FILTER FOR A HIGH-PRESSURE NOZZLE, HIGH-PRESSURE NOZZLE AND METHOD FOR PRODUCING A FILTER FOR A HIGH-PRESSURE NOZZLE

A filter for a high-pressure nozzle having a tubular section and a cap section. The cap section and/or the tubular section are provided with a plurality of filter slots which extend in the longitudinal direction of the tubular section and each have a first end situated on the side of the tubular section and a second end situated on the side of the cap section. A sleeve is arranged coaxially with the tubular section and covers the filter slots in the region of the first end of the filter slots.

CROSS-REFERENCE TO RELATED APPLICATIONS

This claims priority from German Patent Application No. 10 2015 214 123.3, filed on Jul. 27, 2015, the disclosure of which is hereby incorporated by reference in its entirety into this application.

FIELD OF THE INVENTION

The invention relates to a filter for a high-pressure nozzle having a tubular section and a cap section, wherein the cap section and/or the tubular section are provided with a plurality of filter slots, which extend in the longitudinal direction of the tubular section and each have a first end situated on the side of the tubular section and a second end situated on the side of the cap section.

BACKGROUND OF THE INVENTION

A high-pressure nozzle having a finer is known from European Patent EP 1 992 415 B1. High-pressure nozzles of this kind are provided for spraying liquids at pressures that may be several 100 bar to 600 bar. For example, high-pressure nozzles of this kind are used to descale steel products. For this purpose, a nozzle housing, which is provided with the filter, is inserted into a connection nipple or a connection tube. The liquid to be sprayed then passes through the filter slots into the flow channel of the high-pressure nozzle, which then leads to the nozzle outlet. It is proposed to embody the filter as a sintered part in order thereby to enable configuration of the end boundary surfaces of the inlet slots in any desired manner and, especially, in a manner which is favourable in terms of flow.

German Utility Model DE 297 06 863 U1 has disclosed another high-pressure nozzle. This high-pressure nozzle likewise has a filter, which is provided with a plurality of slots extending in the longitudinal direction. These slots are sawed into the filter housing by means of a circular saw blade.

A high-pressure nozzle for descaling steel products, having a filter which has a plurality of filter slots extending in the longitudinal direction of the tubular section of the filter, is also known from U.S. Pat. No. 4,848,672. The filter slots are sawed into the filter by means of a circular saw blade. Provided downstream of the filter is a jet straightener, which is inserted into the flow channel of the nozzle in order to align the flow in the longitudinal direction and, above all, to avoid turbulence.

SUMMARY OF THE INVENTION

The invention is intended to improve a filter, a high-pressure nozzle and a method for producing a filter.

According to the invention, this purpose is served by providing a filter for a high-pressure nozzle having a tubular section and a cap section, wherein the cap section and/or the tubular section are provided with a plurality of filter slots, which extend in the longitudinal direction of the tubular section and each have a first end situated on the side of the tubular section and a second end situated on the side of the cap section, in which a sleeve arranged coaxially with the tubular section is provided, said sleeve covering the filter slots in the region of the first end of the filter slots.

By means of the sleeve, the filter slots are covered in the region of the first end, which is situated on the side of the tubular section. As a result, the configuration of the first end of the filter slots no longer plays a role in the inflow of the liquid under high pressure, e.g. between 50 bar and 800 bar, into the filter or plays only a negligible role. This is because the sleeve covers the filter slots in the region of the first end of the filter slots, when seen in the radial direction. In order to flow in through the filter slots, the liquid must thus pass through the end of the sleeve and flows past the first end of the filter slots only to a negligible extent. Simply through providing a sleeve which conceals or covers the first end of the filter slots when viewed in the radial direction, a significant improvement in the flow conditions at a filter for high-pressure nozzles can be achieved. It has been observed that the formation of turbulence as the liquid flows in in the region of the first end of the filter slots can be prevented or largely avoided. Compared with high-pressure nozzles according to the prior art, in which the filter is produced as a sintered part, thus allowing the first end of the filter slots to be configured in a manner that is advantageous in terms of flow, or compared with mechanical finish machining of the first end of the filter slots, the solution according to the invention represents a considerable simplification, especially in terms of production engineering. After the sawing of the filter slots, the sleeve is arranged at least in the region of the first end of the filter slots. As a result, the filter slots no longer have to be finish-machined. This represents a considerable alleviation, especially when producing filters of this kind in large numbers, since the filter slots are normally very narrow and generally have a width of about 1 mm in order to perform their filtering function. The high-pressure nozzle according to the invention is provided for descaling steel products, for example.

As a development of the invention, the sleeve is arranged within the tubular section and/or the cap section and forms a flow channel through the filter, at least in some section or sections.

