JP2000084707A - Throwaway tip - Google Patents

Abstract

PROBLEM TO BE SOLVED: To divide chips excellently at the time of low depth of cut and a low feed rate, by forming a pair of hollows on a nose part of a throwaway tip, symmetrically relative to a bisector for roughly bisecting the nose part. SOLUTION: Hollows 16 are formed on the further outside of a tip than projections 13. The hollows 16 are a pair of hollows having elliptic shapes, and are positioned symmetrically relative to a straight line for roughly bisecting a nose part 7, and the distance between two major axes of the elliptic shapes increases as they separate from the nose head, and the elliptic arc of an opening part is arranged nearly along the boundary between a land part 9 of the nose part 7 and an inclined part 10. In the region of low depth of cut, chips produced at the nose part 7 are deformed immediately by the hollows 16. The hollows 16 lead the flow of the chips to a lower position of the inclined part 10, and makes it collide surely with the projections 13, to thereby enlarge the deformation. Hereby, the chips are divided excellently.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a throw-away insert which is detachably attached to a tool body of a cutting tool, and more particularly to a chip breaker in a low cutting area.

[0002]

2. Description of the Related Art As a throw-away chip used for chip processing in a low cutting area, a cutting face connected to the nose section is provided in order to improve the processing ability of chips generated at the nose section of the cutting blade during cutting. There is a type provided with a projecting breaker. In the protruding breaker, the protruding portion provided toward the nose portion has a convex curved surface shape higher than the cutting edge, and the radius of curvature of this convex curved surface decreases as approaching the upper end of the protruding portion, and further, the center of curvature is further reduced. , So as to be closer to the upper end of the breaker, the farther from the tip of the nose portion. This indexable tip is configured as described above,
Slow the rise of the protrusion to prevent chip clogging,
In addition, the tip of the projection is brought sufficiently close to the tip of the nose to ensure the ability to separate chips in the low-cut area. Japanese Patent Application Laid-Open Nos. 6-79505 and 6-55312 disclose examples of this type of throw-away chips.

On the other hand, there is an example in which a large rake angle is provided in one or more stages for the same purpose. This is called a second-stage rake, and is provided from the cutting edge to a land portion, a first-stage rake angle, a second-stage rake angle, and the second-stage rake angle is made larger than the first-stage rake angle. There is a feature that chips can be processed without making contact with the second rake face. However, the second-stage rake does not allow the second-stage rake face to approach the cutting edge, and is therefore not applied to the area where it is used, especially for applications such as low cutting.

[0004]

In recent years, with the improvement of forging accuracy, the stock of parts materials has tended to decrease, and the processing of parts has centered on light cutting with low cutting and low feed. Specifically, cutting conditions with a cutting amount of 1 to 2 mm and a feed amount of about 0.2 to 0.3 mm / rev have been conventionally used, but at present, the cutting amount is 0.5 to 1 mm and the feed amount is Cutting of about 0.15 to 0.4 mm / rev is becoming the center. Therefore, the chips include thinner and softer chips than in the past, and the conventional breakers cannot cut the chips into small pieces. Specifically, ductile SCr steel or boron steel that is not easily plastically deformed has been used as a work material instead of the conventional SC steel and SCM steel, but the conventional breaker has a ductile work material. In, it is difficult to divide the chip even if the chip is deformed.
After all it is hard to divide. Further, since the width of the chips is small, the outflow direction is unstable, and there is a case where the chips are not deformed because the chips do not hit a predetermined position of the breaker.

[0005]

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a throw-away insert having a low cutting depth, a good chip cutting ability at a low feed rate, and a chip discharging property.

[0006]

In order to achieve the above object, the present invention has been achieved by using a means for deforming while the chip temperature is still high immediately after chip generation, that is, while the chip is soft. In a throwaway tip having a substantially polygonal shape and provided with a mounting hole penetrating the center of the throwaway tip, the nose portion of the throwaway tip, It is a throwaway tip characterized by providing a pair of depressions so as to be symmetrical with respect to a bisector that divides into approximately two, and furthermore, in order to stabilize the chip outflow direction, A throw-away tip provided with a pair of spherical projections adjacent to each other so as to be symmetric with respect to the bisector of the throw-away tip. Hereinafter, the operation will be described in detail.

[0007]

The function of the depression will be described first along the flow of chips in the low cutting area. First, chips generated in the nose portion are immediately deformed by the depression. As a result, deformation can be applied while the chip temperature is high, so that the energy required for the deformation is small and is effective for all work materials. However, it is particularly effective for work materials that harden after cooling such as boron steel. This depression also guides the chip flow to a lower position on the ramp, ensuring that it hits the projection and makes the deformation larger.

