GB2129754A

GB2129754A - Feeding apparatus and the method

Info

Publication number: GB2129754A
Application number: GB08327460A
Authority: GB
Inventors: David Charles Morton
Original assignee: Baker Perkins Ltd
Current assignee: Baker Perkins Ltd
Priority date: 1982-11-05
Filing date: 1983-10-13
Publication date: 1984-05-23
Also published as: GB8327460D0

Abstract

A succession of product items (11) are delivered from a procession in end-to-end abutment in feeding apparatus (12) to a faster moving input conveyor (13) of a wrapping machine, in phase with the movement of the flights (14) of an infeed conveyor (10) of the wrapping machine by sensing (26) the position of a leading edge of an item about to be transferred to the input conveyor and comparing (25) it with the in-phase position. The delivery conveyor (12) is set to under-feed relative to the wrapping machine rate and a servo (22)-actuated differential (21) raises the speed of the delivery conveyor to an over speed-relative to the wrapping machine on a signal from the comparing means (25), whenever the leading edge is rearward of an acceptable range of positions, to restore the in-phase transfer of items. <IMAGE>

Description

SPECIFICATION Feeding apparatus and method This invention relates to feeding apparatus and a feeding method concerned with the delivering of articles being conveyed in a line to, and in line with, a machine infeed. More particularly the invention is concerned with a method of and apparatus for delivering a succession of articles from a procession in end-to-end abutment in the feeding apparatus to a faster moving input conveyor of a machine which performs at a machine rate to operate in a cycle on each said article, said delivery being such that transfer of successive articles from the feeding apparatus to the machine is in phase with the cyclic operation of the machine. The invention has particular application fo delivery of articles to a wrapping machine.

Chocolate bar wrapping machines operate at high speed and require a uniform delivery of bars to an infeed conveyor thereof. The source flow of bars for such equipment is continuous but not of reliably constant rate.

It is usual practice to employ as feeding apparatus a metering band carrying a procession of bars which are generally in end-to-end abutment and advancing at a rate corresponding to the cycling rate of the wrapping machine. It is also usual for the procession of bars to extend upstream in a column from a control surface which contacts the bar at the head of the column. The column extends over the whole length of the metering band and onto a faster moving monitoring band upstream of it.

The speed of the wrapping machine is varied to take account of changes in the length of the column caused by fluctuations in supply of bars. In the case of single line feeding, and speeds in excess of 200 bars per minute, a large number of bars in end-toend alignment must be maintained in the column since, otherwise, the required sensitivity of monitoring of changes in column length, and the required speed of adjustment of wrapping machine speed, is too high to be achieved practicably.

Using a control surface at the head of the column to restrain from over-advancement not only the bar at the head ofthe column but also a plurality of upstream bars with which it is an end-to-end abutment can cause damage and vertical displacement of the bars at and near the head of the column.

Published British Patent Application No. 2072124A in the name of the assignee of the present inventor illustrates the use of a control surface.

Published British Patent Applicant No. 2001 029A describes one way of relieving pressure from a long column of articles on a control surface. The head of the column is carried on a short, relatively fastmoving conveyor and the rest of the length of the column on a relatively slower moving column, so that temporary gaps arise between successive product items in their transfer from the slow to the fast conveyor. The size of the gaps is monitored and the speed of the slow belt is switched between two values to maintain the size of the gaps as desired.

The only relationship between the switching and the wrapping cycle is a random one. The size of the gap varies with fluctuations in the size of the bars and with random changes in the traction between the bars and the belts on which they travel. This places limits on the responsiveness of the feeding apparatus to the needs of the machine downstream from it.

US Patent Specification No 4197935 describes a proposal to drive a feed conveyor intermittently, at moments when successive flights of a flighted infeed conveyor are disposed to accept a product item, the conveyor being braked to a standstill at all times other than when it is in one of its intermittent periods of movement. This proposal is consequently limited to relatively slow handling rates, limited to around 200 or so product items per minute, much less than the range of handling rates contemplated in the present proposal.

It is an object of the present invention to avoid or at least mitigate the aforementioned prior art disadvantages.

