Device for quickly changing a tool

Abstract

The present invention relates to a quick-change device (1) for removably fastening a tool (2) to a shaft (3), which comprises a screwing body (4), a knob (5), an abutment body (6), force application means (7a), and force multiplier means (7b). The screwing body (4) extends along a device axis (D) between a proximal end (4a) and an opposing distal end (4b). The screwing body also comprises a closing flange (41) provided with a projection (410) protruding towards the device axis (D). The knob (5) is engaged with the closing flange (41) and comprises an annular ridge (510) protruding outwards which engages the projection (410) in a freely sliding manner along the device axis (D). The abutment body (6) is engaged with the screwing body (4) and is suitable for abutting against the tool (2). The force application means (7a) are operable by means of the knob (5) and generate a preload force. The force multiplier means (7b) operatively connect the force application means (7a) to the abutment body (6) and allow the preload force to be increased.

Description

"DEVICE FOR QUICKLY CHANGING A TOOL"DESCRIPTION

[0001] The present invention is in the technical field of devices for rapidly changing tools without the use of particular instruments . In this case , the device for rapidly changing a tool , obj ect of the present invention, does not require the use of instruments such as screwdrivers , grippers , keys or Allen wrenches , and for this reason it is also referred to as a " tool-less" quick-change device .

[0002] For the purposes of this discussion, the term " tool" refers to a disk blade , a circular saw, a cutter, or the like . The tool is suitable for being operatively connected to , and made integral with, a rotating shaft in such a way that the rotation of the shaft is trans ferred to the tool .

[0003] The term " quick-change device" means any device that allows the tool to be quickly connected and locked onto the shaft , and that also allows the tool to be removed from the shaft in such a way that it may be replaced j ust as quickly .

[0004] As is well known, various types of devices have already been developed which allow a tool to be locked onto a shaft quickly and replaced j ust as quickly, without using special instruments .

[0005] A first solution has been developed by the Felder KG company and described in the patent EP2210720B1 , wherein the quick-change device comprises a clamping disk that is suitable for abutting against the tool and a force transmission element . An intermediate flange , that is rigidly connected to the clamping disk, is furthermore interposed between the clamping disk and the force transmission element . The device may be screwed to a drive shaft by means of a screw ( central pin) that is centrally engaged with the clamping disk . A force reduction mechanism is positioned between the force transmission element and the screw, which force reduction mechanism comprises an axially translatable ball , a plurality of spheres and a spring that is interposed between the ball and the screw . The axial displacement of the ball results in a radial movement of the spheres which trans fer a preload force to the clamping disk in such a way as to push the aforesaid clamping disk against the tool .

[0006] Furthermore , the spring which is compressed by the translation of the ball , serves to facilitate the retraction of the ball when the preload force is removed, for example when the quick-change device is unscrewed from the shaft in order to allow for maintenance / replacement of the tool .

[0007] The force transmission element comprises a tang which may be screwed onto the intermediate flange , in such a way that , by screwing the force transmission element onto the intermediate flange , the tang presses against the ball , thereby provoking the axial translation thereof . The displacement of the ball determines the radial motion of the plurality of spheres that exert the preload force upon the clamping disk . The mutual interaction between the ball and the plurality of spheres housed within the respective seats thereof allows an operator to screw the tang into the intermediate flange with relative simplicity, insofar as the preload force is ampli fied by the radial motion of the spheres which are actuated by the displacement of the ball .

[0008] In conclusion, the device described in EP2210720B1 provides for simply screwing the screw into the drive shaft until the clamping disk is abutted against the tool . The force transmission element is then rotated in such a way as to screw it into the intermediate flange so as to move the ball axially, radially displace the spheres , respectively housed within semi-cylindrical cots obtained in a ring, and apply the preload force to the clamping disk .

[0009] Disadvantageously, in EP2210720B1 the force transmission element provided with the tang may besubj ect to unscrewing during normal tool use , for example due to vibrations . In fact , the device described in EP2210720B1 comprises anti-unscrewing means for the force transmission element ; however, such anti-unscrewing means work by friction and do not mechanically engage the force transmission element in such a way as to prevent the tang from accidentally unscrewing . It is clear that in the event of the accidental unscrewing of the force transmission element , the preload force acting upon the clamping disk is reduced and the tool connection to the shaft may therefore loosen during normal operation .

[0010] A further disadvantage of the device described in EP2210720B1 relates to the seats of the plurality of spheres , which require heat treatment of hardening and subsequent finishing . The quick-change device developed by the Felder KG company therefore requires complex and economically costly processing .

[0011] A further solution is described in DE2823609A1 , wherein the transmission element translates axially and displaces a central ball which in turn pushes three angularly equally spaced spheres radially outwards . Due to the radial displacement of the three spheres , the device constrains the tool to the drive shaft . The housing that accommodates the radial motion of the three spheres is however formed directly in the tool , or elsein the drive shaft .

