US2977731A

US2977731A - Wrapping machines

Info

Publication number: US2977731A
Application number: US847633A
Authority: US
Inventors: Brook Leonard; Lazenby Edwin Hall; Wilson Peter Gordon
Original assignee: Forgrove Machinery Co Ltd
Current assignee: Forgrove Machinery Co Ltd
Priority date: 1958-10-21
Filing date: 1959-10-20
Publication date: 1961-04-04
Anticipated expiration: 1978-04-04

Description

WRAPPING MACHINES 4 Sheets-Shee-t 1 Filed Oct. 20, 1959 .N Sw

April 4, 1961 L. BROOK HAL 2,977,731

WRAPPING MACHINES Filed Oct. 20, 1959 4 Sheets-Sheet 2 lnl11 April 4, 1961 L. BROOK ETAL 2,977,731

WRAPPING MACHINES Filed oct. 2o, 1959 4 sheets-sheet s l; Il

LIV

um] 4 M s Maza.,

April 4, 1961 L. BROOK ETAL 2,977,731

wRAPPNG MACHINES Filed-oct. 2o, 1959 4 sheets-sheet 4 theiigures.4

son,-' C ookridge, Leeds, England, assignors to` The i Forgrove Machinery Company Limited, Leeds, England, acompany of GreatBritain r Fried oct. zo, 1959, ser. No. s41,63s

` Claims priority, application Great Britain Oct. 21, 1958 sclaims. (ci. sse-,74)

This invention relates togwrapping` machines Vof the type comprising a continuouslytravelling conveyor for Afeeding a procession of articles'up, to a stop and transfer mechanism driven `in synchronism with the wrapping machine for feeding the articles arrested by the stop to the wrapping machine in^ timed intervals.

succession iand yat regularly Patented Apr. 4, 196,1

by heat sealing and crimping dies which also sever the The invention/provides a wrapping machine of theA `above type which includes a detector for testing the articles faccumulating'in front of the stop, and an electrical control mechanism controlled by the detector for stopping Vor at least slowing down the wrapping machine .v and transfer mechanism when the number of accumulated articles falls below -a given limit and preventing the wrapping machine and transfer mechanismn from running at normal speed until the requiredl accumulation of articles has been restored, ,the circuit including a delay device for, delaying its response to signals from the de- .tector demanding normal speed. t

, TheA electrical control mechanism may be arranged to stop the wrapping machine and transfer mechanism at `.a'predetermined position in their cycle when a gap is `detected in the bank :of articles in front of the stop and 4include a manually operable switch for restarting the wrapping machine and transfer mechanism when said gap has been removed.

The transfer `mechanism ispreferably constituted by t a pocketed infeedconveyor to the wrapping machine and a device driven in synchronism with it for transferring 1n succession to the infeed conveyorthe articles arrested by the stop.

VThe electrical mechanism maybe arranged `to slow `downnthel wrapping machine and transfer mechanism when a :gap is `sensed by the detector in the bank of articles in front of the stop and tocause the wrapping machine and transfer mechanism to revert automatically to normal speed when said gap is removed and a further detector m-ay be. provided in association-with the infeed conveyor for automatically stopping the wrapping' m-achine `and transfer mechanism ,whenever a pocket in the `infeed conveyor is empty. q

Two specific embodiments of the invention will now reference to the accompanying drawings, `in whichz.

fllig. l is a sideV elevation showing the wrapping ma- -ffchine and associated conveyors, t Y

Fig. 2 is a corresponding plan View,

-be described in more detaiL, byl way of example, with Fig. 3 is 'a circuit diagram showing aviirst form of elecf-trical Toont-rol' systemfor the wrapping machine, and ,;.1.Fig. 4 is a circuit di-agram showing an Yalternative form fDfelectrical control system.

Like reference numerals indicate like parts throughout The wrapping machine .is ofthe known type in which tube into individual packages. The wrapping machine is accordingly not illustrated in detail.

The articles 10 to be wrapped are fed to the machine at regularly spaced intervals by the chain lugs 12 of a pocketed infeed conveyor 11. A web 13 of Wrapping .material is drawn from a reel 14 .(or from a reserve reel 15) and folded to form a tube about the advancing articles by a folding box 16, the entubed articles being advanced by upper and lower propelling belts 17, 18 to heat sealing and crimping dies 20 which form the transverse seals in the'tube and 4also sever it into individual packages.

