Intellicass Systems for Sheet Metal Stamping

Intellicass (www.intellicass.com) develops advanced systems and technology to radically improve the efficiency of the sheet metal stamping process. These systems enable highly efficient try-out in die construction for stamped parts, in addition to providing many benefits in mass production. Try-out is the stage in which the shape of the die is fine-tuned to create a stamped part that meets quality specifications.

Quite often during try-out, the part is formed with splits and/or wrinkles or other defects such as excessive thinning. The conventional approach to correcting these defects is to "work" the die, that is, grind or weld various parts of the die to change the material flow during the stamping cycle. This is a time consuming, labor intensive process which requires a lot of experience and skill, especially for lightweight hard-to-form materials that are used for fuel-efficient vehicles. The system also compensates for operational variations during mass production of stamped parts, ensuring consistent part quality and thus reducing scrap.

The Challenge

Intellicass is using the concept of adjusting binder forces (i.e. the forces that hold the sheet-metal blank) to correct these defects. The idea is simply explained as follows: if the part has a split, the binder forces are locally reduced allowing more material flow and thus eliminating the split; if the part has a wrinkle, the binder forces nearby are tightened up, thus effectively stretching out the wrinkle. By adjusting the binder forces locally using a computer-controlled binder force varying system, defects can be corrected rapidly and reduce try-out time by up to 80%.

The company’s current focus is in the area of developing cost-effective variable binder-force systems, which enable local control of binder forces during the forming cycle using computer-controlled hydraulic cylinders.
 

The Opal-RT Solution

An Opal-RT Real-Time Controller forms the basis of the Intellicass control system, acquiring measured data from sensors and commanding servo-valves. As shown in Figure 1, using a software layer (i.e., Python), the Opal-RT system, which is connected to the process variables, is interfaced with a laptop computer which has RT-LAB installed.

1. First, an Excel template is used to input pre-determined binder forces for the hydraulic actuators to the software layer.
2. Second, all system conditions (e.g., hydraulic pressure and punch force offsets, implemented controller gains, etc) are monitored and also modified using a GUI built in LabView and run on Opal-RT’s TestDrive testing software platform.
3. Third, the process controller, developed in collaboration with the University of Michigan in Ann Arbor and Opal-RT, is prototyped in Simulink, compiled using RT-LAB, and then implemented on the Opal-RT target machine through the software layer.
4. Finally, the acquired data (e.g., binder force and punch force) are collected using the Opal-RT target, and then communicated to the RT-LAB equipped laptop computer. A sample rate of 2 kHz is used for both data acquisition and the inner hydraulic control loop. However, the process controller that determines the desired binder forces executes at a sample rate of 100 Hz.

Results

The Intellicass system provides a wide variety of benefits to its users.
These include:

• Up to 80% reduction in try-out time (from reduced bead and die-work, elimination of binder spotting and EQ block adjustment)
• Significant reduction in the Finite Element Analysis simulation effort  needed to fine tune die-design
• Reduced press-wear from lower impact forces
• Reduced spring-back obtained by increasing binder forces at the end of the forming cycle
• Savings of $1,000/hour in production runs from material savings and scrap reduction