Note: Descriptions are shown in the official language in which they were submitted.
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P.7305
Sulzer Metco AG, CH-5610 Wohlen, Switzerland
An apparatus for the surface working of a workpiece as well as the use of
the apparatus for the blasting of bore walls
The invention relates to an apparatus for the surface working of a work-
piece by blasting with an abrasive blasting material as well as to the use of
the apparatus for the blasting of bore walls in accordance with the pream-
ble of the independent claim of the respective category.
For the pre-treatment of workpieces, in particular for the pre-treatment
with thermal coating, surfaces of components are frequently activated by
blasting, for example with aluminium materials. This ensures, among
other things, a sufficient gripping engagement of a coating material with
the substrate. However, blasting, is also frequently used as a suitable
method for the roughening and even for the compacting of surface layers
(introduction of internal stress by peening) of surfaces, such as, for exam-
ple, with classical sandblasting, with - in addition to conventional sand -
also other materials such as ceramic powders, special metallic powders or
other powders or fine dusts being used as the blasting material. The
method of blasting is, among other things, widespread and particularly
suitable for the working of bore walls and tube walls, since the surfaces of
such internal walls can often only be worked with difficulty using other
methods.
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For this reason, a whole series of apparatuses and methods are well-
known in the prior art for the working of surfaces of workpieces by blast-
ing. For instance, an apparatus known as a RotaBlast and a correspond-
ing method are described in EP 0 727 282 B1, for example, in which a
blasting material is stored in a storage container of sufficient size and is
supplied from there to a suitable metering device which is arranged di-
rectly beneath the storage container. After having been metered by the
metering device, the blasting material is then transported with the help of
an injector with compressed air into a blasting means transport hose
flanged directly to the injector and also known as a blasting means pres-
sure hose. The blasting material is transported by the blasting means
transport hose, which is made up of special rubber material, possibly with
an India rubber liner, to the RotaBlast apparatus for the blasting of a
workpiece.
Currently, high wear phenomena occur at the blasting means transport
hoses. The hoses, which are mostly made, as already mentioned, from a
plastic or rubber, wear out in particular at a spacing of approximately
100 mm to 150 mm from the outlet of the blasting material from the
injector. Strong flow turbulence occurs in this region which wears the
hose material abrasively even more from the inside in this region due to
the blasting means transported in the airflow. This results in the hoses
being so heavily worn even after a very short operating time that the op-
eration of the plant has to be stopped and the worn blasting means trans-
port hoses have to be replaced. A further disadvantage of the overpressure
principle briefly described above consists of the fact that the transport of
the blasting material requires compressed air which is especially prepared
with the aid of the injector and which has to be made available by the
user. This requires appropriate additional plants with the corresponding
financial and labour effort.
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It is therefore the object of the invention to provide an improved apparatus
for the surface treatment of a workpiece by blasting with an abrasive
blasting material which avoids the disadvantages of known apparatuses
from the prior art.
The subject matters of the invention satisfying these objects are character-
ized by the features of the independent claim of the respective category.
The dependent claims relate to especially advantageous embodiments of
the invention.
In accordance with the invention, an apparatus for the surface working of
a workpiece by blasting with an abrasive blasting material is thus pro-
posed including a storage container for the blasting material, a metering
device and a device for blasting. The device for blasting has a blasting
material feed with an inlet and an outlet for the blasting material, with the
blasting material being able to be fed to a jet region through the blasting
material feed and the outlet. The device for blasting furthermore includes
a pressure supply for the deflection by means of a pressure medium of a
blasting material flow emerging from the outlet, with control means being
provided at the inlet of the blasting means feed for the introduction of the
blasting material flow.
Since, in the apparatus in accordance with the invention for the blasting
with an abrasive blasting material, the control means - which can in
particular include, as will be explained in more detail further below, a
metering device or an injector nozzle - are arranged directly at the inlet of
the blasting means feed of the device for blasting, the blasting material is
no longer fed to the blasting material feed, as is known from the prior art,
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by means of overpressure through a blasting means pressure hose,
whereby the known problems with premature wear phenomena of the
blasting means pressure hoses are avoided.
The device for the blasting of the apparatus in accordance with the inven-
tion is known per se from the prior art and substantially includes a blast-
ing material feed, for example in the form of a tube, which has an inlet
and an outlet, with an abrasively acting blasting material being able to be
fed to the inlet which can be discharged again through the outlet of the
blasting material feed in the form of a blasting material flow in a jet re-
gion. The blasting material feed is preferably, but not necessarily, ar-
ranged vertically, that is parallel, to the action of gravity such that the
blasting material can reach the outlet of the blasting material feed in a
blasting material flow from the inlet solely by the action of gravity.
