WO2003022525A2

WO2003022525A2 - Blasting method and device

Info

Publication number: WO2003022525A2
Application number: PCT/EP2002/010128
Authority: WO
Inventors: Jens Werner Kipp
Original assignee: Jens Werner Kipp
Priority date: 2001-09-11
Filing date: 2002-09-10
Publication date: 2003-03-20
Also published as: WO2003022525A3

Abstract

The invention relates to a blasting method and device for cleaning surfaces, in which an additional blasting medium from a pressurised source is fed into a stream of blasting medium, which carries an abrasive blasting agent, with the aid of an adapter (16). The invention is characterised in that said feeding of additional blasting agent takes place directly upstream of a blasting nozzle (18), which has a narrowing (62) and that both the pressure and volumetric output for the blasting media are matched with one another in such a way, that the blasting medium achieves at least approximately the speed of sound at the narrowing (62) of the blasting nozzle (18).

Description

BLASTING METHOD AND DEVICE

The invention relates to a blasting method for cleaning surfaces, in which an additional blasting medium is fed from a pressure source into a stream of a blasting medium which carries an abrasive blasting medium, and an apparatus for carrying out the method.

Blasting devices are used to clean surfaces using a mostly gaseous blasting medium, to which an abrasive blasting agent such as sand or the like can be added. It is also known to use dry ice or dry snow as a blasting agent. This has the advantage that no expensive precautions need to be taken to dispose of the abrasive, since the abrasive evaporates after use. In addition, due to the low temperature of the blasting medium of approximately -78 ° C., the layers to be cleaned become brittle and subsequent effects, such as evaporation of the dry ice particles that have penetrated into the layer to be cleaned, result in an intensive cleaning effect.

EP 1 035 947 B1 describes blasting methods and devices which are used for cleaning the inside of pipes. In one of these devices, a Laval nozzle is provided as the jet nozzle, which is moved through the pipe to be cleaned. In the Laval nozzle, the blasting medium is accelerated to almost the speed of sound or to supersonic speed. The emerging jet is conically expanded by a deflecting body arranged downstream of the Laval nozzle, so that it strikes the surrounding pipe wall. In another method described in this document, only one deflector is moved through the interior of the tube, and the blasting medium, to which dry ice is added as the blasting medium, is fed into the tube via an adapter attached to the tube end and passed through the tube. The adapter also offers the possibility of supplying an additional blasting medium via a side connection, which is transported into the adapter with the aid of an additional blasting medium supplied by a pressure source. In cases where the abrasive effect of dry ice is not sufficient, the cleaning effect should be increased by adding the additional blasting agent, for example sand or granulate.

In terms of quick and intensive cleaning of larger areas, it is it is desirable that the jet emitted by a jet nozzle be fanned out as far as possible at high speed of the jet medium, for example air. For this purpose, various nozzles are known which generate a fan-like or conically widened jet. Conventional blasting systems in which the blasting medium (compressed air) is mixed with the blasting medium, in particular dry ice, can only produce limited air outputs, and the hoses used to supply the blasting medium and the blasting medium to the blasting nozzle can only absorb limited air outputs. This limitation limits the performance of the usual jet nozzles. In addition, it has proven difficult to produce a fan-shaped beam with the aid of known beam devices, which beam has a high output and is sufficiently fanned out. The use of mechanical means for widening the jet has the disadvantage that it becomes one, particularly in the case of dry ice. Damage to the abrasive particles, so that the cleaning effect decreases.

The object of the invention is therefore to provide a blasting method and a blasting device which allow a high blasting power and / or a wide fanning out of the blasting without causing excessive damage to the blasting medium.

This object is achieved in a method of the type mentioned at the outset in that the supply of the additional blasting medium takes place upstream of a blasting nozzle which has a constriction, and the pressure and volume outputs for the blasting media are coordinated with one another in such a way that the blasting medium is at the constriction the nozzle reaches at least approximately the speed of sound.

