Title: Detecting element for a welding device
Abstract: The invention describes a welding apparatus (1), which has a current source (2) for supplying electrical power to at least one electrode at a welding torch (10) and a control system (4) co-operating with the current source (2), linked to an input device (22) for entering settings for different welding parameters, several sensing means being provided for detecting various actual values of a welding process. At least one measuring device or system for sensing mechanical motion, in particular a welding wire displacement and/or a welding torch displacement or similar, is provided, which detects a surface structure of an object.
Patent Number: 7,015,419 Issued on 03/21/2006 to Hackl, et al.
| Inventors:
|
Hackl; Heinrich (Ried/Traunkreis, AT);
Niedereder; Franz (Fischlham, AT);
Bernecker; Günther (Buchkirchen, AT)
|
| Assignee:
|
Fronius International GmbH (Pettenbach, AT)
|
| Appl. No.:
|
415632 |
| Filed:
|
October 11, 2001 |
| PCT Filed:
|
October 11, 2001
|
| PCT NO:
|
PCT/AT01/00326
|
| 371 Date:
|
May 1, 2003
|
| 102(e) Date:
|
May 1, 2003
|
| PCT PUB.NO.:
|
WO02/36296 |
| PCT PUB. Date:
|
May 10, 2002 |
Foreign Application Priority Data
| Nov 02, 2000[AT] | A 1851/2000 |
| Current U.S. Class: |
219/130.21; 219/137.71 |
| Current Intern'l Class: |
B23K 9/09.5 (20060101) |
| Field of Search: |
219/13771,130.21,130.01
356/285
|
References Cited [Referenced By]
U.S. Patent Documents
| 4334779 | Jun., 1982 | Domey et al.
| |
| Foreign Patent Documents |
| 199 14984 | Apr., 1999 | DE.
| |
| 0 157 148 | Feb., 1985 | EP.
| |
| 0369891 | Nov., 1989 | EP.
| |
| 0369891 | Nov., 1989 | EP.
| |
| 2583882 | Dec., 1986 | FR.
| |
| 58-187265 | Nov., 1983 | JP.
| |
| 06246451 | Sep., 1994 | JP.
| |
| 07182551 | Jul., 1995 | JP.
| |
| 07266043 | Oct., 1995 | JP.
| |
| 9-295141 | Nov., 1997 | JP.
| |
| 10206127 | Aug., 1998 | JP.
| |
Other References
Kramer, J. et al—"Pulse-Based Analog VLSI Volcity Sensors" 1997, (encl.).
|
Primary Examiner: Shaw; Clifford C.
Attorney, Agent or Firm: Collard & Roe, P.C.
Claims
What is claimed is:
1. A welding apparatus, having a current source for supplying electrical power
to at least one electrode at a welding torch and a control system co-operating
with the current source, linked to an input device for entering settings for different
welding parameters, several sensing means being provided for detecting various
actual values of a welding process, a measuring system disposed in the welding
torch upstream of a contact pipe between a drive system for the welding wire feed
and a linking element (
30) for a supply line (
12) or a hose pack,
wherein the measuring system consists of a light source, in particular a controlled
light source and an optical receiver, which acts on a sensor, and the measuring
system is furthermore programmed to detect the surface of the welding wire again
after a pre-set measuring cycle time has elapsed and an evaluation logic compares
the last detected pattern with the digitally stored pattern and the evaluation
logic is programmed to detect a shift in the pattern and calculate a distance of
travel or a changed position or the rate of the shift in the pattern.
2. Welding apparatus as claimed in claim 1, wherein the controlled light source
is disposed so as to produce a measurable contrast when the roughness or surface
structures of the object are illuminated.
3. Welding apparatus as claimed in claim 1, wherein the sensor, in particular
the evaluation logic, defines distinctive points or regions when evaluating the
first stored pattern and fixes coordinates corresponding to them, and, when it
detects the next pattern, recognizes a shift in the pattern, in particular of the
distinctive points or regions, and cumulates the altered positions of the coordinates
to ascertain a travel path of the welding wire.
4. Welding apparatus as claimed in claim 1, wherein the sensor, in particular
the evaluation logic, is programmed to determine an entire travel path of the welding
wire from the resultant cumulated changes in travel and to store the resultant
cumulated travel changes in a table with a time stamp.
