JP2013056396A - Indexable type thread milling cutter - Google Patents

Abstract

PROBLEM TO BE SOLVED: To mount an indexable chip in a surely abutted state on a pair of wall faces at a chip mounting recess, and to properly maintain the abutted state during screw machining.SOLUTION: When mounting screws 30 and 32 are screwed into a body 12 in a state that the indexable chip 14 is inserted into a chip mounting groove 20 formed at the body 12, a back face 14c of the indexable chip 14 is pressed on a groove side face 20c of the chip mounting groove 20 by the engagement of tapered abutting sections 34 and 44 and tapered recesses 40 and 46 which are provided in the mounting screws 30 and 32, and pressing loads F1 and F2 are applied to the indexable chip 14 by a wedge action by the eccentric engagement of the abutting sections 34 and 44 and the tapered recesses 40 an 46. A bottom face 14a and a shank side end face 14b of the indexable chip 14 are pressed on a groove bottom face 20a and a groove end face 20b of the chip mounting groove 20, respectively.

Description

  The present invention relates to a thread cutting mill, and in particular, an indexable type in which an indexable chip (corresponding to a throwaway chip defined in JIS) provided with a thread cutting blade is detachably mounted on a body by a plurality of mounting screws. The present invention relates to an improvement in thread cutting milling.

  (a) a chip mounting recess provided in the body; and (b) an indexable chip that is detachably mounted in the chip mounting recess and provided with an uneven thread cutting blade; and It is screwed into the body and is brought into contact with the indexable chip from the rake face side of the indexable chip, and the back surface of the indexable chip is pressed against the mounting seat surface of the chip mounting recess. 2. Description of the Related Art Indexable threading milling cutters are known that have mounting screws that are secured together. The thread cutting mill described in Patent Document 1 is an example thereof, and the tip of the mounting screw is brought into contact with a recess provided on the side surface of the indexable tip, thereby pressing the back surface of the indexable tip against the mounting seat surface. In addition, it is pressed against the bottom wall surface of the chip mounting recess by the wedge action to perform radial positioning. Patent Document 2 discloses a case where the mounting screw is threaded into the body through the insertion hole provided in the indexable chip, and the head of the mounting screw and the insertion hole are taper-fitted. The lower surface and the pair of side surfaces of the indexable chip are positioned at predetermined positions in contact with the bottom surface (mounting seat surface) of the chip mounting recess and the pair of wall surfaces, respectively.

Special table 2003-503219 gazette Japanese Patent Laid-Open No. 6-39640

  However, in the case of the cited document 1, since the positioning in the axial direction is merely brought into contact with the wall surface of the chip mounting recess, the wall surface is fixed when the mounting screw is screwed into the body to fix the indexable chip. There is a possibility that the indexable tip may be displaced in the axial direction due to vibration and load during screw machining. In the example of the cited document 2, the indexable tip is positioned with high accuracy by the taper fitting with the mounting screw, and it is suppressed that the indexable tip is displaced at the time of screw processing. There is a possibility that a gap may be formed between the pair of side surfaces and the pair of wall surfaces of the chip mounting recess, or on the contrary, they may interfere with each other and cannot be mounted. If there is a gap between the side surface of the indexable tip and the wall surface of the chip mounting recess, the indexable tip is supported only by the mounting screw, so that rigidity may be insufficient during threading and processing accuracy may be impaired. There is sex.

  The present invention has been made against the background of the above circumstances, and the object of the present invention is to attach the indexable chip in a state in which the indexable chip is securely in contact with the pair of wall surfaces of the chip mounting recess. At the same time, the contact state is appropriately maintained even during screw machining.

  In order to achieve such an object, the first invention comprises (a) a chip mounting recess provided in a body, and (b) a detachable screw cutting blade mounted in the chip mounting recess. An indexable chip provided; and (c) screwed into the body and brought into contact with the indexable chip from the rake face side of the indexable chip. An indexable threaded milling cutter having a mounting screw that is pressed against and fixed to the mounting seating surface of the chip mounting recess, and (d) the mounting screw is brought into contact with the indexable chip The portion of the indexable tip is provided with a taper receiving surface at the same taper angle as that of the contact portion. On the other hand, (e) the chip mounting recess has a pair of positioning wall surfaces in a positional relationship intersecting each other around the mounting seat surface, and the indexable chip is in contact with the pair of positioning wall surfaces (F) a pair of positioning side surfaces of the indexable chip are in contact with the pair of positioning wall surfaces, and the taper center of the contact portion is the taper A pressing load that is eccentric from the taper center of the receiving surface and presses the pair of positioning side surfaces against the pair of positioning wall surfaces by the wedge action due to the eccentric engagement between the contact portion and the taper receiving surface. It is added to the indexable chip.

  According to a second aspect of the present invention, in the indexable threaded milling cutter of the first aspect, a taper angle of the contact portion and the taper receiving surface is in a range of 80 ° to 140 °.

  According to a third aspect of the present invention, in the indexable thread milling cutter of the first or second aspect, the eccentric direction in which the taper center of the contact portion is eccentric from the taper center of the taper receiving surface is from the taper center of the taper receiving surface. It is defined between the perpendiculars to the pair of positioning wall surfaces and within an angle range of 5 ° or more inside each of the perpendiculars.

  A fourth aspect of the invention is the indexable threaded milling cutter according to the first to third aspects of the present invention, wherein the amount of eccentricity in which the taper center of the contact portion is decentered from the taper center of the taper receiving surface is in the range of 0.05 mm to 0.3 mm. It is characterized by being within.

