A stepped split-cut drill and milling cutter with finishing edge for deep hole machining

Abstract

This utility model discloses a stepped split-cutting drill-and-milling cutter with a finishing edge for deep hole machining, relating to the field of metal cutting tool technology. It solves the problems of poor chip removal, low tool life, and poor inner wall roughness in deep hole machining with a depth ≥ 5 times the diameter. The drill-and-milling cutter includes a cutter body, a center hole, and a 180° rotationally symmetrical cutting assembly. The cutting assembly includes a center cutting edge (for positioning), a stepped split-cutting unit (first / secondary split-cutting edges to refine chips), a finishing edge (for finishing the hole wall), and a rake face (for chip guidance). The design includes a clearance positioning surface (to prevent interference) and a clearance surface (to reduce contact). During use, the two tool bodies are installed 180° opposite each other, with the finishing edge overlapping and the center edge offset past the center, achieving alternating cutting and full-process finishing. This invention can refine iron chips to a length ≤5mm, reduce chip clogging rate to below 5%, increase tool life by 30%-50%, and optimize the inner wall roughness of the hole to Ra0.8-Ra1.6, eliminating the need for secondary machining. It is suitable for machining deep holes with diameters of φ5-φ50mm and 5-12 times the diameter.

Description

Technical Field

[0001] This utility model belongs to the technical field of metal cutting tools, and relates to a stepped split-cut drill and milling cutter with finishing edge for deep hole machining. It is especially suitable for deep hole machining scenarios with a depth ≥ 5 times the diameter (such as deep holes of hydraulic valves, deep holes of bearing seats, deep holes of engine cylinder blocks, etc.). It can simultaneously achieve efficient cutting, smooth chip removal and hole wall finishing, and meet the integrated machining needs of precision deep holes. Background Technology

[0002] In the field of machining, deep hole machining (hole depth ≥ 5 times the diameter) has always been a recognized challenge due to its semi-enclosed machining space, poor heat dissipation, and long chip removal path. Existing deep hole drilling and milling cutters face the following core problems in practical applications: Poor chip removal is a prominent problem: Traditional deep hole tools mostly use a single cutting edge structure, and the iron chips generated during the machining process are large and continuous (often 10-20mm in length). The narrow chip removal channel inside the deep hole cannot accommodate such iron chips, which easily cause accumulation and blockage. After blockage, it will not only scratch the machined hole wall, but also block the flow of coolant to the cutting area, causing the local temperature of the cutting edge to rise sharply to 600-800℃, which will aggravate wear. Tool life is generally short: Under high temperature environment, the cutting edge of the tool is prone to thermal wear and cracking. Especially when machining high-strength alloy materials such as 20CrMnTi and 40Cr, the existing tool life is usually only 1 / 2 to 1 / 3 of that for shallow hole machining. Taking the machining of 45# steel with a φ10mm hole diameter and a depth of 5 times the diameter as an example, traditional tools can only machine 150-200 holes before needing to be replaced. Frequent tool replacement leads to a decrease in machining efficiency of more than 30%. The surface roughness of the hole wall is difficult to meet the standard: Existing deep hole tools do not have a dedicated finishing structure. After machining, the inner wall of the hole often has cutting marks and burrs. The surface roughness is mostly Ra3.2-Ra6.3, which cannot meet the requirements of precision parts (such as deep holes in hydraulic systems that require Ra1.6 or less). Additional secondary machining processes such as honing and internal grinding are required, which not only increases the machining cost, but may also cause the hole axis to shift due to secondary clamping. Insufficient adaptability: Some manufacturers have tried to add chip breaker grooves or single finishing edges to the cutting tools, but chip breaker grooves can only segment the chips and cannot refine them to short chips suitable for deep hole chip removal; a single finishing edge will increase cutting resistance and further aggravate the thermal load on the cutting edge, failing to achieve the synergistic optimization of "chip breaking-chip removal-finishing", and cannot be adapted to the machining of ultra-deep holes with a diameter of 5 times or more. Therefore, in order to solve the above technical problems, the technical solution of this application is set up. Utility Model Content

[0003] The purpose of this utility model is to provide a stepped split-cut drill and milling cutter with finishing edge for deep hole machining. Through the design of "stepped split-cutting unit + special finishing edge + cooperative installation structure", it realizes the integration of chip refinement, cutting temperature reduction and hole wall finishing in deep hole machining, and meets the precision machining requirements of deep holes with a depth ≥ 5 times the diameter.

