CN1762677A - Sequential coagulation method for casting coil - Google Patents

Abstract

The invention discloses a sequent gelatin method of resin casting coil, which is characterized by the following: casting the resin in the moulding chamber; finishing the gelatin course according to the sequence; positioning the prior injection through gelatin. The invention eliminates the internal stress due to solidifying contraction of resin casting material, which shortens the coil shaped period and manufacturing cost.

Description

The gel method in regular turn of molded coil

Technical field under the present invention:

The present invention relates to a kind of gel method of resin-cast material, especially be applied in the gel method of the resin-cast material in the coil pouring forming technology of large-scale electrical equipment (for example power transformer and power reactor).

Gel: be have reactivity the resin-cast material under certain temperature condition, become solid-state process of setting from liquid state.Notice that the end of solidifying and do not mean that chemical reaction that the resin-cast material loses flowability is so the back curing that often need carry out behind the gel is handled.

Technical background of the present invention:

Set forth for convenient, this paper is example with the resin gel method of the moulding by casting of resin-insulated dry power transformer coil.

The moulding by casting mode of existing transformer coil has two kinds of patterns, and a kind of is " conductor+fiber glass reinforcement " that soaks into full filling in the die cavity with pure resin-cast material saturation, and this pouring piece does not have macroscopical cavity to exist before cast in the die cavity; Another kind is " conductor+insulation location skeleton " with non-full filling in the resin-cast material embedding die cavity of band powder filler, has macroscopical cavity to exist in the die cavity before this pouring piece cast.

The technology of existing poured with epoxy resin formed coil is to realize by such trilogy :+the second step of first step cast gel+the 3rd step solidifies.Specific descriptions are, at first preheating and dry openpore coil, under certain temperature condition, under vacuum environment, pour into a mould the openpore coil then, resin-cast material (resin-cast material: by resin, curing agent, promoter, materials such as powder filler are according to specific formula components and ratio, what form through being mixed has a reactivity, the compound that is used for pouring technology) temperature and pouring piece (pouring piece: by resin pickup not in cast unit that goods coil and matching die assemble) temperature is basic identical, requires the resin-cast material to remain good mobile permeability in this casting process; Transfer to then solidify in the baker long-time in resin-cast material in the warm gel coil; After gel is finished, be warmed up to higher temperature again the resin-cast material is solidified fully; Cooling back form removal, finishing coil are finished the moulding of molded coil.

The gel method of this casting resin, owing to gel in the even temperature field, the resin-cast material at each position of pouring piece is according to identical reaction process gel, so we are referred to as " balanced gel " method.

The problem that balanced gel method exists is:

1. the resin-cast material changes the volume contraction of the solid-state 5%-10% of having into from liquid state after by the chemical reaction gel solidification, this contraction brings two kinds of potential defectives to coil, the one,, the constraint of the interface of various materials causes this Volume Changes to be distributed in coil inside with the form of strain in the coil, this distribution is not necessarily uniform, so just there is very big internal stress in portion in coil, even stress occurs and concentrate, this internal stress can cause the cracking of coil or because the existence of the underbead crack that internal stress produces causes coil generation shelf depreciation; The 2nd,, when various materials in the coil are unbalanced to the interface constraint process unbalanced or gel reaction of resin, this Volume Changes can be converted into the directional migration of resin along the part that certain direction takes place again, when not having unnecessary resin-cast material can freely flow, in time compensate the vacancy that this migration forms, just form shrink defects, as coil surface depression, bubble, flake etc. appear, this defective needs repairing afterwards to handle, repair to handle and to bring other new problems again, as Insulation Problems or appearance quality.

2. backward gelatin phenomenon.Suppose that the cast liquid level is that steady weighing apparatus ground advances from bottom to top in die cavity, so, the resin-cast material of going into to annotate need axially pass through the top that all insulation filling materials could arrive coil in early days, mobile distance is very long, the time of sustained response is also just very long, and heat exchange is fullest also, so temperature is also the highest, exothermic heat of reaction is aggravated the growth rate of resin-cast material viscosity again, passes the obstacle of infiltration forward so become the resin-cast material of later stage injection; On the contrary, the resin-cast material that the later stage goes into to annotate is fresh, viscosity is low, mobile distance is very short, and the reaction time is also the shortest, make its gel need extra time-delay.Thereby the phenomenon of pouring piece top than the more first gel in bottom occur, this paper is referred to as " backward gel ", and this is not desirable gel process.Its shortcoming of bringing is exactly that the cast of the later stage of cast is difficult more, even the cast failure occurs.

