JPH09201705A - Center - Google Patents

Abstract

PROBLEM TO BE SOLVED: To accurately joint a PCD tip without positional deviation while maintaining joining force of brazing by providing a plurality of grooves for guiding brazing materials in the outer peripheral busbar direction of the PCD tip. SOLUTION: In joining of a PCD tip 2 to a recessed part 1a of a shank 1, active metallic brazing materials are filled in the bottom part of a recessed part 3a of a metallic member 3. A PCD tip 2 is inserted into the recessed part 3a of the metallic member 3 and then heated to the melting temperature of the brazing material, and the brazing materials are molten. The active metallic brazing materials poured into the recessed part 3a are raised in grooves G when the PCD tip 2 is seated on the recessed part 3a by applying load from above, and the raised active metallic brazing materials are allowed to flow out to the outer peripheral surface and solidified. After the PCD tip 2 is joined to the metallic member 3, the metallic member 3 is connected to the recessed part 1a of the shank 1 by a brazing method. Therefore, the accurate center having no positional deviation can be provided while maintaining joining force of brazing.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a center used for a lathe, a cylindrical grinder or the like and used as a centering jig for a work material.

[0002]

2. Description of the Related Art In lathes and cylindrical grinders capable of various processes such as grinding and drilling, it is important to accurately center the workpiece. A metal center formed of a super hard metal such as is used. The tip of the center is very likely to wear because a strong force is concentrated during cutting or grinding, and this wear of the tip of the center causes displacement of the center position of the rotating body.
This is also a major factor that reduces the processing accuracy. For example, in the case of a center in which a cemented carbide is attached to the tip of a shank, re-polishing is required about every 10 days in order to maintain good processing accuracy with a roundness of 3 μm or more.

As a measure against this, as described in 8.4.2 Machine Tool Abrasion-Resistant Tools (P646-647) of "New Machining Tool Encyclopedia" published by Encyclopedia Publishing Center, Industrial Research Institute Co., Ltd. A convex center in which a convex cemented carbide member formed by a diamond sintered body (hereinafter referred to as PCD) chip is fitted at the tip, and a concave notch is provided at the tip of the shank. A concave center in which a super hard member made of a PCD chip is attached to the above has been put into practical use.

Conventionally, the PCD tip is attached to such a steel shank by a caulking method of mechanically fixing,
Also, a sintering method using metal powder is adopted. However, in such a caulking method or a sintering method using a metal powder, it is difficult to chemically bond the PCD chip and the bonding base material to each other, so that it is difficult to secure sufficient bonding strength, and therefore, in use. There is a problem that the PCD chip is easily detached. Further, particularly in the case of the caulking method, it is extremely difficult to accurately set the center position of the PCD chip, which is a major impediment factor for popularizing the center using the PCD chip excellent in abrasion resistance. ing.

In order to solve this, it is considered to use a so-called brazing method used for joining diamond tools and the like. This brazing method is a method in which an alloy having a low melting point, such as silver brazing, is melted to bond the target metals together without melting the base metal in the bonded portion.

[0006]

To mount the PCD chip on the shank by the brazing method, a molten active metal wax or the like is poured into a recess for mounting the PCD chip formed at the tip of the shank, and the molten metal brazed metal is poured into the recess. By dropping the PCD chip processed into a predetermined shape, the brazing material is solidified between the outer peripheral surface of the PCD chip and the inner peripheral surface of the recess of the shank to bond the two.

In order to have a strong adhesive force, it is necessary to turn the molten brazing material not only on the bottom surface of the cylindrical PCD chip but also on the entire outer peripheral surface. In order to spread the brazing material, at least 0.1 is provided between the PCD tip and the shank recess as a brazing material passage.
It is necessary to provide a clearance of ~ 0.2 mm.

On the other hand, as described above, it is important that the center of the centering jig has a particularly accurate center position. In the conventional method, however, a wide area for the brazing material to flow is provided. PC is required because clearance is required
Due to the misalignment when dropping the D chip into the recess, PCD
The center position of the chip is displaced by up to 0.2 mm.

