GB2420609A

GB2420609A - Chain link assembly

Info

Publication number: GB2420609A
Application number: GB0426205A
Authority: GB
Inventors: Michael Bradney
Original assignee: Renold PLC
Current assignee: Renold PLC
Priority date: 2004-11-30
Filing date: 2004-11-30
Publication date: 2006-05-31
Also published as: GB0426205D0

Abstract

A chain having interlaced chain links 11 and transverse chain pins 16 is assembled by supplying a group of aligned chain links 21 to an assembly area 17 and then using an actuator 22 to displace pre-selected links in a direction substantially parallel to the longitudinal axis of the chain. The pre-selected links are displaced by one chain pitch and one or more chain pins 16 are then inserted into the pin holes of the newly aligned pin holes. The assembly method provides for a simple and efficient way of assembling a chain. The pin holes of the chain links 11 may be aligned using an alignment tool 26 prior to the insertion of the chain pins 16.

Description

CHAIN LINK ASSEMBLY

The present invention relates to a method for assembling a chain comprising a plurality of interleaved chain link plates and apparatus for employing said method.

The invention is particularly, but not exclusively applicable to a leaf chain (also referred to in the industry as a balance or lifting chain) of the kind used on forklift truck masts to raise and lower the fork carriage.

A leaf chain comprises interlaced parallel link plates that are joined by transverse pins. Inner link plates are a slip fit with the pins such that they articulate whereas outer link plates are a friction or interference fit such that they do not articulate. The inner link plates can be arranged into interlaced groups, each group comprising two or more plates that are coterminous along the longitudinal axis of the chain.

Traditionally chains of this kind were assembled manually by interlacing the inner link plates on the pins and then applying the outer link plates. In some cases in recent times at least part of this process has been automated with link plates being fed by conveyors and chutes and mechanical devices being used to position the plates on the pins. This approach is labour intensive as it requires dextrous manipulation of the plates and accurate positional control to ensure that they are loaded on to the pins.

It is an object of the present invention to obviate or mitigate the aforesaid and other disadvantages by providing for a method and apparatus that improves the chain assembly operation.

According to a first aspect of the present invention there is provided a method for assembling a chain, the chain comprising interlaced chain links and defining a longitudinal axis, adjacent links being joined by transverse chain pins, each link comprising first and second pin holes, the method comprising the steps of: supplying a group of aligned chain links to an assembly area; using an actuator to displace pre- selected links in a direction substantially parallel to the longitudinal axis of the chain by one chain pitch so that the second pin holes of the displaced links are aligned with the first pin holes of the non-displaced links; and inserting a chain pin in a direction transverse to the longitudinal axis of the chain into the newly aligned pin holes.

The invention provides for an efficient and cost-effective manner of rapid chain assembly.

The chain links are preferably advanced by a distance substantially equal to one link length and this is preferably effected after said displacement of the pre- selected links.

The displaced and non-displaced links are ideally held in alignment as a transverse chain pin is inserted.

The links are preferably held in alignment by inserting an alignment pin from one side of the links into the newly aligned pin holes and then retracting the alignment pin simultaneously with the transverse chain pin being inserted into the same holes from the other side of the links.

The chain pins may be inserted individually or, more ideally, in pairs simultaneously at adjacent locations along the chain. More than two chain pins may be inserted at once.

Preferably a pair of chain pins is inserted simultaneously at adjacent locations along the chain, and two alignment pins are simultaneously used to hold the plates in alignment.

The alignment pins may be disposed on a support at a spacing equal to the space between adjacent pin holes. There may be provided recesses for supporting the pins, the recesses being defined on a support surface adjacent the chain links prior to insertion.

Preferably an insertion tool comprising insertion pins is used to slide the chain pins along the recesses and into the pin holes.

Outer links are ideally pressed on to the ends of the chain pins after the chain pins have been inserted.

Ideally the links are supported between guide walls as they are displaced and advanced.

The group of links are preferably supplied from a store of links by a movable platform that moves the group to a position between the guide walls and adjacent to the actuator.

The method preferably includes the step of selecting the platform to have the capacity to carry the number of chain links required to occupy the width of the chain.

Moreover, the links are preferably supported once they are displaced and before the pins are inserted by using a retaining member that occupies a clearance between ends of the displaced and non-displaced links.

The actuator ideally contacts the ends of the selected chain links during the displacement step. It may have at least one projection for displacing the link plates and the actuator is preferably selected to have a projection that has a width corresponding to the width of the chain link or links to be displaced. The actuator is selected to be of a length equal to the chain pitch.