For solving the influence of above-mentioned two kinds of unfavorable factors, the way of existing balanced gel is exactly, at first be suppress casting process significantly water the material feeding reactivity, secondly be for a long time in temperature gel at a slow speed.

Technical task of the present invention:

The volume contraction of resin-cast material gel reaction process is intrinsic, and the present invention is devoted to solve the defective of being brought because of the resin-cast material volume contraction that forms in the gel process, is devoted to shorten the molding cycle of molded coil.

Technical scheme of the present invention and forming method:

The present invention proposes the technical conceive of " gel in regular turn ", by gel in regular turn, the volume contraction that makes the resin-cast material is according to the acquisition compensation progressively, pointwise of the sequencing of the time of cast, thereby avoided the strain of resin-cast material volume contraction portion's formation in coil residual, so the described defective of balanced gel method can not occur.The casting process and the gel process of coil unite two into one.

Gel in regular turn: carry out gel in proper order according to the time order and function that is poured into the resin-cast material in the die cavity exactly, pioneer elder generation gel.Because the gravity effect, the resin-cast material of going into to annotate must be deposited on the bottom of coil earlier, by gel it is fixed, and so just presents directed gelatin phenomenon from bottom to top in watering injection cavities simultaneously.

Realize that this gel is not difficult in proper order, as long as the cast materials flow road of pouring piece is provided, by design resin-cast material formula and gelling temp, the gelation rate of adjusting the resin-cast material is complementary with the rate of climb of pouring into a mould liquid level and gets final product.

Below in conjunction with concrete feature and the embodiment of setting forth the gel method in regular turn that the present invention relates to of the cast embodiment of transformer coil.The casting forming method of other electrical equipment members similarly.

Fig. 1-1～Fig. 1-the 4th, the schematic diagram of the gel process in regular turn full loading mould cavity of glass fibre, when coil is uprightly poured into a mould.

Fig. 2-1～Fig. 2-the 3rd, the pouring piece package assembly schematic diagram full loading mould cavity of glass fibre, when coil is uprightly poured into a mould, Fig. 2-1～Fig. 2-3 is respectively front view, vertical view and partial enlarged view.

Fig. 3-1～Fig. 3-the 4th, the schematic diagram of gel process in regular turn when the band filler coil of insulation location skeleton supportive conductors is uprightly poured into a mould.

Among Fig. 1-1～Fig. 1-4 and Fig. 2-1～Fig. 2-3,1-internal mold, 2-external mold, the 3-gate spool, the 4-sprue gate, 5-bed die, 6-conductor (or inserts), 7-glass fibre inserts, the cast materials flow road of 8-vertical, the initial cast of 9-water the material feeding part, 10-pours into a mould subsequently waters the material feeding part, the up-to-date cast of 11-water material feeding part, 15-air channel template.

Among Fig. 3-1～Fig. 3-4,1-internal mold, 2-external mold, 3-gate spool, the 4-sprue gate, the 5-bed die, 6-conductor (or inserts), the band filler of the initial cast of 12-waters the material feeding part, the band filler that 13-pours into a mould subsequently waters the material feeding part, and the band filler of 14 up-to-date cast waters the material feeding part, 17-insulation location skeleton.

At first set forth the principle of gel in regular turn of the casting process of the loop construction that waters the full filling of injection cavities " conductor+glass fibre ".

Provide no air channel template, the pouring piece package assembly schematic diagram when the full filled type high-tension coil of glass fibre is uprightly poured into a mould among Fig. 1-1, in this pouring piece die cavity except that winding conductor (6) the full glass fibre inserts (7) of having filled, the cast materials flow road (8) of several verticals extensions is arranged on the internal mold surface.These runners and sprue gate (4) are communicated with.

