JP2004074322A - Throwaway tip and cutting tool using it - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a throwaway tip which is strongly fixed while enhancing the accuracy of mounting position of a cutting edge. <P>SOLUTION: This throwaway tip 5 formed into an approximately rod shape, having the cutting edge 6 at one end in a longitudinal direction and having at the other end, a cut surface 9 having a short part in the longitudinal direction, is inserted into a hole 3 arranged in the tip of a holder 2, and also fixed by abutting a fixing member 10 attached to the holder 2 and the cut surface 9 to each other. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a throw-away insert having a substantially rod shape, and more particularly to a throw-away insert having a high cutting edge position accuracy and a high binding force, and a cutting tool using the same.
[0002]
[Prior art]
Conventionally, as a cutting tool used for grooving or threading, a substantially bar-shaped indexable insert 21 having a cutting edge at one or both ends as shown in FIG. 9 is inserted into a hole 21 a of a holder 22. And what is fastened and fixed with bolts 23 etc. is known.
[0003]
Japanese Patent Application Laid-Open No. 2001-71204 discloses a method of fixing a bar-shaped indexable insert having cutting edges at both ends by contacting a stored cutting edge with a bolt fitted from the rear end side of a holder. It describes a method for fixing.
[0004]
[Problems to be solved by the invention]
However, the conventional bar-shaped indexable insert shown in FIG. 9 has a problem that the projection length is easily varied when the tip 21 is replaced because the projection length of the bar is variable, and the cutting edge is displaced. In addition, since the side surface of the bar is pressed and fixed with bolts 23, the binding force in the rotating direction of the chip 21 is particularly weak, and the cutting edge rotates due to rotation of the chip 21 during cutting, or the chip 21 becomes loose. There was a problem that it was easy.
[0005]
Further, in the cutting tool described in Japanese Patent Application Laid-Open No. 2001-71204, there is a possibility that the cutting edge that comes into contact with the bolt may be damaged by vibration during mounting or during cutting, and the opposite cutting edge is used. In this case, there is a problem that the positional accuracy of the cutting edge is deviated because the degree of chipping or wear of the cutting edge is different each time.
[0006]
The present invention has been made in order to solve such a problem, and an object thereof is to provide a cutting tool using the indexable insert which can increase the mounting position accuracy of the cutting blade and can be firmly restrained. It is in.
[0007]
[Means for Solving the Problems]
By adopting the following configuration, the present inventors can improve the mounting position accuracy of the cutting blade even at the time of chip replacement, and can particularly improve the restraining force in the rotation direction of the chip, thereby achieving stable processing. Invented to be possible.
[0008]
That is, the throwaway tip of the present invention has a substantially bar shape, has a cutting edge at one end in the longitudinal direction, and has a cut surface having a short portion in the longitudinal direction at the other end. is there.
[0009]
Here, the cut surface is cut obliquely with respect to the longitudinal direction, in particular, so that the length in the longitudinal direction is reduced continuously or stepwise. It is desirable that the cut angle of the cut surface with respect to the end surface is 30 to 60 °.
[0010]
Further, it is preferable that a side surface continuous with the cut surface is formed of a round bar.
[0011]
Furthermore, the cutting tool of the present invention inserts the above-mentioned throw-away tip into a hole provided at the tip of the holder, and abuts the fixing member attached to the holder and the cut surface to make the cut-away tip. Is fixed.
[0012]
BEST MODE FOR CARRYING OUT THE INVENTION
FIG. 1 is a plan view of a cutting tool for inner diameter machining, which is an example in which an embodiment of the indexable insert of the present invention is mounted in a holder, and FIG. 1 is a view of the cutting tool of FIG. 2 and FIG. 3 showing the cutting tool of FIG. 1 viewed from the direction B.
[0013]
According to FIG. 1, a cutting tool (hereinafter, simply abbreviated as a tool) 1 has a hole 3 formed at the tip of a holder 2, and a throw-away chip (hereinafter, simply abbreviated as a chip) 5 is mounted in the hole 3. Do it.
[0014]
According to the present invention, the tip 5 has a substantially bar shape, has a cutting edge 6 at one end in the longitudinal direction, and has a cut surface 9 having a portion whose length in the longitudinal direction is short at the other end. By fixing the cut surface 9 in contact with the cylindrical fixing member 10 attached to the holder 2, the cutting blade 6 can be accurately positioned and mounted even when the chip 5 is replaced, and the chip 5 can be mounted. Since the tip 5 can be firmly restrained, it is possible to prevent the tip 5 from rotating and the position of the cutting edge 6 from shifting or the tip 5 from being loosened during cutting.
