RU2289790C1 - Method of making rotor of ball gyroscope - Google Patents

Abstract

FIELD: instrument industry.

SUBSTANCE: method comprises welding thin-walled hemispheres and using the law of variation of yield point of the material depending on temperature with regard to its melting temperature.

EFFECT: enhanced reliability.

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Description

The invention relates to the field of precision instrumentation and can be used in the development of manufacturing technology for ball gyroscopes rotors based on diffusion welding in vacuum of two thin-walled hemispheres with the creation of welding pressure due to thermal interference determined by different values of the thermal expansion coefficients of materials of welded parts and elements of welding equipment.

A known method of manufacturing a hollow rotor of an electrostatic gyroscope [Maleev PI, New types of gyroscopes. Shipbuilding, Leningrad, 1971, pp. 17-18], including the shaping of two hemispheres with an outer diameter of ~ 50 mm, the implementation of an inseparable connection of these hemispheres along the connector planes by fusion welding or soldering, spherical welding and balancing of the rotor. To create the predominant main central axis of inertia during shaping in the equatorial region, the walls of each hemisphere are made thicker than at the pole.

The finishing and balancing of the rotor is carried out with the rotor elongated along the axis of symmetry of the ellipsoid of rotation so that when operating at working revolutions (tens of thousands of revolutions per minute), the rotor transforms into the correct sphere due to centrifugal forces.

The disadvantages of this method are:

1) the relatively low accuracy and reliability of the rotor associated with the presence of a weld (solder) seam located in the equatorial zone of the rotor, which has a strength significantly lower than the strength of the main material (usually beryllium). This causes deviations from the required calculated shape of the ellipsoid during aspheric rotor, as well as unpredictable distortions of the rotor geometry during its transformation into a sphere during operation at working speeds;

2) the functional errors of the rotor, determined by the conductivity of the zone of the welded (soldered) seam having a cast structure that differs from the main material, which creates unequal conditions when the rotor rotates in an electrostatic suspension;

3) the limited capabilities of the manufacturing technology of rotors with a wall thickness of less than 1 mm on the connector, when it is extremely difficult to provide the required level of accuracy in the quality of formation of a welded or soldered seam.

The known manufacturing technology of a thin-walled spherical rotor of a ball gyroscope [RF patent No. 2164665 from 09.11.99, MKI G 01 C 25/00, "Method for manufacturing a ball gyro rotor" / V.Z. Gusinsky, S.M. Osipov, A.G. Shcherbak], in which the machining of the rotor hemispheres with a variable monotonously decreases from the value of h _e in the equatorial plane of the connector to the value of h _p in the pole part, wall thickness and outer diameter D _p , taking into account the allowance Δh for welding deformations and balancing operation . Next, the hemispheres are placed in hemispherical recesses with a diameter of D _p punches installed in the guide cup and made of a material whose thermal expansion coefficient α _p is less than that of the material of the hemispheres α _p , and the diameter D _p is larger than the diameter D _p , the equipment is heated with hemispheres in the vacuum chamber to the welding station of the sealing temperature T _binding exceeding T temperature _to match the diameter D _p and D _n, with the application at the temperature T ₁ ≤T _c axial welding pressure p _from exceeding the yield point beryl Ia and maintained to flow at T welding process _binding at least equal to the temperature of recrystallization of the material hemispheres.

Welding is carried out under conditions in the temperature range (T _s -T _sv ) of the deformation processes with a decrease, ultimately, of the rotor diameter by 0.20-0.40%. The reduction in diameter is taken into account in the allowance for the initial diameter of the hemispheres and does not affect the accuracy of the rotor. The main importance for balancing and accuracy of the rotor is the deviation from the required spherical shape (non-circularity) of the welded billet of the rotor and the symmetry of these deviations (distortion of the sphere) relative to the equatorial plane of the connector (welding zone) and its axis of symmetry passing through the poles of the rotor.

Then, the welded rotor billet is balanced to obtain the product with the required final diameter D _p and the necessary values of axial and radial imbalances.

