How to ensure the longevity of farm equipment?
This question often becomes the cornerstone of modern domestic farmers.
Modern agricultural production is almost impossible without applying on the fields and farms of high-performance agricultural machinery, implements, equipment and tools. The problem of ensuring the required durability of equipment in agricultural production is always important. Given this clarification is required of the main priorities of development of enterprises of agricultural engineering.
Along with such important tasks as using the latest materials technology and high quality components that solve enterprises and design organizations of the branch, work is continuing on the development of modern element base and optimization of structures working bodies for the implementation of the basic production processes of agribusiness.
Directions of improvement of durability of the working bodies of agricultural machinery used in mechanical repair, can be divided into the following groups:
- Substantiation advanced designs;
- The optimization of the geometry of the cutting edges of the blades to ensure that they Samooborona;
- Search and justification of new materials for their manufacture;
- The use of different methods of chemical-thermal and thermal treatments;
- Applying a strengthening and wear-resistant coatings.
Important for the production of highly reliable agricultural equipment has the implementation of the principle of soobscheniya in the manufacture of their working bodies. The principle samooborony is characterized by the selective wear and tear, and ensures the preservation of the pointed configuration of the cutting edge details in the process. For the rational justification of the thickness of the hard and soft layers, it is possible to maintain a pointed profile of the cutting edge at the same level. When this hard layer of the cutting edge is fulfilled more slowly than soft. To extend the life period of parts you can use lower or upper to strengthen the blade.
It is established that one of the positives of parts of plough - share. It is known that the resistance of the blade is 50-70% of the resistance of the body of the plough. That is the state of the blade, thickness of cutting edge and angle of taper dictates the overall resistance of the plow. Often used a chisel ploughshare. They are made of special steel jointers L-53, L-65. The toe and the blade shield harden and set width of 15-20 mm. Blade sharpen the blade to a thickness of 1 mm and a maximum angle of 40 °. The blade, crafted to width of less than 108 mm (tested using a special template), reduced by pulling back to a normal profile with a deviation of a width not exceeding 5 mm, and the length is not more than 10 mm due to the metal back side (store). Pulling is performed not more than four or five times. The drawn surface of the blade should be smooth, without cracks. The deviation of the wall from flatness allowed no more than 2 mm, convexity of the working surface of the blade is up to 4 millimeters.
After pulling the blade sharpen the front side, then heated up to 700 ... 800 ° C and quenched by the width of 20-25 mm in salt 10% water at 40 ° C for 6 from the blade to the hardness 440-650 NV and released at t = 350 ° C With air cooling. To increase resistance against wear of the blade the blade is made self-sharpening, weld it to the back side of the hard alloy "Sormayt No. 1". Before welding in the blade pulled strip with a width of 25-30 mm from the side of the blade and area width 55-65 mm at the toe. The thickness of the deposited layer should be as high as 1.4-2 mm. In repair shops of agricultural enterprises carry out welding acetylene-oxygen flame with a wire diameter of 6 mm with "Sormait No. 1". When the sensing range is 18 to 22 mm (width of blade - less 92-90 mm) shield restore welding an additional strip made from a defective shield or strip, special profiles, steel 45. For this we first cut the worn part of the blade with air plasma or air-gas burner.
The main instrument for continuous and inter-row weeding, for pre-treatment and aeration of the soil using cultivators equipped with sweeps with shank. Only arched feet standard size with 21, including a regular feet, and deposited wear-resistant material. The main criterion of the limit of wear of the clutches is to reduce the width of the wing in the middle part up to 36-38 mm and achieve linear actuation of the sock to 30 mm. maximum thickness of the cutting edge of the blade should be 0.8-1 mm. it Should be noted that linear actuation of the clutches of the aggravation is 2-5 mm. on this Basis, before the agricultural machinery enterprises face the challenge of extending the period of use of hoes without replacement method samooborone.
Paws cultivators are made of steel 65G with cutting edge hardness HRC 44-54. Also carried out experimental studies of hoes, which were made of two-layer sheet with a thickness of 5-6 mm. the Base sheet was made of steel 65G, and the wear-resistant layer of steel Х6Ф1 hardness of HRC 20. Technology staff Wishaw and the Institute of ferrous metallurgy. There are also known methods for increasing the durability of the clutches due to the strengthening of the back of the cementation, cyanidation and hardening. But they have not found their application in production.
Scientists IEW. Paton has established the ability to build steel parts with a thick cutting edge 1-1. 5 mm wear-resistant alloys doped "Sormayt-1", TC-1, HH and pseudopus PS-14-80, PS-14-60. Factories with mass production of the working bodies of tillage equipment "Red star" (Kirovograd) and "Red Akay" (Rostov-on-don) found the application of induction surfacing of parts sorbitol, relita and pseudopus mixtures sarmato.
For strengthening and application of protective coatings is very promising method of electroerosion alloying (EEL). Technological essence EEL involves migration of alloying material on the surface of the alloy with spark discharge in air. Due to the significant range of metals that can be used when EEL, participation of the interelectrode medium in the process of formation of surface layers this method can be used in a wide range to modify mechanical, thermal, electric, thermionic, and other properties of the working surfaces of parts during fabrication and repair.
Plasma spraying of the working bodies of powders of the system aluminum oxide-Nickel provided the improvement of wear resistance of parts two to three times compared with the serial.
