Adhesive Applicator

Abstract

A method and apparatus for applying adhesive to labels wherein a metered discrete amount of adhesive is ejected in an area related pattern onto the rear of a label from a nozzle assembly responsive to the position of the label on a delivery device.

Description

BACKGROUND OF THE INVENTION

This invention relates generally to a method and apparatus for applying adhesive and more particularly to the application of adhesive in measured discrete amounts to a label prior to the label being applied to a magazine, envelope, or the like.

There have been several prior art proposals for machines which apply labels to magazines, envelopes, or other mailing pieces in a continuous relatively high speed operation. Basically these devices use computer output which produces columns of names and addresses and other pertinent information on paper stock. The stock is then cut to the desired label size. Adhesive is applied to the back side of the label, and the label is then applied to the magazine, envelope, or other mailing piece.

Conventionally the prior art devices have utilized glue fountains and rollers for the application of adhesive to the labels. Essentially the label is moved past the roller with the underside thereof being brought into contact with the adhesive on the roller.

This technique of applying glue to the labels by means of a glue fountain has several serious drawbacks. First, it is difficult to apply a measured metered amount to each label. This raises the possibility of either an insufficient amount of adhesive being applied, resulting in an improperly adhering label, or of too much glue being applied resulting in the glue being squeezed from underneath the label onto the surface of the mailing piece where it can cause other pieces to stick thereto. Also, with the glue fountain technique of applying adhesive, there is a propensity for the glue to become smeared on the surface of the device which is transporting the label, thus causing subsequent labels to stick to this extraneous adhesive and not be properly applied to the mailing piece.

These, and other drawbacks in the glue fountain technique, such as the tendency of the glue to crust over in the atmosphere, presented certain deficiencies in this type of labeling machine.

SUMMARY OF THE INVENTION

According to the present invention, an adhesive applying device for use in a labeling machine is provided which ejects a discrete stream of adhesive in an area related pattern against the backside of a label, responsive to the label occupying a given position as it is being transported past the device. Also, preferably, the device includes means to prevent the ejection of the stream in the absence of a label occupying a preselected position.

These and other advantages will become apparent together with a fuller understanding of the invention by reference to the following description and accompanying drawings.

IN THE DRAWINGS

FIG. 1 is a plan view of an adhesive applying device, according to this invention, mounted on a label applying machine, a portion of which is shown fragmentally;

FIG. 2 is a side elevational view of the device FIG. 1;

FIG. 3 is a sectional view taken substantially along the plane designated by the line 3--3 of FIG. 1 and drawn to a larger scale than FIGS. 1 and 2;

FIG. 4 is an enlarged detailed sectional view of the end plate and aperture therein for ejecting the adhesive;

FIG. 5 is an enlarged perspective view of the label supporting shoe and a portion of the drum carrying the shoe with parts exaggerated for clarity of illustration;

FIG. 6 is a sectional view taken substantially along the line 6--6 of FIG. 5;

FIG. 7 is a view of the backside of a label showing somewhat diagrammatically the assumed pattern of the adhesive after it has been ejected thereon and before the label is applied to a surface;

FIG. 8 is a view similar to FIG. 7 showing the assumed pattern of the adhesive after application of the label to a surface in the absence of a dam and ribs according to this invention; and

FIG. 9 is a view similar to FIG. 8 but showing the assumed pattern of the adhesive after application of the label to a surface when a dam and ribs are utilized.

DESCRIPTION OF THE PREFERRED EMBODIMENT

General Environment

Referring now to the drawings, and for the present to FIGS. 1 and 2, an adhesive applying device, designated generally as 10, is shown incorporated in a label applying machine, a portion of which is shown fragmentally at 12.

In the device as utilized in the preferred embodiment, the machine delivers single labels successively to a rotating drum 14 at about the 3 o'clock position as viewed in FIG. 2. The drum 14 is provided with a label support shoe 15 which has a series of openings 16 connected to a low pressure apparatus, not shown, to thereby create a pressure differential at the shoe surface. The pressure differential holds each label, one of which is shown in phantom at 18 in FIG. 1, against the shoe as the drum rotates counter-clockwise as viewed in FIG. 2. As the drum rotates, it carries each label 18 past an adhesive applying station, designated generally as 20, at about the 9 0'clock position as viewed in FIG. 2, where adhesive is applied by the adhesive applying device 10 to the exposed rear or underside surface of the label. The label is then rotated by the drum into contact with a mailing piece, such as a magazine shown in phantom in FIG. 2 at 22, at the 6 o'clock position where it is applied to the mailing piece. The mailing pieces 22 are transported in synchronized relationship with the drum to pass a mailing piece 22 upon each rotation of the drum.

