Heater wire

Abstract

The objective is to provide a heater wire that can stably form voids inside the heater wire to improve workability when removing the coating layer, and is also suitable for reducing the diameter. [Solution] In a heater wire having a core wire with a heating wire wound around the outer circumference of a core material and a covering layer covering the core wire, a filling member is interposed between the core wire and the covering layer, forming a region where the filling member is interposed between the core wire and the covering layer, and a region where a void is formed without the filling member being interposed between the core wire and the covering layer. The void is formed to extend from one end to the other end of the heater wire.

Description

Technical Field

[0001] The present invention relates to a heater wire provided with a coating layer on a core wire obtained by winding a heating wire around a core material.

Background Art

[0002] Conventionally, a heater wire having a structure in which a coating layer is provided on a core wire obtained by winding an electric wire around a core material has been used. When using the heater wire, at the end of the heater wire adjusted to the required length, the coating layer is often removed, and connection terminals for supplying power to the heating wire are provided.

[0003] When removing the coating layer, usually, after providing a cut line in the coating layer, the coating layer is moved along the length direction of the heater wire. However, when moving the coating layer, the inner peripheral surface thereof may come into contact with the heating wire, and the heating wire may be displaced. Since the heating wire is wound around the core material at a preset pitch in order to obtain a predetermined calorific value, the displacement of the heating wire may affect the performance of the heater wire.

[0004] Prior Art Document 1 describes a heater wire that is excellent in workability while suppressing the displacement of the heating wire when removing the coating layer by forming a void portion surrounded by the core material, the heating wire, and the coating layer that constitute the heater wire.

[0005] Thus, it is known that by forming a void portion inside the heater wire, the workability when removing the coating layer can be improved.

Prior Art Documents

Patent Documents

[0006]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0007] The object of the present invention is to provide a heater wire that can stably form a void inside and is also suitable for reducing its diameter. [Means for solving the problem]

[0008] The inventors of the present invention have diligently studied the structure of heater wires and have found a solution to the problem by interposing a filling member between the core wire and the filling layer in a heater wire having a core wire with an electric heating wire wound around the outer circumference of a core material and a covering layer covering the core wire. This creates a region where the filling member is interposed between the core wire and the covering layer, and a region where a gap is formed between the core wire and the covering layer without the filling member being interposed. [Effects of the Invention]

[0009] By adopting the above configuration, a stable void is formed that contributes to improved workability when removing the coating layer, and a heater wire suitable for miniaturization can be provided. [Brief explanation of the drawing]

[0010] [Figure 1] This is an example of a heater wire structure according to the present invention. [Figure 2] This is an example of the heater wire supplement member of the present invention. [Figure 3] This is an example of a heater wire structure of the present invention in which the filling member is spiral-shaped. [Figure 4] This is an example of varying the winding pitch of the heating element. [Figure 5] This is an example of a planar heater using the heater wire of the present invention. [Figure 6] This is an explanatory diagram of the adhesion strength test method. [Modes for carrying out the invention]

[0011] The present invention will be described with reference to Figure 1, which is an example of a basic embodiment. Figure 1 shows an example of a heater wire 1 of the present invention, which consists of a core wire 10, a covering layer 30 covering the core wire 10, and a filling member 20 interposed between the core wire 10 and the covering layer 30. The core wire 10 consists of a core material 11 and a heating wire 12 wound around the core material 11.

[0012] A distinctive feature of the present invention, as shown in Figure 1, is that a region in which a filling member 20 is interposed between the core wire 10 and the coating layer 30, and a region in which a void S is formed between the core wire 10 and the coating layer 30 without the filling member 20 being interposed, are formed.

[0013] The void S is a space formed by being surrounded by the core wire 10, the filling member 20, and the covering layer 30. Since there is a region around the area where the void S is formed where the filling member 20 is interposed between the core wire 10 and the covering layer 30, the filling member 20 functions as a spacer for forming the void S, and the void S can be stably formed inside the heater wire.

[0014] By forming a gap S along the entire length of the heater wire 1, the workability when removing the coating layer 30 can be improved.

[0015] To form a gap S along the entire length of the heater wire 1, the gap S should be formed so that it extends from one end to the other of the heater wire 1.

[0016] The state in which the void S extends from one end to the other of the heater wire 1 refers to a state in which the void S is formed continuously without interruption from one end to the other of the heater wire 1. Because the void S is formed continuously from one end to the other, the effect of the void S can be obtained even if the heater wire 1 is cut at any point along its length.

