CONVEYOR CHAIN AND ARRANGEMENT AND METHOD FOR CONNECTING THE LINKS THEREOF

Abstract: The invention relates to an arrangement for an articulated joining of a first (1a) and a second (1b) links constituting a chain, and a method for joining the links (1a, 1b) into a conveyor chain. The first chain link (1a) carries a connecting dowel pin (11a) extending through head part (2b) of the second chain link (1b) parallel to the first axis of rotation, whereby one of the connecting dowel pin (11a) and head part (2b) exhibits protrusion (12) with a first guiding surface. The second dowel pin (11a) and head part (2b) exhibit seat (10) which is in gliding contact with protrusion (12) and has a second guiding surface, complementary to the first gliding surface. The gliding surfaces are curved around the first as well as the second axes of rotation and thus form a link defining the first and the second axes of rotation.

Description: CONVEYOR CHAIN AND ARRANGEMENT AND METHOD FOR CONNECTING THE LINKS THEREOF Field of the Invention The present invention generally relates to a conveyor chain as well as an arrangement and a method for connecting chain links included in the conveyor chain. More specifically, the present invention relates to a conveyor chain, whose links are pivotable in relation to each other about a first and a second pivot axis extended transversely of the conveyor chain, which pivot axes are mutually perpendicular, the first link supporting a coupling pin, which extends through a head portion of the second link along the first pivot axis, one of the coupling pin and the head portion having a projection with a first joint surface and the other of the coupling pin and the head portion having a seat slidingly abutting against the projection with a second joint surface complementary to the first joint surface, which joint surfaces are curved about the second pivot axis and thus form a joint which defines this second pivot axis. Background of the Invention A conveyor chain of the above-mentioned type is disclosed ,in US-2, 091, 836. According to an embodiment of this prior-art conveyor chain, two links included in the conveyor chain are connected by means of a coupling pin. The coupling pin is pivotally mounted in a pair of legs of one of the links, and the coupling pin extends through a head portion of the other link. The coupling pin has a part-cylindrical projection, which abuts against a part- cylindrical seat of the head portion, whereby the projec- tion and the seat form a joint which permits a lateral pivoting of the links in relation to each other. A vertical pivoting of the links in relation to each other is permitted by pivoting about the pivotally mounted coupling pin. The desired pivoting between two links of the conveyor chain is thus achieved on the one hand by the joint formed by the projection and the seat and, on the other, by the rotation of the coupling pin. No additional components are required to achieve said pivoting, which, of course, results in a relatively low manufacturing cost of the conveyor chain. There are, however, some disadvantages of this prior-art conveyor chain. First, the links are placed in frictional contact with each other during operation, in particular as the conveyor chain turns. This friction causes noise as well as wear on the links, which in turn generates dust. To reduce this problem it is known to add a lubricant to the material of which the links are made, in most cases a plastic material, which addition reduces the tensile strength of the links. For certain types of conveyor chains, it is known, in order to solve the problem of friction between the links, to arrange a metallic sliding surface therebetween to reduce the friction. This solution reduces the noise and wear, but an additional element has to be mounted on each link of the chain, re- suiting in a higher manufacturing cost. Second, the mounting of the conveyor chain is relatively complicated. When connecting two links, the links must in fact be angled relative to each other to permit the introduction of the coupling pin. This makes the mounting time-consuming and thus expensive. Summary of the Invention In consideration of that stated above, one object of the present invention is to provide an improved conveyor chain as regards its construction and assembly. Thus the invention provides an arrangement for articulated connecting of a first and a second link included in a conveyor chain, which links are pivotable in rela- tion to each other about a first and a second pivot axis extended transversely of the conveyor chain, which pivot axes are mutually perpendicular, the first link supporting a coupling pin, which extends through a head portion of the second link along the first pivot axis, one of the coupling pin and the head portion having a projection with a first joint surface and the other of the coupling pin and the head portion having a seat slidingly abutting against the projection with a second joint surface complementary to the first joint surface, which joint surfaces are curved about the second pivot axis and thus form a