(2) background technology:
The combination property of epoxy resin is splendid, its formula Design is versatile and flexible, epoxy resin is used widely in the field such as electric power, electronic apparatus, the particularly mould material of the electrical equipment such as electric power mutual-inductor, transformer, insulator, when epoxy resin is applied to high voltage electrical equipment, require that it has extremely low partial discharge quantity, otherwise premature aging, electric leakage will puncture even accidents caused because partial discharge quantity exceeds standard.Pore in epoxide resin material produces the main reason of shelf depreciation, therefore when poured with epoxy resin, all adopts vacuum pouring deaeration technology to reduce air gap in cast product and bubble as far as possible.
Typical technique is that the fillers such as resin, curing agent and silicon emblem powder, mill base are calculated each component weight by proportioning, and preheating 60 DEG C/3 ~ 4h in an oven in advance after weighing, its batch mixing divides firsts and seconds batch mixing.Storage tank A, the heating system of storage tank B and vacuum system is first started in secondary batch mixing.Add the resin after preheating, filler toward storage tank A again, and add the curing agent after preheating, filler in storage tank B, storage tank A whipping temp is set as 55 DEG C, stir 3 ~ 4 hours, storage tank B whipping temp is set as 50 DEG C, stir 3 ~ 4 hours.Then vacuumize stirring to storage tank A, storage tank B, vacuum is all set to 4mbar.After above-mentioned vacuum outgas, then in mixing tank batch mixing stir vacuumize again after batch mixing imported in pouring can pour into a mould the demoulding after curing oven heating cure again.
(3) summary of the invention:
High-viscosity epoxy resin batch mixing liquid in atmosphere, also certain gas is dissolved with, but bubble size is very little in batch mixing liquid depths, usually exist with microbubble form, the speed that microbubble relies on natural buoyancy to rise is extremely slowly, external force must be relied on to take bubble to liquid level, and therefore comparatively effective deaeration mode adopts the method such as vacuum stirring deaeration and vacuum film deaeration at present.Pressure in tank diameter increases from top to bottom successively, has occurred larger low-pressure area in middle and upper part, therefore, according to the condition of bubble formation, bubble mainly in, upper grown, to gather and deaeration.
Due to each composition material of liquid-state epoxy resin batch mixing and the different of proportioning thereof, also may due to epoxy resin, curing agent inherent quality problem, cause the gel time often criticizing batch mixing inconsistent, and the vacuum stirring deaeration process variations of the vacuum deaerator plant performance used and employing thereof is very large, therefore the technological parameter of existing vacuum stirring deaeration arranges and is mostly by rule of thumb or arranges with reference to process similarity, specific aim is poor, its setting value does not rationally change with the manufacturer of mixture recipes or material or working conditions change, affects deaeration effect and product quality.The present invention introduces a kind of epoxy resin secondary batch mixing degassing temperature mixing speed control system, for adopting the vacuum stirring deaeration of secondary mixing system technique, in secondary mixing system, storage tank A is an epoxy resin, filler batch mixing degas system, when changing epoxy resin mixture recipes or factory or redefining technological parameter when vacuumizing operating mode, it is characterized in that when changing mixture recipes or vacuumizing operating mode, storage tank A is compared in intensification and vacuum stirring de-aeration by Site Detection, the vacuum stirring deaeration effect of its batch mixing under each specified temp and set mixing speed, make it can not affect production in original system, select the temperature of the technique of vacuum stirring deaeration at ordinary times and the optimum configurations of mixing speed.
Epoxy resin raises its viscosity with temperature and declines, but when temperature rises to certain value, viscosity downward trend slows down, and is finally substantially tending towards certain numerical value, and in epoxy resin batch mixing, the more granularities of loading of filler its batch mixing viscosity thinner increases more in addition.It makes epoxy resin temperature, viscosity corresponding relation to the skew of viscosity augment direction in batch mixing, and bubble surface tension force diminishes along with the density contrast of the two body phases adjacent with superficial layer and diminishes, therefore surface tension also declines with viscosity and reduces.After bubble rises to nearly liquid level, bubble can not be overflowed at once, but under the effect of pressure reduction, bubble continues to expand, and stay for some time under nearly liquid level, after shaking off liquid level tension force, could overflow or break, its time of staying shortens with the reduction of the viscosity of pressure, batch mixing liquid, in sum, the viscosity of bubble effusion efficiency and epoxy resin batch mixing is closely related, and epoxy resin compound viscosity relation non-linear with temperature, therefore different optimum temperature setting values is just existed for different batch mixings.
On the other hand, bubble effusion effect and mixing speed closely related, when many bubbles being in Different growth phases occur, too high mixing speed will make a part of bubble have little time to grow to break and overflow fully to be brought back again batch mixing liquid depths, too low mixing speed makes bubble take liquid level time lengthening to, and effective inclined heated plate is shortened.Due to different temperature and compound viscosity, make the number of bubbles and the speed of growth difference that are in Different growth phases, therefore mixing speed is selected different, makes the bubble being in different growing stages be transported to liquid level and is changed with the difference of temperature and viscosity by effective conevying efficiency of overflowing.
