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Claims  |
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What is claimed is:
1. A color change system for supplying selected colors of coating materials
to coating apparatus, comprising a pair of pumps each for providing
coating material to the coating apparatus; and means for selectively and
alternately connecting inlets to said pumps with supplies of coating
material and solvent for the coating material, such that said pumps
alternately provide different colors of coating material to the coating
apparatus, and such that when one of said pumps provides coating material
the other pump is connected with the solvent for continuously being
cleansed of previously provided coating material for as long as said one
pump is providing coating material.
2. A color change system as in claim 1, wherein said means for selectively
and alternately connecting comprises valve means.
3. A color change system for supplying selected colors of coating materials
to coating apparatus, comprising a pair of pumps each for providing
coating material to the coating apparatus; and means for selectively and
alternately connecting inlets to said pumps with supplies of coating
material and solvent for the coating material, such that said pumps
alternately provide different colors of coating material to the coating
apparatus, and such that when one of said pumps provides coating material
the other pump is connected with the solvent for being cleansed of
previously provided coating material, wherein said means for selectively
and alternately connecting includes means associated with each said pump
for selectively establishing a path for recirculation of solvent between
an outlet from and the inlet to the pump, and for connecting the supply of
solvent with said path to introduce solvent therein when the other pump is
connected with coating material.
4. A color change system as in claim 1, wherein each said pump is a gear
pump for accurate dosing of coating material.
5. A color change system for supplying colors of coating materials to
coating apparatus, comprising a material inlet to said system for
connection with supplies of coating materials of selected colors; a
material outlet from said system for connection with the coating
apparatus; at least two pumps, each having an inlet and an outlet; means
for cyclically and sequentially connecting individual ones of said pump
inlets and outlets with said system material inlet and outlet,
respectively, so that only one pump at a time provides a selected color of
coating material to the coating apparatus; and means for connecting said
pump inlets with a supply of solvent for the coating material when the
same are not connected with the system inlet for receiving coating
material, whereby only one pump at a time provides coating material while
the other pumps are connected with solvent for continuously being cleansed
of previously supplied coating material for as long as the one pump is
providing coating material.
6. A color change system for supplying selected colors of coating materials
to coating apparatus, comprising a material inlet to said system for
connection with supplies of coating materials of selected colors; a
material outlet from said system for connection with the coating
apparatus; at least two pumps, each having an inlet and an outlet; means
for cyclically and sequentially connecting individual ones of said pump
inlets and outlets with said system material inlet and outlet,
respectively, so that only one pump at a time provides a selected color of
coating material to the coating apparatus; and means for connecting said
pump inlets with a supply of solvent for the coating material when the
same are not connected with the system inlet for receiving coating
material, whereby only one pump at a time provides coating material while
the other pumps are connected with solvent for being cleansed of
previously supplied coating material, wherein said means for connecting
said pump inlets with the supply of solvent includes means associated with
each of said pumps for selectively establishing a path for recirculation
of solvent between the outlet from and the inlet to the pump, and for
connecting the supply of solvent with the path to introduce solvent
therein when the pump is not connected with said system inlet for
receiving coating material.
7. A system as in claim 6, including means for selectively connecting said
system inlet with a supply of flushing medium for the coating material
and/or solvent for rapidly cleaning said system and the pump which
previously provided one color of coating material of the majority of the
coating material before said pump is connected with the supply of solvent,
and for rapidly cleaning the next successive pump to provide the next
color of coating material of the majority of the recirculated solvent
before said pump provides the next color of coating material.
8. A system as in claim 7, including means associated with each of said
paths for selectively venting the same to facilitate admission of solvent
therein after the pump associated therewith is finished providing coating
material and has been cleared of the majority of the coating material by
the flushing medium.
