US2231339A - Sheet feeding mechanism - Google Patents

Description

Feb. 11, 1941.

F. KRUEGER SHEET FEEDING MECHANISM Filed March 28, 1939 5 Sheets-Sheet 1 N RE INVENTOR FRANK KRUEGER 14W 43. $1 1,.

ATTORNEY.

Feb. 11, 1941. F. KRUEGER 2,231,339

SHEET FEEDING MECHANISM Filed March 28, 1939 5 Sheets-Sheet 2 Fig.2

INVENT OR. FRANK KRUEGER ATTORNEY.

Feb. 11, 1941. F. KRUEGER SHEET FEEDING MECHANISM Filed March 28, 1939 5 Sheets-Sheet 5 INVENTOR. FRANK KRUEGER ATTORNEY.

Feb. 11, 1941. F. KRUEGER SHEET FEEDING MECHANISM Filed March 28, 1939 5 Sheets-Sheet 4 INVENT OR. FR NK K RUEGER ATTORNEY.

Feb. 11, F. KRUEGER SHEET FEEDING MECHANISM Filed March 28, 1939 5 Sheets-Sheet 5 (a 4 l I 1 I l l l l l I I I l l I I I I I1 I INVENTOR. FRANK KR'UEGER J 'ww l3 ATTORNEY;

Patented Feb. 11, 1941 UNITED STATES PATENT OFFICE y 2,231,339 SHEET FEEDING MECHANISM of New York Application March 28,1939, Serial No. 264,521

15 Claims.

The present invention relates to sheet feeding mechanism for delivering sheets of material in predetermined sequence to an operating station where forming or other operations .are performed on the sheet. The invention is more particularly concerned with mechanism for feeding metal sheets from which tin cans and the like are formed.

In prior machines of this type there have been certain disadvantages, the chief of which has been the tendency of the machines to feed double, that is, to supply more than one sheet at a time to the subsequent operating station. The sheets tend to stick together due to small 011 deposits and to vacuum created between the sheets stacked together.

My improved sheet feeding mechanism has been developed with a view to eliminating the disadvantages of earlier machines and to provide at the same time a simplified construction which will be more economical to build and will afford less trouble during operation than has heretofore been practical.

In general, my invention comprises a platform which supports a stack of sheets to be fed and a plurality of continuously rotating sucker mem.. bers to successively lift off the topmost sheet and feed it between a pair of feed-out rolls to transmittal to a succeeding station. To employ the suckers more effectively I continuously rotate them at a varying rate of speed, thus during part of the cycle of rotation the suckers rotate more rapidly than during another part of the cycle, thus creating the slowest rate of rotation at the time a sheet is picked up from the stack. The sucker mechanism also includes a valve timing device, by which certain suckers may be actuated independently of others to 'reversely bend the sheet held and thus separate a second sheet 40 which might have stuck to the first sheet when it was lifted. As the suckers feed the gripped sheet to the feed-out rolls they bend the sheet in a direction normal to the first bending. The spring or resistance of the second sheet to bending separates it from the first sheet and allows it to drop back onto the stack. My invention includes a fluid-operated lift to support the blanks and automatic mechanism to actuate the lift to maintain the top of the stack at the same 60 general level adjacent 'to the suckers.

The chief object of my invention has been to provide a sheet feeding mechanism which is positive in action and which prevents the feeding of more than one sheet at a time. An addi- 55 tional object has been to accomplish the desired (Cl. 27l---27) result by improved and simplified mechanism. and other objects in keeping with the spirit of my invention will become apparent from the following description.

To the accomplishment of the foregoing and 5 related ends, said invention, then, consists of the means hereinafter fully described and particularly pointed out in the claims; the annexed drawings and the following description setting forth in detail certain mechanism embodying lo the invention, such disclosed means constituting, however, but one of various mechanical forms in which the principle of the invention may be used.

