CA1081412A - Method of forming coupling element for slide fastener - Google Patents
Method of forming coupling element for slide fastenerInfo
- Publication number
- CA1081412A CA1081412A CA339,052A CA339052A CA1081412A CA 1081412 A CA1081412 A CA 1081412A CA 339052 A CA339052 A CA 339052A CA 1081412 A CA1081412 A CA 1081412A
- Authority
- CA
- Canada
- Prior art keywords
- coupling element
- blank
- head
- molding
- slide fastener
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired
Links
Landscapes
- Slide Fasteners (AREA)
Abstract
ABSTRACT OF THE DISCLOSURE
A coupling element, such as a scoop formed from a synthetic polymer, for a slide fastener includes a head with a triangular side cross section bounded by a top surface and two downwardly converging bottom surfaces which extend at equal angles relative to legs of the coupling element. Leg sections adjacent the head are disclosed as being formed with oriented polymer for increased strength.
A coupling element, such as a scoop formed from a synthetic polymer, for a slide fastener includes a head with a triangular side cross section bounded by a top surface and two downwardly converging bottom surfaces which extend at equal angles relative to legs of the coupling element. Leg sections adjacent the head are disclosed as being formed with oriented polymer for increased strength.
Description
1081~1;2 ' The invention relates to slide fasteners and particularly to a method of forming coupling elements Eor slide fasteners.
One common slide fastener employs metal scoops ~r S coupling elements wherein each of the metal scoops has a tapered projection from the front thereof and a similarly shaped recess in the rear thereof for receiving the projection of a mating scoop; the tapered projection and the recess being in alignment parellel to the tape to which the metal scoop is secured. The bottom surface of the tapered projection on the scoop is thus substantially closer to the edge of the tape than the top of the recess such that the crosswise ~orces on the slide fastener tend to pivot the coupling element causing longitudinal stress on the edge of the tape.
According to the present invention there is provided a method of forming a coupling element for a slide fastener comprising forming a coupling element blank of flowable synthetic polymer resin wherein one of a head portion and a pair of 12g portions of the blank has an excess of the polymer resin, and molding the blank to extrude the excess polymer resin by laminar flow through the neck sections of the leg portions adjacent the head portion to orient the polymer in the neck sections and to form a head and a pair of legs for the coupling element.
An object of the invention is to provide a method of forming a coupling element for a slide fastener having an improved uniformity of stress loading of the element.
Another object of the invention is to provide a method of forming a coupling element aesthetically similar to metal scoops but having a specific geometry to permit manufacture with synthetic resins as well as requiring less material.
It is preferably also an object of the invention I_ .
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,. . .
to form a coupling element with a front locking projection and a back locking recess or pocket wherein the front and back coupling or loading surfaces are equidistant from the edge of a supporting tape.
An additional preferred feature is an open pocket in the coupling element.
Another feature of the invention is the orientation of a polymer resin in leg sections adjacent the head of the coupling element producing increased strength.
Other objects, advantages and features of the inven-tion will be apparent from the following description of the preferred embodiment taken in conjunction with the accompanying drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
Fig. 1 is a plan view of a slide fastener formed by a method in accordance with the invention.
Fig. 2 is a perspective view of a coupling element of the slide fastener of Fig. 1. -Fig. 3 is a perspective view of the element of Fig. 2 taken from a different angle.
Fig. 4 is a back view of the element of Figs. 2 and 3.
Fig. 5 is a bottom view of the element of Figs. 2, 3 and 4.
Fig. 6 is an enlarged plan view, partially in cross section, of a broken away portion of the fastener of Fig. 1 in an unloaded state.
Fig. 7 is a view similar to Fig. 6, but with the fastener in a loaded state.
Fig. 8 is a side cross section view taken along line 8-8 in Fig. 4.
~ Fig. 9 is a side cross section view of a blank used i in forming the coupling element of Figs. 2-5 and 8.
~ ~ Fig. 10 is a side cross section view of a variation ' - .... . .. . .
:' , , . ' . .
108~41Z
of the coupling element.
Fig. 11 is a side cross section view of another variation of the coupling element.
DESCRIPTION OF THE PREFERRED EMBODIMENT
As illustrated in Fig. 1, a slide fastener manu-factured in accordance with the invention includes a pair of carrier tapes 20 and 22 with rows of respective pluralities of interlocking coupling eiements 24 and 26 secured to the inner e~ges of the tapes 20 and 22. A slider 28 is slidably mounted on the coupling elements 24 and 26 for opening and closing the coupling elements. The tape 20 and coupling elements 24 form a left stringer, while the tape 22 and the coupling elements 26 form a right stringer. The left and right stringers are substantially mirror images of each other and together form a slide fastener chain.
