This invention relates to a drive for a blanking press roll feed for feeding a strip of stock material.

Repetition pressing as is commonly performed, eg. on a multi-station transfer press, requires as a first stage the production of blanks from a strip of stock material. It is desirable to minimise material cost by obtaining as many blanks as possible from a given area of strip. This is achieved by punching the blanks out in two or perhaps three rows from a strip of appropriate width. When round blanks are required, two-row blanking can save about 8% of material compared to single-row, and three-row blanking can save about 11%.

Two and three-row blanking can be achieved by passing the stock material more than once through the blanking press, but this requires the partially-used stock to be rewound and then presented accurately once or twice more to the press. This is time consuming and not always fully effective.

Alternatively, multiple blanking punch and die sets can be used side by side but this requires a large and more complex and expensive press.

The remaining method is to feed the stock through the blanking press in zig-zag or staggered fashion so that a single punch can cut all the blanks in a single pass. Whilst it is possible to achieve this by a CNC-based solution employing stepper motors, there is still a demand for robust and simple machines which are reliable and do not require support by highly-trained maintenance personnel.

A known mechanically-driven stagger feed employs a pair of feed rolls which draws the stock through the blanking press. The rolls are pivotally mounted about an axis perpendicular to the plane of the nip of the rolls through which the stock passes. The rolls are oscillated about this axis in synchronism

with the stepwise rotation of the rolls through an angle sufficient to throw the stock through a defined arc as it passes through the blanking press, thereby presenting the stock to the blanking tool in the desired staggered path.

Whilst achieving economical blanking, this device has the disadvantage that the feed rolls must be spaced by a significant distance from the blanking press so as to limit the angle through which the stock is thrown; otherwise if the feed rolls are downstream of the press excessive space must be left upstream of the press to accommodate the sideways movement of the stock. If the feed rolls are upstream of the press so that the stock is propelled rather than pulled through the press, the scrap may be chopped immediately it issues therefrom, so the problem is avoided. However, because the rolls act upon the unblanked stock, there is then another problem in that it is possible that the surface of the blanks produced may be marked, which is unacceptable if a high-quality finish is required in the end product.

Another known stagger feed used in multi-station transfer presses employs feed rolls which are oscillated axially of themselves between two positions; only two-row blanking is provided. Furthermore the stepwise angular rotation of the rolls and their axial reciprocation are derived separately from different shafts of the press.

The present invention, at least in its preferred embodiment, seeks to avoid at least some of the limitations of the known feed drives and in addition to provide a mechanical drive for a roll feed which may be retrofitted to existing presses without major modifications.

In one aspect the invention provides a mechanical drive for a blanking press roll feed in which the feed rolls are moveable axially of themselves to effect staggered feed of stock material through a blanking press, the drive comprising an input adapted to be mechanically driven from the blanking press

and means for deriving from the input a first motion convertible into a cyclic stepwise axial movement of the feed rolls and a second motion convertible into stepwise rotation of the rolls, the first and second motions being synchronised to effect said staggered feed.

Preferably the first motion provides three axial positions of the feed rolls to effect three-row staggered feed of the stock material.

In another aspect the invention provides a mechanical drive for a blanking press roll feed in which the feed rolls undergo stepwise angular rotation and are moveable axially of themselves to effect staggered feed of stock material through a blanking press, the drive comprising an input adapted to be mechanically driven from the blanking press, means for deriving from the input a motion convertible into cyclic stepwise axial movement of the feed rolls between three positions to effect three-row staggered feed and means for adjusting the amplitude of the cyclic axial movement whilst maintaining the mid-position thereof fixed relative to the blanking press.

There may be means for adjusting the amplitude of the stepwise angular rotation of the feed rolls whilst maintaining equal the amplitude of successive steps.

Thus, in a further aspect the invention provides a mechanical drive for a blanking press roll feed in which the feed rolls undergo stepwise angular rotation and are moveable axially of themselves to effect staggered feed of stock material though the blanking press, the drive comprising a rotary input adapted to be mechanically driven from the blanking press, means for deriving from the input a reciprocating motion of fixed amplitude, means for converting said motion into stepwise angular rotation of the feed rolls, and means for varying the amplitude of the steps of angular rotation whilst maintaining the amplitude of successive said steps equal.

