Patent Grant
8936134
The current application is directed to a plastic blow-molded step ladder.
The present invention relates generally to molded articles which may be blow molded such as a blow-molded ladder or a blow-molded staircase for a swimming pool.
Swimming pool ladders or staircases and various other articles have been made from a plastic material by a process known as “blow-molding,” as exemplified in commonly assigned U.S. Pat. No. 4,023,647 to Confer, commonly assigned U.S. Pat. No. 4,067,614 to Confer et al, and U.S. Pat. No. 4,166,833 to Schurman, all of which patents are hereby incorporated herein by reference. In the process of blow molding, a hollow thin-walled structure is formed having an exterior surface separated from an interior surface by the thin wall, and the hollow structure contains a fluid, in most cases air and/or water.
Walter, in U.S. Pat. No. 1,911,539, Doernemann, in U.S. Pat. No. 5,536,111, Troester, in U.S. Pat. No. 5,013,508, and Tokunaga, in U.S. Pat. No. 3,759,043, all disclose a three-dimensional polymeric structure having a male and a female interlocking component. Not one of these disclosures has both interlocking components on a single side of the structure. Moreover, these references disclose both interlocking components contacting the edges of the sides, which allow easier forces to separate the components. As such, none of these references discloses an apparatus that forms at least a male and a female interlocking component on a single side, and preferably not contacting an edge of the side, of the structure.
In commonly assigned U.S. Pat. No. 7,234,780; Lipniarski wrote, “A device and method for forming an indented female connector where the dimension of the indented female connector provides for removing a male molding component without damaging a set of internal ribs formed inside the female connector. A structure comprising an indented female blow-molded connector having a first wall having a top surface and a thickness, with the first wall surrounding an opening. At least one inner wall extends substantially perpendicular to the first wall and borders the opening. At least one rib is formed in the inner wall. A bottom wall is joined to the inner wall and the distance from the rib to the top surface is greater than the thickness of the first wall. The structure further comprising a male connector having a contact edge that, when positioned inside the indented female blow-molded connector, engage the at least one rib, such that the male connector and indented female blow-molded connector are releaseably joinable with one another. Structures can be made that use the indented female blow molded connectors and male connectors including braced stools having three or four legs.” This connection system requires the male component be inserted immediately into a female locking area (a.k.a., an immediate locking system), which is difficult for easy and secure assembly.
Since most blow molded polymeric materials have an immediate locking system, most blow molded polymeric materials having an immediate locking system also require additional interconnection devices be used to secure the assembly. Those additional interconnection devices include and are not limited to rods, screws and other conventional interconnection devices. See U.S. Pat. No. 6,769,513.
In commonly assigned U.S. Pat. No. 8,202,018, Lipniarski wrote, that “invention is directed to a blow molded plastic object having a female interconnection system comprising a receiving area and a locking area. We are aware of one patent that discloses a similar a female interconnection system. That patent is commonly assigned U.S. Pat. No. 6,190,600; which is hereby incorporated by reference. In that patent, Lipniarski wrote, ‘The present invention relates to an apparatus that forms a polymeric structure. The apparatus has a mold plate, a circular trench, a male and female interconnect, a vertical gap filler, and a cylinder. The mold plate has a predetermined geometric design. The circular trench is in the mold plate and the difference between the outer diameter and the inner diameter of the circular trench is a distance D. The male interconnect and the female interconnect are interspaced between each other. Each interconnect rotates within the circular trench and has a base and an interconnection portion. Each base has a width D and slidably mates to the mold plate. Each interconnect portion has a minimum width W which is less than D. The male interconnect portion protrudes downwards relatively from its base to a distance P, likewise the female interconnect portion protrudes upwards relatively from its base to a distance P. The vertical gap filler aligns with the circular trench and has a foundation and an extension. The extension has a width greater than W, a height greater than 2P, and protrudes upwards and downwards from its foundation. The cylinder rotates each interconnect to a predetermined position and raises the vertical gap filler so the foundation connects to the mold plate before any polymeric material is applied to the apparatus to form the polymeric structure. Once the polymeric structure is formed, the cylinder lowers the vertical gap filler until the extension is below the mold plate a distance greater than P and rotates each interconnect so the polymeric structure can be removed from the apparatus.”
The claimed device in U.S. Pat. No. 6,190,600 is a mold for creating a first blow molded object that had a first male structure having a first extension and a first block and a first female structure having first receiving area and a first inhibiting area; and a second blow molded object that had a second male structure having a second extension and a second block and a second female structure having second receiving area and a second inhibiting area. Thereby the first blow molded object and the second blow molded object could have the first male structure inserted into the second receiving area and the second male structure inserted into the first receiving area. Rotating the first blow molded object in relation to the second blow molded object so the first male structure slides into the second inhibiting area and the second male structure slides into the first inhibiting area. The first and second inhibiting areas have no blow molded locking mechanism to secure the respective male structures in the inhibiting areas. Instead the inhibiting areas rely on the walls (which surround [that means a back wall] the male structure except where the male interconnect slides from the receiving area to the inhibiting area and the male extension that protrudes through an opening in the female inhibiting area) to provide a friction fit to inhibit the male structure from releasing itself from the female structure. The lack of a locking mechanism is acceptable for wave dispersion systems but not for ladders which require a more secure system. The present invention solves this problem for blow molded structures that require a secure locking mechanism.
