US3723221A - Process for manufacturing weighted cord and the same - Google Patents

Abstract

A WEIGHTED CORD OR STRIP FOR CURTAIN USE, MANUFACTURED BY THE STEPS OF COATING A NOTCHED CORE MEMBER WITH A FOAMED THERMOPLASTIC SYNTHETIC RESIN, SUBJECTING THE SHEATHED CORE MEMBER TO AN EXTERNAL FORCE TO THEREBY CUT OR DIVIDE THE CORE MEMBER INTO CORE PIECES AT THE NOTCHED LOCATIONS, APPLYING A TENSILE FORCE UNDER HEATING CONDITION TO THE SHEATH WHICH IS THUS ELONGATED ALONG THE LONGITUDINAL DIRECTION WHEREBY THE CUT CORE PIECES ARE MOVED AWAY FROM EACH OTHER TO PROVIDE A FIXED SPACE BETWEEN ANY TWO ADJACENT CORE PIECES, AND FINALLY COOLING THE SHEATH TO BE CURED AT ITS ELONGATED CONDITION SO THAT THE CORE PIECES ARE MAINTAINED IN THE SPACED RELATION FROM EACH OTHER WITHIN THE SHEATH.

Description

YUKIO HAYASHI 3,723,221

PROCESS FOR MANUFACTURING WEIGHTED CORD AND THE SAME March 27, 1973 Filed Nov. 2, 1971 United States Patent 3,723,221 PROCESS FOR MANUFACTURING WEIGHTED CORD AND THE SAME Yukio Hayashi, Tokyo, Japan, assignor to Kabushiki Kaisha Kaikosha, Tokyo, Japan Filed Nov. 2, 1971, Ser. No. 194,861 Int. Cl. B29c 17/04 US. Cl. 156-229 3 Claims ABSTRACT OF THE DISCLOSURE A weighted cord or strip for curtain use, manufactured by the steps of coating a notched core member with a foamed thermoplastic synthetic resin, subjecting the sheathed core member to an external force to thereby cut or divide the core member into core pieces at the notched locations, applying a tensile force under heating condition to the sheath which is thus elongated along the longitudinal direction whereby the cut core pieces are moved away from each other to provide a fixed space between any two adjacent core pieces, and finally cooling the sheath to be cured at its elongated condition so that the core pieces are maintained in the spaced relation from each other within the sheath.

The present invention relates an improved weighted cord or strip, in particular relates to a process for fabricating a weighted cord adapted to be used for the lowest weighted edge of the curtain and a weighted cord fabricated by such process.

As well-known to those skilled in the art, there has been already proposed a weighted cord for such use, wherein a plurality of weighting metal pieces is supported on a core thread in such manner that they are arranged in series along the core thread with a uniform space between any two adjacent metal pieces and then the metal pieces are all sheathed with fabrics. This conventional cord, however, has the disadvantage that it is lacking in flexibility and therefore diflicult in maintaining the skirting in compliance with the pleats of the curtain. The further shortcoming of the prior weighted cord of the type described just above is in that the curtain cloth is apt to be soiled with the rust oozing from the metal pieces through the fabric sheath. .It has been further developed to use the synthetic resin sheath in place of the fabric sheath. This synthetic resin-sheathed weighted cord is also lacking in flexibility and therefore has no adaptability to the curtain cloth. In addition, such synthetic resin sheath becomes less in flexibility or elasticity under the low temperature condition.

The foregoing prior technique, further has the disadvantage of being time consuming and too costly for the step of supporting weighting metal pieces on the core thread with a uniform spacing between any two adjacent metal pieces and also the step of applying the fabric sheath over the metal pieces.

The present invention, accordingly, has for its principal object to provide a novel weighted cord of such structure that it may eliminate the above-mentioned disadvantages and process for manufacturing this novel weighted cord.

Another object of the present invention is to provide a novel weighted cord which is superior in flexibility or elasticity as compared with the prior fabric-sheathed weighted cord, so that it may fairly adjust the skirting of the curtain in compliance with the pleats of the curtain.

Still another object of the present invention is to provide a novel weighted cord in which the rust from the metal core is effectively prevented from oozing through the sheath.

