DE2061703A1 - Roll cutting device - Google Patents

Description

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DIPI.-ING. WrLFRID RAECK PATENT Attorney 9 Π R 1 7 Π ^

7STUTTGARTi, MOSERSTRASSE 8 TELEFON (07Π) 244003 ^ ^ ^ '' ^UJ

December 14, 1970 / F - BE 247 -

BELOIT CORPORATION, 1st St. Lawrence Avenue, Beloit, Wisconsin 535 11,

United States

Roll cutting device

The invention relates to cutting devices to a to cut moving material web or material sheet continuously lengthways and relates in detail to a roll cutting device, which automatically keeps itself in a sharpened state during operation.

A preferred embodiment of the invention finds application in the continuous longitudinal cutting of moving paper webs, whereby other material, for example extruded plastic film, could also be processed successfully. The paper will usually cut up after leaving the paper machine when wrapping. Usually several cutting devices are arranged on the input side across the width of a winding stand. Rolls produced on the paper machine with a diameter of e.g. 152 cm and a width of more than 762 cm, are removed from the rewind stand at the end of the paper machine

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and when wrapping (rewinding) over the slitting devices guided and wound up in strips of different widths. Since paper machines run day and night, we will the winding and rewinding is also carried out in an uninterrupted working process. When the knives of the cutters become dull, the tearing process that then takes place creates a heavy build-up of dust and an undesirable roughened surface Edge of the shredded paper, Replacing that has become dull Knife is necessary to avoid dust formation and irregular paper edges, but on the other hand it is time consuming, laborious and associated with effort or loss of time. For these reasons, so far any improvement is necessary to increase The lifespan of slitter winder has been enthusiastically received by the industry, and taken for granted It would be highly desirable to have a rotary cutter whose cutting blades have a long life and are durable would automatically keep this time in a sharpened state. So far, however, this goal has not been achieved.

There are cutting knives known, which are during the cutting process even sharpening (honing), but after a long time Operating time the efficiency drops, although the upper and lower cutting blades often remain razor-sharp. In this design, the upper cutting knife is located vertically above the lower cutting knife, with the cutting edges overlap in a vertical plane. The axes of rotation of the two cutting blades extend in the same or parallel vertical planes and in parallel horizontal planes. The interaction of the upper and lower circular knives in the overlapping area leads to the fact that when wear occurs the area of contact grows rapidly. Although the interacting edges are often sharp, it has been found that pressure and wear of the lower circular knife on the inner circumference of the upper circular knife can lead to a gap between the inner edge of the upper and lower circular knife opens. This gap can sometimes be so wide or large,

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that the material or paper web running through is no longer cut at all.

Major improvements in the design of slitter winder the applicant has indicated in US Patents 3 ^ 59,086 and j5,465 6j51. The ones proposed therein Action was based on the knowledge that

(1) The greatest possible sharpness can be achieved by making a point of contact by placing the upper circular blade around vertical axes can be tilted or adjusted and

(2) that this point of contact could be maintained and thus the service life of the cutting device could be extended, if üie flat radial contact surfaces of the upper circular knives be replaced by relatively thin ring-shaped lips that are literally are arranged on the outer periphery of these components, so that the Sehneidvorgang through the initial point contact of the radially outermost edges of the two engaging lips takes place. By the advocates of those endowed with such lips Cutting knives had recognized the theoretically perfect construction of an actual cutting point, became the circular knife design provided with lips to maintain this Point of contact or point of contact also in further developments followed up. In this context, the outer surface of at least one lip was made very hard on the assumption that that the point of contact is at the intersection between the slowly wearing, thin, harder outer layer and the other component can be retained.

Although the known proposals within the prior art have brought considerable theoretical progress with them, they have not proven themselves in practice to the extent predicted. So far, however, the relationships that explain the concept of maintaining the point of contact were not fully known, so that " it was not possible to understand the basic theory either; ·: u Verl.es-

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clean and perfect. There is thus a need for further improvements and port steps in the field of round knife with thin lips to make better use of this design «

The object of the present invention is to provide a rotary cutting device which, during the continuous '' Slitting a moving web of material is able to keep itself in a permanent sharpened state, to avoid frequent changing of the cutting blades. In doing so, taking into account the structural strength and the shape of the lips, the maximum possible gap between the circular knives at the cutting point is kept as small as possible will. Furthermore, according to the invention, a basis for the design and computation of lipped cutting knives to construct the lips so that the opening at the cutting point of the lips and the rearward displacement the actual contact area from the original The point of intersection from eo remains as small as possible and at the same time takes into account the structural requirements of the lip. The thickness of the lip should be related to the amount of overlap the cutting knife must be dimensioned so that an optimal balance between lip thickness and the efficiency of the cutting process is achieved.

In contrast to the known roll cutting devices, the present invention is based on the knowledge that theoretically Desired point contact of the two circular knives is not achievable in practice and is therefore a different route must be in order to arrive at a slitter winder with optimal operating characteristics.

