LAPPING-MACHINE, ESPECIALLY FOR FINE SURFACE-MACHINING OF BEARING BALLS

Description

[0001] The invention relates to a lapping machine according to the introductory part of claim 1.

[0002] Generally, lapping machines for machining bearing balls may be classified in two main groups; namely those comprising machining disks and ball magazines with horizontal axes, and those with vertical axes.

[0003] Practical experiences have shown that with the vertical axis arrangement far better machining quality can be achieved than with the horizontally arranged axes.

[0004] Several equipments with machining disks with vertical axis are known, and here, the best ball machining quality can be attained with machines provided with annular ball magazines having a vertical axis and surrounding the machining disks. The known machines, however, often suffer from the drawback that oscillations are transferred to the machining disks during the machining so that satisfactory machining quality cannot be achieved. Furthermore, the structural design and dimensions, or dimensional ratios, respectively, of the machining disks sometimes do not enable identical rolling-down and adequate machining conditions, and the charge and discharge of the balls to be processed is often accompanied by the fact that the balls are heaped up and held back, with the consequence that the balls may be damaged.

[0005] AT-B-303 560 discloses a lapping machine with the features of the introductory part of the main claim. At this known machine, both the common central axis of the machining disks and the axis of rotation of the ball magazine are vertical, and in an attempt to avoid damages in course of introduction and removal of the balls, the centre of compressive force acting on the machining disks is arranged behind the centre of gravity so that at the points of introduction and discharge of the balls, the compressive force is decreased. Furthermore, to assist the introduction of the balls into the grooves, a vibrator is used at the point of introduction. Nevertheless, it is not possible to ensure the undisturbed and uniform charge of the balls between the machining disks. On the other hand, at the point of discharge, it cannot be avoided that the balls heap up to the level of the balls in the ball magazine. In such a manner the weight of the heaped up balls hinders the egress of the balls from the space between the disks.

[0006] From DE-C-964 028 it is known at lapping machines to promote charging and discharging of balls by inclining the machining disks up to 90° with respect to the ball magazine. At this known machine, however, the common system consisting of the machining disks and the ball magazine is not at all taken into consideration so that during operation the disks are excessively worn, the height of the disks being reduced, so that the machining disks will become misaligned with respect to the ball magazine. Consequently, the gravitational charging and discharging of the balls is affected, and the balls may be damaged.

[0007] The main object of the present invention is to provide a lapping machine of the type as defined in the introductory part of the main claim which eliminates the drawbacks of the machines known up to now and moves the whole charge of the pre-processed balls during the machining under optimal conditions of circulation and delivery and ensures a high accuracy with respect to dimensions and geometry as well as high surfacial accuracy of the processed balls. Furthermore, an accurate and oscillation-free rotation of the main spindle and of the lower machining disk is intended in connection with a stiff guiding of the upper machining disk, with the possibility of continuous regulation of the pressure acting between the machining disks, and of the speed of rotation of the ball magazine without the necessity of stopping the machine, and with the possible speed change of the main spindle.

[0008] Accordingly, the present invention provides a lapping machine of the type referred to above, which is characterized by the features as defined in the main claim.

[0009] Preferred embodiments are characterized in the attached sub-claims.

[0010] The invention will be described now in greater detail by way of example with reference to the accompanying drawings, in which:

Fig. 1 shows a top view of a lapping machine according to the invention;

fig. 2 is an elevation view of the machine according to fig. 1, shown in a longitudinal section taken along the line A-D of fig. 1;

fig. 3 shows the position of the machining disks of this machine relative to the ball magazine in a sectional view;

fig. 4 shows a top view of a part of the machining disks according to fig. 3 together with the elements leading in and out the balls;

fig. 4a shows a sectional view taken along the line A-A of fig. 4;

fig. 4b shows a sectional view taken along the line B-B of fig. 4;

fig. 4c shows a sectional view of the machining disks taken along the line C-C of fig. 4; and

fig. 5 shows a sectional view similar to fig. 3, to illustrate another possible relative position of the machining disks and of the ball magazine.

