防護罩注射模具設(shè)計-抽芯塑料注塑模含9張CAD及SW三維,防護罩,注射,模具設(shè)計,塑料,注塑,cad,sw,三維 The rmo plastic The plastic is take the relative molecular mass high synthetic resin as the principal constituent.And joins other chemical additives, may plastifies the formation under certain temperature and the pressure the high polymer composition material. The plastic take synthetic resin as the basic raw material, and regards needs to join the suitable chemical additive. The resin is when being heated softens, has the flowing tendency polymer under the exogenic process.It is in the plastic coheres the function ingredient.The resin has mainly decided the plastic type and the basic decision plastic main performance In order to change the chemical additive which the plastic the performance joins to have the padding, the plasticizer and the stabilizer. The plastic variety is many, the performance is also various.Induces, the plastic principal characteristic is as follows: 1. quality light plastic density in the 0.9~2.3g/cm3 scope, approximately is generally the aluminum 1/2, copper 1/6. 2. specific tenacities and are high the plastic the rigidity the intensity and the rigidity although was inferior the metal is better than, but the plastic density is small, therefore its specific tenacity and is quite higher than the rigidity.If the glass fiber reinforced plastics and the carbon fiber reinforced plastics specific tenacity and is all better than the rigidity the steel products, this pseudoplastic commonly used in manufacture satellite, on rocket and missile components. 3. chemical stability performance good plastic para acid, chemistry medicines and so on alkali have the good corrosion resistance ability.Therefore, obtains the widespread application in the chemical equipment as well as the manufactured item for daily use.The commonly used anti-corrosive plastic is the rigid polyvinyl chloride, it may process the pipeline, in the vessel and the chemical equipment spare part. 4. electric insulation performance good plastic has the superior electric insulation performance and bears the arc characteristic, therefore widely applies in the electrical machinery, in the electric appliance and the electronics industry makes the constructional detail and the insulation material. 5. wear-resisting and the anti-attrition`performance good plastic friction coefficient is small, wear resistant, may take the anti-attrition`material, like uses for to make the bearing, components and so on gear. 6. noise eliminations and attract shake the performance to be good. The plastic makes the transmission friction components, the noise is small, attracts the knocking to be good. The thermoplastic is refers in the specific temperature range internal energy heats up and the hardening by cooling plastic repeatedly.For example: Polyethylene, polypropylene, polystyrene and so on. The thermoplastic craft characteristic has following several kinds: One. Contractility The thermoplastic formation contraction form and the thermosetting plastics are similar.The influence thermoplastic formation contraction primary factor has following several aspects: (1) plastic variety: In because the thermoplastic formation process has the change in volume which the crystallization causes, internal stress, models in the residual stress to be big, molecular orientation strong and so on factors, therefore compares the shrinkage with the thermosetting plastics to be big, the directivity is obvious.Moreover, after the drawing of patterns the contraction and post-processing contraction specific heat soundness plastic is also big. (2) models a characteristic: When models a formation, the melt material and the die space surface contact outer layer cools immediately, forms the low density the solid state outer covering.Because the plastic thermal conductivity is bad, causes to model inner layer slow cooling to form contracts the great high density solid state level.Therefore, models a wall to be thicker contracts in a big way. (3) runner form and size: These factor direct influence material flows the direction, the density distribution, guarantees the pressure to make up shrinks the function and the formation time.Uses the direct runner, the runner section big when contracts slightly, but the directivity is obvious. (4) formation condition: The mold temperature, the injection pressure, guarantees presses formation conditions and so on the time to have the direct influence to the plastic product contraction, the mold temperature is high, the melt material cools slowly, the density is high, contracts in a big way, especially to crystallization material, because its change in volume is big, the drum contraction is bigger.The mold distributes whether even also directly affects the plastic product various partial contraction quantity size and the directivity.The injection pressure is high, the melt material viscosity is bad, the level the shear stress