Patent Application
20170028583
This application is a national phase entry under 35 U.S.C. § 371 of PCT/CH2015/000055 filed on Apr. 14, 2015, which claims priority to Swiss Patent Application 569/2014 filed on Apr. 14, 2014, the entirety of each of which is incorporated by this reference.
The invention relates to a tool head according to the preamble of claim 1, to a cutting insert according to the preamble of claim 21 and to a method for inserting and clamping a cutting insert according to the preamble of claim 27.
DE-OS 36 36 618 discloses a cutter block for cutting woodworking machines, in particular for planning machines. It has a one-piece cutter block body which has a plurality of axially parallel grooves which taper towards the lateral surface and in which sits a respective profiled disposable blade which is clamped by a centrifugal wedge and engages positively into a corresponding profiling of the side face of a retaining ledge located between the disposable blade and the centrifugal wedge. In this respect, the retaining ledge is joined in an unmovable manner to the cutter block body and is elastically deformable. It is arranged at such a distance from the side wall of the groove that, when the centrifugal wedge is released, an interpositioned blade can be easily removed in the longitudinal direction and a new blade can be inserted without practically any clearance. When the centrifugal wedge generates the clamping force by rotating, the retaining ledge is pressed firmly against the disposable blade due to a slight elastic deformation so that said blade is fixedly located in an unmovable manner. However, the blade can only be clamped in a single unchangeable position.
German utility model DE-U-89 14 809 discloses a cutter head for machining wood, plastics and the like, particularly for the longitudinal profiling of strips and boards, having a cylindrical main part which has a plurality of axially parallel grooves which are open towards the lateral surface. A blade is clamped in each groove between a side wall of the groove and a retaining ledge, a tooth system of the back of the blade meshing positively with a corresponding tooth system of the side wall. The groove towards the lateral surface of the main part is tapered in a wedge shape. Arranged in this groove is a centrifugal wedge which firmly clamps the blade between the retaining ledge and the other side wall when the main part rotates.
U.S. patent application No. 2002/0046632 discloses a tool body having one or more tool mounts, into which blades can be inserted which are held by a clamping mechanism. To minimise the tool costs, U.S. 2002/0046632 proposes re-sharpening the blades and removing an equal amount from the bottom of the blade, thus generating a new reference edge. At a distance from the base of the blade, the inserted blades have a groove into which a protruding rib engages, which is configured in the tool mount, when the blade is clamped in the mount. The groove is provided in the flat side of the blade opposite the cutting edge and prevents the blade from being able to slip radially during operation. According to U.S. 2002/0046632, to achieve the same objective, the rib can alternatively be provided on the fixing wedge.
U.S. patent application No. 2005/0265795 discloses a tool head having a tool mount in which a blade can be clamped by a fixing wedge. The blade has a bevel with the cutting edge on the bottom of the blade and opposite the flat side, which bevel creates the necessary free space when the blade is inserted into the opening in the tool mount.
To replace or adjust the blade, the centrifugal wedge is firstly released by a radially inwardly directed force effect, for example by a hammer blow. The retaining ledge which, in the clamped state, is slightly elastically deformed towards the blade, returns into its relaxed position. In this position which is fixed precisely by the stop angle between the two ledges, the seat of the blade is loosened to such an extent that the blade can be easily removed in the direction of the axis of the main part. Thereafter, optionally after grinding, the blade can be reinserted in the axial direction, for example in a position which is displaced outwards by a tooth width. As soon as the cutter head is set into fast rotation, the centrifugal wedge is tightened by centrifugal force. The blade is then clamped in a fixed and precise manner. Since the centrifugal wedge is configured to be self-locking, it remains clamped even after the cutter head has stopped. An advantage of the described cutter head is that the screws do not have to be undone when the blade is changed. However, a disadvantage is that the blade can only be removed in an axial direction from the groove. This means that first of all, adjacent cutter heads have to be removed from the tool spindle before the blade can be removed.
