MACHINE FOR OPERATING PROGRESSIVELY UPON SELECTED SURFACE PORTIONS OF WORKPIECES

MACHINE FOR OPERATING PROGRESSIVELY UPON SELECTED

SURFACE PORTIONS OF WORKPIECES

This invention is concerned with improvements in or relating to a machine for operating progressively upon selected surface portions of wor pieces comprising a work support for supporting a workpiece with a surface thereof, at least one selected portion of which is to be operated upon, exposed, a tool support for supporting a tool which is to operate upon the selected surface portion(s), motor means for effecting relative movement between the work support and the tool support in directions extending lengthwise, widthwise and heightwise of such workpiece surface portion whereby to cause such tool to operate progressively along, a tool mounting, on which such tool is mounted, said mounting being supported by the tool support for heightwise movement relative thereto, and height control means for controlling the heightwise position of the tool mounting, and thus of the tool mounted thereon, in relation to the tool support.

One such machine is described in EP-A-0 079 695, in which machine the tool support supports two tools, side-by-side and each in the form of a rotary radial wire brush, for performing a roughing operation progressively upon opposite marginal portions of the bottom of a shoe. For effecting relative movement between the work support and the tool support, furthermore, the motor means comprises a plurality of n.c. motors, more particularly stepping motors, including one motor for effecting heightwise movement of the tool support relative to the work support under programmed control.

In said machine, moreover, each tool is mounted on a tool mounting which is pivotally supported by the tool support and at the end of each tool mounting, remote from its pivot, is a link forming part of the height control means, which means also includes a further stepping motor, for controlling the heightwise position of the tool mounting and thus of the tool mounted thereon, relative to the tool support. More particularly, the further stepping motor acts through the link to cause each tool mounting to pivot, thus to vary the heightwise position of the tool mounted thereon.

It will be appreciated that when the machine is in use and the brushes operate upon the marginal portions of the bottoms of a succession of shoes presented thereto, firstly there is some wear on the bristles and secondly it is necessary from time to time to re-grind the tools, again leading to a shortening of the bristles, with the effect that the overall diameter of each brush is decreased. By providing the height control means and by mounting the tools each on a tool mounting pivotally supported by the tool support, it is thus possible to vary the heightwise position of the axis of rotation of each of the brushes so that an operating surface portion of each thereof can be maintained at a datum regardless of the diameter of the brushes. This is especially important in a machine of this type, where the heightwise position of the tool support is accurately controlled. it will of course be appreciated that shoes which are nominally of the same size and style as one another may in fact vary, e.g. because of the thickness of the upper material or indeed of the insole, and consequently it is desirable to provide for a limited amount of "float" of the tool in relation to the tool support, and to this end therefore the height control means comprises, for each tool, an abutment in the form of a pin which co-operates with a slot, constituting a counter-abutment, formed in the link by which the tool mounting is operatively connected to the height control means. The height control means is thus effective to control the heightwise position of the abutment in relation to the tool support whereby to determine the heightwise position of the mounting, and thus of the tool mounted thereon.

Such an arrangement of course, while having proved to be efficient in operation, requires an additional stepping motor or the like, together with the necessary programmed control. Moreover, whereas conveniently the stepping motor can be mounted on the tool support in the case of a machine having a relatively large tool support for supporting two roughing tools side-by-side, such an arrangement may well not be feasible where space becomes a constraint. There is described in FR-A-2-529-763 a machine for operating progressively upon selected surface portions of workpieces comprising a work support for supporting a workpiece with a surface thereof, at least one selected portion of which is to be operated upon, exposed, a tool support for supporting a tool which is to operate upon the selected surface portion(s), and motor means for effecting relative movement between the work support and the tool support in directions extending lengthwise, widthwise and heightwise of such workpiece surface portion whereby to cause such tool to operate progressively therealong.

In this machine, furthermore, a single tool is provided which is supported by a tool carrier itself supported by a tool mounting mounted on the tool support for sliding heightwise movement relative thereto, and in addition the tool carrier is thus supported for rotation about an axis extending heightwise of the work support, drive means, including a d.c. servomotor, being provided for effecting such rotation of the tool carrier whereby in the operation of the machine an operating surface portion of the tool can be maintained in a desired orientation in relation to the selected workpiece surface portion.

