GB2025260A

GB2025260A - Roll for Sugar Cane Mills

Info

Publication number: GB2025260A
Application number: GB7924713A
Authority: GB
Original assignee: Maschinenfabrik Buckau R Wolf AG
Current assignee: BWS Technologie GmbH
Priority date: 1978-07-15
Filing date: 1979-07-16
Publication date: 1980-01-23
Also published as: DE2831214A1; GB2025260B; NL7905063A; IN151722B; DE2831214C2; FR2434202B1; FR2434202A1

Abstract

Roll for a sugar cane mill having wear-resistant rings (8-11) ring 11 not being shown for mounting on a steel tubular roll member (2) of the roll, each ring consisting of corrosion resistant material and being coated on its surfaces, that are intended to face the material to be worked, with a granular material showing high resistance to wear, this coating being provided at the time of manufacture so as to lengthen the available period of use of the ring. <IMAGE>

Description

SPECIFICATION Roll for Sugar Cane Mills This invention relates to a roll for a sugar cane mill.

In practice, mill rolls, particularly for the extraction of sugar cane, have only been used in a solid constructional form. Depending on the size of the mill, the roll consists of a forged steel core, on the central section of which, after machining, is shrunk a shell of grey cast iron. The grey cast iron shell is provided with a large number of encircling conical grooves with an angle of 500 or more. These grooves serve for the better discharge of the juice and also for increasing the angle of friction between the material being conveyed and the roll (German Patents Nos.

275,486 and 433,967).

Such rolls, even when they are initially provided with a surface turned to be as rough as possible, show after a short time the disadvantage that very quickly they are worn smooth because of the high silicic acid content of the sugar cane and the high pressing pressure, so that the material being worked is then only incompletely drawn into the mill. In order to overcome these disadvantages, it has already been proposed long ago to provide the roll with wear-resistant rings (German Patent No.

251,791). Rolls of this type could not be used in pactice, however, because the rings did not provide useful operating times longer than those of the hitherto usual heavy or solid rolls, because even after being in operation for a short time, the surfaces of the rings were also worn down until smooth and had to be very often replaced under difficult conditions. Because the surfaces of the rolls were worn down until smooth, the sugar cane to be extracted was no longer uniformly gripped by the rolls, so that the extraction output decreased.

According to the present invention, there is provided a wear-resistant ring for mounting on a steel tubular roll member of a roll for a sugar cane mill, the ring consisting of a corrosion resistant material and being coated on its side, that is to face the material to be worked, with a granular material showing high resistance to wear.

Accordingly, the fundamental idea is to be seen in the fact that the surface of the roll is already to be provided at the time of manufacture with a depth of roughening so as to lengthen the available period of use. The surface roughening can be accurately predetermined by the choice of the granulation which is used for the wearresistant coating, so that also the gripping capacity of the rolls and thus the coefficient of friction can be established in advance and this can be kept constant over a relatively long period of time, and this, in turn, because of improved transport of the sugar cane through the mill installation, means an optimisation of the extraction capacity.

As well as the gripping capacity of the roll surface being maintained for a relatively long time, there is also the advantage that the roll body, consisting simply of structural steel, is inexpensive and only has to take up the forces arising from the operation of the mill. The wearresistant rings only have to serve the purpose of transporting and crushing the sugar cane.

Moreover, they may be made substantially thinner by comparison with the known rings.

An additional advantage is to be seen in the fact that, with the provision of the present rings, the rolls are very much lighter than the prior heavy roll construction and, as a result, the dispatch of a completely assembled mill becomes possible. Consequently, expense for assembly can also be saved. The operational procedure may additionally be simplified by each wear-resistant ring consisting of two or more segments, which are fixed relatively to one another by means of noses or projections engaging in the roll body and being held with rings on the latter. With this constructional form, any damaged wear-resistant rings can be replaced without dismantling the roll.