[0012] An alternative solution was proposed in US 9089989B2 , wherein the rotation of the force transmis sion element actuates an epicycloidal reducer that increases the clamping torque on the central pin in such a way as to connect and lock the tool to the drive shaft .

[0013] Disadvantageously, the epicycloidal reducer is structurally complex to manufacture and inconvenient from an economic point of view .

[0014] Further examples of quick-change devices are described in DE10258372B4 , DE102013227219A1 , EP1839826A1 , US 8776657B2 , US2004 / 0228701A1 , W02015 / 075001A1 .

[0015] The obj ect of the present invention is to propose a quick-change device for removably fastening a tool to a shaft and obviating at least part of the drawbacks mentioned above .

[0016] Said obj ect is achieved with a tool according to claim 1 . The dependent claims describe preferred embodiments of the invention .

[0017] The features and advantages of the device according to the invention shall be made apparent from the following description of preferred embodiments thereof , provided purely by way of non-limiting example , with reference to the accompanying figures , in which :- Figure 1 is an axial section of a quick-change deviceaccording to the present invention in a first embodiment , wherein di f fering gray-scale color hatches are associated with various rigid bodies of the device that are suitable for moving themselves relative to one another;- Figure 2 is the same axial section of the device of Figure 1 with a knob in a retracted position and with the device in an inactive configuration;- Figure 2a is an axial section of the device of Figure 2 with the knob in an advanced position and with the device in an inactive configuration;- Figure 2b is an axial section of the device of Figure 2 with the knob in a retracted position and with the device in an active configuration;- Figure 3 is an axial section of the device of Figure 2 along a di f ferent sectional plane ;- Figure 4 is a sectional view obtained along the line IV- IV of Figure 3 ;- Figure 5 is a sectional view obtained along the line V- V of Figure 3 ;- Figure 6 is a sectional view obtained along the line VI-VI of Figure 3 ;- Figure 7 is a perspective view with separate components of a group comprising the device , a tool and a shaft ;- Figure 8 is an axial section of the group of Figure 7 ;- Figure 9 is an axial section of the device according tothe present invention in a second embodiment with the knob in a retracted position and with the device in an inactive configuration;- Figure 9a is an axial section of the device of Figure 9 with the knob in an advanced position and with the device in an inactive configuration;- Figure 9b is an axial section of the device of Figure 9 with the knob in a retracted position and with the device in an active configuration;- Figure 10 is an axial section of the device of Figure 9 along a di f ferent sectional plane ;- Figure 11 is an exploded perspective view of the device in the second embodiment ; and- Figure 12 is an axial section of the device according to the present invention in a third embodiment with the knob in a retracted position and with the device in an inactive configuration .

[0018] In the following description, elements common to the various embodiments represented in the drawings are indicated with the same reference numerals .

[0019] In said drawings , a quick-change device according to the invention has been collectively indicated with 1 .

[0020] The device 1 is suitable for removably fastening a tool 2 to a shaft 3 , preferably a drive shaft .

[0021] The device comprises a screwing body 4 , a knob 5 , anabutment body 6, force application means 7a and force multiplier means 7b (Figure 1) .

[0022] The screwing body 4 extends axially along a device axis D between a proximal end 4a, suitable for engaging the shaft 3, and an opposing distal end 4b.

[0023] For the purposes of this discussion, the term "axial" (and the relative derivatives) is to be understood as referring to the device axis D. For example, the axial section is obtained with a section plane containing the device axis D; the axial extension refers to a direction parallel to the aforementioned device axis D.

[0024] The term "proximal" (and derivatives) refers to a position of proximity to the tool 2; vice versa, the term "distal" (and derivatives) is associated with a position of distance from the tool 2.

[0025] Finally, the device, object of the present invention, delimits an "inner" space that counters an "outer" space. It is clear that the phrase "inwards" refers to a direction facing the device axis D, i.e., facing the inner space delimited by the device 1; vice versa, the phrase "outwards" refers to a direction oriented so as to move away from the device axis D.

[0026] The screwing body 4 comprises a closing flange 41 provided with a projection 410 protruding towards thedevice axis D in such a way as to define an undercut . In particular, the closing flange 41 is positioned at the distal end 4b .

[0027] The proj ection 410 preferably protrudes radially inwards .

[0028] The knob 5 is engaged with the closing flange 41 and comprises an annular ridge 510 protruding outwards and housed in the undercut so as to freely engage the proj ection 410 along the device axis D in a sliding manner .

[0029] The annular ridge 510 preferably protrudes radially, i . e . , orthogonally to the device axis D, and is oriented outwards .

[0030] The engagement between the annular ridge 510 and the proj ection 410 rotationally blocks the knob 5 but allows its translation along the device axis D . Conversely, the disengagement of the annular ridge 510 from the proj ection 410 allows for both the rotation and the axial displacement of the knob 5 .

