TW201718134A - Rod shape member and cutting tool - Google Patents

Abstract

This invention provides rod shape member which is an elongated member made of a super hard alloy containing WC particles and Co, the member having a first end and a second end in a lengthwise direction. The first end has a first central portion at a central position with respect to the width of the first end, and the second end has a second central portion at a central position with respect to the width of the second end. The first central portion has a content of Co less than the content of Co in the second central portion. The rod shape member has an average KAM value of WC particles measured by the method of EBSD at the first central portion smaller than that at the second central portion.

Description

Rod and cutting tool

The present invention relates to a bar-shaped body and a cutting tool such as a drill and an end mill.

The elongated rod-shaped body is used as a structural member. For example, a blank composed of an elongated cylindrical rod-shaped body is processed by forming a sharp edge to be a cutting tool such as a drill and an end mill. A drill bit for use in the drilling process is well known as a soild drill having a cutting edge at the front end and a flute extending from the cutting edge. The drill is used for the drilling operation of a substrate on which, for example, an electronic component is to be mounted. An example of a rod-shaped body blank having a different composition component in the radial direction or the longitudinal direction is disclosed in Japanese Laid-Open Patent Publication No. 2012-526664 (Patent Document 1).

In recent years, there has been a demand for the blank to further improve its wear resistance and resistance to breakage.

One aspect of the present invention is an elongated rod body composed of a superhard alloy containing WC (tungsten carbide) particles and Co (cobalt) and having a first end portion and a second end portion in the longitudinal direction. Wherein the first end portion has a first central portion located at a center in the width direction, the second end portion having a second central portion located at a center in the width direction, and a content of Co in the first central portion is greater than a content of Co in the second central portion Less, and measured by the Electron BackScatter Diffraction (EBSD) method in the aforementioned WC particles using a scanning electron microscope (ie, SEM-EBSD) with a backscattered electron diffraction image system. In the measurement of the average KAM value (Kernel Average Misorientation), the average KAM value of the first central portion is smaller than the average KAM value of the second central portion.

1‧‧‧Drill (cutting tool)

2‧‧‧ Billets (blanks for cutting tools)

3‧‧‧ handle

5‧‧‧ cutting edge

6‧‧‧ trench

7‧‧‧ neck

8‧‧‧ drill body

11‧‧‧First area

12‧‧‧Second area

13‧‧‧ Third Area

14‧‧‧ fourth region

15‧‧‧Protruding

20‧‧‧Mold

21‧‧‧ Die casting mould

22‧‧‧Move

23‧‧‧Under the punch

24‧‧‧Upper punch

25‧‧‧ recess

30‧‧‧First raw material powder

33‧‧‧Second raw material powder

35‧‧‧Formed body

Fig. 1 is composed of Figs. 1A to 1D. Fig. 1A is a side view showing a blank as an example of the rod-like body of the embodiment. Fig. 1B is a view showing the distribution of the content of Co in the billet of Fig. 1A. Fig. 1C is a view showing the distribution of the content of Cr in the billet of Fig. 1A. Fig. 1D is a view showing the distribution of the content of V in the billet of Fig. 1A.

Fig. 2 is composed of Figs. 2A and 2B. Fig. 2A is a side view showing a modification of the blank of Fig. 1A, and Fig. 2B is a view showing a distribution of the content of Co in the blank of Fig. 2A.

Fig. 3 is a schematic view showing the configuration of a mold for an example of a method for producing a blank of Fig. 1.

Fig. 4 is a side view showing an example of the drill of the embodiment.

The rod shape will be described below based on the drawings. A blank for a cutting tool according to the present embodiment (hereinafter simply referred to as a blank, a so-called blank) Refers to the material before processing the finished product) as an example of a rod. Fig. 1A is a side view of the billet, and Figs. 1B to 1D are graphs showing the content of Co, the content of Cr (chromium), and the content of V (vanadium) in the billet, respectively. The portion drawn by a broken line in the first drawing shows an example of a cutting tool formed using a blank.

The blank 2 used in the drill 1 (an example of a cutting tool) of Fig. 1 is an elongated cylindrical shape composed of a superhard alloy containing WC particles and Co, and has a first end side in the longitudinal direction. The end portion (hereinafter referred to as end portion A) and the end portion on the second end portion side (hereinafter referred to as end portion B). When the blank 2 of the present embodiment is used for the drill 1, the cutting edge 5 is formed at the end portion on the first end side (hereinafter referred to as the end portion X), and then the end portion B of the blank 2 is joined to A shank 3 located at the end of the second end side of the drill 1 (hereinafter referred to as the end portion Y). The blank 2 can be joined directly to the handle 3 and can also be joined to the handle 3 via another member.

In the present embodiment, the cutting edge 5 is formed by grinding the end portion A of the blank 2, so that the end portion A of the blank 2 is located closer to the first end than the end portion X of the drill 1 forming the cutting edge 5. side.

According to the present embodiment, the end portion A of the blank 2 has a first central portion located at the center in the width direction (hereinafter referred to as a central portion A1), and the end portion B of the blank 2 has a second central portion located at the center in the width direction. (This will be referred to as the central part B1 below). Further, the content of Co in the center portion A1 _A Co content is less than the center portion B1 of Co in the Co _B.

In other words, in the state of the drill 1, the end portion X has a central portion located at the center in the width direction (hereinafter referred to as a central portion X1), and the end portion Y has a central portion located at the center in the width direction (hereinafter referred to as Yang Department Y1). Further, the content of Co in the central portion X1 is smaller than the content of Co in the central portion Y1.

When the distribution of the Co content is as described above, the wear resistance at the end portion X side of the cutting edge 5 can be improved, and the fracture resistance at the end Y side which is easily broken by the cutting tool such as the drill bit and the end mill can be improved. Sex.

In the present embodiment, the "width direction" means a direction perpendicular to the longitudinal direction of the blank 2, and the "central portion in the width direction" means a position half the length in the direction perpendicular to the longitudinal direction of the blank 2. That is, a region including the center of the width direction of the blank 2. The "content" in the present embodiment does not mean a value of an absolute amount, but a value of a content ratio (% by mass).

