WO1992013685A1

WO1992013685A1 - Canter

Info

Publication number: WO1992013685A1
Application number: PCT/SE1992/000063
Authority: WO
Inventors: Kenneth Larsson
Original assignee: Hardmetallservice I Mockfjard AB
Current assignee: Hardmetallservice I Mockfjard AB
Priority date: 1991-02-05
Filing date: 1992-02-04
Publication date: 1992-08-20
Anticipated expiration: 1993-08-05
Also published as: SE467915B; AU1270992A; SE9100345D0; SE9100345L

Abstract

A canter for processing a log by directly cutting into chips the material removed from the log, comprises a rotatable canter member which essentially has the shape of a truncated cone and on whose circumferential surface are provided replaceable processing means (4, 4') for cutting away material from the log. These processing means have a cutting edge structure which is composed of two substantially straight cutting edges (22, 22') at an angle to one another. According to the invention, the cutting edge structure (22, 22') is composed of at least two separate, flat processing means (4, 4') in the form of indexable inserts each having at least two separate, straight cutting edges (22, 22'). The processing means are so angled to one another that at first cutting edge (22) extends substantially radially perpendicular to the axis of rotation of the canter member, whereas a second cutting edge (22') extends at an angle to the first cutting edge, preferably in parallel with the circumferential surface of the cone.

Description

CANTER

The present invention relates to a canter for pro¬ cessing a log by directly cutting into chips the material removed from the log, said canter comprising a rotatable canter member which essentially has the shape of a trun¬ cated cone and on whose circumferential surface are pro¬ vided replaceable processing means for cutting away mate¬ rial from the log, said processing means having a cutting edge structure which is composed of two substantially straight cutting edges at an angle to one another. Background of the Invention

Canters of this type are used in the sawmill industry for processing at least one side of a round log before or during sawing. Usually, two canters are positioned oppo¬ site to one another so as to shape the round log longitu¬ dinally fed therebetween into a cant having two parallel, flat lateral surfaces. The thus-obtained flat surface is comparatively rough, and usually there is provided a second canter member or fine-canter at the narrow end of the cone in order to finish the log surface.

In such canters, all or most of the material removed from the log in the shaping of the cant should be directly cut into chips without previous sawing, and the resulting chips should have such a size and shape that they lend themselves to the application aimed at, e.g. as raw πate- rial in the production of pulp. To enable cutting into a given size and shape, the processing means or cutting knives are designed as above, i.e. with a cutting edge structure composed of two substantially straight cutting edges at an angle to one another. A first cutting edge extends substantially radially perpendicular to the axis of rotation of the canter, and serves to split the wood. A second cutting edge extends from the end of the first cutting edge furthest away from the axis of rotation, rearwards from the narrow end of the cone and essentially in parallel with the circumferential surface of the cone. The second cutting edge serves to cut the wood transverse¬ ly of the longitudinal direction of the fibres. With such a cutting knife, the size and shape of the chips can be varied by controlling the feeding rate of the log, the rotational speed of the canter, the size of the cutting knives, and/or the number of cutting knives employed in the canter.

The cutting knives hitherto used are made in one piece and are very expensive because of their complicated design. They should therefore be regrindable to permit extended reuse. They should also be displaceable rela¬ tive to the canter, or a holder fixed thereto, to enable adjustment of the cutting edge structure to the correct position, despite the cutting knives showing various degrees of wear. Each knife is mounted on a cylindrical holder which is fitted into and welded in a hole formed in the circumferential surface of the canter. The cutting knife projects a distance outwardly of the canter through a slot in the holder, and is fixed to the inside of the holder by a bolt through an elongate groove in the rear part of the knife. The cut chips are removed through the conical circumferential surface of the canter, more pre¬ cisely through the slot through which the knives project. As a result of the inclination and the geometrical design of the knives, the free passage through the slot is com¬ paratively small, preventing the chips from passing through the slot and causing them to be thrown out at the front of the canter. In addition, the fastening bolt should be protected from the chips removed through the slot by a chip-guiding means before the bolt, which fur¬ ther obstructs the passage of the chips.