5. Welding apparatus as claimed in claim 1, wherein the sensor, in particular
the evaluation logic, is programmed to detect the speed and conveyed quantity of
welding wire as an instantaneous and effective actual value.
6. Welding apparatus as claimed in claim 1, wherein the measuring system is connected
via lines, in particular via a field bus, to the control system of the welding
apparatus in order to transmit the detected travel path or position or the speed
of the welding wire.
7. Welding apparatus as claimed in claim 1, wherein the measuring system is programmed
to take a wire feed distance measurement and to calculate derived values based
on a time differential such as a speed or an acceleration or a jolt of the welding
wire (
13).
8. Welding apparatus as claimed in claim 1, wherein the measuring system is programmed
to take a measurement of the welding torch movement and to calculate derived values
based on a time differential such as a speed or an acceleration or a jolt of the
welding torch above the workpiece.
9. Welding apparatus as claimed in claim 1, wherein the control system of the
welding apparatus is programmed to detect and calculate the actual quantity of
welding wire displaced on the basis of the data transmitted by the measuring system.
10. Welding apparatus as claimed in claim 1, wherein the control system applies
a correction to at least one welding parameter during a welding process on the
basis of the data of the measuring system.
11. Welding apparatus as claimed in claim 1, wherein the control system is programmed
to detect any slipping in the driving gears by correlating data from the measuring
system with data of the drive system, in particular the feed motor voltage or the
feed motor transmitter values.
12. Welding apparatus as claimed in claim 1, wherein the measuring system is
programmed to monitor and detect any twisting or impact of the welding wire as
it is fed to the contact pipe and a forced contact made in the contact pipe.
13. Welding apparatus as claimed in claim 1, wherein the measuring system, in
particular the evaluation unit, is programmed to monitor contrast for the purpose
of detecting flaking or rust or a material of the welding wire.
14. Welding apparatus as claimed in claim 1, comprising a guide mechanism having
a guide bore for the welding wire.
15. Welding apparatus as claimed in claim 14, wherein the guide mechanism has
an orifice extending as far as the guide bore, by means of which the measuring
system is directed onto the welding wire.
16. Welding apparatus as claimed in claim 1, wherein the controlled light source
and the optical receiver are oriented in the direction of the welding wire as it
is fed past.
17. Welding apparatus as claimed in claim 1, wherein the measuring system is
programmed to contactlessly sense and evaluate the motion of the welding torch
towards the workpiece.
18. Welding apparatus as claimed in claim 1, wherein the measuring system is
disposed on the welding torch so that the light source and the optical receiver
are directed at the surface of the workpiece during a welding process.
19. Method of controlling or regulating a welding apparatus, in which various
actual values of a welding process are detected by various sensing means and a
welding wire displacement is sensed by a measuring system in the welding torch,
in particular upstream of a contact pipe or by means of a measuring system disposed
between a drive system for the welding wire feed and a linking element for a supply
line or a hose pack, and the detected actual values and the detected welding wire
displacement are used to control or regulate the welding process, comprising the
steps of detecting the welding wire displacement in such a way that a surface structure
of the welding wire is detected and stored by the measuring system and after a
predefined measuring cycle time has elapsed, again detecting the surface structure
of the welding wire, after which the detected surface structures are compared by
an evaluation logic of the measuring system and a corresponding shift in the surface
structures is recognized and detected, whereupon a travelled distance of the welding
wire or a changed position or a speed of the welding wire is calculated.
20. Method as claimed in claim 19, wherein the forward feed motion is detected
by the measuring system and an optical receiver acts on a sensor which detects
a roughness or the surface structure of the welding wire, in multiple dimensions
and stores it as a digital pattern, for which purpose the welding wire is illuminated
by a light source of the measuring system, in particular a controlled light source.
21. Method as claimed in claim 19, wherein the surface structure of the welding
wire is detected by the measuring system again once a predefined measuring cycle
time has elapsed, whereupon an evaluation logic in the sensor compares a first
detected pattern with a digitally stored pattern so as to detect a shift in the
pattern and calculates from this the distance travelled or a changed position or
a rate of shift in the pattern of the welding wire.
22. Method as claimed in claim 19, wherein the welding wire, is illuminated by
the controlled light source so that the roughness or surface structures of the
welding wire produces a measurable contrast.