In this method, the supply of the additional blasting medium directly in front of the nozzle does not, at least not primarily, serve to supply a further blasting medium, but rather serves to accelerate the jet in front of and in the nozzle. This additional acceleration of the medium in front of and in the blasting nozzle enables a wide fanning out of the jet without the blasting agent being damaged.

With this method it is possible to produce very high flow velocities and air outputs in the nozzle despite the limited output of the blasting system which supplies the blasting medium mixed with the blasting medium. About that In addition, the addition of the additional blasting medium leads to the formation of turbulence, which has a favorable effect on the blasting geometry and further increases the speed and the cleaning effect. Another advantage is that the additional blasting medium is fed separately to the nozzle via a separate hose, so that overall very high air outputs are achieved. If the additional blasting medium is not itself mixed with an additional blasting medium, there are also less strict restrictions with regard to the controllable pressure and volume output when this additional blasting medium is supplied. The blasting geometry and thus the cleaning effect can be optimized by coordinating the pressure and volume outputs of the primary blasting medium supplied directly from the blasting system with blasting medium on the one hand and the additional blasting medium on the other hand.

An expedient device for carrying out the method comprises an adapter with at least a first inlet, which is connected to a blasting system and to which a primary stream of a blasting medium mixed with a blasting medium can be fed from the blasting system, and at least a second inlet, to which an additional blasting medium from a Pressure source can be supplied, as well as with an outlet, through which the primary stream and the additional blasting medium emerge, and a blasting nozzle which directly adjoins the outlet of the adapter and has a constriction.

Advantageous refinements and developments of the invention result from the subclaims.

Dry ice or dry snow is preferably used as the blasting agent in the primary stream. With the additional blasting medium, an additional blasting medium can optionally be supplied. It is also possible for the adapter to have a plurality of connections via which further blasting media and blasting media can be added.

The jet nozzle can be designed as a Laval nozzle or a Venturi nozzle. It can be designed to be rotationally symmetrical with respect to its longitudinal axis or, alternatively, can also be flattened, so that a fan-shaped expanded beam is generated. The jet nozzle is preferably arranged directly behind the adapter. She can but also be connected to the adapter via a longer line.

In one embodiment, the adapter is designed in such a way that the primary current is supplied via an inner tube which is arranged coaxially with the outlet of the adapter and which forms an annular space with the housing of the adapter, into which the second connection of the adapter opens and which coexists communicates with the outlet of the adapter. The mouth of the inner tube, which is preferably narrowed in the shape of a nozzle, is then flowed around by the additional blasting medium, so that the primary stream is accelerated effectively but gently and without damaging the blasting medium. Optionally, the annular space can also be connected to the inner tube via a ring of channels converging in the flow direction upstream of the mouth.

In an embodiment currently regarded as particularly preferred, the adapter forms at least one constriction for the flow of the additional blasting medium. This constriction can be formed at one or more of the following locations:

at the second inlet of the adapter, for example in that this inlet has a smaller cross section than the hose used to supply the additional blasting medium;

in the annular space between the inner tube and the housing wall of the adapter;

- Between the mouth of the inner tube and a narrowing of the adapter housing in the transition area between the annular space and the outlet. In this case, the cross section of the constriction can be varied by making the inner tube axially adjustable. A throttle device, for example in the form of a ball valve, is preferably arranged at the second inlet of the adapter for coordinating the pressure and volume outputs.

The state of aggregation of the abrasive or abrasives used in the method according to the invention can be solid, liquid or gaseous or a combination of these states of aggregation. It has been shown that the addition of very small amounts of water to the primary or secondary stream leads to very good cleaning results. The cleaning effect is due on the one hand to the kinetic effect. The extremely high flow Speed of the blasting medium leads to a greatly increased kinetic effect - possibly even without the addition of blasting medium. Especially when water is added - here at the same time as an additional blasting medium as well as a blasting agent - the cavitation effect of the water that occurs with the design of the adapter and the blasting nozzle described here is added.

