US2679765A - Wrapping machine - Google Patents

Description

June I, 1954 BROOK WRAPPING MACHINE 3 Sheets-Sheet 1 Filed April 21, 1952 O a. o m x x I U m A o m %0 F 0 L/(\ IWENTO XW Q AWTUENEV June 1, 1954 BROOK I 2,679,765 WRAPPING MACHINE Filed April 21, 1952 3 Sheets-Sheet 2 INVENT R 87 M s M L. BROOK WRAPPING MACHINE June 1, 1954 3 SheetsSheet 3 Filed April 21, 1952 Invv'nfiv Xenia/MO 5! w I Plum ,qTranuEys Patented June 1, 1954 WRAPPING MACHINE Application April 21, 1952, Serial No. 283,333

Claims.

In wrapping machines, it is often desirable to impart oscillating or reciprocating movement to a part (e. g. a lifting plunger) in one direction through a spring and to return the driven part positively, the spring yielding in the event of an obstacle to movement of the driven part and so preventing damage to the mechanism. However, the force applied to the spring in the event of stoppage of the driven part increases the continued movement of the driving member. She spring must not therefore be too strong, otherwise the mechanism may be damaged, despite the provision of the spring, in the event of obstruction of the driven part. On the other hand, the spring must be strong enough to impart positive movement to the driven part under nor mal conditions without bouncing, which is liable to occur at high speeds. It is often difficult in practice to reconcile these conflicting requirements.

With a view to avoiding this difficulty the invention provides, in a wrapping machine, the combination of a driven member mounted to rock about an axis, a driven member mounted to rock about the same axis, a spring disposed between the driving and driven members and serving to impart movement in one direction from the driving to the driven member, the spring being so mounted as to be capable, in the event of obstruotion to movement of the driven member, of changing its line or" action in the direction to reduce the mechanical advantage which exerts on the driven member, and an abutment for positively imparting return movement from the driving to the driven member. The spring will, of course, yield in the event oi obstruction of the driven member, and become stronger as a result of continued movement of the driving member, but its mechanical advantage will progressively decrease. Consequently it is possible to use a spring which is strong enough to resist bouncing without risk of damage to the mechanism when the driven member is obstructed, and without imposing undue loading on the parts which impart rocking movement to the driving member.

One specific application or" the invention, which will shortly be described in detail, is to the lifting plunger in a bunch wrapping machine of the kind described in my copending U. S. application Serial No. 283,332, but the invention is equally applicable to the lifting plunger of a twist wrapping machine or to other parts of wrapping machinery, e. g. to a picker for pulling a web of wrapping material into position above the lifting plunger or to mechanism for moving a heat sealing member wrapped article.

The above mentioned specific application of the invention will now be described in detail, by Way of example, with reference to the accompanying drawings, in which:

Fig. 1 is a side elevation of a bunch wrapping machine for wrapping confectionery,

Fig. 2 is a side elevation, on a larger scale, of the mechanism for actuating the lifting plunger or the machine, and

Fig. 3 is a view similar to Fig. 2 but showing the parts in the positions which they assume when upward movement of the lifting plunger is obstructed.

The machine shown in Fig. 1 is described in more detail in U. 5. application Serial No. 283,332 and it will be sufficient to explain here that a web it of wrapping material is fed from a reel H, by a picker not shown, over rollers 52 and i3 and thence over an adjustable feed table past a pair of cutting knives. These are periodically actuated, by a cam-operated bar 55, to sever a wrapper from the leading edge of the web. One of the severed wrappers is indicated at it in Fig. 2. A second reel ill of wrapper is provided for use when the reel i i is exhausted.

The picker is operated by a bell crank 16, which is periodically oscillated, by a cam actuated driving lever 1?, to impart reciprocating movement to the picker. A link 9 is periodically raised and lowered, by means of a lever l8 operated by another cam, to open and close the picker jaws at the proper tirnes. The lever 13 is coupled by a linkage i9 and a rod 2% to a clamp 2|, which is lowered to clamp the web of wrapping material while the knives are operating and is moved to inoperative position when the picker jaws close to feed the web of wrapper forward.

