The Effect of Thermal Energy Concentration on the Strength of Welded Surfaces in the Ultrasonic Welding of Plastics

The article presents the results of a study to optimize edge preparation in order to meet technical and aesthetic requirements to the finished product. To increase energy concentration on the butting welded surfaces, V-shaped edge preparation is selected. An analysis of the thermal regime of polymer welding and the kinetics of weld joint formation is performed. It is established that the optimal value of the V-groove lies in range of 45 degrees, at which the maximal strength and tightness of the weld joint are reached. When welding parts made of rigid plastics, it is necessary to consider them as a separate element in the single acoustic system transducer–sonotrode–welding parts–anvil. The mechanism of weld joint formation during ultrasonic welding of plastics is described. It is shown that thermal emission on welding surfaces is due to internal friction. It is established that the V-shaped edge preparation leads to predominant heat formation at the boundary and is caused by an increasing level of dynamic stresses, which contributes to the acceleration of the ultrasonic welding process. Edge preparation increases the strength of the weld joint, improves its appearance and reduces the time of ultrasonic welding.

References

[1] Volkov S.S. Svarka i skleivanie polimernykh materialov [Welding and bonding of polymeric materials]. Moscow, Khimiia publ., 2001. 376 p.

[2] Volkov S.S. Tekhnologiia ul’trazvukovoi svarki mnogoelementnykh izdelii iz zhestkikh plastmass [The technology of ultrasonic welding of multi-element products of rigid plastics]. Svarochnoe proizvodstvo [Welding International]. 2003, no. 10, pp. 35–39.

[3] Volkov S.S. Ultrasound welding of brush elements. Welding International, 2012, vol. 26, no. 10, pp. 796–799.

[4] Karkhin V.A. Teplovye protsessy pri svarke [Thermal processes during welding]. Sankt-Petersburg, Politekhnicheskoii universitet publ., 2013. 646 p.

[5] Volkov S.S., Nerovnyi V.M., Maloletkov A.V. Tekhnologicheskie osobennosti ul’trazvukovoi svarki zhestkikh plastmass v vakuume [Technological features of ultrasonic welding of rigid plastics in a vacuum]. Svarka i diagnostika [Welding and Diagnostics]. 2015, no. 6, pp. 29–32.

[6] Volkov S.S. Technology for ultrasonic welding multi-element components produced from rigid plastics. Welding International, 2004, no. 18(3), pp. 242–245.

[7] Volkov S.S. Main methods and technological features of welding dissimilar plastics. Welding International, 2008, no. 22(3), pp. 193–197.

[8] Volkov S.S. Effect of fillers and dyes on weldability and service properties of ultrasound-welded joints in plastics. Welding International, 2010, no. 24(9), pp. 734–737.

[9] Volkov S.S. Ultrasound welding of brush elements. Welding International, 2012, vol. 26(10), pp. 796–799.

[10] Volkov S.S. Ultrasonic butt welding of rigid plastics. Welding International, 2013, vol. 27(3), pp. 63–66.