RU2113072C1 - Method for concentrating current on working surface of inductor - Google Patents

Abstract

FIELD: high-frequency current engineering and associated devices; induction build-up of parts for all industries. SUBSTANCE: for concentrating current on working surface of inductor, its nonworking surfaces are ribbed by means of wire soldered onto them; parameters of ribbed surfaces satisfy condition a > 0, b > 0, c > 0, where a is rib height; b is rib width; c is rib-to-rib distance, remembering that 0 is assumed as working surface roughness. EFFECT: enlarged functional capabilities. 7 dwg

Description

 The invention relates to the field of technology and devices of high frequency currents and can be used for induction surfacing of products in all sectors of the economy.

Known methods of concentration of current in an induction wire:
- ring effect (counter currents), in which currents of the opposite direction, flowing in adjacent conductors, are displaced, concentrating on the surfaces of the inductor branches closest to each other (see book A.E. Slukhotsky, S. E. Ryskin. Inductors for induction heating. L .: Energy, 1974, p.17);
- the effect of parallel currents, which consists in the concentration of displaced high-frequency currents of one direction on the most remote surface of the conductor (see the book. EN Nikolaev, IM Korotin. Heat treatment of metals with high-frequency currents. M: Higher school, 1984 , p. 62, Fig. 46, b);
- the effect of the magnetic circuit allows you to influence the current concentration by changing the distribution of the induction current on the surface of the inductor (see book. A.E. Slukhotsky, S.E. Ryskin. Inductors for induction heating. L .: Energia, 1974, p.106).

 However, analyzing the operation of various effects, the developers of the Engineering Center "Alloy" through the development of new types of inductors came to the solution of the question of the concentration of electromagnetic energy in the direction given by the technology.

The known method of one-sided continuous sequential induction surfacing [1], which consists in the fact that the induction wire in cross section is made in the form of a droplet facing a narrow part to the surfaced surface, the axis of symmetry of which is inclined to the said surface at an angle of 25-115 ^o C, and the axis the symmetry of the drop-shaped cross section of the induction conductor is inclined to the inclined surface at an angle of 45 ^o .

 The disadvantage of this method is that, observing the rule of the ring effect, the applicant was able, due to the redistribution of energy in the cross section of the working coil, to concentrate the currents along the pattern of the conductor on the working and rear sides of the cross section, so a significant part of the current remains on the idle surface, and not on the specified sections of the inductor, which reduces the effect of the interaction of the inductor with the part and increases the heating time of the latter.

 For the prototype, a method was selected for concentration of current on the working surface of the inductor [2], in which a loop water-cooled current lead is performed with additional electrically conductive plates welded to the current lead in the transverse direction.

 However, the disadvantage of the prototype is that the ribs of the plate are welded to the current guide in the transverse direction, and the thickness of the plates should be at least twice the depth of penetration of current into the plate material. This circumstance determines the limited use of this method of current concentration only for plastic deformation and heat treatment, but cannot be used for induction surfacing in a wide range, which reduces the technological capabilities of the method as a whole.

 The purpose of the invention is the expansion of technological capabilities with the efficient use of high frequency currents.

 This goal is achieved by the fact that with the known method of concentration of current on the working surface of the inductor, in which the path of the passage of high-frequency current on non-working surfaces of the inductor is lengthened by forming them in the form of ribbed surfaces in the transverse direction relative to the current flow, and the ribbed surface is formed of wire on non-working surfaces of the inductor, while the parameters of the ribbed surfaces satisfy the condition: a> 0, b> 0, c> 0, where a is the height of the rib; b is the width of the ribs; c is the distance between the ribs, taking into account that the roughness of the working surface of the inductor is taken as zero.

 In FIG. 1 shows a one-way inductor; in FIG. 2 is a section AA in FIG. one; in FIG. 3 - section BB in FIG. one; in FIG. 4 is a section BB of FIG. one; in FIG. 5 - ring inductor for surfacing the inner surfaces of cylindrical products; in FIG. 6 is a section GG in FIG. 5; in FIG. 7 - section FJ in FIG. 6.

 The proposed method is implemented as follows.

 Depending on the product subject to induction surfacing, an inductor is made: for flat surfaces - one-sided (see Fig. 1), for cylindrical surfaces - annular (see Fig. 5). Regardless of the shape, each inductor has a working surface (D) and a non-working one (E). The working surface D during operation of the inductor is at a gap value h from the heated product (see Fig. 2, 7).

где
Z - полное сопротивление;
R - активное сопротивление;
X - реактивное сопротивление.In order to concentrate the currents on the working surface D of the inductor, it is necessary to redistribute the currents in the conductor using the difference in the total resistances

Where
Z is the impedance;
R is the active resistance;
X is the reactance.

