Welding repair of coal mining excavator spoon an other details in Palaj-Kastriot.

Ramaj, Vehbi ; Ramaj, Valbone ; Koleci, Abdyl 等

1. INTRODUCTION

With the purpose of maintenance and functionality of the rotor of coal mines at Bardh and Mirash work for repair and improvement of various parts for the mining of coal are needed. The repair of equipment such as the rotor of excavator and other different parts can be carried out in the factory in Palaj (FPX) and thus meet the needs for a proper functionality energy chain between mines and power plants. In this paper will provide the repair with the welding coal mining excavator spoon RS 470 (RO-7) for mines surface of Mirash and Bardhi and some other details, and control of these details. During our engagement with the workers of the central machinery of the factory, we found out that for years they have not been able to repair the coal mining excavator, but recently made the repairs with the coal mining excavator and welding parts for coal for wasteland (Bytyqi & Osmani, 1996).

Advantage of the method of repair welding of coal mining excavator is the opportunity to repair concave different in a short time.

2. CAUSES DAMAGE OF COAL MINING EXCAVATOR SPOON IN PALAJ

Causes of damage of coal mining excavator spoon, repaired the wheels with welding equipment in the factory, are different from most, but we will be in this way:

* Speed of large rotation.

* Deepening spoon more than that should in-depth material (step spoon is greater than that required).

* Inadequate with centre the teeth of spoon

* Angles of the teeth

* Non-dental distance level.

* Material is inadequate construction to spoon.

* Material teeth are not good.

* Tightening not well for teeth.

* Welding not well for parts of different spoon.

* Relationship between spoon and wheels working.

During the work, can also be the main cause of deviation from spoon working wheels, plates heats while working with construction wheels and this is very dangerous for damaging spoon during excavation of wheels working for coal or spoon wasteland.

Basic material coal mining excavator spoon is St 37-3.

Types of spoon to excavator to wheels change by type of the construction and dedication, (Ramaj, 2007).

3. BASIC MATERIAL

Spoon basic material is steel and is stable against sticking. The tooth is placed where called knife and materials should be stable. Teeth are melted by Manganese and vary much depend on the dedication and we have different types of teeth such as teeth: long, short, frontal, side, narrowing, left, right etc. In case of damage to teeth, change becomes their prepared to establish new ones as well, but usually come to lament the parts construction and therefore even repairing them. The basic material of spoon for coal is steel is St 37-3 with chemical composition and mechanical properties that are given tables below (Ramaj et al., 2007).

4. FILLER MATERIAL

Analyzing the mentioned factors it is concluded that suitable technique for welding is GMAW-MAG method, while the wire- electrode is used VAC 60 with the diameter 1.2 mm. Selected electrode will have the following chemical composition and mechanical properties (Ramaj et al., 2007).

5. THE DETAILED PREPARATION FOR REPAIR WITH WELDING

Preparation of details for the repair welding process is a very important quality of a repair detailed. In this process includes many factors that must be taken first during design and implementation of repairing any details, and includes:

* Visual control,

* Compiling process technology

* Thermal processing

* Control of hardness detail before repair

* Establishment of the details that will be repaired

Spoon various forms of excavator are presented in the following figures, (fig. 1.).

[FIGURE 1 OMITTED]

6. QUALITY CONTROL OF DETAILS AFTER

WELDING REPAIR

Welding as a process is pretty complex and multidisciplinary. During its use it is required carefully and accurately the proper technique and right welding parameters to be selected and the welder to be professionally prepared as well. Despite the will that those and the other factors to be chosen in the best way possible, still it is impossible for mistakes to not happen. That's why in the repaired details, mistakes of different types are shown. This inevitable implies the need of the control of repaired details. Quality control of repaired details is very important and is done to make sure if the repaired detail fulfills the necessary technical conditions to return back in the working process (Bytyqi & Osmani, 2002). Control of details after repair includes:

* Visual Control

* Control of mechanical properties

* Control of chemical composition

* NDT methods such are; visual, penetrant liquid, ultrasound, magnetic, etc.

6.1 Hardness measurement of details after welding repair

Welding repair of machinery details besides the purpose to improve the geometrical form and obtain again the desirable fits, it also raises the hardness of them. In Palaj, to measure the hardness of repaired details is used the Unit MIC 10 Krautkramer (figure 2). Before measurement, it is necessary that details to be cleaned. Three or more consecutive measures are done and in the end are found the average value. Image of MIC 10 and the way of measuring the hardness of different details is given in the following figure (Gashi et al., 2008).

