Wire material granulator

Abstract

The utility model relates to a wire material granulator for granulating wire materials such as plastic wire materials into granules, which is provided with a cutting mechanism, and the cutting mechanism is provided with a cutting rotor capable of being rotatably driven and a reverse cutter matched with the cutting rotor, and a cutting gap is formed between the cutting edge of the reverse cutter and the rotor tooth tip of the cutting rotor. According to the cutting mechanism, at least one sensor is arranged on the fixed reverse cutter and used for determining the cutting gap in the operation period of the cutting mechanism.

Description

TECHNICAL FIELD

[0001] The utility model relates to a kind of line material granulator for granulating line material such as plastic line material into granules, it has cutting mechanism, the cutting mechanism has rotatable drive cutting rotor and the reverse cutter matched with the cutting rotor, cutting gap is formed between the cutting edge of reverse cutter and the rotor tooth tip of cutting rotor. BACKGROUND

[0002] This kind of line material granulator (Stranggranulierer) is generally used for granulating plastic line material, which is produced using casting machine and related nozzle plate, and is transported to line material granulator with cooling water according to setting or specific treatment through conveying groove, please refer to, for example, DE 31 45 613 A1, EP 0 079 609 A1 or US 4,528,157B1. By this line material granulator, food or pharmaceutical active material line material such as food (in the form of macaroni) can also be granulated into tablets. By transporting multiple line materials adjacent to each other in parallel to the cutting mechanism, high throughput can be achieved.

[0003] Here, the cutting mechanism (Schneidwerk) includes rotatably driven cutting rotor, which can have rib-like or strip-shaped cutting protrusions or rotor teeth on its circumferential surface, which cooperate with fixed counter-knife (Gegenmesser). Counter-knife can basically consist of knife blade (Messerleiste), which is positioned adjacent to the circumference of cutting rotor, so that the strip-shaped protrusions or rotor teeth of the passing cutting rotor can knock off plastic line material on the counter-knife.

[0004] In order to be able to transport line material (Strängen) to the working area of the cutting mechanism with controlled direction and speed, i.e. to the area between the counter-knife and the cutting rotor with controlled direction and speed, the supply device is arranged upstream of the cutting mechanism and has counter-rotating supply rollers between which the line material is transported to be supplied to the cutting mechanism.

[0005] For example, documents DE 101 06 677 C1, DE 34 26 316 A1, DE 31 45 613 A1 and DE 26 00078 A1 disclose such cutting mechanisms with a pair of upstream supply rollers or supply rollers.

[0006] In order to achieve a high-quality cutting of the plastic strand and to make the cutting process efficient, the cutting gap between the rotor tooth of the cutting rotor and the blade of the counter-knife has to be set very small and very precisely, wherein the cutting gap should also be as uniform as possible in the length of the cutting rotor and the counter-knife. If the cutting gap is too large, the viscoelastic or viscous strand cannot be cleanly sheared and a clean blade cannot be obtained. Furthermore, the load on the cutting mechanism increases significantly since the strand material can be sheared between the rotor tooth tip and the blade of the counter-knife, which can lead to increased bearing loads, vibrations and higher power requirements.

[0007] Conversely, if the cutting gap is set too small, there is a risk of direct mechanical contact between the rotor tooth tip and the counter-knife, for example in the case of a cutting gap that was initially set very small and becomes even smaller due to thermal loads and resulting deformations.

[0008] As mentioned above, since the cutting gap should be small, but not too small, the setting of the cutting gap of the strand pelletizer is very difficult and cannot be done perfectly even with a lot of experience, since it is difficult to estimate the influences on the cutting gap that occur during operation (e.g. thermal expansion processes and different strand materials), in particular during the start-up process of the strand pelletizer.

[0009] The cutting gap on the strand pelletizer is usually measured manually using so-called spionbleche with very fine graduation (e.g. scales in hundredths of a millimeter) while the machine is stationary, so that the cutting gap between the cutting rotor and the counter-knife can be set precisely in the range of 1 / 100 millimeters.

[0010] Nevertheless, due to the dynamic changes during the start-up process, it is difficult to set the cutting gap correctly. Due to the influence of the hot strand and / or the temperature of the corresponding process water used, the cutting gap changes at the start of the machine with corresponding negative effects on the cutting process. Depending on the different processes, e.g. when cold or hot process water is used, the gap can become larger or smaller, wherein the process is dynamic. This change occurs until a steady state is reached, wherein in extreme cases the cutting rotor can come into contact with the counter-knife and cause corresponding damage.