  The fifth invention is the indexable thread milling cutter according to the first to fourth inventions, wherein (a) the chip mounting recess is a chip mounting groove provided in a straight line in the axial direction of the body, and the indexable chip is The chip mounting groove is fitted into the chip mounting groove, and one groove side surface of the chip mounting groove functions as the mounting seat surface, and the groove bottom surface and the groove end surface on the shank side respectively serve as the pair of positioning wall surfaces. While the abutment-side end surface and the bottom surface of the indexable chip functioning as the pair of positioning side surfaces are positioned in contact with each other, (b) the mounting screw is viewed from the screwing side, the chip mounting groove And the abutting portion is provided at the tip of the mounting screw, and (c) the index sub The chip, characterized in that the tapered recess which can accept the tip of the contact portion is provided which has the tapered receiving surface.

  In such an indexable threading milling machine, if the mounting screw is screwed to the body in a state where the indexable chip is disposed in the chip mounting recess provided on the body, the tapered shape provided on the mounting screw is formed. The engagement between the contact portion and the taper receiving surface not only presses the back surface of the indexable chip against the mounting seat surface of the chip mounting recess, but also the eccentric relationship between the contact portion and the taper receiving surface. The pair of positioning side surfaces of the indexable chip are pressed against the pair of positioning wall surfaces of the chip mounting recess by the wedge action. That is, simply by screwing the mounting screw into the body, the indexable tip can be securely attached to the pair of positioning wall surfaces of the chip mounting recess by the wedge action due to the eccentric engagement between the contact portion and the taper receiving surface. Since it can be attached in a contact state, attachment work is facilitated and attachment failure due to dimensional error or the like is suppressed. Also, during threading, the indexable tip abuts against the pair of positioning wall surfaces of the chip mounting recess regardless of vibration or processing load due to the wedge action due to the eccentric engagement between the contact portion and the taper receiving surface. The contact state is appropriately maintained, the indexable tip is held on the body with high rigidity, and positional deviation is suppressed, so that excellent machining accuracy can be obtained.

  In the second invention, since the taper angle of the abutment portion and the taper receiving surface is in the range of 80 ° to 140 °, the pair of positioning side surfaces of the indexable tip are formed by the wedge action due to such eccentric engagement. Each can be reliably pressed against the pair of positioning wall surfaces of the chip mounting recess. In other words, if the taper angle is smaller than 80 °, although the pressing load for pressing the indexable chip against the pair of positioning wall surfaces of the chip mounting recess is increased by the wedge action, sufficient fastening strength cannot be obtained, and the screw While the mounting screw may loosen due to vibration or processing load during processing, if the taper angle exceeds 140 °, the pressing load due to the wedge action will decrease, and the indexable tip may be displaced during screw processing. is there.

  In the third invention, the eccentric direction in which the taper center of the abutting portion is eccentric from the taper center of the taper receiving surface is between each perpendicular line from the taper center of the taper receiving surface to the pair of positioning wall surfaces, and Since each of the pair of positioning side surfaces of the indexable tip is formed by the wedge action due to the eccentric engagement between the contact portion and the taper receiving surface, each of the pair of positioning side surfaces of the indexable tip is formed in the tip mounting recess. It is appropriately pressed against the pair of positioning wall surfaces.

  In the fourth invention, since the amount of eccentricity between the taper center of the contact portion and the taper center of the taper receiving surface is in the range of 0.05 mm to 0.3 mm, the wedge action due to such eccentric engagement causes indexing. The pair of positioning side surfaces of the insertable chip can be reliably pressed against the pair of positioning wall surfaces of the chip mounting recess. That is, if the amount of eccentricity is smaller than 0.05 mm, it varies depending on the taper angle, but there is a slight dimensional error between the pair of positioning side surfaces of the indexable chip and the pair of positioning wall surfaces of the chip mounting recess. On the other hand, if there is a possibility that a gap will occur, if the amount of eccentricity exceeds 0.3 mm, the engagement length between the two will be shortened depending on the size of the abutting part and the taper receiving surface. There is a possibility that the engaging portion is deformed by the processing load and the indexable tip is displaced. If the amount of eccentricity increases, the contact part may come off from the taper receiving surface, and to prevent this, increasing the contact part or taper receiving surface increases the structure size, such as increasing the diameter of the mounting screw. This may not be applicable to small-diameter thread milling cutters.

  The fifth invention is a case where the chip mounting recess is a chip mounting groove provided in a straight line in the axial direction of the body, and the indexable chip is fitted and fixed in the chip mounting groove, and the mounting screw is The contact portion provided at the tip of the mounting screw is eccentrically engaged with the taper receiving surface by being screwed into the body on the front side of the chip mounting groove as viewed from the screwing side. In this case, the screwing portion and the eccentric engagement portion of the mounting screw can be positioned close to each other, so that the mounting screw can be prevented from falling due to the reaction force of the wedge action, and the pressing load due to the wedge action is appropriate. Thus, the indexable chip can be more reliably pressed against the pair of positioning wall surfaces of the chip mounting recess.