The motion or motions may be derived from a single rotary cam shaft. Preferably the first and second motions are derived via a single cam follower assembly.

The follower assembly may comprise a slide, the first and second motions being derived therefrom by respective pivoted levers.

The camshaft may be adapted to receive interchangeable cams having different profiles so that two-row or three-row staggered feed may be effected.

For three-row staggered feed the camshaft may comprise a pair of axially-spaced cams, the follower assembly comprising two roller followers contacting respective said cams at 180° to each other, one or other of the followers always being positively driven by the cams.

One cam of said pair may be removable and replaceable at the same axial location by a cam profiled to effect two-row staggered feed, the position of the roller follower of the other said cam of the pair being axially adjustable to be aligned with the replacement cam so that it is contacted by both roller followers.

The second motion may be provided from its respective pivoted lever via a crank formed with said lever and a unidirectional clutch.

The first motion may be provided from its respective pivoted lever by a crank formed with said lever, the throw of the crank being adjustable to vary the amplitude of the axial movement of the feed rolls and the effective length of a connecting rod from said crank to linearly moveable structure carrying the feed rolls being adjustable.

The converting means may comprise a crank mechanism, the amplitude varying means comprising means for adjusting the effective throw of the crank mechanism.

The amplitude varying means may also comprise means for adjusting the

mean angular position of the crank mechanism relative to its pivot axis.

The amplitude varying means may also comprise means for adjusting the length of a connecting rod of the crank mechanism.

The means for adjusting the mean angular position may comprise an eccentric whereby a pivotal connection of a connecting rod to a crank arm is displaceable non-radially of the pivot axis.

The drive may comprise a housing, the input being a rotary shaft, the housing being configured for mounting on the blanking press with the axis of the input shaft parallel to the axis of rotation of the blanking press drive shaft.

The input shaft may have a positive mechanical drive the speed of which relative to the press is adjustable by substitution or otherwise to permit variation of the feed pattern.

The invention also includes a roll feed and a blanking press provided with a drive as set forth above.

The invention will now be described merely by way of example with reference to the accompanying drawings, wherein:

Figure 1 is a view of a part of a transfer press, the blanking stage of which is provided with a roll feed, shown diagrammatically;

Figure 2 is a side elevation of a roll feed, viewed from the front of the press of Figure 1 ;

Figure 3 is an end view of part of the mechanism of Figure 2;

Figure 4 is a sectional side elevation of the mechanical drive for the roll feed arranged for 3-row feeding;

Figure 5 is a sectional end elevation of the drive on line A-A of Figure 4;

Figure 6 shows part of the drive of Figures 4 and 5;

Figure 7 shows the required arrangement of blanks in three-row stagger feeding; and

Figure 8 and 9 illustrate the geometrical considerations which are taken into account when the axial stroke of the feed rolls is adjusted.

Referring to Figure 1 , a transfer press has a blanking stage 10 the punch of which acts along axis 11. Stock strip material 12 is drawn through the blanking stage in the direction of arrow 14 by a pair of feed rolls 16,18. As described hereafter the rolls 16,18 are mounted to be moved together axially of themselves as indicated by arrows 19 in a repeating sequence to effect a staggered feed of the strip of material 12. As illustrated, the rolls are moving the strip 12 to effect two-row blanking. The blanks (which may be cupped as well as punched-out at the blanking stage 10) are passed in conventional fashion to the subsequent stages of the transfer press, the next such stage being shown at 20.

The roll feed 16,18 is illustrated as acting on the scrap remainder of the strip 12 after blanking; it could equally be positioned on the other side of the blanking press 10 to act on the unblanked strip and propel it through the press 10. The rolls 16,18 in this example have long-pitch helical grooves 22 on their surfaces to ensure positive transport of the strip, as is known in the art. Pressure is applied to the rolls by a pneumatic cylinder (not shown) and the rolls can be opened and closed by a manually switched solenoid valve (not shown) for exhausting and pressurising the pneumatic cylinder as required.

Referring to Figure 2, the rolls 16,18 are carried in a linearly-moveable carriage 24 and are provided with adjustable stock guides 26 on the input side of the roll nip. A further pair of guides are arranged on the other (front) side of the blanking press to locate the strip before it enters the press. This pair of guides is supported on a slide bar and driven from the carriage by a pivoted link to move in synchronism therewith. The pairs of guides are set to the width of the strip material and ensure that it is accurately positioned in the rolls 16,

18 and moved from side to side about the centre-line of the feed path.

