RU2120363C1 - Induction surfacing method - Google Patents

Abstract

FIELD: mechanical engineering. SUBSTANCE: prior to surfacing, grooves are made on surfaces to be strengthened to form buffer zones. Grooves are cut in direction perpendicular to direction of movement of friction pair. Pitch and profile are set to meet requirements to needed buffer layer. Depth of grooves is set according to relationship: h ≥ 2Δ where h is depth of groove, mm; Δ is depth of penetration of current at induction heating, mm. Grooves are made rectangular, triangular or oval with increase in contact surface between fusion layer and base metal depending on conditions of operation of buffer zone. EFFECT: increased wear resistance of parts and units operating at high impact loads, enhanced quality of surfacing owing to increased strength of adhesion of applied layer and base metal. 4 cl, 5 dwg

Description

 The present invention relates to mechanical engineering and can be used to increase the wear resistance of various parts and assemblies operating under shock loads.

 There is a method of induction surfacing (see Russian patent N 2058866, class B 23 K 13/01), in which a mixture in the form of particles with sharp edges is applied to the surfaced part to create an edge effect.

 The disadvantage of this method is that with the help of the edge effect that occurs in particles with sharp edges, the entire charge volume is quickly heated to melt, but the problem of combining the base metal with the deposited metal with the specified physicomechanical requirements of the deposited layer is not solved, which leads to a decrease deposition quality and possible shifts of the base metal relative to the deposited.

 For the prototype, the method of induction surfacing was selected (see application N 95110096/08, positive decision of 07/07/96), which consists in the fact that the surfaced surface is reinforced with rods that are buried half their thickness in grooves, the latter being pre-marked on the surface parts in a certain order, depending on its configuration, on sectors or areas equal in area and are applied mechanically by a depth equal to half its width, while a wire of different cross-section or metallic is used as a rod ical crumb, which groove is filled.

 However, reinforcement, which allows reducing stress in the deposited metal on large friction surfaces of large-sized products, does not remove the issue of stress concentration in the transition zone, (i.e., the charge is the base metal), which arises as a result of different thermal expansion coefficients of the alloy and the base metal. This circumstance leads to high stresses in the fusion zone of the deposited and base metal and under conditions of operation at high dynamic loads adversely affects the adhesion strength and, accordingly, the quality of surfacing.

 The purpose of the invention is to improve the quality of surfacing by increasing the adhesion strength of the deposited layer with the base metal and increase the contact strength of bimetal.

The essence of the proposed method is illustrated by drawings, where in Fig.1 shows a surfaced surface with a buffer zone, made in various ways:
a) a fragment of a buffer zone made with rectangular grooves;
b) - a variant of triangular grooves;
c) - a variant of the sinusoidal grooves;
g) - a variant of the grooves in the form of semicircles; figure 2 - diagram and schedule of the buffer zone under static load; figure 3 - diagram and schedule of the buffer zone under mixed loading; in FIG. 4 - diagram and schedule of the buffer zone with high impact strength; figure 5 - shank of the automatic coupler.

 The proposed method is implemented as follows.

 On the hardened surface of the product before surfacing, a relief is made that can be made in the form of rectangular grooves (see Fig. 1, a), triangular (see Fig. 1, b), sinusoidal or semicircles (see Fig. 1, c, d).

мм,
где
Δ - глубина проникновения тока (т.е. это толщина слоя, в котором выделяется основное количество, мм тепла при принудительном нагреве);
f - частота переменного тока в индукторе, кГц.Grooves are cut using a metal-cutting tool, for example, a milling cutter, a cutter or a cutting stone in the direction perpendicular to the movement of the friction pair. The groove depth h is determined from the condition that it should be twice as large as the penetration depth Δ, current during induction heating, i.e. h ≥ 2Δ. In this case, the current penetration depth, determined by the empirical formula

mm
Where
Δ is the current penetration depth (i.e., this is the thickness of the layer in which the main amount is released, mm of heat during forced heating);
f is the frequency of the alternating current in the inductor, kHz.

 In addition, the pitch and groove profile are set based on the technical requirements for the adhesion zone of the deposited layer with the main, the so-called buffer zone. This zone is created both over the width of the entire surfacing, and in certain areas where it is necessary to artificially increase the contact surface between the base metal and the weld to increase the mechanical properties of high viscosity.

 Buffer zones can alternate with different gaps depending on the operating conditions of the parts and assemblies (see figure 1).

 If it is necessary to operate the buffer zone in the mode of static loads and in the absence of shocks, the grooves are cut rectangular (see Fig. 1, a), and the depth h is determined depending on Δ the current penetration depth, and the step L = 2 l, where L is the step , l is the distance between the profile grooves.

 From the graph (see figure 2) the operation of the rectangular relief shows that when the buffer zone under static loads, the wear resistance is constant, and the place of stress concentration does not affect the toughness of the deposited layer.

