EP1992415B1 - High pressure nozzle and method for producing a high pressure nozzle - Google Patents

Abstract

The nozzle (10) has a feed channel with a beam directing device (26) formed with a discharge opening (22). A neck of the feed channel is provided downstream to the beam directing device. The beam directing device comprises a free flow section in a proximate region that encloses a center longitudinal axis (30) of the feed channel. The nozzle fastens a section with constant width at the neck of feed channel, where the section is crossed over a tapered discharge chamber. The section includes length that is twice the length of the neck of the feed channel. An independent claim is also included for a method for manufacturing a high pressure nozzle.

Description

The invention relates to a high-pressure nozzle with a jet straightener within a feed channel to an outlet opening.

From the European patent EP 0 792 692 B1 a high-pressure nozzle for descaling steel products is known, which has a jet funnel within a feed channel to an outlet opening. The jet straightener is constructed as a star-like component in cross-section and has a cylindrical central part, from which radially flow guide surfaces extend. In order to reduce the flow resistance of the jet director, the cylindrical central part is extended both in the upstream direction and in the downstream direction in the form of a conical tip. Upstream of the jet straightener, a filter is arranged, which is formed from a pipe section with a spherical cap-shaped end and with radial cuts for entry is provided by liquid. The radial cuts extend into the spherical section cap of the filter. Downstream of the jet director, a gradual taper of the flow channel is provided which extends with decreasing taper angle to an exit chamber in a mouthpiece. The mouthpiece has the outlet chamber and the outlet opening adjoining the outlet chamber. Due to the very high liquid pressures with which high-pressure nozzles are operated for descaling steel products and which can be several 100 bar to 600 bar, a low flow resistance is crucial because pressure losses within the high-pressure nozzle either to a lower removal or to the requirement of a higher pressure Feed the supply line. In addition, the shape of the flat jet generated is crucial, which should have the smallest possible width to achieve the best possible removal effect. Finally, the high-pressure nozzle is exposed to considerable mechanical loads, since, for example, pressure surges in the supply line can lead to collapse of the filter of the high-pressure nozzle.

From the U.S. Patent US 5,169,065 a high-pressure nozzle for removing material is known, in which a jet straightener is provided, which is formed of a solid and provided in the longitudinal direction with numerous cylindrical through holes cylinder. One of these through holes surrounds the central longitudinal axis of the nozzle. When viewed in the direction of flow, the jet director is followed by a short, constant section and then by a strong taper. Subsequent to a point of least cross-section, the feed channel expands again slightly, in order then to extend to an outlet opening with a constant cross-section.

The Japanese Patent Abstract JP 08 296 151 describes a Webdüse in which a water jet, which surrounds a thread, with a Beam director is aligned, which has radially extending in the direction of its central longitudinal axis extending flow guide.

The Japanese Patent Abstract JP 2006 122 834 describes a jet straightener, which comprises a cylindrical disk with a total of seven parallel to the flow direction cylindrical bores. The middle of these holes concentrically surrounds the central longitudinal axis of the jet director.

The German design text DE 1 185 566 describes a tank cleaning device in which a jet straightener is provided upstream of an outlet opening. The jet director is formed by means of a plurality of cylindrical bores, which are introduced into the wall of a cylinder tube. The holes are thereby placed so that their circumference extends beyond the inner wall of the cylindrical tube, so that in the direction of the central longitudinal axis of the tube extending flow guide surfaces are formed.

The international Publication WO 98/00214 describes a toy water gun with different versions of jet straighteners. A jet straightener has a plurality of planar flow guide surfaces extending in the direction of a central longitudinal axis of a feed channel.

The American publication US 2006/0255167 A1 shows a beam director, which is formed by means of a plurality of cylindrical bores in a disc. The middle of these holes surrounds a central longitudinal axis of the nozzle concentric.