The wrapping lmachine has a main drive shaft 21, which drives the driveV shaft 22 of the infeed conveyor 11 through suitable gearing (not shown) Iand has a fast driving motor 23 and a slow driving motor 24. The fast. motor 23 can drive the shaft 22 through a belt drive 25 andthe slow4 motor 24 can drive the shaft 22 through a beltdrive 26, bevel gearing 27 and la ratchet mechanism 28 which permits, when necessary, the fast motor to 'overdrive the ,slow motor.

The articles 10 are'supphed to the infeed conveyor `1`1 by Va continuously travelling belt 29, driven by a motor I.30 which also drives side conveyor belts 31 which prevent the articles on the belt 29 from slewing. The articles are deposited in batches on the infeed end vof the belt 29 by chutes or other convenient mechanism and the belt feeds the articles up to a stop 32 against which the articles accumulate as shown at the bottom left-hand side of Fig. 2. The articles are transferred `in succession from the belt 29 to the infeed conveyor by an overhead transfer chain 33, driven from the infeed conveyor by a chain 34 and carrying lugs 35 for cngaging the articles Iwhich are forked so that they may embracethe lugs 12 on the infeed conveyor.

A detector is associated with the bank of articles in front of the stop 32 and controls the Wrapping machine in such fashion as to provide an adequate supply of articles to the infeed conveyor 11. This detector may be constituted either by a photo-cell 36 and an associated light source 37 or by a spring loaded trip finger 38 resting on the accumulated bank of articles and an as sociated switch 39.

Figs. 3 and 4 illustrate two alternative electrical control systems which may be utilized under control of the detector to exercise appropriate control of the speed of the wrapping machine.

With the system of Fig. 3, the wrapping machine (and 'thereforethe infeed conveyor and the overhead ight conveyor) Aare automatically stopped whenever the supply of articles tothe stop 32 is inadequate, ibut can be restarted manually when a sufficient bank of articles has again accumulated in front of the stop. 'Ihe machine is stOpped at a predetermined position in its cycle such that the lugs35 Vof the transfer chain are not positioned in the path of an article on the belt 29 when the machine cornes Vto rest. With the system of Fig. 4, the wrapping machine (an-d therefore the infeed conveyor and the overhead flight conveyor) are automatically caused to change from fast to slow speed when the supply of articles to the stop 32 becomes inadequate and to revert to fast speed when the supply of articles becomes adequate again. Provision is alsomade whereby the machine is automatically stopped in the event'of a gap in the procession of articles on the infeed conveyor 11. n l n y y Y' The control Vsystem of Fig. l3will now be explained. AVThe fast and slow motors 23, 24 (Fig. 2)` 'are respectively provided with

contactors

52 and 51 whereby the motors may receive current from lines L1, L2 and L3 when an isolator switch 40 is closed.

In the initial condition, with no infeed of articles to thel stop 32 (Fig. 2) the photocell 36, which receives cur- -`rent from a transformer 41 via a full wave rectifier 42, is

illuminated and therefore conducting. As the resulta relay 2R is energized and its contacts 2R1 are closed.

Consequently another relay 1R is energized and its contacts 1R1 are open. A switch S1 Operated by a cam on the wrapping machine, is connected in parallel with contacts 1R1. In the initial condition the machine cannot be started with the switch S1 open, but if the switch S1 is closed and the slow start button 43 is depressed, the coil 1C of the slow motor contactor is energized, through supply of articles to the stop 32 (Fig. 2). The switches are then in the position shown in Fig. 3, the photo-cell 36 is not conducting, the relay 2R is de-energized, contacts 2R1 are open, the relay 1R is de-energized and the contacts 1R1 are closed. Pressing the slow button 43 now venergizes the slow contactor coil 1C through the circuit already traced. With slow contactor coil 1C energized, contacts 1C1 close and the slow contactor coil 1C .is self-maintained via relay contacts 1R1, overload trip Switch 44, contacts 1C1,.normally closed contacts 2C3, .st'op button 45,

