METHOD OF ULTRASONIC WELDING OF PLASTICS Russian patent published in 2004 - IPC

FIELD: ultrasonic welding of thermoplastics.

SUBSTANCE: the invention presents a method of ultrasonic welding of plastics, in particular- ultrasonic welding of thermoplastics and may be used in production of synthetic woven tapes (connection of safety belts), imitation leathers, soundproofing synthetic woven mattresses with a synthetic nonwoven filling typing, at connection of solid thermoplastics, especially of those requiring a long duration of the welding process. The method provides for: stacking of the details to be welded between a waveguide and a support; squeezing of these details; switching on the welding pressure of the given value and the ultrasonic oscillations of the waveguide with the given value of the amplitude and the frequency of oscillations of the working butt and the given time of transit of these oscillations;, registration of transit time of the ultrasonic oscillations, amplitude, frequency and the welding pressure. Simultaneously with the switching on of the ultrasonic oscillations the given time of transit of these oscillations is permanently replaced with the calculated values determined depending on instantaneous values of the registered parameters of the welding mode by the following formula: where t_ins - is an estimated time of transit of the ultrasonic oscillations, corresponding to the instantaneous values of parameters of the welding mode; t₀ - is a preset time of transit of the ultrasonic oscillations, corresponding to the instantaneous values of parameters of the welding mode; f₀- is the given frequency of the ultrasonic oscillations; A₀ - is the given amplitude of the ultrasonic oscillations; P₀ - is the given welding pressure; P_к- is the pressure, at which there is the acoustic contact providing a capability of a welding; it is determined experimentally; f_ins- is an instantaneous value of the frequency of ultrasonic oscillations; A_ins- is an instantaneous value of the amplitude of ultrasonic oscillations; P_ins- is an instantaneous value of the welding pressure. The calculated time of transit of the ultrasonic oscillations is compared with the running time and in case of their equality they switch off the ultrasonic oscillations. Then the welding pressure is switched off and hoist the welding head is raised. The invention ensures to achieve high stability of quality of welded connections.

EFFECT: the invention ensures to achieve high stability of quality of welded connections.

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