Sin so-called "point cut" is therefore a theoretical perfect one

Solution »well auf <?;!. <? In this way the paper is slit without first biting or in any way ^r -Ar ..:}) eV: 'M fibers of the paper vtirö otter ν one in ""

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other to be separated. When cutting through all fibers the result is a perfect cutting process, whereas separated and crushed fibers lead to the formation of dust, which on the Area of paper cutting poses the biggest problem. Minaus are brought about by those who have been released from their association and crushed paper fibers gave the impression of shredded, irregular cutting edges. The same effect can be widely observed when one compares an edge of paper cut with scissors with the edge that has been cut by tearing it of the paper is created. In practice, however, point consonance cannot be maintained; rather, they are irregular and torn edges of the severed paper webs and the formation of dust the evidence that the cutting edges are dull will.

Research has shown that the dulling of a rotary cutter not only due to the loss of sharpness of the individual circular knives, but also to the Shape that the components take on during their wear and tear »The edges that are in engagement with one another, which initially consist of sharp corners, will during their wear and tear conical. Once the surfaces on both cutting knives are worn, the point of contact moves away from the original one Cutting point so that the sons oath finally takes place on a limited contact area and no longer at one point of contact. As the area of contact moves away from the original cutting point, separate the cutting knives from each other * i.e. they "open" laterally at the point where the point of contact originally existed. The location of the original point of contact for the sake of simplicity is hereinafter referred to as "point of view" Then the statement applies that the cutting point "opens" as the knife progresses, The Wear causes the actual cutting area to move further and further to Uok and the cutting point to always move

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more opens until the opening is big enough for you to cooperate Round knives no longer have any cutting effect at all.

After a certain rearward displacement of the cutting area has occurred due to wear, this becomes the cutting zone moved paper in first from the ones at the cutting point below Spaced components torn. This tearing displaces and crushes pasern, creating two tearing edges and dust » One of these tear edges is cut clean if it comes to the cutting or contacting surface, whereby even more dust is generated, while the other edge remains irregular or roughened. Finally, she progresses Wear continues until the cutting point has opened so far that no more separating process takes place at all »If you try to separate paper when the edges forming the point of view stand too far apart from one another, the same conditions occur as if you want to operate a pair of scissors with your left hand. In both cases there is no longer any possibility to keep the theoretical cutting point in contact, a clean cut being impossible because of a folding process takes place before the opening approaches the dike of the paper "

In contrast to the well-known proposals which focused on Maintaining the point of contact wherever the two cutting edges might come together is up to the present Invention is based on the knowledge that the best cutting process is achieved when the opening or width of the Quickly keep points as small as possible. Since the cutting point opening is directly related to the distance, about dlo the actual cutting surface is different from the original If the cutting point is shifted backwards, thin lips are used and sized to accommodate the backward shifting of the contact surface from the original point of intersection even after the thin lips have worn off considerably.

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Theoretically, the best results are achieved with the thinnest (side) lip possible. In this case, however, lies a lower limit value for a still flawless cutting process after the knife has been worn down below the structural one Strength of the lip, i.e. the forces that occur during operation can no longer be absorbed by the lip. About that in addition, it has been found that the optimal lip thickness is related to the amount of overlap of the two circular knives, this amount of overlap also being referred to as "penetration" will. If the lip thickness is too small for a given amount of overlap, the lips will have too much twist and turn Frictional force exerted, which would tear the paper.

In a preferred embodiment of the invention, has the lip has a uniform hardness over its entire thickness in the ralial direction. On the other hand, it is also possible to use the lips to be carried out with a certain radial thickness, and to provide a very thin hardened outer layer. The two hardened Layers would then be considered the thinnest possible and possibly even the lips that work with the best results work. At the moment, however, the production of cutting knives is preparing even greater difficulties if hardened layers are to be provided on your lips, which during the operation of the rotary cutter maintain their structural strength.

In using the preferred embodiment consisting of a set of knife parts each having a thin lip of uniform hardness throughout its radial thickness and an amount of overlap where the entire thickness of the upper lip passes below the entire thickness of the lower lip , the overlap of the two lips in the side view consists of two rhombuses or better dragon squares (deltoids), Since both cutting knives are also arranged or positioned at an angle, there is only contact in the front deltoid area , in ύζη the:., ■; T '- ^ ride r, u

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senneldende paper web first arrives. Tn dor side view passes the longer diagonal of the Deltoides horizontally and di 'shorter diagonal substantially vertically. Initially, the cutting point is at the front tip of the deltoid. As the edges of the lips wear away, the actual interface moves back from the original cutting point towards the shorter perpendicular diagonal of the deltoid. The smaller the radial thickness of the lips, the smaller the deltoid that will form when worn. Accordingly, with a small deltoid, the dimension d:? For rearward displacement of the actual contact surface is smaller and therefore not possible the "viYriung ¹¹ an; ._ ■ ;;,: ■„ ■ · -, -. ■, rr;. ^ Ii before η cutting point smaller.

When using hardened outer layers !; wpr-o ^ n, these are much thinner than the lips of uniform thickness, and thus the deltoid-shaped overlap area formed by the two hardened layers is also very small. The naon ■ ύ [■ ter /> rr he following relocation of the original cutting point in;? too small diagonals of this small deitoid surface I.ül üuüxI also very small. Behind this small deitoid-like area there is a line contact between the two hardened layers and a relatively softer surface of the other component below the hardened layer.

