EP1657036A1

EP1657036A1 - Milling tool

Info

Publication number: EP1657036A1
Application number: EP05110456A
Authority: EP
Inventors: Luca Solari
Original assignee: STARK SpA
Current assignee: STARK SPA
Priority date: 2004-11-10
Filing date: 2005-11-08
Publication date: 2006-05-17
Also published as: ITUD20040210A1

Abstract

Milling tool (10) comprising a rotary main body (11) provided with at least a radial seating (12), able to house a cutting insert (13) and a relative clamping device (14). The insert (13) comprises a front face (24) and a rear face (30), thrust by the clamping device (14) against a supporting surface (15) of the radial seating (12). A segment of the rear face (30) is converging towards the front face (24) so as to define a cross section that reduces in the direction going from the lower edge to the upper edge of the insert (13). The part of the radial seating (12) where the insert (13) is housed has, during use, a cross section mating with that of the insert (13).

Description

FIELD OF THE APPLICATION

The present invention concerns a milling tool used essentially but not only for working wood. To be more exact, the tool according to the invention is of the type comprising a rotary main body, on the periphery of which one or more cutting inserts are mounted.

BACKGROUND OF THE INVENTION

Milling tools are known, used in working wood in order to obtain different types of articles making grooves, notches or other, on a block of un-worked wood.
Known tools comprise a rotary main body, on the periphery of which a plurality of radial seatings are made, each of which houses inside it a relative cutting insert and a corresponding clamping element, or block, clamped under pressure in the seating.
When the cutting insert is assembled or replaced, the block can be made to slide on a bottom surface of the relative radial seating in order to thrust and stably clamp the cutting insert against a corresponding supporting surface or shoulder of the radial seating.
A solution is known, subject matter of the patent application UD2004A000163 in the name of the Applicant, which provides a conformation of the angles of the bottom of the seating and the lower profile of the block thanks to which, after every sharpening operation and during reassembly, the block automatically exerts on the cutting insert a thrust towards the outside too, in order to maintain the cutting radius at the value prior to the sharpening operation.
Known milling tools have the disadvantage, however, that in the case of cutting inserts with a relatively great weight, if very high speeds of rotation are used, there may be the risk of instability of grip due to the very high centrifugal forces which develop. This limits the potential use of the milling tool and the types of inserts that can be used.
One purpose of the present invention is to achieve a milling tool which can use high speeds and relatively heavy cutting inserts, guaranteeing in any case a sure grip of the cutting inserts.
The Applicant has devised, tested and embodied the present invention to overcome the shortcomings of the state of the art and to obtain these and other purposes and advantages.

SUMMARY OF THE INVENTION

The present invention is set forth and characterized in the main claim, while the dependent claims describe other characteristics of the invention or variants to the main inventive idea.
In accordance with the above purpose, a milling tool according to the present invention comprises a rotary main body provided with at least a radial seating, which is able to house a cutting insert and relative clamping means, for example a block, in order to clamp the insert against a supporting surface of the radial seating.
The insert comprises a front face, able to cooperate with the clamping means, and a rear face opposite the front face and able to be thrust on said supporting surface with a determinate pressure, which achieves the clamping of the insert on the main body.
According to a characteristic of the present invention, at least a segment of said rear face of the insert is converging towards said front face so as to define a cross section that reduces in the direction going from the lower edge to the upper edge of the insert, that is, from the center to the periphery of the main body when the insert is in its assembled position.
According to another characteristic of the present invention, the part of the radial seating where the insert is housed, that is, the part comprised between the clamping means and the supporting surface, includes during use a cross section mating with that of the cutting insert.
In this configuration, between the insert and the part of the radial seating where the insert is housed, a conical coupling is created which prevents the insert, due to the effect of the wedge-type clamping, from escaping from the corresponding radial seating due to the centrifugal force acting thereon. In this way the insert is guaranteed to remain inside the relative seating, substantially in any operating condition and with any type of insert used, especially in those cases where the weight of the insert is very great, or the speed of rotation of the milling tool is very high, or is subject to frequent variations.
In a preferential embodiment, the rear face of the cutting insert, disposed during use in contact with the supporting surface of the radial seating, comprises at least a first lower part and a second upper part, substantially aligned with respect to each other, and at least an intermediate part, comprised between the two.
In this embodiment, the first lower part and the second upper part define a reference plane, substantially parallel to that defined by the front face of the insert, the function of which is to ensure a precise positioning of the insert at the start of working.
The intermediate part is converging towards the front face in the direction going from the bottom to the top of the insert, and is disposed in contact with the supporting surface of the radial seating. The supporting surface is also inclined by an equal angle with respect to the reference plane defined by the two aligned parts of said rear face, so as to create a conical coupling which prevents the insert from escaping from the radial seating due to mechanical clamping.
The intermediate part is advantageously inclined by an angle comprised between 2° and 10°, with respect to the reference plane defined by the first lower part and the second upper part.

