The present invention relates to an improved knife holder for a chipper disc or film apparatus for producing chips or flakes from a piece of wood.
It is common to form chips for producing wood pulp for use in the manufacture of paper products, employing apparatus known as chippers a choppers, and to produce flakes or wafers for use in the manufacture of waferboard or oriented strand board, employing similar apparatus known as waferizers and stranders. All of these apparatus employ a disc rotating in the vertical plane and having one or more knives attached to knife holders disposed so that cutting edges thereof extend beyond the face of the disc. A piece of wood is fed against the face of the disc and the knives, so that cuts are made in the wood, producing the chips or flakes. The knives experience, very large forces and must be held firmly in place.
However, the knives must be removable from the knife holder, for reversing a replacing them. It has been a problem to ensure firm attachment of the knives while providing for their easy removal from the knife holders.
As a response, Holmberg et al., US. Pat. No. 4,694,995, proposes a knife holder that includes a filler piece fitting into a recess in the chipper disc, and a cassette for holding the knife. The cassette has a top and bottom part that clamps the knife therebetween and a fastener is inserted through the top and bottom parts that extends into the filler piece but not into the chipper disc. The filler piece is separately fastened to the chipper disc. Though it is as explained in the patent, the filler piece is a relatively large and heavy component, while the top part is relatively small and light. It is proposed that the knife may be removed simply by moving the fastener for the cassette and by lifting the small, light top part, while the larger, heavier filler piece remains fixed to the chipper disc. It is also proposed that the fastener for the cassette may be loosened to remove the knife.
Whether the fastener for the cassette of Holmberg is removed entirely or merely loosened, the top part of the cassette and the knife become loose and at least the top part must be moved to get at the knife. As the knife is heavy and difficult to handle and it is desirable to be able to use two hands for this purpose, the aforementioned requirement imposed by Holmberg is objectionable. Moreover, to the extent that the fastener for the cassette of Holmberg is smaller and lighter, it is capable of exerting less force on the knife than prior art fasteners for knife holders so that the knife is not held as firmly.
Accordingly, them is a need for an improved knife holder for a chipper disc or the like that provides for easier removal of a knife held thereby while providing for more firmly holding the knife during operation of the apparatus.
An improved knife holder for a chipper disc or the like according to the present invention solves the aforementioned problems and meets the aforementioned needs by providing a knife holder for holding a knife having a top and bottom side. The knife holder has a first clamping portion and a second clamping portion for clamping the knife therebetween. One of the clamping portions pivots about a pivot point for clamping the knife, and for releasing the knife, so that it may be easily removed from the knife holder. In the relative position of the firsts and second clamping portions in which the knife is clamped and in their relative positions in which a space is opened up around the knife permitting its removal, the first and second clamping portions are rigidly disposed with respect to one another.
Preferably, the pivoting clamping portion is employed as a lever with the pivot point functioning as a fulcrum for the lever. An applied force applied to the lever is multiplied at the knife to ensure that the knife is firmly held in place with a minimum amount of the applied force.
Therefore, it is a principal object of the present invention to provide a novel and improved knife holder for a chipper disc or the like and method.
It is another object of the present invention to provide such a knife holder and method that provides for increased ease of removing the knife from the knife holder.
It is yet another object of the present invention to provide such a knife holder and method that provides for removing the knife without removing other parts of the knife holder.
It is still another object of the present invention to provide such a knife holder and method that provides for holding the knife with increased firmness and with decreased applied force.
The foregoing and other objects, features and advantages of the present invention will be more readily understood upon consideration of the following detailed description of the invention, taken in conjunction with the following drawings.
A knife holder according to the present invention is particularly adapted for attachment to chipper or waferizer discs and drums for cutting wood chips or flakes from pieces of wood, such as whole logs, lumber and waste wood. The application, however, is not essential to the invention.
Referring to
The top clamping portion 14 is rigidly attached to a base 50 by bolts 40. The top clamping portion is seated on a ledge 26 so as to space the top clamping portion above the base. The bottom clamping portion 16 is disposed in the space provided between the top clamping portion and the base.
Turning to
Pivoting of the bottom clamping portion 16 is driven by a clamping machinists 24. The clamping mechanism is coupled to the top clamping portion 14 so that the clamping mechanism can translate with respect thereto. The clamping mechanism is connected to the bottom clamping portion with a suitable joint for maintaining the connection during translation of the clamping mechanism.
As illustrated in
Preferably, the clamping mechanism 24 is threadingly received in a hole through the top clamping portion 14. An end 28 of the clamping mechanism extends beyond the top clamping portion toward the bottom clamping portion 16. The end 28 has a neck portion 30 that is received in a groove 32 (best seen is
Force applied by the clamping mechanism for pivoting the bottom clamping portion is provided through the end 28. Threading the clamping mechanism so as to move it upwardly or downwardly in the top clamping portion 14 pulls or pushes a driving end 34 of the bottom clamping portion 16 in the same direction.
