Patent Publication Number: US-7712495-B1

Title: Machine for forming a point on wooden stakes

Description:
BACKGROUND OF THE INVENTION 
   The present invention relates generally to a machine for sharpening a point on wooden stakes, and, more particularly, to an apparatus that receives a supply of unsharpened wooden stakes and automatically forms a sharpened point thereon. 
   Wooden stakes are driven into the ground for a plurality of purposes, including fencing support, agricultural crop support, and survey and grade markers in construction. The stakes are formed on a cutting machine that forms the wooden stake in the required dimensions, whereupon the formed wooden blank is then transferred to another machine to form a point at one end to facilitate the driving of the stake into the ground. A number of different machines have been devised to form the sharpened point. Such machines are typically configured to move the wooden stake blank into the path of a cutting or chipping device that cuts away the wood along an angular path to form the customary point. 
   Such machines can be manually operated, as can be seen in U.S. Pat. No. 3,111,971, issued to Elbert Spencer on Nov. 26, 1963, in which a post blank can be inserted into a receiving tube into engagement with an angularly oriented chipping head that cuts away the wooden material at the end of the post to create a point thereon. In U.S. Pat. No. 5,109,896, issued to Christopher Tomes on May 5, 1992, and in U.S. Pat. No. 5,638,877, granted to Norman Apr. on Jun. 17, 1997, the wooden stake blank is manually inserted against a guide fence or tube into engagement with a chipping head to form the sharpened point, wherein the guide fence or tube is positioned at an angular orientation to the chipping head. 
   Wooden posts are also presented to machines to affect the sharpening of an end thereof, as can be seen in U.S. Pat. No. 3,073,362, granted to Simon Bourdon on Jan. 15, 1963, and in U.S. Pat. No. 3,403,710, granted to Richard Garrison on Oct. 1, 1968, in which the wooden post blank is manually presented into a conical chipping head to remove the wooden material at one end of the wooden post blank to form a point thereon. In U.S. Pat. No. 3,451,449, issued to Harold Bouma on Jun. 24, 1969, the wooden post blank is reciprocally moved into engagement with a conical cutterhead at each respective end of the machine to form a point and a cap at the opposite ends of the wooden post. Similarly, the machine disclosed in U.S. Pat. No. 4,387,751, granted to Charles Carter on Jun. 14, 1983, forms a point of wooden pickets by moving the picket blank into engagement with an abrading apparatus to remove the material at the end of the wooden picket blank. 
   The stake point machine disclosed in U.S. Pat. No. 3,190,325, granted to Elmer Mood on Jun. 22, 1965, operates a little differently in that the wooden stake blanks are aligned on a horizontal conveyor and clamped into a fixed position while a shearing head moves vertically into engagement with the wooden stake blank to sever wooden material away from the stake blank to form the point. The shearing head moves in conjunction with a V-shaped striker to affect the shearing of the material away from the stake blank. The conveyor advances sequentially to move the stake blanks into alignment with the striker member to be sheared into a point. 
   Presently commercially available stake pointing machine operate on a reciprocal basis to move a wooden stake blank into engagement with a cutting or chipping apparatus to form the point at the end of the stake. As can be seen in the know prior art references described above, the stakes can be manually handled to affect the sharpening process or in an automated manner in which the stake is clamped or fixed against a support and then moved into engagement with the cutting or chipping apparatus. 
   Such complex reciprocation equipment for the stake requires frames, clamping supports and linear actuators to affect the reciprocal movement of the stakes. It would be desirable to provide a less complex and less expensive stake pointing apparatus for use in industry to provide mass quantities of sharpened wooden stakes in an automated fashion. 
   SUMMARY OF THE INVENTION 
   It is an object of this invention to provide a machine for forming a point on wooden stakes that clamps the wooden stake blank and moves the cutting apparatus into engagement with the clamped wooden stake blank. 
   It is a further object of this invention to provide an effective automated process for sharpening wooden stakes. 
