A lot has changed in the area of lighting technology since the first motorized "carriages" took to the road. At the dawn of automotive history, it was normal to have lamps either mounted on the side of the vehicle or on the hood. Later, these were replaced by electrically-operated lights. With the lamps, you could literally refer to them as "fire points", derived from the light source, usually acetylene flame lamps, that were actually burning.
Equipment for switching from main beam to low beam was designed in 1908: Using a Bowden cable, you could operate a lever that shifted the gas flame from the fire point of the reflector. The world looks very different a century or so later - "and there was light". With new technologies and powerful LED lamps, these days we are, in the full sense of the word, "light years" ahead. This however has called for innovative semi- or fully-automated production systems, in order to guarantee the precision needed for the manufacture of these sensitive vehicle parts. This was an exercise for the experienced plant engineers at Vescon.
Vescon Systemtechnik GmbH is headquartered in Gleisdorf, near Graz, Austria. Here, the company implements a wide range of projects from automation and process engineering right up to power engineering and software development. One of these sophisticated automation and process engineering solutions that was developed specially for the Slovakian plant of Tier 1 supplier ZKW Group, was for the production of full LED headlights. The solution is an LED light module that avoids dazzling other road users thanks to a "matrix arrangement" of the LEDs and the ability to dip individual LED segments, while at the same time ensuring good visibility for the road ahead.
Visual sensors identify the presence of oncoming traffic or vehicles ahead and the segments are selectively switched on or off, depending on the traffic conditions. Coordinated transitions between the light scenarios mean that the driver enjoys a homogeneous and optimized illumination of the road, without that sudden change of light that we are used to when switching from main to dipped beam. The driver's eyes can adjust to the new light setting more easily. This represents an active safety plus because the rest of the surroundings remain well lit by the main beam.
The design had to take processes such as the tricky application of a two-component thermally conductive paste into account. Christoph Legat, Project Manager at Vescon Systemtechnik GmbH: "The paste has very rapid hardening properties. At the design stage we had to ensure that the process would not cause the so-called pot life to be exceeded. This defines how long a reactive material can be processed or, as in this case, how long the LED components can be repositioned in the paste before the material has hardened too much."
Thermally conductive paste is used here because powerful LEDs produce heat that has to be dissipated. With finished headlight modules, additional small fans also ensure that the heat is diverted towards the front of the headlight, which supports the deicing and defrosting properties of the headlight. "It is important to check whether the correct amount of heat-conducting paste has actually been applied to all required surfaces as otherwise, partial overheating can occur. Without doubt, this is one of the main challenges we were faced with, with this system," says Project Manager Legat.
A second, particularly challenging part of the headlight assembly system is the hot riveting. A plastic dome is deformed at a precisely determined temperature to create a rivet head. Christoph Legat: "This rivet head sits on the reflector and it has to hold it and the printed circuit board on the cooling element, completely securely and reliably. The riveting has to be so accurate that no gap can occur, which could cause the components to wobble during the subsequent vibration test or under normal operating conditions. In the worst case, this could impact on the illumination while driving."
The customer opted for a semi-automatic solution where multiple operators are involved. On the one hand, this opened up the opportunity for greater flexibility while keeping costs down. On the other, it made it easier for the manufacturer to take different components or product versions into consideration. In spite of the manual interventions, the complete system is monitored at every step by a controller. Primary control is done through a database that manages all the product data and information relating to the production process of each headlight. At the end of the manufacturing process, each headlight is fully traceable.
As the first step of the process, the operator removes the headlight housing and places it in the processing station. Then the type code or the variant that is to be produced is selected. "A good example is a headlight that is intended for a vehicle that is exported to other, non-European markets. In such cases, other indicator modules are sometimes used because local statutory regulations define that there must be switching between the indicator and the daytime running light," explains Legat.
