SU710818A1 - Ultrasonic method of welding polymeric materials - Google Patents

Description

The invention relates to the field of welding plastics, in particular to methods of ultrasonic welding of thermoplastic materials.

Methods of ultrasonic welding of polymeric materials are known, in which the cessation of the effect of ultrasonic vibrations on the material being welded at the end of the joining process is performed by time, by a fixed gap between the end of the waveguide and the support, by changing the displacement amplitude of the support on which the materials to be welded are placed.

The disadvantage of the methods is that they do not allow to obtain a high quality stability of the welded joints.

The closest to the proposed one is the method of welding on a fixed draft, including the application of static pressure to the materials being joined, the transmission of ultrasound, the measurement of the deformation of the welding zone and the automatic

thematic shutdown of ultrasound after reaching a certain deformation value (fixed sediment) 2}

The disadvantage of this method lies in the fact that for cutting {b x K1 materials, the geometry of the parts and the welding direction it is necessary to experimentally determine the optimal draft, which requires additional costs of time and reduces productivity; the stability of the strength characteristics is not ensured, which is due to the different thickness and heterogeneity of the properties of the parts being welded.

The purpose of the invention is to increase the process efficiency and strength of the welded joint.

This goal is achieved by the fact that in the method of ultrasonic welding of polymeric materials, including the application of static pressure to the joints of MaTcpisanof-s, ultrasound transmission, measurement of the zone deformation and automatic shutdown of ultrasound for the intended de (welding zone of the welding zone during the transmission of ultrasound) The acceleration of deformation and the switching off of ultrasound are carried out when the acceleration of deformation is achieved with a positive (O1X) value. Such an implementation of the method improves the productivity of the process and the weldedness of the joint. Regardless of the thickness of the parts, the properties of the material from which they are made, and the welding modes, automatic switching off of the sound is made after the formation of the connection of the contact surfaces of the parts being welded. This causes intense heat dissipation in the inner layers of the parts adjacent to these surfaces, which sharply reduces their resistance to deformation and is accompanied by an increase in the speed of deformation - pushing,. the appearance of accelerated deformation of a positive sign. The drawing shows the characteristic curves of the dependence of the deformation acceleration (curve 1) and the strength Q of welded joints (curve 2) versus the welding time -b, from which it follows that the maximum strength of the joint is achieved at the moment of acceleration of a positive sign. The method is carried out as follows. The tape is based on a nylon Eulocon brand LTK-5O-15OO, a spike of 1.7 mm, width boom. Welding prodv d11ts with an exponential knife waveguide with one longitudinal seam 50 mm long and 5 mm wide. After applying a static pressure to the tape and switching on ultrasound with the help of a differential transformer displacement transducer of the DG1-3 type, the deformation of the weld zone is continuously detected. The signal from the sensor is differentiated twice to determine the acceleration of the deformation, and when a positive sign appears to accelerate using a sign discriminator that transmits only signals corresponding to the positive acceleration, ultrasound is automatically turned off. To compare the results, a well-known welding method is performed in parallel with the shutdown of ultrasound at a fixed draft, which is pre-selected experimentally. Welding of samples according to the proposed and known method is carried out on the same modes. On each mode, 5O samples are welded, according to the results of which tensile tests determine the static strength characteristics of the welded joints. The results are tabulated.

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Famous

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Proposed

O, 4776125.3 1v, 14

84268,88,17

O, 44605.5105.4 17.42

67O, 050,47,52

0.5585,387.7 14.98

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625.042.56,

Claims (1)

Claim A method of ultrasonic welding of polymeric materials, including applying static pressure to the materials to be joined, transmitting ultrasound, measuring the deformation of the welding zone and automatically turning off the ultrasound, characterized in that, in order to increase the productivity of the process and the strength of the welded joint, according to the measured deformation of the welding zone during the transmission of ultrasound record the acceleration of deformation and the shutdown of the ultrasound is performed when the acceleration of deformation is positive Niya.