This technical solution has the following main disadvantages:

1. Limited technological capabilities in the manufacture of rotors of various sizes, for example, with large values of the coefficient K _h = h _e / h _p , which characterizes the degree of thickness variation of the rotor. Actual values of K _h for beryllium hollow rotors of electrostatic gyroscopes can be 4-5. This determines sharply unequal conditions for the deformation of the material of the hemispheres during welding in the equatorial zone and in the pole part and significantly increases both the value and asymmetry of the rotor shape distortion, which, in turn, complicates the process of balancing high-precision rotors (final shape error ≤0.02 μm )

2. Difficulties in the manufacture of high-precision rotors, due to the specific features of the materials used, in particular, the material most suitable for ball gyroscopes rotors, such as beryllium, which is characterized by anisotropy of properties determined by the technology for obtaining the initial blanks. The anisotropy of the temperature coefficient of linear expansion (TEC) and the elastic modulus have the greatest influence on manufacturing technology. In diffusion welding according to the above scheme with the load applied to the entire spherical surface of the rotor, when the welding pressure diagram is stresses radially oriented to its center, different values of the thermal expansion coefficient and elastic modulus of the rotor hemispheres cause uncertainty in the process of plastic deformation of the hemispheres and asymmetry of distortions of the rotor shape.

3. Technological difficulties in reducing the degree of variation in the thickness of the hemispheres due to the allowance Δh on the outer diameter D _p , since this does not fully ensure the conditions of minimal rotor deformations that correspond to acceptable ones, because to get the values

a significant increase in rotor diameter is required. In this case, an excessively large value of Δh (more than 1.5-2 mm) determines either the greater complexity of the subsequent removal of the allowance in a three-spindle lapping device, or the low accuracy of machining the rotor on a lathe using a circular cutter, where it is possible to lose the center of the sphere due to the lack of a base surface (in fact, the basic outer sphere is the surface being machined) with inevitable reinstallations of the rotor in the mandrel.

4. There are restrictions on the welding of rotors of various modifications (with different values of the coefficient of different thicknesses K _h ), since for each rotor there will be its own allowance Δh, which allows minimizing K _h to an acceptable value. This determines the possible deviations from the nominal diameter D _p within ± 0.5 mm, which leads to the need to either produce new options for complex expensive equipment with different values of D _p , or to adjust the welding mode, which is not always possible.

As a prototype for the largest number of common essential features was adopted a method of manufacturing a thin-walled rotor of a ball gyroscope [A.G. Scherbak, V.G. Kedrov. "The technology of precision diffusion welding in precision instrumentation" - St. Petersburg: State Research Center of the Russian Federation - Central Research Institute "Elektropribor", 1996, p. 70-71, 80-82], in which at the stage of forming on the outer side of each hemisphere of the rotor perform an annular flange, one of the end surfaces of which coincides with the plane of the hemisphere connector, and the height 1/2 · L ^d _about is determined from the expression

where D _n = D _p - outer, and D _ext - inner diameters of the rotor.

Next, the welded hemispheres with a gap Δ ^d _o (for evacuating the inner cavity of the rotor) are installed in the welding punches, the punches are fixed to each other by force longitudinal elements of the covering clips in the form of couplers, which are a set of identical rods uniformly and at the same distance from the axis of the punches distributed around the circumference using attachment points. The material of the couplers has a coefficient of thermal expansion less than the materials of the punches and welded hemispheres.

The equipment is loaded into the welding chamber, the chamber is evacuated to the required degree of vacuum, and the equipment with the hemispheres is heated to the welding temperature. During heating due to various thermal expansion of the material of the screeds on the one hand and the materials of the punches and welded hemispheres on the other hand, after the clearance Δ ^d is reduced to zero ^, a thermal interference arises, which ensures the creation of a welding pressure applied to the flanges of the hemispheres. The calculation of the required value of the welding pressure is based on the known expressions [see G.V. Konyushkov, Yu.N. Kopylov "Diffusion welding in electronics". Energy, M., 1974, p.73], taking into account the values of the coefficients of thermal expansion, linear dimensions and elastic moduli of the parts to be welded and snap-in assemblies.

