We have spoken, in the precedent paragraphs, about the technical and quality advantages derived from the use of our programs.
But these are not the only advantages.
In the point 9.2.1, we have indicated that the weigth of the rope may be, in the some case, reduced, in spite of fullfilling completely the international standards from all the points of view: Diameter, cross section, weigthper length unit, breaking load...
In the factory where we was Thecnical director, we have seen this problem, and we have studied that would happen by adopting our method.
The study has been made in November 1989, and updated to 2009.
The summary is:
|Total production considered||4264,70||t/year|
|Total saving in wire||210,01||t/year|
|Cost of the saved wire|
|Equivalence U$$, 1990||111.290,00||US$/year|
|Industrial Prices Variation In Spain 1990/2008, %||173.06||%|
|Equivalence US$, 2008||195.165,00||US$/year|
In the appendix can be seen de differnet calculations made for this consideration.See article
ANALYSIS OF THE BREAKAGE OF TWO WIRE ROPES
This article studies two actual cases of ropes that have produced during their use the apparition of severe faults that would produced the breakage of both. By this reason they has been returned to the two different makers.
Using the calculation methods developed in the programs, we have seen the origin of the defects, in the penetration or negative clearances between wires and strands.
The drawing of the same using AUTOCAD has given the possibility of to measure the faults, and of reproducing the apparition of the faults.
They are presented , and drawn,ssollutions for this problem.
In the second rope ,they have been produced numerous breakage of the wires in the outer layer.
The study of the stresses produced during the flexion in the drums or pulleys of the drag , has shown that they have surpassed widely the elastic limit of strength in the wires. They are also proposed solutions.
COMPUTER PROGRAMS FOR THE DESING OF STEELWIRE ROPES
This system which is extremley accurate, has been developed for calculating the exact dimensions and specifications of steel wire ropes. The principles of the calculations, the contents of the programs and their possibilities are given in a logical order.
Examples of printouts will show the easily read result, with one illustration of a Warrington-Seale strand .
THE FATIGUE STRENGTH OF STEEL WIRE ROPES - PART I
One of the factors that has the greatest influence in the live of a rope, on his effective life, is the fatigue strength that it must support.
This effective life is determined byt the succession of alternating stresses. These stresses are defined not only by intensity, by amplitude of oscilations that such stresses involve, but also by frecuency.
FLECTION STRESSES IN A STEEL WIRE ROPE - PART II
Part I of this series of articles on "The fatigue strength of steel wire ropes", published in the October 1994 issue of Wire Industry, gave a study of the geometry of a rope.
This knowledge is of primary importance in calculating the alternating tensions and hence the stresses ina rope, which this article atemps to provide.
THE FATIGUE STRENGTH OF STEEL WIRE ROPES - PART III
Part I of this series of articles on "The fatigue strength of steel wire ropes", published in the October 1994 issue of Wire Industry, gave a study of the geometry of a rope. Knowledge of the geometry is of prime importance in calculating alternating tension.
Flection stresses, the subject of Part II, published in the January 1995 issue of Wire Industry, gave information on determining the stresses in a wire rope, particularly torsional stresses induced by bending.
This article, Part III in the series, discusses the stresses due to compression between wires in contact. Comparisons are made between ordinary and Lang's lay ropes.
DESIGN PROGRAMS FOR STEEL WIRE DRAWING
This system, which is extremely accurate, has been developed to calculate the exact dimensions and specifications for steel wire ropes and has been developed on a mathematical and analytical basis.
The wire drawing programs are composed of: 1) The creation, modification and writing of files; 2) Drafting calculations and creation of machine characteristics files; 3) Production processes; 4) Calculation of strengths and power consumption during drawing; 5) Calculation of strengths and power consumption applied to specific machines.
The hardware required is an IBM-PC compatible computer with a minimum of 256 kbytes, working under DOS and equipped with hard and floppy disks. A printer with al least 160 characters per line is also required.
FORCES, MOMENTS AND TWISTING ANGLES IN THE ROPES.
Different authors have tried to calculate the stress distribution as soon as to evaluate the torque or torsion moment of a rope under an axial load. But generally, in this studies only the strands (and generally with the composition 1+6) are considered, without study the more complex case of ropes with many layers of strands, such as Warrington-Seale or multilayer non rotating ropes. And the conclusions are theoretical and can not be easily applied to the normal practice.
In the preset paper we obtain expressions that are applicable to any strand or rope, without limitation of composition, or characteristics such as the strand or wire layers. This expressions have been introduced in a computer program very easy to use, and the results are very accurate.
We demonstrate that the long ratios Lay / Rope diameter involves a big torque, and conditiones strongly the uncabling of the rope; while the short ratio implicates, together with a low torque, an important lose of breaking load..
On the other hand, the device constructions of the cabling machine, such as pre or postformers, and the practice of the user must be considered.
So the correct solution is a problem of compromise that can be easily solved with the program.