RU2232450C1 - Method for producing waveguide sections - Google Patents

Abstract

FIELD: manufacture of complex-shape waveguide sections for microwave, millimetric, and submillimetric wavebands.

SUBSTANCE: proposed method includes pressing of mandrel-mounted round billet by electromagnetic pulse applied in several cycles until desired shape of waveguide channel is attained, this procedure including vacuum annealing at t = 650 - 700 °C for minimum 30 minutes, etching of round billet during spaces between cycles, and fixation of flange on waveguide by using electromagnetic pulse applied upon shaping waveguide channel and flange seating. Depth of magnetic field penetration in metal is found from expression given in description of invention.

EFFECT: enlarged functional capabilities of method.

1 cl, 5 dwg

Description

The invention relates to the field of microwave technology and can be used in the manufacture of waveguide sections of complex configuration of the millimeter and submillimeter wave ranges.

In the known method of manufacturing waveguide sections of complex configuration according to the copyright certificate No. 176964, Н 01 Р 11/00, published in 1966, BI No. 24, the manufacturing process of P- and H-shaped waveguides is based on the galvanic deposition of metal with high electrical conductivity on aluminum composite core with its subsequent chemical etching.

The disadvantage of this method is the low productivity due to the large time spent on the plating of metal on a composite core made by cold pressing of hollow aluminum billets with internal channels, and its chemical etching. In addition, the manufacture of a large number of cores is associated with significant costs and time.

In the known method for the electroforming of complex waveguide assemblies according to the copyright certificate N 145099, H 01 P 11/00, published in 1962, BI No. 4, the walls of the waveguides are made of two layers: the first layer is formed of metal by electrodeposition on a mandrel, and the second layer is made of epoxy resins or other plastics.

The known method also has a low productivity associated with electrodeposition of metal; in addition, the process of removing the waveguide section from the mandrel is a complex technological task, and the resulting waveguide section does not have sufficient mechanical strength.

Thus, the considered methods of manufacturing waveguide sections are characterized by low productivity associated with the galvanoplastic deposition of metal on a core mandrel, and insufficient mechanical strength of the fabricated waveguides.

The noted drawbacks of the methods can be eliminated by replacing the operation of galvanoplastic metal deposition with a core mandrel with alternative technological operations of manufacturing the waveguide wall.

So, for example, in the known method of manufacturing a waveguide element according to copyright certificate No. 1179488, Н 01 Р 11/00, published in 1985, BI No. 34, the formation of the waveguide wall is carried out by pouring into the gap between the mandrel with a profiled working surface and a glass of molten lead then the mandrel is etched with a hot alkali solution.

The known method provides higher process performance, however, the accuracy of the manufacture of waveguide sections of the microwave range does not meet the technical conditions for the product.

In the known method of manufacturing waveguide sections of variable rectangular cross-section according to the copyright certificate No. 680089, Н 01 Р 11/00, published in 1979, BI No. 30, the waveguide sections are obtained by preliminary deformation of a circular tube blank mounted on a model mandrel to obtaining the required parameters in all sections with maintaining a circular shape, and then finally crimp on the mandrel to obtain a given rectangular cross-section. At the same time, a higher productivity of the process is achieved in comparison with the galvanoplastic method of obtaining the waveguide wall and the method of pouring metal into the mold. However, the known method does not provide the desired accuracy in the manufacture of the waveguide section of the microwave range due to elastic-plastic deformations during crimping the workpiece of the waveguide section on the mandrel.

In a known method for the manufacture of waveguide sections of the microwave range according to the article of S.P. Yakovlev, Yu.G. Nechipurenko, E.S. Malenicheva and others. New technology for the manufacture of waveguide sections of the microwave range, magazine "Forging and stamping", 1993, No. 5-6, p.19-20, adopted by the authors for the prototype, as the closest in its technical essence and the achieved effect, the method of manufacturing the waveguide sections includes crimping the tubular workpiece mounted on the mandrel with an electromagnetic pulse in several cycles to obtain a given channel shapewaveguide with vacuum annealing at t = 650 ... 700 ° C for less than 30 min, etching the tubular billet between cycles and forming flanges by machining the outer surface of the tubular billet.

The known method in comparison with a typical technological process can significantly reduce the complexity of manufacturing the part (about ten times) while maintaining the specified accuracy and surface roughness, virtually eliminate the marriage and reduce the cost of manufacturing the waveguide section by obtaining flanges from one workpiece with the waveguide body and increase wear resistance mandrel models.