Further, according to the present embodiment, in the measurement of the average KAM value of the WC particles measured by the backscattered electron diffraction (EBSD) method using a scanning electron microscope with a backscattered electron diffraction image system, the center is measured. The average KAM value of the portion A1 is smaller than the average KAM value of the central portion B1. In other words, in the state of the drill 1, the average KAM value of the central portion X1 is smaller than the average KAM value of the central portion Y1.

As described above, the average KAM value of each central portion is less likely to have cracks on the side of the end portion A, the chipping resistance is improved, and the rigidity at the side of the end portion B is increased, and the blank is increased. 2 is not easy to flex. Therefore, when the blank 2 is formed as a cutting tool having the cutting edge 5 on the end portion X side and the shank portion 3 on the end portion Y side, the chipping resistance of the cutting edge 5 is improved and the rigidity of the end portion B can be improved. Therefore, the machining accuracy of the cutting tool can be improved.

In particular, when the average KAM value of the central portion A1 is 0.5 to 0.65° and the average KAM value of the central portion B1 is 0.75 to 0.92°, the chipping resistance of the end portion A and the rigidity of the end portion B can be further improved. When the cutting tool is formed, the chipping resistance and the machining accuracy of the cutting edge 5 can be further improved.

Here, "KAM (Kernel Average Misorientation)" means the difference in crystal orientation (that is, local azimuth difference) between adjacent measurement points measured by EBSD (Electron BackScatter Diffraction), KAM The value is related to the size of plastic cleformation and the like. Since the KAM system reflects local deformation and indexing density on a microscopic scale, the KAM value can be measured to confirm local plastic deformation on the microscopic scale. The average KAM value is a value obtained by measuring and averaging the KAM values of the respective positions in the observation area.

In the present embodiment, in the molded body before the billet 2 is sintered, the amount of Co added on the end portion A side is smaller than the amount of Co added on the end portion B side, and one part of Co is diffused during sintering. content of the center portion A1 of the blank 2 of Co _a Co content is less than the center portion B1 of Co in the Co _B. Since the amount of addition of Co on the end portion A side is smaller than the amount of addition of Co on the end portion B side, the amount of sintering shrinkage on the end portion A side is different from the amount of sintering shrinkage on the end portion B side. Therefore, although the deformation is likely to occur in the sintering step, the average KAM value can be obtained while the part of the WC particles existing on the end A side and the end B side is slightly plastically deformed by controlling the sintering conditions. Control is within the predetermined range.

The end portion A of the blank 2 of the present embodiment, except for the central portion In addition to A1, there is a first outer peripheral portion located on the outer circumference (hereinafter referred to as outer peripheral portion A2). The average KAM value of the WC particles in the outer peripheral portion A2 is smaller than the average KAM value of the W particles in the central portion A1, and when used as a rotary cutter, the machining accuracy of the cutting edge 5 can be improved, and the tool life can be extended.

Here, the term "outer peripheral portion A2" means a range in which the average KAM value can be analyzed including the end portion of the outer periphery of the end portion A. For example, the measurement area of the average KAM value may be a region having a width of 10% or less with respect to the width in the direction perpendicular to the longitudinal direction in the cross section along the longitudinal direction of the blank 2 .

In terms of the content of Co, when Co _A is 0 to 10% by mass and Co _B is 2 to 16% by mass, the blank 2 can maintain high wear resistance and defect resistance. The more desirable range of Co _A and Co _B varies depending on the processing conditions. For example, when the blank 2 is used as a drill for processing a printed circuit board, Co _A can be 1 to 4.9% by mass, and Co can be used. _B is 5 to 10% by mass.

When Co _B is 5% by mass or more, it is easy to densify the end portion B in a usual uniform composition, and coagulation portions of Co are less likely to occur in the billet 2 after sintering. Therefore, unevenness is less likely to occur in the distribution of Co. This is considered to be because when Co _B is 5 mass% or more, Co diffuses due to the capillary phenomenon of Co, so that the coagulation portion of Co is less likely to occur, and it tends to be in a uniform distribution state. Therefore, even if Co _{A is} relatively small at the end A side, it becomes a dense super hard alloy.

Further, when the ratio of Co _A to Co _B (Co _A /Co _B ) is 0.2 to 0.7, the hardness of the end portion A can be improved, and the fracture resistance of the blank 2 can be improved.

In addition, when the Co content in the outer peripheral portion A2 is defined as Co _AO , when the Co _{AO is} smaller than the Co _A indicating the content of Co in the central portion A1, the drill and the end mill in the cutting tool can be used. Rotating the cutter increases the wear resistance of the peripheral portion A2 which is the easiest to wear among the cutting edges 5.

In the present embodiment, the blank 2 may contain a Cr element and a V element in addition to WC and Co. Further, the blank 2 may further contain carbides of metals of Groups IV, V, and VI of the periodic table other than W, Cr, and V. When the blank 2 contains Cr, the corrosion resistance of the blank 2 can be improved, and when Co and Cr are contained, heat resistance can be improved. Further, Cr and V can suppress abnormal grain growth of WC particles, so that a superhard alloy having high strength can be stably produced.

V is also a component that suppresses grain growth of WC particles at the time of sintering. When the content of V on the side of the end portion A is small, it is difficult to suppress the grain growth of the WC particles on the side of the end portion A, and the average particle diameter of the WC particles is large. Therefore, on the side of the end portion A, the chipping resistance of the cemented carbide is improved. On the other hand, when the content of the V element is large on the side of the end portion B, the grain growth of the WC particles is suppressed on the end portion B side, and the average particle diameter of the WC particles is small. Therefore, on the side of the end portion B, the strength of the cemented carbide becomes high, and the fracture resistance of the drill bit 1 is improved.

The content V _A of V in the central portion A1 may be smaller than the content V _B of V in the central portion B1. Further, the blank 2 may have a region in which the content of _Cr changes from the central portion A1 to the central portion B1 with a slope S _Cr and the content of _V changes with a slope S _V . At this time, the slope S _{Cr is} smaller than the slope S _V , and the overall corrosion resistance of the blank 2 is good. Further, when the slope S _{V is} larger than the slope S _Cr , not only the hardness on the end portion A side is increased, but also the chipping resistance is improved, and the strength on the end portion B side is also increased, and the fracture resistance is improved.

