GB2167325A - Multi-spindle machining centre - Google Patents

Abstract

A machining centre comprises a tool head 9 having four horizontal spindles 12 and movable in three mutually perpendicular axes. The tool head 9 travels between an operating location at a workpiece holder 14 and a tool changing location at a tool magazine 21 above the workpiece holder. The tool magazine 21 has two or more faces containing sets of tools 28 for the tool head and can be rotationally indexed between working and loading positions so that one face can be loaded whilst another is in use. The workpiece holder 14 also has two or more workpiece holding faces and is similarly indexable. <IMAGE>

Description

SPECIFICATION Multi-spindle machining centre Multi-spindle machining centres allow a particular machining operation to be performed simultaneously on a number of identical workpieces.

A number of these machines are currently available but in general they are dedicated machines intended for producing only one kind of component. They also tend to be rather expensive so that even where fairly large numbers of identical components are required it is seldom worthwhile investing in such a machine.

The present invention is intended to satisfy the requirement for a multi-spindle machining centre which can be manufactured at a comparatively low price, and has a layout which is both economical on floor space and which allows the equipment to be adapted to operate on a variety of different workpieces without standing idle for long periods.

According to the present invention there is now proposed a machining centre comprising: -a tool head provided with substantially horizontal spindles for at least two tools, the tool head being movable in three mutually perpendicular axes and being arranged to travel between an operating location and a tool changing location; -a workpiece holder for holding at least two workpieces in a fixed position to enable them to be worked upon simultaneously by the said tools when the tool head is in its operating location; and -a tool magazine for containing sets of tools which the tool head can pick up and set down when in its tool changing location.

With such an arrangement the major precision movements normally to be found in machines of this kind, namely machining and tool changing, can be achieved by a single drive system, thus enabling the overall cost and size of the machine to be reduced. The workpieces can be changed over whilst the tool head is at the tool changing location, and the tools stored in the magazine can be changed over whilst the tool head is machining.

A much preferred and particularly advantageous arrangement is to have the tool magazine indexable between a working position in which the tool head can pick up and set down the tools, and a loading position in which the tools can be manually loaded and unloaded from the magazine.

Rotational indexing is preferred since it tends to result in a more compact layout than could be achieved with linear indexing. Rotational indexing about a long axis of the magazine is particularly preferred in this respect.

The magazine preferably has two or more loadable faces, one of which is in the loading position whilst another is in the working position. Thus, tools can be loaded into one face whilst the tools loaded into the other face are being used.

The tools are preferably arranged in the magazine in groups, each group containing the tools for one driven spindle of the tool head.

In this way loading mistakes are less likely to occur and tool changing can be achieved quickly since the amount of travel required between setting down one set of tools and picking up another is minimised.

The tool magazine is preferably located above the workpiece holder since this takes up less floor space and raises the magazine clear of swarf and other debris produced by machining.

Preferably the spindles are forwardly directed, and when the tool head is in its operating location the workpiece holder is Positioned between the tool head and an operator's location.

The workpiece holder is preferably rotationally indexable between a working position in which the workpieces are presented to the tool head, and a loading position in which the workpieces are presented to the operator's location for loading and unloading. Indexing is preferably carried out in 900 increments so that three different faces of the workpieces are presented to the tool head. The workpiece holder preferably has two or more workpiece holding faces, one of which is presented to the operator whilst another is presented to the tool head.

The tool head is preferably mounted for substantially vertical movement on a tower structure which is itself mounted for movement in one substantially horizontal direction on a carriage which is in turn mounted for movement in another, mutually perpendicular substantially horizontal direction.

The invention will now be exemplified with reference to the accompanying drawings, in which: Figure 1 is a side view, partly in section, of a machining centre, Figure 2 is a front view of the machining centre, and Figure 3 is a plan view of the machining centre.

Referring to Fig. 1, the machining centre comprises a base 1 towards the back of which is mounted a rear frame 2. A carriage 3 is supported by standard tracks 4 and roller bearings 5 on the rear frame for lateral movement, and a tower structure 6 is mounted on the carriage 3 by similar tracks 7 and bearings 8, permitting the tower to move forwardly and rearwardly.

A counterbalanced tool head 9 is mounted on the tower for vertical movement by means of tracks 10 and bearings 11. The tool head has four parallel spindles 12 a-d (Fig. 3) each driven by a respective motor 13 a-d. The spindles are all horizontally aligned and are forwardly directed towards an indexable workpiece holder 14.

Movement in each of the three mutually perpendicular axes is achieved by three servodriven ballscrews 15, only one of which is shown (Fig. 1).

At the front of the base 1 is mounted a forward frame 16. The workpiece holder 14, comprising a transverse beam 17 (Fig. 2) has each end mounted on indexing trunnions 18, 19, supported by the forward frame 16. Each of the four side faces of the beam 17 is provided with four workpiece clamping locations 20 a-d, the layout of which corresponds to that of the spindles 12 a-d. The beam may be rotationally indexed about its horizontal axis permitting any of the four faces to be brought into a working position presented to the spindles, the opposite face being brought into a loading position presented to an operator's location OP in front of the equipment (Fig. 1).

A tool magazine 21, which is also rotationally indexable about a horizontal axis, is mounted above the workpiece holder 14. The ends of the magazine have shafts 22, 23 mounted in bearings 24, 25, and the shaft 23 is coupled to a wheel 26 by which the magazine can be manually rotated. A plunger 27 permits the magazine to be locked in position.

