US2726865A - Sheet feeding mechanisms - Google Patents

Description

Dec. 13,1955 H. BACKHQUSE 2,726,865

SHEET FEEDING MECHANISMS Filed Aug. 13, 1952 2 Sheets-Sheet l 2 in 9 w Dec. 13, 1955 'c sE 2,726,865

SHEET FEEDING MECHANISMS Filed Aug. 13, 1952 2 Sheets-Sheet 2 United States Patent SHEET FEEDING MECHANISMS Headley Townsend Backhouse, Nassau, Bahamas Application August 13, 1952, Serial No. 304,101 Claims priority, application Great Britain August 22, 1951 8 Claims. (Cl. 2710) The invention relates to sheet feeding mechanisms of the kind which are employed in conjunction with printing and like machines operating on single sheets of paper, card and the like and in which the sheets are fed by conveyor means onto a feed-board where registration of each sheet in turn is effected against front lays, usually also against side lays, and are then taken individually to or by the printing or other machine. be conveyed to the feed board in the form stream of partly overlapping sheets.

A difiiculty which arises with mechanisms of the above kind is that the front edge of the sheet which is approaching the front lays sometimes rises above the lays and passes over the lays without registration and out of the proper time. This ditficulty is especially pronounced when, as is frequently desirable, the registration or partial registration of the front edge of each sheet is effected beneath the rear portion of the preceding sheet during the removal thereof to the printing or other machine. In some constructions of mechanisms of the above kind a preliminary registration of the sheets is effected by means of preliminary lays which move with the sheets after engagement thereby and serve to slow down the sheets before the sheets'reach the front lays as well as to efiect a preliminary registration. The abovementioned difficulty also arises with such preliminary lays.

It has already been proposed in United States Patent No. 2,087,997 to overcome the above difl'iculty by the provision of a cover plate on a registering gauge and of a suction gripper which is positively raised above the level of the feed-board to the maximum height to which a sheet is likely to rise, then grips the sheet and is then given a downward movement to draw the sheet down onto the board and under the cover plate, the gripper also being given a movement along the board such that it travels with the sheet towards the gauge. A disadvantage of this arrangement which the present invention seeks to overcome, is that each sheet which is proceeding normally (i. e. is in the desired position in which it is lying down on the board) is lifted by the gripper as it rises, to the undesired position of an abnormal sheet thereby introducing the risk of causing a sheet which would otherwise have proceeded correctly to pass Over the cover plate should the gripper fail properly to grip the sheet.

According to the present invention there is provided beneath the feed-board in a sheet feeding mechanism of the above kind, a suction gripper which is arranged to be raised above the level of the feed-board by spring or suction means and to be withdrawn to or below the level of the feed-board by suction means operable by the sealing of the mouth of the gripper, whereby the gripper rises only until it engages a sheet, whether the sheet be on the feed-board or raised therefrom, and is then immediately retracted, gripping the sheet and without raising the sheet to any substantial extent.

It is an advantage of the construction according to the of a continuous The sheets may the sheet .26 advanc invention that the retraction of the gripper may be effected very rapidly.

In one form of the invention the suction gripper is carried on the upper end of a tubular piston rod of which the lower end is attached to a piston working in a cylinder closed at both ends and means are providing for admitting suction to both sides of the piston, the arrange ment being such that so long as the gripper mouth is open the suction is prevented from building up in the lower end of the cylinder by intake of air to the lower end through the gripper mouth and piston rod and that the suction in the upper end of the cylinder moves the piston and gripper upwardly until the gripper mouth engages and is sealed by a sheet when the suction builds up in the lower end of the cylinder and, acting upon a larger area of piston due to the absence of the piston rod, overcomes the upward pull of the suction on the upper end and draws the piston and gripper downwardly.

Preferably the gripper is given a movement in the forwarding direction while gripping the sheet, this movement conveniently being obtained by mounting the cylinder and gripper on an arm extending from an oscillatory shaft or by constructing them as such an arm. Further, this movement may also serve to operate a valve control? ling .the admission of suction to the cylinder and gripper. The arm may also carry a preliminary stop or lay.

