Patent Publication Number: US-2022234241-A1

Title: Wood Splitter

Description:
TECHNICAL FIELD 
     The present invention relates to a machine for splitting wood for firewood i.e receiving rounds of firewood and splitting those rounds into smaller pieces, of a size which can conveniently be placed into a log burner. 
     BACKGROUND ART 
     There are numerous different designs of log splitters in the marketplace. A majority of the splitters sold for private use or small-scale commercial use are relatively inexpensive machines which require rounds cut from logs to be manually positioned on a supporting surface and then a wedge-shaped cutter is forced into the round, to split the round in two; the cutter may move horizontally or vertically. 
     A large round may require an initial cut to cut it into two, and then further cuts to cut the two sections down to acceptable firewood sizes. This is relatively slow, and for large rounds of firewood, the work of lifting the round up onto the supporting surface and then handling the sections as they are cut, is heavy work. 
     For firewood contractors who are processing large quantities of firewood, larger scale splitters exist. Most of the larger scale splitters use stationary cutters and force the wood past the cutters rather than pushing the cutters into the wood. 
     One type of larger splitter is capable of forcing an entire large round of firewood through a splitting grid at a single pass. The splitting grid is an array of stationary knives shaped to completely segment the round of firewood. 
     These machines may be efficient, but are expensive to build because of the high pressures involved and also are expensive to operate given the amount of power that is needed to force a large round of wood through a splitting grid in a single pass. 
     Another type of log splitter is known as a “box wedge” splitter: in this type, a round is held in an open top “box” and is pushed through a multi-bladed stationary cutter, so that the sides of the firewood pieces produced are rectangular. 
     Typically, box wedge splitters are somewhat cheaper to build and operate than the cutting grid type of splitter, but it can be difficult to hold a round in the correct position for cutting, and the round may need frequent manual repositioning between cuts. 
     DISCLOSURE OF INVENTION 
     An object of the present invention is the provision of a wood splitter which is capable of processing large rounds of wood into firewood with a minimum of handling, rapidly and safely. 
     The present invention provides a wood splitter which includes: 
     a supporting surface for receiving a section of wood to be split; 
     the supporting surface having a cutting box on one side and a reciprocating moving head on the other side; 
     the cutting box providing a series of spaced stationary knives through which wood can be forced, to cut the wood, said stationary knives including a horizontal knife along the uppermost margin of the cutting box; 
     the moving head being arranged to be reciprocable towards the cutting box so as to engage wood placed on the supporting surface and push said wood through the cutting box, and then away from the cutting box to allow a fresh piece of wood to be placed on the supporting surface; 
     a top plate connected to the moving head by a connecting arm and movable between a first position in which the lower edge of the top plate overhangs said horizontal knife and a second position in which the top plate is raised vertically relative to the cutting box and is moved horizontally away from the supporting surface. 
     Preferably, the top plate is biased towards the moving head by a biasing spring, which may be mounted inside, or alongside the connecting arm. 
     Preferably also, said lower edge of the top plate and said horizontal knife are formed with matching bevels such that as the top plate moved in use between said first and second positions, the lower edge of the top plate travels up the matching bevel of the horizontal knife so as to prevent entry of wood between the top plate and the horizontal knife. 
     In a preferred embodiment of the invention, the cutting box, in addition to said horizontal knife, provides a series of substantially vertical spaced stationary knives which preferably are arranged with an outer knife at each side of the cutting box and three inner knives, one of which is in the centre of the cutting box; preferably the centre knife is beveled on both sides and the remaining vertical knives each are beveled on the outer side. 
     In the preferred embodiment described hereinafter, the wood splitter is powered by a petrol or diesel motor which powers a hydraulic pump; the control system is hydraulically operated and the moving head is reciprocable towards/away from the cutting box by means of a hydraulic ram. 
     However, a wide range of different power and control systems could be used: for example, the wood splitter could be powered by an electric motor which could be battery or mains operated. The electric motor could power the hydraulic pump and hydraulic control system, or an electric motor could be used to reciprocate the moving head towards/away from the cutting box, and an electric control system used. 
