CN220679467U - Spiral flute drill bit with chip breaker - Google Patents

Abstract

The application provides a spiral fluted drill bit with chip breaker, it contains cutting portion, optional direction part and optional handle of a knife, the cutting portion has the cutting edge, the cutting edge has rake face, relief surface and blade, the rake face forms a first rake in each department of blade be provided with the chip breaker on the rake face, the chip breaker is in length direction along the direction of blade, the chip breaker has the slot face that is close to the blade, thereby makes the chip breaker is close to the slot face of blade forms the second rake, the second rake is greater than corresponding first rake. The chip shape and the size of the chip are controlled through the unique chip breaker groove extending along the direction of the cutting edge, the chip size is reduced, the chip uniformity is improved, the chip discharging is facilitated, the second rake angle larger than the corresponding first rake angle is formed through the groove surface of the chip breaker groove, the sharpness of the drill is improved, the cutting resistance is reduced, and the machining efficiency is improved.

Description

Spiral flute drill bit with chip breaker

Technical Field

The utility model relates to the technical field of drill bits, in particular to a drill bit comprising chip breaking grooves.

Background

The drill bit is a hole processing cutter for forming holes in solid materials of workpieces or enlarging the existing holes, and the hole processing cutter works in the workpiece body, so that the structural size is limited, and the problems of chip holding, chip removal, strength, rigidity, guiding and the like are caused. The most widely used twist drill in the hole processing tool has the defects of longer main cutting edge, wide cutting chip and difficult chip removal of the coiled chip, and particularly, the chip removal is more difficult in deep hole processing. In order to facilitate chip removal, the chip flutes of the twist drill are usually made into a spiral shape, and in general, the smaller the helix angle of the spiral flute drill, the shorter the spiral length and the better the chip removal. But the helix angle of the spiral flute drill bit not only directly affects chip removal performance, but also is closely related to the sharpness of the cutting edge of the drill bit, the strength of the cutting edge, the overall rigidity and strength of the cutter. The smaller the helix angle is, the more convenient the chip removal is, but the smaller the cutting edge rake angle is, the cutting resistance is increased, and the cutting performance and the service life of the cutter are affected. The larger the helix angle is, the larger the cutting edge rake angle is, the cutting resistance is reduced, but the overlarge helix angle is difficult to remove chips, the cutting edge angle part is sharp, the cutting edge strength is reduced, and the chipping and the breakage are easy to occur, so that the service life of the drill bit and the quality of a processed surface are greatly reduced. The drill in the prior art cannot meet the requirements of high-end manufacturing on high-precision and high-efficiency machining of parts, so that the drill with sharp cutting edges, good chip removal and high overall strength is required to improve the cutting performance and the service life of the drill.

Disclosure of Invention

The utility model provides a drill bit comprising chip breaking grooves, which comprises the following embodiments:

embodiment 1. A drill with a helical flute comprising a cutting portion, optionally a guiding portion and optionally a shank, the cutting portion having a cutting edge and a helical flute corresponding to the cutting edge, the cutting edge having a rake face, a relief face and a cutting edge formed by the intersection of the rake face and the relief face, the rake face forming a first rake angle at each of the cutting edges, characterized in that a chip breaker is provided on the rake face, the chip breaker extending in the length direction along the direction of the cutting edge, the chip breaker having a flute face adjacent to the cutting edge such that the chip breaker forms a second rake angle adjacent to the cutting edge, the second rake angle being greater than the corresponding first rake angle, the chip breaker having a flute face remote from the cutting edge for causing the chip to be curled in the cutting direction, the chip breaker having a width of 1/20 to 1/3 of the diameter and a depth of the chip breaker of 1/10 to 1/2 of the chip breaker width.

Embodiment 2. The drill according to embodiment 1, wherein the helical groove extends into the guide portion, and the aspect ratio of the guide portion is 5 or more and 50 or less, 8 or more and 45 or less, 10 or less and 40 or less, and 15 or less and 35 or less.

Embodiment 3. The drill bit according to embodiment 1 or 2, wherein the helical groove has an angle of 0 to 30 degrees, 5 to 10 degrees, 10 to 20 degrees, or 7 to 25 degrees.

Embodiment 4. The drill according to embodiment 3, wherein the core thickness of the drill is 30% to 50%,32% to 45%,33% to 42%,35% to 40%,36% to 38% of the drill diameter.

Embodiment 5. The drill bit according to embodiment 1 or 2, wherein the drill bit having the spiral groove is made of a cemented carbide material.

Embodiment 6. The drill bit of embodiment 1, wherein the flute surfaces proximate to the cutting edge and/or the flute surfaces distal to the cutting edge are undulating surfaces.

Embodiment 7. The drill according to embodiment 1, wherein the cutting edge has a cutting edge relief, and the chip breaker groove bottom has a groove bottom relief corresponding to the cutting edge relief, so that the chip is subjected to a curling force in the direction in which the cutting edge extends.

Embodiment 8 the drill according to embodiment 7, characterized in that the cutting edge relief is wavy relief.

Embodiment 9. The drill bit according to embodiment 1 or 4, characterized in that the drill bit with helical flutes has 2 or 3 cutting edges.

