Measuring and testing – Specimen stress or strain – or testing by stress or strain... – By loading of specimen
Patent
1988-01-21
1989-04-11
Levy, Stewart J.
Measuring and testing
Specimen stress or strain, or testing by stress or strain...
By loading of specimen
73841, G01N 324
Patent
active
048194883
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
1. Field of the Invention
The invention relates to an apparatus testing resistance to cleavage of cardboard tubes, in particular for tubes intended to be used as winding formers used, for example, in the printing industry.
2. Description of Background and Material Information
It is known to wind sheets of paper on mandrels comprised of cardboard tubes. Bobbins of this kind are handled by machines adapted to grasp from the inside the ends of tubes serving as winding formers.
Likewise, the bobbins, particularly in the printing industry, are positioned on unwinding machines or rotating machines in order to unwind the bobbins for printing the sheet of paper and/or cutting it and/or folding it, etc. To this end, machines used for holding the bobbins comprise two arms which are introduced into the two ends of the cardboard tube used as a winding former and which keys the latter by means of expansion heads provided with jaws capable of projecting towards the outside. The above-mentioned expansion heads are mounted free to rotate, so that the bobbin can freely turn as it unwinds.
It is clear that the winding formers are submitted to very heavy stress, caused by the weight of the bobbin, the speed and duration of its unwinding, to the pressure exerted by the expansion heads and, sometimes, to the braking stresses of the expansion heads which are blocked in rotation, in case, for example, of an emergency stop when the bobbin has a high kinetic energy.
The features of the cardboard tubes selected to be used as a winding former are therefore important and, up to now, the material used, the thickness of the tubes and other manufacturing parameters are chosen in an empirical manner with as the only resistance test, the actual operating test, by starting with the empirical observation that a tube resisting beyond a given time, as a function of the weight of the bobbin, should resist the entire time it is used.
It has been observed that cardboard tubes being used as winding formers are destroyed by cleavage or unflattening of the material at the end of a length of time which is a function of the above-mentioned stresses and more particularly a function of the weight of the bobbin. One can in effect observe that as the bobbin rotates (generally very quickly), each section of the mandrel, which turns with said bobbin, is alternately submitted to very different forces, the crushing caused by the weight occurring only when said section is turned upward.
There are already machines for testing the resistance of tubes to compression, to bending, to hardness (by ballbearings for example). These tests are used but are very inadequate when it is a matter of determining the features of a tube intended to be used, in particular, as a winding former.
This is why the inventor imagined an apparatus intended to test the resistance to the cleavage of cardboard tubes which are, to this end, cut in the form of samples or test pieces.
SUMMARY OF THE INVENTION
The machine according to the invention is remarkable in that it comprises a keying mandrel which is mounted free to rotate, at least one sleeve for each different outer diameter of the test pieces and whose inner diameter is close and at least equal to said outer diameter of the test pieces, so that for each test piece, there is at least one corresponding sleeve intended to house said test piece, the keying mandrel being adapted to receive, while keying it, each test piece surrounded by a corresponding sleeve, while a drive belt is provided in order to be stretched between said sleeve and a drive device, in order to rotatingly drive the assembly comprised of the keying mandrel, a test piece and a sleeve.
The machine according to the invention reconstitutes the stresses to which are submitted, in particular, the winding formers, the sleeves materially representing the bobbins whose weight is simulated by the tension of the drive belt.
Preferably, the inner diameter of a sleeve is very slightly higher than the outer diameter of the corresponding test pieces
REFERENCES:
patent: 2650493 (1953-09-01), Bowen, Jr. et al.
patent: 2657573 (1953-11-01), Castricum
patent: 3234783 (1966-02-01), Hanson
patent: 3797304 (1974-03-01), Klinger
patent: 3934464 (1976-01-01), McCauley
Levy Stewart J.
Lhomme S.A.
Raevis Robert R.
LandOfFree
Apparatus for testing the resistance to cleavage of cardboard tu does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Apparatus for testing the resistance to cleavage of cardboard tu, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Apparatus for testing the resistance to cleavage of cardboard tu will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-658774