[0017] Examples of the void portion S extending from one end to the other end of the heater wire 1 include the spiral shape shown in FIGS. 2(a)-(b), the linear shape shown in FIGS. 2(c)-(d), the curved shape shown in FIG. 2(e), and the like. In FIGS. 2(a)-(e), the coating layer 30 is omitted to make the mode of the filling member 20 easier to understand.

[0018] Further, the number of the void portions S is not limited to one only, and a plurality of filling members 20 may be interposed on the outer periphery of the core wire 1 as shown in FIGS. 2(a)-(b) to form an arbitrary number of void portions S.

[0019] In the present invention, the spiral void portion S shown in FIG. 3 can be preferably used. Generally, the heater wire 1 is linear with a circular cross section, and uniformity is often required for the flexibility and heat generation characteristics.

[0020] In the case of the spiral void portion S, the region where the filling member 20 is interposed between the core wire 1 and the coating layer 30, and the region where the void portion S is formed without the filling member 20 being interposed between the core wire 1 and the coating layer 30 are present periodically in both the length direction of the heater wire 1 and the circumferential direction in the cross-sectional view. Therefore, the flexibility and the uniformity of the heat generation characteristics can be enhanced.

[0021] The spiral void portion S can be formed by winding the filling member 20 around the outer periphery of the core wire 1 at a predetermined pitch.

[0022] As the filling member 20 wound around the core wire 1, a flat member typified by a ribbon or a tape is preferable. If it is flat, a fleshy one can be used, so that an increase in the outer diameter of the heater wire 1 can be suppressed, and the void portion S can be stably formed by surface contact with the coating material 30.

[0023] The thickness of the filling member 20 is preferably about 0.03 to 0.20 mm, more preferably 0.05 to 0.10 mm. With a certain thickness, the void portion S can be stably formed, and by limiting the thickness, an increase in the outer diameter of the heater wire 1 can be suppressed.

[0024] When providing the gap S, the winding pitch P of the filling member 20 preferably satisfies the following relation (1). Here, d is the dimension of the gap S along the longitudinal direction shown in Figure 3, width ω is the width dimension of the filling member 20 in the winding state, R C The outer diameter R of the core wire 10 C π represents the ratio of a circle's circumference to its diameter (pi).

number

[0025] By setting the winding pitch P of the filling member 20 to satisfy relation (1), it is possible to wind the filling member 20 having a dimension d along the length direction of the void S onto the core wire 10. Because the filling members 20 have a dimension d along the length direction of the void S, they do not overlap and the thickness does not become excessive, thus suppressing an increase in the outer diameter of the heater wire 1.

[0026] The length d of the void S along its length can be arbitrarily set by those skilled in the art, but considering the stable formation of the void S, it is preferable to have a length of 5 mm or less, and more preferably 3 mm or less.

[0027] When removing the coating layer 30, it is more effective if the heating element 12 is pressed toward the core material 11 by the filling member 20.

[0028] One example of how the heating element 12 is pressed by the filling member 20 is a configuration in which at least a portion of the heating element 12 is embedded in the filling member 20. Specifically, one example is a configuration in which the heating element 12 is embedded to a distance A less than the diameter of the heating element 12, as shown in Figure 1, and preferably the distance A is 9 / 10 or less of the diameter of the heating element 12. By embedding 1 / 10 or more of the diameter of the heating element 12 in the filling member 20, a pressing force is generated by the filling member 20, which contributes to suppressing displacement of the heating element 12. The amount of embedding can be arbitrarily adjusted within the range that achieves the effects of the present invention.

[0029] From the viewpoint of suppressing displacement of the heating element 10, it is preferable that the winding direction of the reinforcing member 20 is opposite to the winding direction of the heating element 12. By having the winding direction of the reinforcing member 20 be opposite to the winding direction of the heating element 12, a decrease in pressing force can be suppressed.

[0030] The winding direction of the supplement member 20 (S-winding, Z-winding) is not particularly limited; the winding direction of the supplement member 20 should be set to match the winding direction of the heating wire 12.

[0031] The filling member 20 used for the heater wire 1 is preferably highly heat-resistant and highly flexible. Since the filling member 20 is used in a form that is in direct contact with the heating element 12, it is required to be made of a material that is highly heat-resistant and less susceptible to heat effects. High flexibility does not impair the flexibility of the heater wire 1 and allows for easy embedding of the heating element 12.

