Machines with a true profile: drive, control and assembly technology from a single source

Machines with a true profile: drive, control and assembly technology from a single source
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July 2016

 

Machines built by NuLine, a U.S.-based company, produce large plastic bags used to line transportation containers. Rexroth technology helped NuLine create a high-performance, visually-appealing next generation.

In global logistics there are virtually an unlimited number of different types of packages. One category among such units is called intermediate bulk containers – IBC. When transporting liquids such as cooking oil, IBC manufacturers line their containers with plastic bags that may hold as much as 1,135 liters. Producing these bags requires special machines that work with extreme precision. One of the few manufacturers of such systems in North America is NuLine Manufacturing, located in Denver, Colorado. When developing its latest generation of machines, the company wanted to achieve not only a compact and efficient control concept, but also an attractive design for the machines. The modular system was to be such that it could be engineered, assembled and tested in Colorado and then disassembled for shipping.

One control for every need

Inside the machine, twelve of the twenty axes are equipped with servo motors and linear modules made by Rexroth. All twenty motors are moved by IndraDrive Cs compact drives. “Working with NuLine, we determined that virtually everything on this machine, all the servo drives, the unwind control, the HMI, the fitment feeds, could be controlled by the IndraMotion MLC PLC,” explained Alex Runge, Vice President at AAP Automation – the Rexroth distribution partner working with NuLine on the new machine. The MLC lets NuLine move plastic webs through the machine both reliably and precisely – even though the polyethylene material is extremely malleable and stretchy. The controls have sufficient capacity to support both the large number of axes and the extensive I/O network. Used as the control hardware in the machine is the IndraControl L platform, made by Rexroth and which can be scaled to suit. It offers many input and output interfaces and supports a variety of bus architectures, including Sercos III and Profibus. NuLine selected IndraDrive Cs as the drive platform due to its compactness and efficiency. “They’re reliable, they work well with third-party systems, and their compact size helped us save space on the control cabinet’s footprint,” Runge explained. In addition, the IndraDrive Cs can support motors built by Rexroth and by outside vendors, as well. A further advantage of the Cs drive is the option for regenerative use via an intermediate circuit coupling. “This Rexroth technology is becoming more widely adopted for multiple reasons,” explains Runge. “It’s energy-efficient, plus it vastly reduces the amount of cooling needed for the control cabinet, since you’re not generating heat by bleeding off energy through resistors.“It also keeps costs down by eliminating components like resistors and circuit breakers. From a controller perspective, this was the most integrated machine NuLine has ever built, with one controller handling the whole machine,” Runge boasted.

The IndraMotion MLC allows NuLine to move plastic tracks reliably and accurately through the machine.

The IndraMotion MLC allows NuLine to move plastic tracks reliably and accurately through the machine.

 
In terms of control hardware, the machine uses the IndraControl L, which supports many input and output interfaces.

In terms of control hardware, the machine uses the IndraControl L, which supports many input and output interfaces.

Appealing esthetics

“Although there are components and technology approaches in this machine that we’ve utilized in past bag-forming machines, this is really a new design from the ground up, especially in the use of Rexroth aluminum profiles,” explains Greg Herivel, President of NuLine and the machine’s chief designer. According to him, the decision was based on both functional and esthetic reasons. In the past NuLine made up the frames for its machines from steel. All the components were either welded or bolted together. This consumed many hours of labor and made it difficult to make modifications of the machine’s design at short notice. “The Rexroth framing gave us the flexibility to make changes that we never had before,” says Herivel. “If we wanted to change how we mounted a subassembly, we just unbolt it from one location and bolt it on in the new location.” NuLine ordered a large variety of different aluminum profiles from the very start and set up an extra assembly station in its plant. This made it possible for the company to modify the profiles just as quickly as they were needed in assembly operations. Herivel is also very satisfied with the appearance of the profiles: “I was certain that if we could go forward with a design that incorporated the framing from the ground up, it’s going to give a more modern, fluid looking machine and a better appearance.”

NuLine is more than satisfied with the performance of all the Rexroth components. Herivel is quite sure that the modular system using aluminum sections will open the door to many further uses. “I think this machine demonstrates that an all-aluminum profile machine, utilizing technology like Rexroth’s structural framing, provides a solution that combines functionality, ease of machine assembly and good aesthetics in one package.”