In the said annexed drawings: 15

Fig. l is a plan view of my sheet-feeding machine;

Fig. 2 is a rear elevation thereof;

Fig. 3 is a side elevation of the left hand side of the machine seen in Fig. 1 with certain 20 parts broken away to show details of the con struction;

Fig. 4 is a partial side elevation of the right hand side of the machine as shown in Fig. 1;

Fig. 5 is a fragmentary section parallel to the 25 sides showing the operation of the sucker mechamsm;

Fig. 6 is a section through one of the sucker elements;

Fig. 7 shows the action of the suckers in flex- 3 in a gripped sheet; and

Fig. 8 is a plan view of the valve plate controlling the suckers.

Referring now to Figs. 1, 2 and 3, the frame of my machine comprises a pair of sides ill and 8 I 2 bolted as at M to a suitable foundation. The side frames extend across the front of the machine at l5 to provide a generally three-sided framework, which is formed as a single casting. 40

A stack of blanks is carried within the frame and gradually raised to supply the sucker mechanism. The side portions of the casting are each provided with a central vertical web ll, behind each of which lies a fluid cylinder l8, carrying a piston i9. A pair of brackets 20 are mounted above the web I! and form caps for respective cylinders i8. Extending through each of the brackets are upper extensions 22 of respective pistons which cooperate to support a transverse bar 25, from which the stack of blanks is suspended. The crossbar is held in position on the piston rods by nuts 26. Packing between the pistons and the respective cylinders is provided 56 as indicated .at 21 and is held in place by a packin ut 28;

Tfie stack holder comprises a flat skeleton frame 30 hung from two rods 32 and 33 and capped at their ends by nuts 34 and 35. The rods extend through longitudinal openings 36 in the crossbar 25 and through corresponding openings in the frame work 30 to support the same. The area .available for the stack of blanks may be varied by reason of the slots and proper positioning of the rods therein.

The stack holder is automatically repositioned to keep the topmost blanks at a level where they may be conveniently gripped and raised, one at a time, by the suckers. To this end oil is pumped into the cylinders I8 by a pump 49 (Fig. 3) actuated by a cam 31 mounted on and rotatable with the shaft which carries the suckers as hereafter described. The pump 40, mounted in the machine frame behind a removable cover. plate 42, includes the usual cylinder and piston. The piston extends above the cylinder at 43 and pivotally carries a link 44, which in turn is pivoted to an arm 45 of a bell crank 41. The bell crank is pivoted to the frame at 49 and is normally urged in a clockwise direction by the spring 50 secured at to the frame and at 52 to an arm of the bell crank.

The pump 40 is operated by a vertical arm 54 of the bell crank which carries a cam follower 55 at its upper end. The follower rides against the cam 31. In the absence of any controlling mechanism to keep the follower out of contact with the cam there will be one stroke of the pump piston 43 for each rotation of the sucker shaft. The oil moved by the pump is transmitted through piping 51 into-the cylinder l9. As oil is pumped into the cylinders the pistons I9 are raised and act throughthe crossbar 25 and rods 33 to raise the table 30. The pump 49 is actuated once during each revolution of the cam 31- until the stack levelreaches a predetermined height where the top sheet may be conveniently gripped by the suckers. The pump is then rendered inactive and further upward movement of the stack ceases until enough sheets have been withdrawn to require that the stack be again raised.

To control the rise of the table and stack thereon an arm 60 is pivotally mounted at 9| on the machine frame and carries a roller 52 mounted to ride on top of the blank pile; Also carried at the pivot GI and movable with the arm 69 is a second arm 63 which is connected through a rod 64 with the arm 54 of the bell crank 41. The lower end of the arm 63 is slotted in the direction of the rod 64 to permit adjustment of the stroke.

As the supply of blanks in the stack diminishes, the roll 62 drops, rocking the arm 63 and acting through the rod 64 to draw the cam follower 55 into engagement with the cam 31 to operate the pump 40 and raise the pistons l9 and table 30. The pump continues to operate until the blanks are raised to the proper height when the mechanism just described is actuated by the roller 62 to push the cam follower 55 away from the path of the cam 31. Thus the Dumping effect of the cam is diminished or terminated, depending on how far the cam follower is moved, until the stack level again drops below a predetermined point. If the follower is moved completely out of the path of the cam the pump 40 is idle. The pump will function through a .shortened stroke if the follower is in a position between that of Fig. 3 and a position out of the path of the cam. The amount of the stroke is dependent on the stroke imparted to the arm 54.

