METHOD AND APPARATUS FOR PRODUCING HOOKS ON HOOK-AND-LOOP FASTENERS

Abstract: An improved method and apparatus for producing hooks on hook-and-loop fasteners, wherein loops (l2) on a loop sheet (l0) are cut from the outside thereof on their one legs (l2 a ) near loop heads (l2 c ) by reciprocating first movable cutting comb teeth (30) of a first movable blade (l9) in a direction perpendicular to the axes of first stationary cutting comb teeth (22, 30) of a stationary blade (l8) while the loops (l2) are guided along the first stationary cutting comb teeth (22), thereby producing a hook (26) from each loop (l2) thus severed, and then the severed leg (l2 a ) of each severed loop (l2) is further cut from the outside of the loop (l2) near a foundation fabric (ll) by reciprocating second movable cutting comb teeth (33) of a second movable blade (20) in a direction perpendicular to the axes of second stationary cutting comb teeth (27) of the stationary blade (l8) while the severed leg (l2 a ) is held in one of the two adjacent guide grooves (24) defined in the stationary blade (l8).

Description: The present invention relates to a method of and an apparatus for producing hooks on surface-type fasteners known as hook-and-loop fasteners by cutting uncut loops on a base sheet on their one legs. According to a known method and apparatus disclosed in Japanese Patent Publication No. 42-l35ll, published August l, l967, and reillustrated here in Figures 7 and 8, a comb-like stationary cutter blade A of a given thickness and a pair of comb-like movable cutter blades B, B disposed on opposite sides of the stationary cutter blade A are inserted into loops C on a base sheet while the latter is fed along a path, and then the movable cutter blades B, B are horizontally reciprocated to cut the loops C on their one legs simultaneously at two different points, thereby producing hooks each of which has a relatively large loop-accepting passage or space substantially equal to the thickness of the stationary cutter blade A. The known practice, however, has various drawbacks: The cutter blades A, B must be narrow and thin enougth to pass through such small loops having a height of about 2 mm and hence they are hardly to manufacture at a low cost. The movable cutter blades B further need to be rigid enough to cut the loops of monofilament. Such rigid but thin movable cutter blades B are likely to be damaged and sometimes broken during cutting operation. The possiblity of cutter breakage increases as the cutting speed or the reciporcating motion of the movable cutter blades B is increased. Additionally, the thin stationary cutter blade A is liable to vibrate in resonance with the reciprocation of the movable cutter blades B, thus making it difficult to cut all the loops at the same points of severance. Consequently, the resulted hooks have non-uniform shapes and configurations and provide only a low strength of engagement when coupled with loops of a mating fastener part. A further disadvantage is in that the loop-accepting spaces of the hooks, which depend on the thickness of the stationary cutter blade A, can be adjusted only by replacing stationary cutter blade A with another stationary cutter blade having a different thickness. The present invention seeks to provide an improved method and apparatus for producing hooks on hook-and-loop fasteners, which can overcome or substantially eliminate the foregoing drawbacks of the known practice. The present invention further seeks to provide a method and apparatus for producing hooks on hook-and-loop fasteners by severing uncut loops twice on their one legs accurately at two different points by means of a loop cutter having a stationary blade and two movable blades, each of which is relatively thick and durable in construction, is free from resonant vibration and can be manufactured easily at a low cost. The present invention further seeks to provide a method and apparatus for producing hooks on hook-and-loop fasteners, which can provide various loop-accepting passages or spaces with the hooks. According to a first aspect of the present invention, there is provided a method of producing hooks on hook-and-loop fasteners, characterized by: (a) introducing a plurality of parallel spaced first stationary cutting comb teeth of a stationary blade into loops projecting from a foundation fabric of a loop sheet as the loop sheet is fed along a path; (b) cutting the loops from the outside thereof on their one legs at a first point near heads of the respective loops by reciprocating a plurality of parallel spaced first movable cutting comb teeth of a first movable blade in a direction perpendicular to the axes of the comb teeth while the loops are guided along the first stationary cutting comb teeth, thereby producing a hook from each loop thus severed; (c) guiding the severed leg and the hook of each severed loop to move in and along