US3529542A - Feed apparatus for presses or the like - Google Patents

Description

United States Patent inventor Otto Rasenberger, 5 6] Goppingen, Germany Appl. No.' 735,359 Filed June 7, 1968 Patented Sept. 22, 1970 6368 Assignee Die L. Schuler GmbH, 3368'437 Goppingen, Germany 3444768 Priority June 15, 1967 Germany Sch 40,8119

FEED APPARATUS FOR PRESSES OR THE LIKE 7 Claims, 4 Drawing Figs.

US. Cl. 100/215, 100/282, 226/142, 83/244 int. Cl 1130b 15/30 Field of Search 83/222,

References Cited UNlTED STATES PATENTS Sherman et al.

Scheffey Groll Bennet McGara et al Primary Examiner-Billy J. Wilhite A ttarney Craig, Antonelli, Stewart and Hill ABSTRACT: Feed mechanism for step-by-step feed of metal strip or sheet to a press or like machine comprises means for varying the effective length of the step-by-step feed by introducing between the crank drive and the drive shaft for the feed rollers a four-point linkage, including a series of levers, one which is fast on the drive shaft, another lever being anchored to a fixed position, which is adjustable so that by adjusting the same the angular displacement of the drive shaft for each stroke of the crank can be increased or decreased.

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\ 5 H mih jNVENTOR. 0770 RA SEA/B ERGEK A TTURIVEYS FEED APPARATUS FOR PRESSES OR THE LIKE This invention relates to a feed mechanism for step-by-step feeding of metal strip, or other sheet material in presses and stamping or like machines. More particularly it is concerned with a roller feed mechanism, in which a drive shaft has imparted to it a reciprocatory rotary motion through a given angle, the driving motion being derived from a crank drive.

In known feed mechanisms of this type the crank drive acts directly on a rock arm fast on a drive shaft. In these known drives however the angle of rotation of the rockarrn is restricted to about 90 because should this angle be exceeded, the transmissionangles between the connecting rod and the rock arm become so unfavourable that the; stresses that occur very rapidly attain prohibitive amounts. This limitation in the angular displacement to about 90", which occurs in practice is very inconvenient particularly when appreciable lengths of material are to be handled, because a further-transmission ratio must then be applied downstream of the drive shaft, thereby greatly enlarging the movement initiated, so that the feed mechanism, e.g. a feed roller, providesthe desired feed length. Since gearing is generally used for this transmission ratio, the feed mechanism becomes complicated and costly to manufacture. In addition, play is increased by each gear train in the power drive.

To obviate this disadvantage, the invention comprises the introduction of a four-point linkage drive between the crank drive and the drive shaft.

This arrangement has the advantage that, since the fourpoint linkage drive performs a circular movement about its fixed points, substantially larger angular movements of the rock arm and consequently larger angles of rotation of the drive shaft becomes possible. The arrangement according to the invention permits of operating at angles of up to about l 8 ()f without t hg transmission giggles becomirrg-sounfavourable that the forces occurring attain prohibitive amounts. In

many cases such angular, movements are already sufficient toachieve the length of feed required in practice. If this is not the, case for larger feeds, the feed may be still further increased by inserting a relatively small step-up means downstream of the drive shaft.

The invention further relatesto feed mechanisms of the above described type which are adjustable in height in relation to the position of the crank drive in the-press for the purpose of correcting the height at which the strip enters the press tools, and/or in which the length of the feed step is adjustable. In known feed plants these adjustments can only be made when a machine is stationary. For thepurpose of varying the length of the feed step in existing machines the effective crank radius or the effective length of the rock arm is varied, which means that when making a height adjustment on the feed mechanism the effective length of the connecting rod requires a corresponding adjustment. In feed apparatus of this type drives have however been proposed which permit a fine adjustment when in operation. These known fine adjustments are costly and in addition the carryingout of the adjustment during operation, that is to say while the parts in question are performing a movement, presents certain difficulties. Great importance must be attached to effective securing of the individual parts in their adjusted position, and without there being any risk of these parts getting out-of-adjustment during operation, which would necessitate readjustment. When an apparatus is stationary this fasteningeg. tightening of clamp screws is relatively simple and makes certain of retaining the, parts in the adjusted position. During operation however such fastening screws cannot properly be tightened. These. fine adjustments are important because experience has shown that if any change in the stroke rate occurs the length of the feed step will vary because of the alteration of acceleration of masses.

