CN86108146A - Casting method for compounding particles of tungstem cabonide with column surface - Google Patents

Abstract

Casting method for compounding particles of tungstem cabonide with column surface.Principal character is before the pouring liquid alloy, earlier tungsten carbide particle is placed the casting mold inner chamber and makes the casting mold rotation, and owing to action of centrifugal force, the tungsten carbide particle uniformly dispersing carries out the liquid alloy cast then at the casting mold inner surface in rotary course.In the casting process, casting mold rotates all the time.This method simply is easy to grasp, and tungsten carbide particle can be bonded in cylindrical outer surface securely, forms the composite bed of a surfacing, consistency of thickness, thereby obtains having the steel or the iron cylinder blank of closely knit casting carbon tungsten carbide particle surface composite layer.

Description

Casting method for compounding particles of tungstem cabonide with column surface

The invention belongs to centrifugal casting technique:

On the machine of many feeds processing, grain processing, use a kind of round roller that pushes machined object at large, to the service behaviour requirement of this garden roller be:

1, roller outer surface in garden should have very high hardness, and is not easy to wear.And require wear surface when work, to maintain certain roughness that is uneven always, to give full play to the material grasping ability of garden roller, guarantee the production efficiency of machine.

2, the garden roller should have bigger intensity and toughness on the whole, the compressive load that runs into when bearing work.

So such garden roller often adopts the structure of compound one deck cast tungsten carbide hard alloy particle on steel alloy Cylinder outer surface.

Adopt the prior art situation of complex method cast tungsten carbide hard alloy particle garden roller class product as follows:

A, welding method: casting carbon tungsten carbide particle is contained among the steel pipe of shutting at two ends, and this kind steel pipe carries out built-up welding with " oxygen one acetylene flame " or electric arc on the product surface as " welding rod ".This kind welding method can only make the compound carbonizing tungsten layer that obtains 0.75～1.5 millimeters thick on the product outer surface, and surface irregularity, see that Ji Feier P executes Wal Ci Kepufei " carbide alloy " Chinese industrial publishing house, 1963.432-433 page or leaf and strain state cemented carbide works " use of carbide alloy " metallurgical industry publishing house, 1973.

B, glue weldering method: with waterglass tungsten carbide particle directly is bonded at the surface of product, uses the oxy-acetylene flame area of heating surface, make the metal thawing on product surface.Tungsten carbide particle just can be deposited in the metal of this melting, then when metal solidifies again, just can cling tungsten carbide particle.The carbide layers compound with this method is very thin, and can only be used for the compound of small size, complex technical process.See strain state cemented carbide works " use of carbide alloy " metallurgical industry publishing house 1982.

C, with the molten metal casting:

The density of utilizing tungsten carbide particle itself is than the big characteristics of garden roller parent metal density, and utilizes the also higher characteristic of the fusing point of tungsten carbide own, and the manufacturing of garden roller matrix and the operation of compound carbonizing tungsten particle are combined.Promptly adopt centre spinning method, when the metal of cast garden roller matrix, in pouring basin, spread tungsten carbide particle, both are entered among the casting mold together.In the casting mold of rotation, the tungsten carbide particle that density is bigger is deposited on the surface of casting mold, makes the cast outer surface after solidifying be compounded with one deck tungsten carbide particle at last.Japan has proposed the patent of this method in nineteen eighty-two.The clear 57-118850 of day disclosure special permission communique (A).But the composite bed thickness on the cast outer surface that makes with this technology is difficult for evenly; Tungsten carbide particle then can be stayed the foundry goods middle part, and the processing subsequently of garden roller is met difficulty as having little time deposition; Tungsten carbide also easily with iron composition lyotrope and be melted, has destroyed the structure of tungsten carbide composite bed.

The method of compound carbonizing tungsten also has tungsten carbide coating casting infiltration (easily south etc. " casting infiltration is made the research of wearing composite material " " casting " No5 1985.13-18 page or leaf) again castingin tungsten carbide agglomerate method, spray fuse method etc. on this external steel, but they only are applicable to the compound of powdery tungsten carbide, and complex technical process can not be used for compound on the Cylinder product outer surface.

