JP2008207292A - Cutting insert, holder, and cutting tool - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a cutting tool suitable to cut front and back inner surfaces and right-angle walls on this side and depth side thereof of a work having a working barrier such as a small diameter portion in the intermediate portion inside the work. <P>SOLUTION: The insert 1 forms major cutting edges on opposing acute-angled corners 7 and 8 with the cutting faces formed in different principal surface sides 6 and 7. The cutting edges 7c and 8c are of the positive type. This insert 1 is mounted on the holder 21 to form a cutting tool 51. The insert mounting part has a seating surface which is lowered toward the fore end side on the lateral side of a portion near the fore end surface of the holder 21 and a wall surface. One principal surface 6 of the insert 1 is restrictedly mounted on the seating surface. Side surfaces 9b and 9c are restrictedly mounted on the wall surface. The corners 7 and 8 are oppositely protruded from the lateral side of the holder 21. With this, the corner 7 can cut this side right-angle wall surface and the corner 8 can cut the depth side right-angle wall surface. The arrangement can cut both the right-angle wall surfaces of a work and provides a high fixing force of the insert. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an insert for cutting such as a throw-away tip, a holder to which the insert is mounted, and a cutting tool comprising these.

  Like the cylindrical member to be cut (hereinafter also referred to as a cylindrical member or a workpiece) W shown in FIG. 11, large inner diameter portions 401 and 411 having large inner diameters at the portions near the left and right ends, and inward toward the inner peripheral surface Each of which has a processing barrier portion (also referred to as a small inner diameter portion) 421 projecting at a small diameter and a right-angle wall surface (step portion) 403, 413 at the boundary between the inner diameters (differences). When machining (cutting) the inner peripheral surface and both right-angle wall surfaces (steps) 403 and 413 by turning, rechucking (repeating the chuck) of the workpiece W is performed in order to finish it with high accuracy. However, it is necessary to perform the processing with one chuck (one chuck). Thus, the most basic processing method in the case of processing with one chuck is as follows. In this specification, when the cylindrical member W is chucked by the chuck claw 501 on the left side in the figure, the side on which the cutting tool is inserted (right side in the figure) is referred to as the front side, and the chuck on the opposite side. The side to be done is called the back side. Of the right-angle wall surfaces, as a rule, those facing the side where the cutting tool is inserted are called front-facing right-angle wall surfaces, and those facing the opposite (back) side are called back-facing right-angle wall surfaces.

  That is, the most basic processing method is that the inner peripheral surface of the small inner diameter portion 421, the inner peripheral surface of the large inner diameter portion 401 on the near side, and the front-facing right-angle wall surface (steps) connected thereto. Part) 403 is cut with a first cutting tool 110 in which a triangular insert 100 for cutting is fixed to a holder 105 as shown in FIG. For example, as shown in FIG. 13, the second cutting tool 130 in which the insert 120 is fixed to the holder 125 is used to cut the surface and the back-facing right-angle wall surface (step portion) 413. This is because the front-facing right-angle wall surface 403 of the different-diameter portion on the near side can be processed by the first cutting tool 110, but the rear-facing right-angle wall surface 413 of the different-diameter portion on the back side is processed by the second cutting tool 130 This is because it cannot be done. That is, conventionally, the above-described processing basically requires two cutting tools (hereinafter also simply referred to as tools). However, when such a method is used, the tool needs to be changed during the machining, and accordingly, the machining cycle is complicated, and the machining man-hour is increased, so that the machining efficiency is lowered.

  Such a problem is caused by a cutting tool (for example, having two inserts fixed at a sufficient interval so that the two perpendicular wall surfaces 403 and 413 of the cylindrical member W described above can be processed at the tip of one holder. , Refer to the technology described in Patent Document 1), and can be solved for a while by applying a feed with a necessary cut. However, in the cutting tool in which the two inserts are fixed while maintaining the interval in this way, when the region of the small inner diameter portion 421 in the cylindrical member W becomes long, the interval between the mounting positions of the two inserts increases. There is a problem that the length of the cylindrical member that can be processed is limited. Moreover, the cutting tool which has the insert attachment position corresponding to a process of a cylindrical member is each required, and the versatility of a cutting tool will be lost.

