EP0803334B1 - Rotary knife - Google Patents

Abstract

The knife blade (2) is chamfered on at least one side and has a toothed periphery. The individual tooth segments are separated from each other by slits (4) running inwards from the periphery at a fixed angle to the radius. The slits have at least three different depths in a periodic alternation. The longest slit of each period extends as far as the area where the chamfer begins (5).

Description

The invention relates to a circular knife, in particular for Cutting of hydraulic hoses reinforced with reinforcement, according to the preamble of claim 1 or claim 2.

Such circular knives are made of tool steel, high-speed steel, Carbide, as well as other special materials, the cutting area being coated or surface-treated can be.

In addition to cutting reinforcement-reinforced hydraulic hoses, they also become Cutting other hoses, rubber and plastic parts with and without steel, non-ferrous metal, plastic and others Reinforcements and reinforcements used.

Circular knives with a smooth cutting edge and those with are known serrated or slotted cutting edge and knife with special Cut, for example with a cullet cut. The knife with a smooth cutting edge have the disadvantage that - depending on Stress - often need to be re-grinded to achieve a to get consistently good cut quality. This creates a considerable amount of time for changing the Circular knives and shipping for regrinding as well as substantial Regrinding costs.

In addition to the disadvantage of reduced cut quality, blunt adheres Circular knives with a smooth cutting edge the disadvantage stronger Overheating when cutting. Overheating results also from mistakes when cutting, such as when that Cuttings have too little pre-tension or too feed is faster or too slow when cutting.

Especially in series production and especially when cutting of hoses with spiral wire inlays, it also happens Overheating, which leads to structural changes in the cutting area, lead to thermal stresses and cracks. As a result of Cracking occurs, material breaks on the edge circumference.

In many cases, such a damaged knife is also worn out Regrinding, i.e. by grinding away the break points, not recoverable. The fine cracks and / or the structural changes often lead to cracks after a short period of use and outbreaks.

Circular knives have therefore already been developed that work on your Are circumferentially toothed, the tooth segments of the same length Slots are limited. These versions have better ones Properties and service life as a knife with a smooth Cutting edge. The arranged on the circumference of the circular knife Avoid excessive overheating in the area of the slots Cut and ensure a lower incline when new to cracks and breakouts after wear-related However, the reduction in tooth height or slot depth increases again. This also applies if the distances between the slots are too big.

A circular knife is also known from US Pat. No. 1,975,219. in the case of the radially extending slots with two alternating depths are provided. Would such a knife for cutting with reinforcement reinforced hydraulic hoses, the result would be disadvantages mentioned above.

What has been said inevitably also applies in the event that a such knife has been sharpened more often. In extreme cases then you get a circular knife with a smoother one Cutting edge, which has the disadvantages described above is. It is possible, the toothing or slotting to renew on the worn circular knife, which is very is complex and very expensive.

The invention is based on a prior art, such as he has been described above, based on the task To create circular knives, which on the one hand due to its special Cutting geometry less or not at all to overheating tends, which increases the service life and which if necessary can be reground more often without it being his loses advantageous properties.

The invention solves this problem according to claim 1 in that the depth of the slots periodically alternating at least three has different dimensions, such that to a maximum length Slit that is in the area of the start of the chamfer or above runs out, initially a minimally long slot follows, which in turn is followed by a slot, the length of which lies between the first two, followed by another minimal long, that as the tooth segment width the distance between two maximum long slots is defined and the ratio from segment width to slot depth> 1.2 and the angle between the slots (4) and the radius between 10 ° and 20 ° is.

The invention also achieves this object according to the subordinate one Claim 2.

Such circular knives have the following common Advantages on:

There is a maximum self-cooling effect through forced convection in the cutting area thanks to the optimized gradation of as many slots / slots as possible with the greatest possible length the same achieved. The forced convection takes place due to the relative movement between the in the cutting area Circumferentially arranged slots and the almost standing ambient air. As a result, the resulting frictional heat on the Cutting edge and its flanks quickly removed. That will be with the Alternative according to claim 1 by the special number, special Arrangement of the slots as well as the special ratio reached from segment width to slot depth.

The slots of different lengths thus result a swirl of air that affects the self-cooling effect reinforced.

Such a periodic gradation in the order given in connection with the oblique slot course relative to Radius also ensures an improved Cut quality with optimal stability and prevents that Break out of segments.

This increases the overall service life of the knife, especially Repeated regrinding due to the cutting edge geometry of the knife is possible without first Change geometry and thus the advantageous properties.

Although it is already in the prior art (DE-A-29 02 661) circular saw blade known, which is a usual on its circumference Has teeth, but at larger intervals slots of different lengths are arranged, some of them almost extend to the center hole of the saw blade.

However, these slots have another according to DE-A-29 02 661 Task as the slots in the circular knife according to the invention. The known slots are intended to serve as resonance disasters to prevent in the saw blade.

The same advantages as with the first alternative are at the alternative according to claim 2 by the combination of Slits and elongated holes that are aligned with them.