Other features and advantages of the invention are as follows with reference to the embodiments shown in the figures explained. Show it

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l <: <■ , 2 finmDraufnlcht in PA * ment of the YC ^ ⁴ 2 »'each? according to Fig. 1, F.:.· ;. 3 is a Enda.r \ to \: according to the 'Virile'"■> - -% ^ a ^ Kndansicnt entspt -echend the arrows 4-4 in Figure 2, in '■ In Flg 2, FJ..'.. c. ■■. ■; · eil · - components according to Fig. ΐ- in G ^ Go :: u] _t , -7 torsion

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have been pivoted to reveal the plane that runs between the two circular knives and only touches it at a certain point, Pig »5 the overlap area of known circular knives, 6a and 6B sections of known cutting knives from the plane of the paper looking downwards, 7 shows, in an enlarged representation, the overlap area according to FIG. 1,

Fig. 7 /. Dimensional relationships from Fig. 7 on an enlarged scale, Fig. 8Λ and 8B new or heavily worn circular knives according to the invention corresponding to a section through the plane of the incoming material web looking downwards,
9 shows a cross section through a section of a cutting knife

according to the invention,
10 is a diagram to illustrate the operational sequence

in the case of a winder according to the invention, FIG. 11 shows a side view of another embodiment according to the invention of circular knives,

B'ig.12 an enlarged schematic representation of a section from Pig, 11,

13 shows a section along the line A-A in FIG. 12 and FIG 14 is a diagram to illustrate the mode of operation of the second embodiment according to the invention.

In Fig. 1 to 4, the relative positions of an upper circular knife 10 and a lower circular knife 11 to each other and with respect to the material web W to be cut are shown schematically. The circular knives 10 and 11 are each provided with lip sections 12 and 13, respectively. The width of the lips 12 and 12 is greatly exaggerated in FIG. 1 in order to illustrate the basic features of the invention. In a practical embodiment, the circular knives can have a diameter between approximately 20 cm to 25 cm and a lip thickness between approximately mm and 0.38 mm. The one in the vertical direction

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measured overlap or penetration of the circular knives corresponding to the dimension P in Fig. 1 is normally between about 0.75 mm to 1.5 mm.

The circular knives 10 and 11 rotate around their central axes according to the arrow directions indicated in the individual figures. The circular knives are also adjusted or edged with respect to the direction of movement of the material web W, the total angle θ formed between the two circular knives being shown in FIG. Assuming that the two side edges of both circular knives facing each other are designed to be absolutely right-angled, both circular knives touch at a single point, namely the "cutting point" CPo shows a front view in which the circular knives 10 and 11 have been pivoted counterclockwise and tilted out of the plane of the paper about a horizontal axis through the cutting point CP. In this orientation, FIG. 4 shows a single plane, which is tangent to the contact circles between the two circular knives 10 and 11 at the cutting point CP. The angle between this tangent plane to the two contact circles and a vertical line through the axis of the circular knife 11 represents the wear angle p . The basic features of the invention are described below with reference to the exaggerated schematic representations, while FIG. 9 is a proportional representation reproduces an embodiment of the invention. 9 shows a cross section which applies to both the upper circular knife 10 and the lower circular knife 11, so that the molded lip has either the reference number 12 or 13. In this particular embodiment the total thickness is the Rundnv "ssers about ^l j mm except at the outer Uniang, ie in the vicinity of the lip 12 or 13, where the thickness is only about 4.8 mm ₀ This recess serves on the circumference of the circular knife to protect the lip, which reduces the risk of breakage

V-

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is vulnerable. Theoretically, the two radial surfaces could of the circular knife should be made flat up to the circumference, and the lip could protrude outwards from there. In the present Pail, however, the lip is formed by being in a Radial surface an annular recess 26 preferred this Recess can remain open, but is used to achieve Stability to avoid accidental breakage of the lip with a relatively soft material such as plastic or the like. filled out. This plastic material plays in operation the circular knife does not matter. In the case of the circular knife shown, the axial depth of the recess 26 can be from the outer edge of the lip are 57 mm, so that the axial extent of the lip extending from the bottom of this recess is also l.57 mn amounts to.

The basic idea of the invention is further connected below with FIGS. 5 to 8 explained. Fig. 5 shows the overlap portion between a lower and an upper round sea 15 and 17 according to the prior art. These circular knives are pure cylindrical disks with absolute flat and mutually parallel radial surfaces. The drawing applies in the same way to known devices with very thick molded lips. Assuming that the round messa? 15 and 17 are inclined or inclined to one another, finds contact in a single cutting point CP with no worn edges instead, which is marked in FIG. 5 and in FIG. 6A. In Fig. 6a are the sections that possibly wear out on the Point 16 or 18 drawn in dotted instead of the hatching. In cross-section, these sections 16 and 18 each appear to be substantially triangular, as shown at 18, so that the Both circular knives finally appear as flattened truncated cones with a chamfer on the end faces. Fig. (> B shows the relative position of the two circular knives after the Absclinitte 16 and 18 have worn out. As with this device Means are provided around the two circular disks 15 and 17

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Pressing against each other in the axial direction now finds a Contact takes place along a line X borrowed from the origin Cutting point CP has moved backwards by a distance B. In addition, the circular knives 13 and 17 are in place of the original cutting point CP now by the rather considerable amount of an opening or a distance A from one another separated.

