JPH01264702A - Cutting tool - Google Patents

Abstract

PURPOSE:To produce excellent surface finish of the internal and external peripheries and the end faces of a work and cut even every corner with high accuracy by forming outer peripheral three cutting edges of a nearly triangular flat tip into a shape of circular arc with each outside extended outward, and setting each tool angle at 90 degrees. CONSTITUTION:A P point which is shifted from a vertex A of an equal-lateral triangle having vertexes A, B, C to a center of the triangle by a distance l along a center line (a), is set as a tip point of a nose corner, each side of circular arcs is set so that a tool angle epsilon of each cutting edge becomes 90 degrees. A tangential line i at P point of a side cutting edge or cutting edge side 5 is set at right angles to a tangential line j at P point of an end cutting edge or cutting edge side 4, and a center C1 of radius of curvature of the end cutting edge is set on the prolongation of the tangential line i, while a center C2 of radius of curvature of the side cutting edge 5 is set on the prolongation of the tangential line j. When a nose- radius is provided at a tip 6, a center of radius of curvature R is shifted by a correction value equal to the nose radius. When a cutting operation is performed, the tool angle epsilonis set so that a median line passing through a vertex 3A divides the tool angle into equal parts and cutting edge angle becomes 90 degrees. The tangential line j of the end cutting edge 4 is positioned parallel to an axis of a work, the tangential line i of the side cutting edge being perpendicular to the axis of the work.

Description

[Detailed Description of the Invention] [Object of the Invention] (Field of Industrial Application) The present invention relates to cutting tools, and in particular! 1' - The shape is approximately an equilateral triangle, and each cutting edge is an arc shape that bulges outward. The present invention relates to a highly versatile cutting tool that not only provides a finished surface but also allows machining of the corners of objects.

(Prior Art) Generally, a cutting tool is used when cutting the outer circumference of a cylindrical workpiece using a lathe. Among these bits, a throw-away bit is known as one in which a disposable carbide tip is firmly tightened to a bit shank. Various types of tips are available, and triangular tips are usually used when cutting the entire outer periphery (for example, Japanese Patent Laid-Open No. 102412/1983).

(Problems to be Solved by the Invention) However, in the conventional triangular chip described above, the feeding melon must be set small according to the nose radius of the chip, resulting in a decrease in processing efficiency. Machining of right-angled corners of the workpiece was also restricted.

In addition, chips having cutting edges with an arcuate outer periphery cannot be used for machining corners because of the arc shape, and their use has been limited to machining curved surfaces.

Therefore, an object of the present invention is to make the chip according to the above-mentioned prior art H
To provide a highly versatile chip which is devised so that not only the inner periphery and outer periphery but also the end face of a cylindrical workpiece can be processed into a good finished surface using a large feeding melon.

[Structure of the invention]

(Means for Solving the Problems) In order to solve the above problems, the cutting tip and cutting tool according to the present invention have the following conditions.

a) The cutting tip has an almost triangular shape on the P1 side (-
1' cutting tip, and the three cutting edges on the outer periphery should be in the shape of an arc that bulges outward.

b) The front cutting edge should have an arc-shaped curve that is almost parallel to the cutting surface.

C) The transverse cutting edge must be an arcuate curve extending almost perpendicular to the front cutting edge.

d) t, 7J sharpening tool uses the above-mentioned tip with a cutting edge angle of 90 degrees,
It must be attached to the blade holder so that the cutting angle is 90 degrees.

(Function) According to the cutting tip of the present invention having the above-mentioned structural features, it is possible to obtain a good finished surface roughness on both the inner and outer periphery and the end surface under a large feeding melon, and it is possible to obtain good surface roughness even at the corners. It can be processed well. In addition, it can be applied as is to the same applications as conventional substantially triangular tips that replace the arcuate cutting edges.

(Embodiments) Hereinafter, embodiments of the cutting tool according to the present invention will be described with reference to the drawings.

1 to 5 illustrate an indexable tip according to one embodiment of the present invention.

