Cutter and preparation method

Abstract

The invention discloses a cutter and a preparation method, and relates to the technical field of cutter coatings. The drill point is prepared by depositing the wear-resistant coating on the surface of the cutter base body of the drill point and then grooving to prepare the cutting edge, so that the wear-resistant coating with higher thickness can be deposited on the premise that the cutting performance is not influenced; internal stress between materials with different hardness is buffered through the stacking design of the transition layer and the functional layer in the wear-resistant layer, so that the service life of the drill point is greatly prolonged, meanwhile, the stability of the drill point is better, and the drilling quality is higher.

Description

Technical Field

[0001] This invention relates to the field of cutting tool coating technology, and in particular to a cutting tool and its preparation method. Background Technology

[0002] Cutting tools such as micro drills or drill bits are widely used in PCB drilling. With the improvement of processing efficiency and the change of processed materials, higher requirements are placed on the wear resistance of drill bit coatings. For example, conventional drill bits cannot meet the needs of thicker or more complex PCBs. Related technologies improve the service life and wear resistance of drill bits by increasing the thickness of the wear-resistant coating. However, the internal stress of the wear-resistant coating increases with the increase of the coating thickness. When the coating thickness reaches about 2.0 μm, it will damage the cutting edge of the drill bit and significantly weaken its cutting performance. There is an urgent need for a drill bit manufacturing method that can significantly extend the service life of drill bits while retaining their cutting performance. Summary of the Invention

[0003] The main objective of this invention is to develop a drill bit with a thicker wear-resistant coating, which can significantly extend the service life of the drill bit without affecting its cutting performance.

[0004] To achieve the above objectives, the present invention proposes a method for preparing a cutting tool, the method comprising the following steps: S1. A wear-resistant coating is deposited on the surface of the tool substrate to obtain the tool intermediate; S2. Grooving is performed on the surface of the intermediate tool body obtained in step S1 to form a cutting edge and a chip removal groove, thus completing the preparation of the tool.

[0005] In one embodiment, the tool body includes a drill bit head, a UC portion, and a base connected in sequence; wherein the length of the drill bit head is 0.5mm to 1.5mm; and / or, the diameter of the drill bit head is 0.15mm to 0.5mm.

[0006] In one embodiment, the coaxiality of the drill bit head and the spindle of the tool base does not exceed 8 μm; and / or, the coaxiality of the UC part and the spindle of the tool base does not exceed 8 μm.

[0007] In one embodiment, the roundness of the drill bit head is not less than 2 μm.

[0008] In one embodiment, in step S1, a wear-resistant coating is deposited on the drill bit tip of the tool substrate to obtain a wear-resistant coating with a thickness of 4μm to 8μm.

[0009] In one embodiment, the wear-resistant coating comprises metallic and non-metallic elements; wherein the metallic elements include at least one of Cr, Al, Ti, V, Y, Nb, and Mo; and / or the non-metallic elements include at least one of Si, N, O, and C.

[0010] The present invention also proposes a cutting tool, which is prepared by the cutting tool preparation method described above. The cutting tool includes a cutting tool substrate and a wear-resistant coating disposed on the outer surface of the cutting tool substrate, and the thickness of the wear-resistant coating is 4μm~8μm.

[0011] In one embodiment, a transition layer is further provided between the tool substrate and the wear-resistant coating, the thickness of the transition layer being 0.3μm~0.5μm.

[0012] In one embodiment, the transition layer includes a first sub-transition layer, a second sub-transition layer, and a third sub-transition layer, each with a thickness of 0.1 μm to 0.2 μm, stacked sequentially from the tool substrate outwards; wherein the hardness of the first sub-transition layer is 8 GPa to 12 GPa; and / or, the hardness of the second sub-transition layer is 13 GPa to 17 GPa; and / or, the hardness of the third sub-transition layer is 18 GPa to 22 GPa.

[0013] In one embodiment, the wear-resistant coating includes a first functional layer and a second functional layer with a thickness of 2μm to 4μm, which are sequentially stacked from the transition layer outward; wherein the hardness of the first functional layer is 25GPa to 34GPa; and / or the hardness of the second functional layer is 35GPa to 45GPa.

