Bending sheet metal brackets

Sunday, July 6th, 2014

Here’s a nice example of using custom made CNC bend tooling to form bends that would be too small with normal air bending V dies.

Sheet metal bracket blanks produced by CNC punching

This small bracket has a couple of features that are of interest before we even consider the processes needed to bend it up. A bracket like this can be made with press tooling but the volumes need to be high enough to justify the initial cost of the hard tooling. The volumes and repeat period for these brackets perfectly suited CNC punching and CNC bending. When considering CNC punching these brackets we were able to use a standard circle and square from our Trumpf punch press tool library, so at no cost to our customer. The U shaped feature is created using 2 hits with a L shaped tool, this helps to make a stronger die and was suggested by the tooling department at Trumpf who we are always happy to work closely with. The complete outer profile for the blank was punched down one die on the CNC punch press allowing us to produce a clean part with 4 corner rads and very quickly.

Double bend CNC press brake tooling

Once we have a CNC punched blank part we can form in 3 small bends that are too close to each other for us to bend with normal standard library tooling. The distance between each bend was only a couple of mm so had to be formed in and coined up in one go. Again we worked with Trumpf’s tooling department giving them accurate CAD data of the final part wanted and free issued them with a number of blanks from the correct material and gauge so that they could experiment and fine tune the final results from the press brake tooling before hardening it.

The tool was supplied from Trumpf with all the tool data needed to load it straight onto our 7036 press brake and register it’s form within the tool library ready for CNC programming.

As an aside you can see the rear back stops with the corner ears cut out. This is a feature on both of the back stops that allows us to fit in tricky shapes at time when a plain flat back stop wouldn’t be possible. You can also see a red cross shape, this is the red light from the laser guard hitting the side of the tool while we set up the machine. The laser guards allow us to get in much closer to the machine than older light guards allowing a quicker operation of the machine and a more comfortable position for the operator to be in, which is so important on longer runs of parts.

Standard CNC bending tooling

Once the sheet metal punched blanks had the triple form feature pressed in and another standard 90 degree bend on the Trumpf 7036 we had to transfer them to one of our Guifil CNC press brakes for the final tight bend. We have some press brake tooling that we had specially machined back for another job in the past and this was perfect for forming this tight double bend. If you click on the image you will see how thin the end of the tooling is but very little tonnage is needed to form over the thin gauge zintec so it was quite acceptable. You can also see that we separated the 2 bottom V blocks to produce a gap that the small U shaped tag would protrude into while being bent up. This was necessary else the tag would have been bent as well. It’s amazing how many different machines, tools and techniques are needed to manufacture what looks like a simple sheet metal bracket.

Finished sheet metal brackets

Well here we are with the finished brackets. They will be used to help support LED light fittings into a ceiling grid on a refit program on a number of sites.

If you have a sheet metal bracket that needs manufacturing and you are not exactly sure what can be achieved with sheet metal please give us a call or send your initial design ideas and we will be happy to help you refine your designs and produce a quote for you.