US2999687A

US2999687A - Sheet feeder

Info

Publication number: US2999687A
Application number: US782543A
Authority: US
Inventors: William B Hommel
Original assignee: American Can Co
Current assignee: Primerica Inc
Priority date: 1958-12-23
Filing date: 1958-12-23
Publication date: 1961-09-12
Anticipated expiration: 1978-09-12

Description

Sept. 12, 1961 w. B. HOMMEL SHEET FEEDER 3 Sheets-Sheet 1 Filed Dec. 23, 1958 INVENTOR.

I/V/LL/AM B. HOMMEL BY Ma 4%, MQQAL A T TUBA/[V5 3 Sheets-Sheet 2 INVENTOR.

W/L L/AM 5. HOMMEL SHEET FEEDER w. B. HOMMEL Se t. 12, 1961 Filed Dec. 23, 1958 Sept. 12, 1961 w. B. HOMMEL 2,999,687

SHEET FEEDER Filed Dec. 25, 1958 5 Sheets-Sheet 3 IN VEN TOR.

WILL/14M B. HDMMEL A 7 TOENEYS 2,999,687 SHEET FEEDER William B. Hommel, Penn Yan, N.Y., assignor to American Can Company, New York, N.Y., a corporation of New Jersey Filed Dec. 23, 1958, Ser. No. 782,543 4 Claims. (Cl. 271-18) The present invention relates to machines for feeding individual sheets of metal from or onto a stack of such sheets and has particular reference to devices for magnetically separating the sheets one from another and for suspending a single sheet for feeding.

An object of the instant invention is to provide for the complete separation of an individual sheet from a stack of such sheets and for the uniform suspension of the sheet free from all other sheets in a manner which holds the suspended sheet against sagging to facilitate the feeding of the suspended sheet along a path of travel for a subsequent operation.

Another object is to effect such separation and suspension of individual sheets at high speed so as to adapt machinery for this purpose to modern high speed can manufacturing lines.

Another object is to effect such sheet separation and suspension magnetically in a manner which produces high efiiciency and low maintenance costs.

Numerous other objects and advantages of the invention will be apparent as it is better understood from the following description, which taken in connection with the accompanying drawings, discloses a preferred embodi ment thereof.

Referring to the drawings:

FIGURE 1 is a top plan view of a sheet feeding machine embodying the instant invention, with parts omitted and parts shown in dotted lines;

FIG. 2 is an end view of the machine shown in FIG. 1, with parts broken away;

FIG. 3 is an enlarged sectional view as taken substantially along the broken line 3-3 in FIG. 1, with parts broken away;

FIG. 4 is a transverse sectional view as taken substantially along the line 44 in FIG. 1, with parts broken away; and

FIG. 5 is a schematic view of improved electro-magnet devices used in the machine and a wiring diagram showing how they are connected for operation.

As a preferred and exemplary embodiment of the instant invention the drawings illustrate principal parts of a sheet feeding machine of the character disclosed in United States Patent 2,221,981 issued November 19, 1940, to G. A. Martin on Sheet Feeder.

In such a sheet feeding machine, a stack A of metal sheets B, such as tinplate, black iron or the like sheets from which cans or containers are made, is placed in a magazine of the machine with the sheets in a horizontal relation. The sheets are individually removed from the top of the stack and fed horizontally away from the stack for a subsequent operation. The stack of sheets B is usually supported on a pallet 21 which is deposited on a vertically movable platform 22 in the machine.

Pairs of vacuum cups 24 are provided in the machine to grip the topmost sheet B and lift it bodily to a predetermined level above the stack to separate it from the Patented Sept. 12, 1961 ice others. The rear pair of cups then release the sheet and the forward pair carry it forward, horizontally into the bite of a pair of continuously rotating feed rollers 25 which take the sheet away from the vacuumcups and feed it away from the stack for a subsequent operation. During this feeding operation, the vacuum in the cups 24 is dissipated so as to free the sheet for feeding.

In order to insure that only single sheets are lifted free of the stack for feeding and to fully support the sheet during feeding, an improved magnet device is provided to completely separate the topmost sheet of the stack from the others and to hold this sheet in suspension while it is being fed.

The separation of the topmost sheet preferably is effected by a pair of spaced and parallel

magnet pole pieces

31, 32 of opposite polarity which constitute side magnets. These magnets are disposed on opposite sides of the stack A of sheets B and between which the sheets in the upper portion of the stack pass as the stack is gradually lifted as hereinbefore mentioned. These

pole pieces

31, 32 are disposed at the same level and extend for substantially the full length of the sheets in the stack. The

pole pieces

31, 32 are connected to

respective magnet cores

33, 34 of respective electro-

magnet coils

35, 36 which in turn are connected by

wires

37, 38 and 39, 40 (FIG. 5) to lead

wires

41, 42 of a suitable source of electric current such as a generator '43. A rheostat 44 is connected into the lead wire 42 to control the magnetic fluX of the

coils

35, 36.