Ihe tablets to be wrapped are fed by hand into recesses 23 in a horizontal feed disc 2 which is intermittently rotated to bring the tablets in succession into position above a lifting plunger 25. This is periodically lii ted, as later described, to lift a tablet, and a wrapper it which has been fed into position above it, through an annular brush contained in a member 2? and into a pair of grippers 28 on a carrier head 29, a cam-operated top plunger 3% having previously descended through the brush to press the wrapper against the tablet during its transit through the brush. She carrier head 23 is intermittently rotated and the wrapping of the tablets is completed on the carrier head as described in U. S. application Serial No. 283,332.

The lifting plunger 25 is mounted, as shown in,

into contact with a Fig. 2, on the upper end of a bar 26, supported by two pivoted links, the upper link 3| being periodically rocked by a cam 33 to raise and lower the plunger and the lower link 32 serving to control the plunger so that it executes an approximately straight line movement. It is necessary that the plunger should be spring driven in the upwarddirection so that it may come to rest if it meets an obstruction, e. g. if a tablet should fall off the plunger and foul some part of the machine. A positive return movement is necessary to make sure that the plunger is fully withdrawn below the feed disc before the latter starts to rotate.

The upper link 3| is pivoted on a rocking shaft 34, to which is fixed an arm 35 carrying a follower 36 which coacts with the cam 33 to rock the shaft 34. Fixed to the shaft 34 is a bell crank 31 and a compression spring 38 is mounted between the lower arm of the bell crank 37 and the undersurface of the link 3|. An adjustable screw 39, depending from the upper arm of the bell crank, bears against the upper surface of the link 3| and serves to impart positive return movement to the plunger 25. Adjustment of the screw 39 also serves to effect vertical adjustment of the plunger 25 in relation to the feed disc 24.

The spring 38 surrounds a rod 46 and is mounted in compression between trunnion blocks 4|, 42 on the rod 40. The lower trunnion block 42 is fixed to the rod 46 and its trunnions 43 engage slots 44 in the lower arm of the bell crank 31. The upper trunnion block 4| is slidable on the rod 43 and its trunnions 45 engage slots 66 (see Fig. 3) in the lower edge of the link 3|. The upper trunnions 45 are nearer the centre of the rocking shaft than the lower trunnions 43.

If the plunger 25 meets an obstruction, the link 3| will cease to move. Continued upward movement of the lower arm of the bell crank 3'! will then, as shown in Fig. 3, cause the rod 40 to pivot about the arrested upper trunnions 45, and as the lower trunnions 63 continue to move in an are about the centre of the rocking shaft 34, the line of action of the spring 38 will be changed, becoming progressively more nearly radial to the rocking shaft 34. Despite, therefore, that the spring 38 becomes stronger as it is compressed, its mechanical advantage becomes progressively smaller, so avoiding risk of damage to the mechanism and reducing the loading on the cam 33 and bell crank 31.

What I claim as my invention and desire to secure by Letters Patent is:

1. In a wrapping machine, the combination of a pivotally mounted driving member comprising an arm projecting from its pivotal axis, means for periodically rocking said driving member to perform a forward stroke away from a home position followed by a return stroke, a driven member mounted to pivot on the same axis as said driving member and comprising an arm projecting from said pivotal axis, said driven member being normally movable without obstruction about said pivotal axis through the same are as said driving member, a spring disposed between said arms for imparting movement from the driving member to the driven member during the forward stroke of said driving member, said spring being disposed so that during the initial stage of its forward stroke the portion of the arm on said driving member adjoining said spring moves substantially in the axial direction of said spring, connecting means between said spring andsaid arms which permit, in the event of obstruction to movement of the driven member during the forward stroke of the driving member, movement of the spring from its initial position in relation to said arms in the direction to bring its line of action progressively nearer a position radial to said pivotal axis, and an abutment for positively imparting movement from the driving member to the driven member on the return stroke of said driving member.

