GB2294428A - Marking apparatus - Google Patents

Abstract

A marking apparatus such as a blocking, labelling or embossing machine comprises a moveable workpiece fixture (18) for presenting workpieces successively to a marking member(40) arranged to cooperate with the workpiece presented thereto, all powered functions of the machine being electrically driven. The apparatus may be a blocking machine where the marking head is reciprocated towards and away from a workpiece or the periphery of a workpiece is brought into contact with a marking wheel via a marking tape. The apparatus may also include an indexing device in which a rotary driving member intermittently indexes a rotary driven member and locates the driven member at each indexing station whilst continuing to rotate and drive other machine functions. <IMAGE>

Description

MARKING MACHINE AND AN INDEXING DEVICE SUITABLE FOR USE THEREWITH This invention relates to a marking machine such as a blocking, labelling or embossing machine, and further relates to an indexing device.

The process of hot blocking is the application of printing, logos and other designs to articles e.g. plastics, cosmetics and toiletries containers using a heated die which transfers the legend by impressing heat transferable tape, metal foil tape or blocking medium, labels or other medium to the article. Hot blocking can be of at least two types. One form of hot blocking is known as "top blocking", where a marking head is reciprocated towards and away from a workpiece. Another form of hot blocking is known as "peripheral blocking", where the periphery of a workpiece is brought into contact with a marking wheel via a marking tape; marking is effected by rolling the workpiece with respect to the marking wheel.

Hitherto the blocking of such articles on a production basis has been undertaken by the use of machines employing compressed air.

Since hot blocking can be performed separately from other production operations it is susceptible to being undertaken economically by small (sometimes very small) businesses.

Such businesses however seldom have a shop air line or other integrated air supply and so can only use existing blocking equipment by acquiring a portable compressor, which is both inconvenient and noisy.

The present invention seeks to provide a hot blocking or similar machine which does not require a compressed air supply.

Thus in one aspect the invention provides a marking apparatus comprising a moveable workpiece fixture for presenting workpieces successively to a marking member (for example, a blocking, labelling or embossing head) arranged to cooperate with the workpiece presented thereto, all powered functions of the machine being electrically driven.

The fixture may be a rotary fixture with a plurality of angularly spaced apart stations each for receiving a workpiece, the machine comprising an indexing device to index the fixture successively to present said stations to the marking member.

Preferably, means is provided for reciprocating the marking member towards and away from the workpiece.

Preferably, the apparatus includes an electric motor for driving the reciprocating means, and control means for controlling the electric motor and having switch means for switching the motor on and off, the control means being arranged to control the motor such that, when it is switched off, the marking member is positioned away from the workpiece.

Preferably, the fixture and the reciprocating means are driven by a single electric motor.

Preferably, the apparatus includes an electric motor for driving the marking member, the motor being arranged to rotate continuously during operation of the apparatus.

This invention also seeks to provide an indexing device which is particularly suitable for use with apparatus as set forth above, and which may permit the aforesaid continuous rotation of the motor.

Thus in another aspect the invention provides an indexing device for a rotary workpiece fixture or the like comprising a rotatable driven member, a driving member adapted to rotate and periodically to engage the driven member and rotate it through a predetermined angle from one indexing station to the next, the driving member also being arranged to locate the driven member at each said indexing station whilst continuing to rotate.

One of the driving member and the driven member may comprise a plurality of radially extending slots or projections equally angularly spaced about its axis of rotation, the other member comprising either a projection or a slot spaced from the axis of rotation of the said member and adapted periodically to engage a said slot or projection respectively whereby the driving member rotates the driven member through the predetermined angle.

Preferably the driven member is provided with a plurality of said slots and comprises an arcuate recess in its periphery between each slot, the driving member being spaced from the driven member and comprising a portion of arcuate form of radius such as to be closely received within a said recess in the driven member whilst rotating whereby to locate the driven member at an indexing station, the arcuate portion, being disengaged from the recess by further rotation of the driving member to permit rotation of the driven member to the next indexing station.

The driven and driving members may be rotatable about spaced parallel axes.

The projection may be disposed on the driving member at a radius greater than that of the arcuate portion thereof, the arcuate portion being defined by a circular structure having a recess in the periphery thereof, shaped to permit portions of the driven member defining the slots to pass the driving member, the projection being disposed on the driving member or an axis of symmetry of the recess therein.

The invention extends to apparatus including an indexing device as aforesaid and a rotary workpiece fixture, and further including means for ejecting a workpiece from the fixture.

In a further aspect, the invention provides apparatus including an indexing device as set forth above, and comprising a rotary fixture having a plurality of angularly spaced apart stations each adapted to receive a workpiece, processing means for performing an operation on a workpiece, the indexing device being arranged periodically to rotate the fixture to present the workpieces at said stations successively to the processing means, the driving member of the indexing device driving the processing means whilst locating the driven member.

The processing means may be driven by the driving member via a preferably toothed belt which extends between respective pulleys on the driving member and the processing means the axes of the pulleys being non-parallel, and a pair of opposed tapered rollers may be provided between the two pulleys to guide the belt.

The apparatus may be a marking (for example, blocking, labelling or embossing) machine, the processing means comprising a marking head arranged to reciprocate forwards and away from the workpiece presented thereto.

There may be means for reversing the direction of rotation of the rotary workpiece fixture to suit a left-handed or right-handed operator, for example, means for reversing an electric motor which may power the driving means.

The workpiece fixture may be mounted on a platen, the inclination of which is adjustable to suit the operator.

The reciprocating movement of the marking member may be derived via a crank from the driving member or other rotating parts used also to drive the indexing device.

