Production process of steel pipe hot rolling mill
 
We usually call the wall thickness processing of capillaries tube rolling.
Pipe rolling is the most important process in the forming process of steel pipes. The main task of this link is to reduce the thickness of the thick-walled capillary tube to the degree compatible with the finished steel tube according to the requirements of the finished steel tube, that is, it must take into account the change in wall thickness during subsequent determination and reduction processes. The uniformity of the internal and external surface quality and wall thickness. The pipe after the pipe reduction and extension process is generally referred to as a waste pipe.


 
The basic feature of the tube rolling wall reduction method is to press the rigid core rod inside the capillary tube and reduce the wall thickness of the capillary tube by an external tool (roller or die hole). According to different deformation principles and equipment characteristics, it has many production methods, as shown in Table 1.
 
It is customary to name hot rolling mills based on the form of the rolling mill. The rolling mill is divided into single rack and multiple racks. The single rack includes automatic pipe rolling mill, Assel rolling mill, ACCU-ROLL, etc. The inclined pipe rolling mills are all single racks; Usually 4 ~ 8 racks, such as MPM, PQF, etc. At present, two kinds of tube rolling processes: continuous rolling (belonging to vertical rolling) and diagonal rolling are mainly used.
 

Deformation principle	Equipment and tool features				Processing technology	Elongation factor
	External tools, equipment			Mandrel
Longitudinal rolling	Single rack			Short (fixed)	plug mill	1.5~2.1
	Multi-stand continuous rolling			Long (floating)	MM	3~4.5
				Mid-length (semi-floating, limited motion)	Neuval-R，MRK-S、MPM、PQF	3~6.5
Diagonal rolling	Two rolls	Guides		Short (fixed, limited)	Secondary punching and stretching machine	＜2.5
		Guide plate		Long (floating)	Diescher extension machine（Diescher）	2~5.0
				Medium (limited motion)	ACCU-ROLL	2~5.0
			Three rolls	Medium and long (floating, limited, rollback)	Three-roll tube mill (Assel, Transval)	1.3~3.5
			Multi-roller	Medium (fixed)	PSW	5~14
Forging	Cycle Section Roller			Medium (reciprocating)	Periodic Tube Rolling Mill (Pilger)	8~15
Pipe jacking	Row of die holes			Long (synchronized with outlet pipe end)）	Pipe jacking machine	4~16.5
Extrusion method	Single-mode hole			Medium (fixed)	Extruder	1.2~30