RU2067340C1 - Method of and device for producing reflecting surface of mirror antenna reflector - Google Patents

Abstract

FIELD: manufacture of mirror antenna reflectors. SUBSTANCE: in manufacturing reflector 1, blank surface is divided along generating line into sections. Cutting tool on each section is set in motion along circumference arc in plane crossing longitudinal axis of blank and in radial movement relative to center of this circumference. Parameters of the latter are determined proceeding from equality of arc length of this circumference and theoretical curve determining outline of reflector on this section. Expression for determining radial displacement distance compensating for arc deviation from theoretical curve of reflector is given in description of invention. Design of turning milling head affording desired displacement of cutting tool and relationship for determining parameters of kinematic circuit are also given there. EFFECT: facilitated procedure. 2 cl, 4 dwg

Description

 The invention relates to antenna technology and can be used for the manufacture of reflector reflector antennas.

A known method of obtaining bodies of revolution with variable curvature of the surface, which consists in approximating the generatrix of the curve by straight sections [1]
This method finds application in the manufacture of solid reflective surfaces of various types for reflector reflector antennas on machines with numerical control. However, this method does not allow to obtain a high-quality surface, in particular rotation paraboloids, due to approximation errors, tool positioning errors for a large number of reference points, as well as discrete changes in the angle of inclination of straight sections. The latter also leads to a deterioration in surface cleanliness in the zones of reference points.

 Closest to the proposed is a method of obtaining a reflective surface of the reflector and a device for its implementation [2] taken as a prototype. In accordance with the prototype method, the working edge of a rotating cutting tool sets the movement in the axial plane relative to the rotating workpiece along an arc of a circle whose center is on the focal axis of the reflector. This method is implemented quite simply.

 The prototype device for processing the reflective surface of the reflectors contains a rotary table for fixing the billet reflector reflector antenna and mounted above the rotary table rotary milling head with a spindle and a cutting tool.

 The surface of the reflector, processed in this way and on this device, has a higher accuracy and purity. However, this method and device for its implementation allow to obtain a reflective surface of only a spherical type. At the same time, increasing the technical characteristics of mirror antennas makes it necessary to perform the reflective surface of the reflector, not only spherical, but also of other types. And this requires increasing the accuracy of manufacturing the reflective surface of the reflector.

 The purpose of the invention is to improve the accuracy of the surface of the reflector.

где Δ_1i, Δ_2i максимальные значения величины недореза и подрезания теоретического профиля рефлектора на i-ом участке при перемещении режущего инструмента по дуге окружности, определяемой из условия равенства длин дуг этой окружности и теоретической кривой;
Сi коэффициент, значение которого находится в пределах от 0 до 0,4;
Φ угол, который изменяется в пределах от 0 до 2π.This goal is achieved by the fact that in the method of obtaining the reflective surface of the reflector of the mirror antenna, in which the billet of the reflector of the mirror antenna is rotated relative to its longitudinal axis, the cutting tool is rotated relative to its own axis and moved along a circular arc in the plane passing through the longitudinal axis of the workpiece of the reflector of the mirror antenna , according to the invention, they break the surface of the workpiece along the generatrix into i sections, move the cutting tool along an arc of a circle in a plane, pass boxes through the longitudinal axis of the billet of the reflector of the mirror antenna, sequentially on each i-th section, and the circumference parameters are determined from the condition that the lengths of the arcs of this circle are equal to a theoretical curve, for example, a parabola that determines the profile of the reflector of the mirror antenna on this section, the cutting tool on each i- Ohm section give relative to the center of the circle a radial displacement, determined from the expression:

where Δ _1i , Δ _{2i are the} maximum values of undercutting and cutting the theoretical profile of the reflector in the i-th section when moving the cutting tool along an arc of a circle, determined from the condition that the lengths of the arcs of this circle are equal and the theoretical curve;
Сi coefficient, the value of which is in the range from 0 to 0.4;
Φ is an angle that varies from 0 to 2π.

