DISPENSER FOR USE WITH A POLYURETHANE MIXING HEAD

DISTRIBUTEUR POUR TETE DE MELANGE DE POLYURETHANE

English Abstract

A spinning cone is positioned directly below a mixing head outlet to dispense and distribute a sticky mixture of polyurethane foam liquid chemical components. The mixing head and cone are reciprocated together across a longitudinally advancing metal strip to substantially uniformly distribute the mixture thereon. The procedure is practised in connection with the fabrication of overhead door insulated panels. In the prior art, plugging of dispensers would commonly occur within minutes, due to a build-up of adhering mixture on a surface followed by foaming. The spinning cone has dispensed satisfactorily for hours at a time.

French Abstract

Un cône rotatif est placé directement sous la sortie d'un dispositif de mélange pour distribuer et diffuser un mélange collant de composants chimiques liquides en mousse de polyuréthane. Le dispositif de mélange et le cône sont en mouvement alternatif à travers une bande métallique avançant longitudinalement pour distribuer uniformément et amplement le mélange. La procédure est pratiquée dans le cadre de la fabrication de panneaux de portes de garage isolés. Dans l'état de la technique, le colmatage des distributeurs se produit généralement en quelques minutes, en raison d'une accumulation du mélange adhérent sur une surface, suivie par la formation de mousse. Le cône rotatif a effectué la distribution de manière satisfaisante pendant des heures d'affilée.

Claims

THE EMBODIMENTS OF THE INVENTION IN WHICH AN
EXCLUSIVE PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS
FOLLOWS:
1. A method of applying a liquid mixture of polyurethane foam
components onto a top surface of a metal strip being advanced longitudinally,
comprising:
delivering a stream of the mixture from a mixing head having an outlet
onto the apex of a spinning cone positioned directly beneath the outlet and
above the strip, to dispense the mixture onto the strip; and
reciprocating the mixing head and cone together transversely across
the longitudinally advancing strip to evenly distribute the dispensed mixture
across the top surface of the strip.
2. The method as set forth in claim 1 wherein:
the mixture is dispensed as bands having side edges and extending
across the top surface of the strip and the bands overlap along their side
edges.
3. A reciprocating mixing/dispensing assembly for delivering a mixture
of polyurethane foam components onto a longitudinally advancing strip,
comprising:
a mixing head, having an outlet, for mixing the components and
producing a mixture thereof through an outlet;
a cone, having an apex positioned centrally beneath the outlet;
means for spinning the cone to dispense the mixture onto the strip; and

means for reciprocating the mixing head and cone together across the
strip to distribute the dispensed mixture thereon.
10

Description

CA 02301376 2000-03-20
1 FIELD OF THE INVENTION
2 The present invention relates to an assembly and process for applying
3 a mixture of chemical components, for producing polyurethane foam, onto a
4 longitudinally advancing metal strip. The invention finds application in the
production of foam-insulated panels used in overhead doors, insulated
6 building panels and insulating board.
7
8 BACKGROUND OF THE INVENTION
9 It is conventional to produce foam-insulated panels as follows:
~ a pair of metal strips, one spaced directly above the other, are
11 advanced together;
12 ~ a mixingldispensing assembly is positioned between the strips. The
13 assembly comprises a polyurethane mixing head having an
14 attached dispenser, for admixing the polymerizable chemical
components (organic resin and polyisocyanate) which react to
16 produce polyurethane foam and delivering the produced ,mixture
17 onto the lower strip;
18 ~ the mixingldispensing assembly is reciprocated transversely aaoss
19 the advancing lower strip to distribute the mixture thereacross; and
~ the strips then converge closer together and are advanced through
21 a long heating oven to cause the mixture to foam, fill the space
22 between the strips and solidify into insulating polyurethane foam
23 which is bonded to the two strips.
2

