WO1991001261A1

WO1991001261A1 - A chain link for a laterally flexible conveyor chain

Info

Publication number: WO1991001261A1
Application number: PCT/DK1990/000190
Authority: WO
Inventors: Jørgen DRÆBEL
Original assignee: Draebel Joergen
Priority date: 1989-07-20
Filing date: 1990-07-19
Publication date: 1991-02-07
Also published as: AU6172690A; DK359789A; DK359789D0; DK162348B; DK162348C

Abstract

A chain link (12) for a laterally flexible conveyor chain (2) has a first and a second row of mutually parallel eye parts (13, 15) extending in transverse direction and having shaft openings (14 and 16, respectively) for the shafts (20) by which the chain (2) is assembled. The eye parts (13, 15) in each row are positioned with a mutual spacing in transverse direction which is greater than their width, and each of them is connected with the two most adjacent eye parts in the second row by means of two connecting members (17), which together form a V and each of which has a longitudinal slot (18) extending from the respective shaft opening and having the same height as said opening. Lateral projections (21, 22, 23) are provided on both sides of at least some of the eye parts (13, 15) in each row, said lateral projections extending within a region which is defined by the planes formed by the flush upper and lower sides, respectively, of the slots (18). Each of these lateral projections (21, 22, 23) has such an extent in transverse direction that it will be disposed at least in the vicinity of the opposed lateral projection on the adjacent eye part positioned on the same side of the common shaft (20), when the respective chain links (12) are in mounted position in a substantially stretched and straight conveyor chain (2).

Description

A chain link for a laterally flexible conveyor chain

The invention concerns a chain link for a laterally flexible conveyor chain, comprising a first row of eye parts which are preferably equidistantly spaced in trans¬ verse direction and have aligned openings to receive a chain shaft; a second row of eye parts which are prefer¬ ably positioned centrally between the first row of eye parts at a parallel-displaced distance from said first row of eye parts corresponding to the chain pitch and have aligned openings to receive a second chain shaft; as well as two connecting members which are associated with each eye part and preferably have the same height as the eye parts and serve to connect, in V-shape, the respective eye part with the two most adjacent eye parts in the second row of eye parts; the width of each eye part being smaller than the mutual spacing between eye parts in the same row; longitudinal slots being provided transversely through the connecting members, said slots being mutually flush in transverse direction with a height substantially corres¬ ponding to the diameter of the openings of the eye parts and terminating in one row of said openings.

Conveyor chains composed of chain links of this type are extensively used for purposes where it is necessary that the chain traverses relatively sharp curves, since such chains have precisely considerable flexibility in a hori¬ zontal plane because of the special V-shape of the links, enabling the links to move into one another during bend¬ ing, while the shafts slide in the slots. When passing through a curve this mutual movement between the links and between these and the shafts, however, will cause the overall pull in the chain to be transferred solely via the two eye parts which are disposed outermost in the curve on each shaft and belong to their respective chain links, and since these eye parts are simultaneously displaced axially away from each other during the mutual movement of the re¬ spective chain links, the outer ends of the shafts are subjected to a horizontal torque swinging the shafts out of their correct position. However, the chain links have no means to return them to their normal position once the curve has been traversed, so that the shafts are not sub¬ jected to any form of action that might cause them to re- assume their correct position at right angles to the feed direction. This is unfortunate for esthetic reasons, since it shows that the chain does not work in the manner nor¬ mally expected, and it may moreover be difficult, if not impossible, to obtain due mesh between the chain links and the chain wheels, the necessary condition being non-exist- ing, viz. that the chain is stretched and the shafts are perpendicular to the feed direction. To this should be added that the V-shape of the chain links entails that there is a not insignificant gap between the eye parts on the same shaft, so that the shaft is subjected to both shear stresses and considerable bending stresses which may cause breaks or deformation of the shaft, in particular when it consists of such a relatively weak material as plastics, which, however, is frequently used as a material for conveyor chain shafts.

The object of the invention is to provide a chain link of the type mentioned in the opening paragraph for a late¬ rally flexible conveyor chain, whose shafts are subjected to considerable smaller combined loads than known in the past and are automatically aligned to correct position at right angles to the feed direction when the chain leaves a curve.