The German utility model DE 91 09 175 U1 describes a high-pressure nozzle for descaling steel products. downstream a jet director, a supply channel is provided, which tapers in three stages up to an outlet opening.

The European Patent Application EP 1 293 258 A1 describes a spray nozzle in which downstream of a jet straightener also a three-stage taper of a feed channel is provided.

With the invention, an improved high-pressure nozzle is to be provided.

According to the invention for this purpose is a high-pressure nozzle, in particular for descaling steel products, according to claim 1.

In this way, a so-called soulless beam judge is realized, which is characterized on the one hand by a low flow resistance and on the other hand by a very good alignment effect. The beam director therefore has a central longitudinal axis immediately surrounding Flow channel without fittings on. Compared to conventional jet straighteners, which have a central cylindrical component, from which radially outward flow guide, the jet straightener according to the invention has a significantly reduced flow resistance, as the flow channel immediately surrounding the central longitudinal axis of the feed channel remains free and can be used for unimpeded flow. Since the free cross-section available for the flow is considerably larger, a significant reduction of the flow resistance is achieved. The free flow cross section may, for example, have a radius which is about 1/5 of the inner radius of the jet director.

In a development of the invention, the jet straightener has flow guide surfaces which extend parallel to the central longitudinal axis of the feed channel and onto the central longitudinal axis.

By means of such aligned parallel to the central longitudinal axis of the feed channel flow directors, a good directivity of the jet director can be achieved and a flow that has passed the jet director is downstream of the beam director substantially completely aligned parallel to the central longitudinal axis.

In a further development of the invention, the flow guide surfaces extend radially in the direction of the central longitudinal axis.

In this way, planar flow guide can be realized 'have a very good alignment effect with low flow resistance.

According to the invention, a rejuvenation of the feed channel is provided downstream of the jet director.

By means of such a taper, the flow can be concentrated and the flow channel can be brought together in a short path to the cross section of the outlet chamber. According to the invention, a short taper is provided and the tapered portion of the feed channel has only about half to one third of the length of the beam director.

According to the invention, a portion of constant cross section adjoins the taper downstream of the jet director, which merges into a tapering discharge chamber.

By means of such a section with a constant cross-section, a flow calming can be achieved, which results in a very good beam quality with low flow resistance. The section with constant cross-section is longer according to the invention than the taper after the beam director. It has been found to be advantageous to form the section of constant cross-section at least twice as long as the taper after the jet director and in particular seven times as long as the taper. The outlet chamber merges into the outlet opening, from which the spray jet then emerges.

In a further development of the invention, a filter is arranged upstream of the jet straightener, which has radially aligned to the central longitudinal axis entry slots. The entry slots advantageously extend parallel to the central longitudinal axis. The filter may have a spherical segment-shaped filter cap which has inlet openings which extend parallel to the central longitudinal axis.

The inlet openings in the spherical segment-shaped filter cap are separated from the inlet slots of the filter, so that the spherical segment-shaped filter cap can be made very stable and in particular possibly occurring in the supply lines pressure surges can withstand. For example, the filter cap has a circumferential collar, which ensures high mechanical strength. The inlet slots in the filter thus end in front of the spherical segment-shaped filter cap.

In a further development of the invention are Endbegrenzungsflächen the entry slots, which lie on the side of the beam director, rounded or obliquely formed inwardly leading, the rounded Endbegrenzungsflächen are designed to be convex in the direction of the central longitudinal axis. The respective slot bottom of the entry slots, which, viewed in the direction of flow, lies on the side of the beam director, is thus arched outwardly or convexly in the direction of the central longitudinal axis. Alternatively, the slot base is inclined inwards and, in particular, has a cone-shaped jacket-shaped section, with the cone then tapering in the direction of flow. As a result, the flow through the inlet slots in the region of the slot bottom is gradually deflected in the direction of the central longitudinal axis. As a result, a vortex formation in the region of the slot bottom is considerably reduced and a low flow resistance and a flow oriented substantially parallel to the central longitudinal axis downstream of the jet director are achieved.

