Pull tab and method of manufacturing a pull tab

A pull tab for zippers is formed by a cord having a cord retaining member attached to one end of the cord and a socket in the top surface of the cord retaining member, and a plug attached to other end of the cord. The plug has a shape corresponding to the shape of the socket, so that the plug can fit securely within the socket, thus, forming a loop with the cord. A slidable locking device is placed around the cord, the locking device having an interior cavity corresponding to the shape of the cord retaining member, such that placing the plug into the socket and sliding the locking device over the cord retaining member locks the second end of the cord to the cord retaining member. In a method for manufacturing the pull tab, the plug and cord retaining member are continuously overmolded in one piece on a length of the cord, and then cut into pieces to form completed pull tabs.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a pull tab for zippers, as well as a method for manufacturing a pull tab. In particular the invention relates to a pull tab that can be applied directly to the zipper head, and to a manufacturing method for continuously overmolding a cord to form the pull tab.

2. The Prior Art

Pull tabs for zippers are usually formed by metal plates having an aperture in which the zipper head is mounted. These metal plates are often too small to allow for easy sliding of the zipper. This is especially true when the zipper pull becomes wet and slippery. Therefore, many manufacturers attach a cord having a larger pull on the end to the existing zipper pull. However, these additional cords are often too long to make pulling easy, and the manufacturing process is expensive and time consuming.

SUMMARY OF THE INVENTION

It is therefore an object of the invention to provide a zipper pull that can be applied directly to the zipper head, can be customized for a variety of sizes and decorations, and which can be produced simply and economically.

These and other objects of the invention are accomplished by a pull tab formed by a cord having a cord retaining member attached to one end of the cord and a socket in the top surface of the cord retaining member, and a securing device formed by a plug attached to other end of the cord. The plug has a shape corresponding to the shape of the socket, so that the plug can fit securely within the socket, thus forming a loop with the cord. Instead of a plug/socket attachment, any other suitable way to attach the end of the cord to the cord retaining member could also be used. A slidable locking device is placed around the cord, the locking device having an interior cavity corresponding to the shape of the cord retaining member, such that placing the plug into the socket and sliding the locking device over the cord retaining member locks the second end of the cord to the cord retaining member. The slidable locking device can be formed so that it snaps over the cord retaining member, or is held there with a friction fit.

The cord can be a woven cord, and the cord retaining member and plug are then over-molded onto the woven cord.

The cord retaining member can be formed in several shapes. In one embodiment, the socket is formed so that it extends through a proximal end of the cord retaining member. Thus, the cord is simply folded in a U-shape and the plug is placed in the socket, so that both ends of the cord are facing in the same direction.

In another embodiment, the socket can be formed extending through a proximal end of the cord retaining member, and/or with a slot for the cord extending through the distal end. In one embodiment, the second end of the cord is locked by placing the cord through the slot and placing the plug in the socket such that the two ends of the cord extend in opposite directions. In this embodiment, the cord is looped around the bottom of the cord retaining member. Preferably, there is a channel in the bottom surface of the cord retaining member for accommodating the cord when the slidable locking device is slid over the cord retaining member.

The slidable locking device can be made in any desired shape and made of any desired material. The locking device can be molded in two parts, which are then fused together.

The plug and socket have corresponding shapes, so that the plug fits securely within the socket. In one embodiment, the plug has a plurality of grooves and the socket has a plurality of protrusions corresponding to the grooves. This way, the protrusions prevent the plug from exiting the socket, even under force. In another embodiment, the plug and socket have a trapezoid shape. The wider end of the trapezoid is placed facing the direction of force, so that the plug cannot be inadvertently pulled out of the socket. Any other suitable set of corresponding shapes could be molded for the plug and socket as well.

The pull tab of the present invention can be applied directly to a zipper head without the need for a traditional zipper pull. This reduces cost and labor in manufacturing consumer items. The cord could be made to any desired length, depending on the needs of the end user.

The method for manufacturing the pull tab described above eliminates waste and labor by using a continuous molding process for a large number of pull tabs. Traditionally, each length of cord was required to be cut, the ends burned, and then individually molded onto the pull tab. In the present invention, a mold is used that has a mold cavity corresponding to a plug and a cord retaining member connected to each other. The cord is fed in from a reel so that the cord extends through the mold cavity. A channel can be made in the mold outside the mold cavity for the cord. Mold material is then injected into the mold cavity to form molded components around the cord. After the cord with the molded components is removed from the mold, the molded components are cut at a predetermined cutting point to form a cord having a cord retaining member on one end and a plug on the other.

