In precision machining, both the equipment and the choice of processing scheme are very important. In batch production, in order to improve the qualified rate and production efficiency, we can use special fixture. It can not only improve the precision of parts, but also reduce labor intensity and increase economic benefit. Therefore, special fixture is an important process equipment in precision machining. The production of intake cam bracket parts is as high as 960000 pieces per year, which has reached the condition of mass production. In order to improve the production efficiency and economic benefit of the precision machining in batch production, a special fixture was designed for the NC center of the machining part.
In the NC machining of parts, two holes and one side positioning are adopted, and the corresponding positioning components on the fixture are two pins. To avoid interference in the installation of the workpiece due to overpositioning, one of the two pins should use a diamond pin. In the process of fixture design, it is necessary to consider whether the workpiece is located, avoid underpositioning or over-positioning, ensure precision machining accuracy, shorten clamping time, improve labor productivity, expand the process range of machine tool, realize one machine with multiple functions and operate conveniently. Reduce labor intensity, reduce the technical requirements of workers and other fixture design requirements. The design includes positioning device, clamping device, knife guide element and so on. The fixture design needs to adopt one side and two pin positioning, one pin is designed to be circular, the other pin is designed to be diamond, and the two pins have also designed elastic positioning pin, which can not only eliminate the error of blank hole, but also ensure the reliability of positioning.
Jigs and fixtures are divided into two categories according to the general usage, one is general fixture, such as flat clamp, dividing head, etc. Its advantages are strong adaptability, the disadvantage is that it can only fit the regular workpiece, most of them are manual clamping, low efficiency, etc. Suitable for the production of regular single-piece small-batch precision machining parts. The other is the fixture that is specially designed and manufactured for a part or process, because they are special, called special fixture, which is suitable for medium and small batch production or mass production.