In a further development of the invention, the filter is formed by means of a filter cap and a filter main part, wherein the filter cap and the main filter part are produced as individual parts and then inextricably linked together.

In this way, the production of geometrically complicated shapes in the range of filter cap and filter body is facilitated. After the non-detachable connection of the filter cap and main filter part, a stable and streamlined filter unit is available.

In a further development of the invention, the filter cap and the filter body are made by metal injection molding and then sintered together.

Metal powder injection molding can also be used to realize geometrically complicated shapes which could not be realized by mechanical machining or only with considerable effort. This includes, for example, aligned with the central longitudinal axis, convex formation of the end faces of the inlet slots of the filter. Typically, such entry slots are formed by dipping a mill or saw blade into a tubular member. This then usually results in an outwardly directed, concave configuration of the end faces, which is unfavorable in terms of flow.

In a further development of the invention, the filter main part on the jet judge.

In this way, a streamlined combined Strahlrichter- and filter component can be realized. When producing this combined Strahlrichter- and filter component by means of metal powder injection molding, the soulless jet straightener according to the invention and a streamlined design of the entry slots on the filter can be realized and produced in a series production. Alternatively, the jet straightener can also be designed as a separate flow channel component or be integrated into another component of the nozzle as the filter.

In a further development of the invention, the filter cap on a circumferential collar with radially inwardly extending projections, wherein the projections engage in matching recesses of the filter body.

In this way, a very stable connection of the filter cap to the filter body can be realized, which also allows a very aerodynamic training. Alternatively, the filter body may be provided with a circumferential collar having radially inwardly or outwardly extending projections, the projections then engaging mating recesses of the filter cap. Regardless of whether the circumferential collar is provided with radially extending projections on the filter cap or the main filter part, the advantages of the invention a very stable and aerodynamic design of the connection between the filter cap and filter main part can be realized.

In a further development of the invention, the filter main part at its, the filter cap adjacent end parallel to the central longitudinal axis extending webs, between which the recesses are formed. Advantageously, the entry slots are formed between the webs of the main filter part.

The filter main part accordingly has distributed over its circumference a plurality of extending in the upstream direction of the fingers or webs, between which the entry slots are formed. The ends of these webs are received and fixed by the filter cap. After the permanent connection of the filter main body and the filter cap, this creates a stable component. Particularly advantageous filter cap and filter body can be made by means of metal injection molding and then sintered together.

Fig. 1

eine perspektivische, aufgeschnittene Ansicht einer erfindungsgemäßen Hochdruckdüse,

Fig. 2

eine Schnittansicht der Hochdruckdüse der Fig. 1,

Fig. 3

eine Schnittansicht eines kombinierten Strahlrichter- und Filterbauteils der Hochdruckdüse der Fig. 1,

Fig. 4

eine perspektivische Ansicht eines Filterhauptteils mit integriertem Strahlrichter des Bauteils der Fig. 3,

Fig. 5

eine Seitenansicht des Filterhauptteils der Fig. 4,

Fig. 6

eine Ansicht des Filterhauptteifs der Fig. 5 in Richtung des Pfeiles VI,

Fig. 7

eine Ansicht des Filterhauptteils der Fig. 5 entlang dem Pfeil VII,

Fig. 8

eine Ansicht des Filterhauptteils der Fig. 5 auf die Schnittebene VIII-VIII,

Fig. 9

eine vergrößerte Darstellung einer Einzelheit des Filterhauptteils der Fig. 8,

Fig. 10

eine weitere Seitenansicht des Filterhauptteils der Fig. 4,

Fig. 11

eine Schnittansicht des Filterhauptteils der Fig. 10 auf die Schnittebene XI-XI,

Fig. 12

eine Seitenansicht einer Filterkappe des Bauteils der Fig. 3,

Fig. 13

eine Ansicht der Filterkappe der Fig. 12 in Richtung des Pfeiles XIII,

Fig. 14

eine Schnittansicht auf die Schnittebene XIV-XIV der Fig. 13,

Fig. 15

eine Schnittansicht auf die Schnittebene XV-XV der Fig. 13 und

Fig. 16

eine schematische Darstellung zur Verdeutlichung eines Verfahrens zum Herstellen einer Sprühdüse, das nicht teil der Erfindung ist.

