WO2005054698A1

WO2005054698A1 - Process and apparatus for the precision machining of the inner rings of bearings

Info

Publication number: WO2005054698A1
Application number: PCT/EP2003/013007
Authority: WO
Inventors: Marcus Caldana
Original assignee: Minganti S.P.A.
Priority date: 2003-11-20
Filing date: 2003-11-20
Publication date: 2005-06-16
Also published as: AU2003288130A1

Abstract

The rings (P1, P2) of the bearings are axially aligned and reciprocally secured in pairs and by the bases which face each other in the working condition, by means of a suitable adhesive (2), in such a manner to obtain a single composite workpiece (P) which in this manner may be machined with high-grade precision and with the same tolerance on the external tracks for the balls and/or onto other surfaces. Upon completion of the maching operation, the workpiece is unloaded from the machine tool and then the two rings composing the same are separated with a simple and quick operation which neutralises the action of the adhesive employed. To improve the maching of said workpiece (P) and to avoid deformations by the chuck of the machine tool, the composite workpiece (P) may be axially aligned and secured with adhesive (2’) onto a base structure (1) for a temporary support, which is grasped by the same chuck. Upon completion of the machining of the workpiece, same will be detached from said base structure.

Description

TITLE: "Process and apparatus for the precision machining of the inner rings of bearings"

DESCRIPTION The inner rings of ball bearings or of other type of bearings, are presently machined separately, with great loss of time and with great difficulty in the obtain ment of same working tolerances on the rings which are in subsequently utilised in pairs. The closest prior art known is represented by document WO 03/057392 A1. The invention intends to solve this technical problem with the following idea of solution. The inner rings of the bearings are axially aligned and reciprocally secured in pairs by the bases with which they face each other also in the working phase, by means of a suitable adhesive, in such a manner to form a single workpiece which can be easily machined with high-grade precision on the external grooves for the balls, with a single positioning onto the chuck of the machine tool. After the machining, the composite workpiece is discharged from the machine tool and then the two rings forming same are detached with a simple and quick operation which neutralises the action of the adhesive. To improve the machining of the workpiece and to avoid deformation of the same by means of the chuck of the tool machine, the said workpiece may be axially aligned and secured with adhesive onto a temporary support base structure, which is subsequently clamped by the same chuck. After the machining of the workpiece, it will be possible to detach also this latter from the said base structure. Further features of the invention, and the advantages deriving therefrom, will appear better evident from the following description of a preferred embodiment made, by way of non-limiting example, with reference to the figures of the attached sheets of drawings, in which: - Figure 1 shows laterally and with portions in section the two inner rings of a bearing secured with adhesive between them and upon a temporary support base structure with which the same rings are clamped by the chuck of a machine tool; - Figures 2, 3, 4 and 5 shows laterally and with portions in section, the steps of the reciprocal securing of the rings of the bearing. In Figure 1 , with reference P1 and P2 are indicated the two inner rings of a ball bearing which according to the invention are axially aligned between them and are reciprocally fixed with the same bases with which they face each other during the formation of the bearing, by means of a thin layer, or distributed spots, of adhesive 2 having a sufficient quick setting, for example of the adhesive commercially known with the registered trademark LOCTITE, for example of grade 380 or 480. After the setting of the adhesive, the composite unit P made by the two rings P1 and P2, may be clamped in any known way on the mandrel M of a tool machine and may be machined with precision and with the same tolerances on the external grooves which will realise