     Another possibility would be to use an independent pump system such as a tractor power takeoff (PTO) system and tractor hydraulics. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
       By way of example only, a preferred embodiment of the present invention is described in detail, with reference to the accompanying drawings, in which: 
         FIG. 1  is a diagrammatic side view of a machine in accordance with the present invention; 
         FIG. 2  is a diagrammatic plan view of the machine of  FIG. 1 ; 
         FIG. 2 a    is a plan view similar to  FIG. 2 , but showing an alternative design; 
         FIG. 3  is a side view looking into the cutting box from the exit side of the cutting box; 
         FIG. 4  is a view of the cutting box from above, showing the position of the knives as broken lines; 
         FIG. 5 a    is a side view of part of the machine, showing a detail of the support floor, cutting box and top plate, with the top plate at the start of a cutting operation; 
         FIG. 5 b    is a view similar to  FIG. 5 a    but with the top plate towards the end of a cutting operation; 
         FIG. 6  is a part-sectioned side view showing the moving head and the connecting arm at the start of a cutting operation; 
         FIG. 7  is a view similar to  FIG. 6 , but partway through a cutting operation; and 
         FIG. 8  is a view similar to  FIGS. 6 and 7 , but towards the end of a cutting operation. 
     
    
    
     BEST MODE FOR CARRYING OUT THE INVENTION 
     Referring to the drawings, a wood splitter  10  in accordance with the present invention includes a heavy duty trailer chassis  11  mounted on a pair of spaced wheels  12  and provided with a tow hitch (not visible) at the front of the chassis. It also would be possible to mount the splitter on a stationary chassis which can be positioned e.g. by a forklift. 
     A petrol or diesel powered motor  13  is mounted on the forward part of the chassis and powers a hydraulic pump  14 . The hydraulic pump  14  is supplied with hydraulic fluid from a tank  17  mounted underneath the chassis, between the trailer wheels. Mounting the tank low down on the chassis ensures that the overall weight of the machine is kept as low as possible and the position also helps to protect the tank from accidental damage. However, the tank could be repositioned if necessary, or even positioned separate from the splitter. 
     The hydraulic pump  14  is connected to an hydraulic ram  14 a which operates a moving head  16 , to a further hydraulic ram (not shown) which operates a loading ramp  18 , and to hydraulic control levers; to simplify the drawings, the hydraulic hoses, hydraulic rams, and control levers are not shown, apart from hydraulic hose  15  connected to the ram  14   a.    
     A loading ramp  18  is mounted partway along the length of the machine; only the upper portion of the loading ramp  18  is shown in  FIG. 1 . As shown in  FIG. 2 , the loading ramp consists of a long straight portion  20  and an upturned end portion  21 . The loading ramp  18  is hinged along the upper edge  19  so that it can be pivoted between the lowered position shown in  FIG. 2 , in which the portion  20  extends at a slope over the side of the machine down to the ground, and the upturned end portion lies adjacent the ground, and a raised position in which the portion  20  is raised above the machine, to allow rounds of wood loaded onto the ramp to roll down onto the machine, as hereinafter described. 
     The loading ramp  18  is moved between lowered and raised positions by means of a hydraulic ram (not shown) which is manually controlled by a separate hydraulic control lever (not shown). 
     A discharge chute  22  is pivotally mounted at the rear of the machine, to collect and discharge the split firewood. The chute  22  can be pivoted between an extended position as partially shown in  FIG. 1 , and a position in which the chute is pivoted over the main body of the machine, for compact towing and storage. The chute can be fastened in either of these positions by removable fasteners (not shown). The split firewood collecting on the chute  22  is gradually pushed towards the open end of the chute and can be discharged into any suitable container (e.g. a trailer), or onto the ground. The chute  22  can be fixed in the extended position if the machine is not intended to be towed and/or stored. For some applications, the chute may be omitted altogether. 
     Rounds of wood loaded onto the cutting floor  23  of the machine from the loading ramp  18  are cut one at a time by moving the moving head  16  forwards in the direction of arrow B, to push each round of wood in turn through a rigidly mounted stationary cutting box  24 . 
     The cut pieces of wood are pushed through the length of the cutting box by the pressure of subsequent pieces of cut wood, and are pushed onto the discharge chute  22 . 
       FIG. 3  shows an end on view of the cutting box  24 , viewed from the exit end of the cutting box: there are two spaced outer knives  25 ,  26 , one at each side of the cutting box, and three inner knives, arranged as a centre knife  27  and two intermediate knives  28 ,  29 . The knives  25 - 29  inclusive are equidistantly spaced apart, but are not mounted level to each other: to minimise the load on the hydraulic ram (and thus on the motor  13 ), the outer knives  25 ,  26  are forward of the centre knife  27 , which in turn is forward of the intermediate knives  28 ,  29 . 
