CN105014077B - The preparation method of powder metallurgical gear, sprocket wheel - Google Patents

Abstract

The preparation method of a kind of powder metallurgical gear, sprocket wheel, step：Carbon, iron, chromium, molybdenum, copper, nickel are mixed into a point powder, carbon by following mass percent：0.1~1.5%, copper：0~4%, nickel：0~5%, molybdenum：0~2%, chromium：0.0~18%, no more than 2% inevitable impurity, iron：Surplus；Above-mentioned mixed powder is more than on 400MPa press in pressure and is pressed into density for 6.6~7.4g/cm³Tooth（Chain）Take turns green compact；Then it is sintered at 1000 DEG C~1350 DEG C, sintering time is 5~180 minutes；Annealed in non-oxidizing atmosphere, 750~1080 DEG C of annealing temperature, 5~200 minutes time；Reequiped and uniformly extruded on press by single lead screw ex truding briquetting machine or sizing rolling machine, amount of compression is more than the 2% of the difference of outside circle and root diameter；Heat treatment is finished product.Manufacture craft of the present invention is simple, and tooth is made（Chain）Take turns precision height, surface smoothness good, reduce production cost, improve production efficiency, compared with prior powder metallurgy technique, product density is higher, and surface densification is realized substantially.

Description

The preparation method of powder metallurgical gear, sprocket wheel

Technical field

The invention belongs to powder metallurgical technology, especially a kind of ferrous based powder metallurgical gear, the preparation method of sprocket wheel.

Background technology

Tooth（Chain）The important spare part as transmission system is taken turns, traditional method is all by being machined shaping.Machine The tooth of tool processing（Chain）The current main machining method of wheel has steel directly by the method shaping of machining and by cold Extrusion molding.The method process of machining is longer, and utilization rate of raw materials is relatively low, about between 40~60%, product cost compared with Height, uniformity is poor, and production efficiency is relatively low, it is difficult to meet the requirement good to high-volume uniformity.

And use the method for cold extrusion to shape, warm forging base is generally required, then cold-extrusion shaping.Forging's block dimension precision Height, good dimensional uniformity, any surface finish, the profile accuracy of internal gear are high, gear profile is clear, outer surface machining allowance compared with It is few；Stock utilization reaches 90% or so；Warm Forging Die (cavity plate) life-span 5000~6000, and cold extrusion die (punch-pin) longevity Life 8000~10000；The appearance of cold-extruded part is bright and clean, and machine-finish allowance is few, substantially reduces subsequent mechanical labor content, With short production cycle, production efficiency is high.But the loss of the method mould of cold extrusion is larger, cost is also difficult to meet automobile, motorcycle Deng the requirement of industry.

Powder metallurgy is to produce high intensity and effective technique of complex shape part.Also occur in that at present and use powder metallurgy Technique replaces traditional manufacturing process to prepare the Chinese invention patent of gear, such as Patent No. CN201110323618.8《One Plant powder metallurgy start chainwheel, gear》, once compressing using powder metallurgical technique, its raw material weight percentage is：Iron： 95.5~98%；Carbon：0.3~1.2%；Copper：0.7~2%；Manganese sulfide：0.1~0.5%；Zinc stearate：0.3~1.2%.Also There is Patent No. CN201310248909.4 Chinese invention patent《A kind of powder metallurgical gear and preparation method thereof》, its feature It is：It is made from the following raw materials in parts by weight：Iron powder 96-99, molybdenum powder 1.2-1.4, aluminium powder 2.1-2.4, carborundum 0.8-1.0, Stearic acid 2.3-2.6, ATBC 1.2-1.5, Be0.2-0.3, Pb0.1-0.2, Mg0.9-1.2, La0.1-0.15, carbon SiClx 1.2-1.4, niobium carbide 0.3-0.4, Nb₂O₅0.2-0.3、SnO₂0.5-0.6, the molybdenum 1.0-1.2 of boronation two, dispersant 2-3. It changes raw material proportioning, can strengthen the toughness and intensity of powder metallurgical gear.Current powder metallurgical technique can give birth to Output density is more than 7.4g/cm³Part, but for more than 7.6g/cm³Part, current main manufacturing technology includes note Penetrate shaping, power forging.And the level of density of repressing and re-sintering technology is substantially in 7.4~7.6g/cm³Between.In addition, also surface Densification technology, makes profiled parts pass through cross rolling（Rolling）Realize the local densified of gear surface.

