CN219310161U - Special-shaped hole drill bit - Google Patents

Abstract

The application discloses dysmorphism hole drill bit, wherein this dysmorphism hole drill bit includes: the drill bit comprises a handle and a cutting part, wherein a drill point is formed at one end of the cutting part, the other end of the cutting part is intersected with the handle, chip grooves are formed in the periphery of the cutting part and extend from the drill point to the handle in a spiral mode, the four chip grooves are arranged in a circumferential array mode of the cutting part, edges of the chip grooves intersect in the periphery of the cutting part to form a circumferential cutting edge, and the core thickness of the cutting part is greater than or equal to 80% of the diameter of the cutting part. Adopt the dysmorphism hole drill bit that this application disclosed, can improve the stability of earhole self when processing, improve the drill bit shake problem, reduce the risk of the broken sword of drill bit, stability improves and also makes processingquality improve, has reduced the burr when earhole processing.

Description

Special-shaped hole drill bit

Technical Field

The application relates to the technical field of PCBs (Printed Circuit Board, printed circuit boards), in particular to a special-shaped hole drill bit.

Background

At present, thick copper plates are widely used in PCB manufacture. The application fields of the thick copper plate PCB are as follows: mobile phones, microwaves, aerospace, satellite communication, network base stations, hybrid integrated circuits, power supply high-power circuits and the like. The application of the thick copper plate can lead the core component PCB of the electronic equipment product to have longer service life, and simultaneously, the application of the thick copper plate is greatly helpful for the volume simplification of the electronic equipment.

To increase the routing density, some PCBs design the vias as earholes, which are made up of one large hole and two small holes located on either side of and partially overlapping the large hole. Compared with a conventional round via hole, the through-flow capacity can be improved through the design of the lug hole, compared with a groove-shaped via hole, the drilling cost of the design of the lug hole is lower, and the wiring of the PCB is not affected.

Although the design of the earhole has the advantages, the earhole belongs to a special-shaped hole and has the problem of difficult processing. On one hand, due to uneven stress, the drill bit is easy to shake or even break during drilling, so that the via hole is damaged or even scrapped; on the other hand, the overlapping position of the big hole and the small hole is easy to form burrs during processing, the burrs are easy to generate due to the instability of the drill bit, additional repair is needed to be carried out on the through hole in the follow-up process, and the repair difficulty of the burrs of the miniature through hole is high. There is an urgent need for a solution to improve the problem of bit jitter and hole burrs.

Disclosure of Invention

Embodiments of the present application aim to address at least one of the problems of the prior art. Therefore, the embodiment of the application provides a special-shaped hole drill bit, which can reduce burrs during the processing of the earholes, reduce the risk of cutter breakage and improve the yield of the processing of the earholes.

Embodiments of one aspect of the present application provide a shaped hole drill bit. The special-shaped hole drill bit comprises a handle and a cutting part, wherein a drill point is formed at one end of the cutting part, the other end of the cutting part is intersected with the handle, chip grooves are formed in the periphery of the cutting part, the chip grooves spirally extend from the drill point to the handle, the four chip grooves are arranged in a circumferential array along the cutting part, edges of the chip grooves intersect at the periphery of the cutting part to form a circumferential cutting edge, and the core thickness of the cutting part is greater than or equal to 80% of the diameter of the cutting part.

Further, the core thickness is 80% to 90% of the diameter of the cutting portion.

Further, the wall surfaces of the junk slots are in smooth transition.

Further, the junk slots comprise a first arc section and a second arc section, the intersection line of the first arc section and the end face of the drill tip forms an end face cutting edge, and the second arc section is intersected with the first arc section of the adjacent junk slot.

Further, the curvature radius of the first arc section is smaller than that of the second arc section, the curvature center of the first arc section is located at the inner side of the cutting portion, and the curvature center of the second arc section is located at the outer side of the cutting portion.

Further, the helix angle of the flutes is 26 ° to 30 °.

Further, the end face cutting edge comprises end face main cutting edges arranged in a circumferential array or the end face cutting edge comprises end face main cutting edges and end face auxiliary cutting edges alternately arranged in a circumferential direction.

Further, the drill tip comprises a chisel edge, the chisel edge is arranged corresponding to the main cutting edge of the end face, and the chisel edge is intersected with the axis of the drill tip.

Further, the apex angle of the cutting portion is 106 ° to 110 °.

Further, the diameter of the cutting portion is less than or equal to 0.5mm.

