WO2017057266A1

WO2017057266A1 - Bar stock and cutting tool

Info

Publication number: WO2017057266A1
Application number: PCT/JP2016/078251
Authority: WO
Inventors: 尊史山川; 松下　滋
Original assignee: 京セラ株式会社
Priority date: 2015-09-29
Filing date: 2016-09-26
Publication date: 2017-04-06
Also published as: CN108136514A; TW201718134A; CN108136514B; JP6608945B2; JPWO2017057266A1; TWI619571B

Abstract

An elongated bar stock made of a cemented carbide containing tungsten carbide (WC) particles and cobalt (Co) and comprising a first edge and a second edge along the longitudinal direction, wherein the first edge has a first center portion positioned in the center in the width direction, and the second edge has a second center portion positioned in the center in the width direction. The Co content in the first center portion is less than the Co content in the second center portion, and for the measurement of an average kernel average misorientation (KAM) for WC particles measured with the electron backscatter diffraction (EBSD) method, the average KAM value in the first center portion is less than the average KAM value in the second center portion.

Description

Rod and cutting tool

This aspect relates to a rod-shaped body and a cutting tool such as a drill and an end mill.

The long rod-shaped body is used as a structural member. For example, a blank made of a long cylindrical rod-like body becomes a cutting tool such as a drill and an end mill by performing a cutting process. A solid drill having a cutting edge located at the tip and a flute groove extending from the cutting edge is known as a drill used for drilling. The drill is used, for example, in drilling a substrate on which electronic components are mounted. As an example of the rod-shaped body, JP 2012-526664 A (Patent Document 1) discloses a blank having a different composition in the radial direction or the longitudinal direction.

In recent years, blanks are required to have further improved wear resistance and breakage resistance.

This aspect is a long rod-shaped body made of a cemented carbide containing WC particles and Co and having a first end and a second end in the longitudinal direction, and the first end is in the width direction. The second end portion has a second central portion located in the center in the width direction, and the content of Co in the first central portion is the second central portion. In the measurement of the average KAM value measured by the electron beam backscatter diffraction (EBSD) method with a scanning electron microscope with a backscattered electron diffraction image system of the WC particles, while being less than the content of Co in the center part, The average KAM value in the first central portion is smaller than the average KAM value in the second central portion.

FIG. 1 is composed of FIGS. 1A to 1D. FIG. 1A is a side view of a blank which is an example of a rod-shaped body of the present embodiment. FIG. 1B is a diagram showing a distribution of Co content in the blank of FIG. 1A. FIG. 1C is a diagram showing a distribution of Cr content in the blank of FIG. 1A. FIG. 1D is a diagram showing a distribution of V content in the blank of FIG. 1A. FIG. 2 is composed of FIG. 2A and FIG. 2B. FIG. 2A is a side view of a variation of the blank of FIG. 1A. FIG. 2B is a diagram showing a distribution of Co content in the blank of FIG. 2A. It is a schematic diagram for demonstrating the structure of a metal mold | die about an example of the manufacturing method of the blank of FIG. It is a side view about an example of the drill of this embodiment.

The rod-shaped body will be described with reference to the drawings. A blank for a cutting tool in the present embodiment (hereinafter also simply referred to as a blank) is an example of a rod-shaped body. FIG. 1A is a side view of a blank, and FIGS. 1B to 1D are diagrams respectively showing distributions of Co content, Cr content, and V content in the blank. In addition, the part shown with the dotted line in FIG. 1A has shown an example of the cutting tool formed using a blank.

A blank 2 used in the drill 1 in FIG. 1 which is an example of a cutting tool has a long cylindrical shape made of a cemented carbide containing WC and Co, and is located on the first end side in the longitudinal direction. It has an end portion (hereinafter referred to as end portion A) and an end portion (hereinafter referred to as end portion B) located on the second end portion side. When using the blank 2 of this embodiment for the drill 1, the cutting edge 5 is formed in the edge part (henceforth the edge part X) located in the 1st edge part side, and the 2nd edge part in the drill 1 is used. The end B of the blank 2 is joined to the shank 3 located at the end on the side (hereinafter referred to as end Y). The blank 2 may be directly joined to the shank 3 or may be another member.

In the present embodiment, since the cutting edge 5 is formed by polishing the end A in the blank 2, the end A in the blank 2 is more than the end X where the cutting edge 5 in the drill 1 is formed. It is located on the first end side.

According to this embodiment, the edge part A of the blank 2 has the 1st center part (henceforth center part A1) located in the center of the width direction, and the edge part B of the blank 2 is the width direction. 2nd center part (henceforth center part B1) located in the center. The Co content Co _A in the central portion A1 is smaller than the Co content Co _B in the central portion B1.

From another point of view, in the state of the drill 1, the end X has a central portion (hereinafter, referred to as the central portion X1) located at the center in the width direction, and the end Y of the drill is in the width direction. The center part (henceforth the center part Y1) located in the center of is included. And Co content in center part X1 is less than Co content in center part Y1.

As a result, the wear resistance on the end X side having the cutting edge 5 can be increased, and the break resistance on the end Y side that is easily broken in a cutting tool such as a drill or an end mill can be increased. .

The width direction in the present embodiment refers to a direction perpendicular to the longitudinal direction of the blank 2, and the central portion in the width direction is half the length in the direction perpendicular to the longitudinal direction of the blank 2. This refers to a region including the center in the width direction of the blank 2. The “content” in the present embodiment is not a value indicating an absolute amount but a value indicating a content ratio (% by mass).