The magnet cores 33, 34- extend along the back edges of the upper sheets B in the stack A as shown in FIGS. 1, 2, 3 and 5 and are connected to a pair of short pole I

pieces

45, 46 which constitute short back magnets having opposite polarity and having a polarity opposite to the

side magnets

31, 32.

Thus the

side magnets

31, 32 and the

back magnets

45, 46 cooperate with each other in setting up in the path of travel of the sheets, a plurality of magnetic fields called primary fields. These magnetic fields set up in the individual sheets themselves, adjacent their side and back edges, additional magnetic fields which act against each other to repulse adjacent sheets disposed between the magnets, and thereby force the sheets apart into a fannedout relation as shown in FIGS. 3 and 4, and thus effect the separation of the sheets as hereinbefore mentioned to facilitate removal of the sheets individually. For the purposes of this specification, the magnetic fields set up in this section of the apparatus by the

magnets

31, 32,. 45, 46 is known as a lower strata field zone.

The

side magnets

31, 32 and the

back magnets

45, 46 preferably are formed with straight vertical inner faces 48 (FIGS. 3 and 4). The upper edges of these magnets are beveled from the inner faces 48 outwardly toward the outer faces to provide an air gap or dead spot (FIG. 4) having a magnetic field of greatly reduced intensity as compared with the fields adjacent the faces 48 so as to restrict the level of the top sheet in the separated sheets in the upper portion of the stack.

When the vacuum cups 24 move down to pick up the top separated sheet they move down to a level slightly below this top sheet level to insure a grip on the top sheet. On the up stroke as the vacuum cups 24 lift the sheet, the outer edges of the top sheet drags against sharp pointed projections 49 (FIGS. 1, 3 and 4) in the

side magnets

31, 32 to insure against the cups 24 picking up more than one sheet if two or more cling together.

When the vacuum cups 24 reach the level of the feed line as shown in FIG. 3, the sheet is attracted to and is held in horizontal suspension by a pair of

pole pieces

51, 52 of opposite polarity and which constitute holding magnets. The

magnets

51, 52 are located between the

side magnets

31, 32 and are in parallelism with them and of opposite polarity to them but are disposed at a higher level. These

magnets

51, 52 extend for substantially the full length of the sheet, like the

side magnets

31, 32.

At the back of the stack A the

holding magnets

51, 52 are connected to the

cores

33, 34 on the inner sides of the

coils

35, 36 adjacent the back magnets 45, 46 (FIG; 1) so as to be of the same polarity as the back magnets. Intermediate their length, the top or

holding magnets

51, 52 are connected by a magnet core 54 of a magnet coil 55 which is connected by wires 56, 57 (FIG. to the

lead wires

41, 42 of the generator 43. A rheostat 58 is connected into the wire 57 to control the magnetic flux of the coil 55.

As a sheet B is attracted to the

holding magnets

51, 52 and while it is held in suspension thereby a secondary or auxiliary magnetic field disposed adjacent the side edges of the sheet induces its magnetic flux edgewise into the suspended sheet to set up in this sheet a repulsion magnetic field which repulses an adjacent sheet to insure the suspension of only a single sheet. This secondary magnetic field is produced by a pair of pole pieces 61, 62 (FIGS. 1, 2, 4 and 5) of opposite polarity and which constitutes upper strata magnets. The

upper strata magnets

61, 62 and located on top of the side magnets 31,- 32 and are of the same polarity as the side magnets as indicated in FIG. 4. The

magnets

61, 62 are substantially the same length as the

side magnets

31, 32 and the air gap or dead spot is disposed between them as shown in FIG. 4. The magnetic fields set up by the

upper strata magnets

61, 62 comprise the upper strata field zone as contrasted to the lower strata field zone of the

side magnets

31, 32 and the

back magnets

45, 46.

Adjacent the back of the stack A of sheets B the

upper strata magnets

61, 62 overlap and are connected to the outer ends of the

cores

33, 34 of the

coils

35, 36 so that the magnets will have the same polarity as the

side magnets

31, 32. Near their opposite ends, these

magnets

61, 62 are connected together by a magnet core 64 of a magnet coil 65 (FIG. 5) connected by

wires

66, 67 to the

generator lead Wires

41, 42. A rheostat 68'is connected into the wire 67 to control the magnetic flux of the coil 65.

With this arrangement of parallel and coextensive lower and

upper strata magnets

31, 32, 61, 62 and holding

magnets

51, 52 of opposing and cooperating polarities as shown in FIGS. 4 and 5 and at ditferent levels, the magnetic fields set up by them tends to distribute the flux pattern completely and evenly over the entire area of the sheets to facilitate an improved separation of the uppermost sheets in the stack and to support the top sheet in suspension over the uppermost sheets.