The arrangement of the sleeve within the tubular section and/or the cap section can be implemented in a relatively simple manner. For example, an axial bore is made in the filter housing, and the sleeve is then inserted into said bore. By means of the sleeve, the webs between the filter slots can be mechanically stabilized, this being advantageous especially when pressure surges occur.

As a development of the invention, a central bore of the sleeve is widened towards the upstream end.

The sleeve forms a flow channel through the nozzle, at least in some section or sections, and the liquid to be sprayed flows through the filter slots into the upstream end of the sleeve. Widening the central bore of the sleeve towards the upstream end can reduce a flow resistance of the sleeve and prevent the occurrence of turbulence, thereby ensuring enhanced performance from the high-pressure nozzle provided with the filter.

As a development of the invention, an end face of the sleeve is of rounded design at the upstream end.

Rounding the end face of the sleeve at the upstream end also contributes to a reduced flow resistance and, as a result, to an improvement in the performance of the high-pressure nozzle provided with the filter.

As a development of the invention, the sleeve rests against an outer side of the tubular section and/or of the cap section.

Arranging the sleeve on the outer side of the filter also makes it possible to cover or conceal the filter slots in the region of the first end of the filter slots. It is a particularly simple matter to arrange a sleeve on the outer side of the filter, e.g. simply by sliding the sleeve onto the filter and subsequently fixing it.

As a development of the invention, the sleeve rests against an outer side or an inner side of the tubular section or of the cap section, at least in the region of the first end of the filter slots.

Flow through the filter slots in the region of the first end of the slots is thereby largely prevented. As a result, the configuration of the first end of the filter slots plays only a negligible role or no role in relation to the flow resistance or any turbulence that occurs in the liquid entering the filter.

The problem underlying the invention is also solved by a high-pressure nozzle having a filter according to the invention.

As a development of the invention, provision is made in a high-pressure nozzle according to the invention for the sleeve to be arranged within the tubular section and to form a flow channel through the filter, at least in some section or sections, wherein a free flow cross section of the sleeve corresponds to the free flow cross section in the nozzle housing at the downstream end of the sleeve.

A stepless transition between the sleeve and the extension of the flow channel in the nozzle housing is thereby possible. It is thereby possible to prevent the occurrence of turbulence, and the performance of the high-pressure nozzle is improved.

The problem underlying the invention is also solved by a method for producing a filter for a high-pressure nozzle in which the sawing of filter slots into a tubular section and/or a cap section of the filter parallel to a longitudinal direction of the tubular section and the arrangement of a sleeve coaxially with the tubular section is provided, with the result that the sleeve covers the filter slots in the region of the first end of the filter slots.

Sawing filter slots into a tubular section and/or a cap section of the filter can also be achieved relatively simply and with a reliable process when producing in large numbers. Sawing filter slots is preferred here to milling filter slots. This is because the width of the filter slots is normally in a region of 1 mm, and the handling of milling cutters of such a diameter is extremely sensitive. The convexly shaped end of the filter slots which forms during the sawing of the filter slots no longer plays a role in terms of flow engineering if, in accordance with the invention, a sleeve is arranged coaxially with the tubular section, with the result that the sleeve covers the filter slots in the region of the first end of the filter slots. It is thereby possible in a surprisingly simple way to combine the production-engineering advantages of sawing the filter slots with a configuration of the first end of the filter slots which is advantageous in terms of flow.

As a development of the invention, the sleeve is arranged within the tubular section and/or the cap section.

As a development of the invention, the sleeve can be arranged on an outer side of the tubular section and/or of the cap section.

The scope of the invention covers the arrangement of two sleeves, namely a first sleeve being arranged within the tubular section and/or the cap section and a second sleeve being arranged on an outer side of the tubular section and/or of the cap section. Such a solution is complex but can be provided when special installation conditions, size ratios or flow conditions require it.

Further features and advantages of the invention will become apparent from the claims and the following description of preferred embodiments of the invention in combination with the drawings. Here, individual features of the different embodiments shown or described can be combined in any desired manner without exceeding the scope of the invention. In the drawings:

DETAILED DESCRIPTION

The illustration inFIG. 1shows a high-pressure nozzle10according to the invention, wherein the high-pressure nozzle10has a housing12, a nozzle14, only a section of which can be seen inFIG. 1, and a filter16connected to the housing12.

Liquid to be sprayed enters the filter16through a plurality of filter slots18extending in the longitudinal direction of the filter and passes through them into a flow channel (not visible inFIG. 1) in the interior of the nozzle housing12. The liquid to be sprayed passes to the nozzle mouthpiece14and specifically to the outlet opening in the nozzle mouthpiece14and emerges in the form of a fan jet in the embodiment shown.

