122 results about "Rake angle" patented technology

In one aspect of the present invention, a drill string has a drill bit with a body intermediate a shank and a working face. The working face has a plurality of blades converging at a center of the working surface and diverging towards a gauge of the working face. At least one blade has a cutting element with a carbide substrate bonded to a diamond working end with a pointed geometry. The diamond working end also has a central axis which intersects an apex of the pointed geometry. The axis is oriented between a 25 and 85 degree positive rake angle.

The invention discloses a formed milling cutter tool system for machining a jaw and a machining method. The formed milling cutter tool system comprises a formed milling cutter. The forming milling cutter comprises a milling cutter disc body, a cutter shaft mounting hole formed in the position of the central axis of the milling cutter disc body, a plurality of composite-shape cutting teeth arranged on the outer circle of the milling cutter disc body and arranged at intervals in the circumferential direction, and tooth grooves formed between every two adjacent composite-shape cutting teeth in the circumferential direction. The composite-shaped cutting teeth are provided with shovel rear angles in the circumferential direction. Each composite-shape cutting tooth comprises a main cutting tooth part, a transition cutting tooth part and an auxiliary cutting tooth part which are adjacently connected in the axial direction, and each main cutting tooth part comprises a section of sawtooth-shaped dense teeth, a section of sawtooth-shaped comb teeth and a section of linear teeth which are adjacently connected in sequence in the axial direction; a special milling cutter for dense tooth part machining and a dense tooth part on-line strong cold abrasion monitor are further arranged in a matched mode. The invention provides a systematic solution integrating a special cutter, online wear monitoring and auxiliary forced cooling.

The application discloses a threaded hole machining method for a titanium rod, the threaded hole is arranged on a working section of the titanium rod, and the working section is made of titanium alloy material; the threaded hole machining method comprises the following steps: S1, a tungsten steel drill bit is selected to process a bottom hole with a preset size at one end of a workpiece to be machined; S2, a boring tool is used to bore the bottom hole to empty titanium slag debris in the bottom hole; S3, after the titanium slag debris in the bottom hole is emptied, a tapping tap is used to tap the bottom hole to form a threaded hole; wherein the tapping tap has a 30-35 degree rake angle and a 40 degree relief angle; S4, the threaded hole is bored by the boring tool to remove burrs left at the bottom of the threaded hole; the steps S3 and S4 are repeated until the inner thread specification of the threaded hole is #10-32UNF-2B, #10 is a number, 32 is a number of teeth, UNF represents fine thread, and 2B is the accuracy grade of the inner thread. The threaded hole machining method can reduce part rejection and improve the quality of the threaded hole.

The utility model discloses a single crystal diamond forming milling cutter for aluminum alloy processing, which comprises a cutter handle part made of an alloy material, a blade mounting part made of an alloy material is arranged at the front end of the cutter handle part, and the blade mounting part is of a wedge-shaped structure; the first wedge-shaped surface of the wedge-shaped structure is perpendicular to the second wedge-shaped surface; a single crystal diamond blade is arranged on the second wedge-shaped surface; the single crystal diamond blade is of a second wedge-shaped structure matched with the half outer contour of the second wedge-shaped face. A first machining inclined plane is arranged at the top of the second wedge-shaped structure, and a first machining plane is arranged at the tail end of the second wedge-shaped structure; the first machining inclined surface and the first machining plane are connected through a second machining inclined surface and a first machining vertical surface; the first machining slope is provided with a first axial rake angle and a second axial rake angle. According to the utility model, the sharpness and the service life are both considered, and meanwhile, the high-quality processing of an aluminum alloy (AL6063) material can be completed.

The utility model relates to an enclosed hair trimming cutter head and a shaving tool, which are characterized in that each movable cutter tooth in a movable cutter is provided with a front angle and a rear angle, the motion trail of the front angle of each movable cutter tooth penetrates through a hair guide groove, and the motion trail of the rear angle of each movable cutter tooth is positioned outside the closed end of the hair guide groove; when the movable cutter teeth approach to any static cutter tooth, a first included angle S1 is formed between the movable cutting edge and the static cutting edge on the corresponding static cutter tooth, when the front angle of the movable cutter teeth makes contact with the static cutting edge, an enclosed space with the periphery closed temporarily is defined in the hair guide groove, and when the rear angle crosses the static cutting edge, all hair in the enclosed space is cut off. The utility model has the beneficial effects that when the movable cutter is driven by external force to move along the static cutter to enable the movable cutter teeth to approach any static cutter tooth in the static cutter, a first included angle S1 is formed between the movable cutting edge and the static cutting edge, and when the front angle is in contact with the static cutting edge, an enclosed space with a closed periphery can be enclosed in the hair guide groove under the matching of the movable cutting edge and the static cutting edge; the hair is limited in the enclosed space, so that the hair is effectively prevented from escaping from the hair guide groove.

