Patent Publication Number: US-11040438-B2

Title: Hammer drill

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application claims priority, under 35 U.S.C. § 119, to UK Patent Application No. 18 124 37.0 filed Jul. 31, 2018. 
     FIELD 
     The present invention relates to a hammer drill. 
     BACKGROUND 
     Hammer drills are capable of supporting a cutting tool in a tool holder and comprise a hammer strike mechanism which reciprocatingly strikes the rear end of the cutting tool to repetitively urge the cutting tool forward in a direction parallel to the longitudinal axis of the cutting tool. The hammer strike mechanism typically comprises a cylinder in which is mounted a piston which can be reciprocatingly driven by a hammer drive mechanism which translates the rotary drive of a motor to a reciprocating drive of the piston. A ram, also slideably mounted within the cylinder, forward of the piston, is reciprocatingly driven by the piston due to successive over and under pressures in an air cushion formed within the cylinder between the piston and the ram. The ram repeatedly impacts a beat piece slideably located forward of the ram either within the cylinder or forward of the cylinder, which in turn transfers the forward impacts from the ram to the cutting tool releasably secured, for limited reciprocation, within the tool holder at the front of the rotary hammer. When a hammer drill only comprises a hammer strike mechanism, the hammer drill can only operate in a hammer only mode. An example of such a hammer is a pavement breaker. EP1872908 discloses such a pavement breaker. 
     Other types of hammer drill can operate in two modes of operation, namely a hammer only mode or a hammer and drill mode, or in three modes of operation, namely a hammer only mode, a drill only mode, or a hammer and drill mode. Hammer drills of these type typically comprise a hammer spindle mounted for rotation within a housing which can be selectively driven by a rotary drive mechanism within the housing. The rotary drive mechanism is driven by a motor also located within the housing. The hammer spindle rotatingly drives a tool holder of the rotary hammer which in turn rotatingly drives a cutting tool, such as a hammer bit or a drill bit, releasably secured within it. Within the hammer spindle is generally mounted a piston which can be reciprocatingly driven by a hammer drive mechanism which translates the rotary drive of the motor to a reciprocating drive of the piston. A ram, also slidably mounted within the hammer spindle, forward of the piston, is reciprocatingly driven by the piston due to successive over and under pressures in an air cushion formed within the hammer spindle between the piston and the ram. The ram repeatedly impacts a beat piece slidably located within the hammer spindle forward of the ram, which in turn transfers the forward impacts from the ram to the cutting tool releasably secured, for limited reciprocation, within the tool holder at the front of the rotary hammer. A mode change mechanism can selectively engage and disengage the rotary drive to the hammer spindle and/or the reciprocating drive to the piston. Thus, in the hammer only mode, there is only the reciprocating drive of the piston, in the drill only mode, there is only the rotary drive of the hammer spindle, and in the hammer and drill mode, there are both the rotary drive of the hammer spindle and the reciprocating drive of the piston. The specification of EP 0 975 454 al discloses a hammer drill which can operate in three modes of operation. 
     The hammer drive mechanisms for hammer drills comprise a conversion mechanism which converts the rotary movement of a drive shaft driven from the motor into a reciprocating movement of a rod which reciprocatingly drives the piston. Two designs of such a mechanism are typically employed. 
     The first type comprises a crank mechanism. A crank mechanism comprises a drive shaft on which is mounted an eccentric pin. Rotation of the drive shaft results in the eccentric pin rotating around the axis of rotation of the drive shaft, the eccentric pin moving in a circumferential direction around the axis. One end of a connecting rod attaches to the eccentric pin. The other end of the connecting rod attaches to the piston. The rotational movement of the eccentric pin around the axis of the crank shaft results in a reciprocating limited to a forward/rearward movement within the cylinder or spindle). The design and operation of such crank mechanisms is well known and therefore is not described movement of the piston within the cylinder or spindle (the movement of the piston being in any further detail. EP1872908 discloses a hammer drill having such a crank mechanism. 
