GB1593266A - Chucks for machine tools - Google Patents

Description

(54) CHUCKS FOR MACHINE TOOLS (71) We, WICKMAN MACHINE TOOL SALES LIMITED, a British Company of Banner Lane, Tile Hill, Coventry, CV4 9AD, England do hereby declare the invention for which we pray that a Patent may be granted to us and the method by which it is to be performed, to be particularly described in and by the following statement: This invention relates to machine tools such as lathes and to workpiece holding chucks for such machine tools. A chuck of the kind with which the invention is concerned, is provided with one or more jaws mounted in a body, the jaws being movable normally radially with respect to an axis about which the chuck can rotate, such movement of the jaws being for the purpose of gripping and releasing workpieces. Such a chuck is furthermore of the kind in which actuation is capable of being carried out by remote control, by power means. A chuck of this kind will for convenience be referred to as being of the kind specified.

The object of the invention is to provide a chuck of the kind specified of which the power means for actuation thereof is efficient in operation and is of minimum size especially in the direction of the axis of the chuck.

According to the invention a chuck for a machine tool is provided with a power means whereby it is actuated, said power means comprising a body defining a generally part cylindrical sector shaped cavity therein, the cavity containing a sector shaped member movable through an angle under the influence of fluid under pressure applied thereto, the member controlling a part of the chuck which is movable angularly about the axis of the power means cylinder which causes actuation of at least one jaw of the chuck.

The invention will now be described by way of example with reference to the accompanying drawings in which: Figure I is a diagrammatic view of a multi-spindle automatic lathe incorporating a chuck in accordance with the invention Figure 2 is an enlarged cross sectional view of the chuck and indicating the position of power means whereby the chuck is actuated; Figure 3 is a cross sectional view on the line 3-3 in Figure 4; Figure 4 is a cross sectional view on the line 4-4 in Figure 6.

Figure 5 is an end elevation view in the direction of arrow 5 in Figure 3, Figure 6 is a cross-sectional view on the line 6-6 in Figure 4, Figure 7 is a front elevtion view of the chuck in accordance with the invention seen from the direction of arrow 7 in Figure 2, Figure 8 is a view from the direction of the arrow 8 in Figure 2, and Figure 9 is a cross-sectional view on the line 9-9 in Figure 7.

Referring first to Figure 1 there is illustrated an automatic multi-spindle lathe to which the invention is applicable. This lathe comprises a base 10 on which are two superstructures 11 and 12. These are connected by a bridge structure 13 below which is defined a working space. Rotatably and indexably mounted in the superstructure 11 is a drum 14 in which are a plurality of workspindles each having a workpiece holding chuck 15. Spanning the space between the superstructures 11 and 12 is a shaft 16 which is offset with respect to the axis of indexing of the drum 14.

Tool slides and a tool block are also provided, though these are omitted from Figure 1 for clarity. The tools carried on the slides and block can be advanced to the workpieces to carry out machining operations at the respective stations occupied by the spindles in turn. It is however arranged that at one of the stations the workpieces may be extracted from the associated chuck 15 by a further chuck 17 mounted on an arm 18 which in turn is mounted on the shaft 16.

The arm can swing towards and away from a position in which the chucks 17 and 15 are in alignment and the chuck 17 on its arm 18 may be advanced to a position to accept the workpiece from the chuck 15. Appropriate power operated means are provided for swinging and axial advance of the chuck 17 on its arm 18 and these are also omitted from the drawing for clarity. The chuck 17 is actuated by power means 19 which will be further described.

Referring to Figure 2, this shows on an enlarged scale, the chuck 17 and it also shows the relative position of the power means 19.

Figures 3, 4, 5 and 6 illustrate the power means which will be described first.

