Claims
- 1. A Coriolis flowmeter having:
a flow tube; connecting ring means having a center opening through which said flow tube extends; a tubular balance bar coaxial with said flow tube and surrounding an axial portion of said flow tube; said balance bar has a greater thermal coefficient of expansion than does said flow tube; axial end portions of said balance bar coaxial with and surrounding at least a portion of said connecting ring means; a radial inner circumferential surface of said connecting ring means coupled to an outer circumferential surface of said flow tube; a radial outer circumferential surface of said connecting ring means is tapered with a decreasing radius in a first direction with respect to the axial center of said flow tube; a radial inner circumferential surface of said end portions of said balance bar has a taper that matches said taper of said connecting ring means; said connecting ring means is adapted to be partially inserted into ends of said balance bar prior to a brazing operation and then fully inserted into said balance bar during said brazing operation as said balance bar expands in diameter more than said connecting ring; said tapered inner circumferential surface of said end portions of balance bar is adapted to be affixed by braze material to said tapered outer circumferential surface of said connecting ring means at the termination of said brazing operation.
- 2. The Coriolis flowmeter of claim 1 characterized in that said connecting ring means comprises:
a first connecting ring and a second connecting ring each adapted to be brazed to a different end of said balance bar; a tapered radial outer circumferential surface of said first connecting ring is adapted to be brazed to said tapered radial inner circumferential surface of a first end of said balance bar during said brazing; a tapered radial outer circumferential surface of said second connecting ring is adapted to be brazed to said tapered inner circumferential surface of a second end of said balance bar during said brazing operation.
- 3. The Coriolis flowmeter of claim 2 characterized in that said bond material is braze material.
- 4. The Coriolis flowmeter of claim 2 characterized in that said flow tube and said balance bar have different thermal coefficients of expansion.
- 5. The Coriolis flowmeter of claim 2 characterized in that said balance bar has a greater thermal coefficient of expansion than does said flow tube.
- 6. The Coriolis flowmeter of claim 2 characterized in that said first direction defines a taper that has a decreasing radius towards the axial center of said flow tube.
- 7. The Coriolis flowmeter of claim 2 characterized in that said first direction defines a taper that has an increasing radius towards the axial center of said flow tube.
- 8. The Coriolis flowmeter of claim 2 characterized in that said balance bar comprises a first and a second balance bar segments having axial inner end portions coupled to each other by spring means to accommodate a differential axial coefficient of expansion between said flow tube and said balance bar.
- 9. The Coriolis flowmeter of claim 2 characterized in that said balance bar comprises an integral elongated member.
- 10. The Coriolis flowmeter of claim 2 characterized in that said radial outer circumferential surface of said flow tube is affixed by braze material to said radial inner circumferential surfaces of said first and second connecting rings.
- 11. The Coriolis flowmeter of claim 10 in which said bond material comprises braze material.
- 12. The Coriolis flowmeter of claim 10 characterized in that said balance bar has a thermal coefficient of expansion greater than that of said first and second connecting rings and that said first and second connecting rings have a coefficient of expansion equal to that of said flow tube.
- 13. The Coriolis flowmeter of claim 10 further including a step on said radial inner end of said tapered circumferential surface of said balance bar that engages an axial inner end of said first and second connecting rings to limit the amount by which said first and second connecting rings can be axially inserted into said balance bar.
- 14. The Coriolis flowmeter Coriolis flowmeter of claim 2 further comprising:
first and second annular tube rings coaxial with and encircling axial portions of said flow tube; said axial portions of said radial outer circumferential surface of said flow tube are affixed by braze material to radial inner circumferential surfaces of said first and second annular tube rings; a radial outer circumferential surface of each of said first and second annular tube rings is tapered with an increasing radius towards said axial center of said flow tube; said radial inner circumferential surface of said first and second connecting rings has a taper that matches the taper of said first and second annular tube rings and has a diameter that decreases radially towards the axial center of said balance bar; said radial inner circumferential surface of said first and second connecting rings is adapted to be affixed by braze material to said radial outer circumferential surface of said first and second annular tube rings during said brazing operation.
- 15. The Coriolis flowmeter of claim 14 further including a step on said radial inner circumferential surface of said balance bar that engages the axial inner end of said first and second connecting rings to limit the amount by which said first and second connecting rings can be axially inserted into said balance bar during said brazing operation.
- 16. The Coriolis flowmeter of claim 14 characterized in that said balance bar has a thermal coefficient of expansion greater than that of said first and second connecting rings and that said first and second connecting rings have a thermal coefficient of expansion greater than that of said first and second annular tube rings and that of said flow tube.
- 17. The Coriolis flowmeter of claim 14 characterized in that said first and second connecting rings and said first and second annular tube rings and said balance bar have different thermal coefficients of expansion.
