JP2007307667A - Tool for bore machining - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a tool for throw-away type bore machining which performs bore machining so as to provide excellent finished surface quality without lowering rigidity of an insert and with hardly generating chattering vibration. <P>SOLUTION: The tool is provided with a small diameter rod-shaped part having a cutting edge at a distal end part and a substantially square columnar shank part integrally continuous to the rod-shaped part, and has a tip pocket part on a rake face of the cutting edge. When a longitudinal direction dimension from the distal end of the cutting edge to the tip pocket part is taken as A and a longitudinal direction dimension of the small diameter rod-shaped part is taken as L, 0.050≤A/L≤0.300 is satisfied. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an inner diameter machining tool, for example, a machining tool suitable for inner diameter machining of a small-diameter part such as a drive motor component for a disk-shaped storage medium, an electric / electronic component, and an automobile component.

  In the inner diameter spreading processing and copying processing, there is a problem that the tool diameter becomes smaller as the processing diameter becomes smaller, and vibration such as chatter is likely to occur due to a decrease in tool rigidity. Further, the repeatability of the cutting edge is required due to the reduced diameter and higher accuracy of the processed parts. In order to cope with such problems, Patent Documents 1 to 3 disclose throw-away type inner diameter machining tools in which a throw-away insert (hereinafter simply referred to as an insert) is attached to the tip of a holder.

Japanese Patent No. 3330085 Japanese Patent No. 3389497 JP 2005-138200 A

Japanese Patent Laid-Open No. 2004-228561 enables strong clamping by supporting the insert with a set bolt while supporting it at the four points, but the shortest part of the insert is located in the lateral direction at the end of the pair of insert restraint surfaces that intersect at an acute angle. By pressing with a set bolt, the rotational force is applied to the insert, and the straightness of the small-diameter bar is impaired. Patent document 2 is an insert which inserts and processes only a small-diameter bar-shaped part provided with a cutting edge into an inner diameter of a workpiece to be processed, and chips are removed by a laterally curved part of a rake face and a concave notch continuous to the laterally curved part. Disclosed is an inner diameter machining tool insert that is guided to the side clearance surface and is excellent in chip dischargeability. However, the concave notch at the tip of the small-diameter bar-shaped part that protrudes for inner-diameter machining is a breakage of the small-diameter bar-shaped part. Due to the decrease in rigidity due to the decrease in area, chattering may occur and the finished surface quality may be degraded. Since Patent Document 3 also prioritizes the chip discharging property, it is difficult to say that consideration of the cross-sectional area regarding the rigidity of the insert is sufficient.
SUMMARY OF THE INVENTION Accordingly, the present invention is to provide an inner diameter machining tool that does not reduce the rigidity of an insert, hardly generates chatter vibration, and can perform inner diameter machining with excellent finished surface quality.

  The present invention is an inner diameter machining tool having a small-diameter rod-shaped portion having a cutting edge at a tip portion and a substantially prismatic shank portion integrally connected to the small-diameter rod-shaped portion, and having a chip pocket portion on a rake face of the cutting blade. When the longitudinal dimension from the tip of the cutting edge to the tip pocket portion is A and the longitudinal dimension of the small-diameter rod-shaped portion is L, 0.050 ≦ A / L ≦ 0.300. This is an inner diameter machining tool. By adopting this configuration, it is possible to provide an inner diameter machining tool that does not reduce the rigidity of the insert, hardly generates chatter vibration, and can perform inner diameter machining with excellent finished surface quality.

  In the inner diameter machining tool of the present invention, it is possible to have two or more cutting edges on the outer periphery of the tip of the small-diameter bar-shaped portion. With this configuration, a plurality of cutting edges can be selected and used by an index, and the substantial tool life can be extended by multiplying the number of cutting edges. In the inner diameter processing tool of the present invention, the cross-sectional shape of the small-diameter bar-like portion excluding the chip pocket portion may be any of a substantially circular shape and a substantially polygonal shape. In the case of a substantially circular shape, it is possible to approximate the machining inner diameter shape, and even an insert for machining a small inner diameter can be manufactured without reducing the cross-sectional area more than necessary. The shape can be configured with a straight surface, and an insert that is inexpensive in terms of grinding can be manufactured.