[0032] Furthermore, it is preferable that the filling member 20 is flame-retardant. By being flame-retardant, the upper limit of the temperature range of the heating wire 12 is widened, allowing the heater wire to be suitably used for various applications.

[0033] As an example of the filling material 20, fluororesins such as polytetrafluoroethylene (PTFE) or polyimide are suitable because they have high heat resistance, good flame retardancy, and low friction, and are also easy to remove.

[0034] In the heater wire 1, the coating layer 30 and the filler member 20 only need to have an adhesion force of 4N or more. If the adhesion force is 4N or more, the positional relationship between the filler member 20 and the coating layer 30 will be maintained. The adhesion force in this invention is described below.

[0035] Furthermore, considering the ease of removing the filling member 20, the coating layer 30 and the filling member 20 may be fused together.

[0036] In terms of the ease of removing the coating layer 30, a material with low friction properties is preferable. The lower the friction property, the less resistance there is when removing the coating layer 30, resulting in better workability.

[0037] Furthermore, it is preferable that the coating layer 30 has high heat resistance and flame retardancy. By having high heat resistance and flame retardancy, the upper limit of the temperature range of the heating wire 12 is widened, and the heater wire can be suitably used for various applications.

[0038] From the above perspective, a thermoplastic resin can be suitably used for the coating layer 30. In particular, a fluororesin having high heat resistance, flame retardancy, and low friction properties can be more suitably used.

[0039] Examples of fluororesins that constitute the coating layer 30 include PFA (tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer), FEP (tetrafluoroethylene-hexafluoropropylene copolymer), ETFE (ethylene-tetrafluoroethylene copolymer), and PTFE.

[0040] PTFE is particularly preferred as the fluororesin constituting the coating layer 30. PTFE is preferable for use in the present invention because it has high heat resistance and good flame retardancy, and is used as a heat source.

[0041] The core material 11 used in this invention can be a single-core core material such as a glass core or a rubber elastic core, or a core material made by twisting together multiple fibers such as glass fibers, polyamide fibers, or polyester fibers. From the viewpoint of heat resistance and the flexibility of the heater wire, a core material made by twisting together glass fibers is particularly preferable.

[0042] The heating element 12 used in this invention can be a resistance wire such as a nichrome wire, stainless steel wire, or copper-nickel alloy wire, and these resistance wires can be used as a single wire or in combination of multiple wires.

[0043] Furthermore, the winding pitch of the heating element 12 may be arbitrarily selected according to the desired amount of heat generated by the heater wire 1. However, for heating elements 12 with an outer diameter of approximately 0.02 to 0.26 mm, which are commonly used in general heater wires, a winding pitch of approximately 0.1 to 20.0 mm is preferably adopted.

[0044] In the present invention, the winding pitch of the heating wire 12 does not necessarily have to be constant. Depending on the desired amount of heat generated, the winding pitch of the heating wire 12 may be varied as shown in Figure 4.

[0045] The heater wire of the present invention can be used in a manner in which it is arranged and wound around an object to be heated, or in a manner in which it is arranged on a planar member 40 such as aluminum foil or aluminum plate as shown in Figure 5.

[0046] In this invention, adhesion force is defined as the tensile strength in the evaluation method shown below.

[0047] The heater wire 1 was cut to a length of 200 mm, and the coating layer 30 and the filling member 20 on one end were removed over a length of 50 mm. The heater wire 1 with the core wire 10 exposed at one end was used as a measurement sample, and the tensile strength of the coating layer 30 was measured.

[0048] Figure 6 shows the method for measuring tensile strength. The exposed core wire 10 is passed through a removal jig 50 having a hole larger than the outer diameter of the core wire 10 and smaller than the outer diameter of the coating layer 30, and one end of the measurement sample (exposed core wire 10) is fixed to the chuck of the tensile testing machine. Then, with the removal jig 50 fixed so as not to move, one end of the measurement sample is pulled vertically upward at a tensile speed of 500 mm / min using the tensile testing machine, and the obtained tensile strength is taken as the adhesion force.

[0049] The following describes an embodiment of the heater wire of the present invention.

[0050] [Example 1] A core wire 10 was obtained by winding a nichrome wire with an outer diameter of 0.06 mm, which serves as the heating element 12, in the longitudinal direction (S) at a pitch of 0.25 mm onto a glass core with an outer diameter of 0.8 mm, which serves as the core material 11.