BRIEF DESCRIPTION OF THE DRAWINGS It is a figure which shows the indexable thread cutting mill which is one Example of this invention, (a) is a top view, (b) is a front view, (c) is the bottom view seen from the front end side (right side of figure) of (b) FIG. It is an expanded sectional view of the II-II arrow part in (b) of FIG. FIG. 2 is a view independently showing the indexable tip of the indexable threaded milling cutter of FIG. 1, wherein (a) is a plan view, (b) is a front view, (c) is a right side view, and (d) is a perspective view. It is a figure which shows the contact state of a pair of attachment screw with respect to an indexable chip | tip, (a) is a top view, (b) is a front view, (c) is a right view. It is a figure explaining press load F1, F2 which arises by a wedge action when a pair of attachment screws are made to contact a pair of taper crevice provided in an indexable chip, and each is engaged eccentrically. It is a figure explaining the processing method of the internal thread by the indexable type threading milling cutter of FIG. Explained the results of investigating the relationship with the pressing performance due to the wedge action of various specifications related to the eccentric engagement between the tapered contact portion provided on the mounting screw and the tapered recess provided on the indexable tip. It is a figure to do. FIG. 5 is a perspective view showing an embodiment in which the present invention is applied to a two-blade indexable thread milling cutter in which a pair of indexable tips are provided symmetrically with respect to an axis O. FIG. 2 is a diagram showing an embodiment in which the present invention is applied to a three-blade indexable threading milling cutter in which three indexable tips are arranged around an axis O, (a) is a front view, and (b) is ( The bottom view seen from the front end side (right side of the figure) of a), and (c) is a perspective view. FIG. 2 is a diagram showing an embodiment in which the present invention is applied to a five-blade indexable thread milling cutter in which five indexable tips are arranged around an axis O, (a) is a front view, and (b) is ( The bottom view seen from the front end side (right side of the figure) of a), and (c) is a perspective view. 10A and 10B are diagrams showing contact states of mounting screws with respect to five indexable tips, where FIG. 10A is an end view seen from the shank side, and FIG. 10B is a front view seen from the right side of FIG. FIG. FIG. 5 is a view showing still another embodiment of the present invention, and (a) and (b) are both cross-sectional views perpendicular to the axis O corresponding to FIG.

  The indexable threading milling machine of the present invention is driven by an NC machining center or the like so as to be rotated around an axis and reciprocated relative to a screw material (workpiece) in the axial direction. Various screws and female screws having different diameters can be cut using a single tool. The internal thread cutting may be a bottomed blind hole or a through hole.

  In addition, only the thread groove is cut by the convex part of the thread cutting blade, and the inner peripheral surface of the pilot hole forms the peak of the female thread, or the outer peripheral surface of the cylindrical material is the peak of the male thread. However, the concave portion between the convex portions may also contribute to the cutting process, and may have a total cutting edge that performs the cutting process including the top of the screw thread.

  The thread cutting blade may be a straight blade (straight blade) parallel to the axis of the body, a twisted blade twisted around the axis, or an inclined blade inclined at a constant angle with respect to the axis. The shape of the indexable tip is appropriately determined according to the shape of the thread cutting blade. The chip mounting recess is constituted by a chip mounting groove provided in a straight line in an axial direction parallel to the axis or inclined at a predetermined angle as in the fifth invention, for example. However, as described in Patent Document 2, the index mounting recess is indexed. A concave chip mounting seat or the like that holds the rake face side of the sable chip exposed may be used.

  Both the abutment portion of the mounting screw and the taper receiving surface have a tapered shape (conical shape) having the same taper angle, but it is not always necessary to provide the top of the taper and is usually a truncated cone shape. In addition, the entire circumference of the contact portion of the mounting screw that is rotated about the axis is tapered, but at least the linear portion with which the contact portion is engaged is the contact portion. It suffices that they are provided with the same inclination, and a part of the tapered shape may be cut out. In a state where the indexable chip is attached to the body, the abutting portions and the center lines of the taper receiving surfaces are parallel to each other and are engaged with each other while being eccentric by a predetermined amount of eccentricity.

  The taper angles of the contact portion and the taper receiving surface do not necessarily have to be exactly the same geometrically, and may be slightly different due to a processing error or the like. In addition, even if the taper angles are slightly different, contact is made over a predetermined length by elastic deformation, local deformation is suppressed, and a pressing load due to eccentric engagement can be obtained appropriately. And an error of about ± 3 ° or less for both the taper receiving surface and about ± 6 ° or less for both are acceptable. This allowable range varies depending on the material, the diameter size, and the like.

  The chip mounting recess is provided with a pair of positioning wall surfaces in a positional relationship intersecting each other around the mounting seat surface. For example, the pair of positioning wall surfaces are perpendicular to the mounting seat surface and the axis of the body. It is constituted by a parallel axial wall surface and a radial wall surface perpendicular to the mounting seat surface and perpendicular to the axis of the body. These axial wall surfaces and radial wall surfaces are flat surfaces and are in a positional relationship intersecting each other at right angles. The pair of positioning wall surfaces may be in contact with each other, but may be provided apart from each other. Further, the wall surface of the chip mounting recess can be used as a positioning wall surface as it is, but the positioning wall surface can also be provided on a protruding portion or the like that partially protrudes inward from the wall surface.

  The indexable chip includes a pair of positioning side surfaces that are brought into contact with the pair of positioning wall surfaces, and these positioning side surfaces are preferably brought into surface contact with a flat surface parallel to the positioning wall surface. It suffices if the indexable chip can be positioned by bringing the portion into contact with the positioning wall surface. As the positioning side surface, the side surface of the indexable chip can be used as it is, but the positioning side surface can also be provided on a protruding portion or the like partially protruding outward from the side surface.

  The indexable chip can be fixed to the body with a single mounting screw, but can also be fixed to the body using a plurality of mounting screws. In that case, it is only necessary to obtain a pressing load due to the wedge action with respect to at least one mounting screw, but it is also possible to provide a pressing load due to the wedge action with respect to all the attachment screws.

  In the second invention, the taper angle of the contact portion and the taper receiving surface is in the range of 80 ° to 140 °. However, when implementing other inventions, the taper angle can be set beyond the angle range. It is. The direction of eccentricity and the amount of eccentricity can also be determined beyond the scope of the third invention and the fourth invention.