In the present embodiment, the terminating portion A and the end portion B refer to the end portion of the blank 2, but specifically, it is possible to analyze the blank 2 by an EPMA (Electron Probe X-ray MicroAnalyzer) analysis method. The scope of the composition. The method of confirming the change of the composition in the longitudinal direction of the blank 2 is to measure and confirm the distribution of the content of each metal element in the longitudinal direction of the blank 2 by the EPMA analysis method. In the 1C and 1D drawings, the description of the measured value of the end portion of the correct composition that cannot be detected in the EPMA analysis of the blank 2 is omitted. In addition, in the second figure, the description of the distribution of Cr and V is omitted.

Cr _A indicating the content of Cr in the central portion A1 is 0.05 to 2% by mass, and Cr _B indicating the content of Cr in the central portion B1 is 0.1 to 3% by mass, and V _A indicating the content of V in the central portion A1. When the V _B of the content of V in the central portion B1 is 0.05 to 2% by mass, the corrosion resistance, heat resistance and strength of the blank 2 are improved.

At least a part of Cr is solid-solved in the bonded phase in the form of a metal, and is present in the form of Cr ₃ C ₂ or a composite carbide with other metals. At least a part of V is solid-dissolved in the bonded phase in the form of a metal, and can also exist in the form of VC or a composite carbide with other metals. However, compared with the Cr element, the amount of V dissolved in the binder phase is less. In the present embodiment, Cr _A and Cr _B convert the content of the Cr element into a value after Cr ₃ C ₂ , and V _A and V _B convert the content of the V element into a value after VC.

When the S _Cr is 0 to 0.1% by mass/mm, and the S _V is 0.1 to 0.5% by mass/mm, the corrosion resistance and heat resistance of the blank 2, the abrasion resistance at the end A side, and the chipping resistance are at the end. The breakage resistance of the B side will increase.

The method of measuring Co _A , Co _B , Cr _A , Cr _B , V _A , and V _B can measure the central portion A1 and the central portion by EPMA analysis in a state in which the blank 2 is divided into two halves along the longitudinal direction. The composition in B1 is confirmed. The composition analysis of the blank 2 from the end portion A to the end portion B was carried out on the central axis of the cross section parallel to the longitudinal direction. The distribution of the Cr content and the V content in the longitudinal direction of the blank 2 was measured by the EPMA analysis method, and then the slope at which the overall distribution of the blank 2 was brought to a straight line by the least square method was calculated as S _Cr and S _V .

Here, when the content of Cr in the outer peripheral portion of the blank 2 is larger than the content of Cr located in the inner portion of the outer circumference of 100 μm or more in the direction perpendicular to the longitudinal direction, the corrosion resistance of the blank 2 is further improved. The content of Cr in the outer peripheral portion refers to the content of Cr in the range in which the composition of the blank 2 can be analyzed by the EPMA analysis method on the outer periphery. In the present embodiment, the corner portion on the end portion A side of the cross section in which the blank 2 is divided into two halves in the longitudinal direction is referred to as the outer peripheral portion A2, and the content of Cr in the other peripheral portion A2 is measured.

When the average particle diameter a _A of the WC particles in the central portion A1 is larger than the average particle diameter a _B of the WC particles in the central portion B1, the abrasion resistance of the end portion A which is high in hardness and which is likely to be defective can be improved. Further, since the rigidity of the end portion B can be increased, the rod-shaped body is less likely to be bent. Therefore, when the blank 2 is used for the cutting tool having the cutting edge 5 on the end A side and the shank 3 on the end B side, not only the wear resistance of the cutting edge 5 but also the chipping resistance of the end portion A is obtained. It will be more improved, and the end damage resistance of the end B will be further improved.

The average particle diameter of the WC particles can be calculated from a scanning electron microscope (SEM) photograph by LUZEX analysis. The following method can also be used as another method of confirming the average particle diameter of WC particles. First, for the cross section of the blank 2, the orientation of the WC particles was observed by a backscattered electron diffraction (EBSD) method using a scanning electron microscope (ie, SEM-EBSD) with a backscattered electron diffraction image system. direction. The outline of each WC particle is determined by confirming the orientation direction of each WC particle. Then, the area of each WC particle was calculated from the contour of each WC particle, and the diameter when the area was converted into a circle was used as the particle diameter. Then, the average value of the particle diameters of the respective WC particles was taken as the average particle diameter.

Here, when the ratio (a _A /a _B ) of the average particle diameter a _A to the average particle diameter a _B is 1.5 to 4, the wear resistance and the defect resistance on the side of the end portion A can be made appropriate, and The breakage resistance of the side of the end portion B can be improved.

In the present embodiment, the measurement of the average particle diameter of the WC particles in the end portion A and the end portion B is performed from the first end to the second end of the blank 2 when the structure of the blank 2 is observed by SEM analysis. Pull out a straight line that spans over the length of more than 10 WC particles. Further, the region from the first end and the second end is a region that does not exceed the length of the width of the rod.

When the average particle diameter a _A of the WC particles in the central portion A1 is larger than the average particle diameter a _AO of the WC particles in the outer peripheral portion A2 in the width direction of the end portion A in the direction perpendicular to the longitudinal direction, the outer peripheral portion A2 is The defect resistance is improved, and the rigidity in the center portion A1 is increased.

The outer peripheral portion A2 refers to a thickness region in which the length of the outer peripheral surface of the end portion A of the blank 2 is 10% of the length in the width direction, and the central portion A1 refers to the width direction of the end portion A including the blank 2 . The center of the thickness is 10% of the width of the end A of the blank 2. In the present embodiment, the average particle diameter of the WC particles in the outer peripheral portion A2 which is the corner portion on the end portion A side in the cross section when the blank 2 is divided into two halves in the longitudinal direction is defined as a _AO .

When the average particle diameter a _A is 0.3 to 1.5 μm and the average particle diameter a _B is 0.1 to 0.9 μm, not only the chipping resistance of the end portion A but also the fracture resistance of the end portion B is further improved. When the blank 2 is used for the drill 1, the ideal range of the average particle diameter a _A is 0.4 to 0.7 μm, and the ideal range of the average particle diameter a _B is 0.15 to 0.5 μm.