- 18. The Coriolis flowmeter of claim 14 characterized in that said bond material is braze material.
- 19. A method of assembling a Coriolis flowmeter having a flow tube, a connecting ring means, and a tubular balance bar, said method comprising the steps of:
extending said flow tube through a center opening in said tubular balance bar; positioning said flow tube so that said flow tube extends through a center opening of said connecting ring means and is coaxial with said balance bar; positioning said connecting ring means so that axial end portions of said balance bar are coaxial with and surround at least a portion of said connecting ring means; coupling an radial inner circumferential surface of said connecting ring means to said flow tube; a radial outer circumferential surface of said connecting ring means is tapered in a first direction with a decreasing radius with respect to the axial center of said flow tube; radial inner circumferential surfaces of said axial end portions of said balance bar have a taper that matches said taper of said connecting ring means; and said balance bar has a greater thermal coefficient of expansion than does said flow tube; brazing said tapered inner circumferential surface of said end portions of balance bar to said tapered outer circumferential surface of said connecting ring means, said connecting ring means being axially moved within said balance bar during said brazing beyond the axial location within said balance bar prior to brazing.
- 20. The method of claim 19 characterized in that said connecting ring means comprises a first connecting ring and a second connecting ring; said step of brazing comprises the step of moving each said connecting ring in an axial direction during said brazing operation so that the radial pressure exerted on said flow tube by each said connecting ring increases subsequent to brazing.
- 21. The method of claim 20 characterized in that said flow tube and said balance bar have different thermal coefficients of expansion and that said step of brazing comprises the steps of:
brazing said tapered inner circumferential surface of first and second end portions of balance bar to said tapered outer circumferential surfaces of said first and second connecting rings.
- 22. The method of claim 20 characterized in that said first direction defines a taper of said connecting ring having a decreasing radius towards the axial center of said flow tube.
- 23. The method of claim 20 characterized in that said step of brazing comprises the steps of:
axially moving said first and second connecting rings towards said axial center of said balance bar during said step of brazing; and cooling said brazed surfaces so that said greater thermal coefficient of expansion of said balance bar generates a radially compressive force against said first and second connecting rings and said flow tube.
- 24. The method of claim 21 characterized in that said step of coupling includes the step of bonding said outer circumferential surface of said flow tube to said inner circumferential surfaces of said first and second connecting rings.
- 25. The method of claim 24 in which said step of bonding includes the step of brazing.
- 26. The method of claim 20 characterized in that said step of bonding includes the step of brazing said outer circumferential surface of said flow tube to said inner circumferential surface of said first and second connecting rings; and
axially moving said first and second connecting rings towards said axial center of said balance bar during said step of brazing.
- 27. The method of claim 26 further including the step of forming a step on said inner tapered circumferential surface of said balance bar that engages axial inner ends of said first and second connecting rings to limit the amount by which said first and second connecting rings can be axially inserted into said balance bar during said brazing.
- 28. The method of claim 20 characterized in that:
first and second annular tube rings couple said flow tube with said first and second connecting rings; said method further includes the step of:
bonding said outer radial circumferential surface of said flow tube to an inner radial circumferential surface of each of said first and second annular tube rings; an outer radial circumferential surface of said first and second annular tube rings is tapered to have an axially increasing radius towards said axial center of said flow tube; said inner radial circumferential surface of said first and second connecting rings have a taper that matches that of said first and second annular tube rings and has a radius that decreases towards the axial mid portion of said balance bar; and brazing said tapered inner circumferential surface of said first and second connecting rings to said tapered outer circumferential surface of said first and second annular tube rings.
- 29. The method of claim 28 in which said step of axially moving said first and second connecting rings towards said axial center of said balance bar during said step of brazing.
- 30. The method of claim 29 further including the step of forming a step on said inner circumferential tapered surface of said balance bar that engages the axial inner end of said first and second connecting rings to limit the amount by which said first and second connecting rings can be axially inserted into said balance bar during said step of brazing.
- 31. The method of claim 28 characterized in that said balance bar has a thermal coefficient of expansion greater than that of said first and second connecting rings and that said first and second connecting rings have a thermal coefficient of expansion greater than that of said first and second annular tube rings and that of said flow tube;
said method further includes the step of axially moving said first and second connecting rings towards said axial center of said balance bar during said step of brazing.
- 32. The method of claim 28 characterized in that said first and second connecting rings and said first and second annular tube rings and said balance bar have different thermal coefficients of expansion and that said step of bonding includes the step of brazing;
said method further includes the step of axially moving said first and second connecting rings towards said axial center of said balance bar during said step of brazing.
