JPH04190583A - Cylindrical heating element and heating method by use thereof - Google Patents

Abstract

PURPOSE:To secure flexibility, uniformity of heating and a set watt density for a cylindrical heating element by using flexible heating thread which contains discontinuous fiber of stainless steel at one portion of thread to be supplied to a bobbin and making adjustment of the watt density within the range of 0.01-2.0w/cm<2>. CONSTITUTION:A cylindrical heating element is braided by use of a flexible heating thread 23 in a part of a thread 21 supplied to a right-turning bobbin and in a part of a thread 22 supplied to a left turning bobbin. Moreover, the cylindrical heating element is provided as one whose watt density is 0.01-2.0w/cm<2>. It is therefore unnecessary to wind a resistance wire around a pipe when it is heated and kept warm, and the cylindrical heating element is operative when a watt density is within the range of 0.01-2.0w/cm<2>, so that it is possible to generate heat within the range from 25 to 300 deg.C under the atmosphere of ordinary temperature. It is thereby possible to secure flexibility and keep heating and warmness at a fixed watt density and at such a temperature as desired.

Description

[Detailed description of the invention] [Industrial application fields] The present invention relates to a heating method using a cylindrical heating element.

[Prior Art] Conventionally, it has been known to generate heat by passing a current through a resistor such as a nichrome wire having a large electrical resistance value, which is used as a heat generating element. However, since the metals used in these resistors lack ductility, they cannot be made into thin fibers, which limits their use as flexible linear heating threads. In other words, in order to heat an object to be heated such as a pipe using a resistor such as a conventional nichrome wire, it is necessary to wind the resistor in a spiral shape and then heat it by applying current to the resistor. Ta. However, the resistor is wound spirally around a heated object such as a pipe (
The work of counting =1 requires time and advanced technique.

In other words, it is wrapped around the object to be heated in a helical shape (in the case of 1) winding is done uniformly depending on the situation, such as the long length of the pipe, the fact that the pipe may be bent or used, the diameter of the pipe or the small diameter of the pipe, etc. It was difficult to wind the resistor around the wire, and in addition, there were restrictions such as having to work all at once because the first winding part would become loose, making it extremely difficult.

[Object of the Invention] The object of the present invention is to solve the problems of the conventional art and to provide a cylinder that can obtain a predetermined watt density by using a cylindrical heating element that has unprecedented flexibility and can generate heat uniformly. The purpose of the present invention is to propose a cylindrical heating element and a heating method using the cylindrical heating element.

[Structure of the invention] A portion of the yarn supplied to the right-handed hobbin and the left-handed bobbin, or a portion of the yarn supplied to either one of the bobbins, is a flexible heat-generating yarn containing discontinuous stainless steel fibers. This is a round braid made using a wattage density of 0.01 to 2.
It is a cylindrical heating element that can be adjusted in a range of Ow/cl, and the cylindrical heating element is used to cover an object to be heated, and the cylindrical heating element is connected to a predetermined resistor or a constant current generator. applied to a heating method using a cylindrical heating element characterized in that a constant current is applied to the cylindrical heating element to generate heat at a set watt density within the range of the watt density to heat the object to be heated. I'm coming.

The flexible heating yarn used in the present invention is a yarn that is a mixture of discontinuous fibers made of stainless steel and discontinuous fibers made of non-conductive fibers.

More specifically, the heat generating yarn used in the present invention is preferably 4 to 30 μm in diameter and 100 to 80 μm in fiber length.
Discontinuous fibers of stainless steel in the range 0 mm are used. The discontinuous fibers made of stainless steel are contained in an amount of 20 to 60% by weight based on the total weight of the heating yarn, and the discontinuous fibers made of non-conductive fibers are contained in an amount of 80 to 40% by weight based on the total weight of the heating yarn. It is a blended yarn formed using It is preferable that the number of discontinuous fibers made of stainless steel in the cross section of the blended yarn is 20 or more, and the twist coefficient of the blended yarn is 6,500 to 1.
3,500 is used. A cord yarn is formed by plying a plurality of the blended yarns and giving them a ply twist, the ply twist having a twist in the direction opposite to the twisting direction of the ply twist, and the ply twist coefficient and the ply twist coefficient is in the range of 0.5 to 1.50, and the electrical resistance value of the cord yarn is 0.05 to 10Ω.
/ cm, and the resistance value variation coefficient C% is C
■ A heat-generating cord yarn characterized by satisfying ≦10 is optimally used.

Specifically, ordinary synthetic fibers, recycled fibers, and natural fibers are used as the discontinuous fibers made of non-conductive fibers to be mixed with the discontinuous fibers made of stainless steel, but among them, fully aromatic polyamide is used. Bass is preferred because it has high heat resistance and will not deteriorate or catch fire even if the stainless steel discontinuous fibers generate heat and the temperature rises. As the externally heat-resistant fibers, those made of heat-resistant polymers such as polybenzimidazole, polyimide, and polyetherethergadon can be used. When blending the discontinuous fibers made of these non-conductive fibers with the discontinuous fibers of the stainless steel, the blending ratio is such that the discontinuous fibers of the stainless steel account for 20 to 20% of the total weight of the yarn.
A stainless steel discontinuous fiber containing 60% by weight is used, and it is preferable that the number of stainless steel discontinuous fibers is 20 or more.