23. Method as claimed in claim 19, wherein distinctive points or regions are
defined by the sensor during evaluation of the first stored pattern, for which
corresponding coordinates are fixed, and, when the next pattern is detected, the
measuring system recognizes that there has been a shift in the pattern, particularly
in the defined points or regions, and detects the changed positions of the coordinates
as a cumulated travel distance of the welding wire.
24. Method as claimed in claim 19, wherein the resultant cumulated change in
distance is used to determine the total distance travelled by the welding wire,
which is stored in a table with a time stamp.
25. Method as claimed in claim 19, wherein the speed and the quantity of welding
wire transported are detected as an instantaneous or effective actual value.
26. Method as claimed in claim 19, wherein the detected distance travelled or
position or speed of the monitored welding wire is forwarded by the measuring system
via lines, in particular via a field bus, to the control system of the welding apparatus.
27. Method as claimed in claim 19, wherein a distance measurement of a wire displacement
and its derived values based on time differential, such as a speed, an acceleration
or a jolt of the welding wire, are run or calculated by the measuring system.
28. Method as claimed in claim 19, wherein the actual amount of welding wire
fed along is detected or calculated by the control system of the welding apparatus
on the basis of the data transmitted by the measuring system.
29. Method as claimed in claim 19, wherein corrections are run or applied to
the welding parameters by the control system during a welding process on the basis
of the data from the measuring system.
30. Method as claimed in claim 19, wherein the control system detects any slipping
of the driving gears on the basis of the data of the measuring system correlated
with the data from the drive system, in particular the feed motor voltage or the
feed motor transmitter values.
31. Method as claimed in claim 19, wherein any twisting or impacts of the welding
wire as it is fed towards the contact pipe and the forced contact in the contact
pipe are monitored and detected by the measuring system.
32. Method as claimed in claim 19, wherein the contrast for detecting flaking
or rust of a material of the welding wire is monitored by the measuring system.
33. Method as claimed in claim 19, wherein the controlled light source and the
optical receiver are directed towards the welding wire as it is fed past.
Description
CROSS REFERENCE TO RELATED APPLICATIONS
Applicants claim priority under 35 U.S.C. §119 of Austrian Application
No. A 1851/2000 filed Nov. 2, 2000. Applicants also claim priority under 35 U.S.C.
§365 of PCT/AT01/00326 filed Oct. 11, 2001.
The invention relates to a welding apparatus of the type outlined in the generic
part of claim
1 and a method of controlling and/or regulating a welding
apparatus of the type outlined in the generic part of claim
23.
Patent specification U.S. Pat. No. 4,591,689 A discloses a system for a robot-controlled
welding system, in which the robot head is made up of a welding torch with a laser
and a visual unit for sensing the reflected laser beam. The robot head can be moved
into a whole range of positions by means of motors and the contactless system,
in other words the laser and visual unit, monitor the welding path by reference
to a groove or edge of the workpiece. A contactless measuring system of this type
incorporating a laser and a visual unit does not allow a path or movement on a
smooth surface to be monitored. To detect movements of this type, reference edges
or grooves or ridges must be provided so that the position can be detected by scanning
using the laser beam, followed by the subsequent guiding action.
A contactless method of measuring a displaced, structured object and a measuring
device are known from patent specification EP 0 157 148 A, in which the surface
of the structured object is scanned by means of a video camera and several brightness
profiles generated. By applying a similarity function between the stored brightness
profiles, the shift in position of the displaced object during the interval between
two video scans is calculated and the sum of calculated shifts in position with
effect from an initial instant is to calculate the length. The disadvantage of
this system is that the object must have a very distinctive structure for it to
be detected and evaluated by a video camera and it can not therefore be used as
a rule with non-structured objects, especially a metal object.
Patent specification U.S. Pat No. 5,514,851 A also discloses a system for
detecting movement of a welding torch, whereby a wheel is provided in addition
to the workpiece and the welding torch and the rotation of the wheel is measured
as a means of determining motion and speed.
Welding apparatus which enables mechanical motions or motion sequences, such
as the welding wire feed or the welding torch motion, to be sensed are already
known. Welding apparatus of this type has mechanical aids for this purpose, such
as tracker rollers, by means of which motion is sensed. These tracker rollers are
provided with sensors, by means of which the rotary motion of the tracker rollers
is sensed, thereby enabling appropriate parameters, such as speed, acceleration,
travel, etc., to be calculated.