Replacing the cutting knives, for regrinding or some other purpose, is an extremely time-consuming and laborious operation which necessitates mounting and set- ting each and everyone of the cutting knives. In practice, one person has to go into the cone from the rear, and loosen and tighten the bolts retaining the cutting knives, while someone else is standing at the front of the canter to check the positions of the cutting edges relative to the circumferential surface. Bearing in mind that an ordi¬ nary canter has about 120 cutting knives, it will be appreciated that the mounting procedure is extremely time- consuming and costly. Objects of the Invention

One object of the present invention is to provide a canter which greatly facilitates dismounting and remount- ing of the processing means and which obviates the need of positional adjustment of these means, thereby saving a lot of time and eliminating the risk of misadjustment. Another object is to enable the use of small and simple processing means in the form of indexable inserts which are so inex- pensive that they can be thrown away when worn. Yet an¬ other object of the invention is to provide a holder for the processing means, which is readily adjustable into different projecting positions relative to the circumfe¬ rential surface of the canter and provides more space for the chips passing through the canter. Summary of the Invention

According to the invention, these and other objects are achieved in that the cutting edge structure is com¬ posed of at least two separate, flat processing means in the form of indexable inserts each having at least two separate, straight cutting edges, said processing means being so angled to one another that a first cutting edge extends substantially radially perpendicular to the axis of rotation of the canter member, whereas a second cutting edge extends at an angle to said first cutting edge, pre¬ ferably in parallel with the circumferential surface of the cone.

Brief Description of the Drawings In the accompanying drawings, FIG. 1 is a section of a pair of canters according to the invention, FIG. 2 is a plan view of a canter, FIG. 3 is a front view of a first embodiment of a holder with processing means, FIG. 4 is a top view of the holder in Fig. 3, FIG. 5 is a side view of the holder in Figs 3 and 4, FIG. 6 is a front view of a second embodiment of a holder with processing means, and FIG. 7 is a top view of the holder in Fig. 6. Description of the Preferred Embodiments

Fig. 1 is a section of a canter 1 according to the invention. A first canter member or rough-canter is desig¬ nated 2, and a second canter member or fine-canter is designated 3. The rough-canter 2 essentially has the shape of a truncated cone 2' on the circumferential surface of which are provided processing means or cutting knives 4. The canter 1 is rotatable about a shaft 5 which is mounted in a body 6. In Fig. 1, two such canters are positioned opposite to one another so as to process two opposing sides of a round log 7 fed through the space between the canters. In the canter to the left in Fig. 1, the process- ing means 4 are not indicated, and it appears that circu¬ lar holes 8 are formed in the cone 2¹ to serve as attach¬ ments for the processing means with associated holders and to enable the passage of chips through the canter to the back thereof. As can be seen, the truncated cone 2' essen- tially is a hollow casing and the circumferential surface of the cone is not completely even but formed with shoul¬ ders 9 in the area adjacent to the holes 8.

Fig. 2 is a front view of the canter according to the invention. As shown in the Figure, there are provided two shoulder portions 9 which in a spiral turn follow the cir¬ cumferential surface of the cone. Thus, also the holes 8 are arranged spirally. In the holes are provided process¬ ing means 4 mounted on a holder 11. In Fig. 2, only about one fourth of the holes and the processing means are indi- cated, but it is to be understood that processing means are mounted at all the points marked in the Figure. As appears, the fine-canter 3 is equipped with cutting knives 10 for finishing the log surface.

