CN1138505A - Clearence jet moulding and moulding auxiliary implement for large casting cold and hard casing (core) - Google Patents

Abstract

A sand-airflow jet moulding method and its aid tool for mfg. cold and hard sand core of large casting features that the jet direction of sand and airflow is parallel to surface of mould or internal surface of core box. Before moulding, a "moulding aid tool" is installed to working appts. to form a "gap-type impression" between it and mould surface or internal surface of core box. A small-bore nozzle is inserted in it for jet moulding. Furan resin sand is used to increase quality of casting.

Description

The clearance type jet molding method of arenaceous shell type that heavy castings are chill (shell core) and moulding accessory

The present invention relates to the manufacture technology and the moulding accessory thereof of a kind of large-scale chill arenaceous shell type (shell core).

Heavy castings are one of key technologies in the major technologies and equipment development.As " the nineties mechanical industry key technology " book point out: the large-scale workpiece manufacturing is the key in the major technologies and equipment development.Major technologies and equipments such as " Three Gorges Projects ", " subcritical and supercritical thermal power generating set ", " Baosteel the third stage of the project ", " 900MW level nuclear power station ", manufacturing technology and quality to crucial large-scale workpiece are had higher requirement, thereby, the large-scale workpiece manufacturing technology must be given first research, goes ahead of the rest.Because big manufacturing technology of China falls behind, and causes production efficiency low, the energy and raw materials consumption are big.Round and plump as the large-scale steel-casting blank is universal phenomenon, large-scale steel-casting blank allowance more than hundred tons can reach more than 100 millimeters, if scrap the forging of 200 tons of steel ingots, its direct economic loss will be more than 1,500,000 yuan, therefore improve the large-scale workpiece manufacturing technology level, reducing consuming, is the important channel of improving China's engineering goods market competitiveness.Come across the organic chemistry self-hardening sand of the seventies, can significantly improve casting quality as furan resin-sand with it, reduce labour intensity, investment cost is lower, replaced early stage clay-bonded sand, oil-sand, water mud sand, water-glass sand and hot box resin sand abroad in a large number, moulding and core manufacturing craft are taken on a new look.External heavy castings quality why can be than being better of China, and its one of the main reasons just is this.This point is known by the relevant ministries and commissions of China already, thereby once calls heavy castings manufacturer to adopt furan resin-sand again and again in the eighties, and the All-China Federation of Trade Unions has also set up with the popularization group headed by comrade Wang Chonglun.Yet, the effect of promoting is unsatisfactory, even to this day China adopts the producer of Furan Resin-Bonded Sand heavy castings still as wind hair rare thing, trace it to its cause, mainly be because China's chemical industry technical merit is lower, homemade furane resins cost an arm and a leg, and the producer's economic benefit that adopts the Furan Resin-Bonded Sand heavy castings is descended.So Chinese large-sized castings production producer is among the awkward contradiction; Adopt the furan resin-sand casting quality economic benefit that is improved to descend; Do not adopt and casting quality is not high, make China's major technologies and equipment quality influenced.One of the two must be true.The jet molding method researcher is very few both at home and abroad, may have only me adhering at home.Some patents have been applied in Japan, the German eighties, have understood that belong to vertical gunite entirely, promptly the sand air-flow of Pen Sheing is vertical with model surface according to me.This is not the optimum Working of jet molding method, causes sand mold compactability not high, and work situation is bad, and also difficulty obtains bigger economic benefit simultaneously.

In addition, the Chinese large-sized castings production, how with water mud sand or sodium silicate molding coremaking, working condition is extremely arduous.Fat sand mold as hard as flint is difficult to rout during shake out.Be used in the waterglass the inside abroad and add defeated and dispersed dose method head it off, though China drops into very big manpower and materials but still is unresolved on this problem.Developing the mechanized production apparatus of large-scale sand mold and core, always is the long-standing problem of casting industry.

The present invention seeks to propose the clearance type jet molding method and the moulding accessory of the chill arenaceous shell types of a kind of heavy castings (shell core).Both adopt chilled furan resin sand or other chemical self-hardening sand to reach, improve casting quality, reduce sand mold cost and energy resource consumption simultaneously again.

