JPH07266106A - Throwaway tip - Google Patents

Abstract

PURPOSE:To decrease the consumption volume of a superhigh pressure sintered body to reduce the manufacturing cost, and enhance the strength of a compound material or the durability of a tip. CONSTITUTION:In a tip in which the undersurface 5a of a cemented carbide 5 of a compound material 6 obtained by burning a CBN sintered body 4 on the rake face 7 side monolithically with a cemented carbide 5 on the opposite side, is brazed on the bottom face of a recessed part 3 of a tip body 2, the relationship between the lengths L1, L2 of cutting edges K1, K2 starting from a corner C of the CBN sintered body 4 in the directions along two sides H1, H2 of the tip body 2 which put the corned C between them, is determined to be L1> L2 to have a convenient side. Since the cutting edges are arranged, to have a convenient side, a small amount of the CBN sintered body 4 is enough to maintain specified lengths of the cutting edges. Because a brazing filler metal enters between the undersurface 5a of thecemented carbide 5 and the bottom face of the recessed part 3 of the tip body 2, any overhang is not produced on the CBN sintered body 4, and thus the strength of the tip against main component force applied to the tip during the cutting operation is large.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a throw-away tip (hereinafter, also simply referred to as a tip), and more specifically, it is suitable for cutting cast iron, high hardness metal material, or non-ferrous metal such as aluminum. CBN (cubic boron nitride) sintered compacts and diamond sintered compacts and other high-pressure sintered compacts are integrally formed with cemented carbide (pedestal) to form a composite, which is the cutting edge. As a chip formed by brazing the cemented carbide to a recess formed in a corner of the chip body.

[0002]

2. Description of the Related Art Conventionally, as a typical example of this type of chip, an ultrahigh pressure sintered body (layer) and a cemented carbide (layer) are vertically formed in a concave portion of a corner of a chip body (base material). It is known that a composite body formed into a layer and having a flat surface and an approximately isosceles triangle (equilateral triangle) is fixed by brazing. by the way,
An ultra-high pressure sintered body such as a CBN sintered body or a diamond sintered body has extremely excellent wear resistance, but is extremely expensive. Therefore, when it is used as a throw-away tip, the amount of the material used is limited. The problem was how to reduce the cost and reduce the manufacturing cost.

Under these circumstances, the technique of Jitsukaihei 3-47707 has been proposed. In this product, a composite of an ultra-high pressure sintered body and a cemented carbide is both formed into a substantially rectangular parallelepiped and formed into a serially elongated body, and the ultra-high pressure sintered body that serves as the cutting edge is located near the corner. In this way, it is brazed and fixed to the concave portion (notch portion) of the corner of the chip body. In other words, this is a chip body in which the composite (ultra-high pressure sintered body) is an isosceles triangle and the lengths of the cutting edges that sandwich the corners are not the same as in the above, but the ultra-high pressure sintered body has an elongated shape. The cutting edge along one side is designed to secure a predetermined cutting edge length, while securing a predetermined cutting edge length while reducing the amount of ultra-high pressure sintered compact, This is a reduction.

[0004]

[Problems to be Solved by the Invention] Japanese Utility Model Laid-Open No. 3-47707
In the technique described in Japanese Patent Publication, although such an effect is obtained, since the fixation of the composite body to the recess of the chip body depends on the brazing, there are the following problems to be solved. That is, in this technique, when the composite is brazed, the ultra-high pressure sintered body is not wetted by the braze, so that the composite is fixed to the recess of the chip body by brazing with the cemented carbide. In other words, brazing is applied to the bonding interface between the cemented carbide and the bottom surface and wall surface of the recess, so brazing is performed, but since the super-high pressure sintered body does not wet the braze, the space between the super-high pressure sintered body and the recess is The brazing material does not enter. Therefore, as shown in FIG. 9, between the bottom surface 72 of the recess of the chip body 71 and the ultra-high pressure sintered body 73, the brazing material 75 that has entered the bonding interface between the cemented carbide 74 and the bottom surface 72 of the recess.
As a result, a minute gap δ corresponding to the thickness is formed, and the ultrahigh pressure sintered body 73 is in a state of overhanging, so to speak. Therefore, when used in turning or the like that receives a large cutting resistance (main component force) P, chipping (blade spill) or cracking of the cutting edge is likely to occur during cutting, and further, the ultra-high pressure sintered body 73
There is also a problem that the interface between the cemented carbide 74 and the cemented carbide 74 is separated.