The further problem underlying the invention therefore comprises improving known feed mechanism to overcome these disadvantages.

In one embodiment of the invention the position of the fixed point of the four-point linkage drive ismade adjustable. By

varying the position of the fixed fastening point of the fourpoint linkage drive, its amplitude of oscillation and consequently the length of each feed movement or step can be adjusted. Since the four-point linkage drive performs oscillating movements about its fixed point and the drive shaft, the oscillating movement can be commenced within a relatively large angular range without critical transmission angles for the forces occurring. The magnitude of the oscillating movement does not, vary to any great extent in dependence on the commencement of the oscillating movement. When the four-point linkage drive is inserted between the crank drive and the drive shaft, the distance between the crank drive and the drive shaft can therefore be varied within certain limits, and the smaller variations in the length of feed step then occurring can be compensated byaltering the, base length and/or also altering the position of the base. The particular advantage of this construction lies in the fact that the fixed point of the linkage remains stationary when in operation so that' its position can bechanged even though the mechanism is in motion. For example, this fixed point of the linkage, that is to say the bearing pin for a push rod in the four-point linkage drive, can be secured e.g. on a sliding block, in a guide, or may be disposed eccentrically on a disc, the angular position of which is adjustable by means of a worm drive acting through the periphery of the disc, or by other means. This fixed point can thus in the simplest possible manner be so arranged that'its position is bothadjustable and can be secured when the I machine is operation.

In one embodiment of the invention the crank drive is so disposed that the path (connecting loop), through which the crank rod pivot remote from the crank disc, passes during the working stroke is elongatedand extends in a direction corresponding approximately to the direction of the alteration in position of the feed mechanism on correction of the entry height. Favourable dimensions and force ratios are moreover obtained if in an embodiment of the invention the base of the four-point linkage extendsapproximately parallel to the elongated connecting rod loop.

In one construction a push rod, which is pivoted at one end to the connecting rod connecting the crank rod pivot remote from the crank disc to the rock arm and at the other end to the fixed point, is longer than the rock arm fastened on the drive shaft. Particularly favourable conditions, and in particular very favourable transmission angles, are thereby obtained.

In another construction the push rod is pivoted to the connecting rod at a point which, viewed from the fixed point, is

" situated on the far side of the'connecting line between the crank rod pivot and the pivotal connection of the connecting rod to the rock arm, namely closer to the crank rod pivot than to the swivelling arm articulation.

The invention is illustrated in the accompanying drawings, in which features may be applied singly or in combinations in an embodiment of theinvention, and FIG. 1 is a rear view of a press having feed mechanism, the scale on which the press frame is shown being substantially smaller than the scale on which the feed mechanism is illustrated.

FIG. 2 is a side elevation corresponding to FIG. 1.

FIGS. 3 and 4 are diagrammatic views showing the geometrical conditions of the drive and the positionof the individual members of the mechanism invarious phases of operation.

FIG. 4 is a view similar to FIG. 3, showing theindividual parts in the position which they assume after adjustment in height of the feed mechanism.

Referring to FIG. I, there is shown a hydraulic press including a main frame indicated generally at 1, having a ram 10 and press table 11, on to which is advanced a metal strip shown in dot and dash lines at 9. Mounted in an end arm of the frame is a main shaft 2, which extends transversely of the frame I, a crank disc 3 having a crank pin 4 the position of the crank pin from the axis of the shaft 2 being adjustably suitable fastening means. A crank rod 5 which extends over substantially the entire height of the press, connects the crank 4 to a feed mechanism 6 including rollers 7 and 8 for advancing the strip 9 of material step-by-step into the press between the ram 10 and table I I.

The roller feed mechanism 6 is attached to the frame 1 by means such as slots 12' to permit of vertical adjustment, its height being adjusted by means of screw jack 12 and lock nut 13 to enable the gap between the rollers 7 and 8 to be set at exactly the right height, in relation to the tool (not illustrated), for the insertion of the strip 9. Drive from the lower end of the crank rod 5 is transmitted through a pin 14 to a coupling rod 15, whose other end is connected at 20 to the free end of a rock arm 16 keyed on a drive shaft 18. A push rod 17 is pivotally connected at 26 to rod and at its other end through an eccentric pin 21 on a disc 22, which is mounted for rotation on a shaft 19 forming part of the feed mechanism 6.

