This application relates generally to wrapping machines used for wrapping food items and, more specifically, to a wrapping machine with an associated self-calibration process.
Packaging machines are frequently used to automatically wrap film about products, such as trayed food items. The packaging machines typically include a film gripper that grips and pulls the film from a roll of film, side clamps that grip the film, and folders that fold the film underneath the product. Various control systems and sensors may be employed, for example, to control operation of the gripper and to sense product location. It is generally desirable to know the length of the product tray so that wrap parameters will properly accommodate the particular tray size.
In the past, in order to calibrate a machine infeed so as to enable proper determination of tray size being used, a service technician had to place a tray on the infeed station and manually enter tray size information for the tray being used on the machine interface. The package wrapping machine could then calibrate the infeed length of the machine for the purpose of the calibration. This methodology enabled errors to be introduced if the technician fails to input accurate tray size information during the calibration.
It would be desirable to provide an automated wrapping machine with a calibration methodology that does not require the use of a tray and/or that does not require user input of a tray size or dimension.
In one aspect, a wrapping machine for wrapping trayed food products includes a wrap station at which trayed food products are wrapped, a film dispensing system for drawing out film at the wrap station and a conveying system for moving trayed food products along a defined path from an input station to the wrap station. The conveying system includes a conveyor for moving trayed food products from the input station to a trayed item detection arrangement, and a prime mover operatively connected for moving the conveyor. A controller is operatively connected to the trayed item detection arrangement and the prime mover. The controller is configured for carrying out a self-calibration operation in which: the prime mover is operated to cause movement of a portion of the conveyor from a start position to the trayed item detection arrangement; an amount of movement of the prime mover is monitored as the portion travels from the start position to the trayed item detection arrangement and the amount of movement is used to determine a distance from the start position to the trayed item detection arrangement; and the determined distance is stored as a calibration value in memory of the controller for future use during trayed food product wrapping operations.
In another aspect, a wrapping machine for wrapping trayed items includes a wrap station at which film is wrapped around trayed items, and a conveying system for moving trayed items along a defined path from an input station to the wrap station. The conveying system includes a conveyor for moving trayed items from the input station to a trayed item detection arrangement, and a prime mover operatively connected for moving the conveyor. A controller is operatively connected to the trayed item detection arrangement and the prime mover. The controller is configured for selectively carrying out a self-calibration operation in which: the prime mover is operated to cause movement of a portion of the conveyor from a start position to the trayed item detection arrangement; and an amount of movement of the prime mover required for the portion to travel from the start position to the trayed item detection arrangement is monitored and used to store as a calibration value in memory of the controller for future use during trayed item wrapping operations.
In a further aspect, a method is provided for calibrating a package wrapping machine that includes a conveyor for moving trayed items from an infeed station toward a wrap station, and the machine further including a controller for controlling operation of the machine. The method involves the controller: monitoring an indicator of motor rotation of a motor that drives the conveyor as a portion of the conveyor is moved from a first position to a second position; and utilizing the indicator to store a calibration value for future use during trayed item wrapping operations.
The details of one or more embodiments are set forth in the accompanying drawings and the description below. Other features, objects, and advantages will be apparent from the description and drawings, and from the claims.
Referring to
A weighing mechanism 34 is located at the inlet area for weighing the food product as it is placed into the machine. Once a stable weight is determined, the food product 16 is moved laterally into the machine through a light curtain imaging system 38 and past a height sensor array 40 for determining size of the food product and location of the food product on the conveyor. Part of the horizontal conveying system 18A may be shifted (e.g., into or out of the page in
Various motors M are shown and are used primarily for movement of the conveyor components, gripper components and underfolders. However, a plurality of pneumatic components are also provided for control of components, where each pneumatic component is actuatable by delivery of pressurized air.
For the purpose of the above wrap operation, understanding the size of the trayed item being wrapped is helpful to assure proper wrap, as certain wrap parameters, such as length of film pull, can be set based upon the size. For this reason, the machine controller automatically determines tray size each time a tray feeds into the machine, and responsively sets one or more wrap parameters. To enable the machine to accurately determine tray size, a self-calibration operation is carried out by the machine. The self-calibration operation may be carried out as part of machine set-up process and triggered via a user interface of the machine that implements a self-calibration mode, described in further detail below.
Referring now to the schematic side view of
The controller 50 receives inputs from both sensor arrangements 58 and 62, as well as the encoder 54, and is connected to control operation of the motor 52. The controller may also be connected to a user interface 100 (e.g., a touch-screen display) that enables service personnel to select a calibration mode of the machine. In the calibration mode, the controller 50 carries out a calibration operation to determine an infeed length dimension, more particularly the distance X from the position 60 to position 64.
During the calibration operation the prime mover 52 is operated to cause movement of the lug 56 from position 58 to position 64. Movement of the prime mover is monitored based upon output from sensor 54 in order to determine the distance X from the position 60 to the position 64. The determined distance X is then stored as a calibration value in memory of the controller 50 for future use during trayed food product wrapping operations.
In the illustrated embodiment, the portion of the conveyor detected is the push lug 56, but in other embodiments some other part of the conveyor 18A′ could be detected by sensor arrangements 58 and 62. Where the encoder 54 is used to detect rotary movement of the motor 52, the controller 50 counts a number encoder pulses/ticks output by the rotary encoder 54 to move the push lug 56 from the position 60 to the position 64. The controller 50 then determines the distance X by multiplying the counted number of encoder pulses (e.g., A pulses) by a predefined, known distance per pulse (e.g., B mm/pulse). Thus, once the pulse/tick count A is obtained, the distance X is calculated by the controller 50 as:
X=(A pulses) (B mm/pulse)
Notably, the calibration is carried out without conveying any trayed item on the conveyor 18A′ and without requiring a service person to input any tray size information to the user interface 100 of the machine.
By storing the determined distance X in memory, the controller 50 can later use that stored dimension during wrap operations to determine the actual length of a package (trayed item 210) as it is conveyed along the conveyor 18A′. In particular, by counting the number of pulses from when the lug 56 is at position 60 to when the leading edge of a package reaches position 64 as shown in
PL=X−[(C pulses)(B mm/pulse)].
This calculation can be carried out for each trayed item fed into the machine during high speed wrapping operations.
In an alternative implementation, rather than calculate dimension X, the controller 50 may be configured to simply store the pulse count A as the calibration value. In such cases, the controller 50 can calculate package length dimension for each package as:
PL=(A−[(C pulses)(B mm/pulse)].
Referring now to
It is to be clearly understood that the above description is intended by way of illustration and example only, is not intended to be taken by way of limitation, and that other changes and modifications are possible.
Number | Date | Country | |
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62408118 | Oct 2016 | US |