The present invention has been devised in order to solve the above-mentioned problems, and it is possible to secure a small amount of use of the ultra-high pressure sintered body to reduce the cost and to improve the strength and strength of the composite. Its purpose is to improve the durability of the chip.

[0006]

In order to achieve the above object, the throw-away tip of the present invention is a composite body formed by integrally sintering a super-high pressure sintered body forming a cutting edge with a cemented carbide. Is fixed by brazing the cemented carbide to a recess formed in a corner of the chip body, wherein the cemented carbide is arranged on the side opposite to the rake face and soldered to the recess. The length from the tip of the corner of the cutting edge formed by the ultra-high pressure sintered body in the direction along the two sides of the chip body that sandwiches the corner is one is longer than the other. Characterize. In this case, the length of the long cutting edge from the corner tip is 2
It is preferable that the length of the short cutting edge from the corner tip is 1 mm or more and 3 mm or less, from the standpoint of practicality and cost, or in terms of chip disposability and brazing strength. . And in these, the said composite body sees from a rake surface side, forms the substantially trapezoid which makes the edge | side facing the long-formed cutting edge substantially parallel, or makes the long-formed cutting edge a long side. When formed into a substantially rectangular shape,
Since the blade width of the cutting blade is constant, it is preferable in terms of chip disposability and brazing strength.

[0007]

According to the tip of the present invention, since the brazing material is inserted between the cemented carbide and the concave portion of the tip body which are arranged on the side opposite to the rake face, there is no gap therebetween. That is, the ultra-high pressure sintered body does not have the above-mentioned overhang. Therefore, the main component force at the time of cutting acts on the concave portion of the chip body through the composite (super high pressure sintered body and cemented carbide) and the brazing material layer. That is, by increasing or decreasing the length of the cutting edge, it is possible to improve the strength of the composite or the durability of the chip while securing a small amount of use of the ultra-high pressure sintered body.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment embodying a throw-away tip according to the present invention will be described in detail with reference to FIGS. In the figure, reference numeral 1 denotes a substantially flat triangular plate-shaped tip (triangular tip), and in this example, a recess 3 formed at one corner C of a cemented carbide chip body 2 has a plan view (rake face). A composite 6 having a substantially trapezoidal shape and consisting of two upper and lower layers of a CBN sintered body 4 and a cemented carbide 5 is fixed by brazing. As shown in FIGS. 3 and 4, the recess 3 has a bottom surface 8 that is substantially parallel to the rake face 7, and
And two wall surfaces 9 and 10 that intersect at a substantially right angle, and are formed so as to restrain the composite body 6. The bottom surface 8 has the same planar shape as that of the composite body 6 and has a substantially trapezoidal shape with a predetermined width W, and extends along one side H1 of the two sides sandwiching the corner C of the chip body 2. The length L1 from the tip of the corner C is formed longer than the length L2 along the other side H2, and the side opposite to the side forming the length L1 (along the corner angle intersecting the bottom surface 8 and the wall surface 9). The sides) are parallel to each other, and the side facing the short side L2 having the length L2 intersects L1 at a substantially right angle. The corner C of the bottom surface 8 has a small radius in the range of about 0.2 to 1.6 mm.

