GB2332161A - Reuse of disposable cutter inserts - Google Patents

Abstract

A method of re-using a cutting insert 44 having a plurality of cutting edges E1-E8 comprises taking an insert 44 which has been mounted on one form of holder and previously used for a turning operation on a machine tool whereby some of its edges E1, E2, E5 and E6 have been worn and re-mounting it in an alternative holder to present an unworn cutting edge E3, E4, E7 and for a different machining operation. The holder 10 for mounting such an insert 44 comprises a mounting surface 14 having means thereon for attaching the insert 44 to the holder 10 and a location surface 38 against which a side of the insert 44 lies to orientate the insert 44 correctly in the holder 10. The holder may-be provided with a coolant passageway.

Description

2332161 1 REUSE OF A DISPOSABLE CUTTING INSERT The invention relates to

the reuse of a disposable cutting insert and is particularly concerned with the reuse of a cutting insert used in a turning operation.

Disposable cutting inserts have been used in turning and milling operations for many years. Typically, an insert is formed from sintered tungsten carbide and is either square or rhomboidal in plan. The insert is mounted on a holder which orientates the insert in a manner appropriate for the machining operation required. The use of inserts is advantageous as eight cutting edges are available for machining, one at each comer on each face of the insert. Fig 8 illustrates a typical rhomboidal insert. The insert 44 comprises two rhomboidal faces 45 with four side walls 46. The edge between a face 45 and a side wall 46 is used as a cutting surface for machining. Fig 8 shows an insert having eight cutting edges E I, E2, E3, E4, E5, E6, E7, E8. The edges E 1, E2, E5, E6 are defined adjacent the acute comers of the insert and are suitable for turning operations and the edges E3, E4, E7, E8 are suitable for milling operations. Normally, after the edges suitable for turning have wom out, the insert is discarded. That wastes four potentially useful cutting edges E3, E4, E7, E8.

An object of the present invention is to provide for the reuse of an insert previously used in a turning operation.

2 According to one aspect of the invention there is provided a method of reusing a cutting insert having a plurality of cutting edges comprising taking an insert which has been mounted on one form of holder and previously used for a turning operation on a machine tool whereby some of its cutting edges have become worn, providing an alternative holder for the insert and mounting the insert on the alternative holder so as to present an unworn cutting edge for a different machining operation.

The invention enables cutting edges of the insert which are not usually useable for a turning operation to be used, say, for face milling. In that way, the cutting insert can be used until all of its edges have become worn, thereby greatly increasing the working life of the insert and saving costs as a result.

The method preferably includes mounting a plurality of used inserts on the alternative holder to enable the different machining operation to be performed. In such a case, the method may include arranging the used inserts on the alternative holder to provide a suitable rake angle.

In a preferred embodiment, the alternative holder is a rotary holder.

According to a second aspect of the invention there is provided a holder for mounting an insert previously used for a turning operation, the holder comprising a mounting surface having means thereon for attaching the insert to the holder, and a location 3 surface against which a side of the insert lies to orientate the insert correctly in the holder.

Preferably, the mounting surface is arranged to position the insert in order to provided a suitable rake angle. The holder may be a rotary holder. In such a case, the insert is preferably arranged in the holder so as to be disposed with a negative or positive radial angle and a negative or positive axial angle. Preferably the mounting surface is arranged to position the insert to provide either or both of said negative or positive angles.

The insert, when mounted on the holder, preferably has one of the nonworn edges projecting beyond an extremity of the holder to provide a cutting tip.

In a preferred embodiment, the holder has a plurality of spaced apart mounting surfaces for respective inserts.

The holder may be formed with a passageway for coolant. The passageway preferably includes a first portion, for example in the form of a gallery, which may extend around an axis of rotation of the holder and a second portion extending outwardly from the first portion so as to provide an outlet for the coolant adjacent an insert on the holder. A plurality of second portions may be provided which provided 4 respective outlets for coolant adjacent associated inserts on the holder. The passageway may be arranged to receive coolant from a feed passageway preferably formed in an adaptor for carrying the holder.

The cutting insert is preferably retained on the holder by means of a screw. Preferably the screw is received in a screw threaded ferrule. The screw most preferably includes a head and a screw threaded shank and is arranged whereby the head engages a part of the holder spaced from the insert and the shank extends through a bore in the holder and through a bore in the insert to engage the screw threaded ferrule. The ferrule is preferably received on a shoulder in the bore in the insert.

The head of the screw preferably abuts a radiused shoulder in the bore in the holder.

