CN213496731U

CN213496731U - Back drill bit

Info

Publication number: CN213496731U
Application number: CN202022009453.4U
Authority: CN
Inventors: 杨令; 张辉; 卢成; 何先友
Original assignee: Shenzhen Jinzhou Precision Technology Corp
Current assignee: Shenzhen Jinzhou Precision Technology Corp
Priority date: 2020-09-15
Filing date: 2020-09-15
Publication date: 2021-06-22
Anticipated expiration: 2030-09-15

Abstract

The utility model is suitable for a deep hole back drilling technique discloses a back drilling drill point, including drillstock and work portion, the rear end and the drillstock of work portion are connected, the outer peripheral face of work portion is provided with two chip removal owner grooves about the symmetry of work portion center, two chip removal owner grooves extend and cross in a bit from the work portion front end towards the rear end with the heliciform, two chip removal owner grooves intersect respectively with the front end terminal surface of work portion and obtain two cutting edges, contained angle is 115-125 between the back knife face of two cutting edges, the inner of two cutting edges of intersection line connection of two cutting edges of two cutting edge behind the cutting edge forms the chisel edge, the length of chisel edge is 0.02-0.18mm, the outer peripheral face of work portion still is provided with two at least follow intersection point to the side by side chip auxiliary groove of spiral extension of work portion rear end. The utility model provides a pair of back drilling drill point, it can improve the bad and inclined to one side hole problem of hole shape that multilayer circuit board back drilling deep hole machining appears, satisfies customer user demand.

Description

Back drill bit

Technical Field

The utility model belongs to the technical field of the deep hole back drilling, especially, relate to a back drilling drill point.

Background

The back drilling process is to drill NPTH holes with certain depth requirement on some PTH holes by using a drill with a larger diameter by using the depth control function of a mechanical drilling machine so as to remove through hole sections which do not play any connection or transmission role, avoid causing reflection, scattering, delay and the like of signal transmission and bring distortion to signal transmission. With the development of communication PCBs, the back drilling machining depth is deeper and deeper, and back drilling holes with the depth exceeding 3 mm are common, so that the back drilling difficulty is higher and higher. The problem of the hole shape is bad can appear in current back drilling drill point when carrying out the degree of depth processing, and the S hole shape that also we often say, because the hole shape is bad too big (the height point difference exceeds 20um), the tangent risk of back drilling exists in the back drilling inner circuit that is close to mutually, brings very big hidden danger for PCB model transmission, also can bring the quality problems such as inclined to one side hole simultaneously, and high-end PCB manufacturing enterprise also attaches attention to this type of quality problem. There is a strong need for a back-drilling drill point to solve this problem.

SUMMERY OF THE UTILITY MODEL

The utility model discloses aim at solving one of above-mentioned technical problem at least, provide a back-drilling drill point, it can improve the bad and inclined to one side hole problem of hole shape that multilayer circuit board back-drilling deep-hole machining appears, satisfies customer user demand.

The technical scheme of the utility model is that: the utility model provides a back drill point, includes drillstock and working portion, the rear end of working portion with the drillstock is connected, the outer peripheral face of working portion is provided with two about the chip removal owner groove of working portion center symmetry, two the chip removal owner groove is followed with the heliciform the working portion front end extends towards the rear end and crosses in a point, two the chip removal owner groove respectively with the front end terminal surface of working portion intersects and obtains two cutting edges, two contained angle is 115-125 between the back knife face of cutting edge, two the intersection line of cutting edge back knife face connects two the inner of cutting edge forms the chisel edge, the length of chisel edge is 0.02-0.18mm, the outer peripheral face of working portion still be provided with two at least from the intersection point to the chip removal auxiliary tank that the working portion rear end spirally extended side by side.

Optionally, the depth of the chip discharge auxiliary groove gradually decreases from the intersection point to the rear end of the working part.

Optionally, the helix angle of the primary flutes is 40 °.

Optionally, the distance from the front end of the working portion to the junction is 0.4-1.6 mm.

Optionally, the distance from the front end of the working portion to the junction is 0.8-1.2 mm.

Optionally, the helix angle of the chip ejection sub-groove is 40-60 °.

