Examples of surfacing repair of the hottest gear p

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Examples of surfacing repair of gear parts

gear transmission parts such as gears, sprockets, ring gears, racks, etc. are commonly used in all kinds of equipment, and the main forms of damage are tooth surface wear and broken teeth. The worn or broken teeth can be repaired by manual arc surfacing, which can not only ensure the normal operation of the equipment in time, but also save a lot of spare parts, which has significant economic benefits. This paper introduces some successful examples of surfacing repair of gear transmission parts for peer reference. 1、 Surfacing repair of broken teeth of gear shaft the heavy herringbone gear shaft of the reducer of a plate mill in a factory is made of 50simnmob steel, with modulus m=30mm, number of teeth z=24, tooth width b = 300mm, and the maximum diameter of the outer circle is φ 914mm, with a total length of 2.75m and a unit weight of 7.722t. The average service life of the gear shaft is 1 ~ 1.5 years, and its damage forms are wear, peeling, broken teeth, etc. At present, only a few domestic manufacturers can produce. The factory used surfacing method to repair a broken tooth with a maximum breaking size of 200mm × 40mm × 45mm scrapped gear shaft, the specific repair process is as follows:

(1) use a hand-held grinding wheel to grind the bottom surface of the broken tooth, and no cracks are allowed. Heat the workpiece before welding, install 24 pieces of far-infrared radiation electric heaters evenly on all tooth top surfaces, and wrap them with asbestos cloth. Heat for about 6h, and control the workpiece temperature at about 300 ℃

(2) selection φ 4mm e (A102) welding rod and φ For 4mm E85, we need to improve the energy density of automotive batteries. 15-g (j857) electrodes should be used for alternate surfacing. The electrodes should be carefully dried before welding

(3) first use e electrode for backing welding with a thickness of about 4mm, then use e8515-g electrode for surfacing welding with a thickness of 16 ~ 20mm, then use e electrode for surfacing welding with a thickness of about 3mm buffer layer, and finally use e8515-g electrode for surfacing welding of the tooth. During the surfacing process, the workpiece should always be in the heating state and placed in a shelter. The interlayer temperature should be maintained at about 300 ℃. For each welding layer, the hand hammer should be used (while hot) to hit each surfacing position for more than 30 times. The whole surfacing process should be carried out continuously and completed at one time. (4) After surfacing, it shall be kept warm for 4H and then slowly cooled

(5) in order to obtain better tooth profile accuracy, the grinding wheel should be used for manual grinding carefully

ultrasonic flaw detection and hardness inspection were carried out on the gear shaft repaired by surfacing, which met the quality requirements. 2、 Surfacing repair of inner gear ring the connection between the traveling part of 50t crawler crane and the upper platform adopts slewing bearing, and the outer diameter of its inner gear ring φ 1400mm, 135mm thick. During gear making, due to the misoperation of the machine tool, the tooth thickness of one of the teeth was milled by half, and surfacing repair was needed. The material of the inner gear ring is 5CrMnMo steel, with poor weldability. The inner gear ring is quenched and tempered, and the corresponding heat treatment is not allowed after the surfacing of the defective gear. Therefore, it is necessary to select the welding rod with the same hardness and adopt the surfacing process to prevent cracks in the heat affected zone. The specific surfacing process is as follows:

(1) carefully remove oil stains, dirt, etc. on the workpiece. Preheat the teeth to be welded and their surroundings to about 300 ℃ with oxyacetylene flame. Surfacing shall be carried out in the workshop, and wind deflectors shall be placed around

(2) selection φ 3.2mm e8015-g (j807) welding rod is overlaid, and the welding rod is baked at 400 ℃ for 1H. When welding, the DC is reversed

(3) place the gear ring vertically on the support so that the tooth surface to be overlaid is in the vertical welding position. Starting from the root of the tooth, multiple layers of upward surfacing are used, and the welding direction of each weld is opposite. After surfacing to the required thickness, rotate the gear ring so that the end face of the gear is in the vertical welding position, surfacing the end face and two sides of the gear until all welding is completed. After each weld is welded, the slag shall be carefully cleaned. During surfacing, the interlayer temperature is maintained at 180 ~ 220 ℃

(4) immediately after surfacing, heat the surfacing area to about 300 ℃ with oxyacetylene flame, then cover it tightly with asbestos cloth and slowly cool it to room temperature

(5) grind both sides of the surfacing tooth with a hand-held grinding wheel, and then process the tooth shape on the slotting machine

magnetic flaw detection and hardness inspection were carried out on the processed surfacing parts, which met the quality requirements of the gear ring

III. surfacing repair of broken teeth of sprocket

when a crane was overhauled, it was found that two teeth of the sprocket in its traveling transmission mechanism were broken from the root, as shown in Figure 1. Because there is no milling cutter and it cannot be remanufactured, it is decided to repair it by surfacing. Fig. 1 Schematic diagram of broken teeth of sprocket the chemical composition of sprocket material is 0.35% C, 1.12% Mn, 0.51% Si, 0.32% Cr, 0.17% Cu. The tooth surface hardness is greater than 50HRC. During surfacing, ordinary low alloy steel electrodes are piled into tooth shape first, and then wear-resistant surfacing electrodes are used for surfacing of tooth surface. The surfacing process is as follows:

(1) before welding, make a template that can measure two teeth according to the tooth profile, so as to facilitate regular inspection of the tooth profile. Place the broken tooth part of the sprocket upward and horizontally, use a steel wire brush to clean the rust on the cylinder surface of the hydraulic cylinder 1 of the meter to be welded and the nearby rust, and clean up the oil stain. Slowly heat the surfacing part with oxyacetylene flame at a preheating temperature of about 200 ℃ to prevent cracks during surfacing. Surfacing shall be carried out indoors in a windless place

(2) selection φ 4mm e6016-d1 (j606) welding rod is used for surfacing welding of teeth, and the welding rod is dried at 400 ℃ for 2h before welding; Select φ 5mm edpcrmo-a (D212) electrode is used for surfacing, and the electrode is dried at 150 ℃ for 1H before welding. 5. Considering the appearance of the printed parts, the AC welding machine should be used for surfacing

(3) firstly, weld the broken tooth surface with e6016-d1 welding rod. Weld the middle part at the end of April this year, and then weld the surrounding parts, so that the welding heat in the middle plays an annealing role on the surface quenching layer of the original teeth, thereby reducing the tendency to produce cracks. Adopt short arc welding, remove the slag after welding one layer, and control the interlayer temperature between 150 ~ 200 ℃. The surface of the surfacing layer shall be as smooth as possible, and the crater shall be filled to prevent the occurrence of crater microcracks. When the teeth are piled up, 2 ~ 3mm thick surfacing amount shall be reserved according to the tooth shape for surfacing the wear-resistant layer

(4) then weld the tooth surface with edpcrmo-a electrode, and complete the continuous surfacing. The tooth surface after welding should be prevented from being uneven, so as to reduce the workload of grinding the tooth shape

(5) immediately after welding, cover the surfacing part with asbestos cloth to cool it slowly

(6) carefully grind and trim the surfacing teeth with a hand-held grinding wheel, and check with a template

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