[0031] In this case , housing the annular ridge 510 in the undercut prevents the decoupling of the knob 5 from the screwing body 4 ; in other words , the knob 5 and the screwing body 4 are not separable therebetween .

[0032] The abutment body 6 is engaged with the screwing body 4 and is suitable for abutting against the tool 2 insuch a way as to connect and render the aforesaid tool 2 integral with the shaft 3 .

[0033] The force application means 7a are operable by means of the knob 5 . Such force application means 7a generate a preload force suitable for pushing the abutment body 6 against the tool 2 .

[0034] The force multiplier means 7b operatively connect the force application means 7a with the abutment body 6 .

[0035] The operation of the force application means 7a is achieved by axially moving the knob 5 so as to disengage the annular ridge 510 from the proj ection 410 . Subsequently, by rotating the knob 5 , a displacement of the force application means 7a is obtained in such a way as to actuate the force multiplier means 7b .

[0036] The force multiplier means 7b increase the preload force acting upon the abutment body 6 and generated by the force application means 7a, in such a way as to push the abutment body 6 against the tool 2 .

[0037] In particular, the translation along the device axis D of the force application means 7a - due to the rotation of the knob 5 - generates the preload force which is ampli fied by the force multiplier means 7b in such a way as to press the abutment body 6 against the tool 2 .

[0038] The force application means 7a preferably move in an axial direction .

[0039] The quick-change device may be arranged in the inactive configuration ( Figures 2 , 2a, 3 , 9 , 9a, 10 and 12 ) or in the active configuration ( Figures 2b and 9b ) . With the device in the active configuration, the force application means 7a are translated in such a way as to actuate the force multiplier means 7b which press the abutment body 6 against the tool 2 ; on the other hand, with the device in the inactive conf iguration, it is not possible to apply the preload force necessary to push the abutment body 6 against the tool 2 and thus render the tool 2 integral with the shaft 3 .

[0040] The knob 5 is axially movable between a retracted position ( Figures 2 , 2b, 9 , 9b and 12 ) and an advanced position ( Figures 2a and 9a ) . In the retracted position, the annular ridge 510 and the proj ection 410 are mutually engaged in such a way as to block the rotation of the knob 5 , which in any case remains free to translate along the device axis D . In the advanced position, the knob 5 is moved in a proximal direction along the device axis D, causing the disengagement of the annular ridge 510 from the proj ection 410 , and is therefore free to rotate about the device axis D .

[0041] Only when the knob 5 is in the advanced position, i . e . , it may rotate freely, is it possible to arrange the device 1 in an active configuration insofar as , byrotating the knob 5 , the force application means 7a translate in such a way as to actuate the force multiplier means 7b .

[0042] It should be noted that the knob in an advanced position, with the annular ridge 510 decoupled from the proj ection 410 , does not necessarily imply that the device 1 is in an active configuration . The transition from the inactive to the active configuration is only achieved by rotating the knob 5 to the advanced position, insofar as said rotation provokes the axial translation of the force application means 7a . Similarly, when the knob 5 is in the retracted position, it does not necessarily mean that the device 1 is in an inactive configuration; in fact , after the rotation of the knob 5 to the advanced position has caused the axial translation of the force application means 7a, the knob 5 may be returned to the retracted position without canceling the preload force , insofar as such preload force is ensured by the actuation of the force multiplier means 7b on the part of the force application means 7 a .

[0043] The knob 5 in the advanced position therefore allows the force application means 7a to be translated axially, but it is the force application means that generate the preload force that is then ampli fied by the force multiplier means 7b . This preload force is completelyindependent of the knob 5 , insofar as the force application means 7a are responsible for the actuation of the force multiplier means 7b .

[0044] A clamping disk 31 is preferably interposed between the quick-change device 1 and the tool 2 ( see Figures 7- 8 ) . Furthermore , a further clamping disk 32 is also interposed between the tool 2 and the shaft 3 ( see Figures 7- 8 ) . After engaging the quick-change device 1 with the shaft 3 , by means of manual screwing, the tool 2 is brought to abut against the shaft 3 on one side ( or preferably against the further clamping disk 32 which is integral with the shaft 3 ) and on the opposite side it abuts with the quick-change device 1 ( or preferably with the clamping disk 31 where present ) ; thus , the quick- change device is in an inactive configuration . It is subsequently possible to arrange the quick-change device in an active configuration in such a way as to apply the preload force necessary to render the tool 2 integral with the shaft 3 .

[0045] The quick-change device 1 has strong axial symmetry in relation to the device axis D, i . e . it is predominantly axisymmetric .

[0046] In one embodiment , the mutual engagement between the screwing body 4 and the abutment body 6 defines a preload chamber 8 .

[0047] The device 1 comprises a plurality of sealing elements 10 , interposed between the screwing body 4 and the abutment body 6 . Such sealing elements 10 comprise primary sealing elements 10 ' suitable for preventing dirt , dust and / or debris from entering the preload chamber 8 . The primary sealing elements 10 ' are , for example , gaskets .

