JP3382748B2 - Diamond drill bit for dry drilling - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The present invention does not use cooling water or other working liquids when drilling a relatively small diameter with a maximum diameter of 20 mm or less for hard and brittle materials such as stone and concrete. In addition, the present invention relates to a diamond drill bit for dry drilling, which can be easily operated simply by mounting it on a normal drill and enables high-speed drilling.

[0002]

2. Description of the Related Art Diamond core bits have been widely used as a drilling tool used for drilling holes in hard and brittle materials such as stone materials and concrete structures. These diamond core bits are perforated by a mechanism in which a diamond grindstone formed of diamond abrasive grains and a bond is attached to the tip of a hollow cylindrical body, and a hard and brittle material is cut through the rotary motion of the bit.

However, since the tip of the diamond grindstone of these conventional diamond core bits is formed on a flat end face cut perpendicularly to the rotation axis of the body, when it is rotated to make a hole in concrete, for example, The cutting surface is also a plane perpendicular to the axis of rotation of the body. For this reason, the centrifugal force in the outer peripheral direction generated by the rotational motion acts on the cutting chips generated by cutting, but the direct driving force to be discharged toward the opening is expected because the cutting surface is flat. In addition, since the angle between the cutting surface and the boring wall is a right angle, retention of cutting debris occurs in the horizontal operation to prevent the diamond grindstone from biting into the cutting surface, and the boring speed is significantly reduced.

When the drilling speed decreases, the sliding friction phenomenon between the tip of the rotating grindstone and the accumulated cutting debris and the cutting surface of the work material becomes dominant rather than the cutting phenomenon, and the frictional heat associated therewith occurs remarkably. In addition, the heat radiation effect to the work material due to cutting and drilling is also reduced. Therefore, the heat accumulation of the grindstone is increased and seizure occurs, and the deterioration and deterioration of the cutting edge diamond occur, causing a vicious cycle in which the drilling speed further decreases.

Such a phenomenon is that the smaller the diameter of the diamond core bit, the smaller the heat capacity and the heat radiation area of the bit itself, and the more the heat of the cutting edge is accumulated. Has hardly been put to practical use. Further, since the conventional diamond core bit has a flat cutting edge,
When a load is applied in the drilling direction, no centripetal force is generated at the cutting edge, and especially in the drilling work with a hand-held rotary tool, whirling of the tool occurs and the hole diameter increases, which remains a problem.

[0006]

In order to solve the above problems, wet drilling forcing cooling of the cutting edge and discharge of cutting chips by supplying water or an appropriate working liquid to the cutting edge from the hollow hole of the body. Diamond core bits for use have also been proposed, but this method requires equipment for supplying water or processing liquid and a dedicated rotating tool, as well as measures for pollution of the work environment due to drainage or drainage, electric shock accident countermeasures, etc. However, it takes a lot of trouble to set up before work and clean up after work, and since the core of the work material and cutting chips accumulate in the inner hole of the body, it is also necessary to interrupt the work and discharge them. However, it was not suitable for a small-diameter drilling work that requires a high speed work.

On the other hand, a dry drilling method has also been attempted in which a carbide drill bit is attached to a vibrating drill, and drilling is performed while simultaneously imparting vibration and rotary motion, but in this case, noise pollution due to violent vibration noise is a problem. In addition, there is a drawback that the life of the cutting edge is remarkably shortened and the burden on the operator is increased in the drilling work of a concrete structure having high hardness due to severe wear of the cutting edge.

In order to make up for such a drawback, in Japanese Patent Laid-Open No. 1-206004, a diamond grindstone is used in place of the cemented carbide tip instead of the tip cutting edge of the cemented carbide drill bit, and the width of the tip cutting edge of the diamond grinding stone is changed. An example of a drill for hard and brittle materials in which a recessed groove of 0.5 to 2 mm is provided to form a non-cutting zone is shown. However, if the cemented carbide tip is simply replaced with a diamond grindstone, the center portion of the tip of the cutting edge becomes a dead point at a peripheral speed of zero, the cutting resistance becomes large, and it becomes impossible to perforate only the rotary motion. In addition, the phenomenon of deterioration of the cutting edge due to the progress of heating of the chip is likely to occur. Further, even if the above-mentioned recessed groove is provided on the tip edge of the diamond grindstone, in a bottomed section where the recessed groove is shallow, the core is immediately clogged immediately after starting the drilling work, and the drilling is continued for a long time. It becomes difficult to do the work.

