GRINDING TOOL AND METHOD OF USING IT

Abstract: A grinding tool with two circular rounds (10, 11) disposed on a spindle (16), and pins (12, 13) distributed round the spindle which are parallel to the spindle and bridge the gap between the rounds. The pins are secured in one round (10) while the other round (11) is passed onto the pins and engage shoulders thereon. The rounds are held clamped between a shoulder portion on the spindle and a nut (20) which is screwed onto a threaded portion (19) of the spindle. Between the rounds there are rods (14) pivotally mounted on the pins, which project from the periphery of the rounds.

Description: GRINDING TOOL AND METHOD OF USING IT This invention relates to a grinding tool having two circular rounds disposed on a spindle, and pins distributed round the spindle, which are parallel to the spindle and bridge the gap between the rounds, and rods pivotally mounted on each pin between the rounds, which project from the periphery of the rounds. Grinding tools of this type are used to grind and clean objects and things from coatings of various kinds, for example rust or old paint, the spindle being in¬ serted in a chuck on a drilling machine or other drive machine and the tool, while it is kept in rotation at high speed, up to 2500 revolutions/minute, is engaged with the surface to be treated so that the projecting rods whip against this surface and tear away the coat¬ ing with their ends. Since the rods are exposed to powerful stress, they are made of spring wire which is bent through a few turns to form an eye with which the , rod is passed onto . the pin. In existing embodiments of these grinding tools, the pins are tubular and are secured by press fit in the rounds or - in more expensive constructions - they are secured in the rounds by ball riveting. The spindle is also press-fitted and/or riveted to the rounds. Thus it is a question of a permanently assembled unit which is scrapped after the rods have worn down. The object of the invention is to provide an improved grinding tool of the type referred to here, which allows the rods to be exchanged not only to be replaced by new, similar rods, when they are worn down, but also so as to allow exchange between rods of different types and dimensions, so that the rods can be adapted to the work for which the grinding tool happens to be used. For this purpose, the grinding tool has been given the characteristics appearing from claim 1. The invention also relates to an advantageous method of using such a grinding tool. In order to illustrate the invention an embodi¬ ment thereof will be described in more detail below with reference to the accompanying drawings in which FIG. 1 is an axial sectional view of the grinding tool , FIG. 2 is an end view of the tool, seen from the left in FIG. 1, that is to say from the front end of. the tool , FIG. 3 is a perspective view of the tool, seen from the front end, FIG. 4 is a perspective view from the back end, FIG. 5 is a perspective view of a rod which is stamped from plate or sheet material, FIG. 6 is a perspective view of a bobbin with rods mounted thereon, FIG. 7 is a perspective view of the tool, partially dismantled, illustrating the transfer of the rods from the bobbin of FIG. 6 to one of the pins in the tool, FIG. 8 is an end view of a slit sleeve with rods mounted therein, FIG. 9 is an axial sectional view of the sleeve of FIG. 8, and FIG. 10 is a fragmentary perspective view, partially in section, of the grinding tool with a slit sleeve, provided with rods in a modified embodiment. The grinding tool shown in the drawings comprises two circular steel rounds 10 and 11. Six bolts 12 with smooth shanks and convex heads are passed through holes in the round 10 which is fixed between the head of the bolt 12 and a steel sleeve 13 mounted with a press fit on the shank of the bolt. The shank is longer than the sleeve so that it projects beyond the sleeve at the other end of the bolt, where the annular end surface of the sleeve forms a shoulder on the bolt. The bolts 12 thus secured to the rounds 10 with associated steel sleeves 13 are uniformly distributed round the centre of the round and form pins projecting from one side of the round 10. A number of steel springs 14 with circular cross section are wound helically through some turns to form an eye 15 with which these steel springs are passed onto the steel sleeve 13. The eyes have such a fit on the sleeve that the rods can pivot freely; the play between eye and sleeve can be quite big. The other round 11 is passed loosely onto the bolts 12 with holes which are distributed in the same manner as the bolts round the centre of the round, and the round 11 is adjusted against the end surfaces of the sleeves 13. A spindle 16 is threaded with a square portion 17 through a central square opening in the round 11 and bears with a convex head 18 against one side of this round. With a threaded portion 19, the spindle is freely threaded through a central hole in the round 10 which is also a square opening, so that the rounds are identical . The rounds 10 and 11 are tightened against one another wi h the sleeves 13 as spacing members between the rounds, by means of a nut 20 which is screwed onto the threaded portion, the nut 20 being locked by means of a lock nut 21 with a washer 22 placed between the nuts. The spindle 16 is connected to the unit thus assembled on the spindle, for rotation therewith by means of the square portion 17 