JP3097356B2 - Manufacturing method of drill bit - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a drill bit used for a purpose such as forming a circular through hole in a concrete wall.

[0002]

2. Description of the Related Art A drill bit of this type is fixed to a cylindrical bit main body, a shaft coaxially provided on the base end side of the bit main body, and a constant pitch in a circumferential direction to a distal end of the bit main body. And a plurality of abrasive grain layer segments, and the shaft portion is connected to a driving device. Then, while the main bit is rotated by the driving device, the material is pressed against a work material such as a concrete wall, thereby cutting the work material with the abrasive grain layer segment to form a through hole.

[0003]

However, the conventional perforated bit has a disadvantage that the sharpness of the abrasive grain layer segment is reduced and clogging is apt to occur. Heretofore, the drilling operation has conventionally been performed by a wet method using a grinding fluid. However, since the grinding fluid contaminates the surroundings, there is an increasing demand for dry drilling in recent years. In that case, there is a problem that clogging is more severe because no grinding fluid is used.

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a method for manufacturing a perforated bit which can prevent clogging of an abrasive grain layer segment and can always maintain sharpness.

[0005]

[0006]

A method of manufacturing a drill bit according to the present invention includes all of the following steps. (A) a step of mixing a metal binder powder and superabrasive grains and compacting them to form a number of segment compacts. (B) a step of arranging the segment compacts in the annular cavity of the press die at intervals in the circumferential direction, and filling the gaps between the segment compacts in the cavity with metal powder; (C) The filled metal powder and the segment compact are integrally compacted and hot pressed to form an abrasive grain segment having a density ratio of 90% or more and an adjacent abrasive grain layer. A step of integrally forming a porous crosslinked portion having a density ratio of 60 to 80% between the segments to obtain an annular abrasive grain body as a whole. (D) a step of shaping the abrasive layer body and fixing it coaxially to an end face of a cylindrical bit body.

[0007]

According to such a manufacturing method, a cylindrical vial is formed.
The coaxial body is provided coaxially with the
The hollow shaft and the tip of the bit body
It has a large number of abrasive layer segments fixed at intervals.
The abrasive layer segment separates the superabrasive particles into the metal binder.
A sintered body with a density ratio of 90% or more
Porosity with a density ratio of 60-80% between the granular layer segments
Porous cross-sections made of porous metal sintered body are formed.
The tip surface of the porous bridging part is the tip of each abrasive grain layer segment.
It is possible to manufacture drilling bits continuously with the machined surface.
Wear. And to use such a drill bit,
The drilling bit is rotated around the axis, and the free abrasive grains are continuously supplied through the shaft of the bit body while pressing the tip against the work material. Then, the free abrasive grains supplied into the bit main body penetrate into the gap between the abrasive layer segment and the porous bridge portion and the work material. Since the tip surface of the bridge portion and the ground surface of the abrasive layer segment are flush with each other, the loose abrasive particles that have entered roll along the gap between these surfaces and the work material, and the abrasive particles Effectively dress layer segments.

Since the crosslinked portion is formed of a porous sintered body which is more liable to wear than the abrasive grain layer segments, the abrasive grains always wear slightly faster than the abrasive grain layer segments due to free abrasive grains, and the abrasive grain segment is cut. Does not hinder penetration into the material. As a result, the abrasive layer segments are sharpened by loose abrasive grains while grinding the work material, so that the sharpness is always maintained well, the discharge of the chips is enhanced, and the grinding is performed over a long period of time. Efficiency is obtained.

On the other hand, according to the method for manufacturing a drill bit according to the present invention, it is possible to form the abrasive grain layer segments and the porous cross-linking portions at an appropriate density ratio, and furthermore, the bonding strength and the forming dimensions of each other. High accuracy can be ensured. Therefore, a drill bit that can maintain good sharpness over a long period of time can be easily manufactured.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 shows a manufacturing method according to the present invention.
It is a vertical sectional view showing an example of a boring bits. In the figure, reference numeral 1 denotes a cylindrical bit body, and a cylindrical shaft 2 is formed coaxially at one end. On the other end surface of the bit main body 1, a large number of arc-shaped abrasive grain layer segments 3 are fixed in a line at regular intervals in the circumferential direction and fixed between the abrasive grain layer segments 3. As shown in FIG. 3 and FIG. 3, the porous bridging portion 4 which is a feature of the present invention is formed integrally with the abrasive grain layer segment 3. The width of the abrasive grain layer segment 3 is larger than the thickness of the bit main body 1 as shown in FIG. 1, and the center lines of the abrasive grain layer segment 3 and the bit main body 1 in the width direction coincide.

