JPH0514833Y2 - - Google Patents

Description

[Detailed description of the invention] [Field of industrial application] This invention relates to a heater device used in a material melting cylinder of an extruder for extruding plastic materials, etc., and in particular a sheathed wire with a temperature controllable water-cooled pipe. Concerning improvements to cast-in heaters.

[Conventional technology]

Generally, in an extruder, a plastic material, etc. is charged into a heating cylinder with a screw inserted through it, and as it is transferred forward by the screw, it is heated from outside the cylinder and internal heat generated by the shearing action of the screw is generated. This process melts the material. In this case, in order to maintain a uniform temperature distribution of the molten material within the heating cylinder and perform proper extrusion processing, it is necessary to cool the heating cylinder from the outer periphery and perform precise temperature control. Therefore, the amount of heat generated by the heating cylinder needs to be forcibly cooled with gas or liquid (particularly water).

From this point of view, conventionally, in this type of extruder, a sheathed wire casting heater with a water-cooled pipe configured as shown in FIGS. 4 and 5 has been employed as a heating device for a heating cylinder. That is, in this heater 10, an electric heating sheathed wire 20 and a water cooling pipe 30 are arranged as shown in the figure, and these are used as heater side plates 12 and 14 each having a symmetrical two-part structure so as to surround the outer periphery of a heating cylinder 40. It is cast and molded from the required metal material. In this case, aluminum is usually used as the metal material for casting, but if the operating temperature exceeds 350°C, brass or iron is used. The heater side plates 12 and 14 configured in this manner are respectively clamped from both sides to a required outer circumferential portion of the heating cylinder 40, and are coupled and fixed with appropriate tightening bolts 16.
A temperature sensor 18 such as a thermocouple is provided in the center of one heater side plate 12 so as to reach the inner wall of the heating cylinder 40 . However, each connection terminal 22, 24 of the sheathed wire 20 provided on the heater side plates 12, 14 is connected to a power source that can be controlled as appropriate, and also connects to a water supply system that can also control the water supply port 32 and drain port 34 of the water cooling pipe 30. and connect to the drainage system.

When controlling the temperature of the heating cylinder using a heater configured in this way, the time ratio method has been adopted. This method is a method in which the amount of cooling water is controlled by the ON/OFF time of a solenoid valve according to a certain specified cooling control cycle. For example, use a sheathed wire aluminum cast-in heater with a water-cooled pipe and increase the heater temperature to 150°C.
℃ and the cooling control cycle is 30 seconds, the relationship between the ON time of the solenoid valve (the amount of cooling water per cycle) and the static cooling capacity is shown in Figure 6. According to the static cooling characteristics shown in Figure 6, at a heating cylinder temperature of 100°C to 300°C at which an extruder is generally operated, almost all of the water in the water cooling pipe evaporates when the amount of cooling water is small. The amount of heat absorbed increases as the amount of cooling water increases. However, when the amount of cooling water increases, new cooling water passes through before the temperature of the inner wall of the water cooling pipe has fully recovered, resulting in a decrease in the temperature difference between the water temperature and the inner wall of the water cooling pipe, and the amount of heat given to the cooling water by the heater decreases. The rate of vaporization decreases, and the cooling effect gradually decreases.

Furthermore, in the static cooling characteristics shown in Figure 6, almost all of the cooling water is vaporized in the region (0 to 1.25 seconds), and the region (1.25 to 12.5 seconds) is a transition region from vaporization to non-vaporization. , almost no cooling water evaporates in the region (after 12.5 seconds). In other words, with the amount of cooling water in the area, most of the cooling water vaporizes near the water-cooled pipe entrance, so the cooling effect of the water-cooled pipe is concentrated near the inlet. Covers the entire area. However, FIG. 7 is a characteristic diagram showing the temperature difference between the left and right ends of the heater side plate based on the static cooling characteristics shown in FIG. 6 described above. From the characteristic diagram shown in FIG. 7, it can be seen that the temperature difference is almost the same in each region.

