EP4097457A1 - Method for inspection of welds, in particular spot welds - Google Patents

Method for inspection of welds, in particular spot welds

Info

Publication number
EP4097457A1
EP4097457A1 EP21743371.3A EP21743371A EP4097457A1 EP 4097457 A1 EP4097457 A1 EP 4097457A1 EP 21743371 A EP21743371 A EP 21743371A EP 4097457 A1 EP4097457 A1 EP 4097457A1
Authority
EP
European Patent Office
Prior art keywords
weld
welds
area
inspection
particular spot
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Pending
Application number
EP21743371.3A
Other languages
German (de)
French (fr)
Inventor
Milan Honner
Lukás MUZIKA
Jan SROUB
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Zapadoceska Univerzita v Plzni
Original Assignee
Zapadoceska Univerzita v Plzni
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Zapadoceska Univerzita v Plzni filed Critical Zapadoceska Univerzita v Plzni
Publication of EP4097457A1 publication Critical patent/EP4097457A1/en
Pending legal-status Critical Current

Links

Classifications

    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N25/00—Investigating or analyzing materials by the use of thermal means
    • G01N25/72—Investigating presence of flaws
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N33/00—Investigating or analysing materials by specific methods not covered by groups G01N1/00 - G01N31/00
    • G01N33/20—Metals
    • G01N33/207—Welded or soldered joints; Solderability

