RU2215721C2 - Method of inhibiting inserted solid-propellant charge - Google Patents

Abstract

FIELD: rocketry; methods of inhibiting solid-propellant charges. SUBSTANCE: solid-propellant charge is placed in mold positioned vertically and inhibiting compound is poured in gap between solid- propellant charge and mold at excess compensating for shrinkage during polymerization; then mold is immersed in thermal chamber for polymerization of inhibiting compound; polymerization of inhibiting compound is performed in succession by layers in charge height beginning with lower part at gradual introduction of mold into thermal chamber; then cooling is carried out to normal temperature and charge is withdrawn from mold. EFFECT: improved quality of acrylate inhibiting coat; enhanced efficiency. 3 dwg

Description

 The invention relates to the manufacture of rocket technology, in particular, relates to a method for booking charges of solid rocket fuel (TRT) by pouring armored vehicles having polymerization shrinkage.

 One of the well-known methods of booking TRT plug-in charges is the filling method, which consists in installing the armored charge in the mold and filling the gap between the charge and the form with liquid armored personnel, polymerizing the armored personnel and removing the reserved charge from the mold.

The advantage of the method is the possibility of simultaneously booking the end and side surfaces of the charge. The polymerization of the armor during the booking of charges by pouring is carried out either at room temperature of 15-30 ^o C, or at elevated temperatures of 60-90 ^{o C.} In this case, the casting mold with the product is placed in the polymerization heat chamber completely. The quality of the armor coating is obtained, as a rule, satisfactory when working on many well-known compositions (armor based on epoxy resins, polyurethanes, polysulfides and other compounds) with low polymerization shrinkage (less than 4.0%).

However, the generally accepted method for the polymerization of an armored composition during reservation by casting does not provide high quality when using armored compounds having a large polymerization shrinkage (reaching up to 10%), in particular acrylate armored compounds, for example, armored compounds containing methyl methacrylate and butyl methacrylate, which found their high protective ability and purity of products decomposition is widely used for booking small-sized charges for various PAD and GG. Large polymerization shrinkage leads to the formation of defects in the armor coating in the form of detachments from the fuel, shrinkage recesses, bumps and even cracks. In the work carried out by the authors, it was found that the type of shrinkage defects depends on the polymerization mode. At an increased polymerization temperature of 60-90 ^o C, shrinkage stresses in some areas lead to the separation of the armor coating from the TPT checker and the formation of local glue at the gunpowder-armor coating interface as a result of the higher rate of polymerization of the armor at the border with the heated form compared to the polymerization rate at the border with gunpowder . At a normal curing temperature of 15-30 ^o C on the outer surface of the armor coating various kinds of convolutions, dents, shells and other defects are formed due to the uneven shrinkage of the armor. The most pronounced shrinkage defects on the armor plating are manifested on cone charges having unequal thickness of the side armor plating at the upper and lower ends, and on charges with a large thickness of the side plating.

A known method used in world practice to obtain block polymethyl methacrylate by polymerization of methyl methacrylate in the presence of initiators in a closed form, as well as the preparation of rods and tubes by block polymerization of methyl methacrylate according to US patent 2057674. Shrinkage of polymerizable methyl methacrylate is compensated by the continuous supply of prepolymer under pressure in the upper part tubes. The pressure is created by nitrogen, compressed to 12-20 kgf / cm ² . The disadvantage of this method is the need to create special conditions, in particular the presence of excess pressure of carbon dioxide or nitrogen (up to 12-20 kgf / cm ² ) with all the ensuing consequences. First of all, it is the need to seal casting molds and thermostats, supply production with carbon dioxide or nitrogen, and constantly monitor the polymerization unit.

 The closest in technical essence is the method of booking the TRT deposit charge by filling using various forms (Brief Encyclopedic Dictionary "Energy Condensed Systems", edited by B. P. Zhukov, M., "Janus-K", 2000, p. 263) - prototype. This reservation method requires heating of special forms, limited in size, and a simultaneous fleet (polymerization) of armored personnel is produced, but this method is suitable for booking charges with compounds with low polymerization shrinkage. And for charges armored with acrylate armor with polymerization shrinkage of up to 10% or more, this method is not acceptable, since it is impossible to obtain high-quality armor plating in the form of limited dimensions due to the formation of shrinkage defects.

 An object of the present invention is to develop a method for booking TRT charges by pouring under normal conditions, which allows to ensure high quality acrylate armor plating when using acrylate armor compounds with high polymerization shrinkage.

The task of high-quality booking of TRT charges by the filling method is solved as follows: the charge of solid rocket fuel is placed in a vertically installed form and poured from above into the gap between the armored charge and the shape of the armor composition with excess compensating for shrinkage during its polymerization, immersed in a heat chamber for polymerization of the armored composition at temperature 60-90 ^o C, the polymerization bronesostava are sequentially layers of charge adjustment, starting from the bottom, by a gradual entry forms in ter okameru maintaining the air temperature above the end surface shape that is outside the heat chamber, 25-35 ^o C, cooling is then carried out to normal temperature and breakup armored charge from the mold.

