JPH0380250B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION a. Field of Industrial Application The present invention is a consumable plug-in unit for an immersion thermocouple for temperature measurement of melts, comprising a porcelain cylindrical configuration that can be inserted coaxially into a paper tube of a measuring lancet. a quartz insulating tube bent in a U-shape and fixed at the leg of the U on the side of the molding element facing the melt and further protected by a cap; The insulating tube is provided with a contact member located on the opposite side of the melt, which accommodates a compensating conductor for transmitting an electric signal and which can be inserted into a contact bush of a measuring lancet, and the insulating tube accommodates a thermoelectric junction of a thermocouple serving as a temperature sensor. The present invention relates to a consumable plug-in unit for an immersion thermocouple, in which the portions of the thermocouple extending from both legs of the insulating tube are connected to the compensating conductor.

In addition, in this specification, "molten material" means molten steel etc. which are the object of temperature measurement.

B. PRIOR ART Consumable plug-in units for thermocouples are widely used throughout the world, especially for measuring bath temperatures in molten steel. The single disposable use of immersion thermocouples results in a large consumption of precious metals, especially platinum and platinum-rhodium. In order to shorten the precious metal conductor,
A thermal immersion sensing device is used which is provided with a compensating wire, in particular made of copper, in a plug-in unit between the insulating tube and the contact element.

DE 15 73 233 A1 discloses a plug-in unit for immersed thermocouples with a compensating conductor welded or soldered to the thermocouple conductor projecting from the leg of an insulating tube. In this known measuring head, the lower part of the leg of the insulating tube, the part of the thermocouple conductor protruding from the insulating tube, the compensating conductor, the welded or brazed points of said conductor and part of the contact element are located in the cement. embedded in. A material electrically insulating the conductor is provided between the conductor and the cement, in which case there is no contact with the conductor at any point in the cement.

This design of the plug-in unit of the immersion thermocouple has the disadvantage that when connecting the thermocouple conductor to the compensation conductor, welding or brazing defects may occur which can lead to erroneous measurements. In this case, it is technically difficult to reliably connect metals with chemically and physically different properties, as is the case, for example, when platinum and platinum-rhodium are brought into contact with copper. The difficulty of connecting conductors is made even more difficult by small conductor diameters, such as in the case of compensation conductors, which typically have a diameter of 0.6 mm, and thermocouple conductors, which have a diameter of 0.2 mm.

In the case of the above-mentioned method of welding and connecting conductors, changes in the material structure also have an unfavorable effect on the transmission of measured values.

Another disadvantage of this known measuring head is that the insulation of the conductor from the outlet of the insulating tube leg to the entrance to the contact element requires assembly effort. In that case, a gap is created between the end face of the insulating tube and the side of the contact element facing towards the insulating tube, which gap prevents moisture from penetrating the insulating jacket from the cement. do not have. As a result, measurement errors occur due to the formation of contact potential differences.

DE 15 39 299 A1 discloses a plug-in unit for an immersion thermocouple, which comprises a porcelain cylinder-shaped part that can be plugged in coaxially with the paper bushing of the measuring lancet, and which is equipped with a temperature-sensing device. It has an insulating tube for accommodating it and a contact support which can be inserted into the contact socket. In this known plug-in unit,
The thermocouple wires are threaded through the sheath-shaped contact support, with one thermocouple conductor bent at the center of the sheath-shaped contact support, and the other thermocouple conductor bent at the head of the sheath-shaped contact support. and a member sufficient to provide a contact force provides a repulsive force.
The pod-shaped contact carrier can be inserted into the contact socket. The contact socket includes a contact ring that contacts each thermocouple lead.

A disadvantage of this plug-in unit is the high consumption of precious metal conductor due to the required length of the thermocouple conductor from the thermoelectric junction of the thermocouple to the contact support.

When inserting the contact carrier into the contact socket, significant friction occurs between the contact socket and the thermocouple conductor. The disadvantage is that it requires the use of relatively thick thermocouple wires with sufficient tensile strength.

A disadvantage in this known plug-in unit is also the complicated construction of the contact socket, which has a ring with the length of the wrapped end of the thermocouple wire to provide the contact force.

c. Problem to be Solved by the Invention The basic object of the invention is to minimize the material consumption of precious metals in the consumable plug-in units of thermocouples, in which case the thermocouple conductors constituting the thermocouple and the To provide a connection part between a compensating conductor wire which is extremely thinner than a conductor wire and can be made of precious metal and which is as short as possible, which is easily manufactured, the basic material does not deteriorate, and the contact is reliable.

d. Means for solving the problem This object is achieved by the features indicated in the essential features of claim 1. Preferred embodiments of the invention are indicated in the dependent claims.

