JP3657165B2 - Drilling machine tip structure - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a drilling machine that drills concrete, stone, building material, glass, and the like, and more particularly to a tip structure of a drilling machine that drills a small diameter.
[0002]
[Prior art]
For example, when a decorative plate is attached to a concrete wall of a building, it is necessary to drill many small-diameter holes for anchor bolts in the concrete wall. As such a small diameter drilling machine, a drilling machine in which a drill having a cutting part is attached to the tip of a rotating shaft is used.
[0003]
The basic configuration of this type of drilling machine is that a drill is attached to the tip of a hollow rotating shaft, and a drill such as air or water supplied through a flow path inside the rotating shaft is ejected from the tip of the rotating shaft. It is rotated and drilled while sucking cutting waste together with fluid, and is called a so-called non-core drill. As a dry drilling machine using compressed air as a fluid, there are drilling machines described in Japanese Patent Publication No. 3-4365 and No. 6-25307.
[0004]
As shown in the bottom view of FIG. 5 (a) and the longitudinal sectional view of FIG. 5 (b), the tip structure of the drilling machine described in Japanese Patent Publication No. 3-4365 is the cutting part 53 at the tip of the rotating shaft 51. In addition, a slit 55 is formed that opens across the concave tip surface 54 and the side surface, and a cutting edge 56 is formed at the intersection of the slit 55 and the tip surface 54. At the time of drilling, the compressed air that has passed through the flow path 52 of the rotating shaft 51 is ejected from the slit 55 to cool the cutting blade 56. According to this drilling machine, air can be supplied easily and smoothly under high-speed rotation, thermal degradation of the drill can be suppressed, cutting efficiency can be improved, and cooling and cutting of the drill can be achieved. Since the air circulation for discharging and collecting waste is maintained during drilling, it is said that good drilling can be performed throughout.
[0005]
As shown in the bottom view of FIG. 6 (a) and the longitudinal sectional view of FIG. 6 (b), the tip portion structure in the drilling machine described in Japanese Utility Model Publication No. 6-25307 is a rotation having a coolant flow path 62. An open space 65 that opens in a U-shape is formed in the cutting part 63 at the tip of the shaft 61, a cutting edge 66 is formed at the intersection of the open space 65 and the tip surface 64, and an open space 65 is further formed. A tapered surface 67 inclined toward the center of the base of the cutting part 63 is provided on the inner wall surface. By providing the tapered surface 67, the workpiece inside the cutting part is easily crushed by the tapered surface 67.
[0006]
Further, as a wet drilling machine using an aerosol coolant as a fluid, there is a drilling machine described in JP-A-11-10425. As shown in the bottom view of FIG. 7 (a) and the longitudinal sectional view of FIG. 7 (b), the drill structure in this drilling machine closes the tip of the hollow rotating shaft 71, leaving the coolant injection holes 77. In this drill structure, a flat surface 78 is provided, and a cutting portion 73 having a slit 75 formed in the flat surface 78 is provided. In this drill structure, the ejection hole 77 is prevented from being clogged by shifting the ejection hole 77 from the center of the rotation axis.
[0007]
Japanese Utility Model Laid-Open No. 5-39913 discloses a grinding drilling tool having a through hole at the center of a grinding member and a grinding fluid supply hole connected from the through hole to the outer peripheral portion of the grinding member. In this grinding and punching tool, it is said that a large amount of grinding fluid is supplied to the outer peripheral portion of the front end surface of the grinding member and can be efficiently ground.