Purpose of the present invention and task thereof are to adopt the simplest process-centre spinning, the process of the process of compound carbonizing tungsten hard alloy particle and the garden of manufacturing roller matrix is combined together, utilize the high temperature of parent metal when pouring into a mould and cooling subsequently, tungsten carbide particle evenly is compounded on the outer surface of garden cylindrical roller securely.Make the parts service behaviour of making reach satisfied requirement.

Detailed content of the present invention:

According to the outside dimension of garden roller and length internal diameter and the length by about 1.5% shrinkage factor design centrifugal casting mould, centrifugal casting mould can be metal mold, metal coating or sand mold.The casting mold that makes is installed on the centrifugal casting machine with needing centring.When the garden roller of producing that diameter is less, length is short, can adopt horizontal cantilever centrifugal casting machine; And when the garden roller of producing that diameter is big, length is bigger, then can adopt horizontal drum type centrifugal casting machine.According to the size calculated weight of garden roller matrix, the alloy liquid of fusing matrix.Under this external thickness condition according to required tungsten carbide composite bed, weighing goes out tungsten carbide particle, and tungsten carbide particle can be 10 to 40 orders.Treat alloy liquid fusing, and be superheated to (the steel alloy speech be can be 1400～1600 ℃) after the uniform temperature, start centrifugal casting machine, make the casting rotation; Meanwhile, tungsten carbide particle is placed in the groove of channel section, the length of groove should be longer than casting mold slightly, make tungsten carbide particle on casting mold length, be laid in the channel section groove equably, the channel section groove is stretched among the casting mold by the hole, garden on the casting mold end cap, and slowly rotation makes tungsten carbide particle in the groove on the inner surface that is being sprinkling upon the rotation casting mold on the whole length of casting mold equably, particle rotates together in company with casting mold, forms uniform one deck casting carbon tungsten carbide particle layer at the casting mold inner surface.After the tungsten carbide particle in the U-lag has all been toppled over, take the channel section groove in the autotype away, casting mold continues rotation.

Then in the casting mold of rotation, put in pouring basin, the ditch of a U-shaped should be arranged in the pouring basin, will puzzle refractory lining on the inner surface of this pouring basin.By chance be a needed liquid alloy of foundry goods by toppling in the melting furnace, liquid alloy is contained among the casting ladle, be transported to the pouring basin rear portion of centrifugal casting machine, promptly the molten metal in the casting ladle is poured in the acceptance cup of pouring basin then, molten metal is along pouring basin, outlet stream by the pouring basin front end is being covered with on the casting mold inner surface of tungsten carbide particle, under action of centrifugal force, molten metal is except evenly spreading out soon on the total inner surface of casting mold, it also has the effect in slit between stronger infiltration tungsten carbide particle, therefore can before solidifying, penetrate whole tungsten carbide particle layer, the heating tungsten carbide.Because tungsten carbide has good wetability with the iron group metal of pouring into a mould in the alloy, the molten metal of being poured into a mould can closely contact with tungsten carbide surface.Under the molten metal action of high temperature, the iron in the molten metal can be formed low-melting compound with carbon and tungsten in the tungsten carbide, as contains Fe ₃C is about 3.7%, W is about 17%, all the other have only 1085 ℃ for the object fusing point of Fe, and contain Fe ₃C is about 1.4%, W about 28% all the other have only 1335 ℃ for the object fusing point of iron.So when the matrix alloy of cast garden roller is steel or iron, the tungsten carbide particle surface of high-melting-point (about 2700 ℃) just can produce a very thin melting zone, tungsten carbide is dissolved in the iron, formed transition zone with molten steel or iron liquid, in process with the after coagulation cooling, because the existence of this transition zone, tungsten carbide particle is bonded on the outer surface of garden roller securely, form the composite bed of a surfacing, consistency of thickness, thereby obtained having the steel of closely knit casting carbon tungsten carbide particle surface composite layer or the garden roller roll body blank of irony.