Definitions

  • the invention relates to a method for inspecting welds, in particular spot welds, especially for products where spot welds occur in a large number.
  • Nondestructive and non-contact methods include methods based on the use of infrared radiation and heat transfer processes. They measure the temperature response of the front or back surface of the weld in response to the heat source.
  • the heat sources used are flash lamps, halogen lamps or infrared lasers. In all cases, the surface is heated in the area of the weld. The thermal process during and after the action of the heat source is measured by infradetectors or thermal imagers.
  • the recorded sequence of infrared images is computer processed by advanced algorithms that highlight small temperature differences and look for differences from the characteristics of high-quality welds.
  • the basic disadvantage which in principle complicates the distinction between high-quality and low- quality welds, is the action of the heat source on the surface of the material at the weld area, where the absorption of thermal radiation is affected in various ways by the previous welding process.
  • the original homogeneous photo-thermal properties of the surface are disturbed by the formation of oxide layers, adhering impurities and mechanical pressure. The result is an irregular spatially inhomogeneous absorption of a spatially homogeneous heat source.
  • Another disadvantage of the current state is the use of flash-lamps, with a short time of excitation heat pulse and small temperature differences in the controlled weld, the need to use expensive cooled infrared cameras and special algorithms demanding processing time and data volume.
  • the main problem is to achieve the spatial homogeneity of heating of a larger area and the dependence of the heat flux density on the distance of the heat source from the controlled surface.
  • the invention is based on the fact that inspection of welds, particularly spot welds, is not performed by direct determination of properties of the weld itself but the area around the weld whose optical properties of the surface are not affected by previous welding is heated and subsequently the spatial distribution of the time course of thermal radiation from the surface in the weld area is measured and it is determined whether the measured values fall within the range of values predetermined for a sufficiently high-quality weld.
  • the area around the weld may be the nearest closed area whose optical properties of the surface are not affected by previous welding, for example the nearest intermediate ring, the inner circle of which is spaced from the outer boundary of the weld in the range of 0.5 to 25 mm.
  • the area around the weld may be the nearest open area, the optical properties of the surface of which are not affected by the previous welding, this open area surrounding more than 270 degrees of a circle centered on the weld being inspected. This open area may consist of more parts.
  • the surroundings of the weld are preferably heated non-contactly and the spatial distribution of the time course of the thermal radiation from the surface in the area of the weld is preferably measured radiometrically non-contactly.
  • the spatial distribution of the time course of the thermal radiation from the surface in the area of the weld is preferably measured in the range of 0.01 to 10 seconds.
  • Values falling within the range of values predetermined for a sufficiently high-quality weld are determined from a sample of high-quality welds or by computer simulation.
  • the basic advantage of the method of quality control of welds according to the invention is that the heating acts in the vicinity of the weld, the optical properties of the surface of which are not affected by the previous welding. This ensures spatially uniform heating within one controlled weld and the repeatability of the absorbed power within a number of different welds of the same type.
  • the process of inspecting the welds significantly simplifies the process of automating the inspection of the same type of welds occurring on the same welded parts.
  • the advantage of the method according to the invention is that it is possible to achieve larger temperature differences in further heating times and thus use orders of magnitude cheaper types of bolometric uncooled thermal imagers instead of faster and more expensive photon thermal imagers which require additional active cooling.
  • the heating process which creates temperature differences between welds with different defects, has only taken place for a small part of the total inspection time.
  • the process of differentiating welds, automating machine evaluation, and large data processing problems are greatly simplified by using the continuous laser action and by using the evaluation conducted on temperatures during the heating phase instead of the cooling phase after the short heating pulse.
  • the advantage of the method of quality control of welds according to the invention is the possibility to define different power, time and space effects of non-contact heat source and thus to solve optimal parameters of control of different welds usually occurring on one welded part.
  • the method of inspection of welds according to the invention makes it possible to use overall simpler and cheaper components for inspection of welds, and thus investment requirements for the entire inspection workplace are significantly saved.
  • FIG. 1 shows schematically an apparatus for carrying out the weld inspection method and heat fluxes associated with heating and measuring the temperature response
  • Fig. 2 shows schematically a plan view of the weld and its surroundings of Fig. 1
  • Fig. 3 shows the heat fluxes in the inspected welded material
  • Fig. 4 shows the spatial heat fluxes on the material surface in the area of the weld and its surroundings
  • Fig. 5 shows the spatial temperature distribution at the material surface in the weld cross-section
  • Fig. 6 shows the time course of the heat flux action divided into heating phase and cooling phase
  • Fig. 7 shows time courses of surface temperature at weld area and in its vicinity
  • Fig. 1 shows schematically an apparatus for carrying out the weld inspection method and heat fluxes associated with heating and measuring the temperature response
  • Fig. 2 shows schematically a plan view of the weld and its surroundings of Fig. 1
  • Fig. 3 shows the heat fluxes in the inspected welded material
