JP4744486B2 - Throw-away tip and method for manufacturing throw-away tip - Google Patents

Description

  The present invention relates to a throw-away tip whose surface is coated with a coating layer, and in particular, to a throw-away tip in which a cutting blade is honed.

Conventionally, as a cutting edge shape of a throw-away tip, chamfer honing or R honing processing is performed on the tip of the cutting edge in order to increase the cutting edge strength. Further, after the honing process described above, in order to increase the wear resistance of the throwaway tip, at least the cutting blade surface of the cemented carbide or cermet base material is coated with a coating layer by a vapor phase synthesis method such as a CVD method or a PVD method. Is formed (for example, refer to Patent Document 1).
Japanese Utility Model Publication No. 5-16006

  However, in the throw-away tip that has been subjected to the conventional honing process and coated with the coating layer, although the cutting edge strength is improved, the adhesion strength of the coating layer is insufficient. In such processing, the coating layer peels off at the end portion of the honing and microchipping occurs, which limits the life of the chip.

  The present invention has been made to solve the above-described problems, and an object thereof is to provide a throw-away tip that can remarkably improve the chipping resistance of a cutting blade.

  As a result of studying the above problems, the present inventors have been able to increase the adhesion strength of the coating layer in the honing termination region of the cutting edge by improving the honing treatment method before forming the coating layer. It has been found that the chipping resistance of the throw-away tip can be improved by effectively suppressing the minute chipping generated on the blade.

That is, the throw-away tip of the present invention has a base material having a cutting edge formed at an intersecting ridge portion with a main surface forming a rake face and a side surface forming a flank surface, and having a substantially flat plate shape, and the surface of the base material and coated coating layer, a throw-away tip having a by a, and provided with a honing portion across the flank from the rake face of said cutting edge, from the beginning the rake face from the honing end of the flank In the width region up to 1 mm in height, the arithmetic mean roughness (Ra) of the interface between the honing portion and the coating layer is 0.1 to 0.5 μm, and the coating layer adheres in the width region The strength is higher than the adhesion strength of the coating layer at the central portion of the flank.

  Further, the honing preferably has a honing width a on the rake face side of 0.01 to 0.2 mm and a honing width b on the flank face side of 0.005 to 0.08 mm.

  According to the throw-away tip of the present invention, the coating in the lower end region of the honing starting from the honing end portion of the cutting edge and extending in the direction away from the rake face by improving the honing treatment method before forming the coating layer, etc. As a result of increasing the adhesion strength of the layer, it is possible to effectively suppress minute chipping generated on the cutting edge and improve chipping resistance of the throw-away tip.

  Further, according to the throwaway tip manufacturing method of the present invention, by increasing the adhesion strength of the coating layer in the honing lower end region starting from the honing end portion of the cutting edge and extending in the direction away from the rake face, It is possible to manufacture a throw-away tip with suppressed peeling of the coating layer and thereby improved chipping resistance.

  The throw-away tip (hereinafter simply referred to as a tip) of the present invention will be described with reference to FIG.

  According to FIG. 1, the chip 1 has a cutting edge 5 formed at a crossing ridge portion between a main surface forming the rake face 3 and a side surface forming the flank 4 of the base material 2 having a substantially flat main surface. The surface of the base material 2 is covered with a coating layer 6, and a honing portion 8 is provided from the rake face 3 to the flank face 4 of the cutting edge 5.

  According to the present invention, the adhesion strength of the coating layer 6 in the honing lower end region (hereinafter, simply referred to as region A) extending in the direction away from the rake surface 3 from the honing end of the flank 3 is the center of the flank 4. It is a great feature that it is higher than the adhesion strength in the part B, and this makes it possible to use the region A, especially in the vicinity of the end of the honing part 8 that becomes a cutting edge ridge line that is particularly susceptible to minute chipping due to peeling of the coating layer 6 during cutting. Since the adhesion of the coating layer 6 can be improved and the peeling of the coating layer 6 can be prevented, the chipping resistance and wear resistance of the cutting edge can be remarkably improved, and the life of the chip 1 can be extended.

  The adhesion strength in the present invention refers to the adhesion strength of the coating layer 6 measured by a so-called scratch test in which the surface of the coating layer 6 is rubbed with a load cell and the strength at which the coating layer 6 is peeled off is measured.

  Here, the improvement of the adhesion strength of the coating layer 6 is effective by performing in the vicinity of the end of the honing portion 8 that is the cutting edge ridge line, but in the region A, the position of the end opposite to the honing end is If the height H from the rake face 3 is up to 1 mm, it is more preferable because it is possible to suppress costs and honing time.

