EP0286837A1 - Cutting unit - Google Patents

Abstract

The invention relates to a knife insert (1) for tools with an oscillating head, preferably of the type used for separating rubber or adhesive beads on windshields, with a cutting surface (2) which is delimited by one or more cutting edges. In order to consume less expensive material in the manufacture of such a knife and to considerably reduce the stroke movements of the shaft when driven by a tool which carries out oscillatory rotary movements, the invention proposes that the knife (1) be perpendicular to its cutting surface (2) L is angled in a shape, the cutting surface forming a first L-leg, and that the second L-leg (3), which extends essentially perpendicularly from the cutting surface, has a connecting element (4) for connection to an actuating tool.

Description

The invention relates to a knife insert for tools with an oscillating head, preferably of the type used for the separation of rubber or adhesive beads on windshields, with a cutting surface which is delimited by one or more cutting edges.

Knives of this type generally have a flat, possibly slightly spherical cutting surface and, in operation, are attached to an oscillating head which carries out very rapidly oscillating rotary movements over a small angular range. The knife is attached to a spindle serving as a tool holder, which in turn is attached to the head of the tool or drive assembly so as to be rotatable about the small angular range mentioned.

The previously known knives are either Z-shaped or U-shaped in the side view, one leg of the U or the Z forming the cutting surface or cutting edge, while the knife was fastened to the tool carrier or the spindle with the other leg. The intermediate piece connecting the two legs and extending essentially perpendicular to them serves above all to be able to use the knife even in inaccessible places, such as for car windscreens between the support surface in the window frame and the windshield itself.

These known embodiments have several disadvantages in common. In order to achieve sufficient stability, the known knives have been made in one piece from the same material, since the part of the knife which extends from the cutting edge to the tool carrier and which is referred to below as the shank is narrow and thin in order to avoid the aforementioned inaccessible parts To be able to safely reach places with the knife edge.

However, since the knives are made of a specially alloyed material exist, which is tough, resilient and difficult to work, the production of the connection area of the shaft was correspondingly complex and expensive and it was generally used for the production of the shaft much more material than for the production of the cutting part of the knife. On the other hand, the material properties mentioned, which are important for the cutting edge, are only of minor importance for the shaft. Only a certain strength with small dimensions is required because the knife is exposed to considerable loads during operation.

Furthermore, in the known knives, the axis of rotation is far from the shaft part, which extends perpendicularly from the cutting surface. This part also performs the oscillatory rotary movements with a stroke of a few mm. In the case of windshields which are closely fitted into the vehicle frame, when operating such a tool, this shaft part lies exactly between the edge of the windshield and the vehicle frame. The vehicle frame and / or the windshield can therefore be damaged by the oscillatory rotary movements of this shaft part. From this point of view, it would make more sense if this shaft part is arranged near the axis of rotation or if the axis of rotation even runs through this shaft part.

The invention is therefore based on the object of providing a knife with the features mentioned at the beginning, for the manufacture of which less expensive material is consumed and in which the stroke movements of the shaft are considerably reduced.

This object is achieved in that the knife is angled L-shaped perpendicular to its cutting surface, the cutting surface forming a first L-leg, and in that the second L-leg, which extends essentially vertically from the cutting surface, is a connecting element for connection to a Has actuating tool.

The latter connecting element, which extends practically in the direction of the second L-leg, can be made of a different, cheaper material than the knife itself. Only the cutting edge itself and the angled second L-leg are still tough and heavy material to be machined.

Since the connecting element is attached directly to the second L-leg and since the connecting element is usually mounted concentrically to the axis of rotation of the spindle-shaped tool carrier, the second L-leg itself is also arranged in the immediate vicinity of the axis of rotation and accordingly only performs very small lifting movements during operation .

It is provided according to the invention that the connecting element is welded to the second L-leg. This can preferably be done by friction welding.

Such a connection is very durable and can be made in a matter of seconds. In particular, a material can be selected for the connecting element which is much easier to process than the material from which the knife edge and knife shaft are made, and which can nevertheless be easily welded to the knife shaft.