  • Fig. 4 shows
  • Fig. 8 shows evaluation of weld quality by measured surface temperature in the weld area
  • Fig. 9 shows schematically the inspection of spot welds
  • Fig. 10 shows schematically the inspection of linear welds
  • Fig. 11 shows schematically the inspection of spatially characteristic welds
  • Fig. 12 shows schematically the implementation of an optomechanical member by means of lenses or apertures
  • Fig. 13 shows schematically the implementation of an optomechanical member by means of mirrors using a scanning head
  • Fig. 14 shows schematically a weld testing device ensuring the positioning of the measuring system and the inspected weld in the desired relative position.
  • the inspection of the welds according to the invention can be carried out on a device which is schematically shown in Fig.l. Heating is provided by a laser source 1, an infradetector system 2 is used to measure the temperature response, control, communication, evaluation and display are provided by a control unit 3.
  • the inspected welded part consists of an upper plate 4, lower plate 5, and the actual joint is a weld nugget 6.
  • the testing device contains an optomechanical member 9, which ensures a defined spatial and temporal action of the laser beam on the vicinity of the weld.
  • the surface around the weld nugget 6 is shown in Fig. 2.
  • the heating heat flux 7 acts on the top plate 4 in the heated area 14 and provides heating around the weld.
  • the heating heat flux 7 can also act in the area of the weld, when the predominant part of the power of the laser source 1 must act in the vicinity of the weld, the optical properties of which are not affected by previous welding.
  • the radiated heat flux 8 is sensed by the infradetector system 2 from the measured area 15, which includes the weld area and its vicinity.
  • the heat fluxes in the material during heating are shown in Fig.3.
  • the heating heat flux 7 acts around the weld.
  • the laser beam is absorbed by the surface of the material and causes a rise in temperature around the weld.
  • the heat propagates mainly through the top plate 4 to the weld area and is dissipated through the weld nugget 6 to the bottom plate 5.
  • This described thermal process causes heating of the weld area surface, where the temperature is significantly affected by thermal characteristics of the welded joint.
  • the heating heat flux 7 acts spatially in the heated area 14 around the weld nugget 6, preferably no heating heat flux 7 is effective in the region of the welding nugget 6 itself.
  • Fig. 5 From a time point of view, the process of action of the laser source is seen in Fig. 5. It is divided into a heating phase 16, when a laser beam a laser beam strikes the surface around the weld and the surface is heated, and a cooling phase 17, when the surface of the material cools down after the laser source is switched off.
  • Fig.6 The spatial distribution of the surface temperature of the material in the measured area 15 in the weld cross-section at time tr during heating is shown in Fig.6.
  • a maximum temperature 10 the value of which is most influenced by the laser power and thermal properties of the top plate 4.
  • Fig. 7 schematically shows the time course of temperature in around the weld 12, i.e. in the area of laser heating xp in the vicinity of the weld nugget 6 and the time course of temperature in the weld 13, i.e. in the area of the weld itself XT, by means of which the basic evaluation of the weld quality takes place.
  • the method of evaluating the quality of the weld by means of the measured surface temperature in the weld area is shown in Fig.8.
  • the band of appropriate temperatures 20 is determined.
  • the area for given weld parameters, especially thickness of top plate 4 and bottom plate 5, size of weld nugget 6, and heating parameters, especially power of laser source 1 and size of area, where the heating heat flux 7 acts, corresponds to high-quality welds. This area is marked as “OK” in Fig. 8 and corresponds to the temperature of high quality weld 18.
  • the surface temperature is generally measured non-contactly by means of infradetectors, which detect primarily the intensity of the radiated heat flux 8 emitted by the surface of the material.
  • the temperature is evaluated by quantification of the radiation processes involved, including the values of the emissivity of the measured surface, the temperature of the radiation environment and the transmissivity of the atmosphere. The method of determining weld quality is therefore the same whether the temperature value or the source signal value of the measured heat flux is used for its evaluation.
  • Figs. 9 to 11 The inspection of welds by the method according to the described invention can be used for welds of different shapes and sizes produced by different technologies. This is shown schematically in Figs. 9 to 11. These can be spot welds formed by resistance welding technology, as shown in Fig. 9, or line welds formed by laser technology with a technological head, as shown in Fig. 10, or spatially characteristic welds formed by so-called remote laser technology with a scanning head, as shown in Fig. 11.
  • the shape of the heated area 14 where the laser beam acts corresponds to the shape and size of the inspected weld nugget 6 and also to the shape and size of the inspected welded part, namely the presence of material edges or other welds.
  • the spatial distribution of the heat flow in this heated area 14 may not be homogeneous, but may respect the above-mentioned characteristics of the inspected weld.
  • the heated area 14 need not only be in the immediate vicinity of the weld and need not be a closed area, but must always act so that the heating process and measurement of temperature response meet the needs of accuracy and repeatability to distinguish high quality and poor quality welds.
  • the technical implementation of the optomechanical member 9 ensuring the spatial and temporal action of the laser beam on the surface around the weld can be performed in various ways, as schematically shown in Fig. 12 and Fig. 13. This may involve the principles of shaping the laser beam by lenses 23 or apertures 24 in Fig. 12, or the principles of positioning the laser beam using mirrors 25 for example by scanning head in Fig. 13.
  • the invention can be used especially for workplaces where a large number of spot welds are performed and their quality needs to be inspected quickly and efficiently.

