What are the characteristics of the transmission system and drive mechanism of CNC machine tools?

Intelligent manufacturing has become the general trend of the manufacturing industry, and the popularity of CNC machine tools is also deepening. So compared with ordinary machine tools, what are the characteristics of the transmission system and drive mechanism of CNC machine tools?

Let's start with the transmission pair - the mechanical transmission pair of ordinary machine tools generally has the following types:

1. Belt drive: except for the synchronous toothed belt, it relies on friction transmission, has a simple structure, is easy to manufacture, and has low cost. It will slip during overload and can play an overload protection role. The disadvantage of belt drive is that there is slippage, and it cannot be used in occasions where the speed ratio requires accuracy. Application example: the main motor drives the lathe spindle.

2. Gear drive: The structure is simple and compact, can transmit a large torque, can adapt to variable speed and variable load work, and is widely used. Its disadvantage is that the linear speed cannot be too high. Gear drive is currently the most widely used transmission method in machine tools. Application example: high torque spindle transmission mechanism.

3. Worm gear drive: The worm is the active part, and its rotation is transmitted to the worm wheel. This transmission method can only be driven by the worm, and vice versa. Application example: rotating mechanism of horizontal milling machine table.

4. Gear rack transmission: the gear rotates, and the rack moves linearly accordingly. Application example: heavy gantry feed shaft drive.

5. Screw transmission: spiral transmission, a mechanical transmission that uses the meshing of the screw and the nut to transmit power and motion. It is mainly used to convert rotational motion into linear motion and torque into thrust. Application example: lead screw transmission, general lathe is used to turn threads.

Common CNC machine tool transmission pairs include the above five transmission pairs that have been precipitated for a long time. With the advancement of science and technology, CNC machine tools have begun to pursue high speed, high precision, and high rigidity, and a number of advanced transmission pairs have been born.

1. Electric spindle: The emergence of electric spindles has eliminated the pulley drive and gear drive in the main transmission system of high-speed CNC machine tools. The machine tool spindle is directly driven by a built-in motor, thereby shortening the length of the machine tool main transmission chain to zero, realizing the "zero transmission" of the machine tool.

2. Linear motor: A transmission device that directly converts electrical energy into linear motion mechanical energy without any intermediate conversion mechanism. It can be regarded as a rotating motor cut radially and unfolded into a plane. Some of the rotary tables in the horizontal machining center now also use the motor direct drive method.

3. Elastic coupling: This is more traditional. The elastic coupling uses a parallel or spiral grooving system to adapt to various deviations and transmit torque. Elastic couplings usually have good performance and price advantages. In many practical applications of stepping and servo systems, elastic couplings are the best products. The one-piece design enables the elastic coupling to transmit torque with zero clearance.

4. Roller cam mechanism: The cam divider is a mechanism for achieving intermittent motion. It has the remarkable characteristics of high indexing accuracy, smooth operation, large torque transmission, self-locking during positioning, compact structure, small size, low noise, good high-speed performance, and long life. Application and workbench exchange or tool changing mechanism.