KR101321820B1 - Device and method for laser brazing - Google Patents

Abstract

Flux supply for supplying filler metal and flux for supplying filler metal to the joint of the workpiece to be bonded to magnesium homogeneous or dissimilar component connections using a laser heat source and to form a good quality joint through uniform temperature control. A laser irradiation part for irradiating a laser beam to the junction portion, a temperature measuring device for measuring the temperature of the junction part heated by the laser beam, and controlling the laser irradiation part according to the temperature value measured from the temperature measuring instrument to output the laser beam It provides a laser brazing apparatus and method comprising a controller for adjusting the.

Description

LASER BRAZING APPARATUS AND METHOD {DEVICE AND METHOD FOR LASER BRAZING}

The present invention relates to a laser brazing device. More particularly, the present invention relates to a laser brazing apparatus and method for joining a magnesium alloy using a laser heat source.

In general, magnesium alloy has a density of 1.74 g / cm 3, which is 1/3 of steel material, and is about 2/3 times lower than that of aluminum alloy. Due to these characteristics, applications are increasing in structures requiring weight reduction such as automobiles or portable products.

Manufacturing parts using magnesium alloys often requires combining two or more different materials of the accessory. For this purpose, bolt or rivet fastening, adhesion, etc. can be applied, but there are limitations in weight, cost, and performance. It is difficult to apply especially to the part which needs airtightness or watertightness.

Therefore, brazing technology is used when it is difficult to apply other fusion welding methods such as arc welding or heterojunction of the parts requiring airtightness or watertightness or arc welding due to the characteristics of the product.

Instead of melting and joining the base materials in order to bond the two separated base materials together, the brazing technique is by supplying and melting a brazing material (hereinafter referred to as a brazing filler metal) having a lower melting point than the base materials between the separated base materials. It is the process of completing the joining.

However, magnesium is highly oxidizable and has a low melting point, and since the filler metal for brazing is greatly limited by the performance of the joint and the shape of the joint, it is very difficult to join using the brazing technique.

As described above, the brazing of the magnesium alloy is difficult in the related art, and in particular, there is almost no brazing technique for the heterojunction between the magnesium alloy and other materials. Therefore, the development of brazing technology is urgently required to manufacture parts using magnesium alloy.

Accordingly, the present invention provides a laser brazing apparatus and a method capable of bonding magnesium homogeneous or dissimilar component connections using a laser heat source.

Also provided is a laser brazing apparatus and method for forming a good quality joint through uniform temperature control.

To this end, the apparatus is a flux supply part for supplying a filler material to the junction of the object to be joined and a flux supply part for supplying flux, a laser irradiation part for irradiating a laser beam to the junction, and measuring the temperature of the junction heated by the laser beam. And a controller for adjusting the output of the laser beam by controlling the laser irradiation unit according to the temperature measured by the temperature measurer.

The laser irradiation unit may include a laser oscillation unit for generating a laser beam and controlling its output, and a laser optical system for focusing the laser beam supplied from the laser oscillation unit to the junction portion.

The flux supply unit may have a structure for transporting the flux using an inert gas, and may have a structure for supplying the flux and the inert gas to the joint portion.

The temperature measuring device may have a structure for detecting the surface temperature of the junction.

The laser optical system may have a structure in which the laser beam is irradiated to the junction portion in a size of 2 to 20 mm in width and 2 to 50 mm in length.

At least one of the joined portions of the joined object may be a magnesium alloy.

The filler metal may be a magnesium alloy.

Meanwhile, the laser brazing method includes supplying flux and filler metal to a joint of a joined object, irradiating a laser beam to the joint, heating the flux, filler material, and a joint to braze the joint, and detecting the temperature of the joint to be brazed. The method may include controlling the output of the laser beam by comparing the temperature of the junction portion with a reference value.

The laser brazing method may further include supplying an inert gas to the junction to prevent oxidation of the junction.