   It is a feature of this invention that the stake pointing machine can perform an automated sharpening of wooden stakes with a minimal number of moving parts. 
   It is as advantage of this invention that the stake sharpening machine can be manufactured at less cost than heretofore known in the industry. 
   It is another feature of this invention that the cutting head operable to form a point on the wooden stake is move into engagement with the wooden stake blank clamped on the support table. 
   It is still another feature of this invention that a walking beam transports the sharpened wooden stakes to a stacking apparatus for removal from the stake sharpening machine. 
   It is yet another feature of this invention that the primary drive apparatus causes a coordinated movement of the clamping apparatus, the movement of the cutting apparatus, and the movement of the conveying apparatus to affect a sharpening of wooden stakes in a sequential manner. 
   It is another advantage of this invention that the cutting apparatus is adjustably mounted on a subframe to permit positional movement thereof to accommodate different sized wooden stake blanks. 
   It is still another advantage of this invention that the cutting apparatus is formed with a conical chipping head that is moved axially into engagement with a wooden stake blank to affect sharpening thereof. 
   It is yet another feature of this invention that the walking beam conveyor sequentially moves the wooden stakes from a supply bin, to the sharpening station and to a remote collection area for stacking and shipping the sharpened wooden stakes. 
   It is still another feature of this invention that a switch engaged by the moving subframe supporting the cutting apparatus automatically trips actuation of a pneumatic or hydraulic cylinder to cause the clamping apparatus to engage the wooded stake blank before being engaged by the cutting apparatus. 
   It is yet another object of this invention to provide a wooden stake sharpening apparatus that is durable in construction, inexpensive of manufacture, carefree of maintenance, facile in assemblage, and simple and effective in use. 
   These and other objects, features and advantages are accomplished according to the instant invention by providing a wooden stake sharpening apparatus in which the conical cutting head is moved linearly along a path into engagement with a clamped wooden stake blank to affect sharpening thereof. A walking beam conveying apparatus moves a wooden stake blank into position from a supply bin where a clamping apparatus holds the stake blank in place while the cutting head moves onto the stake to form a point thereon. The drive mechanism moves the conveyor in coordination with the linear movement of the cutting apparatus, which trips a switch to actuate the clamping mechanism as the cutting head moves toward engagement with the stake blank. The conveyor then moves the sharpened stake toward a collection area while moving another stake blank into position for sharpening as the cutting apparatus is retracted away from the stake, thus providing an automated stake sharpening machine with a minimal number of moving parts. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The foregoing and other objects, features, and advantages of the invention will appear more fully hereinafter from a consideration of the detailed description that follows. It is to be expressly understood, however, that the drawings are for illustrative purposes and are not to be construed as defining the limits of the invention. 