[0015]
According to FIG. 1, the cut surface 9 of the chip 5 is cut obliquely with respect to the longitudinal direction of the rod-shaped body, and has advantages of high dimensional accuracy in manufacturing and easy manufacturing. The cut angle θ of the cut surface 9 (the angle of the cut surface with respect to the imaginary end surface perpendicular to the longitudinal direction of the rod-shaped body) is 30 to 60 °, particularly 40 to 50 °, to improve the chip binding force and to reduce the cut surface 9. This is desirable from the viewpoint of prevention of loss and easy production.
[0016]
Further, in the present invention, the shape of the cut surface is not limited to the above configuration, and as shown in FIG. 4, (a) a configuration in which the length in the longitudinal direction is gradually reduced, and (b) a cut surface 9 is formed. The cut surface 9 may be cut so that the length changes continuously or stepwise, such as a configuration in which the length is continuously reduced so as to form a curved surface. Any configuration, such as a configuration in which a concave portion 18 having a reduced length in the longitudinal direction is provided at the central portion, or a combination thereof, may be employed. In order to prevent excessive wear and breakage, a structure in which the length is reduced continuously or stepwise, particularly a structure cut obliquely, is best.
[0017]
Here, according to the present invention, the dimensions of the cutting edge 6 and the like of the tip 5 are also processed by using the same jig as the holder 2 having the fixing member 10 in the cutting edge processing step at the time of manufacturing the tip 5. High-precision chip processing becomes possible.
[0018]
Further, in FIGS. 1 to 3, a first slit groove 11 communicating with the hole 5 for fixing the chip 5 in the longitudinal direction is provided at the tip of the holder 2, and the end of the first slit groove 11 is shown in FIG. As shown in FIG. 3, it communicates with a second slit groove 14 arranged in a direction orthogonal to the substantially rod-shaped hole, and has a U-shape in which the groove 11 is open on the tip side of the second slit groove 14. ing. Then, a bolt 12 is screwed into the holder 2 so as to connect between the first slit grooves 11 of the holder 2 (a U-shaped opening), so that the wall surface of the hole 3 is formed in the holder restraining portion 15 of the chip 5. The side surface of the chip 5 is pressed and restrained by the holder 2.
[0019]
Note that the method of restraining the chip of the holder 2 is not limited to the method of FIGS. 1 to 3. For example, as shown in FIGS. 5A and 5B, a holding plate having a part of the wall surface of the substantially rod-shaped hole 5. 13 may be provided separately from the holder 2 and the holding plate 13 may be fixed to the holder 2 by bolting. FIGS. 5A and 5B are views showing a modified example viewed from the direction A in FIG.
[0020]
According to FIG. 6, which is an enlarged view of the chip 5 in FIG. 1, the chip 5 includes a holder restraining portion 15 fixed in the hole 3 of the holder 2 and a projecting portion 16 projecting from the holder 2. Although the protrusion 16 is formed so that the diameter r ₂ of the protrusion 16 is smaller than the diameter r ₁ of the restraint 15, the present invention is not limited to this, and the diameter r ₁ of the holder restraint 15 and the protrusion r 16 diameter _{r 2} of the may be the same. The ratio of r ₂ / r ₁ is desirably 0.15 to ₁ , particularly 0.3 to 0.8, in that the inside diameter of a small diameter can be machined and the restraining force of the holder can be improved. Furthermore, in terms of being able to firmly restrain the chip 5 and reducing the size of the chip 5, the ratio L ₂ / L of the length L ₂ of the protruding portion 16 to the entire length L of the chip 5 is 0.4 to 3, especially 0.1 to 0.3. It is desirable to be 5 to 2. In addition, the diameter and the length of the protrusion 16 can be changed according to the use of the chip 5, and even if the holder 5 has the same diameter and the same length, the size of the protrusion 16 is different. It can be mounted using the same holder 2.
[0021]
As shown in FIG. 6 and FIG. 7A which is a projection view of the chip 5 of FIG. 6 viewed from the direction A, the cutting edge 6 is slightly s = 0. It is formed on the outer side in the cross-sectional direction at 1 to 1.0 mm to prevent the protrusion 16 from interfering with the work material. The tip of the cutting blade 6 may be a sharp edge, but may be an R surface with R = 0.2 mm or less. Here, as a method of forming the cutting edge 6, a rod-shaped projection 16 may be manufactured, and then a portion of the projection 16 at a rear end of the cutting blade 6 may be polished or manufactured. The rod-shaped body may be manufactured such that is larger than the rod-shaped protrusion 16.
[0022]
A rake face 7 is formed on the upper surface of the cutting blade 6, and the rake face 7 has a concave curved surface so as to function as a breaker. On the other hand, a front cutting edge 6a is formed on the distal end face side of the cutting edge 6, and a horizontal cutting edge 6b is formed on the side surface side of the cutting edge 6, respectively. Further, a notch 8 is formed between the rake face 7 and the protruding portion 16 for efficiently discharging chips.