In the brazing bonding step, the width of the laser beam irradiated to the bonding portion may be 2 to 20mm and the length may be 2 to 50mm.

At least one of the joined portions of the joined object may be a magnesium alloy.

The filler metal may be a magnesium alloy.

The range of the reference value for the output control of the laser beam may be 650 ~ 1000 ℃.

As described above, according to the present embodiment, it is possible to more easily perform brazing bonding between the magnesium alloy homogeneous or between the magnesium alloy and the double material using a laser.

In addition, by controlling the temperature of the brazing portion in an appropriate range, it is possible to obtain a uniform brazing joint.

Moreover, combustion by excessive heating of a filler metal or a to-be-joined part can be prevented.

In addition, uniform and excellent welding quality can be obtained regardless of the working environment or the skill of the operator.

1 is a schematic diagram showing a laser brazing apparatus according to the present embodiment.
2 and 3 are schematic diagrams showing the intensity distribution of the laser beam according to the present embodiment.
4 is a view showing the heating portion of the junction portion of the laser beam according to the present embodiment.
5 is a schematic flowchart illustrating a laser brazing process according to the present embodiment.
6 is a view showing a bonded portion brazed according to this embodiment.

Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings so that those skilled in the art can easily carry out the present invention. As those skilled in the art can easily understand, the embodiments described below may be modified in various forms without departing from the spirit and scope of the present invention. Wherever possible, the same or similar parts are denoted using the same reference numerals in the drawings.

All terms including technical and scientific terms used herein have the same meaning as commonly understood by those of ordinary skill in the art to which the present invention belongs. Predefined terms are further interpreted as having a meaning consistent with the relevant technical literature and the present disclosure, and are not to be construed as ideal or very formal meanings unless defined otherwise.

In the following description, a case of brazing bonding using a magnesium alloy as a brazing filler metal will be described as an example. However, the present invention is not limited thereto, and in the case of using a metal other than a magnesium alloy as the filler metal, it will be applicable to both.

1 shows a laser brazing apparatus according to the present embodiment.

As shown, the brazing device 100 is a filler material supply unit 10 for supplying the filler metal 12 to the junction (D) of the two to-be-joined material (P) for bonding, and supplying the flux 22 Flux supply unit 20 for, a laser irradiation unit 30 for irradiating a laser beam to the junction, a temperature measuring instrument 40 for measuring the temperature of the junction heated by the laser beam, measured from the temperature measuring instrument 40 And a controller 50 for controlling the laser irradiation part 30 according to the temperature value.

Therefore, the present apparatus can obtain a uniform brazing joint by controlling the temperature of the joint D in an appropriate range by brazing the joined object P and controlling the output of the laser beam by using a laser heat source. .

The filler metal supplier 10 is configured to continuously supply the filler metal 12 in the form of a wire. The brazing filler metal 12 means an insertion metal for joining the joined object P to each other. In the present embodiment, the filler metal may be a magnesium alloy. In addition, at least one of the junctions D of the joined object P may be a magnesium alloy.

In the present embodiment, the flux supply unit 20 is configured to continuously supply the flux 22 to the junction part D using an inert gas such as helium or argon as a carrier gas. Accordingly, while supplying flux continuously, inert gas such as helium or argon may be supplied to the junction D to prevent oxidation of the brazing junction.

The laser irradiation unit 30 includes a laser oscillation unit 32 for generating a laser beam and controlling an output, and a laser optical system 34 for focusing the laser beam supplied from the laser oscillation unit to the junction part D.

The laser oscillator 32 is controlled according to the output signal of the controller 50 to adjust the output value of the laser beam. The laser beam output from the laser oscillator 32 is focused through the laser optical system 34 and irradiated to the junction part D. As a result, a laser beam is absorbed and heated in the joined material, the filler metal, and the flux, and the flux and the filler metal are melted. The molten filler metal fills the joint D by the capillary pressure caused by the surface tension and the gap of the joint D, and the joined object P is brazed.