Studies have shown that this great distance A at the cutting point CP and the considerable rearward displacement B from the cutting point CT to the line X contributes to the poor operation of the rolling cutter, AEIE by dust formation and unwanted unregeIi ¹ JiKiJige and torn edges of the Papierbäinen noticeable.

7 and 8 show how, according to the invention, with the same wear value as in FIGS. 5 and 6, the formation of a blunt circular knife is avoided, Pig. "( shows the overlap section according to FIG. 1 and FIG.; A, on an enlarged scale, shows the front overlap section in the form of a dragon square or deltoid according to FIG. as well as - \ en points 2j> and 25 formed at the ends of the short diagonal of the deltoid.

According to FIGS. 8A and 8b, the circular knives 10 and 11 each contain protruding lips 12 and Γ5, respectively. The unused circular knives according to FIG. 8A touch their lips 12 and IJ at a single cutting point CT. The lips 12 and Ij5 wear out around the dotted areas 19 and 20th The axial depth of these dotted areas is the same as the axial depth of the wearing sections according to FIGS . 6k and

H 'Ή

In the Pall of the present invention, the lips wear backwards. When the section L in Fig. 8A is worn, the cutting point moves from the original cutting point CP to the line X, which is the small diagonal of the triangle in Fig. and 7A corresponds between points 23 and 25. In contrast to the prior art, however, the further wear of the dotted areas 19 and 20 takes place in a complete cut through the lips 12 and 13, so that the two circular knives 10 and 11 are pressed against each other, but the cutting point does not move further from the original cutting point CP removed than up to the point of the small diagonal between points 23 and 25. After the circular knives have worn by an amount according to FIG. 8b, - which is the same as the sections 16 and 18 in FIGS A ¹ remained much smaller than opening A at the end of the son, and also the rearward displacement B ^! has remained much smaller than the rearward displacement B in Fig. 6B. By utilizing the knowledge according to the invention for reducing the opening or the distance at the snap point and the rearward displacement of the contact point, a cutting device is created which remains sharp even after considerable wear. Since the side opening A ^{1 is} small and the rearward displacement B ^{1 is also} small, the individual fibers of the paper are gripped by the cutting device according to FIG so that dust formation and the occurrence of irregular tear edges are avoided. In addition, according to the invention, another problem that occurs according to the prior art is also eliminated. If, in known devices according to FIGS. 5 and 6, the point of contact X is shifted backwards as far as the line connecting the two axes of rotation due to wear and tear, the two circular knives no longer move relative to one another, as is the case to achieve a perfect Shear or sawing action is required, they just roll

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against each other. In contrast to this, according to the invention, the actual cutting or contact point cannot shift backwards further than up to the diagonal between the points 2J> and 25.

It is intended according to the invention that the circular knife IO and 11 are arranged freely rotatable on their shafts, so dafj they are driven directly by the material web to be cut. Of course it is like the state of the art Technology also possible to drive the circular knives 10 and 11 by suitable motors.

In a preferred embodiment of the invention, the thickness of the outer lips 12 and 13 of the circular knives, measured in the radial direction, is 0.28 mm, the material hardness being between 53 and 58 Rockwell. These values correspond with the hardest materials, with which a lip of the specified thickness can be produced and satisfy the otherwise also the requirements that the lips would in itself resistant and uniformly have _a Boi the preferred embodiment the diameter of the upper circular blade about 20.3 ^ m and that of the lower circular knife are 21.6 cm. The angle of inclination or inclination would be 1 ° and the total overlap P at "), b" 7 mm.

The aforementioned dimensions of the preferred embodiment are in no way to be regarded as restrictive, but on the other hand also cannot be changed arbitrarily; they result from certain relationships that are explained using the following tables. In both tables the angle of attack is fe 1 °. According to Table I, the diameter for the upper circular knife is 20.3 cm and for the lower circular knife 21.6 cm. According to Table II, the diameter for the lower circular knife is 20.3 cm and for the lower circular knife 26.7 cm. It must be taken into account that paper fibers have a thickness of 0.002 to 0.02 mm, 78 to 780 milliliters.

10 9 8 2 8/0211

Overlap (P) (mm)

0.65 0.65 0.65 0.65 0.65

0.87 0.87 0.8? 0.87 0.8?