And according to this embodiment, in the measurement of the average KAM value measured by the electron beam backscatter diffraction (EBSD) method by the scanning electron microscope with the backscattered electron diffraction image system of the WC particles, the average in the central portion A1 The KAM value is smaller than the average KAM value in the central portion B1. From another viewpoint, in the state of the drill 1, the average KAM value in the central portion X1 is smaller than the average KAM value in the central portion Y1.

This makes it difficult for cracks to develop on the side of the end A and has high chipping resistance, and on the side of the end B, the rigidity is high and the blank 2 is difficult to bend. Therefore, when the blank 2 is a cutting tool having the cutting edge 5 on the end X side and the shank 3 on the end Y side, the chipping resistance of the cutting edge 5 is improved and the end B Therefore, the processing accuracy of the cutting tool can be increased.

In particular, when the average KAM value in the central portion A1 is 0.5 to 0.65 ° and the average KAM value in the central portion B1 is 0.75 to 0.92 °, chipping resistance in the end portion A And the rigidity at the end portion B can be further increased, and when a cutting tool is used, the chipping resistance and processing accuracy of the cutting blade 5 can be further increased.

Here, KAM (Karnel Average s Misorientation) is a local azimuth difference that is a difference in crystal orientation between adjacent measurement points measured by EBSD (Electron Backscatter Diffraction) method, and the KAM value is a plastic strain. Etc., and have a correlation with Moreover, since KAM reflects local deformation and transition density at the microscopic level, local plastic deformation at the microscopic level can be confirmed by measuring the KAM value. The average KAM value is obtained by measuring the KAM values at each position in the observation region and averaging them.

In this embodiment, in the formed body before firing the blank 2, the amount of Co added on the end A side is made smaller than the amount of Co added on the end B side, and part of Co is diffused during firing. Thus, in the blank 2, the Co content Co _A in the central portion A1 is made smaller than the Co content Co _B in the central portion B1. Since the addition amount of Co on the end A side is smaller than the addition amount of Co on the end B side, the firing shrinkage amount on the end A side is different from the firing shrinkage amount on the end B side. For this reason, distortion is likely to occur in the firing process, but by controlling the firing conditions, the average KAM value is obtained while leaving a small plastic strain in a part of the WC particles existing on the end A side and the end B side. It can be controlled within a predetermined range.

The end A in the blank 2 of the present embodiment further includes a first outer peripheral portion (hereinafter referred to as an outer peripheral portion A2) located on the outer periphery in addition to the central portion A1. When the average KAM value of the WC particles in the outer peripheral part A2 is smaller than the average KAM value of the WC particles in the central part A1, when used as a rotary tool, the machining accuracy of the cutting blade 5 is increased, and the tool life is increased. Can be extended.

Here, the outer peripheral portion A2 refers to a range in which the average KAM value can be analyzed including the outer peripheral end portion of the end portion A. For example, the measurement region of the average KAM value may be measured with 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.

Then, the content of Co, Co _A is 0 to 10 mass%, when the Co _B is 2 to 16 mass% can maintain a high abrasion resistance and fracture resistance of the blank 2. More desirable ranges of Co _A and Co _B vary depending on processing conditions. For example, when using the blank 2 as a drill for processing a printed circuit board, Co _{A is set} to 1 to 4.9% by mass and Co _B May be 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 normal uniform composition, and it is difficult to form Co agglomerated portions in the blank 2 after firing. Therefore, the Co distribution is less likely to be uneven. This is presumably because when Co _B is 5% by mass or more, Co diffuses due to the Co capillary phenomenon, so that Co agglomerates are difficult to form, and a uniform distribution state is likely to occur. As a result, a dense cemented carbide is obtained on the end A side even if Co _A is relatively small.

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

Further, when the Co content in the outer peripheral portion A2 is defined as Co _AO , when this Co _AO is less than Co _A indicating the Co content in the central portion A1, a drill or In a rotary tool such as an end mill, it is possible to improve the wear resistance in the outer peripheral portion A2 that is most easily worn among the cutting blades 5.

In this embodiment, the blank 2 may contain a Cr element and a V element in addition to WC and Co. Further, the blank 2 may contain carbides of

Group

4, 5, and 6 metals other than W, Cr, and V. When the blank 2 contains Cr, the corrosion resistance of the blank 2 can be increased, and when it contains Co and Cr, the heat resistance can be increased. Moreover, since Cr and V can suppress abnormal grain growth of WC particles, a cemented carbide with high strength can be stably produced.

V is also a component that suppresses grain growth of WC particles during firing. When the V content is small on the end A side, the grain growth of the WC particles becomes difficult to be suppressed on the end A side, and the average particle size of the WC particles increases. As a result, the chipping resistance of the cemented carbide is improved on the end A side. On the other hand, when the V content is large on the end B side, grain growth of the WC particles is suppressed on the end B side, and the average particle size of the WC particles is reduced. As a result, the strength of the cemented carbide increases on the end B side, and the breakage resistance of the drill 1 is improved.

The V content V _A in the central portion A1 may be less than the V content V _B in the central portion B1. Also, blank 2 may have a region where the V content is varied in slope S _V with Cr content toward the center portion A1 to the central portion B1 is changed in a slope S _Cr. At this time, when the slope S _Cr is smaller than the inclination S _V is corrosion resistance is improved over the entire blank 2. Further, improved when the inclination S _V is greater than the inclination S _Cr serves to improve the high and chipping resistance hardness at the side of the end portion A, the strength is high and breakage resistance in the side of the end portion B To do.

In addition, in this embodiment, although the edge part A and the edge part B point out the edge part of the blank 2, it specifically points out the range which can analyze the composition of the blank 2 by EPMA analysis. In order to confirm the composition change in the longitudinal direction of the blank 2, the distribution of the content of each metal element in the longitudinal direction of the blank 2 is measured and confirmed by EPMA analysis. In FIG. 1C and FIG. 1D, in the EPMA analysis of the blank 2, the measurement values at the ends where accurate composition measurement is not possible are omitted. In FIG. 2, the description of the distribution of Cr and V is omitted.

