1. CNC Machine Tool Combination Fixture
The combined fixture is developed on the basis of the highly standardized and standardized series of fixture components. From a pre-fabricated set of various shapes and specifications. The standard components with interchangeability and wear resistance are assembled with composite parts. These components can be assembled into various types of fixtures such as turning, milling, planing, drilling and boring according to different process requirements. The fixture can be disassembled and returned after use. Class preservation, so that it can be assembled into another form of fixture again, so it is recycled until the component reaches the wear limit and is scrapped. Normally, the component can be used for 10-15 years. The combination fixture is flexible and changeable, easy to master and use, and can adapt to a variety of small batches, Market demand components with fast changes and short cycles can be used repeatedly; fast assembly, the average design and assembly time is 5% to 20% of the design and manufacturing time required for special fixtures, and the use of combined fixtures is much more economical than special fixtures. It can be said that the combined fixture is a flexible fixture.
Combination fixtures are divided into two series: groove system and hole system. Groove fixture means that the components of the combination fixture are mainly positioned and clamped by grooves. Hole fixtures refer to components that are mainly positioned and clamped by holes. Features It is convenient for translation adjustment. It is widely used in ordinary machine tools for machining parts with general precision. The feature of hole-based fixtures is that they are easy to rotate and adjust. The rigidity and accuracy are higher than those of slot-based fixtures. With the continuous development of hole-based fixture component design Improvement, the new generation of components not only maintains its own advantages, but also partially adopts the groove structure, which is more widely used.
2. The special needs of CNC machine tools and the advantages of hole system fixtures
With the continuous improvement of the NC rate of machine tools in various enterprises, CNC machine tools show many special requirements that are different from ordinary machine tools: rough machining requires the clamp to have high rigidity and can withstand high power, and fast cutting and finishing require the workpiece to be produced in the fixture. Positioning and clamping errors are minimized to improve work efficiency. It is required that the combined fixture components can be integrated into one large, medium and small, and are installed on the same base plate, so as to adapt to the simultaneous processing of single or multiple pieces, etc.
The operation procedure of the slot system fixture is more complicated, and it is also inseparable from the time-consuming measurement and adjustment. The rigidity and accuracy are not as good as that of the hole system fixture.
The position of the workpiece in the machine tool coordinates can be determined by measuring and adjusting, which saves time. When using a multi-fixture base plate, it can assemble a single large part fixture and multiple small and medium parts fixtures, with high work efficiency and good flexibility. Clamps have many advantages. Therefore, it is especially suitable for supporting tooling or accompanying fixture for CNC machine tools and flexible manufacturing systems, and occupies a dominant position. The application coverage is also far more than that of slot fixtures. It can be said that the higher the numerical control rate of machine tools, the wider the application of hole fixtures.
In the late 1980s, my country began to research and develop the design and management of combined fixture components. According to the characteristics of modern machining, a new generation of hole system fixture component system was developed. This system exerts the translation adjustability of the groove and the rotation adjustability of the hole. Advantages, can be directly assembled to obtain any linear size and height size, which can ideally meet the requirements of difficult, high rigidity and high-precision fixtures.