US2385049A - Lifting tongs - Google Patents

Description

Sept. 18, 1945. R, H. BATES LIFTING' TONGS Filed June 17, 1944 Patented Sept. 18, 1945- UNITED STATES rATENT OFFICE LIFTING 'roNGs Raymond yH. Bates, Waterbury, Conn. Application June 17, 1944, seriainaaiaszs 2 Claims. (Cl. 2il4flil8) This invention relates to lifting tongs and has for an object to provide a pair of tongs having parallel jaws which are automatically clamped against the work and held in this vposition by the action of a lifting means.

Another object is to provide lifting tongs which may be used for handling coils of hot sheet metal without gripping them from the outside of the coil so as to crush them.

A further object is to provide improved means for holding the jaws of such a device in the open condition while being lowered t the Work engage ing position, and may be easily and quickly released to permit gripping of the work.

With the foregoing and other objects in view l have .devised the construction illustrated in the accompanying drawing forming a part of this specication. It is, however,l to be understood the invention is not limited to the specic details of construction and arrangement shown but may embody various changes and modications within the scope of the invention.

In the drawing:

Fig. 1 is a side elevation of the lifting tongs in position to carry a pair of coiled strips of metal, parts of the coils `being broken away to more clearly show the operation andthe tongs being shown in Adotted lines in the released position;

Fig 2 is a side elevation looking from the left of Fig. 1 with a portion of the nearest coil broken away, and

Fig. 3 is al horizontal section substantially on line 3-3 of Fig. 1, showing a plan view of the coils.

These lifting tongs were devised for lifting and carrying various articles, but were developed primarily for use in brass or rolling mills for carrying coils of sheet or strip metal and particularly for unloading coils of hot sheet metal or coiled strips from muilie pans, and are so constructed as not to require gripping of the outside of the coils which would crush them, particularly as the metal when hot is soft and is easily bent cr deformed. They comprise a pair of jaws r5 having gripping portions 6 at one end of the shank 1. Each of these jaws may be a substantially rectangular bar, and they shank adjacent the opposite end from the gripping portion 6 is provided with an elongated slot 8 extending transversely therethrough.

Located on each side of the jaws is a pair of links 9 which cross intermedaite their ends and are pivoted together at Ill. The lower ends are pivoted at II to the jaws 5 adjacent the grip 6 and they are also connected to the Shanks of the jaws 5 by the pivot pins I2 one in each of the slots 8. 'It is preferred that the pivots II and I2Ibe spaced equal distances from 'the pivot IIl between thetwo links so that as the links swing 'on the pivot ID .and the jaws move toward and from'each other they will always be maintained parallel to each other.

Connected and pivoted to the upper ends or opposite ends from the connection to the jaws are a'. pair of levers I3. These levers are each pivoted at one end to one of the links at I4 and cross ea'ch other and are pivoted together at I5. At thefopp'osite ends these two levers are each connected to a hoisting means such for example as a ring I-B by a flexible means such for example as a chain or cable I1. In lifting the tongs ,thehook from the crane or hoist (not shown) may be' inserted in the ring I6 and carries the weight of the'v tongs and any article carried thereby. It will be seen that the pull of the lifting device on the ring I.6 and chains I1 will tend to draw the upper ends of the levers `I3 together swinging them about the pivot I'5, and this will swing the lower ends of the levers toward each other which will act through the pivotal connections I to swing the upper ends of the links 9 toward each other `about their connecting pivot I Il. This willshift the pivotal connections I I and I2 to the two spaced jaws toward each other carrying with them the jaws 5 and will cause the portions ,6 to grip any article located between these ,portions i.ofthe jaws. As previously indicated the pivot pins I.2 slide in the slots 8, and because they are spaced the same distance from the pivotal connection I0 as are the pivots Il to the jaws, the jaws will always Ibe maintained in parallel relation. It will also be seen that as the pull of the lifting mechanism acts to clamp the jaws on the work the greater this pull or the heavier the article or articles being carried the greater will be the gripping action of the jaws on the article. The pivots I0, II, I2 and I4 extend between the two pairs of links 9 located on opposite sides of the jaws 5 so that the two pairs of links are operated in unison and each carries its proportional share of the load. Suitable spacing collars `I8 and I9 may be provided on the pivotal pins I4 between the links 9 and the connecting lever I3, and there may be similar spacing collars between the outer links 9a and the jaws 5 0n the pins II and I2.

