US3680799A

US3680799A - Linings for rotary mills

Info

Publication number: US3680799A
Application number: US75125A
Authority: US
Inventors: Stig Lennart Hallerback
Original assignee: Trelleborgs Gummifabriks AB
Current assignee: Trelleborgs Gummifabriks AB
Priority date: 1969-09-25
Filing date: 1970-09-24
Publication date: 1972-08-01
Anticipated expiration: 1989-08-01
Also published as: SE335665B; CA923866A

Abstract

A lining for rotary mills comprising lifting and lining elements renewable by rotation and of a star-shaped cross section having substantially uniform points. The elements of the lining may have inner cooling passages constituted by tubes. The tubes may serve as rotational axes and supporting elements for the elements of the lining.

Description

nited States Patent Hallerback Aug. 1, 1972 [54] LININGS FOR ROTARY MILLS [56] References Cited [72] Inventor: gtigdbennart Hallerback, Lunda, UNITED STATES PATENTS we en 1,470,597 10/1923 Denny etal ..241/183 X [731 Asslgnee- 53%? u g g g' 2,887,276 5/1959 Minarik ..24l/67 e we 2,909,335 10/1959 Janelid ..241/183 [22] Filed: Sept. 24, 1970 3,194,506 7/1965 Bourne et al ..241/ 182 X 21 A l.N 75125 1 pp 0 Primary Examiner-Robert L. Spruill Attorney-Beveridge & De Grandi [30] Foreign Application Priority Data Sept. 25, 1969 Sweden ..l3162/69 ABSTRACT A lining for rotary millscomprising lifting and lining "241/ 51/ elements renewable by rotation and of a star-shaped [58] Field 182 cross section having substantially uniform points. The

elements of the lining may have inner cooling passages constituted by tubes. The tubes may serve as rotational axes and supporting elements for the elements I of the lining.

18 Claims, 7 Drawing Figures PATENTEUAUI; 1 4912 sum 1 or 4 7 4 (Emmer- H/uzm sic/e PATENTEDAUG 1 I972 saw u. nr 4 FIGS LININGS FOR ROTARY MILLS When rotary mills are used for grinding of mostly highly abrading material the inner circumferential surface and side walls of the rotary mill barrel will be subjected to substantial wear. This wear unfavorably affects the operating economy of the mill since the efficiency of the mill is greatly reduced when the lifter or driver system of the sheet metal barrel becomes worn. This occasionslong break-downs and disturbances as well as expensiverepairs. To improve the operating economy of the mill itis lined with some wear-resistant material, such as rubber. The difficulties which, however, arise with a conventional lining in the mills first of all is a non-uniform wear of the lining elements and secondly the difficulty of keeping the temperatures at such a low level that the lining elements will not suffer from overheating. This is particularly troublesome in grinding dry materials. r

One object of this invention is to provide a lining for mills, in which worn-out elements can be rapidly exchanged by extremely simple measures. Another object of this invention is to provide an efficient cooling system for the lining elements.

The above objects are realized by the present invention which provides a lining for a rotary mill barrel comprising lining elements made from a wear resistant material and mounted soas to protect the inner side of themill barrel, lifter and driver'elements made from a wear resistant material and constituting some of said lining elements, said lifter and driver elements projecting from the remaining elements, wearing portions on said lifter and driver elements, said lifter and driver elements having a substantially star-shaped cross section the points of which constitute said wearing portions, mounting means for said lifter and driver elements permitting renewal of the wearing portion of said lifter and driver elements by simple rotation of said elements.

According to the invention, the lifter and driver elements are formed substantially according to two dif ferent types, one type serving primarily as a protection for the sheet metal mantle of the mill while'the other type, apart from its mantle protective function, also serves as a driver and lifter for the charge of the mill, and at least one of the elements of the lining is formed with a star-shaped cross. section having substantially uniform points, and said lining element which preferably is a driver and lifter element is so adjustable by rotation that only one of the projecting points of the star-shaped section is subjected to wear, whereby the wearing portion of the star-shaped lining section element is easily renewable by simple rotation of the respective element.

Further objects of the invention and the features of and the advantages gained by the invention will become apparent from the following description, in which reference is made to the accompanying drawings in which:

FIG. '1 is a perspective view and cross section of a ball mill;

FIGS. 2-6 are sections of alternately formed mantle segments for said mill;

FIG. 7 is a perspective view illustrating various possibilities of arranging cooling systems in the mill.

