Rotary tool for high speed machining of wood, plastics or light metals

Abstract

 The invention concerns means to clamp inserts in rotating tools, and advantageously in rotating tools employed in processing of wood, plastics or light metals, whereby said rotating tools travel at a very high speed and the inserts (23) can be re-used and readily replaced, said clamping means being characterized by the fact that in the tool holder (10) there is envisaged a plurality of housing spaces (11) which have a shape substantially like a truncated cone and which widen towards the middle of said tool holder (10), whereby a seating (14) for a tool is positioned at the side of said housing space (11) and a clamping body (17) is located in said housing space (11) and cooperates with at least one resisting block (18), and whereby at least said resisting block (18) cooperates with a regulating screw (19) able to exert on said resisting block (18) and on said clamping body (17) a lateral thrust such as will constrain said resisting block (18) against the opposing wall (12) of said housing space (11) and will constrain said clamping body (17) against said insert (23) and substantially towards the middle of said tool holder (10).

Description

[0001] This invention concerns means to clamp inserts in rotat- . ing tools.

[0002] To be more exact, this invention concerns means to clamp. inserts in rotating tools which are employed advantageously. for the processing of wood or plastics, or, in any case, in tools which rotate at high speed.

[0003] It is known that the clamping of inserts is a grave problem for the safety of machine operatives and for the accurate alignment and balancing of the tools themselves.

[0004] Lastly, the clamping of the tools is reflected in the quality of the finished product.

[0005] At the speeds at which the tools rotate nowadays, their clamping has become an important feature in that the inserts have been standardised and have reached an optimal level of performance.

[0006] The problems to be overcome in up-to-date clamping means. are manifold and indeed it is necessary to be able to obtain clamping means which are strong and stable enough to withstand all kinds of vibration.

[0007] It is necessary to provide clamping means which do not need to be removed during assembly and dismantling.

[0008] Clumping means have to be provided which align and secure the insert automatically.

[0009] It is necessary to provide clamping means which, owing to their very nature, constrain the insert with an action that- opposes centrifugal force.

[0010] It is also necessary to provide clamping means which do not leave their housing even if they have been badly secured.

[0011] All these purposes together with further purposes and advantages are pursued by the invention according to this description.

[0012] According to the invention a housing space is envisaged which has the shape substantially of a truncated cone and which widens towards the middle of the tool holder.

[0013] At the side of the housing space is envisaged a suitable seating space for the tool, and said seating is dimensioned and positioned perfectly in relation to the middler of the tool itself so that, when said seating supports the tool or- insert, said tool or insert is located perfectly in relation to the middle of the tool holder and therefore in relation to the plurality of other tools or inserts.

[0014] . Into said housing space are introduced at least two bodies which cooperate with each other by means of screw means, whereby the reciprocal action carried out by the screw means is such as to thrust one body towards an opposing wall, whereas- the other body, the so-called clamping body, is thrust towards the insert.

[0015] . At the same time the insert is pushed by said latter body with a thrust substantially towards the middle of the tool - holder.

[0016] According to a first formulation of the invention the clar- mping body has two clamping surfaces that cooperate with resisting blocks on which a regulating screw having a righthand thread and a lefthand thread acts.

[0017] By turning the screw said resisting blocks can be brought nearer to or farther from each other.

[0018] The action of said resisting blocks on the opposing sur- . faces causes a sideways thrust towards the middle of the tool holder. This is so because, by pressing against the opposing wall, said blocks constrain the clamping body to move side- . ways towards the insert and substantially towards the middle of the tool holder.

[0019] According to this preferential embodiment the regulating screw comprises in an intermediate position a ring which provides lengthwise anchorage and which can cooperate with an anchorage hollow that may possibly be included in the clamping body.

[0020] Substitute means can also be visualised.

[0021] Said anchorage ring can cooperate with a safety pin which holds the regulating screw onto the clamping body and which can exert at the same time on the clamping body an outwards thrust that constrains said clamping body to be embedded in the housing space.

[0022] . According to another variant the anchorage ring has an intermediate hollow within which the safety pin is made to pass.

