Tree girdling with a water jet cutting device

Abstract

A tree girdling technique that uses a water jet cutting device to effect girdling of a tree. After making an undercut in a tree, a girdler is wrapped about a tree at an elevation lower than the undercut and pressurized water with abrasive particles are dispensed from the girdler about the girth of the tree. The dispensing may be done either by rotating a port about the girth or by positioning a series of ports each arranged to direct the pressurized water with abrasive particles to flow in a stream at an oblique angle relative to the inner face of the girdler.

Description

CROSS-REFERENCE TO CO-PENDING PATENT APPLICATIONS

[0001] Priority is claimed from provisional application serial No. 60/376,294, filed Apr. 26, 2002.

BACKGROUND OF THE INVENTION

[0002] 1. Field of the Invention

[0003] The present invention relates to cutting around the girth of a tree with a water jet cutter that is moved around the tree by an annular guide.

[0004] 2. Description of Related Art

[0005] As recognized by U.S. Pat. No. 3,971,422, conventional practice in tree felling includes the cutting of an undercut or face cut in a tree trunk transversely to the intended lay of the felled tree. Typically, the face cut removes a tree trunk section having a rounded surface with two planar cut surfaces. The undercut extends somewhat less than half way through the tree trunk. A second cut, termed a back cut, is made inwardly from the opposite side of the tree and extends inwardly anywhere from one-half to two-thirds of the trunk diameter, terminating in close proximity to the undercut at the time the fall commences.

[0006] As recognized by U.S. Pat. No. 4,996,773 tree girdling is a process that involves cutting a horizontal strip through the tree bark through the Cambian layer around the entire circumference of the tree to interrupt the flow of water and nutrients. This process usually results in the death of the tree.

[0007] The cutting tool used for girdling should be adjusted so that the cambium layer of the tree is completely severed to prevent translocation of water and other nutrients. If the cut is too shallow, then the cambium layer may be not completely severed, which may allow the tree tissue to regenerate. If the cut is too deep, then tree may become unstable and prone to topple when subjected to high winds. Trees which are blown down in this fashion often cause damage to surrounding tree species.

[0008] Hand held power cutting tools have proved to be unsatisfactory in cutting or girdling trees. A particularly hazardous drawback of hand held cutting tools that utilize a rotating cutting edge (such as chainsaws) is the tendency for the cutting tool to “kickback” when jammed. The rotating part of the cutting tool, such as the chain of a chainsaw, when stopped or impaired, causes an upward force on the tool. This can be extremely dangerous to the user as the rotating chain or other cutting portion can be forced upwards and back to pivot towards the user and can seriously cut the user. The pivot point is generally the wrist of the hand of the user holding the cutting tool which is the weakest point between the user and the tool. The wrist is generally controlled by relatively weak muscle groups which are unable to properly control or prevent “kickback”.

[0009] Manually driven tree girdling tools also suffer from significant shortcomings. Such tools have been unable to achieve a deep enough cut and have resulted in tremendous worker fatigue because of their poor leverage design. Other hand-held tree girdlers have proven to be ineffective since they require too much work area around each tree to operate the tool effectively, thus rendering the tool ineffective in dense forest.

[0010] The present inventor observed that the most dangerous part of felling or chopping down the tree is not during the formation of the undercut or face cut in a tree trunk transversely to the intended lay of the felled tree, but rather during girdling. Tree girdling or cutting about the girth of the tree may last hours depending upon the tree girth dimension. The kickback of the chainsaw that forces the rotating chain toward the user may seriously injure the user.

[0011] It would therefore be desirable to change the tools and techniques that are used to fell trees so as to avoid the risk of injury to those who are engaged in cutting down trees.