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  • Chemical & Material Sciences (AREA)
  • Health & Medical Sciences (AREA)
  • Life Sciences & Earth Sciences (AREA)
  • General Health & Medical Sciences (AREA)
  • Analytical Chemistry (AREA)
  • Biochemistry (AREA)
  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Immunology (AREA)
  • Pathology (AREA)
  • Engineering & Computer Science (AREA)
  • Food Science & Technology (AREA)
  • Medicinal Chemistry (AREA)
  • Investigating Or Analyzing Materials Using Thermal Means (AREA)

Abstract

The inspection of welds, particularly spot welds, is not performed by direct determination of properties of the weld itself but the area around the weld whose optical properties of the surface are not affected by previous welding is heated and subsequently the spatial distribution of the time course of thermal radiation from the surface in the weld area is measured and it is determined whether the measured values fall within the range of values predetermined for a sufficiently high-quality weld.

Description

Method for inspection of welds, in particular spot welds
Field
The invention relates to a method for inspecting welds, in particular spot welds, especially for products where spot welds occur in a large number.
Prior art
At present, spot welds are inspected in both destructive and non-destructive ways. Nondestructive and non-contact methods include methods based on the use of infrared radiation and heat transfer processes. They measure the temperature response of the front or back surface of the weld in response to the heat source. The heat sources used are flash lamps, halogen lamps or infrared lasers. In all cases, the surface is heated in the area of the weld. The thermal process during and after the action of the heat source is measured by infradetectors or thermal imagers.
The recorded sequence of infrared images is computer processed by advanced algorithms that highlight small temperature differences and look for differences from the characteristics of high- quality welds.
These methods have their advantages over others, but also a number of disadvantages. The basic disadvantage, which in principle complicates the distinction between high-quality and low- quality welds, is the action of the heat source on the surface of the material at the weld area, where the absorption of thermal radiation is affected in various ways by the previous welding process. The original homogeneous photo-thermal properties of the surface are disturbed by the formation of oxide layers, adhering impurities and mechanical pressure. The result is an irregular spatially inhomogeneous absorption of a spatially homogeneous heat source. These phenomena in the thermal process overlap the thermal phenomena caused by poor weld quality and therefore significantly prevent the automated evaluation of poor quality welds.
Another disadvantage of the current state is the use of flash-lamps, with a short time of excitation heat pulse and small temperature differences in the controlled weld, the need to use expensive cooled infrared cameras and special algorithms demanding processing time and data volume. In the case of the use of lasers, the main problem is to achieve the spatial homogeneity of heating of a larger area and the dependence of the heat flux density on the distance of the heat source from the controlled surface. of the invention
The invention is based on the fact that inspection of welds, particularly spot welds, is not performed by direct determination of properties of the weld itself but the area around the weld whose optical properties of the surface are not affected by previous welding is heated and subsequently the spatial distribution of the time course of thermal radiation from the surface in the weld area is measured and it is determined whether the measured values fall within the range of values predetermined for a sufficiently high-quality weld.
The area around the weld may be the nearest closed area whose optical properties of the surface are not affected by previous welding, for example the nearest intermediate ring, the inner circle of which is spaced from the outer boundary of the weld in the range of 0.5 to 25 mm.
The area around the weld may be the nearest open area, the optical properties of the surface of which are not affected by the previous welding, this open area surrounding more than 270 degrees of a circle centered on the weld being inspected. This open area may consist of more parts.
The surroundings of the weld are preferably heated non-contactly and the spatial distribution of the time course of the thermal radiation from the surface in the area of the weld is preferably measured radiometrically non-contactly.
The spatial distribution of the time course of the thermal radiation from the surface in the area of the weld is preferably measured in the range of 0.01 to 10 seconds.
Values falling within the range of values predetermined for a sufficiently high-quality weld are determined from a sample of high-quality welds or by computer simulation.
The basic advantage of the method of quality control of welds according to the invention is that the heating acts in the vicinity of the weld, the optical properties of the surface of which are not affected by the previous welding. This ensures spatially uniform heating within one controlled weld and the repeatability of the absorbed power within a number of different welds of the same type.
In the current state of the art, the surface including the weld itself was also heated, and thus, due to the regularly occurring impurities on the surface of the weld itself, there was a significant unevenness and unrepeatability of heating of the measured area.
