Contact type liquid applicator

A contact applicator head includes a plurality of needle valves which are each spring biased against a respective one of a plurality of valve seats, and a rotary cam actuator which when rotated retracts the needle valves away from the seats.

The present invention relates in general to a new and improved device for 
controlling the application of a liquid adhesive or the like to a member 
which is moving past the device, and it relates more particularly to a 
novel self-contained extrusion head which may be used to apply a plurality 
of glue patterns to rapidly moving webs or package materials. 
BACKGROUND OF THE INVENTION 
In the packaging field, the application of liquid adhesives to packaging 
materials is sometimes carried out by extruding the adhesives onto the 
packaging materials through orifices in a contact extrusion head. Such 
heads are commonly connected to a reservoir of the liquid under pressure, 
and a control valve is connected between the reservoir and the head. A 
problem with that type of system has been the tendency of the adhesive to 
set up in the orifices when the control valve is closed to interrupt 
liquid flow through the head. One attempt to alleviate that problem 
utilized self closing nipple-like check valve members at each orifice. 
These valves were intended to automatically seal the interior of the head 
from the ambient when liquid flow through the head terminated. Such 
attempts have not been entirely successful inasmuch as they do not 
completely eliminate the dripping or plugging of the orifices after liquid 
flow to the head is terminated. Consequently, the extrusion heads which 
are now in use require frequent cleaning and unplugging of the orifices. 
More importantly, however, unless closely watched during use, one or more 
of the orifices become plugged so that an improper pattern is placed on 
the material to be glued. When such plugging is discovered it is necessary 
to shut down the line to clean or replace the plugged head unless backup 
heads are provided. 
SUMMARY OF THE INVENTION 
Briefly, there is provided in accordance with the teachings of the present 
invention a liquid applicator head including a plurality of needle valves 
which are spring biased into the respective extrusion orifices. In a 
preferred embodiment of the invention a rotary actuator is mounted to the 
head and operates a rotary cam to retract the needles from the discharge 
orifices. A separate spring for each valve provides a positive closing 
force to close each associated needle valve whereby subsequent dripping or 
oozing of the liquid from the orifice is eliminated. The moving parts 
within the head are in communication with the liquid supply at all times 
so as to be lubricated by the liquid. The head can, moreover, be 
completely disassembled for cleaning with a solvent where necessary.

DETAILED DESCRIPTION OF THE INVENTION 
Referring now to the drawings, there is shown a self-contained liquid 
applicator head 10 of the contact type having a plurality of orifices 11 
through which a liquid is discharged in the form of a plurality of beads 
14 (FIG. 4) onto a member 12 which moves past the head in contact 
therewith. 
The head 10 includes a body member 16 having an upper cavity 18 opening at 
the top and a cover member 20 attached to the body over the cavity 16 by a 
plurality of machine screws 22. A plurality of parallel holes 24 are 
provided in the body member 16 and extend from the cavity 18 to the 
discharge orifices 11. The lower end portions of the holes 24 are as best 
shown in FIGS. 2 and 4 convergent thereby to provide frusto-conical valve 
seats 26 terminating in circular discharge openings 11 of the desired 
diameter. The holes 24 are provided at the top with internal threads 28 in 
which sleeve bushings 30 are mounted. A plurality of needle valve elements 
32 having frusto-conical forward portions shaped complimentary to the 
valve seats slidably extend through the bushings 30 with their rear ends 
extending into respective ones of a plurality of blind holes 34 in the 
cover 20. The forward ends of the needles 32 terminate at the very ends of 
the seats 26 when the valves are closed so that when the valves are closed 
there are no recesses in which any adhesive can be retained. Preferably 
the forward ends of the needs are flat and coplanar with the flat contact 
surface 35 of the body 16. 
As shown, the holes 34 are provided with counterbores 36 which respectively 
receive one of a plurality of coil springs 37. The springs 37 are 
compressed between collers 38 provided on the needle valve elements 32 and 
annular shoulders at the bases of the counterbores 36. The springs 37 thus 
bias the valves 32 individually into closed, sealing positions against the 
valve seats 26. A pair of wear plates 39 and 40 are mounted to the bottom 
faces of the body member 16. 
In order to control the opening and closing of the needle valves, a cam 
actuator member 42 is rotatably mounted in the body member 16. The member 
42 is generally cylindrical having a central section 42 which is 
hemispherical in cross-section and provided with a plurality of slots 45 
through which the valve elements 32 extend. The central section 43 has a 
planar surface 47 onto which the slots 45 open and against which the 
collars 38 are pressed by the springs 37. The cam actuator member 42 has 
cylindrical bearing surfaces 48 on both sides of the central section 43, 
and these bearing surfaces are journaled in cylindrical openings 49 and 50 
in the body member 16. Suitable seals are mounted in annular grooves in 
the bearing surface 48. 
A liquid inlet part 52 extends through the cover 20 and supplies liquid to 
the cavity 18. A plurality of holes 54, best shown in FIGS. 3 and 4 
connect the upper part of the cavity 18 to a transverse bore 55 which 
opens onto the holes 24 below the bushings 30 to provide a lower cavity 
connected to the upper cavity by the passageways 54. A plug 56 seals the 
cavity in the head from the ambient. Wherefore the cavity 18 is filled 
with liquid at all times and is sealed from the ambient when the needle 
valves are closed, and the bushings are lubricated by the liquid in the 
cavity. 
A shaft portion 60 which is integral with the actuator 42 extends from the 
housing and is rotated in order to open and close the valves. An actuating 
arm 61 is filled in a diametric slot 62 in the distal end of the shaft 
portion 60 and held in place by means of a nut 63. The shaft portion 60 
extends through a bore 65 in an actuator housing 66 having a cover 67 
suitably attached thereto by a plurality of machine screws. 
As best shown in FIG. 5, a cylindrical cavity 69 is provided in the body of 
the housing 66 and a piston 70 is mounted for sliding movement in the 
cavity 69. An actuating rod 71 on the piston slidably extends through a 
sleeve bushing 72 into engagement with the actuating arm 61. An air inlet 
fitting 74 extends through a cover plate 76 which is sealably secured to 
the housing body 66 over the cylinder cavity 69. When air is supplied 
under pressure to the line connected to the fitting 74 the arm is pivoted 
counterclockwise as shown in FIG. 5 to rotate the cam actuator clockwise 
as shown in FIG. 4 to lift the needle valve elements 32 out of the seats 
26 and thereby open the valves. When the pressure to the fitting is 
relieved, the springs 37 return the needle valve elements 32 to the seated 
positions and return the piston 70 to the upper positions as shown in FIG. 
5. For some applications it is necessary to provide additional force to 
return the piston to its initial positions. For this purpose a spring may 
be mounted in the housing body 66 or an additional pneumatic line opening 
onto the lower end of the piston may be used. 
The pneumatic actuator may be replaced with any other mechanism which is 
suitable for rotating the cam actuator 42. For example, a rotary solenoid 
may be used for this purpose. 
While the present invention has been described in connection with 
particular embodiments thereof, it will be understood by those skilled in 
the art that many changes and modifications may be made without departing 
from the true spirit and scope of the present invention. Therefore, it is 
intended by the appended claims to cover all such changes and 
modifications which come within the true spirit and scope of this 
invention.