SU1740456A1 - Process for heat treatment of coarse-pitch involute gears - Google Patents

Abstract

Use: The invention relates to metallurgy and can be used for induction heat treatment of coarse-grained gear wheels of an involute profile, mainly operating in an abrasive environment. SUBSTANCE: coarse-grained gears are subjected to induction heating for quenching up to 880-900 ° C, sprayer cooling is carried out with water, then induction heating is performed for tempering using a patch indicator up to 530-550 ° C. cooling lead to air. 3 il. Yo

Description

The invention relates to the field of metallurgy and can be used for induction heat treatment of coarse-grained gears of an involute profile operating in an abrasive environment.

A known method of heat treatment of gears, including volumetric heating for quenching, cooling during quenching and high-temperature tempering-improvement, providing uniform hardness HB 300 on the entire working surface of the teeth and in the cavity.

The disadvantage of this method is the reduced wear resistance of the working surface of the teeth, which drastically reduces the durability of gear wheels operating under abrasive conditions.

There is also known a method of heat treatment of gears, which provides for additional surface hardening of gears and includes induction heating under the sealing of the side surfaces of adjacent teeth and the hollow between them (in the hollow), quenching cooling and tempering, ensuring uniform high hardness CJ.HRC 45) surface to be treated. This process is carried out in furnaces or furnaces at a corresponding constant temperature.

The disadvantage of the method adopted for the prototype is reduced durability due to the increased vibrations of a gear drive operating in an abrasive environment. Very low flexibility of the working surface of the teeth of the plate;

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This deformation leads to a significant shaping of their involute profile, chipping of the working surface in the circumpolar zone, which causes increased vibration of gears operating in an abrasive environment.

The task is to create a method of heat treatment (surface hardening) of gears, which allows to obtain a variable hardness along the height of the teeth, decreasing in the direction of the initial circle.

Such a nature of the change in hardness allows the involuntary tooth profile to remain unchanged during the operation of involute gears under conditions of abrasive wear due to the facilitation of plastic deformation in the near-pole zone during transfer-in running-in and wear by rubbing up high hardness areas, which in turn , leads to a decrease in the concentration of specific contact and dynamic loads and, consequently, the vibration of gears, as well as to increase their reliability and durability.

The purpose of the invention is to increase the durability of gears by providing variable hardness over the height of the teeth of gears.

The goal is achieved by the fact that in the method of heat treatment of coarse-grained gears, including induction heating for quenching the working surfaces of two adjacent teeth and the hollow between them, quenching and tempering are performed by tempering by induction by periodically applying power to the hardened surface of the teeth.

Figure 1 is a schematic of the device for carrying out the method, the design of the inductor for uneven heating of the gear teeth during tempering; figure 2 - the same option; FIG. 3 shows the nature of the change in hardness in tooth height.

A device for simultaneous induction heating of two working surfaces of a single tooth (Fig. 1) is an inductor applied to a tooth, made of a water-cooled copper tube 1 of oval cross section, oriented along the profile of tooth 2 in the area of the initial circle with a corresponding gap. The width of the active wire is 0.4-0.6 t (t is the gear module, mm).

In order to avoid overheating of the end sections of the tooth, an increase in the gap between the inductor and the part at the end is provided.

gears and the radius of curvature of the loop 3 between the forward and reverse branches of the inductor.

With such a device, the near-pole area of the working surface of the tooth, located directly under the inductor, is heated mainly by the active current by a single or multiple power supply (switching on the heating) with subsequent pauses for heating due to heat conduction, and the zone at the top and bottom of the tooth only by heat conduction that provides uneven heating during tempering over the height of the tooth.

The device for continuous-sequential induction heating at the trough (Fig. 2) is used with a significant length of the gear tooth and is a two-section (multi-section) inductor with a series connection of sections (I and II), which provide in the process of movement along the trough (along the arrow) periodic (in this case twice) power supply to the hardened surface of the depression with subsequent pauses, during which the neighboring zones are heated due to heat transfer from the layers heated by the active current.

The inductor head, placed in the hollow, consists of two copper plates 1, forming together with a water-cooled profiled copper tube 2 welded to them, an active inductor wire, and a magnetic conductor 3, assembled from electrical steel plates and placed between the copper plates and the tube passing along the bottom hollows.

In accordance with the goal of providing uneven heating over the height of the teeth, the induction head should differentiate the intensity of heating of the near-pole zone, the top and bottom of the teeth with the predominant power supply to the near-pole zone, which is achieved by the F-shape of the inductor's main working element.

The method of heat treatment of coarse module involute gears is carried out in this sequence. Uniform induction heating for quenching at the trough; spray cooling in the quenching process; water, air, air mixture, etc .; can be used as a quenching medium depending on the steel grade; induction heating uneven in tooth height during tempering by periodically, including once, supplying power to the working surface followed by a pause for heating the adjacent zones due to thermal conductivity .m

In this case, the heating method (simultaneous in tooth or continuously sequential in the hollow), the heating parameters and the type of device for its implementation and the need for intensifying the variable temperature along the gear teeth, are determined by the value of the specified hardness difference and the geometric dimensions of the tooth.

The energy and thermal parameters of heating are set in each particular case experimentally. Thus, when heating at a lower specific power, a decrease in the heating rate leads to an increase in the role of the thermal conductivity factor, an increase in the depth of the heated layer and a decrease in temperature difference in the height of the tooth and may require concomitant pressing of the top and bottom of the teeth with compressed air

The invention is as follows.

Samples of sin teeth m 20 mm (and two troughs) 180 mm long made of 40X steel are subjected to induction heating for quenching on the trough: current frequency - 8000 Hz; specific power P0 1.3 kW / cm2 - the speed of movement of the inductor is 3–5 mm / s:

opporatura natura ngREVA hardened 880- uii c; cooling in quenching process — cooling medium — water; hardness of the hardened surface HRC56.0 depth of the hardened layer in the near-pole zone

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4.0 4.5 mm, in the depression 2.5 mm; induction tempering by (single-roll) power supply to the hardened surface of the teeth; (a pot of initial circumference of width u, bm - 12 mm); current frequency 1000 Hz specific power, 4 kW / cm2; heating time 10 s; surface heating temperature at the tip of the tooth 360-390 ° С, in the initial zone

yuyo sG00 ™ at the base 3Uba 360 Results obtained; HRC hardness At the top 45-50; in the zone of the initial circle 30-35; at the base of the tooth 45-50.

The nature of the change in hardness in tooth height is shown in FIG.

The use of the method of heat treatment of coarse-grained involute gears can significantly increase the durability of a gear drive operating in an abrasive environment, for example, the gearbox of a ball mill W-50A for grinding coal, 2.5 times.

Claims (1)

Claims The method of heat treatment of coarse-grained involute gears includes induction heating for quenching the working surfaces of two adjacent teeth and the depression between them, quenching and tempering, characterized in that in order to increase the durability of gears by providing varying hardness in tooth height, the heating for tempering has induction by periodically applying power to the hardened surface of the teeth. Aa 15 20 five 0 Odl BudG r SHShShSh / 2 ZO No. 5O T & rzgb, tfЈC Phage.Z