US2319979A - Conveyer - Google Patents

Description

May 25, 1943. R. R. COLLINS ETAL CONVEYER Filed April 29, 1942 ATTO RN EY Patented May 25, 1943 CONVEYER Raymond R. Collins, Southport, Conn., and John A. Gibb, Northport, N. Y., asslgnors to The Lummus Company, New York, N. Y., a corporation of Delaware Application April 29, 1942, Serial No. 440,936

(Cl. I4-252) 3 Claims.

This invention relates to improvements in link chains and more particularly to articulated conveyer chains for heavy-duty work.

The principal object of the invention is to provide an improved articulated link construction for a chain which will have substantially increased strength as compared to the ordinary link of its same cross section.

A more specific object of the invention is to provide an improved articula-ted link chain for heavy-duty, high-temperature operation, in Which the cross section of the link can be substantially reduced as compared to standard construction without lowering the factor of safety and in which the link will have a. greater useful life than the standard links otherwise available.

Another object of the invention is to provide an improved method of field fabrication of links for heavy-duty conveyer chains, in which'a link can be quickly created in the field with spare parts all of which are of uniform construction, such parts being integrated into a rigid link by commonly available field equipment.

Another object of the invention is to provide I an improved form of. conveyer link which Will have the strength of a forged link, but which can 4be integrated from individual side bars, pins, and

4l'thimble portions, each of which is a most economicalshape for its purpose.

Further objects and advantages of the invention will appear from the following description of a preferred form of embodiment thereof taken in connection with the attached drawing illustrative thereof and in which Fig.-1 is a plan view with parts in section of a part of a link chain;

Fig'. 2 is a side view with parts in section of the construction shown in Fig. 1.

The standard type of articulated chain link consists usually of a pair of side bars which may be straight or offset, some spacing device coinmonly known as the thimble for one end of the bars, and a pin for the other end of the bars, such pin passing through the thimble. Customarily, this thimble extends through the end of the bars with the result that the side of the bars is suitably bored or cut to receive the end of the thimble.

Such a construction, however, 'has a tensile strength which islimited to the minimum cross sectional area, which can be placed in tension, and this is a function of the size of the thimble which is required as well as the size of the pin. With small chains, this is not critical, but with a conveyer for heavy-duty loading, it is found necessary to have a. minimum sprocket width. which is reflected in the length of the thimble between the side bars of the link, and this will require at least a minimum diameter to obtain a sufficiently high section modulus to prevent bending.

-In accordance with a preferred form of embodiment of the invention, we have been able to increase the effective strength of the link so that the full size thimble and pin may be used and yet the effective area in tension is substantially larger than the actual available cross section of the side bar.

In the attached drawing, the link is provided with side bars I0 and Il, which are shown as offset but which might be parallel if desired.

Preferably, they are made offset so that all of the pieces in the chain are identical and replacements are more readily made. With the offset bar, it is preferable to use a thimble I 4, which projects through the Walls of the side bars I0 and II t0 more directly distribute tension loads from the sprocket-engaging thimble directly to the side bars. The adjacent link, consisting of the side bars Ilia and Ila, engages over the narrow end of the side bars I0 and II of the link, and a pin I5a projects through the thimble I4 and the ends of the side bars I0a and Ila. A pin I5 also extends through the side bars I0 and II, and the thimble Mb of the adjacent link on the other end.

In accordance with the invention, we form the parts of the link into an integrated member by welding the -thimble I 4 to the side bars around the periphery as at Il, such weld being of the penetration type and formed in the V-recess made by the chamfered edges on the thimble and the opening in the side bars. In a similar manner, the pin I5 is welded to the side bars of the adjacent link at IB,

An unexpected advantage of such a construction will appear from a consideration of the following typical case:

It is desired to apply a load of 5500 pounds to each side bar in order to operate a conveyer which consists of two chains carrying buckets for the delivery of clay at the rate of tons per hour through an elevation of feet. The weight of the chain, the impact load, and the weight of the full buckets indicate a load of 5500 pounds per side bar or a total of 22,000 pounds per conveyer. The links are 12-I on centers.