Glue Applicator

Turning now to the adhesive applying device 10, said device includes an adhesive reservoir in the form of a removable and replaceable plastic bottle 24 which through a tube 26 supplies adhesive to an applicator head, designated generally as 30. The adhesive is ejected in discrete streams from the applicator head by actuation of an actuating arm 32, pivotally mounted at one end thereof by a pivot pin 34, shown in FIG. 1. The actuating arm 32 is operable by means of a cam assembly 36 which is carried by the drum 14. A roller cam follower 37 is mounted on arm 32. As the cam assembly 36 rotates past the 9 o'clock position the cam assembly strikes roller cam 37 causing the arm to pivot around the pin 34. The arm 32 operates associated pumping apparatus to cause an emission of metered adhesive from the applicator head 30.

The structure of the adhesive applying device which will cause the emission of the adhesive is shown in detail in FIGS. 3 and 4. The applicator head 30 includes a main body 38 having a chamber or cavity 40 formed therein. Cavity 40 has an outer and inner portion divided by an annular wall or ring section 43. The cavity 40 has disposed therein a piston assembly, designated generally as 42, which is slidably mounted within the annular wall ring section 43. The piston assembly 42 is retained within the cavity by means of a snap ring 44 and is sealed within the ring section 43 by O-ring 45.

The piston assembly 42 includes a piston 46 which is biased into contact with the snap ring 44 by means of a piston return spring 48 surrounding the ring section 43 within the cavity 40. Piston assembly 42 is short of the depth of the cavity 40 to create an end cavity area 40A.

The piston 46 has a partially threaded axial bore in which a sleeve 50 is threaded. The sleeve 50 has a central bore 52 at the rear or the left hand end thereof, as viewed in FIG. 3, and counter bore 54 in front or on the right side as viewed in FIG. 3, connected to produce a through bore or orifice. Disposed within the bore 52 is a ball type check valve 56 which seats against O-ring seal 58. The ball check valve 56 is normally biased into engagement with the O-ring 58 by means of a spring 60 of a known selected preload force. The spring 60 is retained within the bore by means of a pin 62 extending through the sleeve member. If a body of fluid is captured in cavity area 40A, and piston 46 is forced into the cavity, the trapped fluid can escape past the ball valve 56, but cannot return. Thus, actuation of the piston produces a pumping action.

A nozzle assembly, designated generally as 64, is carried in abutment with piston 46 as a part of piston assembly 42. Assembly 64 includes a nozzle plate 66 having an aperture 68 formed therein. See FIG. 4.

The nozzle assembly 64 is provided with a pair of arm 32 engaging cap pins 70. A force applied to the cap pins 70 will drive the assembly 42 into the cavity 40 and produce the pumping action. Such pumping action will force fluid out through aperture 68. As can best be seen in FIG. 4, the aperture 68 at the discharge end thereof has an outwardly flaring conical configuration indicated by the reference character 74. On the inside of the nozzle plate 66 is a raised annular ridge 76 surrounding the aperture 68.

Referring again to FIG. 3, the cavity area 40A as viewed in FIG. 3 is supplied with adhesive duct 78 which communicates through unidirectional check valve assembly 80 and tube 26 with the adhesive bottle 24. Whenever piston 46 moves into cavity area 40A, the fluid is trapped by check valve 80 and cannot escape back through the tube 26. A second duct 82 is also provided in communication with the cavity area 40A through a normally closed solenoid valve 84 to the bottle 24. Hence fluid cannot normally escape through duct 82.

In operation of the device, first assume that the left hand side of the cavity, as viewed in FIG. 3, and the central bore 52 of the sleeve 50 are filled to capacity with liquid adhesive. In this condition, with movement of the piston assembly 42 to the left as viewed in FIG. 3, the pressure in the cavity will start to increase. The increasing pressure will close ball check valve 80 to prevent escape of adhesive through duct 78 and valve 84 being closed prevents adhesive from returning to the bottle therethrough. The forces will continue to increase with the continued movement of the piston assembly to the left until the internal hydrostatic force exceeds the preload of the spring 60. When this preload is exceeded, the check valve 56 will unseat from the O-ring 58 and the hydrostatic forces will cause the adhesive within the sleeve 50 to discharge through bore 52 and aperture 68 in a discrete stream until the pressure has been relieved. The discharge will continue once the preload of the spring 60 has been exceeded as long as movement of the piston assembly 42 continues to the left. When this movement stops, the forces will then become equalized and the spring 60 will cause the check valve 56 to seat against the O-ring 58. Thus, a discrete specific amount of adhesive will have been emitted from the aperture 68. The metered amount and velocity will depend upon the preload of the spring 60 and the length of the travel of the piston assembly 42.

Further, the rate of discharge, i.e., volume per unit time will vary directly as the speed of movement of the piston. Hence if a label is traveling a given speed the volume of adhesive reaching any given location of the label can be varied by varying the speed of movement of the piston which will thus vary the pattern of the adhesive on the label. The speed of movement of the piston can be controlled by the shape of the cam.

