EP2039482B1 - Segment knife - Google Patents

Abstract

The knife has a plate-shaped knife body (1) including a bent knife edge section (SA). Replaceable knife inserts (3) are provided at ends (E1, E2) of the edge section, respectively. The section has two knife edges made at the body. The section has a third knife insert (5) detachably fastened to the body, and a channel for retaining the third insert. The third insert has bent side surfaces corresponding to tapered inner flanks of the channel. The inserts (3) are made of metal, and the third insert is made of a material e.g. hard metal or ceramic, whose hardness is larger than that of the metal.

Description

The invention relates to a segment knife according to the preamble of patent claim 1.

The invention relates generally to the field of segmented blades for making a slot in a packaging material, in particular corrugated board. For this purpose segment knives are mounted on a rotating roll of a rotary cutting machine. To produce the slot, the segment blade, which is also referred to as the upper blade, is moved in a slot formed by two lower blades arranged in parallel. As a result, a slot is produced in the corrugated board located between the segment blade and the lower blades.

A segment knife according to the preamble of claim 1 is known from DE 20 2004 004 275 U1 known. A provided on a plate-like knife body convexly curved cutting section must be reground again and again to achieve perfect cutting result. For this purpose, the segment knife must be removed from a rotary cutting machine and subsequently transmitted to a grinding operation specialized in the grinding of such knives. Grinding the segment knives is costly and time consuming.

The object of the invention is to eliminate the disadvantages of the prior art. It should be specified in particular a segment knife with improved durability.

This object is solved by the features of claim 1. Advantageous embodiments of the invention will become apparent from the features of claims 2 to 13.

According to the invention, it is provided that an exchangeable first cutting insert is provided at least at one end of the cutting section. In practice, it has been shown that in particular the end, which first dips into the slot formed by the lower blade during the cutting process, wears particularly strong. This is attributed to the fact that the segment knife z. B. due to vibrations or the like. Not always exactly immersed in the slot formed by the lower blade. It may happen that when the segment knife plunges, the cutting edge located at one end collides with a cutting edge of the lower blade. As a result, the segment knife wears particularly strong at one end of the cutting section and must therefore be reworked. By providing an interchangeable first cutting insert according to the invention at one end of the cutting section, the reworking of the segment blade can be delayed by replacing the first cutting insert and thus its durability or service life can be increased. The replacement of the first cutting insert can advantageously be carried out on site at the operator of a rotary cutting machine. For this purpose, it is particularly not necessary to transmit the segment knife under cost and time to a specialized in the revision of segment knives grinding operation.

According to an advantageous embodiment of the invention, an exchangeable second cutting insert is provided at the other end of the cutting section. Such a segment knife is particularly suitable for rotary cutting machines in which alternately the one and the other end of the cutting portion first dips into the slot formed by the lower blade. Apart from that, such a segment knife can also be turned, that is mounted on the rotary cutting machine that instead of a worn first cutting insert the second cutting insert dips into the slot formed by the lower blade.

Conveniently, the cutting portion between the two ends on two cutting edges made on the knife body. Between the two cutting edges is usually a groove. The cutting edges may be formed in the form of a bow portion and in addition also wavy. In particular corrugated cutting edges, d. H. Serrated cutting edges are particularly well suited for making a cut or slit in a packaging material such as corrugated board.

According to an alternative, but particularly preferred embodiment, the cutting section has a plurality of third cutting inserts detachably fastened next to one another on the knife body. For this purpose, the cutting portion may have a groove for receiving the third cutting inserts.

According to a particularly advantageous embodiment, the third cutting inserts on a square outline. As a result, the third cutting inserts can be rotated by 90 ° at a wear of the opposite edges. The proposed third cutting inserts thus have two benefits. Thus, the period until the replacement of the third cutting inserts can be considerably extended.

Furthermore, it has proven expedient that the groove has beveled inner flanks and the third cutting inserts have correspondingly bevelled side surfaces to the chamfered inner flanks. As a result, the third cutting inserts advantageously center themselves when being fastened to the knife body.

It is possible to form the entire cutting section by exchangeable cutting inserts. In this case, the knife body serves only as a carrier for fixing the cutting inserts. For the operator of a rotary cutting machine, this results in the significant advantage that a segment blade according to the invention can be quickly and easily brought into a state by simple replacement of the first and possibly second cutting inserts and a replacement or turning of the third cutting inserts, which allows a renewed use. The replacement and / or turning of the cutting inserts requires no special expertise or the use of grinding machines. The segment knife according to the invention can be easily repaired on site again.

According to the predetermined by the intended use geometry of the cutting portion, the second and the third cutting insert may have the same geometry. The third cutting insert may also replace the second cutting insert.

According to an alternative embodiment, the first cutting insert is designed in the form of a cutting nose projecting from the cutting section.