где μ величина радиального перемещения инструмента;
l длина кривошипа кулисного механизма;
P шаг передачи винтовой пары;
D диаметр начальной окружности зубчатого колеса реечного механизма;
i_PB передаточное отношение второго редуктора;
C эксцентриситет некруглых зубчатых колес;
v угол поворота ведущего некруглого зубчатого колеса.This goal is also achieved by the fact that in the device for obtaining a reflective surface of a reflector of a mirror antenna, comprising a rotary table for fixing a blank of a reflector of a mirror antenna, a rotary milling head with a spindle and a cutting tool mounted above the rotary table, according to the invention, the cutting tool is mounted for radial movement why the rotary milling head is equipped with a guide, in which a slider with a guide in which a spindle with a cutting tool is mounted with the possibility of radial movement, a gear sector coaxial to the suspension axis of the rotary milling head is rigidly connected to this axis and kinematically connected to the slider by means of gearboxes and a screw pair installed in the rotary milling head, and also located between gearboxes pairs of non-circular, for example, elliptical, gears, rocker and rack mechanisms, in which the link and the rack are rigidly interconnected, while the gear ratio is primary about the gearbox between the non-circular wheels and the gear sector is equal
i _ns = 2π / β _i ,
where β _{i is the} central angle corresponding to the arc of the i-th section, and the parameters of the kinematic chain between this gear and the slider are determined by the relation

where μ is the value of the radial movement of the tool;
l the length of the crank rocker mechanism;
P pitch transmission screw pair;
D is the diameter of the initial circumference of the rack gear;
i _PB gear ratio of the second gear;
C eccentricity of non-circular gears;
v the angle of rotation of the drive non-circular gears.

 It is the claimed design embodiment of the rotary milling head with the specified kinematic connection between the axis of its suspension and the spindle with a cutting tool provides, according to the method, the complex movement of the cutting tool and the achievement of the purpose of the invention. This allows us to conclude that the claimed invention is interconnected by a single inventive concept.

 Comparison of the claimed technical solutions with the prototype and analogues allows us to establish that they are unknown from the prior art and, therefore, meet the criterion of "novelty."

 An analysis of the claimed technical solutions shows that they have an inventive step, since for a specialist they do not explicitly follow from the prior art.

 The invention is industrially applicable, as it can be used for the industrial production of antenna technology in the manufacture of reflector reflector antennas.

The invention is illustrated by drawings, where figure 1 presents a diagram of the processing of the reflective surface of the reflector; figure 2 diagram of the calculation of the processing error when moving the cutting tool along an arc of a circle; in FIG. 3 graphs of the radial movement of the tool and the processing error when moving the cutting tool along an arc of a circle; figure 4
kinematic diagram of a device for processing a reflective surface of a reflector.

,
где X_A, X_Б, Y_A, Y_Б координаты точек А и Б теоретической кривой;
L_i длина дуги теоретического профиля на i-м участке

y' первая производная функция y;
l_i длина хорды между точками А и Б

γ_i угол наклона хорды АБ к оси Х
γ_i= arctg[(y_Б-y_A)/(x_Б-x_A)].
Погрешность обработки при указанных начальных условиях (перемещение инструмента по дуге окружности) определяется по величине отклонения Δ_i (фиг. 2) дуги окружности b_i на i-ом участке от теоретического б профиля по зависимости
Δ_i= S_i-R_i
где S_i расстояние от точки С теоретического профиля i-го участка с координатами (X_ci, Y_ci) до точки О_i

График начальной погрешности обработки Δ_i на i-ом участке представлен на фиг. 3. Экстремальные точки этого графика определяют максимальные значения величины недореза Δ_1i и подрезания Δ_2i теоретического профиля дугой окружности.To process the reflecting surface a (Fig. 1) of the reflector antenna 1, the theoretical surface b (Fig. 2), defined in the axial plane by the function yf (x), is broken down along the generatrix into several sections. For each i-th section, limited by points A and B, the circle parameters of the coordinate of the center t are determined. O _i (X _oi , Y _oi ) and the radius value R _i along the arc of which the main portable movement of the working edge of the cutting tool 2 is performed, according to the dependencies:
x _oi = (x _A + x _B ) / 2-R _i cos (β _i / 2) sin γ _i ;
y _oi = (y _A + y _B ) / 2-R _i cos (β _i / 2) cos γ _i ;
R _i = L _i / β _i ;