9. A color change system for supplying selected colors of coating materials
to coating apparatus, comprising a material inlet to said system for
connection with supplies of coating materials of selected colors; a
material outlet from said system for connection with the coating
apparatus; at least two pumps, each having an inlet and an outlet; means
for cyclically and sequentially connecting individual ones of said pump
inlets and outlets with said system material inlet and outlet,
respectively, so that only one pump at a time provides a selected color of
coating material to the coating apparatus; and means for connecting said
pump inlets with a supply of solvent for the coating material when the
same are not connected with the system inlet for receiving coating
material, whereby only one pump at a time provides coating material while
the other pumps are connected with solvent for being cleansed of
previously supplied coating material, wherein the supplies of coating
material are each of the type including an outlet line, a return line and
a material supply pump for moving coating material from the supply and
through the outlet line, said color change system further including means
for connecting associated material supply outlet and return lines for
continuous flow of coating material therethrough and through the material
supplies irrespective of whether the coating materials are or are not
connected with said system material inlet, thereby to continuously agitate
the materials and prevent settling thereof.
10. A color change system as in claim 9, including a plurality of connected
system material outlets, equal in number to the number of different colors
of coating materials connectable with said system; a plurality of material
control valves, each connectable with a respective coating material supply
outlet line and return line, and with the system material inlet and an
associated one of the system material outlets; and a coating material
supply line for each said system material outlet, each said supply line
being connected at one end with its associated system material outlet and
being selectively connectable at an opposite end with the coating
apparatus when the associated color of coating material is to be provided
to the coating apparatus or to the associated material supply return line
when the associated color of material is not to be provided to the coating
apparatus, each said material control valve being operable to connect its
associated coating material supply outlet and return lines and system
inlet when the respective coating material is to be provided to the
coating apparatus, and to connect its associated coating material supply
outlet line and system outlet when the respective coating material is not
to be provided to the coating apparatus. |
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Claims |
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Description |
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BACKGROUND OF THE INVENTION
The present invention relates to color change systems for spray coating
apparatus, and in particular to improved color change systems for rapidly
changing from spraying coating material of one color to spraying material
of another color.
Color change systems for spray coating apparatus have particular
application in industrial operations where articles or ware are to be
spray coated at a spray station, or are to be coated as they move along a
production line. Where the articles are required to be coated a wide
variety of colors, it is generally not practical to establish separate
spray stations or production lines for each color, or even to spray a long
sequence of articles of one color, then another long sequence of articles
of a second color, etc. Instead, it is desirable to be able to make color
changes rapidly and simply at a single spray station.
Color change systems are useful in such cases, and provide for a variety of
colors to be sprayed from a single spray gun. With many conventional
systems, a plurality of supply containers of fluid, each of a different
color and having a separate motor driven fluid pump, are connected with a
manifold through valve controlled ports. An outlet from the manifold
connects with an inlet to the spray gun, and to spray material of a
particular color the port valve associated therewith is opened and the
motor driven pump for the supply is energized to provide the fluid through
the manifold to the gun. After completion of spraying coating material of
a particular color, the manifold and gun are flushed with solvent and
compressed air to clean the system in preparation for spraying material of
a different color.
Although the foregoing types of color change systems provide versatility in
spraying a plurality of different colored fluids with a single spray gun,
they suffer the disadvantage of requiring a separate motor driven pump for
each supply container of fluid, and are therefore expensive because of the
large numbers of pumps involved. For limited use on small production
lines, their costs often cannot be justified. In addition, requisite
manifold flushing between color changes imposes time limitations on the
color change process, which limitations may become significant in use of
high solids paints which do not flush rapidly. Consequently, such systems
also lack versatility for use with production lines in which rapid color
changes are necessary.
One prior effort to minimize the costs of color change systems of the
aforementioned type contemplates use of a single motor driven pump at the
outlet from the manifold, instead of separate motor driven pumps for each
supply container of fluid. In this case, lines extend between the valve
controlled ports of the manifold and the supply containers, whereby fluid
of a selected color may be connected through the manifold with the pump
for delivery to the spray gun. Although use of a single motor driven pump
significantly decreases system cost, the pump along with the manifold must
be cleansed between color changes, so that this type of system also
suffers from significant time delays between color changes, particularly
in use of high solids paints, which are increasingly being turned to
because of decreased environmental pollution incident to their use.
OBJECTS OF THE INVENTION
An object of the present invention is to provide an improved and economical
system for selectively spray coating a plurality of different colored
materials, and for simply and quickly changing from material of one color
to material of another color.
