GB2233249A - Roller mill - Google Patents

Abstract

A roller mill comprises a pair of rolls 3, 4 mounted such that the rolling surfaces thereof are in close proximity to each other at a nip point. At least one of the rolls 4 is mounted such that the axis of rotation thereof is movable about a second axis whereby the roll may be moved towards and away from the other roll 3. A biassing means 17 biasses the rotation of the axis of rotation of the roll about the second axis to urge the roll toward the other. The pair of rolls is mounted between a pair of rigid side support members 1, and a cheek plate 23 on each side of the rolls is arranged to prevent lateral movement of the cereal to be milled beyond the ends of the rolls. Each cheek plate is mounted on the side panel of the mill, the panel being flexible and caused to flex towards and away from the rolls by means of an adjustment member 27 bearing against the cheek plate or the side panel, the adjustment member being displaceably mounted in the side support member 1. A manually operated spring biassed feed control may be provided (Figs 5a & 5b, not shown). <IMAGE>

Description

Roller Mill This invention relates to a roller mill, suitable for example for crushing grain to flakes for use as animal feed.

Conventional roller mills comprise a pair of rolls mounted in a rigid frame, one roll being driven, e.g. by an electric motor, and the other being freely rotatable and caused to rotate by contact with the driven roll via the material being milled passing between the rolls. One of the rolls, typically the freely rotatable roll, is mounted with its axis of rotation slidable relative to the frame. A spring biasses the roll towards an adjustable stop, which is used to set the gap between the rolls, or presses one roll directly on to-the other, and serves to provide the crushing force, as well as to permit the rolls to separate if, for example, a foreign body such as a stone is accidentally fed to the roll gap. Typically, the adjustment of the spring force is by a screw arrangement.

The present invention provides, according to one aspect, a roller mill, comprising a pair of rolls mounted such that the rolling surfaces thereof are in close proximity to each other at a nip point, at least one of the rolls being mounted such that the axis of rotation thereof is movable about a second axis whereby the said one of the rolls may be moved towards and away from the other roll, and biassing means biassing the rotation of the axis of rotation of the roll about the second axis, whereby the roll is urged towards the other roll.

Preferably, the amount of bias applied to the rotation of the axis of rotation of the roll about the second axis by the biassing means is adjustable. This may be coarse adjustment, whereby the roll may be moved into and out of said predetermined position, or fine adjustment, whereby the distance between the rolling surfaces of the rolls at the nip point may be varied when the roll is in the predetermined position, or both.

The biassing means may comprise a spiral spring, and the coarse adjustment may be achieved by moving the outer end of the spiral spring to rotate the axis of rotation of the roll about the second axis, while the fine adjustment may be performed by an adjustment member, such as a screw passing through a fixed mounting and bearing against the inner end of the spiral spring.

One problem in the construction of conventional roll mills of this type is the need to contain the material being milled between the rolls, preventing losses at the ends of the rolls. This may be achieved by "cheek plates", which are positioned at the sides of the rolls. It is essential that these cheek plates should not touch the rolls, since wear would occur, but they must be sufficiently close to prevent escape of the material to be milled.

Accordingly, another aspect of the invention provides a roller mill, comprising a pair of rolls mounted between a pair of rigid side support members such that the rolling surfaces of the rolls are in close proximity to each other at a nip point, and a cheek plate on each side of the rolls, arranged to prevent lateral movement of the material to be milled beyond the ends of the rolls, each cheek plate being mounted on a mounting member which can be caused to flex towards and away from the rolls by means of an adjustment member bearing against the cheek plate or said mounting member, the adjustment member being displaceably mounted in the side support member.

By using the flexibility of the members mounting the cheek plates to achieve adjustment, precise control of the spacing can be achieved very simply. The cheek plates may be formed from mild steel sheet, for example.

The mill of the invention may readily be used for milling a wide variety of materials, and is particularly suited to the crushing of cereals.