One specific construction of a sheet feeding mechanism embodying the invention will now be described by way of example of the invention and with reference to the drawings in which:

Figure 1 is a front view of part of the mechanism,

Figure 2 is a section in the direction 22 in Figure 3,

Figure 3 is a view on the line 3-3 in Figure 1, and

Figures 4-8, are sections on the line 44 in Figure '1 showing the parts at various positions in the cycle of operations and showing, in Figure 6, additional par-ts of the mechanism.

In this example there is provided beneath a feed-board 10 an oscillatory shaft 11, the shaft extending transversely of the board near the front edge 12. The shaft is supported by two brackets 13 dependent from the board at positions spaced apart across the board. The arrangement of the two brackets and associated parts is the same and for simplicity only one of the arrangements is shown in the drawings and described.

Each bracket 13 has an internal throughway 14 leading from an attachment for a suction pipe 15 to a port 16 on one side face 17 of the bracket. Adjacent to this side face there is an arm 18 on the shaft '11 which is spring pressed (by spring 19 and collar '20) into contact with the face i7. The arm 18 extends upwardly through a slot 22 in the board 10 and its upper end 23 is substantially level with the surface of the board. A preliminary catch lay or stop 25 extends upwardly from the end of the arm at the rear of the arm considered in relation to ing over the board.

The arm 18 is internally constructed as a double-acting cylinder 28 with its axis radial of the shaft and extending upwardly. Within the cylinder is ,a piston 29 having a tubular piston rod 36 which may extend out from the upper end of the cylinder. The lower end of the piston rod 30 is in open communication with the lower end of the cylinder and the upper end of the rod 30, which is open to atmosphere, constitutes a suction gripper. A spring 32 around the rod 30 lightly urges the piston downwardly. Both ends of the cylinder are in communication through passageways 33, 3d, 35 in the arm with aport 3.6 which registers with the port 16 in the bracket 13 when the arm 18 is vertical (see Figure 5) so ,that both ends of the cylinder are then connected to suction. The ports '36 and 16 move out ofrcgisteras the arm 18 Patented Dec. 13, 1955.

. in the sheet.

moves away from the vertical in the feeding direction (see Figure 3) thus cutting 05 the suction.

An adjustable airinlet valve 40 is provided on the arm" strength of the grip on the sheet and therelease of the sheet after the suction has been .cut off from the cylinder 28. I

Inthe operation of the mechanism the shaft 11 is oscillated to rock the arm 18 from a position at which it is perpendicular to the feed-board (see Figure 5) and in the direction of feed (i. e. anti-clockwise as viewed in Figures 4-8), to a position in which the preliminary lay 25 is lowered beneath the board 10. The timing of the movement, in relation to the advancing sheets, is such that the arm 18 reaches the aforesaid perpendicular position (Figure 5) at the time when the front edge of the sheet 26 has just reached a position to cover the gripper mouth, or shortly after that time, and the reverse movement then begins so that the gripper moves with the sheet toward the main front lays. Just before the arm reaches the perpendicular position (i. e. when as shown in Figure 4) the two suction ports 16, 36 register and suction is applied to both. ends of the cylinder 28. As, at this stage, the lowerend of the cylinder 28 is open to atmosphere through the piston rod 32 and gripper mouth the efiect is to cause the piston 29 and gripper rapidly to move upwards as suction builds up in the upper end of the cylinder 28. This movement continues until the gripper makes contact with the sheet (as shown in Figure 5) whether the latter be resting on the board or raised above it to a small extent as shown. The sealing of the gripper mouth by the sheet and consequently building up of suction in the lower end of the cyIindeI -the suction acting on a larger effective area of the piston than the suction in the upper end of the cylinder-cause the piston 29 and gripper at once to move rapidly downwardly carrying the sheet with them to the position shown in Figure 6 and thereby ensures that the front edge is positioned for engagement with the preliminary lays 25. The arm 18 then rocks to move the gripper with the sheet towards the gripper mouth downwardly at suction gripper having an upwardly directed gripper mouth in front of the lay, impositive means operating in timed relation with the arrival of each sheet above the gripper for raising the gripper mouth to a position above the free-board to engage said sheet, and suction operated means over-ruling the raising means for moving the least .to the level of the surface of the feed-board, said suction operated means being open to the atmosphere through the gripper mouth,

whereby said suction operated means are inoperative where themouth is open and are rendered operative when 7 the mouth is sealed by engagement'with a sheet.

