Gearbox shell machining process designManufacturing Engineering and TechnologyMachiningMechanical Industry Press In March 2004, version 1 p560564（Serope kalpakjian） （Steven R.Schmid）AbstractGearbox shell is a more complex structure of spare parts box, its high precision, complex process, and the processing quality will affect the overall performance engine, so it has become the engine manufacturers focus parts one.Machining process planning must guarantee the machining quality of parts, to meet the technical requirements stipulated in drawings, at the same time should also have high productivity and efficiency. Therefore, machining process planning design is an important work, requires designers must have a rich experience in production practice and wide range of mechanical manufacturing technology basic theory knowledge. In the specified procedure, should according to the production of parts and the existing equipment conditions, taking the processing quality into account, productivity and economy requirements, after repeated analysis and comparison, to determine the optimal or the best solution.1.Technical Characteristics of the gearbox shellThe gearbox shell process features are: the structure of complex shape; processing plane, more than holes; uneven wall thickness and stiffness is low; processing of high precision typical of box-type processing part. The main processing of the surface of cylinder block top surface, the main bearing side, cylinder bore, the main and camshaft bearing bore holes and so on, they will directly affect the machining accuracy of the engine assembly precision and performance, mainly rely on precision equipment, industrial fixtures reliability and processing technology to ensure the reasonableness.2.The gearbox shell process design principles and the basis Design Technology program should be to ensure product quality at the same time, give full consideration to the production cycle, cost and environmental protection; based on the enterprises ability to actively adopt advanced process technology and equipment, and constantly enhance their level of technology. Gearbox shell machining process design should follow the following basic principles:2.1 The selection of processing equipmentThe principle of selection adopted the principle of selection adopted the principle of combining rigid-flexible, processing each horizontal machining center is located mainly small operations with vertical machining center, the key process a crank hole, cylinder hole, balancer shaft hole High-speed processing of high-precision horizontal machining center, an upper and lower non-critical processes before and after the four-dimensional high-efficiency rough milling and have a certain adjustment range of special machine processing;2.2 Concentration process principleFocus on a key process in principle process the body cylinder bore, crankshaft hole, Balance Shaft hole surface finishing and the combination of precision milling cylinder head, using a process focused on a setup program to complete all processing elements in order to ensure product accuracy The key quality processes to meet the cylinder capacity and the relevant technical requirements;3.The gearbox shell machining process design the main contentGearbox shell complex structure, high precision, arge size, is thin-walled parts, there are a number of high precision plane and holes. Engine block machining process characteristics; mainly flat and the hole processing, processing of flat generally use planing, milling methods such as processing, processing of hole used mainly boring, processing and multi-purpose drilling holes. As the cylinder complex structure. so how to ensure that the mutual position of the surface processing precision is an important issue.3.1 The selection of blankGearbox shell on the materials used are generally gray cast iron HT150,HT200,HT250,there is also cast aluminum or steel plate, this engine block using high-strength alloy cast iron. Cylinder in the processing prior to aging treatment in order to eliminate stress and improve the rough casting mechanical properties.Improve the rough accuracy, reduction of machining allowance, is to improve the automated production line system productivity and processing quality of the important measures. As the foreign box-type parts of rough quality and high precision, and its production-line system has been implemented directly on the blank line, not only eliminating the need for blank check device also saves the rough quality problems due to waste of machining time, increase overall efficiency. Therefore, the refinement of rough is to improve the productivity of the most promising way out. For the engine block production line, can be rough in parts on-line pre-milling six face, removing most of the margin, to facilitate direct on-line parts.3.2 Machining process selection and processing of the benchmarkChoose the right processing technology