The complex 6 has the same plane (upper surface) and lower surface as the shape of the bottom surface 8 of the recess 3, and the cemented carbide (layer) 5 having a constant thickness forming a pedestal and thinner than that. A cemented carbide 5 which is obtained by integrally sintering and forming a CBN sintered body 4 having a predetermined thickness, and is arranged on the side opposite to the rake face 7 side.
It is mounted on the bottom surface 8 of the recess 3 via the lower surface 5a of the same, and while the side surface is restrained by the wall surfaces 9 and 10, it is brazed and fixed to the recess 3 by silver brazing or the like. At this time,
The composite 6 is brazed between the lower surface 5a of the cemented carbide 5 and the bottom surface 8 of the recess 3 and between the side surfaces 5b and 5c of the cemented carbide 5 and the wall surfaces 9 and 10 of the recess 3 (FIG. 5 and FIG. 6). Therefore, at the interface between the side surface of the CBN sintered body 4 and the wall surfaces 9 and 10 of the recessed portion 3, a minute gap substantially corresponding to the thickness of the brazing material layer R is formed. Thus, in this example, C in the direction along the two sides H1 and H2 of the chip body 2 sandwiching the corner C is used.
Corner C at cutting edges K1 and K2 formed by BN sintered body 4
It is a self-supporting insert (right) having a cutting edge length with lengths L1 and L2 from the tip set to L1> L2. In this example, L1 is set to 3 mm and L2 is set to 2 mm. Incidentally, the thickness of the CBN sintered body 4 is 1 mm, and the thickness of the cemented carbide 5 is 1.5 mm.

In the thus-formed tip of this example, a composite body of a conventional isosceles triangle or an equilateral triangle in which both L1 and L2 are 3 mm and the cutting edge lengths of both sides are the same (super The amount thereof can be made smaller than that of the high pressure sintered body), and the direction in which the main component force of the cutting resistance is received, that is, the lower surface 5a of the cemented carbide 5 forming the composite 6 and the concave portion of the chip body 2 Since there is the brazing material layer R between the bottom surface 8 and the bottom surface 8 of the metal 3, even if the main component force P at the time of cutting is received as shown in FIG.
Since there is no overhang due to the gap corresponding to the thickness of the brazing material layer as in the conventional case, the strength of the composite 6 can be kept high. As a result, the cutting edge that has been a problem in the past (super high pressure sintered body)
It is possible to effectively prevent chipping or cracking of the composite, or breakage of the composite such as separation of the CBN sintered body 4 and the cemented carbide 5.

The lengths L1 and L2 of the cutting edges K1 and K2
May be set in consideration of the cutting depth depending on the shape of the work, the size of the chip, and the bonding strength by brazing. However, L1 should be about 3 mm (about 2.5 to 3.5 mm) in normal processing, and if it is about 5 mm, it can be applied to a wide range of processing. For general turning, it may be in the range of 2 to 5 mm. Regarding L2, the smaller the size, the more the amount or cost of the ultra-high pressure sintered body can be reduced. However, from the viewpoint of chip disposability and brazing strength, it is preferably about 1 to 3 mm. The thickness of the ultra-high pressure sintered body forming the composite is preferably about 0.8 to 1.1 mm in terms of strength and economy. In addition, the thickness of the cemented carbide (layer) depends on the thickness (strength) of the chip body, but for the same reason, 1.3-
3.7 mm is preferable.

In the above-described embodiment, the triangular (equal triangle) chip is embodied, but the present invention can be embodied in a cutting chip having an appropriate shape such as a diamond chip.
Note that the planar shape of the composite is, when it is embodied in the case where the angle θ formed by the two cutting edges (ridge lines) K1 and K2 sandwiching the corner C in plan view is not a right angle, like the triangular tip of the above embodiment. Is preferably substantially trapezoidal with the sides facing the long cutting edge K1 having the length L1 being parallel. This is because the blade width W of the cutting edge K1 becomes constant, the chip disposability becomes stable, and the brazing strength is preferable. The same applies to the case of embodying a rhombus chip in which the angle formed by the long and short cutting edges sandwiching the corner is an acute angle.

Further, as shown in FIG. 7, both long and short cutting edges K1 and K that sandwich a corner C like a pentagonal (shaped) tip 21.
Even when the angle θ formed by 2 is obtuse, the planar shape of the composite body 26 may be substantially trapezoidal with the sides facing the long cutting edge K1 forming the length L1 being parallel. This is because the blade width W of the cutting blade K1 becomes constant, which is preferable in terms of chip disposability and brazing strength. However, it goes without saying that in any of the chips, the plane shape of the composite can be embodied without a special trapezoid. Further, as shown in FIG. 8, even when the present invention is embodied in a case where the angle θ formed by the long and short cutting edges K1 and K2 sandwiching the corner C such as a square (or rectangular) chip 31 is right angle, Three
For the same reason, the planar shape of 6 is preferably a substantially rectangular shape (rectangular shape) having the long cutting edge K1 as the long side.

