GB2308085A

GB2308085A - Apparatus for cutting strips from a moving web

Info

Publication number: GB2308085A
Application number: GB9625762A
Authority: GB
Inventors: Steffen Kahl; Albrecht Roehrdanz
Original assignee: Robert Bosch GmbH
Current assignee: Robert Bosch GmbH
Priority date: 1995-12-12
Filing date: 1996-12-11
Publication date: 1997-06-18
Anticipated expiration: 2016-12-11
Also published as: DE19546255C1; GB9625762D0; ITMI962589A1; IT1286472B1; CH691356A5; GB2308085B; ITMI962589A0; JPH09183010A

Description

1 Device for cutting packaging strips from a continuously fed web of

material 2308085 The invention proceeds from a device for cutting packaging strips from a continuously fed web of material according to the preamble of claim 1. The operating costs of such known devices are substantially determined by the relatively fast-wearing cutting knives. It is known to manufacture the cutting knives from hard metal in order to extend their service life. It is further known, e.g. from DE 24 05 860 B2, to use on a rotating shaft a bar-shaped cutting knife with a square area of cross section, which has four cutting edges. The turnmig ability of the cutting knife makes it possible to achieve a longer service life of the cuttmg knife.

The device according to the invention for cutting packaging strips from a continuously fed web of material having the characterizing features of claim 1 has the advantage that the operating costs may be additionally reduced in particular by minimizing the volumes of the cutting knives. Minimizmg the volumes of the cutting knives is achieved by the design of the structural parts of the device which carry and positively receive the cutting knives. It is particularly advantageous that both cutting knives, as a result of their square area of cross section, may by virtue of appropriate turning be used a plurality of times. which extends the service life of the cutting knives and hence additionally reduces the operating costs.

Further advantages and advantageous developments of the device according to the invention for cutting packaging strips from a continuously fed web of material are indicated in the sub-claims and in the description. A further reduction in the current operating costs by virtue of lower costs for manufacturing and storing the cutting knives may be achieved when both cutting knives are identical in construction. The service life of the cutting knives may be additionally extended by the use of hard metals for the cutting knives. A further

7 2 advantage is that, by virtue of the substantially cylindrical lateral surface of the rotating shaf said shaft simultaneously forms a supporting surface and guide for the web of material so that the device is operationally extremely reliable.

An embodiment of the invention is illustrated in the drawings and explained in detail in the following description. Of the drawings, Figure 1 is a front view, partially mi section, of a device for cutting packaging strips from a continuously fed web of material, Figure 2 a section in the plane 11-11 of Figure 1, and Figure 3 a cross section of a detail of the knife fastening.

The device 10 for cutting packaging strips 11 from a continuously fed web of material 12 is part of an installation (not shown) for manufacturing and packaging sweets. The web of material 12 is preferably supplied in roll form and fe(L for example, by means of a driven pair of feed rollers 13, 14 to the device 10. After cutting of the packaging strips 11 by the device 10, the individual packaging strips 11 are fed by means of known devices (not shown) to the sweets for wrapping.

The device 10 comprises a substantially plate-like carrier 16 disposed at right angles to the feed direction X of the web of material 12. Extending on the carrier 16 at the side directed towards the web of material 12 is a step-like extension 17, which is formed over the width of the web of material 12 and has a flat surface 18 lying at an angle of about 45' relative to the feed direction X of the web of material 12.

A first bar-like cutting knife 20 having a square area of cross section rests with one side surface flat on the surface 18. The side length of the area of cross section of the first cutting knife 20 is, for example, 8 mm. The first cutting knife 20 is preferably made of hard metal, with all four longitudinal edges being designed as cutting edges 21ato 21d. A stiffening rail 22 is used to fix the first cutting knife 20 on the surface 18 of the cam er 16.

The stiffening rail 22 is screwed to the surface 18 of the carrier 16 by means of, for example, four screws 24 which are disposed at regular Mitervals at right angles to the surface 18 of the carrier 17 in a countersunk manner in the stiffening rail 22. For receiving the first cutting knife 20, the stiffening rail 22 has two stop faces 26, 27 arranged at right angles to one another and adapted to the corresponding side surfaces of the first cuffing knife 20. The one stop face 26 extends almost up to the cutting edge 21a of the first cutting knife 20. This means that three of the four side surfaces of the first cutting knife 20 are at least partially overlapped by the surface 18 and the stop faces 26, 27 of the stiffening rail 22. The first cutting knife 20 is therefore almost positively enclosed by the carrier 16 and the stiffening rail 22. An important factor for the dimensioning of the first cutting knife 20, as well as of the carrier 16 and the stiffening rail 22, is that the strength or stiffness required for operation of the device 10 is supplied almost exclusively by the carrier 16 and its extension 17 as well as by the stiffenmg rail 22. The first cutting knife 20 is required to perform only the cutting function.

For precise adjustment of the position and cutting gap of the cutting edge 2 la to 2 ld of the first cutting knife 20 actually mi use, a rail 28 is formed on the carrier 16. Screwed into the rail 28 are, for example, four screws 25, which are each preferably provided with a fine-pitch thread and the undersides of which act upon the stiffening rail 22 so that, by virtue of differing reaches of the screws 25, an adjustment of the position of the stiffening rail 22 on the surface 18 of the carrier 16 is made possible.