[0048] According to one embodiment , the force application means 7a comprise a threaded stud 71 , a ball 72 and a first elastic element 73 .

[0049] The threaded stud 71 is engaged in the screwing body 4 and is at least partially housed within the preload chamber 8 .

[0050] The ball 72 is housed in the preload chamber 8 and abuts against the threaded stud 71 in such a way that , by screwing the threaded stud 71 into the screwing body 4 , the ball 72 is pushed in an axial direction towards the abutment body 6 .

[0051] The first elastic element 73 is interposed between the ball 72 and the abutment body 6 . This first elastic element 73 is compressed by the axial advancement of the ball 72 and facilitates the retraction of the ball 72 upon the release of the preload force .

[0052] In particular, the first elastic element 73 favors the retraction of the bal l 72 in a distal direction alongthe device axis D, in such a way as to restore the inactive configuration of the device 1 . The relaxation of the first elastic element 73 is due to the removal of the preload force and promotes the retraction of the ball 72 from the abutment body 6 .

[0053] The aforesaid first elastic element 73 is , for example , a wavy spring .

[0054] An interface washer 730 is also provided between the ball 72 and the first elastic element 73 which improves the mutual engagement between the ball 72 and the first elastic element 73 .

[0055] In particular, the threaded stud 71 is decoupled from the knob 5 and, when the device 1 is in an active configuration, such threaded stud 71 holds the force multiplier means 7b in place in such a way that they may increase the preload force necessary to render the tool 2 integral with the shaft 3 .

[0056] The screwing body 4 preferably comprises a screwing flange 42 positioned at the proximal end 4a . Said screwing flange 42 further comprises a screw 43 protruding axially so as to engage the shaft 3 . In this case , the screw 43 protrudes in a proximal direction towards the tool 2 and is screwable into a recess obtained in the shaft 3 .

[0057] In one embodiment , the screw 43 is engaged in ascrew hole 430 which is a through-hole and which is obtained within the screwing flange 42. Alternatively, the screw 43 and the screwing flange 42 are made as one piece, i.e., in a single body.

[0058] The quick-change device 1 shown in the attached Figures 2, 7 and 8 is screwed onto a fixed part, for example the shaft of a cutter, by means of the screw 43. Between the fixed part and the abutment body 6 there is the tool 2 to be clamped, typically the blade of a cutter provided with respective clamping disks 31, 32 (see Figures 7-8) . By screwing manually, the quick-change device 1 is brought into contact with the tool 2 (with the possible interposition of the clamping disk 31) , but without imparting any preload. The preload is imparted subsequently by pressing the knob 5 and rotating it until the preload is such that it is no longer possible to screw the knob 5 by hand any further. At this point the group (comprising the device 1, tool 2, and shaft 3) is preloaded and it is sufficient to perform the opposite operation to unlock it.

[0059] In one embodiment, the plurality of sealing elements 10 also comprises a secondary sealing element 10", for example an elastic gasket, positioned between the screw 43 and the abutment body 6. Such secondary sealing element 10" allows the screw 43 to be maintained inabutment against the screwing flange 42 .

[0060] According to one embodiment , the screwing body 4 also comprises a support element 44 positioned between the closing flange 41 and the screwing flange 42 . Said support element 44 is connected to and made integral with both the closing flange 41 and the screwing flange 42 , so as to make the screwing body 4 monolithic .

[0061] Preferably, the rotation of the knob 5 in the advanced position causes the threaded stud 71 to move forwards , which threaded stud screws into the support element 44 and pushes the ball 72 ; in turn, the ball 72 actuates the force multiplier means 7b and compresses the first elastic element 73 . In this way, the preload force is generated and multiplied in such a way that the abutment body 6 is compressed between the force multiplier means 7b and the tool 2 .

[0062] In one embodiment , the abutment body 6 is interposed between the support element 44 and the screwing flange 42 . The support element 44 and the screwing flange 42 are connected to each other by means of a plurality of mechanical connection elements 45 , for example said plurality of mechanical connection elements 45 comprises threaded connections 45 ' and spacers 45" .

[0063] A plurality of through holes 65 with a diameter larger than the mechanical connection elements 45 isobtained within the abutment body 6 , so that the mechanical connection elements 45 engage the respective plurality of through holes 65 with clearance . In other words , the mechanical connection elements 45 are limited only to passing through the abutment body 6 and are not used to connect the screwing body 4 to the abutment body 6 . The screwing body 4 and the abutment body 6 are therefore slidably free to move along the device axis D relative to each other .

[0064] A threaded through hole 440 is preferably formed in the support element 44 , which is engageable by the force application means 7a . In this case , this threaded hole 440 is engaged by the threaded stud 71 which translates axially in being screwed into said threaded hole 440 .

