GB2182284A - High speed swinging head imprinter - Google Patents

Abstract

A high speed imprinter on frame (1) has a cyclically swingable print head (22), and an ink applicator in the form of a roll (23), and an anvil (24) to drive the work (W) toward and into printing relation to a printing face (38) on the head when the head cycles into a printing position.The inking roll (23) is carried by a heater block (52) which is swingably mounted at (55) and normally biased at (72) in controlled relation toward an inking position (as shown in Figure 4) relative to the swinging cycle of the print head (22). <IMAGE>

Description

SPECIFICATION High speed swinging head imprinter This invention relates to marking devices or imprinters, and is more particularly concerned with a high speed hot ink imprinterwhich is adapted for imprinting marks on momentarily stationary imprintable surface means such as a workpiece in a continuousweborfilm strip form.

Imprinters are extensively used in industry for imprinting indicia on work pieces such as bag making material in strip form, and the like. Forwork pieces that travel continuously, rotary head imprinters have been developed. For work pieces that travel in a stop and go fashion, such as bag making material in connection with bag filling equipment, cartons, or labels in connection with label applicating equipment, imprinters with stamping type print heads utilizing ink ribbon or transfer tape or rotary inking devices have been developed. Printers utilizing stamp pads or ink cartridges have also been developed.

Rotary head imprinters desirably utilize inking rolls impregnated with pig ment or ink that is heat softenable and which will herein be referred to generically as "ink". Type carried by the rotary print head roll contacts the inking roll in each revolution of the print head for inktransfer onto the type faces.

Such inking rolls have the advantage thatthey are usually mounted in a quick-releasefashion forquick replacement or exchange as required and are especially advantageous, as compared to inked ribbon ortransfertape marking, because ofthe ease and speed with which changes can be made for such purposes as ink replenishment, inkcolorchanges, and the like.

As an example, of imprinters ofthe general type with which the present invention is concerned, attention is directed to U.S. Patent 4,528,908 dated July 16, 1985 and which is assigned to the same assignee as the present application. In that patent, is disclosed an arrangement wherein the print head has components of swinging and rectilinear movement in a cycle involving a rectilinear printing stroke and a swinging inking stroke.

Reference is also made to a copending application of the present applicant Serial No. 556,279 filed November30, 1983, and also assigned to the same assignee as the present application. In that disclosure, the print head is activated in printing and inking strokes by elongated swinging lever means.

While it has been found that the imprinters of both of the above-noted disclosures have been improvements over the prior art, there has yet been a demand forsimpler mechanism and higher speed hot ink imprinting.

An important object of the present invention is to provide a new and improved imprinter, in particular ofthe hot inktype, which is simpler, but nevertheless highly efficient and economical in structure, and which operates at a higher rate of speed than comparable prior imprinters.

Another object of the present invention is to provide an improved imprinter having a simplified, high speed rectilinear imprinting mechanism.

Afurther object is to provide improved inking meansforan imprinterofthetypeunder consideration herein.

Still another object of this invention iso take advantage of the normal "duty cycle" of typical packaging machines and labelers, i.e. while the workpiece is travelling, a print head swings up and is re-inked and returns to an imprinting position, and when the workpiece stops momentarily, a short stroke of an anvil-reciprocating actuator brings the workpiece into contact with imprinting type on the print head.

Pu rsuant to the present invention,there is provided an apparatus for imprinting a workpiece having an imprintable surface, comprising: a supporting frame, journal means supported bythe frame on a fixed axis, a print head having one end pivotally supported by the journal means, imprinting means carried by an opposite end of said print head, means for supporting the workpiece in an imprinting position with the imprintable surface facing toward the print head but spaced from the imprinting means, ink applicator means mounted on the frame; means for cyclically swinging the print head from an imprinting position with the imprinting means in imprinting position spaced from the workpiece supporting means, into inking relation ofthe imprinting means to the applicator means, and then return ofthe imprinting meanstotheimprinting position; and means, operable when the print head is in the imprinting position, for driving the workpiece supporting means and thereby the workpiece thereon toward the imprinting meanssothatthe imprintable surface will be pushed by action of the supporting means into imprinting contact with the imprinting means.

