Boring machine processing
The machined base is fixed to the workbench using the machined foot plane as a reference plane. Single and small batches can be processed on a universal trampoline. Find the position of the positive axis on the work surface according to the line on the base. Press the foot with a bolt and pull out the inner circle and the stop.
Mass production is processed on a dedicated combination bed. The axis is automatically aligned using the two foot holes that are hinged on the base and the pins on the positioning base. Positioning the bottom plate automatically finds the axis with the machine. The base foot and the positioning platen are pressed against the table by bolt pressing plates or pneumatic clamps, and then cut. Since the two ends of the stop and the inner circle are machined in one setup, the coaxiality is guaranteed by the accuracy of the machine tool and is less affected by the error generated in the positioning. Therefore, this processing method is relatively stable and reliable. During processing, the pressing force acts on the foot, and the influence of the deformation of the frame is also small due to the pressing force.
Common non-conformance analysis
After machining, the deformation of the seat stop, the inner circle, and the deviation of their coaxiality are quality problems that often occur in production, and the causes are basically attributed to the following factors.
● Improper clamping, excessive clamping force, unsatisfactory contact surface of the chassis, and looseness of the chassis stopper are the main reasons for deformation and coaxiality deviation of the chassis. Therefore, it must be operated in accordance with the process specifications. The proper relaxation of the clamping force before finishing can not be ignored.
● Due to the internal stress of the casting or weldment. The magnitude of the internal stress is related to the structural shape of the frame, the material, and the method of manufacturing the blank. The welding frame, the cast steel stand and the high-strength cast iron stand shall be annealed to eliminate internal stress. After casting the ordinary gray cast iron machine base, it is necessary to place the appropriate time for the so-called "natural aging" treatment to eliminate the internal stress. Then process. However, for workpieces with strict deformation restrictions, it is necessary to perform internal stress relief annealing after roughing to perform finishing.
●The cast iron material is unqualified. If there is too much free graphite contained in iron, the strength and rigidity of the frame are reduced, and deformation is likely to occur.
●The rigidity of the base is poor. If the design is not considered during the clamping process, the stress on the frame is much larger than that in normal operation. The designed frame is too weak and prone to deformation. For this reason, it is necessary to appropriately increase the wall thickness or to add reinforcing ribs, or to use a material having higher strength and better rigidity.
● Due to the error of the machine itself and the influence of the measured temperature. To this end, the machine tool should be repaired regularly, and measures to eliminate the influence of temperature measurement should be taken.
