JP3010263U - Granulation extrusion equipment for thermoplastics - Google Patents

Abstract

(57) [Summary] [Purpose] Even if the resin has a high viscosity, good quality and homogeneous pellets can be easily and continuously obtained. [Structure] In the screw 2, the front end surface 103 of the flight 101 and the front end surface of the shaft portion 102 are flush with each other along the inner surface of the front vertical wall portion 104 of the die plate 3 with a small gap, and the front end of the die plate 3 is provided. Tapered portion 10 in which the peripheral wall portion on the side is tapered and the die nozzle 4 is disposed.
5, and the screw 2 is attached to the inner surface of the tapered portion 105.
The taper part 20 of the die along the small gap, and the die nozzle 4
The inner diameter on the outlet side of is larger than that on the inlet side. The screw 2 is rotationally driven, the molten resin is transferred forward, is almost not retained in the tip portion of the die plate 3, is pressure-fed to the die nozzle 4, and is discharged from the die nozzle 4.
The discharged molten resin is cut into pellets by the rotary cutter 6 and cooled and solidified by cooling water.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to a granulation / extrusion device for a thermoplastic resin. More specifically, the present invention relates to a granulation extrusion apparatus for producing resin (plastic) pellets by cutting a molten resin (plastic material) continuously discharged from a plurality of die nozzles of a die plate with a rotating cutter that rotates in cooling water.

[0002]

[Prior art]

 Generally, as a granulation method of a thermoplastic resin granulator (pelletizer), (1) the molten resin extruded from a die at the tip of the extruder is introduced into a cooling water tank and cooled and solidified into a strand or a sheet. After that, a strand cutting method or a sheet cutting method in which horizontal or vertical cutting is performed in one or two steps by a fixed blade and a rotating blade through a take-up roller, (2) Melt extruded from the die plate at the tip of the extruder When cutting the resin with a cutter blade of a rotating cutter close to the die plate during cooling solidification or before cooling solidification, a fog water cut method that sprays mist-like water to the cut portion, (3) A hot cut method such as an underwater method in which molten resin is extruded from the die plate into cooling water and cut in water with a cutter blade is usually used. ing.

Each of the above methods has its own advantages and disadvantages. For example, in the so-called cold cut method such as the strand cut method, the granulating device is not directly connected to the extruder, and it is suitable for cutting and traversing. It is relatively easy, but on the other hand, there is a problem with the stability of cooling during extrusion. Further, the so-called hot cut method such as underwater has a problem in cooling and fluctuation of resin pressure. These granulation methods are used depending on the purpose and the plastic material, and attempts have been made by making the most of the characteristics of these methods. By the way, in the above-mentioned granulation, in a single-screw extruder used as an extruder or a twin-screw extruder rotating in the same or different directions, the die plate is fitted on the extrusion side of the screw, and the tip of the die plate is fitted. A die nozzle for discharging the molten resin is formed in the section. However, in all of the above devices, although the tip of the screw is tapered, the die plate has a constant diameter in the axial direction. A large gap, that is, a large pool in which the molten resin is accumulated, was formed between the tip portions of both the die plate and the die plate.

[0004]

[Problems to be solved by the device]

 Therefore, the molten resin transferred forward by the screw was not directly discharged from the die nozzle, but was discharged from the die nozzle after staying in the large pool. Therefore, even if the resin has a low viscosity or good thermal stability, if the resin has a high viscosity, the material will change and the die nozzle will be easily clogged, and high quality and homogeneous pellets will be obtained. There is a problem that it is difficult to obtain continuously. In order to solve such problems, attempts have been made to reduce the thickness of the die plate and shorten the length of the die nozzle. However, if the die plate is made thinner and lighter in this way, sufficient resin pressure cannot be maintained in the die plate, and the screw that is driven to rotate vibrates the die plate itself. A new problem arises that continuous operation becomes difficult. Further, when the resin has a high viscosity, there is also a problem that so-called sharp cutting is required between the die plate and the cutter blade in order to obtain good quality pellets. It is an object of the present invention to provide a thermoplastic resin granulation / extrusion device that can solve the above problems.

