Copper reachs the semifinished product forming of copper alloy spare parts
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source:KOMANG CNC Machining
[summary] the research that carries pair of copper and defect of product of copper alloy forging, the improvement that found craft and material bright, this technology is feasible, can satisfy the requirement that product percent of pass raises, can improve product quality. Copper is to have face heart the metal of cubic lattice, not was the same as element abnormity change, accordingly it falls to have tall plasticity in room temperature and high temperature, can undertake cold hot forming. Forginging in production, breed of cupreous simple spare parts is very much, have pure copper and copper alloy (the) such as common brass and silicon brass, have free forging and modular forging, visible form simple or form is very complex. In long-term actual production, put the quality issue that is in a lot of differring, ceng Yin forgings the case that crackle causes workpiece to discard as useless is not little. Experiment through relapsing and forging, to forginging the improvement of craft, to the composition analysis of raw material, to the metallographic analysis of raw material, solved these quality problems basically. Research forgings to talk about a result to experience with respect to what copper reachs copper alloy below. One, of pure copper forging in the pure copper in the past in production, ever because forging,crackle brings about a large number of workpiece to discard as useless. 1. Original case workpiece is the cirque that material is T2 character kind free forging, have 300 a variety of, external diameter 400 ～ 2265mm, internal diameter 300 ～ 2100mm, ply 20 ～ 125mm. Craft uses cupreous ingot forge to unplug after strip, curved circle solders figuration. Use equipment is fuel heating furnace, 7. 5kN air hammer and round curved machine. Forging temperature is 650 ～ 900 ℃ , forging actually temperature is judged by experience. 2. Ingot of quality circumstance copper is in 7. Unplug on 5kN hammer when growing, forge when 5 hammer of 3 ～ , preform surface craze, fore-and-aft, transverse crackle has, but majority is cracked for the horizontal stroke, we use this one technique, these year already produced similar quality problem for many times. 3. Quality is analysed (forging of analysis of 1) chemical composition discards as useless because of crackle in all 10 more than T, every batch sampling detected chemical composition, in all sampling 11. Chemical composition (quality mark) in the average content of Pb exceeds mark O. The average content of 02l ％ , Bi exceeds bid 0. The average content of 0128 ％ , Sb exceeds bid 0. 0007 ％ , matter content all exceeds bid badly. (2) metallographic analyses ① a few metalloid field trash distributing dispersedly, grain is petty. ② metallographic organization is one grain of A, size is inhomogenous, its are average diametical D=O. 1mm, brilliant granuality is equivalent to 11 ～ 12 class. (Discovery forgings to still crackle appears after 3) copper ingot decorticates. (The main reason that crackle produces when 4) analysis and conclusion ① electric annulus are forginging is foreign matter element (Bi, Ph, Sb) exceed bid. The content such as Bi, Pb, Sb exceeds a level greatly, this is influential to cupreous conductivity and plasticity, especially the Ph of excessive and Bi are in the solubility in copper is very small, they and copper form Cu, P11 and Cu, of Bi low melting point in all crystal (melting point is 327 ℃ and 270 ℃ ) accordingly, show meshy distributinging Yu Gurong on the crystal boundary of body, weakened the ask connection of grain, bring about plasticity to be reduced abruptly and craze. ② secondary consideration is only then forge temperature control is lax pass with deflection big. Because forging,temperature is to rely on handlers to see metallic color judge by experience, forging actually temperature holds very hard. Only then when forge temperature is exorbitant, low melting point in all crystal is fused make copper qualitative forging easily craze, cause " hot-shortness " ③ is in only then when forge, deflection is big, as a result of fuel factor, the heighten of temperature also can make low melting point in all crystal is fused, destroy the union between grain, bring about craze. 4. Improve measure (club of round copper of instead of 1) copper ingot, strengthen raw material examination, the chemical element of material must accord with CB5231, the regulation of 200l. (2) forgings temperature is 650 ～ certainly 850 ℃ , forging the measurement of temperature uses far infrared ray to measure Wen Yi. (3) uses electric stove to heat. (4) only then when forge, deformation control is in 15 ％ of 10 ％ ～ . (5) hammer is attacked should light, retroflexion freely lest be lost of quantity of heat. 5. The effect improves what craft reachs material hind to forging in production, eliminated basically forging crackle, quality rises apparently, percent of pass amounts to 95 ％ above. Of nextpage2, copper alloy forging 1. Forging brassily the plasticity of common brass is very tall, be out of shape fight force small also. Brass in 20 ～ 200 ° C and the temperature of 900 ℃ of 650 ～ fall, have very tall