Brazing method for graphite-copper composite commutator

Abstract

The invention discloses a low-temperature brazing method for a graphite-copper composite structure commutator. The low-temperature brazing method includes the following machining steps: (1) preparing SnAgCuTi powder brazing filler metal containing the active element Ti, (2) placing the SnAgCuTi powder brazing filler metal on the surface of a graphite plate, heating the SnAgCuTi powder brazing filler metal and the graphite plate to be at the temperature ranging from 450 DEG C-900 DEG C under the vacuum or inert gas protection condition, keeping the temperature for 0 min-60 min, achieving metallization of the surface of the graphite plate, cooling the SnAgCuTi powder brazing filler metal and the graphite plate to be at the indoor temperature, and taking out the SnAgCuTi powder brazing filler metal and the graphite plate, and (3) assembling metallized graphite and a copper commutation blade, exerting the 0.2 MPa-1.2 MPa axial pressure, placing the assembly into a brazing device to heat the assembly to be at the temperature ranging from 240 DEG C to 450 DEG C, keeping the temperature for 0 min-60 min, and completing low-temperature brazing forming of the graphite-copper composite structure commutator. According to the low-temperature brazing method, the problems that in an existing brazing technology of the graphite-copper composite structure commutator, the combination strength between a metal plating layer and the graphite plate is low, and falling is prone to happening are solved, softening of the copper commutation blade is effectively relieved through the low brazing temperature, the performance of the graphite-copper composite structure commutator is improved, the service life of the graphite-copper composite structure commutator is prolonged, and the brazing method has the advantages of being simple, practical, environmentally friendly, efficient, easy to operate, stable in technology, low in cost and the like.

Description

technical field [0001] The invention relates to the field of welding technology, in particular to a brazing method for a graphite-copper composite commutator which is especially suitable for a DC motor commutator. Background technique [0002] The commutator is one of the most important structural components in the DC motor, and its quality has become an important indicator to measure the performance of the DC motor. Because copper has excellent thermal conductivity and electrical conductivity, it is widely used in various types of commutators. However, liquid fuels such as ethanol, gasoline, and diesel have a strong corrosion effect on the copper commutator blades of the motor commutator, resulting in When the commutator is working, the discharge phenomenon is serious and the sparks increase. At the same time, the lubrication between the copper and the carbon brush is poor and the wear is serious, which reduces its life. Therefore, it has become a development trend at home...

AI Technical Summary

Problems solved by technology

However, the brazing temperature of this process is higher than 650°C. Excessively high welding temperatures cause the copper commutator blades to soften severely after the welding cycle, reducing the performance of the graphite-copper composite structure commutator; another method is First obtain a certain thickness of metal coating on the graphite surface, and then use cementation or welding to realize the brazing connection between the metal coating and the copper reversing blade, such as the open literature of Chinese Patent No. ZL03239176.5, this method is used on heat exchangers. The welding cycle temperature experienced by the copper commutator vane is low, and the softening problem is solved. However, because the connection between the metal coating and the graphite substrate is a physical combination, its bonding strength is not high, and graphite and graphite often occur during the service of the commutator. Copper reversing blades fall off, which affects product quality