RU2062157C1 - Method of bending multielbow products - Google Patents

Abstract

FIELD: metal pressure forming, namely tube bending by expansion. SUBSTANCE: method comprises steps of filling a rectilinear tubular blank by gas or liquid, subjecting it to expansion according to a shaping cavity of half-dies. A mathematical relation is given for determining a diameter of the blank for expanding in dependance upon an effective cross section area of the multielbow product, inner radius of its bending, embracing angle of one elbow and admissible percentage elongation of a material of the blank. EFFECT: enhanced efficiency of the method. 2 cl, 5 dwg

Description

 The invention relates to the field of production of multi-knee products by bending pipe billets by internal pressure and can be used in various engineering industries.

A known method of manufacturing steeply curved products, in which the tubular billet is subjected to bending and distribution of pressure from the inside [1]
The disadvantages of this method are the high complexity, high energy consumption and the inability to implement multi-generation bending of products.

A known method of bending multi-knee products, based on the fact that the pipe is subjected to bending in the forming cavity of two closable semi-matrices when creating pressure in the pipe from the inside [2]
The technical result achieved by using the described invention is to expand technological capabilities in the manufacture of multi-knee steeply curved products and to reduce their cost.

This is ensured by the fact that in the method of bending multi-knee products, in which a straight pipe billet is filled with liquid or gas under pressure and subjected to bending it along the shape-forming cavity of the alternating curvature of two closable half-matrices, it is proposed to bend the pipe billet by distributing it with pressure from the liquid or gas side the forming surface of pre-closed semi-matrices, while the diameter d of the tube stock, depending on the diameter of the cross-section of the product D follows Niemann according to the relationship (at the inner radius R and the bending angle of the knee coverage articles β)
d = (D + 2R) • cos β / 2-2R, / 2
and the temperature-time and power regime of its distribution should be established from the condition that the distribution coefficient D / d is 5 10% lower than d _max- limiting relative elongation of the material of the tube billet at the established mode of its distribution, i.e.

Еще больший эффект обеспечивается при использовании этого способа гибки многоколенных изделий, когда раздачу материала трубной заготовки осуществляют в режиме сверхпластического формообразования с использованием внутреннего давления, например, со стороны аргона.

An even greater effect is achieved when using this method of bending multi-knee products, when the distribution of the tube billet material is carried out in the superplastic forming mode using internal pressure, for example, from the argon side.

 The invention is illustrated graphically, where in FIG. 1 shows a cross section of a device with a tube stock; in FIG. 2 is a cross-section of a device with a multi-generation product; in FIG. 3 section of the device along A-A; in FIG. 4 section of the device according to B-B; in FIG. 5 shows the geometric parameters of a section of a steeply curved product.

 A device for implementing the proposed method includes the following. The lower casing 2 is mounted on the table 1, in which the lower half-matrix 5 is fixed with bolts 3 and bolts 4. The upper half-matrix 8 is fixed with bolts 3 and the upper half-matrix 8 is fixed with bolts 7, the half-matrices 5 and 8 forming a wavy cavity 9 alternating curvature. A plug 11 and a fitting 12 (if necessary with an o-ring) are inserted into the end sections of the tube billet 10, respectively. Formed by pressure of a liquid or gas 13, the multi-knee product is assigned position 14.

 The method of bending multi-knee products is as follows.

 A tube stock 10 is installed on the lower half-matrix 5 and the housing 2, the stopper 11 and the fitting 12 are inserted into the end sections of the tube, and then the lower part of the device is fastened to the upper part using bolts 4. The upper part of the device consists of a housing 6, half-matrix 8 and bolts 7. The flanges of the plug 11 and the fitting 12 make it possible to fix the last in the corresponding annular grooves of the upper and lower bodies 6 and 2.

 Next, they provide preliminary closure of the upper and lower parts of the device along the plane of the connector 15 and through the hole 16 of the nozzle 12, liquid or gas 13 is supplied into the pipe billet 10 under pressure, as a result of which the pipe 10 bends along the forming surface 9 of the half-matrices 8 and 5, getting the shape multiple products 14.

