Molded surface fastener

Abstract: A molded surface fastener comprising: first and second engaging parts (10, 20) each including a flat hook bed (11, 21) having on its surface a multiplicity of rows of hooks (12, 22) molded integrally on the hook bed (11, 21); each hook (12, 22) including a raised portion (SP) and a hook-shape engaging portion (FP) extending forwardly from a distal end of the raised portion (SP), the raised portion (SP) having an inclined back surface (bs) smoothly curving upwardly from the hook bed (11, 21) and a vertical front surface (fs), each hook (12, 22) having a varying cross-sectional area increasing gradually from a distal end of the hook-shape engaging portion (FP) to the base (ba) of the raised portion (SP); and the hooks (12) of the first engaging part (10) and the hooks (22) of the second engaging part (20) being arranged in opposite directions, the row direction pitch of the hooks (12, 22) of one of the first and second engaging parts (10, 20) being twice that of the hooks (22, 12) of the other engaging part (20, 10).

Description: The present invention relates to a molded surface fastener comprising: first and second engaging parts each including a flat hook bed having on its surface a multiplicity of rows of hooks molded integrally on said flat hook bed; each of said hooks including a raised portion and a hook-shape engaging portion extending forwardly from a distal end of said raised portion, said raised portion having a vertical front surface, and said hooks of said first engaging part and said hooks of said second engaging part being arranged mutually in opposite directions. A molded surface fastener of this type is disclosed in EP-A-0 421 295. In this conventional molded surface fastener the row direction pitch of the hooks of the first and second engaging parts is equal and each of said hooks has a uniform cross-sectional area in the hook-shape engaging portion and in the raised portion, said raised portion having a vertical back surface. The problems of this conventional surface fastener having hooks arranged in rows at a regular pitch are: 1. At the time of engagement, since the movement in row direction of each hook is restricted by mating hooks, a strong pressing force would be required to engage them together. 2. At the time of disengagement, the engaged hooks are in a "locked" state which makes the hooks hard to get disengaged. Therefore, undue force is exerted onto the hooks to damage them. EP-A-0 464 754 discloses a surface fastener comprising a first molded engaging part including a flat hook bed having on its surface a multiplicity of rows of hooks molded integrally on said flat hook bed; each of said hooks including a raised portion and a hook-shape engaging portion extending forwardly from a distal end of said raised portion, said raised portion having an inclined back surface smoothly curving upwardly from said hook bed and a vertical front surface, each of said hooks having a varying cross sectional area increasing gradually from a distal end of said hook-shape engaging portion to a base of said raised portion. The hooks of said first engaging part are arranged in two or more sections, and said hook elements in one section and those in sections adjacent thereto face directions perpendicular to one another contrary to the molded surface fastener of the type mentioned above. The second engaging part of this conventional surface fastener is not identical with the first engaging part but includes a pile-like surface fastener member. It is an object of the invention to provide a surface fastener of the type mentioned above well situated to industrial materials applications which retains its shape and a high degree of engaging strenth even after repeated use. According to the invention a surface fastener satisfying this requirement is characterized in that each of said hooks has a varying cross-sectional area increasing gradually from a distal end of said hook-shape engaging portion to a base of said raised portion; said raised portion having an inclined back surface smoothly curving upwardly from said hook bed; and that the row direction pitch of said hooks of one of said first and second engaging parts is twice the row direction pitch of said hooks of the other engaging part. Since the hooks on one engaging part are arranged in row direction with a pitch twice as wide as that of the other engaging part, there is a space between two sets of engaged hooks. Therefore the movement in row direction of hooks is not restricted at the time of engagement and disengagement. Accordingly, no undue pressing force nor disengaging force is exerted onto the hooks so that engaging/disengaging operation can be performed smoothly and the hooks are not damaged. Alternatively, the hooks of adjacent rows of each of the first and second engaging parts may be arranged mutually in opposite directions. Further, the hooks of adjacent