This is obtained in that the chain link of the invention is characterized in that lateral projections are provided on each side of at least some of the eye parts in each row, said lateral projections extending within a region which is defined by the planes formed by the aligned upper and lower sides, respectively, of the slots, and that each of said lateral projections has such an extent in the transverse direction that it is disposed at least in the vicinity of the opposed lateral projection on the adjacent eye part positioned on the same side of the common shaft when the respective chain link is in mounted position in a substantially stretched and straight conveyor chain. This entails that when the chain leaves a curve the chain links automatically assume their normal mutual central positions without additionally being able to move axially with re¬ spect to each other, and the shafts are therefore pulled into their proper position at right angles to the feed direction. This is achieved without the chain losing its great flexibility since the lateral projections are re¬ ceived in the slots during bending.

According to the invention, the lateral projections may have a thickness which is just as great as or slightly smaller than the height of the slots, so that the lateral projections advantageously obtain the greatest possible strength.

Moreover, according to the invention, each lateral projec¬ tion may be formed with a shaft carrier face forming a flush elongation of the part of the internal cylinder face of the adjoining shaft opening which is disposed in the thickness extent of the lateral projection. This elimi- nates the gap between the eye parts on the same shaft which is now by and large only subjected to displacement forces.

Further, according to the invention, each lateral projec- tion may have a side edge extending from the carrier face of the lateral projection and forming an angle with it. and the side edges on at least the innermost lateral pro¬ jection of the pair of lateral projections associated with an eye part may diverge in a direction toward the axis of the shaft openings. Therefore, the respectively adjacent side parts successively urge the chain links apart when the chain leaves a curve, so that finally the chain links are easily caused to assume their normal position with re¬ spect to each other without being subjected to major forces.

This is additionally promoted by the rounded natur of the transition between the side edge and carrier face of a lateral projection according to the invention.

Finally, according to the invention, the chain links may be integrally moulded from a suitable plastics material in a particularly advantageous embodiment.

The invention will be explained more fully below by the description of an embodiment, which just serves as an ex¬ ample, with reference to the drawing, in which

fig. 1 shows a conveyor with a conveyor chain composed of a plurality of chain links according to the invention,

fig. 2 is a section along the line II-II in fig. 1,

fig. 3 is a perspective view of a chain link according to the invention,

fig. 4 is a top view of the same,

fig. 5 is an end view of the same,

fig. 6 is a side view of the same, fig. 7 shows part of the conveyor shown in fig. 1 which runs from a straight section into a curve,

fig. 8 is a fragmentary enlarged view of a straight run of the conveyor chain shown in fig. 7,

fig. 9 is a section along the line IX-IX in fig. 8, and

fig. 10 shows the fragment of a conveyor chain of fig. 8, but during traversal of a curve.

Fig. 1 shows a chain conveyor 1 with an endless conveyor chain 2 running over two sets of chain wheels 3a and 3b, the first of which being shown in solid line and the se- cond in broken line. The chain wheels 3a and 3b are mounted on their respective shafts 4a and 4b, respec¬ tively, and have such a tooth width and mutual spacing that they can mesh with the chain 2 and drive it by means of a suitable drive assembly (not shown). As shown best in fig. 2, the upper part 5 of the conveyor chain 2 runs on a slide base 7, which may be provided in any suitable manner, e.g. as shown with longitudinal slide rails 8 which may expediently be made of a plastics material with a low coefficient of friction. The conveyor chain 2 has guide shoes 9 along the sides which grip guide rails 10 and thereby forcibly guide the chain in its horizontal plane, so that the chain does not lift at one side when it e.g. traverses a curve. The lower part 6 of the conveyor chain 2 runs solely suspended in these guide shoes 9 in the shown example. The total arrangement is mounted on side members 11, which are in turn carried by suitable legs or suspensions (not shown).