  The present invention can provide an inner diameter machining tool that does not reduce the rigidity of the insert, hardly generates chatter vibration, and can perform inner diameter machining with excellent finished surface quality.

The present invention will be described in detail with reference to the drawings. FIG. 1 is a front view of an inner diameter machining tool according to the present invention, and FIG. 2 is a view of the relationship between the tool and the inner diameter of the inner diameter when viewed from the Z direction of FIG.
The inner diameter machining tool of the present invention includes a small-diameter bar-shaped portion 2 having a cutting edge 1 at a tip portion and a substantially prismatic shank portion 3 integrally connected to the small-diameter rod-shaped portion 2, and a rake face of the cutting edge 1 at the tip portion. This is an inner diameter machining tool having an upper chip pocket portion 4. Here, the chip pocket portion 4 is a kerf portion that passes when chips are discharged. If the chips become powdery, they stay here temporarily. Further, when the diameter of the cross-section of the small-diameter bar-shaped portion 2 or the diameter of the circumscribed circle is d (mm) and the diameter of the circumscribed circle of the cross-section of the shank portion 3 is D (mm), d ≦ D, d ≦ 6 It may be a relationship. The shank portion 3 is a portion for clamping and is usually formed in a substantially prismatic shape, but the shape may be a substantially cylindrical shape. In the case of a substantially prismatic shape, the prism portion is clamped and fixed, so that the clamping surface comes into contact with the surface and a strong clamping force is obtained. In the case of a substantially cylindrical shape, a known collet fixing or bolt fixing using a sleeve may be used, so that it can be set in a processing facility that uses a rotary tool such as a drill attached concentrically with the processing work rotation center. Further, in the present invention, when the longitudinal dimension from the tip of the cutting edge to the tip pocket portion 4 is A and the longitudinal dimension of the small-diameter bar-like portion 2 is L, the condition of 0.050 ≦ A / L ≦ 0.300 is satisfied. Satisfied. When the A / L value is within this range, the rigidity of the small-diameter rod-shaped portion 2 is not lowered, chatter vibration is hardly generated, and inner diameter machining with excellent finished surface quality is possible. When the A / L value is less than the limit value, the rigidity of the tool is maintained and the finished surface is not deteriorated by chatter, but the chips are not discharged well, and the finished surface is damaged by the chips. According to the present invention, the rigidity of the tool can be maintained, and the chip discharge performance can be improved and a good finished surface can be obtained. On the other hand, if it exceeds the upper limit value, the chip discharging property for discharging chips to the outside of the machining diameter is improved, but on the other hand, the rigidity of the small-diameter bar-shaped portion 2 is reduced, and vibration such as chatter occurs. However, the roughness of the processed surface is remarkable, which is not preferable. In precision machining, machining conditions such as a cutting depth of 0.1 mm or less and a feed rate of 0.05 mm / rotation or less are used, and the generated chips are mainly in the form of continuous curls or powders, and the chips are in the chip pocket section. 4 is discharged out of the machining diameter. When the chips become powdery, a part of the generated chips is temporarily accumulated in the chip pocket portion 4, and after the processing is completed, the insert 5 comes out of the processing diameter and is discharged. In internal diameter machining, it is important not to damage the work surface with chips, and for that purpose it is necessary to induce a flow of chips that does not damage the work surface. The present invention achieves this. Further, the present invention is preferably used under precision machining conditions such as a cutting depth of 0.1 mm or less and a feeding amount of 0.05 mm / rotation or less. It is desirable to be applied to ultra-precise machining condition areas such as an amount of 0.01 mm / rotation or less.

