MACHINE TOOL

Abstract: A machine tool has a table (14) movable relative to a headstock (11) for machining a workpiece (16) mounted on the table (14) by a tool (25) mountable on a spindle (12) provided on the headstock (11). The table (14) also supports a magazine (17) for blank workpieces (16A), and the table (14) is movable between a first position in which the work­ piece (16) and the tool (25) are in machining proximity and a second position in which the headstock (11) and the mag­ azine (17) are proximate. The headstock (11) has a work­ holder (31) adapted to grip a blank workpiece (16A) at said second position for transfer, by movement of the table (14), to said first position. After machining, the workpiece (16) is correspondingly returnable to the magazine (17). The work holder (31) is provided on the headstock (11) separately from the spindle (12).

Description: BACKGROUND TO THE INVENTION This invention relates to machine tools, and more specifically to the transferring of work pieces between a location where the workpieces are stored and a location where the workpieces are to be machined according to the preamble of claim 1. It is known from GB-A-1263912 to provide a machine tool comprising a headstock supporting a spindle on which a chuck is supported. The headstock is movable between one pallet on which workpieces are stored and another pallet on which tools are provided, so that a workpiece received by the chuck when adjacent to one pallet can be transferred to proximity with the other pallet for machining. Such an arrangement has the difficulty that if the machining is to be done by a tool to be provided on the spindle, the chuck has to be removed and a tool has to be provided on the spindle before machining can commence. The above difficulty is reduced or overcome by the invention as claimed herein. BRIEF DESCRIPTION OF THE DRAWINGS Preferred embodiments of a machine tool according to this invention will now be described, by way of example, with reference to the accompanying drawings wherein:- Fig.1 is a front elevation of a first embodiment of the machine tool, Fig.2 is a plan view of Fig.1 drawn diagrammatically and to a reduced scaled, and Fig.3 is a view similar to Fig.2 but showing a second embodiment. DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS Referring to Figs.1 and 2, the machine tool comprises a head 10 supported on a first support member or headstock 11 by a spindle 12. The spindle 12 is supported for rotation in an arbor 32 and is rotatable by a motor MR12 about an axis 12A. The arbor is movable in the direction of the axis 12A, i.e. in the Z-direction, by a motor MZ12. The headstock 11 is secured to a bed 13 and is movable relative thereto in the Y-direction by a motor MY11. A second support member or table 14 is supported on the bed for movement in the X-direction and is movable in that direction by a motor MX14. The head has releasably secured thereto the work holder 15 having a tapered spigot 26 for engagement with the head 10. The work holder is operable by a motor M15, acting through an operating rod 29, to grip or release a workpiece 16. The table 14 comprises two parts being respectively a machining support 18 and a storage support or magazine 17. The magazine 17 supports a plurality of workpiece blanks 16A. The support 18 has secured thereto a tool mount 19 to which is secured at least one turning tool 19A, a dividing head 21 operable by motors M21 and supporting a chuck 20 operable by a motor M20 for gripping and releasing a workpiece. The support 18 also embodies a tool storage magazine 22 releasably supporting at least one milling tool 23. The tool 23 has at one end a milling cutter 25 and at the other end a spigot 24 dimensioned for being gripped by the holder 15. The table 14 also contains a holder 27 for reversing a said workpiece end-to-end and operable by a motor M27. The table 14 constitutes a common structure for the supports 17,18,22. The machine tool is operated by a numerical control system 40 programmed to act on the motors, generally referred to by the letter M, in a predetermined sequence comprising the following operations: 1. Moving the head 10 and the bed 14 relative to one another (motors MY11,MZ12,MX14) to bring the holder 15 into register with one of the blanks 16A in the magazine 17. 2. Gripping the blank 16A (Motors MZ12,M15). 3. Moving the head 10 into proximity with the tool 19A (Motors MY11,MZ12,MX14). 