Main points of the present invention are:

A, in the raw material of composite casting tungsten carbide particle, needn't add any binding agent, flux or other material;

B, in order to control the degree of depth and the compound fastness of tungsten carbide particle layer of infiltration carbide layers of garden roller matrix alloy liquid well, can adjust the temperature of tungsten carbide particle before entering casting mold, its adjusting range is 100 ℃ to 300 ℃;

The selection of c, casting mold rotating speed can be calculated as follows:

$\mathrm{n=}\frac{\mathrm{55200}}{\sqrt{y^r}}$

N=casting mold rotating speed in the formula, (rev/min)

The severe of γ-casting of molten metal, (ox/ ²)

The interior pore radius of r-garden roller, (rice)

Wall as the orchard roller is thicker, can after pouring the casting mold rotating speed suitably be reduced.To prevent the generation in crack on the foundry goods.

D, the casting mold operating temperature before cast can be 250 ℃-320 ℃ (to metal mold and metal coating speeches), and the temperature of sand mold should be room temperature.

Can oversimplify the roller shell of the garden cylindricality ferroalloy of making surface recombination Talide particle with present technique.It is the simplest process in the present known relevant technologies.The fastness of tungsten carbide composite bed can with the coming to the same thing of welding method; The comparable welding method of thickness of composite bed big, thus the working life of garden roller can be improved.Present technique can be used for the garden roller manufacturing of the virtually any size of the ferroalloy base of need compound carbonizing tungsten particle on all feed processing machineries, the Cereals Processing Machines.

Embodiment:

The pelleter roll is the garden cylindrical parts, and external diameter is 182 millimeters, internal diameter is 135 millimeters, presses dress bearing and axle in the inside of this roller shell, is contained on the pelleter, feed is grabbed under this roll, dry feed is pressed in the hole of die sleeve, make the particle that obtains having certain degree of packing.

Need composite grain 10～40 purpose tungsten carbide particles on the roller shell outer surface of this roll, thickness is 2～5 millimeters, and to improve the wearability and the material grasping of roll, the matrix of roller shell is chromium, manganese, molybdenum low-alloy steel, to guarantee the certain resistance to compression destructive power of roll.

This roller shell is produced on horizontal centrifugal casting machine.Earlier tungsten carbide particle is heated to 1500 ℃, tungsten carbide particle is put into U-lag, stretch into rotating speed and be among 900 rev/mins the casting mold, the U-lag that progressively overturns is poured tungsten carbide on the casting mold inner surface into, is that 1500～1550 ℃ alloy molten steel pours among the casting mold with fusion temperature, molten steel infiltrates carbide layers under centrifugal action, the fusion tungsten carbide particle, then adjusting the casting mold rotating speed is 500 rev/mins, uses the water cooling casting mold.Molten steel solidification can take out foundry goods.

Claims (4)

1, casting method for compounding particles of tungstem cabonide with column surface, Casting Equipment can adopt centrifugal casting machine, horizontal cantilever centrifugal casting machine or horizontal drum type centrifugal casting machine, casting mold can adopt sand mold, metal mold or metal coating, it is characterized in that before the pouring liquid alloy, earlier tungsten carbide particle is put into the casting mold inner chamber and make the casting mold rotation.In rotary course, tungsten carbide particle is evenly distributed on the casting mold inner surface, and casting mold continues rotation, pouring liquid alloy then.

2, the described casting method of claim 1 is characterized in that the temperature of tungsten carbide particle before entering casting mold should be 100 ℃ to 300 ℃.

3, the described casting method of claim 1 is characterized in that the rotating speed of casting mold should be calculated as follows.

$\mathrm{n=}\frac{\mathrm{55200}}{\sqrt{y^r}}$

Wherein, n be rotating speed (rev/min) for casting of molten metal severe (ox/rice ²) be the interior pore radius (rice) of circle roller.

4, the described casting method of claim 1, the temperature of casting mold should be room temperature for sand mold before it is characterized in that pouring into a mould, and should be 250 ℃-320 ℃ for metal mold and metal coating.