Development of Large Powder Metallurgy Gear Set

Our company has recently received instructions on development projects. The development project is quite special. It is a gear set of large machinery. This large powder metallurgy gear set is far larger than the powder metallurgy parts commonly used in automobiles, which greatly tests the overall equipment capacity of powder metallurgy manufacturers. Because the products are relatively large, the pressure conversion method used is to select the press used according to the cross section of the manufacturing products. The press used for forming must be above 600T, The shaping press must be above 630T to meet the manufacturing requirements.

Expand the scope of reading Application of Powder Metallurgy Gears

Powder metallurgy gear is a high-tech product with less processing and less weapon processing. It is difficult to count the whole powder metallurgy parts separately, but according to the weight and the number of parts, the proportion of automobile, motorcycle and watch is much larger than that of powder metallurgy parts in other fields. Therefore, from the increase of the proportion of automobiles, motorcycles and watches in the whole P/M parts, P/M gears have developed rapidly in the whole P/M parts. According to the characteristics of parts, gears belong to structural parts, and the weight of structural parts in the whole iron base parts is much larger than other parts. It is a powder metallurgy part.

Powder metallurgy gear is a kind of powder metallurgy part widely used in various automobile engines. Through one-time forming and finishing process, it does not need other post-treatment processes, and can completely meet the requirements of dimensional accuracy, especially the tooth profile accuracy. Therefore, compared with the traditional machining method, the material input and manufacturing are greatly reduced, which is a typical product reflecting the characteristics of powder metallurgy. Powder metallurgy parts take the category part name 3360 automobile engine as an example. Camshaft, crankshaft timing pulley, pump, pump pulley, driving and driven gears, driving and driven sprockets, cams, bearing covers, swing arms, bushings, thrust plates, valve tubes, inlets, exhaust valve seats Various low-speed synchronizer hubs and components of automobile transmissions, clutch gear bases

Development prospect

After nearly ten years of rapid development, the powder metallurgy industry still has the following gap with similar foreign industries.

(1) With many enterprises and small scale, the economic benefits are quite different from those of foreign enterprises.

(2) The products are crossed, and the enterprises reduce the price each other, resulting in fierce competition.

(3) Most enterprises lack technical support, backward R&D capability and low product grade, so it is difficult to compete with foreign countries.

(4) The shortage and distress of reinvestment.

(5) Technological equipment and military facilities are backward.

(6) Product exports are few and trade channels are not smooth. After China's accession to the WTO, these shortcomings and weaknesses will be improved. Because after joining WTO, the market internationalization will further expand the powder metallurgy market. At the same time, with the entry of foreign funds and technologies, the level of powder metallurgy and related technologies will also be improved and developed.

Expand the scope of reading New Powder Forging Technology and Its Influence on Gears

1. High speed compression of powder forged gear

Sweden has developed a high-speed pressing project. The development of this process can develop large powder forged parts with high density of more than 5kg, compress the powder to within 20ms, and press repeatedly within 300ms, which can also further improve the density. High speed pressing can break through the limit of powder forging by mass production. The traditional press needs higher forming pressure, which is limited by the tonnage of the press, and high-speed pressing is not limited. The powder density based on prealloying and diffusion alloying can reach 7.4~7.7 g/cm3. This new manufacturing technology * * * has recently been introduced into the powder forging industry. 2. Gear forming and work hardening

Forming work hardening is to combine the powder forging forming process with the quenching heat treatment process to improve the material performance, so as to reduce the cost. The forming work hardening process can eliminate the heat treatment process after forming, ensure the high strength and hardness performance, and reduce the production cost. In addition, quenching will increase the residual internal stress and deform the part, which makes it difficult to control the dimensional tolerance of the part. The forming work hardening process can reduce deformation because the cooling rate after forming is far lower than the quenching cooling rate. Therefore, the die work hardening process is suitable for large complex parts that are difficult to handle.

3. High temperature forming

High temperature forming is an important measure to improve strength. Through high-temperature forming, some oxides are recovered, atomic diffusivity is improved, composition uniformity is improved, holes and gaps are fully opened and expanded, which is suitable for new powder forging materials such as high-speed steel, stainless steel and superalloy. This improves the density, mechanical properties, axial/rotational bending fatigue strength, corrosion resistance, and physical properties of the part.

However, there are also shortcomings such as increased equipment loss, increased energy consumption, increased furnace maintenance costs, reduced productivity, increased part deformation, reduced part coaxiality, reduced cooling rate and other process problems. Therefore, the high temperature forming of powder forged parts will increase some additional costs.