[0011] Fig. 1 and 2 illustrate the relative position of the machining disks 1, 2 (which in fig. 1 are covered by a clamping hub 22, see fig. 2, and which are clamped together by means of a nut 21) and a ball magazine 3 surrounding the machining disks 1, 2, as well as the form and arrangement of the ball leading elements which in their design essentially correspond to the design of the ball leading elements applied on known machines. Guide rods 5 assure stiff guiding of the upper machining disk 1. An extension of the upper machining disk 1 on the side opposite to the ball leading elements is connected to a hydraulic lifting unit 19 for the adjustment in height of the upper machining disk 1.

[0012] Motion conditions of the shown ball lapping machine in course of processing balls 39 can be well followed by the aid of the arrows; so e.g. arrow 36 in fig. 1 refers to the direction of rotation of the ball magazine 3 when transferring the balls 39 to be lapped in direction of the arrow 37 between grooves 27 of the machining disks 1, 2 (by means of the ball leading elements as shown in fig. 1) where actual machining of the balls 39 is taking place. In course of processing, the lower machining disk 2 rotates in direction of arrow 35, and as a consequence of this rotary motion, the balls 39 already processed in the grooves 27 of the machining disks 1, 2 are discharged along the ball leading elements into the ball magazine 3 as indicated by arrow 38. This "migration" of the balls as described above is repeated several times in course of a machining cycle.

[0013] According to figs. 2 and 3, the ball magazine 3 has a vertical axis 33 of rotation, whereas the machining disks 1, 2 have a common central axis 32 which encloses an angle α with the vertical. The upper machining disk 1 is arranged on the clamping hub 22, while the lower rotating machining disk 2 is arranged on a main spindle 6 driven by a change pole motor 30 through a drive 9 and a speed reducing and relieved transmission consisting of a V-belt 24 and a V-belt pulley 25. The guide rods 5 are arranged in parallel with the axis of the main spindle 6 which is identical with the common axis 32 of the machining disks 1, 2, and thus may assure stiff guide of the upper machining disk 1. The upper machining disk 1 and the lower machining disk 2 are fastened together with the balls 39 inserted therebetween by a draw spindle 20 connected to a hydraulic cylinder 8 and by the nut 21 provided with a Belleville spring 29.

[0014] The clamping hub 22 of the upper machining disk 1 is further provided with the hydraulic lifting unit 19 which on the one hand serves to establish the difference in height of the machining disks 1 and 2, and on the other hand facilitates exchange of the disks 1, 2.

[0015] The ball magazine 3, i.e. its rotary part, is driven by means of a hydraulic drive 18 with continuously variable speed, preferably a worm drive, through a connecting rod 17 with cardan joints, a spur gear 16 connected to the connecting rod 17, and a gear rim 26 arranged below the rotary part of the ball magazine 3. A bearing 23 takes up the radial and axial loading of the rotating ball magazine 3 with respect to a stationary part 4 of said ball magazine 3.

[0016] A gear 11 which is driven by an electromotor 10 is arranged to drive a gear rim 12 to form a speed reducing transmission which further comprises e.g. three spur gears 13 rotated by the gear rim 12 and each provided with a threaded bore, preferably with a trapezoidal thread; then to support the lower stationary part 4 of the ball magazine 3, and to rise or lower it in the direction of the main spindle 6, the machine is provided with e.g. three threaded spindles 14, preferably trapezoidal threaded spindles, performing an axial motion in the spur gears 13 and connected to supports 15 which in turn are connected to the lower stationary part 4 of the ball magazine 3.

[0017] In the present embodiment, the machining disks 1, 2 are positioned so that their common axis 32 enclosing the angle α with the vertical intersects with the vertical axis 33 of the ball magazine 3 in the bottom plane 34 of the ball magazine 3, i.e. in the plane of the bottom plate of the rotary part of the magazine 3, as is shown in fig. 3.

[0018] Fig. 3 shows in detail the relative position of the machining disks 1, 2 and of the ball magazine 3, and it may be seen that in course of processing, the balls 39 are rolled between the grooves 27 of the machining disks 1, 2.

