Login| Sign Up| Help| Contact|

Patent Searching and Data


Title:
METHOD AND DEVICE FOR IMPROVING ABRASIVE WEAR RESISTANCE OF SIDE PROFILES OF MINE SCRAPER CHAIN CONVEYOR PANS
Document Type and Number:
WIPO Patent Application WO/2019/098862
Kind Code:
A1
Abstract:
The method for improving abrasive wear resistance of side profiles of mine scraper chain conveyor pans consists in that the wear zone of the inner plane (1b) of side profile (1a) is subjected to flame hardening consisting in that prior to the proper flame hardening process, the speed parameters of advance of an automatic welding machine (3) are determined by trial method until the hardness of the hardened surface is between 300 and 400 HV, and then the process parameters thus determined are set on the advance speed controller of the automatic welding machine (3a) and on the quenching fluid speed controller (13b), after which the final process of flame hardening is conducted. The device according to the invention includes a quenching tank (2) with a guide rail (4) for an automatic welding machine (3) arranged on the right edge of the tank, and also includes a base (9) on the opposite side, to which base an arrangement for fastening the side profile (1a) is attached. The automatic welding machine (3) is provided with at least two gas burner nozzles (12) and two gas supply conduits (10), and with at least two quenching fluid nozzles (14) of the quenching system connected by means of a quenching fluid supply pipe (11). In addition, the automatic welding machine (3) is provided with a controller (3a) of the automatic welding machine advance speed, with a quenching fluid speed controller (13b) and with a flame controller (15a), whereas gas is supplied by means of a conduit (24) from an external gas tank (25). The quenching fluid (13) is supplied to the automatic welding machine (3) from equalising tank (16) by means of a quenching fluid pump (18) and quenching fluid supply conduits (20).

Inventors:
WIECZOREK, Andrzej (ul. Św. Urbana 8/17, Zabrze, PL-41-800, PL)
Application Number:
PL2018/000001
Publication Date:
May 23, 2019
Filing Date:
January 03, 2018
Export Citation:
Click for automatic bibliography generation   Help
Assignee:
PATENTUS S.A. (ul. Górnośląska nr 11, Pszczyna, PL-43-200, PL)
International Classes:
B65G19/28; C21D1/08; C21D1/52; C21D1/667
Foreign References:
CN103387113A2013-11-13
CN203346441U2013-12-18
CN203513733U2014-04-02
PL166263B11995-04-28
Attorney, Agent or Firm:
MAŁACHOWSKI, Marian (Kancelaria Patentowa Marian Małachowski, ul. Batorego 5/6, Bytom, PL-41-902, PL)
Download PDF:
Claims:
Claims

1. A method for improving abrasive wear resistance of side profiles of mine scraper chain conveyor pans consisting in hardening of the area of contact between the pan side profile and the scraper bar characterised in that the wear zone of the inner plane (1b) of the side profile (1a) is subjected to flame hardening, wherein:

• prior to the proper flame hardening process, the speed parameters of advance of an automatic welding machine (3) are determined by specifying its initial speed at 0.3 m/min, and wherein at least two flames (15) burning at the outlet of gas burner nozzles (12) are turned on, and wherein at least two jets of quenching fluid (13a) flowing out of quench nozzles of the quenching system (14) are turned on, and wherein hardness measurement is performed upon completion of the cycle of this process to determine whether the hardness of the hardened surface is between 300 and 400 HV, and wherein penetrant testing is applied to check for hardening cracks.

• if the hardness of the hardened surface is less than 300 HV, another trial is conducted, but this time with the advance speed of the automatic welding machine (3) reduced by 0.05 m/min or with increased quenching fluid (13a) flow rate, and upon completion of the cycle of this process the hardness measurement is performed again to determine whether the hardness of the hardened surface is between 300 and 400 HV,

• if the hardness of the hardened surface is more than 400 HV, another trial is conducted, but this time with the advance speed of the automatic welding machine (3) increased by 0.05 m/min or with reduced quenching fluid flow rate (13a), and upon completion of the cycle of this process the hardness measurement is performed again to determine whether the hardness of the hardened surface is between 300 and 400 HV,

• the trials are conducted until the attained hardness of the hardened surface is between 300 and 400 HV, and then the process parameters thus determined are set on the advance speed controller of the automatic welding machine (3a) and on the quenching fluid speed controller (13b), after which the final process of flame hardening is conducted.