2. In a wrapping machine, the combination of a pivotally mounted bell crank, a cam, means actuated by said cam for periodically rocking said bell crank to perform a forward stroke away from a home position followed by a return stroke, a driven member mounted to pivot on the same axis as said bell crank, said driven member being normally movable without obstruction about said pivotal axis through the same arc as said bell crank, a compression spring disposed between one arm of said bell crank and said driven member for imparting movement from the bell crank to the driven member during the forward stroke of the bell crank, said spring being disposed so that during the initial stage of the forward stroke of said bell crank the portion of said arm adjoining said spring moves substantially in the axial direction of said spring, connecting means between the spring, said arm and said driven member which permit, in the event of obstruction to movement of said driven member on the forward stroke of the bell crank, movement of said spring from its initial position in relation to said arm and driven member in the direction to bring its line of action progressively nearer a position radial to said pivotal axis, and an abutment on the other arm of said bell crank for positively imparting movement from the bell crank to the driven member on the return stroke of said bell crank.

3. In a wrapping machine, the combination of a pivotally mounted bell crank, a cam, means actuated by said cam for periodically rocking said bell crank to perform a forward stroke away from a home position followed by a return stroke, a driven member mounted to pivot on the same axis as said bell crank, said driven member being normally movable without obstruction about said pivotal axis through the same arc as said bell crank, a compression spring disposed between one arm of said bell crank and said driven member for imparting movement from the bell crank to the driven member during the forward stroke of the bell crank, said spring being disposed so that during the initial stage of the forward stroke of said bell crank the portion of said arm adjoining said spring moves substantially in the axial direction of said spring, a rod disposed inside said spring, a first trunnion block fixed on one end of said rod and carrying trunnions which are accommodated in slots in said arm, a second trunnion block mounted to slide on the other end of said rod and carrying trumiions which are accommodated in slots in said driven member, said first trunnion block being located further from said pivotal axis than said second trunnion block, and an abutment on the other arm of said bell crank for positively imparting movement from the bell crank to .the driven member on the return stroke of said bell crank.

4. In a wrapping machine, the combination of a pivotally mounted bell crank, a cam, means actuated by said cam for periodically rocking said bell crank to perform a forward stroke away from a home position followed by a return stroke, a driven member mounted to pivot on the same axis as said bell crank, said driven member being normally movable without obstruction about said pivotal axis through the same are as said bell crank, a compression spring disposed between one arm of said bell crank and said driven member for imparting movement from th bell crank to the driven member during the forward stroke of the bell crank, said spring being disposed so that during the initial stage of the forward stroke of said bell crank the portion of said arm adjoining said spring moves substantially in the axial direction of said spring, connecting means between the spring, said arm and said driven member which permit, in the event of obstruction to movement of said driven member on the forward stroke of the bell crank, movement of said spring from its initial position in relation to said arm and driven member in the direction to bring its line of action progressively nearer a position radial to said pivotal axis, and an adjustable screw on the other arm of said bell crank, said screw constituting an abutment for positively imparting movement from the bell crank to the driven member on the return stroke of said bell crank.

5. In a wrapping machine, the combination with a lifting plunger for lifting articles in succession into a wrapping mechanism of a pivotally mounted driving member comprising an arm projecting from its pivotal axis, a cam arranged to periodically rock said driving member to perform a forward stroke away from a home position followed by a return stroke, a driven member mounted to pivot on the same axis as said driving member and normally free to move without obstruction about said pivotal axis through the same are as said driving member, a linkage connecting said driven member to said lifting plunger, and arranged to raise and lower said lifting plunger in response to rocking movement of said driven member, said riven member comprising an arm projecting from said pivotal axis, a spring disposed between said arms for imparting movement from the driving member to the driven member during the forward stroke of said driving member, said spring being disposed so that during the initial stage of its forward stroke the portion of the arm on said driving member adjoining said spring moves substantially in the axial direction of said spring, connecting means between said spring and said arms which permit, in the event of obstruction to movement of the driven member during the forward stroke of the driving member, movement of the spring from its initial position in relation to said arms in the direction to bring its line of action progressively nearer a position radial to said pivotal axis, and an abutment for positively imparting movement from the driving member to the driven member on the return stroke of said driving member.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 1,569,672 Peabody Jan. 12, 1926 1,733,936 Boughton Oct. 29, 1929 1,833,229 Bent Oct. 18, 1932

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