As shown in Figs. 2-5, each of the coupling elements 24 (and the coupling elements 26, Figs.6 and 7) has a head 30 and a pair of parallel spaced legs 32 and 34 extending down-ward from opposite sides of the head 30. A tapered locking protrusion or projection 36 is formed on the front of the head - 30 and is defined by a generally horizontal top surface 38 of the element 24, a bottom surface 40 on the head 30 sloping upward from the front of the legs 32 and 34, and a pair of con-verging side surfaces 42 and 44 extending from about midway of the sides of the respective legs 32 and 34. A locking recess or pocket indicated generally at 46 in the back of the element 24 is bordered by a bottom inside surface 48 of the head 30 sloping downwardly from the rear of the element 24, and a pair of inside vertical surfaces 50 and 52 converging inwardly from the rear of the element 24. The bottom of the recess 46 opens into a slit 54 between the legs 32 and 34. As viewed in Fig.8, ~ the head 30 has a side cross section which is generally tri-; angular and bounded by the surfaces 38, 40 and 48; the surfaces 1081~12 40 and 48 converging downwardly at substantially the same angle relative to the horizontal or to the legs 32 and 34. Also mid-points of the surfaces 40 and 48 define a straight line 55, Figs. 6 and 7, generally perpendicular to the legs 32 and 34.
In forming the chain in Figs. 1, 6 and 7 the elements 24 and 26 are positioned with the inner edges of the tapes 20 and 22 received within the slots 54, Fig. 4, and between the leg portions 32 and 34. The heads 30 are spaced from the tapes 20 and 22 with the legs 32 and 34 extending perpendicular to the edges of the tapes. The coupling elements 24 and 26 are secured to the tapes 20 and 22 in a suitable manner, such as by adhesive bonding, ultrasonic bonding, dielectric bonding, or otherwise securing the legs 32 and 34.
The particular construction of the coupling element with a front locking projection and a rear locking pocket which opens into a slit 54 between the legs, thus forming an open pocket, results in utilization of less material for forming the coupling element as well as allowing leg to leg flexability and relatively easy attachment to the tape. The increased flex-ability allows for distribution of stress between the legs.
- As shown in Figs. 6 and 7, the projections 36 of the coupling elements 24 mate with the recesses 46 in the rear of the mating coupling elements 26, and vice versa. The engaging surfaces 40 and 48 on the front and back of each element are generally equidistant from the respective inner edges of the tapes 20 and 22; thus camming forces transverse the elements due to the crosswise forces on the tapes cancel and pivotal forces on the elements are substantially reduced. The tri-angular shape of the head 30 with the surfaces 40 and 48 ex-tending at substantially the same angle or slope producing in-line coupling provides a more efficient coupling between the elements 24 and 26 as well as more uniform stress loading of ~ the elements.
.~ , , .
' . , ~ : : . -The coupling elements 24 and 26 are formed from a synthetic polymer resin, such as one ~f the thermoplastic resins, nylc,n 6, nylon 6-6, polypropylene, polyethylene, polyester and acetal. As shown in Fig. 9, the coupling element is initially formed in a blank indicated generally at 56 which has a head portion 58 and leg portions (only one leg portion 59 of two leg portions shown). The blank has in one portion thereof a volume of resin in excess of that required for the corresponding portion of the finished product (herein after, simply "excess of resin"). For example, the blank may have an excess of synthetic resin in the head portion 58 such as in the area where the recess 46 is to be formed. Then the blank 56 is reformed, as indicated by ~he dashed lines, into the configuration of the coupling element of Figs. 2-7 by molding to extrude the excess synthetic resin from the head portion 58 downward through neck sections 60 and 62, Figs. 3,4 and 8, of the legs 32 and 34 adjacent the head 30. As indicated by the arrows 65 the ex-trusion produces laminar flow (i.e., flow in one direction) of the resin downward through the neck sections 60 and 62. Further, the molding die has constrictions in the front and back of the neck sections 60 and 62 to form indents 64 and 66 which reduce the cross sectional area of the neck sections 60 and 62 in-creasing the rate of laminar flow of the flowable resin material through the neck portions 60 and 62. Alternately the leg portions of the blank may have an excess of polymer resin while the head portion is deficient; the laminar flow being upward rather than downward through the neck portions 60 and 62.
