LATHE

Abstract: A lathe (10) having a lathe bed (11) on which is mounted a cutting station at which a cutting tool (13) can be mounted, a guide defining a guide path for guiding relative feeding movement between a workpiece holder (14) and the cutting tool (13), and drive means (15) for relatively moving the workpiece and the cutting tool (13) to engagement with each other. In order to provide a gap-swing facility, and avoid present requirement in known lathes to provide a "removable gap-piece", the invention provides a guide in the form of three parallel guide elements, namely a main front guide-way (17), a tailstock bed-way (18) and a rear ante-roll guide-way (19), which are spaced apart from each other and relative to the centre line (16) of the workpiece holder (14). The three parallel guide elements (17, 18, 19) gap or cavity so that the required gap-swing facility is provided substantially without loss of guide-way support.

Description: LATHE This invention relates to a lathe having a lathe bed. a cutting station provided on the lathe bed and at which a cutting tool can be mounted, a guide mounted on the lathe bed and defining a guide path for guiding relative movement between a workpiece and the cutting tool, and drive means for relatively moving the workpiece and the cutting tool to engagement with each other. In known designs of lathe, it is usual to provide a so-called "removable gap- piece", and which (when removed) temporarily gives an increased "gap-swing" capacity for a short distance in front of the usual faceplate which holds the workpiece. However, with existing designs, the presumed requirement of lathe operators for a removable gap- piece facility presently imposes a number of technical drawbacks, which can include (a) loss of overall accuracy (b) reduction of rigidity and (c) undesirable wear characteristics of the lathe. The present invention therefore seeks, in one aspect, to provide an improved design of lathe which allows for elimination of a traditional removable gap piece, while at the same time seeking to provide improved overall accuracy in operation, rigidity and enhanced wear characteristics of the lathe. According to one aspect of the invention there is provided a lathe having a lathe bed on which is mounted: a) a cutting station at which a cutting tool can be mounted; b) a guide defining a guide path for guiding relative feeding movement between a workpiece holder and the cutting tool; and c) drive means for relatively moving the workpiece and the cutting tool to engagement with each other: in which the guide comprises three parallel guide elements which are spaced apart from each other and relative to the centre line of the workpiece holder such that a permanent gap or cavity is defined in the lathe bed structure to provide a gap-swing facility and substantially without loss of guide-way support. Preferably, the three parallel guide elements comprise a main front guideway, a tailstock bed-way, and a rear anti-roll guideway. The drive means may take the form of a usual lead screw arrangement. The cutting tool is preferably carried by a travelling assembly movable along the guide elements, and including two front carriages slidable along the main front guideway. and a further carriage unit slidable along the rear anti-roll guideway. The preferred provision of a three-point linear guideway configuration (two carriages slidable along the front main guideway and one preferably less heavily preloaded carriage unit sliding on the rear anti-roll guideway) allows for some geometric misalignment, thus further improving overall slide-way accuracy. The geometry of the arrangement of the guide elements, in relation to the centre line of the workpiece holder (main spindle centre line) is arranged, as indicated above, to provide a permanent cavity or gap in the lathe bed, and to allow for appropriate extra "gap-swing" which may be required, without the usual loss of slide-way support which naturally occurs when a traditional gap piece is removed in known designs of lathe provided with this facility. Further advantages of the embodiment of the invention are that the loss of accuracy, often introduced by non-perfect refitting of a traditional gap piece (after removal for "swing-in gap work") is eliminated. In addition, the length limit imposed by a gap piece (to the desirably long and narrow) main guideway may also be eliminated, thus giving opportunity to increase this length and consequently provide improved slideway accuracy, rigidity and enhanced wear properties. According to a further aspect of the invention there is provided a lathe having a lathe bed on which is mounted: a) a cutting station at which a cutting tool can be mounted; b) a guide defining a guide path for guiding feeding movement of the cutting tool relative to a workpiece holder; and c) drive means for advancing the cutting tool into engagement with a workpiece when mounted on said holder; in which the lathe excludes provision of a removable gap piece, and in which said guide comprises three parallel guide elements which are spaced apart from each other and relative to the centre line of the workpiece holder that a permanent gap or cavity is defined in the lathe bed to provide a gap-swing facility and substantially without loss of guide-way support for the movement of the cutting tool. -j- \ preterred embodiment of lathe according to the invention will now be described in detail, by way ot example onl\ . w ith reference to the accompanying drawings, in w hich. Figure 1 is a plan v iew of part of the lathe according to the invention: Figure 2 is a front view of the part of the lathe shown in Figure 1; and Figure 3 is an end view and taken on sectional line X-X in Figure 2. Referring now to the drawing, there is shown a preferred embodiment of lathe according to the invention, and which eliminates provision of traditional removable "gap- piece". A gap-piece is traditionally provided in existing designs of lathe, in order to provide, temporarily, an increased gap-swing capacity for a short distance in front of the usual face plate holding a workpiece, whilst the gap piece is removed. The lathe according to the invention excludes requirements for provision of a removable gap piece, while still providing a gap swing facility, and while at the same time also giving improved and increased overall accuracy, rigidity and wear characteristics to the lathe according to the invention. The lathe is designated generally by reference 10, and includes a lathe bed structure 11 on which is mounted a travelling cutting station assembly 12 which carries cutting tool 13. The bed 11 also mounts a guide which defines a guide path for guiding relative feeding movement between a workpiece (not shown) carried by workpiece holder 14 and the cutting tool 13. There is also provided drive means for relatively moving the workpiece and the cutting tool to engagement with each other, and which takes the form of a lead screw arrangement 15. The travelling cutting station assembly 12 is slidable along three parallel guide elements, which constitute the tool guide, and which are spaced apart from each other, and also relative to the centre line 16 of the workpiece holder 14, which comprises usual main spindle centre line. The three parallel guide elements which make up the tool guide comprise a main front guideway 17, a tailstock bed-way 18 and a rear anti-roll guideway 19. By virtue of the geometry of the arrangement of the three parallel guide elements, both in relation to each other, and also relative to the centre line 16 of the workpiece holder. a permanent gap or cavity can be defined in the lathe bed structure 11 to provide a guide-swing facility, and substantially without loss of slideway (guide wav) support. The cutting tool 13 is carried by travelling assembly 12 which is slidable along the guide elements, and comprises two front carriages 21 and 22 which are slidable along the main front guideway 17, which is a long narrow front guideway. The travelling assembly 12 also includes a less heavily pre-loaded carriage unit 23 which is slidable along the rear anti-roll guideway 19. Therefore, in the embodiment of lathe 10 according to the invention, a gap swing facility is provided, despite the absence of the traditional arrangement of removable gap piece. This is achieved substantially without loss of slideway support, which normally occurs when a traditional removable gap piece feature is provided, and upon removal. Furthermore, the embodiment of the invention can avoid the loss of accuracy, which is often introduced by non-perfect refitting of a traditional gap piece, after removal for "swing-in gap work". In addition, the length limit imposed by a traditional removable gap piece (to the desirably long and narrow) main guideway is also eliminated, thus giving opportunity to increase this length and consequently provide improved slideway accuracy, rigidity and enhanced wear resistant properties. The three point linear guideway configuration (the carriages 21 and 22 on the front main guide way 17 and the preferably less heavily pre-loaded carriage unit 23 sliding on the rear anti-roll guideway 19) allows for some geometric mis-alignment, thus further improving overall slideway accuracy. Furthermore, the low position of the main guide way 17 relative to the spindle centre line 16, together with the positioning of the lead screw 15 (near the main guideway 17, but between the main guideway 17 and rear guideway 19) causes major cutting forces to be absorbed directly into the main guideway 17, thus promoting maximum load capacity and further enhancing long term accuracy, rigidity and wear resistant characteristics.