[0014] The technical solution of this invention designs a method for preparing a drill bit. The drill bit is obtained by first depositing a wear-resistant coating on the surface of the tool substrate and then grooving to prepare the cutting edge. This method can deposit a thicker wear-resistant coating without affecting the cutting performance. Moreover, the layered design of the transition layer and the functional layer in the wear-resistant layer buffers the internal stress between materials with different hardness, thereby greatly improving the service life of the drill bit. At the same time, the drill bit has better stability and higher drilling quality. Attached Figure Description

[0015] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on the structures shown in these drawings without creative effort.

[0016] Figure 1 This is a schematic diagram of the tool base structure in one embodiment of the present invention; Figure 2 This is a distribution diagram of CPK values ​​for holes drilled with a cutting tool of different numbers in one embodiment of the present invention.

[0017] Explanation of reference numerals in the attached figures: 10. Drill bit head; 20. UC part; 30. Base.

[0018] The realization of the objective, functional features and advantages of the present invention will be further explained in conjunction with the embodiments and with reference to the accompanying drawings. Detailed Implementation

[0019] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0020] It should be noted that if the embodiments of the present invention involve directional indicators (such as up, down, left, right, front, back, etc.), the directional indicators are only used to explain the relative positional relationship and movement of the components in a specific posture. If the specific posture changes, the directional indicators will also change accordingly.

[0021] Furthermore, if the embodiments of this invention involve descriptions such as "first" or "second," these descriptions are for descriptive purposes only and should not be construed as indicating or implying their relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined with "first" or "second" may explicitly or implicitly include at least one of those features. Additionally, the use of "and / or" or "and / or" throughout the text includes three parallel solutions. For example, "A and / or B" includes solution A, solution B, or a solution where both A and B are satisfied simultaneously. Furthermore, the technical solutions of the various embodiments can be combined with each other, but this must be based on the ability of those skilled in the art to implement them. When the combination of technical solutions is contradictory or impossible to implement, it should be considered that such a combination of technical solutions does not exist and is not within the scope of protection claimed by this invention.

[0022] The technical problem addressed in this application is that cutting tools such as micro drills or drill bits are widely used in PCB board drilling. With increasing processing efficiency and changes in processed materials, higher demands are placed on the wear resistance of drill bit coatings. For example, conventional drill bits cannot meet the needs of thicker or more complex PCB boards. Related technologies improve drill bit lifespan and wear resistance by increasing the thickness of the wear-resistant coating. However, the internal stress of the wear-resistant coating increases with the coating thickness. When the coating thickness reaches approximately 2.0 μm, it damages the cutting edge of the drill bit, significantly weakening its cutting performance and affecting normal drilling. Therefore, a method for manufacturing drill bits that significantly extends their lifespan while retaining their cutting performance is urgently needed.

[0023] It should be noted that conventional techniques involve first slotting the tool substrate to form the main structure of the cutting edge and chip removal grooves, and then depositing a wear-resistant coating on the surface of the drill bit head on the tool substrate to produce the drill bit. As the thickness of the wear-resistant coating increases, the wear resistance of the drill bit improves, and the life of the drill bit increases accordingly. At the same time, the internal stress of the wear-resistant coating also increases significantly with the increase of the coating thickness. When the coating thickness increases to about 2.0 μm, it will damage the cutting edge of the drill bit, making the drill bit unusable and resulting in poor drilling quality. Therefore, the coating thickness of current micro drill bits used for PCB rigid board processing is only about 1.5 μm.

[0024] To address the aforementioned technical problems, this application proposes a method for preparing a cutting tool, the method comprising the following steps: S1. A wear-resistant coating is deposited on the surface of the tool substrate to obtain the tool intermediate; S2. Grooving is performed on the surface of the intermediate tool body obtained in step S1 to form a cutting edge and a chip removal groove, thus completing the preparation of the tool.

[0025] It should be noted that the technical solution in this application innovatively adopts a reverse process of "coating first and then grooving". By first depositing a wear-resistant coating on the smooth surface of the tool substrate, the stress in the coating is evenly distributed on the continuous surface without grooving, thus avoiding the stress concentration effect at the sharp cutting edge.

