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