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Патент USA US3075716

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Jan. 29, 1963
-
M. A. R. POINT
3,075,706
GUN FOR ATOMIZATION AND ELECTROSTATIC SPRAYING OF MATERIALS
Filed May 9, 1960
~ 5&5"
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Inventor
niteri tats
h?lh?hh
te
Patented Jan. 29, 1%53
1
2
member 16, the paint becomes deposited thereon. The
3,675,706‘
GUN FUR ATGMEZATKGN AND ELECTROSTATIC
SPRAYL‘JG 91*“ MATERIALS
Marcel Auguste Roger Point, Grenoble, France, assignor
to Soeiete Anonyrne de Machines Electrostatiques,
Grenoble, France, a French body corporate
Filed May 9, 1960, Ser. No. 27,875
Ciaims priority, appiication France May 20, 1959
7 tllairns. (Cl. 239-15)
head member 16, connected to the source of high tension
G, by the cable 5, produces a second atomization of the
paint which is then directed towards the object 17 to be
covered.
It will be seen that the potential of the central head
member 4 is determined by the resistance of the column
of paint. Thus with an electrically conducting paint this
potential can be approximately earth potential. It is
pointed out that this potential only exists during operation
The present invention relates to guns, particularly for
of the gun, that is when the head member 4 is electrically
hand use, for the atomization and electrostatic spraying
connected to the column of paint being supplied to it,
of liquids, especially for spraying of materials which are
and that this head member is electrically connected to
electrically conductive, such as metallised paints or water
the outer head member 16 by the atomized particles of
paints. The invention has for its object to provide an 15 material which are projected by the head member 4 on
improved gun having a head by means of which the paint
to the head member 16.
is submitted to a double atomization due to two cooper
While a particular embodiment has been described it
ating members.
will be understood that various modi?cations may be
In order that the invention may be more clearly un
made without departing from the scope of the invention
derstood, an embodiment thereof will now be described 20 as de?ned by the appended claims.
by way of example with reference to the accompanying
Thus, although in the embodiment shown in the draw
drawing which shows an axial longitudinal section of a
ing the two head members 4- and 16 rotate simultaneously
gun according to the invention.
in the same direction and at the same speed, in a modi
Referring to the drawing, the gun comprises a handle 1
?cation the two head members can rotate in opposite
to which is ?xed in any appropriate manner an elon
directions and, if desired, at di?ferent speeds. It su?ices
gated body 2 of insulating material. Into the handle ex
mechanically to connect the two head members by means
tend (a) a pipe 3 for the supply of paint under a pressure
of pinions and appropriate gear wheels, subject to the
which has its outlet in a central rotating head member
condition that these gears maintain the electric insulation
4 of any convenient type having an atomization edge 4a,
of the two head members in the same manner as the part
which head member can be of conducting, high resistivity 30 15. Each head member can alternatively be driven by
or insulating material; (b) a high tension cable 5 connect
a separate motor if this is advantageous in any particular
ed, preferably through an electric protective resistance 6,
to an electrode 7 which is ?xed at the end of an exten
sion Zn on the body 2; (c) a low tension cable 8 for
supplying current to an electric motor 9 which is ?xed
to the gun.
The handle also comprises a trigger it}, operable by
application.
Further, instead of being constructed for hand use,
the gun according to this invention may be constructed
for ?xing in position in a paint spraying machine.
I claim:
1. A spray gun for centrifugally and electrostatically
the user, which is associated with a rod 11 by means of
atomizing and spraying a liquid coating material on to an
which it can control a valve 12 connected in the paint
object to be coated, said gun comprising a head having
supply pipe 3 and a switch 13 connected in the cable 8 40 an inner rotatable electrically conducting member for
in the circuit of the motor 9*.
effecting an initial atomization of the coating material
The motor 9 drives the central head member 4 by
by means of centrifugal force and including an edge by
means of an insulating shaft 14 having an extension rod
means of which the initially atomized coating material
14a which passes through the end wall of the body 2
leaves said inner member, an outer electrostatic atomiz
and is ?xed to the hub portion 41) of the central head 45 ing and spraying member to which the coating material
member 4. An insulating support 15 is ?xed to the outer
leaving the edge of the inner member is attracted and
surface of the head member 4 in a manner such that it
including an edge which is radially spaced from the edge
does not cover the tapering atomizing edge 4a of the
of the inner rotatable member and from which the
head member. To the outer surface of the support 15 is
eleotrostatically atomized particles of coating material
?xed the internal surface of an outer electrostatic head 59 are directed on to the object to be spray-coated, an insu
member 16, care again being taken that the tapering
atomizing edge 16a of the head member remains free.
