RU2128566C1 - Method for making ampoule-powder system - Google Patents

Abstract

FIELD: manufacture of constructional members in the form of tubular envelope filled with powder, for example powder wire, heating members and so on. SUBSTANCE: method comprises steps of preliminarily selecting size of tubular blank according to given mathematical formulae including ready member parameters, target density of powder filler and other parameters; filling selected blank by powder; sealing it at both ends and making ready product at deforming blank. EFFECT: lowered material losses, enhanced uniformity of filler. 5 cl, 2 dwg

Description

 The invention relates to a technology for producing structural elements made in the form of an ampoule-powder system (APS), i.e. representing a shell with a powdery filler, and can be used in the manufacture of heating elements, pyrotechnic devices, core elements of nuclear reactors, welding electrodes, electric heaters, thermocouple wires, cored wires and other devices having a similar structure.

 The APS, currently used in industry, has rather stringent requirements in terms of dimensions, filler density, uniformity of filler and shell. Therefore, the methods of manufacturing such structures take into account various factors affecting the yield of products.

 A known method of manufacturing an ampoule-powder system, in particular, the so-called flux-cored wire used as a welding electrode (see L.A. Krasilnikov, A.G. Lysenko, Wire Drawer, M., Metallurgy. 1987, p. 117 - 120).

 The method includes forming a gutter-like profile from a tape with a constant supply of powdery filler-charge inside the gutter and subsequent deformation of the initial workpiece simultaneously with compaction of the powdery filler. The method allows to obtain various profiles of the ampoule-powder system due to drawing in rollers with closed gauges. However, with non-uniform dosage of the powdered filler, its density in the finished product turns out to be variable, which has a negative effect on the parameters of the product.

 In the manufacture of flux-cored wire of small diameter with the most common coefficients of filling the cavity with a charge equal to 40 - 65%, multiple compression (deformation) is performed until the required total compression is obtained (see USSR author's certificate N 1532255, class B 23 K 35/40, 1989). The introduction of a two-stage drawing allows you to get wire from inexpensive non-deficient tapes, but does not guarantee an increase in the yield of suitable products.

 The closest in technical essence to the described is a method of manufacturing an ampoule-powder system, including filling in the original tubular billet of a powdered filler with the required characteristics, sealing the billet and obtaining the finished element with the specified parameters by deforming the billet (see UK application N 138304, class B 23 K 35/40, 1975). The method involves simultaneously with the compaction of the charge the implementation of plastic deformation of the shell, which improves the quality of the products by increasing the uniformity of the physico-mechanical properties of the charge.

 The modes of the deformation process are chosen so as to exclude the formation of defects in the resulting product, which are manifested in ruptures of the shell, heterogeneity of the filler, the formation of sagging on the shell, a change in the thickness of the shell along the length, etc.

 Nevertheless, it is not always possible to provide the required characteristics of the finished product only by changing the modes of the deformation process, which leads to the need to increase the thickness of the initial billet to increase its strength properties in the process of deformation with subsequent additional processing of the external surface (for example, chemical etching) to obtain the specified dimensions of the finished products. At the same time, the sizes of the initial blanks are selected experimentally, achieving an acceptable result, without taking into account their influence on the technology of obtaining APS.

 The objective of the present invention is to provide a method of manufacturing an ampoule-powder system, which is based on the selection of the dimensions of the initial billet, significantly affecting manufacturability in the deformation process.

 As a result of solving this problem, the implementation of a new technical result is achieved, consisting in the reduction of defects during deformation of the workpiece, which allows to reduce the loss of materials, shell, and also significantly increase the uniformity of the powdered filler.

где S_об.э. - площадь сечения оболочки готового элемента;
S_к.э. - площадь сечения порошкообразного наполнителя в готовом элементе;
S_об.о. - площадь поперечного сечения оболочки в заготовке;
S_н.о. - площадь поперечного сечения продольной вставки внутри наполнителя в заготовке;
S_н.э. - площадь поперечного сечения продольной вставки внутри наполнителя в готовом элементе;
N - коэффициент, учитывающий наличие продольной вставки внутри наполнителя; N = 1 при ее наличии, N = 0 при отсутствии;
l_Э - длина готового элемента;