Reference is made to the drawings, in which: Figure 1A is a diagrammatic side elevation of a mill in accordance with the invention; Figure 1B is a corresponding view with the side of the mill removed to show the rolls and the cheek plate; Figure 1C is the same view, but with the cheek plate removed to show the feed arrangements; Figures 2A, 2B and 2C are simplified diagrams showing the adjustment of the positions of the rolls; Figure 3 is a partial sectional view on line A-A of Figure 1A showing adjustment of the cheek plates; Figure 4 is a partial sectional view on line B-B of Figure lA; Figures 5A and 5B are enlarged detail views of the input control arrangement shown in Figure 1C; and Figure 6 is an enlarged detail view of the bottom scraper arrangement shown in Figures 1B and 1C.

Referring to Figures 1A to lC, the mill comprises a pair of rigid steel side bars 1 linked together at each end by rigid steel rods 2 to form a rigid frame. Two rolls 3 and 4 are rotatably mounted between the side bars with their axles 5 and 6 parallel. The frame is mounted in a casing 7 fabricated from steel sheet. This arrangement ensures that the rolls 3 and 4 are mounted with sufficient precision, while providing a general framework for the mill which is cheap and simple to fabricate, requiring relatively low precision fabrication techniques.

One roll 3 has its axle 5 mounted in a fixed position and is provided with a sprocket wheel 8. An electric motor 9 is mounted on a bracket 10, which is pivotally mounted on one side bar 1 and has a slot 11 through which passes a screw 12 to permit the bracket to clamped in a selected position of adjustment relative to the sprocket wheel 8.

The motor 9 carries a sprocket wheel 13 and drives the roll 3 via a chain 14 whose tension is adjusted by pivoting and clamping of the bracket 10. It will readily be appreciated that other drive transmission means may be used, for example drive belts and pulleys, especially toothed belts.

The other roll 4 is freely rotatably mounted on its spindle 6, which is in turn pivoted eccentrically between the side bars 1. A spiral steel spring 17 is attached by its inner end 17a to the spindle 6, such that rotation of the spring 17 rotates the spindle, while its outer end 17b is pivotally attached to a pull rod 18 which is in turn pivotally attached to a lever 19 such that the end of the spring may be moved between a first position, represented by chain-dotted lines in Figure IA, in which the roll 4 is in its inoperative position, as will be explained hereinafter with reference to Figure 2, and a second position, represented in Figure 1A by the solid lines, in which the roll 4 is in its operative position. The inner end 17a of the spiral spring 17 projecting beyond the spindle 6 is engaged by a screw 20 held in a threaded bore in an abutment 21 extending from the side bar 1. In an alternative arrangement, the screw 20 is threadedly mounted in the inner end 17a of the spiral spring and bears against the fixed abutment 21.

The adjustment of the position of the roll 4 relative to the roll. 3 will be more readily understood by reference to Figures 2A to 2C. In Figure 2A the spring 17 is shown in its operative position with a biassing force being applied to the outer end 17b thereof in the direction of the arrow A. This force is transmitted to the spindle 6, tending to cause it to rotate in an anti-clockwise direction, thereby tending to urge the centre of rotation of the roll 4 towards the roll 3, and thus pressing the rolls together. In practice, the presence of a stop member constituted by the screw 20 located in the abutment 21, as shown in Figures 1A and 2C, would normally prevent the rolls from contacting one another, although the rolls can be arranged to run in contact with one another, if required.

In Figure 2B, the free end of the spring 17 has been rotated clockwise, thereby rotating the spindle 6 clockwise to cause the axis of rotation of the roll 4 to move away from the roll 3, thus separating the rolls.

Figure 2C shows the effect of the screw 20 in setting the gap between the rolls. Screwing the screw 20 downwardly urges the inner end 17a of the spring 17 downwards, rotating the spindle clockwise and thereby causing the rolls 3 and 4 to separate by the desired amount. When the spring is tensioned, as described with reference to Figure 2A, the action of the screw 20 is to limit the anti-clockwise rotation of the spindle so that further force on the outer end 17b of the spring 17 biasses the inner end against the screw 20. The gap is selected so that sufficient crushing of the material is obtained, while the gap is sufficient to ensure that the material enters the gap sufficiently to be engaged by the rolls and drawn through the gap. The force applied to the end 17b of the spring is selected to ensure that the required crushing action is applied to the material to be milled.The force is adjusted by varying the length of the pull rod 18, for example by a screw adjustment.