  The fifth invention is a case where the chip mounting recess is a chip mounting groove provided in a straight line in the axial direction of the body, and the indexable chip is fitted and fixed in the chip mounting groove. Screwed into the body on the front side of the chip mounting groove when viewed from the screwing side, and the contact portion provided at the tip of the mounting screw is eccentrically engaged with the taper receiving surface. A mounting screw can be screwed onto the opposite side of the groove. That is, (a) the mounting screw is screwed to the body on the opposite side of the chip mounting groove when viewed from the screwing side, and (b) the front side portion of the body is closer to the chip mounting groove. An insertion hole having a diameter larger than that of the head of the mounting screw is provided, and a through hole having a diameter smaller than that of the head is provided in the indexable tip, and the head contacts the peripheral edge of the opening of the through hole. The indexable tip is pressed against the side surface of the one groove by being contacted, and (c) the contact portion is provided on the head and the opening peripheral portion of the through hole is provided. It is comprised so that the said taper receiving surface may be provided. In this case, since the indexable tip is interposed between the screwed portion and the eccentric engagement portion of the mounting screw, the mounting screw may fall down due to the reaction force of the wedge action. Since it is located in the insertion hole provided in the body, the play between the insertion hole and the head is appropriately set to suppress the fall of the mounting screw, and the pressing load due to the wedge action can be obtained appropriately. Can be.

  The indexable tip is composed of a hard tool material such as high-speed tool steel or cemented carbide, for example. If necessary, a compound coating such as TiN, TiCN, TiAlN, CrN or DLC (Diamond Like Carbon; diamond) Or a hard coating such as a diamond coating, or a water vapor treatment or a nitriding treatment. As the body, a relatively inexpensive tool material such as tool steel is used.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
FIG. 1 is a view showing an indexable threading milling cutter 10 (hereinafter simply referred to as a threading milling cutter 10) according to an embodiment of the present invention, where (a) is a plan view viewed from a direction perpendicular to the axis O, and (b). (A) is a front view seen from below, (c) is a bottom view seen from the tip side (right side of the figure) of (b). FIG. 2 is an enlarged cross-sectional view taken along the line II-II in FIG. 3 is a view independently showing the indexable tip 14 of the threaded milling cutter 10 of FIG. 1, wherein (a) is a plan view, (b) is a front view, (c) is a right side view, (d) (B) is a perspective view seen from diagonally upward on the right side of FIG.

  The thread milling cutter 10 is used by integrally fixing an indexable tip 14 to a body 12, and the body 12 includes a large-diameter cylindrical shank 16 held by a main shaft such as a machining center, A small-diameter cylindrical tip mounting portion 18 to which the dextable tip 14 is attached is integrally provided concentrically in the axial direction. On the outer peripheral surface of the chip mounting portion 18, there is provided a chip mounting groove 20 having a constant width and a rectangular cross section (right-angled quadrilateral) so as to be inclined with respect to the axis O at a predetermined inclination angle θ. The indexable chip 14 having a certain width and a straight longitudinal plate shape is detachably fitted into the chip mounting groove 20 so as to be integrally fixed. The portion where the indexable chip 14 is fitted into the chip mounting groove 20 has a rectangular cross section like the chip mounting groove 20 and is inserted so as to be movable in the axial direction and the radial direction of the body 12. The inclination angle θ is set to a constant angle within a range of 0 ° <θ ≦ 20 °, for example. The tip mounting groove 20 opens at the tip of the tool, and one end of the indexable tip 14 protrudes slightly from the body 12 toward the tip.

  The indexable tip 14 is provided with a large number of ridges at regular intervals in the longitudinal direction, and a concavo-convex thread cutting blade 22 is formed along one end edge of the ridges. The thread cutting blade 22 is a right-twisted twist blade whose twist angle is a constant angle within a range of, for example, about 3 ° to 23 ° in a state where the indexable tip 14 is mounted in the chip mounting groove 20. A rake face 24 is provided along 22, and cutting is performed by being rotated clockwise around the axis O as viewed from the shank 16 side. The present embodiment relates to a small-diameter threading milling cutter whose outer diameter is within a range of 10 mm to 23 mm and whose pitch is within a range of 0.5 mm to 3 mm. The present invention can also be applied. The indexable chip 14 is made of a cemented carbide and is coated with a hard coating such as TiN, TiCN, TiAlN, or CrN as necessary. The body 12 is made of a relatively inexpensive tool material such as high-speed tool steel.

  The indexable chip 14 is integrally fixed to the chip mounting part 18 by a pair of mounting screws 30 and 32 at a pair of screwing points spaced apart in the axial direction of the chip mounting part 18. Yes. The mounting screws 30 and 32 are screwed into the chip mounting portion 18 from the side that intersects the chip mounting groove 20 at a substantially right angle and faces the cutting rotation direction, that is, the rake face 24 side of the indexable chip 14. The back surface 14c of the indexable chip 14 is pressed to one groove side surface 20c of the chip mounting groove 20, that is, the opposite side as viewed from the screwing side of the mounting screws 30 and 32 (the right groove side surface in FIG. 1 (c)). Fix together. Both the back surface 14c and the groove side surface 20c are flat surfaces, and are pressed so as to be in surface contact with each other to be frictionally engaged. Thus, in FIG. 1C, when cutting is performed by being rotated counterclockwise about the axis O, the direction of the cutting force applied to the indexable tip 14 (clockwise direction) and the mounting screw 30 , 32 coincides with the direction pressed by the mounting screws 30, 32, and the fixed state by the mounting screws 30, 32 is maintained satisfactorily regardless of the cutting resistance, and rattling or displacement of the indexable tip 14 is suppressed. The chip mounting groove 20 corresponds to a chip mounting recess, and the groove side surface 20c corresponds to a mounting seat surface.