[0065] By virtue of the connection between the threaded stud 71 and the threaded hole 440 , the reaction to the thrust of the ball 72 is discharged onto the screwing body 4 .

[0066] In this case , by virtue of the fact that the knob 5 and the threaded stud 71 are slidably free to move along the device axis D, the knob 5 allows the force application means 7a to be actuated, in particular the rotation of the knob 5 allows the threaded stud 71 to be screwed into the threaded hole 440 , but is not in any way af fected by the preload force .

[0067] In one embodiment , the abutment body 6 comprises a preload distribution ring 61 provided with a conical surface 610 facing towards the device axis D . The conical surface 610 forms an inclination angle a with an imaginary plane I orthogonal to the device axis D .

[0068] The abutment body 6 comprises a collar 62 protruding axially towards the knob 5 and internally delimiting a compartment 63 wherein the first elastic element 73 is housed .

[0069] Furthermore , the preload distribution ring 61 is fitted externally around the collar 62 .

[0070] Going into more detail , the collar 62 is distally delimited by an edge 62 ' which is configured as a proximal end stop for the ball 72 , i . e . , the maximum axial translation of the ball 72 towards the tool 2 is obtained when the ball 72 is in contact with the edge 62 ' of the collar 62 ( Figures 2b and 9b ) .

[0071] Preferably, the collar 62 is positioned in the preload chamber 8 .

[0072] According to one embodiment , the force multiplier means 7b comprise a plurality of spheres 74 movable along the conical surface 610 of the preload distribution ring 61 . Such spheres 74 are in contact with the ball 72 in such a way that the ball 72 , in moving axially towards the abutment body 6 , pushes the spheres 74 outwards .

[0073] In particular, the spheres 74 translate by sliding along the conical surface 610 of the preload distribution ring 61 .

[0074] Furthermore , the spheres 74 , in moving away from the device axis D, multiply the preload force generated by the force application means 7a and trans fer such preload force to the abutment body 6 in such a way as to push the abutment body 6 against the tool 2 . In this case , the preload force ampli fied by the spheres 74 is suitable for pushing the abutment body 6 against the tool 2 . It should be noted that the spheres 74 are pushed outwards by the ball 72 and ampli fy the preload force which, due to the contact of the spheres 74 along the conical surface 610 , may be decomposed into an axial compression force , trans ferred to the abutment body 6 , and a radial force , orthogonal to the device axis D .

[0075] According to one embodiment , the screwing body 4 comprises a thrust washer 46 that is in contact with the plurality of spheres 74 . Said thrust washer 46 is configured to absorb an axial force applied to the screwing body 4 and is due to the contact of the spheres 74 along the conical surface 610 of the preload distribution ring 61 .

[0076] The thrust washer 46 is preferably a tempered and straightened commercial component , i . e . , it isstructurally capable of absorbing axial force ; in thi s way, it is possible to avoid the thermal tempering treatment of the support element 44 .

[0077] The force multiplier means 7b interact with the thrust washer 46 , with the ball 72 , and with the conical surface 610 to multiply the preload force . In this case , the advancement of the ball 72 , obtained by means of a reduced screwing force of the threaded stud 71 into the screwing body 4 by means of the knob 5 , results in a reduced outwards movement of the spheres 74 and therefore in an increase in the preload force which the spheres 74 trans fer to the abutment body 6 . In other words , the displacement of the threaded stud 71 , screwed into the screwing body 4 , is greater than the displacement of the spheres 74 that move along the conical surface 610 .

[0078] In one embodiment , the screwing body 4 is provided with a slanted wall 47 facing towards the ball 72 , which is configured as a distal limit stop for the ball 72 . The maximum axial translation of the ball 72 towards the knob 5 is therefore achieved when the ball 72 is in contact with the slanted wall 47 of the screwing body 4 .

[0079] The device 1 further comprises a second elastic element 12 that elastically connects the knob 5 and the force application means 7a to each other . In particular, the second elastic element 12 elastically connects theknob 5 and the threaded stud 71 to each other . Such second elastic element 12 is preferably a helical spring .

[0080] According to one embodiment , the threaded stud 71 comprises a head 710 and in the knob 5 a recess 50 is obtained in which the aforesaid head 710 is at least partially housed ( Figure 3 ) .

[0081] Furthermore , the head 710 engages the recess 50 by shape coupling so that , following the disengagement of the annular ridge 510 from the proj ection 410 , the rotation of the knob 5 causes a rotation of the threaded stud 71 .

[0082] Preferably, the coupling between the head 710 and the recess 50 is a square connection, wherein the cross section of the recess 50 is quadrangular in shape and the head is substantially counter-shaped with respect to the recess 50 ( Figure 5 ) .

[0083] The knob 5 and the threaded stud 71 are slidably free to translate with respect to each other along the device axis D, but are rotationally integral therebetween .

[0084] According to one embodiment , a housing hole 52 ; 712 is obtained in the head 710 of the threaded stud 71 and in a bottom wall 51 of the recess 50 , respectively, in order to accommodate the second elastic element 12 .

