Conveyors: fluid current – Intake to fluid current conveyor – Upstream of suction source
Patent
1997-05-08
1998-08-11
Hoge, Gary C.
Conveyors: fluid current
Intake to fluid current conveyor
Upstream of suction source
406152, 406154, 406173, B05G 5324
Patent
active
057918309
DESCRIPTION:
BRIEF SUMMARY
FIELD OF INVENTION
This invention relates to a feed system for coarse particulate meltable material in the form of pellets, slats, minislats and the like, and in particular to a vacuum feed system for loose unmelted pieces of hot melt adhesives including a transition hopper to prevent premature melting of the loose pieces of material before they pass into a melt tank.
BACKGROUND OF THE INVENTION
Various types of vacuum or air pressure feed systems for particulate material are known in the prior art. Typical examples of such systems are shown and described in U.S. Pat. Nos. 4,299,683, (Adorno et al.), 4,532,860, (Simson), 4,344,723, (Ellingson), 4,583,885, (Thiele), and 4,569,293, (Evenson).
U.S. Pat. No. 5,006,019, (Dziedzic, Jr et al.) shows a specific design of a pneumatic pickup probe or wand for picking up a dry flowable material such as pelletized resin from a storage container and introducing that material into a vacuum conveyer system which transports it to a molding or extrusion press.
The term "particulate material" as used herein means coarse pieces of meltable stock material such as hot melt material. The pieces may be in the form of round pellets, or rectangular slats, for example of a size such as 1/4".times.11/2".times.21/2" or may be in other sizes or shapes.
A problem of premature melting is sometimes encountered in a vacuum conveyer or feed system when meltable pelletized or particulate material is transported through a feed system to a heated melt tank if the heat from the melt tank migrates into the feed system and causes certain portions of the feed system to reach or exceed the melting temperature of the material being conveyed to the melt tank. Such premature melting can cause sticking of release or outlet valves in the system or can cause bridging of the material when it reaches a temperature at which it melts or becomes tacky. The material can build up on interior walls of the feed system and ultimately close off the flow of materials to the melt tank. This is premature melting can be a serious problem in feed systems which feed melt tanks which may be heated to a temperature of as much as 232.degree. C., (450.degree. F.) when operating.
In addition to premature melting of the material being fed to the melt tank, vapors can rise from the melt tank and condense in the feed system causing blockage of the flow of material being fed.
OBJECTS OF THE INVENTION
In is an object of this invention to provide a transition hopper between a loader of pelletized meltable material and a melt tank for such material which reduces heat transfer from the melt tank to the loader.
Another object of the invention is to provide a transition hopper for a feed system for pelletized meltable material which is easy to install in a new system or to retrofit into an existing system.
A still further object of the invention is to provide a pressurized transition hopper for a feed system for conveying pelletized meltable material to a melt tank with a means of venting sticky hot melt condensate from the melt tank to prevent the condensate from entering the transition hopper.
Still another object of the invention is to provide a transition hopper for a feed system for pelletized hot melt materials which reduces sticking of valves in the system or build-up of material on the interior surfaces of the feed system equipment by reducing the heat transfer from a hot melt tank to the feed system.
An even further object of the invention is to permit a reduced distance between a feed system for particulate meltable materials and a melt tank without excessive heat transfer from the melt tank into to the feed system.
These and other objects of the invention will become more fully apparent in the following specification and the attached drawings.
SUMMARY OF THE INVENTION
This invention is a transition hopper for a feed system for conveying a particulate material from a storage container to a melt tank, where the system includes a loader having a means for withdrawing particulate material from the storage container, a
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Baker Lee R.
Dodge Dennis W.
Fort Wesley C.
Wujcik Chris D.
Hoge Gary C.
Milliken, Esq. Paul E.
Nordson Corporation
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