is small, after the drawing of patterns the rebound resilience is big, the contraction reduces.Guarantees presses the time to contract also influential.Guarantees presses the time long to contract slightly, but the directivity is obvious. Designs when the mold, should act according to each kind of plastic the contraction scope, models a wall thickness, the shape, the feed head form size, according to the experience determined models various part of shrinkage, again calculates the mold die space size.Models to the high accuracy, designs when the mold should leave leeway repairs the mold leeway, revises the mold gradually after the experimental mold, achieved models a size, the precision request and the improvement formation condition. Two. Fluidity 1. fluid plastic fluid size, may from the plastic relative molecular mass, the fusing index, the Archimedes spiral line length, the apparent viscosity and the flowing compared to and so on carries on the analysis.The relative molecular mass is small, the fusing index is high, the spiral line length is long, the apparent viscosity is small, flows compared to the big plastic, then the fluidity is good.According to the mold design request, may divide into the commonly used plastic fluidity three kinds: (1) fluidity is good: Has the nylon, the polyethylene, the polystyrene, the polypropylene, the acetyl cellulose. (2) fluidity medium: Has the modified polystyrene, plexiglass, metaformaldehyde. (3) fluidity is bad: Has gathers the carbonic ether, the polyphenylene oxide, gathers the sulphone, the fluorine plastic. 2. influence fluid primary factor （1) temperature: Expects warm high then the plastic fluidity increases, but expects the warm convection mobile influence to regard the different plastic different, some influences are big, some influences are small.Therefore in formation time may control the fluidity through the attemperation. （2) pressure: The injection pressure increases fuses the plastic to be big the shear action, its fluidity increases along with it.The polyethylene, the metaformaldehyde extremely is specially sensitive to the pressure response.Therefore time formation may control the fluidity through the adjustment injection pressure. (3) mold structure: The mold casting system form, the size and the arrangement, the cooling system design rationality, melt material flowing factors and so on resistance all directly affect the melt material in die space actual fluidity. Every urges the melt material reduced temperature, the increase flow resistance factor, all can cause the fluidity to reduce.Designs when the mold should act according to uses the plastic the fluidity, selects the reasonable mold structure. Three. Crystallinity Thermoplastic according to its condensation when whether there is appears the crystallization phenomenon to be possible to divide into the crystalline plastic and the amorphic substance plastic two big kinds. The plastic crystallization phenomenon is refers to the plastic from the fusing condition to in the condensation process, but the member arranges into the regular model gradually by the out-of-order free motion condition the tendency one kind of phenomenon. In general, the crystalline plastic is not opaque and translucent, the amorphic substance plastic is transparent.But also has the exceptional case, ABS is the amorphic substance plastic, but is not actually transparent. Should pay attention to following several points regarding the crystalline plastic in the mold design and the choice injection machine-hour: (1)Expects the warm rise the quantity of heat which needs to the formation temperature to be many, must select the plastified ability big equipment. (2)When condensation emits the quantity of heat to be big, the mold must cool fully. (3)After models a formation to contract in a big way, easy to have the shrink hole, the blowhole. (4)Models a wall to be thin, cools quickly, the crystallinity is low, contracts slightly.Models a wall thickness, cools slowly, the crystallinity contracts high in a big way, the physical performance is good.Therefore, should request to the crystalline plastic according to the plastic to control the pattern making to heat. (5)The plastic aeolotropy is obvious, the internal stress is big, after the drawing of patterns models easily to have the distortion warp. (6)The plastic crystallization melting point scope is narrow, easy to occur has not melted the powder to pour into the mold or the jamming feed head. Four. The heat-sensitivity and Shui Minxing the heat-sensitivity is refers to certain plastics to be sensitive to the heat, warm high and in the being heated time long situation can have the color deterioration in the material, falls gathers, decomposition characteristic.Has this kind of characteristic plastic to be called the heat-sensitivity plastic. For example: Metaformaldehyde and so on.In order to prevent the heat-sensitivity