Special tool for making Zs in one stroke, this is the latest special tool custom made by METALMAQ for a customer in France who has three press brakes at their facilities.
THE DIFFICULTY OF THE PART
Our customer manufactures parts for electrical installations and wanted to streamline the production of a product in high demand. Instead of bending the part in two steps and turning it over (between bends), he wanted to do it in one go without having to turn the part over.
The part in question is a 1.5 m/m L-shaped stainless steel sheet with a total length of 2,500 m/m.
The customer has a 130 tonne, 3 m AMADA press brake (specifically the AMADA HFT 130-3 model), with Promecam type top and bottom clamping (this type of clamping is also known as the European system, the Amada system or the Mebusa system) and is one of the most widely used worldwide.
SOLUTION ADOPTED BY METALMAQ
Our Technical Office designed the special tool and, at the customer’s request, made it in 3 sections of 835 m/m (a total length of 2,505 m/m), as this facilitates the work of installing it in the press brake as it is easier to handle than a whole section measuring 2,505 m/m.
What is really important in tools of this type is to calculate the force (in tonnage) that the press brake will need to perform this multiple bending. The tool will be working with 1.5 m/m thick stainless steel sheet (with a resistance of 70-72 Kg/mm2). According to our calculations, to make the two bends in one go we will need a tonnage of 35 tons per metre. As the customer wants to bend 2.5 metres; 35 Ton x 2.5 metres; we will need a total of 87.5 Tons. We will have no problem in doing this job as the press brake has 130 Tons.
This type of calculation is very important when manufacturing special tools that have to make several bends at the same time, as the tonnage requirement increases exponentially and the calculations must be made before starting the tool study.
The tool consists of the punch (upper part of the tool) and the die (lower part of the tool).
The attached pictures show the shape of the part once the pressing is done. In tools of this type, it is necessary to make a certain inclination in the measurements, as in multiple bends the sheet metal usually has quite a lot of elastic return, and therefore the tool must be compensated with somewhat tighter angles. Apart from our experience, the extra inclination is determined by testing the prototypes that we usually make at the beginning of the project and with the sheet metal samples sent to us by our customer.
The pictures above show the tool installed on our test press brake. This is one of the last stages of the project, when the special tool made to order is checked and approved.
The tool is made of 42CrMo4 steel, induction hardened in the working areas and ground, thus guaranteeing optimal durability over time.
RESULT
The pictures below show the finished part. They also show the slightly larger radii.
Special tools with multiple bends usually leave a slightly larger radius than normal bends made with the press brake (bend by bend), and this must be taken into account when designing the parts.
In view of the attached video, the result is excellent, i.e. both bends are made at the same time with optimal results, thereby increasing the productivity of our customer.