Claims: CLAIMS 1. A lathe ( 10) having a lathe bed (11) on which is mounted: (a) a cutting station at which a cutting tool (13) can be mounted: (b) a guide defining a guide path for guiding relative feeding movement between a workpiece holder (14) and the cutting tool (13); and, (c) drive means for relatively moving the workpiece and the cutting tool (13) to engagement with each other; in which the guide comprises three parallel guide elements (17, 18, 19) which are spaced apart from each other and relative to the centre line (16) of the workpiece holder (14) such that a permanent gap or cavity is defined in the lathe bed structure (11) to provide a gap-swing facility and substantially without loss of guide-way support. 2. A lathe according to claim 1, in which the three parallel guide elements comprise a main front guide- way (17), a tailstock bed- way (18), and a rear ante-roll guide- way (19). 3. A lathe according to claim 1 or 2, in which the drive means takes the form of a lead screw arrangement. 4. A lathe according to claim 2, in which the cutting tool (13) is carried by a travelling assembly (12) movable along the guide elements (17, 18, 19), and including two front carriages (21, 22) which are slidable along the main front guide- way (17), and a further carriage unit (23) which is slidable along the rear ante-roll guide-way (19). 5. A lathe according to claim 4, in which the geometry of the arrangement of the guide elements (17, 18, 19), in relation to the centre line (16) of the workpiece holder (14), provides a permanent cavity or gap in the lathe bed (11), and to allow for extra "gap- swing" capability, without loss of slide-way support which inevitably occurs when a traditional gap piece is removed in known designs of lathe. 6. A lathe (10) having a lathe bed (11) - which is mounted: (a) cutting station at which a cutting tool (13) can be mounted: (b) a guide (17, 18, 19) defining a guide path for guiding feeding movement of the cutting tool (13) relative to a workpiece holder (14); and, (c) drive means for advancing the cutting tool (13) into engagement with a workpiece when mounted on said holder (14); in which the lathe (10) excludes provision of a removable gap piece, and in which said guide comprises three parallel guide elements (17, 18, 19) which are spaced apart from each other and relative to the centre line (16) of the workpiece holder (14) such that a permanent gap or cavity is defined in the lathe bed (11) to provide a gap-swing facility and substantially without loss of guide- way support for the movement of the cutting tool. 7. A lathe according to claim 6, including a lead screw arrangement (15) for moving the workpiece and the cutting tool (13) to engagement with each other.

Inventors: BAULK IAN, COOK PETER HENRY, BAULK, IAN, COOK, PETER, HENRY
Applicants: 600 UK LTD, BAULK IAN, COOK PETER HENRY, 600 UK LIMITED, BAULK, IAN, COOK, PETER, HENRY
Application year: 2000
Main classification: B23Q1
IPC codes: B23B3, B23Q1