1.14 1.14 1.14 1.14 1.14

1.57 ■ 1.57 1.57 1.57 1.57

Tabel

Lip thickness Son's epic Wear and tear (mm) opening (A)
(/ *) angle 0.127 0.88 7.14 0.254 4.65 8.23 0.28 6.0 8.51 0.35 7.65 8.83 0.508 48.5 14.05 0.12? 0.52 5.92 0.254 2.50 6.5 - 0.28 3.63 6.64 0.35 3.87 6.73 0.508 16.3 8.45 0.127 0.33 5.07 0.254 1.50 5.41 0.28 1.87 5.49 0.35 2.29 5.57 0.508 8.26 6.39 0.12? 0.196 4.25 0.254 0.86 4.45 0.28 1.06 4.49 0.35 1.29 4.54 0.508 4.22 4.94

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Table II

Overlap (P) lip thickness cutting point wear

( ^mm ) (mm) opening (A) angle

0.127 0.93 7.5

0.254 4.88 8.64

0.28 6.30 8.93

0.35 8.03 9.26

0.508 50.9 14.72

0.127 0.5 ^ 4 6.22

0.254 2.59 6.82

0.28 5.28 6.97

0.35 4.08 7.12

0.508 17.05 8.87

0.127 0.346 5.32

0.254 1.57 5.68

0.28 1.96 5.77

0.35 2.40 5.85

0.508 8.66 6.71

0.127 0.234 4.47

0.254 0.904 4.67

0.28 1.13 4.72

0.35 1.35 4.76

0.508 4.44 5.19

O, , 65 0. .65 0, 65 0, 65 0, 65 0, 87 0, 87 0, 87 0, 87 0, 87 1, 14th 1, 14th 1, 14th 1, 14th 1, 14th 1, 57 1, 57 1, 57 1, 57 1, 57

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As already explained, the most favorable conditions result when the cutting point opening A is kept at a minimum value. From the overview it can be seen that the larger the overlap, the smaller the cutting point opening. It can also be seen that even a small lip thickness leads to a smaller cutting point opening. Following the information, one could theoretically combine an overlap dimension of 1.57 mm with a lip thickness of 0.127 mm and then arrive at a cutting point opening of 0.196 η. In practice, however, such an arrangement is completely useless. A lip which is designed too thin in relation to the overlap dimension and also taking into account M the diameter of the circular knives would entail various disadvantages. First of all, it would wear out too quickly overall in the axial seal. Furthermore, the geometric shape of a very thin lip with respect to a large amount of overlap would lead to tearing of the paper. In addition, the geometric relationships are such that the force required to drive the circular knives and thus the torque exerted on the components would be too great.

Investigations with circular knives of various dimensions have shown in practice that the best balance between the cutting point opening, the wear rate of the lip and a soft engagement between the components 12 and 5 is achieved when the lobe thickness is about 1 / jJ of the amount of overlap amounts to. In addition, an appropriate compromise must also take into account the degree of penetration in relation to the outer diameter of the circular knife. For example, if the amount of overlap is too great, the ÜeLtold-shaped area will approach FLg. TA to a square. This means that the diagonal 2j> -.25 becomes larger and the diagonal 22 - 24 becomes smaller. As a result, the point of contact shifts more quickly from the intersection point to the line X, with the wear and tear and the torque to be applied also increasing. On the other hand , if the amount of overlap is too low, the deltoid-shaped surface according to FIG.

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stretched. This means that the diagonal 2j5 - 25 is shortened and the diagonal 22 - 24 is lengthened. This results in a greater rearward displacement B 'from the point 22 to the line X and an enlarged opening A ¹ at the cutting point 22, when using much smaller circular knives, ζ, B. with a diameter between 7 * 5 cm and 12.5 cm or much larger circular knives, e.g. between J8 cm and 50 cm in diameter, the shape and type of lip thickness and the overlap dimension must be changed according to the specified attachments.

An excessively large amount of overlap also results in disadvantages, which consist of an interruption in the web feed speed and an undesirable scraping process. A mere interruption of the web feed means that the two zorsclinittenen sections Wj_ and W ₂ (Fig. 1 to 3) are raised to the point of soldering and drop and thereby exert undesirable forces on the paper web. The scraping refers to the radial Gioitvorgang between the two circular knives. Of course, a certain scraping effect is necessary for the peeling process; However, excessive wear will result in excessive wear.

Thus it can be seen that many of the items listed in Tables I and II Relationships and combinations are useless from a practical point of view. According to Table I, the preferred Arrangement with an overlap dimension of 0.87 mm, a lip thickness of 0.28 mm and a resulting cutting point opening of 3.6 ^ u. Since this opening value is close to is at the lower end of the size range of paper fibers, it has proven itself well in practice.

For larger circular knives according to Table II, the preferred dimensions for the overlap dimension are 1.5? mm, for the lip thickness at 0.508 mm and for the cutting point opening at 4.44 "

B ¹ Ig. Fig. 10 is a graph corresponding to Fig. 7 for the preferred Table I relationships using

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an upper circular knife with a diameter of 20 cm and a lower one Round knife with a diameter of 21.6 cm. The numbers in this illustration relate to the opening values between the points and 24 (in u) if there has been wear and the contact extends to line X between points 2 ^ and 25 extends-

In summary, it can be stated that the conditions are optimal are present if the lip thickness is between 0.254 mm and 0.375 mm. is used. These values are primarily used for basic knives with a diameter of 20 cm or 21.6 cm, for which an overlap of 0.87 mm should represent the optimum value. For larger or smaller circular knives the appropriate ones would have to be used Numerical values can be extrapolated upwards or downwards.

