U.S. patent application number 12/925858 was filed with the patent office on 2011-05-12 for high pressure nozzle and method for the manufacture of a high pressure nozzle.
This patent application is currently assigned to LECHLER GMBH.. Invention is credited to Albert Fecht, Juergen Frick, Boris Schmidt.
Application Number | 20110110811 12/925858 |
Document ID | / |
Family ID | 39650949 |
Filed Date | 2011-05-12 |
United States Patent
Application |
20110110811 |
Kind Code |
A1 |
Fecht; Albert ; et
al. |
May 12, 2011 |
High pressure nozzle and method for the manufacture of a high
pressure nozzle
Abstract
High pressure nozzle and method for the manufacture of a high
pressure nozzle. The high pressure nozzle has a jet director
located within a supply channel leading to a discharge opening. In
an area directly surrounding the supply channel median longitudinal
axis, the jet director has a free flow cross-section.
Inventors: |
Fecht; Albert; (Riedrich,
DE) ; Frick; Juergen; (Weinstadt-Endersbach, DE)
; Schmidt; Boris; (Esslingen, DE) |
Assignee: |
LECHLER GMBH.
|
Family ID: |
39650949 |
Appl. No.: |
12/925858 |
Filed: |
November 1, 2010 |
Related U.S. Patent Documents
|
|
|
|
|
|
Application
Number |
Filing Date |
Patent Number |
|
|
12152362 |
May 14, 2008 |
7841548 |
|
|
12925858 |
|
|
|
|
60958990 |
Jul 10, 2007 |
|
|
|
Current U.S.
Class: |
419/36 |
Current CPC
Class: |
B21B 45/0233 20130101;
B21B 45/08 20130101; B22F 7/062 20130101; B22F 3/225 20130101; B05B
15/40 20180201; Y10T 29/49433 20150115; B05B 1/04 20130101; B05B
1/3402 20180801; B22F 5/106 20130101; B05B 1/042 20130101 |
Class at
Publication: |
419/36 |
International
Class: |
B22F 1/00 20060101
B22F001/00; B22F 3/12 20060101 B22F003/12 |
Foreign Application Data
Date |
Code |
Application Number |
May 15, 2007 |
DE |
102007024247.8 |
Claims
1.-17. (canceled)
18. Method for the manufacture of a high pressure nozzle for
descaling steel products, the method comprising the following
steps: mixing metal powder with plastic binder to obtain a mixture,
die casting the mixture in a mold to obtain a casted mixture in the
general shape of at least one part of a nozzle, removing the binder
from the casted mixture by chemical and/or thermal processes,
forming an intermediate product, and sintering the intermediate
product after the step of removing the binder.
19. Method according to claim 18, wherein the at least one part is
a plurality of parts and the method further comprises the step of
assembling the parts prior to the step of sintering of the
intermediate products.
20. Method according to claim 18, wherein the metal powder at least
partly contains hard metal powder.
21. Method according to claim 18, wherein the manufactured high
pressure nozzle has at least one filter and a jet director forming
a filter and jet director component, assembled from at least two
individual parts which are permanently interconnected by
sintering.
22. A nozzle manufactured according to the method of claim 19.
23. Method according to claim 21, wherein the jet director is
within a supply channel leading to a discharge opening, the jet
director having a free-flow cross-section in an area directly
surrounding a central longitudinal axis of the supply channel, the
filter having entrance slots upstream of the jet director and
oriented radially relative to the central longitudinal axis, the
filter further comprising a filter cap and a main filter part, the
filter cap and the main filter part being interconnected by
sintering.
24. Method according to claim 18, wherein the step of die casting
comprises die casting the mixture in molds to obtain casted
mixtures in the shapes of a filter cap and a main filter part which
defines a jet director, the step of forming comprises forming the
filter cap and the main filter part as individual intermediate
products following the step of removing the binder, the method
further including assembling the individual intermediate products
to one another and sintering the assembled intermediate products to
one another to permanently interconnect the products to one another
and form a combined jet director and filter product.
25. Method according to claim 24, wherein the step of removing the
binder from the casted mixtures yields porous intermediate products
having gaps between individual powder particles, and said step of
sintering permanently interconnects the intermediate products to
one another and fills the gaps.
