JPH07195494A - Barrel cooling structure in extruder of blow molding press - Google Patents

Abstract

PURPOSE:To provide a barrel cooling structure of an extruder which can main tain the barrel at a suitable temperature by removing shearing heat of the barrel. CONSTITUTION:A cylinder 20 wherein a spiral groove 22 is carved on an inner peripheral surface is fixed by fitting closely onto an outer peripheral surface of a barrel 1 which extrudes resin molten by heating with a spiral screw 2, and a heater 23 is fixed by fitting closely onto an outer peripheral surface of the cylinder 20. Then, a cover case 21 having a specific space part from the heater 23 is covered. One end part of the spiral groove 22 is opened inside the cover case 21, and the other end thereof is opened outside the cover case 21. Besides, a piping 26 is connected to the cover case 21, and a blower 28 is connected to the piping 26.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a barrel cooling structure in an extruder of a blow molding machine, and more particularly to a cooling structure for preventing the barrel from overheating due to shear heat of resin.

[0002]

2. Description of the Related Art An extrusion apparatus of a blow molding machine is an apparatus for melting and kneading a resin, extruding it from a molding die into a pipe shape, and supplying it as a parison to a mold.

In this extruder, as shown in FIG. 3, a screw shaft 2 is rotatably inserted by a motor 3 into a cylindrical barrel 1 having one end closed, and a nozzle portion 4 is formed at the other end of the barrel 1. In addition, a hopper 6 for accommodating the resin raw material 5 is provided in the barrel 1. An appropriate number of heaters 7 are attached to the outer peripheral surface of the barrel 1 along the longitudinal direction.

Therefore, when the barrel 1 is heated by the heater 7 and the screw shaft 2 is rotationally driven by the motor 3, the resin raw material 5 in the hopper 6 drops and moves into the barrel 1,
While the resin raw material 5 is melted and kneaded, the resin raw material 5 is extruded from the nozzle portion 4 and sent to a molding die (not shown) for molding into a pipe shape.

At this time, the rotation of the screw shaft 2 generates shear heat, which causes the barrel temperature to overheat more than necessary. Therefore, in order to control the barrel temperature to an appropriate temperature, the barrel 1 may be forcibly cooled with water or air.

In the conventional structure for forcibly cooling the barrel 1 with water or air, as shown in FIG. 4, a circulating water passage 8 is provided in a heater 7 closely fixed to the outer peripheral surface of the barrel 1 (a water cooling system). ). The heater 7 is a cast body, and the heating wire 9 is cast in the inside thereof.

Further, as shown in FIG. 5, a housing 10 for accommodating the heater 7 in close contact with the outer peripheral surface of the barrel 1 was mounted on the barrel 1. Air was blown from the blower 11 into the housing 10 and was discharged from the outlet 12 to cool (air cooling method 1).

Further, as shown in FIGS. 6 and 7, a cylindrical body 14 having axial grooves 13 formed on the inner peripheral surface thereof at predetermined intervals in the circumferential direction is fitted into the barrel 1 to form an outer peripheral surface of the cylindrical body 14. The heater 7 was tightly fixed to. When the blower 16 forcibly blows air into the tube body 15 inserted in the tube body 14, it is discharged to the outside through the axial groove 13 (air cooling method 2).

[0009]

However, since the water cooling system directly cools the heater 7, the cooling effect of the barrel 1 is thin, and the heater capacity is substantially reduced, so that the heating effect of the barrel 1 is also reduced. Become thin.

Further, since the air-cooling method 1 cools only the outer peripheral portion of the heater 7, it has a drawback that the cooling effect of the barrel 1 is small and it is impossible to sufficiently prevent overheating due to shear heat.

Further, although the air cooling system 2 has high cooling efficiency, the barrel heating capacity of the heater 7 is lowered and the running cost is increased.

Therefore, the present invention provides a barrel cooling structure of an extruder capable of removing the shear heat of the barrel and maintaining the barrel at an appropriate temperature.

[0013]

A barrel cooling structure in an extruder for a hollow molding machine according to the present invention has a structure in which a spiral groove is formed on an inner peripheral surface of an outer peripheral surface of a barrel for extruding a molten resin heated by a spiral screw. The installed cylindrical body is closely fitted and fixed to the outer peripheral surface of the barrel, and the heater is closely fitted and fixed to the outer peripheral surface of the cylindrical body, and the heater is covered with a cover case having a predetermined space, One end of the spiral groove is opened in the cover case, the other end is opened to the outside of the cover case, a pipe is connected to the cover case, and a blower is connected to the pipe. And

[0014]

The cooling medium supplied from the blower into the cover case first cools the heater, then enters the spiral groove from one end opening into the cover case to cool the barrel, and then It is emitted to the outside from the other end of the spiral groove that opens to the outside.