the track of the balls of the bearing. The thickness created by the adhesive spots 2 is minimal, and in any case detectable with precision and the same may be considered during the planning of the working cycle of the machine tool, in such a manner that the external portions of the piece P result machined with the required precision. Referring to Figures 2 to 5 there is now described the sequence of working steps and a possible apparatus for the reciprocal securing of the rings P1 and P2. In Figure 2, reference numeral 3 indicates a vertical clamp or chuck onto which a manipulator has previously positioned for example the ring P1 which is clamped for example from the exterior and co-axially by the jaws 103 of the chuck itself and which presents its minor base upwardly directed. The chuck together with the ring P1 is carried into rotation about its axis, while a manipulator with a distributor 4 provides for the distribution, on the upper base of the ring P1 , of the adhesive spots 2. The ring P2 to be secured to the ring P1 , is taken by a gripper manipulator 5 and is positioned with its minor base onto the base of the ring P1 , provided with the adhesive spots 2. During this step the chuck 3 is for example at standstill or it is stopped. Subsequently the gripper 5 leaves the ring P2 and onto this latter there is moved and axially lowered an idle tailstock center 6, as shown in Figure 4, which has the double function of axially pressing the rings the one against the other and to precision align the same axially. During this step the chuck 3 rotates for the time which is necessary for the setting of the adhesive. Subsequently, as shown in Figure 5, the chuck 3 is stopped and the tailstock center 6 leaves the workpieces P which is clamped by the gripper 5 or another gripper and is moved away from the chuck, the jaws of which leaves free the ring P1. If the rings P1 and P2 are of large dimensions, the workpiece P formed by same may be keyed in known manner onto any chuck of a machine tool, for example onto a mechanical or magnetic grip chuck. If, on the other hand, the rings P1 and P2 are of small dimensions, the workpiece P formed by same may be advantageously pre-sticked with adhesive spots 2' and with the same technique described for the rings, on the annular projection 101 of a base structure 1 (Figure 1), which for example can be annular, of any suitable material and dimensions, the said base structure being then clamped by the jaws of the chuck M, in such a manner that the workpiece P does not result to be subjected to any deformation under the action of the chuck. The piece P clamped on the chuck may be machined with precision on the external lateral surface and, if required, also onto the other accessible surfaces for the tool U, even onto the inner surfaces. The presence of the projection 101 of the base structure 1 , permits that the piece P may be machined also on the portions near to said projection, which result suitably spaced form the underlying base structure 1. The fixing of the base structure to the workpiece P may be made by the means and with the process shown in Figures 2 to 5, starting from one of the rings P1 or P2 of from the base structure 1 , or may be made in two steps, firstly securing the rings between them, and then securing the workpiece P obtained from these to the base structure 1. The adhesive "LOCTITE" of degree 380 may be used for the securing of the piece P to the base structure 1 , while the adhesive "LOCTITE" of degree 480 may be used for the reciprocal securing of the rings P1 and P2. After the machining on the machine tool, it will be possible to detach the workpiece P from the base structure 1 with a mechanical action which breaks the lattice of the adhesive, if the same is of the 380 grade type. For this purpose, it is not excluded that that the base structure 1 may be provided with openings and/or holes which permit to suitable extractors to operate onto the base of the workpiece secured to the base structure. If instead the adhesive is of the 480 grade type, same is neutralized by means of physical heating action, for example an induction action, at a temperature of about 150° for a time period of about 20 seconds. It is to be understood that other solutions can be employed for the neutralization of the adhesive.

