CA1224028A - Excavating tool - Google Patents
Excavating toolInfo
- Publication number
- CA1224028A CA1224028A CA000455027A CA455027A CA1224028A CA 1224028 A CA1224028 A CA 1224028A CA 000455027 A CA000455027 A CA 000455027A CA 455027 A CA455027 A CA 455027A CA 1224028 A CA1224028 A CA 1224028A
- Authority
- CA
- Canada
- Prior art keywords
- conical tip
- generally conical
- tool according
- tip portion
- concave surface
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired
Links
Abstract
Abstract The invention relates to a tool for breaking or excavating of hard material, such as asphalt. The tool comprises a cutting insert (11) secured to a tool body (10). For purposes of main-taining the required cutting force low while ensuring that the risk is low that the cutting insert (11) will get loose the cutting insert (11) is provided with a concave portion (171) between the tip portion (12) of the cutting insert and a rear shoulder (13) thereon.
Description
Excavating tool The present invention relates to a tool for breaking or ex-cavating of hard material, such as asphal-t, comprising a tool body and a cutting inser-t secured thereto, for instance by brazing. The cutting insert is formed with a generally conical -tip por-tion and provided with a shoulder which is intended to res-t against a sllpporting surface on the tool body.
The purpose of the inven-tion is-to provide a tool of the above type which requires a low cutting force at the same time as it is ensured -that -the risk is low -that the cut-ting insert will get loose even during working in wear resis-tan-t material.
This and other objects have been attained by giving the inven-tion the characterizing features stated in the appending claims.
The inven-tion is described in de-tail in the following with re-ference to the accompanying drawings, in which one embodiment is shown by way of example. It is to be understood that -this embodiment is only illustra-tive of the inven-tion and that va-rious modifications thereof may be made within the scope of the claims.
In the drawings, Fig. l shows a side view, part]y in sec-tion, of a prior art -tool for breaking hard ma-terial.
Fig. 2 shows a side view, party in section, of another prior art -tool.
Fig. 3 shows one embodimen-t of a tool according to the inven--tion.
Fig. L~ shows on an enlarged scale -the cutting insert in -the tool shown in Fig. 3.
:~z~o~
Corresponding details in -the various figures have been given the same reference numeral.
Tools of -the type in question are usually mounted rotatably in a tool holder, which in its turn is at-tached to an excavating machine, such as a road planing machine or a mining machine.
Due to its rotation the tool is self-sharpening. The machine migh-t be of the -type disclosed in EP-A-25421.
F'or breaking or excavating of wear resistant material, for instance for milling in poured asphalt (mastic), tools are used of -the type shown in Fig. 1. This tool comprises a tool body 10 and a cutting insert 11 of hard metal. The cutting insert 11 is provided with a conical tip portion 12 and a shoulder 13, which is in-tended to rest against a supporting surface 14 on -the tool body 10. The rear contact surface 20 of the shoulder 13 is brazed to the supporting surface 14. The cutting insert 11 is provided with a conical intermediate por-tion 15 which is located between the -tip portion 12 and the shoulder 13. The portion 15 protects the portion of the -tool body 10 - the tool body being made of s-teel - surrounding the cutting insert 11 from such wear that would cause -the cutting insert 11 to ge-t loose. When wear resistant material is excavated, for instance during milling in poured asphalt, -the tip portion 12 becomes blunt-ended upon some wear of the cutting insert 11. This wear increases the required cutting force.When milling in poured asphalt the increase of the required cutting force might even have the result -tha-t the road planing machine does not manage -to rota-te -the cu-t-ter drum upon which the tools are mounted.
One way of decreasing the cutting force required for worn tools would be -to use a tool of the type shown in Fig. 2. How-ever, this should mean that the portion 16 of the tool body 10 surrounding -the cutting insert 11 rapidly would be abraded, thereby causing -the cutting insert 11 to get loose. Thus, cutting inser-ts of the type shown in Fig. 2 are suitable for 1~4~32~3 use solely where the hard metal determines the life of the -tool, for ins-tance at milling in concrete.
As shown in Figs. 3 and Ll the cutting insert 11 in a tool according to the inven-tion is provided with an in-term~diate portion 17 between the tip portion 12 and the shoulder 13;
said intermediate portion comprising a concave portion 171.
Due to -this i-t is achieved that -the required cutting force is main-tained low even when the -tip portion 12 becomes worn.
Due to this design it is also ensured that the steel in the tool body 10 surrounding the cutting insert is protected against premature abrasion; this protec-tion being provided by the concave portion 17 and the shoulder 13.
According to a preferred embodiment the portion 17 comprises a circular-cylindrical portion 1711 located adjacen-t to the tip portion 12. Further in this embodiment the distance "a"
from -the transition 18 between the tip por-tion 12 and the portion 17 to -the radially outermos-t portion 19 of the rear contact surface 20 of the shoulder 13 is larger than the dis-tance "b" from the transi-tion 18 to the axially forwardmost portion of the tip portion 12; said rear contac-t surface being intended to rest agains-t the supporting surface lLI of the -tool body 10.
