CN101987349A - Casting technology of stainless steel hydroelectric runner lower ring - Google Patents

Abstract

The invention relates to a casting technology of a stainless steel hydroelectric runner lower ring, comprising the following steps: tooling preparation, molten steel pouring, opening for unpacking and heat treatment. The casting technology is characterized in that a casting section is designed according to the size of workpieces by taking progressive solidification as a rule, and a pouring model is built; a bottom pouring mode is adopted for pouring at the pouring temperature of 1550-1590 DEG C and at the pouring speed of 6-30 mm/s; the process of pouring is finished for once, and then heat preservation covering agent is added; the principle for determining the casting section is as follows: the thickness of the casting section is increased by less than 25-30 mm with raising of each meter. The heat preservation covering agent is perlite slag-accretion heat preservation covering agent. The process of heat treatment is characterized by comprising of once normalization and twice tempering treatments. The casting technology of the invention has the beneficial effect that the technology effectively solves the problems of deformation, crackles, cold shut, double skins, micro shrinkage and the like in the existing casting production process.

Description

Stainless steel water power runner is the casting technique of ring down

Technical field

The present invention relates to the casting technique field, relate in particular to the casting technique of ring under a kind of stainless steel water power runner.

Background technology

At present the stainless steel rotary wheel of hydroelectricity generator group down the casting technique of ring be that the cast compensation rate that the method that adopts rising head to mend lining under rising head increases foundry goods makes it consecutive solidification, rising head is mended lining and will is with surplus temperature to carry out the tempering second time then with method (about 200 ℃) excision continuously after for the first time positive tempering of carbon arc air gouging before the foundry goods machine adds.Because workpiece body is a circular arc camber, mend bad easily the causing lacking of workpiece body misrun or benefit lining amount excision of lining excision amount control, make troubles for the processing of postorder, especially temperature control is bad in the process of excision, it thermal man does not increase, it is cold again because cooling is too fast, can not the regulation temperature range in disposable continuous excision, general as can not once resecting, requirement must reheat or advance could cut after kiln is handled once more, and carbon arc air gouging can defectives such as micro-crack occur at the cutting position to the foundry goods body, mending lining other positions of position and workpiece compares thick a lot, the long-time overheated defective such as microcosmic shrinkage porosite that also easily produces in this position has certain pollution to environment in the carbon arc air gouging process in addition, and operator itself is also had certain injury.

Summary of the invention

The casting technique that the purpose of this invention is to provide under a kind of stainless steel water power runner ring, this technology have been cancelled rising head and have been mended lining, solved in foundry production, exist problems such as distortion, crackle, cold shut pipe, microcosmic shrinkage porosite are arranged.

For achieving the above object, the present invention is achieved through the following technical solutions:

Stainless steel water power runner is the casting technique of ring down, comprise that frock preparation, pouring molten steel, cooling are unpacked, heat treatment, it is characterized in that, according to workpiece size is that principle is designed the foundry goods cross section and set up the cast model with the consecutive solidification, pours into a mould in the mode of rising pouring, and pouring temperature is controlled at 1550 ℃-1590 ℃, poring rate 6-30mm/s, once watering expires, and adds thermal-insulating covering agent, and definite principle in foundry goods cross section is: the thickness increase in one meter foundry goods cross section of every rising is no less than 25-30mm.

Described thermal-insulating covering agent is the perlite polyslag heat-insulating covering agent.

Described heat treatment process is: after through a normalizing, drawing process the gross imperfection of cast(ing) surface is handled, advanced the kiln double tempering after the processing again;

The process of normalizing for the first time: the programming rate with≤20 ℃/h heats foundry goods, be heated to 690 ± 20 ℃ from room temperature, insulation is 2-4 hour under this temperature, and then foundry goods is heated with the programming rate of≤30 ℃/h, be heated to 1000-1060 ℃, insulation is 10-14 hour under this temperature, and room temperature is reduced in the air cooling then;

Drawing process for the first time: the programming rate with≤40 ℃/h heats foundry goods, is heated to 600-660 ℃ from room temperature, and insulation is 12-16 hour under this temperature, and room temperature is reduced in the air cooling then;

Drawing process for the second time: the programming rate with≤40 ℃/h heats foundry goods, is heated to 600-640 ℃ from room temperature, and insulation is 14-16 hour under this temperature, and room temperature is reduced in the air cooling then.

Compared with prior art, the invention has the beneficial effects as follows:

1) cancel rising head and mended lining, reduced cutting output, defectives such as the injury micro-crack that when having eliminated carbon arc air gouging the foundry goods body has been caused, and solve problems such as the distortion that in casting process, exists, microcosmic shrinkage porosite;

2) relative wall thickness of workpiece had also reduced than originally, poring rate has increased for same workpiece, the casting defects such as cold shut pipe that produce slowly because of poring rate have been reduced, wall thickness heat treated temperature retention time also shortened accordingly, reduce the production cycle of workpiece, can carry out conventional mechanical processing after the heat treatment.

Description of drawings

Fig. 1 is the foundry goods outline drawing that the band rising head is mended lining;

Fig. 2 is the foundry goods schematic cross-section that the band rising head is mended lining;

Fig. 3 is a schematic cross-section of the present invention;

Fig. 4 is a cross section profile dosage schematic diagram of the present invention.