Such a blended yarn can be manufactured by the process shown in FIG. FIG. 1 is a diagram illustrating the process of manufacturing a blended yarn used as a flexible heat generating yarn used in the present invention. In Figure 1, continuous stainless steel 1
1 and non-conductive continuous fibers 15 are fed to the roller 12 in a superimposed manner, and are cut between the rollers 13 and the fibers to form discontinuous fibers. At this time, it is preferable that the continuous stainless steel 11 and the non-conductive continuous fibers 15 are spread to a certain width and overlapped. The spacing between roller I2 and roller 13 determines the average fiber length of the discontinuous fibers, and for stainless steel fibers with an average fiber length of 800 mm, the roller spacing is ], 000 mm.
It can be obtained by Moreover, the count of the blended yarn can be determined by adjusting the speed ratio of the rollers 12 and 13. Preferably, the discontinuous fibers are those not shown in 14 of FIG. 1, but whose convergence is achieved by a compressed air nostle. Examples of the compressed air nostle include one that generates a swirling flow and one that entangles fibers with each other.

The cylindrical heating element of the present invention is formed of a circular braid, and the circular braid is composed of threads supplied to a clockwise bobbin and a counterclockwise bobbin, and has the form shown in FIG. be. FIG. 2 is a perspective view showing an embodiment of the cylindrical heating element of the present invention. It is braided using flexible heat generating yarn 23. The number of yarns supplied to the right-handed bobbin and the left-handed bobbin ranges from 2 to 72. A braided body organized with such a number range has a cylindrical or bag-like shape having a hollow portion with a converted inner diameter of 0.1 to 7.0 am. A cylindrical heating element is obtained by arranging the above-mentioned heating yarn in such a cylindrical body, but the heating yarn is used at a ratio of 10 to 100 with respect to the yarn supplied to the clockwise bobbin. used at a rate of %. The usage ratio for the yarn supplied to the counterclockwise bobbin is also the same, but the number of heat generating yarns supplied to the clockwise bobbin and the number of heat generating yarns supplied to the counterclockwise bobbin may be the same or different. Good too. Of course, the heating yarn can be supplied to both the right-handed bobbin and the left-handed bobbin, or it may be supplied to either one of them. Such a cylindrical heating element has a watt density of 0.01 to 2. Ow
/c♂.

The non-conductive yarn supplied to the right-handed bobbin and the left-handed hobbin is not particularly limited, and may be commonly used synthetic fibers, recycled fibers, or natural fibers. Among these, it is preferable to use wholly aromatic polyamide because it has high heat resistance and will not deteriorate or catch fire even if the temperature rises due to the flexible heating yarn. As the externally heat-resistant fibers, those made of heat-resistant polymers such as polybenzimidazole, polyimide, polyether ether kedone, etc. can be used.

The thus obtained cylindrical heating element is used to cover the object to be heated, the cylindrical heating element is connected to a resistor, and a constant current is applied to the cylindrical heating element to set the wattage within the range of the watt density. It is something that causes density heat generation.

Examples of the resistor include a current controller type (current limiter), a voltage control type (voltage regulator), a resistor using an IC, etc. Among them, a constant current generator is used. Things are convenient in terms of temperature control. FIG. 3 is a perspective view showing an example of implementing the method of the present invention. In Figure 3,
A pipe 31 that requires heat retention is covered with a cylindrical heating element 32, and a power source 34 and a constant current generator 35 are connected to a lead wire drawn out from the cylindrical heating element 32. The heated body has various lengths, and the cylindrical heating element can be cut to an appropriate length. In addition, when the pipe of the heated object is long, multiple heating elements are arranged in series,
A set temperature can be obtained by passing a constant current through each.

[Function of the Invention] The cylindrical heating element of the present invention has the following two configurations, so there is no need to wrap a resistance wire as in the conventional method when heating and keeping pipes warm. The cylindrical heating element can have a straw I/density in the range of 0.01 to 2.Ow/c♂, so it can be heated at 25 to 300°C in an environment at room temperature.
It is possible to generate heat in the range of

In addition, according to the method using the cylindrical heating element, the current flowing through the cylindrical heating element can be adjusted to a set current by varying the length of the cylindrical heating element or the shape of the pipe, or by connecting it with a resistor. This makes it possible to obtain a constant watt density, and when connected to a constant current generator, the set current can be changed as appropriate, allowing heating and keeping at a desired temperature.

According to the present invention, unlike the conventional method, even if the pipe has a complicated shape, it is good to cover the pipe with a cylindrical heating element when removing the pipe (=I' +). In this way, there is no need to wrap the resistance wire along the pipe, which greatly improves the work.Also, even if the diameter of the pipe becomes thinner, or conversely if it becomes thicker. Also, the diameter of the cylindrical heating element can be changed by changing the number of threads constituting the cylindrical heating element, so there is no need for skilled workers.