There may be a device for feeding a marking tape (for example, of blocking medium or labels) to the marking member, the feed device for the tape being driven from the reciprocating motion supplied to the marking member.

According to a further aspect of the present invention, there is provided apparatus for marking workpieces, comprising a marking member and an indexing device for presenting the workpieces in turn to the marking member for being marked, the indexing device including means for mounting each workpiece so that it can rotate relative to the marking member during marking, whereby the periphery of the workpiece can be marked.

This arrangement, by use of the indexing device, can permit the "peripheral blocker" of this aspect of the invention to process workpieces in quick succession.

Preferably, the marking member is a (blocking) wheel which is arranged to rotate continuously during operation of the apparatus.

This has been found pursuant to the present invention to be an effective way of operating the marking member with an indexing device. Since the wheel is continuously rotating, the timing of the indexing device with respect to the wheel does not need to be controlled; the workpiece can be presented to the wheel at any time.

According to a further aspect of the present invention, there is provided a device for marking a workpiece, comprising means for mounting a length of marking tape, a marking member for marking the workpiece with the marking tape, and means for mounting the workpiece so that it can be in rolling cooperation with the marking member via the marking tape, the tape being arranged to be advanced only when the workpiece is in said rolling cooperation.

By advancing the tape only when the workpiece is in rolling cooperation with the marking member via the tape, the usage of tape can be kept to an absolute minimum. All tape which is advanced to the marking member can be used in the blocking process; none need be wasted.

Preferably, the marking tape mounting means includes means for pulling the tape in a tape feeding direction and means for applying resistance to the tape to resist the pulling means, the resistance being arranged to overcome the pulling force except when the workpiece is in said rolling cooperation. This has been found to be a simple and effective way of putting the invention into practice which has the particular advantage that the resistance and the pulling force can be arranged to keep the tape taut across the marking member.

Preferably, the means for applying resistance comprises a spiral spring adapted to contact the tape. A spiral spring, especially one with multiple turns, can exert a substantially constant resistance on the tape notwithstanding the distance of the tape from the centre of the spring. Also, the resistance is unaffected by the orientation of the spring (so that the whole peripheral blocking device can be used at different angular orientations).

If the pulling means includes a rotary actuator arranged to drive a take-up spool for the tape, the drive may be via a frictional coupling, preferably an adjustable such coupling, so that the pulling force can be accurately pre-set regardless of whether the tape is being advanced or not.

For the sake of economy, preferably the length of marking tape used to mark the workpiece is adjustable.

In the preferred embodiment, the marking member is a wheel which is arranged to rotate during operation of the device, and the speed of rotation is adjustable. By adjusting the speed of rotation of the wheel, the length of tape used for marking can be adjusted. Hence, for example, the periphery of the workpiece need only be marked once.

This can save on the amount of tape used.

In one preferred embodiment, the workpiece mounting means and the marking member are arranged to be moveable bodily relative to each other during operation of the device, so that a workpiece not possessing circular symmetry can be marked. This feature may also be provided independently.

Preferably, the workpiece mounting means permits rotation of the workpiece about an axis and the marking member is rotatable about a further axis, and, during operation of the device, either the workpiece mounting means permits movement of the workpiece along its axis or the marking member is movable along its axis, or both. Hence the workpiece can be marked with lines which, when viewed in projection, are curved. For example, a wavy line can be marked onto the workpiece. In the preferred embodiment, the workpiece mounting means is so arranged that rotation of the workpiece causes the workpiece to reciprocate along its axis in a predetermined manner.

Preferably, the workpiece mounting means and the marking member are so arranged that the angle between the workpiece and the marking member is adjustable. Hence frusto-conical workpieces and the like can be marked.

As mentioned earlier, the marking machine may also include a device for ejecting the workpiece. This device may be driven by the single electric motor. It may be synchronised to eject the workpiece whilst the driven member is located at an indexing station.

The present invention will now be described, purely by way of example, with reference to the accompanying drawings in which: Figure 1 is a side elevation of a first embodiment of hot blocking machine according to the invention, including a top blocking device; Figure 2 is a view on arrow 2 of Figure 1; Figures 3 and 4 show parts of the machine of Figure 1; Figure 5 is a partial view equivalent to Figure 1 of a modified machine according to the invention; Figure 6 is a top plan view of a second embodiment of hot blocking machine according to the invention, including a peripheral blocking device; Figure 7 is a cross-sectional view of the peripheral blocking device of Figure 6, the cross-section being taken alung the line XX' shown in Figure 6; Figure 8 is a similar cross-sectional view, the cross-section being taken along the line YY' shown in Figure 6;; Figure 9 is a side elevational view, to a larger scale, of an ejection device according to the present invention; Figure 10 is a top plan view of the ejection device; Figure 11 is a partly sectioned side elevational view, to a larger scale, of a workpiece fixture arrangement according to the present invention; and Figure 12 is a front elevational view corresponding to the side elevational view of Figure 11.

Referring to Figures 1 and 2, the marking machine of the present invention comprises a vertical plate 10 supported from the floor by a frame (not shown) provided with castors and/or levelling feet. Hinged to the top edge of the plate 10 is a platen 12, the hinge axis being shown at 14.

A toothed quadrant 16 is centred on the axis 14 and can be rotated by means of a key engageable with a reduction pinion (not shown) meshing with the quadrant. Rotation of the quadrant pivots the platen 12 enabling it to be set at a convenient angle for the machine operator. Holes 17 are provided to receive a locking peg to secure the table in its inclined position.