SUMMARY OF THE INVENTION

[0012] One aspect of the invention resides in girdling a tree by cutting the girth with a water jet of abrasive particles, instead of using a chainsaw. A compressor supplies pressurized water that is mixed with abrasive particles to pass through a hose leading to the tree whose girth is to be cut. The terminal end may be secured to a port of jaws that are closed about the girth of the tree to be cut. The terminal end may be moved in a circumferential direction about the tree. Alternatively, a plurality of terminal ends of either different hoses or different branches from the same hose are secured to associated ports in the jaws about the entire girth of the tree. Pressurized water with abrasive particles passes through each of the hoses either simultaneously or successively to cut the entire girth. The direction of the cut is at the same oblique angle to the face of the tree being cut at each of the ports. As the cutting progresses, the terminal ends may be moved in a radial direction to shrink the size of the gap that the flow must travel before impacting the tree girth.

BRIEF DESCRIPTION OF THE DRAWING

[0013] For a better understanding of the present invention, reference is made to the following description and accompanying drawings, while the scope of the invention is set forth in the appended claims:

[0014] FIG. 1 is a perspective view of a tree and a schematic representation of the present invention in place to cut about a perimeter of the tree.

[0015] FIG. 2 is a perspective view of an enlargement of a portion of FIG. 1 that shows a belt. legs and a guide rail.

[0016] FIG. 2A is a schematic representation of the belt of FIG. 2.

[0017] FIG. 2B is a schematic representation of legs of FIG. 2.

[0018] FIG. 2C is a schematic representation of a guide rail of FIG. 2.

[0019] FIG. 3 is a schematic representation of a rolling cart with a supporting arm and jaws in accordance with a further embodiment.

[0020] FIG. 4 is a partial view of the belt in accordance with the further embodiment.

DETAILED DESCRIPTION OF THE INVENTION

[0021] Turning to the drawing, a tree trunk 10 is felled by first making an angled undercut 12 using conventional techniques. For instance, a chainsaw may be used. Thereafter, a perimeter cut 14 is made about a perimeter or girth of the tree trunk 10 at an elevation below the angled undercut 12 by employing a cutting device that uses a water jet to effect the cutting with pressurized water and abrasive particles.

[0022] In accordance with one embodiment, a belt 20 is used to hold a terminal end of the cutting device. The belt 20 is moved about the circumference of the tree trunk and thus the terminal end of the cutting device is likewise moved with the belt. Such movement is done by connecting the belt 20 to collapsible legs 22 that have wheels 24 on a guide rail 26 running about the tree trunk on the ground that forms a loop encircling the tree trunk. A hose 28 delivers the pressurized water with abrasive particles through a belt port 60 to cut the tree. A compressor 30 supplies the pressurized water.

[0023] A terminal end of the hose 28 is secured to the belt port 60 with any conventional technique for securing a hose to an opening. The abrasive particles may be sand or metallic filings or fragments.

[0024] As best seen in FIG. 1, the compressor 30 is preferably spaced far enough away from the tree so that when the tree topples, the tree will not fall on the compressor 30. The same compressor 30 may be used to supply a flow of pressurized water with abrasive particles to multiple water jets via multiple hoses by supplying the flow either simultaneously to each of the hoses or in a successive manner to each. Any conventional cutting device that supplies pressurized water with abrasive particles that cuts wood may be used. If the pressure available from the compressor is too low to enable cutting simultaneously from each of the hoses, then the cutting needs to be done by sending the pressurized water with abrasive particles to the hoses in succession so that the pressure level delivered is sufficient for wood cutting.

[0025] The belt 20 may have an external face (facing outwardly) made of made of a metal alloy and an inner face (facing inwardly) made of a ceramic cushion. The belt consists of a plurality of segments 32 connected to each other in succession by hinge pins 34. This allows the belt 20 to be better fitted about the girth of the tree by allowing adjustment of the belt. Leg hooks 36 are provided at spaced intervals on each section to connect with respective ones of legs 22.

[0026] Each leg 22 has an upper part 40 and a lower part 42 and a kneecap 44 between the upper and lower parts. The kneecap 44 is pivotally connected to the upper part 40. The kneecap 44 is configured to maintain the upper part 40 in a position suited for making the perimeter cut with the terminal end of the hose 28 as long as the perimeter cut has not been completed. Once the perimeter cut is done, however, the kneecap 44 releases the upper part 40 so as to allow the upper part 40 to pivot about the kneecap 44 and fall downwardly closer to the guide rail 26.