       FIG. 1  is a top plan view of a wooden stake sharpening machine incorporating the principles of the instant invention, the cutting head being moved into a stake engaging position by the drive mechanism; 
       FIG. 2  is a side elevational view of the wooden stake sharpening machine shown in  FIG. 1 , looking at the delivery side of the machine where the sharpened stakes are collected for shipment; 
       FIG. 3  is a side elevational view of the feed side of the wooden stake sharpening machine shown in  FIG. 1 ; 
       FIG. 4  is an end elevational view of the wooden stake sharpening machine shown in  FIG. 1 , looking at the motor for powering the operation of the cutting head; 
       FIG. 5  is an end elevational view of the wooden stake sharpening machine show in  FIG. 1 , but looking at the end of the machine opposite of that depicted in  FIG. 4 ; 
       FIG. 6   a  is a schematic representation of the walking beam conveyor demonstrating the operation of the conveyor; 
       FIG. 6   b  is a schematic representation of the walking beam conveyor depicting the lifting of an object from the base member to move the object up the base member; 
       FIG. 6   c  is a schematic representation of the walking beam conveyor depicting the operation of the conveyor to push an object positioned on the delivery table; 
       FIG. 6   d  is a schematic representation of the walking beam conveyor showing the return of the waling beam to be positioned beneath the positions depicted in  FIG. 6   b;    
       FIG. 7  is a partial end elevational view of the sharpening station and adjacent structure with a wooden stake blank at the bottom of the supply bin ready to be moved to the sharpening station; 
       FIG. 8  is a partial end elevational view of the sharpening station and surrounding structure with the wooden stake blank being moved by the conveyor through the opening in the supply bin to the sharpening station; 
       FIG. 9  is partial end elevational view of the sharpening station and surrounding structure with the wooden stake blank positioned in the sharpening station, the cutterhead having been moved to trip the trip switch for the clamping apparatus so that the clamping member moves into engagement with the wooden stake blank; 
       FIG. 10  is a partial top plan view of the sharpening station and surrounding structure corresponding to the view of  FIG. 9  with the chipping device moving into engagement with the wooden stake blank; 
       FIG. 11  is a partial top plan view of the sharpening station and surrounding structure with the cutterhead moving toward the sharpening station to engage the chipping device with the exposed end of the wooden stake blank; 
       FIG. 12  is a partial top plan view of the sharpening station and surrounding structure with the cutterhead now moving away from the sharpening station and exposing the pointed end of the sharpened stake which remains clamped by the clamping mechanism since the trip switch has not yet been released; 
       FIG. 13  is a partial end elevational view of the sharpening station and surrounding structure with the wooden stake blank being positioned at the sharpening station but disengaged by the clamping apparatus due to the cutterhead moving a sufficient distance to release the trip switch; and 
       FIG. 14  is a partial end elevational view of the sharpening station and surrounding structure with the sharpened wooden stake being moved upwardly to the next saw tooth stop by the conveyor, at which time the next wooden stake blank would be positioned on the sharpening station by the conveyor. 
   

   DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
   Referring to  FIGS. 1-5 , a stake sharpening machine incorporating the principles of the instant invention can best be seen. The stake sharpening machine  10  has a frame  11  supporting a drive mechanism  60 , a cutting apparatus  40 , a supply bin  15 , and a conveyor device  20  for moving the wooden stakes from the supply bin  15  to the delivery table  25  opposite the supply bin  15 . The supply bin  15  is formed by a series of plate members  16  forming an angled wall  17  that feeds wooden stake blanks B, best seen in  FIGS. 7-12 , by gravity to the bottom of a restrictor plate  18  that funnels the wooden stake blanks B to an opening  19  at the bottom of the supply bin  15  that will accommodate a single wooden stake blank B. Preferably, the wooden stake blanks B are stacked along the angled wall  17  in a manner to prevent a congestion of wooden stake blanks B along the restrictor plate  18 , thus permitting a smooth flow of blanks B through the opening  19 , as will be described in greater detail below. 
   The walking beam conveyor  20  is best depicted in  FIGS. 1-6   d . The conveyor  20  is utilized in conjunction with a saw tooth base member  22  that is fixedly secured to the frame  11  of the machine  10 . The saw tooth base member  22  is formed of a plurality of individual saw tooth fins  23  located on the delivery side  12  of the machine  10  to convey sharpened stakes S to the delivery table  25  positioned at the top of the base member  22  to receive the conveyed sharpened stakes S. The conveyor  20  includes a saw tooth conveyor fin  26  corresponding to each of the base member fins  23 , each conveyor fin  26  being formed in a configuration conforming to the base member fins  23  and being positioned adjacent thereto. One skilled in the art will readily recognize that the conveyor fins  26  are mounted in parallel with one another and are moved together as a unit. 
