What are the specific components of the machine tool fixture
[China Machine Tool Business Network Technology News] "A workman must first sharpen his tools if he is to do his work well." Tools are a symbol of the progress of human civilization. Since the end of the 20th century, both modern manufacturing technology and mechanical manufacturing process automation have achieved substantial development. However, with the continuous innovation of tools (including fixtures, cutting tools, measuring tools, auxiliary tools, etc.), their functions remain extremely significant. Machine tool fixtures have a direct impact on the processing quality, productivity and production cost of parts. Therefore, fixtures are important process equipment in both traditional manufacturing and modern manufacturing systems.
1. Functions of Machine Tool Fixtures
(1) Guarantee processing accuracy. When clamping workpieces with a machine tool fixture, the relative positional relationship between the workpiece, the cutting tool and the machine tool can be accurately determined, which can guarantee processing accuracy.
(2) Improve production efficiency. Machine tool fixtures can quickly position and clamp workpieces, which can reduce auxiliary time and improve pro
duction efficiency.
(3) Reduce labor intensity. Machine tool fixtures adopt mechanical, pneumatic and hydraulic clamping devices, which can reduce workers' labor intensity.
(4) Expand the processing range of machine tools. The use of machine tool fixtures can expand the processing range of machine tools. For example, using a boring jig on a lathe or drilling machine can replace a boring machine for boring, making lathes and drilling machines have the functions of a boring machine.
2. Classification of Machine Tool Fixtures
2.1 Classification by application scope of fixtures
(1) General fixtures. General fixtures refer to fixtures whose structures have been standardized and have a large application range. For example, three-jaw chucks and four-jaw chucks for lathes, flat-nose pliers and dividing heads for milling machines, etc.
(2) Special purpose machine tool fixtures. Special purpose machine tool fixtures are fixtures specially designed and manufactured for a certain process of a specific workpiece. They are suitable for applications with relatively stable products and large output.
(3) Modular fixtures. Modular fixtures are assembled from a set of pre-manufactured standard components and assembled units. They feature flexible and changeable structures, short design and assembly cycles, and fixture parts and components can be reused for a long time. They are suitable for applications such as multi-variety single-piece small-batch production or new product trial production.
(4) Group fixtures. Group fixtures are fixtures designed and manufactured for each part group when group processing is adopted. When switching to process another part within the same group, processing can be carried out only by adjusting or replacing individual components on the fixture. Group fixtures are suitable for application in multi-variety, small and medium-batch production.
(5) Trunnion (carry along) fixtures. It is a mobile fixture used on automatic production lines. Before a workpiece enters the automatic line for processing, the workpiece is first loaded into the fixture, then the fixture together with the processed workpiece sequentially moves from one workstation to the next along the automatic line, and the workpiece is only unloaded from the fixture when the workpiece finishes processing and exits the automatic line. It is a fixture that always moves along the automatic line together with the workpiece.
2.2 Classification by type of machine tool used
Different types of machine tools have different fixture structures. Accordingly, fixtures can be divided into types such as lathe fixtures, drilling machine fixtures, milling machine fixtures, boring machine fixtures, grinding machine fixtures and modular machine tool fixtures.
2.3 Classification by power source of the fixture
According to the clamping power source used by the fixture, fixtures can be divided into manual clamping fixtures, pneumatic clamping fixtures, hydraulic clamping fixtures, pneumatic-hydraulic linkage clamping fixtures, electromagnetic fixtures, vacuum fixtures, etc.
3. Composition of Special Purpose Machine Tool Fixtures
A fixture is generally composed of the following components or devices:
(1) Positioning elements. Positioning elements are components used to determine the correct position of the workpiece. The positioning surface of the processed workpiece is in direct contact or fits with the positioning element of the fixture.
(2) Clamping device. The clamping device is a device that enables the workpiece to maintain its correct positioning position under the action of external force.
(3) Tool setting elements and guiding elements. Tool setting elements and guiding elements refer to components in the fixture used to determine (or guide) the correct positional relationship of the cutting tool relative to the fixture positioning elements, such as drill bushes, boring bushes, tool setting blocks, etc.
(4) Connecting elements. Fixture connecting elements refer to components used to determine the correct position of the fixture on the machine tool and connect the fixture to the machine tool, such as positioning keys installed on the bottom surface of a milling machine fixture, etc.
(5) Other elements and devices. According to processing requirements, some fixtures also need to be equipped with devices such as indexing and rotating devices, cam profiling devices, workpiece lifting devices and auxiliary supports.
(6) Fixture body. The fixture body is the base component used to connect all fixture elements and related devices into a whole, and the fixture is connected to the machine tool through the fixture body.
Positioning elements, clamping devices and the fixture body are the basic components of a fixture, and other components can be configured as required.