The disadvantage of these systems is that the use of mechanical aids to sense
mechanical motion enables motion to be detected on an indirect basis only and any
interference factors, such as the slipping of rollers or gears can not be detected,
which leads to significant distortion of the measuring results.
The underlying objective of the invention is to propose a welding apparatus,
in which a mechanical motion an be detected or sensed without contact.
This objective is achieved by the invention due to the fact that at least one
device or a measuring system is provided for detecting a surface structure, as
a means of sensing a mechanical motion, in particular a displacement of the welding
wire or a displacement of the welding torch or similar. The advantage of this approach
is that by taking a direct measurement of the mechanical or manual displacement,
in particular of the welding wire and/or the welding torch, actual instantaneous
values can be obtained for subsequent processing, which significantly improves
the quality of the welding results. The quality of a weld can be enhanced still
further because the welding parameters are adapted to the actual motion, in other
words the actual instantaneous values, during the welding process. Another significant
advantage resides in the fact that incorrect operation of the welding apparatus,
such as the welding wire burning back to the contact pipe, can be avoided, because
the control system can be relied on to detect an interruption or reduction in the
wire feed and thus apply an appropriate control or correction, which will prevent
damage to the contact pipe and simultaneously avoid production having to be brought
to a halt.
Another advantage is that because the measuring system detects displacement
of the welding wire without contact, it can be retro-fitted on any welding apparatus
without any major expenditure, the use of this measuring system requiring nothing
more than a software modification at the control system and an equally straightforward
choice as to the positioning of the measuring system.
Other advantageous embodiments are described in claims
2 to
22.
The resultant advantages may be found in the description.
Irrespective of the above, the objective is also achieved by the invention
due to a method of controlling and/or regulating a welding apparatus based on the
features described in the characterising part of claim
23. The advantage
of this approach is that comparing the surface structures of an object on the basis
of predefined measuring cycles effectively prevents forward displacements from
being incorrectly detected because no mechanical means, such as drive rollers,
for example, are used.
Other advantageous features are described in the claims. The resultant advantages
may be found in the description.
The invention will be described in more detail with reference to examples embodiments.
Of the drawings:
FIG. 1 is a schematic diagram showing a welding machine or a welding apparatus;
FIG. 2 is a simplified, schematic diagram showing a welding wire feed device
for a welding wire, incorporating a measuring system;
FIG. 3 is a simplified, schematic diagram of one embodiment employing the measuring
system in a welding apparatus;
FIG. 4 is a simplified, schematic diagram showing an example of another application
employing the measuring system on a welding torch;
FIG. 5 is a simplified, schematic diagram showing a plan view of the welding
torch incorporating the measuring system, along the line of section V—V indicated
in FIG. 4.
Firstly, it should be pointed out that the same parts described in the different
embodiments are denoted by the same reference numbers and the same component names
and the disclosures made throughout the description can be transposed in terms
of meaning to same parts bearing the same reference numbers or same component names.
Furthermore, the positions chosen for the purposes of the description, such as
top, bottom, side, etc., relate to the drawing specifically being described and
can be transposed in terms of meaning to a new position when another position is
being described. Individual features or combinations of features from the different
embodiments illustrated and described may be construed as independent inventive
solutions or solutions proposed by the invention in their own right.
FIG. 1 illustrates a welding system and a welding apparatus
1 for a whole
range of welding processes, e.g. MIG-MAG welding and TIG welding or electrode welding
processes. Clearly, the solution proposed by the invention may be used with a current
source or a welding current source or a battery charging device.
The welding apparatus
1 has a current source
2 with a power component
3, a control system
4 and a switching element
5 co-operating
with the power component
3 and control system
4. The switching element
5 or the control system
4 is connected to a control valve
6
incorporated in a supply line
7 for a gas
8, in particular an inert
gas such as CO
2, helium or argon and such like, running between a gas
storage
9 and a welding torch
10.
Furthermore, a wire feed device
11 such as commonly used for
MIG-MAG welding may also be activated via the control system
4 in order
to feed a welding wire
13 from a supply reel
14 through a supply
line
12 into the region of the welding torch
10. Clearly, the wire
feed device
11 could also be integrated in the welding apparatus
1,
in particular in the basic housing, in a manner known from the prior art, rather
than used as an add-on device as illustrated in FIG. 1.
