System of chipper knives and knife stops

Patent metadata

Field	Value
Publication number	US-11141877-B2
Application number	US-201916583563-A
Country	US
Kind code	B2
Filing date	Sep 26, 2019
Priority date	May 8, 2019
Publication date	Oct 12, 2021
Grant date	Oct 12, 2021

Abstract

A disc chipper has thick double-edged chipper blades clamped in rectangular pockets between a knife segment and a knife clamp which are connected to a chipper disc. The blades are precisely positioned for cutting by knife stops selected from a set of knife stops of incremental modular widths. A different width knife stop is used to position the chipper knife blades each time it is sharpened. After each sharpening the knife blade has a selected width which is smaller by a constant incremental value, and it is assembled with a mating knife stop from the set so that the blade edge position remains unchanged.

First claim

I claim:

1. A disc chipper comprising:
a chipper disc;
a plurality of cutting assemblies fixed to the chipper disc, wherein each cutting assembly comprises:
a knife segment mounted to the chipper disk, the knife segment having portions defining a first chipper knife engaging surface which faces the chipper disc;
a chipper knife having cutting edges on opposed sides, the cutting edges being defined by inclined edge planes which extend between parallel top and bottom surfaces of the chipper knife;
a knife clamp having a second chipper knife engaging surface, the knife clamp being mounted to elastically bias the knife clamp toward the chipper disk, and having at least one second adjustable mechanism to bias the knife clamp away from the chipper disk to clamp the chipper knife between the knife segment first chipper knife engaging surface and the knife clamp second chipper knife engaging surface;
a back surface fixed with respect to the knife segment, the knife clamp or the chipper disk and together with the first chipper knife engaging surface and the second chipper knife engaging surface to define a pocket;
a knife stop mounted within the pocket and engaging the back surface, the knife stop having an inclined surface which supportively engages one of the inclined edge planes of the chipper knife within the pocket; and
wherein the knife stop has portions defining a hole opening on the inclined surface for receiving an extraction tool.

2. The disc chipper of claim 1 wherein the knife stop portions defining a hole further define an inner threaded portion for receiving and engaging with threads on the extraction tool.

3. The disc chipper of claim 1 wherein the knife segment is bolted to the chipper disc, and wherein there are a plurality of first bolts arranged to elastically bias the knife clamp toward the chipper disk and a plurality of second bolts arranged to bias the knife clamp away from the chipper disk to clamp the chipper knife between the knife segment first chipper knife engaging surface and the knife clamp second chipper knife engaging surface.

4. The disc chipper of claim 1 wherein each of the plurality of cutting assemblies further comprises:
portions of the knife clamp defining a groove which extends below the second knife engaging surface;
a counter knife positioned in the groove, the counter knife having an upper surface which engages the bottom surface of the chipper knife and extends along the bottom surface of the chipper knife and protrudes beyond the knife clamp to prevent wear of the knife clamp;
portions of the knife clamp which define a plurality of counter bores; and
a plurality of magnets, one mounted in each of the knife clamp counter bores such that the magnets at least partially engage the counter knife to hold the counter knife to the knife clamp.

5. A system of chipper knives and knife stops for use in a disc chipper used to chip wood logs for the production of wood fiber containing pulp; the system comprising:
a plurality of chipper knives, each chipper knife having a length, a width, and a thickness, wherein each chipper knife has an upper surface and a parallel lower surface, and along the length of the chipper knives at least one cutting edge plane extends from the upper surface to the lower surface to define a first cutting edge spaced in a width direction from a second engagement edge, the distance in the width direction between the first cutting edge and the second engagement edge defining the width of the chipper knife, and wherein each chipper knife of the plurality of chipper knives is releasably associated with the same chipper disc and extending within one of a plurality of pockets and positioned by a knife stop engaged against a back surface, said knife stop being one of a set of knife stops;
for each of the plurality of chipper knives, the set of knife stops comprises: a series of knife stops, in which a first knife stop is narrower in the width direction than a second knife stop, which is narrower in the width direction than a third knife stop, and each member of the series of knife stops is narrower than the subsequent member; and
such that all the first knife stops of all the sets of knife stops for all the chipper knives are of the same width, and the subsequent knife stops of all the sets are wider than the previous knife stops; such that as the plurality of chipper knives are repeatedly removed from their pockets and sharpened to a common and narrower width, the chipper knives may be returned to their association with the chipper disc, and the combined width of each sharpened chipper knife in combination with one of the subsequent knife stops remains the same, so the plurality of chipper knives are similarly positioned in the disc chipper.

6. The system of chipper knives and knife stops of claim 5 wherein each chipper knife second engagement edge forms a second cutting edge which extends from the upper surface to the lower surface.

7. The system of chipper knives and knife stops of claim 5 wherein within each set of knife stops, the difference in width between the first knife stop and the second knife stop is the same as the difference in width between the second knife stop and the third knife stop.

8. The system of chipper knives and knife stops of claim 6 wherein each knife stop of the sets of knife stops has an inclined surface which is positionable to engage one of the plurality of chipper knives, and wherein each knife stop has portions adjoining said inclined surface which define an engagement for an extraction tool.

9. The system of chipper knives and knife stops of claim 8 wherein the portions adjoining said inclined surface define a hole opening on the inclined surface for receiving the extraction tool.

10. The system of chipper knives and knife stops of claim 9 wherein the knife stop portions defining a hole further define an inner threaded portion for receiving and engaging with threads on the extraction tool.

11. A method of sharpening and using a plurality of chipper knives in a disc chipper, wherein each chipper knife has a first cutting edge spaced in a width direction from a second engagement edge, the method comprising the steps of:
securing the plurality of chipper knives to a chipper disc, such that each chipper knife is engaged against a first knife stop of a first width in the width direction, wherein a combined width in the width direction of each combination of chipper knife and first stop is a first measure, and the first cutting edges are disposed to engage incoming wood logs;
using the plurality of chipper knives in the disc chipper to chip wood logs until the plurality of chipper knife first cutting edges become dull;
removing the plurality of chipper knives from the chipper disc;
sharpening the chipper knife first cutting edges, thereby decreasing the widths of the chipper knives;
removing the first knife stops and replacing them with second knife stops of a second width which is greater than the first width;
replacing the plurality of sharpened chipper knives to engage against the second knife stops and securing them to the chipper disc, wherein the combined width of the each replaced sharpened chipper knife and its engaged second knife stop is said first measure; and
using the plurality of chipper knives in the disc chipper to chip wood logs.

12. The system of chipper knives and knife stops of claim 11 wherein the second engagement edge forms a second cutting edge.

13. The method of claim 12 wherein before the step of sharpening the chipper knife first cutting edges, further comprising the steps of:
replacing the chipper knives in engagement with the first

Assignees

• Valmet Technologies Inc

Inventors

• Peck Derrel M

Classifications

• B27L11/02

  of wood shavings or the like · CPC title

• B27L11/005 Primary

  Tools therefor · CPC title

• B27G13/04

  Securing the cutters by mechanical clamping means · CPC title

• B27G13/10

  Securing the cutters, e.g. by clamping collars · CPC title

• B02C18/184

  with peripherally arranged demountable cutting tips or elements · CPC title