Another object of the invention is to provide an improved and economical
system for selectively spray coating a plurality of different colored
materials, using a pair of motor driven pumps which are alternately
connectable with selected ones of the materials and in which one of the
pumps is cleansed of coating material while the other is pumping material,
and vice versa.
SUMMARY OF THE INVENTION
In accordance with the present invention, a color change system for
supplying selected colors of coating materials to coating apparatus
comprises a pair of pumps, each for providing coating material to the
apparatus. Means are included for selectively and alternately connecting
inlets to said pumps with supplies of coating material and solvent for the
coating material, such that said pumps alternately provide different
colors of coating material to the apparatus, and such that when one of the
pumps provides coating material the other pump is connected with the
solvent for being cleansed of previously provided coating material.
In accordance with a method of the invention for supplying selected colors
of coating materials to coating apparatus with a pair of pumps, individual
ones of the pump inlets are alternately connected with selected ones of
the supplies of coating material and the pump outlets are alternately
connected with the coating apparatus, such that only one pump at a time
provides coating material to the apparatus. Also, while one of the pumps
is providing coating material, the inlet to the other pump is connected
with a supply of solvent for the coating material to clean the pump of
previously provided coating material.
The invention thus provides an improved color change system and method for
coating apparatus. By virtue of only one pump at a time providing coating
material to the coating apparatus while the other is being cleaned,
minimum numbers of pumps are required to accomplish color change
functions, whereby the structure of the system is relatively simplified
and economical.
The foregoing and other objects, advantages and features of the invention
will become apparent upon a consideration of the following detailed
description, when taken in conjunction with the accompanying drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a schematic representation of a color change system for spray
coating apparatus in accordance with one embodiment of the present
invention;
FIG. 2 is a truth table, showing one contemplated mode of operation of the
color change system in FIG. 1;
FIG. 3 is a schematic representation of a color change system for spray
coating apparatus in accordance with another embodiment of the invention;
FIG. 4 is a truth table, showing one contemplated mode of operation of the
system of FIG. 3;
FIG. 5 illustrates partly in schematic and partly in block diagram form an
arrangement of color change system for use with a hand held spray gun at a
spray booth in accordance with a further embodiment of the invention; and
FIGS. 5A and 5B show the directions of material flow in the system of FIG.
5 for material which has been selected for spraying and for material which
has not.
DETAILED DESCRIPTION
FIG. 1 schematically shows a spray gun 10 adapted to be supplied with and
to spray any one of a plurality of materials or fluids. There is also
shown one embodiment of color change system, indicated generally at 12,
for selectively supplying any one of a number of different colored
materials Cn to the gun, which are representative of a large number of
materials that can be supplied. The color change system includes a pair of
motor driven pumps P1 and P2, and a plurality of two-way valves V1-V14
which are operable to provide material of selected colors to the spray gun
through the pumps and/or flushing fluids to the pumps, such that the pumps
alternately supply different colored materials to the gun, with one of the
pumps supplying material of one color while the other is cleansed of
previously supplied fluid, and vice versa.
Specifically, lines extending to separate supply containers (not shown) of
different colored fluids C1-Cn may be selectively coupled with an inlet 14
to the color change system through associated valves VC1-VCn. Valves V1
and V6 are between the system inlet and first inlets to respective ones of
the pumps P1 and P2, which preferably are motor driven gear pumps for
accuracy and controllability in dosing, and valves V3 and V7 are between a
supply of solvent and second inlets to respective ones of the pumps, the
first and second inlets communicating with common inlet chambers in the
respective pumps. A pair of valves V2 and V4 are in series in a loop L1
between an outlet from and the first inlet to the pump P1, a pair of
valves V8 and V9 are in series in a loop L2 between the outlet from and
the first inlet to the pump P2, and dump valves V13 and V14 connect with
respective junctures of the valves V2 and V4 and the valves V8 and V9.
Valves V5 and V10 are operable to connect an outlet from a selected one of
the pumps P1 and P2 with the spray gun 10, and a dump valve V11 connects
with the spray gun material line at a point just prior to a material valve
thereof, the material valve being of a conventional type as is known in
the art and operable to emit in a spray from the gun material supplied by
either the pump P1 or P2 through the valve V5 or V10. The inlet 14 to the
color change system is also connected with a supply of flushing media
through a valve V12, the flushing media comprising alternate applications
of compressed air and a flush fluid for the coating material.
