GB2156254A

GB2156254A - Milling cutter with alternative rake inserts

Info

Publication number: GB2156254A
Application number: GB08507923A
Authority: GB
Inventors: Kenneth Atkins
Original assignee: Brock & Co Ltd L & T I
Current assignee: Brock & Co Ltd L & T I
Priority date: 1984-03-28
Filing date: 1985-03-27
Publication date: 1985-10-09
Also published as: GB8507923D0; GB8407946D0

Abstract

A cutting insert 4 for clamping to a seat 3 in a cutter body 2 of a milling cutter or other rotatable cutting tool is in the form of a block having a radially-inner end locating face 9 and a pair of adjacent edge-locating faces to be abutted against respective locating faces of a seat for the insert 4. The insert 4 also has a pair of alternative faces 11, 12 of which one 11, when the insert 4 has been located in its seat 3, will be inclined at an angle to a radius of the cutter body about its axis of rotation equal to the required angle of radial rake alpha with respect to a cutting tip 5 and the other 12 of which will be spaced at 17 from an adjacent face of the cutter body 2. <IMAGE>

Description

SPECIFICATION Milling Cutter The invention relates to a milling cutter or like rotatable cutting tool of the kind, hereinafter called the kind described, having a cutter body having at least one radially-outwardly extending cutting flute having at its radially-outer periphery a seat for receiving a cutting insert to be clamped to the seat.

By providing separate cutting inserts, the latter can readily be replaced when the cutting edge or edges have become blunt and also the cutting inserts can be made of a hard metal such as sintered carbide or high speed steel, whereasthe cutter body can be made of a cheaper or softer steel or other metal.

Hitherto, each insert has been correctly located in its seat by abutting the radial rake face or faces of the insert against correspondingly inclined faces in the seat. As different workpiece materials require different angles of radial rake, it has been necessary hitherto for the complete milling cutter, i.e., the cutter body and the cutting insert or inserts, to be changed when a change in radial rake angle is dictated by a change of workpiece material. An object of the invention is to provide a universal cutter body on which a range of inserts having different radial rake angles can be accommodated, thereby enabling the user to change only the cutting insert or inserts and not the cutter body when he changes from one workpiece material to another.

According to the invention, a cutting insert, for clamping to a seat in a cutter body of a milling or other cutter of the kind described, comprises a block having a radially-inner end locating face and a pair of adjacent edge-locating faces to be abutted against respective locating faces of a seat for the insert on a cutter body and, extending outwardly from the block with respect to the cutter body, a pair of alternative faces one of which when the insert has been located in its seat will be inclined at an angle to a radius of the cutter body about its axis of rotation to the required angle of radial rake and the other of which will be spaced from an adjacent face of the cutter body.

By providing the locating block extending inwardly of the radial rake-defining faces, a selected insert or inserts from a range of inserts each having radial rake-defining faces of different rake angles can be fitted on a universal or standard cutter body as the radial rake-defining faces will not be obstructed by adjacent faces on the cutter body.

The insert provided by this invention is preferably clamped to the seat in the cutter body by a clamping screw passed through the insert from the radially outerface thereof and having a head recessed into the insert and therefore the insert is provided with a through hole for receiving the shank of the clamping screw and a counterbored or countersunk recess in the radially-outer end face of the insert for receiving the head of the clamping screw.

The whole insert may be an integral block of hard metal, e.g., a sintered carbide or high speed steel.

The invention also includes a cutter body having at least one radially-outward-extending cutting flute having at its radially-outer periphery a seat to which the aforesaid cutting insert is to be clamped, the seat having a radially-outwardly-facing end face and a pair of adjacent edge locating faces against which corresponding faces on the insert are to be abutted.