[0005]

[Means for Solving the Problems]

 As shown in Fig. 1, the proposed device is based on a granulation extrusion device used for thermoplastic resin molding materials, but it is possible to use screws, die plates, die nozzles, cutter blades, etc. Has improved. The granulation extruder is of a single-screw type or a twin-screw type. In the case of a twin-screw type, the screw rotation may be in the same direction or in different directions. In addition, the applicant of the present application has filed at the same time for the purpose of making the peripheral wall portion on the tip side of the die plate tapered and the tip portion of the rotary cutter tapered (reference number = OMY628-1). The present invention is the one that is improved by applying this. In other words, the feature of the present invention is that the tip of the screw of the extruder is a tapered portion, and the die plate provided at the tip of the extruder is attached to the melted thermoplastic resin. A plurality of die nozzles for extruding into the granulation chamber are arranged at equal intervals in the circumferential direction, and the resin extruded from the die nozzle is cut into pellets by a rotating cutter that rotates in the vicinity of the tip of the die plate. When pellets are cooled and solidified with cooling water, the tip surface of the flight and the tip surface of the shaft of the screw are flush with each other along the inner surface of the vertical wall of the die plate with a small gap between them. The peripheral wall on the tip side of the is the taper part where the die nozzle is arranged, and the taper part of the screw is placed along the inner surface of this taper part with a small gap. There outlet side of the inner diameter of the nozzle in that a larger than the inlet side. On the outer surface of the taper portion of the die plate, lower the portion adjacent to the outlet of the die nozzle on the rear side in the rotation direction of the rotary cutter so that the outer peripheral portion of the cutter blade in the rotary cutter is in the rotational direction more than the inner peripheral portion. As mentioned earlier, the longitudinal direction of the cutter blade may intersect the radial direction of the rotary cutter, and a scooping surface may be formed on the outer peripheral portion of the tip surface of the cutter blade.

[0006]

[Action]

 The screw is driven to rotate, and the resin inside the extruder is heated by shearing force, frictional force, etc., is melted, is transferred to the front while being melted, and is pumped to the die nozzle with almost no retention in the tip of the die plate. And is discharged from the die nozzle. The discharged molten resin is hot-cut into pellets (chips) by a rotary cutter that rotates at a predetermined speed, and then cooled and solidified by cooling water.

[0007]

Embodiment An embodiment of the present invention will be described below in detail with reference to the drawings. FIG. 1 shows the overall arrangement of an apparatus according to an embodiment of the present invention. 1 is an extruder, 2 is a screw, 3 is a die plate, 4 is a die nozzle, 5 is a granulation chamber, 6 is a rotary cutter, 7 is a cutter blade, and 8 is a rotary shaft. The screw 2 built in the extruder 1 is driven to rotate to melt and knead the thermoplastic resin. As shown in FIG. 2, the tip end thereof is a tapered taper portion 20. There is. The screw 2 has a shaft portion 102 and a flight 101 formed in a spiral shape on the outer periphery of the shaft portion 102. The difference between the outer peripheral surface of the flight 101 and the outer peripheral surface of the shaft portion 102, that is, the flight height (depth) t is determined depending on the properties of the molding material, but is constant over the entire length of the screw 2. . As shown in FIG. 3, the tip surface 103 of the flight 101 and the tip surface of the shaft portion 102 are coplanar. The screw 2 may be a single screw or a twin screw, and may be a single row or a double row.

The die plate 3 constitutes a base portion and has a cylindrical parallel portion 106 having a constant diameter in the axial direction, and a peripheral wall portion on the tip side (extrusion side) and a tapered male side. It is composed of a tapered portion (inclined portion) 105 and a tip vertical wall portion (right angle end portion (vertical end portion)) 104 that is orthogonal to the axis. The angle formed by the male taper portion 105 and the axial direction is preferably 45 to 60 °. The outer peripheral surface of the taper portion 20 of the screw 2 extends along the inner surface of the male side taper portion 105 with a small gap. Further, since the tip surface 103 of the flight 101 is located near the rotation axis (rotation center) of the screw 2 and has a low extrusion capacity, it is arranged along the inner surface of the tip vertical wall portion 104 with a small gap. The small gap does not cause a large gap between the tapered portion 20 of the screw 2 and the tip of the die plate 3, that is, a large pool in which the molten resin accumulates. The gap is set so that it does not come into contact with vibration or the like, and preferably about 1 to 2 mm.

