U.S. patent application number 10/316971 was filed with the patent office on 2004-06-17 for method and system for weld process monitoring.
Invention is credited to Nastasi, John D. JR..
Application Number | 20040112874 10/316971 |
Document ID | / |
Family ID | 32392948 |
Filed Date | 2004-06-17 |
United States Patent
Application |
20040112874 |
Kind Code |
A1 |
Nastasi, John D. JR. |
June 17, 2004 |
METHOD AND SYSTEM FOR WELD PROCESS MONITORING
Abstract
A weld tip testing element is presented. The weld tip testing
element includes a first alignment member and a first lever element
coupled to the alignment member. The first lever element is further
coupled to a first pivot and the first alignment member is operable
to determine a first alignment associated with a weld tip. If the
weld tip is out of alignment the weld tip contacts the first
alignment member.
Inventors: |
Nastasi, John D. JR.;
(Warren, OH) |
Correspondence
Address: |
Baker Botts L.L.P.
2001 Ross Avenue, Suite 600
Dallas
TX
75201-2980
US
|
Family ID: |
32392948 |
Appl. No.: |
10/316971 |
Filed: |
December 11, 2002 |
Current U.S.
Class: |
219/109 |
Current CPC
Class: |
B23K 11/252 20130101;
B23K 11/3063 20130101 |
Class at
Publication: |
219/109 |
International
Class: |
B23K 011/24 |
Claims
What is claimed is:
1. A weld tip testing element comprising: a first alignment member;
a first lever element coupled to the alignment member; the first
lever element being further coupled to a first pivot; and wherein
the first alignment member is operable to determine a first
alignment associated with a weld tip, wherein if the weld tip is
out of alignment the weld tip contacts the first alignment
member.
2. The weld tip testing element according to claim 1, wherein the
first alignment member further comprises a aperture disposed
therethrough, wherein the aperture is operable to removeably
receive the weld tip.
3. The weld tip testing element according to claim 2, wherein a
size of the aperture is based on an alignment tolerance associated
with the weld tip and wherein the first alignment member and the
first lever element are enclosed in a housing.
4. The weld tip testing element according to claim 1 and further
comprising: a mounting coupled to the first pivot and operable to
support the first pivot, the first lever element and the first
alignment member; and a first sensor coupled to the mounting and
operable to detect movement of the first lever element.
5. The weld tip testing element according to claim 4, wherein the
first sensor is further operable to detect misalignment of the weld
tip based on contact between the first sensor and the first lever
element.
6. The weld tip testing element according to claim 5 and further
comprising: a second alignment member coupled to the mounting, the
second alignment member operable to detect a second alignment
associated with the weld tip; a second lever element coupled to the
second alignment member and coupled to the mounting; wherein the
first and second alignment members form an aperture operable to
removably receive the weld tip; and wherein if the weld tip is out
of alignment, at least one of the first and second lever elements
moves in response to contact between the weld tip and at least one
of the first and second alignment members.
7. The weld tip testing element according to claim 1 and further
comprising: computer software encoded on storage and operable to:
receive first alignment information from the first sensor; analyze
the first alignment information with respect to at least one
expected alignment value; generate an alarm based on the analysis;
and generate a fault based on the analysis.
8. The weld tip testing element according to claim 7, wherein the
computer software is further operable to: generate the alarm when
the first alignment is outside a range of expected alignments, the
expected alignments indicating proper values for the first
alignment; and generating the fault when the alarm is within a
range of fault alignments, the fault alignments indicating values
associated serious mis-alignment of the weld tip.
9. The weld tip testing element according to claim 1, wherein the
weld tip comprises a pair of weld tips and further comprising: a
pressure sensor operable to determine a squeeze force associated
with the weld tips, the pressure sensor coupled to the mounting;
and a heat sensor operable to determine a temperature associated
with the weld tip, the heat sensor coupled to the mounting.
10. The weld tip testing element according to claim 1, wherein the
first alignment member comprises a generally flat bar with at least
one generally rounded end and having an aperture disposed
therethrough.
11. The weld tip testing element according to claim 1, wherein the
first alignment member operates to depress in response to contact
with the weld tip and wherein the first lever element causes
generation of a piezo-electric charge in response to contact with
the first sensor.
