WO2018235120A2

WO2018235120A2 - Clamping system for a tool in a tool holder

Info

Publication number: WO2018235120A2
Application number: PCT/IT2018/050112
Authority: WO
Inventors: Cornelio Molteni
Original assignee: Kovall Tools S.R.L.
Priority date: 2017-06-22
Filing date: 2018-06-20
Publication date: 2018-12-27
Also published as: WO2018235120A3; IT201700070039A1

Abstract

Cold-clamping and disassembling system of a tool in and from a spindle consisting of a locking and unlocking device, a bushing serving as a bearing and spindle diameter adapter for its insertion into the locking device, a torque wrench, a high-performance spindle, said system being capable of achieving the performance of the hot shrink-fit.

Description

CLAMPING SYSTEM FOR A TOOL IN A TOOL HOLDER

The present invention relates to a high-performance clamping and sealing system for a tool in a spindle which in turn comprises a locking device, a bushing serving as a bearing and reducer, a torque wrench, and a high-performance spindle. Each of these elements which have innovative characteristics with respect to the prior art, as well as the combined use of such elements produces an unexpected result in terms of tightness and clamping effectiveness and precision.

In the hot shrink-fit systems, the tool is locked in a high precision and rigidity spindle. Such shrink-fit system is used for tools that work at high speeds and for machining operations where the manoeuvring spaces are reduced, and the depths would be critical using traditional locking systems. With this technique the tool holder is heated to reach the suitable temperature (approximately 300/400 °C) to expand and to accommodate the selected tool shank. The subsequent cooling (at room temperature or with dedicated cooling systems) restricts the tool holder around the tool and therefore allows a very precise and high grip clamping thanks to the natural radial force developed during the process. The greater the temperature difference between the spindle and the tool, the faster the assembly and disassembly time of the tool from the spindle with undeniable advantages. The thermal shrink-fit is characterized by an excellent concentricity of less than 3 microns, a very high level of precision and performance, high clamping resistance and strength with high rigidity, perfect balancing, quick insertion and extraction of the tool, longer tool life.

As opposed to the aforementioned advantages of the hot shrink-fit, the disadvantages associated with cold shrink-fit derive from the high costs of the related equipment for heating the spindle, the electric heating costs to make the spindle reach the desired temperature, as well as problems of practicality and encumbrance deriving from the equipment needed for heating the spindle.

A further disadvantage of the hot shrink-fit derives from the fact that if the equipment overheats the spindle too much, it may happen that the tool drops too much inside the spindle, causing loss of time and a new heating cycle to restore correct positioning of the tool.

The object of the present invention is therefore a clamping system for a tool in l a spindle consisting of a locking device, a bushing serving as a bearing and reducer, a torque wrench, a high-performance spindle.

An object of the present invention is to obtain a clamping system for a tool from a cold tool holder, but which achieves the same performances typical of the heat shrink-fit process and therefore high grip and precision performances.

Another object of the present invention is to obtain a clamping system in which there is no possibility that the tool lowers too much inside the spindle during the clamping phase, thus resulting in the tool always being in an optimum position within the spindle during clamping.

A further advantage derives from the fact that the entire system is of limited costs, does not provide for additional equipment and is easy to manoeuvre and without particular efforts by the operator.

In particular, an advantage achieved by the spindle object of the invention is that it offers excellent clamping accuracy and excellent rigidity of the assembly.

An advantage imparted by the cylindrical bushing is avoiding possible dents to be formed on the spindle itself, caused by the clamping system object of the invention, said dents which can create dangerous vibrations during the operation of the spindle due to its rotation at high speed. A further advantage imparted by the bushing is serving as a reducer/adapter for the diameters of spindles that are too small compared to the diameter of the locking device.

In particular, an advantage achieved by the locking device is unlocking the locking support of the spindle with a simple pressure of the hand by the operator.

Moreover, an advantage achieved by the torque wrench object of the invention is being able to convey the necessary clamping force of the tool in the spindle with easy manoeuvring and without excessive effort by the operator. Another advantage achieved by the torque wrench object of the invention is due to the fact that the clamping force exerted by the ring of the wrench is radially distributed, such that its external circumference is uniformly deformed in order to avoid dangerous vibrations during the operation of the spindle due to its high-speed rotation.

The system object of the invention as a whole has reduced production costs and therefore supply costs, both for the types of machining operation and the materials required.

These and further objects will be carried out by the clamping system according to the present invention, which will be equipped with a locking device equipped with locking rollers, a bushing serving as a bearing and reducer, a high-performance spindle equipped with a thread on the inclined body, a torque wrench equipped with clamping rollers, as described in the present invention below.

