The relevant knowledge of aluminium alloy die forging

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One, taller than intensity, conductivity mixes aluminium alloy and its forgeability aluminium alloy thermal conductivity is good, fight corrode ability strong, in a variety of industry domains, apply in aviation industry especially extensive. Be out of shape aluminium alloy has antirust aluminium alloy to wait like 3A21 (LF21) commonly usedly, forging aluminium alloy is like 2A50(LD5) , 2A14 (LD10) to wait, duralumin alloy is like 2A12 (LY12) to wait, exceed duralumin alloy to wait like 7A04 (LC4) . Be out of shape the main alloying element of aluminium alloy has copper, magnesian, zinc, manganese, nickel, titanium, zirconium to wait. Copper, magnesium and zinc can form aggrandizement photograph with aluminium, make aluminium alloy aggrandizement; Manganese can raise aluminium alloy fight corrode ability. Forging used aluminium alloy has better plasticity mostly, can have all sorts of die forging technology. The plasticity of aluminium alloy basically suffers alloy composition and be out of shape the influence of temperature, the plasticity of aluminium alloy of certain high strenth still is had be out of shape apparently speed sensitivity. Generally speaking, as the addition of alloying element, the plasticity of aluminium alloy is reduced, and the alloying element in aluminium alloy is jumped over much, mix in heat treatment heat the liability that leftover stress produces in the following cooling process is bigger also. 3A21, 2A50 and 7A04 the unit pressure curve of 3 kinds of aluminium alloy, see by the graph, 3A21 is in in 300 ℃ , 2A50 350 ℃ eventually when forge, increase as deformation, unit pressure curve maintains a level, this explains treatment sclerosis and recrystallization bate offset each other, when accordingly these two kinds of alloy are forginging, press such eventually forge temperature, can make alloy is in complete heat to be out of shape condition. Exceed duralumin 7A04 to unit pressure curve increases along with deformation and lift somewhat when 350 ℃ , this explains this alloy is in 350 ℃ eventually forge machines sclerosis from time to tome, unwarrantable complete heat is out of shape; When 400 ℃ , after deformation exceeds 30% , unit pressure increases along with deformation and drop somewhat, the reason is fuel factor warms up caused local bate. 2, aluminium alloy die forging produces an essential 1. The semifinished product that forging of next makings aluminium alloy use has ingot casting and extruding strong capable person. Ingot casting is used at forginging the modular forging with lesser anisotropy, modular forging uses the forging stock after forginging by ingot casting classics. Use at forginging ingot casting to must be made change processing equably in order to improve plasticity. Great ability course is out of shape beforehand, plasticity has gotten rising, undertake die forging easily, but anisotropy of this kind of semifinished product is big, and the watch is annulus of thick any crystalline substance, statified wait for blemish, these surface layer blemish must keep clear of before die forging, it is to be in commonly the skin gathers up on lathe. Aluminium alloy is multi-purpose the makings below sawing machine. Curium the acute margin that cuts generation or burr, need to clear, lest forging when cause defect. automation curiums cut facility, have more pour horny competence automatically, control semifinished product length, bulk and weight accurately. Cutting next material also is the method with commonly used aluminium alloy. Aluminium alloy is softer, the end panel when cutting the material below the bed owes level off, and easy generation crackle, burr, use at the diameter to be less than the great ability of 50mm commonly. When next makings precision demands are high, can use the material below lathe, milling machine. 2. Hot normative aluminium alloy heats before forge can use a variety of heating installation, but had better use resistor furnace to heat, when using gas furnace or oily heat, want those who add control fuel to father contain sulfur content, lest sulfur infiltration crystal boundary causes crackle. Had better contain inside furnace force furnace to enrage circular device, in order to make furnace temperature even. The blaze inside furnace does not allow direct eject to arrive semifinished product surface. Cannot heat aluminium alloy semifinished product and steel together, aluminous bits and oxidation scrap lump produce explosion easily. Foreign aluminium alloy forgings heat to often also choose muffle. Of aluminium alloy forging temperature range is narrower, control in 150 ℃ commonly, of aluminium alloy of certain high strenth forging temperature interval is less than 100 ℃ even. For example 7A04 exceeds duralumin, its are main aggrandizement photograph is Mg2n2 and Al2 CuMg compound, al and Mg2n2 are formed in all brilliant, its fuse temperature is 470 ℃ . Accordingly, its only then forge temperature is low to 430 ℃ . On the other hand, the anneal of 7A04 alloy heats temperature is 390 ℃ , this explains it has higher recrystallization temperature, so of alloy eventually forge temperature takes 350 ℃ . Such, of 7A04 alloy forging temperature limits has 80 ℃ only. Watch 7-3 is listed and commonly used be out of shape of aluminium alloy forging temperature limits. Watch 1 commonly used be out of shape of aluminium alloy forging temperature although of aluminium alloy forging temperature range is narrower, but, the time of die forging process is more abundant however. Because opposite at aluminium alloy forging temperature says, the warm-up temperature of the mould is higher, and as a result of aluminium alloy be out of shape fuel factor is bigger, the temperature when forginging rises possibly still somewhat. Aluminium alloy thermal conductivity is good, because this semifinished product does not need to undertake warm-up, can be in directly furnace of high temperature remove theatrical makeup and costume. But heat time is longer than general carbon steel, this is when heating because of aluminium alloy, must make sure in-house aggrandizement photograph dissolves adequately, so that make alloy organization even, plasticity rises. The diameter is less than the semifinished product of 50mm, heat time presses diameter or ply 1.