landtrip switches

46, 47. The machine therefore runs at slow speed and will continue to run so long as the infeed is full. Pressing the fast button 48 will now energize the fast contactor coil 2C which is selfmaintained by closure of contacts 2C2, and the machine will now run at fast speed and continue to do so while the infeed is full. The energizing of the fast contactor coil 2C causes contacts 2C3 to open to de-energize the slow contactor coil 1C. If any lgap appears in the bank of articles in front of the stop the photo-cell 36 will be illuminated and energize relay 2R, causing contacts 2R1 to close to energize the relay 1R with the result that the contacts 1R1 will open and the machine will stop at the predetermined time in its cycle at which the cam opens the switch S1.

A capacitor C connected across the relay 1R prevents the relay 1R from becoming de-energized, and so closing the vcontacts 1K1, immediately in response to opening of -the contacts 2R1, and thus constitutes a delay timer which prevents the machine from being started unless the photocell 36 yis darkened for more than a certain length of time. This enables the cell to distinguish between a solid 4bank 'of articles and freely conveyed articles, since the gaps between freely conveyed articles allow light to fall on the cell andthe `darkening of the cell by the passage Iof one article is not of sufficient duration to de-energize y the relay 1R and thus enable the machine to be started.

Thus the passage past the photo-cell of articles with gaps 'between has the same elect as no articles at all.

The circuit includes `a normally open pair of contacts 102, which are closed by energization of theslow contactor coil 1C yand whichso long as they are open prevent vthe-fast contactor coil 2C from being energized by depression of the fast button 48. The machine cannot therefore be started at fast speed and it is necessary first Vftorun it at slow speed.

VThe cycle ofoperation is therefore as follows: With no supply of articles the machine does Vnot run 'as light is reaching the photo-cell 36. The rst articles to arrive.ip ass.the.cell withgaps between themso they do not darken the photo-cell .for long enough for the control cirperniit of -startingofthe machine. Wtien a sufficient 'n'ut'nbetof articles have ylgraclted together against the end stop 32, they cut oli the light to the cell 36 and, after the above-mentioned delay, the machine can be started and takes the'` articles in turn from the end stop. lf the rate of arrival of articles exactly matches the machine speed, the mahinewill run continuously. If the supply of articles reduces or fails, the bank of articles will be used up and light will reach the cell stopping the machine. If the supply has only reduced momentarily the bank will'then be immediately built up again and the machine can be restarted. The machine will therefore adjust itself to the rate of supply of articles and will never run with the pockets of the infeed conveyor empty.

In practice the machine speed is made very slightly faster than the average rate of arrival of the articles.

This ensures that no excessive build up of'articles can occur on the conveyor belt Z9.

Turning now to the system shown in Fig. 4, the circuit includes a trip switch 53 controlled by a feeler 54 bridging a pair of consecutive articles on the infeed conveyor 11. The trip switch 53 remains closed so long'as there is no gap in the procession of articles on the conveyor 11 but immediately the feeler 54 encounters an empty pocket in the conveyor 11 the switch 53 opens. Whenever there is a gap in the bank of articles in Vfront of the stop '32 (Fig. 2) the photo-cell 36 is conducting. As the result a relay 3R is energized to close normally open contacts SR1 and energize relay 2R, so opening contacts 2R1 and closing contacts 2R2. Depression of the start button 48 will, provided the trip switch 53 is closed, complete a. circuit from transformer 55, via stop button 45, and trip switches 47, 53, 44 and 46 to energize relay 1R, to close contacts 1R1 and IRZ. Closure of rcontacts 1R2 completes a holding circuit for the relay 1R and closure 4of contacts 1R1 energizes the slow running contactor coil 1C via contacts 2R2. The machine will accordingly run at slow speed. l

When the photo-cell 36 is darkened by passage past it of an article, it ceases to conduct, relay 3R is deenergized and contacts 3R1 open. If the darkening of the photo-cell continues for a predetermined time, deter- `mined by the capacitor C connected across the relay 2R, the relay 2R will be de-energized. Temporary darkening of the photo-cell will not, however, result in de-energization of the relay 2R. When the relay 2R is de-energized contacts ZRZ open and contacts 2R1 close. The opening of contacts 2R2 de-energizes the slow contactor coil 1C and the closing of contacts 2R1 energizes the fast contactor coil 2C via relay contacts 1R1 and 2R1, with the .result that the machine runs at fast speed.