  The manner in which the mounting screws 30 and 32 are screwed into the chip mounting portion 18 and the manner in which the mounting screws 30 and 32 abut on the indexable chip 14 are basically the same, and are configured as shown in FIG. FIG. 2 relates to the mounting screw 30. Specifically, the mounting screw 30 is screwed into the chip mounting portion 18 on the front side of the chip mounting groove 20 without penetrating the indexable chip 14, and is concentrically integrated with the tip portion. The abutting portion 34 provided on the indexable tip 14 is brought into contact with the front surface 14f of the indexable tip 14 and presses the indexable tip 14 against the groove side surface 20c. A screw hole 38 is provided in a portion on the front side of the chip mounting groove 18 of the chip mounting portion 18 (a portion on the left side of the chip mounting groove 20 in FIG. 2), and the mounting screw 30 is screwed, while the abutting portion 34. Has a truncated tapered shape, and a front surface 14f of the indexable chip 14 is provided with a bottomed tapered recess 40 at substantially the same taper angle as the contact portion 34. The attachment position of the indexable tip 14 with respect to the tip mounting portion 18 is defined by the engagement between the tip 34 and the tapered recess 40. The taper angles of the contact portion 34 and the tapered recess 40 are determined within a range of 80 ° to 140 °, for example, within a range of about 90 ° to 130 °. The tapered inner wall surface of the tapered recess 40 corresponds to a taper receiving surface, and a relief hole is provided at the bottom of the tapered recess 40 so that the tip of the contact portion 34 can be received.

  The abutting portion 34 and the tapered recess 40 are in a mounting state in which the indexable tip 14 is attached to the tip mounting groove 20, that is, the bottom surface 14a of the indexable tip 14 and the shank side end surface 14b are grooves of the tip mounting groove 20, respectively. In a state where the bottom surface 20a and the groove end surface 20b on the shank 16 side are in contact with each other, the taper center lines of both are parallel to each other and the taper center S1 of the contact portion 34 is the taper center T1 of the taper recess 40. The bottom surface 14a of the indexable tip 14 and the shank side end surface 14b are pressed against the groove bottom surface 20a of the tip mounting groove 20 and the groove end surface 20b on the shank 16 side, respectively, by the wedge action due to the eccentric engagement. A pressing load F1 is applied to the indexable tip 14. That is, as shown in FIG. 5, the taper center S1 of the abutting portion 34 is predetermined from the direction toward the shank 16 parallel to the axis O by a predetermined eccentric amount G1 with respect to the taper center T1 of the tapered recess 40. When the mounting screw 30 is tightened in the screw hole 38 in this state, the taper contact portion 34 and the taper recess 40 are eccentrically engaged with each other. Thus, the pressing load F1 is applied to the indexable chip 14. The eccentric amount G1 is set in the range of 0.05 mm to 0.3 mm, for example, in the range of about 0.1 mm to 0.25 mm, and the inclination angle α1 is in the range of 5 ° to 85 °, for example, 30 ° to It is set within a range of about 60 °. The perpendicular from the taper center T1 to the groove end surface 20b is an inclination angle α1≈0 °, the perpendicular from the taper center T1 to the groove bottom surface 20a is the inclination angle α1≈90 °, and the inclination angle α1 is between these perpendiculars. And at least 5 ° or more inward. In other words, the position of the screw hole 38 into which the mounting screw 30 is screwed is determined so that the contact portion 34 is engaged with the tapered recess 40 in the predetermined eccentric state. Since the taper angles of the abutment portion 34 and the taper recess 40 are substantially the same, the taper surfaces are substantially line-contacted in the axial direction by the eccentric engagement of both (strictly speaking, surface contact with a predetermined width by elastic deformation). It is done.

  FIG. 4 is a diagram showing an eccentric engagement state of the mounting screw 30 with respect to the tapered recess 40 of the indexable tip 14, and also shows the other mounting screw 32. That is, the mounting screw 32 is also provided with a tapered contact portion 44 concentrically in the same manner as the mounting screw 30 and is screwed into the screw hole 42 (see FIG. 1 (a)). As shown in FIG. 5, the bottom surface 14 a and the shank side end surface of the indexable tip 14 are made eccentrically engaged with a tapered recess 46 provided on the front surface 14 f of the indexable tip 14, similar to the mounting screw 30. A pressing load F <b> 2 is applied to the indexable chip 14 for pressing 14 b against the groove bottom surface 20 a of the chip mounting groove 20 and the groove end surface 20 b on the shank 16 side. In FIG. 5, T <b> 2 is the taper center of the tapered recess 46, and S <b> 2 is the taper center of the contact portion 44. The taper angles of the contact portion 44 and the taper recess 46 are also set within the range of 80 ° to 140 ° and substantially the same angle within the range of about 90 ° to 130 °, similarly to the mounting screw 30 side. The eccentric amount G2 and the inclination angle α2 are also set to the same size as the eccentric amount G1 and the inclination angle α1 on the mounting screw 30 side.

  In this embodiment, the bottom surface 14a and the shank side end surface 14b of the indexable chip 14 correspond to a pair of positioning side surfaces, and the groove bottom surface 20a and the groove end surface 20b of the chip mounting groove 20 correspond to a pair of positioning wall surfaces. The groove bottom surface 20a and the groove end surface 20b are provided around the groove side surface 20c, which is a mounting seat surface, so as to cross each other at a right angle, and the groove bottom surface 20a is perpendicular to the groove side surface 20c and the body 12 The groove end surface 20b is perpendicular to the groove side surface 20c and is perpendicular to the axis O of the body 12 at a flat radial wall surface. Position the direction. The bottom surface 14a and the shank side end surface 14b of the indexable chip 14 are also formed as flat surfaces that intersect with each other at right angles and at right angles to the back surface 14c, and the body 12 remains in surface contact with the groove bottom surface 20a. The shank side end face 14b can be slid in the groove depth direction of the chip mounting groove 20 perpendicular to the axis O of the body 12 while being in surface contact with the groove end face 20b.

  FIG. 6 is a diagram for explaining a machining method when the internal thread 62 is cut on a predetermined workpiece 60 by using the thread cutting mill 10 according to the present embodiment. An insertable pilot hole 64 is provided in advance. Then, the thread cutting mill 10 is mounted on an NC machining center or the like and inserted into the pilot hole 64, and is driven to rotate around the axis O as indicated by an arrow A, and the inner part of the pilot hole 64 is indicated by an arrow B. The female thread 62 is cut by the thread cutting blade 22 by being lead-feeded in the axial direction while revolving along the peripheral surface.