According to a second aspect of the present invention there is provided apparatus for assembling a chain that comprises interlaced chain links and defines a longitudinal axis, adjacent links being joined by transverse chain pins, each link comprising first and second pin holes, the apparatus comprising supply means for supplying a group of aligned link plates, an actuator movable between a retracted position where it is adjacent to said supply means and an extended position in which it displaces pre-selected links in said supplied group of link plates in a direction substantially parallel to the longitudinal axis of the chain by one chain pitch so that the second pin holes of the displaced links are aligned with the first pin holes of the non- displaced links; a pin support for receipt of a chain pin for insertion into the pin holes and a pin insertion tool movable in a direction transverse to the longitudinal axis of the chain between a retracted position where it is adjacent to the pin support and an extended position where the chain pin is inserted into the newly aligned pin holes.

The actuator may be movable to a second extended position which is a distance of substantially one chain link beyond the first extended position. The actuator preferably comprises a main body and a projection having a length substantially equal to chain pitch. The projection ideally has a width equal to or less than the width of the link plates to be displaced.

Specific embodiments of the present invention will now be described, by way of example only, with reference to the accompanying drawings in which: Figure 1 is a plan view of chain assembly apparatus according to the present invention and shown assembling a leaf chain; Figure 2 is a side view showing part of the apparatus of figure 1; Figures 3 to 7 are plan views of the apparatus shown at different stages during the assembly process; Figure 8 is a plan view showing an alternative embodiment of a pusher member of the apparatus for assembling a chain of an alternative configuration; and Figure 9 is a side view of the pusher member and chain of figure 8.

The drawings illustrate the assembly of a strand of leaf chain using the exemplary apparatus. The chain strand 10 is assembled from a plurality of identical, substantially planar link plates 11 each having two spaced pin holes 12, 13. The link plates 11 are arranged by the apparatus into interleaved groups comprising two outer groups 14 of three link plates flanking a middle group 15 of two link plates that are offset along the axis of the chain by a distance equating to the chain pitch P. Once the links are arranged into this configuration transverse cylindrical chain pins 16 are successively inserted into aligned pin holes 12, 13 to join adjacent groups of link plates 11 together. As the assembly progresses operates the chain advances from right to lefi in the figures.

The assembly apparatus comprises an assembly table 17 supporting a pusher member 18 that serves to move successive batches of plates 11 into the correct alignment between parallel guide walls 19 and to feed them to a pin insertion station 20. Link plates 11 are fed from a continuously replenished store 21 of aligned pre- fabricated link plates (shown in dotted line) disposed below the level of the table 17 and that extends in a direction substantially perpendicular to the longitudinal axis of the chain.

The pusher member 18 has a substantially rectangular main body 22 and a thin projection 23 of a length that is equivalent to the pitch P of the chain links 11 and a thickness equal to that of two chain link plates 11. It is configured to slide in a rectilinear direction along the table between the guide walls 19 and under the control of a linear actuator such as a hydraulic or pneumatic ram (not shown). The pusher member 18 is movable between a retracted position shown in figures 1 to 3 and 5 to 7 and an advanced position as shown in figure 4. Upstream from the pusher member 18 the store of link plates 21 is fed in a direction perpendicular to the longitudinal axis of the chain so as to load a batch of plates on to a vertically moveable platform 24 disposed below the assembly table 17 and between the guide walls 19. The platform 24 indexes from a position below the table where it is loaded with plates 11 to a position level with the table 17 so that the plates are in the path of the pusher member 18 between the guide walls 19.

Downstream from the platform 24 the guide walls 19 are flanked by a pin holder 25 and a plate alignment tool 26 that together form the pin insertion station 20.

The pin holder 25 comprises a raised surface with a pair of spaced elongate grooves 27 that correspond substantially to the shape of the pins 16. The grooves 27 support the pins 16 in the appropriate lateral and vertical position for insertion into the pin holes 12, 13 of the link plates 11. It will be understood that the guide walls 19 have openings through which the pins 16 pass so that they can be inserted into the pin holes 12, 13. On the other side the alignment tool 26 comprises pair of alignment pins 28 that extend from a supporting plate 29. The tool 26 is movable from a retracted position shown in figures 1, 3 and 4 to an advanced position shown in figure 5 by a linear actuator such as a pneumatic or hydraulic ram (not shown). Each alignment pin 28 is substantially similar in size to the chain pins 16 but has a tapered end 30 to facilitate its insertion into the pin holes 12, 13 of the link plates 11.

Immediately adjacent to the pin holder 25 there is a pin insertion tool 31 (figures 3 to 7) that is configured similarly to the plate alignment tool 26 except that the ends of the pins 32 are not tapered. The pins 32 of the insertion tool 31 have their longitudinal axes L aligned with the pins 16 supported by the pin holder 25.

In all of the figures the chain strand 10 is shown partially assembled with the plates 11 downstream from the insertion station 20 having been joined by the pins 16.

