GB2157205A

GB2157205A - Cutting tools

Info

Publication number: GB2157205A
Application number: GB08508930A
Authority: GB
Inventors: Thomas Christopher Collins
Original assignee: Sandvik Ltd
Current assignee: Sandvik Ltd
Priority date: 1984-04-09
Filing date: 1985-04-04
Publication date: 1985-10-23
Also published as: GB8409109D0; GB2157205B; GB8508930D0

Abstract

A scarfing tool for trimming weld beads on welded metal tubes has a replaceable cutting insert (8) with alternative concave cutting edges (26) on a pair of opposite side faces (20) and flat extensions (28) at the ends of these cutting edges. The insert is secured in a seating (6) in a holder (2) by a screw (10) through a central hole (12) in the insert, the extensions of the non-operative cutting edge abutting a rear face (22) of the seating. The seating and the insert have complementary bottom faces (16, 32) with a V-form transverse cross-section to hold the insert more firmly against movement in the seating. <IMAGE>

Description

SPECIFICATION Cutting tools This invention relates to cutting tools for trimming the weld beads on welded metal tubes.

These tools, also sometimes known as scarfing tools, are required to operate in heavy duty conditions to, in effect, plane off the external bead of a weld running along an axial seam of a welded steel tube. They are therefore made with a brazed-on cutting tip ground to give a concave edge conforming to the radius of a curvature of the tube cross-section.

According to one aspect of the present invention, there is provided a tool comprising a holder and a replaceable cutting insert, the insert having concave cutting edges on a pair of opposite side faces, each said side face having co-planar lateral end extensions beyond said concave cutting edges for location against a rear face of a seating for the insert in the holder, a locking screw for securing the insert in said seating passing through a central aperture in the insert midway between said cutting edges.

According to another aspect of the invention, there is provided a replaceable cutting insert for such a tool.

Preferably, the insert has a bottom face with a downward projection extending transversely to said side faces supported in a complementary bottom face of the seating. In particular, said complementary faces may be so configured as to have a V-form cross-section in a plane parallel to said opposite side faces.

An example of the invention is shown in the accompanying drawings, wherein; Figures 1 to 3 are mutually transverse views of a tool according to the invention, and Figures 4 to 6 are mutually transverse views illustrating in more detail the cutting insert of the tool in Figs. 1 to 3.

The tool comprises a holder 2 with a rectangular section shank 4 having a seating 6 at its forward end for a replaceable cutting insert 8. The insert is secured by a locking screw 10 passing through a counter-sunk clearance hole 12 in the centre of the insert into a tapped bore 14 in the bottom face 16 of the seating. The insert is thereby clamped onto the seating bottom face, with its rear side face 20 located against an inclined rear face 22 of the seating, to be set at a top rake angle of 5 relative to the longitudinal axis of the shank.

The insert has a substantially rectangular plan form with corresponding front and rear side faces 20. In each face 20, a concave cutting edge 26 extends over some 80% of the face width between flat, co-planar end extensions 28. These side faces lie at 64 to the flat top face 30 of the insert. The bottom face of the insert is of V-form in transverse cross-section, with planar inclined portions 32 on each side of a central flat 34, said portions subtending an angle of 140 . The lateral side faces 36 of the insert are perpendicular to the top face 30.

The holder seating bottom face 16 has inclined portions providing a complementary V-form to that of the insert bottom face, and a transverse relief slot 42 separates the bottom face 16 from the rear face 22.

When the insert is secured by the locking screw, therefore, it is held firmly against rotation about the axis of the screw and against lateral displacement, by virtue of the engagement of the V-form faces 16, 32. Rearward displacement by the cutting forces acting on the insert is prevented by abutment of the flat extensions 28 at the rear face of the insert against the seating rear face 22, so holding the reserve concave cutting edge clear of the seating rear face.

In use, the tool is employed with a planing action to remove the axial weld bead on a welded steel tube in a single pass, the holder being inclined rearwards relative to the tube surface, so that the insert has a resultant top rake angle of 20 and a clearance angle of 6 .

1. A replaceable cutting insert having concave cutting edges on a pair of opposite side faces, each said side face having co-planar lateral end extensions beyond said concave cutting edge for abutment of the insert against a rear location, midway between said cutting edges the insert having a central aperture to receive a securing element.

2. An insert according to claim 1 having a bottom face with a downward projection extending transversely to said side faces for engagement with a supporting seating.

3. An insert according to claim 2 wherein said projection has a V-from cross-section in a plane parallel to said side faces.