The indexing device of the present invention is now described. Mounted in the platen 12 is a rotary indexable table 18 having a number (eight in this case) of equally angularly spaced fixtures 20 each for receiving a workpiece to be hot-blocked. The axis of rotation of the table is shown at 22, and beneath the platen is an indexing device comprising driving and driven members 24, 26. The driving member 24 is powered via a toothed belt (not shown) and pulley 27 by an electric motor (not shown) mounted on the plate 10, suitably geared-down so that the table 18 presents the workpiece to the blocking head (described later) at an appropriate rate, say one per second.

Referring to Figures 3 and 4, the driven member 26 of the indexing device comprises eight equally spaced radial slots 28, equal in number to the workpiece fixtures 20. Between the slots are arcuate recesses 30. The driving member 24 comprises a circular portion 32 of radius slightly less than that of the recesses 30, and a driving peg or projection 34 positioned at a larger radius from the axis of the driving member 24 than the radius of the circular portion 32. The driving and driven members 24, 26 are arranged to rotate about parallel axes 22, 36 (Figure 1) spaced such that the circular portion 32 is a close running fit in each recess 30 (Figure 4).

Part of the circular portion 32 is cut away to form a further circular recess as shown at 38. The recess 38 is centred on the axis of the driving peg 34 and thus is symmetrically disposed about the peg 34.

In operation, rotation of the driving member 24 causes the peg 34 to enter a slot 28 (in which it is a sliding fit) as shown in Figure 4 and to rotate the driven member until it disengages from the slot. The circular portion 32 meanwhile has engaged the recess 30 and, upon the peg 34 leaving the slot 28, it fixes the driven member 26 against further rotation. The driven member 24 continues to rotate and in due course the peg 34 enters the next slot 28, the portion 32 disengages from the recess 30, and the sequence is repeated. It will be appreciated that the recess 38 is shaped such that it provides clearance for the cusps 39 of the driven member 26 defining the slots 28 to pass the driving member 24.

The top blocking device of the present invention is now described. A hot tape blocking head 40 is mounted on a pair of rods 42 (Figure 2) slidably mounted in guides 44 for vertical reciprocation so as to apply for example heat transferable tape to a workpiece by means of an electrically-heated die 46. The rods 42 are driven by links 47 and cranks 48 mounted on a crankshaft 50 carried in the guide structure 44 from the platen 12. The crankshaft is provided with a profiled (toothed) pulley 51 driven via a twisted toothed belt (not shown) from a similar pulley 52 attached to the indexing driving member 24. The toothed belt provides a positive drive to the crankshaft 50, ensuring that the motion of the blocking head is correctly phased with the indexing of the table 18.

As will be apparent from Figures 1 and 2, the axes of the pulleys 51 and 52 are at right angles to each other, so that the toothed belt is twisted through 90. Twisting of the belt is assisted by a pair of 30 frusto-conical rollers (not shown) mounted near pulley 51 but having their axes parallel to the axis of pulley 52. The two rollers face in opposite directions, one roller bearing down on the upper face of the upper portion of the belt as it enters (or exits) pulley 51, the other bearing up on the lower face of the lower portion of the belt as it exits (or enters) pulley 51, both rollers acting to pinch their respective portion of the belt towards the other.

Hence the rollers serve to twist both the upper and lower portions of the belt in the same direction, and thus to guide the belt as it twists from the orientation of pulley 52 to that of pulley 51. The angle of the rollers is not critical; it is dependent partially on the location of the rollers relative to the pulleys 51 and 52. It has been found that the use of two conical rollers having the same cone angle permits reversal of the direction of travel of the belt without any deleterious effects. In one direction of travel, the belt rides up one pulley and down the other, and vice versa for the other direction of travel.

It will be appreciated that the continued rotation of the driving member 24 whilst locating the driven member 26 (and hence the table 18) enables a single motor easily to drive both the indexing table 18 and the blocking head 40, in contrast to the complicated compressed-air arrangements used hitherto.

The position of the die head at the lowest point of its stroke is adjustable by means of a pair of sprockets 56 in a cross-head 58 in which the rods 42 are mounted. The lower ends of the rods are threaded and pass through the sprockets, which are rotatable together by a pinion 60 having a square boss 62 engageable by a key, suitably the same one as used for adjusting the quadrant 16. Rotation of the sprockets 56 raises or lowers the rods 42 and hence the die head relative to the crankshaft 50.

The heated die is fed with marking tape 63, in the form of heat transferable tape, metal foil tape or labels, from a roll 64, via tensioning rollers 65. The feed is intermittent, an appropriate amount of tape being advanced for each stroke of the blocking head.

The tape advance mechanism is driven from the motion of the crosshead 58, via levers 66, 68 (Figure 1), the latter being pivoted on the guide 44. The lever 68 raises a toothed rack 70 via a follower 72 on the end thereof. The rack is returned by a spring 74 to an adjustable stop, adjustment of the position of which allows the feed of the tape to be adjusted appropriately to the amount needed for each blocking operation. The tape is advanced by the return motion of the rack, which drives a pulley 76 connected by a belt 78 to a take-up spool 80 for the spent tape. The pulley 76 drives the spool 80 on the downward stroke of the rack 70, but is provided with a one-way clutch enabling it to idle when the rack is being raised by lever 68.The tape feed is resisted to a limited extent by a multi-turn clockwork-type flat spring 81 which has adjacent its distal end a portion 81a which is arcuately shaped, to bear on the exposed surface of the tape on roll 64. It hence acts as a feed tensioner for the tape. By virtue of the multiple spiral turns on the spring 81, the feed tension remains substantially constant irrespective of the amount of tape on the roll 64. In the present embodiment, the spring is 1/3mm thick. It is polished where it contacts the tape, to prevent abrasion of the tape.

