GB2084056A

GB2084056A - Internal surface adjustable cutting tool

Info

Publication number: GB2084056A
Application number: GB8127129A
Authority: GB
Original assignee: ELECTRO METALLURGIE
Current assignee: ELECTRO METALLURGIE
Priority date: 1980-09-15
Filing date: 1981-09-08
Publication date: 1982-04-07
Also published as: NL8104259A; IT8103526A0; CH642889A5; DE3135964C2; FR2490127A1; IT1168393B; DE3135964A1; FR2490127B1; GB2084056B; LU83621A1; BE890337A

Abstract

The tool is constituted by a body (1) provided externally with a plurality of lateral undercut portions (3) forming housings for removable cutting plates (4). Each one of the said housings (3) defines a radial supporting face (5) for the cutting plate, an angled rear abutment (6) and a second abutment. The plates are held by screws (4a) in oversize plate holes. The second abutment is constituted by the generating lines of a tapered member (8a) of a core (8) inside the body and coaxial to the axis of rotation of the tool, and is radially adjustable by adjusting the core axial position. The core is held by locking screws. <IMAGE>

Description

SPECIFICATION Reamer type cutting tool A cutting tool of the known milling-cutter type of which the invention is an improvement comprises a revolving body provided at one of its ends with a driving shank, and at its other end, with cutting plates joined to said body in appropriate housing.

Said recesses are constituted by undercut portions provided at regular intervals on the periphery of the body to define a surface contained substantially inside a radial plane of the body on which the cutting plate is secured by means of a through screw. Above the said surface, the said undercut portions define abutments, one of which is called "rear fixed point" i.e. situated on the side of the tool-driving shank and forming a predetermined angle with the axis of rotation of the tool, the other abutment being "internal" and therefore situated on the side of the axis of rotation, perpendicular to the first one when the cutting plate is square-shaped. When the cutting plate is secured by means of the said screw, not only is it firmly set on the support face, it also rests on the two abutments.Indeed, there exists, from construction, a slight misalignment between the axis of the tapping receiving the screw and the axis of the hole of the cutting plate which, when the screw is tightened, causes this multiple support. In this way, the cutting plate is accurately set on the said body and thus, firmly secured and well oriented. The diameter of the tool is then defined by the diameter of the circle traversing the outermost angle of each one of the cutting plates which projects outside the tool body.

It would however be advantageous, when conducting accurate machinings, to be able to adjust to a certain extent the value of this diameter. Tools permitting this adjustment are known. But none of them has a device for securing the cutting plate by means of a through screw. The cutting plate is either clamped between its upper face and its face, or immobilized by a lateral screw acting as a wedge.

It is the object of the present invention to propose a solution whereby the diameter of this type of tool can be adjusted with accuracy whilst retaining the system wherein the cutting plate is secured by means of a though screw, which system is an extremely simple one to use.

The invention proposes to this effect a cutting tool of the reamer type constituted by a revolving body externally comprising a plurality of lateral undercut portions forming housings for receiving projecting cutting plates, each one of the said housings defining a face contained inside a radial plane of said body to support the cutting plate, a first rear abutment, known as "fixed point", to hold the cutting plate in the axial direction and in a predetermined angular orientation with respect to the axis of the body, and a second internal abutment, perpendicularto the first, to hold the cutting plate in the radial direction, the said cutting plate being secured by means of a through screw perpendicular to the said support face.

According to one of the main characteristics of the invention the position of the second abutment is radially adjustable and is constituted by a generating line of a tapered member situated inside the body, co-axially thereto, and the position of which is adjustable with respect to the said body along their joint axis.

In one preferred embodiment of the invention, the tapered member is extended by a threaded cylindrical portion which cooperates with a tapping provided inside the body, in the same way as a nut and screw, forming means for adjusting the relative position of the tapered member and of the body.

Also, the said tapered member is extended by at least a cylindrical bearing guiding it inside a corresponding bore in the body.

Advantageously, the tool according to the invention comprises means for the relative locking and centering of the body and of the said tapered member constituted by at least three radial lock screws which are screwed into the body and are adapted to rest on the said bearing, and by secant screws for locking the said lock screws into position, which secant screws are borne by the said body and accessible from the said supporting surface of the cutting plate.

Finally the tapered member will comprise means for controlling its rotation(screwing-unscrewing) inside the tool body.

The invention will be more readily understood on reading the following description, with reference to the accompanying drawings in which: Figure 1 diagrammatically illustrates, one half of it a cross-section, and the other half an external view of one embodiment of the tool according to the invention; Figure 2 is a diagrammatical end view of Figure 1; Figure 3 is a diagram showing in detail the adjusting principle used in the invention; Figure 4 is a diagram showing part of Figure 2, and illustrating a variant embodiment thereof.

Referring first to Figures 1 and 2, there is shown a tool of the reamer or milling-cutter type comprising a revolving body 1 provided at one of its ends with known means for securing it to a membercontroll- ing its rotation (which could be a tapered shank of the Morse taper type) and at its other end with peripheral undercut portions 3, regularly distributed and forming housings for small cutting plates 4 fitted on the body 1. Said housings 3 in effect define a radial supporting surface 5 on which is set the cutting plate 4 by way of a special screw 4a, also known. Said surface is on a slightly lower level than the rest of the undercut portion forming the said housing and as a result defines a rear abutment 6 known as a fixed point for the cutting plate.Said abutment forms with the axis of rotation of the body 1 an angle of a predetermined value which determines the inclination of the cutting plate 4 with respect to the said axis, and in particular the inclination of its cutting edge 4b.

