US 3581873 A
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United States Patent Inventor Heinrich Spodig Netterberge 84, 471 l Bork, Germany Appl. No. 750.918 Filed Aug. 7, I968 Patented June I, 1971 Priority Aug. 10, 1967 Germany P 15 56 183.8
ENDLESS MAGNETIC CONVEYOR 6 Claims, 7 Drawing Figs.
US. Cl 198/41 Int. Cl B6 Sg 17/46 Field of Search 198/41 56] References Cited UNITED STATES PATENTS 2,881 ,90! 4/1959 Zimmer 198/41 3,308,925 3/1967 Alfredeen 198/41 Primary Examiner-Even C. Blunk Assistant Examiner-Alfred N Goodman Attorney-Michael S. Striker ABSTRACT: Endless magnetic conveyor comprising a belt, a support structure therefore, a magnet system disposed in said support structure, and means for revolving said belt about said support structure, the belt being formed of a magnetic material and having an active cross section relative to the flux of said magnet system adapted to provide a magnetic stray flux over and above saturation so that a holding action may be exerted on articles placed on said belt.
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I FIG] INVENTOR [If/M210! s ay/c ENDLESS MAGNETIC CONVEYOR CROSS-REFERENCES TO RELATED APPLICATIONS Two applications of the-same inventor are concurrently filed herewith relating to Permanent Magnet Holding Device and Permanent Magnet Device For Holding or Conveying Purposes respectively.
BACKGROUND OF THE INVENTION The invention relates to an endless magnetic belt conveyor, such as are used in magnetic conveyors, wherein the belt revolves around a magnet system disposed in the support structure. The magnetic field of force in this kind of device extends transversely to the direction of movement of the belt.
. The belt in the conventional device is formed of a nonmagnetic material to prevent a short circuit of the magnet system by the belt which would cancelout the holding power of the system. The magnetic lines of force in this kind of device penetrate the nonmagnetic material of the belt and the ferromagnetic articles which may be placed on the belt form the return conductor for the lines of force. These articles will be subject, more or less, to magnetic saturation depending on the mass of iron present in relation to the flux of the magnet system. The magnetic attraction is effected thus without direct contact between the article and the magnet system. The lines of force must bridge the distance resulting from the thickness of the belt and its spacing from the magnet system. Accordingly, and depending on this distance, there takes place an only partial utilization of the available coercive force of holding power of the magnet system and the system must therefore be built to larger specification than would be necessary for the holding action proper.
SUMMARY OF THE INVENTION The invention has the object to avoid these shortcomings of present endless conveyor belts for magnetic conveyors. It has in particular the object to improve the utilization of the holding power of the magnet system in a magnetic conveyor.
This is accomplished by an endless magnetic conveyor comprising a belt, a support structure therefore, a magnet system disposed in said support structure, and means for revolving said belt about said support structure, the belt being formed of a magnetic material and having a mass and volume relative to the flux of said magnet system adapted to provide a magnetic stray flux over and above saturation so that a holding action may be exerted on articles placed on said belt. It is thus of the essence of the present invention that the conveyor belt consist of a magnetic material, and that the belt is magnetized to saturation and that beyond this a magnetic field of force or stray flux be created-to efiect the holding action on the workpiece. The conveyor belt in this device is in a partial magnetic short circuit and when the workpiece is placed in direct magnetic contact with the'belt the magnetic stray flux emanating from the belt is included through the workpiece in this partial magnetic short circuit.
The flow of force is therefore greatly increased and the holding power is improved several times. The invention furthermore accomplishes an improved use of the input of magnetic energy as compared with conveyor belt devices with nonmagnetic belts.
The novel features which are considered as characteristic BRIEF DESCRIPTION OF THE DRAWING FIG. l'of the drawing shows, in diagrammatic form and cross section, a first embodiment of the belt conveyor of the invention;
FIG. 2 is a partial plan view, likewise in diagrammatic manner, of the belt consisting of linked plates employed in the conveyor of FIG. 1;
FIG. 3 is a partial plan view of another embodiment wherein links of steel wire are employed as the belt together with a roller chain drive mechanism;
FIG. 4 illustrates diagrammatically another embodiment of the invention wherein a sheet metal strip is employed as the belt;
FIG. 5 illustrates, in diagrammatic manner, a similar embodiment as FIG. 4 but including a basefor the sheet metal strip;
FIG. 6 illustrates, in diagrammatic cross section, another embodiment of the invention wherein parts of rollers are used for the movement of the belt; and
FIG. 7 is a similar illustration of a different embodiment wherein ball bearings are employed to support the belt.