The machine is provided with appropriate safety devices for the protection of the operator, the primary function of whom is to load work pieces onto the fixtures 20, and unload them after they have been blocked (unless an ejection device, described later, is employed). The safety devices comprise pivoted guards 82 which if deflected, eg by the operator or by a misplaced workpiece, open microswitches 84 and stop the motor. The microswitches 84 form part of a control means (not shown) for controlling the operation of the machine.

The control means also includes a further microswitch operated by a cam (not shown) on the crankshaft 50 which maintains a parallel supply to the motor when a microswitch 84 is open, until the blocking head is at the top of its stroke. The motor then stops; since the blocking head is stopped at the top of its stroke, a misplaced workpiece can be removed easily and there is less likelihood in the event of an accident that an operator's hand will remain trapped in the machine. The loading and unloading operation of course is amenable to execution by a conventional pick-and-place robot, but the safety devices still will be advantageous to protect the machine in the event of mishap.

The control means also controls other functions of the machine, such as stop and start, and the temperature of the electrically heated die 46.

The rotation of the table 18 can be suited to either a right-handed or left-handed operator by the provision of a reversing switch for the motor.

In the embodiment of Figure 5 the pulley 27 is omitted and the motor (here shown at 90) powers the driving member 24 via a worm-reduction gearbox 92, the output shaft 94 of which is received within the lower end 96 of the driving member 24 and secured therein by a cotter pin 98. The motor 90 is carried on a sub-frame 100 which is supported from the plate 10 by resilient anti-vibration mountings 102.

The second embodiment of hot-blocking machine according to the present invention is now described with reference to Figures 6 to 8 of the drawings.

The second embodiment of hot-blocking machine comprises in broad terms a peripheral blocking device and the indexing device described previously with reference to Figures 1 to 5. The peripheral blocking device is designed to be easily interchangeable with the top blocking device of the first embodiment. As shown in Figures 6 to 8, the peripheral blocking device is bolted onto the plates 12 of the indexing device in the same location as the top blocking device is shown mounted in, for example, Figure 1.

The peripheral blocking device comprises in general terms a marking member in the form of a blocking wheel 200, a drive arrangement 202 for the blocking wheel, a heating arrangement 204 for the blocking wheel, an adjustment arrangement 206 for adjusting the pressure of the blocking wheel on the workpiece, and an arrangement 208 for mounting a length of marking tape 210, such as heat transferable tape, metal foil tape or labels, for feeding to tne blocking wheel.

In more detail, the blocking wheel 200 comprises a flanged metal wheel 220, a ring 222 of silicone rubber mounted on the recessed portion of the wheel 220, and a metal disc 224 bolted to the wheel and clamping the ring 222 in place. It is the ring 222 which contacts the workpiece.

The drive arrangement 202 for the blocking wheel comprises an electric motor 230 with an integral reduction gearing arrangement 232 driving a first toothed pulley 234 which in turn drives a second toothed pulley 236 via a toothed belt 238. The second toothed pulley 236 is mounted on a drive axle 240 arranged to drive the blocking wheel 200. The axle rotates in a pair 242 of bearings attached to the platen 12. The speed and gearing of the motor 230 is such that the drive wheel 200 can be rotated at a rate suitable for peripheral blocking of a workpiece, say 1/2 revolution per second.

The heating arrangement 204 comprises two elongate heating elements 250, 252 mounted as shown in Figures 6 and 7 adjacent the silicone rubber ring 222 for heat transfer to the ring. Sheets 253 of heat-proof material, such as asbestos (or asbestos substitute) enclose the heating elements 250, 252 and the blocking wheel 200 to help prevent danger to the user. They also serve to retain heat in the heating arrangement 204. A thermocouple 254 allows the temperature of the heating arrangement to be thermostatically controlled by the control means (not shown). Finally, as part of the heating arrangement, the blocking wheel 200 includes holes 256 for dissipating heat.

The function of the heating arrangement is to heat up the rubber ring 222 to a temperature suitable for hot blocking.

To achieve this, the heating elements may need to operate at temperatures in excess of 250"C. The silicone rubber ring will be at a somewhat lower temperature. Indeed, to avoid hotspots and premature failure of the ring, the blocking wheel would usually need to be rotated continuously whilst the heating arrangement is in operation.

The adjustment arrangement 206 for adjusting the pressure of the blocking wheel 200 on the workpiece comprises a mounting plate 260, on which the bulk of the peripheral blocking device is mounted, pivotally attached to the platen 12 by a pivot spindle 262. The precise angular orientation of the mounting plate 260, and hence the pressure the blocking wheel 200 exerts on the workpiece, are adjusted by the screw adjuster 264. The pressure is normally adjusted by trial and error until optimal performance of the blocking device is achieved. Once the mounting plate 260 is adjusted, it is clamped in position on the platen by two clamp bolts 266 and 268 sliding in respective slots 270 and 272.

It is to be noted that the spacing of the blocking wheel 200 from the mounting plate 260 is dictated by the length of spacer members 274. Spacer members of different lengths can be used if necessary.

Finally, the arrangement 208 for mounting and feeding the length of tape 210 includes a feed spool 280, a take-up spool 282, a feed tensioning mechanism 284 for tensioning the feed of the tape 210, two guides 286 and 288 for the tape, and a drive mechanism 290 for the take-up spool 282.

It is to be noted that the guides 286 and 288 are mounted on the same pillars which bear the pivoted guards 82 referred to previously. The feed spool 280 incorporates an inner disc 291, and an outer disc 292 which is removable to permit loading of fresh tape. The discs 291 and 292 are of sufficient diameter to provide guidance for the tape 210.