The body 1 of the tool is provided with a central bore 7 which intersects the said housings 3 at least opposite the cutting plate 4. Thus, the inner edge 4c of the cutting plate projects slightly inside the bore 7.

If the plate is rectangular, the angle formed by the said edge 4c with the revolving axis of the tool is complementary to the angle formed by the abutment 6 with the same axis.

The said bore 7 is designed to receive a central member 8 co-axial to the body 1 and known as "core" whose end portion 8a which is designed to be placed opposite the cutting plates 4 is tapered, the tapered end facing inwardly of the tool body, and the top angle being equal to twice the angle formed by the said edge 4c with the said axis.

Said core presents, extending from the tapered portion 8a, two cylindrical bearings 8b and 8c which cooperate with corresponding bearings 7a and 7b provided in the bore 7. Between these two bearings, the core 8 is threaded in 8dwhereas the bore 7 is tapped in 7c. The front part 7d of the bore 7, of larger diameter which intersects with the said housing 3, is also tapered.

Thus when the core 8 is screwed into the body 1 (or unscrewed), the part 8a is driven more or less deeply into the part 7d of the bore, and as a result, the tapered surface portion of the said part 8a is to a greater or lesser degree closer to the housing 3 or, in other words, to a greater or lesser degree away from the revolving axis. Said external surface, orto be more specific, certain of its generating lines situated opposite the cutting plates 4 constitute radial bearings for the cutting plates, which bearings are radially adjustable in relation to how deep the core is driven into the body 1.

It is to be noted to this effect that the movement of the cutting plate is allowed by a large enough clearance which exists between the body of the screw 4a and the hole provided in the cutting plate 4.

In addition, provision will have been made at construction for a minimum misalignment of the axes of that hole and of the tapping provided in the tool body which receives the screw so that in the position where the diameter of the cutting tool is adjusted to the smallest dimension, the multiple support effect is preserved when the screw 4a is tightened. It is thus clear that in doing so the fine adjustment of the diameter causes an increase of this misalignment within limits that are still acceptable to enable a good tightening, the screw head being able to elasticity to bend slightly on the axis of the body.

Figure 3 diagrammatically illustrates that as the tapered part 8a is driven deeper into the tool (arrow A), the cutting plates 4 move further away from the revolving axis of the tool (arrow B). But the adjusting range is limited, on the one hand by the gentle taper of the cone, and on the other hand, by the cutting plate securing means which only allow a relatively small difference between the outermost positions which the cutting plate can take along the abutment 6. Nonetheless, the adjusting range can reach half a millimetre over a bore diameter of about 100 mm.

To control the rotation (screwing or unscrewing) of the core 8, the holes 9 will have been provided on its external face 8eforfitting in a fork-spanner (not shown). Quite obviously, any other rotating control means could also be used.

The position of the core 8 having been determined, and the cutting plate 4 being then secured in their final position in relation to the diameter required, the core can then be locked by means of locking screws 10 (three minimum for balancing purposes) screwed radially into the body 1 until they reach, and rest on the bearing 8b of the core. Said locking screws 10, once tightened, (they can also be used to adjust the centering of the core 8 with respect to the body 1) are in turn fixed in position by means of a secant screw 11 which is accessible at the level of each housing 3 (see Figure 4).

The number of cutting plates which can be mounted on a body will depend on the use of the tool. For example, six cutting plates will be fitted for a roughing reamer and the locking screws 10 may perhaps be dispensed with, since the core is held in position by tightening the cutting plates on the body, whereas only three cutting plates will be used in a finishing reamer, with the locking screws being then needed to secure the core and constituting an extra means (added to the guide bearings 7a, 7b, 8b, 8c) of centering the core and as a result the cutting plates with respect to the revolving axis of the tool.

The invention is in no way limited to the description given hereinabove and on the contrary covers any variants which may be brought thereto without departing from the scope or the spirit thereof.

Claims

1. Reamer-type tool comprising a plurality of lateral undercut portions forming housing for receiving projecting cutting plates, each one of the said housing defining a face contained inside a radial plane of said body to support the cutting plate, a first rear abutment, known as "fixed point", to hold the cutting plate in the axial direction and in a predetermined angular orientation with respect to the axis of the body, and a second internal abutment, perpendicular to the first, to hold the cutting plate in the radial direction, the said cutting plate being secured by means of a through screw perpendicular to the said support face, wherein the position of the second abutment is radially adjustable and is constituted by a generating line of a tapered member situated inside the body, co-axially thereto, and the position of which is adjustable with respect to the said body along their joint axis.

2. Cutting tool according to claim 1, wherein the said tapered member is extended by a threaded cylindrical portion which cooperates with a tapping provided inside the body, in the same way as a nut and screw, forming means for adjusting the relative position of the tapered member and of the body.

3. Cutting tool according to claim 2, wherein the said tapered member is extended by at least a cylindrical bearing guiding it inside a corresponding bore in the body.

4. Cutting tool according to claim 3, wherein means are provided for the relative locking and centering of the body and of the said tapered member and are constituted by at least three radial lock screws which are screwed into the body and are adapted to rest on the said bearing, and by secant screws for locking the said lock screws into position, which secant screws are borne by the said body and accessible from the said supporting surface of the cutting plate.

5. Cutting tool according to claim 2, wherein the said tapered member comprises means controlling its rotation inside the body.

6. Cutting tool substantially as hereinbefore described with reference to, and as illustrated in, the accompanying drawings.