GB2035883A

GB2035883A - Resiliently covered roller, of roller and ring extrusion pellitising press

Info

Publication number: GB2035883A
Application number: GB7937582A
Authority: GB
Original assignee: Simon Barron Ltd
Current assignee: Simon Barron Ltd
Priority date: 1978-11-02
Filing date: 1979-10-30
Publication date: 1980-06-25

Abstract

The annular die (1) of the press has extrusion bores therethrough, and is adapted to be rotated about its central axis, whereby material introduced within the die is extruded through the bores by one or more freely rotatable pelletising rollers (6) which each have a resilient plastics material peripheral shell (20) which engages with the inner peripheral surface of the annular die (1), each roller (6) being carried e.g. adjustably on a supporting structure connected to a stationary shaft (5), the die being fixed to a tubular rotor (2) which is rotatably mounted on the stationary shaft (5). In comparison with a hard steel roller, the shell (20) e.g. of non- foamed polyurethane, avoids wear of the die (1), is less costly, has less inertia, and is less susceptible to damage e.g. by an extrapped stone, and may wear less with some materials to be pelletised. <IMAGE>

Description

SPECIFICATION Improvements in or relating to pelletising machines This invention concerns a pelletising press of the kind (hereinafter termed of the kind referred to) comprising an annular die having bores therethrough which is adapted to be rotated about its central axis whereby material introduced into the centre of the die is extruded through said bores by the action of one or more freely rotatable pelletising rollers which engage with the inner peripheral surface of the annular die and which are carried on a support structure connected with a stationary shaft, the die being fixed to a tubular rotor which is rotatably mounted on said stationary shaft.

It has been usual for the pelletising rollers to be provided with outer peripheral shells of a very hard steel. Nonetheless wear of the rollers as well as the inner peripheral track of the annular die remains a problem necessitating maintenance and replacement at regular intervals.

The present invention is based upon an appreciation of the possibility of substantially reducing this wear by the use of pelletising rollers having peripheral shells of a resilient material.

According to the present invention there is provided a pelletising press of the kind referred to characterised in that the pelletising rollers have peripheral shells formed from a resilient plastics material.

The invention will be further apparent from the following description with reference to the figures of the accompanying drawings which show, by way of example only, in diagrammatic form, one kind of pelletising press embodying the invention.

Of the drawings: Figure 1 shows a partially sectioned plan view of the press; Figure 2 shows a front elevation of the press of Fig. 1; and Figure 3 shows a cross-section through one of the pelletising rollers of the press of Fig. 1 and on an enlarged scale.

Referring now to the drawings, it will be seen that the pelletising press, in known manner, consists of an annular die 1 which is secured to one end of a tubular rotor 2. The rotor 2 is mounted by bearings 3 and 4 on a normally stationary shaft 5 which carries a plate mounting a plurality of pelletising rollers 6 on shafts 26 whose centre lines are shown at 7.

The die 1 is provided with bores therethrough so that when it is rotated the pelletising rollers 6 serve to press material fed to the interior of the die through the bores, thus to pelletise it. In known manner, the normally stationary shaft 5 is prevented from rotation by means of a braking mechanism (not shown) but which can allow it to be carried with the die 1 in the event of jamming of the press as can happen if a stone or other hard object is introduced between one of the pelletising rollers 6 and the internal periphery of the die 1. Rotation of the normally stationary shaft in this manner actuates a switch to cut the supply of power to the drive.

Two drive motors 8 are provided which are preferably of substantially equal power. Each motor 8 drives a V-belt pulley 9. The V-belt pulleys 9 drive individual shafts 10 mounted in bearings 11 and 1 2 and carrying V-belt pulleys 1 3 at one of their ends and toothed belt pulleys 14 at their other ends. The drive between the pulleys 9 and 1 3 is transmitted by V-belts 1 5.

A toothed belt pulley 1 6 is secured to the rotor 2 and connected by an endless toothed belt 1 7 with the two toothed belt pulleys 14.

In accordance with the invention each of the pelletising rollers 6 is provided with an outer peripheral annular shell 20 which is formed from a resilient plastics material. The plastics material is preferably of non-foam polyurethane material and preferably one which is polyester based. Typically the material will have a hardness of shore 65D.

The shells 20 are preferably formed by injection moulding of the material and are secured by means of a suitable adhesive to a metal core 25 mounted for rotation on the shaft 26.

The shafts 26 are connected to the plate carried on the stationary shaft 5 in such a manner that the spacing between the periphery of the pelletising roll and the inner peripheral track of the annular die 1 can be adjusted.

The use of roll shells made from plastics material has a number of advantages. Firstly they are considerably cheaper than the conventional parts formed from hard steel, both in terms of the raw material and the manufacturing costs. Being lighter than steel the roll shells have less inertia and they are more durable in that they are less susceptible to damage in the event that a foreign body such as a stone or the like is introduced to the press with the feed. With certain kinds of feed the roll shells wear less rapidly than the conventional steel shells.

It will be appreciated that it is not intended to limit the invention to the above example only, many variations, such as might readily occur to one skilled in the art, being possible without departing from the scope thereof.

