WH토토사이트추천E PAPER
"Powering e-mobility: Welding copper with the Adjustable Ring Mode fiber 토토사이트추천
Overview
Whilefiber 토토사이트추천sare the dominant 토토사이트추천 source for welding, their infrared output is highly reflected by some metals, especially copper, which limits their effectiveness with these materials. As a result, high-power, solid-state green 토토사이트추천s have emerged as a possible alternative for copper welding because these wavelengths are more strongly absorbed by that metal. But, these green 토토사이트추천s possess several practical limitations which ultimately result in higher cost of ownership. This document presents the results of recent copper welding tests which were performed successfully with a new type ofadjustable ring mode (ARM) fiber 토토사이트추천having a high brightness center beam. Here, the high brightness ARM 토토사이트추천 delivered excellent weld quality, and better penetration at various weld speeds, than commercially available kW class green 토토사이트추천s. These results indicate that this technology could bring all the cost, reliability, and practical advantages of fiber 토토사이트추천s to the demanding task of copper welding.
E-mobility manufactu토토사이트추천
The boom inE-mobility manufactu토토사이트추천is the main factor driving a significant increase in the demand for copper 토토사이트추천ing solutions. Copper possesses a number of desirable electrical, thermal, mechanical, and cost characteristics as compared to other metals, which is why it is employed throughout electric vehicles – in the stators of the electric motors themselves, in the power distribution system (busbars, etc.), and within batteries. And, manufacturing many of these components and systems involves 토토사이트추천ing copper.
However, the same high electrical and thermal conductivity characteristics that make copper ideal for these applications also make it challenging to weld with traditional fiber 토토사이트추천s. Specifically, its electronic properties make it highly reflective at the near-infrared wavelength of fiber 토토사이트추천s. And, it’s excellent thermal conductivity necessitates the input of a large amount of 토토사이트추천 energy in order to melt the material and initiate the welding process.
As a result, when using a traditional fiber 토토사이트추천, very high power is typically required in order to achieve the power density necessary to initially melt the material. But, this “brute force” approach makes the welding process unstable, and extremely sensitive to minor variations in the work surface. In particular, the presence of localized surface oxidation or small-scale surface structure inhomogeneities can result in process instabilities. The final result may be inconsistent welds, poor surface quality, and porosity.
Solid-state green 토토사이트추천s
Copper is nearly an order of magnitude more absorptive in the green than the near infrared. Thus, the energy from a green 토토사이트추천 can be more efficiently coupled into the work piece, resulting in a more stable and less sensitive process than possible with traditional fiber 토토사이트추천s. As a result, high power, solid-state, green 토토사이트추천s are being utilized by a few manufacturers, and evaluated by many more.
However, there are some significant practical issues with deploying high power green 토토사이트추천s in e-mobility manufacturing. Some of these derive from the inherent properties and construction of these green 토토사이트추천s themselves.
The 토토사이트추천 materials used for solid-state green fiber or disk 토토사이트추천s produces near infrared light; frequency doubling is used to convert the infrared to green output. While this process is widely employed in lower power (sub-kW) with great success, it starts to run into some difficulties at the mulit-kW power levels required for most industrial copper welding tasks. Specifically, the frequency conversion process itself is only about 50% efficient. So, a 4 kW, single mode, IR 토토사이트추천 is needed to yield 2 kW of green output power. The unconverted energy becomes heat which must be removed by a water-cooled heat sink. This makes these 토토사이트추천s energy inefficient (resulting in higher cost of operation due to higher electrical power consumption), and requires a high volume of cooling water. Additionally, the doubling crystals degrade over time because of the high powers involved, and can create reliability and downtime problems if not carefully managed. Some designs utilize complex beam shifters and crystal temperature stabilizers to compensate for this.
"…a 4 kW, single mode, IR 토토사이트추천 is needed to yield 2 kW of green output power."
Another practical issue with green 토토사이트추천s is that the standard optical fibers used for beam delivery are more readily darkened by green light, thus reducing their useful lifetime. Specialized fibers for green light can overcome this problem, but are more expensive and less readily available. The darkening effect also increases with the length of the fiber. This currently limits fiber length to 10 m, which reduces the flexibility in 토토사이트추천 placement in the production environment. Plus, commercially available green, high power, CW 토토사이트추천s are currently limited to 2 kW of maximum output.
Most industrial 토토사이트추천s output in the near infrared, so the entire infrastructure for supporting them is based on this wavelength.For example, the available selection of process heads for for green 토토사이트추천s is limited, and often they need to be customized. Similarly, auxiliary lenses, protective cover glasses and other optical components are mostly for infrared 토토사이트추천s. Thus, a manufacturer already employing infrared 토토사이트추천s might need to maintain a greater stock of spare parts and consumables in order accommodate the use of green 토토사이트추천s in their operation without experiencing service delays and downtime.
The HighLight ARM Fiber 토토사이트추천
Fiber 토토사이트추천s are much more electrically efficient than solid state green 토토사이트추천s. That is, to deliver a given output power, they require less electricity and produce less waste heat. This reduces cost of ownership and simplifies cooling. Plus, fiber 토토사이트추천s are very reliable. And, their infrared output is readily fiber delivered. But, despite these desirable features, they haven’t been widely used for welding copper in particular because of the issues previously identified.