In the method of the present invention, the cord can be fed into the mold continuously and the molded components are continuously molded on the cord in successive molding steps. As each molding step is completed, the cord is continuously pulled through the mold to create additional components.

The cutting of the components preferably occurs using a heated knife. This avoids any excess flashing being left on the molded components.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

Referring now in detail to the drawings and, in particular,FIGS. 1 and 2show a first embodiment of a pull tab10according to the invention. Pull tab10is comprised of a cord11having a cord retaining member12at one end and a plug13at the other end. Cord retaining member12and plug13are both over molded onto cord11, which can be a woven cord made of any suitable material. Cord retaining member12has a socket14molded therein, for receiving plug13when cord11is folded over itself, as shown inFIG. 2. In order to ensure a secure fit of the plug13into socket14, plug13has a series of grooves15encircling it, and socket14has a series of corresponding protrusions16that fit into the groove15when plug13is placed in socket14.

To attach pull tab10to a zipper head20, plug13is first threaded through a slidable locking cover17and then through the bar21, back through slidable locking cover17, and finally placed in socket13, as shown inFIG. 3. Then, locking cover17is slid down over cord retaining member12to lock plug13into socket13, as shown inFIGS. 4 and 5. Locking cover17can be molded in any desired shape and from any desired material. As shown inFIG. 5, the interior cavity24of locking cover17has a shape that conforms to the shape of cord retaining member12, so that cord retaining member12is securely held by locking cover17, as shown inFIG. 5. Locking cover17is equipped with a stop172on the proximal end, and another set of stops171on the distal end, to prevent cord retaining member from sliding out of locking cover17, even under stress. Locking cover17also has an oval-shaped channel173for accommodating cord11. Channel173has upper surface1732and lower surface1731, which can be configured of any desired dimension. A smaller channel173can create more friction on cord11and give it less space to move around. Grooves174can be cut into the top surface of locking cover17to assist in sliding cover17over cord retaining member12.

FIGS. 6-9show an alternative embodiment of pull tab10. Here, pull tab110is formed from a cord111connected to cord retaining member112at one end, and to plug113at the other end. Cord retaining member112has a socket114, which conforms to the shape of plug113. A channel119is formed into the underside of cord retaining member112, to accommodate cord111as well. In this embodiment, plug113and socket114are in the shape of a trapezoid. However, other shapes are suitable as well.

In this embodiment, plug113is placed in socket114by placing cord111in channel119on the underside of cord retaining member112and bringing it up and around to the top side of cord retaining member112for placement in socket114. Cord retaining member112has a slot118on its top surface for accommodating cord111as it comes around and into socket114. The application of pull tab110to a zipper head120is the same as with pull tab10, as is shown inFIGS. 8-9. Here, cord111is fed through locking cover117and bar121of zipper head120, and back through cover117. Cord111is then placed in channel119on the underside of cord retaining member112, through slot118and plug113is placed in socket114. Then, slidable locking cover117is placed on cord111and slid down over cord retaining member112to lock plug113into socket114. In this embodiment, pulling on cord111actually causes plug114to seat more securely into socket114because the proximal edges of plug113press against the walls of socket114, creating a very strong and secure pull tab.

To manufacture pull tab10,110according to the invention, the cord retaining members and plugs are continuously over-molded onto cord11,111.FIGS. 10 and 11show the two different variations of pull tabs10,110during the production process. In the production process, cord retaining members12,112and plugs13,113are molded in one piece onto cord11,111. Then, the cord retaining member12,112and separated from the attached plugs14,114by cutting them across a dividing line43, thus separating each pull tab10,110from the continuous line.

The molding process for pull tab10is shown inFIG. 12. Here, cord11is fed from a roll25into a mold30having a mold cavity31matching the shape of cord retaining member12and plug13connected together. Once mold material is injected into mold cavity31and mold30is separated to free cord11, cord11is pulled through to a cutting station40, where it is cut along dividing line43by a heated cutting blade41, to prevent any flashing from being left on the parts. An automated cord pulling fixture50can be used to pull the cord along the assembly line to facilitate processing. After cutting, a completed pull tab10results. This production process can be entirely automated, so that a large number of pull tabs are produced quickly and efficiently, with little margin for error.

The sliding locking cover can be manufactured and assembled separately, so that it can be customized for various applications and customers.