TWI637799B - Single-edged micro drill - Google Patents

Abstract

The invention provides a single-blade micro drill bit, which is provided with a spiral first groove, a second chip flute and a third from a first end face of the first end of the drill bit toward a second end. a chip flute, the first chip flute and the second chip flute are 180° rotationally symmetric about a core, and a part of the edge of the first chip flute forms a main cutting edge, and the second chip flute is on the foregoing The centrally symmetrical edge of the major cutting edge is cut away to form the aforementioned third chip flute, which does not form a cutting action.

Description

 Single-edged micro drill  

The present invention relates to the technical field of micro drills for printed circuit boards (PCBs), for example, to a single-edged micro drill.

A drill bit is required for drilling. A twist drill is a commonly used drill bit. The twist drill has two flutes arranged in a spiral shape on the outer peripheral surface, and a land portion is provided between the flutes, and the drill bit faces the flute. Two symmetrical cutting edges are provided at the intersecting ridge portions of the rake face in the rotational direction and the flank face on the rear side of the rake face. The two flutes of the twist drill are usually placed symmetrically with respect to the center of the center of rotation of the drill bit. They can be well balanced with a center-symmetrical cutting edge, and have good chip removal performance and high-precision hole machining. .

With the high integration and precision development of electronic products, printed circuit boards (PCBs) are gradually developing in the direction of small aperture, narrow line spacing, high density and multi-layer number, and the requirements for mechanical drilling, such as hole position accuracy and The rate of broken drills is getting higher and higher. The drill diameter of the drill bit for the PCB board (the diameter of the outer edge of the drill bit) is generally small to accommodate the need for a small aperture. However, in the case of a general twist drill, if a drill having a small drill diameter is formed, the wall thickness of the drill is reduced, the rigidity is lowered, and the drill is easily bent during the drilling process, resulting in a decrease in the accuracy of the drilling position. In addition, the PCB is generally in the compilation A glass fiber cloth formed of woven glass fiber is impregnated with a resin to form a prepreg resin blank, and a copper foil is laminated on the surface of the prepreg resin material to form a non-homogeneous composite material, and the bending of the glass fiber is sensitive to the positional accuracy of the hole. Therefore, when drilling a PCB with a small diameter drill, the hole position accuracy is lowered. Therefore, it is difficult to obtain good hole position accuracy by using a conventional twist drill bit with a small diameter of a small diameter drill bit, particularly a printed circuit board. CN200510105356.2 proposes a new structural drill with non-central symmetry of the double flutes relative to the center of rotation, the structure of the wall thickness (rigid) is ensured by forming the first flute, and the other flute is opposite to the first The flutes are non-centrally symmetrically offset, do not form the main cutting edge, can not be cut, and the groove length is smaller than the length of the first flute groove, which increases the certain wall thickness, thus increasing the rigidity of the drill bit and improving the rigidity. The accuracy of the drilling. However, the asymmetrically designed drill tip results in a centroid shift, which is prone to yaw during drilling and reduces drilling accuracy.

The embodiment of the invention provides a single-blade micro drill bit, which has better rigidity, reduces the centroid offset, reduces the deflection during the drilling, and improves the drilling precision.

The embodiment of the present invention adopts the following technical means: a single-blade micro drill bit, comprising: a first end portion and a second end portion; the first end portion is disposed opposite to the second end portion and located at two ends of the drill bit; a first end of the first end opens a first row in a direction toward the second end a chip flute, a second chip flute and a third chip flute, wherein the first chip flute, the second chip flute and the third chip flute are spiral, the first flute and the second chip The groove is 180° rotationally symmetric about the core, and a part of the edge of the first chip flute is a main cutting edge, and an edge of the second chip flute which is centrally symmetrical with the main cutting edge is cut off to form the third chip discharge. The groove, the aforementioned third chip flute does not have a cutting action.

Optionally, the third chip flute is in communication with the first chip flute and the second chip flute.

Optionally, the third chip flute is in parallel with the first chip flute and then spirally extends in a direction close to the second end.

Optionally, the third chip flute and the second chip flute are both blind grooves, and the length of the third chip flute and the second chip flute is smaller than the length of the first chip flute, and neither of The aforementioned first chip flutes are in communication.

Optionally, the top of the first end portion is provided with a chisel edge, and the portion of the chisel edge is cut away to form a fourth chip flute.

