RU2441860C1 - Method for charge manufacturing from high-filled solid ballistite rocket fuel - Google Patents

Abstract

FIELD: missile and artillery technology.

SUBSTANCE: invention refers to the area of rocket and artillery materiel, namely to the methods of charge manufacturing from high-filled solid ballistite rocket fuel. The invention may be used for solid rocket fuel composition improvement and relative manufacturing technologies. The method for charge manufacturing from high-filled solid ballistite rocket fuel with fillers 15…40% (weight percent) and nitroglycerine/ cellulose nitrate - 0.6…1.0 comprises component mixing in water medium, fuel mass extraction, fuel mass rolling-pelletization, propellant pellet drying and charge pressing in a molding tool. Pelletized fuel mass shall be kept for 36…72 hours at the temperature of 15…35°C and then the charge shall be pressed in a flared-type molding tool.

EFFECT: enhancing the pressed charge quality and cutting costs of solid ballistite rocket fuel charges manufacturing.

1 dwg, 1 dwg, 1 tbl

Description

The invention relates to the field of rocket technology and can be used in the development and manufacture of a charge from ballistic solid rocket fuel (BTRT) to rocket engines of solid fuel (RTTT) and other auxiliary devices of rocket systems (gas generators of onboard power sources for rockets, batteries for boosting fuel tanks of liquid rockets , ejection devices, etc.).

Known methods for the manufacture of charges (US Pat. RU 2220934, RU 2259985, RU 2259341, RU 2259983, RU 2295050, RU 2300513, RU 2349566, RU 2360894) from formulations BTRT, providing for the content of plasticizer, usually nitroglycerin (NG), and nitrocellulose ( SC) in the ratio of NG / SC = 0.65 ... 0.75, which provides satisfactory technological properties of the BTRT formulations. However, in modern BTRT formulations, in addition to NTs and NGs, depending on the purpose of missile systems, a significant amount contains fillers of various functional purposes: stabilizers and catalysts for the burning rate, additives that reduce the level of torch formation and smoke formation of the effluent of the combustion products, explosives (HMX and etc.) and others, with this ratio of NG / SC increases up to 1.0.

In such filled formulations (with a degree of filling of more than 15 ... 40% (wt.%), The rheological characteristics of the fuel mass — the coefficients of external (F) and internal (τ) friction — are significantly deteriorated.

With the degree of filling of BTRT more than 15 ... 40% (wt.%) And increasing the weight ratio of NG / SC to 1.0, a number of difficulties arise in the processing of such systems in the pressing phase, which sometimes forces to suspend the process and even refuse to further process the fuel mixture and use it, at best, as a return-technological waste in the manufacture of regular batches of charges from the same brand of fuel. This method of fuel processing is accompanied by high economic costs.

One of the main reasons for the poor processability of highly filled BTRT compositions is the slow kinetics of plasticization of cellulose nitrates with nitroesters due to the reduction (deterioration) of their direct contact due to the high content of fillers. Therefore, an additional operation (phase) is required to ensure a high-quality process of plasticization of cellulose nitrates. The most effective and economically acceptable technological technique in this case is the “exposure-rest" for a certain time rolled-off fuel pellets.

The prototype of the patented technical solution adopted the invention according to US Pat. RU 2349566 C1 dated March 20, 2009, application 2007128659 dated July 25, 2007, IPC С06В 25/18, С06В 21/00, С06Д 5/06.

An object of the invention is to develop a method of manufacturing a charge from a highly filled BTRT, providing satisfactory manufacturability and improved ballistic (VBH) and physico-mechanical characteristics (FMX) of the processed fuel.

The technical result of the invention consists in a method of manufacturing a charge from a highly filled ballistic solid rocket fuel with a filler content of 15 ... 40% (wt.%) And a ratio of nitroglycerin / nitrocellulose 0.6 ... 1.0, including mixing fuel components in a neutral (aqueous) environment, squeezing the fuel mass, rolling-tabletting of the fuel, drying the fuel tablet and pressing the charges with the screw method through the bell and the forming press tool. Moreover, to ensure satisfactory processability, the rolled tablet is kept for 36 ... 72 hours at a temperature of 15 ... 35 ° C, that is, the technological process is carried out with phase discontinuity (rolling and molding-pressing phases) to provide a “holding-rest” time period (curing) ) rolled tablets for the implementation of relaxation processes accumulated during the extraction and rolling stresses and uniform distribution of plasticizers in the body of the tablet. After the specified time, the fuel tablet is sent to the pressing phase.

The invention is illustrated by the technological scheme (see drawing).

