The method of restoring worn parts

B23P6/04 - Repairing fractures or cracked metal parts or products, e.g. castings

(57) Abstract:

The invention relates to the repair, in particular to a method of restoring worn parts, and gives the ability to control the tensile stresses, resulting in additional repair parts, when fixing them by welding to restore and improve the ductility of welds. The invention consists in that an additional process details and pre-set fixed on unheated restored details. Then the recovered items in the collection process is heated to a predetermined temperature, and before welding the joints of these parts and welding them to the restored details make the cooling of the parts by a specified amount without cooling the recovered parts. Welded joints and welding technology details make using omigawsh rollers. Application of the method is promising when restoring journals of crankshafts of automotive engines, compressors and vacuum pumps. 2 C.p. f-crystals, 2 Il.

The method relates to a mechanical Assembly production, to a method of restoring worn parts machines with worn surfaces set ASS="ptx2">

In particular, the invention relates to the field of recovery of shaft journals, such as crankshafts, automotive piston engines, compressors, vacuum pumps, etc. when worn or damaged cervical restore by installing and fixing them hardened steel repair semirings.

The invention can be used to restore the journals of crankshafts in repair shops and repair shops.

Known methods analogous to restore the journals of crankshafts. The method is similar as described in the book, I. E. Ullman "Repair tractors, M-Sverdlovsk (in Russian) the motor cycle", 1952, pages 246-247, Fig.184.

