JP2011194868A - Abrasive core drill - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an abrasive core drill to be mounted on an electric tool for boring a concrete, ceramics, etc., which extends lifetime of the core drill 10 times or more as compared with conventional core drills.SOLUTION: In the present abrasive core drill, a slit is formed in a cylindrical boring part upon fixing abrasive grain formed by diamond, a cubic crystal of boron nitride, etc. to the boring part of the core drill with the use of a binding agent, etc. and the abrasive grain is fixed also to the inside of the slit. The boring can be continued by the abrasive grain in the slit even when the top end of the core drill is worn by boring, thereby remarkably extending the lifetime of the core drill as compared with a conventional abrasive core drill that cannot bore when an abrasive grain at the cylindrical top end of the core drill is worn.

Description

  The present invention relates to an abrasive core drill used for drilling in floors, walls, plates made of concrete, ceramics, and the like.

  When it is necessary to pass water pipes or electrical wiring through concrete floors, ceramic walls, etc. of buildings, abrasive core drills that can be drilled by attaching to electric or air tools are widely used. ing.

  An example of the abrasive grain type core drill 1 is shown in FIG. The metal body 3 is provided with a shank part 2 on one side and a perforated part 4 having an abrasive grain fixing part 9 on the other side.

FIG. 11 shows an enlarged cross-sectional view of the abrasive individual piece 9. As the abrasive grains 10 that contribute to cutting, particles made of a hard substance such as industrial diamond and cubic boron nitride are used, and are fixed to the perforated portion 4 of the body 3 by a method such as electrodeposition or welding.
In the drawing, the abrasive grains 10 are shown in a circular shape for the sake of convenience, but in actuality, they are polyhedrons such as cubes and rectangular parallelepipeds, and the corners and the angular portions of the polyhedron function as cutting blades for drilling. Although the actual dimensions of the abrasive grains vary, the average value is the abrasive grain dimension d, and all are shown as abrasive grains having the same dimensions.

  7 and 8 are a front sectional view and a left side view of a general abrasive grain core drill. Abrasive grains are fixed to the perforated portion 4, but are omitted from the drawing for easy understanding. At the center of the body 3, there is provided an extraction waste discharge hole 5 for discharging extraction residue generated by perforation, and is connected to the extraction waste discharge port 7 around the center of the body 3.

  When this abrasive core drill 1 is brought into contact with an object to be drilled made of concrete or the like and rotated at a high speed by an electric tool or air tool, the abrasive core 10 is fixed to the tip 3 of the body 3 to form a cylinder. When the tip-shaped portion 13 penetrates the drilled object, a hole substantially equal to the outer shape of the core drill is opened in the drilled object.

  During drilling, in the drilling unit 4, the drilled object cut with the abrasive grains 10 becomes fine particles. Since these particles destroy the abrasive grains 10, wear out, or cause the abrasive grains 10 to deviate from the body 3, the drilling performance deteriorates as the drilling is repeated.

  When the abrasive core drill 1 passes through the drilled object, a punched residue 12 is generated. For example, when a hole is drilled three times in the object to be drilled, as shown in FIG. The diameter of the punched residue 12 is smaller than the inner diameter of the punched residue discharge hole 5, and the length is equal to the thickness of the drilled object.

  As shown in the front cross-sectional view of FIG. 9 and the left side view of FIG. 10, when the punched residue 12 occupies most of the punched residue discharge hole 5, the drilled object is removed from the punched residue discharge hole 5 during the next drilling. The perforation does not proceed when hitting the punched residue 12. In order to avoid this, if the extracted residue 12 accumulates in the extracted residue discharge hole 5, it is necessary to remove the extracted residue 12 from the extracted residue discharge port 7 side or the perforated portion 4 side.

  However, in many cases, the fine particles of the drilled object generated at the time of drilling fill the gap between the punched residue discharge hole 5 and the punched residue 12 and the removal of the punched residue 12 is not easy.

  Further, as shown in the enlarged view of FIG. 11, the conventional abrasive core drill 1 has an abrasive 10 fixed to an abrasive fixing portion 9 of a cylindrical perforated portion 4 by a method such as electrodeposition or welding. However, normally, only one layer of the abrasive grains 10 is fixed to the abrasive grain fixing portion 9 of the body 3 as a base material for fixing. The reason is that even if the abrasive grains 10 are fixed to the base material in multiple layers, the bonding force between the abrasive grains is extremely weaker than the binding force between the base material and the abrasive grains, so that the upper layer abrasive grains can be easily cut by impact during cutting. It is only the first layer of abrasive grains fixed to the surface of the base material that deviates from the hole saw and ultimately contributes to cutting.

