TWI532551B - Back-tapered drill structure - Google Patents

Description

Inverted cone bit structure

The present invention relates to a drill bit structure, and more particularly to an inverted cone type drill bit structure in which the radius of the spiral side edge of the drill blade portion is tapered from the front end of the drill blade portion toward the shank portion.

Nowadays, in order to meet the market demand for diversified, multi-layered and high-density of printed circuit board substrate materials, the micro-diameter perforations on newly developed circuit boards are usually 0.05 mm to 2 mm in diameter, and such micro-diameter perforations are required to be high. Precision drill bits are drilled. When the drill bit is drilling, the drill bit needs to be drilled down to a certain depth before lifting the drill bit.

Figure 1 is a side view of a conventional drill bit. The surface of the drill blade 2 of the drill bit 1 has a spiral side edge 4 of equal diameter. When the drill bit 1 is being drilled, the entire spiral side edge 4 will be In contact with the wall of the hole, during the process of drilling and lifting, the cutting edge portion 2 tends to excessively pull the wall of the hole, resulting in a hole edge bump (Burr), which is disadvantageous for the subsequent processing of the printed circuit board.

In order to solve the above problems, one of the objects of the present invention is to provide an inverted cone type drill bit structure in which the radius of the spiral side edge of the drill blade portion is tapered from the front end of the drill blade portion toward the shank portion to improve the drilling operation. The problem of the edge of the hole caused by the drill bit being drilled and lifted up has a better chip removal capability.

In order to achieve the above object, an inverted cone type bit structure according to an embodiment of the present invention includes a shank portion, and a drill blade portion is disposed at one end of the shank portion, and the outer surface of the drill blade portion is provided with two spiral grooves to form a double spiral The side edge, the front end of the drill blade portion forms a blade surface structure, and the blade surface structure comprises two main blade faces and two blade faces symmetrically disposed on one of the cutting edge portions, and the two main blade faces and the two minor blade faces are formed by the blade tip The static point is inclined toward the shank, and the radius of the spiral side edge tapers from the front end of the drilling edge toward the shank until the shank portion, wherein the radius of the spiral side edge is the farthest edge of the spiral side edge to the shank The shortest distance of the axis of rotation, and the spiral side edge The slope of the line at the farthest edge is between 0.05% and 0.3%.

The purpose, technical contents, features, and effects achieved by the present invention will become more apparent from the detailed description of the appended claims.

2 is a schematic structural view of an inverted cone type bit according to a first embodiment of the present invention. As shown, the inverted cone type bit structure 8 includes a shank portion 9 and a drill edge portion 10, and the cutting edge portion 10 is disposed on At one end of the shank portion 9, the outer surface of the drill blade portion 10 is provided with two spiral grooves 11 to form a two-spiral side edge 12 having a radius which tapers from the front end of the drill blade portion 10 toward the shank portion 9.

Referring to FIG. 2, the variation of the radius reduction is illustrated by the line L of the farthest edge of each spiral side edge 12, wherein the shortest distance defining the farthest edge of the spiral side edge 12 from the rotation axis O is the spiral side edge 12. The radii are exemplified by the adjacent one of the first spiral side edge 12a and the second spiral 12b side edge, and the shortest distance from the farthest edge of the first and second spiral side edges 12a, 12b to the rotation axis O represents the first The radius of the second spiral side edges 12a, 12b is represented by R1 and R2, respectively, and the radius difference between the two is ΔR = R1 - R2, and the pitch of the first and second spiral side edges 12a, 12b is represented by Δs. Then the slope of the line L is m = ΔR / Δs, and the slope m is between 0.05% and 0.3%. It should be noted that the slopes of the radius R1, R2 or the line L of the first spiral side edge 12a and the second spiral side edge 12b of FIG. 2 are for illustrative purposes only and do not represent the actual ratio of the bit structure.

In the above first embodiment, the two spiral grooves 11 each have a fixed and identical spiral inclination angle θ, and the angle of the spiral inclination angle θ is between 20 degrees and 60 degrees, but the spiral inclination angle θ is not limited to a fixed angle. The two spiral grooves 11 may also each have a variable helix angle θ, and the angle of the helix angle θ may vary between 10 degrees and 80 degrees.

3 is an inverted cone type bit structure according to a second embodiment of the present invention, the inverted cone type bit structure 8 includes a shank portion 9 and a drill edge portion 10, and the drill edge portion 10 is disposed on the shank portion One end of the 9th, wherein the cutting edge portion 10 includes a tip end portion 10a, a middle portion 10b and a body In the section 10c, the outer surface of the cutting edge portion 10 is provided with two spiral grooves 11 to form two spiral side edges 12, and the two spiral grooves 11 are symmetrically separated at the tip end portion 10a, and the spiral inclination angles θ of the two spiral grooves 11 are not equal. Or one of the spiral grooves is a variable helical inclination angle θ such that the two spiral grooves 11 are gradually approached in the intermediate portion 10b until the body segments 10c are merged together, in this embodiment, the spiral The radius of the side edge 12 tapers from the front end of the cutting edge portion 10 toward the shank portion 9, and the slope of the line L of the farthest edge of the spiral side edge 12 is between 0.05% and 0.3%.

In the first embodiment and the second embodiment, the front end of the cutting edge portion 10 shown in FIG. 2 and FIG. 3 forms a blade surface structure 30. As shown in FIG. 4, the blade surface structure 30 includes: two main blade faces 32 and The two sub-blades 33 are symmetrically disposed on one of the cutting edge portions 31 of the cutting edge portion 10 for cutting the surface of the workpiece by the blade structure 30, and on the other hand, the outer surface of the cutting edge portion 10 can be wrapped. Covering a film layer (not shown), the material of which is a metal compound, a carbon compound or a mixture of the above components, and preferably titanium nitride (TiN), titanium aluminum nitride (TiAlN), Diamond coating or Diamond like Coating. Further, the drill blade portion 10 and the shank portion 9 may be integrally formed of a tungsten carbide rod, or may be a tungsten carbide material shank portion 9 and a tungsten carbide material drilled by welding or an adhesive. The blade portions 10 are joined together, or the shank portion 9 made of stainless steel and the blade portion 10 made of tungsten carbide are joined together by means of welding or an adhesive.