System utilizes the change of vacuum to reflect the change of bubble effusion quantity and volume in epoxy resin batch mixing, under the design temperature of a certain reflection viscosity B coefficent, by starting vavuum pump, detect vacuum and reach time of higher limit (low pressure limit value) from preset lower limit, be reflected in this mixing speed and lower deaeration efficiency be set and compare the setting for optimizing mixing speed by repeatedly production testing.Meanwhile, by closing vavuum pump, detecting vacuum reaches lower limit (upper pressure limit value) time from capping value, reflecting deaeration effect at such a temperature, compared by the detection of each temperature set-point and arrange for optimizing temperature.
Described epoxy resin secondary batch mixing degassing temperature mixing speed control system, mixing speed for storage tank A vacuum stirring de-aeration in this system controls, when the system is operated, first resin, filler are calculated each component weight by proportioning, for subsequent use after carrying out preheating and drying process in advance by former technological requirement in baking oven or hot-blast stove after weighing, then start heating system and the vacuum system of storage tank A.First epoxy resin is dropped at storage tank A, drop into again under silicon powder is cooled to top temperature and heat up, the temperature of vacuum stirring can be carried out after its top temperature and epoxy resin melting, such as start staged at 40 DEG C to about 50 DEG C to heat up, warming room is every equal, first stirring makes batch mixing evenly open vavuum pump again in 5-15 minute, vacuum is set within the scope of a bound, such as can be pressed the vacuum setting value of former technique as low pressure limit value, and get vacuum decline (pressure increase) to this low pressure limit value add 6-15% as higher limit, the pressure signal of its reflection vacuum send master controller process, its working signal opening or closing vavuum pump is sent by master controller.Master controller adopts staged heating mode, the identical warming room of about each desirable 3-8 DEG C every.The a little higher than mixing tank design temperature of its terminal temperature, requires that intensification power is large, speed is fast and evacuation rate is fast by such as 75 DEG C about-90 DEG C.The mixing speed of agitator adopts successively decreases according to described staged heating mode temperature section at different levels, the i.e. maximum temperature mixing speed that adopts former technique to determine to low lapse of temperature, and through repeatedly production effect contrast, its mixing speed at different levels and the bubble speed of effusion are adapted.
During system works, storage tank A first heats up and opens vacuum pump evacuation when making vacuum reach setting pressure lower limit and reach relevant temperature section design temperature at top temperature, close vavuum pump and valve, the drop timer timing when vacuum drops to setting pressure higher limit starting vacuum terminates, make to open again after too much bubble is eliminated in several seconds time delay the rising timer that valve and vacuum pump evacuation start vacuum simultaneously, make vacuum reach the timing of setting pressure lower limit to terminate to enter next section, so go round and begin again, sequentially record the drop timer of each vacuum and the timing time of rising timer, its rising timer reflection mixing speed arranges the impact on vacuumizing performance, the rising timer timing time length of more each vacuum, reflect the vacuum stirring deaeration efficiency of its design temperature point, determine its mixing speed thus mixing speed under obtaining each temperature-viscosity, its drop timer reflection system is at each temperature section bubble formation speed, the drop timer timing time of the more each vacuum of deduction vaccum leakage rate impact reflects deaeration effect, the inclined heated plate that can be allowed by technique as required, revise bubble removal step temperature range and top temperature that former technique determines and terminal temperature is arranged to increase and decrease the pumpdown time, again the set temperature section of examination temperature and mixing speed combines and the scheme of running time, its running time, the inclined heated plate according to deaeration effect and permission was arranged, then to reach final vacuum choose its drop timer timing time relatively long corresponding to temperature section, as the temperature of producing at ordinary times and mixing speed setting value temperature-constant operation, if desired according to vacuumizing elapsed time, work consumes, energy consumption, through multiple described temperature and mixing speed setting value more also can be chosen, namely all the other temperature sections proceed to next temperature section after being warmed up to desired temperature by the setting of its temperature and mixing speed.Otherwise the desired temperature that existing technique only establishes desired temperature usually high get the short time or, the present invention has more described selection scheme according to deaeration effect, and therefore will reach final vacuum for batch mixing has more rationally Scheme Choice accurately.Then stop heating up after terminal temperature and constant-temperature vacuum stirring deaeration under the desired temperature of former technological requirement and the activity time of permission thereof, undertaken pouring into a mould, solidifying and the demoulding by former technological requirement more afterwards, complete testing process.Finally, with PD meter, detection is put to pouring piece make-game if desired, check whether it meets relevant national standard or inner controlling standard of enterprise adjusts pumpdown time and desired temperature again.
Produce at ordinary times and do not do described detection, only run according to described temperature and the mixing speed plan of establishment, all the other are all by former technological requirement operation.