Although such a deviation of the center position of the PCD chip can be eliminated to some extent by finish polishing, the deviation is completely caused because the area where the PCD chip and the grindstone contact each other changes during one rotation. It is difficult to remove.

The problem to be solved by the present invention is to provide an accurate P with no positional deviation while maintaining the joining force by the conventional brazing.
It is to provide a bonding means for a CD chip.

[0011]

Means for Solving the Problems As a result of intensive research for solving the above problems, the present inventor has melted in the direction of the outer peripheral busbar of the PCD chip or in the direction of the inner peripheral busbar of the recess of the metal member for joining the PCD chip. By forming the groove for the brazing material to flow in, it is possible to reduce the clearance between the PCD chip and the inner periphery of the fitting hole of the base material while maintaining the flow of the brazing material to the side surface of the PCD chip. That is, the present invention has been completed and the present invention has been completed.

That is, according to the present invention, in the center where the convex PCD chip is fixed by brazing to the recess formed in the tip of the shank, the recess of the PCD chip outer peripheral bus line direction or the metal member for joining the PCD chip is formed. Is characterized in that a plurality of grooves for guiding the brazing material are formed in the inner peripheral bus direction.

The groove formed in the outer peripheral busbar direction of the PCD chip or in the inner peripheral busbar direction of the concave portion of the metal member allows the brazing material poured into the fitting hole when the chip is dropped into the shank or the fitting hole of the metal member. It escapes to the upper part, and acts to resist the surface tension of the brazing material and allow the chip to be accurately seated on the bottom surface of the fitting hole. Further, it is possible to increase the contact area between the brazing material and the outer peripheral surface of the chip or the inner peripheral surface of the fitting hole of the metal member, and obtain a good joining force. As a result, the clearance between the PCD chip and the inner periphery of the fitting hole, which was required to be about 0.2 mm in the past, can be narrowed to 0.1 mm or less.

Here, the groove is a commonly used cylindrical PCD chip having a diameter of 5 to 10 mm.
It is desirable to form at least four or more pieces with a width of 0.2 to 1.0 mm and a depth of 0.1 to 0.5 mm at equal intervals in the generatrix direction. If the grooves are not formed at equal intervals, the adhesive force will vary, and if the number of grooves is less than 4, the brazing material will not be able to sufficiently rotate to the peripheral surface. If the groove width is less than 0.2 mm, the brazing material will not rise, and if it exceeds 1.0 mm, misalignment will occur. Further, if the depth is less than 0.1 mm, the brazing material will not rise properly, and if it exceeds 0.5 mm, the PCD chip will be easily chipped.

Further, in a center in which a convex PCD chip is fixed by brazing in a recess formed at the tip of the shank, the equipment for making a vacuum or an inert gas atmosphere during brazing is downsized. Also, from the viewpoint of preventing the PCD chip from cracking due to heat during bonding, it is desirable to interpose a metal member for bonding the PCD chip between the shank and the PCD chip. This metal member is P
When the CD chip and the metal member are joined by a brazing material, it has an action of preventing cracking due to a difference in thermal expansion, and Kovar, molybdenum, cemented carbide, etc. can be used. Has almost the same coefficient of thermal expansion as the chip,
Kovar, which is an alloy of 53% iron, 28% nickel, and 18% cobalt, can be preferably used. Here, the PCD chip and the metal member are joined together by an active metal braze containing an active metal such as titanium or tantalum in an amount of 2 to 5% by weight of the silver braze, thereby forming a PCD chip.
The chip and the metal member can be chemically integrated.

Between the shank and the PCD tip, the PCD
In the case of interposing a metal member for joining chips, instead of forming a groove for guiding a brazing material in the PCD chip, a plurality of grooves can be formed in the inner peripheral generatrix direction of the recess of the metal member.

The formation of such a brazing material guide groove on a PCD chip or a metal member is performed by a conventionally known electric discharge machine, a method of grinding with a thin plate grindstone on a surface grinder, an end mill, a drill at a machining center. For example, a method of grooving the side surface can be adopted.