The blasting material flow emerging from the outlet is deflected by means
of a pressure medium, which can be fed to the jet region via a pressure
supply, onto a surface of a workpiece to be worked, whereby the surface of
the workpiece is worked. The pressure medium for the deflection of the
blasting material flow can include, for example, a fluid such as com-
pressed air, or also a suitable liquid or another suitable medium.
The blasting material can be fed to the control means provided at the inlet
of the blasting material feed of the device for blasting from a storage con-
tamer for the blasting material, with the control means being suitable for
the introduction of the blasting material flow into the inlet of the blasting
material supply. For the controlled feed of blasting material from the
storage container to the blasting material feed, the apparatus in accor-
dance with the invention includes a metering device known per se
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In a preferred embodiment of an apparatus in accordance with the inven-
tion, the control means for the introduction of the blasting material flow
includes the metering device. This means that the metering device is
arranged directly at the inlet of the blasting material feed. The storage
5 container for the blasting material can be arranged in a first embodiment
directly at the metering device such that no feed line is provided for the
feed of blasting material from the storage container to the metering device.
Alternatively, in a second embodiment, the control device designed as a
metering device can be connected to the storage container via a feed line.
Auxiliary means can be provided which support the feed of the blasting
material from the storage container to the control means. In particular,
the blasting material can be fed from the storage container to the control
means by means of a transport medium, for example by air. It is naturally
also possible that blasting material is supplied from a storage container to
a plurality of devices for blasting.
In another important embodiment for practice, the control means for the
injection of the blasting material flow include an injector nozzle known per
se, with the injector nozzle being connected to the metering device via a
connection line such that blasting material can be fed from the storage
container to the injector nozzle via the metering device and the connection
line. The metering device can in particular be arranged directly at the
storage container. The blasting material is introduced by the injector
nozzle via the inlet of the blasting material feed directly into the blasting
material feed under a pre-settable pressure as a blasting material flow.
The injector nozzle known per se, which can be operated with compressed
air, produces an underpressure in the connection line, whereby the blast-
ing material is sucked to the injector nozzle. Hardly any turbulence is
hereby created in an inlet region of the connection line, which is prefera-
bly made of a plastic, for example rubber, so that the connection line is
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not exposed to any excessive abrasive wear like the blasting means pres-
sure hoses known from the prior art.
The connection line and/or the feed line is/are lined at its/their inner
wall, preferably with boron carbide. Boron carbide is a known and suitable
material for the reduction of wear, in particular on the use of abrasively
acting materials, and is therefore also preferably used for the injector
nozzle.
In a variant important for practice, the injector nozzle is preferably made
up of boron carbide and is exchangeably connected to the blasting mate-
rial feed and/or to the connection line. In particular the transition to the
connection line and/or to the blasting material feed is designed by the use
of a transition nozzle such that, where possible, no turbulence occurs in
the flow of the blasting material, whereby the wear of the components
involved can be substantially reduced.
In a particularly preferred embodiment, the pressure supply includes an
endpiece which deflects the pressure medium in the jet region and has an
opening from which the pressure medium is discharged into the jet region.
The pressure supply is rotatably arranged about a longitudinal axis of the
blast material feed, with the opening of the endpiece of the pressure sup-
ply being arranged and alignable such that the blasting material flow
emerging from the outlet of the blasting material feed can be deflected
onto a workpiece to be blasted. The pressure supply can be rotatable by a
rotary drive about the blasting material feed. An electric motor, a pneu-
matic or a hydraulic drive, or another suitable drive can be used, for
example, as the rotary drive.
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The apparatus in accordance with the invention preferably includes a
flowmeter for the monitoring and measurement of a mass flow of the
blasting material. The flowmeter can, for example, be provided in the
connection line or in the feed line or at any other suitable position at the
apparatus in accordance with the invention.
The apparatus in accordance with the invention can in particular include
a freely programmable control unit for the control and/or regulation of the
metering device and/or of the control means for the introduction of the
blasting material flow and/or of the rotary drive. In a variant important for
practice, regulation means can be provided, for example in the form of
suitable valves, with which the mass flow can be controlled and/or regu-
lated by the control unit in dependence on pre-settable operating parame-
ters. The flowmeter is preferably connected by signal to the control unit for
the transfer of actual data of the mass flow so that, for example, the ac-
tual mass flow can be used for the control and/or regulation.
In accordance with the invention, the use of the apparatus is furthermore
used for the surface working of a workpiece by blasting with an abrasive
blasting material, for the blasting of bore walls or tube walls, in particular
of cylinders of reciprocating internal combustion engines.
The invention will be described in more detail in the following with refer-
ence to the schematic drawing. There are shown:
Fig. 1 an apparatus in accordance with the invention with a storage
container, a metering device and a device for blasting;
Fig. 2 a further embodiment of an apparatus in accordance with the
invention.