introduced into the square opening in the round 11. The spindle has a projecting end portion 23 with which the grinding tool described can be secured in a chuck on a drilling machine or other drive machine. The end portion 23 projects from the threaded portion 19 in the embodiment shown but can instead project from the head 18 which then has the form of an annular flange. How the grinding tool described is used when treating a surface need not be discussed more here*. Nevertheless, a particular finesse in use of the grinding tool described will be mentioned specially. As mentioned above, the round 10 has a square opening for the spindle 16 like the round 11 and this means that the spindle 16 can be mounted either as shown in FIG. 1, that is to say the spindle is inserted from the left in this figure, or in the reverse position, that is to say inserted from the right with respect to FIG. 1. This possibility of mounting the spindle selectively from one side or the other involves an important advantage. When the grinding tool is used, the rods 14, which from the beginning are cut off square at .the free ends thereof, become worn obliquely at the ends at one side after a time, which means that the effectiveness of the grinding tool is reduced. The manufacturers of known grinding tools of the type referred to herein with rods which are permanently mounted in the tool, recommend that the ends of the rods should be filed with a file or other tool so that the rods again have a square end face. It is easy to see that this expedient involves time-consuming work. When the grinding tool according to the invention has been worn down at the ends of the rods 14 by grind¬ ing being effected with the tool rotating counter- -clockwise with respect to FIG. 3, it is not necessary to file the rods, but the nuts 20, 21 are loosened and the spindle is withdrawn from the rounds 10 and 11, after which the spindle is inserted again from the other side and tightened with the nuts. With an unaltered direction of rotation of the drive machine, . the grinding tool is now mounted in the reverse position on the spindle in comparison with before, with the result that the rods strike the object which is being worked, not with the side of the ends which has been worn oblique but with the opposite side which gives a satisfactory working effect. Then when the rods are worn obliquely at said opposite side, the spindle is reversed again for continued satis¬ factory grinding effect. The simple expedient of turn¬ ing the spindle thus replaces, in the grinding tool according to the invention, the time-consuming filing of the ends of the rods which was earlier recommended. What is novel and important is that the rods formed by springs 14 can be exchanged and replaced by other rods. As can easily be seen, the rounds 10 and 11 can be separated after the nuts 20, 21 have been unscrewed from the spindle 16, and the rods 14 can then be removed and other rods mounted, after which the grinding tool is easily assembled again. In this manner, there is the possibility of exchanging the rods 14 when they are completely worn down and replac¬ ing them with new, similar rods, but what is perhaps even more important is that it is possible to mount rods of the type which is best suited to the work for which the grinding tool happens to be used. It is thus possible to have rods of different steel qualities and different diameters, varying for example from 0.30 to 1.50 mm, and the steel springs can also be replaced by rods of glass-filled nylon for example or another material. Thus, there is the possibility of adapting the grinding tool in many ways according to different conditions . In this connection, it may be mentioned that'rods of spring wire which have a diameter which- is less than 1 mm, can only be applied to the pins 12, 13 with difficulty. If the wire is wound helically through a few turns to form an eye in the manner shown in the drawings, there is a risk that the thin wire will straighten out in the helical portion under the influence of centrifugal force, so that the rod breaks away from the tool when this is used. In order to prevent this, it is necessary to lock the helically wound portion in some way, for example by lashing the wire, which involves a complication and makes the tool more expensive. According to the invention, therefore, it is proposed to make such weak rods in the form of stampings 14' as shown in FIG. 5, which are stamped from metal plate or plastics sheet and are shaped with an eye 15'. When such rods are mounted on the pins 12, 13 they can be separated by means of washers o r sleeve- -shaped spacing members of metal o r plastics. In order to make the advantage of being able to exchange the rods 14 o r 14' really attractive, means and a method of easily carrying out this exchange have been provided according to the invention, while at the same time the possibility is afforded of storing associated rods in sets, which provides a good clearness and facilitates the exchange between rods of different dimens ons. According to FIG. 6, the set of rods 14 which is to be mounted on a pin 12, 13, is stored on a tubular bobbin 24 which may appropriately consist of cheap plastics material. The bobbin has a fixed flange 25 at one end while a flange 26 at the other end is made in the form of a head on a stopper 27 which is introduced into the tubular bobbin 24 and is held therein by means of a suitably formed spring lock or by