JPH0698620B2 - Rotary drilling tool - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial field of application] The present invention relates to stone, concrete, magnetic tile, glass,
It relates to a rotary tool used for drilling hard non-metallic materials such as ceramics.

[Conventional technology]

For drilling hard non-metallic materials such as concrete and ceramics, for example, a rotary drilling tool as shown in FIG. 3 is used.

A drive member driven by a power source or an air source is built in the tool main body 2, and the hollow rotary shaft 8 is rotationally driven by this drive member. The hollow rotary shaft 8 has
A rotary drill 18 having an axial through hole 14 is mounted, and a cutting blade 16 formed by sintering diamond grains is fixed to the tip of the rotary drill 18. The cutting blade 16 is formed with an outlet 16a for cooling fluid, which is in communication with the flow hole 14 of the rotary drill 18.

A rotary flow channel system 20 is formed by the hollow rotary shaft 8 and the rotary drill 18, and a fixed flow channel system 26 is formed by a supply pipe 25 that guides a cooling fluid supplied from the outside of the tool body 2 to the inside. . The rotary flow channel system 20 and the fixed flow channel system 26 are connected so as to be able to guide the fluid. The cooling fluid guided from the fixed flow channel system 26 is ejected from the ejection port 16a of the cutting member 16 via the rotary flow channel system 20. Then, the jetting of the cooling fluid suppresses wear of the cutting blade 16 due to frictional heat.

As described above, this type of rotary drilling tool basically requires a technique for connecting the fluid between the rotary flow channel system and the fixed flow channel system so that the fluid can be guided. In the 201908 publication, a spiral groove is formed on the outer peripheral surface of a hollow rotary shaft on which a rotary drill is mounted, and one end side of this spiral groove is provided at a water supply port as a fixed flow path system of a water supply unit body surrounding the hollow rotary shaft. In addition, a structure has been proposed in which the other end is exposed to a small hole formed in the radial direction of the hollow rotary shaft so that the rotary drill and the water supply port communicate with each other. In addition, JP-A-60-26260
In the publication No. 8, a radial passage opening in the radial direction is formed in the hollow rotary shaft, and the radial passage is fixed to an outer cylinder surrounding the hollow rotary shaft via a swivel space to a pressure supply hose as a fixed flow passage system. A structure that allows communication is proposed. As described above, the connection between the rotary flow channel system and the fixed flow channel system is basically the one in which the fixed flow channel system is generally orthogonal to the flow channel axis of the rotary flow channel system, although there is a structural difference. It is structured to communicate from the direction.

[Problems to be Solved by the Invention]

By the way, in this type of drilling tool, water or air is adopted as the cooling fluid, but in the case of water, there is a problem that the surroundings of the work area are contaminated by suspended water due to cutting chips, and in the case of air Has the drawback of low cooling efficiency.
Therefore, a so-called mist obtained by atomizing a liquid such as water is considered to be an optimal fluid from the viewpoint of a compromise between the advantage of water with high cooling efficiency and the advantage of air that does not cause the pollution problem due to wastewater.

However, in the structure as described above, the fixed flow channel system is connected to the rotary flow channel system that rotates at a high speed at right angles to the flow channel axis, so that the kinetic energy of the fluid due to the bending of the flow channel is The decrease is unavoidable, and with this type of drilling tool, the internal pressure of the rotary flow path system also rises to a certain extent due to the narrow discharge space of the fluid during drilling. There is a problem that most of the mist disappears due to stagnation inside the path system and the cutting blade is cooled so that an appropriate atomization state cannot be maintained.

In addition, the centrifugal force generated by the high-speed rotation of the rotary flow path system,
Since it acts in the direction to prevent the introduction of mist from the fixed flow path system to the rotary flow path system in the radial direction, there is also the problem that the mist tends to stagnant and disappear at the part where both flow path systems are in communication. Was there.

On the other hand, Japanese Utility Model Laid-Open No. 62-201642 proposes a drilling tool that supplies air to a cutting blade by connecting a fixed flow channel system and a rotary flow channel system on the same axis line. A rotary joint filled with grease is used at the connection with the flow path system, and since the gap between the fixed side and the rotating side is sealed by grease, a reliable sealing effect is obtained with fluid containing water such as mist. It could not be expected and could not be used because there is a risk that mist may flow out into the tool body and cause electric leakage.

