CN103978138B - A kind of bearing casting billet surface speed is cold-controls heat to roll over and organize ameliorative way - Google Patents

Abstract

The present invention relates to a kind of bearing casting billet surface speed cold-control heat roll over organize ameliorative way, comprise following content: (1) casting base: refined molten steel is poured into spun cast pipe in horizontal centrifuge, depanning 1200 DEG C ~ 1250 DEG C time after solidification of molten steel completes, rolling ratio and hot pipe internal-and external diameter is determined successively according to bearer ring size, with steel pipe blanking machine, by bearer ring height, sawing is carried out to hot pipe, obtain bearing strand; (2) casting billet surface forces speed cold: carry out surface to strand surfaces externally and internally spray normal temperature water smoke and force cooling, make strand surfaces externally and internally fast cooling to 800 ~ 850 DEG C, and heart portion temperature remains on 950 ~ 1050 DEG C; (3) control hot rolling: fast for surface chill casting base is carried out hot rolling immediately, control rolling feed speed according to rolling ratio and bearer ring Sizes.The present invention can promote the effective refinement of the thick tissue in bearing strand heart portion and global tissue homogenising, improves product structure and properties uniformity, and can reduce technological process, reduce energy consumption, raise the efficiency.

Description

A kind of bearing casting billet surface speed is cold-controls heat to roll over and organize ameliorative way

Technical field

The present invention relates to bearing mnanufacture technology, be specifically related to a kind of bearing casting billet surface speed cold-control heat roll over organize ameliorative way.

Background technology

Bearing is Mechanical Fundamentals part, has extensive important application at many industrial circles.The matrix of bearing is annular bearing ring (abbreviation bearer ring), it to the performance of bearing and the life-span most important.At present, in bearer ring production, most widely used technique is blank after heat rolling forming, namely first forges and rolles over afterwards.This technique can obtain the bearing forging stock of even as-forged microstructure, thus ensures hot rolling forming ring performance, but blank operation is many, efficiency is low, core material waste is many, and therefore energy consumption is high, stock utilization is low.Directly carry out hot rolling by casting acquisition ring-shaped casting blank and namely cast rolling shaping, comparing forging shaping, shorten technological process, reduce energy consumption, improve stock utilization, is a kind of ring-shaped work pieces low-consumption high-efficiency new technology, has started at present to be researched and developed.But compare the even as-forged microstructure of forging stock, the thick inequality of as-cast structure of strand, exists the defects such as pore, shrinkage porosite, segregation more, need to be improved by hot rolling to eliminate, otherwise serious genetic risk can be produced to ring performance.Due to foundry method features, the defects such as the defect(ive) structure of strand and internal porosity focus mostly in ring base heart portion, and hot rolling has inhomogeneous deformation feature, ring base heart portion is stagnant zone, deflection is little, and tissue improves weak effect, makes to cast to roll over that shaping ring exists that surface texture is tiny more and core structure is thick and the problem that shrinkage porosite, hole are left over, finally cause ring mechanical property distribution uneven, cannot instructions for use be met.Therefore, causing continuous casting billet structure can not obtain effective improvement due to casting and hot rolling process characteristic, is the Main Bottleneck that forming technology application in high-performance bearing ring manufactures is rolled in restriction casting.

Summary of the invention

For above-mentioned present situation, the present invention proposes a kind of bearing casting billet surface speed, and cold-control heat is rolled over and is organized ameliorative way, by controlling strand temperature distribution state and hot rolling deformation parameter, effectively can increase and promote the distortion of hot rolling process strand heart portion and structure refinement, improve casting blank deformation uniformity, realize even tissue and improve.

For achieving the above object, technical solution of the present invention is: a kind of bearing casting billet surface speed is cold-and controls heat to roll over and organize ameliorative way, it is characterized in that comprising following specific implementation step:

(1) base is cast: pour refining liquid steel (molten steel) in horizontal centrifuge spun cast pipe, 1200 DEG C ~ 1250 DEG C depannings after molten steel (molten steel) has solidified, obtain hot pipe (to explain: hot pipe inside/outside diameter size is cast blank size, be related to rolling deflection, so should provide, tube blank size controls to obtain by casting die); The internal diameter of hot pipe, outside dimension are d ₀, D ₀, determine by following formula according to bearer ring size:

$D_0=\frac{(D-d)K^2+(D+d)}{2K},$ $d_0=\frac{-(D-d)K^2+(D+d)}{2K}---\left(1\right)$

Wherein, d, D are respectively the inside and outside diameter of bearer ring; K is rolling ratio, is bearing strand sectional area and the ratio of bearer ring sectional area; For making strand rolling process produce fully distortion thinning microstructure and control inhomogeneous deformation degree, rolling ratio can by choosing as follows:

K＝1.2+0.027H-1.9×10 ^-4H ²(2)

Wherein, H=(D-d)/2, H is the wall thickness of bearer ring;

With steel pipe blanking machine, bearer ring height sawing is pressed to hot pipe, obtain bearing strand;

(2) bearing casting billet surface forces speed cold: carry out surface to bearing strand surfaces externally and internally spray normal temperature water smoke and force cooling, make strand surfaces externally and internally fast cooling to 800 ~ 850 DEG C (and heart portion temperature remains on 950 ~ 1050 DEG C);

(3) control hot rolling: fast for surface chill casting base is carried out hot rolling immediately, in order to make, rolling process strand produces fully, uniform plastic deformation, and rolling feed speed is determined by following formula:

$v=k\frac{2n_d{R}_d{\left(\arctan \mathrm{\μ}\right)}^2}{R_0{(\frac{1}{R_d}+\frac{1}{R_m})}^2}(\frac{1}{R_d}+\frac{1}{R_m}+\frac{1}{R_0}-\frac{1}{r_0})---\left(3\right)$

Wherein, k is constant, gets 0.2 ~ 0.5; r ₀=d ₀/ 2, R ₀=D ₀/ 2, be respectively bearing strand inside radius, outer radius; R _dand R _mbe respectively the radius of clean-up of drive roll and core roller; n _dfor drive roll rotating speed; μ is coefficient of friction.

The invention has the beneficial effects as follows: by forcing speed cold to casting billet surface, increase casting billet surface and the heart portion temperature difference, make that areal deformation drag sharply increases and heart portion resistance of deformation is substantially constant, plastic zone easier centripetal portion expansion in hot rolling and increase the strain of heart portion and strain rate, be conducive to heart portion as-cast structure change and shrinkage porosite, hole forging conjunction.Selected by reasonable rolling ratio and rolling speed, control strand inhomogeneous deformation, improve deformation uniformity, make strand zones of different tissue obtain even refinement, the thin even Tissue distribution of final acquisition, improve product structure property uniformity, ensure bearer ring mechanical property.In addition, utilize cast tube waste heat to carry out rolling, eliminate heating link, shorten technological process, reduce energy consumption, improve efficiency.

Detailed description of the invention

In order to understand the present invention better, illustrate content of the present invention further below in conjunction with embodiment, but content of the present invention is not only confined to the following examples.

Embodiment 1:

For certain GCr15 bearer ring, its external diameter is 425mm, internal diameter is 355mm, highly for 30mm, its bearing casting billet surface speed is cold-and controls heat to roll over and organize ameliorative way, realize as follows:

(1) base is cast: pour GCr15 molten steel after refining into spun cast pipe in horizontal centrifuge, 1200 DEG C of depannings after solidification of molten steel completes, obtain hot pipe.Be 1.9 than computing formula and bearer ring size determination rolling than K according to rolling of the present invention.Then hot pipe outer diameter D is determined according to the present invention's hot pipe inside/outside diameter size computing formula, bearer ring size and rolling ratio ₀for 212.81mm, internal diameter d ₀for 102.41mm.With steel pipe blanking machine, height 30mm bearing strand is obtained to hot pipe sawing, now casting blank surface temperature about 1100 DEG C.

(2) casting billet surface forces speed cold: carry out surface to strand surfaces externally and internally spray normal temperature water smoke and force cooling, make its surface temperature be down to about 800 DEG C fast.

(3) control hot rolling: the surface cold rear strand of speed is put into Ring Rolling Machine, in order to make, rolling process strand produces fully, uniform plastic deformation.According to rolling feed speed computing formula, in the present embodiment, k gets 0.2, r ₀=d ₀/ 2, R ₀=D ₀/ 2 are respectively 69.38mm and 135.88mm, R _d, R _mbe respectively 285mm and 55mm, n _dfor 1.2r/s; μ gets 0.3, calculates and determines that rolling feed speed is 2.43mm/s.

To the present invention surface speed cold-control heat to roll over bearer ring and roll over forming axis carrier ring and carry out tissue with conventional casting and compare.Respectively to two kinds of method lower bearing ring outer surfaces, heart portion, inner surface sampling, carry out crystallite dimension test and comparison, result is as shown in table 1: the present invention surface speed is cold-and controls heat to roll over bearer ring heart portion crystallite dimension and roll over bearer ring than conventional casting and reduce 29.92%, overall crystal grain nonunf ormity declines 35.97%.