PM technique 2005 year volume 23 first phase page 62 describes surface gear densification technology（Surface compact Change --- a kind of effective ways for improving sintered gear(s) performance）.This is a kind of method for realizing that the flank of tooth is local densified.It is main logical The Problem of Failure of local densified solution gear is crossed, because most of failure is surface contact fatigue, improving density can improve Fatigue behaviour.

In heat treatment industry case-carbonizing, Surface heat-treatent as you know（High frequency or laser heat treatment）, firmness outside （Carbon content）Height, wearability is good, centre hardness（Carbon content）It is low, good toughness.Powdered metal parts are due to the presence of hole, surface The difference that contact fatigue strength is often processed compared with casting steel.Handled by surface densification, the surface of teeth portion contact is nearly reached entirely It is fine and close.

After surface densification, teeth portion is pore-free surface and porous center portion；What only superficial density was high bears applied stress, It is of relatively low cost；Sintered gear(s) is under the repeat-rolling of roller mould, and tooth form and precision increase.

The dimensional accuracy of gear can be further improved by surface densification.Surface densifying depth, can more than 0.7mm To increase substantially the surface contact fatigue stress of gear.In addition, the surface roughness of gear reaches the standard of " minute surface ", As a result noise is lower when gear is run.The non-porous gear in this surface is after suitable heat treatment, its bending fatigue strength The level of 8620 carburizing steel is fully achieved with contact fatigue strength.Manufacture above-mentioned helical gear process as follows：Shaping（High density）； Sintering（Control cooling velocity）；Machining；Surface densification；Heat treatment（Control heat treatment deformation）.

The advantage of surface densification is as follows：Teeth portion imporosity；Good surface；Increase wearability；Reduce noise；Improve resistance to Corrosivity；Gear size precision is high；Improve the fatigue properties of part.But surface densification technology is only applicable to external gear etc. A small number of parts, application is relatively limited.In addition, the part for carbon content more than more than 0.3%, because hardness is higher, surface Rolling（Densification）More difficult, superficial density is difficult to be lifted.

Above-mentioned technology has some limitations.One-shot forming is sintered due to lightweight materials such as lubricant and graphite Influence, density refractory is to improve.For injection molding technique, the responsible part of shape is only applicable to, and for simple shape size Larger part cost performance is too poor.The precision of power forging is relatively low, and mould loss is larger.

For repressing and re-sintering technique, product density is in 7.4~7.6g/cm³Between.In order to avoid or slow down Carbon diffusion, Retain more ferrites, general pre-sintering temperature is usually 780~850 DEG C or so, with the lifting of pre-sintering temperature, carbon Diffusion increases, and the tissue ratio such as pearlite is dramatically increased.As content of pearlite in alloy increases, the pressure increase pressed again, while mould Loss also increases.

Accordingly, it would be desirable to develop new technique, the precision and density issue of powder metallurgy product are solved, this is for improving powder Metallurgical tooth（Chain）The local density of the density of wheel, the especially flank of tooth, for powder metallurgy toothed（Chain）The application of wheel has heavy to closing The meaning wanted.

The content of the invention

The technical problems to be solved by the invention are to provide a kind of powder metallurgical gear, chain for the above-mentioned state of the art The preparation method of wheel, preparation technology is simple, and obtained gear, sprocket wheel precision are high, surface smoothness is good, effectively eliminate forging During mould is also easy to produce the problem of cracking due to carrying out at high temperature, so as to reduce production cost, improve production Efficiency.

The present invention solve the technical scheme that is used of above-mentioned technical problem for：A kind of preparation of powder metallurgical gear, sprocket wheel Method, it is characterised in that comprise the following steps：

1）Raw material is got out, carbon, iron, chromium, molybdenum, copper, nickel are mixed into a point powder by following mass percent, matches and is Carbon：0.1~1.5%, copper：0~4%, nickel：0~5%, molybdenum：0~2%, chromium：0~18%, the inevitable impurity no more than 2%, Iron：Surplus；

Wherein, chromium, molybdenum, copper, nickel are added with ferroalloy or foundry alloy form, and carbon is added with form of graphite, then adds matter Measure the lubricant that degree is 0.1~1%；

2）Above-mentioned mixed powder is more than in pressure the gear that density is 6.6~7.4g/cm3 is pressed on 400MPa press Or sprocket wheel green compact；

3）Said gear or sprocket wheel green compact are sintered in 1000 DEG C~1350 DEG C of temperature, time of sintering for 5~ 180 minutes；

4）Annealed in non-oxidizing atmosphere, annealing temperature is 750~1080 DEG C, 5~200 points of soaking time of annealing Clock is annealed, and is less than 0.3% and the gear or sprocket wheel of molybdenum, chromium, nickel and copper alloy total content less than 2%, lehr attendant for carbon content Sequence can be alternatively.