[0026] Furthermore, the cutting edge region formed by subsequent grooving is a composite structure consisting of the deposited wear-resistant coating and the substrate. The coating edge is in a natural transition state formed by machining, rather than the overlapping structure formed by coating deposition on the pre-made cutting edge in traditional processes. This preparation method eliminates the defects of cutting edge dulling and stress cracking caused by excessive coating thickness, allowing the deposition thickness to reach more than 2μm.

[0027] By adopting the above technical solutions, the wear life of the drill bit is greatly improved while maintaining its sharp cutting performance, and it can also effectively alleviate common industry problems such as chipping and delamination caused by thick coatings.

[0028] In one embodiment, reference is made to Figure 1 The tool body includes a drill bit head, a UC section and a base connected in sequence; In one embodiment, the length of the drill bit head is 0.5mm to 1.5mm; in another embodiment, the diameter of the drill bit head is 0.15mm to 0.5mm.

[0029] Understandably, the base is used for clamping and fixing, the drill bit head is used for cutting, and the UC part is used for rigidly connecting the base and the drill bit head; preferably, the diameter of the UC part is slightly smaller than the diameter of the drill bit head, so as to form a small gap during drilling and reduce friction with the hole wall.

[0030] By adopting the above-mentioned structural and dimensional design, it is possible to ensure that a sharp cutting edge free of coating stress defects can be obtained through subsequent fine grinding, based on a wear-resistant coating of 2.0μm or even thicker.

[0031] In one embodiment, the coaxiality between the drill bit head and the spindle of the tool body does not exceed 8 μm. In another embodiment, the coaxiality between the UC section and the spindle of the tool body does not exceed 8 μm.

[0032] In a preferred embodiment, the coaxiality between the drill bit head and the spindle of the tool body does not exceed 5 μm. In another preferred embodiment, the coaxiality between the UC section and the spindle of the tool body does not exceed 5 μm.

[0033] Understandably, the tool substrate has a complete, continuous, and highly coaxial cylindrical outer surface, which provides an ideal base for the subsequent formation of a wear-resistant coating of uniform thickness. This avoids stress imbalance and further coaxiality degradation caused by uneven coating deposition due to structural asymmetry (such as pre-existing chip grooves).

[0034] It should also be noted that high-precision coaxiality requirements are beneficial for simultaneously ensuring extremely high drilling positioning accuracy and hole wall quality under conditions of thick wear-resistant coatings. Specifically, under high-speed rotation of the drill bit, any tiny coaxiality error will lead to huge centrifugal force, causing the drill bit to swing, which in turn leads to enlargement of the drill hole diameter, positional displacement, rough hole wall or even crescent-shaped damage, or premature fatigue fracture of the drill bit itself due to alternating stress.

[0035] Furthermore, the pre-coating followed by grooving process of this invention helps to ensure and improve the coaxiality of the final product. The substrate is a complete and symmetrical cylinder, and the coating stress is evenly distributed, minimizing the deformation caused by the coating process itself. Although the subsequent grooving process disrupts the local symmetry, because it is performed on a highly coaxial "coating-substrate" composite blank, it can ensure that the newly generated cutting edge and chip groove have extremely high positional accuracy relative to the spindle.

[0036] In a preferred embodiment, the roundness of the drill bit head is not less than 2 μm.

[0037] Specifically, roundness refers to the shape deviation of the actual machined drill bit tip cylindrical cross-section relative to an ideal circle. This roundness index is the result of testing and controlling the drill bit tip of the tool substrate before depositing the wear-resistant coating in step S1. The higher the roundness of the drill bit tip, the more uniformly reactive particles or plasma can reach and adhere to the substrate surface from all directions during subsequent chemical vapor deposition or physical vapor deposition processes. This directly determines the uniformity and consistency of the deposited wear-resistant coating thickness. A substrate with high roundness provides the geometric basis for forming a wear-resistant coating with uniform stress distribution.

