GB2121138A - A chain strand for conveyor and plough chains - Google Patents

Abstract

A chain strand is provided having identically formed and interengaging chain links, mainly intended for conveyor and plough chains used in underground mining and tunnelling equipment. The interengaging ends (7) of the chain links (2, 3, 4) are designed so as to extend at right angles to the link legs (6). The ends extend transversely beyond the legs and are convexly curved at their end surfaces. <IMAGE>

Description

SPECIFICATION A chain strand for conveyor and plough chains The invention relates to a chain strand of identically formed and interengaging chain links, mainly intended for conveyor and plough chains used in underground mining and tunnelling equipment.

Such chain strands provided with identically formed and interengaging chain links are used for a wide variety of purposes in underground mining.

These chain strands are particularly subjected to wear when used for haulage and extraction work because, in conveyors, they drag along the bottom plate or the conveyor bottom and, in ploughing equipment, they drag in the guideways and are thus subjected to considerable wear, due to the continuous and partly intermittent contact therewith. In recent years, the development of conveyor and plough chains has only been to the effect that the dimensions thereof were made larger and larger, namely from 1 8 x 64, 19 x 64.5,22 x 86,26 x 92,30 x 108 to at present 34 x 126.

However, the development in the direction of ever increasing dimensions of the chain strands is unsatisfactory because, although the service life of the chains is prolonged by larger dimensioning, the problems remain the same and become even greater than hitherto. These problems relate, in particular, to the difficult force introduction into the chain strand, the dimensions of the sprocket wheels, the wear of the chain links, the increase in the hardening of the chain at different points and the wear that continues to arise and particularly affects the supporting cross-section to a considerable extent.

This wear mainly occurs on the bearing surfaces of the chain in the direction of the conveyor and of the plough chain in the direction of the guide elements. The chain strands lose a portion of their cross-section that is not inconsiderable so that the supporting crosssection is gradually reduced. There furthermore arise in these zones undesirable hardness increases by way of the formation of abrasive martensite, causing the work capacity of the chain strand to be reduced. Moreover, this is where the first signs or starting points of stress corrosion appear, which frequently necessitate the premature elimination of such chain strands.

The force introduction is effected via the sprocket wheels, the contact between the sprocket wheel and the round link chain only being possible punctually, which entails very high surface pressures in these punctual points of contact. Chains which have been in use for some considerable time therefore have marked indentations in the link curvatures from the engagement of the sprocket wheel. These force introduction points are an important weak spot of round link chains and also limit the life of such chain strands. It is furthermore disadvantageous that wear phenomena naturally also occur on the sprocket wheels, so that these have to be exchanged frequently.Over and above this, the sprocket wheels are additionally stressed due to the fact that, on account of the chain link shape, there arise high lateral forces which have to be compensated for and absorbed by an appropriate design of the sprocket wheel.

An object of the invention is to increase the service life of conveyor and plough chains without any change in the nominal size thereof, that is to say without any larger dimensioning thereof, and to optimise the force introduction into the chain strand via the sprocket wheel.

According to the invention, this problem is solved in that the front ends of the chain links are designed so as to extend at right angles to the link legs, the ends extending transversely beyond the link legs and having convexly curved end surfaces.

Such a chain link can be combined with other identically designed chain links so as to form a chain strand, as hitherto, but there being advantageously specified, due to the convex design of the outside of the chain link, wearing points which render possible a protracted wear without affecting the supporting cross-section of the respective chain link. Over and above this, due to the right-angled design of the front ends of the chain link, the hitherto punctual stress exerted on the chain strand in the sprocket wheel has been replaced by a line contact, which results in a substantial reduction of the surface pressure. By this means, there is prevented not only the wear of the chain links in the sprocket wheel but also a wear of the sprocket wheel; at least, it is considerably reduced.As a result, the service life of the chain strands and that of the sprocket wheel is considerably increased, the lateral forces, which arose until now, being completely avoided in an advantageous manner, so that the construction of the sprocket wheel can be considerably simplified.

Further, a favourable contact of the respective chain link with the conveyor bottom, and consequently a uniform wear of all parts which are subjected to wear, is ensured in that the convexly curved ends of the front ends and the link legs are so designed that they result in a concave outside of the chain link, there being specified in both end zones of the chain link bearing surfaces for sliding on the conveyor bottom of the guide elements. In addition to the front ends of the respective chain link which have been designed so as to be further advanced and thus convexly curved, there are thus given additional lugs in the direction of the link legs which ensure a proper bearing surface for the chain link in both end zones. There are thus formed not only punctual frictional surfaces but rather linear or areal bearing surfaces which stabilise the respective chain link.Consequently, the wear is distributed over a larger area and the quantity of material which has to be worn before it is possible for a reduction of the supporting crosssection of the respective chain link to occur is increased.