     A horizontal beveled knife edge  30  extends along the full length of the top of the cutting box. 
     The outer knives  25 ,  26  and the intermediate knives  28 ,  29  are beveled on the outer side; the centre knife  27  is beveled on both sides. The knives  25 - 29  are vertical, but are angled so that the spacing between adjacent knives increases from the entry into the cutting box to the exit from the cutting box, to make it easier for the wood being cut to pass through the box. 
     The end of the cutting box  24  remote from the moving head  16  is open, to allow the cut wood pieces to pass through the box and onto the chute  22 . 
     The moving head  16  is mounted on the opposite side of the cutting floor  23  to the cutting box  24 , and is connected to a hydraulic ram (not visible) for reciprocating movement towards and away from the cutting box  24 , as indicated by arrows B/C in  FIGS. 2 and 6-8 . The surface of the moving head  16  which lies closest to the cutting box  24  is a flat vertical plate  35  formed with a horizontal groove  35   a  which corresponds in shape and position to the position of the knife edge  30  on the top of the cutting box when the plate  35  lies adjacent the cutting box (see  FIG. 8 ). 
     A bracket  36  is rigidly secured to one side of the moving head  16 ; the bracket surrounds one end of a connecting arm  37 , the other end of which is secured to the supporting frame  39  of a movable top plate  38  which in one position (see  FIG. 5A ) overlies the horizontal knife edge  30  on the top of the cutting box. 
     A biasing spring  40  extends between a bolt  41  mounted across the ends of the bracket  36  and a bolt  42  mounted across the other end of the connecting arm  37 . The connecting arm  37  is hollow, and the biasing spring passes down the length of the arm  37 . The connecting arm  37  protects the biasing spring from debris such as timber shards, and also contains the spring in the event of the spring breaking. 
     Alternatively, as shown in  FIG. 2 a   , the biasing spring  40  may be mounted along the outside of the connecting arm  37 . The connecting arm  37  still offers some protection to the biasing spring from debris, and fitting the biasing spring  40  externally in this way is less expensive to construct, and makes it easier to replace a damaged or broken spring. In this alternative construction, the biasing spring  40  extends between a bolt  41  mounted across the ends of the bracket  36  and a bolt  42   a  mounted on the supporting frame  39  of the top plate  38 . 
     The top plate  38  is mounted on the supporting frame  39  so as to allow the top plate  38  to rise and fall in a vertical plane: a series of spaced bolts  43  each extends between the top plate and the upper part of a bracket  44 ; a further series of spaced bolts  45  extends between the top plate  38  and the lower part of the corresponding bracket  44 . Each of the brackets  44  is arranged to lie in two parallel horizontal slots formed through the supporting frame  39 . The slots are sized to allow the brackets  44  to move vertically within the slots, to allow the top plate  38  to rise and fall in a vertical plane, as hereinafter described. 
     The lower edge  38   a  of the top plate is beveled to match the bevel on the upper surface of the knife  30 , so that when the top plate rises over the knife  30 , the top plate rides smoothly over the bevel of the knife  30 . 
     An adjustable stop  46  is mounted on the machine chassis opposite said one end of the connecting arm  37 . The stop  46  can be adjusted towards or away from the end of the connecting arm  37 , to ensure that the connecting arm  37  stops at a position at which the top plate  38  is correctly positioned relative to the horizontal knife  30 . In addition, it means that the stopping point of the connecting arm  37  can be adjusted over the life of the machine, to allow for wear on the cutting knives. 
     The above described machine is used as follows: the motor  13  is started to power the hydraulic pump  14  and the loading ramp  18  is lowered until the upturned portion  21  lies adjacent to the ground. A round of wood to be split is then loaded onto the ramp  18 , with the longitudinal axis of the round perpendicular to the length of the ramp. The ramp is then raised so that the round of wood rolls down into the machine, to lie on the cutting floor  23 , between the moving head  16  and the cutting box  24 . 
     The operator then operates the hydraulic controls to move the moving head  16  towards the cutting box  24 . The hydraulic controls are in the form of two spaced levers, both of which have to be moved to the desired position before the hydraulic system operates: this is a health and safety requirement, since it ensures that the operator must use both hands and cannot inadvertently place one hand in a dangerous zone of the machine. 
     Any arrangement of hydraulic controls which meets health and safety requirements (e.g. a lever plus a knob which needs to be depressed) can be substituted for the two lever design. 