In the male side taper portion 105, a plurality of dynozzles 4 penetrating the male side taper portion perpendicularly to the outer surface thereof are arranged in a star-shaped radial pattern at equal intervals in the circumferential direction. The inner diameter of the die nozzle 4 on the outlet side is larger than that on the inlet side. The shape of the die nozzle 4 is free as shown in the figure, and in the figure, die nozzles having different shapes are illustrated by adding (a) and (b) after the reference numeral 4. For example, in the die nozzle 4 (a), a parallel hole is formed from the entrance to the middle, and a tapered hole whose inner diameter is gradually increased from the middle to the exit. The die nozzle 4 (b) is a tapered hole whose inner diameter gradually increases from the inlet to the outlet. The die nozzles 4 (a) and 4 (b) are properly used depending on the resin used. Further, as shown in FIG. 4, on the outer surface of the male side taper portion 105, with respect to the outlet portion of the die nozzle (illustrated by 4 (a) for example), the rear side in the rotation direction of the rotary cutter 6 is shown. Thus, the adjacent portion is reduced by a clearance m to increase the cutting performance of the die plate 3 having a role of a fixed blade. The escape m is preferably less than half the inner diameter of the outlet of the die nozzle 4 (a). The granulation chamber 5 is surrounded by a granulation chamber housing 9.

The rotating cutter 6 is a heavy-duty material in order to withstand high-speed rotation and to avoid vibration as much as possible, and also to withstand rust due to cooling water, and to maintain a certain degree of rotational inertia. It is a one-piece structure of casting. The rotary cutter 6 is located on the extension axis of the die plate 3 and closely faces the tip of the die plate 3. A tip portion of the rotary cutter 6 is formed into a tapered female side taper portion 60, and is externally fitted to the male side taper portion 105. The cutter blade 7 is made of stellite, and is welded or laid on the inner surface of the female side taper portion 60 at equal intervals in the circumferential direction. The tip surface of the cutter blade 7 is precisely polished so as to face the die nozzle 4 with a precise clearance and rotate so that the resin can be cut. The following configuration is adopted so that the cutter blade 7 can perform good cutting. That is, as shown in FIG. 5, in the cutter blade 7, the longitudinal direction of the cutter blade 7 is set in the radial direction of the rotary cutter 6 so that the outer peripheral portion of the cutter blade 7 precedes the inner peripheral portion in the rotational direction (arrow direction). It crosses with a twist angle θ. θ is preferably set to 3 ° to 6 °. Further, as shown in FIG. 6, a scooping surface 70 having a scooping angle ω is formed on the outer peripheral portion of the tip surface of the cutter blade 7. ω is preferably set to 30 ° to 45 °. The rotary cutter 6 is supported by a rotary shaft 8 which is driven to rotate. The rotary shaft 8 is a cooling water supply pipe for supplying cooling water between the die plate 3 and the rotary cutter 6, is hollow, and is open to the tip vertical wall portion 104 of the die plate 3. It

According to the embodiment configured as described above, the screw 2 is rotationally driven, and the resin inside the extruder 1 generates heat due to shearing force, frictional force, etc., and is transferred forward while being melted. . By the way, in the present invention, the peripheral wall portion on the front end side of the die plate 3 is formed as a tapered male side taper portion 105, and the outer peripheral surface of the taper portion 20 of the screw 2 is provided along the inner surface thereof with a small gap. Since the tip surface 103 of the flight 101 of the screw 2 is made the same as the tip surface of the shaft portion 102 and runs along the inner surface of the tip vertical wall portion 104 of the die plate 3 with a small gap, the taper which is the tip portion of the screw 2 is formed. No large gap, that is, a large pool in which the molten resin is stored, is formed between the portion 20 and the tip of the die plate 3.

Therefore, the molten resin transferred to the front as described above is pumped to the die nozzle 4 from the die nozzle 4 with almost no retention between the taper portion 20 of the screw 2 and the tip portion of the die plate 3. Is ejected. Therefore, the molten resin is discharged from the die nozzle 4 without being altered. In this way, the molten resin is discharged from the die nozzle 4 without being deteriorated, and the inner diameter on the outlet side of the die nozzle 4 is set to be larger than that on the inlet side, so that the die nozzle 4 is unlikely to be clogged. Good quality and homogeneous pellets can be easily obtained continuously. Further, in order to shorten the length of the die nozzle 4, it is not necessary to reduce the thickness of the vertical wall portion 104 at the front end of the die plate 3, so that the die plate 3 can be made a heavy object, and the resin pressure within the die plate 3 is sufficient. The rotation of the screw 2 allows the continuous operation to be performed easily without vibrating the die plate 3 itself.