  Therefore, if the angular portion of the abrasive grains of the first layer is worn away or the abrasive grains deviate from the base material due to impact during cutting, etc., the cutting becomes impossible at that time.

  To extend the life of the abrasive core drill, that is, the period until the cutting function is stopped, select abrasive grains that do not chip off the angular portions of the abrasive grains for a long time, and generate heat and vibration generated during cutting. However, it is important to firmly fix the abrasive grains so that they do not easily deviate from the base material. Even if it is used, if the abrasive grains of the first layer diamond fixed to the surface of the base material are chipped due to cutting impact or peeled off from the base material, the life as a core drill will be exhausted.

  As described above, in the abrasive grain type core drill, generally, only the first layer of abrasive grains fixed to the surface of the base material is perforated, so that the angular shape of the abrasive grains becomes spherical, If it deviates from the base material, the life as a drilling tool is reached, so when performing many drilling, the core drill has to be frequently replaced, which causes problems in terms of workability and cost.

Also, if drilling is performed several times, the scraps will be accumulated in the punching waste discharge hole, making it impossible to drill. Therefore, it is sometimes necessary to remove the punching scraps from the punching waste discharge hole. Due to the fine particles of the object, the waste was clogged in the discharge hole, and the removal work was not easy.
The object of the present invention is to provide an abrasive core drill that solves these drawbacks.

  An abrasive core drill according to the present invention for solving the above-mentioned problems is characterized in that a plurality of slits are provided in a perforated portion, and the abrasive grains are fixed therein.

  In addition, a discharge inclined surface is provided on the side of the extraction waste outlet of the extraction waste discharge hole so that the removal of the extraction waste can be easily performed.

  For drilling, as with conventional abrasive core drills, the abrasive core drill according to the present invention is attached to the tool gripping part of an electric tool or air tool, and this is rotated at approximately the same number of revolutions as before. What is necessary is just to press against non-perforated objects such as walls, floors, and plates made of ceramics.

  As the drilling progresses and the abrasive grains fixed to the tip of the core drill wear out and deviate from the base material of the core drill, the underlying abrasive grains that did not contribute to drilling contact with the drilled object. And drilling continues. Next, when the abrasive grains deviate, the lower-layer abrasive grains continue to perforate. In this way, the next new abrasive grain continues to drill, and after all the abrasive grains in the slit have contributed to the drilling, the life as a core drill is reached. Compared to conventional abrasive core drills that only contribute to drilling, it is possible to achieve a lifetime of more than 100 times if the slit depth and width are selected appropriately.

  According to the abrasive core drill according to the present invention, since all the abrasive grains fixed in the slits provided in the perforated part contribute to the drilling, the conventional abrasive core drill in which only one layer of the abrasive grains is fixed Compared to tens of times, in some cases, a long life can be realized, and in some cases, it is easy to discharge the scraps that occur every time drilling is performed. The cost of purchasing can also be greatly reduced.

Front sectional view of an abrasive core drill in one embodiment of the present invention Left side view of an abrasive grain core drill in one embodiment of the present invention The figure which shows the whole abrasive grain type core drill The expanded sectional view of the drilling part of an abrasive grain type core drill in one example of the invention of this application FIG. 4 is a diagram for explaining the slit of the perforated part before the abrasive grains are fixed. Front sectional drawing for demonstrating discharge | emission of punching waste put on the abrasive grain type core drill in one Example of this invention. Front sectional view in one embodiment of a conventional abrasive core drill Left side view of an embodiment of a conventional abrasive core drill Front sectional drawing for demonstrating discharge | emission of punching waste in one Example of the conventional abrasive grain type core drill Left side view for explaining discharge of punching residue in an embodiment of a conventional abrasive core drill Expanded cross-sectional view of the drilled part of a conventional abrasive core drill

    In the abrasive grain type core drill according to the present invention, a slit is provided in the perforated portion, and the abrasive grains are also fixed therein. The abrasive is a so-called angular polyhedron such as a cube or a rectangular parallelepiped. The material may be hard particles such as industrial diamond and cubic boron nitride, which are generally used for grinding, and it is not necessary to use particles unique to the present invention.

  The slit provided in the perforated part to which these particles are fixed is formed with a width that allows one or more abrasive grains to fit. In general, since there are variations in the size of the abrasive grains, one or more abrasive grains is a value counted on the basis of abrasive grains having an average size.