The high-pressure nozzle10shown is provided for descaling steel products. A pressure of the liquid to be sprayed is typically in a range of from about 50 bar to several 100 bar, e.g. 800 bar. The mechanical requirements on the high-pressure nozzle10are therefore considerable since pressure surges can occur in the pipes leading to the high-pressure nozzle10, and these can then also have significantly higher pressure spikes. The filter16normally projects into a pipe through which the liquid to be sprayed is supplied. As a result, the filter16is exposed to high mechanical stresses, and turbulence which occurs as the liquid to be sprayed enters through the filter slots18also affects the performance of the high-pressure nozzle10in a disadvantageous way.

The illustration inFIG. 2shows the high-pressure nozzle10ofFIG. 1from behind, i.e. as seen in the direction of flow. It can be seen that the filter slots18are arranged in a radial direction in the filter16.

In the embodiment shown, the filter16has a tubular section20and a cap section22. The filter slots18extend in the longitudinal direction of the tubular section20and are arranged both in the cap section22and in the tubular section20.

From the ends of the filter slots18inFIG. 1andFIG. 2, it can be seen that these are made using a circular saw blade which ends in a linear edge at its circumference. For this reason, each of the ends of the filter slots18also runs out in an edge. In the context of the invention, provision is likewise made here to make the filter slots18with a saw blade which is of rectangular configuration at its circumferential edge.

The illustration inFIG. 3shows a side view of the high-pressure nozzle10. In this view too, the filter slots18introduced in the longitudinal direction of the tubular section20can be seen, extending from the cap section22into the tubular section20. In the illustrated embodiment of the high-pressure nozzle10, a circular-cylindrical section of the filter16is referred to as the tubular section20. The approximately hemi-spherical section which closes off one end of the tubular section20is then referred to as the cap section. In the embodiment illustrated, the filter16is of integral design. The filter16can be produced from a turned brass cap, into which the filter slots18are sawed, for example.

The illustration inFIG. 4shows the high-pressure nozzle10ofFIG. 1from the front. In addition to the nozzle housing12, the nozzle mouthpiece14with the outlet opening24can be seen.

The sectional view inFIG. 5enables the configuration of the filter slots18to be seen. The filter slots18each have a first end26and a second end28, wherein the first end26is situated on the side of the tubular section20and the second end28is situated on the side of the cap section22. The first end26is thus arranged at the downstream end of the filter slots18in the direction of flow through the high-pressure nozzle10and the second end28is arranged at the upstream end of the filter slots18, as seen in the direction of flow. As already explained, both ends26,28taper to an edge. This is brought about by the fact that the filter slots18are sawed using a circular saw blade that tapers at the edge. As already explained, the ends26,28of the filter slots18can also be of rectangular configuration if they are sawed using a saw blade of rectangular edge design.

In the illustration inFIG. 5, the filter slots18are sawed from the right. The circular saw blade is moved from right to left and thus cuts through the cap section22first and then enters the tubular section20. The feed motion of the saw blade is then stopped and the shape of the first end26of the filter slots18, which is arranged on the left inFIG. 5, is obtained. The shape of the first end26follows the outer contour of the saw blade and consequently forms a convex surface. Towards the centre of the filter16, this surface merges into a sharp edge, although this cannot be seen in the illustration inFIG. 5since a sleeve30is already arranged there. However, it can be seen in the illustration inFIG. 11how the edge at the transition between a central bore32of the filter16to the filter slots18is designed. More specifically, this circumferential edge follows a zigzag line caused by the configuration of the saw blade. The configuration of this edge inFIG. 11arises because a saw blade with a circumferential tapering edge is used. If, instead, a saw blade with an edge which does not taper but is rectangular is used, it would not be a zigzag line but an edge which was obtained, said edge being characterized by a plurality of grooves which are arranged spaced apart and are each rectangular.

In all cases, the profile of this sharp edge is of unfavourable configuration for flow and contributes to the generation of turbulence. To prevent the formation of such turbulence or at least to prevent it as far as possible, the sleeve30in the nozzle according to the embodiment inFIG. 5is inserted into the filter. For this purpose, the central bore of the filter is of step-shaped design, thus allowing the sleeve30to be inserted into the filter from the left as far as an offset34in the illustration inFIG. 5. The offset34is situated upstream of the first ends26of the filter slots18, as seen in the direction of flow. As a result, liquid which enters the filter16from outside through the filter slots18must flow into that end of the sleeve30which is situated upstream and on the right inFIG. 5. It can be seen fromFIG. 5that, as a result, the shape of the first end26of the filter slots18plays virtually no role anymore in relation to the liquid flowing in. This is because the decisive inlet edge for the liquid is now defined by that end of the sleeve30which is situated upstream and on the right inFIG. 5. As a consequence, there is now only a weak flow through the first end26of the filter slots since, of course, the sleeve30covers the filter slots18in the region of the first end26.

