Cutting knife for chip-removing cutting tools with breaking notch

A cutting knife for difficult-to-manipulate, chip-removing cutting tools, that is replaceably held in a knife window of a rotary-driven tool shaft of a base body, in which at least one knife holder that is connected to the cutting knife over a predetermined breaking point, and that assists with manipulation, is attached to the cutting knife, and is broken away for the tool shaft to be put to use.

The invention relates to a cutting knife for chip-removing cutting tools that are hard to manipulate by hand, according to the generic term of patent claim1.

Cutting knives for chip-removing cutting tools are used in varied embodiments.

One possible embodiment is shown by the state of the art in the form of our own patent application DE 10 2004 054 989. Such cutting knives are especially used for deburring tools, however also for counter-boring tools, routing tools and milling tools. That revelation shall fully apply to the present invention.

Such cutting knives are smaller than a specific minimum size of, for example, 10 mm, such that their manipulation is made difficult, and there are problems replacing such a relatively small, difficult-to-handle cutting knife in its corresponding tool.

In other applications, it is not exclusively a matter of small knives whose small size makes them difficult to handle, but also problematic assembly relationships, in which a comparatively easily handled knife is to be installed in a hidden or difficult-to-access place in the tool.

In all of these cases, there are problems installing the cutting knife in the desired, correct position in the tool holder itself.

The underlying task of this invention, therefore, is to further develop a cutting knife for chip-removing cutting tools of the type mentioned at the beginning, such that it is easy to manipulate or that it is easy to install in a tool that is difficult to access.

As a solution to the problem posed, the invention is characterized by the technical theory for claim1.

A significant characteristic of the present invention is that the cutting knife is attached through a predetermined breaking point to at least one knife holder as a manipulation aid.

With the given technical teaching, there is the significant advantage that for the first time it is now possible to manipulate well very small cutting knives of lengths, for example, from 1.9 mm to 5 mm, because according to the invention at a certain place on the cutting knife there is a knife holder that assists manipulation, and that this knife holder is attached over a predetermined breaking point to the knife.

Installing such a cutting knife that is attached to a knife holder according to the invention as a manipulation aid is done in such a way that the cutting knife is inserted with the knife holder that is still mounted through the predetermined breaking point into an opening in the cutting or countersinking tool and is there anchored in the correct position by the mechanism in the cutting or countersinking tool. After the anchoring in the correct position, a short press on the knife holder (which serves as a manipulation aid) stresses the predetermined breaking point by bending it until it breaks. This generally occurs through a short bending of the knife holder, such that the predetermined breaking point then lies inside the tool slot and does not project from the tool. This provides the advantage that the knife holder is broken off only once the knife has been installed in the tool firmly and in the correct position.

Of course, within the framework of the present invention, it remains open where the knife holder sits over the predetermined breaking point on the cutting knife. This can occur at various points.

In a first embodiment it is provided that the knife holder with the predetermined breaking point placed upon it sets on the rear part of the cutting knife, i.e., on the part that is formed opposite the floating radius and the cutting edge.

In another embodiment it can, however, be provided that the knife holder sits above the predetermined breaking point on the front floating radius of the knife, i.e., sits directly on the knife head, and in a third embodiment it can be provided that the knife holder sits on the base of the cutting knife.

In all applications, it is important that it first be provided that the knife is attached to at least one manipulation aid that is attached to a predetermined breaking point with the knife itself.

It is to be understood only as an example, that the knife holder (manipulation aid) be attached to the floating radius, i.e., to the head of the cutting knife itself. For other knives, such as milling cutters or similar knives, such a floating radius can be omitted, and it is important only that the knife holder (manipulation aid)—in this execution example—grip directly to the cutting part of the cutting knife itself and not to another part or to another surface of this cutting knife.

The invention is also not limited to the assembly of a knife holder that sits on one side of the tool. In another execution it can be provided that two knife holders be located on the tool (e.g., the cutting knife), of which each is attached to the tool over a predetermined breaking point. Such an execution is especially suitable if it is provided that the cutting knife be slid in by gripping to the rear knife holder in the insertion direction in the recess on the tool holder. The knife holder running in the insertion direction goes through the insertion opening in the tool holder and emerges on the other side of the tool holder. Thus the cutting knife that is installed in the opening on the tool holder and is now blocked is equipped with two knife holders that lie opposite one another and are preferentially aligned to each other.

To complete the installation, then, one and then the other knife holder is broken off. Such a dual assembly of knife holders is an advantage with especially small tools that are difficult to manipulate.

The invention is not, incidentally, a knife that can be slid radially into a knife window of a tool holder. It makes no difference in which direction the knife can be slid. There are also applications that indicate a knife that is immovably attached in a knife holder but is nonetheless replaceable. In such an application the knife holder itself is formed to be adjustable or pivotable but holds an immovable knife. Such applications should also be considered a part of the invention.

A single, replaceable knife is described for the purpose of simplified description. However, the invention is not limited to this. Any number of knives or other tool inserts can be equipped with the breakaway handle according to the invention.

The object of this invention arises not only from the object of the individual patent claims, but also from the combination of the individual patent claims together.