每个操作员在两个或三个不同的装配工位上工作，同时锁紧气缸以确保将工件牢固地固定到位。这不仅可以将它们固定在适当的位置，而且，只有在正确执行了所有必要的处理步骤后，它们才释放组件。操作员随头灯放置不同的组件，直至其到达第一个全自动处理站，即涂上导热膏。到达该位置后，头灯已经完全连接好，并且已经安装了调节系统和远光灯模块。现在，Vescon已经部署了由 Festo 技术和应用中心的专家交付的交钥匙三轴抓取系统。
基本轴是两个齿形带式电缸 EGC-120，行程为 250 ，通过连接阀杆和节省空间的直角减速机进行同步。y 轴使用重负载电缸 EGC-HD-160-TB（坚固，带双导轨）。在 z 轴上，使用滑台电缸 EGSL-BS-75 执行工作（行程为 100，带滚珠轴承笼式导轨的丝杆电缸）。所有轴均配有伺服驱动器套件。具有 PROFIBUS 接口和安全模块的三种类型的 CMMP-M3 主电机控制器作为控制器运行。Festo 建立并提供完整的即可安装抓取系统——并提供性能保证和文档。
即装安装的抓取系统确保双组分导热膏的均匀涂抹。
操作员将散热器（带有用于插入反射镜的孔）放置在工作站中，并使用 Festo 抓取系统在两侧自动涂抹导热膏。抓取系统始终将双组分分配系统带到正确的轨道上的正确位置。在下一步中，将带有五个 LED 的印刷电路板放置在散热器上的导热膏中。然后使用反射器及其导向销，确保最佳定位。完成此操作后，操作员将整个散热器卸下，然后将其带到下一个工位，另外的 Festo 抓取系统将负责铆钉头工具的运动。
在这里，有两个带导向滑块的齿形带式电缸 EGC-80 ，它们通过一个连接阀杆和一个节省空间的直角减速机（x 轴）实现同步。还有一个重负载电缸 EGC-HD-160-BS （坚固，带双导轨，y 轴）和 PLFN 型法兰齿轮。所有轴均配备带有多圈编码器的伺服驱动器组件。
项目经理 Legat 对即可安装的解决方案感到满意：“我们只需要提供所需特性的详细信息，定义负载以及必须行进的路径或轨道，然后就不必再思考这一部分了。这不仅在极大程度上简化了我们的工作，而且能够将 Festo 为我们提供的抓取系统 CAD 数据用于整个系统的设计。”
安装在抓取系统上的铆钉头工具通过由 VTUG 控制的 ADN 气缸移开。使用位于气缸上的 SMAT 位置传感器，在铆接之前检查反射器上的销钉长度以及正确的最终位置。如果销钉的长度正确，则可用铆钉头工具将凸出端加热重塑为铆钉头。这样可以建立永久连接，因此在汽车的整个使用寿命中都能够将灵敏的零部件始终保持在适当的位置。现在，由散热器、PCB 和铆接的反射镜组成的完整组件将由操作员卸下，并内置到头灯中。
为了测试组件是否已牢固地固定到位，头灯将进入拉力测试站，在拉力测试站中，旋转和直线驱动的钩子位于模块下方，并通过拉力测试松紧度。然后进入调光站。操作员将头灯放在转盘上。将头灯夹紧到位，将转盘旋转到工作位置。然后连接头灯，并使用摄像头测试各种照明场景和指示器模块。此外，还将检查照明模块的正确位置，并像在汽车车间中那样将其设置为理想水平。
然后，安装设计面板来隐藏所有技术，并在胶合盒中使用无硅热熔胶将头灯前部的外部透明透镜胶合到位。这是一个时间关键型的过程，因为只能在特定时间内以最佳方式将零件粘合在一起。经过一段时间的预热以减小表面张力，并涂抹胶水后，机器人将镜头与头灯外壳按压到一起。 之后在头灯上进行泄漏测试。如果该装置通过了最终测试，则意味着又一个创新的“光之使者”已准备好开启在世界各地的旅程。