Optionally, the line connecting the first chip flute and the outer edge of the drill bit near the two end points of the drill tip is a first connection, and the third chip flute is intersected with the fourth chip flute. The end point of the line near the drill point is a first intersection point, and the end point of the third chip flute and the outer edge of the drill bit near the drill point is a second intersection point, and the connection between the first intersection point and the second intersection point is In the second connection, the angle between the first connecting line and the second connecting line is 45°-90°.

Optionally, the end point of the fourth chip flute and the second chip flute adjacent to the drill point is a third intersection, and the connection between the first intersection and the third intersection is a third connection. The angle between the third connecting line and the second connecting line is 5°-75°.

Optionally, the length of the second chip flute is 2.5 times to 4 times the diameter of the drill bit, and the length of the fourth chip flute is 1 to 4 times the diameter of the drill bit.

Optionally, the aforementioned first chip flute is a spiral groove having a helix angle in the range of 38°-42° and a constant spiral groove or helix angle in the range of 38°-42°.

Optionally, the aforementioned second chip flute is a helical groove having a helix angle in the range of 38°-42° and a constant spiral groove or helix angle in the range of 38°-42°.

Optionally, the aforementioned third chip flute is a spiral groove having a helix angle in the range of 38°-42° and a constant spiral groove or helix angle in the range of 38°-42°.

Optionally, the second chip flute groove depth is smaller than the groove depth of the first chip flute and greater than 10% of the bit radius.

The embodiment of the invention provides a single-blade micro drill bit, which is provided with a first spiral flute and a second flute from a first end surface of the first end of the drill bit toward a second end. And the third chip flute, the first chip flute and the second chip flute are 180° rotationally symmetric about the core, and a part of the edge of the first flute forms a main cutting edge, and the second chip flute The edge symmetrical with respect to the aforementioned main cutting edge is cut away to form the aforementioned third chip flute, and no cutting action is formed. By adjusting the first chip flute and the second flute, it is ensured that the main cutting edge has sufficient support to ensure the rigidity of the bit body, and the first chip flute and the second flute can be approached to the second end. The direction of chip removal improves the chip removal performance. At the same time, the first chip flute and the second chip flute are 180° rotationally symmetric, which reduces the centroid offset and reduces the drill pin compared with the asymmetric mode. The yaw of the time improves the drilling accuracy.

1‧‧‧First chip flute

11‧‧‧First connection

2‧‧‧Second chip flute

3‧‧‧ Third chip flute

31‧‧‧ first intersection

32‧‧‧Second intersection

33‧‧‧Second connection

4‧‧‧fourth chip flute

41‧‧‧ Third intersection

42‧‧‧ third connection

5‧‧‧Main cutting edge

6‧‧‧Corner

7‧‧‧Director

‧‧‧‧顶角

‧‧‧‧helix angle

θ‧‧‧An angle between the first chip flute and the third flute

γ‧‧‧An angle between the fourth chip flute and the third flute

L‧‧‧ Length of the guide along the axial direction of the drill

100‧‧‧ first end

200‧‧‧ second end

Fig. 1 is a partial structural schematic view showing the horizontal placement of a single-blade micro drill provided in Example 1 of the present invention.

Fig. 2 is a schematic structural view of a single-blade micro drill provided in Example 1 of the present invention.

Fig. 3 is a partially enlarged view of a portion A of Fig. 2 .

Fig. 4 is a partial structural schematic view showing a single-edged micro-drill according to a first embodiment of the present invention.

Fig. 5 is a partial schematic view showing the structure of a single-edged micro drill provided in the first embodiment of the present invention.

Fig. 6 is a partial structural view 3 of a single-blade micro drill provided in the first embodiment of the present invention.

Fig. 7 is a front elevational view showing a single-blade micro drill according to a first embodiment of the present invention.

Fig. 8 is a left side view of a single-blade micro drill according to a second embodiment of the present invention.

Fig. 9 is a schematic structural view of a single-blade micro drill according to a second embodiment of the present invention.

Fig. 10 is a partial enlarged view of a portion B of Fig. 9.

Fig. 11 is a partial structural schematic view showing a single-edged micro-drill according to a second embodiment of the present invention.

Fig. 12 is a partial schematic view showing the structure of a single-edged micro drill according to a second embodiment of the present invention.