The bottom surface 20 of the knife 12 is received by a driven end 38 of the bottom clamping portion. In turn, the driven end moves in response to movement of the driving end 34, preferably in the opposite direction as a result of pivoting of the bottom clamping portion 16 about the pivot point 22. The top clamping portion 14 and the bottom clamping portion 16 clamp the knife therebetween in the clamping position of the clamping portions that provides a minimum spacing equal to the thickness dimension of the knife, as shown in FIG. 2. In the clamping position of the clamping portions, the clamping mechanism is threaded into the top clamping portion and is disposed toward the base 50 a maximum amount.
As the clamping mechanism 24 is threaded out of the top clamping portion 14, the clamping mechanism pulls the driving end 34 of the bottom clamping portion 16 away from the base. At a maximum amount of travel of the driving end 34, a maximum space 48 is seated around the knife to permit access thereto for removal or cleaning.
Pinch-off surfaces 52 are provided-on the top and bottom clamping portions that are adapted to meet one another when the top and bottom clamping portions tie spaced the maximum relative amount. The meeting of the surfaces 52 serves two functions. First, in conjunction with the connection of the driving end 34 to the clamping mechanism 24, this immobilizes the bottom clamping portion with respect to the top clamping portion, wedging the second clamping portion between the top clamping portion and the base, i.e., between the pinchoff surfaces and the pivot point 22. This provides the outstanding advantage of allowing the knife to be removed without the need to hold or handle any of the other parts of the knife holder at the same time. A spring-biased plunger mechanism 51 is preferably also provided to ride the bottom clamping portion 16 during its travel and thereby control movement of the bottom clamping portion between the open and clamping relative positions.
A second function of the pinch-off surfaces 32 is that open space 46 that exists behind the knife is cut off from the space 48 for accessing the knife, so that objects within the space 48, such as portions of the upper and lower clamping portions and the knife, can be cleaned without introducing debris into the open space 46, which is generally difficult to clean. For example, the space 48 can be blown with compressed air without forcing debris into the open space 46. The pinch-off surfaces, however, need not provide for both of the aforementioned functions.
Preferably, the bottom clamping portion 16 is configured as a lever for multiplying the force that is applied by the clamping mechanism 24 at the knife, to ensure that the knife 12 is firmly held with a minimum of force. In the geometry or
It is to be recognized that, while a specific knife holder for a chipper disc has been shown and described as preferred, other configurations could be utilized, in addition to configurations already mentioned, without departing from the principles of the invention. For example, while the pivot point 22 and the top clamping portion 14 are sufficiently rigidly disposed with respect to one another to enable the knife 12 to be firmly clamped firmly between the top and bottom clamping portions, this does not preclude some compliance between the pivot point and top clamping portion. Similarly, though the pinch-off surfaces 52 may provide for maintaining the top and bottom clamping portions in substantially fixed relationship to one another in the open position of the clamping members, the pinch-off surfaces may also be suitably compliant. Moreover, though it is preferable to provide that the driven end counterbalances the driving end about the pivot point 22, this is not essential for practice of the invention.
The terms and expressions which have been employed in the foregoing specification are used therein as terms of description and not of limitation, and there is an intention of the use of such terms and expressions of excluding equivalents of the features shown and described or portions thereof, it being recognized that the scope of the invention is defined and limited only by the claims which follow.
Number | Name | Date | Kind |
---|---|---|---|
3542302 | Salzmann, Jr. | Nov 1970 | A |
3572594 | Kershaw | Mar 1971 | A |
3777793 | Miller | Dec 1973 | A |
3981337 | Sundstrom | Sep 1976 | A |
4047670 | Svensson | Sep 1977 | A |
4082127 | Miller | Apr 1978 | A |
4139034 | Chapman | Feb 1979 | A |
4155384 | Svensson | May 1979 | A |
4194545 | Kostermeier | Mar 1980 | A |
4220186 | Sybertz | Sep 1980 | A |
4271882 | Valo | Jun 1981 | A |
4298044 | Hansel et al. | Nov 1981 | A |
4335650 | Prevot | Jun 1982 | A |
4346744 | Beer et al. | Aug 1982 | A |
4423758 | Haller et al. | Jan 1984 | A |
4685497 | Mierau et al. | Aug 1987 | A |
4694995 | Holmberg et al. | Sep 1987 | A |
5271442 | Carpenter et al. | Dec 1993 | A |
5485873 | Crammond | Jan 1996 | A |
5782278 | Larsson | Jul 1998 | A |
5819826 | Schmatjen | Oct 1998 | A |
Number | Date | Country |
---|---|---|
73 35 031 | Dec 1977 | DE |
35 17 236 | Nov 1986 | DE |
PCTUS9927620 | Nov 1999 | WO |
Number | Date | Country | |
---|---|---|---|
Parent | 09705379 | Nov 2000 | US |
Child | 09705379 | US |