Tilt-up construction chamfers

Information

  • Patent Grant
  • 6702247
  • Patent Number
    6,702,247
  • Date Filed
    Tuesday, July 31, 2001
    23 years ago
  • Date Issued
    Tuesday, March 9, 2004
    20 years ago
Abstract
A chamfer for forming precast concrete wall panels used in tilt-up construction. The chamfer includes an elongate base portion and at least one chamfer portion coextensive with the lengthwise direction of the elongate base portion. The base portion defines a substantially horizontal base plane. The chamfer portion includes a first leg disposed upstanding relative to the base portion, and a second leg portion angularly disposed relative the first leg. The second leg further includes at least one flexible edge that projects beyond at least the base plane or the plane defined by the lengthwise direction extension of the first leg. Depending on which part of the second leg the edge is cantilevered from, it forms a sealed relationship between the chamfer and a casting surface, the chamfer and a plank used as part of the wall form, or both. The application of weight, usually due to the addition of a plank, causes the base portion of the chamfer to experience beam-like flexure, which in turn causes the flexible edges disposed on the chamfer outside the elastic curve defined by the flexed base portion to splay, and edges disposed on the chamfer inside the elastic curve to pinch, thereby effecting a seal to minimize or eliminate leakage associated with the poured concrete.
Description




BACKGROUND OF THE INVENTION




Tilt-up (or precast) construction of concrete wall sections is well-known in the art. In such an approach, forms are placed edgewise on a flat casting surface, and filled with concrete, which is then cured. Once the concrete has set, the form is removed and the wall is tilted up into the preferred, typically vertical, orientation. Most forms are made of conventional wood planks, such as two-by-eights and the like. To keep the wood from shifting during the form assembly portion of the operation, as well as to provide smooth, beveled edges to the finished concrete slab, single or double chamfers have been employed. These chamfers are often in the shape of a triangle with an extended base for plank edge support (in the case of the single chamfer variant), or a trapezoidal member with a plank-engaging channel disposed in the center (the dual chamfer variant). When placed in the chamfer, the vertically extending widthwise dimension of the plank defines the thickness of the concrete wall panel to be poured. The chamfer is placed to engage every plank that makes up the form.




One problem associated with conventional chamfer construction is the tendency of the poured concrete to leak into gaps prior to drying and hardening. This problem is especially acute between the chamfer and the casting surface, and between the chamfer and the plank, as the resulting dried portion that has leaked through can stick to the chamfer, which can in turn lead to an unintended, cost-prohibitive one-time chamfer use. In addition, if the dried concrete that has leaked through bonds to the finished product wall section and subsequently breaks off during handling, the bond might be strong enough to take portions of the finished product with it, thus adversely effecting the quality of the finished product. Prior art attempts at providing a seal to preclude the occurrence of leaking have been of a passive nature in that the chamfer relies on a close fit to accept a plank of standard thickness without gaps, but does nothing to actively close plank-to-chamfer gaps. In addition, no attempts have been made to provide seals between the chamfer and the casting surface.




Accordingly, there exists a need for a device that can ensure that tilt-up wall panels are precast with a minimum amount of poured concrete bleed-through, thereby avoiding frame-chamfer bonding and subsequent difficulty in separating the two.