Substantial improvement has been effected in the ink applicator means.

On the drawings Other objects, features and advantages ofthe invention will be readily apparent from thefollowing description of a representative em bodimentthereof, taken in conjunction with the accompanying drawings, although variations and modifications may be effected without departing from the spirit and scope ofthe novel concepts embodied in the disclosure, and in which:: Figure lisa front elevational view of a hot ink imprinter embodying the invention; Figure2 is a sectional elevational view taken substantially along the line II in Figure 1; Figure 3 is a sectional elevational view taken substantially along the line Ill-Ill of Figure 1; Figure4is a sectional detail view taken substantially along the line IV-IV in Figure 2; Figure5is aviewsimilarto Figure 4, butshowing parts of the mechanism in different orientation; Figure 6is a viewsimilarto Figure 5 and showing another relative orientation of parts of the mechanism; and Figure 7is a fragmentary plan view taken substantially along the line VII-VII in Figure 4.

An imprinter according to the present invention, and as shown in Figure 1 is desirably constructed as a generally self-contained unit having a frame structure 10 adapted to be mounted in a convenient operating position on a machine frame 11 of, for example, a packaging orfilling machine in which a workpieceWsuch asacontinuousweborfilmstrip, which may comprise a longitudinally extending series of panels that maysubsequently form individual faces of bags or packages, or labels is advanced in a stop and go fashion, and wherein panels or work areas ofthe work-piece Ware to be imprinted.

The frame 10 comprises a top plate 12 to which are secured opposite depending side plate insulating guard panels 13, a depending back plate panel 14, and a depending front plate panel 15. Attached to the top ofthetop panel 12 is a U-clamp 17 bywhichthe upper portion oftheframe loins supported on a frame bar 18extending infrontto reardirection,i.e.

transversely relative to the path of movement of the work strip W. Thereby, the housing 10 is adapted to be accurately adjusted transversely relative to the work path and then secured fixedly by means of bolts 19 tightening the clamp 17againstthebar18.

At its rear end, the horizontal frame bar 18 is mountedfixedlyon a vertical frame bar 20 which, in turn, may be mounted fixedly at its lower end on a horizontal frame bar 21 extending coextensively parallel to the upperframe bar 18. The entire frame 10 may be by means ofthe lower bar21 mounted on the machine frame 11. Although not shown, twill be appreciatedthattheframebars 18 and 21 are desirably for stability connected attheirfront ends as by means of a vertical frame barwhich may be a duplicate ofthe rearvertical frame bar 20. If preferred, the front and rear frame bars 20 may be directly attached to the machine frame 11.

Supported in a compact, unitary fashion, within theframe 10 are theworking components ofthe imprinter, comprising a print head 22, an inking roll 23, and means comprising an anvil 24 having an upwardlyfacing pressure pad 25 for supporting the workpiece Win an imprinting position with its imprintable surface facing in spaced relation toward the printing head 22.

The print head 22 comprises a block having means at one end, i.e. its upper end,for pivotal support by journal means comprising a shaft 27 rotatably supported at its opposite ends in ball bearing assemblies 28 carried bytherearframepanel 14and the front panel 15. Spaced split attachment ears 29 on the print head 22 carry split bushings 30 through which the shaft 27 extends and onto which the bushingsarefixedlysecured, after proper adjustment ofthe print head on the shaft, by means of screws 31 which draw the attachment ears 29 and split bushings 30 into firm gripping engagement relative to the shaft.Location ofthe print head 22 is closely adjacent to the front frame panel 15, with a substantial space between the rear side of the print headandtherearpanel 14. Fortolerancetakeup, means comprising a compression spring 32 mounted concentrically about the shaft 27 thrusts between the rear bearing assembly 28 and the rearmost ofthe attachment ears 29 and biases the front attachment ear 29 toward a spacer33 atthe inner sidle ofthefront bearing 28.

At its lowerend,the print head 22 hasmeansfor supporting imprinting means, comprising a forwardly and downwardly opening appropriately contoured cavity 34 within which is slidably received a type carrier 35 having a forwardly projecting manipulating handle37.Type38which may comprise any desired indicia imprinting means, is carried by the type holder 35. For retaining the type holder35 against unintentional displacement forwardly from the cavity 34, the type holder 35 may comprise a ferrous member or have a rearferrous insert or plate, and a retainer magnet39 mounted behind the type carrier on the print head releasably retains the type holder 35 in place.