The current needed to strike an arc
15 between the welding wire
13
and a workpiece
16 is fed via a supply line
17 from the power component
3 of the welding current source
2 to the welding torch
10
and the welding wire
13, the workpiece
16 to be welded also being
connected to the welding apparatus
1, in particular to the welding current
source
2, via another supply line
18 so that a current circuit can
be established across the arc
15.
In order to cool the welding torch
10, the welding torch
10 can
be connected via a cooling circuit
19, with an integrated flow indicator
20, to a fluid container, in particular a water container
21, so
that the cooling circuit
19, in particular a fluid pump used to pump the
liquid contained in the water container
21, can be activated when the welding
torch
10 is switched on, thereby enabling the welding torch
10 and
the welding wire
13 to be cooled.
The welding apparatus
1 also has an input and/or output device
22,
by means of which a whole range of settings can be entered for welding parameters
and operating modes of the welding apparatus
1. The welding parameters entered
at the input and/or output device
22 are then forwarded to the control system
4, from where they are applied to the individual components of the welding
system and the welding apparatus
1.
In the embodiment illustrated as an example here, the welding torch
10
is also connected to the welding apparatus
1 and the welding system by means
of a hose pack
23. The individual lines from the welding apparatus
1
to the welding torch
10 are disposed in the hose pack
23. The hose
pack
23 is connected by means of a connector device
24, known from
the prior art, to the welding torch
10, whilst the individual lines in the
hose pack
23 are connected to the individual contacts of the welding apparatus
1 by means of connecting sockets and plug connectors. To relieve tension
on the hose pack
23, the hose pack
23 is connected via a tension-relieving
device
25 to a housing
26, in particular the basic housing of the
welding apparatus
1.
FIGS. 2 and 3 show a welding wire feed device
27, which may be used
both in the external wire feed device
11 illustrated in FIG. 1 and in the
welding apparatus
1, in particular in the housing
26 of the welding
apparatus
1.
The structure of the welding wire feed device
27 is of a type known from
the prior art and further details of the operating principle will therefore not
be described. The welding wire feed device
27 consists of a drive system
28, incorporating driving gears
29, and a linking element
30
for the welding wire
13. The driving gears
29 are driven by at least
one drive motor—not illustrated—enabling the welding wire
13
to be conveyed from the supply reel
14 via the supply line
12 or
via the hose pack
23 to the welding torch
10, the linking element
30 for the welding wire
13 being fed through the supply line
12
or into the hose pack
23.
The welding wire feed device
27 also has a new type of measuring system
31, illustrated in detail in FIG. 3, for monitoring the feed motion of the
welding wire, i.e. at least one device or the measuring system
31 for is
provided for sensing a surface structure, as a means of detecting a mechanical
motion, in particular a welding wire motion. The measuring system
31 is
preferably disposed between the drive system
28 and the linking element
30.
The measuring system
31 consists of a light source
32, in particular
a controlled light source
32, and an optical receiver
33 and the
optical receiver
33 acts on a sensor
34, prompting the sensor
34
to detect a roughness or a surface structure of an object, in particular the welding
wire
13, in multiple dimensions and stored this as a digital pattern, i.e.
the object to be measured, in particular the welding wire
13, is illuminated
by the controlled light source
32 so that the surface roughness or the structures
of the object surface show up as a measurable contrast. The surface roughness or
structures of the surface are captured by the optical receiver
33 and forwarded
to the sensor
34, which detects the captured multi-dimensional pattern and
stores it as a digital pattern.
After a pre-defined measuring cycle has elapsed, the surface of the object,
in particular the welding wire
13, is detected again and the last detected
pattern is compared with the digitally stored pattern by means of an evaluation
logic integrated in the sensor
34, from which the evaluation logic of the
sensor
34 will detect a shift in the pattern, enabling the distance travelled
or a change of position and/or the speed of the displacement to be calculated,
i.e. when the first stored pattern is evaluated, distinctive points or regions
are defined and coordinates corresponding to them are fixed so that when the next
pattern is detected, which naturally can also be stored, a shift in the pattern,
in particular the defined pints or regions, will be detected and the modified positions
of the coordinates cumulated as a distance measurement. The resultant cumulated
change in travel can be used as a means of determining the total distance travelled
and stored in a table with a time stamp, so that the speed of the welding wire
13 can be derived on a differential basis from the travel over time.