Cr _A indicating the content of Cr in the central part A1 is 0.05 to 2% by mass, Cr _B indicating the content of Cr in the central part B1 is 0.1 to 3% by mass, and in the central part A1 When _VA indicating the V content is 0 to 1% by mass and V _B indicating the V content in the central portion B1 is 0.05 to 2% by mass, the corrosion resistance and heat resistance of the blank 2 And the strength is high.

At least a part of Cr is dissolved as a metal in the binder phase, and in addition, it is present as a composite carbide with Cr ₃ C ₂ or other metals. V is at least partially dissolved as a metal in the binder phase, and may also be present as a composite carbide with VC or other metals. V has a smaller amount of solid solution in the binder phase than Cr element. In the present embodiment, Cr _A and Cr _B are values obtained by converting the Cr element content into Cr ₃ C ₂ , and V _A and V _B are values obtained by converting the V element content into VC.

When S _Cr is 0 to 0.1% by mass / mm and _SV is 0.1 to 0.5% by mass / mm, the blank 2 has corrosion resistance, heat resistance, and resistance at the end A side. High wear resistance and chipping resistance, and breakage resistance on the end B side.

_{_{_{_{Incidentally, Co A, Co B, Cr}}}} A, Cr B, V A, method of measuring _{V B} is in a state of being split in half along the blank 2 in the longitudinal direction, the center portion A1 and the central portion B1 by EPMA analysis It can confirm by measuring the composition in. The composition analysis from the end A to the end B of the blank 2 is measured on a central axis parallel to the longitudinal direction of the cross section. Calculating a distribution of the content and the V content in the longitudinal direction of the Cr of the blank 2 was determined by EPMA analysis, the slope when approximated to a straight line by the least square method for the entire distribution of the blank 2 S _Cr, as S _V To do.

Here, in the direction perpendicular to the longitudinal direction, when the Cr content in the outer peripheral portion of the blank 2 is larger than the Cr content in the portion located 100 μm or more from the outer periphery, Corrosion resistance is further improved. In addition, content of Cr in an outer peripheral part refers to content of Cr in the range which can analyze the composition of the blank 2 by EPMA analysis in an outer periphery. Moreover, in this embodiment, the corner | angular part by the side of the edge part A in the cross section which divided | segmented the blank 2 along the longitudinal direction was made into outer peripheral part A2, and it measured as content of Cr in this outer peripheral part A2. .

The average particle size a _A of WC particles in the central portion A1 is greater than the average particle size a _B of the WC grains in the central portion B1 is deficient higher hardness is the wear resistance of the prone end A Can be improved. Further, since the rigidity of the end portion B is increased, the rod-shaped body is not easily bent. Therefore, when the blank 2 is a cutting tool having the cutting edge 5 on the end A side and the shank 3 on the end B side, the wear resistance of the cutting edge 5 and the chipping resistance at the end A are shown. Is further improved, and breakage resistance at the end B is improved.

The average particle diameter of WC particles can be calculated from the SEM photograph by the Luzex analysis method. Moreover, you may use the following method as another method of confirming the average particle diameter of WC particle | grains. First, about the cross section of the blank 2, the orientation direction of WC particle | grains is observed with the electron beam backscattering diffraction (EBSD) method by a scanning electron microscope with a backscattering electron diffraction image system. The outline of each WC particle is specified by confirming the orientation direction of each WC particle. Then, the area of each WC particle is calculated based on the outline of each WC particle, and the diameter when this area is converted into a circle is taken as the particle diameter. And let the average value of the particle size of each WC particle be an average particle size.

Here, when the ratio (a _A / a _B ) between the average particle diameter a _A and the average particle diameter a _B is 1.5 to 4, the wear resistance and fracture resistance on the end A side Can be optimized, and breakage resistance on the end B side can be improved.

In this embodiment, the region for measuring the average particle diameter of the WC particles at the end A and the end B is a straight line from the first end to the second end of the blank 2 when the structure of the blank 2 is observed by SEM analysis. To obtain a region where the straight line crosses 10 or more WC particles. In addition, the regions from the first end and the second end are regions that do not exceed the width of the rod-shaped body.

Further, in the direction perpendicular to the longitudinal direction, when the average particle size a _A of WC particles in the central portion A1 is greater than the average particle diameter a _AO of WC particles in the outer peripheral portion A2 of the width direction of the end portion A The fracture resistance at the outer peripheral portion A2 is improved, and the rigidity at the central portion A1 is improved.

In addition, outer peripheral part A2 points out the thickness area | region of 10% of the length of the width direction from the outer peripheral surface in the edge part A of the blank 2, and center part A1 is the center in the width direction of the edge part A of the blank 2 And a thickness region of 10% of the width at the end A of the blank 2 is indicated. Moreover, in this embodiment, the average particle diameter of WC particle | grains in the outer peripheral part A2 which is a corner | angular part by the side of the edge part A in the cross section which divided the blank 2 in the longitudinal direction is defined as _aAO .

Further, 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, the chipping resistance of the end A is further improved, The breakage resistance of the end B is further improved. If the blank 2 is used to drill 1, the desirable range of the average particle size _{a A} is 0.4 ~ 0.7 [mu] m, preferably in the range of the average particle size _{a B} is 0.15 ~ 0.5 [mu] m.

Blank 2 is located in the 1st field 11 where content of Co changes with inclination _{S1Co as} it goes to center part B1 from central part A1, and the end B side rather than the 1st field 11, You may have 2nd area _| region 12 from which content of Co changes by inclination _{S2Co as} it goes to the center part B1 from part A1. At this time, when the slope S 1 _Co is larger than the slope S 2 _Co, the toughness in the wide area on the end B side can be increased while maintaining the wear resistance on the end A side high, and the blank 2 Breakage resistance can be improved.

