JP6487736B2 - Cartridge heater - Google Patents

Description

  The present invention relates to a cartridge heater, and more particularly to a cartridge heater capable of setting the temperature distribution in the longitudinal direction more easily and in detail than in the prior art.

  Out of the heaters that house the heating wire through an insulator in the metal tube, the electrodes at both ends of the heating wire are led out from one end of the metal tube for the purpose of being inserted into a mold or hot plate. What has been made is generally called a cartridge heater. Usually, this cartridge heater has a structure in which a heating wire is spirally wound around an outer peripheral surface of a cylindrical insulator (see, for example, Patent Document 1).

  In recent years, in order to improve the heat treatment in a mold or a hot plate, it is required that the temperature distribution in the longitudinal direction of the cartridge heater can be accurately set. For this purpose, a configuration in which a plurality of sets of heating wires having different resistance values (heat generation amounts) are housed in a heater and energized as appropriate so as to satisfy a required temperature distribution is conceivable.

  However, in the structure as described in Patent Document 1, since a plurality of sets of heating wires are wound in a spiral shape, the heating wires and the metal tube are close to each other, or the heating wires are in contact with each other to cause a short circuit. There is a problem that it becomes difficult to set the temperature distribution in detail by adjusting the heat generation amount of the heating wire as well as the fear.

Japanese Patent Laid-Open No. 7-192858

  An object of the present invention is to provide a cartridge heater capable of setting the temperature distribution in the longitudinal direction more easily and in detail than in the prior art.

The cartridge heater of the present invention that achieves the above-mentioned object has a pair of through-holes symmetrical about the axial center formed in a cylindrical insulator and extending in the axial direction. Insert the insulator into the bottomed metal tube from the other end surface side, and fill the gap between the pair of through holes and the heating wire with the insulating powder to embed the heating wire. And a cartridge heater in which a gap between the insulator and the metal tube is filled with insulating powder, the heater comprising a plurality of sets of heating lines, and a pair of through holes in which the heating lines of each set are embedded A plurality of sets are formed at equal intervals along the circumferential direction of the insulator, and the length from the one end surface of the insulator in the through hole is made different between the plurality of sets, and the heat generation of each set The wire straddles the other end surface of the other end surface of the insulator. A step is provided in a portion of the other end face of the insulator where at least one set of the heating wires is turned, and at least one set of the heating wires is turned inside the step. The part which is carrying out is arrange | positioned, It is characterized by the above-mentioned.

  According to the cartridge heater of the present invention, a plurality of sets of heating wires are accommodated in the heater without contacting each other with the metal tube, and the amount of heat generated in each heating unit is adjusted by the length of the heating wires. Therefore, the temperature distribution in the longitudinal direction can be set more easily and in detail than in the prior art.

It is sectional drawing of the longitudinal direction of the cartridge heater which consists of embodiment of this invention. It is sectional drawing of the radial direction in the AA arrow shown in FIG. It is sectional drawing of the radial direction in the BB arrow shown in FIG. It is a perspective view which shows the shape of the other end surface side of an insulating core material. It is a perspective view which shows another example of the shape by the side of the other end surface of an insulating core material. It is sectional drawing of the longitudinal direction in the application example of the cartridge heater which consists of embodiment of this invention. It is sectional drawing of the radial direction in FIG. 6, Comprising: (a) shows XX arrow view, (b) shows YY arrow view, (c) shows ZZ arrow view, respectively.

  Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 shows a cartridge heater according to an embodiment of the present invention. In the following description, the case where two sets of heating wires are provided is taken as an example, but the same applies to the case where there are three or more sets.

  In this cartridge heater, two ends 4A are provided with heating wires 3A and 3B that generate heat when energized in a pair of through holes 2A and 2B that are symmetrical about the two axial centers formed in the cylindrical insulating core material 1 and extend in the axial direction. 4B is arranged so as to lead out from the one end face 5. Then, the insulating core material 1 is inserted into the bottomed outer metal tube 7 from the other end face 8 side, and the gap between the through holes 2A, 2B and the heating wires 3A, 3B is filled with the insulating powder 6 to generate the heating wires 3A, 3B is embedded, and the gap between the insulating core material 1 and the outer metal tube 7 is further filled with the insulating powder 6. The insulating core material 1 and the outer metal tube 7 are integrated by reducing the diameter of the outer metal tube 7 by swaging or pressing.

  In general, a cartridge heater used as a heating source for a mold or a hot plate has a dimensional specification having an outer diameter of about 10 to 20 mm and a length of about 100 to 300 mm.

  As the insulating core material 1, a sintered body of magnesium oxide is used. Nickel / chromium, iron / chromium, or pure nickel is used as the material of the heating wires 3A and 3B, and the heating wires 3A and 3B of the embedded portions 9A and 9B serving as the heating portions are processed into a spiral shape. As the outer metal tube 7, a metal tube made of stainless steel, aluminum, copper, iron, or titanium is selectively used depending on the temperature range and application. Further, magnesium oxide is used as the material of the insulating powder 6.

  As shown in FIG. 2, the pair of through holes 2 </ b> A and 2 </ b> B in which the heating wires 3 </ b> A and 3 </ b> B are embedded are formed at equal intervals along the circumferential direction of the insulating core material 1.

