The author has been working in the cabo flexível industry for over 18 years and has encountered numerous customers who have encountered problems using cabo flexível. Some have chosen the wrong outer sheath material due to neglecting the usage environment, some have chosen the wrong grade of drag chain cable due to neglecting the minimum bending radius of the cabo de corrente de arrasto, and some have chosen cables that are only resistant to bending and cannot withstand twisting due to the actual cable movement conditions.
In recent years, with the rapid development of Industry 4.0, most engineers engaged in industrial automation have accumulated a lot of experience in the selection of cabo de alta flexibilidade. The above-mentioned issues that are easily overlooked rarely occur, except for a seemingly unimportant small problem that has not been taken seriously. Occasionally, the cause of the problem cannot be found, which is the stroke of the drag chain cable.
Why did this problem occur? Because most flexible cable manufacturers themselves do not pay attention to the impact of the travel of drag chain cables on their lifespan, and do not provide customers with correct selection guidance. Most flexible cable manufacturers conduct drag chain cable life tests in their laboratories under very short drag chain travel, and the resulting drag chain cable has a long service life.
A practical case sharing
Last year, the author also encountered the same problem when a customer purchased unshielded 4×1.5 flexible cables from the author’s company and used them on a large vehicle fully automatic cleaning equipment. Due to the slow movement speed and large bending radius of the drag chain on the device, reaching 600mm, the frequency of daily drag chain movement is also very low, approximately less than 500 back and forth movements per day. At that time, the customer believed that this device did not have high performance requirements for cabos flexíveis, so they chose the standard flexible cable model. After more than 2 months of use, the cables in the drag chain have become severely twisted and deformed. When the customer reported this issue to the author, the author inquired about the operating conditions of the customer’s cable and discovered that the customer’s equipment drag chain had a travel distance of 45 meters.
The conclusion drawn from the author’s on-site survey and analysis of cable samples with problems is that standard flexible cables used in drag chains with a travel of 45 meters, even if the drag chain moves slowly and has a large bending radius, greatly reduce the lifespan of the drag chain cable. A 45 meter travel drag chain must use a cabo de corrente de arrasto de longa distância.
Based on the above case analysis, we can draw some experiences and conclusions：
Long distance drag chain cable, three major points of life loss
1. Continuous tensile stress caused by the self weight of cabo altamente flexível
The longer the drag chain, the greater the weight of the entire cable. During operation, the lower section of the cable will fall and pull the internal copper wire throughout the entire process.
Short distance travel hardly feels any pulling force; The ultra long vertical and horizontal drag chain keeps the cable in a tight state, and the fine copper wire is subjected to long-term tension, greatly accelerating the fatigue fracture speed.
Correct selection plan: Choose a drag chain cable with built-in aramid tensile yarn, reserve slack allowance for wiring, and secure both ends to relieve stress.
2. At the same operating speed, the number of bending cycles increases sharply
For example, the equipment drag chain reciprocates 20 times per minute
● Short travel of 2 meters: short single bending distance, small cable deformation amplitude;
● Long journey of 10 meters: The entire section of the cable is significantly bent, sliding and rubbing, and the wear of the sheath and fatigue loss of the copper wire are more than 10 times higher in the same time.
The same cable can last for 2 years with a 2-meter travel, but a 10 meter long travel may malfunction within six months.
3. Friction distance between cables increases
Multiple wires inside the drag chain are adjacent to each other and rub against each other every time they move back and forth.
Short travel friction distance and slow wear of the outer skin; Continuous friction throughout the long distance can easily cause the sheath to become thin and crack, leading to a short circuit when water or oil enters.
In summary
Ao selecionar cabos altamente flexíveis, in addition to factors such as the cable’s usage environment, the speed of the drag chain movement, and the bending radius, the travel distance of the drag chain cannot be ignored. If necessary, long distance flexible cables should be selected.