plastic appears the color deterioration in the formation process, the decomposition phenomenon, on the one hand may join the heat-stable medicinal preparation in the plastic, on the other hand elected with the screw rod type injection machine, correctly controls the formation temperature and the formation cycle, simultaneously should eliminate the decomposition product promptly, takes the anticorrosion measure to the mold and the equipment. Shui Minxing refers to certain plastics even if only includes the few moisture contents, but in the high temperature, under the high pressure also can have the decomposition characteristic.Must preheat dryly to this pseudoplastic. Five. The stress dehiscence and fusing bursts some plastic counter stress to be sensitive, when formation easy to have the internal stress also the nature crisp easy crack, models can occur under the exogenic process or under the solvent function wipes a row phenomenon.Therefore, besides joins the additive in raw material to enhance the crack resistance, should pay attention dryly to raw material, simultaneously selects the reasonable formation condition and causes to model the shape structure to be as far as possible reasonable. Designs when the mold should increase the drawing of patterns ascent, selects the reasonable feed head and goes against the organization.When formation should adjust the material suitably warm, mold warm, the injection pressure and the cooling time, avoid modelling as far as possible in cold shortness situation the drawing of patterns.After models a formation to have to carry on the post-processing to enhance the crack resistance, eliminates the internal stress. When fuses certainly the index the polymer melt, when constant temperature through spray nozzle, after its speed of flow surpasses certain value, squeezes out the bath surface has the obvious crosswise crack to be called the fusing breakage.Has fusing to burst can affect models a outward appearance and the performance, therefore if choice fusing index high polymer, designs when the mold should increase the spray nozzle, the flow channel and the runner section, reduces the injection speed and enhances the material to heat. Six. The thermal properties and cooling rate each kind of thermoplastic has the different ratio heat capacity, the heat conductivity, thermal properties and so on thermal deformation temperature.Plastic is higher than which the heat capacity when plasticizing the caloric requirement is bigger than, uses the plastified ability big injection machine elected.The thermal deformation temperature high plastic cooling time is short, drawing of patterns morning, after but the drawing of patterns must prevent the cooling strain.The heat conductivity low plastic cooling rate is slow, must cool fully, must strengthen the mold to cool the effect. Each kind of thermoplastic and models a shape according to its variety characteristic, the request maintains the suitable cooling rate.Therefore the mold designs time must according to the formation request establishment heating and the cooling system, controls the mold temperature. The commonly used thermoplastic formation characteristic is as follows: Side1. polyethylene (1) crystalline plastic, the water absorbant small (2) fluidity is extremely good, overflows the value is about 0.02mm, the fluidity is sensitive to the pressure variation. (3) heating time long then easy to have the decomposition 4) cooling rate is quick, must cool fully, designs when the mold must suppose the cold slug well and the cooling system. (5) shrinkage is big, the directivity is obvious, easy to distort, the warp, the crystallinity and the mold cooling condition affect in a big way to the shrinkage, should control the pattern making warm (6) suitably with the high-pressured injection, expects warm must be even, the packing speed should be quick, guarantees the pressure to have to be full. (7) uses the direct runner injection not suitably, otherwise can increase the internal stress, causes to contract non-uniform and the directivity is obvious.Should pay attention to the choice runner position. 2. polypropylene (1) crystalline plastic, the water absorbability is small, easy to have the decomposition. (2) fluidity is extremely good, overflows the value is about 0.03mm （3) cooling rate is quick, the casting system and the cooling system should radiate slowly. (4) shrinkage is big, easy to have the shrink hole obviously, the distortion, the directivity (5) should pay attention to the control formation temperature, expects warm low then the directivity is obvious, the mold warm is lower than 50℃, the note leaves models a not gloss, easy to have the fusion not to be good, has the flow marking warm, the mold is higher than easy to have the warp and the distortion. (6) models a wall thickness to have to be even, avoids the gap, the acute angle. 