Simple Solutions That Work! Issue 14

32 Contact: ROB EWING [email protected] A complete 7AA solution reduces setup time through an easy installation process and also preconfigured teach screens. Adapter flanges on the arm allow for simple vertical adjustments to shorten or extend the arm to match the installed holding furnace and shot end. The robot teach screens allow any operator to easily adjust the filling sequence, transfer speed, transfer level and pouring profile into the shot sleeve without prior knowledge of robot programming. The combination of easy mechanical installation and simple program setup results in a ladle arm that is up and running quickly and efficiently. A teach screen that is simple and easy to understand encourages operators to optimize and dial in the pouring sequence using the tool to its full potential. An optimized ladle program reduces cycle time and allows the operator to obtain a gentle and perfected pour for increased part consistency. Once optimized, programs should be saved in memory, password protected and recalled later for any time that part is produced on that machine. Another advantage of the 7AA that increases part consistency is in the mechanics of the arm itself. A shaft- driven mechanism reduces backlash in the system ensuring the same fill angle of the ladle cup each cycle. When mounted to a robot, repeatable positioning of the ladle cup within +/- 0.14 mm is possible. To control the depth of the ladle cup during fill, a non-contact laser can monitor the metal level. The sensor should mount next to the furnace, removing the possibility of critical wiring being damaged during operation. The sensor should be calibrated from the supplier prior to installation to accurately read the surface molten aluminum bath, as an inaccurate reading leads to varying fill weights. However, by maintaining a consistent draw depth and fill angle fill weight accuracy of +/- 1% are possible. Most 7AA’s use a traditional pour shaft and bearing arrangement. A fully sealed high temperature bearing design can be submersed in the metal without damage to the arm. In the event of a sensor or program failure and subsequent dunking of the ladle cup, the sealed bearings ensures that the pour shaft and arm remain free of molten metal, increasing uptime. As a final advantage, a 7AA achieves a cleaner metal delivery to the shot sleeve than other methods of automated ladling. The preconfigured robot program can include a skimming feature to remove dross from the surface of Figure 2: Example Ladle Fill Setup Screen the bath before metal is allowed to fill the cup. This reduces the amount of inclusions that can occur in the final part. The ability to input a custom robot tool center point (TCP) is useful to place at the pour spout of any custom ladle cup used. This means that during transfer the robot can keep the cup perfectly level in pitch, yaw and roll so that the surface is not disturbed, reducing the chance for oxygen to interact with the metal. Using a TCP that is customizable to the pour spout, the 7AA is also able to pour into the shot sleeve in the same fashion as one would fill a beer glass. This laminar flow during pour again reduces the chances of oxidation in the melt. With the reach of the 7AA extension, the robot can position the cup to pour straight down the shot sleeve. This removes the splashing action that occurs against the inner wall of the shot sleeve that would typically allow oxygen to become entrapped. Figure 3: Example of fully sealed pour shaft Figure 4: Example approach paths to the pour hole on the shot sleeve, 7AA vs. typical path Automating the ladle process is one of the quickest ROI available in die casting. Utilizing a 7th Axis Arm on the end of a robot, when coupled with an easy to use mechanical installation and quick program setup, can enable more consistent parts, cleaner metal and higher uptimes over traditional linkage design robots or 6 axis solutions with a fixed ladle cup.