JP2008155310A - Non-core drill, and grinding method using the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a non-core drill for performing grinding work by giving an eccentric motion together with the rotational motion of a shank, which non-core drill can improve the grinding efficiency for hard and brittle materials. <P>SOLUTION: The non-core drill 1 comprises a diamond wheel portion 2 at the tip end of the shank 3 serving as a rotary shaft. The diamond wheel portion 2 is turned about the axis α of the shank 3. In addition, the eccentric motion is given to the diamond wheel portion 2 and the hard and brittle material 16 to be ground in order to carry out the grinding work. A recessed portion 14 is formed at least at the axis portion α of the shank in the tip end face 13 of the diamond wheel portion 2. The tip end face 13 of the diamond wheel portion 2 except the recessed portion 14 serves as a tip end abrasive surface for grinding the hard and brittle material 16. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a diamond drill for drilling a hard and brittle material such as glass.

  Conventionally, as a tool for making a hole in a hard and brittle material, there is a diamond drill that makes a hole by contacting a hard and brittle material while rotating a diamond grindstone attached to the tip of a steel shank. There are a core drill in which an axial through hole is formed and a non-core drill in which an axial through hole is not formed. In addition, when grinding with such a drill, the diamond wheel is brought into contact with the hard and brittle material while rotating the shaft about the shank axis, and between the diamond wheel and the hard and brittle material. Perforation is performed by giving an eccentric motion (for example, see Patent Document 1).

JP-A-2005-199619 (pages 5 and 7, FIGS. 1 and 18)

  However, in the non-core drill described in Patent Document 1, when the diamond grindstone is rotated about the shank axis, the outer peripheral portion of the front end surface of the diamond grindstone has a high peripheral speed. However, the axial speed at the tip surface of the diamond grindstone is almost free from peripheral speed due to shaft rotation. In this state, when grinding is performed by giving an eccentric motion between the diamond grinding wheel portion and the hard and brittle material to be ground, the outer peripheral portion of the front end surface of the diamond grinding wheel portion is added to the peripheral speed due to shaft rotation. Hard and brittle materials can be ground at a friction speed with the added speed due to the eccentric motion, but the shaft center of the tip of the diamond wheel is given an eccentric motion with almost no peripheral speed due to the shaft rotation. The hard and brittle material is ground only at the friction speed, and the portion of the hard and brittle material that is ground by the axial center portion of the tip surface of the diamond grindstone portion is likely to remain, and the remaining portion of the hard and brittle material is the diamond grindstone. By contacting the axial center of the tip surface of the part, the outer peripheral part of the tip surface of the diamond grindstone part becomes difficult to contact the hard and brittle material, and the grinding efficiency of the hard and brittle material by the non-core drill is reduced. There is a problem.

  The present invention has been made paying attention to such problems, and provides a non-core drill capable of improving the grinding efficiency of hard and brittle materials in a non-core drill that performs an eccentric motion along with shaft rotation to perform grinding work. The purpose is to do.

In order to solve the above problem, a non-core drill according to claim 1 of the present invention is provided.
A diamond grindstone portion is provided at the tip of the shank that acts as a rotating shaft, the diamond grindstone portion is rotated about the shank axis, and is eccentric between the diamond grindstone portion and the hard and brittle material to be ground. A non-core drill for imparting motion and grinding
A recess is formed at least in the axial center of the rotational axis of the tip surface of the diamond grinding wheel portion, and the tip surface of the diamond grinding wheel portion excluding the recess is a tip grinding surface for grinding the hard and brittle material. It is a feature.
According to this feature, when the diamond grindstone is rotated about the shank axis, the center of the diamond grindstone can be ground without contacting the hard and brittle material. Since the hard and brittle material can be ground only by the tip grinding surface which is the outer peripheral portion of the tip surface of the diamond grinding wheel portion having a high friction speed, the grinding efficiency of the non-core drill can be improved.

