Conveyor chain

Abstract: Conveyor chain comprising a plurality of identical chain links (1) which are interconnected by means of transversely extending hinge pins through eye parts in the front edge and the rear edge of each chain link, and each chain link is designed with a top plate (2) arranged to support the items to be transported, said top plate being provided with fingers (5) and intermediate recesses (6) for engagement with the fingers and recesses of adjacent chain links. Each chain link comprises at least one cover face (12) at one of the edges (4) of the chain link, said face being situated at a level below the top plate (2) and such that the face may slide under the fingers of an adjacent chain link when the conveyor chain turns. The result is an introduction of "bottoms" in the openings occurring by running in curves with chain links with fingers.

Description: State of the art The invention relates to a conveyor chain comprising a plurality of identical chain links as stated in the introduction of claim 1. The applicant's allowed U.S. Patent Application No. 045,188 (Danish Patent Application No. 0523/92; DE-A-4 312 864) describes chain links with fingers and recesses in the front and rear edges enabling them to be interconnected to form a chain which is swingable and adapted for running in curves and the like, and moreover adapted in such a manner that only small openings will occur in the top surface of the conveyor. In total, the result is a more plane surface and a smaller non-supporting surface area than by the prior art conveyor chains, which has many advantages. However, in such chain links there still occurs small openings in the support surface of the chain, in particular as regards the chain links situated in a curve, in that openings will occur between the chain links in the outer edge of the curve, said openings being partly or completely closed again when the chain links in question run into a straight-line area again. There is accordingly a risk that protruding parts of the objects resting on the conveyor may get jammed or be damaged when the openings close, cf. above, and a possibility that persons acting incautiously may get a finger, pieces of clothing or the like jammed in the openings, which may perhaps cause personal injury. The applicant's prior U.S. Patent No. 4,754,872 describes chain links with ribs on the top plate, where the ribs increase in length from the centre towards the edges, but in such chain link conveyors there are still comparatively large openings. The support surface in this type of chain link is moreover comprised by upturned rib edges, ie. not a plane top surface. The applicant's prior U.S. Patent No. 5,027,944 describes a chain link with arrow-shaped wings and a plane top plate having offset areas which may slide under the wings of the adjacent chain link in order to reduce the size of the openings occurring by running in curves. On the other hand, areas are obtained in the support surface of the top plate which are not in the same plane so that curves will either have to be made with a large radius or conveyors of this kind may only be used for transporting relatively large objects due to the design of the support surface. Prior art document DE-A-4 312 864 discloses a conveyor band having individual links which are able to turn about two axes in relation to an adjacent link. The links are provided with cover faces in the corners of the links, such that these are overlapped by extensions of a top plate of an adjacent link thereby, to some extent, covering the opening at the corners, which would appear, had the cover face not been provided. The extensions of the cover face is substantially of the same thickness as the top face and both are only supported by the top plate. This document forms the preamble of claim 1. Advantages of the invention By designing the conveyor chain according to the invention as disclosed in the characterising part of claim 1 all the advantages of the prior art conveyor chains with fingers, for example of the kind described in U.S. Patent Application No. 045,188, are maintained while openings are substantially avoided from occurring in the top surface, whereby the risk of objects becoming caught in the conveyor band is substantially decreased. By designing the conveyor chain according to the invention as disclosed in claim 1, the cover face will form a bottom in the areas between the fingers, ie. in the recesses. Should parts of objects to be conveyed fall down on the cover face, when the band is turning, these will be lifted up again when the individual chain links run from a curve area to a straight-line area. Since the cover face is always supported by the track and the cover face is substantially thinner than the fingers, the probability of items getting caught between the adjacent links will be strongly reduced. It will only be possible to introduce objects, between the fingers of the chain links the few millimetres of space which the finger is offset relative to the top surface of the track. The conveyor chain according to the invention may be designed as, disclosed in the characterising parts of claim 2, 3, 4 or 5. It will be obvious to a person skilled in the art that the invention may be applied in connection with many different designs of the fingers and recesses. A reduction in thickness of the fingers by one edge of each chain link will not reduce the supporting capacity of the chain links since these fingers may rest on the cover face of the adjacent chain