5）Extruding：Extruded on the press reequiped by single lead screw ex truding briquetting machine or sizing rolling machine, amount of compression L2 is more than tooth top 2%, i.e. L2 >=(da-d)/2 × 2% of the difference of circle and root diameter, for internal gear, then amount of compression L2 is more than root circle and tooth The 2% of the difference of outside diameter circle, then L2 >=(d-da)/2 × 2%, wherein, da is tip diameter, and d is root diameter；

6）Heat treatment：Hardening heat is 750~1250 DEG C, is incubated 10~240 minutes, and temperature is 150~600 DEG C, Insulation 5~200 minutes, being more than 0.4% gear or sprocket wheel for carbon content after sintering can be heat-treated using high frequency or intermediate frequency, heat 0.2~5mm of case depth of processing, temperature is 150~600 DEG C, is incubated 5~200 minutes, or uses high frequency or intermediate frequency Induction tempering.

As an improvement, the step 1）Lubricant and graphite etc. added using bonding processing mode.

As an improvement, the step 2）Compacting uses warm-pressing formation or mould thermoforming to reduce pressing pressure or enter one Step improves green density, and the pressing pressure of press is 600Mpa.

As an improvement, the step 3）Sintering be carried out in vacuum sintering furnace either based on nitrogen, the ratio of hydrogen Example is progress in 1~75vol% sintering furnace.

Improve again, the step 4）After annealing, from annealing temperature to 300 DEG C cooling velocity be less than 1.5 DEG C/S.

Improve again, the step 3）, step 4）Sintering and annealing two procedures can unite two into one, after sintering terminates will Temperature control is incubated in annealing temperature, and room temperature is dropped to according to the time and cooling requirement of annealing.

Further improve, the step 5）Extrude and extruded or non-homogeneous extruding to be uniform, in extrusion process, for external tooth Speech, extrusion die former is at least divided into two parts of guide section and sizing section, for internal tooth, plug be at least divided into guide section and Two parts of sizing section.For amount of compression L2, it can be evenly distributed in toothed peripheral, can also non-uniform Distribution in tooth form Periphery, the form such as concrete form has tooth top region not extrude, tooth top tooth root region is not extruded and tooth root region is not extruded, for Now amount of compression L2 is defined as the deflection of maximum, L2 >=(da-d)/2 × 2%.

Further improve, the step 6）After heat treatment terminates, also increase bead, further to improve the tired of product Labor intensity and superficial density.

Compared with prior art, the advantage of the invention is that：Increase the process of extruding, substantially increase the density of product, Especially appearance surface density so that obtained gear or sprocket wheel precision is high, surface smoothness is good, effectively eliminates forging process In mould is also easy to produce the problem of cracking due to carrying out at high temperature, so as to reduce production cost, improve production efficiency. Manufacture craft of the present invention is simple, and compared with prior powder metallurgy technique, the density of product is higher, and the density in teeth portion region can surpass Cross 7.60g/cm³, close to the level of power forging, and surface relative density can reach more than 99%, and surface compact is realized substantially Change.

Brief description of the drawings

The structural representation for the gear that Fig. 1 is prepared for the present invention；

Fig. 2 is uniform extruding amount of compression schematic diagram；

Fig. 3 is non-homogeneous extruding amount of compression schematic diagram（Tooth top is not extruded）；

Fig. 4 is non-homogeneous extruding amount of compression schematic diagram（Tooth top tooth root is not extruded）；

Fig. 5 is non-homogeneous extruding amount of compression schematic diagram（Tooth root is not extruded）；

Fig. 6 is extruding former schematic diagram；

Fig. 7 is extruding former top view；

Fig. 8 is extruding plug schematic diagram；

Fig. 9 is pattern before teeth portion extruding；

Figure 10 is pattern after teeth portion extruding；

Figure 11 is pattern before flank extruding；

Figure 12 is pattern after flank extruding；

Figure 13 is pattern after tooth top extruding；

Figure 14 is pattern after tooth root extruding；

Figure 15 is flank of tooth pattern after heat treatment；

Figure 16 is heat treatment backgear center portion pattern；

Figure 17 is flank of tooth pattern after heat treatment；

Figure 18 is heat treatment backgear center portion pattern.

