Filter medium forming system and process

A filter medium forming system for preparing a pleated filter medium having a plurality of pleats, the plurality of pleats defining adjacent pair of first and second pleats, each pleat having first and second sides which are integrally connected through a first linear depression with each other to form an upwardly-pointing pleat portion, the second side of the first pleat and the first side of the second pleat being integrally connected through a second linear depression with each other to form a downwardly-pointing pleat portion, each pleat side having oppositely located first and second edge sections which have first and second edges, respectively, which extend substantially perpendicular to each linear depression, the first edge sections of the first and second sides of each pleat being approached and bonded to each other to form a plurality of first bonded sections, the second edge section of the first pleat second side and the second edge section of the second pleat first side, of the adjacent pairs of first and second pleats, being approached and bonded to each other to form a plurality of second bonded sections,

• said filter medium forming system comprising means for forming the first and second linear depressions, means for applying adhesive on the first and second edge sections of the first and second sides, means for pleating the filter medium along the first and second linear depressions, and means for tightly contacting the edge sections of the first and second pleat sides to bond the edge sections.

A filter medium forming process comprising the following steps in the sequence set forth:

• forming linear depressions on opposite side surfaces of an elongate sheet-type filter medium;
• applying adhesive onto the opposite side surfaces of the filter medium at edge sections;
• pleating the filter medium along the linear depressions to form a pleated filter medium having a plurality of pleats, each pleat having two sides which are contiguous through the linear depression;
• and
• tightly contacting predetermined sections of the sides of each pleat to bond said predetermined sections with each other with adhesive.

A filter medium forming process for preparing a pleated filter medium having a plurality of pleats, the plurality of pleats defining adjacent pair of first and second pleats, each pleat having first and second sides which are integrally connected through a first linear depression with each other to form an upwardly-pointing pleat portion, the second side of the first pleat and the first side of the second pleat being integrally connected through a second linear depression with each other to form a downwardly-pointing pleat portion, each pleat side having oppositely located first and second edge sections which have first and second edges, respectively, which extend substantially perpendicular to each linear depression, the first edge sections of the first and second sides of each pleat being approached and bonded to each other to form a plurality of first bonded sections, the second edge section of the first pleat second side and the second edge section of the second pleat first side, of the adjacent pairs of first and second pleats, being approaches and bonded to each other to form a plurality of second bonded sections,

• said filter medium forming process comprising the steps, in the sequence as set forth, of forming the first and second linear depressions, applying adhesive onto the first and second edge sections of the first and second edge sections of the first and second sides, pleating the filter medium along the first and second liner depressions, and tightly contacting the edge sections of the first and second pleat sides to bond the edge sections.

A filter medium forming system comprising:

• means for forming linear depressions on opposite side surfaces of an elongate sheet-type filter medium;
• means for applying adhesive onto the opposite side surfaces of the filter medium at edge sections;
• means for pleating the filter medium along the linear depressions to form a pleated filter medium having a plurality of pleats, each pleat having two sides which are contiguous through each linear depression;
• and
• means for tightly contacting predetermined sections of the sides of each pleat to bond said predetermined sections with each other with the adhesive, said tightly contacting means including first and second screw drums whose axes are parallel with each other, the pleats at a first edge section engaging with thread ridges of said first screw drum, the pleats at a second edge section engaging with thread ridges of said second screw drum, each screw drum having a first section having thread ridges whose pitch decreases in the advancing direction of said filter medium.