The specific embodiment

Below in conjunction with accompanying drawing the specific embodiment of the present invention is described further:

Stainless steel water power runner is the casting technique of ring down, comprises that frock preparation, pouring molten steel, cooling are unpacked, heat treatment, and this method is on the basis of existing technology rising head to be mended the lining cancellation, looks for solidification gradient by the processing capacity of foundry goods, makes it consecutive solidification.Its process is: by being that principle is designed the foundry goods cross section and set up the cast model with the consecutive solidification according to workpiece size, and above-mentioned model is tested and analyzing by China casting CAE casting simulation software systems.This technology is poured into a mould in the mode of rising pouring, pouring temperature is controlled at 1550 ℃-1590 ℃, poring rate 6-30mm/s, once water full, the stream of demanding perfection, steadily, cast fast, add the perlite polyslag heat-insulating covering agent, definite principle in foundry goods cross section is: the thickness increase in one meter foundry goods cross section of every rising is no less than 25-30mm.

Heat treatment process is: after through a normalizing, drawing process the gross imperfection of cast(ing) surface is handled, advanced kiln after the processing again and carry out double tempering;

The process of normalizing for the first time: the programming rate with 20 ℃/h heats foundry goods, is heated to 690 ℃ from room temperature, and insulation is 4 hours under this temperature, and then foundry goods is heated with the programming rate of 30 ℃/h, be heated to 1060 ℃, insulation is 10 hours under this temperature, and room temperature is reduced in the air cooling then;

Drawing process for the first time: the programming rate with 40 ℃/h heats foundry goods, is heated to 660 ℃ from room temperature, and insulation is 16 hours under this temperature, and room temperature is reduced in the air cooling then;

Drawing process for the second time: the programming rate with 40 ℃/h heats foundry goods, is heated to 640 ℃ from room temperature, and insulation is 16 hours under this temperature, and room temperature is reduced in the air cooling then.

This technology can be selected the form of many rising heads or the form of an annular rising head as required.

See Fig. 1, Fig. 2, Fig. 3, the optimization of this technology is on the basis of original technology rising head to be mended the lining cancellation, is that principle determines that castings sectional makes it from the foundry goods bottom gradually to the top consecutive solidification with the consecutive solidification.

See Fig. 4, after molten steel is filled with mold cavity, along with temperature descends gradually, the part that foundry goods is thin is solidified earlier, therefore this stainless steel water power runner solidifies earlier ring foundry goods bottom down, in order to guarantee foundry goods consecutive solidification from bottom to top, the molten steel horizontal plane upwards moves L, the one-sided recruitment a of casting thickness B is no less than 12.5～15mm/ rice, and the measuring vertical of B is considered the planform characteristics and the castability requirement of foundry goods in the profile bus among the embodiment, a takes 25mm/ rice, the artificial feeding gradient that forms consecutive solidification makes the foundry goods dense internal organization, can reach foundry goods UT-2 level flaw detection requirement.

After for the first time positive tempering, can handle the gross imperfection of cast(ing) surface, advance the kiln double tempering then, reduced heat treated number of times, shortened the production cycle, reduced production cost, reduced environmental pollution, mended lining, reduced to mend lining and give problems such as micro-crack that foundry goods brought, cold shut, pipe, microcosmic shrinkage porosite because of rising head is set because cancelled rising head in when cutting.The problem on deformation of workpiece has also obtained corresponding improvement.Fig. 3 section ratio Fig. 2 compares according to the consecutive solidification principle in the cross section and has done correction, but in fact total molten steel amount consumption is far below prior art.

Claims (3)

1. stainless steel water power runner descends the casting technique of ring, comprise that frock preparation, pouring molten steel, cooling are unpacked, heat treatment, it is characterized in that, according to workpiece size is that principle is designed the foundry goods cross section and set up the cast model with the consecutive solidification, pours into a mould in the mode of rising pouring, and pouring temperature is controlled at 1550 ℃-1590 ℃, poring rate 6-30mm/s, once watering expires, and adds thermal-insulating covering agent, and definite principle in foundry goods cross section is: the thickness increase in one meter foundry goods cross section of every rising is no less than 25-30mm.

2. stainless steel water power runner according to claim 1 is the casting technique of ring down, it is characterized in that described thermal-insulating covering agent is the perlite polyslag heat-insulating covering agent.

3. stainless steel water power runner according to claim 1 is the casting technique of ring down, it is characterized in that described heat treatment process is: after through a normalizing, drawing process the gross imperfection of cast(ing) surface is handled, advanced the kiln double tempering after the processing again;

The process of normalizing for the first time: the programming rate with≤20 ℃/h heats foundry goods, be heated to 690 ± 20 ℃ from room temperature, insulation is 2-4 hour under this temperature, and then foundry goods is heated with the programming rate of≤30 ℃/h, be heated to 1000-1060 ℃, insulation is 10-14 hour under this temperature, and room temperature is reduced in the air cooling then;

Drawing process for the first time: the programming rate with≤40 ℃/h heats foundry goods, is heated to 600-660 ℃ from room temperature, and insulation is 12-16 hour under this temperature, and room temperature is reduced in the air cooling then;

Drawing process for the second time: the programming rate with≤40 ℃/h heats foundry goods, is heated to 600-640 ℃ from room temperature, and insulation is 14-16 hour under this temperature, and room temperature is reduced in the air cooling then.

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