A rotary cutting method includes producing a processed product by rotary cutting of a workpiece by a rotary tool. The rotary tool has at least one cutting edge of which both of a first rake angle in a rotation radial direction and a second rake angle in a rotation axis direction are negative. The at least one cutting edge has a slanted face connected with a rake face forming the first and second rake angles. The slanted face is connected with the rake face at a ridge line. The slanted face faces a rotating direction of the rotary tool. An angle of the slanted face to the rotation axis direction is positive.

The utility model provides titanium alloy plate rough milling cutter blade and titanium alloy plate rough milling cutter, and the negative chamfer is provided with to the side surface transition direction of cutting edge, when the diameter of blade body is 20mm, the width of negative chamfer is 0.42~0.62mm, when the diameter of blade body is greater than 20mm or is less than 20mm, the width of negative chamfer is increased or reduced according to the proportion of blade body diameter, and is increased or reduced in equal proportion, the rake face of blade includes first rake face and second rake face, and the included angle of first rake face and second rake face with base surface is first rake angle and second rake angle respectively, and first rake angle and second rake angle are all greater than 0 DEG. The utility model sets up the negative chamfer of wider, strengthens the strength of cutting edge, sets up two rake faces, and two rake angles are all greater than 0 DEG, first rake face is used for strengthening the strength of cutting edge, second rake face is used for reducing the chip force, makes the blade not only has higher strength, also has good sharpness, and the service life of blade is greatly improved.

The utility model belongs to the technical field of cutters, and discloses an end mill, which is characterized in that bottom blades are distributed on a revolution surface formed by rotation of a 1 / 4 ellipse around a central axis of a cutting part, so that a tool cutting edge angle is gradually and slowly increased in the direction from the center of the end mill to the periphery of the end mill, and one end, connected with a circumferential blade, of each bottom blade can also be used for cutting. And under the same cutting depth, cuttings become thinner and longer, and the thinning cutting effect is better during fast feeding, so that the machining efficiency of difficult-to-machine materials such as titanium alloy and high-temperature alloy is improved. The end, connected with the circumferential edge, of the bottom edge is used for increasing the maximum cutting depth after cutting, and the front angle corresponding to the bottom edge is gradually increased in the radial direction, away from the central axis of the cutting part, of the cutting part, so that the end, close to the circumferential edge, of the bottom edge is sharper, cutting resistance is reduced, cutting force and cutting heat are reduced, and the wear resistance of the cutter is improved; and the service life of the cutter is prolonged.

The utility model relates to a rotary shaving cutter, a trimming cutter head and a trimming tool, which are characterized in that at least one movable cutter tooth is provided with a front angle and a rear angle, and the vertical distance T between the front angle and the rear angle is smaller than the length of a hair guide groove in a static cutter, so that the outer rotating track of the front angle and the inner rotating track of the rear angle are both positioned in the hair guide groove of the static cutter; and when the front angle is close to any hair guide groove in any static cutter, the movable cutting edge and the static cutting edge are inclined to form a first included angle S1. The utility model has the beneficial effects that the positions of the front angle and the rear angle of the movable cutter tooth are mutually adjusted, when the front angle of the movable cutter tooth is in contact with the static blade of the static cutter tooth, the front angle of the movable cutter tooth and the static blade form a closed state, and at the moment, even if part of to-be-sheared beards and other hairs are extruded by the static blade and the static blade, the hairs can be sheared off. When the trimming tool moves, the trimming tool can slide out of the trimming area of the movable blade and the static blade from the rear corner below and the opening of the static blade, so that the galling phenomenon at the moment of moving of the trimming tool can be prevented, and the use comfort of the trimming tool is improved.

