EP3969236A1

EP3969236A1 - Device and method for cutting a plastic profiled element to length

Info

Publication number: EP3969236A1
Application number: EP21748865.9A
Authority: EP
Inventors: Jörg Dröge; Tobias Hus; Heinrich Dohmann
Original assignee: Battenfeld Cincinnati Germany GmbH
Current assignee: Battenfeld Cincinnati Germany GmbH
Priority date: 2020-08-06
Filing date: 2021-07-21
Publication date: 2022-03-23
Also published as: CN114302798B; CN114302798A; WO2022028911A1

Abstract

The invention relates to a device for severing plastic products (7), more particularly extruded plastic tubes, comprising at least a first haul-off device (4), which has at least two haul-off caterpillars (12), and a cutting unit (10), which comprises at least one cutting device (5) having at least one cutting means (15), by means of which cutting device plastic products (7) can be severed to a predefined length. According to the invention, the cutting unit (10) comprises at least one caterpillar (14) having at least one cutting tool (13); on one of the caterpillars (14), at least one tool (13) is provided; at least one cutting means (15) is disposed in the tool (13), by which cutting means the plastic product (7) can be severed; and during the cutting process, the cutting means (15) disposed within the tool (13) can be rotated around the plastic product (7) to be severed. The invention also relates to a corresponding method.

Description

Device and method for cutting a plastic profile to length

Description:

The invention relates to a device for separating plastic products, in particular extruded plastic pipes, comprising at least one first extraction device with at least two extraction caterpillars, a separating unit which comprises at least one separating device with at least one separating means, by means of which plastic products can be separated to a predetermined length, and a related device Proceedings.

So-called flying saws are usually used to cut extruded pipes to length, whereby a circular saw blade is brought up to the pipe to be cut either from below (underfloor saw), from above (plunge saw) or from the side (crosscut saw), dips into the cross-section of the pipe and cuts cut through the wall thickness in the first step. In the second step, the saw blade is guided around the pipe to cut the pipe completely to length. The pipe to be cut to length is clamped during the sawing process; the saw carriage or saw carriage then moves synchronously with the continuously running extrusion process at the extrusion speed (“flying saw”).

A large number of such devices are known in the prior art, for example DE 102013220622A1 describes a device for cutting a thick-walled extruded pipe to length, with at least one cutting tool and a receiving unit for the cutting tool, the cutting tool being movable radially to the extrusion axis and using other means the pipe to be cut to length can be rotated around it in order to cut the pipe to length, it is proposed that the receiving unit comprises two toothed racks arranged in a block, the first toothed rack being movable back and forth parallel and the second toothed rack radially to the extrusion axis and on the second toothed rack the Separating tool is arranged and the ring element can be moved via an axial drive and the penetration depth of the separating tool and the travel path can be determined by means of an adjustment unit and the receiving unit is connected to a receiving disc and a sleeve, with linear guides on the sleeve elements are arranged parallel to the extrusion axis, with at least four linear guide elements being distributed evenly around the circumference of the sleeve. The disadvantage of all of these devices is that the separating unit has to move with the extrusion speed and therefore acceleration and braking energy has to be applied.

The object of the invention is to further develop the known devices and methods in such a way that it is no longer necessary to move the separating device, so that they can work more effectively and energy is saved, and the systems can therefore be operated in a more environmentally friendly manner.

The solution to the problem with regard to the device is in connection with the preamble of claim 1, characterized in that the cutting unit comprises at least one bead with at least one cutting tool, with at least one tool being arranged on one of the beads, with at least one in the tool Separating agent is arranged by means of which the plastic products can be separated.

It is therefore proposed to arrange the tool with the separating means directly on a bead of the extraction unit for cutting to length, so that the separating tool runs with the bead during the extraction process and cuts the plastic product to length.

The separating means are advantageously arranged inside the tool and can be rotated around the plastic product to be separated during the separating process. As a result, the separating process can be completed more quickly than if the separating agent had to run through the entire cross section of the plastic product.

In a further development, it is provided that the tool is designed in such a way that it encloses the plastic product to be separated in a U-shape during the separation process. This U-shaped enclosing has the advantage that the parting agent not only engages in the plastic product at one point, but that several parting agents can carry out the parting process at the same time distributed at several points around the circumference.