In this machine, however, while the motor means is operable to effect relative movement between the work support and tool support in directions extending lengthwise and widthwise of the selected workpiece surface portion under electronic control to follow the profile of such surface portion, e.g. using a line following technique, the control of the heightwise relative movement therebetween is concerned with the achievement of a desired operating parameter (in the particular case of a shoe bottom roughing machine the so- called depth of rough ) , viz. by sensing the power requirement required to operate the tool (in the particular case the tool is a rotary brush and the power requirement by which it is rotated when urged against a selected surface portion of the shoe bottom is sensed) or alternatively by measuring the applied pressure using pressure sensors or the like.

Thus in the case of this machine the height control is related to the operating parameter rather than to following a pre-programmed height profile, as in the case of the machine described in the EP-A referred to above. Indeed the tool support itself is fixed against heightwise movement and the height contour of the selected workpiece surface portion is accommodated merely by the heightwise movement of the tool mounting.

Whereas in this machine, therefore, variations in the diameter of the roughing brush and/or variations in dimensions between successive shoes can readily be accommodated by the height control used for the tool, significant disadvantages may well arise in the actual roughing operation itself by reason of the inertia in the system. This tends to exemplify itself in that as the roughing tool moves "uphill" along a selected workpiece surface portion the brush tends to dig into the material of the workpiece, while as the tool moves "downhill" it tends to bounce along the surface. It was of course essentially to overcome these effects of inertia that in the machine described in the

EP-A referred to above the following of the height profile of the workpiece surface portion was programmed.

It is thus one of the various objects of the present invention to provide an improved machine for operating progressively upon selected surface portions of workpieces wherein the tool is supported for rotation about an axis extending heightwise of the selected workpiece surface portion, without the need for a separate, dedicated, motor for controlling the heightwise position of the tool mounting and thus of the tool mounted thereon.

The invention thus provides, in one of its several aspects, a machine for operating progressively upon selected surface portions of workpieces comprising a work support for supporting a workpiece with a surface thereof, at least one selected portion of which is to be operated upon, exposed, a tool support for supporting a tool which is to operate upon the selected surface portion(s), motor means for effecting relative movement between the work support and the tool support in directions extending lengthwise, widthwise and heightwise of such workpiece surface portion whereby to cause such tool to operate progressively therealong, a tool mounting on which such tool is mounted, said mounting being supported by the tool support for heightwise movement relative thereto, height control means for controlling the heightwise position of the tool mounting, and thus of the tool mounted thereon, in relation to the tool support, the machine being characterised by a tool carrier which carries the tool mounting and which is supported by the tool support for rotation about an axis extending heightwise of the work support, whereby to maintain an operating surface of such tool in a desired orientation in relation to the selected surface portion being operated upon, drive means, including a motor, for effecting such rotation of the tool carrier, and actuating means for operatively connecting the height control means to the drive means, whereby operation of the motor of the drive means is effective to cause heightwise movement of the tool mounting to take place as rotation of the tool carrier about said axis is effected.

It will thus be appreciated that in the operation of the machine in accordance with the invention, the control of the heightwise movement of the tool mounting, and thus of the tool supported thereby, can be achieved without the need for any separate dedicated motor, and moreover it is possible using such an arrangement to include the various parts of the height control means and the drive means in a relatively narrow space, the only addition required being the actuating means. Avoiding the need for a separate motor is of course not only space-saving and indeed cost-saving, but in addition the inertia of the tool support is reduced, thereby enhancing the operation of the machine and its efficiency.

To this end, moreover, conveniently the drive means comprises a spindle rotation of which is effected by the motor, and the height control means comprises a threaded shaft element and a nut element received thereon, one of which elements during the operation of the actuating means is caused to rotate with the spindle while the other is held captive, whereby to effect relative movement between the elements and thus heightwise movement of the tool mounting. More particularly, the threaded shaft element is operatively connected to the tool mounting and rotates in response to rotation of the spindle, and while the actuating means remains not operated the nut element rotates with the threaded shaft element, but upon operation of said means the nut element is held captive against such rotation in the tool support. Moreover, conveniently the spindle is hollow and the threaded shaft element is received therein. By such an arrangement, it will be appreciated, a compact assembly can be achieved for the height control means and the drive means, with the former substantially accommodated within the confines of the latter.

