The Magnabend Slotted Clampbar
The slotted clampbar is one of a number of important innovations developed for the Magnabend sheetmetal folding machine.
The sections between the slots are the equivalent of the adjustable "fingers" of a conventional pan-brake machine, but with the Magnabend clampbar they never need to be adjusted as the design allows for all sizes!
This innovation resulted from 3 important observations:-
Firstly it was noticed that it is not necessary to have a continuous bending edge because bends will carry across reasonable gaps left between the fingers with no noticeable effect on the bend provided that the fingers are well aligned, and they always are well aligned on the slotted clampbar because it has fixed "fingers".
Secondly it was realised that by careful arrangement of
slots it is possible to provide for an infintely graded set of sizes up
to almost the full length of the clampbar.
Thirdly it was noted that finding the optimum positions
the slots is NOT a trivial problem.
But the interesting problem is to find the minimum number of slots which will provide for all sizes.
There seemed to be no analytic solution to this problem and that fact turned out to be of considerable intererst to 2 mathematicians at the University of Tasmania.!
But the problem was solved by engineers at Magnetic
Engineering (mainly Mr Geoff Fenton) who came up with a computer
program employing the "Monte Carlo Method" to find the best set of slot
positions. (See the table below).
Drawing of a slotted clampbar to suit the model 1000E (1 metre) Magnabend :
Slot Positions for Magnabend Models:Note: The positions shown in the table below are measured from the left end of the clampbar and are to the slot centres .
Units are in millimetres.
FORMING TRAYS USING THE SLOTTED CLAMPBARThe Slotted Clampbar, when supplied, is ideal for making shallow trays and pans quickly and accurately.
The advantages of the slotted clampbar over the set of short clampbars for making trays are that the bending edge is automatically aligned to the rest of the machine, and the clampbar automatically lifts to facilitate the insertion or removal of the workpiece. Never-the-less, the short clampbars can be used to form trays of unlimited depth, and of course, are better for making complex shapes.
In use, the slots are equivalent to gaps left between the fingers of a conventional box & pan folding machine. The width of the slots is such that any two slots will fit trays over a size range of 10 mm, and the number and locations of the slots are such that for all sizes of tray, there can always be found two slots that will fit it. (The shortest and longest tray sizes the slotted clampbar will accommodate are listed under SPECIFICATIONS.)
To fold up a shallow tray:
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