A gap in the line of articles in the infeed causes the photo-cell 36 to be illuminated whereupon it conducts, energizing relay 3R. As the result, contacts 3R1 close, energizing relay 2R. Contacts 2R1 then open and contacts ZRZ close and the machine immediately reverts to slow speed.

Themachine will not run at fast speed at any time unless the photo-cell remains dark for a period in excess of the release time of the delayed relay 2R, but when running at fast speed it reverts to slow speed immediately whenever the photo-cell is illuminated.

The release time of the relay 2R can be varied by changing the value of the capacitor C.

The closing of the slow only switch 50 energizes relay 2R, causingcontacts 2R1 to be held open and contacts 2R2 to be held closed and the machine can then yrun only at slowv speed irrespective of the infeed condition.

Opening of the tripswitch 53 or depression of the stop Vbutton 48 will stop the machine automatically by deenergizing relay 1R, whether the machine is running at fast or slow speed.

Where the photo-cell 36 and light source 37 arereplac'ed by a switch 39 and trip lfinger 38, the switch will be arranged to close to energize relay 2R in Figs. '3 A'or 4 whenever there is a gap in theline of articles approaching the stop but will be openeti'by the trip'nger 38 to thefast'speed' of the wrapping machine is slightly in excess of the rate of arrival ofthe articles at the stop 32 and the slow speed is less than the rate of arrival. This gives smoother operating conditions. Thus the machine operates on the two speed drive under normal conditions but in the event of a complete failure of the supply of articles the feeler 54 opens thet'rip switch 53 and stops the machine.' The machine must then be restarted by the operator when the supply of articles in the pocketed infeed conveyor and up to the stop 32 has been re-established.

What we claim as our invention and desire to secure by Letters Patent is:

1. A wrapping machine comprising a wrapping mechanism, a continuously travelling band conveyor for supplying articles to a delivery station, a stop at the delivery station for arresting articles on said conveyor to form a bank of articles thereon abutting against said stop, a transfer mechanism for feeding. the articles arrested by said stop from the delivery station to the wrapping mechanism in succession and at regularly timed intervals, motor means connected to drive said wrapping mechanism and said transfer mechanism, a detector for testing the bank of articles accumulated in front of said stop, and an electrical control mechanism for said motor means including speed control means,l which is switchable under control of said detector from a normal condition in which it permits said motor means to run at a normal speed to a speed reducing condition in which it reduces the speed of said motor means, said speed control means being switched to its speed reducing condition when the number of articles in said bank falls below a given limit and being switched back to its normal condition when the number of articles in the bank is again in excess of said limit, and a delay device for delaying return of said speed control means for its speed-reducing to its normal condition.

2. A wrapping machine according to claim l, wherein the detector is constituted by a photo-cell and an associated light source. l

3. A wrapping machine according to claim l, wherein the detector is constituted by a feeler displaceable by the articles approaching the stop and an associated switch.

4. A wrapping machine according to claim l, wherein said transfer mechanism is constituted by a pocketed infeed conveyor for conveying articles in succession to the wrapping mechanism and a device driven in synchronism with said infeed conveyor for transferring in successionl to the pockets thereof articles arrested by said stop.

5. A wrapping machine comprising a wrapping mech anism, a continuously travelling band conveyor for supplying articles to a delivery station, a stop at the delivery station for arresting articles on said conveyor to form a bank of articles thereon abutting against said stop, a pocketed infeed conveyor for conveying articles in succession to the wrapping mechanism, a transfer chain driven in synchronism with the infeed conveyor for transferring in succession to the pockets thereof articles arrested by the stop, said transfer chain including lugs for engaging said articles and transferring them to said in said circuit in parallel with said 'first switch, and' a `cam driven by said motor for openinglsaid secondswitch t at a time in each cycle of operation of said transfer chain lwhen said lugs are clear of said bank of articles.