In the case of the immersion thermocouple plug-in unit according to the invention, the thermocouple conductor has a diameter of 0.05 mm and protrudes slightly at the leg of the insulating tube. Each end of the thermocouple wire is threaded through an internal bore of the bushing to the side of the bush facing away from the insulating tube. In this way, the precious metal conducting wire can be shortened. In the connection according to the invention, 0.03
Precious metal conductors with a diameter of up to mm can be used. By doing so, the consumption of platinum and rhodium is significantly reduced. At present, reclaiming precious metals is too expensive.

By reducing the diameter of the thermocouple wire,
A short measurement time to know the temperature can be appropriately obtained. Measurement time is reduced by 1 to 2 seconds. This corresponds to about 1/3 of the current measurement time.
In this case, wear and tear on various parts of the measuring lancet, for example on the paper tube, can be reduced. This is because the immersion time of this portion into the melt is shorter. In addition, the wall thickness can be reduced and the material can be appropriately saved in the design.

By using the plug-in unit according to the invention with a bush as the connection point for the thermocouple conductor and the compensation conductor, the assembly operation can be carried out completely mechanically. In this case, it is a great advantage that a reliable connection point for transmitting the measurement signal is created with a connection point that is simple to assemble and can be easily controlled.

In a preferred embodiment of the plug-in unit, the bush is accommodated in a contact member which is releasably connected to the lancet. The bushing and the contact members are made of the same material, for example heat-resistant PVC. The molding and bonding of the bushing and the contact member are designed such that the conductor wires do not come into contact with the refractory material filled into the molded member. This has the advantage that moisture, which has a negative influence on the measured values due to the formation of contact potential differences, cannot reach the conductor.

The bushing is made of a rubber elastic material, and its inner diameter is equal to or slightly smaller than the outer diameter of the compensation conductor.

For assembly, a compensating conductor whose tip does not damage the rubber-elastic material is inserted into the internal hole of the bushing, which is designed to connect the thermocouple conductor and the compensating conductor, over the entire length of this hole. It will be passed over.
In this case, the noble metal conductor located in the internal bore is pressed sufficiently against the inner surface of the bushing on the one hand and against the outer surface of the compensating conductor on the other hand. The repulsive force of the rubber-elastic material of the bushing is designed to facilitate the passage of the compensating conductor into the internal bore. In that case, the pressing force is such that sufficient total contact occurs between the thermocouple conductor and the compensation conductor.

Due to the short length of the bushing, only small frictional forces occur for a short time between the compensation conductor and the thermocouple conductor when the compensation conductor is passed through. In that case, no cracking of the thermocouple copper wire occurs.

The structure of the connection point is extremely simple and consists exclusively of a bushing that can be manufactured economically in its original form, a compensating conductor wire that is not machined up to the chamfered edges, and a thermocouple conductor wire that is slightly cut off after being inserted into the bushing. ing.

e Examples Examples of the invention are illustrated. The description of the plug-in unit of the invention corresponds to the description of its assembly sequence.

Inside the U-shaped insulating tube 21, there is a thermoelectric junction 11 constituting a thermocouple. The thermocouple conductor wires, that is, the platinum wire 12 and the platinum rhodium wire 13 protruding from the insulating tube 21 at the leg end 22 are passed through the bush internal hole 32 of the bush 31 and are inserted into the end surface 36.
It is bent so that it touches the

Each leg end 22 is fitted into a bushing 31 up to the bottom surface 33 of its extension 34 .
4 surrounds the insulating tube 21.

A compensation conductor 14 made of a material having the same thermoelectric properties as the thermocouple conductors 12 and 13 is connected to the thermocouple conductors 12 and 1.
3 is passed through the bushing internal hole 32 from the opposite direction. Thermocouple conductor 12, which facilitates the insertion of the conductor.
In order to avoid damage to the compensation conductor 13, the compensating conductor 14 has a particularly frusto-conical chamfered corner on its end face.

The bushing 31 has a chamfer 35 at its hole opening to facilitate insertion of the thermocouple into the hole.

The compensating lead wire 14 is passed through the conduit of the contact member 41, and the bush 31 into which the insulating tube 21 is fitted is
It is inserted into the hole 42 of the contact member 41.

