JP2877434B2 - Solid material cutting tool - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a cutting tool made of a solid material, comprising a tool body and a cemented carbide cutting insert, which is fixedly secured to the tool body by brazing. It relates to a cutting tool. The invention also relates to a cutting insert.

When the cutting tool according to the invention is used for cutting relatively hard solid materials, for example sandstone, the cutting insert is subjected to a very large force, which produces a rotational movement which is A tensile stress is generated on a specific surface portion of the cutting tip. Also, this rotational movement is consequently transmitted to the braze joint.

(Prior art)

Cemented carbide cutting inserts subjected to high bending stresses must have a high toughness, i.e., a lower hardness compared to cutting inserts which are basically subjected to compressive stresses. In cutting mineral and asphalt, relatively high lateral forces are generated. Therefore, cutting inserts of relatively low hardness and high Co (cobalt) content are selected for cutting mineral and asphalt. High Co content is also beneficial in reducing brazing stress.

The wear resistance of the cutting inserts described above is consequently low and is not desirable with regard to service life. Therefore, it is common to select large cutting inserts with large amounts of cemented carbide for mineral and asphalt cutting. In this way, the bending stress is dealt with, and the life of the tool is made to be an acceptable length.

In conventional cutting tools for cutting minerals and asphalt, this high-capacity cutting insert is fixed in a steel tool blank. In this configuration, the cutting insert is not subjected to excessively high stresses. However, such a design means that the blank steel surrounding the insert comes into immediate contact with the workpiece minerals and asphalt.
In particular, during mineral engineering, sparks can occur where contact between the mineral and the steel can create a very dangerous situation (eg, in mines with flammable gases). Contact between the cemented carbide insert and the mineral does not produce sparks under normal conditions.

Since cemented carbide inserts for cutting minerals and asphalt have a relatively large volume,
The tool itself becomes larger. This means that a very powerful machine is needed to carry the tool.

As mentioned above, the rotational movement acting on the cutting insert is transmitted to the braze joint. Conventional braze joints between the insert and the tool body are typically of substantially constant wall thickness. This means that the outer peripheral portion of the brazing joint absorbs the rotational moment well.

In particular, in mineral cutting, technically and economically cuttable materials are a problem. The technically machinable material is a hard material that can be machined by a cutting action, and the economically machinable material is a hard material that can be machined by a cutting action that is more economical than other methods.

[Object of the invention]

It is an object of the present invention to provide such a tool and a cutting insert which require relatively little energy for cutting mineral or asphalt and exhibit high wear resistance. A preferred example of the tool has a braze joint which has a high degree of active absorption of the rotational moment acting on the insert. As a result, harder materials can be considered as economically cuttable. The tool of the present invention has a high degree of avoidance of spark generation during machining.

[Configuration of the invention]

In accordance with the present invention, there is provided a tool body (10) having a support surface, typically as a solid material cutting tool, and a cutting insert having a shoulder for resting on the support surface and a generally conical point. The solid material cutting tool, wherein the insert is fixedly secured to the tool main body, wherein the cutting insert (14) has an intermediate portion as viewed in the axial direction thereof. A circumferentially extending annular recess (18) around which the cutting insert comprises a cemented carbide core (15), a cemented carbide intermediate layer (16) surrounding the core and a cemented carbide surface layer (17). ), Wherein the surface layer, the intermediate layer and the core all comprise WC (α phase) and a binder phase (β phase) based on at least one of cobalt, nickel and iron.
, The core further contains an η phase, the intermediate layer and the surface layer are substantially free of an η phase, and the binder phase content of the surface layer is the binder phase in the insert. Wherein the binder phase content of the intermediate layer is greater than the apparent content of the binder phase in the insert.

The η phase content of the insert core (15) is 2 to 60 vo.
l.% is preferred, and the apparent content of the binder phase of the insert (14) is preferably 8 to 20 wt.%.

〔Example〕

In FIG. 1, a cutting drum 10 (only partially shown)
Carries a number of holders 11, each of which supports a tool 12 for cutting solid material. The cutting drum 10 is rotated in the direction indicated by the arrow 13. When the tool 12 is involved in work material, the cutting insert 14 of the tool 12 is subjected to a normal force F _N and the tangential force F _T.

When working on very hard materials, the normal force F _N becomes significantly larger than the tangential force F _T. This normal force F _N can be up to four times the tangential force F _T. In this case, it is recognized that a portion of the insert surface experiences a high degree of tensile stress.

To deal with this high tensile stress, EP 0182
The use of special cemented carbides as disclosed in 759 and 0247985 is required. Therefore, these patent publications are referred to herein as reference material of the present invention.