The welding pressure of the calculated value in combination with the welding temperature creates the conditions for the implementation of the welded joint. After the welding operation, the flanges are trimmed, the rotor is trimmed and balanced.

Given the tendency to reduce the dimensions of the annular flanges (to a height of 4-6 mm with a width of 2-3 mm), this technology from the point of view of material consumption can be more effective than that presented in the previous analogue, where an allowance for rotor diameter is required to reduce the value of K _h (i.e., the entire outer spherical surface) is also within 2-3 mm.

The disadvantages of this method are the relatively low quality of the welded joint and the relatively low accuracy of the manufactured rotor, which is determined by the following factors:

1) A similar diffusion welding technology at the assembly stage involves the individual fixation of each screed with respect to the punches by means of a mounting unit (for example, by screwing nuts on the threaded parts of the screeds). This determines a different amount of the initial interference fit of each screed. Different initial tightness, as well as possible backlash in the mounting units (for example, thread error) lead to the fact that for each screed (total 4 ... 12 pieces) in the initial period there will be a different proportion of the total pressure that occurs during heating during welding due to various thermal expansion of tooling elements and parts. The different force transferred by each of the couplers to the punches will cause the welding load to be uneven along the perimeter of the joint zone. This determines the asymmetry of the welding load with respect to the weld and the various conditions in which its different sections are located, which causes uneven deformation of the flanges and reduces the quality of the weld in terms of the equivalence of its characteristics (for example, strength) over its entire area.

2) The above uneven distribution of the welding load in the contact zone of the parts to be welded can lead to asymmetric deformation of the parts during welding, as well as to their skew and radial displacement from the original orientation specified during assembly, which reduces the accuracy of the welded product.

3) During the welding process, with an increase in the welding load, the play on different couplers can be removed in different ways, which leads to an uncertain distribution of the welding pressure of the thermal interference between these couplers and, as a result, to an uncertainty in the orientation of the resulting welding load, the direction of which can arbitrarily change, which also leads to a decrease in the quality of the welded joint and the accuracy of the product.

4) It is possible to regulate the moment of the beginning of deformation of the welded parts only approximately by changing the gap Δ ^d _about , while the optimal conditions are the beginning of the deformation of the welded parts at a temperature in the range from 0.9 · T _sv to T _sv . Moreover, the uniformity of deformations, as mentioned above, this technology does not provide.

Obviously, the indicated errors and deviations from the required configuration of the welded rotor lie within hundredths of a millimeter. However, for rotors of ball gyroscopes, the permissible deformations and their symmetry should be at the level of micrometer units, since the final rotor accuracy (shape and imbalance) is tenths and hundredths micrometer fractions.

The objective of the invention is to improve the quality of the welded joint and the accuracy of the rotor of a ball gyroscope.

According to the invention, the problem is solved in that the material of the couplers is selected with a melting temperature T ^s _pl greater than the melting temperature T ^d _{pl of the} parts to be welded, while the total area S ^{from the} cross section of the couplers is determined from the expression:

where σ ^d _t and σ ^c _t are the yield strengths of materials of welded parts and screeds, respectively, at T = 298 ° C,

S ^d - the cross-sectional area of the welded parts,

T _St - welding temperature,

K is a coefficient making up a value (0.9 ... 0.95),

and the value of the welding pressure is selected from the condition:

σ ^d _t (T ₁ ) · S ^d > P _sv (T ₁ )> σ ^s _t (T ₁ ) · S ^s ,

where σ ^d _t (T ₁ ) and σ ^c _t (T ₁ ) · S ^s - yield stresses of materials of welded parts and screeds, respectively, at temperature T ₁ ,

P _St (T ₁ ) - welding pressure at a temperature T ₁ ,

T ₁ - process temperature, component (0.7 ... 0.85) from T _St.

The invention is illustrated by drawings, in which Fig. 1 shows a general assembly diagram of hemispheres in a welding tool, in Fig. 2 - the dependences of yield strengths σ _tt and critical pressures P _cr = σ _tt · S on temperature for the parts to be welded and ties, 3 - time dependences of the main parameters of the welding process.

