Joints and connections – Rod to member to side – e.g. – plate – rod side – etc. – Intermediate member includes tubular part
Reexamination Certificate
1999-11-16
2001-05-08
Kim, Harry C. (Department: 3629)
Joints and connections
Rod to member to side, e.g., plate, rod side, etc.
Intermediate member includes tubular part
C403S234000, C403S260000
Reexamination Certificate
active
06227752
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to a failsafe weld-free weldless method of joining tubular elements and the connector fitting assembly for carrying out the method. The tubes, inserts and connector fittings used are not size, shape or material specific.
2. Description of the Prior Art
A variety of household and industrial products are fabricated from tubing. Such products include but not limited to, disability aids, metal furniture, serving carts, display units, scaffolding, etc.
Frequently tubular products are brazed or welded to ensure a strong joint. Some of these products include disability aids such as wheelchairs and walkers. Fatigue failures are common in these products at the heat-effected zone of the braze/weld joints. Clamping is another method of joining tubular elements. Tube clamping eliminates some of the problems associated with welded/brazed joints but is more expensive to execute and is not as aesthetically pleasing as utilizing connector fittings. Examples of clamping designs are diclosed U.S. Pat. Nos. 5,253,888, 4,294,561 and 4,039,263. The use of connector fittings greatly increases the structural strength and durability of the tubular joint, provides a failsafe connection and reduces fatigue failure. The connector fitting allows for easy component replacement, modular construction and product customization.
Tube connectors developed for rigidly joining tube sections in such products include compression fittings, as disclosed in U.S. Pat. Nos. 4,921,370 and 3,985,460, that do not positively lock in the inside diameter of one of the tubes and may rotate axially. Other types of tubular connector are described in U.S. Pat. Nos. 4,846,600 and 4,752,979. This design uses an eye bolt type fastener, a notched tube member and a screw to hold the assembly together. With this design, the tubes may distort when the screws are tightened securely and the joint may loosen over time. A design that uses a formed sheet metal nut that is pressed into the inside diameter of a tubular member is disclosed in U.S. Pat. No. 4,810,144. This design relies on spring tension of the teeth of the nut to grip the inside diameter of the tube when a screw is tightened. There is no positive locking, the nut may loosen and/or rotate within the tube. Another disadvantage of all three patented types described above is that the screw attached to the first tube section goes through one or both walls of the tube. This increases stress and deformation of the tube and leaves a screw head showing at the front of the tube. It is possible to crush or deform the tube by the action of substantial forces acting on the tubular walls when the screw is tightened.
SUMMARY OF INVENTION
The primary objective of the invention is to provide a simple, strong, durable weldless connector fitting assembly used to join two tubular members.
It is also an object of the present invention to provide a weldless tube connector that does not have the disadvantages inherent in the prior art tube connectors.
It is another object of the invention to provide a weldless tube connector that is simple in construction and economical to manufacture.
It is still another object of the invention to provide a weldless tube connector that is simple and convenient to assemble.
It is yet another object of the invention to provide a weldless tube connector that minimizes or totally eliminates radial distortion in the connected tubes.
It is a further object of the invention to provide a weldless tube connector that results in a reliable connection between tubes joined to each other at various angles.
It is still a further object of the invention to provide a weldless tube connector that greatly reduces fatigue failures between connected tube members.
It is yet a further object of the invention to provide a weldless tube connector that facilitates modular construction and product customization.
It is an additional object of the invention to provide a weldless tube connector that provides a weldless construction with high structural strength between hollow tubular members.
It is yet an additional object of the invention to provide a weldless tube connector that can be assembled by lay persons with conventional tools.
It is still an additional object of the invention to provide a weldless tube connector that is lighter in weight and requires fewer fasteners to assemble, reducing costs of assembly, weight and assembly time.
It is another object of the invention to provide a tubular assembly free of tube distortion at fastening points.
It is yet another object of this invention to provide a fail safe feature in tubular assemblies capturing an internal fastener by use of a transverse fastener.
It is another object of this invention to provide a weldless tubular assembly where one of the two joined tube members has no visible fastener.
It is yet another object of this invention to provide a tubular assembly that can join a tubular element of any shape to either another tubular element or to a solid element of any shape.
In order to achieve the above objects and others that will become apparent hereafter a failsafe weld-free weldless method of joining tubular elements in accordance with the invention includes the use of a first elongated cylindrical member defining a first axis and having a substantially uniform cross section defining a predetermined outer surface. A second elongated member defines a second axis and has at least one tubular end. Connector means is provided for interfacing with said predetermined outer surface for detachably connecting one end of said second member to an intermediate portion of said first cylindrical member and preventing rotation of each of said cylindrical members about their respective axes when assembled and for preventing radial forces from being applied solely to a localized region of at least one outer surface portion of either one of said members.
An example of an apparatus for forming rigid joints coupling lengths of tubular stock together includes a first tubular section or length of pipe to which a second tubular section or length of pipe is to be joined. A singular hole is provided through one wall. The second tubular section or length of pipe has a hole through both walls. A third component of the invention is a plug that is either threaded or has a captured nut. The last component is a connector fitting. The first end of the connector fitting has a radius that is complementary to the outside diameter of the first tubular section. A hole for a connecting screw runs through the centerline axis of the fitting. The opposite end of the fitting has a counterbore along the axis that allows for clearance to the screw head and a shoulder for the screw head to rest on. This opposite end has an outside diameter that is a close fit to the inside diameter of the second tubular section. A transverse hole is positioned in the fitting.
The insert is positioned into the first tubular section, aligning the threaded hole with the singular hole in the tubular section. A screw is inserted into the connector fitting, with the head of the screw resting on the shoulder of the counterbore. The screw is inserted into the threaded hole of the insert and tightened securely. The second tubular section is then installed over the opposite end of the connector fitting, aligning all through holes. A fastener is placed through the holes to capture the connector fitting with the second tubular section. Should the screw in the insert loosen, it still cannot disengage due to the position of the through holes.
The tubular sections are not limited to specific material, shape or size. The insert and connector fitting may vary in size and shape and may be machined, cast or molded and may be of various materials. The angle of engagement is not limited to 90 degrees (perpendicular). The fastener may be of various types such as screw and nut, sex bolt, spring pin or rivet.
The proposed connector fittings allows for weldless construction, high structural strength, increased durability, smaller packagi
Da International, Ltd.
Kim Harry C.
Lackenbach Siegel Marzullo Aronson & Greenspan P.C.
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