However, a serious drawback of the known method is its narrow technological capabilities, since it is possible to produce a waveguide section only with a flange whose height does not exceed the dimensions of the waveguide blank.

If the height of the flange exceeds the size of the workpiece, then for its formation by subsequent machining of the outer surface of the tubular workpiece, it is possible to increase the dimensions of the waveguide workpiece, but this increase in size will lead to an increase in the consumption of non-ferrous metal or to the manufacture of the waveguide section from the workpiece with a preformed flange. In this case, the accuracy of channel shaping will significantly decrease due to uneven compression of the blank of the waveguide section on the mandrel along the length of the channel, especially in the area of the preformed flange.

In production conditions, the connection of the prefabricated flange with the waveguide body is carried out by silver soldering, moreover, the installation of the flange is carried out with a guaranteed clearance along the contour, and the soldering process is carried out manually by a gas burner. In this case, expensive silver solder is consumed, and the quality of the solder and the performance of the process do not meet modern technical conditions.

In addition, in the process of high-temperature heating, small pores with flux residues are formed in the brazed joint, which, under the operating conditions of the product, causes corrosion of the surfaces of the waveguide channel and the flange.

Thus, both the manufacturing option of the waveguide section from the workpiece with increased dimensions and the manufacturing option of the waveguide section by soldering a flange on the waveguide body limit the use of the known method and, thereby, narrow its technological capabilities.

The invention is aimed at expanding the technological capabilities of a method for manufacturing waveguide sections. This is achieved by the fact that in the known method of manufacturing waveguide sections, including crimping a tubular billet mounted on a mandrel, with an electromagnetic pulse in several cycles to obtain a given shape of the waveguide channel with vacuum annealing at t = 650 ... 700 ° C for at least 30 min, etching the tubular workpiece between cycles and mounting the flange on the waveguide, fixing the flange on the waveguide is carried out by an electromagnetic pulse after the formation of the waveguide channel and the seat of the flange, and the depth of penetration of magnesium field in the metal is determined from the relation

h ₁ <Δ <h ₁ + h ₂ ,

- глубина проникновения магнитного поля в металл, где h₁ - толщина стенки фланца; h₂ - толщина стенки волновода; ρ - удельное электрическое сопротивление металла; μ _a - магнитная проницаемость; f - частота разряда источника на систему: "индуктор-заготовка".Where

- the depth of penetration of the magnetic field into the metal, where h ₁ is the wall thickness of the flange; h ₂ is the wall thickness of the waveguide; ρ is the electrical resistivity of the metal; μ _a is the magnetic permeability; f is the frequency of the discharge of the source to the system: "inductor-billet".

When fixing a flange, the height of which exceeds the dimensions of the waveguide preform, on the waveguide body mounted on the mandrel with an electromagnetic pulse after shaping the waveguide channel, the accuracy of the previously obtained channel does not deteriorate, and the use of an electromagnetic pulse with the penetration depth of the magnetic field into the metal selected from the relation

h ₁ <Δ <h ₁ + h ₂

allows you to create a reliable connection of parts due to the fusion of the contacting microprotrusions in the mating zone and the joint plastic deformation of the mating surfaces, thereby expanding the technological capabilities of the method, that is, the possibility of manufacturing waveguide sections with a flange whose height exceeds the dimensions of the waveguide blank.

The invention is illustrated by drawings, where in FIG. 1 shows a diagram of the mounting of the flange on the waveguide; in FIG. 2 - section aa of the waveguide section; in FIG. 3, 4, 5 - distribution curves of the magnetic field in the walls of the flange, the waveguide and the mandrel with a thickness of h1, h2, h3, respectively, in the plane of section AA of the waveguide section.

The positions in the drawing indicate:

flange - 1; waveguide - 2; waveguide channel - 3; waveguide mandrel - 4; inductor - 5.

The fastening of the flange 1 on the waveguide 2 is as follows (Fig. 1).

After the channel 3 is formed in the waveguide body 2, a flange 1 is mounted on the waveguide 2 on the waveguide 2, and the waveguide section is placed inside the cavity of the inductor 5, the number of turns of which is selected depending on the frequency of the discharge of the power source to the system: “inductor-billet” at a given penetration depth magnetic field into the metal, while the power in the discharge pulse of the power source should also provide a given value of the deformation of the flange. When the power source is discharged to the inductor 5 under the influence of eddy currents, the mating surfaces of the flange 1 and the waveguide 2 are heated until the contacting microprotrusions melt and plastic deformation of the flange 1 in the direction of the waveguide 2 occurs simultaneously until a reliable connection of the parts is formed.