In figure 1, 2 and 3 are indicated:

1, 2 - welded hemispheres;

3, 4 - annular flanges made on the outside of the hemispheres 1 and 2;

5, 6 - welding punches mounted on flanges 3 and 4 of hemispheres 1 and 2;

7, 8 - couplers of the enclosing tool holder, through which the punches 5 and 6 are rigidly fixed to each other;

9, 10, 11 and 12 - fixing nodes for fixing the screeds 7 and 8 relative to the punches 5 and 6;

13 - dependence of the critical pressure P ^d _cr = σ ^d _tt · S ^d , at which the flanges 3 and 4 of the welded hemispheres 1 and 2 begin to deform, on temperature (σ ^d _tt is the yield strength of the material of parts at a given temperature and S ^d is the transverse area sections (contact zones) of flanges 3 and 4 of hemispheres 1 and 2;

14 - dependence of the critical pressure P ^with _cr = σ ^d _ttt · S ^s , at which the screeds 7 and 8 begin to deform, on temperature (σ ^s _tt is the yield strength of the screed material at a given temperature and S ^s is the total cross-sectional area of the screeds 7 and 8);

15 - the dependence of the change in yield strength σ ^with _TT material of the screeds 7 and 8 on temperature;

16 - temperature change of the yield strength σ ^d _{tt of the} material of the welded hemispheres 1 and 2;

17 - dependence of the process temperature T _p on time t;

18 - dependence of the magnitude of the welding pressure P _s determined by thermal interference, on time t with a change in temperature T _p ;

19 - dependence of the strain ε _{from the} screeds 7 and 8 on time t with a change in temperature T _p ;

20 - dependence of the strain ε _{d of} flanges 3 and 4 of hemispheres 1 and 2 on time t with a change in temperature T _p ;

21 - change in the gap Δ ^d between the flanges 3 and 4 of the hemispheres 1 and 2 from time t with a change in temperature T _p ;

22 - dependence of the critical pressure P ^with _cr = σ ^s _TT · S ^s (1) for one screed from time t with a change in temperature T _p ;

23 - dependence of the critical pressure P ^d _cr = σ ^d _tt · S ^d , at which the flanges 3 and 4 of the welded hemispheres 1 and 2 begin to deform, on time t with temperature T _p ;

24 - dependence of the critical pressure P ^with _cr = σ ^c _TT · S ^c , at which the ties 7 and 8 begin to deform, on time t with temperature T _p ;

t _c is the moment of coupling of the hemispheres 1 and 2 at a temperature T _s when the gap Δ ^d becomes equal to zero;

t _p - time point of equality of critical pressures P _cr (T _p ) = P ^d _cr (T _p ) = P ^with _cr (T _p ) at a temperature T _p ;

P is the intersection point of the dependencies 23 and 24, corresponding to the time t _p and temperature T _{p the} equality of critical pressures of parts and screeds;

t ₁ is the point in time corresponding to the condition σ ^d _t (T ₁ ) · S ^d > P _sv (T ₁ )> σ ^s _t (T ₁ ) · S ^s , at a temperature T ₁ less than T _p ;

t _n and t _k - the time of the beginning and end of the isothermal exposure of the welded hemispheres 1 and 2 at a welding temperature T _St (welding time);

Δ ^d _about - the initial gap between the hemispheres 1 and 2;

1/2 · L ₀ ^d - the height of the working part of each of the flanges 3 and 4;

l / 2 · L ₀ ^p - the height of the working part of the punches 5 and 6;

L ^with ₀ - the length of the working part of the ties 7 and 8;

00 ₁ - axis of the welding tool;

The process of diffusion welding of parts in accordance with the proposed method consists in performing the following combination and sequence of technological operations.

1. The main element of the technology is the choice of the material of the screeds 7 and 8. Formulating the requirement for the material of the screeds, we can say that a necessary initial condition is the nature of the change in the plastic characteristics of the materials of the screeds and welded parts with an increase in the process temperature so that less plastic resistance screeds rendered deformation, and after that the values were welded parts. This will ensure at the initial stage of heating (after the gap Δ ^d becomes equal to zero) preferential deformation of the screeds and, as a result, the equalization of the load distributed between them. At the second stage (upon reaching the required temperature close to T _b ), preferential deformation of the welded parts will take place during stabilization of the welding pressure evenly distributed across all the ties, which is required for the course of welding processes.

