JPH04237987A - Sheet-shaped heating element and heating element-buried object - Google Patents

Abstract

PURPOSE:To improve workability, uniformly heat, and simply adjust the heating temperature by leno-weaving an extensible required conductive weft yarn and a nonconductive warp yarn into an extensible woven fabric. CONSTITUTION:An extensible conductive weft yarn 1 entangled with a wrinkled extensible fiber thread 6 made of nonconductive fibers and a conductive thread 7 longer than the extended length of the thread 6 bent into a spiral or corrugated shape and a nonconductive warp yarn 3 are leno-woven to generate an extensible woven fabric 3. Electrodes 4, 5 conducting both end sides of the yarn 1 are provided at both edge sections in the horizontal width direction of the fabric 3, and metallic thread-shaped bodies 8 are woven at edge end sections of the fabric 3 to form a sheet-shaped heating element. It can be closely stuck to a complex stereoscopic face without being finely cut, the workability is improved, the whole object face can be uniformly heated with no complex electric wiring, and the heating temperature can be simply adjusted.

Description

[Detailed description of the invention]

0001

[Industrial Application Field] The present invention has the form of a stretchable braided cloth, and is suitable for use, for example, in manufacturing molds equipped with mold heating means for molding glass fiber reinforced plastics. The present invention relates to a suitable sheet-like heating element and a heating-element-embedded article in which this sheet-like heating element is embedded or attached.

0002

[Prior Art] For example, bathtubs, boats, etc. made of glass fiber reinforced polyester resin (FRP) are prepared by hand lay-up method, spray-up method, or resin transfer method.
In the case of molding by a molding (RTM) method or the like, a mold heating means is generally attached to the mold in order to accelerate the curing reaction of the polyester resin raw material having reactive curability. This mold is also often made of FRP. As the above-mentioned heating means, pipes for passing steam or hot water, sheet-like electric heaters made of braided conductive fibers such as carbon fibers, etc. are used, and these are generally buried or attached to the mold wall. I came. and,
When burying the above-mentioned pipes, it is necessary to use pipes with a diameter of at least 8 mm to avoid increasing the flow resistance of steam or hot water, so the spacing between adjacent pipes will inevitably widen and the mold wall A problem occurs in which the heating temperature distribution becomes uneven. Therefore, metal powder with good thermal conductivity, such as aluminum powder or iron powder, has been mixed into the molding material. In addition, when embedding a non-stretchable sheet-like electric heater such as carbon fiber cloth in a mold wall with a complex three-dimensional shape, the heater must be cut into small pieces to follow the uneven surface of the mold. , power supply wiring was performed for each segment.

0003

[Problems to be Solved by the Invention] However, the method of embedding the pipe in the mold wall not only increases the production cost of the mold, but also makes the mold extremely heavy due to the increase in weight due to the inclusion of metal powder, which makes it difficult to perform molding. This method had major drawbacks, such as poor workability and the need for a steam or hot water generator. If the temperature distribution on the mold wall is uneven, the curing state of the raw material resin within the mold will be uneven, resulting in uneven stress distribution in the molded product and failure to obtain the required product strength. do. Furthermore, if a mold is repeatedly heated and cooled with uneven temperature distribution, stress and strain due to uneven thermal deformation will occur repeatedly, accelerating the fatigue of the mold material and significantly shortening the mold life. . On the other hand, molds with embedded sheet electric heaters are easy to use as long as you have a power outlet, and the molds are lightweight, making them easy to work with and advantageous in reducing production costs. However, on the other hand, in order to embed or attach a conventional non-stretchable sheet-shaped electric heater to the mold wall along the mold surface with a complex uneven shape, it takes time and effort to cut the heater into small pieces. Each heater piece of different size has a different electrical resistance value, so in order to uniformly heat the entire mold wall, the number of power supply wires not only increases significantly, but also the electric resistance of each heater piece. It becomes necessary to change the voltage applied to each piece, and the power supply wiring becomes extremely complicated. Furthermore, if a conventional non-stretchable sheet-shaped electric heater is forced to fit onto an uneven surface, there is a high possibility that the sheet-shaped heaters will overlap in pleats and short-circuit when buried. However, if a stretchable sheet-shaped electric heater were developed, the above-mentioned trouble of cutting into small pieces and the associated troublesome power supply wiring would be greatly saved. Therefore, an object of the present invention is, for example, when used as a heating means for the above-mentioned synthetic resin mold, it can be brought into close contact with a construction surface having a complex three-dimensional shape without having to be cut into small pieces, and has excellent workability. The entire surface to be heated can be heated evenly without complicated electrical wiring, and the heating temperature can be easily adjusted, making it suitable for use in various fields other than synthetic resin molds. An object of the present invention is to provide an electric heating type sheet-like heating element and a heating element embedded article.