[0011] In order to counteract these dynamic changes, attempts are made to take corresponding cutting gap measurements at short time intervals in order to identify what happens to the cutting gap under given process conditions. However, this measurement is very tedious on the one hand and relatively inaccurate on the other hand, since the machine cools down very quickly after it is switched off or the temperature changes again, which means that the measurements have to be taken very quickly. In fact, as soon as the machine is stopped and the knife disc is opened, the gap changes again. Utility model content

[0012] It is therefore the object of the utility model to create an improved strand pelletizer of the above-mentioned type which avoids the disadvantages of the prior art and further improves the prior art in an advantageous manner. In particular, the setting of the cutting gap should be improved so that dynamic changes caused by, for example, temperature changes can be better coped with.

[0013] It is therefore proposed to measure the cutting gap between the cutting rotor and the counter-knife during operation, i.e. when the cutting rotor is running and / or when strands are being cut, and to use a sensor system suitable for this purpose. According to the utility model, at least one sensor is provided on the stationary counter-knife for determining the cutting gap during operation of the cutting mechanism. By means of this at least one sensor which is operated during cutting, changes in the cutting gap during operation can be detected or monitored, and in particular dynamic changes in the cutting gap during the start-up process can be detected or monitored. By knowing the dynamic behavior of the cutting gap, the gap size can be set to an optimum value, thereby ensuring on the one hand a high-quality cut and on the other hand avoiding the risk of the cutting rotor coming into contact with the counter-knife.

[0014] In an improved example of the utility model, the at least one sensor is positioned immediately next to or against the cutting edge of the counter-knife so as to be able to detect changes in the cutting gap as directly as possible.

[0015] In particular, the at least one sensor can be rigidly attached to the counter-knife so that the sensor follows or experiences the changes in the distance of the counter-knife from the cutting rotor in the same way as the counter-knife.

[0016] In particular, the at least one sensor can be arranged at least partially embedded in the counter-knife, and with respect to the direction of rotation of the cutting rotor, the at least one sensor can be arranged behind or downstream of the cutting edge of the counter-knife and towards the rotor tooth which is passing the counter-knife. Preferably, the at least one sensor can be located directly below the cutting edge of the counter-knife, wherein "below" means that the cutting edge itself protrudes slightly above the sensor towards the cutting rotor, for example in a roof-like manner, and the passing rotor tooth first sweeps over the cutting edge itself and then over the sensor.

[0017] The sensor can be arranged on the counter-knife, for example so that when the cutting rotor position in which the rotor tooth tip of the rotor tooth of the cutting rotor is just at the cutting edge of the counter-knife, the sensor is just aligned with this rotor tooth when the rotor tooth has turned through an angle of rotation of less than 20°, less than 10° or less than 5°.

[0018] Advantageously, the at least one sensor can be designed to detect the passing rotor tooth tip of the cutting rotor, in particular to detect the distance from the rotor tooth tip.

[0019] Advantageously, the at least one sensor is a non-contact distance sensor. In particular, the sensor can be designed in the form of an eddy current sensor.

[0020] Such an eddy current sensor can determine the distance to electrically conductive rotor tooth tips, which can be made of steel or other electrically conductive alloys, for example. Advantageously, in the case of such an eddy current sensor, the material of the non-conductive medium, such as water or coolant, and the thermoplastic strand do not influence the measurement result, for example.

[0021] In order to be able to detect the rotor tooth tips, which usually pass by very quickly, with sufficient accuracy, the at least one sensor can be operated at a relatively high sampling frequency, which in a refinement of the utility model is greater than 2 kHz, greater than 5 kHz, even greater than 10 kHz or even greater than 30 kHz.

[0022] In an advantageous refinement of the utility model, a plurality of sensors are arranged distributed along the cutting gap in order to be able to measure the cutting gap in different sections of the cutting mechanism. In this way, it is also possible to detect the non-uniform dynamic change in the cutting gap over the entire width, for example, since the supply at the center is greater than at the left and right edges of the cutting mechanism, the center can change more than the left and right edges.

[0023] Advantageously, the strand pelletizer is provided with a cutting gap adjustment device for adjusting the gap size of the cutting gap and with a feed device for feeding the cutting rotor closer to or further away from the counter-knife and / or for feeding the counter-knife closer to or further away from the cutting rotor.

[0024] Advantageously, the feed device comprises an adjustment drive and a control device for controlling the adjustment drive to adjust the cutting gap during operation of the cutting mechanism in accordance with signals from the at least one sensor. BRIEF DESCRIPTION OF DRAWINGS

[0025] The utility model will be explained in more detail below with reference to preferred embodiments and the associated drawings.