3. polystyrene (1) amorphic substance plastic, the water absorbability is small, not easy to decompose, the natural crisp easy crack, the thermal-expansion coefficient to be big, easy to have the internal stress side, (2) fluidity is good, overflows the value is 0.03mm (3) suitably with Gao Liaowen, Gao Muwen, injects the pressure lowly, the extension injection time is advantageous in reduces the internal stress, prevents the shrink hole and the distortion (4) may use each form the runner, the runner with models an attachment point to be supposed to transit smoothly. (5) models a wall thickness to be supposed to be even, has not suitably inlays, the gap, the acute angle, each should transit smoothly. The 4.ABS (1) amorphic substance plastic, water absorbant, wants the thorough drying (2) fluidity medium side, overflows the value is 0.04mm (3) with Gao Liaowen, Gao Muwen, the injection pressure also is suitably high (4) mold casting system to have to be small to the material resistance to flow strength, should pay attention to the choice runner the position and the form, the drawing of patterns ascent for 2° above. 5. plexiglass (1) amorphic substance plastic, the water absorbability is big, not easy to decompose, the nature is crisp, skin hardness low (2) fluidity medium side, overflows the value is 0.03mm (3) suitably with the high-pressured injection, and uses high material temperate Gao Muwen, may increase the fluidity, reduces the internal stress, reduces the directivity, the improvement transparency and the intensity. (4) mold casting system wants small to the material resistance to flow strength, the drawing of patterns ascent to be supposed the big 6. nylon (1) crystalline plastic, the water absorbability to be big side, easy to decompose (2) fluidity to be extremely good, overflows the value is the 0.02mm (3) shrinkage is big, the directivity is obvious, easy to have the shrink hole and the distortion (4) should pay attention controls the pattern making warm, otherwise and models a performance to the crystallinity influential (5) to be possible to use each form the runner, the runner with models an attachment point to have the smooth transition, the flow channel and runner section size big good, favors takes shape (6) models a wall thickness not to be suitable too thick, and should be even 7. metaformaldehyde (1) crystalline plastic, the water absorbability is small, extremely easy to decompose (2) fluidity medium side, overflows the value is 0.04mm, the fluidity to injects the pressure variation to be extremely sensitive (3) crystallinity to be high, when crystallization the change in volume is big, the shrinkage big (4) mold should heat up, the mold temperature is high, and pays attention controls the pattern making correctly warm, guaranteed models a quality, the spray nozzle should alone heat up, and suitable control spray nozzle temperature. (5) mold casting system must be small to the material resistance to flow strength, the runner section takes big suitably, avoids the dead angle accumulating material 8. to gather the carbonic ether (1) amorphic substance plastic, the water absorbability is small, not easy to decompose side, (2) fluidity is bad, overflows the value is 0.06mm, the fluidity is very sensitive to the temperature change (3) formation shrinkage to be small, models the precision high (4) mold to be supposed to heat up, the mold heats to models the quality influence to be big, should control the pattern making warm (5) fusing temperature to be high correctly, the viscosity is big, the cooling rate is quick, the mold casting system should take thick, short as a principle, and supposes the cold slug well suitably, uses the direct runner (5) fusing temperature is high, the viscosity is big, the cooling rate is quick, the mold casting system should take thick, short as a principle, and supposes the cold slug well suitably, uses the direct runner (6) models a wall not to be suitable too thick, should be even, avoids having the acute angle, the gap 9. gathers the sulphone (1) amorphic substance plastic, the water absorbant big (2) fluidity is bad, is sensitive to the temperature change, the cooling rate is quick (3) formation temperature is high, takes shape suitably with the high pressure.The hypotonia models a surface easy to produce the ripple, the air bubble and the dent, the pressure excessively is high, then the drawing of patterns is difficult. (4) mold must heat up, the mold warm regards wall thickness to decide (5) mold casting system to be supposed to be thick and to be short, radiates slowly, the resistance is small, suitably with goes nonstop to -like the spray nozzle. 10. polyphenylene oxide (1) amorphic substance plastic, the water absorbability is small, easy to decompose (2) fluidity to be bad, is sensitive to the temperature change, the coagulation speed is quick, the formation contracts slightly, (3) uses the high-pressured high speed injection suitably, gu