The non-core drill according to claim 2 of the present invention is the non-core drill according to claim 1,
The concave portion is configured to receive chips generated by grinding the hard and brittle material.
According to this feature, the chips generated by grinding the hard and brittle material are accommodated in the recess, and the chips are generated between the tip grinding surface of the diamond grindstone and the hard and brittle material. Reduces the grinding efficiency of non-core drills.

The non-core drill according to claim 3 of the present invention is the non-core drill according to claim 1 or 2,
The concave portion is characterized by at least one concave groove extending radially from the axial center portion of the tip surface of the diamond grindstone portion.
According to this feature, chips generated by grinding the hard and brittle material through the groove can be discharged to the side of the diamond grindstone.

The non-core drill according to claim 4 of the present invention is the non-core drill according to claim 1 or 2,
The diamond grindstone portion is formed with a through-hole penetrating from the inner space of the recess to the outside of the side periphery of the diamond grindstone portion.
According to this feature, the chips contained in the inner space of the recess can be discharged from the through hole to the outside of the side periphery of the diamond grindstone portion.

The grinding method using the non-core drill according to claim 5 of the present invention,
A grinding method for forming a substantially circular perforated portion in a hard and brittle material to be ground using a non-core drill provided with a diamond grindstone portion at the tip of a shank acting as a rotating shaft,
A recess is formed at least in the axial center portion of the rotation axis in the tip surface of the diamond grinding wheel portion, and the tip surface of the diamond grinding wheel portion excluding the recess is a tip grinding surface for grinding the hard and brittle material,
The diamond grindstone portion is rotated about the shank axis, and at least between the diamond grindstone portion and the hard and brittle material, provided that the tip grinding surface passes through the center point of the drilled portion. It is characterized in that the hard and brittle material is ground by giving an eccentric motion.
According to this feature, when the diamond grindstone is rotated about the shank axis, the center of the diamond grindstone can be ground without contacting the hard and brittle material. Since hard and brittle materials can be ground only with the tip grinding surface, which is the outer periphery of the tip of the diamond grinding wheel with high friction speed, the grinding efficiency of the non-core drill can be improved and the drilling part has a circular shape. By providing an eccentric motion between the diamond grinding wheel portion and the hard and brittle material on the condition that the tip grinding surface passes through the center point of the diamond, the diamond grinding wheel portion is positioned at a position corresponding to the recess when the shaft is rotated. The remaining portion of the resulting hard and brittle material can be eliminated by grinding with the tip grinding surface of the diamond grindstone portion that is eccentrically moved.

  The best mode for carrying out the non-core drill according to the present invention will be described below based on examples.

  An embodiment of the present invention will be described with reference to the drawings. First, FIG. 1 is a perspective view showing a non-core drill in Example 1, FIG. 2 is a front view showing the non-core drill, and FIG. 3 is a non-core drill. 4 is a longitudinal sectional side view showing a non-core drill, FIG. 5 is a cross-sectional view of a state in which the non-core drill is grinding a plate glass, and FIG. 6 is a non-core drill in FIG. FIG. 7 is a partial cross-sectional view of a state where the diamond grindstone portion chamfers the drilled portion. In the following description, the lower left side in FIG. 1 is the front side of the non-core drill, the left side in FIGS. 3 and 4 is the front side of the non-core drill, and the lower side in FIGS. 5 and 7 is the front side of the non-core drill. To do.

  1 is a non-core drill in Embodiment 1 to which the present invention is applied. The non-core drill 1 includes a diamond grindstone portion 2 on which diamond abrasive grains are mounted, and a steel shank 3 acting as a rotating shaft. It consists of and. The diamond grindstone portion 2 is manufactured as a metal bond grindstone or an electrodeposition grindstone using diamond abrasive grains.

  As shown in FIG. 3, the diamond grindstone portion 2 has a tip grindstone portion 4 having a small diameter formed on the tip side, an intermediate grindstone portion 5 formed in the intermediate portion and having a larger diameter than the tip grindstone portion 4, A proximal end grindstone portion 6 is formed on the proximal end side and has a larger diameter than the intermediate grindstone portion 5.