The invention provides that the connecting element is a part with a polygonal cross section. Such a part can be easily non-positively and positively attached to a corresponding receptacle on the tool carrier or the spindle of the device which drives the knife.

A four- or six-sided shape of the connecting element is preferred. Square and hexagonal shapes are used as standard for power transmission, so that appropriately prepared raw material can be procured and processed at low prices. To achieve the welded connection between the connecting element and the shaft or the second L-leg of the knife with the greatest possible strength testify, it is advantageous if the connecting element and the shaft lie on top of one another over a large area. This is easy to achieve with square material. In the case of hexagonal or polygonal material, one of the surfaces of the connecting element in the connecting region with the shaft can optionally be made larger, so that the usual, regular cross-sectional shape no longer results, but rather the connecting element at least in the region in which it welds to the shaft of the knife is asymmetrically shaped.

In addition to the square or hexagonal shape mentioned, the octagonal or twelve-sided shape or a wave shape of the surface of the connecting element have proven to be expedient.

The polygonal elements need not be regular polygonal shapes. In particular, a square can also have two narrow and two wide sides, that is to say the cross section of a sheet metal strip. If necessary, the second L-leg of the knife insert itself can also form the connecting element 4. With a suitably chosen width of such a square connecting element in the form of a strip or a plate, this can also be inserted into receptacles of a spindle, which is otherwise provided for regular polygonal shapes, the two narrow sides of the connecting element respectively resting in opposite corners of the polygonal receptacle.

Instead of the aforementioned forms, in which the connecting element is simply and positively and positively inserted into a correspondingly shaped receiving opening of the tool carrier or the spindle, in another embodiment of the invention, a screw connection can also be provided between the connecting element and the tool carrier. In particular, the connecting element itself can be designed as a screw which can be screwed into a corresponding thread of the tool carrier or the spindle.

The symmetrical polygonal connectors have the advantage part that the knife insert rotated by fixed angular amounts can be inserted into the spindle. With a regular twelve-sided connection, for example, this angle is 30 °. In the case of a screw connection, the orientation of the knife is generally not so well defined, but can optionally be set as desired using additional holder elements such as lock nuts or the like.

In a preferred embodiment of the invention it is provided that the connecting element has a bore or a groove which extends substantially perpendicular to the direction of insertion of the connecting element into the tool carrier. A groove can, for example, be arranged at a fixed axial height along the entire circumference of the connecting element, so that an axial holding of the connecting element by parts engaging in the groove is independent of the orientation in which the knife insert or the connecting element is inserted into the spindle .

According to the invention it is provided that a locking pin to be guided through a suitable bore in the tool carrier can be inserted into the groove or bore.

After the connecting element has been inserted into a corresponding receptacle of the spindle or, if necessary, also screwed in, the knife insert is secured against axial displacement by a locking pin being passed through a bore in the tool carrier, which is at the same axial height as the groove of the inserted connecting element. The bore in the tool carrier and the groove or a corresponding bore in the connecting element are arranged relative to one another such that the locking pin also engages in the groove or the bore of the connecting element. The locking pin can in turn be secured against slipping out of the bore by spring elements. The axial securing of the knife is particularly necessary because the drive elements for the knife perform up to 25,000 strokes per minute and a knife slipping out could be thrown at high speed and could injure people.

It has proven to be expedient if, in the present invention, the connecting element is attached to the second L-leg at a distance from the cutting surface.

The connecting element, which, for example as a square or hexagonal pin, has a significantly larger cross section than the knife shank or the second L-leg, cannot be easily fitted into narrow gaps or slots, e.g. insert between the windshield and the body, so that it is advantageous if the connecting element is attached to the shaft at a distance from the cutting surface, so that the remaining free shaft part allows the knife to be inserted into the inaccessible areas mentioned.

