Patent Application
20190301181
The present invention relates to concrete forms and, more particularly, to masonry connector cross ties that position opposing masonry shells in a level and plumb manor for use as STAY-IN-PLACE form work. Plastic cross ties constructed of a plastic pipe with two separate connectors attached to both ends act as a unit to position opposing masonry shells as part of a stay-in-place concrete form system. The pipe and connectors are snapped together with zip rods through the pipe eliminating the need for screws, nails, or glue reducing the assembly time of the cross tie unit.
Concrete wall construction is superior to wood stud wall construction by providing better fire resistance, higher strength against wind forces, and is more durable. However, concrete walls are unsightly, much harder to insulate, and form work costs are prohibitive.
A solution to the disadvantages of concrete wall construction over wood stud wall construction is illustrated and detailed in prior art documented in U.S. Pat. No. 9,388,574 Jul. 12, 2016 by Kevin Patrick Ryan—Stay In Place Concrete Form Connector.
In this prior art opposing masonry shells lined with vertical dovetail channels are spaced apart by plastic cross ties to form Stay-In-Place Concrete form work. The cross ties consist of a plastic pipe with two connectors attached on both ends of the pipe where the connectors are configured to engage the vertical dovetail channels molded into the masonry shells. This prior art addresses the disadvantages of concrete wall construction over wood stud wall construction as this type of construction is more easily insulated, is more attractive than an exposed concrete wall, and requires less form work labor as the masonry shell forms do not need to be removed.
Constructing a stay-in-place concrete form system is still more labor intense than constructing a wood stud wall system. To be competitive with wood stud wall construction any savings in labor time and cost would add to the justification for using this more expensive construction method.
In the prior art plastic cross tie units are created by fitting form connectors on both sides of a plastic pipe. The form connectors are then screwed or nailed to the plastic pipe to hold the pipe and the connectors together as one unit. Screwing or nailing the connectors together is a time consuming process making this stay-in-place concrete form system impractical.
It is therefore an objective of our invention to provide a mechanism of combining form connectors together with the plastic pipes that does not require screwing, nailing or gluing. A laborer in the field must be able to take a length of plastic pipe and snap a connector on both sides of the pipe without significant additional steps to create the cross tie assembly.
One possible solution to attach the connectors to the pipe would be to place a connector on both sides of the pipe and then thread a plastic cable tie strap through the pipe to hold the connectors from separating once snapped onto the ends of the pipe, creating a cross tie assembly with no screws, nails, or gluing. The concept of a tension strap that can be tightened easily but can not be easily withdrawn is illustrated and detailed in prior art documented in U.S. Pat. No. 3,118,200 Jan. 21, 1964 by Bell Charles Cox ET AL—Cable Strap. (commonly refereed to as zip ties)
Cable Straps are flexible and only work when pulled through a female connector in tension. Creating a stiff rod instead of a strap would allow two opposing rods with ratcheting teeth to be pushed into a pipe from either end. The two sets of teeth would ratchet together when pushed past each other in compression but these teeth would be sloped such that withdrawal of the rods from the pipe would be resisted by the interlocking teeth.
It is therefore an objective of our invention to combine prior art invention, concrete form connector, with improvements to the concept of ratchet tension cable straps (also refereed to as zip ties) to provide a stay-in-place concrete form cross tie assembly with snap together connectors using compression ratchet teeth rods crossing and engaging each other inside of a plastic pipe cross tie.
Prior art concrete form connectors require a laborer to interrupt assembly of the stay-in-place wall system to take time to nail or screw together cross tie assemblies, slowing down construction. As can be seen there is a need to snap together the cross tie assemblies quickly so that the laborer can concentrate on constructing the stay-in-place concrete form work.
In one aspect of the present invention, a method of connecting concrete form connectors in combination with a plastic pipe to create a cross tie assembly without the use of nails, screws or glue for use in a stay in place concrete form.
The plastic connectors are configured to fit tightly in a channel formed in masonry shells. The cross tie assembly and masonry shells are stacked to form a stay in place concrete form system.
The cross tie assembly consist of a plastic pipe and plastic connectors on both ends of the plastic pipe. The plastic connector has a plastic rod extending out from the mid height of the connector with ratchet teeth formed along the one side of the extended plastic rod. The plastic rod extension is configured to be inserted inside the plastic pipe and sized to fill half of the open area inside of the plastic pipe for the entire length of the pipe with the ratchet teeth facing the center of the pipe opening.