Due to the extremely high flow velocities that can be achieved with the blasting device according to the invention, a high recoil occurs when handling the blasting device, which may make it difficult for the operating personnel to keep the blasting device in a suitable position relative to the surface to be cleaned. According to a further development of the invention, the combination of adapter and blasting nozzle is therefore mounted on a chassis designed in the manner of a hand truck, which is pushed or pulled over the surface to be cleaned and which keeps the nozzle of the blasting nozzle at a suitable distance from the surface to be cleaned , Due to the leverage effect of the chassis, the optimal angle of attack of the jet nozzle can be maintained better and more easily relative to the surface to be cleaned.

Exemplary embodiments of the invention are explained in more detail below with reference to the drawing.

Show it:

Figure 1 is a schematic representation of the overall structure of the blasting device;

FIG. 2 shows a section through an adapter of the blasting device;

Figure 3 shows a section through an adapter according to a modified embodiment;

Figures 4 and 5 sections through adapters according to further embodiments;

FIG. 6 shows a schematic illustration of the overall structure of a ner blasting device according to another embodiment;

FIGS. 7 and 8 show a side view and a front view of a nozzle unit of the blasting device;

Figures 9 and 10 sections through adapters according to further embodiments; and

11 shows a section through a unit consisting of an adapter and

Jet nozzle.

The blasting device shown in FIG. 1 comprises a pressure source 10, a blasting system 12 and a nozzle unit 14, consisting of an adapter 16 and a blasting nozzle 18 firmly connected to it.

The pressure source 10 is, for example, a compressor which supplies the blasting system 12 with compressed air via a line 20. The blasting system 12 is designed in a known manner to add a blasting agent, for example dry ice, to the compressed air serving as the blasting medium, so that a primary stream of the blasting medium and the blasting medium is fed to the adapter 16 via a line 22 formed, for example, by a hose. Furthermore, the pressure source 10 supplies a secondary stream of the blasting medium (compressed air) via a line 24, which is also designed as a hose, directly to a second inlet of the adapter 16. The primary stream and the secondary stream are combined in the adapter 16. The combined stream of sl medium and blasting medium is output at an increased flow rate via an outlet of the adapter 16 to the directly connected blasting nozzle 18, which expands the jet in a fan-shaped manner, so that a surface to be cleaned (not shown) has a relatively large working width the blasting medium can be irradiated and thereby cleaned. The blasting nozzle 18 is designed, for example, as a Venturi nozzle or Laval nozzle and has a constriction that accelerates the jet of the blasting medium to almost the speed of sound or also to supersonic speed.

A possible design of the adapter 16 is shown in section in FIG. 2. The adapter has a tubular housing 26, the inner cross section tapers in a conical section 28 towards the outlet 30. In this housing 26, an inner tube 32 is arranged coaxially, which forms with the housing 26 an annular space 34 closed at the rear end. An end of the inner tube 32 protruding from the housing 26 forms a first inlet 36 of the adapter, which is connected to the blasting system 12 via the line 22. A second inlet 38, which is oriented at right angles to the axis of the housing and is connected to the pressure source 10 via the line 24, is formed in the peripheral wall of the housing 26. The downstream end of the inner tube 32 lies in the region of the conical section 28 of the housing and is narrowed to form a nozzle 40.

The primary stream of blasting medium and blasting medium emerges from the inner tube 32 via the nozzle 40 and is combined with the secondary stream of the blasting medium which is supplied without swirling via the second inlet 38. The combined stream enters the jet nozzle 18 via the outlet 30 at increased speed.

Figure 3 shows an adapter 16 'according to a modified embodiment. The second inlet 38 is here shifted to the rear end of the housing 26, and the inner tube 32 is inserted into a block 42 which largely closes the annular space 34 downstream of the second inlet 38. In the block 42, a ring of channels 44 converging in the direction of flow is formed, which connect the annular space 34 to the interior of the inner tube 32. The secondary flow is here already supplied upstream of the nozzle 40 into the interior of the jet pipe 32 via the channels 44 (individual nozzles).