joint which defines said second pivot axis, which arrangement is characterised in that the joint surfaces are curved also about the first pivot axis, whereby the joint formed by the thus double-curved joint surfaces also defines the first pivot axis, and that the coupling pin is axially fixed in relation to the first link. The joint formed by the joint surfaces causes the coupling pin to be positioned in relation to the head portion of the second link. Moreover, the axial fixing of the coupling pin also results in the joint being positioned in relation to the first link. Thus the first and the second link are positioned in relation to each other. This makes it possible to eliminate, or at any rate substantially reduce, the generation of friction and the problems related to this. According to a preferred embodiment of the invention, the generation of friction is eliminated by a play between the links, which prevents wear and which can be maintained by said axial fixing of the coupling pin when the links pivot relative to each other about the second pivot axis. Thus the noise, the wear and the dust generated by the friction of the links against each other are eliminated or reduced. It is to be noted that this is achieved without any additional elements being mounted on the link. According to another preferred embodiment of the invention, the joint is so constructed that it can be formed, when mounting the arrangement, by placing the coupling pin in the head portion of the second link and subsequently displacing the coupling pin in relation to the head portion away from the second link until the joint surface of the projection and the joint surface of the seat are in contact with each other, the arrangement being such that the coupling pin is axially and non- rotatably fixed in the first link as a consequence of said displacement. By reason of this, such a simple connecting of the links is achieved that the connecting operation can be automated, which, of course, permits a cost-effective production of conveyor chains. Preferably, said displacement is achieved by stretching the conveyor chain. Preferably, the projection is arranged on the coupling pin and the seat is arranged in the head portion. Further, it is advantageous if the projection is integral with the coupling pin, the seat being integral with the head portion. Preferably, the projection is made of a material having greater hardness than the seat. According to a preferred embodiment, the projection is made of a metallic material, whereas the seat is made of a polymer material . According to yet another embodiment of the present invention, the coupling pin extends through long holes, which are made in the head portion. These long holes on the one hand permit pivoting of the links in relation to each other about the first of said pivot axes and, on the other, permit displacement of the links in relation to each other in the longitudinal direction of the chain. As a result, it is possible to bring the seat and the pro- jection into contact with each other by stretching the chain to provide said articulate function. In addition, it is possible to compress the chain in its longitudinal direction, i.e. it is contractible . This can be an advantage when the chain is to be introduced into a return path, the contractility making it possible to reduce the "slack" of the chain which otherwise can form at the entry of the return path. Additional preferred features of the inventive arrangement are stated in the claims dependent on claim 1. Moreover, according to the invention a conveyor chain is provided which is characterised in that its links are connected by means of arrangements according to the invention. It is thus possible to provide a conveyor chain which is cheap to manufacture since only one element - a coupling pin - is required for the connecting of the links of the conveyor chain, the connecting also being easy to carry out. Moreover, it is possible to eliminate the friction and the problems related to this since the joint formed by the coupling pin and the head portion in combination with a play for instance between the links can prevent any contact between certain parts of the links. Finally, according to the invention a method for connecting a first and a second link of a conveyor chain is provided, which are pivotable in relation to each other about a first and a second pivot axis extended transversely of the conveyor chain, which pivot axes are mutually perpendicular, which method comprises the step of placing a coupling pin of the first link in a head portion of the second link, which coupling pin extends along the first pivot axis, one of the coupling pin and the head portion having a projection with a first joint surface and the other of the coupling pin and the head portion having a seat slidingly abutting against the projection with a second joint surface complementary to the first joint surface, which joint surfaces are curved about the second pivot axis and thus form a joint which defines said second pivot axis, which method is characterised by the steps of arranging