Also, carried by the print head 22 is an electrical heater40 and a thermostat4l,for purposeswell known in this art.

Means are provided for cyclically swinging the print head 22 from an imprinting position with the imprinting means 38 in imprinting position spaced from the workpiece supporting means pressure pad 25, into inking relation ofthe imprinting means38to the inking roll 23, and then return ofthe imprinting means 38 to the imprinting position. To this end, the print head 22 carries fixedly on its backside a cam shoe plate 42 provided with a longitudinally extending (vertical as shown in Figures 1 and 2) cam track 43 defined between spaced rail bars 44 in the back of the shoe member 42.Riding in the track 43 is a cam follower45 carried by the distal end portion of a crank arm 47 having a proximal split end 48 drawn uptight by means of a bolt 49 onto a drive shaft 50of an oscillatably operable rotary vane pneumatic actuator 51 mounted on the backside of the frame plate panel 14. By operation ofthe actuator 51 the crank47through its follower45 and the cam track43 drives the print head 22 cyclically in a smooth accelerating and decelerating high speed mannerto and from the imprinting position of the print head 22 as shown in Figures 1,2 and 5 into inking position depicted in Figures 4 and 6, and then return to the imprinting position. The entire swinging cycle ofthe print head 22 is effected whiletheworkWis advanced in each work area increment.

For hot ink imprinting, the ink applicator or roll 23 comprises a porous elastomeric member impregnated with a heat liquifiable inking pigment.

In a preferred construction, the inking roll 23 its freely rotatably mounted within a hollow heater block 52 (Figure 4) on a cantilever shaft 53 which projects forwardlythrough an inking roll chamber52a in the heater block from a rear end cantileversupport provided bya depending rocker arm 54 having a head end 54a (Figure 3) pivotaly mounted on a bolt shaft 55 which is secured to thetop plate 12 within a forwardly opening recess 57. On the other hand, the heater block 52 is mounted fixedly to the backframe panel 14 by means of bolts 58. A back cover plate 58a is attached to the back end of the block 52. Spacers 59 maintain a predetermined spaced relation between the backframe plate 14 and the back of the heater block 52.

For conveniently mounting and removal of the inking roll 23, the roll is provided with a bearing bushing sleeve 60 (Figure 4) having mounted on its outer end a manipulating handle 61 (Figures 1 and 3) provided with a bore 62 concentric with the sleeve 60 for receiving the forward end portion ofthe shaft 53.

Thereby the inking roll 23 can be readily replaced for changing colors orfor ink replenishment.

Since the inking roll 23 is freely slidably received on theshaft 53, means comprising a latching door63 (Figures 1 and 3) are provided for retaining the roll within the heater block chamber. Conveniently, the door 63 comprises a plate which is pivotably mounted at an upper inner corner by means of a stud 64 carried by the front of the heater block 52 and having a head which serves as a thrust base for a compression spring 65 which frictionallythruststhe door 63 against the face of the block 52 and facilitates holding the door 63 in an upwardly swung open position for access into the heater block chamber. A handle 67 projecting forwardly from the lower inner portion ofthe door63faciliate shifting the door 63 between open and closed positions.An arcuate slot 68 in the door63 provides clearanceforthe handle 61 which has in its butt end portion an annular radially outwardly opening groove 69 for receiving a retaining flange 70 projecting inwardly atthe slot68.

For retaining the door 63 against unintentional dislodgement from closed, roll-retaining position, latch means are provided comprising a roll pin 63a mounted in the lower left hand portion ofthe door and arranged to project releasably into a socket 63b in the front surface of the block 52.

For inking engagement ofthe roller 23 by the imprinting means 38, the roiler 23 projects for a limited chordal extent through a lateral clearance window71 (Figure 4) atthe inner side ofthe heater block 52, and means are provided for normally biasing the inking roll toward the window 71 for assured efficient inking engagement with the imprinting means when the print head 22 is swung into the inking position. Such biasing means desirably comprise a spring biased plunger pin 72 (Figures 4-6) mounted to project from a block72a secured as by means of screws 73 (Figure 3) to the rearframe panel 14.The biasing plunger 72 thrusts against a shoulder 74 on the lower end portion ofthe rockerarm 54,thustendingto swing the arm inwardly, that is, clockwise as viewed in Figures 4-6.