12. The weld tip testing element according to claim 1, wherein the
alignment member comprises a generally circular element.
13. A weld process monitor comprising: a pressure sensor operable
to determine a squeeze force associated with a weld tip, the
pressure sensor coupled to a mounting; a heat sensor operable to
determine a temperature associated with the weld tip, the heat
sensor coupled to the mounting; a pivot coupled to the mounting; an
alignment member having an aperture disposed therein and coupled to
a lever element, the lever element being further coupled to the
pivot, wherein the aperture is operable to removably receive the
weld tip; an alignment sensor operable to detect movement of the
lever element and determine an alignment associated with the weld
tip; and computer software encoded on storage and operable to:
analyze at least one of the squeeze force, the temperature and the
alignment with respect to at least one expected value; generate an
alarm based on the analysis; and generate a fault based on the
analysis.
14. The weld process monitor according to claim 13, wherein the
alignment member comprises a generally flat bar with a generally
rounded end and having the aperture disposed therethrough.
15. The weld process monitor according to claim 13, wherein the
software is further operable to: compare one of the squeeze force,
the temperature or the alignment to one of a respective range of
expected squeeze forces, a range of expected temperatures or a
range of expected alignments; generate the alarm when one of the
squeeze force, the temperature or the alignment exceeds one of the
range of respective expected squeeze forces, expected temperatures
or expected alignments, the alarm including one of the squeeze
force, the temperature or the alignment and one of the range of
expected squeeze forces, expected temperatures or expected
alignments; and communicate the alarm to an appropriate
recipient.
16. The weld process monitor according to claim 13, wherein the
software is further operable to: compare one of the squeeze force,
the temperature or the alignment to one of a range of fault squeeze
forces, a range of fault temperatures or a range of fault
alignments; generate the fault when one of the squeeze force, the
temperature or the alignment is respectively within one the range
of fault squeeze forces, the range of fault temperatures or the
range of fault alignments, the fault including at least one of the
squeeze force, the temperature and the alignment and at least one
of the range of fault squeeze forces, the range of fault
temperatures and the range of fault alignments; and communicate the
fault to an appropriate recipient.
17. The weld process monitor according to claim 13, wherein the
alignment sensor is operable to determine the alignment of the weld
tip in response to the weld tip touching the alignment member
moving the lever element about the pivot to contact the alignment
sensor.
18. The weld process monitor according to claim 17, wherein the
alignment member further operates to depress in response to contact
with the weld tip and wherein the alignment sensor causes
generation of a piezo-electric charge in response to contact
between the lever element and the alignment sensor.
19. The weld process monitor according to claim 13, wherein the
alignment member comprises a generally circular element and a size
of the aperture is based on an alignment tolerance associated with
the weld tip.
20. The weld process monitor according to claim 13, wherein the
alignment member is generally circular; wherein the lever portion
comprises a rod; wherein the aperture is generally circular;
wherein the pressure sensor comprises one of a strain gauge or a
mechanical sensor; and wherein the heat sensor comprises one of an
infrared sensor or a thermocouple.
Description
TECHNICAL FIELD
[0001] This invention relates in general to welding, and, more
specifically to a method and system for weld process
monitoring.
BACKGROUND
[0002] As computers have grown increasingly important in today's
society, various industries have increasingly adopted computer
controlled systems for more efficient and effective control and
monitoring of equipment. Industries using automatic welding have
increasingly used computer controlled equipment.
[0003] Industries involved with automatic welding have turned to
computer controlled machinery to increase the efficiency of
assembly lines. One common operation on an assembly line is the
welding together of components. The welding operation is often
performed automatically by a computer-controlled welding device.
Often, a determination of proper operation of the welding device is
performed manually by inspecting welds after they are performed.
For example, a pry test may be used to determine a bad weld that
has not properly joined two elements. However, manual inspection
can be undesirable as many bad welds can be created before a
problem is detected.
SUMMARY
[0004] The present invention provides a system for weld process
monitoring. In one embodiment of the present invention, a weld tip
testing element is described. A weld tip testing element is
presented. The weld tip testing element includes a first alignment
member and a first lever element coupled to the alignment member.
