Investigation of the flexural and torsional rigidity of flexible elements of endoscopes

Conclusions

1. Methods and a device were developed for determining both under laboratory and production conditions the flexural and torsional rigidity of flexible endoscope elements. The documentation on the indicated methods and device were supplied to industry.

2. The flexural rigidity of the uncontrollable working part of the Olympus (Japan) medical endoscopes is two-stage. In the distal part on a section up to 0.36–0.4 m it has a value of 7.3 kgf/cm² for single-channel colonofibroscopes and 10 kgf/cm² for two-channel colonofibroscopes and on the remaining section (closer to the control casing) it is 50% greater.

3. The flexural rigidity of the uncontrollable working part on a section 0.1–0.2 m from the distal end for ACM (USA) single-channel colonoscopes is 1.3 times greater than for the Olympus (Japan) ones. In the section greater than 0.2 m the flexural rigidity of the ACM colonoscopes is multistage (it has five sections with a different rigidity) and in different sections has values 1.3–3.7 times greater than that of the Olympus colonofibroscopes.

4. The flexural rigidity of the uncontrollable working part of the ACM two-channel colonoscopes is 2.8–2.4 times greater than in the Olympus colonofibroscopes.

5. The outer polyurethane coating made by the extrusion method on stainless steel braiding bears the greater part of the torsional rigidity (62%) of the uncontrollable working part of the Olympus colonoscopes.

6. The results of investigating the flexural and torsional rigidity of the working part of flexible foreign endoscopes made it possible to give recommendations on the design and improvement of the working part of Soviet flexible endoscopes.