Embodiment

The present invention is described in further detail below in conjunction with accompanying drawing embodiment, following percentage is quality percentage Than.

Embodiment one:

1. the mixed powder of raw material, i.e. iron copper and carbon is got out, its proportioning is：Atomized iron powder is 96.8%；Carbon is 0.70%, copper Powder is 2%, then adds the lubricant that content is 0.5%；

2. above-mentioned mixed powder is compressed to density 7.10g/cm under 600MPa pressure³Tooth（Chain）Take turns green compact；

3. sinter, by the tooth（Chain）Wheel part is sintered in 1200 DEG C of temperature, and the time of sintering is 20 minutes, sintering Carried out in vacuum sintering furnace；

4. anneal：Annealing temperature is 850 DEG C；Atmosphere is nitrogen, and annealing soaking time is 60 minutes, from annealing temperature after annealing The cooling velocity spent between 300 DEG C is 0.1 DEG C/S；

5. extrude（Finishing）：Extruded on the press reequiped by single lead screw ex truding briquetting machine or sizing rolling machine, extrusion deformation degree L2 is (da-d)/2 × 8%, and for internal gear, then L2 >=(d-da)/2 × 2%, wherein, da is tip diameter, and d is tooth root Circular diameter, is shown in Fig. 1 and Fig. 2.For external tooth, extrusion die former（Cavity plate）At least it is divided into two parts：Guide section 1 and sizing Section 2, as shown in Figure 6.For internal tooth, plug is at least divided into two parts：Guide section 3 and sizing section 4, as shown in Figure 8；

6. it is heat-treated：Bulk heat treatmet, 850 DEG C of quenching and preserving heat, soaking time 30 minutes, carbon potential is 0.7%, temperature For 200 DEG C, 120 minutes are incubated.

Pattern is shown in Fig. 9 before teeth portion extruding；Pattern is shown in Figure 10 after teeth portion extruding；Pattern is shown in Figure 11 before flank extruding；Flank is squeezed Pattern is shown in Figure 12 after pressure；Pattern is shown in Figure 13 after tooth top extruding；Pattern is shown in Figure 14 after tooth root extruding；Flank of tooth pattern is shown in figure after heat treatment 15；Heat treatment backgear center portion pattern is shown in Figure 16.It can be clearly seen by these photos, the close of teeth portion is significantly improved after extruding Degree.

Embodiment two:

1. the mixed powder of raw material, i.e. siderochrome molybdenum and carbon is got out, its proportioning is：Iron alloy powder（Chromium is 3.0%, and molybdenum is 0.5%, other inevitable materials, less than 1%, iron is surplus）For 50%, straight iron powder is 48.7%；Carbon is 0.8%, is then added Content is 0.5% lubricant；

2. above-mentioned mixed powder is compressed to density 7.2g/cm3 tooth under 600MPa pressure（Chain）Take turns green compact.

3. sinter, by the tooth（Chain）Wheel part is sintered in 1120 DEG C of temperature, and the time of sintering is 20 minutes, sintering Based on nitrogen, the ratio of hydrogen carries out in 10vol% sintering furnace；

4. anneal：Annealing temperature is 850 DEG C；Atmosphere is nitrogen, and annealing soaking time is 60 minutes, from annealing temperature after annealing The cooling velocity spent between 300 DEG C is 0.1 DEG C/S.

5. extrude（Finishing）：Extruded on the press reequiped by single lead screw ex truding briquetting machine or sizing rolling machine, extrusion deformation degree L2 is (da-d)/2 × 10%；

6. it is heat-treated：After high-frequency quenching, case depth 0.5mm, temperature is 200 DEG C, is incubated 130 minutes.

