Learning Some CNC Machining Center Knowledge

The machining center is a digitally controlled machine tool with a tool magazine, which can automatically change tools and perform multi-process machining of workpieces.

After the workpiece is clamped once, the digital control system can control the machine tool to automatically select and replace the tool according to different processes, automatically change the machine tool spindle speed, feed rate, tool movement path relative to the workpiece and other auxiliary functions, and complete several surfaces of the workpiece in sequence. Machining on multiple processes.

Due to the concentration of processes and automatic tool change, the machining center reduces the time of workpiece clamping, measurement and machine tool adjustment, etc., so that the cutting time of the machine tool reaches about 80% of the start-up time of the machine tool (only 15-20% for ordinary machine tools) It also reduces the time of workpiece turnover, handling and storage between processes, shortens the production cycle, and has obvious economic effects. The machining center is suitable for small and medium batch production with complex parts, high precision and frequent product replacement.

The first machining center was first developed in 1958 by the American Carney-Trake company. It adds an automatic tool changer on the basis of the CNC horizontal boring and milling machine, so that it can perform centralized machining of milling, drilling, boring, reaming and tapping after the workpiece is clamped once.

Since the 1970s, the machining center has developed rapidly. An interchangeable spindle box machining center has emerged. It is equipped with multiple multi-axis spindle boxes equipped with tools that can be replaced automatically, and can perform porous machining on the workpiece at the same time.

This form of multi-process centralized machining has also been extended to other types of CNC machine tools, such as turning centers. It is equipped with multiple automatic tool changers on a CNC lathe and can control more than three coordinates. In addition to turning, the spindle can be stopped Or indexing, and the process of milling, drilling, reaming and tapping by tool rotation is suitable for machining complex rotating body parts.

Machining centers are divided into vertical and horizontal types according to the arrangement of the main shaft. The horizontal machining center generally has an indexing turntable or a numerical control turntable, which can process all sides of the workpiece; it can also be used for joint movement of multiple coordinates in order to process complex space curved surfaces. Vertical machining centers generally do not have a turntable, only for top surface machining. In addition, there are composite machining centers with vertical and horizontal spindles, and vertical and horizontal adjustable machining centers with spindles that can be adjusted to horizontal or vertical axes. They can process five faces of the workpiece.

The automatic tool changer of the machining center is composed of a tool magazine and tool change mechanism for storing tools. There are many types of tool magazines, the common ones are disc type and chain type. The capacity of the chain knife stock is larger.

The tool changer mechanism exchanges tools between the machine tool spindle and the tool magazine, the common one is a manipulator; there are also those without a manipulator and the main spindle directly exchanges tools with the tool magazine, called armless tool changer.

In order to further shorten the non-cutting time, some machining centers are equipped with two pallets that automatically exchange workpieces. One is loaded with workpieces to be processed on the worktable, and the other is loaded and unloaded outside the worktable. After the machine tool completes the machining cycle, it automatically exchanges the pallets, so that the time for loading and unloading the workpiece coincides with the cutting process.

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