- 33. The method of claim 28 further including the steps of:
orienting said flow tube and said balance bar so that a first end of said flow tube extends into a recess of a base; placing said first and second connecting rings concentric with said flow tube and axially at least partially within first and second ends of said balance bar so that the outer ends of said connecting rings extend axially beyond the ends of said balance bar; placing braze material proximate the axial end extremities of the junctions of surfaces common to said balance bar and said first and second connecting rings and junctions of surfaces common to said connecting rings and said flow tube; placing a mass on a second end of said flow tube so that said mass exerts a force on said connecting rings urging them axially into engagement with said balance bar; the outer ends of said connecting rings then extending axially beyond the ends of said balance bar; heating said balance bar and said connecting rings and said flow tube to brazing temperatures; the brazing temperature being effective to expand said balance bar radially to enable said connecting rings to move axially inward within said balance bar; and cooling said brazed surfaces so that said greater thermal coefficient of expansion of said balance bar generates a radially compressive force against said first and second connecting rings and said flow tube.
- 34. The method of claim 33 characterized in that said balance bar comprises first and a second axially separated segments and that said method further comprises the steps of connecting spring means between the axial inner end of each of said balance bar segments to accommodate a differential thermal coefficient of expansion between said flow tube and said balance bar segments.
- 35. The method of claim 20 characterized in that said first direction defines a taper of said connecting rings having an increasing radius towards the axial center of said flow tube.
- 36. The method of claim 35 further comprises the steps of:
axially moving said first and second end portions of said connecting rings towards said axial center of said balance bar during said step of brazing; brazing said tapered inner circumferential surfaces of said first and second end portions of balance bar with said tapered outer radial circumferential surfaces of first and second said connecting rings; and cooling said brazed surfaces so that said greater thermal coefficient of expansion of said balance bar generates a radially compressive force against said first and second connecting rings and said flow tube.
- 37. The method of claim 35 characterized in that said balance bar has a thermal coefficient of expansion greater than that of said first and second connecting rings and that said first and second connecting rings have a thermal coefficient of expansion greater than that of said flow tube and that said step of bonding includes the step of brazing;
said method further includes the step of axially moving said first and second end portions of said balance bar towards said axial center of said balance bar during said step of brazing.
- 38. The method of claim 35 characterized in that said balance bar comprises a pair of axially separated segments and that said method further includes the steps of:
extending a first end of said flow tube through a center opening of said first connecting ring; extending a second end of said flow tube through a center opening of a second connecting ring; affixing said first and second connecting rings to said flow tube; extending said first end of said flow tube and said first connecting ring through a first balance bar segment; extending said second end of said flow tube and said second connecting ring through a said second balance bar segment; placing braze material proximate the axial extremities said first and second connecting rings proximate said flow tube and said balance bar segments; exerting a force on said balance bar segments urging them towards an axial center of flow tube and said balance bar; heating said balance bar segments and said connecting rings and said flow tube to brazing temperatures; the brazing temperature being effective to expand said balance bar radially to enable said balance bar end segments to move axially inward toward said axial center of said flow tube and said balance bar; and, cooling said brazed surfaces so that said greater thermal coefficient of expansion of said balance bar segments generates a radially compressive force against said first and second connecting rings and said flow tube.
- 39. A method of assembling the Coriolis flowmeter of claim 1, said method comprising the steps of:
extending said flow tube through a center opening in said tubular balance bar; positioning said connecting ring means so that axial end portions of said balance bar are coaxial with and surround at least a portion of said connecting ring means; positioning said flow tube so that said flow tube extends through a center opening of said connecting ring means and is coaxial with said balance bar; positioning a radial inner circumferential surface of said connecting ring means against said flow tube; said outer radial circumferential surface of said connecting ring means is tapered in a first direction with a decreasing radius with respect to the axial center of said flow tube; said inner radial circumferential surfaces of said axial end portions of said balance bar have a taper that matches said taper of said connecting ring means; and brazing said tapered inner circumferential surface of said end portions of balance bar to said tapered outer circumferential surface of said connecting ring means; and moving said connecting ring in an axial direction during said brazing operation so that the radial pressure exerted on said flow tube by said connecting increases subsequent to brazing.
CROSS REFERENCE TO A RELATED APPLICATION
[0001] This application is a divisional of U.S. patent application Ser. No. 09/668,559 titled “Method and Apparatus for Bonding a Connecting Ring to a Flow Tube and Balance Bar of a Coriolis Flowmeter” and filed on Sep. 22, 2000. The referenced application is hereby incorporated by reference as if the referenced application were included in this application.
Divisions (1)
|
Number |
Date |
Country |
Parent |
09668559 |
Sep 2000 |
US |
Child |
10306417 |
Nov 2002 |
US |