US2756673A - Sheet controlled interrupter for rotary printing machines - Google Patents

Description

July 31, 1956 H. F. GEORGE 2,756,673

SHEET CONTROLLED INTERRUPTER FOR ROTARY PRINTING MACHINES Filed Aug. 29, 1952 2 Sheets-Sheet 1 y 1956 H. F. GEORGE 2,756,673

SHEET CONTROLLED INTERRUPTER FOR ROTARY PRINTING MACHINES Filed Aug. 29. 1952 2 Sheets-Sheet 2 Ml I .l'Nl/ENTOR 14441 4 m M ATTORNEY SHEET CONTROLLED INTERRUPTER FOR ROTARY PRINTING MACHINES Harvey F. George, Richmond Hill, N. Y., assignor to Davidson Corporation, a corporation of Illinois Application August 29, 1952, Serial No. 307,012

'2 Claims. (Cl. 10'1233) This invention relates to rotary printing machines, and particularly, to machines of this type wherein the printing cylinders are adapted to be separated in the event of a failure to introduce a sheet to the printing couple in a machine cycle.

In rotary printing machines, whether they be of the direct or offset class, ink impressions are transferred to a sheet from a printing surface and against an impression surface in rolling contact. In order that the impression surface will not unnecessarily gather ink from the printing surface and thereby smear or smudge the backs of the printing sheets, provision is usually made in such machines to separate the printing couple to prevent direct contact between the printing and impression surfaces when a sheet is not fed in a printing cycle.

Many difierent solutions, both electrical and mechanical, have heretofore been proposed to achieve this desired result. These devices have usually employed feeler fingers located in the'vicinity of the sheet feeding mechanism to detect the absence of a sheet and trip mechanism to effect the separation of the cylinders.

According to the present invention, the feed rollers which advance the sheets to the printing couple serve as the detecting means, and, in the absence of a sheet, electrically condition latch mechanism for release, which release is subsequently efiected in proper-timed relation in the machine cycle. The use of the feed rollers to detect the absence of a sheet makes possible the elimination of supplementary feeler fingers and the mechanical linkages and operating parts associated with them.

The various novel features and operating parts comprising the present invention will be more fully set forth in the accompanying drawings and the detailed description which follows.

Referring to the drawings:

Fig. l is a side elevation of a printing machine equipped with the present invention.

Fig. 2 is a rear elevation of the upper cylinder illustrat ing its manner of support and certain mechanical parts of the present invention.

Fig. 3 is a circuit diagram of the control system.

The present invention is shown and described in connection with and as applied to a duplicating machine of the type disclosed in U. S. Letters Patent to W. W. Davidson, No. 2,561,015. The machine comprises generally a small cylinder 1 arranged above and in tangential relation with a large cylinder 2, the latter being twice the size of the former. Both cylinders are supported in side frames A of the machine.

The machine is capable of doing both direct and offset printing. When used for direct printing, the large cylinder 2 carries type which prints directly onto sheets passing between the cylinders, the smaller cylinder, in such case, acting as an impression cylinder against which the paper is printed. When used in offset printing, however, the small cylinder acts as a blanket, receiving the ink impressions from a plate segment of the larger cylinder and nited States Patent shaft 14 in a clockwise direction, as seen in Fig. 1, to

2,756,673 Patented July 31, 195.6

printing directly onto a sheet against a platen segment of the large cylinder.

The sheets are fed to the printing couple from a tray or table 3 between guiding side walls 4 onto a main feeding surface 5 where they are presented between upper and lower feed rollers 6, 7, respectively. The upper feed rollers are longitudinally spaced in relation on a driven shaft 8 journaled at opposite ends in a pivotal frame or cradle 9 mounted in the side frames A. The upper rollers 6 are preferably made of rubber or other suitable composition of good friction characteristics, except as hereinafter mentioned, so that when engaged with a sheet they are effective for advancing it.

The lower or idler feed rollers 7 are arranged on a shaft 10, journaled in the side frames A of the machine, and are spaced in the same relation as the upper rollers 6. The supporting surface or table 5 is provided with suitable spaced openings through which the lower rollers project to engage the undersides of the sheets. The idler rollers 7 are preferably made of metal having grooved or knurled sheet engaging surfaces.

The pivotal frame or cradle 9 which supports the upper feed rollers 6 is cam operated to carry the said rollers toward and into feeding relation with the lower rollers for advancing the sheet and then away from the lower rollers topermit the introduction ofa new sheet in feeding position between the upper and lower rollers. The supporting shaft 3 carries thereon, spaced between the upper feed rollers, a number of downwardly vertically disposed stop fingers 11 which are adapted to engage the leading edges of the sheets to properly position them for feeding, even though the upper rollers are in the raised position. When a sheet has been so positioned between the rollers and against the stops, at the proper time in the machine cycle, the upper feed rollers are lowered into frictional contact with the sheet, and the shaft 8 is driven through a partial revolution, which rotation serves both to rotate the stop fingers out of the way and to advance the sheet to the moving grippers (not shown). The grippers close on the leading edge of the sheet and guide it through the printing couple. As soon as the leading edge of the sheet has been advanced to the grippers, the upper feed rollers are again raised to inactive position and the paper stops 11 returned to the downward vertical sheet engaging position.

