JP2006088308A - Throwaway tip type drill - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a throwaway tip type drill which can improve the life of a body by suppressing the deterioration of the connecting strength by a taper fitting while easily and surely fitting a fitting projection into a fitting recess by means of a slit. <P>SOLUTION: A fitting projection 18 having an inversely tapered portion is provided on the body 10. In addition, the slit 22 is provided on the fitting projection 18 so as to elastically contract its diameter. As a result, the fitting projection 18 can be easily and surely inserted into the fitting recess 20. Further, even when a load has been applied to the fitting projection 18 so as to contract its diameter owing to the cutting resistance and vibrations in drilling, the deformation of the fitting projection 18 is limited within the range of the width of the slit 22 at the maximum. Therefore, the elasticity (a spring force) of the fitting projection 18 due to the slit 22 is excellently maintained, and the deterioration of the connecting strength of the taper fitting is suppressed, and the life of the body 10 is improved. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a throw-away drill, and more particularly to a technique for improving the durability of a body.

  (a) a steel body having a width that is wider than the land and provided with a pair of grooves in the axial direction; and (b) a pair of grooves provided so as to be continuous with the grooves and a tip opening portion of the grooves. A tip tip made of a super hard material having a pair of cutting edges formed thereon, and (c) a reverse tapered shape having a larger diameter toward the tip side, and is concentrically provided on one of the body and the tip tip. And (d) a reverse tapered shape so as to be fitted with the fitting protrusion, and provided concentrically on the other of the body and the tip. And (e) fitting the fitting protrusion with the phase around the axis of the body and the tip of the tip being shifted. Insert into the recess and rotate around the axis By fitting the its fitting projection and the fitting recess by, indexable drills for integrally coupled so as not to escape the distal tip relative to the body by the action of the inverse tapered shape are known. The drill described in Patent Document 1 is an example, and a fitting protrusion is provided on the tip, and is fitted into a fitting recess of the body so as to be coupled. Such a fitting type throw-away type The drill can be favorably applied to a small diameter drill having a drill diameter of about 10 mm or less, for example. Further, in Patent Document 1, a slit is provided at the bottom of a fitting recess provided in the body, and the fitting recess is fitted by fitting the fitting recess elastically. It can be easily and reliably fitted to the recess.

Registered Utility Model No. 3054444

  However, if it is possible to expand by providing a slit at the bottom of the fitting recess in this way, the fitting recess is repeatedly deformed in the expanding direction due to cutting resistance or vibration during drilling, The elasticity (spring force) of the mating recess due to the slit is reduced and tightening is worsened. The coupling strength of the taper mating is lowered in a short period of time, so that the tip tip comes off, and a sufficient body life is achieved. There was a problem that it could not be obtained. That is, it is expected that the throw-away drill can be used for a long period of time while exchanging the tip, but in the experiments by the present inventors, only the tip was replaced about 3 to 5 times. The bond strength decreased and it became unusable.

  The present invention has been made in the background of the above circumstances, and the object of the present invention is to provide a taper while allowing the fitting protrusion to be easily and reliably fitted to the fitting recess by slitting. The object is to improve the body life by suppressing a decrease in the bonding strength due to the fitting.

  In order to achieve such an object, the present invention comprises (a) a steel body provided with a pair of grooves in the axial direction and having a width that is wider than the land, and (b) a pair of steel so as to be continuous with the grooves. A groove tip, and a tip tip made of a carbide material in which a pair of cutting edges are formed at the tip opening portion of the groove, and (c) a reverse taper shape having a larger diameter toward the tip side, The concentric protrusions are concentrically provided on one of the body and the tip, and have a reverse tapered shape so as to be fitted with the fitting protrusions, and (d) the side faces are notched by the grooves. A fitting recess provided concentrically on the other of the body and the tip, and having a side surface cut away by the groove, and (e) a phase around the axis of the body and the tip In a state of being displaced, the fitting protrusion is placed in the fitting recess. By inserting the fitting protrusion and the fitting recess together, the tip of the tip is integrated with the body so that it cannot be pulled out of the body. (F) The fitting projection is provided on the body, and a slit is provided on the fitting projection so that the diameter can be elastically reduced.

  In such a throw-away type drill, the fitting protrusion is provided on the body, and the fitting protrusion is provided with a slit so that the diameter can be elastically reduced. It can be easily and reliably fitted to the fitting recess. In addition, even when a load in the direction of reducing the fitting projection diameter due to cutting resistance or vibration is applied during drilling, the deformation amount is at most a groove width dimension, and the fitting projection or fitting recess If the fitting protrusion has already been reduced in diameter due to dimensional tolerances, etc., the amount of deformation during drilling will be further reduced, and the elasticity (spring force) of the fitting protrusion due to slitting will be maintained well. Thus, a decrease in the coupling strength of the taper fitting is suppressed, and the body life is improved.

  The present invention is preferably applied to a twist drill in which the groove is twisted around the axis, but can also be applied to a straight blade drill in which the groove is parallel to the axis. An oil hole for supplying lubricating oil may be provided as necessary.

