JP5424911B2 - Cutting tools - Google Patents

Description

  The present invention relates to a cutting tool, and more particularly to a cutting tool suitable for processing difficult-to-cut materials.

  Cutting tools used for cutting metals and the like have become stricter recently, and the cutting conditions under which cutting tools are used as well as extending the service life are used under severe conditions such as high-speed cutting and difficult-to-cut materials. There is a tendency. In such a cutting tool, as the processing conditions become severe, the cutting edge becomes hot at the time of cutting, and the corner portion including the cutting edge that has become hot is largely damaged due to thermal shock. In particular, when metal titanium (Ti), which is known as a difficult-to-cut material, is processed, chips generated at the cutting edge tip tend to rise rapidly and be discharged, so there is a large local load and heat only at the cutting edge tip. As a result, the tip of the cutting edge becomes hot and the deterioration of the material is likely to progress, and there is a large temperature difference between the corner cutting edge that has become hot and the side cutting edge that does not easily rise. There was a problem that a crack was generated near the cutting edge due to thermal shock, and this progressed and the entire corner portion was lost and damaged greatly.

  Therefore, for example, in Patent Document 1, by forming a recess that prevents chips from coming into contact with the bottom surface of the breaker groove, the contact area of the chips with the breaker groove is reduced, and only the vicinity of the cutting edge becomes hot. It is described that it can prevent and suppress the occurrence and progression of thermal cracks. Further, in Patent Document 2, a coolant supply hole is provided in a clamp member that holds a throw-away tip in a clamp-on manner, and a coolant supply pipe that communicates with the coolant supply hole is provided in the holder so that it is close to the cutting edge. The structure which supplies the refrigerant | coolant which cools a cutting blade from is disclosed.

  Further, Patent Document 3 discloses a configuration in which a protrusion row in which a plurality of protrusions are arranged at a position close to the cutting edge is provided, and the chip is prevented from rising due to solid contact from the cutting edge to the breaker and rising of the temperature of the cutting edge. Has been. Further, in Patent Document 4, in a throw-away tip provided with a cBN sintered body forming a cutting edge in a main body made of cemented carbide or cermet, a chip breaker is provided at a position near the cBN sintered body of the main body, and at least A throw-away tip is disclosed in which a titanium compound-based coating layer is formed on a chip-contact surface of a breaker. Patent Documents 3 and 4 describe a configuration in which a coating layer is formed on the entire surface of the chip.

JP-A-4-294911 JP 2002-346810 A JP 2009-006437 A JP 09-267203 A

  However, as in Patent Document 1, the method of forming a recess so that chips do not come into contact with the bottom surface of the breaker groove is such that chips generated at the tip of the cutting edge rise sharply and are discharged as in the processing of titanium metal (Ti). The form to be used has no effect, and on the contrary, it often leads to a reduction in the strength of the cutting edge tip and the fracture resistance is often lowered. In addition, in the configuration in which the coolant supply mechanism is provided near the cutting edge as in Patent Document 2, since the apparatus becomes complicated and large, it is applicable to a tip having a small cutting edge vicinity such as a grooved tip. In addition, there is a problem that the setting of the clamp member is troublesome and the workability is poor.

Further, in the case where the coating layer is formed on the entire rake face including the surface of the breaker projection as in Patent Documents 3 and 4, when the Ti compound layer or the Al ₂ O ₃ layer is formed, the thermal conductivity of the substrate is higher than that of the substrate. The thermal conductivity of the coating layer was poor, and the tool life could not be extended because the temperature rise of the cutting edge could not be suppressed.

  Accordingly, an object of the present invention is to provide a cutting tool capable of extending the tool life even in cutting of difficult-to-cut materials such as titanium metal.

The cutting tool of the present invention comprises a cemented carbide base, and a group of protrusions in which a plurality of protrusions are arranged at a position close to the cutting edge of the rake face with a cross ridge line between the rake face and the flank face as a cutting edge. In addition, an Al ₂ O ₃ layer is formed only on the protrusions.