In the first region 11, the Cr content may change with the slope S _1Cr , and the V content may change with the slope S _1V . In addition, in the second region 12, the Cr content may change with the slope S _2Cr , and the V content may change with the slope S _2V .

The presence of the first region 11 and the second region 12 can be confirmed by the distribution of Co content in the longitudinal direction of the blank 2. Then, the Cr content and the V content in the first region 11 and the second region 12 are measured, and the slopes when the distribution in each region is approximated by the least square method are expressed as S _1Co , S _1Cr , S _1V , _S _{_2Co,} S 2Cr, calculated as _{S 2V.} In addition, the direction where inclination becomes low toward center part B1 from center part A1 is made into plus, and the direction which becomes high toward center part B1 from center part A1 is made into minus.

When the slope S _1Co is 0.2 to 1% by mass / mm and the slope S _2Co is 0 to 0.2% by mass / mm, the hardness on the end A side can be improved and the blank 2 Breakage resistance can be improved. Note that the slope S _1Co in the first region 11 may not be constant within the region. In particular, in the first region 11, when the slope S _1Co increases as it approaches the first end located at the end A, the wear resistance at the first end is high, and the _break resistance of the blank 2 is high. Get higher.

When the surface of the blank 2 is coated with a diamond coating layer (not shown), if the Co content contained in the second region 12 is small, the Co content that hinders the growth of the diamond crystal is low. Since there are few, the crystallinity degree of a diamond coating layer becomes high in the 2nd area | region 12, Therefore The hardness and adhesiveness of a diamond coating layer improve.

Moreover, you may have the 3rd area _| region 13 where content of Co changes with inclination _{S3Co as} it goes to center part B1 from the center part A1 between the 2nd area _| region 12 and the 1st area _| region 11. At this time, when the inclination of the inclined _{S 3Co} is greater than the slope _{S 2Co} is inclined _S 1co of the first region 11 and the second region _12, it is easy to control the _{S 2Co,} breakage prone end The breakage resistance on the part B side can be further increased. When the slope S 3 _Co is 2 to 50 mass% / mm, both the wear resistance on the end A side and the _break resistance on the end B side can be improved.

FIG. 1D shows a change in the content of the V element so as to correspond to the change in the content of the Co element. That is, in FIG. 1D, 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. Further, 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 FIG. 1C, the change in the content of Cr element does not correspond to the change in the content of Co element, and the reason is unknown, but the value of Cr content at adjacent positions varies greatly. On the other hand, the overall change is small.

Furthermore, as shown in FIG. 2, on the side of the first end than the first region 11 may have a fourth region 14 in which the content of Co is changed in tilt S _4CO. At this time, when the inclination of the inclined S _4CO is smaller than the inclination of the inclined S _1co it may be able to increase the range of high wear resistance in the side of the end portion A.

Further, when the gradient S 4 _Co is 0 to 0.5 mass% / mm and the Co content in the fourth region 14 is 0 to 0.6 mass%, the diamond coating layer is formed on the surface of the blank 2. When coating is performed, the content of Co contained in the fourth region 14 is reduced, so that the crystallinity of the diamond coating layer on the surface of the fourth region 14 can be further increased. Therefore, the hardness and adhesion of the diamond coating layer are improved. An inflection point in the distribution of Co content may exist at the boundary between the first region 11 and the fourth region 14.

When the length of the first region 11 is L1, the length of the second region 12 is L2, the length of the third region 13 is L3, and the length of the fourth region 14 is L4, L1 / L2 = 0.3. In the case of ˜3, the hardness at the end A can be improved and the breakage resistance of the blank 2 can be increased. When L3 / L2 = 0.01 to 0.1, the adjustment of the Co content in the second region 12 and the first region 11 is easy. When L4 / L2 = is 0 to 0.05, densification of the cemented carbide at the end A can be more stably promoted. When L4 / L2 = is larger than 0.05 and there is a portion that is not densified in the fourth region 14, a part of the fourth region 14 is polished and removed when the drill 1 is manufactured. Also good.

In addition, what is necessary is just to measure the composition of the 1st area | region 11, the 2nd area | region 12, the 3rd area | region 13, and the 4th area | region 14 in the center part of the width direction of the blank 2, respectively.

Content Co _AO of Co in the outer peripheral portion of the end portion A, if less than the content Co _A of Co at the center of the end portion A, in the rotary tool drill or end mill, among the cutting edge 5 Abrasion resistance in the outer peripheral portion that is most easily worn can be increased.

In FIGS. 1 and 2, the blank 2 has a protruding portion 15 located on the outer side in the longitudinal direction from the end portion A. The protrusion 15 has a shape with a diameter smaller than that of the end A. That is, the diameter _{d A} of the end portion A, the diameter _{d c} of the projecting portion 15 is small. The protrusion 15 can be easily formed, and the tip of the drill 1 that has been bladed can be formed on the protrusion 15, so that the processing cost is not wasted.

As shown in FIGS. 1 and 2, when the projection 15 is hemispherical, the projection 15 may be lost even if the blanks 2 collide with each other when the blank 2 is randomly inserted into the bonding apparatus. It is suppressed, and it can also be controlled that other blank 2 is damaged by projection part 15. Moreover, in this embodiment, the base part side which the projection part 15 connects to the edge part A is connected by the R surface in the cross sectional view. Accordingly, it is possible to suppress the load from being concentrated on the end portion of the lower punch 23 during the molding of the molded body 35 and the lower punch 23 from being chipped.