The utility model provides a pair of back drilling drill point, optimize the size of apex angle and the length of chisel edge, compare with current back drilling drill point, its chisel edge length and apex angle diminish, through the integration design between them, the stability of drill point drilling has been improved, and chisel edge length shortens, make the flank width increase, the wear resistance of drill point has been improved, and simultaneously, two chip removal owner grooves cross in a bit, and set up two at least chip removal auxiliary flutes side by side behind the junction, so design, guarantee the superelevation chip removal ability of drill point on the one hand, prevent that the smear metal from blockking up at the drill point portion, on the other hand, can ensure the rigidity intensity of working part behind the junction, avoid the drilling course of working, avoid the working part shake or incline to appear effectively, solve current drill bit and carry out the bad problem of S hole shape that deep hole back drilling processing appears.

Drawings

In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the drawings needed to be used in the embodiments will be briefly described below, and it is obvious that the drawings in the following description are only some embodiments of the present invention, and it is obvious for those skilled in the art that other drawings can be obtained according to these drawings without creative efforts.

Fig. 1 is a schematic structural diagram of a back drill bit according to an embodiment of the present invention;

FIG. 2 is a right side view of FIG. 1;

fig. 3 is a schematic structural view of a conventional backdrilling drill bit.

In the figure, 1-drill handle, 2-working part, 3-chip removal main groove, 4-intersection point, 5-cutting edge, 6-horizontal edge, 7-chip removal auxiliary groove, D-edge surface width, L-horizontal edge length, alpha-vertex angle, beta-chip removal auxiliary groove helix angle, gamma-chip removal main groove helix angle, 3 ' -chip removal groove of the existing back drill needle, alpha ' -vertex angle of the existing back drill needle and gamma ' -helix angle of the chip removal groove of the existing back drill needle.

Detailed Description

In order to make the objects, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.

It should be noted that the terms "disposed" and "connected" should be interpreted broadly, and may be, for example, directly disposed or connected, or indirectly disposed or connected through intervening elements or intervening structures.

In addition, in the embodiments of the present invention, if there are terms of orientation or positional relationship indicated by "longitudinal", "transverse", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc., it is based on the orientation or positional relationship shown in the drawings or the conventional placement state or use state, and it is only for convenience of description and simplification of description, but does not indicate or imply that the structures, features, devices or elements referred to must have a specific orientation or positional relationship, nor must be constructed and operated in a specific orientation, and therefore, should not be construed as limiting the present invention. In the description of the present invention, "a plurality" means two or more unless otherwise specified.

The various features and embodiments described in the detailed description may be combined in any suitable manner, for example, different embodiments may be formed by combining different features/embodiments, and various combinations of features/embodiments are not separately described in order to avoid unnecessary repetition in the present disclosure.

As shown in FIG. 1 and FIG. 2, the embodiment of the utility model provides a back drill point for the back drilling processing that the aperture is 0.15-0.6mm, especially in deep hole back drilling processing field, can reduce the hole shape defective rate (the probability that S appears the hole shape) of back drilling and improve the hole site precision. The drill bit comprises a drill handle 1 and a working part 2, wherein the drill handle 1 is used for holding the drill bit on the main shaft of the machine tool, relative to the working part 2, the drill handle 1 is connected to the rear end of the working part 2, the outer peripheral surface of the working part 2 is provided with two main chip removal grooves 3 which are symmetrical relative to the center of the working part 2, the two main chip removal grooves 3 extend from the front end to the rear end of the working part 2 in a spiral shape and are converged at one point, the two main chip removal grooves 3 are respectively intersected with the front end surface of the working part 2 to obtain two cutting edges 5, the two cutting edges 5 are main cutting parts of the drill bit, the included angle between the rear cutter surfaces of the two cutting edges 5 is 115-125 degrees, namely the vertex angle alpha of the drill bit is 115-125 degrees, the intersection line of the rear cutter surfaces of the two cutting edges 5 is connected with the inner ends of the two cutting edges 5 to, the length L of the chisel edge 6 is 0.02-0.18mm, and the peripheral surface of the working part 2 is also provided with at least two chip removal auxiliary grooves 7 which spirally extend from the intersection point 4 to the rear end of the working part 2 side by side. Compare with current back drilling drill point, the utility model discloses an its apex angle of back drilling drill point diminishes, the chisel edge shortens, through the combination to apex angle size and chisel edge length, has strengthened the sharpness of drill point and improved the stability of drill point drilling, and chisel edge length shortens moreover, can make cutting edge face width D increase, has improved the wear resistance of drill point. Meanwhile, the two main chip removal grooves are converged at one point, at least two side-by-side chip removal auxiliary grooves are arranged behind the convergence point, and chips generated by the cutting edge 5 during cutting are converged at the convergence point 4 and are discharged by the chip removal auxiliary grooves 7. Design like this, guarantee the chip removal ability of boring point department on the one hand, prevent that the smear metal from blockking up at the point of boring, on the other hand can ensure the rigidity intensity of working part behind the meeting point, avoids the drilling course of working, avoids drill point department to appear shake or incline effectively, solves the current drill bit and carries out the bad problem of S hole shape that deep hole back drilling processing appears, satisfies the preparation of high accuracy requirement PCB board for the signal can be quick in PCB, high efficiency, accurate transmission.

Optionally, the depth of the chip removal auxiliary groove 7 is gradually reduced from the intersection point 4 to the rear end of the working part 2, that is, the core thickness of the working part 2 is larger as the drill shank 1 is closer, the core diameter of the working part behind the intersection point is in a forward-cone structure, and the rigidity strength of the working part is further improved.

Specifically, the number of the chip removal auxiliary grooves 7 can be determined according to the actual cutting speed, for example, two, three, four, etc., and only the front end of each chip removal auxiliary groove 7 needs to be connected to the junction 4, so that the chips can be quickly discharged, and the chips are prevented from blocking the back drilling hole in the high-speed cutting process.

Optionally, the helix angle γ of the two chip removal main grooves 3 is 40 °, and the dimensional tolerance is ± 3 °.

Alternatively, the distance from the front end of the working part 2 to the junction 4 may be 0.4-1.6mm, if the distance from the front end of the working part 2 to the junction 4 is less than 0.4mm, the chips may be easily accumulated in the chip removal main groove, which is not favorable for chip removal, and if the distance from the front end of the working part 2 to the junction 4 is greater than 1.6mm, the rigidity strength of the working part may be affected, which may easily cause the drill tip to shake or deflect.

Specifically, the distance from the front end of the working part 2 to the junction 4 may be 0.8-1.2 mm.

Optionally, the helix angle beta of the chip removal auxiliary groove 7 can be 40-60 degrees, and under the condition of ensuring the rigidity of the drill body, the helix angle beta of the chip removal auxiliary groove 7 is optimized, so that chips can be favorably discharged from the hole.

In particular, the helix angle of the debris ejection sub-grooves may be 45 °.

The embodiment of the utility model provides a back drill point, on the one hand, optimize the size of apex angle alpha and the length L of chisel edge, compare with current back drill point, its chisel edge length L shortens, apex angle alpha diminishes, through the design of fusing between the two, the corresponding stability that has improved the drill point drilling, and chisel edge length L shortens for cutting face width D increases, has improved the wear resistance of drill point; on the other hand, make two chip removal owner grooves 3 meet in a point, and be provided with two at least chip removal auxiliary flutes 7 side by side behind the meeting point 4, and the degree of depth of chip removal auxiliary flute 7 diminishes gradually towards the direction of 2 rear ends of work portion 4 at the meeting point, make the core footpath of work portion 2 be in the same direction as the awl structure, both guaranteed the superhigh chip removal ability of drill point, prevent that the smear metal from blockking up at the drill point portion, can ensure the rigidity intensity of work portion 2 behind meeting point 4 again, avoid the drilling course of working, avoid the work portion shake or incline to appear effectively, solve the current drill bit and carry out the bad problem of S hole shape that deep hole back drilling processing appears.

In order to better embody the effects of the present invention, the following description is made with reference to specific embodiments:

example 1

Control group: in the conventional drill point, the vertex angle alpha ' is 130 degrees, the length of a cross edge is 0.2mm, and the helical angle gamma ' of a chip groove 3 ' is 25 degrees; (two flutes extending helically, without meeting point)