   As is best seen in the schematic diagrams of  FIGS. 6   a  through  6   d , the conveyor fins  26  are mounted for circular motion relative to the base member fins  23 . The drive apparatus for rotating the conveyor fins  26  is represented by the circle  29 . Looking first at  FIG. 6   a , the motion of the conveyor fins  26  is demonstrated by the respective phantom representation of the conveyor fin  26  as the fin  26  moves around the circular arc. At  FIG. 6   b , the movement of the conveyor fins  26  to engage a stake positioned on one of the saw tooth stops  24  on the base member fins  23  is represented by the dashed conveyor fin  31 . The saw tooth configuration of the conveyor fins  26  register with the base member fins  23 . Movement of the drive apparatus  29  pulls the conveyor fins  26  upward and forwardly to the position depicted by the conveyor fin  33  in phantom lines. Since the conveyor fins  26  move upwardly relative to the base member fins  23 , the sharpened stake is lifted accordingly by the conveyor fins  26  above the base member  22 . Further rotation of the drive apparatus  29  moves the conveyor fins  26  forwardly along the arc of movement  29  to the position shown by the conveyor fin  35  in solid lines. 
   The continued rotational movement of the conveyor fins  26  ultimately reaches the position of the fin  37  in phantom lines in  FIG. 6   c . When the conveyor fins  26  pass below the level of the base member  22 , the sharpened stake is deposited back on the base member at the saw tooth stop  24   a , which is the stop located one step higher on the base member fins  23  than the previous stop  24  on which the sharpened stake had been located. Continued rotational movement of the conveyor fins  23 , as demonstrated in  FIG. 6   d , returns the conveyor fins  26  to the position depicted by the conveyor fin  39  in solid lines in  FIG. 6   d  at which point the conveyor fins  26  have been returned to a location immediately below the dashed line position  31  of  FIG. 6   b.    
   Continued rotation of the drive apparatus  29  progresses the sharpened stake up the base member fins  23  one saw tooth stop  24  at a time until the sharpened stake reaches the delivery table  25 . As can be seen in the conveyor fin  37  in phantom in  FIG. 6   c , the sharpened stake that had been positioned at the uppermost saw tooth stop  24   b  would now be deposited on the delivery table  25  when the conveyor fins  26  reach the position  37 . Looking at the advancing of the conveyor fins  26  from the phantom position  33  in  FIG. 6   b  to the solid line position  35  and then to the phantom line position  37 , one skilled in the art will recognize that the sharpened stake, previously deposited on the delivery table  25  on the prior rotational cycle, would be pushed outwardly by the movement of the conveyor fins  26 . Accumulated sharpened stakes on the delivery table  25  can then be handled manually or with separate machine to box or package the stacks in appropriate bundles for shipping to the customer. 
   The cutterhead  40  is formed as a conical chipping device  42  into which a stake blank can be inserted axially to obtain the formation of a point on the end of the stake, not wholly unlike the operation of a conventional pencil sharpened. The conical chipping device  42  is operably connected to a motor  45 , preferably an electric motor that is operable to generate sufficient power to chip wood away from the stake blanks in a rapid manner for efficient production. The cutterhead  40  is reciprocally mounted on linear rails  46  for movement toward and away from the base member  22 . Preferably, the electric motor  45  moves with the chipping device  42  in reciprocating toward and away from the stake blank with wires (not shown) delivering electrical current thereto being mounted in a conventional manner to allow for the reciprocating movement. 
   The position of the rails  46  is selectively movable to affect a precise positioning of the open throat of the chipping device  42 . More particularly, a vertical movement of the rails  46 , and thus the cutterhead  40  can be accomplished through manipulation of the adjustment lever  47  and the accompanying linkage supporting the linear rails  46  and the cutter head  40 . Similarly, the horizontal alignment of the cutterhead  40  can be accomplished through the selective manipulation of the adjustment lever  48 . By appropriate utilization of the position adjustment levers  47 ,  48 , the throat of the chipping device  42  can be properly positioned and repositioned to correspond to differently sized wooden stake blanks so that the throat of the chipping device  42  is properly aligned with the stake blank, irrespective of the dimensions thereof. 
