US3125950A - Apparatus for printing successive sheets - Google Patents

Description

M r h 1964 J. 5. AYERS APPARATUS FOR PRINTING SUCCESSIVE SHEETS AT PRE-SELECTED POSITIONS Filed Aug. 21, 1961 2 Sheets-Sheet 1 INVEN TOR. JOHN S. AYERS.

ATTOR N EYS.

March 24, 1964 J. s. AYERS 3,125,950

APPARATUS FOR PRINTING SUCCESSIVE SHEETS AT PRE-SELECTED POSITIONS 2 Sheets-Sheet 2 Filed Aug. 21, 1961 INVENTOR. JOHN S. AYERS.

BY I 0 6 ATTORNEYS.

United States Patent This invention relates to marking or printing, and is for a marking or printing machine which will place a mark on successive independent sheets or work pieces in a pre-selected location.

In many circumstances, particularly in industry, it is desirable to place a mark or indicia of some character on a succession of objects, as for example individual sheets of metal, and to place the mark uniformly on each 7 piece, as for example a definite distance from one end. This is commonly referred to as spo printing.

The present invention is for a spot printing machine which will imprint the desired mark on each successive work piece only once, and in a predetermined location, and has for its principal objects to provide a spot printer of unique construction which is simple to operate, which may be adjusted to suit the size of the work piece, and which is selective as to the location of the printing, and which will operate at high speed.

The machine will hereinafter be specifically referred to in connection with printing on successive sheets of metal, but this is merely by way of illustration, as it is applicable to printing on sheets or strips of any kind, such as paper, composition board, lumber, plywood or the like.

Apparatus embodying the invention comprises a printing roll or cylinder and a conveyor for moving the work piece under the printing roll. The printing roll is driven from the conveyor, so as to operate in isochronism to the movement of a sheet being carried by the conveyor. This drive includes a continuously-driven member, a brake on the printing drum to hold it against rotation, and a clutch for engaging the printing roll with the continuously-driven member at a predetermined time, at which time the brake is momentarily released. The operation of the clutch and brake is controlled through a counter or measuring unit which is set into operation when the leading edge of the work piece moves past a sensing device such as a photo-electric cell and breaks a light beam to the cell. Counting or measuring is effected by an impulse generator which is located between the sensing head and the printing cylinder in the form of a disk, for example, which is driven by the conveyor, and which has a plurality of regularly-spaced apertures therethrough, the distance between the apertures, center-tocenter, corresponding to a predetermined increment of travel of the conveyor, or object mounted thereon. A A light source is located on one side of the disk and a photoelectric cell on the other, so that as each aperture in turn moves between the light source and the photoelectric cell, an electrical impulse is generated. The succession of impulses is registered on the counter as soon as the operation of the counter has been started by the first sensing unit. The counter is set to a pre-selected number, say fifty, so that when the strip, after starting the counter, has moved or been moved by the conveyor a distance sufficient to rotate the disk to generate fifty impulses, the counter will energize a circuit to operate the clutch and release the brake to cause the printing roll to revolve once. After one revolution the clutch disengages, the brake sets, and the counter stops until the trailing edge of the work piece clears the light path between the light source andfirst photo-cell and readies the counter for the next cycle.

3,125,95b Patented Mar. 24, 1964 My invention and the objects and advantages thereof may be more fully understood by reference to the accompanying drawings in which:

FIG. 1 is a schematic illustration of the apparatus and circuit diagram therefor;

FIG. 2 is a fragmentary schematic section in the approximate plane of line II-II of FIG. 1; and

FIG. 3 is an illustrative circuit diagram showing certain functions of the electrical equipment.

In the drawings, 2 designates generally an endless conveyor, 3 designates the receiving end of the conveyor, and 4 is the discharge end. A designates a work piece such as a sheet of metal being entered onto the receiving end of the conveyor. The conveyor 2, as shown in FIG. 2, may comprise two parallel chains designated 2a and 2b attached to the inner face of the supporting pads or flexible strips 2c on which the work piece is actually carried. The two conveyor strips or belts thus formed are separated by an intervening space.

A printing roll or cylinder 5 is supported over the conveyor, this roll being journaled in parallel supporting arms 6, one at each end of the printing roll, these arms 6 being pivoted about a shaft 7 supported at a fixed ele vation above the conveyor. An adjusting screw 8 with a hand wheel 9 threaded through a fixed support 10 serves to adjust the printing roll vertically. A raised printing surface is indicated on the periphery of the printing roll 5a. For clarity of illustration the inking fountain and inking rolls for applying ink to the type which are supported adjacent the printing roll have not been shown, but these are of conventional construction well known to those skilled in the art, and form no part, per se, of the present invention.