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Fig. 1 shows, in a schematic representation, an apparatus in accordance
with the invention for the surface working of a workpiece by blasting with
an abrasive blasting material, which apparatus is designated as a whole
by the reference numeral 1 in the following.
The apparatus 1 in accordance with the invention includes a storage
container 4 for a blasting material 3, a metering device 5 and a device for
blasting 6. The device for blasting 6 has a blasting material feed 7 with an
inlet 8 and an outlet 9 for the blasting material 3, with the blasting mate-
rial 3 being able to be fed to a jet region 10 through the blasting material
feed 7 and the outlet 9. The device for blasting 6 furthermore includes a
pressure supply 11 for the deflection of a blasting material flow 12 emerg-
ing from the outlet 9 by means of a pressure medium (13), with control
means 14 being provided at the inlet 8 of the blasting material feed 7 for
the introduction of the blasting material flow 12.
The device for blasting 6 shown in Fig. 1 is known per se from the prior
art, as is the metering device. The blasting material feed 7 is designed in
the form of a straight tube 7 which is arranged in accordance with the
representation in the embodiment shown in Fig. 1 in a perpendicular
manner, that is with its longitudinal axis L parallel to the effective direc-
tion of gravity. The control means 14 for the introduction of the blasting
material flow 12 are here designed as a metering device 5. This means
that the metering device 5 is arranged directly at the inlet 8 of the blasting
material feed 7. The storage container 4 for the blasting material 3 in the
embodiment shown here is arranged directly at the metering device 5 such
that no feed line to the feed of the blasting material 3 is provided from the
storage container 4 to the metering device 5. The transport of the blasting
material 3 into the blasting material feed 7 takes place solely by gravity.
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The same applies to the transport of the blasting material 3 in the from of
the blasting material flow 12 from the inlet 8 to the outlet 9 of the blasting
material feed 7.
The blasting material flow 12 emerging from the outlet 9 can be deflected
by means of the pressure medium (13), which can be supplied to the jet
region IO via the pressure supply 11, onto a surface of a workpiece 2 to be
worked, whereby the surface of the workpiece 2, for example the inner
wall of a cylinder of a reciprocating combustion engine, is worked. The
pressure medium ( 13) for the deflection of the blasting material flow 12
can include, for example a fluid ( 13) such as compressed air, or also a
suitable liquid ( I3) or another suitable medium ( 13) .
The pressure supply 11 includes, in the jet region 10, an endpiece 71
which deflects the pressure medium ( 13) and has an opening 72 from
which the pressure medium ( 13) is discharged into the jet region 10. The
pressure supply 11 is rotatably arranged and is alignable about the longi-
tudinal axis L of the blasting material feed 7, with the opening 72 of the
endpiece 71 of the pressure supply 11 being arranged and alignable such
that the blasting material flow 12 emerging from the outlet 9 of the blast-
ing material feed 7 can be deflected onto the workpiece 2 to be blasted. In
the variant shown here, the pressure supply 11 can be rotated about the
blasting material feed 7 by a rotary drive 17, with the rotary drive prefera-
bly being designed as an electric motor or as a pneumatic drive or as a
hydraulic drive.
The apparatus 1 in accordance with the invention can in particular have a
sensor not shown in Fig. 1, in particular a flowmeter ( 15) for the meas-
urement of a mass flow of the blasting material, which is provided with a
freely programmable control unit, likewise not shown, for the control
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and/or regulation of the metering device 5 and/or of the control means 14
for the introduction of the blasting material flow 12 and/or of the rotary
drive 17.
5 In Fig. 2, a further embodiment of an apparatus in accordance with the
invention is shown schematically. In this embodiment, which is important
for practice, the control means 14 for the introduction of the blasting
material flow 12 include an injector nozzle 141 known per se, with the
injector nozzle 141 being connected to the metering device 5 via a connec-
10 tion line 16 such that blasting material 3 can be fed from the storage
container 4 to the injector nozzle 141 via the metering unit 5 and the
connection line 16. The connection line 16 includes a flowmeter 15 for the
measurement of a mass flow of the blasting material 3 which is connected
by signal to a control unit (not shown). The metering device 5 is in par-
ticular arranged directly at the storage container 4. The blasting material
3 is introduced directly into the blasting material feed 7 by the injector
nozzle 141 as a blasting material flow 12 via the inlet 8 of the blasting
material feed 7 at a pre-settable pressure. The injector nozzle 141 known
per se, which can be operated with compressed air, produces an under-
pressure in the connection line 16, whereby the blasting material 3 is
sucked to the injector nozzle 141. Hardly any turbulence hereby occurs in
an inlet region of the connection line 16, which is preferably made up of a
plastic, for example rubber, such that the connection line 19 is not ex-
posed to any excessive abrasive wear like the blasting means pressure
hoses known from the prior art.