[0026] Figure 1 A partly cutaway side perspective view of a strand pelletizer according to an advantageous embodiment of the utility model is shown, which illustrates the cutting mechanism of the strand pelletizer, comprising a cutting rotor and a counter-knife, and a supply device upstream of the cutting mechanism, comprising a pair of counter-rotating supply rollers,

[0027] Figure 2 A partly cutaway side perspective view of a strand pelletizer according to an advantageous embodiment of the utility model is shown, which illustrates the cutting mechanism of the strand pelletizer, comprising a cutting rotor and a counter-knife, and a supply device upstream of the cutting mechanism, comprising a pair of counter-rotating supply rollers,

[0028] Figure 3 A partial enlarged sectional view of an embedded sensor in the counter-knife in Figure 2 is shown, which illustrates the position of the sensor in the counter-knife and relative to the rotor tooth tip of the cutting rotor. DETAILED DESCRIPTION

[0029] As shown, the strand granulator 1 comprises a cutting mechanism 2 having a rotatably driven cutting rotor 3 which is assigned a counter-knife 4 so that strands, for example of thermoplastic, can be severed or sheared off on the counter-knife 4 by the cutting rotor 3.

[0030] In a manner known per se, the cutting rotor 3 has circumferential cutting protrusions or rotor teeth 5 which can be designed as strips and which can extend substantially over the entire length of the cutting rotor 3. Here, the cutting protrusions or rotor teeth 5 can be arranged substantially parallel to the longitudinal roller axis of the cutting rotor 3, but can also extend at an angle thereto or slightly helically along the cylindrical envelope surface of the cutting rotor 3. See Figure 2 and 3 When viewed in cross-section, the rotor teeth can taper as a whole and / or be arranged obliquely with respect to the radial direction so that the tooth tip is slightly inclined forward with respect to the direction of rotation 7 of the cutting rotor 3 in order to “bite” into the strand.

[0031] The counter-knife is arranged on the envelope surface of the cutting rotor 3 and can be designed as a strip or as a stegförmige blade, past which the rotor teeth 5 of the cutting rotor 3 pass. In particular, the counter-knife 4 can have a cutting edge 8 which extends along the envelope surface of the cutting rotor 3, in particular in a manner parallel to the axis of rotation of the cutting rotor 3, and see Figure 2 which can be progressively sharpened or “sharpened” at a slightly acute edge angle.

[0032] Between the cutting edge 8 of the counter-knife 4 and the tooth tip 6 of the rotor tooth 5 of the cutting rotor 3, a cutting gap is defined, the gap size of which can be in the range of a few millimeters.

[0033] In order to deliver the strands to be cut, for example of thermoplastic or food bars, to the cutting mechanism 2 at a controlled speed and direction, a supply device 10 is provided upstream of the cutting mechanism 2, which supply device 10 comprises two counter-rotating supply rollers 11, 12 so that the bars are fed between them and delivered to the cutting mechanism 2. As Figure 2 shown, the counter-knife 4 is located in the transport area of the supply rollers 11, 12 and is arranged between the supply rollers 11, 12 and the cutting rotor 3.

[0034] As is known, see Figure 1 The strand to be granulated, which can come from a continuous casting machine, can reach the supply device by means of a conveying device such as a conveying trough 9.

[0035] As is known, see Figure 2 and 3 In order to be able to determine the gap size of the cutting gap between the blade 8 of the counter-knife 4 and the tooth tip 6 of the cutting rotor 3 even during operation of the cutting mechanism 2, the cutting mechanism 2 is assigned a sensor system having at least one sensor 13, which is arranged on the stationary counter-knife 4. Advantageously, a plurality of sensors 13 can be arranged distributed along the length of the cutting gap in order to be able to determine the gap size in different sections of the cutting mechanism 2.

[0036] As is shown in Figure 2 and 3 , the sensor 13 is advantageously mounted on the counter-knife 4 directly adjacent to the blade 8, such that the sensor 13 follows the change in the distance of the counter-knife 4 from the cutting rotor 3. In particular, the at least one sensor 13 is positioned on a portion of the counter-knife 4 which, with respect to the direction of rotation 7 of the cutting rotor 3, is directly behind or downstream of the blade 8, which portion is reached by the individual rotor teeth 5 after passing the blade 8.

[0037] As is shown in Figure 2 and 3 , the sensor 13 can advantageously be arranged at least partially embedded in the counter-knife 4, wherein the counter-knife 4 can have a bore, for example in the form of a blind hole, which opens towards the cutting rotor 3, into which bore the sensor can be arranged to be embedded. If the sensor is equipped with a data line, a through hole or a lateral hole can also be provided on the counter-knife to lead the data line out. However, the sensor can also have a wireless data transmission module, for example a Bluetooth or radio interface.

