Note: Descriptions are shown in the official language in which they were submitted.
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CONNECTION BETWEEN A PLASMA TORCH WEARING PART AND A
PLASMA TORCH WEARING PART HOLDER, PLASMA TORCH WEARING
PART AND PLASMA TORCH WEARING PART HOLDER
Field of the Invention
The present invention relates to a connection between a plasma torch wearing
part and
a plasma torch wearing part holder, a plasma torch wearing part and a plasma
torch
wearing part holder.
Background of the Invention
Plasma torches are known, which comprise a plasma torch shaft and a plasma
torch
head, which can be interconnected by a quick-change closure. The plasma torch
head
contains the plasma torch parts which, during operation, rapidly wear and must
frequently be replaced. These are in particular the electrode, nozzle, nozzle
protection
cap and gas guidance part, particularly the plasma gas guidance part. However,
also
when there are changes in the uses of the plasma method, e.g. between the
cutting of
structural steel and the cutting of high grade steel or when changing the use
from
cutting to welding or vice versa, the replacement of one electrode, nozzle,
nozzle
protection cap, gas guidance part, etc. for another may be necessary. In order
to
rapidly implement this, a quick-change possibility is appropriate.
To avoid damage or e.g. for producing correct supply connections, the quick-
change
possibility must provide a clear, radial positioning or a positioning along
the
circumference of the wearing parts.
The problem of the invention is to provide such a quick-change possibility for
the
wearing parts of a plasma torch.
Summary of the Invention
According to the invention this problem is solved by a connection between a
plasma
torch wearing part and a plasma torch wearing part holder, characterized in
that either
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the plasma torch wearing part holder or the plasma torch wearing part has on
its
connecting side a first cylinder wall with an outer surface and a circular
ring surface,
as well as an external diameter D41 a and the other from among the plasma
torch
wearing part holder and the plasma torch wearing part has on its connecting
side a
second cylinder wall with an inner surface and an internal diameter D52, where
D51 >
D41a and npro radial projections and ndep radial depressions run around the
inner
surface, in which npro, ndep z 0 and n.,, + ndep - Z 5, and on the outer
surface is
provided an equal number of in particular corresponding depressions or
projections
engaging therewith, and in the case of n = 5 the sum of two adjacent midpoint
angles
by which the projections or depressions or a projection and a depression are
displaced
relative to one another is not z 180 and the five midpoint angles differ, or
in the case
of n > 5 the sum of two adjacent midpoint angles by which the projections or
depressions or a projection and a depression are displaced relative to one
another is
not Z 180 and the n > 5 midpoint angles differ or at least two of the n > 5
midpoint
angles are of the same magnitude and then in each case the sum of the twice
occurring
midpoint angles and the midpoint angles adjacent thereto on either side is <
180 .
The problem is also solved by a plasma torch wearing part, characterized in
that on its
connecting side it has a cylinder wall with an outer surface and a circular
ring surface,
ndep radial depressions and nPro radial projections passing round the outer
surface,
where ndep, npr z0 and ndep + npro Z 5, and in the case of n = 5 the sum of
two adjacent
midpoint angles by which the projections or depressions or a projection and a
depression are displaced relative to one another is not z 180 and the five
midpoint
angles differ, or in the case of n > 5 the sum of two adjacent midpoint angles
by which
the projections or depressions or a projection and a depression are displaced
relative
to one another is not 2.180' and then > 5 midpoint angles differ or at least
two of the
n > 5 midpoint angles are of the same magnitude and then in each case the sum
of the
twice occurring midpoint angles and the midpoint angles adjacent thereto on
either
side is < 180 .
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This problem is also solved by a plasma torch wearing part holder,
characterized in
that on its connecting side it has a cylinder wall with an inner surface, ,pro
radial
projections and ndep radial depressions passing round the inner surface, npro,
ndep >_ 0
and npro + ndep >_ 5, and in the case of n = 5 the sum of two adjacent
midpoint angles by
which the projections or depressions or a projection and a depression are
displaced
relative to one another is not Z 1800 and the five midpoint angles differ, or
in the case
of n > 5 the sum of two adjacent midpoint angles by which the projections or
depressions or a projection and a depression are displaced relative to one
another is
not >_ 180 and the n > 5 midpoint angles differ or at least two of the n > 5
midpoint
angles are of the same magnitude and then in each case the sum of the twice
occurring
midpoint angles and the midpoint angles adjacent thereto on either side is <
180 .
In the case of the connection, the sum of two adjacent midpoint angles (a and
0 or 0
andyoryand 8or 8and cor sand a)is x170 .
According to a special embodiment of the invention n = 5 and the sum of two
adjacent
midpoint angles (a and (3 or 0 and y or y and 8 or 8 ands ors and a) is not
repeated.
It is also conceivable for the plasma torch wearing part to have the first
cylinder wall
and the plasma torch wearing part holder the second cylinder wall.
It is also possible for the ratio of the surfaces of a projection and an
associated
depression to be in the range 1:1 to 1:4. In the case of an e.g. rectangular
slot and
nose, as shown in Figs. 6 and 7, the surface results from the product of B and
T of the
slot and nose.