The first lever element is further coupled to a first pivot and the
first alignment member is operable to determine a first alignment
associated with a weld tip. If the weld tip is out of alignment the
weld tip contacts the first alignment member.
[0005] The present invention provides numerous technical
advantages. Various embodiments of the present invention may
provide all, some or none of these technical advantages. One such
technical advantage is the capability to detect possible welding
problems before many bad welds are made. By checking various
elements of the performance of the welding equipment, problems and
developing problems may be more quickly detected. Early detection
of problems decreases the number of bad welds and increases the
productivity of, for example, an assembly line. Another technical
advantage is the ability to monitor weld systems with small throat
distances.
BRIEF DESCRIPTION OF THE DRAWINGS
[0006] The present invention is best understood from the detailed
description which follows, taken in conjunction with the
accompanying drawings, in which:
[0007] FIG. 1 is a block diagram illustrating a weld process
monitoring system according to one embodiment of the present
invention;
[0008] FIG. 2 is a side view illustrating details of a testing
element associated with the monitoring system of FIG. 1 according
to one embodiment of the present invention;
[0009] FIG. 3 is a top view of the testing element according to one
embodiment of the present invention;
[0010] FIG. 3A is a top view illustrating an alignment element
according to one embodiment of the present invention;
[0011] FIG. 4 is a diagram illustrating further details of a tip
dresser associated with the monitoring station of FIG. 1 according
to one embodiment of the present invention; and
[0012] FIG. 5 is a flow chart illustrating an exemplary method of
operation of the monitoring system of FIG. 1 according to one
embodiment of the present invention.
DETAILED DESCRIPTION
[0013] FIG. 1 is a block diagram illustrating a weld process
monitoring system 10. System 10 comprises an assembly line 12, a
welding station 14, a weld arm 16, a control system 18 and a
monitoring station 20.
[0014] Assembly line 12 comprises a suitable assembly line for
placing physical items in a location accessible by welding station
14. More specifically, assembly line 12 may move physical products
along a predetermined path such that welding station 14 is given
suitable time to perform one or more welds on the products.
[0015] Welding station 14 comprises a station for performing
automated, manual and/or partially manually controlled welding on
products on assembly line 12. More specifically, welding station 14
may provide mechanical and/or logical control of welding arm 16 for
welding products on assembly line 12.
[0016] Welding arm 16 comprises an articulated or non-articulated
arm operable to move to weld products on assembly line 12. Welding
arm 16 also comprises one or more weld tips 22.
[0017] Weld tips 22 comprise tips operable to create a weld. In one
embodiment, weld tips 22 comprise copper tips used to perform
resistive welding and may be water cooled or air cooled. The
invention is not limited to any specific number of weld tips 22,
any particular material for fabrication weld tips 22, or any kind
of cooling mechanism.
[0018] In one embodiment, weld tips 22 face each other and are
brought together on opposite sides of the location of the weld.
When weld tips 22 are a suitable distance from each other and the
weld location, the weld is performed in a suitable way. Welding arm
16 may pivot, rotate or otherwise move in a suitable manner to
appropriately position weld tips 22. The distance from weld tips 22
to welding arm 16 is known as a throat distance. More specifically,
the throat distance comprises the distance from the weld tips to
the point where the arm holding the weld tips is coupled to another
object, such as equipment for moving the weld tips.
[0019] Control system 18 comprises a processor 24 and/or storage
26. Processor 24 comprises a suitable general purpose or
specialized data processing device, such as an application specific
integrated circuit (ASIC), a field programmable gate array (FPGA),
a general purpose central processing unit (CPU) or other suitable
hardware operable to execute computer software stored in storage
26.
[0020] Storage 26 comprises suitable transient and/or persistent
computer-readable storage, such as a computer-readable medium,
either alone or in suitable combination. For example, storage 26
may comprise one or more of magnetic storage, optical storage,
electronic storage, such as random access memory (RAM) and dynamic
random access memory (DRAM) and other suitable physical, optical or
electronic storage in suitable combination. Storage 26 is operable
to store computer instructions executable by processor 24.
Alternatively, the functions performed by control system 18 may be
performed by a combination of hardware and software or may exist
entirely in hardware.
