SU273059A1 - Centrifugal pelletizer for granulating thermoplastics - Google Patents

Description

A centrifugal granulator for granulating thermoplastics is known, which includes a drive cylinder with a perforated side surface along which cutting blades are mounted.

In order to improve the quality of the obtained granules on the inner surface of the drive cylinder, knives are fixedly fixed, mounted at an angle to the slotted distribution nozzles located inside the cylinder for feeding the polymer melt.

Knives can be made in the form of a helical spiral.

FIG. 1 shows the proposed granulator, general view; in fig. 2, section A-A in FIG. one; in fig. 3 section bb in fig. one; in fig. k drive cylinder with screw blades.

In the housing 1 of the centrifugal granulator on rolling bearings (slide) is fixed the driving cylinder 2,

consisting of two parts interconnected by a thread. The cutting device of the granulator includes the upper 3 and lower cylindrical clips rigidly interconnected by two or more sector posts 5. On one of the clips (upper) there are securing blades (straight or oval profile) 6, to which compressed air is supplied through pipes 7 The upper holder rests on the thrust bearing mounted on the granulator cylinder 2, and the lower holder slides. only on its outer cylindrical surface. In cylindrical

The 5 cuttings of the cutting device are rigidly fixed with one or several knives 8. The width of the knife is less than the distance between the granulating holes. Double-slit is inserted into the granulator cylinder

Claims (1)

0 (multislit) attached to the polymerization column is a fixed distribution die 9t through which the melt is fed. Inside the cylinder there are knives 10 of an oval profile or knives in the form of a helical spiral, made in conjunction with a cylinder. Heaters 11 are installed in the upper and lower parts of the granulator cylinder. The annular granule receiver 12 is designed to collect and cool the granules with water flowing down its wall. The granules are removed for drying through the cutting rod 13 at the bottom of the granule receiver. There are holes 14 in the upper part of the cylinder to remove volatile thermoplastic components. The melt 15 from the polymerization column is fed to the granulator along the line B (see Fig. 1) through a fixed two-slotted (multi-gap) distribution die. The melt coming out of the die is cut by oval knives 10, the cutting edges of which are parallel to the axis of the granulator cylinder. When working on the cylinder, an additional pulsating load will be applied. Since this load is small, it can be neglected, and to reduce it the gap of the nozzle 9 must be placed under yi to the axis of the granulator cylinder (see Fig. 3, the dashed contour of the slit nozzle). Each of the knives 10 for a half-turn around a double-slotted spinneret cuts a certain amount of thermoplastic melt. Since the speed of a cylinder of a centrifugal graph-n torus is large, the mass of a thermoplastic cut with a knife from a die at a time is small even at high capacities of centrifugal granulators. The cut-off mass of the thermoplastic immediately acquires the speed of the granulator cylinder and, therefore, falls under the action of centrifugal forces. Cutting the thermoplastic with a knife from a die is not pulled out due to the crushing properties of the thermoplastic melt at high shear rates. Under the action of centrifugal forces on the knife 10, the cut mass moves along the profile of the knife and is placed in a thin layer along the inner circumference of the cylinder in the area between the knives. In this case, due to centrifugal forces, gas inclusions are squeezed out of the thermoplastic into the air region 16. Gas inclusions in the region of .16 create a pressure above atmospheric and are removed through the apertures 1 and the gap between the granulator cylinder and the slit die plate to the atmosphere. Depending on the number of knives 10, the thermoplastic mass that is removed with a knife from a double-slot die at a time may be more or less. Therefore, the number of knives is selected so that in half a knife turn around the double-slotted die, the centrifugal force of the knife is freed from the thermoplastic mass cut from the die and is ready to cut off a new batch. Knives 17 for removal of the melt. With a slit die can be made together with a cylinder in the form of a helical spiral. These knives are designed for more viscous thermoplastics (for example, polyethylene). Located on the inner surface of the granulator cylinder, the thermoplastic melt is squeezed out by centrifugal forces from the holes in the form of bundles, which are cut into granules by a cutting device. Prior to supplying compressed air to the blades 6 through the nozzles 7, the cutting device rotates at the speed of the granulator cylinder by friction forces. By pressing compressed air through the nozzles 7 on the blade, the cutting device reduces (increases) the rotational speed relative to the rotational speed of the granulator cylinder to a certain value depending on the pressure of the compressed air exiting through the nozzles. Thus, due to the somewhat lower (higher) rotation speed of the cutting device with respect to the rotation speed of the granulator cylinder, the granules are cut. Reducing (increasing) the pressure of compressed air through the nozzles 7 on the blade 6, you can easily adjust the size of the obtained granules. Claim 1. Centrifugal granulator for granulating thermoplastics, including a drive cylinder with a perforated side surface along which cutting blades are installed, characterized in that, in order to improve the quality of the granules, knives are fixed on the inner surface of the drive cylinder slotted distribution fillers inside the cylinder for feeding the polymer melt. . Fig.Z l | gavshgaiy