According to a further development, it is provided that the cutting tool can be moved with the bead at its speed. This means that the cutting tool is firmly connected to the bead. As a result, the cutting process can be completed at take-off speed.

Another bead advantageously supports the plastic product during the cutting process. This means that during the cutting process, it is transverse to the direction of extrusion, ie radially applied separating force is counteracted, whereby excessive sagging or bending of the plastic product is avoided, which in turn contributes to improving the course of the cut on the plastic product. The plastic product is preferably fixed radially by means of the beads.

Furthermore, it is possible to arrange several cutting tools on the caterpillar. This has the advantage that more than one separating process can be carried out during one rotation of the bead.

The solution to the problem with regard to the method for separating plastic products is in connection with the preamble of claim 7, characterized in that at least one separating tool is conveyed at the peripheral speed of the bead in the direction of extrusion, with at least one separating tool cutting the plastic products during the ongoing process severed. With this device according to the invention, it is no longer necessary when cutting to perform the “classic” clamping (as is customary in the state of the art today) before and after the cutting tool.

According to a further development it is provided that the cutting process takes place in a time window in which the cutting tool arranged on the bead is in contact with the plastic product, the time window being defined by the length of the contact surface of the bead with the plastic product. The axial length of the bead, in conjunction with the take-off speed, therefore determines the time window in which the cutting process must be completed. Since the separating tool is moved at the take-off speed with the bead, the separating tool is brought out of contact with the plastic product as soon as the separating tool leaves the contact area between the bead and the surface of the plastic product.

In the drawings, a device according to the invention is shown schematically:

Figure 1 shows a typical extrusion line

Fig. 2 the units involved in the separation process

Fig. 3 is an enlargement of Figure 2

Fig. 4 section through the separating unit

Fig. 5 is an addition to Figure 2

Fig. 6 is an addition to Fig. 4 Figure 1 shows a typical extrusion line as it is used today for profile extrusion, whether for the production of window profiles or pipes. It shows an extruder 1 in which plastic is melted and is continuously fed into the extrusion die 2 for shaping. This is followed by a calibration and cooling station 3, further cooling stations can be used depending on the profile. After the cooling stations, a first extraction unit 4 follows. In order to cut the endless profiles 7 to the desired length, a separating device 5 is then arranged. This is followed by a further extraction unit 6. The extrusion axis is marked with the position number 8.

FIG. 2 shows the parts of the device that are involved in the separation process. The first extraction unit 4 includes two extraction caterpillars 12, but several caterpillars can also be arranged in one extraction unit, which extract the plastic product 7 from the calibration and cooling tank 3 and convey the separating unit 10 in the extrusion direction Hin. The separating unit 10 consists of a bead 14 on which the separating tools 13 are arranged. During the separating process, one separating tool 13 encompasses the plastic product 7 and carries out the separating process, while the plastic product 7 continues to be conveyed through the separating unit 10 . After the cutting process, the cutting tool 13 is disengaged. If several separating tools 13, here three by way of example, are arranged on the bead 14, another separating tool 13 can carry out the next separating process. Another bead 16 is provided to support the plastic product 7 during the cutting process. The separating process is completed before the separating tool 13, which is arranged on the bead 14, leaves the contact surface between the bead 14 and the plastic product 7 again. This contact length 17 is reproduced purely schematically.

FIG. 3 shows an enlargement of FIG. 2, in which the bead 14 with a separating tool 13 can be seen. The separating tool 13 comprises a separating means 15 rotating around the plastic product 7, which is symbolized by the arrow. The separating tool 13 runs in the extrusion direction 11 at the extrusion speed v. The separating means 15 does not necessarily have to rotate around the plastic product 7; the separating can also be done by simply pressing it into the soft plastic mass or by clamping it with a saw. FIG. 4 shows a section through the separating unit 10 transversely to the extrusion axis 8. Here it is shown by way of example that the plastic product 7 is supported, conveyed and cut to length by means of three caterpillars. Separating tools 13 are arranged on the caterpillar 14 and run at the same speed as the caterpillar 14 . Two further caterpillars 16 are provided both for supporting and for transporting the plastic product 7 . By means of such a design of the device according to the invention, the first extraction device 4, which is arranged after the calibration and cooling tank 3 and before the separating device 5, could be dispensed with.