Synthetic polymer resins have long chain molecules which are believed to be oriented during the laminar flow of the plastic resin to produce an orientation of the long chain molecules along the direction of the laminar flow. Additionally the laminar flow of the synthetic polymer resin may result in stratification in the crystalline structure of the polymer resin.
.. . .
1081~1Z
Such orientation or stratification results in substantially in-creased tensile strength o~ the neck sections 60 and 62 of the legs 32 and 34 adjacent to the head 30; thus the chance of breakage of the coupling elements at the neck portions 60 and 62, where the greatest amount of forces are concentrated during use of the slide fastener, is greatly reduced. The reduced neck section 60 and 62 also increase the flexibility of the head 30 making operation of the slide fastener easier than if such sections were not reduced.
Variations of the coupling elements are illustrated in Figs. 10 and 11 wherein numbers used to identify parts of the coupling element in Figs. 2-5 and 8 are used to identify sub-stantially identical parts of the variations in Figs. 10 and 11. In the coupling element of Figs. 2-5 and 8 excess of the molded material from the head portion is extruded through the neck sections 60 and 62 into the leg portions which are then expanded both forwardly and rearwardly. In the variation of Fig. 10 the legs are expanded only to the front, while in the variation of Fig. 11 the legs are expanded downwardly.
Also, the coupling elements can be made by a contin-uous molding process wherein they are molded in a flat config-uration joined by connecting threads embedded in the legs of the coupling elements; the legs subsequently being bent into the U-shape of the elements illustrated herein.
Since many variations, modifications, and changes in detail may be made to the described coupling elements and slide fastener and their method of manufacture, it is intended that all matter in the foregoing description and shown in the accompanying drawings be interpreted as illustrative and not in a limiting sense.
., , ~
.
. . . . . . .
One common slide fastener employs metal scoops ~r S coupling elements wherein each of the metal scoops has a tapered projection from the front thereof and a similarly shaped recess in the rear thereof for receiving the projection of a mating scoop; the tapered projection and the recess being in alignment parellel to the tape to which the metal scoop is secured. The bottom surface of the tapered projection on the scoop is thus substantially closer to the edge of the tape than the top of the recess such that the crosswise ~orces on the slide fastener tend to pivot the coupling element causing longitudinal stress on the edge of the tape.
According to the present invention there is provided a method of forming a coupling element for a slide fastener comprising forming a coupling element blank of flowable synthetic polymer resin wherein one of a head portion and a pair of 12g portions of the blank has an excess of the polymer resin, and molding the blank to extrude the excess polymer resin by laminar flow through the neck sections of the leg portions adjacent the head portion to orient the polymer in the neck sections and to form a head and a pair of legs for the coupling element.
An object of the invention is to provide a method of forming a coupling element for a slide fastener having an improved uniformity of stress loading of the element.
Another object of the invention is to provide a method of forming a coupling element aesthetically similar to metal scoops but having a specific geometry to permit manufacture with synthetic resins as well as requiring less material.
It is preferably also an object of the invention I_ .
~ ~ ; ,, :~, 1081~1Z
,. . .
to form a coupling element with a front locking projection and a back locking recess or pocket wherein the front and back coupling or loading surfaces are equidistant from the edge of a supporting tape.
An additional preferred feature is an open pocket in the coupling element.
Another feature of the invention is the orientation of a polymer resin in leg sections adjacent the head of the coupling element producing increased strength.
Other objects, advantages and features of the inven-tion will be apparent from the following description of the preferred embodiment taken in conjunction with the accompanying drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
Fig. 1 is a plan view of a slide fastener formed by a method in accordance with the invention.
Fig. 2 is a perspective view of a coupling element of the slide fastener of Fig. 1. -Fig. 3 is a perspective view of the element of Fig. 2 taken from a different angle.
Fig. 4 is a back view of the element of Figs. 2 and 3.
Fig. 5 is a bottom view of the element of Figs. 2, 3 and 4.
Fig. 6 is an enlarged plan view, partially in cross section, of a broken away portion of the fastener of Fig. 1 in an unloaded state.
Fig. 7 is a view similar to Fig. 6, but with the fastener in a loaded state.
Fig. 8 is a side cross section view taken along line 8-8 in Fig. 4.
~ Fig. 9 is a side cross section view of a blank used i in forming the coupling element of Figs. 2-5 and 8.
