In a machine for the production of filter bags for an infusion beverage, wherein a piece of filter paper is folded and filled with an infusion substance, closed to form a filter bag and the filter bag is provided with a string and a tag utilizing a rotary head provided with arms having respective pincers which carry said bag along a path, the improvement which comprises:
- a supply of a strip of paper adapted to form envelopes for said bags, said strip being fed in a direction toward said head;
- a fixed drawing device downstream of said supply and provided with a pair of juxtaposed vertical elements folding said strip into a V section with flanks of different lengths;
- a pair of counter-rotating rollers between which said strip of V-section passes downstream of said elements and provided with means for impressing a longer one of said flanks adjacent to a longitudinal end of the shorter flank as a prefolding line;
- braking means acting upon outer faces of said flanks for resisting displacement of said strip and located downstream of said counter-rotating rollers;
- pulling means engaging said strip downstream of said braking means in said direction for intermittently advancing said strip between said elements, said rollers and said braking means;
- cutting means downstream of said pulling means in said direction for severing from said strip successive wedges of paper folded in a V section and of a length sufficient to receive a respective one of said bags;
- first pincer means swingable in a plane of said arms in one position of said arms on rotation of said head and receiving each wedge;
- and
- second pincer means juxtaposed with the pincer of each arm at said position and including an inner pincer formed with fingers adapted to engage a filter bag on one of said arms in said position, and an outer pincer having fingers juxtaposed with the fingers of said inner pincer, said second pincer means being reciprocatable toward and away from said arm at said position whereby:
- upon advance of said second pincer means toward an arm at said position, said fingers of said inner pincer engage a bag carried by said arm at said position;
- upon movement of said inner pincer means away from said arm at said position, said first pincer means swings a respective wedge between said second pincer means and said arm at said position to receive a filter bag gripped between the fingers of said inner pincer,
- said fingers of said outer pincer engage the respective flanks of the wedge receiving the filter bag in said inner pincer against the fingers of said pincer, and
- upon swinging of said first pincer means from between said second pincer means and said arm at said position, said second pincer means advances toward said arm at said position to insert the wedge and the filter bag received therein in the pincer of the arm at said position.