Among Fig. 1-2, enter of cast materials flow road (8) the upwards walking of the resin-cast material of die cavity by vertical by sprue gate (4) cast from gate spool (3), and liquid level is risen, meanwhile, under the pressure effect of liquid level difference, resin-cast material along continuous straight runs scattering and permeating, distance as shown by arrows.This is actually the synthetic of two translational speeds.And resin has only the infiltration translational speed of a direction from bottom to top in the balanced pouring procedure.

Fig. 1-2 illustrates the permeable areas that three different cast constantly enter the resin-cast material of coil in Fig. 1-4, certainly, actual infiltration and gel process be continuously progressive, be not phase step type intermittently, so the line of demarcation among the figure does not exist.According to the cast process of Fig. 1-2 to Fig. 1-4, the resin-cast material that is penetrated in coil glass mat/band begins reaction gradually, and viscosity increases gradually until becoming gel state, and is just no longer mobile behind the gel.Arrow indicates mobile, the infiltration direction of resin-cast material among the figure.Notice herein, the material feeding part (9) of watering of initial cast is trapped in the zone, home position, from Fig. 1-2 carry out the transition to Fig. 1-4 o'clock should the zone the resin-cast material finished gel reaction, watering material feeding just no longer is moved, the also corresponding end of volume contraction effect, with the material feeding of watering of watering the cast subsequently of adjoining in material feeding part (9) zone of initial cast partly gel reaction is taking place (10) zone, viscosity progressively increases, and volume contraction appears, material feeding part (11) zone of watering of the up-to-date cast that the watering of cast subsequently adjoined in material feeding part (10) zone has just been gone into to annotate and has been penetrated into coil, up-to-date cast water material feeding part (11) because and pouring piece generation heat exchange, temperature further raises, thereby kept high mobile permeability, like this, the just gel feature (the directed gel feature from bottom to top on the presentation space among Fig. 1-4 simultaneously) gradually in regular turn on the formation time of-4 processes from Fig. 1-1 to Fig. 1.In this process, the volume contraction direction of resin-cast material gel reaction is inevitable also to be the direction that gel gradient exists, top forward's liquid level has kept fresh resin to water the high fluidity that material feeding possesses because the gel, thickening of material feeding watered in the bottom, so the cohesive force during gel makes the volume vacancy that the following volume contraction of the automatic backfill compensation of material feeding produces of watering of forward's liquid level.Because the internal stress that the gel process volume contraction causes has thoroughly been eliminated in the existence of this effect of covering continuously in casting process.The core contribution of gel method in regular turn that Here it is.Gel is exactly to go into the sequencing of injection cavities and gel according to the resin-cast material in regular turn, pioneer elder generation gel location.

Why can form gel in regular turn? answer is very simple, is exactly by artificial control, make go into injection cavities earlier water material feeding than afterwards the gel reaction of generation in advance, the speed degree of this gel reaction depends on the reactivity of watering material feeding temperature of living in and watering material feeding.So, in the control of cast/gel process, temperature and two design freedoms of reactivity are arranged.

Compare with existing balanced placing, the maximum difference that exists on the pouring piece structure is, have cast materials flow road in regular turn in the gel method, resin-cast material in the runner is that initially be mixed, fresh, the low viscous material feeding of watering all the time, in case and horizontal permeation in the coil glass fibre after, along with continuity, the resin-cast material viscosity of gel reaction process is just no longer mobile after being increased to a certain degree, so just deposition is fixed up.And in traditional balanced pouring procedure, do not pour into a mould the notion in materials flow road, it is that the depended on pressure infiltration is finished that the forward who waters material feeding advances, and flow process from bottom to top is very long, penetration length equals coil height, even reach more than the 1000mm, so, to water material feeding good penetration coil and finish the cast embedding in order to guarantee in the balanced pouring procedure, is not wish that gel reaction is arranged at casting process, otherwise, the viscosity increase of watering material feeding along with early stage injection coil, pour into a mould more and more difficult, so pouring defect occurs, even cast failure.But in regular turn during gel, the resin-cast material only permeates the radial thickness that coil is sealed, its distance generally is no more than 30mm, so the flow process of resin-cast material along continuous straight runs (be coil radially) infiltration diffusion is shorter, and the viscosity of fresh resin-cast material is very low, so, be very easy to diffusion and infiltration (but the interlayer dielectic that it may be noted that coil here must be the material that the resin-cast material penetrates easily, as the glass strap that generally uses and polyester non-woven fabric etc.).Compare, the coil of gel soaks into than the easier cast of the coil of balanced gel in regular turn.

