Wireworking – Article making or forming – Electric lamp or electric space discharge device electrode
Reexamination Certificate
2000-10-04
2002-07-23
Larson, Lowell A. (Department: 3725)
Wireworking
Article making or forming
Electric lamp or electric space discharge device electrode
C140S112000
Reexamination Certificate
active
06422271
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to clamp rings, and more particularly to devices and methods for automated production of clamp rings.
BACKGROUND OF THE INVENTION
Clamp rings have become a popular device for creating wreaths and similar items. As is well known, clamp rings typically have a spine in the shape of a ring to which are attached a number of spaced clamps used for holding material (e.g., boughs, decorations, and the like) to the ring. The spine and clamps are usually made from wire, with the spine wire normally being of a heavier gauge than the wire used to make the clamps (often called “rib” wire). The spine therefore provides sufficient strength and rigidity to the wreath while the clamps can be bent around material to be held to the spine. The clamps can be bent by hand, by a pair of pliers or other hand tool, or by a machine adapted for bending the clamps about the material to be held. Although a number of different clamp shapes exist, clamps are typically U-shaped with two legs and a back attached to the spine. Typically, the clamps are welded to the spine in any conventional manner.
As a result of the popularity of the above-described wire clamp ring, various devices and methods have been developed for producing such clamp rings more rapidly and reliably. One such device is disclosed in U.S. Pat. No. 5,829,490 issued to Kilbane. In the Kilbane device, a spine wire and a rib wire are fed perpendicularly to one another between male and female dies and adjacent to an anode in the male die. By actuation of a pneumatic cylinder, the female die is moved toward the male die, thereby cutting the rib wire and bending the rib wire into a U-shape between the dies to form a rib (a clamp) of the clamp ring. After this movement, a second pneumatic cylinder is actuated to bring a welding electrode into contact with the crossed rib and spine wires. An electrical current passed through the electrodes and wires then welds the rib wire to the spine wire. Next, both pneumatic cylinders retract to permit the spine wire and rib to be moved out from between the dies in preparation for the next rib forming and welding cycle. Because the spine wire fed to the dies is bent in an arc, a ring is eventually produced having the desired spaced-apart clamps welded thereto. After the ring is completed, the spine wire is cut and the wire clamp ring can be completed by welding the ends of the ring together.
Although conventional clamp ring manufacturing devices represent a significant improvement over manual assembly of clamp rings, they are not without their shortcomings. Significant factors in the success of clamp ring manufacturing device designs are the speed at which the devices can operate, the reliability of the ring-to-clamp connections made, the lifespan of the device, the manufacturing and maintenance costs of the device, and the ability of the device to produce different types of clamp rings. However, conventional clamp ring manufacturing devices fail to perform well in the majority of these areas.
For example, a common problem in the production of ring clamps is poor rib wire to spine wire attachment. In many instances, a rib falls off of the spine immediately after the welding operation is performed or soon thereafter. However, more serious problems can occur when the rib is partially attached to the spine and passes to the end user, who breaks the clamp off of the spine while attempting to manipulate the clamp. The partially-finished wreath is typically thrown away without disassembly, representing a waste of end user material and time. Even a small number of poor welds can frustrate the customer enough to return an entire shipment of clamp rings to the manufacturer. Therefore, the need to consistently and strongly attach clamps to the spine of the clamp ring is highly important.
The need for rapidly producing ring clamps is often at odds with the need to produce quality clamp welds. Specifically, weld quality in many prior art machines can drop significantly at faster machine speeds.
A source of clamp-to-spine attachment problems is the need to precisely control welding variables such as temperature, pressure, and welding time. In the conventional electrical welding systems commonly used in clamp ring manufacturing devices, the pressure at which the spine and rib wires are held against the electricity-supplying electrodes is important to creating a proper weld. However, because the actuator used must be strong enough to bend and form rib wires into clamps (e.g., into U-shaped clamps), the ability to precisely control actuator force is at odds with the use of larger, more powerful, and less precise actuators. The result is either less control over welding pressure or the inclusion of a second more precisely controllable actuator such as that employed in the device disclosed in the Kilbane patent mentioned above. Less control over welding pressure can result in poorer welds, while the addition of a second actuator adds complexity and expense to the device.
Due to the cyclical motion of clamp ring manufacturing machines and their often constant operation, the chances of machine breakdown can be high. As noted in the Kilbane patent mentioned above, repeated torque loads can be imparted to the actuation device and can cause premature failure of the actuation device. Structure added to counteract destructive loading can add significant complexity and expense to the machine and/or can negatively affect overall system speed and performance in other ways.
A desirable feature of clamp ring manufacturing machines is the ability to manufacture rings having different sizes. Although some existing machines can produce such rings, they do so by employing complex mechanisms that can be difficult to adjust and are expensive to manufacture and maintain. For example, when the desired radius of a spine wire is changed by changing the relative positions of upstream wire forming rollers, the feed path of the wire is usually also changed. Because the spine wire must still be fed between the dies as described above, some conventional clamp ring manufacturing machines employ elaborate adjustment and positioning mechanisms for re-positioning the spine wire through the dies. These mechanisms are often difficult to manipulate and consume valuable user time that could otherwise be used for making ring clamps.
Although the above discussion and the following description and claims is with reference to ring clamps, it should be noted that the present invention is relevant to the production of similar products that may or may not be in the form of a ring (and can be straight or take any other shape desired). The present invention lies not just in the ability to manufacture ring clamps, but more broadly in a machine and method for producing elements having a spine of any shape to which is connected one or more ribs of any shape used as clamps for holding any material to the spine. Therefore, the term “clamp ring” as used herein and in the appended claims is intended to encompass similar devices having other shapes—whether resembling a ring or not. The connection between the spine and ribs is typically a welded connection of metal wires, but can be a brazed, soldered, glued, melded, or other connection of elongated elements made from any resilient material (e.g., plastic, composites, and the like) having any cross-section (e.g., round, oval, flat or ribbon-like, rectangular, square, polygonal, and the like) and size performing similar functions to the spine and ribs described above. Any material can be held to the spine, the material selected depending upon the application intended for the manufactured elements. Most commonly, the application is in making wreaths as will be described hereinafter by way of illustration only, wherein the material includes branches and/or other foliage. However, any other material can be used as desired.
In light of the problems and limitations of the prior art described above, a need exists for a clamp ring manufacturing apparatus and method in which ring clamps
Frick Daniel L.
Mitchell Gordon P.
Larson Lowell A.
Michael & Best & Friedrich LLP
Mitchell Metal Products, Inc.
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