As shown in FIGS. 1 and 2 there is a transverse shaft 11 having a sprocket wheel 12 thereon positioned to engage the chain 2a under the top reach of the conveyor 2 so that the shaft 11 will be driven with the conveyor. The shaft 11 in turn carries a sprocket 13 fixed thereon about which passes a chain 14 which passes over a second sprocket 15 on the shaft 7 for rotating the shaft 7 at a speed co-related to the speed of the conveyor. The shaft 7 has a second sprocket wheel 16 therein about which passes a chain 17, and this chain passes around a sprocket Wheel 18 on a shaft 19 projecting from one end of the printing roll, the sprocket 18, however, being loose on the shaft and forming part of a clutch schematically illustrated at 20. There is a cooperating clutch member and brake 21, the clutch and brake assembly comprising the parts schematically illustrated at 18, 20 and 21. This assembly is a commercially available piece of equipment. In one usable form of apparatus of this kind, the brake is applied by spring pressure and is released by an electromagnet, and the clutch is disengaged by spring pressure and engaged by an electromagnet, so that under normal conditions the brake is set and the clutch runs free, but when the electromagnets are energized the brake is released and the clutch is engaged so that the rotation of the sprocket 18 is then transmitted to the shaft 19.

The invention here contemplates an operation wherein, when the strip or plate A moves a predetermined distance under the printing roll 5, the printing roll will rotate a single revolution, making a single imprint at a predetermined spot or location on the strip A, and after one rotation the printing roll will stop and will not again operate until a following work piece causes it to move through the same cycle. The electrical circuits and parts are designed to accomplish this mode of operation.

Near the receiving end of the conveyor there is located a light source such as an electric lamp 22 which projects a beam of light between the two belts of the conveyor to a photo-electric cell 23 positioned below the upper reach of the conveyor. When the leading edge of the work piece A passes under the light source 22, it breaks the beam of light to the photo-electric cell 23 and starts an electronic counter 24 into operation. 23a indicates a multi-conductor cable extending between the photo-electric cell unit and the electronic counter. The electronic counter is a commercial piece of apparatus forming no part of this invention. The one that 1 have found to be satisfactory is sold commercially by Electronic Products Division of Post Machinery Company of Beverly, Massachusetts, and designated Model P-3 and is shown and described in the published circulars of this company.

On the shaft 7 there is a disk 25 having a series of regularly-spaced apertures therein, the distance between centers of the apertures corresponding to a predetermined distance of travel of the conveyor. For example, each inch of travel of the conveyor may rotate the shaft 7 the distance between centers from one aperture to another. These apertures, whatever distance they represent, are at regular intervals around the disk 25, and of course the disk is rotated continuously as long as the conveyor is operating.

There is a second light source 26 positioned to project a beam of light against the apertured surface of the disk 25, and there is a second photoelectric cell unit 27 on the opposite side of this disk so that as the disk 25 rotates, light is alternately passed through the disk 25 from the light source 26 to the photo-electric cell 27. This serves to generate a succession of impulses which are transmitted to the counter 24 and are registered by the counter. 28 designates a multiple conductor cable between the counter unit 24 and the photo-electric head unit 26-27, and 28a merely represents schematically a standard part of the photo-cell circuit.

The internal construction of the counter is such that when the leading edge of the work piece A breaks the light path between 22 and 23, the operation of the counter will be initiated and impulses generated by the rotation of the disk 25 will be counted. There is a selector knob 24a on the counter that may be adjusted for any predetermined number of impulses. When this number of impulses has been counted, the counter will energize momentarily the coil 29 of a latching relay 30, 31 indicating a connection between the output of the counter and the coil 29. Wires 32 and 33 are connected to a source of current supply not shown.

The latching relay has an armature 34 which is moved upwardly and latched when the coil 29' is energized. This serves to close a circuit from supply line 35 through wire 36, relay contact 37, relay contact 38, wire 39, random printing switch wire 41, a clutch and brake unit 21, and wire 42 to the other side of the cur rent supply line designated 43. The energizing of the electro-magnetic clutch and brake releases the brake and engages the clutch to start the printing roll into rotation.