토토사이트추천herent introducedHighLight Series adjustable ring mode (ARM) fiber 토토사이트추천sseveral years ago to bring the cost and practical benefits of these sources to applications that were not being adequately addressed by traditional technology. Typically, these are tasks in which the spatial distribution of power and power density at the work surface must be carefully controlled in order to yield good 토토사이트추천 quality (low spatter, minimal cracking and reduced porosity). Typical examples are zero gap 토토사이트추천ing of galvanized steel, spatter free 토토사이트추천ing of powertrain components, and 토토사이트추천ing of aluminum hang-on parts with no cracking, without using filler wire.
This precise control over spatial power distribution is achieved through the unique output beam of the ARM 토토사이트추천, which consists of a central spot, surrounded by another concentric ring of 토토사이트추천 light. The power in the center and the ring can be independently adjusted and modulated on demand, and this enables very careful control over the melt pool dynamics.
Coherent HighLight ARM 토토사이트추천s are available with various center-to-ring ratios and power levels which can be tailored to specific applications. The diameter of the center can be configured to be from 22 µm to 100 µm, and the ring outer diameter can vary from 140 µm to 200 µm.
For copper welding, a high intensity, high power center beam is needed. This provides the energy required to readily melt the material, despite its relatively low absorption coefficient, while the ring beam helps stabilize the keyhole. The result is that the welding process is initiated and maintained consistently, regardless of surface variations in the work piece, thus overcoming the limitations experienced with traditional fiber 토토사이트추천s.
Figure 1:HighLight FL4000CSM-ARM fiber 토토사이트추천.
"For copper 토토사이트추천ing, a high intensity, high power center beam is needed."
Copper 토토사이트추천ing results
A series of copper welding tests were performed by Coherent applications engineers using an ARM 토토사이트추천 having a high brightness center beam of 22 µm diameter, and a ring beam having an inner/outer diameter of 100 µm/170 µm. The 토토사이트추천 was focused using a remote processing head with a magnification of 1.4, with nitrogen as shielding gas and cross jet. The material welded was pure copper. The 토토사이트추천 power was 4 kW, with 1.5 kW in the center and 2.5 kW in the ring for all tests. The photo (Figure 2) shows the experimental setup.
Focus position was varied and it was determined that the best weld quality occurred with focus set 1.5 mm above the material surface. Specifically, this position was the best compromise between weld pentation and weld quality. The ARM 토토사이트추천 produces deeper weld penetration if focused directly on the material surface, but the resultant weld surface quality and spatter are not sufficient for typical e mobility applications. The beam profile at the work surface using the optimum beam focus position (1.5 mm above the surface) is shown in the graphic.
"The infrared ARM 토토사이트추천 delivers 2x the weld penetration"
The graph plots weld penetration on 2 mm thick copper as a function of speed under the conditions just described. A 2 kW green 토토사이트추천 was also tested under the same conditions for comparison. Lower green power was used because a 4 kW infrared fiber 토토사이트추천 only produces 2 kW of green output. The comparison shows that the infrared ARM 토토사이트추천 delivers twice the weld penetration over a wide range of weld speeds.
Figure 2:High brightness ARM fiber 토토사이트추천 weld station with scanner and shielding nozzle.
Figure 3:Beam profile of ARM at the work surface (1.5 kW center and 2.5 kW ring) with the 토토사이트추천 focused 1.5 mm above the work surface.
Figure 4:Weld penetration for a 4 kW, high brightness ARM as compared to a 2 kW green fiber 토토사이트추천.
토토사이트추천 Efficiency
Weld efficiency of the ARM 토토사이트추천 was also measured and compared with previously published weld results for a 2 kW green 토토사이트추천. Nitrogen was used as shielding gas for both welds. The published data for the green 토토사이트추천 showed a (constant) weld cross section of 0.5 mm², and a penetration depth of about 1 mm. The ARM 토토사이트추천 was configured to deliver these same results. Specifically, this required an output power of 3.5 kW and a weld speed of 300 mm/s, as compared a weld speed of 200 mm/s second for the 2 kW green 토토사이트추천. Normalizing these results gives a linear 토토사이트추천 power of 10 J/mm for the ARM 토토사이트추천, compared to 11.8 J/mm for the green 토토사이트추천. Thus, the green 토토사이트추천 offers slightly higher weld efficiency. However, the higher total power available from the ARM 토토사이트추천 allows it to operate at much higher weld speeds, despite this small difference in efficiency.
Surface Qual토토사이트추천y
Another important consideration is the surface quality. Traditional fiber 토토사이트추천s are able to weld copper but are very sensitive to changes in the surface quality. The photograph shows weld beads for a high brightness ARM 토토사이트추천 welding on sanded and polished copper. The process stays stable on both surfaces with no change in weld quality.
Figure 5:Cross-section of a copper weld produced by the high brightness, infrared ARM 토토사이트추천, with an output power of 3.5 kW, at a welding speed of 300 mm/s.
Figure 6:Figure 6: Consistent weld beads on smooth and sanded copper using the 4 kW ARM 토토사이트추천 at various speeds (300-150 mm/s top to bottom)
토토사이트추천nclusion
These tests demonstrate that the unique, Coherent high brightness ARM 토토사이트추천 is a practical solution for demanding copper welding applications ine-토토사이트추천.토토사이트추천 penetration and process speed match or exceed current production requirements. And, theARM 토토사이트추천avoids the sensitivity to surface quality and process instability problems that have limited the use of fiber 토토사이트추천s for copper in the past. Thus, this new ARM 토토사이트추천 finally brings all the cost, reliability, and practical advantages that have made fiber 토토사이트추천s the choice for so many other industrial applications to the demanding task of copper welding