In general, in laser welding, in contrast to the use of a very small focused laser beam, it is advantageous in laser brazing to heat the junction to be brazed widely.

In the present embodiment, the laser irradiation unit 30 is based on the size of the laser beam is irradiated to the surface of the junction (D) of the object to be bonded (P), the size of the laser beam 2mm ~ 20mm, length 2mm ~ 50mm range Will be investigated. In this case, the width and the length are about two axial directions orthogonal to each other. For example, in the xy plane, the width means the y-axis size and the length means the x-axis size.

When the irradiation width of the laser beam is smaller than 2 mm, the laser beam is small and the heating of the bonding portion D is not sufficient, so that the wettability is insufficient. When the irradiation width of the laser beam exceeds 20mm, the heating area becomes excessive, so that deformation of the joined object P becomes severe after brazing bonding, and there is a problem that a higher laser power is used than necessary.

In addition, when the irradiation length of the laser beam is smaller than 2 mm, the heat holding time is too short, so that the reaction between the surface of the joined object P and the flux is insufficient, resulting in a low strength of the junction D. When the irradiation length of the laser beam is larger than 50 mm, deformation of the joined object P due to overheating becomes severe, and in the case of a low melting point filler such as magnesium, there is a problem of excessive evaporation.

In this embodiment, the irradiation form of the laser beam irradiated to the junction portion (D) forms a long oval or rectangular shape compared to the width.

To increase the size of the laser beam, as shown in FIG. 2, the laser optical system 34 has a structure showing an intensity distribution in the form of a top hat. In addition, the laser optical system 34 may use a conventional laser optical system as it is, and in this case, the size of the laser beam may be increased by adjusting the focal length of the laser optical system 34. 3 illustrates the intensity distribution of a laser beam when the focal length is changed in a laser optical system having a conventional structure.

FIG. 4 shows the heating mode of the junction portion D of the laser beam by the laser optical system 34 according to the present embodiment. The laser optical system 34 reduced the focal length by 30 mm using the optical system of the conventional welding diode laser and irradiated the surface of the junction D with the laser beam. In this case, as shown in Figure 4, the area heated by more than about 700 ℃ by a laser beam was an oval of about 10mm in width and 16mm in length, and included both flux and filler material.

On the other hand, the controller 50 controls the laser irradiation unit 30 according to the temperature of the junction (D) detected through the temperature measuring device (40). The laser irradiation unit 30 adjusts the laser beam output according to the output signal of the controller 50.

In the present embodiment, the temperature measuring device 40 is a non-contact structure, spaced apart from the junction (D) has a structure for detecting the surface temperature of the junction (D). For example, the temperature measuring device 40 may be an infrared type temperature measuring device 40.

The controller 50 incorporates data having a suitable temperature range for the junction D as a reference value, and a calculation formula for comparing and calculating the temperature value detected by the temperature measuring device 40 with the reference value.

Accordingly, the controller 50 controls the laser irradiation unit 30 to adjust the output of the laser beam when the actual temperature of the junction D detected by the temperature measuring device 40 is out of the reference value.

The reference value ranges from 650 to 1000 ° C. when brazing the magnesium alloy.

Magnesium alloy filler metal has an evaporation temperature of 1107 ° C, and when heated to a temperature near this, combustion proceeds explosively. If the filler metal or the junction (D) surface is excessively heated, the filler metal burns. Accordingly, the reference value may be set in the range of 650 ~ 1000 ℃. This is because when the temperature of the junction D is less than 650 ° C., the filler metal is insufficiently melted and the wettability is insufficient on the surface of the junction D even if it is partially melted. This is because the oxidation proceeds explosively by reaction.

Hereinafter, the brazing bonding process will be described with reference to FIG. 5.