In this invention, it can have two or more cutting edges on the outer periphery of the front-end | tip part of this small diameter rod-shaped part. In FIG. 2, cutting edges are provided at two locations. With this configuration, a plurality of cutting edges can be selected and used by an index, and the substantial tool life can be extended by multiplying the number of cutting edges. Further, the inner diameter machining tool of the present invention may be provided with a small-diameter rod-like portion at both ends of the shank portion 3 and a plurality of cutting edges at both ends. As a result, the number of cutting edges is doubled and the actual tool life can be doubled.
In the inner diameter machining tool of the present invention, the cross-sectional shape of the small-diameter rod-like portion 2 excluding the tip pocket portion 4 may be any of a substantially circular shape and a substantially polygonal shape. It is possible to approximate the machining inner diameter shape, and even inserts for machining the smallest inner diameter can be manufactured without reducing the cross-sectional area more than necessary. An insert that can be configured with a surface and is inexpensive in terms of grinding can be manufactured. By not reducing the cross-sectional area more than necessary, the rigidity of the small-diameter bar-like portion 2 can be maintained and vibrations such as chatter can be suppressed.

In order to ensure that the cutting edge bites into the workpiece under the low cutting and low feed conditions in the precision finishing process to which the inner diameter machining tool of the present invention is applied, the ridgeline of the cutting edge 1 is processed into a sharp edge. It is preferable to do. In order to process the ridgeline of the cutting edge 1 into a sharp edge, the insert base is made of a WC-based cemented carbide consisting of 6 to 12% by weight of Co and an average particle diameter of WC of hard dispersed phase of 0.8 μm or less. That's fine. As a result, sharp edges can be machined and sufficient machining performance can be realized. In order to prevent chipping of the cutting edge 1, a similar substrate can be used even when a cutting edge treatment other than a sharp edge is performed.
In this invention, it is desirable to coat | cover the small diameter rod-shaped part 2 which has at least the cutting edge 1 of the tool for internal diameter processing. By applying the coating, the wear resistance of the cutting edge 1 is improved and the tool life can be extended. When the coating has at least one composition selected from Ti, Al, Cr, Si, and B as the metal component and at least one composition selected from C, N, and O as the nonmetallic component, it is an abrasion resistant coating. A longer life can be achieved. The inner diameter machining tool of the present invention is suitable for applications such as drive motor parts for disk-shaped storage media, electrical and electronic parts, and automobile parts.

When the longitudinal dimension of the chip pocket part is A and the longitudinal dimension of the small-diameter bar-like part is L, the relationship between A and L is important for maintaining the rigidity of the small-diameter bar-like part and obtaining a good finished surface. Therefore, the diameter of the cutting edge centered on the longitudinal axis of the small-diameter bar-shaped part is 3.6 mm, the outer diameter of the small-diameter bar-shaped part excluding the chip pocket part is 3 mm, and the longitudinal dimension of the small-diameter bar-shaped part is 10 mm, 12 mm, 15 mm. Three types of insert base materials were prepared, and an insert having a longitudinal dimension L of the chip pocket portion in a range of 0.48 to 4.6 mm was created. In addition, a WC-based cemented carbide having a WC average particle diameter of 0.8 μm in a hard dispersed phase of 8% by weight and Co of 8% was used for the substrate. What prepared the small diameter rod-shaped part of the tool which coat | covered the (TiAl) N film | membrane was also prepared. Using the above insert, a cutting test was performed under the following cutting conditions.
(Cutting conditions)
Material of work material: SUS430
Processing inner diameter: Diameter 4.0mm
Processing depth: Small-diameter bar-shaped part dimension L-1mm
Cutting speed: 80 m / min
Feeding speed: 0.02mm / rotation Cutting depth: 0.05mm
Cutting fluid: use In the evaluation, the presence or absence of chatter vibration was determined by the presence or absence of chatter on the finished surface, focusing on the finished surface properties. Moreover, the smooth discharge | emission property of the chip was determined by confirming the presence or absence of the damage of the finishing surface by a chip. The evaluation results were classified as follows. In other words, the evaluation was good when the finished surface was good, Δ when the finished surface was damaged by chips, and x when the finished surface had chatter. Table 1 shows the shape and evaluation result of each type of insert.

