JPH0347278Y2 - - Google Patents

Description

[Detailed Description of the Invention] Industrial Application Field The present invention relates to a cartridge heater that is used as a heating source when heating a mold for resin molding.

2. Description of the Related Art In general, cartridge heaters have been widely used as heating sources for production equipment, such as when heating molds for resin molding.

The power supply voltage in such fields is generally 200V in Japan due to equipment running costs, etc. Therefore, cartridge heaters with excellent insulation performance are desired for work safety.

Conventionally, the insulating material filled in cartridge heaters has generally been MgO, but since MgO has high hygroscopicity, the end openings of cartridge heaters are sealed to prevent insulation deterioration. However, at present, there is no such sealing method that is absolutely reliable. Typical current sealing methods include (1) sealing with silicone resin, (2) sealing with inorganic adhesive, and (3) glass sealing.

Problems to be Solved by the Invention However, the typical sealing methods described above have the following problems.
That is, in (1) sealing with silicone resin, the insulation deteriorates over time because the silicone resin itself has moisture permeability. Furthermore, in (2) sealing with an inorganic adhesive, the inorganic material itself absorbs moisture. Furthermore, in the case of glass sealing (3), there was a problem in that the glass was susceptible to mechanical stress, which caused the glass to break and cause insulation deterioration.

Due to such sealing problems, as a safety measure in the event of insulation deterioration, equipment is grounded, and if insulation deterioration occurs during use, an earth leakage breaker detects the insulation deterioration and stops power supply to the equipment. This prevents accidents caused by electric shock. However, the current situation is that users are not fully aware of the fact that the insulation of cartridge heaters is susceptible to deterioration and the dangers that arise when insulation deteriorates. In the worst case scenario, if the breaker is not installed, you may be electrocuted. In addition, when using this cartridge heater, it is generally inserted into a hole in a mold, etc., and in this case, the clearance with the hole in the mold, etc. is very small in order to improve heat conduction. Therefore, when the entire cartridge heater is inserted into a hole in a mold or the like, the ground terminal cannot be directly taken out from the cartridge heater and used.

In view of these problems, it is an object of the present invention to provide a cartridge heater in which a ground circuit is reliably formed when the entire cartridge heater is inserted into a hole in a mold or the like.

Means to solve the problem This invention inserts a heating element into a metal pipe,
In the cartridge heater filled with heat-resistant insulating powder, one end of the ground connection terminal is welded and fixed to the inner surface of the opening of the metal pipe, and the other end of the ground connection terminal is connected to a ground wire via a screw. The screw is bent toward the inner circumference of the metal pipe so that the head of the screw does not protrude from the outer circumference of the metal pipe.

Effects According to the above configuration, since the earth connection terminal is provided directly on the metal pipe, the formation of the earth circuit is reliable and electrically safe, and the earth connection terminal and the earth wire are connected to the earth connection terminal. Since the screws do not protrude from the outer periphery of the metal pipe, even when inserting the entire cartridge heater into a hole in a mold, etc., it is easy to insert the heater without any hindrance. It is something that can be done.

Embodiment An embodiment of the present invention will be described below with reference to FIGS. 1 and 2. In the figure, 1 is a metal pipe with both ends open, 2 is a sealing fitting that seals one end opening of the metal pipe 1, 3 is a pair of heat-resistant metal terminals,
Reference numeral 4 denotes a core formed by molding heat-resistant insulating powder, and this core 4 is provided with insertion holes for the pair of heat-resistant metal terminals 3. 5 is a heating wire wound around the outer periphery of the core 4; 6 is a heating element composed of the core 4, the heating wire 5, and a pair of heat-resistant metal terminals 3; inserted into. Reference numeral 7 denotes a guide core formed by molding and processing heat-resistant insulating powder, and this guide core 7 has one side concave for positioning the heating element 6. 8 is a heat-resistant insulating powder filled in the internal space of the metal pipe 1, and this insulating powder 8
After filling, the diameter of the metal pipe 1 is reduced. Reference numeral 9 denotes an earth connection terminal whose one end is welded to the inner surface of the opening at the other end of the metal pipe 1 by plasma welding. A screw is formed. Reference numeral 10 denotes a ground wire for grounding the metal pipe 1, and a crimp terminal 11 is connected to this ground wire 10.
This crimp terminal 11 is then screwed onto the ground connection terminal 9 with a screw 12.
In this case, the ground connection terminal 9 is placed at the center of the metal pipe 1 so that the screw 12 is within the same diameter as the outside diameter of the metal pipe 1, that is, so that the screw 12 does not protrude beyond the outside diameter of the metal pipe 1. It is bent in the direction. 13 is a mold, and FIG. 1 shows the cartridge heater inserted into the hole 13a of the mold 13. As shown in FIG.

Effects of the invention As described above, according to the invention, since the earth connection terminal is provided on the inner surface of the opening of the metal pipe into which the heating element is inserted, the formation of the earth circuit is reliable, and it is electrically safe as well as The head of the screw that connects the earth connection terminal and the earth wire to this earth connection terminal is located on the inside of the opening of the metal pipe, so when using this cartridge heater by inserting the entire cartridge heater into a hole in a mold, etc. This can also be done easily without any hindrance to the insertion of the heater.

[Brief explanation of drawings]

FIG. 1 is a longitudinal sectional view of a cartridge heater showing an embodiment of the present invention, and FIG. 2 is a side view of the same heater. 1... Metal pipe, 6... Heating element, 9,9'
...Earth connection terminal.

Claims (1)

[Scope of utility model registration request] In a cartridge heater in which a heating element is inserted into a metal pipe and filled with heat-resistant insulating powder, one end of a ground connection terminal is welded and fixed to the inner surface of the opening of the metal pipe, and a ground wire is connected to the metal pipe through a screw. The other end of the ground connection terminal connected to the cartridge heater is bent toward the inner circumference of the metal pipe so that the head of the screw does not protrude from the outer circumference of the metal pipe.