AU700739B2

AU700739B2 - Reforged flight bar and method of making the same

Info

Publication number: AU700739B2
Application number: AU20509/95A
Authority: AU
Inventors: William J Ellison; Guy M Maddox Jr.; Brian Lee Simmons
Original assignee: FMC Corp
Current assignee: United Defense LP
Priority date: 1994-06-07
Filing date: 1995-06-06
Publication date: 1999-01-14
Anticipated expiration: 2015-06-06
Also published as: PL308974A1; DE19520727A1; GB2290250B; FR2720671B1; CA2151169A1; GB2290250A; CN1183327A; FR2720671A1; GB9511539D0; RU95109856A; AU2050995A

Description

AUSTRALIA

Patents Act 1990 COMPLETE SPECIFICATION STANDARD PATENT Applicant: FMC CORPORATION Invention Title: REFORGED FLIGHT BAR AND METHOD OF MAKING THE SAME o r r r o o The following statement is a full description of this invention, including the best method of performing it known to me/us: I II I REFORGED FLIGHT BAR AND METHOD OF MAKING THE SAME This invention relates to a flight bar and the method of producing the same, generally, and more particularly, to such a bar which is formed from a worn flight bar and the method therefor.

Flight bars are used in longwall mining equipment, specifically as a component part of the face conveyor incorporated into such equipment. The face conveyor includes a plurality of articulated pans over which flight bars connected to driven chains are pulled to convey the mine material, which has been cut from the face of the seam by the shearer or other mechanism, from the face area to a stage loader for transport and subsequent processing of the mine material. Although the flight bars are typically heavy forgings, the environment in which the operate is abrasive resulting in relatively rapid wear, especially the tips which ride in and are guided by the sigma section of the pans. Significant wear also occurs in the chain bite areas of bars affecting the overall height of the flight bars. In the past a common procedure for repair of worn flight bars has been the welding or "deposition of additional material onto the worn tips, "usually with no repair being made to other areas of the flight bar. Since the tip functions to guide and position :the flight bars, maintaining the proper tip shape is •important, and since the tonnage of coal conveyed decreases as total height of the flight bar decreases, restoration of flight bar height is important. Proper engagement between the chain(s) and the flight bar is critical, and thus restoration of the geometry or configuration in the chain bite areas of the flight bar is also important.

The present invention provides a flight bar and method of making the same which offers restoration of critical features, which permits a consistently more H:\5usan\KeeP\SpeP1\NMO\2050 9 95 fmc corp NMO.doc 12/11/98 11111 1 1B efficient operation of a face conveyor utilizing such flight bars, and which utilizes conventional equipment and processes.

According to the present invention there is provided a method of making a metal flight bar from a worn flight bar which had an original outer configuration said method involving: predetermining an acceptable wear envelope for worn flight bars; measuring a worn flight bar to determine whether it falls within said wear envelope; selecting a worn flight bar having dimensions which place it within said wear envelope; heating the selected flight bar to a predetermined forging temperature; forcing said selected flight bar between dies to form or deepen a pocket adjacent each tip and to urge the metal displaced thereby to fill in the worn areas whereby said selected flight bar assumes said original outer configuration except for the pockets.

According to the present invention there is also provided a reforged flight bar formed by hot forging a worn flight bar said flight bar having a known original outer configuration, said reforged flight bar having an outer configuration substantially identical to said original outer configuration except that the hot forging has either formed pockets or deepened existing pockets thereby i. displacing a volume of metal to substantially replace the :volume missing from said worn flight bar.

30 These and other benefits of the present invention, and many of the attendant advantages thereof, will become more readily apparent from H:\Susan\KeeP\Spei\4NO\20509 95 fcn corp NMO.doc 12/11/98

I

the following description and the accompanying drawings, wherein: Figure 1 is an elevational view of a flight bar according to the present invention showing the bow which clamps the flight bar to the chains; Figure 2 is a view of the flight bar of Figure 1 as viewed from line 2 2 of Figure 1; Figure 3 is vertical section of one the tips of a typical flight bar showing its configuration after having been worn through use, with its original configuration shown in dotted lines; Figure 4 is a bottom view of the tip of the flight bar shown in Figure 3; Figure 5 is a vertical section, similar to Figure 3, of the flight bar shown in Figures 3 and 4 after having been reforged according to the present invention; and Figure 6 is a bottom plan view of the tip portion shown in S"Figure Referring now to Figure 1, there is shown a reforged 20 flight bar, indicated generally at 10, having a pair of left grooves 12 and 14 and a pair of right grooves 16 and 18, each pair contoured to accept a horizontal link of left and right o chains, not shown, respectively. These grooves are frequently referred to as the horizontal chain bite areas. Recesses 20 and S 25 22, which are frequently called the vertical chain bite area and are best seen in Figure 2, are contoured to accept the vertical links on each side of the horizontal chain link seated in the grooves 12 and 14. Similar recesses 24 and 26 are provided to accept the vertical links on each side of the horizontal chain link seated in the grooves 16 and 18. A bow 28 is bolted to the flight bar 10 in a conventional manner to clamp the left and right chains to the flight bar 10. The outer ends or tips 30 and 32 engage complementary grooves called sigma's formed in castings or equivalent structures on each side of- the face conveyor. Recesses called pockets 31 and 33 are formed adjacent each tip 30 and 32, which are provided to reduce the size of billet required for the original forging of the bar 10 and to reduce the weight of the flight bar. The sigma's function to position and guide the flight bar 10 as it is pulled by the chains over the top deck of the pans of the face conveyor during the working movement of the flight bar and during its nonworking return movement. During the working travel, the mined material between the top deck and the flight bar causes the upper portion of the tips 30 and 32 to bear against the sigma causing increased wear on this portion of the tip.

