DE2912636A1 - DOUBLE AND MULTI-ROW BALL RING MILL - Google Patents

Description

DOUBLE AND MULTI-ROW BALL RING MILL

The invention relates to a roller mill with spherical Grinding media such as those used for the fine grinding of coal, rocks and earth.

In such roller mills, the coarse-grained grist between the grinding media, which in general perform a circular movement relative to a grinding table, and the grinding table surface finely ground, with the fine grain and the air-dust mixture being carried out by means of an air stream a classifier, usually housed in the same housing, flows through.

It is known to perform ring mills to meet these requirements so that on a perpendicular stationary gear pin a rotating grinding bowl is placed, also race ring or Called grinding table, in which freely movable grinding balls can describe a circular path and on which an upper pressure ring, which does not rotate, exerts the required grinding pressure. This The thrust bearing principle was known as the "Fuller" and "Peters" mill and represents the stand the technology for this type of construction.

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One of the disadvantages of this basic arrangement is the high axial pressure that is exerted on the perpendicular stationary output journal of the gearbox is exercised, which leads to corresponding axial bearings, which - mostly integrated into the gearbox - make it considerably more expensive.

Furthermore, a design in the manner of a radial ball bearing is described in application P 28 29 679.9, the principal disadvantages of the hitherto customary construction, which is comparable with an axial ball bearing, to a large extent degrades.

As before, however, it can be seen that the grinding capacity limit is relative in the case of the single-row arrangement is low and does not meet the requirements that have since increased.

It becomes this grinding capacity limit per mill due to the large ones resulting from the single-row design Grinding track diameter and grinding ball diameter are drawn, leading to a non-linear increase in dimensions and lead to manufacturing costs.

Two-row mills running on the type of axial ball bearings that already have the The advantage of the elimination of the grinding pressure load on the lower rotating grinding table and In this way, disadvantages identified by the corresponding single-row construction are avoided. These early two-tier mills

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however, had difficulty in transmitting the torque to the central rotating grinding ring and to achieve an advantageous flow of grist through the mill.

The invention is based on the object of improving the two-row and multi-row ball mill by that constraining forces on the grinding elements are avoided, there is no axial load on the drive and a flow of ground material favorable for the grinding and sifting process in one or more stages through the one above the other arranged individual grinding steps takes place.

The object is achieved according to the invention in that the rotating, fixed grinding rings between the individual, stacked, fixed grinding rings by means of a double cardan shaft angularly movably driven middle grinding rings in each case in the manner of an angular contact ball bearing assembled grinding balls are supported and centered on the lower fixed grinding rings.

To reduce the dead weight of the rotating grinding rings and grinding balls in the even distribution of the To compensate for effective grinding pressure, the helix angle of the grinding balls of the lower grinding passage of the of the upper balls are different, with all grinding balls involved in the grinding work having the same diameter exhibit.

In order to feed the grist to the grinding balls and to transport the grist over the effective surfaces of the

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To favor grinding balls and the grinding tracks including the discharge and as large as possible To be able to use the proportion of the grinding ball surface for grinding work are material guide rings, which rest loosely on the grinding balls and rotate with them.

To change the grinding pressure according to the requirements of the grinding and apply it evenly can, are acting between the non-rotating grinding rings, equipped with (gas) springs Working cylinder arranged.

An embodiment of the invention is shown schematically in the drawing and is described below explained in more detail.

The single figure shows a vertical section through a two-row ball ring mill with a two-stage grinding process.

The transmission 1, which is completely free from vertical forces resulting from the grinding pressure, transmits Angularly movable via a double cardan shaft 2, the drive torque is applied to the middle rotating one Grinding ring 3, which is guided over the lower grinding balls 4 on the standing lower grinding ring 5 and is centered. The one applied to the upper non-rotating grinding ring 6 by the working cylinder 7 Grinding pressure is in turn from the upper grinding balls 8

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transferred to the middle grinding ring 3, the rotation of which all balls for rolling circulation brings. In the example shown, the material to be ground is first fed to the upper grinding stage via the feeder 9 fed, the classifier size via the funnels 10, 11 to the apex of the grinding balls flow in. The pre-ground material emerging from the upper grinding passage is, with the inclusion of a Sifter effect through the air nozzle ring 12 partly already blown up into the sifter, partly through the material guide ring 13 to the apex the lower grinding balls. The loose material guide ring 13 is with by friction circulated and its movements prevent the material from clogging Passage between rings 13 and 3.

After the material to be ground has emerged from the lower grinding stage, it falls into the funnel 14, which is attached to the outlet 15 connects. The ground material accumulating in the funnel 14 is removed by shovels 16, which circulate with the cardan shaft protective tube 17, moved to the outlet 15.

The advantages that can be achieved with the invention are a relatively low overall construction cost, because the effective grinding surface of the grinding elements can be accommodated on a small grinding path diameter is, the ball diameter can remain small in relation to the total grinding capacity.

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The grinding pressure distribution can be designed in any way thanks to the angular contact ball bearing arrangement; the balls become safely guided, even in the event of wear and tear, the direction of flow of the grist is generally vertical top down. The transmission, which can be completely relieved of vertical forces, is light and reliable and inexpensive.

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Claims (4)

TWO AND MULTI-ROW BALL RING MILL Patent claims: 1. Roller mill with spherical, guided rotating grinding media for the fine grinding of coal, rocks and earth with a multi-row arrangement of the balls, characterized in that that the rotating, each provided with an upper and lower grinding track, by means of a double cardan shaft angularly drivable middle grinding rings with the grinding balls in the manner of a double angular contact ball bearing are each supported and centered on a stationary grinding ring, whereby the drive shaft is protected from axial forces, which result from the grinding pressure, is relieved and the helix angle of the balls between 90 ° and 45 °, and the grinding pressure is applied between two fixed grinding rings. 2. Roller mill according to claim 1, characterized in that the helix angle of the grinding balls of the lower Grinding process is different from that of the upper one, with all the balls involved in the grinding work have the same diameter. 3. Roller mill according to claims 1 and 2, characterized in that material feed rings that loosely rest on the grinding balls and rotate with them, being carried along by the friction. 4. Roller mill according to claims 1 to 3, characterized in that between the non-rotating grinding rings There are working cylinders equipped with (gas) springs which generate the grinding pressure. 030041/0298