The object of the present invention will be illustrated in detail by the attached figures and description thereof in which only some of the possible innovative embodiments are described, wherein:

Fig. 1 is a section view of the cam support 10 of the locking device 1 of the system according to the invention;

Fig. 2 is a top view of the guide ring 11 of the locking device 1 of the system according to the invention;

Fig. 3 is a section view of the guide ring 11 of the locking device 1 of the system according to the invention;

Fig. 4 is a section view of the main body 30 of the spindle 3 of the system according to the invention;

Fig. 5 is a section view of the ferrule 32 of the spindle 3 of the system according to the invention is shown in section;

Fig. 6 is a top view of the cam profile 400 of the torque wrench 4 of the system according to the invention;

Fig. 7 is a section view of the guide ring 41 of the torque wrench 4 of the system according to the invention;

Fig. 8 is a top view of the guide ring 41 of the torque wrench 4 of the system according to the invention;

Fig. 9 is a top section view of a detail of the torque wrench 4 of the system according to the invention;

Fig. 10 is a section view of the cylindrical body 20 of the cylindrical bushing 2 of the system according to the invention;

Fig. 11 is a top view of the cylindrical body 20 of the cylindrical bushing 2 of the system according to the invention;

Fig. 12 is a section view of the assembly of the system according to the invention;

Fig. 13 is a section view of a further embodiment of the torque wrench with the portion of the telescopic handle being uncoupled; Fig. 14 is a section view of the further embodiment of the torque wrench with the portion of the telescopic handle being coupled.

In particular, with reference to Figures 1 , 2, 3 and 12, the locking device 1 is shown, adapted for retaining the main body 30 of a spindle 3 in a fixed position, comprising a cam support 10 essentially consisting of a steel element in section of an omega or C shape, which provides for one or more fixing portions 102 by known fixing means such as screws, bolts or other of the cam support 10 to the workbench. The cam support 10 also provides for a shaped hole 101 with a cam profile 100 (for example a daisy-like profile) inside which and against which the rotating elements 12 housed in the intermediate portion 111 of the guide ring 11 are able to work. In particular, the rotating elements 12 consist of cylindrical-section rollers, housed and free to rotate about their axis, in suitable seats equipped with windows 113 formed along the circumference of the guide ring 11 ; it is specified that the rotating elements rest on a circular crown base 114. More particularly, said rotating elements 12 rotate from a rest position in which each rotating element 12 is housed in a depression formed between two successive cams, to a working position where each rotating element 12 is positioned at each cam of the cam profile 100, thereby partially projecting from the respective window 113 towards the inside of the shaped hole 101 and thus coming into contact and pressing against the main body 30 of the spindle 3 to be clamped, holding it in a fixed position. The said windows 113 are configured both to avoid the complete exit of the rotating elements 12 and to allow the partial exit of the rotating elements 12 when they come into contact with the cams of the cam profile 100.

The guide ring 11 provides for an upper portion 110 which comprises a circular seat 16 inside of which a plurality of balls 13 are free to rotate, said balls 13 rotate when the guide ring 11 is rotated clockwise or anticlockwise by the operator, said balls 13 being in contact on one side with the upper portion 110, through the circular seat 16, and on the other side with the upper surface of the cam support 10, said balls 13 allowing rotation between the guide ring 11 and cam support 10.

The intermediate portion 111 of the guide ring 11 , as previously said, provides for a plurality of seats equipped with windows 113, said circumferential seats being adapted for housing the rotating elements 12, therefore the intermediate portion 111 , the rotating elements 12, the windows 113 can have a height corresponding with the thickness of the cam support 10, said seats equipped with windows 113 being arranged equidistantly along the inner circumference of the guide ring 11. The lower portion 112 of the guide ring 11 is instead configured in such a way as to provide a constraint for the extraction of the guide ring 11 from the cam support 10, said constraint for extraction consisting for example of the combined effect of a stop ring 15, housed in a stop ring seat 17 made on the lower portion 112, said stop ring 15 which in turn blocks a seal ring 14 which in turn holds in place and therefore inside the respective windows 113 the rotating elements 12. It is specified that both the stop ring 15 and the seal ring 14 can rotate about their own axis. The use of a stop ring 15 and a seal ring 14, allow the correct operation of the locking device 1 of the system object of the invention.

Inside the shaped hole with cam profile 100 of the cam support 10 is inserted the main body 30 of the spindle 3, inside of which must be inserted the shank of the tool to be locked. Therefore, by slightly turning the main body 30 of the spindle 3 clockwise or anticlockwise, it is possible to lock/unlock the main body 30 in a position, by means of the pressure exerted on the main body 30 by the rotating elements 12 when they come into contact with the cams of the cam profile 100 of the cam support 10.