2. A method for improving resistance according to claim 1 characterised in that the heated wear zone of the inner plane of the side profile (1b) is cooled by means of at least two jets of quenching fluid (13) directed onto the cooled surface at an angle of 45 to 50°.

3. A method for improving resistance according to claim 1 or 2 characterised in that the quenching fluid (13) preferably comprises a polymer-containing aqueous solution with a 6% concentrate content.

4. A device for improving abrasive wear resistance of the side profiles of the pans of mine scraper chain conveyors characterised in that it includes a quenching tank (2) with a guide rail (4) for an automatic welding machine (3) arranged on the right edge of the tank, and also includes a base (9) on the opposite side, to which base a vertical flat bar (5) is attached by means of bolts (8), on which bolts flat clamping bars (6) and nuts (7) are slidably mounted, whereas the automatic welding machine (3) is provided with at least two gas burner nozzles (12) and two gas supply conduits (10), and with at least two quenching fluid nozzles (14) of the quenching system and a quenching fluid supply pipe (11) disposed on one of the arms of the machine, in addition the automatic welding machine (3) is provided with a controller (3a) of the automatic welding machine advance speed, with a quenching fluid speed controller (13b) and with a flame controller (15a), whereas the gas is supplied by means of a conduit (24) from an external gas tank (25), the quenching fluid (13) is supplied to the automatic welding machine (3) from an equalising tank (16) by means of a quenching fluid pump (18) and quenching fluid supply pipes (20), while the spent quenching fluid is drained from the quenching tank (2) to the equalising tank (16) by means of supply conduits (21) and quenching fluid drain pump (19), whereas the equalising tank (16) is provided with a quenching fluid agitator (17) driven by means of a drive motor (23).

5. A device according to claim 4 characterised in that the distance between gas burner nozzles (12) and the surface of the wear zone of the inner plane (1b) of the side profile (1a) must not be less than 10 to 20 mm.

6. A device according to claim 4 characterised in that the quenching fluid nozzles (14) of the quenching system are arranged in relation to the surface of the wear zone of the side profile (1a) inner plane (1b) at an angle of 45° to 50°. 12

List of items:

1- scraper chain conveyor pan,

1 - scraper chain conveyor pan in incorrect position,

1a - side profile of scraper chain conveyor pan,

1 b - wear zone of the inner plane of side profile,

1c - scraper bar of scraper chain conveyor,

2 - quenching tank,

3 - automatic welding machine,

3a - controller of advance speed (of automatic welding machine),

4 - guide rail of automatic welding machine,

5 - flat bar for securing side profile,

6 - flat clamping bar,

7 - nut,

8 - bolts,

9 - base of side profile,

10 - gas supply conduits,

11 - quenching fluid supply pipe,

12 - gas burner nozzle,

13 - quenching fluid,

13a - quenching fluid jet,

13b - quenching fluid speed controller,

14 - quenching fluid nozzle of quenching system,

15 - flame,

15a - flame controller,

16 - equalising tank,

17 - quenching fluid agitator,

18 - pump for supplying quenching fluid to the quenching system,

19 - pump for supplying quenching fluid (to the equalising tank),

20 - supply conduits (quenching fluid to quenching system),

21 - supply conduits (quenching fluid to equalising tank),

22 - quenching fluid level,

23 - drive motor,

24 - gas supply system,

25 - external gas tank,

Description:
Method and device for improving abrasive wear resistance of side profiles of mine scraper chain conveyor pans

The invention relates to a method and device for improving abrasive wear resistance of side profiles of mine scraper chain conveyor pans, particularly of conveyors used in mechanised longwall systems.

There are underground mechanised mining systems that include scraper chain face conveyors used for the transport of extracted coal from the wall to a stage loader. The extracted coal is moved by means of scraper bars which are attached to chains, the latter being driven by chain drums. During normal operation there is no contact in the wear zone between the side profile of the pan and the scraper bar which moves over the raceway of the conveyor.