Table 1 bearer ring each region crystallite dimension test result

Embodiment 2:

For certain 42CrMo bearer ring, its external diameter is 320mm, internal diameter is 260mm, highly for 35mm, its bearing casting billet surface speed is cold-and controls heat to roll over and organize ameliorative way, realize as follows:

(1) base is cast: pour 42CrMo molten steel after refining into spun cast pipe in horizontal centrifuge, 1250 DEG C of depannings after solidification of molten steel completes, obtain hot pipe.Be 1.84 than computing formula and bearer ring size determination rolling than K according to rolling of the present invention; Then determine that hot pipe internal-and external diameter is 212.81mm, internal diameter is 102.41mm according to the present invention's hot pipe inside/outside diameter size computing formula, bearer ring size and rolling ratio, cast tube steel pipe blanking machine sawing after depanning is obtained height 35mm bearing strand, now casting blank surface temperature about 1150 DEG C;

(2) casting billet surface forces speed cold: carry out surface to strand surfaces externally and internally spray normal temperature water smoke and force cooling, make its surface temperature be down to about 850 DEG C fast.

(3) control hot rolling: the surface cold rear strand of speed is put into Ring Rolling Machine, in order to make, rolling process strand produces fully, uniform plastic deformation.According to rolling feed speed computing formula, in the present embodiment, k gets 0.5, r ₀=d ₀/ 2, R ₀=D ₀/ 2 are respectively 51.205mm and 106.405mm, R _d, R _mbe respectively 285mm and 55mm, n _dfor 1.2r/s; μ gets 0.3, calculates and determines that rolling feed speed is 6.17mm/s.

To the present invention surface speed cold-control heat to roll over bearer ring and roll over forming axis carrier ring and carry out tissue with conventional casting and compare.Respectively to two kinds of method lower bearing ring outer surfaces, heart portion, inner surface sampling, carry out crystallite dimension test and comparison, result is as shown in table 2: the present invention surface speed is cold-and controls heat to roll over bearer ring heart portion crystallite dimension and roll over bearer ring than conventional casting and reduce 27.04%, overall crystal grain nonunf ormity declines 39.05%.

Table 2 bearer ring each region crystallite dimension test result

Above-mentioned example illustrates, adopt the inventive method gained bearer ring core structure thinning effect obvious, and global tissue is more evenly distributed, and illustrates that the present invention can effectively improve bearing continuous casting billet structure.

The technology of the present invention method is also applicable to the bearer ring of other material, and its method is identical with above-mentioned example, and effect is also identical, in this not particularize embodiment.

Claims (1)

1. bearing casting billet surface speed cold-control heat roll over a method for organizing, it is characterized in that comprising following specific implementation step:

(1) base is cast: refining liquid steel is poured into spun cast pipe in horizontal centrifuge, 1200 DEG C ~ 1250 DEG C depannings after solidification of molten steel completes, obtain hot pipe; The internal diameter of hot pipe, outside dimension are d ₀, D ₀, determine by following formula according to bearer ring size:

$D_0=\frac{(D-d)K^2+(D+d)}{2K},d_0=\frac{-(D-d)K^2+(D+d)}{2K}---\left(1\right)$

Wherein, d, D are respectively the inside and outside diameter of bearer ring; K is rolling ratio, is bearing strand sectional area and the ratio of bearer ring sectional area; For making strand rolling process produce fully distortion thinning microstructure and control inhomogeneous deformation degree, rolling ratio can by choosing as follows:

K＝1.2+0.027H-1.9×10 ^-4H ²(2)

Wherein, H=(D-d)/2, H is the wall thickness of bearer ring;

With steel pipe blanking machine, bearer ring height sawing is pressed to hot pipe, obtain bearing strand;

(2) bearing casting billet surface forces speed cold: carry out surface to bearing strand surfaces externally and internally spray normal temperature water smoke and force cooling, make strand surfaces externally and internally fast cooling to 800 ~ 850 DEG C;

(3) control hot rolling: fast for surface chill casting base is carried out hot rolling immediately, in order to make, rolling process strand produces fully, uniform plastic deformation, and rolling feed speed is determined by following formula:

$v=k\frac{2n_d{R}_d{\left(\arctan \mathrm{\μ}\right)}^2}{R_0{(\frac{1}{R_d}+\frac{1}{R_m})}^2}(\frac{1}{R_d}+\frac{1}{R_m}+\frac{1}{R_0}-\frac{1}{r_0})---\left(3\right)$

Wherein, k is constant, gets 0.2 ~ 0.5; r ₀=d ₀/ 2, R ₀=D ₀/ 2, be respectively bearing strand inside radius, outer radius; R _dand R _mbe respectively the radius of clean-up of drive roll and core roller; n _dfor drive roll rotating speed; μ is coefficient of friction.