However, in order to avoid any dents or damage to the spindle 3 when clamped or disassembled inside the shaped hole 101 with a cam profile 100, or in any case in order to serve as a diameter reducer/adapter in the event of clamping or releasing the spindle 3 from the shaped hole with cam profile 100, a cylindrical bushing 2 has been devised which serves as a bearing and reducer and which is inserted directly inside the shaped hole 101 with a cam profile 100, and therein is inserted the main body 30 of the spindle 3.

The cylindrical bushing 2 (see Figures 10 and 11 ) provides for a cylindrical body 20 equipped with longitudinal slots 21 which allow radial pliability when subjected to the thrust exerted by the rotating elements 12 due to the cams of the cam profile 100. The cylindrical bushing 2 also provides for a head crown 22 free to rotate about its axis above the cylindrical body 20 and interlocked thereto against the longitudinal extraction in the direction of its axis. The head crown 22 is in fact in contact with the upper portion 110 of the guide ring 11 , while the cylindrical body 20 is in contact externally with the rotating elements 12 and internally with the main body 30 of the spindle 3.

The spindle 3 (see Figures 4 and 5) provides for, as previously said, a main body 30 which ends with a plurality of jaws 31 which are pushed to approach radially with each other and then to clamp the shank of the tool to be clamped, through a ferrule 32. The peculiarity of the spindle 3 object of the invention consists in the fact that the jaws 31 do not follow the cylindrical profile of the main body 30, but they follow a conical profile, and provide for, on their external surface, a conical thread capable of coupling with a corresponding counter-conical thread provided for inside the ferrule 32, preferably also frustoconical. The particular frustoconical structure of the jaws 31 and of the ferrule 32 causes the insertion of the tool shank to be facilitated, and that the ferrule 32, after a partial unscrewing, can be extracted/withdrawn from the spindle 3.

Moreover, the main body 30 comprises an upper centring portion 33a and a lower centring portion 34a configured to couple with a corresponding upper centring portion 33b and a lower centring portion 34b, respectively, provided for inside the ferrule 32, to optimize centring between the ferrule 32 and the main body under clamping condition. Furthermore, the main body 30 comprises a threaded portion 35b adapted for screwing to a corresponding threaded portion 35b provided for inside the ferrule 32.

In a further embodiment, the spindle 3 is a monoblock body and does not provide for jaws in which to insert the tool shank, however in order to make the part of the spindle 3 in which the tool shank is inserted more elastic and deformable, such portion is scored and engraved by means of a spiral profile, which besides facilitating the deformability, facilitates the closing stress, reducing the force required to clamp the spindle 3.

The torque wrench 4 is shown in Figures 6 to 9 and it is substantially structured as the locking device 1 . This provides for a handle 48 equipped with a grip for the safe clasp of the operator, as well as a circular wrench 40 located at the end of the handle 48, inside of which is inserted the ferrule 32 of the spindle 3 to be clamped or disassembled from the main body 30 of the spindle 3.

The circular wrench 40 provides for a shaped hole with a cam profile 400 (for example, a daisy-like profile) inside of which and against which the rotating elements 42 housed in the intermediate portion 411 of the guide ring 41 are capable of working. In particular, the rotating elements 42 consist of cylindrical-section rollers housed and free to rotate about their axis, in appropriate seats equipped with windows 413 formed along the outer circumference of the guide ring 41 , said seats equipped with windows 413 being arranged equidistantly along the inner circumference of the guide ring 41 ; it is specified that the rotating elements rest on a circular crown base 414. More particularly, such rotating elements 42 rotate from a rest position, in which each rotating element 42 is housed in a defined depression between two successive cams, to a working position in which each rotating element 42 is positioned at each cam, projecting partially from the respective window 413 towards the inside of the shaped hole 401 , and therefore coming into contact by pressing against the ferrule 32 of the spindle 3 to be clamped, holding it in a fixed position.

The intermediate portion 411 of the guide ring 41 provides for a plurality of circumferential windows 413 to house the rotating elements 42, which in addition to the windows 413 have a height corresponding substantially to the thickness of the circular wrench 40. The said windows 413 are configured both to avoid the complete exit of the rotating elements 42 and to allow the partial exit of the rotating elements 42 when they come into contact with the cams of the cam profile 400.