11 to 14 show a further embodiment of the invention with which it is attempted to produce a much thinner lip, than is normally possible for a lip of uniform hardness. This is achieved by having a hardened Layer with a thickness of about 0.05 mm to 0.1 mm on the External surface of the lip is provided. Located on the circular knife 27 a lip with a hardened outer portion JO and a softer inner section J5 ^ · The lower circular knife 28 has a molded lip with a hardened outer layer 32 and a softer inner layer

According to FIG. 12, the two thin layers J> 0 and form a very small del toid-shaped overlap section with a small diagonal 44 - 46 and a large diagonal 42 - 48.Theoretically, the contact surface shifts from the original cutting point 42 backwards to the line 44 - 46. Behind this small triangle, in the meantime, the two layers j50 and 32 wear off the softer sections 36 and J54, respectively, up to points 50 and 52, which are on opposite sides of the small diagonal of the larger triangle, that of

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the entire lip portions is formed _o This Abtrag- or wear effect which exert the hard layers 30 and 32 on the softer sections 36 and 3 ^, resulting in a concave profile corresponding to Figure "13, - the outer Umfangskantenf laugh 30, 32 are, for example, by Surface hardened nitriding to make them particularly wear-resistant.

The preferred dimensions for the different surfaces in Fig. 11 to I3 are: the hardened depth of the edge surfaces 30, 31 is 0.1 mm as a value within an appropriate range between 0.05 mm and 0.38 mm; the surfaces 3 ^ * ^ 6 are 0.5mm wide, but can also be in a range between 0.25 mm and 0.635 mm wide. The axial thickness of the circular knife including the width of the outer surfaces 30, 32 6.35 mm, and the depth of radially inward from the lip directed recess is between 1/2 and 3/4 of this Thickness. The total depth of the overlap is between 0.5 mm and 5.7 mm. This ensures that the cutting point is is always in front of the connecting line of the axes of rotation in the direction of the incoming paper web, which in turn the relative movement and the avoidance of a rolling contact between the touching surfaces is guaranteed.

For circular knives with the dimensions given above, an inclination or setting angle of 0.5 ° is required for each circular knife 27, 28 preferred with respect to the direction of movement of the material web, so that a combined cutting angle of 1.0 ° between the Inside of the circular knife is created. In certain jobs, E.g. when hand trimming or trimming, the relative angle of incidence is maintained at 1.0 ° and the entire arrangement in addition to the direction of movement of the web of material Rotated +1.5 °. This is done in a direction transverse to the machine To achieve tangential force, which keeps the material web taut at the edges and excludes the formation of wrinkles.

109828/0211 BADom _QINAL

12 shows the deltoid-shaped intersection at the surfaces y \ _t 36, the intersection point 42 is at the front tip of the intersection, and the points 50, 52 represent the upper and lower intersection points, respectively. There is no contact at the intersection point 5 ^ on the back of the deltoid-shaped surface. For the preferred dimensions of 0.5 mm surface width and radii of the circular discs of 10 cm to 13 * 3 cm, the area of the deltoid-shaped overlap is

about 1.37 mm. One that presses the round disks against each other low axial force thus leads to a relatively large pressure on the contact surface, even if it is assumed that the Contact distributed over the entire intersection area, which, however, as explained below, is not the case.

The thin, wear-resistant surfaces 30, 32 intersect in a deltoid-shaped area which, although much smaller, corresponds to the intersection of the surfaces 34, 36. As can be seen from FIG. 13, the actual point of contact, after which the round disks have ground in or slightly worn, is an approximately vertical line 44-46, which connects the two opposite points of the deltoid-shaped surface formed by the intersecting outer edges 30, 32 * The intersection point 44 is formed between the inner extension of the wear-resistant surface 30 on the upper circular knife and the outer extension of the wear-resistant surface 3 ² on the lower circular knife. The intersection point 46 is formed between the corresponding outer and inner extensions of the same surfaces. The remaining point 48 of the deltoid arises from the intersection of the inner extensions of the surfaces 30, 3Ϊ2.

BE 247 -22- 7061703

Due to the inclination or inclination of the two circular knives 27, 28, the radially inner parts of the two wear-resistant surfaces 30, 32 and the surfaces 34, 36 are curved along a Worn web extending from the peripheral edges ^ O, 32 extends radially inward and axially away from the front side 42 under the influence of the hard edges of the Surfaces 30, 32, which are the relatively softer material of the Remove surfaces 34, j6 »This can be seen from Fig. 13, the a 'section on line A-A along line 50 - 52 in Fig. 12 corresponds.,

Since the circular knives rotate against each other, the contact is made between the edge surfaces 30,32 along the line 44,46. As each of the surfaces 30, 32 successively move inward and onto or against the surface of the other Moving the component, it carries material on the surfaces 34, 36 from, namely along the slightly curved path shown corresponding to FIG. 13.

