RU2536849C1 - Method of producing bimetal multiple ply rod and wire articles - Google Patents

Abstract

FIELD: process engineering.

SUBSTANCE: invention relates to metal forming and can be used for production of bimetal multiple ply rod and wore articles. Proposed method comprises forming hook on article with sharpened and conical sections and drawing through tapered channel of monolithic drawing die. Drawing die working channel generatrix inclination to drawing axis is specified by mathematical relationship with allowance for factors including the material outer layer resistance to deformation, holdback tension strain, cross-section area ratio of layers.

EFFECT: lower drawing tension, power saving.

Description

The invention relates to the processing of metals by pressure and is intended for the production of polymetallic multilayer bar and wire products by drawing.

It is known that the rods and wire are made according to the technological scheme, combining the rolling or pressing of the workpiece with the subsequent drawing of a polymetallic multilayer workpiece through conical dies.

When deforming a workpiece in a drawing tool, a drawing stress arises, which can lead to a break in the front end of the workpiece (see Perlin I.L., Yermanok M.Z. Drawing Theory. - M.: Metallurgy, 1971. - p.17).

The closest method of the same purpose to the claimed invention in terms of features is the method of drawing products (see RF patent No. 2310533 dated 11/20/2007, class B21C 1/00), including the preliminary formation of the gripper with pointed and conical sections and subsequent drawing through the working monolithic die channel. Use a die, the angle of inclination of the generatrix of the working channel which is

$${\alpha }_{\mathrm{at}}=arctg(\mathrm{one},414\sqrt{\ln \lambda \cdot f}),(\mathrm{one})$$

- вытяжка при волочении; d₀, d₁ - внешний диаметр прутка или проволоки до и после деформации соответственно; f - коэффициент внешнего трения в очаге деформации при волочении. Данный способ принят в качестве прототипа.Where $$\lambda =d_0^2/d_{\mathrm{one}}^2$$

- hood when drawing; d ₀ , d ₁ - the outer diameter of the rod or wire before and after deformation, respectively; f is the coefficient of external friction in the deformation zone during drawing. This method is adopted as a prototype.

Signs of the prototype, which coincides with the features of the proposed solution, is the preliminary formation on the product grips with pointed and conical sections and subsequent drawing through the working channel of a monolithic die.

The disadvantage of this method, adopted as a prototype, is that the drawing process has increased voltage and energy intensity. This is because the method does not provide the minimum value of the drawing voltage and leads to increased energy intensity of the drawing process. In addition, the known method does not take into account the influence of the geometric ratios of the polymetal layers and their mechanical properties on the voltage, since depending on the geometric ratios of the polymetal layers and their mechanical properties, the drawing voltage will be different.

The objective of the invention is to reduce the drawing voltage and energy consumption of the process of drawing polymetallic multilayer bar and wire products, increase single compressions and the quality of stretched polymetallic multilayer products by optimizing the angle of inclination of the generatrix of the working channel of the drawing tool.

The problem was solved due to the fact that in the known method, including the preliminary formation on the product grips with pointed and conical sections and subsequent drawing through the working channel of a monolithic die, use a die, the angle of inclination of the generatrix of the working channel to the axis of drawing which is

$${\alpha }_{\mathrm{at}}^{\mathrm{about}Pt}=arctg\mathrm{one},41\sqrt{\frac{f\ln \lambda \cdot ({\sigma }_{sn}-{\sigma }_0)\cdot \overline{F_n}}{{\displaystyle \sum _{i=\mathrm{one}}^n{\sigma }_{si}\cdot \overline{F_i}}}},(2)$$

where f is the coefficient of external friction between the die and the outer surface of the workpiece;

λ = F ₀ / F ₁ - drawing during drawing;

F ₀ and F ₁ - the cross-sectional area of the workpiece before and after the passage, respectively;

σ _sn is the deformation resistance of the material of the outer layer;

σ ₀ - stress tension;

- относительная площадь наружного слоя заготовки; $$\overline{F_n}=F_n/F_{\mathrm{one}}$$

- the relative area of the outer layer of the workpiece;

F _n is the cross-sectional area of the outer layer of the workpiece;

σ _si is the deformation resistance of the material of the i-th layer of the workpiece;

- относительная площадь сечения i-того слоя заготовки; $$\overline{F_i}=F_i/F_{\mathrm{one}}$$

- the relative cross-sectional area of the i-th layer of the workpiece;

F _i - sectional area of the i-th layer of the workpiece.