Here, the diameter _{d B} of the B portion of the diameter _{d A} and a blank 2 of the end A of the blank 2 are both 2mm or less, when the longitudinal length is L, the ratio of L to _{d A} (L / d _{When A} ) is 3 or more, it is easy to adjust Co _A and Co _B to predetermined values in the blank 2 after firing. That is, when the ratio (L / d _A ) is a large value, even if Co diffuses during firing, it is easy to ensure a sufficient 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 blank 2 may be in a state where it is not polished after firing, but in order to increase the positional accuracy of the blank 2 when gripping the blank 2 in the step of joining the blank 2 to the shank 3, the outer periphery of the blank 2 after firing The surface may be centerless processed.

Note that preferable dimensions of the blank 2 are d _A and d _B of 0.2 to 2 mm and a length L of 3 to 20 mm when used as a drill for processing a printed circuit board. _A particularly desirable range for d _A is 0.3 to 1.7 mm. In other applications, d _A may exceed 2 mm, in which case the preferred range for d _A is 0.2-20 mm and L = 3-50 mm.

In this embodiment, the drill 1 used for drilling a printed circuit board is illustrated as a cutting tool. However, the present invention is not limited to this, and the drill 1 may have a long main body. That's fine. For example, the present invention can be applied as a cutting tool for turning such as a drill for metal processing, a medical drill, an end mill, and a throw-away tip for inner diameter processing. Further, the rod-like body such as the blank 2 can be used as an anti-wear material and a sliding member other than the cutting tool. Even when the rod-like body is used as a tool other than a cutting tool, the rod-like body is suitably used for an application in which the region including the end A is used in contact with the mating member in a state where the end B is fixed and processed. It is done.

(Blank manufacturing method)
As an example of a method for producing the blank, a method for producing the blank 2 having the protrusions 15 will be described. First, raw material powders, such as WC powder for producing the cemented carbide forming the blank 2 and the cutting tool (drill 1), are prepared. In this embodiment, two types of raw material powders are prepared.

That is, the 1st raw material powder 30 for producing the site | part containing the edge part A in which the projection part 15 in the blank 2 is located, and the 2nd raw material powder 33 for producing the edge part B side in the blank 2 are prepared. To do. The first raw material powder 30 contains WC powder as the raw material powder. The first raw material powder 30 may contain Co powder as the raw material powder.

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

Each of the first raw material powder 30 and the second raw material powder 33 may contain Cr ₃ C ₂ powder, VC powder, or Co powder in addition to the WC powder. In addition to the above powders, the first raw material powder 30 and the second raw material powder 33 are carbides, nitrides, and carbonitrides of periodic tables 4, 5, and 6 metals other than WC, Cr ₃ C ₂ , and VC, respectively. Any additive of the product powder may be contained.

For example, the amount of WC powder in the first raw material powder 30 is 90 to 100% by mass, the amount of Co powder is 0 to 8% by mass, and the total amount of additives is 0 to 5% by mass. . The amount of WC powder in the second raw material powder 33 is 65 to 95% by mass, the amount of Co powder is 5 to 30% by mass, and the total amount of additives is 0 to 10% by mass. . Further, the average particle size of the WC powder in the first raw material powder 30 and the average particle size of the WC powder in the second raw material powder 33 are made different from each other, so that the end portion A to the end portion B of the blank 2 after firing. It is also possible to adjust the distribution state, hardness, toughness and other characteristics of Co and other metal elements.

A slurry is prepared by adding a binder and a solvent to the above prepared powder. This slurry is granulated into granules and formed into molding powder.

As shown in FIG. 3, a press mold (hereinafter simply referred to as a mold) 20 is prepared, and the above granules are put into a cavity 22 of a die 21 of the mold 20. Then, the upper punch 24 is lowered from above the granules put into the cavity 22 of the die 21 and pressed to produce a molded body. In the present embodiment, the upper surface serving as the pressing surface of the lower punch 23 that is the bottom of the cavity 22 has a recess 25 for forming the protrusion 15.

The molding method according to the present embodiment includes a step of putting the first raw material powder 30 into a region including the recess 25 in the cavity 22, a step of putting the second raw material powder 33 into the cavity 22, and lowering the upper punch 24 from above. A step of pressurizing the laminated body of the first raw material powder 30 and the second raw material powder 33 put into the cavity 22 of the die 21, and a step of taking out the molded body 35 made of this laminated body from the mold 20. To do.

The molded body 35 has a cylindrical shape, and the Co content in the protrusion 15 and the end A is smaller than the Co content in the end B. As a result, it becomes easy to adjust the distribution of the predetermined Co content in the blank 2.

Moreover, when the bottom face of the recessed part 25 is a curved surface, in the molded object 35, while the chip | tip of the raw projection part 32 can be suppressed, the variation in Co content in the projection part 15 in the blank 2 after baking can be suppressed. For this reason, local sintering defects are easily avoided. Note that the recess 25 and the protrusion 15 may be omitted.

In the case of obtaining a sintered body having a diameter of 2 mm or less, for example, the position of the upper punch 24 from the holding position of the upper punch 24 at the time of pressurization is 0.1 mm to 2 mm, and 0.1 to the length of the molded body. An additional load may be applied to the upper punch 24 and the load on the lower punch 23 may be reduced so as to descend downward by a length of% to 20%. When the molding conditions are as described above, unevenness in pressure applied to the molded body 35 is improved, so that it is easy to avoid breakage when the molded body 35 is extracted, and the blank 2 after firing the molded body 35 is easy to avoid. The shape can be a predetermined shape.

At this time, as shown in FIG. 3, the diameter D _A of the lower punch 23 side of the molded body 35 may be smaller than the diameter D _B of the upper punch 24 side. _A desirable range of the ratio D _A / D _B in the present embodiment is 0.8 to 0.99.