Considering operation of the color change system in relatively general
terms, the valves V1-V14 along with the pumps P1 and P2 are operable
either manually or by any suitable automatic control in a manner so that
only one of the pumps P1 and P2 supplies coating material at any one time
to the spray gun, with the other pump at that time being cleansed in
preparation for supplying a subsequent and different color of coating
material. To change color of coating material, the valves and pumps are
operated so that the pump which was previously cleaned supplies the new
color of material to the spray gun, while at the same time the other pump
is flushed clean in preparation for supplying the next subsequent color of
material.
For the case where the pump P1 supplies coating material to the gun, the
material passes from one of the valves VC1-VCn through the valves V1 and
V5 and the pump P1 to the gun, with the valves V2 and V4 then being
closed. At the same time, with the valves V6 and V10 closed and the valves
V7-V9 open, the pump P2 recirculates a cleaning solution between its
outlet and inlet through the loop L2 for cleaning the same of previously
pumped coating material. For the situation where the pump P2 provides
material to the gun, the material passes from one of the valves VC1-VCn
through the valves V6 and V10 and the pump P2 to the gun, with the valves
V8 and V9 then being closed. At the same time, the valves V1 and V5 are
closed and the valves V2-V4 are open, and the pump P1 recirculates a
cleaning solution between its outlet and its inlet through the loop L1 for
cleaning the same of previously pumped coating material. The pumps P1 and
P2 are controllable both in operation and speed of operation and where the
same are gear pumps, for long life the recirculating cleaning solution or
solvent advantageously includes a gear lubricant, for example a mixture of
a gear lubricant and a flushing fluid for the material. Between color
changes, flushing media introduced through the valve V12 quickly removes
excess coating material and/or solvent from the color change system.
The arrangement and mode of operation of the color change system enables
any number of different colored materials to be readily supplied to the
spray gun with minimum numbers of pumps, e.g., two pumps. By virtue of one
pump being cleaned while the other supplies material to the gun, changing
the color of material is accomplished very rapidly. Simply, material of
the new color is provided through the previously cleaned pump to the gun,
while at the same time the other pump is cleaned in preparation for the
next color change. Obviously, should color changes be required at
frequencies that do not afford sufficient time for cleaning a single pump
between changes, or if the time required for cleaning coating material
from a pump is greater than the intervals between color changes, more than
two pumps may be used, for example three or four. In such case, the pumps
would sequentially provide different colored materials to the gun, such
that one pump supplied material while the others were being cleaned,
thereby increasing the time available for cleaning a pump before it again
delivers material to the gun.
Considering the color change system of FIG. 1 in greater detail, and with
reference to the truth table of FIG. 2 for operation of the system, assume
an idle condition in which solvent is recirculated by the pumps P1 and P2
through the loops L1 and L2 to cleanse the same of previously pumped
coating materials. During an initial step which clears the system of the
recirculated solvent, flush and solvent are introduced to the pump P1 to
clear the pump, the loop L1 and the line to the material valve of the
spray gun 10 of previously recirculated solvent. At this time, the pump P1
is operated at a maximum rate to speed the flow of solvent and flush
therethrough, and the pump P2 at a minimum rate to continue to recirculate
solvent through the loop L2. In a following step 2, the pump P1 is then
operated at a minimum rate to move flush and solvent through the loop L1,
and flush and solvent are introduced to the pump P2 to clear the pump, the
loop L2 and the line leading to the material valve of the spray gun of
previously recirculated solvent.
To prepare the system for spraying a material of color N, a selected one of
the valves VC1-VCn is opened and, during a step 3, material is introduced
to the pump P2 while the pump is operated at a maximum rate to speed flow
of material to the spray gun. At the same time, solvent is introduced to
the pump P1 and the dump valve V13 opened to remove from the pump and the
loop L1 the mixture of flush and solvent and to fill the same with a fresh
mixture of solvent for recirculation during the time that material is
sprayed. The dump valve V11 remains open until material supplied by the
pump P2 reaches the material valve of the gun, whereupon the dump valve is
closed for spraying material during a step 4. During spraying, the pump P1
operates at a minimum rate to recirculate solvent through the loop L1, and
the pump P2 at a flow rate determined by the rate at which material is to
be supplied to the gun and until completion of spraying, whereupon in a
step 5 the pump P2 is turned off.
