CN103722127A

CN103722127A - Rapid investment casting method based on stereolithography (SL)

Info

Publication number: CN103722127A
Application number: CN201310754023.7A
Authority: CN
Inventors: 谈耀文; 王峰; 曹毅; 王永信
Original assignee: Shaanxi Hengtong Intelligent Machine Co Ltd
Current assignee: Wuxi Jiaoda Zengzhi Increasing Material Manufacturing Technology Research Institute Co Ltd
Priority date: 2013-12-31
Filing date: 2013-12-31
Publication date: 2014-04-16
Anticipated expiration: 2033-12-31
Also published as: CN103722127B

Abstract

The invention discloses a rapid investment casting method based on stereolithography (SL). A wax mould in investment casting is replaced with a resin prototype (1) produced by applying a 3D printing technology, the resin prototype (1) is of a thin-walled honeycomb structure, an ingate (2) is arranged on the resin prototype (1), a gating system adopts a conventional wax gating system (3), a groove (4) is formed in the wax gating system (3), the ingate (2) is inserted into the groove (4) to be bonded and fixed during tree casting, a wax rod (5) is arranged on the resin prototype (1), and vent holes are formed after shell making. The rapid investment casting method reduces the casting cost, reduces the production cycle, and avoids the cracking phenomenon of a shell in the process of roasting.

Description

A kind of rapid investment casting method based on photocuring (SL)

Technical field

The present invention relates to a kind of investment casting method, particularly a kind of rapid investment casting method based on photocuring (being stereolithography apparatus method, English: Stereo lithography Appearance, SL write a Chinese character in simplified form in English).

Background technology

3D printing technique manufacturing speed is fast, cost is low, can manufacture complex parts, and can eliminate in advance defect; Casting any metal that almost can be shaped, and be not subject to the restriction of part dimension, with low cost, but from being designed into model, model is longer its casting cycle to foundry goods.3D printing technique combines and just can maximize favourable factors and minimize unfavourable ones with conventional cast technology, makes tediously long design, modification, is designed into this process of molding again and greatly simplifies and shorten.The 3D printing technique formation Rapid Casting Technology that combines with conventional cast technology, its basic principle is to utilize 3D printing technique to manufacture directly or indirectly evaporative pattern, polyethylene mould, wax sample, template, casting mold, core or shell for casting, then in conjunction with conventional cast technique, cast out quickly metal parts.

3D printing technique based on photocuring (SL) combines with conventional full form casting process and forms the rapid investment casting based on photocuring (SL), its technical process is to utilize photocuring (SL) colophony prototype to replace the wax-pattern in model casting, be coated with refractory material thereon and form casting shell, high-temperature roasting is removed colophony prototype burning, last smelting and pouring, thus realize the object that shortens the production cycle and reduce costs.

Rapid investment casting based on photocuring (SL) does not need to press wax-pattern tool, the cycle that foundry goods obtains shortens greatly, in trial production of new products, in Single unit job lot production, have broad application prospects, but because 3D printing technique is also just at the early-stage in casting application aspect, specifically apply also in development, need constantly to grope in practice, still there is no at present relatively complete standard or technique, particularly the rapid investment casting based on photocuring (SL) is cast shell and is easily ftractureed in roasting, sl prototype use cost is higher, the problem such as troublesome poeration in production operation, the serious development and the application that are restricting the rapid investment casting based on photocuring (SL).

Summary of the invention

The object of the invention designs a kind of rapid investment casting method based on photocuring (SL) exactly, simple to operate, group tree is firm, reduce costs, plant casting shell in roasting process is difficult for cracking.