Из графика (см.фиг.3) видно, что износостойкость переменна и связана с величиной износа буферной зоны прямолинейной зависимостью. В местах концентрации напряжений переходы от наплавленного слоя к основному материалу меньше проявляются по углам их перехода.In the case of the buffer zone under mixed loads, namely statistical and shock at the same time, the grooves are triangular (see Fig. 1, b), and the depth is determined depending on Δ the current penetration depth, and the step

It can be seen from the graph (see Fig. 3) that the wear resistance is variable and is related to the wear of the buffer zone by a linear relationship. In places of stress concentration, transitions from the deposited layer to the base material are less pronounced at the transition angles.

(для синусоидальной канавки).When the buffer zone is in shock mode with increased impact strength, the grooves are oval, for example sinusoidal or in the form of semicircles (see Fig. 1 c, d), while the depth is also determined depending on the current penetration depth, and the pitch

(for the sinusoidal groove).

(для полуокружности).

(for a semicircle).

 The graph of FIG. 4 reflects that with an oval groove, the buffer zone most favorably operates in the shock mode, since voltage concentrators in the transition zones of the deposited and base metal are in a sinusoidal plane.

 Wear resistance depending on wear also changes curvilinearly.

 After the deposition surface is embossed, a layer of the charge is applied onto it with a thickness necessary for filling the grooves and subsequent shrinkage during melting.

 Then, the hardened surface is introduced under the inductor and deposited by the induction-metallurgical method. Further, the part or product cools in air and in the process of cooling, slag self-separation occurs.

 Example.

Initial data for surfacing the shock of the shank of the automatic coupler:
the thickness of the applied layer of the mixture 5 ⁺¹ mm;
the intensity of heating 70 - 110 ^o C / s;
the speed of movement of the part under the inductor is 1.5-2.5 mm / s.

 inductor AC frequency 440 kHz. The gap between the base metal and the floating coil of the inductor is 2-2.5 mm. The gap between the heating coil and the base metal is 6-7.5 mm.

 Technological operations when surfacing the end surface of the shank of an automatic coupler.

Mark on the weld surface of the groove in the direction perpendicular to the curve of the nape. Then cut oval grooves with a depth of h = 2 mm, l = 4 mm, in increments of L = 1.57 l; L = 1.57x4 = 6.28 mm using a cutter (see Fig. 5). After that, the automatic coupling body is mounted on the manipulator, it is fixed and the end surface is heated to a temperature of 500 - 650 ^o C. Then, a layer of the charge is applied to the end surface of the shank.

Alloy PG-US435-82% and boron-containing flux NP-2 - 18% with a thickness of 5 ⁺¹ mm. Measure the thickness of the layer on the protrusions.

 The automatic coupling body is moved under the inductor in the longitudinal direction, producing a sequential melting of the charge on the entire hardened surface. After that, the body is removed from the manipulator and the hardened surface is cooled, during which the slag crust is separated from the surface of the deposited alloy. When local protrusions are detected, the surface to be hardened is cleaned.

Surfacing of the thrust plate mating with the end surface of the shank is carried out with a continuous layer of PG USCH-35 alloy 1.5 ^+0.5 mm thick using a special tilter ensuring the horizontal position of the liquid bath.

 Using the proposed method of surfacing allows to increase the contact surface between the base metal and the charge by providing an embossed relief surface, ensuring their adhesion strength, and the relief in the form of grooves of various profiles allows you to program the properties of the buffer zone depending on its working conditions, which improves the quality of surfacing .

 In addition, the relief of the deposited surface allows you to increase the intensity of heating of the base metal, because On the edges of the grooves, countercurrent heat fluxes are formed under the action of the edge effect, creating a stable thickness of the buffer layer due to the filling of the grooves with the deposited alloy. This circumstance not only increases the productivity of surfacing, and most importantly eliminates the destruction of the transition zone during the operation of nodes and parts in shear with high impact loads.

Claims (4)

1. The method of induction surfacing, including cutting mechanically on the deposited surface of the grooves, followed by applying a surfacing charge, processing it with an inductor before melting and finishing, characterized in that before deposition on certain areas of the hardened surface create buffer zones by applying a relief in the form grooves that are cut in the direction perpendicular to the movement of the friction pair, and the pitch and profile of the latter are set based on the programmed technical requirements for the buffer the black layer, while the depth h of the grooves is set in accordance with the dependence
h≥2Δ,
Where
Δ is the depth of current penetration during induction heating.  2. The method according to p. 1, characterized in that under static loading of the buffer zone, the groove profile is rectangular.  3. The method according to p. 1, characterized in that when the buffer zone is in mixed mode, namely static and shock, the groove profile is triangular.  4. The method according to p. 1, characterized in that during shock loads the profile of the grooves is oval.

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