By the way, as described above, the molten resin discharged from the die nozzle 4 is hot-cut (cut) into pellets (chips) by the cutter blade 7 of the rotary cutter 6 which rotates at a predetermined speed. At this time, on the outer surface of the male-side taper portion 105, a portion adjacent to the outlet portion of the die nozzle 4 on the rear side in the rotation direction of the rotary cutter 6 is lowered by a clearance m, and the outer peripheral portion of the cutter blade 7 is reduced. The longitudinal direction of the cutter blade 7 intersects the radial direction of the rotary cutter at a twist angle θ so as to precede the inner peripheral portion in the rotational direction, and the scooping angle ω is set at the outer peripheral portion of the tip surface of the cutter blade 7. Since the scooping surface 70 is formed to improve the cutting performance between the die plate 3 and the cutter blade 7, the resin can be cut into pellets with good sharpness, and the pellets can be made even better and homogeneous. Further, the cooling water is supplied from the rotating shaft 8 between the die plate 3 and the rotating cutter 6 and continuously between both the tapered portions 105 and 60, that is, the cutting region in a radial manner. The cut pellets are cooled and solidified, and are easily blown (exhausted) to the outside in a radial manner from the cutting region and scattered in the granulation chamber 5.

[0014]

[Effect of device]

 As described in detail above, according to the present invention, it is possible to easily and continuously obtain good quality and homogeneous pellets even when the resin has a high viscosity. According to the second aspect, the pellets can be made even better and more uniform.

[Brief description of drawings]

FIG. 1 is an overall side sectional view showing an embodiment of the present invention.

FIG. 2 is a side sectional view showing details of a screw and a die plate.

3 is a schematic cross-sectional view taken along the line AA of FIG.

FIG. 4 is a sectional view taken along the line BB of FIG.

FIG. 5 is a developed front view of a rotary cutter and the like.

6 is a sectional view taken along the line CC of FIG.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Extruder 2 ... Screw 3 ... Die plate 4 ... Die nozzle 5 ... Granulation chamber 6 ... Rotating cutter 7 ... Cutter blade 8 ... Rotating shaft 20,105・ ・ ・ Tapered portion 70 ・ ・ ・ Scooping surface 101 ・ ・ ・ Flight 102 ・ ・ ・ Shaft 103 ・ ・ ・ Tip surface 104 ・ ・ ・ Tip vertical wall

Claims (2)

[Scope of utility model registration request] 1. A tip portion of a screw 2 of an extruder 1 is a tapered portion 20 and a die plate 3 provided at the tip portion of the extruder 1 is granulated with a molten thermoplastic resin. A plurality of die nozzles 4 to be extruded into the chamber 5 are arranged at equal intervals in the circumferential direction, and the resin extruded from the die nozzle 4 is cut into pellets by a rotary cutter 6 which rotates in proximity to the tip of the die plate 3. When the cut pellets are cooled and solidified with cooling water, the tip surface 103 of the flight 101 in the screw 2
And the tip surface of the shaft portion 102 are flush with each other, the die plate 3
The peripheral wall portion of the die plate 3 on the tip side is formed into a taper portion 105 in which the die nozzle 4 is arranged, and the peripheral wall portion on the tip side of the die plate 3 is formed along the inner surface of the tip vertical wall portion 104 of the taper portion 105. The thermoplastic resin granulation extrusion apparatus, characterized in that the taper portion 20 of the screw 2 is provided along the inner surface with a small gap, and the inner diameter of the outlet side of the die nozzle 4 is made larger than that of the inlet side. 2. On the outer surface of the taper portion 105 of the die plate 3, a portion adjacent to the outlet of the die nozzle 4 on the rear side in the rotation direction of the rotary cutter 6 is lowered by an escape distance m, and the cutter blade 7 in the rotary cutter 6 is lowered. So that the outer circumference of the cutter blade precedes the inner circumference in the rotational direction.
2. The thermoplastic resin according to claim 1, wherein the longitudinal direction of the blade is intersected with the radial direction of the rotary cutter 6 at a twist angle θ, and a scooping surface 70 having a scooping angle ω is formed on the outer peripheral portion of the tip surface of the cutter blade 7. Granulation extrusion equipment.