At this time, if a plurality of recesses are provided at intervals, a portion that passes through the recess in the width direction of the chip and a portion that does not pass through the recess are generated, so that the chip is unevenly deformed in the width direction. Then, it becomes easier to divide by deformation at the next spherical projection or the like. Specifically, a depression is provided in the land portion of the nose portion, but is provided near the tip of the nose portion so that the depression is cut off. The interval between the two depressions is 0.1 to 0.3 mm, which is the shortest distance between the two depressions.

[0009] Since this depression is intended to improve the chip controllability at the time of low cutting, it is preferable to provide the depression in a land portion in the nose portion. However, the following disadvantage occurs when the shape is such that it fits in the land portion. That is, since a sufficient length cannot be obtained in the land width direction, the entered chips are not smoothly discharged and the cutting resistance is increased, and a sufficient depth is difficult to obtain in design, resulting in an insufficient action. Further, when the recess is provided deeply, the shape of the edge of the depression becomes sharp and easily chipped, and does not work in the case of cutting or feeding exceeding the land width. Therefore, the inconvenience is solved by extending the depression to the inclined portion.

On the other hand, if the dent extends too far toward the inside of the chip, the portion does not work and the strength is rather reduced. For the reasons described above, the depression starts from the land part and is 0.2 to 0.3 mm inward of the chip.
It is preferable to provide over. Also, from the viewpoint of the edge strength, it is preferable to provide a depression from a position where the land portion remains 0.05 mm or more, preferably 0.1 mm or more.

The depth d of the depression is 0.05 to 0.2 mm from the height of the cutting edge of the nose. If the depth is too shallow, the effect will be insufficient. If the depth is too deep, the strength of the cutting edge will be reduced, and production will be difficult. The shape of the depression is preferably elliptical so as not to be chipped, and the shape of the cross section in the minor axis direction of the ellipse is arc-shaped so that chips flow smoothly.

Chips deformed by the depression hit the projection and bend. Since the chips come into contact with the two protrusions at one place each, a total of two places, the chips can be reliably captured even if the chips are narrow and the outflow direction is unstable.
A pocket is formed between the two contact points of the projection, and the portion between the two contact points of the chip enters into this, so that the chip is also deformed in the width direction and is further divided. It will be easier. Since the surface of the projection is substantially spherical, it has the smallest contact area regardless of the chip width and flowing direction.
Chip flow is smooth and does not increase cutting resistance. Even when the chips get over the projections, the surfaces of the projections are substantially spherical, so that the chips flow smoothly and do not hinder the operation of the projections.

The height h of the projection is preferably the same as or higher than the cutting edge of the nose portion. Specifically, the height h is in the range of 0 to 0.1 mm, preferably about 0.05 mm. If the height of the projections is too low, the chips will get over and cannot be sufficiently deformed, and if too high, the chips will be clogged.

The position of the projection is determined as follows. When a plane parallel to the straight line from the tip of the nose to the tip center and passing through the center of the spherical projection is defined, the distance L1 between the projection surface on the plane and the nose is 0.8 to 0.9 mm. I do. If the thickness is less than 0.8 mm, the chips are likely to be clogged, and if it exceeds 0.9 mm, the curl of the chips becomes too large. The distance between the two protrusions is 0.4 to 0.7 mm as the distance between the centers of the protrusions. If the distance is too short, the contact area of the chips increases, and the effect of providing two projections is lost. If the distance is too long, the chips cannot be caught. If the above conditions are satisfied and the radius of the spherical projection is adjusted in the range of 0.4 to 0.6 mm, good results can be obtained.

When the chip gets over the projection, it collides with the projection, so that the chip can be bent and divided. The protrusion is set 0.05 to 0.2 mm higher than the protrusion. Hereinafter, embodiments of the throw-away tip of the present invention will be described with reference to the drawings.

[0016]

1 is a plan view of this embodiment, and FIG. 2 is a front view thereof. However, in FIG. 2, the projections, protrusions, chip lower surface, and the like are omitted. The tip body 1 of the throw-away tip is formed by forming a hard material such as cermet or cemented carbide into a polygonal shape (a rhombus in the illustrated example), and a pair of upper and lower surfaces 2 arranged in the thickness direction. The lower surface 2 has four side surfaces 3 provided perpendicularly to the lower surface 2 and a mounting hole 4 penetrating the center of the throw-away tip 1. The upper surface 3 includes a boss surface 5 having a planar shape orthogonal to the mounting hole 4 and a rake surface lower than the boss surface 5.
A line of intersection between the upper surface 2 and each of the side surfaces 3 is a cutting edge 6, and a nose portion 7 is formed between the adjacent cutting edges 6. As a result, the side surface 3 is a flank during cutting. As shown in FIG. 2, the cutting edge 6 has a high area near the nose portions 7 at both ends and a low center area, and is generally concave. An inclined cutting blade 8 is provided in a region between the central region where the cutting blade 6 is lowered and the nose part 7. The rake face is provided with a land portion 9 provided flat along the entire edge of the chip along the cutting edge 6, an inclined surface 10 inclined inside the land portion 9 so as to become lower toward the center of the chip, and a chip inner side than the inclined surface. A series of flat bottoms 1
1, a rising surface 12, which is an inclined surface connecting the bottom portion 11 and the boss surface 5;

