CN104148585A - Casting method for nodular cast iron crankshaft used for internal combustion locomotive - Google Patents

Abstract

The invention relates to the technical field of a mechanical transmission system of an internal combustion engine, in particular to a casting method for a nodular cast iron crankshaft used for an internal combustion locomotive. The casing method includes the following steps: dividing a metal mold into blocks (sections), preserving a 4 mm contracting clearance between the blocks (sections) and producing Portland cement fluid sand by mixing. Strength of the sand is controlled between 1.5 MPa and 3.0 MPa, and the thickness of a sand-covering layer ranges from 15mm to 18mm. The Portland cement fluid sand fills the metal mold according to sand demanding volume of parts of a mold cavity, and a die sample is quickly pressed into the metal mold under the guidance ofa locating pin. Stripping time is approximately between 20 to 60 minutes. After stripping and patching, a plastic film is used to cover the sub-mold surface of a cast mould to protect the sand covering layer for more than 8 hours. The casting method for the nodular cast iron crankshaft used for the internal combustion locomotive improves rigidity of the cast mould, reduces sand inclusion defect rate of crankshaft cast parts, improves the solidification and cooling environment of the crankshaft cast parts, accelerates solidification and cooling of the cast parts, and reduces defects like dispersed shrinkage and black spots and so on, thereby producing cast mould with compact structure.

Description

The casting method of ductile iron crankshaft for diesel locomotive

Technical field

The present invention relates to combustion engine mechanical transmission system technical field, the casting method of ductile iron crankshaft for especially a kind of diesel locomotive.

Background technology

Ductile iron crankshaft overall size 4500mm × 440mm × 401mm for diesel locomotive, trunnion diameter phi 255mm, connecting rod neck diameter phi 219mm, heavily approximately 2 tons, because size is larger, complex structure, cannot adopt shell mould method to produce, therefore adopt sand mould casting method to produce, the method needs a large amount of chills, organization of production difficulty, and mold stiffness is lower, easily produce burning into sand, organize the defects such as not fine and close, percent defective is up to more than 50%.

Summary of the invention

In order to overcome the deficiency of existing technology, the invention provides the casting method of a kind of diesel locomotive ductile iron crankshaft.

The technical solution adopted for the present invention to solve the technical problems is: the casting method of ductile iron crankshaft for a kind of diesel locomotive, and its detailed process is as follows:

(1), when Fixture Design, metal mold should first piecemeal (or section), and between piece (or section) and piece (or section), reserves the constringency cleft of 4mm;

(2), the qualified portland cement fluid(ized)sand of mixed system, sand bond should be controlled at 1.5MPa～3.0MPa;

(3), covering sand layer thickness is 15mm～18mm; According to the mold thickness at the each position of die cavity, qualified portland cement fluid(ized)sand is inserted in metal mold, then, with alignment pin guiding, rapidly apperance is pressed in metal mold;

(4), stripping time, general about 20-60min;

(5), rise after die repair type, cover on casting mold die joint with plastic sheeting, layer of sand is covered in maintenance, curing time is no less than 8h.

The invention has the beneficial effects as follows,

(1) improve mold stiffness, lowered automatic modeling crankshaft casting burning into sand defect incidence;

(2) improve automatic modeling crankshaft casting and solidified cooler environment, accelerated the solidification cooling of foundry goods, shortened the eutectic transformation time, reduced the defect such as shrinkage porosite, blackspot, obtained the foundry goods of dense structure;

(3) adopt the method to produce diesel locomotive ductile iron crankshaft, yield rate reaches more than 95%, and has reference function for exploitation and the production of product of the same type.

Brief description of the drawings

Below in conjunction with drawings and Examples, the present invention is further described.

Fig. 1 is structural representation of the present invention.

In figure 1, foundry goods, 2, metal mold, 3, core, 4, cover layer of sand, 5, mo(u)ld top half, 6, mo(u)ld bottom half.

Detailed description of the invention

A casting method for ductile iron crankshaft for diesel locomotive, its detailed process is as follows:

(1), when Fixture Design, metal mold 2 should first piecemeal (or section), and between piece (or section) and piece (or section), reserves the constringency cleft of 4mm; While preventing from pouring into a mould, be out of shape when metal mold expanded by heating.

(2), the qualified portland cement fluid(ized)sand of mixed system, sand bond should be controlled at 1.5MPa～3.0MPa; Sand intensity is too low, easily causes foundry goods burning into sand, oozes the defects such as iron.Sand bond is too high, and foundry goods is in the time of solidification shrinkage, and the machinery obstruction that is subject to casting mold and core is larger, and the possibility that makes foundry goods produce hot tearing increases.

(3), that cement fluid(ized)sand covers sand layer thickness control is excessive,, by weakening the effect of metal mold, can not give full play to the advantage that its heat storage capacity is large, rigidity is high.Cover sand layer thickness control too small, moulding difficulty, foundry goods is difficult to successfully in type, take out while unpacking, even causes crankshaft breakdown.Suitable layer of sand 4 thickness that cover are 15mm～18mm.According to the mold thickness at the each position of die cavity, qualified portland cement fluid(ized)sand is inserted in metal mold, then, with alignment pin guiding, rapidly apperance is pressed in metal mold.

(4), because the setting rate of alumina cement fluid(ized)sand changes with the variation of temperature and humidity, therefore, be difficult to do unified regulation stripping time, general about 20-60min.

(5), rise after die repair type, cover on casting mold die joint with plastic sheeting, layer of sand is covered in maintenance, curing time must not be less than 8h.

The present invention has improved mold stiffness, has lowered automatic modeling crankshaft casting burning into sand defect incidence; Improve automatic modeling crankshaft casting and solidified cooler environment, accelerated the solidification cooling of foundry goods, shortened the eutectic transformation time, reduced the defect such as shrinkage porosite, blackspot, obtained the foundry goods of dense structure.Adopt the method to produce diesel locomotive ductile iron crankshaft, yield rate reaches more than 95%, and has reference function for exploitation and the production of product of the same type.

Claims (1)

1. a casting method for ductile iron crankshaft for diesel locomotive, is characterized in that, its detailed process is as follows:

(1), when Fixture Design, metal mold should first piecemeal (or section), and between piece (or section) and piece (or section), reserves the constringency cleft of 4mm;

(2), the qualified portland cement fluid(ized)sand of mixed system, sand bond should be controlled at 1.5MPa～3.0MPa;

(3), covering sand layer thickness is 15mm～18mm; According to the mold thickness at the each position of die cavity, qualified portland cement fluid(ized)sand is inserted in metal mold, then, with alignment pin guiding, rapidly apperance is pressed in metal mold;

(4), stripping time, general about 20-60min;

(5), rise after die repair type, cover on casting mold die joint with plastic sheeting, layer of sand is covered in maintenance, curing time is no less than 8h.