JP2009125842A - Cutting tool - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a cutting tool performing cutting work with high working accuracy in forming a working hole having a predetermined inside diameter on an inner wall surface of a prepared hole provided in advance in a cutting material. <P>SOLUTION: In a boring bar 10, an insert 40 having a cutting blade 53 is attached to an end part outer periphery of a tool body 20 rotated around an axis O, and is inserted into the prepared hole formed in the cutting material in advance, and the inner wall surface of the prepared hole is cut and the working hole having the prescribed inside diameter is formed. A flat land 51 in a flat surface shape is formed on the insert 40 in a quadrangular plate shape, the cutting blade 53 is formed on a ridge line of the flat land 51, and the insert 40 is attached so that the flat land 51 and the axis O are in parallel to each other. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a cutting tool such as a boring bar used when an inner wall surface of a prepared hole formed in advance in a prepared hole is cut into a predetermined inner diameter.

  In recent years, as a cutting tool used for processing a cylinder bore of an engine, for example, a boring bar or the like as shown in Patent Document 1 in which an insert having a cutting edge is detachably attached to the outer periphery of a tip end portion of a tool body is known. It has been.

  Such a boring bar has a cylindrical tool body rotated about an axis, and an insert having a cutting edge is fixed to the outer periphery of the tool body tip side by a clamp screw or the like. This insert has a rectangular flat plate shape, and is attached to the tool body with the cutting edge formed at the side ridge portion of the corner portion of the square surface facing outward in the tool radial direction.

This boring bar is attached to the main end shaft of the machine tool via an adapter or the like, and is rotated at high speed around the axis of the tool body, and is fed in the axial direction of the tool body to be cut. The inner wall surface of the prepared hole is cut by a cutting blade that is inserted into a prepared hole provided in the material in advance and protrudes toward the outer side in the tool radial direction at the tip of the tool body, thereby processing a predetermined inner diameter. Create a hole.
JP 2005-246527 A

  By the way, in the conventional cutting tool as described above, when the tool main body is sent in the axial direction, the cutting blade performs cutting while biting the inner wall surface of the prepared material, but the cutting blade Is formed at the edge of the corner portion of the insert, the tip is sharply pointed, and the inner wall surface of the prepared hole cut by the cutting blade is Depending on the tip shape, it is sharpened. Therefore, particularly when the amount of feed of the tool body in the axial direction is large, there is a problem that the machining surface of the prepared hole of the workpiece becomes rough and the machining accuracy decreases.

  This invention has been made in view of such a problem, and when forming a machining hole having a predetermined inner diameter on the inner wall surface of a prepared hole provided in advance in a workpiece, the machining surface roughness is improved, An object of the present invention is to provide a cutting tool capable of performing cutting with high processing accuracy.

In order to solve the above problems, the present invention proposes the following means.
That is, in the cutting tool according to the present invention, an insert having a cutting edge is attached to the outer periphery of the distal end portion of the tool body rotated about the axis, and is inserted into a prepared hole formed in advance in the work material. A cutting tool that forms a processing hole with a predetermined inner diameter by cutting an inner wall surface, wherein the insert has a rectangular flat plate shape and is provided at the tip side of each corner portion of a rake face that is directed forward in the tool rotation direction. A flat surface-shaped flat land is intersected, and a cutting edge is formed at each intersecting ridge line between the flat land and the rake surface, and the insert is configured so that one of the flat lands is a diameter of the tool body. The flat land and the axis line are attached so as to be positioned on the outer periphery in the direction.

  According to the cutting tool having such a feature, the flat surface-shaped flat land is formed in the insert, and the cutting edge formed at the intersecting ridge line between the flat land and the rake surface is also a straight line when viewed from the front in the tool rotation direction. It becomes a shape. By attaching this insert to the tool body so that the flat land is parallel to the axis of the tool body, the surface of the inner wall of the prepared hole of the workpiece and the tip of the cutting edge are parallel to each other. It is possible to perform cutting along the surface shape of the inner wall surface while increasing the contact length with the inner wall surface of the pilot hole. Therefore, since the inner wall surface can be scraped off into a cylindrical shape centered on the axis, the processed surface roughness of the processed hole can be improved.

