RU2365778C1 - Method for manufacturing spherical overlapping of rubberised fabric cover - Google Patents

Abstract

FIELD: mechanical engineering.

SUBSTANCE: invention is attributed to rocket engineering. Method for manufacturing spherical overlapping of rubberised fabric cover for protection of sectors set forming annular groove in channel for composite propellant charge is suggested. Spherical overlapping blank is fabricated of uncured calandered rubber with fabric underlayer through compacting it between flat press plates under pressure of 40 to 120 kgf/cm² at temperature of 15 to 30°C for 5 to 25 min, then produced blank part is formed and cured on holder.

EFFECT: invention is aimed to increase strength of rubber-fabric bonding in the process of spherical overlapping manufacturing.

2 cl, 2 tbl

Description

The proposed method relates to techniques for the manufacture of charges of mixed solid rocket fuel with an annular groove in the channel, molded using a cone from a set of sectors placed in a rubber-fabric protective cover.

A known method of manufacturing a rubber fabric cover according to the patent of the Russian Federation 2300656, adopted by the authors as a prototype.

In this technical solution, the cover elements - sheets and curly elements (pads) - are made of calendared rubber, duplicated with a reinforcing fabric. In this case, the manufacture of elements is carried out by joint vulcanization of rubber sheets with fabric under pressure.

Unlike flat sheets, the vulcanization of which is carried out under high pressure in the press, the shaped plate, which is a part of the torus with conical sections adjacent to it, is vulcanized in an air thermostat under very slight pressure, which is carried out by winding (unscrewing) the blank to the blank "- an annular metal mandrel imitating the curly part of the cone - with cotton tape.

However, during vulcanization in the thermostat, the pressure created by the winding tape is clearly not enough, which leads to low bond strength of rubber with fabric, peeling, bubbling and fingerprints on the strip. In addition, when wrapping the “raw” rubber can deform strongly, forming folds.

In principle, the blank of the plate could be made on the press between flat plates, however, it is practically impossible to obtain a high-quality figured plate in the future (to give it the desired shape).

The technical result of the invention is to eliminate these drawbacks and thereby improve the quality of the lining and, therefore, the quality of the charge.

This goal is achieved by the fact that in the method of manufacturing a spherical lining of a rubber-fabric cover for protecting a set of sectors forming an annular groove in the charge channel from a mixed rocket solid fuel, including obtaining a spherical lining by molding on a mandrel and subsequent vulcanization of calendared rubber with a fabric substrate, before molding preliminary pressing of the blank of unvulcanized rubber with fabric between flat plates at a temperature of 15 ... 30 ° C under a pressure of 40 ... 120 kgf / cm ² for 5 ... 25 min.

Moreover, if necessary, pressing the workpiece can be carried out in successive sections with an overlap of the pressing zone from 10 to 30 mm

Thus, the preliminary connection of crude rubber with fabric according to the above modes can dramatically improve the mechanical properties of the workpiece without losing its elasticity and formability.

The method is as follows. A strip of a triacetate film is laid on the bottom plate of the press, then a raw fat-free rubber blank, a strip of reinforcing fabric, having a width 10 ... 20 mm greater than the width of the rubber blank and overlapped from strips cut at an angle of 45 ° ± 15 ° to the base, a strip of triacetate film . After that, the upper press plate is lowered, the required pressure is created and maintained. After exposure, the upper press plate rises, the workpiece moves along the plates so that the pressed section remains in the pressing zone for a length that ensures no imprint from the junction of the pressing sections. It has been experimentally established that an overlap of 10 ... 30 mm is enough to avoid the manifestation of edge effects.

The process is repeated until the completion of pressing the entire workpiece.

The resulting preform is a sufficiently firmly joined together sheets of crude rubber and fabric due to the introduction of rubber into the fabric structure, while the elasticity and formability of the preform in the transverse direction are quite sufficient to obtain a high-quality lining after vulcanization.

Then the blank blanks are removed from the press, imposed on the mandrel (figure 1), bandaged, placed in an air thermostat and vulcanized. After vulcanization, the winding tape is removed, the molded pad is sent for further assembly.

Examples of the method are shown in tables 1 and 2.