  Here, the plurality of protrusions are preferably circular when the rake face is viewed in plan.

Further, a Ti-based cubic layer may be formed as a lower layer of the Al ₂ O ₃ layer.

  Furthermore, it is desirable that the projection is used for grooving including a tip cutting edge and a side cutting edge, and that the four protrusions are arranged in parallel with the tip cutting edge.

Further, another cutting tool of the present invention is made of a cemented carbide base, and a plurality of protrusions are formed at positions near the cutting edge of the rake face with a cross ridge line between the rake face and the flank face as a cutting edge. In addition to providing a group of protrusions arranged side by side, the protrusions are formed by embedding part of Al ₂ O ₃ particles on the surface of the base and protruding partly.

  According to this configuration, since the protrusion is formed of a spherical body separate from the base body, even if the protrusion is dropped during the cutting, the dropped mark becomes a hole and serves as an oil hole. Since it fulfills, the sticking of chips can be suppressed.

According to the present invention, the protrusion is provided in the vicinity of the cutting edge of the substrate made of the cemented carbide and the Al ₂ O ₃ layer is formed only on the protrusion, or the protrusion embedded with the Al ₂ O ₃ particles is formed. Further, the protrusion receives a part of the impact applied to the cutting edge, and the chip does not stick to the solid and the temperature rise of the cutting edge can be suppressed. In addition, since the Al ₂ O ₃ layer has a lower thermal conductivity than the substrate, the Al ₂ O ₃ layer is formed only on the protrusions that come into sharp contact with the chips, and the other parts are cemented carbide with good thermal conductivity. The surface of the cutting tool is constituted by the base. With this configuration, the heat generated by the cutting can be efficiently radiated and the tip of the cutting blade can be prevented from being deteriorated by the heat.

Here, it is desirable that the plurality of protrusions have a circular shape when the rake face is viewed in plan, from the viewpoint of reducing a contact area where chips contact the protrusions. Further, if a Ti-based cubic layer is formed as a lower layer of the Al ₂ O ₃ layer, the wear resistance of the entire coating layer is further improved.

  Furthermore, even in the case of using as a grooving process, that is, as a cutting tool having a cutting form in which it is difficult to feed the cutting fluid or refrigerant to the vicinity of the cutting edge, the effect of the present invention is effectively lost without loss. At this time, the shape of the cutting tool for grooving is a configuration in which four protrusions are arranged in parallel with the tip cutting edge, in order to balance the durability of the protrusion and the prevention of temperature rise of the cutting edge. desirable.

In the case where the protrusion has a structure in which a part of Al ₂ O ₃ particles is embedded on the surface of the base 11 and a part of the protrusion protrudes, the protrusion is formed of a spherical body separate from the base. Therefore, even if the projections fall off during cutting, the traces that fall off become holes and serve as oil holes, so that the sticking of chips can be suppressed.

It is a schematic perspective view about the suitable example of the throw-away tip for grooving. 2A is a schematic view of the chip as viewed from above, and FIG. 2B is a schematic view of the chip as viewed from the tip. They are AA sectional drawing (A), BB sectional drawing (B), and CC sectional drawing (C) of Fig.2 (a). It is AA sectional drawing (A), BB sectional drawing (B), and CC sectional drawing (C) of FIG. 2 (a) about the other embodiment of the throwaway tip for grooving.

  FIG. 1 is a schematic perspective view of an example of a throw-away tip for grooving that is a preferred example of the cutting tool of the present invention, (a) a schematic view of the tip of FIG. 1 as viewed from above, and (b) a tip. FIG. 2, which is a schematic view seen from the direction, (A) AA sectional view, (B) BB sectional view, (C) CC sectional view of FIG. explain.

As shown in FIG. 1, a grooving throw-away tip (hereinafter simply referred to as a tip) 1 cuts a cross ridge line between a rake face 3 and a flank 7 provided on an upper surface of an end portion of a tip body 2. A group of projections in which a plurality of projections 13 are arranged at positions close to the tip cutting edge 4 of the rake face 3 as blades (tip cutting edges 4 and side cutting edges 5 provided on the leading edge and both end edges of the rake face 3 respectively). And an Al ₂ O ₃ layer 10 a is formed only on the protrusion 13.