[0019] Fig. 4 illustrates the relative position of the machining disks 1, 2 according to fig. 3 and the ball magazine 4 in a top view. Again, the arrows 35-38 in fig. 4 indicate motion conditions in course of processing in compliance with fig. 1.

[0020] Figs. 4a, 4b and 4c illustrate more in detail the ball stream conditions during the processing.

[0021] Fig. 4b shows the instream (charging) of the balls 39 from the ball magazine 3 into the gap between the machining disks 1, 2, while fig. 4a illustrates the outstream (discharge) of the balls 39 from that gap.

[0022] As it may be seen from figs. 4a to 4c, balls 39 are instreaming below the plane 34 of the bottom plate of the ball magazine 3, while they are discharged above said plane 34; accordingly, the instream and outstream of the balls 39 is taking place merely by gravitation, and therefore damages and retention of the balls on heaping up are avoided.

[0023] It should be mentioned that the elements leading in and out the balls 39 are essentially identical with the elements as used at known machines, the only difference referring to their position, dimensions and shape which are in compliance with the machining disks 1, 2 of the present machine.

[0024] Fig. 5 illustrates the relative position of the machining disks 1, 2 and of the ball magazine 3 in a further embodiment of the invention. Here, the common axis 32 of the machining disks 1, 2 is vertical, and the axis 33 of the ball magazine 3 encloses an angle α with the vertical. The common vertical axis 32 of the machining disks 1, 2 intersects the axis 33 of the ball magazine 3 in the plane 34 of the bottom plate of the ball magazine 3. It should be noted that by a slight modification of the position of the elements leading in and out the balls 39, the point of intersection of the axes 32 and 33 may also lie above or below the plane 34 of the bottom plate 34 of the ball magazine 3.

[0025] The lapping machine according to the invention operates as follows:

[0026] In all cases, the cycle of processing starts with filling up the ball magazine 3; the quantity of the balls 39 corrresponds to one charge of processing. Thereafter, the drive 18 is actuated to rotate the rotary part of the ball magazine 3 through the connecting rod 17 with the cardan joints, the spur gear 16 attached to the connecting rod 17, as well as through the gear rim 26 connected to the bottom part of the ball magazine 3. Now the main spindle 6 is put into rotary motion, which is essentially performed by switching-on the change pole motor 30 so that, through the drive 9, the V-belt 24 connected to the drive 9 and the relieved V-belt pulley 25, the main spindle 6 and therewith the machining disk 2 is rotated. With the minimum pressure prevailing in the hydraulic cylinder 8, the connection between the machining disks 1 and 2 needed for processing is established by the aid of the draw spindle 20 and the nut 21 provided with the Belleville spring 29. Then, the cycle of machining may begin.

[0027] In order to obtain proper circulation of the balls 39 and adequate flow of the cooling lubricating liquid needed for processing, the pressure of the hydraulic cylinder 8 is set to the desired value and regulated as required during operation. After having finished the cycle of processing, the balls are removed.

[0028] In the case that the height of the machining disk 2 made of cast iron changes, e.g. due to wear, the height of the ball magazine 3 is to be adjusted accordingly. This adjustment in height is performed by starting the electromotor 10, to rotate the gear 11, the gear rim 12, and the gear 13, to actuate the threaded spindle 14 and displace the support 15.

[0029] In the course of an adjustment, or of an exchange of the machining disks 1 and 2, the upper machining disk 1 can be lifted with the clamping hub 22 by means of the hydraulic lifting unit 19. Pressure changes at the machining disks 1, 2 resulting from machining and external pulses, or oscillations in course of processing may be compensated by the Belleville spring 29 forming the element of the construction fastening together the machining disks 1 and 2.

[0030] The described manner of driving the main spindle 6 provides the possibility for machining balls 39 with smaller or larger dimensions with different speed of rotation of the disk 2 in accordance with the prevailing ball sizes.

[0031] It should be mentioned that e.g. instead of the specified mechanical elements of the drive means, any other driving means may be applied provided that these are equally suitable. For instance, if driving of the structural elements and machining can be assured, electric drive elements can be used throughout, and the whole machine can be completely automatized. In this case, the whole machine should be provided with known elements required for automatization.