But gel method requires slowly to pour into a mould evenly in regular turn, and the speed that makes liquid level rise must be coordinated mutually with the speed of resin-cast material radial penetration.Poring rate is slow more, and the gradient of watering the preceding sharp side that material feeding soak into to advance is more little, and the osmotic pressure that comes from liquid level difference of certainly coming is also more little and be unfavorable for infiltration.On the contrary, pour into a mould too soon, can make the resin-cast material have little time horizontal permeation and directly along cast materials flow road roof fall, this does not wish to occur.So poring rate must be controlled well.Can watch by transparent gate spool (3) and to be tending towards pressure balanced liquid level, thereby in time adjust the speed of cast blowing.Desirable cast is to pour into a mould evenly, such as, complete embedding coil needs 120kg resin-cast material, design 2 hours and finish cast, dispensing speed when then at the uniform velocity pouring into a mould is 1kg/min, if the high 1200mm of this coil, the normal speed of resin-cast feed liquid position rising is 10mm/min so.If the speed of resin-cast material infiltration glass fibre is 5mm/min, the thickness of sealing of the 30mm of horizontal permeation coil needs 6min (and infiltration 1000mm highly needs 200min in the balanced gel), (suppose 80 ℃) so under this pouring temperature, acceptable gel time can be near 20min.When finding the above-mentioned velocity anomaly of liquid level, expression seepage velocity and poring rate are inharmonious.In addition, should determine that the open time of watering and the design of every coil in same batch the stove coil control separately poring rate according to the principle of same cast finish-time.

The bottom at die cavity is preferably opened at the sprue gate, and like this, the resin-cast material in runner can not draw the not runner glass fiber material on every side of permeable areas of the portion of catching, and avoids blocking the horizontal permeation that waters material feeding in cast process later stage.

In addition, the way of can equivalent substitution opening the casting resin runner with the way of vertical lay preimpregnated glass fibre grid grizzly bar or insulation rod at die surface.This method is very practical, but will forever consume this special material.

Keeping cast materials flow road unimpeded is controlling unit important in the casting process.Resin-cast material in these runners is because the mobile metathesis of weeding out the old and bring forth the new when at the uniform velocity pouring into a mould, and the resin-cast material that flows in the runner is to cast materials flow road (8) absorbing and cooling temperature effect on every side, so in the runner gelatin phenomenon in regular turn can not appear, and can be not blocked.Because coil has been poured into a mould the gel in regular turn of permeable areas, so the runner wall that in early days can infiltration resin waters material feeding progressively loses penetrating power, so, cast materials flow road progressively develops from bottom to top becomes the inner cast pipeline that extends of workpiece, does not have gelatin phenomenon in regular turn in runner.

Among Fig. 2-1～Fig. 2-3, illustrate the pouring piece package assembly of sealing coil in band air channel more.The setting and the distribution in vertical cast materials flow road have been illustrated among the figure emphatically.Can each inboard of sealing, the outside or both sides cast materials flow road (8) be set at coil.So, can be according to actual conditions, vertical cast materials flow road (8) is distributed between internal mold (1) outer wall that waters injection cavities, external mold (2) inwall and built-in air channel template (15) outer wall or air channel template (15), is distributed on all or part of wall of these walls.

Among Fig. 2-1, the resin-cast materials flow road distribution when illustrating air channel template (15) simultaneously and the gel gradient from bottom to top of gel formation in regular turn.Find out that equally the sprue gate is positioned at waters the injection molding lower end, the resin in runner is remaining fresh, the low viscosity state when initially being mixed.

Realize cast fast, two other important condition of gel is in regular turn: high gelling temp and the high material feeding reactivity of watering.The height notion here is for existing balanced gel method, but high to what degree, to different resin systems, different loop constructions, different casting equipments, its adaptive technological parameter is different, cannot treat different things as the same.Gelling temp and reactivity and the viscosity of watering material feeding change needs the coordinating and unifying, makes overall plans could obtain one and overlap the technological parameter of practicality.