[0027] The lower part 42 is not foldable and supports the wheels 24, which are double wheels that run on the guide rail 26. The automatic folding of the upper part 40 is done to move the belt 20 away from the tree severing area just in case the stump of the cut tree falls in the vicinity of where the belt was located during the cutting operation.

[0028] The automatic folding may be triggered in any of a variety of different techniques. Sensors may be used to detect when the pressurized water with abrasive particles that emerges from the terminal end of the hose 28 clears the perimeter cut already made so as to indicate that the perimeter cut is complete. Such sensors may send signals back to the compressor 30 to stop sending pressurized water with the abrasive particles through the hose 28. Such signals may also be used to trigger the kneecap 44 to release the upper part 40 from its position so as to allow the upper part 40 to fall.

[0029] Alternatively, the kneecap 44 itself may be powered by diverting the pressurized water (preferably without the abrasive particles) to it so that when the pressurized water is present, the kneecap 44 is operative. The kneecap 44 may be operative either hydraulically from the pressurized water or by a motor, to maintain the upper part 40 in the proper position for the water jet terminal end or cutting head to effect the perimeter cut.

[0030] Once the pressurized water fails to be diverted to the kneecap 44, as would be the case when the compressor 30 stops sending pressurized water, the upper part 40 falls. That is, the absence of such pressurized water causes the kneecap 44 to no longer maintain the upper part 40 in the proper position, allowing the upper part 40 to fall either by its own weight or under a spring bias (if springs are provided). Indeed, a separate locking mechanism may be provided to lock the kneecap 44 is place when pressurized water is present and to release the kneecap when no pressurized water is present (either at the kneecap or emerging from the terminal end or cutting head of the water jet cutting device).

[0031] The guide rail 26 is anchored to the soil with metallic claws 50 on either side of the double track. The metallic claws 50 are held in place beneath metallic U profiles 52, which are also metallic such as made from steel bar. A pair of metallic claws 50, one on the inner side of the guide rail 26 and the other on the outer side of the guide rail 26, are connected to each other with a link 54. The link is preferably metallic such as made from steel bar.

[0032] A hydraulic drive may be used to turn axles of one or more of the wheels 24 to drive the belt and therefore move the water jet cutting device discharge around the girth of the tree. The hydraulic drive is driven by the pressurized water from the compressor 30 used to power the water jet. The water jet is connected to the belt at a port 60 and the weight of the device may rest on the ground.

[0033] As compared with conventional tree girdling techniques using chainsaws, the time spent by a labor force in cutting down multiple trees can be significantly lowered by using the belt and water jet cutting device of the present invention. Each tree would have its own guide in place about the tree trunk to support the discharge of the associated water jet cutting device. Thus, the only time spent by the labor force involves forming the undercut and then setting up the belt into its position about the girth of the tree trunk and connecting the associated water jet. When done, the labor force can turn its attention to the next tree to be cut, while activating the water jet to cut the tree girth from a safe distance.

[0034] The setup is as follows. The guide rail 26 is placed on the ground to encircle the tree trunk to form a loop. The guide rail 26 is secured into the ground with metallic claws 50. The belt 20 is wrapped about the girth of the tree by adding belt sections 32 as necessary to complete circumference of the girth. The legs 22 are secured to the leg hooks 36 and to wheels 24. The guide rail 26 engages with the wheels 24. The terminal end of the hose 28 is connected to the belt port 60 so that when the pressurized water with abrasive particles emerges through the belt port 60, it flows at an angle that is oblique to the inner face of the belt 20. The hose 28 of the compressor 30 is attached to the terminal end or cutting head of the water jet.

