GB2127520A - Driving chain - Google Patents

Abstract

A driving chain, having two sets of interconnected chain links which lie in mutually perpendicular planes, the links of one set alternating with the links of the other set, has each link (12, 13, 14) of at least one set of links formed so that each of its ends (15, 16 and 17, 18) has a generally larger cross-section than the cross-section of the link intermediate its ends to reduce elongation thereof in use. <IMAGE>

Description

SPECIFICATION Driving chain This invention relates to a chain which is intended for use in the transmission of a driving force over sprocket wheels or chain drums or drive chains or the like, the chain having two sets of chain links which lie in mutually perpendicular planes, the links of one set alternating with the links of the other set.

Conventional round-link chains consist of identical chain links. Such chains are spatially flexible. The also require only a moderate diameter in the chain-drum for the transmission of high forces and are therefore eminently suited for the transmission of driving power in the confined spaces of underground mining. High precision and close tolerances in the manufacture of the chain, together with calibration and a particularly closely toleranced configuration of the link-pockets of the chain drive wheels from which the external driving force is transmitted to one set of chain links and the essential characteristics to be observed in order to enable the efficient transmission of high forces and drive performances through such round-link chain drives in the mining industry where they may be used for example in coalshaving machines and chain-scraper-conveyors.

The aforementioned high advanced technological development of round-link chains and associated drive wheels affords a satisfactory and largely problem-free drive transmission for as long as the chains and the chain wheels are in a new or unworn condition.

However, after a longer period of service, considerable problems tend to occur which are of a basic character and which as clearly demonstrated by more than 25 years of practical experience cannot be remedied by constructional provisions and improved materials. The geometrical shape of the links changes and very soon it no longer corresponds to the very close tolerances which must be observed between chain and chain wheel for the transmission of high power outputs.

Thus, in coal-shaving machines and chain scraper conveyors it was observed that in course of time the chains were subject to elongations which must be ascribed to continual repetitive stress application, and further elongations and configurational deformations in the affected chain links may be caused by no means infrequently occurring blockages, particularly if these occur in the vicinity of the driving stations. Such elongations are predominantly due to variations in the radiussed regions of the chain links, that is to say in those regions of the chains where the force is transmitted through the chain links to the chain as a whole. Due to such change of radii the engagement surface area of the chains in the pockets of the chain wheels is extremely reduced thus giving rise to overloads and further wear on chains and chain wheels.Moreover, elongation of the chain links also changes the chain pitch with the result that the chain no longer mates with the co-acting chain wheels. As a matter of fact this condition often occurs after comparatively short service times so that chains and chain wheels must be replaced, which entails a great deal of work. A replacement of either only the chains or only the chain wheels could in no way be adequate because deformed or worn chains simply do not mate with new chain wheels and vice versa.

All of the aforedescribed problems arise basically from the fact that bending resistance of the radiussed ends of the links and maximum theoretically possible force-transmission surface area are predetermined by the wire gauge of the chain links.

German patent specification OS 22 47 300 describes a round-link chain in which the horizontal chain links are provided at both ends thereof with outwardly projecting width-enlarged portions which represent a thrust face for the teeth of the chain-wheel. Due to the enlargement of the thrust faces a corresponding reduction is obtained in specific pressure per unit area.

However, whilst in this known chain the area of mutual contact between one set of chain links and the chain wheel is increased, the cross-sections in the region of these chain links which are subject to bending loads are by no means increased by this provision. This means that this known chain is also subject to the same degree of elongation as a chain constiting exclusively of round-steel links.

Furthermore, the radii of the thrust faces on the aforesaid chain links are equal to the radius of the chain-wire -- which limits the size of the thrust face. Chain elongation and therefore modification of chain pitch will therefore result in higher wear of a conventional round link chain as well as of a chain of the kind described in German OS 22 47 300 and associated chain wheel because the pitch of the chain wheel does not change correspondingly.

It is the aim of the present invention to provide a chain of the kind specified in which elongation of the links and therefore modification of the chain pitch are inhibited. Furthermore, the invention aims to improve the meshing, or running-in properties of the driven chain links relative to the driving wheel and at the same time to increase the size of the force-transmitting surfacd area between the driven chain links and the sprocket teeth of the chain wheel. According to the invention these aims are achieved due to the fact that the driven chain links are made greater in cross-section in the region of their ends than in the region of their medial portions.

These provisions achieve such an improvement in the conditions of force transmission from sprocket wheel to chain that the theoretically possible force-transmission face areas are increased, whilst elongation is reduced even in the event of unforeseen sudden blockages, and thus actual transmission area and service life of the chain are substantially increased. These results are essentially due to the improved configuration of the chain links to which the force is transmitted by the chain-driving wheels.