Therefore, there is a tool described in Patent Document 2 as a cutting tool that solves such problems. In this case, one insert having the first and second corners (cutting edges) is pressed (attached) to the tip of the holder, and then tightened with a screw in the axial direction of the holder, thereby fixing the insert. It is made. The cutting tool described in Patent Document 2 is formed by attaching a plate-like insert to the tip end surface of the holder. In the attached state, the insert protrudes on both sides sandwiching the axis of the holder, and the rake surfaces are mutually connected. It is set as the structure which has the cutting blade which faces a different surface. Thus, according to this, the inner peripheral surface and the right-angle wall surface (right-facing right-angle wall surface) of the large inner diameter portion on the front side can be processed with one cutting edge, and the other cutting edge on the back side. Processing of the inner peripheral surface of the large inner diameter portion and the right-angle wall surface (the right-angle wall surface facing back) is also possible.
JP 2005-7556 A Japanese Patent Laid-Open No. 9-267201

  As described above, according to the cutting tool described in Patent Document 2, the problem in the case of using two cutting tools is solved, and there is no problem in the cutting tool described in Patent Document 1. However, in the case of using the cutting tool described in Patent Document 2 (hereinafter also simply referred to as the prior art), there are the following problems to be solved. This is because, in the cutting tool described in Patent Document 2, in a state where the insert is pressed against the tip end surface of the holder, a screw member is placed in the mounting (fixing) through hole opened in the center of the insert. Through the mounting structure, the insert is attached by screwing it into a screw hole provided in the front end surface of the holder.

  In the cutting tool described in Patent Document 2 having such a mounting structure, the insert is positioned between two walls provided so as to prevent rotation around the axis of the holder. There is a problem that it is difficult to secure a sufficient fixing force against the cutting force that is sometimes received. For this reason, in this prior art, there existed a problem that insert was easy to move, and as a result, there existed a difficulty in generation | occurrence | production of chatter and maintenance of processing precision. This is because the fixing of the insert depends on the tightening by the screw member screwed in the axial direction of the holder. That is, in such fixing, the existence of a gap between the outer peripheral surface of the screw and the through hole of the insert and the cutting resistance (main component force) exert an action of bending the screw member. Insert is easy to move.

  On the other hand, in order to increase the fixing force of the insert, it is necessary to use a screw member having a large diameter. For this purpose, it is necessary to enlarge the front end surface of the holder. On the other hand, in this case, it may not be used for processing a cylindrical member having a small inner diameter. Also, it is difficult to increase the cutting edge length in the insert due to the problem of cutting resistance. Therefore, the radial width of the right-angle wall surface (step portion) on the back side of the cylindrical member W as described above is large. In this case, it is not suitable for the processing. Further, since the insert is pressed and fixed to the front end surface of the holder, the smaller the front end surface is, the smaller the pressing area of the insert (the holding area at the time of mounting) is, and thus the fixing force is reduced. As described above, when the conventional technique described in Patent Document 2 is used, it may not be used for small diameter machining. Furthermore, since the insert described in the document has a special shape, there is a problem that the manufacturing cost is high.

  The present invention has been made in view of such problems, and has a processing barrier portion such as a small-diameter portion in an internal intermediate portion, like the above-described cylindrical member, It is an object of the present invention to provide a cutting tool that is suitable for those that require machining of the right-angle wall surfaces on the near side and the rear side (the right-angle wall surface facing forward and the right-angle wall surface facing inward).

In order to achieve the above object, the present invention according to claim 1 is plate-shaped and has two acute corners facing each other on its main surface, and each of the corners has a different rake face. It is formed on the surface side,
"When the two opposing corners are connected by a diagonal line, the cutting blades are in a positional relationship sandwiching the diagonal line, and the cutting edges at different corners" or "Both cutting edges that sandwich the corner at each corner" It is a positive type with a clearance angle.