By avoiding heating the surface of the welds themselves, which are often affected in various and irregular ways by previous welding, the process of inspecting the welds significantly simplifies the process of automating the inspection of the same type of welds occurring on the same welded parts.
The advantage of the method according to the invention is that it is possible to achieve larger temperature differences in further heating times and thus use orders of magnitude cheaper types of bolometric uncooled thermal imagers instead of faster and more expensive photon thermal imagers which require additional active cooling. In the current state of the art, the heating process, which creates temperature differences between welds with different defects, has only taken place for a small part of the total inspection time. The process of differentiating welds, automating machine evaluation, and large data processing problems are greatly simplified by using the continuous laser action and by using the evaluation conducted on temperatures during the heating phase instead of the cooling phase after the short heating pulse.
The advantage of the method of quality control of welds according to the invention is the possibility to define different power, time and space effects of non-contact heat source and thus to solve optimal parameters of control of different welds usually occurring on one welded part.
The method of inspection of welds according to the invention makes it possible to use overall simpler and cheaper components for inspection of welds, and thus investment requirements for the entire inspection workplace are significantly saved.
Brief description of the drawings
An exemplary embodiment of the invention is shown in the accompanying figures, in which Fig. 1 shows schematically an apparatus for carrying out the weld inspection method and heat fluxes associated with heating and measuring the temperature response; Fig. 2 shows schematically a plan view of the weld and its surroundings of Fig. 1; Fig. 3 shows the heat fluxes in the inspected welded material; Fig. 4 shows the spatial heat fluxes on the material surface in the area of the weld and its surroundings; Fig. 5 shows the spatial temperature distribution at the material surface in the weld cross-section; Fig. 6 shows the time course of the heat flux action divided into heating phase and cooling phase; Fig. 7 shows time courses of surface temperature at weld area and in its vicinity; Fig. 8 shows evaluation of weld quality by measured surface temperature in the weld area; Fig. 9 shows schematically the inspection of spot welds; Fig. 10 shows schematically the inspection of linear welds; Fig. 11 shows schematically the inspection of spatially characteristic welds; Fig. 12 shows schematically the implementation of an optomechanical member by means of lenses or apertures; Fig. 13 shows schematically the implementation of an optomechanical member by means of mirrors using a scanning head and Fig. 14 shows schematically a weld testing device ensuring the positioning of the measuring system and the inspected weld in the desired relative position.
Exemplary embodiments of the invention
The inspection of the welds according to the invention can be carried out on a device which is schematically shown in Fig.l. Heating is provided by a laser source 1, an infradetector system 2 is used to measure the temperature response, control, communication, evaluation and display are provided by a control unit 3. The inspected welded part consists of an upper plate 4, lower plate 5, and the actual joint is a weld nugget 6. The testing device contains an optomechanical member 9, which ensures a defined spatial and temporal action of the laser beam on the vicinity of the weld.
The surface around the weld nugget 6 is shown in Fig. 2. The heating heat flux 7 acts on the top plate 4 in the heated area 14 and provides heating around the weld. However, in the context of the invention, the heating heat flux 7 can also act in the area of the weld, when the predominant part of the power of the laser source 1 must act in the vicinity of the weld, the optical properties of which are not affected by previous welding. The radiated heat flux 8 is sensed by the infradetector system 2 from the measured area 15, which includes the weld area and its vicinity.
The heat fluxes in the material during heating are shown in Fig.3. The heating heat flux 7 acts around the weld. The laser beam is absorbed by the surface of the material and causes a rise in temperature around the weld. Subsequently, the heat propagates mainly through the top plate 4 to the weld area and is dissipated through the weld nugget 6 to the bottom plate 5. This described thermal process causes heating of the weld area surface, where the temperature is significantly affected by thermal characteristics of the welded joint.
Spatial distribution of heat fluxes and heat flux time curves on the surface of the material in the weld area and its vicinity are schematically shown in Fig 4 and Fig. 5. The heating heat flux 7 acts spatially in the heated area 14 around the weld nugget 6, preferably no heating heat flux 7 is effective in the region of the welding nugget 6 itself.
From a time point of view, the process of action of the laser source is seen in Fig. 5. It is divided into a heating phase 16, when a laser beam a laser beam strikes the surface around the weld and the surface is heated, and a cooling phase 17, when the surface of the material cools down after the laser source is switched off.
The spatial temperature profiles and time temperature profiles on the surface of the material in the area of the weld and its vicinity are schematically shown in Fig. 6 and Fig. 7.
