EP0242105B1

EP0242105B1 - Transfer mechanism with jam detector

Info

Publication number: EP0242105B1
Application number: EP19870302985
Authority: EP
Inventors: Frank Donald Risko; Thomas Dayton Lewis
Original assignee: Ex-Cell-O Corp
Current assignee: Ex-Cell-O Corp
Priority date: 1986-04-14
Filing date: 1987-04-06
Publication date: 1991-06-26
Also published as: NO871586D0; JPS6331A; EP0242105A3; NO871586L; DE3770975D1; EP0242105A2

Description

This invention relates generally to transfer mechanisms and, more particularly, to such a mechanism including, means for detecting whether or not the product being handled has actually been transferred.
USA-4,566,251 merely lifts by a lifter a part of cartons from a conveyor in a bottom forming section into rails, to be carried through a sterilant atmosphere, and then rotated into an upside-down condition for drying, and then back to an upright condition onto a conveyor in the top filling and forming section. No provisions is made to detect jamming.
The above described machine is but one example of a machine wherein a product, such as a paperboard carton, must be processed through a plurality of internal transfers prior to being filled with a liquid product, in the event of an unsuccessful transfer of a carton at any of the transfer points oncoming cartons will continue to index and feed into the jammed carton. If undetected, there results an increased load on the indexing devices, which may break or damage machine components.
It is apparent that various mechanical or other type means may be used to determine that a transfer has occurred at a particular transfer point.
USA-2,934,869 discloses an article detecting mechanism including a first electric eye device for detecting the presence or non-presence of an article in passing buckets, a transfer mechanism for transferring the articles to cartons in buckets on a carton conveyor, a second electric eye device for detecting the presence or non-presence of an article within the respective cartons, and a mechanical switch for stopping the machine when an empty carton is passing and not when a completely empty bucket is passing. Such detection means are not operative at the transfer location.
A general object of the invention is to enable the detection of a product transfer at a predetermined transfer point.
Another object of the invention is to provide novel electronic means for detecting the transfer of a paperboard carton at a predetermined transfer point in a forming, filling and sealing machine.
A further object of the invention is to provide electronic means coupled with photoelectric and vacuum sensing means for detecting any jam-up of a paperboard carton at a particular transfer point in a packaging machine.
Still another object of the invention is to provide means consisting of a photoelectric sensor, a vacuum sensor, and at least one strobe signal adapted to detect the presence of signals for both sensors.
According to this invention, we propose a transfer mechanism comprising vacuum actuated transfer means arranged to engage and transfer at least one carton from one processing unit to another, photoelectric means arranged to detect the presence of said at least one carton in said one processing unit, at least one vacuum sensor operatively connected to said transfer means for detecting the increase in vacuum once the transfer means has engaged said at least one carton, and strobe means arranged to produce a periodic strobe signal synchronised with the transfer mechanism movements independently of the outputs of said photoelectric means and vacuum sensor(s) which strobe signal, during correct operation of the transfer mechanism, commences concurrently with the vacuum sensor's detection of the increase in vacuum, and ends when the photoelectric means finishes detecting the presence of said at least one carton, the transfer mechanism being responsive to said outputs and to said strobe signal to stop and processing units when said carton is detected by said photoelectric means but proper vacuum is not available, thereby to prevent jamming at the transfer point. Other features of the invention are set forth in the appendant claims.
An embodiment of the invention will now be described by way of example with reference to the accompanying drawings in which:

Figure 1 is a side elevational view of a fragmentary portion of a machine embodying the invention;
Figure 2 is a side elevational view of a second fragmentary portion of the machine embodying the invention and
Figure 3 is a graphic representation or chart of the timing operation of the Figure 2 structure.