,
where X _A , X _B , Y _A , Y _{B are the} coordinates of points A and B of the theoretical curve;
L _{i the} length of the arc of the theoretical profile in the i-th section

y 'is the first derivative of y;
l _i chord length between points A and B

γ _{i the} angle of the AB chord to the X axis
γ _i = arctan [(y _B -y _A ) / (x _B -x _A )].
The processing error under the specified initial conditions (tool movement along the circular arc) is determined by the deviation Δ _i (Fig. 2) of the circular arc b _i in the i-th section from the theoretical b profile according to
Δ _i = S _i -R _i
where S _{i is the} distance from point C of the theoretical profile of the i-th section with coordinates (X _ci , Y _ci ) to point O _i

The graph of the initial processing error Δ _i in the i-th section is shown in FIG. 3. The extreme points of this graph determine the maximum values of the undercut Δ _1i and truncation Δ _{2i of the} theoretical profile by an arc of a circle.

Then, according to the dependence for ΔR _i in accordance with the nature of the graph Δ _i and the maximum values of undercut Δ _1i and truncation Δ _2i , the value of the coefficient C _i is determined so that the values of the function ΔR _i differ from the values of the function Δ _{i by} no more than a predetermined error (deviation of the actual profile of a reflector from theoretical b). It is taken into account that the upper signs in front of the coefficient C _i shift the extreme points of the function ΔR _i closer to points A and B, and the lower signs closer to the middle of the section. The value of the coefficient C _i for the i-th section under consideration is constant.

The function ΔR _i found by calculations is presented in Fig. 3 and determines the additional radial displacement of the working edge of the tool in the i-th portion of the reflector processing. This movement compensates for the initial error Δ _i . The value of the coefficient C _i in the range from 0 to 0.4 is taken because they allow you to get the maximum approximation of the function ΔR _i to the function (- (-Δ _i )).

The total error of the processing of the reflector by the proposed method is determined by the deviation Δ _{Σi of the} actual profile a _i from theoretical b according to the dependence:
Δ _Σi = S _i - (R _i + ΔR _i ) = Δ _i -ΔR _i .
After determining the processing parameters, the billet of the reflector 1 can be given rotation around the focal axis (the y axis passes along it), and the cutting edge of the rotating tool 2 (for example, milling cutters) can be moved in the axial plane around the center О _{i of} radius (R _i + ΔR _i ) in angle solution β _i . After processing one section, a setting can be made to process the next section and processing it.

 The device (Fig. 4) for obtaining the reflective surface of the reflector 1 of the mirror antenna by means of the cutting tool 2 comprises a rotary table 3, on which the billet of the reflector is placed, and a rotary milling head 4 with spindle 5 and tool 2 mounted above the barrel. The milling head 4 is mounted on a stand beds (not shown in the figure) using the suspension axis 6 and the sliders 7 and 8. The sliders 7 and 8 have the ability to move in the vertical and horizontal directions, changing the position of the suspension point of the milling head, and Suspension allows the milling head 6 to rotate relative thereto.

 The rotary milling head is made in the form of a housing 9 with guides 10 and a slider 11 installed in them. A spindle 5 is mounted in the guides 12 of the slider 11 to move along the slider 11 by means of a screw pair 13 connecting them (the drive mechanism of this pair is not shown). The guides 10 and 12 provide the ability to radially move the cutting tool 2.

 Coaxial with the axis of the suspension 6 of the rotary milling head is rigidly connected to the gear sector 14, which is also rigidly connected to the slider 7.