Once an evaluation or measuring process has been terminated, the last pattern
recorded by the sensor
34 is stored as a new digital pattern for another
comparison with another pattern, thereby enabling the displacement of the welding
wire
13 to be monitored on a constant and continuous basis. Consequently,
the measuring system
31 can be used to take a measurement of the wire forward
travel and derive other values on the basis of time difference, such as the speed
and/or acceleration and/or a jolt of the welding wire
13, in the welding
apparatus
1 or in the wire feed device
11, in particular in the welding
wire feed device
27.
This enables the speed and the transported quantity of welding wire
13
to be detected as an actual value on a more instantaneous basis, rather than sensing
and monitoring the displacement of the welding wire
13 on the basis of elements
acting on the welding wire
13, such as the driving gears
29 for example,
as is the case with the prior art until now. To date, this has been done on the
basis of the detected feed motor voltage or feed motor transmitter values of the
drive system
28, in particular the drive motor, or by means of a mechanical
transmitter in the form of a tracker roller. In this system, mechanical influences,
in particular slipping of the gear wheels
29, are not detected, which means
that erroneous data and values can arise. What this means is that in the event
of slipping of the driving gears
29 or slipping of the tracking rollers,
the actual value continues to be recorded but the welding wire is not displaced
in the same way, and the actual value detected is not correct.
This does not happen with the measuring system
31 because detection is
directly dependent on the displacement of the welding wire
13 and the measurement
result remains unaffected by mechanical influences of this nature. If the new measuring
system
31 is used in combination with the system known from the prior art,
in particular detection of the feed motor voltage and/or the feed motor transmitter
values, mechanical influences, in particular any slipping of the driving gears
29, can be detected by the control system
4, enabling an appropriate
correction to be applied by the control system
4 to prevent or eliminate
the mechanical influences, i.e. the control system
4 correlates the data
from the measuring system
31 with the data from the drive system
28,
in particular the feed motor voltage and/or the feed motor transmitter values and
detects when the driving gears are slipping, enabling appropriate controls and
corrections to be initiated.
To enable the measuring system
31 to forward the detected travel or position
and/or speed, the measuring system
31 is connected to the control system
4 of the welding apparatus
1 by lines, in particular via a bus system
or a field bus (not illustrated in FIG. 3). The control system
4 can then
control the drive system
28 accordingly or run a specific correction or
specific control of process parameters accordingly. For example, a current pulse
may be triggered after a defined amount of welding wire has been fed along. This
can be operated by releasing a droplet of a defined droplet size depending on the
distance travelled by the welding wire
13. Furthermore, the data supplied
by the measuring system
31 can be used to run other evaluations, for example
for quality control purposes, resulting in the input of a defined quantity of material
used and energy input, which can be documented for quality control purposes.
In order to be able to use such a measuring system
31, it is merely necessary
for the welding wire
13 to be moved past the measuring system
31,
as illustrated in detail in FIG. 3. To this end, a guide mechanism
35 with
a guide bore
36 for the welding wire
13 is provided, for example.
The guide mechanism
35 also has an orifice
37, extending as far as
the guide bore
36, above which the measuring system
31 is directed
onto the welding wire
13, i.e. the controlled light source
32 and
the optical receiver
33 are oriented in the direction of the welding wire
13 as it is moves past in order to illuminate the welding wire
13
so that the roughness or structures of the surface of the welding wire
13
can be picked up by the optical receiver
33, as schematically indicated,
and forwarded to the sensor
34. Using a configuration of this type means
that no foreign light source will be able to interfere with the measuring area
of the optical receiver
33, assuring a very high resolution. Whilst requiring
a very simple set-up, it can also be used at any position along the run of welding
wire to the welding torch
10.
Naturally, it would be possible to use any other configuration for the
measuring system
31. Accordingly, the measuring system
31 may be
used without any additional elements, such as guide mechanism
35, i.e. the
measuring system
31 merely has to be disposed at a specific distance from
the displaced object to be monitored, in particular the welding wire
13,
in order to run the measuring process described above.
