This invention relates to a method for manufacturing metal strip, particularly relates to a method for manufacturing metal strip which can detect welding penetration depth by spectrometer to correct welding penetration depth in real time.
In order to prevent the active components from damage caused by huge current surge, electric resistance element is usually installed in the power control module of precise electronic products for voltage sensing and stabilizing. And those skilled in the art usually manufacture heterogeneous metal strip by high energy electron beam welding, because high energy electron beam welding has some advantages, like high aspect ratio of welding fusion zone and small heat-affected zone, and the heterogeneous metal strip can be cut equidistantly to form low resistance elements.
However, electron beam welding has to be performed in vacuum chamber and the equipment cost is high. In addition, electron beam welding is difficult to detect welding penetration depth of weld pass in real time for adjusting welding parameters, and welding quality only can be detected by metallurgical analysis of weld pass when the welding is finished, so product yield improvement is not easy. Furthermore, the metal strip after electron beam welding must be trimmed by laser cutting or machine grinding for correct resistor is main issue for those skilled in the art.
The primary object of the present invention is to provide a method for manufacturing metal strip, wherein a weld pass is formed by laser welding metal strip, and a spectrometer is adapted to detect the spectrum of reflected light which is reflected from the weld pass. So welding penetration depth of the weld pass can be detected and corrected in real time for decreasing welding defective proportion efficiently.
A method for manufacturing metal strip comprises abutting at least two metal strips, wherein a abutment interface is formed between the metal strips; welding the metal strips by a laser light, wherein the laser light is applied to the abutment interface and welds the metal strips along the abutment interface to form a weld pass with a welding penetration depth between the metal strips, and a reflected light is reflected from the weld pass; and receiving the reflected light by a spectrometer, wherein the spectrometer determines the welding penetration depth according to the reflected light spectrum, and a welding parameter is adjusted selectively according to the welding penetration depth for correcting the welding penetration depth in real time.
The present invention uses the laser light to weld those metal strips, so the weld pass has some advantages, like small heat-affected zone, higher aspect ratio of welding fusion zone and smooth surface. And the present invention uses the spectrometer to detect the spectrum of the reflected light for determining the welding penetration depth, and the welding parameter can be selectively adjusted in real time to correct the welding penetration depth when the welding penetration depth is out of the specification. Therefore, the welding penetration depth will not be out of the specification continuously.
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Before step 11, a grinder (not shown in drawing) is preferably adapted to grind the surface and lateral side of the metal strips M for removing burr and oxide. And grinding the surface of the metal strips M can make the thickness of the metal strips M being consistent, and grinding the later side of the metal strips M can make the width of the metal strips M being conformed to the specification.
The metal strips M can be made of same or different materials. The metal strips M involve a first metal strip M1, a second metal strip M2 and a third metal strip M3 in this embodiment, wherein the first metal strip M1 is located between the second metal strip M2 and the third metal strip M3. The first metal strip M1 can be made of copper (Cu) alloy, manganese (Mn) alloy, molybdenum (Mo) alloy, nickel (Ni) alloy, chromium (Cr) alloy or tin (Sn) alloy, and the second metal strip M2 and the third metal strip M3 can be made of copper (Cu), aluminum (Al) or silver (Ag). In this embodiment, the first metal strip M1 is made of manganese-copper (Mn—Cu) alloy, and the second metal strip M2 and the third metal strip M3 are made of copper (Cu).
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The spectrometer 200 can detect the welding penetration depth of the weld pass W according to the wavelength variation in the spectrum of the reflected light L2. The spectrometer 200 will feedback a signal to the feeding platform 100 when the welding penetration depth of the weld pass W does not conform to the specification, and the feeding platform 100 can selectively adjust a welding parameter based on the welding penetration depth of the weld pass W to correct the welding penetration depth of the weld pass W in real time for specification conformance. Preferably, the scan speed of the spectrometer 200 is about 0.2 ms, so the spectrometer 200 can feedback the signal to the feeding platform 100 for adjusting the welding parameter in real time. And the weld parameter is power of the laser light L1 or the feeding speed of the metal strips M which is same with the speed of the metal strips M passing from below the laser welding head 160. Based on the feedback signal from the spectrometer 200, the power of the laser light L1 is adjustable between 1000 and 2000 W and the feeding speed of the metal strips M is adjustable between 1000 and 2000 mm/min for manufacturing the weld pass W with the welding penetration depth conforming to the specification.
The spectrometer 200 will feedback the signal to the feeding platform 100 to improve the power of the laser light L1 or slow down the feeding speed of the metal strips M when the welding penetration depth of the weld pass W is below the specification, hence the welding penetration depth of the weld pass W can be increased immediately. On the contrary, the spectrometer 200 will feedback the signal to the feeding platform 100 to decrease the power of the laser light L1 or enhance the feeding speed of the metal strips M when the welding penetration depth of the weld pass W is higher than the specification, so the welding penetration depth of the weld pass W can be decreased immediately.
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Preferably, the welded metal strip will be transported to another grinder (not shown in drawing) after step 13, the grinder is used to grind and smooth the welded metal strip for follow-up furling.
The present invention can adjust the welding parameter of the feeding platform 100 and correct the welding penetration depth of the weld pass W in real time by the spectrometer 200 which can detect the welding penetration depth of the weld pass W. Hence, the present invention can detect the welding quality during welding, and the welding quality obtained according to metallurgical analysis of the weld pass W after welding whole roll of metal strip is not necessary. The welding quality of the welded metal strip manufactured by the present invention is excellent, and the welded metal strip is adapted to produce the resistance element with specific resistivity by cutting equidistantly, wherein the resistance element with specific resistivity can be applied to power control module of precise electronic products.
While this invention has been particularly illustrated and described in detail with respect to the preferred embodiments thereof, it will be clearly understood by those skilled in the art that is not limited to the specific features shown and described and various modified and changed in form and details may be made without separation from the spirit and scope of this invention.