The faces in the seat engageable by the pair of adjacent edge-locating faces of the block may both be fixed with respect to the block. Alternatively one of the said seat faces may by adjustable relatively to the cutter body, whereby adjustment of the block relatively to the cutter body can be effected. Conveniently the adjustable seat face may be an adjustable stop mounted on the cutter body and positioned to abut against the adjacent edge-locating face of the block. The adjustable stop may be an eccentrically-mounted cylindrical cam mounted for rotation on the cutter body. Locating means may be provided to lock the cam in a required locating position.

The invention also includes the complete cutter comprising the cutter body, one or more inserts and clamping means therefor as hereinbefore set out.

By way of example, two embodiments of milling cutter in accordance with the invention are now described with reference to the accompanying drawings, in which: Figure 1 is an end view of the first embodiment of the milling cutter; Figure 2 is a view in the direction of arrow II in Figure 1 of an insert only, drawn to a larger scale; Figure 3 is a view of the insert in the direction of arrow Ill in Figure 2 and also indicating in outline the cutting flute of the cutter body and the seat therein in which the insert is seated; Figure 4 is a side view of the milling cutter in the direction of arrow IV in Figure 1; Figure 5 is a side view of the radially-outer end of a cutting flute in the second embodiment of the milling cutter, and Figure 6 is a view in the direction of arrow V1 in Figure 5.

Figures 1 and 4 show the first embodiment of milling cutter and this is similar in general form to a conventional milling cutter in that it includes a cutter body comprising a hub 1 and one or more radiallyoutwardly extending cutting flutes 2, each having a seat 3 in which there is a replaceable cutting insert 4 having a cutting tip 5. One of the flutes 2 is shown in outline and to a larger scale in Figure 3. Referring to Figure 3, each seat shown by arrow 3 provides a radially-outwardly-facing locating face 6; an upstanding side locating face 7 and an adjacent upstanding end locating face 18 (see Figure 4) extending from the faces 6 and 7 parallel to the plane of Figure 3.The insert shown by arrow 4 comprises a block 8 having a radially-inner end face 9 which abuts and locates on the face 6 of the seat 3; an upstanding side locating face 10 which abuts and locates on the face 7 of the seat 3, and one of a pair of adjacent upstanding end locating faces 15, 16 (see Figure 2) parallel to the plane of the Figure 3 and which abuts and locates on the corresponding end locating face 18 of the seat 3. The block 8 has a radially-outwardly projecting portion having a pair of parallel radial rake-defining faces 11, 12 of which one, 11, is used in the position shown to provide the cutting tip 5. The other face 12 is an alternative face which is brought into use by turning the insert 4 through 1800 about the centre-line X shown in Figures 3 and 2.The insert 4 comprising the block 8 and the outwardly projecting portion is formed integrally and is made from a hard metal, e.g., sintered carbide or high speed steel.

The insert is clamped in its seat by a screw having a shankwhich passes through a central throughhole 13 in the insert 4 into a screw-threaded hole in the flute 2 in the cutter body. The screw has a head which is located in a counterbored or countersunk recess 14 co-axial with the hole 13. Thus there is no fixing clamp which will interfere with the cutting action of the insert 4 or the flow of cut material from the tip 5.

When the insert 4 has been located and clamped in the seat, the radial rake-defining face 11 will be held at the correct angle to define the radial rake angle a (in this example 22 ) and the clearance angle P (in this example 8 ). The radial rake angle which is required is different for different workpiece materials. Hitherto, where one of the rake-defining faces 11, 12 has been used as a locating face, only an insert having a rake-defining face inclined at the same angle as the corresponding seat face would be fitted to a cutter body. Thus a different cutter body and inserts were required for each different workpiece material.In the cutter body of this invention there is a recess 17 radially beyond the seat face 7 providing a clearance space alongside the rake-defining face 12 which is not being used.