  Further, according to the present invention, the honing portion 8 may be only R honing, but it is desirable that the honing portion 8 is chamfer honing as shown in FIG.

  Further, the arithmetic average roughness (Ra) of the interface between the honing portion 8 and the coating layer 6 in the region A is 1 μm or less, particularly 0.1 to 0. 0 in order to increase the adhesion strength of the coating layer 6 in the region A. 5 μm is desirable. In addition, the said unevenness | corrugation points out the maximum value of the unevenness | corrugation difference in the said interface in the cross-sectional SEM photograph of the arbitrary parts including the interface of the honing part 8 and the coating layer 6. FIG. In addition, it is desirable that the surface roughness of the central portion of the flank 4 is 0.5 to 2 [mu] m, particularly 0.6 to 1.5 [mu] m in terms of arithmetic average roughness (Ra).

  Furthermore, in order to prevent peeling of the coating layer 6 and to suppress the wear resistance of the chip 1, the total film thickness of the coating layer 6 at the center portion of the flank is 0.2 to 20 μm, particularly 1 to 15 μm. Is desirable.

  On the other hand, in the present invention, the base material 2 can be any of cemented carbide, cermet, or ceramic, but is most suitably applicable to cemented carbide in terms of adhesion strength with the coating layer 6. is there.

On the other hand, for the coating layer 6, TiC, TiCN, TiN, (TiM) N (wherein M is at least one selected from the group of Al, Si, Zr and Cr) formed by CVD or PVD, Al _At least one layer selected from the group consisting of ₂ O ₃ , diamond (including PCD and DLC) and cBN or a multilayer of these can be applied, but the coating layer formed by the CVD method is the most preferable in terms of adhesion strength. It is valid.

  Next, a method for manufacturing the above-described chip 1 of the present invention will be described.

  First, a substantially flat base material 2 is prepared, and R honing is performed on the portion of the base material 2 forming the cutting edge 5.

  Here, in order to perform R honing, as shown in FIG. 2 (a), first, the rake face 3 of the base material 2 is arranged as a machining surface, and the flank 4 side of the base material 2 is fixed to the fixing jig. 11 to fix. At this time, according to the present invention, the protruding amount h for protruding the base material 2 from the fixed jig is not only directly under the conventional cutting blade, but also 1.1 mm or more from the rake face to a height of about 1/3 of the chip flank face. It is important to make the protrusion protrude, and by controlling this and the following honing conditions, the adhesion strength of the coating layer in the region A can be increased. As a result, the chip resistance of the chip can be improved.

As a method of performing R honing, a grinding stone 12 of grade G200 or higher in which abrasive grains are dispersed in a rubber member is placed on the rake face side of the chip, and a pressure of ² to 4 kg / cm ² is applied. By rotating the grindstone for 10 seconds, the cutting edge 5 can be cut into an R shape, and at the same time, the flank portion immediately below the cutting edge 5 can be processed so as to be boiled without being cut. As a result, the portion processed to be boiled is slightly polished to improve the surface roughness to the extent that the adhesion of the coating is improved, and the fresh surface of the base material is exposed. The adhesion force of the portion in the coated layer can be improved, and the adhesion strength of the coating layer and the chip resistance of the chip in the region A can be improved.

  Here, the amount of polishing by R honing is, for example, a = 0.01 to 0.2 mm on the rake face side and flank face side in order to achieve both wear resistance and fracture resistance of the cutting edge 5. It is desirable that b = 0.005 to 0.08 mm. That is, when the polishing amount of R honing exceeds the above range, the region A is excessively polished and the adhesion of the coating layer is reduced.

  Next, in order to enhance the sharpness of the cutting blade 5, if desired, the R honing portion is further subjected to chamfer honing. As shown in FIG. 2 (b), first, the cutting blade 5 for honing is protruded in a state in which the chip 1 is arranged at a specific angle θ by the fixing jig 15, and the cutting blade 5 is rotated on the grindstone 16 that rotates. Apply and polish. The polishing amount of the cutting blade 5 may be controlled while observing the polishing state of the cutting blade 5 with a microscope.

  The amount of polishing by chamfer honing is, for example, a = 0.05 to 0.2 mm on the rake face side and b = 0.02 to 0 on the flank face side in order to achieve both the sharpness of the cutting edge 5 and the prevention of chipping. .1 mm and honing angle θ = 15-30 ° are desirable.

  Then, a coating layer is deposited on the chip subjected to the chamfer honing by a vapor phase synthesis method such as a CVD method or a PVD method.

  In addition, in order to improve the wear resistance of the entire coating layer and the fracture resistance by reducing the residual stress, after forming a coating layer as desired, the coating layer of the honed cutting blade 5 portion is applied from the rake face side. It is desirable to grind lightly again in the same way as R honing, so that the thickness of the top layer of the coating is reduced or removed relative to other parts.