[0004] The technical solution adopted in this utility model is as follows: A stepped split-cut milling cutter with finishing edge for deep hole machining includes a cutter body and a center hole at the center of the cutter body. The center hole is used to cooperate with the cutter shank to realize the installation and positioning of the cutter body. The inner wall of the center hole is provided with a keyway with a width of 2-5mm, which can be fixed to the cutter shank by a flat key to prevent the cutter body from rotating circumferentially relative to the cutter shank due to axial and radial forces during deep hole machining.

[0005] The tool body has two sets of cutting components along its circumference. These two sets of cutting components are 180° rotationally symmetrical about the central hole, ensuring balanced force during tool rotation and preventing runout during deep hole machining. Each cutting component includes a central cutting edge, a stepped splitting unit, a finishing edge, a rake face, a clearance positioning surface, and a clearance surface. These components work together to achieve positioning, splitting, finishing, and chip removal functions. The center cutting edge is set at a preset position along the radial direction of the tool body. It is a horizontal cutting edge with a cutting edge length of 1 / 5 to 1 / 4 of the machining hole diameter (e.g., a cutting edge length of 2-2.5 mm corresponds to a φ10 mm hole diameter). In the initial stage of machining, it first contacts the workpiece and ensures that the tool axis coincides with the hole axis through the two-point positioning principle, thus avoiding hole wall skewing caused by positioning deviation during deep hole machining. The stepped chipping unit consists of a primary chipping edge and a secondary chipping edge, which is the core structure for refining chips. One end of the primary chipping edge is connected to the central cutting edge, with an included angle α of 10°-20° (preferably 15°, balancing cutting efficiency and chipping effect). The other end is connected to the secondary chipping edge in a stepped parallel shape, with a step height (projected height along the tool body axis) of 0.1-0.3mm. During machining, the primary chipping edge first cuts 1 / 3-1 / 2 of the surface layer of the workpiece, and the secondary chipping edge then cuts the remaining cutting amount, refining the long chips generated by the traditional single cutting edge into short chips with a length of ≤5mm, which is suitable for narrow chip removal channels in deep holes. The finishing edge is set perpendicular to the center edge, with one end connected to the end of the secondary cutting edge furthest from the primary cutting edge. The cutting edge length is 1 / 3 to 1 / 2 of the depth of the machined hole (e.g., a cutting edge length of 18-25mm corresponds to a 50mm deep hole), and the cutting edge roughness is ≤Ra0.4 (achieved through fine grinding). During the cutting process, the finishing edge remains in contact with the hole wall, which can remove the cutting marks left by the primary / secondary cutting edges and at the same time trim the burrs on the hole wall, achieving one-time finishing and shaping of the inner wall of the deep hole. The rake face adopts a negative rake angle design (rake angle is -5° to -2°), which is connected to the cutting edge side of the center cutting edge, the first-stage cutting edge, the second-stage cutting edge and the finishing edge to form a chip discharge channel; the surface of the rake face is provided with chip breakers (height 0.08-0.15mm) spaced 2-5mm apart. When the refined chips move along the rake face, the chip breakers can further break them into shorter chips, and at the same time guide the chips to be discharged along the inclined direction of the rake face to avoid accumulation in the deep hole; The clearance positioning surface is located on the side of the finishing blade away from the rake face, and its height is 0.05-0.2mm lower than the cutting edge of the finishing blade (if the cutting edge height of the finishing blade is 1mm, the clearance positioning surface height is 0.8-0.95mm), and its surface roughness is ≤Ra1.6. Its functions are: first, to avoid excessive contact between the non-cutting edge part of the tool body and the hole wall during the finishing process, thereby reducing frictional resistance; second, to help the finishing blade maintain a stable finishing posture and prevent the finishing accuracy from decreasing due to tool vibration. The clearance surface connects the finishing blade and the clearance positioning surface, and adopts an arc transition design (arc radius 0.5-1mm), which can reduce the interference between the tool body and the unmachined part of the workpiece in deep hole machining. It is especially suitable for ultra-deep hole machining scenarios with hole depth ≥ 8 times the diameter, avoiding hole wall scratches caused by insufficient clearance.

[0006] To achieve full coverage of deep hole machining and finishing, two tool bodies must be installed on the same tool holder through the center hole, arranged in opposite directions at 180°. The center cutting edge of one tool body (tool body A) is 0.1-0.2mm away from the axis of the center hole, while the center cutting edge of the other tool body (tool body B) coincides with the axis of the center hole (i.e., passes through the center), forming a "misaligned positioning" structure to ensure cutting coverage of the central area of ​​the deep hole. At the same time, the finishing edges of the two tool bodies overlap horizontally with an overlap length of 0.5-1mm to avoid finishing blind spots and ensure full finishing of the inner wall of the deep hole from the opening to the bottom.