[0085] With the device 1 in an active configuration, theknob 5 returns from the advanced position to the retracted position, by virtue of the second elastic element 12 , which axially moves the knob 5 away from the force application means 7a and allows the engagement between the annular ridge 510 and the proj ection 410 to be restored . The return of the knob 5 to the retracted position is therefore completely independent of the threaded stud 71 - which is screwed into the support element 44 - and depends exclusively on the second elastic element 12 which is compressed during the transition from the retracted position to the advanced position and relaxes , thereby returning the knob 5 to the retracted position .

[0086] The knob 5 makes it possible to adj ust the screwing, i . e . the axial advancement , of the threaded stud 71 into the support element 44 , but it is completely independent of the force application means 7a, insofar as the retracted or advanced position of the knob 5 is determined by the compression of the second elastic element 12 . By compressing the second elastic element 12 , the knob 5 translates to an advanced position and, in releasing the pressure exerted on the knob 5 , the second elastic element 12 returns the knob 5 to a retracted position . On the other hand, the active or inactive configuration of the device 1 depends exclusively on theforce application means 7a which, with the device in an active configuration, are suitable for pushing the abutment body 6 against the tool 2 in such a way as to render the tool 2 integral with the shaft 3 .

[0087] The threaded stud 71 , at a proximal end opposite the position of the head 710 , comprises a washer 713 and a nut 714 which are configured as limit stop elements and prevent the threaded stud 71 from unscrewing from the screwing body 4 , in particular from the support element 44 .

[0088] A plurality of pins 48 is preferably fixed to the proj ection 410 and a plurality of openings 58 which are engageable by the aforementioned plurality of pins 48 , and vice versa, is respectively obtained on the annular ridge 510 .

[0089] In particular, the screwing body 4 comprises the plurality of pins 48 fixed to , and made integral with, the proj ection 410 , whilst the plurality of openings 58 , respectively engageable by the plurality of pins 48 , is obtained on the annular ridge 510 . Alternatively, the knob 5 comprises the plurality of pins , which are fixed to , and made integral with, the annular ridge 510 , whilst the plurality of openings , which may respectively be engaged by the plurality of pins , is obtained on the proj ection 410 .

[0090] The mutual engagement between the pins 48 and the respective openings 58 rotationally blocks the knob 5 ; however, it allows the knob 5 to translate axially between the advanced position, wherein the second elastic element 12 is compressed, and the retracted position, wherein the second elastic element 12 is at rest or less compressed than in the advanced position .

[0091] In an embodiment shown in the accompanying Figures 9- 9b, 10 and 11 , the engagement between the proj ection 410 and the annular ridge 510 is due to a pair of toothed ring nuts 49 , 59 . A first ring nut 49 of the pair of toothed ring nuts is fixed to the proj ection 410 , whilst the second ring nut 59 of the pair of toothed ring nuts is fixed to the annular ridge 510 . The mutual engagement of the pair of toothed ring nuts 49 , 59 rotationally blocks the knob 5 , but allows the knob 5 to translate axially, for example between the retracted position and the advanced position .

[0092] According to a further embodiment shown in the accompanying Figure 12 , the abutment body 6 also comprises a bottom plate 66 provided with a protrusion 67 which engages the screwing body 4 . This bottom plate 66 acts as a bottom surface of the compartment 63 in which the first elastic element 73 is housed .

[0093] The protrusion 67 preferably engages the screw 43 ofthe screwing body 4 .

[0094] According to one embodiment , the abutment body 6 also comprises a plurality of separation pins 68 fixed to the aforesaid abutment body 6 . Such separation pins 68 are configured so as to maintain the spheres 74 angularly spaced from one another ( Figure 6 ) . In particular, the separation pins 68 pass through the entire axial length of the preload distribution ring 61 and protrude axially both towards the knob 5 , in order to maintain the spheres 74 angularly evenly spaced apart , and towards the tool 2 , in order to anchor themselves to the abutment body 6 .

[0095] The separation pins 68 are preferably equal in number to the number of spheres 74 .

[0096] According to one embodiment , shown in the accompanying Figures 3 and 10 , at least one seat 420 facing the abutment body 6 is obtained in the screwing flange 42 . A third elastic element 13 is positioned within each seat 420 . The actuation of the force application means 7a determines an axial displacement of the abutment body 6 towards the tool 2 and such axial displacement provokes compression of the aforementioned third elastic element 13 . The compression of the third elastic element 13 allows the abutment body 6 to retract upon the release of the preload force . The third elastic element 13 is for example a corrugated or helical spring .

[0097] Innovatively, the device , obj ect of the present invention, entirely ful fills the intended obj ect thereof .

[0098] Advantageously, the quick-change device is able to generate a preload force that is comparable to the tightening torque of the screw without using any particular instruments , such as screwdrivers , grippers , keys , Allen wrenches , or the like .

