METHOD AND APPARATUS FOR INJECTION MOLDING END STOPS ON SLIDE FASTENERS

Abstract: A method of and apparatus for applying end stop members (22) by injection molding to a slide fastener (10) having rows of coupling elements (14) on opposed stringer tape edges (13), a predetermined length of each of these tape edges (13) being held upright or substantially vertical to the plane of the tape web (12′) and embraced by end stops (22) molded in place with that predetermined length of tape edges (13) maintaining alignment with its neighboring contiguous tape edge (13) outside the molded end stop (22).

Description: This invention relates to a method of applying injection-molded end stop members to slide fasteners and an apparatus for carrying this method into practice. Fluidtight, i.e. airtight or watertight, slide fasteners are known, as the name implies, for their capability of sealing against leakage under various environmental conditions. Such a fluidtight fastener is f.i. known from US-A-3,005,247. The seal is effected along confronting longitudinal edges of two opposed stringer tapes when they are brought into abutting relation to each other by a slider member. To this end, the longitudinal tape edge is beaded or folded on one side upon which is mounted a row of coupling elements typically of a discrete formation, each element being covered by a sealing strip. The folded tape edge must be spaced a sufficient distance apart from the upper surface of the tape web such that the slider can move smoothly along and couple or uncouple the opposed fastener stringers. Therefore, the tape edges are, particularly in uncoupled condition, unstably movable with respect to the plane of the fastener, but are required in coupled condition to assume substantially upright position. When applying end stops as by injection-molding to such tape edges at the top or bottom end portion of the tape, care must be taken so that the lengths of the tape edges to which the end stops are applied maintain such upright position throughout the injection-molding operation to ensure alignment with ensuing contiguous lengths of exposed tape edges. Failing this would result in warped or displaced coupling elements that neighbor the end stops, thus eventually in malfunctioned or defective slide fasteners. With the foregoing difficulties in view, the present invention provides a method of and apparatus for applying end stop members for slide fasteners by injection molding which will enable the end stop to be molded in place over a predetermined length of element-carrying tape edges while the latter are maintained in proper upright position and in alignment with contiguous neighboring coupling elements. According to a first aspect of the present invention, there is provided a method of applying end stop members by injection molding to a slide fastener having a pair of stringer tapes each carrying along its inner longitudinal edge a row of coupling elements, said method comprising: supporting a predetermined length of said longitudinal edge in a position substantially vertical to the plane of the tape; injecting an end stop forming material to flow in a direction opposite to the position in which said longitudinal edge is supported; and molding an end stop in place with said predetermined length of said edge maintaining alignment with its neighboring contiguous tape edge outside said end stop. According to a second aspect of the present invention, there is provided an apparatus for applying end stop members by injection molding to a slide fastener having a pair of stringer tapes each carrying along its inner longitudinal edge a row of coupling elements, said apparatus comprising: a pair of molds movable toward and away from each other and defining therebetween a molding chamber, there being an opening centrally between said molds communicating with said chamber; and a plurality of supports extending from each of said molds into said chamber in spaced parallel relation to the plane of the tape, each of said supports supporting a predetermined length of said tape edge to be molded in a position substantially vertical to the plane of the tape and in alignment with its neighboring contiguous tape edge. Many other advantages, features and additional objects of the present invention will become manifest to those versed in the art upon making reference to the detailed description and the accompanying drawings in which two preferred embodiments incorporating the principles of the present invention are shown by way of illustrative example, in which like reference numerals refer to like or corresponding parts throughout the several views. Figure 1 is a fragmentary perspective view of a pair of fluidtight fastener stringers to which a top end stop is being applied according to the invention; Figure 2 is a view simlar to Figure 1 but illustrating the stringers to which the end stop has been applied; Figure 3 is a side elevation of Figure 2; Figure 4 is a plan view, partly sectional, of Figure 1; Figure 5a, 5b and 5c are cross-sectional views taken on the line V - V utilized to explain the steps of applying an end stop by injection molding; Figure 6 is a fragmentary sectional view of one of a pair