JPS62271606A - High hardness sintered material cutting tool - Google Patents

Abstract

PURPOSE:To extend a tool life, by providing a groove of specific shape in a face of sintered material in the edge point of a throw away tip and using the groove with its one part functioning as a positive face while the rest part functioning as a chip breaker. CONSTITUTION:Cemented carbide 4', connected with a sintered material 1', is fixed to a bed metal 2' by brazing 7'. The sintered material 1' forms a groove 3' equipped with a face and a chip breaker wall surface. The groove 3', which is constituted of a groove face part 5' and a groove chip breaker part 6', sets, for instance, an angle gamma, formed by the face 5' and the part 6', to 90 deg.-150 deg., edge angle beta to 85 deg. and a rake angle delta to 5 deg.. By the above described setting, damage in the wall surface of the chip breaker part 6' decreases, and a smooth flow of cutting chips can be obtained.

Description

Detailed Description of the Invention 3. Detailed Description of the Invention (Field of Industrial Application) The present invention aims to improve the cutting efficiency of a cutting tool whose cutting edge is equipped with a sintered body containing Danyamond and/or high-density phase boron nitride. A negative-shaped throw-away that is easy to improve and manufacture, increasing the tool life, making it easier to dispose of chips from the workpiece, and maintaining the surface roughness of the workpiece for a long time. The present invention relates to a tool that can obtain cutting performance equivalent to that of a positive-shaped tool, which is difficult to manufacture, by simply modifying the tip.

(Prior Art) In recent years, the usage of cutting tools whose cutting edges are equipped with sintered bodies containing Danyamond and/or high-density phase boron nitride has been rapidly increasing. Cutting tools with Danyamond on the cutting edge are mainly used for cutting nonferrous metals, and cutting tools with a sintered body containing high-density boron nitride on the cutting edge are used for cutting steel materials. It has extremely high hardness compared to conventional cutting tools, making it difficult to process, and it is technically extremely difficult to create a shape with a chip breaker on the rake face during sintering. A sintered body (hereinafter referred to as sintered body) tool containing diamond diamond and/or high-density phase boron nitride with a chip breaker provided on the rake face has rarely been produced. For this reason, chips from the rigid workpiece generally extend for a long time, often causing problems such as getting tangled with the tool or the workpiece, or damaging the surface of the workpiece.

Furthermore, the extremely high hardness of the sintered body allows cutting at high cutting speeds, that is, high efficiency, and the wear resistance of the tool edge is high, making it possible to achieve a long tool life. To achieve this, it is necessary to set a cutting edge shape that matches the cutting conditions such as the material type and hardness of the workpiece, depth of cut, feed, and circumferential speed. However, in reality, almost every cutting process has different conditions depending on the situation, and it is difficult to predict the blade shape that is suitable for the conditions, so it is difficult to set the blade edge shape that matches the cutting conditions in advance and carry out the process. difficult.

Also, when using sintered tools instead of conventional tools,
In many cases, it is desired to use the tool shape as is, and it is rare to use a sintered tool with the optimal cutting edge shape.In particular, there are many cases where it is necessary to make a conventional negative shape into a positive shape. .

In order to solve such a situation, an invention as described in Japanese Patent Publication No. 60-33604, for example, is known to improve the above-mentioned problems. This conventional invention is a sintered body mainly made of Danyamond or cubic boron nitride, which is hot-pressed under ultra-high pressure and high temperature, on at least one corner of a polygonal base metal made of cemented carbide or steel. An indexable insert having a cutting edge made of a hard sintered body mainly composed of carbides, nitrides, or mutual solid solutions or mixtures of metals of group 4a of the periodic table, the surface of the hard sintered body being indexable. A chip breaker for facilitating chip disposal between a part of the alloy that is in a plane parallel to or at a certain angle with the bottom surface of the chip, and further intersects with the surface at a certain angle, forming a plane or curved surface. This is a composite throw-away tip that is characterized by forming a recess that plays the role of. With this conventional invention, for example, it is possible to provide a positive-shaped cutting edge even though it is a negative-shaped tip, and furthermore, by forming a breaker in a part of the alloy, it is possible to create an indexable tip with a breaker. However, it has some drawbacks as described below.