4. An insert according to claim 3 wherein said V-form cross-section projection extends from a further pair of side faces transverse to the side faces carrying said cutting edges.

5. An insert according to any one of claims 2 to 4 wherein said projection has a flat forming its lowermost extremity.

6. A tool comprising a holder and a replaceable cutting insert, the insert having concave cutting edges on a pair of opposite side faces, each said side face having co-planar lateral end extensions beyond said concave cutting edges for location against a rear face of a seating for the insert in the holder, a securing element for securing the insert in said seating passing through a central aperture in the insert midway between said cutting edges.

7. A tool according to claim 6 wherein the insert has a bottom face with a downward projection extending transversely to said side faces and supported in a complementary bottom face of the seating.

8. A tool according to claim 7 wherein said complementary faces are so configured as to have a V-form cross-section in a plane parallel to said opposite side faces.

9. A tool according to claim 7 or claim 8 wherein the seating has a clearance relief between

**WARNING** end of DESC field may overlap start of CLMS **.

Claims

**WARNING** start of CLMS field may overlap end of DESC **. SPECIFICATION Cutting tools This invention relates to cutting tools for trimming the weld beads on welded metal tubes. These tools, also sometimes known as scarfing tools, are required to operate in heavy duty conditions to, in effect, plane off the external bead of a weld running along an axial seam of a welded steel tube. They are therefore made with a brazed-on cutting tip ground to give a concave edge conforming to the radius of a curvature of the tube cross-section. According to one aspect of the present invention, there is provided a tool comprising a holder and a replaceable cutting insert, the insert having concave cutting edges on a pair of opposite side faces, each said side face having co-planar lateral end extensions beyond said concave cutting edges for location against a rear face of a seating for the insert in the holder, a locking screw for securing the insert in said seating passing through a central aperture in the insert midway between said cutting edges. According to another aspect of the invention, there is provided a replaceable cutting insert for such a tool. Preferably, the insert has a bottom face with a downward projection extending transversely to said side faces supported in a complementary bottom face of the seating. In particular, said complementary faces may be so configured as to have a V-form cross-section in a plane parallel to said opposite side faces. An example of the invention is shown in the accompanying drawings, wherein; Figures 1 to 3 are mutually transverse views of a tool according to the invention, and Figures 4 to 6 are mutually transverse views illustrating in more detail the cutting insert of the tool in Figs. 1 to 3. The tool comprises a holder 2 with a rectangular section shank 4 having a seating 6 at its forward end for a replaceable cutting insert 8. The insert is secured by a locking screw 10 passing through a counter-sunk clearance hole 12 in the centre of the insert into a tapped bore 14 in the bottom face 16 of the seating. The insert is thereby clamped onto the seating bottom face, with its rear side face 20 located against an inclined rear face 22 of the seating, to be set at a top rake angle of 5 relative to the longitudinal axis of the shank. The insert has a substantially rectangular plan form with corresponding front and rear side faces 20. In each face 20, a concave cutting edge 26 extends over some 80% of the face width between flat, co-planar end extensions 28. These side faces lie at 64 to the flat top face 30 of the insert. The bottom face of the insert is of V-form in transverse cross-section, with planar inclined portions 32 on each side of a central flat 34, said portions subtending an angle of 140 . The lateral side faces 36 of the insert are perpendicular to the top face 30. The holder seating bottom face 16 has inclined portions providing a complementary V-form to that of the insert bottom face, and a transverse relief slot 42 separates the bottom face 16 from the rear face 22. When the insert is secured by the locking screw, therefore, it is held firmly against rotation about the axis of the screw and against lateral displacement, by virtue of the engagement of the V-form faces 16, 32. Rearward displacement by the cutting forces acting on the insert is prevented by abutment of the flat extensions 28 at the rear face of the insert against the seating rear face 22, so holding the reserve concave cutting edge clear of the seating rear face. In use, the tool is employed with a planing action to remove the axial weld bead on a welded steel tube in a single pass, the holder being inclined rearwards relative to the tube surface, so that the insert has a resultant top rake angle of 20 and a clearance angle of 6 . CLAIMS

9. A tool according to claim 7 or claim 8 wherein the seating has a clearance relief between the seating bottom and rear faces.

10. A replaceable cutting insert constructed and arranged for use substantially as described herein with reference to the accompanying drawings.

11. A scarfing tool constructed and arranged for use substantially as described herein with reference to the accompanying drawings.