The width of the base material portion remaining between the slits, that is, the portion called a tooth, is suitably about 1.2 to 10 times the size of the abrasive grains. If the strength of the base material to which the abrasive grains are fixed is strong, the width of the teeth may be narrow, but as described later, if it is too narrow, the drilling performance and life may be deteriorated. It is necessary to select the tooth width together.
Although the depth of the slit depends on the strength of the base material, it is easy to produce about 10 to 30 times the outer diameter of the abrasive grains and is suitable in terms of strength.

  When the abrasive core drill made in this way is mounted on a power tool or pneumatic tool, rotated, and abutted against a drilled object such as concrete, ceramics, etc., the abrasive grains fixed to the tip of the core drill remove the drilled object. When cutting is started and drilling is completed, the scraps of the workpiece remain in the slipping hole discharge holes in the core drill.

  When the drilling is repeated several times, the upper layer abrasive grains directly in contact with the drilled object are chipped or deviated from the core drill. Then, the abrasive grains fixed to the lower layer of the abrasive grains and closer to the bottom of the slit start to abut on the drilled object and continue drilling. When the abrasive grains deviate from the core drill, further lower abrasive grains continue cutting. In this way, when the abrasive grains fixed in the slit continue to perforate and all the abrasive grains have finished contributing to cutting, the service life is reached.

  The teeth of the base metal are metal and do not have a drilling function, but since the diameter of the abrasive grains is relatively large compared to the width of the teeth, most of the abrasive grains are not affected by the teeth and are not affected by the teeth. The drilling can be performed in contact with each other, and the drilling speed is not significantly reduced even if the abrasive grains are not fixed to the tip of the tooth. In addition, the tip of the tooth is scraped by particles scraped from the drilled object during drilling or abrasive grains that deviate from the base material, so that the abrasive grains fixed in the slit are maintained in a direction in which they easily come into contact with the drilled object. A substantially constant drilling speed is maintained until all the abrasive grains in the slit are exhausted by the drilling.

  In addition, when drilling is repeated, the scraps accumulate in the slipping hole discharge hole of the abrasive core drill, but when there is a certain amount of slipping, it is discharged so that it is pushed out from the slipping outlet along the discharge inclined surface. Therefore, the next drilling can be performed continuously without the need to interrupt the operation for removing the waste.

  As described above, according to the abrasive grain type core drill of the present invention, by fixing the abrasive grains in the slit, compared to the conventional abrasive grain type core drill in which only one layer of the abrasive grains is fixed, from several tens of times Tool life can be reduced by hundreds of times, resulting in significantly reduced tooling and efficient drilling, as well as significant savings in tool purchase costs, especially when a large number of holes need to be drilled. .

The abrasive core drill according to the present invention will be described with reference to FIGS. 1, 2, 3, 4, 5, and 6.
In addition, since the dimension of the abrasive grain 10 generally varies, the average value thereof is referred to as the abrasive grain dimension d in the description.

  FIG. 3 shows the whole of an abrasive grain type core drill 1 according to the present invention. The external appearance is the same as that of a conventional abrasive grain type core drill, and is composed of a shank portion 2, a body 3, and a perforated portion 4. The material used to manufacture the abrasive grain type core drill 1 according to the present invention may be the same iron-based material as the material used in a general abrasive grain type core drill. In the perforated portion 4 of the body 3, abrasive grains 10 made of a hard material suitable for cutting a material to be perforated such as industrial diamond or cubic boron nitride are formed by a method such as electrodeposition or welding. Adhering to the perforated part 4 to form an abrasive fixed part 9.

FIG. 4 shows an enlarged cross section of the perforated part 4 to which the abrasive grains 10 are fixed, and FIG. 5 shows an enlarged cross section of the perforated part 4 before the abrasive grains 10 are fixed.
As shown in FIG. 5, a plurality of slits 8 are formed in the perforated portion 4. The slit is formed by a disc cutter or the like attached to a machining center or the like in the perforated portion 4 of the body 3 made of a metal material. The dimensions after processing are defined as slit width A, tooth width B, and slit depth C, respectively. The outer diameter of the body 3 is D, and the thickness of the body is E.
In FIG. 5, the tooth thickness is illustrated as being the same as the body thickness E, but depending on the application, the tooth thickness may be reduced toward the tip of the tooth.

  The slit 8 is formed so that the slit width A is a width necessary to securely fix the abrasive grains 10, specifically, about 1.2 to 3 times the abrasive grain size d. In particular, when the abrasive grain size variation is large, that is, when abrasive grains in which a small grain size and a large grain size are mixed at a high ratio are used, the slit width A is 1 of the average grain size d. The smaller one such as 2 times is preferable because the strength when the abrasive grains 10 are fixed to the slits 8 later is strong and stable. The slit depth C may be large as long as the strength of the perforated portion 4 can be maintained, but 5 to 10 times the abrasive grain size d is empirically appropriate.