an adjacent pair of parallel spaced guide grooves defined in the stationary blade; and (d) further cutting the severed leg from the outside of each severed loop at a second point near the foundation fabric by reciprocating a plurality of parallel spaced second movable cutting comb teeth of a second movable blade in a direction perpendicular to the axes of a plurality of second stationary cutting comb teeth of the stationary blade while the severed leg is held in one of the two adjacent guide grooves. According to a second aspect of the present invention, there is provided an apparatus for producing hooks on hook-and-loop fasteners, comprising a sheet guide defining thereon a horizontal first passage and a downwardly inclined second passage for guiding along said first and second passages a loop sheet having a plurality of loops arranged in transverse rows and longitudinal tiers and each having a pair of legs interconnected by a head, and a loop cutter disposed adjacent to said sheet guide for cutting the loops twice on their one legs at two different points as the loop sheet is advanced along said first and second passages, characterized in that said loop cutter includes (i) a stationary blade having a plurality of parallel spaced first stationary cutting comb teeth extending in overhanging relation to said first guide path for being inserted in the loops in said tiers, a plurality of parallel spaced guide grooves extending downwardly from said first stationary cutting comb teeth along said second second passage and facing toward said second passage for receiving the loops after their first severance, and a plurality of second starionary cutting comb teeth defined at lower ends of said guide grooves; (ii) a first reciprocably movable blade slidably mounted on said stationary blade and having a plurality of parallel spaced first movable cutting comb teeth disposed above alternate ones of said first stationary cutting comb teeth for cutting the loops from the outside thereof on their one legs at a first point near the heads of the respective loops while the loops are guided along the remaining first stationary cutting comb teeth, and (iii) a second reciprocably movable blade slidably mounted on said stationary blade and having a plurality of parallel spaced second movable cutting comb teeth disposed below alternate ones of said second stationary cutting comb teeth for further cutting the severed legs from the outside of the severed loops at a second point near the foundation fabric while the severed legs are held in alternate ones of said guide grooves. Many other advantages and features of the present invention will become manifest to those versed in the art upon making reference to the detailed description and the accompanying sheets of drawings in which a preferred structural embodiment incorporating the principles of the present invention is shown by way of illustrative example. Figure l is a fragmentary cross-sectional view of an apparatus for producing hooks on hook-and-loop fasteners according to the present invention; Figure 2 is an exploded perspective view of a loop cutter of the apparatus shown in Figure l; Figure 3, appearing with Figure l, is an enlarged fragmentary end elevational view of a loop sheet having loops from which hooks are produced by the apparatus shown in Figure l; Figure 4A is a cross-sectional view taken along line IV - IV of Figure l, showing the loop cutter in a first or standby position before effecting first loop-cutting operation; Figure 4B is a view similar to Figure 4A, showing the loop cutter in a second position after the first loop-cutting operation; Figure 5 is a cross-sectional view taken along V - V of Figure l; Figure 6A is a cross-sectional view taken along line VI - VI of Figure l, showing the loop cutter in the first position before effecting a second loop-cutting operation; Figure 6B is a view similar to Figure 6A, showing the loop-cutter in the second position after the second loop-cutting operation; Figure 7 is a fragmentary plan view of a known apparatus; and Figure 8 is a cross-sectional view illustrative of the operation of loop cutter of the known apparatus shown in Figure 7. As shown in Figures l and 3, a loop sheet or tape l0 is composed of a foundation fabric ll and a multiplicity of projecting uncut loops l2 of thermoplastic synthetic resin monofilament interwoven or interknitted in the foundation fabric ll and arranged in rows and tiers at predetermined intervals or pitches. The loops l2 in transverse rows are longitudinally aligned in tiers. Each loop l2 has, as shown in Figure 3, a pair of legs l2 a , l2 b interconnected by an arcuate head l2 c , the legs l2 a , l2 b being spaced from each other transversely of the foundation fabric ll. The loop sheet l0 may be of the type, as shown in Figure 7, having a multiplicity of projecting loops arranged in transverse rows and longitudinal