Plastic Mould Parts of Heat-treatment technology & Artwork

Hits: Date:2011-9-22 Font Size:14px 12px
Choose different varieties for plastic mold, the steel chemical composition and mechanical properties of each are not identical, so manufacturing process is different; the route Also, different types of plastic steel mold the heat treatment process are also different. This section mainly introduces the plastic mould manufacturing process route and the characteristics of heat treatment process.
A, plastic mold manufacturing process line
1. Low carbon steel and low alloy steel mold carbon
For example, 20, Cr, CrMnTi 20 steel processing route for: the material-forging scale and annealing and mechanical rough machining billet and cold extrusion forming-recrystallization annealing and mechanical finishing-carburizing and quenching and tempering, polishing and assembly.
2. High alloy permeability carbon mold
For example, 12 CrNi3A 12 CrNi4A steel processing route for: the material-forging scale billet is offensive and high temperature and high temperature, rough machining and tempering machine and machining and tempering carburizing and quenching and tempering, polishing and assembly.
3. The tempering steel mold
For example, 45, 40 Cr etc steel processing route for: the material-forging scale billet and machinery and rough machining, annealing and conditioning mechanical finishing-nap, polishing and assembly.
4. Carbon tool and alloy tool steel mold
For example T7A ~ T10A, CrWMn SiCr, 9 steel processing route for: the material-forging ChengMo billet and the ball annealing and machinery, rough machining stress relieving and machinery, mechanical machining precision and a half, quenching and tempering, polishing and assembly.
5. The hard steel mold
For example NiSiCa 5, 3 Cr2Mo (steel) applications. For directly use the great materials processing, because supply has some preliminary state hardening treatment, which can be directly processed after forming polishing, assembly. For to change into blank forging again after forming, the process of processing route as: the material to change and the annealing and forging ball milling planer or six surface-pre-hard processing (34 to 42 HRC)-mechanical stress relieving, rough machining, polishing machine and machining and assembling.
Second, the plastic mold heat treatment characteristics
(a) seepage of carbon steel plastic model of heat treatment of characteristics
1. With high hardness and high wear resistance and high toughness requirements of plastic mold, should choose carburizing steels to produce, and put the cementite, quenching and tempering low temperature as final heat treatment.
2. Carburizing layer to the requirements of the general carburizing layer, the thickness of 0.8 ~ 1.5 mm, when pressing including hard packing plastic die carburizing layer thickness requirements for 1.3 ~ 1.5 mm, the suppression of soft plastic carburizing layer when thickness of 0.8 ~ 1.2 mm. The carbon content of carburizing layer is 0.7% ~ 1.0% is preferred. If you use carbon, nitrogen, the wear resistance of permeability, corrosion resistance, oxidation resistance, viscous better.
3. Carburizing temperature is in commonly 900 ~ 920 ℃, complex cavity of small mould desirable in 840 ~ 860 ℃ temperature of carbon nitrogen seepage. Carburizing time of heat for 5 ~ 10 h, specific should according to the requirements of the hydrogenized layer thickness to choose. Carburizing to USES hierarchical carburizing advisable, namely high temperature stage (900 ~ 920 ℃) in a quick carbon into parts surface for the Lord; Temperature stage (820 ~ 840 ℃) to increase carburizing layer thickness, such as carburizing layer in established within the uniform and reasonable carbon concentration gradient distribution, facilitate direct quenching.
4. After carburizing of quenching process according to different kinds, carburizing can be used again after respectively: heating quenching; Grading carburizing directly after quenching (such as alloy carburizing steels); Temperature, carbon and nitrogen were permeability directly after quenching (such as pure iron or low carbon steel with industrial cold extrusion forming the small precision mould); After carburizing air cold hardening (such as high alloy seepage of carbon steel is big, medium-sized mould). (2) a hardened steel plastic model of heat treatment
1. Shape quite complicated mould in rough machining, heat treatment, and then after that is precision can ensure that heat treatment deformation, when the minimum for precision mould, deformation should be less than 0.05%.
2. Plastic model cavity surface, therefore is very strict in quench heating process to ensure cavity surface oxidation, not not not erosion, not decarburization, overheating, etc. Should be in protective atmosphere in the furnace or in the salt bath of deoxidizing strict after heating furnace, if using common box resistor-stove heating, should be in the cavity surface protective coating, and to control the heating, cooling speed should be to choose a moderate cooling medium, control the cooling speed, in order to avoid quenching process deformation and cracking and scrap. General with hot bath quenching for beautiful, also can use the cold hardening way.
3. After quenching should be tempering, tempering temperature to be higher than the working temperature of mould, tempering time should be fully, long shortsighted die material and section size and calm, but should be at least 40 to 60 min above.
(3) the hardened steel plastic model of heat treatment
1. The hard steel is hard to supply the state, generally do not need to heat treatment, but sometimes need to undertake to forging, change the mode of the billet after forging to heat treatment.
2. The hardened steel heat treatment usually adopt advance spheroidization annealing, the purpose is to eliminate forging stress, obtain homogeneous globular pearlite organization, reduce hardness, improve the plastic mould billet, improve the cutting performance or cold extrusion forming performance.
3. The hardened steel pre-hard treatment process of simple, most the quenching and tempering treatment, after adjusting quality for tempering soxhlet body organization. The temperature of the high temperature tempering a wide range of mould can meet all kinds of work hardness requirement. Because this kind of steel its quench-hardening ability is good, hardened by oil can be cold, and air cold or XiaoYan grading quenching.
(4) aging sclerosis of plastic die steel heat treatment
1. Aging sclerosis heat treatment process of steel basic process in two steps. First, the solid solution treatment is heated to a high temperature, steel to make all kinds of alloy elements into austenitic, completion austenitic after quenching obtain martensitic organization. The second step for aging treatment, use limitation to strengthen the mechanical properties of the last request.
2. Solid solution heat treatment furnace, general in salt bath box, heating time furnace are desirable: 1 min/mm, 2 ~ 2.5 min/mm, quenching by oil cold, its quench-hardening ability can also be good kind air cooling. If the forging die casting accurate control can end temperature, after forging forging directly solid solution quenching.
3. Aging treatment in vacuum furnace best, if in the box in the furnace, to prevent the cavity surface oxidation furnace, shall protect access atmosphere, or use alumina powder, graphite powder, casting iron, in boxing protection conditions limitation. Packing list to extend insulation protection heating time, otherwise it is difficult to meet the aging effect.
Three, plastic model of surface treatment
In order to improve the plastic die surface wear resistance and corrosion resistance, often on the appropriate surface treatment.
1. Plastic die chrome is used most of the surface treatment methods, plating chromic layer in the atmosphere has strong ability can keep for a long time, the passivation metal luster, in DuoZhong acid medium are not produce chemical reaction. Coating hardness of 1000 HV, thus has good abrasion resistance. Plating chromic layer also has high heat resistance, in the air when heated to 500 ℃ the appearance and hardness is still no change.
2. Permeability nitrogen has processing low temperature (550 ~ 570 ℃ for general), mould deformation and permeability of hardness little high (up to 1000 ~ 1200 HV) and other advantages, which is also very suitable for plastic model of surface treatment. Contain chromium, molybdenum, aluminum, vanadium and titanium alloy elements of steel grade.these steel is better than carbon nitrogen performance, used as permeability plastic die in permeability nitrogen treatment can greatly improve abrasion resistance.
Is suitable for the plastic model of surface treatment methods and: carbon nitrogen of permeability, and chemical nickel plating, ion plating nitriding titanium, titanium carbide or carbon nitriding titanium, PVD, CVD hard film deposition method or the hard film, etc.