RU2587108C9 - COPPER ALLOY, TelM DOPED WITH TELLURIUM, FOR COLLECTORS OF ELECTRIC MACHINES - Google Patents

Abstract

FIELD: metallurgy.

SUBSTANCE: invention relates to metallurgy, particularly, to copper alloys for collector plates of electric machines. Alloy contains, wt%: tellurium 0.15-0.80, magnesium 0.1-0.6, phosphorus not more than 0.04, impurities of not more than 0.2, copper - the rest.

EFFECT: use of disclosed alloy increases economic efficiency of its production, reduced losses of rejects in production of cold-deformed sections, enables to achieve stable high operational properties of reservoirs.

1 cl, 2 tbl

Description

The invention relates to the field of metallurgy, and in particular to the use of semi-finished products in the form of cold-deformed profiles from copper-based alloys for the manufacture of collector plates of electric machines.

The collector profile is a long strip having a trapezoidal cross-sectional shape, the trapezoid being isosceles and elongated in the direction of height. The main technical and operational properties (strength properties, wear resistance, electrical resistivity, etc.) should be the same for the entire product. This is achieved by uniformity of the chemical composition of the alloy and a stable technology for the production of profiles for collectors of electrical machines.

Existing alloys regulated by GOST 4134-75 (BrKd1) and TU 184480-106-196-2007 (EC) have a number of disadvantages.

So, GOST 4134-75 “Profiles from copper alloys for collectors of electric machines” provides for the production of profiles made of BrKd1 bronze with a chemical composition corresponding to GOST 18175-78 “Tin-free bronze treated by pressure”, which reflects the content of the main components and the total amount of impurities, without regulation of individual impurities. Namely: cadmium 0.9-1.2%, impurities no more than 0.3%, copper - the rest. It is possible to assume that the content, for example, of lead is 0.25%, and the sum of the remaining impurities determined is 0.04%. With such a lead content, the machinability of copper-based alloys (bronzes) is significantly deteriorated, the production technology becomes unstable, achieving the required mechanical properties is problematic. The EC alloy is also known, from which profiles for collectors of electric machines are made [RF patent No. 2291910]. The composition of the alloy includes: tin - 0.1 to 0.24 wt. %, silver - 0.02-0.08 wt. %, phosphorus - up to 0.015 wt. %, impurities - up to 0.2 wt. %, copper - the rest. A narrow range of the content of the main elements in the EC alloy reduces the stability of the process for producing cast billets (ingots). Melting units equipped with an induction channel furnace of the ILK type of various useful capacities and an induction channel mixer ILKM are mainly used to obtain ingots from EC alloy. Obtaining a uniform (homogeneous) chemical composition of the melt in two melting tanks is difficult, which increases the percentage of defective chemical composition, thereby increasing the cost of production.

It is clear that consumers are interested in the fact that each product used in assembling the collector of an electric machine has the same technical characteristics. And manufacturers of collector profiles are interested in material and manufacturing technology that will achieve the required technical characteristics, quality indicators and the economic feasibility of producing this product.

The closest to the proposed technical essence and the achieved result is a copper alloy doped with tellurium [see European standard DIN EN 12164-1998 “Copper and copper alloys. Bars with good machinability "or http://www.trm.by/index.php/ru/prutki-iz-splava-med-tellur" Copper-tellurium alloy bars "], having the following chemical composition:

- tellurium - 0.4-0.7 wt. %;

- phosphorus - 0.003-0.012 wt. %;

- aluminum - not more than 0.02 wt. %

This alloy is well processed by cutting, but gives a lot of rejects during processing by cold deformation and stamping. In addition, it does not fully meet the entire set of requirements for alloys for collectors of electric machines.

The technical result of the present invention is to create a tellurium-doped copper alloy for collectors of electric machines having high repeatability (long-term stability) of the required properties from batch to batch, reducing the cost of the collector profile from the proposed alloy by reducing waste from scrap, and also increasing the durability of the collectors electrical machines made from this profile.

These results are achieved by the fact that the proposed tellurium alloyed copper alloy for the collectors of electric machines has the chemical composition shown in table 1.

The composition of the proposed alloy eliminates the disadvantages of standard alloys: BrKd1, BrMg0.3 EK and DIN EN 12164-1998.

Doping of copper with tellurium allows to achieve a significant improvement in machinability by cutting (90% of the machinability of lead brass), while the mechanical and physical properties remain close to the properties of pure copper. Hard and soft soldering of the proposed alloy is not difficult. Tellurium has a positive effect on the thermal stability of the main component - copper. Thus, the strength of the alloy with a Te content of 0.6% in the deformable state does not change at a temperature of 350 ° C for 2 hours, while pure copper under these conditions softens after 10-15 minutes. Due to the presence of solid dispersed inclusions of copper telluride in a soft copper matrix, the Cu-Te system alloy has good antifriction properties in combination with high thermal conductivity. The electrical conductivity of copper doped with tellurium and magnesium when they are kept within the stated limits has a guaranteed value of σ = 55 MSm / m (ρ = 0.0182 · 10 ⁶ , Ohm · m). An increase in tellurium content in excess of 0.8% increases the cost of the alloy without further significant improvement in machinability. At a content below 0.15%, the machinability of the alloy deteriorates and becomes almost the same as that of pure copper.

