Background technology
Along with the continuous progress of internal-combustion engine technology, also improving constantly as the technical requirement of the product such as internal combustion engine frame, end cap of internal combustion engine core component, existing market product difficulty mainly concentrates on, and cavity shape complexity, oil pipe is more, dimensional accuracy is high.Oil pipe is as the key area of internal combustion engine mainframe, in order to ensure dimensional accuracy, and tubing bending degree, the founding method of the oil pipe particular importance that seems, the founding method of tradition core, specific as follows: the 1) location of oil pipe core: fuse is by core print location, location, bottom, this kind of localization method is relatively applicable to the fuse that short transverse is less, larger for short transverse, the oil pipe core that diameter is smaller, only depend on nowel location core print, the easy run-off the straight of fuse, causes oil pipe wall thickness and size generation deviation; 2) selection of oil pipe core core iron: fuse generally adopts screw-thread steel core iron, this kind of core iron intensity difference, easily bending, cause oil pipe core self to be easily out of shape, cause tubing bending distortion comparatively serious; 3) selection of oil pipe core sand kind: conventional cast is selected quartzy resin sand, and the casting flaws such as shrinkage porosite, scab easily occur oil pipe, is difficult to meet client's quality requirement; 4) oil pipe core bending prevention: to be mainly that ingate flings core relevant with temperature, buoyancy, molten iron flow velocity in the flexural deformation of oil pipe, traditional process program, only depend on the intensity of fuse itself to resist molten iron buoyancy, prevent fuse distortion, actual productions prove in a large number, and the distortion of oil pipe core is still very serious.
Also do not overcome so far the method for above-mentioned defect.
Summary of the invention
The object of the invention is to overcome the defect of prior art, a kind of technique uniqueness is provided, can improves casting quality, reduce the casting method of a kind of internal combustion engine core oil pipe of product percent defective.
The present invention realizes in the following way:
A kind of casting method of internal combustion engine core oil pipe, comprise moulding, coremaking, mould assembling and cast, it is characterized in that: in the time of coremaking, adopt oil pipe core location, be that oil pipe core is through all inner chamber cores, determine the position of oil pipe by both sides external mold core print location, selecting steel pipe is core iron, and the raw material of oil pipe core is chromite sand; When mould assembling, oil pipe core flexural deformation prevention termination increases evaporative pattern shrinkage joint, and blowing compressed air is forced cooling, and oil pipe position in the time of mould assembling, increases special Leakproof chaplet;
Described core iron steel tube surface intersection is provided with the logical eye of ф 5mm, and steel pipe carries out abundant ball blast before use simultaneously;
Described termination increases evaporative pattern shrinkage joint, forms oil pipe core expansion track;
Described ingate is away from oil pipe core;
Described blowing compressed air forces to be cooled to 4 points of steel pipes of oil pipe core inlet end employing wall thickness 3mm, as inlet channel, at the trapped line pressure valve of air inlet pipe and airduct junction installation internal diameter ф 6mm, control the pressure of cooling-air, after good under oil pipe core, the passage leaving in advance from sandbox outside, air inlet pipe is inserted in the core iron at oil pipe core center, and determine according to actual conditions the degree of depth that blast pipe inserts, air inlet pipe and oil pipe core steel pipe core iron junction are used adhesive tape to seal, then back-up sand shutoff, under mould assembling after complete fuse, in core steel pipe core iron, be blown into cooling-air, force cooling, in the time of cast, in the time that arriving core height, metal bath surface starts ventilation, this part liquidus temperature is 1166 DEG C, need 28 minutes from being poured into liquidus temperature, gassing time is defined as to 60 minutes.
The present invention has following effect:
1) method uniqueness, the scab that effectively solves oil pipe and shrinkage porosite problem: the tubing diameter of current most IC engine airframes is not at Φ 70-120mm etc., because oil pipe cylinder core is longer, therefore core iron will have enough intensity, otherwise under Gravitative Loads, core iron flexural deformation, causes core to be out of shape and cracks.Simultaneously for preventing that molten iron temperature is too high due to oil pipe around, cause the flexural deformation of oil pipe core, layer of sand sintering, want the thickness of reasonable design oil pipe core layer of sand, make oil pipe environment temperature be delivered to rapidly center core iron by layer of sand, reject heat to and in atmosphere, carry out control oil pipe molten iron temperature around by core iron.By testing and proving, the application selects steel pipe as core iron.Steel tube surface intersection is bored the logical eye of ф 5mm, and guarantee oil pipe core is given vent to anger, and steel pipe must carry out abundant ball blast before use simultaneously, and object is increase steel tube surface roughness, can be with sand; For pre-preventing oil pipe scab and shrinkage porosite problem, when production, all oil pipe cores all adopt chromite sand to produce, and effectively solve scab and the shrinkage porosite problem of oil pipe.
