阅读说明：本技术 具有用于接触钎焊焊丝并与检测器相关联地阻挡激光束的第一部分的夹具的激光钎焊系统、监测激光钎焊系统的方法 (Laser brazing system having a clamp for contacting a brazing wire and blocking a first portion of a laser beam in association with a detector, method of monitoring a laser brazing system ) 是由 弗雷德里克·拉格纳森 于 2017-04-19 设计创作，主要内容包括：本发明涉及一种激光钎焊系统(100),其包括：钎焊工具(110),该钎焊工具(110)具有被构造成沿着辐射路径(RP)发射激光束(114)的激光器(112)；和钎焊焊丝工具(120),该钎焊焊丝工具(120)被构造成沿着与激光束(114)相交的焊丝路径(WP)引导钎焊焊丝(122)。该系统(100)包括：夹具(130),该夹具(130)包括第一对准表面(132a)和第一阻挡表面(134a),其中,第一对准表面(132a)被构造成与钎焊焊丝(122)接触,同时第一阻挡表面(134a)阻挡所发射的激光束(114)的至少第一部分；以及检测器(140),该检测器(140)布置在所述辐射路径(RP)中,并且被构造成检测所述激光束的越过夹具(130)的所发射的光。还提供了一种监测激光钎焊系统的方法。(The invention relates to a laser brazing system (100) comprising: a brazing tool (110), the brazing tool (110) having a laser (112) configured to emit a laser beam (114) along a Radiation Path (RP); and a brazing wire tool (120), the brazing wire tool (120) configured to direct a brazing wire (122) along a Wire Path (WP) that intersects the laser beam (114). The system (100) comprises: a clamp (130), the clamp (130) comprising a first alignment surface (132a) and a first blocking surface (134a), wherein the first alignment surface (132a) is configured to contact the brazing wire (122) while the first blocking surface (134a) blocks at least a first portion of the emitted laser beam (114); and a detector (140), the detector (140) being arranged in the Radiation Path (RP) and being configured to detect emitted light of the laser beam across the clamp (130). A method of monitoring a laser brazing system is also provided.)

1. A laser brazing system (100), comprising: a brazing tool (110), the brazing tool (110) having a laser (112), the laser (112) being configured to emit a laser beam (114) along a Radiation Path (RP); and a brazing wire tool (120), the brazing wire tool (120) configured to direct a brazing wire (122) along a Wire Path (WP) that intersects the laser beam (114),

It is characterized in that

A clamp (130), the clamp (130) comprising a first alignment surface (132a) and a first blocking surface (134a), wherein the first alignment surface (132a) is configured to contact the brazing wire (122) while the first blocking surface (134a) blocks at least a first portion of the emitted laser beam (114); and

A detector (140), the detector (140) being arranged in the Radiation Path (RP) and configured to detect emitted light of the laser beam that passes over the clamp (130).

2. the brazing system (100) according to claim 1, wherein the fixture (130) further comprises a second alignment surface (132b) facing a different direction than the first alignment surface (132a), and a second blocking surface (134b) facing a different direction than the first blocking surface (132 b).

3. The brazing system (100) of claim 2, wherein the second alignment surface (132b) is configured to contact the brazing wire (122) while the second blocking surface (134b) blocks at least a second portion of the emitted laser beam (114).

4. the brazing system (100) of any one of the preceding claims, further comprising a control unit (150), the control unit (150) being configured to receive a first signal (S1) from the detector (140) and to determine a position of the brazing wire (122) relative to the Radiation Path (RP) based on the signal (S), the first signal (S1) comprising information about an amount of laser light detected when the first blocking surface (134a) blocks at least a first portion of the emitted laser beam (114).

5. The brazing system (100) according to claim 4, wherein the control unit (150) is configured to: determining a position of the brazing wire (122) by determining whether the brazing wire (122) is located within or outside a predetermined area.

6. The brazing system (100) according to claim 5, wherein the control unit (150) is configured to compare the information of the first signal (S1) with a pre-stored reference value.

