R&B Plastics Machinery LLC of Saline, Mich., has integrated the motion controls for its blow molding machines, including parison control, into off-the-shelf Siemens programmable logic controllers.
R&B had been using closed-loop hydraulic motions with dedicated-motion control cards, which Atlanta-based Siemens Energy and Automation Inc. said are expensive and somewhat difficult to co¼ordinate with programming.
A standard Siemens S-7 PLC controls the motion control function, which handles the positioning of hydraulically actuated components. For example, one R&B machine has nine axes of servohydraulics —three for parison control and six for motion control. The machine has two shuttles, two molds and two blow pins.
The first of the motions that R&D tried to manage through the plc was the parison. Normally, blow molding machines are controlled by a machine controller with a separate, dedicated independent parison programming unit with a dedicated-motion control card; or by personal-computer-based automation using proprietary code to handle motion control.
But R&B wanted to integrate parison programming in the main machine controller, which was possible using the PLC.
Next, R&B integrated the rest of the servohydraulic axes into the PLC. Another function the PLC runs is camming of the blow pins with the carriages.
The PLC also is managing more than 30 zones of heat control from the hopper to the extruders, and through to the parison head, the company said.
Tel. 734-429-9421, fax 734-429-1805.