JPH01215526A - Heating method for heating cylinder of injection device and device there - Google Patents

Abstract

PURPOSE:To contrive speedup in heating and temperature rise of a molding material, by winding a metallic cylinder of a specific structure capable of electrifying a great current round an injection screw. CONSTITUTION:A metallic cylinder 10 into which an injection screw 16 is inserted is coated with an insulator layer 12. Voltage of 0-200V is applied to the metallic cylinder 10 through a primary winding of a transformer 26 based on a movement of a slide terminal of a slide transformer 28. When resistance between connecting terminals 24a, 24b is R, a secondary current of the transformer 26 is 1 and numbers of turns of the primary winding and secondary winding of the transformer 26 are respectively W1, W2, Joule heat J shown by a formula I is generated on the metallic cylinder 10 according to secondary voltage V0 of the slide transformer 28. The metallic cylinder 10 can be heated arbitrarily and swiftly from a nonheating state within a sufficiently high temperature sphere from a practical point of view.

Description

TECHNICAL FIELD The present invention relates to a novel method and apparatus for heating a heating cylinder of an injection device.

(Prior Art) Heating of a heating cylinder in an injection device is generally performed by applying electricity to a band heater wound around the outer periphery of a metal cylinder constituting the heating cylinder.

(Problem to be solved) However, in the heating method using such a band heater, there is a delay due to heat transfer between the time when the band heater is energized and the molding material in the heating cylinder is heated, and the heating and fluidization (plasticization) of the molding material is caused. When there is a need to rapidly heat or raise the temperature of the molding material during operation or injection operation, there is a problem in that the molding material cannot be heated or raised quickly.

The present invention has been made with these circumstances in mind, and its purpose is to provide a method and device for heating a heating cylinder that can quickly heat and raise the temperature of a molding material. There is a particular thing.

(Solution Means) In order to achieve the above object, the heating tube heating method according to the present invention consists of a metal tube whose inner circumference is electrically insulated from the outer circumference, and a large current is applied to the metal tube. The heating cylinder is characterized in that the heating cylinder is heated by applying electricity to generate Joule heat in the metal cylinder.

Further, the heating device for a heating cylinder according to the present invention is constructed of a metal cylinder that electrically insulates the inner peripheral part of the heating cylinder from the outer peripheral part, and provides an alternating current output capable of outputting a large alternating current to the metal cylinder. By connecting a device and passing a large alternating current output from the alternating current output device through the metal tube, Joule heat is generated in the metal tube and the heating tube can be heated. Features.

(Function/Effect) According to the method of the present invention, the metal tube in contact with the molding material can be directly heated by passing current through the metal tube, so the molding material can be quickly heated and raised in temperature. Therefore, when keeping the temperature of the molding material, it is possible to avoid increasing the temperature of the molding material more than necessary, thereby advantageously suppressing thermal deterioration of the molding material.

Moreover, according to the device of the present invention, it is possible to advantageously conduct a large current to the metal tube, and the method of the present invention can be advantageously realized.

(Example) Hereinafter, in order to clarify the present invention more specifically,
Some embodiments thereof will be described in detail based on the drawings.

First, FIGS. 1 and 2 show an example of a heating cylinder of an injection device that is heated according to the method of the present invention, and as is clear from these figures, the heating cylinder of this embodiment is The inner peripheral part is composed of a cylindrical metal cylinder 10 having a predetermined thickness, and an outer metal cylinder 14 that forms the outer peripheral part of the heating cylinder is attached to the outer peripheral surface of the metal cylinder 10 with an insulator layer 12 interposed therebetween. It has a structure in which the two are fitted together.

Here, the metal tube 10 into which the injection screw 16 is inserted is
It is made of wear-resistant metal material and also has an insulator layer 1.
2 has heat resistance, and here, heat resistance and
Insulating materials such as ceramics with high strength, for example, 0.05~
0. It is formed by thermal spraying or vapor deposition on the outer circumferential surface of the metal cylinder 10 to a thickness of approximately L am.

Further, the outer metal cylinder 14 includes a pair of semi-cylindrical divided bodies 18.
．． 18, and has a structure in which these divided bodies 18 and 18 are integrally assembled into a cylindrical shape by bolts '20.

