Perforated molybdenum piercing head structural member

Abstract

The invention relates to the seamless steel tube production equipment and discloses a perforated molybdenum piercing head structural member. The perforated molybdenum piercing head structural member comprises a piercing head and a connecting joint; the piercing head is formed by a piercing area, a roll-off area and an adhering to round area; the length of the roll-off area is 75 to 90 % length of the piercing area; the connecting joint is in a hollow shape; one end of the connecting joint is a blind hole and a middle section of the connecting joint is provided with steps which are radially provided with cooling water outlet holes; the blind hole end of the connecting joint is in internal thread connection with the piercing head; the other end of the connecting joint is in internal thread connection with a piercing rod; and an inner hole is provided with a cooling pipe. The perforated molybdenum piercing head structural member has the advantages of enabling internal surface quality of a capillary pipe to be good, enabling surface fracturing and surface sticking which are generated on a full molybdenum piercing head to be reduced, improving the service life by four times and greatly decreasing workloads and auxiliary material consumption in artificial polishing and changing.

Description

technical field [0001] The invention relates to seamless steel pipe manufacturing equipment, in particular to a perforated molybdenum plug structure. Background technique [0002] With the rapid development of the power generation industry, the boiler industry has put forward higher requirements for the seamless steel pipe materials used. Due to the 2010 edition of the "ASME Boiler and Pressure Vessel Code" published by Sinopec Press Standard ASME SA-213 / SA-213M "Seamless ferritic and austenitic alloy steel pipes for boilers, superheaters and heat exchangers" T91 grade and ASME SA-335 / SA-335M "Seamless ferrite for high temperature Alloy steel pipe" P91 grade high-strength seamless steel pipe has good process performance and mechanical properties, and has been widely used in the boiler industry. The development of T91 and P91 grade seamless steel pipe has become a trend for seamless steel pipe manufacturers at home and abroad . [0003] At present, there are many types of p...

AI Technical Summary

Problems solved by technology

[0004] Since T91 and P91 grade steels are alloy steels with high strength and narrow deformation temperature range, traditional oxide film plugs (20CrNiSiW steel) and H13 steel (molybdenum-inserted, welded molybdenum, composite) plugs cannot effectively meet the requirements of tube billet piercing and rolling. process requirements

Among them: during the perforation process of the traditional oxide film plug, each plug can only pass through one capillary tube. If more than two capillary tubes are worn, the perforation area of ​​the existing plug will be L 1 'The head will have surface metal accumulation, collapse, cracking, and cause accidents such as rolling jams and ejector rods; during the perforation process of the H13 steel plug series, the existing plug perforation area L will appear. 1 'The molybdenum pillars welded together on the head fall off, causing the plug to fail, and if it is serious, it will cover the plug; and although the current all-molybdenum plug can roll 80 pieces on average during the piercing process, there are still the following problems: (1) Due to the existing head rolling area L 2 ′ is too short and conical, and the quality defect of the inner surface of the capillary is caused by incomplete rolling, which is rejected and the yield is low; (2) The cooling water directly contacts the all-molybdenum plug, rapid cooling (before and after piercing) and rapid heating (during piercing) Under working conditions, the all-molybdenum plug is prone to surface cracks and needs to be replaced frequently; (3) Since the cooling water directly contacts the all-molybdenum plug, the surface of the existing plug 1′ has serious iron sticking during the rapid cooling and rapid heating piercing process, and iron sticking on the surface occurs Afterwards, it needs to be ground gradually before it can be pierced and rolled again. Not only does the labor intensity of the employees increase, but also the surface temperature of the existing plug 1′ needs to be preheated again after the surface temperature drops, and the consumption of auxiliary materials increases.

[0005] The above-mentioned problems lead to the reduction of the service life of the oxide film, H13 steel, and all-molybdenum plugs, and the frequency of manual replacement increases. Not only the consumption of the plugs is high, but also the inner surface of the capillary is defective due to incomplete rolling. Very high, low yield at one time

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