When designating resistance to deformations by the concept of critical pressure P _cr equal to the product of the yield strength of this material used in the calculation of diffusion welding regimes σ _tt at a given temperature and the cross-sectional area of this element (i.e., P _cr = σ _tt · S), indicated above the scheme can be implemented by ensuring the intersection at a given point (point P - FIGS. 2 and 3) of the dependencies R ^d _cr = R ^d _cr (T) and P ^c _cr = P ^c _cr (T), which will take place at a certain equilibrium temperature T _p at time t _p (figure 3). Moreover, at temperatures lower than the value of T _p (to the left of the point P - figure 3), there should be a ratio of P ^with _cr <R ^d _cr , and at temperatures higher than T _p (to the right of the point P - figure 3) - the ratio R ^s _cr > R ^d _cr . In this case, the requirement T _p <T _St.

The choice of material that provides the specified condition for the intersection of the dependencies P _cr = P _cr (T) should be made taking into account the values of yield strengths σ _{t of the} materials of the ties and welded parts and the ratio of the cross-sectional areas of these nodes S ^c and S ^d .

It can be shown that the initial ratio of σ ^d _t and σ ^c _t (yield strength under normal conditions is 298 K) and the nature of dependencies 15 and 16 (Fig. 2) are not critical, as these curves can be moved to the position of curves 13 and 14, respectively (FIG. 2), by varying the ratio of the areas S ^c and S ^d , i.e. they can be shifted lower or higher to the required position, together ensuring the fulfillment of the above requirements:

- P ^with _cr <P ^d _cr at temperatures lower than the value of T _p ;

- P ^with _cr > R ^d _cr at temperatures greater than T _p ;

- T _p <T _St.

A similar diagram is presented in figure 3 for dependencies 22, 23 and 24.

To fulfill the above relations, it is necessary to more intensively decrease the value of σ ^d _tt · S ^d in comparison with the rate of decrease of σ ^c _tt · S ^c with increasing temperature, as shown in FIG. 2.

In other words, for each temperature range ΔТ, the relation ∂ (σ ^d _tt ) / ∂T> ∂ (σ ^d _tt ) / ∂T or

Obviously, these conditions are provided by two factors:

1) the fulfillment of the relation

where from

2) and the excess of the melting temperature of the power elements T ^with _PL the melting temperature of the welded parts T ^d _PL :

since in accordance with the known [see Kochergin A.K., Shestakov A.I. "On the relationship between pressure and temperature in press and diffusion welding." - Sat Welding, Shipbuilding, 1968, No. 11, p.118-120] expression

a more rapid decrease in the yield strength σ _tt at a given temperature with an increase in the current process temperature T _p takes place for materials with a lower T _pl .

Considering factors 1) and 2) together, it can be shown that their support is unambiguously related to the task of intersecting the dependences of the critical pressures of the screeds P ^with _cr and welded parts R ^d _cr from temperature, i.e. dependencies P ^with _cr = P ^with _cr and P ^d _cr = R ^d _cr (T), at point P at a temperature of T _p (figure 2 and 3).

Based on the equality of critical pressures for screeds and welded parts at a temperature T _p at point P, we can write:

or taking into account expression (5):

and given the need, as indicated above, the fulfillment of the condition T _p <T _St , at sufficiently close values, i.e. asking

where K is a coefficient equal to (0.9 ... 0.95),

expression (7) can be written as:

whence follows

Obviously, the choice of the value of S ^c in accordance with the expression (10) under the condition T ^with _pl > T ^d _{pl is} carried out when the relation (3) - S ^c <σ ^d _t · S ^d / σ ^c _t ,

since the part of expression (10), which is a factor for σ ^d _t · S ^d / σ ^s _t , is less than unity:

what can be proved, assuming that the value of T _St is part of the temperatures T ^d _PL and T ^with _PL .

moreover, m> n, since T ^d _pl <T ^with _pl by definition (expression 4),

and substituting the values (12) in the left side of the expression (11), we have:

and since the numerator (1-m) of the fraction is less than the denominator (1-n)

due to the fact that m> n, then S ^c <σ ^d _t · S ^d / σ ^c _t .

