EP3808517A1 - A cutting device, in particular a rotary cutting machine for workpieces made using plastic and / or rubber extrusion - Google Patents

Abstract

The rotary cutting machine is intended for workpieces from plastic and / or rubber extrusion and has a machine frame (1) with a rotatably drivable knife arranged on the machine frame (1) and a cutting bushing (6) detachably arranged on the machine frame (1), which has a recess extending in the longitudinal direction (7) of the cutting bush (6) for receiving a workpiece to be cut to length and which has a cutting gap extending essentially transversely thereto, through which a rotating knife can be passed. The cutting bush (6) has a number of disks arranged one behind the other, which can be formed by laser cutting or similar thermal or machining production methods.

Description

The invention relates to a cutting device, in particular a rotary cutting machine for workpieces from plastic and / or rubber extrusion.

Such machines are state-of-the-art and are used to divide elongated profiles (endless profiles) into defined length sections. The area of application is typically in the rubber and plastics industry. Machines of this type can be connected downstream of an extruder, but can also be operated outside the extrusion line from a reel, a lap bundle or a pallet. These can be hoses, pipes, or otherwise profiled workpieces. What they all have in common is that the workpiece is usually fed at a constant speed and that the machine is continuously used to cut to lengths of the same length. Such machines are state of the art and are offered, for example, by Rolf Schlicht GmbH in Reinfeld under the type designations MC-25, 40, 50, 80, 100 depending on the size of the maximum profile width to be machined.

Such a machine typically has a machine slide which forms part of the machine frame and in which a cutting bush is detachably arranged, which has a longitudinally extending recess for receiving the workpiece to be cut and its inner contour to the cross-sectional contour of the workpiece is adjusted. In the middle, that is to say halfway along the length of the cutting bush, a cutting gap is provided which penetrates at least part of the cross-section of the bush and into which a cutting knife can be inserted, which cuts through the workpiece located in the bush. The knife is arranged at the end of a lever which is seated on a driven shaft which is parallel to the cutting bush in such a way that the length of the separated workpiece section is determined by the workpiece speed feed and the rotational speed of the shaft and thus of the knife.

Such machines have proven themselves and are particularly suitable for cutting profiles of plastic and / or rubber extrusion to length. These are typically, but not necessarily, workpieces that are flexible and bendable. In order to achieve a clean, that is, smooth cut transversely to the longitudinal axis of the workpiece with such materials, the cutting bush is designed so that its inner contour corresponds to the outer contour of the workpiece and surrounds it with little play. This ensures that when the knife penetrates the cutting gap, the workpiece cannot evade and a comparatively straight separating cut is made.

The disadvantage here, however, is that, since a separate cutting bush is required for each profile and each profile size, a high level of tooling is required. These cutting bushes, for example 40 cm long, are complex to manufacture, since the central recess, which is adapted to the cross-sectional profile of the workpiece, is formed in a complex manner by spark erosion. Such processing is tedious and expensive and also has the disadvantage that the inside of the recess is difficult to access with a tool due to its length, and in practice is not accessible at all, especially with small profile cross-sections.

Against this background, the present invention is based on the object of improving a cutting device of the generic type.

This object is achieved according to the invention by a cutting device having the features specified in claim 1. Advantageous embodiments of the invention are specified in the subclaims, the following description and the drawings. The essential improvement takes place in that a cutting bush with the features specified in claim 15 is used.

The cutting device according to the invention, in particular a rotary cutting machine for workpieces from plastic and / or rubber extrusion, has a machine frame, a knife arranged on the machine frame and rotatably drivable, a cutting bush arranged on the machine frame with a recess extending in the longitudinal direction of the cutting bush for receiving a workpiece to be cut to length , wherein the cutting bush has a cutting gap which extends essentially transversely thereto and is provided and intended for passing the knife through. According to the invention, the cutting bush has a plurality of discs arranged one behind the other.

The basic idea of the present invention is to improve and simplify the construction of the cutting bush for the cutting device, so that on the one hand the production of the cutting bush is more cost-effective and, in a further development, an improved cutting result is also achieved. According to the invention, the cutting bush is not formed in one piece as in the prior art by a turned part machined by spark erosion, but is constructed in slices, the thickness of the disks being dimensioned so that they are as cost-effective as possible can be manufactured and processed. The wafers are typically produced, that is, the external contour is produced and the internal contour of the recess adapted to the workpiece is produced by burning, in particular laser cutting or milling. In principle, this shaping could also be done by punching, but this is currently unlikely to be economical due to the punching tool costs. To connect the disks to one another, screw connections can advantageously be used, which are described in detail below. The recesses or bores required in this respect can also be formed by cutting, but also by machining or in another suitable manner. This slice-by-slice construction of the cutting bush also has numerous other advantages, such as the ability to coat the recess, possible fixation of the workpiece during the cutting process, and much more.