Although not particularly illustrated, for example, between the first raw material powder 30 and the second raw material powder 33, the Co powder content in the second raw material powder 33 is smaller than the Co powder content in the first raw material powder 30. Other raw material powders such as a third raw material powder having a Co powder content higher than the content of Co may be present.

The molded body that has been pressure-molded is taken out of the mold, fired at 1300-1500 ° C. for 0.5-2 hours, and then subjected to sinter HIP treatment to become blank 2. The firing temperature is adjusted by the Co content and the average particle size of the WC particles. At this time, in this embodiment, the rate of temperature increase from 1000 ° C. during firing to the firing temperature is 4 to 7 ° C./min, and the reduced pressure at the firing temperature is 50 to 200 Pa. The sinter HIP is processed at a pressure 5 to 10 MPa at a temperature 5 to 20 ° C. lower than the sintering temperature. Thereby, the content of Co in the end A and the end B can be easily adjusted.

Moreover, since the sinterability of the first raw material powder 30 and the second raw material powder 33 is different, the shrinkage rate of the end A and the end B is different during firing, and the molded body is deformed, and the shrinkage rate of the end B Becomes larger than the contraction rate of the end portion A. That is, a part of Co at the end portion B diffuses toward the end portion A by firing, so that the end portion B contracts more than the end portion A. Accordingly, the diameter of the end portion B tends to be smaller than the diameter of the end portion A in the shape of the sintered body.

Here, when the heating rate is faster than 4 ° C./min, it is possible to avoid excessive diffusion of Co during firing, so that the difference in Co concentration in the blank 2 after sintering can be increased, and the center It is easy to make the average KAM value of the part A1 smaller than the average KAM value of the central part B1. Moreover, depending on the case, it is easy to make the average particle diameter of center part A1 larger than the average particle diameter of center part B1. When the rate of temperature increase is slower than 7 ° C./min, the blank 2 can be satisfactorily 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. In some cases, the WC can be easily densified at the end A.

In addition, when the decompression pressure at the firing temperature is 50 Pa or more, it is possible to avoid excessive diffusion of Co during firing, so that the difference in Co concentration in the blank 2 after sintering can be increased, and the central portion It is easy to make the average KAM value of A1 smaller than the average KAM value of the central portion B1. Further, when the reduced pressure is 200 Pa or less, the blank 2 can be satisfactorily 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. Therefore, it becomes easy to densify the WC at the end A.

Furthermore, when the difference between the processing temperature and sintering temperature of the sinter HIP 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. Moreover, depending on the case, it is easy to make the average particle diameter of center part A1 larger than the average particle diameter of center part B1. When the difference between the sintering HIP processing temperature and the sintering temperature is 20 ° C. or less, the blank 2 can be satisfactorily shrunk, and the average KAM value of the central part A1 is smaller than the average KAM value of the central part B1. Easy to do. Therefore, it becomes easy to densify the WC at the end A.

Note that the molding step in the present invention is not limited to the press molding shown in the above embodiment, but can be molded by cold isostatic pressing, dry bagging, injection molding, or the like.

(Manufacturing method of cutting tool)
An example of a method for producing a drill 1 for processing a printed circuit board using the blank 2 obtained by the above process will be described. Dozens or hundreds of blanks 2 are randomly placed in the bonding apparatus. The blank 2 is aligned in a state where the longitudinal direction is aligned in the bonding apparatus. When the protrusion 15 is provided, the protrusion 15 is confirmed by image data or the like, and the end A and the end B of the blank 2 are specified. Based on this specification, the end A and the end B can be automatically arranged in a certain direction.

Then, the arranged blanks 2 are automatically brought into contact with a member constituted by a shank 3 and a neck portion 7 which are separately prepared, and then joined by a laser or the like. Thereafter, blade joining is performed on the joined blank 2. At this time, as shown in FIG. 1, the drill 1 is configured such that the end X is on the cutting blade 5 side of the drill 1 and the end Y is on the shank 3 side of the drill 1.

(Cutting tools)
A cutting tool such as a drill 1 is produced by cutting the blank 2. The drill 1 in FIG. 4 is configured by a blank (machined part) that has been subjected to blade processing, a neck part 7 joined to the machined part, and a shank 3 positioned on the rear end side (upper side in FIG. 4) of the neck part 7. ing. The processed part has a cutting edge 5 located at the end X and a groove 6 following the cutting edge 5. A body 8 is constituted by the processed portion and the neck portion 7. Therefore, it can be said that the shank 3 is located on the rear end side of the body 8.

The cutting blade 5 is a portion that first contacts the work material while rotating around the central axis, and is required to have high chipping resistance and wear resistance. The groove 6 has a function of discharging chips generated by processing backward, and the neck portion 7 is a connecting portion that connects the processing portion and the shank 3 having different diameters. The maximum diameter of the processed part is set to 2 mm or less, for example. The shank 3 can be used as a part for fixing the drill 1 to the processing machine.

Although not particularly illustrated, a coating layer may be located on the surface of the drill 1. Examples of the coating layer include TiN, TiCN, TiAlN, diamond, diamond-like carbon, and diamond formed by the CVD method, which are formed by the PVD method.

The drill 1 may have a structure in which the neck 7 and the shank 3 are made of an inexpensive material such as steel, alloy steel, or stainless steel, and the blank 2 is joined to the tip of the neck 7. Further, the entire drill 1 may be constituted by the blank 2. Moreover, the neck 7 is not essential, and the drill 1 may have a configuration in which the blank 2 and the shank 3 are directly joined.