Thus, the choice of the cross-sectional area value of the screeds 7 and 8, based on expression (10), when choosing the material of the power elements from the condition T ^d _pl <T ^s _pl provides the above required ratio of the critical pressure dependences of the screeds (P ^c _cr ) and welded parts (R ^d _cr ) at various stages of the process:

- P ^with _cr <R ^d _cr at temperatures T _p <T _p = (0.9 ... 0.95) T _s and

- P ^with _cr > R ^d _cr at temperatures T _p > T _p .

2. Assemble the parts to be welded 1 and 2 in a snap by installing punches 5 and 6 on the end surfaces of the flanges 3 and 4, which are rigidly fixed to each other by means of ties 7 and 8, corresponding to the above conditions in terms of S ^c and made of a material corresponding to the ratio of T ^d _pl <T ^with _pl . Rigid fixation of the punches 5 and 6 is carried out by means of fasteners 9, 10, 11 and 12. In FIG. 1, as an example, only two ties 7 and 8 are shown, diametrically spaced around the circumference of the punches 5 and 6 and installed in the holes provided in these punches. Obviously, the cross-sectional area of each of the identical screeds 7 and 8 in this case is 1/2 · S ^c. The fasteners 9, 10, 11 and 12 in a particular case may be nuts screwed onto the threaded part provided at the ends of the ties 7 and 8. Usually 4 to 12 ties are used in order to more widely disperse the load around the perimeter of the weld .

In the real version, in contrast to the schematic image in figure 1, the flanges 3 and 4 of the parts to be welded 1 and 2 can have a complex configuration with different cross-sectional areas S ^d in different areas. Obviously, for the calculation by expression (10), the minimum value of S ^d is taken, which, as a rule, is structurally set in the welding zone, where the presence of deformation is a necessary factor in the welding process. As indicated above, the required value of the welding force P _s determined by thermal interference at a process temperature T ₁ equal to (0.7 ... 0.85) · T _s (i.e. T ₁ <T _p ) must exceed critical pressure P ^with _cr (T ₁ ) of the power elements and, at the same time, be less than the critical pressure P ^d _p (T ₁ ) of parts 1 and 2 at this temperature T ₁ . The value of P _{St is} calculated according to known dependencies (see the link in the description of the prototype method), including linear dimensions (the height of the parts to be welded L ^d _o , the height of the punches L ^p _o , the length of the working part L ^c _{o of the} ties, the cross-sectional area S ^c and S ^d and physical and mechanical properties of materials (thermal expansion coefficients and elastic moduli of the parts to be welded, punches and screeds). Since the screed material and the values of S ^c and S ^{d are} already determined at the first stage of the technological calculation, the required welding pressure is specified by the selection of the values of L ^p _o , S ^c and L ^с _o , which is quite simple in practical implementation, since there is a fundamental factor that the thermal expansion coefficients of the materials of the welded parts 1 and 2 and punches 5 and 6 exceed the coefficient of thermal expansion of the material of the ties 7 and 8.

3. The assembled welding equipment with parts 1 and 2 is loaded into the vacuum chamber of the welding installation, the chamber is pumped out to the required vacuum and a smooth rise in the process temperature T _p begins _. With increasing temperature T _p (dependence 17 in figure 3) from time t _c , when the gap Δ ^d becomes equal to zero, a smooth increase in the welding pressure begins (curve 18), while the critical pressures P _{cr of the} screeds decrease — dependence of 24 — and the welded parts — dependence of 23. Under normal conditions (298 K), the relation R ^d _cr > P ^with _cr - 3, one-quarter to the rate of decrease of P ^d _kr (curve 23) will be substantially higher. It can be assumed that during the heating process at the initial moment, the actual distribution of the arising force P _s between the couplers 7 and 8 will be uncertain.