26. Method according to claim 18, wherein the step of die casting
comprises die casting the mixture in molds to obtain casted
mixtures in the shapes of a filter cap, a main filter part which
defines a jet director and a line part, the step of forming
comprises forming the filter cap, the main filter part and the line
part as individual intermediate products following the step of
removing the binder, the method further including assembling the
individual intermediate products to one another and sintering the
assembled intermediate products to one another to permanently
interconnect the products to one another and form a combined jet
director and filter product.
27. A method of manufacturing a nozzle comprising the steps of:
mixing a metal powder with a binder to create a feedstock; placing
the feedstock into a casting mold; casting the feedstock in the
casting mold to create a plurality of first intermediate
components; removing the binder from the first intermediate
components and thereafter assembling the first intermediate
components to one another to create a second intermediate
component; and sintering the second intermediate component to
create a one-piece, unitary nozzle.
28. The method of claim 27 wherein the step of removing the binder
yields porous first intermediate components having gaps between
individual powder particles, and the step of sintering permanently
interconnects the first intermediate components of the second
intermediate component to one another.
Description
CROSS REFERENCE TO RELATED APPLICATIONS
[0001] This application is a continuation of prior U.S. application
Ser. No. 12/152,362, filed May 14, 2008, which claims the benefit
of U.S. Provisional Application No. 60/958,990, filed Jul. 10,
2007.
FIELD OF THE INVENTION
[0002] The invention relates to a high pressure nozzle with a jet
director within a supply channel to a discharge opening. The
invention also relates to a method for the manufacture of a high
pressure nozzle.
BACKGROUND OF THE INVENTION
[0003] European patent EP 792 692 B1 discloses a high pressure
nozzle for descaling steel products, which is provided with a jet
director within a supply channel to a discharge opening. The jet
director is formed in a cross-sectionally radial component and has
a cylindrical central part from which extend radially flow guidance
surfaces. To reduce the flow resistance of the jet director, in
both the upstream and downstream directions the cylindrical central
part is extended in the form of a conical tip. Upstream of the jet
director is located a filter, which is formed from a tubular
portion with a spherical cap-shaped termination and with radial
grooves for the entry of liquid. The radial grooves extend into the
spherical segmental cap of the filter. Downstream of the jet
director there is a gradual tapering of the flow channel, which
extends with decreasing taper angle to a discharge chamber in a
mouthpiece. The mouthpiece has the discharge chamber and the
discharge opening connecting onto said discharge chamber. As a
result of the very high liquid pressures with which the high
pressure nozzles are operated for descaling steel products and
which can be several 100 to 600 bar, a low flow resistance is
decisive, because pressure losses within the high pressure nozzle
either lead to a lower removal or to the need for a higher pressure
of the supply line. In addition, the shape of the flat jet or spray
produced is decisive and for achieving an excellent removal action
it should have a minimum width. Finally the high pressure nozzle is
exposed to considerable mechanical stresses, because e.g. pressure
surges in the supply line can lead to a collapse of the high
pressure nozzle filter.
[0004] The invention aims to provide an improved high pressure
nozzle.
[0005] According to the invention for this purpose is provided a
high pressure nozzle, particularly for descaling steel products,
which has a jet director within a supply channel to a discharge
opening, in which in an area directly surrounding the median
longitudinal axis of the supply channel the jet director has a free
flow cross-section.
[0006] This leads to a so-called coreless jet director, which is
characterized on the one hand by a low flow resistance and on the
other by a very good orienting or straightening action. Thus, the
jet director has a flow channel, without built-in fittings,
directly surrounding the median longitudinal axis. Compared with
conventional jet directors having a central, cylindrical component
from which flow guidance surfaces emanate radially, the inventive
jet director has a significantly reduced flow resistance, because
the flow channel directly surrounding the median longitudinal axis
of the supply channel remains free and can be used for an
unhindered through-flow. As the free cross-section available for
the flow is much larger, a significant flow resistance reduction is
obtained. The free flow cross-section can e.g. have a radius
amounting to approximately 1/5 of the internal radius of the jet
director.
[0007] According to a further development of the invention the jet
director has flow guidance surfaces extending parallel to and
towards the median longitudinal axis of the supply channel.