In the case of cutter heads with conventional blade holders without centrifugal wedges, when wide blades are used, a plurality of screws is generally required to fix the blades to the cutter head. This necessitates more effort during a change of blade. A further problem with conventional cutter heads of this type is that the pressure bodies are fastened by screws in a groove in the cutter head against the centrifugal force which arises during rotation. With high rotational speeds, the blade can move slightly due to the effective centrifugal forces, which adversely affects the woodworking accuracy and results in relatively high tolerances.
It is therefore an advantage of the present invention to provide a tool head, in particular a cutter head for a woodworking machine tool, and a method in which the tool, respectively the blade can be inserted and removed in a radial direction. A further advantage is to provide a tool head for which, during a change of tool or blade, it is no longer necessary to previously dismantle tool heads which are adjacent to the tool head. A further advantage is to propose a tool head, for which the effort in changing tools is minimised. A further advantage is that during a tool change, the new tool is precisely adjusted in a radial direction and in an axial direction.
The aforementioned advantages are realised according to the invention by the features of the claims. Advantageous developments are defined in the subclaims.
The invention relates to a tool head, in particular to a cutter head for a woodworking machine, having a cylindrical, conical or profiled main part for the rotating machining of a workpiece. The tool head has at least two tool mounts, evenly distributed over its circumference, for receiving a flat tool, in particular a cutting insert. The tool mounts respectively have grooves which taper in the radial direction and in which a respective cutting insert can be clamped between a first side wall of the groove and a closure element which serves as a pressure jaw. A centrifugal wedge which can be inserted into the groove can press the closure element against the cutting insert and can fix said cutting insert in the tool mount. Provided between the cutting insert and the first side wall is a first positive locking connection which fixes the cutting insert in the radial direction.
According to the invention, a second positive locking connection is provided between the closure element and the centrifugal wedge. This arrangement of the positive locking connections, namely between the cutting insert and the tool head on the one hand and between the closure element and the centrifugal wedge on the other has the advantage that, during clamping, a relative movement between closure element and cutting insert is possible, because there is no positive locking connection between the cutting insert and the closure element. The proposed arrangement of the positive locking connections also means that the cutting insert can be inserted into the groove in the radial direction.
The centrifugal wedge advantageously has a hole with an internal thread, into which a clamping screw with an external thread can be inserted. In this respect, by turning the clamping screw in a first direction, the centrifugal wedge can be moved into the clamping position and by turning the clamping screw in a second, opposite direction, the centrifugal wedge can be moved into the tool change position. Compared to the prior art, this tool holder has the advantage that the centrifugal wedge is pretensioned radially outwards even when the tool is clamped. This has the advantage that the centrifugal wedge and the cutting insert no longer move as the tool head starts to rotate. According to an advantageous embodiment, the clamping screw is a threaded pin, on the one end face of which is formed an engagement means, for example a hexagon socket or a Torx screw profile, and on the second end face of which is formed a cylindrical screw head. When the centrifugal wedge is inserted into the tool mount, the cylindrical screw head rests against the base of the groove which acts as a counter bearing. It is conceivable for the screw head to have on its end face a locking extension which can engage with clearance in a corresponding blind hole in the base of the groove. This has the advantage that the centrifugal wedge cannot move in the groove. Moreover, the blind hole and locking extension are configured so that it is possible to radially pre-assemble the clamping screw.
A screw hole with an internal thread is advantageously provided in the base of the groove, and the shank of the clamping screw has two threaded portions with opposed screw threads. This has the advantage that with an appropriate choice of the rotational direction of the screw thread, the centrifugal wedge moves away from the base of the groove when the clamping screw is screwed into the screw hole. According to another embodiment, the clamping screw can be inserted rotatably but immovably in the axial direction into the hole in the centrifugal wedge. In this way as well, the centrifugal wedge can be pressed against the closure element by turning the clamping screw.