For laser brazing bonding, flux and filler material are fed to the bonding portion D of the joined object P. FIG. The laser oscillator 32 performs an overall control operation related to the generation and supply of the laser beam to irradiate the laser beam to the junction portion D through the laser optical system 34. (S100 to S200)

As a result, a laser beam is absorbed and heated in the joined material, the filler metal, and the flux, and the flux and the filler metal are melted. The molten filler metal fills the joint D by the capillary pressure caused by the surface tension and the gap of the joint D, and the joined material is brazed.

In this process, the surface temperature of the junction D is detected in real time through the temperature measuring device 40. The temperature value detected through the temperature measuring device 40 is applied to the controller 50. The controller 50 checks whether or not the junction D temperature deviates from the reference value by comparing and calculating the temperature value of the actually measured junction D with a reference value set as a temperature value for the desired brazing junction. S300 ~ S400)

When the temperature of the junction D is out of the reference value, the controller 50 outputs a control signal to the laser oscillator 32 to control the laser oscillator 32. The laser oscillator 32 adjusts the output value of the laser beam according to the signal of the controller 50. (S500)

For example, when the temperature of the junction D falls below the reference value, the controller 50 increases the output of the laser beam output from the laser oscillator 32. The laser beam of stronger output is irradiated to the junction part D, and the heating temperature of the junction part D is raised.

6 shows a brazed joint D according to the embodiment described above.

In FIG. 6, magnesium alloy was used as the filler metal, and the junction (D) temperature was maintained within 800 ° C. The temperature measurement used a non-contact infrared temperature measuring method.

As shown, it can be seen that uniform and high quality brazing can be achieved by heating the junction D at an optimal temperature condition.

While the illustrative embodiments of the present invention have been shown and described, various modifications and alternative embodiments may be made by those skilled in the art. Such variations and other embodiments will be considered and included in the appended claims, all without departing from the true spirit and scope of the invention.

10: filler material supply unit 12: filler material
20: flux supply part 22: flux
30: laser irradiation unit 32: laser oscillation unit
34: laser optical system 40: temperature measuring instrument
50:

Claims (11)

A laser brazing device comprising: a filler material supply unit for supplying filler metal to a joint of a joined object, a flux supply unit for supplying flux, and a laser irradiation unit for irradiating a laser beam to the joint, so that the magnesium alloy can be bonded.
A temperature measuring device for measuring the surface temperature of the junction portion heated by the laser beam, and further comprising a controller for controlling the output of the laser beam by controlling the laser irradiation unit in accordance with the temperature value measured from the temperature measuring instrument,
At least one of the joined portions of the joined object or the filler metal is a magnesium alloy,
The laser irradiation unit includes a laser oscillation unit for generating a laser beam and controlling its output, and a laser optical system for focusing the laser beam supplied from the laser oscillation unit to the junction portion,
The flux supply unit supplies the flux and the inert gas to the junction using an inert gas as a flux carrier gas,
The controller includes a calculation formula for comparing and calculating a reference value, which is an appropriate temperature range for the junction, and a temperature value of the junction detected from the temperature measuring instrument, and adjusts the output of the laser beam so that the reference value is in the range of 650 to 1000 ° C. , The laser optical system is a laser brazing device for irradiating the junction portion with a laser beam size of 2 to 20mm in width, 2 to 50mm in length. delete delete delete delete delete What is claimed is: 1. A laser brazing method comprising the steps of: supplying flux and filler metal to a joint of a workpiece to be bonded to a magnesium alloy; ,
Detecting the surface temperature of the junction to be brazed, controlling the output of the laser beam by comparing the temperature of the junction to a reference value,
Supplying an inert gas to flux the junction to prevent oxidation of the junction, at least one of the junction of the joined or the filler metal is a magnesium alloy, the range of the reference value for the output control of the laser beam is 650 ~ 1000 ℃, the laser beam irradiated to the bonding portion in the brazing bonding step is a width of 2 ~ 20mm and a length of 2 ~ 50mm laser brazing method.
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