GB2178991A

GB2178991A - Machine tool having two spindles

Info

Publication number: GB2178991A
Application number: GB08619386A
Authority: GB
Inventors: Christopher John Mo Southworth
Original assignee: TI MACHINE TOOLS Ltd
Current assignee: TI MACHINE TOOLS Ltd
Priority date: 1985-08-13
Filing date: 1986-08-08
Publication date: 1987-02-25
Also published as: GB8619386D0; GB8520268D0

Abstract

A machine tool having two spindles 1, 10, each arranged to be driven for rotation about a common axis and each having a chuck 5, 5' or other work-holding device facing each other and spaced apart along the common axis. The machine tool also has tool-holding devices such as turrets 7, 16 associated with the respective spindles 1, 10 and arranged to be positioned for working on a workpiece held in the respective chuck 5, 5'. The second spindle 10 is movable transversely of said common axis to either side thereof in directions Y2 and also in directions Z2 parallel to the common axis, whereby a workpiece held in one of the chucks 5, 5' can be transferred directly to the other chuck. <IMAGE>

Description

SPECIFICATION Machine tool having two spindles The invention relates to a machine tool having two spindles.

According to the invention, a machine tool comprises two spindles, each arranged to be driven for rotation about a common axis and each having work-holding means facing each other and spaced apart along the common axis; tool-holding devices associated with the respective spindles and arranged to be positioned for working on a workpiece held in the respective work-holding means, and means for effecting movement of the second spindle transversely of said common axis to either side thereof and in directions parallel to said common axis, whereby a workpiece held in one of the work-holding means can be transferred directly to the other work-holding means.

The machine tool provided by this invention therefore enables a workpiece to be machined first while held in the work-holding means of one spindle and then to be machined while held in the work-holding means of the other spindle. This enables one end of a workpiece to be finish machined while held by the other end in the work-holding means of the first spindle and then said other end of the workpiece to be finish machined while held by said one end in the work-holding means of the second spindle. The machine tool provided by this invention also enables simultaneous machining of two workpieces to occur.

Thus said one end of a second workpiece can be machined while held in the work-holding means of the first spindle while said other end of a first workpiece is machined while held in the work-holding means of the second spindle, said one end of the first workpiece having already been machined when held in the work-holding means of the first spindle.

Preferably, the first spindle is fixed with respect to movement along the common axis of the two spindles and the second spindle is mounted for bodily movement on guide-ways extending parallel to the common axis toward and away from the first spindle.

The tool-holding means may be multi-station turrets mounted back-to-back and arranged to be indexed independently of each other. Each turret may be mounted for movement in directions perpendicular to the common axis of the spindles. The turret associated with the first spindle may additionally be movable in directions parallel to the axis of rotation of the first spindle and so the relative movement between each spindle and its associated turret are in two orthogonal directions (Z and X).

The first spindle may have means for effecting its operation in a closed position loop (C- axis). The second spindle may also have means for effecting locking of the spindle, whereby by appropriate relative movement between the associated turret and spindle slideways in a required combination of the X, Y and Z axes and the use of appropriate powered tools in the respective turret contour generation can be effected.

The turrets may carry any desired arrangement of fixed tools, such as turning tools or boring bars, and powered tools.

Workpieces or bar may be introduced to the first or primary spindle by, for example, gantry or robot or a bar-feed system. Finished workpieces may be removed from the second or secondary spindle by, for example, gantry, robot or work-catcher.

By way of example, a machine tool having two spindles is now described with reference to the accompanying diagrammatic side view of the machine tool.

Referring to the drawing, the machine tool comprises a primary spindle 1 driven for normal turning and boring operations by a motor 2 through a pulley and belt system 3. The facility may be provided whereby the main motor 2 is disengaged and the primary spindle 1 is driven in a closed position loop by a servo-motor 4. This is known as "C- axis" operation.

The component 5 to be machined is held in the chuck 6. The component may be a separate workpiece or be supplied as a bar by a bar-feed system (not shown).

The first or primary spindle 1 is fixed in position on the bed of the machine tool and is associated with a tool-holding system comprising a multi-position turret 7 on which various tools 20 for turning and boring operations may be mounted, as desired. Powered tools may be fitted to the turret 7. These are not shown; but are similar to powered tools 19 to be mounted on a right-hand turret 16, to be described hereinafter.

The turret 7 is mounted on slides and slideways 21 providing for movement of the turret relatively to the spindle 1 parallel to the spindle axis (the Z, direction).

The slides of the turret 7 may be driven by motors, for example, servo-motors through ball screws in position loop control.

The second, i.e, the secondary, spindle 10 shown at the right-hand side of the drawing is mounted on a carriage 9 mounted on slideways 8 parallel with the axis of rotation of the primary spindle 1 and the Z1 slideways for movement in the Z2 direction toward and away from the primary spindle 1. The carriage 9 is driven on the slideways by a servo-motor and ballscrew, or by another suitable means. The secondary carriage 9 carries the secondary spindle 10 which can be rotated and angularly positioned by a motor 11 through a belt drive system 12. The spindle 10 carries the secondary chuck 13.With the axis of the secondary spindle co-axial with the axis of the primary spindle 1, the secondary spindle 10 can be moved bodily in the Z2 direction toward the primary chuck 6, whereby with both spindles stopped, the workpiece can be transferred directly from the chuck 6 to the chuck 13 and then returned in the chuck 13 on the slideways 8 to the position 51. The opening and closing of the two chucks 6 and 13 is controlled independently by conventional methods, for example, rotatable hydraulic cylinders 15 and 14 respectively.

