AN ARRANGEMENT AT A DISC-SHAPED ROTATABLE TOOL

Abstract: A circular saw blade (4) is arranged to be mounted, via a spacer disc (8), for rotation in its plane by means of screwed joints (20, 30) against the top side of a rotatable conical reducer disc (2), which together with the tool disc forms a reducer disc unit, which is intended to be included together with a further similar reducer disc unit, with the units mounted with their tool discs (4) facing each other, in a reducing plant for plan reducing timber. The screwed joints include threaded sleeves (18-24), which are arranged to extend, optionally from a desired side of the tool disc (4), recessed (16, 16A) therein, through mutually aligned holes (14, 14A, 12) in the tool disc (4) and separate spacer disc (8), for cooperating with a screw introduced from the other side of the mounting surface (6).

Description: An arrangement at a disc shaped rotatable tool . The present invention relates to an arrangement at a disc shaped rotatable tool , such as a circular saw blade, in accordance with the preamble of claim 1. Within the saw milling industry so called reducer plants are used for plane reducing timber that shall be sawn lengthwise into planks. Such a reducer plant includes two mutually oppositely arranged shipper discs, between which the timber logs are caused to pass in their longitudinal direction while cutting opposite sides of the log to pulp chips. The method is repeated for the two remaining sides by causing the log, rotated by 90°, to pass again through the reducer plant. For obtaining an even surface of the reduced logs each shipper disc on its top side facing the other chipper disc carries a circular saw blade. This blade thus operates in the length direction of the log together with the corresponding shipper disc during the reducing operation. In one embodiment, existing on the market, of such a so called reducer blade, the blade on one side carries a fixed spacer ring. The blade is mounted against the corresponding mounting surface of the chipper disc by means of screwed joints passing through the spacer ring and the blade. This screwed joints include screws introduced from the rear side of the chipper disc and screwed into the threaded holes in the spacer ring and the saw blade. The main function of the spacer ring is to provide for the screwed joint a sufficiently long thread engagement for the screw. The described saw blade has the disadvantage that it is not reversible and therefore requires resharpening comparatively often. Of course, this is particularly disadvantageous if the saw blade has to be sent for regrinding in another place. For a reversible saw blade the number of such regrinding events would obviously be halved. For this purpose the saw blade of another embodiment existing on the market has been executed with double thickness right to the saw teeth, which makes the blade reversible, but simultaneously results in an expensive and clumpsy tool. Another disadvantage with this solution is the additional wear to which the threaded holes in the saw blade are exposed by the reversal of the threaded engagement with the corresponding screw when the disc has been reversed. Problems similar to those described above can also appear in other applications where an essentially disc shaped rotatable tool shall be mounted for rotation in its plane via a spacer disc against a mounting surface provided on a drive shaft perpendicularly to the shaft. The object of the present invention is to provide solution to the problem to make the rotatable tool reversible without requiring double thickness of it. This object has been attained in that the arrangement according to the invention has obtained the features stated in claim 1. The invention shall now be described more closely below with reference to the attached drawings, on which Fig. 1 schematically in perspective shows an exploaded view of a reducer device of the kind stated above with the reducer blade and elements cooperating therewith shown more in detail, Fig. 2 is a side view, partly in section, for illustrating the realization of a screwed joint connecting the reducer blade with the chipper disc, and Fig. 3 in perspective shows a threaded sleeve while simultaneously illustrating its cooperation with a corresponding hole in the saw blade. In the Figures 2 generally designates a conical chipper disc, not described any closer, and 4 a saw blade cooperating therewith. The chipper disc 2 and the saw blade 4 are intended to be included in a reducer plant of the kind stated above. The realization and function of such a plant is well known to the man of the art and is therefore not described any closer here. The chipper disc 2 on its top side has a mounting surface 6 against which the saw blade 4 is mounted via a spacer ring 8 by means of screwed joints to be described more closely below. The mounting surface 6 and spacer ring 8 each has a number, 6 in the illustrated embodiment, of unthreaded mounting through holes 10 and 12, respectively. The saw blade 4 has double sets 14 and 14A, respectively, of the same number of unthreaded mounting through holes, every second hole then belonging to the set 14, and every second hole to the set 14A. In one side of the saw blade 4 the holes 14 have a conical recess 16, and the holes 14A have a corresponding conical recess 16A in ,the other side of the saw blade 4. The conical recesses 16, 16A are intended for receiving a corresponding conically shaped head 18 of a sleeve provided with inner threads 20 and having a cylindric shaft portion 22. The total height of the conical head 18 and shaft 22 essentially corresponds to the total thickness of the saw blade 4 and spacer ring 8. On a distance from the end surface of the conical head 18 which is somewhat greater than the thickness of the saw blade 4, the shaft 2 carries a nib 24 intended to engage a corresponding groove 26 in the inside of the hole 12 in order to lock the threaded sleeve 18, 20, 22 against turning. The holes 14 r 14A have corresponding grooves 28 directed in the same direction as the grooves 26 in order to allow, at introduction of the threaded sleeve 18-24 through the hole 14 or 14A, passage of the nib 24 to ultimate engagement into the groove 26 when the conical head 18 of the thread sleeve is located in the corresponding recess 16 or 16A. In this position the threaded sleeve is intended to cooperate with a screw 30, which is introduced from the backside of the chipper disc 2, through the holes 10 into threaded engagement with the threads 20 of the sleeve, as is illustrated in Fig. 2. As should have appeared from the above the described arrangement makes possible that the saw blade 4 can be mounted with either side facing outwardly, in one case six holes 14 and in the other case six holes 14A being used for the screwed joints, consisting of a threaded sleeve 18 - 24 and a screw 30, through elements 4, 6 and 8. The saw- blade is easily reversible due to the fact that after loosening of the screwed joints, the threaded sleeves fit as well in the recesses 16 (16A) of the other side. At exchange of a saw blade the same spacer ring 8 and threaded sleeves 18 - 24 can be used without exchange together with the new saw- blade. As should also have appeared from the above, the empty mounting holes of the saw blade, in the mounted state thereof, i.e. the holes used at side reversed mounting of the blade, are located in front of a plane surface of the spacer ring 8.