Although electro-magnets have been described in this specification and shown in the drawings, it should be understood that permanent magnets may be used with equally well results.

In order to facilitate the horizontal feeding of the suspended sheet as shown in FIG. 3, into the feed rollers 25, the

holding magnets

51, 52 are provided with side rollers 71 which extend slightly below the holding magnets and on which the sheet rides in anti-friction fashion as it moves horizontally while still under attraction by the magnets. These anti-friction rollers 71 are carried in support housings 72 which are secured to the inner and outer side faces of the holding magnets at intervals along the length of the magnets. These housings 72 are spaced close together to provide a' substantially continuous sup- 4 port for the suspended sheet as it moves along the

magnets

61, 62 into and through the feed rollers 25.

It is thought that the invention and many of its attendant advantages will be understood from the foregoing description, and it will be apparent that various changes may be made in the form, construction and arrangement of the parts without departing from the spirit and scope of the invention or sacrificing all of its material advantages, the form hereinbefore described being merely a preferred embodiment thereof.

I claim:

1. In a sheet feeding machine, the combination of a magazine for holding a horizontal stack of magnetizable sheets, a plurality of horizontally disposed magnets extending along the opposite sides of the stack of sheets at a level below the line of feed of the topmost sheet to be fed from the stack, said magnets constituting a lower strata magnetic field operable to magnetize the sheets to set up a repelling force thereb'etween to vertically separate the sheets in the upper portion of the stack, a plurality of horizontally disposed magnets supported by said first mentioned magnets and extending along said opposite sides of the stack of sheets at the level of said line of feed and constituting a secondary upper strata magnetic field operable to magnetize said topmost sheet to set up a sheet repelling force therein to prevent feeding of more than a single sheet from the stack, means for engaging and elevating said topmost sheet into between the magnets of said secondary magnetic field to be magnetized thereby, saidfirst mentioned lower strata magnets being cut away at their upper ends to provide a pair of parallel air gaps above the opposite sides of said stack of sheets, said air gaps having a magnetic field of reduced intensity to restrict the vertical level of the topmost sheet of the magnetically separated sheets, said suction means engaging and elevating said topmost sheet through said air gaps into between said secondary magnetic field magnets to be magnetized thereby, and a plurality of horizontally disposed magnets disposed above and extending between and parallel to said first mentioned plurality of magnets for vertically attracting and yieldably holding said topmost sheet out of contact with a subjacent sheet for individual feeding from said magazine.

2. In a sheet feeding machine, the combination of a magazine for holding a horizontal stack of magnetizable sheets, a pair of horizontally disposed magnets of opposite polarity extending along the opposite sides of the stack of sheets at a level below the line of feed of the topmost sheet to be fed from the stack, said magnets constituting a lower strata magnetic field operable to magnetize the sheets to set up a repelling force therebetween to vertically separate the sheets in the upper portion of the stack, a pair of horizontally disposed magnets of opposite polarity supported by and extending along said opposite sides of the stack of sheets at the level of said line of feed and constituting a secondary upper strata magnetic field operable to magnetize said topmost sheet to set up a sheet repelling force therein to prevent feeding of more than a single sheet from the stack, suction means for engaging and elevating said topmost sheet into between the magnets of said secondary magnetic field to be magnetized thereby, said first mentioned lower strata magnets being cut away at their upper ends to provide a pair of parallel air gaps above the opposite sides of said stack of sheets, said air gaps having a magnetic field of reduced intensity to restrict the vertical level of the topmost sheet of the magnetically separated sheets, said suction means engaging and elevating said topmost sheet through said air gaps into between said secondary magnetic field magnets to be magnetized thereby, and a pair of horizontally disposed magnets disposed above and extending between and parallel to said first mentioned pair of magnets for vertically attracting and yieldably holding said elevated topmost sheet out of contact with a subjacent sheet for feeding from said magazine.

games? 3. The sheet feeding machine of claim 2 wherein a plurality of sharp projections extend inwardly from the upper ends of said pair of lower strata magnets over the opposite side edges of the topmost magnetically separated sheet in the stack and into the path of vertical travel thereof, to insure elevation by said suction means of single sheets only from the stack of sheets in said magazine.

4. The sheet feeding machine of claim 2 wherein a plurality of idler rollers are carried by and depend from said pair of holding magnets for engagement with single sheets elevated by the latter to facilitate horizontal feed of said sheet longitudinally of said holding magnets with a minimum of friction.

References Cited in the file of this patent UNITED STATES PATENTS Free Jan. 16, 1923 Moore Oct. 1, 1935 Carter Mar. 12, 1940 Buccicone Apr. 24, 1945 Chatterton June 21, 1949 Maher Mar. 23, 1954 Kimbro Aug. 19, 1958 Gulick Nov. 18, 1958 FOREIGN PATENTS Great Britain Apr. 22, 1953