PURPOSE: To enable automatic and uniform heating of spherical cakes by forming grooves having circular cross-section on the inner face on the surface of a heating cylinder in nearly circumferential direction, supporting the heating cylinder in nearly horizontal state, charging spherical cakes into the cylinder and heating the cakes while rotating the heating cylinder on a horizontal shaft.
CONSTITUTION: A cylindrical heating cylinder 5 is made of a metal plate. Ball roller grooves 5a, 5b, 5c, etc., having circular cross-section with a radius nearly equal to the radius of the spherical cake 1 to be heated are formed on the inner surface of the cylinder 5 in nearly circumferential direction. Spherical cakes 1 are charged into the heating cylinder 5 and the cylinder is supported in nearly horizontal state and rotated on a horizontal shaft in the direction of the arrow L to cause the rotation of the spherical cake in the direction of the arrow l. The heating cylinder 5 is heated from under with a burner, etc., to uniformly heat a number of spherical cakes 1 while automatically rotating the cakes.