[0023] According to a further variant the opposing surfaces are- not linear but have a substantially rounded development so - as to reduce to a minimum the necessity for accurate mating This makes it possible to maintain at the same time a thrust strong enough to obtain an almost irreversible clamping condition when the forces in question are taken into account.

[0024] Moreover, the area of contact between the resisting block and the opposing wall may possibly be suitably shaped. According to a second further embodiment the resisting block cooperates with a screw located in an almost radial position and acting on both the recisting block and the clamping body at the same time.

[0025] Thus, by acting on said screw the two elements are moved. towards each other or one of them is moved in a direction opposite to the other, thus constraining the clamping body to thrust the insert downwards and sideways and keeping it in the right position in relation to the seating of the tool.

[0026] . According to yet another embodiment the resisting block . comprises a slit such that the walls of the block itself are made elastic.

[0027] . when a screw is caused to act on said walls, a union substantially with the shape of a truncated cone between the resisting block and the clamping body forces the clamping body itself to move sideways and downwards and thus constrains the insert to be secured perfectly within the seating of the tool.

[0028] . The invention is therefore embodied in means to clamp inserts in rotating tools, and advantageously in rotating tools employed in the processing of wood, plastics or light metals, whereby said rotating tools travel at a very high speed and- the inserts can be re-used and readily replaced, said clamping means being characterised by the fact that in the tool . holder there is envisaged a plurality of housing spaces which have the shape substantially of a truncated cone and which - widen towards the middle of the tool holder, whereby a seating for a tool is positioned at the side of said housing space and a clamping body is located in said housing space and cooperates with at least one resisting block, and whereby at least the resisting block cooperates with a regulating screw able to exert on said resisting block and on said clamping - body a lateral thrust such as will constrain said resisting- block against the opposing wall of said housing space and will constrain said clamping body against the insert and substantially towards the middle of the tool holder.

[0029] Let us now see some preferential lay-outs of the invent- . ion with the help of the attached table, which gives some non-restrictive examples.

[0030] The table contains the following:-

Fig.I gives a vertical section of a possible embodiment of. the invention;

Fig.2 shows the embodiment of Fig.I according to a lengthwise section;

Fig.3 shows a variant evolved from Fig.I;

Fig.4 shows an evolutive variant of the regulating screw;

Fig.5 shows the embodiment of another variant;

Fig.6 shows the embodiment of another variant in relation . to Fig.5;

Figs.7 & 8 show a section and a side view of another variant. With reference to the figures, the tool holder 10 comprises a housing space II with an opposing wall 12 and a supporting wall 13; a lateral seating 14 for a tool is provided in the supporting wall 13.

[0031] Said seating I4 for a tool includes a supporting corner 15 and a wall 16 supporting an insert.

[0032] The conformation of the housing II substantially like a truncated cone has the effect that, as the wall I6 support- - ing the insert 23 is substantially parallel to a plane passing through the axis of the toolrholder I0, the opposing

[0033] wall I2 will cut said plane at a position a great deal above the middle of the tool holder I0.

[0034] . The wall 16 supporting the insert and the supporting corner of said seating 14 for a tool are positioned perfectly in relation to the centre of rotation of the tool holder 10. A clamping body 17 is introduced within the housing II and., in the example of Fig.I, comprises a lengthwise hollow 32 in which are located two resisting blocks 18-118 cooperating with a regulating screw 19 having a righthand and a lefthand thread. Said regulating screw 19 includes a ring 20 for lengthwise anchorage, and said ring 20 cooperates with a hollow 21 for- lengthwise anchorage formed in the clamping body 17.

[0035] Opposing surfaces 22 are provided in the lengthwise hol-· low 32 of the clamping body 17 and cooperate with respective resisting surfaces 122 formed on the resisting blocks 18.

[0036] Thus, when the regulating screw 39 is turned, the resisting blocks 38 are, for instance, drawn towards each other and the respective resisting surfaces 122 press on the opposing surfaces 22 of the clamping body 17.