[0008] By means of such flow guidance surfaces oriented parallel to
the median longitudinal axis of the supply channel a good
directivity of the jet director can be obtained and a flow which
has traversed the jet director is oriented substantially fully
parallel to the median longitudinal axis downstream of the jet
director.
[0009] In a further development of the invention the flow guidance
surfaces extend radially towards the median longitudinal axis.
[0010] This leads to planar, flow guidance surfaces having a very
good orienting action with a low flow resistance.
[0011] In a further development of the invention a tapering of the
supply channel takes place downstream of the jet director.
[0012] Such a tapering or narrowing concentrates the flow and over
a short path the flow channel can be reduced to the cross-section
of the discharge chamber. According to the invention there is a
short taper and the tapering portion of the supply channel only has
roughly half to a third of the jet director length.
[0013] In a further development of the invention, downstream of the
jet director is connected to the taper a portion having a constant
cross-section, which passes into a tapering discharge chamber.
[0014] By means of such a constant cross-section portion a flow
calming can be brought about, which leads to a very good jet
quality with a low flow resistance. The constant cross-section
portion is advantageously longer than the taper down-stream of the
jet director. It has proved to be advantageous for the constant
cross-section portion to be at least twice as long as the taper
downstream of the jet director and in particular to make it seven
times as long as the taper. The discharge chamber passes into the
discharge opening from which emanates the spray jet.
[0015] In a further development of the invention upstream of the
jet director is provided a filter having entrance slots oriented
radially to the median longitudinal axis. Advantageously the
entrance slots extend parallel to the median longitudinal axis. The
filter can have a spherical segmental filter cap provided with
entrance openings parallel to the median longitudinal axis.
[0016] The entrance openings in the spherical segmental filter cap
are separated from the entrance slots, so that the spherical
segmental filter cap can have a very stable construction and can in
particular withstand any pressure surges occurring in the supply
lines. The filter cap e.g. has a circumferential collar ensuring a
high mechanical strength. The entrance slots in the filter
consequently terminate upstream of the spherical segmental filter
cap.
[0017] In a further development of the invention end boundary
surfaces of the entrance slots located on the side of the jet
director are rounded or inwardly inclined, the rounded end boundary
surfaces having a convex construction towards the median
longitudinal axis. The bottom of the entrance slots which, in the
flow direction, is located on the side of the jet director is
consequently outwardly curved or convexly constructed towards the
median longitudinal axis. Alternatively the slot bottom is inclined
inwards and is in particular conical shell section-like, the cone
tapering in the flow direction. Thus, the flow through the entrance
slots is gradually deflected towards the median longitudinal axis
in the vicinity of the slot bottom. This significantly reduces
turbulence in the vicinity of the slot bottom and there is a low
flow resistance and a flow oriented substantially parallel to the
median longitudinal axis downstream of the jet director.
[0018] In a further development of the invention the filter is
formed by means of a filter cap and a main filter part, the filter
cap and main filter part being manufactured as single components
and then permanently interconnected.
[0019] This facilitates the manufacture even of geometrically
complicated shapes in the vicinity of the filter cap and main
filter part. Following the permanent connection of filter cap and
main filter part a stable, flow-favourable filter unit is
provided.
[0020] In a further development of the invention the filter cap and
main filter part are manufactured by metal powder die casting and
are then sintered together.
[0021] Metal powder die casting makes it possible to produce
geometrically complicated shapes, which could not be produced by
mechanical working or could only be produced when involving
significant effort and expenditure. This e.g. includes the convex
construction of the end faces of the filter entrance slots oriented
towards the median longitudinal axis. Conventionally such entrance
slots are constructed by immersing a milling cutter or saw blade in
a tubular component. This generally leads to an outwardly directed,
concave construction of the end faces, which is hydraulically
unfavourable.
[0022] In a further development of the invention the main filter
part is provided with the jet director.
[0023] This makes it possible to provide a low flow-resistance
combined jet director and filter component. When manufacturing said
combined jet director and filter component by means of metal powder
die casting the inventive coreless jet director and a
flow-favourable construction of the entrance slots on the filter
can be implemented and manufactured serially. Alternatively the jet
director can also be constructed as a separate flow channel
component or can be integrated into a different nozzle component to
the filter.