     The second type comprises a wobble bearing. A wobble bearing comprises a wobble plate mounted on a drive shaft. A rod is attached to the side of the wobble plate and projects radially from the wobble plate. The wobble plate slideably engages with an angled groove or guide which is formed around the outer surface of the drive shaft and which extends in a plane, the plane being located at an angle to the longitudinal axis of the shaft. The wobble plate is prevented from rotating around the axis of the drive shaft. As such, rotation of the drive shaft causes the wobble plate to reciprocatingly drive the rod about an axis perpendicular to the longitudinal axis of the rod in a direction parallel to the axis of the drive shaft. The end of the rod remote from the wobble plate is attached to the piston. As such, the reciprocating movement of the arm results in a reciprocating movement of the piston. The design and operation of such wobble bearings is well known and therefore is not described in any further detail. EP1157788 discloses a hammer drill with a hammer drive mechanism comprising a wobble bearing. 
     A hammer cycle is when the drive shaft of a crank mechanism or a wobble bearing rotates through 360 degrees. During a hammer cycle, the piston will travel forward from its most rear position within a cylinder or spindle to its most forward position and then back again to its most rearward position. During a hammer cycle, the piston is driven forward in order to push the ram forward via an air cushion of increased air pressure to strike a beat piece which in turn strikes a cutting tool. The beat piece and ram subsequently rebound, with the ram then being drawn rearwardly by the piston which is moving in a rearward direction, due to a decrease in air pressure between the piston and the ram, to its rearmost position where the hammer cycle can commence again. The operation of hammer strike mechanisms is well known and therefore is not described in any further detail. 
     During a hammer cycle, different pressure loads are applied to the piston. This results in the torque applied by the drive shaft changing throughout a hammer cycle. The peak driving torque during a hammer cycle can be up to eight times higher than the overall average driving torque over a hammer cycle. This results in increased wear on component parts of the hammer strike mechanism and other component parts of the hammer drill. 
     SUMMARY 
     It is therefore the object of the present invention to reduce the peak loads of the drive torque throughout a hammer cycle to reduce the amount of variation of the drive torque experienced by component parts of the hammer strike mechanism. This will reduce the amount wear on the component parts. Furthermore, as the variation in drive torque over a hammer cycle is reduced, the size of the component parts of the hammer strike mechanism can be reduced. 
     Accordingly, there is provided a hammer drive mechanism in accordance with claim  1 . 
     The use a dampener within a drive shaft of a hammer drive mechanism absorbs some of the energy when the peak driving torque is experienced by the hammer drive mechanism during a hammer cycle and subsequently releases it during other parts of the hammer cycle to smooth out the variation in the drive torque experienced by the hammer drive mechanism over a hammer cycle. 
     The dampener can be made from resiliently deformable material, or may be a mechanical spring or any other type of spring, such as a pneumatic spring, or material which exhibits spring like properties. The dampener may be a compound dampener made from a combination of individual dampeners. The dampening properties may be linear or variable over the range of angular positions of the two parts. 
     Within the scope of this application it is expressly envisaged that the various aspects, embodiments, examples and alternatives set out in the preceding paragraphs, in the claims and/or in the following description and drawings, and in particular the individual features thereof, may be taken independently or in any combination. Features described in connection with one embodiment are applicable to all embodiments, unless such features are incompatible. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Three embodiments of the present invention will now be described, by way of example only, with reference to the accompanying figures, in which: 
         FIG. 1  shows a perspective view of a hammer drill; 
         FIG. 2  shows a side view of the hammer strike mechanism with a crank mechanism and the rotary drive mechanism according to the first embodiment; 
         FIG. 3  shows a horizontal cross-sectional view of the hammer strike mechanism and rotary drive mechanism; 
         FIG. 4  shows a partial side view of the hammer strike mechanism and rotary drive mechanism with the two-part drive shaft being visible; 
         FIG. 5A  shows an exploded view of the two-part drive shaft; 
         FIG. 5B  shows a perspective view of the assembled two-part drive shaft; 
         FIG. 6  shows a side view of the assembled two-part drive shaft; 
         FIG. 7  shows a cross sectional view of the two-part drive shaft in the direction of Arrows A in  FIG. 6 ; 
         FIG. 8  shows a side view of the assembled two-part drive shaft of a crank mechanism according to a second embodiment of the present invention; and 
         FIG. 9  shows a side view of the assembled two-part drive shaft of a wobble bearing according to a third embodiment of the present invention. 
     
    
    
     DETAILED DESCRIPTION 
     A first embodiment of the present invention will now be described with reference to  FIGS. 1 to 7 . 