Elaborate content of the present invention below, principal character of the present invention is that sand air-flow injection direction is parallel to model surface or is parallel to the inner surface of core box.In order to realize this injection molding method, before moulding, must manufacture " moulding accessory " according to the characteristics of model and core box, then they are installed in the sandbox, on the template or in the core box, make it to constitute " clearance type die cavity ", insert with small-bore spray gun again and wherein spray filling with model surface or core box inner surface.The moulding accessory can have various ways, but mainly is following three kinds:

First kind of form is " special floor sand layer ".General floor sand layer is provided with for the facing sand layer of conserve expensive, promptly sand mold is divided into expensive facing sand layer and more cheap floor sand layer two parts, thereby reduces the sand mold price, increases economic efficiency.Floor sand layer of the present invention is in order to constitute the clearance type die cavity with model surface, to be provided with in order to spraying thin-shell type facing sand layer, also being provided with in order to save the floor sand layer in a large number simultaneously.Be characterized in that it is nonexpondable, i.e. so-called " nonvolatil ", thereby contain more binding agent in its molding mixture, so that have higher intensity, guarantee repeatedly to use.Disassembling case band is installed in addition, in order to avoid the floor sand layer comes off when repeatedly using between this floor sand layer and sandbox.Removable case band has various ways according to the shape of floor sand layer, its topmost characteristics are: the one end stretches into inner and firm the combining of floor sand layer of floor sand layer, nut (or bolt) is arranged on the other end, tighten together by bolt outside sandbox (or nut) and sandbox.After the completion of castings production task, when the floor sand layer need be laid, outside sandbox, unload this case band of bolt (or nut) and promptly lose fastening usefulness.

Second kind of form is " special arbor ", its external surface shape of this arbor is similar to the core box inner surface configuration, cylinder iron cast or steel plate is welded into, its characteristics are that when being positioned in the core box it and core box inner surface constitute a clearance type die cavity to it.For the large-scale core of manufacturing with this law, may be too thin because of the furans layer of sand, inner iron and steel arbor is again one " rigid body ", and the contraction of restriction foundry goods may cause heavy castings to produce hot tearing.Can make this arbor flexible in this case.Now with large ingot mould elasticity arbor it is described: its structure is made up of arbor body (1), elastic layer (2) and appearance housing (3) as shown in Figure 1.Arbor body (1) can be that ironcasting or steel plate are welded into.To be that waste and old steel plate is overlapping form elastic layer (2), and appearance housing (3) is made by steel plate.The three is installed together by bolt, wherein bolt (4), loose piece (5), slotted hole (6).Outside this arbor, spray one deck furan resin-sand during coremaking, after the casting when foundry goods shrinks, the pressure that furans layer of sand and arbor are shunk simultaneously, the elastic layer in layer of sand and the arbor (2) all can " be made a concession ".Thereby reduced the possibility of foundry goods formation fire check.

The third form is " a backup plate accessory ".To some complex-shaped heavy castings, if adopt " the special arbor " of second kind of form, then arbor is difficult to take out during shake out, can adopt the third form moulding accessory---" backup plate accessory ", and it and core box and spray gun combine and can produce the hollow sand cores of no iron and steel arbor.The backup plate accessory is with nail, wooden unit, Pressure sensitive adhesive tape etc. 5～10 layers of glued board to be formed a hollow box body, its external surface shape is similar to the core box inner surface configuration, it can constitute four sides clearance type die cavity with surface within the core box when being positioned at it in the core box, sees Fig. 2.Coremaking plate (7) among the figure, core box (8), backup plate accessory (9).When these clearance type die cavities being filled up with spray gun, the horizontal backup plate accessory of installation shown in Figure 3 for another example (10), coremaking plate (11) wherein, core box (12), backup plate accessory (13), furans core vertical wall (14), cushion block (15), cushion block (16).After the horizontal wall of injection furane resins core vertical on the horizontal backup plate accessory, just obtain hollow furans core.

Good effect of the present invention is: save molding sand 60～80% than prior art, casting mold need not toast, and can save a large amount of energy and large-scale roasting plant, the shake out operation becomes simple, saved man-hour, shortened the production cycle, cast(ing) surface fineness and accuracy are greatly improved.

