METAL PRESS BRAKE BENDING AUTOMATION
METAL PRESS BRAKE BENDING AUTOMATION
Automation of bending is the subject dedicated to the manufacturers of press brakes.
There was the request where the customer want to bend steel with 25 mm thickness. Nothing special and it is possible to offer the quotation but also is necessary to justify could the machine will be able to provide the high tonnage at one area without any damage and deflection. And moreover it was standard Promecam system which is normally only for 100 t/m and the reason to change intermediates for thicker one. All of these things are not standard but not really complicated to deal with and moreover we checked the possibility to supply adapters to move to Trumpf-Wila because for this system and width 20 mm tools 200 t/m could be possible.
Ok, but what is here about automation? Customer wants to buy press brake tools to start new production. But what is the weight of part? Mainly it was quite small width but more than 35 kg. So how you will deal with it? It is possible to make the project and to calculate everything but how to handle the part of big weight if it will be real typical production with quantities each day? And funny story that customer didn't think about it too. And this means that all our stuff could be completely useless if the customer can't handle the part in production. No, he can organize the handling with two workers or workshop light crane but the constant manual handling doesn't lead to the normal production.
So the first reason is not to think about the tools but to know about automation. For several bends and new press brake it could be the following frontal support which follow the part during the bending. But to make the full handling it is necessary to think about automatic or semiautomatic system to move the part or robotic solution.
Yes, the first field of automation is not the repeatable massive job but the heavy parts where manual handling is quite hard or impossible. Moreover the market offers also the solutions for existing press brakes to equip them with automatic system.
The other story is massive production. Work of press brake operator is not the easy one. He need all the hours to stay at the front of the machine and to make the moving of pieces one by one. If the job really repeatable, robot could be really great solutions to increase the productivity and moreover to enter the mode of 24 hours working shift. Moreover there are different developments to change the jobs, change the press brake tools, change the pallet for loading and unloading of parts etc. It is useful to know that the robot is also very flexible investment if you made the right choice - tomorrow you can move it to other applications and install welding system for example. Robotic sheet metal bending not so massive product like welding cells for example but there are a lot of reasons to run with robots. And it is also the side of the investment to new digital technologies, modern factory and the latest innovations at the field.
It is interesting also to see that some manufacturers develops also robotic innovations to change the press brake tools with second robot on fly. With one robot it is quite problematic because the necessary to change the gripper. But if you are looking for really fast production and change of working cycles there are possible to supply also special tool racks together with robot or other manipulator to prepare on the press brake new tools for the new job.
It is interesting to know that automatic solution could be also not the stand-alone bending cell but the connection to other systems, for example transfer the parts from punching or to and from other areas. There are a lot of fantasies and projects which should be true - several robots for long parts, gantry systems or rails for robots to move it out of press brake area if necessary to work by operator again, small work of punching station, fastening operations etc.
Testing Press brake tooling
Press brake bending is the theory for all press brake tools manufacturers. When the customer asks for tonnage, springback, tolerance, angle - all what is possible to provide is the main theory. Yes, it is based on some experience, formulas, ideas and calculations but when the tool was not tested with your steel - there are only theoretical parameters.
Moreover everybody who works in production is informed that even the same trademark of material from different batches could lead to different results in deformation.
How theory becomes practice. There is no magic - nobody of press brake tools manufacturers has in workshop press brake even for 100 tons to test all parts. So normally any test goes to the small length of part to test with compact press brake. Moreover if customer asks strict tolerances probably everybody ask for bigger gap - it is hard to take all costs for mistakes and to guarantee something extremely precise and special. And there is other black spot - even if you can test tool for 100 mm it doesn't guarantee that results will be the same in two meters - there are longitudinal relations as well. But anyway if the tooling should be shipped and the shape is special, it is impossible to ship the theoretical shape and non-tested production result because the manufacturer should have some obligations about the tool he developed. That is why the question in-shop testing is necessary and should be solved before shipment.
How to test if possible to test? There are two main available small costs practices: laser cutting sections with welding or plastic based dimensional printing. Plastic based printing is completely new solution with incredible advantage - just necessary to have 3d printer to make the prototype. But there is also one big disadvantage - plastic is not the metal and this means strength of plastic is enough to test special tools for thin material applications. But anyway plastic prototypes have the good future for development - 3d metal printing is the nearly future. Moreover to add more strength to the tool it is made not only with plastic 3d printing but with some internal metal inserts around the working zone to prevent some big deformation. Anyway it is not the working solution but the tool for tests.
Laser cutting together with the welding - traditional testing process to make small section of special tool. Disadvantage of the process is the access to laser cutting machine but the advantage that you will have real metal not hardened tool with the necessary shape to make the test bend. Is there the future for development? Hard to say but replacing of laser cutting to waterjet can give the possibility to cut solid sections about 50 mm or more with greatest precision. It is also important that the costs for preparation of such shape are very low to make just several cuts in one sheet.
What is the final for the test? Normally the bend quality and geometry which is acceptable by the customer to start the manufacture of normal bending tool with proper material and hardening. Or the feedback that allows to make modification. The reason of testing and testing tool prototypes is very important - nobody wants to deal with the modification of prepared and hardened tooling after the sale. And any possibilities should be used to reduce to the minimum of any risks. So the test prototype is the way to control the deformation to remake the theory into the real bend.
Anyway every repeatable process has the solution to realize but based on the limits for part and the tool. It is the question of experience and the field knowledge. The main point is usually only one - customer has the real and reasonable requirements and accept the calculations of special tools. All other should be the subject of study. And there is no the black point, even with thick material is possible to make the modulation of forces and stress to have the theory realistic. It is not usual procedure but helps to terminate the black spots.