AN ARRANGEMENT FOR GRINDING PLANAR ANNULAR SURFACES

Abstract: Arrangement for grinding planar annular surfaces (6; 8), especially the sealing surfaces of a valve. The arrangement comprises a hub (15) disposed rotationally fixed and bearing a planetary disc (16) mounted rotatably on the hub (15) and bearing in turn around its periphery a plurality of grinding heads (17) each having a grinding disc (19) mounted rotatably in its respective grinding head (17). The planetary disc (16) is effectively connected to a drive shaft (4) by means of which it can be caused to rotate relative to the hub (15). Between the hub (15) and the grinding discs (19) there are effective connections (31, 32, 33, 34, 35, 36) adapted to cause the grinding discs (19) to rotate relative to their respective grinding heads (17) when the planetary disc (16) is rotated relative to the hub (15). It is characteristic of the invention that the drive shaft (4) is mounted in the centre of the hub (15) in such a way that it can be pivoted through approximately 180<o> in a plane normal to the planetary disc (16). This enables the grinding discs (19) to coincide with the planar annular surfaces automatically and irrespective of the inclination of the drive shaft (4) relative to the said planar annular surfaces.

Description: An Arrangement, for Grinding Planar Annular Surfaces The present invention relates to an arrangement for grinding planar annular surfaces, especially the sealing surfaces of a valve, comprising a hub disposed rotation- ally fixed and bearing a planetary disc mounted rotat- ably on the hub and bearing in turn around its periphery a plurality of grinding heads each having a grinding disc mounted rotatably on its respective grinding head, this planetary disc being effectively connected to a drive shaft by means of which the planetary disc can be caused to rotate relative to the hub, and wherein there are effective connections between the hub and the grinding discs, adapted to cause the grinding discs to rotate re¬ lative to their respective grinding heads when the planet¬ ary disc is rotated relative to the hub. Grinding arrangements of this type are used in parti¬ cular for the final grinding of the sealing surfaces of valves. In the two main types of valve which exist, namely, shut-off valves and slide valves, the said sur¬ faces are broadly speaking at right angles to the longi- tudinal extent of the valve spindle, or form a small ang¬ le with it. This has meant that for the final grinding of these two kinds of valve two different kinds of grind¬ ing arrangement have been required, which is naturally ex¬ pensive and impractical, particularly as the final grind- hg is usually carried out on site by special assembly personnel. A primary object of the present invention is to pro¬ vide a grinding arrangement of the kind named in the intro¬ duction which is for general use, at least for the most usual kinds of valve, and this is made possible due to the fact that the drive shaft is mounted in the centre of the hub in such a way that it can be pivoted through approxi¬ mately 180° in a plane normal to the planetary disc, thus enabling the grinding discs to coincide with the planar annular surfaces automatically and irrespective of the inclination of the drive shaft relative to the said planar annular surfaces. The invention will be described in more detail in the following with reference to the accompanying drawing on which Figures 1a and 1b show a grinding arrangement according to the invention being used for the final grind¬ ing of sealing surfaces on a slide valve and on a shut- off valve, respectively. Figure 2 is a side view show- ing an embodiment of a grinding arrangement accordingto the invention during the grinding of the sliding compon¬ ent of a valve. Figure 3 is a detail showing the con¬ struction of the grinding arrangement shown in Figure 2, in perspective and at an angle from above. Figure is a cross-section through the grinding arrangement. In Figures 1 and 2 on the drawing, 1 is the desig¬ nation of a grinding arrangement according to the inven¬ tion which is mounted on a framework 2 via a tubular ele¬ ment 3 in which the drive shaft of the grinding arrange- ent is rotatably mounted. This shaft may be driven by means of a hand-drill tool 5 5 operated by electricity or compressed air, which can be effectively connected to the outer end of the drive shaft -Ψ. Via the framework 2 the grinding arrangement can be mounted on a valve housing 6 for the final grinding of the valve seat 6, Figures a and 1b, or on a cone cradle 7 ^ov the final grinding of the cone or sliding component 8 of the valve, Figure 2. The purpose of the cone cradle 7 is to serve as a support for the sliding component 8 of the valve and for the framework 2. The latter comprises a mechanism 9 for cen¬ tring and adjusting the depth of the grinding arrange¬ ment, together with stop devices 10 and 11 respectively for the centring and depth-adjustment. The setting of the appropriate grinding pressure is effected by means of a wheel 12 and a spindle 3 with a thread on it, and a pushing and pulling spring 14-. The grinding arrangement comprises a hub 15 which bears a planetary disc 16 mounted so that it can rotate on the hub. Around its periphery the disc has a plural¬ ity of grinding heads ; in the embodiment shown on the drawing the number of grinding heads is five. Each grind¬ ing head 7 comprises a part 18 which is mounted so that it may slide radially in the planetary disc 16, and a grinding disc 19 mounted rotatably on this part. The planetary disc 16 is effectively connected to the drive shaft 4- by means of which the planetary disc 16 can be caused to rotate relative to the hub 15. According to the invention the mounting of the drive shaft 4- is positioned centrally on the hub 1 in such a way that the drive shaft can be pivoted through approxi- mately 180° in a plane normal to the planetary disc 16. Furthermore, between the hub 15 and the grinding discs19 there are effective connections adapted to cause the grinding discs 19 to rotate relative to their respective grinding head part 18 when the planetary disc 16 is ro- tated relative to the hub 15. The manner in which the planetary disc 16 is effect¬ ively connected to the drive shaft 4-, how the drive shaft 4- is mounted in the hub 15 and how the latter is effect¬ ively connected to the grinding discs 19 will now be des- cribed with reference in particular to Figures 3 and 4-. As can be seen in the said Figures, the hub 15 is equipped with two brackets 20, 21 in which a transverse part 22 on the tubular element 3 is mounted rotatably so that the said element 3 and with it the drive shaft 4- can be pivoted through approximately 180° in a plane nor¬ mal to the planetary disc 16. The effective connection between the drive shaft 4- and the planetary disc 16, which is effective in every angular position within the said angle of 180°, consists of two shafts 23, 24- which are mounted rotatably in the transverse part 22, approxi¬ mately parallel to the planetary disc 16. The ends of the shafts 23, 24- are equipped with conical gear wheels 25, 26, 27, 28, of which the opposing gear wheels 25, 26 engage with a conical gear wheel 29 on the drive shaft4-. The remaining gear wheels 27, 28 on.the shafts 23, 24- respectively engage with a conical gear ring 50 disposed concentrically on the planetary disc 16. The rotation of the planetary disc 16 relative to the hub 15 when the shat 4- is rotated is achieved by means of this effective connection. In order to achieve the rotation of the grinding discs when the planetary disc 16 is rotated relative to the hub 15 an effective connection is required between the latter and the respective grinding discs 1 . For each of the respective grinding discs 19 this consists of a spindle 51 mounted rotatably in the planetary disc and lying in a plane which is approximately parallel withthat in which the intermediate shafts 23, 24- lie. The spindle 31 is equipped with two conical gear wheels 32, 33, one32 of which engages with a conical gear ring 34- disposedcon- centrically on the hub 15- The other gear wheel 33 en¬ gages with a conical gear wheel 35 disposed at one end of a shaft 36 which is mounted rotatably in the part 18, and to the other end of which the grinding disc 19 is attached. The gear wheel 33 can be displaced along the spindle 31 in order to allow valves of different sizes to be ground. By means of the above-described effective connections, when the drive shaft 4- is rotated the grinding discs 9 rotate around their shafts 36 and, due to the rotation of the planetary disc 16 relative to the hub 15, they also move in a circular path round the axis of rotation ofthe planetary disc 16. Very smooth sealing surfaces are ob¬ tained in this way. Moreover, the effective connection between the drive shaft 4- and the planetary disc 16 is constructed in such a way that it allows the grinding discs 19 to be angled relative to the drive shaft 4-with¬ in an angular range of approximately 180°.