Note that, as shown in FIG. 2, the insulating layer 12
- is also formed on the end face of the metal tube 10, so that the metal tube 10 and the heating tube heft 22 (see FIG. 1) are electrically insulated.

By the way, as shown in FIG. 2, a pair of connection terminals 24a and 24b extend from both ends of the metal cylinder 10 toward mutually opposite sides in the radial direction, and the divided bodies io, connection terminals 24a from the overlapping portion of is.
, 24b are made to protrude outside the outer metal cylinder 14.

As shown in FIG. 3, a secondary winding of a down-down transformer 26 is connected to these connection terminals 24a and 24b. As shown in FIG. 2, in order to insulate each connection terminal 24a, 24b from the outer metal cylinder 14, heating cylinder head 22, etc., the base end of each connection terminal 24a, 24b is An insulator layer 12 is also formed thereon.

Here, a single-phase 200V commercial power supply 30 is connected to the primary winding of the step-down transformer 26 via the slide transformer 2B, and based on the movement of the slide terminal of the slide transformer 28, approximately 0 to 200V An alternating voltage is applied to the primary winding of the step-down transformer 26. As a result, an alternating current corresponding to the secondary voltage of the slide transformer 28 is applied to the secondary winding of the step-down transformer 26, that is, the metal cylinder 1G of the heating cylinder.

In the heating cylinder having such a structure, the connection terminals 24a, 2
4b is R2, the secondary current of the step-down transformer 26 is ゛, and the number of turns of the primary winding and secondary winding of the step-down transformer 26 is Wl and Wg, respectively, then the secondary voltage of the slide transformer 28 is: Depending on Vo (=O to 200V), Joule heat: J expressed by the following equation (1) is generated in the metal tube 10.

Therefore, for example, as the metal tube 10, the connection terminal 24
The resistance R between a and 24b is 0.008Ω, and the down-down transformer 26 has W and Wg of 30Ω.
If you adopt a type of about
It becomes possible to generate Joule heat in the metal cylinder 10, and it becomes possible to arbitrarily heat the metal cylinder IO in a range from a substantially unheated state to a temperature sufficiently high for practical use. In this way, since the metal cylinder 10 that comes into direct contact with the molding material can be directly heated from an unheated state to a temperature sufficiently high for practical use, it is possible to directly heat the metal cylinder 10 that comes into direct contact with the molding material from an unheated state to a temperature sufficiently high for practical use. The molding material can be quickly heated and raised in temperature as needed, from a heat-retaining state to a high temperature that should be raised.

In addition, since the molding material can be quickly heated and raised to the temperature that should be raised in this way, it is not necessary to raise the temperature of the molding material more than necessary in the heat-retaining state, etc. This can advantageously suppress thermal deterioration.

Furthermore, current flows through the metal tube 10 with a substantially uniform distribution, and Joule heat is generated according to the current distribution, so
There is also an advantage that the heating tube (metal tube 10) and, by extension, the molding material can be heated more uniformly than when a heating means such as a band heater is used.

Note that, as is clear from the above description, here, the commercial power source 30. Slide transformer 28 and step-down transformer 2
6 constitutes an alternating current output device 34 capable of outputting a large alternating current that heats the metal cylinder 10 to a temperature sufficiently high for practical use.

In addition, here, in order to facilitate understanding, specific numerical values are shown and explained as the turns ratio: (w, /w,) of the step-down transformer 26 and the resistance: R of the metal cylinder 10. can be changed as necessary.

Next, another embodiment of the present invention is shown in FIGS. 4, 5, and 6.
Each will be explained based on the figures. In addition, below, the electrical heating method and device for the metal tube 10 will be described in detail, and detailed explanation of the specific structure of the heating tube will be omitted. Then, a cylindrical outer metal tube 14 is connected to each metal tube 10 via an insulator layer 12.
It will be assembled as appropriate with the divided form depending on the situation.

First, in FIG. 4, the metal cylinder 10 is divided into a plurality of zones in the axial direction, and the zones closer to the tip of the heating cylinder are heated to a higher temperature to advantageously increase the thermal history time of the molding material. An example of an electrical heating device that can be shortened is shown.

That is, there, the metal tube 10 is divided into three zones Z, Zt, and Z3 from the front end side of the heating tube.
Five connection terminals 36a correspond to those three zones.
36e to 36e are provided.

