CN101927499B

CN101927499B - Method for making robot base casting

Info

Publication number: CN101927499B
Application number: CN2009100536658A
Authority: CN
Inventors: 徐清; 蔡中强; 李安全; 毕永成; 张宗来
Original assignee: HUAXIN ALLOY CO Ltd SHANGHAI
Current assignee: HUAXIN ALLOY CO Ltd SHANGHAI
Priority date: 2009-06-23
Filing date: 2009-06-23
Publication date: 2012-08-01
Anticipated expiration: 2029-06-23
Also published as: CN101927499A

Abstract

The invention relates to a method for making a robot base casting, which comprises the following processes: sand-milling, molding, making a core, assembling the core, setting the core, closing a mold, smelting furnace charge, discharging, globurizing, inoculating, pouring, cooling, opening a box, cleaning the casting and testing the product quality. In the steps of core making, core assembling and core setting, three sand cores are connected and fixed in series, and integrally suspended into the mold cavity after the assembling outside the mold. The furnace charge smelting step comprises the steps of furnace charge proportioning and smelting in a medium-frequency induction furnace; and the furnace charge comprises the following components in percentage by mass: 35-45% of pig iron, 35-45% of returning iron and 10-30% of scrap steel. The discharging, globurizing and inoculating process comprises globurization and one-step inoculation of silicon and barium. The tensile strength of the robot base casting is greater than or equal to 500 MPa, the yield strength is greater than or equal to 320 MPa, the percentage of elongation is greater than or equal to 7%, and the hardness is 170-230 HBS. The globurizing rate of the metallurgical structure of the casting is greater than or equal to 80%, the size of graphite is Grade 4-6, the content of pearlite is 40-60%, and the casting does not contain carbides.

Description

The casting method of robot base foundry goods

Technical field

The present invention relates to casting field, particularly a kind of casting method of robot base foundry goods.

Background technology

The robot product extensively applies to modern manufacturing industry, and wherein, 20136 humanoid robot bases are maximum foundry goods of production difficulty in the series matching spare.The material trademark of cast product is QT500-7, and the mechanical performance of products index is: tensile strength >=500MPa, and yield strength >=320MPa, percentage elongation >=7%, it is 170～230HBS that casting hardness requires; The metallographic structure of product requires: nodularization rate >=80%, and 4～6 grades of graphite sizes, pearlite 40～60%, foundry goods do not allow carbide and exist, and the dimension precision requirement of cast product is than higher.Therefore how to satisfy above-mentioned specification requirement, become the key of foundry robot's base cast product.

Summary of the invention

The robot base product of producing the purpose of this invention is to provide a kind of casting method of robot base foundry goods, so that can satisfy above-mentioned specification requirement.

For achieving the above object, the technical scheme that the present invention adopts is:

The casting method of robot base foundry goods, its step comprise mix sand, moulding, coremaking, core assembly, down core, mould assembly, furnace charge melting, the spheroidization and inoculation that taps a blast furnace handle, cast, cooling, unpacking, casting cleaning and product quality inspection; Wherein, in described coremaking, core assembly and the following core step, ready made 3 cores big core of casting technique formation with many core assemblies; Described furnace charge melting step comprises, the composition quality percentage of furnace charge: the pig iron 35%～45%, foundry return 35～45%, steel scrap 10%～30%; Melting adopts medium-frequency induction furnace to carry out the melting of iron liquid, and smelting temperature is 1480～1560 ℃; The described spheroidization and inoculation treatment process of coming out of the stove comprises spheroidising and two steps of inoculated of silicon barium; In the described cast operation, pouring temperature is controlled at 1380～1450 ℃.

In the coremaking operation of the present invention; An external chill is placed in the position that thick large part is put open riser on corresponding foundry goods top in the loam core, chill shape and core cavity match; Its effect is a cooling velocity of quickening riser pad bottom foundry goods part, prevents that this thick large part from producing shrinkage defect.

Cast product shape more complicated of the present invention, the main part of foundry goods are vertically assembled by 3 cores and are formed, because casting dimension accuracy requires how to guarantee that than higher 3 relative positions between the core are key problem in technology.Because between die cavity and the core and all have the gap between core and the core, when 3 cores were lowered to die cavity respectively in order, can add up in these gaps, can cause accumulated error, causes the dimensional accuracy of cast product not reach specification requirement.

The way that the present invention solves is to be improved to a big core to 3 cores; Promptly 3 cores big core of casting technique formation with core assembly; When outside die cavity, carrying out core assembly, the inner relative position of fuse is just controlled easily, thereby has guaranteed the dimensional accuracy of cast product.