  Here, according to the thread cutting mill 10 of this embodiment, if the mounting screws 30 and 32 are screwed into the body 12 in a state where the indexable chip 14 is inserted into the chip mounting groove 20 provided in the body 12, The back surface 14 c of the indexable chip 14 is pressed against the groove side surface 20 c of the chip mounting groove 20 by the engagement between the tapered contact portions 34, 44 provided on the mounting screws 30, 32 and the tapered recesses 40, 46. In addition, the pressing loads F1 and F2 are applied to the indexable tip 14 by the wedge action due to the eccentric engagement between the contact portions 34 and 44 and the tapered recesses 40 and 46, and the indexable tip 14 14 are pressed against the groove bottom surface 20a and the groove end surface 20b of the chip mounting groove 20, respectively. In other words, the indexable tip can be obtained simply by screwing the mounting screws 30 and 32 into the screw holes 38 and 42 of the body 12 and by the wedge action due to the eccentric engagement between the contact portions 34 and 44 and the tapered recesses 40 and 46. 14 can be mounted in a state where it is securely abutted against the groove bottom surface 20a and the groove end surface 20b of the chip mounting groove 20, and the mounting operation is facilitated and mounting defects due to dimensional errors and the like are suppressed. . In addition, even during threading as shown in FIG. 6 and the like, the indexable tip 14 can be inserted into the tip mounting groove regardless of vibration or processing load by the wedge action due to the eccentric engagement between the contact portions 34 and 44 and the tapered recesses 40 and 46. The abutting state in contact with the groove bottom surface 20a and the groove end surface 20b is appropriately maintained, the indexable tip 14 is held by the body 12 with high rigidity, and positional deviation is suppressed, and excellent machining accuracy is obtained. .

  In the present embodiment, the taper angles of the contact portions 34 and 44 and the tapered recesses 40 and 46 are in the range of 80 ° to 140 °. The bottom surface 14a and the shank side end surface 14b of the chip 14 can be reliably pressed against the groove bottom surface 20a and the groove end surface 20b of the chip mounting groove 20, respectively. That is, when the taper angle is smaller than 80 °, sufficient pressing loads F1 and F2 for pressing the indexable chip 14 against the groove bottom surface 20a and the groove end surface 20b of the chip mounting groove 20 by the wedge action are sufficiently fastened. While the strength cannot be obtained and the mounting screws 30 and 32 may loosen due to vibration or processing load during screw processing, when the taper angle exceeds 140 °, the pressing loads F1 and F2 due to the wedge action decrease, and the screw There is a possibility that the indexable tip 14 is displaced during processing.

  In this embodiment, the taper centers S1 and S2 of the contact portions 34 and 44 are eccentric from the taper centers T1 and T2 of the taper recesses 40 and 46, that is, the inclination angles α1 and α2 are the taper centers T1 and T2. Between the perpendiculars to the groove bottom surface 20a and the groove end face 20b and within an angle range of 5 ° to 85 ° which is 5 ° or more inside each perpendicular line, the contact portions 34, 44 Both the bottom surface 14a and the shank side end surface 14b of the indexable tip 14 are appropriately pressed against the groove bottom surface 20a and the groove end surface 20b of the chip mounting groove 20, respectively, by the wedge action due to the eccentric engagement between the taper recesses 40 and 46. Is done.

  In this embodiment, the eccentric amounts G1 and G2 between the taper centers T1 and T2 of the contact portions 34 and 44 and the taper centers S1 and S2 of the taper recesses 40 and 46 are within a range of 0.05 mm to 0.3 mm. Therefore, it is possible to reliably press the bottom surface 14a and the shank side end surface 14b of the indexable tip 14 against the groove bottom surface 20a and the groove end surface 20b of the chip mounting groove 20, respectively, by the wedge action due to such eccentric engagement. it can. That is, when the eccentric amounts G1 and G2 are smaller than 0.05 mm, although depending on the taper angle, the bottom surface 14a of the indexable tip 14, the shank side end surface 14b, and the groove of the tip mounting groove 20 due to a slight dimensional error or the like. While there is a possibility that a gap is generated between the bottom surface 20a and the groove end surface 20b, when the eccentric amounts G1 and G2 exceed 0.3 mm, they also differ depending on the sizes of the contact portions 34 and 44 and the tapered concave portions 40 and 46. However, there is a possibility that the engagement length between the two becomes short, and the engaging portion is deformed by vibration or processing load at the time of threading and the indexable tip 14 is displaced. When the eccentric amounts G1 and G2 are increased, the contact portions 34 and 44 may be detached from the tapered recesses 40 and 46. To prevent this, if the contact portions 34 and 44 and the taper recesses 40 and 46 are enlarged, There is a possibility that the structure becomes large, for example, by increasing the diameter of the mounting screws 30 and 32, and may not be applicable to the small-diameter thread milling cutter 10.

  Further, in this embodiment, the chip mounting groove 20 is provided in a straight line in the axial direction of the body 12 as the chip mounting recess, and the indexable chip 14 is fitted and fixed in the chip mounting groove 20. The mounting screws 30 and 32 are screwed into the body 12 on the front side of the chip mounting groove 20 as viewed from the screwing side, and the contact portions 34 and 44 provided at the tips of the mounting screws 30 and 32 are tapered recesses 40 and 44, respectively. 46 is eccentrically engaged. In this case, since the screwed portions and the eccentric engaging portions of the mounting screws 30 and 32 are located close to each other, the tilting of the mounting screws 30 and 32 due to the reaction force of the wedge action is suppressed, and the wedge action Thus, the pressing loads F1 and F2 can be appropriately obtained, and the indexable chip 14 can be more reliably pressed against the groove bottom surface 20a and the groove end surface 20b of the chip mounting groove 20.