tiers, the loops in alternate transverse rows being trnsversely staggered by half the loop pitch in each transverse row, and the staggered loops in alternating transverse rows being longitudinally aligned in tiers. An apparatus l3 for producing hooks according to the present invention comprises a sheet or tape guide l4 for slidably supporting the loop sheet l0 which is continuously or intermittently fed along a longitudinal path by a suitable sheet feed mechanism (not shown). The loop sheet l0 as it is fed on and along an upper horizontal guide surface l5 of the sheet guide l4 turns around a downwardly sloping flat corner guide surface l6 and then is moved in a downward vertical direction, as shown in Figure l. The apparatus also includes a loop cutter l7 composed of a stationary blade l8 and a pair of upper and lower movable blades l9, 20 slidably disposed on opposite sides of the stationary blade l8. As shown in Figure 2, the stationary blade l8 includes a substatially rectangular body 2l and a plurality of equally spaced, parallel cutting teeth 22 in the form of a comb projecting horizontally from an upper longitudinal edge of the body 2l in overhanging relation to the sheet guide surface l5 (Figure l) for being inserted in the loops l2 and for cutting the loops l2, as described below. The comb teeth 22 have longitudinal axes transversely spaced by a distance equal to the half of the pitch or interval between each adjacent pair of loops l2 in one of transverse rows of the loops l2. The comb teeth 22 have a substantially square uniform cross-sectional shape throughout the length thereof and define therebetween a plurality of guide slots 23 opening toward the sheet guide l4 for receiving the legs l2 a , l2 b of the loops l2 as the loops l2 are advanced along the comb teeth 22. The stationary blade l8 further includes a plurality of guide grooves 24 extending contiguously from one or closed ends of the respective guide slots 23 downwardly across a bevelled surface 25 of the cutter body 2l. The bevelled surface 25 extends parallel to the corner guide surface l6 of the sheet guide l4 in confronting relation to the guide surface l6 so that the loops l2 after their first severance are advanced in and along the guide grooves 24. The guide groove 24 each have a width and a depth which are large enougth to alow passage of the cut loops l2 in such a manner as shown in Figure 5 in which the severed leg l2 a and a hook 26 which have been produced from each cut loop l2 are guidedly received respectively in two adjacent guide grooves 24 with the severed leg l2 a held in a posture suitable for a second severance made at a point near the foundation fabric ll. The stationary blade l8 has on its lower surface a plurality of cutting teeth 27 (Figure l) in the form of comb defining therebetween lower ends or outlets of the respective guide grooves 24, and an elongate channel 28 disposed adjacent to the outlets of the guide grooves 24 in communication with the latter and extending across the cutter body 2l in a direction perpendicular to the axes of the cutting teeth 22 for discharging cut debris 29 (one being shown in Figure l) produced during second loop-cutting operation. The upper movable blade l9 is slidably mounted on an upper surface of the stationary blade l8 and includes a plurality of parallel, equally spaced tapered cutting teeth 30 in the form of a comb. The comb teeth 30 are half in number of the comb teeth 22 of the stationary blade l8 and, as shown in Figure 4A, they are disposed above every other comb teeth 22. The loops l2 are guided along the next adjacent comb teeth 22 extending between the comb teeth 22 above which the comb teeth 30 are disposed and hence the comb teeth 30 are normally disposed on the outer side of the loops l2. The comb teeth 30 are laterally movable into a position above the adjacent comb teeth 22 for effecting a first loop severance. The movable blade l9 is driven in a reciprocating movement in a direction perpendicular to the axes of the teeth 22, 30, through an amplitude or stroke substantially equal to the spacing between axes of two adjacent comb teeth 22 of the stationary blade l8 so that each loop l2 is cut only on its one leg l2 a at a first point 3l (Figure 3) near the head l2 c of the loop l2. Each of the comb teeth 30 has a width substantially equal to the width of each comb tooth 22 of the stationary blade l8. Since the comb teeth 30 are normally positioned outside of the loops l2 to be cut, it is not necessary to make the comb teeth 30 thin enough to be received in the loops l2 before the loop severance as in the case of the known comb teeth B (Figure 7). Unlike the known comb teeth B, the comb teeth 30 are made thick and hence can be manufactured easily at a low cost, and are durable in construction. Between the comb teeth 30, there are defined a plurality of slots 32 (Figure 2) opening toward the sheet guide