The mechanism of the process of fixing the flange 1 on the waveguide body 2 under the influence of an electromagnetic pulse from the inductor 5 (Fig. 2) can be shown by considering the flange 1, the waveguide 2 and the mandrel 4 in section AA, as three coaxially located short-circuited turns electrically isolated from each other by a transition contact resistance in the electromagnetic field of the inductor 5 with a variable depth of penetration of the magnetic field into the metal in the radial direction.

When fixing the flange 1 on the body of the waveguide 2 (Fig. 3) with an electromagnetic pulse with a depth of penetration of the magnetic field into the metal by

h ₁ <Δ <h ₁ + h ₂ .

A magnetic field through the wall of flange 1 with a thickness h1 penetrates the wall of waveguide 2 to a depth less than h2 and induces eddy currents in them, which due to the surface effect and proximity effect will flow in the thin surface layers of flange 1 and waveguide 2 and heat them, reducing the mechanical strength of oxide films on the mating surfaces of parts and increase the viscosity of the metal with partial melting of microprotrusions on the contacting surfaces of the flange 1 and the waveguide 2.

At the same time, under the action of electromechanical (ponderomotive) forces, the magnitude of which is proportional to the difference in the magnetic field strength on the external H1 and internal H2 surface of the flange wall and waveguide H3, plastic deformation of the flange 1 occurs in the direction of the waveguide body 2, and when plastic parts come into contact together, they deform effective self-cleaning of oxide films with the union of fused zones, which, after cooling, form a dense weld, which ensures I reliable fastening of the flange 1 to the waveguide body 2.

When fixing the flange 1 to the body of the waveguide 2 (Fig. 4) with an electromagnetic pulse with a depth of penetration of the magnetic field into the metal by an amount

Δ ₂ > h ₁ + h ₂

a magnetic field through the wall of flange 1 with a thickness of h1 and the wall of a waveguide 2 with a thickness of h2 penetrates into the metal mandrel 4 and induces eddy currents in them, which flow in the thin surface layers of the mating surfaces of the flange-waveguide and the waveguide-mandrel, heating them.

However, the heating of the surfaces of the flange 1, waveguide 2 and mandrel 4 will be carried out to a lower temperature, insufficient to melt the contacted surfaces, and the degree of plastic deformation of the flange 1 in the direction of the waveguide 2 body will be less due to a decrease in the electromechanical forces of interaction between the flange 1 and the waveguide 2 and an increase in the electromechanical forces of interaction between the waveguide 2 and the mandrel 4, the value of which is proportional to the difference in the magnetic field strength on the outer and inner surfaces x H1-H2 flange wall; on the outer and inner surfaces of the waveguide wall, on the outer surface of the mandrel H3, preventing these deformations.

As a result of this interaction, a loose fastening of the flange 1 on the waveguide 2 will be obtained without the formation of a weld in the area of the mating surfaces of the parts.

When the power in the discharge pulse of the power source to the inductor increases, microprotrusions will melt on the mating surfaces of the flange-waveguide and the waveguide-mandrel, which, after cooling, form a dense weld and then it will be impossible to remove the mandrel 4 from the obtained waveguide section.

When fixing the flange 1 on the body of the waveguide 2 (Fig. 5) with an electromagnetic pulse with a depth of penetration of the magnetic field into the metal by

Δ ₂ <h ₁

heating of the mating surfaces of the flange and waveguide 2 practically does not occur, however, the degree of plastic deformation of the flange 1 in the direction of the body of the waveguide 2 will be maximum due to the absence of electromechanical forces of interaction between the waveguide 2 and the mandrel 4.

As a result, a dense connection with a large number of micro-shells in the mating zone of the surface of the flange and the waveguide body will be obtained without the formation of a weld, which does not provide reliable fastening of the flange 1 on the waveguide body 2.

An example of the method

The waveguide sections of the microwave range were made. The waveguide sections were fabricated on a MIU-20/2 KhPI magnetic pulse setup (С ₀ = 90 μF, L ₀ = 78 nH, f ₀ = 60 kHz, W ₀ = 20 kJ) in an inductor made of BrB2 beryllium bronze. A block of capacitors was used as a power source with a power in the discharge pulse to the inductor of 20 kJ at an initial voltage of 4.5 kV.