F'urther, in -the illustra-ted embodiment, the smallest diame-ter "d" of the concave portion 17 is smaller -than the sum of the above-defined dis-tances "a" and "b". The concave portion 171 is provided wi-th a constant radius of curvature, which is in -the same order as half -the above-men-tioned smallest diameter "d", preferably somewhat smaller -than said diameter.
The envelope surface of the cylindrical portion 17 extends tangential to -the arc-sllaped portion 17 .
3~
~2~4~:8 In the illustrated embodiment -the cutting insert is provided with a rear portion projecting rearwardly from -the shoulder 13. The end surface of this portion is planar. It might, however, be recessed, for instance half-sphericalor of the general W-shape illustrated in Swedish Patent Application No. 8400269-0. The bottom of -the recess might rest against a correspondingly shaped protrusion on the tool body, or, alternatively, the recess might provide a cavi-ty.
In a further modification -the cutting insert might be made without a rear projection. The rear end surface of the cutting insert, i.e. the end surface of the shoulder, and the cooperating front surface of the -tool body might be designed according -to any of the above alternatives.
The purpose of the inven-tion is-to provide a tool of the above type which requires a low cutting force at the same time as it is ensured -that -the risk is low -that the cut-ting insert will get loose even during working in wear resis-tan-t material.
This and other objects have been attained by giving the inven-tion the characterizing features stated in the appending claims.
The inven-tion is described in de-tail in the following with re-ference to the accompanying drawings, in which one embodiment is shown by way of example. It is to be understood that -this embodiment is only illustra-tive of the inven-tion and that va-rious modifications thereof may be made within the scope of the claims.
In the drawings, Fig. l shows a side view, part]y in sec-tion, of a prior art -tool for breaking hard ma-terial.
Fig. 2 shows a side view, party in section, of another prior art -tool.
Fig. 3 shows one embodimen-t of a tool according to the inven--tion.
Fig. L~ shows on an enlarged scale -the cutting insert in -the tool shown in Fig. 3.
:~z~o~
Corresponding details in -the various figures have been given the same reference numeral.
Tools of -the type in question are usually mounted rotatably in a tool holder, which in its turn is at-tached to an excavating machine, such as a road planing machine or a mining machine.
Due to its rotation the tool is self-sharpening. The machine migh-t be of the -type disclosed in EP-A-25421.
F'or breaking or excavating of wear resistant material, for instance for milling in poured asphalt (mastic), tools are used of -the type shown in Fig. 1. This tool comprises a tool body 10 and a cutting insert 11 of hard metal. The cutting insert 11 is provided with a conical tip portion 12 and a shoulder 13, which is in-tended to rest against a supporting surface 14 on -the tool body 10. The rear contact surface 20 of the shoulder 13 is brazed to the supporting surface 14. The cutting insert 11 is provided with a conical intermediate por-tion 15 which is located between the -tip portion 12 and the shoulder 13. The portion 15 protects the portion of the -tool body 10 - the tool body being made of s-teel - surrounding the cutting insert 11 from such wear that would cause -the cutting insert 11 to ge-t loose. When wear resistant material is excavated, for instance during milling in poured asphalt, -the tip portion 12 becomes blunt-ended upon some wear of the cutting insert 11. This wear increases the required cutting force.When milling in poured asphalt the increase of the required cutting force might even have the result -tha-t the road planing machine does not manage -to rota-te -the cu-t-ter drum upon which the tools are mounted.
One way of decreasing the cutting force required for worn tools would be -to use a tool of the type shown in Fig. 2. How-ever, this should mean that the portion 16 of the tool body 10 surrounding -the cutting insert 11 rapidly would be abraded, thereby causing -the cutting insert 11 to get loose. Thus, cutting inser-ts of the type shown in Fig. 2 are suitable for 1~4~32~3 use solely where the hard metal determines the life of the -tool, for ins-tance at milling in concrete.
As shown in Figs. 3 and Ll the cutting insert 11 in a tool according to the inven-tion is provided with an in-term~diate portion 17 between the tip portion 12 and the shoulder 13;
said intermediate portion comprising a concave portion 171.
Due to -this i-t is achieved that -the required cutting force is main-tained low even when the -tip portion 12 becomes worn.
Due to this design it is also ensured that the steel in the tool body 10 surrounding the cutting insert is protected against premature abrasion; this protec-tion being provided by the concave portion 17 and the shoulder 13.
According to a preferred embodiment the portion 17 comprises a circular-cylindrical portion 1711 located adjacen-t to the tip portion 12. Further in this embodiment the distance "a"
from -the transition 18 between the tip por-tion 12 and the portion 17 to -the radially outermos-t portion 19 of the rear contact surface 20 of the shoulder 13 is larger than the dis-tance "b" from the transi-tion 18 to the axially forwardmost portion of the tip portion 12; said rear contac-t surface being intended to rest agains-t the supporting surface lLI of the -tool body 10.