(Problems to be Solved by the Invention) First, in order to form a chip breaker with the sintered body of the cutting edge and a part of the alloy, if the rake face is parallel to the bottom face, it is necessary to A step is provided between the top surface and the rake surface of the sintered compact, and the wall surface connecting the rake surface of the sintered compact and the top surface of the alloy is used as a chip breaker, and the sintered compact is bonded by brazing, etc. The recessed portion of the alloy must be made thinner than when no chip breaker is provided, and naturally the strength of the base metal is lower than when no chip breaker is provided. Furthermore, even when the bottom surface of the alloy and the rake face of the sintered body are given a certain angle to give the cutting edge a rake angle, the part where the sintered body of the alloy is bonded and the part where the chip breaker is formed are at a certain angle. , and the thickness of the alloy becomes thinner at the intersection, so the strength of the indexable insert becomes very low due to the combination of stress concentration and thinner thickness. This is not desirable in practice as it tends to break or break, reducing the rigidity of the tool and causing chatter.Furthermore, the distance between the cutting edge and the chip breaker is limited by the dimensions of the sintered body and can be set at any position. It is inconvenient that it cannot be done. Generally, in the case of indexable inserts in which a sintered body is brazed to the cutting edge, the depth of cut is 0. Therefore, the position of the chip breaker is often required to be at most 1 to 3 points from the cutting edge.On the other hand, the chip breaker can be placed at a distance of 1 to 3 points from the cutting edge. -, the planar dimensions of the sintered body are often about 3 to 5 squares, and therefore the position of the chip breaker is automatically determined to be 3 to 5 squares from the cutting edge. Only some of the locations can be accommodated. In addition, the conventional type has the disadvantage that the shape of the part where the sintered body of the base metal is attached has to be different from that of a general chip breaker, which requires a lot of man-hours and time. This is mentioned as one of the things.

Also, of course, the hardness of the base metal, such as cemented carbide or steel, is lower than that of the sintered body, so if the cutting conditions of the sintered body are severe, it will wear out early and the expected effect as a chip breaker cannot be maintained. It is also possible that it becomes a shape. In addition, as a matter of course, the conventional technique cannot be applied to an indexable chip whose entire upper surface is a sintered body.

The purpose of the present invention is to solve the problem of the above-mentioned conventional technology, which is that the strength of the alloy of the indexable tip is reduced;
The position of the chip breaker cannot be chosen arbitrarily, the shape of the alloy must be different from that without the chimp breaker, and the alloy has a lower hardness than the sintered body, so it wears out quickly and the chip breaker This is an attempt to improve by eliminating or reducing disadvantages such as the possibility of not being able to maintain the shape of the indexable insert, and the inability to use indexable inserts whose entire upper surface is made of sintered material. . Furthermore, in the case of sintered tools, positive-shaped tips require the relief angle to be set by grinding, which requires more man-hours to manufacture than negative-shaped tools, and is economically disadvantageous, such as causing greater wear and tear on the Dunyamond grindstone. This is an attempt to improve this point.

(Means for Solving the Problems) The present invention has been obtained as a result of repeated theoretical and practical research to solve the problems of the above-mentioned conventional techniques. This solves the problem all at once.

The present invention provides a high-hardness sintered cutting tool having a cutting edge of a sintered body containing Danyamond and/or high-density phase boron nitride, and a rake angle of a portion involved in cutting on the rake face of the high-hardness sintered body. becomes positive, and the end of the positive rake face is blocked by a wall made of a high-hardness sintered body. This is a high-hardness sintered cutting tool that is characterized by having a groove.

That is, the present invention provides a tool comprising a sintered body at the cutting edge of a negative indexable tip, in which a groove of a specific shape is provided on the rake face of the sintered body, and a part of the groove is formed on the positive rake face, Most of the above problems are solved by allowing the remaining portion to function as a chip breaker.

Hereinafter, the present invention will be explained with reference to the drawings.