The object of the present invention is to solve various problems which have been problematic in the prior art, and to form small holes having a hole diameter of 20 mm or less in hard and brittle materials such as concrete and stone materials, by using water or processing. It is an object of the present invention to provide a diamond drill bit for dry drilling, which can be mounted on a simple general-purpose tool without using a liquid or the like to perform drilling work at high speed and continuously.

[0010]

In order to achieve the above object, a diamond drill bit for dry drilling according to the present invention has a diamond grindstone integrated with a tip portion of a body provided with a spiral groove along an outer circumference in the axial direction. A diamond drill bit for dry drilling with a combined structure, wherein the cutting edge shape of the diamond grindstone is formed into a truncated cone shape with a diameter reduced from the joint surface with the body toward the tip, and the rotation axis of the diamond grindstone is The main structural feature is that at least one vertical groove that extends from the tip end surface including the blade to the body rotation axis and communicates with the spiral groove is formed.

In the present invention, a more preferable constitution is that the width of the vertical groove extending from the frustoconical cutting edge surface of the diamond grindstone to the body rotation axis is not less than 1 mm and not exceeding 5 mm, and the maximum outer diameter of the diamond grindstone is set. The diameter is 20 mm, the outer diameter of the body is 98% or less, and the angle of inclination of the truncated cone forming the cutting edge of the diamond grindstone is 70 to 30 ° with respect to the rotation axis.

[0012]

In the diamond drill bit for dry drilling according to the present invention, the diamond grindstone is integrally bonded to the tip of the body provided with the spiral groove along the outer circumference in the axial direction, and the shape of the diamond grindstone is bonded to the body. Characterized by a structure that has a frustoconical cutting edge shape whose diameter decreases from the surface to the tip, reaches the body rotation axis from the cutting edge tip surface including the rotation axis of the diamond grindstone, and communicates with the spiral groove Be attached. According to this structure, cutting debris generated during drilling is smoothly discharged from the spiral groove of the body to the outside of the rear system via the centrifugal force due to the rotational movement and the driving force generated by the inclination angle, and the phenomenon of staying on the cutting edge surface is effective. Be blocked. At the same time, the core that grows at the center of the cutting edge is constantly discharged from the rear opening from the spiral groove of the body through the slit-shaped vertical groove that is formed in communication with the body from the diamond grindstone.

In these operations, since the vertical groove is formed in a shape including the rotational axis of the tip surface of the body, the dead point at the tip of the diamond wheel tip at zero peripheral speed can be eliminated to the wear limit of the diamond wheel. Since the vertical groove reaches the body rotation axis and communicates with the spiral groove, both functions of the vertical groove and the spiral groove for guiding the cutting waste are combined, and the work material core is effectively removed from the system. It is brought about by discharging. Therefore, in the structure in which the vertical groove does not reach the rotation axis of the body and does not communicate with the spiral groove, the above-mentioned smooth exclusion function cannot be exhibited.

As a more specific constitution, the maximum outer diameter of the diamond grindstone is 20 mm, and the outer diameter of the body is 98% thereof.
By setting the inclination angle of the truncated cone of the cutting edge of the diamond grindstone to 70 to 30 ° with respect to the rotation axis, it is possible to sufficiently enhance the cutting effect, cutting waste discharging effect and heat dissipation effect. .

The above-mentioned respective actions are synergistically performed, and hard and brittle materials such as stones and concrete are drilled at an excellent drilling speed within a short time.
Drilling work of less than mm can be performed. On the other hand, by having a frustoconical cutting edge shape, centripetal force is generated at the cutting edge during drilling, so even when drilling work with a hand-held rotary tool, whirling motion of the tool is suppressed, and machining accuracy is high,
It is possible to perform hole processing that is close to a perfect circle.