[0099] According to one advantageous aspect , the preload force is generated by actuating the force application means and increased by the force multiplier means only after bringing the abutment body into abutment against the tool . In particular, after having engaged the screw in the shaft , the preload force is generated by arranging the knob in an advanced position and rotating the aforesaid knob in such a way as to provoke the displacement of the force multiplier means . By axially moving the threaded stud towards the tool , the ball pushes the spheres outwards in such a way as to ampli fy the preload force and to make the tool integral with the shaft .

[0100] According to a still further advantageous aspect , the device is extremely balanced; in fact , the separation pins maintain the spheres angularly evenly spaced apart , in such a way that eccentric masses , that could lead to vibrations , are not produced .

[0101] Advantageously, the device is structurally simpler than the solutions that are currently available on the market , insofar as only the preload distribution ring requires both heat treatment ( e . g . , hardening) and mechanical processing ( e . g . , grinding) . On the other hand, all of the other components of the device are either directly commercially available components or are obtainable using mechanical processing only ( for example by turning) without heat treatment .

[0102] According to one advantageous aspect , the knob serves only to actuate the force application means and is therefore not responsible for the preload force . By virtue of the square connection, by pressing and rotating the knob, it is possible to screw the threaded stud into the screwing body . Thus , the knob and the threaded stud - whilst rotationally integral therebetween - are slidably free to translate with respect to one another along the device axis .

[0103] According to a still further advantageous aspect , the mutual engagement between the proj ection and the annular ridge is configured with a safety system that prevents the knob from accidentally unscrewing .

[0104] To the embodiments of the device according to the invention, a person skilled in the art , in order to meet contingent needs , may make modi fications ,adaptations and replacements of elements with functionally equivalent ones , without leaving the scope of protection of the fol lowing claims . Each of the features described as belonging to a possible embodiment may be obtained independently in the other described embodiments .

Claims

CLAIMS1. A quick change device (1) for removably fastening a tool (2) to a shaft (3) , preferably a drive shaft, said device comprising:- a screwing body (4) extending axially along a device axis (D) between a proximal end (4a) suitable to engage the shaft and an opposing distal end (4b) , said screwing body comprising a closing flange (41) provided with a projection (410) protruding towards the device axis (D) so as to define an undercut;- a knob (5) engaged with the closing flange (41) , said knob comprising an annular ridge (510) protruding outwards and housed in the undercut to engage the projection (410) in a slidingly free along the device axis (D) ;- an abutment body (6) engaged with the screwing body (4) and suitable to abut against the tool (2) to connect said tool (2) to the shaft (3) ;- force application means (7a) operable by means of the knob (5) , said force application means (7a) generating a preload force to push the abutment body (6) against the tool (2) ;- force multiplier means (7b) operatively connecting the force application means (7a) to the abutment body (6) , wherein the operation of the force application means (7a)is obtained by axially moving the knob (5) to disengage the annular ridge (510) from the projection (410) and then rotating said knob (5) so as to cause a displacement of the force application means (7a) so as to operate the force multiplier means (7b) , said force multiplier means (7b) increasing the preload force acting on the abutment body (6) and generated by the force application means (7a) , so as to push the abutment body (6) against the tool (2) .

2. Device according to the preceding claim, wherein the mutual engagement between the screwing body (4) and the abutment body (6) defines a preload chamber (8) .

3. Device according to the preceding claim, comprising a plurality of sealing elements (10) interposed between the screwing body (4) and the abutment body (6) , said plurality of sealing elements (10) comprising primary sealing elements (10' ) suitable to prevent dirt, dust and / or debris from entering into the preload chamber (8) .

4. Device according to claim 2 or 3, wherein the force application means (7a) comprise:- a threaded stud (71) engaged in the screwing body (4) and at least partially housed in the preload chamber (8) ; a ball (72) housed in the preload chamber (8) and abutting against the threaded stud (71) so that, by screwing the threaded stud (71) in the screwing body (4) ,the ball (72) is pushed in the axial direction towards the abutment body (6) ;- a first elastic element (73) , such as a wavy spring, for example, interposed between the ball (72) and the abutment body (6) , said first elastic element (73) being compressed by the axial advancement of the ball (72) and promoting the retraction of the ball (72) upon the release of the preload force.

5. Device according to any one of the preceding claims, wherein the screwing body (4) comprises a screwing flange (42) positioned at the proximal end (4a) , said screwing flange (42) further comprising a screw (43) protruding axially to engage the shaft (3) .

6. Device according to the preceding claim, wherein the screwing body (4) also comprises a support element (44) positioned between the closing flange (41) and the screwing flange (42) , said support element (44) being connected to and made integral with both the closing flange (41) and the screwing flange (42) so as to make the screwing body (4) monolithic.

