CS195303B2 - Facility for granulation of the molten band of the thermoplastic materials - Google Patents

Abstract

1520571 Cutting filaments AUTOMATIK APPARATE-MASCHINENBAU H HENCH GmbH 28 Jan 1976 [28 Jan 1975] 03266/76 Heading DIF Strands 2 extruded from a row of nozzles 1 are drawn along a delivery channel 5 by rollers 8, 9 and granulated by cutter roller 18, water being supplied to the delivery channel, said channel projecting from the straight line joining the row of nozzles to the nip of rollers 8, 9 at least downstream of the nozzles and upstream of the nip so that the strands are pressed against the base of the channel 5. Water from reservoir 12 flows down the channel to cool the strands and prevent them sticking to it. Further water is applied by sprays 16. The base of the channel may have 6 longitudinal grooves or corrugations to guide and separate the strands. These grooves may be confined to the top and bottom of the channel containing the line 10 at which the strand path bends and the line 11 at which the strands leave the base of the channel. Between these portions the channel may have transverse grooves to reduce the flow of water and induce turbulence. One or more of the rolls 8, 9 may have circumferential grooves to guide the strands and one or more rolls may have longitudinal grooves to facilitate gripping of the strands. The extent to which the delivery channel projects can be varied by moving it horizontally. The angle it makes with the vertical can be varied by rotating it about one pivot 25, 26 and moving the other pivot. The tension applied to the strands is thereby varied. In the embodiment of (Fig. 4, not shown) the channel is convex with respect to the strands. Flap 15 is pivoted about 29. When strand extrusion begins the flap is in the position shown in dashed lines so that the initial length of each strand is diverted along channel 27. When the strand thickness has stabilised the flap is moved to its full line position in which it collects the strands and feeds them to the delivery channel. A further pivoted flap (32, Fig. 4, not shown) may be positioned part way along and close to the delivery channel. When it is pivoted so that its free, upper, end contacts the channel the strands are diverted from the channel and are thus conveniently observable. A mirror image apparatus including a channel and cutting wheel may be provided, Fig. 10, not shown. The second channel and cutter may be moved into position below the row of orifices 1 if the first cutter has to be serviced. Cooling water is supplied tangentially to the cutting wheel 18 via valve 24 and pipe 23 which merges into a collection channel 21. The channel 21 may have an upward bend (38, Fig. 9, not shown). Figure 11 shows how a cutter roller 101 cooperates with a counterblade 104 to cut granules 105 from strands 2. Cooling water flows over the top of housing wall 106. It is divided into a main stream 111 tangential to the cutter roller and a second stream 112 by an adjustably positioned bar 110 or roughly triangular cross section. The granules 105 are thus wetted soon after they are cut and before they contact housing 106 or any other part of the apparatus.

Description

BACKGROUND OF THE INVENTION The present invention relates to an apparatus for forming granules from strips of thermoplastic materials which pass in a liquid state from a nozzle to a cooling water-washed outflow trough, from which they are further guided to a cutting knife roll.

A device is known from the patent literature in which the melting strips are guided from the top of the outlet channel so that they exit from it in a bent state. This channel thus forms the carrier of the liquid strips which are deflected as they pass from top to bottom. A cutting device is then provided at the end of the channel. The passage of the belt through the cutting device must be carefully adjusted to the continuous speed of the belt, since the belts are lifted by the cutting device. This lifting of the strips from the drainage channel results in their more limited contact with the cooling water passing through the channel, thereby greatly reducing the cooling effect. Furthermore, there is also a risk of undulation and sticking together of the liquid strips passing from one another when the device is set incorrectly. The cutting device must therefore be arranged to handle the runoff rates of the bands from the nozzle, which, however, vary considerably due to varying viscosity.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a device in which the problem of maintaining the same velocity at the exit of the bands from the nozzles and the entry of the bands into the cutting device is successfully solved.

This object is achieved by providing, in a device for granulating a liquid strip of thermoplastic material flowing from the nozzles into a drainage trough filled with cooling water, from which the bands are guided to a cutting knife roll in which the drainage trough is arranged an area between the nozzles and the inlet of the feed rollers arranged at the outlet of the outflow trough to ensure a constant tension of the liquid strips along the outflow trough, the bottom of which extends over the junction of the nozzle outlet and the inlet of the feed rollers.

By overlapping the outflow trough across the nozzle outlet and feed roller inlet, the liquid strips are not lifted as they pass through the outflow trough. at a discharge rate from the nozzles; because these differences are compensated by pulling the feed rollers.