To avoid overthrustofthe inking roll 23 underthe biasing influence ofthe plunger 72, an eccentric stop shoulder75 (Figures 1 and 4-6) is mounted by means of a retaining screw 77 to be engaged bya shoulder 78 on the lower portion ofthe rocker arm 54 opposite the th rust shoulder 74.

In addition to the spring biased positioning of the inking roll relativeto the imprinting means38,means are provided for avoiding cornering ofthe printing means 38 against the perimeter of the inking roll, as well asfordriving the inking roll in coordinated relation with the print head, in the cyclical swinging of the print head 22 relative to the inking roll.To this end, there is mounted in free wheeling rotary relation on the cantilevershaft 53, in thespace behindthe heater block 52, buffer and driver means comprising a wheel 79 (Figures 3,5,6 and 7) which carries a resilienttire 80 such as an O-ring of the same diameter as the roll 23 and on which an arcuate cam surface 81 atthe lower end ofthe shoe 42 rides in the upward inking swing ofthe print head 22 before the imprinting means 38 makes contact with the inking roll 23.As the shoe cam surface 81 rides thetire 80 (Figure 6), it pushes the wheel 79 counterclockwise in opposition tothe bias ofthe plunger72 to maintain the inking perimeter of the roll 23 free from the imprinting means 38 until the approaching corner of the imprinting means 38 has reached the tangent of the relativelyflatface of the imprinting means 38to the inking roll perimeter. Thereupon, a surface 82 on the shoe 42, extending parallel to the surface of the type face of the imprinting means 38, rides onto the tire80 and thus permitsthe biasing plunger72to cause the ink roll to be biased toward and againstthe imprinting means 38 (Figure 4).

As the inking stroke upswing ofthe print head 22 continuestotheend of the inking stroke as indicated in the dash double dot phantom position in Figure 6, a substantially uniform ink application is attained.

There is an arcuate cam surface 83 on the opposite side of the surface 82 from the cam surface 81. The cam surfaces81 and 83 areformed on the same radius ofcurvature. At the offrunning side ofthe imprinting means 38 the cam surface 83 is adapted to engagethe tire 80 and shiftthe inking roll 23 away from the offrunning side corner of the imprinting means. However, upon reversal of the swinging movement of the print head 22, the imprinting means 38 will again contactthe inking roll 23 in ink receiving relation until the cam surface 81 is reached and the tire 80 and wheel 79 cause the inking roll 23to shift away from the imprinting means 38.

For maximum inking efficiency, the inking roll 23 and the wheel 79 arecorotative. Therefore, a multi-jaw coupling comprising a jaw 60a (Figure 3) at the inner end ofthe sleeve 60 couples with a complementary jaw 79a projecting forwardly on the hum ofthe wheel 79.

The cam surfaces 81,82 and 83 on the shoe 42 will contact the resilient tire 80 with sufficient force to cause rotation of the resilient tire 80, and therefore the wheel 79, thereby corotating the inking roll 23 on the sleeve 60, with which thewheel 79 is coupled.

Contact between the tire 80 and the cam surfaces is effected smoothly and without causing any bouncing ofthe wheel 79 which might overcome the plunger 72 and causethe imprinting means 38 notto fully contact the inking roll 23.

Due to the velocity of return travel of the print head 22, as the imprinting means leaves the perimeter of the inking roll 23, the inking roll is impulsed bythe tired wheel 79 as it runs off of the print head, to free wheel at least a short distance, so that in the next cycle the imprinting means 38 will contact a fresh area ofthe inking roll perimeter.

It will be appreciated, of course, that where heat liquifiable inking pigment is employed, appropriate heating means must be carried bythe heating block 52. For example, as best seen in Figures 1 and 4, a pair of heaters 84 may be carried in appropriate pockets in the block, as well as a heat controlling thermostat 85. Not only the heaters 84, but also the heater 40 carried by the printhead 22 are connected in electrical energy circuits controlled by the thermostats 41 and 85 in a well known mannerand therefore specific circuitry for this purpose has been omitted.