The front and rear faces of the magazine 21 each have provision for loading with fifteen sets of tools 28. Each set of tools consists of four identical tools, one for each spindle. The tools are arranged in four groups 29 a-d, each group containing the tools for one spindle, and each set of tools is arranged in a layout which corresponds to that of the spindles 12 ad.

Beneath the workpiece holder 14 there is a conveyor 30 for carrying away swarf and other debris to a bin 31 (Fig. 2). Chutes 32 channel falling debris towards the conveyor 30.

The electrical control circuitry for the machine is housed in a cabinet 33 located at the rear of the equipment. Programming and monitoring is carried out through an operator's control console 34 located at the side of the machine.

With the tool head 9 positioned in an operating location behind the workpiece holder 14, as shown, the same machining operations can be carried out simultaneously on up to four identical workpieces held on the rear face of the beam 17. Cross feed (x axis) is achieved by movement of the carriage 3 along the tracks 4, vertical feed (y axis) by movement of the tool head 9 along tracks 10, and in feed (z axis) by movement of the tower 6 along tracks 7. While one set of workpieces is being machined the operator is able to set up four further workpieces on the front face of the beam after removing any previously machined workpieces from that face.

Once all the required machining has been done with one set of tools, the tool head moves upwards on tracks 10 into a tool changing location in front of the tool magazine 21. The tool head then deposits the tools in the appropriate positions in the magazine and picks up a new set as required. The head then returns to the operating location to carry out the appropriate operations on the workpieces using the new tools. A complete tool change takes only 20 seconds.

The workpiece holder 14 is then indexed through 900 so that the machined workpieces come to lie on the underside of the beam and a new set of blank workpieces is presented to the spindles. The workpieces can also be machined when they are lying on the top and bottom faces of the beam, thus enabling three different faces of the workpieces to be machined without having to re-clamp them in a different orientation.

If it is required to effect a complete tool change, for example to enable a completely different sequence of machining operations to be performed on a different batch of workpieces, the plunger 27 is released and the magazine is indexed through 1800 by handle 26 so that the new sets of tools loaded into the front face of the magazine are brought into a working position in which they are presented to the tool head. The old tools can then be removed from the magazine and the next set of tools loaded from the operator's location whilst the machine is in operation.

If required, the effective capacity of the magazine can be increased by providing automated indexing of the magazine 21 so that tools loaded into both the front and rear faces of the magazine can be brought into use.

Examples of the kinds of machining operations that could performed with the appropriate tools loaded into the magazine are drilling, milling, tapping, reaming and boring.

The layout of the machine uses a minimum amount of floor space, permits efficient tool and workpiece changing and allows the equipment as a whole to be easily maintained.

Swarf clearance is also very good with the tool magazine being positioned substantially clear of any contamination problems.

The beam 17 could be provided with workpiece clamping locations on only two opposite faces, or it could be triangular with three clamping faces. It could also have more than four clamping faces. Similarly the tool magazine 21 could have three, four, five or more faces into which tools can be loaded.

Although a tool head having four driven spindles is described above, the head could be provided with any number from two upwards. The number and layout of workpiece clamping locations provided on the workpiece holder 14, and of tool groups for which the tool magazine has provision, would of course be adjusted accordingly.

Claims (17)

1. A machining centre comprising: -a tool head provided with substantially horizontal spindles for at least two tools, the tool head being movable in three mutually perpendicular axes and being arranged to travel between an operating location and a tool changing location; -a workpiece holder for holding at least two workpieces in a fixed position to enable them to be worked upon simultaneously by the said tools when the tool head is in its operating location; and -a tool magazine for containing sets of tools which the tool head can pick up and set down when in its tool changing location.

2. A machining centre according to Claim 1, in which the tool magazine is indexable between a working position in which the tool head can pick up and set down the tools, and a loading position in which the tools can be manually loaded and unloaded from the magazine.

3. A machining centre according to Claim 2, in which the tool magazine is rotationally indexable between the two positions.

4. A machining centre according to Claim 3, in which the tool magazine is rotationally indexable about a long axis.

5. A machining centre according to Claim 4, in which the rotational axis of the tool magazine is substantially horizontal.

6. A machining centre according to any of Claims 2 to 5, in which the tool magazine has two or more loadable faces, one of which is in the loading position whilst another is in the working position.

7. A machining centre according to any preceding claim, in which the tools are arranged in the magazine in groups, each group containing the tools for one driven spindle of the tool head.

8. A maching centre according to any preceding claim, in which the tool magazine is located above the workpiece holder.

9. A machining centre according to any preceding claim, in which the spindles are forwardly directed, and when the tool head is in its operating location the workpiece holder is positioned between the tool head and an operator's location.

10. A machining centre according to Claim 9, in which the workpiece holder is rotationally indexable between a working position in which the workpieces are presented to the tool head, and a loading position in which the workpieces are presented to the operator's location for loading and unloading.

11. A machining centre according to Claim 10, in which the workpiece holder is indexable in 900 increments.

12. A machining centre according to claim 10 or 11, in which the workpiece holder has two or more workpiece holding faces, one of which is presented to the operator whilst another is presented to the tool head.

13. A machining centre according to Claim 10, 11 or 12, in which the workpiece holder is indexable about a long axis.

14. A machining centre according to Claim 13, in which the rotational axis of the workpiece holder is substantially horizontal.

15. A machining centre according to any preceding claim, in which the tool head is mounted for substantially vertical movement on a tower structure which is itself mounted for movement in one substantially horizontal direction on a carriage which is in turn mounted for movement in another, mutually perpendicular substantially horizontal direction.

16. A machining centre comprising any novel feature or novel combination of features described above and/or shown in the drawings.

17. A machining centre which is substantially as described above with reference to the drawings.