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A kind of preparation method of powder metallurgy cam

A powder metallurgy and cam technology is applied in the field of preparation of iron-based powder metallurgy cams, which can solve the problems of time-consuming and labor-intensive, decreased material weldability, unreasonable utilization of materials, etc., achieves simple and reasonable process, solves connection problems, and ensures reliability. Effect

Active Publication Date: 2019-03-12
NBTM NEW MATERIALS GRP
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

(1) It is difficult for traditional camshafts to meet the above requirements at the same time, and the use of materials is not reasonable
(2) It is difficult to manufacture a compact structure with densely arranged cams in the traditional integral casting or forging production mode
(3) The traditional method of manufacturing camshafts requires a large number of machining processes and consumes a lot of machining hours. It is difficult to make new breakthroughs in terms of machine tools, tools, fixtures, operators and working areas.
(4) The traditional processing needs to strengthen the wear resistance of the cam surface, such as chilling, quenching or remelting of the cast camshaft, carburizing and quenching of the surface of the forged camshaft, etc., which are carried out on the whole camshaft and accompanied by deformation , most of them are aligned manually, which is time-consuming and labor-intensive and difficult to ensure accuracy
(5) The mechanical processing of the cam profile is difficult, which is also an important factor affecting the processing quality
However, as the carbon content increases, the weldability of the material decreases, especially for laser welding
It is very difficult to laser weld a cam with a carbon content higher than 0.8% to a camshaft

Method used

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  • A kind of preparation method of powder metallurgy cam
  • A kind of preparation method of powder metallurgy cam
  • A kind of preparation method of powder metallurgy cam

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0044] 1) Prepare the ingredients

[0045] Cam outer ring A: the mixed powder of iron, chromium, molybdenum and carbon, and its ratio is: iron alloy (3.0% of chromium, 0.5% of molybdenum, less than 1% of unavoidable other substances, and iron as the balance) is 98.8%; 0.70% carbon, then add lubricant with a content of 0.5%;

[0046] Cam inner ring B: 99.4% iron powder; 0.10% carbon, and then add 0.5% lubricant;

[0047] 2) Form the above mixed powder

[0048] Cam outer ring A: pressure 500MPa, green density 6.95g / cm 3 ;

[0049] Cam inner ring B: pressure 600MPa, green density 7.15g / cm 3 ;

[0050] 3) Put part B of the inner cam ring into the inner hole of the outer cam ring A, and assemble it into the green cam body shown in Figure 1, and place the assembled green body on the sintering setter;

[0051] 4) Sintering, the cam part is sintered at a temperature of 1250° C., the sintering time is 20 minutes, and the sintering is carried out in a vacuum sintering furnace;

...

Embodiment 2

[0054] 1) Prepare the ingredients

[0055] Cam outer ring A: the mixed powder of iron, chromium, molybdenum and carbon, and its ratio is: iron alloy (3.0% of chromium, 0.5% of molybdenum, less than 1% of unavoidable other substances, iron as the balance) is 98.6%; 0.90% carbon, then add lubricant with a content of 0.5%;

[0056] Cam inner ring B: 97.3% iron powder; 0.20% carbon; 2% copper, and then add 0.5% lubricant;

[0057] 2) Form the above mixed powder

[0058] Cam outer ring A: pressure 500MPa, green density 7.00g / cm 3 ;

[0059] Cam inner ring B: pressure 650MPa, green density 7.15g / cm 3 ;

[0060] 3) Put part B of the inner cam ring into the inner hole of the outer cam ring A, and assemble it into the green cam body shown in Figure 1, and place the assembled green body on the sintering setter;

[0061] 4) Sintering, the cam part is sintered at a temperature of 1200° C., the sintering time is 20 minutes, and the sintering is carried out in a vacuum sintering furna...

Embodiment 3

[0064] 1) Prepare the ingredients

[0065] Cam outer ring A: mixed powder of iron, chromium, molybdenum and carbon, the proportion of which is: iron alloy powder (17.0% of chromium, 1.0% of molybdenum, less than 1% of unavoidable other substances, iron as the balance) is 98.5%; 1.0% carbon, then add lubricant with a content of 0.5%;

[0066] Cam inner ring B: iron alloy powder (1.0% molybdenum, less than 1% unavoidable other substances, iron as the balance) 97.3%; carbon 0.20%; copper 2%, and then add lubricant with a content of 0.5%;

[0067] 2) Form the above mixed powder

[0068] Cam outer ring A: pressure 600MPa, green density 6.50g / cm 3 ;

[0069] Cam inner ring B: pressure 650MPa, green density 7.15g / cm 3 ;

[0070] 3) Put part B of the inner cam ring into the inner hole of the outer cam ring A, and assemble it into the green cam body shown in Figure 1, and place the assembled green body on the sintering setter;

[0071] 4) sintering, the cam part is sintered at a ...

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Abstract

Provided is a preparation method of a powder metallurgy cam. The method comprises following steps: dividing a green cam body into inner and outer parts, wherein the outer ring of the cam utilizes high-carbon sintered steel and the inner ring of the cam utilizes low-carbon sintered steel, respectively pressing mixed powder on a pressing machine to produce the green body for the outer ring of the cam with the density of 6.25-7.4g / cm<3> and the green body for the inner ring of the cam with the density of 6.5-7.4g / cm<3>; loading the inner ring of the cam into an inner hole of the outer ring of the cam; sintering; carrying out heat treatment; and mechanically processing and polishing the cam which is subjected to sintering and heat treatment with the predetermined dimension according to the technical requirement. Compared with the prior art, the preparation method of the powder metallurgy cam has following advantages: heat treatment material for the cam is composed of two parts; the outer ring of the cam has high strength and resistant to wear; the inner ring of the cam has good welding performance, thereby ensuring welding and laser welding in particular; the connection problem between the cam and a cam shaft is effectively solved; the inner and outer rings are closely combined so that metallurgical bonding level is reached; and reliability of parts is ensured.

Description

technical field [0001] The invention belongs to the field of powder metallurgy, in particular to a method for preparing an iron-based powder metallurgy cam. Background technique [0002] The camshaft is an important part of the engine valve train, which is responsible for the timing opening and closing of the intake and exhaust valves of each cylinder of the engine. The camshaft realizes the switch of the valve by the intake and exhaust valves of the cylinder jacked by the cam. [0003] The sides of the cam are peach-shaped. The purpose of its design is to ensure sufficient intake and exhaust of the cylinder, specifically to complete the opening and closing of the valve in the shortest possible time. In addition, considering the durability of the engine and the smoothness of operation, the valve cannot produce too much impact due to the acceleration and deceleration process in the switching action, otherwise it will cause serious wear of the valve, increased noise or other...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): B22F5/08B22F3/16
Inventor 包崇玺詹学救周国燕赵万军
Owner NBTM NEW MATERIALS GRP