For the purposes of the invention, a disk is to be understood as a tool part whose thickness, that is to say whose extension in the longitudinal direction of the cutting bushing is significantly smaller, typically many times smaller than in the transverse direction.

Basically, the cutting gap extends transversely to the longitudinal direction of the cutting bush and is delimited by two adjacent disks. However, the present invention is not limited to transverse cutting gaps; in the sense of the invention, cutting gaps can also be transverse, which are arranged at an angle, for example in order to cut trapezoidal workpiece sections. It goes without saying that a corresponding angle must then be formed between the axis of rotation of the shaft of the knife and the longitudinal axis of the cutting bush.

The disks, at least some of these disks, advantageously have recesses adapted to the cross-sectional contour of the workpiece to be cut and are arranged with respect to one another in such a way that their recesses are aligned with one another. In this way, a cutting bush can be built up using a plurality of disks with correspondingly contoured recesses, which essentially corresponds to the properties of a cutting bush according to the prior art, but can be produced cost-effectively and has further advantages listed below.

Advantageously, the cutting bush is not made up of such disks over its entire length, but is provided at the ends with end pieces which typically have a significantly greater thickness than the disks and which are not necessarily provided with a cross-sectional contour like the disks, but, for example, with a somewhat larger one circular contour, so that these end pieces are largely independent of the profile and can therefore be used for a large number of profiles to be machined on the machine. These end pieces are used to fasten the cutting bush in the machine slide and typically have a circular outer contour with which they can be clamped in the corresponding receptacles in the slide.

The end pieces can also be designed in the contour of the workpiece.

It is advantageous if the cutting bushes made up of a number of disks are made up of two structural units which are aligned with one another in the installation position and which are each releasably connected to one another in a form-fitting manner, preferably by means of threaded bolts, i.e. screws, threaded rods or the like. According to a further development of the invention, it is provided to arrange at least one disk of the cutting bush so that it can move to a limited extent in the transverse direction and to bring it into operative connection with a rotatably arranged cam, which deflects the disk against a spring force in the transverse direction when it rests on the outer circumference of the disk, in order to fix the workpiece during the cutting process. Such a fixation of the workpiece during the cutting process can in principle also be provided independently of the disk-shaped structure of the cutting bush, but can be implemented in a particularly advantageous manner with such a structure. The movability in the transverse direction can take place by a pivoting movement or a sliding movement and results in the contoured recess being brought out of alignment with the stack of discs into a position slightly offset from it, whereby the workpiece is clamped to the immediately adjacent discs.

The cam moving the respective disk in the transverse direction does not necessarily have to be a rotatably arranged cam, but can in principle also be a cam moved by linear movement. In terms of design and process, however, it is particularly advantageous to provide a rotatable cam, since this can then be attached to the shaft of the knife that is already present and it is ensured that the movement of the cam is always synchronized with that of the knife.

This can advantageously be realized in that the knife is seated at the end of a lever arranged non-rotatably on a drive shaft, and that the drive shaft also carries the at least one cam for controlling a disc in the transverse direction. It is structurally favorable if the cam is arranged next to the knife on the same lever, preferably at a distance so that it is not the disks directly adjoining the cutting gap, but rather the disks arranged next to it, that are acted upon. It is true that one that can be moved transversely to a limited extent is sufficient to fix the workpiece Disc made of, but it is particularly advantageous to provide two discs, provided on both sides of the cutting gap, with limited transverse movement, since this fixes the workpiece on both sides of the cutting gap, thereby ensuring a particularly straight and even cut. If, which is advantageous, a cutting bush is constructed from two structural units, then it is advantageous to assemble each structural unit with two or more, preferably three threaded bolts, which are fastened in threaded bores in a disc adjacent to the cutting gap on the one hand and on the end piece on the other. The disks in between are thus clamped and held between these two components.

In order to ensure the limited transverse mobility of the panes intended for clamping, it is necessary that they are not clamped in the stack, but rather are arranged to be movable relative to the adjacent panes. For this purpose, it is provided according to a further development of the invention that the threaded bolts are designed as bearings in the area of the limited moveable disk, here a bearing is typically screwed onto the threaded bolt, which is incorporated within the correspondingly larger dimensioned bores of this limited moveable disk.