During the discharge period the bore 52 and counter bore 54 in the sleeve 50 act as a venturi. It has been found that in this venturi type configuration passage 52 together with the counter bore 54 helps to provide a uniform stream which will have a sharp cut-off point at the completion of the ejection operation. If a uniform diameter bore is utilized, the cut-off of the stream ejection is characterized by a tendency of the device to suck back a portion of the stream, causing the stream to "whip" and be deposited on the equipment. Also with a uniform bore diameter the end of the stream ejection is characterized by a relatively slow decay or decline of forces which results in the adhesive oozing from the aperture. The variable diameter configuration of the bore of the present invention eliminates these tendencies by providing a quick shut off with rapid decay of forces.

Once the force urging the piston assembly to the left is removed, the piston return spring 48 will cause the piston assembly 42 to return again to its full forward position as shown in FIG. 3. This will cause a low pressure within the central bore 52 and the cavity area 40A. This low pressure will cause the ball check assembly cavity 80 to open, allowing adhesive from the bottle 24 to move through the tube 26 and the duct 78 to thereby resupply the bore 52 and the cavity area 40A.

Refer to FIGS. 1 and 2. When the cam follower of actuating arm 32 is engaged by the cam assembly 36, it will be urged to the left as viewed in the FIGS. 1 and 2 and will cause the arm 32 to pivot about the pin 34. Arm 32 bears against the cap pins 70 and will drive the piston assembly to the left causing a discharge of a discrete stream of adhesive through the aperture. This discrete stream of adhesive is aimed by aperture 68 to strike the backside of the label at the adhesive applying station 20, thus applying adhesive to the label.

The amount of adhesive in the stream can be changed by changing the initial angular position of the arm 32. For example, if the arm 32 is moved pivotally clockwise as viewed in FIG. 1, it will force against the cap screws 70 moving the piston assembly 42 to the left. Thus, if the starting point of the piston stroke is in a position with the arm moved clockwise, the total movement of the piston assembly will be less. Therefore a lesser amount of adhesive will be ejected. The more this initial amount is to the left, the less the amount that will be emitted.

The adjustment of the arm 32 can be accomplished by means of a bolt 90 passing through the actuating arm 32 and a flange 92 on the body 38 engaged by an adjusting nut 94. The adjustment of the adjusting nut 94 will change the angular position of the arm 32 and thereby allow for an adjustment of the amount of adhesive to be discharged for a particular label length.

As was indicated above, and as shown schematically in FIG. 3, the valve 84 is a normally closed solenoid valve which can be opened by the solenoid action thereof. This solenoid action is controlled by a photoelectric cell which is shown schematically at 96, and is used to cause recirculation of the adhesive in preference to emission when a label is not in proper position or is missing. The photoelectric cell is positioned and aimed at the rotating drum 14 so as to scan a given position thereon at selected periodic intervals to detect the presence or absence of a label with each scan. If the scan detects the presence of a label, the solenoid is not actuated, and the valve remains closed. However, if the photoelectric cell detects the absence of a label at the given position on the scan, it will actuate the solenoid to open the valve. At the open condition of the valve, when the piston assembly 42 is moved to the left, the adhesive within the bore 52 and the left hand portion of the cavity area 40A will flow through the passage 82 and the open valve 84 back to the bottle 24, since this is the path of least resistance because of the preload in the spring 60. Thus the cam assembly 36 will actuate the actuating arm 32, the point of the actuation being related to the position which a label should occupy; however, when there is no label or when the label is out of such position even though the cam is actuated, ejection will be prevented by recirculation of the adhesive.

As can be seen in FIG. 2, the cam assembly 36 is comprised of a pair of identically shaped cam members which are slidably mounted on bolts 98. These bolts can be loosened so that the cams can be moved to adjust their position. It is apparent therefore, that the cams can be slid so that they are in fact coincident with each other, in which case, each rotation will provide a single cam actuation of the device. However, if the cams are spaced as shown in FIG. 2, for each rotation there will be a double actuation, this type of actuation may be desirable whenever a relatively long label is being utilized, and thus it will be given a double application of adhesive.

If a wider label is used than can be covered by a single stream of adhesive, a second aperture similar to aperture 68 can be formed beside it so that a double stream is emitted on each actuation.

One of the outstanding advantages of the present invention is the ability of the device to be used intermittently with relatively little, if any, maintenance required before each start-up, even with hours or several days lapse between usage. At most, all that is required is that any uncovered bubble which is apparent externally around the aperture 68 be removed, and with the present configuration of the device, even this is usually not necessary. The annular ridge 76 around the aperture internally of the device acts as a dam, or stop, which prevents seeping of the adhesive through the aperture 68 during down time, so that there usually is no encrusted bubble to remove. The flaring conical portion, or chamber 74, also helps to prevent the formation of a bubble.