By the method similar worn cervical crankshafts process to given dimensions under additional repair parts, made in the form of two half-rings of different thickness. Repair half rings are made of medium-carbon steels of different brands and they hardened. In joints for welding is produced chamfer. In the recovery process of repair half rings mounted on unheated shakes shafts, Orient their position, to draw necks and then the weld repair semirings gas flame heated to a temperature of 150-200^{The disadvantages of the method-analogue consist in the fact; that the repair parts are not connected with the body parts by welding or any other method, and welding joints perform without the use of ujigawa rollers.
During operation there is a deterioration of micro - and macroprocesses contacting surfaces and the weakening of the landing repair half-rings on the neck. So they offset necks, the overlap of the oil channels in the neck and prevent admission of lubricant to the friction zone. There is a meeting of repair semirings in the bearings and the resulting failures.
Heating repair semirings before welding though and increases the plasticity of the material in the seams, but leads to increased tensile stresses in semirings and to increase the likelihood of cracking that can be explained as follows.
Repair semiring set on cold, cervical rolls, presses them to the necks using prismatic adjusting elements of the devices. After pressing the welding zone, i.e., repair of a half-ring located on the cold shakes, heated by a gas flame. As a result of external heating temperature maintenance semirings becomes more temperature teaki. Gaps in the joints repair semirings additionally reduced. In this condition, the joints repair semicircles connected by welding to form a continuous repair the ring.
In the process of cooling and alignment of the temperature fields in the repair ring is shrinkage of the material, and the body of the neck extends, as the heat from the repair semirings goes into the neck. The result is an abrupt increase of the voltage in the repair ring, there is additional tension and increase the probability of failure in the weakest place, usually in the area of welding seams.
Therefore, in the method-analogue external heating of the weld zone of repair semirings does not reduce the formation of cracks, and to their increase.
To reduce the formation of cracks in the weld zones and the weakening of the tensile stresses in repair semirings you want to create a higher temperature in the body of the cervix and lower temperature in the repair of the ring. Then weld joints. In this case, the alignment process body temperature and cervical repair semirings will be heating and increasing the length of the repair semiring, cooling and reduction of the sizes of necks. This will result in the ass is">
In our invention the disadvantage of this method is similar eliminated.
Known way to restore parts, which by its technical essence is the closest to our technical solution and is its prototype.
The prototype method is described in the article Poucelina centuries Alexandrov Century. N. "Increase resource worn crankshafts", journal of Technology in agriculture", No. 3, 1985, page at 52.53, but also in their article "the Effect of a new method", journal of Automobile transport of Kazakhstan" No. 12, 1986, page 9.
The method of the prototype restore cast iron crankshafts automobile engines ZMZ-53 by mounting on the neck additional repair parts, made in the form of hardened steel half-rings.
The method includes processing necks under repair semiring, the installation of hardened steel half-rings on the neck of their orientation, and to preload necks, electric arc welding of joints between themselves and simultaneously welded them to the necks.
The disadvantages of the prototype method consist in the fact that in the process of welding joints repair semirings do not use any technological methods, precluding the formation of cracks in welds and heat affected zones.
is rcoi, allowing to increase the ductility of welds and to reduce the tensile stresses in the repair parts.
Welded joints produced without the use of ujigawa welding rollers. The welding process of the second and subsequent joints are without additional cooling repair parts to a temperature equal to or lower than the temperature of the recovered parts in the process of welding joints.
Therefore, the aim of the present invention is to improve the reliability of recovered parts by reducing the likelihood of cracks in the weld zones.
This objective is achieved in that after the installation of repair parts for unheated recreated, their mutual orientation and Ref, make a preliminary fastening of repair parts for restored at one point, before welding joints apply common heating repair and restore the parts to a predetermined temperature, which is chosen by more ambient temperature and below the tempering temperature of the hardened parts, after a joint heating repair and restore parts before welding the second and subsequent joints, produce cooling repair parts to given the ways gland accessories, and welded joints produced using omigawsh rollers, in the process of applying the first welding platen simultaneously melt the ends of the repair parts in the joints and the surface is recreated, and the gaps in the joints filled with molten metal partially, when applied omigawsh rollers gaps in the joints filled with molten metal completely and create the set too much.
The invention is explained in the following drawings.
In Fig. 1 for example, the recovery shaft journals shows a diagram of a prior attachment of composite repair parts recovered.
In Fig.2 (a, b, C) shows the recommended schemes for welding joints with drawing omigawsh rollers.
On the drawings and in the text the following notation: 1 - restore item, made in the form of shaft journal; 2 and 3 constituent parts repair parts made in the form of repair semirings; 4 seam temporary mounting parts repair parts to restore, for example, obtained by welding; 5 main welding seam connecting the repair parts between the joints and connecting them to recover; 6, 7 and 8 origaudio cushions.
Orient the position of repair parts for restored and draw them to the surface restored. By welding or other known method produces tack and consolidation of repair parts in a given position at one point.
Remove the gland accessories. Heat recoverable detail in conjunction with repair to a predetermined temperature, for example, in an electric heating furnace. The heating temperature is chosen and set at approximately this, which does not preclude treatment with the heated detail work gloves. In General, the heating temperature must be greater than 40^oC and less than the tempering temperature of the hardened repair parts.
