US2720165A - Sheet gripper ejector for duplicating machines - Google Patents

Description

1955 H. R. GULLIXSON ETAL 2,

SHEET GRIPPER EJECTOR FOR DUPLICATING MACHINES Original Filed Nov. 27, 1946 4 Sheets-Sheet l V INVEN TOR5 N Ham/42624561115072,

fierber'i 115/4075,

Oct 11. 1955 H. R. GULLIXSON ETAL. 2,720,165

SHEET GRIPPER EJECTOR FOR DUPLICATING MACHINES Original Filed Nov. 27, 1946 4 Sheets-Sheet 2 Oct 1955 H. R. GULLIXSON ETAL 2,720,165

SHEET GRIPPER EJECTOR FOR DUPLICATING MACHINES 4 Sheets-Sheet 5 Original Filed Nov. 27, 1946 Oct. 11, 1955 H. R GULLIXSON ETAL 2,720,155

SHEET GRIPPER EJECTOR FOR DUPLICATING MACHINES Original Filed Nov 27, 1946 I 4 Sheets-Sheet 4:

INVEN Toka Harald/Zfizzllzxaam United States Patent i SHEET GRIPPER EJECTOR FOR DUPLICATING MACHINES Harold R. Gullixson, Greensboro, N. C., and Herbert F. Bruns, Chicago, Ill., assignors to Ditto, Incorporated, Chicago, 111., a corporation of West Virginia Original application November 27, 1946, Serial No. 712,538, new Patent No. 2,660,113, dated November 24, 1953. Divided and this application November 20, 1953, Serial No. 393,382

1 Claim. (Cl. 101-232) The present invention relates to a duplicating machine of the offset, lithographic type. This application is a division of application, Serial No. 712,538, filed November 27, 1946, now Patent No. 2,660,113, issued November 24, 1953.

In the duplicating machine which is the subject of that patent and in which the present invention may be incorporated, there is provided a main cylinder with plate and impression surfaces, together with associated mechanisms or groups of mechanisms which are compactly and accessibly arranged about the. cylinder with all the controls therefor located so as to be accessible from the front of the machine. The machine is fed from the front either automatically or manually, and in order that an operator be constantly advised of the quality of the work being produced, the arrangement is such that the printed surface of the sheet is delivered printed side up at the front of the machine in direct view of the operator. Any adjustments thus observed by the operator to be necessary can readily be made without movingfrom his position at the front of the machine.

One of the primary objects of the invention disclosed in the aforementioned patent is to simplify a duplicating machine of the offset type, to eliminate many of the parts heretofore used in such machines and to improve the efficiency of the apparatus, by the new arrangement of the essential elements.

The invention which is the subject of this present application provides an improved mechanism for gripping and holding the sheets on the cylinder of such a duplicating machine as the printing operation is performed; and for stripping and ejecting the sheets from the main cylinder, after the printing hasbeen performed.

Specific objects are to provide a sheet gripping means which requires a minimum paper area for gripping; means to insure accurate registration on the master cylinder and positive gripping for any size sheet; and coaction between the gripper and ejector means to permit their effective operation by a common actuating means.

Referring now to the accompanying drawings:

Figure 1 is a side elevation and partial section, taken just inside of the side plate or frame shown in Figure 1;

Figure 2 is a fragmentary plan view of the leading edge of the impression segment of the main cylinder, showing the paperclamping mechanism in closed position;

Figure 3 is an enlarged radial sectional view through the leading edge of the impression segment, showing the paper gripper and ejector mechanism; and

Figures 4, 5, 6, 7 and 8 are diagrammatic views, showing successive steps in the handling of a sheet of paper, from the top of the stack, through the machine until discharge into the receptacle for the printed sheets.

The various sets of instrumentalities making up the duplicating machine of the present invention are supported by a pair of upright side plates such as 2, secured in spaced relation by a plurality of tie rods, including those indicated at 3, 4, 5, and 6. Between the side plates,

2,720,165 Patented Oct. 11, 1955 ICC adjacent the forward end of the machine, there is mounted a vertically movable table 7 for supporting a stack of sheets. At the rear end of the table, there is a fixed guide and air separator 8, adapted to facilitate the delivery of sheets one by one by a sheet feeder, .represented generally at 9. The sheets are picked up individually and advanced rearwardly (to the right in Figure l) by the feeder 9, between the upper and lower feed rolls 10 and 11, against stop fingers 12, and below a detector finger 13.

The main cylinder 14 comprises a plate segment 15, and an impression segment 16 having a sheet gripperejector 17 (Figure 3) associated with its leading edge, which sheet gripper-ejector receives the paper sheet from the feed rolls, clamps the leading edge of the same against the surface of the cylinder and carries it around past the blanket roll for printing.