The overflow of the drainage trough behind the nozzles and in front of the feed rollers thus keeps the liquid strips in forced contact with the drainage trough, which is occasionally interrupted by a film of the cooler.

5 3 0 3 water, thus eliminating lateral and longitudinal vibrations of the belts. The longitudinal oscillation is thereby eliminated by friction of the strips against the trough. The transverse oscillation cannot occur in the outflow trough at all due to the rollers pulling the rolls. This mechanical stabilization then does not allow the side-by-side strips in the drain channel to stick together. The equipment further saves space.

Furthermore, there is known from the patent literature a device for granulating strips of thermoplastic material with a feeding device consisting of a pair of conveyors through which the outgoing belts are discharged from the nozzles, in which, in the event of a failure, water-deflecting plates are arranged. These sheets are always activated when no liquid strip is fed through the feed device. In this solution, a solid drainage trough cannot be used through which the liquid strips would pass in a stretched state.

In the apparatus according to the invention, the outflow trough may be arranged so that both downstream of the nozzles and upstream of the feed rollers they are inclined against the junction between the outlet of the nozzles and the feed rollers inlet, or can be bulged towards the passing liquid strips. This ensures the required tension on the belts both behind the nozzles and in front of the feed rollers.

It has been shown that the trough may have a flat bottom in cross section, acting on the strips. tension ensures the stability of the strips at the bottom of the trough. However, if, for reasons of space or in order to achieve a particularly large granulation capacity, a very close location of the outflow trough is required, it is expedient to provide its bottom with longitudinal grooves in the area adjacent to the nozzles and feed rollers.

At lower viscosity. It is required to limit the speed of the cooling water in the drain channel. . so that the tape does not have an "excessive" tension. To reduce the speed of the cooling water, the bottom of the drainage trough is at. its central part provided with transverse grooves. These transverse grooves · inhibit the cooling water passing through the drain channel from top to bottom. This creates additional turbulence of the cooling water, which leads to an increase in the temperature difference between the liquid tapes and the cooling water.

The efficiency of the feed rollers can be increased by at least one. the feed roller is provided with longitudinal grooves. If circumferential grooves are formed on one feed roller, preferably longitudinal grooves are also formed on the other feed roller. These longitudinal grooves facilitate the extraction of the tapes, especially during the start-up period of the apparatus, when the tendency is to produce tapes of larger cross-section through the nozzles.

In order to automatically guide the strips into the outflow trough as the device is started, an oblique overflow is formed at the upper end of the outflow trough, which crosses the slope of the liquid strips exiting the nozzles. When the plastic liquid material is then ejected from the nozzles, the liquid material strips first fall on this oblique overflow from which they are transferred to a further area of the outflow trough. This achieves, inter alia, that when the melt flow is interrupted, the newly extruded tapes are always led automatically from the nozzles to the outflow trough. The inclined overflow is, of course, like the entire drainage bed, washed with cooling water.

If not. it is possible to introduce liquid tapes outside the device when the device is started. the non-homogeneous and uneven strip results in a non-uniform granulate, which is then mixed with a quality granulate at the outlet of the apparatus. Therefore, an inclined overflow in the form of a hinged flap is expediently provided, which, in the tilted state, allows the strips to be introduced outside the trough. The tapes are introduced into the free space where they are. deletes in any way.

Flow rate. the cooling water is expediently secured so that the upper end of the drain channel extends permanently into the cooling water tank from which the cooling water flows into the channel through the overflow. This ensures a uniform flow of cooling water with simultaneous washing of the outflow trough. Additional cooling nozzles may be provided above the drain channel.

In order to adapt the flow rate of the cooling water through the outflow trough to any of the conditions of the flowing tapes, the outflow trough is expediently designed such that its tilt angle is adjustable. In addition, it is possible to overlap the outflow trough through the junction of the nozzle outlet and the feed roller inlet in an adjustable manner for possible change of tension on the strip. This setting is particularly important for relatively thick belts with lower viscosities, for which a high current. The cooling water in the drain channel has a sensing effect. . To achieve the aforesaid adjustability of the outflow trough, they are arranged on. its upper and lower. . swivel end. axis for. feed in parallel line.

To direct the liquid strips during their passage through the drain. trough. a flap is provided in front of this trough, which in the normal position ensures the passage of the strips through the trough.

Equipment. According to the invention, two outflow troughs can be provided in the. mirror design. This in turn increases the capacity of the device and at the same time achieves it. that in case of failure of one part of the device, the remaining part of the device can operate. This arrangement is mainly used in chemical. industry when it is not desirable to flow the flowing strips of material from artificial. mass stopped.