[0032] The advantages of the lapping machine as described are as follows:

• equal flow of the balls can be achieved during the complete cylce of machining, and charging and discharging of the balls into and out from between the machining disks can be achieved gravitationally, free of turbulence, thereby avoiding any damages, so that the extent of waste can be reduced to the minimum;
• precise bearing support of the lower machining disk, oscillation free drive, and accurate and stiff guide of the upper machining disk enable optimal conditions for the production of balls in the prescribed quality and true to shape.

Claims

1. Lapping machine for machining balls (39), in particular for fine surface machining of bearing balls, said lapping machine comprising: two coaxially arranged machining disks (1, 2) in superimposed relationship and having a common central axis (32) as well as coaxial grooves (27) in their faces facing each other, said grooves (27) cooperating in pairs to receive the balls (39); a rotatable ball magazine (3) surrounding the machining disks (1, 2), ball leading means being associated therewith for leading the balls (39) into and out of said grooves (27); a main spindle (6) coupled to a drive motor (30) for driving the lower one of the machining disks (2), the upper one (1) being stationary during operation and including a recess for cooperation with said ball leading means; means including a pressure cylinder (8) for applying a pressure onto the upper machining disk (1) with respect to the lower machining disk (2) during operation; and driving means (16-18, 26) for rotating said ball magazine (3) with respect to said machining disks (1, 2), characterized in that the axis of rotation (33) of said ball magazine (3) and the common central axis (32) of said machining disks (1, 2) are inclined with respect to each other to include an angle (α); in that guide rods (5) are arranged in parallel relationship with respect to said common central axis (32) of said machining disks (1, 2) for rigidly guiding the upper machining disk (1); in that the ball magazine (3) comprises a stationary part (4) mounting the rotary part of the ball magazine (3); and in that a spindle mechanism (11-14) is connected to the stationary part (4) of the ball magazine (3) for displacing said ball magazine (3) in the direction of the central axis (32) of the machining disks (1, 2).

2. Lapping machine according to claim 1, characterized in that the axis of rotation (33) of the ball magazine (3) is inclined with respect to the vertical, the common central axis (32) of said machining disks (1, 2) extending vertically.

3. Lapping machine according to claim 1 or 2, characterized in that the spindle mechanism (11-14) for displacing said ball magazine (3) comprises a gear rim (12) driven by an electromotor (10) and meshing with a spur gear (13) which has a threaded bore receiving a threaded end of the spindle (14), the other end of said spindle (14) being connected to the stationary part (4) of the ball magazine (3).

4. Lapping machine according to anyone of claims 1 to 3, characterized in that said driving means (16-18, 26) for rotating the rotary part of said ball magazine (3) comprises a continuously adjustable hydraulic drive (18) as well as a connecting rod (17) coupled therewith and carrying a spur gear (16) which meshes with a gear rim (26) on the rotary part of the ball magazine (3).

5. Lapping machine according to claim 4, characterized in that the connecting rod (17) is provided with cardan joints.

6. Lapping machine according to anyone of claims 1 to 5, characterized in that the point of introduction of the balls (39) into the grooves (27) of the machining disks (1, 2) is lower than the plane of the bottom (34) of the ball magazine (3) whereas the point of discharge of the balls (39) is higher than the plane of the ball magazine bottom (34).

7. Lapping machine according to anyone of claims 1 to 6, characterized in that the drive motor (30) for rotating the lower machining disk (2) is a change pole motor (30) to which the spindle (6) is coupled through a speed reducing and relieved transmission (24, 25).

