The surface that meets the specified technical requirements is machined on a certain part of the cnc workpiece. Before machining, the cnc workpiece must occupy a correct position on the machine tool relative to the tool. This process is often referred to as the "positioning" of cnc workpieces. After the cnc workpiece is positioned, due to the cutting force, gravity, etc. in the machining, a certain mechanism should be used to "clamp" the workpiece so that the determined position remains unchanged. The entire process of "positioning" to "clamping" of workpieces is collectively referred to as "installation."
How to place cnc workpieces
The installation of cnc workpieces is an important issue in mold processing. It not only directly affects the machining accuracy, the speed of workpiece installation, stability, but also the productivity. In order to ensure the relative positional accuracy between the machined surface and its design basis, the cnc workpiece should be installed so that the design reference of the machined surface occupies a correct position relative to the machine tool. When the workpiece is installed, its design reference must coincide with the axis of the machine spindle.
There are a variety of different mounting methods when machining parts on a variety of different machine tools. The mounting method can be summarized into three types: direct alignment method, line alignment method, and fixture mounting method.
(1) Direct alignment method
When this method is used, the correct position that the cnc workpiece should occupy on the machine tool is obtained through a series of attempts. The specific method is to directly mount the cnc workpiece on the machine tool, and use the stylus on the dial gauge or the stylus to correct the correct position of the workpiece by visual inspection, and check the side until it meets the requirements.
The accuracy of the direct positioning method and the speed of the alignment are determined by the accuracy of the alignment, the alignment method, the alignment tool, and the skill level of the worker. Its shortcomings are that it takes a lot of time, has low productivity, and has to be operated by experience. It has high requirements on workers' technology, so it is only used in single-piece and small-batch production. In addition, when the positioning accuracy of the workpiece is required to be high, for example, when the error is less than 0.01-0.05 mm, it is difficult to meet the requirements by the fixture (because of manufacturing errors), the precision measuring tool has to be used, and the technical level is high. Workers use direct alignment to locate the accuracy requirements.
(2) scribing method
This method is a method of aligning a workpiece on a machine tool with a scriber to draw a correct line on the blank or semi-finished product. Obviously, this method requires one more scribing process. The drawn line itself has a certain width, and there is a scribe error in the scribe line. There is also an observation error when correcting the position of the cnc workpiece. Therefore, the method is mostly used for small batch production, low blank precision, and large cnc machining parts. It is not suitable to use the roughing of the fixture.
(3) Using the fixture installation method
The fixture is an additional device of the machine tool. It is pre-adjusted on the machine tool relative to the position of the tool before the cnc workpiece is installed. Therefore, it is not necessary to find the positioning one by one when processing a batch of cnc workpieces. The technical requirements, which are both labor-saving and trouble-saving, are efficient positioning methods and are widely used in batch and mass production.
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