According to a first aspect of the present invention the delivery method comprises the steps of transporting the article to a downstream end of the feeding apparatus in a continuously moving procession at a basic speed effective to transfer the articles to the machine at a basic rate, which differs from the machine rate by not more than that which is necessary for ensuring that the basic rate remains throughout variation of the conditions of operation of the machine displaced in a constant direction from the machine rate, that is to say, always lower (or higher as the case may be) than the machine rate; sensing an instantaneous position of an article in the procession and providing a signal indicative of the position of a transfer article furthest downstream in the feeding apparatus; and shifting the basic rate temporarily to a modified feeding rate disposed relative to the machine rate in the other direction to the basic rate when necessary in order to secure that the said transfer of successive articles is in phase with the machine cycle.

According to the second aspect of the present invention there is provided delivery apparatus for performing the method of the invention.

Preferably, sensing is carried out on a leading edge of successive product items as they transfer to the input conveyor, the locus of movement of the items including a discontinuity at a point of transfer which is large enough to ensure that a portion of a transferred item forward of its trailing edge cannot be mistaken on sensing for a portion of a product item about to be transferred rearward of its feeding edge.

The discontinuity can be provided by arranging for the items to move to a lower level in transfer so that they are thereafter located at too low a level to be sensed.

Embodiments of the present invention will now be described, by way of example, with reference to the accompanying drawing.

In the drawing: Figure 1 is a perspective view of a first embodiment of feeding apparatus; Figure 2 is a perspective view of a second embodiment of feeding apparatus; Figure 3 is a view from one side of certain components of the first embodiment of feeding apparatus, being a preferred arrangement of the Figure 1 embodiment; and Figure 4 is a like view from one side of an alternative arrangement of the components, also a preferred arrangement of the Figure 1 embodiment.

Referring to Figure 1, a flighted conveyor 10 running at a speed of about 1.7 V is an infeed to a chocolate bar wrapping machine (not shown) Chocolate bars 11 are metered from a metering band 12 onto an input conveyor provided as twin accelerator bands 13 and thence onto the infeed conveyor 10 in timed relationship with the individual flights 14 of the conveyor 10.

A column of chocolate bars in continuous end-toend abutment extends upstream from a discharge end 15 of the metering band (which constitutes the downstream end of the feeding apparatus), past the upstream end 16 of the band and on to a monitoring band 17. The metering band advances at a speed V and the monitoring band at a speed 1.3 Vso that those bars at the back of the column i.e. on the monitoring band are being urged against the bars in the front part of the column i.e. on the metering band. The length of the metering band and the coefficient of friction between it and the bars are so chosen that there is no or substantially no forward slippage of the bars 11 on the metering band 12.

The rate at which the machine wraps is N bars/ min. The average length of each bar is L cms. Speed V is normally set at LN cms/min. The speed of the monitoring band is 1.3 V, of the metering band is V, and of the accelerating bands is 1.5 V, and all these conveyors are driven by the wrapping machine from a shaft 20. The speed of the flighted conveyor 10 is approximately 1.7 V.

Conventional monitoring devices 18 provide sufficient information as to the length of the column of bars that the speed of the wrapping machine can be adjusted to cater for fluctuations in the supply of bars to the monitoring band 17.

Successive bars 11 are transferred, from the metering band 12to the accelerator bands 13, and this can be said to be in phase with the cyclic operation of the wrapping machine when one bar 11 is received and carried forward by each one of the flights 14. Thus, there is a small but significant range of positions in which the transfer bar 27 can be located for any given approach position of the flight 14 which will receive it, where the bar will be collected smoothly. Outside this range, the bar will not be smoothly received by the flight and the bar feed can be said to be 'out of phase' with the wrapping machine. Keeping the feeding apparatus in phase with the wrapping machine is accom plished as follows.

A drive shaft 19 of the metering band 12 is connected to the shaft 20 which is running at the speed of the wrapping machine, through a differen tial mechanism 21. A servo motor 22 is actuable to adjust the setting of the differential. It is only when the servo motor is turning that there is a difference between the velocity of the input shaft 23 and the velocity of the output shaft 24 of the differential.

Actuation of the differential 21 results in a phase adjustment by a shift of the normal basic feeding speed of the band 12, relative to the operational speed of the wrapping machine, to the modified feeding speed.

A shaft encoder 25 which includes logic circuitry is driven by the drive means in order to maintain a timed relationship between the flights of the wrapping machine infeed 10 and the position of the bar 27 at the head of the column on the metering band.

