1. Selected by NC Machining object
Before deciding on the object, you must first explicitly prepare the object for processing. Generally speaking, the parts with the following characteristics are suitable for machining centers:
The multi-process intensive workpiece refers to a lot of cutting tools to be machined on one workpiece.
Positioning cumbersome workpiece such as a certain hole spacing precision requirements of the porous processing, the use of machine tool positioning accuracy high characteristics, it is convenient to implement.
Repetitive production of workpiece is suitable for processing single-piece small batch production. Small quantities refer to 1-100 pieces, each batch number is not many, but need to repeat production. In addition, even if the workpiece shape size is different, but also similar workpiece, easy to achieve a group processing (GT) process parts.
Complex shape parts die, aviation parts and other complex workpiece, can use automatic programming technology in machining centers on various special-shaped parts.
Cabinet type, plate parts in the horizontal machining center using rotary table, the box parts for multi-faceted machining, such as spindle box, pump body, valve body, cylinder body, and so on. If even the top of the clamping in one of the processing, you can choose the five-body machining center. Vertical machining Center is suitable for machining box cover cylinder head, planar cam and so on. Gantry Machining Center is used for machining large cabinet and plate parts such as diesel locomotive cylinder, machining center pillar, bed body, printing wall plate machine, etc.
2. The selection of NC machine tool specifications
According to the size of the machining workpiece determined, the working table size and three linear coordinate system of the required machine tools are determined accordingly. Worktable size should ensure that the workpiece can be successfully loaded on top of the workpiece, machining dimensions must be in each coordinate itinerary, in addition to consider the change of space and the coordinates of the limitations of interference areas.
3. Selection of precision of NC machining tool
The precision classification of machining centers is common and precise, and its main precision projects see table below: Machining Center main precision Project Precision (mm) precision (mm) linear positioning accuracy ± 0.01/± 0.005/Total repeat positioning accuracy ± 0.006 ± 0.002 Milling Circle Precision 0.03-0.04 0.015
According to the machining accuracy of the workpiece, the user selects the corresponding precision grade machine tool, the batch production part, the actual machining precision numerical value may be the positioning accuracy 1.5-twice times. The common type of machine tool batch processing 8 precision workpiece, precision machine tool processing can reach 5-6 level, but must have the constant temperature and so on craft condition, so precise machine tool uses strict, the price is high.
4. Selection of knife Library capacity
Machining centers manufacturers to the same specifications of the machine, usually set up 2-3 different capacity of the knife library, such as horizontal machining center knife storage capacity of 30, 60, 80, vertical machining centers have 16, 24, 32 capacity of the knife library. When the user is selected, depending on the process analysis result of the workpiece to determine the required quantity, it is usually necessary to determine the capacity of the cutter base in a single part of the clamping tool, because the cutter is required to reschedule the tool, otherwise the cutter management is complex and error prone.
From the statistical data to look at the vertical machining center selection of 20 knife base, horizontal machining center selection of 40 knife of the knife storehouse appropriate. Of course, the actual need to be finalized. For flexible manufacturing unit (FMC) or flexible manufacturing system (FMS) machining Center machine tool, its knife library capacity should be selected large capacity knife library, even the configuration of interchangeable knife library.
5. Selection of the function and accessory of machine tool
Selected machining Center machine tool, in addition to basic functions and basic components, but also provide users according to their own requirements of the selection of features and accessories, said select features, select attachments (optional attachment). With the development of CNC technology, more and more content to choose, the composition of the price in the host of the proportion of more and more large, so the unclear purpose of a large selection of attachments is not economical, the so-called "prepared" ordering the guiding ideology is essentially wasted. Therefore, the selection should be analysed comprehensively and the long-term factors should be considered appropriately.
Select function mainly for CNC system, the price increase is not much, but the use of a lot of convenient features, should be properly configured to complete a bit, and can be more than the common attachment of machine tools, you can consider a machine multi-purpose, but must consider the interface is common.
6. Calculation of machining beats and number of machine tools
According to the selected workpiece, then analysis the route, in this route to select the process in the processing center to prepare for the processing of the time to calculate the time beat.
According to the current process parameters, the cutting time of each operation is estimated, and the auxiliary time usually takes 10%-20% of the cutting time.