DE9015344U1 - Circular knife - Google Patents

Description

Remscheid, 05.11.1990

Circular knife

The invention relates to a circular blade for cutting machines, in particular for separating, cutting or dividing fibrous materials such as hygiene paper rolls, household paper rolls, etc.

Circular knives made of solid steel for cutting such materials are already known.

They are made from steels such as 80CrV2, 155CrVMol2.1 or 100Cr6, are heat treated by tempering or hardening and must then be straightened, ground plane-parallel or conically and finally sharpened by forming a bevel.

The most important criteria for the production of circular knives made of solid steel are:

1. Material quality

2. Blade thickness

3. Blade diameter

The material quality and the associated heat treatment are not only decisive for the cutting ability of the knife, but also determine the straightening and tension behavior of the circular knife.

Particularly in the case of blade thicknesses that are small in relation to the outer diameter, internal stresses caused by heat treatment, straightening, external forces or one-sided heating have an extremely strong effect on the running behavior of these tools.

As the tool diameter increases, a larger blade thickness must be selected to ensure the required tool rigidity. In addition, an optimum level of toughness and hardness must be available for the material selected.

While the hardness of the solid steel circular knives mainly influences the cutting ability of the tool, the right toughness is crucial for the straightenability of the thin, disc-shaped tool.

As toughness decreases, hardness and brittleness generally increase, which makes straightening more difficult and the tendency to fracture greater above 60 to 62 HRC.

The high hardness required for good cutting ability cannot therefore be used on solid steel circular knives for reasons of toughness. By using SS and HSS cutting materials with higher hardness, an improvement in cutting ability can be achieved, but the increase in service life achieved is achieved at the cost of much more expensive circular knives.

In order to keep tool costs as low as possible, such circular knives must be made from cheaper materials such as 80CrV2 etc.

The straightening and introduction of residual stresses to improve the running quality and cutting behavior of the circular knives is carried out using hand hammers, the pins of which generally have to have a small radius in order to achieve a pre-stressing effect.

The introduction of such residual tool stresses to compensate for the local thermal stresses in the cutting area of the circular blades can only be achieved to a very limited extent due to the high material hardness.

For these reasons, it is only possible to influence the bending stiffness, the natural frequency distribution and thus the vibration behavior of the circular blades during rotation to an insufficient extent. Even mechanical deformation using rollers with small contact radii can only introduce insufficient tangential tensile stresses in the cutting area of the circular blades, which are therefore unable to compensate for the high thermal pressure stresses that occur during the cutting process. Circular blades generally run at cutting speeds of approx. 30 m/sec and can perform continuous circular or back-and-forth feed movements. After the cut has been made, they either run through an idle section or briefly return to their rest position. During this time, the paper roll is transported at the same time and, if necessary, resharpened, whereby a sharpening disk running in the opposite direction is brought against the rotating circular blade on the circumference from each side.

This process, which is repeated after about 6 to 8 cuts, is necessary due to the high level of knife wear, which is also caused by the additional addition of waste paper, which can sometimes contain a large amount of glue.

As a result, with a high number of cuts, the number of resharpenings increases linearly, continuously reducing the usage height of the circular blade and automatically leading to high circular blade consumption.

The object of the present invention is therefore to develop a circular knife with better wear properties, longer sharpening intervals or lower sharpening and tool costs as well as good straightening, tension and vibration behavior.

This object is achieved according to the invention in that segment-like cutting elements made of highly wear-resistant materials, such as high-performance high-speed steel produced by powder metallurgy, hard metal, oxide ceramics, etc., are provided in a special way on the periphery of a circular carrier body, which have a fastening that corresponds to the stresses.

A preferred embodiment of the invention is characterized in that segment-like cutting elements (2) with high wear resistance are inserted seamlessly and without gaps into a circular carrier body (1) which is radially slotted in the upper peripheral area (9), and are connected to one another and to one another by riveting or pinning (3) and/or gluing (6).

The particular advantage of this design is that the expensive cutting material can be minimized by choosing a segment-like cutting element that is very thin in relation to the thickness of the carrier body and can be completely supported on both sides by the circular carrier body and secured against cutting and centrifugal forces by riveting, pinning and/or gluing.

The embodiment shown in Figure 1 according to claim 1 allows the use of a relatively inexpensive carrier body material such as 75CrI, 75W3 or 80CrV2, since the hardened and easily straightenable carrier body (1) does not perform any cutting functions and is therefore subject to almost no wear. Rather, its task is to take on load-bearing and supporting functions.

A further advantageous embodiment of the invention according to claims 1 and 2 is shown in Figure 2.

While the peripheral area corresponds to the segment cutting element structure shown in Figure 1 and explained in claim 1, the circular carrier body (1) is composed of two halves (1.1 and 1.2).

The advantage of such a design lies in the simple manufacture of the carrier body slot, which can be created by turning recesses on the individual carrier body halves.

A further advantage of the inventive design according to Figure 2 lies in the very good vibration damping properties of this circular knife.

Figure 3 shows another embodiment of the invention in which the segment-like cutting elements (2) are attached to the circular carrier body by means of a "tongue and groove connection".

Here, the spring (8) is on the cutting material-bearing part and the groove

(9) on the circular carrier body (1) which, as shown in Figure 2, can optionally be composed of two halves (1.1 and 1.2).

Here too, the fastening is done by riveting or pinning

(3) and/or bonding (6).

To avoid lateral displacement, pins or sleeves (7) are arranged so that half of them engage radially in the contacting segment-like cutting element inserts.