Further features and advantages of the invention will become apparent from the claims and the following description of a preferred embodiment of the invention. In the drawings show:

Fig. 1

a perspective, cutaway view of a high-pressure nozzle according to the invention,

Fig. 2

a sectional view of the high pressure nozzle of Fig. 1 .

Fig. 3

a sectional view of a combined Strahlrichter- and filter component of the high pressure nozzle of Fig. 1 .

Fig. 4

a perspective view of a filter main part with integrated beam funnel of the component of Fig. 3 .

Fig. 5

a side view of the main filter part of Fig. 4 .

Fig. 6

a view of the filter Hauptteifs the Fig. 5 in the direction of the arrow VI,

Fig. 7

a view of the filter body of the Fig. 5 along the arrow VII,

Fig. 8

a view of the filter body of the Fig. 5 on the cutting plane VIII-VIII,

Fig. 9

an enlarged view of a detail of the main filter part of Fig. 8 .

Fig. 10

another side view of the main filter part of Fig. 4 .

Fig. 11

a sectional view of the filter main part of Fig. 10 on the cutting plane XI-XI,

Fig. 12

a side view of a filter cap of the component of Fig. 3 .

Fig. 13

a view of the filter cap the Fig. 12 in the direction of the arrow XIII,

Fig. 14

a sectional view on the cutting plane XIV-XIV of Fig. 13 .

Fig. 15

a sectional view on the section plane XV-XV of Fig. 13 and

Fig. 16

a schematic representation for illustrating a method for producing a spray nozzle, which is not part of the invention.

The perspective, cut view of the Fig. 1 shows a high-pressure nozzle 10 according to the invention for the descaling of steel products. The high-pressure nozzle 10 is installed in a tubular connection nipple 12 and secured in this tubular connection nipple 12 by means of a union nut 14. The high-pressure nozzle 10 itself has a combined filter and Strahlrichterbauteil 16 which is screwed into a nozzle housing 18. In the nozzle housing 18, in turn, a mouthpiece 20 is inserted, which defines an outlet opening 22 at its downstream end. The tubular connection nipple 12 is connected to a nozzle bar, not shown, in which a filter 24 of the high-pressure nozzle 10 projects. Liquid entering through the filter 24 into the high-pressure nozzle 10 flows via a jet funnel 26 and ultimately reaches the mouthpiece 20 and exits from the outlet opening 22 in the form of a flat jet. The mouthpiece 20 is sealed against the nozzle housing 18 by means of a circumferential metal solder seam 28.

Based on Fig. 1 It can easily be seen that the jet straightener 26 leaves open a flow channel directly surrounding a central longitudinal axis 30 of the high-pressure nozzle 10. In the area of the beam director 26, a flow channel immediately surrounding the central longitudinal axis 30 is thus present without any internals. The jet straightener 26 has a plurality of flow guide surfaces extending radially in the direction of the central longitudinal axis 30, which are planar and aligned parallel to the central longitudinal axis 30. By means of the jet director 26, the liquid entering the filter 24 can be aligned parallel to the central longitudinal axis 30. As will be explained later as well as in Fig. 1 can be seen, the plurality of flow guide of the jet director 26 are only attached to the outer periphery of the jet director and protrude freely in the direction of the central longitudinal axis 30 surrounding the flow channel.

In the sectional view of Fig. 2 can be seen two opposing flow control of the beam director 26 through which the cutting plane is laid. Upstream of the jet director 26, the filter 24 is arranged, which is formed from a circular cylindrical tube section with radially extending to the central longitudinal axis 30 entry slots and which is provided with a spherical segment-shaped filter cap.

