Surface Fastener and Molding Device

Abstract

A surface fastener includes a base part and a plurality of engaging elements formed integrally with the base part. A lower half part of the stem portion has a first shape in which an outer surface is formed straightly or substantially straightly on viewing the engagement element from the machining direction, and the lower half part has a second shape including a part where an outer surface is curved toward the surface of the base part on viewing engagement element from the cross direction. Thus, the surface fastener has a structure and/or characteristic that is different between the machining direction and the cross direction.

1 . A surface fastener made of synthetic resin and including a base part and a plurality of engaging elements-formed integrally with the base part, the engaging elements each including a stem portion and an engaging head, the stem portion projecting from a surface of the base part in a thickness direction of the base part, the engaging head being formed at a distal end part of the stem portion, a section of at least an upper end part of the stem portion orthogonally to the thickness direction having a circular or nearly circular shape, the engaging head having a shape which spreads overall from the distal end part of the stem portion in a direction orthogonal to the thickness direction, wherein:
 a lower half part of the stem portion includes a part where an outer surface is formed straightly or substantially straightly in a first shape obtained by viewing the engagement element from the machining direction, the outer surface facing a cross direction orthogonal to the machining direction, and the lower half part includes a part where an outer surface facing the machining direction is curved toward the surface of the base part in a second shape obtained by viewing engagement element from the cross direction, the outer surface. 
 
     
     
         2 . The surface fastener according to  claim 1 , wherein:
 an upper half part of the stem portion in the second shape includes a part where the outer surface facing the machining direction is formed straightly or substantially straightly, and   the part of the second shape where the outer surface is formed straightly or substantially straightly is provided in an area shorter than the part of the first shape where the outer surface is formed straightly or substantially straightly.   
     
     
         3 . A surface fastener made of synthetic resin and including a base part and a plurality of engaging elements formed integrally with the base part, the engaging elements each including a stem portion and an engaging head, the stem portion projecting from a surface of the base part in a thickness direction of the base part, the engaging head being formed at a distal end part of the stem portion, a section of at least an upper end part of the stem portion orthogonally to the thickness direction having a circular or nearly circular shape, the engaging head having a shape which spreads overall from the distal end part of the stem portion in a direction orthogonal to the thickness direction, wherein:
 when, in the engaging element seen from the machining direction, a length of a joint part of the stem portion jointing to the base part in a cross direction orthogonal to the machining direction is defined as a first dimension; and, in the engaging element seen from the cross direction, a length of the joint part in the machining direction is defined as a second dimension, the stem portion has a shape such that the second dimension is greater than the first dimension, and   when peel strengths of the surface fastener in the case that the surface fastener and a loop member that are in engagement with each other are peeled from each other in the machining direction and in the cross direction are respectively defined as MD peel strength and CD peel strength, the stem portion has a shape such that the CD peel strength is greater than the MD peel strength.   
     
     
         4 . A surface fastener made of synthetic resin and including a base part and a plurality of engaging elements formed integrally with the base part, the engaging elements each including a stem portion and an engaging head, the stem portion projecting from a surface of the base part in a thickness direction of the base part, the engaging head being formed at a distal end part of the stem portion, a section of at least an upper end part of the stem portion orthogonally to the thickness direction having a circular or nearly circular shape, the engaging head having a shape which spreads overall from the distal end part of the stem portion in a direction orthogonal to the thickness direction, wherein:
 CD flexibility is higher than MD flexibility, the CD flexibility being exerted when a part of the surface fastener that extends in a cross direction orthogonal to a machining direction is bent in the thickness direction, the MD flexibility being exerted when a part of the surface fastener that extends in the machining direction is bent in the thickness direction.   
     
     
         5 . The surface fastener according to  claim 1 , wherein:
 the plurality of engaging elements are arranged in a line at a regular pitch in the machining direction to form an element row,   a plurality of element rows are arranged at a regular interval in the cross direction,   the engaging elements in each of the element rows are shifted by half the pitch in the machining direction relative to the engaging elements in another one of the element rows that is adjacent in the cross direction, and   in regard to the machining direction, the engaging elements are arranged at positions such that occupied areas occupied by the respective stem portions of the engaging elements include portions that overlap each other between the element rows that are adjacent to each other in the cross direction.   
     
     
         6 . The surface fastener according to  claim 1 , wherein:
 the engaging elements each include at least one pawl portion projecting in the cross direction from an outer peripheral edge part of the engaging head.   
     
     
         7 . A molding device including a die wheel and a feeding nozzle, the die wheel being configured to rotate in one direction, the feeding nozzle being configured to feed molten synthetic resin toward the die wheel, the molding device being used in manufacturing a surface fastener, the surface fastener including a base part provided with a plurality of engaging elements, the engaging elements each including a stem portion and an engaging head, the stem portion projecting from a surface of the base part in a thickness direction of the base part, the engaging head being formed at a distal end part of the stem portion, wherein:
 the die wheel includes at least one circular cylindrical sleeve and a driving roller configured to rotate the sleeve,   the sleeve has a plurality of through-holes penetrating through the sleeve from an outer peripheral surface to the inner peripheral surface of the sleeve,   the plurality of through-holes are arranged in a line at a regular hole pitch in a machining direction to form a hole row,   a plurality of hole rows are arranged at a regular interval in a cross direction that is orthogonal to the machining direction,   the through-holes in each of the hole rows are shifted by half the hole pitch in the machining direction relative to the through-holes in another one of the hole rows that is adjacent in the cross direction, and   in regard to the machining direction, the through-holes are arranged at positions such that occupied areas occupied by the respective through-holes-include portions that overlap each other between the hole rows that are adjacent to each other in the cross direction.   
     
     
         8 . The surface fastener according to  claim 3 , wherein:
 the plurality of engaging elements are arranged in a line at a regular pitch in the machining direction to form an element row,   a plurality of element rows are arranged at a regular interval in the cross direction,   the engaging elements in each of the element rows are shifted by half the pitch in the machining direction relative to the engaging elements in another one of the element rows that is adjacent in the cross direction, and   in regard to the machining direction, the engaging elements are arranged at positions such that occupied areas occupied by the respective stem portions of the engaging elements include portions that overlap each other between the element rows that are adjacent to each other in the cross direction.   
     
     
         9 . The surface fastener according to  claim 4 , wherein:
 the plurality of engaging elements are arranged in a line at a regular pitch in the machining direction to form an element row,   a plurality of element rows are arranged at a regular interval in the cross direction,   the engaging elements in each of the element rows are shifted by half the pitch in the machining direction relative to the engaging elements in another one of the element rows that is adjacent in the cross direction, and   in regard to the machining direction, the engaging elements are arranged at positions such that occupied areas occupied by the respective stem portions of the engaging elements include portions that overlap each other between the element rows that are adjacent to each other in the cross direction.   
     
     
         10 . The surface fastener according to  claim 3 , wherein:
 the engaging elements each include at least one pawl portion projecting in the cross direction from an outer peripheral edge part of the engaging head.   
     
     
         11 . The surface fastener according to  claim 4 , wherein:
 the engaging elements each include at least one pawl portion projecting in the cross direction from an outer peripheral edge part of the engaging head.