The closure element is expediently received, respectively fixed in the tool mount without screws. This has the advantage that it can be quickly inserted or removed. This facilitates the tool change.
According to one embodiment, either the closure element or the centrifugal wedge is fitted with at least one magnet. The provision of at least one magnet has the advantage that the cutting insert which is advantageously produced from a weakly magnetisable material is held on the closure element. This has the advantage that the cutting insert is drawn onto the closure element in the tool change position. Since the cutting insert is also tilted when the centrifugal wedge is released, the cutting insert can be effectively grasped using fingers.
The at least one magnet is inserted into an opening in the closure element so that it is flush with the surface of the closure element. This has the advantage that the cutting insert can rest flatly on the closure element. For reasons of symmetry, at least two spaced-apart openings are expediently provided in the closure element, magnets being inserted flush into said openings.
The one or more openings are advantageously provided in the lower region of the closure element at a short distance from the base of the closure element, particularly in the lower third of the closure element. However, other positions are equally possible, subject to the dimensions of the cutting insert.
According to a particularly advantageous embodiment, a pressure element or spring element is provided which is positioned between, respectively in the groove, so that it acts on the cutting insert in the radial direction when the tool is clamped. The pressure element is advantageously elastically or resiliently deformable and is produced, for example from an elastically deformable plastics or a spring element, for example a coil spring. The pressure element or spring element is located where the lower edge of the cutting insert rests on a shoulder of the tool mount, so that the pressure element or spring element can cooperate with the lower edge of the cutting insert. The pressure element or spring element can be inserted into the groove or arranged on the closure element.
An expedient embodiment provides that the pressure element or spring element is provided or arranged on the closure element. In this respect, it can be arranged under the magnets, i.e. closer to the base of the closure element, seen in the longitudinal direction. The pressure element or spring element can be configured as a plastics positioning nub which projects from the surface. The positioning nub can be inserted, for example into a hole in the closure element.
According to another embodiment, the pressure element or spring element is a spring which is simultaneously used for the lateral and radial positioning of the blade and for pressing the closure element onto the jaws of the centrifugal wedge.
The centrifugal wedge advantageously has a front wedge surface which is oriented towards the first side wall of the groove, and a rear surface which is opposite the wedge surface, is oriented towards the second side wall of the groove and is at an acute angle to the front wedge surface. The wedge surface has a channel-shaped recess which runs in the axial direction. The recess has the advantage that the contact pressure is concentrated on the regions of the centrifugal wedge which are adjacent to the recess.
An elevation which extends in the axial direction is advantageously provided on the wedge surface. The elevation, for example an elongate bead can provide a positive locking with the closure element.
Expediently provided above the recess is a first pressure surface and provided below the recess is a second pressure surface of a minimum width of at least 1 mm, at least 2 mm, or at least 3 mm.
The first side wall of the groove includes an angle of between 0 and 40 degrees, between 15 and 35 degrees or between 20 and 30 degrees with a radial emanating from the centre of the tool head.
The base of the centrifugal wedge is advantageously configured with a step which extends parallel to the longitudinal axis of the hole, thereby providing a first base surface which adjoins the front wedge surface and a second base surface which adjoins the rear surface. In this respect, the second base surface includes an angle of >90 degrees, preferably between 90.1 and 95 degrees or between 90.5 and 94 degrees with the rear surface. This physical formation of the centrifugal wedge has the advantage that a tilting movement of the centrifugal wedge can be caused on releasing the tool holder.
A centring pin can be introduced in the first groove wall (for example press fit), for laterally centring the cutting insert and optionally the closure element.
According to a particularly advantageous embodiment, provided between the centrifugal wedge and the closure element is a third positive locking connection for laterally centring the closure element. This is a particularly advantageous embodiment which, together with the second positive locking connection, allows the radial and axial adjustment of the cutting insert.
