AU672999B2 - Variable speed belt drive assembly - Google Patents

Description

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AUSTRALIA

r It it t Irrr r t t ;ir: r trrtii I r Patents Act 1990 COMPLETE SPECIFICATION FOR A STANDARD PATENT C. a Sal ala 44..

Name of Applicant: Actual Inventor: Address for Service: Invention Title: VICTOR VERRECCHIA Victor Verrecchia TREVOR DREDGE ASSOCIATES Patent Trade Mark Attorneys 13th Floor, 379 Queen Street BRISBANE, QLD, 4000 GPO Box 1339, BRISBANE, 4001 "Variable Speed Belt Drive Assembly" Details of Associated Provisional Application No: Australian Patent Application October, 1992.

No. PL5102 filed The following statement is a full description of this invention, including the best method of performing it known to me: TECHNICAL FIELD OF THE INVENTION 4 00u *0,4 9590IOW THIS INVENTION relates to a variable speed endless belt drive assembly and in particular, but not limited to a variable speed endless belt drive assembly for a lathe or the like.

BACKGROUND ART Prior drive assemblies for lathes have not enabled easy and convenient speed changes. The existing drives usually involve concentric pulley arrangements. The only way to change the speed was to change the drive belt on to a different pair of pulleys. With this arrangement, changing speed is a time consuming procedure. In addition, speeds are not continuously variable over the range of speeds available.

OUTLINE OF THE INVENTION It is an object of the present invention to alleviate at least to some degree the aforementioned problems associated with the prior art.

In one aspect therefore, the present invention resides in a variable speed endless belt drive assembly comprising a fixed drive shaft and a fixed driven shaft spatially fixed relative to the drive shaft, a speed control assembly between the two shafts and first and second endless V-belts, a drive pulley on the drive shaft and a driven pulley on the driven shaft, the speed control assembly comprising a pair of transversely spaced and relatively fixed discs and a slide disc between the fixed discs, the fixed discs and slide disc sharing a common shaft, the first endless V-belt passing over the drive pulley and the second endless belt passing over the driven pulley with one V-belt passing between the slide disc and one of the fixed discs and the other V-belt passing between the slide disc and the other Sfixed disc, the slide disc and the fixed discs having confronting cone shaped 9 0 1 I surfaces in alignment with the V-belts, the speed control assemrnbly being physically moveable in a direction extending between the drive and driven pulleys to increase tension on one belt which in turn reduces tension on the other so that the space between the respective fixed discs and the slide disc changes to thereby control the speed of the driven pulley, the speed control assembly being mounted on a carriage which travels on a straight guide, the guide being set at an angle to the central axis of the belts in order to maintain alignment of the Vbelts with the cnne shaped surfaces of the discs as the speed control assembly is moved along the guide. Preferably, adjacent surfaces of the slide disc and the 10 respective fixed discs diverge radially from each other at the same angle.

Preferably, the angle of divergence is matched to the cross-sectional shape of the endless belts being used. Typically, the surfaces diverge with an included angle of 200 between them or each diverges at an angle of 100 to the central axis of the endless belt.

The guideway is typically set at an angle half the included angle between the central axis of the belt and the diverging surfaces of the slide and fixed discs.

In the case of this being 100, the guide travels along a line parallel to a line set _at 5' to the central axis of the endless belt.

Belt size can range to suit the application but wider belts give a wider speed cover as the slide and fixed discs can be of greater diameter. Speeds of 140RPM to 1300RPM can be achieved using a disc diameter of i65mm to 170mm. A 22mm wide belt is suitable for this arrangement.

In another aspect, the invention resides broadly in a lathe including a variable speed endless belt drive assembly as broadly described above.

H ~BRIEF DESCRIPTION OF THE DRAWINGS I- In order that the invention can be more readily understood and be put into practical effect, reference will now be made to the accompanying drawings illustrating preferred embodiments of the invention and wherein:- Figure 1 is a pictorial view illustrating one embodiment of a variable speed belt drive assembly according to the present invention; and Figure 2 is a part section view illustrating a further embodiment of the present invention.

METHOD OF PFRFORMANCE Referring to the drawings and initially to Figure 1, there is illustrated a 0 variable speed endless belt drive assembly 10 for a lathe or the like comprising V a fixed drive shaft from a motor and a fixed driven shaft at a headstock both of o: which are not shown but each shaft has a pulley and respective endless belts 11 hi 4 ,and 12. The belts travel over a speed control assembly shown generally at 13.

The speed control assembly 13 comprises a pair of transversely spaced and 1 5 relatively fixed discs 14 and 15 and a slide disc 16 between the fixed discs 14 and 15. The fixed discs and the slide disc share a common shaft 17 which rotates in a bearing assembly 18. The respective endless belts 11 and 12 pass between Sthe slide disc 16 and the respective fixed discs 14 and 15 as shown.