BRIEF DESCRIPTION OF THE DRAWINGS

These and other characteristics of the present invention will become apparent from the following description of a preferential form of embodiment, given as a non-restrictive example with reference to the attached drawings wherein:

fig. 1 is a partial front view of a milling tool according to the present invention;
fig. 2 is a partial front view of a cutting insert used in the milling tool in fig. 1;
fig. 3 is a front view of a radial seating of the milling tool in fig. 1;
fig. 4 is a partial front view of the milling tool in fig. 1 in a first operating condition.

DETAILED DESCRIPTION OF A PREFERENTIAL FORM OF EMBODIMENT

With reference to fig. 1, a milling tool 10 according to the present invention is used to make grooves or other types of notches on blocks of un-worked or semi-worked wood, so as to obtain desired profiles on the visible surfaces of said blocks.
The milling tool 10 comprises a main body 11, in this case cylindrical, rotating around an axis X and on the periphery of which a plurality of radial seatings 12 are made, each of which houses a cutting insert 13 and a corresponding clamping device 14.
Each radial seating 12 (figs. 1 and 3) comprises a supporting shoulder 15 for the insert 13 and a bottom surface 16, cooperating with the clamping device 14.
The insert 13 (figs. 1 and 2) comprises an outer surface 27, a lower surface 26 opposite and parallel the outer surface 27, a rear face 30 which during use is thrust under pressure against the shoulder 15, and a front face 24 opposite the rear face 30.
To be more exact, the bottom surface 16 (figs. 1 and 3) of the radial seating 12 comprises, in this case, a first segment 16a, inclined towards the inside of the radial seating 12 by an angle β, comprised between 80° and 90° with respect to a cutting radius R, passing through the front edge of the outer surface 27, and a second segment 16b, adjacent and offset with respect to the first segment 16a and inclined by an angle α, with respect to the latter, towards the outside of the radial seating 12.
The shoulder 15 (figs. 1 and 3), in this case, is made adjacent and perpendicular to the second segment 16b, so as to be inclined towards the inside of the radial seating 12.
The clamping device 14 (fig. 1) comprises a shaped block 17, which cooperates with the insert 13 to keep it pressed, with great pressure, against the shoulder 15, and a screw 20, accessible from outside, which thrusts the block 17 against the insert 13. To be more exact, the screw 20 can be screwed in a relative through hole 21, made in correspondence with the radial seating 12 on the opposite side with respect to the shoulder 15.
The block 17 comprises a lower surface 22, sliding on the first segment 16a of the bottom surface 16 of the radial seating 12, a contact surface 23, which contacts the front face 24 of the insert 13, and a sliding surface 25, on which the lower surface 26 of the insert 13 is able to slide.
By screwing the screw 20 into the corresponding hole 20 the insert 13 is clamped against the shoulder 15.
In the embodiment described so far, thanks to the angled configuration of the surfaces of the radial seating 12, the block 17 and the insert 13, after the insert 13 has been sharpened by edging the front face 24 (fig. 4), the progressive screwing of the screw 20 determines a corresponding thrust of the insert 13 towards the outside of the radial seating 12, so as to keep constant the cutting radius R of the milling tool 10 at the same value as prior to sharpening.
The rear face 30 (fig. 2) comprises in this case a first lower part 31, a second upper part 32 and an intermediate part 33, comprised between the two parts 31 and 32.
The first lower part 31 and the second upper part 32 are aligned with each other along a reference plane B, substantially parallel to a plane containing the front face 24.