Downstream of the beam director 26, a conically tapered section 32 connects, which merges into a circular cylindrical section 34 with a constant diameter. The tapered section 32 is shorter than the beam straightener 26 and has about 1/3 to 1/2 of the length of the beam director 26. In contrast, the constant section portion 34 downstream of the tapered portion 32 is both significantly longer than the beam director 26 and significantly longer than the tapered portion 32. In the illustrated embodiment, the constant cross section 34 is about three times as long as the beam director 26 and has about seven times Length of the tapering section 32. It has been found that such a dimensioning of the lengths of jet straightener 26, the taper 32 and the section 34 with constant cross-section can set flow conditions that favor an exact formation of an exiting flat jet 36. Downstream of the constant diameter section 34 is an exit chamber 38 in the mouthpiece 20. The outlet chamber 38 tapers conically and ends at the outlet opening. The length of the exit chamber 38 is about half the length of the jet director 26 and significantly less than the length of the section 34 of constant cross section. The length of the outlet chamber 38 is approximately on the order of the taper 32 immediately downstream of the Strahlrichters 26th

In the high-pressure nozzle according to the invention, a free flow channel available to the flow is thus tapered in a relatively short path in two stages, namely once through the tapered section 32 immediately downstream of the jet director 26 and then also in a comparatively short way by means of the tapering exit chamber 38. It has been found that such a two-stage, respectively relatively strong constriction of the flow channel in a short way flow is cheaper than a very gradual taper over a long way. Specifically, the available free cross-section is relatively strongly constricted by means of the section 32 in the short path, but in the course of the long section 34 with constant cross-section, the flow can calm down again, and then very evenly enter the outlet chamber 38.

The largest free flow cross section is in the region of the filter 24 and is determined by the sum of the free cross sections of the elongate filter slots and the other filter slots in the filter cap. An already significantly reduced flow cross section is in the range of Beam director 26 before, wherein the free flow cross-section results there from the cross section of the total channel minus the end faces of the radially arranged flow guide. A ratio of the free flow cross-sectional area on the jet straightener 26 to the free flow cross-sectional area of the filter 24 is advantageously 1: 6 or greater.

A further narrowing of the flow cross section takes place after the jet straightener 26 on the cross section of the channel 27, which is guided with a constant cross-section to the mouthpiece 20. A ratio of the free flow cross-sectional area in the channel 27 to the free flow cross-sectional area on the jet straightener 26 is advantageously 1: 1.23 or greater.

A ratio of the free flow cross-sectional area in the channel 27 to the free flow cross-sectional area of the filter 24 is advantageously 1: 7.44 or greater.

The free flow cross-sectional area in the channel 27 is for example 95 mm ² , the free flow cross-sectional area in the jet straightener 26, for example, 117 mm ² and the free flow cross-sectional area on the filter 24 is for example 707 mm ² .

At the upstream end of the mouthpiece 20, a Metalllotnaht 28 is provided between an inner wall of the nozzle housing 14 and an annular end face of the mouthpiece 20, which seals the mouthpiece 20 against the nozzle housing 14.

The sectional view of Fig. 3 shows the combined Strahlrichter- and filter component 16 of the high-pressure nozzle 10 of Fig. 1 , The component 16 consists of a total of three individual parts which are permanently connected to each other, namely a filter cap 40, a filter main part 42, the also has the jet funnel 26, and a conduit part 44 having the tapered portion 32 downstream of the jet director 26 and the constant cross-section portion 34. At its downstream end, the conduit part 44 is provided with an external thread 46 with which the conduit part 44 is screwed into the nozzle housing 18.