The suckers which lift the topmost blank from the pile and feed it to the feed-out roll are best shown in Figs. 5, 6 and 7. This mechanism comprises three suckers,.generally indicated at 65, mounted on the shaft 61 which also carries the cam 31 heretofore described. Spaced between the suckers are two rollers against which a blank is drawn and which determines the arc through which the blank is bent.

The sucker shaft is continuously rotated in a' clockwise direction (Fig. 5) and once during each rotation a sheet is lifted from the stack and passed to the feed-out rolls.

The individual suckers are best shown in Fig. 6 and each comprises a hollow barrel which slidingly receives a sucker rod 11 terminating at its inner end in a piston construction 18 packed to prevent' leakage. between the two chambers of the barrel on opposite sides of the piston. The sucker rod isfirmly slidingly supported in a bore 80 formed in an extension of the barrel. Packing 82 is held between the rod and barrel extension by a cap nut 94 to provide an effective seal. The open end of the barrel is provided with a cap 86. An opening 81 in a cap allows a vacuum to be created in the adjacent barrel chamber and in the sucker rod and suction pad. A similar opening 88 in the lower barrel portion allows a vacuum to be created in the chamber adjacent that opening all as hereafter described. The sucker rods are each provided with a longitudinal bore indicated at 89, which communicates at the lower end with a yielding rubber suction pad 90. The pads engage a sheet in the usual manner to lift it from the stack. Valve mechanism is employed in cooperation with the suckers to control their operation as hereafter set out.

This mechanism comprisesafixedvalveplate 95 carried axially of the shaft 61 and forming part of the machine frame (Fig. 7). A second valve plate 91 is rotatably carried on the shaft 61 and is spring urged against the plate 95 by acompression spring 99. The free end of the{ spring is held in place bya collar I 99 on the shaft 61. The adjacent faces of the plates 95 and 91 are carefully .flnished to prevent leakage as the latter rotates and wipes over the former. v To control the suckers the valve plate 95 is provided with passages as shown in Fig. 8, which communicate with openings in the valve plate 91. The openings in the plate 91 are four in number and correspond in position to each of the four radii at which the passages in the plate 95 are located.

The four series of openings in the plate 95 lie at four different radii, designated respectively A, B, C and D. The valve passages at radius A communicate with the opening 88 of the middle sucker. The passages at the radius B connect with the top of the same sucker. at radius C connect-with the top of the two outside suckers while the openings at radius D' connect with the bottom portions of the two outside suckers. The valve plate 91 rotates in such a direction that the various openings in the plate 95 are exposed successively in a counter clockwise direction, when, viewed as in Fig. 8.

A sheet is gripped when the suckers have rotated to approximately the solid line position of Fig, 5. Here, the position of the valve mecha- The passages nism is such that the various valve openings are in registration to free all the suckers and allow them to drop down to the dotted line vertical position where they engage the topmost sheet in the stack In the usual manner. This is accomplished by creating a vacuum through the openings 88 and adjacent parts of the respective barrels. Immediately thereafter the vacuum at 88 is broken and a vacuum'is created above the pistons of the suckers to grip the sheet by the pads 90 forming a seal therewith and to thereafter pull the topmost sheet up to the position indicated at S in Fig. 5. As the shaft 61 continues its rotation the central vacuum cup,

cycle.

having been raised with the others is lowered with respect to the two outer suckers which in the meantime maintain their'position. This is accomplished by breaking the vacuum at 81 and creating a vacuum at 88. This action occurs before the suckers have progressed the sheet appreciably beyond the position at S in Fig. 5 and serves to reversely bend the, sheet as shown by the dotted lines of Fig. '1. If two sheets have been stuck together and picked up by the suckers, this deflecting separates the lower sheet and allows it to fall back on the stack and retains only the topmost sheet in position on the sucker.