This invention relates to a method for regrinding fir tree-shaped end mills, including checking the sharpness and diameter wear of the end mill to determine the regrinding method; rake angle regrinding, using a grinding wheel to regrind the rake angle of the fir tree-shaped end mill; or clearance angle + rake angle regrinding, using a grinding wheel to regrind both the clearance angle and rake angle of the fir tree-shaped end mill. This invention also relates to a method for machining fir tree-shaped tenons using a fir tree-shaped end mill, including checking the end mill, determining the machining method, and performing one-pass machining or two-pass machining. This regrinding method increases the number of regrinding cycles for the fir tree-shaped end mill, extending its service life by 3-4 cycles and reducing the cost of the fir tree-shaped end mill by 20%. This machining method ensures the machining accuracy of the fir tree-shaped tenons.

The application discloses a variable rake angle insert gear dry cutting hob, which is characterized by comprising a cutter shaft and a plurality of inserts, the outer surface of the cutter shaft is provided with a spiral body for insert installation in the circumferential direction, and the plurality of inserts are detachably inserted into the spiral body; the inserts are provided with a rake face and a relief face, and the rake face and the relief face are both twisted to make the rake angle of the cutting edge unequal everywhere; the inclination of the tooth profile in gear machining can be reduced, the strength of the gear tooth is enhanced, the problems of uneven cutting wear in hobbing machining and poor contact of the gear tooth with a small spiral angle after hobbing machining are solved, gear meshing precision is improved, and in addition, the overall cost of the hob can be reduced by adopting the insert structure, the detachable connection mode is beneficial to the individual replacement of the worn inserts, and the whole hob is not scrapped.

The invention discloses a deep-cavity small-structure part manufacturing and machining method, and belongs to the technical field of machining. Comprising turning, polishing and cleaning; for a structure with an arc surface in a deep cavity of the part, a tool for turning is a tool with a front angle of 5-15 degrees; polishing is conducted after turning, rough polishing, semi-fine polishing and fine polishing are sequentially adopted for polishing, and cleaning is conducted after each time of polishing; in the polishing step, a polishing rod with cloth fixed at the front end is adopted, an abrasive is sprayed on the cloth, and the polishing rod and the center of the part are staggered and rotate oppositely for polishing; according to the invention, turning-polishing-cleaning full-closed-loop manufacturing is realized; the precision of a deep-cavity small-structure part is improved, the problem of sealing failure of an aerospace / medical valve body under the extreme working condition (-80 DEG C) is solved, and the one-time delivery inspection percent of pass is improved to be larger than or equal to 98%.

The utility model relates to the technical field of machining, and discloses a side face machining cutter which comprises a cutter bar. The cutter head is arranged at the end part of the cutter bar; a plurality of spirally arranged blade parts are arranged on the tool bit, front angles are arranged on cutting edges of the blade parts, and negative chamfers are formed; a cutting edge of the cutting edge part is provided with an edge tip end, and a negative chamfer and a relief angle group are respectively formed on two opposite sides of the edge tip end; according to the utility model, the front angle is arranged on the cutting edge part and the negative chamfer is formed, so that the side face finish machining or mirror surface machining of a material can be realized, the time and the cost of subsequent procedures are reduced, the overall structure has higher strength and machining precision, and the machining efficiency of actual machining application can be ensured.

This invention discloses a method for solving the grinding trajectory of helical grooves in a conical end mill. Specifically, the method involves: first, defining the process characteristics of the helical groove, including modeling the tool's helical cutting edge, defining tool parameters, and modeling the grinding wheel's grinding motion; second, establishing the solution equation for the grinding wheel's pose based on the tool parameters; and finally, using a particle swarm optimization algorithm to solve for the grinding wheel's pose. This invention can be effectively used for machining helical grooves, simultaneously meeting the machining accuracy requirements of the rake angle and core diameter, and providing a theoretical reference for the actual production and machining of cutting tools.

A one-piece cutting head for a drill bit includes a main cutting edge that extends between radial extremities of the cutting head. The main cutting edge is disposed between main rake surfaces and main relief surfaces. Each main rake surface includes one or more rake facets, and each main relief surface includes one or more relief facets. Adjacent rake facets and relief facets define a primary transverse edge therebetween that extends away from the main cutting edge. The cutting head further includes a plurality of side cutters that are transverse to the main cutting edge and that propagate from the primary transverse edge to a radial extremity of the cutting head. Each side cutter includes a side cutting edge between a side cutting rake facet and a side cutting relief facet.