The embodiment according to claim 2 is a continuous slot on which a slot / slot combination consisting of a shorter slot and follows three subsequent oblong holes, for example which is another slot / slot combination consisting of one longer slot and a subsequent longer one Long hole follows. Then a new period begins Slot or slot / slot combinations.

In the embodiment according to claim 2, each slot / slot combination the same length, so ends on one common circular line, wherein according to claim 3 the end of Slot / slot combinations on the circular line an ice-shaped Has widening. Through these circular holes is achieved in addition to the swirling effect that the inclination to thermal stresses and the subsequent cracking and Outbreaks are counteracted.

Such circular expansions can of course also be realized in the alternative according to claim 1.

Claim 4 proposes a further embodiment of Slot / slot combinations, which is designed so that a combination with a slot with an aligned slot follows from two aligned elongated holes that are offset to the adjacent slot of the slot / slot combination are arranged.

An embodiment is also possible in which the regular Spaces arranged on the circumference in each case two slots are aligned.

If such a knife becomes dull in the course of its operating time, it can easily be reground so that it can be an at least similar constellation of slot / slot combinations results.

The division should be chosen as large as possible without the Endanger the stability of the emerging segments. According to claim 5 should be the ratio of segment width to slot depth > 1.2. With a given division you get the Segment width and thus the maximum permissible slot depth. at the embodiment according to the invention with three or more Grading of the slot depths is called the segment width, the distance defined between two slots of the same length.

According to claim 6, the slot width or also is preferred Width of the elongated holes chosen between 1 mm and 1.2 mm. With less Dust settles broadly in the slots or elongated holes that negatively affects cooling. Slot widths, which are larger than 1.2 mm lead to negative effects in the quality of the cut.

According to claim 7, the slots or the slots and with them aligned elongated holes at an angle of 10 ° to 20 ° in the direction of rotation against the radius, so that in the direction of rotation the beginning of the slot on the circumference of the circular knife the end of the slot or slot / slot combination lags.

In a preferred embodiment according to claim 8 the angle 15 °.

A further improvement in tool life before regrinding the cutting edge is characterized by a relatively acute bevel angle Reached cutting edge, which is formed according to claim 9 double-ended and a bevel angle of> 3 °, preferably 3 - 4 ° having. A pre-chamfer is not necessary here.

A further increase in the service life of the knife and an improvement the cut quality is thereby according to claim 10 achieved that the cutting area is coated, whereby according to Claim 11, the coating can consist of titanium, or according Claim 12 made of titanium carbon nitride.

According to claim 13, the hardness of the knife material is, for example more than 60 HRC in the high-speed steel version.

A circular knife is thus obtained by the invention, which by the special geometry of the cutting edge, by the chosen one Hardness of the material and possible coatings in the Cutting area has a significantly longer life and which can be reground several times if necessary, without much change in the special geometry of the cutting edge, so the benefits that a new knife has, too then are still roughly given.

The invention is illustrated below with reference to drawings and explained in more detail.

Fig. 1:

eine erste Ausführungsform eines Kreismessers mit geschlitzter Schneide,

Fig. 2:

ein Kreismesser gemäß Fig. 1 im Schnitt,

Fig. 3:

in vergrößerter Darstellung einen Ausschnitt aus Fig. 1,

Fig. 4:

eine Ausführungsform eines Kreismessers mit Schlitz-/Langlochkombinationen im Schneidenbereich,

Fig. 5:

in vergrößerter Darstellung eine Einzelheit aus Fig. 4,

Fig. 6:

eine Ausführungsform wie in Fig. 1, jedoch mit größerer Teilung,

Fig. 7:

in vergrößerter Darstellung eine Einzelheit aus Fig. 6.

Show it:

Fig. 1:

a first embodiment of a circular knife with slotted cutting edge,

Fig. 2:

a circular knife according to FIG. 1 in section,

Fig. 3:

in an enlarged view a section of FIG. 1,

Fig. 4:

an embodiment of a circular knife with slot / slot combinations in the cutting area,

Fig. 5:

4 in an enlarged representation,

Fig. 6:

an embodiment as in Fig. 1, but with a larger division,

Fig. 7:

an enlarged representation of a detail from FIG. 6.

1, 4 and 6, there is one quadrant each Represents circular knife, generally with the reference numeral 1 is provided.

As can be seen from Fig. 2, the cutting edge 2 is in all Embodiments formed double-phase, the bevel angle for example, is 4 °, but can also be 3 °.

In the exemplary embodiment according to FIGS. 1 and 3, the cutting area is toothed, the individual tooth segments 3 are formed by slots 4, which are at an angle relative to the radius r of 15 ° from the circumference in the present example Extend towards chamfer 5. It hurries in the direction of rotation the knife the beginning of the slot on the circumference of the cutting edge 2 Slot end after. As can be seen from FIGS. 1 and 3, point the slots 4 have different depths in a periodic sequence on. A minimally long slot 4 is followed by a minimal one longer, followed by a slit, the depth of which is approximately half the length of the maximum long slot and double of the minimally long slot. This concludes a minimally long slit reappears, whereupon the period starts again.

A division of 112 is chosen here, the slot depth with a circle diameter of 300 mm 5, 10 and 20 mm and the slot width is 1.2 mm. The longest slot 4 ends in the area of the start of the chamfer 5.