0004

[Means for Solving the Problems] In order to achieve the above object, a sheet-like heating element according to the present invention is provided by bending elastic fiber yarn 6 made of non-conductive fibers into a crimped form in a spiral or wavy form. Both sides in the width direction of a stretchable knitted fabric 3 made by weaving a stretchable conductive weft 1 intertwined with a conductive thread-like body 7 and a non-conductive warp 2 by means of a twining weave or the like. The structure is such that electrodes 4 and 5 are provided at the edges to connect the ends of each of the conductive weft threads 1 to each other. The length of the conductive filament 7 is set to be longer than the length when the stretchable fiber yarn 6 is fully stretched. The electrodes 4 and 5 are connected to the stretchable knitted fabric 3.
It is preferable to form the metal thread-like body 8 by weaving it into the edge portion of the plate. Further, the heating element embedded article according to the present invention has an arbitrary three-dimensional shape or planar shape, and has a structure in which the sheet-like heating element is embedded or attached to the body.

[0005]

[Function] A conductive weft yarn 1 with elasticity, in which a conductive thread body 7 bent in a spiral or wavy manner is intertwined with an elastic fiber yarn 6 made of crimped non-conductive fibers; The stretchable knitted fabric 3 made by twining or weaving the warp threads 2 that do not have any elasticity can be easily attached to follow the concave shape of the construction surface, so it does not have the conventional sheet-like shape that does not have stretchability. Unlike heating elements, there is no need to cut it into small pieces, and power supply wiring can be easily done. In addition, since the electric resistance value between the electrodes 4 and 5 provided on both horizontal edges of the sheet-like heating element is constant, even if the sheet-like heating element is cut into arbitrary lengths in the vertical direction, the unit of each section is The amount of heat generated per area is the same as long as the voltages applied between the two electrodes 4 and 5 are equal, and the power supply wiring is significantly simplified. By connecting each segment in parallel, the power supply voltage can be increased. By simply moving it up and down, you can freely adjust the heating temperature while keeping the entire surface to be heated uniformly heated.

[0006]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. The sheet-like heating element A according to the present invention shown in FIG. 1 is made by intertwining conductive fiber yarns 7 bent in a spiral or wavy manner with elastic fiber yarns 6, and weft yarns 1 that serve as heater wires. Electrodes 4 and 5 are provided at both edges in the width direction of a stretchable knitted fabric 3 woven with non-conductive warp threads 2 using a weaving method such as a leno weave, extending over the entire length of the edges. The material in this example is woven into a long material with a width of 30 cm. As shown in an enlarged view in FIG. 2, the conductive weft thread 1 is made of an elastic fiber thread 6 having a length of 30 cm in a shrunken state, which is made by subjecting a polyester fiber thread (twisted thread) to a well-known crimp process. It has a structure in which a conductive filament 7 made of stainless steel and having a thickness of 20 microns and a length of 50 cm is wound helically. The length of the conductive filament 7 is set to be longer than the length of the elastic fiber thread 6 when it is completely stretched. The warp yarns 2 are made of twisted yarns made of polyester fiber, and serve as a constituent material of the stretchable knitted fabric 3 and as a spacer that separates adjacent conductive weft yarns 1 from each other at a predetermined interval. In this embodiment, the electrodes 4 and 5 are made by densely weaving a plurality of metal thread-like bodies, for example, ultra-fine copper wires 8, into warp-like threads with a width of about 5 mm at both edges in the width direction of the sheet-like heating element A. As a result, it is formed into a belt shape.

