CN111421714A

CN111421714A - Method for producing a matrix for a spiral nozzle, spiral basic-shape male part and spiral nozzle

Info

Publication number: CN111421714A
Application number: CN201910307516.3A
Authority: CN
Inventors: J.施派尔; P.布劳恩
Original assignee: Lechler GmbH
Current assignee: Lechler GmbH
Priority date: 2019-01-10
Filing date: 2019-04-17
Publication date: 2020-07-17
Also published as: DE102019200212A1

Abstract

The invention relates to a method for producing a matrix for a spiral nozzle, a spiral basic-shape male part and a spiral nozzle. The method for manufacturing a female mold for a spiral nozzle comprises the steps of: embedding the helical basic shape convex piece into the molding compound; curing the molding compound; removing the helical basic shape male part from the cured moulding compound in order to produce a helical basic shape female part; incorporating a tapered gap into the helical basic shape female part, wherein the tapered gap is incorporated coaxially with a central longitudinal axis of the helical basic shape female part, and thereby producing a helical shape female part; and disposing a tapered core in the helically shaped female part.

Description

Method for producing a matrix for a spiral nozzle, spiral basic-shape male part and spiral nozzle

Technical Field

The invention relates to a method for producing a matrix for a spiral nozzle. The invention further relates to a helical basic-shape projection for producing a die for a helical nozzle, and to a helical nozzle.

Background

The helical nozzle has, at least in part, a coreless spiral. The liquid is directed into the interior space of the screw and then travels onto the helical surface of the screw facing away from the tip and is thereby distributed in the spray cone. The spiral nozzle is suitable for high liquid throughput and is insensitive to clogging. The known spiral nozzle is integral and manufactured by means of investment casting. Spiral nozzles are usually manufactured by means of a cast metal mold having a core. To manufacture the cast metal mold, the core is fitted into the at least partially coreless spiral of the fully functional spiral nozzle, and then the metal mold is manufactured by recasting. In the case of this method, it is disadvantageous that, in order to modify the output data (e.g. throughput) of the spiral nozzle, it is always necessary to manufacture a new separate mold, for which purpose a fully functional spiral nozzle, which has been previously conceived experimentally and specially processed, must be embedded. In the case of the manufacture of the known mould, there is furthermore the problem that the core and the spiral nozzle must be joined without any gap, which sets high requirements in terms of the manufacture of the core.

Disclosure of Invention

By means of the invention, an improved method for manufacturing a female mold for a spiral nozzle, an improved spiral basic shape male member for manufacturing a mold for a spiral nozzle, and an improved spiral nozzle will be provided.

According to the invention, for this purpose, a method for manufacturing a matrix for a spiral nozzle is provided comprising the following steps:

-embedding or surrounding the helical basic shape protrusion with a molding compound;

-curing the moulding compound;

-removing the helical basic shape male part from the cured moulding compound in order to produce a helical basic shape female part;

-incorporating a conical gap into the helical basic shape female part, wherein the conical gap is incorporated coaxially with a central longitudinal axis of the helical basic shape female part, and thereby producing a helical shape female part; and

-providing a conical core in the helically shaped female part.

After the core has been arranged in said helically shaped female part, the female mould for the helical nozzle is completed. A core is disposed in the helically shaped female member such that an outer surface of the core is partially supported on an inner wall of the helically shaped female member. These are usually parts of the inner wall of the helically shaped female part, which have been previously created when the conical gap is incorporated into the helically shaped female part. To manufacture the spiral nozzle, the resulting female mold may be cast with the desired material (e.g., plastic, ceramic composite, or metal) for the spiral nozzle. In the manufacture of spiral nozzles by investment casting, a female mold is first cast with wax to create a dimensionally accurate pattern. The pattern is then covered and the spiral nozzle itself is then fabricated in a lost wax casting process. A significant advantage of the method according to the invention is that initially a spiral-shaped basic shape projection is produced, which is then embedded in the molding compound or surrounded by the molding compound. The helical basic shape projection is relatively stable because it still has a core, in contrast to the finished helical nozzle. Thus, the helical basic shape male may be manufactured, for example, from a metal material that is easy to machine (in particular brass or aluminum), or from a plastic material (in particular by 3D printing). The spiral-shaped female part is manufactured only after the conical gap has been incorporated into the spiral-shaped female part, which defines the spiral nozzle to be manufactured in terms of its dimensions. Dies for spiral nozzles with different output data (e.g. different throughput rates) can then be established by using the same spiral basic shape male and spiral basic shape female, since only the size of the conical gap and the size of the conical core need to be modified for achieving different output data. For example, liquid metals that solidify by solidification can also be used as molding compounds in the context of the present invention. In the context of the present invention, a geometry that tapers from a larger cross-section to a smaller cross-section without an intervening enlargement of the cross-section is referred to as a taper.