The technical means of the present invention will be further described below in conjunction with the accompanying drawings and the embodiments of the present invention.

Example 1:

As shown in FIG. 1 to FIG. 7, the embodiment provides a single-blade micro drill including: a first end portion (100) and a second end portion (200); the first end portion 100 and the second end portion 200 oppositely disposed at both ends of the drill bit; from the first end surface of the first end portion 100 of the drill bit toward the second end portion 200, a first chip flute 1, a second flute 2, and a third portion are opened. The chip flute 3, the first flute (1), the second flute (2) and the third flute (3) are all spiral, and the first flute 1 and the second flute 2 The core is 180° rotationally symmetric about the center, and a part of the edge of the first chip flute 1 forms a main cutting edge 5, and an edge of the second chip flute 2 that is centrally symmetric with the main cutting edge 5 (ie, 180° rotationally symmetric) is The cutting is performed to form the third chip flute 3 without cutting action. The first end surface may refer to the side of the first end portion 100 that faces away from the second end portion 200. When there is only one cutting edge, that is, the main cutting edge 5, compared with the double cutting edge, only the rigidity of the main cutting edge 5 can be considered. By adjusting the first chip flute 1 and the second chip flute 2, the main cutting can be preferentially satisfied. The wall thickness behind the blade 5 is used to obtain a larger amount of support and to increase the rigidity of the main cutting edge 5. Both the first chip flute 1 and the second flute 2 can be chipped, which improves the chip discharging performance, and at the same time, the first chip flute and the second chip flute are 180° rotationally symmetric, compared with the asymmetric method. The center of mass is closer to the center of the drill bit, which reduces the offset of the center of mass, reduces the yaw during drilling, and improves the accuracy of drilling. The second chip flute 2 groove depth may be set to be smaller than the groove depth of the first chip flute 1 and greater than 10% of the bit radius. The groove depth refers to the depth at which the bottom of the groove is cut into the core. The groove depth of the spiral chip groove refers to the edge of the chip flute to the bottom of the chip flute along the radial direction of the bit. Since the second chip flute 2 is only for discharging the chips, in order to increase the rigidity of the main cutting edge 5 on the first flutes 1, the groove depth of the second flutes 2 can be reduced, and the main cutting edge can be increased. 5 rear support. However, in order to ensure chip capacity and chip removal performance, the groove depth of the second chip flute 2 should be greater than 10% of the radius of the bit.

In this embodiment, the third chip flute 3 and the second chip flute 2 are blind grooves, and the length of the third chip flute 3 and the second chip flute 2 is smaller than the length of the first chip flute 1 . And none of them communicate with the first chip flute 1. It is avoided that the metal substrate at the communication region with the first chip flute 1 is too small, the rigidity of the drill bit is lowered, the accuracy of the drilling is affected, and the problem of easy breakage is avoided. The first chip flute 1 may be a spiral groove having a helix angle β in the range of 35°-50° and a constant spiral groove or helix angle β in the range of 35°-50°. When the helix angle is too large, the pitch of the first chip flute 1 is relatively small, that is, the drill bit 1 of the same length has longer and more turns of the first chip flute 1 , and the amount of the metal substrate to be cut by the drill bit is relatively large. The rigidity of the drill bit deteriorates, the drilling accuracy decreases, and it is easy to break. When the helix angle is too small, the first chip flute 1 becomes less, and the chip performance and the chip discharging performance are both lowered. The helix angle can be selected from 38° to 42°, which can balance the good chip removal performance, chip handling performance and bit rigidity. At least one of the second chip flute 2 and the third flute 3 may also be a spiral groove having a helix angle of 35°-50° and a constant spiral groove or a helix angle of 35°-50°. The second chip flute 2 and the third flute 3 are prevented from communicating with the first flute 1 by adjusting the helix angle to ensure better rigidity of the bit.

The single-blade micro drill bit of the present embodiment further includes a fourth chip flute 4, and a chisel edge 6 is disposed at the top of the first end portion 100, and a portion of the chisel edge 6 is cut to form a fourth chip flute 4, and a fourth chip flute 4 may be located between the second chip flute 2 and the third flute 3, or may be only on the second flute 2 or the third flute 3, depending on the actual situation. By providing the fourth chip flute 4, the length of the chisel edge 6 is reduced, the cutting temperature is lowered, and the cross section in the second chip flute 2 and the third chip flute 3 region is reduced. After the blade 6, the chips entering the second chip flute 2 and the third flute 3 are reduced to avoid accumulation in the second flute 2 and the third flute 3, resulting in blockage of the chips in the blind trough.