The cutting insert 14 shown in FIG. 3 has a core 15 of cemented carbide containing an eta phase. The core 15 is surrounded by an intermediate layer 16 of high cobalt containing cemented carbide without eta phase. There is a surface layer on it
17 which consist of low cobalt containing cemented carbide without η phase (eta phase). The insert 14 has an annular concave portion 18 at an intermediate portion thereof.

The thickness of the surface layer is 0.8 to 4 times, preferably 1 to 3 times the thickness of the intermediate layer 16.

The core 15 and the cobalt-rich intermediate layer 16 have a higher thermal expansion property than the surface layer 17. This means that the surface layer 17 receives a high compressive stress. Difference in thermal expansion, that is, surface layer 17
Difference in cobalt content between the and the remaining insert part,
The larger the value, the larger the compressive stress of the surface layer 17. The binder phase content of the surface layer 17 is 0.1 to 0.9 times the apparent binder phase content of the insert 14, preferably 0.2 to 0.7 times.
It is twice. The binder phase content of the mid layer 16
1.2 to 3 times, preferably 1.4 to 3 times the apparent binder phase content of
2.5 times.

From the above, it can be seen that the higher the apparent cobalt content of the insert, the greater the compressive stress of the surface layer. This is shown in the graph of FIG.

Core of cemented carbide containing eta (η) phase 15
It should be noted that is tough, hard and wear-resistant. The core 15 is composed of an intermediate layer 16 having no eta phase and containing high cobalt and a surface layer 17 having no eta phase and receiving a high compressive stress.
A cutting insert 14 which meets the above-mentioned requirements discussed for the cutting of minerals and asphalt, i.e. a cutting which requires a relatively low cutting force and has a relatively high wear resistance. Provide inserts.

The graph of FIG. 5 shows the hardness distribution of the cutting insert according to the invention and of a standard cemented carbide insert, also having an apparent cobalt content of 15% by weight. The measurements were taken from the insert surface to the center. From FIG. 5, it can be seen that the insert 14 of the present invention is approximately 1.
It has a relatively high hardness up to 5 mm, and this surface layer 17
Have a low cobalt content. The mid layer 16 has a high cobalt content and a relatively low hardness. The hardness of the core 15 becomes relatively high again.

Standard cemented carbide cutting insert is 5th
It has a certain hardness as shown in the figure.

With respect to the three types of cutting inserts, the parameters of wear were tested against the parameters of cutting length. The result is the sixth
Shown in the figure.

Type A cutting inserts are designed with the contours shown in FIG. 3, but are made of standard type cemented carbide. Type B cutting inserts are designed with a conventional profile for mineral cutting (FIG. 7). Type C
The cutting insert according to the present invention has the outer shape and configuration shown in FIG.

As can be seen from FIG. 7, insert A had 100% wear after a cut length of about 190 m. Insert B was about 80% worn after a cutting length of about 375m. Insert C is about 940m
Was about 50% worn after cutting length. Along with this fact, inserts A and C weigh 80 g whereas insert B weighs 150 g, ie insert B has twice the volume of each of inserts A and C. Point out that.

For those skilled in the art, the results in FIG. 7 are very surprising. Compared to conventional cutting inserts for cutting minerals and asphalt, the cutting inserts according to the invention have relatively large axial projections (FIG. 2). The insert composition shown in FIG. 3 allows relatively large tensile stresses and bending moments acting on the insert to be accommodated by relatively large insert axial protrusions.

Another advantage of the tool of the present invention is that less dust is generated during cutting compared to the conventional tool, that is, the distribution of the chip grain size in the insert of the present invention is shifted to a larger grain size as compared to the insert B. (Fig. 7).
The reason lies in the combination of the high wear resistance of the insert and the outer shape.

FIGS. 8 and 9 show a preferred embodiment of the brazing joint 19. The brazing joint 19 is inserted into the tool body 10 and the insert
Coordinates between 14 The tool body has a recess 20 for receiving the insert 14.

According to the embodiment, this recess 20 is formed by a central longitudinal axis 22 of the tool.
The recess has a conical surface 23 extending from the bottom 21 toward the outer periphery of the tool body 10. This conical surface portion 23 has an axis
Symmetric about 22. The recess 20 further has an annular surface 24 extending in the longitudinal direction of the tool. In the conical surface part 23,
An annular groove is formed. This groove 25 is used to fix the insert 14 in the recess 20.

The insert 14 has, according to one embodiment, a flat bottom surface 26 designed to be positioned over the recess bottom portion 21 in the insert mounting position.