Fig. 1 is the principle assumption diagram of special arbor among the present invention

Fig. 2 is the principle assumption diagram of backup plate accessory among the present invention

Fig. 3 is an operation principle schematic diagram of the present invention

Fig. 4 is the work schematic diagram of existing turbine blade horizontal type shaping method

Fig. 5 is the work schematic diagram of the existing vertical molding of turbine blade

Fig. 6 is the operation principle schematic diagram of turbine blade described in the embodiment of the invention 1

Fig. 7 is the A-A profile of Fig. 6

Fig. 8 is the following sand mold model structure figure of the embodiment of the invention 2

Fig. 9 is the last sand mold model structure figure of the embodiment of the invention 2

Figure 10 is the modeling process schematic diagram of 2 times sand molds of the embodiment of the invention

Figure 11 is the modeling process schematic diagram of sand mold on the embodiment of the invention 2

Figure 12 is the embodiment of the invention 2 sand mold assembly drawings

Figure 13 is the assembling assumption diagram of the embodiment of the invention 3 arbors and core box

Figure 14 is the assembling schematic diagram of the embodiment of the invention 4 core boxes and arbor

Embodiment 1: the clearance type jet molding method of large-scale Kaplan turbine blade furan resin-sand shell mould, and former process using water-glass sand hand moulding has two kinds of forms promptly: horizontal and vertical, as Fig. 4 and shown in Figure 5.With manpower molding sand is successively filled consolidation in sandbox, two kinds of technology molding sand consumptions equate, are assumed to be 50 tons, (maximum Kaplan turbine blade is the Ge Zhou Ba turbine blade, and its molding sand consumption is 165 tons).Template above Fig. 4 (17), model (18), sand mold (19), template above Fig. 5 (20), model (21), sand mold (22).If when adopting clearance type jet molding method of the present invention to produce the Kaplan turbine blade, needn't upgrade frock, still can adopt former frock.Its " moulding accessory " floor sand layer for making in advance, as shown in Figure 6.At model (23), floor sand layer " clearance type die cavity " (25) are arranged between (24).Wherein spray filling with small-bore spray gun (26) insertion during moulding, moulding is promptly accused and is finished after waiting to fill up.[floor sand layer (24) to manufacture process as follows: before injection molding, certain thickness extra play is installed on the surface of model (23) for example can adopts soft sheet materials such as thick rubber slab, the simplest extra play is to lay out one deck common brick, the maximum surface of common brick is attached on the surface of model (23), carry out on the surface of common brick then that water-glass sand is manual fills moulding, promptly get floor sand layer (24) after filling up curing].

After matched moulds sprays, the shake out operation becomes simple, because have the facing sand series of strata shell shape furane resins layer of sand of 10% volume ratio, has good collapsibility, defeated and dispersed already under the effect of high-temperature molten steel, and the floor sand layer (24) with 90% volume ratio is that water-glass sand is made, and its collapsibility is bad, and also promptly casting back sand mold still has very high intensity.Like this, when shake out, unpack and take out foundry goods, the facing sand layer is defeated and dispersed naturally to be fallen, and floor sand layer (24) still can remain intact.Because of its not only intensity height but also do not contact molten steel.Whether the floor sand layer can remain intact when shake out or be more intact is the key of this technology success or not, thus when manufacturing the floor sand layer, to take reinforcement measure as: 1. making and adding more binding agent such as waterglass or cement etc. in the material of floor sand layer (24).2. on its sandbox except original case band, add disassembling case band again, shown in they (27) among Fig. 7 and (28), in fact they are two rod irons, its length is slightly less than sandbox inner surface spacing, two ends link together by two nut straight couplings (32) and sandbox, in case the floor sand layer splits away off from sandbox when shake out.But to this batch foundry goods all produce and finish, in the time of need laying the floor sand layer, earlier nut straight coupling (32) is backed out, then this disassembling case band (27), (28), just lost usefulness, do not hinder taking off of floor sand layer.Be welded with little rod iron (30) and (29) on it and be in order to prevent that this case band from installing and to rotate during dismounting.Be welded with Russian П font reinforcing bar (31) on the nut straight coupling (32), so that rotate this nut straight coupling (32).