SUMMARY OF THE INVENTION




The need is met by the present invention, which comprises a sealing chamfer used to support tilt-up wall panels without the disadvantages of the prior art. According to a first aspect of the present invention, a chamfer for engaging a plank to form concrete wall panels for tilt-up construction is disclosed. The chamfer, which includes a base portion, at least one chamfer portion, and a plank-accepting portion defined by adjacent cooperation of the base and chamfer portions, is configured for substantially horizontal placement upon a casting surface, such as a smooth floor. As such, it can accept a form, preferably made of individual wood planks secured together, which can be coupled to the chamfer to produce a mold capable of accepting poured concrete. The base portion defines a base plane, and is elongate along a lengthwise direction and terminates in a pair of lateral edges that project along a widthwise direction. Both the upper and lower surfaces of the base portion are substantially flat. Each chamfer portion is disposed along one of the pair of lateral edges of the base portion and is substantially coextensive therewith along the base portion's lengthwise direction. Each chamfer portion defines a generally triangular shaped structure (when viewed end-on) made up of a normal leg disposed normal to the base portion to define a normal leg plane and an angular leg angularly disposed relative the normal leg. The angular leg additionally defines at least one flexible edge that projects beyond at least one of the base plane or the normal leg plane. As a result, when the chamfer includes a flexible edge that projects beyond the base plane, and is placed on a substantially flat casting surface, the substantially flat lower surface of the chamfer's base portion does not contact the casting surface. The gap formed by this configuration permits a certain amount of flexure in the chamfer when a load is applied. This flexure allows these cantilevered flexible edges of the chamfer portion to move in response to the base portion such that when the base portion flexes under a load (such as the placement of a plank in the plank-accepting portion), the fit between the flexible edges and an abutting surface, such as a plank or casting surface, is enhanced, thereby minimizing or eliminating the leakage of the poured concrete to areas outside the preconfigured mold volume. As used in conjunction with the present disclosure, the term “substantially” refers to an arrangement of elements or features that, while in theory would be expected to exhibit exact correspondence or behavior, may, in practice embody something slightly less than exact. For example, in the present context, even if the chamfer portion is cut short near the ends of the chamfer to facilitate the right-angled joining of two or more chamfers, the extension of the chamfer portion is still “substantially coextensive” with the elongate base portion under the present definition. By way of another example, a portion need not project perpendicularly out of a horizontal plane to be considered “substantially upstanding” as long as it points in a generally upward direction.




Optionally, a pair of flexible edges can be configured to extend from each angular leg such that one of the flexible edges projects beyond the base plane, while the other projects beyond the normal leg plane. An additional option includes having the one or more flexible edges be cooperative with the base portion such that, upon application of a load to the base portion, the base portion flexes to effect a sealed relationship between the one or more flexible edges and the casting surface, plank or both. The one or more chamfer portions may further comprise a cantilever leg that extends angularly from the angular leg and is disposed coplanar with the base portion. Moreover, the chamfer can be made of plastic, such as polyvinyl chloride (PVC). The use of such materials is beneficial in that, in addition to being inexpensive to produce (such as by extrusion, where long, continuous pieces can be made and cut to desired lengths), they are fracture-resistant as well as relatively non-stick, so that what little dried concrete residue remains after each use can be easily removed, thus prolonging the useful life of the chamfer. By virtue of the continuous-production nature of PVC and related materials, the chamfer and base portions can optionally comprise one piece, thus obviating separate joining steps.




According to another aspect of the invention, a chamfer includes a base portion and a pair of chamfer portions disposed along the base portion's widthwise lateral edges. The dual chamfer configuration is similar to that of the previous embodiment, with the exception that both widthwise edges of the base portion have a chamfer portion disposed along them. Accordingly, the plank-accepting portion is now defined by a channel, formed on the bottom by the base portion, and on the sides by the opposed upstanding normal legs of the chamfer portion pair. As before, the chamfer portion extends substantially the entire length of the base portion's elongate dimension. The lower surface of the base portion is configured to not engage with the casting surface until an application of a load on the chamfer. As with the previous embodiment, in one option, the at least one flexible edge can be a pair of flexible edges configured to extend from each angular leg such that one of the flexible edges projects beyond the base plane, while the other projects beyond the normal leg plane. An additional option includes having the one or more flexible edges be cooperative with the base portion such that, upon application of a load to the base portion, the base portion flexes to effect a sealed relationship between the one or more flexible edges and the casting surface, plank or both.




