US3837830A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Method for forming integral internal channels in glass tubing
Assignee: Individual
•
Filing: 1972-09-14
•
Granted: 1974-09-24
•
Expires: 1992-09-14
Abstract
Abstract A method for forming integral internal channels defined by a wall with an annular cross-section inside high softening temperature glass tubing is described. In particular, a reduced pressure is provided inside a rotating tube with heating outside which softens the glass for deformation by the reduced pressure while a smaller tube is maintained in position in contact with the inside walls of the larger tube. The pressure is the smaller tube is usually the same as that in the larger tube and is such that it can collapse at the point of contact to form at least one fusion band along the inside wall of the larger tube. The position of the smaller tube is maintained such that the larger tube has concave depressions between the fusion bands. Usually the heating is accomplished by a gas flame ring burner positioned under the larger tube and moved progressively along the larger tube until the desired fusion of the tubes is completed. The next step which is preferred is to provide a positive pressure in the larger tube with heating to soften the glass to move the concave depressions out and mold them against a platen provided in spaced relation to the depressions outside of the larger tube. This can also be progressively accomplished with the ring burner. While the glass tubes are being manipulated, the sections being fused and molded are maintained above the strain point temperature of the glass. The glass is then usually annealed and then it is cooled. The articles produced are strain free, compact, durable and particularly useful for heat transfer applications such as reflux, still-head and take-off condensers used in conducting chemical reactions and liquid distillation operations. Preferably the channels form a helical coil inside the tube. In addition an electrical resistance wire can be provided in the channels to produce reaction vessels suitable for heating liquids and for conducting chemical reactions.
Inventors
- 👤 W Eberhart
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-26 10:46
CPC Classifications
F; F16; F16L; F16L9/00; F16L9/10; F16L9/105; B; B01; B01L; B01L3/00; B01L3/56; B01L3/569; C; C03; C03B; C03B23/00; C03B23/04; C03B23/07; C03B23/073; C03B23/076; C03B23/20; C03B23/207; F16L9/18; F28; F28D; F28D1/00; F28D1/06; F28D7/00; F28D7/02; F28D7/024; F28F; F28F21/00; F28F21/006
Claims Analysis
Total Claims: 15
Claim 1
Independent Claim
305 words
The method for forming integral channels in glass tubing which comprises: a. providing at least one first circular round wall small diameter tube with a closed end and an open end the outer wall being adjacent to and enclosed by the inner walls of a second cylindrical tube; b. anchoring the smaller tube to the wall of the larger tube such that there is a line of glass to glass contact between the tubes; c. closing the ends of the larger tube with the smaller tube anchored inside such that the larger tube is rotatable along its axis and such that the open end of the smaller tube and the larger tube are connected to a common means for varying the pressure; d. rotating the larger tube with heating of the outside of the larger tube so that the points of contact of the smaller and larger tube walls are softened while providing a reduced pressure in the larger tube which produces essentially the same reduced pressure in the smaller tube permitting it to deform at the point of contact to form integral fusion bands with the inner walls of the larger tube with concave depressions between the fusion bands while maintaining the temperature of the fusion bands above the strain point during fusion; e. providing an elevated pressure within the larger tube while heating the outside walls of the larger tube with rotation to soften the glass while contacting the softened glass with a platen for molding the walls between the fusion bands while elevated pressure acts to move the depressed surfaces outward to conform to the platen and while maintaining the temperature above the strain point during molding; f. cooling the glass tubes with the fused bands to prevent cracking; and g. opening any glass sealed ends of at least the larger tube.
Claim 2
Independent Claim
305 words
The method for forming integral channels in glass tubing which comprises: a. providing at least one first circular round wall small diameter tube with a closed end and an open end the outer wall being adjacent to and enclosed by the inner walls of a second cylindrical tube; b. anchoring the smaller tube to the wall of the larger tube such that there is a line of glass to glass contact between the tubes; c. closing the ends of the larger tube with the smaller tube anchored inside such that the larger tube is rotatable along its axis and such that the open end of the smaller tube and the larger tube are connected to a common means for varying the pressure; d. rotating the larger tube with heating of the outside of the larger tube so that the points of contact of the smaller and larger tube walls are softened while providing a reduced pressure in the larger tube which produces essentially the same reduced pressure in the smaller tube permitting it to deform at the point of contact to form integral fusion bands with the inner walls of the larger tube with concave depressions between the fusion bands while maintaining the temperature of the fusion bands above the strain point during fusion; e. providing an elevated pressure within the larger tube while heating the outside walls of the larger tube with rotation to soften the glass while contacting the softened glass with a platen for molding the walls between the fusion bands while elevated pressure acts to move the depressed surfaces outward to conform to the platen and while maintaining the temperature above the strain point during molding; f. cooling the glass tubes with the fused bands to prevent cracking; and g. opening any glass sealed ends of at least the larger tube.
Claim 3
Dependent Claim
44 words
The method of claim 1 wherein the smaller tube provided in the larger tube is in the form of a helical coil, the coil outside diameter of which is such that it fits into the second larger tube in contact with the inner walls.