Figs 3-5 illustrate in more detail the design of a processing tool according to the invention. The tool includes two cutting knives 4, 4' and a holder 11. As best appears from Fig. 5, the holder comprises a knife-holding element 12 and a fastening element 13. The knife-holding element 12 extends through the hole 8 in the boundary wall of the cone 2' and has an outer end surface 14 located outwardly of the circumferential surface of the cone, as well as a front chip-guiding surface 15 which is essen¬ tially flat and perpendicular to the tangent of the cir¬ cumferential surface. The inner end of the knife-holding element is connected, suitably by welding, to the fasten- ing element 13 which extends a distance rearwards from the knife-holding element 12 and is formed with a hole 16. A threaded rod 17 extends through the hole 16, and its outer end is screwed into a threaded hole 18 formed in the boun¬ dary wall of the cone 2'. Two nuts 19, 19' are screwed on the rod 17 and arranged one on each side of the fastening element 13. Owing to the joining of the nuts 19, 19' and the fact that the hole 16 is unthreaded, the outer end surface 14 of the holder 11 can be set in different pro¬ jecting positions relative to the circumferential surface. In the inventive embodiment illustrated in Figs 1-5, use is made of square cutting knives in the form of index¬ able inserts which are of a substantially flat shape and have an upper, flat surface 20 and a lower, flat surface 21, which are parallel, as well as four cutting edges 22, 22' . All the cutting edges are bevelled in the same direc¬ tion so that the lower surface 21 is much smaller than the upper surface 20, and the cutting knife is thus given the shape of a truncated pyramid. Each of the knives is fixed by a throughgoing screw 23 whose head is countersunk in the upper surface 20, so that no part thereof projects above the upper, flat surface 20. As shown in Figs 4 and 5, the cutting knives are mounted in a recess or seat 24 in the front part of the outer end surface 14. The seat has a bottom surface 25 and, inclined relative thereto, a lateral surface 26. The width of the bottom surface 25 equals the width of the lower surface 21 of the cutting knife, and the width of the lateral surface 26 essentially equals the width of a bevelled surface 29 of the cutting knife. In addition, the angle between the bottom surface 25 and the lateral surface 26 equals that between the lower surface 21 and one of the bevelled surfaces 29. It appears from Fig. 5 that the edge between the bevelled surface 29 and the lower surface 21 is flush with the front chip-guiding surface 25 of the knife-holding ele¬ ment. Also, the cutting knife is downwardly inclined in the rearward direction, i.e. the parallel, upper and lower surfaces 20 and 21 are inclined relative to the tangent of the circumferential surface. This is meant to prevent the upper surface 20 from being worn in operation, and the angle suitably is 1-10°, preferably 3-7° or about 5°. Fur¬ ther, the largest width of the cutting knives conveniently is 17-25 mm, preferably about 21 mm. The thickness of the cutting knives conveniently is 4-8 mm, preferably about 6 mm.

Fig. 3 is a front view of the holder 11. As can be seen, both the outer end surface 14 and the seat 24 are angled, i.e. they comprise a portion 14 and 24, respec¬ tively, whose plane is perpendicular to the axis of rota¬ tion of the cone, as well as a portion 14* and 24', respectively, whose plane is inclined relative to the axis of rotation and conveniently is parallel to the circumferential surface of the cone. As appears from

Fig. 3, a cutting knife 4 is mounted in the seat portion 24 perpendicular to the axis of rotation, while another cutting knife 4¹ is mounted in the inclined seat portion 24' . The two cutting knives are so positioned that the two adjoining cutting edges substantially are applied against one another. This creates an elongate processing edge structure composed of two cutting edges 22, 22' which are inclined relative to one another. The cutting edge 22 is substantially perpendicular to the axis of rotation of the canter and will, in processing, cut the wood parallel to the fibres, whereas the cutting edge 22' will cut the wood transversely of the fibres. Convenient¬ ly, the angle between the two cutting edges 22, 22' is 130-160°, preferably 140-150° or about 145°.

Fig. 4 is a top view of the holder, also indicating the outlines of the hole 8 formed in the boundary wall of the cone. As appears from the Figure, the rear surface 27 of the knife-holding element 12 has an arcuate shape and has essentially the same radius as the hole 8. The holder is so positioned that the rear surface 27, and especially those lateral portions of the surface 27 that are located on either side of the front surface 15, will be applied against the circumferential edge of the hole. This pre¬ vents the holder from being turned about the threaded rod 17 in operation. However, the rear surface 27 need not have a shape which entirely corresponds to the circum- ference of the hole, but turning may also be prevented by the holder being applied against the hole at only two lateral points. It also appears from Fig. 4 that the holder takes up less than half of the hole area and that the cutting edges 22, 22' are positioned on a line running essentially through the centre of the hole. This has the advantage of giving a large free space, thus making it easy for the chips to pass through the canter.