On the end of the shaft for the printing roll 5 there is a cam having a single low point at 45. There is a limit switch 46 having a follower that engages the periphery of the cam 44, and this switch is normally held open by the cam. However, when the low point of the cam comes beneath the follower of the limit switch, the follower drops into the low point of the cam, closing the limit switch. This closes a circuit from power line 32 through Wire 47, the limit switch, and wire 48 and wire 49 to the winding 50 of a time-delay relay 51. The energizing of the time-delay relay closes a circuit from wire 48 through the contacts of the relay 51 and Wire 52 to coil 53 of the latching relay 30 to the return side of the circuit. This releases latching relay and opens the contacts through the latching relay to break the circuit to the magnetic clutch and brake, thereby causing the clutch to release and the brake to be applied, stopping the printing roll or cylinder after one rotation. The time lag from the closing of the limit switch to the application of the brake is just sufiicient to allow the cam 44 to rotate far enough to lift the 4 limit switch follower out of the low point of the cam and open the limit switch.

The printing roll or selector 5 is adjusted to a vertical height above the conveyor where it will normally be clear of the work piece. The printing type 5a, however, projects from the periphery of the cylinder and the adjustment of the cylinder vertically is such that when the work piece passes under the cylinder and the cylinder rotates, the type will be brought against the surface of the Work piece and make printing contact therewith.

The built-in characteristics of the counter are such that after the selected count has been reached and the coil of latching relay "29' has been energized, the counter will reset itself to zero and will not respond to any more impulses from the photo-electric cell unit 2627 until the trailing edge of the work piece which has been printed upon has cleared the light path between light source 22 and photo-cell 23 to reset the counter for the next cycle of operation.

As stated before, the counter is purchased as a standard piece of equipment, and preferably, it functions through the use of electronic tubes and gas tube relays, but for purposes of illustration I have in FIG. 3 shown a simplified diagram to illustrate the performance of these functions by conventional relay circuits. Referring to FIG. 3, when the light path from the light source 22 to the photoelectric cell 23 is interrupted, the coil of an electromagnetic relay 55 is de-energized and a spring moves the armature 56 from the position shown in FIG. 3 to a position where it engages contact 57, establishing a circuit from contact 57 and wire 58 to the armature of a relay 59 which, at that time, is closed against contact 6t, this contact being connected through wire 61 to the counter. The closing of this circuit initiates the operation of the counter in the conventional manner, and it will then immediately record impulses generated by the photo-electric head 2627. When the counter has counted a predetermined number of impulses so as to energize line 31 leading to latching relay coil 29, the electro-magnet 62 of the relay 59 will be energized, moving the armature 59 of said relay out of contact with contact point 69, and making contact with point 63. This deactivates the counter so that it no longer responds to impulses from the sensing 'head 26-27, and resets the counter. When the trailing edge of the work piece clears the light path between the source 22 and photo-electric cell 23, the relay magnet 55 will be again energized, bringing the armature 5d of the relay into engagement with contact 64 which is connected through wire 65 to the electro-magnet 66 of relay 59 to energize said magnet. This moves the armature 59 against the contact 60 and the circuit remains in that condition until the leading edge of a succeeding work piece again breaks the light path between 22 and 23, whereupon the cycle is repeated.

As above indicated, and as will be well understood by those skilled in the art, these functions of activating and deactivating the counter can be accomplished by tube circuits and mechanism inside the counter itself, and the function of which is equivalent for the more conventional forms of apparatus herein described.

With this apparatus it may be assumed, for example, that pieces of sheet metal are to be marked, that the piece is, for example, 12 feet long, and that the mark is to be placed 36 inches back from the leading edge of each sheet. The control knob 24:: of the counter 24, which is calibrated to take into consideration the distance from the photo-electric sensing head 2223 to the printing roll, is set to the required position, and when it has been so set and the machine is put into operation, the printing roll or cylinder will be rotated at the proper time through one revolution to make a single imprint on the sheet at the selected point back from the leading edge, and no other marking will be put on the sheet, even though the shaft 7 with the apertured disk 25 continues to rotate.