Claims: P a t e n t C l a i m s 1. An arrangement for grinding planar annular sur - faces (6; 8), especially the sealing surfaces of valves, comprising a hub (15) disposed rotationally fixed and bearing a planetary disc (16) mounted rotatably on the hub (15) and bearing in turn around its periphery a plur¬ ality of grinding heads (17) each having a grinding disc (19) mounted rotatably on its respective grinding head (17), this planetary disc (16) being effectively con¬ nected to a drive shaft (4-) by means of which the planet- ary disc (16) can be caused to rotate relative to the hub (15), and wherein there are effective connections (31, 32, 33, 34-, 35, 36) between the hub (15) and the grinding discs (19), adapted to cause the grinding discs (19) to rotate relative to their respective grinding heads (17) when the planetary disc (16) is rotated relative to the hub (15), characterised.-in Jthat the drive shaft (4-) is mounted in the centre of the hub (15) in such a way that it can be pivoted through approximately 180° in a plane normal to the planetary disc (16), thus enabling the grinding discs (19) to coincide with the planar annular surfaces automatically and irrespective of the inclination of the drive shaft (4-) relative to the said planar annu¬ lar surfaces. 2. An arrangement according to Patent Claim 1 wherein a conical gear wheel (29) disposed on the drive shaft (4-) engages with at least one conical gear wheel (25, 26) attached to an intermediate shaft (23, 24-) mounted rotat¬ ably on the hub (15), this intermediate shaft (23, 24-) in turn being effectively connected to the planetary disc (16), characterised in that the intermediate shaft (23,24-) which preferably consists of two shaft parts (23, 24-) disposed centrally on the planetary disc (16) with a com¬ mon centre line, is approximately parallel with the planetary disc (16) and is equipped with conical gear wheels (27, 28) which engage with a conical gear ring (30) disposed concentrically on the planetary disc (16). 3. An arrangement according to Patent Claims 1-2, characterised in that the effective connection between the hub (15) and the respective grinding discs (19) con¬ sists of a spindle (31) lying in a plane which is ap¬ proximately parallel with that in which the said inter¬ mediate shaft (23, 24-) lies, to which spindle (31) a rotary movement is transmitted via a conical gearwheel (32) attached to the spindle (31) and engaging with a conical gear ring (34-) disposed concentrically on the hub (15), and that the rotary movement of the spindle is transmitted to the respective grinding discs (19) by means of bevel gearing (33, 35) which can be displaced axially along the spindle (31) but cannot rotate relative thereto, thereby accomplishing the mounting of the grind¬ ing heads (17) in the planetary disc (16) so that they can be displaced radially.

Inventors: LARSSON LARS-INGE, LARSSON, LARS-INGE
Applicants: LARSSON LARS ING MED FA, LARS-INGE LARSSON MED FIRMA LARSSONS INDUSTRIMEKAN
Application year: 1985
Main classification: B24B15
IPC codes: B24B15