the fact that the stopper 27 is held in the bobbin 24 by friction. In IJURE OMPI 8 are pushed over from the sleeve 13 to the bobbin. Thus it is clear that by storing the rods 14 on bobbins 24 of the kind described, a handy system has been provided for the exchange of rods when these are so worn down that they can no longer be used, or for the exchange of rods of a certain dimension for rods of another dimension and possibly of another material. In the same manner as previously used in many different connections when it is a question of separating elements of different size from one another, bobbins 24 of different colours can be used for rods 14 of different dimensions and/or material, so that the various sets of rods can be stored so as to be easily distinguished from one another. An alternative to the method described for mount¬ ing and removing the rods consists in that the bobbin 24 is dimensioned so that the bobbin with the rods passed thereonto, can be pushed down over the sleeve 13 in which case the bobbin remains in this position between the rounds when the tool is used. The rods are thus always passed onto the bobbin, both during use and storage. The method shown and described seems to be preferable, however, in view of the fact that the bobbin, if it is made of plastics material, as it should be for reasons of cost, is exposed to severe wear when used on the grinding tool. Nevertheless, according to a further development of the invention, a sleeve which is provided, with rods and is adapted to remain on the pins 12, 13 between the rounds 10 and 11 when the grinding tool according to the invention is used, can be made so as to avoid said disadvantage of wear of the sleeves on which the rods are mounted. How this is done according to the invention is illustrated in FIGS. 8 to 10. According to FIGS. 8 and 9, the rods consist of the embodiment shown, an annular bead 28 is provided on the stopper 27 quite close to the flange or head 26 to snap into an annular groove, not shown, in the bobbin 24 and so to hold the stopper 27 detachably in the bobbin. FIG. 7 shows the procedure for mounting the rods 14, which are stored on the bobbin 24, on one of the pins 12, 13 after the round 10 has been removed. After the stopper 27 has been withdrawn from the bobbin, as indicated in FIG. 6, the rods 14 being maintained on the bobbin with the fingers while the bobbin is held in the hand, the end of the tubular bobbin 24, which has been opened by the removal of the stopper 27, is passed onto the end portion of the bolt 12 projecting from the sleeve 13, to engage the shoulder formed by the end face of the sleeve 13, after which the rods 14 are allowed to slide down over the sleeve 13. To facilitate the application of the bobbin 24 to the bolt 12, this may have a bevelled end portion 12' or alternatively the bobbin 24 may have an internal bevel in the end where the stopper 27 is fitted. It is appropriate for the bobbin 24 to have such an internal diameter that it can be passed onto the bolt 12 with an easy sliding fit, and as can easily be seen its external diameter should be sub¬ stantially the same as the external diameter of the sleeve 13 so that when the bobbin 24 is applied as shown in FIG. 7, it allows the eyes 15 of the rods 14 to slide easily from the bobbin 24 down onto the sleeve 13. After each pin 12, 13 has been provided with rods in this manner, the grinding tool is assembled for use in the manner previously described. The removal of the rods is equally easy to carry out, because in that case the empty bobbin 24 is applied to the bolt 12 in the manner described and the reds 14 iUKi- O.V.PI steel nails 29 with a head 30 and these steel nails are passed through radial holes 31 in a resilient, hardened steel sleeve 32 which has an axial slit 33 which extends over the whole length of the sleeve diametrically opposite the holes 31 arranged in an axial row. Through the slit 33, the steel nails 29 can be inserted into the holes 31 and the head 30 too can be introduced into the sleeve through this slit, possibly after slight resilient prizing open of the sleeve, to be engaged with the inside of the sleeve wall in front of the holes 31. Along the row of holes 31, the sleeve 32 has a bulge 34 which forms an axial bead on the outside of the sleeve and corre¬ sponds to an axial groove 35 at the inside of the sleeve, sufficiently large to receive the heads 30 so that the sleeve has an unencumbered circular through aperture despite the presence of the steel nails 29. As a result, the sleeve 32 with the nails 29 mounted therein can be passed onto one of the pins 12, 13 without being hindered by the heads of the nails, so as to have such a fit on the associated pin that the sleeve and hence the rods formed by the nails can turn easily on the pin. In FIG. 10, the sleeve 32 is shown mounted in this manner on one of the pins 12, 13 in the grinding tool previously described, and this figure also shows rods of a somewhat modified construction. The rods are here arranged in pairs in that the rods in each pair are formed from the limbs 29' of a yoke of spring wire bent into U-shape, the web 30' of the yoke being re¬ ceived in the internal groove in the sleeve 32 in the same manner as the heads 30. As a result of the construction as shown in FIGS. 8 to 10, the exchange of rods is even simpler than in the embodiments previously described, but this is achieved at the expense of a somewhat more costly construct! ' on.