The abrasive layer segment 3 is made of diamond or carbon.
It is produced by mixing superabrasive grains such as BN with a metal binder powder, compacting and hot pressing.

The tip surface of each porous bridging portion 4 needs to be continuous with the ground surface of each adjacent abrasive grain layer segment 3. In this example, the width of the porous bridging portion 4 is further increased. Is the same as the width of the abrasive grain layer segment 3. The width of the abrasive layer segment 3 and the width of the porous bridging portion 4 do not necessarily have to be the same, and the width of the porous bridging portion 4 is
Even if the width is smaller than the width, the effect of the present invention can be obtained.

The porous bridging portion 4 is made of a porous metal sintered body having a smaller density ratio than the metal binder constituting the abrasive grain layer segments 3. The porous bridge portion 4 is softer than the metal binder. It is desirable to be formed of the same metal as the metal bonding material or a softer metal. As a specific material, Cu, Zn, Sn, Al, Co, Ag, Ni, an alloy thereof, or the like is preferable for both the metal binder and the porous cross-linking portion 4.

Preferably, the density ratio of the abrasive grain layer segments 3 is 90% or more, and the density ratio of the porous cross-linked portions 4 is about 60 to 80%. If the density ratio of the abrasive layer segments 3 is less than 90%, sufficient sharpness cannot be obtained. On the other hand, if the density ratio of the porous cross-linked portion 4 is less than 60%, the cross-linked portion 4 is excessively worn and the effect of uniformly distributing the abrasive grains is poor, and conversely, 80%
If it is larger, the bridging portion 4 is less likely to be worn and hinders the abrasive layer segment 3 from biting into the work material.

Next, an embodiment of a method for manufacturing the above-mentioned perforated bit will be described. First, the metal binder powder and the superabrasives are uniformly mixed at a predetermined ratio, and are compacted in a press mold to form a large number of segment compacts 3A. The density ratio at this point is set low. The pressing temperature is normal temperature or lower than the sintering temperature, and sintering is not performed at this time.
The shape of the segment compact in plan view is substantially equal to that of the abrasive grain layer segment 3, and the height is larger than that of the abrasive grain layer segment 3. This is because the density ratio is small.

Next, as shown in FIG. 4, the arc-shaped segment molded bodies 3A are arranged in the annular cavity C between the hot press dies P1 and P2 at intervals in the circumferential direction. The metal powder 4A is filled in the gap between the segment molded bodies 3A in C. Metal powder 4A
Is set higher than the segment molded body 3A. However, when the density ratio of the segment molded body 3A is low, it is possible to fill up to the same height as the segment molded body 3A as shown in FIG. If necessary, a portion of the press dies P1 and P2 for pressing the segment molded body 3A and a portion for pressing the metal powder 4A are separated from each other,
By separately driving, the filling height of the metal powder 4A and the molding density ratio may be arbitrarily changed.

After the segment compact 3A and the metal powder 4A are filled between the press dies P1 and P2, they are hot-pressed to form an abrasive layer S as shown in FIG. The hot pressing conditions are such that the molding density ratio of the metal powder 4A is about 60 to 80% as described above. The hot press is used because the diameter of the abrasive grain layer body S is reduced by the normal sintering method, and it becomes difficult to accurately position the abrasive grain layer body S on the end face of the bit body 1 and fix the abrasive grain layer body S. It is.

In this embodiment, as shown in FIG. 5, the density ratio of each of the abrasive grain layer segments 3 is higher than that of the porous bridging portion 4 (the density ratio becomes substantially the same as that of the abrasive grain layer segments 3). 3) The portions 5 are formed, and these portions 5 may be removed by truing (shaping) or may be left as a joint to the bit body 1.

The abrasive layer body S is trued as required and fixed coaxially to the end face of the bit body 1. As the fixing method, various welding methods are suitable from the viewpoint of heat dissipation and strength.

Next, a perforation method using the perforation bit will be described. In this method, first, while rotating the drill bit 1 as shown in FIG. 1, the cutting is started by pressing the drill bit 1 against the work material W, and at the same time, loose abrasive grains are introduced into the bit body 1 through the hollow shaft portion 2 of the bit body 1. Supply.