main front lays 37 (see Figures 7 and 8). The movement takes the suction ports 16, 36 out of register so that suction is mouth and the sheet is released. The movement continues until the preliminary lay is lowered beneath the surface of the board. During the initial period when the gripper has hold of the front portion of the sheet and is stationary the rear portion may continue to be driven forward by the conveyor means with the result that a slight buckle is formed This buckle may be employed to urge the front edge forward to the main front lays after the sheet has been released by the gripper. Alternatively the grip of the gripper may, by means of the air valve described above, be adjusted to be such as to permit the sheet to continue its movement by sliding over the gripper. v

' With a view to ensuring that the sheet shall not ride over the front lays after it has been released by the suction gripper there may be provided smoother bars as indicated diagrammatically at 41 in Figures 7 and 8. These bars are lowered to press the. sheet downwardly, after the rear portion of the preceding sheet has been removed and are raised after registration has been effected to permit removal of the sheet, The smoother bars 41 are lowered at a ratesuch that they follow closely the downward movements of the preliminary lays 25.

I claim: 7

l. A sheet feeding mechanism comprising a feed-board, conveyor means for feeding a timed succession of sheets onto the feed-board, a front lay for effecting registration of the front edge of each sheet in turn, the lay being movable to and from a position in which it projects upwardly from the feed-board in the path of the sheets, a

cut off from the cylinder 28 and gripper 2. A sheet feeding mechanism as claimed in claim-1 and including means for imparting to the gripper a movement in the forwarding direction while. the gripper is gripping the sheet.

3. A sheet feeding'mechanism as claimed-in claim 1 and including a valve for controlling the opening of the suction operated means to a source of suction and for releasing suction from said suction operated means and means for operating the valve in timed relation with the feeding of the sheetssuch that the suction operated means are opened to the suction sourceshortly after a sheet is fed over the gripper mouth and suction is released from the suction operated means after the gripper mouth has been moved downwardly as aforesaid.

4. A sheet feeding mechanism comprising a feed-board, conveyor means for feeding a timed succession ofsheets onto the feed-board, a front lay for effecting registration of the front edge of each sheet in movable to and from arposition in which it' projects upwardly from the level of the surface of the feed-board in the path of the sheets, an upright cylinder beneath the level of the surface of the feed-board at. a position in front of the lay,' the cylinder being closed at both ends and havingsuction-inlets to both ends, a piston reciprocable in the cylinder, an upright tubular piston rod passing through the upper end of the cylinder with a suction gripper'mouth. at the upper end and attached to the piston at the lower end with a throughway from the'gripper mouth through the inside of'the rod and the piston to the lower end of the cylinder, the cylinder being so positioned that when the piston is at the upper limit of the travel the gripper mouth is above the level of the sur- 7 that when a sheet is above the gripper mouth both ends,

of the cylinder are opened to the source of suction thereby causing the piston to rise by the action of the suction in the, upper end of the cylinder until the gripper mouth is sealed by engagement with the sheet whereupon the piston is caused to descend by the action of the suction in the lower end of the cylinder on the piston over-ruling the suction in the upper end on account of the area of the upper side of the piston being less than that of the lower side by the area of the piston rod.

5. A sheet feeding mechanism as claimed in claim 4 and including means for imparting to the gripper a moveby the sheet as aforesaid and the sheet gripped thereby.

6. A sheet feeding'mechanis'm as claimed in claim 4 and including an oscillatory shaft eitending transversely to the direction of movement of the'sheet and in which the cylinder constitutes at least part of an arm extending from the shaft whereby the gripper may be givenan' oscillatory movement in the direction of movement of the sheets. i I V i 7. A sheet feeding mechanism as claimed in claim 6 in which the arm also carries a preliminary front lay which is moved by the arm to and from a position in which it projects upwardly from the surface of the feedboard. f

turn, the lay being i 8. A sheet feeding mechanism as claimed in claim 6 in which the valve aforesaid is constituted by a fixed member providing a face and the arm aforesaid which moves, in contact, over the face during oscillation of the shaft, the face and the am having ports which move into and out of register during such oscillation and arranged for connection to the source of suction and the cylinder respectively.

References Cited in the file of this patent UNITED STATES PATENTS

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