Recently, scientists at the National University of life and environmental Sciences to enhance the durability of cutting elements of tillage machines have proposed an effective direction in which control is provided for their wear and tear due to the discrete strengthening of the blades by length or area. Tests have shown that with optimal placement of reinforcing filler points, the durability of the ploughshare of the plow made of steel Л53, increased 4.5-4.8 times.
For induction and gas-powder surfacing of cutting elements using powders based on iron: PG-УС25, PG-С27, PG-FBKH-6-2. For powder and plasma-powder surfacing of cutting elements of working bodies of machines interesting powders based on Nickel and cobalt. CIS can offer the following mixture: US-25, Stalin, sormayt; batch HH, KB. Foreign firms produce samplesonline powders Cabot (USA), "ITR" (Austria).
To ensure adequate accuracy of the surface during manufacture and repair of parts capable of cold recovery methods. In modern manufacturing and repair of most automotive products agricultural equipment to ensure proper operational properties using galvanic dry topping and chrome plating. These methods of influence on the surface layer will avoid the negative phenomena arising from the use of hot methods. Such coatings put forward a number of requirements. They must be: good adhesion, the presence or absence of pores in the coating (depending on operating conditions), low surface roughness (assuming the possibility of achieving significant coating thickness).
For repair production, in particular agricultural machinery, the main point is the cancellation of machining a workpiece up to and after her recovery chrome.
Some of these methods are already used successfully on the advanced repair shops for machining parts, for example, finishing of parts made by cold plastic deformation. The essence of this method lies in the fact that under the influence of the deforming element (ball, roller) by mutual relative movement of the tool and the details of the inequality of the treated surface plastically deformed. Such processing is high performance and gives you the opportunity to obtain a surface with roughness grades 9-12 in conjunction with the strengthening of the surface layer. This method is applicable to all metals which are deformed in a cold condition: unhardened steel, non-ferrous metals and cast iron. For processing by plastic deformation of outer cylindrical surfaces and holes used tools and the deformable elements of different designs. To ensure high precision machining of holes, used hard ball and roller rozetochki. Details of the processing by plastic deformation reaches 40-70% relative strengthening, microhardness of the surface increases by 25-54% when the depth of deformation 0,08-0,18 mm, the fatigue strength increased by an average of 15 percent.
The importance of lengthening the service life of body parts from cast iron, which specifies the configuration of the machine and the relative placement of other parts. One of the defects of case details that are harder to fix, cracked. There is a whole range of different ways to eliminate cracks, among which, in our opinion, the practical application in modern conditions of economy of Ukraine has gas welding.
Gas welding of cast iron is carried out with neutral flame or with a small excess of acetylene welding torch choose to provide the output of the flame from the calculation of the flow of 100-120 l / h of acetylene per 1 mm thickness of metal. Depending on the amount of welding required, you can use the burner No. 3, 4 or 5. Filler materials may be iron rods with a diameter of 6-8 m. the Melting of cast iron strongly absorbs oxygen from the air and is covered with the oxidation film. Since the melting point of cast iron 1200 ° C, i.e. below the melting point of its oxide (1400 ° C) when welding fluxes should be applied, namely: 1) borax (Na2B4O7) 2) a mixture of 50% borax, and 47% of sodium bicarbonate (NaHC03) and 3% silicon oxide (Si02), 3) a mixture of 56% borax, 22% sodium carbonate (Na2C03) and 22% potassium carbonate (К2СО3). Flux contribute to the welding method of dipping the heated end of filler rod.
When welding with heating of the housing parts made of gray cast iron using special electrodes, such as TMC-1. To cover the electrodes, a mixture composed of chalk (25%), feldspar (25%), graphite (41%), ferromanganese (9%), liquid glass (30-35%). The coating thickness over the diameter of the electrodes 6 to 10 mm is taken in the range of 0.5-1.1 mm. arc Length should equal the diameter of the electrode. For electrode diameter 6 mm recommended current of 250 A, 8 mm, and 10 And 350 mm to 450 A. welding of cast iron without pre-heating is carried out with electrodes of mild steel, copper electrodes or electrodes made of Monel metal (an alloy of copper and Nickel).
Low carbon electrodes are rods made of steel 08KP 10 or with coating (electrodes type E-34). Weld electrodes with a diameter of 3-4 mm for the current 30-40 A / mm diameter metal rod electrode). Weld sections with breaks, giving the parts an opportunity to cool to 50 ... 60 ° C. copper electrodes are the electrodes of SPD-1. They consist of a copper core and coating: marble - 27%, ferrotitanium - 6, ferromanganese - 2,5, ferrosilicon - 5%, fluorspar - 7,5, quartz sand - 4.5 and iron powder - 50%, containing at least 96% of the metal. Soluble glass is taken in an amount of 30% by total weight of the components. The thickness of the coating on the side for diameter of the electrodes 3 to 5 mm take 0,9-1,6 mm, the current is 90-200 A. welding electrodes SPD-1 is performed only with direct current at reverse polarity.
Summarizing the above, we can say that the reliability of agricultural machinery depends on the level of study and the perfection of each of the presented methods and directions. Improvement of agricultural machinery, the development of technologies to restore their functionality contributes to the further development, and complexity of the systems and methods of increasing their reliability. Increase of life is inseparably connected with the problem of durability of machines, units and especially of the working bodies, which determine the quality of the process. The successful solution of these problems depends on the knowledge of regularities of friction and wear, which are determined not only by the material properties of parts subjected to friction, but with the conditions of their use.