DESCRIPTION Pair of pincers for mounting reaming tools.
Technical field
The invention relates to a pair of pincers for mounting reaming tools.
Background Art As it is known, reaming machines are operating machines called upon to perform the function of providing the exact internal diameter, established during the design phase, of a hole machined in a metal mass; this function, which in reality is the internal grinding of the said hole, is carried out using reaming tools. During the processing phase, the said reaming tools are applied to the head of a reaming machine by means of locking pincers, mounted in their turn to suitable pincer holders which can have either a cylindrical shank or a Morse tapered shank. The pair of pincers must possess a certain potential for self-adjustment in relation to the said hole, so as to automatically adjust to the said hole already machined using other processes and other tools, said self- adjustment being designed to prevent the deformation of the hole to be reamed; it being possible for the said self-adjustment to take the form of either an angular shift or a lateral shift of the reaming tool in relation to its longitudinal axis.
This self-adjustment potential of the reaming tools becomes extremely important as far as the repetitiveness of the reaming precision on a single hole is concerned. The said self-adjustment action has been obtained for some time, and occurs, substantially, by means of the slight radial gap that exists between an internal body and an external body of which the aforesaid pincers are constituted.
At this point it is important to note that on certain reaming machines, such as, for example, on work stations or on numerically controlled lathes in which the aforesaid pincer holders are fitted on motorised heads, the space around the area concerned by the processing and, therefore by the reaming tools, is exiguous in comparison with the considerable size of the pincer
holders; the resulting drawback is that there are numerous difficulties regarding the operational ability of the reaming tools and, in some cases even, their inability to operate if the pieces to be reamed have particular dimensions or the reaming to be carried out is particularly deep and therefore the aforesaid tools must be extremely long.
Furthermore, as with the reaming tools it is the case that the smaller diameter the greater need for self-centring/self-shifting and vice versa, inside the pair of pincers of a commonly-known kind there is generally a regulation system provided for self-adjustment purposes; this fact leads to the drawback that the construction of the pair of pincers is increasingly complex, and there is consequently greater probability of the said pair of pincers malfV ctioning and they cost more.
A further drawback of the commonly-known kind of pincers is constituted of the fact that extraneous elements, in particular working shavings, can penetrate the pair of pincers, even causing breakage, and this can be even more detrimental if one considers, as just mentioned, the presence of a regulation system for self-adjustment inside the said pair of pincers. Disclosure of Invention A first aim of this invention is the realisation of an innovative motion transmission system between the parts constituting the pair of pincers together with the reaming tools' self-adjustment capacity. A further aim consists in the realisation of a pair of pincers without internal regulation systems for self-adjustment. A third aim consists in the realisation of an impediment, inside the pair of pincers, to the penetration of dirt and metal shavings among the parts constituting the said pair of pincers.
A still further aim of this invention consists in the realisation of a pair of pincers for reaming tools which are compact and, contemporaneously, capable of achieving, at the least, the aims just stated in order to ensure an increased operative flexibility during reaming operations on any typology of operating machines designed to perform a reaming action. In particular, the pair of pincers for reaming tools in question in this invention are of the kind consisting of at least one internal hollow cylindrical body inside which the shank of the said tool can be fixed, and one external body, the said two bodies being reciprocally coaxial, characterised by a plurality of spheres is interposed between the said internal and external bodies and by the fact that at least two elastic elements are also interposed between the two said internal and external
bodies; the said plurality of spheres being designed both to transmit the rotary motion of a pincer holder from the external body to the internal body and to permit the self-adjustment of the reaming tool to fit the hole to be reamed; the said at least two elastic elements being designed to both centre the internal body and prevent dirt and shavings entering the gap between the internal body and the external body and also to dampen the said self-adjustment action.
These and other characteristics will better emerge in the description that follows of a preferred embodiment illustrated, purely in the form of a non- limiting example, in the plates enclosed, in which: - figure 1 shows an overview of the pair of pincers fitted with a reaming tool; - figure 2 shows a partial section of the contents of the previous figure without the reaming tool; - figure 3 shows a longitudinal section of the internal body of the pair of pincers shown in figure 1; - figure 4 shows a longitudinal section of the external body of the pair of pincers shown in figure 1.
With reference to the figures, 1 is a pair of pincers for a reaming tool 2; the said pair of pincers are composed of an internal body 3 and an external body 4, both of which are reciprocally coaxial to a longitudinal axis A-A and both to a revolution surface.
On the external surface of the internal body 3 there are four seats 5 machined with substantially semicircular concavities with diameters substantially equal to the diameter of the spheres 6. Also on the external surface of the internal body 3 there are two first circumferential grooves 7 machined, which are designed to hold an elastic element 8, for example an O-ring.
On the surface of the external body 4 there are four channels 9 which extend parallel with the axis A-A; each of the said channels having a width which is substantially equal to the diameter of each of the spheres 6.
10 is a second circumferential groove deigned to hold an elastic locking element 11, for example, a Seger ring, the said groove being positioned at one end 12 of the internal body 3. In proximity to a second end 13 of the internal body 3, mere are four threaded holes 14 machined; 15 indicates the four locking elements, for example threaded dowels. The internal body 3 is axially hollow due to the presence of a first
cylindrical cavity 16, coaxial to the axis A-A and extending along the entire length of the said internal body.