  In principle, the abrasive grain size d can be 5 mm, but such a large abrasive grain, for example, an industrial diamond grain having a dimension of 5 mm, is not only very expensive, but also a base material such as steel. It is difficult to secure the adhesion strength that can withstand the impact during cutting, and easily deviates from the base material. For example, it is practical to use abrasive grains having a size of about 0.3 mm or 0.5 mm.

  The tooth width B of the teeth 11 is preferably about 1 to 3 mm when the body outer diameter D is about 10 mm. If the tooth width B is too narrow, the teeth may be deformed or damaged by impact or vibration during drilling. Although the teeth 11 themselves do not directly contribute to drilling, when the body outer diameter D, the abrasive grain size d, and the slit width A are the same, if the tooth width B is reduced, the number of slits 8 processed in the drilled portion increases. . If the number of slits in the perforated part is too large, conversely, it is empirically known that if there are too many abrasive grains to contribute to perforation in the perforated part, the perforation speed may decrease, It is important that the tooth width B is not too small.

  After processing the slit 8, as shown in FIG. 4, the abrasive grains 10 are fixed to the perforated portion 4 by electrodeposition, welding, or the like while the abrasive grains 10 are fixed inside the slit 8. The fixing portion 9 is formed.

  Next, with reference to FIGS. 1 and 2, the discharge of the punched residue 12 in the abrasive grain core drill 1 according to the present invention will be described. The cylindrical body 3 of the abrasive grain type core drill 1 is provided with a punching waste discharge hole 5. The punched portion discharge hole 5 passes through the side of the perforated portion 4, and the side of the shank portion 2 is connected to the punched residue discharge port 7 via the discharge inclined surface 6.

  When drilling in an object to be drilled such as a concrete floor or a ceramic wall, the shank portion 2 is mounted on a tool gripping portion of an electric tool or air tool (not shown), and the entire abrasive core drill 1 is rotated at a predetermined rotational speed. Is rotated so that it comes into contact with the object to be drilled. Then, drilling of the drilled object is started by the abrasive grains 10 fixed to the drilling portion 4 of the abrasive grain type core drill 1, and when the abrasive grain core drill 1 penetrates the drilled object, the punching residue 12 is punched and the scrap discharging hole is formed. Remain at 5.

  In FIG. 6, front sectional drawing of the abrasive grain type core drill 1 which concerns on this invention after drilling is repeated 3 times is shown. The three punched residues 12 accumulated in the punched waste discharge hole 5 by the drilling are guided in the direction of the punched waste discharge port 7 by the discharge inclined surface 6 and discharged from the abrasive core drill 1 by the next fourth drilling. go. Thereafter, each time the perforation is repeated, the punched residue 12 is continuously discharged from the punched residue discharge port by the action of the discharge inclined surface 6.

  When the drilling is repeated, the abrasive grains 10 fixed to the tip portion 13 of the abrasive core drill 1 deteriorate and finally deviate from the tip portion 13 due to an impact during drilling. Then, the abrasive grains fixed in the lower layer of the deviated abrasive grains in the slit 8 start to drill. At this time, since the teeth 8 made of metal are worn at the tip portion 13 by the particles of the drilled object to be drilled or the abrasive grains that have deviated, the abrasive grains in the slit 8 always come into contact with the object to be drilled. It is possible to maintain a stable perforated state.

  As described above, according to the abrasive grain type core drill of the present invention, it is possible to perform the drilling until all the abrasive grains fixed in the slit are consumed, and it is possible to very easily discharge the waste by punching. Drilling workability and service life are dramatically improved.

DESCRIPTION OF SYMBOLS 1 Abrasive grain type core drill 2 Shank part 3 Body 4 Perforated part 5 Drainage discharge hole 6 Discharge inclined surface 7 Drainage discharge port 8 Slit 9 Abrasive fixed part 10 Abrasive grain 11 Teeth 12 Extraction dregs 13 Tip A A Slit width B Teeth Width C Slit depth D Body outer diameter d Abrasive grain size E Body thickness

Claims (1)

    An abrasive core drill connected to a power tool and used for drilling in concrete, ceramics, etc., wherein a slit having a width larger than the diameter of the abrasive is provided in the drilling portion of the core drill, and the inside of the slit Abrasive-type core drill characterized in that abrasive grains are also fixed on

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