The machine, as thus far described, forms no part of the present invention, and for a complete understanding of its operation, reference may be had to the above cited patent.

Turning now to the present invention, as stated above, the upper cylinder 1 is mounted in the side frames A for movement toward and away from the large cylinder 2 under certain conditions. The large cylinder, as usual, is supported on a shaft 12 journaled in the side frames A of the machine. The upper cylinder 1, however, is rotatably supported on a pivotal shaft 13, which shaft is supportedin the frames of the machine by eccentric stub shafts 14 at both ends thereof, so that when the shafts 14 are pivoted in a clockwise direction, as viewed in Fig. l, the cylinder 1 will be translated away from the cylinder 2. As usual, the cylinders are gear driven from suitable drive means, and the drive connection is not broken when the cylinders are separated.

The cylinder 1 is normally urged to separated position by a tension spring 18 attached to one of the frames A and acting through a lever 16 and an arm 15. The arm 15 is affixed to one of the eccentric shafts 14, and the lever 16 is loosely mounted on the same shaft adjacent to the arm, and adjustably attached in relation thereto by a slot and locking pin connection, the pin being designated by the reference numeral 17. The spring 18 is attached to the upper end of the lever 16 and tends to rotate the effect the separation of the cylinders, however, a horizontally disposed member 19, having a vertical stop surface 19a, normally engages the lower end of the lever 16 to maintain the cylinders in printing relation. Incidentally, it may be mentioned at this point that, in the preferred design, these contacting surfaces meet on a substantially vertical plane, however, it is obvious that the contacting surfaces may be slightly beveled, in which case they will meet at an angle from the vertical.

The horizontally disposed member 19 is centrally and pivotally supported at the lower end of a vertically disposed bracket 20, which bracket is pivotally attached to the frame A at its upper end to permit a certain amount of horizontal movement to the member 19. The member 19 is acted upon at the right end thereof, as viewed in Fig. 1, by a relatively light spring 21, urging the stop surface 19a in raised position to engage the lower end of the lever 16. The member 19 is further acted upon by a relatively heavy tension spring 22 which overcomes the effect of the spring 18 and not only maintains the upper cylinder 1 in proper printing contact with the lower large cylinder, but also permits a certain amount of give when exceptionally thick sheets are introduced between the cylinders.

From the aforegoing description, it is apparent that when the member 19 is pivoted in a clockwise direction, as viewed in Fig. 1, the stop surface 19a thereof is lowered out of the way of the lever 16, and the spring 18 is free to effect the movement of the cylinder 1 to separated position. In the present preferred embodiment, a solenoid 23, mounted to the inside surface of the frame A, is adapted, when energized, to urge the member 19 to its inoperative releasing position, however, the member 19 is restrained until a predetermined point of time in the machine cycle. Actually, the cylinders can be separated at any time after the printing of the previous sheet and before ink impressions are transferred from the blanket to the platen segment, however, it is believed preferable to effect separation either before or after the ink impressions are transferred from the plates to the blanket, or in other words, when the blanket is in tangential relation to one of the gaps between the plate and platen segments of the large cylinder. In the present embodiment, separation is effected just before the actual printing operation. Accordingly, the left end of the member 19 is connected to the vertically movable armature 23a of the solenoid. To allow some degree of horizontal movement to the member 19, the end portion thereof is slotted to accommodate the armature. The lower end of the armature is provided with a nut or collar 24 to engage the lower surface of the member 19, while a cushioning spring 23b engages the upper surface of the member. When a missing sheet is detected in the feeder mechanism, the solenoid is energized and an upward releasing force is applied to the member 19, however, the frictional resistance between the contacting surfaces of the member 19 and the lever 16 prevents the operation of the solenoid, the opposing actions of the springs 18 and 22 making for a very high frictional resistance.

