Plastic article or earthenware shaping or treating: apparatus – Traversing roll pressurizing means operably associated with...
Reexamination Certificate
1999-04-16
2001-06-12
Pyon, Harold (Department: 1722)
Plastic article or earthenware shaping or treating: apparatus
Traversing roll pressurizing means operably associated with...
C425S333000, C425S38200R, C425SDIG002
Reexamination Certificate
active
06244850
ABSTRACT:
The application relates to a pelletizing press, comprising a drum with a drum axis, at least one press roller which is accommodated in the drum in such a way that it can rotate about a press roller axis, roller drive means for rotation of the press roller about the press roller axis, rotation means for rotation of the press roller and/or the drum about the drum axis, and roller adjustment means for varying the distance between the press roller axis and the drum axis.
A pelletizing press of the abovementioned type is known from EP-A-0,489,046, which discloses a pelletizing press in which a kneadable compound can be extruded as pellets by rotation of one or more rollers over an internal surface of a drum provided with holes. In this case the rollers rotate about the axis of the drum, and the material placed in the drum, such as, for example, animal feed, is kneaded and forced through the apertures in the drum wall. In order to obtain the optimum roller setting, which depends on internal friction, humidity and the material which is being pelletized, the rollers are also driven so that they rotate about their axis. Moreover, the distance between the rollers and the inside wall of the drum can be varied, in order to vary the gap width between the internal surface of the drum and the roller, and it is possible to rotate the drum also about the drum axis.
EP-B-0,238,147, in the name of Applicant, discloses a pelletizing press in which the axes of the rollers can be moved relative to the drum axis by means of a cam mechanism. For this purpose, a shaft extends along the drum axis from outside the drum into the pelletizing space. The shaft for driving the roller about the drum axis is formed by a second, hollow shaft which extends around the adjustment shaft and is mounted on bearings thereon.
An object of the present invention is to provide a pelletizing press in which the distance between the press roller and the internal drum surface can be varied efficiently during operation. Another object of the invention is to provide a pelletizing press in which the press roller and/or the drum are driven about the axis of the drum, and in which the rotation of the press roller about the press roller axis is independent of the speed of rotation of the press roller about the drum axis.
For this purpose, the pelletizing press according to the present invention is characterized in that the roller adjustment means comprise a first shaft situated along the drum axis, the roller drive means comprising a second shaft, situated concentrically around or inside the first shaft, and the rotation means comprising a third shaft, situated concentrically around or inside the first shaft.
By designing the adjustment means of the press roller, the roller drive means and the rotation means in the form of three concentric shafts, it is possible to obtain a very compact construction with a relatively simple design. With the three concentric shafts, the gap width between the press roller and the drum wall can be varied during rotation of the press roller about the press roller axis and rotation of the drum and/or the press roller about the drum axis. This means that there can be continuous adjustment of the gap width to, for example, the viscosity of the material to be pelletized, which viscosity changes during the pelletizing process.
The quality of the end product is influenced by adjusting the gap width. For example, a harder pellet with a smaller fine fraction can be obtained with a small size of gap.
The shaft of the roller adjustment means preferably forms the central shaft. The said shaft can be operated in the essentially stationary state and need only be rotated to a slight extent for adjustment of the axis of the press roll. The second shaft of the roller drive means is mounted on bearings on the shaft of the roller adjustment means, on which shaft in turn the third shaft of the rotation means for driving the drum and/or the press roller about the drum axis is placed.
The roller adjustment means preferably comprise a cam plate which acts upon a bearing housing of the press roller, which bearing housing acts by way of a spring element upon a supporting frame, the bearing housing being movable relative to the drum axis by rotation of the cam plate in the radial direction along the supporting frame.
By means of a resilient support of the press roller bearings, the distance from the axis of the roller can be varied relative to the drum axis using simple cam plates.
The shaft of the press roller is preferably connected to a first gear wheel, while the second shaft of the roller drive means comprises a second gear wheel. The gear wheels are situated at virtually the same position along the drum axis and are interconnected by a coupling with a length which is variable in the radial direction. Such a coupling can be formed by, for example, an elastic belt or toothed belt.
An embodiment of a pelletizing press according to the present invention will be described in greater detail with reference to the appended drawing. In the drawing:
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Nguyen Thukhanh T.
Pelleting Technology Nederland v.o.f.
Pyon Harold
Young & Thompson
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