[0007] The working principle of this utility model is as follows: through a five-stage coordinated mechanism of "positioning-splitting-chip breaking-finishing-chip removal", precision machining of deep holes with a depth ≥ 5 times the diameter is achieved. The specific working process is as follows: Dual positioning stage: After the tool starts, the two tool bodies (tool body A and tool body B) mounted on the tool holder rotate synchronously. The center cutting edge (beyond the center) of tool body B contacts the center area of ​​the workpiece first, and the center cutting edge of tool body A contacts the edge area of ​​the workpiece. Through the dual positioning of "center + edge", the tool axis is ensured to coincide with the hole axis, avoiding hole wall skew caused by positioning deviation during deep hole machining (the skew amount can be controlled within ≤0.02mm / 50mm). Stepped cutting stage: When the tool feeds along the axial direction, the first-stage cutting edges of tool body A and tool body B alternately cut the surface material of the workpiece (the cutting amount accounts for 1 / 3-1 / 2 of the total cutting amount), and then the second-stage cutting edges alternately cut the remaining material. Because the first-stage / second-stage cutting edges are distributed in a stepped manner, the iron chips generated during the cutting process are naturally divided into two segments, and finally short chips with a length of ≤5mm are formed, avoiding the entanglement of traditional long chips in deep holes. Assisted chip breaking and removal stage: The refined iron chips move along the rake face under the action of centrifugal force. When they come into contact with the chip breaking table of the rake face, they are further broken into chips with a length of 2-3mm. At the same time, external coolant is sprayed into the deep hole through the internal cooling channel of the tool holder. Under the flushing action of the coolant, the chips are discharged from the deep hole along the gap between the rake face and the hole wall. During the chip removal process, the coolant flows through the cutting area simultaneously, reducing the cutting edge temperature from 800℃ to 560-640℃, thus avoiding thermal wear of the cutting edge. Full-process finishing stage: While splitting and removing chips, the finishing edges of the two tool bodies are horizontally overlapped and in contact with the hole wall (overlap length 0.5-1mm). The finishing edge of tool body A performs the first finishing on the hole wall after splitting by tool body B to remove splitting marks; the finishing edge of tool body B performs the second finishing on the hole wall after splitting by tool body A to remove burrs from the hole wall; the clearance positioning surface is 0.05-0.2mm lower than the cutting edge of the finishing edge to avoid friction between the non-cutting edge parts of the tool body and the hole wall, ensuring stable finishing accuracy; Stable machining stage: The avoidance surface adopts a rounded transition design to reduce interference between the tool body and the unmachined part of the workpiece. Especially in the machining of ultra-deep holes with a depth ≥ 8 times the diameter, it can avoid vibration caused by the collision between the tool body and the hole wall. The precise fit between the center hole and the tool holder (clearance 0.005-0.01mm) and the circumferential fixing effect of the keyway ensure that the tool rotates stably at a speed of 1000-2000r / min without slippage or wobble, ultimately achieving efficient and precise machining of deep holes.

[0008] Furthermore: the horizontal cutting edge forms a surface contact with the workpiece surface, and with a cutting edge length of "not less than 1 / 5 of the hole diameter", a stable radial support structure is constructed. In the initial stage of deep hole machining, the tool runout is ≤0.02mm / 50mm, ensuring that the hole axis coincides with the tool axis. By limiting the size associated with the hole diameter, positioning failure caused by changes in the hole diameter is avoided. It can be adapted to machining multiple hole diameters from φ5 to φ50mm, enhancing the tool's versatility.

[0009] Furthermore: an included angle of 10°-20° allows the first-stage cutting edge to bear 1 / 3-1 / 2 of the total cutting amount (surface material), while the second-stage cutting edge bears the remaining cutting amount (inner material). The length ratio of 1.2-1.5 times optimizes the distribution of the cutting area, ensuring that the chips are uniformly refined into short chips with a length of ≤5mm. The reasonable included angle and length ratio disperse the cutting force, reducing the maximum cutting force of the first-stage cutting edge by 20%-30%, avoiding chipping of the cutting edge due to local overload, and is especially suitable for machining high-strength materials such as 20CrMnTi.

[0010] Furthermore: the parallel setting ensures that the cutting paths of the splitting blades are parallel, and the chips are discharged in a single direction to avoid entanglement; the step height of 0.1-0.3mm ensures complete chip separation, while reducing the machining steps of the secondary splitting blades, reducing the finishing allowance from 0.05mm to below 0.02mm, and improving finishing efficiency by 40%; the parallel splitting blades combined with the reasonable step height optimize the pre-machining roughness of the hole wall after splitting from Ra6.3 to Ra3.2, laying the foundation for subsequent finishing.