The drilling cutter is applied to the field of machining and comprises a cutter handle, a cutter body is arranged at one end of the cutter handle, a drill tip is arranged at the end, away from the cutter handle, of the cutter body, a main cutting edge, an end edge and a chisel edge are arranged on the drill tip, and a G-shaped chip containing groove is formed in the drill tip. The drilling tool has the technical effects that in the machining process of the drilling tool, the drill tip plays a key centering role, the positive rake angle is formed at the drill tip through the design of the G-shaped chip containing groove, and as the linear speed at the absolute center of the drill tip is zero, when the drill tip is just in contact with a part, extrusion caused by machining has great damage to a drill core of the drill tip; the positive rake angle can play a cutting role when the main cutting edge drills, independent chip breaking is completed in the G-shaped chip containing groove, meanwhile, the sharpness of the chisel edge is enhanced, drill core abrasion of the drill tip is relieved, the service life of a cutter is prolonged, and the drilling efficiency and the production quality are improved.

The invention belongs to the technical field of milling, and discloses a milling workpiece surface topography prediction method considering multi-factor influence, which comprises the following steps: considering a tool rake angle geometric parameter, establishing a milling force model, and calculating a shear force coefficient and a tillage force coefficient; a tool vibration displacement model is established, a generalized RKN4 method is adopted, a second-order motion differential equation of the tool vibration displacement model is directly solved, and the vibration displacement solving speed is increased; establishing a workpiece deformation model, and applying a node division method to workpiece deformation calculation; and establishing a surface topography prediction model, and generating a workpiece surface topography matrix by adopting a Z-map method. According to the milling workpiece surface topography prediction method considering the multi-factor influence, the geometric parameters of the front angle are considered, and accurate prediction of the milling force is achieved; a generalized RKN4 method is adopted, so that the vibration displacement solving efficiency is improved; influences of tool vibration displacement and workpiece deformation on the surface topography are comprehensively considered, and accurate prediction of the surface topography is achieved.

Provided is a circular saw blade capable of improving chipping resistance of a cutting edge and improving discharging performance of cutting chips.　It has been found that the chipping resistance of the cutting edge is improved by providing a rake face 31 having a negative rake angle, forming the rake face into multiple stages (31a, 31b), and recessing both end parts in the blade thickness direction of the rake face 31b rearward in the rotating direction. Furthermore, by providing a breaker 34 having a positive rake angle in the vicinity of the rake face 31, discharge of generated chips is promoted, and damage to the cut surface caused by the chips can be suppressed while ensuring the chipping resistance of the cutting edge.

The present application relates to machine tool processing tool technical field, especially in small size drilling and milling tool, to solve the problem of small tool micro machining and the problem of excessive wear of existing micro machining tool long distance milling, the scheme cutting part its axial front end face circumferential array at least two bottom edge, its outer circumferential circumferential array and bottom edge same number of side edge, bottom edge and side edge one to one correspondence;Each bottom edge one end extends to the outer circumferential of cutting part radially, and the lower end of its corresponding side edge is connected to form a tool tip, the other end extends to the tool rotation center radially and forms a center groove with the same length;The cutting rake angle gamma 1 of bottom edge is negative;The cutting rake angle gamma 2 of side edge is negative;Adjacent bottom edge is provided with chip groove, and adjacent side edge is provided with chip space and is communicated with chip groove;The present application guarantees the micro machining precision by setting negative rake angle, multiple bottom edge and multiple side edge and setting center groove, solves the problem of excessive wear of existing micro machining tool long distance milling.

The invention provides a difficult-to-machine material five-axis milling cutter attitude optimization method and system, and the method comprises the steps: building a three-dimensional thermal coupling finite element model comprising cutter attitude parameters, the cutter attitude parameters comprising a front inclination angle and a side inclination angle of a cutter shaft relative to the surface of a workpiece; based on the three-dimensional thermal coupling finite element model, thermal coupling simulation is conducted on the five-axis milling process under the set cutter posture parameters, and the cutting temperature and cutting force of a cutter-workpiece meshing area are obtained; extracting a cutting temperature peak value and a cutting force peak value from a result of thermal coupling simulation as key output variables; and by taking the front rake angle and the side rake angle as design variables and taking minimization of the key output variable as an optimization target, determining the optimal front rake angle and the optimal side rake angle of the tool by iteratively updating tool attitude parameters and repeating simulation and extraction. The intermittent cutting characteristic of five-axis milling, the complex space tool-workpiece contact relation and the force-heat coupling effect can be accurately simulated, and the simulation result is closer to the physical reality.

