摘要
电阻焊技术自发明以来,由于其能量集中、变形量小、辅助工序少、不须添加填充材料、生产效率高、操作简单和容易实现自动化等优越性,得到了突飞猛进的发展,其中电阻点焊是最常用的电阻焊技术之一。由于电阻点焊的焊接过程是一个高度非线性、多变量耦合作用并伴随大量的随机因素的动态热过程,因此对电阻点焊过程焊接参数进行实时监控是焊接质量的重要保障。在焊接监控过程的信号传输中通常采用有线传输技术,然而有线传输在实际应用中会带来布线困难以及安全隐患等众多问题,无线传输技术能够很好地解决这些难题,与此同时采用无线传输技术在很大程度上提高了生产效率,降低了生产成本。采用无线通信技术进行监测,技术人员可以安全方便的远程监测并控制生产系统和焊接设备的运行状态及参数。
针对电阻点焊实际生产对焊接参数的实时监控的要求,以及无线信号传输较有线传输的突出优势,本文研究了基于ZigBee协议的无线网络的点焊监测系统。系统使用的下位机为单片机,用以对焊接电流、焊接电压及电极压力等焊接参数进行数据采集、处理,用工业PC机作为系统上位机,对下位机发送的数据进行显示及存储,上位机与下位机之间通过ZigBee无线模块实现无线通信。整个监测系统具有对点焊过程焊接参数的采集、处理、存储及无线传送等主要功能。
论文使用CYGNAL公司的C8051F020单片机作为下位机的中心控制单元,它与电流传感器、电压传感器、压力传感器、信号调理板、外接存储器及无线模块共同构成下位机。本文使用Keil μVision2对下位机进行程序编译,实现了下位机对焊接参数的数据采集、处理及存储。上位机使用Visual C++6.0进行主程序界面设计开发,完成对下位机发送的数据进行进一步处理及存储,并显示相应焊接参数的波形和焊接时间,可以对焊接参数实时表征。
本文选用Jennic公司基于ZigBee PRO技术的JN5148无线模块进行上位机和下位机之间的无线通信。ZigBee是新兴的一种短距离低速率无线通信技术,具有低功耗、低成本、组网灵活及高可靠性等优势。本文主要研究了基于ZigBee技术的无线网络的组建及无线模块的程序设计,实现了上位机与下位机之间的无线通信,并对无线通信能力进行测试,测试表明系统的无线通信能力可以保证监测系统对焊接过程的实时监测。
通过对监测系统的测试可以发现本系统对焊接参数具有较强的实时监测能力,该系统具有稳定性强、成本低、维护方便等特点,尤其是在恶劣的工厂环境中更能体现出其优势,可以用在汽车、轮船及航空航天等工业领域,能提高电阻点焊生产效率及焊接质量,可以为电阻点焊在实际生产中的应用提供更切实的帮助。
Resistance welding technology has got rapidly developed in recently years, due to theadvantage of its concentration of energy, small deformation, few auxiliary processes, noaddition of filler material, high efficiency and easy to realize automation. Resistance spotwelding is one of the most commonly used resistance welding technology. The process ofresistance welding is a non-linear, multi-variable coupling, complex and dynamic thermalprocess, and it includes large number of random factors process. In order to ensure qualityof welding quality real-time monitoring must be conducted. The signal transmission of thewelding process monitoring system usually use wire transmission, which will bring a lot ofquestions such as wiring difficulties and security risks. And wireless transmissiontechnology would be a good solution to the problem. Moreover, using the wirelesstransmission technology will improve production efficiency greatly, and reduce theproduction cost clearly. Using the wireless transmission to monitor the welding process, thestaff can remotely monitor and control the production systems and welding equipmentoperating parameters safely and comfortably.
To meet the demand of the real-time monitor and control of the welding parameters,and taking into account the outstanding advantage of wireless transmission, in this paper thewireless network system based on ZigBee protocol for resistance spot welding productionhas been researched. The system uses MCU as the lower computer, to collect and processthe data of the welding information, such as welding current, welding voltage and electrodepressure information. At the same time, the system uses industrial personal computer as theupper computer, to display and store the parameters transmitted from the lower computer.The wireless communication between the upper and lower computer is complied by ZigBeewireless module. The system has the main functions of the collection processing display,storage and wireless transmission of the parameters in the spot welding process.
In this paper, C8051F020MCU is used as the central control unit of the lowercomputer, and combined with current sensors, voltage sensors, pressure sensors, signal conditioning board, external memory and wireless module constitute the lower computer.Keil μVision2is used to conduct to comply the program of the lower computer, to collectprocess and store the welding parameters. The upper computer uses Visual C++to conductthe design of the main program interface, to process and store the data transmitted by thelower computer further. Moreover, the upper computer displays the wave from and weldingtime corresponding to the welding parameters, which will be able to reflect a series ofparameters of the welding scene in real-time.
In this paper, the communication between the upper and lower computer wascompleted by JN5148wireless module, which is based on ZigBee PRO technology. ZigBeeis the emerging,short-distant and low-rate wireless communication technology, which hassome advantages of low power, low cost, flexible networking and high reliability. The papermainly researched on the formation of the wireless netwok based on the ZigBee technologyand the design of program for the wireless module; and carried out the wirelesscommunication between the upper and lower computer, then the capabilities of the wirelesswas tested. The result indicates that the capabilities of the wireless communication can meetthe requirement of monitor the welding process in real-time.
Compared with the parameters measured by corresponding instruments in fact withthat monitored by this system, it can be seen that the system has high accuracy and goodwaveform display, as well as the good ability to monitor the welding parameters in real time.The system has the advantage of good stability, high accuracy, low cost and easy tomaintain, especially in the harsh factory environments would reflect the advantage of thesystem better. The system can be used in automobile, steamship aerospace and otherindustries’ field, to improve the production efficiency and welding quality of the resistancespot welding. And the system can make the resistance spot welding applied more effectivelyin the actual production.
引文
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