5min/mm computation, the diameter is more than the semifinished product of 100mm, press 2min/mm computation, the diameter is in the semifinished product inside limits of 50 ～ 100mm, press type is calculated. T=l.

5+0.

01 × (of diameter of every millimeter of the T- in D-50) type or ply heat time Min; The diameter of D- semifinished product or ply, mm. The property of the deliquescent process of aggrandizement photograph and aggrandizement photograph, size, appearance, distributing about, the organization is bulky deliquescent slow, so ingot casting, large semifinished product should be taken heat the upper limit of time; The aluminium alloy with alloying element high content, heat time is some longer. The forging after forginging, pile up in air commonly cooling. 3. Die forging of die forging aluminium alloy can undertake on a variety of die forging equipment. To raise plasticity, reduce be out of shape fight the force, liquidity that improves alloy, the effect that chooses compressor to compare hammer is close friends some. Mechanical compressor and helix compressor are appropriate the forging that accumulates at producing medium dimension, general interest, use extensively at aluminium alloy to shut type die forging; Forging of large to aluminium alloy model or form are complex, the rigid standard forging that high-definition clear outline does not have die forging rake, had better use hydraulic press die forging, rate of meet an emergency of slow and easy pilot can make aluminium closes be out of shape fight force to fall the smallest, reduce forging pressure is obtained easily expect figure; Pipe fittings, 3 wait small-sized aluminous forging, undertake do not have flash die forging on helix compressor. The fluidity of aluminium alloy is poorer (poorer than steel and titanium alloy, but better than magnesium alloy) , more sensitive to crackle, unfavorable use collect labor situation; Aluminium alloy issues exterior coefficient of friction in high temperature tall, adhere muscularity, unfavorable use roll crowded impression. Forging temperature range is narrow, because this uses single impression die forging commonly, use freedom to forge base. Mould should warm-up arrives 300 ℃ of 250 ～ . The fluidity to increase alloy and facilitate a model, want to undertake polishing to impression surface, the requirement achieves Ra =0.

4 ～ 0.

2tjm above. Because aluminium alloy is right rate of meet an emergency is sensitive have radiative sex, force of the height that good peen should control when forge of hammer upper mould, blow and speed, begin hammer to attack should light, generation flash, after forming favorable stress position, can the bang increases deformation. Be like forge of compressor upper mould, be more than when the deformation of journey 40% when, a large number of metals squeeze the chamfer side Xiang Fei, make impression is full of not easily, can use beforehand forge and eventually forge two working procedure. To the forging with complex form, often use many pattern, for many times die forging, make semifinished product appearance by transfer simply stage by stage complex, flow thereby it is even, easy to fill up, prevent forging to appear grain is inhomogenous wait for blemish. Between working procedure of each die forging, should make excise flash, pickling and keep clear of commonly exterior blemish. Of aluminium alloy be out of shape flow is opposite round horn radius is very sensitive also, small round horn radius causes metallic flow difficulty very easily, generation fold, crackle, fiber breaks off to wait for blemish and lower forging die life, so the round horn radius of aluminium alloy forging compares steel forging commonly big. Normally the round horn radius of small forging should be more than 1 ～ 2mm, large and medium-sized the round horn radius of forging should be more than 2 ～ 5mm. The adhere muscularity of aluminium alloy, die forging rake also answer somes big, the die forging rake that uses normally is 7. , below the case that has ejector, also can use 1. ～ 5. . Muscularity of aluminium alloy adhere, fluidity is poor, because this mould is lubricant,be the important segment of die forging craft. Be opposite small or appearance produces folding forging complexly, easily, the lubricant that uses normally is 80% ～ 90% spindle are oily + 20% black lead of 10% ～ ; To big or the forging with simple appearance, can use 70% ～ 80% steam cylinder oil + 2026, 30% black lead. 4. Cut a margin besides super- besides duralumin, aluminium alloy forging cuts a margin below cold conditions; Large model forging excises flash with band saw, gross rushs to cut or be excised with machining with drift. 5. Clear between die forging working procedure and eventually after forge, forging of aluminium alloy model should undertake pickling, pickling can keep clear of leftover lubricant and oxidation film, get the surface of natural burnish makes blemish is shown clearly come. For example surface of forging of some factory aluminium alloy clears craft: Containing 4% ～ 8% (quality mark) in NaOH aqueous solution, the macerate below 70 ℃ 0.

