What factors determine the accuracy of CNC machining accuracy?

CNC precision machining When the linear movement measurement of CNC machining is carried out, a linear inspection element is usually used, which is called a simple measurement. The closed-loop control of the position is called a full-closed-loop control. It is not affected by the transmission accuracy of the machine tool, because the linear displacement of the machine tool table has an exact proportional relationship with the torsion angle of the driving motor, so the technique of driving the motor or the torsion angle of the lead screw can be used to directly measure the moving distance of the worktable. , this technique is called indirect measurement, and the formed position closed-loop control is called semi-closed-loop control.

The measurement accuracy of CNC precision machining depends on the accuracy of inspection components and machine tool feed transmission chains. The machining accuracy of the closed-loop CNC machine tool is largely determined by the accuracy of the position inspection assembly. The CNC machine tool has very strict requirements on the position inspection components, and its resolution is usually between 0.001 and 0.01mm or less.

1. Requirements of the feed servo system for the position measurement assembly

The feed servo system has very high requirements for the position measurement assembly:

1) Less affected by temperature and humidity, reliable work, good accuracy retention and strong anti-interference ability.

2) It can meet the requirements of accuracy, speed and measurement limitations.

3) It is convenient to apply protection and adapt to the working environment of machine tools.

4) Low cost.

5) It is easy to realize high-speed dynamic and static measurement and punishment, and it is easy to realize automation.

Location inspection equipment can be divided into different varieties according to different classification techniques. According to the form of the output lamp, it can be divided into digital type and analog type; according to the example of measurement base point, it can be classified into incremental type and absolute type; according to the movement form of the position measuring element, it can be divided into reverse type and linear type.

2. Diagnosis and removal of inspection assembly failures

The probability of inspection component failure is relatively high compared with CNC assembly, and it often occurs that the cable is damaged and the components are dirty. damage, and the phenomenon of collision deformation. If it is suspected that the inspection component is faulty, you should start to check whether the cable is broken, stained, deformed, etc., and you can also determine the quality of the inspection component by measuring its output. This requires you to be proficient in the working principle and output of the inspection component. light sign. The following takes the SIEMENS system as an example to introduce.

(1) Input the light signal. The continuous relationship between the position control module of the SIEMENS CNC system and the position inspection device.

The output signal of the incremental torque measuring device or the linear device has two forms: the first one is a voltage or current sinusoidal signal, in which EXE is a pulse shaping interpolator; the second is TTL level light. Take the sine current output type grating scale of HEIDENHA1N company as an example, the grating is composed of grating scale, pulse shaping interpolator (EXE), cables and connectors.

During the movement of the machine tool, three sets of lights are output from the scanning unit: the two sets of incremental lights are generated by four photocells, and two photocells with a difference of 180° are connected together, and their push-pull Two sets of similar sine waves, Ie1 and Ie2 with a phase difference of 90° and an amplitude of about 11μA are formed. A set of reference lights is also connected to a push-pull form by two photocells with a difference of 180°, and the output is a spike light. Ie0, which has a useful weight of about 5.5μA, this light signal only occurs when it passes the fiducial mark. The so-called datum mark means that a magnet is installed on the shell of the grating ruler, and a reed switch is installed on the scanning unit. When the reed switch is close to the magnet, the reed switch is turned on, and the reference light signal can be output.

Dongguan Yifeng Metal Co., Ltd. as one who also teaches operations about how we use our whole operating system as a way to gain advantage and create considerable value and capture value in a sector where, in essence, the environment is quite hostile from a competitive point of view.
Dongguan Yifeng Metal Co., Ltd. will make a healthy profit for its owners and provide a rewarding work environment for its employees.
Dongguan Yifeng Metal Co., Ltd. is the best manufacturer which has rich experience on manufacturing.
Dongguan Yifeng Metal Co., Ltd. employs a numbers of citizens, helping them and their families achieve a higher standard of living.