DESCRIPTION OF THE PREFERRED EMBODIMENTS With reference to FIG. 1 of the drawing it will be noted that the conveyor in conventional manner comprises a support structure consisting of two interconnected brackets l and 2 which carry the magnet system 15 providing for a north and south pole at the center of the travel path. The belt 3 following the concept of the invention is formed of magnetic material and more specifically in the embodiment illustrated in FIGS. 1 and 2 in the form of individual slats 4 which are provided with a thin nonmagnetic base 5 and are interconnected by links 6.
The volume and mass of the belt 3 are selected in relation to the power of the magnet system to subject the belt section disposed at each particular moment of time above the magnet system to a partial magnetic circuit and to cause its magnetic saturation and beyond that to cause it to retain a magnetic field of force or stray flux. This stray flux will form part of the partial short circuit formed across the ferromagnetic article placed on the belt. There is thus accomplished an improvement of the optimum magnetic flux and therefore a better utilization of the holding power of the magnet system. This will in particular be noticeable in case of articles of small ferromagnetic cross section, such as, thin-walled tin cans. Such tin cans will be held safely on the conveyor even when filled.
FIG. 3 illustrates a different embodiment where wire mesh links 7 are employed instead of the conveyor consisting of slats 4. The wire mesh may be driven by laterally provided roller chains 8. FIG. 4 shows another embodiment with a belt formed of a sheet metal strip 9. The strip may either be directly imposed upon the magnet system or it may be provided with a nonmagnetic base 10 to reduce friction. The base is shown in FIG. 5. It will be understood that the base may either be applied to the belt 3 or that it may be rigidly secured to the magnet system 15 as far as the latter extends.
It is of course also possible to support the belt 3, no matter which particular form it may have, on rotating members for movement across the magnet system 15. This is illustrated in FIG. 6 where the support bodies are in the form of pairs of rollers Ill provided in the support structure of the conveyor and consisting of magnetic material. The belt 3 rests upon the rollers and will move by rolling on them.
A similar structure is illustrated in FIG. 7 where, however, ball bearings are employed consisting of balls 12 and journals therefor in the magnet system 15. The journals may also be in the general support structure.
It will be manifest that no matter what embodiment is chosen the belt 3 must consist of magnetic material and must have an active ferromagnetic cross section relative to the magnetic flux of the magnet system 15 permitting the portion of the belt 3 above the magnet system 15 at each moment of time to maintain a stray field of force over and above its magnetic saturation.
. It will be understood that each of the elements described above, or two or more together, may also find a useful application in other types of constructions differing from the types described above.
While the invention has been illustrated and described as embodied in an endless magnetic conveyor, it is not intended to be limited to the details shown, since various modifications and structural changes may be made without departing in any way from the spirit of the present invention.
Without further analysis, he foregoing will so fully reveal the gist of the present invention that others can by applying current knowledge readily adapt it for various applications without omitting features that, from the standpoint of prior art, fairly constitute essential characteristics of the generic or specific aspects of this invention and, therefore, such adaptations should and are intended to be comprehended within the meaning and range of equivalence of the following claims.
What I claim as new and desire to be protected by Letters Patent is set forth in the appended claims.
1. An endless magnetic conveyor comprising a belt consisting of a nonmagnetic base and a magnetic sheet metal strip fastened to said nonmagnetic base, said belt having a width which is a multiple of its thickness and having an upper run provided with an upper support face adapted to support magnetizable articles thereon; a support structure supporting said belt; and a magnet system disposed in said support structure and located closely adjacent to and beneath said upper run for magnetic saturation of said magnetic sheet metal strip of said upper run of said belt to provide magnetic stray flux extending over said support face of said belt so as to exert a holding action on articles placed on said support face.
2. The endless conveyor device of claim I, wherein the belt forms part of a partial magnetic short circuit, the said magnetic stray flux likewise being embraced by said magnetic short circuit.
3. The endless conveyor device of claim 1, wherein the belt consists ofa plurality of slats connected by linkages.
4. The endless conveyor device of claim 1, wherein the belt consists of chain links and which includes roller chains for revolving the belt.
5. The endless conveyor device of claim 1 which includes rotating means for supporting said belt, the said rotating I means consisting of magnetic material and being supported in said magnet system.
6. The endless conveyor device of claim 5, wherein the rotating support means consist of ball bearings.