小口径无缝钢管与焊管不同点在哪里？

说是外径小的钢管，就可以称为小口径钢管，小口径厚壁钢管还可以分为：无缝小口径钢管和直缝（也可以称为焊接）小口径钢管，一般在钢管的外径89以下的，都可以统称为小口径钢管按生产方法不同可分为热轧管 、冷轧管 、冷拔管 、挤压管等， 热轧无缝管一般在自动轧管机组上生产。实心管坯经检查并清除表面缺陷截成所需长度， 在管坯穿孔端端面上定心 然后送往加热炉加热 在穿孔机上穿孔 在穿孔同时不断旋转和前进， 在轧辊和顶头的作用下， 管坯内部逐渐形成空腔称毛管， 再送至自动轧管机上继续轧制后经均整机均整壁厚， 经定径机定径， 达到规格要求， 利用连续式轧管机组生产热轧小口径钢管是较先进的方法， 若欲获得尺寸更小和质量更好的小口径钢管， 必须采用冷轧 冷拔或者两者联合的方法冷轧通常在二辊式轧机上进行，小口径钢管在变断面圆孔槽和不动的锥形顶头所组成的环形孔型中轧制， 冷拔通常在单链式或双链式冷拔机上进行 挤压法即将加热好的管坯放在密闭的挤压圆筒内穿孔棒与挤压杆一起运动， 使挤压件从较小的模孔中挤出， 此法可生产直径较小的钢管。

英文版：Small diameter steel pipe, can be called small diameter steel pipe, small diameter thick-walled steel pipe can also be divided into: seamless small diameter steel pipe and longitudinal seam (also known as welding) small diameter steel pipe, generally in the steel pipe under the outer diameter of 89, can be collectively called small diameter steel pipe according to different production methods can be divided into hot-rolled pipe, cold-rolled pipe The hot rolled seamless pipe is usually produced on the automatic tube rolling mill. The solid billet is inspected and the surface defects are cleared and cut to the required length. The billet is centered on the end face of the piercing end of the billet and then sent to the heating furnace for heating. The piercing machine rotates and advances continuously during the piercing. Under the action of the roll and the head, the billet gradually forms a cavity called capillary, which is then sent to the automatic pipe mill to continue. It is an advanced method to produce hot-rolled small-diameter steel pipes by continuous rolling mill. If small-diameter steel pipes with smaller size and better quality are to be obtained, cold-rolled cold-drawn or combined cold-rolled two-roll mill is necessary. The small diameter steel pipe is rolled in a circular pass consisting of a variable section circular groove and a stationary tapered plug. Cold drawing is usually carried out on a single or double chain cold drawing machine by extrusion. The heated billet is placed in an airtight extrusion cylinder and the punch rod moves with the extrusion rod, so that the extruded part is smaller. This method can produce smaller diameter steel pipes.