The power means comprises a generally cylindrical casing made up from two flanged circular end plates 21, 22 with a spacer ring 23 between them. The spacer ring is of T section and the head of the T engages behind the respective flanges of the end plates 21 and 22, as shown in Figures 3 and 6. Headed bolts 24 secure these parts of the casing together and the heads extend out of the surface of the end plate 21. Each such head has two side flats as shown in Figure 5 and a central tapped hole.

Within the cylindrical space defined in the casing there is secured a fixed segmental part 25 of which the included angle is approximately 225". This is secured in place, so as completely to fill a proportion of the cylindrical space, by dowels 26 and bolts 27.

Within this segmental part 25 drillings 28 are provided which communicate with the respective radial surfaces formed on the segmental part 25. Each such drillings 28 communicates with a drilling 29 which is provided in the end plate 22.

Also mounted within the cylindrical space in the casing and occupying the space between the radial surface of the segmental part 25 is a segment shaped piston 31 of which the included angle is approximately 85". This piston is secured by bolts 32 and a dowel 33 to a cylindrical sleeve 34 occupying the centre of the casing. The sleeve has an internal keyway 35.

A hollow cylindrical externally threaded spigot 36 is formed on the end plate 22 of the casing. Surrounding this is a circular flat disc 37 having an integral bracket portion.

The bracket portion incorporates a tubular extension 38 through which passes a radial stud 39 carrying a lock nut 41. The stud extends into the exterior of the tubular extension 38 to lock in a recess formed in a spindle 42. The spindle is carried by the arm 18 which is indicated generally in Figure 6.

The spindle furthermore has annular grooves 43 communicating with drillings (not illustrated) through the spindle 42.

These grooves 43 also communicate with a pair of cross drillings 44 through the tubular extension 38 and opening into respective concentric annular grooves 45 in the face of the disc 37 presented away from the tubular extension 38. These grooves 45 communicate with respective ones of the drillings 29 in the disc 22 of the casing to provide supply and return passages for hydraulic fluid. This fluid can enter or escape from the respective spaces defined between the radial surfaces of the segmental part 25 and of the segment shape piston 31. Application of such pressure causes the piston 31 to swing angularly about the axis of the sleeve 34 to which it is attached, thus imparting rotation through appropriate angle to that sleeve 34.

To secure the disc 37 in place on the spigot 36 a lock nut 46 is provided.

The chuck is shown in Figures 2, 7, 8 and 9 which will now be described. The chuck includes a generally cylindrical member 51.

This is fixed by means of bolts 52 to the heads of the bolts 24 of the power means.

Compression springs 50 surrounding the bolts 52, provide a degree of flexibility between the chuck and the power means. A covering sleeve 53 is provided to enclose the mechanism between the chuck and power means.

In the face of the cylindrical member 51 presented away from the power means 19, a diametral T-slot 54 is provided to accommodate a pair of workpiece gripping jaw members 55, 56. These are provided with respective pairs of holes 57 to accommodate bolts whereby gripping jaws proper can be attached. Extending through radial slots 58 in the member 51 are pegs 59 which engage in central holes in the members 55 and 56 respectively. Radial movement of these pegs 59 result in corresponding radial movement of the members 55 and 56 respectively to permit gripping and releasing of workpieces. The pegs are guided in slots 58 by flattened portions 59a.

In the opposite side of the member 51 is defined a cylindrical recess 61 in which is rotatably mounted a cam plate 62. To retain this within the recess there is an annular cover 63 secured to the member 51 by bolts 64.

In the centre of the cam plate 62 is secured a hollow flanged spindle 65 which is secured and located with respect to the cam plate 62 by bolts 66 and a dowel 67. A key 68 in the exterior of the spindle 65 engages in the keyway 35 within the cylindrical sleeve 34 of the power means into which the spindle 65 extends.

The cam plate has, in this example, four identical arcuate slots 69 at equi-angularly spaced positions around the centre. The arcuate slots 69 however are not concentric with the axis but one end of each is closer to the centre. All four slots are identically oriented with respect to the centre. Occupying two of the slots 69 are rollers 71 carried on the ends of the respective pegs 59.