- экспериментально определяемый коэффициент деформационного уплотнения наполнителя;
γ_э - плотность порошкового наполнителя в готовом элементе;
γ_o - плотность порошкового наполнителя в заготовке.The specified technical result is achieved by the fact that in the method of manufacturing an ampoule-powder system, comprising filling the initial preform with a powder filler with the required characteristics, sealing the preform and obtaining the finished element with the given parameters by deforming the preform, the thickness (t _o ) of the shell, the length (l ₀ ) and the outer diameter (D ₀ ) of the initial billet is selected from the relations

where S _r.o. - the cross-sectional area of the shell of the finished element;
S _ke - the cross-sectional area of the powdered filler in the finished element;
S _r.o. - the cross-sectional area of the shell in the workpiece;
S _n.o. - the cross-sectional area of the longitudinal insert inside the filler in the workpiece;
S _AD - the cross-sectional area of the longitudinal insert inside the filler in the finished element;
N is a coefficient taking into account the presence of a longitudinal insert inside the filler; N = 1 in its presence, N = 0 in the absence;
l _e - the length of the finished element;

- experimentally determined coefficient of deformation compaction of the filler;
γ _e is the density of the powder filler in the finished element;
γ _o - the density of the powder filler in the workpiece.

 Symbols of the elements are shown in FIG. 12.

 It is advisable to deform the workpiece with intermediate annealing, the finished product is subjected to final annealing, which improves the structure of the shell material.

 In addition, if the shape of the finished product must be spiral, then this operation can be performed either after deformation of the workpiece, or simultaneously with deformation.

 A distinctive feature of the present invention is that the selection of the dimensions of the initial preform in accordance with the above ratios allows you to get the finished element without further processing with minimal loss of shell material during deformation and taking into account the required structure of the filler.

 The described method is implemented as follows. Depending on the set sizes of the finished product, the dimensions of the workpiece are selected, which are deformed by known methods to obtain APS.

 Example 1

For the manufacture of welding wire of the AN-8 grade in a sheath made of 08KP-OM steel, dimensions: outer diameter (D _e ) 1.6 mm, sheath thickness (te) 0.25 mm and length (le) 120,000 mm with a filler containing rutile concentrate (22.8 wt.%), Fluorspar concentrate (11.0), sodium silicon fluoride (3.2), ferromanganese (7.2), ferrosilicon (4.0), iron powder (the rest), the density of which γ _e = 4.4 g / cm ³ , at N = 0.

From the values of K previously determined experimentally, a coefficient of deformation compaction equal to 1.87 is selected. The geometrical characteristics of the finished element determine the area of the shell and the filler - S _volume = 1,0603 mm ² , S _ke = 0.9503 mm ² . Then, according to the above dependence, the ratio t ₀ / D ₀ = 0.1043 is calculated. In the presence of tube blanks with a diameter of D ₀ = 10 mm, it is necessary to select a workpiece with a wall thickness (t ₀ ) of 1.05 mm, which is more consistent with the calculated value of 1.043 mm.

Next, calculate S _vol.o = 29.523 mm ² , the length of the workpiece l ₀ = 4310 mm and the density of the filler in the workpiece γ _o = 2,353 g / cm ³ .

A tube billet with one end pre-sealed (by any known welding method: electric beam, argon-arc, etc., or by installing an end cap that can be fused or rolled) is filled with filler. Filling is carried out using a funnel feeder on a vibration stand with an oscillation frequency of 50 Hz. When the height of the filler column reaches l _{0, the} backfill is stopped and the second end of the workpiece is sealed.

After that, the workpiece is deformed, for example, by drawing, or by rotary forging, or by any known method to a final diameter of 1.6 mm with one-time deformations per pass of 10-15% or by rolling. In this case, the restoration of the reserve of plasticity of the shell material is carried out due to intermediate annealing at a diameter of 3.5 mm, in a protective, reducing or inert atmosphere at a temperature of 580 - 650 ^o C for 2 to 4 hours.

 Example 2

 The manufacture of a heat-electric heating element (TEN), which is a shell filled with a filler in the form of an electric insulating alumina powder, in which a longitudinal inner insert in the form of a nichrome wire (N = 1) is located, is performed in the following sequence.

Specify the geometric dimensions of the final product - diameter D _e = 8 mm, wall thickness t _e = 0.6 mm and length l _e = 900 mm, as well as the required filler density in the finished product γ _e = 3.31 g / cm ³ .

According to the previously obtained values, summarized in the table, the value K = 1.5 is selected and S _vol. = 13.9487 mm ² , S _ke = 36.102 mm ² , S _BC = 0.19625 mm ² . Then, the ratio t ₀ / D ₀ = 0.05397 is determined.

From the existing assortment of pipes with a diameter of 12 mm, a workpiece with a wall thickness of 0.65 mm is selected, since the exact value of t ₀ is 0.6476 mm. The remaining values are calculated - the necessary length of the workpiece l ₀ = 541 mm and the density of the filler in the workpiece equal to 2.207 g / cm ³ .

Then, the initial tube with a nichrome wire 0.65 mm in diameter previously placed inside it and one sealed end is filled with aluminum oxide on a vibrating stand. Upon reaching a column height of alumina equal to l ₀ , the shaking is stopped and a plug is installed on the second end of the pipe.

