The base plane of the motor is an important reference for the connection between the motor and the supporting equipment, directly affecting the connection accuracy and the smoothness of operation. Generally, there are two different process routes for machining the base plane: pre-marking as a positioning basis, suitable for single production or large-scale machine base machining; and using a special fixture for positioning, which is used for batch production of series motors. Ms. Can will share some basic machining knowledge with you today.
Two machining schemes for the base foot surface
In one machine base machining scheme, when machining the base plane, the machined end stop and end face are used for positioning, and the machine base is pressed onto the positioning fixture using screws and U-shaped clamps (or pressure plates). By calibrating the height position of the tool along the centerline of the positioning stop, the distance and parallelism between the machine base plane and the machine base centerline after machining can be guaranteed. When machining long or heavy machine bases, auxiliary support points must be installed to reduce vibration during machining.
In another machining scheme for the machine base, the first step is to machine the base plane. Before machining the base plane, the casting surfaces of the inner circle and the stop are not accurate enough or are rough. It is necessary to use an appropriate clamping method to ensure that the wall thickness of the inner circle and the stop to be machined after the base plane is machined is approximately uniform. The specific method is as follows: First, use a tapered sleeve to roughly align the axis of the machine base, then use screw jacks to adjust the end face and the bottom, and finally use large nuts, screws and three-point pressure plates to fix the machine base.
When machining the base plane on a gantry planer or gantry milling machine, in order to improve productivity, several machine bases are usually clamped on the worktable at the same time.
Commonly used base plane machining methods
● Planing. When machining the base plane on a shaper, the fixtures and cutting tools used are relatively simple. The unmachined bottom plane of the machine base serves as a rough reference datum. The machine base is aligned using a level, and it must be clamped securely to prevent loosening due to machining stress or vibration. To ensure the dimensional accuracy of the machine base's center height, the base plane is machined in two processes: rough planing and fine planing. This machining method has low productivity and is rarely used in large-batch production. For medium and large machine bases, machining the base plane on a gantry planer is still relatively common.
● Milling. Milling the base plane of a machine tool is the most common machining method on horizontal milling machines, vertical milling machines, gantry milling machines, and milling power heads. The machining process is shown in the figure. Internal positioning can be achieved using a positioning mandrel or a stop chuck 5, and the symmetry of the two bases is manually aligned. During milling, a large-diameter insert-type cutter head is used, with the cutting edges of each cutter not on the same arc or at the same height. This allows roughing and finishing to be performed simultaneously, approaching continuous cutting with minimal vibration, thus increasing the cutting depth. The maximum cutting depth is as follows: 5-6 mm for cast iron and 3-4 mm for cast steel. Usually, only one pass is needed to machine the base plane. Production efficiency is several times higher than planing, and the machining quality is also better.
For large batches, using a dedicated milling machine to machine the base plane results in higher productivity. Some factories use a four-station dedicated iron milling machine to mill the base plane, which can process four workpieces simultaneously.
● Boring. Large machine bases are also frequently machined on horizontal universal tube presses to create the base plane. Two tools are mounted on the tube head, with the cutting edges of each tool not on the same arc or at the same height. The machining process is still intermittent cutting. Slight vibration occurs when the cutting depth is large. This machining method has high productivity and good quality. Sometimes, the base plane of medium-sized machine bases is also bored.
●Specialized machine tools. A typical and commonly used example is the base milling machine, which uses a pre-machined base stop and end face for clamping and positioning, and completes the milling of the base feet and drilling of the base feet holes in one operation.
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