US3799602A

US3799602A - Apparatus for handling material

Info

Publication number: US3799602A
Application number: US00329984A
Authority: US
Inventors: W Laws; E Hyde
Original assignee: British Iron and Steel Research Association BISRA
Current assignee: British Iron and Steel Research Association BISRA
Priority date: 1972-02-23
Filing date: 1973-02-06
Publication date: 1974-03-26
Anticipated expiration: 1991-03-26
Also published as: JPS4894142A; DE2308513A1; IT977829B

Abstract

An apparatus is described for use in converting an electromagnetic grab to function as a mechanical grab. The apparatus includes a frame within which the magnet block of a conventional electro-magetic grab is locatible and a two part core assembly of magnetic material hydraulically coupled to the grab arms of the apparatus. Energisation of the magnet block causes progressive movement of the core assembly towards the block actuating closing movement of the arms, whilst a hydraulic reservoir assists in procuring movement of the arms after de-energisation of the magnet block.

Description

United States Patent [191 Laws et a1.

[ APPARATUS FOR HANDLING MATERIAL [75] Inventors: William Robert Laws, Worcester 7 Park; Erie Ambrose Hyde, Hayes,

both of England [73] Assignee: The British Iron and Steel Research Association, London, England [22] Filed: Feb. 6, 1973 [21] App]. No.: 329,984

[30] Foreign Application Priority Data Feb. 23,1972 Great Britain 8379/72 [52] US. Cl 294/88, 294/655, 294/106, 214/114, 214/147 G [51] Int. Cl. B666 1/06, B666 3/16 [58] Field of Search 294/655, 88, 106; 37/183 R,183 A, 187; 214/147 G, 114;

[56] 1 References Cited UNITED STATES PATENTS Naugle et a1 H 214/114 Mar. 26, 1974 2,651,538 9/1953 Stahmer 294/655 2,850,189 9/1958 Leroy 214/114 FOREIGN PATENTS OR APPLICATIONS 958,539 5/1964 Great Britain, 294/655 188,832 11/1922 Great Britain 294/655 Primary Examiner--Evon C. Blunik Assistant Examiner-John ny D. Cherry Attorney, Agent, or Firm-Bacon & Thomas 5 7 ABSTRACT An apparatus is described for use in converting an electro-magnetic grab to function as a mechanical grab. The apparatus includes a frame within which the magnet block of a conventional electro-magetic grab is locatible and a two part core assembly of magnetic material hydraulically coupled to the grab arms of the apparatus. Energisation of the magnet block causes progressive movement of the core assembly towards the block actuating closing movement of the arms, whilst a hydraulic reservoir assists in procuring movement of the arms after de-energisation of the magnet block.

6 Claims, 4 Drawing Figures PATENIEUMARZS mm 37991502 SHEETIUFZ FIG).

AV///K\V /A\7// AV AV///AV AV/ FIG. 3.

APPARATUS FOR HANDLING MATERIAL Apparatus has already been proposed for handling material such as scrap metal by modifying a conventional magnet block suspended from a crane. Accordy from the problem that the attractive force between the core and the block varies as the inverse square of the distance between them so that the closing force on the arms is smallest when the arms are in the fully open position. Consequently when handling a large and heavy load the attractive force of the magnet block may sometimes be insufficient to start the closing movement of the arms. An object of this invention is to reduce this problem.

According. to the present invention there is provided apparatus attachable to an electro-magnetic grab for handling non-magnetic materials including: a frame connectible to. the grab, lifting arms movable relative to the frame, and a core movable relative to the frame, the arms and the core being operatively connected together so that, in use, when the frame is connected to the grab, energisation of the magnet block of the grab will attract the core towards the block thus closing the armsinto a material-holding position, subsequent deenergisation of the block allowing the arms to open into a fully open material-releasing position, the core being formed in two parts of magnetic material capable of limited relative movement, the parts being arranged so that'in the'fully open position of the arms the first part is located closer to the magnet block than the second part, movement of said first part towards the block carrying said second part towards the block and partially closing the arms, the said second part being capable of further movement towards the block after the first part has moved its full extent in order to complete the closing movement ofthe arms.

By forming the core in at least two parts in accordance with the invention the distancesbetween one core part and the block can be kept sufficiently small to ensure an adequate attractive force to begin the closing movement of the arms. Movement of the other part relative to the first part towards the block enables full closing'movement of the arms to take place.