The rolls 16,18 are geared together by a pair of equal-sized gears 28. The lower roll 18 also is provided with an axially elongated gear wheel 30 which meshes with an axially relatively-short gearwheel 32. This enables the carriage 24 to move from side to side whilst the gears 30,32 remain in mesh.

The gear 32 is driven intermittently via a crank 34 (shown about 90° out of position in Figure 2 for clarity) connected via a unidirectional sprag clutch 36. The crank driven by a rod 38 (shown also in Figure 3, and described further hereafter) supplies intermittent angular motion in one or more steps and then returns to its original position, the sprag clutch 36 transmitting the motion in the driving sense, thereby rotating the feed rolls 16, 18 to advance the stock material 12 by the required pitch. On the return motion of the crank 34 the sprag clutch 36 disengages and the rolls remain stationary. A back-stopping or reverse clutch 40 prevents reverse rotation of the rolls 16, 18 which could otherwise occur due to the weight of the strip 12 and a permanently-engaged friction brake 42 prevents over-running of the rolls at the end of the feed cycle due to their inertia.

The carriage 24 is slidabiy mounted via four sliding roller or ball bearings 44 on slide bars 46. Stepwise reciprocating motion parallel to the axis of the feed rolls 16, 18 is provided via connecting rod 48 from a drive unit described below. The connecting rod is connected to the carriage 24 via pivot pin 50.

A damper (not shown) is provided to engage the carriage at each end of its travel to ensure controlled deceleration and reversal without over-travel or uncontrolled oscillation due to the compliance of the drive linkage.

Referring to Figures 4 and 5, the drive unit comprises a housing 52, 55 and 96 containing a horizontal cam shaft 54 running in bearings 56, 58. The housing has a base plate 55 enabling it to be mounted at one end of the press

frame externally thereof with the axis of shaft 54 parallel to the principal shafts of the press. The camshaft may thus conveniently be driven from one of those shafts via a linked chain and a sprocket 60. Clearly other forms of positive mechanical input drive may be employed, for example a toothed belt or gear train.

Mounted on the camshaft 54 for rotation therewith are a pair of cams 62, 64, described further hereafter.

A cam follower assembly comprises a carrier 66 supported on guide rods 70 for vertical reciprocating motion. The carrier is provided with upper and lower roller followers 72, 74 which respectively abut the cams 62, 64 at 180° relative to the axis of the shaft 54. At all times, at least one of the followers 72,74 is driven by its cam, thus preventing overthrow and ensuring that the motion of the carrier 66 is always positively linked to that of the shaft 54.

The lower roller follower 74 is mounted on a fixed shaft 76 and the upper roller follower 72 upon a shaft 78 which can be moved between a right-hand position as shown in Figure 4 in which the follower 72 engages cam 62 and a left-hand position in which the follower 72 may be repositioned to be vertically aligned with follower 74 so that they both may be driven from the same cam, as described hereafter.

The carrier 66 has an integral rod-like portion 68 extending through the top of the housing 52 and which is there pivotally connected at 80, 82 to two pivoted levers, in this embodiment bell-cranks 84, 86 which are respectively mounted on trunnions 88, 90. The pivotal connections 80,82 are mounted in slide blocks 81 ,83 disposed in channels 85,87 extending laterally of the portion 68 to permit the pivots 80,82 to move arcuately about the trunnions 88,90.

The axes of the trunnions 88,90 are at right angles to each other. The axis of trunnion 88 is orthogonal to that of the camshaft 54 (and thus also to

that of the feed rolls 16, 18) so that when the housing 52 is mounted on the press the upper end 92 of the lever moves back and forth through an arc in a plane parallel to the required axial movement of the feed rolls 16, 18. The connecting rod 48 (Figures 2 and 4) is pivotally connected to the upper end 92 of bell crank 84 thereby to transmit this motion to the feed rolls 16, 18.

The pivot axis of the trunnion 90 is parallel to that of the camshaft 54 and to the axes of the feed rolls 16, 18. The arcuate back and forth motion of the free end 94 of bell crank 86 is converted into stepwise rotation of the feed rolls 16, 18 via the connecting rod 38 (Figures 3 and 5).

