US4674971A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Concrete slab extruder with shear-action coring members
Assignee: Rakennusvalmiste Oy
•
Filing: 1985-09-09
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Granted: 1987-06-23
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Expires: 2005-09-09
Abstract
Abstract An extruder for the fabrication of concrete slabs, especially hollow-cored slabs, movable on a casting bed and incorporating a feed hopper or similar, at least one feeder, especially an auger, for generating internal pressure in the cast concrete, and at least one coring member or similar, for generating the desired slab cross-section. The extruder in accordance with the invention comprises an assembly of at least two wedged surfaces, of which at least one is fitted in conjunction with the coring member, and the space between the surfaces is continuously changing due to a cyclic longitudinal movement, generating inside the space a compacting shear action in the concrete mix.
Inventors
- 👤 Heikki I. Kankkunen
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-06 11:46
CPC Classifications
B; B28; B28B; B28B3/00; B28B3/20; B28B3/22; B28B3/228; B28B1/00; B28B1/08; B28B1/084
Claims Analysis
Total Claims: 9
Claim 1
Independent Claim
134 words
An extruder for casting concrete slabs, especially hollow-cored concrete slabs, moving on a casting bed, comprising: a feed hopper, at least two combinations of an auger and a coring member, each said combination having an axial direction and being positioned between mold plates, each said auger being located to receive concrete from said hopper, each said coring member having an annular groove which forms a wedge surface, adjacent said combinations having a space therebetween, means for cyclically reciprocating said combinations of an auger and a coring member in a parallel relationship in their axial direction such that adjacent combinations are moving in opposite directions at any given time, and said means causes said space between said combinations to continuously change in order to generate a compacting shear action in the concrete in said space.
Claim 2
Dependent Claim
134 words
An extruder for casting concrete slabs, especially hollow-cored concrete slabs, moving on a casting bed, comprising: a feed hopper, at least two combinations of an auger and a coring member, each said combination having an axial direction and being positioned between mold plates, each said auger being located to receive concrete from said hopper, each said coring member having an annular groove which forms a wedge surface, adjacent said combinations having a space therebetween, means for cyclically reciprocating said combinations of an auger and a coring member in a parallel relationship in their axial direction such that adjacent combinations are moving in opposite directions at any given time, and said means causes said space between said combinations to continuously change in order to generate a compacting shear action in the concrete in said space.
Claim 3
Dependent Claim
23 words
An extruder as claimed in claim 1, in which said means for cyclically reciprocating includes a guide bar connected to each said combination.
Claim 4
Dependent Claim
24 words
An extruder as claimed in claim 1, in which each said auger and said coring member are movable by said means as an entity.
Claim 5
Dependent Claim
19 words
An extruder as claimed in claim 1, in which said mold plates are each provided with a wedge surface.
Claim 6
Dependent Claim
25 words
An extruder as claimed in claim 1, in which said means for cyclically reciprocating is capable of providing a longitudinal movement by a push-pull action.
Claim 7
Dependent Claim
23 words
An extruder as claimed in claim 1, in which said wedge surfaces are formed on members which are positioned inside a flexible hose.
Claim 8
Dependent Claim
27 words
An extruder as claimed in claim 1, in which said coring member includes a portion having said wedge surfaces attached to the remainder of said coring member.
Claim 9
Dependent Claim
38 words
An extruder as claimed in claim 1, in which said means for cyclically reciprocating said combination is capable of producing longitudinal movement having an amplitude of 5 to 50 mm and a frequency of 1 to 10 Hz.
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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) | 1990-06-22 | 1990-12-22 | 1991-06-23 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1994-06-22 | 1994-12-22 | 1995-06-23 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1998-06-22 | 1998-12-22 | 1999-06-23 | $7700.00 | Window Closed / Lapsed |