US3339915A

US3339915A - Method and apparatus for handling ferromagnetic sheets

Info

Publication number: US3339915A
Application number: US465933A
Authority: US
Inventors: Ricard Maurice
Original assignee: Cefilac SA
Current assignee: Cefilac SA
Priority date: 1964-06-26
Filing date: 1965-06-22
Publication date: 1967-09-05
Anticipated expiration: 1984-09-05
Also published as: BE665497A; FR1407842A; CH447995A

Description

Spt. 5, 1967 M. RICARD- 3,339,915

METHOD AND APPARATUS FOR HANDLING FERROMAGNETIC SHEETS Filed June 22, 1965 INVENTOR Maurice Ricard ATTORNEYS United States Patent C) 6 Claims. (a. 271-18) The present invention relates to a method and apparatus for handling ferromagnetic metal sheets, particularly sheets having some substantial flexibility. The object of the invention is to provide an improved method and apparatus for transferring such sheets from a first location to a second location.

The sheets to be handled usually come in stacks. The method and apparatus of the invention provides for unstacking them one by one and transferring them from the location of the stack to another location.

In the description which follows, the term tail end is applied to the end of the sheet, or of the stack, which is nearest to the second location (to which the sheets are transferred), and the term head end to the end farthest from it. Preparatory to being transferred, the sheets are usually separated by a so-called fanner which by magnetic action holds the sheets slightly apart on one or more sides. Pneumatic devices are also in use which facilitate the separation of the sheets as they are being gripped without first fanning them out.

Heretofore gripping has often been by pneumaticallyoperated suction cups or by magnetic elements at the tail end. Moving has been by means of pinch rolls which first engage the tail end of the sheet, or by means of magnetic conveyers, such as rolls or a conveyer belt. These devices have the drawback that the sheet Will rub against the succeeding sheet as it is being moved. To overcome this drawback, the gripping devices have been increased in number and distributed over the entire sheet surface, with corresponding complications in the installation.

The use of gripping devices which engage the sheet at its tail end or over its entire length has the further disadvantage that the duration of the complete cycle is practically equal to the sum of the gripping and moving times. Before the transfer system is able to engage a sheet, the preceding sheet must have been moved clear of the unstacking or gripping area. Thus the gripping and moving times are cumulative. Moreover, when the individual sheets are separated by a magnetic fanner, the downward attraction exerted by it must be overcome when the sheets are moved above it.

The invention provides an improved apparatus, and improved method, for transferring flexible sheets of ferromagnetic metal from a first location to a second location, which overcomes the foregoing disadvantages. The apparatus comprises a conveyer disposed above and spaced from and extending between the two locations. The magnet associated with the conveyer establishes a magnetic field in the space between the conveyer and said locations. Means are provided for lifting the head end portion of the flexible sheets, one at a time, from the first location to a position within the magnetic field where the lifted end portion of the sheet is magnetically attracted into engagement with the conveyer, and successive portions of the sheet thereupon become magnetically attracted into engagement with the conveyer until the entire sheet is held magnetically in contact with the conveyer against the force of gravity. Means are provided for moving the conveyer from above the first location to the second location, whereby the sheet which is magnetically held by the conveyer is transferred from a position above the first location to the second location. The conveyer in the vicinity of the second location advances the sheet beyond that region of the magnetic field wherein the metal of the sheet is magnetically supported against the force of gravity, and in consequence the sheet is progressively released from the conveyer and successive portions thereof dropped to the second location as the sheet is advanced over the second location by the conveyer.

The method of the invention, which is employed in operation of the above described apparatus, involves establishing a magnetic field which extends from above the first location to near the second location between which the sheets are to be transferred. The head end portion only of the sheets, one at a time, is lifted from the first location to a position within the magnetic field where such lifted end portion is magnetically supported against the force of gravity. Thereupon successive portions of the sheet become magnetically attracted into said field until the entire sheet is supported magnetically above the first location. While thus supported the sheet is transferred to above the second location. There the sheet is advanced beyond the region of the magnetic field where the sheet is supported against the force of gravity, and in consequence successive portions of the sheet are dropped to said second location until the entire sheet is there deposited.

There may be one continuous zone of magnetic attraction that extends in both the longitudinal and transverse directions; or there may be a number of more limited zones of attraction which are distributed longitudinally and/or transversely, provided that the sum of their partial effects upon the sheet is the same as the effects of a continuous zone.

In accordance with the invention, the gripping system is able to move toward and into engagement with a sheet while the preceding sheet is still being transferred, with the result that the duration of a cycle is substantially less than the sum of the gripping and moving times. The unstacking rate can thus be considerably increased.

A feature of the invention is that the spacing between two sheets being transferred on the conveyer may be varied simply by adjusting the gripping rate. The arrangement may even be such that two successive sheets overlap over a given length that is adjustable over a wide range. This is of interest in feeding a variety of machines, and particularly certain reheating furnaces. This feature permits dispensing with intermediate conveyers whose sole function is to regulate spacing between sheets.