Referring now to the drawings in greater detail, Figure 1 illustrates a loading type of transfer point as may be used to transfer bottom sealed cartons 10 two-at-a-time from an indexing conveyor means 12, moving from left to right in Figure 1, to resilient carriers 14 moving at a right angle with respect to the conveyor. In this instance, the carriers each consist of an inverted U-shaped bracket whose side walls are normally urged toward one another until spread slightly to admit and retain a carton 10 therebetween. To arrive at this point, the cartons 10 typically will have been stripped from a mandrel (not shown) and placed on a stationery rail 16 extending laterally from between a pair of parallel endless conveyors 12 mounted around sprockets 18, as more fully shown and explained in U.S. patent no. 4,566,251, issued January 28, 1986.
The transfer of the pair of cartons 10 from the conveyor 12 to the carriers 14 is accomplished by a lifting mechanism 20, having a support platform 22 above which the cartons are positioned as they leave the rail 16. During the dwell period of the indexing cycle of the conveyor, the lifting mechanism 20 extends between the conveyors and raise each two side-by-side cartons vertically upwardly into the spring biased carriers 14.
At this transfer station it is very critical that the carton properly transfer from the conveyors 12 to the carriers 14. Upon successful completion of the transfer, a conveyor 24 associated with the carriers 14 indexes the cartons onto support rails 26 for the start of a further process step, such as the sterilization process. Sensors, represented at 28, are mounted on the support platform 22 and serve to detect an increase in the force necessary to lift the cartons 10 into the carriers 14. This sensor can be a load cell, a strain gauge device, a spring loaded plate and proximity switch, or a similar device that is capable of an instant response to an increase in the force needed to lift the carton. This response or increased force load would be sensed by the control system and immediately stop the conveyor 24 to prevent further jamming of the carton, damage to the machine, and lost downtime. A carton jammed at this point in the machine can be easily removed without major machine problems. Otherwise, a jam in the machine could cause a compromise of the commercial sterility, and complete machine resterilization may be required, which involves a substantial amount of downtime.
Referring now to Figure 2, once a process, such as a sterilization process has been completed, it becomes necessary to transfer the now sterilized cartons 10 back between another pair of parallel endless indexing conveyors 30 mounted around sprockets 32 to be transported through a filling station and a top sealing station prior to discharge. At this unloading transfer point each pair of cartons 10 will have been carried from a direction toward the reader, or out of the paper, to be transferred to the conveyors 30 moving from left to right in Figure 2.
An unloading device 34 serves to raise a pair of vacuum cups 36 upwardly to engage the pair of cartons 10 being held in the carriers 14. The vacuum cups engage the bottoms of the cartons and pull them down onto a stationary rail 38 and into compartments 40 between the conveyors 30 which will be indexed for the further processing of final filling and sealing of the cartons.
A pair of photoelectric sensors 42 will detect the presence of two cartons as the latter move into the unload station. This fact is recorded and stored in the logic system of the machine control unit. The vacuum cups 36 are operatively connected to vacuum sensors 44, which serve to detect the increase in vacuum after the unloading device has raised the cups 36 to grip the bottoms of the cartons. This event is also noted in the machine control unit, and as the unloading device 34 is cycled and the two cartons are pulled into the conveyor compartments 40, a comparison is made of the signals to determine if cartons that were sensed in the carriers 14 had successfully passed by the photoelectric sensors 42, and had been subjected to sufficient vacuum, as sensed by the vacuum sensors 44, to be pulled into receiving compartments 40. If both signals are not correct within a predetermined time period, the machine control system will be caused to stop, thereby preventing jamming of the cartons at this transfer station.
Figure 3 shows the logic and timing of the photoelectric sensor 42 (PES) and the vacuum sensor 44 (VS), a first strobe signal that is used to define the time duration during which both signals should be present, and a second strobe signal that is used to define the time duration during which only the PES signal should be present. A number of conditions will cause the machine to be stopped:

1. If the PES signal a or b for either carton 10 is lost after being detected prior to the beginning of the first strobe signal c, the machine will be stopped.
2. If the PES signal a or b is lost for either carton 10 after being detected prior to the end of the first strobe signal c, the machine will be stopped.
3. If the PES signal a or b is detected and no VS signal d or e is detected for either carton 10, the machine will be stopped.
4. If the PES signal a or b is detected and the VS signal d or e is lost for either carton 10 prior to the end of the first strobe signal c, the machine will be stopped.
5. If no PES signal a or b is detected, the VS signal d or e will be ignored and the machine will not be stopped.

The strobe signals are unrelated to the PES or the VS signals, and are developed from other timing signals in the machine and synchronized to the conveyor movements. The second strobe signal f is optional and may be used either to back up the action of the first strobe signal c, or in lieu thereof. This second strobe signal f serves to detect that the PES signals a and b have shown that both cartons 10 have been removed, i.e., moved completely past the photoelectric sensors 42 and, hence, have been deposited in the compartments 40 of the conveyors 30. Should any one carton not pass by the photoelectric unit, the pulse would continue as represented by the dash lines in Figure 3.
It should be apparent that the invention provides a novel and efficient means for assuring that transfers of a product, such as paperboard cartons, have occurred at the inlet and outlet of crucial processing operations, such as a sterilization chamber, wherein jam-ups would cause substantial downtime, not only in unjamming and possible machine damage, but in complete resterilization time before the machine can be restarted.

Claims

1. A transfer mechanism comprising vacuum actuated transfer means (34) arranged to engage and transfer at least one carton (10) from one processing unit to another, photoelectric means (42) arranged to detect the presence of said at least one carton in said one processing unit, at least one vacuum sensor (44) operatively connected to said transfer means (34) for detecting the increase in vacuum once the transfer means has engaged said at least one carton, and strobe means arranged to produce a periodic strobe signal (c) synchronised with the transfer mechanism movements independently of the outputs of said photoelectric means (42) and vacuum sensor(s) (44) which strobe signal, during correct operation of the transfer mechanism, commences concurrently with the vacuum sensor's detection of the increase in vacuum, and ends when the photoelectric means finishes detecting the presence of said at least one carton, the transfer mechanism being responsive to said outputs and to said strobe signal to stop said processing units when said carton is detected by said photoelectric means but proper vacuum is not available, thereby to prevent jamming at the transfer point.

2. A transfer mechanism according to claim 1, wherein it is detected whether either of the cooperating photoelectric and vacuum sensing signals (a, d) is detected and then lost or is not detected prior to the end of the strobe signal (b), to thereby stop the processing units should either occur.

3. A transfer mechanism according to claim 1, wherein the strobe signal (b) and the photoelectric signals (a, d) are processed to determine whether said at least one carton (100 has been removed from said one processing unit and deposited in the other.

4. A transfer mechanism according to claim 2, comprising means for generating a second strobe signal (f) wherein said first-mentioned and second strobe signals (c, f) are utilised to detect whether the output (a, b) of the photoelectric means (42) has shown that at least one carton (10) has been removed from said one processing unit and deposited in the other.

5. A transfer mechanism according to any preceding claim adapted to transfer two side-by-side cartons (10) together and to detect jamming of either carton.