[0011] Furthermore: the vertical setting ensures that the finishing blade fully fits the hole wall without any blind spots; the length is not less than 1 / 3 of the hole depth, and the two blades overlap at 180° in opposite directions (overlap length 0.5-1mm), enabling full finishing from the hole opening to the bottom (e.g., a 50mm long finishing blade can cover the entire length of a 150mm deep hole); the cutting edge roughness of Ra0.4 ensures that the roughness of the hole wall is stable at Ra0.8-Ra1.6 after finishing, eliminating the need for secondary honing and improving processing efficiency by 25%.

[0012] Furthermore: a height difference of 0.05-0.2mm ensures that the clearance positioning surface does not contact the hole wall (preventing scratches), while assisting the finishing blade to maintain a stable posture, reducing the vibration amplitude of the finishing blade from 0.03mm to below 0.01mm; a surface roughness of Ra1.6 prevents residual debris from the clearance positioning surface, reducing the hole wall scratch rate from 15% in the prior art to below 3%.

[0013] Furthermore: the 2-5mm interval ensures that the chips are broken further after traveling a certain distance (reducing the chip length from 5mm to 2-3mm), and the height of 0.08-0.15mm ensures the chip breaking effect; combined with the negative rake angle of the rake face, the chip removal speed is increased by 30%-40%, and the chip clogging rate is reduced from 5% to below 1%; the raised structure formed by the chip breaking table guides the coolant flow to the cutting area, increasing the coolant reach rate from 80% to 95%, and further reducing the cutting edge temperature by 5%-10%.

[0014] Furthermore: the marking points quickly distinguish the installation direction of the tool body, reducing the installation time from 10 minutes to 2 minutes and avoiding rework due to incorrect orientation; through the positioning of the marking points, the overlap length error of the finishing edge is reduced from ±0.2mm to ±0.05mm (without finishing blind spots), the accuracy of the center edge misalignment distance is improved, and the cutting coverage of the center area is increased from 90% to 100%.

[0015] Furthermore: Carbide (HRA92.5) or high-speed steel (HRC64) ensures the rigidity of the tool body, which can withstand high-speed rotation of 1000-2000r / min; TiAlN (HV3200) or AlCrN (HV3400, high temperature resistance 1100℃) coating improves the wear resistance of the cutting edge by 50%-80%, and extends the tool life from 200 holes to 350-400 holes when machining 45# steel; Carbide + TiAlN coating is suitable for machining steel and cast iron, and high-speed steel + AlCrN coating is suitable for machining aluminum alloy and stainless steel, thus broadening the application range of the tool.

[0016] Furthermore: a thickness of 3-8mm adapts to different specifications of tool holders, ensuring tool body rigidity (vibration amplitude ≤0.01mm); a fit clearance of 0.005-0.01mm ensures a tight fit between the tool body and the tool holder, optimizing hole perpendicularity from 0.03mm / 50mm to 0.02mm / 50mm; the keyway fit with the flat key can transmit sufficient torque (e.g., a 3mm keyway can transmit 150N・m torque), preventing tool body rotation, improving cutting trajectory accuracy, and stabilizing hole diameter tolerance at H7 level (e.g., φ10mm±0.015mm).

[0017] In summary, due to the adoption of the above technical solution, the beneficial effects of this utility model are: 1. A stepped chipping type milling cutter with finishing edge for deep hole machining, which refines iron chips into short chips with a length of ≤5mm through a stepped chipping unit, and with the design of a rake face chip-breaking table and negative rake angle, iron chips can be quickly discharged along the rake face; according to actual tests, when machining 45# steel in φ10mm and 50mm deep holes, the chip removal blockage rate is reduced from 35% of the existing technology to below 5%, and the coolant can directly reach the cutting area through the chip removal channel, solving the heat dissipation problem of deep hole machining.

[0018] 2. In this utility model, the stepped splitting unit disperses the axial cutting force into two segments, reducing the cutting temperature of the cutting edge by 20%-30% (from 800℃ to 560-640℃). Combined with the TiAlN / AlCrN wear-resistant coating on the cutting edge, the tool life is increased by 30%-50%. Taking the machining of 45# steel with a φ10mm hole diameter as an example, the existing tool life is 200 holes, while this utility model can reach 350-400 holes, reducing the number of tool changes and increasing the machining efficiency by more than 25%.

[0019] 3. In this utility model, the finishing blade and the anti-cavity positioning surface work together to optimize the roughness of the inner wall of the deep hole from Ra3.2-Ra6.3 in the prior art to Ra0.8-Ra1.6, and the hole diameter tolerance can be stably controlled at the H7 level (such as φ10mm hole diameter tolerance +0.015 / -0). No additional honing or boring is required, and the processing cost per hole is reduced by 15%-20%.

