RU234313U1 - Coated reaper knife - Google Patents

Abstract

The utility model relates to agricultural engineering, in particular to machines for mowing agricultural crops. The reaper knife with a coating is made of 65G steel. The coating is formed by laser-powder surfacing with a size of at least 5-8 mm in width and 5-8 mm in length by simultaneously feeding particles of a nickel alloy and tungsten carbides and/or titanium carbides in a ratio of 10 to 60 wt.%. The desired technical result consists in increasing the wear resistance of the cutting tool and increasing the degree of matrix hardening. 2 fig.

Description

The utility model relates to agricultural engineering, in particular machines for mowing agricultural crops.

The task of ensuring wear resistance and reliability of cutting tools of agricultural machines is relevant. Elimination of equipment stoppages due to tool wear affects both the productivity of harvesting and the economic efficiency of the harvesting campaign.

Among the traditional methods of increasing the wear resistance of cutting tools of agricultural machines, the following are distinguished: heat treatment methods (bulk hardening, high-frequency current hardening), surface modification methods in the form of gas-thermal technologies and coatings, surfacing technologies (manual, semi-automatic, plasma).

Heat treatment methods allow to obtain a hardened tool with a low cost of the process and its mass production. However, resistance to abrasive action is not always satisfactory. At the same time, such knives have low resistance to corrosion wear.

Thermal spraying methods such as flame spraying, plasma spraying, high-speed flame spraying provide a cutting tool with a wide range of performance properties, providing a self-sharpening effect. The resource of knives increases by 2-3 times. However, the use of such knives is possible only in conditions of the absence of strong impact effects, low contamination of soils with rocky inclusions, due to the limited adhesion strength of the coatings to the base, 10-50 MPa depending on the application method.

Surfacing technologies (manual, semi-automatic, plasma) expand the possibilities of using equipment and tools under more difficult operating conditions, abrasive, impact, vibration. The implementation of these methods requires a more careful selection of hardening coating surfacing modes, since it is associated with residual deformations, possible crack formation depending on the surfacing materials used.

Promising methods of hardening the cutting tool of agricultural machines are laser technologies. It is worth noting such methods as laser hardening and laser surfacing. The peculiarity of laser technologies is the locality of their impact with low heat input, high heating and cooling speed of the melt bath, contributing to the formation of an ultrafine structure with improved characteristics, a high degree of automation and controllability of the process. The possibility of using surfacing materials in the form of powder materials allows you to weld layers of various materials or their combinations, including the formation of composites, which significantly expands the effectiveness of laser surfacing technologies for hardening the tool of agricultural machines.

The prior art discloses an iron-based powder for plasma surfacing of agricultural machinery parts in a compressed air environment (Patent RU2637734C1, IPC C23C 4/06, published on 06.12.2017). The iron-based powder for plasma surfacing of agricultural machinery parts in a compressed air environment contains, wt.%: carbon 3.3-4.5, chromium 25-28, silicon 1.0-2.0, manganese 1.0-1.5, nickel 1.5-2.0, tungsten 0.2-0.4, molybdenum 0.08-0.015, sulfur no more than 0.07, phosphorus no more than 0.06, aluminum 0.1-0.15, titanium carbide 0.2-0.25, iron - the rest.

The closest analogue proposed is a coated reaper knife made of steel (Patent RU57747U1, IPC C23C 4/00, published 10/27/2006).

The disadvantage of the specified analogue is the excessive fragility of the applied oxide coating and the possibility of its chipping and peeling off during alternating loading and impacts with the stones of the header knife during operation.

The technical result consists in ensuring wear resistance of the cutting tool – the reaper knife, made of 65G steel with a composite coating with a matrix of nickel alloy and 40 wt.% tungsten carbides volume-distributed in it.

The technical result is achieved by using a workpiece made of 65G steel, on which a wear-resistant coating is formed using the laser-powder surfacing method, measuring 8 mm in width and 8 mm in length, while the wear-resistant coating contains a matrix of nickel alloy with 40 wt.% tungsten carbides volumetrically distributed in it.

The use of a spring steel blank, for example, type 65G, is due to its availability, while this grade of steel provides wear resistance and elasticity of the base material, which is especially important for such products as knives that operate under impact-abrasive conditions.

The use of the laser-powder surfacing method allows for local processing of directly worn areas of the knife teeth. The tooth height of the traditionally produced Rostselmash reaper knives of the S30-0580-61-001 type is 8 mm. Surfacing of areas with dimensions of 8 mm in width and length, i.e. not less than the tooth height, allows for repeated sharpening of the working edge, which is economically feasible.

The separate simultaneous supply of nickel alloy and tungsten carbide particles, implemented in laser powder surfacing, makes it possible to control the operational characteristics of the reaper knives over a wide range.

The wear resistance of the knives increases proportionally with a change in the carbide content from 10 to 60 wt.% The carbide content of up to 10 wt.% does not contribute to the effective strengthening of the reaper knives, increasing the proportion of carbides to more than 60 wt.% is also inappropriate, since the risk of cracking of the deposited layer increases, possible breakage of the knife and, accordingly, a decrease in their durability.

In the utility model, the technical implementation of the method consists of the use of laser-powder surfacing technologies in view of their wide technological capabilities, as well as the formation of a metallurgical bond with the base.

Fig. 1 shows a sketch of a knife with markings of welding zones.

Fig. 2 shows the appearance of the welded header knife.

The essence of the utility model is as follows.

The workpiece is a reaper knife made of spring steel, for example type 65G, obtained by laser cutting from sheet metal of the corresponding steel grade. A wear-resistant composite coating measuring 8 mm in width and 8 mm in length is formed on the working edges of the knife. The coating is formed by laser-powder surfacing. The surfacing materials are simultaneously supplied with nickel alloy matrix particles and tungsten carbides. The coating formed on the working edges is a composite of a hardened nickel alloy matrix and volume-distributed tungsten carbides in an amount of 40 wt.%. The ratio of the initially fed nickel matrix particles and tungsten carbides from 10 to 60 wt.% determines the degree of hardening of the original matrix, the volume distribution of tungsten carbides, and the wear resistance of the cutting tool during forage harvesting operations.

Examples

The knife was made of 65G steel and had a weld zone measuring 3 mm in width and 8 mm in length. During seasonal use, the knife wears out by 2/3 of the layer width. Further use of the knife in the following season led to an unscheduled shutdown of the equipment to replace the knives with new ones, since the hardening zones remaining after the first season were not enough to resharpen the teeth.

The knife, made of 65G steel with a hardening zone of 8×10 mm with a composite coating containing 40 wt.% tungsten carbides, allowed for more than 2 seasons of operation without tool replacement or unscheduled shutdowns.

Claims (1)

The reaper knife is made of 65G steel with a wear-resistant composite coating formed by laser-powder surfacing, characterized by the fact that the said coating contains a matrix of nickel alloy with 40 wt.% of tungsten carbides volume-distributed in it and has a width of 8 mm and a length of 8 mm.