The external body 4 is axially hollow due to the presence of a second cylindrical cavity 17 coaxial to the axis A-A and extending along the entire length of the said external body; said external body has a third circumferential groove 18 machined on it externally. There will now follow a description of the functioning of this invention, using the references indicated in the figures. After inserting the shank of the reaming tool 2 into the first cavity 16 and after locking it inside the internal body 3 by means of the locking elements 15, work can be begun by rotating the pincer holder, not shown; the rotation of the latter is transmitted to the pincer 1 thanks to the tapered connection between the said pair of pincers and the respective pincer holder. The rotary motion of the pair of pincers 1 is transmitted from the external body 4 to the internal body 3 by means of the action by which the spheres are interposed between the said two bodies. It should be noted that the use of the said spheres also permits a greater reciprocal articulation capacity between the internal body 3 and the external body 4. The internal body 3 and the external body 4 are reciprocally centred thanks to the presence of the elastic elements 8; however, when the reaming tool 2 begins to engage with the hole to be reamed it can adjust itself to fit the said hole perfectly thanks to the gap between the two bodies 3 and 4, thanks to the shifting freedom allowed by the gap between the spheres and their respective seats 5 and the chamiels 9 and thanks to the elastic yieldingness of the elements 8.
The self-adjustment of the reaming tool 2 is performed, as mentioned earlier, in two ways: an angular shifting in relation to the longitudinal axis A-A of the pair of pincers 1 and a lateral shifting of the entire tool in relation to the said axis. In both cases not only is the gap between the internal body 3 and the external body 4 exploited, which, in the commonly known embodiments, reaches values of around 0.5 mm, but also the greater articulation capacity between the aforesaid two bodies, thanks to the presence of the spheres 6, as already highlighted earlier. The presence of the two elastic elements 8, also ensures any dirt, particularly metal shavings, is prevented from entering the gap between the two bodies 3 and 4: in fact each of the two elastic elements, when the pair of pincers 1 are fitted, is pressed between the respective
circumferential groove 7 and the internal surface of the external body 4, thus obtaining a closing action as regards the gap between the two bodies 3 and 4. Considering the size of the said gap, which, let us repeat, is about 0.5mm, the said closing action performed by the said two elastic elements is however still guaranteed even in the presence of the greater angular shifting and the greater reciprocal lateral shifting possible at the two bodies 3 and 4.
A still further possible embodiment, not shown, envisages the presence of a plurality of channels, all machined on the external surface of the internal body 3 parallel with the longitudinal axis A-A and extending along the entire length of the said internal body.
The presence of the said channels permits the passage of liquid coolant from the pincer holder to the cutting portion of the reaming tool 2, slamming the entire external surface of the shank of the said tool in the event that the machine tools are fitted with working heads equipped for the adduction of the said liquid axially in relation to longitudinal axis of the said tool corresponding to the longitudinal axis A-A of the pair of pincers 1. The presence of the said channels permits the liquid coolant to overcome the barrier constituted of the elastic elements 8 while not impairing the seal against dirt ensured by the said elements: in fact, in the area corresponding to the said longitudinal channels, the dirt cannot penetrate the channels because of the liquid coolant flowing in the opposite direction. The said longitudinal channels can be machined, instead of on the external surface of the internal body 3, on the internal surface of the external body 4.
Note that the description of this invention refers in particular to a pair of pincers referable to the ER typology (DLN6499/B). Tests carried out by the applicant would seem to demonstrate that the measurements of both the gap between the two bodies 3 and 4 and the distance between the two elastic elements 8 would maintain substantially the same proportionality in relation to the external diameter of the internal body 3 regardless of any variations in the latter with respect to variations in the size of the pair of pincers 1, with respect - in their turn - to the variable size of the reaming tool 2.
Throughout the description, explicit references have been made to the reaming operation, but obviously, this invention could also be used advantageously as a support for other tools designed to work with the
removal of shavings of different kinds, for example, the rigid tapping that is currently performed on numerically controlled operating machines. Throughout the description, explicit references have also been made to the fact that the pincers subject matter of the present invention is referable to ER typology (DIN6499/B) pincers, but obviously the teaching of this invention is also advantageously applicable to different typologies of pincers and clamps.
A first advantage of this invention obtained by means of the pair of pincers in question in the present invention consists in the fact that the presence of the said spheres between the two bodies forming the said pair of pincers permits the transmission of the rotary motion together with a greater reciprocal articulation capacity between the said two bodies.
A second advantage consists in the fact that the pair of pincers subject matter of the present invention do not have internal systems designed for the self-adjustment of the position of the reaming tool in the hole to be reamed. A third advantage consists in the presence of the elements designed to prevent dirt in general, and metal shavings in particular, entering the gap between the two bodies constituting the pair of pincers. A still further advantage is represented by the possibility of the realization of a pair of pincers that, although compact, include features capable of furnisliing, at the least, the advantages shown above.