CN1442505A

CN1442505A - Swinging arm hot treatment technology of general small gasoline engine

Info

Publication number: CN1442505A
Application number: CN 03117588
Authority: CN
Inventors: 张权芳
Original assignee: Individual
Current assignee: Individual
Priority date: 2003-03-31
Filing date: 2003-03-31
Publication date: 2003-09-17
Anticipated expiration: 2023-03-31
Also published as: CN1197988C

Abstract

A heat treating technology for the universal rockerarm of small gasoline engine (diameter less than 100 mm) includes such steps as shaping rockerarm by punching, carburizing, quenching, high-temp tempering, preheating and nitriding. It can prevent the brittle fracture of rockerarm.

Description

The rocking arm thermal treatment process of general small gasoline engine

Technical field:

The invention belongs to the rocking arm thermal treatment process of small gasoline engine, particularly diameter of cylinder is the rocking arm thermal treatment process of Φ 100mm with interior general small gasoline engine.

Background technology:

At present, the thermal treatment process of this rocking arm employing comprises that with starting material be 08 steel plate impact briquetting, carburizing, quenching, low-temperaturetempering, polishing.This thermal treatment process is very tight to the technical requirements of cementing furnace, all need adopt atmosphere controlled heat treatment furnace or the cementing furnace of carbon potential in the microcomputer control stove is arranged, simultaneously; the case depth of rocking arm requires extremely strict; its case depth is 0.3～0.5mm; when cementation zone meets the requirements of in limited time, then make rocking arm wear drawing the place of stretching to cause to ooze (generally rocking arm starting material thickness is 1.5～2mm, through draw stretch moulding after with attenuate 0.5mm).It is very big to locate fragility after the quenching, in use ruptures herein, does not reach requirement as cementation zone, and rocking arm wears no resistance, and causes early failure, once above-mentioned defective occurs, has only whole stove to scrap.By statistics, its product percent of pass is 90%.

Summary of the invention:

The objective of the invention is to overcome above-mentioned the deficiencies in the prior art, a kind of rocking arm thermal treatment process of general small gasoline engine is provided, this technology can prevent the rocking arm brittle rupture, reduces the requirement to carburizing equipment, and product percent of pass reaches 100%.

In order to realize the foregoing invention purpose, technical scheme of the present invention comprises plate stamping is shaped to rocking arm, carburizing, quenching, high tempering, shot-peening, nitriding treatment.Its technology is that rocking arm is placed in the common gases cementing furnace, after being heated to 880～920 ℃, splash into kerosene, making the interior carbon potential of stove is 0.8～1.1, furnace pressure is 15～25mm water column, be incubated 80～200 minutes, making its case depth is 0.4～0.9mm, directly coming out of the stove quenches cools off in 3～8% the aqueous sodium hydroxide solution, subsequently rocking arm is put into 580～650 ℃ tempering stove tempering, be incubated 30～60 minutes, make rocking arm surface hardness HRC20～30, after rocking arm is cleaned, put into preheating oven and be preheating to 300～350 ℃, being incubated 5～10 minutes, is 32～38% with rocking arm with putting into the cyanogen radical content, and temperature is the interior processing of 540～570 ℃ nitrogenize salt bath 120～150 minutes, the water-cooled of coming out of the stove, cleaning eliminates residual salt, make rocking arm surface ε phase nitride layer degree of depth 0.008-0.020mm, hardness HV450-600, total nitrogenize layer depth 0.2～0.4mm.The used nitridation salt of the present invention is commercially available nitridation salt., this salt is the QPQ nitridation salt that Chengdu Tool Research Institute produces.

This technology compared with prior art has following technique effect:

1. prevent the rocking arm brittle rupture.Rocking arm after handling with the present invention, through destructive test, rocking arm is clenched 45 ° and do not rupture.Cause is by the rocking arm after this art breading, and what its heart portion obtained is the good sorbite tissue of comprehensive mechanical performance, sees Figure of description 6; Its hardness gradient changes greatly, illustrates that the rocking arm top layer is hard, and its heart portion is soft, and no fragility is seen Figure of description 4.And with the rocking arm after the existing art breading major cause of failure takes place easily is that its textura epidermoidea is a martensite, sees Figure of description 7; When case depth reaches 0.5mm, when the carburizing of stretching attenuate place, ooze and wear, after the quenching, its heart portion will be a martensitic stucture also, see Figure of description 7, and the hardness gradient figure after the existing art breading illustrates that the top layer of rocking arm and heart portion change little, very big fragility is arranged, see Figure of description 3.As everyone knows, martensitic stucture is that a kind of fragility is organized greatly, thereby easily brittle rupture takes place in use.With the rocking arm of this art breading, carry out bench testing in 200 hours by JB/T5135.1-2001 " general small-size gasoline engine test stand performance test method " and JB/T5135.2-2001 " general small-size gasoline engine reliability, endurance test and assessment method ".Test-results meets JB/5135.1-2001 and JB/T5135.2-2001 standard fully.