Figures 1a, 1b, and 1cll show how to cut a high-hardness sintered body according to the present invention, which has a positive rake angle and a chip breaker by providing a groove on the cutting edge of a sintered body tool that originally has a negative-shaped cutting edge. Fig. 1a is a plan view of the tool, Fig. 1b is a side view, and Fig. 1c is an enlarged sectional view of a cross section perpendicular to the groove provided on the cutting edge. ' is a sintered body, 2.2' is an alloy, 3.3' is a groove with a rake face and a chip breaker wall, 4°4' is a cemented carbide bonded to the sintered body during sintering, and 5゜5' is the rake face part of the groove, 6,6
′ is the part corresponding to the wall surface of the chip breaker in the groove, 7′ is the silver solder that adheres the cemented carbide and alloy to the sintered body during sintering, and 8 is the sintered body before the groove 3 is provided. A line indicating the position of the rake face, α is the vertical knife angle of the sintered body before the groove 3 is provided, β is the vertical knife angle after the groove 3 is provided, T
is the angle formed by the rake face part of the groove 3' provided in the sintered body, 5' and the part 6' of the chip breaker, and δ is the rake angle. Since the rake angle δ is 0° before it is provided, the rake angle δ is 0°. The rake angle after the groove 3' is provided is δ = β - 90°, and as is clear from the figures, β is an acute angle, so for example, if β = 85°, the rake angle 6 is 5＠. Become. In order to form the grooves 3', it is generally possible to grind the sintered body with a Dunyamond grindstone to provide a groove in the desired shape and shape. , any processing method may be used.

T indicates the angle at which the rake face 6 portion 5' of the groove and the chip breaker portion 6' intersect, but if it is an acute angle, machining is difficult. 90 is difficult and the obtuse angle 4th angle is also effective as a chip and small player.
It is appropriate to set the angle in the range from 150° to 150°. The actual value within this range can be selected as appropriate depending on the cutting conditions and the hardness, type, shape, etc. of the workpiece material, but a person skilled in the art with general knowledge about cutting can Easy to set up. In Fig. 1c, the part where the rake face part 5' of the groove intersects with the part 6' of the chip breaker is shown to intersect at right angles, but in reality, due to grinding with the Dunniamond grindstone, a small It will be connected to a circular arc with curvature or a curved line with a curve of 1. However, it is not necessary that the part be connected with a circular arc or a curve similar to a circular arc with a right angle or an extremely small curvature, and in fact it should be avoided. There is also a chip breaker.
In order not to damage the wall surface of the portion 6, it is preferable that that portion be formed with a curved surface.If the cross-sectional shape of the groove 3' in FIG. It is more appropriate to form the wall surface of the chip breaker portion 6 into a curved shape, for example, in a three-shape shape, in order to reduce damage to the wall surface of the chip breaker portion 6' and to smooth the flow of chips.

In the above explanation, the shape of the cutting edge is negative, but the shape of the cutting edge suitable for applying the present invention is not limited to the negative shape. It is also applicable when it is desired to increase the rake angle of the shape, or when it is desired to include a chip breaker.

Figures 2a, 2b, and 2c show other examples of the high-hardness sintered cutting tool in which the cross-sectional shape of the groove is three-shaped and the horizontal rake angle is also set, and Figure 2a shows the cutting edge. A partially enlarged plan view, FIG. 2b is a view along the line A-A in FIG. 2a, and FIG. 2c is a view along the line B-B in FIG. 2a, la.

lb, lc are sintered bodies, 2a, 2b, 2c are base metals,
3a and 3bs are three-shaped grooves, 4b and 4c are cemented carbide bonded to the sintered body during sintering, and 7b and 7c are cemented carbide and alloy bonded to the sintered body during sintering. Silver solder, δb is rake angle, - is horizontal rake angle, L is groove 3b
6b is the length of the rake face portion, Ls is the length from the cutting edge of the sintered body to the opposite end, and 6b is a portion of the chip breaker of the groove.