The reuse of a cutting insert in accordance with the invention and a holder therefor will now be described by way of example with reference to the accompanying drawings in which:- Fig I is an axial cross-section through a holder in accordance with the invention showing a previously used insert in position thereon, the holder being mounted on an adaptor, Fig 2 is an end view of the holder shown in Fig 1 looking in the direction of arrow II in Fig 1 and shown partly in cross- section, Fig 3 is a side view of the holder shown in Fig 2 looking in the direction of arrow III in Fig 2 and showing a single insert mounting surface, Fig 4 is a cross-section through the mounting surface of Fig 3 on line IV- IV in Fig 3, Fig 5 is a cross-section through one of the inserts mounted on the holder as shown in Fig 2 and drawn to a larger scale, Fig 6 is an elevation of an insert looking in the direction of arrow 111 in Fig 2 and drawn to a larger scale.

Fig 7 is a cross section through an insert mounted on a holder showing an alternative mounting arrangement drawn to a large scale.

Fig 8 is a perspective view of an insert showing cutting edges thereof.

Fig 9 is a view similar to Fig 4 of an alternative form of holder in accordance with the invention, and Fig 6 is a view similar to Fig 3 of the holder of Fig 9.

Looking at Figs 1 and 2, a holder 10 comprises a cutter body 12 formed, in the present example, with five mounting surfaces in the form of angularly spaced identical seats 14. The angular spacing is irregular to avoid production of resonance vibrations. Each of the seats is formed at one end of an associated chip chamber 16 which has an inclined surface 18 formed with an outlet 20 for coolant fluid as described below.

The cutter body 12 has an axial bore 22 formed therein coaxial with an axis of rotation 24 of the body. The axial bore 22 receives a retaining screw 25 for fixing the cutter body 12 to an adaptor 26 by which the cutter body is mounted on a machine tool (not shown) such as a face milling machine. The cutter body 12 has central bore 28 therein which receives a hollow spigot-like end 30 of the adaptor 26. With the adaptor 26 in position as shown in Fig 1, an annular gallery 32 is defined between the free end of the spigot-like end 30 and the fixing screw 25. Two passageways 34 for coolant extend through the spigot-like adaptor 26 and lead from a main coolant feed 36 in the adaptor 26 to the annular gallery 32. Five passageways 37 lead from the gallery 32 and terminate at the outlets 20.

Looking at Figs 3 and 4, the shape of one of the seats 14 can be seen in detail. The 7 seat 14 is inclined away from the direction of rotation (indicated by arrow R in Figs 2 and 4) to provide an axial angle A of around -5 to 8 degrees. Also, the seat 14 lies on a plane 14a which is offset from the axis of rotation 24 of the holder 10. The seat 14 lies adjacent two location surfaces 38 which are inclined relative to each other and which are perpendicular to the seat 14. Lower edges 3 8a of the location surfaces 3 8 are defined by cusp-like edges of an open sided bore 40. A screw-threaded bore 42 is formed in the seat 14 for receiving a retaining screw 43 (see Fig 1) for an insert 44.

The insert 44 is rhomboidal in shape and is similar to that described previously in relation to Fig 8. The insert 44 is of a known kind and is designed to be used for turning operations. During such an operation, the E I, E2, E5, E6 are used one at a time until they are all wom and the edges are no longer of use for further turning. The insert 44 is then removed from its holder (not shown but of known kind) and is positioned on the body 12 with one face 45 against a flat anvil 52 placed against the seat 14 and two of its unused edges E3, E4 lying between the cusp- like edges 38a of the bore 40. Side walls 46 of the insert lie against the location surfaces 38. As will be appreciated, that leaves the two remaining unused cutting edges E7, E8 projecting above the seat as viewed in Fig 5 with the outermost cutting edge E8 providing a cutting surface. The insert 44 and the anvil 52 are formed with respective through bores 14a and 52a respectively for the retaining screw 43 which screws intu a screw-threaded bore 56 formed in the body 12 adjacent the seat 14. The negative 8 axial angle A of the seat 14 and, therefore of the anvil 52, and the positioning of the insert 44 by the anvil 52 forwardly of the seat 14 in the direction of rotation R means that the outermost edge E8 of the insert 44 present a positive radial angle B of around 0 to 12 degrees with respect to a radial line C for milling a workpiece indicated at W.

