Brazing, soldering and welding specialist Dr Shin from South Korea: The Managing Director of Korean machinery equipment supplier SK Brazing presented several improved products for the manufacturing of tanks and collectors at the Intersolar North America in San Francisco in July 2010.
Photo: Bärbel Epp
“We do not just want to sell machines, but we also intend to optimize processes for our customers,” Dr Shin explains. So he developed a pipe-end forming machine, which creates a ring about 3 to 5mm before the end of a pipe. Such a technique possesses several advantages: “You can reduce the loading time and position the pipes very accurately in the manifold, even with an automated array brazing machine,” Dr Shin says. The ring near the end of each pipe determines the depth up to which this pipe can enter the manifold. According to the Managing Director, the precise brazing along the ring allows a manufacturer to use less brazing alloy and, at the same time, reinforce the brazing joint.
Regarding the manifold, the engineer recommends drilling from the outside instead of punching holes from the inside of the pipe. “To have a good brazing result, you have to make sure that your holes are perfectly round, positioned at precise locations and do not have a tear burr,” explains Dr Shin. “The thin walls of a tear burr resulting from the punching process can create pinholes and very small leaks during the brazing process.“ Nevertheless, his company offers machines for both drilling and punching and according to manufacturers´ information they both have about the same speed of around 2 sec per hole.
Checking along two axes: SK Brazing's newly developed vision sensor unit checks the welding joint before the TIG torch welding unit starts its job.
Photo: SK Brazing
The second innovation presented at the Intersolar concerns the automated production line for water tanks. SK Brazing developed a vision sensor for the line's welding machine, which will support automated welding of the tank's caps. “Our vision sensing system is more sophisticated than methods such as mechanical or laser beam scanner currently used in the industry,” explains Dr Shin. The vision sensing system checks both X- and Z-axis with servo motors, and it will give accurate control for the Tungsten Inert Gas (TIG) welding process. According to SK Brazing, the memory unit of the sensors will make it easy to change to different tank models. And how is such a vision unit protected from the high welding temperatures? The vision sensor checks the size of the welding before the welding gun comes down to the tank, which means that the sensor unit will have completed its task before the start of the welding process. It also means that the process requires two turns around the cap of the tank. Dr Shin emphasizes that the total time spent for the vision check and the welding does not differ much from the current scanning and welding processes: “We can make a faster welding, because we can get very accurate welding position through visioning”.
SK Brazing was formed in 1987 as a division of EAC, a US-Korean joint-venture. Six years later, Dr Shin bought the division and established an independent company, which he has run ever since. Currently, SK Brazing has around 30 employees and services solar thermal clients all around the world, for example in the US, Australia, Greece, South Korea, Spain, China, India and, as the latest addition, even in Azerbaijan. The utility there is called Azenco and will start producing collector panels soon.