The feed spool is free to rotate, but its rotation is resisted to a limited extent by the feed tensioning mechanism 284. This comprises a multi-turn clockwork-type flat spring 294 which has adjacent its distal end a portion 296 which is arcuately shaped, to bear on the exposed surface of the tape on the feed spool 200. The details of the spring are the same as those of the spring 81 described in relation to the first embodiment of hot-blocking machine. The guides 286 and 288 are arranged to guide the tape over the silicone rubber ring 222 of the blocking wheel 200.

The drive mechanism 290 for the take-up spool 282 includes a first toothed pulley 298 mounted on the drive axle 240, a second smaller diameter toothed pulley 300, and a toothed belt 302 to transfer drive from the first to the second pulley. A belt tensioner 304 is provided. This includes two needle rollers 305 acting on the upper and lower portions of the belt 302. The belt tensioner is centrally pivotable for adjusting the tension of the belt. It also serves to keep the belt clear of the nearer of the spacer members 274. The second pulley 300 drives the take-up spool 282 via a frictional clutch coupling consisting of a disc 306 of silicone rubber which is mounted between the pulley 300 and a bearing surface 308 on the take-up spool 282, and is free to rotate with respect to both surfaces.The driving torque exerted by the drive mechanism 290 can be adjusted by means of coil spring 310 whose compression can in turn be adjusted by sliding adjustable collar 312 along take-up spool spindle 314.

The driving torque is set so that, when the workpiece is not in rolling cooperation with the blocking head, the torque does not quite overcome the resistance afforded by the feed tensioning mechanism 284. Hence no tape is fed unless the workpiece is actually being marked by the blocking head.

It will be appreciated that the gearing ratio between the first and second pulleys 298 and 300 needs to be such that when the clutch is fully engaged the tape 210 could be recovered faster than the rate which is actually required to mark the workpiece.

The take-up spool 282 itself includes inner and outer guide discs 316 and 318 which are mounted either side of a plastic ring 320. This ring 320 is a tight push-fit on a roller 322 mounted on bearings on the take-up spool spindle 314; the ring is used for mounting the tape 210. The inner guide disc is clamped in position on the roller 322 whilst the outer one is a tight sliding fit for easy removal.

In operation, the blocking wheel 200 of the peripheral blocking device is maintained continuously rotating. When the next workpiece is presented to the blocking wheel by the indexing device, as soon as the two come into contact via the tape 210, the workpiece rotates and its periphery is marked by the metal foil on the tape, which is hot-blocked onto the workpiece. Contact between the wheel and the workpiece via the tape overcomes the feed resistance afforded by the feed tensioning mechanism 284 and causes the drive mechanism 290 to feed the tape onto the take-up spool 282. Marking of the workpiece and feeding of the tape ceases when the workpiece is moved out of contact with the blocking wheel by the indexing device.

The speed of the motor 230 can be manually varied at the control means (not shown), so that, for example, the periphery of the workpiece is in contact with the blocking wheel 200 for just one (or slightly more than one) revolution of the workpiece. This can ensure minimal use of the tape 210.

In a modified embodiment of the peripheral blocking device, the arrangement 206 for adjusting the pressure of the blocking wheel 200 on the workpiece is rendered freely pivotable about the pivot spindle 262 by the omission of the screw adjuster 264 and clamp bolts 266 and 268. A biassing means (such as a weight or some form of tensioning device) bears on the mounting plate 260 so that the blocking wheel exerts the same pressure on the workpiece irrespective of the precise angular orientation of the mounting plate. Hence the modified device can be employed to mark non-circular workpieces, the pivoting of the mounting plate being able to accommodate the non-circularity of the workpiece.

It will be understood that the peripheral blocking device described above operates without compressed air. The only power required is electricity to power the electric motor 230 and heating elements 250 and 252. As is also the case with the indexing device, this power can be provided from a standard household electricity socket (such as a 13 Amp socket in the United Kingdom).

It will also be appreciated that the peripheral blocking device is detachable as a single unit from the hot-blocking machine as a whole. The power supply for the peripheral blocking device is derived by plugging this device into a socket associated with the control unit of the machine.

Optional to the hot-blocking machine is a device for ejecting a workpiece from its fixture 20 once the hot-blocking has been accomplished. This device can be used with both the top blocking and peripheral blocking devices described above.

This ejection device is now described with reference to Figures 9 and 10, in which it is denoted 400. In these figures, like paris to those described with reference to the preceding figures are denoted by like reference numerals.

The ejection device 400 comprises generally a crank assembly 410 driven indirectly by the single electric motor powering the machine, an ejector assembly 430 driven by the crank assembly and arranged to operate in synchronism with the indexing device to eject each workpiece once it has been marked by the marking member, and a connector assembly 450 for connecting the crank and ejector assemblies.

In more detail, the crank assembly 410 comprises an extension arm 412 extending in prolongation of the lever 68 so that it pivots therewith, a crank foot 414 bolted to the extension arm, and a pair of flat steel cranks 416, 418 pivotally attached to the crank foot. The extension arm is cranked to bring the crank foot 414 in line with the ejector assembly 430. The pivotal attachment between the cranks 416 and 418 and the crank foot 414 is effected by means of a respective bronze bearing bush 420, 422 for each crank 416, 418. This is of slightly greater thickness than the cranks, is located in a hole in its respective crank, and is secured in place by respective clamp bolts 424 and 426. Retaining washers 427 and 428 restrain the cranks from slipping off the clamp bolts.The crank assembly 410 functions to convert the pivoting motion of the lever 68 into a reciprocating motion for the ejector assembly 430.