.The suckers travel at an increasing speed after a sheet is picked up and as rotation continues, the sheet occupies the position S2 with the outer edge wiping over a guide hereafter described, and from this position passes on to the position S3 where it is gripped by the feed-out rolls. As the sheet is gripped by the rolls the valve mechanism acts to release the three suckers from the upper portions of the respective barrels and the vacuum holding the pads to the sheet is broken allowing the suckers and sheet to separate. The suckers then rotate at a more rapid rate until ready to again engage a sheet when their rate of travel decreases.

The suckers and shaft are rotated at a speed which varies for different parts of the rotative While this motion may be attained by a Geneva mechanism or the like, I prefer to employ a pair of elliptical gears, one of which, indicated at IOI, is carried by the sucker shaft and the other I02 of which is carried by an intermediate shaft I03. This latter shaft also carries a sprocket wheel I04 which receives a driving chain I05 driven from a second sprocket wheel on the shaft I00 of a driving motor.

Due to the elliptical gear drive, the rate of rotation of the suckers is varied to provide a relatively long time interval in the region where the suckers are active to pick up a blank and feed it to the feed-out rolls. After the blank has been fed the suckers are moved at an increased rate of speed through the balance of the stroke until they again approach the reg on in which they pick up the next sheet. By this mechanism it is possible to feed a blank at a rate of speed which increases during the interval of time between lifting the sheet from the stack and the time it is gripped by the feed-out rolls. Thus, while the mechanism functions to pick up a sheet at a speed low enough to insure gripping, the rate of movement is immediately accelerated to pass the sheet from the machine in the shortest practical interval. The increased rate of travel over the remaining part of the cycle further increases the feeding rate of the machine.

After a blank has been lifted from the stack by the suckers it is'fed between a pair of feedout rolls and by them fed to a succeeding part of the can equipment. The feed-out rolls comprise a roll I01 mounted in a supporting bracket I 09 and engaged by two rollers III carried as shown in Fig. 3 and urged against the roll I 01 by springs I I2 which may be adjusted in pres-' to a position adjacent the feed-out rolls and is bolted at I21 to a bracket I29. The guide, together with its supporting bracket, may be ad- Justed toward and away from the suckers by reason of the slots I28 and the bolts I30 passing therethrough into the frame.

To facilitate removing the successive top sheets from the stack, a pair of rolls I32 carried at I34 in arms I35 are normally spring urged against the edge of the stack. The arm I35 is pivoted at I31 (Fig. 3). A rod I38 pivoted to the arm I35 at I40 extends through the frame and adjusts the position of the rollers I32 with respect to the stack. The rollers are resiliently urged against the stack by a compression spring I42 interposed between the two ends of the rod I38.

The mechanism just described aids the suckers in feeding a blank. The rollers I32 help to separate and lift the adjacent edge of the top blank from the stack and the arcuate guide I25 functions to properly direct this edge upwardly as the sheet is lifted from the stack to the feedout rolls and to guide this edge between the rolls.

Other modes of applying the principle of my invention may be employed instead of the one explained, change being made as regards the product and method herein disclosed, provided the step or steps stated by any of the following claims or the equivalent of such stated step or steps be employed.

I therefore particularly point out and distinctly claim as my invention:

1. In sheet feeding mechanism, a support for a stack of sheets to be fed from the mechanism one at a time, a plurality of members to grip a sheet from said stack and means operative after a sheet is gripped to bend said sheet to bow the same outwardly on both sides of the normal sheet plane.

2. In sheet feeding mechanism, a support for a stack of sheets to be fed from the mechanism one at a time, a plurality of members to grip and remove a sheet from said stack and means operative after a sheet is gripped to bend the sheet in two directions to separate any second sheet which tends to adhere thereto.

3. In sheet feeding mechanism, a support for a stack of sheets to be fed, a plurality of suckers adapted to remove a sheet from said stack, means to move said suckers in synchronism to remove a sheet and means to extend and retract a sucker out of synchronism with another sucker to bend a sheet to effect a separation of the sheet and any second sheet which tends to adhere thereto.