  Coarse diamond abrasive grains having a large particle diameter are attached to the tip grindstone part 4, and the grain diameter of the intermediate grindstone part 5 and the proximal grindstone part 6 is larger than that of the diamond abrasive grains attached to the tip grindstone part 4. Small fine diamond abrasive grains are attached.

  The proximal grindstone portion 6 has a substantially cylindrical shape, and a cylindrical surface 9 is formed on the side periphery of the proximal grindstone portion 6, and the distal end side of the proximal grindstone portion 6 faces the intermediate grindstone portion 5. A conical surface 12 formed so as to have a small diameter is formed.

  The intermediate grindstone 5 also has a substantially cylindrical shape, and a cylindrical surface 8 is formed on the side periphery of the intermediate grindstone 5, and the diameter of the intermediate grindstone 5 at the distal end side toward the distal grindstone 4. A conical surface 11 is formed so as to be small.

  Further, the tip grindstone 4 also has a substantially cylindrical shape, and a cylindrical surface 7 is formed on the side periphery of the tip grindstone 4, and the diameter decreases toward the tip on the tip side of the tip grindstone 4. A conical surface 10 formed as described above is formed. In the present embodiment, as shown in the partially enlarged perspective view of FIG. 1, the tip of the tip grindstone 4 is cut out at the tip of the cone formed by the conical surface 10 and formed into a flat surface. A tip surface 13 as a tip grinding surface is provided, and the shape of the tip portion of the tip grindstone portion 4 is a truncated cone shape.

  In the central portion (axial center portion) of the distal end surface 13 of the distal end grindstone portion 4, a minute concave portion 14 formed so as to penetrate through a substantially hemispherical shape is formed. As shown in FIG. 2, the tip surface 13 of the tip grindstone portion 4 has a substantially circular shape when viewed from the front of the non-core drill 1, and the recess 14 formed on the tip surface 13 is a concentric circle of the tip surface 13. Is formed. Further, as shown in the partially enlarged vertical side view of FIG. 4, the diameter i of the recess 14 is approximately one third or less of the diameter d of the tip surface 13.

  In addition, the recessed part 14 becomes a shape which becomes narrow as it goes to the back part, and the front end surface 13 and the inner surface of the recessed part 14 cross | intersect at the angle (theta) larger than a right angle in vertical side view. In the first embodiment, the angle θ at which the tip surface 13 and the inner surface of the recess 14 intersect is approximately 135 degrees. Furthermore, the back part of the recessed part 14 becomes the round surface 15 rounded by the predetermined curvature.

  The process of grinding the plate glass 16 as a hard and brittle material using the non-core drill 1 will be described in detail with reference to FIGS. As shown in FIG. 5, when the non-core drill 1 is used to grind the plate glass 16 that is a hard and brittle material, the tip grindstone portion 4 is first rotated while the non-core drill 1 is rotated about the axis α of the shank 3. Is brought into contact with the surface of the plate glass 16. At this time, since the tip of the tip grindstone 4 has a truncated cone shape, the pressing force is concentrated on the tip surface 13 and the glass sheet 16 is easily ground.

  Further, as shown in FIG. 6, the diamond wheel 2 of the non-core drill 1 rotates about the axis α of the shank 3, and a relative eccentric motion occurs between the diamond wheel 2 and the plate glass 16. It has come to be given.

  The eccentric motion of the non-core drill 1 will be described in detail. As shown in FIG. 6, the cylindrical surface 7 of the tip grindstone portion 4 of the non-core drill 1 is formed on the inner peripheral surface of a substantially circular perforated portion 17 formed on the plate glass 16. The non-core drill 1 is made so that the cylindrical surface 7 of the tip grindstone 4 abuts over the entire circumference of the inner peripheral surface of the drilling portion 17 while rotating the shaft in the direction a in FIG. It is sufficient to rotate the non-core drill 1 around the eccentric axis β as a planetary rotation by rotating it in the direction b in FIG. The eccentric shaft β is the center point of the perforated portion 17 having a circular shape.