The blank 2 may have a first region 11 whose content of Co changes from the central portion A1 to the central portion B1 by a slope S _1Co , and a side closer to the end portion B than the first region 11, from the central portion A1 to the central portion B1, the content of Co varies with the second region 12 of the slope S _2Co . In this case, when S _{1Co is} larger than S _2Co , it is possible to improve the toughness of the blank 2 by improving the wide range of toughness on the side B side while maintaining the high wear resistance of the end portion A side. .

In the first region 11, the content of Cr may vary by the slope S _1Cr , and the content of V may vary by the slope S _1V . Further, in the second region 12, the content of Cr may vary by the slope S _2Cr , and the content of V may vary by the slope S _2V .

The presence of the first region 11 and the second region 12 can be confirmed based on the distribution of the content of Co in the longitudinal direction of the blank 2. Then, the content of Cr and the content of V in the first region 11 and the second region 12 are measured, and the slope at the time of approaching the distribution in each region by the least square method is calculated, and this is taken as S _1Co , S _1Cr , S _1V , S _2Co , S _2Cr , S _2V . The slope is positive in the direction from the central portion A1 to the central portion B1, and is gradually decreased from the central portion A1 toward the central portion B1.

When the slope S _1Co is 0.2 to 1% by mass/mm and the S _2Co is 0 to 0.2% by mass/mm, the hardness on the end portion A side can be improved, and the fracture resistance of the blank 2 can be improved. The slope S _1Co in the first region 11 may not be constant within the region. In particular, in the first region 11 so that the S _1Co is greater near the first end of the case A where the end portion at a first end of a high abrasion resistance becomes, and the breakage resistance blank 2 will Become higher.

When the diamond coating layer (not shown) is to be coated on the surface of the blank 2, when the content of Co contained in the second region 12 is small, the content of Co which hinders the growth of the diamond crystal is small, so in the second In the region 12, the degree of crystallization of the diamond coating layer is increased, so that the hardness and adhesion of the diamond coating layer are improved.

Between the second region 12 and the first region 11, there may be a third region 13 in which the content of Co varies from the central portion A1 to the central portion B1 by a slope S _3Co . At this time, when the slope S _{3Co is} larger than the slope S _2Co , it is easy to control the slopes S _1Co and S _{2Co of the} first region 11 and the second region 12, and it is possible to further improve the fracture resistance at the end B side where the breakage is likely to occur. . When the slope S _3Co is 2 to 50% by mass/mm, the wear resistance at the end portion A side and the fracture resistance at the end portion B side can be improved.

Fig. 1D shows how the content of the V element changes in accordance with the change in the content of the Co element. That is, in the 1Dth diagram, the slope S _1V of the V element in the first region 11 is larger than the slope S _2V of the V element in the second region 12. Moreover, the slope S _3V of the V element in the third region 13 is larger than the slope S _1V of the V element in the first region 11.

On the other hand, in the first C-figure, the content of the Cr element does not change in accordance with the change in the content of the Co element, and the reason is unknown, but the value of the Cr content in the adjacent position is largely uneven, but Overall, it changes with a small slope.

The blank 2 can have a fourth region 14 _whose Co content changes with a slope S _4Co on the side _closer to the first end than the first region 11 as shown in Fig. 2 . In this case, the ratio of the slope of the slope S S _{1Co 4Co} case of small, high wear resistance can range attrition enlarged end portion A side.

Further, when the slope S _4Co is 0 to 0.5% by mass/mm and the content of Co in the fourth region 14 is 0 to 0.6% by mass, when the surface of the blank 2 is coated with the diamond coating layer, since the fourth region 14 is Since the content of Co contained therein is small, the degree of crystallization of the diamond coating layer on the surface of the fourth region 14 can be further improved. Therefore, the hardness and adhesion of the diamond coating layer are improved. At the boundary between the first region 11 and the fourth region 14, a bending point having a distribution of Co content may exist.

Assuming that the length of the first region 11 is L ₁ , the length of the second region 12 is L ₂ , the length of the third region 13 is L ₃ , and the length of the fourth region 14 is L ₄ , at L ₁ /L ₂ =0.3 In the case of ~3, the hardness of the end portion A can be improved and the fracture resistance of the blank 2 can be improved. In the case of L ₃ /L ₂ = 0.01 to 0.1, the adjustment of the content of Co in the second region 12 and the first region 11 is easy. In the case of L ₄ /L ₂ =0 to 0.05, the densification of the cemented carbide of the end portion A can be more stably promoted. In the case where L ₄ /L _{2 is} larger than 0.05 and there is a portion where the fourth region 14 is not densified, a part of the fourth region 14 can be polished and removed while the drill 1 is being produced.

The components of the first region 11, the second region 12, the third region 13, and the fourth region 14 can be measured at the central portion in the width direction of the blank 2 of each region.

The content of the Co content of the end portion of the outer peripheral portion A is Co _AO A than the end of the central portion _A of Co Co is small, can improve the cutting edge 5 in the end mill or a drill bit, etc. The rotary tool wear easiest Wear resistance of the outer peripheral portion.

In the first and second figures, the blank 2 has a projection 15 located further outward than the end portion A in the longitudinal direction. The protrusion 15 is formed into a shape having a smaller diameter than the end portion A. That is, the diameter d _{c of the} protrusion 15 is smaller than the diameter d _{A of the} end portion A. Since the projections 15 can be easily formed and the front end portion of the drill 1 can be formed by forming the sharp edges in the projections 15, the processing cost is less wasted.

When the projections 15 are hemispherical as shown in Figs. 1 and 2, even if the blanks 2 collide with each other when the blank 2 is put into the joining device, the projections 15 can be prevented from being damaged, and the projections 15 can be prevented from being damaged. The case of blank 2 . In the present embodiment, the protruding portion 15 is coupled to the root portion side of the end portion A, and is connected to the R surface in a cross-sectional view. Therefore, it is suppressed that the load is concentrated on the end portion of the lower punch 23 at the time of molding of the formed body 35, and the lower punch 23 is broken.