[0008]
[Problems to be solved by the invention]
In the actual drilling operation, in the case of a dry drilling machine, the tip of the hollow part of the rotating shaft is not blocked, so the outlet of the compressed air will not be clogged. Since the tip of the part is blocked except for the coolant ejection hole, the coolant ejection hole is easily clogged. The perforating machine described in the above Japanese Patent Application Laid-Open No. 11-10425 prevents the clogging of the ejection holes by shifting the coolant ejection holes from the center of the rotation axis. In this perforation machine, the ejection holes are rotated. Even if it is deviated from the center of the shaft, the amount of eccentricity is small, and since the coolant is jetted near the center where the density of the chips is high, the chips hit the workpiece directly and the cooling effect is weakened. In addition, the coolant is not efficiently supplied to the outer peripheral portion of the drill, which is the portion with the highest peripheral speed during drill rotation and the highest grinding resistance, and sufficient grinding efficiency cannot be obtained. Moreover, since the open space is not formed in the grinding member, the grinding drilling tool described in Japanese Utility Model Laid-Open No. 5-39913 is in a state where the grinding member and the material to be ground are in close contact with each other, and cooling in the vicinity of the opening of the through hole is performed. Is effective, but the cooling effect of other parts is remarkably deteriorated, and chips are easily clogged.
[0009]
The problem to be solved by the present invention is to further improve the structure of the tip of the drilling machine used for drilling with a small diameter, to improve the efficiency of the supply of coolant, and to further improve the grinding efficiency.
[0010]
[Means for Solving the Problems]
The present invention relates to a drilling machine in which a drill is attached to a tip of a hollow rotating shaft, and a coolant supplied through a flow path inside the rotating shaft is ejected toward the tip of the drill, and the tip of the rotating shaft is cooled. A superabrasive grain segment having an internal space which is closed except for the agent ejection hole and has a part in the circumferential direction opened in a horizontal cross section is attached to the outer surface of the closed part to constitute a drill, and the hollow part of the rotating shaft A coolant ejection hole for ejecting coolant in an oblique direction from the position eccentric from the center of the tip toward the peripheral position of the outer surface of the closure portion is formed in the closure portion.
[0011]
In the drilling machine of the present invention, by forming an ejection hole in the obstruction portion for ejecting the coolant in an oblique direction from the position eccentric from the center of the distal end of the hollow portion of the rotating shaft toward the peripheral position of the outer surface of the obstruction portion, The coolant ejected from the ejection hole is ejected toward the outer peripheral portion of the drill, and the coolant is efficiently supplied to the outer peripheral portion having the highest grinding resistance, so that sufficient grinding efficiency can be obtained.
[0012]
The amount of eccentricity and the inclination angle from the rotation shaft center of the ejection hole is set so that the coolant is supplied to the outer peripheral portion of the drill according to the outer diameter of the drill and the height of the segment. In the case of a small-diameter drilling machine that is a subject of the present invention, it is desirable that the angle formed by the axis of the ejection hole and the axis of the rotating shaft be 5 to 45 degrees. When the inclination angle is less than 5 degrees, the coolant is not efficiently supplied to the outer periphery of the drill as in the case of the conventional drilling machine. On the other hand, when the inclination angle exceeds 45 degrees, the coolant sprayed toward the outer periphery of the drill is less likely to stay on the outer periphery. Further, since the rotating shaft has a small diameter and the thickness of the closed portion is thin, it is difficult to design a hole having a large inclination angle exceeding 45 degrees in an eccentric state in the closed portion.
[0013]
If the coolant ejection hole is inclined, the length of the ejection hole becomes longer, so that the resistance when the coolant passes through the ejection hole is increased, and the smooth supply of the coolant is hindered. . Therefore, it is desirable that the tip of the hollow portion is formed in a conical shape and the apex angle is 90 to 170 degrees. As described above, when the inclination angle of the ejection hole is 5 to 45 degrees, the vertex angle for making the axis of the ejection hole and the conical top surface become a right angle is 90 to 170 degrees.
[0014]
In addition, when the ejection hole is inclined, the front end surface of the closed portion of the rotating shaft and the axis of the ejection hole are not perpendicular to each other. It spreads and cannot be efficiently supplied to the outer periphery of the drill. Therefore, it is desirable to form the tip of the blocking portion in a conical shape and set the apex angle to 90 to 170 degrees. As described above, when the inclination angle of the ejection hole is 5 to 45 degrees, the vertex angle for making the axis of the ejection hole and the conical top surface become a right angle is 90 to 170 degrees.
