Patent ID: 8677926

Claim:
A solid coating die for applying an insulation varnish around a flat wire conductor, the die comprising: a die body; and a die hole formed through the die body, the conductor to be inserted into the die hole in a conductor insertion direction, the die hole including: an entry portion having a cross section monotonically decreasing along the conductor insertion direction; and a coating portion including at least a sub-portion having a constant cross section, the cross section of the coating portion being a rectangle having four straight sides and four rounded corners, the coating portion having a flat inner surface corresponding to each straight side of the rectangular cross section of the coating portion, the coating portion having a rounded inner surface corner corresponding to each rounded corner of the rectangular cross section of the coating portion, each flat inner surface of the coating portion having an inwardly projecting protrusion, a top contour, perpendicular to the conductor insertion direction, of each protrusion being a circular arc, an elongated circular arc, an elliptical arc or a combination of these arcs, the maximum curvature of the top contour of each protrusion being larger than the maximum curvature of the rounded inner surface corners.