FIG. 5 corresponds to FIG. 2 with the same reference numerals. FIG. 5 differs only in that a double arrow is shown on bead 16 and bead 14, which is intended to show schematically that bead 16 and bead 14 can be moved toward or away from the center point of the pipe and thus extrusion axis 8 . This makes it possible to adjust the device to different pipe diameters. This is additionally illustrated in FIG.

FIG. 6 corresponds to FIG. 4 and also has the same reference numerals. The beads 14 and 16 were each provided with a double arrow to indicate the possible movement of the beads to the center of the extruded tube. A smaller diameter tube was shown as a knitted dotted line.

By using a further bead 14 with associated further cutting tools 13, it would be possible to carry out the cutting process simultaneously with two cutting tools 13 or more. This would have the advantage that a cutting process is not carried out by one tool, but by several tools, thus enabling the possible cutting lengths of the plastic product to be even shorter with the same or even higher line speed. During the cutting process, the speed of the bead 14 is synchronous with the extrusion speed v. Depending on the required cutting length of the plastic product 7, the bead 14 with the cutting tool or tools 13 can also run faster or slower. For example, it may be necessary for the cutting tool 13 to be brought back to the starting position for cutting very quickly for the next cutting process, and therefore the bead 14 to run much faster than, for example, the bead 16. If the caterpillar 14 with the separating tools 13 is not used for the separation, it can also act as a support. For this purpose, rollers 18 are arranged on the caterpillar 14, as shown schematically in FIG. 2, so that both support and unrestricted transport of the plastic product 7 are ensured. Otherwise the caterpillar 14 could jam at different speeds. In this way, rolling on the plastic product 7 is ensured at all times.

Due to this possibility of different speeds, variable cutting lengths of the product are possible.

The machine control can regulate the speed depending on the cutting length required, as well as the number of cutting tools 13 on the bead 14 and the length of the contact surface 17.

Reference list:

1 extruder

2 extrusion tool

3 calibration and cooling tank

4 first trigger device

5 separator

6 second trigger device

7 plastic product

8 extrusion axis

9 additional trigger device

10 separation unit

11 extrusion direction

12 trigger caterpillar

13 cutting tool

14 caterpillar with 13

15 release agents

16 more caterpillar

17 Length of contact area of a bead

18 roll at 14v extrusion speed

Claims

8 patent claims:

1 . Device for separating plastic products (7), in particular extruded plastic pipes, comprising at least one first extraction device (4) with at least two extraction caterpillars (12), a separating unit (10) which comprises at least one separating device (5) with at least one separating means (15). , by means of which plastic products (7) can be cut to a predetermined length, characterized in that the cutting unit (10) comprises at least one bead (14) with at least one cutting tool (13), wherein at least one tool ( 13). ) are rotatable.

2. Device according to claim 1, characterized in that the tool (13) is designed such that it encloses the plastic product (7) to be cut off in a U-shape during the cutting process.

3. Device according to claim 1 or 2, characterized in that the separating tool (13) can be moved with the caterpillar (14) at its speed.

4. Device according to one of the preceding claims, characterized in that at least one further bead (16) supports the plastic product (7) during the cutting process and fixes it radially for the cutting process.

5. Device according to one of the preceding claims, characterized in that the plurality of cutting tools (13) are arranged on the bead (14).

6. A method for separating plastic products using a device according to claim 1, wherein an extruded plastic product (7) is conveyed through a separating unit (10) in the extrusion direction (11) at extrusion speed (v) during the ongoing extrusion process, characterized in that at least one separating tool (13) is conveyed with the circumferential speed of the bead (14) in the extrusion direction (11), with at least one cutting tool (13) cutting through the plastic product (7) during the ongoing process, with the circumferential speed of the bead (14) changing with the cutting tool (13 ) to the rotational speed of the other caterpillars (16) can be different.

7. The method according to claim 6, characterized in that the separating process takes place in a time frame in which the separating tool (13) arranged on the bead (14) rests against the plastic product (7).

8. The method according to claim 7, characterized in that the time window by the

Length (17) of the contact surface of the bead (14) with the plastic product (7) is defined.

9. The method according to any one of claims 8 or 9, characterized in that the speed of the bead (14) with the cutting tool (13) during the cutting process is synchronous with the extrusion speed (v).