JPH0322871Y2 - - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to an insert heater, also known as a cartridge heater.

Insert heaters are ideal heaters that are inserted into the perforated metal part itself when it is difficult to heat the object from the outside or when local heating is performed in a limited area. Brass tubes are generally used as tubes, and steel tubes and stainless steel tubes are particularly used for high-temperature applications.

This insert heater is used to locally heat the die, platen, mold, and other limited locations.

In the conventional insert heater, as shown in Fig. 4, a tube body having the same outer diameter from one end to the other end is used for the heat generating tube 1, and uniform heat generation is achieved from one end of the tube body to the other end. or
As described in Japanese Patent Application Laid-Open No. 50-77944, an electric heating element is placed inside a heating tube formed into a conical or truncated conical shape, and the distribution density is minimum in the central region of the heating tube, and at both ends of the heating tube. There are insert heaters that uniformly distribute the heating energy along the longitudinal axis of the heating tube by distributing the heating energy so that the distribution density increases as the temperature approaches . The insert heater was inserted so as to be in contact with the inner wall of a hole drilled in a heated object such as a die or plan, but the amount of heat dissipated at both ends of the die, platen 2, etc. into which the above-mentioned insert heater was inserted was limited. Since the amount of heat dissipated is larger than that of the intermediate portion, the surface of the die, platen 2, etc. cannot be heated uniformly from one end to the other, resulting in temperature unevenness.

Furthermore, as described in Japanese Patent Application Laid-Open No. 55-124977, the diameter of the tube end of the sheath containing the heat radiation wire is reduced to increase the resistance value of the heat generating wire at the tube end, thereby reducing the heat generation at the tube end. Even if an increased number of heaters are inserted into the perforated part of the heated object, a gap is formed between the tube end and the inner wall of the perforated part, so the increased heat dissipation at the tube end is absorbed by the heated object. The heat is not efficiently transmitted to the ends of the heated body, resulting in uneven temperature of the heated body.

The present invention aims to provide an insert heater that can overcome the above-mentioned conventional drawbacks.

An embodiment of the present invention will be described below based on FIGS. 1 to 3 of the drawings. 3 is an insert heater, 4 is a heating tube, and 5 and 6 are the outer diameters of both ends of the heating tube 4, which will be described later. The enlarged diameter part enlarged so as to come into contact with the inner wall of the perforation part may be composed of a metal pipe or metal rings 7, 8 fitted to the heat generating tube 4 as shown in the first figure, and may be composed of a metal pipe or metal rings 7, 8 as shown in the second figure. The heating tube 4 may be constructed of thicker portions 9 and 10 with an enlarged wall thickness as shown in FIG. The external dimensions and axial dimensions of the enlarged diameter portions 5 and 6 can be changed arbitrarily, and the enlarged diameter portions 5 and 6 are arranged so that the enlarged diameter portions 5 and 6 extend from the tube wall of the heat generating tube 4 to the stepped portion 11 as shown in the first figure.
It may be formed so that it expands through the tapered surface 12, or it may be formed so that it expands through the tapered surface 12 as shown in the second figure. Note that the inclination angle of the tapered surface 12 can be changed arbitrarily. Lead wires 13 and 14 are connected to heating wires built into the heat generating tube 4.

The insert heater 3 having the above configuration,
When inserted into the perforation 16 of the die or platen 15 as shown in FIG. A gap 17 is formed between the diameter-reduced portion in between and the perforation 16, so when the heating wire is energized through the lead wire 14 and the heat generating tube 4 is heated, the ends of the die or platen 15 are More heat is transmitted than the middle part, and compensates for the amount of heat radiated from both ends of the die or platen 15, which is more than the middle part. Therefore, the surface of the die or platen 15 is heated uniformly from one end to the other.

In the above embodiment, an example in which the enlarged diameter portion is provided at both ends of the heat generating tube is shown, but the present invention is not limited to this, and the enlarged diameter portion is provided at one or more locations at both ends and the middle portion of the heat generating tube. Depending on the object to be heated, an enlarged diameter section may be provided, or an enlarged diameter section may be provided at either end of the heat generating tube, or at one or more locations between either end of the heat generating tube and the intermediate section. The number and position of the enlarged diameter portions can be changed as appropriate.

Since the present invention is constructed as described above, extra heat is transferred to parts of dies, platens, molds, and other objects to be heated that have a large amount of heat dissipated.
It is possible to provide an insert heater that can uniformly heat the entire surface of a heated object and prevent temperature unevenness.

[Brief explanation of drawings]

Fig. 1 is a side view showing an example of the insert heater according to the present invention, Fig. 2 is a side view showing another example of the insert heater, Fig. 3 is a sectional view showing the insert in use, and Fig. 4 is a side view showing an example of the insert heater according to the present invention. 1 is a sectional view showing a conventional insert heater in use. 3...insert heater, 4...heating tube,
5, 6... Expanded diameter part, 7, 8... Metal pipe or metal ring, 9, 10... Thick wall part.

Claims (1)

[Scope of Claim for Utility Model Registration] (1) In a heat generating tube of an insert heater that is inserted into a perforation provided in a heated object, the outer diameter of a portion of the heated object that corresponds to a portion of the heated object that radiates a large amount of heat is set to the perforated portion. A gap is formed between the outer diameter of a portion of the object to be heated other than the portion where a large amount of heat is radiated and the inner wall of the perforated portion. An insert heater with a reduced diameter section that reduces the diameter. (2) An insert heater whose expanded diameter portion consists of a pipe or ring fitted into a heat generating tube. (3) An insert heater in which the enlarged diameter part consists of a thickened part of the heat generating tube.