At a given point of time in the machine cycle, but before printing, the frictional resistance between the contacting surfaces of the member 19 and the lever 16 is broken, and the solenoid is permitted, if energized, to operate the member 19 to release position. For this purpose a lever 25, pivotally mounted to the outside surface of the frame A, is momentarily operated in a clockwise manner, as viewed in Fig. 1, during each cycle of the machine. The operation of the lever 25 is controlled at its lower end by a cam 26 on the shaft 12. The upper end of the lever 25 is provided with a head portion 27 and an adjustable screw 27a. The operative end of the screw 27a is adapted to momentarily engage the free end of an arm 28 (see Fig. 2) attached to the very end of the eccentric shaft 14, outside the frame A, and the slight rotative movement thereby imparted to the lever 16 separates the contacting surfaces and permits the member 19 to be pivoted to inoperative position, if the solenoid has been previously energized. With the stop thus released, the spring 18 is free to effect the separation of the printing couple in the manner above described. Of course, if the solenoid has not been energized, the light spring 21 maintains the member 19 in operative position, preventing separation of the printing couple.

The solenoid 23 is energized to bring about the separation of the printing cylinders during each cycle of the machine that the feed rollers 6, 7 fail to detect a sheet in position for feeding. A circuit is established to the solenoid whenever the upper rollers are lowered into feeding relation with the lower idler rollers and make direct contact with each other instead of an interposed sheet. To permit the establishment of a circuit, one of the centrally located upper feed rollers is covered with a thin metal conducting strip 6a (see Figs. 1 and 3) and the lower metal rollers are grounded. The operating circuit is best described by reference to Fig. 3. A main voltage supply of volts A. C. is imposed on the primary of a transformer T when a main control switch 31 is closed. The metal strip 611 of the upper feed roller is connected to the secondary of the transformer by means of a contact leaf spring 30. When electrical contact is made between the upper and lower feed rollers, a circuit is completed in the secondary of the transformer through a protective fuse 32 and the solenoid 23 to ground.

The closing of the main switch 31 completes a circuit to a pilot light 34 which indicates that the circuit associated with the solenoid 23 is in readiness for operation. To complete the circuit to the drive motor 33 of the machine, it is necessary that a switch 35 in series with the motor also be closed.

If the printing couple has been separated for failure to feed a sheet thereto, as soon as the upper feed rollers are raised in the normal course, the circuit to the solenoid 23 is broken and the pivotal member 19 is left to the return influence of the spring 21. Because the lever 16 is still in its extreme clockwise position, the stop surface 19a is unable, as yet, to re-engage the lever, however, the lever 25 is again actuated before the next succeeding printing operation and, acts not only to rotate the shaft 14 to return the cylinder 1 to printing relation, but to rotate the lever 16 in position to be re-engaged by the stop 19a. Of course, in the event of a failure to feed the succeeding sheet, the operation of the solenoid will prevent the return movement of the member 19 to operative position.

The invention has been shown and described in preferred form only, and by way of example, but obviously many variations and modifications may be made therein and in its mode of application without departing from the spirit of the invention. For example, a more powerful solenoid could be used to effect immediate separation of the printing couple, if desired. It is to be understood, therefore, that the invention is not to be limited to any specific form or embodiment, or in any other respect, except in so far as such limitations are specified in the appended claims.

Having described the invention, the following claims are made:

1. In a printing machine having at least two cylinders between which successive sheets are introduced to receive ink impressions and wherein the cylinders are separated upon the failure of a sheet to be introduced, the combination of an eccentric support for one of said cylinders, a latch means associated therewith, first spring means connected to said latch means and acting thereon to pivot said means in one direction and thereby separate the cylinders, a latching member which engages said latch means, second spring means connected to said latching member and acting thereon to move said member into latching engagement with said latch means wherein said member and said latch means are in frictional contact,

said second spring means being of sufficient strength to cause said latching member to pivot said latch means in a direction opposite to that caused by said first spring means and thereby bring the cylinders into printing relationship, means for detecting when a sheet is not fed to be printed, a solenoid operable responsive to said detecting means for urging said latching member to a nonlatching position, a cam rotatable in timed relation to the rotation of said cylinders, a lever operated by said cam to pivot the latch means first in one direction and then in the other direction, the latter movement being effected by said first spring means, and means for arresting the movement of said latching member due to said second spring means during the lever actuated pivoting of said latch means to momentarily break the frictional contact between said latching member and said latch means whereupon, if a sheet is not fed, the latching member is moved to a non-latching position under the control of the aforesaid solenoid and the first spring means is rendered efiective to separate the cylinders.

6 2. A combination according to claim 1 including additional spring means for moving said latching member back to a latching position when the latch means is subsequently pivoted by the cam controlled lever whereby the cylinders are brought into printing relationship for printing subsequently fed sheets.

References Cited in the file of this patent UNITED STATES PATENTS 1,095,751 Tucker May 5, 1914 1,171,804 Reifsnyder et al Feb. 15, 1916 1,955,814 Kranz Apr. 24, 1934 2,356,058 Hunting Aug. 15, 1944 2,539,382 Davidson Jan. 30, 1951 2,547,470 Janke Apr. 3, 1951 2,594,705 Aberle Apr. 29, 1952 2,651,990 Johnson Sept. 15, 1953

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