The filter cap 40 is designed in the form of a spherical segment and has inlet openings 48 extending parallel to the central longitudinal axis 30. The inlet openings 48 are arranged in a star shape on the filter cap 40. The filter main part 42 has a plurality of webs 50 extending parallel to the central longitudinal axis 30 and spaced uniformly around their circumference. Between the webs 50 remain entry slots through which liquid can enter the filter 24.

Based on Fig. 3 It can be clearly seen that downstream end faces 52 of the entry slots are rounded and curved in the direction of the central longitudinal axis 30 to be convex. Liquid entering through the entry slots is thereby gradually deflected in the direction of the central longitudinal axis 30 in the area of the downstream end faces of the entry slots. As a result, a vortex formation in the region of the end faces 52 is kept low and a low flow resistance with uniform flow can be achieved.

Good to see in Fig. 3 Furthermore, that the radially in the direction of the central longitudinal axis 30 to be extended, planar flow guide surfaces 54 of the Strahlrichters 26 a the central longitudinal axis immediately surrounding flow channel 56 without internals release.

The filter cap 40, the main filter part 42 with the jet straightener 26 and the conduit part 44 are manufactured as individual parts by means of metal injection molding and then put together after removal of a thermoplastic binder, as individual precursors and then sintered. After sintering, the filter cap 40, the main filter part 42 and the conduit part 44 are permanently connected to each other and form the heavy-duty combined Strahlrichter- and filter component 16. The preparation by means of metal powder injection molding will be explained in detail.

The presentation of the Fig. 4 shows in a perspective view the main filter part 42 of Fig. 3 , Dashed lines indicate details that are not recognizable in and of themselves, such as the radially oriented flow guide surfaces 54 and inherently concealed entry slots between the webs 50. The webs 50 are formed at their upstream end with reduced thickness, so that each web 50 has a heel 58, which serves as a stop when sliding the filter cap 40, as well as in the side view of Fig. 5 can be seen.

The view of Fig. 6 in the direction of the arrow VI Fig. 5 shows the radially extending in the direction of the central longitudinal axis flow guide surfaces 54 of the jet director, which leave the flow channel 56 around the central longitudinal axis 30 around. As already explained, the flow guide surfaces 54 are only connected at their radially outer end to the inner wall of the main filter part 42 and protrude freely in the direction of the central longitudinal axis. Based on the view of Fig. 6 It can be clearly seen that the flow guide surfaces 54 leave a comparatively equal cross-section and, despite a very good alignment effect, cause only a small flow resistance. All, protruding into the flow edges of the flow guide surfaces 54 are rounded.

The presentation of the Fig. 7 shows a view of the filter main part 42 in the direction of arrow VII of Fig. 5 , Good to see the free ends of the webs 50, each with a paragraph 58. The webs 50 leave between them entry slots free to extend radially in the direction of the central longitudinal axis and can enter through the liquid in the interior of the filter body 42. The number of slots between the webs 50 is greater than the number of flow baffles. Overall, in the embodiment shown, there are eight flow guide surfaces 54 and fourteen inlet slots which are distributed uniformly over the circumference of the main filter part 42.

The sectional view of the filter main part 42 in FIG Fig. 8 on the cutting plane VIII-VIII of the Fig. 5 allows the rounded formation of the end faces 52 of the entry slots between the webs 50 of the filter 24 to recognize.

The end faces 52 of the entry slots are curved and, in particular, the sectional view of Fig. 11 on the cutting plane XI-XI the Fig. 10 can be seen, viewed in the direction of the central longitudinal axis 30 convex. In addition, the transitions between the end faces 52 and the lateral boundaries of the webs 50, which define the entry slots, rounded, as well especially in the enlarged detail of the Fig. 9 can be seen. The liquid entering through the entry slots is thereby deflected in the direction of the central longitudinal axis 30 with little vortex formation and thus low flow losses. Also rounded are the free edges of the flow guide surfaces 54 of the Strahlrichters 26, such as Fig. 11 and also 6 and 7 can be seen.