Thus, in the case of the method according to the invention, the internal geometry of the spiral nozzle is defined by the conical gap and the conical core. Modification of the dimensions of the conical gap and the conical core results in modification of the output data of the helical nozzle.

In a development of the invention, the outer dimensions of the conical portion of the conical core correspond to the dimensions of the conical gap.

In this way it can be ensured that the core bears on the part of the inner wall of the helically shaped female part which has been created when the conical gap was incorporated.

In a development of the invention, modifications of the dimensions of the conical gap and of the conical core are provided in order to produce spiral nozzles with different output data.

The dimensions of the spiral basic shape female element are not modified herein. Thereby, it is possible to manufacture molds for spiral nozzles having different output data using the same spiral basic shape male member or spiral basic shape female member, respectively.

In a development of the invention, the driving out of the helical basic shape male from the cured moulding compound is performed around the central longitudinal axis of the helical basic shape male when the helical basic shape female is removed.

Such a drive-out is enabled in which the helical basic shape projection is not destroyed, the cross section of the helical basic shape projection never becoming wider (and uniform if this happens) in the direction towards its tip, but generally decreasing. Thereby, the helical basic shape protrusion can also be ejected from the inelastically cured moulding compound. The helical basic shape male also has two helical surfaces, one of which is directed towards the tip and the other is directed away from the tip, the two helical surfaces defining between them a helix of the helical basic shape male. The two helical surfaces are arranged such that the spacing between the two helical surface portions (which adjoin the same gap between the two helical portions) is at least partially uniform towards the tip and/or increases at least partially towards the tip, wherein the helical surface portions face each other. In other words, the spacing between the helical portions either increases or is uniform, but not decreasing, towards the tip. Thereby also enabling the ejection of the helically shaped female part from the cured non-elastic moulding compound. As already explained, it is also advantageous to drive the helical basic shape projection out of the cured moulding compound, because, in contrast to the finished helical nozzle, it does not yet have any conical gap instead of the core of the helix. Thus, the helix of the helical basic shape male still has a filled core or central portion which stabilizes the helical basic shape male.

The problem underlying the invention is also solved by a helical basic shape male for manufacturing a mould for a helical nozzle, wherein the helical basic shape male has a conical outer contour and two helical surfaces extending so as to be spaced apart from each other, the two helical surfaces converge in each case in a helical manner and within the conical outer contour towards the tip of the helical basic-shape male element, wherein the helical surfaces define therebetween a helix of the helical basic shape male member, and wherein a first helical surface faces the tip and a second helical surface faces away from the tip, in the helical basic shape projection, the spacing between two helical surface portions adjoining the gap between two helical portions and facing each other is at least partially uniform towards the tip and/or at least partially increases towards the tip.

As already explained, this makes it possible to unscrew or drive the helical basic shape projection from the cured molding compound without destroying it. This applies even when the cured molding compound is not elastomeric. In this context, the spacing between the helical surface portions is measured on the tapered generatrix as well as perpendicular to the tapered generatrix of the outer contour. The spacing may also be measured on a line parallel to the bus bar. The measurement of the spacing is advantageously performed in a plane enclosing the central longitudinal axis.

In a development of the invention, the angle enclosed by the helical surface portions adjoining the gap between the two helical portions and facing each other increases at least partially towards the tip, or is at least partially uniform towards the tip, wherein the angle is measured in a plane arranged radially with respect to the central longitudinal axis.

This also facilitates the unscrewing or driving of the helical basic-shape projections from the cured moulding compound.

In a development of the invention, the spiral body transitions towards the central longitudinal axis into a central portion which surrounds the central longitudinal axis and extends up to the tip, wherein the transition between the spiral surface and the central portion is in particular rounded.

As already explained, the central portion of the spiral-shaped basic shape projection contributes to a high stability of the spiral-shaped basic shape projection. The rounded transitions between the helical surfaces and the central portion facilitate the ejection of the helical basic shape protrusions from the cured molding compound.

The problem to be solved by the invention is also solved by a spiral-shaped nozzle having at least partly a coreless spiral, wherein the spiral has two spiral surfaces extending spaced apart from each other and defining a spiral between them, the spiral converging towards a tip of the spiral-shaped nozzle and being arranged within a conical outer contour, wherein a first spiral surface faces the tip and a second spiral surface faces away from the tip, in which spiral-shaped nozzle the spacing between two spiral surface portions abutting a gap between the two spiral portions and facing each other is at least partly uniform towards the tip and/or increases at least partly towards the tip.

The spiral of the spiral nozzle according to the invention is typically coreless, except for the tip. The spacing is measured on a generatrix of the conical outer contour of the spiral body and a generatrix perpendicular to the conical outer contour, or on a line parallel to the generatrix. The spacing may be measured in a plane enclosing the central longitudinal axis.

Drawings

Further features and advantages of the invention emerge from the claims and from the following description of preferred embodiments of the invention in conjunction with the drawings. In the drawings:

FIG. 1 shows a side view of a spiral nozzle according to the present invention;

FIG. 2 shows a side view of a spiral basic shape male part, which is used in the method according to the invention for manufacturing a female mold for the spiral nozzle of FIG. 1;

FIG. 3 shows a cross-sectional view of the spiral basic shape male member of FIG. 2;

FIG. 4 shows a cross-sectional view of a helical basic shape female part manufactured by embedding the helical basic shape male part of FIGS. 2 and 3 in a molding compound;

FIG. 5 shows a view of the spiral basic shape female member of FIG. 4 from obliquely above;

FIG. 6 shows a cross-sectional view of a helically shaped female part created by incorporating a tapered gap into the helically shaped female part of FIGS. 4 and 5;

FIG. 7 shows a cross-sectional view of a die used to make the spiral nozzle of FIG. 1;

FIG. 8 shows a container of the mold of FIG. 7;

FIG. 9 shows a cross-sectional view of the container of FIG. 8 in an assembled state with the helically shaped female member of FIG. 6; and

fig. 10 shows a view from obliquely above of the helically shaped female part of fig. 9 and a container enclosing the helically shaped female part.

Detailed Description

Fig. 1 shows a spiral nozzle 10 according to the invention. The helical nozzle 10 has a helical body 12, the helical body 12 having a conical outer profile tapering towards a tip 14. In the case of the illustrated spiral nozzle 10, the outer contour is not strictly conical, but extends in the last two spiral turns in front of the tip to be inclined more severely towards the central longitudinal axis 16 than the purely conical contour. The tip 14 is slightly flattened, wherein this is not mandatory in the context of the present invention. The spiral 12 is embodied to be coreless such that a conical gap 18 is provided within the spiral 12. The tapered gap terminates in region 20. The liquid to be sprayed is supplied to the spiral nozzle 10 through the conical gap 18 and through the connector 22. In the context of the present invention, any profile that tapers from a larger cross-section to a smaller cross-section without enlarging the cross-section in an intervening manner is referred to as a taper.

The spiral 12 is defined by a first helical surface 24 and a second helical surface 26, and is further defined by an outer surface 28 and an inner surface 30. The inner surface 30 partially defines the tapered gap 18. The first helical surface 24 extends up to the tip 14 and herein faces away from the tip 14 and is thus directed upwards in fig. 1. The second helical surface 26 likewise extends up to the tip 14 and herein faces the tip 14. The two

helical surfaces

24, 26 terminate at the connector region 22 and transition into the cylindrical tubular connector region 22. In the context of the present invention, the connector area does not necessarily have to be implemented in a cylindrical manner. The connector region 22 has a connector thread 32, which in the case of the illustrated embodiment is configured as an external thread, and a non-circular outer contour region 34. The non-circular outer contoured region 34 is used for engaging a tool to tightly screw the helical nozzle 10 onto a liquid conducting wire. Flanges may also be provided instead of external threads and generally hexagonal outer profile regions.

The helical surface 24 facing away from the tip 14 extends to be unevenly sloped and thus does not have a constant gradient. The discharge of liquid from the gap 18 during operation of the spiral nozzle 10 can be controlled by the design of the first spiral surface 24. In the case of the embodiment shown, the second helical surface 26 likewise does not extend through a constant gradient. In the context of the present invention, both helical surfaces may have a constant gradient.

The spacing between the two

helical surfaces

24, 26, measured across the gap between the individual helical portions, increases towards the tip 14 or is at most uniform. This will also be explained in detail by means of the illustration of fig. 3.

The angle enclosed by the two

helical surfaces

24, 26 on opposite portions in the direction of the central longitudinal axis 14 is either uniform or increases towards the tip 14. This will also be explained in detail by means of the illustration of fig. 3.

Fig. 2 shows a helical basic-shape male member 40 for manufacturing the helical nozzle 10 of fig. 1. The helical basic shape male member 40 has geometrically the same outer profile as the outer profile of the helical nozzle 10 of fig. 1, except that in the case of the helical basic shape male member 40, the connector thread 32, the non-circular outer profile region 34 and the conical gap 18 are absent. However, shrinkage may occur during the manufacturing process, so that the helical basic shape projection and the helical nozzle optionally have slightly deviating outer contours. Instead of the gap 18, the helical basic shape projection 40 is provided with a core or central portion which completely fills the inner space defined by the gap 18 in the case of the helical nozzle 10.

Thus, if the helical basic shape projection 40 made of the same material is to be compared with the helical nozzle 10, the helical basic shape projection is relatively stable with respect to the helical nozzle 10. As already explained, the core region 42 indicated by a dot-dash line in fig. 2 contributes thereto. However, the core region 42 is composed of the same material as the rest of the helical basic shape male member 40.

To manufacture the female mold for the spiral nozzle 10 of fig. 1, the spiral-shaped basic shape male member 40 is embedded in the molding compound, for example, by over-casting with liquid metal, and then, after the molding compound is cured (in particular, the metal is solidified), the spiral-shaped basic shape male member is removed from the cured molding compound. This can be performed by ejecting the spiral-shaped basic shape protrusion from the cured molding compound (see also fig. 4). Initially, which facilitates the driving out of the helical basic shape projection 40, the helical basic shape projection has a central portion which surrounds the central longitudinal axis 16 and which extends further in the direction towards the tip 14 than the core region 42 and has a larger diameter than the core region 42 and considerably reinforces the spiral 12 of the helical basic shape projection 40. As in the case of the helical nozzle 10 of fig. 1, the two

helical surfaces

24, 26 also have a spacing between the two helical surface portions that are contiguous with the gap between the two helical portions and that face each other, the spacing being at least partially uniform towards the tip 14 and/or increasing at least partially towards the tip 14. Thereby, the helical basic shape protrusion 40 can also be ejected from the non-elastic cured moulding compound. The angle between the two

helical surfaces

24, 26 enclosed by the helical surface portions adjoining the gap between the two helical portions and facing each other is also at least partially uniform or at least partially increasing, but not decreasing, towards the tip 14. This also makes it possible to eject the helical basic-shape projections from the cured molding compound. The

helical surfaces

24, 26 transition into the core of the helical basic shape male 40 by means of a rounded transition 44. The stability of the helical basic shape projection 40 is thereby increased.

Fig. 3 shows a cross-sectional view of the helical basic shape male member 40 of fig. 2, wherein the cross-sectional plane contains the central longitudinal axis 16. It can be seen that the spacing between the mutually opposed helical surface portions of the

helical surfaces

26, 24 adjacent the gap increases towards the tip 14. It can be readily seen that the spacing x in the first turn of the spiral body 12, which starts from the end of the spiral-shaped basic-shape projection 40 with the larger diameter in fig. 3, thus opposite the tip 14, is smaller than the spacing y measured between the spiral surfaces 24, 26 on the second turn. In the context of the present invention, the interval x should not be greater than the interval y.

The angle α measured between the mutually opposed helical surface portions of the

helical surfaces

24, 26 on the first turn of the spiral body 12 is also less than the angle β measured on the mutually opposed helical surface portions of the

helical surfaces

24, 26 in the second turn of the spiral body 12 in the context of the present invention, the angle α should not be greater than the angle β.

It can also be easily seen in fig. 3 that the cross-section of the spiral-shaped basic-shape projection 40 is at most uniform in the direction towards the tip 14 (in particular, in the upper end in fig. 3, which then defines the connector region 22 of the spiral-shaped nozzle 10), but then decreases towards the tip 14. Only the envelope or outer contour of the helical basic-shape male 40 is considered in this context, and the cross-sectional reduction between the individual helical portions is not considered.

Fig. 4 shows a spiral-shaped basic shape female part 50, which is produced after embedding the spiral-shaped basic shape male part 40 of fig. 2 and 3 in a molding compound, curing the molding compound and ejecting the spiral-shaped basic shape male part 40 from the cured molding compound. The female spiral basic shape element 50 has an inner contour which corresponds to the outer contour of the male spiral basic shape element 40.

Fig. 5 shows a view from obliquely above onto the spiral-shaped basic shape female element 50 of fig. 4.

The spiral-shaped basic-shape female element 50 does not necessarily have a circular outer contour and in the case of the illustrated embodiment is provided with a cubical outer contour.

In the case of the method according to the invention, the conical gap 18 is then incorporated so as to be parallel to the central longitudinal axis 14 in the spiral-shaped basic-shape female part of fig. 4 and 5, so that a spiral-shaped female part 60 shown in the sectional view in fig. 6 results. The gap 18 is geometrically identical or at least geometrically similar in its dimensions to the tapered gap 18 of the finished helical nozzle 10 (see fig. 1) because of the possibility of selective shrinkage during the manufacturing process. In the case of the illustrated embodiment, the gap 18 is configured in the shape of a truncated cone and terminates just forward of the tip 14 in a region 20 (see fig. 1). However, in the context of the present invention, the gap 18 may also be embodied to be only conical, and therefore does not have to strictly follow the shape of a truncated cone or a cone.

The output data of the spiral nozzle 10 is defined by the size of the gap 18. For example, when the gap 18 is selected to be larger in diameter, the completed spiral nozzle 10 will have a higher throughput rate at a defined liquid pressure. Conversely, throughput may be reduced by reducing the diameter of the gap 18. For example, the profile of the gap 18 and the length of the gap 18, respectively, are further parameters.

Thus, a matrix for spiral nozzles 10 with different output data can be produced by the method according to the invention. These different output data are achieved in a very simple manner by modifying the size of the gap 18.

The helically shaped female part 60 of fig. 6 is open towards the top and the bottom. These openings are then used for inserting the core (see fig. 7) and for filling with a free-flowing material for manufacturing the spiral nozzle 10, for venting the mould or for cleaning the mould.

Fig. 7 shows a cross-sectional view of a completed die 70 for the spiral nozzle 10 of fig. 1. A partially frustoconical shaped core 72 has now been incorporated into the gap 18 of the helically shaped female part 60. The outer dimension of the frustoconical portion of the core 72 corresponds to the inner dimension of the gap 18 of the helically shaped female member 60. Thus, in the region of the helically shaped recess 60, the outer wall of the core 72 bears on the inner wall portion of the helically shaped recess 60 which has been produced by the incorporation of the gap 18.

In fig. 7, a connector mold portion 74 has been placed on top of the helically shaped female member 60, the connector mold portion 74 defining a mold between the core 72 and the connector mold portion 74 for the connector threads 32 and for the generally non-circular outer profile region 34 of the connector region 22 (see fig. 1). Between the core 72 and the helically shaped female part 60 a female die is defined which is filled with a free flowing material and which then induces the configuration of the spiral 12 of the helical nozzle 10 of fig. 1.

