JP2007090565A - Core bit for drill - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To reduce the abrasion caused between concrete and a core and to easily discharge cut refuse produced at the time of drilling to the outside. <P>SOLUTION: This core bit for a drill is equipped with a shank 21 having a coolant flow channel 25 formed to its axial center and the grinding rubstone 6 fixed to the leading end of the shank 21 to internally communicate with the coolant flow channel 25. The grinding rubstone 6 has two almost semi-circular grinding blade parts 31a and 31b same in outer diameter but different in inner diameter. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a drill core bit that is used by being mounted on an electric drill when drilling concrete, tile, brick, stone, or the like.

A conventional drill core bit has a plurality of grinding tips whose inner and outer surfaces in the radial direction protrude from the inner and outer surfaces of the shank, and a radial direction at one end of the grinding tip by providing a notch on the radially inner surface at one end in the circumferential direction. And a grinding tip provided with a notch on the side adjacent to the grinding tip and adjacent to the grinding tip (see Patent Document 1).
JP 2000-127147 A

  In such a drill core bit, since the opposing grinding tip sandwiches the concrete core produced by drilling, a large frictional force is generated between the rotating grinding wheel and the core, and excessive frictional heat is generated. There was a problem that the drilling workability deteriorated. Moreover, since the core is pushed by the coolant flowing in from the shank side, it is easy to clog the grinding wheel part together with the drilled cutting waste, and the coolant flow path supplied from the shank is blocked, and the specific There was a problem that the tip could not be drilled due to rapid wear of the tip or galling.

  SUMMARY OF THE INVENTION An object of the present invention is to provide a drill core bit that can reduce friction generated with a concrete core and that does not cause clogging in a grinding wheel portion.

  The drill core bit of the present invention includes a shank having a coolant channel formed in an axis thereof, and a grinding wheel that is fixed to the tip of the shank and communicates with the coolant channel on the inside, and the grinding wheel has an outer diameter. Are substantially semicircular grinding blade portions having different inner diameters.

According to this configuration, since the inner diameters of the two grinding blade portions are different, the grinding blade portion does not sandwich the concrete core at any location in the circumferential direction. For this reason, the force toward the inner side in the radial direction with respect to the core of one grinding blade part escapes to the other grinding blade part side, and the frictional force due to rotation can be extremely reduced. Therefore, clogging of the grinding blade portion due to generation of frictional heat can be suppressed. In addition, since one grinding blade portion is formed thinner than the other grinding blade portion, a gap is generated between the core and the thin grinding blade portion. For this reason, the cutting waste generated at the time of drilling easily flows from the grinding blade portion to the outside through this gap, and at the same time, the gap does not hinder the flow of the coolant to the tip of the grinding blade portion. Clogging of the grinding wheel portion (inner side) and clogging of the grinding wheel itself can be prevented.
In addition, when the two grinding blade portions are continuous in the circumferential direction, the generation of noise and vibration is extremely suppressed as compared with the case where they are separated (there is a gap). In the separation type, each grinding blade portion may be composed of a single grinding tip or a plurality of grinding tips. The two grinding blade portions do not have to be strictly semicircular, and one of the grinding blade portions may have an arc shape exceeding the semicircle (approaching the circle).

  In this case, it is preferable that the two grinding blade portions are constituted by a single grinding tip continuous in the circumferential direction.

  According to this configuration, since the two grinding blade portions are continuous, noise and vibration can be extremely reduced, and at the same time, grinding performance can be improved.

  In this case, it is preferable that the two grinding blade portions are opposed to each other with an interval in the circumferential direction, and each is constituted by a single grinding tip.

  According to this configuration, each of the grinding blade portions can be produced relatively easily, and is particularly useful for a small-diameter grinding wheel.

  In these cases, the grinding wheel is preferably a diamond wheel.

  According to this configuration, even if the object to be drilled is a hard material such as stone or concrete, the opening edge of the insertion hole can be efficiently ground (punched).

  As described above, according to the drill core bit of the present invention, it is possible to reduce friction between the grinding wheel and the concrete core and to prevent clogging of this portion. In this way, the working efficiency of the grinding work can be improved.

  Hereinafter, an embodiment of a drill core bit (hereinafter referred to as “core bit”) and a drilling device to which the drill bit is attached will be described with reference to the accompanying drawings. This drilling device attaches a core bit to the tip of an electric drill via a coolant supply attachment, and drills a concrete (wall). The core bit is formed of a so-called diamond core bit.

  As shown in FIG. 1, the drilling device 1 includes a core bit 2 having a grinding wheel 6 for grinding concrete C at the tip, an electric drill 3 as a power source for rotating the core bit 2, a core bit 2, and an electric drill 3. A coolant supply unit 4 having a coolant supply attachment 7 interposed therebetween, and a coolant recovery unit (not shown: described later) for recovering coolant (coolant) supplied to the grinding wheel 6 together with cutting waste of the concrete C. And a guide unit 5 that holds the coolant supply attachment 7 and guides the drilling of the core bit 2.