Referring now to FIGS. 5 and 6, the improved label support shoe 15 is shown in detail. The shoe 15 has an arcuate surface 100 and a pair of spaced ribs 102 at opposite sides thereof extending longitudinally in the direction of travel of the shoe. These ribs preferably are raised 0.003 - 0.005 inch above the surface 100, for conventional weight labels and are shown exaggerated for clarity of illustration.

Openings 16 are provided in the ribs 102 through which a low pressure is applied to hold a label on the shoe 15 by pressure differential. A label 18 is shown in phantom outline in FIG. 5

The shoe 15 has a raised ridge, or dam 104, extending upwardly from the surface 100. Assuming the use of labels of conventional thickness the dam 104 preferably extends upwardly about 0.012 inch, but is shown greatly exaggerated for illustration purposes. The dam 104 extends transversely across the surface 100 and is located nearer the leading edge of the label than the trailing edge thereof when the label is supported on the shoe.

The dam 104 is provided for the purpose of obtaining a better spread or distribution of adhesive at the leading edge of the label, and the ribs 102 are provided to minimize any tendency of the adhesive to squeeze out of the sides of the label.

How these objective are achieved can be best understood by reference to FIGS. 7 through 9.

FIG. 7 shows the rear of a label having had ejected thereon a discrete amount of adhesive. The rotation of the head 14 and the pattern of the adhesive ejection causes the adhesive to assume a pattern as diagrammatically shown in solid outline having an enlarged "head" with a narrow "tail."

If the surface supporting the label were perfectly flat, the adhesive would spread generally in the pattern shown by dotted outline in FIG. 8 when the label is applied to a surface. As can be seen the adhesive spreads out generally toward and eventually to the edges of the label toward the trailing edge thereof. Hence the corners of the label at the leading edge are free of adhesive and thus not firmly adhering to the labeled piece. Also toward the trailing edge the adhesive tends to squeeze out from the side edges.

FIG. 9 shows how the dam 104 and the ribs 102 greatly improve the resultant adhesive pattern when the label is applied. The ribs retain the adhesive and thus prevent the tendency of the adhesive to spread past the edges.

Additionally, the dam 104 provides a barrier, which meters the adhesive squeezing past the dam thus the pressure instead of causing this leading part of the head to flare out toward the tail, actually causes the adhesive to return flow forwardly and evenly, as shown in dotted outline thereby providing adhesive to the corners of the leading edge of the label.

Thus according to the present invention, reliable adhesive applying devices are provided which can be easily adjusted to accommodate many variable conditions and label sizes and which require little maintenance or preparation for use even after extended down time.

Claims

I claim:

1. A system for selectively applying a fluid to a relatively moving workpiece surface, comprising in combination, structure forming at least one nozzle orifice mounted adjacent the path of the work surface for projecting pressurized fluid thereon;

a pump including a chamber and a fluid compression member movable in said chamber, said nozzle being a passageway through said fluid compression member;

transport means to carry a workpiece in a work path adjacent said nozzle, said transport means including an actuator means;

said actuator means being in the form of a cam having more than one major peak portion for fluid ejection pattern control, and said responsive means being a cam follower;

a responsive means associated with said fluid compression member and responsive to contact by said actuator means for driving said fluid compression member in a fluid compression stroke;

whereby, fluid is ejected through said nozzle as a physical pumping action of the transport means moving past said nozzle.

2. A system for selectively applying a fluid to a surface of relatively moving workpiece comprising:

at least one nozzle orifice;

pump means for supplying fluid under pressure to said nozzle orifice, said pump means comprising a chamber for receiving the fluid, piston means movable within said chamber from a first position of increased chamber volume to a second position of decreased chamber volume for pressurizing and forcing the fluid from said chamber through said nozzle orifice;

first conduit means providing fluid communication between said chamber and said nozzle orifice;

second conduit means providing fluid communication between said chamber and a source of fluid;

valve means disposed within said second conduit means and operative to permit fluid movement only in the direction from said source of fluid to said chamber, third conduit means providing communication between said chamber and said source of fluid, normally closed valve means disposed within said third conduit means, and detector means responsive to the absence of a workpiece on said carrier means and operative to open said normally closed valve means whereby fluid is recycled to said source of fluid rather than forced through said nozzle orifice;

valve means disposed within said first conduit means comprising a valve body and seat coacting to permit fluid movement only in the direction from said chamber to said nozzle orifice, said valve means opening in response to movement of said piston means from said first position to said second position;

carrier means for supporting and moving a workpiece into the path taken by fluid issuing from said nozzle orifice; and

means mounted for movement with said carrier means to move said piston means in timed sequence with the movement of said workpiece into a fluid-receiving position with respect to said nozzle orifice.