The essence of the invention lies in the implementation during the manufacturing process of the charge of the BTRT phase of the “hold-rest” of the rolled tablet for 36 ... 72 hours. For the specified period of time, the tablet relaxes the accumulated stresses and a natural, close to uniform redistribution of plasticizers in the volume of the fuel tablet. When pressing charges from such a tablet, the process is carried out at admissible technological parameters: pressing pressure and regulated temperature conditions.

The table shows the technological characteristics and obtained VBH and FMH fuel mixtures of ballistic type depending on the time "exposure-rest" of a fuel tablet in accordance with the patented invention.

Example No. NG / NC Mas. fraction of filler,% F, kgf / cm ² τ, kgf / cm ² Rest time, h α _t , 1 / ° C
(T = ± 50 ° C) ν, (P = 40-180 kgf / cm ² ) σ, kgf / cm ² (T = 20 ° C) 0 0.60 - 0.7 14.0 - 0.14 · 10 ^-2 5: 0.3 62 one 0.65 eighteen 2.2 25.0 - 0.16 · 10 ^-2 0.4 52 2 0.65 eighteen 2.0 18.0 12 0.16 · 10 ^-2 0.4 53 3 0.70 eighteen 1,5 16,0 24 0.16 · 10 ^-2 0.35 60 four 0.75 eighteen 1,1 13.0 36 0.14 · 10 ^-2 0.29 58

5 0.70 fifteen 0.9 12.5 48 0.14 · 10 ^-2 0.30 65 6 0.70 40 0.8 15.1 72 0.13 · 10 ^-2 0.32 68 7 0.70 thirty 0.8 15.0 96 0.13 · 10 ^-2 0.30 69 8 1,0 thirty 1,0 15.6 72 0.12 · 10 ^-2 0.27 65 Note: accepted designations NG / SC - the weight ratio of the components of NG and SC; F is the coefficient of external friction; τ is the coefficient of internal friction; α _T is the temperature gradient of the fuel combustion rate; ν is the exponent in the power law of the rate of fuel combustion at 20 ° C; σ is the tensile strength of the fuel.

Sample "0" is considered as a standard, which has satisfactory technological characteristics and is manufactured by the method - the prototype.

(α_T) и показателя «ν» в степенном законе скорости горения отпрессованного топлива.An analysis of the results given in the table allows us to conclude that the rupture of the rolling and pressing phases is effective in the processing of highly filled BTRT with the introduction of the operation (phase) of “holding-rest” of the fuel tablet at T = 15 ... 35 ° C for 36 ... 72 h, so how the specified processing method provides not only an improvement in the rheological characteristics of the fuel mixture, but also contributes to an increase in the physicomechanical and combustion characteristics of the fuel — a decrease in the temperature gradient of the combustion rate

(α _T ) and exponent “ν” in the power law of the burning rate of pressed fuel.

At the same time, the temperature range of the “exposure-rest" tablet is selected taking into account:

- at the lower limit - at least 15 ° C, given the crystallization temperature of nitroglycerin (13 ° C);

- according to the upper limit - not more than 35 ° C, from the point of view of preventing the undesirable initial stages of thermal decomposition of the components included in the BTRT formulation.

Experimental studies show that the introduction of the “soak-rest” phase of the rolled tablet within 12-24 hours (examples 2, 3 of the table) does not provide a noticeable increase in the technological characteristics of the fuel, and the increase in the “soak-rest” time range from 36 to 72 hours ( arr. 4, 5, 6) improves not only the technological properties of the fuel, but also its output characteristics (VBH, FMH), especially in comparison with arr. No. 1, which was processed without the use of the "exposure-rest" phase. An increase in the “holding-rest” time of more than 72 hours is impractical (Example 7), since all the processes involved in ensuring the uniformity of the fuel tablet comply with the Arrhenian law (proceed according to exponential dependencies) and are completed by 90 ... 95% within 36 ... 72 hours ( examples 4-6, 8).

The introduction of the “hold-rest” phase into the manufacturing process of the charge provides the required workability of pressing and relieving residual stresses in the fuel pellet, which significantly reduces the level and dispersion of the additive of pressed charges, helps to reduce the dispersion of the CVC of charges and increase the efficiency of missile systems in general (due to stabilization geometric dimensions of charges).

The positive effect of the invention is to increase the efficiency of the charges of BTRT for solid propellant rocket engines and lowering the economic costs of their manufacture.

Claims (1)

A method of manufacturing a charge from a highly filled ballistic solid rocket fuel with a filler content of 15-40% (wt.%) And a ratio of nitroglycerin / nitrocellulose 0.6-1.0, including mixing the components in an aqueous medium, squeezing the fuel mass, rolling-tabletting of the fuel mass drying the fuel pellet and compressing the charge through a forming tool, characterized in that the pelletized fuel mass is held for 36-72 hours at a temperature of 15-35 ° C, after which the charge is pressed through cutting press tool.

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