Embodiment 10. The drill bit of embodiment 1, further comprising a chisel edge, wherein the chip breaker extends to the chisel edge.

Embodiment 11. The drill bit according to embodiment 1, wherein the chip breaker is manufactured by a processing method that does not cause thermal damage.

Embodiment 12. The drill bit of embodiment 1, wherein the chip breaker is prepared by a femtosecond pulse laser machining method.

Embodiment 13. A method of making the helical fluted drill according to any one of embodiments 1 to 10, wherein the helical fluted drill comprises a cutting portion, an optional pilot portion, and an optional shank, the cutting portion having a cutting edge and a helical flute corresponding to the cutting edge, the cutting edge having a rake face, a relief face, and a cutting edge formed by the intersection of the rake face and relief face, the rake face forming a first rake angle at each of the cutting edges, the method comprising:

a chip breaker is formed on the rake face, the chip breaker extending in a length direction along the direction of the cutting edge, the chip breaker having a flute face proximate the cutting edge such that the chip breaker forms a second rake angle proximate the flute face of the cutting edge, the second rake angle being greater than the corresponding first rake angle.

Embodiment 14. The method of embodiment 13, wherein the chip breaker is produced using a processing method that does not cause thermal damage.

Embodiment 15. The method of embodiment 13, wherein the chip breaker is produced using a femtosecond pulsed laser machining method.

The chip shape and the size of chip are controlled through the unique chip breaker that extends along the direction of blade, reduce the size of chip, improve the homogeneity of chip, be favorable to the chip to discharge, be close to through the chip breaker the groove face of blade forms the second rake angle that is greater than corresponding first rake angle, improves the sharpness of drill bit, has reduced cutting resistance, improves machining efficiency. The chip breaker groove is adopted to obtain a large sharpness value, the problem that sharpness is insufficient when the spiral angle is small is solved, friction between chips and workpieces is reduced due to the small spiral angle, chip removal distance is shortened, chip removal is facilitated, chip heat accumulation is avoided, and machining precision of a drill bit is improved, and service life of the drill bit is prolonged. In addition, the chip breaker design of the application can realize smooth chip removal with smaller chip removal space and shorter chip removal distance, and in deep hole machining with large length-diameter ratio, the difficult problem of chip removal can be effectively solved while the strength and rigidity of the drill bit are ensured, and the cutting performance and service life of the drill bit can be remarkably improved.

Drawings

In order to more clearly illustrate the technical solutions of the embodiments of the present disclosure, the following brief description of the drawings of the embodiments will make it apparent that the drawings in the following description relate only to some embodiments of the present disclosure, not to limit the present disclosure.

FIG. 1 is a perspective view of a drill bit according to example 1 of the present application;

FIG. 2 is a schematic view of a cutting portion of a drill bit;

FIG. 3 is an end schematic view of a drill cutting edge and chisel edge;

FIG. 4 is a partial schematic view of a cutting edge;

FIG. 5 is a schematic view of a first rake angle and a second rake angle on a cutting edge;

fig. 6 is a schematic view showing the wavy edge undulation in example 6.

Reference numerals: 100-cutting part, 110-cutting edge, 111-rake face, 112-flank face, 113-cutting edge, 10-chip breaker, 11-flute face close to the cutting edge, 12-flute face away from the cutting edge, 13-chip breaker bottom, 120-spiral flute, 130-chisel edge, 200-guide part, 300-shank.

Detailed Description

For the purpose of making the objects, technical solutions and advantages of the embodiments of the present disclosure more apparent, the technical solutions of the embodiments of the present disclosure will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present disclosure. It will be apparent that the described embodiments are some, but not all, of the embodiments of the present disclosure. All other embodiments, which can be made by one of ordinary skill in the art without the need for inventive faculty, are within the scope of the present disclosure, based on the described embodiments of the present disclosure.

The application discloses a drill bit with spiral flute, it contains cutting portion, optional direction part and optional handle, cutting portion has cutting edge and the spiral flute that corresponds with the cutting edge, the cutting edge has rake face, relief surface and the blade that is formed by the intersection of rake face and relief surface, the rake face forms a first rake at each place of blade, characterized by is provided with the chip breaker on the rake face, the chip breaker extends along the direction of blade in the length direction, the chip breaker has the groove face that is close to the blade, thereby makes the chip breaker form the second rake near the groove face of blade, the second rake is greater than corresponding first rake, the chip breaker has the groove face that is used for making the chip curl in the cutting direction, the width of chip breaker is 1/20 to 1/3 of diameter, the depth of chip breaker is 1/10 to 1/2 of chip breaker width. In some embodiments, the drill bit of the present application is free of a pilot portion and a shank, and the cutting portion has a connecting portion that combines with the circumscribing pilot portion and circumscribing shank to form a complete working drill bit. In some embodiments, the drill bit of the present application does not include a shank, the drill bit includes a cutting portion and a pilot portion having a connection that combines with an external shank to form a complete working drill bit.