In the case of buckled floor or within the so-called connecting pan zone, adjacent pans become deflected, one of which remains in its proper position, while the other is deflected in relation to the first. The angle of pan orientation changes which results in the occurrence of undesired friction between mating parts. The scraper bar comes into contact with the pan which may lead to accelerated wear of the side profile of the pan. This may eventually lead to a situation wherein the scraper bar is expelled from its guide in the damaged side profiles, creating thereby a safety hazard for people working nearby.

There is a known method of induction hardening of the areas of contact of the side profile with the scraper bar. This method, however, does not enable achieving large hardening depths up to 5 mm, and is applied mainly for rolled side profiles used in stage loaders. The side profiles of face conveyors have additional connecting and sliding surfaces on which the coal shearer moves. In this case surface hardening can be attained using welding methods, either manual or automatic, by applying an abrasion resistant weld overlay. This method, however, is expensive, and is applied to recondition conveyor pans.

The Polish patent specification PL 166263 describes a device for reconditioning worn pans of scraper chain conveyors, wherein at first sealing endpieces of the worn pan are removed, after which the pan is rotated by 180° in the vertical plane. Then dents and bulges are removed from the top plate of the pan and the height difference of its inverted profile is equalised. Finally the sealing endpieces are reattached to the top plate. The device has several working stations with supporting frames of honeycomb structure provided with rollers forming a roller track, the said working stations being releasably joined together.

The object of the present invention is to provide long service life to the side profiles by improving their resistance to abrasive wear by hardening the contact zones thereof with the scraper bars while ensuring high efficiency and cost-effectiveness of the process.

The essence of the method of improving abrasive wear resistance of the side profiles of the pans of mine scraper chain conveyors consists in that the wear zone of the inner plane of the side profile is subjected to flame hardening, wherein prior to the proper flame hardening process, the speed parameters of advance of an automatic welding machine are determined by specifying its initial speed at 0.3 m/min, and wherein at least two flames burning at the outlet of gas burner nozzles are turned on, and wherein at least two jets of quenching fluid flowing out of quench nozzles of the quenching system at a rate of no less than 30 litres/m in are turned on, and wherein hardness measurement is performed upon completion of the cycle of this process to determine whether the hardness of the hardened surface is between 300 and 400 HV, and wherein penetrant testing is applied to check for hardening cracks.

The temperature to which the profile surface is heated should be adapted to the type of material being hardened; the recommended heating temperature is 30 to 50 degrees above the Ac3 temperature of the treated steel. The effect of surface melting leading to surface cracks should be strictly avoided.

If the hardness of the hardened surface is less than 300 HV, another trial is conducted, but this time with the advance speed of the automatic welding machine reduced by 0.05 m/min or with the quenching fluid flow rate increased by 10% in relation to the initial flow rate, and upon completion of the cycle of this process the hardness measurement is performed again to determine whether the hardness of the hardened surface is between 300 and 400 HV. The above steps are repeated until the desired hardness is attained. If the hardness of the hardened surface is more than 400 HV, another trial is conducted, but this time with the advance speed of the automatic welding machine increased by 0.05 m/min or with the quenching fluid flow rate reduced by 10% in relation to the initial flow rate, and upon completion of the cycle of this process the hardness measurement is performed again to determine whether the hardness of the hardened surface is between 300 and 400 HV. The trials are conducted until the attained hardness of the hardened surface is between 300 and 400 HV, and then the process parameters thus determined are set on the advance speed controller of the automatic welding machine and on the quenching fluid speed controller, after which the final process of flame hardening is conducted. In the method described the heated wear zone of the inner plane of the side profile is cooled by means of at least two jets of quenching fluid directed onto the cooled surface at an angle of 45 to 50°. Preferably the quenching fluid comprises a polymer-containing aqueous quench formulated for flame hardening with a 6% concentrate content.

