SU1738410A1 - Composite blank for extruding bimetallic rods - Google Patents

Abstract

Usage: in metal forming for pressing bimetallic products of circular cross section. The essence of the invention: the preform consists of a core and a shell arranged concentrically and without a gap. The core is made with a conical section on the side of its working end and with a central conical cavity, the base diameter of which is 0.8-1.0 core diameter, the taper angle of the conical section is 5-20 °, and its larger base is located at a distance of 0.05-0.5 diameter of the core. On the inner surface of the shell there is a conical section, the larger base of which is located at the same distance with the large base of the conical section of the core. The angle of the cone of the core is equal to the angle of the cone of the shell. The presence of a conical cavity at the working end of the workpiece contributes to a uniform flow of the metal during pressing due to the equalization of the outflow speeds of the core and the shell, which increases the yield. 1 il. sl C

Description

The invention relates to the processing of metals by pressure, in particular, to the construction of a composite billet used to obtain by extrusion bimetallic rods of circular cross section.

A known composite preform for pressing bimetallic products, consisting of concentric parts of the base and cladding metals.

The disadvantage of this blank is the inevitability of waste of the part of the cladding metal, since with these ratios of the lengths of the parts of the cladding and base metal of the original blank, a significant part of the metal of the cladding layer remains in the press balance.

Also known is a composite blank for pressing bimetallic products consisting of concentric parts of the base and cladding layer, with a part of the base metal over the length of the workpiece, 0.1-0.5 times the circumference of the circle, describing the cross-section profile of the workpiece. the perimeter of this part, having a width corresponding to the thickness of the part of the cladding metal, while the part of the cladding metal is made shorter than the part of the base metal by the length of the step.

The disadvantage of this invention is the uneven distribution of the cladding layer on the front end.

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rod, which leads to a decrease in yield.

Closest to the proposed technical solution to the technical essence and the achieved result is a multilayer billet, made in the form of a shell and placed in it with a gap of the core with a tapered pointed end, and the shell is made with a pointed end, the angle of which is less than the angle of the cone of the core.

A disadvantage of the known solution is also the uneven distribution of the cladding material of the sheath and, as a consequence, a decrease in the yield.

The purpose of the invention is to increase the yield due to the uniform distribution of the cladding material of the workpiece from its working end.

In comparison with the known invention, the increase in yield will be 2-3% due to the exclusion of the end trim.

Placing the shell and core layers without a gap helps to improve the quality of welding of the cladding and base materials, as well as uniform distribution of the cladding layer along the entire length of the extruded rod.

Execution on the core from the side of the conical section of the central conical cavity helps leveling the flow rates of the central and peripheral layers of the workpiece, which ensures uniformity at the front end of the extruded rod, which allows increasing the yield by reducing the front cut-off.

The diameter of the base of the cone cavity cannot be larger than the diameter of the core, since the circumference of this diameter is formed by the intersection of the surface of the cone and the cylinder bounding the surface of the core. When the diameter of the base of the conical cavity is less than 0.8 of the core diameter, an area of the bare support layer is formed on the front end of the pressed bar, which reduces the yield of the final product.

When the base of the tapered portion of the outer surface of the core from its working end is located at a distance less than 0.05 of the diameter, an excessive thinning of the cladding layer on the front end of the rod is observed. At a distance greater than 0.5 of the core diameter, the length of the non-stationary section increases, which reduces the yield of the final product.

When choosing the angle of conicity of the conical section less than 5 °, the metal does not flow evenly, which leads to

excessive thinning of the cladding layer and its thickness in the finished bar is less than the average layer thickness in the stationary section. When choosing a taper angle more

5 to 20 °, the outflow speeds of the peripheral and central layers of the workpiece do not equalize and an excessive increase in the thickness of the cladding layer is observed. The thickness of the cladding layer in the extruded rod at the front end will be greater than the cladding thickness of the stationary portion.

The execution of the conical section of the shell on its inner surface, more

5, the base of which is located at the same distance with a large base of the conical section of the core and the angle of taper equal to the angle of the cone of the core, helps leveling the thickness of the cladding layer at the initial moment of pressing, which ensures its uniform distribution along the entire length of the extruded rod. The drawing shows a composite billet for pressing bimetallic

5 bars, axial section.

The composite billet consists of layers of shell 1 and core 2, which are concentrically placed without a gap. On the outer surface core 2 is provided with a conical section 3, the base of which from its working end is located at a distance (H) 0.05-0.5 of the core diameter The angle of conicity of the cone section 3 is 5-20 °. On the core 2, from the side of the conical section, the central conical cavity 4 is made, the base diameter (Dn) of which is 0.8-1.0 of the diameter of the core 2. The shell 1 on the inner surface is provided with a conical section 5, larger

0 the base of which is located at the same distance with the large base of the conical section of the core 2, and the angle of the shell is equal to the angle of the cone of the core.

During pressing, the blank is placed into the container in such a way that the central conical cavity 4 faces the die (not shown). After pressing the ram onto the workpiece, the materials of the core and the shell fill the conical cavity of the die, after which the joint outflow of materials begins through the die gage.

The presence of a central conical cavity

5 at the end of the workpiece contributes to the uniform flow of the metal, since the rates of outflow of the core and shell layers are equalized.

To verify the proposed workpiece, experiments were conducted in which

blanks with boundary, overseas, and average parameter values were used. For comparison, a blank made in accordance with the prototype was also used. Billets used in the manufacture of bimetallic bars silver-copper. The outer diameter of the workpiece was 99 mm. The core is made of copper, and the shell is made of silver. After pressing, the yield was evaluated.

The results of experiments on the effect of the parameters of the shape of the workpiece on the yield of the material during pressing are given in the table.

As can be seen from the table below, when pressing the blanks with dimensions corresponding to the one proposed, the yield increases by reducing the size of the end edge. Pressing blanks with dimensions outside the limits indicated in the claims do not give a positive effect in comparison with the prototype.

Claims (1)

Formula of the Invention Composite billet for pressing bimetallic rods made in the form of concentrically placed layers of the shell and core with tapered sections on the side of their working ends, characterized in that, in order to increase the yield due to uniform distribution of the cladding shell material on the side of its working end the layers are placed without a gap, on the core from the side of the conical section there is a central conical cavity, the base diameter of which is 0.8-1.0 core diameter, the base the conical section of the outer surface of the core is located from its working end at a distance of 0.05-0.50 of its diameter, the angle of conicity of the conical section of the core is 5–20 °, the conical section of the shell is made on its inner surface, the larger base of which is located at one distance with a large base of the conical section of the core, the angle of the shell cone is equal to the angle of the cone of the core. :