~ ~ Fig. 10 is a side cross section view of a variation ' - .... . .. . .
:' , , . ' . .
108~41Z
of the coupling element.
Fig. 11 is a side cross section view of another variation of the coupling element.
DESCRIPTION OF THE PREFERRED EMBODIMENT
As illustrated in Fig. 1, a slide fastener manu-factured in accordance with the invention includes a pair of carrier tapes 20 and 22 with rows of respective pluralities of interlocking coupling eiements 24 and 26 secured to the inner e~ges of the tapes 20 and 22. A slider 28 is slidably mounted on the coupling elements 24 and 26 for opening and closing the coupling elements. The tape 20 and coupling elements 24 form a left stringer, while the tape 22 and the coupling elements 26 form a right stringer. The left and right stringers are substantially mirror images of each other and together form a slide fastener chain.
As shown in Figs. 2-5, each of the coupling elements 24 (and the coupling elements 26, Figs.6 and 7) has a head 30 and a pair of parallel spaced legs 32 and 34 extending down-ward from opposite sides of the head 30. A tapered locking protrusion or projection 36 is formed on the front of the head - 30 and is defined by a generally horizontal top surface 38 of the element 24, a bottom surface 40 on the head 30 sloping upward from the front of the legs 32 and 34, and a pair of con-verging side surfaces 42 and 44 extending from about midway of the sides of the respective legs 32 and 34. A locking recess or pocket indicated generally at 46 in the back of the element 24 is bordered by a bottom inside surface 48 of the head 30 sloping downwardly from the rear of the element 24, and a pair of inside vertical surfaces 50 and 52 converging inwardly from the rear of the element 24. The bottom of the recess 46 opens into a slit 54 between the legs 32 and 34. As viewed in Fig.8, ~ the head 30 has a side cross section which is generally tri-; angular and bounded by the surfaces 38, 40 and 48; the surfaces 1081~12 40 and 48 converging downwardly at substantially the same angle relative to the horizontal or to the legs 32 and 34. Also mid-points of the surfaces 40 and 48 define a straight line 55, Figs. 6 and 7, generally perpendicular to the legs 32 and 34.
In forming the chain in Figs. 1, 6 and 7 the elements 24 and 26 are positioned with the inner edges of the tapes 20 and 22 received within the slots 54, Fig. 4, and between the leg portions 32 and 34. The heads 30 are spaced from the tapes 20 and 22 with the legs 32 and 34 extending perpendicular to the edges of the tapes. The coupling elements 24 and 26 are secured to the tapes 20 and 22 in a suitable manner, such as by adhesive bonding, ultrasonic bonding, dielectric bonding, or otherwise securing the legs 32 and 34.
The particular construction of the coupling element with a front locking projection and a rear locking pocket which opens into a slit 54 between the legs, thus forming an open pocket, results in utilization of less material for forming the coupling element as well as allowing leg to leg flexability and relatively easy attachment to the tape. The increased flex-ability allows for distribution of stress between the legs.
- As shown in Figs. 6 and 7, the projections 36 of the coupling elements 24 mate with the recesses 46 in the rear of the mating coupling elements 26, and vice versa. The engaging surfaces 40 and 48 on the front and back of each element are generally equidistant from the respective inner edges of the tapes 20 and 22; thus camming forces transverse the elements due to the crosswise forces on the tapes cancel and pivotal forces on the elements are substantially reduced. The tri-angular shape of the head 30 with the surfaces 40 and 48 ex-tending at substantially the same angle or slope producing in-line coupling provides a more efficient coupling between the elements 24 and 26 as well as more uniform stress loading of ~ the elements.
.~ , , .
' . , ~ : : . -The coupling elements 24 and 26 are formed from a synthetic polymer resin, such as one ~f the thermoplastic resins, nylc,n 6, nylon 6-6, polypropylene, polyethylene, polyester and acetal. As shown in Fig. 9, the coupling element is initially formed in a blank indicated generally at 56 which has a head portion 58 and leg portions (only one leg portion 59 of two leg portions shown). The blank has in one portion thereof a volume of resin in excess of that required for the corresponding portion of the finished product (herein after, simply "excess of resin"). For example, the blank may have an excess of synthetic resin in the head portion 58 such as in the area where the recess 46 is to be formed. Then the blank 56 is reformed, as indicated by ~he dashed lines, into the configuration of the coupling element of Figs. 2-7 by molding to extrude the excess synthetic resin from the head portion 58 downward through neck sections 60 and 62, Figs. 3,4 and 8, of the legs 32 and 34 adjacent the head 30. As indicated by the arrows 65 the ex-trusion produces laminar flow (i.e., flow in one direction) of the resin downward through the neck sections 60 and 62. Further, the molding die has constrictions in the front and back of the neck sections 60 and 62 to form indents 64 and 66 which reduce the cross sectional area of the neck sections 60 and 62 in-creasing the rate of laminar flow of the flowable resin material through the neck portions 60 and 62. Alternately the leg portions of the blank may have an excess of polymer resin while the head portion is deficient; the laminar flow being upward rather than downward through the neck portions 60 and 62.