To provide a horizontal rake angle of 1, when carving the grooves 3a and 3b with a Dunyamond grindstone, set the rake face of the chip at a horizontal rake angle of 1.
2a, 2.
In the case of Figures b and 2c, the horizontal rake angle is set for right hand, but to make left hand, it is only necessary to set the slope in the opposite direction.The length of the rake face part of the groove is determined by cutting. If the depth of cut is D, it must always be L>D, L<
In case D, the sintered body 1b cuts into the uncut part of the rigid material with a very large negative angle, which creates a large cutting resistance, and there is a high possibility that the tool will be extremely worn out or break. Since it is large, it must be avoided, so from L to D
The value obtained by subtracting the value must always be set to be positive, but Ls is the length Ls from the cutting edge of the sintered body to the opposite end.
If the value Lm-L, which is obtained by subtracting L from L, is too small, the thickness of the sintered part that supports the side surface of the chip breaker part 6b in the groove will be small, and the chip breaker will resist the resistance when changing the direction of chips. There is a risk that it will not cut and be destroyed. On the other hand, L
-If D is too small, chips will form quickly after cutting! It is generally preferable to set L in the range of 1.20 to IOD, since large resistance is generated due to the need to change the direction, which may adversely affect cutting or break the chip breaker portion 6a. , to what extent should the value of L be set?
The value of the rake angle varies depending on the type, hardness, shape, cutting conditions, etc. of the workpiece and is difficult to determine, but it can be determined by those skilled in the art who have general knowledge about cutting. , can be easily set according to the above conditions.

FIG. 3 shows the indexable tip according to the present invention,
FIG. 3 is a plan view showing an example in which the boundary between the rake face 5^ and the chip breaker face 6^ and the wall surface of the chip breaker 6A are curved in an arc shape. Figures 1a, 1b, 1c and 2
In the examples shown in Figures a, 2b, and 2c, the part is a flat plane, and when processing with a Dunyamond grindstone, a typical method is to cut almost perpendicularly to the rake face with a straight type grindstone, for example. On the other hand, the shape shown in Fig. 3 is mainly machined using a cup-shaped grindstone in such a way that its outer circumference is machined against the wall surface of the chip breaker 6^. This is a typical processing method. Whether the wall surface of the chip breaker is flat or curved does not make much difference in carrying out the present invention, except in special cases, and rather it can be determined based on the convenience of processing.

Also, for convenience, we have explained tools with a throw-away tip shape, but in practice, we are not limited to throw-away tips, but tools that braze a sintered body to the handle, i.e. It can be applied in exactly the same way to bytes.

(Example) Hereinafter, the present invention will be specifically explained with reference to Examples and Comparative Examples.

Example: An indexable insert having a cutting edge equipped with a sintered body containing 70 volumes x of high-density boron nitride, which is a mixture of wurtzite boron nitride and cubic boron nitride. A tool in the shape of TllG332 with a groove that also functions as a chip breaker was prepared. The sintered body attached to the cutting edge has a side length of 4.5 mm, a high-density phase boron nitride portion with a thickness of 0.8 mm, and is bonded to the high-density phase boron nitride portion while sintering at the same time. The cemented carbide part had a thickness of 1.7 cm, and was bonded to a TNG332-shaped cemented carbide indexable tip by silver brazing after providing a step corresponding to the size of the sintered body part. The shape of the groove on the cutting edge is such that the length of the rake face is 1.8 mm from the cutting edge, the rake angle is 5@, the right-hand side rake angle is 3@, and the wall surface of the chip breaker is It was made to rise from the rake face part with an radius of about 0.5 square meters.

In this case, the cross section of the groove has a shape corresponding to a so-called 3-shape. Further, a chamfer with a width of 0.1 m and an angle of 15° was provided at the peripheral edge of the blade, and the corner where the chamfer and the flank intersected was connected by an arc with a radius of 0.02 m.

The work material is SCM440 steel and Rockwell C scale 58.
It has a hardness of 150 m in outer diameter, 450 m in length, and has four grooves with a quadrilateral cross section of 20 m width and 10 depths distributed equally on the circumference on the surface along the longitudinal axis. I prepared what I had set up. The cutting conditions were a circumferential speed of 180 m/min and a depth of cut of 0.
Dry cutting was performed at a distance of 5 m and a feed rate of 0.18 cm/rotation.

The height of the above TNG332 type throw-away tip is 32mm.
(2) Cutting was carried out by attaching it to a holder with a width of 25 mm, a cutting angle of 15 degrees, a rake angle of -5@, and a rake angle of -6 degrees. In this case, the actual rake angle is -5° + 5° = o" due to the grooves for providing the rake angle and chip breaker according to the present invention on the indexable insert, and the side rake angle is -6" + 36 = -3°.

