JP5400559B2 - Drilling with non-core bits - Google Patents

Description

  The present invention relates to a method for drilling a concrete structure using a non-core bit.

  There are a method of drilling a concrete structure using a hammer drill and a method of using a core drill. Of these methods, the former method using a hammer drill generates a lot of vibration and noise in order to hit a hole and perform drilling, whereas the latter method using a core drill has the advantage that the drilling operation can be performed quietly. is there.

  Non-core bits are often used in methods for drilling relatively small diameters in concrete structures. FIG. 1 shows an example in which this type of non-core bit 1 is attached to a hand-held type drill 2. The non-core bit 1 has a tip 3 formed of a diamond tip, and is generated when the tip 3 is cooled and drilled. In order to discharge chips, cooling water or air is passed through a through-hole formed along the axial center and is ejected from the slit 4 of the blade edge 3 or air is discharged from the slit 4 of the blade edge 3. Is sucked together with the chips and discharged, and an example thereof is disclosed in Patent Document 1 below.

JP-A-11-10425

  The cutter generally has a cutting speed at which the sharpness can be best exhibited. Similarly, for non-core bits, there is an appropriate rotation speed, and if the rotation speed is too slow, the cutting time will be longer or abnormal wear will occur. On the other hand, if the rotation speed is too fast, the cutting edge will be clogged. Or seizure, resulting in inability to cut.

  In the non-core bit, cutting is performed at all parts from the center part to the outer periphery of the blade edge, but the problem is that the peripheral speed is different between the center part and the outer periphery of the blade edge. In other words, the peripheral speed, which is 0 at the center, increases as it goes toward the outer periphery, and the larger the diameter, the greater the difference in peripheral speed between the center and the outer periphery. However, if the peripheral speed at the center portion is set appropriately, the peripheral speed at the outer periphery becomes too high and the above-described trouble occurs. It is impossible to set the peripheral speed to an appropriate range over the entire range from the center to the outer periphery as the diameter increases.

According to the experiments by the present inventors, it has been found as a result of the experiments that the above-described trouble occurs remarkably in a non-core bit of 15 mmΦ or more.
An object of the present invention is to provide a drilling method using a non-core bit that can solve the above-described problems.

The invention according to claim 1 is a method of drilling a concrete structure using a non-core bit. First, a small-diameter leading hole is formed in the concrete structure using a small-diameter non-core bit, and then a diameter larger than the preceding hole. The non-core bit is used, and the outside of the preceding hole is cut to form an enlarged hole concentric with the preceding hole,
The invention according to claim 2 is the invention according to claim 1, wherein the large-diameter non-core bit has a cone shape at least at the tip end of the blade tip, and is positioned by fitting the tip end portion of the blade tip into the leading hole. Cutting is performed using the preceding hole as a guide.

  The invention according to claim 3 is the invention according to claim 1, wherein the large-diameter non-core bit has a projecting portion having a circular cross section that fits into the leading hole at the tip of the blade tip, and the projecting portion is fitted into the leading hole. After positioning together, cutting is performed using the preceding hole as a guide.

  According to the invention relating to claim 1, in drilling a concrete structure, first, a leading hole is formed using a small-diameter non-core bit, but the small-diameter non-core bit has a peripheral speed from the center of the blade edge to the outer periphery. Because the difference is small, drilling with the drill speed set appropriately does not deviate significantly from the proper peripheral speed at any part of the cutting edge. Therefore, the cutting edge is clogged, baked or drilled for a long time. Drilling can be performed normally and efficiently without causing problems such as work and abnormal wear. After forming the leading hole, an enlarged hole is formed using a large-diameter non-core bit. However, the large-diameter non-core bit is not in contact with the concrete structure because the center of the blade edge corresponds to the leading hole. No drilling is performed. Drilling is performed at the peripheral edge of the cutting edge where it hits the concrete structure, and since the difference in peripheral speed between the inside and outside of the periphery is small, even if the drill is set to an appropriate rotational speed, Formation can be performed normally and efficiently.

  After forming the diameter-expanded hole, the diameter of the hole can be expanded using a larger non-core bit. Therefore, by using a plurality of non-core bits having different diameters in order from the smallest diameter and repeating the drilling operation, it is possible to perform drilling with a larger diameter normally and efficiently.

  The non-core bit of the present invention is attached to a drill when drilling, but the drill may be a fixed type or a hand-held type as shown in FIG. If the drill is a fixed type, drilling can be done without shifting the center of the bit even if drilling in multiple times, but if it is a hand-held type, the drill you have is easy to move, so the diameter of the preceding hole is increased. The center of the hole is easily displaced. In this regard, as in the invention according to claim 2, positioning is performed by fitting the tip of the blade edge to the preceding hole, and when the hole is drilled, the leading hole becomes a guide and the non-core bit is pushed forward. It becomes possible to reliably form an enlarged hole concentric with the hole.

  Further, as in the invention according to claim 3, after positioning by fitting the protrusion into the preceding hole, the leading hole is also used as a guide, and the non-core bit is pushed forward to expand the diameter concentric with the preceding hole. A hole is surely formed.