[0024] In a further development of the invention the filter cap has
a circumferential collar with radially inwardly extending
projections, which engage in matching recesses of the main filter
part.
[0025] This makes it possible to implement a very stable connection
of the filter cap to the main filter part, which also allows a very
flow-favourable construction. Alternatively the main filter part
can be provided with a circumferential collar with radially
inwardly or outwardly extending projections, which then engage in
matching recesses of the filter cap. Independently of whether the
circumferential collar is provided with radially extending
projections on the filter cap or the main filter part, the
inventive advantages of a very stable, flow-favourable construction
of the connection between filter cap and main filter part can be
achieved.
[0026] In a further development of the invention the main filter
part is provided on its end adjacent to the filter cap with webs
extending parallel to the median longitudinal axis and between
which the recesses are formed. Advantageously the entrance slots
are formed between the main filter part webs.
[0027] Thus, the main filter part has circumferentially distributed
quantities of fingers or webs extending in the upstream direction
and between which the entrance slots are formed. The ends of said
webs are received and fixed by the filter cap. Following the
permanent connection of the main filter part and filter cap this
leads to a stable component. With particular advantage the filter
cap and main filter part can be manufactured by metal powder die
casting and then sintered together.
[0028] The problem of the invention is also solved by a method for
the manufacture of a spray nozzle, particularly a high pressure
nozzle for descaling steel products, in which the following steps
are provided:
mixing metal powder with plastic binder, die casting the resulting
mixture in a mould, removing the binder by chemical and/or thermal
processes and sintering the intermediate product obtained after
removing the binder.
[0029] Such a metal powder die casting method also makes it
possible to achieve very complicated geometrical shapes, which
cannot be manufactured or can only be manufactured with
considerable effort and expenditure by conventional mechanical
working. The use of die casting machines makes it possible to bring
about comparatively inexpensive manufacture in series production
quantities, which reduces costs, e.g. compared with precision
casting. It has surprisingly been found that components obtained by
metal powder die casting are sufficiently stable to withstand the
significant operating pressures of several hundred bar occurring
with high pressure nozzles for descaling steel products. Over and
above the high operating pressures, in pipelines for supplying
descaling nozzles pressure surges can occur which are a multiple of
the operating pressures. Metal powder die casting leads to sintered
components and it is initially to be expected that the sintered
components would have a brittle character and would therefore be
unsuitable for loads with extreme pressure peaks, such as occur
when operating descaling nozzles. However, tests have surprisingly
shown that the sintered parts obtained by metal powder die casting
and in the case of a corresponding design are able to withstand
these loads and stresses and also offer new possibilities for the
flow optimization of high pressure nozzles.
[0030] According to a further development of the invention the
individual components in the form of intermediate products are
assembled following binder removal and then the assembled
intermediate products are sintered.
[0031] As a result components can be manufactured integrally, e.g.
in the form of a combined jet director and filter component
including the filter cap, because following sintering the assembled
intermediate products are permanently interconnected. This offers
further possibilities for a simultaneously stable and
flow-favourable design of high pressure nozzles. Following binder
removal the intermediate product has a comparatively fragile
structure, because following binder removal the metal powder has a
porous structure. Only during sintering is the intermediate product
compacted and is then mechanically highly loadable.
[0032] In a further development of the invention the metal powder
at least partly contains hard metal powder.
[0033] It has surprisingly been found that even hard metal/carbide
parts can be manufactured by metal powder die casting. This is
particularly advantageous for the manufacture of mouthpieces of
high pressure descaling nozzles. Also in the mouthpiece area and
specifically in the area of the discharge chamber and discharge
opening this makes it possible to bring about complicated
geometrical shapes, which cannot or cannot be produced with
acceptable costs by mechanical working. Following sintering of the
hard metal powder intermediate product a hard metal component is
obtained, which is eminently suitable for use as a high pressure
descaling nozzle mouthpiece and in particular has a long service
life.
[0034] In a further development of the invention the high pressure
nozzle has at least one filter and a jet director in a combined
filter and jet director component, which is assembled from at least
two individual parts, which are permanently interconnected by
sintering.
BRIEF DESCRIPTION OF THE DRAWINGS
[0035] Further features and advantages of the invention can be
gathered from the claims and the following description of a
preferred embodiment of the invention, as well as the attached
drawings, in which:
[0036] FIG. 1 is a perspective, cut-open view of an inventive high
pressure nozzle.
[0037] FIG. 2 is a sectional view of the high pressure nozzle of
FIG. 1.
[0038] FIG. 3 is a sectional view of a combined jet director and
filter component of the high pressure nozzle of FIG. 1.
[0039] FIG. 4 is a perspective view of a main filter part with
integrated jet director of the component of FIG. 3.
[0040] FIG. 5 is a side view of the main filter part of FIG. 4.
[0041] FIG. 6 is a view of the main filter part of FIG. 5 in the
direction of arrow VI.
[0042] FIG. 7 is a view of the main filter part of FIG. 5 along
arrow VII.
[0043] FIG. 8 is a view of the main filter part of FIG. 5 relative
to sectional plane VIII-VIII.
[0044] FIG. 9 is a larger scale view of a detail of the main filter
part of FIG. 8.
[0045] FIG. 10 is another side view of the main filter part of FIG.
4.
[0046] FIG. 11 is a sectional view of the main filter part of FIG.
10 relative to sectional plane XI-XI.
[0047] FIG. 12 is a side view of a filter cap of the component of
FIG. 3.
[0048] FIG. 13 is a view of the filter cap of FIG. 12 in the
direction of arrow XIII.
[0049] FIG. 14 is a sectional view on sectional plane XIV-XIV of
FIG. 13.
[0050] FIG. 15 is a sectional view on sectional plane XV-XV of FIG.
13.
[0051] FIG. 16 is a diagrammatic representation for illustrating
the method of the invention.
DETAILED DESCRIPTION
[0052] The perspective sectional view of FIG. 1 shows an inventive
high pressure nozzle 10 for descaling steel products. The high
pressure nozzle 10 is installed in a tubular connection nipple 12
and is secured in the latter by means of a box nut 14. The high
pressure nozzle 10 has a combined filter and jet director component
16 screwed into a nozzle housing 18. Into nozzle housing 18 is
inserted a mouthpiece 20, which at its downstream end defines a
discharge opening 22. The tubular connection nipple 12 is connected
to a not shown nozzle beam into which projects a filter 24 of high
pressure nozzle 10. Liquid entering the high pressure nozzle 10
through filter 24 flows via a jet director 26 and ultimately
reaches the mouthpiece 20, passing out of the discharge opening 22
in the form of a flat jet or spray. Mouthpiece 20 is sealed against
nozzle housing 18 by means of a circumferential soldered metal
joint 28.
[0053] FIG. 1 clearly shows that the jet director 26 leaves free a
flow channel directly surrounding a median longitudinal axis 30 of
high pressure nozzle 10. Thus, in the vicinity of jet director 26
there is a flow channel, without any built-in fittings, directly
surrounding median longitudinal axis 30. The jet director 26 has
several flow guidance surfaces extending radially towards the
median longitudinal axis 30 and which have a planar construction
and are oriented parallel to median longitudinal axis 30. By means
of jet director 26 the liquid entering filter 24 can be oriented
parallel to the median longitudinal axis 30. As will be explained
hereinafter and as can be seen in FIG. 1, the several flow guidance
surfaces of jet director 26 are only fixed to the outer
circumference of the jet director and project freely in the
direction of the flow channel surrounding median longitudinal axis
30.
[0054] The sectional view of FIG. 2 shows two facing flow guidance
surfaces of jet director 26 through which passes the sectional
plane. Upstream of jet director 26 is located filter 24, which is
formed from a circular cylindrical tubular portion with entrance
slots extending radially to the median longitudinal axis 30 and
which is provided with a spherical segmental filter cap.
[0055] Downstream of jet director 26 is connected a conically
tapering portion 32, which passes into a circular cylindrical
portion 34 with constant diameter. The tapering portion 32 is
shorter than jet director 26 and has approximately 1/3 to 1/2 of
the length of said jet director 26. The constant cross-section
portion 34 downstream of the tapering portion 32 is much longer
than jet director 26 and also much longer than the tapering portion
32. In the embodiment shown the constant cross-section portion 34
is roughly three times as long as the jet director 26 and roughly
seven times as long as the tapering portion 32. It has been found
that such length dimensions of jet director 26, taper 32 and
constant cross-section portion 34 makes it possible to set flow
conditions favouring a precise shaping of an emerging flat jet 36.
Downstream of the constant diameter portion 34 is connected a
discharge chamber 38 in mouthpiece 20. The discharge chamber 38
tapers conically and ends at the discharge opening. The length of
discharge chamber 38 is roughly half that of the jet director 26
and is much less than the length of the constant cross-section
portion 34. The length of discharge chamber 38 is roughly of the
order of magnitude of taper 32 directly downstream of jet director
26.
[0056] In the case of the inventive high pressure nozzle a free
flow channel is made available for the flow and is tapered in two
stages over a relatively short path, namely on the one hand by the
tapering portion 32 directly downstream of the jet director 26 and
then, once again over a comparatively short path, by the tapering
discharge chamber 38. It has been found that such a two-stage
tapering, in each case relatively pronounced constriction of the
flow channel over a short path is hydraulically more favourable
than a very gradual taper or narrowing over a long path. In
particular, the available free cross-section by means of portion 32
over a short path is relatively markedly constricted and along the
constant cross-section, long portion 34 the flow can calm again in
order to enter very uniformly the discharge chamber 38.
[0057] The maximum free flow cross-section occurs in the vicinity
of filter 24 and is defined by the sum of the free cross-sections
of the elongated filter slots and the further filter slots in the
filter cap. An already significantly reduced flow cross-section is
present in the vicinity of the jet director 26, the flow
cross-section there resulting from the overall channel
cross-section, less the end faces of the radially positioned flow
guidance surfaces. The ratio of the free flow cross-sectional
surface at jet director 26 to the free flow cross-sectional surface
of filter 24 is advantageously 1:6 or higher.
[0058] A further reduction of the flow cross-section takes place
downstream of the jet director 26 on the cross-section of channel
27, which passes with a constant cross-section to upstream of
mouthpiece 12. The ratio of the free flow cross-sectional surface
in channel 27 to the free flow cross-sectional surface at jet
director 26 is advantageously 1:1.23 or higher.
[0059] The ratio of the free flow cross-sectional surface in
channel 27 to the free flow cross-sectional surface of filter 24 is
advantageously 1:7.44 or higher.
[0060] The free flow cross-sectional surface in channel 27 is e.g.
95 mm.sup.2 the free flow cross-sectional surface in jet director
26 is e.g. 117 mm.sup.2 and the free flow cross-sectional surface
at filter 24 is e.g. 707 mm.sup.2.
[0061] A soldered metal joint 28 sealing mouthpiece 12 against
nozzle housing 14 is provided at the upstream end of mouthpiece 12
between an inner wall of nozzle housing 14 and an annular end face
of mouthpiece 12.
[0062] The sectional view of FIG. 3 shows the combined jet director
and filter component 16 of high pressure nozzle 10 of FIG. 1.
Component 16 comprises three individual parts, which are
permanently interconnected, namely a filter cap 40, a main filter
part 42, which also has the jet director 26, and a line part 44,
which is provided with the tapering portion 32 downstream of jet
director 26 and the constant cross-section portion 34. At its
downstream end line part 44 is provided with an external thread 46
with which the line part 44 is screwed into the nozzle housing
18.
[0063] Filter cap 40 is spherical segmental and has entrance
openings 48 extending parallel to median longitudinal axis 30. The
entrance openings 48 are arranged radially on filter cap 40. The
main filter part 42 has several webs 50 extending parallel to
median longitudinal axis 30 and which are arranged around its
circumference in uniformly spaced manner. Between the webs 50 are
located entrance slots through which the liquid can enter filter
24.
[0064] FIG. 3 clearly shows that the downstream end faces 52 of the
entrance slots are rounded and are convexly curved towards the
median longitudinal axis 30. Liquid entering the entrance slots is
consequently gradually deflected towards the median longitudinal
axis 30 in the vicinity of the downstream end faces of the entrance
slots. This keeps low the turbulence in the vicinity of end faces
52 and leads to a low flow resistance and uniform flow.