For improved operating speed, instead of the print head 22, being driven againsttheworkW, theworkW isdriven bytheanvil 24and pad 25toward and against the imprinting means 38 when the print head 22 is in the imprinting position depicted in Figures 1 and 2.As shown in full outline, the pad 25 is normally in spaced relation below the imprinting means 38, and is arranged to be thrust upwardly by the anvil 24 to pushtheworkpieceWtoward and into imprinting engagement with the imprinting means 38 as shown in dot dash outline.Actuation ofthe anvil 24forthis purpose is effected by means of a rectilinearly operating aircylinder actuator87 mounted in properly adjusted position on the lowerframe bar 21 by means of a base flange 88 secured by means of a U-clamp 89 tightened up by means of bolts 90. If preferred, the base flange may be secured directly to the machine frame 11. A piston rod or ram 91 extends upwardly reciprocablythrough the top ofthe cylinder ofthe actuator 87 and engages in a downwardly opening recess in the base plate 92 which has a central clearance hole 92a. Means comprising a bolt 93 and a split lockwasher 92b secures the base plate 92 to the piston rod 91.The head ofthe bolt93 extends upwardly into a clearance recess 93a on the underside ofthe anvil 24. The recess in the underside ofthe plate 92 and the clearance recess 92a on the underside ofthe anvil 24 are for the purpose of reducing the overall height of the assembly.

Vertically adjustable screws 94 threaded upwardly through a base plate 92 adjustably support the anvil 24 on the base plate. When the anvil 24 has been properly adjusted relative to the base plate 92, a pair of securing screws 94a which extend upwardly through the base plate 92 and are threaded into the anvil 24, are tightened to lockthe assembly in operating relation. To hold the base plate 92 and thereby the anvil assembly against rotation relative to the actuator 87, means comprising an anti-rotation pin 95 fixed to the top of the actuator 87 projects up in closelyslidablerelationthrough a pin bore 96 in the plate 92.

Means are provided for coordinated control ofthe print head swi ngi ng actuator 51 andtheanvil reciprocating actuator 87 in accordance with stop and go, i.e. panel by panel, duty cycle advance ofthe continuousworkpiece Which is provided with detectable means such as identifiable color spots 97 shown in highly exaggerated form for illustrative purposes in Figure 1.These color spots 97 are so locatedthatwhen a detector 98 observes from the spots 97 that a panel ofthe workWto receive an imprint is in proper position to the print head 22 for imprinting, a signal is sent to a control device 99 which causes a pneumatic valve 100 to be actuated for supplying air pressure to the actuator 87 for driving the anvil 24 in an imprinting stroke from which the anvil is immediately retracted to release the work W for onward movement. Promptly upon resumption of onward movementoftheworkW,a detector 101 is activated by the leading spot 97 and a signal is sent to the control 99 which through a pneumatic valve 102 activates the rotary actuator 51 for driving the print head 22 in a continuous cycle inking stroke and return to the imprinting position in the shorttime it takes for the work Wto advance one panel orworkarea increment.

By virtue ofthe smoothly operating high speed swing actuating mechanism for the print head 22, wherein the crank 47 rotates 270 in each direction while causing the print head 22 to swing 90 in each direction, extremely rapid cycling ofthe print head 22 from the imprinting position through the inking stroke and return to the imprint position is accomplished, so that imprinting can be effected at high speed coordinated with the rapid advance and momentary dwell in the duty cycle of the work W.

Although the advance of each panel ofthe work W is quite rapid and dwell very short, imprinting by actuation of the actuator 87 coordinated with the short imprinting dwells in the print head cycle, coordinated with the intermittent advance of work W, is accomplished smoothly and efficiently.

It will be understood that variations and modifications may be effected without departing from the scope ofthe appended claims.