The head member 16 is made of metal or semi-conducting
high resistivity material.
lating member for coaxially and mechanically intercon
necting said inner and said outer members, means for
applying a direct high potential to said outer electrostatic
member, means for feeding liquid covering material to
The radial dimensions of the support 15 and of the 65 said inner member, and an electric motor ?xed to said
outer head member 16 are such that the rear edge of
gun for rotating at least the inner member of said head.
the head member 16 faces and is spaced a very short
2. A gun according to claim 1, wherein the outer elec
distance away from the electrode 7. If desired, in a
trostatic member comprises an active atomizing and
modi?cation, the electrode ‘7 can be constituted as a
spraying edge situated in front of the plane of the edge
spring-pressed contact adapted to engage the head 16. 60 of the inner rotating member and also in front of the
The motor 9 rotates the two head members 4 and 16
simultaneously, the paint being delivered to the central
head member 4 and the high tension being applied to the
outer head member 16.
The paint may be delivered
into an annular groove at the rear of the head member 4
plane containing said insulating member.
3. A spray gun for centrifugally and electrostatically
atomizing and spraying a liquid coating material on to
an object to be coated, said gun comprising a head hav
ing an inner rotatable electrically conducting member of
generally cylindrical shape for effecting an initial atom
ization of the coating material by means of centrifugal
force and including an edge by means of which the initial
and pass to the front part of this head member through
apertures do in the hub 4b of the head member 4.
The operation of the device is as follows:
Paint supplied to the central head member 4 is submit
ly atomized coating material leaves said inner member,
.ted to a ?rst atomization (or distribution) due to the 70 an outer generally cylindrically electrostatic atomizing
centrifugal force and the electric ?eld existing between
and spraying member to which the coating material leav~
the two head members. Attracted by the outer head
ing the edge of the inner member is attracted and in
eluding an edge which is radially spaced from the edge
of the inner rotatable member and from which the elec
ing a direct high potential to said outer electrostatic
member, means for feeding liquid coating material to said
trostatically atomized particles of coating material are
inner member, and an electric motor ?xed to said gun
directed on to theobject to be spray coated, an insulating
for rotating said head and wherein said edge of the outer
member for coaxially and mechanically interconnecting
electrostatic atomizing and spraying member is situated
said inner and said outer members, means for applying a
in front of the plane of the edge of the inner rotatable
member and also in front of the plane containing said in
direct high potential to said outer electrostatic member,
means for feeding liquid coating material to said inner
member, and an electric motor ?xed to said gun for
sulating member.
5. A gun as claimed in claim 1 wherein the outer mern~
rotating at least the inner member of said head.
10 her is connected to the source of high potential by means
4. A spray gun for centrifugally and electrostatically
of a metallic electrode supported from the insulating
atomizing and spraying a liquid coating material on to
body of the gun and sufficiently near to the rear surface
an object to be coated, said gun comprising a head hav
of the said outer member to permit sparks to jump be
ing an inner rotatable electrically conducting member of
tween it and said outer member.
.
generally cylindrical shape for effecting an initial atomiza 15 6. A gun as claimed in claim 1, wherein the outer
tion of the coating material by means of centrifugal force
member is made of an electrically conducting material.
and including an edge by means of which the initially
7. A gun as claimed in claim 1, wherein the outer
atomized coating material leaves said inner member, an
member is made of an electrically high resistivity material.
outer generally cylindrical electrostatic atomizing and
spraying member to which the coating material leaving 20
the edge of the inner member is attracted and including
an edge which is radially spaced from the edge of the
inner rotatable member and from which the electro
statically atomized particles of coating material are
directed on to the object to be spray coated, an insulat 25
ing member for coaxially and mechanically interconnect
' ing said inner and said outer members, means for apply
References Cited in the ?le of this patent
UNITED STATES PATENTS
2,658,009
2,781,279
2,809,902
2,922,584
2,926,106
Ransburg _____________ __ Nov. 3,
Miller ______________ __ Feb. 12,
Ransburg ____________ __ Oct. 15,
Slatkin ______ _________ __ Jan. 26,
Gauthier ____________ __ Feb. 23,
1953
1957
1957
1960
1960
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