l4. The lower movable blade 20 which is disposed underneath the stationary blade l8 is structurally and functionally the same as the upper movable blade l9. More specifically, the lower movable blade 20 is slidably disposed on a lower surface of the blade body 2l and has tapered comb teeth 33 for further cutting, in co-action with the comb teeth 22, the loops l2 on their one legs l2 a at a point 34 (Figure 3) near the foundation fabric ll. The tapered comb teeth 33 are equally spaced by a plurality of slots 35 Figure 2) defined therebetween so that the comb teeth 33 are disposed below every other comb teeth 22 of the stationary blade l8, as shown in Figure 6A. The comb teeth 33 are normally disposed on the outer side of the loops l2 and are laterally movable in a position immediately below the next adjacent comb teeth 22 extending between the severed leg l2 a and the hook 26 of each loop l2 for further severing the severed leg l2 a (Figure 6A to Figure 6B). The upper and lower movable blades l9, 20 are assembled with the stationary blade l8 by means of three sets of bolts 36 and nuts 37 with three compression coil springs 38 disposed between and acting between the respective bolts 36 and the upper movable blade l9. The bolts 36 respectively extend successively through three holes 39 in the upper movable blade l9, through three oblong holes 40 in the stationary blade l8, and through three holes 4l in the lower movable blade 20. Each of the upper and lower movable blades l9, 20 includes an elongate guide ridge 42 extending perpendicularly to the axes of the comb teeth 30, 33 and slidably received in one of a pair of elongate guide recesses 43 defined in the upper and lower surfaces of the stationary blade l8. The movable blades l9, 20 thus assembled are reciprocably movable in unison in a direction perpendicular to the axes of the teeth 22 of the stationary blade l8. The reciprocating motion of the movable blades l9, 20 is limited by the length of the elongate holes 40. The loop cutter l7 is horizontally and vertically movable to adjust the positions of upper and lower pairs of the comb teeth 22, 30 and 22, 33 with respect to the sheet guide l4, thereby adjusting the distance d (Figure 3) between the first and second cutting points 3l, 34. With this adjustment, it is possible to vary loop-accepting passages or spaces of the hooks 26 in depencence on the distance d . Operation of the apparatus l0 of the foregoing construction is as follows: When the loop sheet l0 is fed on and along the upper guide surface l5 in a direction of the arrow 44 (Figure l), alternate comb teeth 22 of the stationary blade l8 are inserted into the loops l2 in longitudinal tiers. A further advancing movement of the loop sheet l0 causes the loops l2 to enter into a first cutting region or a path of reciprocating movement of the comb teeth 30 of the upper movable blade l9 (Figure 4A). Then the movable blade l9 is driven to shift its comb teeth 30 rightward from the position of Figure 4A to the position of Figure 4B, thereby cutting each loop l2 on its one leg l2 a at the first cutting point 3l (Figure 3) near the head l2 c thereof. The other legs l2 b which have not been severed and the heads l2 c will serve as hooks 26 on the loop sheet l0 for engagement with piles (not shown) on a loop tape of a hook-and-loop fastener. The upper movable blade l9 is driven to move its comb teeth from the position of Figure 4B to the position of Figure 4A preparatory to the next loop cutting. The loop sheet l0, as it is further advanced, turns around the downwardly sloping corner guide surface l6, during which time the severed leg l2 a and the hook 26 of each loop l2 are guidedly received in adjacent two of the guide grooves 24 in the stationary blade l8, as shown in Figure 5. When the severed loop l2 are arrived at the outlets of the respective guide grooves 24 where the stationary comb teeth 22 are formed, the lower movable blade 20 is driven to shift its comb teeth 33 rightward from the position of Figure 6A to the position of Figure 6B with the result that the severed leg l2 a of each loop l2 is further cut at the second cutting point 34 (Figure 3) near the foundation fabric ll while the leg l2 a is still held stable in the guide groove 24. At this time, the cut debris 29 (Figure l) are temporarily stored in the channel 28 and then they are discharged from the channel 28 outside the loop cutter l7. The lower movable blade 20 is driven to move its comb teeth 33 from the position of Figure 6B to the position of Figure 6A preparatory to the next loop cutting. The rate of advance of the loop sheet l0 is so synchronized with the reciprocation of the movable blades l9, 20 so that the movable blades l9, 20 made one reciprocation between the positons shown respectively in Figures 4A and 6A and the positions shown respectively in Figures 4B and 4B, each time a loop l2 reaches the cutting zone.

