Since CNC machining centers are far more expensive than ordinary machine tools, they are subject to more constraints, and the choice of machine tools is more important. Proper selection is the key to making good use of the machining center and making the machining center work. When purchasing a machining center, it is especially important to carefully examine these five key points:
First, the rigidity of the machining center
Since the rigidity of the machining center directly affects the production efficiency and the machining accuracy of the machine tool, the machining speed of the machining center is much higher than that of the ordinary machine tool, and the motor power is also higher than that of the ordinary machine tool of the same specification, so the rigidity of the structural design is much higher than that of the ordinary machine tool. . When ordering, the process requirements, allowable torque, power, axial force and maximum feed force can be checked according to the values provided by the manufacturer. In order to obtain the high rigidity of the machine tool, it is often not limited to the size of the part, but a machine tool having a size of one to two sizes relative to the part size is selected.
Second, the machining center processing accuracy
Processing accuracy directly affects the quality of your products. Many people will directly influence the buyer’s decision when negating the accuracy of your machine. It is important to note that machining accuracy and machine accuracy are two different concepts. It is wrong to regard the positional accuracy on the manufacturer’s sample or on the product certificate as the machining accuracy of the machine tool. The positional accuracy indicated on the sample or certificate is the accuracy of the machine itself, and the machining accuracy is the sum of the errors produced by various factors of the entire process system, including the tolerances allowed by the machine itself. When selecting the type, the evaluation method of the process capability kp can be referred to as the basis for selecting the accuracy. In general, the calculation should be greater than 1.33.
Third, the selection of CNC system in machining center
The numerical control system is the core brain of the machining center operation, and the numerical control function is divided into basic functions and selection functions. The basic functions are inevitable, and the selection function is only available to the manufacturer when the user selects these functions. The function of the numerical control system must be selected according to the performance requirements of the machine tool. When ordering, it is necessary to complete the required functions, not to miss, and avoid the waste caused by low usage rate, and also pay attention to the correlation between the functions. In the choice of CNC system, the performance varies greatly. Should be selected according to needs, can not unilaterally pursue high indicators, so as not to cause waste. When selecting multiple machine tools, use the CNC system of the same manufacturer as much as possible, so that operation, programming and maintenance are more convenient.
Fourth, the number of axes and the number of linked axes
The number of axes and the number of linked axes should meet the requirements of typical workpiece machining. The number of axes is also a sign of the machine grade. Under normal circumstances, with the same manufacturer, the same specifications, the same precision of the machine tool, adding a standard coordinate axis, the cost is increased by about 35%. Although increasing the number of axes can enhance the function of the machine tool, it is necessary to pay attention to the process requirements and capital balance.
Five, automatic tool changer and tool magazine capacity
The choice of automatic tool changer mainly considers tool change time and reliability. Short tool change time can improve productivity, but the tool change time is short. The general tool changer has a complicated structure, high failure rate and high cost. Over-emphasis on the tool change time will greatly increase the cost and increase the failure rate. According to statistics, about 50% of the faults in the machining center are related to the automatic tool changer. Therefore, under the premise of meeting the requirements of use, the high-reliability automatic tool changer should be selected to reduce the failure rate and the whole machine cost.
The working quality and tool magazine capacity of the automatic tool change will directly affect the performance and quality of the machining center. The magazine capacity is based on the principle that a complex machined part requires the tool.