[0051] A 3mm wide PTFE tape was used as a reinforcement member 20 around the outer circumference of the core wire 10, with a 2mm gap between the PTFE tapes, and wound in the Z direction. The PTFE tape used had a wall thickness of 0.08mm, and a load was set so that the width of the PTFE tape in the wound state was approximately 2mm.

[0052] The heater wire 1 of the present invention was completed by extruding PTFE as a coating layer 30 onto the outer circumference of the core wire 10 around which the replenishment member 20 was wound. The thickness of the coating layer 30 was set so that the outer diameter of the heater wire 1 was approximately 2.1 mm.

[0053] A long heater wire 1 was cut at arbitrary points to prepare five measurement samples. Each sample was 200 mm long and designated as Samples No. 1 to 5.

[0054] [Example 2] A heater wire 1 was fabricated with an outer diameter of 0.15 mm and the same configuration as in Example 1. As in Example 1, five measurement samples were prepared from the long heater wire 1 and designated as samples No. 6 to 10.

[0055] For each sample in Examples 1 and 2, the removeability, misalignment, and adhesion of the coating layer 30 were evaluated, and the results are shown in Table 1. For the removeability of the coating layer 30, a "○" was given if the coating layer 30 could be removed using a commercially available automatic processing machine used for removing coatings from wire terminals. For misalignment, a "○" was given if no misalignment was observed visually.

[0056] [Table 1]

[0057] In all samples from Example 1 and Example 2, the removal of the coating layer 30 was good, and no misalignment was observed.

[0058] Regarding adhesion, in all samples in Example 1 and Example 2, the adhesion strength was 4N or higher, confirming that the positional relationship between the filling member 20 and the coating layer 30 was maintained.

[0059] From the above, it was confirmed that the heater wire 1 of the present invention has a core wire 10 in which a heating wire 12 is wound around the outer circumference of a core material 11, and a covering layer 20 that covers the core wire 10, and a filling member 20 is interposed between the core wire 10 and the covering layer 30, forming a region in which the filling member 20 is interposed between the core wire 10 and the covering layer 30 and a region in which a void S is formed without the filling member 20 being interposed between the core wire 10 and the covering layer 30, thereby stably forming a void S inside the heater wire 1, and it was confirmed that this structure provides excellent removeability of the covering layer 30. [Industrial applicability]

[0060] The heater wire 1 of the present invention can be applied to various applications in which heater wires have been conventionally used, such as rice cookers and insulated containers. [Explanation of Symbols]

[0061] 1 Heater wire 10 core lines 11 Core material 12 Heating wire 20 Replacement member 30 Covering layer 40 Planar members 50 Removal jig S cavity d Dimensions along the length of the void

Claims

1. A heater wire comprising a core wire in which a heating wire is wound around the outer circumference of a core material, a covering layer covering the core wire, and a supplementary member interposed between the core wire and the covering layer, The region in which the filling member is interposed between the core wire and the coating layer, A heater wire characterized by having a region in which a void is formed between the core wire and the coating layer without the interposition of a filling member.

2. The heater wire according to claim 1, characterized in that the gap extends from one end to the other end of the heater wire.

3. The heater wire according to claim 2, characterized in that the filling member is wound around the core wire.

4. The heater wire according to claim 3, characterized in that the winding direction of the filling member and the core wire are opposite.

5. The heater wire according to claim 4, characterized in that the winding pitch P of the filling member satisfies the following relational expression (1). [Math 1] ω is the width dimension of the refill member in its wound state, R Ｃ The outer diameter of the core wire 、 d is the length of the gap along the longitudinal direction, and π is the ratio of a circle's circumference to its diameter (pi).

6. The heater wire according to claim 5, characterized in that the dimension d of the gap portion along the length direction is 3 mm or less.

7. The heater wire according to claims 1 to 6, characterized in that the filling member is a first thermoplastic resin.

8. A heater wire characterized in that the first thermoplastic resin according to claim 7 contains either polytetrafluoroethylene or polyimide.

9. The heater wire according to claim 8, characterized in that the coating layer is a second thermoplastic resin.

10. The heater wire according to claim 9, characterized in that the second thermoplastic resin is a fluororesin.

11. A heater wire characterized in that the fluororesin described in claim 10 is polytetrafluoroethylene.

12. A planar heater characterized by having a heater wire according to any one of claims 1 to 6 arranged on a planar member.

13. A planar heater characterized in that the heater wire described in claim 11 is arranged on a planar member.

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