SU1767597A1 - Device for thermocouple cable splicing - Google Patents

Abstract

Use: electrical engineering, cable technology in the manufacture of thermocouples with a metal sheath and mineral insulation. The essence of the invention: a device containing an ultrasonic oscillation source 1 with a waveguide 2 and a cable clamping unit 3 is provided with a limiter of bending vibrations of the working end of the cable. Limiter 4 is mounted coaxially with the clamping unit 3 and, like the latter, has the possibility of movement along the cable feed direction. A source 1 with a waveguide 2 is placed between the clamping unit 3 and the limiter 4. The invention aims at improving the quality of cable cutting by ensuring the removal of the powder material of the insulating layer without damaging the outer cable jacket. 1 il.

Description

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The invention relates to cable technology and can be used in the manufacture of thermocouples from thermocouple cable with a metal sheath and mineral insulation.

A device for preparing for welding the working ends of a thermocouple cable (1) is known, which includes means for fastening and a mechanism for breaking mineral insulation. . In this device, the cable blank is fastened in an upright position and the mineral insulation (magnesia) is drilled together with the -Rimo-conductor to the required depth. The depth depends on the diameter of the cable and is recommended to be 3.5 mm for a diameter of 1.0-1.5 mm. The diameter of the drill should be 0.1 mm smaller than the internal diameter of the cable sheath in order not to damage the shell walls. Then, using a drill and medical burs, the insulation around the thermoelectrode strands is removed to a depth depending on the cable diameter. Thus, for a cable with a diameter of 1.0-1.5 mm, the insulation is removed to a depth of about 0.5-1.5 mm. This is the minimum depth that allows thermoelectrode strands to be brought together before they come into contact with each other before welding.

The drawback of the device is the low productivity of cutting the working end of the thermocouple cable, especially when cutting the cable with a diameter of less than 3 mm, a high rejection rate, due to damage to the internal cores in the process of their release from mineral insulation. A cable with a diameter of less than 1.5-2.0 mm is practically impossible to prepare for welding in a known manner, and therefore produce a high-quality thermocouple.

A device for cutting mineral insulated cable (2) is known, which includes a source of ultrasonic vibrations, a waveguide, a reflector. By making an annular notch on the cable sheath and exciting ultrasonic vibrations in it, the sheath is destroyed, and then the insulation is loosened as a result of vibrations of the cores. Such a device is used to cut long cable ends when connected to measuring instruments.

A disadvantage of the known device is the impossibility of its use for cutting the working end of a thermocouple cable for welding, since the sheath is destroyed during the cutting process, and the insulating powder is also loosened. To cut the same working end of the thermocouple cable for welding, the sheath and cores should

to be intact, and the discharge of powder should occur in a small area.

The aim of the invention is to improve the quality of cutting by providing

removing the powder material of the insulating layer without damaging the cable outer sheath.

The goal is achieved by the fact that a device for cutting a thermocouple cable, including a source of ultrasonic vibrations with a waveguide, a clamping unit mounted for movement along the cable feed direction, is additionally equipped with a bending vibration limiter,

which is mounted coaxially with the clamping unit and has the ability to move along the cable feed direction, and the source of ultrasonic vibrations with the waveguide is placed between the clamping unit and

limiter.

The drawing shows the proposed device.

The device contains a source of 1 ultrasonic vibrations with a waveguide 2, node 3

cable clamp, mounted for movement along the cable feed direction, limiter 4 bending vibrations of the working end of a dog, which is mounted coaxially with the clamp assembly 3 and has

possibility of movement along the cable feed direction. The ultrasonic oscillation source 1 with waveguide 2 is placed between the clamping unit 3 and the stopper 4. The gap, in which the thermocouple cable is located in the clamping unit 3, is adjusted with screws 5 and 6, which allows cutting the working ends of cables of different diameters.

The device works as follows.

The cutting end of the thermocouple cable 7 is fixed at the end of the waveguide 2 and, turning on the ultrasonic oscillation source 1, excites bending oscillations in it with a minimum output power. By varying the frequency of the source of ultrasonic vibrations, the maximum amplitude of the bending vibrations in the cable in the region from the waveguide is dB

2 to limiter 4. By moving the clamping unit 3 of the cable 7 and fixing the working end of the cable in it with the help of the screw 5, it is ensured that the bending vibrations do not spread in it. This excludes destruction.

lived in the cable at the nodal points of bending vibrations.

Then the limiter 4 is moved so that the end of the cable to be cut is located in its gap, Increasing the power of the ultrasonic generator and setting the gap with the screw 6, at which the discharge rate of the powder is maximum, cut the cable to the required depth. Due to the collisions of the end of the cable 7 with the limiter 4, the discharge of the insulating powder occurs almost instantaneously without destroying the metal sheath and the wires, and with decreasing cable diameter, the cutting time of the working end of the thermocouple cable for welding is reduced.

An example of a specific implementation of the method.

On this device, working ends of thermocouple cable KTMS (XA) of various diameters from 1.5 to 0.2 mm were prepared for welding. UZDN-1M generator with a 22 kHz magnetostrictive transducer was used as a source of ultrasonic vibrations. The amplitude of the flexural ultrasonic vibrations was, depending on the cable diameter, from 4 to 25 microns, and by adjusting the power of the ultrasonic generator, the amplitude of the flexural vibrations of the cable was varied from zero to the maximum value.

Instead of a pipe, any bending vibration limiter can be used, for example, an ordinary clamp.

The preparation time of the thermocouple cable KTMS (HA) with a diameter of 1.5 mm for welding the working spa according to the known technology was 30 minutes. The use of ultrasonic powder discharge made it possible to reduce the time to 40 seconds. In preparation for the welding of thermocouple cores of a cable with a diameter of 1.0 mm, the time was 45 minutes and 1 minute, respectively, and due to the damage to the cores in the first case, 10 cm of cable was spent in a marriage. Cable

with a diameter of less than 1.0 mm, the available mechanical tools could not be freed from mineral insulation. The same powder is discharged using

ultrasonic vibrations could be implemented for a cable with a diameter of 0.2 mm and a high-quality thermocouple with non-insulated junction (junction closed to the shell) was manufactured. The time of discharge was 1.5

min The amplitude of the displacements was equal to 25 μm.

The use of the proposed device allows cable stripping of almost any small diameter and obtaining

high-quality thermocouples, which expands the technological capabilities of the device by producing thermocouples of small diameter. Thus, using the proposed device, thermocouples with a diameter of

0.5 mm, which is impossible to implement by known methods.

Claims (1)

The invention The device for cutting thermocouple a cable comprising a source of ultrasonic vibrations with a waveguide and a cable clamping unit mounted for movement along the cable feed direction, characterized in that improving the quality of cutting by ensuring the removal of the powder material of the insulating layer without damaging the outer sheath of the cable, the device is equipped with a bending vibration limiter the working end of the cable, which is installed coaxially with the clamping unit and has the ability to move along the cable feed direction, and the source of ultrasonic vibrations with the waveguide is placed between clamping unit and limiter.