  As a means for imparting a relative eccentric motion between the non-core drill 1 and the plate glass 16, a first motor (not shown) that rotates the non-core drill 1 about the axis α is set with the plate glass 16 stationary. And a second motor (not shown) for rotating the non-core drill 1 and the first motor (not shown) around the center (eccentric shaft β) of the drilling portion 17, and these first and second motors There is a method of giving a relative eccentric motion between the non-core drill 1 and the plate glass 16 by driving both (not shown).

  By grinding the non-core drill 1 while moving it eccentrically, a gap s with a predetermined interval is formed between the cylindrical surface 7 of the tip grindstone portion 4 and the inner surface of the drilled portion 17. By forming this gap s, it is possible to reduce the frictional resistance generated between the cylindrical surface 7 of the tip grindstone portion 4 and the inner peripheral surface of the drilled portion 17, so that the non-core drill 1 can be smoothly rotated. it can. In addition, by performing grinding while causing the non-core drill 1 to move in an eccentric manner in this manner, it is possible to perform drilling without causing cracks or the like on the inner peripheral surface of the drilled portion 17.

  Further, by giving an eccentric motion to the non-core drill 1, the diameter of the punched portion 17 formed in the plate glass 16 is formed to be slightly larger than the diameter of the tip grindstone portion 4. Note that the diameter of the drilled portion 17 changes depending on the separation distance e between the axis α of the rotation axis of the non-core drill 1 and the eccentric shaft β of the eccentric motion, and the distance between the axis α and the eccentric shaft β. If the distance e is large, the diameter of the perforated part 17 is formed large.

  Further, the non-core drill is such that the separation distance e between the axis α and the eccentric axis β is larger than the distance from the axis α to the inner edge of the nearest recess 14 (in this embodiment, the radius of the recess 14). 1 is given an eccentric motion. Therefore, when the diamond grindstone portion 2 is rotated, the remaining portion of the plate glass 16 generated at the bottom surface position of the perforated portion 17 corresponding to the concave portion 14 can be ground and eliminated by the front end surface 13 of the diamond grindstone portion 2.

  Further, the separation distance e between the axis α and the eccentric axis β is larger than the distance to the outer edge portion (the radius of the tip surface 13 in this embodiment) of the tip surface 13 of the diamond grindstone portion 2 farthest from the axis α. An eccentric motion is given to the non-core drill 1 so as to be small. Therefore, when the diamond grindstone portion 2 is eccentrically moved, the front end surface 13 of the diamond grindstone portion 2 grinds the plate glass 16 at a position corresponding to the eccentric axis β, and the plate glass 16 is located at a position corresponding to the eccentric shaft β. Thus, the remaining portion is not formed.

  That is, in the non-core drill 1 in the present embodiment, the diamond grindstone portion 2 is rotated about the axis α of the shank 3 and the tip surface 13 passes at least the center point (eccentric axis β) of the drilled portion 17. On the condition, the plate glass 16 is ground by giving an eccentric motion between the diamond grindstone portion 2 and the plate glass 16. Therefore, when the diamond grindstone 2 is rotated, the tip of the diamond grindstone 2 that is eccentrically moved at the position corresponding to the recess 14 or the remaining portion of the plate glass 16 generated at the center point (eccentric axis β) of the perforated portion 17. The surface 13 can be ground away.

  Moreover, since the recessed part 14 is formed in the position corresponding to the axial center (alpha) in the front end surface 13 of the front-end grindstone part 4, there is almost no peripheral speed when the non-core drill 1 is axially rotated centering on the axial center (alpha). Grinding can be performed without bringing the axial center portion (recessed portion 14) of the tip surface 13 of the tip grindstone portion 4 into contact with the plate glass 16. Therefore, it becomes possible to grind the plate glass 16 only by the outer peripheral portion of the tip surface 13 of the tip grindstone portion 4 having a high friction speed, that is, the tip grind portion 13, and the grinding efficiency of the non-core drill 1 can be improved.