[0065] FIG. 3 also clearly shows that the planar flow guidance
surfaces 54 of jet director 26 extending radially towards the
median longitudinal axis 30 leave free a flow channel 56 without
built-in fittings directly surrounding said median longitudinal
axis.
[0066] The filter cap 40, main filter part 42 with jet director 26
and line part 44 are manufactured as individual parts by metal
powder die casting and then, after removing a thermoplastic binder,
are assembled as individual intermediate products and then
sintered. Following sintering filter cap 40, main filter part 42
and line part 44 are permanently interconnected and form the highly
loadable, combined jet director and filter component 16.
Manufacture by metal powder die casting will be described in detail
hereinafter.
[0067] FIG. 4 perspectively shows the main filter part 42 of FIG.
3. In broken line form are shown the not visible details, such as
the radially oriented flow guidance surfaces 54 and concealed
entrance slots between webs 50. At the upstream end the webs 50 are
constructed with a reduced thickness, so that each web 50 has a
step 58, which serves as a stop member on engaging filter cap 40,
as can be seen in the side view of FIG. 5.
[0068] The view of FIG. 6 in the direction of arrow VI of FIG. 5
shows the jet director flow guidance surfaces 54 extending towards
the median longitudinal axis 30 and which leave free around the
latter said flow channel 56. As has already been explained, only
the radially outer end of the flow guidance surfaces 54 is
connected to the inner wall of the main filter part 42 and project
freely towards the median longitudinal axis. FIG. 6 makes it clear
that the flow guidance surfaces 54 leave free a comparatively
equally large cross-section and despite a very good straightening
effect only give rise to a limited flow resistance. All the edges
of the flow guidance surfaces 54 projecting into the flow are
rounded.
[0069] FIG. 7 is a view of the main filter part 42 in the direction
of arrow VII in FIG. 5. It is clearly possible to see the free ends
of webs 50 with in each case a step 58. Webs 50 leave between them
entrance slots extending radially towards the median longitudinal
axis and through which liquid can enter the interior of the main
filter part 42. The number of slots between the webs 5 exceeds the
number of flow guidance surfaces. In the embodiment shown there are
eight flow guidance surfaces 54 and fourteen entrance slots, which
are in each case uniformly distributed around the circumference of
the main filter part 42.
[0070] The sectional view of the main filter part 42 in FIG. 8 on
the sectional plane VIII-VIII of FIG. 5 reveals the rounded
construction of the end faces 52 of the entrance slots between the
webs 50 of filter 24.
[0071] The end faces 52 of the entrance slots are curved, as is
particularly apparent from the sectional view of FIG. 11 on
sectional plane XI-XI of 10, showing a convex construction in the
direction of the median longitudinal axis 30. Moreover the
transitions between end faces 52 and the lateral boundaries of webs
50 defining the entrance slots are rounded, as is particularly
clear in FIG. 9. The liquid entering through the entrance slots is
deflected towards the median longitudinal axis 30 accompanied by
limited turbulence and therefore low flow losses. The free edges of
the flow guidance surfaces 54 of jet director 26 are also rounded,
as can be seen in FIGS. 6, 7 and 11.
[0072] FIG. 12 is a side view of filter cap 40, which is
constructed in essentially spherical segmental form and has radial
entrance openings 48 around median longitudinal axis 30 and
extending parallel to the latter. Through said entrance openings 48
liquid can enter the interior of the filter and on entry is already
oriented parallel to the median longitudinal axis 30. Filter cap 40
has an indexing slot 60, which facilitates the angularly correct
mounting of filter cap 40 on main filter part 42.
[0073] FIG. 13 is a view of filter cap 40 along arrow XIII in FIG.