The present invention has been made in view of the above-mentioned problems of the prior art, and efficiently cuts a cutting blade without causing stagnation of mist in a communicating portion between a fixed flow channel system and a rotary flow channel system. A main object of the present invention is to provide a rotary drilling tool that can be cooled and that does not allow mist to leak into the tool body.

[Means for Solving the Problems]

This invention, in order to solve the above-mentioned problems, has a rotary drill having an axial flow hole and a cutting blade at the tip, and a rotary hole in which this rotary drill is attached to the front end and communicates with the flow hole in the axial direction. A hollow rotary shaft that is pierced through and is rotatably driven by the tool main body, guides the mist supported by the tool main body and supplied from the outside to the inside of the tool main body, and aligns the axis line with the rear end surface of the hollow rotary shaft. A feed pipe whose front end faces are opposed to each other, a rotary connector provided on the outer periphery of the rear end of the hollow rotary shaft, and a fixed connector provided on the outer periphery of the front end of the supply pipe so as to face the rotary connector. A seal member arranged between the facing surfaces of the connection body and the fixed connection body to prevent leakage of mist from the gap between the supply pipe and the hollow rotary shaft, and a thrust bearing interposed between the rotation connection body and the fixed connection body. With and A.

[Action]

The mist supplied from the outside of the tool body is guided from the supply pipe into the tool body, passes through the flow hole of the hollow rotary shaft from the rear end of the hollow rotary shaft, and is then supplied to the cutting blade from the flow hole of the rotary drill.

The rotary connector provided on the outer periphery of the rear end of the hollow rotary shaft and the fixed connector provided on the outer periphery of the front end of the supply pipe are arranged to face each other,
The sealing member arranged between the facing surfaces of both the connecting bodies prevents the mist introduced from the supply pipe into the hollow shaft from leaking to the outside.

Further, the thrust bearing interposed between the two connecting bodies prevents the seal member from being subjected to an excessive pressure contact force.

〔Example〕

 1 and 2 show an embodiment of the present invention.

The same parts as those in the conventional example are indicated by the same reference numerals.

Inside the tool body 2, a hollow rotary shaft 8 having an axial flow hole 4 on the rear half side and a tapered mounting hole 6 communicating with the flow hole 4 on the front half side is a radial ball bearing 10.
It is rotatably installed via 12. A rotary drill 18 having an axial flow hole 14 and a cutting blade 16 formed by sintering diamond grains at the tip is fixed to the front end of the hollow rotary shaft by a mounting hole 6.

The hollow rotary shaft 8 and the rotary drill 18 form a rotary flow path system 20. Further, a supply pipe 24 having an open end on the upper side of the tool body 2 and having an axial flow hole 22 is supplied from outside the tool body 2 by means of a sprayer or the like to cool the cutting blade 16. A fixed flow channel system 26 for guiding the mist M to the inside is formed. The supply pipe 24 is supported by a bearing 42 in the tool body 2 at a position rearward of the hollow rotary shaft 8. The rotary flow channel system 20 and the fixed flow channel system 26 are connected by a fixed connector 27 and a rotary connector 29.

A gear 28 is fixed to the rear half of the hollow rotary shaft 8.
A driven shaft 30, which is driven to rotate by a drive source (not shown), is rotatably installed parallel to the lower side of the hollow rotary shaft 8 via ball bearings 32 and 34. A gear 36 that meshes with the gear 28 of the hollow rotary shaft 8 is fixed to one end of the driven shaft 30, and a gear 38 that meshes with the drive gear of the drive source is fixed to the other end. Therefore, the hollow rotary shaft 8 is rotationally driven via the driven shaft 30 by the operation of the drive source. A taper shank portion 18a corresponding to the mounting hole 6 is formed at the rear end portion of the rotary drill 18, and the hollow rotary shaft 8 is provided at the end portion of the taper shank portion 18a and the back portion of the mounting hole 6, respectively. A male screw portion 18b and a female screw portion 6a that are screwed in the reverse rotation direction are formed. As a result, the rotary drill 18 is mounted on the hollow rotary shaft 8 in a state in which the rotary drill 18 is prevented from idling and falling off.

Between the inner peripheral surface of the front end portion of the tool body 2 and the outer peripheral surface of the hollow rotary shaft 8 on the front end side, a sealing member 39 for preventing the intrusion of cutting chips into the tool body 2 is installed.

The fixed connection body 27 is press-fitted to the outer circumference of the front end of the supply pipe 24, while
The rotary connection body 29 is press-fitted into the outer periphery of the rear end of the hollow rotary shaft 8 and is partially fitted to each other and arranged to face each other.