The technical scheme of the special-shaped hole drill bit in the embodiment of the application has the following beneficial effects: firstly, compared with the prior drill bit, the special-shaped hole drill bit increases the core thickness of the cutting part, so that the rigidity of the cutting part is enhanced, the stability of the cutting part is improved when the cutting part is stressed unevenly, and the cutter breaking accident is not easy to happen; secondly, four circumferential cutting edges are formed on the periphery of the cutting part and are simultaneously contacted with the hole wall, so that the stability of the special-shaped hole drill is enhanced, the hole wall can be scraped by the circumferential cutting edges, burrs are cleaned, and the surface quality of the hole wall is improved; finally, through making adjacent junk slot direct intersection, reduced the contact surface of cutting portion's periphery and pore wall to reduced the cutting moment of torsion, also can play the effect of reinforcing stability equally, consequently, the dysmorphism hole drill bit can improve the stability of earhole self when processing, improves the drill bit shake problem, and stability improves also makes processingquality improve, has reduced the burr when earhole processing.

Additional aspects and advantages of the application will be set forth in part in the description which follows. As such, portions will be apparent from the description which follows, or may be learned by practice of the application.

Drawings

FIG. 1 is a schematic diagram of some via designs currently employed in PCBs;

FIG. 2 is a schematic structural view of a shaped hole drill bit according to some embodiments of the present application;

FIG. 3 is a schematic cross-sectional view of a cutting portion of a shaped hole drill bit in some embodiments of the present application;

FIG. 4 is an enlarged view of a portion of area A of FIG. 2;

FIG. 5 is a schematic view of the structure of the drill tip of a shaped hole drill bit in some embodiments of the present application;

fig. 6 is a schematic view of the structure of the drill tip of the shaped hole drill in other embodiments of the present application.

In the figure:

100-handle, 200-cutting part, 210-junk slot, 211-first arc section, 212-second arc section, 213-straight line section, 220-circumferential cutting edge, 230-main end face cutting edge, 240-auxiliary end face cutting edge, 250-chisel edge.

Detailed Description

Embodiments of the present application are described in detail below, examples of which are illustrated in the accompanying drawings, wherein like or similar reference numerals refer to like or similar elements or elements having like or similar functions throughout. The embodiments described below by referring to the drawings are exemplary only for the purpose of explaining the present application and are not to be construed as limiting the present application. The technical solutions between the embodiments of the present application may be combined with each other based on the implementation of those skilled in the art.

In this application, terms like "first" or "second" are used for descriptive purposes only and are not to be construed as indicating or implying a relative importance or the number of technical features indicated.

Currently, the through holes of the PCB are of the types of round holes, slots, earholes, etc., and referring to fig. 1, fig. 1 (a), (b), and (c) are examples of round holes, slots, and earholes, respectively. The slots and earholes have a larger circumference than the circular holes, and thus the through-flow capability is stronger, and the adverse effect of the earholes on the PCB wiring is smaller than the slots, and thus the use of the earholes is becoming increasingly common. However, the processing yield of the earhole still needs to be improved.

Factors affecting the earhole processing yield include both burrs and jitter.

The burrs are divided into orifice burrs and connecting hole burrs, on one hand, copper materials have good toughness and ductility, and cut materials are easy to adhere and remain to form burrs; on the other hand, the ear hole needs to be drilled for many times during processing, and the hole connecting part (the overlapped part of the big hole and the small hole) lacks support during secondary drilling, so that the drill bit is easy to shake and unstably, the cutting precision is reduced, the cutting is incomplete, and burrs are formed. The superposition of the above causes that burrs are extremely easily formed in the ear hole processing of the thick copper plate PCB.

Subsequent cleaning of burrs is relatively complex, and particularly for earholes with smaller apertures (such as micro earholes with larger apertures with diameters below 0.5 mm), the cleaning difficulty is higher, resulting in reduced production efficiency of the PCB. Incomplete burr cleaning can easily cause short circuit or other problems when the PCB product is used, and seriously affects the quality of the PCB product.

Because the size of the earhole of the PCB is smaller, the cutting part 200 of the drill is required to have a larger length-diameter ratio, and because the overlapping part lacks support, during the second drilling, the cutting part 200 of the drill is stressed unevenly, and the problem of shaking or breaking during feeding is easy to occur, so that the processing precision of the earhole is greatly reduced, and the breaking may even cause the scrapping of the current earhole. If the cutter is broken, a certain time is required for taking out the drill bit and replacing the new drill bit, and the production efficiency of the PCB is reduced.