Rake angle is an important geometric parameter on the tool, and the magnitude of the rake angle determines the sharpness and robustness of the cutting edge. It has a series of important effects on the cutting process. The cutting edge cutting tool has the advantages that the front angle of the cutting tool is increased, the deformation of chips can be reduced, the sharpness of the cutting edge is improved, the cutting force and the cutting power are reduced, the heat generated during cutting is reduced, and the durability of the cutting tool is improved. However, increasing the rake angle reduces the wedge angle, which reduces the blade strength and easily causes chipping; on the other hand, the heat dissipation volume of the cutter head is reduced, and the volume of the cutter head capable of containing heat is reduced, so that the cutting temperature is increased. Because ofWhen the rake angle of the tool is too large, the tool durability is also lowered. For tools made of various materials, the rake angle is too large or too small, and the tool durability is low. Under certain machining conditions, a rake angle is present at which tool durability is maximized. For a twist drill with helical flutes, the cutting edge is located at the end of the drill bit, the helical flute corresponding to the cutting edge has a helix angle ω, which refers to the angle between the tangent line of any point on the intersection line (helix line) of the outer cylinder of the drill bit with the surface of the helical flute and the drill bit axis. Let the lead of the spiral groove be P and the diameter of the outer circle of the drill bit be d ₀ Tan ω=pi d ₀ Since the radii of the points on the cutting edge are different and the leads of the points on the same spiral line are the same, the helix angles at any point on the cutting edge are different. For any point m on the cutting edge, since it is located at a diameter d _m So the helix angle omega of the helix passing through the m-point _m Can be expressed as: tan omega _m ＝d _m /d ₀ Tan ω, it can be seen that the helix angle at the outer diameter of the drill bit is greatest, the helix angle being smaller nearer the center. The helix angle is in fact the rake angle of the drill bit in the assumed working plane.

The rake angle gamma of any point on the cutting edge is measured in the orthogonal plane of that point, which is the angle between the rake surface and the base surface in the orthogonal plane, the rake angle gamma of any point m on the cutting edge _m Helix angle omega to this point _m Principal deflection angle k _rm Blade inclination angle lambda _stm The relation of (2) is: tan gamma _m ＝(tanω _m +tanλ _stm ·cosk _rm )/sink _rm . The rake angle at the outer edge of the drill is the largest, and the rake angle is smaller and negative as the drill approaches the center of the drill, and the rake angle at the drill center cannot be increased by increasing the helix angle.

It can be seen that, for the twist drill with spiral grooves, the larger the helix angle is, the larger the rake angle is, the sharper the cutting edge of the drill bit is, but the helix angle is too large, so that the strength of the cutting edge of the drill bit is weakened, the heat dissipation condition is poor, and for the drill bit with the same processing depth, the larger the helix angle is, the longer the chip removal distance is, the difficult chip removal is caused by the too large helix angle, and the processing efficiency, the processing precision and the service life of the cutter are further affected. Therefore, for the twist drill for processing holes with specific depth, smooth chip removal is realized with a smaller spiral angle, and meanwhile, the strength, toughness and sharpness of the drill bit are ensured, so that the cutting performance and the service life of the drill bit can be obviously improved.

According to the chip breaker, the chip breaker extending along the direction of the cutting edge is arranged to form the second front angle larger than the corresponding first front angle, the contradiction between chip removal, cutting edge sharpness and cutting edge strength of a drill bit with the spiral groove is effectively solved, the large front angle is realized under the condition that the spiral angle is unchanged or smaller, the sharpness of the drill bit can be improved through smaller spiral angle, cutting resistance is reduced, the sharpness value is improved, centering is stable, torsion is smaller, the drill bit is not easy to break, service life is prolonged, and the chip removal distance can be reduced through smaller spiral angle. In addition, compared with the chip breaking by only rolling the chip on the spiral surface, the chip breaking groove plays a good role in chip breaking by rolling the chip, and although the chip breaking groove is formed on the front cutter surface in the prior art so as to facilitate chip removal, the chip breaking groove cannot improve the sharpness of the cutting edge of the drill bit by a smaller spiral angle, and the chip breaking groove has the defects of difficult processing and easy damage to the cutting edge and cannot fundamentally solve the problem of difficult chip removal. The chip breaking groove controls the shape and the size of the chips through the chip breaking groove extending along the direction of the cutting edge, the chip breaking groove reduces the size of the chips through the chip breaking effect, improves the uniformity of the chips, and further reduces the chip removal distance, so that chip removal is facilitated, the strength and the heat dissipation volume of the cutting edge with a large front angle are not obviously reduced, the heat damage of the tipping edge and the surface of a workpiece is not easily caused, the cutting efficiency and the cutting precision are greatly improved, the machining precision is improved, the machining precision can be kept even under the long-time use of a cutter, and the service life of a drill bit is greatly prolonged.

The term "first rake angle" in this application is consistent with the definition of "rake angle γ" described above, which is the angle between the rake surface and the base surface in the orthogonal plane. The "second rake angle" refers to the angle between the land and the base surface in the orthogonal plane that is adjacent to the cutting edge. The base surface of any point on the cutting edge is a plane passing through the point and perpendicular to the cutting speed direction of the point. For twist drills having helical flutes, the cutting edges include a primary cutting edge, which is the intersection of the rake and relief surfaces, and a secondary cutting edge, which is the intersection of the rake and secondary relief surfaces, i.e., the edge, which is the narrow land on the outer cylindrical surface of the drill opposite the machined surface (hole wall). Unless otherwise indicated, the cutting edges in this application all refer to the main cutting edges.