To prepare the system for spraying a next subsequent color of material N+1
and to cleanse the same of previously sprayed material to color N, in a
step 6 solvent and flush are introduced to the pump P2 while the same is
operated at a maximum rate and the dump valve V11 opened to remove from
the pump and its associated valves and lines the majority of the material
of color N. Then, in a step 7 flush and solvent are introduced to the pump
P1 to clean the pump and its associated lines and valves of previously
recirculated solvent, and in step 8 a selected one of the material valves
VC1-VCn is opened to introduce material of the color N+1 to the pump P1
while the pump P2 and its associated loop L2 are filled with solvent.
During step 9 material of color N+1 is sprayed, while the pump P2 is
simultaneously cleansed by recirculating solvent of any remaining material
of color N.
During spraying of material of the color N+1, the pump P1 operates at a
flow rate determined by the rate at which material is to be supplied to
the spray gun and the pump P2 at a minimum rate to recirculate solvent
through the loop L2. Upon completion of spraying material of the color
N+1, in a step 10 the pump P1 is turned off, and in a step 11 flush and
solvent are introduced to the pump P1 and the dump valve V11 is opened to
remove from the pump and its associated valves and lines a majority of
material of the color N+1. Thereafter, in a step 12 flush and solvent are
introduced to the pump P2 to clear the same of previously recirculated
solvent, and in a step 13 the system is prepared to supply the next
subsequent material of color N+2, whereupon cyclical system operation
continues as above described.
The embodiment of invention in FIG. 1 thus provides improvements in color
change systems for spray coating apparatus. By virtue of one of the pumps
P1 and P2 being cleaned while the other supplies coating material to the
spray gun, large numbers of different colored coating materials may be
accommodated by the system without use of a separate pump for each
different color of material. At the same time, the system accommodates
color changes at a rate considerably faster than may be accomplished with
prior systems of the type using a single pump which is cleansed between
color changes, particularly in use of high solids paints which ordinarily
cannot be rapidly flushed from a pump.
FIG. 3 illustrates an alternate embodiment of color change system,
indicated generally at 20, of a type generally along the lines of that
illustrated and described in respect of FIG. 1. The primary difference
between the color change systems of FIGS. 3 and 1 resides in use of a
combination of three-way valves, which minimize the number of valves
required and somewhat simplify the system. Although not shown, it is
understood that a spray gun having a dump valve at an inlet to a material
valve thereof connects with an outlet b from the valve V7 in FIG. 3, much
as the spray gun 10 connects with the juncture between the valves V5 and
V10 in FIG. 1.
Operation of the color change system of FIG. 3 is substantially the same as
that of FIG. 1, and will therefore not be described in detail. However,
suffice it to say that the operation includes alternate use of two pumps
P1 and P2 for supplying coating material to a spray coating apparatus. One
of the pumps is cleansed of a previously supplied color of material while
the other provides a newly selected color, and supplies of solvent and
flush are connectable with the pumps for purging the same and their
associated valves and lines of coating material and/or solvent. Reference
is made to the truth table in FIG. 4 for specific details of operation of
the color change system of FIG. 3.
The color change systems 12 and 20 illustrated in FIGS. 1 and 3 are
particularly adapted for automatic spray painting operations wherein both
the systems and the spray painting apparatus are under automatic control,
for example in production lines where articles are required to be coated a
wide variety of colors. However, the systems may also be readily adapted
to manual spray painting operations, and FIG. 5 illustrates such an
arrangement. In this case, a color change system 12 or 20 is shown as a
block, and includes solvent and flush inlets as well as a dump outlet. As
compared with the systems of FIGS. 1 and 3, only a single dump outlet is
illustrated, it being understood that the same would be common to outlets
of the valves V13 and V14 in use of a system 12 of FIG. 1, or the outlets
a and c of the respective valves V5 and V9 in use of a system 20 of FIG.
