TOOL COLLET SPINDLE LOCKING SYSTEM

Abstract: A locking system for the spindle supporting the tool collet of machine tools, comprising a chamber (8) filled with a medium adapted to apply a compressive force on the spindle (1-3) so as to lock it around the collet, through a mechanical control member (11-13) which can be manually actuated without physical effort, the system comprising also a device (17-20) for positioning the collet or the tool inside said collet.

Description: "TOOL COLLET SPINDLE LOCKING SYSTEM" The present invention relates to a locking system for the spindle supporting the tool collet of machine tools, allowing to apply considerable locking forces with a minimal effort by operator and therefore is a considerable technical development in comparison with the presently used systems. It is known that the tool locking collets must be introduced in the corresponding spindle seat and are blocked therein by mechanical systems requiring a great effort by operator and subject to great mechanical strains, so that they undergo wear and all the mechanical drawbacks normally occurring to severely strained parts. The system according to the present invention is based on the innovative principle of providing in the spindle housing a chamber filled with a medium adapted to apply a compressive force on the spindle, the inner body of which has the form of a double or single splined cone, so as to lock it around the collet, the compressive force of the medium being regulated through a mechanical control member which can be manually actuated by the operator without physical effort. The system according to the present iivention comprises also a device for positioning the collet or the tool inside the collet, which can also be actuated by the operator without physical effort and acting on the spindle positioning piston. The characteristics, objects and advantages of the system according to the present invention will be also apparent from the following detailed description of a preferred embodiment, which is given as a non limiting example of the scope of the invention, reference being had to the accompanying sheet of illustrative drawing, whose single 5 figure is a sectional elevational view of a spindle provided with the locking system of the present invention. With reference now to the accompanying drawing, the spindle to be provided with the system of the present invention may be of any conventional type, and therefore its housing 1 may comprise at its upper end an adaptor 2 of any size and shape, such as an 0 ISO, Morse taper cone, cylindrical adaptor and so forth. The housing 1 comprises at its lower end a wide cavity in which there is the inner body 3 of the spindle, so as to lock in the central seat 4 the collet (not shown) which may also be of any size and shape, such as round, square, polygonal, said collet supporting in its turn the tool, which may also be of any conventional size and type. *-* The inner body 3 of the spindle is being shown in the annexed drawing in the form of a double convex cone, but it could also be a double concave cone or even a single concave or conve cone, and is provided with alternate slots for its compression. The inner body 3 is being held at the lower end by a fixing ring nut 5 and at the upper end by a closure thrust bearing block 6. ® Above this group there is the thrust bearing ring 7 enclosing the plenum chamber 8 with inner and outer sealing O-Rings 9 and 10, respectively. The plenum chamber 8 is filled with a medium adapted to apply a compressive force on the inner body 3 of the spindle through the thrust bearing members 7 and 6. Such a medium is generally an incompressible fluid such as oil, but it could be any other material, e.g. micropellets. t ^ The pressure of such a medium may be regulated through a little piston 11, inserted in the bushing 12 screwed inside the housing 1, said piston 11 being actuated by the screw 13 on which one can operate from outside with a suitable tool, without any particular effort of the operator. It is therefore clear that by tightening the screw 13 one increases the pressure on the spindle body 3 which consequently locks the collet, while by loosening the screw 13 the collet is unlocked. The connection between piston 11 and plenum chamber 8 is effected through a communication hole 14 which may be arranged in any suitable position, as well as the bleed valve 15 normally provided in any pressurized system. It is to be particularly pointed out that this locking system might also be arranged 0 in other positions inside the spindle housing and therefore said system could be arranged aside the spindle inner body or under it, instead above it as shown in the illustrative drawing for the preferred embodiment of the invention. Such a system may apply a substantial locking force, e.g. of 6-10 tons or even more. The system of the present invention may also provide for a positioning device for 5 the collet or preferably for the tool arranged inside the collet. This occurs by moving downwardly the piston 16 for positioning the spindle (which has a central projection not visible in the figure, pushing just on the tool bottom) through a recessed central screw 17, which can also be operated without physical effort by a suitable tool, actuating a wedge 18, in turn pushing downwardly the inclined plane 19 and therefore " the piston 16, which is urged back upwardly by the return spring 20. It is clear that this mechanism with inclined plane might be replaced by other equivalent devices, such as a worm gear and level gears, clearly without departing from the scope of the invention, or it could be an oil hydraulic control of the same kind of that devised for locking the collet. 5 From the foregoing description it can be easily understood that the system of the present invention completely fulfils the stated objects and gives considerable advan¬ tages in locking a tool in the corresponding collet of the spindle, but it has to be understood that several modifications, variations, additions and/or substitutions of elements and details may be resorted to the system of the present invention, without departing however from its spirit and object, and without falling outside its scope of protection, as it is also defined in the appended claims.

Claims: 6 . CLAIMS 1) Locking system for the spindle supporting the tool collet characterized by the fact of comprising in the spindle housing (1) a chamber (8) filled with a medium adapted to apply a compressive force on the spindle (1), the inner body (3) of which has the form of a double or single splined cone, so as to lock it around the collet, the compressive force of the medium being regulated through a mechanical control member which can be manually actuated by the operator without any physical effort. 2) Locking system according to Claim 1, characterized by the fact that the pressure medium is an incompressible fluid such as oil. 3) Locking system according to Claim 1, characterized by the fact that the pressure medium is a loose material such as micropellets. 4) Loocking system according to Claim 1, characterized by the fact that the plenum chamber (8) acts on the spindle inner body (3) through a thrust bearing ring nut (5) and a closure thrust block member (6). 5) Locking system according to Claim 1, characterized by the fact that the plenum chamber (8) is provided with a bleed valve (15). 6) Locking system according to Claim 1, characterized by the fact that the pressure regulation in the plenum chamber (8) is effected through a little piston (11) connected with said chamber (8), the piston being (11) actuated by a screw (13) which can be manually operated from outside the housing (1) without any physical effort of the operator, by means of a simple suitable tool. 7) Locking system according to Claim 1, characterized by the fact that the plenum chamber (8) may be arranged above, aside or under the spindle inner body (3). 8) Locking system according to one or more of the preceding claims, characterized by the fact of further comprising a device for controlling the tool position inside the collet or the position of said collet, said device acting on the spindle positioning piston (16). 9) Locking system according to Claim 8, characterized by the fact that said position controlling device comprises a screw (17) which can be manually operated 5 from outside without operator's effort, acting on a system of inclined plane, wedges (18) or other mechanical equivalent members, in order to move downwardly the spindle positioning piston (16), which is urged upwardly by a return spring (20). 10) Locking system according to Claim 8, characterized by the fact that said position controlling device comprises a worm gear and a pair of bevel gears, which can ° . be actuated by the operator. 11) Locking system according to Claim 8, characterized by the fact that said position controlling device is an oil hydraulic device having structure and function similar to those of the main device for locking the collet. 12) Locking system for the spindle supporting the tool collet; substantially as hereinbefore described and as illustrated in the accompanying drawing, for the above mentioned objects.

Inventors: MOLTENI CORNELIO, MOLTENI, CORNELIO
Applicants: MOLTENI CORNELIO, MOLTENI, CORNELIO
Application year: 1985
Main classification: B23B31
IPC codes: B23B31