These and other objects of the present invention may 3,723,221 Patented Mar. 27, 1973 be accomplished by the steps of forming depressions or dents on a core member at each fixed longitudinal interval, applying a sheath of foamed thermoplastic synthetic resin over said notched core member, subjecting the resultant sheathed core member to an external force of, for example, torsion, bending or deflecting, to thereby cut or divide said core member into small core pieces at the notched locations where the breaking is most likely to occur, thereafter applying a tensile or stretching force to said thermoplastic resin sheath under heating condition whereby said sheath is uniformly elongated along its longitudinal direction with the result that the cut core pieces are separated or moved away from each other to provide a fixed space between any two adjacent core pieces, and finally cooling said sheath to cure it at its elongated condition so that the core pieces are held or maintained in the spaced relation from each other within said sheath.

In accordance with an aspect of the present invention wherein the notched core member is firstly sheathed with the foamed synthetic resin and then ruptured at the notched locations by application of the bending or deflecting force, it is quite easy to cut or separate the core pieces away from one another with no necessity of using the core thread as in the prior art.

In another aspect of the present invention wherein the thermoplastic foamed synthetic resin sheath is elongated by the application of tensile force under heating condition whereby the cut core pieces are spaced or moved away from each other to provide a fixed space between any two adjacent core pieces and, thereafter, the sheath is cooled to be cured at its elongated condition where the core pieces are held or maintained in the spaced relation from each other within the sheath, the spacing between two adjacent core pieces may be predominantly controlled according to the applied tensile force. It has been further found that after the application of tensile force under heating condition, the sheath portions between each two adjacent core pieces are different in their cellular structure from the residual sheath portions so that there may be provided a unique ornamental design or appearance which has the alternate glossy patterns. This weighted cord manufactured by the present art may be preferably used for the lace curtain.

In accordance with still another aspect of the present invention wherein the core member may be continuously coated with the foamed synthetic resin, the manufacturing of the weighted cord may be accomplished with easy and high efliciency.

The present invention will be more fully understood by reference to the following detailed description thereof, taken in conjunction with the drawings, in which:

FIG. 1 is a schematic view illustrating a preferred embodiment of a novel process for manufacturing a weighted core according to the present invention;

FIG. 2 is an enlarged schematic elevational view of the principal sections utilized in the manufacturing plant shown in FIG. 1, with parts being broken away;

FIG. 3 is an elevational view illustrating a weighted code according to the present invention, with a part being broken away;

FIG. 4 is a top view showing a weighted code of the present invention, with a part being broken away;

FIG. 5 is a cross-sectional view taken along the line A to A of FIG. 3; and

FIG. 6 is a cross-sectional view taken along the line B to B of FIG. 3.

Referring now to FIGS. 1 and 2 in which various components of the core-manufacturing system according to the present invention are schematically illustrated, there is firstly prepared a roll 11 of a weighted core member having the diameter or thickness of about 2 to 8 mm.

This weighted core member is preferably made of a flexible wire of, for example, lead or lead alloy. The weighted core member 10 is delivered from its roll 11 and fed into impressing means where the weighted core member 10 is formed thereon depressions or dents at each fixed longitudinal interval. For this end, the impressing means comprises a pair of rollers or drums and 20 arranged in opposition to each other with a predetermined space therebetween which is substantially equal to or slightly larger than the diameter or thickness of the weighted core member 10. Formed around the rollers or drums 20 and 20 is integrally therewith a plurality of impressing edges which are extended radially and also equi-spaced circumferentially of the rollers or drums. The opposed rollers 20 and 20 are driven from a suitable drive means (not shown) so as to make rotations in opposite direction to one another in synchronization with the feed speed of the core member 10. Preferably, the interroller spacing may be adjusted in accordance with the thickness or diameter of the core member to be fed between the rollers or drums. It will be thus understood that the core member 10 is, upon passing through between the rotating rollers or drums 20 and 20, dented or depressed on opposed sides thereof at each fixed interval by means of the impressing edges which are equi-spaced around the rollers or drums. The core member 10 thus notched or recessed at each predetermined interval is successively introduced into an extruder 40 where a sheath or covering 50 of foamed synthetic resin is applied over the periphery of the core member 10 to thereby prepare a weighted core.

