Dragline Boom

Abstract

A boom uses formed plates instead of a round pipes for the chords of the boom. Each formed plate provides a flat surface for attaching lacings so that complex coping cuts required for round pipe chords can be eliminated. The boom also displaces lacing attachment points so that overlapping welds in previous boom assemblies are also eliminated. The open back of the formed plate and non-overlapping lacing attachment points eliminate hidden welds and obscured mounting surfaces that make inspections and repairs of current boom assemblies difficult or impossible.

What is claimed is: 
     
         1 . A boom for a dragline machine comprising:
 a plurality of chords, each chord having a first mounting surface and a second mounting surface, the first and second mounting surfaces being planar and forming a reflex angle and respective inside surfaces for the first and second mounting surfaces being planar and forming an obtuse angle, each chord being arranged so that at least one of the first and second mounting surfaces are facing and generally parallel with one mounting surface of another of the plurality of chords; and   a plurality of lacings coupling respective facing mounting surfaces of the plurality of chords.   
     
     
         2 . The boom of  claim 1 , wherein at least one of the plurality of chords has a third mounting surface. 
     
     
         3 . The boom of  claim 1 , wherein a weld joint coupling one of the plurality of lacings to the first mounting surface of one of the plurality of chords is non-overlapping with weld joints for other lacings. 
     
     
         4 . The boom of  claim 1 , further comprising an internal lacing coupled between one of the plurality of chords and one of the plurality of lacings, the internal lacing having at least one end with a planar end cut. 
     
     
         5 . The boom of  claim 4 , wherein at least one of the plurality of lacings or internal lacings is a rectangular pipe. 
     
     
         6 . The boom of  claim 1 , wherein the boom further comprises supports disposed between the inside surfaces of the chord and are perpendicular to a length of the chord. 
     
     
         7 . The boom of  claim 6 , wherein at least one support is disposed opposite each point where a lacing is coupled to one of the first and second mounting surfaces and at least one other support is disposed between points where lacings are coupled to one of the first and second mounting surfaces. 
     
     
         8 . A method of making a boom comprising:
 forming a metal plate into a chord having outside surfaces at a reflex angle and inside surfaces at an obtuse angle;   forming additional chords from additional metal plates;   coupling the chord and the additional chords together with lacing so that one outside surface of each chord faces a respective outside surface of one other chord.   
     
     
         9 . The method of  claim 8 , further comprising forming each lacing with a planar end profile. 
     
     
         10 . The method of  claim 8 , wherein coupling the chord and the additional chords with lacing comprises attaching each end of a lacing to the outside surfaces of two facing chords. 
     
     
         11 . The method of  claim 8 , wherein coupling the chord and the additional chords with lacing comprises attaching each end of the lacing so that no lacing is in contact with another lacing. 
     
     
         12 . The method of  claim 8 , further comprising disposing a support between the inside surfaces of the chord. 
     
     
         13 . The method of  claim 12 , wherein disposing the support between the inside surfaces of the chord comprises disposing the support opposite a point where a lacing is attached at a corresponding outside surface. 
     
     
         14 . The method of  claim 12 , wherein disposing the support between the inside surfaces of the chord comprises attaching a formed plate perpendicular to a length of the chord and in full contact with the inside surfaces of the chord. 
     
     
         15 . The method of  claim 12 , wherein disposing the support between the inside surfaces of the chord comprises disposing the support mid-span between lacing attachment points. 
     
     
         16 . A boom for a dragline machine comprising:
 three chords, each chord made from a metal plate formed into three planar surfaces, each chord having at least one obtuse angle between adjacent planar surfaces;   a plurality of inter-chord lacings made of pipes, each end of each inter-chord lacing lying in a single plane, wherein each lacing is attached between facing surfaces of two chords.   
     
     
         17 . The boom of  claim 16 , further comprising a plurality of supports fastened between surfaces of the chord. 
     
     
         18 . The boom of  claim 17 , wherein at least one of the plurality of supports is disposed on the chord opposite each point where a one of the plurality of inter-chord lacings attaches to the chord. 
     
     
         19 . The boom of  claim 16 , wherein each of the plurality of inter-chord lacings are arranged so that the lacings only contact the two chords and no other lacings. 
     
     
         20 . The boom of  claim 16 , wherein an outside surface defines a reflex angle of the chord wherein each of the plurality of inter-chord lacings are coupled to the outside surface of the chord.