In the above embodiment, the CBN sintered body was used as the super high pressure sintered body forming the composite, but the ultra high pressure sintered body in the present invention is not limited to this, and diamond is used. It may be a sintered body or the like. The tip body may be made of high-speed steel or the like, as long as there is no problem in brazing, in addition to cemented carbide. Further, although the chip body is embodied as a negative chip in the above, it can be embodied as a positive chip. Further, it is not limited to a regular polygon such as a triangle, a square, a pentagon, and a hexagon, a rectangle (parallelogram), or a regular polygon, and can be embodied in any chip. And
As a matter of course, the present invention can be embodied not only in one corner but in all corners.

[0015]

As is apparent from the above description, according to the throw-away tip of the present invention, the length of the cutting edge is shortened to ensure that the amount of the ultra-high pressure sintered body used is reduced. Therefore, since the cost is reduced and the cemented carbide forming the composite is disposed on the side opposite to the rake face and brazed, the ultrahigh pressure sintered body has no overhang. Therefore, the main component force during cutting acts on the concave portion of the chip body through the composite and the brazing material layer, so that the strength or durability of the composite can be improved. That is, the effective cutting edge length can be maintained at a predetermined length at low cost, and chipping or cracking or separation of the interface between the ultrahigh pressure sintered body and the cemented carbide can be effectively prevented. As a result, it is expected that the life of the tool will be extended and the roughness of the finished surface will be improved.

[Brief description of drawings]

FIG. 1 is a perspective view of an embodiment in which a throw-away tip according to the present invention is embodied as a triangular tip.

FIG. 2 is an enlarged view of a main part in FIG.

FIG. 3 is an enlarged perspective view illustrating a recess of the chip body.

FIG. 4 is an enlarged view showing a recess of the chip body as seen from a flank side.

FIG. 5 is an enlarged view of a cutting edge portion (composite body) viewed from the rake face side.

FIG. 6 is a front view seen from the flank side in FIG.

FIG. 7 is an enlarged view of a cutting edge portion (composite body) of an embodiment in which the throw-away tip according to the present invention is embodied as a pentagonal tip as seen from the rake face side.

FIG. 8 is an enlarged view of a cutting edge portion (composite body) of an embodiment in which the throw-away tip according to the present invention is embodied as a square tip as seen from the rake face side.

FIG. 9 is an enlarged view seen from the flank side for explaining the problems of the conventional chip.

[Explanation of symbols]

 1,21,31 Throw-away tip 2 Tip body 3 Recess 4 CBN sintered body (super high pressure sintered body) 5 Cemented carbide 5a Lower surface of cemented carbide 6,26,36 Composite 7 Rake surface 8 Bottom of recess C Corners H1 and H2 Edges of the chip body that sandwich the corners K1 and K2 Cutting edge of CBN sintered body L1 Length from long edge of cutting edge L2 Length from short edge of cutting edge

Claims (5)

[Claims] 1. A composite body obtained by integrally forming a cutting edge ultra-high pressure sintered body with a cemented carbide, and brazing the cemented carbide in a recess formed in a corner of a chip body. A throwaway tip that is fixed by means of the cemented carbide, the cemented carbide being disposed on the side opposite to the rake face and brazed to the recess, and in a direction along two sides of the tip body that sandwiches the corner. 2. A throw-away tip, characterized in that one of the cutting edges of the above-mentioned ultra-high pressure sintered body is formed longer than the other from the corner tip. 2. The throw-away tip according to claim 1, wherein the length of the long cutting edge from the tip of the corner is 2 mm or more and 5 mm or less. 3. The throw-away tip according to claim 1, wherein the length of the short cutting edge from the tip of the corner is 1 mm or more and 3 mm or less. 4. The throw-away method according to claim 1, wherein the composite is formed in a substantially trapezoidal shape in which, when viewed from the rake face side, the long cutting edge is substantially parallel to the opposite side. Chips. 5. The throw-away tip according to claim 1, wherein the composite is formed in a substantially rectangular shape having a long cutting edge as a long side when viewed from the rake face side.