The bearing assembly 18 is mounted on a carriage 19 which travels on guide rails 20 and 21 relative to a fixed support 22. A chain drive 23 is used for this purpose. It will be appreciated that as the speed control assembly is moved back or forth between the drive and driven pulleys that a proportional decrease and increase in tension on the belts 11 and 12 will occur so that the space between the respective fixed discs 14 and 15 and the slide disc 16 will change so that the position of the belts 11 and 12 will change in accordance with the NT Q spacing and thereby control of the speed of the driven pulley coupled to the belt 12 can be made.

In the Figure 1 embodiment, the belts 11 and 12 are trapezoidal in crosssection having a 10' taper on the edges of the belt and accordingly, the fixed pulleys 14 and 15 and the slide pulley 16 have opposed diverging faces which are set to match this angle. The guide rails 20 and 21 are set at a 50 angle to the central axis of the belts to take into account the cross-sectional shape of the belts.

Referring to Figure 2, there is illustrated in section a variable speed endless belt drive assembly 10 and where appropriate, like numerals have been used to 10 illustrate like features. In the embodiment of Figure 2, the taper on the fixed and oo' sliding discs 14, 15 and 16 is different from that in the Figure 1 embodiment. In a Figure 2, only one side of the discs has been shown. As can be seen, the slide disc 16 is mounted on a bronze bearing 24 which extends along the shaft 17 and is housed on the shaft with sufficient space to cater fc.r sidewards movement of is the slide disc 16 between the fixed discs.

It will be appreciated from the foregoing that the present invention has amany applications other than specifically to a variable speed endless belt drive Sassembly for a lathe and likewise, it will be appreciated that whilst the above has been given by way of illustrative example of the present invention, many variations and modifications thereto will be apparent to those skilled in the art without departing from the broad ambit and scope of the invention as set forth in the appended claims.

Claims (8)

1. A variable speed endless belt drive assembly cormtrising a fixed drive shaft and a fixed driven shaft spatially fixed relative to the drive shaft, a speed control assembly between the two shafts and first and second endless V-belts, a drive pulley on the drive shaft and a driven pulley on the driven shaft, the speed control assembly comprising a pair of transversely spaced and relatively fixed discs and a slide disc between the fixed discs, the fixed discs and slide disc sharing a common shaft, the first endless V-belt passing over the drive pulley and the second endless V-belt passing over the driven pulley with one V-belt passing between the slide disc and one of the fixed discs and the other V-belt passing :.obetween the slide disc and the other fixed disc, the slide disc and the fixed discs having confronting cone shaped surfaces in alignment with the V-belts, the speed o.control assemly being physically moveable in a direction extending between the drive and driven pulleys to increase tension on one belt which in turn reduces tension on the other so that the space between the respective fixed discs and the slide disc changes to thereby control the speed of the driven pulley, the speed control assembly being mounted on a carriage which travels on a straight the guide being set at an angle to the central axis of the belts in order to maintain alignment of the V-belts with the cone shaped surfaces of the discs as the speed control assembly is moved along the guide.

2. A variable endless belt drive assembly according to claim 1 where;i adjacent surfaces of the slide disc and the respective fixed discs diverge radially from each other.

3. A variable speed endless belt drive assembly according to any one of the preceding claims wherein the slide disc and fixed discs diverge at an angle of L divergence and the endless belts being used have a profile matched to the angle of divergence of the discs.

4. A variable speed endless belt drive assembly according to any one of the preceding claims wherein the surfaces of the discs diverge with an included angle of about 200 between them or each diverges at an angle of about 100 to the central axis of the respective endless belt.

A variable speed endless belt drive assembly according to claim 4 wherein the guide rails are at an angle being about half the included angle between the central axis of the belts and the cone-shaped surfaces of the siide and fixed discs.

6. A variable speed endless belt drive assembly according to any one of the preceding claims wherein the guide comprises a pair of spaced guide rails.

7. A variable speed endless belt drive assembly wherein the carriage is driven along the guide by means of a chain drive.

8. A lathe including a variable speed endless belt drive assembly according i to any one of the preceding claims. W9. A variable speed endless belt drive assembly substantially as described with reference to the accompanying drawings. DATED this 19th day of August, 1996. VICTOR VERRECCHIA By his Patent Attorneys SINTELLPRO *1 *1 ABSTRACT A variable speed endless belt drive assembly 10 for a lathe or the like comprising a fixed drive shaft from a motor and a fixed driven shaft at a headstock both of which are not shown but each shaft has a pulley and respective endless belts 11 and 12. The belts travel over a speed control assembly shown generally at 13. The speed contrl1 assembly 13 c-mprises a pair of transversely spaced and relatively fixed discs 14 and 15 and a slide disc 16 between the fixed discs 14 and 15. The fixed discs and the slide disc share a common shaft 17 which rotates in a bearing assembly 18. The respective endless belts 1 1 and 12 pass between the slide disc 16 and the respective fixed discs 14 and 15 as shown. i S S 5145 555, i S