   A clamping apparatus  50  is pivotally mounted next to the reciprocating cutterhead  40  to restrain the wooden stake blank in place on the lowermost saw tooth stops  24   c  on the base member fins  23  while the chipping device  42  is advanced into engagement with the unsharpened end of the stake blanks. The clamping apparatus  50  is formed as a rock shaft  52  rotationally mounted on the frame  11  of the machine  10 . Projecting from the rock shaft  52  toward the cutterhead  40  are a pair of clamp arms  53  that have mounted on the distal ends thereof a length of angle iron forming the clamping member  55  that is movable into engagement with a stake, as will be described in greater detail below. An actuator arm  56  projects from the rock shaft  52  away from the cutterhead  40  for engagement with a linear actuator  57 , such as, preferably, a pneumatic cylinder or a hydraulic cylinder. The stroke of the linear actuator  57  can be varied in known manners to selectively locate the clamping position of the clamping member  45  to correspond to differently sized stakes being sharpened. The linear actuator  57  is operatively powered through an appropriate supply of air under pressure, or to a hydraulic system (not shown) providing hydraulic fluid under pressure to the actuator  57  for operation thereof. 
   A trip switch  59  is position on the adjacent rail  46  for the cutterhead  40  so that any movement of the cutterhead  40  into engagement with the trip switch  59  triggers the actuation of the linear actuator  57  in response to the movement of the cutterhead  40  along the rails  46 . For example, a forward movement of the cutterhead  40  along the slide rails  46  trips the switch  59  to cause an extension of the actuator  57  causing the actuator arm  56  to raise and a corresponding rotation of the rock shaft  52 . This rotational movement of the rock shaft  52 , in turn, causes the clamping arms  53  to move downwardly, driving the clamping member  55  into a clamping engagement of the stake positioned on a support table, which preferably may also be the lowermost saw tooth stop  24   c  on the base members  23 . 
   After sharpening the end of the clamped stake, the cutterhead  40  is reciprocated away from the stake just sharpened, again tripping the switch  59  to cause the linear actuator  57  to contract. This contraction of the linear actuator  57  causes a lowering of the actuator arm  56 , and a resultant raising of the clamping member  55  to release the sharpened stake for movement up the conveyor apparatus  20  as described above. Thus, the clamping of the stake blank to resist the forces asserted on the stake blank by the rotating chipping device  42  is automatically initiated in response to the cutterhead  40  moving toward the stake blank for engagement thereof. 
   The drive mechanism  60  is best seen in  FIGS. 1-3 . The primary drive apparatus is preferably an electric motor  62 , or another appropriate source of rotational power, mounted on the frame  11  of the stake sharpening machine  10 . The electric motor  62  is operatively connected to a gear box  63  to distribute the rotational power provided by the electrical motor  62 . A first output from the gear box  63  (not shown) is operatively connected to the conveyor fins  26  to affect the rotational cyclical motion described above relative to the base member  22  to convey the stake blanks from the bottom of the supply bin  15  to the base member  22  for sharpening, and then upwardly along the base member fins  23  after the stakes have been sharpened, as described in detail above. 
   The second output from the gear box  63  is a crank  65  that rotates at the same rotational speed as the first output rotating the conveyor fins  26 . The crank  65  is connected via a pivoted connecting arm  67  to the cutterhead  40  to cause reciprocal linear movement of the cutterhead  40  along the rails  46  as the crank  65  is rotated by the electric motor  62 . Thus, the reciprocating movement of the cutterhead  40  is timely to the operation of the conveyor fins  26 , as will be described in detail below. The operative power for operating the movable components of the machine  10  are delivered by the electrical motor  45  driving the rotation of the chipping device  42 , the electrical motor  62  driving the cyclical motion of the conveyor  20  and the cutterhead  40 , and the linear actuator  57 , preferably a pneumatic cylinder, driving the operation of the clamping apparatus  50 . As one of ordinary skill in the art will recognize, the stake sharpening machine  10  is constructed in a simple manner with a minimal number of moving parts that will provide an automated process for the sharpening of stake blanks. 