     A hammer drill is shown in  FIG. 1 . The represented rotary hammer has a hammer housing  1  which forms a gripping portion  3  at its rear end. A switch actuator  5  for switching an electric motor (not shown) of the hammer drill on and off projects into a grip opening  9 . The grip opening  9  is defined at its rear side by the gripping portion  3 . In the rear lower portion of the gripping portion  3 , a mains lead  102  which serves to connect the hammer drill to a power source, is led out. It will however be appreciated that the hammer drill may be powered by a battery pack which attaches to the housing  1  or grip  3 . 
     Located in the upper portion of the hammer drill shown in  FIG. 1  is an inner housing  11 , formed of half-shells and made from cast aluminium or the like in which a hammer spindle  13  is rotatably housed (see  FIG. 2 ). The rear end of the hammer spindle  13  forms a guide tube  15 , provided in known manner with vent apertures, for a pneumatic hammer strike mechanism, and at the front end of which a tool holder  17  is held. The hammer mechanism contains a piston  19  which is coupled, via a trunnion  21  housed in it and a connecting rod  23 , with a rigid crank pin  25  which sits eccentrically on the upper plate-shaped end  27  of a two-part drive shaft  29  which is described in more detail later (see  FIG. 3 ). A reciprocating movement of the piston  19  is carried out to alternately create a vacuum and an over-pressure in front of it, in order to move a ram  31  situated in the guide tube  15  correspondingly, so that this transmits impacts onto a beat piece  33 , which passes them on to the rear end of a hammer bit, drill bit or chisel bit (not shown), which is inserted into the tool holder  17 . This mode of operation and the structure of a pneumatic hammer strike mechanism are known and will therefore not be explained in more detail. 
     The electric motor is arranged in the hammer housing  1  in such a way that its armature shaft (not shown) extends substantially perpendicular to the longitudinal axis of the hammer spindle  13  and the tool holder  17 . Also, the longitudinal axis of the armature shaft preferably lies in a plane with the longitudinal axis of the hammer spindle  13  and the tool holder  17 . 
     To drive the hammer strike mechanism, at the upper end of the armature shaft, a pinion (not shown) is formed which meshes with a first gear wheel  39  rigidly mounted on a first rotatable shaft  30 . 
     A second gear wheel  104  is mounted on the first rotatable shaft  30  in a freely rotatable but non-axially slideable manner. 
     The second gear wheel  104  meshes with a third gear wheel  41  rigidly mounted on a second rotatable shaft  43  in a non-rotatable manner. At the upper end of the second shaft  43 , a bevel gear  106  meshes with the bevel teeth  45  of a drive sleeve  47 . The drive sleeve  47  is rotatably mounted but axially non-displaceable on the hammer spindle  13  or on its rear part forming the guide tube  15  of the hammer mechanism. A coupling sleeve  49  is mounted in an axially displaceable but non-rotatable manner on the hammer spindle  13  in front of the drive sleeve  47  as a result of engagement with a splined section  108  on the outer surface of the hammer spindle  13 . The coupling sleeve  49  can be displaced between a position of driving engagement, via teeth or projections (not shown) formed at its rear end, with corresponding teeth or projections (not shown) at the front end of the drive sleeve  47 , and a forwardly displaced position in which there is no engagement between the coupling sleeve  49  and the drive sleeve  47 . A helical spring (not shown) loads the coupling sleeve  49  in the direction of the drive sleeve  47 . The spring loading causes the coupling sleeve  49  to be biased into the position of driving engagement with the drive sleeve  47 . The coupling sleeve  49 , the drive sleeve  47  and the spring act as a torque clutch which operates in the well-known manner. 
     Thus, rotation of the third gear wheel  41  causes rotation of the second shaft  43  which in turn causes rotation of the drive sleeve  47 . And, when there is a positive engagement between drive sleeve  47  and the coupling sleeve  49 , the hammer spindle  13  and the tool holder  17  are also rotated. 
     To drive the hammer strike mechanism, the first gear wheel  39  driven by the pinion of the armature shaft  35  is coupled with the drive shaft  29  in a manner yet to be described so that the crank pin  25  performs a circular movement which creates, via the connecting rod  23 , the reciprocating movement of the piston  19  in the guide tube  15  of the hammer mechanism. 
