Please select the most similar patent number from A, B, C and D. Which number is?
Disclosed is a rotary cutting tool, comprising a cutting portion (10), wherein the cutting portion (10) is provided with an auxiliary spiral groove (102) and a plurality of right-handed main spiral grooves (101) with the same spiral angle. The auxiliary spiral groove (102) comprises a left-handed spiral groove spiralling up from a front end of the cutting portion (10) to a rear end thereof. The auxiliary spiral groove which spirals up and the main spiral grooves are provided with a plurality of cutting teeth (130) with trapezoidal sections at the cutting portion (10). Along the spiral direction of the auxiliary spiral groove, the tooth widths of adjacent cutting teeth (130) are partially superposed. Since the tooth shape of the rotary cutting tool is of an approximately rectangular trapezoidal structure, it is ensured that the tooth width is substantially unchanged in the process of cutting and as abrasion increases, thereby ensuring the stability of cutting. Moreover, the alternation of teeth on the rotary cutting tool helps to remarkably improve chip-removal performance and cutting performance, so that not only are machined board edges of good quality, but also the service life of the cutting tool is prolonged.
A: A miniature drill bit. The miniature drill bit comprises: a first rake face, a first flank face, a second rake face and a second flank face that are arranged at the position of a drill point; a first spiral groove extending from the drill point to a drill tail, and a second spiral groove symmetrical to the first spiral groove, the first spiral groove being intersected with the first rake face to form a first cutting edge, and the second spiral groove being intersected with the second rake face to form a second cutting edge; and a bias groove arranged at the position of a large-bit area of the drill bit, the bias groove being intersected with the second rake face, so that the length of the second cutting edge is smaller than that of the first cutting edge, and the bias groove being intersected with the second spiral groove.
B: A drill bit for drilling a PCB comprises a body (10). One end of the body (10) is a drill tip, and a groove and breadth ratio constant segment and a groove and breadth ratio alternating change segment are sequentially disposed from the end where the drill tip is located to the other end of the body (10). A long spiral groove (101) and a short spiral groove (102) that are spirally surrounding and that are not intersected are formed in the outer side of the body. The groove and breadth ratio of each of the long spiral groove (101) and the short spiral groove (102) is constant at the groove and breadth ratio constant segment. The groove and breadth ratio of each of the long spiral groove (101) and the short spiral groove (102) changes alternately at the groove and breadth ratio alternating change segment. The short spiral groove of the groove and breadth ratio constant segment is connected to a staggered groove staggered with the short spiral groove. In the drill bit for drilling a PCB, the double-spiral-groove non-intersection design is used, the groove and breadth ratio alternately changes on the rear section of the drill bit, the two grooves discharge cuttings independently, the drill bit is unlikely to be blocked by the cuttings, and the cutting temperature can be controlled in a small range. In addition, the area of a cross section entity of the spiral groove and the core thickness taper can be increased, the bend resistance strength of the drill bit is improved, the hole site machining precision is high, and the machining quality of a drilled hole is good.
C: A transversely-cutting compound drill bit, comprising a body (10). The body (10) comprises thereon multiple chip accommodating grooves (5) rotatedly provided according to a first right-handed helical line (11), and multiple cutting units (20) distributed on second right-handed helical lines (12) on either side of the chip accommodating grooves (5). The cutting units (20) comprise cutting teeth (4) and chip separating grooves (6) corresponding to the cutting teeth (4). The cutting teeth (4) are successively distributed in groups on the second right-handed helical lines (12) next to the corresponding chip separating grooves (6). The multiple chip separating grooves (6) are in communication with the chip accommodating grooves (5) The cutting teeth and the chip accommodating grooves of the transversely-cutting compound drill bit are helically distributed along the axis, thus increasing cutting and chip removal effects.
D: A cutting tool and a cutter head structure (100) thereof. The cutter head structure (100) comprises a cutting edge portion (2), and the cutting edge portion (2) comprises a cutting body (21). The outer surface of the cutting body (21) is a cambered surface protruding forward, and is provided with a first cutting edge (22) and at least two second cutting edges (23). The first cutting edge (22) extends from one side of the cutting body (21) to the top region and then to the other side of the cutting body (21), the second cutting edges (23) are respectively disposed at two ends of the first cutting edge (22). A first chip groove (24) is defined between the first cutting edge (22) and the adjacent second cutting edge (23), and the width of the first chip groove (24) gradually increases from the top region to the two ends of the cutting body (21). The cutting tool provides high processing accuracy and stability and good chip discharging properties, and the service life of the cutting tool can be greatly prolonged.
Answer: D