Hereinafter, the configuration of the breaker will be described.
FIG. 3 shows a cross section taken along the line AA shown in FIG.
4 to 8 show cross-sectional views taken along line -F. From these drawings,
The nose portion 7 is provided with a pair of approximately 1/4 spherical protrusions 13 so as to be symmetric with respect to a straight line bisecting the nose portion, and further provided with a protrusion 14 adjacent to the center of the chip. ing. The top of the projection 13 is set lower than the projection 14 and higher than the cutting edge of the nose. A pair of protrusions 1
A pocket 15 is formed by the space between the three. In this embodiment, the pair of projections 13 partially overlap. Projection 1
4, the width is increased toward the center of the chip. The upper surface of the projection 14 is the boss surface 5. As a result,
A large seating area at the time of attachment to the tool body is ensured. On the other hand, a depression 16 is provided outside the chip with respect to the protrusion 13. In this embodiment, depression 1
Reference numeral 6 denotes a pair of depressions having an elliptical shape, which are located symmetrically with respect to a straight line bisecting the nose portion 7 approximately, and 2
The distance between the long axes of the elliptical books increases as the distance from the tip of the nose increases, and the elliptical arc of the opening is arranged substantially along the boundary between the land 9 and the inclined part 10 of the nose. Most of the depression 16 is provided in the inclined portion 10, but a portion extends to the inside of the land portion 9. Depression 16
Has a maximum depth of about 0.1 mm with reference to the land portion 9, and the inside of the depression 16 has a smooth substantially spherical shape. The bottom portion 11 has a nose portion 7 in FIG.
The groove has a concave shape so that the groove width W2 becomes the largest at a distance L2 from the groove. As a result, the volume of the breaker is ensured even in the case of medium feed or high feed at a high cut, and chip clogging is prevented. The width W3 of the bottom portion 11 is the smallest at a position away from the nose portion 7 by a distance L3. As a result of making the width W2 of this portion the narrowest, the area of the boss surface 5 can be increased to secure a seating area, and such a narrow portion can be used as an index indicating the maximum cut amount by the worker. Can be easily visually recognized.

The low-cut or low-feed cutting area is:
Cut amount 0.3-2.0mm, feed amount 0.3mm
/ Rev or less. In the low cutting region, chips generated in the nose portion are immediately deformed by the depression 16. As a result, deformation can be applied while the chip temperature is high, so that the energy required for the deformation is small and is effective for all work materials. However, it is particularly effective for work materials that harden after cooling such as boron steel. In addition, the depression 16 guides the flow of the chips to a lower position of the inclined portion 10 and reliably causes the chip to collide with the projection 13, thereby increasing the deformation. Further, when a plurality of depressions 16 are provided at intervals as in the present embodiment, the chips are unevenly deformed in the width direction, so that the chips can be more easily divided by the deformation at the next breaker.

Next, the chips hit the projections 13 and bend.
At this time, the chips consisted of two protrusions 13 and one place each, a total of 2
Since the contact is made at two places, it is possible to surely catch the chips having a narrow width and an unstable outflow direction. In addition, a pocket 15 is formed between the two contact points, and the central portion of the chip enters the inside thereof. Therefore, the chip is also deformed in the width direction, so that the chip is more easily divided. Since the surface of the projection 13 has a substantially spherical shape, the minimum contact area is obtained regardless of the width and the flowing direction of the chip, so that the flow of the chip is smooth and the cutting resistance is not increased. The projection 16 is the cutting blade 6
In most cases, the chips are bent and divided by the projections 13.
Even if it gets over, it collides with the protrusion 14, so it bends,
Can be divided. At this time, since the surface of the projection 13 is substantially spherical, chips flow smoothly and do not hinder the operation of the projection 14.

As shown in FIG. 2, since the cutting blade 8 provided continuously with the nose portion 7 is inclined, chips bent in the width direction are generated. Therefore, as compared with a flat chip generated when the cutting edge is not inclined, even the same cut is more likely to be divided, and even at a low feed and a low cut, an obstacle due to the continuous chip hardly occurs. This is particularly effective during round-up processing in which the contact length between the cutting blade and the work material is long.

Cutting edge 6 and boss surface 5 of indexable insert
Is larger as the distance from the nose portion 7 becomes closer to the center of the cutting edge. Regarding the breaker width,
The width W2 at a position closer to the center is smaller than the width W1 at a position closer to. Therefore, at a position away from the nose portion 7, the chips bend with a smaller radius of curvature, so that, for example, in the case of a high cutting area reaching about 2/5 of the entire cutting edge length and at a low feed rate, the chips are removed. Active breakage of the breaker wall can be easily achieved by making it bend slightly.