7. The brazing system (100) according to claim 6, wherein the reference value is at least one threshold value corresponding to the brazing wire (122) being outside the predetermined area.

8. The brazing system (100) according to claim 6 or 7, wherein the reference value corresponds to an amount of detected light when the brazing wire (122) is arranged in its desired position.

9. The brazing system (100) according to any one of claims 5 to 8, wherein the control unit (150) is further configured to receive a second signal (S2) from the detector (140), the second signal (S2) comprising information about an amount of laser light detected when the second blocking surface (134b) blocks at least a second portion of the emitted laser beam (114).

10. The brazing system (100) of claim 9, wherein the control unit (150) is configured to determine a ratio from the first signal (S1) and the second signal (S2) and to compare the determined ratio with the reference value.

11. Brazing system (100) according to any one of the preceding claims, wherein the clamp (130) is connected to a drive unit (160), and wherein the control unit (150) is configured to: -moving the clamp (130) to and from a first and/or a second measuring position by controlling the drive unit (160).

12. A method for monitoring a laser brazing system (100), comprising:

Activating the laser soldering tool (110) to emit a laser beam (114) along a Radiation Path (RP),

Guiding a brazing wire (122) along a Wire Path (WP) intersecting the Radiation Path (RP),

Blocking at least a first portion of the emitted laser beam (114) by a fixture (130), and

Detecting emitted light of the laser beam across the fixture (130).

13. the method of claim 12, wherein blocking at least a first portion of the emitted laser beam comprises:

Arranging the clamp (130) in a first measurement position in which a first alignment surface (132a) is in contact with the brazing wire (122) and a first blocking surface (134a) blocks at least a first portion of the emitted laser beam (114).

14. the method of claim 12 or 13, further comprising: the detected amount of light is compared with a pre-stored reference value.

15. the method of claim 14, further comprising: determining a position of the brazing wire (122) relative to the Radiation Path (RP) based on a comparison between the detected amount of light and the reference value.

16. The method of claim 15, further comprising: determining whether the brazing wire (122) is located within or outside a predetermined area.

17. The method of any of claims 14-16, wherein the reference value corresponds to an amount of light detected when the brazing wire (122) is disposed in its desired position.

18. The method according to any one of claims 12-17, further comprising: blocking a second portion of the emitted laser beam (114) by the fixture (130).

19. The method of claims 13 and 18, wherein blocking the second portion of the emitted laser beam comprises:

Arranging the clamp (130) in a second measurement position in which a second alignment surface (132b) facing a different direction than the first alignment surface (132a) contacts the brazing wire (122) and a second blocking surface (134b) facing a different direction than the first blocking surface (134a) blocks at least a second portion of the emitted laser beam (114).

20. The method of claim 19, further comprising: determining a ratio from a first signal and a second signal, and comparing the determined ratio with a reference value, the first signal comprising information related to the amount of light detected when the jig (130) is arranged in the first measurement position, the second signal comprising information related to the amount of light detected when the jig (130) is arranged in the second measurement position.

Technical Field

The present invention relates to a laser brazing system, and a method of monitoring a laser brazing system.

The invention can be applied in the manufacture and production lines of various components, for example, for joining sheet metal or panels in the automotive industry, including heavy vehicles such as trucks, buses and construction equipment. Although the invention will be described in relation to a truck, the invention is not limited to this particular vehicle, but may also be used in other applications.

Background

Laser brazing is commonly used in automated mass production lines. Using this technique, two sheets or panels are joined together by a filler material, which is typically provided as a welding wire. The laser is directed to irradiate a filler material wire which then melts and flows to join the two sheets or panels. Thus, two sheets or panels can be bonded together without the need to sufficiently melt the sheets or panels.

During laser brazing, the position of the brazing wire relative to the laser beam is important; typically, the position of the welding wire is set to a predetermined value, e.g., centered with the laser beam. However, the position of the welding wire may change unexpectedly, for example, if the welding wire gets stuck or a failure occurs in a brazing tool component. If the position of the welding wire is outside the predetermined working range, the braze weld will be defective and the brazed part must be repaired or even discarded.

