TPT July 2021

T E CHNOLOG Y

Latest developments of the efficient double- car t flying tube saw from Dalian Field

DALIAN Field (FD Machinery) has celebrated the growing success of its double-cart flying saw concept, which was first released in 2015. The sawing application can be integrated into an existing production line or as a brand new production line. More and more welded pipe enterprises have been choosing to purchase the double-cart flying saw, because of its excellent improvement in performance. It helps to boost production speed and minimum sizing length and it is these two characteristics of the double-cart in flying saw in particular that have increased its popularity. An increase in production speed was the original intention of the research carried out on double-cart flying saws. There were two bottle neck problems that made the speed increasing difficult: strip joint and pipe cutting. Although the length of the strip keeps increasing with the emergence of automatic material preparation equipment, the strip joint problem has now been resolved. However, it is still difficult to speed up due to cutting time being limited. At 120m/min speed and 6m in length, the cutting time is only 0.6 to 0.8 seconds, which is almost punching. This is not sustainable for a saw blade and the life of the saw blade is greatly

reduced. Many production lines are designed to work at high speed, but the high cost of saw blades and the time required for blades replacement will usually offset all of the benefits brought by high speed and can even result in negative value. If the double-cart flying saw is in the above working conditions, the actual pipe length of each saw will be 12m and the cutting time is even more than two seconds, which is two to four times that of the single saw. It can not only increase the speed, but also improve the life of the saw blade. There are two ways to increase the efficiency: one is to improve the highest speed setting, mainly for small specification mills; the other is to improve the speed of intermediate specifications, mainly for mills with a wide specification range. The highest speed of this kind of mill is run on small specifications, but these account for a small proportion of production. Increasing the speed has little contribution to production, and the flying saw walking motor has to be increased in power a lot. Most of the time it is not cost effective. Therefore, Dalian Field suggests improving the speed of the intermediate specifications as this

has a significant effect on improving production capacity. If the speed of large specifications is improved, the HF welder and power supply has to be increased. The power investment and the cost of mills are both higher, therefore, before making the choice of mill speed. It is important to understand the characteristics of mills and market demands to so that the user can avoid making a bad decision. The speed characteristic of the minimum cut-to-length is an important characteristic of the fly saw. For example, the speed is 120m/min for a pipe length of 6m. When the tube length is less than 6m the production speed has to be reduced; usually when the tube length is less than 4m, the cutting length has to be multiples of 4m, which wastes manpower, production time and materials. The minimum cut-to-length of the double saw can be smaller, because the speed on 4m lengths for the double cart saw is equivalent to the 6m speed of the single saw. If the mill speed is reduced, 3m or even a 2m pipe can be produced.

Dalian Field www.fdmachinery.com

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JULY 2021