[0023]
Further, as shown in the chip 5 of FIG. 6, the protruding portion 16 of the chip 5 is basically formed in a circular cross section. As shown in FIG. 7B, which is a cross-sectional view taken along the line BB of the chip shown in FIG. May be formed by cutting out the shape.
[0024]
Furthermore, the holder restraining portion 15 has a circular cross section in terms of easiness of processing, shortening of a manufacturing process, improvement in mounting accuracy of the chip 5, and improvement in restraining force, that is, the holder restraining portion 15 is a round bar. desirable.
[0025]
According to the present invention, as shown in FIG. 8, in order to increase the binding force of the chip 5, a concave notch 20 is provided on the chip side surface, and the screw member 21 fixed to the holder 2 is provided in the notch 20. It is also possible to insert.
[0026]
On the other hand, the tip 5 is made of cemented carbide or cermet, and the fixing member 10 may be made of steel, but may be made of cemented carbide, cermet or ceramic in terms of wear resistance and plastic deformation resistance. It is desirable that the fixing member 10 is formed in a columnar shape that can be accurately aligned with the portion that comes into contact with the chip 5 and that is easy to process. May have a plane shape or a polygonal column shape.
[0027]
On the other hand, the insert and the tool of the present invention can be used for turning, but are particularly suitable for machining of a very small diameter having a diameter of 4 mm or less, particularly 3 mm or less. It is possible to achieve high-quality processing having an accurate and smooth finished surface.
[0028]
【The invention's effect】
As described in detail above, according to the present invention, the tip and the cutting blade can be always mounted at a predetermined position by abutting and fixing the cut surface provided at the other end to the fixing member, and The positioning can be performed easily and with high accuracy, and the restraining force of the tip in the rotation direction can be increased to prevent the cutting blade from being displaced and the tip from being loosened. Furthermore, since the positioning of the processing can be easily performed even when the cutting blade is processed, a chip having high dimensional accuracy can be manufactured.
[0029]
Further, by making the cut surface oblique, a chip can be easily manufactured with high dimensional accuracy and without local stress concentration.
[0030]
Further, the insert and the tool of the present invention are particularly suitable for processing an extremely small inner diameter having a diameter of 4 mm or less. Even in such an extremely small inner diameter processing, high-precision and high-quality processing can be stably achieved.
[Brief description of the drawings]
FIG. 1 is a plan view showing an embodiment of a cutting tool in which a throw-away tip of the present invention is mounted on a holder.
FIG. 2 is a view of the cutting tool of FIG. 1 as viewed from a direction A.
FIG. 3 is a view of the cutting tool of FIG. 1 as viewed from a direction B.
FIG. 4 is a schematic view showing another embodiment of the cut surface of the throw-away tip of the present invention.
FIG. 5 is a sectional view showing another embodiment of the indexable insert of the present invention.
FIG. 6 is an enlarged view of a main part of the throw-away tip of FIG. 1;
7 (a) is a view of the throw-away tip of FIG. 6 viewed from a direction A, and FIG. 7 (b) is a cross-sectional view of FIG. 6 along BB.
FIG. 8 is a plan view showing another embodiment of the indexable insert of the present invention.
FIG. 9 is a plan view showing a state where a conventional bar-shaped throw-away tip is mounted on a holder.
[Explanation of symbols]
1 cutting tool (tool)
2 Holder 3 Hole 5 Indexable insert (tip)
6 Cutting Edge 6a Front Cutting Edge 6b Horizontal Cutting Edge 7 Rake Surface 8 Notch 9 Cut Surface 10 Fixing Member 11 First Slit Groove 12 Bolt 13 Holding Plate 14 Second Slit Groove 15 Holder Restraining Part 16 Projecting Part 18 Recess 19 Notch 20 Screw member

Claims (6)

A throw-away insert, which has a substantially bar shape, has a cutting edge at one end in a longitudinal direction, and has a cut surface having a portion having a short length in the longitudinal direction at the other end. The indexable insert according to claim 1, wherein the cut surface is cut continuously or stepwise so that the length in the longitudinal direction is reduced. The indexable insert according to claim 2, wherein the cut surface is cut obliquely to the longitudinal direction. The indexable insert according to claim 3, wherein a cut angle of the cut surface with respect to a virtual end surface perpendicular to the longitudinal direction is 30 to 60 °. The indexable insert according to any one of claims 1 to 4, wherein a side surface continuous with the cut surface is formed of a round bar. Inserting the throw-away tip according to any one of claims 1 to 5 into a hole provided at the tip of the holder, and abutting the fixed member attached to the holder and the cut surface to remove the throw-away tip. A cutting tool characterized by being fixed.

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