In order to ensure correct operation of the soldering tool, the wire position may be checked manually after a certain number of soldering operations. This monitoring will have a negative impact on the yield, since the process has to be stopped during this inspection. Also, in the case where the wire is incorrectly positioned, there is a possibility that several faulty portions are generated before misalignment (misalignment) of the wire is detected.

JPH-06344163a describes a system configured to: whether the welding wire is properly positioned is determined by providing a visible laser beam that converges to the desired wire position. The optical detector is arranged to detect the laser light reflected from the welding wire and, by analysing the amount of light detected, it can be determined whether the welding wire is correctly positioned.

Although it can be determined whether the wire is properly positioned, an auxiliary laser source is required. This is due to the fact that: if the original laser is used to monitor the position of the wire, the wire will melt. Accordingly, it would be advantageous to provide a laser brazing system that is less complex.

Disclosure of Invention

It is an object of the present invention to provide a laser brazing system that can be used to automatically monitor the position of a brazing wire in a simple and reliable manner.

according to a first aspect, the object is achieved by a laser brazing system according to claim 1. According to a second aspect, the object is achieved by a method for monitoring a laser brazing system according to claim 12. However, it should be appreciated that the method for monitoring may be used with any brazing tool in which the position of the brazing wire should be fixed relative to the laser beam.

By providing a clamp that blocks a portion of the emitted laser beam while shielding (shields off) the wire, the position of the wire can be monitored without the use of additional lasers.

According to one embodiment, the fixture further comprises a second alignment surface facing a different direction than the first alignment surface, and a second blocking surface facing a different direction than the first blocking surface. Thus, rather than using a pre-stored reference value, the wire position may be monitored by comparing the light detected when the first blocking surface and laser beam are aligned with the light detected when the second blocking surface and laser beam are aligned.

The second alignment surface may be configured to contact the brazing wire while the second blocking surface blocks at least a second portion of the emitted laser beam.

In one embodiment, the laser brazing system further comprises a control unit configured to receive a first signal from the detector, the first signal comprising information about the amount of laser light detected when the first blocking surface blocks at least a first portion of the emitted laser beam, and to determine the position of the brazing wire relative to the radiation path based on the signal. Thus, the position of the brazing wire relative to the laser beam can be automatically determined.

In one embodiment, the control unit is configured to determine the position of the brazing wire by determining whether the brazing wire is located within or outside of a predetermined range. This allows the operator to set the boundaries (boundaries) within which the brazing wire is allowed to be located.

In one embodiment, the control unit is configured to compare the information of the first signal with a pre-stored reference value. Thus, it can be automatically determined whether the position of the brazing wire is within a predetermined acceptable range.

In one embodiment, the reference value is at least one threshold value corresponding to the brazing wire being outside the predetermined range, and the reference value may correspond to an amount of light detected when the brazing wire is arranged in its desired position.

according to an embodiment, the control unit is further configured to receive a second signal from the detector, the second signal comprising information on the amount of laser light detected when the second blocking surface blocks at least a second portion of the emitted laser beam. The determination of the position of the welding wire can be improved since the risk of measuring faults is reduced.

In one embodiment, the control unit is configured to determine a ratio from the first and second signals and to compare the determined ratio with a reference value. This comparison of the ratios will provide a very simple and reliable criterion to determine whether the brazing wire is correctly positioned.

In one embodiment, the clamp is connected to a drive unit, and the control unit is configured to: the gripper is moved to and from the first and/or second measuring position by controlling the drive unit. Thus, automatic control of the position of the clamp is provided. It should be noted, however, that in an alternative embodiment the position of the clamp is fixed, whereby the soldering tool is movable relative to the clamp.

According to a second aspect, a method for monitoring a laser brazing system is provided. The laser brazing system includes: a laser brazing tool configured to emit a laser beam along a radiation path; and a brazing wire guided along a wire path intersecting the radiation path. The method comprises the following steps: blocking, by the fixture, at least a first portion of the emitted laser beam; and measuring an amount of emitted light of the laser beam across the fixture.

