides a bulk material feed apparatus which is extremely compact in size, and, after initial start up, automatically begins feeding material whenever such material is necessary for the operation of downstream machinery, is capable of feeding material at a variable rate, induces only small compression or tension stresses in the material, varies material feed without contacting the material after it exits the drive rollers, and discontinues material feeding and sounds an alarm when the end of the stock is reached.
More particularly, in one aspect of the invention, material is looped over a primary drive roller, threaded behind and around a secondary roller mounted below and separated from the primary roller, and directed substantially horizontal to subsequent processing machinery. The secondary roller rotates slightly faster than the primary drive roller and roller separation is such that there is a relatively small contact arc length between the secondary roller and the material. This reduced contact allows the secondary roller to slip relative to the material and thus maintain a small amount of tension on the material in order to provide positive contact between the material and the primary roller.
Material feed rate is slightly higher than that which is necessary for the proper operation of downstream components, thereby causing the bulk material to fall into a loop between the feed apparatus and the subsequent machinery. A photoelectric detector senses the size of the loop and controls material feed rate by alternately starting and stopping the primary and secondary rollers. In this manner, a variable feed rate is achieved without contact between the feed apparatus and the material other than the drive rollers themselves.
In another aspect of the invention, a single drive roller is utilized which automatically provides variable material feed and feed start-up without the necessity of providing loop
REFERENCES:
patent: 2147467 (1939-02-01), Stephenson
patent: 3199803 (1965-10-01), Mattson
patent: 3228622 (1966-01-01), Colecchi
patent: 3721376 (1973-03-01), Christian et al.
patent: 4070951 (1978-01-01), Bala
Lytle, Sr. James R.
Stevens Samuel B.
Caterpillar Tractor Co.
Christian Leonard D.
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