12. It can be seen that the filter cap 40 has a circumferential
collar 62 with several projections 64 extending radially towards
the median longitudinal axis 30. Between each of the projections 64
is formed recesses 66 for receiving the free ends of webs 50 of
main filter part 42. The thickness of webs 50 corresponds to the
wall thickness of filter cap 40 and therefore the radial dimension
of projections 64, plus the thickness of collar 62, i.e. the length
from the outer wall of filter cap 40 to the inner wall in the
vicinity of a projection 64. As was already explained relative to
FIG. 5, the thickness of the free ends of webs 50 is reduced. Thus,
on mounting the filter cap the free ends 59 engage in recesses 66
and the free ends 59 are in this way matched to the dimensions of
recesses 66, so that an inner wall of the webs 50 in the engaged
state of cap 40 is aligned with the inner wall of cap 40. Filter
cap 40 is engaged to such an extent that the circumferential collar
62 engages with its lower edge on shoulder 58 of the main filter
part 42. As the material thickness of webs 50 corresponds to the
wall thickness of filter cap 40, following the mounting of filter
cap 40 on main filter part 42 both the outer wall of webs 50 and
the outer wall of filter cap 40, as well as the inner wall of webs
50 and the inner wall of filter cap 40 are oriented in an aligned
manner to one another. This can be gathered from the sectional view
of FIG. 3 of the assembled, combined jet director and filter
component 16. Thus, in the assembled state of filter cap 40 and
main filter part 42 there are only very narrow gaps between filter
cap 40 and main filter part 42.
[0074] Advantageously both filter cap 40 and the main filter part
42 are manufactured by metal powder die casting and are sintered in
the assembled state following binder removal. As a result of
sintering the filter cap 40 and main filter part 42 are permanently
connected and the narrow gaps still present after assembly are
filled, so that after filtering there is an integral, substantially
gapless component.
[0075] FIG. 14 is a sectional view on sectional plane XIV-XIV of
FIG. 13 and FIG. 15 is a sectional view on sectional plane XV-XV of
FIG. 13. FIGS. 14 and 15 show that the wall thickness of filter cap
40 as from collar 62 gradually decreases from its apex, i.e. the
intersection of median longitudinal axis with the wall of filter
cap 40. As a result of such a construction the length of the
entrance slots 48 parallel to median longitudinal axis 30 can be
kept as short as possible, which is advantageous for a low flow
resistance and at the same time filter cap 40 can be made extremely
stable, so that it also withstands severe pressure surges during
the operation of the inventive high pressure nozzle.
[0076] The diagrammatic view of FIG. 16 illustrates the inventive
method for the manufacture of a high pressure nozzle by metal
powder die casting.
[0077] In a first method step 70 metal powder is mixed with a
thermoplastic binder. The metal powder can e.g. be a hard metal
powder. The resulting mixture is also referred to as feedstock.
[0078] In a second step 72 the thus obtained mixture is brought
into a die casting mould. Conventional die casting machines are
used, because as a result of the thermoplastic binder the mixture
has plastic-like properties and is suitable for die casting. The
intermediate product obtained after die casting is referred to as
the green component.
[0079] The following step 74 involves binder removal and during
step 74 the thermoplastic binder is removed from the intermediate
product using suitable processes. They can e.g. be thermal or
chemical processes. Following binder removal an intermediate
product results which has a comparatively porous structure, in
which there are gaps between the individual metal powder particles
which were originally filled by the thermoplastic binder. The
intermediate product obtained after binder removal is also referred
to as a brown component.
[0080] Following binder removal individual parts can be assembled
in a step 76. As described, filter cap 40, main filter part 42 and
jet director 26 and line part 44 are separately manufactured by
metal powder die casting and are assembled following binder
removal. The line part 44 can also be manufactured as a standard
lathe work and then assembled with the binder-removed intermediate
products, namely filter cap 40 and main filter part 42.
[0081] In the assembled state of the intermediate products they are
sintered in a step 78. Sintering takes place by a heat treatment
process. After sintering the material characteristics of the
resulting end product are comparable with those of solid materials.
The assembled individual parts, specifically filter cap 40, main
filter part 42 and feedline part 44 are permanently interconnected
by the sintering step 78 and any gaps present between said
individual parts disappear. The outer and inner walls of the
combined jet director and filter component 16 run in
smooth-surfaced manner without any noticeable gaps, which is
advantageous for a low flow resistance.
[0082] In a final step 80 the sintered together components, i.e.
the combined jet director and filter component 16, can undergo
reworking or surface-treatment. Thus, the accessible surfaces can
e.g. be line polished in order to reduce the flow resistance.
[0083] The combined jet director and filter component manufactured
by metal powder die casting can have a flow-favourable and at the
same time high strength construction. The use of metal powder die
casting consequently gives rise to surprising improvements compared
with conventional high pressure nozzles.
* * * * *