EP0014690A1

EP0014690A1 - Improvements in tool inserts and tools adopting such inserts

Info

Publication number: EP0014690A1
Application number: EP80830002A
Authority: EP
Inventors: Sergio Solari
Original assignee: STARK ITALIANA SpA
Current assignee: STARK ITALIANA SpA
Priority date: 1979-01-23
Filing date: 1980-01-12
Publication date: 1980-08-20
Also published as: IT7983311A0; ES487880A0; ES8101973A1; IT1127818B

Abstract

Tool inserts, advantageously but not restrictively inserts for rotating tools. The inserts being formed of a cutting bit (11), bit clamping and locking cap means (12) and securement means (14) advantageously screw means.

Projection means (25) provided in the tool head (29) are interferring partially with the cap means (12). Other projection means (23) provided in the cap means (12) are interferring partially with the securement means (14).

One projection (23) is cooperating with the means (12,14) with which it interfers, to generate a lateral clamping force due to the effect of the centrifugal force.

Description

in the name of STARK ITALIANA S.p.A. of Trivignano Udinese (UD) filed on under n°
The object of the present invention is improvements in tool inserts and tools adopting such inserts.
To be more specific, the present invention relates to im- . provements in tool inserts and in the seatings of such inserts, as well as to tools adopting such inserts and having such seat ings.
According to the invention, the improvements, advantageously but unnecessarily limited thereto, are particularly useful for rotating heads, for instance, of the-type used for wood working in which the insert is subjected not only to the normal working stresses but also to a significant centrifugal force due to the high speed at which the tool is rotated at least during the testing phase.
In this type of tools, in which the exerted stress due to . the centrifugal force is considerable, considerable problems . related to the securement of the inserts manifest themselves..
Diverse types of inserts have been studied, some work by expansion, others by lateral compression, others by the action of one or more screws, but all have drawbacks that limit their use which leave the problem of safety unsolved.
Besides, these drawbacks lead to difficulties in the replace ment of the tool bits (i.e. the parts of the insert that physi cally perform the cutting in tools), to an unstable securement, and to the risk of breakage of the securing element prevalently formed of a screw and the subsequent detachment of the insert.
At nearly ten to eleven thousand revolutions, or even less, such drawbacks cause the single insert element to behave as . potential projectiles ready to fly away.
The present invention attempts to provide an insert which . is safe for the operator whatever happens to the securement . means or the tools; in addition to this, the invention aims at improving the efficiency of the insert and at the same time to simplify all the operation of substituting the worn out tool . bits.
According to the invention, there are provided at least two safety provisions; one is associated with the clamping cap plate, for positioning and locking of the tool bits, the other . associated with the clamping and locking means of said cap . plate to the body of the tool head, such safety provisions can . be materialized singularly or togetherly on an insert.
According to the invention, even if they break, such clamp, ing and locking means of the cap plate to the tool head (means which are normally formed of a screw) whether due to the dynamic stresses or fatigue, or because a too high locking force has . been applied, or for other reasons (for example manufacturing defects) there is no danger of the cap plate or the bit or parts of the clamping and locking means coming off.
According to a preferential formulation an insert or bit is kept in position in the special seating in the tool head by a. wedge which includes an auxiliary element that penetrates a special seating provided in the said insert or bit.
This wedge, positioned in an inverted way, is kept in position by a cap plate having a cross section which is at least. partially an inverted trapeziodal; such cap plate having one . inclined side cooperating with the special seating provided in the tool head and placed opposite to the housing and pos itioning seat of the bit..
According to the invention, the seat provided in the tool head and cooperating with the inclined side of the cap has . above the cap itself a projection that is at least partially . covering the said cap.
Such a projection having advantageously an inclined plane,. . which can cooperate with a suitable inclined plane provided in . the cap in such a way that the centrifugal force exerted on . the cap is transformed into a self-locking force of the group formed of said cap-wedge-bit.
According to the invention, the said cap is normally locked in the special seat provided in the tool, by screw means ad-. vantageously but not necessarily having a cylindrical head with a counter-sunk hexagon.
The upper seat of said screw, provided in the cap, also have at the top some covering means extending at least partially . above said screw means in such a way that also the upper body. of the screw means themselves can not come out of its seat . with the removal of said covering means.
According to the invention, it is possible to obtain tools. of any width with said improved inserts..
In the case of wide tools, it will be sufficient that said. inserts are positioned in spaced rows, one row being at least- partially covering the uncovered part of the inserts of the previous row.
To simplify the assembly and disassembly in these cases it- is sufficient to provide on the side of one or more inserts a. shallow recess which is sufficiently deep and wide to-contain. the insert itself.
The invention can thus be summed up by improvements in tool inserts, advantageously but not restrictively rotating tool inserts, such inserts being formed of a cutting bit, at least. cap means for clamping and locking the bit and anchorage means, advantageously screw means, there being provided in the tool head a special counter-sunk seating placed superficially axial to at least part of the tool, characterised by the fact of con sisting of one or more of the following innovations:

- projection means provided in the tool head and interferring. at least partially with said cap plate on its extraction in a substantially radial direction;
- projection means provided in the said cap plate interferring at least partially with the said anchorage means; at least . one of the said projections being advantageously cooperating with the means with which it interfers to generate a clamping force at least lateral due to the effect of the centrifugal. force.

We now look, with the aid of the attached tables supplied . by way of non-restrictive example, into some of the preferential embodiments of the invention.
In the table, we have: .

Figs. 1, 2 and 4 represent three alternative preferential embodi ments of the invention;
Fig. 3 illustrates a two-securement solution of Fig. 2; .
Figs. 5 and 6 show one possible application on a wide tool; .
Fig. 7 shows one further alternative embodiment.

In the figures similar parts or parts with similar functions carry similar references..
In the drawings 10 is generically the insert composed in the example of the cutting bit or knife 11, the clamping and locking cap plate 12, the clamping wedge 13 and the anchorage means advantageously screw means 14; 11 is the cutting bit advantageously but not necessary of the throw-away type, said bit . have a bore 22 which cooperates with the pin 21 provided in the clamping wedge 13, the bit 11, the bore 22, the pin 21 and the clamping cap 13 are known in themselves; 12 is the clamping cap plate which forms the essence of the improvements..
The clamping and locking cap 13 has a seat 15, some secure. ment means 14 and the two inclined planes 16 and 17 which are. in themselves known.
The clamping and locking cap 12 also has the upper inclined plane 18, the chip discharge 19 and the seat 20 for the projec tion means 23 and provided for interferring with the securement screw means 14.
The means 18 are advantageously of the inclined plane type. but can be flat or filleted..
The means 23 can have a rectangular section (fig. 1) or round section (figs. 2, 4 and 7) and can be placed above the securement means 14 (figs. 1, 2 and 7) or cooperating with said means in an intermediate position (fig. 4).
The securement means 14 can have the part cooperating with. the projection means 23 straight or slightly filleted (fig. 1) or can have a substantial fillet or better still an inclined . plane 24 (figs. 2, 4 and 7).
The drawing also show that 25 is the projection substantially overlaying the cap plate 12 and having the plane 26 cooperating with the plane 18 of cap 12; 27 is the zone of possible breakage of the securement means 14; 28 is the part of the securement . means 14 which at the breakage of said means at 27 become free of any restraint; 29 is the tool head with the lower support . 30 and posterior support 31 for the bit 11, with the seat 32 . for the insert 10 and with the support 33 for the cap 12; 34 is the lateral recess provided in tool illustrated in figs. 5. and 6 which easily consents the lateral removal of the insert. 10; the recesses can be provided alternately as in fig. 4 or . in a spiral arrangement; 35 is the seat provided in the secure ment means 14 for the locking tool.
We now look into the functional aspect of the invention.
Given that the cap 12, the clamping wedge 13, the bit or knife 11 and the securement means are in themselves known, then tightening the securement means 14 by a suitable tool inserted in 35, the securement means 14, will cause said means to gener ate on the cap 12 a thrust towards the tool head.
This thrust is transmitted to the inclined plane 17 which, . by cooperating with the inclined plane 33, generates a thrust. in the direction of the bit 11.
Similarly, the inclined plane 16, acting against the clamping wedge 13, generates a thrust towards the bit and towards the . , . head of the tool.
This plurality of thrusts acting on the bit 11 causes said bit 11 to be pushed towards the lower support 30 and posterior support 31 which results in the positioning of said bit.
The presence of the engagement pin 21 cooperating with the. bore 22 ensures a higher safety..
The normal clamping problems relative to this known compli. cated arrangement are thus undoubtedly favourably solved.
But the proBems that could be caused by the breakage of the securement means 14 along 27 are not yet solved by the known . art.
According to the invention, it is envisaged that when the . element 28 of the securement means 14 is provided, it can not. in any case come out of its seat 15 due to the presence of the projection means 23.
. Said projection means can be of any type or any cross section.
Said projection means 23 can only interfer at the coming out of the element 28 so that this element can not leave its seat. ₁5, or can, in the presence of a centrifugal force which pushes the element 28, generate a thrust towards the tool head and a. lateral thrust (see fi^g. 2 and 4)..
Said projection means 23 as said before, can be placed above the securement means 14, or engage the same in an intermediate position as shown in fig. 4.
Since, however, the breakage of the securement means 14 frees also the cap 12 and consequently also the wedge 13 and the bit 11, the invention provides the means 25 engaging the cap 12 which prevents, due to the effect of the centrifugal force, such cap from leaving its seat 32.
Said projection means 25 advantageously include an inclined plane 26 which, when the cap 12 is displaced due to the cen- . trifugal force, by cooperating with the plane 18 generates a . thrust in the lateral direction and towards the tool head, a . thrust which simultaneously clamps also the wedge 13 and the . bit 11.
Some preferential solutions have been described herein, but other variations are possible without going beyond the ambit of the inventive concept.
It is thus possible to change the proportions and dimensions, r . it is possible to adopt improvements of one part to the other. and vice versa; it is possible ro remove or substitute parts,. ; etc.
These and other alternative embodiments are all possible for a person skilled in the art within the ambit of the inventive. idea.