By repeatedly cutting the surface of a rigid material under the above conditions, the cutting performance of the indexable insert with grooves according to the present invention was evaluated, mainly regarding the life of the insert based on the flow of chips and the surface roughness of the rigid material. It was measured. As a result, the chips are broken short by the action of the chip breaker throughout the entire cutting period, and if the life is defined as the surface roughness of the workpiece exceeding 5 μm, the life is determined by the total cutting time. It was 42 minutes. After cutting was completed, the surface of the sintered compact of the slow 7-way chip was observed using a solid III mirror with a magnification of 20x, and traces of chips flowing onto the surface of both the rake face and the wall of the chip breaker were observed. However, there was almost no damage, and it was clear that the tip of the blade had worn out and became serrated, resulting in a decrease in surface roughness and that it had reached the end of its life. Flank wear was 0.08 m.

Comparative Example A throw-away tip similar to that of Example was prepared, except that the rake face provided on the cutting edge and the groove that also served as a chip breaker were not provided. That is, the rake face of the sintered body was flat, and the peripheral edge of the blade was provided with a chamfer and a knot arc similar to the embodiment.

A cutting test was conducted using this tool under exactly the same conditions as in the example.

As a result, the total cutting time until the surface roughness exceeded 5 μ- was approximately 11 minutes, which was less than 173 minutes in the case of the example. Furthermore, when the cutting edge was observed using a stereomicroscope with a magnification of 20 times, it was found that there was a tear-like wear mark on the cutting edge that was about 1.3 cm wide and about 0.8 cm deep, and the flank wear was 0. It had reached 58m5. Reason why the performance was extremely low compared to the example □
This is thought to be because the negative angle of the cutting edge was too large, resulting in high cutting resistance, and the flow of chips remained at the cutting edge, further increasing the cutting resistance. Additionally, since there is no chip breaker, the chips are long and often become entangled with the cutting edge of the cutting tool or the rigid material.

(Effects of the Invention) A feature of the present invention is that in a tool comprising a sintered body at the cutting edge of a negative-shaped slow 7-way tip, a groove of a specific shape is provided on the rake face of the sintered body, and a part of the groove is By functioning as a positive rake face and the remaining part as a chip breaker, tool wear is significantly less compared to conventional ones, which means a significantly longer tool life. The strength does not decrease, the position of the chip breaker can be selected arbitrarily, the holder can be a holder for negative-shaped chips, and by simply machining a normal negative-shaped tool, it can be made to be equivalent to or better than a positive-shaped tool. This method has many advantages, such as being able to obtain a tool with the following effects and being economically advantageous because it is easy to manufacture.

[Brief explanation of drawings]

FIG. 1a is a plan view showing an embodiment of the present invention, FIG. 1b is a side view thereof, FIG. 1C is an enlarged cross-sectional view of the cutting edge, and FIG. 2a is a FIG. 2b is a plan view showing a cutting edge of another embodiment of the present invention; FIG. 2b is a sectional view taken along line AA in FIG. 2a, and FIG. 2c is a sectional view taken along line BB in FIG. 2a. FIG. 3 is a plan view according to the present invention. Ll' +1a+1b+1c+1^...Sintered body 2.
2', 2a, 2b, 2c, 2A... base metal 3.3'
, 3a, 3b, 3A...Groove with rake face and chip breaker wall 4.4', 4b, 4c...Cemented carbide 5.5', 5b sintered, specifically bonded to the sintered body , 5^... Rake face part of the groove 6.
6', 6b, 6A...Chip breaker part of groove 7.7', 7b, 7c...Silver solder 8...Rake face position α before groove is provided...Vertical cutter before groove is provided Angle β... Vertical knife angle of the groove mark T... Angle δ between the rake face of the groove and the chip breaker-wall surface
, δb... rake angle $... side rake angle 1, t' - sintered body Fig. 1c 3・t゛ - biographical n → - Fig. 2a
Figure 2b Figure 2C Figure 3

Claims (1)

[Claims] 1. In a high-hardness sintered cutting tool whose cutting edge is equipped with a sintered body containing Danyamond and/or high-density phase boron nitride, the rake angle of the part involved in cutting is positive on the rake face of the high-hardness sintered body. , and the end of the positive rake face is blocked by a wall made of a high-hardness sintered body, and the cross section perpendicular to the rake face and the wall has an approximately L-shape or J-shape. A high-hardness sintered cutting tool characterized by being provided with.