Rotary transfer tester for interlock solenoids (LabVIEW framework)

Project Description

The major project task comprised the development of a tester system for proportional interlock solenoids, which primarily consisted of a rotary table offering six test stations. The tester system had to be designed based on NOFFZ UTP 9085 concept which already comprises protective coating, monitored openings for maintenance and an integrated 19″ rack for measurement and test equipment as well as a central IPC.

The basic UTP 9085 system had to be equipped with suitable measurement devices and power supplies in order to become a scalable and modular tester system for a whole product family including all its future variants. The test sequence had to be implemented using LabVIEW or CVI by National Instruments.

The test station had to be designed for manual fitting with components so that additional facilities for prohibiting access to the rotary table while testing is in progress became necessary.

In addition to that, the tester had to check if DUTs had been properly placed before the actual test cycle starts. Cycle times had to be less than 15 seconds. Test sequences had to be chosen via ident numbers. Measurement results had to be stored in accordance with the customer’s standard procedure. Fast and easy exchange of any tools for additional variants had to be guaranteed.

Implementation and challenge

This project’s main challenge has been presented by the development of a rotary transfer tester based on NOFFZ UTP9085 concept involving numerous hardware components and software modules which have been exactly specified and predefined by the customer. In particular, image processing by means of Ascentics Video Lab (SW) and Vision4rail (HW Server) had to be integrated into the LabVIEW framework.

The whole test sequence had to be implemented based on NOFFZ’s LabVIEW framework for the UTP 9065 rotary table concept. The main user interface had to provide an indicator which informs about the current operational state of the DUTs, indicates the actual machine operator and the current product type. This interface also had to grant access to functions such as system and module settings, user management, measurement and analysis. Measurement equipment integrated into the UTP 9085 rotary table tester primarily consisted of a robust and powerful NOFFZ industrial PC, a central measurement core for force, distance and voltage measurement, an NI PCI 6221 multifunctional data acquisition module providing numerous digital I/O channels as well as a Leibinger Jet 3 for imprinting DUTs. A Siemens S7 PLC is responsible for controlling the rotary table. Connectivity to the measurement equipment has been established by means of NetLinkPro. The design for the new tester had to consider the following test steps:

  1. Caulking control
  2. optical bonding control using two cameras
  3. spring characteristics evaluation
  4. Current/distance diagram recording
  5. Automatic discharge of NIO parts
  6. Imprinting IO labels and storing measurement results with respect to the serial number.

According to these requirements, the six test stations of the rotary table and their components have been implemented as follows:

  • Insert DUT/remove IO parts (light curtain, DUT and DUT position recognition)
  • current/distance diagram recording (pneumatic contacting, fitting for a µ-Epsilon sensor conducting contact-free distance measurement)
  • spring characteristics evaluation (pneumatic drive moving distance and force sensors)
  • Caulking control (optical bonding control by means of two cameras)
  • Printing/Scanning (rotatable clutch removes DUTs from rotary table, electrical SMC drive moves clutch into printing and scanning positions)
  • discharging of NIO parts (via chute)

Production orders consisting of order number and product type can be created, started, paused and closed by means of the user interface which also provides an editor for creating, modifying and deleting product variants. An optional module allows storing report data directly into the customer’s data base by means of a .dll which has been provided by the customer. Report data includes ID, serial number, general IO/NIO tag and results of all measurements. In order to achieve an optimum general view, the user interface module provides features for viewing status and intermediate results of all steps and all modules which are currently fixed to the rotary table.

Conclusion

Based on the universal, versatile NOFFZ UTP 9085 tester platform a customized tester solution for interlock solenoids offering nearly total test coverage has been developed and implemented.

The new system can flexibly adapt to all variants of the product family and provides automatic DUT detection. Due to its flexible hardware and software structure it modifications and expansions can comfortably performed.

The next stage of expansion for the tester comprises an additional printer which allows for more flexible imprinting of the DUTs either with black or white labels. Future retooling for new product families requires only exchanging the module mounting and parameterizing the software.