Ansprüche

1. Läppmaschine zum Bearbeiten von Kugeln (39), insbesondere zur feinen Oberflächenbearbeitung von Lagerkugeln, mit: zwei übereinander vorgesehenen, koaxial angeordneten Bearbeitungsscheiben (1, 2), die eine gemeinsame zentrale Achse (32) sowie koaxiale Nuten (27) in ihren einander zugewandten Flächen aufweisen, wobei die Nuten (27) paarweise zusammenarbeiten, um die Kugeln (39) aufzunehmen; einem drehbaren Kugelmagazin (3), das die Bearbeitungsscheiben (1, 2) umgibt, wobei Kugelführungsmittel zugeordnet sind, um die Kugeln (39) in die und aus den Nuten (27) zu führen; einer Hauptspindel (6), die mit einem Antriebsmotor (30) gekuppelt ist, um die untere der Bearbeitungsscheiben (2) anzutreiben, wobei die obere (1) im Betrieb stationär ist und eine Ausnehmung zum Zusammenarbeiten mit den Kugelführungsmitteln enthält; Mitteln, die einen Druckzylinder (8) enthalten, um im Betrieb einen Druck auf die obere Bearbeitungsscheibe (1) relativ zur unteren Bearbeitungsscheibe (2) aufzubringen; und Antriebsmitteln (16-18, 26) zum Drehen des Kugelmagazins (3) relativ zu den Bearbeitungsscheiben (1, 2), dadurch gekennzeichnet, daß die Drehachse (33) des Kugelmagazins (3) und die gemeinsame zentrale Achse (33) der Bearbeitungsscheiben (1, 2) relativ zueinander geneigt sind, um einen Winkel (α) einzuschließen; daß Führungsstangen (5) parallel zur gemeinsamen zentralen Achse (32) der Bearbeitungsscheiben (1, 2) angeordnet sind, um die obere Bearbeitungsscheibe (1) starr zu führen; daß das Kugelmagazin (3) einen stationären Teil (4) aufweist, der den drehbaren Teil des Kugelmagazins (3) lagert; und daß ein Spindelmechanismus (11-14) mit dem stationären Teil (4) des Kugelmagazins (3) verbunden ist, um das Kugelmagazin (3) in Richtung der zentralen Achse (32) der Bearbeitungsscheiben (1, 2) zu verschieben.

2. Läppmaschine nach Anspruch 1, dadurch gekennzeichnet, daß die Drehachse (33) des Kugelmagazins (3) relativ zur Vertikalen geneigt ist, wobei sich die gemeinsame zentrale Achse (32) der Bearbeitungsscheiben (1, 2) vertikal erstreckt.

3. Läppmaschine nach Anspruch 1 oder 2, dadurch gekennzeichnet, daß der Spindelmechanismus (11-14) zum Verschieben des Kugelmagazins (3) einen Zahnkranz (12) aufweist, der von einem Elektromotor (10) getrieben wird und mit einem Stirnrad (13) kämmt, das eine Gewindebohrung aufweist, welche ein Gewindeende der Spindel (14) aufnimmt, wobei das andere Ende der Spindel (14) mit dem stationären Teil (4) des Kugelmagazins (3) verbunden ist.

4. Läppmaschine nach einem der Ansprüche 1 bis 3, dadurch gekennzeichnet, daß die Antriebsmittel (16-18, 26) zum Drehen des drehbaren Teiles des Kugelmagazins (3) einen kontinuierlich verstellbaren Hydraulikantrieb (18) sowie eine damit gekuppelte Verbindungsstange (17) aufweisen, die ein Stirnrad (16) trägt, welches mit einem Zahnkranz (26) am drehbaren Teil des Kugelmagazins (3) kämmt.

5. Läppmaschine nach Anspruch 4, dadurch gekennzeichnet, daß die Verbindungsstange (17) mit Kardangelenken versehen ist.

6. Läppmaschine nach einem der Ansprüche 1 bis 5, dadurch gekennzeichnet, daß die Stelle der Einführung der Kugeln (39) in die Nuten (27) der Bearbeitungsscheiben (1, 2) tiefer liegt als die Ebene des Bodens (34) des Kugelmagazins (3), wogegen die Stelle der Abgabe der Kugeln (39) höher liegt als die Ebene des Kugelmagazinbodens (34).

7. Läppmaschine nach einem der Ansprüche 1 bis 6, dadurch gekennzeichnet, daß der Antriebsmotor (30) zum Drehen der unteren Bearbeitungsscheibe (2) ein Pol-umschaltbarer Motor (30) ist, mit dem die Spindel (6) über ein entlastetes Untersetzungsgetriebe (24, 25) gekuppelt ist.