Embodiment three:

1. the mixed powder of raw material, i.e. siderochrome molybdenum and carbon is got out, its proportioning is：Iron alloy powder（Chromium is 17.0%, and molybdenum is 1.0%, other inevitable materials, less than 1%, iron is surplus）For 99.2%；Carbon is 0.3%, and it is 0.5% then to add content Lubricant；

2. by above-mentioned mixed powder, temperature and pressure are density 6.60g/cm under 600MPa pressure³Tooth（Chain）Take turns green compact；

3. sinter, by the tooth（Chain）Wheel part is sintered in 1200 DEG C of temperature, and the time of sintering is 60 minutes, sintering Carried out in vacuum sintering furnace, cooling stage after sintering is annealed for 60 minutes in 890 DEG C of insulations, after annealing from annealing temperature to Cooling velocity between 300 DEG C is 0.15 DEG C/S；

4. extrude（Finishing）：Extruded on the press reequiped by single lead screw ex truding briquetting machine or sizing rolling machine, extrusion deformation degree L2 is (da-d)/2 × 5%；

5. it is heat-treated：Carburizing and quenching, 920 DEG C of carburizing temperature, 120 minutes time, carbon potential is 1.0%, and temperature is 200 DEG C, it is incubated 130 minutes.

Example IV:

1. the mixed powder of raw material, i.e. siderochrome molybdenum and carbon is got out, its proportioning is：Iron alloy powder（Chromium is 3.0%, and molybdenum is 0.5%, other inevitable materials, less than 1%, iron is surplus）For 45%, straight iron powder is 54.3%；Carbon is 0.2%, is then added Content is 0.5% lubricant；

2. by above-mentioned mixed powder, temperature and pressure are density 7.2g/cm under 600MPa pressure³Tooth（Chain）Take turns green compact；

3. sinter, by the tooth（Chain）Wheel part is sintered in 1120 DEG C of temperature, and the time of sintering is 20 minutes, sintering Based on nitrogen, the ratio of hydrogen carries out in 10vol% sintering furnace；

4. extrude（Finishing）：Extruded on the press reequiped by single lead screw ex truding briquetting machine or sizing rolling machine, extrusion deformation degree L2 is (da-d)/2 × 5%；

5. it is heat-treated, carburizing and quenching, quenches 900 DEG C of carburizing temperature, carbon potential is 1.0%, is incubated 120 minutes；Temperature is 200 DEG C, it is incubated 130 minutes.

Embodiment five:

1. the mixed powder of raw material, i.e. iron molybdenum ambrose alloy and carbon is got out, its proportioning is：Iron alloy powder（Molybdenum is 0.5%, and copper is 1.5%；Nickel is 1.75%；Other inevitable materials, less than 1%, iron is surplus）For 98.7%；Carbon is 0.8%,

Then the lubricant that content is 0.5% is added；

2. above-mentioned mixed powder is compressed to density 7.05g/cm3 tooth under 600MPa pressure（Chain）Take turns green compact；

3. sinter, by the tooth（Chain）Wheel part is sintered in 1120 DEG C of temperature, and the time of sintering is 20 minutes, sintering Based on nitrogen, the ratio of hydrogen carries out in 10vol% sintering furnace；

4. anneal：Annealing temperature is 880 DEG C；Atmosphere is nitrogen, and annealing soaking time is 60 minutes, from annealing temperature after annealing The cooling velocity spent between 300 DEG C is 0.2 DEG C/S；

5. extrude（Finishing）：Extruded on the press reequiped by single lead screw ex truding briquetting machine or sizing rolling machine, extrusion deformation degree L2 is (da-d)/2 × 8%；

6. it is heat-treated, after high-frequency quenching, case depth 0.8mm, temperature is 180 DEG C, is incubated 100 minutes.

Flank of tooth pattern is shown in Figure 17 after heat treatment；Heat treatment backgear center portion pattern is shown in Figure 18.

Embodiment six:

1. the mixed powder of raw material, i.e. iron nickel and carbon is got out, its proportioning is：Atomized iron powder is 96.8%；Carbon is 0.70%, nickel Powder is 2%, then adds the lubricant that content is 0.5%；

2. above-mentioned mixed powder is compressed to density 7.10g/cm under 600MPa pressure³Tooth（Chain）Take turns green compact；

3. sinter, by the tooth（Chain）Wheel part is sintered in 1200 DEG C of temperature, and the time of sintering is 20 minutes, sintering Carried out in vacuum sintering furnace；

4. anneal：Annealing temperature is 850 DEG C；Atmosphere is nitrogen, and annealing soaking time is 60 minutes, from annealing temperature after annealing The cooling velocity spent between 300 DEG C is 0.1 DEG C/S；

5. extrude（Finishing）：Extruded on the press reequiped by single lead screw ex truding briquetting machine or sizing rolling machine, extrusion deformation degree L2 is (da-d)/2 × 8%；

6. it is heat-treated：Bulk heat treatmet, 850 DEG C of quenching and preserving heat, soaking time 30 minutes, carbon potential is 0.7%, temperature For 200 DEG C, 120 minutes are incubated.