  Note that the base body 11 forming the chip body 2 is made of a cemented carbide. In addition, it is desirable that the distance between the tip cutting edge 4 and the tip of the protrusion 13 is in the range of 0.1 to 0.7 mm in order for the protrusion 13 to exhibit the effect as a breaker. Furthermore, the size of the protrusion 13 varies depending on the shape of the cutting edge and the cutting conditions. For example, in the case of a throw-away tip for grooving with a blade width of 3 mm, the width of the protrusion 13 is 0.2 to 0.6 mm and the height is Forming with a size of 0.1 to 0.3 mm is desirable for the protrusion 13 to exhibit the effect as a breaker.

Here, according to FIGS. 1 and 2, the plurality of protrusions 13 are circular when the rake face 3 is viewed in plan, and with this shape, the contact area where chips come into contact with the protrusions can be reduced. Further, if the Ti-based cubic layer 10b is formed as the lower layer of the Al ₂ O ₃ layer 10a, the wear resistance of the entire coating layer 10 is further improved. The thickness of the Al ₂ O ₃ layer 10a is 0.5 to 3 μm and the thickness of the Ti-based cubic layer 10b is 0.5 to 3 μm in order to improve the wear resistance without chipping of the coating layer 10. Is desirable.

  Further, the throw-away tip shown in FIGS. 1 to 3 is effective without losing the effect of the present invention even when it is used as a cutting tool in grooving, that is, in a cutting form in which it is difficult to feed cutting fluid or refrigerant to the vicinity of the cutting edge. To work. At this time, as shown in FIGS. 1 to 3, the shape of the cutting tool for grooving is a structure in which four protrusions 13 are arranged in parallel to the front end cutting edge 4, and the durability of the protrusion 13 and the tip cutting end are determined. This is desirable in terms of balancing the prevention of temperature rise of the blade 4.

Note that the structure of the protrusions in the present invention is not limited to the structure shown in FIG. 3, but a part of Al ₂ O ₃ particles embedded in the surface of the substrate 11 as shown in FIG. The protrusion 14 may be configured to protrude. In this case, since the protrusion 14 is formed of a spherical body separate from the base body 11, even if the protrusion 14 is dropped during cutting, the dropped mark becomes a hole and functions as an oil hole. Therefore, it is desirable in that the sticking of chips can be suppressed and the flow of the chips can be smoothed to suppress the temperature rise of the tip cutting edge 4.

  Further, as shown in FIG. 2, the tip cutting edge 4 has a concave shape so as to become lower from the corners on both sides toward the center side, so that the flow of chips is fixed to the center and stabilized. It is desirable in that chips can be processed.

(Production method)
An example of a method for manufacturing the grooving throw-away tip shown in FIGS. First, raw materials are mixed and mixed, a compact is produced by press molding, and grinding is performed after firing to produce a cemented carbide substrate. Then, it can be prepared by forming a coating layer containing Al ₂ O ₃ layer only on the projection by any of the following methods.
Method 1
A method of coating the surface of the substrate other than the protrusions with masking.
Method 2
A method in which the entire surface of a cutting tool is coated, and then the protrusions are covered with masking and polished. Method 3
The surface of the substrate other than the protrusions is coated with a substance containing an alkali metal component, the entire surface of the chip is coated with an Al ₂ O ₃ layer, and then a polishing process such as brushing or blasting is performed to remove the parts other than the protrusions. A method of removing the Al ₂ O ₃ layer.

As a method for forming the coating layer 10 of the Al ₂ O ₃ layer 10a and the Ti-based cubic layer 10b on the base 11, a physical vapor deposition (PVD) method such as a chemical vapor deposition (CVD) method or an ion plating method is used. It can be suitably applied.