The second rake angle of blade department in this application is by being close to the groove surface of blade forms, the second rake angle is greater than corresponding first rake angle, and this application adopts the form of chip breaker to obtain big sharp value promptly, makes the cutting lighter and faster, and the centering is more stable. The specific shape and size of the chip breaker can directly influence the shape and size of the chip, and the groove surface far away from the cutting edge can further curl the chip in the cutting direction, so that the chip breaker plays a role of chip breaking by the chip breaker. The width and depth ranges of the chip breaker are not limited and can generally be selected without significantly compromising the rigidity of the cutting edge. The chip breaker groove typically has a width of 1/20 to 1/3, such as 1/10 to 1/3,1/20 to 1/10,1/15 to 1/10, for example, 1/6 to 1/4 of the drill bit diameter. The depth of the chip breaker is 1/10 to 1/2, e.g. 1/8 to 1/3,1/3 to 1/2,1/6 to 1/3 of the width of the chip breaker. In this application, the width and depth of the chip breaker at each location are varied, and the term "depth of the chip breaker" refers to the depth of the entire chip breaker that is deepest relative to the rake surface, and the term "width of the chip breaker" refers to the width of the entire chip breaker that is widest in a direction perpendicular to the cutting edge.

In some embodiments, the helical groove extends into the guide portion having an aspect ratio of 5 or more and 50 or less, 8 or more and 45 or less, 10 or less and 40 or less, and 15 or less and 35 or less. Holes having a hole depth to bore diameter ratio of greater than 5 times are generally referred to as deep holes, and drill bits used for machining deep holes are generally referred to as deep holes. The drill bit provided with the chip breaking grooves is particularly suitable for deep hole drilling. Deep hole machining is different from common hole machining, and some problems are more remarkable. In deep hole processing, because the drill bit is slender, intensity and rigidity are all relatively poor, produce the vibration easily to make drilling skew and influence machining precision and productivity ratio, simultaneously, because the hole depth is big, hold bits chip removal space little, the route that the chip flows through is longer, and the chip is difficult for discharging more, and friction increases, and the cutting heat is difficult for accumulating, has increased the degree of difficulty of deep hole processing. This application is provided with deep hole drill bit of chip breaker, not only make the smear metal littleer because of the book bits chip breaking effect of chip breaker, and chip removal distance is shorter and do benefit to the smear metal and discharge, more importantly, less helix angle means that the cutting part and the direction part of drill bit that get rid of because of the helicla flute are less, the intensity and the rigidity of drill bit are improved, the second rake angle of this application depends on the setting of chip breaker, it is irrelevant with the helix angle of helicla flute, make the deep hole drill can set up less helix angle in order to guarantee higher intensity and the rigidity of drill bit under great draw ratio, satisfy chip removal demand and intensity, rigidity demand simultaneously, make deep hole processingquality and efficiency all have the improvement.

In some embodiments, the helical groove has an angle of 0 to 30 degrees, 5 to 10 degrees, 10 to 20 degrees, or 7 to 25 degrees. The smaller the spiral angle is, the smaller the friction between the chip and the workpiece is, so that the chip is conveniently removed, and the larger the spiral groove angle is, the more difficult the chip is removed. This application sets up the chip breaker that extends along the direction of blade, obtains big sharp value with the form of chip breaker, solves the problem that sharpness is not enough when spiral angle is little, and the chip removal of being convenient for simultaneously can further realize the chip removal needs of deep hole drill.

In some embodiments, the core thickness of the drill bit is 30% to 50%,32% to 45%,33% to 42%,35% to 40%,36% to 38% of the drill bit diameter. The core thickness is closely related to the rigidity and chip removal capability of the drill bit, the core thickness is large, the rigidity of the drill bit is good, but the groove area is reduced, the chip containing and removal space is reduced, and chip removal becomes difficult. High speed steel bits are used on drilling machines, with core thicknesses typically ranging from 10% to 20% of the bit diameter, with smaller diameter bits having a larger proportion, and with increasing diameter the proportion decreases. High-speed steel drill bits are highly ductile and therefore take precedence over chip removal. Whereas high-speed, high-efficiency carbide drills used in high-rigidity, high-power machining centers have a core thickness of typically 20% to 30% of the diameter, in order to increase the rigidity of the drill. This application sets up the chip breaker that extends along the direction of blade, rolls up the bits and breaks the bits through the chip breaker, makes the smear metal littleer more even, can adapt to the groove area and dwindle, under the thick circumstances of increasing of heart, holds the lower helicla flute of bits chip removal space and also can discharge the smear metal, has guaranteed when the drill bit rigidity reinforcing, and the chip removal is still unobstructed.

In some embodiments, the helical fluted drill is a monolithic cemented carbide material. The application is limited drill bit with helicla flute is whole carbide material, and whole carbide's drill bit, the preceding sword face of its cutting edge can't realize the chip breaker through the grinding, and the processing mode among the prior art also can't set up the chip breaker that extends along the blade direction, consequently can't realize the control of chip shape and size, and the chip is difficult for discharging, and can't effectively solve the problem that sharpness is insufficient when the spiral angle is little, and drill bit machining precision, machining efficiency, machining life are poor.