  The present invention according to claim 2 is the insert according to claim 1, wherein the insert is for internal diameter machining. According to a third aspect of the present invention, in the first or second aspect, the insert includes a through-hole penetrating in the thickness direction of the insert so as to be screwed to the holder. This is an insert. Furthermore, the present invention according to claim 4 is characterized in that the through hole is provided to be unevenly distributed on one of the two corners facing each other on the main surface. The insert according to claim 3.

The present invention according to claim 5 is a holder for attaching the insert according to any one of claims 1 to 4, wherein the holder is directed to a side portion near the tip surface of the holder toward the tip side of the holder. An insert mounting portion comprising a seat surface that is low and a wall surface formed in a standing manner on the seat surface,
The insert mounting portion is configured such that when the insert is seated on the seat surface with its one main surface and the side surface of the insert is constrained by the wall surface, each corner of the insert has a plan view of the seat surface. , Projecting in opposite directions from the side near the front end surface of the holder, one corner is located on the front end side of the holder, and the other corner is located on the rear end side of the holder. At the one corner located at, the front right-angle wall perpendicular to the rotation axis of the member to be cut can be turned and positioned on the rear end side of the processing barrier portion protruding inward on the inner peripheral surface of the member to be cut. At the other corner, the cutting edge at each corner is attached with a cutting edge angle so that the right-angled wall surface at right angles to the rotation axis of the member to be cut can be turned in the processing barrier section. A holder characterized by comprising is formed so as to be.

The present invention described in claim 6 is an insert according to any one of claims 1 to 4 and a cutting tool for machining an inner diameter formed by attaching the insert to an insert mounting portion of a holder,
The insert mounting portion includes, on the side portion closer to the tip end surface of the holder, a seat surface that is lowered toward the tip end side of the holder, and a wall surface that is formed so as to stand up on the seat surface.
With respect to this insert mounting portion, the insert is seated with one main surface thereof seated on the seating surface and the side surface of the insert is restrained by the wall surface,
In the mounted state, each corner of the insert protrudes on the opposite side from the side portion near the tip surface of the holder when the seat surface is viewed in plan, and one corner is the tip side of the holder The other corner is located on the rear end side of the holder, and at one corner located on the front end side of the processing barrier portion protruding inward on the inner peripheral surface of the member to be cut, A front-facing right-angle wall surface that is perpendicular to the rotation axis of the workpiece can be turned, and at the other corner located on the rear end side, a back-facing right-angle wall surface that is perpendicular to the rotation axis of the workpiece is included in the processing barrier portion. The cutting tool is characterized in that a cutting edge angle is given to a cutting edge at each corner so that turning can be performed.

  According to the cutting tool of the present invention, one-chuck is used in internal turning (machining) or inner diameter machining of a member to be cut (cylindrical member) having a machining barrier portion (convex portion) projecting inwardly on the inner circumferential surface. The inner peripheral surface of the large inner diameter portion on the near side and the far side of the processing barrier portion, and the right side wall surface on the near side and the back side in the processing barrier portion (the front right angle wall surface, the back right angle wall surface) in the insert By using two corners (also called cutting edges), processing can be performed without problems. In addition, unlike the conventional technology in which the insert is fixed to the front end surface of the holder and screwed, it is mounted flat on the seat surface of the insert mounting portion formed on the side near the front end surface of the holder. Is. Therefore, as compared with the prior art, the fixing force in mounting the insert can be increased by the amount of flat mounting. Thus, according to the cutting tool of the present invention, it is effective in preventing the occurrence of insert movement and chatter during cutting, and therefore high-precision machining can be performed.

  In particular, in the inner diameter processing (or inner surface processing) of a cylindrical member with a small inner diameter, such as a small cylinder (shaft) part whose inner diameter is less than 10 mm, only a very thin holder can be used because it is inserted into the inside. For this reason, according to the conventional technique in which the insert is fixed with a screw while being pressed against the front end surface of the holder, its mounting area (pressing area) is small and a sufficient fixing force cannot be obtained. This problem becomes more conspicuous as the holder (cutting edge) needs to have a larger amount of protrusion, and the holder must be made relatively thin. On the other hand, in the present invention, the seating surface in the insert mounting portion can be taken sufficiently large in the front and rear (longitudinal direction) at the portion near the tip surface of the holder, so that it is used for inner surface processing of a cylindrical member having a small inner diameter. Even when embodied as a cutting tool, there is an effect that a sufficient fixing force can be secured in the mounting of the insert.