[0038] In one embodiment, in step S1, a wear-resistant coating is deposited on the surface of the drill bit tip of the tool substrate to obtain a wear-resistant coating with a thickness of 4μm to 8μm. Specifically, the wear-resistant coating can be a multilayer composite structure.

[0039] Understandably, the wear-resistant coating of the drill bit in this application increases the coating thickness by more than 2 times, easily handling high-volume drilling of thick PCB boards with high glass fiber content and high abrasiveness. The sharpness of the cutting edge is not affected by the deposition process, but is entirely determined by the quality of the fine grinding process. Therefore, the cutting performance, chip removal capability, and drilling quality of the drill bit are all guaranteed.

[0040] In one embodiment, the wear-resistant coating comprises metallic and non-metallic elements; wherein the metallic elements include at least one of Cr, Al, Ti, V, Y, Nb, and Mo; and / or the non-metallic elements include at least one of Si, N, O, and C.

[0041] Preferably, the wear-resistant coating is a single-layer or multi-layer composite structure of nitrides, carbonitrides, or oxides composed of metallic and non-metallic elements. For example, the wear-resistant coating includes, but is not limited to, TiN, TiAlN, TiCN, AlTiN, AlCrN, CrN, TiSiN, AlCrSiN, TiAlSiN, or nanocomposite coatings doped with elements such as V, Y, and Nb.

[0042] The present invention also proposes a cutting tool, which is prepared by the above-described method. The cutting tool includes a cutting tool body and a wear-resistant coating disposed on the outer surface of the drill bit head of the cutting tool body, and the thickness of the wear-resistant coating is 4μm~8μm.

[0043] In one embodiment, a transition layer is further provided between the tool substrate and the wear-resistant coating, and the thickness of the transition layer is 0.3μm~0.5μm.

[0044] Specifically, the transition layer is disposed on the outer surface of the tool substrate, the wear-resistant coating is disposed on the outer surface of the transition layer, and the hardness of the transition layer is less than the hardness of the wear-resistant coating.

[0045] In this invention, a transition layer is provided on the outer surface of the tool substrate, and a wear-resistant coating is then provided on the outer surface of the transition layer. The transition layer, with a hardness lower than that of the wear-resistant coating, buffers the internal stress between the tool substrate and the wear-resistant coating. Without damaging the cutting edge of the tool substrate, the thickness of the wear-resistant coating can be greater than the coating thickness of micro drill bits used for hard plate machining in conventional technologies. With increased wear-resistant coating thickness, higher hardness and better wear resistance result in a significantly longer service life for the drill bit.

[0046] Furthermore, in order to improve the buffering effect of the transition layer between the tool substrate and the wear-resistant coating, the transition layer includes a first sub-transition layer, a second sub-transition layer and a third sub-transition layer stacked sequentially from the tool substrate outwards with gradually increasing hardness. The transition layer is configured as a multi-layer structure to improve the buffering effect, and the multi-layer sub-transition layers buffer the internal stress between adjacent layers one by one.

[0047] It should be noted that the sub-transition layer can be one, two, three or more layers. In this embodiment, the transition layer includes three sub-transition layers, specifically a first sub-transition layer, a second sub-transition layer and a third sub-transition layer that are stacked outward from the tool substrate and have gradually increasing hardness.

[0048] In a more specific embodiment, the hardness of the first sub-transition layer, the second sub-transition layer, and the third sub-transition layer are 8 GPa~12 GPa, 13 GPa~17 GPa, and 18 GPa~22 GPa, respectively.

[0049] In a more preferred embodiment, the hardness of the first sub-transition layer, the second sub-transition layer, and the third sub-transition layer are 10 GPa, 15 GPa, and 20 GPa, respectively, to achieve a uniform transition.

[0050] In a more specific embodiment, the thickness of the transition layer can be varied and is not limited to any particular type. In this embodiment, the thicknesses of the first sub-transition layer, the second sub-transition layer, and the third sub-transition layer are 0.1 μm to 0.2 μm, respectively.