[0016]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described in detail below with reference to the drawings. FIG. 1 is a partially cutaway vertical sectional view illustrating a diamond drill bit for dry drilling according to the present invention, FIG. 2 is a plan view of a tip portion of FIG. 1, and FIG. 3 is a sectional view taken along line AA of FIG. is there. In these figures, 1 is a body that constitutes a rotation base shaft part, 2 is a spiral groove provided along the outer circumference of the body 1 in the axial direction, 3 is a diamond grindstone integrally bonded to the tip of the body, and 4 is It is a vertical groove provided in a slit shape. The body 1 provided with the spiral groove 2 is mounted on a rotary tool (not shown) such as an electric drill and operates as a rotary member, and is usually replaced by a shank of a commercially available twist drill.

The shape of the diamond grindstone 3 is designed to be a truncated cone shape whose diameter is reduced from the connecting surface with the body 1 toward the tip portion, and this shape allows the tip inclined surface 5 of the grindstone to be formed.
A centrifugal force is generated due to the rotational movement, and a driving force that smoothly moves and discharges the cutting scraps rearward through the spiral groove 2 is generated. The vertical groove 4 provided in the diamond grindstone 3 is formed so as to reach the tip end surface including the rotary shaft of the diamond grindstone to the rotary shaft of the body and communicate with the spiral groove 2. The vertical groove 4 is cut into one or a plurality of lines so as to completely cover the rotation axis 6 of the body front end surface (see FIG. 3), and the passage shape is such that the tip communicates with the spiral groove 2 of the body 1. If it is, it may be inclined from the tip to the rear (groove bottom) or may be linear. The width (d) of the vertical groove 4 is 1
The diameter is designed to be wider in accordance with the outer circumference (D) of the diamond grindstone 3 in the range of mm or more, but it is preferable that the range is not more than 5 mm when the maximum perforation diameter is 20 mm or less. If the width of the vertical groove 4 is less than 1 mm, the peripheral speed of the central portion of the diamond grindstone becomes slow and the drilling ability is extremely lowered.
If it exceeds 5 mm, the bonding area between the grindstone and the body will be reduced and it will not be possible to maintain a sufficient bonding force. Moreover, the core strength of the work material generated at the center of the cutting edge will increase and gradually grow, resulting in vertical grooves 4 and spiral grooves. Crushing at 2 becomes difficult. For this reason, smooth discharge becomes impossible, and there is a possibility that perforation may be impossible due to clogging.

On the other hand, the most preferable dimensional design in the present invention is that the maximum outer diameter (D) of the diamond grindstone 3 is 20 mm,
The outer diameter (D ') of the body 1 is 98% or less, preferably 90% or less. The outer diameter (D ') of the body 1 is set to 98% or less of the outer diameter of the diamond grindstone 3 because a proper gap is formed between the body 1 and the perforated wall, and the tip inclined surface 5 of the grindstone is used for cutting. This is to reduce the frictional resistance when the cutting waste of the cut work material is discharged backward by the rotational driving force, and at the same time, effectively radiate the frictional heat generated at the cutting edge. The spiral groove 2 of the body 1 develops on the tip end surface of the diamond grindstone 3,
It plays an effective role as a passage for transferring the cutting waste sent to the rear through the outer periphery of the diamond grindstone 3 and the core of the work material generated at the central portion of the diamond grindstone 3 toward the rear opening, and further, the cutting edge. It effectively functions as a heat radiation path that releases frictional heat.

The inclination angle (θ) of the truncated cone which constitutes the cutting edge of the diamond grindstone 3 is preferably set in the range of 70 to 30 ° with respect to the rotation axis. This tilt angle (θ) is 7
If the angle exceeds 0 °, the cutting edge of the diamond grindstone 3 becomes dull, and the driving force for transferring and discharging the cutting chips to the rear decreases,
At an acute angle of less than 30 °, the tip strength of the diamond grindstone 3 decreases, the cutting edge area increases, cutting resistance increases, and the load applied to the cutting edge increases, which adversely affects the life of the diamond grinding wheel.