For a better understanding of the invention and to show how the same may be carried into effect, reference will now be made, by way of example, to the accompanying drawings in which: Figure 1 is a diagrammatic elevation of a complete roll for a sugar cane mill, Figure 2 is a partial section through the roll, Figure 3 is a section on the line A-B of Figure 2, Figure 4 shows another form that the wearresistant rings can take, Figure 5 is a section on the line C-D in Figure 4, and Figure 6 is an enlarged, sectional view of a typicai wear-resistant ring.

Referring to Figures 1 to 3, the roll 1 consists of a tubular roll body 2, on each end of which is arranged a journal 3,4. A driving journal 5 is arranged on the journal 4. The journals 3 and 4 and also the driving journal 5 may be tubular, and the journal 5 may have a solid square end 5a.

The ends of the roll body 2 carry respective discs 6,7, these discs being connected by means of screw bolts 24 to the roll body 2. With a sugar cane mill having several rolls, a top roll may comprise projecting end discs 6 and 7, just as shown in the example, and a bottom roll may comprise flush discs 6 and 7. After one of the two end discs is fixed, four wear-resistant rings 8 to 11 are for example, as represented in the example, separately pushed onto the roll body 2 and are respectively connected by means of clamping elements to the body 2 so that they can be released.

One concievable and simple fixing means is the tongue and groove connection, the tongue and the groove being respectively fixed half on one or other wear-resistant ring. In Figures 2 and 3, clamping means 18 are shown, consisting in each case of two triangular rings 19 and 20, into which are introduced trapezoidal rings 21 and 22, a rearward one of which (22) being provided with a threaded bore and the forward ring (21) with a through bore. By means of a threaded screw bolt 23, the two rings 19 and 20 are forced against the roll body 2 and the corresponding wearresistant ring 8, 9,10 or 11. In this way, the rings 8 to 11 are locked in relation to the roll body 2.

When the last wear-resistant ring has been tightened and fixed by means of the clamping means 18, the second end disc is fixed.

A ring packing 14 is provided between the internal diameter of each and disc 6 and 7 and the respective journals 3,4. Another ring packing 1 5 is provided on the internal surface of each disc, between the latter and end face of the adjoining wear-resistant ring. Packing rings 1 6, 1 7 are likeways provided between the end faces of the separate wear-resistant rings. These packings ensure that the acid sugar juice does not reach the roll body 2, consisting of a simple structural steel and does not cause premature corrosion of the body.

The wear-resistant rings 8 to 11 consist of a corrosion resistant material such as a stainless steel, for example, a chrome-nickel steel, and are thus resistant to attack by acid sugar juices. So that there is a sufficient coefficient of friction between the sugar cane to be crushed and the surface of the roll, the wear-resistant rings are initially provided with encircling, trapezoidalsection grooves 25, of which the angle of opening is between 1=48 and cr2=30 (Figure 6). The opening angle is advantageously 400.

Furthermore, the surface of each of the rings 8 to 11 is coated, particularly on its side facing the material to be worked, with a granular material 12 showing high resistance to wear. The internal surfaces of the end discs 6 and 7 are coated with the same material 13 with high wear resistance.

Such material (12, 13) can be provided by industrial diamonds or a mixture of about 87% tungsten carbide and about 13% cobalt for the wear-resistant coating; the thickness of such material can be 0.05 to 1.0 millimeters, with a possible roughness depth of 20-200,u.

The industrial diamonds can be applied with a suitable binder or galvanically, for example, in a nickel bath with nickel sulphate or the like. Such a wear-resistant layer is to be applied in a manner known per se and with simplest possible means to the wear-resistant rings. Any other material with high resistance to wear can also be considered for forming a wear-resistant coating.

As shown in Figure 6, juice-discharge channels 26 are arranged at the base of each second or third groove 25. Since the sugar cane to be crushed does not pass into these channels 26 and is therefore also unable to cause any wear therein, it is possible in the channels 26 to dispense with any coating with a material showing high resistance, so that the material 1 2 only coats the surfaces of the grooves 25 themselves. In addition to the juice-discharge channels 26, the surfaces of the wear-resistant rings 8 to 11 are also provided with transversely-extending juice channels 27.