Thus the stepwise axial movement and stepwise rotation required for the feed rolls to provide staggered feed are both derived from the single mechanical input to shaft 54 via the single motion of carrier 66, and are automatically synchronised.

The cams 62, 64 in Figures 4 and 5 are shaped to provide three-row staggered feed and accordingly the sprocket pulley 60 is chosen so that the camshaft 54 runs at one third of the speed of the press shaft driving the blanking press.

The required axial movement of the feed rolls is divided into six parts of equal duration; forward half the movement, dwell, forward half the movement, dwell, backward the full movement, dwell. The feed rolls rotate the required pitch (the distance between successive blanks in adjacent rows) during each forward movement and remain stationary during the backward or return movement, so that blanks are punched successively from the right, centre and left rows, viewed from the front of the press.

This sequence of movement cannot be derived from a single conjugate cam. Conjugate form (constant diametral width) is necessary if a cam is to be used with two constant-contact followers mounted at 180° to each other in a

common carrier.

It is for this reason that the two cams 62,64 are provided. The composite profile of the operative parts of cams 62,64 is shown dotted at 65 in Figure 5. In operation cam 62 is in contact with follower 72 when the carrier 66 is to be moved upwards and cam 64 is in contact with follower 74 when the carrier is to be moved downwards. Both cams contact their followers during dwell periods of the cycle, ensuring a smooth changeover of the drive from one cam to the other.

The drive unit is designed so that it may easily be converted from three-row to two-row blanking. For this, the sprocket 60 is removable and replaceable by one sized to drive the camshaft 54 at one half instead of one third press speed. A side plate 96 of the housing is detachable to give access to the cams and followers.

Cam 64 is removed by unscrewing retaining nut 98, cam follower shaft 78 is repositioned to the left so as to be supported in bores 99,100 of the carrier 66, instead of in bores 100,101 with cam follower 72 positioned directly above follower 74. A conjugate cam shaped for two-row feeding is then substituted for cam 64. Being conjugate, the cam has a constant diametral dimension, so that the two followers 72, 74 are in contact with the cam at all times and thus the carrier 66 is always positively driven. A suitable two-row cam is symmetrically shaped to provide equal back-and-forth motion of the feed roll synchronised with advance of the stock material by the required pitch.

Figure 6 shows the connection between rod 48 and the end 92 of bell crank 84 in more detail. A means of adjusting the axial stroke of the feed rolls 16,18 is provided so that the pitch of (distance between) the rows of blanks may be varied, thereby permitting blanks of different sizes to be produced most economically.

The end 92 of the bell crank has a slot 103 in which is received a slider 102 having a threaded bore engaging an adjustment lead screw 104 which is rotatable by a hexagonal head 106.

The rod 48 is pivotally connected to the slider 102 via a pivot 107 on a sector plate 108. The pivot is spaced eccentrically relative to a pin 110 in which the plate is pivotally mounted on the slider 102. A locking pin is carried by the slider 102 and projects through an arcuate slot 113 in the sector plate centred on the axis of the pin 110. The angular position of the sector plate on pin 110 can thus be adjusted and then secured by means of a clamping nut 114 carried by the locking pin.

The position of the pin 110 (and hence of the sector plate 108 on which is mounted pivot 107) axially of the lead screw 104 is indicated by a scale 116, which is read at the point where it is intersected by the edge 118 of the sector plate 108. The sector plate itself has an arcuate scale 120 which is read at an index line 122 to indicate the angular setting of the plate.

The connecting rod 48 incorporates separate threaded parts 124,126 screwed together with a locknut 128 to form a turn buckle for adjustment of the length of the rod. Similar threaded parts and a locknut are incorporated in the other end of the rod 48 at the connection of the rod to the carriage 24 at pivot pin 50; at opposite ends of the rod 48 left and right handed threads or threads of the same hand but different pitch may be used. The latter can provide more accurate adjustment because the change in length of the rod 48 per revolution of the part 126 is less.

In Figure 7, there is shown the pattern in which circular blanks are punched from the stock material 12 in three-row blanking. The blanks are equally spaced in each row, the middle row 130 being disposed on the centre line 132 of the strip with the outer rows 134,136 equally spaced on each side.