 The gear sector 14 is kinematically connected with the slider 11. This connection is made up of a rotary milling head 4 of a gearbox 15 with a gear wheel 16, a gearbox 17 and a screw pair 18 installed in the housing 9, as well as pairs of non-circular, for example, elliptical gears 19, located between the gearboxes 20, rocker and rack and pinion mechanisms.

 The rocker mechanism consists of a rocker 21, a crank 22 and a slider 23. The rack mechanism consists of a gear rack 24 and a gear wheel 25. The rocker 21 has the ability to move in the guides 10 of the housing 9. The gear rack 24 is rigidly connected to the rocker 21.

The gear ratio of the gearbox 15 with the wheel 16 is determined from the condition of turning the wheel 19 by an angle 2π and rolling the wheel 16 along the gear sector 14 by an angle b _i This ratio is equal to
i _ns = 2π / β _i .
The kinematic transmission parameters between the elliptical wheel 19 and the screw pair 18 are determined from the condition of turning the wheels 19, 20 and crank 22 through an angle of 2 2π, providing the necessary amplitude of the radial movement of the tool 2 and shifting the extreme values of the amplitude of its vibrations closer to points A and B or in the middle of the section processing. These parameters are determined in accordance with the above dependence for m. In this case, l determines the length of the crank 22, P the pitch of the screw pair 18, D the diameter of the initial circumference of the gear 25, i _PB gear ratio of the gear 17, C is the eccentricity of the non-circular (elliptical) gears 19 and 20, v is the current angle of rotation of the wheel 10.

При этом учитывается, что верхние знаки перед коэффициентом С определяют ускоренное движение колеса 20 на начальном и конечном этапах его взаимодействия с колесом 19 (изображено на фиг.4), а нижние знаки - замедленное движение (положение колес 19, 20 должно быть повернуто на 180^o относительно показанного на фиг.4). Также учитывается соответствующее этому смещение экстремальных значений μ(ΔR_i) к точкам А и Б в первом случае и к середине участка во втором случае. Величина коэффициента С может быть принята постоянной для обработки полного профиля рефлектора, что может быть технологически целесообразным из-за исключения смены некруглых зубчатых колес при переходе от одного участка обработки к другому.For each processing section, the relations

It is taken into account that the upper signs in front of the coefficient C determine the accelerated movement of the wheel 20 at the initial and final stages of its interaction with the wheel 19 (shown in Fig. 4), and the lower signs - slow motion (the position of the wheels 19, 20 should be rotated 180 ^o relative to that shown in FIG. 4). The corresponding shift of the extreme values of μ (ΔR _i ) to points A and B in the first case and to the middle of the plot in the second case is also taken into account. The value of the coefficient C can be taken constant to process the full profile of the reflector, which can be technologically feasible due to the exclusion of non-circular gears during the transition from one processing section to another.

 The device operates as follows.

 On the rotary table 3, the billet of the reflector 1 is fixed. Based on the parameters found in accordance with the above dependencies, the device is configured. In this case, by moving the sliders 7 and 8, the axis of the suspension 6 is set around which the rotary milling head 4 is rotated. Then, the kinematic chain parameters are set from the gear sector 14 to the screw pair 18. By means of the screw pair 13, the initial working length of the rotary milling head 4 is set and placed the working edge of the tool 2 at one of the points A (B) of the treated area.

 To process the reflective surface of the reflector 1, the rotary table 3 and the non-circular wheel 19 are rotated around their axes.

The rotation from the wheel 19 through the gearbox 15 is transmitted to the wheel 16, which, rolling around the gear sector 14, rotates the milling head 4 together with the spindle 5 and tool 2 through an angle β _i .

 The rotation from the wheel 19 is also transmitted to the wheel 20 and the associated crank 22. The rotation of the crank through the slider 23 is converted into reciprocating motion of the wings 21 and the rack 24.

 The movement of the rack 24 through the wheel 25, the gearbox 17 and the screw pair 18 is converted into a radial reciprocating movement of the slider 11 along the guides 10 of the housing 9 of the rotary milling head. Together with the slider, the radial reciprocating movement along the rotary milling head 4 receives the spindle 5 with the tool 2.