It is also possible for the ratio of the surfaces of the nPro projections
and/or the ndep
depressions to be in the range 1:1 to 1:4.
In a special embodiment there are np 0 equal radial projections and ndep equal
radial
depressions.
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Advantageously the depressions are rectangular slots. However, they can also
have a
different configuration, such as e.g. triangular, arcuate, etc.
Advantageously on the inner surface of the second cylinder wall in the
connection
direction and upstream of the projections and/or depressions there is a
circumferential,
radially outwardly extending chamfer, which facilitates the introduction of
the first
cylinder wall into the second cylinder wall.
In a special embodiment of the invention npro >_ 5.
It is alternatively possible for ndep z5.
Advantageously there is a holding together device on holding together the
plasma
torch wearing part and plasma torch wearing part holder. It can e.g. comprise
a clamp
collar.
The plasma torch wearing part can be a nozzle, an electrode, a nozzle
protection cap
or a gas guidance part, particularly a plasma gas guidance part.
According to a special embodiment of the invention the plasma torch wearing
part
holder is an integral part of the plasma torch.
Alternatively a plasma torch wearing part holder is detachably connected to a
plasma
torch.
According to a special embodiment of the invention the plasma torch is a
plasma
cutting torch.
It can alternatively be a plasma welding torch.
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The invention is based on the surprising finding that as a result of the
specific number
and arrangements of projections and corresponding depressions it is possible
to obtain
a simple, rapid joining together of plasma torch wearing part and plasma torch
wearing part holder without tilting occurring. For engagement purpose the
circular
5 ring surface has to be simply engaged with the projections, i.e. brought
into a joining
position, and then turned relative to the projections until the joining
position is
reached, where in the case of an axially acting force the projections and
depressions
engage with one another. This is particularly advantageous in situations where
the
plasma torch wearing part and/or plasma torch wearing part holder are not
optically
accessible. The quick-change can so-to-speak take place blind.
The invention also provides a connection between plasma torch wearing part and
plasma torch wearing part holder with twisting protection, a limited tolerance
between
the axes of the plasma torch wearing part and plasma torch wearing part holder
and
high centricity.
Brief Description of the Drawings
Further features and advantages of the invention can be gathered from the
following
description of two embodiments relative to the attached diagrammatic drawings,
in
which:
Fig. 1 is a sectional view of a front part of a plasma torch head according to
a
special embodiment of the invention;
Fig. 2 is a perspective view of a nozzle and a nozzle holder according to a
special embodiment of the invention prior to the connection thereof;
Fig. 3 is a similar view to Fig. 2, where also water supply and return ducts
are
shown;
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Fig. 4 is is an illustration of two perspective views of an electrode and an
electrode holder prior to the connection thereof;
Fig. 5 is a similar view to Fig. 4, also showing water supply and return
ducts;
Fig. 6 is a cross-sectional view of the nozzle and nozzle holder of Fig. 2 in
the
joining position; and
Fig. 7 is a cross-sectional view of the electrode and electrode holder of Fig.
4 in
the joining position.
Detailed Description of the Invention
Fig. 1 shows a plasma torch head 1 with a nozzle cap 2, a plasma gas guidance
part 3,
a nozzle 4, a nozzle holder 5, an electrode holder 6, an electrode 7, a nozzle
protection
cap holder 8, an insulating part 8a and a nozzle protection cap 9.
Each of the Figs. 2 and 3 shows a nozzle 4 for a plasma cutting torch and a
nozzle
holder 5 for the nozzle. Nozzle 4 has a cylinder wall 41 with an outer surface
41 a and
a circular ring surface 42, the latter also fulfilling the surface of a
(second) bearing
surface. Nozzle holder 5 has a cylinder wall 51 with an inner surface 51 a and
a
bearing surface 546. The internal diameter D52 of cylinder wall 51 is larger
than the
external diameter D41 a of cylinder wall 41. Five identical rectangular slots
pass
round the outer surface 41 a, but only two of these are visible and carry the
reference
numerals 431 and 435.
Five identical, corresponding noses are located around the inner surface 51 a,
but only
three are visible and carry reference numerals 532, 533 and 534.
In the direction of nozzle 4 and upstream of noses 532 to 534, the nozzle
holder 5 has
an outwardly extending chamfer 52 facilitating the introduction of nozzle 4.
Internal
diameter D52 corresponds to the diameter on the upper edge of chamfer 52 and
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provides a clearance S = (D52-D41 a)/2. After passing chamfer 52 it tapers to
internal
diameter D51a in order to reduce the clearance S = (D51a-D41 a)/2 to almost
zero.
This brings about a simplification of positioning whilst ensuring high
centricity.
