Design Contents and Improvement Analysis of Tooling Fixture for CNC Milling Machine

During the machining process of CNC milling machines, fixtures play an irreplaceable role. They can ensure that the machine tools, tools, workpieces and other devices are maintained in the correct position, thereby reducing the material costs required for processing, improving the efficiency of production work and reducing Product defect rate. At present, CNC milling machines are moving towards the trend of high-efficiency, precision, intelligence and compounding, which undoubtedly puts forward higher requirements for the design of fixtures. Therefore, it is of great significance to analyze the design content and improvement of CNC machine tool fixtures.

1 Design content of CNC milling tooling fixture

1.1 CNC Milling Fixture Fixing Method

In the method of fixing the fixture of the CNC milling machine, in order to prevent the movement of each workpiece during actual processing, the fixing direction of the workpiece must be consistent with the direction of the acting force, which is also called the fixing manner of the clamping member. When using the fixture to clamp the workpiece, the workpieces held at different times should be kept in a completely consistent position so that the parameters of each workpiece will remain within the proper tolerance after the completion of processing. The clamping of the workpiece takes advantage of the mechanical principles of mechanics, which can produce very large clamping forces in a specific environment with a relatively small force. In general, the clamping member should not be designed to rely solely on one element in the design, but multiple elements should be combined. In the processing of components, the work needs to be removed or installed in advance. In order to enable fixtures to be fixed quickly, the clamping mechanism located inside the fixture needs to be designed with a variety of parts with a higher degree of standardization.

1.2 Design Process of CNC Milling Tooling Fixtures

In the design process of the CNC milling machine tooling fixture, the first step is to perform an all-round analysis of the machining fixture parts, so as to have a general understanding of the characteristics of the various parts inside the fixture fixture in terms of the structure and characteristics of the material. . In addition to fixture materials, the accuracy of the parts and heat treatment technology are key design techniques for CNC milling fixtures. During the machining process of fixtures, it is necessary to clarify the processing standards and before and after processes of each part. The technical parameters of the CNC milling machine will be the basic data needed for the process design of the fixture, and the final determined parameters will also be determined. Tooling tooling at work. Whether to use a clamping method and the molding time of a fixture will have a direct impact on the installation frequency of the workpiece, thus affecting the operation time of the CNC milling machine.

1.3 Tool setting design of CNC milling tooling fixture

When designing fixtures, you should refer to the fixtures and parts of the fixtures to design the tool at the specific position of the milling machine table. Select the appropriate tool type according to the actual length and characteristics of the tool, and then place the tool on the appropriate position of the milling machine table. This is to avoid the collision of the CNC milling machine during the machining process. In addition, the knife design also needs to pay attention to the actual cutting amount of the CNC milling machine, which needs to be determined according to the degree of processing. If rough machining is used, the cutting amount should be increased appropriately, so as to increase the production efficiency; if fine machining is used, then the precision of the knife setting should be considered in the design.

2 Improved Design of CNC Milling Tooling Fixtures

2.1 Design method of clamping multiple workpieces at a time

The power of the CNC milling machine is mainly generated by means of compressed air, and the worker can perform manual tool change while the machining center can complete the automatic tool change. In the process of machining, the machining of the surface can be accomplished by sequentially changing the tool, but this method takes a long time, and the machining center can easily fail when the tool is changed. Therefore, we can save processing time by reducing the number of tool changes, thus ensuring that the CNC milling machine can work in a stable state. For example, a technician can use a design method of clamping multiple workpieces at a time to make certain adjustments to the technical process of fixtures and to minimize the number of tool changer tooling times. In combination with the dimensions of the workpiece and the stroke of the machine tool, we can design a fixture that can hold 8 workpieces at the same time, that is, multi-piece fixture fixtures. When this type of fixture is used to process 8 workpieces, only 4 tool changes are required, which greatly shortens the auxiliary time of the CNC milling machine, thereby enhancing the work efficiency of the CNC milling machine.

2.2 Design Points for Multi-piece Fixture Fixtures

The design points of multiple fixture fixtures mainly include the following aspects:

(1) Reasonably arrange the workpiece. In the design, the workpiece should be reasonably arranged in combination with the workpiece shape, workpiece size, production batch, machine tool stroke, machine tool size and other factors. A proper distance should be maintained between the various workpieces, which will facilitate work such as loading and unloading of the workpiece and removal of chips. In addition, the workpiece should have good openness after installation, which will facilitate the centralized processing of the workpiece.

(2) Accurately position components. When the fixture is used to position the component, a two-pin positioning method should be adopted, and the distance between the diamond-shaped pin and the cylindrical pin in each set of components should be accurately located with reference to the actual size of the workpiece, so as to ensure that each moving component in the CNC milling machine is It can be moved to the correct position during processing.

(3) Improve the clamping method. For fixtures, the internal clamping elements should be as simple as possible, so that the tool will have more space for movement. In the design, multiple clamping pieces should be clamped at the same time by means of interlocking clamping. In the processing method, the CNC milling machine will usually be more concentrated, which will inevitably produce a large clamping force, leaving some indentation on the surface of the workpiece. In order to solve this problem, we can weld a layer of copper at the place where the platen contacts the workpiece.

(4) The fixture design of the vertical CNC milling machine. Unlike ordinary CNC milling machines, when the vertical CNC milling machine is processing, the chips often fall on the fixture. Therefore, when designing fixtures of a vertical CNC milling machine, it is necessary to consider the chip removal measures. When removing chips, the chips can not affect the automatic operation of the tool, nor can they fall on the surface of the components of the fixture, so as to ensure the high-precision positioning of the components.

3 Summary

In summary, the production of the CNC milling machine is inseparable from the fixture support, and the design quality of the fixture will directly affect the work efficiency of the CNC milling machine. The design content of tooling fixtures mainly includes three major aspects: fixing method, design process, and tool setting. Therefore, the improvement of tooling fixtures should start from these three aspects, adopting a design method of clamping multiple workpieces at one time, and using multiple pieces. Fixing fixtures instead of traditional fixtures can increase the working efficiency of CNC milling machines and make CNC milling machines truly sustainable.