In one embodiment, the step of blocking at least a first portion of the emitted laser beam comprises: the clamp is arranged in a first measuring position in which the first alignment surface is in contact with the brazing wire and the first blocking surface blocks at least a first portion of the emitted laser beam.

In one embodiment, the method further comprises: the detected amount of light is compared with a pre-stored reference value.

According to one embodiment, the method further comprises: determining a position of the brazing wire relative to the radiation path based on a comparison between the detected amount of light and the reference value. The method may further determine whether the brazing wire is located within or outside the predetermined area.

In one embodiment, the reference value corresponds to the amount of light detected when the brazing wire is arranged in its desired position.

In one embodiment, the method further comprises: blocking, by the fixture, a second portion of the emitted laser beam. Such blocking of the second portion of the emitted laser beam may comprise: the jig is arranged in a second measuring position in which a second alignment surface facing a different direction from the first alignment surface is in contact with the brazing wire, and in which a second blocking surface facing a different direction from the first blocking surface blocks at least a second portion of the emitted laser beam.

According to one embodiment, the method further comprises: determining a ratio from a first signal comprising information about the amount of light detected when the fixture is arranged in a first measurement position and a second signal comprising information about the amount of light detected when the fixture is arranged in a second measurement position; and comparing the determined ratio with a reference value.

further advantages and advantageous features of the invention are disclosed in the following description and in the dependent claims.

Drawings

With reference to the accompanying drawings, the following is a more detailed description of embodiments of the invention cited as examples.

In these figures:

Figure 1 is a schematic view of a truck,

Figure 2a is an isometric view of two sheets joined by laser brazing,

Figure 2b is a side view of the brazing wire centered with respect to the laser beam,

Figure 2c is a side view of the brazing wire positioned off-center with respect to the laser beam,

Fig. 3a is a side view of a laser brazing system according to one embodiment, wherein the brazing wire is centered with respect to the laser beam,

Fig. 3b is a side view of the laser brazing system shown in fig. 3a, however, the brazing wire is positioned off-center with respect to the laser beam,

Fig. 4 is an isometric view of a laser brazing system according to one embodiment, wherein the jig is in a first measuring position,

fig. 5 is an isometric view of the laser brazing system shown in fig. 4, with the jig in a second measuring position,

FIG. 6 is a graph showing the amount of laser light measured as a function of braze wire position, and

FIG. 7 is a schematic diagram of a method for monitoring a laser brazing system according to one embodiment.

Detailed Description

starting with fig. 1, a vehicle 1, here in the form of a truck, is shown. The truck 1 has a cab 2, which cab 2 is manufactured by joining together several plate-like sections 10. At least one of these sections 10 is produced by laser brazing.

In fig. 2, the general principle of laser brazing is shown. The first plate-like material 10a is arranged close to or in contact with the second plate-like material 10 b. The first plate-like material 10a and the second plate-like material 10b may be in the form of, for example, sheet metal or other suitable structures. In order to join the first plate-like material 10a to the second plate-like material 10b to form the section 10, a brazing wire 122 is arranged at the interface between the first plate-like material 10a and the second plate-like material 10 b. The brazing wire 122 is further irradiated by a laser beam 114, which laser beam 114 is configured to melt said brazing wire 122 and to provide heating of the sheet material 10a, 10 b. When the brazing wire 122 is melted, the brazing wire 122 will flow at the interface between the first sheet material 10a and the second sheet material 10b to ensure proper bonding of the materials 10a, 10 b. It should be noted that the formed segment 10 may be used in a variety of applications and industries, and is in no way limited to use in the automotive industry.

In fig. 2b, the position of the brazing wire 122 is further illustrated. As shown, the braze wire 122 is aligned relative to the laser beam 114. In some embodiments, the braze wire 122 is centrally aligned, meaning that: at some point, the longitudinal axis or wire path WP of the brazing wire 122 will intersect the longitudinal axis or radiation path RP of the laser beam 114 (see FIG. 2 a).

