Tasks

Universal mechanical presses are highly flexible. They are suitable for both cutting at high stroke rates (100 to 2000 strokes/min) and for forming. In combination with individual, follow-on, connecting and transfer tools, they provide a wide spectrum of application options for the manufacture of small to medium-sized parts.

The following features are required of the control system from the viewpoint of the plant operator:

• Easy and convenient operation of the press and of the complete plant
• Fast, accurate set-up for new production parts
• Protection of operating personnel and press tools
• Early detection and prevention of faults
• Integration of the press in total plants

The following features are required of the control system from the viewpoint of the press manufacturer:

• Shorter configuring and start-up times
• Flexibility and modular design right across the complete machine spectrum

Solutions

The Press2000 control concept provides solutions that meet these requirements.

Press2000
The system platform is the SIMATIC S7-300 family. The PLC meets the requirements of the machine control system, such as interlocks, logic operations and releases. A performance-graded range of CPUs is available.

Function modules (FM) are used to implement standard technological tasks, such as cam control or axis positioning.

The FM 352 function module is an electronic cam controller with up to 32 cam tracks, some of which can actuate final control elements via direct outputs or be interconnected via the machine program. Distance/distance, distance/time, counting cams and dynamic cams are available for the various applications. These functions are implemented on an ASIC for the fastest response times.

The FM 351 and FM 354 function modules or SIMOVERTMASTERDRIVES MC can be used to control positioning axes by means of limit points or position control, depending on the required precision and sophistication of the drive system. These function modules control the punch height, sheet entry height or further positioning axes. Measurement systems which can be connected include SSI absolute value encoders or incremental encoders.

Press-specific software is available for technological tasks not covered by standard modules. Press-specific technology functions are, for example, the main drive control, the press-specific cam controller supply (FM 352), tool protection and press force monitoring. Depending on requirements with regard to performance and functionality, the technology software is available in two versions: Press2000S (a STEP7 solution) or Press2000M7 on the SIMATIC M7 automation computer. The SIMATIC M7-FM 356 automation computer with interface modules (IF modules) and the RMOS real-time multi-tasking operating system is particularly suitable for time-critical functions.

SIMATIC HMI operator panels are used for visualization, operation, fault diagnostics, parameter assignment and start-up support. An integrated range of units is available, from simple plain text displays to graphics-capable panels using TFT technology. All of the panels can be configured with the ProTool engineering system.

The different requirements in respect of the degree of automation are illustrated below by examples of various configurations.

Single-acting presses with fixed stroke height, cam controller and plain text display, can generally be implemented with a pure PLC and the FM 352 cam controller. Simple technological tasks, such as speed setpoint commands for the main drive, determination of the braking angle, TDC stop or simple process control are performed by Press2000S in the PLC user program. For example, the TDC braking angle is determined on the PLC by calculation, and is transferred to the cam controller for switching off the TDC.

For a higher degree of automation in terms of control axes, the above concept is expanded with FMs or SIMOVERT MASTERDRIVES MC. If necessary, a CPU with larger memory and PROFIBUS interface should be used.

For high demands on main drive positioning using the position controller for stroke height adjustment and fast process control with scan times of 2 ms-3 ms, the above design is extended with the Press2000M7 module.

Press2000 Software
The Press2000 software offers the following important functions, with differences in scope and performance between Press2000S and Press2000M7:

Technology functions

• Main drive control
  The main functions implemented in this software module are stroke number definition; dynamic braking angle calculation for TDC stop; main drive positioning using either position control or limit points for stroke height adjustment; and counters (e.g. batch, total and press force limit violation counters)
• Tool protection
  A wide variety of monitoring functions, such as static control, feed control and segment counting with or without position control are provided to protect the equipment from mispunching. If the predefined signal sequences between monitoring angle and sensor signals are not maintained in the event of an error, a TDC stop is initiated or the press is stopped immediately.
• Press force monitoring
  The press force characteristic can be monitored either in a measuring window or continuously for minimum/maximum force. This software module can also evaluate sum and differential forces for effective press protection against overload.

Example applications
Because of the different types and classes of machine in operation, it is always necessary to customize the user interface, machine control, and operating modes, etc. The machine manufacturer makes these modifications during commissioning of the plant. To keep engineering costs as low as possible, we provide you with tested example PLC programs. These S7 user programs have been developed in statement list format (STL) for typical press operating modes, such as single stroke, permanent stroke or set-up operations, and can be extended and modified easily using STEP 7. Furthermore, we offer sample operator screen forms, with Press2000S for OP27, with Press2000M7 for OP37. Using the ProTool design tool, these can easily be modified and supplemented to generate customized user interfaces. When using other OP devices, our example applications help you to get started as quickly as possible.