Assuming a thickness -of side bar of with a bar which is 4" wide, and assuming a 11/2" solid pin I 5, with a thimble of 21/2 diameter and with a square edse opening 2" wide.the net cross sectional area will be 4"-2"=2.0" times .375" or .75 square inch. lhe unit stress is then 5500/.'150=' i5 0 pounds/sq. in.

A welded structure will reinforce the opening, and as provided by standard engineering practice (A. P. I. and A. S. M. E. codes), it is permissible to add two and a hali.' times the thickness of the reinforcing member or the reinforced member whichever is thinnest. In this case, the reinforcing member is the wall oi' the thimble which is V2" thick and the reinforced member is the side bar which is thick. The net cross section for the net opening in the side bar is 4.0"-1.5"=2.5"x.375=.94 square inches.

In addition, it is permissible to add 2 l/2 x x 2:1.8'75 square inches in accordance with the above formula. The emeiency ofI such a weld is assumed to be 80% for an unrelieved, non-radiographed weld so that the added area=1.5 sq. in. The total area is thus 1.5 plus .94=2.44 sq. in. The unit stress is then 5500/2.44=2290 pounds/sq. in.

The conditions on the outer bar are also improved for the welding of a solid pin filling the opening does not reduce the cross section at all except by the eillciency of the Weld so that with a 5,500 pound load on a 4" bar, thick, the stress will be 3,700 pounds per square inch. In each case the unit stress is thus very much lower than the unit stress according to customary practice with the result that either greater loads can be used or a greater factor of safety provided or the bar can be reduced in cross sectional size.

There is also an important advantage in that the provision of headed bolts or external securing pins or keys is entirely eliminated with a result that the overall dimensions can be reduced from 5 to 20 per cent, thus materially reducing the expense of the conveyer covers, guides, etc.

It is contemplated that, in accordance with our invention, units of chain from 12 to 20 feet long will be completely' assembled in the shop and suillcient parts, including side bars and pins and thimbles, be supplied for completing .the chain. In such case the pins, side bars and thimbles would be suitably chamfered so that they could be immediately assembled and welded in the field. For practical purposes, it will be noted that the pin andthe thimble are provided with a small amount of overlap 20 for centering purposes in the respective ends of the side bars. This does not reduce the strength of the weld but avoids any possible accidental shifting during the welding operation.

If at any time it is desired to dismantle any part of the unit, a pin may be removed by merely inserting a suitable size drill and drilling out the welded portion from each end, after which the pin can be driven out and the chain broken. In a similar manner. the thimbles may also be removed if this is desired.

If such a chain is to be used for conveying purposes, it may be found desirable to weld a plate bracket 22 to the side bars l0 and ll, such plate having an upturned arm 2l to which one edge of the bucket, not shown, may be applied. Such a bracket also increases the strength of the link.

While we have shown and described a preferred form of embodiment of our invention, we are aware that modifications may be made thereto and we, therefore, desire a broad interpretation of our invention within the scope and spirit od the description herein and of the claims ap-l pended hereinafter.

We claim:

l. A fabricated rigid link for a sprocket chain comprising side bars, a transverse pin, and a transverse hollow thimble through which a similar pin is adapted to pass, said side bars being apertured at adjacent ends to receive the thimble and the pin, said side bars being welded to the thimble and to the pin whereby Ithe effective tensile strength of the link is materially increased, the said thimble terminating with the outer sides of the side bars and the said pin terminating with the outer sides of the side bars through which it passes.

2. A conveyer chain composed of a plurality of links having side bars, transverse pins, and transverse thimbles, said side bars being apertured to receive a pin at one end and a lthimble at the other, said thimble being hollow to receive the pins of adjacent links, the links being integrated into a rigid structure by welding the external faces of the pins and the thimbles flush with the external faces of the side bars.

3. A fabricated rigid link for a sprocket chain comprising side bars and transverse members, said side bars being apertured to receive transverse members, one of said transverse members being tubular, the walls of which are of a thickness at least equal to the wall thickness of the side bars, said tubular transverse members being welded to the said side bars adjacent the apertures therein whereby the reinforcement of the welded tubular transverse members provides an effective minimum cross-section area through the apertured portion of the side bars, which is substantially greater than the actual crosssection subjected to longitudinal stresses in the side bar.

RAYMOND R. COLLINS. JOHN A. GIBB.

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