     As the moving head  16  moves towards the cutting box  24 , the round of wood lying on the cutting floor  23  is pushed into the knives  25 - 30 . The vertical knives  25 - 29  cut into the face of the wood, and the horizontal knife  30  cuts horizontally through the round of wood to remove any wood which lies above the knife  30 . 
     Although the moving head  16  is connected to the top plate  38  by the connecting arm  37 , movement of the moving head towards the cutting box does not immediately move the top plate  38 : the bracket  36  secured to one side of the moving head and surrounding the adjacent end of the connecting arm  37  is formed with a slot  50  which is dimensioned to receive the bolt  41  on which the adjacent end of the biasing spring  40  is mounted. The slot  50  allows the bracket  36  to move relative to the connecting arm  37  for the first part of the travel of the moving head  16  ( FIG. 6 ). This means that the top plate  38  remains in place over the horizontal knife  30  until the wood pushes the top plate  38  (and thus the arm  37 ) upwards and forwards. From this point, the wood is securely gripped between the moving head  16  and the top plate  38 . 
       FIG. 7  shows the placement of the components at the point at which a piece of wood located on the cutting floor  23  has been contacted by the moving head  16  and has only just come into contact with top plate  38 . 
     As shown in  FIG. 8  continued movement of the moving head  16  towards the cutting box  24  not only forces the lower part of the round of wood through the cutting box but also causes the part of the round of wood which lies above the upper surface of the cutting box to rise up, aided by the bevel on the horizontal knife  30 . If this upward movement is not accommodated, then it can lead to the upper part of the wood placing an upward strain on the connecting arm and additional manual handling of the wood to get the wood back into the cutting box. 
     The present invention overcomes this problem by allowing the top plate  38  to rise up in a vertical plane to accommodate the upward movement of the upper part of the wood: the upward force of the wood on the top plate  38  is accommodated by the upward movement of the top plate which is permitted by the movement of each of the brackets  44  in the corresponding slots formed on the supporting frame  39 . Also, the top plate  38  and supporting frame  39  move horizontally with the connecting arm  37 . This means that, as the lower part of a round of wood is forced through the cutting box by the moving head  16 , the upper part of the round of wood, which lies above the knife  30 , is cut off by the knife  30  but remains securely held between the top plate  38  and the upper part of the plate  35  which forms the front face of the moving head  16 . The movement of the moving head  16  towards the cutting box  24  continues until the knife  30  lies in the groove  35  a formed across the plate  35  ( FIG. 8 ). 
     It is important that the top plate  38  is able to move vertically, because this allows the upper part of the round of wood to ride over the knife  30  as it is cut horizontally, without putting undue strain on that part of the machine, and also minimises the risk of the wood jamming between the knife  30 , connecting arm  37  and frame  39 . 
     Because the lower edge  38   a  of the top plate  38  is beveled to match the bevel on the upper surface of the knife  30 , as the top plate  38  moves vertically and horizontally relative to the knife  30 , the two beveled surfaces i.e. the edge  38   a  of the top plate and the beveled upper edge of the knife  30 , remain in contact, with the edge  38   a  riding smoothly over the beveled edge of the knife  30 . This effectively prevents wood from coming between the top plate and the knife, and thus jamming. 
     Once the cut is complete and the knife  30  lies within the groove  35   a,  the operator reverses the hydraulic ram controlling the moving head  16 , to move the moving head  16  away from the cutting box  24 . During this reverse movement, the uncut portion of the wood remains firmly held between the upper part of the plate  35  and the top plate  38 , because the biasing spring  40  biases the top plate  38  towards the plate  35 . 
     Once the top plate  38  reaches its start position in which the lower edge of the top plate  38  overhangs the knife  30 , the adjacent end of the returning connecting arm  37  has contacted the stop  46 , so that the connecting arm  37  and the top plate  38  to which it is connected cannot move beyond the start position. In this position, any wood gripped between the top plate  38  and the moving head  16  lies over the cutting floor  23 ; continued reverse movement of the moving head  16  releases this wood so that it drops squarely onto the cutting floor  23  for further processing. The above described process is then repeated until the wood has been completely cut up, and then a further round is loaded using the loading ramp  18 . 
     Low friction ultrahigh molecular weight polyethylene (UHMWPE) sheets are mounted between the underside of the moving head  16  and the underlying portion of the chassis, and similar low friction pads are provided between the connecting arm  37  and the bracket  36 ; the use of these pads prevents wear from the friction of steel on steel, without the need for grease or similar lubrication.