1. A pelletising press comprising an annular die having bores therethrough and adapted to be rotated about its central axis, at least one freely rotatable pelletising roller which engages with the inner peripheral surface of the annular die and which is carried on a

**WARNING** end of DESC field may overlap start of CLMS **.

Claims

**WARNING** start of CLMS field may overlap end of DESC **. SPECIFICATION Improvements in or relating to pelletising machines This invention concerns a pelletising press of the kind (hereinafter termed of the kind referred to) comprising an annular die having bores therethrough which is adapted to be rotated about its central axis whereby material introduced into the centre of the die is extruded through said bores by the action of one or more freely rotatable pelletising rollers which engage with the inner peripheral surface of the annular die and which are carried on a support structure connected with a stationary shaft, the die being fixed to a tubular rotor which is rotatably mounted on said stationary shaft. It has been usual for the pelletising rollers to be provided with outer peripheral shells of a very hard steel. Nonetheless wear of the rollers as well as the inner peripheral track of the annular die remains a problem necessitating maintenance and replacement at regular intervals. The present invention is based upon an appreciation of the possibility of substantially reducing this wear by the use of pelletising rollers having peripheral shells of a resilient material. According to the present invention there is provided a pelletising press of the kind referred to characterised in that the pelletising rollers have peripheral shells formed from a resilient plastics material. The invention will be further apparent from the following description with reference to the figures of the accompanying drawings which show, by way of example only, in diagrammatic form, one kind of pelletising press embodying the invention. Of the drawings: Figure 1 shows a partially sectioned plan view of the press; Figure 2 shows a front elevation of the press of Fig. 1; and Figure 3 shows a cross-section through one of the pelletising rollers of the press of Fig. 1 and on an enlarged scale. Referring now to the drawings, it will be seen that the pelletising press, in known manner, consists of an annular die 1 which is secured to one end of a tubular rotor 2. The rotor 2 is mounted by bearings 3 and 4 on a normally stationary shaft 5 which carries a plate mounting a plurality of pelletising rollers 6 on shafts 26 whose centre lines are shown at 7. The die 1 is provided with bores therethrough so that when it is rotated the pelletising rollers 6 serve to press material fed to the interior of the die through the bores, thus to pelletise it. In known manner, the normally stationary shaft 5 is prevented from rotation by means of a braking mechanism (not shown) but which can allow it to be carried with the die 1 in the event of jamming of the press as can happen if a stone or other hard object is introduced between one of the pelletising rollers 6 and the internal periphery of the die 1. Rotation of the normally stationary shaft in this manner actuates a switch to cut the supply of power to the drive. Two drive motors 8 are provided which are preferably of substantially equal power. Each motor 8 drives a V-belt pulley 9. The V-belt pulleys 9 drive individual shafts 10 mounted in bearings 11 and 1 2 and carrying V-belt pulleys 1 3 at one of their ends and toothed belt pulleys 14 at their other ends. The drive between the pulleys 9 and 1 3 is transmitted by V-belts 1 5. A toothed belt pulley 1 6 is secured to the rotor 2 and connected by an endless toothed belt 1 7 with the two toothed belt pulleys 14. In accordance with the invention each of the pelletising rollers 6 is provided with an outer peripheral annular shell 20 which is formed from a resilient plastics material. The plastics material is preferably of non-foam polyurethane material and preferably one which is polyester based. Typically the material will have a hardness of shore 65D. The shells 20 are preferably formed by injection moulding of the material and are secured by means of a suitable adhesive to a metal core 25 mounted for rotation on the shaft 26. The shafts 26 are connected to the plate carried on the stationary shaft 5 in such a manner that the spacing between the periphery of the pelletising roll and the inner peripheral track of the annular die 1 can be adjusted. The use of roll shells made from plastics material has a number of advantages. Firstly they are considerably cheaper than the conventional parts formed from hard steel, both in terms of the raw material and the manufacturing costs. Being lighter than steel the roll shells have less inertia and they are more durable in that they are less susceptible to damage in the event that a foreign body such as a stone or the like is introduced to the press with the feed. With certain kinds of feed the roll shells wear less rapidly than the conventional steel shells. It will be appreciated that it is not intended to limit the invention to the above example only, many variations, such as might readily occur to one skilled in the art, being possible without departing from the scope thereof. CLAIMS

1. A pelletising press comprising an annular die having bores therethrough and adapted to be rotated about its central axis, at least one freely rotatable pelletising roller which engages with the inner peripheral surface of the annular die and which is carried on a supporting structure connected with a stationary shaft, the die being fixed to-a tubular rotor which is rotatably mounted on said stationary shaft whereby material introduced into the centre of the die is extruded through the bores thereof by the inter-action of the surfaces of the die and the pelletising roller respectively, characterised in that the or each pelletising roller has a peripheral shell formed from a resilient plastics material.

2. A pelletising press according to claim 1, wherein a plurality of pelletising rollers are provided and freely rotatable on said supporting structure, each with its peripheral surface interacting with the internal peripheral surface of the die.

3. A pelletising press according to claim 1 or claim 2, wherein the peripheral shell of the or each pelletising roller is of a non-foamed polyurethane material.

4. A pelletising press according to any one of claims 1 to 3, wherein the or each said shell is of a material which is polyester based.

5. A pelletising press according to any one of claims 1 to 4, wherein the or each said shell is secured to a metal core mounted for rotation on said supporting structure such that the spacing between the periphery of the pelletising roll and the internal peripheral surface of the annular die can be adjusted.

6. A pelletising press, substantially as hereinbefore described with reference to and as illustrated in the accompanying drawings.