The foamed synthetic resin preferably used in the present invention may be prepared by mixing a powdery or pellet-formed thermoplastic synthetic resin of, for example, vinyl chloride, polyethylene, vinyl acetate chloride, vinyl acetate or the like, a plasticizer of, for example, dinormaloctyl phthalate, dioctyl sebacate, parafiin chloride and a foaming agent of, for example, diazoaminobenzole, azobis isobutyrodinitrile, dinitrosopentamethylenetetramine, sodium bicarbonate, ammonium carbonate and the like.

It is preferred to use the mixture of 100 parts of thermoplastic synthetic resin, 70 parts of plasticizer and 0.5 part of foaming agent. The preferred thickness of the foamed synthetic resin sheath 50 applied on the core member 10 is about 0.3 to 3.0 mm.

The weighted cord is then subjected to the torsional force, bending or deflecting force or the combination of these forces at a station 60 whereby the sheathed core member 10 is cut or divided into core pieces at the depressed or notched locations 113 where the breaking is most likely to occur. The station 60, for example, comprises a plurality of rolls or drums which are in series arranged in such a manner that they are alternately and laterally offset with respect to the cord-running direction. In such arrangement, the weighted cord having the core member 10 therein may pass back and forth between the rolls under the tensile force so as to take a sinuous path whereby the cord is subjected to the bending or defleeting force exerted thereon to cut or divide the core member 10 only into core pieces.

Thereafter, the weighted cord is successively placed in a station 70 where the weighted cord is subjected to a tensile or stretching force under heating. When the weighted core is applied with the tensile or stretching force under being heated condition by, for example, hot water or the like, the thermoplastic synthetic resin sheath 50 is uniformly elongated along its longitudinal direction whereby the cut core pieces are separated or moved away from one another to provide a fixed space between any two adjacent core pieces. The weighted cord is finally placed in cooling station in which the sheath 50 is cooled down to be cured at its elongated condition so that the core pieces are held or maintained in the spaced relation from each other within the sheath 50.

The treating condition of the weighted cord in the station 70 should be determined according to the kinds of the thermoplastic resin used therein and the spacing distance to be determined therein, for example, the foamed thermoplastic synthetic resin sheath of vinyl chloride is elongated up to 200% when passing through the 2 m. hot water bath of about C. at the velocity of 45 m./ min. and then cooled down in the water of 20 C.

Referring now to FIGS. 3 to 6 throughout, there is illustrated a weighted cord or strip which has been manufactured by the process as described just above. The sheath portions a each located at the spacing between any two adjacent core pieces 10 and 10 have such a cellular structure that all cells or cavities in these portions a are collapsed into the flattened forms with the result that these sheath portions a are dilferent in glossy appearance from the residual sheath portions b. It will be thus understood that the weighted cord of this invention has a unique ornamental appearance or pattern.

If desired, furthermore, elongated ribs 51 and 51 may be attached on the opposite sides of the weighted cord so as to extend along the length of the cord. These ribs 51 and 51 may serve as guide means to stitching the cord to the skirting of the curtain without kind of the cord.

While particular forms of the invention have been shown and described, it is to be understood that the invention is capable of many modifications. Changes, therefore, in construction and arrangement may be made without departing from the scope of the invention as given by the appended claims.

What is claimed is:

1. A process for manufacturing a weighted cord, comprising the steps of applying a sheath of foamed thermoplastic synthetic resin over a notched core member, subjecting an external force to the sheathed core member to thereby cut the core member only into small core pieces at the notched locations where the breaking is most likely to occur, thereafter applying a stretching force to said sheath under a heating condition whereby the sheath is uniformly elongated along its longitudinal direction with the result that the cut core pieces are separated away from each other to provide a fixed space between any two adjacent core pieces, and finally cooling the sheath to be cured at its elongated condition so that the cut core pieces are maintained in the spaced relation from each other within the sheath.

2. A weighted cord manufactured by the process defined in claim 1.

3. A weighted cord according to claim 2, wherein at least one rib is attached on the outer surface of the sheath so as to extend along the length of the cord.

References Cited UNITED STATES PATENTS 2,917,102 12/1959 Mahady 156268X 3,043,716 7/1962 Busse et al. 156-244 X EDWARD G. WHITBY, Primary Examiner U.S. Cl. X.R.

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