Referring again to Figure 1B, the casing 7 includes in its upper part a feed chute 22 and rigid cheek plates 23, which are attached to the sheet metal side panels of the mill, and which serve to prevent loss of the material to be milled from the ends of the rolls 3 and 4. Figures 3 and 4 illustrate the adjustment of these cheek plates 23 relative to the rolls 3 and 4 to ensure that the gaps between the rolls and the cheek plates are kept to a minimum compatible with the free rotation of the rolls. At their upper parts, the cheek plates are linked in the space between the rolls by a tie rod 24 passing through a hole in each cheek plate 23, and its attached side panel, and having threaded ends on to each of which are threaded a pair of nuts 25 and 26, which sandwich the respective cheek plate therebetween.The positions of the cheek plates are adjusted by screwing the nuts 25 and 26 inwardly or outwardly to flex the attached panel.

At the lower part of the cheek plates adjacent the nip between the rolls, grub screws 27 pass through threaded holes in the side bars 1 and engage the cheek plates. Screwing the grub screws inwardly again causes the side panels to which the cheek plates are attached to flex inwardly, thereby closing the gap between the cheek plates and the rolls. As may be seen from Figure 4, the cheek plates are also held against thrust pads 28, for example of a plastics material, located between the side bars 1 and the rolls, by means of further grub screws 29 which serve to centralise the rolls and to reduce side movement thereof to a minimum.

Flow of the material to be milled from the feed chute 22 to the nip between the rolls is controlled by a control flap 30 (Figure 1C), which is pivotable in a manner hereinafter described with reference to Figure 5 by a control rod 31 having an adjustable end stop 32 which can be engaged in latch 33 to hold the control flap 30 open, or released therefrom to close the control flap and prevent further material from flowing to the nip. This control can also be extended by means of a control cable to a remote location from which the feeding of material to the rolls can be controlled. This is particularly of use where the mill is mounted over the entry to a feed hopper or the like.

Referring to Figure 5, the control flap 30 consists of a metal plate bent to form an obtuse angle between the two parts thereof. A minor part 30a forms a lever to which the control rod 31 is connected. The control flap is connected to a mounting 34, set at an appropriate angle, by a bolt 35 which passes freely through an aperture in the flap 30 and through an aperture in the mounting 34. A nut 36 retains a helical spring 37 between itself and the mounting 34 to bias the flap 30 into contact with the mounting 34, in which position the free end of the flap 30 is in very close proximity to the surface of the roll 3, thereby preventing flow of the material. Figure SA shows the control flap in its closed position, in which it prevents flow of material to the nip point, and Figure 5B shows the control flap after it has pivoted upwardly to its open position.

Scrapers 38 are mounted beneath the rolls 3 and 4 and engage their surfaces to remove any material adhering to them. As may be seen from Figure 6, the scrapers consist of metal plates 39 each having a central mounting hole 40 therethrough adjacent the lower edge thereof. A mounting bolt 41 passes through the hole 40 and is screwed into a threaded hole 42 in a respective square or other non-circular section bar 43 which rests between correspondingly-shaped apertures in the sides of the casing 7, the apertures serving to prevent rotation of the bar. A nut 44 locks each bolt in place, and a helical spring 45 extends under compression between the plate 39 and the bar 43. The spring 45 serves to urge the plate 39 into engagement with the surface of the respective roll. The spring 45, because of the angle it makes with the plate 39, applies a greater force to the plate below the hole 40 than above it, thereby tending to rotate the plate into contact with the roll. The force applied can be adjusted by screwing the bolt inwardly or outwardly to increase or decrease the compression of the spring. The single hole mounting of each plate 39 permits the plates to align themselves with the surface of the rolls.

Claims (11)

Claims

1. A roller mill, comprising a pair of rolls mounted such that the rolling surfaces thereof are in close proximity to each other at a nip point, at least one of the rolls being mounted such that the axis of rotation thereof is movable about a second axis whereby the said one of the rolls may be moved towards and away from the other roll, and biassing means biassing the rotation of the axis of rotation of the roll about the second axis, whereby the roll is urged towards the other roll.

2. A roller mill according to Claim 1, wherein the amount of bias applied to the rotation of the axis of rotation of the roll about the second axis by the biassing means is adjustable.