[0038] The sensor head of the sensor 13 can be directed towards the passing rotor tooth 5, wherein, as is shown in Figure 2 and 3 , the sensor head can be arranged to be exposed to or flush with the side of the counter-knife which faces the cutting rotor 3.

[0039] The sensor 13 is advantageously designed as a non-contact distance sensor, in particular in the form of an eddy current sensor, which can detect the distance of the sensor head from the tooth tip 6 of the passing rotor tooth 5 and thus the distance of the counter-knife 4 from the tooth tip 6 of the passing rotor tooth 5. The sensor head of the sensor 13 generates an eddy current field directed towards the rotor tooth 5, which is influenced by the ferromagnetic rotor tooth depending on the distance of the ferromagnetic rotor tooth from the sensor head, such that the sensor 13 can provide a sensor signal for characterizing the distance.

[0040] Advantageously, the sensor 13 is operated with a sufficiently high sampling frequency, for example a sampling frequency of more than 5 kHz or more than 100 kHz, in order to be able to precisely detect the very fast passing tooth tip 6.

[0041] Advantageously, the gap size of the cutting gap measured in line can be used to appropriately set the gap size by adjusting the position of the cutting rotor 3 and / or the counter knife 4, which can advantageously also be carried out during operation of the cutting mechanism, but also in a stopped state, wherein the feed device (Zustellvorrichtung) with an adjustment drive can be controlled by the control device in accordance with the signals from the sensor 13 in order to move the cutting rotor 3 closer to or further away from the counter knife 4, wherein the counter knife 4 can also be moved accordingly, if necessary.

Claims

1. A strand pelletizer for pelletizing a strand into pellets, the strand pelletizer having a cutting mechanism (2) comprising a rotatably driven cutting rotor (3) and a counter-knife (4) cooperating with the cutting rotor, wherein, A cutting gap is formed between the blade (8) of the counter-knife (4) and the rotor tooth tip (6) of the cutting rotor (3), characterized in that at least one sensor (13) is provided on the stationary counter-knife (4) for determining the gap size of the cutting gap during operation of the cutting mechanism (2).

2. The strand pelletizer of claim 1 wherein, The at least one sensor (13) is designed as a non-contact distance sensor.

3. The strand pelletizer of claim 1 or 2, wherein, The at least one sensor (13) is designed as an eddy current sensor.

4. The strand pelletizer of claim 1 or 2, wherein, The at least one sensor (13) is arranged on the counter-knife (4) directly adjacent to the blade (8) of the counter-knife (4).

5. The strand pelletizer of claim 1 or 2 wherein, The at least one sensor (13) is directed at the passing rotor tooth tip (6) of the cutting rotor (3) and / or detects the distance of the passing rotor tooth tip (6) from the sensor head of the sensor (13) and / or the counter-knife (4).

6. The strand pelletizer of claim 1 or 2 wherein, The at least one sensor (13) is arranged at least partially embedded in the counter-knife (4) and behind the blade (8) of the counter-knife (4) with respect to the direction of rotation (7) of the cutting rotor (3) and towards the cutting rotor (3).

7. The strand pelletizer of claim 1 or 2 wherein, The at least one sensor (13) is arranged on a side portion of the counter-knife (4) which is reached by a rotor tooth (5) at a rotational angle of less than 20°, less than 10° or less than 5° with respect to a cutting rotor position in which the rotor tooth tip (6) of the rotor tooth (5) is exactly at the blade (8) of the counter-knife (4).

8. The strand pelletizer of claim 1 or 2 wherein, The at least one sensor (13) has a sampling frequency of more than 2 kHz, more than 5 kHz, more than 10 kHz or more than 30 kHz.

9. The strand pelletizer of claim 1 or 2 wherein, A plurality of the sensors (13) are arranged distributed along the length of the cutting gap and mounted on the counter-knife (4).

10. The strand pelletizer of claim 1 or 2 wherein, A cutting gap adjustment device for adjusting the gap size of the cutting gap and a feed device for feeding the cutting rotor (3) closer to or further away from the counter-knife (4) and / or for feeding the counter-knife (4) closer to or further away from the cutting rotor (3) are provided.

11. The strand pelletizer of claim 10 wherein, The feed device comprises an adjustment drive and a control device for controlling the adjustment drive to adjust the cutting gap during operation of the cutting mechanism (2) in accordance with signals from the at least one sensor (13).

12. The strand pelletizer of claim 1 or 2 wherein, The strand is a plastic strand.

Images