2) can fully solve the fixation problem of oil pipe, make tubing size more accurate: the horizontal oil pipe core of internal combustion engine exists following characteristics: fuse is circular between Φ 70-120mm of diameter mostly or is similar to the straight cavity of circular length, the about 500-5000mm of length is not etc., pass all inner chamber cores from frame one side to an other side, it is an independently cavity, in order to ensure dimensional accuracy, oil pipe core can not only depend on the core print face location through inner chamber core, must be through all inner chamber cores, determine the position of oil pipe by both sides external mold core print location, oil pipe core flexural deformation prevention: first termination increases evaporative pattern shrinkage joint: temperature: enter after casting mold at molten iron, between molten iron and oil pipe core, there is heat exchange.Be the transfer of heat of molten iron within the scope of oil pipe core to oil pipe core, in whole heat exchanging process, oil pipe core is subject to the impact of molten iron self heat and crystallization process release heat around.Until molten iron temperature and oil pipe core temperature reach balance within the scope of oil pipe core.In heat exchanging process, oil pipe core expands because the rising of temperature produces, if core two ends are all fixed on two end supports seat, originally straight oil pipe can flexural deformation.According to knowhow in early stage, oil pipe core two ends are all designed to free-extension end.Gap must be left in two ends, and expansion joint is set.Make its energy free-extension in the time of expanded by heating.In technique, adopt evaporative pattern to form expansion joint.Oil pipe core swell increment can be calculated by following formula:
L=L0(1+αt)
L---length after core expanded by heating;
L0---core length;
α---the coefficient of expansion;
T---core is molten iron temperature around;
Buoyancy: the buoyancy that oil pipe is subject to is relevant with the density of the density of molten iron, core and the lifting surface area of molten iron.Be subject to iron buoyancy of water by calculating oil pipe core very little, negligible.Molten iron flow velocity, ingate flings core: for preventing that molten iron from flinging core and making the rising of oil pipe core temperature and oil pipe core be subject to buoyancy increase, offering of ingate should be away from oil pipe core; Blowing compressed air is forced cooling: oil pipe core inlet end adopts 4 points of steel pipes of wall thickness 3mm, as inlet channel.At the trapped line pressure valve of air inlet pipe and airduct junction installation internal diameter ф 6mm, control the pressure of cooling-air.After good under oil pipe core, the passage leaving in advance from sandbox outside, inserts air inlet pipe in the core iron at oil pipe core center, and determines according to actual conditions the degree of depth that blast pipe inserts.Air inlet pipe and oil pipe core steel pipe core iron junction are used adhesive tape to seal, then back-up sand shutoff.Under mould assembling, after complete fuse, in core steel pipe core iron, be blown into cooling-air, force coolingly, but need to control the pressure of cooling-air, otherwise because cooling-air pressure is excessive, occur tiny crackle on core surface.Therefore in the time of cast, in the time that arriving core height, metal bath surface starts ventilation comparatively reasonable.Pass through formula: t >=KM, K---coefficient, large part 2.0 ~ 2.5; M---oil pipe modulus, calculates minute wherein K=2.2 of t >=8.9, M=2.01; This part liquidus temperature is 1166 DEG C, is reduced to liquidus temperature needs 28 minutes from being poured into, and gassing time is defined as to 60 minutes.
3) can fully solve the problem of giving vent to anger of oil pipe core, prevent that oil pipe from occurring bending, the defects such as fire of choking: increase Leakproof chaplet: for after further solving oil pipe core and being heated, cause tubing bending, oil pipe position in the time of mould assembling, increase special Leakproof chaplet, the structure of Leakproof chaplet as shown in Figure 4, in order to ensure that hydraulic pressure does not leak and stud not exclusively melts, play the effect of supporting fuse and the temperature distortion in casting process of opposing fuse, spend according to liquidus temperature 1168, simulate the diameter of determining Leakproof chaplet by MAGMA, ensure in the time of liquidus temperature, stud cylinder is not completely melted, anti-to determine
4) due to the minimizing of core quantity, reduce operator's labour intensity, improve production efficiency.
Detailed description of the invention
A kind of casting method of internal combustion engine core oil pipe, comprise moulding, coremaking, mould assembling and cast, it is characterized in that: in the time of coremaking, adopt oil pipe core positioning instant oil pipe core through all inner chamber cores, determine the position of oil pipe by both sides external mold core print location, selecting steel pipe is core iron, and the raw material of oil pipe core is chromite sand; When mould assembling, oil pipe core flexural deformation prevention termination increases evaporative pattern shrinkage joint, and blowing compressed air is forced cooling, and oil pipe position in the time of mould assembling, increases special Leakproof chaplet.
Described core iron steel tube surface intersection is provided with the logical eye of ф 5mm, and steel pipe carries out abundant ball blast before use simultaneously.
Described ingate is away from oil pipe core.
Described blowing compressed air forces to be cooled to 4 points of steel pipes of oil pipe core inlet end employing wall thickness 3mm, as inlet channel, at the trapped line pressure valve of air inlet pipe and airduct junction installation internal diameter ф 6mm, control the pressure of cooling-air, after good under oil pipe core, the passage leaving in advance from sandbox outside, air inlet pipe is inserted in the core iron at oil pipe core center, and determine according to actual conditions the degree of depth that blast pipe inserts, air inlet pipe and oil pipe core steel pipe core iron junction are used adhesive tape to seal, then back-up sand shutoff, under mould assembling after complete fuse, in core steel pipe core iron, be blown into cooling-air, force cooling, in the time of cast, in the time that arriving core height, metal bath surface starts ventilation, this part liquidus temperature is 1166 DEG C, be reduced to liquidus temperature needs 28 minutes from being poured into, gassing time is defined as to 60 minutes.
In figure, 1 is crust location core print; 2 is oil pipe core; 3 is core broad in the middle, and 4 is core iron; 5 is the logical eye of ф 5mm, and 7 is evaporative pattern shrinkage joint; 6 is dual-side core; 8 is air intake duct; In figure, 9 is air escape pipe.