[0021] Control system 18 is operable to assist welding station 14
in the operation and control of weld arm 16 and weld tips 22.
Control system 18 is further operable to receive information from
monitoring station 20 and welding station 14 for storage and
analysis. For example, control system 18 may receive errors or
other data generated at welding station 14 or monitoring station 20
for recording in a log on storage 26. Multiple control systems 18
may be used for different components without departing from the
scope of the invention. In addition, data associated with
monitoring station 20 may be sent to one or more remote computers
or other systems.
[0022] Monitoring station 20 comprises a testing element 30 and a
tip dresser 32. Monitoring station 20 is operable to perform
various testing and repair actions on weld tips 22.
[0023] Testing element 30 is operable to perform one or more tests
on weld tips 22. For example, testing element 30 may determine weld
tip cooling status, weld tip alignment, available squeeze force of
weld tips 22, a pneumatic component status associated with arm 16,
and force settings associated with welding station 14. Some of
these tests may be omitted or other tests performed without
departing from the scope of the invention. Testing element 30 is
described in greater detail in association with FIGS. 2 and 3.
[0024] Tip dresser 32 is operable to repair weld tips 22. More
specifically, as weld tips 22 are used to weld products on assembly
line 12, weld tips 22 may become dull. Tip dresser 32 operates to
sharpen weld tips 22. Tip dresser 32 is discussed in greater detail
in association with FIG. 4.
[0025] In operation, products move along assembly line 12 to
welding station 14. Welding station 14 then instructs weld arm 16
to create one or more welds on the product on assembly line 12. For
example, arm 16 may be articulated and move weld tips 22 to the
location where welds are needed. Weld tips 22 then generate welds
as appropriate. In one embodiment, weld tips 22 squeeze around the
desired location of the weld and then use resistive welding to
generate a weld. More specifically, arm 16 may move weld tips 22
closer together so as to hold the portions of the product to be
welded in a stationary and touching position while the weld is
completed. After a predetermined number of jobs, welding station 14
moves weld tips 22 to monitoring station 20 or moves monitoring
station 20 to weld tips 22. At monitoring station 20, various tests
are performed on weld tips 22 by testing element 30 and tip dresser
32. Welding station 14 then returns weld arm 16 and weld tips 22 to
welding products on assembly line 12.
[0026] Monitoring station 20 may determine one or more items of
information from testing element 30. For example, monitoring
station 20 may determine weld tip cooling status, weld tip
alignment status, weld tip squeeze force status, pneumatic
component status, welding force setting status, tip dressing force
status, weld tip attitude with respect to tip dresser 32, tip
dresser force capability status, air-binary-regulator status with
respect to regulation of weld tip force, tip dresser dwell time,
tip dresser blade status, whether the weld arms are bent and
whether a monitoring operation has been missed.
[0027] FIG. 2 is a side view illustrating details of an example of
a testing element 30 constructed in accordance with the invention.
FIG. 3 is a top view of testing element 30. FIGS. 2 and 3 are
discussed together for increased clarity. Testing element 30
comprises a mounting 50, one or more alignment elements 52, one or
more sensors 53, a pressure sensor 54, a temperature sensor 56, an
aperture 58, a lever portion 60 and a pivot 62.
[0028] Mounting 50 provides an essentially stable attachment to
monitoring station 20 such that testing element 30 is relatively
securely mounted to monitoring station 20. For example, mounting
element 50 may comprise a steel arm. Mounting element 50 could be
any suitable shape and could be made of many different materials. A
portion of mounting 50 may comprise a housing which encloses
alignment elements 52, sensors 53, pressure sensor 54, temperature
sensor 56, aperture 58, lever portion 60 and pivot 62 such that
these elements are protected from debris and weld slag. By
protecting alignment elements 52, sensors 53, pressure sensor 54,
temperature sensor 56, aperture 58, lever portion 60 and pivot 62
from debris and weld slag, increased reliability may be achieved.
For example, weld slag from weld tips 32 may prevent alignment
elements 52 from operating and the housing may allow testing
element 30 to provide more reliable operation. The housing may be
made of any suitable material, such as metal or plastic, and shaped
such that weld tips 32 may be inserted and removed from aperture
58.