  Further, in the cutting tool according to the present invention, the insert is attached so as to be inclined such that a side surface facing the radial direction of the tool body is directed to the outer side in the tool radial direction toward the tip side of the tool body with respect to the axis. An adjustment wedge for pressing the insert toward the tip end side of the tool body and the outer side in the radial direction of the tool body is inserted into the tool rear end side of the insert of the tool body in parallel with the side surface. Yes.

  When setting the amount of protrusion of the cutting edge in the tool radial direction to be suitable for the pilot hole to be machined, or when making the position in the tool radial direction equal when multiple cutting edges are provided By adjusting the insertion amount of the adjustment wedge, the insert is pressed to the tool tip side and the tool body radial direction outside. This makes it possible to adjust the position of the cutting edge in the tool radial direction while maintaining the flat land parallel to the axis.

  In addition, by adopting a configuration in which the insert is pressed in a direction inclined with respect to the axis to adjust the amount of protrusion of the cutting blade in the tool radial direction, compared to a case where the insert is pressed directly outward in the tool radial direction, The amount of movement of the cutting blade in the tool radial direction due to the adjustment amount becomes small. Therefore, it is possible to finely adjust the protruding amount of the cutting blade.

  Further, in the cutting tool according to the present invention, a breaker groove that is recessed so as to recede from the tip side of each corner portion toward the inside is formed on the rake face. The rake face other than the above is characterized in that it is a flat face that does not retreat more than the cutting edge.

  By providing the breaker groove, the chips are divided into short pieces, and the processing of the chips is facilitated, and when the rake face is formed on the two side surfaces of the rectangular flat plate-like inserts opposite to each other, When attaching the insert to the tool body, the abutment area between the insert and the tool body can be secured by bringing the flat surface of the side facing the rear side in the tool rotation direction into close contact with the tool body. The cutting force acting can be reliably received by the tool body, and the cutting edge can be prevented from being broken to extend the life of the insert.

  Further, the cutting tool according to the present invention is characterized in that the end of the flat land in the insert on the tip side of the tool is formed in a convex curved shape.

  When the tool body is sent in the axial direction, the convex curvilinear cutting edge formed on the intersecting ridge line between the convex curved surface and the rake face first comes into contact with the work material, so stress concentration during cutting is concentrated. It can be suppressed and damage to the corner portion of the insert can be prevented.

  According to the cutting tool according to the present invention, when forming a processing hole having a predetermined inner diameter on an inner wall surface of a prepared hole provided in advance in a workpiece, the processing surface roughness is improved and cutting processing with high processing accuracy is performed. Can be applied.

  Hereinafter, a boring bar which is an embodiment of the cutting tool of the present invention will be described with reference to FIGS. FIG. 1 is a partially cutaway longitudinal sectional view showing a boring bar according to an embodiment of the present invention, and FIG. 2 is a front view of the boring bar according to an embodiment of the present invention. As shown in FIG. 1, the boring bar 10 according to the present embodiment includes a tool body 20, a guide pad 30, an insert 40, and an adjustment wedge 60.

  The tool body 20 is made of, for example, a steel material and has a long cylindrical shape formed around the axis O, as shown in FIG. 1, and the tool rear end side (right side in FIG. 1). A mounting portion 21 is formed in which the rear end surface is recessed along the axis O and is attached to a machine tool or the like (not shown).

  A coolant supply hole 22 extending along the axis O is formed in the tool body 20, and one end of the coolant supply hole 22 is opened in the mounting hole 21. Further, a coolant supply path 23 is formed from the tip of the coolant supply hole 22 toward each of a plurality of recessed grooves 25 described later.

  Further, on the outer periphery of the tool body 20, a plurality of pad attachment portions 24 for attaching the guide pads 30 are provided at equal intervals in the circumferential direction as shown in FIG. 6 (six in this embodiment). The pad mounting portion 24 is formed so that the tool body 20 is cut out in a U shape from the outer peripheral side to the inner side in the tool radial direction in the cross section, and this extends in parallel to the axis O.

  Further, a tapered conical surface 29 having a diameter increasing toward the tip is formed on the outer periphery of the tip of the tool body 20, and the conical surface 29 opens toward the tool tip and the tool outer peripheral side. As shown in FIG. 2, a plurality of concave grooves 25 (six in this embodiment) are provided at equal intervals in the circumferential direction, as shown in FIG. 2.