Figures 3 and 4 illustrates a typical wear pattern on the lo tip of another type of flight bar, also indicated at 10, with the original periphery of the bar being shown in dotted lines.

While flight bars of different manufacturers vary, they all share common characteristics, tip portions configure to engage complementary grooves in the pan and chain bites for engagement with the chain or chains. Figure3 5 and 6 show the same type of flight bar shown in Figures 3 and 4 after it has been reforged according to the present invention. The pocket is now deeper than the original pocket 33. The amount of metal displaced by the deeper pocket is slightly greater than 20 the volume of metal abraded or coined from the original flight bar.

Reforging a worn flight bar will be successful only if the bar has not been worn so badly that the amount or volume of metal displaced by deepening the pockets is insufficient to 25 replace the metal lost through wear. It is necessary to determine an envelope of dimensions, based upon the forge dies used for deepening the pockets of a particular type of bar, within which the flight bar must fall. Ideally, the reforging will create a relatively small amount of flash around the entire periphery of the dies to assure that the dies have been completely filled and the resulting reforged bar has the proper configuration. Once it has been determined that a particular flight bar falls within a predetermined envelope, it is heated, such as by induction heating, to a forging temperature of between 2200 and 2400 degrees F. Since the forging will be accomplished in a single strike, the higher temperature is necessary to assure the proper and complete flow of the metal.

-4- The heated bar is then placed in a lower die with its chain bite areas and pockets facing upward. This orientation of the heated bar is preferred because filling the upper die is easier providing a good impression of the chain bite areas. The original pockets will be engaged by the top die, which has greater projections necessary to create deeper pockets. After the forging operation is completed, the bar is removed from the dies and the flash removed. This preferably is accomplished by using appropriate trim dies in a second forge. Since the lo reforging operation causes distortion of the bolt holes in the flight bar, the trim die is also provided with punches to produce cylindrical surfaces for these holes. The second forging operation performs both a punching and a trimming function. The reforged bar is then cleaned, such as by shot S 15 peening, and heat treated to obtain the desired wear resistant and hardness characteristics.

Some flight bars are not provided, as originally S"manufactured, with pockets similar to those shown at 31 and 33. In such cases, instead of deepening existing pockets in the 2o reforging process, new pockets will be formed. The protrusions on the die to form the new pockets will displace sufficient metal to restore the critical areas of the flight bar to their original geometry or configuration, and are positioned to form the new pockets adjacent the tips of the flight bar.

25 While a preferred embodiment of the present invention has been shown and described herein, it will be appreciated that various changes may be made without departing from the spirit of the invention as defined the scope of the appended claims.

Claims

1. A method of making a metal flight bar from a worn flight bar which had an original outer configuration said method involving: predetermining an acceptable wear envelope for worn flight bars; measuring a worn flight bar to determine whether it falls within said wear envelope; selecting a worn flight bar having dimensions which place it within said wear envelope; heating the selected flight bar to a predetermined forging temperature; forcing said selected flight bar between dies to form or deepen a pocket adjacent each tip and to urge the metal displaced thereby to fill in the worn areas whereby said selected flight bar assumes said original outer configuration except for the pockets.

2. The method of claim 1 further involving: removing said selected flight bar from between said dies; trimming any flash created during said forcing step from said selected bar; and heat treating said selected bar to impart the desired metallurgy thereto.

3. The method of either claim 1 or 2 further involving: positioning said selected bar, after heating the same, with the pockets therein facing upward.

4. The method as claimed in any one of claims 1 to 3 wherein said selected bar is heated by induction heating.

A reforged flight bar made in accordance with the method of any one of claims 1 to 4. l: \Susan\Keep\pe\N 0\20509 95 fm corp NNO.doc 12/11190 -1 6

6. A reforged flight bar formed by hot forging a worn flight bar said flight bar having a known original outer configuration, said reforged flight bar having an outer configuration substantially identical to said original outer configuration except that the hot forging has either formed pockets or deepened existing pockets thereby displacing a volume of metal to substantially replace the volume missing from said worn flight bar.

7. A method of making a flight bar from a worn flight bar substantially as described herein with reference to and as illustrated in the accompanying drawings.

8. A reforged flight bar substantially as described herein with reference to and as illustrated in the accompanying drawings. Dated this llth day of November 1998 S 20 FMC CORPORATION By their Patent Attorneys GRIFFITH HACK Fellows Institute of Patent Attorneys of Australia e s *i ii:\Susan\Keep\speci\NMO\20509 95 fmc corp NMO.doc 12/11/98 ~-~1111 i I~'cu~a~,uta~!~odum;~;ii Izrmlla~a jur- i- ABSTRACT A method of making a metal flight bar from a worn flight bar which had an original outer configuration comprising the steps of: predetermining an acceptable wear envelope for worn flight bars; measuring a worn flight bar to determine whether it falls within said wear envelope; selecting a worn flight bar having dimensions which place it within said wear envelope; heating the selected flight bar to a predetermined forging temperature, forcing said selected flight bar between dies to form or deepen a pocket adjacent each tip and to urge the metal displaced thereby to fill in the worn areas whereby said selected flight bar assumes said original outer configuration except for the pockets. *e