Claim 4
Dependent Claim
16 words
The method of claim 1 wherein the ends of the tubes are fitted with connector means.
Claim 5
Dependent Claim
26 words
The method of claim 1 wherein the heating is accomplished with natural gas and oxygen mixture flame in contact with the outside of the larger tube.
Claim 6
Dependent Claim
35 words
The method of claim 4 wherein the tubes are silica or borosilicate glass and the softening temperature of the glass is from between about 1245*C and 1260*C for borosilicate and 2500*C and 2700*C for silica.
Claim 7
Dependent Claim
36 words
The method of claim 1 wherein the tubes are borosilicate or silica glasses and are annealed at a temperature above about 500*C for borosilicate and about 900*C for silica at about 2* to 5*C per minute.
Claim 8
Dependent Claim
16 words
The method of claim 1 wherein the platen surface used for molding is composed of graphite.
Claim 9
Dependent Claim
44 words
The method of claim 1 wherein a length of the smaller tubing is provided along the axis of the larger tube as an extension of the smaller tube and which is held into place with a graphite rod during the formation of the channels.
Claim 10
Independent Claim
294 words
The method of formIng integral internal channels in glass tubing which comprises: a. providing at least one first small tube with a closed end and an opening the outer wall of which is anchored to the inner wall of a larger open ended second tube in a line of glass to glass contact; b. closing the ends of the larger tube such that the larger tube with the smaller tube anchored inside is rotatable along its length and such that the smaller tube and the larger tube are connected at the other end to means for varying the pressure inside the tubes; c. rotating the larger tube with heating of the outside wall of the larger tube so that the points of contact of the smaller and larger tubes are softened and while providing a reduced pressure in the larger tube and a pressure in the smaller tube permitting it to deform by partial collapse at the point of contact to form integral fusion bands and along the inner walls of the larger tube with concave cross-section depressions between the fusion bands while maintaining the temperature of the fusion bands above the strain point temperature during fusion; d. providing an elevated pressure within the larger tube with rotation along its length while heating the outside wall of the larger tube to soften the glass while contacting the softened glass with a platen for molding the walls between the fusion bands so that the elevated pressure acts to move the depressed surfaces outward to conform to the platen and while maintaining the temperature above the strain point during molding; e. cooling the tubes with the fused bands so as to prevent cracking; and f. opening any glass sealed ends of at least the larger tube.
Claim 11
Independent Claim
294 words
The method of formIng integral internal channels in glass tubing which comprises: a. providing at least one first small tube with a closed end and an opening the outer wall of which is anchored to the inner wall of a larger open ended second tube in a line of glass to glass contact; b. closing the ends of the larger tube such that the larger tube with the smaller tube anchored inside is rotatable along its length and such that the smaller tube and the larger tube are connected at the other end to means for varying the pressure inside the tubes; c. rotating the larger tube with heating of the outside wall of the larger tube so that the points of contact of the smaller and larger tubes are softened and while providing a reduced pressure in the larger tube and a pressure in the smaller tube permitting it to deform by partial collapse at the point of contact to form integral fusion bands and along the inner walls of the larger tube with concave cross-section depressions between the fusion bands while maintaining the temperature of the fusion bands above the strain point temperature during fusion; d. providing an elevated pressure within the larger tube with rotation along its length while heating the outside wall of the larger tube to soften the glass while contacting the softened glass with a platen for molding the walls between the fusion bands so that the elevated pressure acts to move the depressed surfaces outward to conform to the platen and while maintaining the temperature above the strain point during molding; e. cooling the tubes with the fused bands so as to prevent cracking; and f. opening any glass sealed ends of at least the larger tube.
Claim 12
Dependent Claim
22 words
The method of claim 9 wherein the closed end of the smaller tube is opened through the wall of the larger tube.
Claim 13
Dependent Claim
23 words
The method of claim 9 wherein the rate of rotation of the larger tube is between about 10 and 50 revolutions per minute.
Claim 14
Independent Claim
70 words
The method of fusing glass tubes together which comprises: a. contacting an outer wall of a small tube with an inside wall of a large tube; b. providing a reduced pressure inside the tubes while heating so as to fuse tubes together in a band; and c. providing an elevated pressure within the heated fused tubes sufficient to expand the larger tube into shaping contact with an outside forming surface.
Claim 15
Independent Claim
70 words
The method of fusing glass tubes together which comprises: a. contacting an outer wall of a small tube with an inside wall of a large tube; b. providing a reduced pressure inside the tubes while heating so as to fuse tubes together in a band; and c. providing an elevated pressure within the heated fused tubes sufficient to expand the larger tube into shaping contact with an outside forming surface.
References Cited (Backward Citations)
US1926552A
Cited
US3696003A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1977-09-23 | 1978-03-25 | 1978-09-24 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1981-09-23 | 1982-03-25 | 1982-09-24 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1985-09-23 | 1986-03-25 | 1986-09-24 | $7700.00 | Window Closed / Lapsed |