An embodiment is preferred in which the connecting element tapers in the direction of the cutting surface. As before, the connecting element can additionally be attached to the shaft at a distance from the cutting surface or not. The tapered part then allows a better insertion of the knife and the knife shaft and possibly also parts of the connecting element into the inaccessible areas mentioned.

Furthermore, a connecting element is preferred according to the invention, which can be positively inserted into an adapter provided with a screw connection.

The plug-in knife inserts can also be attached to a conventional spindle with a screw thread.

The new, plug-in knife inserts therefore do not require the replacement of entire drive units, but the conventional drive units can continue to be used, with either only the spindle being replaced or the one being replaced imagined adapter is screwed to the conventional spindle using a clamping screw.

• Figur 1 einen Messereinsatz mit Verbindungselement in der Seitenansicht,
• Figur 2a das Messer aus Figur 1 in der Draufsicht von oben,
• Figuren 2b-e je eine Ansicht entsprechend Figur 2a für ver­schiedene Typen von Messereinsätzen,
• Figur 3 eine Seitenansicht auf eine Spindel, in welche Mes­sereinsätze einsteckbar sind,
• Figur 4 eine Ansicht der Spindel nach Figur 3 von unten,
• Figur 5 eine Ansicht entsprechend Figur 4 mit in die Spindel eingestecktem Sicherungsstift,
• Figur 6 einen Adapter zum Anbringen eines L-förmigen Messers an eine Spindel und
• Figur 7 die Ansicht auf den Adapter nach Figur 6 von unten.

Further advantages, features and possible uses of the present invention will become clear from the following description of a preferred embodiment and the associated figures. Show it:

• FIG. 1 is a side view of a knife insert with connecting element,
• FIG. 2a shows the knife from FIG. 1 in a top view from above,
• FIGS. 2b-e each show a view corresponding to FIG. 2a for different types of knife inserts,
• FIG. 3 shows a side view of a spindle into which knife inserts can be inserted,
• FIG. 4 shows a view of the spindle according to FIG. 3 from below,
• FIG. 5 shows a view corresponding to FIG. 4 with the locking pin inserted into the spindle,
• Figure 6 shows an adapter for attaching an L-shaped knife to a spindle and
• Figure 7 shows the view of the adapter of Figure 6 from below.

1 shows a knife insert 1 with a cutting surface 2 and a shaft 3 to which a connecting element 4 is welded. The connecting element 4 is mounted at a distance from the cutting surface 2 on the shaft 3 and bevelled at its lower left corner, so that it tapers in the direction of the cutting surface 2. In this way, additional space is gained in order to be able to work with the knife in corner areas and similar places that are difficult to access.

The connecting element 4 has in its upper third a circumferential, semi-cylindrical groove 5 and, moreover, has the shape of a square rod, as can best be seen in FIG. 2a. In Figure 2a it can also be seen that the connecting element 4 is not arranged exactly above the cutting surface 2, but is slightly offset. The axis of rotation around which the Knife executes torsional vibrations in operation, essentially coincides with the axis of symmetry 8 of the square rod. By a suitable choice of the dimension of the chamfer of the lower left corner, as well as the dimensions of the cutting surface 2 and the knife shank 3, it can be achieved that the knife is balanced overall with respect to the axis of rotation 8, that is to say that the axis of rotation 8 runs through the center of gravity of the knife insert 1. This contributes to a particularly smooth running during the operation of the cutting device.

In Figure 2a it can be seen that the cutting surface 2 has saber-shaped curved cutting edges 19 on both sides.

The embodiment of Figure 2b differs from that of Figure 2a only in that the connecting element 4 is arranged over the rear end of the cutting surface 2 and is not laterally offset. 2c, d and e show further knife shapes, the cross section of the connecting element 4 appearing in FIG. 2e in the form of a regular hexagon. In the lower area of the connecting element, as indicated by a broken line, a corner of the hexagon is completely milled or ground away, so that the hexagon in the connecting area can be welded to the shaft 3 over a larger area.