[0015]
It is desirable to form an inclined surface in the direction in which the area on the tip side of the segment decreases on the inner wall surface forming the internal space of the segment. By forming the inclined surface on the inner wall surface, the area contributing to crushing of the cutting waste is increased, the crushing is promoted, and the dischargeability of the cutting waste is increased.
[0016]
As the superabrasive grains used for the segments, diamond abrasive grains and CBN abrasive grains used in conventional superabrasive drills can be used. These abrasive grains are bonded and held with a metal bond to form a segment having a predetermined shape, and this segment is joined to the end of the closed portion of the rotating shaft to form a drill. The coolant outlet is formed so as to open to a portion other than the segment attachment surface.
[0017]
DETAILED DESCRIPTION OF THE INVENTION
FIGS. 1A and 1B are views showing a tip portion structure of a drilling machine according to a first embodiment of the present invention, in which FIG. 1A is a bottom view and FIG. 1B is a sectional view taken along line AA in FIG.
[0018]
The structure of the tip portion 10 of the present embodiment is configured by joining a segment 4 having an inner space, which is partially open in the circumferential direction, to the tip of the closing portion 2 at the tip of the rotary shaft 1 by brazing. Is. The segment 4 is obtained by bonding and holding diamond abrasive grains with a metal bond.
[0019]
In this tip portion structure, a jet hole for jetting coolant in the oblique direction from the position eccentric from the center of the tip of the hollow portion 6 toward the peripheral position of the outer surface of the block portion 2 in the closed portion 2 at the tip of the rotating shaft 1. 3 is formed in the closed portion 2. An angle θ1 formed by the axis of the ejection hole 3 and the axis of the rotary shaft 1 is 15 degrees. By providing the ejection holes 3 at an inclination, the coolant ejected from the ejection holes 3 is ejected toward the outer periphery of the tip of the segment 4 constituting the drill, and the segment 4 having the highest grinding resistance. The coolant is efficiently supplied to the outer peripheral portion of the steel, and sufficient grinding efficiency can be obtained.
[0020]
FIGS. 2A and 2B are views showing the tip structure of the drilling machine according to the second embodiment of the present invention, in which FIG. 2A is a bottom view and FIG. 2B is a sectional view taken along line BB in FIG.
[0021]
The structure of the tip portion 20 of this embodiment is such that a segment 5 is attached instead of the segment 4 in the tip portion structure of the first embodiment. The segment 5 is formed by forming an inclined surface 5a on the inner wall surface forming the internal space in a direction in which the area on the segment tip side decreases. By forming this inclined surface 5a, the area which contributes to crushing of cutting waste becomes large, crushing is accelerated | stimulated, and the discharge property of crushing waste also improves.
[0022]
FIGS. 3A and 3B are diagrams showing a tip portion structure of a drilling machine according to a third embodiment of the present invention, in which FIG. 3A is a bottom view and FIG. 3B is a sectional view taken along the line CC of FIG.
[0023]
The structure of the distal end portion 30 of the present embodiment is obtained by changing the shape of the distal end of the hollow portion 6 in the distal end portion structure of the second embodiment. The tip of the hollow portion 6 is formed in a conical shape so that the tip end surface of the hollow portion 6 and the axis of the jet hole 3 are at right angles with the coolant injection hole 3 inclined, and the top surface 6a forms the tip. The apex angle θ2 is 150 degrees. Thus, by making the tip of the hollow portion 6 conical, the length of the ejection hole 3 becomes shorter than in the first and second embodiments, and the resistance when the coolant passes through the ejection hole 3 is reduced. Less.
[0024]
FIGS. 4A and 4B are views showing a tip portion structure of a drilling machine according to a fourth embodiment of the present invention. FIG. 4A is a bottom view, and FIG. 4B is a sectional view taken along line DD of FIG.