The plastic rod extension is configured with a cantilever spring arm extending down from the top of the rod extension. The ratchet teeth are molded in a position on the side of the cantilever spring arm. The cantilever spring arm allows the ratchet teeth to deflect inward away from the center of the pipe when forced inward by a pair of ratchet teeth passing each other with the teeth sloped in a manor to force the cantilever spring arm away from the center of the pipe. When the plastic rod extension is withdrawn from the pipe the ratchet teeth are sloped in a manor to allow the cantilever spring arm to return toward the center of the pipe locking two sets of mirrored ratchet teeth inter-meshed together preventing further withdrawal of the plastic rod extension.
Two identical dovetail plastic connectors with zip rod extensions are inserted into a plastic pipe, one from either end. The rod extensions cross as they are force toward each other through the pipe each filling opposite halves of the opening of the pipe. As the zip rods pass each other the cantilever spring arms with ratchet teeth are forced apart allowing the pairs of ratchet teeth to pass each other. As the zip rod extension are withdrawn the cantilever spring arms move back together locking the rod extensions together. The two dovetail plastic connectors and the plastic pipe are joined together to form a cross tie assembly.
The following detailed description is of the best currently contemplated modes of carrying out exemplary embodiment of the invention. The description is not to be taken in a limiting sense, but is made merely for the purpose of illustrating the general principles of the invention, since the scope of the invention is best defined by the appended claims.
Broadly, an embodiment of the present invention provides a mechanism to connect two concrete form connectors through a plastic pipe to create a stay-in-place concrete form cross tie assembly without the use of screws, nails or glue. The concrete form connectors are molded with an extension rod with ratchet teeth. The extension rods are sized to fit inside the plastic pipe with each rod filling half the area of the pipe opening. The extension rods are fashioned with cantilever spring arms with the ratchet teeth molding along the length of the spring arm. As two extension rods are inserted into the ends of the plastic pipe, one on each end, the spring arms are forced apart by the ratchet teeth passing in opposite direction sloped to force the spring arms apart. When the extension rods are pulled out of the plastic pipe the spring arms force the ratchet teeth together locking the assembly of two concrete form connectors and one plastic pipe into a cross tie assembly.
The cross tie assembly can then by used as part of a stay-in-place concrete form system constructed of masonry shells and plastic cross ties as documented in previous art.
The cross tie connectors come in three parts. The length of the plastic pipe can be modified as required to change the width of the concrete form opening. If the cross ties were formed as one piece then the width of the concrete form could not be easily modified. Combining the three parts as documented in previous art required screwing the three parts together.
Screwing, nailing, or gluing the three separate parts together is time consuming making the cost of this stay-in-place form system expensive.
One solution to resolve this problem would be to mold a ratchet cable tie as part of one of the two concrete form connectors. The second concrete form connector could then be molded with a female receptor to receive the ratchet cable tie. The ratchet cable tie could then be passed through the plastic pipe and then inserted and tightened to the second concrete form connector with a female receptor tensioning the two connectors and the plastic pipe together to form a cross tie connector assembly.
This solution is not practical as the ratchet cable tie is flexible and needs to be pulled trough the female receptor to tighten the parts together. A solution where ratchet teeth can connect parts together by pushing the parts together instead of pulling the end of a strap through a female receptor is ideal.
The present invention can ratchet together two sets or teeth by pushing two extension rods lined with ratchet teeth through a plastic pipe without the need for pulling the rods through a female receptor. The rods would be formed with cantilever spring arms that deflect in a manor enabling the ratchet teeth to pass each other when the rod is pushed into the plastic pipe, but the arms spring back to interlock the ratcheting teeth when the rods are withdrawn from the plastic pipe. The extension rods would be sized to fill half of the opening of the pipe. The pipe would confine the two rods together as they passed each other inside the pipe providing the force required to hold the ratcheting teeth together.
The three parts now joined together without the need for screws, nails, or glue could now be used as a cross tie assembly in a stay-in-place concrete form system using masonry shells lined with vertical dovetail channels.
Referring now to the figures. a split plate metal mold with injection ports is manufactured to produce injection molded polypropylene parts 100 in the configuration shown in
The dovetail shaped concrete form connectors 100 act in pairs as a connector to join masonry shells of inconsistent dimensions 300 together for use as stay in place concrete form work as shown in
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It should be understood, of course, that the foregoing relates to exemplary embodiment of the invention and that modifications may be made without departing from the spirit and scope of the invention as set forth in the following claims.
