Slotted Springs Research Articles

Hydropulse small-sized vibrators based on slotted springs

The article presents constructions and descriptions of the principles of operation of single-stage pressure pulse generators which are the main elements of the hydropulse drive used to generate vibrations of actuators in vibrating and vibratory shock machines for various purposes. Namely the pressure pulse generator with a solid body the pressure pulse generator with a floating seat and the pressure pulse generator with valve sealing degrees which were developed on the basis of Vinnytsia National Technical University. In the considered devices have the slotted spring as an elastic element which is executed as a separate detail or as a constructive element of other details which are a part of the device is used. The use of such elastic elements allows to ensure the speed of the devices and accordingly to increase the frequency characteristics of their operating modes. It is established that hydropulse vibrators - hydraulic cylinders based on cut or ring springs have the smallest dimensions with significant vibration force parameters.The text of the article highlights the main conditions for stable operation of these pressure pulse generators indicates and analyzes the mathematical dependences between the operating parameters of devices and the size of their structural elements offers the necessary correlation between structural dimensions of working surfaces of actuators and features of their positional parameters. The offered mathematical dependences can be used both for optimization of work of the designs of devices considered in article and at designing of new generators of pressure pulses with the hydropulse drive of various function. The shortcomings of individual designs of pressure pulse generators which may be related to the ways of sealing the working chambers of devices or options for interaction of structural elements of the device are identified and considered.

ASSESSMENT OF MECHANICAL CHARACTERISTICS OF VASCULAR ENDO-PROSTHESES

Titanium nickelide (nitinol) is one of prospective materials for production of special endo-prostheses and other parts and characterized with effect of shape memory. A specific feature of vascular endo-prostheses is the necessity to provide the required rigidity within the temperature interval from 15 to 42 оС. It has been established that titanium nickelide is able to provide the required rigidity but it depends on preliminary heat treatment parameters. So, it is important to determine rela-tions between rigidity of titanium nickelide wire and its preliminary heat treatment parameters for the given temperature in-terval. The aim of the work is to create devices that allow to estimate radial and flexural rigidity of elements made of flexible nitinol wire for manufacturing various medical products, including endo-prostheses of vessels – stents and stent grafts, filter traps. Laboratory digital scales and a specially developed dynamometer based on a cylindrical slotted spring and inductive displacement transducer have been used for measuring a load. The paper proposes possible variants of device designs used to monitor radial rigidity of blood vessel endo-prostheses, as well as to control flexural rigidity of endo-prosthesis elements and wire for their manufacture. The developed devices allow us to evaluate mechanical characteristics of samples under the desired temperature conditions. An introduction of the developed devices has permitted to carry out an operative control on radial and flexural stiffness of intravascular endo-prostheses elements both under conditions of research investigations and during technological process of their manufacture. Currently, the devices are used to specify heat treatment regimes for nitin-ol wire from various manufacturers while manufacturing vascular endo-prostheses.