  Moreover, the insert which concerns on this invention can be formed based on the insert raw material which makes a plate shape with a parallelogram or a rhombus, for example. That is, it can be produced by forming cutting edges at two sharp corners facing (diagonal direction) in the insert material with different rake faces (different main faces). Therefore, as compared with the insert having a special shape like the insert of the prior art, the cost can be reduced because a dedicated insert material is not required.

  The best mode for carrying out the present invention will be described in detail with reference to the drawings (see FIGS. 1 to 9). In the figure, reference numeral 1 denotes an insert for inner diameter processing that constitutes the cutting tool 51 of the present invention, which is a plate-like one that has a substantially rhombic shape in plan view at a constant thickness, and penetrates in its own thickness direction. This is a throw-away type (throw-away tip) with a hole (through hole) 3 with a taper seat for a screw. The insert 1 has corners (noses) 7 and 8 of two sharp edges facing each other on its main surfaces 5 and 6, and the cutting edges have rake faces 7 a and 8 a on different main surfaces 5 and 6, respectively. Is formed. The corners 7 and 8 of the respective cutting edges have no nose radius (0) or are minute rounds close to zero. Then, the cutting edges 7b, 7c, 8b, and 8c are formed by using the corners 7 and 8 as a brush. However, when the two opposite corners 7 and 8 are connected by a diagonal line (not shown), the cutting edges 7c and 8c at the different corners 7 and 8 are in a positional relationship sandwiching the diagonal line, Both are positive types with a clearance angle (for example, 13 degrees) for processing the inner peripheral surface. Hereinafter, the cutting edges 7c and 8c are also referred to as horizontal cutting edges 7c and 8c in this specification. In this embodiment, the other cutting edges 7b and 8b at the corners 7 and 8 are given a clearance angle when attached to the holder 21 as will be described later, and therefore the insert itself is of a negative type. However, it may be of a positive type. In the present specification, the other cutting edges 7b and 8b are also referred to as front cutting edges 7b and 8b. In this specification, a side cutting edge and a front cutting edge are used to distinguish two cutting edges at each corner.

  Further, the insert 1 has two major corners 7, which are opposed to each other at a portion (lower right in FIG. 1) which is one of the two obtuse corners 12, 13 on the main surfaces 5, 6. 8 is cut in parallel to a diagonal line (not shown) to form a surface, and a side surface 9b that forms this surface and a side surface 9c that continues to the front cutting edge 8b of the upper right corner (cutting edge corner) 8 in FIG. As will be described later, when being attached to the chip attachment portion 31 of the holder 21, it is restrained by the wall surface.

  In the insert 1 of this example, the through-hole 3 is a diagonal line (straight line) (not shown) that connects the corners 7 and 8 (or the vicinity of the corners 7 and 8) of two acute angles facing each other on the main surfaces 5 and 6. However, it is not located at the center (intermediate position), but is slightly deviated (shifted) near the lower left cutting edge (corner) 7 in FIG. In this way, when the insert 1 is fixed to the chip mounting portion 31 of the holder 21, the protrusion amount T1 of the lower left corner (cutting edge corner) 7 in FIG. This is because the protrusion amount T2 of the upper right corner (cutting edge corner) 8 can be secured large, and even when the radial width of the back-facing right-angle wall surface 413 is wide, it can be handled (processed). In this example, breaker grooves are recessed in the rake faces 7a and 8a of the corners 7 and 8 of the respective cutting edges. The nose angles of the two acute corners 7 and 8 are 70 degrees for the corner 7 and 75 degrees for the corner 8.