6; A wrapping machine comprising a wrapping mechanism, a continuously travelling band conveyor for sup plying articles to a delivery station, astop at the delivery station for arresting Athe articles on said conveyor to form a bank of articles thereon abutting against said stop, a pocketed infeed conveyor for conveying articles iny succession to a wrapping mechanism, a transfer chain driven in synchronism with the infeed conveyor for transferring in succession to the pockets thereof articles arrested by the stop, said transfer chain including lugs for engaging said articles and transferring them to said pockets, fast and slow motors connected to drive said wrapping mechanism, said infeed conveyor and said transfer chain at fast and slow speeds respectively, manually operable starting switches associated respectively with said fast and slow motors, a detector for testing the articles accumulated in fron-t of said stop and an electrical control mechanism for said motors including means for prevent ing said fast motor from running in response to operation of its start switch until the slow motor is running, means for stopping the slow motor when 'the fast motor is running, a relay, a rst stopping switch in a circuit supplying energizing current to said motors, means controlled by said detector for actuating vsaid relay to open said first stopping switch when the number of articles in said bank falls below a given limit and to close said tirst stopping switch when the number of articles in said bank is again in excess of said limit, means for delaying closure of said first stopping switch by said relay, a normally closed second stopping switch connected in said circuit in parallel with said first stopping switch, and a cam operated by whichever of said motors is running for opening said sec ond stopping switch at a time in each cycle of operation of said transfer chain when said lugs are clear of said bank of articles.

7. A wrapping machine comprising a wrapping mechanism, a continuously travelling band conveyor for supplying articles to a delivery station, a stop at the delivery station for arresting the articles on said conveyor to form a bank of articles thereon, a transfer mechanism for feeding the articles arrested by said stop from the delivery station to the wrapping mechanism in succession and at regularly timed intervals, fast and slow motors connected to said wrapping mechanism and said transfer mechanism so as to be effective to drive them alternatively at fast and slow speeds respectively, a detector for testing the articles accumulated in front of the stop, and an electrical control mechanism for said motors including speed control means which is switchable from Va fast condition to which it causes said fast motor to run to a slow condition in which it causes said slow motor to. run,

l said speed control means being switched to its slow conpockets, an electric motor connected to drive said wrapping mechanism, said infeed conveyor and said transfer chain, a detector fortesting the articles accumulated in front of said stop and an electrical control mechanism for said motor including a relay, a first switch in a circuit supplying energizing current to said motor, means controlled by said detector for actuating said relay to open said first switch when the number of articles in said bank falls below a given limit and to close said first switch when the number of articles in said bank is again in excess of said limit, means for delaying closure of said first switch Y by said relay, a normally closed second switch connected dition when th-e number of articles in said bank falls below a given limit and being switched back to its fast condition when the number of articles in the bank is again in excess of said limit, and a delay device for delaying return of said speed control means from its slow to its fast condition.

8. A wrapping machine comprising a wrapping mechanism, a continuously travelling bank conveyor for supplying articles to a delivery station, a stop at the delivery station for arresting the articles on said conveyor to form a bank of articles thereon abutting against said stop, a pocketed infeed conveyor for conveying articles in succession to said wrapping mechanism, a transfer device driven in synchronism with said infeed conveyor for transferring in succession to the pocketsthereof articles arrested by said stop, fast and slow motors connectedto said wrapping mechanism, said'infeed conveyor and said transfer device so as to be effective to`drive them alter-r natively at fast and slow speeds respectively, a detector j for testing thegarticles accumulated in front of thestop, `-r'alnfe'lect''rical control mechanism for said'motors including *speed control means which is switchable from' a fast condition in ywhich itcauses said fast motor to run to a slow condition in which it causes said slow motor to run,

said vspeed Icontrol means being switched to its slow condition When the number of articles in said bank falls below a given limit and being switched back to its fast condition when the number of articles in the bank is again in excess of said limit, and a delay device for delaying return of said speed control means from its slow to its ofY articles in the pockets of said infeed conveyor and a VReferences Cited in the file of this lpatent UNITED STATES PATENTS 2,144,448 Brightwell Jan. 17, 1939 2,609,779 Goldsworthy Sept. 9, 1952 2,653,430 Vogt Sept. 29, 1953 2,855,740 Noland et al Oct. 14, 1958 2,934,869 Engleson et al May 3, 1960