The invention will now be described with reference to the drawings, in which: Fig. 1 is a cross-sectional side view of the device according to the invention; Fig. 2 is a front view of the device according to the invention; Fig. 5 shows a second variant of the device according to the invention in section, with a convex outflow trough; Fig. 6 shows a drainage trough with longitudinal and transverse gutters in plan view; Fig. 7 shows a feeder. Fig. 8 shows a feed roller with circumferential longitudinal grooves, Fig. 9 shows a catch outlet channel, and Fig. 10 shows a mirror-image arrangement of two devices.

The device shown in Fig. 1 is provided with nozzles 1, from which the thermoplastic-plastic material jets flow. The plastic melt is fed to the nozzles 1 from any feed member (not shown). ,

The nozzles 1 make from the plastic melt liquid strips 2, shown in broken lines, which are introduced into the outlet. trough 5, which is reinforced with lateral edges - 4.

The outflow trough 5 is shown here in section. This trough. 5 has a profile in. letter shape. U. The outflow trough 5 extends beyond the junction 6 between the nozzle outlet 1 and the inlet 7 of the two feed rollers 8, 9, so that - the fluid belt 2 is guided from the nozzle outlet 1 to the inlet 7 of the feed rollers 8, 9 downstream 5.

Cooling water from the - water - tank - 12, which is provided at its lower end with an inlet throat 13 in which a pressure reducer 14 is arranged, is led downstream of the outflow trough. The upper end of this inclined overflow 15 - functions in the reservoir 12 - as a dam - over which the cooling water flows over the inclined - overflow - 15 and the outflow trough - 5. In this arrangement - the cooling water flows drainage channel - 5. - in the required amount. At this flow, the cooling - water washes - the liquid - belts 2 - and - at the same time - forms between them, and the drain trough. - a film which prevents the virtually liquid material of the strips 2 from adhering to the trough 5. The liquid strips 2 are cooled along the outlet trough 5, so that at their exit from the outlet 11 of the trough 5 they are at least hardened on their surface.

In the space above the outflow trough 5 there are arranged five further nozzles 16, from which additional cooling water jets on liquid strips 2 passing along the outflow trough 5. These nozzles 16 provide additional cooling of the strips 2.

After leaving the outflow trough 5 at its outlet 11, the liquid strips 2 enter between the two feed rollers 8, 9 by which they are pulled to remain tensioned in the region between the outlet of the nozzles 1 and the inlet 7 of the feed rollers 8, 9. Due to the elevation of the bottom of the outflow trough 5 above the line 6 between the nozzle outlet 1 and the inlet 7 of the feed rollers 8, 9, it is necessary to ensure that the liquid strips 2 are constantly guided along the outlet trough 5 so that they are not subjected to any mechanical oscillation. Thereafter, the liquid strips 2 are fed through a counter blade 17 - onto a cutting knife roll 18 which cuts it - in a known manner into a granulate. .

The first feed roller 8 is arranged on a pivot arm 19 which is pivotable about an axis 20. The arm 19 presses the first feed roller 8 with the desired pressure on the second feed roller 9 so that the pressure between the two feed rollers 8 S results certain- friction. At least one of the feed rollers 8, 9 is provided in a known manner with a drive which - causes tension on the liquid strips passing between - the two feed rollers. cylinders - 8, 9.

The cutter barrel 18 is arranged in a catch trough 31 by which the produced granules are transported further by water. To this end, the bottom 21 of the catch trough 31 has a rounded portion 22, - to facilitate the flow of cooling water entering the catch trough 31 in the region of the cutting knife roll 18.

The cooling water flows through its inlet 23 tangentially to the cylinder 18 with the cutting blades, thereby - immediately flushing - the granules formed on this cylinder 18. - By means of the pressure - this additional cooling water supplied - from the inlet 23 can be adjusted cooling the granulate in the collecting trough. 31 to the desired value. Since the cooling of the liquid strips 2 is previously dependent on the cooling water inflow from the tank 12 and the nozzles 16, this inflow can be controlled by adjusting the valves 14 and 30 as well as the pressure of the additional cooling water in the inlet 23 through the valve 24.

The cooling-water flowing through the outflow trough 5 passes between the feed rollers 8, 9, which are lightly pressed against the liquid strips 2. - Water then. - passes - among them - cylinder 18. cutting knives, which during the granular formation process; it washes - just like the counter-blade - 17. -This- has - as a - consequence- - the dampening of noise generated during - cutting-granules. - From above - - inflow water - reduces the noise of the device; when the roller is running - no-cutter blades. ..