The invention also makes it possible, by simple adjustment of the operating rate and stroke of a plurality of gripping devices serving a single conveying means, to feed one machine from several stacks of sheets of different sizes while maintaining the spacing between two consecutive sheets constant.

In a preferred and complete form the apparatus of the invention is used in association with an elevator table on which the sheets are stacked, and with a sheet fanner, Which may be either magnetic or pneumatic, at the head end of the stack to fan out the head end portion of at least the uppermost sheets in the stack.

The lifting means advantageously is capable of upward and downward motion. It may, for example, consist of a magnetic roll turning freely on its shaft, the direction of its field being radial at each point on its periphery and thus normal to the sheet at the point of contact. Thus there will be no need to impart a rocking motion to it but merely an alternating downward and upward movement.

The conveyer advantageously is a belt conveyer. The field holding the sheet on the conveyer may be produced, for example, by one or more longitudinal, fixed magnetic rails disposed above the conveyer belt, i.e., directly above the lower course of the belt, to the lower surface of which the sheet is to be held. However, the magnetic field may also be generated by the conveyer itself, if the latter is magnetic, or by a series of magnetic rolls.

In the drawings, FIGS. 1 to 4 show the application of the invention schematically, and illustrate successive stages in the handling of a sheet in accordance with the invention.

The apparatus comprises an elevator table 1, a stack of sheets 2 at a first location, and a fanner 3 by which the head end portion of the uppermost sheets are fanned out. The second location to which the sheets are to be transferred is at 4. A vertically movable magnetic lifting roll -5 is located adjacent the head end of the stack 2 in position to engage the fanned out end pontions of the sheets. Lifting magnet 6, including a magnetic roll 7, generate a magnetic field which, down to the limit indicated by the broken line 8, is sufliciently strong to support a sheet from the stack 2 against the force of gravity. A conveyer belt 9 passes around the magnetic roll 7 and another nonmagnetic supporting roll 10 which is driven by means not shown in the direction of the arrow.

When one of the sheets from the stack 2 is brought within the region of the magnetic field indicated by the broken line 8, it is supported against the force of gravity in contact with the lowermost surface of the lower course 9a of the conveyer belt and by the movement of that belt is transferred to above the second location at 4. FIG. 1 shows such a sheet 11 which is being advanced by the conveyer beyond the region of the magnetic field where the sheet is supported against the force of gravity. As it passes beyond such region, successive portions of the sheet drop from the conveyer to the second location.

As shown in FIG. 2, the magnetic lifting roll 5, after having been lowered to the position shown in dotted lines to engage the uppermost of the fanned out end portions of the sheets 12, has lifted such sheet from the stack 2 and has brought the portion from A to B into the zone of attraction of the magnetic field wherein the force of gravity is overcome. The sheet is then attracted progressively and very rapidly over its entire length to the conveyer by a deformation which spreads from the head end to the tail end. Successive positions of the sheet are shown in FIG. 3. The solid line ABCDEF shows a first position assured by the sheet 12, and then it rapidly deforms through succeeding positions (such as those shown in dashed lines in FIG. 3) ABC'DEF, ABC'D'EF and ABCD'E'F, until it is flat against the underside of the conveyer as shown in FIG. 4. In the final position shown in FIG. 4, the sheet is advanced by the conveyer belt to above the second location, when it will be released as shown in FIG. 1.

The sheet may be released from the lifting roll either 'by being rolled therefrom; or the magnetic field of the lifting roll may be momentarily shut off. The lifting roll may begin its descent to engage the next sheet before the preceding sheet has been advanced wholly beyond the location of the stack 2.

I claim:

1. Apparatus for transferring flexible sheets of ferromagnetic metal from a stack at a first location to a second location comprising (1) a movable conveyer disposed above and spaced from and extending between said locations,

(2) magnets associated with said conveyer,

(a) said magnets establishing a magnetic field in the space between the conveyer and said locations,

(3) means for lifting, in the topmost sheet in said stack, the end of said topmost sheet remote from said second location into a position within said field where the lifted end of said sheet is magnetically attracted into engagement with said conveyer and successive portions of said sheet progressing toward the end of said sheet adjacent said second location thereupon become magnetically attracted into engage ment with said conveyer until the entire sheet is held magnetically in contact with the conveyer against the force of gravity, and

(4) means for moving said conveyer from above said first location to a position higher than and adjacent to said second location.

2. Apparatus according to claim 1 in which the con- 'veyer is a belt conveyer and the magnets are disposed in close proximity to the conveyer belt above the surface thereof engaged by the magnetically supported sheets.

