Swing Ear Punch for Box Bending with Return Flanges
January 10, 2023
Swing Ear Punch for Box and Return Flange Bending
Bending boxes, pans and enclosed sheet metal components with inward return flanges can create a difficult tooling problem.
After the return flanges are formed, the opening of the finished part may become narrower than the working width of a conventional solid press brake punch. Although the bending operation can be completed, the formed workpiece may become trapped around the upper tool and cannot be removed normally.
A Swing Ear Punch provides an effective tooling solution for this type of application.
How the Swing Ear Structure Works
Unlike a conventional solid punch, the upper section of a swing ear punch incorporates movable left and right ear sections.
During bending, these sections provide the required working profile for forming the sheet metal part. After the bending operation, the movable ears can swing or move away from their normal working position, reducing the effective removal envelope of the upper punch.
This additional clearance allows the finished box or pan to be released from the tooling even when its inward return flanges create an opening smaller than the normal punch profile.
This type of tooling is also described in the press brake tooling industry using terms such as hinged ear punch or hinged ear sections. It should not be confused with a hinge forming tool, which is designed to form hinge features in sheet metal.
Designed for Boxes, Pans and Enclosed Profiles
Swing ear tooling is particularly useful when conventional fixed punches cannot provide sufficient clearance for part removal.
Typical applications include:
- Sheet metal boxes and pans
- Electrical cabinets and enclosures
- Machine covers and equipment housings
- Control cabinets
- Components with inward return flanges
- Deep box-shaped sheet metal parts
- Partially enclosed profiles
- Parts that become trapped on conventional solid punches after the final bend
The tooling makes it possible to consider not only how the part will be bent, but also how the completed part will be removed from the press brake tooling.
Custom Swing Ear Punch Designs
The images shown here demonstrate several different sizes and profiles of swing ear tooling manufactured by WYS Machinery.
There is no single standard geometry for every application. The tooling structure can be developed according to the finished sheet metal component and the required bending sequence.
Depending on the application, we can customize:
- Punch height and width
- Swing ear dimensions
- Working profile and bending geometry
- Clearance and release movement
- Tooling length
- Segmented or special-length configurations
- Mounting configuration
- Press brake compatibility
Different sizes of swing ear punches can therefore be designed for different box depths, flange dimensions and workpiece geometries.
Tooling Designed Around the Finished Workpiece
For special return-flange applications, simply knowing the required bending angle is not enough.
The tooling designer must also consider the internal box dimensions, return flange length, material thickness, bending sequence and final opening of the workpiece.
WYS Machinery can develop a custom swing ear press brake tooling solution based on the customer's finished-part drawing and bending requirements.
By incorporating workpiece release into the tooling design, the swing ear mechanism makes it possible to produce box-shaped and partially enclosed components that would otherwise be difficult—or impossible—to remove from a conventional fixed press brake punch.
