A kind of bronze bearing
Technical field
The present invention relates to the technical field of bearing, particularly a kind of bronze bearing and preparation method thereof, the bronze bearing that the Bronze alloy bar that especially a kind of semi-solid state extrusion prepares is prepared into.
Background technology
Tin bronze alloys has higher mechanical property, good wear resistant corrosion resistant and low-temperature flexibility, be easy to machining, particularly phosphorous tinbronze, there is very high hardness, elasticity and wear resistance, in air, seawater, all there is higher erosion resistance, and be easy to welding, be widely used in the part bearing friction in machinery equipment, as bearing etc.
But the subject matter that tinbronze exists is that higher Theil indices can cause tin bronze alloys to become hard and crisp, plasticity is very poor, often cracks, the defect such as segregation in the course of processing of viscous deformation.Meanwhile, traditional tin bronze alloys also easily produces the casting flaw such as shrinkage cavity and segregation in the process of casting, and due to its high-melting-point and the usual casting pressure applied, the destruction for casting mold is also very serious.
Semi-solid-state metal technology is a kind of technology between liquid state, solid molding that 20 century 70s propose, it fills the advantages such as type is steady, product compactness is high, little to the thermal shocking power of mould, mechanical property is high, forming pressure is low owing to having, and is widely used in metal forming manufacture.Preparation semi-solid-state metal technology being used for copper alloy can solve traditional casting and manufacturing deficiency problem undoubtedly.
And the quality of semi solid slurry and processing and forming technology are subsequently all the keys determining bronze material performance.Because the fluidity of molten of bell metal own is poor, cause its low temperature castability not good, how to pass through the composition, the semi solid slurry stirring intensity that control bell metal, and follow-up plastic working technique etc. obtains the bronze material with excellent properties, remains the technical problem urgently studied and explore.Namely such as patent documentation CN101384386 provides a kind of raw material phosphor bell metal for casting of semi-molten, but it is only confined to provide alloy raw material, and follow-up technique is not related to, and containing a large amount of harmful alloying elements Pb in its composition, so also lower to the control overflow of semi solid slurry.Patent documentation JP6-234049 also provides a kind of semi-solid casting making method of bell metal, but it considers the problems such as the casting deterioration that too high Sn content brings, strictly the content of Sn is limited in less than 9%, and do not provide the temperature of suitable semi-solid casting, do not relate to the follow-up plastic working process of semi-solid casting yet.
Summary of the invention
Namely object of the present invention is the bronze bearing providing a kind of wear resistance, excellent in mechanical performance, and it is obtained by following preparation method:
First, Bronze alloy bar is prepared
One, prepare burden: by alloy target weight percent be 10-12Sn, 6-6.5Bi, 0.20-0.23P, 0.1-0.15Zr, 0.05-0.09Zn, 0.01-0.02Fe, 0.01-0.02Ni, surplus be Cu and inevitably impurity take raw material, the total content of Zn+Fe+Ni is less than 0.1, the powder of described raw material is purity to be 99.99% oxygen free copper and purity be each alloying element of 99.9%;
Two, melting: the raw material prepared is carried out melting under air atmosphere in high frequency furnace, guarantee that melt liquid level is covered completely by charcoal in heat fused process, nickel powder and iron powder is added after temperature rises to 1400-1450 DEG C, be incubated after 2-3 minute, zirconium powder is added after continuing to be warming up to 1580-1650, insulation 5-10 minute, bismuth meal is added after being cooled to 1320-1350 DEG C subsequently, insulation 5-10 minute, glass putty is added after continuing to be cooled to 1280-1300 DEG C, insulation 15-20 minute, finally be cooled to 1200-1250 DEG C and add phosphorus powder, and be incubated 5-10 minute, through check and finely tune bath composition qualified after complete melting,
Three, the preparation of semi solid slurry: by the curved channel 3 of bell metal melt by being made up of agitator and water cooler, to obtain semi solid slurry, wherein said agitator 1 is be the periphery of 180-200 millimeter with detent projection, diameter, and described water cooler 2 has the cooling arc surface arranged with the outer circumference surface concentric gap of described agitator, described arc surface is 1/6 circumference, the height of described detent projection is 3-4 millimeter, space width is 4-5 millimeter, the distance in described gap is 8-9 millimeter, and the speed of rotation of described agitator is 180-200rpm;
Four, extrusion moulding processing: semi solid slurry is injected the extrusion mould through being preheating to 830-850 DEG C, maintain the temperature of semi solid slurry at 850-880 DEG C, carry out extrusion moulding processing with the extrusion ratio of the extrusion speed of 35-40mm/s, 10-15, obtain Bronze alloy bar;
Five, anneal: the bar extruded is cooled to 420-450 DEG C with the speed of 20-25 DEG C/s, after insulation 2.5-3h, air cooling of coming out of the stove, to room temperature, obtains Bronze alloy bar.