The vertical groove 4 extending from the tip end surface including the rotation axis of the diamond grindstone 3 to the rotation axis of the body makes the bite of the cutting edge good and prevents the accumulation of frictional heat generated at the cutting edge.
At the same time, it functions to increase the driving force that transfers the cutting debris backward with the rotation of the inclined surface of the grindstone, and at the same time crushes the core of the work material generated at the center of the cutting edge of the diamond grindstone 3 into the spiral groove 2. Transfers and plays a role in promoting discharge to the rear opening.

When the diamond drill bit for dry drilling according to the present invention is used, the chips of the work material generated on the inclined surface of the tip of the diamond grindstone 3 are transferred to the body 1 via the centrifugal force and the driving force generated by the inclination angle. It is smoothly discharged rearward from the gap between the perforated wall and the spiral groove 2. At the same time, the core of the work material generated at the center of the cutting edge is transferred from the diamond grindstone 3 to the spiral groove 2 through the vertical groove 4 provided in communication with the spiral groove 2 as the boring work progresses, and is smoothly removed from the system along with the cutting waste. Is discharged to. At this time, the core of the work material is finely crushed in the process of passing through the vertical groove 4 and the spiral groove 2, and is easily discharged in the state of cutting waste that does not retain the shape of the core.

Specific examples of the present invention will be given below for comparison with comparative examples. However, the present invention is not limited to these examples.

Example 1 A diamond grindstone having a truncated cone shape having an outer diameter (D) of 10.5 mm, a height of 6.0 mm, and an inclination angle (θ) of 60 °, which was formed of a cobalt bronze-based bond and diamond abrasive grains, was prepared.
Soldered to the tip of a twist drill type steel body with an outer diameter of 9.5 mm and a total length of 140 mm, this diamond grindstone has a slit-shaped vertical groove with a width of 3.0 mm centered on the rotation axis and communicates with it. As described above, a slit-shaped vertical groove having a depth of 6.5 mm and a width of 3.0 mm that passes through the rotation axis is provided in the steel body, and the tip end portion of the vertical groove is inclined so that the slit-shaped vertical groove is formed. The end portion was communicated with the spiral groove to form a cutting debris guiding path. Thus, as shown in FIGS. 1 to 3, the vertical groove 4 reaches the body rotation axis from the tip end surface including the rotation axis of the diamond grindstone 3 and communicates with the spiral groove 2 for dry drilling diamond drill. I made a bit.

The diamond drill bit for dry drilling described above was mounted on an electric rotary drill, and the rotation speed was 1600 rpm.
When pressed against a concrete plate (material age: 3 months, aggregate grain size: 15 mm, plate thickness: 60 mm) with a load of 20 kg and drilling work was performed, the core of the work material was formed from a diamond grindstone into a steel body. In the process of passing through the slit-shaped vertical groove, it was crushed and passed smoothly through the spiral groove in communication and was discharged smoothly to the outside of the system. In addition, the cutting dust generated on the tip surface of the grindstone is also efficiently discharged through the spiral groove of the body and can be continuously drilled dry without using cutting water or cooling water. The average drilling speed is 80 mm.
It was / min.

Example 2 An outer diameter (D) of 6.5 mm, a height of 5.0 mm and an inclination angle (θ) formed by a cobalt bronze-based bond and diamond abrasive grains.
A diamond grindstone having a 60 ° truncated cone shape is brazed to the tip of a twist drill type steel body having an outer diameter of 5.5 mm and a total length of 140 mm, and the diamond grindstone has a width of 1.0 mm centered on the rotation axis. A slit-shaped vertical groove is formed on the steel body so as to communicate with the slit-shaped vertical groove having a depth of 3.5 mm and a width of 1.0 mm, and the tip portion of the vertical groove. An end portion of the slit-shaped vertical groove was made to communicate with the spiral groove by forming an inclination to form a cutting waste guide path. In this way, as shown in FIGS.
, A diamond drill bit for dry drilling having a structure that reaches from the tip end surface including the rotation axis of the diamond grindstone 3 to the body rotation axis and communicates with the spiral groove 2.

The above diamond drill bit was fitted into an electric rotary drill, and at a rotation speed of 1600 rpm, a concrete plate (age: 2 months, aggregate grain size: 20 mm, plate thickness: 60 m)
When a force of 10 kg was applied to the m) and a drilling operation was performed, cutting chips were efficiently discharged as in Example 1, and dry continuous drilling was performed at an average drilling speed of 60 mm / min. Also,
It is 74 times (total 4
It was confirmed that a drilling work of 400 mm) was possible.