3. Apparatus for transferring flexible sheets of ferromagnetic metal one by one from a stack of said sheets disposed at a first location to a second location comprismg (l) a conveyer belt disposed above and spaced from and extending between said locations,

(2) magnets disposed above said conveyer belt,

(a) said magnets establishing a magnetic field in the space between the conveyer and said first location,

(3) means adjacent the end of said stack remote from said second location for fanning out, in at least the uppermost sheets in the stack, the end portions thereof remote from said second location,

(4) reciprocable lifting means mounted in position to engage the uppermost of the fanned out end portions of the stack of sheets and to lift such end portion to a position within said field where it is magnetically attracted into engagement with the conveyer belt and successive portions of the uppermost sheet progressing toward the end thereof adjacent said second location thereupon become magnetically attracted into engagement with said belt until the entire sheet is held magnetically against the force of gravity in engagement with the underside of the conveyer belt, and

(5) means for moving said conveyer belt through a path of travel from above said first location to a position higher than and adjacent to said second location.

4. The method of transferring flexible sheets of ferromagnetic metal from a stack at a first location to a second location which comprises (1) establishing a magnetic field extending from a position higher than and adjacent to said first location to above said second location,

(2) lifting, in the topmost sheet of the stack, that end portion only which is remote from said second location to a position within said field where the lifted end Portion of said sheet is magnetically supported against the force of gravity and wherein successive portions of said sheet progressing toward the end of said sheet adjacent said second location thereupon become magnetically attracted into said field until the entire sheet is supported magnetically above said first location,

(3) transferring said sheet while thus supported to a position higher than and adjacent to said second location, and

(4) advancing said sheet toward said second location beyond the region of said magnetic field where the sheet is supported against the force of gravity,

(a) whereby successive portions of said sheet beginning with the end thereof farthest from said first location are dropped onto said second location until the entire sheet is there deposited.

5. The method of transferring flexible sheets of ferromagnetic metal one by one from a stack of said sheets disposed at a first location to a second location which comprises (1) establishing a magnetic field extending from above said first location to a position higher than and adjacent to said second location,

(2) fanning out, from at least the uppermost sheets of said stack, the end portions thereof remote from said second location,

(3) lifting the fanned out end portion only of the uppermost of the sheets in the stack to a position Within said field Where the lifted end portion of said sheet is magnetically supported against the force of gravity and successive portions of said sheet progressing toward the end of said sheet adjacent said second location thereupon become attracted into said field until the entire sheet is supported magnetically above said first location,

(4) transferring said sheet while thus supported to a position higher than and adjacent to said second location, and

(5) advancing said sheet toward said second location beyond the region of said magnetic field where the sheet is supported against the force of gravity,

(a) whereby successive portions of said sheet be- References Cited UNITED STATES PATENTS Free 271-18 Gerhardt 271l8 Chatterton 271-18 "Powers 271-18 Hommel 271-18 Parke et a1 271-74 0 M. HENSON WOOD, JR., Primary Examiner.

ALLEN N. KNOWLES, Examiner.

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No 3 ,339 ,915 September 5 1967 Maurice Ricard rror appears in the above numbered pat- It is hereby certified that e s Patent should read as ent requiring correction and that the said Letter corrected below.

Column 4, lines 47 to 49, for "a position higher than and ad acent to said first location to above" read above said first location to a position higher than and adjacent Signed and sealed this 22nd day of October 1968.

(SEAL) Attest:

EDWARD J. BRENNER Commissioner of Patents Edward M. Fletcher, Ir.

Attesting Officer

Claims

1. APPARATUS FOR TRANSFERRING FLEXIBLE SHEETS OF FERROMAGNETIC METAL FROM A STACK AT A FIRST LOCATION TO A SECOND LOCATION COMPRISING (1) A MOVABLE CONVEYER DISPOSED ABOVE AND SPACED FROM AND EXTENDING BETWEEN SAID LOCATIONS, (2) MAGNETS ASSOCIATED WITH SAID CONVEYER, (A) SAID MAGNETS ESTABLISHING A MAGNETIC FIELD IN THE SPACE BETWEEN THE CONVEYER AND SAID LOCATIONS, (3) MEANS FOR LIFTING, IN THE TOPMOST SHEET IN SAID STACK, THE END OF SAID TOPMOST SHEET REMOTE FROM SAID SECOND LOCATION INTO A POSITION WITHIN SAID FIELD WHERE THE LIFTED END OF SAID SHEET IS MAGNETICALLY ATTRACTED INTO ENGAGEMENT WITH SAID CONVEYOR AND SUCCESSIVE PORTIONS OF SAID SHEET PROGRESSING TOWARD THE END OF SAID SHEET ADJACENT SAID SECOND LOCATION THEREUPON BECOME MAGNETICALLY ATTRACTED INTO ENGAGEMENT WITH SAID CONVEYOR UNTIL THE ENTIRE SHEET IS HELD MAGNETICALLY IN CONTACT WITH THE CONVEYER AGAINST THE FORCE OF GRAVITY, AND (4) MEANS FOR MOVING SAID CONVEYER FROM ABOVE SAID FIRST LOCATION TO A POSITION HIGHER THAN AND ADJACENT TO SAID SECOND LOCATION.