In the above, in addition to the joining manner of welding or adhesive, the cutting edge portion 10 can be inserted into the shank portion 9 in an inserting manner. In one embodiment, an inner hole is provided in one end surface of the shank portion 9 (in the figure) Not shown), and one end of the cutting edge portion 10 has an insertion end (not shown), the inner diameter of the inner hole is less than or equal to the outer diameter of the insertion end, and the difference is between 0 micrometers (μm) and 30 Between the micrometers, the insertion end of the drill blade portion 10 is press-fitted into the inner hole of the shank portion 9, so that the drill blade portion 10 and the shank portion 9 are combined.

In summary, the present invention has a structure in which the radius of the spiral side edge of the drill blade portion is tapered from the front end of the drill blade portion toward the shank portion, and the gap between the two spiral side edges and the upper hole wall is larger when the drill bit is pressed down. It can improve the chip removal ability during drilling, especially when lifting the drill bit, only the front end of the drill bit is rubbed against the hole wall, which can effectively reduce the excessive friction between the middle section of the drill bit and the hole wall, resulting in the edge of the hole. Prominent problems.

The embodiments described above are only intended to illustrate the technical idea and the features of the present invention, and the purpose of the present invention is to enable those skilled in the art to understand the contents of the present invention and to implement the present invention. That is, the equivalent variations or modifications made by the spirit of the present invention should still be included in the scope of the present invention.

1‧‧‧ drill bit

2‧‧‧Drilling

4‧‧‧Spiral side blade

8‧‧‧Inverted cone bit structure

9‧‧‧Drilling handle

10‧‧‧Drilling

10a‧‧‧ tip segment

10b‧‧‧ middle section

10c‧‧‧ body section

11‧‧‧Spiral groove

12, 12a, 12b‧‧‧ spiral side edge

O‧‧‧Rotation axis

Radius of R1, R2‧‧

△R‧‧‧radius difference

L‧‧‧ connection

△s‧‧‧ spacing

Θ‧‧‧spiral dip

30‧‧‧Mask structure

31‧‧‧The tip of the knife is still

32‧‧‧Major face

33‧‧‧Sub-blade

Figure 1 is a schematic view showing a conventional drill bit structure.

Fig. 2 is a schematic view showing the structure of a reverse tapered drill bit according to a first embodiment of the present invention.

Fig. 3 is a schematic view showing the structure of a reverse tapered drill bit according to a second embodiment of the present invention, in which spiral grooves are gradually approached and merged.

Fig. 4 is a schematic view showing a blade surface structure according to an embodiment of the present invention.

8‧‧‧Inverted cone bit structure

9‧‧‧Drilling handle

10‧‧‧Drilling

11‧‧‧Spiral groove

12, 12a, 12b‧‧‧ spiral side edge

O‧‧‧Rotation axis

Radius of R1, R2‧‧

△R‧‧‧radius difference

L‧‧‧ connection

△s‧‧‧ spacing

Θ‧‧‧spiral dip

Claims (8)

An inverted cone type drill bit structure comprising: a drill shank portion and a drill edge portion disposed at one end of the drill shank portion, the outer surface of the drill blade portion is provided with two spiral grooves to form a two-spiral side edge, the drill The front end of the blade portion has a blade surface structure, and the blade surface structure includes two main blade faces and two blade faces symmetrically disposed on one of the blade edge points of the drill blade portion, and the two main blade faces and the two minor blade faces are formed by the blade a sharp point is inclined toward the shank portion, and a radius of the spiral side edge tapers from a front end of the drilling edge portion toward the shank portion to the shank portion, wherein a radius of the spiral side edge is the spiral side The shortest distance from the farthest edge of the blade to the axis of rotation of the shank portion, and the slope of the line connecting the farthest edge of the spiral side edge is between 0.05% and 0.3%. The inverted cone type bit structure of claim 1, wherein the two spiral grooves each have a fixed and identical spiral inclination angle of between 20 and 60 degrees. The inverted cone type bit structure of claim 1, wherein at least one of the two spiral grooves has a variable helix angle, the angle of the helix angle being between 10 degrees and 80 degrees. The inverted taper bit structure of claim 3, wherein the cutting edge portion comprises a tip end section, an intermediate section and a body section, wherein the spiral groove is symmetrically separated from the tip end section, and the spiral groove is The troughs gradually approach the middle section and merge together in the body section. The inverted taper bit structure of claim 1, wherein the shank portion and the drill edge portion are integrally formed of a tungsten carbide bar. The inverted taper bit structure according to claim 1, wherein the material of the shank portion is stainless steel, the material of the drill portion is tungsten carbide, and the shank portion and the drill portion are welded or adhered. The agents are joined together. The inverted taper bit structure of claim 1, wherein an end surface of one end of the drill shank portion is provided with an insertion end, and an inner diameter of the inner diameter hole is less than or equal to the insertion end The outer diameter of the insertion hole is inserted into the inner hole, wherein a difference between an inner diameter of the inner hole and an outer diameter of the insertion end is between 0 micrometers (μm) and 30 micrometers. The inverted cone type drill bit structure according to claim 1, wherein the outer surface of the drill blade portion is coated with a film The layer is made of a metal compound, a carbon compound or a mixture of the above components.