.As in the first machine referred to above, the height control means preferably comprises an abutment and a counter-abutment co-operable therewith and associated with the tool mounting, the height control means being effective to control the position of the abutment in relation to the tool support, whereby to determine the heightwise position of said mounting. Preferably, moreover, the abutment is operatively connected to the one of the threaded shaft and nut elements which is caused to rotate with the spindle while the other is held captive, and thus the position of which is varied when relative movement is effected between the elements. More particularly, therefore, in the machine to be described the abutment is carried by the threaded shaft element and thus operatively connected, in co-operation with the counter-abutment, to the tool mounting. By the provision of an abutment arrangement as aforesaid, of course, a "float" capability is provided in the machine so that in the event of any deviation between the heightwise contour of the workpiece surface portion being operated upon and the path determined by the motor means, the position of the tool can accommodate to any such deviation. Conveniently, the tool mounting is resiliently urged in a direction to bring the counter-abutment into engagement with the abutment, but can move in a contrary direction as the tool mounted thereon moves progressively along the selected surface portion being operated upon. For the sake of compactness, furthermore, where a pneumatic cylinder is provided for thus resiliently urging the tool mounting in said direction, conveniently the threaded shaft may also be hollow and thus provide a passage, or accommodate a pipeline, for the supply of air to said cylinder. By so urging the tool mounting in said direction, not only is the tool held against the selected surface portion of the workpiece being operated upon, but in addition, especially in the case of a pneumatic cylinder, the pressure applied by the tool can be controlled. For further resisting upward movement of the tool against the action of the resilient means, e.g. when a seam or other stepped region is met, moreover, damping means may be provided, said means being effective to damp movement of the tool mounting in said contrary direction. Conveniently the tool mounting is supported for pivotal movement on the tool carrier.

In using the machine in accordance with the invention it may from time to time be desirable to ascertain that an operating surface portion of the tool is correctly positioned in relation to the work support. This would of course be the case for example where the tool is constituted by a rotary roughing tool, e.g. a radial wire brush, the bristles of which will be worn down in the course of the operation of the machine with the result that the overall diameter of the brush is diminished. The machine thus conveniently comprises sensing means for sensing the presence of an operating surface portion of the tool at a datum position, said sensing means generating a signal in response thereto. Generation of such signal in a setting operation of the machine, in which the drive means operates to effect rotation of the tool carrier and the actuating means is operated to cause the height control means to be operatively connected to the drive means, effective to cause such operation of the drive means and the actuating means to be discontinued.

It may also be desirable in the machine to effect a calibration operation, e.g. at the start-up of the machine. To this end, desirably in the calibrating operation the tool mounting is first moved to an upper, predetermined, heightwise position, from which it can then be once more lowered, using the setting means as aforesaid, to position the operating surface portion of a tool mounted thereon appropriately to its size. For the purpose of the calibration operation preferably further sensing means is provided for sensing when the tool mounting is at a predetermined position in relation to the tool carrier and generating a signal in response thereto. Generation of such signal in a calibrating operation of the machine, in which the drive means operates to effect rotation of the tool carrier and the actuating means is operated to cause the height control means to be operatively connected to the drive means to cause the tool mounting to be moved in a direction away from the work support relative to the tool carrier, is effective to cause such movement of the tool mounting to be discontinued.

More particularly, in carrying out a setting operation as aforesaid conveniently relative heightwise movement is first effected between the tool support and the work support to bring the tool towards the sensing means through a predetermined distance, and thereafter the tool mounting is moved towards the sensing means in the manner described above. In the case of a machine in the operation of which the tool may diminish in size during use, e.g. in a roughing operation using a wire brush, where a new brush of relatively large size is mounted on the tool mounting in place of a tool of reduced size, it may be that during the relative heightwise movement effected between the work support and tool support the sensing means senses the tool presence and generates its signal. In such a case, operation of the motor is discontinued, and the tool mounting is moved in an opposite direction under the action of the height control means and the drive means, coupled by the actuating means, until a signal is generated by the further sensing means, indicating the presence of the tool mounting at the predetermined position. In this way, it will be appreciated, calibration is automatically effected for each new tool placed in the machine. It will of course be appreciated that after such calibration has been completed, a setting operation then takes place in the usual manner.

