Forming of large size seamless pipe fittings

Apr 7


Henary Lee

Henary Lee

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Large size seamless pipe fittings forming technology are: hot spinning method, hot extrusion, hot piercing rolling method, heat flaring method to push the system.


1, Forming of large size seamless pipe fittings Articles hot spinning methodSpinning is flat or hollow billets fixed on the spinning machine mold, the blank random bed while rotating spindle, driven by spin wheel or stick pressure in the blank, to produce local plastic deformation. In the feed movement and rotational movement of the rotary joint action of the blank, so that local plastic deformation gradually extended to the entire surface of the blank, and close to the mold, complete spinning parts. Advantages of the spinning process is relatively simple equipment and tooling (not available dedicated lathe instead when spinning machine), in addition to forming such as cylindrical, conical, parabolic or rotate in vitro formation of various other curved lines, but also fairly complex shape machining rotating body parts. The disadvantage is that low productivity, greater labor intensity, more suitable for prototype and small batch production. It is a flat blank or pre-formed blank fixed to the rotating mandrel wheel spin to put pressure on the blank, spin the wheel at the same time as the axial feed, after one or more processing to obtain a variety of thin-walled hollow rotary system Commodities process method. The advantage is the product of high precision, good mechanical properties, a wide range of sizes. Mold tool is simple, easy to replace, the production cost is lower than other methods. The main disadvantage is the production of long working hours, low output, the processing of the tube by the device length limit, short size.

2, hot extrusion methodHot extrusion technology is a metal in the recrystallization temperature or higher, extrusion, so that the tube extruded from a die orifice to obtain a cross-sectional shape of the die hole of the metal pipe molding method. Throughout the hot extrusion process (from tube to tube shortage), the tube is in a three-state deformation of compressive stress. This not only can solve difficult deformable steel pipe molding problems, but also avoids the blank pipe inside and outside surface defects caused by the tensile stress. So hot extrusion method is particularly suitable for a variety of alloy steel, stainless steel, high-strength steel, nickel-based superalloy, such as profiles, molded pipe. Before extrusion billet machined need pretreatment, when squeezing the tube diameter of 100mm or less, equipment investment is small, less material waste, the technology is more mature. However, once the pipe diameter method increases, hot extrusion requires large tonnage and high-power devices, the corresponding control system must be upgraded.

3, hot piercing rolling methodHot piercing rolling mill with vertical extension and cross rolling extension based. Vertical extension of the rolling mill is mainly limited MPM rolling chassis less MPM tube rolling, three-roll MPM pipe rolling and floating mandrel mill rolling. These methods are high efficiency, low consumption of metal, good product quality, advanced control system, used widely. Oblique Rolling rolling method with less investment, short process, suitable for low-volume, multi-species, multi-standard and high precision in the production of seamless pipes and the same has been widely used. In the seamless steel pipe production, the role of the perforation process is solid, hollow tube through a capillary. The entire production process generally include perforation, rolling and fixed reducing processes. As the first step of perforated metal deformation, piercing the pipe wall thickness is thicker, shorter length, the inner and outer surfaces of poor quality, so called capillary. If there are some defects in the capillary, through the later step is difficult to remove or mitigate. So perforation process plays an important role in modern steel production.

4. The method of expanding hot push the systemPush system expanding device is simple, low cost, easy maintenance, economical, durable, flexible product specifications change, such as the need to prepare large-caliber elbow and other similar products, you only need to add some accessories to. Suitable for the production of thin-walled seamless steel pipe diameter Heavy material, also can produce no more than the capacity of the thick-walled tube equipment.