the head portion of the second link between a pair of legs of the first link, subsequently introducing the coupling pin into recesses in the pair of legs and into recesses in the head portion, and finally displacing the links away from each other to axially and non-rotatably fix the coupling pin in the first link and to bring said joint surfaces together to form said joint, the thus double-curved joint surfaces also being curved about the first pivot axis, whereby the joint formed by the joint surfaces also defines the first pivot axis. The inventive method permits the mounting of a conveyor chain of the type stated above and having the above-mentioned advantages. Other preferred embodiments of the invention are stated in the dependent claims. In the following, the invention will be described by way of example with reference to the accompanying drawings. Summary of the Drawings Fig. 1 is a plan view of a link constructed according to the present invention. Fig. 2 is a side view of the link in Fig. 1. Fig. 3 is a plan view of a coupling pin, which is constructed according to the present invention. Fig. 4 is an end view of the coupling pin in Fig. 3. Fig. 5 is a plan view of two links according to Fig. 1, which are connected with a coupling pin according to Fig. 3. Fig. 6 is a side view of the connected links in Fig. 5. Fig. 7 is a side view of the connected links in Fig. 5 in a pivoted condition. Fig. 8 is a cross-sectional view along the line I-I in Fig. 6. Fig. 9 is a cross-sectional view along the line II-II in Fig. 6. Description of Embodiments With reference to Figs 1 and 2, an embodiment is shown of a link 1 according to the present invention. The link 1 has a head portion 2 and a pair of legs 3, which extends in the direction away from the head portion 2 and whose free ends 4 are spaced from each other. In the free end 4 of each leg 3, a "keyhole" 5 is made, which key- holes 5 extend in the longitudinal direction of the link 1. Each keyhole 5 is formed of a big recess 6 and a small recess 7. Each of the small recesses 7 is partially surrounded by a locking means in the form of an open cylindrical part 8. Further, two long holes 9 are made on each side of the head portion 2, which long holes 9 extend in the longitudinal direction of the link 1. Moreover, the head portion 2 is hollow and has an internal, part- spherical seat made in its front end, which is apparent from the dashed line at 10 and from Fig. 9. In this description, part-spherical means a shape constituting a part of a sphere. Common to all the figures of the link 1 is that a supporting surface arranged thereon is omitted to clarify the description of the invention. In the practical use of the conveyor chain according to the present invention, each link is, however, normally provided with such a supporting surface. The link 1 is preferably made of a polymer material. Fig. 3 shows a coupling pin 11. The coupling pin 11 is substantially cylindrical, but has a central, part- spherical projection 12. The centre of the part-spherical projection 12 coincides with the longitudinal axis 13 of the coupling pin 11. As shown in Fig. 4, the projection 12 has a radius R and a width B. In this embodiment, the radius R is greater than the radius of the pin 11, which makes the projection 12 protrude from the pin 11 and form a maximum dimension L of the coupling pin 11a trans- versely of its longitudinal direction. The width B of the projection 12 is equal to or smaller than the diameter of the pin 11 and forms a minimum dimension of the coupling pin 11a, which minimum dimension equals the diameter of the coupling pin 11a. The diameter of the coupling pin 11a substantially equals the height H of the long holes 9 in Fig. 2. Moreover, a groove 14 is made at each end portion of the coupling pin 11. To attach the coupling pin 11 to the link 1, the pin 11 is introduced into one of the big recesses 6 and then out of the other big recess 6. The two grooves 14 are so arranged that they will be placed at a keyhole 5 each. In a subsequent parallel displacement of the coupling pin 11 away from the head portion 2, the grooves 14 permit the coupling pin 11 to be introduced into the small recesses 7 at the same time as it snaps into the open cylindrical parts 8, which lock the coupling pin 11, so that it cannot be displaced in the direction of the head portion 2. The grooves 14 prevent the coupling pin 11 from axial displacement and rotation about its longitudinal axis. Figs 5-7 show a first link la and a second link lb, which are identical with the one shown in Fig. 1 and connected by means of a coupling pin 11a according to Fig. 3. The coupling pin 11a extends right through the head portion 2b via the long holes 9. The projection 12 and the seat 10 are in contact with one another. To connect the links la, lb, the head portion 2b is placed between the pair of legs 3a. Then the coupling pin 11a is introduced into one of the big recesses 6 and then into one of the long holes 9. The coupling pin 11a must be turned such that it can be passed through the long hole, i.e. so that the projection 12 