CA 02301376 2000-03-20
1 There are a number of commercially available mixing heads on the
2 market for mixing the chemical components. A typical example brings
3 separate streams of the two polyurethane foam-produdng components
4 through a pair of passageways formed in the mixing head and discharges
them under pressure through opposed outlets into a mixing chamber and an
6 angularly positioned port leading to the dispenser. The components mix
7 turbulently as they meet and proceed together through the chamber and port.
8 There are also a number of commercially available dispensers, each of
9 which is mounted on a redprocating arm or carriage, for distributing the
foam
mixture produced by the mixing head onto the moving strip. For example, one
11 known dispenser is a tube, perforated along its length and dosed at its
outer
12 end, which delivers the mixture in the form of a plurality of parallel
streams of
13 small diameter. A second known dispenser is a hopper-like nozzle having a
14 bottom slot which delivers the mixture in the form of an elongate, thin
curtain.
In connection with these assemblies it is desirable:
16 ~ that the components be well mixed;
17 ~ that the mixture be evenly distributed over the bottom strip; and
18 ~ that the assembly not plug readily , so that it can operate for several
19 hours without interruption.
However, in our experience these objectives have not been achieved
21 using the commercial mixingldispensing assemblies heretofore available. In
22 our testing with a variety of mixing heads and dispensers, of conventional
23 design and of our own design, we repeatedly experienced rapid plugging,
24 often within a few minutes. The chemical mixture is very sticky and tends
to
adhere to the metal surface of the mixing head port and to the internal
3

CA 02301376 2000-03-20
1 surfaces of the dispenser. The adhering material will foam up and plug one
or
2 both of these devices. In addition, even distribution of the mixture was
difficult
3 to sustain. For example, in the case of the perforated tube, some of the
4 perforations would begin to plug while others would remain open - as a
result
distribution would become uneven. There would be areas where less than the
6 optimum quantity of mixture would be deposited. These plugging and
7 distribution problems led to one or more of the following undesirable
results:
8 ~ Void spaces being present in the cured insulation;
9 ~ Poor bonding of the cured insulation to the metal strips;
~ Costly shut-downs to deal with the plugging; and
11 ~ The production of a high proportion of poor quality or defective
12 panels, with corresponding losses and customer dissatisfaction.
13
14 SUMMARY OF THE INVENTION
In accordance with the present invention, a spinning cone, having a
16 downwardly sloped surface, is positioned in spaced relation directly
beneath
17 the port outlet from the mixing head. The head and spinning cone are
18 reciprocated together across the advancing bottom strip to distribute the
19 chemical mixture along a zigzag path. Preferably the adjacent strips of
laid-
down mixture overlap along their margins.
21 It has been shown that the spinning cone is not susceptible to plugging.
22 In addition it appears to contribute to improved mixing of the chemical
23 components.
4

CA 02301376 2000-03-20
1 In a preferred feature, the cylindrical surface of the port of the mixing
2 head is coated with a non,adhering material such as Teflont'°. As a
result of
3 this change, plugging of the port has been reduced. It has also been found
4 useful to coat the top surface of the cone with Teflon or the like - the
build-up
of foam thereon is thereby reduced.
6 By combining these features, test runs of 5 - 8 hours duration have
7 been achieved without plugging. In addition, improved mixing of the mixture
8 components and uniformity of distribution of the mixture has been achieved,
9 thereby reducing the incidence of void spaces and improving bonding of the
foam to the metal skin.
11 Broadly stated, in one aspect the invention comprises a method of
12 applying a liquid mixture of polyurethane foam components onto the top
13 surface of a metal strip being advanced longitudinally, comprising:
delivering
14 a stream of the mixture from a mixing head having an outlet onto the apex
of
a spinning cone positioned directly beneath the outlet and above the strip, to
16 dispense the mixture onto the strip; and reciprocating the mixing head and
17 cone together transversely aaoss the longitudinally advancing strip to
evenly
18 distribute the dispensed mixture across the top surface of the strip.
19 In another aspect, the invention comprises a reciprocating
mixingldispensing assembly for delivering a mixture of polyurethane foam
21 components onto a longitudinally advancing strip, comprising: a mixing head
22 for mixing the components and producing a mixture thereof through an
outlet;
23 a cone, having an apex positioned centrally beneath the outlet; means for
24 spinning the cone to dispense the mixture onto the strip; and means for
5

