Oxford Automotive (Canton, MS), a Tier 1 automotive supplier, employs a robotic cell containing a number of six-axis industrial robots. The robots use tool changers from ATI Industrial Automation (Apex, NC) and a DeviceNet network for tooling control. In the cell, the robots complete a variety of material handling and welding operations, performing multiple tool changes during each cycle. Each robotic end effector has multiple I/O devices and sensors.
After implementation, engineers found that throughput was falling short because standard DeviceNet modules on the tooling were taking too long to come online during tool changes. Specifically, the Oxford plant was experiencing delays of up to 8 seconds per tool change during a multichange cycle. Due to the cycle frequency, this series of delays added significant time to the process, to the point of being unacceptable.
To address the problem ATI installed an InstaTool system, including an InstaTool module on the tool-side portion of the tool-changing mechanism to speed up information exchange between the tool and the DeviceNet controller.
The usual means of obtaining DeviceNet I/O from robotic tooling is to pass DeviceNet signals through the tool changer to the nodes on the tooling. With this method, each device on the tooling is a node on the host network and is connected and disconnected with each tool-change cycle. Using standard DeviceNet technology incurs a substantial delay before tool identification can be achieved, adding delays to the cycle.
With ATI InstaTool technology, the host DeviceNet signals travel no further than the tool changer master-the part of the tool changer attached to the robotic arm-which is connected to the network at all times. The I/O information is processed by commercially available DeviceNet I/O blocks located on the robotic arm. When a tool is attached, these DeviceNet I/O blocks are connected via standard DeviceNet wiring to the ATI InstaTool module on the tool side of the tool changer. The tool communicates the I/O to the tool changer master with a non-DeviceNet industrial communications protocol. The DeviceNet block on the tool changer master then passes the information on to the DeviceNet controller. Because the DeviceNet controller accesses tooling I/O as if it were part of the tool changer master DeviceNet block, or node, connection delays are greatly reduced.
With the InstaTool system in place, tooling I/O is available to the host network in less than 1 second. No additional time than is required to complete the tool coupling operation. As a result, the tool change delay has been completely eliminated. The robot moves, with tool attached, immediately after the lock operation is completed. There has been no observed latency on any of the control signals or sensor inputs, and Oxford has experienced a dramatic improvement in efficiency and productivity using InstaTool.
For more information on tool changing, call 919-772-0115 or visit www.ati-ia.com.