The ejector assembly 430 includes a 4mm diameter ejector pin 432 which is adapted to be reciprocated through a bore 434 in the indexable table 18 to eject each workpiece in succession. The bore may serve the additional function of allowing direct access to the workpiece fixtures 20 whilst the table 18 is in the locked condition. The ejector pin is restrained to slide within an ejector bearing 436 extending through the platen 12 and held in place on the platen by a circlip 438 against a flanged portion 440 of the bearing.

The flanged portion 440 has a machined cut-out 442 to clear the inside of the crank foot 414 at the extreme forward part of its stroke. The bearing 436 is sufficiently long to support the ejector pin 432 and connector assembly 450 even at the back of its long stroke.

The connector assembly 450 includes a carrier block 452, the same width as the crank foot 414, to which are pivotally attached the cranks 416 and 418 via further bearing bushes, further clamp bolts, and further retaining washers, in like manner to the components 420 to 428 described above. The ejector assembly 430 is attached to the connector assembly by means of an 8mm diameter adjusting bolt 454 which is welded to the ejector pin 432 and is threadedly engaged with the carrier block 452 to enable the extent of protrusion of the ejector pin to be varied. The adjusting bolt 454 is locked in place by pinch bolt 456.

In Figure 9, the crank assembly is shown roughly at its mid-stroke position. In this position, the cranks 416 and 418 are roughly in line with the ejector pin 432, passing either side of this pin towards each extreme of travel, so that maximum linear movement of the ejector pin is obtained. The crank foot 414 is cranked in order that its pivotal attachment to the cranks 416 and 418 may come as close to the platen 12 as possible in the extreme forward position of the stroke. The ejector pin 432 is of a length such that with the adjusting blot 466 fully forwards and the ejector pin length hence effectively at a maximum, the tip of the ejector pin is withdrawn from the back of the indexable table 18 before the table starts to move. In the present embodiment, the useable stroke of the ejector pin is variable between 15 and 35mm.

Ejection can be performed when the indexable table 18 is being indexed either clockwise or anti-clockwise, dependent upon where the ejection device is mounted. If it is desired to eject workpieces with the indexing being carried out in either direction, two ejector devices would need to be provided, with the levers 66 and 68 then being duplicated, and with the second lever 68 being cut off just above its pivot point with the lever 66 to clear the guard.

In operation, as the crosshead 58 of the hot-blocking machine advances downwardly, the ejector pin 432 begins to advance, passing up into the bore 434 of the table 18, and eventually ejecting the workpiece from the workpiece fixture 20. Subsequent to this, the pin recedes again.

Since the ejection device is a mechanical device which is directly linked to the crosshead of the machine, as such it moves in harmony with the rest of the machine; in particular, it is synchronised with the indexing device so that the ejector pin 432 only projects onto the table 18 when the table is stationary. Typically, the synchronisation might be such that the workpiece might be ejected once it has reached the first index position past the position at which it has been hot-blocked.

In a variant of the ejection device, the ejector pin could be spring loaded to guard against accidental damage.

In another variant of the device, the actual ejection could be effected by a slave ejector plunger fitted in the indexable table 18 and operated by the ejector pin.

A workpiece fixture arrangement according to the present invention is now described with reference to Figures 11 and 12. This arrangement can replace the standard workpiece fixture 20 in circumstances, for example, where the workpiece is of an awkward shape or where curved rather than straight lines are required to be blocked onto the workpiece. Normally, the same number of such fixture arrangements would be provided as fixtures are provided for the previously described embodiment.

The fixture arrangement has three main functions. The first is fulfilled by a carriage assembly 500 for mounting the workpiece such that it can move substantially in the plane of the blocking wheel 200. Hence the surface of a workpiece not possessing circular symmetry can be in continual contact with the blocking wheel despite its contour by virtue of compensatory movement of the carriage assembly. Thus the workpiece can be marked successfully.

The second main function is fulfilled by a reciprocating mount 502 arranged such that rotation of the workpiece causes the mount to reciprocate along its axis in a predetermined manner, so that wavy or other curved lines can be marked onto the workpiece.

The third main function is fulfilled by a tipping arrangement 504 allowing the angle between the workpiece and the marking member to be adjustable. This can permit frusto-conical workpieces and the like to be marked, by arranging for the surface to be marked to be perpendicu]ar to the plane of the blocking wheel 200.

The carriage assembly 500 comprises generally two fixed bearing shafts 510 and 512, a block-shaped carriage member 514, which member is slidable along the bearing shafts, and a pre-loaded coil spring 516 for biassing the carriage member towards the upper extreme of its range of travel, so that the workpiece can be biassed against the blocking wheel 200. The carriage member 514 is mounted on the bearing shafts 510 and 512 via linear ball bushes 518 and 520 so as to be easily slidable with respect thereto. A spring retaining sleeve 522, fixed with respect to the bearing shafts, retains the base part of the coil spring 516.

The reciprocating mount 502 comprises generally a cylindrical mandrel 530 fastened to the carriage member 514 by a socket grub screw 532 so as to moveable with the carriage member, a workpiece support member 534 which is both slidable along the mandrel, as well as rotatable with respect thereto, via drawn cup needle roller bearings 536 and 538, and two sleeve-shaped rollers 540 and 542 mounted coaxially on a spindle 544. Excess sliding of the support member 534 is prevented by circlip 545. The rollers 540 and 542 are mounted on the spindle via two pairs of drawn cup needle roller bearings, only one pair of which is visible in the figures, which pair is denoted 546. The two rollers are retained on the spindle with circlips 548 and 550 at each end of the spindle, the spindle itself being retained in a bore in the mandrel.One end of the workpiece support member 534 abuts the rollers 540 and 542 so as to be in rolling contact therewith; this end is specially shaped in a manner to be described shortly.