plasticity, but in 250 ～ between the temperature of 650 ° C, its plasticity drops, adverse to v figuration. According to brass this one character, to some spare parts in some product (of material H62) forging wove special technology, had a few tests, collected a few data. Elaborate as follows now: (This hardware data is 1) original case H62 is brass, its are mechanical performance demand σ B=580MPa. And the B of mechanical function σ of the raw material H62R that the spare parts uses is controlled for 330MPa, after forginging commonly, the B of mechanical function σ of forging is 400MPa left and right sides, short of designs a requirement. For this, we used cold forging aggrandizement to be out of shape craft will increase mechanical performance, achieve design requirement. (H62 of 2) craft analysis is α + β is brass, it is between 650 ℃ of 250 ～ , plasticity is very low, when v easy craze. When temperature prep above when 800 ℃ , the grain of forging is very bulky, and overheat processing cannot be connected to try to refine again in that way like carbon steel after grain is grown, because this grain is thick,the general makes product function drops. (3) technology program is cracked to prevent workpiece forge, avoid to form bulky grain, assure the mechanical function of workpiece, craft uses high temperature area (forge of semifinished product of 800 ° C) causes 700 ～ form, deflection > 15 ％ ; Microtherm area (200 ℃ are the following) cold forging aggrandizement is out of shape. Undertake forge is produced trying first, junior travel product is produced. (4) plan carries out ① to get the materials ready: Preparation sample 5, except sample the dimension of 1 is (outside 75mm of × of ψ 25 Mm, the others sample size all is ψ 55, nm × 50mm. ② forgings temperature: Hot forge temperature is 700 ～ 800 ℃ ; Cold forging temperature is 100 ～ 200 ℃ . ③ forgings craft: Sample the 1 air after using hot forge take shape is cold, do not undertake cold forging; Sample 2 use radial to unplug long, the air after hot forge figuration is cold to cold forging take shape has when 150 ℃ ; Sample 3 use axial to unplug long, the air after hot forge figuration is cold to cold forging take shape has when 150 ° ; Sample 4 use axial to unplug long, the air after hot forge figuration is cold to cold forging take shape has when 200 ℃ ; Sample 5 use radial to unplug long, the air after hot forge figuration is cold to cold forging take shape has when 200 ℃ , do not control eventually forge temperature. ④ produces a course actually: Ask to undertake by craft. ⑤ forgings result: Sample L ～ 4 all accord with craft requirement, 5 cold forging go to sample the craze when 80 ℃ . ⑥ deformation: Sample the deformation of cold forging aggrandizement of 5 is 1 ～ respectively 0, 20 ％ , 33 ％ , 28 ％ and 40 ％ . ⑦ mechanical function: The B of tensile strength σ of 5 is worth sample L ～ to be 425MPa, 535MPa, 580MPa, 560MPa and 0 (craze to did not do) respectively. (5) sample result analyses a basis sample circumstance, the abecedarian is qualitative the analysis is as follows: ① cold forging is OK aggrandizement is mechanical function, its tensile strength follows the addition of deformation and increase. When ② heats up forge, heat 820 ℃ of temperature ≤ , only then 800 ℃ of forge temperature ≤ , eventually 600 ° of forge temperature ≥ C. When ③ cold forging, deflection cannot big; Cold forging only then 200 ℃ of forge temperature ≤ ; Eventually forge temperature > 80 ℃ . (Of 6) workpiece forging produce what had work according to trying forge result to forging, workpiece quality satisfies design requirement. 2. Silicon forgings brassily silicon brass is the copper alloy that forgings the hardest. Silicon is brass besides the character that has copper alloy, its wearability is very good, but plasticity is otherer and brass low, forging temperature range is very narrow, have 100 ℃ only, and thermal conductivity is very good, be lost of the quantity of heat when forginging is very fast, percent of pass is very low. When forginging at first, percent of pass has 5 ％ left and right sides only. Through the observation that forgings actually, iteration craft analysis and research, and ceaseless improvement and forging for a long time practice, the percent of pass of the product achieved 85 ％ ～ 90 ％ . The craft after improving is as follows: (1) has been controlled strictly forging temperature, especially eventually forge temperature. Use far infrared ray to measure Wen Yi to measure temperature. (2) electric stove heats, want to have enough heat preservation time, make temperature of preform inside and outside even. (Pattern of warm-up hammer anvil, industry, pincers and strong first class want before 3) forge. (When 4) forgings, cannot have " draught " , cannot blow fanner. (5) controls deformation, hammer is attacked should light, preform wants diligent retroflexion. 3, epilogue the article introduced copper and copper alloy to produce a situation actually, elaborated the process that copper pledges forging quality rises and experience a bit. Use these experience produce at forginging in, not only the mechanical performance that improved forging product percent of pass and forging product, and product quality is stable and reliable. CNC MillingCNC Machining