     A sleeve-shaped coupling part  55  is non-rotatably mounted (through engagement with a splined section) but axially displaceable on the first shaft  30  and has an annular groove  57  formed around its periphery. At the lower end, the sleeve-shaped coupling part  55  has projections or teeth (not shown). In the lowest position of the sleeve-shaped coupling part  55  on the first shaft  30 , the teeth are in positive engagement with corresponding recesses (not shown) in the second gear wheel  104 . In this position, rotation of the first gear wheel  39  rotates the first shaft  30  which is in positive engagement with the sleeve-shaped coupling part  55 , which in turn rotates the second gear wheel  104 . 
     The drive shaft  29  is supported in a bearing  160  and is located in axial alignment with the first shaft  30 . The lower end of the crank shaft  29  comprises a series of teeth  110 . At its upper end, the sleeve-shaped coupling part  55  has a second set of projections or teeth (not shown). In the upper position of the sleeve-shaped coupling part  55  on the first shaft  30 , the second set of teeth are in positive engagement with corresponding teeth  110  of the drive shaft  29 . In this position, rotation of the first gear wheel  39  rotates the first shaft  30  which is in positive engagement with the sleeve-shaped coupling part  55 , which in turn rotates the drive shaft  29 . 
     The sleeve coupling part  55  can be axially slid, using a mode change mechanism  112 , on the first shaft  30  between three positions, a first lower position where it is in driving engagement with the second gear wheel  104  but disengaged from the drive shaft  29 , a second middle position where it is in driving engagement with the second gear wheel  104  and the drive shaft  29 , and a third upper position where it is disengaged from the second gear wheel  104  but is drivingly engaged with the drive shaft  29 . When the sleeve coupling part  55  is axially slid, to the first lower position, rotation of the first gear wheel  39  results in the operation of the rotary drive mechanism but no operation of the hammer strike mechanism (drill only mode). When the sleeve coupling part  55  is axially slid to the second middle position, rotation of the first gear wheel  39  results in the operation of both the rotary drive mechanism and the hammer strike mechanism (drill and hammer mode). When the sleeve coupling part  55  is axially slid to the third upper position, rotation of the first gear wheel  39  results in no operation of the rotary drive mechanism but the operation of the hammer strike mechanism (hammer only mode). 
     The mode change mechanism  112  moves the sleeve coupling part  55  by the vertical movement of a plate  116  using a mode change knob  118 . Mode change mechanisms are well known in the art and therefore no further details will be described. 
     The two-part drive shaft  29  will now be described in further detail with reference to  FIGS. 5, 6 and 7 . 
     The drive shaft  29  comprises two parts, a first rigid upper part  120  and a second rigid lower part  122 . 
     The first upper part  120  comprises the upper plate-shaped end  27  on which is mounted the crank pin  25 . The crank pin  25  is mounted eccentrically to the axis of rotation  124  of the drive shaft  29  and extends in a direction which is parallel to the axis  124  of rotation. A circular aperture  126  is formed through the upper plate-shaped end  27  in a symmetrical manner around the axis of rotation  124 . Formed on the underside of the upper plate-shaped end  27  are two projections  128  (see  FIG. 7 ). The two projections  128  have a uniform depth X and are of the same shape arranged in a symmetrical manner around the axis of rotation  124 . The shape of the cross section of each projection is that of a trapezium where the two parallel sides are arcuate as best seen in  FIG. 7 . Each projection  128  extends circumferentially less than 90 degrees around the underside of the upper plate-shaped end  27  so that the gaps between the projections in a circumferential direction are greater in length than the length of the projections  128 . 
     The second lower part  122 , in a direction parallel to the direction of the axis of rotation  124 , comprises three sections. The first lower section comprises a tubular body  130  on which are formed the teeth  110 . The second middle section comprises a circular plate  132  which extends radially from the axis of rotation  124  in a symmetrical manner. The third section comprises a tubular extension  134  which surrounds the axis of rotation  124  in a symmetrical manner. The height of the tubular extension  134  is X. A tubular aperture  136  extends through the tubular extension  134  and circular plate  132  and into the tubular body  130 . The tubular aperture  136  is threaded. Formed on the upper surface of the circular plate  132  are two projections  138 . The sides of the projections  138  merge with the tubular extension  134 . The two projections  138  also have a uniform depth X and are of the same shape arranged in a symmetrical manner around the axis of rotation  124 . The shape of the cross section of each projection  138  is that of a trapezium where the two parallel sides are arcuate as best seen in  FIG. 7 . Each projection  138  extends circumferentially less than 90 degrees around the top surface of the circular plate  132  so that the gaps between the projections  138  in a circumferential direction are greater in length than the length of the projections  138 . 
