JPH0316759B2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a heater unit having a substantially C-shape for heating a nozzle, cylinder, etc. in a plastic molding machine such as an injection molding machine or an extrusion molding machine, or other devices. The present invention relates to a heater unit that can be used in various fields, and in particular to a heater that is sealed with a metal exterior tube to prevent molten resin from flowing in as much as possible, and a method for manufacturing the same.

[Prior Art] Taking as an example a heater whose entire structure is bent into a substantially C-shape, conventionally, a heating wire insulated with a heat-resistant mica plate is sandwiched between the inner and outer surfaces of the heat-resistant stainless steel plate. A heater has been used in which both ends of a wide inner steel plate are bent onto an outer steel plate to cover the entire body and then bent into a cylindrical shape. However, molten resin tends to flow into the joint between the two steel plates or the lead-out portion of the lead, and adheres to the heating wire, often causing premature wire breakage.

In view of this situation, the applicant has built a heating wire into a magnesia insulator tube made into multiple subdivisions, and built this into an armored tube made by flattening a seamless pipe and sealing one end by welding. (Utility Model Publication No. 55-47268). This heater has the advantage that there is no risk of molten resin flowing in, and that it can be used at higher temperatures and higher capacity than conventional heaters.

[Problems to be Solved by the Invention] By the way, since the above-mentioned heater uses a magnesia insulator tube made into a plurality of sub-divided bodies, there is a particular problem in terms of workability, and also in terms of quality control.
The problem was that it required relatively careful consideration.

Therefore, an object of the present invention is to overcome the drawbacks of the heater while retaining the advantages of the above-mentioned heater, to completely prevent the intrusion of molten resin, etc., to be able to be used at high temperatures and with high capacity, and to The object of the present invention is to provide a heater that is easy to work with and whose quality control is relatively easy, and a method for manufacturing the same.

[Means for Solving the Problems] In order to achieve the above object, in this invention, first, a magnesia insulator tube is made into a flat molded product, and leads are attached to a plurality of heating wire insertion holes provided in the flat insulator tube. It has a configuration in which a heating wire is inserted. The flat insulator tube is dipped in an inorganic heat-resistant binder and then dried.The opening from which the lead is pulled out is sealed with a heat-resistant and moisture-proof sealant, and the cavity is filled with heat-resistant insulating powder. It is wrapped in a heat-resistant thin-walled flat pipe in a sealed state, and the whole is pressed and integrated to obtain a flat pipe exterior heater. To make a substantially C-shaped heater, it is sufficient to bend the heater, and it is also possible to use the heater as it is in a flat plate shape without bending. If the final state is heated to 250 to 300°C, the magnesia insulator will be hardened by the heat-resistant binder, further improving its quality.

The method for manufacturing the flat pipe exterior heater includes the following steps.

A step of molding a flat insulator tube having a plurality of heat generating wire insertion holes with magnesia, a step of immersing the magnesia molded product in an inorganic heat-resistant binder and drying it, and inserting a leaded heat generating wire into the insertion hole of the flat insulator tube. A process of flattening a heat-resistant thin-walled pipe, pressing and welding one end, a process of inserting a flat insulator tube into which a leaded heating wire is inserted, a process of filling the void with heat-resistant insulating powder, The process of sealing the mouth of the pipe from which the lead has been drawn out with a heat-resistant and moisture-proof sealant, the process of pressing and welding the mouth end of the pipe except for the lead-out part, and the process of pressing the entire pipe into one piece.

In the above process, the process of flattening the heat-resistant thin-walled pipe and pressing and welding one end thereof does not need to be incorporated into the subsequent sequential processes, and can be a separate, independent process.

[Function] As described above, in the flat pipe exterior heater and the manufacturing method thereof of the present invention, a flat insulator pipe having a plurality of heating wire insertion holes is molded with magnesia,
The structure and method of immersing it in an inorganic heat-resistant binder, drying it, and then attaching a leaded heating wire make it easier to handle, improve workability, and facilitate quality control. Furthermore, it is possible to prevent the flat insulator tube from turning into powder during press molding. In addition, the mouth part from which the lead is pulled out is sealed with a heat-resistant and moisture-proof sealant, and the entire body is sealed with a heat-resistant thin-walled flat pipe, so it is possible to completely prevent the intrusion of molten resin and the like.

[Example] Hereinafter, a more detailed explanation will be given according to an example shown in the accompanying drawings.

FIG. 1 is a cross-sectional view of a flat pipe exterior heater according to the present invention, where 1 is an insulator tube for holding a heating wire. In this invention, it is a flat insulator tube made of magnesia molded product. A heating wire insertion hole 2 is formed. (See Figure 4). If the hardness of this magnesia molded product is too low, it will easily collapse.
There is a risk that it will turn into powder during bending and processing during press processing in the subsequent process, and if it is too hard, there is a risk of cracking during molding, damaging the heating wire, and causing voltage withstand failure. From these points of view, it is preferable to finish with a shore hardness of about 10 to 20 degrees.

The flat insulator tube 1 made of this magnesia molded product is
After molding, it is immersed in an inorganic heat-resistant binder liquid and dried. This is to prevent pulverization during subsequent press working and bending work.

A lead 3 is inserted into the heating wire insertion hole 2 of the flat insulator tube 1 made of the magnesia molded product prepared as described above.
Insert and install the heating wire 3 with a, and then
Insert the entire body except for part a into the heat-resistant thin-walled flat pipe 4.