Due to the larger cross-section of the end regions of the driven chain links relative to the medial regions the risk of bending deformation of the end region of the chain link under high or excessive load application is ruled out. The invention deliberately abandons the constant cross-section of conventional round link chains which resulted from the practice of manufacturing the individual chain links from wire stock. The end region of the chain links to which the driving force is transmitted has greater bending resistance due to its configuration and is therefore considerably less senstivie to elongation, even when subjected to sudden peak loads caused by blocking of the chain drive.

According to a further characteristic, the invention provides that the driven chain link ends should extend substantially rectilinearly over at least the width of the chain link in a transverse direction relative to the length of the chain. Due to this provision the frontal end face of the link ends is essentially enlarged so that larger engagement and force transmission areas are available for force transmission when the link runs into the sprocket wheel and consequently undue wear is virtually precluded.

In further development of the invention the link ends may be enlarged beyond the width of the medial part of the chain link. Again this provision secures an increase in the size of transmission faces between chain wheel and chain.

The thrust faces are also enlarged by increasing the thickness of the end region as well as enlarging its width.

It is advisable to provide conical recesses in the end region of the chain link. This ensures the spatial flexibility of adjacent chain links. A chain consisting of links of this kind can be turned through goc after friction wear at the ends which in practice results in a chain which has all the advantages of a new chain. This is due to the fact that in a chain according to this invention the end regions of the chain link are so strongly designed that such far-reaching elongations as would destroy pitch mating between chain and sprocket wheel are virtually ruled out.

The chain links may be produced by casting, forging or any similar process.

Alternatively the chain links may be produced by welding together at the flanks two chain link halves which were previously produced by chipless, i.e. non-cutting deformation. In that case it is recommended to join the two half-links by electric butt-resistance- or flash-butt welding methods.

According to a further characteristic of the invention the chain may be executed such that only the driven links have end regions as above described whilst the intervening links are roundsteel links. In such a chain the round-steel links may be longer than the other chain links.

Conveniently the ends of the drive chain links are co-ordinated with the teeth of the sprocket wheel in such a way that in the presence of chain elongation the actual force transmission in the sprocket wheel will take place on a pitch circle of correspondingly larger diameter.

This provision ensures that perfect force transmission will be maintained even with a chain consisting of alternate round steel links and links which are provided with wide and flat reinforced end regions. This effect is obtained particularly due to the fact that the driving force will be transmitted at a further outwardly situated point of the sprocket tooth or link pocket whereby the pitch circle diameter is slightly increased. In other words, chain pitch and sprocket pitch mutually correspond in such a way that an increased chain pitch due to elongation will be automatically compensated by passing over to a greater radial track of the sprocket wheel and thereby restoring the identical, or mating pitch of chain and chain wheel.

Lastly, with chains which incorporate chain links with end regions as above described it is of great advantage to use driving chains instead of sprocket wheels.

The invention is hereinafter more particularly described with reference to some examples of embodiments illustrated in the drawings in which: Figure 1 is a plan view of a chain according to a first embodiment of the invention.

Figure 2 is a plan view of a chain according to a second embodiment of the invention, Figure 3 shows a chain according to a third embodiment of the invention, Figure 4 is a plan view of a fourth embodiment, Figure 5 is a side view of the chain shown in Figure 4, Figure 6 shows a chain according to Figures 4 and 5 in engagement with a sprocket wheel, and Figure 7 shows the chain according to Figures 4 and 5 in engagement with a short revolving drive chain.

Figure 1 shows a chain in which the (as shown) vertical set of chain links 10, 11 are round-steel links whereas the (as shown) horizontal set of chain links 1 2, 13, 14 (which form the driven links) are provided at the front and rear part thereof with a blunt region 1 5, 16 and 17, 1 8. In the gaps between the horizontal chain links 12 and 13 engage the driver teeth 19, 20 of a sprocket wheel, not completely shown in Figure 1.

In the illustrated example, the tooth flanks 21, 22 of said driver teeth 19, 20 extend transversely of the length of the chain and so do the thrust faces 23, of the associated regions 17, 18 respectively. In other words, faces 21 and 23 as well as 22 and 24 are mutually parallel thereby presenting a comparatively large surface area for the transmission of force from the teeth 1 9, 20 to the horizontal chain link 1 3. Due to such force transmission over a large surface area, the geometrical form and size of the transmission faces 21,22 and 23,24 will not alter even in chains which have been subjected to longer periods of service and peak loads.In the embodiment according to Figure 1 the pitches of the horizontal chain links 12, 13, 14 and of the vertical chain links 10, 11, are equal. Arrow a shows the direction of chain travel. In an alternative construction, the "vertical" set of chain links may each be formed in a manner similar to the links of the "horizontal" chain set.