According to another aspect of the present invention, a method of forming a precast wall panel for tilt-up construction is disclosed. The method utilizes one or more chamfers that are configurationally similar to that of the previous embodiments, in that each chamfer is made up of a base portion and a chamfer portion which together define a plank-accepting portion, and may be either of the single or double chamfer variants, as previously discussed. The chamfer portion itself is made up of at least a normal leg and an angular leg, and the angular leg further includes at least one projecting flexible edge. The method includes placing one or more chamfers on a casting surface, arranging the one or more chamfers to accept a form, placing the form into the plank-accepting portion of the one or more chamfers, pouring concrete into a mold defined by the chamfer and the form; and curing the concrete. The configuration of the chamfer of the present invention is such that the weight of the planks in the form causes any projecting flexible edge on the outer part of the chamfer radius of curvature to splay, and any projecting flexible edge on the inner part of the chamfer radius of curvature to pinch, thereby effecting a tight fit between adjacent surfaces of the chamfer, casting surface and plank to prevent or minimize poured concrete leakage. Optionally, an additional step to the method may include securing the chamfer to the casting surface. This may be accomplished in any number of conventional joining or fastening techniques.











BRIEF DESCRIPTION OF THE DRAWINGS





FIG. 1A

is a perspective view of a double chamfer according to an embodiment of the present invention;





FIG. 1B

is an end view of a double chamfer according to an embodiment of the present invention;





FIG. 2A

is a perspective view of a single chamfer according to an embodiment of the present invention;





FIG. 2B

is an end view of a single chamfer according to an embodiment of the present invention;





FIG. 3

is a perspective view of the double chamfer of

FIG. 1A

with a wooden plank disposed therein;





FIG. 4

is an end view of the double chamfer with plank of

FIG. 3

, showing the tendency of the outer radius of curvature flexible edges to splay and the inner radius of curvature flexible edges to pinch under a load; and





FIG. 5

is a perspective view showing the formation of a precast panel using the chamfer and plank of FIG.


3


.











DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS




Referring first to

FIGS. 1A and 1B

, a chamfer


10


including a base portion


20


and a chamfer portion


30


is shown. The base portion


20


defines as a base plane the plane that extends in a generally horizontal fashion from the edges of the base portion along lines defined by the base portion's top and bottom surfaces


20


A and


20


B, respectively. The generally triangular-shaped chamfer portion


30


is disposed along one of two lateral edges


25


A,


25


B of base portion


20


, and is substantially coextensive with the elongate lengthwise dimension L of the base portion


20


. As shown particularly in

FIG. 1B

, the chamfer portion


30


extends from lateral edge


25


B, and includes a normal leg


33


, an angular leg


35


and an optional cantilever leg


37


. The base portion


20


and chamfer portion


30


cooperate to define a plank-accepting portion


40


. In its preferred orientation, chamfer


10


rests substantially horizontally on a casting surface


50


, which is preferably a smooth floor or similar tilt-up wall assembly space. Angular leg


35


is further defined by one or more flexible edges


35


A,


35


B. The flexible edge


35


A projects beyond the base plane defined by the base portion


20


so that, when chamfer


10


is placed on casting surface


50


, the only contact between them occurs at the lateral ends, as a gap


60


is formed between the substantially flat lower surface


20


B and casting surface


50


. Likewise, flexible edge


35


B projects beyond the normal plane defined by normal leg


33


such that a plank (not shown in

FIGS. 1A and 1B

) inserted into plank-accepting portion


40


contacts chamfer portion


30


predominantly at the tip of flexible edge


35


B.




Referring now to

FIGS. 2A and 2B

, a chamfer


110


including a base portion


120


, chamfer pair portion


130


, and a plank-accepting portion, defined by channel


140


, formed between the chamfer pair portions


130


A,


130


B and the upper surface


120


A of base portion


120


, is shown. Each of the generally triangular-shaped chamfer pair portions


130


A,


130


B are disposed along a lengthwise edge


125


A,


125


B of the base portion


120


. The width of the channel


140


is such that a plank can fit snugly therein when placed in edgewise. As with the previous embodiment, the chamfer


110


construction is such that flexible edges


135


A,


135


B project from one or both ends of the angular leg


135


so that when the chamfer


110


is placed on a generally flat surface, such as a casting surface


150


, a gap


160


is formed such that the lower surface


120


B of base portion


120


does not contact the casting surface


150


until a downward-acting load (such as due to the weight of an inserted plank, discussed in more detail below) causes the chamfer


110


to flex. A groove


170


, centrally-disposed in the upper surface


120


A of base portion


120


may optionally be added to promote flexure of the chamfer


110


.