[0051] In one embodiment, the wear-resistant coating comprises functional layers stacked sequentially from the transition layer outwards, with the hardness gradually increasing. By using multiple functional layers to buffer the internal stress between adjacent layers, the buffering effect is improved, preventing excessive internal stress from damaging the cutting edge of the tool substrate. Furthermore, the gradual increase in hardness from the inside out through the multiple functional layers results in a high hardness for the outermost functional layer and increases the thickness of the wear-resistant coating, thus providing excellent wear resistance.

[0052] In one embodiment, by buffering internal stress through a multi-layer structure, the thickness of the first and second functional layers is 2μm to 4μm without damaging the cutting edge of the tool substrate. It is worth noting that the thickness of the functional layers is not limited to 2.0μm to 3.5μm; with structural optimization, the thickness of the first and second functional layers can obviously exceed 4μm. As the thickness of the functional layers increases, the wear resistance of the drill bit improves, and the lifespan of the drill bit 100 increases. The preferred thickness of the first and second functional layers is 2μm to 4μm. PCB boards drilled using this drill bit have higher precision and a longer service life.

[0053] In a more specific embodiment, the hardness of the first functional layer and the second functional layer are 25 GPa~34 GPa and 35 GPa~45 GPa, respectively.

[0054] In a preferred embodiment, the hardness of the first functional layer and the second functional layer are 30 GPa and 38 GPa, respectively.

[0055] The present invention will be further illustrated below through specific embodiments: The raw materials, reagents, or devices used in the embodiments of this invention are all commercially available. Unless otherwise specified, this invention does not impose any restrictions on the source of raw materials.

[0056] Example 1 The method for preparing the cutting tool in Example 1 includes the following steps: S1. Select a tool substrate, wherein the length of the drill bit head is approximately 1.2 mm. First, deposit a first sub-transition layer, a second sub-transition layer, and a third sub-transition layer, each with a thickness of 0.1 μm, on the surface of the drill bit head. The material of the first sub-transition layer is TiAlN, and the element ratios of the different sub-transition layers are different, with corresponding hardnesses of approximately 10 GPa, 15 GPa, and 20 GPa, respectively. Then, deposit a first functional layer and a second functional layer, each with a thickness of 3 μm, on the surface of the third sub-transition layer. The material of the first functional layer is TiAlSiN, and the material of the second functional layer is AlTiNbN, with corresponding hardnesses of 30 GPa and 38 GPa, respectively. The deposition of the transition layer and the wear-resistant coating is completed, and the tool intermediate body is obtained. S2. Grooving is performed on the surface of the intermediate tool body obtained in step S1 to form a cutting edge and a chip removal groove, thus completing the preparation of the tool.

[0057] The cutting tool in Example 1 is a UC-type grooving tool with two symmetrical cutting edges and two chip grooves, a helix angle of 42 degrees, and a core diameter approximately 70% of the outer diameter. The outer diameter of the tool substrate before the deposition of the wear-resistant coating in Example 1 is approximately 0.2 mm, and the groove length is 3.5 mm to 6.5 mm.

[0058] The friction coefficient of the tool surface obtained in Example 1 is approximately 0.4.

[0059] Performance testing (1) The cutting tool prepared in Example 1 was used to drill a plate (1.6mm thick, 6 layers of copper, 1oz per layer, two plates stacked together) with part number Shengyi S1141 as the material to be processed. The drilling conditions were: rotation speed 150KRPM (150,000 revolutions per minute); drilling speed 40mm / s; first, 10,000 holes were drilled, and the drill bit at this time was recorded as NEW-10000, and the CPK value of the hole position was measured; then the cutting edge was re-grinded, and the grinding amount was controlled at 0.01mm~0.03mm; the second 1000 holes were drilled. For the first hole (0 holes), the drill bit is designated M1-10000, and the CPK value at the hole position is measured. The cutting edge is then re-grinded, with the grinding amount controlled between 0.01mm and 0.03mm. For the second hole (10000 holes), the drill bit is designated M2-10000, and the CPK value at the hole position is measured. The cutting edge is then re-grinded, with the grinding amount controlled between 0.01mm and 0.03mm. For the third hole (10000 holes), the drill bit is designated M3-10000, and the CPK value at the hole position is measured. See the detailed measurement results below. Figure 2 .