Comparative Example 1 A diamond grindstone having the same shape as in Example 2 was brazed and joined to the tip end of a steel body of the same twist drill type, and the diamond grindstone was slit-shaped with a width of 1.0 mm around the rotation axis. Although a vertical groove was formed, a dry diamond drill bit having a structure in which a slit-shaped vertical groove passing through a rotary shaft was not installed in a steel body was manufactured. When this diamond drill bit was used to carry out drilling work under the same conditions as in Example 2, the core of the work material hits the tip of the steel body and smooth discharge cannot be performed, which results in cutting resistance and drilling. The speed dropped below 5 mm / min. As a result of continuing the boring work, the heat storage of the cutting edge increased and the diamond abrasive grains deteriorated at a high temperature, making the boring impossible.

[0028]

As described above, by using the diamond drill bit for dry drilling of the present invention, various practical effects as described below are brought about. (1) 20 holes for hard and brittle materials such as stone and concrete
A hole having a relatively small diameter of less than or equal to mm can be drilled with an excellent drilling speed by an extremely simple operation. (2) The core of the cutting waste and cutting material can be effectively eliminated by the synergistic action of the slit-shaped vertical groove and the spiral groove, and the diamond grindstone at the cutting edge can be used until it is completely worn. The drilling work can be continued continuously for a long time. (3) Since it is possible to omit the use of fluids such as water and processing liquids during drilling work, there is no need for setup or special equipment before work,
Moreover, since the work environment is not polluted, it is easy to clean up after the work. (4) Since there is no need to use a vibration drill or the like, there is no concern about noise pollution, and worker fatigue can be reduced. (5) Since it can be easily carried out only by fitting it into a normal rotary tool, it is possible to easily carry out drilling work even in high places or in narrow work spaces.

[Brief description of drawings]

FIG. 1 is a partially cutaway vertical sectional view illustrating a diamond drill bit for dry drilling according to the present invention.

FIG. 2 is a plan view of the tip of FIG.

3 is a cross-sectional view taken along the line AA of FIG.

[Explanation of symbols] 1 body 2 spiral groove 3 diamond whetstone 4 vertical grooves 5 Tip slope 6 axis of rotation

─────────────────────────────────────────────────── ─── Continuation of the front page (56) Reference JP-A-1-206004 (JP, A) JP-A-4-228796 (JP, A) JP-A-63-239007 (JP, A) JP-A-3- 161280 (JP, A) Actual opening Sho 52-88776 (JP, U) Actual opening 3-96112 (JP, U) Actual opening 3-62758 (JP, U) Actual opening 3-47711 (JP, U) Actual development flat 2-117826 (JP, U) Actual development flat 2-335676 (JP, U) Actual development flat 1-101766 (JP, U) (58) Fields investigated (Int.Cl. ⁷ , DB name) B28D 1/14 B24D 7/18

Claims (4)

(57) [Claims] 1. A diamond drill bit for dry drilling, having a structure in which a diamond grindstone is integrally connected to a tip end portion of a body provided with a spiral groove along the outer circumference in the axial direction, wherein the cutting edge shape of the diamond grindstone is At least one longitudinal groove that is formed in a truncated cone shape with a diameter reduced from the surface connecting with the body toward the tip, reaches the body rotation axis from the tip tip surface including the rotation axis of the diamond grindstone, and communicates with the spiral groove. A diamond drill bit for dry drilling, which is characterized by being formed. 2. The diamond drill bit for dry drilling according to claim 1, wherein the width of the vertical groove is in the range of 1 mm or more and not exceeding 5 mm. 3. The diamond drill bit for dry drilling according to claim 1 or 2, wherein the maximum outer diameter of the diamond grindstone is 20 mm, and the outer diameter of the body is 98% or less. 4. The diamond drill bit for dry drilling according to claim 1, 2 or 3, wherein the frusto-conical inclination angle forming the cutting edge of the diamond grindstone is 70 to 30 ° with respect to the rotation axis.