(54) METHOD AND APPARATUS FOR BONDING A CONNECTING RING TO A FLOW TUBE AND BALANCE BAR HAVING DIFFERENT THERMAL COEFFICIENTS OF EXPANSION IN A CORIOLIS FLOWMETER
(75) Inventor: Craig Brainerd Van Cleve, Lyons, CO (US)
(73) Assignee: Micro Motion, Inc., Boulder, CO (US)
( * ) Notice: Subject to any disclaimer, the term ol this patent is extended or adjusted under 35 U.S.C. 154(b) by 0 days.
(21) Appl. No.: 10/306,417
(22) Filed: Nov. 27, 2002
(65) Prior Publication Data
US 2003/0079554 Al May 1, 2003
Related U.S. Application Data
(62) Division of application No. 09/668,559, filed on Sep. 22, 2000, now Pat. No. 6,634,241.
(51) Int. CI. B23P 11/02
(52) U.S. CI 29/447; 29/458; 29/508;
29/516; 228/127; 228/132
(58) Field of Search 29/447, 458, 469,
29/508, 515, 516, 517; 73/861.354, 861.355, 861.356, 861.357; 285/381.1, 382.1; 228/127,
132
(56) References Cited
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FOREIGN PATENT DOCUMENTS
WO WO 00/47956 8/2000
* cited by examiner
Primary Examiner—Essama Omgba
(74) Attorney, Agent, or Firm—Dult Setter Ollila & Bornsen LLC
(57) ABSTRACT
A Coriolis flowmeter having a single flow tube surrounded by connecting rings and a balance bar whose ends are connected by the connecting rings to the flow tube. The balance bar has a thermal coefficient ol expansion greater than that ol the connecting rings and the flow tube. The outer circumlerential surface ol each connecting ring is tapered toward the axial center ol the flow tube. The inner circumlerential surface ol the balance bar has a taper matching that ol the connecting ring. The connecting ring can only be partially inserted into the space between the flow tube and the balance bar when the assembly is at room temperature. Braze material is then applied to the visible ends ol the surface common to the balance bar and the connecting rings as well as to the ends ol the surface common to the connecting rings and the flow tube. The structure is heated to brazing temperature to braze these common surfaces. The greater thermal coefficient ol expansion ol the balance bar enables the tapered connecting rings to be lully inserted into the space between the balance bar and the flow tube so that the outer ends ol the connecting rings are coplanar with the ends ol the balance bar. Another embodiment has a step on the inner surface ol the balance bar that limits the inward axial travel ol the connecting rings. Another embodiment has an annular ring between the flow tube and the connecting ring to reduce the peak stress.
15 Claims, 12 Drawing Sheets