During cast, the preheat temperature of the be mixed temperature and the pouring piece of resin-cast material can be different temperature, equilibrium temperature when gelling temp then is the two contact infiltration, the temperature of resin-cast material is not higher than the preheat temperature of pouring piece generally speaking, helps pouring practice like this.In view of this, pouring piece top be can occur and high temperature, the relatively low unbalanced Temperature Distribution phenomenon of temperature of lower kept.Even now, but the lower part temperature still wants high with respect to balanced gel method.

Summing up in regular turn the coil molding technical process of gel finishes like this:

1. become pouring piece behind the openpore coil dress mould, pouring piece is carried out preheating and (vacuum) dry processing;

2. the pouring piece temperature is adjusted and is maintained suitable value (such as 100 ℃), this pouring technology recommends to adopt static mixing technology to prepare the resin-cast material in real time, resin-cast material employing high activity prescription (is 2-10 times that balanced gel method is filled a prescription such as strengthening accelerator dosage) waters material feeding according to activity and the formula materials feature control of filling a prescription and is mixed temperature at certain suitable value (such as 60 ℃);

3. enter at the uniform velocity cast and gel program in regular turn this moment, the resin-cast material enters coil under vacuum environment after, scattering and permeating one side and coil, mould heat exchange on one side, water the material feeding temperature and obtain balance and raising (supposing to equilibrate to 80 ℃) rapidly, reaction gel and being fixed up soon, the control poring rate is kept at the uniform velocity cast/gel process until casting complete, and the time-delay certain hour makes the resin-cast material at die cavity top also finish gel;

4. shift pouring piece and carry out back curing processing to solidifying baker;

5. cooling pouring piece, form removal, the finishing coil obtains the coil finished product.

Set forth again below and water that injection cavities is left a blank, as to be with the resin-cast material cast transformer coil of powder filler principle of gel in regular turn and embodiment.

Fig. 3-1～Fig. 3-4 shows the band filler and waters the material feeding precedence diagram of gel in regular turn.Illustrate the gel order that forms among the figure from bottom to top, the band filler of initial cast waters material feeding part (12), and gel and deposition are fixed up, subsequently Jiao Zhu band filler water material feeding part (13) thus just at the gel reaction thickness that becomes, the band filler of up-to-date cast waters material feeding part (14) so just begun the mobile permeability that gel has height.Be with the maximum difference of watering injection-molded of the full loading mould cavity of glass fibre, it is upper cast, be that sprue gate (4) is above die cavity, there is not special cast materials flow road, reason is that the existence of cavity does not need special runner, but the resin-cast material must slowly flow down and deposit from level to level the top layer that is stacked in liquid level along die cavity wall.Its cast main points are slowly at the uniform velocity to pour into a mould equally, and the miscible displacement of upper and lower takes place the resin of avoiding big flow attack to cause entering die cavity.But this method still is the sequencing gel that enters die cavity according to the resin-cast material, pioneer elder generation gel.Equally, realize cast fast and in regular turn other conditions of gel also have high gelling temp and the high material feeding reactivity of watering.

Two kinds of principles of gel in regular turn of watering under the injection-molded have more than been set forth.Realize that fast the method for gel process is A in regular turn: the resin-cast material has the reactivity higher than balanced gel method, and showing as in the prescription promoter or initiator content is more than 2 times of corresponding content in the balanced gel method prescription, even up to 10 times; Perhaps B: the gelling temp of resin-cast material has the reaction temperature higher than balanced gel method, can exceed at least more than 10 ℃; Perhaps C: comprise the acting in conjunction of A and two kinds of factors of B.The gel method in regular turn that this patent is described can have than higher cast gelling temp of balanced gel method and the prescription reactivity of Geng Gao, but never is to say just must so do to be only gel in regular turn.Such as higher prescription reactivity and lower gelling temp can be realized gel in regular turn equally.