extends along the long hole. The coupling pin 11a is subsequently passed through the other long hole 9 and finally out of the other big recess 6. After this, the coupling pin 11a is attached to the pair of legs 3a according to the description above. Now the links la and lb are connected. The long holes 9 permit relative displacement of the links la and lb to a degree corresponding to the extent of the long holes 9. By applying tensile stress to the chain, i.e. by stretching the chain, the links la and lb are moved away from each other. As a result, the projection 12 and the seat 10 are brought into contact with each other. In this contact, the head portion 2b and the coupling pin 11a are positioned in relation to each other since the joint formed by the projection 12 and the seat 10 functions as a guiding means. Since the seat 10 and the projection 12 are centred on the head portion 2b and the coupling pin 11a, respectively, the latter are also centred in rela- tion to each other. Further, the coupling pin is axially fixed in the first link la, whereby the links la and lb are positioned in relation to each when the conveyor chain is stretched. As long as the chain is stretched, the function of the joint will be maintained, and thus said positioning and centring will also be maintained. The joint permits the links la and lb to pivot in relation to each other about two pivot axes X and Y which are mutually perpendicular and extend transversely of the conveyor chain. Fig. 7 shows the links la and lb pivoted in relation to each other about the pivot axis X. It is to be noted that the positioning of the coupling pin 11a in relation to the head portion 2b is maintained when turning the chain. In the embodiment shown, the part-spherical seat 10 forms a relatively large joint surface for the projection 12, which joint surface is shown in Fig. 9 for instance. As mentioned above, a large joint surface results in less wear on the joint, and therefore, according to the invention, it is resistant to wear and thus has a relatively long service life. Preferably, the coupling pin 11a, with its integral projection 12, is made of a metallic material, whereas the link lb, with its head portion 2b and the seat 10 formed therein, is made of a polymer material. As a result, the friction in the joint is reduced, which implies less wear and a longer service life. It is in particular to be noted that this rela- tively large joint surface is achieved by means of the coupling pin 11a and the head portion 2b only. When manufacturing the links la and lb, such seats 10 can be made integral with the head portions 2a and 2b, and when manufacturing the coupling pins 11a and lib, such pro- jections 12 can be made integral therewith. Thus no additional components are needed to form the joint, which means that the manufacturing cost of the conveyor chain can be maintained at a relatively low level at the same time as its resistance to wear will be high. In Figs 8 and 9, it is illustrated how a coupling pin 11a is attached to a pair of legs 3a. The coupling pin 11a is snapped into the open cylindrical parts 8 so that it cannot be displaced in the longitudinal direction of the link la. Moreover, the grooves 14 engage in the pair of legs 3a. This results on the one hand in the pin 11a not being displaceable in the axial direction and, on the other, the pin 11a not being pivotal about its longitudinal axis. As the coupling pin 11a is axially fixed, the head portion 2b, which is positioned in relation to the coupling pin 11a when the chain is stretched, is also positioned in relation to the first link la. The fact that the pin cannot rotate about its longitudinal axis implies that the projection 12 cannot turn away from the seat 10. As is evident from e.g. Fig. 9, there is a play S between the head portion 2b and the pair of legs 3a. This play S, together with the above-mentioned positioning of the head portion 2b, permits the elimination of friction. The reason for this is that the links la and lb are positioned in relation to each other when the chain is stretched, the design of the joint securing that this positioning can also be maintained when the links la and lb pivot in relation to each other. Thus the head portion 2b does not abut against the pair of legs 3a, which means that friction cannot be generated. As already mentioned, friction can cause much noise and wear on the links la and lb. Wear in turn generates dust, which, as well as the noise, is a big work environment problem. It is understood that the invention is not limited to the embodiment described above. It is, of course, possible to construct the links so that the pivot axes X and Y change places, i.e. so that the coupling pin extends along the pivot axis Y. However, according to the preferred embodiment, the coupling pin extends along the pivot axis X according to the accompanying figures. Moreover, it is understood that it is possible to form the seat in the pin and the projection in the head portion. The appended claims are intended to cover all changes and modifications within the scope of the invention.