The knives shown can have cutting edges either only on one side or also on both sides.

A spindle 6 can be seen in FIG. 3, which performs rotary movements oscillating about an axis of rotation 9 during operation. The maximum angle of rotation for these movements is generally less than 20 °.

The spindle 6 consists of a multiply graduated cylindrical structure, the lower cylinder parts having an enlarged diameter being designed to accommodate a knife insert. It became conventional for the well-known knives a fastening by means of a screw is provided in the thread 10, but the screw was not firmly connected to the knife insert, but merely fixed the knife in a certain position.

The spindle 6 described here still leaves such an attachment option open, since in addition to the receptacle 11 with a star-shaped cross section, the thread 10 is provided inside the spindle 6. A conventional knife comes with its fastening part either on the lower surface of the disc 13 or the hexagonal disc 14 to the plant. The hexagon washer 14 also serves to hold the spindle 6 with the aid of a wrench or the like when fastening a knife insert or in other work on the spindle 6.

The receptacle 11 for the plug-in knife insert 1 is star-shaped with eight right-angled outer corners, as can best be seen in the view from below shown in FIG. In this way, it is also possible to insert a four-sided connecting element 4, as shown in FIGS. 1 and 2a to 2d, into the receptacle 11. The corners of the square engage in every second corner of the octagonal star 11. The octagonal cross section of the receptacle 11 makes it possible to insert the knife insert 1 into the receptacle 11 rotated by a fixed angle of 45 ° or a multiple thereof. The arrangement of the knife insert 1 can thus be optimally adapted to the given space and working conditions. The knife movement itself is not influenced by the orientation of the connecting element 4 in the receptacle 11, since the axis of symmetry 8 of the connecting element 4 coincides with the axis of rotation 9 of the spindle 6.

The disc 13 at the lower end of the spindle 6 also has a bore 7 through which a locking pin 15 can be inserted. The distance of the bore 7 to the upper end face of the receptacle 11, to which the connecting element 4 of the knife insert 1 strikes when inserted, corresponds essentially to the distance of the groove in the connecting element 4 from its upper edge or upper side, which strikes the end face of the receptacle 11. If the locking pin 15 is inserted into the bore 7 after the connecting element 4 has been inserted into the receptacle 11, the securing pin lies in the groove 5 of the connecting element 4 and thus prevents the connecting element 4 from moving axially or slipping out of the receptacle 11 Figure 5 shown locking pin is available in the illustrated embodiment as a ring spring pin in standardized sizes. The second leg 16 of the locking pin 15 engages in a groove 12 provided on the outer edge of the disk 13, the curvature of the second leg 16 also being adapted to the curvature of the disk 13. Because of the design of the locking pin as an annular spring element, the leg 16 of the locking pin 15 presses against the outer edge of the groove 12, while the leg 17 of the locking pin 15 is received in the bore 7 of the washer 13 and in the groove 5 of the connecting element 4. In this way, the locking pin 15 cannot slip out of the bore 7 and the groove 5, so that the connecting element 4 or the knife insert 1 are held securely. The bore 7 can be arranged as desired in the disk 13, as long as only its part lying radially inward with respect to the disk 13 is aligned with the groove 5 of an inserted connecting element 4.

It is also possible to provide a plurality of such bores 7, which may also intersect, in the disk 13.

The spindle 6 shown can thus be used either for the fastening of the hitherto known knives or knife inserts which are U-shaped in side view, as well as for the new plug-in knife inserts 1 according to the present invention.

A great advantage of the plug-in knife inserts in Verbin tion with the corresponding spindle lies in the fact that the knife inserts can be released very quickly by pulling out the locking pin 15 and removing the connecting element 4 from the receptacle 11 and, if necessary, can be replaced. Especially when work is constantly changing, for example when removing windshields of different types of cars in a repair shop, the possibility of a quick knife change is very advantageous.

In addition, because of the proximity of the second L-leg 3 to the axis of rotation 9, an unintentional striking of this knife leg in narrow spaces between the body and the windshield is avoided.