rows of each of the first and second engaging parts may be arranged mutually in a staggered manner. The hooks which make up the engaging parts in this invention are of the shape described above. Also, the interhook spacing along the row direction of one of either the first or second engaging parts is twice that of the interhook spacing along the row direction of the other engaging part. Moreover, the hooks in the hook rows for the first and second engaging parts face in opposite directions. This means that not only can both engaging parts engage with each other smoothly at their moment of engagement, but also, the front ends of the hooks in one of the engaging parts will make contact with the front ends of the hooks in the other engaging parts at the same time as the back sides of the hooks neighboring the aforementioned hooks for one of the engaging parts make contact with the backsides of the corresponding aforementioned hooks for the other engaging part, so that the engaging parts smoothly engage with each other. The corresponding hooks for each adjacent hook row for the first and second engaging parts face in opposing directions. In addition, each of the hooks for each neighboring hook row for these first and second engaging parts are arranged in a staggered manner, so the hooks are not only held securely in the row direction but are also sufficiently held in the lateral direction. Moreover, even when separating the first and second engaging parts, if a force in excess of the necessary separation force is applied to both of the engaging parts in the direction of separation, the front ends of the mutually interlocked hook shaped engaging portions will be slightly twisted, and the engaging parts can thus be easily separated. BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a fragmentary side view of a typical embodiment of a molded surface fastener for this invention, showing the surface fastener at the time of initial insertion of hooks; FIG. 2 is a fragmentary side view of the surface fastener midway through the insertion process; FIG. 3 is a fragmentary side view of the surface fastener in its engaged state; FIG. 4 is a plan view of an example arrangement of the hooks for the surface fastener; and FIGS. 5(a) and 5(b) are cross-sectional views taken along lines I-I and II-II, respectively, of FIG. 4. DETAILED DESCRIPTION The following is a detailed description of the present invention based on a preferred embodiment shown in the accompanying drawings. FIGS. 1 to 3 are views of a molded surface fastener for a typical embodiment of the invention in various states of engagement. FIG. 4 is a plan view of an example engaging row arrangement for the same surface fastener. FIGS. 5(a) and 5(b) are cross-sectional views taken along lines I-I and II-II, respectively, of FIG. 4. As shown in FIGS. 1 to 3, the surface fastener in this invention is a single body type molded from synthetic resin consisting of first and second engaging layers 10, 20, each of which has a large number of hooks 12, 22 having the same shape projecting vertically at fixed intervals from their corresponding hook beds 11 and 21. The arrangement of this large number of rows of hooks 22 is shown in FIG. 4. Each individual hook 12, 22 shown in FIGS. 1 to 3 for this invention has the following kind of shape with regard to the hook beds 11, 21; it includes a raised portion (SP) having an inclined back surface (bs) which smoothly curves upwards from the hook beds 11, 21 and a vertical front surface (fs) and a rib (r) formed on either side of raised portion (SP), and a hook shaped engaging portion (FP) extending forward from the front end of the raised portion (SP). The cross-sectional area of the hook 12, 22 gradually increases when going from the front end of the hook shaped engaging portion (FP) to the base (ba) of the raised portion (SP), eventually reaching a maximum value at this base. Although there is a rib (r) described in the above, this is not actually essential in this invention. Now, the construction of the surface fastener in this invention is such that the row spacing for the hooks 12 for the first engaging part 10 and the spacing of the hooks 22 for the second engaging part 20 is different. Accordingly, in the example shown in the diagrams, the spacing of the hooks 12 for the first engaging part 10 is taken to be (p), and the spacing for the hooks 22 for the second engaging part 20 is taken to be 1/2 (p). This is to say that the spacing of the hooks 12 for the first engaging part 10 is twice that of the hooks 22 for the second engaging part 20. Also, the hooks 12 for the first engaging part 10 and the hooks 22 for the second engaging part 20 are arranged mutually in opposite directions. It can be seen from FIGS. 4 and 5 that the corresponding hooks 12, 22 belonging to reciprocally neighboring hook rows A and B for the first and second engaging parts 10 and 20 are arranged