The cutting inserts proposed according to the invention can be designed differently with respect to their material properties and thus are particularly well adapted to different stresses acting on the cutting section. Thus, advantageously, the first cutting insert and / or the second cutting insert of a first metal and the third cutting inserts can be made of a material whose hardness is greater than that of the first metal. The material used to make the third cutting inserts may be a cemented carbide or a ceramic. By the hardness of the for the production of the first and / or the second cutting insert of the material used is less than that of the material used to make the third cutting inserts, undesirable breakage in a collision of the first and / or cutting insert with an edge of the lower blades is avoided. In particular, the first and / or the second cutting insert can also be produced from a first metal conventionally used to produce the knife body. In a possible collision of the first and / or second cutting insert with an edge of the lower blade, there is only a deformation or abrasion. Once the first or second cutting insert is immersed in the slot formed by the lower blades, a collision can no longer occur. As a result, the third cutting inserts can be made of a particularly hard material, in particular hard metal or ceramic. The cutting edges formed by the third cutting inserts mounted next to one another on the knife body can be modeled on conventional cutting edges. You can describe a bow line. The cutting edges can also be modeled on a serrated edge.

If the entire cutting section of the segmented blade is formed by the proposed cutting inserts, a second metal can advantageously also be used to produce the knife body. It may be a steel that has a lower hardness than the first metal and is therefore easier to work.

The following table shows suitable metals for the production of the knife body as well as the cutting inserts: hardness DIN (17007) knife body 55-58 HRC 1.8550 first cutting insert
second cutting insert 58-65 HRC 1.7847; 17436; 17379 third cutting insert > 80 HRA B30S; B40S (Plansee)

Fig. 1

eine Schnittansicht durch ein erstes Segmentmesser,

Fig. 2

eine Querschnittsansicht durch das erste Segmentmesser gemäß Fig. 1,

Fig. 2a

eine Detailansicht nach Fig. 2 mit gelöstem dritten Schneideinsatz,

Fig. 3

eine Schnittansicht durch den ersten Schneideinsatz gemäß Fig. 1,

Fig. 4

eine Schnittansicht des Segmentmessers gemäß Fig. 1 mit einem weiteren ersten Schneideinsatz,

Fig. 5

eine Schnittansicht durch den weiteren ersten Schneideinsatz gemäß Fig. 4,

Fig. 6

eine Draufsicht auf einen dritten Schneideinsatz und

Fig. 7

eine Schnittansicht gemäß Fig. 6.

Embodiments of the invention will be explained in more detail with reference to the drawing. Show it:

Fig. 1

a sectional view through a first segment knife,

Fig. 2

a cross-sectional view through the first segment blade according to Fig. 1 .

Fig. 2a

a detailed view after Fig. 2 with dissolved third cutting insert,

Fig. 3

a sectional view through the first cutting insert according to Fig. 1 .

Fig. 4

a sectional view of the segment blade according to Fig. 1 with another first cutting insert,

Fig. 5

a sectional view through the other first cutting insert according to Fig. 4 .

Fig. 6

a plan view of a third cutting insert and

Fig. 7

a sectional view according to Fig. 6 ,

In the figures, a knife body 1 is made of a metal plate, which z. B. may have a thickness of 6 to 125 mm. This metal plate 1 has a convex curved Cutting section SA on. As in particular from Fig. 2 it can be seen, the cutting section SA has two first cutting edges K1 and K2 extending in parallel planes. At one end E1 of the cutting portion SA is detachable, z. B. by means of a first screw 2, a first cutting insert 3 is attached. The first cutting insert 3 is positively received in a corresponding thereto on the knife body 1 recess. The first cutting insert 3 is provided here with a cutting nose 4 protruding beyond the cutting section SA.

At the other end E2 of the cutting portion SA, a - not shown here - second cutting insert be releasably secured. The second cutting insert may be formed in its geometry corresponding to the first cutting insert 3, so that the segment blade is formed symmetrically with respect to a plane perpendicular to the first cutting edges K1, K2 symmetry plane.

Like from the Fig. 1 and 4 it can be seen, the cutting section SA next to the first cutting insert 3, a plurality of adjacent and arranged in a row third cutting inserts 5, which are each connected with second screws 6 releasably connected to the knife body 1. In the present embodiment, the entire cutting section SA is formed by the flush adjacent cutting inserts 5.

As in particular from Fig. 2a can be clearly seen, the knife body 1 is provided on its convexly curved side with a groove 7, the inner edges 8 with an outer side A of the knife body 1 an angle α of 8 to 18 °, preferably 10 to 13 °, include. One of the groove 7 facing portion 9 of the side surfaces S of the third cutting inserts 5 is associated with a to the angle α of the inner edges 8 Beveled, so that the third cutting inserts 5 are positively and thus self-centering inserted into the groove 7. In the inserted state, each of the third cutting inserts 5 sits with its bottom 10 on a base 11 of the groove 7. For this purpose, the base 11 of the groove 7 is formed of a plurality of adjacent flat surfaces, in the center of each a threaded hole for fixing the second screw 6 is provided.