Compared with Fig. 2, Fig. 3 additionally shows a water supply 53 and water
return
54, as well as a water supply duct 43 and water return duct 44, said
embodiment
corresponding to Fig. 1
The water supply duct 43 and water return duct 44 are worked into nozzle 4 in
order
to improve the water cooling thereof. Therefore the cooling water enters an
annular
groove 45 which brings about a particularly good cooling of the thermally
maximum
stressed part of the nozzle 4, namely nozzle duct 46. As opposed to Fig. 2,
the
cooling water is directly supplied to this area. In the embodiment according
to Fig. 2
a tributary can form and part of the cooling water flows through it and is
then
unavailable for cooling nozzle duct 46. Through the design of nozzle 4 and the
nozzle protection cap 9 it is possible to fix the ratio of the proportions of
cooling
water which, via annular groove 45, cool nozzle duct 46 and conical outer
surface 47.
The improvement to the nozzle duct cooling whilst at the same time maintaining
cooling for the entire nozzle surface results from the worked in water supply
43 and
water return ducts 44 as well as a widening, i.e. an enlargement of the
conical areas
thereof, combined with an e.g. standard nozzle cap. It is ensured that there
is always a
closed, moving water film on the conical nozzle portion, whereas most of the
cooling
medium flows through the annular groove around the nozzle duct. The ratio of
the
surface areas can be in the range 3:1 to 20:1 (cooling duct:conical outer
surface).
The clear positioning of nozzle 4 relative to nozzle holder 5 through the
noses and
slots leads to an improvement in the cooling of nozzle 4. The noses and slots
also
facilitate the assembly, whilst at the same time bringing about high
centricity in the
final joining position.
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Fig. 4 shows the corresponding situation for an electrode 7 and electrode
holder 6.
Electrode 7 has a cylinder wall 71 with an outer surface 71a, a circular ring
surface 72
and a bearing surface 746. Electrode holder 6 has a cylinder wall 61 with an
inner
surface 61 a and a bearing surface 646. The internal diameter D61 a of
cylinder wall
61 is larger than the external diameter D71 a of cylinder wall 71. Five
identical slots
run round the outer surface 71a, but only two of these are visible and carry
reference
numerals 731 and 735.
Five identical, corresponding noses run round the inner surface, but only
three are
visible and carry reference numerals 632, 633 and 634.
In the direction of electrode 7 and upstream of noses 632 to 634, the
electrode holder
6 has an outwardly extending chamfer 62 facilitating the introduction of
electrode 7.
Internal diameter D62 corresponds to the diameter on the upper edge of chamfer
62
and gives a clearance Si (D62-D71a)/2. After passing chamfer 62 it tapers to
internal
diameter D52 in order to reduce the clearance almost to zero.
To improve the cooling of electrode 7, in the connection end there is a
subdivision
into a water supply duct 73 and water return duct 74 by means of a partition
75 and in
electrode holder 6 is provided a partition 65 for the subdivision into a water
supply
duct 63 and a water return duct 64 (cf. Fig. 5).
Fig. 6 shows slots 431 to 435 of nozzle 4 in engagement with the noses 531 to
535 of
nozzle holder 5 in the joining position. As the sum of two adjacent midpoint
angles
of angles a, 0, y, 6 and c under which slots 431 to 435 are arranged, is not
>_ 180 and
the five midpoint angles differ, only in this joining position can all the
noses be
brought into engagement with all the slots. In all other radial positions,
known as
joining positions, the circular ring surface 42 rests on at least three noses.
Fig. 7 shows the corresponding joining position and corresponding conditions
for the
joining position of electrode 7 and electrode holder 6.
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In the embodiments shown hereinbefore the depressions and projections or noses
and
slots are so positioned and dimensioned that it is no longer possible for
there to be any
twisting of the nozzle and nozzle holder or electrode and electrode holder
after
reaching the joining position
The features of the invention disclosed in the present description, drawings
and claims
can be essential both individually and in random combinations to the
implementation
of the different embodiments of the invention.
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REFERENCE NUMERALS LIST
1 Plasma torch head
2 Nozzle cap
3 Plasma gas guidance part
4 Nozzle
5 Nozzle holder
6 Electrode holder
7 Electrode
8 Nozzle protection cap holder
8a Insulating part
9 Nozzle protection cap
41 Cylinder wall
41a Outer surface
42 Circular ring surface
43 Water supply duct
44 Water return duct
45 Annular groove
46 Nozzle duct
47 Outer surface
51 Cylinder wall
51a Inner surface
52 Chamfer
53 Water supply
54 Water return
61 Cylinder wall
61a Inner surface
62 Chamfer
63 Water supply duct
64 Water return duct
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71 Cylinder wall
71a Outer surface
72 Circular ring surface
73 Water supply duct
74 Water return duct
431, 432,
433, 434,
435 Slots
531, 532,
533, 534,
535 Noses
546 Bearing surface
631, 632,
633, 634,
635 Noses
646 Bearing surface
65 Partition
731, 732,
733, 734,
735 Slots
746 Bearing surface
75 Partition
B Mean width of the noses and slots
D41a External diameter
D51a, D52,
D61 a, D62 Internal diameter
D71 a External diameter
PG Plasma gas
SG Secondary gas
T Mean depth/height of noses and slots
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WR1, WR2 Water returns
WV1, WV2 Water supplies
a, b, c, Radian measurements between the symmetry
d, axes of the noses/slots on the circumference
of diameter D in mm
a, (3, y, Midpoint angles between the symmetry
S, s axes of the noses/slots