Cooperating with the first, rigidly arranged cutting knife 20 is a second cutting knife 30 which is connected to a rotating shaft 29. The second cutting knife 30 is identical in construction to the first cutting knife 20. This means that it has the same length and area of cross section, likewise has four cutting edges 31a to 31d and is preferably made of hard metal. Theshaft291s disposed at the opposite side of the web of material 12 to the carrier 16. The shaft 29 is supported in two limbs 32, 33 disposed on the carrier 16. For non-floating support of the shaft 29 in the limbs 32, 33, an angular-contact ball bearing 34, 35 is disposed in each limb 32, 33, said angular-contact ball bearings 34, 35 being 4 braceable byrneans of a nut 37 disposed atone end 36 of the shaft 29. Disposed at the other end of the shaft 29 are a jaw clutch 3 8 for a drive (not shown) of the shaft 29 as well as a greasing nipple 39.

The shaft 29, for receivmg the second cutting knife 30. is longitudinally slit with an eccentric parting plane 40. The shaft 29 is divided by the parting plane 40 into a larger basic element 41 and a smaller auxiliary element 42. The basic element 41 and the auxiliary element 42 are connected by means of a plurality of screws 43 arranged, for example, inclined at an angle of 45' to the parting plane 40. The screw heads 44 of the screws 43 are fully countersunk in the basic element 41. A first retaining lug 45 disposed at right angles to the parting plane 40 is formed on the basic element 4 1. Approximately half of the first side surface 46a of the second cutting knife 30 is overlapped by the first retaining lug 45. The entire second side surface 46b of the second cutting knife 30 moreover rests in the region of the parting plane 40 against the basic element 4 1. A second retaining lug 47 as well as a stop face 48 disposed at right angles to the parting plane 40 are formed on the auxiliary element 42. The entire third side surface 46c of the second cutting knife 30 rests against the stop face 48 of the auxiliary element 42. Furthermore, the second retaining lug 47 overlaps approximately half of the fourth side surface 46d of the second cutting knife 30.

From the above description of the construction of the shaft 29 and of the basic element 41 and the auxiliary element 42 it is evident that the second cutting knife 3 0. with the exception of the cutting edge 3 1 a to 3 1 d actually 'm use, is embedded almost completely in the shaft 29.

An important factor for the dimensionffig of the second cutting knife 30 as well as of the basic element 41 and the auxiliary element 42 is that the strength or stiffness required for operation of the device 10 is supplied almost exclusively by the shaft 29. Thus, the second cutting knife 30 may be minimized m terms of its volume, so that merely a use of the cutting edges 3 1 a to 3 1 d is enabled, and the second cutting knife 30 may still be connected securely to the shaft 29.

The device 10 described above operates as follows:

The web of matenal 12 is fed by means of the pair of feed rollers 13. 14 continuously in feed direction X into the intake region of the device 10. At the same time, by means of a drive (not shown) the shaft 29 is set by the jaw clutch 38 in anti-clockwise rotation. Thus, upon each revolution of the shaft 29. the cutting edge 2 1 a of the first cutting knife 20 and the cutting edge 3 1 a of the second cutting knife 30 are brought once mito engagement. In accordance with the feed rate of the web of material 12 and the rotational speed of the shaft 29, a packaging strip 11 of appropriate length is therefore cut from the web of material 12.

For trouble-free operation of the device 10, it is advantageous that the screws 43, which connect the auxiliary, element 42 to the basic element 41 of the shaft 29, or their screw heads 44, are fully countersunk in the shaft 29. As a result, the lateral surface of the shaft 29 is interrupted only at the point of the cutting edge 3 la of the second cutting knife 30. The shaft 29 therefore forms, together with the underside of the stifleruing rail 22. a guide for the web of matenial 12.

6

Claims

1.

2.

3.

4

5.

Device (10) for cutting packaging strips (11) from a continuously, fed web of material (12), having a first knife (20) disposed in a stationary manner and a second knife (30) connected to a rotating shaft (29), characterized mi that both knives (20, 30) are bar-shaped with a square area of cross section, that both knives (20, 30) each have four cutting edges (2 1 a to 2 1 d; 3 1 a to 3) 1 d), that the shaft (2 9) is divided 'm two and at least partially encloses the second knife (3 0) at its side surfaces (46a to 46d), and that the first knife (20) Is embraced by a carrier element (16) and a stiffening element (22). which act at least upon three side surfaces of the first knife (20).

Device according to claim 1, characterized in that both bar-shaped knives (20, 30) have identical lengths and areas of cross section.

Device according to claim 1 or 2, characterized in that the shaft (29) has a substantially cylMidrical lateral surface which is interrupted only in the region of a cutting edge (3 1 a) of the second knife (3 0).

Device according to one of clauns 1 to 3, characterized mi that the shaft (29) has an eccentric parting plane (40) and comprises a larger basic element (41) and a smaller auxiliary element (42), which are both (41, 42) connected to one another by connection means (43).

Device according to claim 4, characterized in that the basic element (4 1) and the auxiliary element (42) each have a retaining lug (45, 47) for positively receiving the second knife (30).

7

6.

7.

8.

9.

10.

11.

Device according to one of claims 1 to 5. characterized in that at least one of the knives (20, 30) is disposed in a displaceable manner for the purpose of positional variation, in particular for adjusting the cutting gap.

Device accordmg to claim 6, characterized mi that the positional variation is effected by means of a plurality of screws (25) which act upon the first knife (20).

Device according to one of claims 1 to 7, characterized in that the shaft (29) is braced at its end faces by means of two angular-contact ball bearings (34, 35).

Device according to one of claims 1 to 8. characterized in that both knives (20, 30) are made of hard metal.

Device accordffig to one of claims 1 to 9, characterized in that the first knife (20) is fastened to a carrier ( 16), from which extend two limbs (32, 33) mi which the shaft (29) for the second knife (30) Is supported.

A device for cutting packaging strips substantially as heremi described with reference to the accompanying drawmigs.