The presence of magnesium in the alloy allows you to achieve the required hardness values (not less than 95 HB). Reducing the viscosity of the alloy, alloying with magnesium additionally reduces marriage during drawing and stamping. Based on the analysis of scientific and technical information and the results of experimental research, the most rational range of magnesium content in the alloy is 0.1-0.6%.

Although alloying copper with magnesium simultaneously deoxidizes it, the proposed alloy does not suggest the use of magnesium for deoxidation, since the oxygen content in the initial copper varies widely, and this makes it difficult to accurately maintain the magnesium content in the final product. In the preparation of the proposed alloy, it is deoxidized with phosphorus, forming vaporous and liquid deoxidation products (P ₂ O ₅ CuPO ₃ ). This makes it possible to stabilize the magnesium content in the alloy, make it independent of the oxygen content in the initial copper, and thereby reduce the chemical composition defect. That is, to reduce the cost, ultimately, production. Since the excess phosphorus remaining in copper reduces the thermal and electrical conductivity, its content should be minimal, but at the same time sufficient for guaranteed and complete deoxidation of the melt. Experimental research established the upper limit of the permissible rational phosphorus content in the alloy to not more than 0.04% and developed a specific procedure for the preparation of the melt, where the alloying operation with magnesium is carried out after the melt has been deoxidized with phosphorus. This limit is higher than in the prototype, which reduces losses from defects in chemical composition. Experience has shown that, to the stated limit, the practical properties of the alloy do not deteriorate.

The claimed technical results are achieved when the above conditions are met for the maximum content of normalized impurities, the total content of which should not exceed 0.07%. Impurities of other elements do not significantly affect the properties of the alloy and, therefore, their content is not element-wise standardized, provided that the total content of normalized and non-normalized impurities does not exceed 0.2%. Exceeding the declared content for each of the normalized impurities reduces the mechanical and electrical characteristics of the alloy and profile. Fulfillment of the declared restrictions on the content of impurities does not increase the cost of the product, since the starting materials usually have the necessary purity. It is just that during the initial inspection of the starting materials it is required to pay attention to the fact that the total content of each of the impurities in all materials does not exceed the declared one.

Other properties of the proposed alloy are presented in Table 2.

The technological scheme for the production of cold-formed profiles from the proposed alloy. The dimensions of the ingots and the profile are shown as an example.

1. Obtaining cast billets (ingots) ⌀ 175 mm.

1.1 Obtaining melt in furnaces such as ILK or ILT.

1.2 Casting ingots ⌀ 175 mm in a semi-continuous method, (casting temperature 1170-1200 ° C).

1.3 Cutting of ingots into dimensional blanks measuring 175 × 350 mm using band saws or disk machines and with the selection of templates for determining macro-density (quality control of the density of ingots).

2. Production of collector profiles 2.17 × 3.58 × 78 mm.

2.1 Heating a cast billet with a size of 175 × 350 mm in a gas heating furnace to a temperature of 830-870 ° C.

2.2 Pressing the workpiece using a horizontal hydraulic press with a force of 15 MN. The size of the obtained pressed billet is 5.0 × 8.2 × 80 mm.

2.3 1st drawing of the pressed billet to a size of 3.9 × 6.4 × 79.5 mm on a chain drawing mill with a force of 200 kN.

2.4 Annealing the workpiece at a temperature of 680 ° C for 90 min in a light annealing furnace (the atmosphere in the furnace is exogas).

2.5 2nd drawing to the finished product size of 3.0 × 550 × 78.5 mm on a chain drawing mill with a force of 200 kN.

2.6 Annealing the workpiece at a temperature of 680 ° C for 90 min in a light annealing furnace (the atmosphere in the furnace is exogas).

2.7 3rd drawing to the size of the finished product 2.17 × 3.58 × 78 mm on a chain drawing mill with a force of 200 kN.

2.8 Testing of mechanical properties and verification of quality indicators.

The proposed alloy is high-tech in pressure processing, welding and soldering. The characteristics of cold-deformed profiles made from it - strength properties, heat resistance, the absence of hydrogen disease, heat and electrical conductivity, fully ensure compliance with the requirements for collectors of electric machines. Using the proposed alloy and the above-described technology for manufacturing a cold-deformed profile from it practically nullifies the percentage of rejects, both in terms of the properties of the ingots and in defects in the finished profile. Studies of selected templates showed a high uniformity of the mechanical properties of the alloy, both within the ingot and from ingot to ingot. The stability of the technical and operational properties of the alloy is confirmed by the test results.

Claims (2)

1. Tellurium-doped copper alloy for collectors of electrical machines, characterized in that it contains components in the following ratio, wt.%:
tellurium 0.15-0.80 magnesium 0.1-0.6 phosphorus no more than 0,04 impurities no more than 0.2 copper rest 2. The alloy according to claim 1, characterized in that it contains the following impurities, wt.%:
lead no more than 0,01 iron no more than 0,02 zinc no more than 0,01 nickel no more than 0,01 silicon no more than 0,02
.