Claims: Claims . l.An arrangement at an essentially disc shaped rotatable tool, such as a circular saw blade (4), henceforth termed tool disc, which is arranged to be mounted, via a spacer disc (8), for rotation in its plane by means of screwed joints (20,30) against a mounting surface (6) provided on a drive shaft, perpendicularly to said shaft, e.g. on the top side of a rotatable conical reducer disc (2), which together with the tool disc forms a reducer disc unit, which is intended to be included together with a further similar reducer disc unit, with the units mounted with their tool discs (4) facing each other, in a reducing plant for plane reducing timber, characterized in that the screwed joints include threaded sleeves (18-24), which are arranged to extend, optionally from a desired side of the tool disc (4), and recessed (16,16A) therein, through mutually aligned holes (14,14A,12) in the tool disc (4) and a separate spacer disc (8), for cooperating with a screw (30) introduced from the other side of the mounting surface (6). 2. An arrangement according to claim 1, characterized in that the tool disc (4) contains twice as many holes (14,14A) as the number of intended screwed joints, every second hole having a recess (16,16A) for the threaded sleeve in one side of the tool disc, and the other holes (14A,14) having a corresponding recess in the other side of the tool disc. 3. An arrangement according to claim 1 or 2, characterized in that the threaded sleeves have a conical head (18) intended to fit in a corresponding recess (14,14A) in the side of the tool disc, and a shaft (22) shaped to fit unturnably in the hole (12) of the spacer disc (8). 4. An arrangement according to claim 3, characterized in that the shaft (22) has a nib (24) intended to engage a recess (26) in the hole (12) of the spacer disc (8) . 5. An arrangement according to claim 3 or 4, characterized in that every second hole (14,14A) of the tool disc has a recess (16,16A) cooperating with the conical threaded sleeve head (18), only in one side of the tool disc, and the rest of the holes have a corresponding arrangement side reversed in the tool disc.

Applicants: LAANGSHYTTAN SLIPSERVICE AB
Application year: 1988
Main classification: B27B33
IPC codes: B27B5, B27B33, F16B33