[0020] 4. In this utility model, by adjusting the included angle of the stepped cutting unit, the length of the finishing blade and the thickness of the tool body, it can be adapted to deep hole machining with a diameter of φ5-φ50mm and a diameter of 5-12 times. It is suitable for a variety of materials such as 45# steel, 20CrMnTi, cast iron, and aluminum alloy, and can meet the deep hole machining needs of industries such as machinery manufacturing, automotive parts, and hydraulic equipment. Attached Figure Description

[0021] To more clearly illustrate the technical solutions of the embodiments of this utility model, the drawings used in the embodiments will be briefly described below. It should be understood that the following drawings only show some embodiments of this utility model and should not be regarded as a limitation on the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort, wherein: Figure 1 This is a schematic diagram of the structure of this utility model; Figure 2 This is a schematic diagram of the assembly of the two blades when the present invention is in use; Figure 3 This is a top view of a single-piece tool body; Figure 4 yes Figure 3 Sectional view of AA; Figure 5 This is a left view of a single-piece cutter body; Figure 6 This is a bottom view of a single-piece cutter body; Figure 7 This is the front view of a single cutter body; The markings in the diagram are: 1-tool body, 2-center hole, 3-center cutting edge, 4-finishing cutting edge, 5-front face, 6-avoidance positioning surface, 7-avoidance surface, 8-first-level cutting edge, 9-second-level cutting edge, 10-cutting platform, 11-marking point, 12-keyway.

[0022] Explanation of the reference numerals in the above figures: First-level cutting edge (component of stepped cutting unit), second-level cutting edge (component of stepped cutting unit), cutting table (auxiliary structure of rake face), marking point (for installation and positioning), keyway (inner wall of center hole, for circumferential fixing). Detailed Implementation

[0023] To make the objectives, technical solutions, and advantages of this utility model clearer, the present utility model will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only for explaining the present utility model and are not intended to limit the present utility model; that is, the described embodiments are only some embodiments of the present utility model, and not all embodiments. The components of the embodiments of the present utility model described and shown in the accompanying drawings can generally be arranged and designed in various different configurations.

[0024] Therefore, the following detailed description of the embodiments of the present invention provided in the accompanying drawings is not intended to limit the scope of the claimed invention, but merely to illustrate selected embodiments of the invention. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without inventive effort are within the scope of protection of the present invention.

[0025] It should be noted that relational terms such as "first" and "second" are used merely to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitations, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element.

[0026] The features and performance of this utility model will be further described in detail below with reference to the embodiments.

[0027] Example 1:

[0028] This utility model discloses a stepped split-cut drill and milling cutter with finishing edge for deep hole machining, such as... Figure 1 As shown, it includes a cutter body 1 and a central hole 2 opened in the center of the cutter body 1. The cutter body 1 is provided with at least one set of cutting components along the circumference. Each set of cutting components includes a central cutting edge 3, a stepped cutting unit, a finishing edge 4, a rake face 5, a clearance positioning surface 6, and a clearance surface 7. The center cutting edge 3 is set at a preset circumferential position on the tool body 1 to achieve center positioning during machining; The stepped cutting unit includes a primary cutting edge 8 and a secondary cutting edge 9. One end of the primary cutting edge 8 is connected to the central cutting edge 3, and the other end is connected to the secondary cutting edge 9 in a stepped manner to refine the iron filings generated during the machining process. The finishing blade 4 is set at a preset angle to the center blade 3 and is connected to the end of the secondary cutting blade 9 that is away from the primary cutting blade 8, and is used to finish the inner wall of the machined hole. The front face 5 is connected to the cutting edge side of the center cutting edge 3, the first-stage cutting edge 8, the second-stage cutting edge 9 and the finishing edge 4 to guide the iron chips out. The clearance positioning surface 6 is connected to the side of the finishing blade 4 away from the front face 5, and the height of the clearance positioning surface 6 is lower than the cutting edge height of the finishing blade 4, in order to avoid interference with the hole wall during the finishing process. The clearance surface 7 is connected to the finishing blade 4 and the clearance positioning surface 6 respectively, in order to reduce unnecessary contact between the tool body 1 and the workpiece being processed; The cutting assembly is arranged symmetrically about the center hole 2 at 180°. When in use, at least two tool bodies 1 are installed on the tool holder through the center hole 2, distributed in opposite directions at 180°. The finishing edges 4 of adjacent tool bodies 1 are horizontally overlapped, and the center edge 3 of one tool body 1 is closer to the axis of the center hole 2 than the center edge 3 of the other tool body 1, which is suitable for deep hole machining scenarios with a depth ≥ 5 times the diameter.

[0029] The center cutting edge 3 is a horizontal cutting edge that extends radially along the tool body 1, and the cutting edge length of the center cutting edge 3 is not less than 1 / 5 of the machining hole diameter, ensuring the positioning stability in the initial stage of deep hole machining.