The present invention also provides a cutting insert for a tool head of a woodworking machine, in particular for a tool head according to any one of claims 1 to 20, having a cutting insert, a cutting edge, formed on a first side (front of the blade) of the cutting insert, and a positioning channel which is provided on the second side of the cutting insert opposite the cutting edge. This cutting insert according to the invention is distinguished in that the edge of the cutting insert diagonally opposite the cutting edge has a functional surface in the form of a bevel or a rounding, the depth of which is at least 15% of the thickness of the cutting insert. This cutting insert has the advantage that it can be positively fixed directly in the tool body. The bevel is advantageously 0.6 mm. The advantage of this bevel which is significantly larger compared to known cutting inserts is that an elastically deformable pressure element can expand through the increased free space between the groove wall and cutting insert when the centrifugal wedge is clamped. Thus, the larger bevel is significant in connection with the correct radial positioning of the cutting insert. In addition, this functional surface also has a safety relevance, since without it, the brittle cutting inserts could break while they are being clamped and could fly off during operation.
Only a single positioning channel is provided, the lower edge of which is located at a distance of <10 mm or <8 mm from the base surface of the cutting inserts.
It is also significant that the positioning channel is located inside a clamping region. This clamping region is on the one hand restricted in depth by the shoulder of the first groove wall and on the other hand is restricted in height by the apex of the top surface of the centrifugal wedge, and of the first pressure surface of the centrifugal wedge.
The cutting insert advantageously has at least one U-shaped recess for lateral positioning. However, it is also possible for the cutting insert not to have a U-shaped recess. In this case, the lateral positioning can be performed, for example by two lateral positioning elements, between which the cutting insert is arranged.
The present invention also provides a method for inserting and clamping a tool in a mount of a tool head according to the preamble of claim 27, in which method the closure element is held positively by the centrifugal wedge after being inserted into the tool mount.
According to another independent aspect of the invention, the closure element is held in the change position by the centrifugal wedge, and the tool is held in the clamping position by a positive locking connection with a side wall.
According to a further independent aspect of the invention, the centrifugal wedge is moved into the clamping position and into the change position by means of a clamping screw. The advantages associated with the previously mentioned variants of the method have already been discussed above in the discussion of the tool head according to the invention.
The cutting insert is advantageously clamped in the centrifugal force direction by a clamping screw which engages on the centrifugal wedge. This has the advantage that the centrifugal wedge no longer moves due to the centrifugal forces which are effective during operation of the rotating tool head. A consequence of this is a greater precision during the machining of the workpieces.
Before the cutting insert reaches its final clamping position, it is pressed outwards in the radial direction against a stop. This has the advantage that the cutting insert is accurately positioned in the tool mount and cannot slip during operation.
Before reaching the final position, the tool is advantageously positioned, respectively strikes against a stop ledge by means of a resilient element.
In the change position, the cutting insert is advantageously drawn in a releasable manner onto the closure element. This is expediently performed by means of a magnet which can be arranged on the closure element or on the centrifugal wedge.
According to a particularly advantageous variant of the method, the centrifugal wedge is released by means of the clamping screw. Thus, in contrast to the prior art, the centrifugal wedge can be released without using a hammer.
The closure element is advantageously held positively by the centrifugal wedge in the tool change position.
The cutting insert is advantageously clamped on the stop and in the flight direction.
The present invention also relates to a tool head for a woodworking machine, having a cylindrical, conical or profiled main part which has at least two tool mounts which are distributed evenly over its circumference, for receiving a cutting insert, a single tool mount being formed by a groove which is open in the radial direction. The groove is formed by a first side wall and by a second side wall opposite the first side wall and at a distance therefrom. A centrifugal wedge can be arranged in the groove in order to clamp a cutting insert which is arranged between the first side wall and the centrifugal wedge, in that the centrifugal wedge is moved radially outwards by a clamping screw.
