WO1993013857A1

WO1993013857A1 - Roller mill for cereals

Info

Publication number: WO1993013857A1
Application number: PCT/EP1993/000010
Authority: WO
Inventors: Francesco Piacentini
Original assignee: Golfetto SpA
Current assignee: Golfetto SpA
Priority date: 1992-01-20
Filing date: 1993-01-07
Publication date: 1993-07-22
Anticipated expiration: 1994-07-20
Also published as: IT1260810B; ITVE920005A0; ITVE920005A1; AU3348093A

Abstract

A roller mill for cereals with a structure comprising a pair of shoulders (4), to which supports (18) are applied for at least one pair of grinding rollers (12, 14) extending parallel to each other from one shoulder to the other and provided with journals (10) passing through said shoulders (4) via substantially horizontal slots (8), characterized in that both the supports (18) for the two rollers (12, 14) are pivoted to the machine shoulders (4) below the grinding axis, are connected to each other above said axis when in their operating state, and are formed in at least two separable parts (18, 20) to enable them, after being separated, to be completely turned down about the axis on which they are pivoted to the shoulders for the purpose of roller replacement, and to enable the roller journals (10) to be rolled along the lower edge of said slots (8) for transferring said rollers to the outside of the roller mill.

Description

ROLLER MILL FOR CEREALS

This invention relates to a roller mill for cereals.

Roller mills for cereals are known, comprising one or, more frequently, two pairs of counter-rotating grinding rollers, one of which is fixed relative to the machine shoulders and the other of which can be moved relative to the fixed roller and is provided with mechanical members for adjusting the parallelism between it and the fixed roller and for controlling its approach to and withdrawal from this latter. As the speed of rotation of the fixed roller is generally greater than that of the movable roller, the fixed roller wears more rapidly and has to be replaced more frequently. To facilitate this more frequent replacement it is preferable for the fixed roller to be positioned on the outside and the movable roller on the inside.

Both the fixed roller and the movable roller are gnerally provided with bearings supported by supports mounted on the machine shoulders. The supports for the fixed roller are fixed to the machine shoulders, whereas the supports for the movable rollers are pivoted on pins which are eccentrically pivoted to said shoulders.

To replace each roller the relative supports have to be released from the machine load-bearing structure, after which the roller has to be lifted by special equipment, generally of suspended type and more or less matching the outline shape of the machine.

An object of the invention is to replace the grinding rollers in a considerably more simple, comfortable and rapid manner.

A further object of the invention is to effect this replacement without the need to use special equipment, but simply by using a truck slidable along the floor of the grinding hall.

These and further objects which will result from the following description are achieved according to the invention through a roller mill for cereals as claimed in claim l..

A preferred embodiment of the present invention is described in greater detail hereinafter with reference to the accompanying drawings, in which:

Figure 1 is a schematic side view of a roller mill according to the invention of symmetrical type with the right half in operation and the left half undergoing grinding roller replacement;

Figure 2 is a detailed side view to an enlarged scale showing the supports for the grinding rollers and their adjustment linkage; and Figure 3 is a front view thereof of Figure 2.

As can be seen from the figures, the roller mill according to the invention is shown in its symmetrical form with two pairs of grinding rollers and comprises a structure formed from two cast iron shoulders 4 joined together by two front walls 6, plus an upper internal structure 2. Each shoulder 4 forms with the structure 2 a horizontal slot 8, open towards the front edge of the shoulder, for passage of the journals 10 of the .two grinding rollers 12 and 14 of each pair.

In proximity to the shoulders 4 the two journals of each roller 12, 14 are supported by bearings 16 housed in corresponding open supports 18 closed by front covers 20..

Each front cover 20 is fixed to the relative support 18 by screws 22, and each support 18 is pivoted lowerly to the relative shoulder 4 on a pin 24, 24' projecting outwards therefrom, and is also provided with an upper appendix 26 through which a tie rod 28 passes to connect the supports 18 for the two rollers 12, 14 together when in the operating state.

For this purpose the tie rod 28, which is fixed at its centre to the fixed structure of the roller mill, has its two threaded ends engaged by nuts 30, 30', of which the first 30 is directly in contact with the support 18 for the fixed roller 12, whereas the second 30' adheres to a series of cup springs 32 interposed between it and the appendix 26 of the support 18 for the movable roller 14. The system connecting together the supports for the two roller 12 and 14 also comprises conventional swinging and centering members, which are not described as they are of known type.

On the pin 24 by which each support 18 for ^'the fixed roller is pivoted to the corresponding shoulder 4 there is pivoted the end of a fork lever 36, which is pivoted at its centre to a pin 38 fixed to the shoulder 4 and is pivoted at its other end to a pneumatic cylinder 40.

The rod 42 of the piston housed in the cylinder 40 is pivoted to the end of a further lever 44 fixed to the pin 24' which is eccentrically connected to the corresponding shoulder 4. To the lever 44 there is pivoted a bush 46, to which threaded rod 48 is axially fixed but is free to rotate within said bush 46. The threaded rod 48 is engaged in the bush 34 and is provided at its outer end with an operating handwheel 50.

The operation of the machine according to the invention is as follows: under normal operating conditions the two grinding rollers 12 and 14 are arranged parallel to each other at the required distance apart for the specific grinding to be undertaken, and are maintained elastically in that position by the opposing effect of the cup springs 32 and other springs 52 interposed between the rollers.