The link plates 11 awaiting assembly at the pin insertion station 20 are held in the aligned position by a retaining clip 33 of spring steel or the like that is supported by an arm 34 extending from one of the guide walls 19. The clip 33 is disposed such that it occupies a space 35 between the outer groups of plates 14 where the next central group of plates 15 is to be received and thus serves to maintain the lateral spacing between the two outer groups of plates 14.

In operation, the platform 24 receives a batch of eight link plates 11 from the store 21 and is moved upwardly to present the batch to the pusher member 18 as shown in figures 1, 2 and 3. The platform 24 is moved by any convenient means such as a motor operated lead screw or a hydraulic or pneumatic ram actuator (not shown).

The pusher member 18 is then advanced from the position shown in figures 1 to 3 to that illustrated in figure 4. During this advancement the projection 23 first contacts the middle two plates 15 and displaces them relative to the other plates of the batch by a distance equal to its length i.e. the pitch length of the chain. The group 15 comprising the middle two plates are thus offset relative to the two groups 14 comprising the outer flanks of three link plates. As the pusher member 1 8 continues to advance, all of the plates 11 are moved together, in their offset configuration, by a distance just exceeding one plate length to the position shown in figure 4. During this latter movement the middle two plates pass under the retaining member 33 which simply deflects upwardly to permit their movement as illustrated by the dotted line 33a is figure 2.

The pusher member 18 then retracts to the position shown in figure 5 and simultaneously, at the insertion station 20, the plate alignment tool 26 is advanced so that the alignment pins 28 are received in the aligned pins holes 12, 13 of the unassembled link plates 11. The alignment tool 26 serves to hold the link plates 11 in the correct alignment as the real pins 16 are inserted. At the stage the retaining clip 33 holds the latest outer groups of link plates 14 in the correct lateral spacing as shown in figure 1.

The pin insertion tool 31 then advances to contact the ends of the pins 16 supported in the grooves 27 of the holder 25 and pushes them along the grooves towards the unassembled chain links 11. As the pins 16 advance their leading ends abut the ends of the alignment pins 28 such that they are supported at each end between the pin insertion tool 31 and the plate alignment tool 26. The tools 26, 31 and the pins 16 then move in unison: the plate alignment tool 26 retracting from the link plates 11 such that the alignment pins 28 are brought clear of the pin holes 12, 13 and the pin insertion tool advancing at the same rate to push the pins 16 into the pin holes 12, 13 to replace the retracting alignment pins 28. The final position of the pin insertion stage is shown in figure 6.

Finally the pin insertion and plate alignment tools 31, 26 retract to the positions shown in figure 7 and the cycle starts again.

The assembled strand of chain 10 is then passed to the next stage where the outer link plates (not shown) are assembled in a friction fit on the exposed ends of the pins 16 an a conventional manner.

The present invention provides for an efficient and accurate method of chain assembly without significant manual intervention.

An alternative embodiment of the pusher member and chain configuration is shown in figures 8 and 9. This chain 50 is interlaced such that it comprises a total of five groups of two plates 11 arranged into two intermediate groups 51 that are offset by one chain pitch from the other groups which comprise two outer pairs 52 and a central pair 53 of plates. In order to assemble this chain the pusher member 54 has two parallel projections 55, 56 for simultaneously moving the two intermediate groups 51 of link plates into their offset positions.

It will be appreciated that numerous modifications to the above described design may be made without departing from the scope of the invention as defined in the appended claims. For example, the link plates may be of any suitable configuration and they may be interlaced in any suitable configuration. Moreover, in some embodiments the pin insertion tool may be designed to insert only one pin at a time in which case the plate alignment tool only has one alignment pin. Alternatively more than two pins may be inserted simultaneously in which case the apparatus is adapted to supply two or more rows of aligned link plates at once before the actuator is operated to displace the selected links.