Here, when the diameter d _A of the end portion A of the blank 2 and the diameter d _B of the end portion B of the blank 2 are both 2 mm or less, and the length in the longitudinal direction is L, the ratio of L to d _A (L) /d _A ) In the case of 3 or more, it is easier to adjust Co _A and Co _B in the sintered billet 2 to a predetermined value. In other words, when the ratio (L/d _A ) is large, even if Co diffuses during sintering, it is easy to sufficiently ensure the difference between Co _A and Co _{B in} the blank 2 . _A more desirable range of the ratio (L/d _A ) is 4 to 10.

The billet 2 may be in an unpolished state after the sintering, but in order to improve the positional accuracy of the billet 2 when the billet 2 is held in the step of joining the billet 2 to the handle 3, the billet 2 after sintering may be used. The outer peripheral surface is centerlessly processed.

Further, when the preferred size of the blank 2 is to be used as a drill for processing a printed circuit board, d _A and d _B are 0.2 to 2 mm, and the length L is 3 to 20 mm. _A more desirable range of d _A is 0.3 to 1.7 mm. In other applications, there is also a case where d _A exceeds 2 mm, and the ideal range of d _A in such a case is 0.2 to 20 mm, and L = 3 to 50 mm.

In the present embodiment, the drill 1 for drilling a printed circuit board is disclosed as an example of a cutting tool. However, the present invention is not limited thereto, and any body having an elongated shape may be used. For example, a cutting tool for turning machining such as a metal working drill, a medical drill, an end mill, or a throw away chip for inner diameter machining can be applied. Further, the rod-shaped body such as the blank 2 can be used as a wear-resistant material or a sliding member in addition to the cutting tool. The rod body is more suitable for processing to a predetermined shape even when used as a material or member other than the cutting tool, and the region including the end portion A is in a state where the end portion B is fixed. Use in contact with the target material.

(Manufacturing method of blank)

Next, a method of producing the blank 2 having the projections 15 will be described as an example of a method of producing a blank. First, a raw material powder for producing a WC powder such as a cemented carbide (this superhard alloy is to be a blank 2 and a cutting tool (drill 1)) is prepared. In the present embodiment, two types of raw material powders are blended.

That is, the first raw material powder 30 required for forming the portion of the blank 2 including the end portion A where the projection 15 is located, and the second raw material required for the portion for forming the side of the end portion B of the blank 2 are prepared. Powder 33. The first raw material powder 30 contains WC powder as a raw material powder. The first raw material powder 30 may also contain Co powder as a raw material powder.

The second raw material powder 33 contains WC powder and Co powder as a raw material powder. The content of the Co powder in the first raw material powder 30 is smaller than the content of the Co powder in the second raw material powder 33. The mass ratio of the content of the Co powder in the first raw material powder 30 to the content of the Co powder in the second raw material powder 33 is 0 to 0.5, particularly 0 to 0.3.

The first raw material powder 30 and the second raw material powder 33 may contain, in addition to the WC powder, Cr ₃ C ₂ powder, VC powder, or Co powder. Further, in addition to the powder described above, each of the first raw material powder 30 and the second raw material powder 33 may further contain carbonization of metals of Groups IV, V, and VI of the periodic table other than WC, Cr ₃ C ₂ , and VC. Addition of any of the materials, nitrides, and carbonitride powders.

For example, the adjustment of the WC powder in the first raw material powder 30 The blending amount is 90 to 100% by mass, the blending amount of the Co powder is 0 to 8% by mass, and the total amount of the additive is 0 to 5% by mass. The blending amount of the WC powder in the second raw material powder 33 is 65 to 95% by mass, the blending amount of the Co powder is 5 to 30% by mass, and the total amount of the additive is 0 to 10% by mass. Further, the end portion A to the end of the sintered billet 2 can be adjusted by making the average particle diameter of the WC powder in the first raw material powder 30 different from the average particle diameter of the WC powder in the second raw material powder 33. The characteristics of the distribution state, hardness and toughness of Co and other metal elements in Part B.

A slurry is prepared by adding a binder and a solvent to the powder after the above-described blending to prepare a slurry. Then, granulation was carried out to make the slurry into granules, and it was used as a powder for molding.

As shown in Fig. 3, a press molding die (hereinafter simply referred to as a die) 20 is prepared, and the above-described pellets are placed in a cavity 22 of a die dies 21 of the die 20. Then, the upper punch 24 is lowered from above the particles introduced into the cavity 22 of the die-casting mold 21, and pressurized to produce a molded body. In the present embodiment, as the top surface of the punching surface of the lower punch 23 of the cavity 22, there is a recess 25 for forming the projection 15.

The molding method in the present embodiment includes a step of introducing the first raw material powder 30 into a region including the concave portion 25 in the cavity 22, and a step of introducing the second raw material powder 33 into the cavity 22; a step of lowering the rod 24 from above and pressurizing the laminated body of the first raw material powder 30 and the second raw material powder 33 in the cavity 22; and removing the formed body 35 composed of the laminated body from the mold 20 .

The molded body 35 has a cylindrical shape, and the projections 15 and the ends thereof The content of Co in A is smaller than the content of Co in the end portion B. Therefore, it is easy to adjust the distribution of the content of Co to a predetermined form in the blank 2.

Further, when the bottom surface of the concave portion 25 is a curved surface, the molded body 35 can suppress the defect of the newly formed protruding portion 32, and the unevenness of the content of Co in the protruding portion 15 of the blank 2 after sintering can be suppressed, so that it can be easily Avoid local sintering defects. Further, the concave portion 25 and the protruding portion 15 may be omitted.

In order to obtain a sintered body having a diameter of 2 mm or less, for example, an additional load may be applied to the upper punch 24 to lower the position of the upper punch 24 by 0.1 to 2 mm from the holding position of the upper punch 24 during pressurization (ie, relative The length of the formed body is decreased by 0.1% to 20%, and the load of the lower punch 23 is reduced. When the molding conditions are as described above, the unevenness of the pressure applied to the molded body 35 is improved. Therefore, the shape of the blank 2 after the molded body 35 is sintered can be easily prevented from being broken when the molded body 35 is pulled out. For the intended shape.

At this time, as shown in Fig. 3, the diameter D _{A of the} molded body 35 on the lower punch 23 side can be made smaller than the diameter D _{B of the} upper punch 24 side. The ideal range of the ratio D _A /D _B in the present embodiment is 0.8 to 0.99.

