Web threading system

Apparatus for directing the tail of a web of flexible material to a predetermined location comprising:

• a first wall element having a surface open to the atmosphere and defining a path of movement for said web tail and having a terminal end adapted to be directed toward said predetermined location;
• means defining a restricted opening communicating with said path of movement including a foil element having a substantially smoothly curved fluid flow attachment surface leading from said restricted opening toward said first wall element terminal end whereby gas under pressure passing through said restricted opening will attach itself to said fluid flow attachment surface due to the Coanda effect and entrain ambient air and said web tail to direct said web tail to said predetermined location;
• additional wall elements fixedly positioned along the edges of said first wall element in the direction of said path of movement to form a channel member defining an interior open to the atmosphere adapted to receive said web tail therein;
• and a handle attached to said channel member, said handle defining a flow path for pressurized gas which is in fluid-flow communication with said channel member interior through said restricted opening.

Apparatus for directing the tail of a web of flexible material to a predetermined location comprising:

• a first wall element having a surface open to the atmosphere and defining a path of movement for said web tail and having a terminal end adapted to be directed toward said predetermined location;
• means defining a restricted opening communicating with said path of movement including a foil element having a substantially smoothly curved fluid flow attachment surface leading from said restricted opening toward said first wall element terminal end whereby gas under pressure passing through said restricted opening will attach itself to said fluid flow attachment surface due to the Coanda effect and entrain ambient air and said web tail to direct said web tail to said predetermined location;
• additional wall elements fixedly positioned along the edges of said first wall element in the direction of said path of movement to form a channel member defining an interior open to the atmosphere adapted to receive said web tail therein;
• and means for selectively increasing the operational length of said channel member.

In combination:

• first mechanical means having a web contact surface for delivering a web of flexible material at a predetermined web velocity;
• second mechanical means having a web contact surface for receiving said web of flexible material and spaced from said first mechanical means, said first and second mechanical means normally cooperating to transport said web of flexible material therebetween along a predetermined first path of web movement;
• and
• apparatus disposed between said first and second mechanical means and spaced from said first path of web movement for receiving the tail of the web from said first mechanical means and delivering said tail to the second mechanical means, said apparatus comprising at least one apparatus segment including an elongated first wall element having a web entry end and a web exit end and defining a second path of web movement differing from said first path of web movement and adjacent thereto, means defining a restricted opening communicating with said second path of web movement located at the first wall element web entry end and including a foil element having a substantially smoothly curved fluid flow attachment surface leading from said restricted opening toward the first wall element whereby gas under pressure passing through said first restricted opening will attach itself to said foil element fluid flow attachment surface due to the Coanda effect and entrain ambient air to provide a gaseous flow along said first wall element toward the web exit end thereof at a velocity exceeding the predetermined web velocity so that said web tail is entrained along said first wall element by the gaseous flow and delivered thereby to said second mechanical means, said web contact surface of said second mechanical means adapted to move faster than the web contact surface of the first mechanical means whereby the web will be drawn taut when the tail thereof is engaged by said second mechanical means causing the web to withdraw itself from the second path of web movement and move along said first path of web movement, said first wall element being unobstructed and open to the atmosphere so as not to impede such web withdrawal.

A method of directing a continuously moving web of flexible material having a tail to a predetermined first path of movement extending between spaced first and second mechanical means comprising the steps of:

• positioning means defining a flow path for gas between said first and second mechanical means adjacent to said first path of web movement and along a second path of web movement;
• flowing a pressurized gas through a restricted opening communicating with said gas flow path in a direction differing from the direction of said gas flow path;
• changing the direction of the pressurized gas after it passes through said restricted opening through utilization of the Coanda effect so that a gaseous flow is established along the gas flow path at a velocity exceeding the velocity of the web and toward the second mechanical means;
• bringing the web tail into engagement with the gaseous flow after the web tail has been delivered by the first mechanical means so that the web tail is entrained and propelled along said second path of web movement toward said first mechanical means;
• and
• pulling the web taut after it engages the second mechanical means so that the web moves from said second path of web movement to said first path of web movement.