The center is manufactured by directly joining a PCD chip to a shank having a cylindrical fitting hole with an active metal solder, or by brazing an active metal to a metal member having a fitting hole with a PCD chip. Are joined together, and the metal member and the steel shank are joined together by ordinary silver brazing. Here, in the structure without the metal member, the PCD chip is apt to be cracked due to the difference in the coefficient of thermal expansion.

In the present invention, the groove for guiding the brazing material is formed in the outer peripheral bus bar direction of the PCD chip or in the inner peripheral bus bar direction of the concave portion of the metal member, so that the outer circumference of the chip and the inner circumference of the fitting hole of the base metal. The clearance with can be narrowed,
With a clearance of about 0.05 mm, the brazing material poured to the bottom of the base material fitting hole can be efficiently released to the upper part, and the PCD chip can be accurately seated on the bottom surface of the base material fitting hole. At that time, by forming the groove in the PCD chip or the metal member, the contact area between the inner peripheral surface of the PCD chip or the metal member and the brazing material is increased, and thereby good bonding strength can be maintained. Become.

[0020]

1 is a front view of a center showing an embodiment of the present invention, FIG. 2 is an enlarged sectional view of a portion A in FIG. 1, FIG. 3 is an exploded perspective view of a main portion, and FIG. It is a cross-sectional view of a PCD chip.

1 is a tapered shank made of steel,
2 is a diamond grain size 2 provided at the tip of the shank 1
It is a 5 μm PCD chip, has a cylindrical shape of φ10 × 15 ^L , and is formed with a tip angle θ of 60 to 90 °. As clearly shown in FIGS. 2 and 3, a cylindrical recess 1a is cut out at the tip of the shank 1, and a bottomed cylindrical metal member 3 is mounted in the recess 1a.

The metal member 3 is made of Kovar, the outer diameter of which is slightly smaller than the inner diameter of the recess 1a of the shank 1, and the recess 3a for accommodating the PCD chip 2 is formed above the metal member 3. .

The PCD chip 2 and the metal member 3 are joined together by an active metal braze 5 containing 2% by weight of titanium in a silver braze, and between the metal member 3 and the recess 1a of the shank 1 is a conventionally known silver braze. It is joined by 6.

Referring to FIGS. 3 and 4, the PCD chip 2 has a tip portion 2b which is sharpened at the tip of a cylindrical body 2a, and is equidistant in the outer peripheral generatrix direction of the body 2a. 8
The groove G of the book is formed. This groove G is for the PCD chip 2
The outer diameter D of the main body 2a is 10 mm, and the width W of the groove G is 0.4.
mm and the depth d is 0.2 mm. Further, the inner diameter of the cylindrical metal member 3 was 10.05 mm with a clearance of 0.025 mm from the outer diameter D10 mm of the main body 2a of the PCD chip 2. PCD chip 2
It is manufactured by filling a cylindrical capsule with diamond powder having an average particle size of 25 μm and sintering the cylindrical capsule at a temperature of 1500 ° C. and a pressure of 50,000 atm.

Next, with reference to FIG. 5, a method of manufacturing the above center will be described. PC to recess 1a of shank 1
First, as shown in FIG. 5A, the D chip 2 is joined as follows.
The active metal wax 5 was filled in the bottom of the recess 3 a of the metal member 3. Next, the PCD chip 2 was inserted into the recess 3a of the metal member 3 as shown in FIG. 5B, and then heated to the melting temperature of the brazing material to melt the brazing material as shown in FIG. 5C. At this time, by simultaneously applying a load from above, when the PCD chip 2 is seated in the recess 3a, the active metal braze 5 poured into the recess 3a rises in the groove G, and the raised active metal braze 5 is It flowed out to the outer peripheral surface and solidified. Note that these operations were performed in a vacuum of 10 ^-5 Torr or less because an active metal braze is used. After joining the PCD chip 2 to the metal member 3 in this way,
As shown in FIG. 5 (d), the metal member 3 is joined to the recess 1a of the shank 1 by a conventionally known brazing method.
The center shown in (e) is manufactured.

FIG. 6 is an exploded perspective view of a main part of a center according to another embodiment of the present invention. In the present embodiment, instead of forming the brazing material guiding groove G in the PCD chip 2 in the embodiment shown in FIG. 3, a plurality of brazing material guiding wires are formed in the inner peripheral generatrix direction of the recess 3a of the metal member 3. The groove Gm is formed.