The presentation of the Fig. 12 shows the filter cap 40 in a side view. The filter cap 40 is formed substantially spherical segment-shaped and has star-shaped around the central longitudinal axis 30 arranged inlet openings 48 which are parallel to the central longitudinal axis 30th extend. Liquid can enter through the inlet openings 48 into the interior of the filter and is already aligned with the inlet approximately parallel to the central longitudinal axis 30. The filter cap 40 has an indexing slot 60, which facilitates the correct angle placing the filter cap 40 on the main filter part 42.

The presentation of the Fig. 13 shows a view of the filter cap 40 along the arrow XIII of Fig. 12 , As can be seen, the filter cap 40 has a circumferential collar 62 with a plurality of projections 64 extending radially in the direction of the central longitudinal axis 30. Recesses 66, which are provided for receiving the free ends of the webs 50 of the main filter part 42, are respectively formed between the projections 64. The thickness of the webs 50 corresponds to the wall thickness of the filter cap 40 and thus the radial dimension of the projections 64 plus the thickness of the collar 62, so the length of the outer wall of the filter cap 40 to the inner wall in the region of a projection 64. As already with reference to Fig. 5 has been explained, the free ends of the webs 50 are reduced in thickness. When placing the filter cap 40, therefore, the free ends 59 engage in the recesses 66 and the free ends 59 are matched to the dimensions of the recesses 66, that an inner wall of the webs 50 in the pushed state of the cap 40 in alignment with the inner wall of the filter cap 40th runs. The filter cap 40 is pushed so far until the peripheral collar 62 rests with its lower edge on the shoulder 58 of the filter body 42. Since the material thickness of the webs 50 corresponds to the wall thickness of the filter cap 40, after placing the filter cap 40 on the main body 42, both the outer wall of the webs 50 and the outer wall of the filter cap 40 and the inner wall of the webs 50 and the inner wall of the filter cap 40 are aligned aligned with each other. This is also the sectional view of the Fig. 3 of the assembled combined Strahlrichter- and filter component 16 can be seen. Already in the assembled state of the filter cap 40 and the main filter part 42 are characterized only very narrow joints between the filter cap 40 and the filter body 42 is present.

Advantageously, both the filter cap 40 and the main filter part 42 are produced by metal powder injection molding and sintered after debindering in the assembled state. By sintering, the filter cap 40 and the main filter part 42 connect inextricably and also after the plugging still existing narrow joints are filled, so that after sintering a one-piece and substantially seamless component is obtained.

Fig. 14 represents a sectional view on the cutting plane XIV-XIV of Fig. 13 and Fig. 15 represents a sectional view on the section plane XV-XV of Fig. 13 represents. FIGS. 14 and 15 It can be seen that the wall thickness of the filter cap 40 gradually decreases from the collar 62 in the direction of its vertex, ie the intersection of the central longitudinal axis 30 with the wall of the filter cap 40. By such a design, the length of the entry slots 48 parallel to the central longitudinal axis 30 are kept as short as possible, which benefits a low flow resistance, and at the same time the filter cap 40 can be made extremely stable, so that it withstands strong pressure surges during operation of the high-pressure nozzle according to the invention.

Based on the schematic representation of Fig. 16 the method according to the invention for producing a high-pressure nozzle by means of metal powder injection molding will be explained.

In a first method step 70, metal powder is mixed with a thermoplastic plastic binder. As a metal powder, for example, hard metal powder can be used. The mixture thus obtained is also referred to as a feedstock.

In a second step 72, the mixture thus obtained is then shaped by means of injection molding. Can be used essentially conventional injection molding machines, since the mixture has indeed because of the thermoplastic plastic binder plastic-like properties and is suitable for injection molding. The precursor obtained after the injection molding is called a green component or green component.