This heat-resistant thin-walled flat pipe 4 is a flattened thin-walled seamless pipe made of, for example, heat-resistant stainless steel, and has an end 4a opposite to the opening from which the lead 3a is pulled out (see Fig. 6). ), insert the flat insulator tube 1 into which the leaded heating wire 3 has been inserted from the open mouth.

Reference numeral 5 denotes a heat-resistant insulating powder such as magnesia that is filled in the gap of the heat-resistant thin-walled flat pipe 4, and 6 is a heat-resistant and moisture-proof sealing agent that seals the opening.

After filling the thin-walled flat pipe 4 with insulating powder and sealing it with a sealing agent, the mouth end 4a is also pressed and welded, except for the lead pull-out part, so that the thin-walled flat pipe 4 is completely sealed except for the lead 3a. This welding prevents the intrusion of molten resin and also
When bending into a mold, misalignment of the seam of the mouth side end 4a due to the difference in elongation between the inner and outer surfaces is also prevented.

Once assembled and processed as described above, the whole is pressed to integrate the internal insulating powder, flat magnesia insulator tube, and heating wire. As a finishing step, if the whole is heated and dried at 250-300℃, the magnesia insulator will further harden due to the heat-resistant binder.
In addition to completely eliminating the fear of pulverization, the attachment of the heating wire is stabilized, and thermal conductivity is improved, further improving the quality of the heater.

If the heater is not to be used in its flat appearance, but is to be bent into a substantially C-shaped heater as shown in FIG. 7, this is done before the heating and drying. This approximately C-shaped heater is attached to the object to be heated using a tightening band 7 as shown in FIG.
If a tightening band is used, the intrusion of molten resin will be more completely prevented.

In the above embodiment, the heating wire is a single series circuit, but the heating wire is of course not limited to this, and may be divided into a plurality of circuits in the width direction or length direction of the flat insulator tube. In this case, the lead may have a structure in which it is pulled out from both ends instead of being pulled out from one end.

Furthermore, the lead can be drawn out not only in the length direction but also in the width direction and thickness direction. In this case, both ends may be pressed and completely welded.

Further, although the lead 3a is shown as a wire-shaped lead having a braided cover in the drawing, it can also be of a terminal type.

Furthermore, especially in a flat pipe exterior heater with a flat appearance, it is also possible to use a plurality of flat insulator tubes made of magnesia molded products connected together.

[Effects of the Invention] The flat pipe exterior heater and the manufacturing method thereof according to the present invention are as described above, and are capable of eliminating the drawbacks of the conventional approximately C-shaped heater and completely preventing the inflow of molten resin. Of course, the workability and quality control problems of the improved heater provided by the applicant have been resolved, and the applicant has proposed the best heater and manufacturing method for the flat pipe exterior heater with a flat or approximately C-shaped exterior. It could have been provided.

[Brief explanation of drawings]

FIG. 1 is a cross-sectional view showing one embodiment of the flat pipe exterior heater according to the present invention, FIG. 2 is a side view of the same, FIG. 3 is a front view of the same, and FIG. A perspective view of a flat insulator tube, FIG. 5 is a sectional view showing a state in which a heating wire is attached to a flat insulator tube, and FIG. 6 is a perspective view of a flat insulator tube.
Fig. 7 is a cross-sectional view showing the state inserted into a heat-resistant thin-walled flat pipe, Fig. 7 is a perspective view showing the state bent into a substantially C shape, and Fig. 8 is a front view with the tightening band attached. be. 1...Flat insulator tube, 2...Heating wire insertion hole, 3...
Exothermic wire, 3a...Lead, 4...Heat-resistant thin-walled flat pipe, 5...Heat-resistant insulating powder, 6...Sealing agent.

Claims (1)

[Scope of Claims] 1. A flat pipe exterior heater consisting of the following constituent elements, which are entirely pressed and integrated. A magnesia molded product with multiple heating wire insertion holes, a flat insulator tube immersed in an inorganic heat-resistant binder liquid and dried, a heating wire with a lead inserted into the insertion hole, and a heat-resistant and moisture-proof sealing the opening from which the lead is pulled out. A heat-resistant, thin-walled, flat pipe that is completely sealed except for the lead-out lead. Heat-resistant insulating powder filled into the void inside the pipe. 2. The flat pipe exterior heater according to claim 1, wherein the magnesia molded product has a shore hardness of 10 to 20 degrees. 3. The flat pipe exterior heater according to claim 1 or 2, wherein the heating wire is divided into a plurality of circuits in the width direction or length direction of the flat insulator tube. 4. The flat pipe exterior heater according to claim 1, 2, or 3, wherein the heat-resistant thin-walled flat pipe is crushed and welded at both ends excluding the lead extraction portion. 5. A method for manufacturing a flat pipe exterior heater comprising the following steps. A step of molding a flat insulator tube having a plurality of heat generating wire insertion holes with magnesia, a step of immersing the magnesia molded product in an inorganic heat-resistant binder and drying it, and inserting a leaded heat generating wire into the insertion hole of the flat insulator tube. A step of flattening a heat-resistant thin-walled pipe, pressing and welding one end, a step of inserting a flat insulator tube into which a leaded heating wire is inserted, a step of filling the void with heat-resistant insulating powder, The process of sealing the mouth of the pipe from which the lead has been pulled out with a heat-resistant and moisture-proof sealant, the process of pressing and welding the mouth end of the pipe except for the lead extraction part, and the process of pressing the entire pipe into one piece.