The plate holding segment 15 of the main cylinder has associated with its leading and trailing ends, plate holding clamps so that the lithographic printing plates may be applied and removed from the cylinder with facility.

Behind the main cylinder, there is journalled a blanket roll 18, having a rubber surface adapted to make rolling contact first with the moistened and inked lithographic plate, for the transfer of an image to the blanket roll, and then to make contact with the paper on the impression segment, to transfer the image to the paper. The blanket roll and the main cylinder are interconnected for rotation in unison by gears 19 and 20 whose pitch diameters are substantially equal to the effective diameters of the blanket roll and the main cylinder, respectively.

Above the main cylinder there is mounted a sheet holddown shaft 21, having a plurality of rotatable disks 22 mounted thereon, overlying the path of movement of the sheet carried by the impression segment of the main cylinder. A sheet stripper 23 is disposed ahead of the hold-down wheels 22, in position to cooperate with the gripper-ejector 17 on the main cylinder, as the latter forces the leading edge of the sheet outwardly. In front of the sheet stripper 23, there is a rotatable shaft 24 having a plurality of disks 25 thereon, serving as a sheet delivery roll, to discharge the printed sheet, face up, into the receiving tray 26, disposed at the front of the machine, and having a sheet hold-down device 27, in the form of a spring finger, associated therewith.

Below the sheet stripper 23 and at the upper, front side of the main cylinder, is a moistening assembly 28.

Below the moistener and above the sheet feeder 9, is an inking mechanism, represented generally at 29.

At the rear of the machine, there is a platform 30 suspended from resilient mounts 31 carried by the side frames 1 and 2, respectively. Supported upon the platform 30 is an electric motor 33 constituting the main drive for. the machine and also connected, through a coupling to a combined air compressor and vacuum pump 34 of conventional design. The pump delivers air under pressure to, and creates suction in various mechanisms in the machine.

At the front of the machine, disposed between the lower ends of the side plates, there is a control panel 35, upon which are mounted all of the control levers, buttons and knobs for all of the different mechanisms in the machine, as will be described hereinafter.

At the rear of the machine, in front of the platform 30 and the motor 33 and compressor and vacuum pump 34, there is a downwardly extending baffle plate 36, supported from the side frames and arranged to prevent the inadvertent delivery of a sheet of paper into the vicinity of the motor and the parts driven thereby, and to guide any mis-fed sheets downwardly to a position below the platform. Above the motor and compressor is a removable plate 37, slidably mounted in guideways formed in brackets 38 carried by the side plates 2 projecting in wardly therefrom. The plate 37 isolates the motor and the compressor from the rest of the machine, but may be removed to give access thereto, whenever desired.

7 From the foregoing description it will be appreciated that the offset lithographic duplicating machine of this invention comprises a machine wherein the feed table 7 and receiving tray 26 are both located in front of the cylinder 14- adjacent the bottom and top thereof respectively while the blanket roll 18 is to the rear of the cylinder 14, and that the blanket roll is rotated in a direction to move a sheet fed by the sheet feeder 9 to the bottom of the cylinder 14 upwardly between the blanket roll and the cylinder, such sheet being delivered to the receiving tray 26 with its surfaces reversed in relation to its positio'n on the feed table 7, the printed surface of the sheet beinguppermost in the receiving tray.

Referring to Figures 48 at the commencement of each cycle of operations, the feed rolls 10 and 11 are separated, the stop fingers 12 are raised and the detector finger 13 is raised. The sheet feeder 9 takes a sheet from the stack"- on table 7 and advances it between the feed rolls, up against the stop fingers. The detector finger is immediately depressed, to feel the paper and to perform the additional function of preventing the sheet from bouncing or sliding back, away from the upwardly projecting stop fingers. The stop fingers are next lowered into the spaces between the rubber rings on the lower feed roll. When the fingers reach their lower limit of movement, the upper feed roll is lowered upon the sheet. and the detector finger is raised. The sheet is rapid- 1y fed forwardly by the feed rolls into the gripper 17 associated with the main cylinder, as explained below. As a result of the use of the detector finger to hold the sheet in position, the relation of the removal of the stop fingers and the dropping of the upper feed roll is not critical, and the stop fingers can be moved well out of the way before the sheet is propelled upwardly between the cylinder 14' andthe blanket roll 18.

The cam 86 controls the raising and lowering movements of the upper feed roll for projecting the sheets into the gripper mechanism 17, which is also carried by the impression segment 16, and which will now be described.