As already mentioned, the advantage of the invention is also that it is possible to adjust the elevation between the bottom of the outflow trough 5 and the connection 6 between the outlet of the nozzles of the outflow trough 5 and the connection 6 between the outlet of the nozzles 1 and the inlet 7. feed rollers - 8, 9 for regulating the tension of the liquid strips 2. As the bottom of the outflow trough 5 exceeds the line 6, the friction of the liquid strips 2 in the outflow trough 5 increases, while the water film The increased friction further ensures that the lower viscosity liquid strips 2 do not stretch significantly when passing along the drain channel 5, which could result in a deterioration in the quality of the granulates produced. Depending on the material from which the granulation strips are pulled, whether the cant of the channel 5 above the connector 6 is the same in the region of its inlet 10 and outlet 11, or if one cant is higher and the other cant is lower. For arbitrary adjustment of the outflow trough 5 in the sense of these conditions, the outflow trough 5 is arranged on the rotary axes 25, 26, which axes can be displaced in parallel. In the case of parallel displacement of the two rotary axes 25, 20 at the inlet 10 and the outlet 11 of the outflow trough 5, the same elevation over the line 0 of the nozzle outlet 1 and the inlet 7 of the feed rollers 8, 9 results. - resp. 20 and a simultaneous displacement of the remaining axis results in a different elevation of the outflow trough 5 above the aforementioned connector 6.

During operation of the device, an undesirable effect may occur, namely that the material coming out of the nozzles 1 during the start time of the operation of the device is thickened so that it cannot pass between the feed rollers 8, 9. In this case this material is cut into granules of undesirable dimensions. In order for the liquid strips 2 of the desired thickness to come from the nozzles 1 to the cutting knife roll 18, an inclined overflow 15 is provided at the upper end of the outflow trough 5, which directs the liquid strips 2 of the desired thickness to the outflow trough 5. At the onset of operation of the device, the inclined overflow 15 is in the position shown in dashed lines in the drawing, thereby opening the way for the liquid strips 2 to the outlet 27 where they are captured in any manner. For this purpose, the inclined overflow 15 is provided at its end with a pivot point 28 which simultaneously serves as a dam 29 for the overflow of cooling water.

After stabilizing the thickness of the liquid strips 2, the inclined overflow 15 returns to the operating position in which it introduces the liquid strips 2 into the outflow trough 5. The dashed position of the inclined overflow 15 is also shown in the event of a failure where with cutting knives.

Fig. 2 is a cross-sectional plan view of the device of Fig. 1; It can be seen from this figure that there are a plurality of liquid strips 2 extending side by side along the outflow trough 5. The device - can be of any width and thus can - granulate a large number - of liquid strips 2 simultaneously. FIG. 2 further shows how the liquid strips 2 exiting the nozzles 1 at the inlet 10 of the outflow trough 5 are bent and introduced into the outflow trough 5 under other cooling water nozzles 16 and exit the outflow trough 5 and enter between feed rollers 8, 9, not shown here. The outflow trough 5 is provided with a reinforced edge 4 over its entire length, which ensures cooling water from the tank 12 is led through the outflow trough.

5. The rim 4 passes at its lower end into a cover 3 which overlaps the first feed roller 8, which then continues to the bottom 21 of the catch trough 31.

Fig. 3 shows the device according to the invention in a perspective view. - This picture shows how. the liquid strips are guided through the 2 - drain channel 5 with - the side edges 4 - downwards, to the roller 18 with the cutting blades and as they leave the granules - through the collecting channel 31 of the device. .

FIG. 4 shows a device which is essentially identical to that of FIGS. 1 to 3 but in which the outflow trough 5 has a different shape. The outflow trough 5 is convex in the direction of the liquid strips.

This creates a uniform pressure between the outflow trough 5 and the liquid strips 2, which has a beneficial effect on the increased friction between the fluid belts 2 and the outflow trough 5.

The device of FIG. 4 is further provided with a flap 32 which is rotatably mounted at a point 33 between the shown and dashed position. In the dashed position, the flap 32 extends the fluid strips 2 away from the outlet channel 5 so that the strips 2 do not reach the area of the feed rollers 8, 9. The flap 32 allows the thickness of the fluid strips 2 to be checked, especially when starting the machine.

FIG. 5 shows a drainage trough 5 in cross-section. The outflow trough 5 is provided with two edges 4 between which a bottom with longitudinal troughs 34 is arranged. In these troughs 34, the liquid strips 2 are guided particularly safely. The grooves 34 of this shape can be used both in the straight outflow trough 5 and in the curved outflow trough 5.