  Moreover, the recessed part 14 can accommodate now the chip which generate | occur | produces when the plate glass 16 is ground. Therefore, it is possible to prevent a reduction in the grinding efficiency of the non-core drill 1 that occurs when the chips are interposed between the tip surface 13 of the diamond grindstone 2 and the plate glass 16. When grinding using the non-core drill 1, water can be poured into the gap s between the drilling portion 17 and the tip grindstone portion 4, and grinding can be performed while washing away chips and the like generated by grinding. ing.

  Further, as shown in the partially enlarged vertical side views of FIGS. 4 and 5, since rough diamond abrasive grains are attached to the tip grindstone portion 4, minute irregularities are formed on the surface of the perforated portion 17 formed by grinding. However, when the plate glass 16 is ground, the tip surface 13 and the inner surface of the recess 14 intersect with each other at an angle θ larger than a right angle. Even if there is some unevenness on the surface of the perforated part 17 located on the inner side, the surface of the perforated part 17 can be smoothly guided to the front end surface 13 of the front end grindstone part 4 by the inclination of the inner surface of the concave part 14. 14 It is possible to prevent chipping and wear at the periphery.

  Further, since the concave portion 14 has a shape that becomes narrower as it goes to the inner portion thereof, chips and the like generated during grinding of the glass sheet 16 are easily removed from the concave portion 14, and the chips and the like are easily removed from the concave portion 14. Since it becomes difficult to clog the inside, the non-core drill 1 after use can be easily maintained.

  Further, the contact area of the tip surface 13 of the tip grindstone portion 4 that grinds in contact with the plate glass 16 by the diameter i of the recess 14 being approximately one-third or less of the diameter d of the tip surface 13. It is possible to form the recesses 14 that do not contact the plate glass 16 while sufficiently securing the above and maintaining the grinding efficiency of the non-core drill 1.

  After the tip grindstone portion 4 penetrates the plate glass 16, the cylindrical surface 7 of the tip grindstone portion 4 is gradually increased by increasing the distance e between the axis α of the shaft rotation of the non-core drill 1 and the eccentric shaft β of the eccentric motion. Thus, the inner peripheral surface of the perforated part 17 is ground to enlarge the perforated part 17 so that the diameter of the perforated part 17 is increased.

  Then, after the diameter of the perforated part 17 is formed to a predetermined size, the diamond grindstone part 2 is further inserted into the perforated part 17, and the cylindrical surface 8 of the intermediate grindstone part 5 is brought into contact with the inner peripheral surface of the perforated part 17. Let Then, while rotating the non-core drill 1 about the axis α, the non-core drill 1 is centered on the eccentric axis β so that the cylindrical surface 8 of the intermediate grindstone 5 extends over the entire circumference of the inner peripheral surface of the drilled portion 17. As an eccentric exercise.

  Since the diamond abrasive grains finer than the diamond abrasive grains attached to the tip grindstone part 4 are adhered to the intermediate grindstone part 5, the intermediate grindstone part 5 can chamfer the inner peripheral surface of the perforated part 17. ing. The peripheral edge of the perforated part 17 can also be chamfered using the conical surface 11 of the intermediate grindstone 5 and the conical surface 12 of the proximal grindstone 6.

  Thus, after forming the perforated part 17 by penetrating the plate glass 16 using the tip grindstone part 4 to which coarse diamond abrasive grains are first attached, the perforated part is formed by the intermediate grindstone part 5 to which fine diamond abrasive grains are adhered. By chamfering 17, not only the grinding time for forming the perforated portion 17 in the plate glass 16 can be shortened, but also the exchanging drill 1 and other chamfering tools need not be replaced, and the perforated portion 17 is formed. The work time can be shortened.

  Next, the non-core drill 1a according to the second embodiment will be described with reference to FIG. Note that the same components as those shown in the first embodiment are denoted by the same reference numerals and redundant description is omitted. FIG. 8 is a vertical side view showing the non-core drill 1a in the second embodiment.