 Thus, the cutting tool 2, receiving a portable movement along an arc of a circle together with a rotary milling head 4 and relative radial movement along it, processes sections of a reflecting surface on a rotating blank of the reflector 1.

 Reflector processing example.

 Reflector characteristic: theoretical shape of the reflective surface of the reflector; paraboloid of rotation; reflector diameter 2m; focal length 0.66 m; reflector material aluminum alloy AMts GOST 21631-76.

 Fine milling is carried out on a 6M23C13 rotary milling machine equipped with a rotary milling head with the specified system for adjusting and moving the spindle with a cutting tool. An end mill 2223-0506 GOST 20537-75 with a diameter of 40 mm is used as a tool. Processing mode: milling depth 0.2-0.4 mm; feed per mill revolution 1 mm / rev; cutting speed 500 m / min; surface roughness 1.25-1.6 microns.

 When processing the reflecting surface of the reflector in three areas, separated by reference points with coordinates along the abscissa (X) 0; 0.35; 0.7; 1.0 m, the error of the obtained profile does not exceed ± 0.015 mm.

 Using the proposed method and device allows processing the reflective surface of the reflectors close to the paraboloid of rotation with increased accuracy and use such reflectors in antennas with a frequency range of up to 100 GHz and more. The invention is also applicable in mechanical engineering in the processing of products requiring high accuracy of reproduction of curved surfaces. YYY2

Claims (1)

1. The method of obtaining the reflective surface of the reflector of the mirror antenna, in which the billet of the reflector of the mirror antenna is rotated relative to its longitudinal axis, the cutting tool is rotated about its own axis and moved along a circular arc in a plane passing through the longitudinal axis of the workpiece of the reflector of the mirror antenna, characterized in that divide the surface of the workpiece along the generatrix into i sections, move the cutting tool along an arc of a circle in a plane passing through the longitudinal axis of the workpiece ref of the reflector antenna, sequentially on each i-th section, and the circumference parameters are determined from the condition of equal arc lengths of this circle and a theoretical curve, for example, a parabola that defines the profile of the reflector of the mirror antenna in this section, the cutting tool in each i-th section is attached relative to the center circumference radial displacement determined from the expression

where Δ _1i , Δ _{2i are the} maximum values of undercutting and cutting of the theoretical profile of the reflector in the i-th section when moving the cutting tool along an arc of a circle, determined from the condition that the lengths of the arcs of this circle are equal and the theoretical curve;
C _{i is a} coefficient whose value is in the range from 0 to 0.4;
Φ is an angle that varies from 0 to 2π;
2. A device for obtaining a reflective surface of a reflector of a mirror antenna, comprising a rotary table for securing a blank of a reflector of a mirror antenna, a rotary milling head with a spindle and a cutting tool mounted above the rotary table, characterized in that the cutting tool is mounted for radial movement, for which the rotary milling the head is provided with a guide, in which a slider with a guide, in which To move it, a spindle with a cutting tool is installed, a gear sector coaxial to the suspension axis of the rotary milling head is rigidly connected to this axis and kinematically connected to the slider by means of gears and a screw pair installed in the rotary milling head, as well as pairs of non-circular, for example, elliptical, placed between the gearboxes gears, rocker and rack gears, in which the link and the rack are rigidly interconnected, while the gear ratio of the first gearbox between the non-circular gears am and gear sector equals
L _ns = 2π / β _i ,
where β _{i is the} central angle corresponding to the arc of the i-th section,
and the parameters of the kinematic chain between this gear and the slider are determined by the ratio

where μ is the magnitude of the radial movements of the cutting tool;
l the length of the crank rocker mechanism;
P pitch transmission screw pair;
D is the diameter of the initial circumference of the rack gear;
i _pv gear ratio of the second gear;
With eccentricity of non-circular gears;
v the angle of rotation of the drive non-circular gears.

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