RU2758710C2 - Vacuum induction soldering method - Google Patents

Abstract

FIELD: soldering.

SUBSTANCE: invention can be used to obtain beryllium or tungsten cladding on a bronze heat-removing layer of components of a thermonuclear reactor by high-temperature soldering. A water-cooled copper inductor is mounted inside a vacuum chamber, which has a passage section on one side for free access of a soldered product to a working area of the inductor. Quick-hardened amorphous solder is placed in a soldering zone. Preliminary slow uniform heating of the entire product is carried out to the maximum temperature, which does not lead to a decrease in the strength of heat-sensitive material of the product. Then, heating is carried out to a soldering temperature of high-temperature solder, followed by turning off the heating. Control and regulation of the soldering temperature is carried out using a control system that provides a set heating mode. A gap between the product and the inductor is adjusted for a given temperature distribution in soldering zones by moving part of the inductor by means of electrically isolated rods connected to it along the entire length.

EFFECT: invention provides for the production of high-quality soldered joints, while maintaining the strength of heat-sensitive material of the product located in the soldering zone, not lower than 70% of the initial one.

1 cl, 5 dwg

Description

Technology area

The invention relates to the field of engineering and technology of soldering products with high-temperature solder in a high-frequency field of an inductor in a vacuum environment, and can be used, for example, in the process of soldering a beryllium or tungsten cladding onto a bronze heat-removing layer of the components of the ITER fusion reactor facing the plasma.

State of the art

The known method of induction soldering and a device for its implementation, disclosed in the source of information (Vologdin VV and other Induction soldering. - L .: Mechanical engineering, 1989). At the same time, this known method includes the installation of parts connected by solder, fixed by a tooling, into the working area of the inductor, setting the parameters of the soldering mode and heating the soldering zone due to eddy currents induced in the parts by the high-frequency electromagnetic field of the inductor. The device for implementing this method includes: a water-cooled copper inductor developed for a given configuration of the product, including a through-feed type, to enable the product to move relative to the inductor; high frequency power supply; soldering temperature control devices, including thermocouples; a mechanism for feeding products, including those assembled in fixing equipment, to the soldering zone and back.

However, in the proposed soldering method and the device that implements it, it is not possible to ensure the minimum residence time of the product in the high soldering temperature phase, while maintaining the necessary and uniform heating of the entire soldering zone. This leads to a strong decrease in the strength of the pre-hardened heat-sensitive material of the article, for example, chromium bronze used in the plasma-facing components.

There is a known method of induction soldering and a device for its implementation, disclosed in the materials of the patent (see RF patent 2296037, class В23К 1/002, В23К 3/04, 2003), which consists in the predominant heating of the technological substrate made of electrically conductive material, which heats the parts located on it and the solder, which leads to the formation of a soldered joint.

The disadvantage of this method is the need to introduce a technological substrate, the placement of which in the soldering zone is not always possible and is limited by the geometry and the initial requirements for the product. In addition, this method does not provide for the possibility of maintaining the strength of the material of the technological substrate. The technical result of using the invention is the elimination of the indicated disadvantages of the considered methods, obtaining high quality brazed joints and maintaining the strength of the heat-sensitive material of the product located in the brazing zone, not less than 70% of the original (before brazing).

Disclosed inventions

The specified technical result is provided by the fact that in the method of vacuum induction soldering, containing a vacuum chamber with a copper water-cooled inductor placed inside the chamber, having a passage section on one side, providing free access to the working area of the inductor of the brazed product with an amorphous fast-quenched solder previously placed in the soldering zone, as well as the installed fixture and fixed thermocouples, a control system that processes the readings of all thermocouples and controls the high-frequency power supply, according to the heating mode set by the operator, and the new one is that the heating mode has two phases, which allow first to perform preliminary slow uniform heating of the entire product to limiting temperature, which does not lead to a decrease in the strength of the heat-sensitive material of the product, after which to perform rapid heating to the required soldering temperature of the high-temperature solder, followed by switching off the heating, It has electrically insulated rods connected to it along the entire length, which allow adjusting the gap between the product and the inductor in the required places, which allows to achieve optimal uniformity of temperature distribution throughout the soldering zone at all heating phases.

Brief Description of Drawings

The essence of the invention is illustrated by graphic materials on which:

in fig. 1 - soldered product and inductor, top view;

in fig. 2 - view A according to FIG. 1;

in fig. 3 - section B-B according to Fig. 1;

in fig. 4 - section B-B according to FIG. 1;

in fig. 5 is a graph of a heating mode with two phases.

The method of vacuum induction brazing contains, located inside the vacuum chamber, a copper water-cooled inductor 1, which has a passage on one side, to provide free access to the soldered product 2 with an amorphous quick-hardened solder previously placed in the brazing zone, as well as an installed fixing equipment and fixed close to the brazing zone thermocouples (accessories and thermocouples are not shown) into the working area of the inductor 1.

Copper posts 3 with threaded holes are soldered to the inductor, in certain places along the entire length, into which threaded rods are screwed 4. Rotation of nuts 5 or 6, abutting through electrical insulating inserts 7 and 8 into movable posts 9, drives threaded rods 4, together with which part of the inductor 1 moves, and the size of the gap between the inductor 1 and the product 2 (A1 size) changes locally.