4 and 5 is another embodiment shown.

Here, a maximum long slot 4 is provided, which is in the area the beginning of the chamfer 5 ends. On this continuous Slot 4 follows a slot / slot combination 4, 6, wherein the slot has a minimal length and - with this aligned - connect three elongated holes 6 arranged one behind the other. The last slot 6 ends on the same circular line like the maximum long slot 4.

This slot / slot combination 4, 6 is followed by another Slot / slot combination, the slot 4 has a depth, the between those of the maximum long slot 4 and the minimally long slot of the previous combination lies. An elongated hole 6 is aligned with this medium-length slot, whose length is chosen so that it is on the same circular line ends like the maximum long slot 4.

The slots 4 and elongated holes 6 ending on this circular line are provided with circular widenings 8 at this end.

Such expansion 8 can of course also with the slots, or slot / slot combinations of the previous described embodiments can be realized.

The angle of inclination of the slots or slot / slot combinations is the same as in the other examples 15 °, the width of the slots 4 or slots 6 is 1.2 mm.

However, in the latter example there is a division of 200 selected, with a knife diameter of 520 mm. These dimensions are only mentioned as examples. In principle, at predefined division the ratio of segment width to Slot depth> 1.2 to be selected, with segment width each as the distance between slots 4 of the same depth is defined.

6 and 7, an embodiment is shown which is roughly constructed like the exemplary embodiment according to FIGS. 1 to 3 is, however, with a knife diameter of 520 mm Has division of 200. In this latter example the maximum long slot extends beyond the beginning of the chamfer 5 beyond.

In all embodiments, the cutting principle is due to the Geometry of the cutting edge is more like grinding. With the acute-angled cutting edge interrupted by slits the material, e.g. Rubber and the reinforcements (e.g. higher strength Steel wire) worn point or line by line, similar like cut-off, but with an extremely narrow, defined one Cutting edge. The cutting process is reinforced by the impulse effect the segments of the cutting edge.

The dash-dotted line 7 indicates the beginning of the cutting area on, which is provided with a coating, for example made of titanium carbon nitride. The layer thickness can be 1.5 to 4 µm be. Such a coating can of course be realized in all embodiments.

Claims (13)

1. A circular cutter (1), in particular for cutting hydraulic tubes reinforced with armouring, comprising a blade chamfered on at least one side and toothed over its circumference, wherein the individual tooth segments (3) are separated from one another by slits (4) extending inwards from the circumference at a fixed angle to the radius (r), characterised in that the slits (4) have at least three different depths changing periodically so that a slit of maximum length, extending into the region of the start (5) of the chamfer or therebeyond, is followed first by a slit of minimum length, itself followed by a slit of a length lying between the first two, in turn followed by a slit of minimum length, and in that the distance between two slits (4) of maximum length is defined as the width of the tooth segment, and the ratio of segment width to slit depth is > 1.2 and the angle between the slits (4) and the radius is between 10° and 20°.
2. A circular cutter (1), in particular for cutting hydraulic tubes reinforced with armouring, comprising a blade chamfered on at least one side and toothed over its circumference, wherein the individual tooth segments (3) are separated from one another by slits (4) extending inwards from the circumference at a fixed angle to the radius (r), characterised in that at least each second slit (4) is aligned with at least one slot (6, 6'), the width of which is substantially equal to the width of the slit, in that each slit/slot combination (4, 6, 6') ends on a common circular line and in that at least one combination comprising a slit (4) and at least one slot (6, 6') aligned therewith is provided on each side symmetrically to a slit (4) extending as far as the circular line.
3. A circular cutter according to claim 2, characterised in that the end of the slit/slot combination (4, 6, 6') has a circular opening (8) on the circular line.
4. A circular cutter according to either one of claims 2 and 3, characterised in that at least one slot (6') is provided between two slit/slot combinations (4, 6) starting at the circumference of the cutter (1), this at least one slot (6') being offset relative to the adjacent slot (6) of the slit/slot combination (4, 6).
5. A circular cutter according to any one of claims 2 to 4, characterised in that the ratio of segment width to slit depth is > 1.2, the segment width being the distance between two slits (4) of equal depth.
6. A circular cutter according to any one of claims 1 to 5, characterised in that the slit width is 1 mm to 1.2 mm.
7. A circular cutter according to any one of claims 1 to 6, characterised in that the slits (4) are inclined at an angle of 10° to 20° to the radius (r) in the direction of rotation.
8. A circular cutter according to claim 1 or 7, characterised in that the angle is 15°.
9. A circular cutter according to any one of claims 1 to 8, characterised in that the blade (2) is dual-chamfered and has a chamfer angle of 3° to 4°.
10. A circular cutter according to any one of claims 1 to 9, characterised in that the blade region is coated.
11. A circular cutter according to claim 10, characterised in that the coating comprises titanium.
12. A circular cutter according to claim 10, characterised in that the coating comprises titanium carbonitride.
13. A circular cutter according to any one of claims 1 to 12, characterised in that the hardness of the cutter is > 60 HRC when the cutter is made of high-speed steel.

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