 After that, the bolts 4 are unscrewed and the body 6 with the upper half-matrix 8 is removed from the bottom of the device, and the multi-knee product 14 together with the plug 11 and the nozzle 12 are removed from the device, then the plug 11 and the nozzle 12 are removed from the finished product 14. If necessary, the multi-knob pipe 14 is transmitted for cutting in the mating zones of the adjacent knee sections of the obtained product 14, i.e. along the planes 00 'and 0'0' 'of the spatial angle "β" (Fig. 5).

Thus, multi-generation pipe products with a diameter of D with a bending radius R _g and a bending angle of one bend “β” are obtained from a pipe billet with a diameter of d.

Имея сведения по максимальному относительному удлинению штампуемого материала δ_max или определив его значения путем технологических испытаний на относительное удлинение δ_max при различных режимах штамповки, можно для гибки многоколенных изделий установить такой температурно-временной и силовой режим раздачи материала (температуру, время и давление раздачи), для которого снижение δ_max не менее 5 10% обеспечит изготовление многоколенных изделий с коэффициентом раздачи D/d без их разрушения. Это условие записывается в виде следующей зависимости:

Очевидно, что при значении коэффициента раздачи

возможно разрушение штампуемого материала из-за неравнотолщинности его, отклонения фактического режима раздачи от заданного и т.п. Экономически выгодно назначать режимы гибки многоколенных изделий при коэффициентах раздачи D/d, близких к (0,90 0,95)δ_max, так как в противном случае процесс гибки придется осуществлять при больших энергозатратах из-за больших температурно-временных режимов формообразования изделий.Having the values of D as the initial parameters of the multi-knee product, the bending radius R _g and the angle of coverage b according to FIG. 5, it is possible to determine the diameter of the tube billet d for bending a multi-knee product:

Having information on the maximum relative elongation of the stamped material δ _max or determining its values by means of technological tests for the relative elongation δ _max under various stamping modes, it is possible to set such temperature-time and power distribution modes of the material for bending multi-knee products (temperature, time and pressure of distribution) for which a decrease in δ _{max of} not less than 5 10% will ensure the manufacture of multi-generation products with a distribution coefficient D / d without their destruction. This condition is written as the following dependency:

Obviously, with the distribution coefficient

destruction of the stamped material is possible due to its unequal thickness, deviation of the actual distribution mode from the set, etc. It is economically feasible to assign bending modes for multi-generation products with distribution coefficients D / d close to (0.90 0.95) δ _max , since otherwise the bending process will have to be carried out at high energy costs due to the large temperature-time modes of product formation.

 Obviously, the greatest technological capabilities of the method for bending multi-knee products under consideration take place in the case of the distribution of the tube billet in the superplastic forming mode, for example, by internal pressure, for example, from the argon side.

При этом коэффициент раздачи изделия D/d 120/48=2,5.Consider an example of a method for bending a multi-knee product at D 120 mm, β 1000 ^o and R _g 40 mm for a material in the superplastic forming mode. The diameter of the tube stock is set according to the formula (1):

Moreover, the coefficient of distribution of the product D / d 120/48 = 2.5.

Due to the fact that the maximum relative elongation of this material is δ _max 3, and also taking into account the numerical value of the dependence (2), according to which 2.5 <(0.90 0.95) • 3, the shaping of a multi-knee product as described in superplasticity mode is provided.

 The described method of bending multi-knee products can be used both for the manufacture of steeply bent knees, obtained by cutting the obtained multi-knee products into separate knees in the mating zones of their adjacent sections, and for the manufacture of steeply bent special-purpose coils. YYY2 YYY4

Claims (2)

1. The method of bending multi-knee products, in which a straight pipe billet is filled with liquid or gas and subjected to its distribution in the forming cavity of alternating curvature of two closable semi-matrices, characterized in that the diameter of the pipe billet for its distribution is taken according to the dependence
d = (D + 2R _g ) • cos β / 2-2R,
and from the condition that the distribution coefficient D / d is associated with the ultimate elongation of the workpiece at the established mode of distribution of the pipe workpiece by the ratio

where D is the cross-sectional diameter of the manufactured multi-piece product, mm;
d the diameter of the straight pipe billet, mm;
R _{g the} inner radius of the bend of a multi-piece product, mm;
β angle of one knee of the product, rad;
d _max - ultimate relative elongation of the material of the tubular billet.  2. The method according to claim 1, characterized in that the distribution of the tube billet material is carried out in a superplastic forming mode using internal pressure, for example, from the argon side.

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