The conveyor chain 2 is composed of a plurality of chain links 12 of the V-shaped type shown in figs. 3-6, which in this embodiment is integrally moulded from a suitable plastics material. All the chain links may be identical and consist of the shown number of V's, but, if desired, they may also be formed with a greater or smaller number of Vs. Each link 12 has a first row of eye parts 13, which are equidistantly spaced in the transverse direction of the link or the conveyor chain and are provided with a plurality of aligned openings 14 for one of the shafts by which the chain is assembled. A second row of eye parts 15 is likewise arranged in the transverse direction at a parallel-displaced distance from the first row of eye parts 13 corresponding to the chain pitch, in a manner such that centrally between each of two eye parts in the first row 13 is positioned one of the eye parts of the second row 15 which is connected with the two mentioned eye parts in the first row 13 by means of two connecting members 17, which have the same height as the eye parts 13 and 15 in the shown embodiment. The gap between the eye parts in each row is greater than the width of the respec¬ tive eye parts, and this entails that the two connecting members 17 associated with an eye part will mutually form a V. Also the second row of eye parts 15 is provided with aligned openings 16, which serve to receive a chain shaft, but continues in this case in slots 18 which are provided with the same height as the shaft openings 16 longitudi- nally through each connecting member 17. As shown, the chain links 12 have moreover cross members 19 which are arranged in the vicinity of each eye member and serve to suitably stiffen the link. As shown best in fig. 6, the slots 18 extend to the cross members 19 at the first row of eye parts 13, but the slots may also have a greater or smaller extent from the shaft openings 16 in response to their mutual horitzontal rotation which the chain links are desirably to have in the assembled chain, as will be explained more fully below. Fig. 7 shows part of a conveyor chain 2 which is provided with guide rails 10 at each side. The chain consists of a plurality of the above-mentioned chain links 12 which are assembled in rows by means of chain shafts 20 passed through the shaft openings of the eye part. The chain runs from a straight extent into a curve which it can follow because the V-shaped chain links move further and further into one another the closer the links are at the inner circle of the curve. During this movement the shafts slide simultaneously in the slot so that the entire pull in the chain will exclusively be applied on the eye parts which are positioned at the outer circle. In other words, the chain pull is thereby transferred in the curve from link to link from the first eye part on one chain link disposed outermost on a shaft to the second eye part on the next chain link disposed outermost via the common shaft, which is hereby subjected to a horizontal torque which, as shown in fig. 7, swings the shafts out of position. This effect is enhanced additionally in that the distance between the two mentioned outermost eye parts 13 and 15 is simultane¬ ously increased to some degree during the mutual horizon¬ tal swinging motion of the chain links, where the eye parts and slots on the same shaft are displaced mutually axially.

When the chain again leaves the curve, the shafts have now been swung out of position, and the links displaced mutu¬ ally axially, and in conveyor chains consisting of conven¬ tional V-shaped chain links, this state is not automati- cally restored to the intended state where the shafts are perpendicular to the feed direction, and the chain links are mutually centrally positioned, since these conventio¬ nal chain links have no means for such alignment, and the chain will therefore run with inclined shafts and dis- placed links on the following straight section, which may cause serious problems in making the teeth of the chain wheels successively mesh correctly with the chain links running into the chain wheels.

When conventional V-shaped chain links are used for making a conveyor chain to obtain very great lateral flexibility of such a chain, there will also, owing to the V-shape of the links, be a relatively large gap between the two eye parts associated with two successive chain links on a com¬ mon shaft, and in particular when these links are dis- placed axially with respect to each other. The shafts will hereby be subjected to combined bending and shear loads, which may cause so great stresses in the shafts that these will be deformed or even break. This state of load is par¬ ticularly a serious drawback when the shafts are made of a material, such as plastics, which has no great mechanical strength, but which would otherwise be a preferred mate¬ rial for many applications.

The drawbacks thus associated with the conventional V- shaped chain links are remedied by the chain link 12 of the invention, which, as shown in figs. 3-6, has lateral projections 21, 22 and 23 protruding laterally from each eye part around the shaft openings of these. The eye parts are within a region which is defined by the planes formed by the flush upper and lower sides of the slots; for maxi¬ mum strength the eye parts have a thickness which is just so much smaller than the heigth of the slot that they can enter into these slots without difficulty when the chain links swing and are displaced with respect to each other as the conveyor chain traverses a curve. As shown, each eye part 13 in the first row has a pair of outer lateral projections 21 and a pair of inner lateral projections 22, apart from the two outermost half eye parts which only have an inner lateral projection 22 each. On the other hand, each eye part 15 in the second row just has a pair of outer lateral projections 23 since the slots 18 extend precisely from the shaft openings 16 of these eye parts 15.