[0029] Alignment elements 52 comprise elements operable to detect a
misalignment of weld tips 22. In one embodiment, alignment elements
52 comprise members shaped like portions of a washer or an entire
washer operable to move in response to contact with weld tips 22.
More specifically, alignment element 52 pivots around pivot 62 and
moves lever portion 60 into contact with sensor 53. Further,
alignment element 52 may use one or more springs to return and/or
retain alignment element 52 in a particular position. For example,
the spring may be used to return alignment element 52 to an initial
position after contact with a misaligned weld tip 32. For another
example, if alignment element 52 is mounted
[0030] The shape of alignment elements 52 is relatively
unimportant, as is the number of alignment elements 52 SO long as
alignment elements 52 are operable to detect misalignment of weld
tips 22. In one embodiment, a single alignment element 52 is
located on each of opposing sides of testing element 30. However,
multiple alignment elements 52 could be included such that the
direction of misalignment could be sensed. For example, four
sensors could be placed to generally form a washer-like shape to
locate misalignment in one of four quadrants. Alternatively,
alignment element 52 may comprise a laser, an infrared sensor or
other suitable mechanical, electrical or optical alignment
detection equipment. Movement of alignment elements 52 is
detectable by monitoring station 20. The particular alignment
element 52 which is moved may also be available to monitoring
station 20.
[0031] In one embodiment, alignment element 52 may comprise a
generally circular element coupled to an end of lever portion 60.
Lever portion 60 may comprise a rod, bar or other object operable
to support alignment element 52 and pivot about pivot 62. Lever
portion 60 may be formed as part of alignment element 52 or may be
separately coupled to alignment element 52. Lever portion 60 may
further be of a size different from alignment element 52. For
example, as shown in FIG. 3, lever portion 60 may be smaller than
alignment element 52.
[0032] In one embodiment, weld arm 16 and weld tips 22 may be used
for small welds and be limited in movement. More specifically, the
maximum distance between weld tips 22 may be approximately 1.25
inches, while weld tips 22 and arm 16 for larger welds may be
capable of opening approximately 6 inches. In addition, weld tips
22 may have short throat distances when precision welding systems
are used. Alignment elements 52 may be selected based on the
distance between weld tips and the throat distance. For example,
particular alignment elements 52 may be physically too large to
implement for a particular set of weld tips 22.
[0033] Aperture 58 is disposed within alignment element 52 and
allows insertion of weld tips 22 through alignment element 52. If
weld tips 22 are not aligned with aperture 58, then alignment
element 52 will be activated. The size of aperture 58 may be varied
in order to set particular tolerances for the alignment of weld
tips 22. For example, a three-quarter inch tip may be used with a
seven-eighths inch aperture 58 so as to allow minimal tolerance for
misalignment of weld tips 22.
[0034] Sensor 53 comprises a detection element operable to detect
movement of lever portion 60. In one embodiment, sensor 53 may
detect contact between lever portion 60 and sensor 53 in response
to force applied to alignment element 52, such as when weld tip 22
comes into contact with alignment element 52. In one embodiment,
contact between sensor 53 and lever portion 60 causes generation of
a piezo-electric charge which is receivable by monitoring station
20 for analysis by control system 18. In another embodiment,
movement of alignment elements 52 by sensors 53 may be detected by
a laser or other optical system, for example, where the movement of
alignment element 52 and/or lever portion 60 breaks one or more
laser beams. In general, one or more sensors 53 may be coupled to
mounting 50 for detecting movement of alignment element 52. For
example, sensor 53 may comprise a laser, a piezo-electric current
generator responsive to spring 53, a mechanical sensor, an optical
sensor, an electronic sensor, a magnetic sensor or other suitable
sensing device, either alone or in suitable commination.
[0035] Force sensor 54 comprises a sensor element operable to
measure the force exerted by weld tips 22. For example, force
sensor 54 may comprise a strain gauge, a load cell, or other
mechanical force sensors.
[0036] Temperature sensor 56 comprises a sensor operable to detect
the temperature of welding tip 22. Temperature sensors 56 may be
operable to individually determine the temperature of the one of
weld tips 22 to which the temperature sensor 56 is adjacent. For
example, temperature sensors 56 may detect the heat radiated by
weld tips 22 as weld tips 22 are inserted into testing element 30.
