Automatic regulation of the position of the lateral edge of a travelling web

In an apparatus for transporting an elongated web along a predetermined path, a regulating system for automatically keeping the position of the lateral edge of the travelling web within preselected first and second tolerance ranges, the regulating system comprising, in combination, sensing means operative for sensing the position of the lateral edge of the travelling web;

• position-correcting means operative when activated for effecting corrective movement of the travelling web in a direction causing the lateral edge thereof to change position;
• and regulating means connected to the sensing means and to the position-correcting means and operative for causing the latter to effect corrective movements of the travelling web at a first speed when the sensed position of the web edge is outside the first tolerance range and at a different second speed when the sensed position of the web edge is outside the preselected second tolerance range, wherein the sensing means comprises a first sensing unit operative for generating first signals indicating that the web edge position has left the first tolerance range and a second sensing unit discrete from the first sensing unit and operative for generating second signals indicating that the web edge position has left the second tolerance range.

In an apparatus for transporting an elongated web along a predetermined path, a regulating system for automatically keeping the position of the lateral edge of the travelling web within preselected first and second tolerance ranges, the regulating system comprising, in combination, sensing means operative for sensing the position of the lateral edge of the travelling web;

• position-correcting means operative when activated for effecting corrective movement of the travelling web in a direction causing the lateral edge thereof to change position;
• and regulating means connected to the sensing means and to the position-correcting means and operative for causing the latter to effect corrective movements of the travelling web at a first speed when the sensed position of the web edge is outside the first tolerance range and at a different speed when the sensed position of the web edge is outside the preselected second tolerance range, wherein the sensing means comprises a single sensing device operative for generating a signal indicative of the position of the lateral edge of the travelling web, the regulating system including means for determining from such signal whether the edge position is outside one of the tolerance ranges.

In an apparatus for transporting an elongated web along a predetermined path, a regulating system for automatically keeping the position of the lateral edge of the travelling web within preselected first and second tolerance ranges, the regulating system comprising, in combination, sensing means operative for sensing the position of the lateral edge of the travelling web;

• position-correcting means operative when activated for effecting corrective movement of the travelling web in a direction causing the lateral edge thereof to change position;
• and regulating means connected to the sensing means and to the position-correcting means and operative for causing the latter to effect corrective movements of the travelling web at a first speed when the sensed position of the web edge is outside the first tolerance range and at a different second speed when the sensed position of the web edge is outside the preselected second tolerance range, wherein the sensing means comprises a single sensing device operative for generating a signal indicative of the position of the lateral edge of the travelling web, the regulating system including means for determining from such signal whether the edge position is outside one tolerance range and means for determining from such signal whether the edge position is outside both tolerance ranges.