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Blow Molding

Blow Molding Control Solutions, Upgrades and Retrofits
Utilizing Allen-Bradley Solutions

Rockwell Automation Solution Provider

PDF - Industrial Control Solutions-Blow Molding

JVH Engineering provides process control for blow molding applications by using off the shelf Allen-Bradley SLC-500 components including the 1746-BLM parison control blow molding module. The BLM module is an intelligent module that fits into a standard SLC-500 chassis and communicates to the main processor via the backplane. Since the BLM is a “smart” module, all high speed closed loop process control and advanced mathematics are performed within the module without slowing down other important PLC and communications tasks. The system can control up to four machine axes simultaneously which allows for two accumulator machine heads or four heads of a continuous extrusion machine. The 1746-BLM module performs its servo control tasks independently but it receives its configuration and run-time information from the SLC-500 processor. All of this is taken care of independently of the operator interface.

The Allen-Bradley blow molding control system offers an interpolation feature and a maximum of 256 set-points for parison profiling. Whether using 10 set-points or 256 set-points are entered, the system automatically calculates and interpolates the profile. With an update rate of 100 microseconds and up to 256 set-points, this system has superior profile resolution and more accurate blow molding performance that other blow molding control systems in the industry. Other features include the ease of changing profile parameters. For example, the profile can be offset to add or subtract part weight without changing the profile shape. It can also be scaled to change the shape but not the weight of your part. Thus, the automatic interpolation and other simple-to-use features increase user productivity and more accurate profiling in less time.

The 1746-BLM module is designed to support a variety of plastic machine applications including accumulator machines, reciprocating screw machines, and continuous extrusion machines. The modularity of the Allen-Bradley architecture allows for multiple blow molding modules to be used for larger machines.

Accumulator Machines
This control system controls parison wall thickness on accumulator machines by following a set-point profile of wall thickness versus accumulator ram position. In this configuration, the module is capable of controlling up to two blow molding heads. For each head, one analog I/O channel is used for mandrel position control, while another is used for accumulator ram velocity control. Optionally, the module may simply monitor the position of the ram only. The mandrel position and accumulator ram velocity are both normally specified as a function of the accumulator ram position. Since the module supports a mixture of time-based and position-based modes, one may also specify accumulator position as a function of time.

Continuous Extrusion Machines
This system controls parison wall thickness on continuous extrusion machines by following a set-point profile or wall thickness versus time. We can control up to four blow molding heads in each module. Four analog I/O channels are used for mandrel position control. Mandrel control is a function of the elapsed time since the last synchronization signal indicating start of parison drop.

Reciprocating Screw Machines
Reciprocating screw machines have multiple heads and a single screw/accumulator. Control of the screw position is performed by the SLC processor while the BLM module may be used to monitor the screw position in either of two ways on this type of machine – with analog input on the BLM or with separate high speed analog module. In either case, analog channels on the BLM module can be used for control of parison tooling or for monitoring / control of reciprocating screw motion. Since the system supports a mixture of time-based and position-based modes, one may also specify screw position as a function of time.

JVH Engineering has developed a Human Machine Interface (HMI) utilizing Rockwell Software’s RSView 32 graphical operator interface software along with Microsoft Windows Visual Basic. This HMI allows for complete control interface to your machine with intuitive screens for parameter adjustments, parison profile monitoring and adjustment with up to 256 set-points, and diagnostic screens for trouble-shooting and maintaining your machine. This software is licensed by JVH Engineering and is copy write protected.


Rockwell Automation Solution Provider | Industrial Automation

JVH Engineering • 3040 Ivanrest Ave., Grandville, Michigan 49418 • Phone (616) 531-9861 • Fax (616) 531-7763
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