The radially inner side of each surface 3 ^> 36 extends further away from the corresponding peripheral edge surface 30, 32 of the other component because the respective circular knife is at an angle of inclination or in a setting position, dio from a line 40 along the direction of movement of the Material web is removed. Accordingly, wear of contact 36 lies along the surfaces 34, in front, from the points 44, 46, - at the boundary between the wear resistant surfaces 30, 3 ² and the surfaces 34, 36, thence inwardly to points 50, on the border between the inner surfaces and the recessed sections ₀ Since each circular knife 10, L2 diverges from the point of contact in the rearward direction, the area of intersection tapers from the hard surface 30 of one component to the face 36 of the other component until it essentially touches the line along the line 46 - 52 , there

9 828/0211

the end face of the lower circular knife diverges from the cutting edge 30 of the other component - In the same way, the hard surface> 2 of the lower component overlaps with the end face J> k of the upper component, and the intersection area tapers essentially to a line contact along the Line 44-50, as the face 34 of the upper circular knife is moving away from the hard surface 32 of the lower circular knife. The radially inwardly directed rotational movement of the edge surfaces 30, 32 through the end surfaces 3 ^ j 36 leads to the formation of the concave profile on both end surfaces in their canted or inclined position.

The curved contact surfaces 30, 32, 34, 36 and the diverging The arrangement of the circular knives together cause the formation of a hollowed-out gap which is axially (perpendicular) to the direction of movement 40 of the web of material) between the overlapping portions of the wear-resistant surfaces and the end faces extends rearward in web direction 40 from point 48 to line 50-52. Between the lines 50 - 52 is'aufgrund the divergence of the circular knives is not in contact.

Using the parameters of 10 cm and 26.6 cm outside diameter for the upper and lower circular knives, a thickness of 0.1 mm for the wear-resistant surface, one face of 0.5 mm, a radial overlap of 1.57 mm and an inclination or angle of inclination of 0.5 ° for each circular knife, the gap between the surfaces, measured in the axial direction between the circular knives and perpendicular to the direction of movement Calculate 4o of the material web according to FIG. 14 in the various values which are at the same distances Points along the sides of the deltoid-shaped overlap area appear.

10 9828/0211

be 24? - 24 - 2 U G Ί 7 O 3

For the given parameters, the axial gap at the outer overlap point 42 of the wear-resistant surfaces J) O.32 is calculated to be 0.127 n, i.e. a value that is considerably smaller than the commonly occurring thicknesses of paper fibers in the range between 0.002 and 0.02 mm. For this reason, the point of intersection, which technically consists of a gap and not a point of contact, cannot generate any dust particles during the cutting process that are greater than the thickness or width of a single paper fiber. Since the fibers are thus cut and not pulled or pushed away at the cutting point, the formation of dust is reduced to a minimum.

The operation of the embodiment of the invention shown in FIGS. 11 to 14 is as follows. At the beginning of the sons' process with two new circular knives, the end faces and the plane of the hardened wear-resistant surface run perpendicular to the axis of rotation of the respective circular knife. If the circular knives are pressed against one another by suitable pretensioning devices, for example by an air bellows, and are set in rotation either by the material web itself or by a motor, the outer edges of the wear-resistant surfaces 30, J52 come together to make point contact at point 42. The material web is supported in front of and behind the circular knives by guide and drive rollers (not shown) at a height at which it is introduced horizontally into the first intersection point 42. After a certain period of time, the surface areas JO, j> 2 grind against one another and a small gap is created at point 42. As explained above, this gap does not have a negative influence on the SehneidVorgang and does not expand any larger than has been taken into account taking into account the parameters of the angle of attack, the depth of the hardened surface and the diameter of the circular knife. Has a total angle of inclination of 0.7 ° for both circular knives

-A

109828/021 1

be 24? - 25 - 2UG17 03

produced perfect results if the other parameters be kept constant - A thinner version of the wear-resistant surfaces j5O, J52, e.g. with a value of • 0.05 mnv leads to a smaller gap at point 42, if the other paratoeters are kept constant. The touch is taken along line 44-46 (the one in the preferred Embodiment is about 0.1 mm long), the line contact diverging from there outwards and backwards (Fig. 12), If by wear the contact along the Line 44-46 occurs, a plane extends between the contact points of the inner end faces and the wear-resistant edges of the two round washers, i.e. between the points 50 and 52 in Fig. 22, - This plane forms a tangent to both Circular knife at the point of contact and forms a point with the plane of the inner surface of the upper and lower circular knife. This angle is called the wear angle and applies to Testimony to any circular knife chosen as a reference part. It has see that this angle of wear corresponds to the pitch angle kel is directly proportional and inversely proportional to the overlap value. For one. Cutting angle of 1 * 0 ° and an over-

© lappungsrflaß of. 1, .5T TO, the wear angle is around %% _: _%

Claims (1)