In fig. 2c, another situation is shown, wherein the brazing wire 122 is positioned off-center with respect to the laser beam 114. This means that: at any point, the wire path WP of the brazing wire 122 will not intersect the radiation path RP of the laser beam 114.

as explained above, it is important that the braze wire 122 be properly positioned relative to the laser beam 114. To ensure this, a laser brazing system 100 is provided. An embodiment of such a laser brazing system 100 is shown in fig. 3a and 3 b. In fact, both figures show the same embodiment of the laser brazing system 100, except that the position of the brazing wire 122 relative to the laser beam 114 is different.

the laser brazing system 100 includes a brazing tool 110. The brazing tool 110 has a laser 112 configured to emit a laser beam 114 along a radiation path RP. To this end, the soldering tool 110 may comprise suitable optics and drive circuitry (not shown). In addition, brazing system 100 has a brazing wire tool 120, the brazing wire tool 120 configured to direct a brazing wire 122 along wire path WP. In order for laser beam 114 to affect braze wire 122, wire path WP intersects laser beam 114 as described above. In an alternative embodiment, a box, indicated by reference numeral 112, encloses suitable optics, whereby the laser is provided remote from the optics 112 and connected to the optics 112 via an optical fiber.

Laser 112 is selected such that: when the brazing wire 122 is exposed to the laser beam 114, the brazing wire 122 will melt.

Brazing system 100 also includes a fixture 130. The clamp 130 is configured to be positioned relative to the braze wire 122 such that the braze wire 122 abuts the clamp 130, whereby the clamp 130 also blocks a portion of the emitted laser beam 114. When in this position, a measurement is performed. Brazing system 100 also has a detector 140, which detector 140 is configured to detect light passing over clamp 130, i.e., emitted light that is not blocked by clamp 130.

the general operating principle will now be explained with reference to fig. 3a and 3 b. In fig. 3a, the brazing wire 122 is centered with respect to the laser beam 114. When the clamp 130 is placed in contact with the brazing wire 122, an amount of light will reach the detector 140. On the other hand, as shown in FIG. 3b, when the braze wire 122 is disposed off-center with respect to the laser beam 114, a different amount of light will reach the detector 140. Thus, by analyzing the signal from the detector 140, it will be possible to determine whether the brazing wire 122 is properly positioned. Further, if the brazing wire 122 is not properly positioned, the degree of misalignment of the brazing wire 122 can also be determined. This method of determining the position of the brazing wire 122 preferably requires that the power density of the laser beam be symmetric about the radiation path RP.

More details of the laser brazing system 100 are shown in fig. 4. It can be seen that the clamp 130 is provided with two symmetrical portions 131a, 131 b. Each portion 131a, 131b has an alignment surface 132a, 132b and a blocking surface 134a, 134 b.

the two parts 131a, 131b are fixedly mounted on a support 135 driven by a drive unit 160. Control of the drive unit 160 is provided by a control unit 150, which will be described further below. The drive unit 160 (e.g., implemented in the form of a linear motor or other suitable component) is adapted to move the clamp 130 from an idle position (in which the clamp 130 does not affect the interaction between the laser beam 114 and the brazing wire 122) and at least a first measuring position. Optionally, the drive unit 160 is further configured to move the clamp 130 to the second measurement position, as will also be described further below.

Although it is taught that the drive unit 160 is coupled to the clamp 130, it should be appreciated that the drive unit 160 could equally be coupled to the laser brazing system 100 or any other related structure, so long as the drive unit 160 is capable of changing the relative position between the clamp 130 and the brazing wire 122.

Considering only the first portion 131a, in the first measuring position, the first alignment surface 132a is configured to be in contact with the brazing wire 122 such that the first alignment surface 132a forms a stop surface when the brazing wire 122 approaches the first portion 131a of the clamp 130 from the left. This is shown in particular in the enlarged detail of fig. 4. Thus, the first portion 131a acts on the brazing wire 122 in the same manner and direction as shown in fig. 3a and 3 b.