  Incidentally, the taper angles of the contact portions 34 and 44 and the taper recesses 40 and 46, the eccentric amounts G1 and G2, and the eccentric directions (inclination angles α1 and α2) of the taper centers S1 and S2 with respect to the taper centers T1 and T2 are variously changed. When the mounting state when the indexable chip 14 was attached to the body 12 and the chip mounting state after threading were examined, the results shown in FIGS. 7A and 7B were obtained. FIG. 7A shows a case where the inclination angles α1 and α2 are constant at 45 °, the taper angles of the contact portions 34 and 44 and the taper concave portions 40 and 46, and the eccentric amounts G1 and G2 are changed. Is within the range of 80 ° to 140 ° and the eccentric amounts G1 and G2 are within the range of 0.05 mm to 0.3 mm, the indexable tip 14 is inserted into the tip mounting groove both when the tip is attached and after threading. 20 was appropriately brought into contact with both the groove bottom surface 20a and the groove end surface 20b. On the other hand, when the taper angle is 60 ° and the eccentric amounts G1 and G2 are 0 mm, a gap is generated between the indexable chip 14 and the groove bottom surface 20a or the groove end surface 20b of the chip mounting groove 20 when the chip is mounted. . When the taper angle was 60 ° and the eccentric amounts G1 and G2 were 0.1 mm, one of the pair of mounting screws 30 and 32 was loosened after threading. In addition, when the taper angle is 140 ° and the eccentric amounts G1 and G2 are 0.4 mm, or when the taper angle is 160 ° and the eccentric amounts G1 and G2 are 0.3 mm to 0.4 mm, they are indexable after threading. The chip 14 was slightly displaced, and a gap was generated between the groove bottom surface 20a or the groove end surface 20b of the chip mounting groove 20.

  In FIG. 7B, the taper angles of the contact portions 34 and 44 and the taper concave portions 40 and 46 are 90 °, the eccentric amounts G1 and G2 are 0.1 mm, and the eccentric directions, that is, the inclination angles α1 and α2 are changed. If the inclination angles α1 and α2 are in the range of 5 ° to 85 °, both radial and axial tightening (pressing force) is sufficient, both when the chip is mounted and after threading. In addition, the indexable chip 14 was appropriately brought into contact with both the groove bottom surface 20a and the groove end surface 20b of the chip mounting groove 20. On the other hand, when the inclination angles α1 and α2 are 0 °, the axial tightening is sufficient but the radial tightening is insufficient, and the groove between the indexable chip 14 and the chip mounting groove 20 at the time of chip mounting. A gap was formed between the bottom surface 20a. Further, when the inclination angles α1 and α2 are 90 °, the radial tightening is sufficient but the axial tightening is insufficient, and the indexable chip 14 and the groove end surface 20b of the chip mounting groove 20 at the time of chip mounting. There was a gap between them.

  Next, another embodiment of the present invention will be described. In the following embodiments, parts that are substantially the same as those in the above embodiments are denoted by the same reference numerals, and detailed description thereof is omitted.

  The indexable threading mill 70 shown in FIG. 8 is a two-blade threading milling machine, and a pair of chip mounting grooves 20 are provided symmetrically with respect to the axis O in the chip mounting portion 18 of the body 12. A sable chip 14 is attached. These indexable chips 14 are fixed to the body 12 using a pair of mounting screws 30 and 32, respectively, as in the previous embodiment. The relative size of the pair of indexable chips 14 with respect to the body 12 is smaller than that of the above-described embodiment, for example, for a threaded milling cutter having an outer diameter of more than 23 mm. It can be arranged without interfering with each other. FIG. 8 is a perspective view seen from the tip side.

  The indexable threading mill 80 shown in FIG. 9 is a three-blade threading mill, and the chip mounting portion 18 of the body 12 is provided with three chip mounting grooves 20 around the axis O at equal intervals. The indexable tip 14 is attached using a pair of attachment screws 30 and 32 in the same manner as in the above embodiment. Also in this case, the relative size of the three indexable chips 14 with respect to the body 12 is smaller than that of the above-described embodiment, for example, for a threaded milling cutter having an outer diameter of more than 23 mm, and arranged without interfering with each other. It is configured so that it can be installed. 9A is a front view, FIG. 9B is a bottom view seen from the front end side (right side of FIG. 9), and FIG. 9C is a perspective view.

  The indexable threading mill 90 shown in FIGS. 10 and 11 is a five-blade threading mill, and the chip mounting portion 18 of the body 12 is provided with five chip mounting grooves 20 around the axis O at equal intervals. Each of the indexable chips 14 is attached in the same manner as in the above embodiment using a pair of attachment screws 30 and 32. In this case as well, the relative size of the five indexable chips 14 with respect to the body 12 is smaller than that of the above embodiment, and is applied to, for example, a threaded milling cutter having an outer diameter of more than 23 mm. 10A is a front view, FIG. 10B is a bottom view seen from the front end side (right side of the figure), and FIG. 10C is a perspective view. FIG. 11 is a view showing a contact state of the mounting screws 30 and 32 with respect to the five indexable chips 14, wherein (a) is an end view seen from the shank 16 side, and (b) is a right side of (a). It is the front view seen from. As is apparent from FIG. 11, in this embodiment, the mounting screw 30 is screwed in, that is, the screw hole 38 so that the mounting screw 30 can be screwed into the screw hole 38 without interfering with other indexable chips 14. Is inclined with respect to the front surface 14f. In this case, the tapered recess 40 with which the abutting portion 34 of the mounting screw 30 is abutted is also inclined with respect to the front surface 14 f so that the taper center line thereof is parallel to the tapered center line of the abutting portion 34. Provided.