All of the documentation, including the summary of disclosed data and characteristics, especially the spatial design depicted in the drawings, are claimed to have significance as inventions, as long as they are new individually or in combination in relation to the state of the art.

FIG. 1briefly explains the operation of a deburring knife, although that is not significant to the present invention. Significant is only that a relatively small knife9in a knife window14of a tool shaft2of a base body1is adjustably held.

Here the knife9is installed in the knife window4and is held by a shaft3that is prestressed by a spring, whereby the shaft3is prestressed by the pressure spring4in the direction of its longitudinal extension. The spring4is connected at its rear end to a threaded pin6, at which the pressure of the pressure spring4can be set.

When the clamping screw5is loosened, the entire tool shaft2can be pulled out of the base body1.

Furthermore, an eccentric tappet7is in place, which can be activated for retracting the shaft3, so that it disengages from the indentation17on the knife9.

In this way the knife can be replaced very easily. If this replacement is undertaken, the knife falls out of the knife window14in the direction of the arrow18and must be replaced with a new knife. The replacement process with the help of the new knife and the knife holder10attached to it according to the invention is explained byFIG. 1and by the figures thereafter.

In order to install a new knife into the knife window14, it is provided that, according toFIGS. 4 to 6, on the rear part of the knife9the knife holder10is attached, by which the connection is broken by means of a predetermined breaking point13.

Now the knife9with the knife holder10fastened on the back according toFIG. 1is pressed upward in the direction of the arrow18onto the knife window14, and the knife is now slid into the knife window14. The shaft3is still retracted. However, it can also be provided that the shaft already protrudes under prestress from the pressure spring4into the knife window14. In this position, the knife is pressed inward from the arrow direction18described above downward into the knife window14until the tip of the shaft3engages into the indentation17on the knife9. The knife is now in its proper position. If the knife holder10is now bent vertically in the paper plane ofFIG. 1with a short jolt, it breaks off in the area of the predetermined breaking point13and leaves the knife behind installed in its proper place in the tool shaft2.

Important here is that the position of the predetermined breaking point be selected in such a way that the rest of the predetermined breaking point13that remains on the knife9installed in the tool shaft2does not protrude obtrusively from the outer circumference of the tool shaft2.

FIG. 1shows further that the knife can be installed not only from above in the direction of the arrow18, but also opposite the drawn arrow direction18. Thus it can be slid into the knife window from the underside in the opposite direction from the arrow18.

Referring toFIG. 3, two knife holders10and10acan be located on the cutting knife9, each of which is attached to the cutting knife9over a predetermined breaking point. The two knife holders10and10alie opposite one another and are preferably aligned to each other. The cutting knife9can be installed by gripping the rear knife holder10and inserting the forward knife holder10ainto and through the recess14in the tool shaft2in the insertion direction18. The forward knife holder10aemerges on the other side of the tool shaft2and can be gripped by a user to further manipulate the cutting knife9. Once the cutting knife9is properly positioned the two knife holders10and10aare broken off.

It his further pointed out that here only the replacement of a single knife is drawn, whereas there are of course tools in which a variety of different knives must be replaced, which is possible with the same procedure. The procedure consists mainly of bringing the cutting knife into its proper position in the tool with the help of the knife holder as a manipulation aid, in order then to break away the knife holder10.

FIG. 4shows that the knife holder10is attached to the sides opposite the cutting edges11and floating radius12of the knife9over the predetermined breaking point13.

It can also be provided in another embodiment that the knife holder10is connected to the knife9in the area of the floating radius12with a predetermined breaking point13, or in a further embodiment that the knife holder10is connected to the base16of the knife9over a predetermined breaking point.

Depending on the situation of use, it can also, of course, be provided that the knife holder10is connected to the knife over a predetermined breaking point with a laterally abutting face19.

FIGS. 3 and 5show that the predetermined breaking point13is achieved through a material-weakening constriction in the metal material of the cutting knife. It is preferred that the knife holder10and the cutting knife consist of the same material. However, it can be provided that the knife9is hardened, while, for example, the knife holder10is not, because it is excluded from the hardening process for the purpose of cost savings.

In another embodiment of the present invention it is specified that the predetermined breaking point13not be formed by a constriction according toFIGS. 5 and 4, but by another material-weakening permeation in the area of the predetermined breaking point. Such a permeation can be a material-weakening drilled hole13a, e.g., that penetrates the joint centrically or acentrically between the knife holder10and the knife9, to create at this place a material-weakening cross-section that then later forms the predetermined breaking point13, as shown inFIG. 3.

FIG. 7additionally shows that the knife window14preferentially has a key face15in order to ensure that the knife9can be slid only into a specific, correct position in the knife window14and that other positions are thereby not possible. This ensures that even small knives of approximately 2 mm can be slid into the proper position in the knife window14without visual inspection, after which, according toFIG. 1, the knife holder10is broken away and the knife9is then held in its proper position in the tool shaft2and is ready for work.

All aforementioned mounting possibilities (cutting head, rear side, laterally to the rear—right or left) for the knife holder to the body of the cutting knife, whether alone or in combination, are claimed as significant to the invention.

KEY TO DRAWINGS