SU871890A1 - Horn-like core - Google Patents

Description

(54) HORSE-BORN CORE

one

The invention relates to machine building, namely, to the production of steeply bent bends from tubular billets of stainless and heat resistant steels used as parts of pipelines and apparatuses of chemical, energy and other industries.

A horn-shaped core for the manufacture of steep-bend branches, comprising a shaping section and an internal longitudinal cavity for supplying liquid 1, is known.

The insufficient rigidity of the known core is due, firstly, to the high stresses that occur in the formative part of the core, and secondly, because of the decrease in the strength of the core metal at operating temperatures (1000-1100 ° C). The flow of fluid into the internal cavity of the core is ineffective in the manufacture of heat-resistant or thick-walled taps for the following reasons. When pushing tubular blanks, tensile stresses arise in this core, on which additional stresses are applied to the forming section, caused by

moment of forces, extensor core. In this case, the most dangerous place is the surface layer located on the side of the greater curvature of the shape-changing part of the core. Therefore, cooling the core in the central axial part, where the stresses do not reach the maximum value, is ineffective.

A horn-shaped core for the manufacture of steep-curved bends is known, comprising a shaping section and an internal longitudinal cavity for supplying fluid, which is eccentrically in the direction of the greater curvature of the core. This core solves the problem of increasing the stiffness of the core 2.

Claims (2)

The disadvantage of it is that it does not define the value of eccentricity, which can cause a significant temperature difference between different places on the surface of the core. However, from the working conditions it is necessary that the temperature difference between different places on the core surface does not exceed 100 ° C. The large difference causes the formation of corrugations and other defects of the taps due to the uneven cooling of the tube stock passing through the core. The purpose of the invention is to improve the quality of the produced taps. To achieve this goal, in a horn-shaped core for the manufacture of steep-curved bends, containing a shaping section and an internal longitudinal cavity for supplying fluid, which is eccentric in the direction of the greater curvature of the core, the eccentricity E is E (0.1-0.2) g, a, g Go + ms, where Ha is the radius of the core at the beginning of the forming section; gp - the coefficient of taper of the core; S is the length along the axis of the core from the beginning of the forming section to the corresponding section. FIG. Figure 1 shows the proposed core with conventional diagrams of stresses in the longitudinal and transverse sections of the rectilinear (A and B) and shape-changing (C, D, D) sections of the core, a general view; in fig. 2 - core (cut), general view. It was established experimentally that reducing E by 0.1 g reduces the positive effect, since in this case the cooling of the most stressed surface layer relative to the others does not exceed 30–50 ° C, which does not give a greater gain in the strength of steel. So the mentioned ILS-2 steel at 1000 ° С has a short-term strength of 14 kg / mm2, and at 970 ° С - 16.5 kg / mm2. An increase in E above 0.2 g leads to a relative supercooling of the surface of more than 100 ° C, which causes the above-mentioned technological defects of the product. Thus, the displacement of the axis of the cooling hole relative to the axis of the core is equal to (0.1-0.2) g, taken from the condition that the temperature difference between the different surfaces of the forming part of the core is within 50-100 ° C, and therefore its durability increases. Example. The industrial core has the following parameters: D 122: Ri 240, Rs 310, do 82, d, 95, Ar 107, dj 117, m 0.15. The axis of the cooling hole relative to the center axis of the core is determined by the EC 4–8 mm at the beginning of the shaping region, and EI 4.7– 9.8; Ег 5,3-10,6 and Ез 5,85-11,7, respectively, in the sections di, d2, da equals. Cooling the dangerous layer of the forming part of this core on average 80-90 ° С from 1000 ° С provides an increase in the strength of IZhS-2 steel by 21 / o, which increases the resistance of the core by 2-3 times. Taking into account the cost of the alloy, the effect of enhancing the durability of one core size is 750-1500 rubles / piece. Claims of the invention: A torn-shaped core for the manufacture of steep-bend branches, comprising a shaping section and an internal longitudinal cavity for supplying fluid, which is eccentric in the direction of the greater curvature of the core, characterized in that, in order to increase the quality of the produced branches, the eccentricity E is E (0.1 0.2) g, ag Go + ms, where Go is the radius of the core at the beginning of the forming section; m is the coefficient of the taper of the core; S is the length along the axis of the core from the beginning of the forming section to the corresponding section. Sources of information taken into account in the examination. 1. USSR author's certificate No. 584931, cl. B 21 D 9/12, 1976. 2. USSR author's certificate number 564906, cl. B 21 D 9/12, 1974.