This tool head is further characterised in that provided in the tool mount is a spring element which radially presses a cutting insert, introduced into the tool mount, against a stop. The tool head configured thus has the great advantage that during clamping, the tool is radially positioned automatically in that it is automatically moved radially outwards by the spring means and is brought against a projection provided on the tool. This measure provides an exact positioning of the cutting inserts in the tool mount without any additional effort and expense.
The spring element can be a spring or an elastically deformable plastics part or metal part which engages in a recess in the cutting insert or engages against the base of the blade.
The invention also provides a method for positioning a cutting insert in a tool mount of a tool head, in which method a cutting insert, introduced into the tool mount, is pressed against a stop by means of a spring element which is provided in the tool mount and is oriented accordingly, in that the spring element exerts a radially outwardly effective force on the cutting insert. In this respect, it is significant that positioning takes place automatically when the tool is clamped. The spring element can ensure the radial, the lateral or the lateral and radial positioning.
Embodiments of the invention will now be described in more detail with reference to the following figures, in which:
As mentioned above, the groove 19 tapers outwards in a wedge shape in the radial direction, i.e. the first groove wall 27 and a second groove wall 31 opposite the first groove wall 27 are inclined with respect to one another. The centrifugal wedge 23 is received in the groove 19. The configuration of the centrifugal wedge 23 and of the groove 19 is such that the centrifugal wedge can be inserted into the groove 19 in the radial direction when the closure element 25 is not present. However, it is also conceivable that the configuration of the centrifugal wedge 23 and of the groove 19 is such that only a lateral insertion is possible. Both embodiments are equally possible within the scope of the present invention.
The centrifugal wedge 23 has a front wedge surface 33 which rests against the closure element 25, and a rear surface 35 which rests in a planar manner on the second groove wall 31. If the closure element is not provided, the front wedge surface 33 rests directly on the cutting insert. The front wedge surface 33 is interrupted by a recess 37 which extends in the longitudinal direction of the centrifugal wedge 23, so that a first contact surface 39 is present above the recess 37 and a second contact surface 41 is present below the recess. The second contact surface 41 has an elevation 43 in the form of a bead which extends in the longitudinal direction and allows a positive locking connection with a corresponding, complementarily formed recess 47 in the closure element 25.
The base of the centrifugal wedge 23 is step-shaped so that a first base surface 49 is present adjoining the front wedge surface 33 and a second base surface 51 is present adjoining the rear surface 35. The first and second base surfaces 49, 51 are separated by a step 53 which extends substantially parallel to the rear surface 35. In this respect, the second base surface 51 includes an angle of 90 degrees or more, or between 91 and 93 degrees, with the rear surface 35. This can cause the centrifugal wedge 23 to tilt in the change position, as will be explained in more detail further below.
In order to reduce weight, one or more spaced-apart slots 55 can be provided in the centrifugal wedge 23. Located between the slots 55 is a screw hole 57 with a longitudinal axis 59, which screw hole extends from the top surface 61 to the second base surface 51. The longitudinal axis 59 of the screw hole 57 extends substantially parallel to the rear surface 35. The screw hole 57 has an internal thread 63 to receive a rear threaded portion 99 of the screw 29 (
The base of the groove is also step-shaped analogously to the base surface 49, 51 of the centrifugal wedge 23. It comprises a first groove base surface 65 which corresponds to the second base surface 51 of the centrifugal wedge 23, and a second groove base surface 67 which corresponds to the first base surface 49. A screw hole 60 with an internal thread 70 is provided in the first groove base surface 65. The screw hole 69 is collinear with the longitudinal axis 59, so that by turning the screw 29, the centrifugal wedge 23 can be moved from an upper clamping position in which the closure element 25 and the cutting insert 15 are pressed firmly against the first groove wall 27, into a lower tool change position in which the cutting insert 15 can be removed in the radial direction.