Embodiment 2: the marine propeller moulding is very complicated technology, equals to use simple tools---auxiliary " engraving " down of scraper plate goes out sand mold, and the production cycle is long, and teams and groups (about 10 people) produce a ton screw with 20 days ability.This technology is greatly simplified the screw production process.But because the shape of marine propeller is as a large-scale electric fan, its mould and modeling process all are different from general foundry goods, and Fig. 8 is the pressure face model, promptly descends box model.Fig. 9 is the suction surface model that is goes up box model.

The process of making mo(u)ld bottom half as shown in figure 10.At first pressure model (Fig. 8), be positioned on the supporting plate (it is equivalent to nowel) then to form the clearance type die cavity between supporting plate and model.Base plate (33) wherein, pressure face model 34, supporting plate 35, location key seat 36, with spray gun to wherein filling up furan resin-sand, treat that 20 minutes resin sand solidifies after, take off model, this sand mold is promptly accused and is finished.Filled required time only 3 minutes.On its excess-three supporting plate, repeat above-mentioned moulding operation again.Following sand mold is promptly accused and is finished.

Make the mo(u)ld top half process as shown in figure 11, the top box that has the floor sand layer is combined on the suction surface model (Fig. 9) by the location case number (CN).Then form the clearance type die cavity between the floor sand layer of top box and following model, wherein: top box 37, suction surface model 38, location key seat 39, with spray gun to wherein filling up furans sand, treat that 20 minutes resin sand solidifies after, take off sand mold, this sand mold is promptly accused and is finished, and it is 3 minutes that filling takes time.Repeat above operation again, just can produce all the other 3 sand molds.Pass through mould assembling then, must be just again center oar shell sand mold is carried out as the screw sand mold mould assembling figure of Figure 12.

Embodiment 3: the clearance type of ingot mould is chill arenaceous shell core sprays core production method.Its clearance type die cavity is to be made of former technology core box and special arbor, as shown in figure 13, and wherein: base (40), core box (41), special arbor (42), guiding awl (43), water conservancy diversion frame (44).Special arbor (42) is for welded steel plate forms, and the clearance type die cavity mean breadth between it and the core box is 30mm, above width be 40mm, below width be 20mm.China Golconda steel mill introduces Japanese Nippon Steel ingot mould furan resin-sand and catches and hit molding, and its sand layer thickness is 80mm, and the utility model is over half than saving molding sand.

Embodiment 4: large-scale cast iron pipe fittings (bore Φ 700mm, threeway, elbow, four-way etc.) clearance type spray core production method (molding).Its clearance type die cavity is to be made of former technology core box and special arbor.Now be that example illustrates it with three links: Figure 14 is core box and special arbor formation clearance type die cavity schematic diagram, wherein the opposite opened core box 45, arbor 46 clearance type die cavities 47, cushion block 48, spray gun 49, tamper 50, during coremaking such as Figure 14 with arbor 46, be fixed on down on the core box with cushion block 48, and (its role is to die cavity is decomposed three direct projection consolidation districts by putting tamper 50 well, guarantee to spray the degree of packing) lift core box, promptly available spray gun and spray and filled.

Claims (4)

1, the clearance type jet molding method of the chill arenaceous shell types of a kind of heavy castings (shell core), it is characterized in that: before moulding, manufacture the moulding accessory according to the characteristics of model and core box, then the handle modeling accessory be installed in the sandbox or core box in, make it to constitute " clearance type die cavity ", insert with small-bore spray gun again and wherein spray filling with model surface or core box inner surface.

2, a kind of moulding accessory that is applicable to the clearance type injection molding of the chill arenaceous shell types of heavy castings (shell core), it is characterized in that: the moulding accessory has three kinds of forms, and 1. the floor sand layer is in the sandbox, combines securely by case band and auxiliary tank band and sandbox.2. the inner surface of the outer surface of arbor and core box is similar, form between the two the clearance type die cavity 3. the backup plate accessory be to use nail, wooden unit, Pressure sensitive adhesive tape are formed a hollow box body to 5-10 layer glued board, its external surface shape is similar to the core box inner surface configuration, and when being positioned at it in the core box, it can constitute the clearance type die cavity with the core box inner surface.

3, moulding accessory according to claim 2, it is characterized in that: the moulding accessory also can be installed on the template or in the core box.

4, moulding accessory according to claim 2 is characterized in that: its auxiliary tank band with bolted on sandbox.

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