Of course, in addition to the described embodiments, other embodiments of the knife insert and the associated spindle are also conceivable, as have already been mentioned in part. For example, the thread 10 can be dispensed with, the receptacle 11 can have a hexagonal or twelve-sided cross section, and the connecting element 4 can also be secured in another way against axial displacement, e.g. by a circlip, a snap coupling or the like.

In the embodiment shown in FIG. 2d, in contrast to the other embodiments, the connecting element 4 is arranged on the outside, ie on the side of the second L-leg 3 facing away from the cutting surface. The connecting element 4 could also have a slot in its lower part, the L-leg 3 being received in the slot 3 and being welded there. In such an embodiment or also in the embodiment according to FIG. 2e, in which the connecting element 4 is milled on one side in the lower region, the axis of rotation 9 can run through the L-leg 3, so that the oscillatory rotary movements of the L-leg 3 thereby have a minimal Have hub.

In Figure 6, an adapter 20 is shown in a side view. The adapter 20 has a slot 21 for receiving a leg 3 of an L-shaped knife insert 1. The leg 3 of the knife insert 1 can be fastened with a screw in the slot 21 of the adapter 20 in that the screw into the thread 23 of the Bore 22 is screwed in and thereby clamps the leg 3. For this purpose, the leg 3 can have a suitable bore through which such a screw is passed. The leg 3 of the knife insert 1 could also be held in the slot 21 by other clamping elements, in particular the slot could also be formed between a movable part of the adapter 20 and the rest of the adapter part.

The adapter 20 is fastened to the spindle 6 with the aid of a screw, the screw being screwed into the thread 10 of the spindle 6. The adapter 20 has a screw head receptacle 24 and a through hole 25.

Furthermore, the adapter 20 has a recess 26 for receiving the hexagon washer 14 so that it can be connected to the spindle 6 in a rotationally fixed manner.

The adapter 20 can be attached both to the conventional spindles and to the spindles 6, which according to the invention has a receptacle for insertable knife inserts.

In order to have as much free space as possible above the cutting surface of the knife insert 1, the adapter 20 is chamfered on the side opposite the slot 21.

Claims (10)

1. Knife insert for tools with an oscillating head, preferably of the type used for the separation of rubber or adhesive beads on windshields, with a cutting surface which is limited by one or more cutting edges, characterized in that the knife is perpendicular to it Cutting surface (2) is angled in an L-shape, the cutting surface (2) forming a first L-leg, and that the second L-leg (3), which extends essentially vertically from the cutting surface (2), is a connecting element (4) Has connection with an actuating tool (6). 2. Knife insert according to claim 1, characterized in that the connecting element (4) with the second L-leg (3) is welded. 3. Knife insert according to claim 1 or 2, characterized in that the connecting element (4) is a polygonal part in cross section. 4. Knife insert according to claim 3, characterized in that the connecting element (4) is at least partially designed as a square or hexagon. 5. Knife insert according to claim 1 or 2, characterized in that the connecting element (4) with the tool holder (6) can be screwed. 6. Knife insert according to one of claims 1 to 5, characterized in that the connecting element (4) has a bore or a groove (5) in its surface, the groove (5) or the bore being substantially perpendicular to the direction of insertion of the knife insert (1) extends into the tool carrier (6). 7. Knife insert according to one of claims 1 to 6, characterized in that a locking pin through a suitable bore (7) in the tool carrier (6) to be guided into the groove (5) or bore of the connecting element (4) can be inserted. 8. Knife insert according to one of claims 1 to 7, characterized in that the connecting element (4) at a distance from the cutting surface (2) on the second L-leg (3) is attached. 9. Knife insert according to one of claims 1 to 8, characterized in that the connecting element (4) tapers in the direction of the cutting surface (2). 10. Knife insert according to one of claims 1 to 9, characterized in that the connecting element (3, 4) can be positively inserted into an adapter (20) which can be screwed onto a spindle (6).

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