Below in regular turn the gel principle to set forth be that common state when uprightly pouring into a mould with transformer coil is that example is carried out.So-called upright cast, the short transverse that is exactly coil is a vertical.Certainly, the situation of carrying out horizontal cast is arranged also, promptly the axis direction of coil is positioned at horizontal plane.No matter the sort of mode also not necessarily is confined to transformer coil, such as reactor winding, transformer etc., the method for the gel in regular turn that the present invention sets forth all is suitable for.

Implement the effect that technical scheme of the present invention obtains:

1. eliminated resin-cast material volume contraction is brought in the balanced gel method internal stress, coil cracking, shelf depreciation, outward appearance shrink defects etc., improved the solid insulation of coil reliability, improved the casting quality of coil.

Avoid the generation of outward appearance shrink defects, also just exempted the serial problem of bringing of repairing.

2. shorten the overall molding cycle of coil, improved work efficiency

Existing balanced gel method formed coil, for realizing the excellent permeability of casting process, adopt low activity casting resin prescription, for making the gel shrink defects drop to minimum degree, warm gel in must adopting again, gel time reaches 10 hours, so just makes become unusual length of overall time of cast, gel, curing, and effect is desirable not enough.Existing actual coil gel time is 10-40 hour level, and need distribute according to the time that coil size be adjusted cast, gel, curing day part particularly.Gel method in regular turn of the present invention is then different fully, no matter band is filled out the resin material is annotated still virgin resin cast, and it has realized the unification of cast and gel process, has realized the PhastGel of no shrinkage stress, the gel method of this orientation needs to consider the size factor of coil hardly.Though in regular turn the duration of pouring of gel more longer than existing balanced gel method, gel method can be cut down the gel time of coil significantly in regular turn.Such as cast/gel time got final product in 3 hours.

3. reduction manufacturing cost

Balanced gel method is very harsh to the initial viscosity of mould material and the restriction of viscosity growth, so, material is selected to be restricted, because gel method can be poured into a mould under higher temperature in regular turn, so that the resin of thickness becomes possibility under hard resin that selectivity can be better, cost is lower or the room temperature, enlarged the use amount of filler, enlarged the selectable range of mould material, reduced the cast cost potentially or improved the pouring piece quality.

Claims (5)

1, a kind of resin-cast spare waters material feeding gel method in regular turn, it is characterized in that: be cast in the resin-cast material in the die cavity, in casting process, finish gel process simultaneously according to the sequencing of going into to annotate, the first gel of first infuser, casting process and gel process unite two into one.

2, gel method in regular turn according to claim 1, it is characterized in that: when die cavity during by the cast of the full filling of glass fibre, virgin resin, the injection molding lower end is being watered at sprue gate [4], many cast materials flow default, vertical roads [8] are arranged in the die cavity, be distributed between internal mold [1] outer wall that waters injection cavities, external mold [2] inwall and the built-in air channel mould outer wall or air channel template [15], be distributed in all or part of wall of these walls, the material feeding of watering in the casting process in the cast materials flow road [8] remains fresh low viscosity state; When the not full filled glass fiber of die cavity, the cast of band filler, sprue gate [4] are watering the injection molding upper end, and the resin-cast material flows along mould intracavity wall, does not need to be provided with cast materials flow road in the die cavity.

3, gel method in regular turn according to claim 2 is characterized in that: the cast materials flow road [8] of the vertical of moulding on the bar shaped preimpregnated glass fibre grid of vertical lay or the insulation rod equivalent substitution die surface.

4, gel method in regular turn according to claim 1, it is characterized in that: realize that fast the method for gel process is in regular turn, A: the resin-cast material has the reactivity higher than balanced gel method, showing as in the prescription promoter or initiator content is more than 2 times of corresponding content in the balanced gel method prescription, even up to 10 times; Perhaps B: the gelling temp of resin-cast material has the reaction temperature higher than balanced gel method, can exceed at least more than 10 ℃; Perhaps C: comprise the acting in conjunction of A and two kinds of factors of B.

5, gel method in regular turn according to claim 1, it is characterized in that: during cast, the temperature of resin-cast material can be different temperature with the preheat temperature of pouring piece, equilibrium temperature when gelling temp is the two contact infiltration, generally the temperature of resin-cast material is not higher than the preheat temperature of pouring piece.

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