Claims: CLAIMS 1. A grinding tool having two circular rounds (10, 11) disposed on a spindle (16), and pins (12, 13) distributed round the spindle, which are parallel to the spindle and bridge the gap between the rounds, and rods (14, 14') pivotally mounted on each pin between the rounds, which project out from the peri¬ phery of the rounds, c h a r a c t e r i z e d in that the pins (12, 13) at one end thereof are fixed in one round (10) and with the other end thereof are introduced into holes in the other round (11) with this round bearing against a shoulder on the pin, and that the spindle (16) bears at a shoulder portion (18) against the one round (11), while a threaded portion (19) of the spindle extends through the other round (10), the rounds (10, 11) being assembled by a nut (20) screwed onto the threaded portion to tighten the rounds towards one another with the pins (12, 13) as spacing members therebetween. 2. A grinding tool as claimed in claim 1, c h a r a c t e r z e d in that each pin consists of a smooth bolt (12) with a head and a steel sleeve (13) mounted with a press fit on the shank of the bolt, the round (10) in which the pin is fixed being gripped between the head and the sleeve and the sleeve ending at a distance from the free end of the shank to form said shoulder. 3. A grinding tool as claimed in claim 8 or 9, c h a r a c t e r i z e d in that the free end of the shank (12) is formed wi h an external bevel. 4. A grinding tool as claimed in any of the claims 1 to 3, c h a r a c t e i z e d in that the spindle (16) is received at a non-round portion (17) in the round (11), engaged by the shoulder portion (18) on the spindle. 5. A grinding tool as claimed in claim 4, c h a r a c t e r i z e d in that said round (11), in order to receive the non-round portion (17) of the spindle (16) has a non-round opening fitting this portion. 6. A grinding tool as claimed in claim 5, c h a a c t e r z e d in that the other round (10) too has a corresponding non-round opening for the passage of the spindle (16), enabling the spindle to be introduced into the rounds selectively from one side or the other of the grinding tool. 7. A grinding tool as claimed in any of claims 1 to 6, c h a a c t e i z e d in that the rods (14) consist of spring wire which is wound helically at one end to form an eye (15) for mounting the rod on the pin (12, 13). 8. A grinding tool as claimed in any of the claims l to 6, c h a r a c t e i z e d in that each rod (14' ) consists of a stamping which is stamped from plate or sheet material of metal or plastics, and : has in one end an eye-shaped portion (15') for mount¬ ing the rod on the pin. 9. A grinding tool as claimed in any of the claims 1 to 8, c h a r a c t e i z e d in that the rods (14, 14') are disposed on a sleeve (24, 32) which is passed onto the pin (12, 13). 10. A grinding tool as claimed in claim 9, c h a r a c t e r i z e d in that the rods (14, 14') are pivotally mounted on the sleeve (24). 11. A grinding tool as claimed in claim 9, c h a r a c t e i z e d in that the rods (29, 29') are secured in the sleeve (32). 12. A grinding tool as claimed in claim 11, c h a r a c t e r i z e d in that the sleeve (32) consists of a slit, preferably resilient sleeve and O. that the rods (29, 29') are passed through the slit in the sleeve and are passed, from the inside, through holes (31) in the wall of the sleeve, a head (30, 30') or the like being provided on the rods to prevent them from being pulled out of the sleeve. 13. A grinding tool as claimed in claim 12, c h a r a c t e r i z e d in that the sleeve (32) is formed with an internal groove (35) to receive the head (30, 30') or the like. 14. A grinding tool as claimed in claim 13, c h a r a c t e r i z e d in that the rods (29) con¬ sist of. steel nails with heads (30). 15. A grinding tool as claimed in claim 13, c h a r a c t e i z e d in that the rods consist of the limbs (29') of a U-shaped yoke of spring wire, the web (30') of the yoke forming a head for the two rods formed by a yoke. 16. A method of using a grinding tool as claimed in any of the claims 1 to 9, c h a r a c t e r i z e d in that the rods (14, 14') for the pins (12, 13) of the grinding tool are stored in sets for each pin on a tubular bobbin (24) with retaining end flanges (25, 26), of which the one (26) at one end is removable, that the round (11) which is passed onto the pins (12, 13) is removed, that the rods are transferred to each pin, in that the bobbin, after removal of the removable end flange, is passed at said one end onto the free end of the pin, after which the rods are pushed over from the bobbin to the pin, and that said round is then replaced. -WREALT OMPI .Λ> WIPO , >,

Inventors: HOLMBERG G
Applicants: HOLMBERG GOTE ESKIL YNGVE, HOLMBERG G
Application year: 1979
Main classification: B24D13
IPC codes: B08B7, B24D13, B24D17