In this embodiment, 84 conductive weft threads 1 are woven per 10 cm of warp thread 2, and the width is 30 cm.
The sheet-like heating element A having a length of 10 cm exhibited an electrical resistance value of about 8 ohms per 10 cm of length. This sheet-like heating element A,
After applying an arbitrary level of voltage between both electrodes 4 and 5 for 30 seconds at room temperature of 20 ° C. on a test piece buried at a depth of 3 mm from the surface of a 10 mm thick FRP board. When the surface temperature was measured, the data shown in Table 1 was obtained.

[Table 1] According to the above data, the FRP mold for molding FRP generally maintains the mold temperature at 60 to 90°C during molding, so the above sheet-shaped heating element A is suitable for the FRP mold. It was confirmed that it is suitable as a heating heater.

[0008] Next, an embodiment of a heating element embedded article incorporating the sheet-like heating element A will be described with reference to FIGS. 4 and 5. The heating element embedded article of this example is made of FRP
The same F
This is a heater-embedded mold B made by RP. The procedure for manufacturing the heater-embedded mold B is substantially the same as that for a mold made by embedding a conventional sheet-shaped electric heater made of carbon fiber. 4 and 5 show the outer mold of a heater-embedded molding mold B that is divided into two parts: the inner and outer parts. To create this heater-embedded mold B by the hand lay-up method or spray-up method, a gel coat layer of polyester resin is applied to the surface of the mother mold (not shown), and then the surface is coated as shown in FIG. A sheet-like heating element A having a total of four meshes may be attached to cover the entire surface of the peripheral wall and bottom wall of the matrix, and an FRP layer may be formed in a laminated manner on the outside thereof. When performing this attachment, as can be understood from FIG. 5, the sheet-like heating element A is considerably Because of its elasticity, it can be attached to the complex uneven surface of the gel coat layer without having to cut it into small pieces to make it easier to adapt to the uneven curved surface, unlike conventional sheet electric heaters made of braided carbon fiber threads. . Therefore, Figure 5
As shown in FIG. 2, the sheet heating element A can be embedded over the entire surface of the mold wall of the heater-embedded mold B at a uniform depth close to the inner wall surface.

As shown in FIG. 5, if the lead wires 9 connected to the respective electrodes 4 and 5 of the four sheet-like heating elements A are connected in parallel to the power cord 10, each sheet-like heating element Since the voltages applied between the electrodes 4 and 5 of body A are the same, and the electrical resistance values of each conductive weft 1 are the same, each sheet-like heating element A has a length in the longitudinal direction. Regardless of the size, the amount of heat generated per unit area is the same. However, since the conductive weft threads 1 are closely arranged parallel to each other with extremely narrow intervals of 1 mm or less, each sheet-like heating element A generates heat evenly over its entire surface. Furthermore,
Each sheet-like heating element A can be easily attached to the gel coat layer in close contact with the gel coat layer as described above, so it can be embedded at a uniform depth near the inner wall surface of the heater-embedded mold B. The entire wall can be heated extremely evenly. Moreover, if the voltage of the power source to which the power cord 10 is connected is raised or lowered by a variable slide transformer, etc., the sheet-like heating element A
The heat generation temperature of the heater-embedded mold B, and hence the mold temperature of the heater-embedded mold B, can be adjusted very easily.