[Problem that the invention attempts to solve]

According to the conventional cast-in sheathed wire heater with a water-cooled pipe described above, the cooling water has a single channel structure that runs from one water supply port to the other drain port, so it depends on the amount of cooling water. Since the cooling effect is not constant over the entire length of the water cooling pipe,
For example, the response characteristics of a temperature sensor provided in the center of the heater side plate become unstable, and therefore the temperature control characteristics become unstable. Particularly, when the amount of cooling water is small, the cooling effect is concentrated near the inlet of the water cooling pipe, which has the disadvantage of adversely affecting thermal effects on the zone adjacent to the heater device of the heating cylinder.

Therefore, the purpose of the present invention is to provide a sheathed wire casting heater with a water-cooled pipe installed in a heating cylinder for melting plastic materials, etc. in an extruder.
To provide a heater device for an extruder that can improve temperature control performance by improving the flow path configuration of the water cooling pipe so that cooling efficiency can be stably maintained against fluctuations in the amount of cooling water flowing into the water cooling pipe. be.

[Means for solving problems]

The heater device for an extruder according to the present invention is equipped with a water-cooled pipe and a sheathed wire for electric heating, and these are integrally cast and molded with a required metal material to form a heat side plate, and this heat side plate is used to heat the extruder. In a heater device for an extruder that is arranged around the outer periphery of a cylinder and fixedly connected to the cylinder, a water inlet for supplying cooling water is provided in the center of the heater side plate, and water cooling is provided inside the heater side plate so that the water is distributed to both sides. A feature is that pipes are arranged and drainage ports are provided at both ends of these water-cooled pipes.

In the extruder heater device described above, the water cooling pipe is constructed by leading out a branch pipe branching from the middle part of one system of water cooling pipes from inside the heater side plate at the center thereof, and providing a water supply port in this branch pipe. be able to.

Moreover, the water cooling pipe can also be configured as two systems of water cooling pipes each led out from the center of the heater side plate.

[Effect]

According to the heater device for an extruder according to the present invention, cooling efficiency can be improved even when the amount of cooling water is small by supplying cooling water to the water cooling pipes branched into two directions from the center of the heater side plate. Not only is this possible, but the temperature sensor also responds appropriately, making it possible to stabilize the temperature control characteristics.

〔Example〕

Next, embodiments of the heater device for an extruder according to the present invention will be described in detail below with reference to the accompanying drawings.

FIG. 1 and FIG. 2 are a side view and a sectional view showing an embodiment of a heater device for an extruder according to the present invention. In addition, in FIGS. 1 and 2, for convenience of explanation, the same reference numerals are used for the same components as those of the conventional heater shown in FIGS. 4 and 5. The heater 10 of this embodiment has a basic configuration similar to that of a conventional heater, and includes an electric heating sheathed wire 20 and a water cooling pipe 30, and these are cast and formed from a metal material such as aluminum, and the heater side plate 12, 14 respectively. However, in this embodiment, one system of water cooling pipes 3
0, a branch pipe 35 is provided in the middle of the heater 10, and the branch pipe 35 is led out to the outside of the heater 10, and a water supply port 36 is provided. Therefore, the heater 1 of this embodiment
0, both end openings 32 of the water cooling pipe 30,
34 are respectively drain ports, and two systems of water cooling pipes are constructed. Note that the heater side plates 12 and 14 configured in this way are connected to the heating cylinder 4 as in the conventional case.
0 from both sides, and are connected and fixed with appropriate tightening bolts 16. Further, a temperature sensor 18 is provided at the center of one heater side plate 12.

The heater of this embodiment configured as described above is connected to the water supply system through the common electromagnetic valve 42 for each of the water supply ports 36 of the branch pipe 35. Further, openings 32 and 34 at both ends of the water cooling pipe 30 are connected to a drainage system. By controlling the opening time of the electromagnetic valve 42 in each predetermined cooling control cycle, appropriate temperature control can be achieved.
That is, by configuring the water supply system of the water-cooled pipe 30 as in this embodiment, the cooling water supplied from the branch pipe 35 is branched at the water-cooled pipe 30 and drained, thereby improving the cooling efficiency of the water-cooled pipe. can do.