7. Device according to the preceding claim, wherein the abutment body (6) is interposed between the support element (44) and the screwing flange (42) , the support element (44) and the screwing flange (42) being connected to each other by means of a plurality of mechanicalconnection elements (45) , for example said plurality of mechanical connection elements (45) comprising threaded connections (45' ) and spacers (45") , and wherein a plurality of through holes (65) is obtained in the abutment body (6) , with a larger diameter than the mechanical connection elements (45) , so that the mechanical connection elements (45) engage the respective plurality of through holes (65) with clearance.

8. Device according to claim 6 or 7, wherein in the support element (44) is obtained a threaded through hole (440) engageable by the force application means (7a) .

9. Device according to any one of the preceding claims, wherein the abutment body (6) comprises a preload distribution ring (61) provided with a conical surface (610) facing the device axis (D) , said conical surface (610) forming an inclination angle (a) with an imaginary plane (I) orthogonal to the device axis (D) .

10. Device according to the preceding claim in combination with claim 4, wherein the abutment body (6) comprises a collar (62) protruding axially towards the knob (5) and internally delimiting a compartment (63) where the first elastic element (73) is housed, and wherein the preload distribution ring (61) is externally fitted around the collar (62) .

11. Device according to any one of the preceding claimsin combination with claims 4 and 9, wherein the force multiplier means (7b) comprise a plurality of spheres (74) movable along the conical surface (610) of the preload distribution ring (61) , said spheres (74) being in contact with the ball (72) so that the ball (72) , moving axially towards the abutment body (6) , pushes the spheres (74) outwards, wherein said spheres (74) , moving away from the device axis (D) , multiply the preload force generated by the force application means (7a) and transfer said preload force to the abutment body (6) to push said abutment body (6) against the tool (2) .

12. Device according to the preceding claim, wherein the screwing body (4) comprises a thrust washer (46) in contact with the plurality of spheres (74) , said thrust washer (46) being configured to absorb an axial force applied to the screwing body (4) and due to the contact of the spheres (74) along the conical surface (610) .

13. Device according to any one of the preceding claims in combination with claim 4, wherein the screwing body (4) is provided with a slanted wall (47) facing the ball (72) , said slanted wall (47) being configured as a distal limit stop for the ball (72) .

14. Device according to any one of the preceding claims, further comprising a second elastic element (12)elastically connecting the knob (5) and the force application means (7a) to each other.

15. Device according to any one of the preceding claims in combination with claim 4, wherein the threaded stud (71) comprises a head (710) and wherein a recess (50) , where said head (710) is at least partially housed, is obtained in the knob (5) , the head (710) engaging the recess (50) by shape coupling so that, upon the disengagement of the annular ridge (510) from the projection (410) , the rotation of the knob (5) results in a rotation of the threaded stud (71) .

16. Device according to claims 14 and 15, wherein a housing hole (52; 712) is obtained in the head (710) and in a bottom wall (51) of the recess (50) , respectively, to accommodate the second elastic element (12) .

17. Device according to any one of the preceding claims, wherein a plurality of pins (48) is fixed to the projection (410) and on the annular ridge (510) is respectively obtained a plurality of openings (58) engageable by said plurality of pins (48) , and vice versa, the mutual engagement between the pins (48) and the respective openings (58) rotationally locking the knob (5) .

18. Device according to any one of claims 1 to 16wherein the engagement between the projection (410) and the annular ridge (510) is due to a pair of toothed ring nuts (49, 59) , where a first ring nut (49) of said pair of toothed ring nuts is fixed to the projection (410) while the second ring nut (59) is fixed to the annular ridge (510) , the mutual engagement of the pair of toothed ring nuts (49, 59) rotationally locking the knob (5) .

19. Device according to any one of the preceding claims in combination with claim 10, wherein the abutment body (6) also comprises a bottom plate (66) provided with a protrusion (67) engaging the screwing body (4) , said bottom plate (66) acting as the bottom surface of the compartment (63) where the first elastic element (73) is housed .

20. Device according to any one of the preceding claims in combination with claim 11, wherein the abutment body (6) also comprises a plurality of separation pins (68) fixed to said abutment body (6) , the separation pins (68) being configured to keep the spheres (74) angularly spaced from one other.

21. Device according to any one of the preceding claims in combination with claim 5, wherein in the screwing flange (42) is obtained at least one seat (420) facing the abutment body (6) , a third elastic element (13) being positioned in each seat (420) , so that the actuation ofthe force application means (7a) results in an axial displacement of the abutment body (6) towards the tool (2) , said axial displacement causing a compression of the third elastic element (13) , where said compression of the third elastic element (13) allows the retraction of the abutment body (6) upon the release of the preload force.

22. Device according to any one of the preceding claims in combination with claim 3, wherein the plurality of sealing elements (10) also comprises a secondary sealing element (10") , for example an elastic gasket, positioned between the screw (43) and the abutment body (6) , said secondary sealing element (10") keeping the screw (43) abutting against the screwing flange (42) .

Images