[0060] (2) The outer diameter (mm) of the drill bit distance from the tip of NEW-10000, M1-10000, M2-10000 and M3-10000 were measured respectively. See Table 1 for details.

[0061] Table 1

[0062] Through the Figure 2 Analysis shows that after drilling a total of 40,000 holes, the drill bit prepared in Example 1 still achieved a hole position CPK value, i.e., drilling accuracy, of 1.338, which is still higher than the industry standard of 1.33. This indicates that the service life of the drill bit prepared in Example 1 is as long as 40,000 holes.

[0063] Analysis of Table 1 shows that after drilling a total of 40,000 holes, the outer diameter of the drill bit prepared in Example 1 is still greater than 0.2 mm at a distance of 1.2 mm from the tip. This indicates that the tool body did not wear after drilling 40,000 holes.

[0064] The above description is merely an exemplary embodiment of the present invention and does not limit the patent scope of the present invention. Any equivalent structural transformations made using the contents of the present invention's specification and drawings under the technical concept of the present invention, or direct / indirect applications in other related technical fields, are included within the patent protection scope of the present invention.

Claims

1. A method for preparing a cutting tool, characterized in that, The method for preparing the cutting tool includes the following steps: S1. A wear-resistant coating is deposited on the surface of the tool substrate to obtain the tool intermediate; S2. Grooving is performed on the surface of the intermediate tool body obtained in step S1 to form a cutting edge and a chip removal groove, thus completing the preparation of the tool.

2. The method for preparing the cutting tool as described in claim 1, characterized in that, The tool body includes a drill bit head, a UC section, and a base connected in sequence; Wherein, the length of the drill bit head is 0.5mm~1.5mm; and / or, the diameter of the drill bit head is 0.15mm~0.5mm.

3. The method for preparing the cutting tool as described in claim 2, characterized in that, The coaxiality of the drill bit head and the spindle of the tool body does not exceed 8 μm; And / or, the coaxiality of the spindle of the UC section and the spindle of the tool base does not exceed 8 μm.

4. The method for preparing the cutting tool as described in claim 2, characterized in that, The roundness of the drill bit head is not less than 2μm.

5. The method for preparing the cutting tool as described in claim 2, characterized in that, In step S1, a wear-resistant coating is deposited on the drill bit head of the tool substrate to obtain a wear-resistant coating with a thickness of 4μm~8μm.

6. The method for preparing the cutting tool as described in claim 1, characterized in that, The wear-resistant coating is composed of metallic and non-metallic elements; The metallic element includes at least one of Cr, Al, Ti, V, Y, Nb, and Mo; and / or the non-metallic element includes at least one of Si, N, O, and C.

7. A cutting tool, characterized in that, The cutting tool is manufactured using the cutting tool preparation method according to any one of claims 1 to 6. The cutting tool includes a cutting tool substrate and a wear-resistant coating disposed on the outer surface of the cutting tool substrate, and the thickness of the wear-resistant coating is 4μm to 8μm.

8. The cutting tool as described in claim 7, characterized in that, A transition layer is provided between the tool substrate and the wear-resistant coating, and the thickness of the transition layer is 0.3μm~0.5μm.

9. The cutting tool as described in claim 8, characterized in that, The transition layer includes a first sub-transition layer, a second sub-transition layer, and a third sub-transition layer, each with a thickness of 0.1 μm to 0.2 μm, stacked sequentially from the tool substrate outwards; Wherein, the hardness of the first sub-transition layer is 8 GPa to 12 GPa; and / or, the hardness of the second sub-transition layer is 13 GPa to 17 GPa; and / or, the hardness of the third sub-transition layer is 18 GPa to 22 GPa.

10. The cutting tool as described in claim 8, characterized in that, The wear-resistant coating includes a first functional layer and a second functional layer, each with a thickness of 2μm~4μm, which are stacked sequentially from the transition layer outwards. Wherein, the hardness of the first functional layer is 25GPa~34GPa; and / or, the hardness of the second functional layer is 35GPa~45GPa.

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