Embodiments of one aspect of the present application provide a shaped hole drill bit. Referring to fig. 2 and 3, the special-shaped hole drill includes: the shank portion 100 and the cutting portion 200, one end of the cutting portion 200 forms a drill tip, the other end of the cutting portion 200 intersects the shank portion 100, a chip groove 210 is formed in the outer periphery of the cutting portion 200, the chip groove 210 extends from the drill tip to the shank portion 100 in a spiral manner, four chip grooves 210 are arranged in a circumferential array of the cutting portion 200, edges of the chip grooves 210 intersect at the outer periphery of the cutting portion 200 to form a circumferential cutting edge 220, and the core thickness of the cutting portion 200 is greater than or equal to 80% of the diameter of the cutting portion 200.

First, referring to fig. 3, in the present application, the "core thickness" refers to the core thickness, that is, the minimum diameter dimension of the cutting portion 200, and the "diameter of the cutting portion 200" refers to the maximum diameter dimension of the cutting portion 200, and for the conventional double-edge twist drill, the core thickness generally accounts for about 40% of the diameter of the cutting portion 200, and the special-shaped hole drill increases the core thickness of the cutting portion 200, so that the rigidity of the cutting portion 200 is enhanced, the stability under uneven stress is improved, and the breakage accident is not easy to occur.

Secondly, four circumferential cutting edges 220 are formed on the outer circumference of the cutting part 200, and the four circumferential cutting edges 220 are simultaneously contacted with the hole wall, so that the rotation stability of the special-shaped hole drill bit is enhanced, and the circumferential cutting edges 220 can scrape the hole wall, so that burrs are cleaned, and the surface quality of the hole wall is improved.

Finally, in the conventional double-edged twist drill, two adjacent junk slots 210 do not directly intersect, in general, a margin is provided between two junk slots 210, the diameter of the margin is equal to that of the cutting portion 200, and the margin contacts with the hole wall, so that the guiding performance of the drill can be improved, but on the other hand, the friction between the margin and the hole wall also increases the cutting torque, and when the stress is uneven, the stability of the drill is easily reduced. The irregular hole drill bit reduces the contact surface between the periphery of the cutting part 200 and the hole wall by directly intersecting the adjacent chip grooves 210, thereby reducing the cutting torque and also playing the role of enhancing the stability.

From this, the stability of self when this application's dysmorphism hole drill bit can improve the earhole processing, improves the drill bit shake problem, reduces the risk of the broken sword of drill bit, and stability improves also makes processingquality improve, has reduced the burr when the earhole processing. The special-shaped hole drill bit can be suitable for micro earhole processing of a thick copper plate PCB.

In some embodiments of the present application, the comparison experiment is performed by respectively adopting the double-edge twist drill with the diameter of 0.3mm and the special-shaped hole drill for processing the earhole with the large hole diameter of 0.3mm, the breaking rate of the double-edge twist drill can be observed to reach 36% (18 pieces/50 pieces), the breaking rate of the special-shaped hole drill can be reduced to 3.85% (2 pieces/52 pieces), the appearance hole pattern of the earhole and the cutting piece quality of the hole are good, and no obvious burrs are seen. Therefore, the special-shaped hole drill bit can remarkably improve the processing yield of the earholes.

It should be noted that the chip removal capability of the special-shaped hole drill bit is reduced due to the increased core thickness, and in order to solve the problem, the special-shaped hole drill bit can process the lug holes of the PCB by adopting a segmented processing technology. Thereby avoiding the problems of drill deflection, chip resistance and the like possibly occurring during one-time processing.

For example, in some embodiments of the present application, the earhole includes two non-overlapping small holes and a large hole located intermediate the two small holes, the large hole partially overlapping the small hole. Firstly, two small holes are machined by using a common drill bit, and then a large hole is machined by replacing the common drill bit with the special-shaped hole drill bit. Taking a large hole with the depth of 3mm as an example, considering the allowance of 10%, the actual feeding distance is 3.3mm, adopting three-section processing steps of 30%, 40% and 30%, firstly controlling the special-shaped hole drill bit to drill down by 0.99mm and clear chips, then controlling the special-shaped hole drill bit to drill down by 2.31mm and clear chips, and finally controlling the special-shaped hole drill bit to drill down by 3.3mm to finish the processing of the large hole.