FIG. 1 shows a mill consisting of a cylindrical mantle 1 with end walls 2 and 3, respectively. The material 4 to be crushed or ground is supplied to the mill through a connecting socket or inlet 5 and is carried away from the mill through a discharge socket or outlet 6. The cylindrical mantle surface 1 of the mill in the outermost layer thereof consists of a supporting steel structure 8. To protect the outer steel mantle from wear the latter is coated internally with two different types of lining panels 9, 10 made from some type of wear resistant material, such as rubber. One type of lining panels or elements 9 has the main purpose of protecting the steel structure while the other type of lining elements 10, apart from their protective function also constitutes drivers and lifters for the material to be ground or crushed. When the mill is in operation there always arises a higher wear of said lifter elements 10, whereby the efficiency and performance of the mill are reduced. For this reason, the'lifter element 10 according to this invention has been given a star-shaped cross section, in the present instance with three points, so that it is possible to introduce a new lifter into the mill proper by rotating the element through one division. In that way,

the driver or lifter elements can be utilized three times before they are so worn out that they have to be dispensed with. FIGS. 2-6 show more in detail how the lining elements proper may be arranged.

In FIG. 1, the. lifter element 10 has been formed with a central hole or tube 11 which is fixedly or movably centered in bothend walls 2 and 3. Liquid coolant or cooling air can be supplied through the tubes, whereby the operatingv temperature of the wearing elements is considerably lowered, which makes for an appreciably increased life of said elements. If desired, the wearing elements 9 also can be provided with cooling passages according to the above system, see in FIG. 3. The lowered temperature and the improved degree of exploiting the lining elements gives the mill in total a very good operating economy.

FIG. 2 shows a cross section through part of the outer barrel of the mill. The lifter elements 12 are in the form of regular stars havingv three

points

13, 14 and 15. The lifter element 12 will become accessible when the door 16 of the outer sheet metal mantle l is opened. If at an inspection of the driving and lifting portion 13 of the lifter element the said portion shows a wear such as that marked by the dotted line 17 the driving and lifting effect of the element 12 is so low that the driving and lifting portion must be exchanged. To do this, the element is withdrawn, rotated through counterclockwise and then reintroduced into the gap between the two wearing elements 9, the function of the lifter element being again as good as if an entirely new unit had been inserted. After the rotation of the lifter element the door 16 is replaced, spring elements 18 keeping the lifter element 12 in correct position. At the center of the lifter element 12 there is provided a longitudinal passage or a longitudinal tube 19 through which a liquid coolant or cooling air is supplied. The lining elements 9 between the lifter elements 12 are made in the form of panels in FIG. 2 and have an embedded fastening metal sheet 20 which can be secured by bolts in a known manner against the barrel 1. The lining elements 9 'must be made so thick in their wear resistant portion that their life on the whole corresponds to the time it takes to wear down all three drivers and

lifters

13, 14 and 15 of the element 12.

FIG. 3 mainly shows the same type of lining element as FIG. 2, with the difference, however, that the lining elements 9 have two longitudinal tubes 21 which are connected to the end walls of the mill on the same principle as the tube for the rotatable lifter elements 12. By this arrangement the entire lining of the mill can be given a much lower operating temperature than what is the case in conventional mill linings.

FIG. 4 shows a special combination of rotatable driver and lifter elements 12 and lining elements 9. The driving and lifting portion 13 of the elements 12 in this embodiment to a certain extent constitute part of the lining element 9 since the latter has been designed with an inclined supporting portion 14 which braces the rear side of the driving and lifting portion 13. As a result, the driving and lifting portion 13 will have a greater stability andsupporting ability. Should it prove at an inspection that the wear of the driving and lifting portion 13 is so large as illustrated by way of example by the dotted line 22 the lifter element is rotated whereby a practically new lining is obtained. By building a mill lining in this way use can be made of a very good rubber quality for the heavily stressed and worn lifter elements, whereas the intermediary lining elements 9 may be made in a cheaper and economically more advantageous quality.

As will appear from FIG. self-setting or self-adjusting mantle elements 23 can be mounted between the lifter elements 12. These self-setting or self-adjusting elements in their upper parts have a longitudinal tube 24, about which the element 23 is movable. This arrangement may be of advantage in the total mounting of the lining elements and provides simple and efficient cooling properties on the same principle as for the rotatable lifter element.

Like the earlier FIGS., FIG. 6 shows a number of lifter elements 12. Provided between these lifter elements are similar rotatable mantle elements 25 which can thus also be renewed three times according to the degree of wear.