  As the body material, tool steel such as high-speed tool steel is preferably used, but other steel that can be elastically deformed by slitting can also be used. As the cemented carbide material for the tip, a cemented carbide is preferably used, but other cemented carbide material can also be adopted.

  The taper angle of the fitting protrusion and the fitting recess is suitably in the range of 5 ° to 15 °, for example, so that a predetermined coupling strength can be obtained by taper fitting. Further, when the fitting protrusion and the fitting recess are fitted to each other by rotating around the shaft center, the two are separated by a predetermined dimension in the axial direction with an inclined surface or the like protruding in the axial direction toward the circumferential direction. Further, both the tapered surfaces can be firmly taper-fitted.

  The direction of relative rotation when fitting the fitting protrusion and fitting recess is the same as the load acting between them during drilling, that is, the rotation of the fitting protrusion provided on the body during drilling It is desirable to fit them so that they can be rotated relative to each other in the same direction, and in the combined state where both phases match, if a stopper is provided to prevent further rotation, the body due to the load during drilling And the tip tip are prevented from shifting in phase (relative rotation), and rotational torque is transmitted from the body to the tip tip via the stopper.

  The groove width of the slot provided in the fitting protrusion is appropriately determined according to their dimensional tolerances so as to allow fitting of the fitting protrusion and the fitting recess, but depends on the load during drilling. In order to suppress the deformation, it is desirable that it is as narrow as possible, for example, about 0.5 mm or less. Further, it differs depending on the depth of the slot, and is preferably about 1/10 or less of the depth of the slot. For example, if the depth is 3 mm, the groove width is preferably 0.3 mm or less. The slot can be provided with high dimensional accuracy by, for example, wire cut electric discharge machining.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
FIG. 1 is a front view (a view seen from a direction perpendicular to the axis) of a tip portion of a throw-away drill according to an embodiment of the present invention, that is, a joint portion between a body 10 and a tip 12. FIGS. 2A and 2B are views showing the distal end portion of the body 10, wherein FIG. 2A is a perspective view, FIG. 2B is a plan view seen from the distal end side, and FIG. 2C is a side view seen from the right side of FIG. d) is a front view from the bottom of (b). 3 is a diagram showing the tip 12 alone, where (a) is a front view seen from a direction perpendicular to the axis, (b) is a side view seen from the right side of (a), and (c). (A) is a bottom view seen from below.

  This throw-away drill is a two-blade twist drill, and is provided with a pair of twist grooves 14 symmetrically with respect to the axial center so as to extend over the body 10 and the tip 12, The distal tip 12 is provided with cutting edges 16 at the distal opening portions of the pair of twisted grooves 14. The body 10 is made of high-speed tool steel, and an inverted taper-shaped fitting protrusion 18 having a larger diameter at the protruding end is provided concentrically and integrally at the tip, while the tip 12 Is made of cemented carbide, and a fitting recess 20 having a reverse taper shape is concentrically provided on the lower end surface so as to be fitted with the fitting protrusion 18. Both the fitting protrusion 18 and the fitting recess 20 are notched on the side surfaces by the twist groove 14, and the fitting protrusion 18 is moved in a state where the phase is shifted by about 90 ° around the axis as shown in FIG. 1 is inserted into the notch of the fitting recess 20, and the fitting protrusion 18 side is relatively rotated about 90 ° around the axis in the direction indicated by the arrow A, so that the fitting protrusion as shown in FIG. 18 and the fitting recess 20 can be fitted together and coupled together. The torsion groove 14 has a width dimension larger than that of the land, and both the fitting protrusion 18 and the fitting recess 20 are notched over an angular range of 90 ° or more around the axis. By shifting the phase around the shaft center by about 90 °, the fitting protrusion 18 can be inserted into the notch of the fitting recess 20 as shown in FIG.

  The drill diameter of the throw-away drill of this embodiment is 12 mm, and the taper angle of the reverse taper shape of the fitting protrusion 18 and the fitting recess 20 is about 10 °. Specifically, the diameter D1 of the distal end of the fitting protrusion 18 is 6.2 mm, the diameter D2 on the proximal end side is 5.5 mm, and the protruding dimension T is 4 mm. The diameter of the bottom of the fitting recess 20 is The dimension d1 is 6.2 mm, the diameter d2 of the opening is 5.5 mm, and the depth t is 4 mm. Further, the processing tolerance of the diameter D1 on the large diameter side is −0 to +0.1 mm, the processing tolerance of the diameter dimension d1 is −0.1 to +0 mm, and tightening fitting is basically performed on the large diameter side. The machining tolerance of the diameter D2 on the small diameter side is −0.1 to +0 mm, and the machining tolerance of the diameter d2 is −0 to +0.1 mm. The machining tolerance of the protruding dimension T is -0.1 to +0 mm, the machining tolerance of the depth t is -0 to +0.1 mm, the axial dimension is basically free, and can be fitted with a margin. it can.