4. In a sheet feeding mechanism, a support for a stack of sheets to be fed, a gripping member adapted to remove a sheet from said stack, and means to move said gripper at an increasing rate of speed from the time a sheet is gripped until the sheet is released by said gripping member, said means acting thereafter to further increase the rate of speed of said gripping memsaid members to grip a sheet and drive mechanism interposed between said means and said grippers to increase the rate of speed of said gripping member from the time a sheet is gripped until the sheet is released by said gripping member and to thereafter further increase the rate of speed of said gripping member to return it to position to pick up the next sheet.

6. In sheet feeding mechanism, a support for a stack of sheets to be fed, a sucker rotatably carried at one end of said stack to grip the outer sheet adjacent thereto and feed it from said mechanism, means to rotate said sucker at varying rates of speed to impart a relatively slow motion thereto during the interval in which a sheet is picked up and to thereafter increase the rate of rotation during the interval when the sucker is out of engagement with a sheet and returning to a position to pick up the next sheet.

7. In a sheet feeding mechanism, a support for a stack of sheets to be fed, a plurality of suckers rotatably carried beyond one end of the stack, means to rotate said suckers, means to energize said suckers to remove a sheet from said stack during sucker rotation, means -to apply a reciprocating'movement to one of said suckers after a sheet has been removed to flex the sheet and remove any second sheet which tends to adhere thereto.

8. The method of feeding a sheet from a stack to an operating station comprising the step of reversely flexing the central portion of the sheet to separate any second sheet adhering thereto.

9. In sheet feeding mechanism, a support for a stack of sheets to be fed, a plurality of suckers adapted to remove a sheet from said stack, said suckers arranged in a row transversely to the direction of feed of the sheet, and means operative after a sheet has been gripped by said suckers to reciprocate one of said suckers to thereby reversely bend the sheet and separate from said sheet any second sheet which tends to adhere thereto.

10. In sheet feeding mechanism, a support for a stack of sheets to be fed, a plurality of suckers adapted to remove a sheet from said stack, said suckers arranged in a row transverse to the direction of feed of the sheet, and means operative after the sheet has been gripped by said suckers, and while the outer suckers maintaining the outer portions of the sheet in a fixed planeto reciprocate the middle sucker to thereby flex the middle portion. of the sheet in opposite directions so as to separate from said sheet any second sheet which tends to adhere thereto.

11. In sheet feeding mechanism, a support for a stack of sheets to be fed, three suckers adapted to remove a sheet from said stack, said suckers arranged in a row transverse to the direction of feed of the sheet, and means for moving the middle sucker in a line coincident with its axis to thereby flex the mid-portion of the sheet and separate therefrom any second sheet which tends to adhere thereto.

12. In sheet feeding mechanism, a support for a stack of sheets to be fed, gripping means for removing said sheets, one at a time, from said stack, and means for moving said gripping means at an increasing rate of speed from the time a sheet is gripped until it is released by said gripping means.

13. In sheet feeding mechanism, a support for a stack of sheets to be fed, gripping means effective to remove said sheets, one at a time, from said stack, and means for moving said gripping means at an increasing rate of speed from the time a sheet is gripped until it is released by said gripping means, said moving means being efi'ective also to further increase the rate of speed of said gripping means from the time the sheet is released until the gripping means returns to its initial position.

14. Ina sheet feeding mechanism, a support for a stack of sheets to be fed, suction'means for feeding said sheets disposed above said stack and revoluble about an axis transverse to the direction of feed of the sheet, a pair of feed-out rolls having axes parallel with said first-named axis, and a curved guide independent of said rolls and extending from substantially the front edge of said stack to a point adjacent the bite between said feed-out rolls, said guide adapted to direct the front edge of the sheet in the movement of the sheet from the stack to the feed-out rolls.

15. In a method of feeding sheets from a stack to an operating station, the steps which consist in maintaining the outer portions in a relatively fixed common plane while flexing the central portion of the sheet above and below said fixed plane. Y

FRANK KRUEGER.

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