As mentioned above, while the base surface 51 includes an angle of 90 degrees with the rear surface 35, the angle between the first groove base surface 65 and the rear surface 31 is approximately 90 degrees. If the base surface 51 includes an angle of >90 degrees with the rear surface 35, when the tool mount is opened, the second base surface 51 of the centrifugal wedge 23 near the step 53 thus firstly comes into contact with the first groove base surface 65. Consequently, on reaching the tool change position, a transverse force acts on the centrifugal wedge 23, which transverse force causes the centrifugal wedge 23 to tilt due to the existing tolerances of the screw thread (
A distinctive feature of the closure element 25 is that at least one, but or two or more magnets 69 are provided in the lower region (
Two elastically deformable plastics nubs 73, in particular those of an elastomeric material, are provided in the closure element 25 at a distance from one another just above the recess 47. These nubs can be introduced into corresponding holes 75 in the closure element 25. The purpose of the nubs 73 is to push the cutting insert 15 upwards during the clamping procedure. The mode of operation of the nubs 73 is described in more detail further below.
A U-shaped recess 77 in the centre of the rear fixing portion is provided for the lateral centring of the closure element 25 in the groove 19. Engaging in this recess 77 in the clamping position is an axially adjustable centring pin 79 which is received in a pinhole 81 in the body of the tool head (
A single channel 83 is provided in the first groove wall 27 just above the pinhole 81. A stop ledge 85 is received positively in this channel 83. The channel 83 and the corresponding stop ledge 85 can be four-sided or polygonal or round in cross section. In the clamping position, the stop ledge 85 cooperates with a groove 87 in the cutting insert 15 for accurate positioning (
The cutting insert 15 which, according to
As can be seen in
Within the context of the present invention, those portions of the tool mount which cooperate in the tool mounting are referred to as groove 19. According thereto, the groove 19 has first and second groove walls 27 and 31 which differ in length.
The rear wall portion 93 of the first groove wall 27 above the shoulder 91 can be slightly inclined inwards relative to the front wall portion 95 and can include an angle of up to 5 degrees (see
The screw 29 for clamping and releasing the centrifugal wedge 23 is configured as a threaded pin having a front and a rear threaded portion 97 and 99 respectively (
A further modified embodiment of a centrifugal wedge 23 has on the wedge surface 33 a centring element 105 in the form of a centring nub which projects out of the wedge surface 33 (
The embodiment according to
The tool head 11d according to
A modified clamping mechanism is shown in the case of the tool head 11e according to
The tool head according to the invention is used as follows: to introduce a new cutting insert into the tool head according to
The tool head according to the invention is used in particular for machining wood, plastics and similar materials, for which the method when machining and removing chips or particles is similar. Similar materials are, for example cork, bone, plastics, light metal alloys, wood materials such as chipboard, fibreboard, plywood etc. Cutting inserts having a straight, curved or profiled cutting edge are used as the tools. The cutting inserts consist of flat blades which are between approximately 1 mm and 3 mm thick. During operation, the cutter head is arranged in a rotatably fixed manner on a spindle of a woodworking machine, it being possible for further cutter heads to be attached to the spindle in a directly adjacent position. According to one aspect of the invention, the centrifugal wedge can be adjusted (clamped and released) by a single screw for all scopes of application. In this respect, the cutting insert is pressed onto the stop ledge 85 in the flight direction during clamping, so that the cutting insert cannot move any further as the tool head rotates.
In the above description, the embodiments are respectively described by way of example on the basis of a tool head which is circular cylindrical in cross section and in which the tool is received in an axial groove (axially parallel to the rotational axis). However, within the scope of the invention, the tool mount or respectively groove can also extend at an angle to the rotational axis (for example, conical tool head). Thus, the groove can be at 3 spatial angles relative to the rotational axis and can thereby define a rake angle, an offset angle and an axis angle.
| Number | Date | Country | Kind |
|---|---|---|---|
| 569/2014 | Apr 2014 | CH | national |
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/CH2015/000055 | 4/14/2015 | WO | 00 |