Claims: CLAIMS 1. An arrangement for articulated connecting of a first (la) and a second (lb) link included in a conveyor chain, which links (la, lb) are pivotable in relation to each other about a first (X) and a second (Y) pivot axis extended transversely of the conveyor chain, which pivot axes (X, Y) are mutually perpendicular, the first link (la) supporting a coupling pin (11a) , which extends through a head portion (2b) of the second link (lb) along the first pivot axis (X), one of the coupling pin (11a) and the head portion (2b) having a projection (12) with a first joint surface and the other of the coupling pin (11a) and the head portion (2b) having a seat (10) slidingly abutting against the projection (12) with a second joint surface complementary to the first joint surface, which joint surfaces are curved about the second pivot axis (Y) and thus form a joint which defines said second pivot axis (Y) , c h a r a c t e r i s e d in that the joint surfaces are curved also about the first pivot axis (X), whereby the joint formed by the thus double-curved joint surfaces also defines the first pivot axis (X) , and that the coupling pin (11a) is axially fixed in relation to the first link (la) . 2. An arrangement according to claim 1, c h a r a c t e r i s e d in that the coupling pin (11a) is also non-rotatably fixed in relation to the first link (la). 3. An arrangement according to claim 1 or 2, c h a r a c t e r i s e d by a play (S) between the links (la, lb), which prevents wear and which can be maintained by said axial fixing of the coupling pin (11a) when the links (la, lb) pivot relative to each other about the second pivot axis (Y) . 4. An arrangement according to any one of the preceding claims, c h a r a c t e r i s e d in that the joint is so constructed that it can be formed, when mounting the arrangement, by placing the coupling pin (11a) in the head portion (2b) of the second link (lb) and subsequently displacing the coupling pin (11a) in relation to the head portion (2b) away from the second link (lb) until the joint surface of the projection (12) and the joint surface of the seat (10) are in contact with each other, the arrangement being such that the coupling pin (11a) is axially and non-rotatably fixed in the first link (la) as a consequence of said displace- ment . 5. An arrangement according to claim 4, c h a r a c t e r i s e d in that said displacement is achieved by stretching the conveyor chain. β. An arrangement according to claim 4 or 5, c h a r a c t e r i s e d in that the coupling pin (11a) , to provide said axial and non-rotatable fixing of the coupling pin (11a) in the first link (la), has grooves (14) extended transversely of its longitudinal direction, which grooves are arranged to engage in recesses (5) in connection with said displacement, which recesses are made in the first link (la) . 7. An arrangement according to any one of claims 4- 6, c h a r a c t e r i s e d in that the arrangement is such that the coupling pin (11a) is fixed in the first link (la) in the longitudinal direction of the conveyor chain as a consequence of said displacement. 8. An arrangement according to any one of the preceding claims, c h a r a c t e r i s e d in that the joint is so constructed that the links (la, lb) are displaceable towards each other when the conveyor chain is not stretched, whereby the joint obtains its joint function only if the conveyor chain is stretched. 9. An arrangement according to any one of the preceding claims, wherein the head portion (2b) is provided with two long holes (9) through which the coupling pin (11a) is extended to permit said pivoting movement about the second pivot axis (Y) . 10. An arrangement according to claim 9, c h a r a c t e r i s e d in that the long holes (9) permit displacement of the links (la, lb) in relation to each other. 11. An arrangement according to claim 9 or 11, c h a r a c t e r i s e d in that the long holes (9) have a height (H) , which is substantially equal to the thickness of the coupling pin (11a) . 12. An arrangement according to claim 11, c h a r - a c t e r i s e d in that the projection (12) is arranged on the coupling pin (11a), and that a maximum dimension (L) of the coupling pin (11a) with the projection (12) transversely of the first pivot axis (X) exceeds the height (H) of the long holes (9), the coupling pin (11a) with the projection (12) being insertable through the long holes (9) if the coupling pin (11a) is rotated so that said maximum dimension (L) coincides with the longitudinal direction of the long holes (9). 