Infrared sensor 56 may comprise an infrared heat sensor, a
thermocouple or other suitable temperature measurement equipment.
As noted, one temperature sensor 56 may separately determine the
temperature of an upper weld tip while a second temperature sensor
56 determines the temperature of a lower weld tip.
[0037] Lever portion 60 comprises a portion of alignment element 52
operable to indicate contact between alignment element 52 and weld
tips 22. Alternatively, lever portion 60 may be coupled to a
distinct alignment element 52. More specifically, lever portion 60
may move in response to contact between alignment element 52 and
weld tips 22 to activate sensor 53 and indicate misalignment of
weld tips 22. Lever portion 60 may be of suitable shape, size and
weight as appropriate with respect to weld tips 22. For example,
lever portion 60 may be generally as wide as the diameter of
alignment element 52, or may be smaller or larger. For another
example, lever portion 60 may outweigh alignment element 52 so that
lever portion 60 moves only when alignment element 52 is moved by
misaligned weld tips 22.
[0038] Pivot 62 comprises a suitable pivot point operable to
support alignment element 52 and lever portion 60, and allow
movement of alignment element 52 and lever portion 60. For example,
pivot 62 may comprise a hinge, a pin, a rod or other suitable pivot
element.
[0039] In operation, weld tips 22 are inserted into testing element
30 through aperture 58. If weld tips 22 are misaligned from their
expected position, then weld tips 22 will impact one or more of
alignment elements 52. If alignment elements 52 move in response to
weld tips 22, then monitoring station 20 will sense a misalignment
of weld tips 22. Alternatively, when alignment element 52 comprises
optical devices, such as lasers, mis-alignment may be detected by
intersection of weld tips 22 with a laser beam. More specifically,
lever portion 60 moves around pivot 62 in response to movement of
alignment elements 52 and activates sensor 53 to indicate
misalignment of weld tips 22.
[0040] In one embodiment, by detecting which alignment elements 52
are moved, monitoring station 20 may be given more detailed
information with respect to the nature and extent of the
misalignment of weld tips 22 where multiple sensors are used on
each side of testing element 30.
[0041] Temperature sensors 56 determine the current temperature of
weld tips 22 and the associated data is captured by monitoring
station 20. Force sensor 54 determines the amount of pressure
provided by weld tips 22 and the associated data is also captured
by monitoring station 20. More specifically, weld tips 22 may be
inserted into aperture 58 with the same amount of speed and
pressure used when weld tips 22 are welding products. After
relevant measurements have been made, weld tips 22 withdrawn from
testing element 30 can be moved to tip dresser 32 or can be
returned to performing welding.
[0042] FIG. 3A is a top view of one embodiment of alignment member
52 and lever portion 60. In this embodiment alignment element 52
may comprise a generally flat bar with a hole, or other suitable
aperture, at the end. The bar may be made of metal, plastic or
other suitable material. Lever portion 60 of the bar is generally
rectangular and alignment member 52 is generally rounded.
[0043] FIG. 4 is a diagram illustrating further details of tip
dresser 32. Tip dresser 32 comprises a tip dresser element 100, a
load sensor 101 and a vibration sensor 102. Tip dresser element 100
comprises an element operable to receive weld tip 22 and sharpen
weld tip 22. More specifically, tip 22 is inserted in tip dresser
element 100 to be sharpened. Tip dresser element 100 may use
spinning blades driven by a motor to sharpen weld tips 22.
Typically, the act of sharpening a weld tip 22 is referred to as
"tip dressing". dresser element 100 may be coupled to monitoring
station 20.
[0044] Motor load current sensor 101 is coupled to tip dresser
element 100 and is operable to detect the electrical current draw
of the motor driving the blades of tip dresser element 100. Motor
load current sensor 101 communicates the electrical current draw of
the tip dresser motor to monitoring station 20.
[0045] Peak vibration accelerometer 102 detects the peak vibration
of tip dresser element 100. By detecting the vibration of tip
dresser element 100, peak vibration accelerometer 102 is operable
to detect an unbalanced or malfunctioning tip dresser motor.