The spatial distribution of the surface temperature of the material in the measured area 15 in the weld cross-section at time tr during heating is shown in Fig.6. In the heated area 14 around the weld nugget 6 there is a maximum temperature 10, the value of which is most influenced by the laser power and thermal properties of the top plate 4.
At the location of the weld nugget 6, the level of the surface temperature 11 is influenced mainly by the thermal characteristics of the weld nugget 6, which indicate the quality of the weld. Next, Fig. 7 schematically shows the time course of temperature in around the weld 12, i.e. in the area of laser heating xp in the vicinity of the weld nugget 6 and the time course of temperature in the weld 13, i.e. in the area of the weld itself XT, by means of which the basic evaluation of the weld quality takes place.
The method of evaluating the quality of the weld by means of the measured surface temperature in the weld area is shown in Fig.8. By means of experimental calibration or by computer simulation of weld variants, the band of appropriate temperatures 20 is determined. The area for given weld parameters, especially thickness of top plate 4 and bottom plate 5, size of weld nugget 6, and heating parameters, especially power of laser source 1 and size of area, where the heating heat flux 7 acts, corresponds to high-quality welds. This area is marked as “OK” in Fig. 8 and corresponds to the temperature of high quality weld 18.
If the temperature is higher, we get to the band of higher temperatures 21, which indicates a poor quality weld, which dissipates less heat through the weld nugget 6 and the bottom plate 5 than a high quality weld. If the temperature is lower, we get to the band of lower temperatures 22, so the result of the inspection is also an unsatisfactory condition, which is marked as "NOK" in Fig.
8, mainly due to failure to perform the required heating around the weld. These areas represent temperature of poor quality weld 19.
The surface temperature is generally measured non-contactly by means of infradetectors, which detect primarily the intensity of the radiated heat flux 8 emitted by the surface of the material. The temperature is evaluated by quantification of the radiation processes involved, including the values of the emissivity of the measured surface, the temperature of the radiation environment and the transmissivity of the atmosphere. The method of determining weld quality is therefore the same whether the temperature value or the source signal value of the measured heat flux is used for its evaluation.
The inspection of welds by the method according to the described invention can be used for welds of different shapes and sizes produced by different technologies. This is shown schematically in Figs. 9 to 11. These can be spot welds formed by resistance welding technology, as shown in Fig. 9, or line welds formed by laser technology with a technological head, as shown in Fig. 10, or spatially characteristic welds formed by so-called remote laser technology with a scanning head, as shown in Fig. 11.
The shape of the heated area 14 where the laser beam acts corresponds to the shape and size of the inspected weld nugget 6 and also to the shape and size of the inspected welded part, namely the presence of material edges or other welds. The spatial distribution of the heat flow in this heated area 14 may not be homogeneous, but may respect the above-mentioned characteristics of the inspected weld. The heated area 14 need not only be in the immediate vicinity of the weld and need not be a closed area, but must always act so that the heating process and measurement of temperature response meet the needs of accuracy and repeatability to distinguish high quality and poor quality welds.
The technical implementation of the optomechanical member 9 ensuring the spatial and temporal action of the laser beam on the surface around the weld can be performed in various ways, as schematically shown in Fig. 12 and Fig. 13. This may involve the principles of shaping the laser beam by lenses 23 or apertures 24 in Fig. 12, or the principles of positioning the laser beam using mirrors 25 for example by scanning head in Fig. 13.
Usually, it is necessary to inspect several different welds spatially located in different places on one welded part.
In such a case, it is necessary to ensure the desired relative position of the measuring system and inspected welded part. This can be ensured, as shown in Fig. 14, by placing the attachment of the measuring system 26 on the arm of the industrial robot 28 or on a gantry manipulator, which move the measuring part of the device around the statically located welded part using the attachment of the inspected welded part 27. The opposite method is also technically feasible, where inspected welded parts are positioned to a stationary measuring system by means of an industrial robot or another conveyor.
Industrial
The invention can be used especially for workplaces where a large number of spot welds are performed and their quality needs to be inspected quickly and efficiently.
LIST OF REFERENCE MARKS
1 - laser source
2 - infradetector system
3 - control unit
4 - top plate
5 - bottom plate
6 - weld nugget
7 - heating heat flux
8 - radiated heat flux
9 - optomechanical member
10 - maximum temperature
11 - surface temperature
12 - time course of temperature around the weld
13 - time course of the temperature in the weld
14 - heated area
15 - measured area
16 - heating phase
17 - cooling phase
18 - temperature of high quality weld
19 - temperature of poor quality weld
20 - band of appropriate temperatures
21 - band of higher temperatures
22 - band of lower temperatures
23 - lens
24 - aperture
25 - mirror
26 - attachment of the measuring system
27 - attachment of the inspected welded part
28 - industrial robot