Subsequently, bar is processed as bearing products:
One, Bronze alloy bar is implemented to be drawn to finished product desired size through cold drawing equipment;
Two, by machining, Bronze alloy bar is shaped to bronze bearing product.
As preferably, described alloy target weight percent is 11Sn, 6.2Bi, 0.21P, 0.13Zr, 0.07Zn, 0.02Fe, 0.02Ni, surplus are Cu and inevitably impurity takes raw material;
As preferably, the distance in described gap is 9 millimeters.
As preferably, the speed of rotation of described agitator is 190rpm.
As preferably, extrusion moulding processing maintains the temperature of semi solid slurry at 860 DEG C.
As preferably, the extrusion speed of extrusion moulding processing is 38mm/s, and extrusion ratio is 12.
The invention has the advantages that: the proportioning that have adjusted each alloying element, while larger Theil indices, add the bismuth of larger content to replace lead, and with the addition of the alloying element of the trace such as Zn, Fe, Ni in right amount, by controlling melting technology, Melt Stirring speed and passing through the parameters such as flow, extrusion temperature, extruded velocity and extrusion ratio, be aided with the thermal treatment process matched again, obtain the Bronze alloy bar of excellent performance.
Accompanying drawing explanation
Fig. 1 is the schematic diagram of semi-solid slurry preparation device of the present invention.
Embodiment
Embodiment 1-3, and comparative example 1#-11#:
One, prepare burden: take raw material with the alloy target weight percent shown in table 1, the powder of described raw material is purity to be 99.99% oxygen free copper and purity be each alloying element of 99.9%;
Two, melting: the raw material prepared is carried out melting under air atmosphere in high frequency furnace, guarantee that melt liquid level is covered completely by charcoal in heat fused process, nickel powder and iron powder is added after temperature rises to 1430 DEG C, be incubated after 2 minutes, zirconium powder is added after continuing to be warming up to 1600, be incubated 10 minutes, bismuth meal is added after being cooled to 1340 DEG C subsequently, be incubated 10 minutes, add glass putty after continuing to be cooled to 1280 DEG C, be incubated 18 minutes, be finally cooled to 1220 DEG C and add phosphorus powder, and be incubated 5 minutes, through check and finely tune bath composition qualified after complete melting;
Three, the preparation of semi solid slurry: by the curved channel of bell metal melt by being made up of agitator and water cooler, to obtain semi solid slurry, wherein said agitator is be the periphery of 180 millimeters with detent projection, diameter, and described water cooler has the cooling arc surface arranged with the outer circumference surface concentric gap of described agitator, described arc surface is 1/6 circumference, the height of described detent projection is 4 millimeters, space width is 4 millimeters, the distance in described gap is 8 millimeters, and the speed of rotation of described agitator is 180rpm;
Four, extrusion moulding processing: semi solid slurry is injected through being preheating to the extrusion mould of 830 DEG C, the temperature maintaining semi solid slurry at 850 DEG C, with the extrusion speed of 35mm/s, 10 extrusion ratio carry out extrusion moulding processing, obtain Bronze alloy bar;
Five, anneal: the bar extruded is cooled to 440 DEG C with the speed of 22 DEG C/s, after insulation 2.5h, air cooling of coming out of the stove, to room temperature, obtains Bronze alloy bar product.
