On a new install, the tech had much difficulty in running the line without receiving Continuous Press Miss-feed Errors. We were unable to get to the root cause of the issue due to time constraints. When testing on the PC simulator we also saw an intermittent problem. We decided to review all of the feed profile calculations for accuracy and a few things were found that may or may not explain what was happening at the customer.

The calculation that determined when a triangular profile vs a trapezoidal profile could be used assumed that the press provided enough time such that the maximum velocity could be reached using the programmed acceleration.

Trapezoidal move calculations were being made using the result of the prior incorrect calculation.

The trapezoidal calculation method was also determined to be incorrect. It attempted to adjust only the acceleration. It appeared to work under the test conditions but it was mathematically unsound and did not achieve consistent results.

A new simpler, accurate, method was used. The actual move velocity can be calculated using the Maximum Velocity and a proportional relationship between the required move and the Maximum Cont Press Move. The acceleration rate can be calculated using the actual move velocity and the time under acceleration during a Maximum Cont Press Move. Using the same acceleration and constant velocity times as a Max Cont Press Move is what allows the proportional velocity and acceleration rate calculations to be mathematically sound. This achieves very consistent results.