Page 33 - MetalForming March 2015

Figs. 6-7—Segmented knockout tools punch larger knockouts with less press tonnage than when using smaller tools.
press, use a segmented knockout tool (Figs. 6-7). These knockouts won’t be as ‘pretty’ as those formed by a standard knockout tool, but they do the job in many applications. These tools position knockout tabs at specific locations to facilitate slug removal.
A variation of the segmented knock- out is the arch-bridge lance and form tool, with each edge of the arch cham- fered to help overlap the hits and min- imize distortion.
Employing either tool for larger knockouts uses less tonnage than stan- dard tools on smaller knockouts, thus reducing machine wear. Another knockout technique for minimizing machine wear: use of down-forming. It produces a larger footprint without requiring increased press tonnage. In contrast, up-forming requires a spring stripper and additional force.
Rollerball and Straightline Deburr Tools Eliminate Secondary Operations
The rollerball deburr tool is designed for thick-turret and Trumpf-
Fig. 8—Always a problem, burrs on parts can be removed using a rollerball tool (shown) or straightline deburring tool.
style presses. This tool, operating in the x and y axes of the press with the ram down, pushes the burr away and creates a radius on the side of the part (Fig. 8). Using a special ball in the upper and lower part of the tool, all part contours can be processed, including small corners.
The straightline deburr tool deburrs in a straight line as well as through tight corners, and is used in an auto index station or as two tools set at 90- deg. angles to each other. It utilizes a raised area on the die, angled at 20 deg., and coins the burr back into the material’s fracture area. The 20-deg. angle helps prevent sideways move- ment of the material or parts. While not material-thickness-specific, the straightline deburr tool is parting-tool- specific, and should be designed for use with a specific-width parting tool when immediately deburring adjacent parts. It also can be used to deburr a single side or the interior of a rectan- gular opening.
Both straightline and rollerball deburr tools are good tooling invest- ments because they eliminate time- consuming and expensive secondary burr-removing operations. MF
Article provided by Mate Precision Tooling, Anoka, MN; www.mate.com
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