GB2071567A - Spindle assembly - Google Patents

Abstract

To eliminate the usual protruding unit securing a saw blade or cut-off disc 29 to a spindle in a cut-off machine, the spindle assembly, comprising tubular housing 10 has journalled therein an axial sleeve 13 formed with a spigot 19 at one end for an inner clamping disc 20 and fitted with a drive pulley 14 at the other end. An axial draw bar 30 engages threadedly with a boss 26 provided on an outer clamping disc 27 and projecting through the saw blade or disc 29 and into the sleeve 13. Nut 33 on the other end of the draw bar 30 permits the outer disc 27 to be drawn towards the inner disc 20 for clamping the blade or disc 29. <IMAGE>

Description

SPECIFICATION Spindle assembly This invention concerns a spindle assembly for use in mounting a saw blade or abrasive cut-off disc in a cut-off machine.

Such spindle assemblies are incorporated, for example, in cut-off mahcines of the kind comprising a balanced head (of which the spindle assembly forms a part) adapted to be displaced so as to perform a cutting operation on a workpiece, such as a metal casting, and usually comprise a tubular housing within which a spindle is journalled. Drive means, such as a drive pulley, is provided on the spindle at one end where it protrudes from the housing, and usually at the other end a protruding threaded portion of the spindle projects through a central hole in the saw blade or cut-off disc which is secured by a clamping nut on the threaded portion.

Since substantial torque has to be transmitted to the saw blade or disc, the spindle and its nut must be relatively robust. Accordingly, the clamping nut protrudes a relatively substantial distance axially of the blade or disc at the side remote from the housing and can be restrictive of the location at which a workpiece can be cut. In the case of metal castings, there are, of course, optimum cutoff locations for severing the useful casting parts from associated sprue necessarily formed integrally with the useful part during the casting operation, to ensure that any residual machining-away of non-required parts is at a minimum. The clamping nut can, in certain instances, prevent the severing operation being effected at the optimum location, so that the amount of machining which has to be effected after cutting off is significantly increased.

An object of the present invention is to provide a spindle assembly of the kind above discussed wherein the clamping nut is eliminated from the saw blade or cut-off disc end of the spindle, so that more advantageous cut-off locations can be selected than have hitherto been possible.

With this object in view, the present invention provides a spindle assembly for use in mounting a saw blade or cut-off disc in a cut-off machine comprising a tubular housing having an axial sleeve journalled for rotation therein, said sleeve providing for the mounting, at one end thereof, of an inner annular clamping disc thereon and, at the other end, of drive means for rotating the sleeve, and axial draw bar extending through the sleeve and serving to permit an outer clamping disc to be drawn towards the inner annular clamping disc for clamping a saw blade or a cut-off disc between said clamping discs.

To facilitate connection between the outer clamping disc and the draw bar, the sleeve preferably has, at the said one end, a bore portion of enlarged diameter into which fits a central boss projecting axially from the outer clamping disc, and the draw bar engaging threadedly into said boss.

The other end of the draw bar may have thereon a nut abutting the corresponding end of the sleeve; the thread at the one end of the draw bar is then preferably of opposite hand to the thread at the other end of the draw bar. This arrangement permits the outer clamping disc to be released, either by removing the nut and drawing the draw bar out through the sleeve at the saw blade or cut-off disc end of the sleeve or by unscrewing the draw bar out of the boss.

The form of the sleeve is preferably such as to provide, at the said one end thereof, a spigot on which the inner annular clamping disc is disposed, a key between the spigot and the inner clamping disc ensuring that the latter rotates with the sleeve.

The invention will be described further, by way of example, with reference to the accompanying drawings, it being understood that the following description is illustrative, and not restrictive, of the scope of the invention.

In the drawings: Fig. 1 is sectional elevation of a preferred embodiment of the spindle assembly of the invention; and Fig. 2 is a sectional elevation of part of a modified draw bar for use in place of the draw bar of the assembly shown in Fig. 1.

Illustrated in Fig. 1 is the preferred embodiment of the spindle assembly of the invention, for use in mounting a circular saw blade or cut-off disc 29 in a cut-off machine, comprises a generally tubular metal housing 10 to the outer curved surface 1 1 of which is fixed a bracket (not shown) which enables the assembly to be bolted to a complementary bracket (not shown) at an end of a cut-off machine arm (not shown), to form a head of the machine. The arm is balanced to enable the head readily to be displaced for the saw blade or disc 29 to be brought to a desired cutting position.

Journalled and located axially within the housing 10 by means of two axial thrust ball bearings 12 and axial bearing 37 is a rotatable sleeve 13 one end the "drive" end of which projects from the housing 10 and has secured thereon a drive pulley 14 driven from a motor (not shown) mounted on the arm. Secured to respective ends of the housing 10, by means of, for example, screws, only one 1 5 of which is shown, are respective collars 16, 17. Said collars 16, 1 7 serve for the retention of the bearings 1 2 and bearing 37 within the housing 10.