The cemented carbide in the present application has a general meaning understood by those skilled in the art, and is a powder metallurgical product sintered in a vacuum furnace or a hydrogen reduction furnace, wherein the cemented carbide is mainly composed of carbide (WC, tiC) micron-sized powder of a high-hardness refractory metal, and cobalt (Co) or nickel (Ni), molybdenum (Mo) as a binder. Its resistance is much higher than that of high-speed steel, about 800-1000 deg.C, and the allowable cutting speed is about 4-10 times that of high-speed steel. The hardness is very high, can reach (89-91) HRA, and can reach 93HRA; but the bending strength is 1.1-1.5 GPa, which is only half of high-speed steel; impact toughness of 0.04MJ/m ² About, it is less than 1/25 to 1/10 of that of high-speed steel. The heat resistance and the wear resistance of the cutting tool are good, so that the cutting tool has increasingly application to cutting tools with less complex edge shapes. The cemented carbide described herein comprises one selected from the group consisting of: such as tungsten-cobalt (WC-Co) cemented carbide, tungsten-titanium-cobalt (WC-Ti-Co) cemented carbide, tungsten-titanium-tantalum (niobium) cemented carbide (WC-TaC (NbC) -Co), tungsten-titanium-cobalt-tantalum (niobium) cemented carbide and the like, cemented carbide based on WC, tiC-based cemented carbide, fine-grain ultrafine-grained cemented carbide, steel cemented carbide, coated cemented carbide and the like.

In some embodiments, the land proximate the cutting edge and/or the land distal the cutting edge is a wavy undulating surface. The wavy undulating surface can further enhance the chip rolling and breaking effect of the chip breaking groove, so that chips are uniform and fine, and chip removal is facilitated.

In some embodiments, the cutting edge has a cutting edge relief and the chip breaker base has a flute base relief corresponding to the cutting edge relief, such that the chip is subjected to a crimping force in the direction of extension of the cutting edge. The cutting edge undulation increases the cutting edge length, reduces the cutting force, can prolong the service life of the cutting edge, controls the shape of the cutting chip through the undulation of the groove bottom corresponding to the cutting edge undulation in the chip breaker groove, and each undulation forms a cutting chip, so that the size of the cutting chip is further reduced, and the chip is convenient to remove.

In some embodiments, the edge relief is a wave-like relief. When the cutting edge is wavy, the rigidity is best, the stress is minimum, and the service life is longest.

In some embodiments, the helical fluted drill has 2 or 3 cutting edges. Under the condition that the chip becomes smaller through the chip breaking groove, even if the chip removal space becomes smaller, the chip can be removed better, the design with large core thickness can be adopted, the core thickness is increased, the rigidity of the drill bit is better, the problems that the three-edge drill is easy to break and the rigidity is weakened are solved, and meanwhile, the high service life advantage of the three-edge drill is exerted.

In some embodiments, the drill bit further has a chisel edge, the chip breaker groove extends to the chisel edge, so that the chip breaker groove forms a second rake angle on the cutting edge of the chisel edge, which is larger than the corresponding first rake angle, near the groove surface of the cutting edge, the sharpness of the chisel edge is improved, centering stability is facilitated, and the drill bit is particularly advantageous when applied to difficult-to-process materials.

In some embodiments, the chip breaker is prepared using a processing method that does not create thermal damage. Therefore, the chip breaker is free from a thermal damage layer, and the strength of the cutter is not degraded due to thermal damage after the chip breaker is arranged.

In some embodiments, the chip breaker groove is made using a femtosecond pulse laser machining method. The chip breaker grooves described herein may be formed using femtosecond pulse laser machining, for example, using a precision numerically controlled laser available under the trade designation LASERTEC 50 Shape from de Ma Jisen precision machine tool trade company. It is generally considered that laser forming deteriorates the properties of cemented carbide, for example, heat damage is caused by picosecond and nanosecond processing, a heat damage layer is formed at the chip breaker portion, the surface finish is extremely poor, the finishing requirements cannot be satisfied, and the service life of the tool is drastically reduced. Without being limited by theory, it is believed that the reason for this thermally damaged layer is that the oxidation of the cemented carbide, the change in microstructure in the alloy, and the reduction in hardness and wear resistance, which is evident by comparison with the life of a tool without a thermally damaged layer, is often less than half the life of a tool without a thermally damaged layer, and some even degrades to one fifth of the normal life or even less. The femtosecond pulse laser processing is adopted, the speed is extremely high, the thermal damage is not caused, the surface finish can reach the finish of 0.1-0.2nm, even a mirror surface can be realized, the chip breaking groove is suitable for finish machining, the size of the chip breaking groove is small, the mechanical property of the cutter is hardly influenced, the chip breaking problem is effectively solved, the service life of the cutter is obviously prolonged, the high-precision, high-flexibility and high-efficiency processing is realized, and the downtime of an automatic linear machine tool is reduced.