The invention has been found to be particularly appropriate to a machine for performing a progressive roughing operation upon selected surface portions of a shoe, e.g. marginal portions of a shoe bottom, but may equally find application in a variety of other operations. Where the term "heightwise" is used in this specification in relation to the tool, tool mounting, tool carrier or tool support, it is to be understood as indicating movement towards and away from the work support and/or selected surface portions of a workpiece supported by the work support for an operation to be performed thereon.

The above and other of the various objects and several aspects of the invention will become clearer from the following detailed description, to be read with reference to the accompanying drawings, of one machine in accordance with the invention (hereinafter "the illustrative machine") . It will be appreciated that the illustrative machine has been selected for description merely by way of non-limiting example of the invention. In the accompanying drawings:-

Fig. 1 is a side view of the illustrative machine;

Fig. 2 is a plan view of the illustrative apparatus; Fig. 3 is a section view taken on the line III-

III of Fig. 1, showing various motors and other features of motor means of the illustrative machine;

Fig 4. is a fragmentary front view of the illustrative machine, showing details of a roughing tool and its mounting; and

Fig. 5. is a fragmentary side view of a rearward end of the shoe support, showing details of tool datum setting means.

The illustrative machine now to be described is machine for performing a progressive roughing operation along marginal portions of shoe bottoms and comprises a shoe support generally designated 10 (Figs. 1 and 3) and a tool support generally designated 12, the shoe support being mounted for rectilinear movement, in a direction extending lengthwise of the bottom of a shoe supported thereby, in a frame 14 of the machine, and the tool support being carried on said frame, as will be hereinafter described.

The shoe support 10 of the illustrative machine is generally similar to the shoe support described in GB-A-2,077,090 and is thus arranged to support a shoe, bottom up, with marginal portions of the shoe bottom to be operated upon exposed. In the illustrative machine the shoe support 10 is mounted for sliding movement, along a rectilinear path, along two shafts 16 supported by the frame 14. More particularly, a frame 18 of the shoe support is mounted on blocks 20 for such sliding movement. To this end, one of the left-hand blocks 20 (viewing Fig. 3) has depending therefrom a clamp 22 which clampingly engages a belt 24 entrained about two pulleys 26 at opposite ends of the path of travel of the shoe support 10. A forward (i.e. right-hand, viewing Fig. 1) one of the pulleys 26 is driven by a belt 28 (Fig. 3) which is entrained about a drive pulley 30 supported on an output shaft 32 of a stepping motor 34 mounted on the machine frame 14. The stepping motor 34 constitutes first motor means of the illustrative machine, for effecting movement of the shoe support 10 relative to the tool support 12 in a direction extending lengthwise of the bottom of a shoe supported by the shoe support.

The tool support 12 comprises a base 40 (Figs. 1 to 3) which is fixedly mounted on the frame 14. Upstanding from the base 40, moreover, are two support members 42, arranged one at each side of the path of movement of the shoe support. Mounted at 54 (Fig. 2) for pivotal movement on and extending between the support members 42 is a cross-member 44 at each end of which, adjacent the appropriate support member 42, a forwardly extending arm 46 is mounted at 52 for pivotal movement in a direction extending widthwise of the path of movement of the shoe support 10. Interconnecting the forward ends of the two arms 46, furthermore, via ball joints 48 is a tool support member 50, in the form of a casting having a generally planar top surface. The cross-member 44, arms 46 and tool support member 50 constitute a first parallel linkage arrangement of the illustrative machine, facilitating movement of the tool support member 50 in a direction extending widthwise of the path of movement of the shoe support 10, and thus of the bottom of a shoe supported thereby. At the base of each support member 42, and extending inwardly therefrom, is a flange 56 (Fig. 3) on which is supported, by means of a ball joint, a rearward end of a second forwardly extending arm 58 (Fig. 1); each arm 58 extends parallel to its associated arm 46. The forward end of each of the arms 56 is connected, again by ball joint, to a depending lug portion 60 on the tool support member 50. Each support member 42, together with the arms 46, 58 and depending lug portion 60 thus constitutes a set of parallel linkages for supporting the tool support member 50, the two sets (i.e. one on each side of the tool support member 50) constituting a second parallel linkage arrangement of the illustrative machine whereby heightwise movement of the tool support member 50 can be effected relative to the path of movement of the shoe support 10, and thus of the bottom of a shoe supported thereby.