The length of the second chip flute 2 can be 2.5 times to 4 times the diameter of the drill bit, and the length of the fourth chip flute 4 is 1 to 4 times the diameter of the drill bit, and in this range, better chip discharging performance can be obtained. While avoiding communication with the first chip flute. Wherein, the length of the second chip flute 2 and the length of the fourth flute 4 refer to the vertical distance between the two ends of the flute (the beginning and the end of the flute).

As shown in Fig. 7, when the apex angle α of the drill bit of the drill bit is too large, the cutting performance is lowered, the apex angle α is too small, the wear resistance of the drill tip is deteriorated, and the apex angle α can be 100°-140°, taking into account the drill bit. Wear resistance and cutting performance, generally 130 °, to obtain better wear resistance and cutting performance.

The single-blade micro drill bit of the present embodiment is a UC (undercut) type drill bit, that is, a guide portion 7 for guiding is protruded from the outer wall of the first end portion of the drill bit. Generally, the outer diameter of the guide portion 7 is The diameters of the holes to be drilled are equal to ensure the accuracy of the drilling, and the outer diameter of the drill bit behind the guide portion 7 is slightly smaller than the outer diameter of the guide portion 7, reducing the friction between the outer wall of the rear drill bit and the inner wall of the hole. The length L of the guiding portion in the axial direction of the drill bit can be set to 0.4 mm-0.6 mm to achieve the guiding performance, obtain better drilling precision, and avoid the heat generation caused by the excessive friction area caused by the too long guiding portion 7. Too large, the binder cobalt in the drill body made of a cemented carbide material is easily oxidized, resulting in a decrease in wear resistance of the drill bit and even a problem that the drill bit is easily broken. The drill diameter of such a single-blade micro drill can be 0.15mm-0.7mm, and this structure can be used to obtain better drilling precision. In the present embodiment and the following embodiments, the aforementioned rear side refers to a direction toward the second end portion 200.

Example 2:

Different from Embodiment 1, as shown in FIG. 8 to FIG. 12, the third chip flute 3 of the present embodiment communicates with the first chip flute 1 and the second chip flute 2, and the third chip flute 3 and the third A flute 1 is connected and then spirally extends in a direction close to the second end 200. After the third chip flute 3 communicates the first chip flute 1 and the second flute 2, the 1 chip is discharged from the first chip flute 1 and the second flute 2 and the third flute 3 are The discharged chips will collide with each other at the intersection to prevent the chips from continuing to entangle in the rear chip flutes and affect the chip removal. The third chip flute 3 communicates with the first chip flute 1 and spirally extends in a direction close to the second end portion 200, which can increase the chip performance and the chip discharging performance of the first chip flute. The groove length of the third chip flute 3 may be equal to the groove length of the first chip flute 1, that is, the end of the first flute 1 extending to the cutting length direction of the drill bit, thereby improving the chip removal performance in the entire cutting length direction. .

As shown in FIG. 8, the line connecting the first chip flute 1 and the outer edge of the drill bit of the present embodiment near the two end points of the drill point is the first line 11, the third chip flute 3 and the The end point of the intersection of the four chip flutes 4 near the drill point is the first intersection point 31, and the end point of the third chip flute 3 and the outer edge of the drill bit near the end of the drill point is the second intersection point 32, the first intersection point 31 The line connecting the second intersection 32 is the second line 33, and the angle between the first line 11 and the second line 33 is the angle θ between the first chip flute 1 and the third chip flute 3. When θ is too large, the outer edge of the first chip flute 1 is cut off, and a better support structure cannot be formed, which reduces the rigidity of the drill bit. When the θ is too small, the third chip flute 3 cannot be cut to the second flute. 2 cutting edge. θ can be 45°-90°, which is suitable.

The end point of the fourth chip flute 4 and the second chip flute 2 near the drill point is the third intersection point 41, and the line connecting the first intersection point 31 and the third intersection point 41 is the third connection line 42, the third connection The angle between the line 42 and the second line 33 is the angle γ between the third chip flute 3 and the fourth chip flute 4. The value of γ mainly affects the length of the chisel edge 6, which is too large or too small to cause the chisel edge 6. The length is too small or too large, resulting in a high cutting temperature or a good positioning accuracy in the initial drilling. Optionally, γ is between 5° and 75° Within the scope. Alternatively, in Embodiment 1, the values of θ and γ are also within the scope of the present embodiment.