Embodiment seven：

1. the mixed powder of raw material, i.e. iron molybdenum and carbon is got out, its proportioning is：Ferromolybdenum powder（Molybdenum is 0.85%, can not be kept away Other materials exempted from, less than 1%, iron is surplus）For 98.5%；Carbon is 1.0%, then adds the lubricant that content is 0.5%；

2. above-mentioned mixed powder is compressed to density 7.0g/cm under 600MPa pressure³Tooth（Chain）Take turns green compact.

3. sinter, by the tooth（Chain）Wheel part is sintered in 1120 DEG C of temperature, and the time of sintering is 60 minutes, sintering Carried out in vacuum sintering furnace either based on nitrogen, the ratio of hydrogen is carried out in 10vol% sintering furnace；

4. anneal：Annealing temperature is 850 DEG C；Atmosphere is nitrogen, and annealing soaking time is 60 minutes, from annealing temperature after annealing The cooling velocity spent between 300 DEG C is 0.05 DEG C/S.

5. extrude（Finishing）：Extruded on the press reequiped by single lead screw ex truding briquetting machine or sizing rolling machine, extrusion deformation degree L2 is (da-d)/2 × 8%；

6. it is heat-treated, after high-frequency quenching, case depth 1.0mm, temperature is 200 DEG C, is incubated 130 minutes.

Embodiment eight：

1. the mixed powder of raw material, i.e. iron molybdenum and carbon is got out, its proportioning is：Ferromolybdenum powder（Molybdenum is 1.5%, unavoidably Other materials, less than 1%, iron is surplus）For 99.2%；Carbon is 0.3%, then adds the lubricant that content is 0.5%；

2. above-mentioned mixed powder is compressed to density 7.0g/cm3 tooth under 600MPa pressure（Chain）Take turns green compact.

3. sinter, by the tooth（Chain）Wheel part is sintered in 1120 DEG C of temperature, and the time of sintering is 60 minutes, sintering Carried out in vacuum sintering furnace either based on nitrogen, the ratio of hydrogen is carried out in 10vol% sintering furnace；

4. extrude（Finishing）：Extruded on the press reequiped by single lead screw ex truding briquetting machine or sizing rolling machine, extrusion deformation degree L2 is (da-d)/2 × 8%；

5. it is heat-treated：After carburizing heat treatment, 900 DEG C of carburizing temperature, carburizing soaking time 120 minutes, carbon potential 0.9%, tempering Temperature is 200 DEG C, is incubated 130 minutes.

Embodiment nine:

1. the mixed powder of raw material, i.e. iron nickel and carbon is got out, its proportioning is：Atomized iron powder is 96.8%；Carbon is 0.70%, nickel Powder is 2%, then adds the lubricant that content is 0.5%；

2. above-mentioned mixed powder is compressed to density 7.10g/cm under 600MPa pressure³Tooth（Chain）Take turns green compact；

3. sinter, by the tooth（Chain）Wheel part is sintered in 1200 DEG C of temperature, and the time of sintering is 20 minutes, sintering Carried out in vacuum sintering furnace；It is cooled to 850 DEG C to be annealed, annealing soaking time is 60 minutes, from annealing temperature after annealing Cooling velocity between to 300 DEG C is 0.1 DEG C/S；

4. extrude（Finishing）：Extruded on the press reequiped by single lead screw ex truding briquetting machine or sizing rolling machine, extrusion deformation degree L2 is (da-d)/2 × 8%；

5. it is heat-treated：Bulk heat treatmet, 850 DEG C of quenching and preserving heat, soaking time 30 minutes, carbon potential is 0.7%, temperature For 200 DEG C, 120 minutes are incubated.