For effecting widthwise movement of the tool support member 50 relative to the shoe support 10 the illustrative machine comprises a stepping motor 66 (Figs. 2 and 3), constituting second motor means of the illustrative machine, said motor being mounted between two brackets 68 secured to the cross-member 44. On the output shaft of the motor 66 is a nut (not shown) captive in a housing 70 secured to a rearward portion of the left-hand (viewing Fig. 3) arm 46 by means of a pin 72. The nut engages with a ball screw 74 whereby rotation of the output shaft is effective to pivot the arms 46, and thus the first parallel linkage arrangement, about the pivots 52 by which the arms 46 are secured to the cross- member 44. On an end of the ball screw, moreover, is mounted a sleeve 76, an end portion of which describes a spiral. This sleeve cooperates with a proximity switch 78 (Fig. 3) and serves as a homing device whereby, in a setting-up operation of the machine, the first parallel linkage arrangement is centralised by operation of the motor 66 to bring the sleeve 76 to a desired position in relation to the proximity switch 78.

Mounted on the base 40 of the tool support 12 is a further stepping motor 84 (Figs. 2 and 3) (constituting third motor means of the illustrative machine) by which the cross-member 44 is caused to pivot about the pivots 54 by which it is mounted on the support arms 42, whereby through the second linkage arrangement to effect heightwise movement of the tool support member 50 in relation to the shoe support 10. To this end, an output shaft of the motor 84 is constituted by a ball screw 86 with which a nut (not shown) engages, the nut being housed captive in housing 88 secured between two brackets 90 extending forwardly of the cross-member 44. Rotation of the motor 84 is thus effective to move the housing 88 heightwise, thus to pivot the cross-member. As in the case of the second motor means, moreover, at the end of the ball screw 86 is arranged a sleeve 92 having a spiral end, said sleeve cooperating with a proximity switch 94 whereby, in a setting-up operation, to return the second parallel linkage arrangement to a "home" position.

In order to counterbalance the weight carried by the arms 46 and support member 50, compensating springs 98 are secured to further brackets 100 carried on the cross-member and also to the base 40 of the tool supporting means 12.

Supported by the tool support member 50 of the illustrative machine is a rotary roughing tool 698 (Figs. 1, 4 and 5) in the form of a radial wire brush, tool driving means being provided for effecting rotation of the brush, as will now be described. The tool driving means of the illustrative machine comprises a motor 110 (Fig. 3) carried by a motor support member 112 which is pivotally mounted on a rod 114 supported at opposite ends on brackets 116 carried on the left-hand (viewing Fig. 3) flange 56 of the support member 42. The motor is thus capable of heightwise pivotal movement about the axis of the shaft 114. A rearwardly extending output shaft of the motor 110 carries a toothed drive pulley 120 (Fig. 1) about which a continuous belt 122 is entrained. It will thus be appreciated that the motor support member 112, and thus the motor 110 itself, is held suspended through the pulley 120 for pivotal movement about the axis of the rod 114; this thus maintains the drive belt 122 in tension. In order to damp any tendency of the motor and its support member to "bounce", moreover, and in order to maintain a constant tension in the belt 122, a piston- and-cylinder arrangement 118 (Fig. 3) is mounted on the cross-member 44 and acts on the member 112 to apply a constant downward pressure thereto.

Mounted, above the drive pulley 120, on a rear portion of the cross-member 44 and centrally thereof are two further pulleys 124 (Figs. 1 to 3) over which the "downstream" and "upstream" portions of the belt 122 are entrained. Each further pulley 124 is mounted on a bracket 126 (Figs. 2 and 3), and each bracket is mounted, independently of the other, for pivotal movement about a pivot 128 carried on a flange formed on the rear of the cross-member 44. Pivotal movement of the brackets 126 is effected in a self-compensating manner according to the direction in which the reaches of the belt 122 extend towards the tool support member 50, as it is moved widthwise of the path of the shoe support 10.