Claims (16)

1. An apparatus for imprinting a workpiece having an imprintable surface, comprising: (1) a journal supported by a supporting frame on a fixed axis; (2) a print head having one end pivotallysupported bythejournal and carrying imprinting means by an opposite end; (3) meansforsupporting theworkpiece in an imprinting position with its surface facing toward the print head but spaced from the imprinting means; (4) inkapplicatormeansmountedontheframe; (5) meansforcyclicallyswingingthe print head from an imprinting position with the imprinting means in an imprinting position spaced from the workpiece supporting means, into inking relation of the imprinting meanstothe ink applicator means, andthen return ofthe imprinting meanstothe imprinting position; and (6) means operable when the print head is in the imprinting position for driving the workpiece supporting means and the workpiece supported thereon toward the imprinting means so that the imprintable surface is pushed by the action ofthe supporting means into imprinting contact with the imprinting means.

2. An apparatus according to claim 1, wherein the journal comprises a shaft having opposite ends journalled in a bearing on the frame and the print head comprises a block having one end adjustably secured to the shaft.

3. An apparatus according to claim 2,whereinthe cyclical swinging means (5) comprise a straight cam track extending between the ends of the block, a crank arm having a follower in thetrack and a rotary actu ator for driving the crank oscillatably for rapid accelerating and decelerating swinging movement ofthe print head.

4. An apparatus accordingto claim 1,2or3, wherein the ink applicator means (4) comprise an inking roll carried rotatably in a pivotally mounted heating block, means normally biasing the heating block so asto place the inking roll in position for inking the imprinting means in the cyclical swinging ofthe print head, and means for controlling the biased position ofthe heating blockforcontrolling engagement ofthe imprinting meansagainst damaging the inking roll in inking contact ofthe imprinting means during swinging of the imprinting means into the imprinting position.

5. An apparatus according to claim 4, wherein the heater block is pivotally mounted by means of a rocker arm which carries a control wheel engageable with a control cam surface carried by the print head for controlling inking contact of the inking roll with the imprinting means during the inking phase ofthe swinging cycle ofthe print head, the inking roll and the control wheel being connected corotatably.

6. An apparatus according to any preceding claim, wherein the workpiece supporting means (3) comprise an anvil and an actuator is provided for cyclically driving the anvil for effecting imprinting contact.

7. An apparatus according to any preceding claim, wherein the cyclical swinging means (5) comprise a pneumatic actuator, the driving means (6) comprise a pneumatic actuator and means are provided for coordinating operation ofthe actuators.

8. An apparatus according to claim 7, wherein the first actuator comprises a rotary actuator and the second actuator comprises a rectil i nea rly-operating cylinderactuator.

9. An apparatus according to any of claims 1 to 3, wherein the ink applicator means comprise an inking roll rotatably supported for inking engagement of the imprinting means with the inking roll in the cyclical swinging ofthe print head; means supporting the inking roll being rockably carried and means being provided for normally biasing the inking roll supporting means toward an inking position relative to the print head.

10. An apparatus for imprinting on a workpiece, which comprises a print head forsupporting imprinting means; means for cyclically swinging the print head between an imprinting position relative to a workpiece support and an inking position; means rotatably supporting an inking roll for inking engagement of the imprinting means with the inking roll in the cyclical swinging ofthe print head; means for rockably carrying the inking roll supporting means; and means for normally biasing the inking roll supporting means towards an inking position relative to the print head.

11. An apparatus according to claim 9 or 10, wherein the inking roll carrying means comprise a rocker arm and the biasing means comprise a biasing plunger engaging a shoulder on the rocker arm.

12. An apparatus according to claim 11,wherein an adjustable stop engages the rocker arm for limiting the action of the biasing means on the rocker arm.

13. An apparatus according to claim 9,10,11 or 12, including means cooperating on the print head and on the inking roll supporting means for controlling contact ofthe imprinting means with the inking roll in the cyclical movements of the print head relative to the inking roll.

14. An apparatus according to claim 13, wherein the cooperating means comprise a wheel carried by the inking roll supporting means and a cam surface carried by the print head, the wheel and the inking roll being connected corotatabiy.

15. An apparatus according to any of claims 9 to 14, wherein the cam surface is provided upon a cam shoe carried by the print head and comprising part of the means for cyclically swinging the print head.

16. An apparatus for imprinting a workpiece, substantially as hereinbefore described with reference to the accompanying drawings.