Strictly speaking, at this stage, the localization of pressure on one of the screeds can already lead to its preferential deformation and equalization of pressure between all screeds even at a temperature lower than T ₁ . However, on reaching the temperature T ₁ at time t ₁ (Figure 3) will occur first equation, and then the excess of the welding pressure P _binding ^to the critical pressure P _cr of all ties. Those. guaranteed deformation of the screeds will occur (dependence 19) with predominant deformation of the more stressed ones, on which even a small load localization takes place. This will lead to a uniform distribution of pressure between the ties 7 and 8 and, ultimately, to the fact that the resulting pressure P _sv will coincide with the axis OO _{1 of the} tooling and the welded parts. Moreover, at this stage of the process of deformation of the welded parts does not occur, because the relations R ^d _cr > P ^with _cr and R ^d _cr > R _St.

A further increase in temperature (curve 17 in Fig. 3) leads to an equalization of the values of P _cr (T _p ) at a temperature T _p at time t _p , and then to the fact that at T _p > T _{p the} value of P ^d _cr becomes less than P ^s _cr , and the welding pressure P _s becomes greater than the value of P ^d _cr .

The beginning of the isothermal exposure of parts at time t _n upon reaching the temperature T _s corresponds to a steady excess of P _s values of R ^d _cr . And since at this stage R ^d _cr <R ^s _cr , there will be a predominant plastic deformation of the flanges 3 and 4 of the welded hemispheres 1 and 2, which, in combination with the process temperature equal to T _b , will provide optimal conditions for the flow of welding processes. Moreover, the welding process will be carried out with a stable uniform distribution over all the ties and the perimeter of the weld of the welding load, the resulting direction of which will coincide with the axis OO _{1 of the} welded parts and accessories. In this case, the option of non-deformable punches is considered, which fully corresponds to the actual practice and greatly simplifies the calculation and control of the welding process.

It is obvious that in Fig. 3, the dependence of 18 the welding pressure P _s on the process temperature T _p is of a qualitative nature and does not take into account scale factors. Strictly speaking, after the start of deformation of the screeds (time t ₁ at T ₁ ), the increase in pressure P _s will not synchronously increase the temperature due to the fact of deformation. In addition, it can even decrease with the beginning of the deformation of parts during the welding process. This can be compensated by various technological methods, which for the essence of the present invention are not fundamental.

Figure 3 (also without taking into account the scale factor) shows the nature of the change in the magnitude of the strains ε _s (dependence 19) and ε _d (dependence 20). In the time interval t ₁ -t _{p there} is a more intensive increase in ε _s than in the interval t _p -t _n when most of the deformations occur on the flanges - ε _d . Upon reaching T _st in the time interval t _n -t _{k, the} growth of strains ε _s and ε _{d is} insignificant (although ε _d grows somewhat faster), because R ^d _cr at this stage is less than P ^with _cr . In this case, with known assumptions, the strains ε _c and ε _d can be considered as having a constant speed and corresponding to the steady-state stage of high-temperature creep under constant stress.

4. At the end of the welding process, the equipment with parts is cooled to room temperature, the chamber is depressurized and the welded product is removed.

Thus, the diffusion welding process was implemented with the creation of welding pressure due to thermal interference determined by various coefficients of thermal expansion of the equipment materials and the welded parts, which ensures at the first stage of the process when heated to a temperature T _p = (0.9 ... 0.95) · T _sv alignment of the distribution of welding stresses on the screeds covering the holder of welding equipment due to their preferential deformation, which determines the perpendicularity of the resulting load to the plane of the weld, and at the second stage - upon reaching T _p - preferential deformation of the welded parts with stabilized equal participation of all couplers in creating and maintaining uniform welding pressure, which creates the most acceptable conditions for the flow of welding processes. This improves the quality of the welded joint and the accuracy of the rotor, which is due to:

1) An exception to the uneven distribution of the welding load on the couplers, determined by the errors in fixing the couplers during assembly of the welding equipment.

2) An exception to the asymmetry of the welding load relative to the parts to be welded, since possible asymmetry is eliminated in the first stage, when there is no deformation of the parts. At the stage of deformation of parts (welding stage), the deformation of the screeds is minimized, which determines the stable uniformity of the load. This determines guaranteed symmetrical deformation of parts without distortions and increases the accuracy of the welded assembly.