Mounted on the tool support member 50 is a bearing block 672 (Fig. 4) within which is accommodated, for rotation relative thereto, a hollow shaft 674 carrying pulleys 676, 678 at its top and bottom. The hollow shaft 674 itself also provides a bearing for a further shaft 680 which carries at its lower end a tool carrier 682 in the form of a metal block having generally the shape of an inverted L. The tool carrier 682 can pivot about the axis of the shaft 680, as will be described hereinafter. Mounted on a pivot 694 at a lower end of the tool carrier 682 is a tool mounting in the form of a lever 692 which supports at its remote end a tool supporting shaft 696 on which the roughing tool 698 is mounted for rotation. For effecting rotation of the brush 698 a pulley 700 is mounted on the shaft 696 and connected by a timing belt 702 to a further pulley 704 mounted for rotation about the axis of the pivot 694. The pulley 704 is a double pulley and a further timing belt 708 passes thereover and over two angled pulleys 710, 712 and finally about the lower pulley 678 on the shaft 674. The belt 122 driven by the motor 110 is entrained about the upper pulley 676 so that operation of the motor, in the operation of the illustrative machine, is effective, through the various pulleys and belts, to cause the tool 698 to be rotated about the axis of the shaft 686, thus to present a rotating operating surface portion to the bottom of a shoe supported by the shoe support 10.

Referring to Fig. 2, belt-aligning means is also provided adjacent the pulley 676 in order to accommodate to widthwise movement of the tool support member 50, said belt-aligning means comprising two rollers 130 rotatable about a common axis, the rollers having smooth surfaces which run on the back of the timing belt 122. The rollers 130 are mounted on a common bracket 132 which is mounted for pivotal movement about a pin 134 carried by the tool support member 50. The rollers 130 serve to hold the forward end of the belt in alignment with the pulley 676 and are sufficiently wide to ensure that the belt is constantly in engagement therewith, regardless of the widthwise movement of the tool support member; pivotal movement of the rollers about the pivot 134 as widthwise movement of the tool support member 50 takes place is effected by a link 136 pivotally connected at one end to the bracket 132 and at the other to a forward portion of the left-hand (viewing Fig. 3) arm 46. Thus, as the arm 46 pivots, the bracket 132 and thus the rollers 130 are pivoted also. Maintaining the belt in the same plane as the pulley 676 also maintains the belt aligned regardless of the heightwise position of the tool support member.

As already mentioned above, the tool carrier 682 is mounted for pivotal movement about the axis of the shaft 680 (Fig. 4), and indeed the tool is thus mounted for rotational or swivelling movement about said axis. To this end a pulley 684 is mounted at the upper end of the shaft 680 and is connected by a timing belt 686 to a further pulley (not shown) supported on a stub shaft 140 (Fig. 2) on the tool support member 50. Also mounted on the stub shaft is a further pulley 142 connected by a timing belt 144 to a drive pulley 146 on the output shaft of a further stepping motor 148. This latter motor, which constitutes fourth motor means of the illustrative machine, is also carried by the tool support member 50. (The various belts in this drive sequence are all timing belts and the pulleys timing pulleys. ) It will thus be appreciated that by operation of the motor 148 the tool carrier 682, and thus the tool 698 supported thereby, can be rotated about the axis of the shaft 680. In this way, the plane of the roughing brush can be maintained at a desired angle to the marginal portion of the shoe bottom being operated upon at any given time.

From time to time it is desirable to bring the roughing brush 698 to a desired heightwise relationship with the shoe bottom. For example, when the illustrative machine is in use and the brush is operating upon marginal portions of the bottoms of a succession of shoes presented thereto, the bristles tend to wear and indeed the sharpness of the bristles at the operating surface of the tool deteriorates by contact with the shoes so that re-grinding is necessitated from time to time, which again leads to a shortening of the bristles, with the effect that the overall diameter of the brush decreases in use. In order to accommodate the reduction in brush diameter (and this is illustrated in Fig. 4 by showing a brush in its original diameter (in chain-dot line) and in its reduced diameter (in full line)), use is made of the fourth drive means in the manner now to be described. In addition, bearing in mind that shoe bottoms may exhibit irregularities from time to time and indeed a given shoe bottom, though nominally the same as the shoe bottom which has been previously digitised, may in fact be different from it, the rotary brush is mounted on the tool carrier for limited heightwise movement, as will also now be hereinafter described.

