GB2115722A

GB2115722A - A rollermill

Info

Publication number: GB2115722A
Application number: GB08303733A
Authority: GB
Inventors: Richard Fullalove; Paul Stevenson
Original assignee: Henry Simon Ltd
Current assignee: Henry Simon Ltd
Priority date: 1982-02-20
Filing date: 1983-02-10
Publication date: 1983-09-14
Also published as: GB8303733D0; GB2115722B

Abstract

A rollermill comprises a pair of grinding rolls arranged in close proximity to form a nip therebetween, the rolls being driven in opposite rotational directions at different speeds by drive means which includes a double-sided toothed belt (11) or a V-belt, wrapping appropriate different diameter complementary pulleys (13, 14) mounted on adjacent ends of the two grinding rolls and transmitting drive from one roll to the other. <IMAGE>

Description

SPECIFICATION A rollermill This invention concerns rollermills of the kind used for milling wheat, maize or other materials capable of being ground by such a machine.

As is well known, a rollermill essentially includes a pair of grinding rolls driven in opposite directions, one of which is driven at a slower speed than the other, the material to be milled being progressed through the nip between such rolls.

As is also known, means are usually provided to enable separation of the rolls, whilst they are being driven, in the absence of stock to be milled.

It is normal practice for the roll which is driven at the lower speed to be driven from the other roll by a suitable reduction drive system. It will be understood that when milling, there is a high torque in the drive system on account of the mechanical work being performed at the interface between the grinding rolls. Various kinds of drive system have been adopted. In one example, a primary drive motor is arranged to drive one of the rolls via a belt or chain, whilst the other roll is driven by means of a further driving connection between the first and second rolls, often at the opposite end of the rollermill from that at which the primary drive is established.In most known cases to transmit the drive from one roll to the other, a differential speed gearbox is used or alternatively a chain encased within an oil-sealed casing wherein the chain and sprockets run for lubrication in a bath of oil.

An object of the present invention is to provide a simplified driving system in a rollermill, wherein positive drive from one roll to another with the necessary speed differential between the two, is ensured.

According to the present invention there is provided a roilermill comprising a pair of grinding rolls arranged in close proximity to form a nip therebetween, the rolls being driven in opposite rotational directions with a speed differential between them thus to grind stock fed to the nip, characterised in that drive means for the rolls includes a flexible continuous driving member wrapping pulleys on both rolls at one end of the roll pair to transmit drive therebetween and capable of continuous operation substantially uniubricated.

Examples of the invention will now. be described, by way of example only, with reference to the accompanying schematic drawings illustrating the connection of a driving member or members between a primary drive motor and the grinding rolls of the rollermill.

Of the drawings: Fig. 1 shows schematically a system in which one continuous flexible driving member transmits the drive from a primary motor directly to both rolls; and Fig. 2 similarly illustrates a system in which a first driving member connects the primary drive motor to one of said rolls, and a secondary flexible continuous driving member serves to trans'mit the drive from said one roll to the other roll.

Referring now to the drawings, in the arrangement of Fig. 1 a toothed pulley 10 is mounted on the shaft of a primary drive motor (not shown). On one end of the rollermill, the pulley 10 is wrapped by a flexible double-sided toothed belt 11 which, via an adjustable idler pulley 12 wraps further toothed drive pulleys 1 3 and 14 on adjacent ends of the two grinding roll shafts (not shown) of the rollermill. As can be seen, by the arrangement in Fig. 1, pulleys 1 3 and 14 are driven in opposite directions, and since they are of different diameters, there is a speed differential between the grinding rolls connected thereto.

In the example illustrated, the axis of pulley 14 is movable between positions A and B which places the grinding rolls together or apart according to the presence or absence of stock to be milled. In this arrangement, movement of the pulley 1 4 between its two selected positions is permitted by movement of the rotational axis of idler pulley 12.

Pulleys 10, 12, 13 and 14 are toothed, with a curvilinear waveform and, as can be be seen in Fig. 1 there are co-operating teeth on both sides of belt 11, thus providing a positive and high-torque driving transmission from the primary drive motor to both grinding rolls. The curvilinear form of the teeth enables them to enter and leave corresponding grooves of similar shape in the pulleys, with a smooth, rolling motion ensuring minimum friction in mesh.

Referring now to Fig. 2 an arrangement is illustrated in which a primary drive motor (not shown) drives a pulley 10' which via a flexible drive member 1 5 drives a pulley 1 6 axially connected to one of the grinding rolls. The member 1 5 is preferably a V-belt but may be a belt having a flat or toothed configuration, or it may be a chain contained within an oil-sealed casing.

At the same, or the other, end of the rollermill, the grinding roll shaft carrying pulley 16, carries a further, co-axial pulley 13' which is toothed as are the pulleys in Fig. 1 , to receive one side of a double-sided toothed belt 17 of a similar construction to belt 11. Belt 17, via toothed idler pulleys 18 and 19, similarly wraps a toothed pulley 14' axially connected to the other grinding roll shaft. In this way, the toothed belt is again adapted to drive both grinding rolls in opposite directions at different speeds since pulleys 13' and 14' are of different diameters. Again, for movement of one grinding roll relative to the other idler pulley 18 or 19 is movable to take up slack in the belt 1 7 which nevertheiess is maintained under very low tension.

It will be readily appreciated that the provision of a simple toothed driving belt to provide positive driven connection between the rolls of a grinding mill, substantially alleviates the construction of the mill since no oil-sealed casings are required, and in operation the whole apparatus is rendered less noisy and more readily inspected and serviced.

It is not intended to limit the invention to the above examples only, many variations, such as might readily occur to one skilled in the art, being possible without departing from the scope of the invention.

For example, the toothed belt could in certain cases be replaced by a double-sided single or multiplex V-belt drive, provided sufficient frictional driving contact is ensured between the belt and the pulleys wrapped thereby; or alternatively by a chain of which the links can run over sprockets silently and without lubrication.

Claims

1. A rollermill comprising a pair of grinding rolls arranged in close proximity to form a nip therebetween, the rolls being driven in opposite rotational directions with a speed differential between them thus to grind stock fed to the nip, characterised in that drive means for the rolls includes a flexible continuous driving member wrapping pulleys on both rolls at one end of the roll pair to transmit drive therebetween and capable of continuous operation substantially unlubricated.

2. A rollermill according to Claim 1, including a pulley mounted for rotation on a primary drive motor and wrapped by said flexible continuous driving member which also wraps pulleys mounted on adjacent ends of the two grinding rolls to transmit drive from said primary motor to the grinding rolls to effect rotation thereof in opposite directions.

3. A rollermill according to Claim 1, wherein a pair of pulleys are mounted for rotation on adjacent ends of the two grinding rolls, one of said grinding rolls being driven in rotation by means other than said flexible continuous driving member and transmitting said drive via said flexible continuous driving member through said pulleys to the other grinding roll.

4. A rollermill according to any preceding claim, wherein said flexible continuous driving member is a toothed belt which is drivingly connected to the grinding rolls by means of toothed pulleys mounted on the rotational axes respectively thereof.

5. A rollermill according to Claim 1, wherein the teeth of said flexible continuous driving member are curvilinear and mesh with corresponding grooves of similar shape in a pair of pulleys mounted respectively on the rotational axes of said rolls, said pulleys being of different diameters thus to achieve said speed differential.

6. A rollermill according to any one of Claims 1 to 3, wherein said flexible continuous driving member is a double-sided V-belt.

7. A rollermill according to any preceding claim wherein said flexible continuous driving member wraps at least one idler pulley whose rotational axis is movable to permit separation of the grinding rolls.