in opposite directions and, as again becomes clear from FIGS. 4 and 5, are staggered with respect to each other. The hook 12, 22 for the surface fastener in this invention is of a shape which closely resembles that of an ocean wave top just before breaking, as is described above. In addition, the spacing of the hooks 12 for the first engaging part 10 is twice that of the hooks 22 for the second engaging part 20, with the hooks for these two engaging parts facing in opposite directions. This means that when the fastener is engaged, not only can the hook 12 for the first engaging part 10 be inserted smoothly between the two hooks 22 for the second engaging part 20 but also, as is shown in FIGS. 1 to 3, the front end of the hook shaped engaging portion (FP) of the hook 12 projecting from the first engaging part 10 makes contact with the front end of the hook shaped engaging portion (FP) of the hook 22 for the second engaging part 20. At the same time, the back surface (bs) of the hook 22 which is next to the aforementioned hook 22 on the second engaging part 20 and the back surface (bs) of the same hook 12 for the first engaging part 10 make contact and the hook is guided smoothly into position in the sequence shown in FIGS. 2 and 3. The corresponding hooks 12, 22 for each adjacent hook row A and B for the first and second engaging parts 10, 20 face in opposing directions, as is shown in FIG. 5. The hooks 22 in each of the neighboring hook rows A, B for the second engaging part 20 are staggered. In addition, in the case where the hooks 12 in each of the neighboring hook rows A, B for the first engaging part 10 are also staggered, the hooks are not only held securely in the row direction but are held firmly in the lateral direction. Moreover, even when separating the first and second engaging parts 10, 20, if a force in excess of the necessary separation force is applied to both of the engaging parts 10, 20 in the direction of separation, the front ends of the mutually interlocked hook shaped engaging portions (FP) will be slightly twisted, and the engaging parts can thus be easily separated. As becomes clear from the above description, according to the surface fastener of this invention, partly since either of the pair of engaging parts is in the form of a single molded body and partly since the pair of engaging parts make hook-to-hook coupling, it would provide sufficient coupling strength free from accidental separation. Also, these hooks have a specific cross-sectional wave-like shape although this is not shown. At the same time, the hooks for the first and second engaging parts face in opposite directions so that the coupling of the elements can take place very smoothly without any damage. It follows that the molded surface fastener according to this invention has a much wider range of application than that of conventional surface fasteners. This invention would therefore be particularly suited to a wide range of fields of applications with regards to industrial materials, where a high degree of performance is necessary.

Claims: A molded surface fastener comprising: first and second engaging parts (10, 20) each including a flat hook bed (11, 21) having on its surface a multiplicity of rows of hooks (12, 22) molded integrally on said flat hook bed (11, 21); each of said hooks (12, 22) including a raised portion (SP) and a hook-shape engaging portion (FP) extending forwardly from a distal end of said raised portion (SP), said raised portion (SP) having a vertical front surface (fs); and said hooks (12) of said first engaging part (10) and said hooks (22) of said second engaging part (20) being arranged mutually in opposite directions; characterized in that each of said hooks (12, 22) has a varying cross-sectional area increasing gradually from a distal end of said hook-shape engaging portion (FP) to a base (ba) of said raised portion (SP); said raised portion (SP) having an inclined back surface (bs) smoothly curving upwardly from said hook bed (11, 21); and that the row direction pitch of said hooks (12, 22) of one of said first and second engaging parts (10, 20) is twice the row direction pitch of said hooks (22, 12) of the other engaging part (20, 10). A molded surface fastener according to claim 1, wherein a rib (r) is formed on one or either side of said base (ba) of said raised portion (SP). A molded surface fastener according to claim 1, wherein said hooks (12, 22) of adjacent rows (A, B) of each of said first and second engaging parts (10, 20) are arranged mutually in opposite directions. A molded surface fastener according to claim 1 or 2, wherein said hooks (12, 22) of adjacent rows (A, B) of each of said first and second engaging parts (10, 20) are arranged mutually in a staggered manner.

Inventors: MURASAKI RYUICHI, MURASAKI, RYUICHI
Applicants: YKK CORP, YKK CORPORATION
Application year: 1993
Main classification: A44B18
IPC codes: A44B18