2, reduction is to the requirement of carburizing equipment

Because the tolerance zone of rocking arm case depth expands 0.4-0.9mm to, to carbon potential, temperature uniformity in the stopping property of common cementing furnace, the stove, soaking time etc. are all less demanding, saved the investment to carburizing equipment.And the tolerance zone of existing rocking arm case depth is 0.3-0.5mm, and tolerance zone is little, and to carbon potential, temperature uniformity in the stopping property of cementing furnace, the stove, it is very tight that soaking time etc. all require, is difficult to operation, easily causes to put in order the processed rocking arm of stove and scrap.

3, product percent of pass reaches 100%

With the rocking arm of this art breading petrol motor, the top layer after its nitrogenize is a ε phase nitride layer, has high wear resistance, sees Figure of description 5.As long as control nitriding temperature and nitridation time, guarantee the tissue and the degree of depth of nitride layer, just can guarantee that the qualification rate of rocking arm after processed reaches 100%.More prior is to guarantee that rocking arm in use has 100% security and reliability.

Description of drawings:

Fig. 1 is the thermal treatment process schema of existing rocking arm,

Fig. 2 is a thermal treatment process schema of the present invention,

Fig. 3 is the hardness gradient figure of existing technology after to rocking arm thermal treatment,

Fig. 4 is the hardness gradient figure of this technology after to rocking arm thermal treatment,

Fig. 5 invents the nitrided surface layer metallographic structure figure after the rocking arm thermal treatment,

Fig. 6 invents the metallographic structure figure of heart portion after the rocking arm thermal treatment,

Fig. 7 is the top layer metallographic structure figure of existing technology after to rocking arm thermal treatment.

Embodiment:

Behind the rocking arm high tempering, put into polishing machine polishing 5-10 minute.

Tempering temperature in the rocking arm thermal treatment process of 168F petrol motor is 620 ± 10 ℃, be incubated 30 ± 10 minutes, make rocking arm surface hardness HRC25 ± 3, after cleaning, place to be preheating to 330 ± 10 ℃ in the preheating oven, be incubated 10 minutes, putting into the cyanogen radical content again is 35%～379%, and temperature is the interior processing of 560 ± 5 ℃ nitrogenize salt bath 130 ± 10 minutes, makes rocking arm surface ε phase nitride layer degree of depth 0.011mm, hardness is HV460-500, and total nitrogenize layer depth is 0.25-0.35mm.

The rocking arm thermal treatment process of 182F petrol motor is with the rocking arm thermal treatment process of 168F petrol motor.

Claims

1. the rocking arm thermal treatment process of a general small gasoline engine is characterized in that this technology may further comprise the steps:

(1) impact briquetting of rocking arm;

(2) rocking arm is placed in the common cementing furnace, be heated to 880～920 ℃, splash into kerosene, making the interior carbon potential of stove is 0.8-1.1, furnace pressure is the 15-25mm water column, be incubated 80～200 minutes, making its case depth is 0.4～0.9mm, directly comes out of the stove, quench and cool off in 3%～8% the aqueous sodium hydroxide solution, the tempering stove of rocking arm being put into 580～650 ℃ carries out tempering subsequently, is incubated 30～60 minutes, makes rocking arm surface hardness HRC20～30;

(3) with after the rocking arm cleaning, place to be preheating to 300-350 ℃ in the preheating oven, be incubated 5-10 minute;

(4) rocking arm being put into the cyanogen radical content is 32%～38%, temperature is the interior processing of 540～570 ℃ nitrogenize salt bath 120～150 minutes, the water-cooled of coming out of the stove, cleaning eliminates residual salt, make rocking arm surface ε phase nitride layer degree of depth 0.008-0.020mm, hardness is HV450-600, and total nitrogenize layer depth is 0.2-0.4mm.

2. the rocking arm thermal treatment process of general small gasoline engine according to claim 1 is characterized in that behind the rocking arm high tempering, puts into polishing machine polishing 5-10 minute.

3. the rocking arm thermal treatment process of general small gasoline engine according to claim 1, it is characterized in that the tempering temperature in the rocking arm thermal treatment process of 168F petrol motor is 620 ± 10 ℃, be incubated 30 ± 10 minutes, make rocking arm surface hardness HRC25 ± 3, after cleaning, place and be preheating to 330 ± 10 ℃ in the preheating oven, be incubated 10 minutes, putting into the cyanogen radical content again is 35%～37%, temperature is the interior processing of 560 ± 5 ℃ nitrogenize salt bath 130 ± 10 minutes, make rocking arm surface ε phase nitride layer degree of depth 0.011mm, hardness is HV460-500, and total nitrogenize layer depth is 0.25-0.35mm.