[0046] In operation, weld tips 22 are inserted into tip dresser
element 100 for sharpening. Tip dresser element 100 then rotates
one or more blades at an appropriate speed in order to sharpen weld
tips 22. More specifically, tip dresser element 100 attempts to
form a pointed tip on weld tips 22. Current sensor 101 measures the
amount of electrical current drawn by a motor driving the blades
and communicates the amount of electrical current drawn by the
motor to control system 18 for analysis. The amount of electrical
current drawn by the motor may indicate a failing motor, such as by
drawing more electrical current than usual, dulled blades or other
problems. Accelerometer 102 detects the amount of vibration
resulting from operation of tip dresser element 100. The detected
vibration levels are communicated to control system 18 for
analysis. For example, increasing vibration may indicate a broken
blade which is unbalancing tip dresser element 100.
[0047] FIG. 5 is a flow chart illustrating an exemplary method of
operation of system 10, unless an order for the various steps is
obviously required, the steps could occur in any order. The method
begins at step 200, where control system 18 determines whether the
check interval for weld arm 16 and weld tips 22 has been reached.
Alternatively, control system 18 may monitor tip dresser 32. More
specifically, control system 18 may monitor tip dresser 32 for the
start of a motor driving tip dresser 32. Control system 18 may use
the start of the motor for tip dresser 32 to indicate that weld
tips 22 are to be checked by testing element 30. For example,
timing or other logic associated with tip dresser 32 may determine
that weld tips 22 are to dressed and control system 18 may use this
logic to activate testing element 30 and test weld tips 22. By
monitoring tip dresser 32, testing element 30 may operate more
independently of other elements of system 10. For example, testing
element 30 may be added to an existing system such that testing
element 30 monitors tip dresser 32 which may decrease the cost of
adding testing element 30 to an existing system.
[0048] In one embodiment, the check interval is reached when
welding station 14 has performed a certain number of jobs, where a
job comprises a certain number of welds. For example, after five
jobs involving ten welds each, control system 18 may determine that
the check interval has been reached and have welding station 14
move control arm 16 and weld tips 22 to monitoring station 20 for
testing. Alternatively, monitoring station 20 may move to weld tips
22 or both weld tips 22 and monitoring station 20 may move.
[0049] Next, at step 202, testing element 30 determines the
temperature of weld tips 22. More specifically, using temperature
sensors 56, the temperature of weld tips 22 may be determined. Once
the temperature of weld tips 22 is determined, the amount of
cooling being provided at the weld tip may be determined by
comparing the actual temperature of weld tips 22 to an expected
temperature or range of temperatures for weld tips 22. Thus,
malfunctions in the weld tip cooling system or defects in the weld
tips 22 may be detected. More specifically, weld tips 22 may be
cooled using a water cooling system where water is circulated
through arm 16 to weld tips 22 to draw away heat generated during
the welding process. Improper cooling of weld tips 22 may
contribute to decrease the life span of weld tips 22 and increase
the chance of improper welding.
[0050] At step 204, the alignment of weld tips 22 is determined by
monitoring station 20. More specifically, as weld tips 22 are
inserted in testing element 30, alignment elements 52 may be moved.
If the alignment elements 52 are moved by weld tips 22, then weld
tips 22 and/or arm 16 are not correctly aligned. Control system 18
and monitoring station 20 can then use this information to realign
arm 16 and/or weld tips 22 and/or to inform repair personnel of the
need to realign arm 16 and weld tips 22.
[0051] Proceeding to step 206, the squeeze force applied to weld
tips 22 is determined. More specifically, force sensor 54 measures
and records the amount of pressure exerted by weld tips 22. As weld
tips 22 are used to weld products on assembly line 12, their
capability to squeeze with sufficient force may decrease due to
wear or other problems. Monitoring station 20 may be used to ensure
that the proper squeeze force is applied to properly weld products.
The measured squeeze force at sensor 54 may be communicated to
monitoring station 20 for analysis at control system 18 and/or sent
to remote computer systems.
[0052] Then, at step 210, weld tips 22 are moved from testing
element 30 to tip dresser 32 (or tip dresser 32 is moved or weld
tips 22 and tip dresser 32 are both moved). At tip dresser 32 the
force setting of tip dressing element 100 is determined. More
specifically, the amount of force used to spin the cutting blades
of tip dresser element 100 is determined using the current
measurement described above.