The angular position of disc 22 on shaft 19 is manually adjustable by a hand wheel 25 on a spindle 24 provided with a worm 23 acting on the toothed periphery of disc 22. Provision is made for fixing the hand wheel 25 in its various positions by means of a device (not shown). Viewed from the bearing pin 21, the pivot 26 lies (in the example illustrated) on the farther side of a line connecting the fulcrums l4 and and is at a shorter distance from the fulcrum 14 than from fulcrum 20. The push rod 17 is about twice as long'as the distance between the pivot point 20 and shaft 18. The parts 15, 16, and 17 form a linked quadrilateral, the base of which is the connection of the points 18 and 21. The reciprocatory motion of the crank I rod 5 is transmitted to the rock arm 16 through the linked quadrilateral, the fixed point of which is formed by the bearing pin 21, so that the shaft 16 rotates to-and-fro through a predetermined angle of rotation during the oscillation of the crank rod 5. Mounted on the shaft 18 there is a freewheel drive 27 which is constructed after the style of a clamp detent mechanism and which transmits the rotation of the shaft 18 in one direction of rotation to a skew gear 28 in mesh with a gear 29 from which drives is transmitted to roller 8 through a shaft 30. The gear 29 meshes with a gear 31 on a shaft 32 which carries the roller 7.

The drive shaft 18 has an extension 33, which transmits the reciprocatory movement to a second roller feed mechanism.

38 disposed at the outlet side of the press. This roller feed mechanism 38 has the same gears 28, 29, and 31, so that the operation of the two pairs of rollers on both sides of the press is synchronised.

By turning the hand wheel 25, the position of the eccentric bearing pin 21 on disc 22 and thus the fixed point of the fourbar linkage drive can be adjusted and consequently the base of the four-point linkage drive is varied. This variation in turn effects a variation of the amplitude of oscillation of the arm 16 and consequently a variation in the length of the effective feed motion, without the machine having to be stopped.

The geometrical conditions of the linkage movement are illustrated in FIGS. 3 and 4. The crank disc 3 rotates uniformly with the eccentric shaft 2. The distance between the pin 4 and the axis of the shaft 2 constitutes the crank radius 34, which can be adjusted from zero to its maximum value. By making this adjustablility the coarse adjustment of the feed step length is effected. This adjustment is made while the machine is stationary. The crank rod 5 transmits its oscillatory movement to the connecting rod 15. Provided that the bearing pin 21 is in the bottom position as illustrated, the pivot 14 travels through a flat, elongated connecting rod path 35. The parts 5, l5, l6, 17, when the crank pin 4 is in the bottom dead centreposition, take up as shown in full lines in FIG. 3, the position of the same parts in the top dead centre position 4' of the crank pin 4 being shown in broken lines, while the top extreme position of the pivot 14 at the top end of the connecting rod path 35 is designated by 14'. In its position 26' corresponding to the other extreme position the pivot 26 describes an arc of a circle about the fixed linkage point 21. In its path to the position 20' the pivot 20 describes an arc of a circle about the shaft 18, the shaft 18 rotating through the angle If rotation through the angle a is now effected by means of the handwheel 25, the fixed point 21 moves into its position 21". Under these conditions (i .e. as illustrated) there will be no change or only a slight change in the position of the point 26, which corresponds to the top dead centre position of the crank. On the other hand, the position of the connecting rod 15 corresponding to the bottom dead centre position of the crank is different. In the bottom dead centre position of the crank the pivot 14 is situated in position 14", the pivot 26 at the position 26", and the 'pivot 20 at the position 20".

It will be seen therefore that the position of the pivot 20 corresponding to the top dead centre position does not vary when the fixed point 21 is moved, but that its position corresponding to the bottom dead centre of the crank is at a distance corresponding to the angle A from the position of the pivot 20 wlfehthe fixed point ii remains unchanged. The amplitude of oscillation of the rock arm 16 is therefore greater by the angle in the case of th e fixed point 21". In the oscillating movement about the fixed point 21", therefore the pivot 26 describes an arc of a circle 36 and the pivot 14 a connecting loop 36.

By varying the position of the fixed point 21 therefore the angular movement of the arm 16 can be varied without the crank radius 34 being changed. This alteration of the position of the fixed point 21 can be effected during operation, that is to say while the parts are moving, since the fixed point 21 is at rest during this movement. An alteration in the swivel angle in turn entails an alteration in the distance, by which the strip 9 is advanced into the press by the rollers 7 and 8 or drawn out of the press by the feed mechanism 38.

