直縫（féng）焊管（guǎn）擴（kuò）徑是其中一種使用滾壓或機械方法從（cóng）焊管內壁運力使焊管（guǎn）本著通往向外（wài）擴脹有關成型的壓強進行加工生產工藝。機械方法比滾壓方法，設備（bèi）更為簡便且工作（zuò）效率更高（gāo），在（zài）全球上首先進的關於（yú）幾條花木（mù）一直縫焊管製線坯子擴徑生產線都被使用，其（qí）生產工藝為： 機械擴徑（jìng）使用擴徑機（jī）端部的分瓣的錐形塊沿通往（wǎng）擴大，使管坯沿長度大方向以（yǐ）步進等（děng）級方（fāng）法，分支（zhī）達成全管長（zhǎng）塑（sù）性變形蛻變的完整過（guò）程。進行（háng）劃成5個當前階（jiē）段。
Diameter enlargement of straight seam welded pipe is a kind of pressure processing technology, which uses hydraulic or mechanical method to force the welded pipe from the inner wall to make the welded pipe expand radially outward. The mechanical method is simpler and more efficient than the hydraulic method. In the world, the most advanced expanding process of large diameter straight seam welded pipe line is adopted. The process is that the mechanical expanding expands along the radial direction by using the sector block at the end of the expander, so that the billet can realize the plastic deformation of the whole length of the pipe in a step-by-step manner. It is divided into five stages. 1、大致整圓當前階段。錐（zhuī）形塊進行表（biǎo）示截至全部（bù）錐（zhuī）形塊都進行聯係到焊（hàn）管內壁（bì），這陣兒（ér）步長適用範圍內焊缸（gāng）管圓管（guǎn）中各點球體大大小小都差不多保持一致，焊管（guǎn）獲得大致整圓。
1. Preliminary rounding stage. The sector block opens until all the sector blocks touch the inner wall of the welded pipe. At this time, the radius of each point in the welded pipe is almost the same within the step size range, and the welded pipe is initially rounded.
2、有名無（wú）實內（nèi）徑當前階（jiē）段。錐形塊過去段所在地進行首先進一步減少活動運行速度（dù），截至到達具體要求所在地，這一所在地是質量具體要（yào）求的產品缸管圓周所在地。
2. Nominal inner diameter stage. The fan-shaped block reduces its motion speed from the front position until it reaches the required position, which is the circumferential position of the finished pipe required by the quality.
3、彈（dàn）複補充當前階段。錐形塊在2當前階段的所在地（dì）進行首先進一個（gè）步驟將中速度，截至到（dào）達具體要求所在地，這一所（suǒ）在地是（shì）生產工藝設計具體要求的（de）彈（dàn）複（fù）前焊缸管圓周所在地。
3. Rebound compensation stage. The sector block will start at a lower speed at the position of phase 2 until it reaches the required position, which is the circumferential position of the pre-spring welded pipe required by the process design.
4、保壓保持穩定當前階段。錐形塊在彈複前焊缸管圓周所在地關於一段時段（duàn）繼續維持不動，這（zhè）是設備和擴（kuò）徑生產（chǎn）工藝（yì）具體要求的保壓保持（chí）穩定當（dāng）前階段（duàn）。
4. Pressure-holding and stabilization stage. The sector block remains stationary for a period of time in the circumference of the welded pipe before resilience, which is the pressure-holding and stabilizing stage required by the equipment and the expanding process.
5、卸荷進行回來當前階段。錐形塊從彈複前焊（hàn）缸管圓周所在地進行首先（xiān）較為飛速回縮，截至到達進行開始擴徑（jìng）的所在地，這是擴徑生產工（gōng）藝具體要求的錐形塊（kuài）短（duǎn）小減少有關直（zhí）徑。 在具體應用中，生產工藝優惠中，2、3步子能夠統一優惠，這對（duì）焊管的擴徑質（zhì）量並未產生相應作用。
5. Return stage of unloading. The sector block shrinks rapidly from the circumferential position of the welded pipe before resilience until it reaches the initial enlargement position, which is the minimum shrinkage diameter of the sector block required by the enlargement process. In practical application, 2 and 3 steps can be combined and simplified in the process simplification, which has no effect on the quality of welded pipe diameter enlargement.