When the clamp 130 is positioned such that the first alignment surface 132a is in contact with the braze wire 122, the clamp 130 prevents exposure of the braze wire 122 to the laser beam 114. This means that: the alignment surface 132a must be configured so that proper shielding of the braze wire 122 is achieved. Further, the first blocking surface 134a (i.e., the blocking surface of the first portion 131a of the fixture 130) will block at least a first portion of the emitted laser beam 114. The exact amount of light blocked depends on the position of the braze wire 122 relative to the laser beam 114. To block light, the blocking surface 134a is tilted so that light impinging on the blocking surface 134a will be absorbed or reflected off the radiation path RP. To achieve the correct position of the stop surface 134a, the clamp 130 may be moved such that the alignment surface 132a is pressed against the braze wire 122. When the driving unit 160 experiences a certain resistance, the control unit 150 may generate a stop signal corresponding to the clamp 130 being prevented from further moving.

The portion of the light that is not reflected by blocking surface 134a will impinge upon detector 140. The detector 140 is arranged in the radiation path RP and is configured to transmit a signal S1 to the control unit 150 upon detection of incident light. Signal S1 includes information related to the amount of laser light detected when first barrier surface 134a blocks at least a first portion of emitted laser beam 114, e.g., signal S1 includes information related to the amount of light detected. From this information, the control unit 150 is configured to determine the position of the brazing wire 122 relative to the radiation path RP of the laser beam 114. This determination may be made in a number of different ways, some of which will be described below.

According to one example, the control unit 150 may access one or more pre-stored reference values representing an expected amount of detected light corresponding to a situation when the brazing wire 122 is centered with respect to the radiation path RP of the laser beam 114. In the case of only one reference value, the control unit 150 may be configured to compare the detected amount of light (i.e., the detected light value of the signal S1) with the reference value and determine the degree of matching of the values. For example, a resulting match value, which may be determined by dividing the amount of detected light by the reference value, may indicate whether the brazing wire 122 is located within or outside of the predetermined area. For example, a position of the brazing wire 122 of ± 20% with respect to a perfect centered alignment (perfect centered alignment) is acceptable, whereby the control unit 150 is configured to determine whether a ratio between the detected amount of light and the reference value is within or outside an interval corresponding to such ± 20% position control; if so, it is determined that the brazing wire 122 is properly positioned.

It is noted that the relationship between the measured amount of light and the position of the braze wire 122 is not necessarily linear.

According to another example, the control unit 150 may access two different reference values. These two values may represent a maximum value and a minimum value of the detected light, whereby the control unit 150 is configured to: if the detected amount of light is between the maximum reference value and the minimum reference value, it is determined that the brazing wire 122 is properly positioned.

According to yet another example, the laser brazing system 100 is configured to take advantage of the fact that: the fixture 130 also includes a second portion 131b having a second alignment surface 132b and a second stop surface 134 b. These surfaces 132b, 134b are symmetrically arranged with respect to the first alignment surface 132a and the first blocking surface 134a such that the clamp 130 can be located in a second measurement position in which the second alignment surface 132b is arranged in contact with the brazing wire 122 while the second blocking surface 134b blocks at least a portion of the laser beam 114. This position of the clamp 130 is shown in fig. 5.

The second alignment surface 132b faces a different direction than the first alignment surface 132 a; preferably, the first alignment surface 132a and the second alignment surface 132b face in opposite directions. Accordingly, the second blocking surface 134b faces a different direction than the first blocking surface 134 a; preferably, the first and second stop surfaces 134a and 134b face in opposite directions. In this context, the term "opposite" is used to describe two directions spaced 180 ° apart from the vertical. This means that: for a particular orientation of one surface 132a, 134a, the opposite orientation of the other surface 132b, 134b is preferably given by rotating the first direction by 180 ° along the vertical axis of rotation in the horizontal plane of rotation.

when the clamp 130 is arranged in the second measuring position, the control unit 150 is configured to receive the second signal S2 from the detector 140. The second signal S2 includes information related to the amount of laser light detected when the second blocking surface 134b blocks at least a second portion of the emitted laser beam 114. Similar to the first signal S1, the second signal S2 may include information related to the measured amount of light.

