Stainless steel pipe fittings drawing processing, usually found near one end of the clip, some small diameter stainless steel pipe fittings, its wall thickness size and drawing pipe billet is the same as the former, is only the reducing pipe didn’t decrease wall deformation, cause empty pull effect. If the empty pull segment is relatively short, as long as it is cut off at the cutting head, the yield, quality and use of the stainless steel pipe will not have much impact. However, if the empty segment is longer or too long, when the stainless steel pipe is produced, it will cause a short ruler to be scrapped. If you don’t pay attention when cutting the stainless steel pipe or inspection, you will not be able to use it properly and even have an accident.
There are five main reasons for the short length of the stainless steel. First of all, the core stick forward is not timely. In general, the operation process of the fixed short core bar drawing is to remove the core rod from the first place to the back limit position, and the short core rod is pulled out from the die hole. To lubricate the inner wall of the head and lubricate the inner wall from the back end. Core rod to go forward, to promote the stainless steel pipe billet clamp side wear out from the die hole, because is affected by the holder, at this time of the mandrel can not progress to the specified location, mandrel will continue to keep the forward thrust. When the clip head is worn out of the die hole, it is clamped by the pull of the car, and then pulled out from the die hole before pulling out the car. But in the actual production, drawing medium and small sizes of stainless steel pipe fittings, pipe set on the mandrel, after operation are the clip from the die hole, since the core rod to move forward to promote core rod into the people die. During the operation, sometimes the mandrel has not started to move forward, and the clamping of the die hole will be clamped forward by the car tongs, resulting in a longer empty segment.
The second reason is the core bar. If mandrel position adjustment is not appropriate, too, at the beginning of the drawing mandrel is not easy to smoothly into the person die, even in the entire process of drawing, into not to die, there will be a period of the sky, even also can have the entire length of stainless steel pipe fittings all empty cases.
The third reason is that the mandrel is not fixed. In fixed short mandrel drawing, because the core rod and pipe billet surface will be within the lubricating oil, to depend entirely on the pipe wall friction with mandrel brought its people die is more difficult, the back-end must have a thrust. If the core stick is not fixed, the core rod has not entered the manhole and the thrust disappears. It can also be extruded, resulting in the formation of the air pull.
The fourth reason is that the gap between the core and the pipe is too large. When swimming core head drawing, if the core gap between head and the pipe is too big, especially when small drawing specification stainless steel pipe fittings, in drawing at first, the core head is not stable in the pipe billet, is very difficult to enter the deformation area, leading to empty, pull.
The fifth is that the stainless steel pipe billet is not stopped. When the head of the moving core is pulled out of the small size of the thin wall pipe, the core head shall be mounted on the surface of the stainless steel pipe at the back of the core, and a pit shall be punched in the outside, so that the core head should not be moved backward. If it is not in the pipe, the core is not easy to enter the deformation zone, thus forming a long empty segment.
The main measures to reduce the air segment of the stainless steel pipes are 3 points. First, it is the standard operation procedure. When the stainless steel pipe is worn out of the die hole, the core bar is pushed to the die hole and then pulled and pulled. When using the hydraulic cylinder to control the mandrel, do not step back in the whole drawing process. When the pedal method is controlled, the core rod should not loosen the pedal before entering the die hole.
The second is to adjust the position of stainless steel mandrel, not too close, but not too forward. When using a moving core, the gap between the large cylinder and the stainless steel pipe is not too large, and the clearance should be reduced as far as possible without affecting the core head. When the core head is installed in the stainless steel pipe, it is necessary to check the pit and prevent the core head from moving backward.
Source: China Pipe Fittings Manufacturer – Yaang pipe fitting Industry Co., Limited (www.yaang.com)