It can be appreciated that the chip removal capability of the core thickness increase can be reduced to a certain extent by adopting the sectional processing, but if the core thickness is too large, the chip removal groove 210 depth is too shallow, which results in further reduction of the allowable feed amount each time, and the number of sections is increased, so that the processing efficiency of the PCB is affected, and even the situation that the sectional processing cannot meet the chip removal requirement may occur. The accumulated chips may press against the sidewall of the ear hole, resulting in degradation of the processing quality of the ear hole. Thus, in some embodiments of the present application, the core thickness is 80% to 90% of the diameter of the cutting portion, by limiting the maximum value of the core thickness, thereby balancing the rigidity of the cutting portion 200 and the chip ejection capacity of the chip ejection slot 210.

In some embodiments of the present application, the walls of the junk slots 210 transition smoothly. This facilitates smooth movement of chips in the junk slots 210.

Specifically, in some embodiments of the present application, junk slots 210 include a first arc segment 211 and a second arc segment 212, the intersection of the first arc segment 211 with the end face of the drill tip forming an end face cutting edge, the second arc segment 212 intersecting the first arc segment 211 of an adjacent junk slot 210, the intersection of the first arc segment 211 and the second arc segment 212 forming a circumferential cutting edge 220.

The first arc segment 211 and the second arc segment 212 of the same junk slot 210 may be directly connected or indirectly connected, for example, referring to the embodiment of fig. 3, the junk slot 210 further includes a straight line segment 213, where the first arc segment 211, the straight line segment 213, and the second arc segment 212 are sequentially connected, and two ends of the straight line segment 213 are tangent to the first arc segment 211 and the second arc segment 212, respectively, so as to realize smooth transition of the wall surface.

In some embodiments of the present application, the radius of curvature of the first arc segment 211 is smaller than the second arc segment 212. The center of curvature of the first arc segment 211 is located inside the cutting portion 200, and the center of curvature of the second arc segment 212 is located outside the cutting portion 200. That is, the second circular arc segment 212 has a convex shape, so that the cross-sectional area of the cutting portion 200 can be increased, the rigidity of the cutting portion 200 can be increased to some extent, and the first circular arc segment 211 has a concave shape, so that the negative influence on the chip discharging capability of the chip discharging groove 210 is reduced.

The helix angle refers to the helix of the outermost edge of the chip groove 210, that is, the angle between the tangent to the circumferential cutting edge 220 and the axis of the cutting portion 200, and increasing the helix angle reduces the cutting torque and increases the chip removal capacity of the chip groove 210, but also reduces the rigidity of the cutting portion 200. Because of the greater core thickness employed in the present application, the profile hole drill bit of the present application tends to employ a greater helix angle, in some embodiments of the present application, to balance the rigidity of the cutting portion 200 with the chip removal capability of the chip flutes 210, which is 26 ° to 30 °.

Referring to fig. 4 and 5, in some embodiments of the present application, the end cutting edge comprises end primary cutting edges 230 arranged in a circumferential array.

Alternatively referring to fig. 6, in some embodiments of the present application, the end cutting edges comprise end primary cutting edges 230 and end secondary cutting edges 240 alternately arranged in the circumferential direction.

In some embodiments of the present application, the drill tip includes a chisel edge 250, the chisel edge 250 being disposed in correspondence with the main face cutting edge 230, the chisel edge 250 intersecting at the axis of the drill tip.

In some embodiments of the present application, the apex angle of the cutting portion 200 is 106 ° to 110 °. The apex angle refers to the angle between the two main cutting edges of the drill bit, and in this application, the apex angle refers to the angle between the two end main cutting edges 230. The common double-edge twist drills have a vertex angle of 118 degrees, and the special-shaped hole drill bit can be more suitable for processing soft materials of working media by adopting a smaller vertex angle, so that the special-shaped hole drill bit is suitable for processing earholes of a thick copper plate PCB.

The special-shaped hole drill bit is mainly used for processing micro earholes of a PCB, especially large holes of the micro earholes, and the processed hole diameter is basically below 0.5mm. Thus, in some embodiments of the present application, the diameter of the cutting portion 200 is less than or equal to 0.5mm.

To facilitate understanding of the technical solution of the present application, the following text describes a specific embodiment of the present application, i.e. based on a shaped hole drill, to machine ear holes in a PCB, in connection with fig. 2 to 5.

Referring to fig. 2, the total length of the shaped hole drill of the present embodiment is 38.1mm, the shaped hole drill includes a shank portion 100 and a cutting portion 200, one end of the cutting portion 200 forms a drill point, the other end of the cutting portion 200 intersects the shank portion 100, the diameter of the shank portion 100 is 3.175mm, the diameter of the cutting portion 200 is 0.3mm, and the length of the cutting portion 200 is 5mm.