[0030] The included angle α between the first-stage cutting edge 8 and the center cutting edge 3 satisfies 10°≤α≤20°, and the length of the first-stage cutting edge 8 is 1.2-1.5 times the length of the second-stage cutting edge 9. The chip refinement is achieved through the gradient distribution of cutting amount.

[0031] The first-stage cutting edge 8 and the second-stage cutting edge 9 are parallel to each other, and the step height between them is 0.1-0.3mm to prevent iron filings from getting tangled around the cutting edge during the cutting process.

[0032] The finishing blade 4 is set perpendicular to the center blade 3, and the cutting edge length of the finishing blade 4 is not less than 1 / 3 of the depth of the machined hole, and the cutting edge roughness is ≤Ra0.4, ensuring that the inner wall of the deep hole is fully finished and covered.

[0033] The height difference between the clearance positioning surface 6 and the cutting edge of the finishing blade 4 is 0.05-0.2mm, and the surface roughness is ≤Ra1.6, which reduces hole wall friction while ensuring finishing accuracy.

[0034] A chip-breaking platform 10 is provided on the rake face 5. The chip-breaking platform 10 is set at intervals of 2-5mm along the length direction of the rake face 5 and has a height of 0.08-0.15mm to help the refined iron chips be quickly discharged from the deep hole.

[0035] A marking point 11 is provided on the upper surface of the blade body 1 near the center hole 2 to mark the installation direction of the blade body 1 and ensure the overlap accuracy of the finishing blade 4 when the two blade bodies 11 are installed in opposite directions at 180°.

[0036] The tool body 1 is made of cemented carbide or high-speed steel. The cutting edges of the center cutting edge 3, the first-stage cutting edge 8, the second-stage cutting edge 9, and the finishing edge 4 are coated with TiAlN or AlCrN wear-resistant coatings with a thickness of 3-8μm to improve the wear resistance of the cutting edges in deep hole machining.

[0037] The thickness of the tool body 1 is 3-8mm, the clearance between the central hole 2 and the tool holder is 0.005-0.01mm, and the inner wall of the central hole 2 is provided with a keyway 12 to achieve circumferential fixation of the tool body 1 and the tool holder, so as to avoid the tool body 1 slipping during deep hole machining.

[0038] The specific implementation method of this embodiment is as follows: conventional deep hole machining with a diameter of 5 times (machining object: 45# steel, hole diameter φ10mm, hole depth 50mm, surface roughness required to be below Ra1.6). Tool body parameter design: Blade material: cemented carbide (WC-Co, Co content 8%, hardness HRA92.5), cutting edge coating: TiAlN (thickness 5μm, hardness HV3200). Center cutting edge: horizontal cutting edge, 2mm in length (1 / 5 of the hole diameter), cutting edge angle 60°; Stepped cutting unit: First-stage cutting edge length 6mm, second-stage cutting edge length 5mm, included angle α=15°, step height 0.2mm (axial projection). Finishing edge: 18mm in length (1 / 3 of the hole depth), edge roughness Ra0.2, perpendicular to the center edge, edge width 0.8mm; Clearance positioning surface: height is 0.1mm lower than the finishing blade, surface roughness Ra1.2, width 1.2mm; Rake face: rake angle -3°, break-off stage spacing 3mm, height 0.12mm, surface roughness Ra0.8; Tool body structure: 5mm thickness, φ8mm diameter center hole, 0.008mm clearance, 3mm keyway width, and a 1mm diameter circular indentation located on the upper surface of the tool body near the center hole.

[0039] Installation and processing parameter settings: Tool body installation: Two tool bodies are installed on the φ8mm tool shank through the center hole, and are distributed in opposite directions at 180°. The center cutting edge of tool body B passes through the center, and the center cutting edge of tool body A is 0.15mm away from the axis. The overlap length of the finishing edge is 0.8mm. Processing equipment: CNC milling machine (model XK714), equipped with a high-pressure cooling system (pressure 3MPa); Machining parameters: rotation speed 1800 r / min, feed rate 0.1 mm / r, depth of cut 50 mm, coolant: emulsion (concentration 8%, flow rate 20 L / min).

[0040] Processing effect verification: Chip removal performance: The chip length is 3-4mm, and the chips are short spirals with no accumulation in the holes. The chip removal efficiency is 98%, and the coolant can directly reach the cutting area. The actual measured cutting edge temperature is 600℃. Tool life: After continuously machining 380 holes, the edge wear is 0.08mm (not exceeding the wear limit of 0.1mm), which still meets the surface roughness requirements; Machining accuracy: inner wall roughness Ra1.0 (tested by a roughness tester), hole diameter tolerance φ10mm (+0.012 / -0) (H7 level), hole perpendicularity 0.02mm / 50mm (tested by a dial indicator), no scratches or burrs on the hole wall.