The cutting tip 1 in this embodiment is made of cermet, and as shown in FIG. 1, the planar shape is approximately an equilateral triangle surrounded by three arcuate sides, and has an upper surface 1a and a lower surface 1b. The cutting tip has a biased cutting tip having distances of -like I' and 'sat, and the side surface thereof is provided with an inclination with a clearance angle γ. This chip has a mounting hole 2 H in the center for mounting on the shank, and three nose corners 3A, 3B, and 3C are nailed rotationally symmetrically with respect to the center O of this mounting hole 2. Taking the nose corner 3A as an example to explain the structure of the cutting edge in detail, each cutting edge 3 has each arcuate side set so that the edge angle is ε or 90', and the angular relationship of the cutting edge is has a tangent j to the front cutting edge 4 and a transverse cutting edge 5 having a tangent i substantially perpendicular to the tangent j to the front cutting edge 4.

That is, the tip of this example has a substantially triangular shape surrounded by three arcuate sides, and the cutting edge angle ε at each vertex of the nose corner is as close to 90 m as possible, and is substantially 90° at each vertex. The major feature is that it is structured in a certain way.

Further, to describe the planar shape of the cutting tip 1 in geometrical detail with reference to FIG. A point P located along the center by a certain distance Ml is defined as the tip of the nose corner.

At this time, the tangent i at the tip P point of the cutting edge side 5, which is the transverse cutting edge, is perpendicular to the tangent j at the tip P point of the cutting edge side 4, which is the front cutting edge. In other words, the center C1 of the radius of curvature R of the arc-shaped cutting knife that will become the front cutting edge 4 is set on the extension of the tangent i to the tip of the cutting edge J5. Similarly, the center C2 of the arc-shaped cutting edge that will become the transverse cutting edge 5 is set on the extension of the tangent j at the tip of the front cutting edge 4. With this configuration, the tangents mi and j of the front cutting edge and the lateral cutting edge will be perpendicular to each other at each vertex.

Further, although the cutting edge 6 is generally provided with a conventional nose radius r, it may be 1-mQ. In the case where the nose radius r is provided, the center C of the radius of curvature R is not shifted toward the inside of the chip by the correction amount ε corresponding to the nose radius, thereby resulting in a chip that can perform accurate right-angle corner machining.

The state in which the above-mentioned cutting tip 1 is mounted on the shank 12 will be explained with reference to FIGS. 6 to 8.

The triangular tip 1 is clamped to the tip of the shank 12 by a known and conventional means. That is, the (2) screw 14 is passed through the mounting hole 2 of the chip 1, and the chip of the shank 12 is mounted by screwing into a screw hole (not shown) provided in the center of the seat 15. When actually cutting, in Fig. 6, the cutting edge angle of the tip and the median line a of the apex 3A are 2'! j, and the cutting angle 1 is set to be approximately 90''. At this position, the tangent j of the front cutting edge 4 is approximately parallel to the axis of the workpiece, and the tangent i of the cutting edge is approximately perpendicular. positioned.

Note that S indicates the direction of feed, and in addition to feed Sl in a direction parallel to the axis of the workpiece, feed S2 in a direction perpendicular to the axis can also be taken.

In FIGS. 7 and 8, the front and side surfaces of the shank 12 are ground down in a straight or curved manner to match the front relief 9 and the relief surface 10 of the insert 1, and only the front cutting edge 4 and the lateral cutting edge are covered. The corner part 6 is designed to come into contact with the cutting material.
The tip of is located at the center of the workpiece. Further, the shank 12 is formed with a front clearance angle γ and a lateral clearance angle γ2.

Next, the operation of the tip and cutting tool of the present invention configured as described above will be explained.

FIG. 9 is a partial front view showing a state of cutting by a cutting tool comprising a cutting tool holder 12 having a tip 1 of the present invention removably attached to its tip. Move the tool in the direction S1 parallel to X-X
The cylindrical workpiece 17 can be machined at right angles without any problem even at the stepped portion '18 on the outer periphery. Basically, the mounting angle of the cutting tip 1 on the shank 12 is set so that the cutting edge angle of the tip is approximately 90 degrees, the front cutting edge angle 4 is 0 degrees, and the side cutting edge angle k is 90 degrees. This is because

In addition, in the same figure, the gap between the workpiece and the cutting edge, that is, the clearance angle δ, gradually increases in a curved manner as the distance from the cutting point increases, and this creates a space for the chips to flow out. Ejection performance is improved, and the contact area between the cutting edge and the workpiece is reduced, cutting resistance is suppressed, and chatter vibration can be prevented. Furthermore, compared to a cutting tool that uses a tip with a small nose radius, the radius of curvature of the front cutting edge 4, which is involved in producing a finished surface, is larger, so it is possible to obtain a good finished surface roughness even at a high feed rate.