Embodiment ten:

1. the mixed powder of raw material, i.e. iron copper and carbon is got out, its proportioning is：Atomized iron powder is 96.8%；Carbon is 0.70%, copper Powder is 2%, then adds the lubricant that content is 0.5%；

2. above-mentioned mixed powder is compressed to density 7.10g/cm3 tooth under 600MPa pressure（Chain）Take turns green compact；

3. sinter, by the tooth（Chain）Wheel part is sintered in 1200 DEG C of temperature, and the time of sintering is 20 minutes, sintering Carried out in vacuum sintering furnace；

4. anneal：Annealing temperature is 850 DEG C；Atmosphere is nitrogen, and annealing soaking time is 60 minutes, from annealing temperature after annealing The cooling velocity spent between 300 DEG C is 0.1 DEG C/S；

5. extrude（Finishing）：Extruded on the press reequiped by single lead screw ex truding briquetting machine or sizing rolling machine, extrusion deformation degree L2 is (da-d)/2 × 8%, and for internal gear, then L2 >=(d-da)/2 × 2%, wherein, da is tip diameter, and d is tooth root Circular diameter, is shown in Fig. 1 and Fig. 2.For external tooth, extrusion die former（Cavity plate）At least it is divided into two parts：Guide section and sizing Section.For internal tooth, plug is at least divided into two parts：Guide section and sizing section.Structural representation is shown in Fig. 6, shown in 8；

6. it is heat-treated：High-frequency quenching and tempering.

Claims (7)

1. the preparation method of a kind of powder metallurgical gear, sprocket wheel, it is characterised in that comprise the following steps：

1) raw material is got out, carbon, iron, chromium, molybdenum, copper, nickel are mixed into mixed powder by following mass percent, matched as carbon：0.1 ~1.5%, copper：0~4%, nickel：0~5%, molybdenum：0~2%, chromium：0~18%, the inevitable impurity no more than 2%, Iron：Surplus；

Wherein, chromium, molybdenum, copper, nickel are added with ferroalloy or foundry alloy form, and carbon is added with form of graphite, then add quality hundred Point than content be 0.1~1% lubricant；

2) above-mentioned mixed powder is more than on 400MPa press in pressure and is pressed into density for 6.6~7.4g/cm³Gear or chain Take turns green compact；

3) said gear or sprocket wheel green compact are sintered in 1000 DEG C~1350 DEG C of temperature, the time of sintering is 5~180 points Clock；

4) annealed in non-oxidizing atmosphere or do not select annealing, annealing temperature is 750~1080 DEG C, during annealing insulation Between 5~200 minutes, for carbon content less than 0.3% and molybdenum, chromium, nickel and copper alloy total content be less than 2% gear or chain Wheel；

5) extrude：Extruded on the press reequiped by single lead screw ex truding briquetting machine or sizing rolling machine, amount of compression L2 be more than outside circle and The 2% of the difference of root diameter, i.e. L2 >=(da-d)/2 × 2%, for internal gear, then amount of compression L2 is more than root circle and tooth top The 2% of the difference of circular diameter, then L2 >=(d-da)/2 × 2%, wherein, da is tip diameter, and d is root diameter；

6) it is heat-treated：Hardening heat is 750~1250 DEG C, is incubated 10~240 minutes, and temperature is 150~600 DEG C, insulation 5 ~200 minutes, it is more than 0.4% gear for carbon content after sintering or sprocket wheel is heat-treated using high frequency or intermediate frequency, heat treatment 0.2~5mm of case depth, temperature is 150~600 DEG C, is incubated 5~200 minutes, or is returned using high frequency or Medium frequency induction Fire；

The step 5) extruding is uniform extruding or non-homogeneous extruding, when using non-homogeneous extruding, amount of compression L2 is maximum Deflection, in extrusion process, for external tooth, extrusion die former is at least divided into two parts of guide section and sizing section, right For internal tooth, plug is at least divided into two parts of guide section and sizing section.

2. preparation method according to claim 1, it is characterised in that：The step 1) lubricant and graphite using bonding Processing mode is added.

3. preparation method according to claim 1, it is characterised in that：The step 2) suppress using warm-pressing formation or mould Thermoforming, the pressing pressure of press is 600Mpa.

4. preparation method according to claim 1, it is characterised in that：The step 3) sintering be to enter in vacuum sintering furnace Carried out based on row either nitrogen, in the sintering furnace that the ratio of hydrogen is 1~75vol%.

5. preparation method according to claim 1, it is characterised in that：The step 4) after annealing, from annealing temperature to 300 Cooling velocity between DEG C is less than 1.5 DEG C/S.

6. preparation method according to claim 1, it is characterised in that：The step 3), step 4) sintering and annealing two Procedure unites two into one, and is incubated temperature control in annealing temperature after sintering terminates, time and cooling according to annealing It is required that dropping to room temperature.

7. preparation method according to claim 1, it is characterised in that：The step 6) heat treatment terminate after, also increase spray Ball processing.