FIG. 7 very diagrammatically shows how the cooling systems through the lining elements can be caused to function. At 26 there is shown quite simply how the central tubes or holes freely open on the outer side 27 of the mill end wall. At the rotation of the mill in the direction of the arrow air under pressure or cooling water 28 may be injected when the tube mouths go past a fixed nozzle 29. A type of self-circulation for water may be arranged, for example as shown at 30 with a number of inlet nozzles directed in opposition to the direction of rotation of the barrel. If said inlet nozzles are extended as shown at 31 they will be able to collect so much water when passing a water reservoir 32 that a suitable speed of the flow of cooling water may be obtained through the central tubes. Considerably more developed cooling arrangements may certainly be provided, but the systems shown and described are merely meant to aim at indicating the basic principle of the cooling function.

What I claim and desire to secure by Letters Patent 1. A lining for a rotary mill barrel comprising lining elements made from a wear resistant material and mounted so as to protect the inner side of the mill barrel, lifter and driver elements made from a wear resistant material and constituting some of said lining elements, said lifter and driver elements projecting from the remaining lining elements, wearing portions on said lifter and driver elements, said lifter and driver elements having a substantially star-shaped cross section the points of which constitute said wearing portions, mounting means for said lifter and driver elements permitting renewal of the wearing portion of said lifter and driver elements by simple rotation of said elements.

2. A lining as claimed in claim 1 wherein at least the star-shaped rotatable lining elements have a central through tube which may be used for cooling the elements.

3. A lining as claimed in claim 2 wherein the central tube is mounted in the end walls of the rotary mill barrel in such a way that the rotatable star-shaped lining element can perform a radial movement.

4. A lining as claimed in claim 1 wherein the rotatable lining elements are accessible from outside the periphery of the mill barrel by suitably arranged door elements.

5. A lining as claimed in claim 1 wherein the rotatable lining elements are resiliently clamped from the outside towards the center of the mill barrel so that large tolerances may be taken up at the contact with the remaining lining elements.

6. A lining as claimed in claim 1 wherein both the star-shaped lining elements constituting rotary drivers or lifters as well as mantle lining elements which are arranged between the star-shaped lining elements are provided with longitudinal central tube systems for cooling the lining material.

7. A lining as claimed in claim 6 wherein the mantle elements arranged between the star-shaped lining elements are rotatably mounted about a through tube passing longitudinally of said mantle elements and serving as a cooling tube for the lining material.

8. A lining as claimed in claim 6 wherein said mantle elements like said lifter elements, are formed with a star-shaped cross section and are adjustable by rotation into different working positions.

9. A lining as claimed in claim 2 wherein said central tubes are arranged to receive coolant, through injection nozzles located at the end wall portions of the mill barrel and directed towards said portions.

10. A lining as claimed in claim 9, wherein tubular nozzles provided in the end walls are so formed for the cooling operation that the rotational speed of the mill results in a circulation effect in the tube system of the lining elements.

11. A lining as claimed in claim 9 wherein tube connections for cooling at the mill end walls are extended peripherally in such a way as to be able to take up on their rotation a suitable amount of liquid coolant to cool the tube system extending through the lining elements.

12. A lining as claimed in claim 7 wherein said through tubes are mounted in the end walls of the rotary mill barrel so that the rotatable lining elements can perform a radial movement.

13. A lining as claimed in claim 7 wherein the rotatable mantle lining elements are accessible from outside the periphery of the mill barrel by suitably arranged door elements.

14. A lining for a rotary mill barrel comprising lining elements made from a wear resistant material and mounted so as to protect the inner side of the mill barrel, lifter and driver elements made from a wear resistant material and constituting some of said lining elements, said lifter and driver elements projecting from the remaining lining elements, wearing portions on said lifter and driver elements, some of said lifter and driver elements having a substantially star-shaped cross section the points of which constitute said wearing portions, mounting means for said some of said lifter and driver elements permitting renewal of the wearing portion of said some of said lifter and driver elements by simple rotation of said elements.

15. A lining as claimed in claim 14 wherein some

Claims

1. A lining for a rotary mill barrel comprising lining elements made from a wear resistant material and mounted so as to protect the inner side of the mill barrel, lifter and driver elements made from a wear resistant material and constituting some of said lining elements, said lifter and driver elements projecting from the remaining lining elements, wearing portions on said lifter and driver elements, said lifter and driver elements having a substantially star-shaped cross section the points of which constitute said wearing portions, mounting means for said lifter and driver elements permitting renewal of the wearing portion of said lifter and driver elements by simple rotation of said elements.

15. A lining as claimed in claim 14 wherein some remaining elements are also rotary elements of star-shaped configuration.

16. A lining as claimed in claim 14 wherein at least said star-shaped rotatable lining elements have a central through tube which may be used for cooling the elements.

17. A lining as claimed in claim 15 wherein said star-shaped remaining elements have a central through tube which may be used for cooling the elements.

18. A lining as claimed in claim 16 wherein said rotatable lining elements are accessible from outside the periphery of the mill barrel by suitably arranged door elements.