link to the extent this may be required. Chain links for the conveyor according to the invention as defined in claim 4 may be formed in plastic or in steel, without extra manufacturing costs so that the chain link conveyor according to the invention, apart from the technical advantages and the advantages in relation to safety, also has economic advantages compared to the prior art chain links. The drawing Three embodiments of the invention will now be explained further with reference to the drawing, wherein: fig. 1 is a top view of a chain link according to a first embodiment, fig. 2 is a bottom view of the same chain link, fig. 3 is a side view along III-III in fig. 1 of the same chain link, fig. 4 is a plane section of the chain link along IV-IV in fig. 1, fig. 5 is a section of interconnected chain links in a curve according to fig. 1, fig. 6 is a section VI-VI of the chain in fig. 5 running in a straight line, fig. 7 is a top view of a chain link according to the invention according to a second embodiment, fig. 8 is a side view along VIII-VIII in fig. 7, fig. 9 is a plane section along IX-IX in fig. 7, fig. 10 is a section of interconnected chain links in a curve according to fig. 7, fig. 11 is a section XI-XI of the chain in fig. 10 running in a straight line, fig. 12 is a section of interconnected chain links in a curve according to a third embodiment, and fig. 13 is two of the chain links in fig. 12 running in a straight line. Explanation of embodiments In the embodiments shown in the drawing the chain links 1, 1' are moulded in plastic, but as will also appear from the drawing, the chain link 1 shown in figs. 1-6 is of quite the same kind as the one described in the applicant's own allowed U.S. Patent Application No. 045,188 relating to chain links of plastic as well as chain links of steel. It will therefore be obvious to a person skilled in the art and appear from the following explanation that the present invention may be carried out in the form of plastic chain links as well as steel chain links for forming endless conveyor chains. The two embodiments have therefore been included to illustrate that the invention may be carried out in connection with any type of conveyor chains with a top plate with fingers for achieving the desired technical effect. Each chain link 1, 1' comprises a front edge 3, 3' and a rear edge 4, 4' when the running direction is as shown by the arrow T showing the preferred running direction, but there is of course nothing to prevent the chain links according to the invention from running in the opposite direction. Each chain link 1, 1' has eye parts 7, 7' by the front edge 3, 3' adapted to secure a hinge pin 10, 10' with a centre axis 11, 11', and arranged in a manner known per se to enter into engagement with a transverse opening 9, 9' in the eye part 8, 8' of the adjacent chain link in the rear edge 4, 4' of the adjacent chain link. The transverse opening 9, 9' in the eye part 8, 8' may for example be designed with an increasing clearance from the longitudinal centre line of the chain link as shown in fig. 7, but may also be designed in other manners, for example in the form of a known, built-in cardan joint. Chain links of the shown kind moreover comprise a central lower part 17, which supports a top plate 2, 2' for supporting the objects to be transported, and underlying finns 16, see fig. 3, or hinge eyes 7', see figs. 7-9, arranged in such a manner that the conveyor chain may be retained in engagement with the track controlling the chain, if required. The top plate 2, 2' of the chain links has fingers 5, 5' and recesses 6, 6', so that adjacent chain links 1, 1' may engage each other as shown in figs. 5 and 10. The type of chain link 1 in figs. 1-6 moreover has a central finger 15 for engagement with a central recess 19 with a notch 20 in the adjacent chain link for reducing openings in the top plate, and moreover as explained in the applicant's own above-mentioned U.S. Patent Application. However, it clearly appears from figs. 5 and 10 that despite fingers and recesses the conveyor chain opens somewhat at the outer edge of a curve with the risk that small objects or parts of objects or a finger or loose pieces of personal clothing etc. may inadvertently be introduced into the openings created, and get jammed if not removed before the conveyor reaches a straight-line area, where the openings are closed. To avoid this, the chain links according to the invention are provided with a cover face 12, preferably at either side by one of the edges of the chain link; in the example shown by the rear edge 4, 4' of the chain link. The cover faces 12, 12' are substantially plane faces, which are moulded or die-stamped integrally with the chain link itself. If the chain links are produced by sintering, the cover faces are made while forming and sintering the remaining part of each chain link. Preferably, the cover faces 12, 12' completely cover the openings in the chain links resulting from the recesses 6, ie. the area between the fingers 5, but may also, as shown in fig. 10, cover a larger area. The result is the introduction of a "bottom" in the openings occurring by running in curves with chain links of that kind. The cover 12, 12' is offset a few millimetres, for example by an offset 13, 13' of a few millimetres, and the cover 12, 12' accordingly provides a substantially plane area of material as mentioned above. This will prevent objects, fingers etc. to be introduced into the openings occurring between the fingers and