Hot item set on the stand. Short of repair parts for restored with the help of the gland elements of devices, providing intense heat from the repair parts.
Reduce the temperature of the repair parts in comparison with the Central part of the body recreated by a specified amount. Reducing the temperature from the 5^oC to 50^oC. Find the temperature difference of repair parts and restored before welding empirically.
Produce welded joints composite repair parts and welded them to the restored using omigawsh rollers in one of the schemes shown in Fig.2.
Rational scheme of welding joints using omigawsh rollers is chosen empirically. The length omigawsh rollers choose within 30.50 mm Between the application of separate rollers for flattening the temperature produces endurance, which is chosen empirically in the range of 0.3 to 2.5 minutes.
According to the invention for welding joints of repair parts in the process of applying the first main roller choose welding mode and the movement of the electrode, which ensure complete melting of the end surfaces of repair parts and the surface of the recovered components in a predetermined depth. Moreover, the gap in the joints filled with molten metal does not fully value the filling of the gap is chosen empirically. In most cases, you can focus on filling the gap with molten metal by an amount close to 50% interest.
According to the invention, the clearances in the joints d is the N 4713295/27(90191) from July 3, 1989, for VNIIKP took a positive decision. Therefore, the order of selection of rational open joints in this application not stated.
Produce slow cooling rebuilt parts, for example, in hot sand or in a thermos. After cooling the details it is directed to the processing of restored surfaces in specified dimensions.
Example. You want offer a way to restore cervical crankshafts automobile engines ZMZ-53.
Crankshafts are made of high-strength modified iron.
Repair of the ring is made of medium carbon steel grade 45, hardened and passed a vacation at a temperature 350.400^oC and have a hardness in the range of HRC_e-42.47. The thickness of the repair semirings 2.5 mm
The nominal diameters of the connecting rod journals of crankshafts 60 mm, 70 indigenous mm
Before installing the repair half-rings, crank pin handle up to a diameter of 56 mm, and indigenous to the diameter of 66 mm found that the gaps in the joints should be 5.6 mm
After sanding necks to given dimensions, set the crankshafts in stand-tilter, designed to build necks with repair palakollu at the neck with holes in repair semirings and align the gaps in the joints. The joints should be located in areas of least wear (see and.with.USSR N 1207666). Draw repair semiring to necks and produce their tack in one of the joints for welding necks.
Installation and tack repair semirings can be executed in two variants of the sequence of operations, namely, to heat the crankshaft and after heating. The first option is more acceptable because it is easier to assemble and eliminates the possibility of burns during installation, repair rings and their prior attachment to the necks. Installation and repair of semirings heated, the shaft is accompanied by increasing complexity of the Assembly process and is dangerous to the worker.
Crankshaft Assembly with repair semirings load in an electric heating furnace and heated to a temperature 100.140^oC. Then remove from the oven and set in the stand-tilter for welding joints. Push the ring to the necks using the cold heat of the gland elements, for example, we have developed adaptations (see and.with.USSR N 1682105).
Welding joints begin after soaking repair semirings in pojetom condition approximately 0,5 min.
Produce welding Steig.2. The less preheating temperature crankshafts and the higher the carbon content in the material of the shaft, the greater the number omigawsh rollers cause.
Welding joints perform welding machine in an environment of carbon dioxide welding wire SV-08G2S diameter of 1.0.1.2 mm when welding current 120. 130A. Between applying omigawsh rollers produce an extract 20.30 seconds. When applying the first seam joints selects the mode of movement of the electrode wire and move it into the gap, providing a complete fusion of the joints repair semirings and the surface of the neck of the shaft to a depth of 1.0.1.5 mm At the same time provide a gap in the junction of the molten metal by approximately half.
After welding joints details cooled in pre-heated to a temperature 50.70^oC sand or in a thermos.
Then crankshafts are sent to the welding quality control and processing of journals in specified dimensions.
Developed a method of recovering components has the following techno-economic advantages.
1. The proposed method of repair parts allows you to change in a wide range of the tensile stresses resulting from usagc the tion zone. To improve the quality and reliability of remanufactured parts.
2. Welding joints repair parts and welding them to recover, with the use of heaters in the collection and omigawsh rollers eliminates the possibility of formation in the weld zone hardening structures, decreasing the ductility of the material and increases the fragility, with relatively small gaps in the joints.
3. The installation of repair parts for unheated restored details and preview their attachment eliminates the need for Assembly is heated recoverable parts repair and the possibility of burns in the Assembly process. The result is increased security works and simplifies the recovery process.4. The proposed method makes it possible to create conditions when welding joints and welding of repair parts for the recovered during cooling and the temperatures is heated additional repair parts due to the heat recoverable and increase their size while cooling and reducing the size of recoverable items. When cooling occurs, the strain relief of repair parts to the recovering of the Menem before welding of parts and simplifies the process.
1. The method of restoring worn parts, including processing of worn surfaces of recoverable parts, install them and fixation of technological components, welding and subsequent processing, wherein after installation of technological components and their fixation perform first joint heating, and then before welding produce cooling technological details to a predetermined temperature.
2. The method according to p. 1, characterized in that the technological details before committing to draw recovered using the jigs, the gland elements which are cooled to a predetermined temperature.3. The method according to PP.1 and 2, characterized in that the welding is carried out in two or more passes with time or without time between passes.}

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