3.
Assuming that the color change system is of the type shown in FIG. 1, the
apparatus of FIG. 5 also includes a plurality of material valves VC1-VCn,
each of which connects with a port a of an associated control valve
VC1'-VCn'. A port b of each valve VC1'-VCn' connects with an associated
supply container of material of a particular color, and an outlet
distribution manifold (not shown) has an inlet connected with the color
change system outlet (with the juncture between the valves V5 and V10), a
plurality of material outlets having material outlet valves M1-Mn and a
flush outlet connected with the dump outlet. A port c of each valve
VC1'-VCn' connects with a material return line to the respective material
container with which the port b of the valve connects, and a port d of
each valve connects with an associated one of the manifold outlet valves
M1-Mn.
The port d of each valve VC1'-VCn' and its respective manifold outlet valve
M1-Mn are each connected with one end of an associated hose H1-Hn at a
material distribution panel 100 of a spray booth, a check valve 102 is at
an opposite end of each hose, and the port c of each valve VC1'-VCn' is
also coupled with an associated check valve 104 at the distribution panel.
Normally, the end of each hose H1-Hn, which includes the check valve 102,
is connected through a releasable coupler 106 and an associated check
valve 104 with the return line to its associated material container, the
couplers opening the associated check valves 102 and 104 upon the mating
portions of the couplers being joined. However, each coupler is releasable
from its connection with its material return line for coupling the hose
with a hand held spray gun 108, which closes the associated check valve
104 but opens the check valve 102 upon connection with the spray gun.
In a quiescent condition of the apparatus without connection to the spray
gun, the material valves VC1-VCn and the manifold outlet valves M1-Mn are
closed, the hoses H1-Hn are coupled with their associated material return
lines through the couplers 106, and the valves VC1'-VCn' are in a
condition such that the ports a, b and d are connected. To this end, for
manual spray paint operation each material supply has an associated,
relatively inexpensive pump for moving material from the supply and to the
port b of its associated valve VC1'-VCn', so that for the described
condition, and as shown in FIG. 5B, each material is recirculated from its
supply container, through its associated valve VC1'-VCn' and hose H1-Hn,
and back to its supply container through the material return line. Thus,
when material is not being sprayed, it is continuously circulated to
prevent it from settling or hardening within the system.
To spray a selected color of material, the appropriate valve VC1'-VCn' is
operated to connect its ports a, b and c, the respective material valve
VC1-VCn and manifold outlet valve M1-Mn are opened and the color change
system 12 is operated as described in respect of FIG. 1 to supply material
to the manifold inlet. At the same time, the hose H1-Hn for the selected
material is disconnected from its check valve 104 and coupled with the
spray gun 108, whereupon the material may be discharged in a spray from
the gun. Note that during the time a material is being sprayed, and as
shown in FIG. 5A, a path is also established between the port c of the
respective valve VC1'-VCn' and the material return line for continuous
circulation of material in the supply container, whereby the same does not
settle. Upon completion of spraying, the hose is uncoupled from the spray
gun and recoupled with its associated check valve 104, the respective
valve VC1'-VCn' is placed in the position connecting the ports a, b and d,
and the previously opened material valve VC1-VCn and manifold outlet valve
M1-Mn are closed, whereupon the system is returned to its quiescent state
in preparation for spraying material of the next selected color. It is
understood, of course, that upon switching from spraying material of one
color to spraying material of another, the color change system 12 is
cycled as described in connection with FIG. 1, thereby preparing the
system for pumping the new material through whichever pump P1 and P2 was
cleaned during spraying of the previous material.
The invention thus provides improved embodiments of color change systems
for spray coating apparatus, which require minimum numbers of pumps for
dosing any number of differently colored coating materials. The systems
may be rapidly changed from spraying material of one color to spraying
material of another, and are economical in structure and readily adapted
to automatic operation, although the same may also advantageously be used
in manual spray paint operations.
While embodiments of the invention have been described in detail, it is
understood that various modifications and other embodiments thereof may be
devised by one skilled in the art without departing from the spirit and
scope of the invention, as defined in the appended claims.
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