RU2583863C2 - Folding parabolic reflector and method of making same - Google Patents

Abstract

FIELD: machine building.

SUBSTANCE: folding parabolic reflector has flexible ribs, covered with net cloth. Flexible ribs are made from material with double thermomechanical shape memory for preset extreme values of temperature during operation of reflector. To endow reflector with double shape memory, reflector is mounted in a template made from material with minimum thermal expansion coefficient and subjected to heat cycling in amount of cycles equal to no less than 10 at extreme temperature conditions of operation. As a result, during heating and cooling of reflector, required shape of reflecting surface is maintained.

EFFECT: technical result consists in improvement of stability of shape of reflecting surface of reflector at variation of ambient temperature.

2 cl, 2 dwg

Description

The invention relates to antenna technology and can be used in large antennas designed to operate in a wide temperature range.

Known "Folding reflector" containing a rigid central panel, side panels pivotally attached to it, rigid radial ribs pivotally mounted on a rigid central panel (see AS No. 890920), improving the accuracy of the surface in this reflector is achieved by introducing rigid radial ribs, which in turn, increase the mass of the structure.

The well-known "Folding skeleton of a parabolic antenna", consisting of the main and auxiliary rigid rods interconnected pivotally and form triangular cells, as well as opening mechanisms connected to triangular cells using hinged nodes (see AS No. 814212).

As a prototype of the device, the design of a large-sized parabolic reflector (diameter 55 m) containing flexible graphite-epoxy stiffeners was chosen. In the folded position, the ribs are wound on a central cylindrical hub. The deployment of the reflector is due to elastic forces. A grid is stretched between the ribs (see the journal "Rocket and Space Technology" No. 33 of 08/17/84 p. 13-15). The antenna was developed by Lockheed Missiles and Space and is designed to work in space.

As a prototype of the (basic) method, the method of manufacturing a folding parabolic reflector from titanium nickelide, described in the article “Memory of Metals” by V. Khachin, published in the journal “Science and Life” No. 3-1980, was selected. It consists in assembling the reflector frame in the working position, heating it to the storage temperature of the form, followed by cooling to normal temperature and folding to the required compact geometric dimensions.

A disadvantage inherent in all large-sized structures operating in a wide temperature range, including parabolic antennas, is the distortion of their shape due to thermal deformation. In addition, a mechanism is needed to open the reflector, the mass and dimensions of which increase with the size of the reflector, worsening the characteristics of the reflector.

The aim of the invention is to reduce the influence of temperature deformation on the geometric shape of the reflector.

This goal is achieved by the fact that in the known folding parabolic reflector containing flexible stiffeners, covered with a net-sheet, stiffeners are made of material with double thermomechanical memory.

A method of manufacturing a collapsible parabolic reflector with stiffeners made of material with a thermomechanical memory consists in manufacturing ribs with a parabolic profile, setting them a “warm shape memory” that appears at the maximum temperature of the operating range, after which the ribs are fixed in a conductor from a material with a minimum coefficient linear expansion and is subjected to thermal cycling in the temperature range of operation of the reflector to obtain a cold shape memory.

The criterion of "significant differences" meets:

a) in the device, the manufacture of flexible stiffeners from a material with double thermomechanical shape memory;

b) in the method, the thermal cycling of stiffeners fixed in the conductor in the operating temperature range until they develop a “cold shape memory”.

In the materials available to the authors, there are no signs of the claimed technical solution.

Figure 1 shows a General view of a folding parabolic reflector. Figure 2 shows the diagram of the "work" of one of the stiffeners when exposed to extreme temperatures of the operating range.

A folding parabolic reflector contains flexible stiffening ribs 1, dividing it into separate sectors 2, a net-cloth 3 is stretched between the ribs, the ribs are connected to the base 4.

The design of the reflector works as follows.

In the folded position, the ribs 1 are wound on the base 4 and fixed. The deployment of the reflector occurs after removing the elements of the fixing of the ribs due to the combination of forces:

a) the elastic forces of the ribs of sectors 2,

b) the forces of the "memory of the warm form" of the material of the ribs 1 that occur when exposed to temperatures in the operating range.

Setoplot 3 at the same time straightens and stretches. The program for maintaining the given reflector configuration is embedded in the memory of the material shape of each of the stiffeners 1.

When the ribs are exposed to a temperature close to the maximum, it tends to position 5 under the influence of thermal expansion forces, however, they are counteracted by the forces of a “warm-shape memory”.

At the minimum temperature of the operating range, the forces of thermal deformation tend to bring rib 1 to position 6, however, the forces of the "cold shape memory" prevent this.

In this case, the geometric shape of the reflector is kept close to the desired theoretical.

As an example of the method of manufacturing the reflector, a process of manufacturing and training stiffeners is provided in order to ensure the operability of the reflector in the range from -150 to + 150 ° C.

For the manufacture of stiffeners, an alloy in the form of a tape is used according to TU1-809-193-77, which is given a parabolic bend that corresponds to the theoretical in the open position of the reflector and set the material to "warm shape memory" by heating it to a temperature of 500 ° C, kept at this temperature not less than 1 hour, then cooled to normal temperature (10-30) ° C. After the reflector is assembled, its ribs in the open operating state are fixed in conductors, eliminating or minimizing the distortion of the shape of the ribs under the influence of temperatures. Conductors can be made, for example, of a superinvar having a very small coefficient of linear expansion. The reflector with ribs fixed in the conductors is subjected to thermal cycling in the range of ± 150 ° C in order to obtain a second “cold shape memory” in the amount of 3 ÷ 10 cycles.

After thermal cycling, the ribs released from conductors during cooling return to the position specified by the conductors, and when heated, as before, they retain their original shape, set at a temperature of 500 ° C. In other words, the NiTi material acquired a double shape memory (see Zamoysky VA, Kolupaeva TL, Unusual Properties of Conventional Materials “Science”, M., 1984, pp. 135-137).

Thus, the implementation of the stiffening ribs of the reflector from a material with double shape memory and the use of thermal cycling between extreme temperatures of the operating range allows you to:

a) increase the stability of the geometric shape of the reflector in the temperature range of operation.

b) to simplify the design and increase the reliability of the reflector by canceling a special complex drive for opening the reflector.

Claims (2)

1. Folding parabolic reflector containing flexible stiffeners fitted with a net-sheet, characterized in that, in order to improve the shape of the reflector in a given operating range, the ribs are made of a material with double thermomechanical shape memory. 2. A method of manufacturing a collapsible parabolic reflector according to claim 1, which consists in the manufacture of ribs from a material with thermomechanical memory, giving them the required parabolic profile by heating to the “warm form” memory temperature, which manifests itself at the maximum temperature of the operating range, characterized in that the ribs are fixed in a conductor made of a material with a minimum coefficient of linear expansion, and is subjected to thermal cycling between extreme temperatures of the operating range eflektora at least 10 cycles to obtain their memory "cold form".

Images