of stringers, showing a modified supporting means; Figure 7 is a plan view, partly sectional, of a bottom end portion of a fluid-tight slide fastener to which an end stop is applied; Figures 8a and 8b are cross-sectional views taken on the line VIII - VIII of Figure 7 and utilized to explain the molding operation; Figure 9 is a fragmentary perspective view of a bottom end portion of the fluid-tight slide fastener to which an end stop has been molded in place; Figure 10 is a fragmentary perspective view of a bottom end portion of a concealed slide fastener to which a bottom stop has been injection molded; Figure 11 is a side elevational view of the concealed slide fastener, with a slider being pulling all the way to the bottom end stop; Figure 12 shows the manner in which the bottom end stop is injection molded; Figure 13 is a fragmentary perspective view of a top end portion of the concealed slide fastener to which a pair of top end stops have been injection molded; and Figure 14 shows the manner in which one of the top end stops is injection molded on the respective tape. Refering now to the drawings and Figure 1 in particular, there is shown a portion of each of a pair of identical stringers constituting a slide fastener 10 which is suitable for fluidtight applications. Since the stringers are identical in form and construction, it should suffice here to describe one of them. The stringer designated at 11 comprises a support tape 12 carrying on and along its inner longitudinal edge 13 a row of coupling elements 14 which is illustrated in the present embodiment to be of a discrete formation. Each individual element 14 has a coupling head portion 14a engageable with the corresponding head on the mating or opposite tape 12 and a heel portion 14b disposed remote from the head 14a and covered by a sealing clamp 15. The tape edge 13 to which the row of coupling elements 14 is secured is folded to provide a sealing abutment 16 with the opposite tape edge 13 to establish a seal against leakage in a manner well known in the art. As is also known, the tape edges 13 are raised with the coupling elements 14 above the surface of the web of the tape 12 to provide a clearance 17 for the passage of a slider 18 shown in Figure 2. The slider 18 is conventional in that it has a slider body 19 defining therein a guide channel (not shown) for the passage therethrough for the opposed rows of coupling elements 14 to come into or out of engagement with each other, and it has a pull tab 20 with which to manipulate the slider 18. The movement of the slider 18 is limited or stopped at the top end 21 of the stringer 11 by an end stop 22, as better shown in Figures 2 and 3, which is applied by injection molding in accordance with the invention. It is important for reasons set out above that the end stop 22 is molded in place over a predetermined length of tape edges 13 including coupling elements 14 while that length is maintained in upright position relative to the plane of the tape web 12′ and in alignment with the contiguous, neighboring row of elements 14. To this end, according to the method of the invention, a predetermined length of a tape edge 13 carrying a row of coupling elements 14 is supported in a position substantially vertical to the plane of the tape web 12′ as shown in Figure 5a; an end stop forming material is injected to flow in a direction opposite to the position in which the tape edge 13 is supported as shown in Figure 5b; and an end stop 22 is molded in place as shown in Figure 5c and Figure 2 with that predetermined length of tape edge 13 maintaining alignment with its neighboring contiguous tape edge 13′ (Figure 2) outside the end stop 22. Apparatus employed to carry this method into practice is schematically shown in Figure 1 and generally designated by 30 which comprises a pair of first and second molds 31, 32 horizontally movable toward and away from each other and a spacer block mold 33 separating the opposed tape edges 13, the molds 31, 32 and 33 defining therein a molding chamber 34. An opening 35 is provided centrally between the two molds 31 and 32 communicating with the chamber 34 for introducing thereinto a molding material M from a nozzle 36 connected to an injection cylinder 37. Each of the molds 31, 32 has a plurality of support pins 38 spaced apart a distance corresponding to the pitch of the elements 14 and extending into the chamber 34 in spaced parallel relation to the plane of the tape web 11′. The pins 38 are adapted to support the clamped heel portion 14b of each of the coupling elements 14 so that the length of the tape edge 13 to be molded together with the end stop 22 is maintained during molding of the latter in upright position as desired. The opening 35 is located in a position such that the material M flows from above in a direction opposite to the position of the support pins 38, orienting the flow not to affect the support of the tape edges 13. Upon completion of the molding operation, the first and second molds 31, 32 are separated as shown in Figure 5c with a residual gate 39 removed. To facilitate removal of this gate 39, the opening 35 is tapered toward the chamber 34, or conically formed as shown in Figure 