Although the word "chuck" has been employed, it should be understood that the chucks 6 and 13 may be any work-holding devices.

A second set of tooling is provided for use on the workpieces held in the chuck 13 and comprises a second multi-position turret 16 arranged to carry various tools for turning and boring and also powered tools 19 for, for example, drilling and milling operations. The turret 16 is mounted back-to-back with respect to the turret 7 and is arranged to be moved on a slide-way system 17 in the direction X2, perpendicular to the spindle axis.

The secondary spindle may also be provided with a facility to move in the third orthogonal direction, indicated by arrows Y2 to either side of a central position in which the axis of the spindle 10 is co-axial with the axis of the spindle 1. This facility is provided by a transverse slide and slideway 23 and the slide is powered by a motor and a ball-screw drive 18.

The primary spindle 1 together with the turret 7 constitutes a 2 - axis lathe with full interpolation between the X, and Z axis. Thus all standard turning, boring and threading operations can be performed.

The C- axis facility with appropriate control functions enables interpolation between C and X1, C and Z1, and C and both X1 and Z1 to be possible.

The secondary spindle 10 together with the turret 16 can be used with many types of control system. Thus linear motion and linear interpolation between X2, Z2 and Y2 axes can be achieved. With the spindle locked the X2, Z2 and Y2 axes can be used for contour generation. C- axis control of the spindle 10 may be used for component inspection.

The provision of the two spindles 1 and 10 and the respective turrets 7 and 16, or other respective tool-holding systems enables a workpiece to be machined first in the chuck 6 and then in the chuck 13. In particular, the right-hand end of the workpiece can be finish machined while the workpiece is being held in the chuck 6 in the position 5. Then the left-hand end of the same workpiece can be finish machined, including contour generation, if required, while the workpiece is being held by its right-hand end in the chuck 13 in the position 5'. Furthermore a first workpiece, which had previously been machined at its right-hand end while being held in the chuck 6 may be machined at its left-hand end while being held in chuck 13 simultaneously with the machining of a second workpiece being held in chuck 6.This therefore simplifies and saves machining time and avoids the need for two separate machine tools.

Another advantage of the machine tool described herein is that direct transfer of a workpiece from the chuck 6 to the chuck 13 is effected by stopping both spindles and advancing the spindle 10, when aligned co-axially with the spindle 1, along the slideways 8 in the Z2 direction, so as to bring the chuck 13 close to the chuck 6. The right-hand end of the workpiece is then engaged by the chuck 13 and then the chuck 6 is disengaged from the left-hand end of the workpiece and the spindle 10 is then returned on the slideways 8 to the position shown in the drawing. The opening and closing of the chucks to transfer the workpiece may be performed, for example, by the hydraulic cylinders 14 and 15.

Workpieces may be introduced to the chuck 6 by any convenient way, for example, a bar-feed system, a gantry or robot, and may be removed from the chuck 13 by any convenient way, for example, a workcatcher, a gantry or robot.

Claims

1. A machine tool comprising two spindles, each arranged to be driven for rotation about a common axis and each having a work-holding means facing each other and spaced apart along the common axis; tool-holding devices associated with the respective spindles and arranged to be positioned for working on a workpiece held in the respective work-holding means, and means for effecting movement of the second spindle transversely of said common axis to either side thereof and in directions parallel to said common axis, whereby a workpiece held in one of the work-holding means can be transferred directly to the other work-holding means.

2. A machine tool as claimed in Claim 1 in which the first spindle is fixed with respect to movement along the common axis of the two spindles and the second spindle is mounted for bodily movement on guide-ways extending parallel to the common axis toward and away from the first spindle.

3. A machine tool as claimed in Claims 1 and 2 in which either or each tool-holding means is a multistation turret.

4. A machine tool as claimed in Claim 3 having two multi-station turrets mounted back-to-back and arranged to be indexed independently of each other.

5. A machine tool as claimed in Claim 3 and 4 in which the or each turret is mounted for movement in directions perpendicular to the common axis of the spindles.

6. A machine tool as claimed in Claim 5 in which the turret associated with the first spindle is additionally movable in directions parallel to the axis of rotation of the first spindle.

7. A machine tool as claimed in any preceding claim in which the first spindle has means for effecting its operation in a closed position loop.

8. A machine tool as claimed in any preceding claim in which the second spindle has means for effecting locking of the spindle and including means for effecting relative movement between the associated tool-holding means and said second spindle in any desired combination of three orthogonal axes of movement, whereby contour generation can be effected.

9. A machine tool as claimed in any of Claims 3-6 in which the or each turret is arranged to carry any desired arrangement of fixed or powered tools.

10. A machine tool as claimed in any preceding claim in which the tool-holding devices are any suitable type of chuck.

11. A machine tool as claimed in any one of Claims 1-9 in which the tool-holding device of the first spindle is of the type to receive a bar and is associated with a bar-feed system.

12. A machine tool as claimed in any preceding claim in which the second spindle is associated with a work-catcher device.

13. A machine tool constructed and arranged substantially as described herein and shown in the accompanying drawing.