For setting limits to the heightwise movement of the tool mounting, and indeed for varying the heightwise position of those limits according to e.g. the diameter of the brush, height control means is provided comprising a further shaft 716 accommodated within the shaft 680, which is hollow for the purpose. The shaft 716, which in the normal operation of the machine thus rotates with the shaft 680, carries at its lower end a block 718 supporting an abutment pin 720. The pin 720 projects from the block 718 and is accommodated in a slot 722 formed at the upper end of a link 724 pivotally connected at its lower end to the tool mounting 692. The slot 722 thus determines the limits of pivotal movement of the lever 692 and thus of the heightwise position of the brush 698 in relation to the pin 720, and thus to the tool carrier 682. It will of course be appreciated that, when the machine is in a rest condition, the link 724 will rest with the upper end of its slot abutting the pin 720, thereby determining the lowermost position of the brush, and in the operation of the machine, when the brush is operating on a shoe bottom, it will be able to "float" relative to the tool carrier 682 within the constraints determined by the slot 722.

The tool mounting 692 is urged downwards by a pneumatic cylinder 730 which is mounted on the tool carrier 682 and a piston rod of which is pivotally connected to a block 732 secured to the tool mounting 692.. The cylinder 730 also is effective to apply a predetermined pressure to the mounting 692, and thus to the tool 698. For limiting "bounce" of the brush, furthermore, a damper arrangement 734 is also supported by the tool carrier 682 and acts against the block 732.

For providing air to the cylinder 730, the shaft 716 is hollow, carrying at its upper end and also at or adjacent its lower end suitable rotary couplings (only the upper one (736) of which is shown in Fig. 4), for connection by pipelines (not shown), respectively to a source of air under pressure and to the cylinder 730. Alternatively, the connection to the cylinder 730 from the air source may be direct.

At its upper end the shaft 716 is threaded with a thread of relatively large pitch. This threaded portion carries a nut 740 which is accommodated within a housing 688 and is provided with a hardened sleeve 742. in the normal operation of the machine the nut rotates with the shaft 716 and thus with the shaft 680, but it is capable of being locked against such rotation, as will now be described. The shank of the nut 740 and the sleeve 742 project into a portion of the housing which is rotatably held by a bracket 690. That portion of the housing is cut away whereby, when the tool carrier is in a "park" position (described hereinafter), to allow access to the sleeve 742 by a plunger 744 actuated by a diaphragm cylinder 746 carried on the bracket 690. The effect of locking the nut 740 while the shaft 680 is being rotated together with the shaft 716 is thus to cause the shaft 716 to move heightwise relative to the nut 740 now locked against rotation, and in this way the heightwise position of the pin 720 is thus varied in relation to the tool carrier 682. This therefore has the effect of varying the heightwise position of the upper and lower limits of movement of the tool mounting 692, and thus of the brush 698, in relation to the tool carrier 682. Because the rotation of the shaft 680, furthermore, is under control of the stepping motor 148, it will be appreciated that the movement of the abutment pin 720 can thus be accurately controlled.

From time to time, e.g. at the start of a working day, the heightwise position of the tool is established in the following manner: firstly the cylinder 746 is operated to lock the nut 740 against rotation and the drive motor for rotating the shaft 680 is then operated to cause the block 718, and thus the abutment pin 720 therewith, to be raised to an uppermost limit position which is determined by a proximity switch 750 carried on the bracket 690. The prox.imity switch senses the presence of a shoulder 752 on a block 754 carried on the upper end of the shaft 716. In this way, the "start" position of the tool is ascertained and can be stored in memory by the control means. When the uppermost position of the abutment 720 is known, it is then necessary to set the operating surface portion of the brush to a datum, according to the diameter of the brush, and to this end tool datum setting means is provided comprising a proximity switch 756 (Fig. 5) arranged at a right-hand (viewing Fig. 3) rearward end of the shoe support 10. For operating the proximity switch 756 a leaf spring 758 is provided which is engageable by the roughing brush to urge it downwards towards the proximity switch, said spring also having a downwardly facing lip 760 by which the proximity switch is actuated. In the operation of the illustrative machine, when a tool datum setting operation has been selected the stepping motor 66 is first operated to move the tool support member 50 widthwise to bring the tool into opposed relationship with the proximity switch 756, and thereafter the cylinder 746 is actuated to lock the nut 740 against rotation and the stepping motor 148 of the fourth motor means is then operated to effective rotation of the shaft 680 as described above, thus to effect downward movement of the tool. Such downward movement is of course discontinued, and the position of the tool thus set at its datum, upon operation of the proximity switch 756. During this operation, the pressure applied by the cylinder 730 is such that the link 724 is held with the upper end of its slot 722 in engagement with the abutment pin 720. It will be appreciated that, by counting the number of "steps" effected by the stepping motor 148 during this tool datum setting operation, the position of the brush is accurately determined and can be stored in the memory.

