Doctor

A doctor blade comprising a doctor blade body:

• a doctor blade edge surface with a doctor blade edge;
• a doctor blade body delimited by a flat surface upper side and a flat surface underside and configured for detachable fastening to a holder and
• a curved blade profile portion extending form the doctor blade edge to the upper side of the doctor blade body, wherein in an unloaded state of the doctor blade, the curved blade profile has, in relation to a Cartesian coordinate system with x-axis of the Cartesian coordinate system coincides with and is parallel to the doctor blade flat surface upper side and the y-axis of the Cartesian coordinate system is perpendicular to the x-axis which intersects a most distal portion of the doctor blade edge, a cuboidal course f(x) wherein the following applies for the course f(x) of the curved blade profile, from the doctor blade edge to the doctor blade upper side, of the doctor blade having an edge surface thickness and a thickness t from the doctor blade upper side to the doctor blade underside:
• f(x)=ax3+bx2+cx+d,
• wherein for a, b, c, d:
• a>0, b>0, c≥0 and d=s−t, or wherein for a, b, c, d:
• a>0, c>0, b<0 and d=s−t and wherein, for the cuboidal course f(x) of the curved blade profile, the following applies for the constants a, b, and c:
• 0.000485≤a≤0.0021953,
• 3.33158≤b≤4.545127, and
• 1.468371≤c≤25.0128.

A doctor blade comprising:

• a doctor blade edge;
• a doctor blade body having a doctor blade upper side and a doctor blade underside;
• and
• a curved blade profile which is formed between the doctor blade edge and the doctor blade body, wherein in an unloaded state of the doctor blade and in relation to a Cartesian coordinate system the curved blade profile has cuboidal course f(x) from the doctor blade edge to the doctor blade body, wherein the x-axis of the Cartesian coordinate system coincides with and is parallel to the doctor blade body upper side the y-axis of the Cartesian coordinate system is perpendicular to the x-axis which intersects a most distal portion of the doctor blade edge, wherein the course f(x) of the curved blade profile, from the doctor blade edge to the doctor blade body, of the doctor blade having a thickness s at the doctor blade edge and a thickness t at the doctor blade body:
• f(x)=ax3+bx2+cx+d,
• and wherein the following applies for the constants a, b, c, d:
• a) a>0, (b and c)≥0 and d=s−t, or
• b) (a and c)>0, b<0 and d=s−t, and wherein, for the cuboidal course f(x) of the curved blade profile, the following applies for the constants a, b, and c:
• 0.00068≤a≤0.00158,
• 3.3321≤b≤4.5416, and
• 10.19478≤c≤10.2501.

A doctor blade comprising a doctor blade body:

• a doctor blade edge surface with a doctor blade edge;
• a doctor blade body delimited by a flat surface upper side and a flat surface underside and configured for detachable fastening to a holder and
• a curved blade profile portion extending form the doctor blade edge to the upper side of the doctor blade body, wherein in an unloaded state of the doctor blade, the curved blade profile has, in relation to a Cartesian coordinate system with x-axis of the Cartesian coordinate system coincides with and is parallel to the doctor blade flat surface upper side and the y-axis of the Cartesian coordinate system is perpendicular to the x-axis which intersects a most distal portion of the doctor blade edge, a cuboidal course f(x) wherein the following applies for the course f(x) of the curved blade profile, from the doctor blade edge to the doctor blade upper side, of the doctor blade having an edge surface thickness and a thickness t from the doctor blade upper side to the doctor blade underside:
• f(x)=ax3+bx2+cx+d,
• wherein for a, b, c, d:
• a>0, b≥0, c≥0 and d=s−t, or
• wherein for a, b, c, d:
• a>0, c>0, b<0 and d=s−t and wherein the following applies for the thickness s of the doctor blade at the doctor blade edge and the thickness t of the doctor blade at the doctor blade upper side:
• 60 μm≤s≤125 μm and
• 150 μm≤t ≤200 μm.