  Next, the holder 21 for mounting the above-described insert 1 will be described (refer mainly to FIGS. 3 to 8). The holder 21 is formed of a holder main body portion 23 that extends straight in a rod shape and an insert mounting portion 31 provided on one side of the portion near the tip. The holder main body 23 has a crescent-shaped large-diameter shank portion 25 and a large-diameter shank portion 25 so as to be inserted into the workpiece. It consists of a small-diameter shank portion 27 on the distal end side that has been cut away and reduced in diameter. An insert mounting portion 31 to which the insert 1 is fixed is formed in a portion of the small-diameter shank portion 27 close to the distal end surface 28 so that the insert 1 is fixed (see FIGS. 7 and 8).

  The insert mounting portion 31 includes a flat (planar) seating surface 33 formed so that the insert 1 is seated in a flat state, and an obtuse angle portion 13 that faces the obtuse angle corner 12 in plan view of the insert 1. Wall surfaces 35 and 36 that stand up at the base end side of the holder 21 are provided so as to constrain the two side surfaces, that is, the side surface 9b provided on the side surface and the side surface 9c in a direction continuous to the front cutting edge 8b. However, when the insert 1 is constrained, the two wall surfaces 35 and 36 have a relief portion 37 that escapes the obtuse corner 13 when the insert 1 is constrained. The two wall surfaces 35 and 36 are formed so that the corners (cutting edge corners) 7 and 8 protrude on opposite sides of the holder 21 when the side surfaces 9b and 9c of the insert 1 are constrained. , 8 are formed such that predetermined cutting edge angles (α7, α8) and cutting edge angles (β7, β8) are given to the front cutting edges 7b, 8b and the side cutting edges 7c, 8c, respectively. 1).

  Further, as shown in FIG. 3, the seat surface 33 is an inclined surface that is lowered toward the tip surface 28 of the small-diameter shank portion 27, and the inclination angle θ <b> 1 in a side view (FIG. 3) is For example, it is set to 10 degrees. By doing in this way, even if each front cutting edge 7b, 8b in insert 1 is a negative type, a front relief angle can be secured, respectively. Further, when the insert 1 is attached, the seating surface 33 has the height of the tip of each corner 7 and 8 at the position opposite to the inner peripheral surface of the workpiece W, as shown in FIG. It is set to approach the height of (rotating axis G). That is, since the seating surface 33 of the holder 21 is formed so as to become lower toward the tip end surface 28 side, there is no problem in centering of both cutting edges. The inclination angle θ1 may be set according to dimensions such as the size and thickness of the insert 1. When the inclination angle θ1 is small and the front cutting edges 7b and 8b are negative, the front clearance angle 7b and 8b may be formed as a positive type.

  Further, a screw hole 34 penetrating in the direction perpendicular to the seat surface 33 is formed at the center or substantially the center of the seat surface 33, and the insert 1 is flattened on the seat surface 33 with one main surface (plate surface) 6. In a state where the two side surfaces 9b and 9c are pressed against the wall surfaces 35 and 36 in a state of being placed, the screw 40 is passed through the through hole 3 of the insert 1 and screwed into the screw hole 34. The insert 1 is fixed by screwing. In this fixed state, the two corners 7 and 8 are a corner 7 located on the opposite side of the seating surface 33 and a corner 8 on the main surface 6 side that contacts the seating surface 33. As shown in FIG. 1, one corner 7 is located on the front end side of the holder 21, and the other corner 8 is located on the rear end side of the holder 21.