Adjustably secured to the leading end face of the impression segment 16 by suitable bolts are a pair of bearing blocks 191 (Figures 2, 3) in which a rock shaft 192 is mounted. The right hand end of the shaft 192 carries an arm 193, having a cam fol-lowing roller 194 (Figures 4, 5') on its free end, positioned to engage a stationary cam 195, appropriately secured to and projecting inward- 1y fromv a main side plate 2. Adjacent its. ends, the shaft 192 carries laterally projecting arms 197 connected to tension springs 198 having their opposite ends anchored to thecylinder shaft, whereby the shaft is rocked in the clockwise direction, as viewed in Figure 3.

The shaft 192 carries the combined gripper and ejector mechanism 17, which comprises a strip of sheet spring steel cut. and bent to provide a securing surface 200, wrapped around the shaft and attached thereto by rivets or the like, and a plurality of spaced gripper fingers 201 and a plurality of spaced ejector fingers 202.

The ejector fingers 202 are bent downwardly and rearwardly from the inner edges of the central portions of the gripper fingers 201 and are received by milled out recesses 203 formed in the leading end face of the impression segment 16. The gripper fingers 201 are wider than the ejector fingers 202 and seat upon an arcuate surface 204 which extends from end to end of the segment, except wherethe recesses 203 are formed. It should be noted that this surface extends inwardly at an inclination with respect to the circumferential surface 205.

The bottom of the angle between the two sets of fingers 201,202 is disposed away from shaft 192 with the plane of gripper fingers 201 substantially tangentialto the shaft 192. The ejector fingers 202 are longer than the grip-' perfingers 201, and the angle between the two, as shown in Figure 3 is about 35. The bottom of the angle between the two sets of fingers, against which the sheet of paper is fed in the operation of the machine, is eccentric to the swinging axis of the fingers and moves toward the edge of the sheet of paper during the gripping operation and away therefrom during the ejecting operation. The forward movement of the gripping mechanism 17 when opening permits the gripper fingers 201 to release and to move clear of the leading edgeof the sheet of paper, and permits the ejector fingers 202 to function positively in ejecting the sheet of paper. This gripping mechanism may be swung, for example, about 25 for receiving and about 15 more for ejecting a sheet of paper.

Referring to Figures- 48 the gripper is urged to the closed paper clamping position by the springs 198 (Figure 3) and is moved to the open paper" receiving position and to the paper ejecting position by the cam which engages the roller 194, to rock the shaft 192. The cam 195 has afairly pronounced rise 206, to swing the gripperejector to the maximum open position, for raising the leading end of the sheet of paper, above the periphery of the main cylinder, to be engaged by the stripper described below. Until the top of rise 206 is reached, however, theg'ripper fingers secure the blank. Following the rise 2:06 is a dwell 207 which permits the springs 198 to seat the gripper fingers 201 firmly upon the surface 204 of the impression segment, in closed position, as shown in Figure 3 and Figure 6 with the cam following roller 194 free of the cam. In this position, the gripper fingers are located so that they will not make contact with the form rolls of the moistening and inking mechanisms 31 and 32 as the gripper fingers move therepast. Near the lower end section of the cam 195, following the dwell 207;, is a rise 208 which engages the cam following roller 194 and swings the gripper to an intermediate open position, for receiving a sheet of paper. This paper receivirig position, is approximately half-way between the full and broken line positions of the gripper shown in Figure 3. Beyond the rise 208 is a drop 209, which permits the springs 198 to swing the gripper to the closed position, to clamp the sheet firmly upon the surface 204, after it has been fed into the space between the gripper and ejector fingers by the feed rolls described above. Following the drop 209, the roller 194 leaves the cam 195, and the gripper remains in the closed position, under the influence of the springs 198, until the roller again engages the cam rise 206, for sheet ejection.

Thus, it will be seen that the gripper is actuated, after passing rearwardly at the bottom of cylinder travel beyond a vertical plane containing the cylinder axis, to grip the sheet, and after passing forwardly beyond said vertical plane at the top of cylinder travel, is again actuated to eject the sheet.

FiguresA S show a number of successive steps in the feeding of a sheet and in the handling of the sheet from the time it leaves the feed table, through the printing operation, toits. delivery into the receiving tray. Many parts of the apparatus have been omitted in these figures, for the sake of clarity.

Figure 4 shows the relationship at the start of a cycle of operations. Suction feet 371 of the sheet feeder 9 are at their lower position, resting upon the uppermost sheet Sin the stack, having been dropped to this position by the opening of an air valve (not shown). The stop fingers 12 and the sheet detector 13 are raisedand the upper feed roll 10 is in its upper position, spaced above the lower feed roll 14. With the parts in this position, the suction feet will bev lifted, as soon as an air valve is closed and when a sufficient amount of vacuum has been created in the system to lift the feet and the uppermost sheet. Of course, this lifting occurs in a small fraction of asecond. The sheet will then be gripped by a belt 372, as shown in Figure 5. The feed rolls, stop fingers and sheetdetector remain in the same position.