Further, although not particularly illustrated, for example, the first raw material powder 30 and the second raw material powder 33 may be present in a smaller amount than the Co powder in the first raw material powder 30 and in the second raw material powder 33. The other raw material powder such as the third raw material powder having a content of Co powder having a large content of Co powder.

The formed body after press forming is taken out from the mold, and then After burning at a temperature of 1300 to 1500 ° C for 0.5 to 2 hours, it is subjected to vacuum heat equalization sintering (sinter-HIP) treatment to become a blank 2 . The sintering temperature is adjusted depending on the content of Co and the average particle diameter of the WC particles. In this case, in the present embodiment, the temperature increase rate from 1000 ° C to the sintering temperature during sintering is 4 to 7 ° C / min, and the pressure at the sintering temperature is 50 to 200 Pa. Further, the sinter-HIP is treated at a temperature of 5 to 20 ° C lower than the sintering temperature, and is treated at a pressure of 5 to 10 MPa. Thus, the content of Co at the end portion A and the end portion B can be easily adjusted.

Further, since the first raw material powder 30 and the second raw material powder 33 have different sinterability, the shrinkage ratio of the end portion A and the end portion B during sintering is different, and the molded body is deformed, and the shrinkage ratio of the end portion B is higher than that of the end portion B. Part A has a large shrinkage rate. That is, the sintering causes a portion of Co in the end portion B to diffuse toward the end portion A, so the end portion B will shrink more than the end portion A. Therefore, the shape of the sintered body tends to have a smaller diameter of the end portion B than the diameter of the end portion A.

Here, when the temperature increase rate is faster than 4 ° C / min, since the diffusion of Co during the sintering is prevented from being excessive, the difference in Co concentration in the billet 2 after sintering can be increased, and the central portion A1 can be easily made. The average KAM value is smaller than the average KAM value of the central portion B1. Further, depending on the case, it is sometimes easier to make the average particle diameter of the central portion A1 larger than the average particle diameter of the central portion B1. When the temperature increase rate is slower than 7 ° C / minute, the blank 2 can be well contracted, and the average KAM value of the central portion A1 can be easily made smaller than the average KAM value of the central portion B1. Further, depending on the case, it is sometimes easier to densify the WC particles at the end portion A.

In addition, the decompression pressure of the sintering temperature is above 50Pa. In the meantime, since the diffusion of Co during the sintering is prevented from being excessively performed, the difference in the Co concentration in the billet 2 after sintering can be increased, and the average KAM value of the central portion A1 can be easily made larger than the average KAM of the central portion B1. The value is small. When the pressure reduction pressure at the sintering temperature is 200 Pa or less, the blank 2 can be favorably shrunk, and the average KAM value of the central portion A1 can be easily made smaller than the average KAM value of the central portion B1. Therefore, it is easy to densify the WC particles at the end portion A.

Further, when the difference between the processing temperature of the sinter-HIP and the sintering temperature is larger than 5 ° C, the average KAM value of the central portion A1 can be easily made smaller than the average KAM value of the central portion B1. Further, depending on the case, it is sometimes easier to make the average particle diameter of the central portion A1 larger than the average particle diameter of the central portion B1. When the difference between the processing temperature of the sinter-HIP and the sintering temperature is 20 ° C or lower, the blank 2 can be favorably shrunk, and the average KAM value of the central portion A1 can be easily made smaller than the average KAM value of the central portion B1. Therefore, it is easy to densify the WC at the end portion A.

The molding step of the present embodiment is not limited to the press molding disclosed in the above embodiment, and may be performed by cold isostatic pressing, dry bag isostatic pressing, injection molding, or the like. To shape.

(Manufacturing method of cutting tool)

An example of a method of manufacturing the drill 1 for processing a printed circuit board using the blank 2 obtained by the above steps will be described below. First, tens or hundreds of blanks 2 are arbitrarily put into the joining device. The blanks 2 are arranged in a state in which the blanks 2 are aligned in the joint device. When having the protrusion 15, The projections 15 are confirmed by image data or the like to recognize the end portion A and the end portion B of the blank 2. According to the recognition result, the end portion A and the end portion B can be automatically arranged in a certain direction.

Then, the blanks 2 that are arranged side by side are automatically brought into contact with the separately formed members of the shank portion 3 and the neck portion 7, and then the two are joined by laser or the like. Then, the processed blank 2 is processed to form a sharp edge. At this time, the configuration of the drill 1 is as shown in Fig. 1, the end portion X is on the cutting edge 5 side of the drill 1, and the end portion Y is on the shank portion 3 side of the drill 1.

(cutting tool)

The blank 2 is processed to form a sharp edge, and a cutting tool such as a drill 1 is produced. The drill 1 of Fig. 4 is composed of a blank (processed portion) processed by forming a sharp edge, a neck portion 7 joined to the processed portion, and a rear end side of the neck portion 7 (upper side in Fig. 4). The handle 3 is formed. The processing portion has a cutting edge 5 at the end portion X and a groove 6 attached to the cutting edge 5. The processed portion and the neck portion 7 constitute a body 8. Therefore, it can also be said that the handle 3 is located on the rear end side of the drill body 8.

The cutting edge 5 has a central axis and is in contact with the material to be cut in a state of being rotated, and is required to have high chipping resistance and wear resistance in performance. The groove 6 has a function of discharging the chips generated by the processing to the rear, and the neck portion 7 is a portion that joins the processed portion and the shank portion 3 having different diameters from each other. The maximum diameter of the processed portion is set to, for example, 2 mm or less. The handle 3 can be used as part of fixing the drill bit 1 to the processing machine.

Although not specifically shown, a coating layer may be provided on the surface of the drill 1. The coating layer may be, for example, TiN, TiCN formed into a film by a PVD method. TiAlN, diamonds, diamond like carbon, and diamonds formed into a film by CVD.

The drill 1 may have a structure in which the neck portion 7 and the shank portion 3 are formed of a relatively inexpensive material such as steel, alloy steel or stainless steel, and then the blank 2 is joined to the front end of the neck portion 7. Further, the entire drill 1 may be composed of the blank 2. Further, the neck portion 7 is not essential, and the drill bit 1 may have a structure in which the blank 2 and the shank portion 3 are directly joined.