[0053] At step 214, accelerometer 102 is used to detect excess
vibration, which could indicate a bent weld gun or bad
alignment.
[0054] Next, at step 218, the interval since the last check
performed by monitoring station 20 and arm 16 and weld tips 22 is
determined. More specifically, control system 18 analyzes
information from monitoring station 20, such as the time of the
present check of arm 16 and weld tips 22, and determines if an
unusual and/or unexpected amount of time has passed since the last
check operation.
[0055] Proceeding to step 220, the amount of time taken by the tip
dressing operation by tip dresser element 100 is determined. Then,
at step 222, damaged cutter blades in tip dresser element 100 are
detected based upon this time interval and/or a vibration analysis
using accelerometer 102.
[0056] Then, at step 224, cutter blade sharpness is estimated. More
specifically, cutter blade sharpness is estimated by analyzing the
amount of time needed to sharpen the weld tip 22. Dull cutter
blades may not sharpen tip 22 appropriately and/or may take an
unexpected amount of time.
[0057] Then, at step 228, control system 18 analyzes the results of
steps 200 through 226. More specifically, a predetermined
acceptable range may be associated with each measured item, such as
temperature, alignment and squeeze force. The measured value is
then compared to the expected value. In addition, control system 18
may have fault ranges for the various measured elements, such as
temperature, alignment and squeeze force, may be provided to system
18. Control system 18 may then compare the measured values to the
fault range of values. The fault range indicates operating values
of the measured elements that indicate imminent failure or serious
problems.
[0058] Proceeding to decisional step 230, control system 18
determines whether an alarm should be generated. More specifically,
an alarm may be a trend detected based on the analysis of the
information gathered indicating that while things are currently
operating within parameters that a problem may soon occur. For
example, tip dresser 32 may currently be operating within
acceptable operating parameters, but an analysis of tip dresser 32
may indicate that major replacement may soon be needed. Alarms may
be generated using historical data and/or the currently measured
data.
[0059] For another example, the measured temperature of tip dresser
22 may exceed the acceptable range of temperatures for a tip
dresser 22. This information can be used by a plant manager or
other administrator to schedule down time for monitoring station 20
and schedule other replacement and repair operations associated
with the monitoring station 20. For another example, arm 16 and
weld tips 22 may presently be operating within acceptable
parameters, but analysis of the data returned by monitoring station
20 may indicate that significant work my soon be needed. If a trend
is detected, then the YES branch of decisional step 230 leads to
step 232.
[0060] At step 232, an alarm is generated and communicated to an
appropriate person indicating the trend that has been detected. For
example, probable failure in the near future may be communicated to
a plant manager or operational supervisor via e-mail indicating the
imminent failure and the analysis which indicated the imminent
failure. The plant manager may then use the alarm to schedule
maintenance so as to decrease the down time and impact of the
repair. In one embodiment, the alarm includes the data which
triggered the alarm. Returning to step 230, if no alarms are to be
generated, then the NO branch leads to decisional step 234.
[0061] At decisional step 234, control system 18 determines whether
a fault exists. Typically, a fault indicates more immediate
problems than alarms. For example, imminent failure of weld tips 22
may be detected by control system 18 analyzing information from
monitoring station 20. If a fault is detected by control system 18,
then the YES branch of decisional step 234 leads to step 236. At
step 236, a fault is generated and communicated to an appropriate
person. In some embodiments, a fault may cause automatic shutdown
of the welding equipment. For example, imminent failure of the
cooling system for weld tips 22 may be communicated via a message
sent to a plant manager. In one embodiment, the fault includes the
data which triggered the fault. Returning to step 234, if no fault
is detected then the NO branch of decisional 234 leads to step
238.
[0062] At step 238, control system 18 records data received from
monitoring station 20 on storage 26. In one embodiment, data is
recorded by control system 18 in the manner consistent with ISO
9000 procedures. The method then ends.
[0063] Other changes, substitutions, and alterations are also
possible without departing from the spirit and scope of the present
invention, as defined by the following claims.
* * * * *