[FIGURE 2 OMITTED]

7. CONCLUSION

Kosova Power Corporation (KPC) and its department "Kosovamont" in Palaj-Kastriot use welding repair of coal mining excavator spoon an other details is very successfully as it is shown in this study. Because of the economical problems the corporation has right know and because of the urgency that productivity of power needs, corporation is forced to repair most of the damaged details instead to bi them new. Comparing with the other methods of repairing, welding repair has some advantages such are:

-Economical; all the process of repair is nit very expensive and is pretty good way of repair details for countries with low or average development, (Ramaj, 2007),

-Technical; doesn't require expensive equipments,

-Quality; the quality of repair is sufficient and meets the technical standards required in the beginning of the process. Based on my researches that i have done in Palaj, most of the details that were repaired by welding successfully are incorporated in working process and their working hours after repair satisfy the expenses.

8. REFERENCE

Bytyci, B. & Osmani H. (1996). Welding 1, FIM, Prishtina

Bytyci, B. & Osmani H. (2002). Welding 2, FIM, Prishtina

Gashi, G.; Ramaj, V.;.Bytyqi, B. & Osmani, H. (2007). Quality control of weld repaired details in Palaj-Kastriot, Kosova, 12th International research / expert conference "Trends in the development of machinery and associated technology"

TMT 2008, 26-30 August, 2008. Istambull, Turkey.

Ramaj, V. (2007). " The impact of base and filler material in the quality of weld repair of shafts and axis". Master theme, Prishtine, September, 2007.

Ramaj, V.;. Bytyqi, B.; Osmani, H. & Kacani, J. (2007). Repairing of gear box with welding in the Kosovamont, Proceedings of the 18th International DAAAM Symposium, Katalinic, B. (Ed.), pthp 635-637, ISBN 3-901509-58-5, Zadar, Croatia, 24-27* October, DAAAM International Vienna, Vienna 2007

Tab. 1. Parts spoon for coal

Spoon for coal SRS 470 (R0-7) Mirash

Nr. Labels Material Dimension Pie
 ed ces

1. Axis of before Ck45 [PHI]85x210 2
2. Fuses the axis St 37-3 [PHI]12x120 2
3. Rib reinforcement St 37-3 80x80x1030 2
4. Fuses the tooth St 60-2 [PHI]12x15 6
5. Wedge for teeth C0545 20x70x165 6
6. The tooth socket 25CrMo 20x165x250 6
 4
7. The tooth during Cr-Ni- 82x120x391 6
 Mo
8. Holders of before St 52-3 15x180x830 2
9. Connector St 37-3 12x70x265 2
10. Wrapping the St 37-3 12x70x720 2
 spoon
11. Upper plate St 37-3 15x507x845 2
12. Lower plate St 37-3 15x160x210 1
13. Frontal plate St 37-3 15x70x210 1
14. Knife St 60-2 40x420x107 1

Tab. 2. Chemical composition

Material Chemical composition, %

DIN C Si Nmax Pmax Smax

St 37-3 0.17 -- 0.009 0,045 0,045

Tab. 3. Mechanical properties

Material Mechanical properties

DIN Rv, N/[mm.sup.2] Rm, N/[mm.sup.2] A, % Z, %

St 37-3 240 370-450 25 35

Tab. 3. Chemical composition of filing materials

Material C Si Mn P S

VAC 60 0.08 0.90 1.50 0.025 0.025

Tab. 4. Mechanical properties of filing materials

 [R.sub.p] Rm
Material [N/[mm.sub.2]] [N/[mm.sub.2]] [A.sub.5][%] [A.sub.v] [J]

VAC 60 410-490 510-640 >22 >47

Tab. 5. Hardness control of some weld repaired details
measured in Palaj

 Hardness

 After
 Basic Before After heat
Details Material repair repair treatment

1 Coal mining
 excavator spoon St 57-3 32HRc 38HRc 45HRc

2 Shaft [PHI] 247 x 1097
 mm of the gear box 42CrMoS4 22 HRc 25 HRc 30 HRc
 SRS 400

3 Bearing housing of
 active tumbler 42CrMo4 19 HRc 22 HRc
 [PHI]800 x 2100 mm

4 Shaft (c)215x1560
 mm of the main Ck60 23 HRc 28 HRc 38 HRc
 wheel of gear box

5 Electromotor shaft Ck45 18 HRc 23 HRc
 315 kW