  As shown in FIG. 4 in detail, in the cross section perpendicular to the axis O, the concave groove 25 has its surface facing the rear in the tool rotation direction T gradually inclined forward in the tool rotation direction T toward the outer side in the tool radial direction. An inclined surface 25a is formed, and a groove bottom portion 25b having a concave curved surface is formed so as to continue to the rear side of the inclined surface 25a in the tool rotation direction T. The groove bottom portion 25b is formed with a discharge hole 23a serving as an opening of the coolant supply path 23 described above.

  Further, as shown in FIG. 4, on the rear side in the tool rotation direction T of the concave groove 25, it is continuous with the concave curved surface of the groove bottom portion 25 b and is shallower inward in the tool radial direction than the concave groove 25. An insert mounting portion 26 that opens toward the surface and the outer peripheral surface of the tool is provided. In the insert mounting portion 26, a surface facing the front side in the tool rotation direction T is a contact surface 26a on which a rectangular surface 42 of the insert 40 described later is contacted as a contacted surface. The facing surface is the mounting seat 26b with which the side surface 43 of the insert 40 contacts.

  As shown in detail in FIG. 3, the mounting seat 26 b is gradually inclined inward in the tool radial direction toward the tool rear end side, and an insert mounting for fixing the insert 40 is provided at the center thereof. A screw hole (not shown) is formed.

  Further, a notch for inserting the adjustment wedge 60 so that the outer periphery of the tool main body 20 is cut obliquely toward the inner side in the tool radial direction and toward the front end side of the tool main body on the tool rear end side of the insert mounting portion 26. A portion 27 is provided, and a wedge mounting screw hole 28 is opened in the bottom portion 27 a of the cutout portion 27. The wedge mounting screw hole 28 is provided so as to be inclined toward the tool tip side as its axis k goes inward in the tool radial direction.

  Further, the surface of the notch 27 that faces the front side of the tool is inclined so as to be directed toward the tool tip as it goes inward in the tool radial direction, and the inclination of the notch is formed so that the inclination angle is parallel to the axis k. It is set as the surface 27b.

  The adjustment wedge 60 is made of steel or the like, and as shown in FIG. 3, a wedge screw insertion hole 62 through which a wedge attachment screw 61 for attaching the adjustment wedge 60 to the notch 27 of the tool body 20 is inserted. Is provided. Further, the adjustment wedge 60 is inserted along the inclination of the cutout portion 27, and an insert which will be described later is provided on the surface of the adjustment wedge 60 that is inserted into the cutout portion 27 and facing the tool tip side and the outside in the tool radial direction. A pressing surface 63 that presses 40 is formed.

  Further, the surface of the adjustment wedge 60 facing the inner side in the tool radial direction and the rear end side of the tool is a wedge inclined surface 64 that is in close contact with the notched portion inclined surface 27 b of the notched portion 27. Then, the wedge mounting screw 61 passes through the wedge screw insertion hole 62 and is screwed into the wedge mounting screw hole 28 along the axis k direction so that the pressing surface 63 of the adjusting wedge 60 presses the insert 40 described later. Thus, the adjustment wedge 60 is attached to the notch 27 of the tool body 20.

  The insert 40 is made of a hard material such as cemented carbide, and has a substantially square plate shape with a certain thickness as shown in FIG. 7 in a plan view, in FIG. 8 in a side view, and in FIG. 9 in a front view. A rectangular rake face 41, 42 and four side faces arranged perpendicular to the two rake faces 41, 42, and the intersecting ridge line portion of these four side faces is a rake face. A portion that intersects 41 and 42 is a corner portion 48.

  Of these four side surfaces, either one of the side surfaces 43 and 44 orthogonal to the long sides of the rake surfaces 41 and 42 is a contacted surface with which the mounting seat 26b of the insert mounting portion 26 of the tool body 20 is contacted. An insert mounting screw insertion hole 45 is formed so that these two side surfaces 43 and 44 communicate with each other.

  Of the four side surfaces of the insert, either one of the side surfaces 46 and 47 orthogonal to the short sides of the rake surfaces 41 and 42 is pressed against the pressing surface 63 of the adjusting wedge 60 described above. The pressing surface.