The lower portion 412 of the guide ring 41 is instead configured in such a way as to provide a constraint for the extraction of the guide ring 41 from the circular wrench 40, said constraint for the extraction consists for example of the combined effect of a stop ring 45 housed in a stop ring seat 47 formed on the lower portion 412, said stop ring 45, preferably a Seeger-ring, which in turn blocks a seal ring 44 which in turn holds in place and therefore inside the respective windows 413 the rotating elements 42. It should be noted that both the stop ring 45 and the seal ring 44 can rotate about their axis. The use of a stop ring 45 and a seal ring 44 allows the correct operation of the torque wrench 4 of the system object of the invention.

Inside the shaped hole 401 with cam profile 400 of the circular wrench 40, the ferrule 32 of the spindle 3 is inserted, inside of which, in turn, the shank of the tool to be clamped is inserted. Therefore, by slightly turning the ferrule 32 of the spindle 3 clockwise or anticlockwise, it is possible to lock the spindle 3 in a position, by means of the pressure exerted on the ferrule 32 of the spindle by the rotating elements 42, when they come into contact with the cams of the cam profile 400 of the circular wrench 40. The torque wrench 4 is equipped, inside the handle 48, with a double fixed adjustment mechanism of the clamping torques and a disengagement trigger system of said module in the event the desired clamping torque is reached.

It should be noted that both the torque wrench 4 and the locking device 1 allow rotation both clockwise and anticlockwise of the ferrule 32 and the spindle 3, respectively, in order to allow relative rotation between the ferrule 32 and the spindle 3, so that the jaws 31 open/close to allow the insertion/withdrawal of the tool into/from the spindle 3 or its locking, respectively.

In a further embodiment, the torque wrench 4 can provide for a telescopic handle 48 in order to increase the leverage to optimize the clamping force of the spindle or a piece in general and can be disengaged in order to allow the interchangeability of circular wrenches 40 of different sizes or features with respect to the telescopic handle. The handle 48 comprises a handle portion 480 at the end of which the circular wrench 40 is applied, and a portion of telescopic handle 482 which provides for two or more elements which adapted for sliding telescopically one inside the other extend the overall length of the handle 48. The telescopic handle portion 482 is connected to the handle portion 480 and remains firmly connected thereto by a bayonet joint consisting of a retractable pin 481 housed in the handle portion 480 which retracts into its seat allowing the end of the handle portion 480 to be inserted inside the corresponding end of the telescopic handle portion 482, but which protrudes from a corresponding hole 483 on the telescopic handle portion 482, when the handle portion 480 is connected to the telescopic handle portion 482. Such torque wrench 4 can in any case operate in the absence of the locking device 1 , the spindle 3, the cylindrical bushing 2, but also with suitable additional systems.

In principle, however, the locking device 1 , the spindle 3, the cylindrical bushing 2 and the torque wrench 4 are configured to operate each one individually combined with other systems that are suitable for the purpose.

Further variants in which the elements constituting the locking system are coupled, in different ways, by contraposition of the parts, by engagement, by interlocking, of the constituent elements, or alternative assembly of the elements constituting the module as different embodiments of the transducers or alternative positioning of one or more sensors, as well as variations to the detection module in the parts not strictly related to the innovative module described by the present invention, are to be considered as an object of the present invention, in which also modifications and changes concerning for example the geometries chosen for the individual moving and fixed elements, the materials adopted for each element, and also the specifications of the drive module or modifications to software adaptations, can be made without departing from the scope of the present invention as defined in the appended claims.

List of reference numbers:

1 locking device,

10 cam support

100 cam profile, 101 shaped hole, 102 fixing portion,

11 guide ring

110 upper portion, 111 intermediate portion, 112 lower portion, 113 windows, 114 circular crown base,

12 rotating elements

13 balls

14 seal ring

15 stop ring

16 circular seat

17 stop ring seat

2 cylindrical bushing,

20 cylindrical body

21 longitudinal slots

22 head crown

3 spindle

30 main body

31 jaws

32 ferrule

33a, 33b upper centring portions

34a, 34b lower centring portions

35a, 35b threaded portions

4 torque wrench

40 circular wrench

400 cam profile, 401 shaped hole, 41 guide ring

410 upper portion, 411 intermediate portion, 412 lower portion, 13 windows, 414 circular crown base,

42 rotating elements

44 seal ring

45 stop ring

47 stop ring seat

48 handle

480 handle portion, 481 retractable pin, 482 telescopic handle portion, 483 hole.