The conditions for the process of pressing the workpiece blank

Table 1 Sample No. one 2 3 four 5 6 7 8 9 10 eleven Temperature ° C fifteen fifteen fifteen fifteen fifteen fifteen fifteen fifteen thirty thirty thirty Pressure, kgf / cm ² twenty thirty 40 90 120 150 40 40 40 90 120 Pressing time, min 10 10 10 10 10 10 5 four four four 25

Results

table 2 No. p / p Characteristics of the lining after vulcanization Conclusion one The bonding of rubber with fabric is weak and uneven, local delamination of the force during delamination after vulcanization from (0.0 ÷ 0.5) kgf / cm at the required 0.8 kgf / cm min. Penetration of rubber through the fabric is absent. The rubber surface has irregularities. The overlay does not meet the requirements of normative and technical documentation (NTD). Marriage

No. p / p Characteristics of the lining after vulcanization Conclusion 2 The bonding of rubber with fabric is weak, the force during delamination after vulcanization max 0.6 kgf / cm, insufficient. Penetration of rubber through the fabric of about 20% of the surface. The rubber surface has irregularities. The overlay does not meet the requirements (NTD). Marriage 3 The bonding of rubber with fabric is satisfactory; the force during delamination after vulcanization is 0.9–1.1 kgf / cm. The surface of the rubber is smooth. The overlay meets the requirements of NTD. The overlay can be directed for its intended purpose. four The bonding of rubber to fabric is good, the force during delamination after vulcanization is 1.1 ÷ 1.5 kgf / cm. Penetration of rubber through the fabric of about 70% of the surface. The surface of the rubber is smooth. The overlay meets the requirements of NTD. The pad is intended for its intended purpose. There are no comments on the surface of the channel. 5 The bonding of rubber with fabric is good, the force during delamination after vulcanization is (1.2 ÷ 1.7) kgf / cm. Penetration of rubber through the fabric of about 80% of the surface. The surface of the rubber in the stains, which are removed when sanding, provided by the process. The overlay meets the requirements of NTD. The pad is intended for its intended purpose. There are no comments on the surface of the channel. 6 The bonding of rubber with fabric is good, but the reinforcing fabric has randomly located gaps filled with rubber, the force during delamination after vulcanization of 1.0 ÷ 1.7 kgf / cm The rubber surface has furrows up to 0.2 mm deep. The overlay does not meet the requirements (NTD). Marriage 7 The bonding of rubber with fabric is satisfactory, the force during delamination after vulcanization of 0.8 ÷ 1.1 kgf / cm Penetration of rubber through the fabric about 30% of the surface. The surface of the rubber is smooth. The overlay meets the requirements of NTD. The overlay can be directed for its intended purpose. 8 The bonding of rubber with fabric is weak, the force during delamination after vulcanization is 0.6 ÷ 1.0 kgf / cm. Penetration of rubber through the fabric of about 20% of the surface. The surface of the rubber is smooth. The overlay does not meet the requirements (NTD). Marriage 9 The bonding of rubber with fabric is weak, the force during delamination after vulcanization is 0.7 ÷ 1.2 The overlay does not meet the requirements (NTD).

No. p / p Characteristics of the lining after vulcanization Conclusion kgf / cm Penetration of rubber through the fabric of about 40% of the surface. The rubber surface is smooth, but there are bubbles on the rubber with a height of 0.1 ÷ 0.2 mm in an area of about 5% Marriage 10 The bonding of rubber with fabric is satisfactory; the force during delamination after vulcanization is 0.9–1.3 kgf / cm. Penetration of rubber through the fabric is about 60%, but there are delaminations in some areas. Smooth rubber surface The overlay does not meet the requirements (NTD), the overlay repair is required eleven The bonding of rubber to the fabric is good, but the reinforcing fabric has tears in the middle of the strip. The force during delamination after vulcanization of 1.1 ÷ 1.6 kgf / cm. Penetration of rubber through the fabric is about 100%. The surface of the rubber in the stains that are removed when sanding. The overlay does not meet the requirements (NTD). Marriage

Claims (2)

1. A method of manufacturing a spherical lining of a rubber-fabric cover for protecting a set of sectors forming an annular groove in a charge channel of mixed solid rocket fuel, characterized in that the blank of a spherical lining is made of unvulcanized calendared rubber with a fabric substrate by pressing between flat press plates under a pressure of 40 ... 120 kgf / cm ² at a temperature of 15 ... 30 ° C for 5 ... 25 min, then the resulting preform is molded and vulcanized on a mandrel. 2. The method according to claim 1, characterized in that the pressing is carried out in successive sections along the length of the press plates with an overlap of the pressing zone from 10 to 30 mm.