Claims

1 - Improvements in tool inserts, advantageously but not restric tively inserts for rotating tools, said inserts (10) being . formed of a cutting bit (11), at least bit clamping and locking cap means (12) and securement means (14), advantageously screw- means, there being provided in the tool head a special counter-sunk seat (32) placed superficially in at least part of the tool (29), characterised by the fact of consisting of one or more of the following innovations:

- projection means (25) provided in the tool head (29) and in . terferring at least partially with the said cap means (12) on its extraction in a substantially radial direction; .

- projection means (23) provided in the said cap means (12) and interferring at least partially with the said securement means (14);

at least one of said projections being cooperating with the means with which it interfers, to generate an at least lateral. .clamping force due to the effect of the centrifugal force.

.2 - Improvements in tool inserts as in claim 1, characterised .by the fact that the projection means (25) provided in the tool .head (29) partially extend over the cap..

.3 - Improvements in tool inserts as in claim 1, characterised by the fact that the projection means (25) provided in the tool .head (29) extend into an intermediate longitudinal position with .respect to the cap.

4 - Improvements in tool inserts as in claim 1, characterised by the fact that the projection means (23) provided in the cap (12) extend at least partially into the housing seat (15) of . the securement means (14) and substantially on top thereof. 5 - Improvements in tool inserts as in claim 1, characterised by the fact that the projection means (23) provided in the cap. (12) extend at least partially into the housing seat (15) of the securement means (14) and substantially in an intermediate. .position with respect thereto.

.6 - Improvements in tool inserts as in claim 1 and any of the . .preceding claims, characterised by the fact that the projection means (23, 25) have a flat surface (26) cooperating with a simi .lar surface (18, 24) provided in the blocked means (12, 14), .at least one of said flat surfaces being advantageously inclined (18, 24).

.7 - Improvements in tool inserts as in claim 1 and any of the . .preceding claims up to and including claim 5, characterised by. the fact that the projection means (23, 25) have a curved sur . .face suitably cooperating with a surface (24) specially provided in the blocked means (12, 14).

.8 - Tools, advantageously but not restrictively rotating tools, characterised by the fact of adopting one or more improvements. .of the preceding claims.

.9 - Improvements in tool inserts and tools adopting inserts .thus improved in accordance with any of the preceding claims .as described and illustrated and for the conceived purposes.