Furthermore, these operations can be performed by simply adjusting the length of the cylindrical heating element (cutting the length of the cylindrical heating element) according to the length of the pipe, resulting in a significant improvement in operations.

[Example] Polymetaphenylene isophthalamide long fibers ( Approximately 2,700 bundles of denier 2 de) are piled up and fed to the device shown in Fig. 1, and the distance between the rollers is set to 1, QOOn+m in the tension cutting area consisting of rollers 2 and 3. After setting, the yarn was further shredded 20 times between both rollers, and the average fiber length was approximately 310 m1.The blend ratio of polymetaphenylene isophthalamide fiber was 50%, and the number of discontinuous stainless steel fibers was approximately 75 wood. (1・−taldenir+5
00 dQ) was obtained. As a first twist to the blended yarn, Z 50
After applying a twist of 0 T/H and doubling the two blended yarns,
A flexible heating yarn was obtained by using a ply twist of 5355 T/M as the ply twist. Aramid spun yarn (1-tal denier: 1.000 dO) using short fibers made of polymetaphenylene isophthalamide prepared separately from the flexible heat generating yarn
) are supplied to a clockwise bobbin at a ratio of 1:5, and 24 aramid spun yarns are supplied to a counterclockwise bobbin to form a cylindrical heating element with an inner diameter of approximately 0.8 cm (electrical resistance value 40Ω/ m
) was obtained.

[Example 2] The cylindrical heating element obtained in Example 1 was used to cover a two-shaped pipe, and a current of 0.8 A was applied using a current limiter to produce a wattage of 0.115 v/cll. The pipe was heated with an exotherm of density.

[Example 3] Using the flexible heat-generating yarn and the aramid spun yarn prepared in Example 1-, a clockwise bobbin was supplied with 24 pieces at a ratio of 5:5.
24 cylindrical heating elements with an inner diameter of approximately 0.8 cm (electrical resistance value 20 Ω/m) are supplied to the counterclockwise bobbin at a ratio of 1.5.
I got it.

[Example 4] Using the cylindrical heating element obtained in Example 3 to cover a two-shaped pipe and using a voltage regulator] 6A of current was applied to give a watt density of 0.22 w/at. The pipe was heated by generating an exotherm.

[Example 5] The cylindrical heating element obtained in Example] was used to cover a double-shaped pipe as shown in Figure 3, and a constant current generator was connected to the pipe to supply a current of 0.8 A. to generate heat with a watt density of 0.115 w/cl, and after 1 hour operate the constant current generator to apply a current of 0.4 A to generate heat with a watt density of 0.029 w/c♂ to change the pipe to a different type. Heated at temperature.

[Brief explanation of drawings]

FIG. 1 is a diagram illustrating the process of manufacturing a blended yarn used in the flexible heating yarn of the present invention, FIG. 2 is a perspective view showing an embodiment of the cylindrical heating element of the present invention, and FIG. 3 1 is a perspective view showing an example of implementing the method of the present invention; FIG. 23... Flexible heating thread 31... Heated body 32... Cylindrical heating element 35... Constant current generator Fig. 2 Fig. 3

Claims (3)

[Claims] (1) In a circular braid composed of a thread supplied to a clockwise bobbin and a thread supplied to a counterclockwise bobbin, a part of the thread supplied to the clockwise bobbin and the counterclockwise bobbin, or either one of them A flexible heating yarn containing discontinuous stainless steel fibers is used as part of the yarn supplied to the bobbin, and the watt density is adjustable in the range of 0.01 to 2.0 w/cm^2. A cylindrical heating element. (2) One of the threads supplied to the clockwise bobbin and counterclockwise bobbin
A circular knitted fabric using a flexible heat-generating yarn containing discontinuous stainless steel fibers as part of the yarn supplied to the bobbin, or one of the bobbins, and having a watt density of 0.01.
A cylindrical heating element that can be adjusted in the range of ~2.0w/cm^2 is used, the heated object is covered with the cylindrical heating element, and a constant current is applied by connecting the cylindrical heating element and a resistor. A heating method using a cylindrical heating element, characterized in that the cylindrical heating element generates heat at a set watt density within the range of the watt density to heat the object to be heated. (3) One of the threads supplied to the clockwise bobbin and counterclockwise bobbin
A circular knitted fabric using a flexible heat-generating yarn containing discontinuous stainless steel fibers as part of the yarn supplied to the bobbin, or one of the bobbins, and having a watt density of 0.01.
A cylindrical heating element that can be adjusted in the range of ~2.0w/cm^2 is used, the heated object is covered with the cylindrical heating element, and a constant current generator is connected to the cylindrical heating element to generate a constant current. A heating method using a cylindrical heating element, characterized in that the cylindrical heating element is heated by applying electricity to the cylindrical heating element to generate heat by changing a set watt density within the range of the watt density.