Experimental group 1: the drill point of the utility model has a vertex angle alpha of 115 degrees, a horizontal blade 6 of 0.15mm in length, a helix angle gamma of a chip removal main groove 3 of 40 degrees, an intersection point 4 of 0.5mm away from the front end of a working part 2, two chip removal auxiliary grooves 7 and a helix angle beta of 40 degrees;

experimental group 2: the drill point of the utility model has a vertex angle alpha of 120 degrees, a cross edge 6 with a length of 0.1mm, a helix angle gamma of a chip removal main groove 3 of 40 degrees, an intersection point 4 with a distance of 0.65mm from the front end of a working part 2, two chip removal auxiliary grooves 7 and a helix angle beta of 40 degrees;

experimental group 3: the drill point of the utility model has a vertex angle alpha of 125 degrees, a horizontal blade 6 of 0.08mm in length, a helix angle gamma of a chip removal main groove 3 of 40 degrees, an intersection point 4 of 0.8mm away from the front end of a working part 2, two chip removal auxiliary grooves 7 and a helix angle beta of 40 degrees;

the experimental conditions were the same: machine tool equipment: SCHMOOL (depth control function), back-drilling drill point working diameter is 0.04mm, spindle speed: 85KRPM, feed amount: 1.8m/min, tool retracting speed: 20m/min, back drilling times: 400 holes, processing materials: high-speed material multiply wood, the thick 3.8mm of board, back drilling depth of processing: shallow hole 0.20mm, deep hole 2.4 mm.

Shallow hole processing, the back drilling depth is 0.20mm, and the specific conditions are as follows in table 1:

TABLE 1

From the data in table 1, when the back drilling processing of shallow holes is performed, the back drilling needles corresponding to the control group, the experimental group 1, the experimental group 2 and the experimental group 3 have low probability of having poor hole shape, hole blockage and hole deviation, and the difference between the hole shape poor rate, the hole blockage rate and the hole deviation rate is relative.

Wherein, the hole shape defective rate refers to: in the cross section of the back drilling hole obtained by processing, two boundaries of the back drilling hole are in an S-shaped curve structure relative to the central axis of the back drilling hole, and the S hole value refers to the difference value between the highest peak and the lowest valley in the S-shaped curve, and in the field, the back drilling hole with the S hole value of less than 12 microns can meet the requirement.

By offset is meant that the axes of the backdrilled hole and the via hole do not coincide.

Deep hole processing, the back drilling depth is 2.4mm, and the specific conditions are as follows in table 2:

TABLE 2

From the data in table 2, when deep hole back drilling is performed, the back drilling drill points in the control group are processed, the S-hole value of the back drilling holes obtained by processing does not meet the requirement, and the back drilling drill points corresponding to the experimental group 1, the experimental group 2 and the experimental group 3 have poor hole shapes, and have lower probability of hole plugging and hole deviation than the back drilling drill points in the control group, that is, the back drilling drill points corresponding to the experimental group 1, the experimental group 2 and the experimental group 3 are superior to the back drilling drill points in the control group. Therefore, the back drilling drill points corresponding to the experimental group 1, the experimental group 2 and the experimental group 3 can be used for back drilling processing of shallow holes and deep holes.

The above description is only exemplary of the present invention and should not be taken as limiting the scope of the present invention, as any modification, equivalent replacement or improvement made within the spirit and principle of the present invention should be included in the present invention.

Claims

1. The utility model provides a back drill point, includes drillstock and work portion, the rear end of work portion with the drillstock is connected, its characterized in that, the outer peripheral face of work portion is provided with two about the symmetrical chip removal owner's groove in work portion center, two the chip removal owner's groove is followed with the heliciform the work portion front end is extended towards the rear end and is intersected in a point, two the chip removal owner's groove respectively with the front end terminal surface of work portion intersects and obtains two cutting edges, two the contained angle is 115-125 between the back knife face of cutting edge, two the intersection line of cutting edge back knife face is connected two the inner of cutting edge forms the chisel edge, the length of chisel edge is 0.02-0.18mm, the outer peripheral face of work portion still be provided with two at least from the intersection to the vice groove of chip removal that the spiral extends side by side in work portion rear end.

2. A back drill bit according to claim 1, wherein the depth of the chip ejection sub-groove gradually decreases from the intersection towards the rear end of the working portion.

3. A back drill bit as claimed in claim 1, wherein said primary flutes for chip removal have a helix angle of 40 °.

4. A back drill bit according to claim 1, wherein the distance from the front end of the working portion to the junction is 0.4-1.6 mm.

5. A back drill according to claim 4, wherein the distance from the front end of the working portion to the junction is 0.8-1.2 mm.

6. A back drill bit as claimed in claim 1, wherein the helix angle of the chip evacuation sub-flutes is between 40 ° and 60 °.