the recesses by running in curves, and should this nevertheless happen, then the objects or the fingers may only be introduced a few millimetres whereupon they will hit against the cover face 12, 12'. When the chain links run from an area with a curve to a straight-line area, the openings between the fingers and the recesses will close, and any objects introduced into the openings will be lifted up onto the top surface of the chain link again without being damaged. It will also appear from the drawing that the fingers 5, 5' of the chain links have rounded edges, thereby completely preventing objects, fingers etc. from getting jammed. The cover faces 12, 12' shown in the drawing terminate in a straight edge 14, 14', which is either designed as shown in fig. 1 with two cover faces 12, one at either side of the chain link, or, as shown in fig. 7, with one common transverse cover face 12' extending across the entire chain link, but there is of course nothing to prevent the edge 14, 14' from having any other shape. However, it is of major importance to the possibility of the chain links running freely in curves that there is room for the cover face/faces 12, 12'. Therefore, the shown designs of the edge 14, 14' are advantageous in many structures. In order to make room for the cover face 12, 12', the fingers 5, 5' by the opposite edge of the chain link have been made a little thinner, for example by a small offset 18, 18' from the lower side, see for example figs. 4, 6, 8 and 11. It moreover appears from fig. 6 and fig. 11 of the drawing that the fingers 5, 5' may rest on the cover face 12, 12' of the adjacent chain link at least during straight-line running and, dependent on the design and the size of the cover face or faces, also when the chain links are in a curve. Figs. 12-13 show an embodiment of the invention corresponding to the type shown in figs. 1-6, but wherein fingers 5 and recesses 6 almost join so that there is practically only one finger 5 and one recess 6 at either side of each chain link, and so that under the top plate 2 there is room for the cover face 12 of the adjacent chain link. Moreover, the chain links operate as explained above, and in figs. 12 and 13 the same reference numerals as used in figs. 1-6 for equal or similar parts have been used. It furthermore clearly appears from fig. 13 that the conveyor chain has an unbroken top plate by straight-line running and that by running in curves, as shown in fig. 12, the chain gets only quite small and slit-like openings in that the vast majority of the openings, which arise, are covered by the cover face 12.

Claims: Conveyor chain comprising a plurality of identical chain links (1, 1') which are interconnected by means of transversly extending hinge pins (10, 10') inserted through eye parts at the front edge (3, 3') and the rear edge (4, 4'), respectively, of adjacent chain links enabling each pair of hinged links to be mutually swingable, whereby one of the edges (3, 3') of each chain link comprises two eye parts (7, 7') for securing a hinge pin, whereas the other edge (4, 4') comprises an eye part (8, 8') with a transversly extending opening (9, 9') for receiving the hinge pin of the adjacent chain link, and wherein each chain link comprises a top plate (2, 2') arranged to support the items to be transported, said top plate being provided with fingers (5, 5') and intermediate recesses (6, 6') extending from the front edge and rear edge of the chain links for engagement with the fingers and recesses of the adjacent chain links, characterised in that each chain link furthermore comprises a cover face (12, 12' ) at one or more of the edges (4, 4') of the chain link, said cover face being situated at a level below the top plate (2, 2'), such that the cover face may slide under the fingers of an adjacent chain link when the conveyor chain turns, thereby substantially covering the openings in the chain links resulting from the recesses between the fingers, the fingers (5, 5') and the cover face (12, 12') being substantially plane, the thickness of the fingers (5, 5') being greater than the thickness of the cover face (12, 12'), the cover face (12, 12') being adapted to be directly supported by a track on which the links (1, 1') glide, and the cover face (12, 12') being arranged to partly overlap the fingers of an adjacent chain link when the chain links are positioned on a straight line. Conveyor chain according to claim 1, characterised in that the sum of the thickness of the cover face (12, 12') and the thickness of the fingers (5, 5') substantially equals or is slightly smaller than the thickness of the top plate. Conveyor chain according to any one of claims 1 or 2 wherein each chain link is formed as an integrally moulded plastic unit, characterised in that the cover faces (12, 12') are integrally moulded with the rest of the chain link. Conveyor chain according to any one of claims 1 or 2 wherein each chain link is formed in steel by deformation or working of an object and as an integral unit, characterised in that the cover faces (12, 12') have been produced by die-stamping, sintering or working of the object. Conveyor chain according to any preceding claim, characterised in that the cover faces (12, 12') are provided at the rear edge of the chain link (1, 1') in the preferred direction of travel.

Inventors: DAMKJAER POUL ERIK, DAMKJAER, POUL ERIK
Applicants: BAELTIX MASKINFABRIKKEN AS, MASKINFABRIKKEN BAELTIX A/S
Application year: 1995
Main classification: B65G17
IPC codes: B65G17