A central bore of the sleeve30is embodied so as to widen at its upstream end, i.e. the end situated on the right inFIG. 5. More specifically, a cone36which widens counter to the direction of flow is provided in the embodiment illustrated. The liquid to be sprayed enters via this cone36, which then tapers in the direction of flow. The flow resistance at the inlet to the sleeve30is thereby reduced. The end face of the sleeve30directed counter to the flow, i.e. the end face of the sleeve30arranged on the right inFIG. 5, can furthermore be of rounded design in order to further reduce a flow resistance. It should be taken into account here that it is only in the region of the filter slots18that this end face of the sleeve30arranged on the right inFIG. 5is impinged upon by the liquid to be sprayed. Between the filter slots18, the webs which separate the filter slots18also cover the end face of the sleeve30.

The illustrations inFIGS. 6 to 10show the filter16before assembly with the nozzle housing10. The filter16is secured in the housing10by means of a cylindrical section38, which can be provided with a thread.

The filter16is provided with two opposite, flat engagement surfaces40for a spanner to enable the filter16to be screwed into the housing10.

As already mentioned, the illustration inFIG. 11shows another embodiment of a filter16according to the invention. To avoid repetitions, only those features are described here which differ from those in the filter shown inFIGS. 1 to 10.

The filter16inFIG. 11is provided with a sleeve42, which rests against a radially outer outer surface of the filter16. As a result, the sleeve42covers the first ends26of the filter slots18and thereby prevents the shape of the first ends26of the filter slots18from being able to cause increased turbulence and, as a result, increased flow resistance, as the liquid to be sprayed enters the filter16.

More specifically, it can be seen fromFIG. 11that the liquid flows directly into the filter slots18from that end of the sleeve42which is situated on the right inFIG. 11, i.e. the upstream end. In the region of the first ends26of the filter slots18, in contrast, there is only a negligible flow. As a result, the shape of the first ends26of the filter slots18, which is determined by the sawing of the slots by means of a circular saw blade, causes only slight turbulence and only slightly increased flow resistance.

Since the sleeve42is mounted on the outside of the filter16inFIG. 11and rests on the outer surface of the filter16, the central bore32of the filter16itself forms a section of the flow channel through the high-pressure nozzle.

Both in the embodiment inFIGS. 1 to 10and the embodiment inFIG. 11, it has been found that, by virtue of the sleeves30and42, each covering the first ends26of the filter slots18, the ends situated on the side of the tubular section20of the filter16, the liquid to be sprayed is subject to so little turbulence after entering the filter16that it is normally possible to dispense with a jet straightener in the rest of the flow channel up to the outlet opening24. As a result, the high-pressure nozzle10according to the invention can be manufactured at low cost and, since a jet straightener always also causes flow resistance, is extremely powerful. More specifically, an “impact”, i.e. a contact impulse of the fan jet produced on a surface to be descaled, is greater in comparison with conventional nozzles according to the prior art.

If the inlet flow to the filter is very unfavourable, a jet straightener can have a calming effect on the flow. A jet straightener can be provided in the high-pressure nozzle according to the invention and can be installed in the sleeve30, for example.

The illustration inFIG. 12shows a connection nipple50, in which the high-pressure nozzle10according to the invention is installed, in a side view. In the view inFIG. 12, however, the high-pressure nozzle10is not visible. The connection nipple50has a tubular section52, onto the free end of which, at the top inFIG. 12, a union nut54is screwed.

In the sectional view inFIG. 13in section plane A-A inFIG. 12, it can be seen that the housing12of the high-pressure nozzle is preloaded against the connection nipple52by means of the union nut54. The high-pressure nozzle10is thereby held reliably and yet in an easily exchangeable manner on the connection nipple52. The connection nipple52can mark the end of a pipe via which the liquid to be sprayed is supplied. However, the connection nipple52can also be welded into a pipe extending perpendicularly to the connection nipple52, for example.

The illustration inFIG. 14shows the enlarged detail Y inFIG. 13. It shows the outlet opening24, from which a fan jet emerges and which is provided on a nozzle mouthpiece14. When viewed counter to the direction of flow, that is to say from top to bottom inFIG. 14, the mouthpiece14is followed within the nozzle housing10first of all by a ring seal56, then by an intermediate sleeve58and then, if appropriate with the interposition of a further ring seal (not shown), the sleeve30, which is inserted into the filter16. It can be seen that the diameter of a flow channel in the sleeve30corresponds to the diameter of the flow channel at the upstream end of the intermediate sleeve58. As a result, the liquid to be sprayed can be passed to the outlet opening24with small pressure losses.

The nozzle mouthpiece14advantageously consists of hard metal in order to ensure a long service life of the high-pressure nozzle10.