Web alignment apparatus for multi-level web material

In a web alignment apparatus for use with tufted webs and the like having a backing and a pile on the backing inwardly of the edge of the latter, pile edge sensing means for producing a pneumatic signal that varies in amplitude with the deviation of the pile edge from a preselected lateral position, and power means responsive to said pneumatic signal for relatively moving the web and a device that operates on the web to maintain the pile edge in a preselected lateral position relative to the device which operates on the web, the improvement comprising the pile edge sensing apparatus including a gap-type pneumatic sensor having a sensing orifice at one side of a gap and a transmitting orifice at the other side of the gap for transmitting a stream of air toward the sensing orifice and a vane extending into the gap to variably interrupt the stream from the transmitting orifice and thereby vary the pneumatic signal at the sensing orifice, a web engaging member adapted to engage the pile edge at a sensing location, a first support arm extending transverse to the plane of the web, a second arm extending transverse to the first arm, means mounting the second arm on a support for movement relative thereto about a second pivot axis that extends generally parallel to the pile edge of the web and having a preselected position relative to the sensing location, means pivotally mounting the first arm on the second arm for pivotal movement relative to the second arm about a first pivot axis that extends generally parallel to the pile edge of the web at the sensing location, means mounting said web engaging member on said first arm to effect swinging of said first arm about said first pivot axis relative to said second arm in response to movement in a path generally paralleling the plane of the web and laterally of the pile edge, said web engaging member being operative in response to movement thereof in a second path transverse to the plane of the web to move said first arm in a direction transverse to the plane of the web and thereby pivot said second arm about said second pivot axis relative to said support, means mounting said vane on said first arm for movement therewith, said vane being constructed and arranged with relation to said gap-type pneumatic sensor to vary the pneumatic signal at said sensing orifice in response to movement of said web engaging member along either said first or said second path.

In an apparatus for operating on a traveling multi-level web of the type having a first lengthwise extending face portion disposed at one level and a second lengthwise extending face portion projecting above the first level and defining a step between the first and second face portions, a control system including sensing means at a sensing location for sensing the step between the first and second face portions and power means actuated by the sensing means for relatively shifting the web and the apparatus that operates on the web in a direction crosswise of the course of web travel to maintain the step in the web in a preselected lateral position relative to apparatus that operates on the web, the improvement comprising:

• said sensing apparatus including a gap-type pneumatic sensor having a sensing orifice at one side of the gap and a transmitting orifice at the other side of the gap for directing a stream of air toward the sensing orifice, vane means extending into the gap to variably interrupt the stream of air and thereby vary the pneumatic signal at the sensing orifice, a web engaging member adapted to engage the step in the web, means mounting said web engaging member for movement along a first path crosswise of the course of travel of the web at the sensing location and generally parallel to the plane of the web to sense lateral deviations of the course of travel of the step from said preselected lateral position and in a second path generally transverse to the plane of the web at said sensing location to sense when the web engaging member rides onto said second face portion, means operatively connecting said web engaging member to said vane means for moving the latter in the gap to variably interrupt the stream of air from the transmitting orifice in response to movement of the web engaging member along either said first or said second path, said power means including means responsive to the fluid pressure conditions at said sensing orifice for relatively shifting the web and the apparatus which operates thereon in a direction to correct lateral deviation of the position of the step relative to the apparatus which operates on the web.