RU2090310C1 - Method for semicontinuous pressing of consumable electrode from burden materials of titanium alloys - Google Patents

Abstract

FIELD: powder metallurgy, in particular, manufacture of consumable electrodes from high-reaction metals and alloys used for vacuum arc remelting. SUBSTANCE: method involves controlling pressed series-produced electrode for defects; in case defects are detected on electrode surface, performing pressing of low-weight electrode and introducing 25-50% of cast lump wastes into burden. EFFECT: increased efficiency, simplified construction and enhanced reliability in operation.

Description

 The invention relates to the field of powder metallurgy, in particular to methods for manufacturing extruded consumable electrodes from titanium alloys.

 A known method of semi-continuous pressing of products from charge materials, in which improving the quality of the pressed product is achieved by cleaning the matrix of adhering metal after each pressing through the use of a combined action press (direct and reverse pressing) (see Pavlov V.A. et al. Processing the pressure of non-ferrous metal powders. M. Metallurgy, 1977, p. 81).

 For pressing titanium electrodes with a heterogeneous charge, the reverse pressing method is not possible.

 Closest to the technical nature of the claimed invention is a method of manufacturing a consumable electrode for smelting ingots of high alloy titanium alloys from charge materials of titanium alloys, including filling the charge in batches into a cone matrix, pressing and pushing portions through the matrix in one stroke of the punch (US Pat. RF N 2015845, C. B 22 F 3/20, publ. 1994).

 The disadvantages of this method are the reduced productivity of the pressing process and the formation of various kinds of defects on the surface of the electrode. This is explained by the fact that as the electrodes are pressed, the charge materials stick to the matrix walls (a “shirt” forms). The presence of a “shirt” reduces the pressing speed and degrades the quality of the electrode surface.

 The proposed technical solution is aimed at increasing the productivity of the pressing process by timely removal of adhering metal ("shirt") from the matrix walls.

 The problem is solved in that in a method of manufacturing a consumable electrode from charge materials of titanium alloys, which includes filling charge materials in portions into a cone matrix, pressing and pushing the presses through the matrix in one pass, after detecting surface defects on the pressed electrode, the small-sized electrode is pressed by adding in the charge 25 50% of cast lumpy waste.

The working matrix is heated to 100 200 ^o C in order to obtain the optimal coefficient of friction between the working walls of the matrix and the pressed electrode. The electrode itself consists of 65 95% of titanium sponge, which, grasping during the pressing process with the walls of the matrix, forms a stable “shirt” between the electrode and the walls of the matrix. A “shirt” (sponge titanium adhering to the matrix walls) leads to a deterioration in the surface quality of the manufactured electrodes: transverse cracks and longitudinal strips. After pressing such an electrode, a small weight electrode (1.0 1.5 t) is pressed with the addition of 25 to 50% of cast lump waste, which strips the resulting "shirt" from the matrix walls, cleaning it.

 The practice of pressing electrodes shows that the presence of 25–50% of cast lumpy waste in the electrode is sufficient to remove the “shirt” from the working surface of the matrix. The introduction of lumpy waste into the charge of less than 25% does not remove the “shirt” from the walls of the matrix.

 For effective cleaning of the matrix walls from the “shirt”, it is sufficient to use one electrode with the addition of 25% of lumpy waste to a charge weighing 2 tons. The use of more than 25% of the amount of lumpy waste improves the quality of cleaning the walls of the matrix and at the same time reduces the cost of the electrode, since the cost of lumpy waste is significantly lower than the cost of sponge titanium. But the addition of lumpy waste of more than 50% leads to a decrease in the strength properties of the resulting electrode. It falls apart into separate parts and before melting, these parts are joined by argon-arc welding, which increases the complexity of the operation and reduces productivity. The pressed electrode of small weight is used in further production.

 Example.

 The proposed method was tested in industrial conditions of the press department of the smelting and foundry when pressing consumable electrodes with a diameter of 515 mm titanium alloy W1-0 by weight 3800 kgf and 4300 kgf on a vertical hydraulic press mod. D615OM with a force of 10 thousand tonnes of charge, which includes sponge titanium with the addition of 15% return waste in the form of trimmings and shavings. The weight of one portion of the charge is 125 kg.

 10 electrodes were pressed, and on the subsequent ones visual signs were found characterizing the presence of a “shirt” on the matrix walls: small transverse cracks not only between the individual pressed portions, but also on the surface of the portions; longitudinal wide grooves on the cylindrical surface of the electrode along its entire length. To remove the “shirt”, an electrode weighing 1000 kgf was pressed with the addition of 25% cast lumpy waste to the charge. The adhering metal from the walls of the matrix was removed. Then continued pressing the next batch of serial electrodes. After pressing 10 pieces of electrodes, the presence of a “shirt” was again detected, which was removed by pressing an electrode weighing 1000 kgf with the addition of 50% cast lump waste. The removal of adhering metal by pressing the electrode with the addition of 20% cast lumpy waste into the charge did not lead to a positive result. I had to clean the matrix several times, which reduces the productivity of the process. When the electrode was pressed with 55% cast lump waste added to the charge, the “shirt” was easily removed, but the electrode broke and before melting, some of it had to be joined using argon-arc welding plates.

 The advantage of the proposed method of manufacturing a consumable electrode in comparison with the known ones consists in the timely and high-quality cleaning of the matrix walls of adhering metal by pressing a small-weight electrode, which includes 25 50% cast lumpy waste, which improves the productivity of the electrode manufacturing process, without compromising their quality.

Claims (1)

 A method for semi-continuous pressing of a consumable electrode made of charge materials of titanium alloys, comprising filling the charge in portions into a cone matrix, pressing and pushing the compacts through the matrix in one pass, characterized in that after detecting surface defects on the pressed electrode, the small-sized electrode is pressed by adding 25 to the charge 30% cast lumpy waste.