  12 is a cross-sectional view perpendicular to the axis O corresponding to FIG. 2. In the embodiment of FIG. 12A, the mounting screw 100 is inserted through the indexable tip 14, and the tip is viewed from the screwing side. By being screwed onto the tip mounting portion 18 on the opposite side across the mounting groove 20, the tapered contact portion 106 provided on the head portion 104 is brought into contact with the indexable tip 14, and the inset The dextable tip 14 is pressed against the groove side surface 20c. A screw hole 108 is provided in a portion opposite to the tip mounting groove 20 as viewed from the screwing side of the mounting screw 100 (on the right side of the tip mounting groove 20 in FIG. 12A), and the screw shaft 110 of the mounting screw 100 is provided. Is inserted into the insertion hole 112 having a diameter larger than that of the head 104 of the mounting screw 100 in a portion on the front side of the tip mounting groove 20 (a portion on the left side of the chip mounting groove 20 in FIG. 12A). , And the head 104 is allowed to be inserted into the insertion hole 112 and come into contact with the indexable tip 14. The indexable tip 14 is provided with a through hole 114 having a diameter smaller than that of the head 104 and larger than that of the screw shaft 110, and abuts on an opening peripheral portion on the side where the screw shaft 110 is inserted. A taper receiving surface 116 is provided at substantially the same taper angle as the portion 106.

  The taper center of the contact portion 106 is eccentric with respect to the taper center of the taper receiving surface 116 in the same manner as in the above-described embodiment, and the indexable tip 14 is attached to the tip by a wedge action due to such eccentric engagement. The groove 20 is attached in a pressed state to the groove bottom surface 20a and the groove end surface 20b. Thereby, the same effect as the said Example is obtained. In this case, since the indexable tip 14 is interposed between the threaded portion and the eccentric engagement portion of the mounting screw 100, the mounting screw 100 may fall down due to the reaction force of the wedge action. Since the head portion 104 of the 100 is located in the insertion hole 112 provided in the chip mounting portion 18, the mounting screw 100 can be tilted by appropriately setting the play between the insertion hole 112 and the head portion 104. And the pressing loads F1 and F2 due to the wedge action can be appropriately obtained.

  As shown in FIG. 12 (b), the groove bottom surface 20a of the chip mounting groove 20 is extended to the outer peripheral surface of the chip mounting portion 18, and the front surface 14f of the indexable chip 14 is mounted so as to be exposed to the outside. It is also possible to employ a chip mounting recess 120.

  As mentioned above, although the Example of this invention was described in detail based on drawing, these are one Embodiment to the last, This invention is implemented in the aspect which added the various change and improvement based on the knowledge of those skilled in the art. be able to.

  10, 70, 80, 90: Indexable threading miller 12: Body 14: Indexable tip 14a: Bottom surface (positioning side surface) 14b: Shank side end surface (positioning side surface) 14c: Back surface 20: Tip mounting groove (chip mounting recess) 20a: groove bottom surface (positioning wall surface) 20b: groove end surface (positioning wall surface) 20c: groove side surface (mounting seat surface) 22: screw cutting blade 24: rake face 30, 32, 100: mounting screw 34, 44, 106: contact Portions 40, 46: Tapered recess (taper receiving surface) 116: Tapered receiving surface 120: Tip mounting recess F1, F2: Press load G1, G2: Eccentricity α1, α2: Inclination angle (eccentric direction) T1, T2: Tapered Tapered center of the recess (taper center of the taper receiving surface) S1, S2: Tape of the contact portion Heart

Claims (5)

A chip mounting recess provided on the body;
An indexable chip that is detachably mounted in the chip mounting recess and provided with an uneven thread cutting blade;
The indexable chip is screwed into the body and is brought into contact with the indexable chip from the rake face side of the indexable chip, and the back surface of the indexable chip is pressed against the mounting seat surface of the chip mounting recess. Mounting screws that are fixed together,
In an indexable threading milling machine having
The mounting screw has a tapered contact portion that contacts the indexable chip, and the same contact portion of the indexable chip where the corresponding contact portion contacts. While the taper receiving surface is provided at the taper angle,
The chip mounting recess has a pair of positioning wall surfaces in a positional relationship crossing each other around the mounting seat surface, and the indexable chip is a pair of positioning side surfaces that are brought into contact with the pair of positioning wall surfaces With
In a mounted state in which the pair of positioning side surfaces of the indexable chip are in contact with the pair of positioning wall surfaces, the taper center of the contact portion is decentered from the taper center of the taper receiving surface, An indexable threading, wherein a pressing load that presses the pair of positioning side surfaces against the pair of positioning wall surfaces is applied to the indexable tip by a wedge action by eccentric engagement with the taper receiving surface. fries. The indexable thread milling machine according to claim 1, wherein a taper angle of the contact portion and the taper receiving surface is in a range of 80 ° to 140 °. The eccentric direction in which the taper center of the contact portion is eccentric from the taper center of the taper receiving surface is between the taper center of the taper receiving surface and each perpendicular to the pair of positioning wall surfaces, and from the perpendicular. The indexable threading miller according to claim 1 or 2, wherein the indexable threading miller is defined within an angle range of 5 ° or more inside. The eccentric amount by which the taper center of the contact portion is decentered from the taper center of the taper receiving surface is in a range of 0.05 mm to 0.3 mm. The indexable threading milling machine described. The chip mounting recess is a chip mounting groove provided in a straight line in the axial direction of the body, and the indexable chip is fitted into the chip mounting groove, and one of the chip mounting grooves The groove side surface functions as the mounting seat surface, the groove bottom surface and the shank side groove end surface each function as the pair of positioning wall surfaces, and the indexable chip bottom surface and the shank side end surface function as the pair of positioning side surfaces. While being positioned in contact with each other,
The mounting screw is screwed to the body on the front side of the chip mounting groove as viewed from the screwing side, and the contact portion is provided at the tip of the mounting screw.
The indexable tip is provided with a tapered recess having the tapered receiving surface and capable of receiving the tip of the contact portion. Indexable threading milling machine.

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