If a foreign body falls between the rollers during grindign, this overcomes the elastic reaction of the cup springs 23 and causes the roller 14 to momentarily withdraw from the roller 12 to prevent them suffering damage. The approach and withdrawal of the movable roller 14 to and from the fixed roller 12 are achieved by the pneumatic cylinders 40, which are fed with compressed air to cause their rod 42, via the lever 44, to rotate the pin 24' which, being eccentric, causes the support 18 for the mobable roller 14 to move so that the corresponding end of this latter approaches or withdraws from the end of the fixed roller 12.

Parallelism between the two rollers is adjusted by the handwheels 50. On rotating each handwheel the corresponding threaded rod 48 rotates with the result that the bush 34 moves along it. This movement causes the fork lever 36 to rotate about the pin 38, hence displacing the cylinder 40, resulting in rotation of the lever 44 and rotation of the eccentric pin 46. For obvious linkage reasons, the axis of rotation of the bush 46 about the lever 44 must coincide with the axis of rotation of the support 18 about the pin 24'.

To remove the rollers 12 and 14 the two nuts 30 are unscrewed from the two supports 18 for the fixed roller 12 so that these are no longer retained by the tie rods 28 and can rotate, bu virtue of the fact that the position of the axis of rotation is vertically external to the axis of rotation of the relative supports 18, in the direction of withdrawal from the movable roller 14 until its journals 10 rest on the lower edge of the slot 8. At this point, after unscrewing the screws 22 the front covers 20 of the relative supports 18 for the fixed roller are removed and the handwheels 50 are completely removed, to enable the rotation of the supports to continue until they disappear below the lower edge of the slot 8 (see the left side of Figure 1) .

Analogous operations are performed for the movable roller 14, with the only difference that in this case the nut 30' is unscrewed.

Having released the two rollers 12, 14 from their supports the roller can be rolled via their journals along the lower edge of the slots 8, until they reach a truck (not shown) which in the meantime has been positioned in front of the roller mill in prolongation of the lower edge of the slots.

The rollers 12 and 14 can hence be removed from . the grinding hall without requiring any lifting equipment.

From the aforegoing it is apparent that the roller mill according to the invention is particularly advantageous, in that it enables the grinding rollers to be replaced in a very simple and rapid .manner, which inter alia does not require any special equipment for lifting the rollers.

In addition, because of the fact that the grinding rollers are supported on the pins 24 and 24' onto which the forces arising from the grinding are discharged, and that the same pins 24 and 24' plus pins 38 support all the linkages involved in the approach and withdrawal of the grinding rollers and their adjustment, it has been possible to concentrate the forces and vibration due to grinding on only a small region of the shoulders 4. The use of suitably dimensioned cast iron in this region is to be considered advantageous as it ensures very stable operation of the roller mill.

Claims

C L A I M S

1. A roller mill for cereals with a structure comprising a pair of shoulders (4) , to which supports (18) are applied for at least one pair of grinding rollers (12,14) extending parallel to each other from one shoulder to the other and provided with journals (10) passing through said shoulders

(4) via substantially horizontal slots (8) , characterised in that both the supports (18) for the two rollers (12,14) are pivoted to the machine.shoulders (4) below the grinding axis, are connected to each other above said axis when in their operating state, and are formed in at least two separable parts (18,20) to enable them, after being separated, to be completely turned down about the axis on which they are pivoted to the shoulders for the purpose of roller replacement, and to enable the roller journals (10) to be rolled along the lower edge of said slots (8) for transferring said rollers to the outside of the roller mill.

2. A roller mill as claimed in claim 1, characterised in that the supports (18) for the two grinding rollers (12,14) are supported by pins (24,24') rigid witht the shoulders (4) and having the line joining their axes lower than the line joining the axes of said rollers (12,14) when in the operating condition, the vertical through the axis of each roller being external to the axis on which the relative supports (18) are pivoted to the shoulders (4) .

3. A roller mill as claimed in claim 1, characterised in- that each support (18) comprises a C-shaped main body and a front cover (20) removably fixed to said main body, to define therewith a housing for a bearing (16) mounted on the journal (10) of said roller (12,14).

4. A roller mill as claimed in claim 3, characterised in that the C-shaped body of each support is provided lowerly with a connection appendix pivoted on the corresponding pin (24,24'), and upperly with a further appendix (26) by which said support (18) is maintained connected, when in operation, to the like support for the other roller of the same pair.

5. A roller mill as claimed in claim 1, characterised by comprising for each pair of grinding rollers (12,14) a pair of cylinders (40) , each pivoted to the end of a lever (36) which is pivoted centrally to the corresponding shoulder (4) , and each housing a piston, the rod (42) of which is pivoted to a second lever (44) fixed to the eccentric pivot pin (24') for the corresponding support (18) of the movable grinding roller, to said lever (44) there being applied a bush (46) which has its axis coinciding with the axis on which the support (18) is pivoted to the pin (24'), and carries a rod (48) which is axially restrained but free to rotate and comprises a threaded portion engaged in a threaded bush (34) pivoted to the opposite end of the lever (36) to that to which the cylinder (40) is connected.

6. A roller mill as claimed in claim 5, characterised in that a removable adjustment handwheel (30) is applied to the outer end of the rod (48) .

7. A roller mill as claimed in claim 5, characterised in that a pivot pin (38) -for the lever (36) is applied to each shoulder (4) .

8. A roller mill as claimed in claim 7, characterised in that at least that portion of the shoulder (4) to which the pivot pins (24,24') for the supports (18) for the grinding rollers (12,14) and the pivot pin (38) for the lever (36) are applied is constructed of cast iron.

9. A roller mill as claimed in claim 1, characterised by comprising a truck to be placed to the side of the roller mill as a prolongation of the lower edge of the slots (8) , to receive the grinding rollers (12,14) after they have been rolled along said slots.