Hot Precision Forging Technology of Straight Bevel Gears
The bevel gear transmission for precision parts processing is a gear transmission used to transmit motion and power between two intersecting shafts in space. Its gear teeth are distributed on a truncated cone, and the tooth profile gradually becomes smaller from the large end to the small end. For the convenience of calculation and measurement, the big-endian parameter is usually taken as the standard value. The angle Σ between the two axes of a pair of bevel gears is called the shaft angle. The value can be selected arbitrarily according to the transmission needs. In general machinery, Σ=90° is often used. Straight bevel gear transmission is shown in Figure 1.
The precision forging process of spur bevel gears for precision parts processing has been used in the mass production of planetary bevel gears and half-axle bevel gears for automobile and tractor differentials, as well as the manufacturing process of bevel gears in transmission boxes of agricultural machinery and construction machinery. The precision of the tooth profile after precision forging is 8 grades, which can be used directly without machining. The comparison of the two production processes of planetary bevel gear cutting and precision forging is shown in the table below.
The hot precision forging process of spur bevel gears has been used for many years. The main process in the early stage is to use a friction press for open die forging. In order to ensure the tooth profile performance
Enough to be completely filled, generally requires pre-forging, final forging and subsequent two cutting flashes to complete. A large number of hot forging forming and warm forging finishing are used for one-fire two forging
The process and technological process are: blanking → heating → upsetting → pre-forging → cutting flash → cleaning → final forging → cutting flash → air cooling, inspection → human storage. The equipment configuration for precision parts processing is generally:
(1) Billet making: high-speed band saw, sandblasting machine.
(2) Heating 4000Hz, 160kW intermediate frequency induction heating furnace.
(3) 800kN open press for upsetting.
(4) Pre-forging 3000kN friction press.
(5) Cutting flash 1600kN open press.
(6) 3000kN friction press for final forging.
(7) 1600kN open press with secondary cutting flash.
(8) Stack cold storage bin.
In recent years, in order to save human resources and improve production efficiency, precision parts processing has developed automated precision forging gear technology and equipment on hot die forging presses in China. The main process flow: blanking → heating → upsetting → pre forging → final forging →Cutting flash→air cooling, inspection→man storage. A hot die forging press is used for multi-station die forging and edge trimming. The stepping beam is used for transmission between procedures, and it is equipped with an intermediate frequency induction heating device, which can realize the unmanned production process.