     Sandwiched between the two parts  120 ,  122 , when the two parts are assembled, are two dampeners  140  made from resilient deformable material such as rubber. Each dampener  140  comprises two square pegs  142  interconnected with an arcuate tether  144  formed in a one-piece construction. The height of the square pegs  142  is X. 
     When the drive shaft  29  is assembled, the upper part  120  is placed on top of the lower part  122  so that the projections  128  on the upper part  120  are located between the projections  138  on the lower part  122  in an alternate manner. The two dampeners  140  are sandwiched between the two parts  120 ,  122  so that each square peg  142  of the dampeners  140  locates between a projection  128  from the upper part  120  and a projection  138  of the lower part so that adjacent projections  128 ,  138  are separated by a square peg  142 . The size of the cross section of each square peg  142  is such to fill the gap between each pair of adjacent projections  128 ,  138 . When the drive shaft  29  is assemble, the projections  128 ,  138  are arranged on a circular path around the axis of rotation  124  of the drive shaft ( 29  in the alternate manner. When no rotational torque is applied on the drive shaft  29 , the projections  128 ,  138  and square pegs  142  are arranged in a symmetrical manner around the axis of rotation  124  as shown in  FIG. 7 . 
     A bolt  146  passes through the circular aperture  126  formed through the upper plate-shaped end  27  and screws into the threaded tubular aperture  136  sufficiently tightly to hold the upper and lower parts  120 ,  122  together whilst enabling the upper part  120  to rotate (Arrows M and N) about the axis of rotation  124  relative to the lower part  122 , two of the square pegs  142  being compressed as it does so. 
     During the operation of the hammer strike mechanism, the lower part  122  of drive shaft  29  is rotationally driven about the axis of rotation  124  via the teeth  110 . The lower part  122  transfers the rotary movement to the upper part  120  via the projections  138  of the lower part  122  transferring the rotational force via the square pegs  142  of the dampener  140  to the projections  128  on the upper part  120  which in turn transfers the rotational force to the crank pin  25 . 
     During the hammer cycle the force exerted on the piston  19  and hence on the crank pin  25  changes. As the force changes, the rotational torque transferred across the dampeners  140  changes. The compression of the dampeners  140  allow limited rotational movement (Arrows M and N) between the upper part  120  and lower part  122  due to the compression and expansion of the square pegs  142  between the projections  128 ,  138  as the upper part  120  moves relative to the lower part  122 . The compression and expansion of the square pegs  142  of the dampeners  140  absorbs, across a hammer cycle, some of the variation in the torque experienced in the hammer drive mechanism. 
     When no rotational torque is applied on the drive shaft  29 , it can be arranged that the square pegs  142  experience no compressive force, two of the square pegs  142  becoming more compressed when there is limited rotational movement (Arrows M and N) between the upper part  120  and lower part  122 . Alternatively, when no rotational torque is applied on the drive shaft  29 , it can be arranged that the square pegs  142  already compressed, two of the square pegs  142  becoming more compressed when there is limited rotational movement (Arrows M and N) between the upper part  120  and lower part  122 , the other two becoming less compressed. 
     Whist the dampener in the first embodiment is made from a resiliently deformable material, it will be appreciated by reader that the dampener could be manufactured as a mechanical spring. It will further be appreciated that the dampener can be a combination of individual dampeners. 
     A second embodiment of the present invention will now be described with reference to  FIG. 8 . Where the same features are present in the second embodiment are present in the first embodiment, the same reference numbers have been used. The only difference between the first embodiment and the second embodiment is that the design of the crank pin  25 . In the first embodiment, the crank pin  25  was made from a single rigid material such as steel. In the second embodiment, the crank pin is made from two parts, a first part  200  which is rigidly mounted on the upper plate-shaped end  27  and a second part  202  which attaches to the end of the connecting rod  23 . The first and second parts  200 ,  202  are connected to each other by a dampener  204  made from a resilient deformable material. 