This cutting edge has a convex curved edge that is a curve convex toward the outer circumference of the tip of a cutting insert. A rake angle (α) in a normal direction of a rake face of the convex curved edge is a negative angle over an entire length of the convex curved edge, and gradually increases to the negative angle side as an end point on a rear end side of the convex curved edge is approached at a radiation angle (θ) of 15°-90°. Where a change amount of the rake angle (α) in the normal direction per 15° of an angle range of the radiation angle (θ) is σ1, σ1 ≤ 3.0°. Where a change amount of the rake angle in an axial direction per 15° of the angle range of the radiation angle (θ) is σ2, σ2 ≤ 6.0° when the radiation angle (θ) is 60°-90°.

A thread cutting tool (1) is provided with a tool body (2) that rotates about an axis and a cutting blade section (3). The cutting edge part (3) is provided with a plurality of thread cutting edges (6) protruding radially outward on the outer surface of the tool body (2). The plurality of thread cutting edges (6) are arranged side by side in the circumferential direction of the tool body (2), and the positions of the thread cutting edges (6) in the axial direction coincide with each other. When the tooth crest width of the thread cutting edge (6) is defined as W and the tooth crest height of the thread cutting edge (6) is defined as H, the relationship of 3% < = W / H < = 10% is satisfied, and when the rake angle of the thread cutting edge (6) is defined as theta, the relationship of-20 DEG < = theta < =-5 DEG is satisfied.

The invention discloses a medical orthopedic annular casing drill, and relates to the field of medical equipment, a drill bit is provided with an inclined cutting assembly, and chip removal assemblies are arranged between a drill body and the drill bit; the inclined cutting assembly comprises a tool face, a first auxiliary rear tool face, a second auxiliary rear tool face, a first main rear tool face, a front tool face and a second main rear tool face, wherein the first main rear tool face and the front tool face intersect to form a main cutting edge; the chip removal assembly comprises an inner cavity, an inner cavity face, an inclined opening and a vent hole, the inner cavity is formed in the drill bit, the inner cavity face is obliquely arranged in the inner cavity, and the inclined opening matched with the inner cavity face is formed in one end of the vent hole. The cutting edge inclination angle ensures the sharpness of the drill bit, the axial relief angle is formed by the reference plane included angle formed by the main cutting edge and the central axis of the drill body, the situation that a tool nose is broken due to large cutting resistance is effectively prevented, and fine bone chips generated during drilling are discharged through vacuum chip suction.

The invention discloses a curved surface milling surface roughness prediction method based on dynamic and static data fusion. The method comprises the following steps: firstly, acquiring a three-axis milling force sequence to form a milling force time sequence data matrix; acquiring a spindle rotating speed, a feeding speed, a cutting depth, a cutting width, a front rake angle, a roll angle and a curvature radius to form a milling static data matrix; then, constructing a surface roughness prediction model which comprises a dynamic data feature extraction module, a static data feature extraction module and a prediction head; the milling force time sequence data matrix passes through a dynamic data feature extraction module to obtain dynamic data features; the milling static data matrix passes through a static data feature extraction module to obtain static data features; the prediction head predicts the surface roughness by using the dynamic data features and the static data features; and finally, the surface roughness prediction model is trained, and the trained model is used for surface roughness prediction. According to the method, high-precision prediction of the surface roughness is realized by combining dynamic and static milling data.

The invention provides a sectional type multi-blade spiral milling cutter for milling a semiconductor material and a machining method, and relates to the field of spiral milling cutters. The machining method comprises the steps that according to cutter bar outer diameter parameters of a target sectional type multi-blade spiral milling cutter, the outer diameter of a cutter bar base material is milled, and a first cutter bar is obtained; milling one end of the first cutter bar to obtain a second cutter bar; according to the preset number of the tool bits, the second tool bar is subjected to groove milling treatment, and a third tool bar is obtained; according to the preset number of the tool bits and the initial parameters of the tool bits, the tool bit base material is subjected to segmented cutting treatment, and the tool bits in the target shape are obtained; a tool bit in the target shape is welded in the mounting groove, and a first sectional type multi-blade spiral milling cutter is obtained; and according to the first preset front angle, laser cutting treatment is conducted on the first sectional type multi-blade spiral milling cutter, and the target sectional type multi-blade spiral milling cutter is obtained. According to the scheme, the service life of the spiral milling cutter is prolonged, the machining efficiency is improved, and the machining quality of silicon carbide semiconductor materials is guaranteed.