  Thus, when the insert 1 is fixed to the insert mounting portion 31, the corners 7 and 8 project to the opposite side of the small diameter shank portion 27 when the seat surface 33 is viewed in plan (viewed from above). The amounts protrude (overhang) as T1 and T2, respectively (see FIGS. 1 and 2). In this attached state, in this embodiment, the cutting edges at the corners 7 and 8 have a predetermined cutting edge angle (α7, α8) and a predetermined cutting edge angle (β7, β8), respectively, as described above. Has been granted. That is, the front-facing right-angle wall surface 403 that is perpendicular to the rotation axis G of the workpiece out of the processing barrier portion 421 that protrudes inwardly on the inner peripheral surface of the workpiece W at one corner 7 located on the tip side thereof. In the other corner 8 positioned on the rear end side, the back-facing right-angle wall surface 413 perpendicular to the rotation axis G of the workpiece can be turned at the other corner 8 that can be turned. For reference, α7 is 8 degrees, α8 is 3 degrees, β7 is 12 degrees, and β8 is 12 degrees. In this embodiment, the corner 8 on the main surface 6 side that contacts the seating surface 33, that is, one side 25 a of the large-diameter shank portion 25 among the one side of the small-diameter shank portion 27 is cut and removed in a crescent shape. As described above, the protruding amount T2 of the corner 8 protruding to the side is set to be larger than the protruding amount T1 of the corner 7 positioned on the opposite side of the seating surface 33. Of these, the width of the back-facing right-angle wall surface 413 is set larger than the width in the radial direction of the workpiece.

  Next, an example of processing (turning) the inner surface of the workpiece W shown in FIG. 11 with such a cutting tool 51 will be described with reference to FIG. In this embodiment, the lower left corner 7 in FIG. 1 and the cutting edges 7b and 7c sandwiching these corners are cutting edges for processing the front-facing right-angle wall surface 403, and the upper right corner 8 in FIG. The blades 8b and 8c are where the back-facing right-angle wall surface 413 is processed. A portion closer to the tip of the cutting tool 51 of this embodiment is inserted from the front side of the workpiece W inside the workpiece W that is held and rotated by a chuck claw (not shown) on the left side of FIG. With respect to the inner peripheral surface of the portion (small inner diameter portion) 421, the tool is laterally fed to the back side so as to have a predetermined cutting amount (see FIG. 10A). After the inner peripheral surface of the small inner diameter portion 421 is processed in this way, the cutting tool 51 is further laterally fed so that the processing corner 8 on the back side is positioned to the left of the end of the large inner diameter portion 411 on the back side.

  Then, the cutting tool 51 is longitudinally fed so that the processing corner 8 on the back side has a predetermined cutting amount on the inner peripheral surface at the back side end of the large inner diameter portion 411. To the inner peripheral surface of the large inner diameter portion 411 on the back side (see FIG. 10-B). Then, when a predetermined cut is made at the position of the back-facing right-angle wall surface 413 on the back side of the small inner diameter portion 421, the lateral feed is stopped, and this time, it is perpendicular to the rotation axis (line) G side of the workpiece W. The cutting tool 51 is longitudinally fed to a position where the processing corner 8 on the back side does not interfere with the inner peripheral surface of the small inner diameter portion 421 (see FIG. 10C). By doing so, the back-facing right-angle wall surface 413 on the back side is processed.

  Next, the cutting tool 51 is laterally fed to the front side, and a position where the front processing corner 7 becomes a predetermined cut with respect to the front right-angle wall surface 403 at the position of the front right-angle wall surface 403 in the small inner diameter portion. To stop the cross feed. Next, it feeds vertically and cuts the front-facing right-angle wall surface 403 (see FIG. 10-D). Then, the longitudinal feed is stopped at a position where a predetermined amount of incision is made with respect to the inner peripheral surface of the large inner diameter portion 401 on the near side, this time, the cutting tool 51 is laterally fed to the near side, and the large inner diameter portion 401 on the near side is The inner peripheral surface is processed (see FIG. 10-E).

  Thus, in the cutting tool 51 of this embodiment, including the right-angle wall surfaces 403 and 413 existing on the near side and the far side of the machining barrier portion (small inner diameter portion) 421 located in the middle of the workpiece W, The inner peripheral surface can be processed without problems with a single chuck. In addition, the above-mentioned processing order of the inner peripheral surface is an example, and it is possible to process from any part, and in the processing of any part, the feed is set in the reverse direction as described above. Also good.