A rapid investment casting method based on photocuring (SL), comprises following operating procedure main points:

1) the three-dimensional digital-to-analogue of mo(u)lded piece is obtained;

2) data processing:

Casting techniqueization is processed and ingate is arranged on colophony prototype; Again three-dimensional digital-to-analogue is taken out to shell and process the hollow structure forming with mesh-supported; Finally at colophony prototype, stamp to reserve on the hole of resin and the outer face at ingate and open hole;

3) photocuring (SL) colophony prototype and wax running gate system are made:

In 3D printing device, make photocuring (SL) colophony prototype, in order to replace moltening mold castings wax pattern; In wax running gate system, with the ingate junction of colophony prototype, groove is set;

4) on photocuring (SL) colophony prototype, steam vent is set: vertical bonding rod wax on the outer surface at colophony prototype;

5) organize compound wax tree: ingate is inserted in groove and is adhesively fixed; Again running gate system is connected on hanger;

6) be stained with slurry shell processed;

7) de-running channel wax:

The arenaceous shell of de-running channel wax front opening rod wax outer end after shell processed, with boiling hotization of the instrument rod wax of heating, and scalds the resin thin-walled formation steam vent of wearing with rod wax junction; Remove again running channel wax;

8) roasting deresination: adopt high temperature to enter stove, make colophony prototype conflagration;

9) smelting and pouring: block steam vent with fire clay before cast;

10) foundry goods post processing.

Advantage of the present invention is:

1) because wax running gate system can be used the existing general wax running channel of foundry, need not make specially, cost is low, cycle is short, only with complex parts, by wax pattern, adopting the 3D of photocuring (SL) mode that cost is higher to print resin casting makes, by wax running gate system and photocuring (SL) colophony prototype, form compound module again, greatly reduce cost and the production cycle of the rapid investment casting based on photocuring (SL);

2) rod wax is set on colophony prototype and forms steam vent, during roasting, the air of hollow resin prototype inside is identical with outside air, can not produce expansion, thus the cracking while reducing the deresination of casting Baking;

3) by the groove that connects ingate is set in wax running gate system, increase wax bond area and be connected rigidity, group tree being connected more firm, operating aspect; At ingate and running gate system junction, through hole is set, forms main steam vent after dewaxing, resin burning intake and exhaust while being conducive to roasting, increase combustion efficiency and reduce casting Shell cracking;

4) colophony prototype forms the hollow honeycomb of thin-walled, and during roasting, the support of honeycomb inside takes the lead in rupturing, and the outer wall of colophony prototype is lost to support, and colophony prototype type wall inwardly subsides when roasting, can not be split up casting shell; During roasting, module high temperature enters stove, can make colophony prototype moment conflagration, reduces the pressure-acting time to casting shell.

Accompanying drawing explanation

Fig. 1 is embodiment of the present invention process method flow chart;

Fig. 2 is embodiment of the present invention wax injection system structure schematic diagram;

Fig. 3 is photocuring (SL) the colophony prototype structural representation that embodiment of the present invention 3D prints;

Fig. 4 is the compound wax tree modular structure of embodiment of the present invention schematic diagram.

In figure: 1-colophony prototype; 2-ingate; 3-wax running gate system; 4-groove; 5-rod wax; 6-hanger

The specific embodiment

Below in conjunction with accompanying drawing, the invention will be further described.

Be illustrated in figure 1 embodiment of the present invention process method flow chart, and in conjunction with shown in Fig. 2, Fig. 3, Fig. 4, a kind of rapid investment casting method based on photocuring (SL), its main operational steps and main points are as follows:

1) the three-dimensional digital-to-analogue of mo(u)lded piece is obtained:

Different from conventional solvent casting mode, the wax pattern that rapid investment casting based on photocuring (SL) does not need to make mo(u)lded piece, also just do not need to make to press wax-pattern tool, only need the three-dimensional digital-to-analogue of mo(u)lded piece, the mode of printing by 3D is produced colophony prototype 1 and is replaced wax pattern.The three-dimensional digital-to-analogue of obtaining mo(u)lded piece can be by carrying out reverse measuring or by designer's Top-Down Design to existing part;

2) data processing:

Three-dimensional digital-to-analogue to mo(u)lded piece is carried out casting technique processing, as the curving of castings, increase allowance, the part that do not cast out is filled up etc., according to the metal species of required cast, determine the amount of contraction of molten metal, if the part material of required casting is stainless steel, three-dimensional digital-to-analogue structure needs whole amplification approximately 2%;

In the three-dimensional digital-to-analogue of mo(u)lded piece, add ingate; The size of ingate is greater than the ingate size of conventional model casting; While being convenient to roasting, air enters colophony prototype and makes sufficient combustion, and can discharge flue gas;

