Developing of smart servo sheet metal forming tool

The main result from the project SmartMforming will be developed method for manufacturing Smart servo sheet metal forming tools. Conventional way of producing sheet metal parts is described next. First operations are usually cutting operations where the right dimensions of the blank are cut. Deep drawing or bending forming processes follows. The last operations are there to ensure right dimensions and tolerances and are called calibration operations. The idea of this project is to include servo systems and improve the whole forming process in order to complete following tasks:

1. Implement variable punch speed in sheet metal forming in order to optimize product quality

Variable punch speed and consequently variable strain rate has a big influence on the quality of the sheet metal parts. In the past, a number of studies were performed to deal with the dependence between the actual strain rates and forming behavior of sheet metals. All findings reinforce the actual need for a detailed investigation of deformation rates in sheet metal process. In current mechanical and hydraulic presses it is impossible to regulate forming speed during the process. The only think that can be changed is stroke rate, but otherwise the speed of the press is as it is. In servo presses forming speed is fully programmable and can be changed in any moment during the sheet metal forming process. Therefore the use of servo press is very useful but unfortunately not anyone can afford them. Therefore we are presenting idea of using servo systems in sheet metal tools. In these cases servo systems regulate forming speed and the sheet metal process can be made in almost any press. Our idea is to show that with variable forming speed it is possible to reduce spring-back and improve formability of sheet material.

2. Compensation of spring-back with servo system

With variable forming speed it is possible to reduce spring-back to get high quality product, however not in all cases. Therefore it is still needed to align the part in order to get right dimensions and tolerances. In this cases cams driven by servo systems can be used in sheet metal forming. The problem with the current approach is that cams have fixed velocity profile and stroke what means no flexibility. This means more problems and reworks in tryouts of tools and if the process parameters, environment or sheet material are changed it is necessary to repeat optimization loop and re-machine the sheet metal forming tool. With use of the servo system velocity and stroke can be changed at any time. Therefore the later optimization is much faster and easier without need to re-machine the tool even the process parameters, environment or sheet material changed significantly.

3. Merging two or more forming operations into one

Merging more operations in one is always R&D engineer`s most important task. It means that at the end the tool will have fewer operations, which means shorter tool, less material, lower weight of tool and consequently less manufacturing costs. With conventional methods this became very difficult to be done, but with use of servo systems this can become reality.

4. Developing tool lifetime control of the sheet metal tools by using sensors and intelligent systems

Sheet metal forming tools are made to make millions of parts in their lifetime. Therefore during this time it is necessary to maintain the status of the tool, specially critical parts. Among those critical parts belongs also elements needed for piercing and cutting. With integrated sensors, connected to the smart system it could be possible to analyze stresses and forces during the cutting process and in predict remaining lifetime of the critical tool parts. The intelligent system is going to be connected to the Ethernet so that maintenance team in the company can get warnings and plan maintenances work accordingly.