As appears from the foregoing and the accompanying drawings, the device according to the invention presents obvious advantages. Thus, it enables the formation of an angled cutting edge by the use of small and simple cutting knives in the form of indexable inserts which can be turn¬ ed several times when the cutting edges are worn and which further are so inexpensive that they, when all the cutting edges are worn, can be thrown away and replaced with new ones. Since the knives are not to be sharpened, and thus need not be adjusted as to position owing to a decrease in dimensions, the holder can be set once and for all, and the seats 24, 24' will consequently provide a given, fixed position for the knives. Also mounting and dismounting of the knives is considerably facilitated by the fastening screws 23 being accessible from the outside, which means that these operations can be performed by one man.

Figs 6 and 7 illustrate a second embodiment of a holder 30 and two cutting knives 31 and 32 mounted there¬ on. In this embodiment, the one cutting knife 31 is rec- tangular and has two cutting-edge-forming long-side edges 33, 33' and two short-side edges 34, 34' without any cut¬ ting edges, whereas the other cutting knife 32 is of the type described above, i.e. it is of square shape and has four cutting-edge-forming side edges 35. Both the cutting knives are flat and have parallel upper and lower sides and linear cutting edges. The rectangular cutting knife 31 conveniently has a size of about 27 x 20 mm. The holder 30 is adapted to be mounted in one of the above-mentioned holes 8 in the canter, the cutting edge 33 of the rectan- gular cutting knife 31 extending radially perpendicular to the axis. >f rotation o_f the canter, and-JΛe cutting edge 35 of the square cutting knife 32 extending essentially parallel to the circumferential surface of the cone from that end of the cutting edge 33 of the rectangular cutting knife 31 which is located furthest away from the axis of rotation. It appears from Fig. 7 that the square cutting knife 32 is mounted in a rotated position relative to the rectangular cutting knife 31. Although the cutting edges 33 and 35 in this top projection presents a continuous line, they are angled relative to one another in such a manner that the end of the cutting edge 35 of the square cutting knife 32 that is located furthest away from the cutting edge 33 of the cutting knife 31 is pivoted for¬ wards in the direction of rotation. This is intended to enable disposing a corner portion 36 of the cutting knife 32 above the upper surface of the cutting knife 31, more precisely the corner portion closest to the rectangular cutting knife 31, as shown in the front view in Fig. 6. In operation of the canter, the corner portion 36 will thus cut the fibres of the chips in a distinct manner, without any risk of a formation of splintery and uneven chips that may cause problems in later handling. The corner portion 36 may suitably project about 0.5 mm above the upper sur¬ face of the cutting knife 31.

In this second embodiment of the invention, the holder 30 differs from the holder 11 in the first embodi- ment in that it, as seen from above, has the shape of a part circle with two lateral portions 37 and 38 which between them define a recess 39. This recess is designed to guide the chips to the interior of the canter cone. In the lateral portions 37 and 38 are formed threaded holes 40 for screws (not shown) which, when the holder is mount¬ ed in the canter, are intended to be tightened against the circumferential surfaces of the hole 8. Otherwise, the holder has cutting-knife seats equivalent to those of the previously-described holder, except for the seat of the square cutting knife 32 being angled relative to the seat of the.rectangular cutting knife 31..To-prevent the chips from getting stuck in the wedge-shaped opening formed between the cutting knives, a groove 41 is formed in the upper side of the holder and extends rearwards and away from the processing edge.

A distinctive feature of the two embodiments describ¬ ed and illustrated herein is that the largest flat, upper surface 20 of the indexable insert constitutes a release surface, whereas the bevelled lateral surface 26 serves as chip-breaking surface. This facilitates mounting and dis¬ mounting of the inserts, since the throughgoing fastening screw 23 thus becomes easily accessible from the outside of the canter cone.

