Rotary cutting tool having tool holder with conical internal thread and replaceable cutting head with straight external thread, and said tool holder

A tool holder (24), having a holder longitudinal axis (C) extending in the forward (DF) to rearward direction (DR), comprising a female coupling member (68) having an internal thread (72) extending rearwardly from a holder forward surface (70), the holder forward surface (70) extending transversely with respect to the holder longitudinal axis (C), wherein:

• the internal thread (72) of the female coupling member (68) is a conical thread;
• the internal thread (72) comprises an internal thread ridge (74) extending helically about an internal thread axis (D) and also about a cylinder (Y), the internal thread ridge (74) comprising forward and rearward internal flank surfaces (76, 78) and an internal top surface (80) extending therebetween;
• the forward and rearward internal flank surfaces (76, 78) face in opposite axial directions (DF, DR) and delimit a helical internal thread groove (82) that comprises an internal bottom surface (84);
• at least one of the internal thread ridge (74) and the internal thread groove (82) extend about a respective cone (K) having a cone angle (γ);
• and
• the cone angle (γ) is in the range of 0.02°≤γ≤1.6°.

A rotary cutting tool (20) having a longitudinal axis (L) and extending in a forward (DF) to rearward direction (DR), comprising:

• a tool holder (24), having a holder longitudinal axis (C) extending in the forward (DF) to rearward direction (DR), comprising a female coupling member (68) having an internal thread (72) extending rearwardly from a holder forward surface (70), the holder forward surface (70) extending transversely with respect to the holder longitudinal axis (C), wherein:
• the internal thread (72) of the female coupling member (68) is a conical thread;
• the internal thread (72) comprises an internal thread ridge (74) extending helically about an internal thread axis (D) and comprising forward and rearward internal flank surfaces (76, 78);
• and an internal top surface (80) extending therebetween;
• the forward and rearward internal flank surfaces (76, 78) face in opposite axial directions (DF DR) and delimit a helical internal thread groove (82) that comprises an internal bottom surface (84);
• at least one of the internal thread ridge (74) and the internal thread groove (82) extend about a respective cone (K) having a cone angle (γ);
• and
• the cone angle (γ) is in the range of 0.02° ≤γ≤1.6°;
• and
• a replaceable cutting head (22) having a head longitudinal axis (A) and comprising:
• a forward portion forming a cutting portion (26);
• and
• a rearward portion forming a mounting portion (28), the mounting portion (28) comprising a male coupling member (38) having an external thread (42) and protruding rearwardly from a head base surface (40), the head base surface (40) extending transversely with respect to the head longitudinal axis (A), and defining a boundary between the cutting portion (26) and the mounting portion (28);
• wherein:
• the external thread (42) of the male coupling member is a straight thread, whose thread ridge extends about a cylinder;
• and
• the rotary cutting tool (20) is adjustable between:
• a released position in which the male coupling member (38) is located outside of the female coupling member (68), and the internal and external threads are not threadingly engaged to one another, and
• a locked position in which the male coupling member (38) is removably retained in the female coupling member (68) with the internal and external threads threadingly engaged to one another.