Metal cobalt (Co) powder, chromium carbide (Cr ₃ C ₂ ) powder, vanadium carbide (VC) powder, and the balance of tungsten carbide (WC) powder having an average particle size of 0.3 μm as shown in Table 1, Two kinds of mixed powders of the first raw material powder and the second raw material powder shown in Table 1 were prepared. To each mixed powder, a binder and a solvent were added and mixed to prepare a slurry, and granules having an average particle diameter of 70 μm were prepared with a spray dryer.

A mold shown in FIG. 3 provided with a die having 144 through holes was prepared. The first raw material powder of Table 1 was charged, and then the second raw material powder of Table 1 was filled and press-molded. A molded body in which the first raw material powder and the second raw material powder were laminated was molded by press molding and taken out of the mold. At this time, 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 part of the molded body is H _A , and the length of the upper part of the molded body is H _B. Indicated.

The molded body was heated from 1000 ° C. at the rate of temperature increase shown in Table 2 and fired for 1 hour in the atmosphere and firing temperature shown in Table 2. Then, the sintered HIP (shown as HIP in Table 2) temperature shown in Table 2 was obtained. It changed and the blank was obtained by performing the sinter HIP process for 30 minutes at the pressure of 5 MPa.

The obtained blank shown in Table 2 was measured end A, the diameter of the end portion B _{(d A,} d _B) a. Further, the blank was divided in half along the longitudinal direction, and changes in Co content, Cr content, and V content from end A to end B were measured by EPMA analysis. The presence, inclination, and length of the fourth region were confirmed from the region. Furthermore, about the edge part A of a blank, content of Co in an outer peripheral part was measured. The results are shown in Tables 2-5. Moreover, the average particle diameter of the WC particle | grains in center part A1, outer peripheral part A2, and center part B1 was measured by EBSD method.

The measurement of KAM by the EBSD method was performed as follows. First, the cross section in the longitudinal direction of the blank was buffed using colloidal silica, and then the measurement area was divided into square areas (pixels) using EBSD (model number JSM7000F) manufactured by Oxford. For each divided area, the Kikuchi pattern was obtained from the reflected electrons of the electron beam incident on the sample surface, and the orientation of the pixel was measured. The measured azimuth data was analyzed using JSM7000F analysis software, and various parameters were calculated.

Observation conditions were an acceleration voltage of 15 kV, a measurement area of 60 μm width × 5 μm depth on the blank surface, and a distance (step size) between adjacent pixels of 0.1 μm. A case where the orientation difference between adjacent pixels was 5 ° or more was regarded as a crystal grain boundary. KAM calculates the average value of misorientation between a certain pixel in the crystal grain and the adjacent pixel existing in the range not exceeding the crystal grain boundary, and measures the average KAM value as the average value in all the pixels constituting the entire measurement area. did. In addition, the measurement of the said average KAM value was measured about arbitrary 3 visual fields, and it evaluated by the average value. The results are shown in Table 5.

And after centerless-processing the outer peripheral part of this blank, it throws in in a joining apparatus at random, recognizes the direction of the protrusion part of a blank in a joining apparatus, and the edge part A and edge part B of each blank are the same A drill was produced by aligning the ends, bringing the end B of the blank into contact with the shank, joining them, and applying a cutting process to the portion including the end A of the blank.

About the obtained drill, the drilling test was done on the following conditions. The results are shown in Table 5.
(Drilling test conditions)
Work material: FR4, 0.8mm thickness, 3-ply drill shape: φ0.25mm
Rotation speed: 160krpm
Feed rate: 3.2 m / min Evaluation item: Number of drilled products (pieces) and drill flank wear width after testing (μm)

From Tables 1 to 5, it can be seen from Sample No. 1 that Co _A is the same as Co _B. In I-14, the flank wear width was large. In I-15, initial chipping occurred in the first hole due to insufficient sintering. The average mean KAM value of the center portion A1 (A) is the same as the average KAM value of the center portion B1 (B), the average particle size _{a A} of WC particles in the central portion A1 is, the WC grains in the central portion B1 Sample No. which is the same as the particle size a _B In I-16 to I-22, the chipping resistance was low, the hole position accuracy was lowered, and the number of workpieces was reduced. Sample No. In I-16 to I-22, 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, so the flank wear width is large and the number of processed parts is also large. There were few things.

On the other hand, sample No. No. Co _A is smaller than Co _B , and the average KAM value in the central part A1 is smaller than the average KAM value in the central part B1. In I-1 to I-13 and I-23, the flank wear width was small and the number of workpieces increased. Among them, sample No. 1 having an average KAM value in the central portion A1 of 0.50 to 0.65 ° and an average KAM value in the central portion B1 of 0.75 to 0.92 °. In I-1, I-2 and I-7 to I-13, the number of processed parts further increased.

Specimen No. in which the average KAM value (AO) of the WC particles in the outer peripheral part A2 is smaller than the average KAM value of the WC particles in the central part A1. In I-1 to I-3 and I-7 to I-13, the number of processed parts was large.

In addition, the sample No. having a ratio (Co _A / Co _B ) of 0.2 to 0.7 was used. In I-1, I-2, I-7, I-8, and I-10 to I-13, the number of processed parts increased. Further, the average particle diameter of _{a A} at the center portion A1 is greater than the average particle size _{a B} at the central portion B1 Sample No. In I-1 to I-4, I-6 to I-13, and I-23, the flank wear width was small and the number of workpieces was large. All samples, an average particle diameter of _{a A} is 0.3 ~ 1.5 [mu] m, an average particle diameter of _{a B} was 0.1 ~ 0.9 .mu.m. In particular, sample Nos. 1 and 4 in which the ratio (a _A / a _B ) of the average particle size a _A to the average particle size a _B is 1.5 to 4. In I-1 to I-3 and I-7 to I-13, the number of processed parts increased.