FIG. 4 shows a nozzle unit 14 ′ with an adapter 16 ″, which has an essentially tubular housing. The first inlet 36 and the second inlet 38 are formed here by Y-shaped tubes which open into the rear end of the adapter housing The first inlet 26 is coaxial with the adapter housing, while the second inlet 38 enters at an angle. The inner cross section of the tubular adapter housing is larger than the inner cross section of each of the first and second inlets 36, 38.

FIG. 5 shows an adapter 16 ′ ″ with a cup-shaped housing 26. The first inlet 36 is here arranged centrally and coaxially to the outlet 30, while the second inlet 38 is offset laterally and obliquely into the rear wall of the housing 26 entry.

FIG. 6 shows a blasting device according to a further exemplary embodiment, in which, in addition to the first blasting system 12, a second blasting system 46 is provided, with which it is possible to add a further blasting medium to the secondary stream supplied to the nozzle unit 14 via the line 24. For example, dry ice can be supplied via the first blasting system 12 and a stralil agent with a higher abrasion rate, for example granules, can be supplied via the second blasting system 46. Both blasting systems 12, 46 are fed via lines 20, 48 from the pressure source ^' ' 10. The nozzle unit 14 can have any of the configurations described in the other exemplary embodiments.

Since the primary stream and the secondary stream are combined in the adapter 16 and accelerated to a higher speed and the combined stream is accelerated further in the jet nozzle 18, the nozzle unit 14 has a high recoil when working with the jet device. To improve handling, it is therefore expedient to mount the jet unit 14 on a sack-cart-like chassis, as shown in FIGS. 7 and 8. The nozzle unit 14 is fastened here with clamping rails 50 to an elongated frame 52 which is provided at the lower end with two rollers 54 which roll on the surface to be cleaned during operation. The fan-shaped widened jet nozzle 18 is arranged such that the cleaning jet 18 is emitted over the rollers 54 onto the surface to be cleaned. The

, First inlet 36 of the adapter 16 is extended to a tube which protrudes beyond the end of the frame 52. The lines 22, 24 formed by hoses are not shown here. The line 22 is connected to the rear end of the tubular first inlet 36. A handle 56 for handling the device may be formed at the rear end of the frame 52 or at the rear end of the first inlet 36.

FIG. 9 shows a special embodiment of the adapter 16 shown in FIG. 2. The inner tube 32 is held longitudinally adjustable in the rear wall of the housing 26 by means of an external thread 58. It is thus possible to vary the clear width of the passage between the nozzle 40 and the conical section 28 of the housing 26 and thus to create a variable constriction for setting the flow rate of the secondary flow. It has proven to be advantageous if, in this embodiment, the second inlet 38 opens at right angles and centrally into the annular space 34.

To meter the secondary flow, it is expedient to arrange a throttle valve 60, for example a ball valve, at the first inlet 38, as shown in FIG.

FIG. 11 shows the nozzle unit 14 with the adapter 16 designed as in FIG. 10 and a fan-shaped blasting nozzle 18 which has a constriction 62 for accelerating the combined stream of blasting medium and blasting medium. The line 24 is formed here by a hose with a cross section of 1 1/4 ", while the second inlet 38 has only a cross section of 3/4". For the secondary current, a first constriction is formed at the transition between the line 24 and the first inlet 38, the cross section of which can be further reduced using the throttle valve 60. A second constriction for further acceleration of the secondary current is formed by the relatively small cross section of the annular space 34 here. Finally, the secondary flow is accelerated again at the variable constriction that is formed between the nozzle 40 and the conical section 28 of the adapter housing. When combined with the primary flow, the secondary flow thus has a high pressure and a high flow velocity, possibly even a supersonic velocity. Through the constriction 62, which has a diameter of 14 mm, for example, the combined current is accelerated to almost the speed of sound or supersonic. Due to this high flow velocity, an effective expansion of the jet emitted by the jet nozzle 18 is achieved. At the mouth, the jet nozzle 18 has a width of 160 mm, for example. The jet nozzle 18 shown in FIG. 11 can optionally also be combined with each of the adapters 16 ', 16 "and 16"'.