Revendications

1. Machine à roder pour surfaçer des billes (39), en particulier pour le surfaçage fin de billes de roulements, ladite machine à roder comportant: deux disques de surfaçage (1, 2), disposés coaxialement, superposés, et présentant un axe central commun (32) ainsi que des rainures coaxiales (27) sur leurs faces qui se font face l'une l'autre, lesdites rainures (27) coopérant par paires pour recevoir les billes (39); un magasin à billes (3) tournant entourant les disques de surfaçage (1, 2), des moyens de guidage des billes étant associés avec eux pour guider les billes (39) dans lesdites rainures (27) et hors de ces rainures; une broche principale (6) couplée à un moteur d'entraînement (30) pour entraîner celui (2) des disques de surfaçage qui est le disque inférieur, le disque supérieur (1) étant fixe au cours de l'opération et présentant un évidement pour coopérer avec lesdits moyens qui conduisent les billes; des moyens, incluant un vérin sous pression (8), pour appliquer une pression sur le disque de surfaçage supérieur (1) par rapport au disque de surfaçage inférieur (2) au cours de l'opération; et des moyens d'entraînement (16-18,26) pour entraîner en rotation ledit magasin à billes (3) par rapport auxdits disques de surfaçage (1,2), machine caractérisée par le fait que l'axe de rotation (33) dudit magasin à billes (3) et l'axe central commun (32) desdits disques de surfaçage (1,2) sont inclinés l'un par rapport à l'autre pour former un angle (α); par le fait que les tiges de guidage (5) sont disposées parallèlement audit axe central commun (32) desdits disques de surfaçage (1, 2) pour guider rigidement le disque de surfaçage supérieur (1); par le fait que le magasin à billes (3) comporte une partie fixe (4) sur laquelle est montée la partie tournante du magasin à billes (3); et par le fait qu'un mécanisme à tiges (11-14) est relié à la partie fixe (4) du magasin à billes (3) pour déplacer ledit magasin à billes (3) dans la direction de l'axe central (32) des disques de surfaçage (1,2).

2. Machine à roder selon la revendication 1, caractérisée par le fait que l'axe de rotation (33) du magasin à billes (3) est incliné par rapport à la verticale, l'axe central commun (32) desdits disques de surfaçage (1,2) s'étendant verticalement.

3. Machine à roder selon la revendication 1 ou 2, caractérisée par le fait que le mécanisme à tiges (11-14) prévu pour déplacer ledit magasin à billes (3) comporte une couronne dentée (12) entraînée par un moteur électrique (10) et engrenant avec un engrenage droit (13) qui présente un alésage taraudé recevant une extrémité filetée de la tige (14), l'autre extrémité de ladite tige (14) étant reliée à la partie fixe (4) du magasin à billes (3).

4. Machine à roder selon l'une quelconque des revendications 1 à 3, caractérisée par le fait que lesdits moyens d'entraînement (16,18,26) prévus pour entraîner en rotation la partie tournante dudit magasin à billes (3) comportent un mécanisme d'entraînement hydraulique (18) ajustable en continu ainsi qu'une bielle (17) couplée avec lui et portant un engrenage droit (16) qui engrène avec une couronne dentée (26) montée sur la partie tournante du magasin à billes (3).

5. Machine à roder selon la revendication 4, caractérisée par le fait que la bielle (17) comporte des joints de cardan.

6. Machine à roder selon l'une quelconque des revendications 1 à 5, caractérisée par le fait que le point d'introduction des billes (39) dans les rainures (27) des disques de surfaçage (1, 2) est en-dessous du plan de la partie inférieure (34) du magasin à billes (3), tandis que le point de déchargement des billes (39) est au-dessus du plan de la partie inférieure (34) du magasin à billes.

7. Machine à roder selon l'une quelconque des revendications 1 à 6, caractérisée par le fait que le moteur d'entraînement (30) prévu pour entraîner en rotation le disque de surfaçage inférieur (2) est un moteur à nombre de pôles variable (30) auquel la broche (6) est couplée par l'intermédiaire d'une transmission (24, 25) de réduction de vitesse et de découplage.

Drawing