Rotary Cutter for Wood Cutting Machine, and Device for Holding Cutting Elements Thereof

The present invention relates to a holding device for mounting a resharpenable cutting element in a rotary cutter of a wood cutting machine, as well as to a rotary cutter of the latter.

Rotary cutters and holding devices of the above-mentioned general type are known in the art. A known holding device has a supporting member extending over a greater part of the length of the cutting element and having a web which is small as compared with the height of the cutting element and provided with holding tongues extending over a part of the side of the cutting element and having elongated openings. Tightening screws extend through these openings so that the supporting member can displace somewhat radially over the rear surface of the cutting element and be fixed. An abutment surface fixedly arranged in the body part of the cutter determines a projecting length of the cutting element and is located so that the supporting member loosely lies against the same. A wearing member is fixed in the body part of the cutter via a somewhat radially acting locking member and arranged so that the cutting element abuts with its rear surface against the wearing member. Finally, a centrifuging wedge member presses against the wearing member. Such a rotary cutter and its holding device is disclosed, for example, in the German Gebrauchsmuster No. 8,002,428. The cutting element lies with its front surface loosely against a clamping strip which is held in the body part via a locking member and is actuated by a centrifuging wedge member which presses the clamping strip against the front surface of the cutting element and thereby the cutting element against the wearing member. The cutting element is loosely introduced, together with supporting member screwed therewith, into an approximately radially extending insertion slot of the wearing member and abuts with assured abutting face of the supporting member loosely against the above-mentioned abutment surface in the body part of the cutter. In the above-described known construction, the cutting element is thereby held exclusively in a force transmitting manner. In order to prevent that the centrifugal wedge member which is pulled radially outwardly under the action of the centrifugal force changes the position of the cutting element in the cutter body and thereby the projecting length of the cutting element over the outer surface of the body part, the clamping strip between the centrifuging wedge member and the front surface of the cutting element which is form lockingly fixed in the body part is provided. The abutment surface which supports the supporting member is formed as a holding strip which is screwed with the body part and located, as seen in radial direction, under the cutting element as well as the supporting element. A peripheral recess provided in the body part for receiving the holding device must therefore be deeper than the width of the cutting element in order to additionally receive the above-mentioned holding strip.

Accordingly, it is an object of the present invention to provide a rotary cutter and a holding device therefor, which avoid the disadvantages of the prior art.

More particularly, it is an object of the present invention to provide a rotary cutter and a holding device which have a simpler construction .

In keeping with these objects, and with others which will become apparent hereinafter, one feature of the present invention resides, briefly stated, in a holding device in which a wearing member has a locking groove which opens toward a cutting element and forms an abutment surface, so that a web of a supporting member for the cutting element is inserted in the locking groove in a form-locking manner, and the centrifuging wedge member lies with its wedge surface directly against a front surface of the cutting element.

The form-locking connection which was provided in the prior art for the clamping strip is formed in accordance with the invention behind the rear surface of the cutting elements between the supporting member and the wearing member. The supporting member of the cutting element and thereby also the cutting element screwed therewith are held directly in a form-locking manner in the wearing member. The cutting element is also secured in a radial direction from displacement. Because of this it is possible in accordance with the invention to dispense with the clamping strip which was used in the prior-art construction and provide abutment of the centrifugal wedge member directly against the front surface of the cutting element. The inventive holding device is composed of a small number of parts. Because of the absence of the clamping strip for the cutting element, its locking member and holding strip are also dispensed with, and there is a possibility that the locking member which holds the wearing member in the body part is located completely behind the rear surface of the cutting element. For this purpose the peripheral recess which receives the holding device can be formed only with such a depth which is required for receiving the cutting element. There are no more parts which overlap the cutting element. The locking member which holds the wearing member can be formed in conventional manner hook-shaped and formed by a holding strip screwed with the body part of the cutter or fixed in any other way.

In accordance with another advantageous of the present invention, a permanent magnet is arranged in the locking zone of the wearing member so that the web of the supporting member abuts against the permanent magnet. Thereby, the cutting element, the supporting member and the wearing member are inserted into or removed from the body part of the cutter as a set. At the same time, the cutting element which is screwed with the supporting member can be easily separated from the wearing member, for example for sharpening of the cutting element. During grinding process the assembly of the cutting element and the supporting member remains maintained. The setting of the sharply ground cutting element is performed by a special setting device, wherein the web of the supporting member forms a reference edge. For setting, the tightening screws are somewhat released and after the adjustment of the cutting element are again fixedly tightened.

