Rotary mill particularly for the ceramics sector

Abstract

 In a mill comprising a cylindrical drum (6) of horizontal axis provided with two end ports (8) for loading and discharge respectively, and mounted on intermediate support members in such a manner as to be able to rotate about itself under the control of a drive system, said support members consist of two opposing pairs of idle contact rollers (4) of hard material having their axes parallel to the drum axis, said drive system consisting of a belt transmission (9).

Description

[0001] This invention relates to a continuous mill of horizontal drum type, a typical but non-exclusive use of which is in the ceramics sector for crushing material used in tile manufacture.

[0002] For such processes mills are known comprising a large cylindrical drum of horizontal axis which is rotated about itself and comprises two opposing coaxial ports for loading the material to be crushed and for discharging the crushed material respectively.

[0003] A problem connected with such mills, and for which an adequate solution has not been found, is to provide a support system able to adequately withstand the weight of said large drum and the material contained in it.

[0004] In a first known solution, said support is provided by two projecting hollow cylindrical hubs coaxially positioned on the front and rear ends of the drum, and through which the material entering and leaving passes respectively.

[0005] With these hubs there are associated respective relatively large-dimensioned bearings housed in suitable supports.

[0006] The aforedescribed known system has proved unsatisfactory for the following reasons:

• firstly for the fact that such bearings and their supports are excessively costly, because by virtue of their dimensions they represent non-standard components,
• and secondly because such hubs offer only a relatively low capacity, inadequate for the processes and high productivity which characterise current ceramics production.

[0007] At this point the most logical thing to do would seem to be to increase the internal diameter of said hollow hubs as much as possible, obviously while still achieving the necessary strength, but this would require the use of still larger bearings, of incompatible cost.

[0008] In another known solution, the drum is supported by two opposing pairs of contact rollers with axes parallel to each other and to the drum axis, they being coated with rubber or another elastomer of good friction coefficient, and are driven to rotate the drum.

[0009] This other solution has the drawback that the contact regions between the motorized drive rollers and the drum are relatively small in area, with the result that the rubber layer which coats the support and drive rollers undergoes considerable compression, so limiting its life.

[0010] The mill has therefore to be halted fairly frequently to replace the rollers, with consequent renovation costs and loss of production.

[0011] The main object of this invention is to obviate the aforesaid within the context of a simple and rational construction.

[0012] Said object is attained according to the invention by a mill having the characteristics defined in the claims.

[0013] Specifically, the drum of horizontal axis is positioned on two opposing pairs of idle contact rollers of hard material having their axes parallel to the drum axis, the drum being rotated by at least one belt transmission.

[0014] The aforedescribed solution attains all the objects of the invention in that all the initially stated problems connected with perforated hubs and motorized rollers are eliminated.

[0015] Said idle rollers are preferably constructed of steel, and more preferably of surface-treated or special steel, with these there corresponding respective metal rolling tracks on the drum.

[0016] In addition, according to the invention said belt transmission preferably comprises two separate drive units, each of which comprises a plurality of V-belts.

[0017] Advantageously said drive units are associated with respective drum parts outside the central drum portion lying between said pairs of idle steel rollers.

[0018] The advantage deriving from said arrangement is that the tension of the belts of said units provides a bending moment which balances most of the bending moment due to the weight of said central drum portion, with consequent excellent bearing of said idle rollers against the respective rolling tracks.

[0019] Suitable means are also provided for adjusting the belt tension.

[0020] For a better understanding of the characteristics and constructional merits of the invention, reference is made hereinafter to the figures of the accompanying drawings, on which:

[0021] Figure 1 is an external side elevation of the invention; and Figure 2 is a view to an enlarged scale in the direction II of Figure 1.

[0022] Said figures, and in particular Figure 1, show two robust shoulders 1 extending upwards from the floor 2 and upperly provided with a structure 10 comprising two opposing pairs of coaxial supports 3.

[0023] In each pair of coaxial supports 3 there is rotatably mounted a steel roller 4 against which there rests a respective metal annular rolling track 5 associated with the horizontal drum 6 of the continuous mill 7.

[0024] Said rollers 4 and said tracks 5 are either surface-treated or constructed of special steel.

[0025] The two tracks 5 are spaced from the end transverse walls of the drum by the same distance, said walls each comprising a central aperture 8 (of which only one is visible in Figure 2).

[0026] In each part of the drum 6 situated external to said tracks 5 there is provided a series of identical equidistant circumferential grooves 9 of V cross-section, with which a corresponding number of V-belts 11 engage and pass about an underlying grooved horizontal drive roller 12.

[0027] The drive roller 12 is driven by a geared motor unit 13 with incorporated step-down gear, said drive roller 12 and unit 13 being positioned on a flat frame 14 hinged at 15 to a support base 16.

[0028] Finally, between said base 16 and said frame there are interposed two screws 17 for adjusting the tension of the belts 11.

[0029] The merits and advantages of the invention are apparent from the aforegoing and from an examination of the accompanying figures.

Claims

1. A mill, comprising a cylindrical drum (6) of horizontal axis provided with two end ports (8) for loading and discharge respectively, and mounted on intermediate support members in such a manner as to be able to rotate about itself under the control of a drive system, characterised in that said support members consist of two opposing pairs of idle contact rollers (4) of hard material having their axes parallel to the drum axis, said drive system consisting of a belt transmission (9).

2. A mill as claimed in claim 1, characterised in that said idle rollers are constructed of metal, such as special steel, with said rollers there corresponding respective annular metal rolling tracks on the drum.

3. A mill as claimed in claim 1, characterised in that said belt transmission comprises two separate drive units, each comprising a series of equidistant V-belts passing endlessly about a grooved band associated with the drum and a motorized grooved roller (12).

4. A mill as claimed in claim 3, characterised in that said two drive units are situated external to said opposing pairs of idle rollers.

5. A mill as claimed in claim 3, characterised by comprising adjustment means (17) for selecting the tension of the belts of said drive units.

6. A mill as claimed in claim 5, characterised in that said adjustment means (17) comprise, carrying the drive means, a flat frame (14) hinged at one end and engaged at its other end with a tensioning screw (17).

Drawing