In the above structure, the material of the conductive filament 7 may of course be selected from other conductive materials such as metals other than stainless steel, and the method for forming the electrodes 4 and 5 may also be changed, for example. , the material, thickness, and length of each component such as the warp 2 and the stretchable fiber yarn 6, or the stretchable knitted fabric 3 can be changed as appropriate, such as by providing a coating layer of a conductive coating agent.
The method of weaving, etc. may be appropriately selected depending on the use of the sheet-like heating element A. In addition to being used as a heating means for molds for molding synthetic resins such as FRP, the sheet-like heating element A according to the present invention can also be used, for example, as a flat panel-like body as a component of buildings or various equipment, or as a complex heating element. The surface heating element can also be used as a surface heating element to be embedded or attached to articles such as housings having an uneven shape, and its good workability and usability are fully exhibited.

[0011]

Effects of the Invention As is clear from the above explanation, the stretchable sheet-like heating element according to the present invention and the heating element-embedded article incorporating this sheet-like heating element have practical advantages as listed below. It has excellent effects. (a) Because it is highly elastic, it can be used on construction surfaces with complex uneven shapes, without having to be cut into pieces to match the curved surface shape, unlike conventional carbon fiber sheet electric heaters. It can be applied efficiently to this uneven construction surface in close contact. (b) Therefore, compared to conventional sheet-shaped electric heaters, the power supply wiring can be done much more easily. (c) The electrical resistance value in the width direction of the sheet-like heating element is:
It is constant regardless of its expansion/contraction state, so even if it is cut into sections of arbitrary length in the longitudinal direction, as long as both electrodes of each section are connected in parallel to the power cord, the unit area of each section is The amount of heat generated per unit is constant, and the power supply wiring to uniformly heat the entire construction surface can be extremely simplified. (d) Of course, the temperature of the heated surface can be raised or lowered by simply raising or lowering the power supply voltage of the power cord using a variable slide transformer or the like. (e) By using the sheet-like heating element of the present invention, it is possible to manufacture a heating element-embedded article, such as a synthetic resin mold equipped with a heating means, lightweight and at low cost, and the temperature of the mold can be easily adjusted. , and can be done freely.

[Brief explanation of the drawing]

FIG. 1 is a partial perspective view showing a sheet-like heating element according to an embodiment of the present invention.

FIG. 2 is a partially enlarged view of the conductive weft yarn of the same as above.

FIG. 3 is a partially enlarged plan view of the same stretchable knitted fabric.

FIG. 4 is a partially cutaway perspective view showing an example of a sheet-shaped heating element embedded article according to the present invention.

FIG. 5 is a longitudinal cross-sectional view taken along line XX in FIG. 4, also showing power supply wiring.

[Explanation of symbols]

A Sheet-like heating element B Heater embedded mold (heating element embedded article) 1 Conductive weft 2 Warp 3 Stretchable knitted fabric 4, 5 Electrode 6 Stretch fiber thread 7 Conductive thread 8 Ultra-fine copper wire (metal) filament) 9 Lead wire 10 Power cord

Claims (4)

[Claims] 1. A conductive weft yarn 1 having elasticity, in which a conductive filament body 7 bent in a spiral or wavy manner is intertwined with a crimp elastic fiber yarn 6 made of non-conductive fibers; The electrically conductive weft threads 1 are attached to both edges in the width direction of a stretchable knitted fabric 3 made by twining the non-conductive warp threads 2.
1. A sheet-like heating element characterized in that electrodes 4 and 5 are provided to make each one end side of the element conductive to each other. 2. The sheet-like heating element according to claim 1, wherein the electrodes 4 and 5 are formed by weaving metal threads 8 into the edge portions of the stretchable knitted fabric 3. 3. The sheet-like heating device according to claim 1, wherein the length of the conductive filament 7 is set to be longer than the length when the stretchable fiber yarn 6 is fully stretched. body. 4. The sheet-like heating element according to any one of claims 1 to 3, having an arbitrary three-dimensional shape or planar shape, is embedded or attached to the body of the heating element. Items with buried heating elements.