Background of the Invention In a planing machine of the kind the cutter is adapted to be used, a plural- ity of cutter units, normally six, are arranged for simultaneous planing of the top, bottom and side surfaces of a plank.

On a cutter, it is desirable to have relatively many recesses having cutting edges. Several cutting edges entail an increased milling capacity, an improved fin- ish of the planed surfaces and a lower noise level. Normally, a cutter of 160 mm in diameter accommodates six cutting edges. Here, the clamping and locking of each cutting edge constitute an important aspect. On one hand this has to be safe of course, and on the other hand it should be simple and preferably require a small circumferential space. The peripheral space of the clamping device is one of the factors that delimit the number of cutting edges that can be arranged on a cutter.

At conventional technique, the locking body that clamps the respective cutting edge is normally attached to screws directed in the circumferential direc- tion, which results in a relatively large circumferential extension of the clamping device, especially if the same is arranged adjacent to the chip breaker on the front of the cutting edge.

By WO 97/16276 a cutter is previously known, where the clamping of each cutting edge is attained by means of an essentially radially directed wedge clamped by means of a likewise radially directed screw. The wedge co-operates with the edge holder, and both said elements are arranged in a recess that widens outwards. The wedge tapers outwards and the edge holder widens outwards, and both of them co-operate along an oblique plane surface that locks the edge holder

by means of a force directed outwards from the wedge. In order to hold the entire assembly, the second surface of the edge holder is knurled in order to co-operate with corresponding knurls in one of the walls of the recess. Thereby, the construc- tion becomes relatively complicated and also this is likely to require a relatively large space in the circumferential direction.

In FR 2 616 367 and EP 122 334, other examples of essentially radially directed tightening wedges and appurtenant tightening screws are disclosed. In both cases, however, the wedge and the recess have outwardly widened cross- sections that may pose a risk of the clamping losing the grip or demands special measures in order to counteract this.

Further, in FR 610 027, a radially directed tightening wedge having a radi- ally outwardly abating cross-section is disclosed, wherein the wedge is pressed outwards by means of tightening screws. Tightening of the same is carried out from the outside through holes in the wedge. Said holes impede an optimum chip release, which is of importance at high speeds, such as above 6000 r/min.

The purpose of the present invention is to provide a planing cutter having, even at high speeds, efficient, space saving, safe and simple attachment of the cutting edge elements and which does not have negative impact of the chip release.

Description of the Invention According to the invention, the purpose stated has been attained by each of the locking bodies being provided with at least one radially inwardly facing press-contact surface and at least one essentially axially directed wedge being pressed-in between the press-contact surface and a support surface in the bottom end of the recess.

In this manner, to press out the locking body from below by means of wedge action facilitates uncomplicated achievement of a large press-contact force from the locking body against the cutting edge element, so that the position of the cutting edge element becomes securely fixed, even at high rotational speeds.

Neither does the tightening of the locking body require additional space in the peripheral direction, which enables an increased number of cutting edge elements on a given envelope surface. Furthermore, by virtue of the wedge being without cavities, the same can be made narrower in the peripheral direction, which saves

additional space. Furthermore, the lack of holes from the outside through the wedge involves that no disturbance of the chip release occurs.

According to a preferred embodiment of the invention, in the axial direction the press-contact surface forms an angle to the support surface. Thanks to this angulation, only one wedge is required in order to attain the wedging action. Two co-operating wedges would have been needed should said surfaces have been parallel.

According to another preferred embodiment, the press-contact surface forms an angle to the axial direction of the planing cutter. This is a simpler and more expedient alternative compared to the support surface having a correspond- ing angular adjustment.

According to another preferred embodiment, the press-contact surface comprises a first and a second section, wherein each section extends from an axial end each of the locking body and forms from respective directions an acute angle to the axial direction of the planing cutter and that a wedge is pressed in between each section and the support surface.

By such an embodiment a symmetrical clamping of the wedge can be accomplished. Thereby, the risk that unbalanced forces may appear is eliminated.

Furthermore, the safety of the fixing of the locking body in the axial direction is increased.

According to another preferred embodiment, a locking device is arranged at each wedge for fixing of the axial position of the wedge.

In doing so, it is assured that the wedge does not risk to be pressed axially backwards so that the setting is released.

According to another preferred embodiment, an actuator is arranged at each wedge in order to displace the wedge in the axial direction, which actuator also constitutes locking device.

By means of an actuator, the pressing in of the wedge in position is simpli- fied, and the press-contact force required for the wedging action can be adapted to a suitable value. Furthermore, having the actuator also serving as a locking device contributes further to the achievement of a simple construction.

According to another preferred embodiment, the actuator includes an axi- ally directed screw arranged in an axially directed screw hole in the cutter body, a

carrier element axially fixed in relation to the screw, and a slot recessed in the wedge, into which slot the carrier element extends.

This constitutes an appropriate construction of the actuator enabling the wedge to be pressed in at great force whilst the actuating force becomes moder- ate.

According to another preferred embodiment, at each axial end, each cut- ting edge element has a side edge having a set of grooves, wherein at least one groove in each set is in engagement with a pin that protrudes from a side wall of the recess, wherein the number of grooves in each set being in engagement with a pin is lesser than the total number of grooves in the set.

By means of such an embodiment, an adjustment of the radial position of the cutting edge element after being worn down and resharpened is facilitated, wherein the bond between groove and pin provides an additional security against radial offsets of the cutting edge element.

The above-mentioned preferred embodiments of the invented planing cutter are defined in the claims depending on claim 1.

The invention is closer explained by the following detailed description of advantageous embodiment examples of the same with reference to the appending figures.

Brief Description of the Drawings Fig. 1 is an end view of a quadrant of a planing cutter according to the invention.