A subsequent step 74 is referred to as debinding, and in the course of this step 74 the thermoplastic binder is removed from the precursor by suitable processes. These can be, for example, thermal or chemical processes. After debindering, there is a precursor having a comparatively porous structure in which there are interstices between the individual metal powder particles which were originally filled by the thermoplastic binder. The precursor obtained after debindering is also referred to as Braunling or brown component.

After debindering, individual parts may be assembled in a step 76. As has been described, the filter cap 40, the main body part 42 with the jet straightener 26 and the pipe part 44 are separately manufactured by metal powder injection molding and assembled after debindering. The conduit member 44 may also be manufactured as a conventional rotary member and then assembled with the debindered precursors, namely the filter cap 40 and the filter body 42.

In the assembled state of the precursors they are sintered in a step 78. The sintering is carried out by a heat treatment process. After sintering, the material properties of the resulting end product are comparable to those of solid materials. The assembled items, especially the filter cap 40, the filter body 42 and the lead portion 44, are inextricably linked by the step 78 of sintering and any existing joints between these items disappear. Outer wall and inner wall of the combined Strahlrichter- and filter component 16 thereby extend smoothly and without noticeable joints. This benefits a low flow resistance.

In a concluding step 80, the components sintered together, that is to say the combined jet straightener and filter component 16, can still be post-processed or surface-treated. For example, the accessible surfaces can be polished in order to reduce the flow resistance even further.

The combined Strahlrichter- and filter component 16 produced by metal powder injection molding can be designed aerodynamic and high-strength at the same time. The use of metal powder injection molding thereby allows surprising improvements to conventional high-pressure nozzles.

Claims (9)

1. High pressure nozzle, in particular for removing scale from steel products, having a jet straightener (26) inside a feed duct to an outlet opening (22), where said jet straightener (26) has a free flow cross-section in an area directly surrounding the central longitudinal axis (30) of the feed duct, where a tapered portion (32) of the feed duct is provided downstream of the jet straightener (26), where a section (34) with constant cross-section adjoins the tapered section (32) downstream of the jet straightener (26) and merges into a tapering outlet chamber (38), where the section (34) with constant cross-section is at least twice as long as the tapered section (32) downstream of the jet straightener (26), and where the feed duct between the jet straightener (26) and the outlet opening (22) is tapered in two stages by the tapered section (32) and by the tapering outlet chamber (38).
2. High pressure nozzle according to Claim 1, characterized in that the jet straightener (26) is designed in one piece with a flow duct component of the high pressure nozzle.
3. High pressure nozzle according to at least one of the preceding claims, characterized in that upstream of the jet straightener (26) a filter (24) is arranged that has inlet slits aligned radially to the central longitudinal axis (30).
4. High pressure nozzle according to Claim 3, characterized in that end faces (52) of the inlet slits located on the side of the jet straightener (26) are designed rounded or leading obliquely inwards, where the rounded end faces (52) are designed convex when viewed in the direction towards the central longitudinal axis (30).
5. High pressure nozzle according to Claim 3 or Claim 4, characterized in that the filter (24) is formed by means of a filter cap (40) and of a filter main part (42), where said filter cap (40) and said filter main part (42) are made as individual parts and then inseparably connected to one another.
6. High pressure nozzle according to Claim 5, characterized in that the filter cap (40) and the filter main part (42) are made by metal injection moulding and then sintered together.
7. High pressure nozzle according to at least one of Claims 5 and 6, characterized in that the filter cap (40) or the filter main part (42) has an all-round collar (62) with radially extending projections (64), where said projections engage in matching recesses of the filter main part (42) or of the filter cap (40).
8. High pressure nozzle according to at least one of Claims 5, 6 and 7, characterized in that the filter cap (40) has an all-round collar (62) with radially inward-extending projections (64) which engage in matching recesses of the filter main part (42).
9. High pressure nozzle according to Claim 8, characterized in that the filter main part (42) has, at its end adjacent to the filter cap (40), bars (50) extending parallel to the central longitudinal axis (30) and between which the recesses are formed.

Images