The intermediate part 33 originates on the upper edge of the first lower part 31, ends in proximity with the lower edge of the second upper part 32 and is inclined towards the front face 24, in the direction of the periphery of the main body 11, that is, from the bottom towards the top of the insert 13, by an angle ϕ with respect to the reference plane B (fig. 2). In this way, in correspondence with the intermediate part 33, the cross section of the insert 13 is reduced in a radial direction, that is, the section of the insert 13 progressively decreases as it goes towards the outside of the main body 11.
The shoulder 15 has an inclination with respect to an orthogonal line originating from the second segment 16b of the bottom surface 16 of the radial seating 12, by an equal angle ϕ. In this case the angle ϕ is equal to about 5°.
The contact between the intermediate part 33 and the shoulder 15, and between the contact surface 23 of the block 17 and the front face 24 of the insert 13, determines a conical coupling between the insert 13 and the part of the radial seating 12 comprised between the shoulder 15 and said contact surface 23 where, during use, the insert 13 is housed. This prevents the insert 13, due to the effect of a wedge-type mechanical clamping, from escaping from its radial seating 12 due to centrifugal force, irrespective of its weight or the number of revolutions with which the main body 11 is made to rotate. This embodiment therefore allows to increase, in safety, the speed of rotation usable with inserts even of great weight.
The comparison between fig. 1 and fig. 4 shows how the insert 13 is clamped on the corresponding radial seating 12 due to the effect of the conical coupling even when the thickness of the insert 13, following repeated sharpening operations, is very much reduced with respect to the initial thickness.
It is clear that modifications and/or additions of parts may be made to the milling tool 10 as described heretofore, without departing from the field and scope of the present invention.
It is also clear that, although the present invention has been described with reference to some specific examples, a person of skill in the art shall certainly be able to achieve many other equivalent forms of milling tool, having the characteristics as set forth in the claims and hence all coming within the field of protection defined thereby.

Claims

Milling tool comprising a rotary main body (11) provided with at least a radial seating (12), able to house a cutting insert (13) and relative clamping means (14) of said insert (13), said insert (13) comprising a front face (24), cooperating with said clamping means (14), and a rear face (30), opposite said front face (24) and able to be thrust against a supporting surface (15) of said radial seating (12) by said clamping means (14), characterized in that at least a segment of said rear face (30) of said insert (13) is converging towards said front face (24) so as to define a cross section that reduces in the direction going from the lower edge to the upper edge of said insert (13), and in that the part of said radial seating (12) where said insert (13) is housed has, during use, a cross section mating with that of said insert (13).
Milling tool as in claim 1, characterized in that said rear face (30) comprises at least a first lower part (31) and a second upper part (32), substantially aligned with respect to each other so as to define a reference plane (B) and at least an intermediate part (33), comprised between said first lower part (31) and said second upper part (32), converging towards said front face (24) and is able, during use, to contact said supporting surface (15) of said radial seating (12).
Milling tool as in claim 2, characterized in that said reference plane (B) is substantially parallel to the plane containing said front face (24).
Milling tool as in claim 2 or 3, characterized in that said intermediate part (33) is inclined with respect to said reference plane (B) by an angle (ϕ).
Milling tool as in claim 4, characterized in that said angle (ϕ) is comprised between about 2° and about 10°.
Milling tool as in claim 4 or 5, characterized in that said supporting surface (15) is inclined by said angle (ϕ) with respect to said reference plane (B).