13. An arrangement according to any one of the preceding claims, c h a r a c t e r i s e d in that the joint has a pivot centre, which coincides with the longitudinal axis of the coupling pin (11a). 14. An arrangement according to any one of the preceding claims, c h a r a c t e r i s e d in that the projection (12) is arranged on the coupling pin (11a), and that the seat (10) is arranged in the head portion (2b) . 15. An arrangement according to claim 14, c h a r a c t e r i s e d in that the projection (12) has a centre, which coincides with the longitudinal axis of the coupling pin (11a) . 16. An arrangement according to claim 14 or 15, c h a r a c t e r i s e d in that the projection (12) is integral with the coupling pin (11a) . 17. An arrangement according to any one of claims 14-16, c h a r a c t e r i s e d in that the seat (10) is integral with the head portion (2b) . 18. A conveyor chain comprising a plurality of links (1) and arrangements, each arrangement being arranged for articulated connecting of a first (X) and a second (Y) link included in the conveyor chain, the links (la, lb) being pivotable in relation to each other about a first (X) and a second (Y) pivot axis extended transversely of the conveyor chain, which pivot axes (X, Y) are mutually perpendicular, the first link (la) supporting a coupling pin (11a), which extends through a head portion (2b) of the second link (lb) along the first pivot axis (X), one of the coupling pin (11a) and the head portion (2b) having a projection (12) with a first joint surface and the other of the coupling pin (11a) and the head portion (2b) having a seat (10) slidingly abutting against the projection (12) with a second joint surface complementary to the first joint surface, which joint surfaces are curved about the second pivot axis (Y) and thus form a joint which defines said second pivot axis (Y) , c h a r a c t e r i s e d in that each arrangement is so constructed that the joint surfaces of each arrangement are curved also about the first pivot axis (X) , whereby the joint formed by the thus double-curved joint surfaces also defines the first pivot axis (X) , that the coupling pin (11a) is both axially and non- rotatably fixed in relation to the first link (la) , and that there is a play (S) between the links (la, lb), which prevents wear and which by said axial fixing of the coupling pin (11a) can be maintained when the links (la, lb) pivot relative to each other about the second pivot axis (Y) . 19. A method for connecting a first (11a) and a second (lib) link of a conveyor chain, which links (11a, lib) are pivotable in relation to each other about a first (X) and a second (Y) pivot axis extended transversely of the conveyor chain, which pivot axes (X, Y) are mutually perpendicular, which method comprises the step of placing a coupling pin (11a) of the first link (la) in a head portion (2b) of the second link (lb), which coupling pin (11a) then extends along the first pivot axis (X), one of the coupling pin (11a) and the head portion (2b) having a projection (12) with a first joint surface and the other of the coupling pin (11a) and the head portion (2b) having a seat (10) slidingly abutting against the projection (12) with a second joint surface complementary to the first joint surface, which joint surfaces are curved about the second pivot axis (Y) and thus form a joint which defines said second pivot axis (Y) , c h a r a c t e r i s e d by the steps of arranging the head portion (2) of the second link (lb) between a pair of legs (3) of the first link (la), subsequently introducing the coupling pin (11a) into recesses (5) in the pair of legs (3) and into recesses (9) in the head portion (2), and finally displacing the links (la, lb) away from each other to axially and non-rotatably fix the coupling pin (11a) in the first link (la) and to bring said joint surfaces together to form said joint, the thus double-curved joint surfaces also being curved about the first pivot axis (X), whereby the joint formed by the joint surfaces also defines the first pivot axis (X) .

Inventors: JOHANSSON LARS JOERGEN, LUNDGREN GOERAN, JOHANSSON, LARS, JOERGEN, LUNDGREN, GOERAN
Applicants: MOVING AB
Application year: 1998
Main classification: B65G17
IPC codes: B65G17