The distance of the fixed shaft 19 from the axis of the crank disc 3 is designated in FIG. 3 by H In FIG. 3 it is assumed that the feed mechanism is at its maximum distance from the axis of the crank disc 3, that is to say it has assumed its lowest possible position.

""155 conditions illustrated in FIG. 4 differ from those illustrated in FIG. 3 in that with the same geometrical dimensions of the parts 5, l5, l6, and 17 the distance H of the fixed shaft 19 from the axis of rotation of the crank disc 3 is smaller than the corresponding distance H in FIG. 3. The feed mechanism should therefore be at its shortest possible distance from the crank disc 3, that is to say it has been moved to its highest position by adjustment of the adjusting screw 12. The positions of the parts 5, 15, 16, 17, corresponding to the fixed point 21, in the bottom dead centre position 4 of the crank are shown in solid lines, while the corresponding positions when the crank is in the top dead centre position 4' are shown in broken lines. The position of the parts, corresponding to the bottom dead centre position 4, when the fixed point 21" has been displaced by the angle a is in turn shown in chain-dotted lines. It will be seen that when the feed mechanism is at a distance H from the crank disc, the angle I is also increased by the angle A on displacement of the fixed point in a direction parallel to the connecting rod loop, so that the length of the feed movement can be varied by such a dis placement of the fixed point 21. The connecting rod paths 35 and 37 in FIG. 4 are slightly displaced in relation to those shown in FIG. 3. The feed length is thereby very slightly altered. Through the adjustment of the entry height, that is to say the raising or lowering of the feed mechanism with the aid of the height adjusting screw 12, the length of the feed movement therefore varies only to a very slight amount. This slight alteration can however immediately be corrected by the fine adjustment correction means according to the invention, namely by slightly adjusting the fixed point 21 of the linkage with the aid of the handwheel 25.

It should be understood that only those parts which are essential to an understanding of the invention are shown in the drawings. The brake devices, with which such roller feed apparatuses are generally equipped, the brake release devices, and the likeare not mentioned because they are sufficiently well known.

As explained above, when the height of entry of the strip is varied it may be advantageous to adjust the base of the fourpoint linkage drive. The adjustment of the base of the fourpoint linkage is particularly important when making a variation in the length of the feed motion, particularly when on the alteration of the stroke rate the length of the feed motion is unintentionally altered in consequence of the mass forces and the exact length of the feed corresponding to the tool must be readjusted by varying the position of the fixed point in the foui -pointli'nka'ge i w lclaim:

1. In a press machine having a press tool and a feed mechanism for the step-by-step feeding of material to the press tool, wherein the length of the step-by-step feeding is adjustable, said feed mechanism including a drive shaft for being oscillated in a toand fro-manner so as to effect a selected angle of rotation, a crank drive operatively connected with the main shaft of the press machine, a four-point linkage for transmitting motion from said crank drive to said drive shaft, a connecting rod operatively connecting said four-point linkage and said crank drive, said four-point linkage including two fixed points, one of said two fixed points being selectively adjustable connecting rod.

2. A press machine as claimed in claim 1 in which the fixed end of the third lever is pivotally mounted on an angularly adjustable member and means for adjusting the angular position of said member in order to adjust the position of said third lever.

3. A press machine as claimed in claim 1 wherein the crank drive is so disposed that the path followed by the pivot connecting the first lever to the crank drive is elongated and ex tends in a direction corresponding approximately to the plane in which the feed mechanism is adjustable when adjusting the position at which the material enters the tool.

4. A press machine is claimed in claim 3 in which the pivotal axis of ,the second lever and the fixed position of the third lever are located on a base line that extends substantially parallel to the elongated path followed by the pivotal connection of the first lever with its crank drive.

5. A press machine as claimed in claim 1 comprising a third lever having a length which exceeds that of the second lever.

6. A press machine as claimed in claim Sin which the length of the third lever is not substantially less than twice that of the second lever.

7. A press machine as claimed in claim 1 comprising a third lever having its point of connection to the first lever located on that side of a line passing through the pivotal connections of the first lever respectively with the third lever and the crank rdrive remotefrgm the fixed end of said lever.

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