Transversely the blanks lie in rows, the axes 138 of which are inclined at 60° to the longitudinal centre line 132 of the strip 12, so that each blank forms an equilateral triangle with two neighbouring blanks. This spatial relationship is important for accurate and economical blanking and it is achieved by maintaining the axial stroke of the feed rolls centred about the axis 11 of the blanking press 10 and by feeding the strip 12 through the feed rolls in equal steps by rotation of the feed rolls 16,18.

Referring to Figure 8, the cams 62,64 produce an equal angular excursion (in this case 20°) of the bell crank arm 92 either side of its mean position for the centre row of blanks. When the drive unit of Figure 4 is fitted to the press, it generally will be found that the reciprocating axis 139 of the pivot pin 50 (Figure 2) is offset by a distance 140 (Figure 8) from the line of movement of pivot pin 107. Because of this the 20° excursions of the bell crank 92 (and hence crank arm 142) do not produce equal excursions of the pivot pin 50 (and hence the feed rolls) relative to the axis 11 of the blanking punch 10. As illustrated the excursions are 23.14mm and 24.74mm instead of 23.94mm each. Geometrically, the effective crank arm driving the rod 48 is not the bell crank arm 92 itself, but a line joining the axes of pin 107 and trunnion 88, shown at 142 in Figure 8. The crank arm 142 is shown for convenience in Figure 7 as perpendicular to the reciprocation axis 139 when in its central or mean position; this is not typically the case and this also affects the disposition of the reciprocating motion relative to the punch axis. These errors are compensated and the correct reciprocating motion is achieved by the adjustment facility provided on the bell crank arm 92, as follows.

The required total stroke of the pin 50 is first set by adjusting the effective length of crank arm 142 by moving the slider 102 in the slot 103 by means of the lead screw 104. Then the stroke is equalised about the mid-

position of the bell crank arm by rotating the sector plate 108 about pin 110. This effectively moves the position of the pin 107 sideways relative to the axis of the slot 103, and thus angularly displaces the effective crank arm 142 relative to the axis of the slot. In Figure 9, if the effective crank arm 142 has been moved through an angle 144, in this case 9°46'. This results in the 20° angular movements of the crank arm 142 about its new mean position producing equal and opposite axial movements of the pin 50 of 24.29mm each side of its mid-position.

However the mid-point of the stroke is still displaced by a distance 146 relative to the punch axis; this is corrected by setting the bell crank arm 92 (and hence effective crank arm 142) at its mid-position and then adjusting the length of connecting rod 48 by means of turn buckle 124,126,128, and the similar arrangement at the other end of the rod. Index marks 148,150 (Figure 2) are provided on the feed roll carriage 24 and fixed structure of the press to enable the carriage to be aligned with the punch axis 11 for this purpose. Because adjustment of the sector plate 108 moves the pin 107 longitudinally of the arm 92 as well sideways, a calibration chart may be used to relate the settings on scales 116 and 120 for different required blank sizes on a given machine. The chart may be devised for a each machine by standard trigonometry having regard to the dimensions of the machine. A single implementation of the setting procedure will suffice for most applications, but it may be repeated iteratively if greater accuracy is required or if the calibration chart is unavailable.

The connection of the rod 38 to the end of bell crank 94 is the same as shown in Figure 6. An offset between the line of movement of the pivotal connection 152 of the rod 38 to the bell crank arm 94 and the axis of rotation of crank 34 (Figure 3) will result in the successive angular steps of the feed rolls being unequal. Thus an adjustment and setting-up procedure similar to

that already described is required. A scale may be provided on the crank 34 and an index mark on adjacent fixed structure to facilitate this.

Setting-up procedures for two- row blanking are similar for both the axial motion of the feed rolls and their stepwise angular advance, except that it is not necessary to identify the mid-point of the axial or rotational movement of the feed rolls.

Single row blanking may be performed by disconnecting the roll feed axial drive. Adjustment of the stepwise angular rotation of the feed rolls as described will be necessary for equal pitching, and cams intended for three roll feeding must be replaced by a cam specific for single row or two row blanking.

The sprocket 60 will also require replacement with one appropriate to the replacement cam.

Each feature disclosed in this specification (which term includes the claims) and/or shown in the drawings may be incorporated in the invention independently of other disclosed and/or illustrated features.

The appended abstract as filed herewith is included in the specification by reference.