In accordance with yet another advantageous feature, the centrifugal wedge member abuts against the front surface of the cutting element via a releasably connectable wearing strip. The wearing strip is independent of the length of the produced chips can be easily exchanged.

The holding device in accordance with the present invention is basically suitable for a tooth (comb) cutter or so-called double tooth (comb) cutter; however, it is also suitable for a cutter with a throughgoing cutter edge. In this case, the wearing member may be provided with an insertion slot in which rectangular scratcher plates are inserted in a form-locking manner and retained by the cutter element. Each scratcher plate has a pin extending beyond both sides of the former and engaging in an insertion groove of the wearing member, the groove being opened toward the cutting element.

The holding device in accordance with the present invention is also designed for switching from the tooth cutters to cutters with throughgoing cutting edges. The new holding device provides for a high adjustment accuracy for the cutting element and leads to lower additional costs for grinding of the cutting element. The wearing member arranged behind the cutting element can simultaneously serve as a scratcher support.

The novel features which are considered as characteristic for the present invention are set forth in particular in the appended claims. The invention itself, however, both as to its construction and its method of operation, together with additional objects and advantages thereof, will be best understood from the following description of specific embodiments when read in connection with the accompanying drawings.

FIG. 1 is a view showing a section of a rotary cutter with a holding device for cutting elements;

FIG. 2 is a fragment of a plan view of the inventive holding device as seen in direction A in FIG. 1;

FIG. 3 is a plan view of a rear surface of a cutting element connected with a supporting member and,

FIGS. 4 and 5 are perspective views illustrating parts of FIGS. 1 and 3.

A rotary cutter and a holding device for holding a plurality of cutting elements in a body of the rotary cutter is shown in the drawing, wherein one of the cutting elements is illustrated and identified by reference numeral 1. The cutting element 1 has in the shown embodiment a throughgoing (uninterrupted) cutting edge.

The holding device includes a supporting member identified by reference numeral 2 and extending over a greater part of the length of the cutting element. It has a web 2a which is small as compared with the height of the cutting element and is provided with holding tongues 2b. The tongues extend over a part of the height of the cutting element and has elongated openings 3, as can be seen from FIG. 3. Tightening screws 4 extend through the elongated openings 3 so that the supporting member is displaceable over a rear surface 1b of the cutting element 1 substantially in radial direction and fixable.

A holding member 6 is screwed by a screw 6' in a body 5 of the cutter and has a hook-shaped locking part 7. A wearing member 8 engages in the locking part 7. The cutting element 1 abuts with its rear surface 1b against the wearing member 8. The wearing member 8 has a locking groove 9 which opens toward the cutting element 1. The web 2a of the supporting member 2 is inserted into the locking groove 9 in a form-locking manner. The term "form-locking" is utilized here to identify an interengaging connection in which shapes of respective members complement each other.

The locking groove 9 forms an abutment surface 9a for the web 2a of the supporting member 2 and thereby determines a projecting length of the cutting edge of the cutting element beyond the outer surface of the body part of the cutter. A permanent magnet 10 is arranged in the locking groove 9. The above-mentioned web 2a of the supporting member 2 freely abuts against the permanent magnet 10.

The wearing member 8 has moreover insertion slots 11. Rectangular chip breakers 12 are inserted in the insertion slots 11 in a form locking manner. The chip breakers 12 are retained in the insertion slots 11 by the cutter 1. Each scratcher plate 12 has a pin 13 extending outwardly beyond the same at both its sides. The wearing member 8 has, on the other hand, insertion grooves 14 which are open toward the cutting element 1. The above-mentioned pins 13 engage in the insertion grooves 14, as can be seen from FIG. 2.

The holding device further has a centrifuging wedge member 15 which lies against a front surface 1a of the cutting element 1 via a wearing strip 16 releasably connected with the centrifugal wedge member 15. The centrifugal wedge member 15 presses the cutting element 1 with its rear surface 1b against the wearing member 8. The wearing strip 16 of the centrifuging wedge member 15 is formed wedge-shaped in its region which faces toward the cutting edge of the cutting element 1.

It will be understood that each of the elements described above, or two or more together, may also find a useful application in other types of constructions differing from the types described above.

While the invention has been illustrated and described as embodied in a rotary cutter and a holding device therefor, it is not intended to be limited to the details shown, since various modifications and structural changes may be made without departing in any way from the spirit of the present invention .

Without further analysis, the foregoing will so fully reveal the gist of the present invention that others can, by applying current knowledge, readily adapt it for various applications without omitting features that, from the standpoint of prior art, fairly constitute essential characteristics of the generic or specific aspects of the present invention.