The features of the proposed method, distinctive from the prototype, use a drag, the angle of inclination of the generatrix of the working channel to the axis of drawing which is determined by the above formula 2.

In most cases of drawing polymetallic multilayer billets, there is no forced drag (σ ₀ = 0), therefore, formula (2) takes the form

$${\alpha }_{\mathrm{at}}=arctg\mathrm{one},414\sqrt{\frac{f\ln \lambda \cdot {\sigma }_{sn}\overline{F_n}}{{\displaystyle \sum _{i=\mathrm{one}}^n{\sigma }_{si}\cdot \overline{F_i}}}}.(3)$$

In real drawing conditions, the drawing voltage of a multimetal multilayer billet is determined by the formula (see. Mechanics of composite materials and structures. 2010 - Volume 18, No. 2. S.-267-272)

$${\sigma }_{\mathrm{at}\mathrm{about}l}=(\ln \lambda +\frac{\mathrm{four}}{3\sqrt{3}}tg{\alpha }_{\mathrm{at}})\left[{\displaystyle \sum _{i=\mathrm{one}}^n{\sigma }_{si}\overline{F_i}}+fctg{\alpha }_P({\sigma }_{sn}-{\sigma }_0)\overline{F_n}\right]+{\sigma }_0,(\mathrm{four})$$

where σ _si is the deformation resistance of the material of the i-th layer of the workpiece;

σ _sn is the deformation resistance of the material of the outer layer;

- относительная площадь сечения i-того слоя заготовки; $$\overline{F_i}=F_i/F_{\mathrm{one}}$$

- the relative cross-sectional area of the i-th layer of the workpiece;

- относительная площадь наружного слоя заготовки; $$\overline{F_n}=F_n/F_{\mathrm{one}}$$

- the relative area of the outer layer of the workpiece;

λ = F ₀ / F ₁ - drawing during drawing;

F ₀ and F ₁ - the cross-sectional area of the workpiece before and after the passage, respectively;

α _in - the angle of inclination of the generatrix of the tool to the axis of the drawing;

α _P - reduced die angle tgα _П = 0,65tgα _в ; f is the coefficient of external friction between the die and the outer surface of the workpiece;

Σ is the summation sign;

σ ₀ - stress tension.

The minimum value of the drawing voltage and, accordingly, the drawing force of the polymetallic multilayer workpiece, as well as the energy intensity of the process, is ensured from the condition that the derivative of the drawing voltage with respect to the tangent of the inclination angle of the generatrix of the working channel of the drawing tool is equal to zero, namely

$$\frac{d{\sigma }_{\mathrm{at}\mathrm{about}l}}{d(tg{\alpha }_{\mathrm{at}})}=0(5)$$

Differentiating expression (4) according to condition (5), after transformations, we obtain the equation for determining the optimal value of tgα _in

$$tg{\alpha }_{\mathrm{at}}=\mathrm{one},41\sqrt{\frac{f\ln \lambda \cdot ({\sigma }_{sn}-{\sigma }_0)\cdot \overline{F_n}}{{\displaystyle \sum _{i=\mathrm{one}}^n{\sigma }_{si}\cdot \overline{F_i}}}},(6)$$

and correspondingly

$${\alpha }_{\mathrm{at}}^{\mathrm{about}Pt}=arctg\mathrm{one},41\sqrt{\frac{f\ln \lambda \cdot ({\sigma }_{sn}-{\sigma }_0)\cdot \overline{F_n}}{{\displaystyle \sum _{i=\mathrm{one}}^n{\sigma }_{si}\cdot \overline{F_i}}}}.(7)$$

Relation (7) provides the minimum value of the drawing voltage and the minimum energy consumption of the process of drawing a polymetallic multilayer workpiece.