The sheet is now advanced by the forward movement of the belt 372 of the sheet feeder 9, produced by the intermittent motion mechanism, mentioned above, until its forward edge contacts the stop fingers 12. At this time, the suction to the belt 372 will be cut off and the sheet will be released. Simultaneously the detector finger 13 is depressed to hold the sheet on the stop finger plate, as shown in Figure 6.

After a delay of approximately 30 degrees in the rotation of the main cylinder, the stop fingers 12 are lowered. After they have been lowered into the grooves of the lower feed roll, the upper feed roll drops upon the sheet, and the detector finger is raised clear of the sheet. As a result, the sheet is rapidly fed rearwardly and directed into the open sheet gripper 17, as shown in Figure 7. The sheet is guided in this direction, by a roller on the main drive shaft.

The sheet enters the gripper 17 and its leading edge is firmly seated in the V-shaped space between the gripper fingers 201 and the ejector fingers 202, because the speed of movement of the sheet is greater than the peripheral speed of movement of the main cylinder, by approximately 50%. Hence, a buckle is formed in the sheet, as indicated in Figure 8 as the gripper fingers close, to clamp the leading edge of the sheet upon the surface 204 of the impression segment 16.

As soon as the sheet is so gripped, the upper feed roll rises and the sheet is carried around by the gripper, past the blanket roll, as indicated at 8-1 in Figure 4 to receive the printing from the blanket roll.

The air valve is now opened, and the suction feet 371 of the sheet feeder 9 again drop upon the uppermost sheet in the stack.

The stop fingers are again raised into their operative position, ready for the next feeding cycle.

When the cam following roller 194 associated with the sheet gripper engages the rise 206 of cam 195, the leading edge of the printed sheet is pushed outwardly by the ejector fingers 202, as shown in Figure 5 in position to be engaged by the stripper 23. Prior to this time, however, the air valve has been closed and the next sheet has been lifted by the suction feet, for transfer to the belt, as previously described. The first sheet, stripped from the impression segment of the main cylinder by the stripper 23 is propelled forwardly by the ejector wheels 25 and is guided into the receiving tray by the deflector wire 27, mounted thereabove, as shown in Figure 6. Meanwhile, the next sheethas been advanced rearwardly (to the right in Figure 6), with its leading edge against the stop fingers, and the cycle of operations is repeated.

The mechanism here disclosed as functioning in association with the gripper-ejector mechanism is described for the sake of completeness only and is not intended as a limitation on the scope of this invention.

The gripping means itself requires minimum paper area for gripping. The numerous alternating gripper and ejector fingers and the reverse movement of the gripper when closing assure accurate registration and positive gripping for any size sheet. The forward movement of the gripper when opening releases and clears the leading edge of the sheet and permits the ejector to function positively. The unit construction of the gripper and ejector positively relates the action of the two. Obviously, the common actuating means for the gripper-ejector unit is a further simplification.

In the drawings and specification, there have been set forth a preferred embodiment of the invention, and although specific terms are employed, they are used in a generic and descriptive sense only and not for purposes of limitation. Changes in form and in the proportion of parts, as well as the substitution of equivalents are contemplated, as circumstances may suggest or render expedient, without departing from the spirit or scope of this inventionas further defined in the following claim.

It is claimed:

In a duplicating machine, a cylinder having impression and plate surfaces and a gap between the trailing end of the plate surface and the leading end of the impression surface, said leading end being generally radially grooved, a rock shaft mounted at said leading end of the impression surface, a blank gripper and ejector member pivoted along said leading end, said member formed of a strip of sheet spring steel cut and bent to provide securing surface, said securing surface wrapped around and attached to said rock shaft, a plurality of gripper and ejector fingers on said securing surface, said ejector fingers being bent downwardly and rearwardly from the inner edges of said gripper fingers and adapted to be received in said radial grooves, said gripper fingers being wider than said ejector fingers, said ejector fingers being longer than said gripper fingers, said gripper and ejector fingers forming an acute angle eccentric to the axis of said rock shaft for movement toward the blank during gripping operation and away therefrom during ejecting operation, means acting on said member to urge the gripper fingers toward the outer faces of the lands between the grooves to grip the head end of a blank, and cam means acting for timedly rocking said member to cause the gripper fingers to release the blank and the ejector fingers to throw outwardly the head end of the blank.

References Cited in the file of this patent UNITED STATES PATENTS 1,869,403 Belluche Aug. 2, 1932 1,968,849 Morse Aug. 7, 1934 2,154,604 Bradt Apr. 18, 1939 2,358,284 Davidson Sept. 12, 1944

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