The present invention places floamed ceramics filtrating piece at mo(u)ld bottom half (corresponding sprue position) before mould assembly, its effect is: (1) is fallen the contaminant filter in the iron liquid when iron liquid casting, in order to avoid impurity gets into die cavity and produces dreg defect; (2) slow down the flowing velocity of iron liquid, avoid iron liquid impulsive force excessive and cause sand washing casting flaw.

Furnace charge melting step of the present invention comprises configuration furnace charge and two parts of smelting iron liquid.Furnace charge configuration quality percentage is: the pig iron 35～45%, foundry return 35～45%, steel scrap 10～30%; Melting adopts medium-frequency induction furnace to carry out the melting of iron liquid, and smelting temperature is 1480～1560 ℃.

The described spheroidization and inoculation treatment process of tapping a blast furnace comprises tap a blast furnace spheroidising and two steps of inoculated of silicon barium.The nodulizer total amount that wherein said spheroidising step adds is 1.0～2.4% of the melting amount of tapping a blast furnace, and the chemical composition mass percent of nodulizer is: Mg 5.0～7.0%, RE 1.0～3.0%, Si 38～48%, Ca 1.0～3.0% and Fe surplus.

The granularity of said nodulizer is 4～25mm.

The addition of the silicon titanate innoculant that inoculated of described silicon barium is used is 0.50～1.2% of the melting amount of tapping a blast furnace, and the chemical composition mass percent of silicon titanate innoculant is: Si 60～70%, Ca0.8～2.2%, Al 1.0～2.0%, Ba 1.5～6.0% and Fe surplus.

The granularity of described silicon titanate innoculant is 5～25mm.

In the described cast operation, after process nodularization of iron liquid and the inoculated, the pouring temperature that guarantee iron liquid is at 1380～1450 ℃.

The chemical composition mass percent of cast product is: C 3.4～3.7%, Si 2.4～2.8%, Mn 0.30～0.60%, P≤0.07%, S≤0.03%, RE 0.01～0.04%, Mg 0.03～0.06%, surplus Fe and inevitable impurity.

The invention has the beneficial effects as follows:

After adopting casting method of the present invention, the tensile strength >=500MPa of the robot base cast product of producing, surrender is slight >=320MPa, percentage elongation >=7%, cast product hardness reaches 170～230HBS; In the metallographic structure of product, nodularization rate >=80%, 4～6 grades of graphite sizes, ball light body 40～60%, cast product does not have carbide.The dimensional accuracy of cast product meets specification requirement.

Description of drawings

Fig. 1 is the sketch map of one embodiment of the invention casting mold.

Fig. 2 is the vertical view of Fig. 1.

The specific embodiment

Embodiment 1

Referring to Fig. 1, Fig. 2, be example with the casting method of 20136 humanoid robot base foundry goods, comprise the steps:

(1) mulling moulding, coremaking

The robot base foundry goods carries out moulding and makes 3 cores after adopting automatic pug mixer to mix the system furan resin self curing sand.When making 3 cores, in each core, bury plug in advance, so that be fixed up 1,2,3 combinations of 3 cores at last.Pre-buried external chill on 1# core 1 in addition; Molding after moulding and the coremaking, repair type, coat and carry out skin drying.

(2) core assembly, following core and mould assembly

Be fixed up 3

cores

1,2,3 through pre-buried plug series combination; Form a big core, and measure the relative dimensions of big core with clamp, the qualified back of the size of big core integral body hangs in the die cavity of lower mold 200; Hang at last and cover casting mold 100, with waiting for pouring behind the tight case of bolt.

(3) furnace charge melting

Dispose furnace charge earlier, the composition mass percent of furnace charge is: the pig iron 40%, foundry return 40%, steel scrap 20%; Drop into medium-frequency induction furnace to the furnace charge that configures then and carry out the melting of iron liquid; Smelting temperature is 1540 ℃, leaves standstill insulation 5～10 minutes, lets impurity in the iron liquid is fully floating to come up; With gather take off after the slag agent is assembled come out of the stove outside, do not allow these impurity bands in the iron liquid of handling.

(4) spheroidization and inoculation that taps a blast furnace is handled

Comprise tap a blast furnace spheroidising and two steps of silicon barium inoculated, wherein spheroidising is adopted and is poured the method spheriodization process thereof, and the nodulizer granularity is 4～25mm; The nodulizer addition is 1.60%, and iron liquid tapping temperature is 1520 ℃, and for the first time the amount of tapping a blast furnace is 2/3 of the total amount of tapping a blast furnace; The reagentia time of nodulizer and iron liquid is 60～90 seconds; Scratch clean the scum silica frost on the iron liquid level after the question response effect finishes, add 0.60% silicon titanate innoculant and also stir, add remaining 1/3 iron liquid after again; Scratch clean the scum silica frost on iron liquid surface once more, on the iron liquid level, add thermal-insulating covering agent at last and go to pour into a mould.The chemical composition mass percent of the nodulizer that wherein adds is: Mg 6.05%, RE 2.10%, Si 43%, Ca 2.10% and Fe surplus.