Further, sample Nos. 1 and 2 in which the average particle size a _AO , the average particle size a _A, and the ratio (a _AO / a _A ) are 1.1 to 2. In I-1 to I-4, I-7, I-9, and I-11 to I-13, the flank wear width was smaller and the number of workpieces increased.

Furthermore, sample no. _Each of 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 , the flank wear width is small, and the number of processed _parts is large. It was. In particular, Sample No. No. ₂ having a gradient S _1Co of 0.2 to 1% by mass / mm and a gradient S _2Co of 0 to 0.2% by mass / mm. In I-1, I-2, and I-6 to I-12, the flank wear width was small.

Using the raw material powder used in Example 1, the compacts shown in Table 6 were produced and fired under the conditions shown in Table 7. And the drill was produced using this blank. About the obtained drill, the drilling test was done on the following conditions. The results are shown in Tables 7-10.
(Drilling test conditions)
Work material: FR4 material, 24-layer plate, 3.2 mm thickness, single drill shape: φ0.25 mm
Rotation speed: 160krpm
Feed rate: 3.2 m / min Evaluation item: Number of drilled products (pieces) and drill flank wear width after testing (μm)

According to Tables 6 to 10, the sample No. No. Co _A is smaller than Co _{B and} the average KAM value in the central portion A1 is smaller than the average KAM value in the central portion B1. In II-1 to II-4, the flank wear width was small and the number of workpieces increased. Sample No. In II-1 to II-4, the average particle diameter a _A in the central part A1 was larger than the average particle diameter a _B in the central part B1.

Using the raw material powder used in Example 1, the compacts shown in Table 11 were produced and fired under the conditions shown in Table 12. And the drill was produced using this blank. About the obtained drill, the drilling test was done on the following conditions. The results are shown in Tables 12-15.
(Drilling test conditions)
Work material: FP4 material, 0.06mm thickness, 10-ply drill shape: φ0.105mm
Rotation speed: 300krpm
Feeding speed: 1.8 m / min Evaluation item: Number of products that have been drilled (pieces) and flank wear width of the drill after the test (μm)

From Tables 11 to 15, the sample No. No. Co _A is smaller than Co _{B and} the average KAM value in the central part A1 is smaller than the average KAM value in the central part B1. In III-1 to III-3, the flank wear width was small and the number of workpieces increased. Sample No. In III-1 to III-3, the average particle size a _A in the central portion A1 was larger than the average particle size a _B in the central portion B1.

1 Drill (cutting tool)
2 Blank (blank for cutting tool)
3 Shank 5 Cutting edge 6 Groove 7 Neck 8 Body 11 First region 12 Second region 13 Third region 14 Fourth region 15 Projection

Claims

It is made of a cemented carbide containing WC particles and Co, and is a long rod-shaped body having a first end and a second end in the longitudinal direction,
The first end portion has a first center portion located at the center in the width direction,
The second end portion has a second central portion located at the center in the width direction,
The Co content in the first central portion is less than the Co content in the second central portion,
In measurement of an average KAM value measured by an electron beam backscatter diffraction (EBSD) method using a scanning electron microscope with a backscattered electron diffraction image system of the WC particle, the average KAM value in the first central portion is the first KAM value. 2 Rod-shaped body smaller than the average KAM value at the center.
The first end portion further includes a first outer peripheral portion located on the outer periphery,
The rod-shaped body according to claim 1, wherein the average KAM value in the first outer peripheral portion is smaller than the average KAM value of the WC particles in the first central portion.
3. The rod-like shape according to claim 1, wherein the average KAM value in the first central portion is 0.50 to 0.65 °, and the average KAM value in the second central portion is 0.75 to 0.92 °. body.
The rod-shaped body according to any one of claims 1 to 3, wherein an average particle diameter of the WC particles in the first central portion is larger than an average particle diameter of the WC particles in the second central portion.
The rod-shaped body according to claim 4, wherein a ratio of an average particle diameter of the WC particles in the second center part to an average particle diameter of the WC particles in the first center part is 1.5 to 4.
The rod-shaped body according to claim 4 or 5, wherein an 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 central portion to an average particle diameter of the WC particles in the first outer peripheral portion is 1.1 to 2.
5. The average particle diameter of the WC particles in the first central portion is 0.3 to 1.5 μm, and the average particle diameter of the WC particles in the second central portion is 0.1 to 0.9 μm. The rod-shaped body in any one of thru | or 7.
The rod-shaped body according to any one of claims 1 to 8, wherein a ratio of a Co content in the second central portion to a Co content in the first central portion is 0.2 to 0.7.
The rod-shaped body is located on the second end side, the second region where the Co content is changed by the slope S2Co , and the Co-like body is located on the first end side. And a first region in which the content of S varies with the gradient S 1Co ,
The inclined S 1co is, the rod-like body according to any one of the inclined S greater claim than 2Co 1 to 9.
The rod-shaped body according to claim 10, wherein the inclined S 1Co is 0.2 to 1% by mass / mm, and the inclined S 2Co is less than 0.2% by mass / mm.
A long cutting tool comprising a cemented carbide containing WC particles and Co, and having an end X having a cutting edge and an end Y located on the shank side in the longitudinal direction,
The end X has a center X1 located at the center in the width direction,
The end portion Y has a central portion Y1 located at the center in the width direction,
The content of Co in the central portion X1 is less than the content of Co in the central portion Y1,
In the measurement of the average KAM value measured by an electron beam backscatter diffraction (EBSD) method using a scanning electron microscope with a backscattered electron diffraction image system of the WC particles, the average KAM value in the X central portion is the Y center. Cutting tool smaller than the average KAM value in the part.