FIG. 10 is a partial view showing the state in which the end face 19 of the cylindrical workpiece 17 is being machined. What is the case in Figure 9?9
Sending the shank 12 in the radial direction S2 different by 0 degrees, 31
- Finishing the flat surface.

In this case as well, since the shape is line symmetrical with respect to the 45° center line a of the tip 1, corner cutting at a 90° different part can be performed with high efficiency even when the cutter holder is installed as shown in Fig. 9. It shows that it can be done.

Compared to the case shown in Fig. 9, it can be considered that the positional relationship between the front cutting edge and the lateral cutting edge relative to the workpiece has been switched symmetrically with respect to the center line a, and the clearance angle δ increases as the distance from the cutting point increases. The operation and effect are the same as in the case of FIG. In both figures, a small nose radius r is provided at each vertex 6 of the nose corner of the chip 1.

As explained above, one embodiment of the present invention has many effects as described above.

(a) Since the finished surface is created with a cutting edge with a larger radius of curvature than before, the roughness is good even with a large feed rate.

(b) The cutting edge angle at the tip of the nose corner of the cutting edge, which is the cutting point, is 90 degrees, and the absolute values of the front cutting edge angle and the lateral cutting edge angle are made equal to each other in a symmetrical shape from the apex to the center line. Not only the inner diameter and outer diameter, but also the end face in 90' different directions can be machined at 11 times perpendicular corner cutting, which not only improves the processing efficiency but also has excellent versatility. Also, it is possible to feed in both left and right directions with the same tip.

(c) Even though the cutting edge angle is 90 degrees, the front cutting edge and the side cutting edge gradually move away from the machined surface of the workpiece in a curved manner as they move away from the cutting edge, so the conventional cutting edge angle is 90 degrees.
Compared to the 1-tool with a 0 degree straight cutting edge, the contact area between the cutting edge and the machined surface is smaller, so the cutting resistance is smaller and chatter vibrations are less likely to occur. There is also less frictional heat due to contact. As a result, excellent surface finish, dimensional accuracy, and surface quality can be obtained.

(d) Chips generated at the cutting edge are discharged from the gap between the cutting edge and the machined surface, and no chip clogging occurs.

When using a cutting fluid, the presence of the above-mentioned gap allows the fluid to reach close to the cutting point, which has a significant cooling and lubrication effect, extending tool life, reducing cutting resistance, and improving cutting (
It is also useful for cutting wood.

(e) Since the cutting edge is surrounded by a curved line up to the cutting edge,
High cutting edge strength.

(r) From the geometric relationship, the value of the radius of curvature R of the cutting edge can be easily determined from the known values of the diameter of the inscribed circle of the insert and the length g of the cutting edge, in addition to the graphical method. The reverse is also true. Therefore, it is easy to design and manufacture.

Next, other embodiments of the present invention will be described with reference to FIGS. 11 to 28.

In the above embodiment, a relief angle is provided on the side surface of the cutting tip 1 itself, but the present invention is not limited to this, and the relief angle γ of the tip itself may be set to zero so that both sides of the tip can be used. . However, in this example, as shown in FIGS. 11 to 13, the clearance angle γ1 with respect to the tip mounting seat of the blade holder 12. It is necessary to assign γ2 to each. Furthermore, depending on the value of γ, the value of the optical power of the attached chip changes, albeit slightly. This is the case when the rake angle is negative, but the same result occurs even when the rake angle is a negative value other than OQ. This is an angular error.

The examples shown in FIGS. 14 to 18 are examples in which the rake face 7 of the insert 1 is dug to provide a front rake angle β and an upper rake angle α to the front cutting edge and the lateral cutting edge, respectively. In the insert shown in the figure, each cutting edge 6 is further rounded with a nose radius of 1 hair diameter. In this case, the center C1 of the radius of curvature R of the front cutting edge 4 is the radius of the nose It is set on an imaginary line i' that enters the inside of the chip by a distance e corresponding to r.The center c2 of the radius of curvature R of the lock cutting edge 5 and the remaining 1
The center c3 (not shown) of the radius of curvature R of the side is determined in a similar manner. If we take the center C of the arc in this way,
Because the nose radius with a small radius of curvature and the circular cutting edge with a large radius of curvature smoothly continue, the cutting edge J becomes a smooth curve.In addition, the nose end J of the front cutting edge 4 enters the workpiece deepest during cutting. , corners can be processed accurately, and the finished surface is also excellent.

