Induction quenching of shafts and axes

What schemes are used for shafts and axles

For short necks and local areas, quenching is often used when rotating the part in the area of the stationary inductor. For long shafts, axles, rods and rollers, the scanning circuit is more often chosen: the part rotates, and the inductor with a hardening shower runs along the surface. This is already a mechanized hardening complex with speed of movement, delays, the beginning and end of the zone.

UralInduktor forms the concept of the complex and the technical solution for detail and mode. The Chinese factory performs detailed design and manufacture of equipment. The same axis may require either a compact installation for a local neck or a full-fledged scanning machine.

What basic data is needed for selection

For shafts, it is especially important to show all work areas in the drawing, not just the maximum diameter. If the parts have grooves, veneer grooves, carvings, slots, burts and steps, they change the electromagnetic connection and heat dissipation, and therefore the frequency, shape of the inductor and cooling mode.

Steel grade, delivery status and previous heat treatment of the part;

outer diameters by sections, length of each zone, transition radii and the presence of grooves;

what surface should be hardened: neck, track, slot, burt, end or long track along the axis;

the required hardness and effective depth of the layer according to the agreed measurement method;

Permissible beating, crushing and deformation restrictions after hardening;

mode of operation: single parts, batch, serial production, manual loading or mechanization;

available power, liquid cooling and start-up requirements on site.

What determines the metallurgical result

The depth of the hardened layer and the final hardness cannot be deduced only from the power of the generator. They are affected by steel hardness, initial structure, carbon content, part diameter, heating time to austenitization, cooling intensity, and rotation speed. Steel 45 and 40X at the same geometry can require different cycles and give different depth of layer at the same inductor.

Tempering medium also can not be assigned universally. For some parts, a water-polymer solution with an adjustable concentration is suitable, for others - water or another agreed option according to the customer's technology. The width of the zone, the scanning speed and the location of the shower are adjusted taking into account the deformation. Hardness, depth and leash are checked by trial processing.

What series is usually considered

For small local areas, chamfers, thin necks and shallow surface hardening can be considered AVV and AVV. For universal quenching of the shafts of the average diameter, AVZ is more often the starting point. If you need a deeper warm-up before quenching cooling or work with a more massive part, usually assess the AVN. For repair and single operations with the supply of a remote inductor to a fixed part, an LN may be useful, but it does not replace the scanning machine where a repeated long zone is needed.

A simple inductor is usually included. A complex profiled inductor, a set of interchangeable inductors or a quick-shift execution are calculated separately. The final series is confirmed by the detail required depth, real clearance, cooling and stroke; to focus only on the diameter of the shaft is not enough.

Correct approximate calculation for the shaft neck

The following approximate example is only intended for an initial power estimate. Consider a shaft journal 60 mm in diameter and 80 mm long, with a surface layer approximately 4 mm thick to be austenitised before hardening. The annular layer volume is π × 80 × (30² − 26²) mm³, approximately 56 cm³. At a steel density of 7,85 g/cm³, the layer mass is approximately 0,44 kg.

If you take the mean thermal capacity of the steels 0,60 kJ/(kg·C) and heat the layer from 20 to 850 °C, the useful heat will be 0,44 × 0,60 × 830 ~ ≈ 219 kJ, or about 0,061 kWh. With the conditionally accepted overall CDR of the 50 process, a percentage of the network will require approximately 0,12 kWh. If the heating cycle takes about 20 seconds, the average calculated electrical load will be 22 kW. The real process warms up more than the required hot layer, so the calculation reduces the actual energy. The nominal setup, frequency and mode of the soul are specified by the test: the calculation does not in itself show the depth of the layer and the hardness.

How is the inspection and commissioning

Management and documentation are delivered in Russian. After assembly, the Chinese plant checks the equipment with the inductor ordered. Then, in Miass, a second check is performed with full connection without load. The commissioning works are carried out by the customer on his details with the registration of acts.

The warranty is 18 months under the contract. The beginning of the term is fixed by the contract - from the date of shipment or from the signing of the commission act. The price is reported on request after drawing and task analysis. The final depth of quenching, hardness and deformation is confirmed by tests on a real part or an agreed analogue.

What to send for selection

Send a drawing of the shaft or axle, steel grade, required hardness, depth of layer and description of hardened zones. We will prepare a concept, offer a series of AVVS, AVB, AVZ, AVN or LN for the task, we will select an inducer and a verification scheme. Price on request.