Claims

1. A method for inspection of welds, in particular spot welds, characterized in that the area around the weld whose optical properties of the surface are not affected by previous welding is heated and subsequently the spatial distribution of the time course of thermal radiation from the surface in the weld area is measured and it is determined whether the measured values fall within the range of values predetermined for a sufficiently high-quality weld
2. A method for inspection of welds, in particular spot welds, according to Claim 1, characterized in that the area around the weld is the nearest closed area, the optical properties of the surface of which are not affected by the previous welding.
3. A method for inspection of welds, in particular spot welds, according to Claim 2, characterized in that the area around the weld is the nearest intermediate ring, the optical properties of the surface of which are not affected by previous welding and whose inner circle is spaced from the outer boundary of the weld by 0.5 to 25 mm.
4. A method of inspection of welds, in particular spot welds, according to Claim 1, characterized in that the area around the weld is the nearest unclosed area the optical properties of the surface of which are not affected by previous welding and this unclosed area surrounds more than 270 degrees of circle centered in the inspected weld.
5. A method for inspection of welds, in particular spot welds, according to Claim 4, characterized in that the unclosed area the optical properties of the surface of which are not affected by previous welding and surrounds more than 270 degrees of circle centered in the inspected weld consists of at least two parts.
6. A method for inspection of welds, in particular spot welds, according to Claim 1, characterized in that the area around the weld is heated in a contactless way.
7. A method for inspection of welds, in particular spot welds, according to Claim 1, characterized in that the spatial distribution of the time course of the thermal radiation from the surface in the weld area is measured radiometrically in a contactless way.
8. A method for inspection of welds, in particular spot welds, according to Claim 1, characterized in that the spatial distribution of the time course of the thermal radiation from the surface in the area of the weld is measured in the range from 0.01 to 10 seconds.
9. A method for inspection of welds, in particular spot welds, according to Claim 1, characterized in that the values falling within the range of values predetermined for a sufficiently high-quality weld are determined from a set of high-quality welds or by computer simulation.
8
EP21743371.3A 2020-10-27 2021-06-22 Method for inspection of welds, in particular spot welds Pending EP4097457A1 (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
CZ2020582A CZ2020582A3 (en) 2020-10-27 2020-10-27 Method of inspecting welds, especially spot welds
PCT/CZ2021/050069 WO2022089675A1 (en) 2020-10-27 2021-06-22 Method for inspection of welds, in particular spot welds

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EP4097457A1 true EP4097457A1 (en) 2022-12-07

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JP (1) JP2023546637A (en)
CZ (1) CZ2020582A3 (en)
WO (1) WO2022089675A1 (en)

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