  In the drilling operation, the coolant is supplied from the coolant supply unit 4 to the tip of the core bit 2, the core bit 2 is applied to a required drilling location via the guide unit 5, the core bit 2 is rotated by the electric drill 3, and the grinding wheel 6 drill the concrete C. In addition, the coolant supplied to the tip of the core bit 2 is recovered by the coolant recovery unit via the abutment block 15 described later in a state of being mixed with the cutting waste of the concrete C.

  The coolant supply unit 4 includes a pressurized coolant tank 11 for storing coolant, a coolant supply attachment 7 disposed coaxially between the core bit 2 and the electric drill 3, and a coolant tank 11. And a coolant tube 12 connecting the coolant supply attachment 7. The coolant is pressurized and supplied from the coolant tank 11 to the coolant supply attachment 7 via the coolant tube 12, and the coolant is supplied from the coolant supply attachment 7 to the core bit 2 in conjunction with the operation of abutting the core bit 2 against the concrete C. Supplied through its interior to its tip.

  The guide unit 5 has an attachment block 14 fixed to the outer peripheral surface of the coolant supply attachment 11, an abutment block 15 that abuts against the concrete C and has a connection port (not shown) to the coolant recovery unit, and an attachment. It is composed of two telescopic rods 16, 16 passed between the block 14 and the abutting block 15, and a coil spring 17 wound around one telescopic rod 16. When the core bit 2 cuts into the concrete C, the abutment block 15 is elastically pressed against the telescopic rod 16 and is abutted against the edge of the perforated hole A to guide the perforation of the core bit 2.

  As shown in FIGS. 2 to 4, the core bit 2 includes a grinding wheel 6 for drilling concrete C, and a shank 21 that holds the grinding wheel 6 at the distal end and is attached to the coolant supply attachment 7 at the proximal end. Consists of. The shank 21 includes a rod-shaped shank main body 22 having a grinding wheel 6 fixed to the tip, and a cylindrical joint recess 23 that is connected to the base end side of the shank main body 22 and is attached to the coolant supply attachment 7. Is formed. And the joint convex part 8 provided in the front-end | tip part of the coolant supply attachment 7 fits into this joint recessed part 23. FIG. That is, the core bit 2 is detachably attached to the distal end portion of the coolant supply attachment 7. The shank body 22 and the joint recess 23 may be separated and joined by screw joint or the like.

  Moreover, the core of the concrete C is called in to the axial center of the shank 21, and the coolant flow path 25 used as the flow path of a coolant is formed (refer FIG. 3). On the other hand, an attachment-side coolant channel 8 a that is continuous with the coolant channel 25 is also formed at the axis of the joint projection 8, and the coolant is supplied from the coolant supply attachment 7 to the coolant channel. 25 is supplied to the tip of the grinding wheel 6 (see FIG. 3). The core of the concrete C generated by grinding is relatively guided from the grinding wheel 6 to the coolant channel 25. The core guided to the coolant channel 25 is appropriately removed by removing the core bit 2 from the coolant supply attachment 7.

  The joint recess 23 is formed to have a diameter larger than that of the shank main body 22, and a pair of locking grooves 26 formed in an “L” shape are formed at 180 ° symmetrical positions on the peripheral surface thereof. On the other hand, a pair of locking pins 9 corresponding to the pair of locking grooves 26 are implanted in the above-mentioned bonding convex portion 8 that fits into the bonding recess 23, and an open portion of the pair of locking grooves 26 is formed. After aligning with the pair of locking pins 9, the joint recess 23 is pushed into the joint convex portion 8 and further rotated, whereby the joint concave portion 23 is attached to the joint convex portion 8 (see FIG. 2 for both). ). Further, a first O-ring 27 and a second O-ring 28 for sealing the coolant are interposed between the joint concave portion 23 and the joint convex portion 8, and on the tail end side. Positioned, a third O-ring 29 for absorbing vibration is interposed (see FIG. 3). Thereby, the leakage of the coolant from the joint portion between the core bit 2 and the coolant supply attachment 7 is prevented, and the vibration generated during the drilling operation is absorbed in this portion.

  As shown in FIGS. 3 and 4, the grinding wheel 6 is a so-called diamond wheel formed by sintering diamond abrasive grains and a binder, and has a substantially semicircular shape arranged oppositely at intervals. It is composed of two grinding tips 31a and 31b and a cylindrical tip base 32 having two grinding tips 31a and 31b fixed to the tips. A female screw 32 a is formed on the inner peripheral surface of the base end portion of the chip base 32, and a male screw 22 a is formed on the outer peripheral surface of the distal end portion of the shank body 22 correspondingly. Thus, when the grinding tips 31a and 31b are worn, the grinding wheel 6 can be removed and replaced at this portion. Note that the chip base 32 and the shank body 22 may be integrally formed.