The shoe support 10 also supports, at a left- hand (viewing Fig. 3) rearward end, a grinding stone 766 into engagement with which the roughing brush 698 may be brought from time to time.

In selecting a grinding operation the motor 66 of the second motor means is effective first to bring the brush into a desired opposed relationship with the grinding stone, whereafter the brush is then again lowered through a predetermined distance under the action of the motor 148 for rotating the shaft 680 and with the nut 740 locked against rotation as aforesaid, generally in the same manner as for a tool datum setting operation. For varying the heightwise position of the grinding stone from time to time as it becomes worn, the stone is mounted on a lever 768 (Fig. 5) supported by a pivot 770 on the shoe support 18. The end of the lever remote from the pivot is pivotally connected to one arm of a ball crank lever 772 itself also pivotally mounted on the shoe support. Operatively connected to the other arm is a manually operable adjustment screw 774, rotation of which thus effects, through the aforementioned linkage, heightwise movement of the stone 766

In the operation of the illustrative machine, a shoe is first mounted in the shoe support 10, bottom uppermost, with the heel end of the shoe rearwardly (i.e. facing away from the operator) , the shoe then being clamped both lengthwise and widthwise, and the heel end thereof being centralised, as described in detail in GB-A-2,077,090. At the same time the length of the shoe is "measured" and whether it is a left or a right is detected, again as described in the aforementioned GB specification. The illustrative machine is provided with a control panel generally designated 160 (Fig. 2) by which the operator can select a programmed instruction according to the style of shoe to be operated upon. With the style selected, the operator can initiate a cycle of operation of the machine and the roughing tool 698 is then caused to operate progressively around the marginal portion of the shoe bottom in order to rough it, the direction of rotation of the brush being such that it always "wipes" inwardly over the marginal portion of the shoe bottom being operated upon, and to this end the brush is caused to swivel about the axis 680 to maintain it in a desired angular relationship with the shoe bottom. The particular angle at which the brush is oriented in any particular position is again controlled by the programmed instruction, as is also the particular pressure applied at any particular position and indeed the speed of rotation of the brush, all of which are variable during the operating cycle.

For creating a programmed instruction, the machine has a path-determining mode in which the tool is moved under operator control to a succession of positions along the marginal portion of the shoe bottom and each position is then "taught" in terms of three coordinate axes (as described in detail in US-A-4,541,054) , brush rotational speed and brush pressure (as described in detail in EP-A-0 511 814) and swivel angle (as will now be described) .

For effecting the path-determining operation, a succession of displays are exhibited on a display panel 162 of the control box 160, asking the operator in turn to indicate a value for each of the various settings; in addition cursor keys (which could otherwise be in the form of a joystick) are provided on the control box for effecting widthwise and heightwise movement of the tool under operator control, again as described in detail in US-A-4,541,054; these cursor and other keys are indicated generally at 164 in Fig. 2. In the case of setting the swivel angle, the operator utilises two directional keys 164 according to the direction of rotation selected for re-orienting the brush about the axis of the shaft 680. When the various settings have been made, the operator merely operates a "teach" key 164, whereupon the shoe support drive motor 34 is then actuated to move the shoe to a next position, as described in the aforementioned US-A-4,541,054. When the tool has thus been caused to progress under operator control along the whole of the periphery of the shoe bottom, the programmed instruction is then stored as a pattern data file in volatile memory and may if desired then be transferred to non-volatile memory. When the particular style of shoe to which the file relates is thereafter selected for treatment, the file is also selected and the tool automatically follows the "taught" path, which is determined by the various "taught" points with an interpolated line therebetween; the angle of swivel of the tool is also determined by an interpolation between the "taught" angles of orientation. As in the case of the machine described in e.g. EP-A-0 043 645, a grading programme may also be provided by which the data in the file is modified according to the length of the shoe as measured by the shoe support 10, and in addition the "Y-axis" values may be reversed so that the same data can be used for left and right shoes.

For removing dust and other debris created during the roughing operation from the operating locality of the illustrative machine dust extraction means is provided, including a collector head 170 which is constituted by a cylindrical drum mounted on the underside of the tool support member 50 concentrically with the shaft 680.