As clearly shown in

FIG. 2B

, each projecting flexible edge


135


A defines at its terminus a discrete contact surface that engages the casting surface


150


. The discrete contact surface illustrated in

FIG. 2B

is a result of the relatively small total surface area at the terminus of the flexible edge


135


A. As is also clearly shown in

FIG. 2B

, the casting surface


150


and discrete contact surfaces defined by the flexible edges of each chamfer portion


130


A,


130


B lie in a common plane which may be referred to as the casting surface contact plane. Respective discrete contact surfaces are also defined by each projecting flexible edge


135


B. Likewise, the single chamfer variant shown in

FIGS. 1A and 1B

highlights the discrete contact surface of the projecting flexible edges


35


A,


35


B. In both variants, there exists a reduced contact area between the chamfer and the casting surface.




Referring now to

FIGS. 3 and 4

, a plank


200


is shown inserted into channel


140


of the chamfer of FIG.


2


. As shown in particularly in

FIG. 3

, the chamfer is sized such that a close fit


300


between the plank and the chamfer


110


is ensured. By being sized to fit closely with the dimensions of plank


200


, the amount of flexure that chamfer


110


needs to go through is kept to a minimum, so that dimensional tolerances of the form and resulting cast wall remain tight. Turning particularly now to

FIG. 4

, the flexure of a dual chamfer


110


according to one of the previous aspects of the present invention is shown. When a load is applied (shown in the figure as due to the weight of plank


200


), a downward-acting force


400


causes the base portion


120


, which under a nonloaded condition does not contact casting surface


150


, to flex. In this loading scenario, the chamfer


110


acts like a beam, and includes a radius of curvature corresponding to the magnitude of the force


400


and the constraints placed on chamfer flexure by the casting surface


150


. Neutral bending plane (also known as the elastic curve) EE defines the radius of curvature in that the radius of curvature along any point on the elastic curve EE is equal to the radius of a circle with a circumference that conforms to the elastic curve's shape at that point. Under the bending caused by force


400


, a moment M is set up in the two chamfers


110


, which causes the flexible edges


135


B disposed on the inner part of the radius of curvature (i.e.: those disposed inward of the elastic curve EE) to crowd inward, thus producing a pinching effect on any surface they come in contact with, which, in the present invention is preferably surfaces


200


A,


200


B of plank


200


. Likewise, the flexible edges


135


A disposed on the outer part of the radius of curvature (i.e.: those disposed outside of elastic curve EE) tend to splay, thus producing a tighter frictional fit on the casting surface


150


. The combined effect of the flexible edges is to produce a tighter frictional fit between the chamfer


110


and the casting surface


150


(in the case of flexible edges


135


A), and between the chamfer


110


and the plank


200


(in the case of flexible edges


135


B), thus reducing the likelihood of unwanted concrete buildup beyond the boundaries of the desired tilt-up wall shape.




Referring next to

FIG. 5

in conjunction with

FIGS. 3 and 4

, the preparation of a precast panel using a chamfer


110


according to an embodiment of the present invention is shown. Chamfer


110


is first placed on casting surface


150


. As previously discussed, chamfer


110


can be secured to casting surface


150


by any suitable means. Next, plank


200


is placed within channel


140


of chamfer


110


at places along locations where a chamfered finish is desired. The weight of plank


200


causes chamfer


110


to flex. This in turn causes flexible edges


135


A,


135


B to move relative the casting surface


150


and plank


200


, respectively, thereby forming seals to inhibit the flow of concrete (or other pourable, castable material) in between the plank


200


, chamfer


110


and casting surface


150


. Thereafter, the concrete can be poured into a mold formed by the planks


200


and chamfers


110


, and allowed to cure.