 Next, the workpiece is deformed by rolling in a 12-stand roll mill KOR-12 to a final diameter of 8 mm with a total strain of 39%. After deformation, the finished element is twisted into a spiral. Instead of a wire conductive inner insert, a powdered, electrically conductive graphite-containing composition can be used. In this case, the coefficient N is taken equal to zero.

 Example 3

To use the burnable absorber element, made in the form of a spiral from a round wire element, wound round to round with an outer diameter of 7.5 mm and a length of 500 mm with a given filler density of 2.55 g / cm ³ in the form of a mixture of boron carbide absorber in a neutron-transparent matrix from aluminum oxide in a shell of zirconium alloy, by the neutron-physical calculation determine the outer diameter of the finished element D _e = 1.3 mm and the shell thickness t ₀ = 0.15 mm A strain factor of 1.25 is selected. The coefficient value for various types of real fillers and deformation technology are in the range from 1 to 10.

The geometric characteristics of the element, calculated taking into account the selected sizes, will be S _ke = 0.785 mm ² , S _vol. = 0.5419 mm ² .

The geometric parameters of the finished element are determined to determine the ratio of the geometric parameters t _o / D _{0 of the} workpiece equal to 0.09868.

With the selected diameter D _{0 of the} workpiece 7 mm, the thickness t _{0 of the} shell will be 0.691 mm, and the area S _vol. the cross section of the workpiece is 13.6958 mm ² , while the length l _{e of the} finished element and the length l _{0 of the} workpiece will be equal to 7532 mm and 298 mm, respectively.

Then pre-dried powders of boron carbide and aluminum oxide are mixed in a predetermined weight ratio, for example, in a ball mill for 10 to 16 hours. Given the selected value of the coefficient of deformation compaction determine the density of 2.04 g / cm ³ and the mass of 15.07 g of a sample of the filler in the workpiece.

The initial tube billet with a diameter of D ₀ and a thickness of t ₀ , previously sealed at one end by argon-arc welding, is filled with filler using a funnel feeder on a vibrating stand with a frequency of 50 Hz for 3 minutes. Next, the filler sample is densified on the vibrator for 3 to 4 minutes until the height of the powder column is equal to l ₀ . Then seal the second end of the workpiece by installing the end element.

The resulting workpiece is deformed by drawing on linear and / or drum drawing machines to a final diameter of 1.3 mm with a single deformation per pass from 5% to 15% or intensive rolling. In order to restore the reserve of plasticity of the shell material, the deformation is carried out with intermediate vacuum anneals between deformation cycles at diameters of 3 mm and 1.8 mm and one final annealing for 2 hours at a temperature of 580 + 20 ^o C.

 If necessary, the finished element is straightened. After that, the finished element is fixed on a mandrel in a lathe and twisted into a coil "turn to turn" with a final outer diameter of 7.5 mm, thereby obtaining a spiral element with the specified parameters, which eliminates additional processing to remove excess shell material, in case of exceeding the shell thickness of the specified value or rejecting the product upon receipt of the finished element when the shell thickness is less than necessary, and also excludes trimming or rejection of the product when obtaining the length s of the finished filler element other than desired.

Claims (5)

1. A method of manufacturing an ampoule-powder system, comprising filling a powdery filler with the required characteristics in the initial tubular billet, sealing the billet, and preparing the finished element with predetermined parameters by deforming the billet, characterized in that _the shell thickness t _о , length l _о and outer are pre-selected the diameter D _{about the} initial workpiece according to the following formulas:

where S _about.E - sectional area of the shell of the finished element;
S _KE - the cross-sectional area of the powdered filler in the finished element;
S _vol.o - the cross-sectional area of the shell in the workpiece;
S _n.o. - cross-sectional area of the longitudinal insert inside the filler in the workpiece,
S _BC - the cross-sectional area of the longitudinal insert inside the filler in the finished element;
N is a coefficient that takes into account the presence of a longitudinal insert inside the filler, N = 1 in its presence, N = 0 in its absence;
l _e - the length of the finished element;

experimentally determined coefficient of deformation compaction of the filler;
γ _e is the density of the powder filler in the finished element;
γ _o - the density of the powder filler in the workpiece.  2. The method according to claim 1, characterized in that the deformation of the workpiece is carried out with at least one intermediate annealing.  3. The method according to claim 1 or 2, characterized in that the finished element is subjected to annealing.  4. The method according to any one of claims 1 to 3, characterized in that after deformation the workpiece is twisted into a spiral.  5. The method according to any one of claims 1 to 3, characterized in that the preform is twisted into a spiral simultaneously with deformation.

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