Side view of a hand-held drill with a non-core bit attached. The figure which shows the state immediately before making a preceding hole in a concrete structure. Sectional drawing which made the preceding hole in the concrete structure. The front view of the principal part of a large diameter non-core bit. The same side view. The figure which shows the state just before forming an enlarged diameter hole using the non-core bit shown in FIG. Sectional drawing which opened the diameter expansion hole in the concrete structure. The front view of the principal part of another example of a large diameter non-core bit. The same side view.

  Hereinafter, as an embodiment of the present invention, a method of attaching a non-core bit to the hand-held drill 2 shown in FIG.

  First, as shown in FIG. 1, a relatively small non-core bit 1 having an outer diameter of about 10 mmΦ is attached to a hand-held drill 2, and a drilling operation is performed on the concrete structure 5 shown in FIG. Form (FIG. 3). This leading hole 6 is a blind hole in the illustrated one, but may be a through hole penetrating the concrete structure 5.

  After forming the preceding hole, the non-core bit 1 is then removed from the drill 2 and the non-core bit 7 shown in FIGS. 4 and 5 is attached. This non-core bit 7 has an outer diameter of about 20 mmΦ, and a projection 9 having a diameter of 10 mmΦ, which is the same diameter as the non-core bit 1, is provided at the tip of the cutting edge 8. It is sucked together with the powder and can be discharged through an axial through hole (not shown).

  The diameter of the leading hole 6 is increased by fitting the protrusion 9 of the non-core bit 7 attached to the drill 2 into the leading hole 6 (FIG. 6). Thereby, positioning of the non-core bit 7 is performed, and after the positioning, a drilling operation is performed. In the drilling, the leading hole 6 serves as a guide for the protrusion 9 during drilling, and can be drilled concentrically with the leading hole 6. FIG. 7 shows the formed enlarged diameter hole 12. When the preceding hole 6 is a through hole, the enlarged diameter hole 12 is also formed as a through hole.

  According to the present embodiment, the perforated hole 6 is first formed using the non-core bit 1 having an outer diameter of about 10 mmΦ, but the bit 1 having a diameter of about 10 mmΦ has a small difference in peripheral speed between the center portion and the outer periphery of the blade edge. Normal drilling can be performed efficiently without greatly deviating from the appropriate peripheral speed in any part of the hole. After the perforated hole 6 is formed, the diameter-expanded hole 12 is formed using the non-core bit 7 having an outer diameter of about 20 mmΦ. The center portion of the cutting edge of the non-core bit 7 corresponds to the preceding hole 6 and the concrete structure 5 Not done to drilling into. Drilling in the concrete structure 5 is performed between 10 mmΦ to 20 mmΦ at the peripheral edge of the cutting edge, and the difference in the peripheral speed between the inside and outside is small. Therefore, even if the drill 2 is set to high speed rotation, concentric expansion with the preceding hole 6 is performed. The formation of the diameter hole 12 can be performed normally and efficiently.

When forming an enlarged hole larger than the enlarged hole 12 shown in FIG. 7, a non-core bit having a larger outer diameter is used.
8 and 9 show another example of a non-core bit having an outer diameter of about 20 mmΦ. In the non-core bit 15 shown in the figure, the tip of the blade edge 16 has a cone shape, and the cone-shaped tip portion 16a has a leading edge. It is smaller than the diameter of the hole 6 and is positioned by being fitted into the preceding hole 6.

Even when the non-core bit 15 of the present embodiment is used, the leading hole 6 serves as a guide during drilling and can be drilled concentrically with the leading hole 6 so that the enlarged diameter hole can be formed normally and efficiently.
The non-core bits 1, 7, 15 of the above embodiment are adapted to be attached to a hand-held type drill, but can be attached to a fixed type in which the drill is fixed to the concrete structure 5. Drilling with a relatively large diameter can be performed normally and efficiently.

1, 7, 15 ..Non-core bit 2 ..Drill 3, 8, 16 ..Cutting edge 4, 11 ..Slit 5 ..Concrete structure 6 ..Previous hole 9 .. Projection 12.

Claims (3)

  In a method of drilling a concrete structure using a non-core bit, first, a small diameter non-core bit is used to form a small diameter leading hole, and then a non-core bit having a diameter larger than the preceding hole is used. A non-core bit drilling method characterized in that the outside of the hole is cut to form an enlarged hole concentric with the preceding hole.   The large-diameter non-core bit is characterized in that at least the tip of the cutting edge is formed in a cone shape, and the cutting is performed using the leading hole as a guide after the tip of the cutting edge is fitted and positioned in the leading hole. A drilling method using the non-core bit according to 1.   A large-diameter non-core bit is provided with a circular cross-sectional protrusion that fits into the leading hole at the tip of the blade, and after positioning the protruding part into the leading hole, cutting is performed using the leading hole as a guide. The method for drilling with a non-core bit according to claim 1, wherein: