In order to meet the requirements of the main drive of CNC lathe processing, CNC machine tools (attribute: automated machine tools) often use a motor stepless speed regulation system. The method of combining multi-level speed regulation realizes spindle speed regulation. In the numerical control processing, the control system issues instructions to make the tool perform various motions that meet the requirements, and the shape and size of the workpiece are expressed in the form of numbers and letters, and the processing required by the processing technology. It generally refers to the process of processing parts on CNC machine tools. In order to improve the degree of production automation, shorten the programming time and reduce the cost of CNC machining, a series of advanced CNC Swiss machining technologies have been developed and used in the aerospace industry.
1. Mechanical gear shift
In the main transmission system of CNC lathe processing, the traditional spindle box structure is greatly simplified due to the stepless speed regulation of the electric motor. However, due to the limitation of the spindle motor and the driving power supply, the output of constant torque is often in its low speed range. In order to enable the spindle to provide the maximum output power of the main motor within the entire speed range as much as possible, and to meet the needs of CNC machine tools (attributes: automated machine tools) for low-speed and powerful cutting, a combination of 1 to 4 gear speeds and stepless speed regulation is often used The method is the so-called stepless speed regulation in sections. The use of mechanical gearbox housing gear deceleration not only amplifies the output power, but also expands the range of speed regulation.
When CNC lathe processing is cutting, the spindle runs automotive parts at the speed specified by the S command in the part processing program. Therefore, there must be two types of spindle speed command signals in the numerical control system, that is, analog (definition: virtual of real things or processes) or digital signal S code to control the drive speed regulation circuit of the spindle motor, and at the same time use the switch signal (M code) to control the actuator of mechanical gear shifting and automatic shifting. The automatic shifting actuator is an electric-mechanical conversion device, commonly used hydraulic shift forks and electromagnetic clutches.
2. Motor speed regulation
The speed-regulating motors used for the spindle drive of CNC lathes are mainly divided into two categories: DC and AC.
(1) DC motor speed regulation-usually Axis CNC tools have a large speed regulation range, and the DC motor speed regulation adopts both voltage regulation and magnetic regulation. The characteristic curve of its typical DC spindle motor is shown in Figure 61. It can be seen from its characteristic curve that the motor below the speed n0 belongs to constant torque speed regulation, that is, it is realized by changing the armature voltage; above the speed n0, it belongs to the constant power (referring to the work done by the object in a unit of time). How much) Speed regulation is achieved by changing the excitation current.
The more commonly used FANUC DC-excited spindle motor uses a three-phase fully-controlled thyristor (zhá) tube non-circulating current reversible speed regulation system, which can realize voltage and magnetic speed regulation, and the speed range is 35. ?~3500r/min. CNC electronics machining General CNC machining usually refers to computer digital control precision machining, CNC machining lathe, CNC machining milling machine, CNC machining boring and milling machine, etc. The feed route of finishing is basically carried out along the part contour sequence. Therefore, the focus of determining the feed route is to determine the feed route of rough stainless steel machining and idle stroke.
(2) AC motor speed regulation
At present, cage induction motors are used in AC main shaft drives of CNC machine tools, and vector control frequency conversion speed regulation methods are widely used.
With the improvement of new DC and AC spindle speed control motors, motor speed control will be widely used. However, in order to reduce costs in economical CNC machine tool steel
(attributes: automated machine tools), mechanical gear shifting methods are often used. Change the spindle speed. In the numerical control processing, the control system issues instructions to make the tool perform various motions that meet the requirements, and the shape and size of the workpiece are expressed in the form of numbers and letters, and the processing required by the processing technology. It generally refers to the process of processing Iron parts on CNC machine tools. In order to improve the degree of production automation, shorten the programming time and reduce the cost of CNC steel machining, a series of advanced CNC machining technologies have been developed and used in the aerospace industry.
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