5 ～ 5min; is instantly below the hot water of 75 ℃ or higher temperature rinse 0.

5 ～ 5 Min; Immerge 88 ℃ , 10% nitric acid (bulk mark) black of the purify in aqueous solution is sedimentary; Be in 60, the full in the hot water of 70 ℃ 3 ～ 5min. 6. The aluminium alloy that repair an injury issues very soft, stickiness in high temperature big, produce all sorts of surface limitation easily (fold, burr, crackle) . Repairing an injury is the important segment in craft of aluminium alloy die forging. The blemish of semifinished product surface must keep clear of clean before die forging, can expand further in the blemish in follow-up working procedure otherwise, cause forging to discard as useless. The tool that long injury uses has milling cutter of pneumatic grinder, pneumatic, dynamoelectric milling cutter and flat shovel to wait. Pickling should be passed before be being repaired and make a thorough investigation of blemish place, the place that repair an injury wants round glide to cross. 3, problem of thick any crystalline substance the tendency that all sorts of is out of shape that aluminium alloy has what degree differs to form thick any crystalline substance to organize. Discover by forging and modular forging thick any crystalline substance is organized lesser, and alloy of 2A1(LD10) , 2A70 (LD7) , 2A02 (LY2) , often discover organization of thick any crystalline substance in 6A02 (LD2) especially. For example, the from the forging on the 2A50(LD5) , 2A11 (LY11) , forging with 2A16 (LY16) alloy whole thick any crystalline substance of 7A04 (LC4) alloy, because raw material thick any crystalline substance or overheat organization place are caused,be more. And local the matter of thick any crystalline substance is complex. The exterior thick any crystalline substance of forging, it is annulus of thick any crystalline substance of great ability surface layer more the result in forging surface bequeath. The annulus of thick any crystalline substance of surface of aluminium alloy great ability makes plasticity becomes poor, when forginging easy generation crackle. When forge of hammer upper mould, begin to answer tat, smash ring of exterior thick any crystalline substance, raise metallic plasticity, add serious blow to make the metal is full of impression gradually again next. In the local place with forging little deformation, often because fall the person is critical deformation and cause thick any crystalline substance. To avoid thick any crystalline substance is formed when recrystallization, eventually below forge temperature be out of shape should keep away from critical deformation (12% ～ 15%) . In deformation convection of photograph of big, metal uses acuteness area, because of grain to tend consistent, and recrystallization energy is very high, likelihood happening collects recrystallization and also form thick any crystalline substance when be handled along with postheat. In addition, deformation crosses hasty of big, forge to count surface of overmuch, mould coarse, eventually forge temperature is low, quench water Wen Gao, time grows wait to be able to bring about generation thick any crystalline substance. Produce thick any crystalline substance particularly easily around forging flash area for example. The tensile strength that organization of thick any crystalline substance can reduce forging significantly, succumb intensity and outspread rate, have undesirable effect to fatigue intensity and aseismatic function, should adopt proper technology measure to prevent defect of thick any crystalline substance. Need a consideration generally speaking: The choice is size of reasonable semifinished product shape, logical make base and beforehand forging pace, reasonable be out of shape one temperature condition, improve appearance of tool, impression even and smoothness or evenness on rubber roll surface, lubricant etc. CNC Milling CNC Machining