Here, the connecting terminals 36a and 36b are provided with a phase difference of 180° in the circumferential direction of the metal cylinder IO at the front end of the zone Z1, and the connecting terminals 36c, 36
e has the same phase as the connection terminal 36b, and
It is provided at the boundary between zone Z1 and zone Z2 and at the rear end of zone Z. Furthermore, the connection terminal 36d is
It is provided at the boundary between zone z2 and zone Z with the same phase as the connection terminal 36a. As shown in the figure, connection terminals 36a and 36c, 36b and 36d
, 36a and 36e, separate alternating current output devices 34 are connected to the metal cylinder 10 through their respective corresponding connection terminals, with the current phases at the connection terminals 36a and 36b being mutually coincident. A current is allowed to flow therethrough.

According to such a device, it is possible to heat the molding material with good responsiveness by directly heating the metal tube 10 with electricity, as in the embodiment described above, and an example of the current flow state is shown in FIG. As schematically shown by the arrow, the current density can be increased in the zone near the front end of the heating tube, and the heating temperature can be increased, which advantageously shortens the thermal history time of the molding material. This has the advantage that thermal deterioration of the molding material can be advantageously suppressed.

In addition, in the device of this embodiment, it is possible to simultaneously control the output current of each alternating current output device 34 based on the temperature detected by one temperature sensor, and also to control the output current of each alternating current output device 34 corresponding to each zone. It is also possible to feedback-control the output currents of the alternating current output devices 34 independently from each other based on the detected temperature of a temperature sensor provided.

In the embodiment shown in FIG. 5, four pairs of connection terminals 38a, 38b, 40a, one pair each, are located at a predetermined distance from each other in the axial direction of the metal cylinder 10.
, 40b, 42a, 42b and 44a, 44b are provided. Here, the connecting terminals that are paired with each other are provided so as to protrude to opposite sides in the diametrical direction of the metal tube 10, and the connecting terminals that are adjacent to each other in the axial direction of the metal tube 10 are
They are provided with a phase difference of 90° from each other in the circumferential direction of the metal cylinder 10. As shown in the figure, the secondary windings of separate down-down transformers 26 are connected to each pair of connection terminals, and the amount of current flows through each corresponding slide transformer 28 through these connection terminals. The controlled alternating current flows through the metal tube 10 with a phase position relationship shifted by 90'' in the same direction in the circumferential direction of the metal tube 10.
It is designed so that it can be energized.

In such an energization heating device, four seams/Z of the metal tube 10 corresponding to respective locations of the pair of connection terminals are provided.
I + Zt + Zx + Za, based on the secondary voltage control of the corresponding slide transformer 28,
The heating can be controlled almost independently of each other, and therefore,
This device has the advantage that the temperature distribution state in the axial direction of the metal tube 10 can be controlled more appropriately depending on the molding conditions, etc. than in the device of the embodiment described above.

Note that each zone Z+, Zz, Z3, and Z4 is usually controlled by secondary voltage control of each corresponding slide transformer 28, as shown in FIG. 5, in order to shorten the thermal history time of the molding material. Based on this, the temperature will be controlled so that the zone on the tip side of the heating cylinder has a high temperature.
As is clear from the above description, here, each corresponding down-down transformer 26 and slide transformer 28 and commercial power supply 30 constitute an alternating current output device.

Further, here, the arrangement phase difference between the connecting terminals adjacent in the axial direction of the metal cylinder 10, the current direction to the connecting terminals, etc. can be changed as necessary.

Further, FIG. 6 shows an example in which the metal tube 10 is electrically heated using a commercial three-phase power source. That is,
As shown in FIG. 6, in this embodiment, a set of three connection terminals 46r, 46s, 46t are arranged at a predetermined distance from each other in the axial direction of the metal tube 10. There are four sets. Each set of connection terminals 46r, 46s,
46t are provided with a phase difference of 120° from each other in the circumferential direction of the metal tube 10, and the corresponding connection terminals 46r, 46s, and 46t of each set are provided in the metal tube 10.
They are provided so that they are in the same phase in the circumferential direction. As shown in the figure, the secondary windings of the three-phase step-down transformers 48 provided correspondingly to each set of connection terminals 46r, 46s, and 46t are connected with the same phase relationship. ing.