[0015]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to the drawings. As shown in FIGS. 1 and 2, a cylindrical body 20 made of an aluminum material is closely fitted and fixed to the outer peripheral surface of the barrel 1, and at a predetermined distance from the cylindrical body 20 in the radial direction, a cylinder is formed. It is fixed to a cover case 21 including a cover body 21a and a partition plate 21b.

The partition plate 21b is fixed in close contact with both ends of the cylindrical body 20. The cylindrical body 20 has one spiral groove 22 formed in the inner peripheral surface in the axial direction, one end of which opens into the cover case 21, and the other end 22b thereof opens outside of the cover case 21. is doing.

A heater 23 is closely fixed to the outer peripheral surface of the cylindrical body 20, and the heater 23 is electrically connected to a control unit 25 having a power source through a wiring 24 penetrating an insulating portion of the cover body 21.

A pipe (duct) 26 is opened and connected to the cover body 21, and a blower (blower) 28 is connected to the pipe 26 via a joint 27. Blower 28
Is electrically connected to the control unit 25.

Further, a thermocouple 29 is inserted in the cross section of the barrel 1, and the thermocouple 29 is electrically connected to the control section 25.

It should be noted that the cylindrical body 20 and the cover body 21 are shaped according to the cylindrical shape of the barrel 1 since the barrel 1 is usually cylindrical, but the shape is not limited to this. A tubular shape that matches the cross-sectional shape is determined.

Further, the cylindrical body 20 and the cover case 21 are formed by dividing the cylindrical body into halves so that the cylindrical body 20 and the cover case 21 can be easily attached and detached at the time of mounting on the barrel 1 or at the time of repair and inspection. Good.

To explain the operation of the above embodiment, the heater 23 is heated by a heating command from the controller 25, and the heat of the heater 23 is transferred to the barrel 1 via the cylindrical body 20. Then, the screw shaft 2 rotates to melt and knead the resin.

When the barrel 1 is overheated by shear heat, the thermocouple 29 detects this and sends a signal to the control unit 25, and the control unit 25 issues a cooling command to drive the blower 28.

Air sent from the blower 28 (cooling medium)
Cools the heater 23 in the cover case 21, enters the spiral groove 22 from one end of the spiral groove 22 opening in the cover case 21, and cools the barrel 1 while moving along the outer peripheral surface of the barrel 1. , Is discharged from the other end of the spiral groove 22 opening to the outside of the cover case 21.

Thus, the cooling medium sent from the blower 28 is first heated by heat exchange with the heater 23, and then the barrel 1 is cooled. Therefore, the barrel 1 is not directly cooled and excessively cooled, and the moderate temperature is maintained so that the barrel 1 is not overheated by the shear heat.

[0026]

According to the present invention described above, the cooling medium is heated by initially cooling the heater without directly cooling the barrel with the cooling medium, and then the heated cooling medium is used. Since the barrel is cooled, the barrel is not cooled excessively and the melting of the resin is not hindered.
It can be maintained at a suitable temperature.

Further, since the cooling medium which has become high temperature by cooling the heater and the barrel is discharged to the outside, it is sufficient that the blowing function and capacity are small, the size and size can be reduced, and the power consumption can be reduced.

[Brief description of drawings]

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

FIG. 2 is a sectional view taken along line AA of FIG.

FIG. 3 is a schematic explanatory view of an extruder.

FIG. 4 is a sectional view showing a conventional barrel cooling structure.

FIG. 5 is a sectional view showing a conventional barrel cooling structure.

FIG. 6 is a sectional view showing a conventional barrel cooling structure.

7 is a sectional view taken along line BB of FIG.

[Explanation of symbols]

 1 ... Barrel 2 ... Screw shaft 20 ... Cylindrical body 21 ... Cover case 21a ... Cover body 21b ... Partition plate 22 ... Spiral groove 23 ... Heater 24 ... Wiring 25 ... Control part 26 ... Piping 27 ... Joint 28 ... Blower 29 ... Thermocouple

Claims (2)

[Claims] 1. A cylindrical body having a spiral groove formed on the inner peripheral surface of the outer peripheral surface of the barrel for extruding the heated and melted resin with a spiral screw is closely fitted and fixed to the outer peripheral surface of the barrel. A heater is fitted and fixed in close contact with the outer peripheral surface of the body, a cover case having a predetermined space is covered from the heater, one end of the spiral groove is opened in the cover case, and the other end is A barrel cooling structure in an extruder of a hollow molding machine, characterized in that it is opened to the outside of a cover case, a pipe is connected to the cover case, and a blower is connected to the pipe. 2. The barrel cooling structure for an extrusion device of a blow molding machine according to claim 1, wherein the cylindrical body and the cover case are formed in a half mold.