A the, preferably flat, bottom 10 opposite cutting surface 12 of the third cutting inserts 5, in the in Fig. 6 shown top view on a square outline. The, preferably concavely curved, cutting surface 12 is bounded by four, preferably concave curved, further cutting edges k1 to k4. In the center of the cutting surface 12, an opening 13 for passing the second screw 6 is provided. The geometry of the third cutting inserts 5, in particular the geometry of the further cutting edges k1 to k4, is designed such that, when the third cutting inserts 5 are mounted on the knife body 1, there are continuous first cutting edges K1, K2.

As in particular from Fig. 2a As can be seen, a width B in the cross section of the third cutting insert 5 is greater than its height H extending from the bottom 10 in the direction of the cutting surface 12. The ratio of width B to height H can be between 1: 1 and 1: 2. Conveniently, the ratio of width B to height H is in the range of 1.3 to 1.7.

At the in Fig. 4 shown another segment blade, a further first cutting insert 14 is releasably attached instead of the first cutting insert 3. The further first cutting insert 14, unlike the first cutting insert 3, has no projecting cutting nose 4. Although in the Fig. 4 only at the first end E1 another first Cutting insert 14 is provided, it is also possible according to an embodiment of the invention that a similarly shaped - not shown here - another second cutting insert at the second end E2 of the cutting portion SA can be releasably attached.

The knife body 1 is suitably made of a surface hardened steel, for. B. Nitriding steel no. 1.8550 (DIN 17007) with a Rockwell hardness of about 56 HRC.

The first cutting insert 3, the further first cutting insert 14 and possibly provided second cutting inserts (not shown here) can advantageously be produced from the following metals: Nos. 1.7847, 1.7436 or 1.7379 (DIN 17007). Such metals have a Rockwell hardness of 58-60 HRC.

The third cutting inserts 5 are made of a material that is harder than the metals used to make the knife body 1 or the first and second cutting inserts 3, 14. It may expediently be the following materials: ceramic, hard metal, in particular hard metal with a Rollwell hardness in the range of 85-90 HRA, preferably 87-89 HRA. Such hard metals are z. B. offered by the company Plansee GmbH under the product names "B30S" or "B40S".

In the embodiment of the segmented blade proposed according to the invention with detachable cutting inserts provided thereon, it is possible to considerably increase the durability of the segmented blade. A repair of the segment knife can be done by simply changing or turning the cutting inserts. The repair can therefore be carried out with less effort and in particular at the site of the operator of a rotary cutting machine.

Claims (13)

1. Segment knife for producing a slit in a packaging material, in particular in corrugated cardboard, cardboard or similar, with a plate-type knife body (1) having a curved cutting section (SA),
   characterized in that
   an exchangeable first cutting insert (3) is provided on at least one end (E1) of the cutting section (SA).
2. Segment knife as defined in claim 1, wherein an exchangeable second cutting insert is provided on the other end (E2) of the cutting section (SA).
3. Segment knife as defined in one of the preceding claims, wherein the cutting section (SA) has two cutting edges (K1, K2) provided on the knife body (1) between the two ends (E1, E2).
4. Segment knife as defined in claim 1 or 2, wherein the cutting section (SA) has a plurality of third cutting inserts (5) mounted detachably next to each other on the knife body (1).
5. Segment knife as defined in claim 4, wherein the cutting section (SA) has a groove (7) for holding the third cutting inserts (5).
6. Segment knife as defined in claim 4 or 5, wherein the third cutting inserts (5) have a quadratic contour.
7. Segment knife as defined in one of the claims 4 to 6, wherein the groove (7) has slanted inner flanks (8) and the third cutting inserts (5) have slanted side surfaces (9) corresponding to the slanted inner flanks (8).
8. Segment knife as defined in one of the claims 4 to 7, wherein the second cutting insert (5) and the third cutting inserts have the same geometry.
9. Segment knife as defined in one of the claims 4 to 8, wherein the first cutting insert (3) and the third cutting inserts (5) have the same geometry.
10. Segment knife as defined in one of the preceding claims, wherein the first cutting insert (3) is shaped in the form of a cutting tab protruding from the cutting section (SA).
11. Segment knife as defined in one of the claims 4 to 10, wherein the first cutting insert (3) and/or the second cutting insert (5) is made of a first metal and the third cutting inserts are made of a material whose hardness is greater than that of the first metal.
12. Segment knife as defined in claim 11, wherein the material is a hard metal or ceramic.
13. Segment knife as defined in claim 11 or 12, wherein the knife body (1) is made of the first metal or of a second metal.

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