Although the operative connection betweenthe core assembly and the arms may be a simple mechanical connection, preferably the second part of the core assembly is connected to a piston and cylinder assembly arranged so that upon movement of said second part towards the magnet block fluid is displaced to actuate fluid operated rams connected to the arms. Such a hydraulic connection enables the small amount of movement of the core assembly to be conveniently translated into a large movement of the arms.

Upon de-energisation of the magnet block there is residual magnetism left in the block which will hold the core parts close to the magnet block unless the separatingforces can overcome this. Accordingly it may be desirable to have a pressurisable fluid reservoir operatively connected to the rams in such a way that upon closing movement of the arms fluid is displaced into the reservoir thus producing a force tending. to open the arms when the magnet blockis de-energised. This force, which could be supplemented by a mechanical spring, helps to overcome the residual magnetic force.

The two parts of the core assembly can be arranged in any suitable way. The first part is preferably rigidly connected to a first sleeve slidable on a pillar extending FIG. 1 shows a conventional electro-magnetic grab consisting of a crane 1 from which hangs a hook 2 on which a magnet block 3 is suspended by chains 4. For picking up magnetic material such as steel scrap the block is electrically energised to attract the magnetic material and upon de-energisation the scrap will be dropped. Apparatus 5 for adapting the electromagnetic grab for the handling of non-magnetic material such as non-magnetic metal scrap is shown on the ground before being connected to the grab.

The apparatus 5 includes a frame 6 at the top of which there is a recess 7 into which the magnet block 3 can be inserted upon relative lateral movement between the block 3 and frame 6. The top of the frame 6 has an annular plate 8 with an opening 9 which forms a passage for the chains 4 when the block 3 is being in serted into the frame 6. The frame 6 is formed by the plate 8, a wall 10, four plates 15 connected to the wall 10, a ring 11 connected to the bottom of the wall 10, and a bottom member 12 connected to the plates 15.

Four curved lifting arms 13 are pivotally connected to the plates 15 of the frame 6 by pivot pins14. A core assembly 16 of magnetic material such as soft iron is slidably mounted within the frame 6 on a pillar 17 connected to the bottom member 12 and extending vertically within the frame 6. The core assembly 16 is formed intwo parts 18 and .19. The first part 18 is rigidly connected to a first sleeve 20 surrounding and slidable on the pillar 17. The second part 19 is rigidly connected by arms 22 to a second sleeve 21 surrounding the first sleeve 20 and slidable relative to the first sleeve 20. The first part 18 is formed of two rings rigidly connected together, and surrounding the pillar 17, and the second part 19 is also formed of two rings rigidly connected together and surrounding the first part 18.

A stop 23 connected to the pillar 17 limits downward movement of the sleeve 20. In use, upward movement of the sleeve 20 is limited by contact of the first part 18 with the magnet block 3. A projection 24 on the sleeve 20 limits downward movement of the sleeve 21 on the sleeve 20, and in use upward movement of the sleeve 21 on the sleeve 20 is limited by contact of the second part 19 .with the magnet block 3.. As shown in FIG. 4 when the sleeve 20 is in contact with the stop 23 and when the sleeve 22 is in contact with the projection 24 the upper surface of the part 18 is higher than the upper surface of the part 19.

A rubber bellows 25 is connected between the stop 23 and the lower end of the sleeve 21 to seal the assembly 16 against dirt. A rubber bellows 26 is connected between the upper end of the pillar 17 and the sleeve 20, and a further bellows 27 is connected between the upper end of the sleeve 21 and the lower side of the core part 18 also to seal the assembly 16 against dirt.

The arms 13 and the core assembly 16 are operatively connected so that movement of the core assembly 16 towards the magnet block 3 closes the arms 13 into a material holding position. A piston and cylinder assembly 28 is connected between the arms 22 of the core assembly 16 and the frame 6 adjacent to each arm 13, and a hydraulic ram 29 interconnects each arm 13 and the frame 6. The piston rod end of each assembly 28 is pivoted to the arm 22 and the piston rod end of each ram 29 is pivoted to its associated arm 13. A pressurisable reservoir 30 for hydraulic fluid is disposed within the pillar 17 and a hydraulic lead 31 connects the reservoir with the piston rod end of the cylinder of each ram 29. A hydraulic lead 32 connects the other end of the cylinder of each ram 29 with the piston rod end of the'associated cylinder 28.

