Plastic article or earthenware shaping or treating: apparatus – With separate and distinct upstream agitating or kneading means – With cutting – severing or comminuting means
Reexamination Certificate
1998-11-04
2001-01-23
Pyon, Harold (Department: 1722)
Plastic article or earthenware shaping or treating: apparatus
With separate and distinct upstream agitating or kneading means
With cutting, severing or comminuting means
C425S205000, C100S097000, C100S215000
Reexamination Certificate
active
06176697
ABSTRACT:
FIELD OF THE INVENTION
This invention relates to a method and apparatus for the treatment of expanded and foamed plastic materials, for example, polystyrene, particularly to enable them to be recycled.
In U.S. Pat. No. 5,494,626, to which reference should be made, there is described and claimed a method for the treatment of expanded or foamed plastic material, said method comprising the following steps:
a) introducing the plastic material into a hopper which contains an auger having a cutting function,
b) operating the auger so as to cut the plastic material into pieces and to feed the pieces of plastic material into a chamber containing a first reciprocable piston movable in a first direction to effect compression of the pieces of plastic material and a second reciprocable piston movable in a second direction transverse to said first direction to effect further compression of the pieces of plastic material and to effect transfer of the compressed plastic material into the entry end of a chute containing a reciprocable main ram,
c) coordinating control of said first and second reciprocable pistons so that, while the main ram is in its non-advanced position, each of said first and second reciprocable pistons operates through a plurality of cycles to effect the transfer of a quantity of compressed plastic material into the entry end of the chute,
d) operating the main ram so that it advances along the chute to effect additional compression of the plastic material and displaces the plastic material towards the discharge end of the chute before returning to its original position, and
e) interrupting operation of the auger during such operation of the main ram.
Apparatus for use in carrying out said method is also described and claimed in U.S. Pat. No. 5,494,626.
The apparatus of U.S. Pat. No. 5,494,626 operates extremely efficiently when being used for the treatment of, for example, dry polystyrene and can effect compression of about 200 kg. of dry polystyrene per hour, achieving a volume reduction of about 47:1. If, however, the polystyrene is damp, the rate of production has to be reduced and, if the polystyrene is very wet, substantial problems are encountered.
It is accordingly an object of the present invention to provide an improved method and apparatus for the treatment of expanded or foamed plastic material. More particularly, it is an object of the present invention to provide a method and apparatus for the treatment of either wet or dry expanded or foamed plastic material.
SUMMARY OF THE INVENTION
According to a first aspect of the present invention there is provided a method for the treatment of expanded or foamed plastic material, said method comprising the following steps:
a) introducing the plastic material into a hopper which contains a first auger having a cutting function,
b) operating the first auger so as to cut the plastic material into pieces and to feed the pieces of plastic material into a first chamber containing a second auger,
c) operating the second auger so as to feed the pieces of plastic material into a second chamber and to effect a predetermined degree of compression of the plastic material in said second chamber, and
d) operating a hydraulic ram to compress the plastic material and to displace it from said second chamber into a friction chute along which the compressed plastic material is caused to travel as a result of successive operations of the hydraulic ram.
The first and second augers are preferably operated together until the achievement of the predetermined degree of compression of the plastic material is sensed. The second auger is preferably operated by means of an electric motor fitted with a current sensor unit, the arrangement being such that, when the auger motor current reaches a predetermined value, corresponding to said predetermined degree of compression of the plastic material, the sensor unit sends a signal to stop both augers, whereupon the hydraulic ram is caused to effect a forward and return stroke to compress the plastic material in said second chamber and displace it into the friction chute along which the compressed material is caused to travel.
The friction chute preferably has walls which, for a part at least of the length of the chute, can be urged towards one another to vary the pressure acting on the compressed plastic material as it is displaced along the chute. The optimum working pressure is preferably of the order of 220 to 240 bar.
The hydraulic pump which controls operation of the hydraulic ram preferably has characteristics such that the ram moves forwardly at a rate which is inversely proportional to the resistance which it encounters, i.e. the pressure which it needs to create to push the material out through the friction chute. This ensures that the plastic material is compacted with a smooth motion rather than with jerky movements which would cause stress on the machine.
The first auger is preferably arranged for rotation about a substantially horizontal axis and the second auger is preferably arranged for rotation about a substantially vertical axis, with the hopper in which the first auger is contained arranged above the friction chute through which the compressed material is discharged. The compressed material is preferably discharged along the chute in such manner that it can readily be broken into lengths for transport using standard pallets.
The friction chute is preferably vented to allow the escape of water and air from the compressed material as it is advanced along the chute.
According to a second aspect of the present invention there is provided apparatus for the treatment of expanded or foamed plastic material, said apparatus comprising:
a) a hopper into which the plastic material can be fed,
b) a first auger located within the hopper, said first auger having a cutting function,
c) a first chamber into which pieces of the plastic material are fed upon operation of the first auger,
d) a second auger contained within said first chamber,
e) a second chamber into which the pieces of plastic material are fed by the second auger, said second auger being arranged to effect a predetermined degree of compression of the plastic material fed into the second chamber,
f) a friction chute communicating with said second chamber,
g) a hydraulic ram arranged to compress the plastic material in the second chamber and to displace it from the second chamber into the friction chute, along which the compressed plastic material is caused to travel as a result of successive operations of the hydraulic ram, and
h) control means for controlling operation of the first and second augers and the hydraulic ram.
In the “rest” or inoperative condition of the apparatus, the ram is preferably in its advanced position. Thus, when the apparatus is switched on, a motor will be operated to drive a pump which controls operation of the hydraulic ram and both augers will be stopped.
As mentioned above, the first auger is preferably arranged for rotation about a horizontal axis and the second auger is preferably arranged for rotation about a vertical axis for effecting downward feeding and compression of the pieces of plastic material.
A sensor unit is preferably provided to detect the presence of foamed or expanded plastic material within the hopper. This sensor unit preferably comprises a light source and a photocell which generates a signal when the light beam is interrupted.
On generation of this signal, the hydraulic ram is preferably retracted and, once the ram reaches its retracted position, the vertical auger is started to feed any material in the first chamber into the second chamber. A short time after the vertical auger has commenced operation, the second auger starts operating and the two augers will then run together cutting the plastic material into pieces, feeding the cut pieces out of the hopper into the chamber containing the vertical auger and then feeding the pieces downwardly and compressing them in the ram chamber.
The power required to rotate the shaft of the vertical auger will depend on the resistance which it
Del Sole Joseph S.
Middleton Engineering Limited
Pyon Harold
Stoltz Melvin I.
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