The profile of the inductor 1 repeats the profile of the soldering zone along the entire length of the product 2. The position of the middle of the inductor 1 in height (A2 size) relative to the soldering zone on the product 2 is selected based on the analysis of the materials used in the product. The heating mode of the brazed product 2 includes a phase of preliminary slow heating 10, during which a uniform temperature of the entire product 2 is achieved to values below the temperature threshold at which the processes of loss of strength of the heat-sensitive material occur. The next phase 11 - rapid heating to a temperature of 20 ° C-30 ° C above the liquidus temperature of the solder, after reaching which phase 12 begins - free cooling in vacuum.

Implementation of the invention

The vacuum induction brazing method is as follows.

On the components of the soldered product 2, close to the soldering zone, thermonars are attached, the location of which and the total number will be determined depending on the standard size of the product 2.

All components of the brazed product 2 are completely cleaned and degreased, as well as etched mating surfaces in the brazing zone. Tape amorphous fast-hardened solder, selected for the conditions of soldering of specific materials of the product 2, is degreased and cut into elements of the required length, depending on the standard size of the product. The cut elements of the solder strip are placed in one layer on the surface of one of the components of the article 2, in our case, on the bronze surface of the base of the component facing the plasma. Further, the mating components of product 2 are installed on the solder strip, in our case, beryllium tiles of the protective lining. The assembled components of the product 2 are fixed with a tooling to prevent the components from moving relative to each other during assembly, heating and cooling. The fixation of the components should be carried out with a force that ensures the creation of pressure in the soldering zone not lower than the required value, the value of which is determined by analyzing the materials to be soldered, and, in the case of bronze and beryllium, is 0.05 N / mm ² .

Product 2 with installed fixing equipment and fixed thermocouples is placed inside the vacuum chamber of the technological unit until it touches the limit stops, getting into the working area of the water-cooled copper inductor 1. Inductor 1, made of copper pipe, is pre-bent so that its shape repeats the shape of the curved surface along which soldering of the components of product 2. By adjusting the position of product 2 in height, the position of the middle of the inductor 1 is adjusted relative to the soldering zone on the product 2 (size A2) - inductor 1 should be located closer to the material with a lower electrical resistivity coefficient (in our case, bronze). Rotating the nuts 5 or 6, move the threaded rods 4, which, through the copper posts 3, move the inductor 1, thereby changing the gap (A1 size) between the side wall of the product 2 and the inductor 1. The size of the gap (A1 size) should be from 4 mm up to 8 mm, while a smaller gap is set if it is necessary to obtain a greater heating power in this area, which is typical for the case when the product 2 in this area has a large cross-sectional size and higher heat capacity. By adjusting the gaps (sizes A1 and A2), the influence of the curvature of the brazing zone, the variability of the design of the part under the brazing zone (change in the cross section), the influence of edge effects are compensated. After completing the adjustment of the gaps (sizes A1 and A2), connect the leads of all thermocouples, close the vacuum chamber and evacuate the air from the chamber.

The parameters of the heating mode are entered into the automatic control system for the soldering process. The parameters of the heating mode are determined for each new standard size of the product and contain the speeds and durations in the preliminary slow heating phase 10, as well as in the fast heating phase 11.

Automatic heating is switched on, during which the automatic control system, according to the entered parameters and the feedback signal from the thermocouples installed on the soldered product 2, controls the high-frequency power supply and, accordingly, the heating mode. After reaching the required soldering temperature - 20 ° C-30 ° C above the liquidus temperature of the solder, the power supply is turned off. The used amorphous fast-quenched solder has a small melting temperature range of the incoming components and has time to quickly and completely pass into the liquid phase. The spread of temperature values of parts in the soldering zone at the end of the rapid heating phase should be +/- 3% of the nominal value, which is necessary for uniform wetting of the parts to be joined with solder.

After product 2 has cooled to a temperature below 200 ° C, air is admitted into the vacuum chamber, the chamber lid is opened, the thermocouple leads are disconnected, and the soldered product 2 with installed fixing equipment is removed from the vacuum chamber. Then the cycle is repeated similarly to that described above, except for the operation of adjusting the position of the inductor (sizes A1 and A2) in the event that soldering is performed for a product of the same standard size.

The use of this method of vacuum induction brazing provides high quality brazed seams, for example, the control of soldered seams facing the plasma components using ultrasonic testing methods with an assessment using a calibration sample with artificial defects (∅2 mm, ∅3 mm, ∅4 mm) is not identified defects in the connection. In addition, the use of this induction brazing method ensures that the strength of the heat-sensitive material of the product located in the soldering zone is not less than 70% of the original (before soldering), for example, the tensile strength (o "c) of bronze, when testing material samples for rupture at room temperature. temperature, before brazing was at least 360 MPa, and after brazing - at least 270 MPa.

Claims (1)

A method of vacuum induction brazing of a product made of a temperature-sensitive material, including placing an amorphous fast-quenched solder in the soldering zone of the product components, installing a soldered product assembled using fixing equipment and equipped with thermocouples in a vacuum chamber, inside which a water-cooled copper inductor is mounted, having a passage section on one side for free access of the soldered product to the working area of the inductor, while the soldering temperature is monitored and regulated using a control system that provides a predetermined heating mode, characterized in that heating is carried out in two phases, while first performing a preliminary slow uniform heating of the entire product to limiting temperature, which does not lead to a decrease in the strength of the heat-sensitive material of the product, and then heating is carried out to the soldering temperature of the high-temperature solder, followed by turning off the heating, while using an inductor whose profile is repeats the soldering zone of the product surface, and the gap between the product and the inductor is adjusted for a given temperature distribution in the soldering zones by moving a part of the inductor by means of electrically isolated rods connected to it along the entire length.

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