A closing plate 76 has been placed on the bottom of the spiral-shaped female element 60, which closes the lower opening of the spiral-shaped female element 60 in fig. 7.

The helically shaped female part 60 is surrounded by a container 78, the container 78 being configured such that a surrounding cooling duct 80 is created between the container 78 and the outer wall of the helically shaped female part 60.

When the spiral nozzle is made of plastic, ceramic or a suitable metal, the mold 70 may be used directly to make the spiral nozzle 10 of fig. 1. When the spiral nozzle 10 is manufactured by an investment casting method or a lost wax casting method, the mold 70 is used to manufacture a wax pattern, then the wax pattern is surrounded with sand or ceramics so as to manufacture a further mold, then the wax pattern is displaced from the further mold, and then the further mold is broken after metal casting has been performed. A plurality of wax patterns are typically assembled to form a tree, which is then surrounded by sand or ceramic. The wax pattern differs from the finished spiral nozzle in size only by the shrinkage that occurs when the liquid metal in the mold solidifies.

Fig. 8 shows the container 78 of fig. 7 in isolation. The vessel 78 has a helically circumferential groove on its inner wall which then in combination with the helically shaped recess 60 (see fig. 9) defines a circumferential cooling duct 80.

Fig. 10 shows the container 78 and the helically shaped female member 60 of fig. 9 in a view from obliquely above. The helically shaped female member 60 has a square outer cross-section. The container 78 has a correspondingly adapted inner bore. The cooling duct 80 (see fig. 9) thus also extends in the form of a spiral with a square cross section.

Claims

1. A method for manufacturing a female mold for a spiral nozzle, the method comprising the steps of:

-curing the moulding compound;

-providing a conical core in the helically shaped female part.

2. The method of claim 1, wherein an outer dimension of the tapered portion of the tapered core corresponds to a dimension of the tapered gap.

3. A method according to claim 1 or 2, characterized in that the dimensions of the conical gap and the conical core are modified in order to manufacture spiral nozzles with different output data.

4. Method according to at least one of the preceding claims, characterized in that, when removing the helical basic shape projection, ejecting the helical basic shape projection from the solidified moulding compound is performed around a central longitudinal axis of the helical basic shape projection.

5. A helical basic shape male for manufacturing a mold for a helical nozzle, wherein the helical basic shape male has a conical outer contour and two helical surfaces, said two helical surfaces extending so as to be spaced apart from one another, said two helical surfaces converging in each case in a helical manner and within the conical outer contour towards the tip of the helical basic-shape male element, wherein the helical surface defines a helix of the helical basic shape male member therebetween, and wherein the first helical surface faces towards the tip and the second helical surface faces away from the tip, characterized in that the spacing between two helical surface portions adjoining the gap between the two helical portions and facing each other is at least partially uniform towards the tip and/or at least partially increasing towards the tip.

6. The helical basic shape male member of claim 5, wherein an angle enclosed by two helical surface portions adjoining a gap between two helical portions and facing each other is at least partially coincident towards the tip, or at least partially increases towards the tip, wherein the angle is measured in a plane arranged radially with respect to a central longitudinal axis.

7. The helical basic shape male member of claim 5 or 6, wherein the helical body transitions toward the central longitudinal axis to a central portion that surrounds the central longitudinal axis and extends up to the tip.

8. The helical basic shape male of claim 7, wherein a transition between the helical surface and the central portion is rounded.

9. A helical nozzle having at least in part a coreless screw, wherein the screw has two helical surfaces extending spaced apart from each other and defining a screw therebetween, the screw converging towards a tip of the helical nozzle and being disposed within a tapered outer profile, wherein a first helical surface faces towards the tip and a second helical surface faces away from the tip, characterised in that the spacing between two helical surface portions abutting a gap between two helical portions and facing each other is at least partially uniform towards the tip and/or increases at least partially towards the tip.

10. The helical nozzle as defined in claim 9 wherein an angle enclosed by two helical surface portions abutting a gap between two helical portions and facing each other is at least partially coincident towards said tip or at least partially increases towards said tip, wherein said angle is measured in a plane disposed radially relative to said central longitudinal axis.