Claims

A method for assembling a chain, the chain comprising interlaced chain links and defining a longitudinal axis, adjacent links being joined by transverse chain pins, each link comprising first and second pin holes, the method comprising the steps of: supplying a group of aligned chain links to an assembly area; using an actuator to displace pre-selected links in a direction substantially parallel to the longitudinal axis of the chain by one chain pitch so that the second pin holes of the displaced links are aligned with the first pin holes of the non-displaced links; and inserting a chain pin in a direction transverse to the longitudinal axis of the chain into the newly aligned pin holes.
2. A method according to claim 1, further comprising the step of advancing the chain links by a distance substantially equal to one link length.
3. A method according to claim 2, wherein the chain links are advanced by said one link length after said displacement of the pre-selected links.
4. A method according to any preceding claim, wherein the displaced and non-displaced links are held in alignment as a transverse chain pin is inserted.
5. A method according to claim 4, wherein links are held in alignment by inserting an alignment pin from one side of the links into the newly aligned pin holes and then retracting the alignment pin simultaneously with the transverse chain pin being inserted into the same holes from the other side of the links.
6. A method according to claim 1, wherein a pair of transverse chain pins is inserted simultaneously at adjacent locations along the chain.
7. A method according to claim 5, wherein a pair of chain pins are inserted simultaneously at adjacent locations along the chain, and two alignment pins are simultaneously used to hold the plates in alignment.
8. A method according to claim 6 or 7, wherein the alignment pins are disposed on a support at a spacing equal to the space between adjacent pin holes.
9. A method according to claim 8, further comprising the step of supporting the chain pins in recesses defined on a support surface adjacent the chain links prior to insertion.
10. A method according to claim 9, further comprising the step of using an insertion tool comprising insertion pins to slide the chain pins along the recesses and into the pin holes.
11. A method according to any preceding claim, further comprising the step of pressing outer links on to the ends of the chain pins after the chain pins have been inserted.
12. A method according to any preceding claim, further comprising the step of supporting the links between guide walls as they are displaced and advanced.
13. A method according any preceding claim, wherein the group of links are supplied from a store of links by a movable platform that moves the group to a position between the guide walls and adjacent to the actuator.
14. A method according to claim 13, further comprising the step of selecting the platform to have the capacity to carry the number of chain links required to occupy the width of the chain
15. A method according any preceding claim, further comprising the step of supporting the links once they are displaced and before the pins are inserted by using a retaining member that occupies a clearance between ends of the displaced and non-displaced links.
16. A method according to any preceding claim, wherein the actuator contacts the ends of the selected chain links during the displacement step.
17. A method according to any preceding claim, wherein the actuator has at least one projection for displacing the link plates and the actuator is selected to have a projection that has a width corresponding to the width of the chain link or links to be displaced.
18. A method according to any preceding claim, wherein the actuator is selected to be of a length equal to the chain pitch.
19. Apparatus for assembling a chain that comprises interlaced chain links and defines a longitudinal axis, adjacent links being joined by transverse chain pins, each link comprising first and second pin holes, the apparatus comprising supply means for supplying a group of aligned link plates, an actuator movable between a retracted position where it is adjacent to said supply means and an extended position in which it displaces pre-selected links in said supplied group of link plates in a direction substantially parallel to the longitudinal axis of the chain by one chain pitch so that the second pin holes of the displaced links are aligned with the first pin holes of the non-displaced links; a pin support for receipt of a chain pin for insertion into the pin holes and a pin insertion tool movable in a direction transverse to the longitudinal axis of the chain between a retracted position where it is adjacent to the pin support and an extended position where the chain pin is inserted into the newly aligned pin holes.
20. Apparatus according to claim 19, wherein the actuator is movable to a second extended position which is a distance of substantially one chain link beyond the first extended position.
21. Apparatus according to claim 19 or 20, wherein the actuator comprises a main body and a projection having a length substantially equal to chain pitch.
22. Apparatus according to claim 21, wherein the projection has a width equal to or less than the width of the link plates to be displaced.
23. Apparatus according to any one of claims 19 to 22, wherein there provided a pin alignment tool disposed opposite the pin insertion tool, the pin alignment tool comprising an alignment pin for insertion into the aligned pin holes on a side opposite the pin insertion tool, the alignment tool being movable from a retracted position where it is clear of chain and an extended position wherein the alignment pin is received in the aligned pin holes of the chain links.
24. Apparatus according to claim 23, wherein the pin alignment tool and the pin insertion tool are movable simultaneously.
25. Apparatus according to claim 23 or 24, wherein the pin alignment tool comprises a pair of transverse alignment pins connected to a supporting member.
26. Apparatus according to any one of claims 23 to 25, wherein the, or each, alignment pin has a tapered end.
27. Apparatus according to any one of claims 19 to 26, wherein the pin support comprises a recess for support of the chain pin prior to insertion.
28. Apparatus according to claim 27, wherein there are a pair of recesses for supporting two spaced chain pins prior to insertion.
29. Apparatus according to any one of claims 19 to 28, wherein there is provided guide walls between which the actuator and the supply means are disposed, the pin insertion tool being disposed to one side of one of the walls.
30. Apparatus according to any one of claims 29, wherein the supply means is a movable platform that moves the group of links to a position between the guide walls and adjacent to the actuator.
31. Apparatus according to any one of claims 29 or 30, further comprising a retaining member disposed between said guide walls and biased to occupy a clearance between ends of the displaced and non-displaced links.
32. Apparatus substantially as hereinbefore described with reference to the accompanying drawings.
33. A method for assembling a chain substantially as hereinbefore described with reference to the accompanying drawings.