  The fitting protrusion 18 is provided with a slit 22 penetrating in the radial direction at a predetermined depth from the tip surface, and can be elastically reduced in diameter. The protrusion 18 can be easily and reliably fitted into the fitting recess 20. The slot 22 is provided by wire-cut electric discharge machining, and has a depth dimension of about 3 mm and a groove width of about 0.2 mm.

  The rotation direction on the side of the fitting protrusion 18 indicated by the arrow A in FIG. 4 is the same clockwise rotation as the rotation direction of the body 10 at the time of drilling. , A pair of stoppers (engagement protrusions) 24 for preventing further rotation are integrally provided along the outer peripheral edge. The lower end surface of the tip 12 is provided with a notch 26 for receiving the stopper 24. When the stopper 24 is brought into contact with the circumferential end 26e of the notch 26, further relative rotation is prevented, A phase shift (relative rotation) between the body 10 and the tip 12 due to a load during drilling is prevented, and rotational torque is transmitted from the body 10 to the tip 12 via the stopper 24. Note that a chamfer 28 of about 0.3 mm is provided on the fitting side of the fitting protrusion 18, that is, the corner on the leading edge 30 side, so that it can be easily fitted into the fitting recess 20. ing.

  The upper surface of the stopper 24 is provided with an inclined surface that inclines so as to gradually protrude in the axial direction as it advances in the circumferential direction, and the bottom surface of the notch 26 is inclined corresponding to the stopper 24. When the fitting protrusion 18 is fitted into the fitting recess 20 by rotating the tip 12 and the tip 12 relative to each other around the axis, the two are separated in the axial direction by a predetermined dimension. As a result, the fitting protrusion 18 and the fitting recess 20 are taper-fitted more firmly, and the distal tip 12 is more strongly integrally coupled to the body 10. The stopper 24 and the notch 26 are respectively provided on the heel 32 side, and are engaged with each other in the latter half portion when the fitting protrusion 18 is fitted into the fitting recess 20 to separate them in the axial direction. Either one of the inclined surfaces of the stopper 24 and the notch 26 may be a flat surface perpendicular to the axis.

  According to such a throw-away drill of this embodiment, the fitting protrusion 18 is provided on the body 10, and the fitting protrusion 18 is provided with a slit 22 so that the diameter can be reduced elastically. Therefore, the fitting protrusion 18 can be easily and reliably fitted into the fitting recess 20. Further, even when a load in the direction of reducing the diameter of the fitting protrusion 18 is applied due to cutting resistance or vibration during drilling, the deformation amount is at most the groove width dimension of the slit 22 and the fitting protrusion 18 or When the fitting protrusion 18 has already been reduced in diameter due to dimensional tolerance of the fitting recess 20 or the like, the amount of deformation during drilling is further reduced, and the elasticity of the fitting protrusion 18 by the slot 22 is reduced. (Spring force) is maintained satisfactorily, a decrease in the coupling strength of the taper fitting is suppressed, and the life of the body 10 is improved.

  Incidentally, according to an experiment conducted by the present inventors using the throw-away drill of the above embodiment, the bonding strength is maintained well even after the tip 12 is replaced 10 times, and the body 10 is continuously used. The life of the body has more than doubled compared to the conventional product that can not be used 3 to 5 times.

  As mentioned above, although the Example of this invention was described in detail based on drawing, this is an embodiment to the last, and this invention implements in the aspect which added various change and improvement based on the knowledge of those skilled in the art. Can do.

It is a front view which shows the front-end | tip part of the throw away type drill which is one Example of this invention. It is a figure which shows the front-end | tip part of the body in the drill of FIG. It is a figure which shows the front-end | tip tip in the drill of FIG. It is a figure explaining the procedure at the time of carrying out fitting coupling | bonding of the front-end | tip tip of FIG. 3 to the body of FIG.

Explanation of symbols

  10: Body 12: Tip tip 14: Twist groove (groove) 16: Cutting edge 18: Fitting protrusion 20: Fitting recess 22: Slot

Claims (1)

A steel body with a wider width than the land and a pair of grooves in the axial direction;
A tip end made of a super hard material in which a pair of grooves are provided so as to be continuous with the groove, and a pair of cutting edges are formed in a tip opening portion of the groove;
A fitting protrusion having a reverse taper shape with a larger diameter on the tip side, provided concentrically on one of the body and the tip, and a side face notched by the groove;
A fitting recess having a reverse taper shape so as to be fitted with the fitting protrusion, being concentrically provided on the other of the body and the tip, and having a side face notched by the groove;
The fitting protrusion is inserted into the fitting recess in a state in which the phases of the body and the tip of the tip are shifted, and the fitting protrusion and the fitting protrusion are In the throw-away type drill that integrally couples the tip with the body so as not to be pulled out by the action of the reverse taper shape by fitting with the fitting recess,
A throw-away drill characterized in that the fitting protrusion is provided on the body, and a slit is provided in the fitting protrusion so that the diameter can be elastically reduced.

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