Having described the invention in detail and by reference to preferred embodiments thereof, it will be apparent that modifications and variations are possible without departing from the scope of the invention which is defined in the appended claims.



Claims
  • 1. A chamfer for forming one or more precast panels on a casting surface, said chamfer comprising:a base portion comprising an upper surface and a lower surface such that a base plane is defined along said lower surface, said base portion elongate along a lengthwise direction and including a pair of lateral edges that project along a widthwise direction; and a pair of chamfer portions, each coupled to one of said pair of lateral edges of said base portion such that together said base portion and said chamfer portions define a unitary construction, each of said pair of chamfer portions substantially coextensive with said base portion along said lengthwise direction, each of said pair of chamfer portions comprising: a chamfer surface angularly coupled to said base portion; a first projecting edge disposed at a lower end of said chamfer portion and projecting beyond said base plane, said first projecting edge defining a discrete contact surface for engaging said casting surface such that absent the application of a load to said base portion, a gap is defined between said base plane and a casting surface contact plane upon which said first projecting edge is configured to rest, and further such that, upon application of a load to said base portion of said chamfer, said base portion flexes to splay said first projecting edge, thereby effecting a sealed relationship between said first projecting edge and said casting surface; and a second projecting edge disposed at an upper end of said chamfer portion, said second projecting edge defining a discrete contact surface for engaging a plank to be disposed between said pair of chamfer portions, said second projecting edge configured such that absent the application of a load to said base portion of said chamfer, said second projecting edge can slidably accept said plank, and further such that upon application of a load to said base poriton, said base portion flexes to force said second projecting edges against said plank to form a sealed relationship therebetween.
  • 2. A chamfer as claimed in claim 1 wherein each of said pair of chamfer portions comprises an upstanding leg, an angular leg, and a cantilever leg.
  • 3. A chamfer as claimed in claim 2 wherein said chamfer surface is defined by said angular leg.
  • 4. A chamfer as claimed in claim 2 wherein said cantilever leg is disposed coplanar with said base portion and extends angularly from said angular leg.
  • 5. A chamfer as claimed in claim 2 wherein said angular leg is coupled to yet distinct from said upstanding leg, and said cantilever leg is coupled to yet distinct from said angular leg.
  • 6. A chamfer as claimed in claim 1 wherein each of said chamfer portions are coupled to one of said pair of lateral edges of said base portion through a substantially upstanding leg extending from said base portion.
  • 7. A chamfer as claimed in claim 1 wherein:each of said chamfer portions are coupled to one of said pair of lateral edges of said base portion through a substantially upstanding leg extending from said base portion; said upstanding leg defines an upstanding leg plane; and said second projecting edge intersects with and projects beyond said upstanding leg plane.
  • 8. A chamfer as claimed in claim 1 wherein said chamfer is made of plastic.
  • 9. A chamfer as claimed in claim 1 wherein said chamfer comprises an extruded plastic piece.
  • 10. A chamfer as claimed in claim 1 wherein said base portion further comprises a groove disposed in said upper surface of said base portion.
  • 11. A plank and chamfer assembly for forming one or more precast panels on a casting surface, said assembly comprising:a chamfer comprising: a base portion comprising an upper surface and a lower surface such that a base plane is defined along said lower surface, said base portion elongate along a lengthwise direction and including a pair of lateral edges that project along a widthwise direction; a pair of substantially upstanding legs, each extending substantially perpendicular to said base plane to define an upstanding leg plane; and a pair of chamfer portions, each coupled to one of said pair of lateral edges of said base portion such that together said base portion, said substantially upstanding leg and said chamfer portions define a unitary construction, each of said pair of chamfer portions substantially coextensive with