[Example 1]

A metal cobalt (Co) powder, a chromium carbide (Cr ₃ C ₂ ) powder, a vanadium carbide (VC) powder, and a tungsten carbide (WC) powder having a remaining ratio of an average particle diameter of 0.3 μm were blended at a ratio shown in Table 1. The two mixed powders of the first raw material powder and the second raw material powder shown in Table 1 were prepared. A slurry and a solvent were added and mixed to each mixed powder to prepare a slurry, and then a particle having an average particle diameter of 70 μm was produced by a spray dryer.

A mold having a 144 through holes as shown in Fig. 3 is prepared. First, the first raw material powder of Table 1 was placed in the mold, and then the second raw material powder of Table 1 was filled and subjected to press molding. A molded body in which the first raw material powder and the second raw material powder are laminated is formed by press molding, and then taken out from the mold. At this time, assuming that the diameter of the lower punch side is D _A , the diameter of the upper punch side is D _B , the length of the lower portion of the molded body is H _A , and the length of the upper portion of the molded body is H _B , the shape of the molded body is as shown in the table. 1 is shown.

The temperature was raised from 1000 ° C at the temperature increase rate shown in Table 2, and the molded product was sintered for one hour in the environment and the sintering temperature shown in Table 2, and then changed to the sinter-HIP shown in Table 2 (described in Table 2). for HIP) temperature, and a 30-minute sinter-HIP treatment at a pressure of 5 MPa to obtain a billet.

The diameter (d _A , d _B ) of the end portion A and the end portion B of the obtained billet was measured and described in Table 2. Further, the billet was divided into two halves along the longitudinal direction, and the change in the content of Co, the content of Cr, and the content of V from the end portion A to the end portion B was measured by EPMA analysis, and the first region to the fourth region were confirmed. The presence or absence of the area, slope, and length. Further, the content of Co in the outer peripheral portion was measured for the end portion A of the billet. The results are shown in Tables 2 to 5. Further, the average particle diameter of the WC particles in the central portion A1, the outer peripheral portion A2, and the central portion B1 was measured by the EBSD method.

The measurement of KAM by the EBSD method was carried out as follows. First, the length of the billet was buff-polished using a colloidal silica, and the measurement area was divided into quarters using an EBSD (Model JSM7000F) manufactured by Oxford Instruments. Area (pixel). For each of the divided regions, the Kikuchi Pattern is obtained from the reflected electrons of the electron beams incident on the surface of the sample to measure the orientation of each pixel. The measured orientation was analyzed using the analysis software of JSM7000F, and various parameters were calculated.

The observation conditions were as follows: the acceleration voltage was 15 kV, and the measurement area was set to be 60 μm in width × 5 μm in depth of the surface of the blank, and the distance between adjacent pixels (step size) was set to 0.1 μm. A case where the difference in orientation between adjacent pixels is 5 or more is regarded as a grain boundary. KAM calculates a certain pixel in a grain and is adjacent to a region that does not exceed the grain boundary. The average of the difference in orientation of the pixels is then measured as the average of all the pixels constituting the entire measurement area. The above average KAM value was measured for any three fields of view and then evaluated for the average value. The results are shown in Table 5.

Then, after the outer peripheral portion of the blank is subjected to centerless processing, it is arbitrarily placed in the joining device, and the direction of the protruding portion of the blank is recognized in the joining device, and the end portion A and the end portion B of each blank are arranged in the same In the direction, the end portion B of the blank is brought into contact with the shank portion to be joined, and then a portion forming a sharp edge is applied to the portion including the end portion A of the blank to prepare a drill.

For the obtained drill, the drilling test was performed under the following conditions. The results are shown in Table 5.

(Drilling processing test conditions)

Being cut: FR4, 0.8mm thick, three overlapping

Drilling shape: 0.25mm

Speed: 160krpm

Feed rate: 3.2m/min

Evaluation items: the number of products that can be holed (the) and the clearance surface of the drill bit after testing (μm)

As is apparent from Tables 1 to 5, the sample I-14 having the same Co _A and Co _{B had a} large clearance width of the clearance surface, and the sample I-15 was insufficient in sintering and the first hole was drilled to have a defect (initial defect). Further, the average KAM value (A) of the central portion A1 is the same as the average KAM value (B) of the central portion B1, and the average particle diameter a _A of the WC particles in the central portion A1 and the average particle size of the WC particles in the central portion B1. The samples I-16 to I-22 having the same diameter a _B have lower chipping resistance, and the hole position accuracy is lowered, and the number of processes is reduced. Further, in the samples I-16 to I-22, since the average particle diameter a _A of the WC particles in the central portion A1 is the same as the average particle diameter a _B of the WC particles in the central portion B1, the clearance surface has a large abrasion width and is processed. The number is also small.

On the other hand, in the samples I-1 to I-13 and I-23 in which the Co _{A is} smaller than Co _B and the average KAM value of the central portion A1 is smaller than the average KAM value of the central portion B1, the clearance width of the clearance surface is small. And the number of processing is large. Among them, in particular, the average KAM value of the central portion A1 is 0.50 to 0.65°, and the average KAM value of the central portion B1 is 0.75 to 0.92° for the samples I-1, I-2, and I-7 to I-13. More is more.

Further, the average KAM value (AO) of the WC particles in the outer peripheral portion A2 is smaller than the average KAM value of the WC particles in the central portion A1, and the number of the samples is I-1 to I-3 and I-7 to I-13. It is also more.

Further, the number of samples of the samples I-1, I-2, I-7, I-8, and I-10 to I-13 having a ratio (Co _A /Co _B ) of 0.2 to 0.7 was large. Further, the samples A-1 to I-4, I-6 to I-13, and I-23 having an average particle diameter a _{A of the} central portion A1 larger than the average particle diameter a _{B of the} central portion B1, and the remaining widths of the other gaps are larger. Small, the number of processing is large. The average particle diameter a _{A of} any of the samples was in the range of 0.3 to 1.5 μm, and the average particle diameter a _B was in the range of 0.1 to 0.9 μm. In particular, the samples I-1 to I-3 and I-7 to I-13 having a ratio of the average particle diameter a _A to the average particle diameter a _B (a _A / a _B ) of 1.5 to 4 were many in number.