  As shown in FIG. 8, the concave portion 14 a formed in the non-core drill 1 a in Example 2 has a substantially conical shape at the center portion (axial center portion) of the tip surface 13 (tip tip grinding surface) of the tip grindstone portion 4. It is formed through. Similarly to the non-core drill 1a in the first embodiment described above, the tip surface 13 of the tip grindstone 4 has a substantially circular shape when viewed from the front of the non-core drill 1a, and the recess 14a formed on the tip surface 13 includes: The tip surface 13 is formed as a concentric circle.

  Further, similarly to the first embodiment, the diameter i of the concave portion 14a shown in the partially enlarged vertical side view of FIG. 8 is approximately one third or less of the diameter d of the distal end surface 13. The concave portion 14a has a shape that becomes narrower as it goes to the inner portion thereof, and the front end surface 13 and the inner surface of the concave portion 14a intersect at an angle θ larger than a right angle in a longitudinal side view. As in the first embodiment, the angle θ at which the tip surface 13 and the inner surface of the recess 14a intersect is approximately 135 degrees. Thus, even if the inner space of the recess 14a has a substantially conical shape, the grinding efficiency of the non-core drill 1a can be improved as in the first embodiment.

  Next, a non-core drill 1b according to Example 3 will be described with reference to FIGS. Note that the same components as those shown in the first embodiment are denoted by the same reference numerals and redundant description is omitted. FIG. 9 is a perspective view showing the non-core drill 1b in the third embodiment, and FIG. 10 is a conceptual plan view showing a grinding state of the non-core drill 1b in the third embodiment.

  As shown in the partial enlarged perspective view of FIG. 9, the tip of the cone formed by the conical surface 10 is cut out and formed into a flat surface at the tip of the tip grindstone 4 having a truncated cone shape. A tip surface 13 (tip grinding surface) is provided, and the tip surface 13 has a position corresponding to the axial center α (see FIG. 10) of the shaft rotation of the non-core drill 1b on the tip surface 13, that is, the central portion of the tip surface 13. A single groove groove 14b (concave portion) is formed so that the tip surface 13 extends radially from the central portion of the tip surface 13 and crosses the tip surface 13 through the (axial center).

  The concave groove 14b can temporarily accommodate chips generated by grinding the plate glass 16. Further, the chips accommodated in the groove 14b are rotated to the side of the diamond grindstone 2 while the non-core drill 1b is rotated, and the cylindrical surface 7 of the tip grindstone 4 and the drilled portion 17 It is discharged from the gap s (see FIG. 6) formed between the inner surface and the outside of the plate glass 16, and the non-cut generated when the chips are interposed between the tip surface 13 and the plate glass 16. A decrease in the grinding efficiency of the core drill 1b can be prevented.

  Also, as shown in FIG. 10, when the non-core drill 1b is rotated about the axis α, a circular portion r where the tip surface 13 does not come into contact due to the presence of the concave groove 14b is generated. A remaining portion r is generated in the plate glass 16 corresponding to the portion r. However, when the non-core drill 1b is eccentrically moved about the eccentric axis β, the tip surface 13 passes through the remaining portion r, and the remaining portion r is ground by the tip surface 13 and is eliminated. . Further, since the eccentric motion is given between the non-core drill 1b and the plate glass 16 on the condition that the tip surface 13 passes through the center point (eccentric axis β) of the drilling portion 17, the center point (eccentricity of the drilling portion 17 is eccentric. The remaining part of the plate glass 16 generated on the axis β) is also ground away.

  Next, a non-core drill 1c according to Example 4 will be described with reference to FIGS. Note that the same components as those shown in the first embodiment are denoted by the same reference numerals and redundant description is omitted. FIG. 11 is a perspective view showing the non-core drill 1c in the fourth embodiment, and FIG. 12 is a conceptual plan view showing a grinding state of the non-core drill 1c in the fourth embodiment.