Sometimes it may be desirable to use same machine for repeatedly printing on the same sheet, this being sometimes referred to as random printing. This is done, for example, with long strips or webs where the marking is to be repeated at regular intervals. To this end there is provided in the circuit the manuallyoperable random marking switch 4% which is connected across the lines 36 and 39, being shunted across the latching relay, so that if this switch is turned to the random printing position, current then flows from line 35 through the random printing switch 4%, line 41, the magnetic clutch and brake unit, and line 42 to return supply line 43 so that the clutch and magnetic brake then remain continuously energized to hold the brake in a released position and the clutch in an engaged \position. The printing cylinder then rotates continuously and the counter, the latching relays, the photoelectric sensing heads, and the limit switch are all temporarily idled.

if the switch 4% has been set on the random marking and is then to be returned to selective marking, or spot" marking, the current to supply lines 35 and 43 should be cut oil by opening a switch (not shown). Then the printing cylinder is turned by hand until the printing surface 5a is in the normal rest position. Then the switch 4%) is turned to the spot printing position where the shunt circuit around the latching switch is opened. When this has been done, power may be switched into the lines 35 and 43 and the machine will be set to properly spot mark the first work piece that subsequently comes through the apparatus.

In FIG. 1 the driving means for the conveyor is schematically indicated as comprising a motor and gear reduction unit 7%, driving sprocket '71, and drive chain 72 that passes around a sprocket wheel 73 on the pulley shaft at the discharge end of the conveyor. Since the speed of the conveyor, of the impulse generator, and the drive for the drum are all integrated or correlated, the location of the printing on each succeeding piece must for all practical purposes be properly spotted.

While I have shown and described a particular embodiment of my invention, it will be understood that it may be constructed in various ways, and may be used for offset printing or direct printing, or even die stamping where stamping dies are carried on the printing cylinder instead of printing dies, and various other changes and modifications may be made within the contemplation of my invention and under the scope of the following claims.

Iclaim:

1. Spot printing apparatus comprising a conveyor, a printing cylinder positioned over the conveyor, means for driving the printing cylinder and conveyor in unison comprising a drive connection with an electromagnetic clutch and brake unit therein for holding the cylinder against rotation when the clutch is disengaged and releasing the brake when the clutch is engaged, a later.- ing relay having an armature movable to a first position to energize the clutch to engage the same and release the brake and to a second position for de-energizing the clutch to disengage it and setting the brake, an impulse counter connected with the latching relay to move the armature to the first position at a predetermined setting of the counter, an impulse generator operated by the conveyor for generating impulses at regular intervals corresponding to definite increments of conveyor travel, sensing means operated by the movement of the leading edge of a work piece on the conveyor in advance of the printing cylinder for initiating the counting of impulses, means driven by the printing cylinder for moving the latching relay to the second position after one revolution of the cylinder, and means for de-cnergizing the counter after the latching relay 62% has been moved to the first position until the leading edge of a suceceeding sheet passes the sensing head.

2. Spot printing apparatus of the class described comprising a conveyor for moving sheets to be printed upon eneath a printing cylinder, a printing cylinder positioned over the conveyor for printing on sheets being so transported by the conveyor, driving means for the conveyor, means connected with the conveyor for driving the printing cylinder to co-relate the peripheral speed of the printing cylinder to the linear speed of the sheets being transported by the conveyor, a combined electromagnetically-operated clutch and brake mechanism operatively interposed between the printing cylinder and its driving means for holding the cylinder from rotation and holding the clutch disengaged and operative to the clutch and release the brake to cause the cylinder to be rotated, an electric circuit for the electromagnetically-operated clutch and brake mechanism including an electromagnetically-operated switch having two positions, in the first of which it effects the release of the brake and engagement of the clutch to rotate the drum and in the other of which it effects setting of the brake and disengagement of the clutch, means controlled by rotation of the cylinder efiective to move the switch to the second position after a single rotation of the cylinder, and measuring means driven by the conveyor and responsive to any speed variation thereof controlled by the movement of the sheet to be printed upon eliective for moving the switch to the first position, said last-named means comprising a sensing head responsive to the passage of the leading edge of a sheet to be printed upon and a selectively adjustable electronic impulse counter which is energized by the passage of the leading edge of a sheet past the sensing means, an impulse generator driven by the conveyor for generating impulses that are registered by the counter only when it is so energized, said counter being connected with said switch to move it to the first position after a selected number of impulses has been counted, and means for de-energizing the counter when the switch is so moved whereby the printing cylinder is revolved but once for each sheet.

3. Spot printing apparatus as defined in claim 2 wherein there is a selectively movable manually operable switch shunted around said first switch to render said rst switch ineffective when it is desired to rotate the printing cylinder continuously.

4. Spot printing apparatus as defined in claim 2 wherein said sensing unit comprises a photo-electric cell and a light source therefor so disposed along the conveyor that the sheet being carried by the conveyor interrupts the light between the photo-electric cell and its source of illumination before the sheet moves beneath the printing cylinder.