     During the hammer cycle the force exerted on the piston  19  and hence on the second part  202  of the crank pin  25  changes. As the force changes, the dampener  204  compresses and expands, absorbing some of the variation in the torque experienced in the hammer drive mechanism. 
     In the second embodiment, the design of the crank pin comprising two parts  200 ,  202  is shown being using in conjunction with the two-part drive shaft  29  comprising dampeners  140 . It will be appreciated that the design of the crank pin comprising two parts  200 ,  202  can be used on its own with a drive shaft comprising a single component with no dampeners and still absorbing some of the variation in the torque experienced in the hammer drive mechanism over a hammer cycle. 
     A third embodiment of the present invention will now be described with reference to  FIG. 9 . Where the same features are present in the third embodiment are present in the first embodiment, the same reference numbers have been used. The only difference between the first embodiment and the third embodiment is that the conversion mechanism is a wobble bearing  300 . 
     The wobble bearing  300  comprises a wobble plate  302  which slideably engages, using ball bearings (not shown) with an angled groove (not shown) which is formed in the surface of the drive shaft and extends around the circumference of the drive shaft  29 . The groove locates within in a plane  304 , the plane  304  being located at an angle to the longitudinal axis of the shaft  29 . A rod  306  is attached to the side of the wobble plate and projects radially from the wobble plate  302 . The wobble plate is prevented from rotating around the axis of the drive shaft  29 . As such, rotation of the drive shaft  29  causes the wobble plate  302  to reciprocatingly drive the rod about an axis perpendicular to the longitudinal axis of the rod  306  in a direction (Arrow Q) parallel to the axis of the drive shaft. The design of wobble bearings is well known and therefore no further design details are provided. 
     The drive shaft is constructed in two parts  308 ,  310  with dampeners  140  sandwiched between them. The design of the connecting portions of the two parts  308 ,  310  and the dampeners  140  are the same as those in the first embodiment and function in the exact same manner. 
     The design of the rod  306  is made from two parts, a first part  312  which is rigidly mounted on wobble plate  302  and a second part  314  which connects to the piston. The first and second parts  312 ,  314  are connected to each other by an dampener  316  made from a resilient deformable material. 
     During the hammer cycle the force exerted on the piston  19  and hence on the second part  314  of the rod  306  changes. As the force changes, the dampener  316  compresses and expands, absorbing some of the variation in the torque experienced in the hammer drive mechanism. 
     In the third embodiment, the design of the rod  306  is shown as comprising two parts  312 ,  314  joined by a dampener  316 . It will be appreciated that the design of the rod  306  could comprise a single component with no dampeners, the drive shaft  29  with dampeners  140  still absorbing some of the variation in the torque over a hammer cycle experienced in the hammer drive mechanism. 
     It will be appreciated by persons skilled in the art that the above embodiments have been described by way of example only and not in any limitative sense, and that various alterations and modifications are possible without departure from the scope of the invention as defined by the appended claims. 
     Individual elements or features of a particular embodiment are generally not limited to that particular embodiment, but, where applicable, are interchangeable and can be used in a selected embodiment, even if not specifically shown or described. The same may also be varied in many ways. Such variations are not to be regarded as a departure from the disclosure, and all such modifications are intended to be included within the scope of the disclosure. 
     Example embodiments are provided so that this disclosure will be thorough, and will fully convey the scope to those who are skilled in the art. Numerous specific details are set forth such as examples of specific components, devices, and methods, to provide a thorough understanding of embodiments of the present disclosure. It will be apparent to those skilled in the art that specific details need not be employed, that example embodiments may be embodied in many different forms and that neither should be construed to limit the scope of the disclosure. In some example embodiments, well-known processes, well-known device structures, and well-known technologies are not described in detail. 
     The terminology used herein is for the purpose of describing particular example embodiments only and is not intended to be limiting. As used herein, the singular forms “a,” “an,” and “the” may be intended to include the plural forms as well, unless the context clearly indicates otherwise. The terms “comprises,” “comprising,” “including,” and “having,” are inclusive and therefore specify the presence of stated features, integers, steps, operations, elements, and/or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and/or groups thereof. The method steps, processes, and operations described herein are not to be construed as necessarily requiring their performance in the particular order discussed or illustrated, unless specifically identified as an order of performance. It is also to be understood that additional or alternative steps may be employed.