[0035] The water supply for the compressor 30 may be any water source, which should be readily available in a forest area such as a stream or river. The water may need to be purified, which may be done with conventional filtering equipment. During the course of operating of the water jet cutting device, the pressurized water emerging may miss the trunk of the tree and strike the inner face of the belt 20. For this reason, the inner face of the belt 20 is made of a ceramic material that is more resistance to the impact of the pressurized water striking it than is the case for the metal alloy. Such an arrangement extends the life of the belt 20.

[0036] As an alternative, the belt 20 may be replaced by two belt segments 32. The first belt segment holds the hose 28 and the second belt segment is arranged to be in the path of were the water jet may strike if it clears the cutting area of the tree. The two belt segments may be connected to-each other by wire or by any suitable link.

[0037] Turning to FIGS. 3 and 4, a further embodiment is shown that does away with the need for guide rails 26. Instead, a rolling cart 70 is used that supports an arm 72 from which extend two jaws 74. All necessary wires, pipes or hose 28 run through the arm 72. The jaws 74 have lateral openings 76 for receiving links of the belt 20 or belt segments 38 to firmly hold them in place. Each of the belt segments 38 may carry its own belt port 60 that is fitted with its own terminal end of a branch of the hose 28.

[0038] The jaws 74 are pivotally joined together at the end of the arm 72 and move swing about the pivot towards or away from each other. Each jaw may be curved because of pivots 34 to facilitate being wrapped around a portion of the girth of a tree trunk, that is, each jaw may conform in shape to a curvature of the girth of the tree. The belt segments 38 that make up the jaws, however, may each remain flat without curvature because the pivot 34 between them adapts to the curvature of the girth of the tree, particularly where the widthwise dimension of the belt segments 38 is small.

[0039] Pressurized water with abrasive particles may reach multiple belt ports 60 by employing a manifold to distribute the flow to each of the belt ports 60. The manifold has hose segments that branch off to connect with each of the belt ports 60. Each of the belt ports angles the cutting head of end of the water jet cutting device preferably upwardly at an oblique angle so that cut material is forced laterally without being blocked by the belt. To provide some rigidity to the jaws where the belt segments 38 are to some extent flexible, metal alloy links 62 are provided on the opposite side of the belt segments 38 from which is attached the pivots 34. Thus, the metal alloy links 62 form an inner facing surface of the jaws and may provide a substantially flat surface.

[0040] As an alternative to the use of a manifold, separate hoses 28 may be used. In either case, the pressurized water with abrasive particles is sent to each hose or hose segment, as the case may be, either simultaneously if sufficient water pressure is available or in succession. If done in succession, the flow to each hose or hose segments is either open or closed at any given time by valves (not shown). Such valves are controlled to open or close in response to instructions from the controller.

[0041] Each terminal end of the hose 28 may be movable relative to the cut portion of the tree so that it may be moved closer to the center of the tree. Such movement is useful to avoid dissipation of the pressurized water as it travels toward the tree after emerging from the hose. Detectors or a time clock may be used to trigger movement of the hose after cutting has commenced.

[0042] For instance, if based on the species of tree being cut and its diameter, the amount of time needed to cut the tree by a proper amount for effective girdling may have been observed, measured or computed previously and the same time duration may be applied again. After the elapsed time has passed, it is likely that an appropriate amount of cutting has occurred.

[0043] Alternatively, as the gap widens between the terminal end of the hose and the tree trunk, the pressurized water with abrasive particles will have further to travel to reach wood to effect cutting. If the distance is too great, the impact felt by the tree trunk from such pressurized water with abrasive particles reduces due to dispersion. Such lessened impact effects may be detected with sensors, which are arranged to transmit appropriate signals to a controller [not shown]. In response to the signals signifying that the distance is too great, the controller sends instruction signals to a driver to drive the terminal ends of the hoses or hose segments closer in a radial direction to the center of the tree trunk.

[0044] The movement of each terminal end of the hose 28 may be carried out by a driver of any conventional technique, such as with a motor or hydraulic drive. Such drivers may operate in response to instructions from a controller.