In this example, the tip roller body is a negative tip with no relief angle, so if you use it by attaching it to a holder for negative inserts, or if you give it appropriate rake angles α and β, the actual cutting will be accurate when it is attached to the holder. This can be done with a rake angle of . A knife holder 12 using a negative tip as shown in FIG. 11 usually has clearance angles γl and γ2 of about 5 degrees to 6 degrees.
In this case, the values of α and β of the chip are approximately 10 to 15 degrees. Normally, setting both to the same value facilitates manufacturing, and it also varies depending on the direction of feed. It is advantageous because it can be used as a left- or right-handed tip.

In addition, in FIG. 14, if the rake 7 is configured to form an isosceles triangle between its rear edge or the front cutting edge 4 and the transverse cutting edge 5, it can be machined in one grinding process, and it can be machined in both left and right hands. This is convenient because it can be used as a chip for general use. Also, if the height of the corner part 6 of the cutting edge where the front cutting edge and the lateral cutting edge intersect is made to match the top surface of the chip, the corner part 6 will be located at the same height as the axis of the workpiece, so the corner including processing,
High-precision machining results in r+J performance.

FIG. 19 is a partial plan view showing the state in which the tip 1 shown in FIGS. 14 to 18 is attached to the blade holder 12. FIG. The tip 1 is mounted by a known and conventional means, that is, a bolt 20.
The bolt 14 is fastened to the blade holder 12 by the pin 14, which is rotated by the pin 14. As in each of the above embodiments, the midline a of the cutting edge 6 of the substantially triangular insert is configured to bisect the cutting edge angle ε so that the cutting angle ε is approximately 90 degrees. It is. In Fig. 21, the upper rake angle α is α + γ
11 In FIG. 20, the lateral rake angle β' is β+72. γ1. The value of γ2 is usually about γl-72--6°, and α is determined by taking these angles into account.

It is necessary to determine β.

Now, in the plan view of the vicinity of the tool tip shown in FIG. 22(A), it is assumed that both the cutting angle and the cutting edge angle ε are 90 degrees. At this time, if the rake angle is φ in the front view shown in FIG. ) is 161 degrees. From the geometrical relationship, jan(ε/2) = tan(a″/2)e
osφ, i.e. -1E t ' -2tan 1Lan (-) ・eos
φ) (degrees). Here, at -90°, the angle obtained is ε''-2tan-1 (eosφ) (degrees). If the corrected cutting edge angle ε'' is determined, higher viscosity right angle corner machining will be possible.

The examples shown in FIGS. 23 to 27 are examples in which a radius 40 of radius r' is provided in the thickness direction of each corner of the chip, and the cutting edge strength can be further improved by configuring the rake face in a convex curved shape. At the same time, chatter vibration can be suppressed.

In addition, in the above-mentioned embodiment, an example was explained in which a mounting hole was opened in the center of the chip, but such a mounting hole may not be provided.

Further, as the material of the tip, high speed steel, carbide, coating, cermet, ceramics, diamond, etc. are appropriately selected. Furthermore, the cutting tool using the tip of the present invention is not limited to turning tools, but can also be applied to milling tools, chairs, and polling tools.

FIG. 28 is a partial sectional view of an example in which the present invention is applied to a milling tool, and it is possible to cut the surface of a workpiece at a right angle.

It can also be applied to cutting tools that have conventionally used tips with arcuate cutting edges to obtain excellent surface roughness with large feeds.

〔Effect of the invention〕

As explained above, according to the present invention, although it is a substantially triangular chip with an arc-shaped circumference, the cutting edge angle at the apex of each nose corner is set to 90°, so that not only the inner and outer circumferences of the workpiece but also the end face have right-angled corners. In addition, since the workpiece and the cutting edge gradually separate from the tip of the cutting edge toward the end, there is less cutting resistance, allowing for better cutting, and the cutting edge has a much larger radius of curvature than before. Because of this, good surface roughness can be achieved even at high feed rates.