[Industry Utilization]

The single-blade micro drill bit provided by the embodiment of the invention can ensure that the main cutting edge has sufficient support amount to ensure the rigidity of the bit body, the first chip flute and the second by adjusting the first chip flute and the second chip flute. The chip flutes can be chipped toward the second end, which improves the chip removal performance. At the same time, the first chip flute and the second chip flute are 180° rotationally symmetric, which is reduced compared with the asymmetric mode. The offset of the center of mass reduces the yaw during drilling and improves the drilling accuracy.

Claims (12)

A single-edged micro drill bit is characterized in that it comprises: a first end portion (100) and a second end portion (200); the first end portion (100) is disposed opposite to the second end portion (200) and is located at the drill bit Both ends of the first end portion (100) of the drill bit are provided with a first chip flute (1), a second chip flute (2) and a direction toward the second end portion (200). The third chip flute (3), the first chip flute (1), the second chip flute (2) and the third flute (3) are spiral, the first flute (1) And the second chip flute (2) is 180° rotationally symmetric about the core, and a part of the edge of the first chip flute (1) is a main cutting edge (5), and the second chip flute (2) The edge symmetrical with respect to the aforementioned main cutting edge (5) is cut away to form the aforementioned third chip flute (3), and the third chip flute (3) has no cutting action. The single-blade micro drill according to the first aspect of the invention, wherein the third chip flute (3) communicates with the first chip flute (1) and the second chip flute (2). The single-blade micro drill according to the second aspect of the invention, wherein the third chip flute (3) communicates with the first chip flute (1) and is arranged adjacent to the second end (200). The spiral extends. The single-blade micro drill according to the first aspect of the invention, wherein the third chip flute (3) and the second chip flute (2) are blind grooves, and the third chip flute (3) And the length of the second chip flute (2) is smaller than the length of the first chip flute (1), and is not in communication with the first flute (1). The single-edged micro-drill according to any one of claims 1 to 4, wherein the top end of the first end portion (100) is provided with a chisel edge (6), and a portion of the chisel edge (6) is The cutting is performed to form a fourth chip flute (4). The single-edged micro-drill according to the fifth aspect of the invention, wherein the line connecting the first chip flute (1) and the outer edge of the drill bit near the two end points of the drill tip is the first connection. (11), the end point of the third chip flute (3) and the fourth chip flute (4) adjacent to the drill point is a first intersection point (31), and the third chip flute (3) The end point of the outer edge of the drill bit near the drill point is a second intersection point (32), and the line connecting the first intersection point (31) and the second intersection point (32) is a second connection line (33), the foregoing The angle between the connecting line (11) and the aforementioned second connecting line (33) is 45°-90°. The single-edged micro-drill according to the sixth aspect of the invention, wherein the end point of the fourth chip flute (4) and the second chip flute (2) adjacent to the drill point is a third intersection point ( 41) The connection between the first intersection point (31) and the third intersection point (41) is a third connection line (42), and the angle between the third connection line (42) and the second connection line (33) is 5°-75°. The single-blade micro drill according to the fifth aspect of the invention, wherein the length of the second chip flute (2) is 2.5 to 4 times the diameter of the drill, and the length of the fourth chip flute (4) is The diameter of the drill is 1 to 4 times the diameter. The single-blade micro drill according to any one of claims 1 to 4, wherein the first chip flute (1) is a spiral groove or spiral having a helix angle in the range of 38°-42°. A spiral groove with an angle in the range of 38°-42°. The single-blade micro drill according to any one of claims 1 to 4, wherein the second chip flute (2) is a spiral groove or spiral having a helix angle in the range of 38°-42°. A spiral groove with an angle in the range of 38°-42°. The single-blade micro drill according to any one of claims 1 to 4, wherein the third chip flute (3) is a spiral groove or spiral having a helix angle in the range of 38°-42°. A spiral groove with an angle in the range of 38°-42°. The single-blade micro drill according to any one of claims 1 to 4, wherein the second chip flute (2) has a groove depth smaller than a groove depth of the first chip flute (1) and is larger than 10% of the drill radius.