  In the cutting tool 51 of the present embodiment, the above-described workpiece can be processed without problems, but has the following specific effects. That is, the cutting tool 51 of this embodiment is completely different from the conventional technique in which the insert 1 is fixed with being pressed against the distal end surface 28 of the holder 21. That is, in the cutting tool 51 of this embodiment, the insert 1 is mounted flatly on the seat surface 33 of the insert mounting portion 31 formed on the side portion of the holder 21 near the tip surface 28. Therefore, in the above embodiment, the main component force in the cutting force when cutting at the processing corner 7 of the front-facing right-angle wall surface 403 is mainly received by the seat surface 33, so that the fixing force or stability of the insert 1 is increased. Extremely expensive. Therefore, it is effective in preventing the movement of the insert 1 and chattering, and high-precision machining can be performed. In addition, when cutting at the corner 8 for machining the back-facing right-angle wall surface 413, most of the main component force in the cutting resistance is applied to the screw member 40, but even in that case, the screw member 40 has a tensile force (axial force). Therefore, the fixing force of the insert 1 is higher than that in the case where the bending force directly acts on the screw member 40 as in the prior art. Accordingly, when viewed as a total, the fixing force of the insert 1 is higher than that of the prior art, which is effective in preventing the movement and chattering, and enables high-precision machining.

  Moreover, the insert 1 which concerns on this invention can be formed based on the raw material which makes a plate shape with a parallelogram as above-mentioned. That is, it can be easily manufactured by forming cutting edges at two acute corners in the diagonal direction of the material with different rake faces. Therefore, since a specially shaped material is not required unlike the insert in the prior art, the cost can be reduced. The same is true for the holder.

  Furthermore, in the present invention, since the insert is mounted flat with respect to the seating surface at the chip mounting portion, the seating surface is arranged in front of and behind the holder (axial direction) even when the diameter of the tip of the holder is small. Therefore, it is possible to secure a large area for mounting the insert. In other words, since the holding area for securing the insert can be secured large, the fixing force can be achieved even when embodied as for small-diameter machining, compared to the conventional technique where the insert is pressed against the tip of the holder and screwed. The shortage can be easily avoided. Therefore, even a workpiece having an inner diameter of 10 mm or less and having a small-diameter portion therein can process a right-angle wall surface on the back side with a single chuck and one cutting tool. In other words, machining can be performed without problems even in machining of small-diameter workpieces, which has conventionally been considered difficult. For this reason, this type of accessory (shaft component) is extremely suitable for inner diameter processing.

  In the above description, the insert has a shape close to a so-called parallelogram (diamond chip). However, the present invention is not limited to such an insert, and two acute corners facing each other are formed. Widely applicable to inserts having In the above description, the insert with a hole is embodied, but if the workpiece has a relatively large inner diameter, the insert can be embodied without using a chip with a hole. That is, any means can be used as the insert clamping method as long as it is inserted into the workpiece and there is no problem in processing. And it can be widely embodied in an insert regardless of the throw-away method. Furthermore, in the above example, the cutting edge located on the tip side of the cutting tool (holder) is located on the side opposite to the seating surface, and the cutting edge located on the side away from the tip of the cutting tool (holder) is located on the seating surface side. Although it is embodied as being located, it is needless to say that this can also be embodied as the opposite.

The figure which looked at the cutting tool formed by attaching the insert which concerns on this invention to the insert attachment part of a holder from the one main surface (seat side of through-hole) side of an insert, and the enlarged view of the insert in the state. The figure seen from the back surface (opposite side) of FIG. 1, and the enlarged view of the insert in the state. The figure which looked at FIG. 1 from the arrow A direction, and the enlarged view containing the insert vicinity. The perspective view which looked at the cutting tool of FIG. 1 from the lower left, and the enlarged view containing the insert vicinity. The perspective view which looked at the cutting tool of FIG. 1 from the upper right, and the enlarged view containing the insert vicinity. The perspective view which looked at the cutting tool of FIG. 1 from the lower right of FIG. 2, and the enlarged view containing the insert vicinity. The enlarged view of the chip | tip attachment part of the holder which removed the insert in FIG. The enlarged view of the chip | tip attachment part of the holder which removed the insert in FIG. It is the enlarged view which looked at the cutting tool of FIG. 1 from the left end, Comprising: The figure explaining the core height of both cutting edges. Explanatory drawing of the state which processes a workpiece | work with the cutting tool of FIG. The figure explaining a cylindrical to-be-cut member (cylindrical member). Explanatory drawing of the conventional basic processing method which processes the cylindrical member of FIG. Explanatory drawing of the conventional basic processing method which processes the cylindrical member of FIG.