Can know by inference to draw a conclusion by the result of table 1:
The content of Sn should be strict controlled between 10-12%, too high Sn content can affect the extrusion moulding processing characteristics of alloy, thus worsen intensity and the tensile property of final bar, but too low Sn content will have a strong impact on the flowing property of semi solid slurry, thus cause the extrusion performance of bar to worsen, also make its intensity wretched insufficiency.
The content of Bi should control the scope at 6-6.5%, and too high Bi content can cause the deterioration of extrusion performance because of problems such as the setting expansions of Bi, but Bi content is too low, is unfavorable for the performance such as wear-resistant of material, does not have the effect replacing harmful element lead.
P is the important Addition ofelements of tinbronze, in alloy system of the present invention, the content of P should more than 0.23%, otherwise will the wretched insufficiency of tensile property be caused, but the content of P should at least more than 0.2%, because need to put forward heavy alloyed mobility to obtain the casting of semi solid slurry, the processing characteristics such as shaping by P.
Zr both can promote alloy system melt flow property with P is collaborative, also alloy plays the effect of precipitation strength to a certain extent, its content is too low does not have the effect improving mobility and the deficiency causing semi solid slurry extrusion moulding performance, too high, can cause the wretched insufficiency of molded plastic.
The interpolation of trace alloying element Zn, Fe, Ni obviously can improve the intensity of alloy system, but considers that excessive interpolation may cause the machine-shaping property of material to worsen, and therefore should control its total content and be less than 0.035%.
Table 1
Embodiment 4-5, and comparative example 12#-21#, the composition of alloy is identical with embodiment 2, stirring velocity, by flow, procession parameters etc. see table 2.
Can be known by inference by the result of table 2:
Stirring velocity has material impact for the structure property of Copper alloy bar, too low stirring velocity can make the effect of stirring insufficient, and be difficult to play enough crystal grain thinnings, improve the effects such as mobility, thus cause extrusion performance subsequently to worsen, too high stirring velocity is then likely involved in gas and causes defect, thus affects materials microstructure and performance.Comparatively reasonably stirring velocity is 180-200rpm.
Clearance distance is the direct reaction of melt flow and cooling degree, too small clearance distance makes melt too low and cause the undercooling of melt and affect mobility and the extrusion performance of semi solid slurry by the speed of water cooler, excessive clearance distance then can cause a large amount of outflow of melt and cause cooling insufficient, thus affects the extrusion performance of semi solid slurry.Comparatively reasonably clearance distance is 8-9 millimeter.
The processing parameter extruded is the important factor directly determining performance test, extrusion temperature is too low, extrusion speed is too fast or extrusion ratio is excessive, capital causes the sharply increase of extruding load, thus cause the deterioration of the difficulty of processing and the performance of product, and extrusion temperature is too high, extrusion speed is too low or extrusion ratio is too small, then can not to play in enough suppression bars the defects such as shrinkage cavity, and cause the density unevenness of tin and low.Consider, extrusion temperature preferably controls at 850-880 DEG C, and extrusion speed controls at 35-40mm/s, and extrusion ratio controls between 10-15.
Table 2
By above-mentioned Bronze alloy bar, be prepared as bearing products by following steps:
One, Bronze alloy bar is implemented to be drawn to finished product desired size through cold drawing equipment;
Two, by machining, Bronze alloy bar is shaped to bronze bearing product.
To sum up, the present invention is by the proportioning of adjustment alloying element, and control melting technology, Melt Stirring speed and pass through the parameters such as flow, extrusion temperature, extruded velocity and extrusion ratio, be aided with the thermal treatment process matched again, obtain the Bronze alloy bar of excellent performance, and with it for starting material have prepared the bearing products of excellent performance.