The cutting insert 14 has a bottom surface up to its cylindrical outer peripheral surface 28.
Includes a conical surface portion 27 extending from 26. This outer peripheral surface 28
Defines the maximum diameter of the insert 14.

The conical surface 27 comprises a number of spaced apart buttons 29 which cooperate with the grooves 25 in the mounting position of the insert 14. These buttons 29 and grooves 25 ensure that the insert is seated in the correct position before brazing is performed.

As shown in FIG. 8, the conical surface 23 of the recess 20 and the conical surface 27 of the insert define an angle .alpha.
{4} is preferred. Moreover, the interval between the two conical surface portions 23 and 27 is enlarged (diverged) in the direction of the tool outer periphery.

From FIG. 9, the distance between the bottom surfaces 21 and 26 is small in the example disclosed herein.

When brazing, the tool body 10 and the insert 14 are coaxially arranged as shown in FIGS. That is, they have a common longitudinal axis 22.

Brazing is performed in this state, and it is preferable to use a copper-based brazing alloy. It is also preferable to use a vacuum brazing method. The upper surface of the braze joint 19 is designated at 30 in FIG.

Due to the included angle α between the conical surfaces 23, 27, the brazing joint 19 has a generally wedge-shaped cross section in a plane including the tool axis. The thickness of the braze joint 19 increases toward the outer periphery of the insert 14.

The above-described design of the braze joint 19 is effective in that the entire joint between the conical surfaces 23, 27 absorbs the rotational moment acting on the insert. The braze joint 19 receives a tensile force on one side and a compressive force on the diametrically opposite side. The most difficult force to deal with is, of course, the tensile force.

In a word, the function of the brazing joint according to the present invention can be said to be equivalent to a large number of means such as elastic springs 31, 32, 33 working. In this case, the outer part of the braze joint, viewed in the radial direction, is more strongly pulled / compressed than the inner part. Although the equivalent springs 31-33 have different degrees of tension / compression, they exert substantially the same force due to the different spring lengths. This is shown in the graph of FIG. In this figure, the vertical axis represents the force F and the horizontal axis represents the elongation E. The brazing joint shown in FIG. According to the conventional method, the equivalent springs 31 to 33 receive a pulling force which becomes negative on the graph. Each spring has the same tensile force, but different elongation. Of course, this theory is not entirely satisfactory in practice, but the principle is important.

According to, but not limited to, preferred dimensions of the braze joint, the joint is 0.7 mm thick in the region of spring 31 and in the region of spring 33
0.3mm thick. The diameter of the insert 14 is 24 mm as measured on the outer peripheral surface 28 of the cylinder.

In addition, the above-mentioned brazing is a cutting insert according to the present invention.
Not limited to use with 14.

[Brief description of the drawings]

1 is a partial explanatory view showing a cutting drum of an excavator, FIG. 2 is an enlarged explanatory view showing a part of a tool carried on the cutting drum, FIG. 3 is a cross-sectional view of a cutting insert according to the present invention,
FIG. 4 is a graph showing the variation of the compressive stress of the surface layer due to the cobalt content, FIG. 5 is a graph showing the relationship between the distance from the surface and the hardness of the cutting insert of the present invention and the standard product,
FIG. 6 is a graph showing the relationship between wear and cutting length of various cutting inserts, FIG. 7 is a side view showing a head of a type B cutting insert, and FIG. 8 is a present invention having a brazed joint in a preferred embodiment. 9 is a partially cutaway side view showing a tool according to the present invention, and FIG. 9 is an enlarged partial explanatory view of FIG. In the figure: 10 ... cutting drum (tool body), 11 ... holder, 12 ... tool, 14 ... cutting insert, 15 ... core, 16 ... intermediate layer, 17 ... surface layer, 18 ... annular Concave part, 19 ... brazing joint, 20 ... concave part, 21 ... flat bottom part, 22 ... central axis, 23 ... conical surface part, 24 ... annular surface part, 25 ... groove, 26 ... bottom surface, 27 …… Conical surface part, 28 …… Cylinder outer surface, 29 …… Button.

