Abstract A method of and device for detecting surface elevations, like lumps, wrinkles, creases, etc. in paper and other sheet material. The sheet material is made to pass over a supporting roll and feeler members are mounted in a movable manner at a small distance from the sheet material above the supporting roll. This distance is smaller than the surface elevations to be detected and electronic means are provided to give a signal when a surface elevation lifts the feeler member, thereby changing the distance between the feeler member and an independently pivoted reference member. Means are provided to keep the distance between the surface of the sheet material and the feeler members constant, independent of inaccuracies and eccentric running of the supporting roll by providing contact members which take bearing on the supporting roll either via the sheet material or on two smaller diameter end portions of the supporting roll. By tuning the mechanical oscillatory frequency of feeler members and reference members the device can be made insensitive to vibrations of the supporting roll.
Device for detecting surface elevations in sheet material moving over a supporting roll (42) which has a supporting surface of cylindrical shape comprising at least one feeler member adapted to be mounted in a movable manner opposite the area in which the sheet material is in contact with the supporting surface, at a distance, which is smaller than the smallest surface elevation to be detected, which distance may be zero, from the surface of the sheet material, the feeler member (1) being adapted to contact the surface elevations to be detected, at least one contact member (3) mounted in a movable manner adapted to take a bearing on the supporting roll, a reference member (33), the position of which relative to the surface of the sheet material is controlled by the contact member (3), adjustable means (41) being provided, controlled by the contact member (3), which prevents the distance between the reference member (33) and the surface of the sheet material becoming less than a pre-set value, and adjustable means (32) being provided which prevent the distance between the reference member (33) and the feeler member (1) becoming more than a pre-set value, and electrical means adapted to produce and electrical signal when the feeler member (1) is moved relative to the reference member (33) by a surface elevation in the sheet material.
Claim 2
Dependent Claim
223 words
Device for detecting surface elevations in sheet material moving over a supporting roll (42) which has a supporting surface of cylindrical shape comprising at least one feeler member adapted to be mounted in a movable manner opposite the area in which the sheet material is in contact with the supporting surface, at a distance, which is smaller than the smallest surface elevation to be detected, which distance may be zero, from the surface of the sheet material, the feeler member (1) being adapted to contact the surface elevations to be detected, at least one contact member (3) mounted in a movable manner adapted to take a bearing on the supporting roll, a reference member (33), the position of which relative to the surface of the sheet material is controlled by the contact member (3), adjustable means (41) being provided, controlled by the contact member (3), which prevents the distance between the reference member (33) and the surface of the sheet material becoming less than a pre-set value, and adjustable means (32) being provided which prevent the distance between the reference member (33) and the feeler member (1) becoming more than a pre-set value, and electrical means adapted to produce and electrical signal when the feeler member (1) is moved relative to the reference member (33) by a surface elevation in the sheet material.