The present disclosure relates to packaging machines, and more particularly to methods and systems for supplying a web of packaging material to indexing-motion packaging machines.
U.S. Pat. Nos. 5,170,611 and 5,205,110, the disclosures of which are incorporated herein by reference, disclose indexing motion apparatuses and methods for vacuum packaging of articles such as hot dogs, sliced luncheon meat, cheese or pharmaceuticals. In one example, an apparatus and method for supplying web material to an indexing advancement mechanism, such as may be associated with a packaging machine which forms the web into a component of a package is disclosed. The web is supplied from a supply roll to an unwind mechanism, which continuously unwinds the web during indexing advancement of the web by the advancement mechanism of the packaging machine. The unwind mechanism includes an unwind motor which is operable to vary the rate at which the web is unwound from the supply roll. Tension is maintained in the web upstream of the advancement mechanism by a take-up mechanism interposed between the unwind mechanism and the advancement mechanism. The unwind motor speed is controlled by the position of a movable arm associated with the take-up mechanism.
U.S. patent application Ser. Nos. 12/605,101 and 12/605,171, filed Nov. 18, 2010, the disclosures of which are incorporated herein by reference, disclose packaging machines including a web transport conveyor transporting a web of flexible packaging material from upstream to downstream locations through a series of stations, and packaging apparatuses including a forming station and a closing station, each having movable die members that are counterbalanced.
This summary is provided to introduce a selection of concepts that are further described below in the detailed description. This summary is not intended to identify key or essential features of the claimed subject matter, nor is it intended to be used as an aide in limiting the scope of the claimed subject matter.
In some examples, systems for supplying a web of packaging material to a packaging machine are provided. A motor rotates a roll of a web of packaging material. A conveyor conveys the web from upstream to downstream. A dancer is located downstream of the roll and upstream of the conveyor. The dancer is movable between first and second positions based upon a change in tension of the web. A control circuit controls the motor and is in communication with at least one sensor sensing the position of the dancer. The control circuit controls the motor to rotate the roll to thereby cause the dancer to move from the first position to the second position. The control circuit calculates a starting speed of the motor based upon the movement of the dancer from the first position to the second position. The control circuit further controls the motor at the calculated starting speed to begin supplying the web to the conveyor.
In other examples, methods for supplying a web of packaging material to a packaging machine are provided. In some examples, the methods include (1) supplying a web of packaging material from a roll to a conveyor that conveys the web from upstream to downstream; (2) providing a dancer located downstream of the roll and upstream of the conveyor, the dancer being movable between first and second positions based upon a change in tension of the web; (3) controlling the motor to rotate the roll and thereby cause the dancer to move from the first position to the second position; (4) sensing the movement of the dancer; (5) calculating the starting speed of the motor based upon the movement of the dancer from the first position to the second position; and (6) controlling the motor at the calculated starting speed to supply the web to the conveyor.
Other examples are described herein below.
Embodiments of systems and methods for supplying a web of packaging material to an indexing motion packaging machine are described with reference to the following figures. The same numbers are used throughout the figures to reference like features and components.
In the present description, certain terms have been used for brevity, clearness and understanding. No unnecessary limitations are to be inferred therefrom beyond the requirement of the prior art because such terms are used for descriptive purposes only and are intended to be broadly construed. The different assemblies described herein may be used alone or in combination with other assemblies. Various equivalents, alternatives, and modifications are possible within the scope of the appended claims.
The support frame 30 is located downstream of the roll 16 and upstream of the noted conveyor. The support frame 30 supports one or more idler rollers 34 for guiding the path of travel of the web 12 from the roll 16 to the noted conveyor. The support frame 30 also supports a dancer 36, which in this example includes a pair of arms 38 and a cross shaft 40. The dancer 36 is movable between a first, raised position shown in
Referring to
The system 10 also includes a control circuit 54 for controlling the motor 14. The type of control circuit 54 can vary and includes a microprocessor having memory and programmable logic for carrying out one or more software routines. The control circuit 54 also has inputs and outputs for receiving and sending information to components of the system 10, such as for example the motor 14 and/or sensors associated with the motor 14 and/or rotary shaft 20 for identifying an angle of rotation made by the motor 14. Further, the control circuit 54 is in communication with one or more position sensors 56,
The present inventors have found it desirable to prevent stretching and/or wrinkling of the web packaging material 12 at startup of the noted conveyor. Previously, especially in situations where jumbo film rolls are used, only heavy or thick webs, such as semi-rigid or rigid webs, could be used. This is due to the fact that if the heavy roll 16 must be unwound by pulling on the web 12 in the direction of arrow 50, lighter web materials would be stretched by the tension required to make the roll 16 turn. Stretching of the web results in the web becoming narrower and creates wrinkles in the web, which are not desirable for packaging. The smaller the diameter of roll 16, the faster the initial speed of rotation that is required to avoid damaging the web 12. The larger the diameter of the roll 16, the slower the initial speed of rotation that is required.
To solve this problem, the present inventors developed a system that includes the control circuit 54, which is programmed to control the motor 14 at start-up to rotate the roll 16 backwards to increase the tension in the web 12 and thereby cause the dancer 36 to move from the second, lowered position shown in
First determine how fast to feed film in inches per seconds
S=index length/(60/cycles per minute)
Second calculate roll diameter
D=R2
R=12 inches/(2 mA/360)
12 inches=the amount of film to achieve the initial movement of the dancer arm 34 from the second position to the first position
π=3.141592
A=degree of rotation of the motor 14 that was required to achieve the initial movement of the dancer arm 34 from the second position to the first position
Third Calculate circumference of roll
C=Dπ
D=diameter
π=3.141592
Fourth calculate motor 14 speed in degree per sec
M=S/(C/360)
After startup, the control circuit 54 can be configured to control the speed of the motor 14 to maintain a substantially constant tension in the web 12 during indexing motion of the noted conveyor. Upon an indexing motion of the conveyor, the control circuit 54 can monitor a time of movement of the dancer 36 from the first position to the second position based upon inputs from the position sensors 56. Thereafter, the control circuit 54 can be programmed to control the speed of the motor 14 to maintain a substantially constant time of movement of the dancer 36 at each subsequent index. Generally, this will require the control circuit 54 to slowly increase the speed of rotation of the motor 14 to accommodate for decreasing diameter of the roll 16 as the web 12 is discharged to the conveyor.
Although only a few example embodiments have been described in detail above, those skilled in the art will readily appreciate that many modifications are possible in the example embodiments without materially departing from this invention. Accordingly, all such modifications are intended to be included within the scope of this disclosure as defined in the following claims. In the claims, means-plus-function clauses are intended to cover the structures described herein as performing the recited function and not only structural equivalents, but also equivalent structures. Thus, although a nail and a screw may not be structural equivalents in that a nail employs a cylindrical surface to secure wooden parts together, whereas a screw employs a helical surface, in the environment of fastening wooden parts, a nail and a screw may be equivalent structures. It is the express intention of the applicant not to invoke 35 U.S.C. §112, paragraph 6 for any limitations of any of the claims herein, except for those in which the claim expressly uses the words “means for” together with an associated function.
The present application relates to and claims priority to and the benefit of U.S. Provisional Patent Application No. 61/476,644, filed Apr. 18, 2011, the disclosure of which is hereby incorporated herein by reference.
Number | Date | Country | |
---|---|---|---|
61476644 | Apr 2011 | US |