The gearbox has input shafts, output shafts, reverse shafts and gears. The main function of the gearbox housing is to
support the drive shafts, to ensure the center distance and parallelism between the shafts, and to ensure the correct
installation of the gearbox housing parts and other components connected to them, so the processing quality directly
affects the total transmission Assembly accuracy and motion accuracy, but also affect the car's working accuracy and
service life, so the gearbox housing requires high quality.
Material type of gearbox housing
In the early stage of the gearbox housing, mainly gray cast iron, the molding was easy, the shock absorption was good,
and the cost was low. As the user's requirements for driving comfort of the car are increased and the lightweight technology
is mature, the gearbox housing portion of the car is replaced by die-cast aluminum. At present, the gearbox housing is
mainly made of gray cast iron and die-cast aluminum.
Difficulties in processing the gearbox housing
(1) There are many processing contents, and it is necessary to change machine tools and tools frequently;
(2) The processing precision is high, the processing quality of ordinary machine tools is difficult to guarantee, and the process
flow is long, the number of turnovers is many, and the production efficiency is difficult to improve;
(3) The shape is complicated, and most of them are thin-walled shells, and the workpiece has poor rigidity, which is difficult to clamp.
Processing tool for gearbox housing
The following factors should be considered when selecting a tool:
1. Machine tools: imported domestically, years of use, overall rigidity, spindle diameter and maximum speed, spindle runout,
machine tool power,
2, the workpiece: the workpiece material is cast iron, die-cast aluminum, aluminum alloy silicon (Si) composition, processing
parts are end face, inner hole, shape tolerance requirements, surface roughness Ra, Rz, holes are through holes, blind holes ,
stepped holes, dimensional tolerances,
3, fixture: hydraulic and pneumatic, whether the installation is reliable,
4, cutting fluid: brand, type, concentration, coolant pressure,
At present, the gearbox housing is mainly for mass production of parts. When the gray cast iron and die-cast aluminum gearbox
housings are mass-produced by conventional carbide tools, the high-speed cutting will produce very fast wear, resulting in
shortened blade life, so Halnn recommends CBN inserts for machining gray cast iron gearbox housings to extend tool life and
increase productivity and product quality.
Application of Halnn CBN inserts in gray cast iron gearbox housing
Milling plane process: Multi-axis gantry milling machine is used to mill the plane to ensure the positional accuracy between the
planes and improve the production efficiency. The CBNinserts BN-S300 CBN grade inserts can be milled at a cutting speed of
2000m/min, which is nearly 5 times higher than the limit cutting speedof the hard alloy. The finished surface finish is guaranteed
to be within Ra1.6. Boring process: The boring process is the key to theproduction of the gearbox housing. It is necessary to
ensure the positional accuracy and machining accuracy requirements. In themass production process, a combination machine
tool or machining center is used for production. The use of CBN inserts BNK30 CBN grade inserts boring can extend tool life
and increase productivity.