Explanation of symbols

1 Insert 3 Through-holes 5 and 6 Main surface 7 and 8 of the insert Two opposing acute corners (cutting edge corner)
7a, 8a Rake face 7b, 8b Cutting edge (front cutting edge)
7c, 8c Cutting edge (Horizontal cutting edge)
9b, 9c Side surface 21 of insert to be constrained Holder 28 End face 31 of holder Insert mounting portion 33 Seat surface 35, 36 Wall surface 51 Cutting tool 403 Front-facing right-angle wall surface 413 Back-facing right-angle wall surface 421 Processing barrier section α7, α8 Cutting edge angle β7, β8 Horizontal cutting edge angle W Workpiece (member to be cut)
G Rotating shaft of workpiece

Claims (6)

It has a plate shape and has two acute corners facing each other on its main surface, and each of the corners has a cutting edge formed with a rake face different from the main surface,
When the two opposing corners are connected by a diagonal line, the cutting edge is in a positional relationship between the diagonal lines, and the cutting edge at different corners, or both cutting edges that sandwich the corner at each corner have a clearance angle. Insert characterized by being positive type.   The insert according to claim 1, wherein the insert is for machining an inner diameter.   The insert according to claim 1, wherein the insert includes a through-hole penetrating in a thickness direction of the insert so as to be screwed to the holder.   The insert according to claim 3, wherein the through hole is provided so as to be unevenly distributed on one of the two acute corners facing each other on the main surface. A holder for mounting the insert according to any one of claims 1 to 4, wherein a seating surface that is lowered toward a tip end side of the holder on a side portion near a tip end surface of the holder, and the seat An insert mounting portion including a wall surface formed in a shape that stands up on the surface;
The insert mounting portion is configured such that when the insert is seated on the seat surface with its one main surface and the side surface of the insert is constrained by the wall surface, each corner of the insert has a plan view of the seat surface. , Projecting in opposite directions from the side near the front end surface of the holder, one corner is located on the front end side of the holder, and the other corner is located on the rear end side of the holder. At the one corner located at, the front right-angle wall perpendicular to the rotation axis of the member to be cut can be turned and positioned on the rear end side of the processing barrier portion protruding inward on the inner peripheral surface of the member to be cut. At the other corner, the cutting edge at each corner is attached with a cutting edge angle so that the right-angled wall surface at right angles to the rotation axis of the member to be cut can be turned in the processing barrier section. Holder, characterized in that formed comprising as. An insert according to any one of claims 1 to 4, and a cutting tool for machining an inner diameter formed by attaching the insert to an insert mounting portion of a holder,
The insert mounting portion includes, on the side portion closer to the tip end surface of the holder, a seat surface that is lowered toward the tip end side of the holder, and a wall surface that is formed so as to stand up on the seat surface.
With respect to this insert mounting portion, the insert is seated with one main surface thereof seated on the seating surface and the side surface of the insert is restrained by the wall surface,
In the mounted state, each corner of the insert protrudes on the opposite side from the side portion near the tip surface of the holder when the seat surface is viewed in plan, and one corner is the tip side of the holder The other corner is located on the rear end side of the holder, and at one corner located on the front end side of the processing barrier portion protruding inward on the inner peripheral surface of the member to be cut, A front-facing right-angle wall surface that is perpendicular to the rotation axis of the workpiece can be turned, and at the other corner located on the rear end side, a back-facing right-angle wall surface that is perpendicular to the rotation axis of the workpiece is included in the processing barrier portion. A cutting tool in which a cutting edge angle is given to a cutting edge at each corner so that turning can be performed.

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