  As shown in the partial enlarged perspective view of FIG. 11, the tip of the cone formed by the conical surface 10 is notched at the tip of the tip grindstone 4 having a truncated cone shape and is formed into a flat surface. A tip surface 13 (tip grinding surface) is provided, and the tip surface 13 has a position corresponding to the axial center α (see FIG. 12) of the shaft rotation of the non-core drill 1c on the tip surface 13, that is, the central portion of the tip surface 13. A concave groove 14c (concave portion) is formed so that the distal end surface 13 extends radially from the central portion of the distal end surface 13 through the (axial center portion) to form a substantially cross shape.

  The concave groove 14c can temporarily accommodate chips generated by grinding the plate glass 16. Moreover, the non-core drill 1c is axially rotated and the chips accommodated in the groove 14c are discharged to the side of the diamond grindstone portion 2 so that the cylindrical surface 7 of the tip grindstone portion 4 and the drilled portion 17 It is discharged from the gap s (see FIG. 6) formed between the inner surface and the outside of the plate glass 16, and the non-cut generated when the chips are interposed between the tip surface 13 and the plate glass 16. A decrease in the grinding efficiency of the core drill 1c can be prevented.

  As shown in FIG. 12, when the non-core drill 1c is rotated about the axis α, a circular portion r where the tip surface 13 does not come into contact due to the presence of the concave groove 14c is generated. A remaining portion r is generated in the plate glass 16 corresponding to the portion r. However, the non-core drill 1c is eccentrically moved about the eccentric axis β, so that the tip surface 13 passes through the remaining portion r, and the remaining portion r is ground and eliminated by the tip surface 13. . Further, since the eccentric motion is given between the non-core drill 1c and the plate glass 16 on the condition that the tip surface 13 passes through the center point (eccentric axis β) of the piercing portion 17, the center point (eccentricity of the piercing portion 17 is eccentric. The remaining part of the plate glass 16 generated on the axis β) is also ground away.

  Next, a non-core drill 1d according to Example 5 will be described with reference to FIG. Note that the same components as those shown in the first embodiment are denoted by the same reference numerals and redundant description is omitted. FIG. 13 is a cross-sectional view of a state in which the non-core drill 1d in Example 5 is grinding the plate glass 16.

  As shown in the partially enlarged longitudinal sectional side view of FIG. 13, the tip of the tip grindstone 4 having a truncated cone shape is cut out at the tip of the cone formed by the conical surface 10 to form a flat surface. A tip surface 13 (tip grinding surface) is provided, and a center portion (axial center portion) of the tip surface 13 is formed with a minute recess 14d formed so as to penetrate through a substantially hemispherical shape.

  Further, the tip grindstone 4 is formed with a through-hole 18 penetrating from the inner space of the recess 14 d to the conical surface 10 of the tip grindstone 4, that is, the outer side of the diamond grindstone 2. The recess 14d can temporarily store chips generated by grinding the plate glass 16.

  Moreover, the non-core drill 1 is axially rotated and the chips accommodated in the concave portion 14 pass through the through hole 18 and are discharged to the outside of the side periphery of the diamond grindstone portion 2. A gap s (see FIG. 6) formed between the surface 7 and the inner surface of the perforated portion 17 is discharged to the outside of the plate glass 16, and chips are disposed between the tip surface 13 and the plate glass 16. It is possible to prevent a decrease in the grinding efficiency of the non-core drill 1 caused by being interposed between the two.

  Although the embodiments of the present invention have been described with reference to the drawings, the specific configuration is not limited to these embodiments, and modifications and additions within the scope of the present invention are included in the present invention. It is.

  For example, in the said Example, although the front end surface 13 of the front-end grindstone part 4 is formed as a flat surface, the front-end | tip surface 13 does not necessarily need to be a flat surface, and in order to improve grinding efficiency, the front-end whetstone part 4 is. The front end surface 13 may have some irregularities, and if the convex portion protruding at least at a position (axial center portion) corresponding to the axial center α on the front end surface 13 is not formed, the concave portion 14 is formed. The same effect as that of the formed tip surface 13 can be obtained.