Claims

CLAIMS 1 ) A process for subjecting the inner rings of bearings, or other complementary workpieces, to high grade precision machining, with a single positioning onto the chuck of a machine tool, characterised by the fact that the rings (P1 , P2) are axially aligned between them and are reciprocally secured by the bases with which they face each other in the working condition, by means of a suitable adhesive (2) in such a manner to form a single composite workpiece (P) which can be clamped in any suitable manner onto the chuck of a machine tool and can be machined with great precision and with equal tolerances on its surfaces, there being provided that, after the machining, the two rings are detached by means of the neutralization of the adhesion action of the adhesive which will be selected with features so as to be neutralised with quick and easy mechanical and/or chemical and/or physical actions which do not damage the workpieces which have been machined. 2) Process according to claim 1 , in which the composite workpiece (P) made of the two rings (P1 , P2) secured between them, is, on its turn, co-axially positioned with its base on a base structure (1 ) upon which it is fixed, with suitable adhesive (2'), in such a manner that the workpiece may subsequently positioned on the chuck of the machine tool by clamping the said base structure (1 ), while the composite workpiece may be machined on the external and/or inner surfaces with a single positioning and with high precision, there being provided that after the machining, the piece is detached from the base structure with the neutralization of the securing action of the adhesive. 3) Process according to claim 1 , in which the adhesive is distributed by spots (2, 2') suitably located along the surface of the base structure (1 ) which supports the workpiece (P) to be machined or on the base of the ring (P1) which supports the complementary ring (P2). 4) Process according to claim 3, in which the adhesive spots (2, 2') are distributed on the surface of the base structure (1 ) or on the base of the ring (P1 ) which must support the complementary ring (P2), which are upwardly directed, which are horizontally arranged and which preferably rotate upon command around their vertical axis. 5) Process according to claim 4, in which on the upwardly directed surface of the ring (P1) or of the base structure (1), provided with the adhesive spots (2, 2') there is co-axially positioned the workpiece to be fixed (P, P2), which is axially aligned and is pressed downwardly for the time required for the solidification and the setting of the adhesive, after which the unit formed by the two rings (P1 , P2), or of the rings with the base structure, can be transferred to the working cycle of the same rings to the machine tool. 6) Process according to claim 2 in which the base structure (1) presents a cylindrical and annular shape. 7) Process according to claim 2, in which the base structure (1) is coaxially provided with an annular projection (101 ) or with an equivalent projecting portion, onto which there can rest one base of the workpiece (P) to be machined which therefore results suitably spaced from the said base structure, thus favouring the correct machining by the tools also of the parts of the workpiece which are near to the supporting base structure. 8) Process according to claim 1 , in which the employed adhesive is of the type known by the registered trademark LOCTITE, for example of grade 380. 9) Process according to claim 1 , in which the employed adhesive is of the type known by the registered trademark LOCTITE, for example of grade 480. 10) Process according to claim 8, in which the adhesive can be neutralized by means of a mechanical action exerted on the workpieces and/or on the base structure supporting same. 11 ) Process according to claim 9, in which the adhesive can be neutralized by means of a heating operation at a correct value of temperature. 12) Apparatus for subjecting composite workpieces having annular shape, consisting for example of the two facing inner rings of a bearing, to high-grade precision machining on the outer and/or inner surfaces, with a single positioning onto the chuck of a machine tool, characterised by comprising means for securing with adhesive the rings (P1 , P2) to be machined and if required to secure with adhesive the composite workpiece (P) made by the same rings, on a temporary support base structure (1), the whole in such a manner that the several portions result to perfectly aligned between them in axial direction and comprising means which, once the composite workpiece (P) is machined, provide to detach same from the base structure and to reciprocally detach the rings which form the said workpiece. 13) Apparatus according to claim 12), in which the means for securing with adhesive a ring (P1) to the other ring (P2), or the workpiece (P) made by the same rings on the base structure (1), comprise:

- a clamp or chuck (3) having a vertical axis and directed upwardly, - a manipulator with self-centring clamping means (5) which, upon control, positions the base structure (1) or one ring (P1) coaxially onto said chuck (3) which clamps and axially centres same,

- means for positioning above the projection (101) of the base structure or above the upper base of the ring (P1 ), a device (4) which upon control distributes an adhesive onto said projection or onto said base, while the chuck with the base structure or with the ring is rotated about its axis,

- a manipulator with a jaw (5) for coaxially positioning the second ring (P2) onto the first or for positioning the workpiece (P) onto the projection (101) of the structure base, - a manipulator with a self-centring center (6) which is axially pushed onto the second ring (P2) or onto the workpiece (P), while the whole is preferably caused to rotate by the chuck which is supporting the portions to be secured, there being provided that, once the adhesive has set, suitable means provide to discharge from the chuck (3) the reciprocally secured portions, to arrange the same chuck for a new working cycle. 14) Apparatus according to claim 12 characterized by the fact that the adhesive used is "LOCTITE" of grade 380, and the reciprocal detachment of the rings and/or the detachment of the same from the base structure is obtained by means of a mechanical action, for example by impact, by vibration or by thrusts or pressure for detachment, exerted between the surfaces to be detached. 15) Apparatus according to claim 14, in which the base structure (1 ) may be provided with openings or holes for consenting the intervention of extractors for the detachment of the workpiece glued onto the said base structure. 16) Apparatus according to claim 21 , characterised by the fact that the adhesive used is "LOCTITE" of grade 480, and the reciprocal detachment of the rings and/or the detachment of these from the base structure is obtained by subjecting the workpieces to heating by induction means, for reaching a temperature of about 150° C and for a time period of about 20 seconds.