From the results shown in Table 1, since the inventive examples 1 to 15 had the A / L value within the specified range of the present invention, the rigidity of the tool was maintained and the finished surface was not deteriorated due to chatter vibration. In addition, it was possible to induce a chip flow that did not damage the machined surface, and the finished surface was not damaged by the chip, and good results were obtained. However, in Comparative Examples 16, 18, and 20, since the A / L value was less than 0.050, the rigidity of the tool was maintained and the finished surface was not deteriorated by chatter, but the chips were not discharged well and the cutting was not performed. Damage to the finished surface due to scrap. In Comparative Examples 17, 19, and 21, since the A / L value exceeded 0.300, the chip discharging property for discharging chips to the outside of the machining diameter was improved, but on the other hand, the rigidity of the small-diameter bar-shaped part Decreased, vibrations such as chatter occurred, the roughness of the machined surface became remarkable, and chattering occurred. Therefore, it was confirmed that the range definition of 0.050 ≦ A / L ≦ 0.300 is necessary.
In Invention Examples 1 to 4, the cutting edge at the tip of the small-diameter bar-shaped part was arranged at one location, Invention Examples 5 to 9 were arranged at 2 locations, and Invention Examples 10 to 15 were arranged at 4 locations on the outer periphery. With this configuration, a plurality of cutting edges can be selected and used by the index, and the substantial tool life is extended by multiplying the number of cutting edges. Accordingly, the inventive examples 5 to 9 have double the number of cutting edges and the inventive examples 10 to 15 have quadrupled compared to the inventive examples 1 to 4, thereby substantially extending the tool life. Further, Examples 5 to 9 of the present invention also had the effect of coating the (TiAl) N coating on the small-diameter rod-shaped portion. In the inventive examples 1 to 9, the cross-sectional shape of the small-diameter bar-like portion excluding the chip pocket portion was made into a substantially circular shape, and in the inventive examples 10 to 15 were made into a substantially square shape. In the case of a substantially circular shape, it was possible to manufacture without reducing the cross-sectional area of the insert for machining the minimum inner diameter more than necessary. In the case of a quadrangular shape, it could be manufactured at a low cost in terms of grinding.

FIG. 1 shows a front view of an inner diameter machining tool of the present invention. FIG. 2 shows a view as seen from the direction of arrow Z in FIG.

Explanation of symbols

1: Cutting edge 2: Small rod portion 3: Shank portion 4: Chip pocket portion 5: Insert 6: Inner diameter of machining A: Longitudinal dimension of the tip pocket portion L: Longitudinal dimension of the small rod portion

Claims (4)

An inner diameter machining tool comprising a small-diameter rod-shaped portion having a cutting edge at a tip portion and a substantially prismatic shank portion integrally connected to the small-diameter rod-shaped portion, and having a chip pocket portion on a rake face of the cutting blade, Inner diameter machining characterized in that 0.050 ≦ A / L ≦ 0.300, where A is the longitudinal dimension from the tip of the cutting edge to the tip pocket, and L is the longitudinal dimension of the small-diameter rod-shaped portion. Tools. 2. The inner diameter machining tool according to claim 1, wherein the inner diameter machining tool has two or more cutting edges on the outer periphery of the tip of the small diameter rod-shaped portion. 3. The inner diameter machining tool according to claim 1 or 2, wherein a cross-sectional shape of the small-diameter bar-like portion excluding the chip pocket portion is substantially circular. 3. The inner diameter machining tool according to claim 1 or 2, wherein a cross-sectional shape of the small-diameter bar-like portion excluding the chip pocket portion is substantially polygonal.

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