In principle, the disk, which is movable to a limited extent, can be arranged to be movable in any desired manner transversely to the longitudinal axis of the cutting bush, but it is particularly advantageous if it is arranged to be pivotable. For this purpose, the disk, which is movable to a limited extent, has a circular recess for receiving a bolt as the axis of rotation and at least one, but preferably two further elongated recesses, each for receiving another bolt for guidance. The slot-shaped recesses are arranged in such a way that they form the slot-shaped recesses when the disk, which can be moved to a limited extent, is pivoted about the axis of rotation of the one bolt Move across the other bolts and guide the disc in this way.

It is particularly favorable in terms of manufacturing technology if the recess provided for receiving the workpiece is formed by laser cutting. It goes without saying that the other recesses and the disk itself can also be formed by laser cutting, for example from sheet steel. This is advantageous in terms of production technology, since on the one hand the costs are significantly lower compared to eroding, but on the other hand a sufficient surface quality of the cut surfaces is guaranteed.

Alternatively, the recesses can also be produced by other thermal or machining processes.

The inventive design of the cutting bush using several disks makes it possible and advantageous to provide the recess in the disk with a coating, be it an abrasive coating or a coating that promotes transport of the workpiece, depending on the application. This is also possible with small recesses, since the interior of the recess is easily accessible due to the comparatively small thickness of the panes.

Fig. 1

in stark schematisierter perspektivischer Darstellung eine Rotationsablängmaschine,

Fig. 2

in vergrößerter Darstellung eine Draufsicht auf den Schlitten der Maschine,

Fig.3

einen Schnitt längs der Schnittlinie III-III in Fig. 2,

Fig. 4

in perspektivischer Darstellung den Aufbau der Schneidbuchse mit damit in Eingriff stehendem Schneidmesser,

Fig. 5

die Anordnung gemäß Fig. 4 in Ansicht von oben.

Fig. 6

eine Seitenansicht der Fig. 5,

Fig. 7

einen Schnitt längs der Schnittlinie VII-VII in Fig. 5,

Fig. 8

in schematischer Explosionsdarstellung den Aufbau der Schneidbuchse,

Fig. 9

in vergrößerter schematischer Darstellung ähnlich den Fig. 4 und 6 das Wirkprinzip zwischen Klemm- und Schneidfunktion und

Fig. 10

in Explosionsdarstellung den Aufbau einer Baueinheit der Schneidbuchse.

The invention is explained in more detail below with reference to an embodiment of a rotary cutting machine. Show it:

Fig. 1

a highly schematic perspective illustration of a rotary cutting machine,

Fig. 2

an enlarged view of a top view of the carriage of the machine,

Fig. 3

a section along the section line III-III in Fig. 2 ,

Fig. 4

a perspective view of the structure of the cutting bush with the cutting knife engaged therewith,

Fig. 5

the arrangement according to Fig. 4 in top view.

Fig. 6

a side view of the Fig. 5 ,

Fig. 7

a section along the section line VII-VII in Fig. 5 ,

Fig. 8

a schematic exploded view of the construction of the cutting bush,

Fig. 9

in an enlarged schematic illustration similar to Figures 4 and 6 the operating principle between clamping and cutting function and

Fig. 10

an exploded view of the structure of a unit of the cutting bush.

In the Fig. 1 The rotary cutting machine shown has a machine frame 1, which has a closed, floor-standing, cuboidal body with a cutting carriage 2 displaceably arranged thereon. The machine is controlled via a column-shaped control panel 3 protruding from the body. The structure of the cutting carriage is based on the Figs. 2 and 3 shown in detail. The cutting carriage is designed as a box-shaped component and has two clamping devices 5 on its side walls 2, each of which has a cylindrical receptacle, the cylindrical receptacles being aligned with one another and being provided for receiving a cutting bush 6, which is fixed with the clamping devices 5 on the cutting carriage 2 and can be aligned. The cutting bush 6, which has an essentially cylindrical design, extends through the cutting carriage 2, its longitudinal axis 7 is arranged parallel to the axis of rotation 8 of a shaft 9 which is rotatably mounted within the cutting carriage 2 and which can be driven by an electric motor 10. A lever 11 is non-rotatably seated on the shaft 9, at one end of which a cutting knife 12 and at the other end of which a counterweight 13 is arranged. The arrangement is such that when the shaft 9 rotates, the cutting knife 12 is moved through a cutting gap 14 in the center of the cutting bush 6 and thereby cuts through a workpiece guided in the cutting bush 6.

