The design of tooling fixtures is generally carried out according to the specific requirements of a certain process after the machining process of the parts is formulated. When formulating the process, the possibility of fixture implementation should be fully considered. When designing the tooling fixture, you can also propose modifications to the process if necessary. The design quality of tooling fixtures should be measured by whether it can stably guarantee the processing quality of the workpiece, high production efficiency, low cost, convenient chip removal, safe operation, labor saving and easy manufacturing and maintenance.
In many actual production processes, general-purpose fixtures cannot meet production requirements, resulting in low production efficiency and low processing quality. However, the design of special-purpose fixtures is difficult and it is impossible to design a complete set of fixtures. Here is a brief introduction to the key points of milling machine fixture design.
Milling machine fixtures must have sufficient clamping force to prevent the workpiece from loosening in the fixture. This is because the milling process is not continuous cutting, and the machining allowance is generally large, so the cutting force is large, and the magnitude and direction of the cutting force may change at any time, causing vibration in the cutting process.
Milling machine fixtures should have sufficient stiffness. The processed surface of the workpiece should try not to exceed the clamp body or the outside of the workbench. On the premise of ensuring that the clamp has sufficient chip removal space, the height of the clamp should be reduced as much as possible (it is recommended that the height-to-width ratio not exceed 1~1.25).
Fully consider the condition of the workpiece blank. For fixtures positioned on the blank surface of castings and forgings, the blank drawing should be used as the basis for designing the fixture, so as not to affect the reliability and rationality of positioning due to blank margin size and shape errors.
Consider adding auxiliary supports when appropriate. In order to reduce the blank error and possible deformation during milling, auxiliary supports should be added appropriately in weak areas to enhance the overall rigidity of the fixture.
Milling machine fixtures should have a self-locking function to prevent the workpiece from loosening due to vibration during processing.
Necessary tool setting devices should be considered. Correctly select the tool setting device to adjust and determine the relative position of the fixture and milling cutter. The tool setting device should be set in a position that is convenient for use with the feeler gauge and easy to observe, and should be placed at the end of the milling cutter that begins to cut into the workpiece.
There should be enough space for chip removal. The milling process will produce a large amount of chips, so sufficient chip removal and chip holding space must be arranged to ensure smooth discharge. In addition, according to the processing needs, the pouring and discharge of cutting fluid should be considered.