As already mentioned, the outflow trough 5 has transverse grooves 35 in its central part. Such an exemplary embodiment is schematically illustrated in FIG. Here, the drainage trough 5 again has two edges - 4 and - at its upper - and lower - end, longitudinal grooves 34 are arranged. The longitudinal grooves 34 extend both through the inlet 10 and through the outlet 11 of the drainage trough 5.

Transverse grooves 35 are then formed in the central part of the outflow trough 5 by means of which the water flowing through the outflow trough 5 acquires intense turbulence. - This turbulence increases cooling on one side and decreases water flow rate on the other, reducing its entrainment effect.

FIG. 7 shows both feed rollers 8, 9 which are provided with peripheral grooves 36 for guiding the liquid strips 2 to the cutting knife roll 18 in order to obtain transverse stability. These peripheral grooves 36 'may be formed on one or both of the feed rollers 8, 9.

8a, 8b show the feed rollers 8, 9 which are provided with longitudinal grooves 37. In this case, FIG. 8a shows the first feed roll 8 in an axial view and 8b in a side view. The longitudinal grooves can then be formed on one or both of the feed rollers 8, 9. These longitudinal grooves have the task, at the beginning of the operation of the apparatus, of well-catching the liquid strips 2 and improving their passage through the feed rollers 8, 9. grooves 37 can also be combined with peripheral grooves 36.

FIG. 9 shows a catch trough 31 having an ascending bottom 38. Such an ascending bottom 38 is sometimes required for spatial reasons. This also creates conditions for the use of the kinetic energy of the additional cooling water entrainment of the formed granulates on the cutting knife roll 18.

Fig. 10 shows two devices according to the invention in a mirror arrangement.

Claims (15)

Apparatus for granulating liquid strips of thermoplastic materials flowing from nozzles into a drainage trough filled with cooling water, from which the strips are further directed to a cutting knife roll, characterized in that the drainage trough (5) is arranged in the conveying direction of the liquid strips (2) in the region between the outlet of the nozzles (1) and the inlet (7) of the feed rollers (8, 9) arranged at the outlet (11) of the outflow trough (5) to ensure a constant tension of the liquid strips (2) along the outflow trough (5) the bottom of which extends over the connection (6) of the nozzle outlet (1) and the inlet (7) of the feed rollers (8, 9). Apparatus according to claim 1, characterized in that the outflow trough (5) is convex towards the liquid strips (2) passing therethrough. Device according to Claims 1 and 2, characterized in that the bottom of the drainage trough (5) is provided with longitudinal grooves (34) for guiding the liquid strips (2). Device according to one of Claims 1 to 3, characterized in that the bottom of the drainage trough (5) has transverse grooves (35) in its central part. Device according to Claims 1 to 4, characterized in that the at least one feed roller (8, 9) is provided with peripheral grooves (36) for guiding the liquid strips (2). Device according to Claims 1 to 5, characterized in that the at least one feed roller (8, 9) is provided with longitudinal grooves (37) in order to receive the liquid strips (2). Device according to one of Claims 1 to 6, characterized in that an inclined overflow is provided at the upper end of the outflow trough (5). 7 sheets It can be seen from this figure that in this arrangement the continuous production of granulates required in continuous operation is ensured. The productivity of this device is also doubled. In the event of a failure on one branch of the apparatus, the other branch of the apparatus is moved below the nozzles 1. In the figure, this relative displacement is represented by a dashed nozzle, although it is clear that the nozzles are static and the apparatus branches are movable. of the invention (15), which crosses the slope of the liquid strips (2) emerging from the nozzles (1). Device according to claim 7, characterized in that the inclined overflow (15) is formed by a tilting flap, in which the liquid strips (2) pass outside the drain trough (5) in the tilted state. Device according to claim 7 or 8, characterized in that the upper end of the inclined overflow (15) extends into the cooling water tank (12) where it forms a dam (29). Device according to one of Claims 1 to 9, characterized in that nozzles (16) with cooling water are arranged above the liquid strips (2) in the region upstream of the drain channel (5). Device according to Claims 1 to 10, characterized in that the inclination angle of the outflow trough (5) is adjustable. Device according to one of Claims 1 to 11, characterized in that the overflow of the outflow trough (5) above the line (6) between the nozzle outlet (1) and the inlet (7) of the feed rollers (8, 9) is adjustable. Device according to Claims 11 and 12, characterized in that the drain channel (5) is provided at its upper and lower ends with rotary axes (25, 26) for parallel displacement. Apparatus according to one of Claims 1 to 13, characterized in that a flap (32) is provided upstream of the drain channel (5) for discharging the liquid strips (2) outside the feed rollers (8, 9). Device according to one of Claims 1 to 14, characterized in that two drain troughs (5) are arranged in the mirror arrangement in the device.