The chemical composition mass percent of silicon titanate innoculant is: Si 64%, Ca 1.65%, Al 1.40%, Ba 4.15% and Fe surplus.The final chemical composition mass percent of cast product is: C 3.55%, Si 2.65%, Mn 0.40%, P 0.04%, S 0.025%, RE 0.02%, Mg 0.05% and Fe surplus.

(5) cast

The pouring temperature of iron liquid is 1395 ℃.Iron liquid pours into behind the cup footpath sprue 4 to the filter chamber 5; Iron liquid filters through floamed ceramics filtrating piece 51 in this chamber, removes the impurity in the de-iron liquid, and then iron liquid gets into first cross gate 6 and second cross gate 7 simultaneously; In this two cross gate; Impurity in the iron liquid is blocked again, and back iron liquid gets into second sprue 8 and the 3rd sprue 9 simultaneously again, and last iron liquid gets into the whole casting process of die cavity 12 completion from corresponding first ingate 10 and second ingate 11.In the casting process, it should be noted that the iron liquid level of iron liquid casting in open riser 13 should stop cast when reaching 1/3 height at once, pour into remaining 2/3 iron liquid from open riser 13 again,, improve the feeding capacity of rising head to improve the temperature of iron liquid in the rising head.

6) cooling is unpacked

7) casting cleaning

8) quality inspection

The product of disqualified upon inspection is eliminated and is cancelled qualified entering spray certified products warehouse.

Product grade is QT500-7, mechanical performance testing result: tensile strength＞500MPa, and surrender is slight＞320MPa, percentage elongation＞7%, cast product hardness reaches 170～230HBS; The metallographic structure testing result of product: nodularization rate＞80%, 4～6 grades of graphite sizes, ball light body 40～60% foundry goods do not have carbide.The dimensional accuracy of cast product meets the requirements.

The main technologic parameters of table 1 several embodiments of the present invention

The technical process of

embodiment

2,3,4,5 is no longer set forth with embodiment 1.

Claims

1. the casting method of robot base foundry goods, its step comprise mix sand, moulding, coremaking, core assembly, down core, mould assembly, furnace charge melting, the spheroidization and inoculation that taps a blast furnace handle, cast, cooling, unpacking, casting cleaning and product quality inspection; It is characterized in that:

In the core step, the employing automatic pug mixer carried out moulding and 3 cores of manufacturing after mixing the system furan resin self curing sand, when 3 cores of manufacturing, in each core, buries plug in advance under described coremaking, core assembly reached; Be fixed up 3 cores through pre-buried plug series combination during core assembly, form a big core;

Described furnace charge melting step comprises, the composition quality percentage of furnace charge: the pig iron 35%～45%, foundry return 35～45%, steel scrap 10%～30%; Melting adopts medium-frequency induction furnace to carry out the melting of iron liquid, and smelting temperature is 1480～1560 ℃;

The described spheroidization and inoculation treatment process of tapping a blast furnace comprises spheroidising and two steps of inoculated of silicon barium;

In the described cast operation, pouring temperature is controlled at 1380～1450 ℃.

2. the casting method of robot base foundry goods as claimed in claim 1; It is characterized in that the chemical composition mass percent of cast product is: C 3.4～3.7%, Si 2.4～2.8%, Mn 0.30～0.60%, P≤0.07%, S≤0.03%, RE 0.01～0.04%, Mg 0.03～0.06%, surplus Fe and inevitable impurity.

3. the casting method of robot base foundry goods as claimed in claim 1; It is characterized in that; The nodulizer total amount that described spheroidising step adds is 1.0～2.4% of the melting amount of tapping a blast furnace; The chemical composition mass percent of nodulizer is: Mg 5.0～7.0%, RE 1.0～3.0%, Si 38～48%, Ca 1.0～3.0% and Fe surplus, its granularity are 4～25mm.

4. the casting method of robot base foundry goods as claimed in claim 1; It is characterized in that; The addition of the silicon titanate innoculant that inoculated of described silicon barium is used is 0.5～1.2% of the melting amount of tapping a blast furnace; The chemical composition mass percent of silicon titanate innoculant is: Si 60～70%, Ca 0.8～2.2%, Al 1.0～2.0%, Ba 1.5～6.0% and Fe surplus, its granularity are 5～25mm.

5. the casting method of robot base foundry goods as claimed in claim 1 is characterized in that, before the mould assembly in the described mould assembly operation, places floamed ceramics filtrating piece in the sprue bottom.