Here, a three-phase commercial power supply 52 is connected to the primary side of each three-phase step-down transformer 48 via a triac 50, and based on control of each corresponding triac 50 by a voltage regulator 54, The primary voltage of each three-phase step-down transformer 48, and thus the secondary current, are controlled. In other words, each set of connection terminals 46r, 46s,
The amount of current applied to the metal cylinder 10 through the metal cylinder 46t is independently controlled by the voltage regulator 54, and as in the embodiment shown in FIG. The cylinder 1O is divided into four zones Z+ in the axial direction.

The heating can be controlled almost independently for each of Zz, Zs, and Zs.

In addition, in this embodiment, each corresponding three-phase step-down transformer 48
The triac 50, three-phase commercial power supply 52, and voltage regulator 54 each constitute an alternating current output device. In addition, here, each set of connection terminals 46r, 4
6s and 46t are arranged with the same phase relationship in the circumferential direction of the metal cylinder 10, and the connection terminals 46r of each set.

Although the alternating current is applied to the terminals 46s and 46t with the same phase relationship, the phase relationship between the connection terminals 46r, 46s and 46t in the circumferential direction of the metal tube 10 and the connection terminals 46r, 46s and 46t of each pair are different. connection terminal 46r,
The phase relationship etc. of the alternating current passed through the metal tube 10 through the metal tubes 46s and 46t can be changed as necessary, as in the case of using a single-phase power source.

Although several embodiments of the present invention have been described in detail above, these are literal illustrations, and it goes without saying that the present invention should not be interpreted as being limited to these specific examples.

For example, in the embodiment described above, the amount of current applied to the metal tube 10 was controlled by the slide transformer 28 and the triac 50, but the amount of current applied to the metal tube 10 is controlled using other current amount control means. You may also do so.

Further, in the above embodiment, the insulator layer 12 was formed by welding or vapor depositing on the outer peripheral surface of the metal tube 10, but the insulator layer 12 can also be provided by welding or vapor depositing on the outer metal tube 14 side. Furthermore, the metal tube 10 and the outer metal tube 14
It is also possible to provide it as an independent member.

Furthermore, in the embodiment, single-phase and three-phase commercial power sources 3
Although an application example of the present invention has been shown in the case where the metal tube 10 is heated by electricity using a 0.52 mm, it is also possible to heat the metal tube 10 by electricity by using a power source other than a commercial power source. However, it is also possible to heat the metal cylinder 10 by applying direct current.

In addition, although it is omitted to list specific examples one by one, the present invention may be modified in various ways based on the knowledge of those skilled in the art without departing from the spirit thereof. It goes without saying that this can be implemented.

[Brief explanation of the drawing]

FIG. 1 is a partially cutaway front view showing an example of a heating cylinder heated by the method of the present invention, and FIG. 2 is a perspective view of the heating cylinder shown in FIG. 1 with the head removed. FIG. 3 is a circuit diagram showing an example of a heating circuit for electrically heating the metal tube of the heating tube of FIG. 1. FIG. 4, FIG. 5, and FIG. 6 are diagrams corresponding to FIG. 3 for explaining another embodiment of the present invention, respectively. 10: Metal cylinder 12: Insulator layer 14: Outer metal cylinders 24a, 24b: Connection terminal 26: Step-down transformer 28 Ni-Ride transformer 30: Commercial power supply 34: Alternating current output device 36a, 36
b, 36c, 36d, 36e: Connection terminals 38a, 38b: Connection terminals 40a, 40b: Connection terminals 42a, 42b: Connection terminals 44a, 44b: Connection terminals 46r, 46s, 46t: Connection terminals

Claims (2)

[Claims] (1) The inner periphery of the heating cylinder is made of a metal cylinder that is electrically insulated from the outer periphery, and a large current is passed through the metal cylinder to generate Joule heat in the metal cylinder, thereby heating the cylinder. A heating cylinder heating method for an injection device, characterized in that the cylinder is heated. (2) The inner periphery of the heating cylinder is made of a metal tube that is electrically insulated from the outer periphery, and an alternating current output device capable of outputting a large alternating current is connected to the metal tube, and the alternating current output device is connected to the metal tube. Heating tube heating for an injection device, characterized in that the heating tube can be heated by generating Joule heat in the metal tube by passing a large alternating current output from the device through the metal tube. Device.