   Looking at all of the drawings, but particularly to the schematic representations in  FIGS. 7-14 , the operation of the machine  10  can best be seen. Wooden stake blanks B are preferably stacked into the supply bin  15  in a manner for efficient engagement at the bottom of the supply bin  15  so that the conveyor find  26  can move the lowermost stake blank B through the opening  19  at the bottom of the supply bin  15 , as can be seen in  FIGS. 7 and 8 . The conveyor fins  26 , with the circular motion described in detail above, deposits the stake blank B on the first saw tooth stop  24  of the base member fins  23 . As the conveyor fins  26  are cycling through the motion shown in  FIG. 6   a , the drive mechanism  60  is pulling the cutterhead  40  toward the stake blank B. Once the conveyor fins  26  have deposited the stake blank B on the lowermost saw tooth stop  24   c , between the positions  35  and  37  depicted in  FIG. 6   c , the crank  65  has moved the cutterhead  40  toward the stake blank B. 
   Continued movement of the drive mechanism  60  pulls the cutterhead  40  along the rails  46  into engagement with the trip switch  59 , which initiates the expansion of the linear actuator  57  and the resultant clamping of the stake blank B against the lowermost saw tooth stop  24   c  on the base member fins  23 , as is depicted in  FIGS. 9 and 10 . At about this point in the cycle, the conveyor fins  26  have pushed any sharpened stakes on the delivery table  25  outwardly to permit the deposit of the next sharpened stake S onto the delivery table  25  at the position  37  shown in  FIG. 6   c . Continued movement of the drive mechanism  60  pulls the chipping device  42  into engagement with the end of the clamped stake blank B, as is depicted in  FIG. 11 , to cause the removal of material therefrom for the formation of the pointed end, as is demonstrated in  FIG. 12 . While the chipping device is preferred to be continually rotating through power delivered by the electric motor  45 , a secondary switch (not shown) could be installed at an appropriate location along the rails  46  to start and stop the rotation of the chipping device  42  so that the chipping device is only rotated while engaged with the stake blank B. While such an operation may saved may save on electrical power, the possible detrimental tradeoff may be the increased wear and tear on the electric motor  45  and the chipping device  42 . 
   As the drive mechanism  60  cycles the conveyor fins  26  through the lower part of the drive cycle from the position  37  through to the position  39  and then position  31 , the crank  65  pulls the chipping device  42  into engagement with the stake blank B and then away from the now sharpened stake S, as is shown in  FIG. 12 . As the cutterhead  40  passes the trip switch  59  on the return trip away from the sharpened stake S, the clamping mechanism  50  is disengaged, as is reflected in  FIG. 13 , to allow the conveyor fins  26  to engage the sharpened stake S at position  31  and lift the sharpened stake onto the next saw tooth stop  24 , which is shown in  FIG. 14 . As the newly sharpened stake S is being moved onto the next saw tooth stop  24 , a new stake blank B is being moved from the bottom of the supply bin  15  and deposited onto the lowermost saw tooth stop  24   c  as described above. 
   The cycle is repeated with each revolution of the drive mechanism  60 , moving each sharpened stake S upwardly along the base member fins  23  until reaching the delivery table  25  where the sharpened stakes can be collected for shipment or further handled by stacking and packaging machinery (not shown). At full capacity, the machine  10  is capable of sharpening up many stake blanks per hour, while providing an automated process that requires only a single operator to load stake blanks into the supply bin  15  and to remove sharpened stakes from the delivery table  25 . 
   The invention of this application has been described above both generically and with regard to specific embodiments. Although the invention has been set forth in what is believed to be the preferred embodiments, a wide variety of alternatives known to those of skill in the art can be selected within the generic disclosure. The invention is not otherwise limited, except for the recitation of the claims set forth below.