As the loose abrasive, diamond, CBN
Super-abrasive grains such as, for example, or general abrasive grains such as SiO and Al ₂ O ₃ can be used, and are supplied in a powder state or in a slurry state after being added to a commonly used grinding fluid. The average grain size of the free abrasive grains is not necessarily limited, but is preferably about 100 to 30% of the average grain size of the abrasive grains in the abrasive grain layer segment 3 in order to enhance the dressing effect.

A part of the loose abrasive particles supplied into the bit body 1 enters the interface between the abrasive layer layer 3 and the porous bridge 4 and the work material W, and wears the porous bridge 4 appropriately. At the same time, the binder phase exposed on the grinding surface of the abrasive grain layer segment 3 is shaved, and the superabrasive grains buried in the abrasive grain layer segment 3 are bladed to sharpen the abrasive grain layer segment 3. The loose abrasive used for the dressing is sequentially discharged to the outside of the drill bit as the drill bit rotates, and the chips are also carried along therewith. Since there are countless irregularities on the surface of the porous bridge portion 4, chips are swept out by these irregularities, and the chip discharging property is extremely good. Therefore, according to the drill bit having the above-described configuration, the sharpening action described above always maintains good sharpness of the abrasive grain layer segment 3 and also enhances the ability to discharge cutting chips, thereby improving the quality over a long period of time. A stable sharpness is obtained.

On the other hand, if the porous bridging portions 4 do not exist between the abrasive grain layer segments 3, loose abrasive grains pass through the gaps between the respective abrasive grain layer segments 3 to the outer peripheral side,
It is difficult to be introduced into the interface between the abrasive grain layer segment 3 and the work material, and the sharpening effect by the free abrasive grains is significantly reduced.

Next, FIG. 7 shows a second embodiment of the perforated bit. In this example, the end face of each abrasive grain layer segment 3 on the tip end side in the bit rotation direction becomes more forward in the rotation direction as it goes toward the inner periphery of the bit. It is characterized in that the inclined surface 6 is located.
Other configurations are the same as those of the above embodiment.

Since the tip of the abrasive grain layer segment 3 always projects slightly beyond the porous bridging portion 4, free abrasive grains supplied from the inner peripheral side of the bit main body 1 are removed by the rotation of the drill bit. The abrasive layer segment 3 is dressed while being gradually transferred to the outer peripheral side by the edge of the inclined surface 6 of the granular layer segment 3. In the process, the generated chips are also transported to the outer peripheral side of the bit together with the free abrasive grains, so that the chip discharge performance is further improved as compared with the above embodiment, and the effect of preventing the abrasive grain layer segments 3 from being clogged is improved. Has the advantage of being enhanced.

FIG. 8 shows a third embodiment of the drill bit. In this embodiment, the front end face 7 in the rotational direction of all the abrasive grain layer segments 3 is formed in a convex V-shape, and the rear end face 8 is formed in a concave V-shape. It is characterized by the following. When formed in this manner, the abrasive grain layer segment 3
And the bonding strength between the porous bridge 4 and
It is possible to reduce the risk of the porous bridge 4 falling off.

The same effect of improving the bonding strength can be obtained even if the unevenness of the abrasive grain layer segment 3 before and after the rotation direction is reversed, or both ends are convex or both ends are concave.
Further, by forming a large number of minute irregularities on the front end face and the rear end face of the abrasive grain layer segment 3 by various blasting methods or the like, it is also possible to increase the bonding strength between the abrasive grain layer segment 3 and the porous bridge portion 4. is there.

It is also effective to form the bit body 1 with a damping material for the purpose of improving the damping effect. The following are typical vibration damping materials that have been put to practical use. Composite damping alloys such as flaky graphite cast iron and Zl-Al alloys Dislocation damping alloys such as pure Mg and Mg-0.6Zr Mn-37Cu-4Al-3Fe-2Ni, Cu-
45Mn-2Al, 50Ni-50Ti, Cu-14A
Twin type damping alloys such as 1-4Ni, etc. Composite damping materials such as resin layer sandwich steel sheets Ferromagnetic damping alloys

Among the above, the ferromagnetic damping alloy has the advantage that the loss coefficient is less reduced at high temperatures than other damping materials because the frequency dependence of the loss coefficient is small. Examples of this type of ferromagnetic damping alloy include Fe-Al-Si alloy Fe-0.1C-12Cr-1Al alloy Fe-12Cr-2Al alloy Fe-12Cr-2Al-3Mo alloy Co-22Ni -2Ti-0.5Al alloy.

