LIQUID JET SURFACE TREATMENT

TRAITEMENT DE SURFACE PAR JET DE LIQUIDE

English Abstract

ABSTRACT OF THE DISCLOSURE
In a process and apparatus for treating surfaces
by means of a jet of liquid impinging on the latter at high
velocity and with which, in particular, scouring or polishing
solid particles, such as steel granules, corundum, sand,
chalk or the like are admixed, the liquid jet is, after it
has impinged on a surface to be treated, at least once
returned to a surface to be treated for the purpose of exploiting
the residual kinetic energy of the liquid. In a preferred
form of the invention, the jet impinges on the surface at an
angle of between 30° and 80° and is, after reflection from said
surface, returned to the latter to impinge thereon at an angle
of between 40° and 90°. In a particular embodiment of the
invention, a sheet metal strip is guided along a loop and
the jet impinges on a concave region within said loop. The
reflected jet may also, after being reflected from the surface
of a first workpiece, be caused to impinge on the surface
of a second workpiece moving transversely to the first workpiece.

Claims

THE EMBODIMENTS OF THE INVENTION IN WHICH AN EXCLUSIVE
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:
1. A process for treating a surface wherein a jet of liquid with
which scouring and polishing particles are admixed emerges from a nozzle at
a gauge pressure of 200 to 600 bar and is directed to impinge on a portion
of said surface at an angle of between 30 and 80° and, after the jet has
impinged on said portion is at least once returned to a second portion of
said surface displaced in the direction of the jet to the first portion for
treatment of said second portion so that the residual kinetic energy is
utilised.
2. A process according to claim 1 wherein a sheet strip is guided
along a loop and said jet impinges on a concave region of said strip within
said loop so that the reflected jet impinges along a polygon line on portions
of said concave region displaced in the direction of the jet.
3. A process according to claim 1 wherein said jet is reflected and
diverted by means of at least one further jet emerging from a second nozzle
and impinging on the reflected jet, and again impinging on said surface.
4. A process according to claim 3 wherein the cross-section of said
second nozzle is C-shaped.
5. A process according to any one of the claims 1 to 3 wherein said
particles are steel granules and/or corundum and/or sand and/or chalk.

Description

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Ihe invention relates to a process or treating surfaces by means
of a jet of liquid impingin~ on the surface tc be treated at high velocity
and with which~ in particular, scouring or polishing solid particles, such
as steel granules, corundum, sand~ chalk or the like, are admixed. This
process serves the purpose of de-rusting~ de-scaling and cleaning of iron
and steel and also of the surface treatment of plastics. In this process
liquids, particularly water, aTe-sprayed under very high pressure, e~g. of
200 to 600 atmospheres, fTom steel nozzles on to the surface to be treated.
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In the nozzle polishing or scouring solid particles are admixed with the
~`~r 10 liquid jet in a dry OT wet state. The process is applica~le with advantage
to the treatment of sheet metal, rolling profiles, tubes, wires and castings,
and moreover also to the matting of plastics surfaces. The liquid jet
~, impinging at high velocity on the surface to be treated teaTs dirt, scale
and rust particles, oils adhering thereto and paint off this surface. In
order to enhance the abrasive effect of the liquid jet, scouring or polish-
ing solid particles are admixed therewith. When the liquid jet impinges on
: the surface to be treated, these solid particles pass through the liquid
film and thus become effective.
In the known process the energy consumption is relatively large.
The object of the present invention is to pTovide a process, with the aid of
which improved energy utilisation in the course of the above-described
process is made possible.
Accordingly, the method of the invention consists of a process
for treating a surface wherein a jet of liquid with which scouring and
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polishing paTticles are admixed emerges from a nozzle at a gauge pressure of
200 to 600 bar and is directed to impinge on a portion of said surface at an
angle of between 30 and 80 and~ after the jet has impinged on said portion
- is at least once returned to a second portion of said suTface displaced in the
direction of the jet to the first portion for treatment of said second
portion so that the residual kinetic energ~ is utilised.
For the purpose of treating the surface of a sheet metal strip or
a roller profile, the liquid jet is preferably directed in a direction counter
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to the direction of movement of the material to be treated.
`~ In the following detaïled description, preferred forms of the
invention and the apparatus therefor will be explained in grea~er detail ~ -
with reference to the drawings.
In the drawings:
Figure 1 is a perspective view of an apparatus for treating a sur-
face wherein a nozzle for diverting a jet of liquid is employed;
Figure 2 is a diagrammatic representation of apparatus for treating
sheet metal strips; and
; 10 Figure 3 is a perspect;ve view of appaTatuS for treating two
objects simultaneously.
. As shown in Figures 1, 2 and 3, a liquid jet ~ is sprayed at high
... . : . .
velocity on to the surface 1 to be treated of a sheet metal strip 2 by means `
of a nozzle 3. Scouring and poiishing particles such as steel granules,
corundum, sand~ or chalk are admixed with the liquid jet 4. The jet 4
emerges from the nozzle at a guage pressure of 200 to 600 bar and is directed
to initially impinge on the surface 1 at an angle of between 30 and 80.
Figure 1 shows a perspective view of apparatus in which the re- -
flected jet medium 4 is diverted by a jet 28 from an additional nozzle 25. .
After being discharged from the nozzle 3, which in this embodiment is of
elongate cross-section, the jet medium 4 impinges on a first portion of the
surface 1. The reflected jet is discharged upwardly to the left ~Figure 1),
is intersected by the jet 28 from the additional nozzle 25, thereby changing i
its direction and impinges on a second portion of the surface 1 in the for~
of a jet 9. This second portion is displaced in the direc~ion of the jet to
the first portion.
The jet 28 from the additional nozzle 25 is preferably a liquid
jet without solid particles, the same liquid being used as that for the
nozzle 3. The jet 28 may, however, also be a compressed air jet or a jet
of a second liquid, it may also contain solid particles.
In the embodiment according to Figure 1, the cross-section of the
additional nozzle 25 is C-shaped. This is intended to have the effect of

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the jet 4, which diverges after its impact on the surface 1, being reunited.
The additional nozzle generally subtends a different angle to the surface 1
from that of the nozzle 3. The desired inclination may for example be
determined by a setting device 26, 27.
In Figure 2 the treatment of a sheet metal strip 2 is shown, which
is conducted in the form of a loop by means of rollers 37, 38 and other
`` devices (not shown) so that a concave inner space is formed. ~he jet medium
~: 4 is sprayed into this inner space with the aid of the nozzle 3. The jet
medium impinges on the surface to be treated in such a way that, after
- 10 reflection, it again impinges on the surface to be treated. After several
reflections the jet medium flows along the surface and flows away below the
` roller 37. The flow along the concavely curved area of the sheet metal
strip has the effect that the heavier solid particles are accelerated by a
centrifugal effect on to the surface to be treated and flow therealong.
For the purpose of descaling a sheet steel strip the loop formation may
simultaneously also serve the purpose of tearing open the scale layers on
the sheet metal strip.
~ In the apparatus according to Figure 3 the jet 9 which is dischargsd
f from the nozzle 3 and reflected by the surface 1 of the first workpiece 2
impinges on a second workpiece 42 and is thrown back by its surface 41 on to
the first workpiece 2. In this way two workpieces may be treated simul-
` taneously and very efficiently by utilising the residual kinetic energy in
; the jet medium. The second workpiece 42 is preferably moved above the point
of impact of the jet medium 4 transversely to the direction of movement of
the first workpiece.
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