As a result of the very compact structure and the fact that the measurement is
taken without the need for contact, the measuring system
31 can also be
integrated in the welding torch
10, as illustrated in FIG. 4, without making
it necessary to increase the dimensions of the welding torch
10. Any welding
torch
10 known from the prior art may therefore be used and it is not necessary
to describe the operating principle of the welding torch
10 in any further detail.
The standard welding torch
10 schematically illustrated in FIG. 4 has
a hand grip
39, a torch body
40 provided with an adapter
41
and a contact pipe
42, as well as a gas nozzle
43. The measuring
system
31 is preferably arranged in the vicinity of the welding process,
in other words in the region of the contact pipe
42. Consequently, the adapter
41 has an opening
44 through which the measuring system
31
can take a measurement of the roughness or surface structure of the welding wire
13.
Other monitoring functions and evaluations may be run by taking a continuous
measurement of the wire speed in the feed direction shortly before the contact
pipe
42. Whenever a feed error occurs in the welding wire
13, due
to the injector at the contact pipe
42, a bend in the welding wire
13
or a wire feed clutch mechanism slipping due to a blocked core for example, the
measurement taken in the welding torch
10 may be used to prevent the contact
pipe
42 from catching fire from the welding wire
13 as it emerges
from the contact pipe
42 because the welding wire displacement is detected
immediately before the contact pipe
42 and an appropriate control can be
initiated by the control system
4 during a pause. For example, the control
system
4 can halt the welding apparatus
1 and prevent further melting
of the welding wire
13 by varying the process parameter accordingly, for
example by reducing the output, in particular to zero.
Another possibility offered by the multi-dimensional sensing system, in particular
by two-dimensional sensing, is that, as well as taking a measurement in the direction
of the welding wire feed, a measurement can also be taken of the rotary and axial
paths and speeds of the welding wire
13 as it is drawn towards the contact
pipe
42 to monitor twisting or impacts of the welding wire
13 and
detect the forced contact in the contact pipe
42. To this end, it is merely
necessary to detect and set corresponding coordinates of the welding wire
13
on a one-off basis and store them, for example, in order to obtain an optimum delivery
so that the control system
4 need only run a simple comparison with the
data supplied by the measuring system
31 to operate this type of monitoring.
Naturally, the measuring system
31 may also be used for detecting
and determining other motion sequences. This being the case, the measuring system
31 could be used in conjunction with the drive system
28, for example,
in other words the driving gears
29, enabling the rotary motion of the driving
gears
29 to be ascertained and the rotational travel simultaneously detected.
The measuring system
31 may also be used for monitoring functions other
than sensing motion, in which case it would be possible to use the measuring system
31 to detect and monitor flaking and rust or a material of the welding wire
13 on the basis of contrast. For example, contrast could be employed for
the purpose of image sensing and used as a measurement value, i.e. by activating
the light source
32 depending on the control voltage or the control current,
so that an actual value van be ascertained or generated and then further processed.
A monitoring function of this type based on contrast may be used to detect the
state of the welding wire
13, for example, in particular to detect flaking
or rust or the material or composition of the welding wire
13. This being
the case, an upper and lower threshold value is set in order to trigger the light
source
32 so that a comparison can be run by actually activating the light
source to generate an image of a specific contrast, in order to ascertain whether
soiling is too extensive of if an alloy is incorrectly proportioned. To enable
different alloys to be detected, different upper and lower threshold values could
be stored for different welding wires
13 and the corresponding threshold
values fixed or selected depending on the setting entered from the input and/or
output device
22 (not illustrated in FIG. 4).
Another possible option would be to check for damage in the welding wire
13, such as scoring. A corresponding correction or control can then be applied.
Whenever so-called scoring is detected by the measuring system
31 or the
control system
4, for example, the contact pressure of the driving gears
29 on the welding wire
13 can then be minimised, thereby eliminating
damage of this nature. This will ensure an improved wire feed for the welding wire
13.
A significant advantage of the measuring system
31 primarily resides in
the fact that because the detection system operates without contact, it can be
very easily retrofitted on any system and used with robot-assisted applications,
since there is no need for major mechanical modifications to the existing system.
It would also be conceivable to devise applications for other motion sequences.