If the spindle 65 is rotated through the power means 19, the cam plate 62 is also rotated. Rotation is confined to the angle subtended by each of the slots 69 in the cam plate and the relative radial distances of the ends of the slot define radial movement of the pegs 59 in their slots 58. The radial movement of the pegs 59 is accompanied by a corresponding movement of the jaw members 55.

The member 51 of the chuck is provided with arcuate recesses 72 which are merely provided for reducing the weight of the assembly.

The axial length of the chuck and power means together is very small and enables a power operated chuck to be used in a very confined space.

Though the chuck and power means have been described in relation to the transfer arm 18 in the machine shown in Figure 1 such chuck and power means combination may however be used in place of the chuck 15 in the drum 14 or in any other appropriate apparatus.

The chuck and power means can be used on any conventional type of machine tool and the chuck can use one or more jaws, as required, by providing appropriate cam plates and associated parts. Furthermore, the jaws may be unequally spaced.

The chuck excluding the power means is claimed in Patent Application No. 43481/76 (Serial No 1593265) WHAT WE CLAIM IS: 1. A chuck for a machine tool provided with a power means whereby it is actuated, said power means comprising a body defining a generally part cylindrical sector shaped cavity therein, the cavity containing a sector shaped member movable through an angle under the influence of fluid under pressure applied thereto, the member controlling a part of the chuck which is movable angularly about the axis of the power means cylinder which causes actuation of at least one jaw of the chuck.

2. A chuck as claimed in claim 1 in which the part cylindrical sector shaped cavity is formed in a body having entry and escape passages for fluid under pressure whereby the sector shaped member is movable.

3. A chuck as claimed in claim 1 or claim 2 wherein the sector shaped member is connected to a control shaft arranged to engage with the chuck.

**WARNING** end of DESC field may overlap start of CLMS **.

Claims (3)

**WARNING** start of CLMS field may overlap end of DESC **. arcuate slots 69 however are not concentric with the axis but one end of each is closer to the centre. All four slots are identically oriented with respect to the centre. Occupying two of the slots 69 are rollers 71 carried on the ends of the respective pegs 59. If the spindle 65 is rotated through the power means 19, the cam plate 62 is also rotated. Rotation is confined to the angle subtended by each of the slots 69 in the cam plate and the relative radial distances of the ends of the slot define radial movement of the pegs 59 in their slots 58. The radial movement of the pegs 59 is accompanied by a corresponding movement of the jaw members 55. The member 51 of the chuck is provided with arcuate recesses 72 which are merely provided for reducing the weight of the assembly. The axial length of the chuck and power means together is very small and enables a power operated chuck to be used in a very confined space. Though the chuck and power means have been described in relation to the transfer arm 18 in the machine shown in Figure 1 such chuck and power means combination may however be used in place of the chuck 15 in the drum 14 or in any other appropriate apparatus. The chuck and power means can be used on any conventional type of machine tool and the chuck can use one or more jaws, as required, by providing appropriate cam plates and associated parts. Furthermore, the jaws may be unequally spaced. The chuck excluding the power means is claimed in Patent Application No. 43481/76 (Serial No 1593265) WHAT WE CLAIM IS:

1. A chuck for a machine tool provided with a power means whereby it is actuated, said power means comprising a body defining a generally part cylindrical sector shaped cavity therein, the cavity containing a sector shaped member movable through an angle under the influence of fluid under pressure applied thereto, the member controlling a part of the chuck which is movable angularly about the axis of the power means cylinder which causes actuation of at least one jaw of the chuck.

2. A chuck as claimed in claim 1 in which the part cylindrical sector shaped cavity is formed in a body having entry and escape passages for fluid under pressure whereby the sector shaped member is movable.

3. A chuck as claimed in claim 1 or claim 2 wherein the sector shaped member is connected to a control shaft arranged to engage with the chuck.