GB2184678A

GB2184678A - Lathe

Info

Publication number: GB2184678A
Application number: GB08618098A
Authority: GB
Inventors: Miguel A Martinez
Original assignee: Philopatent SA
Current assignee: Philopatent SA
Priority date: 1985-12-30
Filing date: 1986-07-24
Publication date: 1987-07-01
Also published as: FR2592326A1; ES550564A0; ES8702194A1; GB8618098D0

Abstract

The lathe has a fixed horizontal headstock and tailstock (3) and a bed (1) having guides (7) and (8) on which a carriage (2) is mounted for horizontal movement. A tool post (5) with a cutter (6) is mounted on a transverse carriage (11) for transverse movement towards and away from a workpiece guided by a guide (10) on the carriage (2). The toolpost and guide (10) are located to the rear of and above the headstock and tailstock and the guide (10) is inclined downwardly and forwardly so that the cutter attacks the workpiece from the rear upper zone. This improves the accessibility of the machine for the operator and makes it easier for him to observe the cutter during machining. The front face of the bed and guides (7) and (8) are located to the rear of the headstock and tailstock and inclined forwardly and downwardly. This facilitates fall of the chips and their extraction by means of an exhauster of the parallel type or towards the pit of the lathe. The plane through the centre of gravity of the toolpost (5) in its working position, falls between the guides (7) and (8) to increase stability. <IMAGE>

Description

SPECIFICATION Lathe The present invention relates to a lathe of the type having the axes of the headstock a nd the tailstock positioned horizontally.

In general this type of lathe comprises a series of horizontal guides on which a carriage is moved and guided to perform a longitudinal movementand which supports a tool post with meansfortransverse displacement, so that by combining these two movements the cutter can be positioned at any point on theworkpiece, both in the longitudinal direction and at any depth. These two movements are limited by the dimensions of the lathe.

This type of lathe, however, suffers from drawb acks where the arrangement of the guides and the zone of attack of the cutters on the workpiece are concerned, as the former may impede the machining operations while the latter usually attacks the workpiece from the front, thus obstructing the operator's view.

The present invention provides a lathe having a horizontal headstock and having a tool post mounted on guides for transverse movement of the post towards and away from the headstock, in which the guides and post are located at the rear ofthe headstock, the tool post is located above the head and the guides are inclined with respect to the horizontal so that the tool attacks a workpiece from the rear upper zone of the lathe.

Such a lathe improves the accessibility of the machineforthe operator and makes iteasierforhim to observe the cutter during the machining.

Preferably a carriage is mounted on guides on a bed ofthe machine for horizontal longitudinal move ment. The front face ofthis bed and the guides are inclined downwardly and forwardly and are located at the rear of the lathe behind the headstock.

Thefactthatthe longitudinal carriage is guided solely on the bed and the operating mechanisms of the carriage and also the tool post assembly are situated towards the rearzone, would with many arran gements with this type of overhang, subject the machine to an imbalance. The present lathe preferably has the plane containing the centre of gravity of the tool post positioned between the longitudinal guides on the bed.

The longitudinal carriage is preferably triangular in section with oneface corresponding to the inclined front face of the bed which provides increased resistance to the cutting stresses and makes it possibleto operate with a high spindle power even in cases of maximum chip removal.

Oneembodimentoflatheinaccordancewiththe invention will now be described by way of example only with reference to the accompanying drawing in which Figure lisa sectional view, through a vertical plane, of a lathe.

On a bed 1 positioned horizontally and parallel to the main axis of the machine 4 comprising a headstock and a tailstock, a carriage 2 is provided which moves horizontally, being guided on the bed 1 while guides 10 are provided on the carriage 2 for guiding the movement of a second transverse carriage 11 supporting a toolpost 5.

The guides 10 for supporting movementofthe transverse carriage 11 extend in a plane inclined forwardly and downwardly with respect to the horizontal at an angle in the range 42 to 80 degrees so that the cutter6 attacks a workpiecefrom the rear upper zone.

According to a preferred feature of the invention which may be claimed independently, the bed 1 is provided at its front with an inclined face situated far ther back than the vertical plane passing through the axis 4 ofthe machine. By this means, and despite the fact that the workpiece is attacked from the rear, the chips fall in front of the bed and, thanks to the inclination of the front face ofthis latter, can be extracted without difficulty by any type of any parallel exhauster or else directed to the pit of the machine.