  Moreover, in the said Example, although the front-end | tip part of the front-end grindstone part 4 is formed in the truncated cone shape, the shape of the front-end | tip part of the front-end grindstone part 4 is not restricted to a truncated cone shape, It is cylindrical shape, Alternatively, it may be hemispherical, and if the minute concave portion 14 is formed at a position corresponding to the axial center α of the shaft rotation at the tip portion of the tip grindstone portion 4, the same as in the first embodiment. An effect can be obtained.

  Moreover, in the said Example 1, although the recessed part 14 was formed so that circular shape might be made in the front view of the non-core drill 1, the recessed part 14 does not need to be circular in front view, and is substantially triangular shape or substantially square shape. Or an elliptical shape. In the first embodiment, the non-core drill 1 is eccentrically moved so that the distance e between the axis α and the eccentric shaft β is larger than the radius of the recess 14. In the case of a quadrangular or elliptical shape, the distance e between the axis α and the eccentric axis β may be determined so as to be larger than the distance from the axis α to the inner edge of the nearest recess 14. .

1 is a perspective view showing a non-core drill in Example 1. FIG. It is a front view which shows a non-core drill. It is a side view which shows a non-core drill. It is a vertical side view which shows a non-core drill. It is sectional drawing in the state where the non-core drill is grinding plate glass. It is AA sectional drawing which shows the non-core drill in FIG. It is a partial cross section figure in the state where the diamond grindstone part chamfers the drilling part. It is a vertical side view which shows the non-core drill in Example 2. FIG. 10 is a perspective view showing a non-core drill in Example 3. FIG. 6 is a conceptual plan view showing a grinding state of a non-core drill in Example 3. FIG. It is a perspective view which shows the non-core drill in Example 4. It is a conceptual top view which shows the grinding state of the non-core drill in Example 4. It is sectional drawing of the state in which the non-core drill in Example 5 is grinding the plate glass.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1,1a Non-core drill 2 Diamond grindstone part 3 Shank 4 Tip grindstone part 5 Intermediate grindstone part 6 Base grindstone part 7, 8, 9 Cylindrical surface 10, 11, 12 Conical surface 13 Tip surface (tip grind surface)
14, 14a Concave part 14b, 14c Concave groove (concave part)
14d Recess 15 Round surface 16 Flat glass (hard and brittle material)
17 Perforated part 18 Through hole

Claims (5)

A diamond grindstone portion is provided at the tip of the shank that acts as a rotating shaft, the diamond grindstone portion is rotated about the shank axis, and is eccentric between the diamond grindstone portion and the hard and brittle material to be ground. A non-core drill for imparting motion and grinding
A recess is formed at least in the axial center of the rotational axis of the tip surface of the diamond grinding wheel portion, and the tip surface of the diamond grinding wheel portion excluding the recess is a tip grinding surface for grinding the hard and brittle material. Features a non-core drill.   2. The non-core drill according to claim 1, wherein the concave portion is configured to accommodate chips generated by grinding the hard and brittle material.   The non-core drill according to claim 1 or 2, wherein the concave portion is at least one concave groove extending radially from an axial center portion of a tip surface of the diamond grindstone portion.   The non-core drill according to claim 1 or 2, wherein a through-hole penetrating from the inner space of the concave portion to the outside of the side periphery of the diamond grindstone portion is formed in the diamond grindstone portion. A grinding method for forming a substantially circular perforated portion in a hard and brittle material to be ground using a non-core drill provided with a diamond grindstone portion at the tip of a shank acting as a rotating shaft,
A recess is formed at least in the axial center portion of the rotation axis in the tip surface of the diamond grinding wheel portion, and the tip surface of the diamond grinding wheel portion excluding the recess is a tip grinding surface for grinding the hard and brittle material,
The diamond grindstone portion is rotated about the shank axis, and at least between the diamond grindstone portion and the hard and brittle material, provided that the tip grinding surface passes through the center point of the drilled portion. A grinding method using a non-core drill, characterized in that the hard and brittle material is ground by giving an eccentric motion to the surface.

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