Figures 4 and 5 show another constructional example. In this case, the wear-resistant rings 8 to 11 consist of multi-part segments. Thus, in this example, the ring 8' is segmented so that it consists of three separate elements 8a, 8b and 8c. Each element is provided with a projection 28a, 28b or 28c projecting into recesses in the roll body 2. By means of a clamping ring 29, the segments 8a to 8c are locked on the roll body 2.

The clamping ring 29 is formed as a packing ring, so as thereby to prevent any acidic sugar juice reaching the roll body 2. In addition, a fixing ring 30 is provided between each of the adjacent rings 8' and 9', the ring 30 also being constructed as a packaging or sealing ring. The construction of this roll in other respects is the same as that previously described.

It is also conceivable that the roll body 2 may be of stainless steel and that the juice discharge channels 26 may be lead into the interior of the roll body 2. The extracted sugar juice can be discharged through a sump drainage device, which is guided through hollow shafts. It is also conceivable to provide an end opening with a juice-collecting device arranged there-beneath.

With such a development of the roll, the remainder of the roll construction, as described above, would not be modified.

Claims

1. A wear-resistant ring for mounting on a steel tubular roll member of a roll for a sugar cane mill, the ring consisting of a corrosion resistant material and being coated on its side, that is to face the material to be worked, with a granular material showing high resistance to wear.

2. A ring as claimed in claim 1, wherein the granular material coating has a thickness of from 0.05 to 1.0 millimetres.

3. A ring as claimed in claim 1 or 2, wherein the roughness depth of said granular material coating is between 20-200 y.

4. A ring as claimed in claim 1,2 or 3, wherein said granular material coating consists of industrial diamonds, which are applied with a suitable binder to the ring.

5. A ring as claimed in claim 1, 2 or 3, wherein said granular material coating consists of a mixture of about 87% tungsten carbide and about 13% cobalt.

6. A ring as claimed in any one of the preceding claims and comprising two or more segments which are fixable in relation to one another by projections which can engage with the steel tubular roll member.

7. A ring as claimed in claim 6, when mounted on a said steel tubular roll member, there being a clamping ring serving to hold the segments in place on said roll member.

8. A ring as claimed in any one of claims 1 to 5 and further comprising clamping means in the form of wedge members which serve to tighten the ring on a said steel tubular roll member.

9. A ring as claimed in any one of the preceding claims and comprising trapezoidal section grooves on its working surface, of which grooves each second or third groove comprises a juice-discharge channel in its base, said granular material being provided on the surfaces of said grooves.

10. A ring as claimed in claim 9, wherein the angle of opening of each groove is between 300 and 48 .

11. A ring as claimed in any one of the preceding claims, wherein said corrosion resistant material is stainless steel.

12. A wear-resistant ring for mounting on a steel tubular roll member of a roll for a sugar cane mill, substantially as hereinbefore described with reference to Figures 1, 2, 3 and 6 or Figures 1,4, 5 and 6 of the accompanying drawings.

13. A roll for a sugar cane mill, the roll comprising a plurality of wear-resistant rings each as claimed in any one of the preceding claims, the rings being mounted axially on a said roll member, there being sealing means between the rings and said roll member to prevent sugar juice from reaching said roll member.

14. A roll as claimed in claim 13, wherein the axially outermost rings are provided on their outermost sides with end flanges.

1 5. A roll as claimed in claim 14, wherein said end flanges are each comprised by a disc mounted on the adjoining ring.

16. A roll as claimed in claim 14 or 15, wherein said flanges are coated, on their surfaces that are intended to face the material to be worked, with said granular material.

17. A roll for a sugar cane mill with wearresistant rings each as claimed in any one of claims 1 to 12, substantially as hereinbefore described with reference to Figures 1, 2, 3 and 6 or Figures 1, 4, 5 and 6 of the accompanying drawings.