GB2233260A

GB2233260A - Manufacturing chain

Info

Publication number: GB2233260A
Application number: GB9011957A
Authority: GB
Inventors: Theodor Kuhnigk; Wolfgang Koester; Gerhard Niemoeller
Original assignee: BECKER PRUENTE GmbH
Current assignee: BECKER PRUENTE GmbH
Priority date: 1989-06-07
Filing date: 1990-05-29
Publication date: 1991-01-09
Anticipated expiration: 2010-05-29
Also published as: GB9011957D0; GB2233260B

Abstract

In the manufacture of a chain 1 having vertical and horizontal links 2 and 3 which are the same and which each have two straight shanks 4 and 5 joined together by two bends 6 and 7, all the links 2 and 3 are bent from the same starting material and each link is formed by welding together two ends of the bent material. A steel profile is used as the starting product which is shaped by pressing, forging or rolling from round steel to have a profile consisting of lengths having flattened cross-sections for forming the shanks 4 and 5, lengths having circular cross-sections for forming the bends 6 and 7, and areas 8 having transitional cross-sections adjoining the lengths for forming the bends. <IMAGE>

Description

:22 "Round Link Chain Manufacture" The invention relates to a method of

manufacturing a round link chain having vertical and horizontal links which are the same and which each have two straight shanks joined together by two bends, all the links being bent from the same starting material and each link being formed by welding together two ends of the bent material.

Round link chains in the sense used in this specification consist of chain links which each have two rounded parts connected together by two straight shanks arranged parallel to one another. In such round link chains the planes occupied by successive links are rotated through a quadrant relative to one another so that vertical and horizontal links can be differentiated which alternate with one another. The manufacture of the chain links is carried out using a starting material which is the same for all links, from which portions are cut to a length determined by the circumference of the links and are bent into the described chain link form until the ends are lined up in one of the shanks. From these chain links, strands of chain are formed by bending the shank ends of every other link laterally in different directions so that a subsequent link can be hung on. Subsequently the shank ends are lined up by bending them backwards, and the chain strand thus manufactured can be welded in a machine. In this step the aligned ends in each link are welded to each other. In the method according to the invention this preferably takes place by means of welding so that high- strength chains are produced by this method.

Such round link chains are used in underground workings due to their great strength for the transmission of kinetic energy to mining equipment, for example coal planes or in chain belts of conveyors. In these chain drives the chains run over chain wheels which are toothed at their circumference and preferably form- locked with the horizontal chain links. In many cases the height required by the vertical chain links is a hindrance because it determines amongst other things the height of conveyor chutes which is determined by the free cross-section in which the conveyor chutes must be placed. This height however cannot be reduced by a reduction in the crosssection of the starting material from which the chain links are manufactured as described above. Rather these cross-sections are already determined by the chain halves to be taken up and define the pitch of the chain for the individual case concerned.

In the state of the art flattening the shank of the vertical links so that their height is reduced has already been proposed. This is effected on the bent vertical member by introducing into each of these chain links two pins, against which the shanks are pressed and thereby shaped in such a way that flat surfaces are produced. This method however has the disadvantage of an additional operational step during the course of manufacture described. As chains of the type described are mass produced, additional operational steps have considerable effect on the economics.

Furthermore a round link chain is known (DE-OS 37 04 176) whose vertical links have flattened shanks whilst the horizontal links overall have equal circular cross-sections and thus do not have flattened shanks. The vertical link is drop-forged complete and thus does not consist of the starting material from which both chain links are manufactured according to the described method.

The subsequent forged round chain link is bent into shape. The forging for its part represents an additional operational step which makes the chain manufacture unacceptably more expensive. Thus attempts are made to compensate for this by means of a special fashioning of the forged chain link.

Due to this different formation of vertical link and horizontal link the fitting of the chain is predetermined in one position. Thus fitting with the chain turned through 90 degrees is not possible and this is also disadvantageous.

In fact the fashioning of the forged horizontal links is so carried out that these produce a greater pitch than the vertical links. The added pitch of a vertical link and a horizontal link thus corresponds to the added pitch of two standardised chain links of equal size, but of a lower order of magnitude and weaker dimensioning. Such a chain can of course be driven by chain drums whose partial circular diameter for example is arranged for a 38 chain, although the chain pitch corresponds to a 42 chain.

