First, meet the process requirements.
The geometry and machining area of the workpiece determine the type and size of the machine. Generally speaking, CNC lathes are selected for the processing of revolving bodies.
Generally, CNC lathes and vertical machining centers should be selected for the machining accuracy requirements of some rotary planes or grooves, and turning centers should be selected for products with high accuracy requirements, especially for products with high position requirements.
When drilling and tapping in a working face (the small aperture is less than 12mm), it is advisable to use the arm-clamping drilling tapping machine, and the large aperture is suitable for the vertical machining center.
Suitable for small and medium-sized workpieces with machining requirements such as plane milling, free-form surface milling, drilling and boring. In a plane or several different positions with low requirements, vertical machining centers are selected, while parts with relatively small workpiece sizes such as nonferrous metals, soft metals, ferrous metals (iron, steel, stainless steel, etc.). ) is suitable to be completed in the form of a vertical machining center with a fourth axis.
It is more reasonable to choose a horizontal machining center for large-scale multi-faceted workpieces with high precision (the outline is more than 500mm square).
The complex surface machining, plane machining, drilling and tapping of large parts are generally completed by the gantry machining center, and the gantry side milling head can be used for side machining requirements.
The number of processes and processing time determine the selection and type of tool magazine.
The process is simple, the workpiece does not need to be changed frequently (the processing time of a tool is more than 10 minute), and the labor intensity of workers is moderate. You can choose a machining center (CNC vertical milling machine, CNC horizontal milling machine) without a tool magazine.
If the working procedure is complex and the demand for tools is large, machining centers with automatic tool changing devices are generally selected. When the tool processing time is long (more than 10 minute), the influence of tool changing time (7-30 seconds in cap type) can be ignored, and the cap type machining center can be selected; In order to improve the machining efficiency and take up the obvious tool changing time, the manipulator tool library (also called disc and knife arm type) is selected, which is characterized by the manipulator grasping the target tool and the tool on the spindle at the same time, and has the function of preselecting the tool. The cutter head with the selected target cutter number can be processed in parallel while rotating, and the tool changing time is between 2.5 and 5 seconds.
Second, meet the accuracy requirements.
According to our experience, 0.05mm is the watershed between roughing machine tools and finishing machine tools, and it is also necessary to consider that the accuracy of new machine tools will decrease after the running-in period. Therefore, the accuracy required by the drawing (mainly the position tolerance, and the shape tolerance such as ovality can be reduced by 0.005-0.0 15 mm through the selection of technology and cutting tools, such as milling by circular arc and boring with a boring tool).
At present, the popular practice is that the products with general accuracy requirements (> =0. 1mm) can basically meet the requirements of numerical control equipment (Ningbo Evergrande mechanical products can be selected); For products with precision requirements (0.05-0. 1 mm), domestic equipment should be selected, and the quality of key parts should be Taiwan Province Province or above. For products with precision requirements (0.0 1-0.05mm), domestic machines with design capability, Taiwan Province machines with factories in Chinese mainland or original machines in Taiwan Province province should be selected. Precision requirements (in some cases, for products with high precision requirements and large quantities, it is recommended to buy domestic machines with good system stability for rough machining and semi-finish machining, and then finish machining with a small number of high-end equipment, so that both efficiency and investment cost are greatly reduced, which is a good choice.
3. Chip efficiency and process optimization determine processing efficiency.
Firstly, the heavy cutting of mechanical structure, the inverted Y-shaped design of widening the bottom of the vertical machining center column, the widening of the front and rear direction of the column and the reasonable arrangement of reinforcing ribs are the keys to improve the rigidity and stability of the machine tool; Second, the size of the motor in the electrical system determines the processing capacity of the machine tool. For mold processors, it is suitable to consider heavy cutting machine tools; However, in product processing, especially for products with small machining allowance in large quantities, it is necessary to optimize the process, tighten or concentrate the working procedures, reduce the auxiliary working hours such as clamping and handling, and improve the efficiency of machine tools, including the selection of quick tool changing devices.
Fourth, the purchase cost plus the use cost determines the value of the machine tool.
In the case of inquiry comparison, after the supplier is finally determined, the purchase cost is determined by the purchase contract price. Generally speaking, it is easier than the price, and it is also something that people must do when purchasing. It is worth mentioning that the configuration determines the "maintenance and stability of accuracy", but if a good configuration cannot be guaranteed, it is two different things, just as people often say that "German parts are assembled in China, and what comes out is far from the original ones in Germany". Here is a concept of use cost, which includes the failure rate of machine tools, the timeliness and accuracy of maintenance, the labor intensity and energy consumption of workers, such as tools, electricity, the size of occupied space, the level requirements of operators and so on. ...
To sum up, when choosing a machine tool, we should not only choose the machine tool body that can meet the processing requirements, but also consider the technical strength of suppliers that affect the use cost, so as to minimize the relatively invisible use cost.