[0037] This pressure constrains the resisting blocks 18 to move. sideways until they rest against the opposing wall 12.

[0038] As soon as said resisting blocks 18 rest against the opposing wall 12, they constrain the clamping body 17 to move. in its turn.

[0039] . The position of the opposing wall 12 conditions the char- .acteristics of the movement of the clamping body 17.

[0040] When the clamping body 17 moves, it acts on the insert 23 .or tool having a re-usable and replaceable tip. Said tool 23 comprises one or more holes 24 which cooper- .ate with appropriate pins 25 solidly fixed to the clamping body 17.

[0041] Owing to the action of the resisting blocks 18 against the clamping body 17 the pin 25 rests against the bottom of the- hole 24 and engages the insert 23.

[0042] This action constrains the insert 23 to rest perfectly .against the wall 16 and at the same time against the corner- .15 and to be positioned perfectly in relation to the middle- .of the tool holder 10 and to the other tools.

[0043] The clamping body 17 is advantageously envisaged as comprising a protective outlet 26 which cooperates with the cut- .ting edge of the insert 23 lying against the supporting corner 15.

[0044] So as to prevent the regulating screw 19, and therefore . the resisting blocks 18, from becoming detached possibly from the clamping body 17 during movement, it is possible to visualise a safety pin 27 which engages the clamping body 17 and the regulating screw 19.

[0045] It is possible to obtain an auxiliary safety function with .said safety pin 27 if said safety pin protrudes from the low- .er side of the body 17 and cooperates with the bottom of the housing II.

[0046] In such a case, if the safety pin 27 is elastic enough and is made to work by bending against the bottom of the housing II, it will constrain the clamping body 17 with an outwards. .thrust.

[0047] This makes it possible to ensure a grip and security which could not be obtained otherwise in the case of imperfect clamping by the resisting blocks 18.

[0048] Said safety pin 27 can be single, as in Fig.I, or double, as in Fig.3, or can have other suitable shapes according to. the requirements of the design.

[0049] According to a variant the ring 20 providing lengthwise anchorage and comprised in the regulating screw 19 can have. an intermediate hollow 28 within which the safety pin 27 is. made to lodge; in this way the hollow 21 providing lengthwise anchorage is rendered substantially useless.

[0050] The embodiment now shown entails a movement substantially parallel to the axis of rotation of the tool holder 10.

[0051] With the invention, however, it is also possible to obtain clamping of the inserts 23 by making use of an action of the resisting blocks 218 in a substantially radial direction.

[0052] This too is due to the reciprocal disposition of the wall I2 and wall 13 in relation to the centre of rotation of the tool holder 10.

[0053] Indeed, as can be seen in Figs.5 & 6, a clamping action . .can be obtained which is in principle substantially the same .as that of Fig.I but which is substantially different as an. .embodiment to be applied.

[0054] According to said variants the resisting block 218 is thrust towards the opposing wall 12 by screw means II9, which. also have a righthand and a lefthand thread and which engage the resisting block 218 and the clamping body II7 at one and the same time.

[0055] In this way the clamping body II7 is thrust not only towards the supporting wall 13 but also towards the insert 23. and constrains said insert 23 to rest against the supporting corner 15.

[0056] The difference between the lay-outs of Figs.5 & 6 lies substantially in greater security of the invention in the example of Fig.6.

[0057] In fact, the twofold inclination permits safer and more . longlasting anchorage in the long term even when there are - vibrations.

[0058] Indeed, the reciprocal sliding wall 31 of Fig.5 is sub- - stantially parallel to the wall 13, whereas there is an angle between said walls in Fig.6.

[0059] In the examples of Figs.7 & 8 the resisting block 318 comprises a hollow which enables the two sides A & B of the block itself to bend in relation to each other, whereby the side B is able to lodge the head 30 of the screw 230, whereas the side A can lodge the threaded part 130 thereof.

[0060] When the screw 219 is turned, the two sides A & B of the- resisting block 218 tend to come nearer to each other.