In the absence of counter-tension (σ ₀ = 0) from formula (6) we obtain the optimal angle of inclination of the generatrix of the working inclination of the die

$${\alpha }_{\mathrm{at}}^{\mathrm{about}Pt}=arctg\mathrm{one},41\sqrt{\frac{f\ln \lambda \cdot {\sigma }_{sn}\cdot \overline{F_n}}{{\displaystyle \sum _{i=\mathrm{one}}^n{\sigma }_{si}\cdot \overline{F_i}}}}.(8)$$

An example of a specific implementation of the proposed method.

; $$\overline{F_n}=\overline{F_1}*i(i=1\dots n)$$

, σ_si=σ_si-2=310 МПа; σ_sn-1=250 МПа. При волочении заготовки через волочильный инструмент с α_в=10° без противонатяжения и вытяжки λ=1,15 при коэффициенте трения f=0,1 среднее напряжение полиметаллической заготовки волочения составило 117 МПа.The proposed method is used for drawing a polymetallic billet of a low-temperature superconductor, consisting of a copper core, intermediate layers of superconducting niobium and a copper stabilizing shell. In this case, the geometric and physical relationships were: $$\overline{F_{\mathrm{one}}}=0,\mathrm{one}$$

; $$\overline{F_n}=\overline{F_{\mathrm{one}}}*i(i=\mathrm{one}...n)$$

, σ _si = σ _si-2 = 310 MPa; σ _sn-1 = 250 MPa. When drawing a workpiece through a drawing tool with α _at = 10 ° without anti-tension and drawing λ = 1.15 with a friction coefficient f = 0.1, the average voltage of the polymetallic drawing workpiece was 117 MPa.

. После изготовления инструмента с оптимальной конусностью провели волочение заготовки с прежними технологическими параметрами, среднее напряжение волочения при этом оказалось равным 97 МПа.By the formula (2) of the proposed method, the optimal taper angle of the drawing tool was determined, and $${\alpha }_{\mathrm{at}}^{\mathrm{about}Pt}=5,7^{\circ }$$

. After manufacturing the tool with optimal taper, a workpiece was drawn with the same technological parameters, and the average drawing voltage turned out to be 97 MPa.

Thus, the decrease in the average drawing voltage when using the proposed method was 17%.

With a decrease in the drawing voltage, it becomes possible to increase the reductions during drawing and to reduce the multiplicity of drawing routes. Reducing the drawing voltage also reduces the likelihood of breakage of the front end of the workpiece and the destruction of the components of the polymetallic multilayer workpiece, thereby increasing the quality of the drawn products.

Claims (1)

The method of drawing polymetallic multilayer rod and wire products, including pre-forming on the product grips with pointed and conical sections and subsequent drawing through the working channel of a monolithic fiber, characterized in that they use a fiber, the angle of inclination of the generatrix of the working channel to the axis of drawing which is

,
where f is the coefficient of external friction between the die and the outer surface of the workpiece;
λ = F ₀ / F ₁ - drawing during drawing;
F ₀ and F ₁ - the cross-sectional area of the workpiece before and after the passage, respectively;
σ _sn is the deformation resistance of the material of the outer layer;
σ ₀ - stress tension;

- the relative area of the outer layer of the workpiece;
F _n is the cross-sectional area of the outer layer of the workpiece;
σ _si is the deformation resistance of the material of the i-th layer of the workpiece;

- the relative cross-sectional area of the i-th layer of the workpiece;
F _i - sectional area of the i-th layer of the workpiece.