[Brief explanation of the drawing]

Fig. 1 is a ten-sided view showing a cutting tip according to an embodiment of the present invention, Fig. 2 is a front view of the same, Fig. 3 is a back view of the same, Fig. 4 is a right side view of the same, and Fig. 5 is a left view of the same. 6 is a front view showing the state in which the cutting tip according to the present invention is attached to the shank, FIG. 7 is the same view, FIG. 8 is the left side view, and FIGS. FIG. 11 is a plan view showing the state in which the cutting tool according to the invention is used to process the stepped part of a workpiece, FIG. 11 is a front view showing the state in which the cutting tip according to the invention is attached to the shank, and FIG. The same plan view, FIG. 13 is the same left side view,
Fig. 14 is a plan view showing a cutting tip according to an embodiment of the present invention, Fig. 15 is a front view thereof, Fig. 16 is a rear view thereof, Fig. 17 is a right side view thereof, and Fig. 18 is a left side view thereof. Fig. 19 is a JT view showing the cutting tip according to the present invention attached to the shank, Fig. 20 is a plan view of the same, Fig. 21 is a left side view of the same, Fig. 22 (A) and (B) are An explanatory diagram showing the correction of the cutting edge angle, FIG. 23 is a plan view of a cutting tip according to another embodiment of the present invention, FIG. 24 is a 1E view of the same, FIG. 25 is a front and back view, and FIG. 26 is a right side view of the same. Front view, Figure 27 is the same left side view, Figure 2
FIG. 8 is a partial sectional view of a milling cutter using the tip of the present invention. 1... Chip, 3... Cutting edge, 4... Front cutting edge,
5... Horizontal cutting edge, 6... Corner part, 7... Scooping, 8... Trailing edge, 9... Front escape, 10... Side escape, 12... Nyatsu, 40 ...Roundness. Applicant's agent Yu Sato No. 6 Fig. 6 Fig. 11, S13 Fig. 19 Fig. Jib 2'1 Fig. 22 Fig. 828 Illustrated Procedures Toichi Official Book (Method) August 24, 1988 1 , Indication of the case 1988 Patent application No. 92943 2 Name of the invention Cutting tool 3 Person making the amendment Relationship to the case Patent applicant (307) Toshiba Corporation 4, Agent (Postal code 100) 1988 July 6, 1988 (Shipping date: July 26, 1986) 6. Amended drawings for Australia (Figure 22) Figure 22

Claims (1)

[Claims] 1. A flat cutting tip having a substantially triangular planar shape, in which each of the three cutting edge sides defining at least one side of the top surface of the chip or the bottom surface of the chip has a curvature. It is composed of a part of a circular arc that bulges outward with radius (R), and the apex angle of the nose corner sandwiched between adjacent cutting edges forms a nearly right angle cutting edge angle, and the further away from the apex of this nose corner, the more A cutting tool characterized by being configured such that the pinching angle of the cutting edge is small. 2. The cutting tip has a radius (r) at the nose corner.
Claim: 1. The nose corner has a curved part, and the two tangents at the points of contact between the two arcuate cutting edge sides of the outer periphery continuous with the nose corner and the curve of the nose corner are orthogonal to each other. 1. The cutting tip according to 1. 3. The height of each apex of the nose corner of the cutting tip is the same as the top surface of the tip, and the height of each apex of the nose corner of the cutting tip is the same as the top surface of the tip. The cutting tip according to claim 1 or 2, characterized in that the cutting edge is provided with equal rake angles (α, β). 4. The cutting tool according to claim 3, wherein the rake angle of the chip is corrected so that the blade angle is approximately 90° when the chip is attached to the blade holder. 5. The cutting tip according to any one of claims 1 to 3, wherein the rake face of the cutting tip is constituted by a convex curved surface bulging upward. 6. The cutting tip according to claim 1 or 2, wherein the cutting tip is configured to gradually become thinner in a linear or curved manner as it approaches the apex. 7. Claims 1 to 5, characterized in that a notch is provided in a part other than the center of the arc-shaped cutting edge around the cutting tip.
A cutting tip as described in any of the above. 8. The cutting tip according to claim 1 is removably attached to the tip of a blade holder, the two orthogonal cutting edge sides of the cutting tip are used as a front cutting edge and a lateral cutting edge, respectively, and the cutting angle is approximately 90 degrees. A cutting tool characterized by being set to. 9. The cutting tip according to claim 1 is removably attached to a cutter body or cartridge, two orthogonal cutting edge sides of the cutting tip are used as a peripheral cutting edge and a front cutting edge, respectively, and the cutting angle is approximately 90 degrees. A cutting tool for milling, characterized by being set to.