EP0804965B1 - Milling surface - Google Patents

Description

The present invention relates to a track for shredders consisting of several segments supported by a rotary table and forming a double circular raceway running under rollers grinding to grind material spilled on the runway.

A grinder of the kind targeted by the present invention is, for example, described in document FR-A-2262476. The slopes, as well those to simple raceway, like that shown in document BE-A-897937, than those with double raceway, are generally made up of separate neighborhoods or segments juxtaposed, which allows easier handling of these items of limited weight because it requires know that the total weight of an entire track can be of the order of a few tens of tonnes. In addition, in the event of accidental deterioration of a track segment, it can be replaced individually without need to replace the whole track.

The major problem with grinder tracks is wear. As a result of the abrasive nature of the material to be ground, the segments are, in fact, exposed to rapid and intense wear and must be made of cast iron very hard chrome. On the other hand, the segments must be machined very precise to be fixed correctly on the grinder table and protect this against any deterioration likely to occur during service. Since these requirements are not mutually compatible, the machining a chrome cast iron track is very difficult and very expensive.

The wear of the double track tracks is, moreover, irregular as the inner raceway wears more faster than the outer raceway. Profile shapes the wear of the raceways are also different which results in differences in the grinding efficiency of a rolling relative to each other and reduces the efficiency of the mill. Of a in general, it is the state of wear of the inner race which is crucial for the replacement of segments and it is often necessary to replace a track or segment while its region forming the outer raceway could still serve some time.

The purpose of the present invention is to provide a new track for shredders which overcomes these drawbacks, in particular provide a track with better resistance to wear and a track which exhibits more uniform wear.

To achieve this objective, the invention proposes a path for grinders of the kind described in the preamble which has the characteristics of claim 1.

Thanks to the design of the added wear segments, it is it is possible to choose harder and more resistant materials for these wear without being limited in the choice by the need for machining accurate from the ground up. So we can not only predict for the segments wear of ferrous alloys such as chromium cast iron, but also composite parts with metal matrix and inserts extremely hard, for example in various ceramics.

Similarly, it is possible to choose for the sole a steel easily machinable since the sole is not subject to wear grinding. The sole can therefore be machined under optimal conditions to be fixed correctly on the rotary table which must remain in perfect state.

The wear segments can be fixed on the sole using screws and clamps.

The edges of the sole may have bevelled parts forming dovetail fasteners with the wear segments.

In the event of wear, simply replace the added wear segments, the sole can remain in place. The fastenings of these segments by screws and clamps allow easy and easy replacement.

Since the sole can stay in place it protects the table effectively against possible impacts with the segments wear when replacing them.

In this case, the inner segments and the outer segments can be replaced separately and the outer segment, in particular, can stay in place until the raceway exterior is completely worn out. It is also possible to choose a harder material for the inner segments in order to ensure a uniform wear of the two raceways.

In general, the invention offers the possibility of choosing different materials for each of the wear segments and to regularize the general wear profile by choosing a harder material where the track wears out the most and makes the wear profile more uniform, which has a great influence on the performance of the mill.

• la Figure 1 représente schématiquement une coupe radiale à travers une piste annulaire selon la présente invention et
• la Figure 2 représente schématiquement une coupe radiale à travers la semelle.

Other particularities of the invention will emerge from the detailed description of a preferred embodiment presented below, by way of illustration, with reference to the appended figures in which:

• FIG. 1 schematically represents a radial section through an annular track according to the present invention and
• Figure 2 schematically shows a radial section through the sole.

The track shown in Figure 1 and generally designated by the reference 10 is fixed on a rotary annular table not shown. She has two annular raceways on its upper face concentric, of concave section, more precisely a raceway interior 12 and an exterior raceway 14 which evolve in underside of two pairs of grinding rollers not shown on the surface of convex bearing.

The two raceways 12 and 14 are defined in a series of internal wear segments 16 respectively a series of segments external wear 18, these segments being made of very resistant material to wear. The different segments are fixed in housings defined in a sole 20 (see also figure 2) which can also be segmented and which is made in treated steel to obtain good mechanical properties and to be easily machinable.

The sole 20 has a flat base 22 with an edge inner 24 and an outer edge 26 delimiting with a rib protruding median 28 in an arc of a circle the locations of the segments wear 16 and 18. The interior and exterior edges 24 and 26 preferably have inclined corners 30 respectively 32 cooperating with corresponding bevelled corners of segments 16 and 18 to define solid dovetail fasteners wear segments.

Wear segments may have, on their surface lower, cells 34 into which pins 36 penetrate through the sole 20 to ensure correct positioning of the segments when placing these and prevent any relative displacement of the wear segments relative to the sole, under the action of the engine torque transmitted by the sole and the segments to the bed of material to be ground and to the rollers.

The fixing and tightening of segments 16 and 18 can be secured by screws 38 and clamps 40 in the middle region and by dovetail housing 30 and 32 on the periphery of the sole 20.

If the invention has been described in detail with reference to Figures 1 and 2 in the context of its advantageous application to a track for two raceways, it should be noted that it is not limited to this application and that it also brings many advantages to tracks with a single raceway.

Claims (5)

1. Track for mills supported by a turntable and forming two concentric circular runway paths moving beneath milling rollers in order to mill the material tipped out onto the track, characterized in that the two runway paths are formed by the upper surfaces a series of inner wearing segments (16) and a series of outer wearing segments (18) removably secured to a supporting (20) sole made of machineable steel having a circular projecting middle rib (28) and outer (26) and inner edges (24) defining with said rib (28) annular housings for outer segments (18) and the inner segments (16) respectively.
2. Track according to Claim 1, characterized in that the wearing segments are fixed to the sole (20) using screws (38, 42) and clamping claws (40).
3. Track according the Claim 1, characterized in that the edges of the sole (20) have bevelled parts (30, 32) forming dovetails for attachment to the wearing segments.
4. Track according to any one of Claims 1 to 3 characterized in that the wearing segments are made of chromium alloy cast iron.
5. Track according to any one of Claims 1 to 3 characterized in that the wearing segments are composite components with a metallic matrix or with ceramic inserts with a high resistance to the wear.

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