Thus, at a specific point in the wrapping machine cycle, identified by means of a conventional inductive probe and cam (not shown) mounted on the shaft 20, the encoder 25 commences to count a predetermined number of pulses. The duration of the counting period is chosen so that at the end of the programmed count the leading edge of the bar 27, if it is exactly positioned, lies in a line with the sensor 26 (a) and it associated light beam generator 26 (b). The sensor 26 (a) produces an output, which will cause the servo motor 22 to operate, only if light from the generator 26 (b) is incident upon it, i.e.

there is no obstruction between the sensor generator 26 (b) and the receiver 26 (a), when the count programme is terminated.

The servo motor 22 operates the differential for a portion of the wrapping machine cycle time as determined by the programme of the logic circuitry to advance the metering band a small increment in excess of its normal velocity V.

If the sensor 26 (a) sees no light at the end of the programmed count, the metering band continues to run at its normal velocity V and the counting cycle re-commences at the appropriate time in the wrapping machine cycle and continues the sequence until the sensor sees light. The speed V of the metering band is nominallythat ofthewrapping machine, but it is in fact set to "underfeed" i.e. to be reliably very slightly slower so that it will regularly and reliably happen that the differential 21 is actuated to advance the phase of the metering band forward relative to the wrapping machine cycle by a small amount.

Otherwise, if the metering band were set to advance at a speed the same or in excess of that of the wrapping machine, it would be necessary to provide means for sensing over-advancement of articles on the metering band and for actuating the differential to adjust the phase of the metering band rearward relative to the wrapping machine. It will be obvious that, prior to any wrapping taking place, the bar 27 at the head of the metering band has to be arranged to coincide with the end of the programmed pulse count, and the wrapping machine flights have to be so positioned as to accept the barforonward conveying.

In the embodiment of Figure 2, the twin accelerator bands 13 of Figure 1, are replaced by an upwardly inclined input band 30, moving at 1.1 V, and a control finger 31, but other components are as shown in Figure 1, and so bear the same reference numerals. A description of the operation of the control finger is to be found in our published British Patent Application No. 2072124A.

The shaft encoder 25 functions as before but in this case its phasing correction ensures that articles are transferred to the input band 30 within a controlled positional margin of error related to a fixed instance in the cycle of the wrapping mchine and hence the metering band. Since the input band 30 is moving at 1.1 V a gap is permanently maintained between the article 27 at the delivery end of the metering band and the article 28 at the input end of the conveyor 30.Final repositioning and the precise release timing of each article into the wrapping machine flight conveyor 10 is made by the control finger 31 as described in published British Patent Application No. 2072124A and, in order to avoid violent contact of the article by the flight bar 14, the article, once it leaves the control finger 31, is conveyed by twin accelerator bands 32 at a speed greater than the input speed but slightly less than the speed of the flighted conveyor 10. Since the inclined input conveyor 30 carries only a few articles, and these are separated from the column on the metering band 12, the end-to-end pressure against the control finger is very small thereby eliminating any possible damage and vertical displacement of articles.

As mentioned above, the principle of underfeeding is employed in the illustrated embodiments.

Each successive bar released from the metering band 12 will be located an incremental amount further upstream than the previous bar with reference to the instant of scanning, (which is a fixed point in the machine cycle), and there is therefore a real possibility that, ultimately, the rear face of the bar just released will mask the beam at the instant of scanning when light should be incident on the sensor.

This situation is made worse by a varying degree of traction between the bars and the synchronising band.

This has the effect of delaying a switch to a corrective over-feed regime untU several cycles later, resulting in a permanent mis-match between feeding rate and wrapping rate.

The modifications of Figures 3 and 4 illustrate how to overcome this difficulty by disengaging the individually released bars from the plane of scanning in that there is a discontinuity, in the locus of the movement of the articles as they pass from the procession to the input conveyor, which is large enough to ensure that a portion of a transferred product item forward of its trailing edge cannot be mistaken for a portion of 3 product item, about to be sensed, rearward of its leading edge. The scanner is arranged to look exclusively for the end of the rowed up supply, the top surface of the released bars being underneath the scanning line and out of its influence. In this way, the progressive upstream movement of bars relatively to the scanning point can have no effect on the scanning process, thus eliminating possible unwanted signals.