  The two rake faces 41 and 42 are provided with breaker grooves 49 that extend toward the inside of each corner portion 48 and are recessed from the rake faces 41 and 42. As shown in FIGS. 8 to 10, the breaker groove 49 includes an inclined surface 49 a extending so as to gradually retreat from the rake surfaces 41 and 42 in which the breaker groove 49 is formed, as the distance from the corner portion 48 increases. A concave curved surface 49b connecting the surface 49a and the rake surfaces 41 and 42 is provided.

  Then, as shown in detail in FIG. 11, the corner portion 48 of the insert 40 is chamfered in a flat shape from one rake face 41 to the other rake face 42 as the front and back surfaces. A flat land 51 formed as described above is provided. The flat land 51 is formed such that a straight line l along the surface in plan view is parallel to the axis O when the insert 40 is attached to the tool body 20. Further, between the flat land 51 and the side surfaces 46 and 47 that contact the short sides of the rake surfaces 41 and 42 among the four side surfaces, a convex cylindrical surface that smoothly contacts the flat land 51 and the side surfaces 46 and 47. A rounded surface 52 is formed.

  A cutting edge 53 is formed at the intersection ridge line portion of the flat land 51 and the rounded surface 52 and the inclined surface 49 a of the breaker groove 49. Therefore, in this insert 40, the cutting edge 53 is provided in the corner part 48, respectively, and the breaker groove | channel 49 is arrange | positioned so that it may go inside the rake surfaces 41 and 42 from these cutting edges 53. FIG. The portions of the rake surfaces 41, 42 other than the breaker groove 49 are flat surfaces that do not retreat more than the cutting blade 53, that is, protrude from the cutting blade 53 or are disposed at the same height. Has been.

  In this embodiment, as shown in detail in FIGS. 3 and 4, the insert 40 having such a configuration is provided with one of the two rake surfaces 41, 42, one of which is a contacted surface. Insert mounting is performed such that one side 43 of the side surfaces 43, 44 that are in contact with the contact surface 26 a of the portion 26 and are orthogonal to the long sides of the rake surfaces 41, 42 contacts the mounting seat 26 b of the insert mounting portion 26. An insert mounting screw 55 is inserted into the screw insertion hole 45 and the insert 40 is fixed to the tool body 20.

  As a result, the insert 40 is attached to the tool body 20 at an inclination by the mounting seat 26b, and the straight line 1 of the flat land 51 of the insert 40 and the axis O of the tool body 20 are parallel, that is, the cutting edge of the insert 40. The tip of 53 and the axis O of the tool body 20 are arranged in parallel.

  Further, as described above, the adjustment wedge 60 is inserted into the tool rear end side of the insert 40 fixed to the tool body 20 as described above, and as shown in FIG. 3 or FIG. It will be in the state contact | adhered to the side surface 47 of the insert 40. FIG.

  In the boring bar 10 configured as described above, the tool body 20 is attached to the main end shaft of the machine tool via an adapter or the like, and is rotated at high speed in the tool rotation direction T around the axis O of the tool body 20. The tool body 20 is fed to the tip end side in the axis O direction, inserted into a prepared hole provided in advance in the workpiece, and the inside of the prepared hole is formed by the cutting blade 53 of the insert 40 provided at the tip portion of the tool body 20. The wall surface is cut to form a processed hole having a predetermined inner diameter.

  According to the boring bar 10 of the present embodiment, the flat land 51 is formed on the insert 40, and the cutting edge 53 formed on the intersecting ridge line between the flat land 51 and the rake face 41, 42 of the insert. The tip is also linear when viewed from the tool rotation direction T side. Since this insert 40 is attached to the tool body 20 so that the straight line 1 formed by the flat land 51 is parallel to the axis O of the tool body 20, the inside of the prepared hole of the workpiece is cut during the cutting process. The surface of the wall surface and the tip of the cutting edge 53 are parallel to each other.

  Therefore, by increasing the contact length between the cutting edge 53 and the inner wall surface of the pilot hole, and cutting along the surface shape of the inner wall surface, the inner wall surface is cylindrical with the axis O as the center. It is possible to improve the surface roughness of the processed hole.

  Moreover, when setting the amount of protrusion of the cutting edge 53 in the tool radial direction to be suitable for the prepared hole to be machined, or the tool diameter of the cutting edges 53 of the plurality of inserts 40 arranged at equal intervals in the circumferential direction. When equalizing the position of the direction, the insert 40 is pressed to the tool tip side and the tool body radial direction outside by adjusting the insertion amount of the adjustment wedge 60. As a result, the position of the cutting edge 53 in the tool radial direction can be adjusted while the flat land 51 is maintained parallel to the axis O.