1. To ensure stronger support for the tape edges 13 to be molded, the support pin 38 may be made larger and further provided with a recess 38′ for stably receiving the heel portion 14b of the element 14, as shown in Figure 6. Figures 7, 8a and 8b inclusive show an apparatus for molding a bottom end stop 22′ (Figure 9) onto the fastener 10, the apparatus being the same as that in Figure 1 except that the block 33 is precluded as this is not required because the opposed tape edges 13 at the bottom end of the fastener 10 are brought together in abutting relation to each other as better shown in Figures 8a and 8b. Each of the molds 31, 32 is provided around its inner periphery below the support pin 38 with a recess 40 for forming a peripheral fin 41 which serves to reinforce the bond of the end stop 22, (22′) to the tape web 12′. Figures 10, 11 and 13 show a concealed slide fastener 10′ including a pair of stringers 11, 11. Each stringer 11 includes a support tape 12 carrying on and along its inner longitudinal edges 13 a row of coupling elements 14′ in the form of continuous coiled filament. Alternatively, the coupling elements 14′ may be discrete. The support tape 12 may be woven or knit fabric. The tape edge 13 to which the row of coupling elements 14′ is secured is folded to provide an abutment 16′ engageable with the corresponding abutment of the tape edge 13 of the companion stringer 11 to conceal the opposed rows of coupling elements 14′, 14′ from the under side (Figures 10 and 13) when the slide fastener 10′ is closed, in a manner well known in the art. The movement of a slider 18 is limited or stopped at opposite ends of the slide fastener 10′ by a bottom end stop 22′ and a pair of top ends stops 22, 22, as shown in Figure 11. Each end stop 22′, 22 is applied to the tape edge 13 by injection molding in accordance with the invention. Since the row of coupling element 14′ is supported on the folded tape edge 13 as floating from the general plane of the tape 12, it is necessary to support the row of coupling elements 14′ by the support pins 38, while the end stop or stops 22, 22′ are injection molded, as shown in Figures 12 and 14. Figure 12 illustrates the manner in which the bottom end stop 22′ is injection molded as each row of coupling elements 14′ is supported by the respective support pin 38. The top end stops 22, 22 are injection molded separately, as shown in Figure 14 in which the molding of only one top end stop 22 is illustrated for clarity.

Claims: A method of applying end stop members (22), (22') by injection moulding to a fluid tight slide fastener (10) having a pair of stringer tapes (12), (12) each carrying along its inner longitudinal edge (13) a row of coupling elements (14), each of said coupling elements (14) having a coupling head portion (14a) engageable with a corresponding head (14a) on the mating tape (12) and a heel portion (14b) disposed remote from the head (14a), said longitudinal edges (13) being raised with the coupling elements (14) above the surface of the stringer tapes (12) to provide a clearance (17) for the passage of the slider (18), said method comprising: maintaining a predetermined length of said longitudinal edge (13) in a position substantially rectangular to the plane of the tape (12) by supporting the heel portion (14b) of the coupling elements (14); injecting an end stop forming material (M) from above centrally with respect to said opposing longitudinal edges (13); and molding an end stop (22), (22') in place with said predetermined length of said edge (13) maintaining alignment with its neighbouring contiguous tape edge (13) outside said end stop (22). Apparatus for carrying out the method according to claim 1, said apparatus comprising: a pair of molds (31), (32) movable toward and away from each other and defining therebetween a molding chamber (34), there being an opening (35) centrally between said molds (31), (32) communicating with said chamber (34); and a plurality of supports (38) extending from each of said molds (31), (32) into said chamber (34) in spaced parallel relation to the plane of the tape, each of said supports (38) supporting a heel portion (14b) of one of said coupling elements. Apparatus according to claim 2, said supports (38) being spaced apart a distance corresponding to the pitch of said coupling elements (14). Apparatus according to claim 2, each of said supports (38) being in the form of a pin having a recess (38′) for receiving the heel portion (14b) of said coupling element (14). Apparatus according to claim 2, further including a spacer block mold (33) separating the opposed tape edges (13), (13). Apparatus according to claim 2, each of said molds (31), (32) having an internal peripheral recess (40) below said supports (38). Apparatus according to claim 2, said opening (35) being tapered toward said chamber (34). Apparatus according to claim 2, said opening (35) being located so as to direct the flow of a molding material (M) in a direction opposite to the position in which said tape edges (13) are supported.

Inventors: KUSAYAMA, MASAHIRO
Applicants: YOSHIDA KOGYO K.K.
Application year: 1987
Main classification: B29C45
IPC codes: B29C45, A44B19, B29D5, B29L5