CA 02301376 2000-03-20
1 reciprocating the mixing head and cone together across the strip to
distribute
2 the dispensed mixture thereon.
3
4 DESCRIPTION OF THE DRAWINGS
Figure 1 is a schematic side view showing the mixing dispensing
6 assembly positioned between converging, longitudinally advancing metal
7 strips, arranged for the production of insulated panels;
8 Figure 2 is a perspective view of the assembly distributing chemical
9 mixture onto the lower strip;
Figure 3 is a partly sectional side view of the mixing head, dispenser
11 and drive means; and
12 Figure 4 is a fanciful plan view of the overlapping strips of chemical
13 mixture laid down by the assembly.
14
DESCRIPTION OF THE PREFERRED EMBODIMENT
16 As shown in Figures 1, 2 and 4, a mixingldispensing assembly 1 is
17 mounted on a conventional reciprocating arm 2. The assembly 1 is positioned
18 between top and bottom metal strips 3,4. The strips 3,4 are advanced
19 longitudinally while the assembly 1 is reciprocated back and forth. The
assembly 1 includes a polyurethane mixing head 5 and a dispenser 6. The
21 dispenser 6 comprises a spinning cone 7 positioned centrally beneath the
22 outlet 8 of the mixing head 5. The mixing head 5 is operative to produce a
23 pressurized stream 9 of a mixture of chemical components which produce
24 polyurethane foam when cured by heat. The spinning cone 7 is operative to
6

CA 02301376 2000-03-20
1 dispense the mixture 10 in the form of a band 11 following a zig-zag path 12
2 back and forth across the top surface 13 of the bottom strip 4.
3 The mixing head 5 is conventional. It has separate passageways 14,
4 15 connected to hoses 16, 17 for the supply of chemical component streams
18, 19 of resin and polyisocyanate respectively. The passageways 14, 15
6 discharge the streams 18, 19 through opposed orifices 20, 21 into a mixing
7 chamber 22. The mixing chamber 22 connects with a port 23 formed by a
8 perpendicularly oriented tubular port member 24. The inner surface 25 of the
9 port member 24 is coated with a layer 26 of Teflon. The port member 24 is
screw-threaded into the mixing head body 5a.
11 The mixing head 5 is mounted by a bracket 27 and screws 28 to the
12 reciprocating arm 2.
13 The dispenser 6 comprises a cone 7 and means 40 for spinning the
14 cone. The spinning means 40 comprises a motor 29 mounted to the arm 2 by
bracket 30 and screws 31. A bearing assembly 32 is secured to the end of
16 the port member 24. A pulley 33 is rotatably mounted on the bearing
17 assembly 32. A drive belt 34 connects the motor output shaft sheave 35 with
18 the pulley 33. A plurality of holder wires 36 are connected with the sheave
33
19 and support the cone 7. As shown, the apex 37 of the cone 7 is positioned
directly below and close to the outlet 8 of the mixer head port 23. The cone
21 apex 37 is aligned with the axis of 'the port 23. The surface 42 of the
cone 7 is
22 coated with Teflon' .
' Trade Mark
7

CA 02301376 2002-06-10
1 In operation, the arm 2 is reciprocated to move the mixing/dispensing
2 assembly 1 back and forth across the advancing bottom strip 4. The means
3 40 rotate or spin the cone 7. The mixture stream 9 issuing under pressure
4 from the port outlet 8 strikes the downwardly sloped, spinning top surface
42
of the cone 7 and is dispersed and thrown outwardly to deposit as a band 11
6 on the surface 13 of the bottom strip 4. The band 11 follows a zig-zag path
12
7 across the strip. The rate of advance of the strip and rate of reciprocation
of
8 the mixing/dispensing assembly are co-ordinated so that the bands 11 overlap
9 slightly along their side edges.
(ET054144.DOC;1 }8

Representative Drawing