Claims

1 . A cold-clamping system of a tool in a spindle, comprising a locking device (1 ) to lock the main cylindrical shaped body (30) of a spindle (3), said locking device (1 ) being configured to retain the main body (30) in a fixed position through the pressure exerted on it by a plurality of rotating elements (12) housed, equally spaced, along the circumference of a guide ring (11 ) adapted for receiving the main body (30) of the spindle (3) therein, said rotating elements (12), which under working condition come into contact with the cams of a cam profile (100) provided for on a cam support (10) of the locking device (1 ), further comprising a torque wrench (4) to lock the ferrule (32) of the spindle (3), said torque wrench (4) configured to retain the ferrule (32) in a fixed position through the pressure exerted on it by a plurality of rotating elements (42) under working condition when they come into contact with the cams of a cam profile (400) provided for on a circular wrench (40) of the torque wrench (4), said rotating elements (42) being equally spaced along the circumference of a guide ring (41 ) of the torque wrench (4) adapted for receiving the ferrule therein (32).

2. The system according to claim 1 further comprising a cylindrical bushing (2) comprising in turn a cylindrical body (20) equipped with longitudinal slots (21 ) which allow the radial pliability of the lateral surface of the cylindrical body (20) when subjected to the thrust exerted by the rotating elements (12) due to the cams of the cam profile (100) when the cylindrical bushing (2) is inserted for use inside the guide ring (11 ) of the locking device (1 ), further comprising a head crown (22) free to rotate about its axis above the cylindrical body (20) and thereto interlock against the longitudinal extraction in the direction of its axis.

3. The system according to the preceding claims, wherein the rotating elements (12) and the rotating elements (42) consist of rollers.

4. The system according to the preceding claims, wherein the rotating elements (12) are housed inside seats equipped with windows (113) obtained along the inner circumference of a guide ring (11 ) of the locking device (1 ), said windows (113) configured both to avoid the complete exit of the rotating elements (12) and to allow the partial exit of the rotating elements (12) when they come into contact with the cams of the cam profile (100) when in use, and wherein the rotating elements (42) are housed inside seats equipped with windows (413) obtained along the inner circumference of a guide ring (41 ) of the torque wrench (4), said windows (413) configured both to avoid the complete exit of the rotating elements (42) both to allow the partial exit of the rotating elements (42) as they come into contact with the cams of the cam profile (400) when in use.

5. The system according to claim 4, wherein the guide ring (11 ) comprises an upper portion (110) in which a circular seat (16) is obtained, where a plurality of balls (13) are housed, which allow rotation between the guide ring (11 ) and the cam support (10).

6. The system according to claims 4 and 5, wherein the guide ring (11 ) comprises a lower portion (112) configured in such a way as to provide a restriction for the extraction of the guide ring (11 ) from the cam support (10), and wherein a lower portion (412) of the guide ring (41 ) is configured in such a way as to provide a restriction for the extraction of the guide ring (41 ) from the circular wrench (40).

7. The system according to claims 4, 5 and 6, wherein the said restriction for the extraction of the guide ring (11 ) from the lower portion (112) consists of the combined effect of a stop ring (15), housed in a seat (17) made on the lower portion (112), said stop ring (15) which in turn blocks a seal ring (14) which in turn blocks inside the respective seats equipped with windows (113) the rotating elements (12), and wherein the said restriction for the extraction of the guide ring (41 ) from the lower portion (412) consists of the combined effect of a stop ring (45), housed in a seat (47) made on the lower portion (412), said stop ring (45), which in turn blocks a seal ring (44) which in turn blocks inside the respective seats equipped with windows (413) the rotating elements (42), and wherein both the stop rings (15, 45) and the seal rings (14, 44) can rotate about their axis.

8. The system according to the preceding claims, wherein said spindle (3) comprises a main body (30) which ends with a plurality of jaws (31 ) adapted for radially approaching each other and then to clamp the shank of the tool to be blocked by means of a ferrule (32), wherein the jaws (31 ) have a conical profile, and provide for on their outer surface a conical thread capable of coupling with a corresponding conical counter-thread provided for inside the ferrule (32).

9. The system according to claim 8, wherein the main body (30) comprises an upper centring portion (33a) and a lower centring portion (34a) configured to couple with a corresponding upper centring portion (33b) and a lower centring portion (34b) provided for inside the ferrule (32), respectively, as well as the main body (30) in which a threaded portion (35a) is adapted for screwing to a corresponding threaded portion (35b) provided for inside the ferrule (32).

10. The system according to the preceding claims, wherein the torque wrench (4) comprises a telescopic handle portion (482).

11 . The system according to claim 10, wherein the telescopic handle portion

(482) can be released from a handle portion (480) of the handle (48) and can be firmly connected thereto via a bayonet joint (481 , 483).

12. System according to claim 11 , wherein the closing means (481 , 483) consists of a retractable pin (481 ) housed in the handle portion (480) and a hole

(483) present on the telescopic handle portion (482).