In this embodiment, eight grooves Gm are formed at equal intervals in the inner peripheral generatrix direction of the recess 3a of the metal member 3. The inner diameter of the metal member 3 is the outer diameter D of the PCD chip 2.
The clearance of 0.025 mm is set to 10.05 mm for 10 mm, and the groove Gm is the groove G of the PCD chip 2.
Similarly, the width is 0.4 mm and the depth is 0.2 mm.

In the case of this embodiment, the effect of forming the groove is the same as that of forming the groove G in the PCD chip 2, while forming the groove Gm in the metal member 3 having a hardness lower than that of the PCD chip 2. Therefore, there is an advantage that processing for forming the groove is easy.

In the above description, the so-called convex center is described, but it is of course applicable to the concave center.

[0030]

According to the present invention, the following effects can be obtained.

(1) Bonding by brazing by forming a groove for guiding a brazing material in the direction of the outer peripheral busbar of the diamond sintered body chip or in the direction of the inner peripheral busbar of the recess of the metal member for joining the diamond sintered body chips It is possible to obtain an accurate center without misalignment while maintaining the force.

(2) In the deviating operation of the diamond sintered body chip during the manufacturing process, the deviating time can be shortened, so that the manufacturing cost can be reduced.

(3) Since the metal member for joining the diamond sintered body chips is interposed between the shank and the diamond sintered body chips, cracks due to thermal expansion of the diamond sintered body chips do not occur. It is possible to more firmly bond the diamond sintered body chip and the metal member.

(4) When the diamond sintered body chip and the metal member are joined by the active metal brazing material containing titanium,
Since it is not necessary to make the entire shank an inert gas atmosphere or a vacuum state, the device can be downsized.

[Brief description of drawings]

FIG. 1 is a front view of a center showing an embodiment of the present invention.

FIG. 2 is a vertical cross-sectional view of the center shown in FIG.

FIG. 3 is an exploded perspective view of the center shown in FIG.

FIG. 4 is a horizontal sectional view of a PCD chip.

5 is an explanatory diagram showing a manufacturing procedure of the center shown in FIG. 1. FIG.

FIG. 6 is an exploded perspective view of a main part of a center according to another embodiment of the present invention.

[Explanation of symbols]

1 Shank 1a Recess 2 PCD Tip 2a Cylindrical Body 2b Tip 3 Metal Member 5 Active Metal Solder 6 Silver Solder G, G _m Groove W Groove Width d Groove Depth

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Tetsuro Aiura 210 Takeno, Tanamaru-cho, Ukiha-gun, Fukuoka Noritake Diamond Co., Ltd. (72) Inventor, Takashi Arase, 210 Takeno, Oji, Tanushimaru-cho, Ukiha-gun, Fukuoka Noritake Diamond Co., Ltd.

Claims (6)

[Claims] 1. A plurality of grooves for guiding a brazing material are formed in a peripheral busbar direction of the diamond sintered body chip at a center where a diamond sintered body chip is fixed by brazing in a recess formed at the tip of a shank. A center that is characterized by 2. The center according to claim 1, wherein a metal member for joining the diamond sintered body chip is interposed between the shank and the diamond sintered body chip. 3. A diamond sintered body chip joint between the shank and the diamond sintered body chip at a center where a diamond sintered body chip is fixed by brazing to a recess formed at the tip of the shank. A center, characterized in that a plurality of grooves for guiding a brazing material are formed in the inner peripheral generatrix direction of the concave portion of the metal member with the metal member for use interposed. 4. The center according to claim 2, wherein the diamond sintered body chip and the metal member are joined by an active metal solder containing titanium. 5. The metal member is kovar, molybdenum,
It is any of cemented carbides, It is characterized by the above-mentioned 2,
Centers described in 3 and 4. 6. The groove formed in the diamond sintered body chip or the metal member has a width of 0.2 to 1.0 mm and a depth of 0.
At least 4 or more of 1 to 0.5 mm are formed at equal intervals in the generatrix direction, and 1 to 5 characterized by the above-mentioned.
Center listed.