SU903161A1 - Method of ultrasonic welding of polymer materials - Google Patents

Description

(5t) METHOD OF POLYMERIC ULTRAWEAK WELDING The invention relates to the field of welding of plastics, in particular to the field of ultrasonic welding of materials from. fine particles and fibers. The known method of formation of compounds inside a polymer material by heating it in a mold with simultaneous action of squeezing force and ultrasonic vibrations 01 The disadvantage of this method is that as a result of heating in the mold, the structural grains of the components are softened, which eliminates the possibility of bond formation between the grains of the components without destroying the latter. The closest in technical essence and the achieved result to the invention is the method of ultra sound welding of polymeric materials, including the compression of the material and the impact on it by ultrasonic vibrations 21, MATERIALS The disadvantage of this method is that when welding material in the form of solid particles or fibers prolonged continuous action of ultrasonic vibrations leads to the complete destruction of the structural components and the reduction of the strength properties of the material as a result of overheating and destruction instructions. The aim of the invention is to increase the strength of the compound material in the form of solid particles or fibers. . This goal is achieved by the method of ultrasonic welding of polymeric materials, including compression of the material and the impact on it of ultrasonic vibrations, ultrasonic vibrations on the material are periodically affected with a period of time varying exponentially. The duration of the first period is determined by the beginning of the melting of the particles at their boundaries,. after each period, the effect of ultrasound vibrations on the material is maintained under pressure until the material is cooled below the crystallization temperature. This ensures the formation of interconnects inside the material without disrupting the original structure. FIG. Figure 1 shows the nffot ecc diagram of the formation of interconnects of a material; in fig. 2 is a graph of the change in the duration of the inclusions of ultrasonic vibrations. The method of ultrasonic welding is as follows. The material, compressed by force P, is subjected to periodic oscillations transmitted from the ultrasonic tool 2, and the maximum ultrasonic energy is absorbed in the zone located near the radiating surface of the tool 2, where 8 the result of boundary friction between the surfaces of the particles (fiber components) occurs can be recorded in terms of the value of shrinkage. The last 4 uetanshistvatsya experimentally and depends on the physicomechanical state of the welded mother an. After reaching a certain siege or later Bpeiwi {ultrasound is turned on and the material under pressure is kept until complete Hfl and crystallization, with the Los losM soften interlayer of solidification of the g | h is less capable of absorbing ultrasonic oscillations, since the interfaces, which are the main energy absorber of the ultraSonic, disappear. When the second impulse of ultrasonic oscillations is switched on, the ultrasonic ultrasound through jay hjy is transmitted to the layer h, in which again along the boundaries of the particles, as a result of boundary friction, heat is generated and compounds are formed, i.e. the process inside the h layer repeats typically, as in the HO layer. However, due to the fact that the absorption in the layer h still exists, the time f of the second ultrasonic vibration pulse is reduced to such a time that the material in the layer B does not heat up above temperatures that violate its structure, such as orientation of the polymers or complete melting of the particles. Therefore, the layer thickness h becomes smaller than h, and the layer thickness, etc. It should be noted that in the actual process of internal welding there is a clear boundary between the layers, etc. We exist. It was established experimentally that, from the point of view of obtaining the greatest strength properties of various materials, the optimal time for ultrasonic pulses is to reduce the exponential law, tn –Co e, where ti, and the first and subsequent periods of switching on the ultrasonic vibrations, respectively; p - period number; D is the absorption coefficient of ultrasonic vibrations in a given material. The invention is illustrated by examples of the method. Example 1. A blank of an unvulcanized mixture of synthetic rubber BK and SKN-26, carbon black and other materials that were in a vitrified state, the finished product for which is a sample in the form of a jgj cylinder 50 mm and a height of 20 mm, was subjected to ultrasonic welding under the following modes: Static pressure 5 kgf / sn / Amplitude of ultrasonic vibrations 30 microns Frequency of ultrasonic 20 KHZ Duration of the first pulse of ultrasonic vibrations 0, 3 s Number of pulses n 8. As a result of ultrasonic welding were obtained strength indicators characterizing the material after its welding (see tab.1).

Table 1

Resistance ripped

Example 2. A blank of layers of nylon cord and rubber mixture arranged in layers in a glass-clad state, the finished product of which is a sample. with a diameter of 50 mm and a height of 10 mm, was subjected to internal welding with the following mode parameters:

Processing type

Calendered material

Material obtained by internal welding with the duration of the initial pulses

0.3 s 0.5 s 0.8.s.

The length of the first impulse of ultrasonic vibrations, 5 sec. The number of impulses p 5 8 as a result of welding between the monofilaments of the kapron cord and the rubber mixture, the following indicators were obtained about the rigidity when tested on a rubber wheel in kgf / cm (cm, Table 2) .

: T a 6 l and c a 2

Test On razdir, in to GS / cm (aulkaniz.)

23

Claims (2)

29 2 33 79 The test results given in Table 2 show that the optimum welding mode is at 0.5 s. The method of ultrasonic welding of composite materials can be used in various processes related to the processing into products of individual materials, powders and mixtures of various powders and solid masses and particles, fibers and mixtures of them with various powders, solid masses and other substances. in different physical states. The method of ultrasonic welding has been tested during welding between various components that are included in the rubber-rubber mixture, from which later the frame New car tires bracelets. The pavement1 was tested in road conditions and showed an increase in mileage of 20-30 compared with serial ones, which allows saving raw materials and labor costs in the amount of 8-10 million rubles for each .1 million passenger tires produced in the USSR. 8 61 The claim of the method of ultrasonic welding of polymeric materials, including compression of the material and exposure to ultrasonic vibrations, characterized in that, in order to increase the strength of the joint material in the form of solid particles or fibers, ultrasonic vibrations on the material are periodically affected with a duration of periods, in this case, the duration of the first period is determined by the beginning of melting of the particles at their boundaries, and after each period of exposure the ultrasound and the wobbles on the latter material is maintained under pressure until material cooling below the crystallization temperature. Sources of information taken into account in the examination of T. Basov N. I., et al. Vibroforming of olimers. L., Himi, 1979, p. 93. 2. Volkov S.S. and others. Plastass ultrasound welding. M., Himi, 197,. (prototype).