The device for improving abrasive wear resistance of the side profiles of the pans of mine scraper chain conveyors includes a quenching tank with a guide rail for an automatic welding machine arranged on the right edge of the tank, and also includes a base on the opposite side, to which base a vertical flat bar is attached, the flat bar having bolts fastened onto it, the bolts holding nuts and flat clamping bars slidably mounted on the bolts. The automatic welding machine is provided with at least two gas burner nozzles and two gas supply conduits, and with at least two quenching fluid nozzles of the quenching system and a quenching fluid supply pipe disposed on one of the arms of the machine. In addition, the automatic welding machine is provided with a controller of the automatic welding machine advance speed, with a quenching fluid speed controller and with a flame controller. Gas is supplied by means of a conduit from an external gas tank, quenching fluid is supplied to the automatic welding machine from an equalising tank by means of a quenching fluid pump and quenching fluid supply pipes, while the spent quenching fluid is drained from the quenching tank to the equalising tank by means of supply conduits and quenching fluid drain pump, whereas the equalising tank is provided with a quenching fluid agitator driven by means of a drive motor.

The distance between gas burner nozzles and the surface of the wear zone of the side profile inner plane must not be less than 10 to 20 mm. The quenching fluid nozzles of the quenching system are arranged in relation to the wear zone of the side profile inner plane at an angle of 45° to 50°.

The method and device for improving abrasive wear resistance of side profiles of mine scraper chain conveyor pans enable improving that wear resistance in an efficient, automated and cost-effective manner.

The subject of the invention is illustrated in drawings, of which Fig. 1 depicts the side profile of mine scraper chain conveyor pan along with the wear zone of the pan side profile, and Fig. 2 depicts a diagram of the device according to the invention.

Example I

The method for improving abrasive wear resistance of side profiles of mine scraper chain conveyor pans 1 consists in that the side profile 1a of the scraper chain conveyor pan is subjected to flame hardening in an automated and repeatable manner with the use of a device for improving abrasive wear resistance of side profiles of mine scraper chain conveyor pans. The arms of the automatic welding machine 3 are fitted with two gas burner nozzles 12 in such way that they heat in sequence the surface to be hardened within the wear zone of the inner plane of the side profile 1b of the side profile of scraper chain conveyor pan 1a. The distance from this surface must not be less than 10-20 mm. The gas burner nozzles 12 must be arranged in such manner as to avoid merging the flames 15 which could cause putting out one flame by the other. The quenching fluid jet 13 must cool a zone heated by two gas burners, whereas the quenching fluid jet 13a is directed at the surface being cooled an angle of 45° to 50°. The quenching fluid 13 is a polymer-containing aqueous solution with a 6% concentrate content which enables attaining a cooling rate that is higher than the critical cooling rate, which in turn enables obtaining a structure that contains at least 50% martensite. Moreover, the quenching fluid 13 is subjected to regular checks and measures to counteract the proliferation and growth of biological microorganisms that alter its cooling properties. The output of the pump that supplies the quenching fluid to the quenching system 18 enables ample spraying of the quenching fluid 13 to effectively remove heat from the heated surface. The quenching fluid 13 flows down the side profile of the pan 1 a to the quenching tank 2 and is drained by means of supply pump 19 and supply conduit 21 to equalising tank 16 where it cools. The output of the supply pump 19 is so elected that there is no overflow in the quenching tank 2 and there is no shortage of quenching fluid 13 in the tank, with the level 22 of the quenching fluid maintained constant. Additionally, the level 22 of the quenching fluid in the equalising tank 16 is maintained at constant height by means of a make up system shown in Fig. 2.