Preferably an optimum surface or wearing zone is specified in that the radius of the concave outside is chosen so as to correspond to the inside length of the chain links. At the same time, the already mentioned positional stabilisation of the individual chain link in the chain strand is improved. The loss of material arising due to the wearing surfaces is inconsiderable with regard to the service life of the chain link because it occurs in zones which do not reduce the supporting cross-section of the chain link and because it is possible for abrasive martensite hardening and stress corrosion to occur here without any risk to the chain link proper.

The inside design of the chain link according to the invention is similar to that of the hitherto known chain links. According to one development, provision has been made for each chain link to have, on the inside, recesses which receive the front ends and which are designed so as to be open in the direction of the link legs. By this means, there is left to the individual chain link sufficient freedom of movement in the respective adjacent chain link in both directions, so that the chain strand can be easily transported and fitted.

This also allows shocks and similar loads to be easily absorbed, without any damage, such as deformation, occurring.

The chain links joined to form a chain strand are as a rule produced from a round-bar steel which is cut to the appropriate size and then bent to form a chain link. The required configurations at the front ends and the adjoining zones of the link legs respectively can be specified on the finished chain link by upsetting or similar configurations, or else already on the original wire rod or cut-to-size piece. According to the invention, provision has been made in this regard for the weld junctions of the chain links to be exactly in the centre of one of the link legs, there being also provided the possibility of producing a chain link from two parts, when the weld junctions are then intended to be somewhat displaced relative to one another in the zone of the link legs.

Such chain strands are used in scraper conveyors and in ploughing equipment. Due to the configuration of the individual chain links, an appropriate adaptation of the scraper conveyors and the ploughing equipment is necessary.

According to the invention, a scraper conveyor provided with a conveyor chain, which is equipped with flights, conveyor pans, on the bottom of which the conveyor chain is moved in a dragging manner, and sprocket wheels, which are provided at the ends and have crown gears receiving and guiding the conveyor chain, is so designed that the crown gears of the sprocket wheels have teeth with straight edges but otherwise have a troughing which receives the front ends of the chain strand. By this means a considerable simplification of the sprocket wheels is possible but, in particular, the force introduction is linear in co-ordination with the corresponding front ends of the chain links, so that the crown gear or the sprocket wheel no longer has to absorb any lateral forces.

According to another feature of the invention, a force introduction that is confined to or directed at the supporting parts of the chain links is 'ensured in that the edge width of the teeth of the sprocket wheel has been chosen so as to correspond to the diameter of the link legs. Consequently, the chain link edge zones subjected to wear are kept clear of the direct force introduction, which is advantageous, inter alia, because with wear occurring in these zones, the force introduction would otherwise be respectively displaced in the direction of the centre of the chain link, that is to say would be changed over the service life.

Further according to the invention, a uniform and effective guidance of the upright chain links, too, is ensured in that there are provided in the internal flanks of the crown gears recesses, into which the convexly curved ends of the front ends of the chain links can be inserted.

The invention is particularly distinguished in that, during wear of the chain, the convex design of the outside of the chain link causes the supporting cross-section in the centre of the chain link to be initially kept completely free of any wear.

The spherical design at the front ends of the chain link presents sufficient wearing material for a long time of operation. This loss of material is immaterial for the service life of the chain link because it occurs in zones which do not reduce the supporting cross-section of the chain link. The force introduction into the chain strand takes place linearly in the chain link according to the invention and the scraper conveyor. The thereby considerably reduced surface pressure leads to a further reduction of wear along with a better force introduction. The stress on the chain links and, in particular, on the sprocket wheels is additionally reduced in that the sprocket wheel no longer has to absorb any lateral forces.

Further details and advantages of the subject matter of the invention will emerge from the following description with reference to the accompanying drawings, in which a preferred exemplified embodiment has been illustrated with the necessary details and individual parts. In the drawings: FIGURE 1 shows a chain strand in a section, FIGURE 2 shows a chain strand which is used as a centre chain in a scraper conveyor, FIGURE 3 shows an individual chain link, and FIGURE 4 shows a sprocket wheel in a side view.

The chain strand 1 shown in a section in Fig. 1 consists of several identically formed chain links 2, 3, 4. These chain links engage one within the other, freedom of movement being given to them in the horizontal direction and the possibility being provided of swivelling a chain link while it lies in the respective adjacent chain link.