Claims: 1. A method of producing hooks on hook-and-loop fasteners, characterized by: (a) introducing a plurality of parallel spaced first stationary cutting comb teeth (22) of a stationary blade (l8) into loops (l2) projecting from a foundation fabric (ll) of a loop sheet (l0) as the loop sheet (l0) is fed along a path; (b) cutting the loops (l2) from the outside thereof on their one legs (l2a) at a first point (3l) near heads (l2c) of the respective loops (l2) by reciprocating a plurality of parallel spaced first movable cutting comb teeth (30) of a first movable blade (l9) in a direction perpendicular to the axes of the comb teeth (22, 30) while the loops (l2) are guided along the first stationary cutting comb teeth (22), thereby producing a hook (26) from each loop (l2) thus severed; (c) guiding the severed leg (l2a) and the hook (26) of each severed loop (l2) to move in and along an adjacent pair of parallel spaced guide grooves (24) defined in the stationary blade (l8); and (d) further cutting the severed leg (l2a) from the outside of each severed loop (l2) at a second point (34) near the foundation fabric (ll) by reciprocating a plurality of parallel spaced second movable cutting comb teeth (33) of a second movable blade (20) in a direction perpendicular to the axes of a plurality of second stationary cutting comb teeth (27) of the stationary blade (l8) while the severed leg (l2a) is held in one of the two adjacent guide grooves (24). 2. A method according to claim l, said second stationary cutting comb teeth (27) being provided at outlets of the guide grooves (24). 3. An apparatus for producing hooks on hook-and-loop fasteners, comprising a sheet guide (l4) defining thereon a horizontal first passage (l5) and a downwardly inclined second passage (l6) for guiding along said first and second passages (l5, l6) a loop sheet (l0) having a plurality of loops (l2) arranged in transverse rows and longitudinal tiers and each having a pair of legs (l2a, l2b) interconnected by a head (l2c), and a loop cutter (l7) disposed adjacent to said sheet guide (l4) for cutting the loops (l2) twice on their one legs (l2a) at two different points (3l, 34) as the loop sheet (l0) is advanced along said first and second passages (l5, l6), characterized in that said loop cutter (l7) includes (i) a stationary blade (l8) having a plurality of parallel spaced first stationary cutting comb teeth (22) extending in overhanging relation to said first guide path (l5) for being inserted in the loops (l2) in said tiers, a plurality of parallel spaced guide grooves (24) extending downwardly from said first stationary cutting comb teeth (22) along said second second passage (l6) and facing toward said second passage (l6) for receiving the loops (l2) after their first severance, and a plurality of second stationary cutting comb teeth (27) defined at lower ends of said guide grooves (24); (ii) a first reciprocably movable blade (l9) slidably mounted on said stationary blade (l8) and having a plurality of parallel spaced first movable cutting comb teeth (30) disposed above alternate ones of said first stationary cutting comb teeth (22) for cutting the loops (l2) from the outside thereof on their one legs (l2a) at a first point (3l) near the heads (l2c) of the respective loops (l2) while the loops (l2) are guided along the remaining first stationary cutting comb teeth (22), and (iii) a second reciprocably movable blade (20) slidably mounted on said stationary blade (l8) and having a plurality of parallel spaced second movable cutting comb teeth (33) disposed below alternate ones of said second stationary cutting comb teeth (27) for further cutting the severed legs (l2a) from the outside of the severed loops (l2) at a second point (34) near the foundation fabric (ll) while the severed legs (l2a) are held in alternate ones of said guide grooves (24). 4. An apparatus according to claim 3, said loop cutter (l7) being vertically and horizontally movable with respect to said sheet guide (l4) for adjusting said first and second cutting points (3l, 34) on the loops (l2). 5. An apparatus according to claim 3 or 4, said stationary blade (l8) further having an elongate channel (28) disposed adjacent to said second stationary cutting comb teeth (27) and extending transversely across said guide grooves (24) for discharging cut debris (29) therefrom outside said loop cutter (l7). 6. An apparatus according to one of the claims 3 to 5, said first stationary cutting comb teeth (22) having a uniform cross-sectional shape throughout the length thereof. 7. An apparatus according to one of the claims 3 to 6,said first stationary cutting comb teeth (22) defining therebetween a plurality of slots (23) opening toward said sheet guide (l4), said guide grooves (24) extending contiguously from closed ends of the respective slots (23). 8. An apparatus according to one of the claims 3 to 7,said sheet guide (l4) having a horizontal first guide surface (l5) defining said first passage, and a downwardly sloping second guide surface (l6) extending contiguously from said first guide surface (l5) and defining said second passage. 9. An apparatus according to claim 8, said second guide surface (l6) comprising a flat surface. l0. An apparatus according to one of the claims 3 to 9,said said first and second movable cutting comb teeth (30, 33) being tapered. 11. An apparatus according to one of the claims 3 to l0,said sheet guide (l4) having a downwardly sloping guide surface (l6) defining said second passage, said stationary balde (l8) including a bevelled surface (25) extending parallel to said guide surface (l6), said guide grooves (24) being defined in said bevelled surface (25).

Inventors: MURASAKI, RYUICHI
Applicants: YOSHIDA KOGYO K.K.
Application year: 1986
Main classification: A44B18
IPC codes: D06C13, A44B18