  Further, when the insert 40 is pressed in the direction inclined with respect to the axis O and the amount of protrusion of the cutting blade 53 in the tool radial direction is adjusted, the tool is directly pressed outward in the tool radial direction. In comparison, the amount of movement of the cutting blade in the tool radial direction due to the screwing amount of the adjustment wedge 60 is reduced. Therefore, it is possible to finely adjust the protruding amount of the cutting blade 53.

  Further, in the boring bar of the present embodiment, since the breaker groove 49 is formed as described above, the scraped chips move along the inclined surface 49a and are forcibly bent when reaching the concave curved surface 49b. Therefore, the chips can be cut short to facilitate the processing.

  Moreover, when the rake surfaces 41 and 42 are provided in the two side surfaces located in the mutually opposite side of the insert 40 like this embodiment, when attaching the insert 40, it is turned to the tool rotation direction back side. By bringing the portion of the rake face 42 other than the breaker groove 49 into close contact with the contact surface 26a, the contact area between the insert 40 and the contact surface 26a can be secured. Accordingly, the cutting force acting on the cutting edge 53 can be reliably received by the tool body 20, and the cutting edge 53 can be prevented from being lost and the life of the insert 40 can be extended.

  Further, the round surface 52 between the flat land 51 and the side surfaces 46 and 47 of the insert 40 is formed, so that when the tool body 20 is sent to the tip side in the direction of the axis O, the round surface 52 and the rake surface are formed. Since the convex curvilinear cutting edge 53 formed at the intersecting ridge line with the material first comes into contact with the material to be cut, the concentration of stress during cutting is suppressed, and the corner portion 48 of the insert 40 is damaged. Can be prevented.

  The boring bar 10 as an embodiment of the cutting tool of the present invention has been described above, but the present invention is not limited to this and can be appropriately changed without departing from the technical idea of the present invention.

It is the longitudinal cross-sectional view which fractured | ruptured a part which shows the boring bar which is embodiment of this invention. It is a front view of the boring bar which is an embodiment of the present invention. It is the elements on larger scale of FIG. FIG. 3 is a partially enlarged view of FIG. 2. It is an A direction arrow directional view in FIG. It is BB sectional drawing in FIG. It is a top view of insert. It is a side view of an insert. It is a front view of an insert. It is a C direction arrow directional view in FIG. It is an enlarged view of the part P in FIG.

Explanation of symbols

10 Boring bar (cutting tool)
20 Tool body 27 Notch 40 Insert 41 Rake face 42 Rake face 48 Corner part 49 Breaker groove 51 Flat land 52 Round face 53 Cutting edge 60 Adjusting wedge O Axis line T Tool rotation direction

Claims (4)

An insert having a cutting edge is attached to the outer periphery of the tip of the tool body rotated around the axis, inserted into a prepared hole formed in the workpiece, and the inner wall surface of the prepared hole is cut to obtain a predetermined inner diameter. A cutting tool for forming a machining hole of
The insert has a rectangular flat plate shape, flat surface flat lands intersecting at the tip side of each corner portion of the rake face directed forward in the tool rotation direction, and the flat land and the rake face Cutting edges are formed on each cross ridge line,
A cutting tool, wherein the insert is attached so that any one of the flat lands is positioned on a radially outer periphery of the tool body, and the flat lands are parallel to the axis. The insert is attached so that a side surface facing the radial direction of the tool main body is inclined so as to go outward in the tool radial direction toward the tip end side of the tool main body with respect to the axis.
The adjustment wedge that presses the insert toward the tool body tip side and the tool body radial direction outside in parallel to the side surface is inserted into the tool rear end side of the insert of the tool body. The cutting tool according to 1.   The rake face is formed with a breaker groove that is recessed so as to retreat with respect to the rake face inward from the tip side of each corner portion. The rake face other than the breaker groove is formed by the cutting edge. The cutting tool according to claim 1, wherein the cutting tool is a flat surface that does not recede.   The cutting tool according to any one of claims 1 to 3, wherein an end of the flat land on the tool tip side of the insert is formed in a convex curved surface shape.

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