FI70168C - FOERPROFILFLISHUGGARE AVSETT FRAESHUVUD - Google Patents

Description

70168

BLADE FOR PROFILE CUTTERS

The invention relates to a blade head for profile chippers, which has a blade body which supports chipping blades at circumferential points 5 and which has circular saw segments arranged on the end face of the blade, each extending between two chopping blades and having thickened mounting flanges compared to saw teeth.

In profile chippers, round tree trunks or trolls are fed between opposed used blade heads. The blade ends form two opposite sawing surfaces on the frame or only and chop the wood segments outside these sawing surfaces into a chip for use.

Since this application, which is needed above all in the manufacture of chipboard and cellulose, consists of relatively coarse chips with a defined minimum fiber length, only a few chipper blades, most preferably two or three, are placed on the edges of the blade ends.

It is known to fit on the end surface of a blade end a complete circular saw blade, which is not divided into 20 parts, which forms a sawing surface on the body or only. The sawing operation proceeds before the chipper-blade cutting to prevent cracks due to the impact-like contact of the chipper blades from advancing to the body or to the rest of the body alone. In this case, there may be on-25 problems between the end face of the chipper blades and the circular saw blade. Wood particles which apply undesired lateral forces to the circular saw blade can penetrate into this formed gap, in addition to which the strong friction that occurs causes strong heat generation. to the space between the circular saw segments (DE patent publication 22 19 999). When the space between the two circular saw segments is greater than the distance between the two saw teeth in the circumference, the first saw teeth of the circular saw segments strike the wood 5 and are thus subjected to a higher load than the subsequent saw teeth. In order to avoid this impact-like load and to make the load of all the saw teeth even more straight in the known blade end, the front part of each circular saw segment is pulled inwards in the direction of a fine radius. The length by which each saw tooth protrudes radially from the outer circumference of the thickened mounting flange is then equal for all saw teeth and must be selected to be at least equal to the body or feed distance between the contact of the two hak-r 15 disc blades.

The retraction of the teeth at the front of each circular saw segment reduces the impact load of the teeth »but results in an uneven feed per saw tooth, which in turn leads to an uneven loading of the cutting power of the individual saw teeth in each segment and thus a decrease in sawing power. Above all, however, the transverse forces that occur still cause a relatively large bending load on the front saw teeth of each circular saw segment. This bending load requires a relatively large tooth thickness, which in turn causes a relatively wide saw gap and thus a relatively large proportion of economically unusable sawdust.

The object of the invention is thus to realize a blade head as mentioned in the introduction 30 so that a uniform and minimal bending load is obtained for all saw teeth of each circular saw segment, which enables the thickness of the saw teeth to be reduced so that losses in the form of sawdust are reduced.

701 68 3 This object is solved according to the invention in that in the radial direction of the thickened fastening flange the outer circumference runs eccentrically with respect to the axis of the blade so that the distance between the fastening flange and the saw teeth increases from the beginning to the end of the circular saw segment. In this case, the situation in which all the saw teeth are located in a concentric or slightly eccentric trajectory with respect to the blade axis in each case, the first saw teeth of the circular saw segment 10 near the chipper blade so that their bending load becomes less.

15 Only the teeth at the rear of the circular saw segment, which have to have a greater penetration depth due to the feed or the feed alone, protrude radially farther from the thickened mounting flange.

Experience has shown that only minor transverse forces occur in the circular saw segment at this point, so that the bending load at this point also remains small. Therefore, the thickness of the saw tooth can be selected to be relatively small, resulting in a narrow saw gap and thus small sawdust losses.

For manufacturing reasons, it is particularly advantageous if the fastening in the radial direction of the flange has a circumferential arc running eccentrically with respect to the axis of the blade head. Theoretically, the fastening as the optimal shape of the outer circumference of the flange would be a spiral curve, but with the conventional circumference lengths of such circular saw segments for this optimal shape, a sufficiently accurate approximation with eccentric circular arcs can be obtained. The advantage of a circular arc is then that it is substantially simpler to manufacture and machine by turning 35 or rotary grinding.

701 68 1+

With the implementation according to the invention, it is achieved that the reinforced fastening edge is closer to the tips of the teeth. This is important because the saw blades following the chipper blades are subjected to large lateral forces, for example when cutting round wood on one side and turning it when cutting between opposing blade ends.

Similarly, for manufacturing reasons and also due to the simple and stable attachment to the blade ends 10, it is also advantageous to place the fastening screws of the circular saw segment on a circular arc concentric with the outer circumference of the fastening flange.

The invention will be explained in more detail below in connection with the exemplary embodiment shown in the drawing.

Figure 1 shows an end view of the blade head;

Fig. 2 shows a simplified section along the line II-II in Fig. 1, and

Figure 3 shows a plan view of two opposing blade ends handling a tree trunk 20 fed between them, with only one side of the blade ends shown and the circular saw segments shown in section.

The blade head 1 shown in Figures 1 and 2 has a substantially frustoconical blade body 2 at the end of the shaft of the used blade (not shown). The body 2 of the blade head 25 has two chipper blades 3 on the casing surface of the truncated cone.

The end face 4 of the blade head 1 has a circular saw segment 5 on each circumferential arc between the cutting knives 3. Each circular saw segment 5 has saw teeth 6 evenly spaced 30 on the circumference.

5,70168

In the embodiment shown, the trajectory 9 defined by the tips of the saw teeth 6 is, in the case of both circular saw segments, at least approximately circular with respect to the axis 10 of the blade head. In contrast, in the radial direction, the outer periphery 7a has a circular arc eccentric with respect to the axis 10 of the blade, the radius r of which is offset by an eccentricity a / 2 with respect to the axis 10 of the blade (Fig. 1). This ensures that in the radial direction of the fastening flange 7 the radial distance of the outer circumference 7a and the path 9 of the saw teeth 10 increases from the beginning to the end of each circular saw segment 5 and especially from f corresponding to the minimum penetration depth of the saw teeth 6 (shown in left with eccentricity a / 2 added to the value 15 f + a (right in Figure 2).

It can also be seen from Fig. 1 that the fastening screws of the circular saw segments 5 are likewise in a circular arc which is co-central in the radial direction of the fastening flange 7 with the outer circumference 7a.

Figure 3 shows the situation at the point of contact of the tree trunk 11. It is shown on the left that the saw teeth 6 protrude only slightly over the outer circumference 7a of the fastening flange 7 at the beginning of each circular saw segment 5. Switching blade 3 immediately above the timber body 11 cut by the cutting surface 25 has the effect of moving the body to pass from the body of the cutter head 2 and reaches the blade end of one half turn the position of Figure 3 shown on the right. The penetration depth of the saw tooth 6 is substantially greater in this position, the saw tooth 6 protruding correspondingly more past the outer circumference 7a of the fastening flange 30 7. In this position shown on the right in Fig. 3, the next chipper blade 3 comes into contact.