Fig. 2 is a cut along the line ll-ll in fig. 1.

Fig. 3 is a cut as in fig. 2 but only through the locking body.

Fig. 4 is an end view of the locking body in fig. 3.

Figs. 5-12 illustrate, in cross-section as in fig. 2 but on a reduced scale, different steps in assembling and disassembling of the locking body.

Disclosure of an Advantageous Embodiment Example Fig. 1 illustrates a planing cutter according to the invention in an end view.

Only a quadrant of the planing cutter is shown. The planing cutter consists of a cut- ter body 1 and a number of cutting edge elements 2, each of which having an appurtenant locking device in the form of a locking body 3. Each cutting edge ele-

ment 2 and appurtenant locking body 3 is arranged in a recess 4 in the envelope surface of the cutter body. In the example shown, the number of recesses is 24 and the diameter of the planing cutter is 260 mm.

Each recess 4 and the cutting edge element 2 and locking body arranged therein extends axially across essentially the entire width of the cutter body 1.

Each recess extends radially into the cutter body 1 some distance and has a bot- tom end 5 at the radially innermost end thereof. As is seen in the figure, the direc- tion of the recesses deviates somewhat, approx. 20° from a sheer radial direction.

The locking body 3 in each recess has a radially inwardly turned notch 6. In the notch, two wedges are fixed, only one 7 of which is shown in fig. 1. Adjacent to each wedge 7, a combined actuator and locking device 9 is arranged. The same consists of a screw 20 having a hexagon socket 10 and a flange 22. The flange 22 of the screw extends into a slot at the underside of the wedge. The slot is situated in a radial plane and is not visible in fig. 1.

When the locking body 3 is pressed radially outwards by the wedges, in a way which will be closer described below, then the wedge profile of the locking body 3, in co-operation with the likewise, in profile wedge-shaped recess 4 will press the cutting edge element 2 against one of the side walls of the recess, effi- ciently clamping the same.

In fig. 2, which is a cut along the line II-II in fig. 1, it is closer illustrated how the wedges 7,8 co-operate with the locking body 3 and how they are actu- ated and locked. By one of the sides thereof, the locking body 3 thus abuts against the cutting edge element 2, essentially obscured in the figure. In the shown cut, the locking body 3 has, i. e. through the notch 6 thereof, a trapezoidal shape. The oblique surfaces at the underside of the locking body 3 constitute press-contact surfaces 13,14, against which a wedge 7,8 each is pressing. At the underside, each wedge 7,8 has support from a support surface 15 that in the shown example constitutes a part of the bottom end of the recess 6. In the underside of each wedge, a slot 16,17 is recessed.

Closely inside the wedges, an axially directed threaded bore 18,19 extends from each side. In each bore, a screw 20,21 is screwed in. Each screw is provided with a flange 22,23 that extends into the slot 16,17 in the respective adjacent wedge 7,8. By means of the screws 20,21, the flanges 22,23 thereof and the slots 16,17 co-operating with the flanges, it is achieved that the respective

wedge can be actuated at assembling and disassembling and hold the respective wedge in the axial position thereof.

The wedges 7,8 push with great force at the underside of the locking body 3 so that the same is pressed upwards and brings about the clamping of the cut- ting edge element 2, described in connection with fig. 1.

In the shown example, the wedge angle is 6°. In correspondence thereto, each support surface 13,14 forms an angle of 6° to the axially extending support surface 15 at the bottom end of the recess.

In fig. 3, the locking body 3 is illustrated alone in a longitudinal cut through the same, and in fig. 4, it is shown in an end view. In fig. 4, the notch 6 recessed in the underside of the locking body and one 14 of the oblique press-contact surfaces 13,14 are more apparent. The parts of the locking body 3 that extend downwards of each side of the notch 6 end in a plane that is axially directed. At the axially utmost situated ends of the locking body, said parts 24,25 are provided with recesses 26 in order to accommodate the flange 22,23 of the respective screw situated inside.

For further understanding of the invention, in connection with the figures 5-12, it is now described how the locking body is assembled, clamped, released and disassembled.

As is shown in fig. 5, the locking body 3 is pushed axially from the end wall into a recess in the envelope surface of the cutter body until it reaches the mid position thereof.

In fig. 6 is shown how each wedge 7,8 is threaded in from respective end wall to abutment against the press-contact surfaces 13,14 of the locking body, so that the locking body is lifted outwards. At the same time each screw is brought in towards the corresponding bore.

In fig. 7 is shown how each screw 20,21 is screwed in into respective bore 18,19, wherein the flange 22,23 of the respective screw by the engagement thereof in the notch 16,17 of the adjacent wedge 7,8 presses the same along.

Fig. 8 displays the whole in an assembled state, wherein the axial outer ends of the wedges 7,8 are aligned with the end walls of the cutter body. Thus, the position in fig. 8 corresponds to what is illustrated in fig. 2.

Releasing of the locking body, for instance for resharpening of the cutting edge element, takes place as is illustrated in fig. 9 by the screws being unscrewed

from the bores thereof, thereby pulling along the adjacent wedge by the flange- notch grip.

Then the screws and the wedge (fig. 10) are removed, whereupon one knocks slightly at the locking body radially inwards (fig. 11) so that the same can be drawn out axially (fig. 12).

As is seen in, for instance, figs. 1 and 12, the cutting edge element 2 has, at each axial end, a side edge 11 having a set of grooves 12. A pair of pins 27, arranged protrudingly from one side wall of the recess 3 adjacent to each side edge, engage into two of the grooves 12 in order to additionally fix the cutting edge element radially. After resharpening of the cutting edge element, the same is posi- tioned so that the pins 27 engage in new grooves situated further in.