  The two grinding chips 31a and 31b each have a substantially semicircular arc shape centered on the axis of the chip base 32, and are disposed to face each other with a gap in the circumferential direction. The two grinding tips 31a and 31b are formed in shapes having the same outer diameter and different inner diameters. That is, one grinding tip 31a is formed thick and the other grinding tip 31b is formed thin, and a coolant flow passage / core introduction passage is formed in the inner space of both grinding tips 31a, 31b. ing. As shown in FIG. 4, for example, when the diameter D of the grinding wheel 6 (outer diameters of both grinding tips 31a and 31b) 6 is 6 mm, the thickness T1 of one grinding tip 31a is 1.5 mm, The wall thickness T2 is 1.0 mm. Depending on the diameter of the grinding wheel 6 (relatively large diameter), each of the grinding chips 31a and 31b may be divided into two (4 chips in total).

  In the drilling of the concrete (wall body) C by the core bit 2, the concrete C is ground into a cross-sectional ring shape while leaving the center while supplying the coolant from the inside of the grinding wheel 6. Further, the core of the concrete C remaining in the center portion relatively enters the coolant channel 25 of the shank body 22 from the inside of the grinding wheel 6. Needless to say, the coolant channel 25 has a diameter larger than that of the core. Then, by drilling a hole A having a predetermined depth and pulling out the core bit 2, the core is also removed at the same time, and the hole A is completed.

  In such a configuration, when drilling, friction occurs between the inner sides of the rotating grinding chips 31a, 31b and the core of the concrete C (strictly speaking, circular motion). Since both the grinding tips 31a and 31b are not structured to sandwich the core of the concrete C, the force applied to the core escapes from the thick grinding tip 31a side to the thin grinding tip 31b side, and both grinding tips 31a. , 31b and the friction force between the core is reduced. Further, the coolant is smoothly supplied to the tip of the grinding wheel 6 from the gap between the core and the thin grinding tip 31b. Therefore, heat generation of both the grinding tips 31a and 31b is suppressed, and the clogging is suppressed, and the drilling ability of the core bit 2 is not lowered. That is, the working efficiency of drilling can be improved. Note that one of the grinding tips may have an arc shape exceeding a semicircle.

  Next, with reference to FIG. 5, a different part from the above is mainly demonstrated about 2nd Embodiment of the grinding stone 6 of this invention. In the grinding wheel 6 of this embodiment, two substantially semicircular grinding chips (31a, 31b) are continuous and formed as a single chip. That is, the grinding tip 41 is composed of a thick tip portion 41a and a thin tip portion 41b.

  Also in this case, the thick tip portion 41a and the thin tip portion 41b each have a substantially semicircular arc shape centered on the axis of the tip base 32, and are continuously opposed to each other in the circumferential direction. Further, the thick tip portion 41a and the thin tip portion 41b are formed in shapes having the same outer diameter and different inner diameters. That is, the thick tip portion 41a is formed to be thick and thin, and the thin tip portion 41b is thin. In the inner space of both the grinding tip portions 41a and 41b, a coolant flow passage / core introduction passage is formed. Yes. As shown in FIG. 5, for example, when the diameter D of the grinding wheel 6 is 6 mm, the thickness T1 of the thick tip portion 41a is 1.5 mm, and the thickness T2 of the thin tip portion 41b is 1.0 mm. . In addition, the continuous part of the thick tip part 41a and the thin tip part 41 may be a chamfered shape as well as a simple step as shown in FIG.

  With such a configuration, the same operation and effect as in the first embodiment described above can be obtained, and noise and vibration can be extremely reduced because there is no gap between the two grinding tip portions 41a and 41b. In this case as well, one of the grinding tip portions may have an arc shape exceeding a semicircle (the other is an arc shape less than a semicircle).

It is an external view of the perforation apparatus which concerns on one actual form of this invention. It is a perspective view around a core bit concerning an embodiment. It is a partial cutting side view of a core bit concerning an embodiment. It is a front view of the core bit which concerns on embodiment. It is a front view of the core bit which concerns on 2nd Embodiment.

Explanation of symbols

  2: Core bit 6: Grinding wheel 21: Shank 22: Shank body 25: Coolant flow path 31a, 31b: Grinding tip 41: Grinding tip 41a: Thick tip 41b: Thin tip

Claims (4)

A shank with a coolant channel formed in its axis;
A grinding wheel which is fixed to the tip of the shank and whose inner side communicates with the coolant channel,
The drill grinding bit according to claim 1, wherein the grinding wheel has two substantially semicircular grinding blade portions having the same outer diameter and different inner diameters.   2. The core bit for drill according to claim 1, wherein the two grinding blade portions are constituted by a single grinding tip continuous in a circumferential direction.   2. The drill core bit according to claim 1, wherein the two grinding blade portions are opposed to each other with an interval in the circumferential direction, and each is constituted by a single grinding tip.   4. The drill core bit according to claim 1, wherein the grinding wheel is a diamond wheel.

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