In Fig 7, an insert 44 is shown mounted to a holder 10 substantially similar to that shown in Figs 1 to 4. The holder 10 includes a plurality of seats 14. Each seat 14 is substantially similar to the seats shown in Figs 1 to 4, comprising a flat anvil 52 securely fastened to the holder 10 by means of a retaining screw 5 8 which screws into the bore 56. The screw 58 itself has a through bore 60 which allows passage of an insert retaining screw 62. The insert retaining screw 62 extends through a bore 64 in the holder 10 and is received or in a screw threaded ferrule 66 which retains the insert 44. The head of the insert retaining screw 62 retains the insert 44. The head of the insert retaining screw 62 retains the insert 44. The head of the insert retaining screw 62 engages against a surface 68 defining a partial radius in section. That arrangement results in more secure retention of the insert 44 than by simply screwing into a screwthreaded bore as shown in Figs 1 to 4.

Figs 9 and 10 illustrate a holder 10 similar in many respects to the holder in Figs 1 to 7 and parts corresponding to parts in Figs 1 to 7 carry the same reference numerals.

9 The holder 10 of Figs 9 and 10 comprises a cutter body 12 with mounting surfaces in the form of angularly spaced seats 14. The holder 10 does not include the coolant system and the mounting seats 14 are arranged to allow the inserts 44 to be mounted directly on the seats 14 without the use of anvils 52. Either of the mounting methods envisaged in Figs 1 to 7 are appropriate but in the version shown the insert 44 is mounted by screwing a screw through the insert into the screw threaded bore 42 formed in the holder beneath each seat 14.

The invention enables inserts designed for use in turning operations to be reused in a milling operation rather than being thrown away when their usefulness for turning has come to an end. Not only does the invention save costs by effectively prolonging the working life of the insert but saves the user purchasing holders specially designed for holding throwaway milling cutter inserts which are suitable only for milling operations.

Claims (1)

1. A method of re-using a cutting insert having a plurality of cutting edges comprising taking an insert which has been mounted on one form of holder and previously used for a turning operation on a machine tool whereby some of its cutting edges have become worn, providing an alternative holder for the insert and mounting the insert on the alternative holder so as to present an unworn cutting edge for a different machining operation.

   A method of re-using a cutting insert according to claim 1 in which a plurality of used inserts are mounted on the alternative holder to enable the different machining operation to be performed.

   3.

   A method of re-using a cutting insert according to claim 2 in which the method includes arranging the used insertspn the alternative holder to provide a suitable rake angle.

   4. A method of re-using a cutting insert according to any of claims 1 to 3 in which the alternative holder is a rotary holder.- 5. A holder for mounting an insert previously used for a turning operation, the holder comprising a mounting surface having means thereon for attaching the insert to the holder, and a location surface against which a side of the insert lies to orientate the insert correctly in the holder.

   6. A holder according to claim 5 in which the mounting surface is arranged to position the insert in order to provide a suitable rake.

   .' 11 A holder according to claim 5 or 6 in which the holder is a rotary holder.

   1 8. A holder according to claim 7 in which the insert is arranged in the holder so as to be disposed with a negative or positive radial angle and a negative or positive axial angle.

   9. A holder according to claim 8 in which the mounting surface is arranged to position the insert to provide either or both of said negative or positive angles.

   10. A holder according to any of claims 5 to 9 in which the insert, when mounted on the holder, has one of the non-worn edges projecting beyond an extremity of the holder to provide a cutting tip.

   11. A holder according to any of claims.5 to 10 in which the holder has a plurality of spaced apart mounting surfaces for respective inserts.

   12. A ',,-,older according to any of claims 5 to 11 in which the holder is Z formed with a passageway for coolant.

   13.

   '. 'nclder according to claim 11 in which the passageway includes a first portion which extends around an axis of rotation of the holder and a second portion extending outwardly from the first portion so as to provide an outlet for the coolant adjacent an insert on the holder.

   14. A holder according to claim 13 in which a plurality of second portions 12 are provided which provide respective outlets for coolant adjacent associated inserts on the holder.

   1 A holder according to claim 12, 13 or 14 in which the passageway is arranged to receive coolant from a feed passageway preferably formed in an adaptor for carrying the holder.

   16. A holder according to any of claims 5 to 15 in which the cutting insert is retained on the holder by means of a screw.

   17. A holder according to claim 16 in which the screw is received in a screw threaded ferrule.

   18. A holder according to claim 17 in which the screw includes a head and a screw threaded shank and is arranged whereby the head engages a part of the holder spaced from the insert and the shank extends through a bore in the holder and throuQh a bore in the insert to engage the screw threaded ferrule.

   A holder according to claim 17 or 18 in which the ferrule is received on a shoulder in the bore in the insert.

   20. A holder according to any of claims 16 to 19 in which the head of the screw abuts a radiused shoulder in the bore in the holder.