This however has the disadvantage that the chain pockets for the horizontal links must be enlarged on the chain drums.

A further disadvantage is due to the special form of the vertical links in which the chain bends in the area of the apex have the greatest cross-section which diminishes towards the shanks. There is then of course a wearing pad in the area of the bends whereby the life is incre ased in this area. The relatively small crosssection in the transitional area between the bend and the shank however increases the danger of breakage in this area. Moreover differing stress ratibs occur due to the differing cross-sections in the chain link with disadvantageous reduction in strength which outweighs the wearing advantage at the bend.

An object of the invention therefore is to carry out the manufacturing method described at the beginning, according to which vertical and horizontal links are produced, in such a way that more suitable chains are produced.

According to the present invention there is provided a method of manufacturing a round link chain having vertical and horizontal links which are the same and which each have two straight shanks joined together by two bends, all the links being bent from the same starting material and each link being formed by welding together two ends of the bent material, wherein a steel profile is used as the starting product which is shaped by pressing, forging or rolling from round steel to have a profile consisting of lengths having flattened cross-sections for forming the shanks, lengths having circular cross-sections for forming the bends, and areas having transitional cross-sections adjoining the lengths for forming the bends.

In this manufacturing method according to the invention chains are produced with equal chain links because these are manufactured from the same starting material. The chain links are flattened, that is they have round cross-sections in the bend area as with round links, but are flattened in the shank area, that is reduced in height in a vertical link and in width in a horizontal link. Thus they can be used in either chain position on unmodified chain drums. The basis of the manufacturing method remains the same and is thus economical. Only the starting point is changed in that before bending of the chain steel the required crosssections of the chain links are already formed. From this starting product the lengths are obtained from which the chain links are bent. They are selected in such a way that in the area of the bend the chain link has a round cross-section. The pitches are also taken account of. In spite of the new fashioning the prior welding step remains substantially unaltered. As provision is already made in the starting product for transitions from the bend areas which are circular in cross-section into the flattened shank areas, the prerequisite is created for favourable distribution of stress upon absorption of the chain forces.

Advantageously the shaping of the starting 5 product is carried out in such a way that the crosssectional area is maintained over the whole length of the Therebv the chain link strenath re ains bar. substantially the same over the whole length of the chain link which makes a homogeneous strain pattern possible.

A further advantage follows with the assembly of the chain manufactured according to the invention. Due to the identical formation of the vertical and horizontal links, it does not depend on a defined fitting position. Thus the horizontal link can fulfill the task of the vertical link and vice versa. This is also an advantage with a chain breakage as, when joining the chain ends together independently of the broken chain link, the chain joint to be inserted is always of the same construction. Moreover the chain can be further used when the outer rounded portion is worn in that it can be turned through 90 degrees and re-inserted.

A chain manufactured in accordance with the invention can be used without changing existing conveyor chutes as it is designed according to the standard as 42 chain with 145 mm pitch, as 38 chain with 137 m pitch etc.

According to an advantageous embodiment of the invention the circular cross-section of the chain link bend is constant over a sector of 120 degrees. Thereby freedom of movement is obtained in all directions and moreover a good fit in the chain wheel pockets as already mentioned above. Due to the good freedom of movement the chain can also be used in operations with roller curves.

In order that the invention may be more fully understood, a chain manufactured in accordance with the invention will now be described, by way of example, with reference to the accompanying drawings, in which:

Figure 1 shows the chain in plan view and in diagrammatic section; Figure 2 shows the chain turned through 90 degrees by comparison with Figure 1; Figure 3 shows a section A-A taken along the line in Figure 2; Figure 4 is a side view of a forged bar used as starting product, in manufacture of the chain; Figure 5 is a plan view of the bar of Figure 4, and; Figure 6 shows sections taken along the lines B By C-Ci D-D and E-E in Figure 2.

