Note: Descriptions are shown in the official language in which they were submitted.
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The present invention relates to a powder
sprayer with electrostatic capacity.
It is a main object of the invention to provide
a sprayer, by means of which for example colouring powder
in a simp].e and efficient manner can be electrostatically
charged, so that all the surfaces of the particles will be
completely charged~
According to the present invention, there is
provided a powder sprayer with electrostatic charging
capacity, comprising a number of charging ducts of long
extension and made of electrically non-conducting material,
said ducts being coated with electrically conducting layers
al~ong the main portion of their extension and said coated
layers being connected to conductor means outgoing from
said layers, wherehy an electrostatically charging of the
powder material tales place during the movement of the
powder material through said charging ducts after contact -
with the inner walls of the ducts, when the sprayer is in
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An example of embodiment of the invention will
be described in the following, reference being made to the
accompanying drawings, in which
Fig. 1 is a perspective view of a powder sprayer
designed according to the invention,
Fig. 2 shows the rear end of the sprayer in partly
sectional view,
Fig. 3 shows a transportation ~nd charging tube
forming part of the sprayer and a conductor connected with this
tube,
Fig. 4 shows the front end of the sprayer in a partly
sectional view, and
Figs. 5 and 6 show khe rear end and front end res-
pectively of the sprayer in a partly sectional view according to
another example of embodiment.
A powder sprayer 1 designed according to the inven-
tion is, as mentioned above, especially adapted for use in connec- -
tion with powder spraying, the sprayer then preferably being
supported and operated by a painting robot. The sprayer- 1 comp-
rises substantially three components. A rear component 2 is a
connecting component~ which can be coupled together with a hose,
in which colouring powder is transported from a colour bin. The
colouring powder is transported throuyh a mid component 3 at the
same time as it is electrostaticalIy charged, and a front component
4 forms the noz21e of the sprayPr. The mid component 3 comprises
a tube 5 preferably made of plastic material. A core of a number
of tubes 6 of long extension but of smaller dimension and heli-
cally twisted together are enclosed in said tube 5. Also these
small tubes 6 are preferably made of plastics or some other non-
conducting material. A layer of metal 7 or any other conducting
material surrounds each one of these charging tubes 6 r as is
evident from Fig. 3. At the rear end of the charging tubes 6,
as seen in the direction of transportatiGn, there is a conductor
8 connected to said ~etal layer 7, by way of example by means of
a soldered joint 9. These conductors 8 converge and ~lend into a
common conductor 10/ which is led through an opening of the outex
tube 5 to the outside of the tube and can be grounded or connected
to a power source. Each one of the terminal ends of the charging
tubes 6 are introduced into a circular core, a rear core 11 and
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a front core 12 respectively. These cores 11, 12 along their
periphery exhibit a number of through openings 13/ which are
interspaced in a ringshaped arrangement and adapt~d to the
respective charging tubes 60 A cone 14 is provided in the centre
of the rear core 11 and points in a direction against the direc-
tion of ~ransportation, said cone functioning as an atomizer for
the powder rushing in. The rear end of the outer tube 5 supports
a sleeve 15, which at the one of its ends pointing away from the
tube 5 is provided with connections 16 for coupling together the
colour sprayer 1 and a hose, in which colouring powder is trans-
ported from a colour hopper~ The nozzle 4 is attached to the
opposite end of the ~ube. This nozzle component 4 comprises a
spray nozzle 17, a connecting tube 18 and a throttle sleeve 19.
The throttle sleeve 19 is with its rear end by means of a coup-
ling sleeve 20 connected with the charging tubes 6 and surrounds
the front end of the outer tube 5 and exhibits a conically taper-
ing through-passage 21 extending in direction away from said tube,
in which passage the charged powder is guided towards the central
axis of the sprayer 1 and the nozzle 17. The connecting tube 18
is with its rear end introduced into and held by the throttle
sleeve 19. A connecting ring 22 is threaded onto the tube 18 at ~
its front end, and said ring 22 in its turn supports said sprayer
nozzle 17. The connecting ring 22 i5 traversed by an axial duct
23, which at its reax end is connected with a hose 24 for the
supply of gas, by way of example air. rrhe nozzle 17 comprises
a sleeve 25, which at its front end supports an end wall 26,
which is provided with an opening 27 in central position. This
opening 27 exhibits a chamfered edge 27A on its outside and a
stepped shoulder 27B on its inside. The front end of a diffuser
28 is fitted into this stepped shoulder 27B, said diffuser exhibit-
ing the form of a tube made of porous permeable material trans-
mitting the air, by way of example manufactured in a sintering
process. The rear end of the diffuser 28 is threaded into the
connecting ring 22 and bears against the front end of the connect-
ing tube 18. Gas, that is introduced at an overpressure through
the duct 23 of the connecting ring, flows into the chamber 29
formed between the nozzle 17 and the diffuser 28, whereafter it
is subsequently spread through the small openings existing in the
porous material, of which the diffuser is made, before it is
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flowing into the front portion of the throug~-duct 30 of the
nozzle 4. During this phase an overpressure is created in the
front portion of the nozzle, the powder and the gas current
being compressed in order to expand and form a mist, when the
mixture emerges out of the nozzle 17. By variation of this over-
pressure the spreading of the powder can be regulated.
The function of the colour sprayer described
above will now be described more in detail. The sprayer 1, as
mentioned above, is with its rear end 16 by means of a hose
connected with a colour hopper. The colour powder is by means
of an air stream transported through the rear portion 2 of the
sprayer 1 and by means of the cone 14 spread in outwards direc-
tion, so that it flows in through the openings 13 of the core 11
and further in through the charging tubes 6. ~s menti~ned above,
these tubes 6 are either connected with the ground or with a
power source, by way of example a high tension power source,
by means of the conductors 8, 10. On account of the helical
form of the charging tu~es 6 the powder whirls around in them
during the transportation, and all sides of the particles will
arrive in contact with the walls of the tube. When emerging out
of these charging tubes 6 the powder is thoroughly charged.
After emerging from these tubes 6 the flow of powder is throttled
by the throttling component 19 and is led through the connecting
tube 18 to the spreading nozzle 17 through the flow duct 30. As
has already been described, the powder is m~ixed with the air
flowing in through the duct 24 and the diffuser 28 and is comp-
ressed in order to expand when flowing out of the orifice of the
nozzle 27, as has been described above. The powder will then be
spread in the form of a mist~ and on account of its electrostatic
charge it will find a way to the object, which shall be painted,
and stick to the same. Also parts of the painting object, which
are difficult to reach, will be covered with colour.
The powder sprayer, which is shown in Figs. 5 and
6, is of similar design as the sprayer described above, and such
parts as are common for the two examples of embodiment are indi-
cated with the same reference numbers.
As distinguished from the earlier described sprayer
the sprayer according to Figs. S and 6 is provided with charging
ducts 6' of irregular curvature instead of helically curved ducts.
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Each duct 6' extends in a number of different planes, as is
for example shown in the Figs. 5 and 6.
The function of this powder sprayer is the same
as the function of the sprayer described above. The powder~
which is led through the sprayer and its charging ducts 6',
will be effectively charged during the movement of the powder
through said charging ducts 6' after whirling around and contact-
ing the innex walls of said ducts 6'.
The invention is not limited to the embodiments
described above and illustrated in the drawings, but can be
varied as to its details within the scope of the following claims.