As shown in FIG. 2 (A), an annular convex portion 29b is formed in the rotary connector 29 so as to be continuous with the press-fitting hole 29a for the hollow rotary shaft 8, and an annular concave portion 29c is formed outside the annular convex portion 29b. An annular convex portion 29d is formed so as to project short in the axial direction.

On the other hand, as shown in FIG. 2B, the fixed connection body 27 is formed with a recess 27b that is connected to the press-fitting hole 27a for the supply pipe 24 and fits into the annular projection 29b, and is formed around this recess 27b. The annular convex portion 27c is fitted with the annular concave portion 29c
An annular recess 27d into which 29d is fitted is formed.

Between the inner facing surfaces of the rotary connector 29 and the fixed connector 27,
An O-ring 52 is installed as a seal member.

The O-ring 52 is fitted in the annular recess 29c of the rotary connector 29,
It is pressed by the annular projections 27c of the fixed connection body 27 that face each other.

Further, a thrust bearing 54 is installed between the outer facing surfaces of these connecting bodies 27, 29.

The thrust bearing 54 is fitted in the annular recess 27d of the fixed connection body 27, and is brought into contact with the end surface of the annular projection 29d of the rotating connection body 29 which faces the thrust connection.

The rotary connector 29 is positioned by the spacer member 58 such that the end surface of the rotary connector 29 facing the fixed connector 27 is slightly projected from the rear end surface of the hollow rotary shaft 8.

〔The invention's effect〕

According to this invention, since the mist is introduced into the flow hole of the rotating hollow rotating shaft through the supplying pipe whose front end face is aligned with the axis of the hollow rotating shaft, the front end face is opposed to the hollow pipe. There is no loss of kinetic energy because the direction of mist flow does not change when flowing into the rotating shaft, and the introduction of mist from the supply pipe side to the hollow rotating shaft side is hindered by the centrifugal force generated by the high speed rotation of the hollow rotating shaft. Since it is not generated, it is possible to prevent the loss due to the retention of the mist, and the mist can be efficiently supplied to the cutting blade.

As a result, it is possible to practically apply the mist as the cooling fluid, which suppresses the wear of the cutting blade, reduces the working cost, and improves the workability.

In addition, a seal member for preventing leakage from the gap between the supply pipe and the hollow rotary shaft is arranged between the facing surfaces of the rotary connecting body and the fixed connecting body, and the thrust bearing is interposed between both connecting bodies. Therefore, it is possible to prevent an axial load applied between these connecting bodies from being applied to the thrust bearing and an excessive contact force being applied to the seal member.

As a result, the wear of the seal member is suppressed, so that the sealing performance of the seal member can be maintained for a long period of time, leakage of mist into the tool body can be prevented from an electric leakage accident, and reliability can be improved.

[Brief description of drawings]

FIG. 1 is a schematic vertical sectional view of a drilling tool according to an embodiment of the present invention, FIG. 2 is a sectional view of a fixed connection body and a rotary connection body, and FIG.
The figure is a schematic perspective view of a conventional drilling tool. 2 ... Tool body, 4, 14, 22 ... Flow hole, 8 ... Hollow rotary shaft 16 ... Cutting blade, 18 ... Rotary drill, 20 ... Rotary flow path system 24 ... Supply pipe, 26 ... Fixed flow path system, 27 …… Fixed connector 29 …… Rotary connector, 52 …… Seal member 54 …… Thrust bearing

Claims (1)

[Claims] 1. A rotary drill 18 having an axial flow hole 14 and a cutting blade 16 at the tip, and a rotary hole 18 attached to the front end of the rotary drill 18 and communicating with the flow hole 14 axially penetrates. And the tool body 2
The hollow rotary shaft 8 supported by the tool and driven to rotate, and the mist supported by the tool body 2 and supplied from the outside are guided to the inside of the tool body 2, and the hollow rotary shaft 8 has its axis aligned with the rear end surface of the front end surface. Are arranged to face each other, a rotary connector 29 is provided on the outer periphery of the rear end of the hollow rotary shaft 8, and a fixed connector 27 is provided on the outer periphery of the front end of the supply pipe 24 so as to face the rotary connector 29. A seal member 52 disposed between the facing surfaces of the rotary connector 29 and the fixed connector 27 to prevent the mist from leaking from the gap between the supply pipe 24 and the hollow rotary shaft 8, and the rotary connector 29 and the fixed connector. And a thrust bearing 54 interposed between the rotary drilling tool and the thrust bearing.