Also disclosed is a method of making the fluted drill bit, wherein the fluted drill bit comprises a cutting portion having a cutting edge and a flute corresponding to the cutting edge, the cutting edge having a rake face, a relief face and a cutting edge formed by the intersection of the rake face and relief face, the rake face forming a first rake angle at each of the cutting edges, an optional pilot portion and an optional shank, the method comprising: a chip breaker is formed on the rake face, the chip breaker extending in a length direction along the direction of the cutting edge, the chip breaker having a flute face proximate the cutting edge such that the chip breaker forms a second rake angle proximate the flute face of the cutting edge, the second rake angle being greater than the corresponding first rake angle.

The preparation methods of prior art drill bits with helical grooves are known to the person skilled in the art and comprise the following steps: 1. the shape of the drill bit with the spiral grooves is calculated according to actual needs, and a proper hard alloy bar is selected, 2. Starting from the hard alloy bar, the hard alloy bar is formed into a blank of the drill bit with the spiral grooves through grinding, 3. A semi-finished product of the drill bit with the spiral grooves is formed through finish machining grinding, 4. The semi-finished product is subjected to PVD coating treatment, and thus a finished product of the drill bit with the spiral grooves is formed.

A method for preparing the drill bit with the spiral groove mainly comprises the steps of machining chip breaking grooves on the basis of a semi-finished product, and then performing PVD coating treatment on the semi-finished product with the chip breaking grooves. In addition, the present application also provides a method of treating a helically fluted drill bit (which is junk or non-junk) comprising optionally grinding the flank of the helically fluted drill bit, then providing a chip breaker on the flank of the helically fluted drill bit, and then PVD coating the helically fluted drill bit provided with the chip breaker.

In some embodiments, the chip breaker is prepared using a processing method that does not create thermal damage.

In some embodiments, the chip breaker groove is made using a femtosecond pulse laser machining method.

The above-described ranges may be used alone or in combination. The present application can be more easily understood by the following examples.

Examples

Example 1

As shown in fig. 1 to 5, the present embodiment provides a solid carbide drill having a helical groove, which comprises a guide portion 200 of a cutting portion 100 and a shank 300, the cutting portion 100 having two cutting edges 110 and two helical grooves 120 corresponding to the cutting edges, the cutting edges having a rake face 111, a flank face 112 and a cutting edge 113 formed by the intersection of the rake face and the flank face, the rake face forming a first rake angle at each of the cutting edges, a chip breaker groove 10 being provided on the rake face, the chip breaker groove extending in a length direction along the direction of the cutting edge, and a chisel edge 130 extending onto the chisel edge, as shown in fig. 2.

Fig. 4 is a partial schematic view of one of the cutting edges, the chip breaker 10 having a flute face 11 close to the edge, a flute face 12 remote from the edge, and a chip breaker base 13, such that the flute face 11 close to the edge forms a second rake angle, which is greater than the corresponding first rake angle, the flute face 12 remote from the edge serving to cause the chip to be curled in the cutting direction.

The spiral groove extends into the guide part, the length-diameter ratio of the guide part is 5, the diameter of the drill bit is 10mm, the angle of the spiral groove is 30 degrees, the groove surface 11 close to the cutting edge and the groove surface 12 far away from the cutting edge are wavy undulating surfaces, the width of the chip breaker is 1/20 of the diameter of the drill bit, and the depth of the chip breaker is 1/2 of the width of the chip breaker.

In fig. 5, there are shown first and second rake angles formed at a point 1 near the outer edge of the cutting edge of the drill and a point 2 on the chisel edge near the center of the drill, as shown in the figure, for point 1, in orthogonal planes (O ₁ -O ₁ Plane) rake face and the basal plane are the first rake angle, the included angle b between the groove face close to the cutting edge and the basal plane is the second rake angle, the first rake angle and the second rake angle are positive angles, and the second rake angle is larger than the first rake angle. For point 2, on the edge of the chisel edge, in the orthogonal plane (O ₂ -O ₂ Plane) rake face and the basal plane are the first rake angle, the included angle d between the groove face close to the cutting edge and the basal plane is the second rake angle, the first rake angle is the negative angle, and the second rake angle is the positive angle.

The chip breaking grooves which are arranged on the front cutter surface and extend to the chisel edge form a second front angle, so that the sharpness of the cutting edge is increased, the cutting resistance is reduced, the cutting is lighter and faster, the chip breaking effect of the chip breaking grooves is realized, the chip size is reduced, the uniformity of chips is improved, chip removal is facilitated, chip heat accumulation is avoided, and the processing precision, the processing efficiency and the service life of the drill bit are improved.

Example 2

This example provides a monolithic cemented carbide drill bit with helical flutes having a diameter of 0.25mm and other features substantially identical to those of example 1.

Example 3

This example provides a solid carbide drill bit with helical flutes having a diameter of 36mm and other features substantially identical to those of example 1.