[0041] Example 2:

[0042] This utility model discloses a stepped split-cut drill and milling cutter with finishing edge for deep hole machining, such as... Figure 1 As shown, the specific implementation method of this embodiment is as follows: Machining of ultra-deep holes with a diameter of 10 times (machining object: 20CrMnTi, hole diameter φ15mm, hole depth 150mm, surface roughness required to be below Ra1.6, used for automotive gearbox shaft holes) Tool body parameter design: Blade material: high-speed steel (W6Mo5Cr4V2, hardness HRC64), cutting edge coating: AlCrN (thickness 7μm, hardness HV3400, high temperature resistance 1100℃). Center cutting edge: horizontal cutting edge, length 3mm (1 / 5 of the hole diameter), cutting edge angle 55°, cutting edge rounded 0.05mm; Stepped cutting unit: First-stage cutting edge length 8mm, second-stage cutting edge length 6mm, included angle α=12° (suitable for cutting high-strength materials), step height 0.15mm (axial projection). Finishing edge: 50mm in length (1 / 3 of the hole depth), edge roughness Ra0.3, perpendicular to the center edge, edge width 1.0mm, edge rounding 0.03mm; Clearance positioning surface: height is 0.08mm lower than the finishing blade, surface roughness Ra1.0, width 1.5mm; Rake face: rake angle -5° (enhancing cutting edge strength), chip breakage stage spacing 4mm, height 0.15mm, surface roughness Ra0.8, rake face inclination angle 10° (facilitating chip removal). Tool body structure: 7mm thickness, φ12mm diameter center hole, 0.006mm clearance, 4mm keyway width, and the marking point is a long strip-shaped protrusion (3mm long and 1mm wide) on the upper surface of the tool body.

[0043] Installation and processing parameter settings: Tool body installation: Two tool bodies are installed on a φ12mm special deep hole tool holder, distributed in opposite directions at 180°. The center cutting edge of tool body B passes through the center, and the center cutting edge of tool body A is 0.2mm away from the axis. The finishing edge overlap length is 1.0mm. The tool holder is equipped with an internal cooling channel (3mm in diameter). Processing equipment: Deep hole drilling machine (model ZK2103), equipped with a high-pressure internal cooling system (pressure 5MPa); Machining parameters: rotation speed 1200 r / min, feed rate 0.08 mm / r, depth of cut 150 mm (3 feeds, 50 mm each), coolant: oil-based cutting fluid (viscosity 20 cSt / 40℃, containing extreme pressure additives, flow rate 30 L / min).

[0044] Processing effect verification: Chip removal performance: The iron chips are 2-3mm in length and are in the form of fragments. They are forced out by the high-pressure internal coolant without accumulation in the holes. The actual measured cutting edge temperature is 580℃ (20CrMnTi is prone to heat generation during machining, and this temperature can effectively prevent thermal wear). Tool life: After machining 220 holes continuously, the edge wear is 0.10mm, which still meets the surface roughness requirements (the surface roughness increases to Ra1.8 when machining 230 holes, reaching the wear limit). Machining accuracy: inner wall roughness Ra1.2 (measured by roughness tester), hole diameter tolerance φ15mm (+0.015 / -0) (H7 level), hole perpendicularity 0.03mm / 150mm (measured by deep hole tester), no scratches or built-up edge on the hole wall, meeting the assembly requirements of automotive gearbox shaft holes.

[0045] The above description is only a preferred embodiment of the present utility model and is not intended to limit the scope of protection of the present utility model. Any modifications, equivalent substitutions and improvements made by those skilled in the art within the spirit and principles of the present utility model should be included within the scope of protection of the present utility model.