To this end, FIG. 5 illustrates a welding torch
10 configured for measuring
welding torch movements above the workpiece
16 and deriving values from
these on the basis of time, such as acceleration, speed, etc., i.e. the movement
of the welding torch
10 towards the workpiece
16 can be detected
and evaluated by the measuring system
31 without the need for contact.
In this case, the measuring system
31 is no longer directed onto the surface
of the welding wire
13 but is disposed on the welding torch
10 so
that the light source
32 and the optical receiver
33 are directed
onto the surface of the workpiece
16 during a welding process. This is schematically
indicated by broken lines in FIG. 4, whereas FIG. 5 gives a plan view along section
V—V indicated in FIG. 4.
The measuring system
31 may be of any structure and mounted by any fixing
means and, in the embodiment illustrated as an example here, the measuring system
31 is attached to the gas nozzle
43 by means of a housing
45,
schematically indicated. Naturally, it would also be possible for the measuring
system
31 to be mounted elsewhere on the welding torch
10, such as
on the torch body
40 or inside the gas nozzle
43, for example, in
which case it is merely necessary to ensure that the light source
32 and
the optical receiver
33 are oriented directly onto the surface of the workpiece
16.
If the measuring system
31 is used to sense or measure the surface of
the
workpiece
16, the movement of the entire welding torch
13 is sensed
by reference to the workpiece
16, in a manner similar to that described
with respect to the welding wire displacement. This can easily be set up for applications
involving the use of a manual welding torch without incurring any significant change
in the weight and/or flexibility of the welding torch
10.
For the purposes of manual welding or robot welding, the system provides a simple
means of detecting the welding rate and the actual value for travel so that the
control system
4 can adapt the welding parameters for any welding process
automatically, which will considerably enhance quality. In this connection, this
would enable the burning depth to be kept constant by applying an appropriate control.
It would also be possible to run an adjustment to maintain a constant or pre-set
welding rate, for example, for which purpose the control system
4 would
be used to generate corresponding optical and/or acoustic or electronic signals
for the user or another control system, which would in turn adapt the welding rates,
thereby enabling the user or robot to respond accordingly if there is any variance
from a pre-set welding rate.
Another option is to use a combination designed for internal and external
travel measurement sensing, in other words to run the operations described with
reference to FIGS. 2 to 5, resulting in various evaluation options. This being
the case, the weld seam length, the amount of material applied and the energy and
current input based on the machine parameters could be detected and evaluated by
logging the measurement results accordingly.
Using the measuring system
31 automatically provides the user or welder
with welding parameter default settings, i.e. when the welding torch
10
is switched off, welding will be detected as being at a welding rate of 0 cm/min
and the control system
4 will automatically pre-set a desired value of zero
for the welding power and simultaneously halt or reduce the wire feed if necessary,
for example. Consequently, the output of the welding apparatus
1 can be
pre-set and duly controlled depending on the welding rate.
For the sake of good order, it should be pointed out that in order to provide
a clearer understanding of the welding apparatus
1, it and its constituent
parts have been illustrated to a certain extent disproportionately and/or on an
enlarged scale or a reduced scale.
The independent solutions proposed by the invention in respect of the underlying
objectives may be taken from the description.
Above all, the individual embodiments illustrated in FIGS. 1;
2,
3;
4;
5 and their features may be construed as the subject matter of
independent solutions proposed by the invention in their own right. The related
objectives and solutions may be taken from the detailed descriptions of the drawings.
LIST OF REFERENCE NUMBERS
1 Welding apparatus
2 Welding current source
3 Power component
4 Control system
5 Switching element
6 Control valve
7 Supply line
8 Gas
9 Gas storage
10 Welding torch
11 Wire feed device
12 Supply line
13 Welding wire
14 Supply reel
15 Arc
16 Workpiece
17 Welding line
18 Welding line
19 Coolant circuit
20 Flow indicator
21 Water container
22 Input and/or output device
23 Hose pack
24 Connecting device
25 Tension-relieving device
26 Housing
27 Welding wire feed device
28 Drive system
29 Driving gear
30 Linking element
31 Measuring system
32 Light source
33 Receiver
34 Sensor
35 Guide mechanism
36 Guide bore
37 Office
38
39 Hand grip
40 Torch body
41 Adapter
42 Contact pipe
43 Gas nozzle
44 Opening
45 Housing
*