Cutting test

Hole machining tests were performed on stainless steel 316 using the solid carbide drill bits of examples 1 to 3, with the same type drill bits without chip breakers as the corresponding controls (comparative 1 to comparative 3), and the chip shapes, sizes, chip discharge were observed, and the drill bit machining lives were measured in terms of the number of drill bit machining holes, with the results shown in table 1 below:

TABLE 1

It can be seen from the table above that the arrangement of the chip breaker has obvious influence on the shape and the size of the chip, compared with the comparison, the fine chip is formed by arranging the chip breaker, the chip breaker is easy to discharge, the sharp value of the drill bit is improved by the arrangement of the chip breaker, the cutting is lighter and faster, the centering is more stable, the cutting resistance and the torsion are smaller, the drill bit is not easy to break, and the service life is prolonged.

Example 4

The present embodiment provides a solid carbide drill having a helical flute, which is substantially identical to embodiment 1, except that the helical flute has an angle of 20 degrees, and the cutting portion has three cutting edges and three helical flutes corresponding to the cutting edges.

Example 5

The present embodiment provides a solid carbide drill with spiral grooves, which is substantially identical to embodiment 1, and is different in that the angle of the spiral grooves is 20 degrees, the diameter of the drill is 0.25mm, and the groove surfaces close to the cutting edge and the groove surfaces far from the cutting edge are not provided with wavy undulations, which are flat curved surfaces extending along the direction of the cutting edge and onto the chisel edge.

Example 6

The present embodiment provides a solid carbide drill with spiral grooves, which is substantially identical to embodiment 1, and is different in that the angle of the spiral groove is 20 degrees, the diameter of the drill is 36mm, as shown in fig. 6, the cutting edge has wavy cutting edge undulation, the bottom of the chip breaker groove has groove bottom undulation corresponding to the cutting edge undulation, so that the chip is subjected to curling force in the extending direction of the cutting edge, each undulation forms a chip, and the size of the chip is further reduced, thereby facilitating chip removal.

Cutting test

Hole machining tests were performed on stainless steel 316 using the solid carbide drill bits of examples 4 to 6, with the same type drill bit without chip breaker and 30 degrees in helix angle as the corresponding control (comparative examples 4 to 6, where the cutting edge of comparative example 6 had no edge relief), and the chip shape, size, and chip discharge were observed, and the drill bit machining life was measured in terms of the number of drill bit machining holes, with the results shown in table 2 below:

TABLE 2

It can be seen from the above table that the arrangement of the chip breaker has obvious influence on the shape and size of the chip, compared with the comparison, the arrangement of the chip breaker can control the shape and size of the chip, improve sharpness, form tiny chip, and is easy to discharge. The chip breaker groove ensures the sharpness of the drill bit at a small spiral angle, so that the cutting is lighter and faster, the centering is more stable, the cutting resistance and torsion are smaller, the drill bit is not easy to break, and the service life is prolonged.

In the embodiment 4, the three-edge drill core is large, 50% and the rigidity of the drill is better, so that the problem that the three-edge drill is easy to break is solved, the processing efficiency is obviously improved, the processing service life is more than 2600, and compared with the three-edge drill of the embodiment 4, the three-edge drill core is 20% thick, and the drill is poor in rigidity and easy to break.

In example 6, wavy relief of the cutting edge and wavy relief of the groove bottom were provided, the chip size was further reduced, and the rigidity was the best, the stress was the smallest, and the life of the drill was further improved.

Example 7

The present embodiment provides a solid carbide drill bit with a spiral groove, which is a deep hole drill, and is substantially the same as embodiment 1, wherein the length-diameter ratio of the guiding portion is 10, the angle of the spiral groove is 10 degrees, and the core thickness is 30% of the diameter of the drill bit.

Example 8

The present embodiment provides a solid carbide drill bit with a spiral groove, which is a deep hole drill, and is substantially the same as embodiment 1, wherein the length-diameter ratio of the guiding portion is 30, the angle of the spiral groove is 10 degrees, and the core thickness is 30% of the diameter of the drill bit.

Example 9

The present embodiment provides a solid carbide drill bit with a spiral groove, which is a deep hole drill, and is substantially the same as embodiment 1, wherein the length-diameter ratio of the guiding portion is 50, the angle of the spiral groove is 10 degrees, and the core thickness is 30% of the diameter of the drill bit.

Cutting test

Hole machining tests were performed on 42GrMo steel using the solid carbide material deep hole drills of examples 7 to 9, with the same type drill without chip breaker and 30 degrees in helix angle as the corresponding controls (comparative 7 to comparative 9), and the chip shape, size, chip discharge were observed, and the drill machining life was measured in terms of the number of drill machining holes, with the results shown in table 3 below:

TABLE 3 Table 3

It can be seen from the table, for the deep hole drill with large length-diameter ratio, the chip breaker can be provided with a smaller spiral angle to ensure higher strength and rigidity of the drill, the chip breaker ensures the sharpness of the drill under the small spiral angle, the centering is more stable, the cutting is lighter and faster, fine chips are formed through the chip rolling and chip breaking action of the chip breaker, the chip removing distance is shortened under the smaller spiral angle, the friction between the chips and a workpiece is reduced, the chips are easy to discharge, and the chip breaker is arranged to simultaneously meet the chip removing requirement, strength and rigidity requirement of the deep hole drill. The cutting resistance and torsion of the chip breaker are smaller, the service life of the drill bit is obviously prolonged, and when the length-diameter ratio reaches 50, the processing service life is prolonged by more than 2 times compared with that of the drill bit without the chip breaker.

