Measurement Parameters of Ultrasonic Oscillatory System during ...

4MEASUREMENT PARAMETERS OF ULTRASONIC OSCILLATORY SYSTEM DURING WELDINGTHERMOPLASTICS2. Value of a current on oscillatory system.3. Oscilation frequency UOS.4. A phase difference of a voltage and a current onoscillatory system.5. A phase difference between two any periodic signals(from the basic generator, a feedback, a current or avoltage on oscillatory system).For management of job of the measuring complex andas recordings and processings of the measuredinformation the personal computer is used.Communication is carried out by means of protocol RS-232.During ultrasonic welding continuous measurement ofamplitude current of mechanical branch UOS I,amplitudes of electric voltage U, a phase angle between avoltage and current φ(I, U), a phase angle between avoltage on oscillatory system and feedback signal φ(I,Os), a phase angle between a voltage and a signal basicfrequencies φ(I, Op) was made (figure 2).In figure 2 dependences of electric parameters UOS atan absent material are presented (radiation to air).During welding at an absent material value of currentI, voltage U and phase angles φ (I, U), φ (I, Op), φ (I,Os) are saved by constants during all period of ultrasonicaffecting. In this case parameters UOS remain toconstants, because of absence of effect on oscillatorysystem, changing properties of a welded material duringwelding.Dependences presented in figure 3 illustrate effect ofchanging properties of a welded material in a weld zone(a softening of a polymeric material and transition in a isviscous-plastic condition) on electric parametersoscillatory system. There is a change of followingmagnitudes: I, U, φ(I, U), φ(I, Os) and φ(I,Op).From dependences presented in figure 3 follows thatprocess of welding can be broken into 3 stages:1. Change of a welded material from a solid conditionin is viscous-plastic. At this stage there is a decrease ofvalue of current I and voltage U on oscillatory system,increase in a phase angle between a voltage and a currentφ(I,U), and values of phase angles φ(I,Os) and φ(I,Op)remain practically constant.2. The Is viscous-plastic condition. At this stage thereis maximum damping oscillatory system. Values ofcurrent I and voltage U attain the minimal value, andmagnitude of a phase angle between a voltage and acurrent φ(I,U) on oscillatory system attains the maximumvalue.3. Change of a welded material from a is viscousplasticcondition in is viscous-fluid. At this stage there isan intensive smelting a material in a weld zone. Excessesof the fused material start to be extruded from a weld zonethat reduces welding pressure on oscillatory system. Thereis an increase in value of current I and voltage U onoscillatory system, decrease of a phase angle between avoltage and current φ(I, U).One of key parameters of ultrasonic welding is weldingpressure.In figure 4 some dependences of the current flowingthrough piezoceramic elements oscillatory system atwelding of equal specimens on thickness frompolypropylene at changing welding pressure on a materialare presented.From the presented dependences follows, that, atwelding equal specimens on thickness, curves of a currentcan differ essentially from each other. It is connected, firstof all, with various force of welding pressures on weldedmaterials, both during the initial moment, and during allprocess of welding.Carried out researches have shown, that at effect of bigwelding pressures there is strong damping UOS owing towhat it is not formed a qualitative welded joint. On theother hand at small welding pressure also it is not formeda qualitative welded joint, owing to insufficient energyforwarded in a weld zone.Thus, for implementation of the qualitative joint ofmaterials it is necessary to expel effect of instabilitywelding pressures at ultrasonic welding, i.e. to expeldistortions of curves of a current.From the gained results necessity of search optimumwelding pressures during ultrasonic welding follows.The further jobs will be directed on search of optimumparameters of ultrasonic welding thermoplastic materials.IV. CONCLUSIONAs a result of the spent researches have been solvedfollowing individual problems:1. Measurements of electric parameters UOS duringultrasonic welding are carried out;2. Effect, changing properties of welded materials onparameters UOS is determine;3. Eeffect welding pressures on electric parametersUOS Is researched;4. Optimum regimes for implementation of ultrasonicwelding with the maximum effect are installed.5. Criteria of automatic determination of optimumregimes of ultrasonic welding of various materials invarious conditions are determined.REFERENCES[1] Volkov S.S., Cherniak B.J. Welding of plastic usingultrasound, Chemistry.[2] Volkov S.S., Orlov U.N., Astahova R.N. Weldingand agglutination of plastic. М., «Machinery», 1972,128 с .[3] Zaysev K.I., Matsuk L.N. Welding plastic. М.,«Machinery», 1978.[4] Holopov JU.V. Ultrasonic welding of plastic andmetals. "Mechanical engineering", 1988.[5] Khmelev V.N., Slivin A.N., Barsukov R.V.,Tsyganok S.N., Savin I.I., Shalunov A.V., LevinS.V., Abramov A.D. "Development of the New