[Example]
Example 1 Abrasive grains are dispersed in a rubber member on the rake face side of a chip on the surface of a CNMG-shaped chip base material made of a cemented carbide in which WC particles having an average particle diameter of 1.5 μm are bonded by Co. After placing the grade (TKX) grindstone shown in Table 1 and applying the R honing shown in Table 1 according to the conditions shown in Table 1, the honing is carried out in a state where the chip 1 is arranged at a specific angle. Chamfer honing was performed so that the cutting edge 5 was projected and the cutting edge 5 was applied to the rotating grindstone so that the rake face side a = 0.1 mm, the flank face side b = 0.04 mm, and the honing angle θ = 20 °. . The amount of honing was obtained by observing with a microscope.

Next, a multilayer coating layer of TiCN (8 .mu.m) -Al2 O3 (2.5 .mu.m) -TiN (0.5 .mu.m) is formed on the above-mentioned chip base material by the CVD method, and the coating layer of the cutting edge portion of this coating film A chip was prepared by placing a grindstone in which abrasive grains were dispersed in a rubber member from the rake face side and polishing again by rotating the grindstone for 1 second while applying a pressure of ² kg / cm ² .

About the obtained chip | tip, the adhesion strength in the area | region A from the end of honing and the adhesion strength of the flank center part B were measured about five arbitrary places in the scratch test, and the average value was computed. In addition, the adhesion strength of the flank central portion B was 62 N on average at any five locations in any chip. Further, a cutting test was performed under the following conditions, and the chipping state of the chip cutting edge after cutting for 3 minutes was observed. Further, a cutting test was continuously performed under the same conditions, and the total cutting time until the cutting edge was lost was measured. The results are shown in Table 1. Cutting conditions Cutting speed: 250 m / min Cutting depth: 4 mm Feeding: 0.35 mm / rev Work material: FC250 Cutting condition with 4 grooves: Dry type

  As shown in Table 1, sample No. Sample No. 10 that includes at least one condition that does not contribute to the improvement of the adhesion strength in the region A under the processing conditions in the sample subjected to the R and Honing treatments. In all of Nos. 6 to 9, the adhesion strength of the coating was low, and chipping of the coating layer occurred during cutting.

  On the other hand, among the samples subjected to the R honing treatment, all of the processing conditions were sample Nos. Processed under the conditions that the adhesion strength in the region A was improved. In each of Nos. 1 to 5, the adhesion strength of the coating was improved and the chip life was long.

  As mentioned above, although the cutting test result in the sample which performed the chamfer honing after the R honing process was shown in Example 1, the cutting test in the sample which performed only the R honing process which does not perform a chamfer honing as Example 2 below. Results are shown.

  (Example 2) Sample No. Sample No. 1 except that no chamfa honing is applied to The throw-away tip was prepared in the same manner as in Example 1, and the same items as in Example 1 were evaluated. As a result, the adhesion strength in the region A was 67 N, the cutting edge in the cutting test was in good condition, and the time to breakage was 250 seconds (sec). Met.

  On the other hand, as a comparative example, sample No. Sample no. The throw-away tip was produced in the same manner as in Example 6, and the same items as in Example 1 were evaluated. The time to defect was 80 seconds (sec).

It is a schematic sectional drawing which shows an example of the throw away tip of this invention. It is a conceptual diagram for demonstrating the grinding | polishing process ((a) R honing, (b) chamfer honing) of the throw away tip of this invention.

Explanation of symbols

1 Throw away tip (chip)
2 Base material 3 Rake face (main face)
4 Flank (side)
5 Cutting edge 6 Coating layer 8 Honing part A Honing end area B Flank center H Height from rake face H Projection amount 11, 15 Fixing jig 12, 16 Grinding wheel

Claims (2)

A base material having a substantially flat plate shape and having a cutting edge formed at a crossing ridge portion between a main surface forming a rake face and a side surface forming a flank; and a coating layer coated on the surface of the base material. A throw-away chip,
A honing part is provided from the rake face of the cutting blade to the flank face,
The arithmetic average roughness (Ra) of the interface between the honing portion and the coating layer is 0.1 to 0.5 μm in the width region starting from the honing end of the flank and up to 1 mm from the rake face. And a throw-away tip, wherein the adhesion strength of the coating layer in the width region is higher than the adhesion strength of the coating layer in the central portion of the flank. The honing section, claim honing width a of the rake face side is 0.01 to 0.2 mm, and honing width b of the flank side is characterized by a 0.005～0.08Mm 1 serial mounting of the throw-away tip.

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