5. Spot printing apparatus as defined in claim 2 wherein said impulse generator comprises a disc having an annular series of regularly spaced light-transmitting apertures therethrough, means for driving said disc from the conveyor, and a light source on one side of the disc and a photo-sensitive cell on the other responsive to light passing from the light source through the suc cessive apertures of the disc as the disc rotates so that the passage of each aperture generates an impulse.

References Cited in the file of this patent UNITED STATES PATENTS 2,251,306 Thompson Aug. 5, 1941 2,324,080 Haunty July 13, 1943 2,615,355 Friedman Oct. 28, 1952 2,617,593 Audier et al. Nov. 11, 1952 2,639,796 Dean May 26, 1953 2,641,998 Donald June 16, 1953 2,743,920 Petre May 1, 1956

Claims (1)

1. 2. SPOT PRINTING APPARATUS OF THE CLASS DESCRIBED COMPRISING A CONVEYOR FOR MOVING SHEETS TO BE PRINTED UPON BENEATH A PRINTING CYLINDER, A PRINTING CYLINDER POSITIONED OVER THE CONVEYOR FOR PRINTING ON SHEETS BEING SO TRANSPORTED BY THE CONVEYOR, DRIVING MEANS FOR THE CONVEYOR, MEANS CONNECTED WITH THE CONVEYOR FOR DRIVING THE PRINTING CYLINDER TO CO-RELATE THE PERIPHERAL SPEED OF THE PRINTING CYLINDER TO THE LINEAR SPEED OF THE SHEETS BEING TRANSPORTED BY THE CONVEYOR, A COMBINED ELECTROMAGNETICALLY-OPERATED CLUTCH AND BRAKE MECHANISM OPERATIVELY INTERPOSED BETWEEN THE PRINTING CYLINDER AND ITS DRIVING MEANS FOR HOLDING THE CYLINDER FROM ROTATION AND HOLDING THE CLUTCH DISENGAGED AND OPERATIVE TO ENGAGE THE CLUTCH AND RELEASE THE BRAKE TO CAUSE THE CYLINDER TO BE ROTATED, AN ELECTRIC CIRCUIT FOR THE ELECTROMAGNETICALLY-OPERATED CLUTCH AND BRAKE MECHANISM INCLUDING AN ELECTROMAGNETICALLY-OPERATED SWITCH HAVING TWO POSITIONS, IN THE FIRST OF WHICH IT EFFECTS THE RELEASE OF THE BRAKE AND ENGAGEMENT OF THE CLUTCH TO ROTATE THE DRUM AND IN THE OTHER OF WHICH IT EFFECTS SETTING OF THE BRAKE AND DISENGAGEMENT OF THE CLUTCH, MEANS CONTROLLED BY ROTATION OF THE CYLINDER EFFECTIVE TO MOVE THE SWITCH TO THE SECOND POSITION AFTER A SINGLE ROTATION OF THE CYLINDER, AND MEASURING MEANS DRIVEN BY THE CONVEYOR AND RESPONSIVE TO ANY SPEED VARIATION THEREOF CONTROLLED BY THE MOVEMENT OF THE SHEET TO BE PRINTED UPON EFFECTIVE FOR MOVING THE SWITCH TO THE FIRST POSITION, SAID LAST-NAMED MEANS COMPRISING A SENSING HEAD RESPONSIVE TO THE PASSAGE OF THE LEADING EDGE OF A SHEET TO BE PRINTED UPON AND A SELECTIVELY ADJUSTABLE ELECTRONIC IMPULSE COUNTER WHICH IS ENERGIZED BY THE PASSAGE OF THE LEADING EDGE OF A SHEET PAST THE SENSING MEANS, AN IMPULSE GENERATOR DRIVEN BY THE CONVEYOR FOR GENERATING IMPULSES THAT ARE REGISTERED BY THE COUNTER ONLY WHEN IT IS SO ENERGIZED, SAID COUNTER BEING CONNECTED WITH SAID SWITCH TO MOVE IT TO THE FIRST POSITION AFTER A SELECTED NUMBER OF IMPULSES HAS BEEN COUNTED, AND MEANS FOR DE-ENERGIZING THE COUNTER WHEN THE SWITCH IS SO MOVED WHEREBY THE PRINTING CYLINDER IS REVOLVED BUT ONCE FOR EACH SHEET.

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