The utility model discloses a kind of steel piece machining turning inserts, comprising: insert body, insert body is provided with several vertex angle;Several vertex angles are respectively provided with cutting edge, cutting edge is provided with circular arc angle blade and the inclined blade of both sides of circular arc angle blade;Cutting edge is sequentially provided with blade width, rake face, chip space, reverse chip surface along the middle part of insert body;Variable arc is arranged between blade width and rake face, rake face and inclined blade correspondingly are provided with front angle and are adapted with variable arc;Circular arc angle blade is flat angle blade.The turning insert can maximize tool tip stiffness, effectively improve the resonance frequency, and the insert forms a forced curling effect during semi-finishing, greatly shortening the length of chip breaking;And cutting heat is conducted away from the direction of tool tip, delaying the wear of tool tip crescent, avoiding surface quality decline and blade edge micro-collapse blade caused by flutter, ensuring the continuity of processing.

The application discloses a double-sided profiled high-efficiency milling cutter with large feeding and depth of cut, and particularly relates to the field of cutting tools, which comprises a cutter bar and a circular milling cutter, a plurality of groups of installation grooves are arranged in the circumferential direction at the bottom of the cutter bar, the installation grooves are inclined wedge sliding grooves with triangular cross sections, and a positioning gap is formed in the inner wall surface of the installation grooves. The circular milling cutter rotates synchronously, the exposed wavy cutting edge of the circular milling cutter is opposite to the surface of a workpiece, the area of the milling cutter embedded in the installation grooves only plays a positioning and cooperating role and does not participate in cutting. The wavy cutting edge continuously and periodically contacts the material of the workpiece in the rotating state, a continuously changing positive blade rake angle can be formed during cutting, the workpiece allowance is peeled off layer by layer, the cutting load can be uniformly dispersed, progressive cutting and stable chip breaking can be realized, cutting vibration and impact can be effectively reduced, and the stability and reliability of the cutting operation can be greatly improved. The wavy cutting edges are designed on both sides of the circular milling cutter, so that the service life of the circular milling cutter is prolonged.

The cutting tool has a body extending from a first end toward a second end. The body has a cutting edge, a rake face, and a discharge groove. In the rake face, the second rake angle of the second face region, located closer to the second end than the first face region connected to the cutting edge, is smaller than the first rake angle of the first face region. The third rake angle of the third face region, located rearward in the direction of rotation and adjacent to the outer periphery of the body relative to the discharge groove, is smaller than the second rake angle.

According to the ball-end milling cutter, in the direction of a preset axis far away from a head part, an end blade comprises a first cutting section, a second cutting section and a third cutting section which are sequentially connected, and when the ball-end milling cutter works, the first cutting section, the second cutting section and the third cutting section are sequentially connected; the linear speed of the first cutting section, the linear speed of the second cutting section and the linear speed of the third cutting section are gradually increased, and the numerical values of the first cutting front angle of the first cutting section, the second cutting front angle of the second cutting section and the third cutting front angle of the third cutting section are gradually increased. Therefore, the strength of the first cutting section, the strength of the second cutting section and the strength of the third cutting section are gradually increased, and on the premise that the third cutting section has higher linear speed relative to the first cutting section and the second cutting section, the third cutting section can also have higher strength relative to the first cutting section and the second cutting section. And therefore, the tipping difficulty of the third cutting section is reduced, the strength of the end edge is improved, and the service life of the ball-end milling cutter is prolonged.

A drill bit is formed with a chip flute (7) at a front end outer peripheral portion of a drill bit main body (1) that rotates in a drill bit rotation direction (T) about an axis (O), a cutting edge (5) is formed at an intersection ridge line portion of a wall surface of the chip flute (7) that faces the drill bit rotation direction (T) and a front end relief surface (6), the cutting edge (5) has a main cutting edge portion (5B) that extends from an inner peripheral side of the drill bit main body (1) toward an outer peripheral side, and a cutting edge shoulder portion (5C) that reaches the outer periphery of the drill bit main body (1) from an outer peripheral end (P) of the main cutting edge portion (5B), and is honed, an actual rake angle increases on the negative angle side at an outer peripheral end (Q) of the cutting edge shoulder portion (5C) relative to the outer peripheral end (P) of the main cutting edge portion (5B), and a size of the honing is reduced.