When receiving the second signal S2, the control unit 150 may process the second signal S2 in the same manner as the first signal S1, i.e., compare the second signal S2 with one or more reference values stored in advance.

However, when the control unit 150 accesses both signals S1 and S2, a comparison may be made between these signals S1, S2 in order to determine the position of the brazing wire 122 relative to the radiation path RP of the laser beam 114.

The relationship between each signal S1, S2 and the position of the braze wire 122 is shown in FIG. 6. Starting from the first signal S1, an initial value is obtained when the braze wire 122 is positioned offset in a negative direction. This value decreases as the offset decreases and reaches a neutral value when the braze wire 122 is centered. From here on, the measured amount of light decreases further as the amount of shift increases in the positive direction. The characteristics of the second signal S2 are opposite to those of the first signal S1; the maximum value is obtained at the maximum offset in the positive direction.

When both signals S1, S2 are accessed, the control unit 150 may be configured to determine the position of the brazing wire 122 relative to the laser beam 114 by comparing the two signals S1, S2. This comparison can be made, for example, by: the value of S1 is divided by the value of S2 to form a ratio. For settings requiring centering of the braze wire 122 in the laser beam 114, a result value close to 1 would indicate that the braze wire 122 is properly positioned, while a result value other than 1 would indicate that the braze wire 122 does not have its ideal position.

In the example shown in FIG. 6, for example, wire positions outside of the ideal working range of 0.2mm may be detected. The actual position is determined by calculating the ratio between the value of S1 and the value of S2. A ratio greater than 2 would indicate a wire position offset greater than about 0.2 mm. A ratio less than 0.5 would indicate a wire position offset less than about-0.2 mm. This ratio is expected to be close to 1 when the braze wire 122 is centered within the laser beam. Thus, if 0.5 ≦ RSi, S2 ≦ 2 (where RSi, S2 is the ratio between the current value of S1 and the current value of S2), it may be determined that the braze wire 122 is properly positioned.

By comparing the signals S1 and S2, a pre-stored reference value is not required. Furthermore, the laser brazing system 100 also becomes less sensitive to measurement errors, as the effect of such errors will be reduced.

Turning now to fig. 7, an example of a method 200 for monitoring the laser brazing system 100 will be explained. The method 200 comprises the following steps: activating 202 the laser brazing tool 110 to emit a laser beam 114 along a radiation path RP; and providing 202 a brazing wire 122 directed along a wire path WP intersecting laser beam 114. Thereafter, the method 200 further comprises: at least a first portion of the emitted laser beam 114 is blocked 206 by the fixture 130 and the emitted light of the laser beam across the fixture 130 is measured 208. For proper operation, the laser beam 114 should be emitted only when the brazing wire 122 is shielded by the clamp 130 to avoid undesired melting of the brazing wire 122.

the method 200 may continue from this point on with blocking 210 at least a second portion of the emitted laser beam 114 by the fixture 130 and subsequently detecting 212 the emitted light of the laser beam across the fixture 130. When blocked light has been detected for both positions of the fixture 130, the method 200 includes determining 214 a ratio based on the detection values from 208 and 212. Once the ratio is determined, the ratio is compared to a pre-stored reference value at 216. Thus, at 218, the position of the braze wire 122 is determined.

after 208, the method 200 may jump directly to 216 where the detected light is compared to a pre-stored reference value, followed by 218 where the position of the braze wire 122 is determined. It should be noted that if the detected light is used for comparison, the pre-stored reference value will be different than when the determined ratio is used for comparison.

The above-described laser brazing system 100 is a very effective system for monitoring a laser brazing process; by providing an automatic movement of the clamp 130, the determination of the position of the brazing wire can be performed very quickly before each initiated brazing process.

It is to be understood that the invention is not limited to the embodiments described above and shown in the drawings; rather, one of ordinary skill in the art appreciates that various modifications and changes can be made within the scope of the claims set forth below.