[0025]
The structure of the distal end portion 40 of the present embodiment is obtained by changing the shape of the distal end of the closing portion 2 in the distal end portion structure of the third embodiment. In a state where the coolant injection hole 3 is inclined, the tip of the blocking part 7 is formed in a conical shape so that the tip surface of the blocking part 7 and the axis of the injection hole 3 are perpendicular to each other. The formed apex angle θ3 is 150 degrees. Thus, by making the tip of the blocking part 7 conical and making the tip of the blocking part 7 and the axis of the ejection hole 3 perpendicular, the coolant does not spread at the opening of the ejection hole 3. Ejected toward the outer peripheral portion of the tip of the segment 8, efficient cooling can be performed. In the present embodiment, since the tip of the closing part 7 has a conical shape, the bottom surface of the segment 8 has a shape corresponding to the shape of the tip of the closing part 7.
[0026]
【The invention's effect】
The following effects can be achieved by the present invention.
[0027]
(1) By forming a blowout hole in the closed portion for injecting the coolant in an oblique direction from a position eccentric from the center of the tip of the hollow portion of the rotating shaft toward the peripheral position of the outer surface of the closed portion, the blowout is made from the blowout hole. Thus, the coolant is ejected toward the outer peripheral portion of the drill, and the coolant is efficiently supplied to the outer peripheral portion having the highest grinding resistance, so that a sufficient grinding efficiency can be obtained.
[0028]
(2) By forming the tip of the hollow part in a conical shape so that the tip of the hollow part and the axis of the jet hole are perpendicular to each other with the coolant injection hole inclined, Smooth inflow of coolant is maintained.
[0029]
(3) The tip of the closing part is formed in a conical shape so that the tip of the closing part and the axis of the injection hole are at right angles with the coolant injection hole inclined, and cooling is performed at the opening of the injection hole. The agent does not spread, and the coolant is ejected toward the outer peripheral portion of the drill tip, so that efficient cooling can be performed.
[0030]
(4) By forming an inclined surface in a direction in which the area on the tip side of the segment decreases on the inner wall surface forming the internal space of the superabrasive grain segment constituting the drill, the area contributing to crushing of the cutting waste increases. Crushing is promoted and cutting waste is improved.
[Brief description of the drawings]
FIG. 1 is a diagram showing a tip structure of a drilling machine according to a first embodiment.
FIG. 2 is a diagram showing a tip structure of a drilling machine in a second embodiment.
FIG. 3 is a diagram showing a tip structure of a drilling machine in a third embodiment.
FIG. 4 is a view showing a tip structure of a drilling machine in a fourth embodiment.
FIG. 5 is a diagram showing an example of a drill structure of a conventional drilling machine.
FIG. 6 is a view showing an example of a drill structure of a conventional drilling machine.
FIG. 7 is a view showing an example of a drill structure of a conventional drilling machine.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Rotating shaft 2, 7 Closure part 3 Coolant injection hole 4, 5, 8 Segment 5a, 8a Inclined surface 6 Hollow part 6a, 7a Top surface 10, 20, 30, 40 Tip part of punch

Claims (3)

In a drilling machine that drills while attaching a drill to the tip of a hollow rotating shaft and ejecting the fluid supplied through the flow path inside the rotating shaft toward the tip of the drill, the tip of the rotating shaft is blocked except for the fluid ejection hole And a superabrasive grain segment having an internal space that is partially open in the circumferential direction in a horizontal cross section is attached to the outer surface of the closed portion to constitute a drill, and is eccentric from the center of the tip of the hollow portion of the rotating shaft A fluid ejection hole for ejecting fluid in an oblique direction from the position toward the peripheral edge of the outer surface of the closed portion is formed in the closed portion, so that the distal end surface of the hollow portion and the axis of the fluid ejection hole are perpendicular to each other. The tip of the hollow portion is formed in a conical shape, and the tip of the closed portion is formed in a conical shape so that the tip surface of the closed portion and the axis of the fluid ejection hole are perpendicular to each other. Is 90-170 degrees Tip structure of the drilling machine, characterized in that.   The tip portion structure of a drilling machine according to claim 1, wherein an angle formed by the axis of the fluid ejection hole and the axis of the rotary shaft is 5 to 45 degrees.   The tip part structure of the drilling machine of Claim 1 or 2 which formed the inclined surface of the direction in which the area of the segment tip side reduces on the inner wall surface which forms the internal space of the said segment.

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