In Figures 1 and 2 the profile link chain is shown in diagrammatic form and is generally indicated by reference numeral 1. It consists of vertical links 2 and horizontal links 3. As the horizontal links 3 and the vertical links 2 are formed identically, only one of these links is described in the following. Each link 2 or 3 consists of two shanks 4 and 5 extending parallel to one 9 another and joined together by two bends 6 and 7. The bends have a constant circular cross-section over a sector of 120 degrees as shown in Figure 1 and Figure 6 (section E-E). The circular cross-section of the bends 6 and 7 merges continuously without sharp edges into the crosssectional profile of the shanks 4 and 5. In the present examplary embodiment according to Figure 3, the shank cross-sectional profile is approximately rectangular with rounded off edges, the edges facing outwards having a smaller radius than the edges facing inwards. This is shown particularly in Figure 3. The profiling of the shank areas means that these are flattened in contrast to normal round links. This flattening however does not occur at the expense of the cross-sectional area of the shank because during profiling the size of the original cross-sectional area is not altered in the same way as it is not altered in the area of the bend. As is particularly shown in Figures 3 and 6, the width of the shank -profile is identical to the diameter of the bend cross-sectional area. It can however be greater than the width in the bend area.

The chain links 2 and 3 are made from a chain steel bar cut to length, as shown in Figures 4 and 5. These in side view in an area of somewhat trapezoidal shape form the transitional areas from the bends to the shanks. The areas 4 and 5 form the flattened shank areas whilst the areas 6 and 7 which are larger in diameter form the bends. The latter areas still have the original diameter of the shaped bar. After bending the areas 4 at the free ends of the bar contact each other and are welded together. The welded seam is indicated in Figures 1 and 2 by reference numeral 9. 5 Figure 6 shows in detail how the transition takes place continuously from the cross- sectional form of Figure 3 (section A-A) to the circular cross-section (section E-E) without sharp edges occurring. Due to the identical formation of horizontal and vertical links, automated manufacture is possible. At the same time optimum symmetry of the chain is produced which firstly favours a homogeneous force distribution within the chain and secondly simplifies the fitting of the chain.

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Claims

1. A method of manufacturing a round link chain having vertical and horizontal links whichare the same and which each have two straight shanks joined together by two bends, all the links being bent from the same starting material and each link being formed by welding together two ends of the bent material, wherein a steel profile is used as the starting product which is shaped by pressing, forging or rolling from round steel to have a profile consisting of lengths having flattened cross-sections for forming the shanks, lengths having circular cross-sections for forming the bends, and areas having transitional cross-sections adjoining the lengths for forming the bends.

2. A method according to claim 1, wherein in the starting product used the transitions between the flattened cross-sections for forming the shanks and the circular cross-sections for forming the bends merge continuously without sharp edges from one cross-section to the other via intermediate profiles.

3. A method according to claim 1 or 2, wherein the cross-sectional area of the shanksis the same as the cross-sectional area of the bends.

4. A method according to any one of claims 1 to 3, 25 wherein in the starting material the lengths which are circular in cross-section extend over a bend angle of 120 degrees after bending and the adjacent transitions merge into the shanks.

5. A method according to any one of claims 1 to 4, wherein the flattened lengthsof the starting material have an approximately quadrangular cross-section.

6. A method according to any one of claims 1 to 4, 5 wherein the flattened lengths of the starting material have an approximately rectangular cross-section.

7. A method according to any one of claims 1 to 6, wherein the flattened cross-sections have rounded corners for forming rounded edges on the shanks.

8. A method according to any one of claims 1 to 4, wherein the flattened lengthsof the starting material have an approximately oval cross-section whose minor axis lies in the plane of the chain link.

9. A method according to any one of claims 1 to 4, 15 wherein the flattened areas of the starting material have an approximately semicircular cross-section whose base forms the outer limiting surface of the chain link shank.

10. A method of manufacturing a round link chain substantially as hereinbefore described with reference to the accompanying drawings.

Published 1991 at The Patent Office. State House. 66171 High Holborn. London WC1R 4TP. Further copies may be obtained from The Patent Office. Sales Branch. St Mayy Cray. Orpington, Kent BR5 3RD. Printed by Multiplex techniques ltd. St Man. Cray. Kent. Con. 1187 -----wil. 0, Mary Lay. MrplngLuli, ncia,----- ---.Y ---1. 1101