The link legs 6 of the chain links 2, 3, 4 are wire or bar sections, i.e. rounds. The front ends 7 are also round or circular, their edges extending however at right angles to the link legs 6. There is by this means clearly provided a straight edge which renders possible a linear force transmission during the introduction into the sprocket wheel and during the force introduction.

The ends 8 of the front ends 7 have been taken beyond the link legs and are convexly curved. By this means, there is formed a wearing zone which protects the supporting cross-section of the link legs 6 from any wear for a long time, and thus from any weakening. This outside 10, which is present in the end zones 12, 13 of the chain link, simultaneously serves as a bearing surface and for positional stabilisation when the chain strand is pulled over the conveyor bottom 18. The conveyor bottom 18 is shown as a single line in Fig. 1 so as to clearly illustrate the size of the bearing surface of the individual chain links in the two end zones 12,13.

Each chain link has, on the inside, recesses 11 which receive the front ends or front parts of the adjacent chain link 2, 3, 4. These recesses are designed so as to be open in the direction of the link legs so that the individual chain links can be displaced within one another.

Fig. 2 shows a chain strand 1 in use, that is to say as a centre chain in a scraper conveyor 1 7.

The profile of the scraper conveyor 1 7 is such that the individual flights 1 9 are laterally effectively guided and stabilised, so that the centrally laid chain strand 1 actually does not have to assume any stabilising and supporting functions. To this end, there serve chain holders which are given for this purpose a suitable configuration, that is to say one that has a large base. On account of the special design of the chain strand 1, such chain holders are not necessary because the chain strand 1 can itself assume supporting functions, as Fig. 2 clearly illustrates.

Fig. 3 shows a chain link in a top view, the supporting and wear assuming surfaces in the end zones 12, 13 clearly emerging here, too. In the centre of the link leg 6, there has been indicated the weld junction 1 5.

Fig. 4 finally shows a sprocket wheel 20 with a crown gear 21. This crown gear 21 has teeth 22 with straight edges 23. This design of the edges 23, which is favourable for the force introduction or force transmission, is rendered possible by the special configuration of the chain links 2, 3, 4.

When the chain links pass through the sprocket wheel, the respective chain link lies in the troughing 24. The upright chain link actually lies outside the respective teeth 22 with the end zones 12, 13. However, on account of Ale circular movement executed by the sprocket wheel, the front end 7 of the respective chain link 2, 3, 4 comes into contact with the tooth, for which purpose the internal flanks 26 of the teeth 22 have recesses 27.

Claims (10)

1. A chain strand of identically formed and interengaging chain links, mainly intended for conveyor and plough chains used in underground mining and tunnelling equipment, characterised in that the front ends (7) of the chain links (2, 3, 4) are designed so as to extend at right angles to the link legs (6), the ends extending transversely beyond the link legs and having convexly curved end surfaces.

2. A chain strand as claimed in Claim 1, characterised in that the convexly curved ends (8) of the front ends (7) and the link legs (6) are designed so that there comes about a concave outside (10) of the chain link (2, 3, 4), there being specified in both end zones (12, 13) of the chain link bearing surfaces for sliding on the conveyor bottom (18) or on the guide elements.

3. A chain strand as claimed in Claim 2, characterised in that the radius of the concave outside (10) has been chosen so as to correspond to the internal length of the chain links (2, 3, 4).

4. A chain strand as claimed in Claim 1, characterised in that each chain link (2, 3, 4) has, on the inside, recesses (11) which receive the front ends (7) and which are designed so as to be open in the direction of the link legs (6).

5. A chain strand as claimed in Claim 1, characterised in that the weld junctions (1 5) of the chain links (2, 3, 4) are located exactly in the centre of one of the link legs (6).

6. A scraper conveyor provided with a conveyor chain, which is equipped with flights, conveyor pans, on the bottom of which the conveyor chain is moved in a dragging manner, and with sprocket wheels, which are provided at the ends and have crown gears receiving and guiding the conveyor chain, characterised in that the crown gears (21) of the sprocket wheels (20) have teeth (22) with straight edges (23) but otherwise have a troughing (24) which receives the front ends (7) of the chain strand (1).

7. A scraper conveyor as claimed in Claim 6, characterised in that the edge width of the teeth (22) of the sprocket wheel (20) has been chosen so as to correspond to the diameter of the link legs (6).

8. A scraper conveyor as claimed in Claim 6, characterised in that in the internal flanks (26) of the crown gears (21) there are provided recesses (27), into which the convexly curved ends of the front ends (7) of the chain links (2, 3, 4) can be placed.

9. A chain strand substantially as described by way of example with reference to the accompanying drawings.

10. A scraper conveyor substantially as described by way of example with reference to the accompanying drawings.