SU1245443A1 - Method of ultrasonic welding of plastic articles - Google Patents

Description

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The invention relates to the welding of plastics, in particular to ultrasonic welding, and can be used in various fields of national economy, for example, in instrument making, machine building, in the aviation, automobile industry and other fields.

The purpose of the invention is to improve the quality of the weld.

In this case, the goal is achieved by improving the formation of the weld in the process of welding and cooling the weld by creating a tension between the parts to be welded and a recess in the welding tool in which the weld is placed, and also by avoiding displacement of the welded (/ parts relative to each other). about

The welding process is by limiting the rates of the plastic parts, and the upper displacement of the recess in the welding tool by the walls.

The drawing shows a scheme for implementing the method.

The method of ultrasonic welding of plastic parts is as follows. ,

In support 1 install the welded parts - pipe 2 with a bottom 3, carried out their Assembly. The connected surfaces of the parts are compressed with an ultrasonic welding tool 4, input with tension S pipe 2 with bottom 3 in order to blunt the welding tool to the stop into its working GEO-surface 5 at a depth of N. the presence of chamfer contributes 6. Due to the deepening of the working surface of the welding tool, the welded joint is located in a recess, tightly pressed against the side walls of the yoke. The welding pressure Q is applied to the parts, pressing the working surface of the welding tool to the parts to be welded, and a pulse of ultrasonic energy is fed from the magnetostrictive transducer 7. Parts 2 and 3 are welded together. Entering the welded parts into the welding tool with tension and placing the welded joint 8 in the recess of the welding tool provides counter pressure in the heating zone of the welded parts preventing their thermal destruction by preventing gaseous decomposition products of thermoplastics from splitting in the weld zone. This creates the conditions for obtaining

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a high-quality welded hermetic joint eliminates the swelling of the weld and the formation of flash.

The magnitude of the tension between the radial dimensions of the recess and the parts to be welded into it is within the range of 0.1-0.12 mm. The depth H of the insertion of parts into the welding tool is determined by the ratio

H S + 1.56 MM;

where S is the thickness of the welded part (the bottom of the pipe), mm;

 B is the width of the weld, mm.

The magnitude of the tension and the depth of insertion of the parts are established experimentally. The lower limit of the magnitude of the tension is determined, according to the technological possibilities of obtaining exact dimensions.

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from the considerations of excluding backlash of parts. - in the recess, i.e., providing guaranteed tension. When determining the amount of recess using metallographic research, it was found that the depth of insertion of the welded parts into the welding tool exceeding 1.5 V (B - weld width) thickness of the pipe bottom (S) ensures reliable locking of the seam in the recess. At the same time, not only the weld, but also the heat-affected zone does not extend beyond the end of the welding tool when welding the bottom with the pipe with the bottom thickness and, accordingly, the pipe wall up to 2 mm. I

Example. Did the weld

housing with the bottom of the product ZPG-21 (piezoelectric gas lighter), made of polyamide PAB-210/311, OST 6-06-C9-76. Case wall thickness 1.8 mm, bottom

1.5mM On the bottom around the perimeter there is a triangular hub of height O ,, 6 cm. Welding was performed on the installation: MTU-1,5-ZU4 in the following mode: frequency 22 kHz; anode current i 1jO A ;; bias current 16 A; welding pressure 2 atm; duration of compression 2 s; time; 3.4 s; duration of forging

3.6s After welding, a smooth weld was obtained without reinforcement and rounding; there is no displacement of the body and bottom in the radial direction. Tests on the welded joints for leaktightness were performed as follows. Valve-sealed cylinder

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(body with bottom) was filled with a liquefied gastightness criterion was

nym gas having the composition: propane is the absence of gas bubbles, yield 8%, n-butane 35%, isobutane - the rest of the weld. As a result

New, and held in a bath with water, tested 2 thousand pieces of cases

having a temperature of 25 + 5 ° C, a W07 "hermetic

3 ± 0.5 min. Welds.

Claims (2)

METHOD OF ULTRASONIC WELDING OF PLASTIC PARTS, including α assembly of parts, compression of the connected .Surfaces. by ultrasonic welding-> welding tool, application of welding pressure to them and introduction. . ultrasonic vibrations, characterized in that, in order to improve the quality of the weld, the compression of the joined surfaces is carried out by introducing parts with interference into the welding tool to a depth of H, determined from the ratio H = S + 1.5V; where S is the thickness of the welded part, mm; In - the width of the weld, mm SU ,,, 1245443 2.