Adjacent its other end (the "cutter" end), the sleeve 13 is formed with an integral enlarged collar 18 beyond which extends an end portion of the sleeve 13, which end portion constitutes a spigot 19 projecting from the sleeve 13. An annular inner clamping disc 20 locates on the spigot 19 and is keyed thereto by means of key 21, that face of the inner clamping disc 20 which faces the sleeve 13 abutting against the collar 18 to position the clamping disc 20 thereby. The aforementioned face is provided with an annular groove 22, into which projects an annular rib 23 to minimise ingress of foreign matter between the inner clamping disc 20 and the end portion of the sleeve 1 3. That face of the clamping disc 20 remote from the sleeve 13 is centrally recessed so that an outer circumferential region of the said face constitutes an annular clamping surface 24.

The sleeve 13 has an enlarged bore portion 25 at the cutter end into this fits a central internallythreaded boss 26 formed integrally with an outer clamping disc 27 which, like the inner clamping disc 20, is centrally recessed so that it has, at an outer circumferential region and on the same side as the projecting boss 26, a respective circumferential annular clamping surface 28. The outer clamping disc 27 and the inner clamping disc 20 serve to retain between them the circular saw blade or abrasive cut-off disc 29. A rod-like draw bar 30, threaded on both of its ends 31 and 32, which are of reduced diameter compared with the rest of the draw bar 30, extends through the sleeve 13 and engages by one of its ends 31, with a right hand thread with the boss 26 of the outer clamping disc 27.At its other end 32, this draw bar 30 has thereon a left hand threaded nut 33 which abuts against the confronting end of the sleeve 13. Formed integrally with end 32 of the draw bar 30 is a square sectioned extension 34 by which the draw bar 30 can be rotated by a suitable tool (not shown).

Because the draw bar 30 is screwed tightly in the boss 26 of the outer clamping disc 27, tightening of the nut 33 serves to ensure that the saw blade or cut-off disc 29 is firmly and securely clamped in place. Corresponding tightening and clamping can be achieved by holding the outer clamping disc 27 and the nut 33 stationary, and rotating the draw bar 30, the opposite hands of the threads on the outer clamping disc 27 and nut 33 ensuring the clamping. For removing the saw blade or cut-off disc 29, the draw bar 30 can be released either by removing the nut 33 (in which case the draw bar 30 can be drawn right through the sleeve 13) or by unscrewing the draw bar 30 out of the outer clamping disc 27.

The principal advantage of the arrangement of the invention resides in the fact that the outer clamping disc 27 needs to be only of a very shallow axial thickness, so that there is the minimum of protuberance at the corresponding side of the saw blade or cutoff disc 29.

Accordingly, the blade or cut-off disc 29 can, in each cutting operation, be brought as close as possible to the optimum cutting position so that subsequent machining of a cut-off workpiece ze.g.

casting not shown) is minimised.

Illustrated in Fig. 2 is part of a modified draw bar 38, having a threaded extension 35, onto which the saw blade or cut-off disc 29 can be secured by a nut (not shown), which draw bar 38 can be provided for alternative use in the place of the bar 30 illustrated in Fig. 1, e.g. in cutting operations where space considerations are not important and the standard arrangement having a nut securing the blade or cut-off disc is required. That end of the draw bar 38 adjacent the threaded extension 35 has a portion 36 of an enlarged diameter as compared with the rest of the draw bar 38. The dimensions of this portion 36 are the same as or slightly less than the interior dimensions of the enlarged bore portion 25 of the sleeve 13.

In the described and illustrated spindle assembly drive means may be provided for mechanically rotating the draw bar 30, or the nut 33 thereon. Such a possibility can be employed for providing for automatic blade or cut-off disc exchange.

Claims (6)

1. A spindle assembly for use in mounting a saw blade or cut-off disc in a cut-off machine comprising a tubular housing having an axial sleeve journalled for rotation therein, said sleeve providing for the mounting, at one end thereof, of an inner annular clamping disc thereon and, at the other end, of drive means for rotating the sleeve, an axial draw bar extending through the sleeve and serving to permit an outer clamping disc to be drawn towards the inner annular clamping disc for clamping a saw blade or cut-off disc between said clamping disc.

2. A spindle assembly as claimed in claim 1 wherein the sleeve has, at the said one end, a bore portion of enlarged diameter into which fits a central boss projecting axially from the outer clamping disc, the draw bar engaging threadedly into said boss.

3. A spindle assembly as claimed in claim 2 wherein the said other end of the draw bar has thereon a nut abutting the corresponding end of the sleeve.

4. A spindle assembly as claimed in claim 3 wherein the thread at the one end of the draw bar is off opposite hand to the thread at the other end of said draw bar.

5. A spindle assembly as claimed in any preceding claim wherein the said one end of the sleeve is formed with a spigot on which the inner annular clamping disc is disposed, a key between the spigot and the inner clamping disc ensuring that the latter rotates with the sleeve.

6. A spindle assembly substantially as hereinbefore described with reference to and as illustrated in the accompanying drawing.