We used tubular billets with an outer diameter of 12.5 mm made of M1 copper with a hole close to the waveguide profile in longitudinal section, obtained by stamping. The waveguide channel was shaped on a steel mandrel with a variable rectangular cross section corresponding to the shape of the waveguide channel with dimensions of 8.1 × 5.9 mm and 1.6 × 0.8 mm over a length of 63 mm.

The waveguide blank on the mandrel was placed on a special device inside the inductor with a number of turns equal to 10, where it was crimped to obtain the desired channel shape with three electromagnetic pulses with vacuum annealing at t = 680 ° C for 30 minutes and etching the workpiece in a copper passivation chemical solution and its alloys (according to TTP AESh 5.071.0.271 in accordance with OST 107.460.092.001-86) between pulses.

Then the outer surface was machined and on the outer surface of the waveguide blank in its end part from the side of the smaller channel, a step was machined with a diameter of 9 mm over a length of 5.5 mm with an annular shaped groove on the cylindrical surface of the step. A copper flange Ml with an outer diameter of 17 mm and a thickness of 5.5 mm was installed on the formed step of the waveguide. The base cylindrical surfaces of the parts were made according to the 8th grade with a surface roughness of 1.6 microns.

The flange was mounted on the waveguide mounted on the mandrel and placed in the inductor by an electromagnetic pulse of the inductor with an energy of 20 kJ per pulse.

Three batches of waveguide sections of 15 pieces each were made at different voltage of the power source, which were determined by the known dependence of the magnitude of the magnetic field penetration into the metal on the frequency of the discharge of the source on the inductor-workpiece system.

For the first batch of waveguide sections, the depth of penetration of the magnetic field into the metal was 6 mm, which corresponded to the condition

h ₁ <Δ <h ₁ + h ₂ .

For the second batch of waveguide sections, the depth of penetration of the magnetic field into the metal was 8.5 mm, which corresponded to the condition

Δ ₂ &gt; h ₁ + h ₂ .

For the third batch of waveguide sections, the depth of penetration of the magnetic field into the metal was 3 mm, which corresponded to the condition Δ ₃ <h ₁ .

The quality of fixing the flange to the waveguide was controlled by visual inspection of the flange and waveguide connection zone from the flange side and the connection zone in longitudinal and cross sections was checked using a BMI-2 microscope. X-ray diffraction analysis was also performed on a DRON-3 diffractometer and scanning electron microscopy on a ROM-100U microscope .

Inspection of the waveguide sections showed that in the first batch after machining the end of the waveguide section, the connection line between the flange and the waveguide was not visually visible, and the connection zones in the longitudinal and cross sections were viewed as a melted thin metal layer on the microscope.

In the second batch of waveguide sections, after mechanical processing of the end face of the waveguide section, the line of connection between the flange and the waveguide was visually clearly visible, and a loose fit of the surfaces of the flange and the waveguide was visible on the microscope.

In the third batch of waveguide sections, the line connecting the flange and the waveguide from the end side was not visually visible, and the microscope showed microracks and micropores in the longitudinal and transverse sections of the connection.

Thus, the proposed technical solution provides the manufacture of a waveguide section with a flange exceeding the dimensions of the blank of the waveguide, which extends the technological capabilities of the method of manufacturing waveguide sections, while increasing labor productivity and reducing the consumption of non-ferrous metal.

Claims (1)

A method of manufacturing waveguide sections, including crimping a tubular billet mounted on a mandrel with an electromagnetic pulse in several cycles to obtain a given shape of the waveguide channel with vacuum annealing at t = 650 ... 700 ° C for at least 30 minutes, etching the tubular billet between cycles and mounting the flange on the waveguide, characterized in that the mounting of the flange on the body of the waveguide is carried out by an electromagnetic pulse after the formation of the waveguide channel and the seat of the flange, and the penetration depth of the magnetic for metal is determined from the ratio h ₁ <Δ <h ₁ + h ₂ , Where

- the depth of penetration of the magnetic field into the metal; h ₁ - wall thickness of the flange; h ₂ is the wall thickness of the waveguide; ρ is the electrical resistivity of the metal; μ _a - magnetic permeability; f is the frequency of the discharge of the source to the system "inductor-billet".

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