said base portion along said lengthwise direction, each of said pair of chamfer portions comprising: a chamfer surface angularly coupled to said base portion; a first projecting edge disposed at a lower end of said chamfer portion and projecting beyond said base plane, said first projecting edge defining a discrete contact surface for engaging said casting surface such that a gap is defined between said base plane and a casting surface contact plane upon which said first projecting edge is configured to rest; and a second projecting edge disposed at an upper end of said chamfer portion and projecting beyond said leg plane, said second projecting edge defining a discrete contact surface for engaging said plank; and a plank configured to be disposed in said chamfer such that upon placement of said plank into said chamfer, said first and second projecting edges form a seal with said plank.
  • 12. A method of forming a precast panel, said method comprising:placing at least one chamfer on a casting surface, said chamfer comprising: a base portion comprising an upper surface and a lower surface such that a base plane is defined along said lower surface, said base portion elongate along a lengthwise direction and including a pair of lateral edges that project along a widthwise direction; a pair of substantially upstanding legs, each extending substantially perpendicular to said base plane to define an upstanding leg plane; and a pair of chamfer portions, each coupled to one of said pair of lateral edges of said base portion such that together said base portion, said substantially upstanding leg and said chamfer portions define a unitary construction, each of said pair of chamfer portions substantially coextensive with said base portion along said lengthwise direction, each of said pair of chamfer portions comprising: a chamfer surface angularly coupled to said base portion; a first projecting edge disposed at a lower end of said chamfer portion and projecting beyond said base plane, said first projecting edge defining a discrete contact surface for engaging said casting surface such that a gap is defined between said base plane and a casting surface contact plane upon which said first projecting edge is configured to rest; and a second projecting edge disposed at an upper end of said chamfer portion and projecting beyond said leg plane, said second projecting edge defining a discrete contact surface for engaging a plank to be disposed between said pair of chamfer portions; arranging said at least one chamfer to accept a plank; placing said plank onto said base portion of said at least one chamfer; pouring concrete against said at least one chamfer and said plank; and curing said concrete.
  • 13. A plank and chamfer assembly for forming one or more precast panels on a casting surface, said assembly comprising:a chamfer comprising: a base portion comprising an upper surface and a lower surface, said base portion elongate along a lengthwise direction and including a pair of lateral edges that protect along a widthwise direction; and a pair of chamfer portions, each coupled to one of said pair of lateral edges of said base portion such that together said base portion and said chamfer portions define a unitary construction, each of said pair of chamfer portions substantially coextensive with said base portion along said lengthwise direction, each of said pair of chamfer portions comprising: a chamfer surface angularly coupled to said base portion; and a projecting edge disposed at a lower end of said chamfer portion, said projecting edge defining a discrete contact surface for engaging said casting surface such that a gap is defined between said lower surface of said base portion and a casting surface contact plane upon which said projecting edge is configured to rest; and a plank configured to be disposed in said chamfer such that upon placement of said plank into said chamfer, said projecting edge forms a seal with said casting surface.
US Referenced Citations (18)
Number Name Date Kind
1846196 Goldsmith Feb 1932 A
2858583 McEvoy et al. Nov 1958 A
2940152 Riehl Jun 1960 A
2953835 Armstrong et al. Sep 1960 A
2985938 Rappas May 1961 A
3782680 Hopkins Jan 1974 A
4042205 Herrell Aug 1977 A
4183497 Tamez Jan 1980 A
4387535 Corbo Jun 1983 A
5205942 Fitzgerald Apr 1993 A
5377447 Fritch Jan 1995 A
5397096 Nelson Mar 1995 A
5562272 McAbee et al. Oct 1996 A
5616271 Podgurski Apr 1997 A
5656194 Zimmerman Aug 1997 A
5671571 Braun Sep 1997 A
6322045 Andros Nov 2001 B1
6398180 Eyring et al. Jun 2002 B1
Foreign Referenced Citations (2)
Number Date Country
3638537 May 1988 DE
128626 Dec 1984 EP