It goes without saying that the invention can be modified in many ways within the scope of the appended claims. Thus, angles and dimensions of the component parts can be altered considerably. Further, the cutting knives need not have exactly four or two cutting edges, but may also have three cutting edges. Nor is the invention restricted to an arrangement with only two cutting knives mounted adjacent to one another. For instance, two cutting knives can be mounted in the seat 24 perpendicular to the axis of rotation, and two cutting knives can be mounted in the inclined seat 24'. Of course, the canter need not have a first rough-canter member supporting processing tools according to the invention on the conical circumferential surface of the canter and a second fine-canter member of another design at the narrow end of the cone. Thus, pro¬ cessing tools according to the invention may successfully be provided also at the narrow end of the cone for finish¬ ing the lateral surfaces of the wood block. For this pur- pose, however, use should not be made of a processing tool according to the second embodiment in which the corner portion 36 of the inclined cutting knife 32 projects above the upper side of the cutting knife 31 perpendicular to the axis of rotation. If this is done, the finished sur- face will present arcuate grooves.

Claims

1. Canter for processing a log (7) by directly cut- ting into chips the material removed from the log, said canter comprising a rotatable canter member (2) which essentially has the shape of a truncated cone and on whose circumferential surface are provided replaceable process¬ ing means (4) for cutting away material from the log, said processing means having a cutting edge structure which is composed of two substantially straight cutting edges (22, 22' ) at an angle to one another, c h a r a c t e r i s ¬ e d in that the cutting edge structure is composed of at least two separate, flat processing means (4, 4') in the form of indexable inserts each having at least two sepa¬ rate, straight cutting edges (22, 22'), said processing means being so angled to one another that a first cutting edge (22) extends substantially radially perpendicular to the axis of rotation of the canter member, whereas a second cutting edge (22' ) extends at an angle to said first cutting edge,, preferably in parallel with the cir¬ cumferential surface of the cone.

2. The canter of claim 1, c h a r a c t e r i s ¬ e d in that the individual processing means (4, 4') are in the shape of square plates having four cutting edges (22, 22').

3. The canter of claim 1 or 2, c h a r a c t e r ¬ i s e d in that the processing means (4, 4') are mount- able in given positions in recessed seats (24, 24') in order to obviate the need of positional adjustment of said means when mounted.

4. The canter of any one of the preceding claims, c h a r a c t e r i s e d in that the processing means (4, 4'j are mounted on a holder (11).

5. The canter of claim 4, c h a r a c t e r i s ¬ e d in that the holder (11) includes a knife-holding ele¬ ment (12) and a fastening element (13), the latter being connected to the inside of a conical boundary wall (2' ), while the knife-holding element extends through a hole (8) formed in the boundary wall.

6. The canter of claim 4 or 5, c h a r a c t e r - i s e d in that the holder (11) is displaceable to diffe¬ rent projecting positions relative to the conical boundary wall (2') to enable adjustment of the level of the pro¬ cessing means (4, 4* ) above said wall.

7. The canter of any one of the preceding claims, c h a r a c t e r i s e d in that a corner portion (36) of the inclined processing means (32) projects a distance above the processing means (31) perpendicular to the axis of rotation.

8. The canter of any one of the preceding claims, c h a r a c t e r i s e d in that the cutting edge (35) of the inclined processing means (32) is, as seen from above, at an angle to the cutting edge (33) of the pro¬ cessing means (31) perpendicular to the axis of rotation.

9. The canter of any one of claims 1-4 and 6-8, c h a r a c t e r i s e d in that the holder (30) has two lateral portions (37, 38) which between them define a chip-guiding recess (39), and that threaded screw holes (40) are formed through said lateral portions, said holder being fixable in a hole (8) in the canter member by screws being threaded into the holes (40) and tighten¬ ed against the circumferential surface of the hole (8).