The chain shown in Figure 2 corresponds substantially to that of Figure 1 except for these two differences that the ends 1 7, 1 8 and 1 5, 1 6 of the links 12, 13 and 14 according to Figure 2 are somewhat wider than the ends of the corresponding links of the chain seen in Figure 1 and in that the width of such links intermediate their ends is less than the width of the corresponding links of the chain seen in Figure 1.

The pitches of the horizontal chain links 12, 1 3, 14 and of the vertical chain links 10, 11 are also equal in this embodiment.

Figure 3 shows a chain consisting of comparatively long vertical chain links 25, 26 which are mutually connected by comparatively short horizontal chain links 27. The horizontal chain links 27 have relatively wide end regions 28, 29 and 30, 31 and moreover medial parts 32, 33 therebetween. In this chain the pitches of the horizontal chain links 27 and the vertical chain links 25, 26 are no longer equal.

The chain shown in Figures 4 and 5 consists of vertical chain links 34, 35 which are mutually connected by horizontal chain links 36 with a constricted waist region 37. In this embodiment the chain link ends 38 39 and 40, 41 are not only relatively wide as will be seen from Figure 4, but are further reinforced by thickened regions 42, 43 and 44, 45 so that due to the provision of these thickened regions 42, 43, 44, 45 the teeth 19, 20 of the sprocket wheel find a still larger engagement surface area on the ends 38, 39, and 40, 41. These thickened regions 42, 43, 44, 45 have tapered recesses 46, 47, 48, 49 for the vertical chain links 34,35 in order to preserve flexibility of this chain.

The sprocket wheel 50 shown in Figure 6 comprises seven sprocket teeth 51, 52, 53, 54, 55, 56 and 57 which each comprise a pair of juxtaposed tooth portions. On rotation of sprocket wheel 50 in the direction of arrow b the horizontal chain link 58 with its two adjacent vertical chain links 59 and 60 runs into mesh with sprocket wheel 50 and is carried along by the latter along a distance of 1 800 whereafter it leaves the sprocket wheel 50 at tooth 56. Between every pair of juxtaposed teeth on the sprocket wheel, for example between tooth pair 52, there is provided a hollow 61 for the vertical chain link 60.

Figure 7 shows a short endless chain band drive 62 consisting of an articulated link chain which revolves between two drums 63, 64. The individual links 65 of the chain band also have identically formed driver teeth 66 and between the individual chain links there are hinge joints 67.

When the drum 63 rotates in the direction of arrow d and drum 64 rotates in the direction of arrow e the driving chain 62 and with it the driven chain will travel in the direction of arrow c. For drive transmission to the chain the driver theeth 66 in the region of drum 63 engage in the gap 68 between two adjacent horizontal chain links 69, 70. This positive engagement is sustained until the driver teeth 66 of chain 62 slip out of the gap 71 between the two adjacent horizontal chain links 72, 73 in the region of drum 64.

Claims (12)

1. A driving chain for use with sprocket wheels, chain drums or chain-band drives and having two sets of chain links which lie in mutually perpendicular planes, the links of one set alternating with the links of the other set, characterised in that each link of at least one set of chain links is formed so that each of its ends has a larger cross-section than the cross-section of its flanks.

2. A chain according to Claim 1, characterised in that said ends of the links of said one set of links extend substantially rectilinearly transversely of the length of the chain over at least the width of the chain link.

3. A chain according to Claim 1 or Claim 2, characterised in that said chain link ends extend outwardly beyond the width of the central portion of the chain link.

4. A chain according to any one of Claims 1 to 3, characterised in that said chain link ends besides being enlarged in width are also provided with a thickened region.

5. A chain according to any one of Claims 1 to 4, characterised in that tapered recesses are provided in the region of said chain link ends.

6. A chain according to any one of Claims 1 to 5, characterised in that the chain links are made by casting or forging.

7. A chain according to any one of Claims 1 to 5, characterised in that the chain links are produced by welding together along the flanks two half links produced by a non-cutting deformation.

8. A chain according to Claim 7, characterised in that the half links are mutually joined by electric butt-resistance or flash-welding.

9. A chain according to any one of Claims 1 to 8, characterised in that only one set of chain links are provided with relatively wide end regions, the intervening chain links being round-steel links.

10. A chain according to Claim 9, characterised in that the round steel links are longer than the chain links of the other set of links.

11. A chain according to any one of Claims 1 to 10, characterised in that said end regions of the chain links are so co-ordinated with the teeth of the associated sprocket wheel that in use and in the presence of chain elongation, force transmission from the sprocket wheel takes place on a pitch circle of correspondingly larger diameter.

12. A chain drive assembly including a chain formed in accordance with any one of Claims 1 to 11, characterised in that a chain-band drive drives the chain.

1 3. A driving chain substantially as hereinbefore described with reference to and as shown in Figure 1, or Figure 2, or Figure 3, or Figure 4 of the accompanying drawings.