According to the experiments of the present inventors, when the bit body is formed of a normal steel material, the noise amount is 95 dB in decibel A.
Whereas the material of the bit body was changed to NKK Corporation's product name "NKK SERENA" (2.5% Al
It has been confirmed that the change to -0.53% Si-balance Fe) reduces to 80 phones. If the vibration of the bit body is reduced, the bite of the abrasive grain layer segment into the work material is stabilized, and the effect of the present invention is further enhanced.

[0031]

As described in the foregoing, manufactured depending on the present invention
According to the drill bit to be manufactured, the drill bit is rotated around the axis, and the free abrasive grains are continuously supplied through the shaft portion of the bit body while pressing the tip of the drill bit against the work material. The free abrasive grains supplied to the gap penetrate into the gap between the abrasive layer segment and the porous bridging portion and the work material. Since the tip surface of the bridge portion and the ground surface of the abrasive layer segment are flush with each other, the loose abrasive particles that have entered roll along the gap between these surfaces and the work material, and the abrasive particles Effectively dress layer segments.

Since the bridging portion is formed of a porous sintered body that is more easily worn than the abrasive layer segment, the abrasive portion is always worn slightly earlier than the abrasive layer segment by free abrasive grains, and the abrasive layer segment is cut. Does not hinder penetration into the material. As a result, the abrasive layer segments are sharpened by the free abrasive grains while grinding the work material, and the sharpness is always maintained well. In addition, since there are countless irregularities on the tip surface of the porous bridge portion, chips are swept out by these irregularities,
The chip dischargeability is also enhanced, and good grinding efficiency can be obtained over a long period of time.

On the other hand, according to the method for manufacturing a perforated bit according to the present invention, it is possible to form the abrasive grain layer segment and the porous cross-linking portion at an appropriate density ratio, and furthermore, the bonding strength and the forming dimension of each other. High accuracy can be ensured. Therefore, a drill bit that can maintain good sharpness over a long period of time can be easily manufactured.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view showing an example of a drill bit and a drilling method manufactured by a manufacturing method according to the present invention.

FIG. 2 is a bottom view of an abrasive grain layer segment and a porous bridge portion of the drill bit.

FIG. 3 is a side view of the abrasive grain layer segment and a porous bridge portion.

FIG. 4 is a longitudinal sectional view showing one embodiment of a method for manufacturing a drill bit according to the present invention.

FIG. 5 is a side view showing a formed abrasive grain layer body.

FIG. 6 is a longitudinal sectional view showing another embodiment of the method of manufacturing a drill bit.

FIG. 7 is a bottom view of an abrasive grain layer segment and a porous bridge portion of a drill bit according to another example of the present invention.

FIG. 8 is a bottom view of an abrasive grain layer segment and a porous bridging portion of still another example of a perforated bit.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Bit main body 2 Shaft part 3 Abrasive layer segment 3A Segment compact 4 Porous bridge part 4A Metal powder 5 High density ratio part S Abrasive layer body 6,7,8 End face of abrasive layer segment P1, P2 Hot press type

Continuation of the front page (58) Field surveyed (Int. Cl. ⁷ , DB name) B28D 1/14 B23B 51/04 B24D 7/06 B24D 7/18

Claims (1)

(57) [Claims] 1. A method comprising the following steps :
Manufacturing method of drill bit. (A) Mixing metal binder powder and superabrasives, and compacting
Forming a large number of segment compacts. (B) Pressing the segment molded body into a press-shaped annular cavity
With a circumferential gap in the tee and
Fill the gap between each segment compact with metal powder
Process. (C) filling the filled metal powder and segment compact
Integrally compacted and hot pressed to produce segments
When the compact is an abrasive layer segment with a density ratio of 90% or more
In both cases, the density ratio between adjacent abrasive grain layer segments
60-80% of porous cross-links are integrally formed, and as a whole
A step of obtaining an annular abrasive layer body; (D) A cylindrical bit body after shaping the abrasive layer body
Fixing coaxially to the end face of