F'urther, in -the illustra-ted embodiment, the smallest diame-ter "d" of the concave portion 17 is smaller -than the sum of the above-defined dis-tances "a" and "b". The concave portion 171 is provided wi-th a constant radius of curvature, which is in -the same order as half -the above-men-tioned smallest diameter "d", preferably somewhat smaller -than said diameter.
The envelope surface of the cylindrical portion 17 extends tangential to -the arc-sllaped portion 17 .
3~
~2~4~:8 In the illustrated embodiment -the cutting insert is provided with a rear portion projecting rearwardly from -the shoulder 13. The end surface of this portion is planar. It might, however, be recessed, for instance half-sphericalor of the general W-shape illustrated in Swedish Patent Application No. 8400269-0. The bottom of -the recess might rest against a correspondingly shaped protrusion on the tool body, or, alternatively, the recess might provide a cavi-ty.
In a further modification -the cutting insert might be made without a rear projection. The rear end surface of the cutting insert, i.e. the end surface of the shoulder, and the cooperating front surface of the -tool body might be designed according -to any of the above alternatives.
Claims (10)
1. A rotatable excavating tool for breaking hard material, comprising:
an elongated tool body having an end with a diameter and a supporting surface; and a cutting insert of hard metal having a generally conical tip portion, an elongated intermediate portion integral with and extending from the generally conical tip portion, defining an abrupt transition from the generally conical tip portion, and having a maximum diameter which is substantially less than the diameter of the tool body end, a concave surface portion axially spaced from the generally conical tip portion, joining the elongated intermediate portion, extending radially outwardly therefrom, and being integral with the elongated intermediate portion, a shoulder with a diameter substantially larger than the maximum diameter of the elongated intermediate portion, and integrally joining the concave surface portion, and a rearwardly facing contact surface attached to the supporting surface of the tool body.
an elongated tool body having an end with a diameter and a supporting surface; and a cutting insert of hard metal having a generally conical tip portion, an elongated intermediate portion integral with and extending from the generally conical tip portion, defining an abrupt transition from the generally conical tip portion, and having a maximum diameter which is substantially less than the diameter of the tool body end, a concave surface portion axially spaced from the generally conical tip portion, joining the elongated intermediate portion, extending radially outwardly therefrom, and being integral with the elongated intermediate portion, a shoulder with a diameter substantially larger than the maximum diameter of the elongated intermediate portion, and integrally joining the concave surface portion, and a rearwardly facing contact surface attached to the supporting surface of the tool body.
2. A tool according to claim 1, wherein the elongated intermediate portion comprises a generally cylindrical portion located adjacent to the conical tip portion.
3. A tool according to claim 1, wherein the distance (a) from the abrupt transition between the generally conical tip portion and the elongated intermediate portion to the radially outermost portion of the rearwardly facing contact surface of the shoulder is larger than the distance (b) from said abrupt transition to the axially forwardmost portion of the generally conical tip portion.
4. A tool according to claim 3, wherein the smallest diameter (d) of the concave surface portion is smaller than the distance (a + b) from the axially forwardmost portion of the generally conical tip portion to the radially outer-most portion of the rearwardly facing contact surface of the shoulder.
5. A tool according to claim 1, wherein the concave surface portion has a constant radius of curvature.
6. A tool according to claim 2, wherein the distance (a) from the abrupt transition between the generally conical tip portion and the intermediate surface portion to the radially outermost portion of the rearwardly facing contact surface of the shoulder is larger than the distance (b) from said abrupt transition to the axially forwardmost portion of the generally conical tip portion.
7. A tool according to claim 6, wherein the smallest diameter (d) of the concave surface portion is smaller than the distance (a + b) from the axially forwardmost portion of the generally conical tip portion to the radially outermost portion of the rearwardly facing contact surface of the shoulder.
8. A tool according to claim 2, wherein the concave surface portion has a constant radius of curvature.
9. A tool according to claim 3, wherein the concave surface portion has a constant radius of curvature.
10. A tool according to claim 4, wherein the concave surface portion has a constant radius of curvature.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA000455027A CA1224028A (en) | 1983-03-23 | 1984-05-24 | Excavating tool |
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| SE8301584A SE450259C (en) | 1983-03-23 | 1983-03-23 | Tools for breaking or cutting solid materials such as asphalt |
| CA000455027A CA1224028A (en) | 1983-03-23 | 1984-05-24 | Excavating tool |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1224028A true CA1224028A (en) | 1987-07-14 |
Family
ID=25670397
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000455027A Expired CA1224028A (en) | 1983-03-23 | 1984-05-24 | Excavating tool |
Country Status (1)
| Country | Link |
|---|---|
| CA (1) | CA1224028A (en) |
-
1984
- 1984-05-24 CA CA000455027A patent/CA1224028A/en not_active Expired
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| MKEX | Expiry |