FIG. 3 shows another embodiment of the heater device according to the present invention. That is, in this embodiment, the intermediate portion of the water cooling pipe 30 is separated, and the separated ends 36 and 38 are led out of the heater side plates 12 and 14 to form a water supply port.
The rest of the structure is the same as the embodiment shown in FIG. However, in the heater 10 of this embodiment, the water supply ports 36 and 38 are connected to the water supply system via a common solenoid valve 42. Further, openings 32 and 34 at both ends of the water cooling pipe 30 are connected to a drainage system.

In the heater of this embodiment configured in this manner, as in the previous embodiment, appropriate temperature control can be achieved by controlling the opening time of the solenoid valve 42 in each predetermined cooling control cycle. . In addition, in the heater of this embodiment, the cooling water supplied to the two water cooling pipes 30 from independent water supply ports 36 and 38 via the solenoid valve 42 is branched and introduced, so the amount of cooling water is particularly reduced. It is possible to effectively disperse the cooling effect, which concentrates near the inlet of the water-cooled pipe when the amount of water is low.

[Effect of idea]

As is clear from the embodiments described above, according to the present invention, for the water cooling pipe of the sheathed wire cast-in heater with a water cooling pipe, a branch pipe for connecting to the water supply system is led out from the middle part or is directly branched. By deriving this, it is possible to easily configure the water-cooled pipe, which used to be one system, into two systems, effectively achieving the cooling effect in all water-cooled pipes, especially when the amount of cooling water is small, and improving the operating conditions of the extruder. It is possible to properly and stably adjust the temperature of the molten material in the heating cylinder that is compatible with the above.

Although the preferred embodiments of the present invention have been described above, the present invention is not limited to the above-described embodiments, and it goes without saying that various improvements and changes can be made without departing from the spirit of the present invention. It is.

[Brief explanation of the drawing]

FIG. 1 is a side view showing an embodiment of a heater device for an extruder according to the present invention, FIG. 2 is a cross-sectional view taken along the line -2 of the heater device shown in FIG. 1, and FIG. 3 is a side view showing an embodiment of a heater device for an extruder according to the present invention. A side view showing another embodiment of the heater device,
Fig. 4 is a side view of a conventional heater device for an extruder, Fig. 5 is a sectional view taken along the - line of the heater device shown in Fig. 3, and Fig. 6 is a static cooling characteristic diagram of the heater device shown in Fig. 4. , FIG. 7 is a characteristic diagram showing the temperature difference between the left and right ends of the heater device having the static cooling characteristics shown in FIG. 6. 10... Heater, 12, 14... Heater side plate,
16...Tightening bolt, 18...Temperature sensor, 20
...Electric heating sheathed wire, 22, 24...Connection terminal,
30... Water cooling pipe, 32, 34... Opening, 35
... Branch pipe, 36, 38 ... Water supply port, 40 ...
...Heating cylinder, 42... Solenoid valve.

Claims (1)

[Scope of Claim for Utility Model Registration] (1) A water cooling pipe and a sheathed electric heating wire are provided, and these are integrally cast and molded with a required metal material to form a heat side plate, and this heat side plate is heated by an extruder. In a heater device for an extruder that is arranged around the outer periphery of a cylinder and connected and fixed, a water supply port for supplying cooling water is provided in the center of the heater side plate, and the water is divided to both sides inside the heater side plate. A heater device for an extruder, characterized in that water cooling pipes are arranged and drainage ports are provided at both ends of these water cooling pipes. (2) In the heater device for an extruder according to claim 1 of the utility model registration claim, the water cooling pipe has a branch pipe that branches from the middle part of one system of water cooling pipes from inside the heater side plate. , a heater device for an extruder that has a water supply port provided in this branch pipe. (3) A heater device for an extruder according to claim 1, wherein the water-cooling pipe is composed of two systems of water-cooling pipes each led out from the center of the side plate of the heater.