The workpiece, which is denoted in Figures 11 and 12 as "W", may have a base which is not flat, for instance as shown in Figure 11. If so, it may be desirable to mark the workpiece with a band which, instead of being straight, follows approximately the contour of the base or some other intermediate shape. This is achieved in the present embodiment of the invention by providing one end of the workpiece support member 534 with a shape corresponding, for example, to the shape of the base of the workpiece.

In operation, the workpiece, which is fitted onto the remote end of the workpiece support member 534, comes into engagement with the rotating blocking wheel 200 so that the workpiece and the support member are both caused to rotate together. The support member is biassed against the rollers 540 and 542 by a polycarbonate spring 552 which bears against the workpiece. Hence rotation of the blocking wheel, and thus the workpiece, causes reciprocation of the workpiece as the shaped end of the support member rotates against the rollers. Hence the reciprocating mount operates on a camming principle. The polycarbonate spring 552 is bolted to the main frame of the marking apparatus.

It is not essential that the workpiece support member 534 has the same shape as the base of the workpiece. For instance, the base of the workpiece might be flat, and the support member might be shaped so as to cause a wavy or similar pattern to be marked onto the workpiece.

The tipping arrangement 504 comprises generally a support frame 560 for supporting the carriage assembly and two brackets 562 and 564 to which the support frame is pivotally attached by means of a hard ground rod 566, washers 568 and 570 being interposed between the brackets and the support frame. The brackets, made from mild steel angle, each have two locating dowels 572 and 574 which fit into holes in the rotary indexable table 18 to prevent rotation of the brackets, and are fastened to the table by socket cap screws 576 and 578. The support frame 560, in the form of a wide channel section aluminium block, mounts the two bearing shafts 510 and 512, these being attached to the frame with circlips 580. The spring retaining sleeve 522 is threadedly engaged with the support frame 560.

The angle of tip of the workpiece axis with respect to the blocking wheel 200 is set by means of adjustment screw 582 which abuts the table 18 and is biassed onto the table by tension spring 584, which is wrapped around the spring retaining sleeve 522 and is secured to the table by spring retaining screws 586 and 588.

It will be understood that the configuration of the workpiece fixture arrangement is such that the blocking wheel 200 is required to be on a longer shaft than would otherwise be necessary.

It will be understood that the present invention has been described above purely by way of example, and modifications of detail can be made within the scope of the invention.

Each feature disclosed in the description, and (where appropriate) the claims and drawings may be provided independently or in any appropriate combination.

Claims (49)

1. A marking apparatus comprising a moveable workpiece fixture for presenting workpieces successively to a marking member arranged to cooperate with the workpiece presented thereto, all powered functions of the machine being electrically driven.

2. Apparatus as claimed in Claim 1, wherein the fixture is a rotary fixture with a plurality of angularly spaced apart stations each for receiving a workpiece, the machine comprising an indexing device to index the fixture successively to present said stations to the marking member.

3. Apparatus as claimed in Claim 1 or 2 including means for reciprocating the marking member towards and away from the workpiece.

4. Apparatus as claimed in Claim 3 including an electric motor for driving the reciprocating means, and control means for controlling the electric motor and having switch means for switching the motor on and off, the control means being arranged to control the motor such that, when it is switched off, the marking member is positioned away from the workpiece.

5. Apparatus as claimed in Claim 3 or 4, wherein the fixture and the reciprocating means are driven by a single electric motor.

6. Apparatus as claimed in any of the preceding claims, including an electric motor for driving the marking member, the motor being arranged to rotate continuously during operation of the apparatus.

7. An indexing device for a rotary workpiece fixture or the like comprising a rotatable driven member, a driving member adapted to rotate and periodically to engage the driven member and rotate it through a predetermined angle from one indexing station to the next, the driving member also being arranged to locate the driven member at each said indexing station whilst continuing to rotate.

8. A device as claimed in Claim 7, wherein one of the driven member and the driving member comprises a plurality of radially extending slots or projections equally angularly spaced about its axis of rotation, the other member comprising either a projection or a slot spaced from the axis of rotation of the said member and adapted periodically to engage a said slot or projection respectively whereby the driving member rotates the driven member through the predetermined angle.

9. A device as claimed in Claim 7 or Claim 8, wherein the driven member is provided with a plurality of said slots and comprises an arcuate recess in its periphery between each slot, the driving member being spaced from the driven member and comprising a portion of arcuate form of radius such as to be closely received within a said recess in the driven member whilst rotating, whereby to locate the driven member at an indexing station, the arcuate portion being disengaged from the recess by further rotation of the driving member to permit rotation of the driven member to the next indexing station.

10. A device as claimed in Claim 7, 8 or 9, wherein the driven and driving members are rotatable about spaced parallel axes.

11. A device as claimed in Claim 9, wherein the projection is disposed on the driving member at a radius greater than that of the arcuate portion thereof, the arcuate portion being defined by a circular structure having a recess in the periphery thereof shaped to permit portions of the driven member defining the slots to pass the driving member, the projections being disposed on the driving member or an axis of symmetry of the recess therein.

12. Apparatus including an indexing device as claimed in any of Claims 7 to 11 and a rotary workpiece fixture, and further including means for ejecting a workpiece from the fixture.

13. Apparatus including an indexing device as claimed in any of Claims 7 to 11, and comprising a rotary fixture having a plurality of angularly spaced apart stations each adapted to receive a workpiece, processing means for performing an operation on a workpiece, the indexing device being arranged periodically to rotate the fixture to present the workpieces at said stations successively to the processing means, the driving member of the indexing device driving the processing means whilst locating the driven member.