4. Rotating the spindle 12 (Motor MR12) to rotate the blank 16A relative to the tool 19 for a turning operation. 5. Moving the head and the bed relative to one another (Motors MZ12,MX14) to provide for feed and depth of cut in said turning operation. The system 40 is further programmed, on completion of the above turning operation, to return the workpiece 16 to the magazine 17 and repeat the cycle for the next blank. The system 25 may be programmed to perform a milling operation by moving the head 10 to insert the workpiece 16 into the chuck 20 operating the chuck motor M20 to grip the workpiece, moving the head 10 to the tool 23, operating the holder 15 to grip the tool 23, moving the head 10 to move the tool 23 to the workpiece 16 held in the chuck 20, and rotating the spindle 12 and moving the head 10 to carry out the milling operation. Means may be provided for automatically releasing the holder 15 from the head 10 and securing it thereto. To this end the motor M15 may be adapted to engage the narrow end of the tapered spigot 26 of the holder 15 and draw the spigot into a receiving socket in the head, the motor acting through the intermediary of the rod 29. Apparatus for automatically securing a work holder or a tool holder to a spindle and releasing it therefrom, and further comprising means for automatically operating the work holder to grip and release a workpiece, is shown in my/our British Patent Application No. 8206951 and European Patent Application No.83301333.7. The tool 23 may be adapted to be released and secured to the head 10 in the same way as the holder 15, the spigot 23 then being tapered in the same way as the spigot 26. The system may be programmed to move the head 10 to deposit the holder 15 in a storage socket 28 on the work support 17 and pick up the tool 23 for the latter to take the place of the holder 15 in the head 10. In a modification, also shown in Fig. 1, an arbor 30 is supported on the headstock 11 for movement toward and away from the table 14 by a motor M30. The arbor 30 has at one end a gripper 31 operable by a motor M31 to grip or release a workpiece. In operation, the workpieces are transferred between the magazine 17 and the chuck 20 by means of the gripper 31, the spindle 12 being used for supporting a tool, e.g. the tool 23, either in the holder 15 or by means of a spigot such as 26. The arbor 30 and gripper 31 can be a relative light structure compared to the spindle 12 which has to sustain the machining forces. In the embodiment shown in Fig. 3, a magazine 117 and a maching support 118 are stationary, and a headstock 111 is movable on a track 113 along the magazine 117 and support 118 for the purpose of transferring workpieces therebetween. The magazine 117 can be arranged to include a tray or palette containing the workpieces and being removable from a supporting surface of the magazine. Also the support 118 can be to some extent movable relative to the magazine for the purpose of machining operations. However essentially, i.e.for the purpose of the transfer operation, the magazine and the support 118 are stationary.

Claims: Machine Tool comprising a) a headstock (11), b) a spindle provided on the headstock (11), c) first workholding means (15,31) provided on the headstock (11) and operable for gripping or releasing a workpiece (16), d) a machining support (18), e) a storage support (17), f) moving means (13,14,MX14,MY11,MZ12) for relatively moving the headstock (11) between positions respectively adjacent to the storage support (17) and the machining support (18) for transfer of the workpiece (16) therebetween, characterized in that g) the first workholding means (31) is provided on the headstock (11) separately from said spindle (12), h) a second workholding means (20) is provided on the machining support (18) and is operable for gripping or releasing the workpiece (16), i) each said workholding means (31,20) is provided with means (M31,M20) for being operated automatically, and j) means (40) is provided for automatically operating each said workholding means (31,20) for said transfer of the work piece (16). Machine tool according to claim 1 wherein the first workholding means (31) comprise a gripper (31), and automatically operable means (30,M30) supporting the gripper (31) on the headstock (11) for movement in a direction towards and away from the machining support (18).

Inventors: MCMURTHY, DAVID ROBERTS
Applicants: RENISHAW PLC
Application year: 1983
Main classification: B23Q7
IPC codes: B23Q39, B23Q3, B23Q7, B23B11, B23Q1