Measured Force on the Chain

There are many advantages to digital measurement technology

When it became necessary to upgrade one of the calibration machines, the decision was made at Ketten Wälder to convert the measurement technology to modern digital technology. They now use a digital amplifier of the MP85A type, from HBM. A ring force transducer of type KMR, with a nominal (rated) force of 400 kN, measures the force applied by the hydraulic cylinder. The force transducer complies with high degree of protection IP67, and is therefore also suitable for use in harsh environmental conditions. The stainless steel housing makes it resistant to environmental influences. Because the transducer is ring-shaped, it is ideal for integration into the machine force flow. The good reproducibility of the force measurement ensures safe and reliable results. The MP85A amplifier is specifically designed for quality control applications in the production process, and has a microprocessor and relevant algorithms, so that measured values are already analyzed internally. The amplifier records the force response during the process, and checks whether the maximum force achieved lies within a given window, using this as the basis for making the “OK/Not OK” decision. If there is an error, because the maximum force is too low, for example, the amplifier stops the process immediately. “It was particularly important to us when retrofitting the calibration machine that we were also able to log the measured force values”, said Reimar Bürkmayer, naming one of the main requirements that had to be met by the new measurement system. The amplifier has an integrated Ethernet interface, over which the measured force values are transferred to a control PC, where they are displayed. A graphical realization of the force response while the chain section is being extended by force, illustrates at a glance whether the process is running correctly. The maximum value that is reached each time is stored in a database. Saving these values is particularly important with regard to ensuring complete traceability. It would not have been difficult to save the entire force response, either. “But this is not necessary for our application”, explains Reimar Bürkmayer. “We keep the volume of data to a minimum, by only saving the maximum value each time.”

Upgrading old analog technology

When the calibration machine was due to be upgraded, Ketten Wälder had a good look round the market to see what was available. Some of the old analog measurement technology also came from HBM, so they were again asked about relevant, modern solutions. “We meticulously compared proposals from different companies with one another, and ultimately decided on HBM, because this gave us the best price/performance ratio”, is how Reimar Bürkmayer justified the decision to choose HBM as their supplier. Together with the hardware – that is, the force transducer and the amplifier – HBM also supplied the Industry Monitor software package. This application is based on Microsoft .Net, and visualizes the measured force values on the industrial PC connected via Ethernet with TCP/IP. HBM was also responsible for programming a relevant application to store the measured data in a database. The software has a user-friendly input screen, in which the type of chain that is currently being processed in the calibration machine can be selected from a list. The user must then also enter the relevant batch number. The software automatically creates the files for storing the measured values. The quality data of every chain that leaves the company can thus be reliably traced. “HBM had no problem at all programming the individual application, and overall, we are very satisfied”, is how Reimar Bürkmayer summarized the experience gained from the project. The other calibration machines at Ketten Wälder will gradually be fitted with modern digital measurement technology as well, now.