A ladder 10 having
The ladder as described above
The ladder as described above further comprising
The ladder as described above wherein each top step support surface has a fourth step extension aperture capable of receiving a fourth step support's extension wherein the fourth step support has a fourth top step support section having (i) a fourth top front male step protrusion and a fourth top back male step protrusion, wherein each fourth top male step protrusion is capable of entering into a fourth step's top front and top back receiving areas and sliding into the fourth step's top securing area and (ii) a fourth step high aperture (a) positioned between the male step protrusion and the back support surface, and (b) having at least one side male protrusion capable of contacting a narrow section of a fourth step riser's upper hour-glass protrusion.
The ladder as described above wherein the right and left supports each have a rail opening that receives a rail's bottom hour-glass configuration.
a are images of risers and curve-about risers, respectively.
a and b are images of rail figures capable of being used in
The current invention is a step ladder that can have either three steps 10, for an in-ground pool configuration, or four steps 20, for an above-ground pool configuration. The three-step step ladder has three steps 15 and three risers 16, a right support 12 and a left support 14.
The right support 12 and the left support 14 are essentially mirror images of each other. Each support 12, 14 has a high aperture 30 and a low aperture 32 to respectively receive the riser's upper hour-glass protrusion 34 and lower hour-glass protrusion 36. The high aperture 30 (a) extends downwardly from each support's step support 40 and (b) has a front male protrusion 43 and a back male protrusion 42 that contacts the narrow section 38 of the upper hour-glass protrusion. The lower aperture 32 is positioned below the high aperture 30 and has a broad entry area 50 and a front riser secure area 52. The broad entry area 50 receives the lower hour glass protrusion 36;
the front riser secure area 52 has a front male protrusion 43a and a back male protrusion 42a that contacts the narrow section 38a of the lower hour-glass protrusion. This double aperture configuration stabilizes the risers, compared to the prior art risers that used only one aperture configuration.
Each riser is positioned to be received in a riser groove 60 on the bottom surface 61 of a corresponding step 15 positioned above the specific riser. Each step has a top surface 62, and a side surface 63 that separates the top and bottom surfaces.
Each non-top step right support 40 has a standard male step protrusion 70 having a neck area wherein the proximal end of the neck area protrudes from an essentially planar support surface 72 and an enlarged head section protrudes from the distal end of the neck area, the essentially planar support surface 72, a curve-about receiver 74, and a back-overhang area 76. The step 15 has, on its bottom surface 61, a corresponding female receiver having a back section 78 that receives the male step protrusion and a front section 79 that securely attaches to male step protrusion when the step is pushed back to contact the back-overhang area's back wall 777. The overhang surface 80 of the back-overhang area 776 has a male protrusion 82 that fits into a wide, deep groove 84 positioned on the step's top surface 62 when the step contacts the back-overhang area's back wall 777.
The top step right support 401 on the three-step step ladder configuration is similar to the other non-top step right supports, except it has no back-overhand area 776 and has a fourth step/curve-about extension aperture 740. The fourth step extension aperture 74a receives a fourth step extension 88. The fourth step extension 88 has riser apertures that are identical to the upper and lower apertures 30, 32, and a step support surface 89 having a front standard step protrusion 70a and a back standard step protrusion 70b that corresponds to female apertures positioned on fourth step's bottom surface.
The left step support 40a is similar to the right support, except there may not be a curve-about receiver 74.
Each support also has two pairs of two front rail apertures and two pairs of two back rail apertures. The lower set of front and back rail apertures are designed for the three-step step ladder and the upper set of front and back rail apertures are designed for the four-step step ladder. Each rail aperture has a top section 90 that receives the corresponding rail male protrusion and lower section 91 that secures the corresponding rail male protrusion 92 having an hour-glass configuration as described above.
The rail protrusions are extensions from the proximal end of the vertical section of the rail. At the distal end of the vertical section is a jigsaw-attachment configuration. The jigsaw attachment configuration has two quarter pie-shaped extensions 100a, b, opposing each other, and the extension's narrowest areas are separated by a center cavity 101 for a distance extending from the distal end to the proximal end for about half the length of the extension, and joined together 102 for the remainder of the extension. The extension area separated by the cavity has at least one protrusion 103. Likewise, the rail section 105 that essentially parallels the steps has a corresponding jigsaw attachment configuration 100c, 100d except it has an aperture 104 to receive the protrusion.
An interesting part of the risers 16 and steps 15 as used in this step ladder, is that the risers and steps can be altered between concave and convex configurations in the right and left supports 12, 14.
Optionally, the purchaser may want to add a curve about apparatus 200 to the right support 12. The curve about has a support 214 that is essentially identical to the left support except it has male back protrusions 215 that attaches to the right support 12 where the rails would attach if there was no curve-about section.
The curve-about risers 160, 160a are identical to the risers 16, 16a except the curve about-risers have a protrusion 636 positioned on the left side that securely fits into the broad entry area 50. Likewise, the curve-about steps 15a are identical to the corresponding ladder steps 15 except the left side has a protrusion that securely fits in the curve-about receiver 74.
The step ladder, three or four step configuration with or without the curve-about, can have platform supports 300. Each platform support has a first surface and second surface separated by a side surface. The first surface has a first groove 302a and the second surface has a groove 302b. The only difference between the grooves is that one extends further down into the platform than the other. That way the consumer can determine which groove to position the step ladder thereon and simultaneously determine how much water flow should flow under the ladder.
Obviously, the right and left support members can be reversed so that the left side can have the curve-about components; and both the right and left support members can have curve-about components extending therefrom. Moreover, the risers are flexible to allow the risers to be concave or convex.
This application claims priority to U.S. provisional patent application Ser. No. 61/684,323, filed on Aug. 17, 2012.
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| Number | Date | Country | |
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| 20140069742 A1 | Mar 2014 | US |
| Number | Date | Country | |
|---|---|---|---|
| 61684323 | Aug 2012 | US |