On the other hand, when the feed amount is, for example, 0.5 mm
In the high feed area larger than / rev, the nose portion 7
1 Since the width of the groove is as large as W1 at the distant position, clogging hardly occurs even when a large amount of chips is generated. Furthermore, since the land 9 at the center of the cutting blade 6 used at the time of high cutting is wide, the cutting blade is strengthened and used for high-feed machining such as chamfering to achieve good working efficiency. Obtainable. Further, in the indexable insert of the embodiment, since both the upper surface and the lower surface are symmetrical with respect to a point or a line, when this is seated on the tool body, the protrusion or the narrow portion of the breaker width is formed on the tool body. Because they are in contact on average and over a large area,
Good seating stability can be obtained.

The planar shape of the chip body is not limited to the rhombus of the above embodiment, but may be another quadrangle such as a parallelogram or a polygon such as a triangle. The shape of the breaker may be different from the embodiment as long as the dimensions directly related to the effects of the present invention, such as the width and the depth, match. Although the upper and lower surfaces of the throw-away tip of the embodiment have the same shape, they may have different shapes.
Further, it is needless to say that the shapes of the upper surface and the lower surface are not limited to symmetric shapes.

[0024]

According to the present invention, when the cutting depth is low, the chip is deformed immediately after the chip is generated due to the depression, so that the resistance is small.
In addition, since the chips are guided to a lower position of the breaker groove, the effect of the next breaker is significantly improved. The projections can reliably capture, deform, and divide chips whose flow at the time of low cutting is unstable. In particular, even in the case of a soft chip, the chip is deformed in the width direction by the two-point contact with the chip and the pocket, so that the chip is easily divided. In addition, a large deformation can be obtained by using together with the depression. In addition, since the cutting edge near the nose portion is provided with an inclined portion that is inclined as being away from the nose portion, chips bent in accordance with the inclination are generated, so that the apparent thickness of the chips increases. Therefore, it is easily broken, so that it is easily divided. Further, as the notch increases, the width of the breaker increases in a region away from the nose portion to be used, and the volume of the breaker increases in accordance with an increase in the amount of chips, so that clogging of chips hardly occurs. Furthermore, as the difference in height between the inner wall of the breaker and the cutting edge increases as it approaches the area away from the nose, in other words, the area used for high cutting, the chip is bent with a smaller radius of curvature, Even if the cuts are small, the chips are positively bent, so that good chip discharge performance is ensured. Also, in the case of a high cut, the chip can be easily divided at a position away from the nose portion 7 because the chip is bent with a smaller radius of curvature. Further, even when a large amount of chips are generated in the high feed area, clogging is unlikely to occur. Furthermore, since the cutting blade used at the time of high cutting is strengthened, good working efficiency can be obtained by utilizing it for high-feed machining such as chamfering.

[Brief description of the drawings]

FIG. 1 is a plan view of an example of the present invention.

FIG. 2 is a front view of FIG.

FIG. 3 is a sectional view taken along line AA of FIG.

FIG. 4 is a sectional view taken along line BB of FIG. 1;

FIG. 5 is a sectional view taken along line CC of FIG. 1;

FIG. 6 is a sectional view taken along line DD of FIG. 1;

FIG. 7 is a sectional view taken along the line EE in FIG. 1;

FIG. 8 is a sectional view taken along line FF of FIG. 1;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Chip main body 2 Top surface 3 Side surface 4 Mounting hole 5 Boss surface 6 Cutting edge 7 Nose portion 8 Inclined cutting edge 9 Land portion 10 Inclined surface 11 Bottom portion 12 Rising surface 13 Projection 14 Projection 15 Pocket 16 Depression h Height of projection d Depth of depression

Claims (5)

[Claims] 1. A throw-away tip comprising a substantially polygonal shape and provided with a mounting hole passing through the center of the throw-away tip, which is used by being removably attached to a tool body of a cutting tool. A throw-away tip, wherein a pair of recesses are provided in a nose portion of the nose portion with respect to a bisector bisecting this approximately. 2. The throw-away tip according to claim 1, wherein the recess has at least a shape of an elongated ellipse and / or an arc extending in a cutting direction. 3. The indexable insert according to claim 1, wherein at least a part of the dent is provided so as to cover the land of the nose part, and the dent is cut off near the tip of the nose part. A featured throwaway tip. 4. The indexable insert according to claim 1, wherein the depth of the recess is 0.05 to 0.2 mm from the height of the nose cutting edge. 5. The throwaway tip according to claim 1, wherein a pair of spherical projections is provided adjacent to the bisector of the throwaway tip next to the depression. Chips.