US3903222A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Method for producing prestressed concrete
Assignee: Individual
•
Filing: 1974-04-11
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Granted: 1975-09-02
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Expires: 1994-04-11
Abstract
Abstract The invention consists of an improved method for producing prestressed concrete products wherein the improvement comprises the utilization of the concrete itself to provide the prestressing force which must be exerted on reinforcing wire strands used in the manufacture of said prestressed concrete products. The reinforcing wire is fed into and attached to the first mold in a train of molds and then through each of the following molds in series. The molds have fluent concrete inserted therein as they are guided along an endless track to a point at which the concrete has hardened and whence said molds move by force of gravity down an incline. The hardened concrete in the initial molds descends said incline at a computercontrolled rate whereby a calculated stress is imparted to the reinforcing wire strands in the subsequent molds containing fluent concrete. The calculations are based upon the force supplied by the weight of the descending molds containing hardened concrete and the rate at which said hardening occurs. The stress upon said reinforcing wire is gradually and evenly transferred from the wire to the concrete as the molds descend the incline whereupon, when the train of molds reaches a point at which the calculated stress is nulled, said reinforcing wire strands are severed at the point of entrance into said mold. A continuous production cycle may thereby be maintained with the subject invention whereby an economic advantage is obtained over prior art techniques.
Inventors
- 👤 Jr Patrick F Brown
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-05 10:52
CPC Classifications
B; B28; B28B; B28B23/00; B28B23/02; B28B23/04
Claims Analysis
Total Claims: 10
Claim 1
Independent Claim
217 words
AN IMPROVED METHOD FOR THE CONTINUOUS MANUFACTURE OF PRESTRESSED CONCRETE ARTICLES WHEREIN THE IMPROVEMENT COMPRISES THE SIMULTANEOUS AND PROGRESSIVE STEPS OF: A. CONTINOUSLY FEEDING REINFORCEMENT STRANDS THROUGH A BARKING MECHANISM TO THE FIRST MOLD IN A TRAIN OF MOVING MOLD FORMS, B. DISCHARGING FLUENT CONCRETE INTO SAID MOLD FORMS AS THE MOLDS ARE GUIDED ALONG A SUBSTANTIALLY LEVEL PORTION OF AN ENDLESS TRACK, SAID ENDLESS TRACK HAVING AN INCLINED PORTION INCLUDED THEREIN, C. MOVING SAID MOLD FORMS ALONG SAID SUBSTANTIALLY LEVEL PORTION OF SAID ENDLESS TRACK TO A POINT AT WHICH THE CONCRETE BECOMES HARD, D. ADVANCING SAID MOLD FORM CONTAINING SAID HARDENED CONCRETE ALONG SAID INCLINED PORTION EXCLUSIVELY BY FORCE OF GRAVITY WHEREBY SAID MOLD FORMS DESCEND SAID INCLINED PORTION THEREBY LOADING SAID REINFORCEMENT STRANDS TO PROVIDE THE REQUIRED STRESS, E. TRASMITTING A GRADUAL PRESTRESSING FORCE TO SAID HARDENED CONCRETE BY COMPUTER-CONTROLLED MEANS BY GRADUALLY REDUCING THE STRESSING LOAD ON SAID REINFORCEMENT STRANDS, F. CORRELATING THE SPEED OF SAID MOVING MOLD FORMS WITH THE TENSION ON SAID REINFORCEMENT STRANDE WHEREBY CONTROL IS MAINTAINED OF THE PRESTRESSING FORCE TRANSFERRED TO SAID CONCRETE ARTICLES, G. MAINTAINING CONSTANT SPACING BETWEEN SAID MOLD FORMS TO A POINT AT WHICH THE CONCRETE BECOMES HARD, AND H. GRADUALLY REDUCING THE PRESTRESSING FORCES ON THE STRANDS SUBSEQUENT TO THE HARDENING OF SAID CONCRETE.
