CN103667816A

CN103667816A - Process for casting spindle crank arm box shell

Info

Publication number: CN103667816A
Application number: CN201210343400.3A
Authority: CN
Inventors: 宗习洪; 王飞; 曾鸣; 席建东
Original assignee: JIANGSU HUAJIANG TECHNOLOGY Co Ltd
Current assignee: JIANGSU HUAJIANG TECHNOLOGY Co Ltd
Priority date: 2012-09-17
Filing date: 2012-09-17
Publication date: 2014-03-26

Abstract

The invention relates to a process for casting a spindle crank arm box shell. The process comprises the steps of casting by adopting an A356.2 aluminum alloy liquid containing 0.1-0.2wt% of strontium, re-smelting, then performing refining degasification treatment without additionally adding strontium, then pouring after standing for 10 minutes, and smelting for 2-4 hours to obtain the shell. The process disclosed by the invention has the beneficial effects that a metallographic structure is tiny in crystalline grain and uniform in distribution with eutectics which are fibrous; the mechanical properties are improved, the tensile strength is more than 290MPa, the extensibility is more than 5%, and the hardness is more than 100; and the pinhole degree level is high and reaches level 0-1, namely no pinhole exists. The product is stable and reliable in quality, the production efficiency is improved and the production cost is reduced.

Description

Main shaft crank arm box shell casting technique

Technical field

The present invention relates to the main shaft Crankarm box shell for GIS high-tension switch gear of a kind of electric line mesohigh substation.

Background technology

GIS full name gas insulated combined electrical equipment, all facilities in Jiang Yizuo substation except transformer, comprise isolating switch, isolator, grounding switch, voltage transformer, current transformer, thunder arrester, bus, cable terminal end, inlet-outlet sleeve etc., through optimization design, be organically combined into an integral body, and the present invention is the key part of this equipment, resistance to air loss and resistance to pressure require high, otherwise the leakage due to SF6 gas, the factor impacts such as the infiltration of outside moisture, all may cause GIS internal flashover fault, the all-sealed structure of GIS makes the location of fault and overhauls more difficult, service work is numerous and diverse.

At present, the present invention adopts A356 cast aluminium alloy material conventionally, needs to improve product mechanical property through rotten processing, conventionally adopts strontium (Sr) as alterant, and modification effect is good, and the length of holding time, belongs to long-acting alterant.Tradition adds Sr modification technique, first will be not containing the A356.2 Cast aluminium alloy ingot remelting of strontium, do not arrive after certain temperature, add 0.2～0.6% strontium before refining treatment, strontium alterant needs one section of rotten processing incubation period, after refining degasification, need standing more than 30 minutes, could fully play metamorphism, production efficiency reduces, and the rotten incubation period of strontium is short, skewness, metallographic structure eutectic is point-like, vermiform, has part short strip shape, has indivedual fritter shape primary silicons.Because time of repose is long and the add-on of strontium is high, strontium is rising a metamorphic while, and product pin hole is increased, and pinhole rate reaches 2～3 grades, thereby affects resistance to air loss, resistance to pressure and reduction work-ing life of product.Its content of strontium adds height, and production cost increases.

Summary of the invention

The deficiency that " need to add that strontium is rotten to be improved metallographic structure and improve mechanical property; and strontium alterant is playing a metamorphic while; can impel foundry goods pin hole to increase the weight of " in order to overcome existing main shaft Crankarm box, the invention provides a kind of main shaft Crankarm box shell, can not only solve the serious negative impact of pin hole, and bring into play more fully the modification effect of strontium alterant, improve mechanical property, after refining degasification, do not need long time of repose, improved production efficiency, reduced production cost.

The technical solution adopted for the present invention to solve the technical problems is: while founding A356.2 aluminum alloy ingot, do not changing on the basis of principal element content, the strontium alterant that adds mass ratio 0. 1-0.2%, add-on adds strontium technique lower than tradition, in aluminum alloy ingot reflow process, inhale hydrogen few, after refining degassing processing, without long time of repose, only need within standing 10 minutes, can use, the melting of 2～4 hours forms shell.Strontium alterant adds when founding aluminum alloy ingot, although add-on is few, strontium is when founding aluminum alloy ingot, alloy liquid has carried out rotten for the first time, when aluminum alloy ingot remelting, carried out going bad for the second time, anteroposterior diameter is crossed twice and is gone bad, and has given full play to the metamorphism of strontium alterant.After thereby solution traditional technology adds strontium, aluminum alloy melt suction hydrogen is inclined to large, the serious object of pin hole, has improved product mechanical property simultaneously.

The invention has the beneficial effects as follows, metallographic structure crystal grain is tiny to be evenly distributed with eutectic, and it is fibrous that eutectic becomes; Improved mechanical property, tensile strength is greater than 290MPa, and unit elongation is greater than 5%, and hardness is greater than 100; Pinhole rate grade is high, and pinhole rate grade reaches 0-1 level, there is no pin hole.Stable and reliable product quality, has improved production efficiency, has reduced production cost.

Accompanying drawing explanation

Fig. 1 is metallographic structure analysis figure of the present invention.

Fig. 2 is existing metallographic structure figure.

Embodiment

Do not changing on the basis of original chemical composition, while founding A356.2 aluminum alloy ingot, in aluminium alloy, adding the strontium alterant of 0.01-0.02%, after aluminum alloy ingot remelting, no longer additionally add strontium, after refining degassing processing, standing 10 minutes pourable, and the melting of 2～4 hours forms shell.

Table 1 A356.2 aluminum alloy chemical composition

The contrast of table 2 mechanical property

?	Tensile strength (MPa)	Unit elongation (%)	Hardness (HBS)
				Original invention	270	3	90
Existing invention	290	5	100

Claims

1. main shaft crank arm box shell casting technique, is characterized in that, adopts and contains the A356.2 aluminum alloy melt casting that strontium mass percent is 0.1～0.2%, after remelting, additionally do not add strontium, after refining degassing processing, cast in standing 10 minutes, the melting of 2～4 hours forms shell.