[0061] This action is opposed by the presence of the body 217, which is thrust towards the insert 23, whereas the resisting block 318 is thrust towards the wall 12, the two oblique sides 131 acting as wedge means.

[0062] We have described herein some preferential embodiments, but variants are possible and it can be seen that some embod- inents are suitable for wide tools and others for narrow tools whereas others again are suitable for very narrow tools.

[0063] Thus, the proportions, sizes and parts can be varied and. various parts can be combined together according to the in-. ventions.

[0064] It is possible to visualise that the opposing surfaces 22-I22 are rounded or crovm-shaped; it can be envisaged that the .sliding surfaces 31 between the body 218 and body 217 may .possibly have a special shape, and so forth.

[0065] These and other variants are all possible for a technician in this field.

Claims

I. Means to clamp inserts in rotating tools, and advant, ageously in rotating tools employed in the processing of . wood, plastics or light metals, whereby said rotating tools travel at a very high speed and the inserts (23) can be re-used and readily replaced, said clamping means being char-. acterised by the fact that in the tool holder (10) there is envisaged a plurality of housing spaces (II) which have the shape substantially of a truncated cone and which widen towards the middle of the tool holder (10), whereby a seating (14) for a tool is positioned at the side of said housing space (II) and a clamping body (17) is located in said housing (II) and cooperates with at least one resisting block-(18), and whereby at least the resisting block (I8) cooperates with a regulating screw (19) able to exert on said resisting block (I8) and on said clamping body (17) a lateral thrust such as will constrain said resisting block (18) against the opposing wall (12) of said housing (II) and will. constrain said clamping body (17) against said insert (23) . and substantially towards the middle of said tool holder(I0).

2. Means to clamp inserts in rotating tools as in Claim. I, characterised by the fact that the conformation of the housing spaces (II) substantially like a truncated cone has the effect that, as the wall (16) supporting the insert (23) is positioned substantially parallel to a plane passing through the axis of the tool holder (10), the opposing wall (12) cuts said plane in a position a great deal above the middle of the tool holder (10).

3. Means to clamp inserts in rotating tools as in Claim. I or 2, characterised by the fact that the clamping body (1-7) comprises lengthwise hollow means (32) substantially normal to the opposing wall (12) and having two opposing surfaces (22) disposed as counterparts of each other.

4. Leans to clam inserts in rotating tools as in Claim. I or in one or the other of the Claims thereafter, charact- ised by the fact that two resisting blocks (18) cooperate . in the lengthwise hollow (32) comprised in the clamping body (17) with opposing surfaces (122) and with a regulating screw (19) having a righthand and a lefthand thread...

5. Means to clamp inserts in rotating tools as in Claim. I or in one or another of the Claims thereafter, characterised by the fact that the clamping body (17) cooperates with safety pin means (27), whereby said means (27) anchor the . regulating screw (19) and advantageously protrude elastically into the lower part of said clamping body (17) so as to cooperate with the bottom of the housing space (II).

6. Means to clamp inserts in rotating tools as in Claim. I and in one or another of the Claims thereafter, characterised by the fact that the safety pin means (27) cooperate . with anchorage ring means (20) located on the regulating screw means (19).

7. Means to clamp inserts in rotating tools as in Claim. I and in one or another of the Claims thereafter, characterised by the fact that the regulating screw means (19) cooperate at their side with hollow means providing lengthwise anchorage (21) comprised in the clamping body (I7).

8. Means to clamp inserts in rotating tools as in Claim I and in one or another of the Claims thereafter, characterised by the fact that the resisting block means (218) are . one in number and cooperate in a lateral and higher position with clamping body means (117) by means of regulating screw means (19) and with sliding and facing sides (31)(Figs.5 &. 6).

9. Means to clamp inserts in rotating tools as in Claim. I and in one or another of the Claims thereafter, characterised by the fact that the resisting block means (318) com- . prise two sides (A ― B) having a hollow between them (29) . and bound together by screw means (219) and having oblique . sides (I3I) cooperating wedge-wise with the clamping body .(217)(Figs-7 & 8).

Drawing