Simple and effective means is provided for holding the jaws in the open position when no article is being gripped and facilitate moving of the tongs to the article gripping position. This comprises a catch`2l] pivoted to one of the levers I3 at 2| spaced from the pivotal connection I5 between the levers, in the present case above this connection I5, and provided with a hook 22 adapted to engage a lug or pin 23 on the other lever I3 spaced from the pivotal connection I5 on the opposite side thereof, in the present case below this connection. As the catch is above the pivot I5, hook 22 depends from the pivot 2| and will therefore automatically engage the pin 23 when the levers are sulciently expanded to bring this pin into alignment with the hook. 'I'he catch may have a shank 24 for hand operation of the catch.

The device, although adapted for carrying various articles, is shown as gripping two coils 25 of at or strip metal arranged side by side, such for example as two coils of heated metal to transferv them to or from a muie pan. It will be seen the jaws are adapted to be inserted within the inner side of the coils and to grip the inner walls of the coils and clamp the two adjacent sides of the coils together Yinstead of gripping the outer sides of the coils, and therefore there is no danger of crushing the coils by the gripping action of the jaws and two coils may be carried just as readily at one time as could one coil. In operation, the jaws are opened sufliciently to permit the catch 20 to engage the pin'23,`as indicated in dotted lines Fig. 1. This supports the weight of the jaws so they cannot move toward each other and maintains them in the separated position indicated by the dotted lines. The jaws in this position can be lowered by crane or other mechanism to bring the gripping portions Ei of the jaws within the coils 25. Then by merely releasing the catch 297th@ weight of the jaws and the links 9 assisted by the pull of the chains I'I on the levers I3 will cause the jaws to move toward each other and the gripping portions 6 to engage the inner sides of the coils, as indicated in full lines in Figs. 1 and 3. Then lifting on the ring I6 by the crane or other lifting device, will, by the further pull on the chains I'I and the levers I3, further tend to clamp the jaws againstA the coils 25 through action of the links 9, as above described, and itV will be seen thatthe greater the weight of the coils 25 and therefore the greater the pull on the chains I'I. the greater will be the gripping action on the 'coils so that they will be effectively gripped and held by the jaws, and this gripping action is automatic from the lifting action of the crane, After-the coils have been transferred to the desired location they may be lowered in the usual manner and after they are deposited on a support further lowering of the hook connected to the ring I6 will permit the levers I3 to move downwardly further and open up to permit the catch 20 to engage the pin 23. This movement of the levers will spread the upper ends of the links 9 and the`jaws 5, and after the hook 22 is in engagement with the pin 23 the tongs may readily be lifted from the coils 25 and again shifted to Aother articles.

Having thus set forth the nature of myinvention, what I claim is: l. Lifting tongs comprising a pair of jaws each including a shank provided with a gripping portion at one end thereof, a pair of links on each of the opposite sides of the shanks, the links of each pair being pivoted together intermediate their lengths and at one end to one of the jaws adjacent the gripping portion thereof, each shank being provided with an elongated slot adjacent its other end, a pivot pin passing through each slot and connecting the links on the opposite sides ofthe shank, a pair of levers pivoted together intermediate their lengths and each having one end located between the free ends of the corresponding links on the opposite sides of a jaw and pivoted to said links, a lifting means connected to each of the opposite ends of the levers and tending by a pull thereon to shift the levers to operate the jaws to grip an article, and releasable means for holding the levers in the expanded position with the jaws away from the article.

2. Lifting tongs comprising a pair of jaws each including a shank provided with a gripping p0rtion at one end thereof, a pair of links on each of the opposite sides ofthe Shanks, the links of each pair being pivoted together intermediate their lengths and at one end to one of the jaws adjacent the gripping portion thereof, each shank being provided with an elongated slot adjacent its other endy a pivot pin passing through each slot and connecting the links on the opposite sides of the shank, a pair of levers pivoted together intermediate their lengths and each having one end located between the free ends of the corresponding links on the opposite sides of a jaw and pivoted to said links, and a lifting means connected to each of the opposite sides of the levers and tending by a pull thereon to shift the levers to operate the jaws to grip an article.

' RAYMOND I-I. BATES.

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