When not in use the apparatus stands on its arms 13 with-the arms 13 open as shown in FIGS. 1 and 4 and the right hand side of FIG. 3. The crane driver can easily engagethe apparatus 5 with the magnet block 3. As shown in FIG. 4 the core part 18 is closer to the magnet block 3 than the core part 19. The crane 2 can lift the apparatus 5 and lower it on to a pile of nonmagnetic scrap. The weight of the apparatus 5 and the block 3 force the arms 13 into the scrap until the member 12 rests on the scrap. The block 3 is then energised whereupon the core part 18 is first attracted to its upper position into contact with the block 3. During this upward movement of the part 18 the part 19 is carried towards the block 3 because the sleeve 21 is in contact with the projection 24. This upward movement of the part 19 together with the part 18 results in a partial extension of the piston and cylinder assemblies 28 so that hydraulic fluid is displaced via leads 32 partically to extend the rams 29. When the core part 18 has moved its full extent and is in contact with the block 3, the second part 19 will be close enough to the block 3 to be attracted towards it and this further movement of the part 19, during which the sleeve 21 will slide on the sleeve 20, results in more hydraulic fluid being displaced from the cylinder assemblies 28 into the rarns 29.

Displacement of fluid into the rams 29 from the lead 32 has two effects. First the arms 13 move into the closed position, and second, fluid is displaced from the rod end of the cylinders of the rams 29 into the reservoir 30. The reservoir effectively stores energy during movement of the arms 13 to the closed position so that upon de-energisation of the magnet block 3 a force is exerted tending to move the core assembly away from the magnet block 3.

When the arms 13 are closed the crane 1 can lift the magnet block 3 together with the apparatus 5 and scrap. When the magnet block 3 is de-energised the weight of the scrap and the core assembly 16 provides a moment about the pivots 14 to open the arms and release the scrap. The force produced by the reservoir 30 will add to the moment and will help to overcome any residual magnetic force which, with a light load in the arms 13, might otherwise prevent the arms 13 from opening.

The apparatus described above enables a conventional electro-magnetic grab to be quickly modified for use with non-magnetic materials. However, the apparatus could be permanently attached to a magnetic block. The provision of the cores assembly in two parts as described enables heavier loads to he lifted than could be lifted otherwise.

We claim 1. Apparatus attachable to an electro-magnetic grab for handling non-magnetic materials including: a frame connectible to the grab, lifting arms movable relative to the frame, and a core movable relative to the frame, the arms and the core being operatively connected together so that, in use, when the frame is connected to the grab, energisation of the magnet block of the grab will attract the core towards the block thus closing the arms into a material-holding position, subsequent deenergisation of the block allowing the arms to open into a fully open material-releasing position, the core being formed in two parts of magnetic material capable of limited relative movement, the parts being arranged so that in the fully open position of the arms the first part is located closer to the magnet block than the second part, movement of said first part towards the block carrying said second part towards the block and partially closing the arms, and said second part being capable of further movement towards the block after the first part has moved its full extent in order to complete the closing movement of the arms.

2. Apparatus as claimed in claim 1 in which said second part is connected to a piston and cylinder assembly arranged so that upon movement of said second part towards the magnet block fluid is displaced to actuate fluid operated rams connected to the arms.

3. Apparatus as claimed in claim 2 including a pressurisable fluid reservoir operatively connected to the rams in such manner that, upon closing movement of the arms, fluid is displaced into the reservoir producing a force tending to open the arms when the magnet block is de-energised.

4. Apparatus as claimed in claim 3 in which said first part of the core assembly is rigidly connected to a first sleeve slidable on a pillar extending within the frame.

5. Apparatus as claimed in claim 4 in which said second part is rigidly connected to a second sleeve slidably mounted relatively to said first sleeve.

6. Apparatus as claimed in claim 4 wherein said pressurisable reservoir is disposed within said pillar.

Claims

1. Apparatus attachablE to an electro-magnetic grab for handling non-magnetic materials including: a frame connectible to the grab, lifting arms movable relative to the frame, and a core movable relative to the frame, the arms and the core being operatively connected together so that, in use, when the frame is connected to the grab, energisation of the magnet block of the grab will attract the core towards the block thus closing the arms into a material-holding position, subsequent de-energisation of the block allowing the arms to open into a fully open material-releasing position, the core being formed in two parts of magnetic material capable of limited relative movement, the parts being arranged so that in the fully open position of the arms the first part is located closer to the magnet block than the second part, movement of said first part towards the block carrying said second part towards the block and partially closing the arms, and said second part being capable of further movement towards the block after the first part has moved its full extent in order to complete the closing movement of the arms.