Figs. 8, 9 and 10 show more fully how these lateral projections operate. In figs. 8 and 9, the chain is stretched, and it appears that the inner lateral pro¬ jections 22 and outer lateral projections 23 on successive chain links on the chain keep these links in their mutual central position. As shown best in fig. 9, each lateral projection face directed toward the shaft forms a flush elongation of the part of the internal cylinder face of the adjoining shaft opening disposed in the thickness ex¬ tend of the lateral projection. This increases the total surface on the bearing faces through which the chain pull is transferred, whereby the specific surface pressure is reduced and the wear on chain links as well as shafts is reduced. The tensions occurring in the shafts under the action of a specific chain pull will simultaneously be considerably smaller than is the case under the same con- ditions when conventional chain links are used, since the outer lateral projection 21 axially extends almost to or past the opposed inner lateral projection 22 on the following chain link, thereby almost or completely avoid¬ ing the situation that the shaft is caused to bend, as was previously the case.

Fig. 10 now shows how the chain operates when traversing a curve, and, as will be seen, the chain has maintained the great horizontal flexibility known from chains with con- ventional V-shaped chain links, since the projections slide into the slots during the mutual swinging motion of the links and thus do not interfere with this motion.

When the chain leaves the curve again to traverse a straight section, adjacent lateral projections on subse¬ quent chain links will initially first contact one another during straightening of the chain, and then, sliding on each other, they successively force the chain links to assume the mutual central position shown in fig. 8 in which the shafts are simultaneously forcibly positioned at right angles to the feed direction. The mutual rotation of the lateral projections and their sliding on one another are promoted by the fact that the inner pairs of lateral projections 22 on the first row of eye parts 13 have side edges 24 diverging toward the axis of the shaft openings 14. To additionally facilitate the mutual sliding of adja¬ cent lateral projections during straightening of the chain, the transition between the side edges and carrier face of a lateral projection may be rounded, as shown by way of example by the rounding 27 on the inner lateral projection 22 of the first row of eye parts 13 (fig. 4).

Claims

P a t e n t C l a i s

1. A chain link for a laterally flexible conveyor chain, comprising a first row of eye parts which are preferably equidistantly spaced in transverse direction and have aligned openings to receive a chain shaft; a second row of eye parts which are preferably positioned centrally be¬ tween the first row of eye parts at a parallel-displaced distance from said first row of eye parts corresponding to the chain pitch and have aligned openings to receive a se¬ cond chain shaft; as well as two connecting members which are associated with each eye part and preferably have the same height as the eye parts and serve to connect, in V- shaped, the respective eye part with the two most adjacent eye parts in the second row of eye parts; the width of each eye part being smaller than the mutual spacing be¬ tween eye parts in the same row; longitudinal slots being provided transversely through the connecting members, said slots being mutually flush in transverse direction with a height substantially corresponding to the diameter of the openings of the eye parts and terminating in one row of said openings, c h a r a c t e r i z e d in that lateral projections are provided on each side of at least some of the eye parts in each row, said lateral projections ex¬ tending within a region which is defined by the planes formed by the aligned upper and lower sides, respectively, of the slots, and that each of said lateral projections has such an extent in the transverse direction that it is disposed at least in the vicinity of the opposed lateral projection on the adjacent eye part positioned on the same side of the common shaft when the respective chain link is in mounted position in a substantially stretched and straight conveyor chain.

2. A chain link according to claim 1, c h a r a c t e r ¬ i z e d in the lateral projections have a thickness which is just as great as or slightly smaller than the height of the slots.

3. A chain link according to claim 1 or 2, c h a r a c ¬ t e r i z e d in that each lateral projection is formed with a shaft carrier face, which forms a flush elongation of the part of the internal cylinder face of the adjoining shaft opening disposed in the thickness extent of the la¬ teral projection.

4. A chain link according to claim 1, 2 or 3, c h a ¬ r a c t e r i z e d in that each lateral projection has a side edge which extends from the carrier face of the late¬ ral projection and forms an angle with it, and that the side edges on at least the innermost lateral projection of the pair of lateral projections associated with an eye part diverges in a direction toward the axis of the shaft openings.

5. A chain link according to one or more of claims 1-4, c h a r a c t e r i z e d in that the transition between the side edge and carrier face of a lateral projection is rounded.

6. A chain link according to one or more of claims 1-5, c h a r a c t e r i z e d in that it is integrally moulded from a suitable plastics material.