This is possible because the location occurs at the position of the block face 10 and the seat face 7 and not at the rake-defining face 12. It is therefore possible to fit inserts having rake-defining faces 11 and 12 providing different rake angles selected from a range of which a typical angle is indicated by angle y in Figure 3. Therefore a standard cutter body can be fitted with inserts which have rake-defining faces 11 and 12 selected to result in a radial rake angle y suitable for the particular workpiece material. Thus the user merely has to change the inserts and not the complete milling cutter, as hitherto. The simple screw fixing makes the clamping of the inserts simple and quick and the provision of the locating faces enables the inserts always to be correctly located when the clamping screws have been tightened.The seats could be inclined in the axial direction of the cutter body and so an axial rake angle can be provided as well as the radial rake angle.

In the second embodiment shown in Figures 5 and 6, the insert 4 of each cutting flute 2 is not located against a fixed end locating locating face 18 as in the first embodiment. Instead, an adjustable end stop in the form of cylindrical cam 19 mounted eccentrically on a shaft 20 engages against one or other of the end locating faces 15, 16 of the insert 4.

The cam 19 has a hexagonal, or other non-circular, socket 21 in its end face to receive a key, whereby the cam 19 is turned eccentrically about the axis of rotation of the shaft 20. The eccentric movement of the cam 19 causes end-wise adjustment of the insert 4 after the latter has been loosened in its seat by slackening of the central clamping screw. The shaft 20 and therefore the cam 19, can be locked in a position to which the cam has been set by a grub screw 22 mounted in a screw-threaded hole 23 in an end face of the flute 2 of the milling cutter. Except for the provision of the end-wise adjustment of each insert 4 on the respective cutting flute 2, the milling cutter is similar to that shown in Figures 1--4.

Although the insert 4 is shown in this embodiment as being adjustable by an eccentric cam 19, other methods of end-wise or sideways adjustment of the insert in its seat may be provided.

Claims

1. A cutting insert for clamping to a seat in a cutter body of a milling or other rotatable cutter of the kind described, comprising a block having a radiallyinner end locating face and a pair of adjacent edge-locating faces to be abutted against respective locating faces of a seat for the insert on a cutter body and, extending outwardly from the block with respect to the cutter body, a pair of alternative faces one of which when the insert has been located in its seat will be inclined at an angle to a radius of the cutter body about its axis of rotation equal to the required angle of radial rake and the other of which will be spaced from an adjacent face of the cutter body.

2. An insert as claimed in Claim 1 having a through-hole extending between its end faces for receiving the shank of a clamping screw and having a counterbored or countersunk recess in its radiallyouter end face for receiving the head of the clamping screw.

3. An insert as claimed in Claim 1 or 2 comprising an integral block of hard metal or sintered carbide.

4. A cutter body for a rotatable cutting tool of the kind described having at least one radiallyoutwardly-extending cutting flute having at its radially-outer periphery a seat to which an insert according to any preceding claim is to be clamped, the seat having a radially-outwardly-facing end face and a pair of adjacent edge locating faces against which corresponding faces on the insert are to be abutted.

5. A cutter body as claimed in Claim 4 in which the faces in the seat engageable by the pair of adjacent edge-locating faces of the block are both fixed with respect to the block.

6. A cutter body as claimed in Claim 4 in which one of the faces in the seat engageable by an edge-locating face of the block is adjustable relatively to the cutter body, whereby adjustment of the block relatively to the cutter body can be effected.

7. A cutter body as claimed in Claim 6 in which the adjustable seat face is an adjustable stop mounted on the cutter body and positioned to abut against the adjacent edge-locating face of the block.

8. A cutter body as claimed in Claim 7 in which the adjustable stop is an eccentrically-mounted cylindrical cam mounted for rotation on the cutter body.

9. A cutter body as claimed in Claim 8 in which locking means are provided to lock the cam in a required locating position.

10. A rotatable cutting tool of the kind described comprising a cutter body as claimed in any one of Claims 4--9 and one or more cutting inserts as claimed in any one of Claims 1-3.

11. A milling cutter substantially as described herein with reference to Figures 1--4 or Figure 5 and 6 of the accompanying drawings.

12. A cutting insert for a milling cutter as claimed in Claim 11 and shown in Figures 2 and 3 of the accompanying drawings.