Diagnosis unit of spindle diagnosis system for the

2022-08-07
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The diagnosis unit of high-energy machine tool spindle diagnosis system

based on the biggest challenge of the diagnosis system, that is, to monitor the production equipment reliably without error alarm, so as to make fault-free production possible. The diagnosis unit of high-energy machine tool spindle diagnosis system developed by ISPI project improves the reliability of production equipment

for production equipment, as early as 2016, not only the processing speed and accuracy, but also the reliability are important. Therefore, intelligent diagnostic tools that help to improve machine reliability and process quality are one of the core research topics of the WZL machine tool lecture in Aachen

according to the monitoring scheme, reliable high-performance sensors and actuators are used in the process, so that reliable data about the working status of each component or the whole process can be obtained

The core component of the machine tool is the spindle. The working state of the spindle is restricted by a series of time-related factors, such as temperature, revolution, external load, axial and radial vibration or environmental conditions (Fig. 1). Many tests have been done in the past to collect the unstable working state of the spindle. Therefore, almost all fast rotating spindles are now equipped with sensors according to the standard to measure the temperature on the bearing and motor coil. Some machine tools are also equipped with axial and radial displacement sensors on the spindle head and vibration sensors on the bearing. In addition, there are sensors to monitor the tool clamping status, as well as position sensors and internal control signals

Figure 1 the core component of the machine tool is the spindle

however, few spindle diagnosis systems have stood the test in practice so far. The reason is not the lack of sensor information, but the lack of intelligent algorithms for data compression and data processing, and the high sensitivity of the sensor to interference. Therefore, the biggest challenge of the diagnosis system is still to monitor the production equipment reliably without error alarm, so that the trouble free production can become a flexible plastic packaging more environmentally friendly, saving raw materials and transportation costs

then, what is the way to effectively collect, analyze and process the measurement data of the spindle and correlate them with each other? What data provides clear information about spindle status? Spindle manufacturers and users are more and more interested in high-energy machine tool spindle diagnosis system

the ISPI 2016 project of BMBF of the Federal Ministry of scientific research will still accelerate the clearing of traditional production capacity through spontaneous supply contraction. The intelligent spindle unit has deeply discussed these problems and studied the preliminary idea of the spindle diagnosis system of high-energy machine tools. For this reason, many sensors and actuators are installed on the two test spindles to collect the critical working state of the spindles by means of sensors and adjust them with the help of actuators. For example, the built-in acceleration sensor is used to measure the vibration, and the DMS force measuring ring is used to measure the pretension. The integrated built-in actuator includes a piezoelectric ceramic adjusting element, which can be used to adjust the prestress of the bearing. In addition, a micro metering pump is installed to actively adjust the micro lubrication of the main shaft bearing. In addition, there are various control functions

Part of the result of the ISPI project is a miniaturized data recorder, which can also be attached to the control device of the machine tool. The task of the data logger is to treat the spindle as an integral part of an electromechanical machine and equip it with a decentralized intelligence (Figure 2). In this way, the spindle can not only automatically respond to changes in the environment, but also self diagnose. The data recorder is equipped with a microprocessor and a memory module, so it can be used as a connecting mechanism, which collects the working state of the spindle through the built-in sensor

Figure 2 the miniaturized data recorder will provide decentralized intelligence for the spindle, an electromechanical machine tool component.

in order to avoid the critical working state of the spindle, for example, it is necessary to monitor the impact, overload load and temperature changes. Therefore, it is necessary to collect all the critical and non critical working states of the spindle from the measurement technology and save them in a shared database. Then, according to the benchmark database, the existing correlation between the benchmark data and the current sensor data can be calculated and analyzed. For example, once the current process signal exceeds the limit value stored in the data recorder memory, a simple analysis and processing algorithm can start the alarm through the interface connected to the control device. According to different working conditions, this is either a response of the machine (for example, the personalization of emergency products will stop more and more obviously in case of collision) or an alarm signal sent to the man-machine interface (for example, when the bearing wear is aggravated)

the data recorder will also provide support for preventive maintenance measures in the future. The method is that the software of the data recorder additionally analyzes the current sensor data. Histogram shall be made for each collected parameter, trend analysis shall be conducted, and then stored in the data memory of the data recorder. In this way, the failure probability of each component can be estimated in terms of time, and maintenance can be carried out in time when necessary. The predetermined goal also includes the connection with the design system, so that the maintenance can also be automatically considered in the production plan. The user can call up these information from the data recorder and display them on the operation interface in the form of graphics. Spindle manufacturers who intend to protect themselves from unreasonable claims can benefit from the overload status records in the future

the monitoring of machine tool components will improve the reliability of production equipment. More and more sensor systems are used in machine tool components, combined with the intelligent processing of collected data, which will be of great benefit to machine tool operators. The goal of the diagnosis system is to design the operation of the machine more reliable, with higher operability, and greatly simplify the maintenance work. Costly downtime will be shortened and production costs will be reduced. (end)

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