Figure 4 also shows a tongue and groove connection between segment-like cutting elements (2) and carrier body (1).

However, the groove (9) is located in the hard segment cutting element (2) and the spring is on the rigid carrier body (1). The segment cutting elements are also secured against lateral displacement by radially arranged pins and sleeves (7), each of which extends halfway into the segment cutting elements. The segment cutting elements (2) and carrier body (1) are also fastened by riveting or pinning and/or gluing (6).

Figure 5 shows the overlap connection (11/12) explained in claim 5 between the hard segment cutting elements (2) and the rigid, circular carrier body (1).

Here too, the fastening is carried out by means of riveting or pinning (3) and/or gluing (6).

For the lateral fixation of the segment cutting elements (2) to one another, either an arrangement of radial pins or radial sleeves (7), half of which protrude into the segment cutting elements in the area of the joints, or an axially arranged connecting rivet can be used.

- 10 -

- 10 Figure 1 Partial view of a circular knife with slotted carrier body, inserted, hard segment cutting elements, as well as riveting or pinning and/or gluing

1 circular support body,

2 hard segment cutting elements,

3 rivet, or clamping pin or clamping sleeve,

4 waders,

5 Pre-wate

Figure la Section AB from Figure 6 Adhesive layer, 9 Slot in the carrier body

Figure Ib Cut CD from Figure

- 11 -

Figure 2 Partial view of a circular knife with a split and slotted carrier body, inserted, hard segment cutting elements, as well as riveting or pinning and/or gluing.

Halves of a circular, protected carrier body, hard segment cutting elements, rivet, or clamping pin or clamping sleeve,

4 W a t e ,

5 Pre-wate

1.1 and 1.2

2
3

Figure 2a Section AB from Figure 2

6 adhesive layer,

9 Slot in the carrier body,

10 Partial joint _with adhesive layer

Figure 2b Section CD from Figure 2

_ 12 _

_ 12 _

Figure 3 Partial view of a circular knife with slotted and possibly split carrier body, into whose slot 9 the webs of the hard segment cutting elements protrude, with riveting or pinning and/or gluing 6.

1 circular, slotted carrier body,

2 hard segment cutting element,

3 rivet, or clamping pin or clamping sleeve,

4 waders,

5 V &ogr; r &ngr;; a t e

Figure 3a Section AB from Figure 3

6 (6 ¹ ) Adhesive layer

8 Segment cutting element web

9 Slot in the carrier body

Figure 3b Section CD from Figure 3

7 Radial pin or radial sleeve

_ 1 & o r; _

JL O

Figure 4 Partial view of a circular knife with slotted, hard segment cutting elements 2, into whose slots 9 the web 8 of the circular carrier body 1 projects, as well as riveting or pinning 3 and/or gluing 6.

1 circular support body with web formation 8,

2 hard segment cutting elements with slot 9,

3 rivet, or clamping pin or clamping sleeve,

4 waders,

5 Pre-wate

Figure 4a Section AB from Figure 4

6 adhesive layer,

8 carrier body web,

9 Slot in the segment cutting element

Figure 4b Section CD from Figure 4

7 Radial pin or radial sleeve

-1.4 -

Figure 5 Partial view of a circular knife with a stepped shoulder on the periphery of the carrier body and stepped, hard segment cutting elements, the tabs 11/12 of which are connected to one another by riveting or pinning 3 and/or gluing 6.

1 circular carrier body with a stepped step on the carrier body periphery,

2 stepped segment cutting elements,

3 rivet, or clamping pin or clamping sleeve,

4 waders,

5 Pre-wate

Figure 5a Section AB from Figure 5

6 adhesive layer,

11 flaps on the carrier body,

12 lobes on the hard segment cutting body,

4 waders,

5 V &ogr; r w a t e

Figure 5b Section CD from Figure 5

7 Radial pin or radial sleeve

- 15 -

Claims (5)

Remscheid, 05.11.1990 Claims 1. Circular blade for cutting machines, in particular for separating, cutting or dividing fibrous materials such as hygiene paper rolls, household paper rolls etc., characterized in that segment-like cutting elements (2) with high wear resistance are inserted without joints and gaps into a circular carrier body (1) which is radially slotted in the upper peripheral area (9), which are connected to one another and to one another by riveting or pinning (3) and/or gluing (6). 2. Circular knife according to claim 1, characterized in that the circular carrier body (1) which is radially slotted in the upper peripheral area is assembled from two halves (1.1 and 1.2) which are connected by means of gluing, soldering, welding or riveting (10). _ &ogr; 3. Circular knife according to claims 1 and 2, characterized in that the segment cutting elements (2) and the one- or two-part carrier body (1 or 1.1/1.2) are connected in a tongue and groove manner and are fastened by means of riveting or pinning (3) and/or gluing (6), whereby the groove (9) is formed in the carrier body (1) and the tongue (8) is formed on the segment cutting elements (2) and the joints of the segment cutting elements are secured against lateral displacement in the lower area of the segment cutting elements by radially arranged pins or sleeves (7). 4. Circular knife according to claim 3, characterized in that the grooves (9) in the segment cutting elements (2) and the spring (8) are formed on the periphery of the circular carrier body (1). 5. Circular knife according to claims 1 and 2, characterized in that segment cutting elements (2) and one- or two-part carrier body (1 or 1.1/1.2) are attached in an overlapping manner (11/12) by riveting or pinning (3) and/or gluing (6).