Surfaces D and E are a parallel electrical circuit, where surface E has (Z ₁ ) and surface D (Z ₂ ).

Из этого условия видно, что чем больше сопротивление, тем меньше ток.We use the first Kirgoff rule

From this condition it is seen that the greater the resistance, the less current.

 Thus, we create conditions of lower current resistance on the conductor from the side of the heated part (surface D).

где
ρ - удельное сопротивление материала;
R - активное сопротивление;
l - длина пути тока;
S - поперечное сечение токопроводящего слоя.It is known that

Where
ρ is the resistivity of the material;
R is the active resistance;
l is the current path length;
S is the cross section of the conductive layer.

 To increase the resistance R on the non-working surface E (see Fig. 2, 3), it is necessary to increase the path of the HDTV along non-working surfaces. For this, non-working surfaces are formed in the form of a ribbed surface by rolling (see Fig. 2) or surfacing of the wire (see Fig. 7) in the transverse direction of the relative current flow. In connection with this, there is a redistribution of current on the surfaces of the inductor; it, as in a magnetic circuit, begins to concentrate on a surface where the impedance is less, i.e. on the surface (D).

 Thus, for any surface roughness, the length of the current path increases and, therefore, the resistance increases, and the current tends to redistribute to the section with lower resistance, i.e. on the working surface D.

 Denoting the parameters of the ribbed surface by: a is the height of the rib, b is the width of the rib, c is the distance between the ribs (see Fig. 2, 7), the optimal conditions for the passage of current with increasing its path should be satisfied, under which a> 0, b> 0, c> 0, taking into account that the unevenness of the working surface is taken as zero.

 In addition, a second variant of current concentration on the working surface D. was discovered.

разработчики использовали материал с удельным сопротивлением, например сталь X18H9T, ρ = 0,14 и выполнили из нее нерабочие поверхности, а из меди c = 0,017 - рабочую поверхность. Таким образом, опять наблюдалось вытеснение токов на рабочую поверхность D. Причем толщина токопроводящих поверхностей должна быть не менее глубины проникновения тока.Again, based on the condition

the developers used a material with resistivity, for example, X18H9T steel, ρ = 0.14 and made non-working surfaces from it, and c = 0.017 made of copper, the working surface. Thus, current displacement to the working surface D was again observed. Moreover, the thickness of the conductive surfaces should be no less than the current penetration depth.

 Example 1. Surfaced flat blank of material 45. Dimensions 1000 x 800 mm, thickness 20 mm. An inductor was made of M3 copper, a 7x4 square tube, 1 mm thick = 200 mm. By means of a wire with a diameter of 2.5 mm, it was soldered with a pitch of 2.5x2.5 mm onto non-working surfaces along the length L = 100 mm on the branches of the inductor, while leaving one of the surfaces of the inductor, called the working one, open (see Fig. 2, 3, 4 ) facing the weldment.

In our work, we used a VCG generator 9-6 / 0.44 with an operating frequency of 440 kHz, the gap between the inductor and the part h = 4 mm, the heating temperature was 20–1300 ^° C, and the heating time was 5 s.

 When heating the same workpiece with an inductor having a drop-shaped cross section, the heating time was 8.5-10 s.

 Example 2. For surfacing the inner surface of the sleeve with a diameter of 70 mm, a thickness of 4 mm and a height of 100 mm, a ring inductor was made (see Fig. 5, 6, 7), the inner ring of which is 62 mm, made of a copper tube with a diameter of 7 mm, tube thickness 1 mm. A wire with a diameter of 2.5 mm was wound with a pitch of 2.5 mm and soldered to the tube, and then the surface facing the part was cleaned to the tube.

A VCG 9-6 / 0.44 generator with an operating frequency of 440 kHz was used in the work. The gap between the inductor and the part was 4 mm. The heating temperature was from 20 to 700 ^o C with a further increase to 1200 ^o C. The heating time was 5 s. When surfacing the same sleeve with a ring inductor of a traditional design, the heating was 60 s.

 Using the proposed method of concentration of current on the working surface of the inductor allows you to form ribbed surfaces of the inductor from a wire that is soldered to the inoperative surfaces of the inductor, thereby expanding the technological capabilities of the efficient use of high frequency currents.

Claims (1)

The method of concentration of current on the working surface of the inductor, in which the path of the passage of high-frequency current on non-working surfaces of the inductor is lengthened by forming them in the form of ribbed surfaces in the transverse direction relative to the current flow, characterized in that the ribbed surface is formed from a wire that is soldered onto the non-working surfaces of the inductor , while the parameters of the ribbed surfaces satisfy the condition
a> 0, b> 0, c> 0,
where a is the height of the ribs;
b is the width of the ribs;
c is the distance between the ribs,
taking into account that the roughness of the working surface of the inductor is taken as zero.

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