Claims

1. A method of delivering a succession of articles from a procession in end-to-end abutment in feeding apparatus to a faster moving input conveyor of a machine which performs at a machine rate to operate in a cycle on each said article, said delivery being such that transfer of successive articles from the feeding apparatus to the machine is in phase with the cyclic operation of the machine, the method comprising the steps of transporting the article to a downstream end of the feeding apparatus in a continuously moving procession at a basic speed effective to transfer the articles to the machine at a basic rate, which differs from the machine rate by not more than that which is necessary for ensuring that the basic rate remains throughout variation of the conditions of operation of the machine displaced in a constant direction from the machine rate, that is to say, always lower (or higher as the case may be) than the machine rate; sensing an instantaneous position of an article in the procession and providing a signal indicative of the position of a transfer article furthest downstream in the feeding apparatus; and shifting the basic rate temporarily to a modified feeding rate disposed relative to the machine rate in the other direction to the basic rate when necessary in order to secure that the said transfer of sucessive articles is in phase with the machine cycle.

2. A method according to claim 1 wherein the sensing step is performed at the downstream end of the procession on a leading edge of each successive product item during its transfer to the input conveyor, and by the step of so disposing the longitudinal axis of the procession and the input conveyor relative to each other that there is in the locus of movement of the items as they pass from the procession to the input conveyor a discontinuity which is large enough to ensure that a portion of a transferred product item forward of its trailing edge cannot be mistaken in the sensing step for a portion of a product item about to be transferred rearward of its leading edge.

3. A method according to claim 2 comprising the step of disposing the axes such as to cause the items to move to a lower level as they transfer to the input conveyor, whereby once transferred they are located at too low a level to be sensed in the sensing step.

4. Feeding apparatus for delivering a succession of articles from a procession in end-to-end abutment in the feeding apparatus to a faster moving conveyor of a machine which performs at a machine rate to operate in a cycle on each said article, said delivery being such that transfer of successive articles from the feeding apparatus to the machine is in phase with the cyclic operation of the machine, the apparatus comprising: means for transporting the articles to a downstream end of the feeding apparatus in a continuously moving procession at a basic speed effective to transfer the articles to the machine at a basic rate, which differs from the machine rate by not more than that which is necessary for ensuring that the basic rate remains throughout variation of the conditions of operation of the machine displaced in a constant direction from the machine rate, that is to say, always lower (or higher as the case may be) than the machine rate; means for sensing an instantaneous position of an article in the procession and providing a signal indicative of the position of a transfer article furthest downstream in the feeding apparatus; means for shifting the basic rate temporarily to a modified feeding rate displaced relative to the machine rate in the other direction to the basic rate; and means for determining from said signal whether actuation of the shifting means is required in orderto secure that the said transfer of successive articles is in phase with the machine cycle and for actuating the shifting means as required.

5. Apparatus as claimed in claim 4 wherein said means for sensing a position and providing a signal is a photo-electric cell located at the downstream end of the transporting means to sense the position of the said furthest downstream transfer article.

6. Apparatus as claimed in claim 4 or 5 wherein the means for shifting the basic rate is a servo motor coupled to a differential through which the transporting means is driven from the machine such that actuation of the servo motor introduces a differential between the input speed and the output speed of the differential.

7. Apparatus as claimed in claim 4,5 or 6 wherein said determining means is a shaft encoder and associated logic circuits which examines whether signals from the sensing means occur fully in phase with the machine cycle and actuates the shifting means only if they are not.

8. Apparatus as claimed in any one of claims 4 to 7 wherein the apparatus is in combination with an input conveyor of said machine and the determining means is operatively connected to the machine.

9. Apparatus as claimed in claim 8 wherein the sensing means is located at the downstream end of the procession for sensing a leading edge of each successive product item during its transfer to the input conveyor, and in that the longitudinal axis of the procession and the input conveyor are so disposed relative to each other that there is in the locus of movement of the items as they pass from the procession to the input conveyor a discontinuity which is large enough to ensure that a portion of a transferred product item forward of its trailing edge cannot be mistaken by the sensing means for a portion of a product item about to be transported rearward of its leading edge.

10. Apparatus as claimed in claim 9 characterised in that the discontinuity is such as to cause the items to move to a lower level as they transfer to the input conveyor, whereby once transferred they are located at too low a level to be sensed by the sensing means.

11. A method of delivering a succession of articles to an input conveyor, substantially as hereinbefore described with reference to the accompanying drawings.

12. Apparatus for delivering a succession of articles to an input conveyor, substantially as herein before described with reference to the acompanying drawings.