Claims

1. A stepped fractional cutting type band finishing edge drill milling cutter for deep hole machining, characterized by: The utility model relates to a cutting tool, including cutter body (1) and the central hole (2) of setting in the center of cutter body (1), cutter body (1) is equipped with at least one group of cutting assembly along the circumference, and each group cutting assembly includes center blade (3), stepped cutting unit, finishing blade (4), rake face (5), clearance positioning surface (6), avoidance surface (7); Center blade (3) is arranged at the preset circumferential position of cutter body (1), is used for realizing center positioning when machining; Stepped cutting unit includes primary cutting edge (8) and secondary cutting edge (9), one end of primary cutting edge (8) is connected with center blade (3), the other end is connected with secondary cutting edge (9) and is connected in stepped form, is used for refining iron filings produced in the machining process; Finishing blade (4) is arranged at the preset angle with center blade (3), and is connected with the one end of secondary cutting edge (9) away from primary cutting edge (8), is used for finishing the inner wall of the machining hole; Rake face (5) is connected with the cutting edge side of center blade (3), primary cutting edge (8), secondary cutting edge (9) and finishing blade (4), is used for guiding iron filings to discharge; Clearance positioning surface (6) is connected with the side of finishing blade (4) away from rake face (5), and the height of clearance positioning surface (6) is lower than the height of the cutting edge of finishing blade (4), is used for avoiding interference with the hole wall during finishing; Avoidance surface (7) is connected with finishing blade (4) and clearance positioning surface (6) respectively, is used for reducing unnecessary contact between cutter body (1) and machining workpiece; The cutting assembly is arranged in 180 degree rotation symmetry about the central hole (2), and at least two cutter bodies (1) are installed on the cutter bar through the central hole (2) during use, are distributed in 180 degree reverse direction, the finishing blades (4) of adjacent cutter bodies (1) are horizontally overlapped, and the center blade (3) of one piece of cutter body (1) is closer to the axis of the central hole (2) than the center blade (3) of the other piece of cutter body (1), and the depth of adaptation is greater than or equal to 5 times the diameter of the deep hole machining scene.

2. The stepped fractional cutting type band dressing edge drill milling cutter for deep hole machining according to claim 1, characterized in that: The center blade (3) is a horizontal cutting edge extending along the radial direction of the cutter body (1), and the length of the cutting edge of the center blade (3) is not less than 1 / 5 of the diameter of the machining hole, ensuring the positioning stability in the initial stage of deep hole machining.

3. The stepped fractional cutting type band resharpening drill milling cutter for deep hole machining according to claim 1, characterized in that: The included angle α between the primary cutting edge (8) and the center blade (3) satisfies 10°≤α≤20°, and the length of the primary cutting edge (8) is 1.2-1.5 times the length of the secondary cutting edge (9), so that the iron filings are refined through the gradient distribution of cutting amount.

4. The stepped fractional cutting type band resharpening drill milling cutter for deep hole machining according to claim 1, characterized in that: The primary cutting edge (8) and the secondary cutting edge (9) are parallel to each other, and the stepped height between them is 0.1-0.3mm, avoiding the winding of iron filings around the cutting edge during cutting.

5. The stepped fractional cutting type band resharpening drill milling cutter for deep hole machining according to claim 1, characterized in that: The finishing blade (4) is perpendicular to the center blade (3), and the length of the cutting edge of the finishing blade (4) is not less than 1 / 3 of the depth of the machining hole, and the roughness of the cutting edge is less than or equal to Ra0.4, ensuring the finishing of the inner wall of the deep hole.

6. The stepped fractional cutting type band resharpening drill milling cutter for deep hole machining according to claim 1, characterized in that: The height difference between the clearance positioning surface (6) and the cutting edge of the finishing blade (4) is 0.05-0.2mm, and the surface roughness is less than or equal to Ra1.6, which reduces the friction of the hole wall while ensuring the finishing accuracy.

7. The stepped fractional cutting type band resharpening drill milling cutter for deep hole machining according to claim 1, characterized in that: The rake face (5) is provided with a broken cutting platform (10), the broken cutting platform (10) is arranged along the length direction of the rake face (5) with an interval of 2-5mm, and the height is 0.08-0.15mm, which can help the refined iron filings to be discharged from the deep hole quickly.

8. The stepped fractional cutting type band resharpening drill milling cutter for deep hole machining according to claim 1, characterized in that: The upper surface of the cutter body (1) is provided with a mark point (11) near the center hole (2), which is used for identifying the installation direction of the cutter body (1) and ensuring the lap joint accuracy of the light trimming edge (4) when the two cutter bodies (1) are installed in the opposite direction by 180°.

9. The stepped fractional cutting type band resharpening drill milling cutter for deep hole machining according to claim 1, characterized in that: The cutter body (1) is made of hard alloy or high-speed steel, and the edge of the center edge (3), the first-stage sub-cutting edge (8), the second-stage sub-cutting edge (9) and the light trimming edge (4) is provided with a TiAlN or AlCrN wear-resistant coating, and the thickness of the coating is 3-8μm, which can improve the wear resistance of the edge in deep hole machining.

10. The stepped fractional cutting type band resharpening drill milling cutter for deep hole machining according to claim 1, characterized in that: The thickness of the cutter body (1) is 3-8mm, the cooperation gap between the center hole (2) and the cutter rod is 0.005-0.01mm, the inner wall of the center hole (2) is provided with a key groove (12), the circumferential fixation of the cutter body (1) and the cutter rod is realized, and the cutter body (1) is prevented from slipping during deep hole machining.

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