KR810000976B1 - Apparatus for maintaining calibration of thermo-couple used in bushing for drawing glass fiber - Google Patents

Abstract

In combination with a metallic bushing for the drawing of glass fiber and a thermocouple connected to the bushing to sense bushing temperature, the thermocouple comprising dissimilar metallic leads connected to the bushing, at least one of which leads as the property of forming an alloy with the material of the bushing whereby the interface between the leads migrates, an improved method of maintaining the calibration of the thermocouple comprising extending the one lead directly from the bushing and over a length so closely adjacent to the bushing that the temperature of the lead over the length is substantially equal to the temperature of the bushing.

Description

Thermocouple calibration retainer used for glass fiber draw bushings

1 is a perspective view of a bushing using a thermocouple connection of the present invention, a sectional view of a bushing component, and a schematic diagram of a resistance heating control circuit for a bushing.

2A is a cross-sectional view of a conventional typical thermocouple connection newly connected.

FIG. 2B is a conventional connection cross section similar to that of FIG. 2A after making a connection. FIG.

Fig. 3A is a cross sectional view of the sacred pole connection of the present invention newly connected;

3B is a cross-sectional view of the thermocouple connection of the present invention after making the connection.

FIELD OF THE INVENTION The present invention relates to a thermocouple calibration retaining apparatus and method for use in glass fiber take-out bushings, in particular improved thermocouple connections using platinum / rhodium bushings of the type used for glass fiber withdrawal, more particularly bushings. It is about a connection that maintains its correction during its useful lifetime.

Conventionally, thermocouples have often been used to monitor the temperature of bushings used for the extraction of glass fibers. The bushing is connected to a controller which in turn is connected to a power transformer for supplying current to the resistance heating bushing. The thermocouple output is ideally used to keep the temperature of the dissecting sink on the controller constant.

Indeed, it has been found that conventional thermocouple control circuits do not maintain a constant bushing temperature. Rather, as the bushing ages, the circuit gradually raises the bushing temperature. This has the side effect of changing the physical properties (eg, fiber thickness) of the glass fibers being drawn out in turn. This also affects bushing yield.

Although conventional thermocouples can be recalibrated to fix the above problem, this method has a very difficult drawback in practice due to the gradual and continuous variation of thermocouple output.

The present invention is based on the finding that conventional correction problems arise due to the movement of the interface between different metals of the thermocouple. The aforementioned shift phenomenon is that one line of thermocouple is pure platinum or high purity platinum alloy, the other line of thermocouple is platinum / rhodium alloy (e.g. 87% platinum and 13% rhodium) and platinum / rhodium with bushing sinks relatively large This is explained by the fact that they are alloys (eg 80% platinum and 20% rhodium). In use, rhodium moves from the bushing to the platinum line of the thermocouple so that the thermocouple junction moves from the bushing to the cold zone. Moving the junction to the low temperature band will degrade the thermocouple output, allowing the bushing temperature to be read without correction.

The reason for moving the thermocouple junction to the low temperature band is that conventional thermocouple connections place thermocouple lines perpendicular to the bushing. Thus, the junction point inevitably moves from the bushing to the cold zone.

The conventional correction problem is avoided by lengthening the length of the thermocouple wire adjacent to the bushing so that the temperature of the thermocouple wire of the present invention is equal to the temperature of the bushing.

As a result, even if movement occurs, there is a junction in the band where the bushing temperature can be truly measured.

It is a primary object of the present invention to provide a thermocouple connection for use in an alloy bushing for drawing such as glass fiber, in which the correction of the thermocouple remains substantially constant for the useful life of the bushing. Another object of the present invention is to provide a thermocouple connection for use in a temperature control circuit for alloy bushings, where the circuit maintains the bushing temperature constant over the life of the bushing. Another object of the present invention is to provide a thermocouple connection that is directly connected to the alloy member to be monitored and does not require recalibration over time, and is directly connected to the alloy member and does not require recalibration over time. To provide a thermocouple connection, a further object is to provide a thermocouple controller that reduces the frequency of quality control inspections in the glass fiber manufacturing process. The present invention will be described in detail below with reference to the accompanying drawings.

1 is a perspective view of the metered thermocouple connection of the present invention with a bushing placed under a directly melted forehearth. The aforementioned pores and bushings are in the form described in my US Pat. No. 3,988,135, issued October, 1976. The lower part of the above-mentioned pore huers applies the layer of the refractory material which has the flow path 12, and becomes the flow block 10 which carried the platinum foil lining 14. As shown in FIG. The floating body 16 is supported by the removable material under the flow block 10 in parallel with the bottom part of a block. The bushing body is supported by a structure consisting of a corner member 18, which is connected to the side of the bottom surface of the bushing body to maintain the bushing body in an aligned position with respect to the flow path 12.

In the above example, the bushing body 16 forms a chamber 22 therein and includes a block 20 that opens through the top and bottom surfaces of the block. The chamber 22 is arranged in line with the oil path 12 when the bushing body is placed in position. The block 20 is made of refractory material and is lined with an alloy lining 24 of 80% platinum and 20% rhodium inside the passage 22. The orifice plate 26 extends outwardly from the bottom of the flow path 22 and is integrally connected to the lining 24. Plate 26, such as lining 24, is made of an alloy of 80% platinum and 20% rhodium. The detailed structure and operating mode of the bushing body 16 is described in the aforementioned US Pat. No. 3,988,135.

