| Automobile engine is the key component in the car, it is the important part of automobile power system, its performance has a direct impact on the overall performance of the car. While the engine gear is one of the key parts of the engine, it will be the components together, and passes the timing relationship, ensure the camshaft, crankshaft, an air pressure pump, oil pump, fan and other components according to the design of the mutual relations between work. Our company is in heavy vehicle transmission and engine gear professional manufacturers, from 92 to start producing engine gear, has now become Dongfeng, bavin company, Futian company and CUMMINS in global production plant's main supplier. In recent years, with the rising prices of raw materials and customer cost reduction requirement, improve the engine gear technology economy and the process ability to guarantee company has become a pressing matter of the moment. On the basis of the existing equipment, how to improve process capability to reduce product loss reduction rate, become our technology personnel must study the issue. Process capability is a process product quality rather than quantity of ability, this ability is reflected in the processing process is controlled and stable degree. Process stability refers to the process of quality characteristics of volatility is simply the result of a normal fluctuation caused by, rather than special fluctuation factors. Process ability is composed of process capability index Cp to measure.Process capability index is the measurement of a process to meet the requirements of the degree. Customer requirements embodied in the characteristics of the product specification, is what we usually say that the product of a particular characteristic tolerance T. It said the customer requirements are strict or loose, process capability index defined as: Cp = customer requirements / process capability. The process is stable, quality characteristic obeys normal distribution N(μ,σ2), the standard deviation in the size of that process stable degree,σis smaller, more stable process. Stable process, product quality and distribution in theμ±3σinterval, interval width is 6σ, width of an interval is smaller, more stable process, process capability is stronger, so the process capability is defined as the 6σ. So Cp = T / 6σ, usually at the request of the customer is not easy to change, improve the Cp pathway is to reduce theσ. The processing system of 5MIE people, machine, material, method, measurement, the ring has a direct impact on the size of. Our current approach is in production field data collection product processing, according to the data of production of x--barR control chart, in order to determine whether the process is controlled and stable state, if the process is controlled, then the calculation of Cp value, meet the requirements of closed. Does not meet the requirements, according to the experience of process improvement. The advantage of this is: direct and simple, to save time. Its shortcoming is: only by experience on process improvement is one-sided, for complex processing system is very difficult to accurately identify the improvement point, sometimes need repeated measurement, test cost is high, the process capability will be high and sometimes low, no good continuity. This approach is not fundamentally solve the problem of improving process capability the method, can only be used as a short-term observation process reference value, not as a process of improving capacity method. Six Sigma technique provides a complete set of scientific methods to solve the problem, so it is widely used to process improvement of.Simply put, six sigma is the removal of process variation and defects; removal of variation and defect opportunity; removal of no value factors and activity. Simply stated, six sigma is the company's vision; is a kind of management system; is to solve the problem of the scientific method; to the product, process and enterprise innovation and design as the goal, to obtain, assessment and application of customers, competitors and their own wisdom as a means of a set of highly structured strategy for looks; with customers, major innovation, continuous improvement, collective participation tools; setting challenging goals. Enterprises in any work can be seen as a process, all processes are for the production needs of users of products and services. The process is generally flawed, so the process is the opportunity exists. Defects and rework caused by decreased ability to process; process deviates from the target value will cause loss of quality inspection is not reliable; 100%.In engine machining, gear inner hole accuracy directly affects the accuracy of involute gear inner hole, because parts of the test datum but also parts installation datum. In this paper the engine gear inner hole process capability as the Six Sigma technology research and application of the object, in our company is the first, through research and application, to find the effects of inner hole process capability factors and improvement. For the next six sigma technique in our company and other parts of the process improvement of the research and application of example.In the study by using Six Sigma technique in the flowchart, causal matrix, measurement system analysis, potential failure mode and effects analysis, capacity analysis, graphics technology, correlation analysis, experimental design, an element and multiple regression, analysis of variance and other tools. |
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