The cutting bush 6 has an end piece 15 which has a flange-like section 16 with which this end piece 15 rests axially on the associated clamping device 5. The other end piece 17 has a substantially cylindrical shape. Both end pieces 15 and 17 have a circular recess 18 which is independent of the workpiece and serves to safely insert and remove the workpiece from the tool.

In this embodiment, 24 disks 20 are incorporated between the end pieces 15 and 17. The disks 20a adjoining the end pieces 15 and 17 are essentially circular, whereas the disks 20b, 20c and 20d adjoining the cutting gap 14 are flattened towards the shaft 9. All discs 20 have a contoured recess 21 (only in the Figures 9 and 10 shown), which in their contour corresponds to the to be machined, that is, corresponds to the workpiece to be cut to length, only the recesses 18 in the end pieces are circular and dimensioned independently of the workpiece.

The end pieces 15 and 17 and the disks 20 integrated between them are all arranged in such a way that the contoured recesses 21 are aligned with one another and these in turn are aligned with the recesses 18.

The cutting bush 6 consists of two structural units, namely a first structural unit 22 consisting of the end piece 15, adjoining nine disks 20a, an adjoining stationary, circumferentially flattened disk 20b, an adjoining, limitedly movable, circumferentially flattened disk 20c and one attached to it subsequent solid, circumferentially flattened disk 20d. The second structural unit 23 is constructed analogously starting from the end piece 17 with adjoining nine circular disks 20a, an adjoining flattened stationary disk 20b, an adjoining flattened disk 20c with limited mobility and a stationary flattened disk 20d.

Each structural unit 22, 23 has three threaded rods 24 which are received with their inwardly directed ends in corresponding threaded bores 25 in the disks 20d. Bearings 26, which are arranged in corresponding recesses in the disks 20c, sit on these threaded rods. The middle threaded rod 24 in the figures forms with the bearing 26 a pivot bearing for a disk 20c that can move to a limited extent, which has an elongated hole 27 in the area of the two other threaded rods 24, the elongated holes being oriented as in FIG Fig. 7 recognizable that the in Fig. 7 shown disc 20c counter to the force of a spring 28 clockwise can be pivoted a little so that the central, contoured recess 21 in this disk is no longer aligned with the recesses 21 of the adjacent disks and can thus exert a clamping force on the workpiece lying in the recess 21.

The adjoining disks 20b and 20a are fastened there by means of the threaded rods, which also pass through the end pieces 15 and 17 (only in Fig. 8 shown) nuts 29 set. These threaded rods 24 ensure that the structural units 22 and 23 are arranged in the intended position in which the recess 21 of the disks 20 and the recess 18 in the end pieces 15 and 17 are aligned with one another.

A small offset can be achieved by the pivoting mobility of the disks 20c, which can be controlled by cams 30, which are arranged at a distance next to the cutting knife 12 on the lever 11 that when the shaft 9 rotates immediately before the knife 12 penetrates the cutting gap 14 begins to cut, the limited movable disks 20c are pivoted a little so that the workpiece located in the cutting bush 6 is briefly clamped on both sides of the cutting gap 14. As soon as the knife has penetrated the workpiece and thus cut to length, the cams 30 also disengage, the pivotable disks 20c return to their starting position due to spring force and release the longitudinal movement of the workpiece through the cutting bush 6. If the shaft 9 is driven, for example, at 900 revolutions per minute, the tool is clamped for a few milliseconds, which corresponds, for example, to a feed in the 1/10 millimeter range. This discontinuity can easily be compensated for in the feed section, which is 400 millimeters for example, between the extruder outlet and the machine inlet become. The clamping of the workpiece on both sides of the cutting gap, on the other hand, results in a smooth and precise cut.

In the Figures 4 to 8 the recesses of the cutting bush are shown as circular. Based on Figures 9 and 10 is shown how such a cutting bush 6 looks like when, for example, a workpiece is to be cut to length, which has an L-shaped outer contour. Clearly visible in Fig. 10 is that the disks 20 have contoured recesses 21, whereas a circular recess is provided in the end piece 15.

Based on Fig. 9 is visible in detail how, for example, the circumferential flattening of a limited moveable flattened disk 20c in connection with the cam 30 can look in order to achieve the desired clamping effect. It is also clearly visible that the clamping cam 30 is arranged in such a way that the clamping effect occurs before the cutting knife 12 comes into contact with the workpiece and is held in this position until the cutting knife 12 has completely severed the workpiece.