Next, the contact member 41 is fitted into the molded member 24 coaxially with the insulating tube 21 . The empty interior space 25 of the molded member 24, which is not filled by the contact member 41, the bush 31 and the insulating tube 21, is filled with a refractory material.

The open end of the cap 23, which surrounds and protects the insulating tube 21, is inserted into the hole 26 provided on the side of the molding element 24 facing the melt.

Once the plug-in unit has been assembled in this way, the contact member 41 is inserted into the contact bush 52 of the measuring lancet. The contact member 41 can be locked onto the contact bush 52 by deformation of the resilient plug in the upper part of the contact member.

The compensation conductor 14 is bent at the upper end of the contact member,
It is guided along the outer surface of the contact member and further above the lancet as shown by the dashed line in FIG. 1, and finally reaches the temperature signal input terminal of the control device.

[Brief explanation of drawings]

FIG. 1 is a side sectional view showing one embodiment of the present invention, and FIG. 2 is a side sectional view of a bush constituting the apparatus shown in FIG. 11... Thermocouple junction, 12... Thermocouple lead wire (platinum lead wire), 13... Thermocouple lead wire (platinum rhodium lead wire), 14... Compensation lead wire, 21... Insulated tube, 22
... Leg end, 23 ... Cap, 24 ... Molded member, 25 ... Internal space, 31 ... Bush, 3
2...butsu internal hole, 33...bottom of the expansion part,
34... Extension portion, 35... Chamfer, 36... End face, 41... Contact member, 51... Paper tube, 52...
Contact information.

Claims (1)

[Scope of Claims] 1. A consumable plug-in unit for an immersion thermocouple for temperature measurement of melts, comprising a paper tube 5 of a measuring lancet.
Porcelain cylindrical shaped member 24 coaxially insertable into 1
, a quartz insulating tube 21 bent in a U-shape, fixed at the leg of the U on the side of the molding member facing the melt, and further protected by a cap 23; A contact member 41 is provided on the side opposite to the melt, which accommodates a compensating conductor for transmitting an electrical signal and which can be inserted into the contact bush 52 of the measuring lancet. In the consumable plug-in unit of the immersion thermocouple, in which the parts emanating from both legs of the insulating tube of the thermocouple are connected to the compensating conductor, the respective leg end 2 of the insulating tube 21
A tubular bushing 31 made of a rubber elastic material is provided near the bushing 2, and the respective thermocouple conductors 12, 13 and the compensation conductor 14 are provided in the bushing internal hole 32 in parallel with the axis. Due to the repulsive force due to the elasticity of the bush 31, the thermocouple conductors 12 and 13 are moved to the compensation conductor 14.
A consumable plug-in unit for an immersion thermocouple, characterized in that it has a size that allows it to be pressed in contact with the immersion thermocouple. 2. A consumable plug-in unit for immersion thermocouples as claimed in claim 1, characterized in that the thermocouple conductors 12, 13 have a diameter equal to or smaller than 0.06 mm. 3. A consumable plug-in unit for an immersion thermocouple according to claim 1, characterized in that the compensation conductor 14 has a diameter equal to or smaller than 0.3 mm. 4. A consumable plug-in unit for an immersion thermocouple according to claim 3, characterized in that the compensation conductor 14 has a chamfered corner on the side on which it can be plugged into the bushing 31. 5 The bush internal hole 32 is connected to the step-shaped expansion part 3.
A consumable plug-in unit for an immersion thermocouple according to claim 1, characterized in that the expansion part 34 has a diameter equal to or smaller than the outer diameter of the insulating tube 21. . 6. Consumption of an immersion thermocouple according to claim 5, wherein the bush 31 is provided on each leg end 22 of the insulating tube 21 so as to cover the bottom surface of the extension part 34. Sex insertion unit. 7. Claims 1 and 6, characterized in that the opening of the bush 31 has a chamfer 35.
8. A consumable plug-in unit for an immersion thermocouple according to any one of paragraphs 1 and 7. 8 Each of the above-mentioned bushes 31 is connected to the contact member 4
8. A consumable plug-in unit for an immersion thermocouple according to claim 1, characterized in that the consumable plug-in unit for an immersion thermocouple is pluggably provided in the hole 42 on the side facing the melt of the immersion thermocouple. 9. A consumable plug-in unit for an immersion thermocouple according to claim 8, characterized in that the part of the contact member (41) facing towards the melt is arranged to be inserted into the molded member (24).