3. A roller mill according to Claim 2, wherein the biassing means is arranged to permit coarse adjustment, whereby the biassing force urging the roll towards the other roll may be varied.

4. A roller mill according to Claim 2 or 3, wherein the biassing means is arranged to permit fine adjustment, whereby the distance between the rolling surfaces of the rolls at the nip point may be varied when the roll is in the predetermined position.

5. A roller mill according to any preceding claim, wherein the biassing means may be adjusted to remove the biassing force from the said roll and to cause the roll to move away from the other roll, thereby permitting access to the rolls at the nip point.

6. A roller mill according to Claim 3, 4 or 5, wherein the biassing means comprises a spiral spring.

7. A roller mill according to Claim 6, wherein the outer end of the spiral spring is movable about the second axis to permit coarse adjustment.

8. A roller mill according to Claim 6 or 7, wherein the inner end of the spiral spring bears against an adjustment member movable to permit the fine adjustment.

9. A roller mill according to any preceding claim, wherein the rolls are mounted in a rigid supporting frame, the frame being supported by a casing for the mill.

10. A roller mill according to Claim 9, wherein the casing is formed from sheet metal.

11. A roller mill, substantially as described with reference to, or as shown in, the drawings.

11. A roller mill, comprising a pair of rolls mounted between a pair of rigid side support members such that the rolling surfaces of the rolls are in close proximity to each other at a nip point, and a cheek plate on each side of the rolls, arranged to prevent lateral movement of the material to be milled beyond the ends of the rolls, each cheek plate being mounted on a mounting member which can be caused to flex towards and away from the rolls by means of an adjustment member bearing against the cheek plate or said mounting member, the adjustment member being displaceably mounted in the side support member.

12. A roller mill according to Claim 11, wherein each adjustment member is a screw mounted in a threaded hole in one of the side support members.

13. A roller mill according to Claim 11 or 12, wherein the mounting member is a body panel forming a part of the body of the mill.

14. A roller mill, substantially as described with reference to, or as shown in, the drawings.

Amendments to the claims have been filed as follows

1. A roller mill, comprising a pair of rolls mounted such that the rolling surfaces thereof are in close proximity to each other at a nip point, at least one of the rolls being freely rotatable on a spindle which is mounted eccentrically such that the axis of rotation of the spindle is movable around the eccentric axis whereby the said one of the rolls may be moved towards and away from the other roll, and biassing means biassing the rotation of the axis of rotation of the roll about the second axis, whereby the roll is urged towards the other roll.

2. A roller mill according to Claim 1, wherein the biassing means comprises a spiral spring, the outer end of which is movable about the second axis to permit coarse adjustment of the bias applied to the rotation of the axis of rotation of the roll about the second axis whereby the biassing force urging the roll towards the other roll may be varied.

3. A roller mill according to Claim 1 or 2, wherein the biassing means is arranged to permit fine adjustment, whereby the distance between the rolling surfaces of the rolls at the nip point may be varied when the roll is in the predetermined position.

4. A roller mill according to Claim 1, 2 or 3, wherein the biassing means may be adjusted to remove the biassing force from the said roll and to cause the roll to move away from the other roll, thereby permitting access to the rolls at the nip point.

5. A roller mill according to Claim 3, wherein the biassing means is a spiral spring, the inner end of the which bears against an adjustment member movable to permit the fine adjustment.

6. A roller mill according to any preceding claim, wherein the rolls are mounted in a rigid supporting frame, the frame being supported by a casing for the mill.

7. A roller mill according to Claim 5, wherein the casing is formed from sheet metal.

8. A roller mill, comprising a pair of rolls mounted between a pair of rigid side support members such that the rolling surfaces of the rolls are in close proximity to each other at a nip point, and a cheek plate on each side of the rolls, arranged to prevent lateral movement of the material to be milled beyond the ends of the rolls, each cheek plate being mounted on a mounting member which can be caused to flex towards and away from the rolls by means of an adjustment member bearing against the cheek plate or said mounting member, the adjustment member being displaceably mounted in the side support member.

9. A roller mill according to Claim 8, wherein each adjustment member is a screw mounted in a threaded hole in one of the side support members.

10. A roller mill according to Claim 8 or 9, wherein the mounting member is a body panel forming a part of the body of the mill.