The ends of the inclined frontface of the bed 1 are provided with guides 7 and 8forthe movement of the longitudinal carriage 2. The carriage 2 is of triangulartruss section, having one side corresponding with the inclined front face of bed 1. It is thereby renderered highly resistant to the cutting stresses andenablesa high powertobeappliedtothespindle and a maximum rate of chip removal to be obtained.

The longitudinal movementofthecarriage2isef- fected by means of a spindle 9 which at the same time functions as a further guide for the carriage.

This spindle is actuated from one of its ends via a DC motor.

The carriage 11 bearing the tool post 5 is moved by a DC motor 12,this movementtaking place on the guide 10via a spindle 16 located on top of the motor 12 and having its front portion coupled to the motor while its rear portion is integral with an electric brake 13 enabling the transverse movement of the carriage to be stopped. Owing to the weight of the latterthis could not be done in any otherway. The rear portion of the brake 13 is fitted with a " resolver" 1 5 which controls the transverse feed of the cutter for each turn ofthe spindle, thus ensuring considerable accuracy in the feed action.

The tool post 5 includes a set of cutters positioned on a substantially circular tool holder capable of performing pre-selected angular movements under the action of a hydraulic motor 14 cou pled to a rotary position selector.

According to a further preferred feature of the present invention, which may be claimed independently, the tool post 5, particularly during the machining operations, has its centre of gravity in a vertical plane which falls between the g u ides 7 and 8forthe movement ofthe longitudinal carriage 2; as a result, even though the assembly shown in the drawing has the appearance of an overhung structure,this does not exist physically, thanks to the special configuration of the bed and the arrangement of carriage 2.

As already mentioned the front face of bed 1 is in clinedupwardlytowardstherearzone(atan angle in the range 400 to 800). The guides 10 of the transverse carriage are inclined in the same direction. These angles may be equal to each other although the angle formed by the front face of the bed with respect to the horizontal will preferably be greater than that formed by the guide 10.

The front face ofthe bed 1 is also provided with guides 17to enablethetailstock3to be secured by means of screws once it has been positioned as required in order to securetheworkpiece. Thetailstock 3 contains a hydraulic cylinder by which the feed and return movements of the body are effected, the oil return circuit ofthe cylinder being utilised forthe internal lubrication of the complete assembly. The securing guides 17 ofthetailstock3 are also usedforthe installation, by the same system, of a steady restserving to prevent bending during the machining of slenderworkpieces.

The fixed headstock has various speed ranges, and the changeover from one speed range to another is effected automatically by means of a hydraulic cylinderactuated by the numerical control system ofthe machine.

Claims

1. A lathe with a fixed horizontal headstock and having a tool post mounted on guides for transverse movement ofthe post towards and away from the headstock, in which the guides and post are located at the rear of the headstock, the tool post is substanti ally located above the headstock, and the guides are inclined with respect to the horizontal so that the tool attacks a workpiece from the rear upper zone ofthe lathe.

2. A lathe according to Claim 1 having a bed with a frontface inclined downwardly and towards the front and situated to the rear of the headstock.

3. A lathe according to Claim 1 or Claim 2 having a carriage mounted on the bed for horizontal move ment,the carriage being triangular in section with one face corresponding to the front face of the bed.

4. A lathe according to any of Claims 1 to 3 in whichthetool post is mounted on a carriagewhich slides on guides situated in the rear upper part relat iveto the longitudinal axes of the headstock and tail stock.

5. A lathe in accordance with any of Claims 1 to 4 having a bed with guides and a longitudinal movable carriage mounted on the bed for horizontal move mentguided by the guides, in which a planethrough the centre of gravity of the tool post falls between the longitudinal carriage guides.

6. A lathe in accordance with any of Claims 1 to 5 having a bed on which is mounted a longitudinal car riage for horizontal movement, and including a spindle drive means situated in the rear plane ofthe latheforaffecting said horizontal movement.

7. A lathe according to any of Claims 1 to 6 in whichtheanglewhichtheguideforthetransverse movement of the tool post forms relative to the hori zontal is in the range 40"two809.

8. A lathe in accordance with Claim 2 or any Claim dependent thereon in which the angles formed by the front face of the bed and the guide for the transverse movement of the tool post take the same directions but are not equal.

9. A lathe according to Claim 8 in which the angle formed by the front face of the bed is greaterthan that formed by the guide for the transverse movementofthetool post.

10. A lathe according to Claim 2 or any of Claims 3 to 7 as dependent thereon in which the angles formed by the frontface of the bed and the guide for the transverse movement of the tool postarethe same.

11. A lathe substantially as described herein with reference to or as illustrated in the accompanying drawings.