Example 10

This example provides a deep hole drill consistent with example 7, wherein the length-diameter ratio of the guide portion is 10, the diameter of the drill bit is 10mm, the angle of the spiral groove is 10 degrees, and the core thickness is 30% of the diameter of the drill bit.

Example 11

This embodiment provides a deep hole drill, which is different from embodiment 10 in that the length-diameter ratio of the guide portion is 30, and the core thickness is 40% of the diameter of the drill bit.

Example 12

This embodiment provides a deep hole drill, which is different from embodiment 10 in that the length-diameter ratio of the guide portion is 50, and the core thickness is 50% of the diameter of the drill bit.

Cutting test

Hole machining tests were performed on 42GrMo steel using the solid carbide material deep hole drills of examples 10 to 12, using drills of the same type without chip breaker, 30 degrees in helix angle, 30%, 20% in core thickness as the corresponding controls (comparative 10 to comparative 12), observing chip shape, size, chip discharge, and measuring the breakage rate (in per hundred pieces of breakage rate) of the drill, as shown in table 4 below:

TABLE 4 Table 4

It can be seen from the table that for the deep hole drill with large length-diameter ratio, fine chips are formed through the chip rolling and breaking action of the chip breaking groove, the uniformity of the chips is improved, the chips are easy to discharge, the deep hole drill can be provided with a smaller spiral angle and a larger core thickness, the chip removal distance is shortened by the smaller spiral angle, the friction between the chips and a workpiece is reduced, the chip removal of the deep hole drill is smooth, the rigidity and strength of the deep hole drill are enhanced by the larger core thickness, the cutting resistance and torsion are reduced by the improvement of the sharp value, the centering is stable, and the drill is not easy to break. With the improvement of the length-diameter ratio of the drill bit, the difference of the breaking rate of each hundred pieces is more obvious, when the length-diameter ratio reaches 50, the core thickness of the drill bit without the chip breaking grooves is small, the breaking rate of each hundred pieces is extremely high and reaches 50-60 pieces, and by adopting the technical scheme of the application, the cutting performance of the drill bit is improved from multiple angles, the breaking rate of each hundred pieces is extremely low and is only 12-15 pieces, the contradiction between chip removal, cutting edge sharpness and drill bit strength of the drill bit with the spiral grooves is effectively solved, and the chip removal requirement, strength and rigidity requirement of a deep hole drill are met.

The foregoing is merely exemplary embodiments of the present disclosure and is not intended to limit the scope of the disclosure, which is defined by the appended claims.

Claims (12)

1. A fluted drill with a chipbreaker comprising a cutting portion, an optional pilot portion and an optional shank, the cutting portion having a cutting edge and a flute corresponding to the cutting edge, the cutting edge having a rake face, a relief face and an edge formed by the intersection of the rake face and relief face, the rake face forming a first rake angle at each of the edges, characterized in that,

a chip breaker is provided on the rake face, the chip breaker extending in the longitudinal direction in the direction of the cutting edge, the chip breaker having a flute face adjacent the cutting edge such that the flute face of the chip breaker adjacent the cutting edge forms a second rake angle, the second rake angle being greater than the corresponding first rake angle, the chip breaker having a flute face remote from the cutting edge for causing chips to be curled in the cutting direction,

the width of the chip breaker is 1/20 to 1/3 of the diameter of the drill bit, and the depth of the chip breaker is 1/10 to 1/2 of the width of the chip breaker.

2. The fluted drill with a chip breaker according to claim 1, wherein the flutes extend into the pilot section having an aspect ratio of 5 or more to 50 or less, 8 or more to 45 or less, 10 or more to 40 or less, and 15 or more to 35 or less.

3. The fluted drill bit with a chipbreaker according to claim 1 or 2, wherein the flute angle is 0 to 30 degrees, 5 to 10 degrees, 10 to 20 degrees, or 7 to 25 degrees.

4. A fluted drill bit according to claim 3, wherein the core thickness of the bit is 30% to 50%,32% to 45%,33% to 42%,35% to 40%,36% to 38% of the bit diameter.

5. The fluted drill bit according to claim 1 or 2, wherein the fluted drill bit is of cemented carbide.

6. The fluted drill bit according to claim 1, wherein the flute face proximate to the cutting edge and/or the flute face distal to the cutting edge is a wavy undulating surface.

7. The fluted drill with flutes according to claim 1, wherein the cutting edges have cutting edge undulations and the flute bottoms have flute bottom undulations corresponding to the cutting edge undulations, such that the chips are subjected to a curling force in the direction of extension of the cutting edges.

8. The fluted drill with chipbreaker of claim 7 wherein the cutting edge relief is a wave relief.

9. The fluted drill bit according to claim 1 or 4, wherein the fluted drill bit has 2 or 3 cutting edges.

10. The fluted drill bit of claim 1 further having a chisel edge, the flutes extending onto the chisel edge.

11. The fluted drill bit of claim 1 wherein the flutes are formed by a process that does not produce thermal damage.

12. The fluted drill bit of claim 1 wherein the flutes are formed by a femtosecond pulsed laser machining process.