3) By eliminating the uncertainty associated with the arbitrary nature of the change in the direction of the load applied to the parts to be welded, since the removal of the fixing backlash and the elimination of assembly errors is guaranteed by the fact that the welding pressure P _s exceeds the strain resistance pressure P ^s _cr with respect to the total total cross-sectional area of the ties . Those. guaranteed deformation (in the range from units to tens of micrometers) of all screeds is deliberately ensured, which completely eliminates all backlash and tool assembly errors. Moreover, the processes of deformation of screeds and parts are spaced in time, and the deformation of screeds is carried out earlier - at a given point in time at a given temperature, which is ensured by the calculation of the welding process. Ultimately, the controllability of the welding process is increased, which improves the quality of the joint and the accuracy of the welded assembly.

Thus, the task is solved in that it is ensured by unity, a stable relationship, compliance with the principle of necessity and sufficiency of significant distinguishing features:

- the choice of material screeds having a melting point greater than the material of the welded parts;

- calculation of the cross-sectional area of the screeds, based on the condition for the intersection of the temperature dependences of the strain resistance (critical pressures) at a temperature T _p = (0.9 ... 0.95) · T _s , taking into account the greater degree of decrease in the value of resistance to deformation (critical pressure ) parts to be welded than screeds as the process temperature rises;

- regulation of the welding pressure, determined by thermal interference by changing the length of the working part of the screeds and the height of the punches, based on the fact that at a temperature T ₁ = (0.7 ... 0.85) · T _{sv the} welding pressure should be less than the deformation resistance of the parts to be welded, and more than the deformation resistance of the screeds.

At the Central Research Institute "Electropribor", the proposed method was tested in the manufacture of thin-walled spherical rotors of beryllium rotors of electrostatic gyroscopes with obtaining positive results. At the same time, KN 29 kovar was used as the material of the couplers in the welding of beryllium rotors, and 12Kh18N10T chromium-nickel steel was used as the punches material. The proposed welding scheme ensured the deformation of the screeds ε _c = 0.080-0.085 mm during deformation of the uniaxial compression of the flanges ε _{d of the} order of 0.02 mm, and up to 0.070 mm from the deformation ε _{s was} carried out at the stage of heating to temperature T _p . The uniformity (symmetry) of the specified sediment deformation ε _d was ± 0.002 mm.

Currently, technical documentation is being developed for using the proposed diffusion welding method in serial production of various modifications of beryllium rotors of electrostatic gyroscopes.

The technical and economic efficiency of the invention is to improve the quality of the connection and the accuracy of the welded units, which increases the reliability of the products and improves the operational and functional characteristics of the gyro devices in general.

It is not currently possible to determine the economic effect due to the lack of statistically based comparative and initial data.

Claims (1)

A method of manufacturing a ball gyroscope rotor, comprising shaping hemispheres with outer annular flanges, diffusion welding of hemispheres with creating welding pressure due to different values of thermal expansion coefficients of materials of welded parts and welding tool assemblies by assembling parts in welding punches placed on the outside of the flanges and fixed between a snap ties embracing holder by heating with a snap parts in the welding chamber to a sealing temperature T _{communication} with iso ermicheskoy delayed for flow of welding processes subsequent trimming flanges, debugging and rotor balancing, characterized in that the tie material is selected having a melting temperature T ^with _mp greater than the melting temperature T ^g _pl welded parts, the total area S ^c of the cross sectional screeds determined from the expression:

where σ ^d _t and σ ^c _t are yield stresses of materials of welded parts and screeds, respectively, at T = 298 ° С; S ^d - the cross-sectional area of the welded parts; T _St - welding temperature; K is the coefficient making up the value (0.9 ÷ 0.95), and the value of the welding pressure is selected from the condition: σ ^d _t (T ₁ ) · S ^d > P _sv (T ₁ )> σ ^s _t (T ₁ ) · S ^c , where σ ^d _t (T ₁ ) and σ ^c _t (T ₁ ) · S ^c - yield stresses of materials of welded parts and screeds, respectively, at temperature T ₁ .

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