During the flame hardening process the temperature of the surface being hardened is equal to or higher than the Ac3 temperature of the steel or cast steel being treated. That temperature is usually within the range between 840 and 880°C. Prior to the proper flame hardening process, the speeds of advance of the automatic welding machine 3 are determined. To this end an initial speed of the automatic welding machine 3 of 0.3 m/min is adopted, gas burner nozzles 12 and quenching fluid nozzles 14 of the quenching system are turned on to carry out a trial of hardening in the wear zone of the inner plane of the side profile 1b, i.e. at the point of possible contact with the scraper bar 1c. If surface melting occurs, the advance speed 3 of the automatic welding machine is increased immediately. After the trial, hardness of the hardened surface is measured by means of a portable hardness tester, and penetrant testing is carried out to check for hardening cracks and to determine whether the attained surface hardness is within the range of 300 to 400 HV. If the hardness of the hardened surface is lower, another trial is conducted, but this time at an advance speed of the automatic welding machine 3 reduced by 0.05 m/min or at an increased quenching fluid 13 flow rate. If the hardness of the hardened surface is higher, another trial is conducted, but this time at an advance speed of the automatic welding machine 3 increased by 0.05 m/min or at a reduced quenching fluid 13 flow rate. The trials are repeated until proper surface hardness between 300 and 400 HV is attained. After determining the process parameters, heat treatment of the side profiles 1a is conducted. Upon hardening each side profile 1a, the surface hardness is checked by means of a portable hardness tester i penetrant testing is carried out to check for hardening cracks. In order to harden the area of contact of the pan side profile 1b with the scraper bar (Fig. 1) flame hardening of cast manganese steel with carbon content of 0.3 to 0.35% using an automatic welding machine fitted with a system of two burners and moving at an advance speed of 0,25 m/min and 0.35 m/min. The quenching fluid 13 used is a polymer-containing aqueous solution with a 6% concentrate content. As a result of the process, the structure of tempered martensite or of bainite and martensite with a thickness of at least 3 mm is found in the top layer of the pan side profile 1b, with a 10 mm thick transition layer underneath with a hardness of at least 400 HV. The surface of the profile is characterised by a lower hardness of 370 to 390 HV, which is advantageous, as it reduces wear of the scraper bars which may slide on the side profile within the contact area. Reduced hardness is the effect of flame action which, after conducting hardening, maintains the temperature of the zone adjacent to the hardened zone within a range corresponding to medium temperature tempering. The thickness of the layer hardened to at least 350 HV is ca. 10 mm.

Example II

The device for improving abrasive wear resistance of the side profiles of the pans of mine scraper chain conveyors (Fig. 2) includes a quenching tank 2 with a guide rail 4 for an automatic welding machine 3 arranged on the right edge of the tank, and also includes a base 9 on the opposite side. To the base 9 a vertical flat bar 5 with bolts 8 is attached, the bolts holding flat clamping bars mounted slidably and screwed down with nuts 7. The pan side profile 1a subjected to the process of improving its abrasive wear resistance is mounted between base 9 and flat clamping bars 6. The automatic welding machine 3 is provided with two gas burner nozzles 12 and two liquefied petroleum gas supply conduits 10, and with two quenching fluid nozzles 14 of the quenching system and a quenching fluid supply pipe 11 disposed on one of the arms of the machine. In addition, the automatic welding machine 3 is provided with a controller 3a of the automatic welding machine advance speed, with a quenching fluid speed controller 13b and with a flame controller 15a. Liquefied petroleum gas is supplied from the external gas tank 25 to the automatic welding machine 3 by means of gas supply system conduit 24. The quenching fluid 13 is supplied to the automatic welding machine 3 from equalising tank 16 by means of a quenching fluid pump 18 and quenching fluid supply pipes 20, while the spent quenching fluid is drained from the quenching tank 2 to the equalising tank 16 by means of supply conduits 21 and drain pump 19. The equalising tank is provided with quenching fluid agitator 17 driven by alternating current motor 23. The equalising tank 16 is additionally provided with an automatic make up system (not shown in Fig. 2) which maintains constant level of the quenching fluid 13. The automatic welding machine 3 has an infinitely variable linear advance speed controller 3a, gas burner nozzles adjustably positioned in relation to selected planes of the scraper chain conveyor pan side profile 1a, flame controller 15a and quenching fluid speed controller 13b. Moreover, the distance between gas burner nozzles 12 and the surface of the wear zone of the side profile 1a inner plane 1b must not be less than 10 to 20 mm, and the quenching fluid nozzles 14 of the quenching system are arranged in relation to the wear zone of the side profile 1a inner plane 1b at an angle of 45° to 50°.