Nationwide terminals 28 and 30 are connected to both sides of orifice plate 26 to provide resistive heating of the plate. These terminals are connected to the power transformer 32 by leads 24 and 36. Power is supplied to the transformer 32 by the power supply 33. The variable rock machine 32 is controlled by the controller 37. Controllers, transformers, and electrode circuits are well known and provide resistive heat to orifice plate 26 to maintain its temperature substantially uniform. Lead 38 connects the controller to the transformer.

The thermocouple connection of the present invention is connected to the bushing (i.e., the platinum / rhodium element of the bushing body 16) to sense the temperature of the bushing close to the orifice plate and to supply the control signal to the controller 37. In the above example, the connecting means penetrates the orifices 40 and 42, the adjacent orifices 40, which loosen the lining 24, which is in close proximity to the orifice plate 26, generally at the center of the plate length. Platinum / rhodium alloy wire 44 of 87% platinum and 13% rhodium, pure platinum wire 46 through orifice 42, weld junction 48 between wires 44 and 46, each Welds 44a and 46a joining lines 44 and 46 to lining 24, and the outer surfaces of orifice plate 26 and dining 24 are proximate a predetermined length or more of Elongated portions 44b and 46b extending directly from lines 44 and 46 such that the temperature is substantially the same as that of junction 48.

The connection part of this invention was shown in FIG. 3A and 3B specifically. In this figure, the internal bushing temperature at the reception point 48 is denoted as T ₁ , and the temperatures of the stretched portions 44b and 46b are denoted as T ₂ . FIG. 3A shows the connection in a state where the interface between the different metals of the thermocouple is at the junction 48. FIG. 3B shows the connection under conditions after a certain period of time when the interface between the different metals of the thermocouple moves to the extension section 46b so that the temperature is T ₂ .

The movement shown in FIG. 3b shows the result of moving the rhodium to the platinum line 46 from the sink of the platinum rhodium alloy provided by the bushing. As a result of the movement, the point at which the temperature is sensed by the thermocouple is moved along line 46. This occurs because the temperature is sensed at the interface of the different metals of the thermocouple. Since the temperatures T ₁ and T ₂ are substantially the same as those of the present invention, this change in position does not cause misreading.

In one embodiment of the present invention, the orifice plate has a length of about 10 inches and the line portions 44b and 46b have a length of at least about half of that length (ie, about 5 inches). The space between the line portions 44b and 46b and the outside of the lining 24 is about 1/8 inch. When assembling the bushing, the space is maintained by inserting a glass oral spacer on the line. The line portion is located about 1/4 inch above the orifice plate 26 in the refractory of the block 200. The lead portions 44b and 46b are controlled by the connecting leads 50 and 52, respectively. ) Is connected.

2a and 2b show a conventional thermocouple connection. Although not shown, this connection can be connected to a control and transformer circuit similar to that of FIG. 1 to control the temperature of the bushing. The bushing lining wall 54 is shown in this figure as having a pair of thermocouple lines 56 and 58 extending therethrough. As shown in the embodiment of the present invention described above, the wall 54 is composed of an alloy of 80% platinum and 20% rhodium, the line 56 is 87% platinum and 13% rhodium, and the line 58 is Pure platinum. Lines 58 and 56 are joined at the melting point junction 60 in the bushing and welded to the inner surface of lining 54 by respective welds 56a and 58a.

Unlike the connection of the present invention, the elongated portion of the thermocouple wire, which is the conventional arrangement shown in Figs. 2a and 2b, generally extends vertically from the lining of the bushing. This stretched portion is represented by 56a and 58b, respectively. Figure 2b shows the state that occurs when rhodium moves from the bushing to line 56b as a result of the passage of time. As shown in the following figures, the shift occurs from the position of the junction 60 at the temperature T ₁ to a position separated from the lining 50 at the temperature T ₂ . The temperature T ₂ is slightly lower than the temperature T ₁ because the line 56b extends in the vertical direction from the bushing, so that the thermocouple output does not accurately represent the bushing temperature.

By using the conventional arrangement shown in Figures 2a and 2b, it was found that the temperature read from the thermocouple using a ＂R＂ type thermocouple decreased by 0.75 ° F per day. This is due to the reduced thermocouple output. Thermocouple outputs vary depending on the type of thermocouple used. Typical outputs at 2300 ° F are:

The useful life of the type bushing used here is about 9 months. Anisotropy of the interface between different metals of the thermocouple is between 1/4 and 1/2 inch during this period. Thus, by using extension portions 44b and 46b having a length of about 5 inches, the connection of the present invention provides a constant correction during the normal life of the bushing.

Although preferred embodiments of the present invention have been described above, the present invention is not limited to this embodiment. For example, the present invention may use a 'R', 'S' or 'B' type thermocouple, and the platinum / rhodium alloy of the bushing may vary depending on the embodiment. And alloying with 10% rhodium). In addition, the present invention has the property that at least one or more of any type of metal bushing and thermocouple wire has a property of forming an alloy with the bushing agent, so that the warp plane between the wires of the thermocouple moves. It can be seen.

Claims (1)

In hypothesizing a metal bushing for glass fiber drawing and a thermocouple connected to the bush to sense the bushing temperature, at least one of the different metal thermocouple wires connected to the bushing is alloyed with the bushing material at the place where the interface between these thermocouple wires moves. A thermocouple having a metal wire having a property of forming a wire, an interface between at least one of the thermocouple wires connected to the bushing and an extension portion of at least one of the thermocouple wires extending from the bushing, and the extension of the thermocouple stone substantially increases the temperature of the thermocouple stone. A thermocouple integrity holding device characterized by an improved thermocouple connection in proximity to the bushing such that

Images