The requirements and selection principles of the fixture for CNC milling machine
In order to produce high-precision parts, it is necessary to use a special fixture for the machining of CNC milling machines. The fixture plays an important role in ensuring the machinability of the workpiece and is known as the third hand of the CNC milling machine.
In order to ensure the machinability of the workpiece and the accuracy of the machining, the fixture of the CNC milling machine should meet the following requirements:
1. The strength of the fixture should be appropriate, and its design should be reasonable. It should be able to withstand the machining force of the machining material and ensure sufficient rigidity.
2. The groove of the fixture should be symmetrical and smooth, and free of burr and deformation.
3. The accuracy of the surface contact between the fixture and the workpiece should meet the requirements.
4. The clamping accuracy, force and rigidity of the fixture should meet the requirements.
5. The fixture should be easy to disassemble and assemble.
6. All contact surfaces of the fixture should be covered with protective layers to avoid damage to the machined surface of the workpiece.
The most commonly used fixtures for CNC milling machines are: fixed fixtures, position forming fixtures, multi-position fixtures and adjustable fixtures.
1. Fixed fixture: It is generally made into a combination of clamping components and connecting components. According to the shape of the workpiece, the workpiece is fixed in the fixture by the clamping components. The connected components are connected with the machine by screws or pins, so that the workpiece can be fixed relative to the table.
2. Position forming fixture: It is generally composed of a set of positioning components, connective components and screw components. According to the shape of the workpiece, the combination of the positioning components is used to position the workpiece and the connecting components are used to fix the assembly to the table.
3. Multi-position fixture: According to the shape of the workpiece, a number of necessary components are combined to form a fixture for the machining of the CNC milling machine.
4. Adjustable fixture: It is a type of fixture with certain adjustability, which is suitable for processing workpieces of different sizes.
In addition to the above-mentioned four kinds of commonly used fixtures for CNC milling machines, there are other small kinds of fixtures, such as: horizontal four-sided fixtures, claw fixtures, guide jaw fixtures, sink fixtures, etc.
The choice of the fixture of the CNC milling machine should consider convenience of use, rigidity, accuracy and cost. In general, the following selection principles can be followed.
(1) Select an appropriate fixture according to the size, shape and machining accuracy of the workpiece.
(2) The chosen fixture should be easy to adjust, adjust and disassemble.
(3) The fixture should have sufficient rigidity, stability and repeatability.
(4) The clamping force of the fixture should be adjustable and the force should be uniform.
(5) The surface contact between the fixture and the workpiece should be smooth and non-slip.
(6) The clamping components of the fixture should be reliable.
(7) The cost of the fixture should be reasonable.
The correct choice of the fixture will directly affect the machining accuracy and efficiency of the CNC milling machine. By following the above selection principles, it is possible to choose the best fixture for the machining of the CNC milling machine.