 Thus, the polymerization is carried out in layers, starting from the bottom, for which it is proposed that the form with a charge filled with an acrylate armor composition be lowered into the polymerization heat chamber stepwise, in two or more stages.

For example, at first the form is immersed only at 1/3 of its height, can withstand some time, immersed at another 1/3 of the height, etc. The number of steps and the amount of immersion in each method is selected so that the rate of polymerization of the armor in the lower part of the mold during the entire polymerization process is higher than in other parts. In this case, the shrink volume is compensated by the arrival of liquid armor from the overlying form layers and shrink defects in the armor coating are not formed. In the upper part of the reservation form, it is proposed to provide a profitable bowl, from where the armored personnel, as they shrink, enter the gap between the armored charge and the form. In this case, the air temperature above the surface of the armored personnel carrier in the profitable bowl should be 25-30 ^o С. To ensure high quality armor plating, the required immersion depth and the number of steps should be selected for each new type of charge depending on its configuration, size, thickness of the armor plating.

The test of the proposed stepwise method of polymerization of the armored personnel was carried out when booking the following channel-free charges of dibasic fuel:
1. The conical charge. Small diameter 81 mm, large diameter 87 mm, length 175 mm, armor plating thickness at the top of 8 mm, at the bottom 4 mm.

 2. The cylindrical charge. Diameter 131 mm, length 461 mm, armor plating thickness 4 mm.

 3. The cylindrical charge. Diameter 176 mm, length 1100 mm, armor plating thickness 7 mm.

 The body composition (based on butyl methacrylate) had a shrinkage of 9%. The required number of stages of polymerization and the depth of immersion for each stage was determined experimentally by determining the rate of polymerization of the armor at various levels by charge height (in the lower, middle and upper parts of the molds) and by selecting a mode that provides a higher polymerization rate in the lower part. The polymerization rate of the armored personnel was determined by measuring the temperature of the armored personnel (during polymerization, the temperature of the armored personnel increases due to the exothermic effect). To obtain good quality armor plating on the first two charges, a two-stage polymerization mode was sufficient, and for a third charge a three-stage one.

 In FIG. 1 shows the appearance of the charge obtained by the known booking method (1b) and the proposed method (1a).

The charge form, filled with an acrylate armored composition, was immersed in a polymerization heat chamber with a temperature of 70 ^° C, first at 2/3 of the height, aged 2.5-3.0 hours, then immersed completely and maintained for another 3.0 hours until the armor composition was completely polymerized. The air temperature above the surface of the armored personnel carrier in the profitable part was within 25-35 ^o C. The kinetics of polymerization of the armored personnel carrier is shown in figure 2.

 The layered nature of the polymerization of the proposed method is confirmed by special experience. Figure 3 shows the charge 2 installed on the stand 1 in the socket 5 of the polymerization cabinet 3, heated by the steam-water mixture 4. The charge 2 in the middle of the polymerization process was removed from form 6 and examined for the quality of the armor coating. In the lower part of charge 2, the armor coating 7 was completely polymerized, in the middle part 8 it was gel-like, and in the upper part 9 it was liquid.

 From the foregoing it is clear that the positive effect of the proposed booking method can be obtained on any other armored vehicles with high polymerization shrinkage.

 It should be noted that when applying the proposed booking method, the internal stress in the gaps decreases. It is known that high stresses arise in the gap when booking by the conventionally known method due to polymerization shrinkage, which can lead to a decrease in the physical stability of the charge. When booking by the proposed method there is no such danger, since the polymerization proceeds gradually from the bottom up without shrinkage stresses in the charge.

 The proposed method of booking TRT plug-in charges has been implemented at the Federal State Unitary Enterprise Perm Plant named after S.M. Kirov.

The manufacture of charges by the proposed method allows you to:
- improve the quality of charges;
- provide the necessary level of ballistic characteristics;
- reduce the complexity of manufacturing charges.

Claims (1)

A method of booking a solid solid rocket propellant charge charge by casting, characterized in that the solid rocket propellant charge is placed in a vertically mounted mold and poured from above into the gap between the armor charge and the armor form in excess to compensate for shrinkage during its polymerization, immersing the mold in a heat chamber for polymerizing the armored part a temperature of 60-90 ^o C, while the polymerization of the armor is carried out sequentially in layers along the height of the charge, starting from the bottom, by gradually entering the form into the heat chamber maintaining the temperature of the air above the end surface of the mold, located outside the heat chamber, 25-35 ^o C, then carry out cooling to normal temperature and the molding of the armored charge from the mold.

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