Three-dimensional digital-to-analogue is taken out to shell and process, be processed into the thin-wall construction of inner hollow, inner increasing supported the netted honeycomb of formation;

At colophony prototype 1, make the hole that reserves resin; After the position in hole is chosen in and facilitates 3D to print, the inner uncured resin of colophony prototype fully flows out, can be a plurality of holes, after 3D has printed, when post processing or when group sets, will block, and sealing, prevents from being stained with slurry in slurry shell process processed and enters colophony prototype 1 inside; The mode in shutoff resin hole has multiple, can use after smearing resin and solidify by UV-irradiation, also can by the sticking plaster dissolving, fill up with hot melt rubber stick, also can fill and lead up shutoff with wax;

Hole is opened in outer face at ingate 2, the sectional dimension of through hole is large as far as possible, but in order to guarantee the adhesive strength with wax running gate system 3, the sectional dimension of through hole be generally less than ingate 2 outer face area 1/3rd, if through hole is too large, be not easy bondingly with wax running gate system 3, bonding strong degree reduces; Ingate 2 is arranged on colophony prototype 1, is conducive to group tree; The effect that increases ingate 2 end-face holes is after de-running channel wax, during roasting casting shell, this hole can become effective air and the flue gas access way of resin burning, the flue gas producing after providing more oxygen and being conducive to burn to the burning of colophony prototype 1 is discharged casting shell, reduces colophony prototype 1 inner air and adds the possibility that flue gas pressures that thermal expansion and colophony prototype 1 burning produce causes casting Shell cracking; This through hole also can be used as a hole of flowing out resin, but the shutoff especially when group tree of this through hole, is directly inserted on the groove 4 of wax running gate system 3 and gets final product self-plugging;

To the data acquisition of finishing dealing with STL formatted output; Also can be other form that 3D printing device can read.

3) photocuring (SL) prototype and wax running gate system are made:

Photocuring (SL) prototype is made on technical grade 3D printing device, adopts photosensitive resin raw material, and precision can reach 0.1 millimeter or 0.1%, can meet casting requirement completely; The data importing 3D printing computer of having handled well, before making, need the STL data to importing carry out layering processing and add bottom support, 0.1 millimeter of lift height, layering is processed and is added bottom support and also can when aforementioned data is processed, complete; After completing, need to colophony prototype 1 clean, the post-processing operation such as polishing; As shown in Figure 3, embodiment mo(u)lded piece is to lead wheel-class parts to the colophony prototype 1 of producing, and ingate 2 is arranged on excircle, conveniently sands and is stained with slurry shell processed;

Simultaneously, wax running gate system 3 is prepared by foundry, as shown in Figure 2, in wax running gate system 3, with ingate 2 junctions of colophony prototype 1, groove 4 is set, the cross section of the cross-sectional sizes of groove 4 and ingate 2 is suitable, and ingate 2 positions and structure on the position of groove 4, structure and colophony prototype 1 match; With respect to conventional model casting, the size outline of the wax casting system 3 of the rapid investment casting based on photocuring (SL) is larger, enters required oxygen when the discharge of flue gas and colophony prototype 1 burn while being convenient to roasting; Casting system shared total share in model casting is larger, if the mode that also adopts 3D to print is made, will certainly increase cost of manufacture and strengthen fabrication cycle, wax is cheap and easy to get, adopt wax casting system 3 greatly to reduce production costs, and wax casting system 3 is in the standardization of model casting workshop, for different foundry goods, only need to select; Making groove 4 can make by hand with instruments such as wax spatulas, makes easily.

4) steam vent is set on photocuring (SL) colophony prototype:

Before group tree, as shown in Figure 4, bonding rod wax 5 on thick most of outer surface of the colophony prototype 1 of hollow, the diameter 5-8 millimeter of rod wax 5, length is greater than 20 millimeters, is vertically bonded on the surface of colophony prototype 1; Can be bonding with bonding wax, also can on colophony prototype 1, make a call to a hole that is slightly smaller than rod wax 5 diameters, rod wax 5 is inserted to location, substantially fixing, and then fixing with wax sealing; After shell processed, before de-running channel wax, with hacksaw, cut or grinding-wheel grinder is opened the arenaceous shell of rod wax 5 outer ends, with burning red iron wire boiling hotization rod wax 5, and the boiling hot type wall of wearing with the colophony prototype 1 of rod wax 5 junctions, form steam vent casting on shell; Before cast, need to block steam vent with fire clay, prevent that molten metal from leaking; The quantity of steam vent can arrange a plurality of according to part difference;

