SU1245442A1 - Method of butt welding of polymeric articles - Google Patents

Description

The method relates to the field of welding plastics, in particular, to the methods of butt-welding of profile products from thermoplastic materials having a narrow interval of viscous flow and low viscosity in this state. The purpose of the invention is to increase the penetration of the welded joint in welding parts made of polyamide.

This goal is achieved due to the short duration of the polyamide being above the melting point and the associated decrease in the degree of oxidation and decomposition of the polyamide melt, as well as due to the presence of shear deformations in the weld seam area, the normal joint plane and the associated melt mixing process.

FIG. 1 shows the process of joining parts and heating the joint zone; in fig. 2 - input of ultrasonic vibrations; in fig. 3 - forming device, longitudinal section; in fig. 4 - the same cross section.

The method of butt welding of parts from polymeric materials is as follows.

Sectors 1 and 2 of the product are fixed in fixed 3 and mobile 4 clamps, respectively, and joined with application of welding force so that the joint is located in the middle of the heaters 5 of the forming device consisting of two detachable half-form-upper 6 and lower 7. Heaters 5 are made of nichrome wire and placed in the middle of the half-form in the grooves along the profile of the product.

Heaters 5, connected to the power source, heat the stalk zone to a highly elastic state (Fig. 1). The heating temperature is controlled with a thermocouple or pre-installed on the voltage source corresponding to the heating temperature.

After the polyamide is heated in the sanding zone to the highly plastic state, ultrasonic tool 8 is inserted into the joint zone by ultrasonic vibrations (Fig. 2).

To prevent significant deflection of sector 2 and to ensure constant contact of the radiating surface of the ultrasonic instrument

This 8 with the surface of sector 2 under the tool 8 is preliminarily installed an elastic support 9 made of rubber. For: providing a larger contact area between the tool and the product, the radiating surface of the tool 8 has the profile of the product to be welded.

Ultrasonic vibrations are introduced into the joint zone through one of the parts, in particular, sector 2, secured in a movable clamp. Ultrasonic vibrations are inputted at a distance from the straining equal to half the length of the transverse wave, tangentially to the plane of the joint. Under the action of ultrasonic vibrations, the heated material in the joint zone is heated up to the flowable state and intense mixing of the melt occurs.

Since the greatest losses of ultrasonic energy occur in the highly elastic state of polyamide, the temperature rises faster in the joint zone after preheating than in other areas that are in normal conditions in the glassy state.

In the case of the tangential introduction of ultrasound: to: ovpc: oscillations perpendicular to the plane of the junction are transverse oscillations. Transverse vibrations promote mutual penetration of melts of the edges being welded. Therefore, stich is rationally placed at a distance from the place of input of ultrasonic vibrations equal to a transverse wave, i.e., in places of maximum amplitude of transverse oscillations, where L is the wavelength, and n is a natural number.

Entering ultrasonic vibrations from the movable clamp side allows new cold layers of material to come into contact with the ultrasonic tool during the welding of parts, as a result of which the conditions of ultrasonic energy transfer are kept constant during the welding process and the material melts at the insertion point of ultrasonic vibrations.

Example. A polyamide cuff was welded in accordance with MH5652-65 from one of four sectors. The sectors were welded in a device that provided the required cuff diameter. The ultrasound system consists of a UZG-4M generator and an IIMC-15 transducer. The ultrasonic instrument has a conical or stepped shape.

Optimum welding conditions were determined as a result of preliminary studies and testing of tensile samples according to GOST 11262-80.

During the research, the following welding parameters were changed:

preheating temperature T 160 -

pressure

The distance from the joint to the ultrasonic instrument S O is 40 mm.

Samples were welded using the following constant welding parameters:

precipitation 0.08-0.20 MPa

five

frequency of ultrasonic vibrations f 20 kHz;

amplitude of A 35 - 40 microns;

the duration of ultrasonic vibrations t y 1.0 - 1.5 s.

Strength in tensile testing of the base material is 3.95 kg / mm.

The greatest strength of the welded joint is obtained at the preliminary zone of the joint

on

the melting point of polyamide 610 and corresponds to the highly plastic state of the polyamide; using a precipitation pressure of 0.12 MPa; introducing ultrasonic vibrations at a distance of 15 mm from the joint.

nom heated

tours 210-215 ° C, what

to temperature 6-11 lower

SJ

Fllz.2

FIG b

Editor A. Sabo

Compiled by N. Eliseev

Tehred O. Sopko Proofreader E. Sirohman

Order 3947/9 Circulation 640 Subscription

VNSHPI USSR State Committee

for inventions and discoveries 113035, Moscow, Zh-35, Raushsk nab., 4/5

Production and printing company, Uzhgorod, st. Project, 4

Figm

Claims (1)

METHOD FOR BUTT WELDING OF PARTS FROM POLYMERIC MATERIALS, including heating the joint zone of the parts, tangential introduction of ultrasonic vibrations into it, joining and compressing the parts with application of welding pressure, characterized in that, in order to increase the strength of the welded joint when welding parts from polyamide, heating the joint zone parts are carried out until a highly elastic state of polyamide is achieved, and ultrasonic vibrations are introduced into the joint zone after it is heated through one of the parts at a distance q from the joint, equal to half the length transverse wave, moreover, the docking and compression of parts is carried out before heating the joint zone.