Synthetic polymer resins have long chain molecules which are believed to be oriented during the laminar flow of the plastic resin to produce an orientation of the long chain molecules along the direction of the laminar flow. Additionally the laminar flow of the synthetic polymer resin may result in stratification in the crystalline structure of the polymer resin.
.. . .
1081~1Z
Such orientation or stratification results in substantially in-creased tensile strength o~ the neck sections 60 and 62 of the legs 32 and 34 adjacent to the head 30; thus the chance of breakage of the coupling elements at the neck portions 60 and 62, where the greatest amount of forces are concentrated during use of the slide fastener, is greatly reduced. The reduced neck section 60 and 62 also increase the flexibility of the head 30 making operation of the slide fastener easier than if such sections were not reduced.
Variations of the coupling elements are illustrated in Figs. 10 and 11 wherein numbers used to identify parts of the coupling element in Figs. 2-5 and 8 are used to identify sub-stantially identical parts of the variations in Figs. 10 and 11. In the coupling element of Figs. 2-5 and 8 excess of the molded material from the head portion is extruded through the neck sections 60 and 62 into the leg portions which are then expanded both forwardly and rearwardly. In the variation of Fig. 10 the legs are expanded only to the front, while in the variation of Fig. 11 the legs are expanded downwardly.
Also, the coupling elements can be made by a contin-uous molding process wherein they are molded in a flat config-uration joined by connecting threads embedded in the legs of the coupling elements; the legs subsequently being bent into the U-shape of the elements illustrated herein.
Since many variations, modifications, and changes in detail may be made to the described coupling elements and slide fastener and their method of manufacture, it is intended that all matter in the foregoing description and shown in the accompanying drawings be interpreted as illustrative and not in a limiting sense.
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Claims (5)
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:
1. A method of forming a coupling element for a slide fastener comprising forming a coupling element blank of flowable synthetic polymer resin wherein one of a head portion and a pair of leg portions of the blank has an excess of the polymer resin, and molding the blank to extrude the excess polymer resin by laminar flow through neck sections of the leg portions adjacent the head portion to orient the polymer in the neck sections and to form a head and a pair of legs for the coupling element.
2. A method as defined in claim 1 wherein the neck portions are narrowed during the molding to increase the rate of laminar flow through the neck portions, and wherein the molding of the blank includes the forming of a recess in the rear of the head portion of the blank.
3. A method as claimed in claim 1 wherein the head portion of the blank is formed with the excess of polymer resin, and the leg portions are expanded in length during the molding.
4. A method as claimed in claim 1 wherein the head portion of the blank is formed with the excess of polymer resin, and the leg portions are expanded in the front during the molding.
5. A method as claimed in claim 4 wherein the leg portions are also expanded in the back during the molding.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA339,052A CA1081412A (en) | 1976-05-24 | 1979-11-02 | Method of forming coupling element for slide fastener |
Applications Claiming Priority (3)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US05/689,414 US4236683A (en) | 1976-05-24 | 1976-05-24 | Coupling element for slide fastener and method of manufacture |
| CA278,828A CA1070486A (en) | 1976-05-24 | 1977-05-19 | Coupling element for slide fastener |
| CA339,052A CA1081412A (en) | 1976-05-24 | 1979-11-02 | Method of forming coupling element for slide fastener |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1081412A true CA1081412A (en) | 1980-07-15 |
Family
ID=27165089
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA339,052A Expired CA1081412A (en) | 1976-05-24 | 1979-11-02 | Method of forming coupling element for slide fastener |
Country Status (1)
| Country | Link |
|---|---|
| CA (1) | CA1081412A (en) |
-
1979
- 1979-11-02 CA CA339,052A patent/CA1081412A/en not_active Expired
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Legal Events
| Date | Code | Title | Description |
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| MKEX | Expiry |