Machine for forming filter bags for infusion products

A machine for making filter bags for infusion products, each filter bag including a piece of filter material to which is associated a tie thread for connection with a gripping tag;

• the machine for making filter bags comprising:
• a wheel defining a work surface;
• the wheel being rotational about a wheel axis to define a working path having a circular feed direction;
• a first feed station configured for depositing individual tags, in phase, on the work surface in a depositing zone of the working path;
• a second feed station configured for feeding, along a weave path, a thread on the work surface, starting from a further zone downstream of the depositing zone with reference to the feed direction of the wheel;
• a third feed station configured for feeding a continuous strip of filter material on the work surface superposing the weave of thread and the tag, and positioned downstream relative to the second feed station with reference to the feed direction of the wheel;
• a sealing device, positioned downstream of the first and second feed stations with reference to the feed direction of the wheel, and configured to provide seals between the thread, the tag and the strip of filter material;
• a first feed device configured for moving the strip of filter material along a feed line, and positioned downstream of the wheel with reference to a feed direction of the strip of filter material;
• a completion station configured for completing the filter bag equipped with the tag and the thread, the completion station positioned downstream of the first feed device with reference to the feed direction of the strip of filter material, and configured for forming the filter bag, for introducing a dose of infusion product in the filter bag formed and for closing the filter bag containing the dose of infusion product, wherein the first feed device comprises two first feed rollers configured for unwinding in a controlled manner, a quantity of the strip of filter material to be placed on the work surface of the wheel, the two first feed rollers being controlled by a control system for adjusting, via a motor, a speed of rotation of the two first feed rollers as a function of a length of the piece of filter material needed to form the filter bag of a desired size, and
• a transfer device configured for transversely moving the strip of filter material being fed, to modify a position of a centerline axis of the strip of filter material, such that the centerline axis coincides with a working line on the work surface of the wheel;
• the working line being parallel to the feed line and defined as a function of the desired size of the filter bag.