List of reference symbols

1

Machine frame

2

Cutting slide

3

Control panel

4th

Side walls of 2

5

Clamping device

6th

Cutting bush

7th

Longitudinal axis of 6

8th

Axis of rotation

9

wave

10

engine

11

lever

12th

Cutting knife

13th

Counterweight

14th

Cutting gap

15th

End piece

16

flange-like section

17th

End piece

18th

Recess in the end pieces

20th

Discs

20a

cylindrical discs

20b

fixed flattened disks

20c

Flattened discs with limited mobility

20d

Threaded flattened washers

21

Recesses in the discs

22nd

first unit

23

second unit

24

Threaded rods

25th

Threaded holes in the washers 20d

26th

warehouse

27

Long holes in the disks 20c

28

Spring in washer 20c

29

Nuts

30th

cam

Claims (15)

Cutting device, in particular rotary cutting machine for workpieces from plastic and / or rubber extrusion, with a machine frame (1), with a knife (12) arranged on the machine frame (1) and rotatably drivable, with a cutting bush (6) arranged on the machine frame (1) , with a recess (18, 21) extending in the longitudinal direction (7) of the cutting bush (6) for receiving a workpiece to be cut to length and with a cutting gap (14) extending essentially transversely thereto for guiding the knife (12) through, characterized in that, that the cutting bush (6) has a number of discs (20) arranged one behind the other. Cutting device according to claim 1, characterized in that the disks (20) each have a recess (21) adapted to the cross-sectional contour of the workpiece to be cut and are arranged such that their recesses (21) are aligned with one another. Cutting device according to claim 1 or 2, characterized in that the cutting bush (6) is provided with an end piece (15, 17) at each end, the cutting bush (6) with the end pieces (15, 17) being fixed in the machine frame. Cutting device according to claim 3, characterized in that the end pieces (15, 17) have recesses (18) which are not adapted to the workpiece contour and which surround the workpiece at least at sections of its circumference at a distance. Cutting device according to one of the preceding claims, characterized in that the cutting bush (6) is constructed from two structural units (22, 23) which are aligned with one another in the installation position and which are each detachably connected in a form-fitting manner, preferably by threaded bolts (24). Cutting device according to one of the preceding claims, characterized in that at least one disc (20c) of the cutting bush (6) is arranged to be movable to a limited extent in the transverse direction and is in operative connection with a rotatably arranged cam (30), which the disc (20c) is in contact with The outer circumference of the disc (20c) deflects against spring force in the transverse direction for the purpose of fixing the workpiece during the cutting process. Cutting device according to Claim 6, characterized in that the cutting bush (6) has two disks (20c) which can be moved to a limited extent in the transverse direction, each of which is assigned a rotatable cam (30), the disks (20c) on both sides of the cutting gap (14). and are preferably separated from the cutting gap (14) by at least one further disk (20d). Cutting device according to one of claims 6 or 7, characterized in that the knife (12) is seated at the end of a lever (11) arranged non-rotatably on a drive shaft (9), the drive shaft (9) also to the at least one cam (30) Control of a disc (20c) carries in the transverse direction. Cutting device according to one of the preceding claims 6 to 8, characterized in that the cam or cams (30) next to the knife 812) are arranged on the same lever (11). Cutting device according to one of the preceding claims, characterized in that each structural unit (22, 23) preferably has three threaded bolts (24) which are inserted into threaded bores (25) of a disc (20d) adjacent to the cutting gap (14) on the one hand and on the end piece (15 , 17) on the other hand are attached. Cutting device according to Claim 10, characterized in that the threaded bolts (24) are designed as bearings (26) in the area of the disk which can be moved to a limited extent. Cutting device according to one of the preceding claims, characterized in that the disc (20c), which can move to a limited extent, has a circular recess for receiving a bolt (24) as the axis of rotation and at least one, preferably two further elongated recesses (27) each for receiving another bolt (24) ) for guidance Cutting device according to one of the preceding claims, characterized in that the recess (21) provided for receiving the workpiece is formed in a disk (20) by laser cutting. Cutting device according to one of the preceding claims, characterized in that the recess (21) provided for receiving the workpiece is coated in a disk (20). Cutting bush for a cutting machine according to one of the preceding claims, which has a number of discs (20) arranged one behind the other and which can additionally have features from one or more of the preceding claims

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