5) organize compound wax tree:

As shown in Figure 4, on the contact-making surface of the ingate 2 on photocuring (SL) colophony prototype 1 and the groove 4 of wax running gate system 3, smear the bonding wax dissolving, ingate 2 is inserted in grooves 4 firm fixing; In wax running gate system 3, have the embedded nut that connects hanger 6, there is screw thread the lower end of hanger 6, and the mode that can be threaded connection is connected to wax running gate system 3 on hanger 6; Because reliable like that not as between wax and wax of wax and resin bonding, after 3 groups of trees of colophony prototype 1 and wax running gate system, in being stained with slurry hanging sand process, be easy to come off, groove 4 is set in wax running gate system 3, is conducive to ingate 2 and is reliably connected with wax running gate system 3, increase the contact-making surface of bonding wax; Meanwhile, ingate 2 inserts posterior lobe in groove 4 has increased steadiness and rigidity; After group tree, can to module, clean with liquid detergent or other cleaning agents;

6) be stained with slurry shell processed:

Being stained with slurry shell processed identical with conventional model casting, can be that total silicon colloidal sol is cast shell, also can Ludox and the composite casting shell of waterglass, and can be also that silester is cast shell;

7) de-running channel wax:

Before de-running channel wax, first will scald and wear the rod wax 5 being bonded on colophony prototype 1, the steam vent of formation is removed running channel wax in autoclave dewaxing still or low temperature oven;

8) roasting deresination:

High temperature enters stove, guarantees to have in stove the oxygen of enough colophony prototype 1 burnings, and colophony prototype 1 is discharged outside casting shell after high-temperature gasification, casts investment shell intensity raising simultaneously and reaches cast requirement; Roasting adopts gas furnace, resistance furnace all can; The general about 550--750 ℃ of charging temperature; Sintering temperature 800--1100 ℃, is incubated approximately 2 hours;

9) smelting and pouring:

This operation and conventional model casting just as; Before cast, to block steam vent with fire clay, prevent that molten metal from leaking, with compressed air, blow away the residual ash content of casting shell inside, also can water or alcohol clean; Finally be heated to the preheat temperature cast of casting metal requirement;

10) foundry goods post processing:

By conventional postprocessing working procedures such as clear shell, cutting dead head, polishings, after check, obtain cast product.

Claims

1. the rapid investment casting method based on photocuring (SL), comprises following operating procedure main points:

1) the three-dimensional digital-to-analogue of mo(u)lded piece is obtained;

2) data processing:

Casting techniqueization is processed and ingate (2) is arranged on colophony prototype (1); Again three-dimensional digital-to-analogue is taken out to shell and process the hollow structure forming with mesh-supported; Finally at colophony prototype (1), stamp and reserve the hole of resin and open hole on the outer face of ingate (2);

3) photocuring (SL) colophony prototype (1) and wax running gate system (3) are made:

In 3D printing device, make photocuring (SL) colophony prototype (1), in order to replace moltening mold castings wax pattern; Ingate (2) junction upper in wax running gate system (3) and colophony prototype (1) arranges groove (4);

4) steam vent is set on photocuring (SL) colophony prototype (1): vertical bonding rod wax (5) on the outer surface of colophony prototype (1);

5) organize compound wax tree: ingate (2) is inserted in groove (4) and is adhesively fixed; Again running gate system (3) is connected on hanger (6);

6) be stained with slurry shell processed;

7) de-running channel wax:

The arenaceous shell of de-running channel wax front opening rod wax (5) outer end after shell processed, with boiling hotization of the instrument rod wax (5) of heating, and scalds the resin thin-walled formation steam vent of wearing with rod wax (5) junction; Remove again running channel wax;

8) roasting deresination:

9) smelting and pouring: block steam vent with fire clay before cast;

10) foundry goods post processing.