Dipl.-ing. WILFRID RAECK PATENT Attorney 2 O G 17 03 7 STUTTGART 1, MOSERSTRASSE 8 TELEPHONE (0711) 244003 BELOIT CORPORATION December 14, 1970 / B ¹ Beloit, Wisconsin, USA _ _{? l} Claims Roll cutting device for longitudinal cutting of a moving web of material with two mutually rotating Ruridmessorn, characterized in that the lower circular knife (11, 2li) has a lip (1 ^> 36) of predetermined radial thickness, on which the peripheral surface and a radial surface are arranged in an arc of a circle Form a sharp edge extending around the axis of the circular knife, and is slightly overlapped by an adjacent upper circular knife (10, 27) along a line connecting the centers of the two circular knives, the upper circular knife also having a lip (12, 54) of predetermined radial thickness has, in which the circumferential surface and a? Radial surface form a sharp edge extending in an arc around the axis of the circular knife, and that the front side in the cutting direction of the upper and lower circular knives are inclined to one another so that the two sharp edges meet at a point (CP) on the input side of the Roll cutting device (cutting, and with an axially inwardly directed wear of the sharp edges, the lips touch in a line (X) backwards from the original cutting point (CP), the thickness of the lip both for that in the direction of movement (4o) of the material web (W) measured distance between the original cutting point and the line of contact (X) as well as for the upper uren ^ Wciu of the lateral separation (A) between the two lips at the location of the original cutting point after wear and tear. 109828/0211 be 247 ~ ** ~ \\ 2Ü61703 2ο device according to claim 1, characterized in that the Thickness of each lip (12, IJ) about a third of the amount of overlap (P) between the upper and lower circular knives along the the line connecting the two centers corresponds to. 3. Apparatus according to claim 2, characterized in that the The diameter of the upper and lower circular knife (10, 11) is 20 cm and 21.6 cm, respectively, while the amount of overlap is approximately 0, δ5 mm and the lip thickness is around 0.28 mm. 4. Apparatus according to claim 2, characterized in that the Diameter of the upper and lower circular knife (10, 11) approximately 20 cm or 21.6 cm, while the overlap is at about 1.57 mm and the lip thickness is about 0.5 mm. at least 5. Apparatus according to claim 1, characterized in that / one the circular knife (10, 11) has a disk shape and its lip (12, 1>) on its outside through the outer circumference of the disk radially inner side is limited or shaped by an annular recess (26) in the radial surface. 6. Apparatus according to claim 5 * characterized in that the Recess is filled with plastic material. 7. Apparatus according to claim 1, characterized in that ■ "" the radial thickness of the lip is between 0.25 mm and 0.158 mm . 8. Apparatus according to claim 7, characterized in that the lip turns from the sharp edge in the axial direction extends inwardly about 1.57 mm. 10 9 8 2 8/0211 9. Apparatus according to claim 8, characterized. That the radial surface of the disc opposite to the radial surface bearing the lip is substantially flat, and that the sharp edge of the lip in the axial direction from the flat surface a smaller distance than a central part of the disc. 10. Apparatus according to claim 7 *, characterized in that the angle of inclination or angle of attack (θ) between the upper and lower circular knife (10, 11) is between 0.7 and 1.0. 11. The device according to claim 1, characterized in that the lip is made of a material over its entire radial thickness there is considerable uniform hardness. 12ο device according to claim 11, characterized in that the lip (27) has a radially inner portion (3 ^) with a has a certain hardness and an outer layer (30) of substantially greater hardness, the outer layer about 0.05 mm thick and the inner section a thickness between 0.38 mm and 0.6 ^ 5 mm. 13. Device according to one of the preceding claims, characterized characterized in that a circular knife for use in conjunction with a second cutting element has a circular outer Section with an outer ring-shaped hardened carp surface (30) and one radially inward thereof in a predetermined radial Length arranged side face (3 ^ ·) with less Having hardness than the hardened edge surface. IM . Device according to claim 13, characterized in that the hardened edge surface (30) is wear-resistant with respect to the end surface. 109828/021 1 BS 247 - 29 - ^ QG 17 03 15. Apparatus according to claim 13, characterized in that radially inward from the face in the circular knife disc an annular axial recess (26) is provided " 16. Apparatus according to claim 13, characterized in that the hardened edge surface (30) has a thickness in the radial direction in the range between 0.05 mm. 17. The device according to claim Γ5, characterized in that the radial length of the end face (34) is between 0.38 mm and 0.64 mm. 18. Device according to one of the preceding claims, characterized characterized in that the upper circular knife (27) with its axis of rotation is arranged vertically above the axis of the lower circular knife (28) at such a distance that the corresponding lateral end faces (34, 36) overlap to an extent that is at least the combined radial dimensions corresponds to the end faces. 19. The device according to claim l8, characterized in that the inclination or angle of attack between the two circular knives is chosen so that with hardened circular knife edges with a radial thickness between 0.05 mm and 0.38 mm after their wear on the input side of the A gap is created where the original cutting point is, the width of which does not exceed 1.9 m. 20. Apparatus according to claim 18, characterized in that the angle of attack is between about 0.7 ° and about 1.0 °. 21, device according to one of the preceding claims, characterized characterized in that the material of the rear edges is hardened to a radial depth between 0.05 and 0.38 mm. 10 9 8 2 8/0211