Spring-elastic measuring element comprising a flat connecting element that can be welded

Abstract

The invention relates to a spring-elastic measuring element ( 1 ) for thermometers, pressure switches or manometers consisting of an arc-shaped measuring tube ( 3 ), a base body ( 2 ) and a connecting element ( 10 ) for the measuring mechanism. The aim of the invention is to achieve the fully automated welding of the thermally influenced zone and to improve the latter. To achieve this, the connections between the measuring tube ( 3 ) and the base body ( 2 ) and the measuring tube and the connecting element ( 10 ) are obtained using connecting elements ( 11, 12 ) that can be welded. This allows the risk of contamination of the measuring system to be eliminated to a great extent and reduces the formation of corrosion and vibration cracks by the use of a small thermally influenced zone. A connecting element ( 11, 12 ) can also be produced as one-piece with the measuring tube ( 3 ) by expanding or creating a bead on the latter. The welded joint can be achieved by laser welding or electron-beam welding and the invention permits the welding of chrome-nickel steel to bronze.

Description

technical field [0001] The invention relates to a spring-type elastic measuring element, especially for thermometers, pressure switches or pressure gauges, comprising a curved or helical measuring tube, which is connected at one end to a base and at the other end to a measuring device The joint element connection is especially welded. Background technique [0002] For pressure- or temperature-sensitive measuring instruments, an elastic spring element made of thin-walled material can be used which deforms under the prevailing pressure. For this reason, the measuring element is generally formed in an arc shape and one end is connected to a solid base, and the other end is connected to the measuring device through a connecting rod, so that through the deformation that occurs, a small force is applied to the measuring device through the connecting rod. This thrust generated during the rotary movement is transmitted via the measuring device to the indicating device. In this cas...

AI Technical Summary

Problems solved by technology

Since the measuring springs of the different measuring ranges have different dimensions, large gaps cannot be avoided for this purpose, which prevents perfect gas-tight mechanical welding without wire supply

Furthermore, it should be emphasized that due to the high heat penetration for welding the measuring cell to the base body, the resulting oxide layer penetrates into the weld seam zone as far as the measuring system, wherein otherwise insignificant heat penetration results in structures in the heat-affected zone change, the strength and corrosion resistance of the spring-loaded elastic measuring cell are therefore adversely affected

Formation of blisters and cracks as well as material segregation are also observed in known welding methods, which lead to corrosion and nucleation of cracks

In addition, manual welding must be carried out. Due to the different material thicknesses, this work can only be carried out by experienced manual welding hands. For this reason, certain work experience must be used. Generally, other colleagues cannot be replaced immediately. Serious hindrance to welding work

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