14. Apparatus as claimed in Claim 13, wherein the processing means is driven by the driving member via a belt which extends between respective pulleys on the driving member and the processing means, the axes of the pulleys being non-parallel, and a pair of opposed tapered rollers is provided between the two pulleys to guide the belt.

15. Apparatus as claimed in Claim 13 or 14, being a marking machine, the processing means comprising a marking head arranged to reciprocate towards and away from the workpiece presented thereto.

16. Apparatus as claimed in Claim 15, wherein the driving means is powered by an electric motor.

17. Apparatus or an indexing device as claimed in any of the preceding claims wherein the direction of movement of the workpiece fixture is reversible.

18. Apparatus as claimed in any of Claims 1 to 6 or 12 to 17, wherein the workpiece fixture is mounted on a platen, the inclination of which is adjustable to suit the operator.

19. Apparatus as claimed in Claim 3, 15 or any other claim dependent therefrom, wherein the reciprocating movement of the marking member is derived via a crank from the driving member referred to in Claim 3 or other rotating part used also to drive the indexing device.

20. Apparatus as claimed in Claim 1, 15 or any other claim dependent therefrom, comprising a device for feeding a marking tape to the marking member, the feed device for the tape being driven from the drive motion supplied to the marking member.

21. Apparatus as claimed in Claim 1, 15 or any other claim dependent therefrom, comprising a device for feeding a marking tape to the marking member, the feed device including a spiral spring adapted to contact the tape to provide feed tension for the feed device.

22. Apparatus for marking workpieces, comprising a marking member and an indexing device for presenting the workpieces in turn to the marking member for being marked, the indexing device including means for mounting each workpiece so that it can rotate relative to the marking member during marking, whereby the periphery of the workpiece can be marked.

23. Apparatus as claimed in Claim 22 wherein the marking member is a wheel which is arranged to rotate continuously during operation of the apparatus.

24. Apparatus as claimed in Claim 22 or 23, the indexing device being as claimed in any of Claims 7 to 11.

25. A device for marking a workpiece, comprising means for mounting a length of marking tape, a marking member for marking the workpiece with the marking tape, and means for mounting the workpiece so that it can be in rolling cooperation with the marking member via the marking tape, the tape being arranged to be advanced only when the workpiece is in said rolling cooperation.

26. A device as claimed in Claim 25, wherein the marking tape mounting means includes means for pulling the tape in a tape feeding direction and means for applying resistance to the tape to resist the pulling means, the resistance being arranged to overcome the pulling force except when the workpiece is in said rolling cooperation.

27. A device as claimed in Claim 26 wherein the means for applying resistance comprises a spiral spring adapted to contact the tape.

28. A device as claimed in Claim 27 wherein the spring includes an arcuate portion which is curved in the opposite sense to that of the remainder of the spiral, the arcuate portion being adapted to contact the tape.

29. A device as claimed in Claim 26, 27 or 28 wherein the pulling means includes a rotary actuator arranged to drive a take-up spool for the tape via a frictional coupling.

30. A device as claimed in Claim 29 wherein the friction of the coupling is adjustable.

31. A device as claimed in any of Claims 25 to 30 wherein the length of marking tape used to mark the workpiece is adjustable.

32. A device as claimed in any of Claims 25 to 31 wherein the marking member is a wheel.

33. A device as claimed in Claim 32 wherein the wheel is arranged to rotate during operation of the device, and the speed of rotation is adjustable.

34. A device as claimed in Claim 32 or 33 wherein the wheel is coupled to a rotary actuator which is arranged to rotate continuously during operation of the device.

35. A device as claimed in any of Claims 25 to 34 wherein the workpiece mounting means is arranged to mount each workpiece so that it can rotate with respect to the marking member during marking.

36. A device as claimed in any of Claims 25 to 35 wherein the workpiece mounting means and the marking member are arranged to be moveable relative to each other during operation of the device, so that a workpiece not possessing circular symmetry can be marked.

37. A device as claimed in any of Claims 25 to 36 wherein the workpiece mounting means permits rotation of the workpiece about an axis and the marking member is rotatable about a further axis, and, during operation of the device, either the workpiece mounting means permits movement of the workpiece along its axis or the marking member is movable along its axis, or both.

38. A device as claimed in Claim 37 wherein the workpiece mounting means is so arranged that rotation of the workpiece causes the workpiece to reciprocate along its axis in a predetermined manner.

39. A device as claimed in any of Claims 25 to 38 wherein the workpiece mounting means and the marking member are so arranged that the angle between the workpiece and the marking member is adjustable.

40. A marking machine including a marking device as claimed in any of Claims 25 to 39 and an indexing device as claimed in any of Claims 7 to il.

41. Marking apparatus according to any of Claims 1 to 6 including a device for ejecting the workpiece.

42. Apparatus according to Claim 41 as dependent on Claim 5 wherein the ejection device is driven by the single electric motor.

43. Apparatus according to Claim 41 as dependent on Claim 6 wherein said electric motor additionally drives the ejection device.

44. An indexing device according to any of Claims 7 to 11 including a device for ejecting a workpiece from the rotatable driven member, the ejection device being synchronised to eject the workpiece whilst the driven member is located at an indexing station.

45. Marking apparatus substantially as herein described with reference to Figures 1 to 5 or 6 to 8 or 11 and 12 of the accompanying drawings.

46. An indexing device substantially as herein described with reference to Figures 1 to 5 of the accompanying drawings.

47. A device for marking a workpiece substantially as herein described with reference to Figures 6 to 8 or 11 and 12 of the accompanying drawings.

48. A device for ejecting a workpiece substantially as herein described with reference to Figures 9 and 10 of the accompanying drawings.

49. A workpiece fixture arrangement substantially as herein described with reference to Figures 11 and 12 of the accompanying drawings.