Continuation of the front page (72) Inventor Bengt Anders Ausberg Es-803 21 Gävle, En. Cape Mangatan 42 A (56) Reference JP-A-59-187475 (JP, A) JP-A-61-179846 (JP, A) JP-A-60-71106 (JP, A) JP-A 63-161288 (JP, A) (58) Fields investigated (Int. Cl. ⁶ , DB name) B23B 27/14 E21C 35/18 C22C 29/08

Claims (18)

(57) [Claims] 1. A solid material cutting tool comprising a tool body (10) having a support surface, a cutting insert having a shoulder for resting on the support surface and a generally conical point. In such a solid material cutting tool, which is fixedly secured to the tool body, an intermediate portion of the cutting insert (14) when viewed in the axial direction is a circumference around the cutting insert. The cutting insert comprises a cemented carbide core (15), a cemented carbide intermediate layer (16) surrounding the core, and a cemented carbide surface layer (17). The surface layer, the intermediate layer and the core are all WC (α phase) and a binder phase (β phase) based on at least one of cobalt, nickel and iron
And the core further contains an η phase, the intermediate layer and the surface layer have substantially no η phase, and the binder phase content of the surface layer is in the insert. A solid material cutting tool wherein the apparent content of the binder phase is lower than the apparent content of the binder phase in the insert, and the binder phase content of the intermediate layer is higher than the apparent content of the binder phase in the insert. 2. The solid material cutting tool according to claim 1, wherein the η phase content of the core is 2 to 60 vol.%. 3. The binder phase having an apparent content of 8 to 20 wt.%.
The solid material cutting tool according to claim 1, wherein: 4. The binder layer content of the surface layer is 0.1 to 0.9 times the apparent content of the binder phase in the insert, and the binder phase content of the intermediate layer is the same as that of the binder phase in the insert. The solid material cutting tool according to claim 1, wherein the tool content is 1.2 to 3 times the hanging content. 5. The binder layer content of the surface layer is 0.2 to 0.7 times the apparent content of the binder phase in the insert, and the binder phase content of the intermediate layer is the apparent phase content of the binder phase in the insert. The solid material cutting tool according to claim 4, wherein the tool content is 1.4 to 2.5 times the hanging content. 6. The thickness of the surface layer is from 0.8 to 0.8 of the thickness of the intermediate layer.
The solid material cutting tool according to claim 1, wherein the tool is quadrupled. 7. The thickness of the surface layer is 1 to 3 of the thickness of the intermediate layer.
7. The solid material cutting tool according to claim 6, wherein the tool is doubled. 8. The solid material cutting tool according to claim 1, wherein the cutting insert is secured to the tool body by brazing. 9. The patent, wherein the braze joint (19) between the insert (14) and the tool body (12) has a wall thickness which at least partially increases in a direction from the center of the insert toward the outer periphery of the insert. The solid material cutting tool according to claim 8. 10. The solid material cutting tool according to claim 9, wherein said braze joint has a generally wedge-shaped cross section in a plane containing the tool axis. 11. A cemented carbide cutting insert adapted to be secured to a support surface of a tool body (10), wherein the insert rests on the generally conical point and the support surface. An annular recess (18) in which an intermediate portion of the cutting insert (14) when viewed in the axial direction extends circumferentially around the cutting insert. Wherein the cutting insert comprises a cemented carbide core (15), a cemented carbide intermediate layer (16) surrounding the core, and a cemented carbide surface layer (17), wherein the surface layer, the intermediate layer and the core are Both are WC (α phase) and binder phase (β phase) based on at least one of cobalt, nickel and iron
And the core further contains an η phase, the intermediate layer and the surface layer have substantially no η phase, and the binder phase content of the surface layer is in the insert. A cemented carbide cutting insert, wherein the apparent content of the binder phase is less than the apparent content of the binder phase in the insert, and the binder phase content of the intermediate layer is greater than the apparent content of the binder phase in the insert. 12. The cutting insert according to claim 11, wherein the η phase content of the core is 2 to 60 vol.%. 13. The binder phase having an apparent content of 8 to 20 w.t.
12. The cutting insert according to claim 11, which is%. 14. The binder layer content of the surface layer is 0.1 to 0.9 times the apparent content of the binder phase in the insert, and the binder phase content of the intermediate layer is the content of the binder phase in the insert. 12. The cutting insert according to claim 11, wherein the cutting content is 1.2 to 3 times the hanging content. 15. The binder layer content of the surface layer is 0.2 to 0.7 times the apparent content of the binder phase in the insert, and the binder phase content of the intermediate layer is the content of the binder phase in the insert. 15. The cutting insert according to claim 14, wherein the cutting content is 1.4 to 2.5 times the hanging content. 16. The thickness of the surface layer is 0.8% of the thickness of the intermediate layer.
12. The cutting insert according to claim 11, wherein the cutting insert is up to 4 times. 17. The thickness of the surface layer is 1 to 1 of the thickness of the intermediate layer.
17. The cutting insert according to claim 16, wherein the cutting insert is tripled. 18. The cutting insert according to claim 11, wherein the cutting insert is secured to the tool body by brazing.