Referring to fig. 3 and 4, the outer circumference of the cutting portion 200 is formed with a chip groove 210, the chip groove 210 extending spirally from the drill tip toward the shank portion 100, the helix angle of the chip groove 210 being 28 °, and the core thickness of the cutting portion 200 being equal to 80% of the diameter of the cutting portion 200.

The four chip grooves 210 are arranged along the circumferential array of the cutting portion 200, the wall surfaces of the chip grooves 210 are in smooth transition, the chip grooves 210 comprise a first arc section 211, a straight line section 213 and a second arc section 212 which are sequentially connected, two ends of the straight line section 213 are respectively tangent to the first arc section 211 and the second arc section 212, and the curvature radius of the first arc section 211 is smaller than that of the second arc section 212. The center of curvature of the first arc segment 211 is located inside the cutting portion 200, and the center of curvature of the second arc segment 212 is located outside the cutting portion 200. The first arc segment 211 and the second arc segment 212 of adjacent two flutes 210 intersect at the outer periphery of the cutting portion to form a circumferential cutting edge 220.

Referring to fig. 5, the intersection of the first circular arc segment 211 and the end face of the drill tip forms an end face cutting edge comprising end face main cutting edges 230 and end face auxiliary cutting edges 240 alternately arranged in the circumferential direction, the angle between the two end face main cutting edges 230 being 108 °. The drill tip further comprises a chisel edge 250, the chisel edge 250 being disposed in correspondence with the main face cutting edge 230, the two chisel edges 250 meeting at the axial center of the drill tip.

The working condition of this embodiment is as follows, the PCB is thick copper PCB, and thickness is 3mm, and the aperture of earhole is 0.25mm in diameter, and the macropore diameter is 0.3mm, and two apertures are tangent. In this embodiment, the ear hole is processed on the PCB according to the following steps:

step 1, processing two small holes of an earhole by using a double-edge twist drill;

step 2, replacing the double-edge twist drill with the special-shaped hole drill bit;

step 3, drilling down the special-shaped hole drill bit by 0.99mm, lifting and cleaning chips after the special-shaped hole drill bit is in place;

step 4, the special-shaped hole drill bit drills down for 2.31mm, ascends and cleans chips after the special-shaped hole drill bit is in place;

and 5, drilling 3.3mm under the special-shaped hole drill, drilling through the PCB, and processing a large hole of the earhole.

While embodiments of the present application have been shown and described, it will be understood by those of ordinary skill in the art that: many changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the application, the scope of which is defined by the claims and their equivalents.

Claims (10)

1. A shaped hole drill bit, comprising:

a handle; the method comprises the steps of,

the cutting part, the one end of cutting part forms the drill point, the other end of cutting part with the stalk portion intersects, the periphery of cutting part is formed with the chip groove, the chip groove by the drill point to the stalk portion spiral extends, four the chip groove is arranged along the circumference array of cutting part, the edge of chip groove intersects in the periphery of cutting part in order to form circumference cutting edge, the core thickness of cutting part is greater than or equal to 80% of the diameter of cutting part.

2. A shaped hole drill bit according to claim 1, wherein the core thickness is 80% to 90% of the diameter of the cutting portion.

3. A pilot hole drill bit according to claim 1, wherein the flute walls transition smoothly.

4. A shaped hole drill bit according to claim 3, wherein the junk slots comprise a first arc segment and a second arc segment, the intersection of the first arc segment with the end face of the drill tip forming the end face cutting edge, the second arc segment intersecting the adjacent first arc segment of the junk slot.

5. The shaped hole drill bit of claim 4, wherein the first arc segment has a smaller radius of curvature than the second arc segment, the first arc segment having a center of curvature that is inboard of the cutting portion and the second arc segment having a center of curvature that is outboard of the cutting portion.

6. A pilot hole drill bit according to claim 1, characterized in that the helix angle of the flutes is 26 ° to 30 °.

7. A shaped hole drill according to claim 4, wherein the end cutting edges comprise end main cutting edges arranged in a circumferential array or the end cutting edges comprise end main cutting edges and end auxiliary cutting edges alternately arranged in a circumferential direction.

8. A shaped hole drill according to claim 7, wherein the drill tip comprises a chisel edge disposed in correspondence with the main cutting edge of the end face, the chisel edge meeting at the axial center of the drill tip.

9. A shaped hole drill bit according to claim 7, wherein the apex angle of the cutting portion is 106 ° to 110 °.

10. A shaped hole drill according to claim 1, wherein the cutting portion has a diameter of less than or equal to 0.5mm.

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