Further, samples I-1 to I-4, I-7, I-9, and I-11 to I- having a ratio of the average particle diameter a _AO to the average particle diameter a _A (a _AO /a _A ) of 1.1 to 2 were used. 13, the remaining gap wear width is smaller, the number of processing is more.

Further, each of the samples I-1 to I-12 has a second region having a slope S _2Co and a first region having a slope S _1Co larger than the slope S _2Co , and the clearance width of the clearance surface is small, and the number of processing is large. In particular, the sample I-1, I-2, and I-6 to I-12 having a slope S _1Co of 0.2 to 1% by mass/mm and a slope S _2Co of 0 to 0.2% by mass/mm have a small clearance width of the clearance surface. .

[Embodiment 2]

Using the raw material powders used in Example 1, the formed bodies of Table 6 were produced and sintered under the conditions of Table 7. This blank is then used to make the drill bit. For the obtained drill, the drilling test was performed under the following conditions. The results are shown in Tables 7-10.

(Drilling processing test conditions)

Being cut: FR4 material, 24 layers, 3.2mm thick, one piece

Drilling shape: 0.25mm

Speed: 160krpm

Feed rate: 3.2m/min

Evaluation items: the number of products that can be machined (the) and the clearance width of the clearance surface of the drill after testing (μm)

It can be seen from Tables 6 to 10 that the sample A-1 to II-4 in which the Co _{A is} smaller than Co _B and the average KAM value of the central portion A1 is smaller than the average KAM value of the central portion B1, and the remaining gap wear width is small, and processing is performed. There are more. In the samples II-1 to II-4, the average particle diameter a _{A of} the central portion A1 was larger than the average particle diameter a _{B of the} central portion B1.

[Example 3]

Using the raw material powders used in Example 1, the molded bodies of Table 11 were produced and sintered under the conditions of Table 12. This blank is then used to make the drill bit. For the obtained drill, the drilling test was performed under the following conditions. The results are shown in Tables 12-15.

(Drilling processing test conditions)

Being cut: FP4 material, 0.06mm thick, 10 overlapping

Drilling shape: 0.105mm

Speed: 300krpm

Feed rate: 1.8m/min

Evaluation items: the number of products that can be machined (the) and the clearance width of the clearance surface of the drill after testing (μm)

As can be seen from Tables 11 to 15, samples III-1 to III-3 in which Co _{A is} smaller than Co _B and the average KAM value of the central portion A1 is smaller than the average KAM value of the central portion B1, and the remaining gap wear width is small, and processing is performed. There are more. In the samples III-1 to III-3, the average particle diameter a _{A of} the central portion A1 was larger than the average particle diameter a _{B of the} central portion B1.

1‧‧‧Drill (cutting tool)

2‧‧‧ Billets (blanks for cutting tools)

3‧‧‧ handle

5‧‧‧ cutting edge

6‧‧‧ trench

7‧‧‧ neck

8‧‧‧ drill body

15‧‧‧Protruding

Claims (12)

A rod-shaped body is a rod-shaped body composed of a superhard alloy containing WC particles and Co and having a first end portion and a second end portion in a longitudinal direction, wherein the first end portion has a first central portion located at a center in the width direction, the second end portion having a second central portion located at a center in the width direction, and a content of Co in the first central portion is smaller than a content of Co in the second central portion And in the measurement of the average KAM value of the WC particle measured by the backscattered electron diffraction (EBSD) method using a scanning electron microscope with a backscattered electron diffraction image system, the first central portion The average KAM value is smaller than the average KAM value of the second central portion described above. The rod-shaped body according to claim 1, wherein the first end portion further has a first outer peripheral portion on the outer circumference, and the average KAM value of the first outer peripheral portion is larger than that in the first central portion The average KAM value of the aforementioned WC particles is small. The rod-shaped body according to claim 1 or 2, wherein the first central portion has an average KAM value of 0.50 to 0.65°, and the second central portion has an average KAM value of 0.75 to 0.92°. The rod-shaped body according to any one of claims 1 to 3, wherein an average particle diameter ratio of the aforementioned WC particles in the first central portion The WC particles in the second central portion have a large average particle diameter. The rod-shaped body according to claim 4, wherein a ratio of an average particle diameter of the WC particles in the first central portion to an average particle diameter of the WC particles in the second central portion is 1.5~ 4. The rod-shaped body according to the fourth aspect of the invention, wherein the average particle diameter of the WC particles in the first outer peripheral portion is larger than an average particle diameter of the WC particles in the first central portion. The rod-shaped body according to claim 6, wherein a ratio of an average particle diameter of the WC particles in the first outer peripheral portion to an average particle diameter of the WC particles in the first central portion is 1.1~ 2. The rod-shaped body according to any one of claims 4 to 7, wherein the WC particles in the first central portion have an average particle diameter of 0.3 to 1.5 μm, and the aforementioned second central portion The WC particles have an average particle diameter of 0.1 to 0.9 μm. The rod-shaped body according to any one of claims 1 to 8, wherein a ratio of a content of Co in the first central portion to a content of Co in the second central portion is 0.2 to 0.7. The rod-shaped body according to any one of claims 1 to 9, wherein the rod-shaped system has a second region on a side of the second end portion, the Co content is changed by a slope S _2Co And a first region on the side of the first end portion, wherein the content of Co changes by a slope S _1Co , and the slope S _1Co is larger than the slope S _2Co . The rod-shaped body according to claim 10, wherein the slope S _1Co is 0.2 to 1% by mass/mm, and the slope S _2Co is less than 0.2% by mass/mm. A cutting tool comprising a superhard alloy containing WC particles and Co, and having a long cutting tool having an end portion X having a cutting edge and an end portion Y at the shank side in a longitudinal direction, wherein The end portion X has a central portion X1 located at the center in the width direction, and the end portion Y has a central portion Y1 located at the center in the width direction, and the content of Co in the central portion X1 is larger than the content of Co in the central portion Y1. In the measurement of the average KAM value of the WC particle measured by the backscattered electron diffraction (EBSD) method using a scanning electron microscope with a backscattered electron diffraction image system, the central portion X1 is small. The average KAM value is smaller than the average KAM value of the aforementioned central portion Y1.