In addition, an example of a method for manufacturing a grooving throw-away tip according to another embodiment described in FIGS. First, raw materials are prepared and mixed. Then, after a molded body by press molding for the molded body, Al ₂ O ₃ or embed spherical Al ₂ O ₃ particles such as beads in a predetermined position, or spherical when forming Al ₂ O By press molding in a state where the _three particles are arranged at a predetermined position, a molded body in which Al ₂ O ₃ particles are embedded at the predetermined position is obtained. By firing this molded body and then grinding it as desired, a throw-away tip embedded with Al ₂ O ₃ particles can be produced.

WC powder, Co powder, Cr ₃ C ₂ powder and VC powder were mixed, and paraffin was added as a binder and granulated to prepare a granulated powder having an average particle size of 100 μm. Next, the throw-away tip for grooving shown in FIG. 1 (tip thickness (the height of the molded body) t ₁ = 4.3 mm, blade width = 3.0 mm, tip cutting edge clearance angle β ₁ = 4.5 Side, cutting edge clearance angle β ₂ = 6 °, rake angle α ₁ = 6.0 ° at the corner of the tip edge, and rake angle α ₂ = 14.5 ° at the center of the edge edge) A compact was obtained by press molding using a mold. The molded body was treated to remove the binder and vacuum fired to perform grinding and honing, and then a throw-away tip having the protrusions shown in Table 1 formed through the steps shown in Table 1 (Sample Nos. 1 to 1). 8). In addition, about the sample whose diameter of a processus is 0.5 mm or less, it is set as the form which arranged 4 processus | protrusions in parallel with respect to the front-end | tip cutting edge like FIGS. 1-3, and about the sample whose process diameter exceeds 0.5 mm Two protrusions were arranged in parallel with the tip cutting edge.

Next, the cutting test was done on the following cutting conditions using the obtained cermet cutting tool. The results are shown in Table 1.
Work material: Ti-6Al-4V
Cutting speed: 60 m / min Feed: 0.1 mm / rev
Depth of cut: 1.5 mm single cut Cutting state: wet (uses water-soluble cutting fluid)
Evaluation method: Time until chipping (until continuous machining is impossible) (cutting up to 85 minutes)

  From Table 1, sample no. In No. 8, damage occurred such that the entire corner R was lost after a cutting time of 5 minutes. In addition, Sample No. with a coating layer formed on the entire surface of the chip. In No. 7, the heat dissipation was reduced and sudden loss occurred after 7 minutes of cutting.

  On the other hand, sample no. In all of Nos. 1 to 6, sudden chipping hardly occurred and the tool life was prolonged.

1 Throw-away insert for grooving
2 Chip body 3 Rake face 4 Tip cutting edge 5 Side cutting edge 7 Flank face 7a Front relief face 7b Side relief face 8 Seating face 10 Covering layer 10a Al ₂ O ₃ layer 10b Ti-based cubic layer 11 Base 13, 14 Protrusion

Claims (5)

It is made of a cemented carbide substrate, and a projection group in which a plurality of projections are arranged at a position near the cutting edge of the rake face with a crossing ridge line between the rake face and the flank as a cutting edge, and only the projection is provided. A cutting tool in which an Al ₂ O ₃ layer is formed.   The cutting tool according to claim 1, wherein the plurality of protrusions are circular when the rake face is viewed in plan. The cutting tool according to claim 1, wherein a Ti-based cubic layer is formed as a lower layer of the Al ₂ O ₃ layer.   The cutting tool according to any one of claims 1 to 3, wherein the cutting tool is used for grooving including a tip cutting edge and a side cutting edge, and has four protrusions arranged in parallel to the tip cutting edge. The substrate is made of a cemented carbide substrate, and a projection group in which a plurality of projections are arranged at a position near the cutting edge of the rake face with a cross ridge line between the rake face and the flank face as a cutting edge, A cutting tool in which a part of Al ₂ O ₃ particles is embedded in the surface of the base 11 and a part of the cutting tool protrudes.

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