[0045] The controller determines whether there is a need to move the terminal end of the hose 28 based on signals from the sensors and, if such a determination is affirmative, instructs the driver to move the terminal end of the hose 28 inwardly and the sensing continues. If negative, no movement instructions are sent. Both the driver and the controller are powered from electricity supplied through the wires in the arm 72 and/or by hydraulic pressure supplied through pipes in the arm 72.

[0046] For the sake of convenience, the belt 20 or jaws 74 that wrap around the girth of the tree will be referred to as a girdler. Also, the hose 28 or hoses may be considered a tubular structure. While the foregoing description and drawings represent the preferred embodiments of he present invention, it will be understood that various changes and modifications may be made without departing from the spirit and scope of the present invention.

Claims

1. A tree girdling apparatus, comprising:

a girdler having at least one port and an inner face;

a source of pressurized water with abrasive particles; and

a tubular structure that conveys the pressurized water with abrasive particles from the source to the at least one port and arranged to direct the pressurized water with abrasive particles to emerge in a stream from the at least one port at an oblique angle relative to the inner face of the girdler.

2. An apparatus as in claim 1, wherein the girdler includes two jaws movable between an open position and a closed position, the two jaws configured and arranged to be moved toward each other to reach the closed position and to be moved away from each other to reach the open position, the jaws carrying the port.

3. An apparatus as in claim 1, further comprising:

a rail forming a loop;

wheels on the rail so as to allow the wheels to move along the rail in response to forces being exerted; and

legs connecting the wheels with the belt for moving the girdler about the loop.

4. An apparatus as in claim 2, further comprising at least one locking device responsive to delivery of the pressurized water to maintain the girdler at a elevation in the closed position and being responsive to cessation of delivery of the pressurized water to free the girdler to enter into the open position.

5. An apparatus as in claim 1, wherein the girdler has a curvature, the at least one port being a plurality of ports, the tubular structure including a plurality of hoses each being connected to associated ones of the ports, each of the hoses being arranged to convey the pressurized water with abrasive particles from the source to associated ones of the ports.

6. An apparatus as in claim 1, further comprising a compressor as the source of the pressurized water.

7. An apparatus as in claim 1, wherein the inner face of the girdler is a ceramic cushion.

8. An apparatus as in claim 1, further comprising an arm that supports the girdler.

9. An apparatus as in claim 1, wherein the inner face of the girdler is configured to conform substantially to a curvature of the girth of the tree.

10. A method of tree girdling, comprising:

arranging a girdler about a girth of a tree, the girdler having at least one port and having an inner face; and

conveying water with abrasive particles from a source via a tubular structure to at least one port so that the water with abrasive particles emerges in a stream from the at least one port at an angle that is oblique to the inner face of the girdler.

11. A method as in claim 10, further comprising moving the girdler along a rail, the rail forming a loop.

12. A method as in claim 10, further comprising driving the girdler on the rail in response to delivery of the pressurized water.

13. A method as in claim 10, wherein the girdler includes two jaws, further comprising moving the two jaws from an open position to a closed position about the girth of the tree by moving the two jaws toward each other.

14. A method as in claim 10, further comprising maintaining the girdler at a elevation in response to delivery of the pressurized water and freeing the jaws to move to the open position from the closed position in response to cessation of delivery of the pressurized water.

15. A method as in claim 10, wherein the arranging includes hinging a plurality of sections of the girdler to each other to form a ring, engaging wheels on the rail and extending legs between the wheels and the girdler.

16. A method as in claim 10, further comprising arranging a compressor to provide the pressurized water, and extending a hose between the compressor and the girdler to convey the pressurized water.

17. A method as in claim 10, further comprising cushioning the girdler with a ceramic cushion on an inside face of the girdler.

18. A method as in claim 10, further comprising supporting the girdler with an arm.

19. A method as in claim 10, further comprsing substantially conforming the inner face of the girdler is configured to a curvature of the girth of the tree.