Experiments have shown that the arrangement shown in FIG. 11 can produce an effective expansion of the jet and an extremely high cleaning effect. It has been shown that such strong turbulence occurs in the flow that in the first test models there were even breakouts on the wall of the jet nozzle 18, which wall consisted of a 2 mm thick noble jet. This strong turbulence in connection with the high flow rate leads to an intensive cleaning effect. Surprisingly, it has been shown that even when using dry ice as the blasting agent no breakage or other damage to the dry ice particles occurs, so that they retain their cleaning effectiveness. By adjusting the length of the inner tube 34 and by adjusting the throttle valve 60, the jet geometry and the flow rate can be optimized. The secondary flow of the blasting medium is preferably supplied via line 24 with a higher pressure and higher volume output than the primary flow which is supplied via first inlet 36. For example, the volume outputs are in a ratio of 3: 2. An even more intensive cleaning effect could be achieved if a small amount of water was sprayed into the secondary stream.

Claims

πPATENTANSPRÜCHE

1. Blasting process for cleaning surfaces, in which in a stream of a blasting medium which carries an abrasive blasting medium, with the aid of an adapter (16), an additional blasting medium is supplied from a pressure source (10), characterized in that the supply of the additional blasting medium upstream of a blasting nozzle (18), which has a constriction (62), and that the pressure and volu en achievements for the blasting media are coordinated so that the blasting medium at the constriction (62) of the blasting nozzle (18) at least approximately Speed of sound reached.

2. The method according to claim 1, characterized in that the blasting agent is dry ice or dry snow.

3. The method according to claim 1 or 2, characterized in that a further blasting medium is added to the additional blasting medium.

4. The method according to claim 3, characterized in that the additional blasting agent is liquid.

5. Device for performing the method according to one of the preceding claims, with an adapter (16) with a first inlet (36) which is connected to a blasting system (12) and from the blasting system a primary stream of a blasting medium mixed with a blasting medium can be supplied and at least a second inlet (38), to which an additional blasting medium can be fed from a pressure source (10), and with an outlet (30), through which the primary stream and the additional blasting medium emerge, characterized by a directly at the outlet (30) of the adapter (16) connecting jet nozzle (18) having a constriction (62).

6. Blasting device according to claim 5, characterized in that the adapter (16) has an inner tube (32) connected to the first inlet (36), which forms an annular space (34) with a housing (26) of the adapter, in which the second inlet (38) opens.

7. blasting device according to claim 6, characterized in that the two- te inlet (38) opens at right angles and centrally into the annular space (34).

8. Blasting device according to claim 6 or 7, characterized in that the annular space (34) with the outlet (30) of the adapter (16) is connected via an annular passage which between the mouth of the inner tube (32) and a tapered Section (28) of the housing (26) is formed.

9. Blasting device according to claim 8, characterized in that the inner tube (32) is held longitudinally adjustable in the housing (26).

10. Blasting device according to one of claims 5 to 9, characterized in that a throttle valve (60) is arranged at the second inlet (38) of the adapter (16).

11. Blasting device according to one of claims 5 to 10, characterized in that the inner cross section of the second inlet (38) is smaller than the inner cross section of a line (24) which connects the second inlet to the pressure source (10).

12. Blasting device according to claim 8 and one of claims 9 to 11, characterized in that the cross section of the annular space (34) is smaller than the inner cross section of the second inlet (38).

13. Blasting device according to one of claims 5 to 12, characterized in that the unit (14) from adapter (16) and blasting nozzle (18) is mounted on a rollable frame (52).