And as shown in FIG.3 and FIG.4, the step part 10A, 10B of mutually different height is formed in the part over which heating wire 3A, 3B is straddled on the other end surface 8 side of the insulating core material 1, respectively. The lengths L _A and L _B from the one end face 5 of the insulating core material 1 in the pair of through holes 2A and 2B are different from each other.

  In this way, the two sets of heating wires 3A and 3B are accommodated in the heater without contacting the outer metal tube 7 and the heating wires 3A and 3B are arranged for the amount of heat generated in each heating unit. Since the adjustment is made according to the length, the temperature distribution in the longitudinal direction can be set more easily and in detail than in the prior art.

The lengths L _A and L _B from the one end surface 5 of the insulating core material 1 in the pair of through holes 2A and 2B are shown in FIG. 4 in order to prevent contact between the heating wires 3A and 3B and the bottom surface of the outer metal tube 7. As shown in FIG. 3, it is desirable to make the length shorter than the total length L of the insulating core material 1.

In addition, as in another example shown in FIG. 5, when the stepped portion 10A / 10B is not provided for one set of the pair of through holes 2A and 2B (in this example, L _B = L), the insulating core It is necessary to prevent contact by interposing a disc-shaped insulator or the like between the other end surface 8 of the material 1 and the bottom surface of the outer metal tube 7.

  In general, in the mold and the hot plate, the temperature decrease due to heat radiation is greater at the outer peripheral portion than at the central portion. Therefore, when the cartridge heater is used by being inserted into a mold or a hot plate, a portion corresponding to the outer peripheral portion (one end surface 5 side of the insulating core material 1 in the cartridge heater) is at the center portion (cartridge heater). The calorific value larger than the other end face 8 side of the insulating core material 1 in FIG.

Therefore, with respect to the lengths L _A and L _B from the one end face 5 of the insulating core material 1 in the pair of through holes 2A and 2B, the ratio of the minimum length to the maximum length in the two sets (example in FIG. 4) Then, it is desirable from a practical viewpoint that L _A / L _B ) be 0.1 or more and 0.5 or less, more preferably 0.15 or more and 0.3 or less.

  Between the heating wires 3A and 3B embedded in the two pairs of through holes 2A and 2B, in addition to the length of the heating wires 3A and 3B described above, the heating wires 3A and 3B are processed into a spiral shape. It is possible to adjust the amount of heat generation in more detail by making at least one selected from the pitch of the portions, the diameters of the heating wires 3A and 3B, and the material of the heating wires 3A and 3B different. Note that the pitch of the portions where the heating lines 3A and 3B are processed into a spiral shape may be either continuous or discontinuous along the longitudinal direction, and the size thereof may be ∞ (linear).

In the cartridge heater, when the lengths L _A and L _B are greatly different between the two pairs of through-holes 2A and 2B, two pieces are used without increasing the height difference between the stepped portions 10A and 10B. It is preferable from the viewpoint of manufacturing processing that the insulating core material 1 is used by being connected in the longitudinal direction.

  For example, as shown in FIGS. 6 and 7, two insulating core materials 1 having the shape shown in FIG. 5 are long and sandwiched with a sintered coupling body 11 in which only two pairs of through-holes 2A and 2B are formed. By connecting in series in the direction and changing the position where the heating wires 3A and 3B cross over, the length between the two heating wires 3A and 3B can be increased simply by forming the step portion 10A having a low height. It is possible to make it different.

  In this case, there is no need to interpose a disc-shaped insulator or the like between the other end surface 8 of the insulating core material 1 and the bottom surface of the outer metal tube 7.

DESCRIPTION OF SYMBOLS 1 Insulating core material 2A, 2B A pair of through-hole 3A, 3B Heat generating wire 4A, 4B Both ends 5 One end surface 6 Insulating powder 7 Outer metal tube 8 Other end surface 9A, 9B Embedded part 10A, 10B Step part 11 Sintered coupling body

Claims (3)

A pair of through-holes symmetrical about the axial center extending in the axial direction formed in the cylindrical insulator is disposed so that both ends are led out from one end face of the insulator, and the insulator is bottomed And inserted into the metal tube from the other end surface side, filling the gap between the pair of through holes and the heating wire with insulating powder to embed the heating wire, and in the gap between the insulator and the metal tube. A cartridge heater filled with insulating powder,
A plurality of the heating wires are provided,
A pair of through-holes in which the heating wires of each set are embedded form a plurality of sets at equal intervals along the circumferential direction of the insulator, and the length from one end surface of the insulator in the through-hole, Making the sets different from each other ,
The heating wire of each set is turned so as to straddle the other end surface at the other end surface of the insulator,
Of the other end surface of the insulator, a step is provided in a portion where at least one set of the heating wires is turned, and at least one set of the heating wires is arranged in the step. A cartridge heater characterized by being made . Of the other end surface of the insulator, the portions where the heating wires of each set are turned are provided with steps having different heights, and the heating wires of each set are provided inside the steps. The cartridge heater according to claim 1, wherein a turned portion is disposed . 3. The cartridge according to claim 1 , wherein a plurality of the insulators are connected in the longitudinal direction so that positions in the longitudinal direction of the cartridge heater of portions where the heating wires of each set are turned are different. heater.

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