Claim 2
Dependent Claim
217 words
AN IMPROVED METHOD FOR THE CONTINUOUS MANUFACTURE OF PRESTRESSED CONCRETE ARTICLES WHEREIN THE IMPROVEMENT COMPRISES THE SIMULTANEOUS AND PROGRESSIVE STEPS OF: A. CONTINOUSLY FEEDING REINFORCEMENT STRANDS THROUGH A BARKING MECHANISM TO THE FIRST MOLD IN A TRAIN OF MOVING MOLD FORMS, B. DISCHARGING FLUENT CONCRETE INTO SAID MOLD FORMS AS THE MOLDS ARE GUIDED ALONG A SUBSTANTIALLY LEVEL PORTION OF AN ENDLESS TRACK, SAID ENDLESS TRACK HAVING AN INCLINED PORTION INCLUDED THEREIN, C. MOVING SAID MOLD FORMS ALONG SAID SUBSTANTIALLY LEVEL PORTION OF SAID ENDLESS TRACK TO A POINT AT WHICH THE CONCRETE BECOMES HARD, D. ADVANCING SAID MOLD FORM CONTAINING SAID HARDENED CONCRETE ALONG SAID INCLINED PORTION EXCLUSIVELY BY FORCE OF GRAVITY WHEREBY SAID MOLD FORMS DESCEND SAID INCLINED PORTION THEREBY LOADING SAID REINFORCEMENT STRANDS TO PROVIDE THE REQUIRED STRESS, E. TRASMITTING A GRADUAL PRESTRESSING FORCE TO SAID HARDENED CONCRETE BY COMPUTER-CONTROLLED MEANS BY GRADUALLY REDUCING THE STRESSING LOAD ON SAID REINFORCEMENT STRANDS, F. CORRELATING THE SPEED OF SAID MOVING MOLD FORMS WITH THE TENSION ON SAID REINFORCEMENT STRANDE WHEREBY CONTROL IS MAINTAINED OF THE PRESTRESSING FORCE TRANSFERRED TO SAID CONCRETE ARTICLES, G. MAINTAINING CONSTANT SPACING BETWEEN SAID MOLD FORMS TO A POINT AT WHICH THE CONCRETE BECOMES HARD, AND H. GRADUALLY REDUCING THE PRESTRESSING FORCES ON THE STRANDS SUBSEQUENT TO THE HARDENING OF SAID CONCRETE.
Claim 3
Dependent Claim
48 words
An improved method for the continuous manufacture of prestressed concrete articles as recited in claim 1 wherein said graDual prestressing force comprises the force supplied by said mold forms having hardened concrete therein and wherein said mold forms advance along said inclined portion exclusively by force of gravity.
Claim 4
Dependent Claim
64 words
An improved method for the continuous manufacture of prestressed concrete articles as recited in claim 1 wherein said computer-controlled means for transmitting said prestressing force to said reinforcement strands comprises a computer programmed to convert tension-producing data created by the weight of said mold cars moving down said inclined portion into the braking action required to maintain a preset tension on said reinforcement strands.
Claim 5
Dependent Claim
43 words
An improved method for the continuous manufacture of prestressed concrete articles as recited in claim 1 wherein said gradual reduction of prestressing force is accomplished through the use of a series of brakes of retarders on said inclined portion of said endless track.
Claim 6
Dependent Claim
34 words
An improved method for the continuous manufacture of prestressed concrete articles as recited in claim 1 wherein said endless track having an inclined portion included therein utilizes the topography of hilly or mountainous terrain.
Claim 7
Dependent Claim
35 words
An improved method for the continuous manufacture of prestressed concrete articles as recited in claim 1 wherein said inclined portion of said endless track forms an angle of between 10* and 60* from the horizontal.
Claim 8
Dependent Claim
71 words
An improved method for the continuous manufacture of prestressed concrete articles as recited in claim 1 including utilizing wire supply means for continuously feeding reinforcement strands into said moving mold forms, attachment means for fastening wires to the first mold form in the series and braking means for providing tension upon the mold forms in series until said fluent concrete has hardened and said mold forms have reached said inclined portion.
Claim 9
Dependent Claim
60 words
An improved method for the continuous manufacture of prestressed concrete articles as recited in claim 1 wherein utilizing means for correlating the speed of said moving mold forms with the tension on said reinforcement strands comprises computerized utilization of tension-produced data and stress tables to automatically and simultaneously control braking mechanisms linked to said mold forms and said reinforcement strands.
Claim 10
Dependent Claim
49 words
An improved method for the continuous manufacture of prestressed concrete articles as recited in claim 8 wherein said computerized utilization of tension-produced data and stress tables to automatically and simultaneously control said braking mechanism comprises varying the degree of slope of the incline as performed by said retarding means.
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1978-09-01 | 1979-03-03 | 1979-09-02 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1982-09-01 | 1983-03-03 | 1983-09-02 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1986-09-01 | 1987-03-03 | 1987-09-02 | $7700.00 | Window Closed / Lapsed |