Machine configuration for engaging a cap to a container

Abstract

The controller executes a method (200) for configuring a capping machine to engage a threaded cap with a threaded neck of a container. In the method, angular positions AP are sequentially selected (201) from a predefined set of APs for the cap, each AP corresponding to an orientation of the cap relative to the neck. For each AP, a capping test is performed (100), and the capping machine is operated to engage multiple caps placed at the selected APs with the respective necks of the containers. The capping operations are evaluated for consistent capping performance (202). The method is performed for a sequence of adjacent APs corresponding to a sequence of spatially adjacent cap orientations until consistent capping performance is detected. The capping machine is then configured (204) by setting its operating AP in relation to the sequence of adjacent APs.

Description

[Technical Field]

[0001] The present disclosure relates to the manufacture of packaging containing food products, and more particularly to techniques for configuring capping machines operable to thread a threaded cap onto a threaded neck of a container. [Background technology]

[0002] In the food industry, it is common to package liquid foods in packages made from a paper-based laminate comprising a core layer of paper or paperboard and one or more barrier layers of, for example, plastic.

[0003] One common type of package is produced by forming a sleeve of the paper-based laminate described above, sealing one end of the sleeve to form a neck defining a spout, attaching a cap to the spout, filling the opposite open end of the sleeve with a liquid food product, and sealing the open end to form a final, distributable package. This is just one example. There are many other types of paper-based laminate packages that have a cap attached to a spout.

[0004] The capping machine is configured to rotate the cap so that the threads on the cap tightly mate with the corresponding threads on the neck. An example of such a capping machine is described in International Patent Application Publication No. WO 2016 / 177750.

[0005] Industrial production and packaging of liquid foods is automated, requiring sophisticated process control of machinery to achieve high-volume production. Safe and reliable operation is crucial, as operational failures and resulting production stoppages can have a significant impact on production costs and product quality. For example, it is crucial to avoid operational failures that could damage machinery and result in the waste of mass-produced packaging.

[0006] Capping operations are susceptible to operator error, as incorrect application of the cap to the neck can damage the threads, result in an insufficient seal, or cause leakage. Such packages must be discarded. Incorrect application can also result in problems in downstream production, for example, the need to clean up leaking food at the filling station.

[0007] The aforementioned WO 2016 / 177750 proposes determining the cap start angle to be used when the cap is engaged with the neck and configuring the capping machine to use this start angle during production. This determination is made by performing multiple capping operations at different start angles, searching for the start angle that results in poor capping performance. The capping machine is then configured to use a start angle shifted by 60° from the start angle that results in poor capping performance. The basic rationale is that poor capping performance occurs when the thread end of the cap and the thread end of the neck meet. By shifting the start angle by 60°, assuming that the cap and neck each have three threads and the thread start points are 120° apart, the end of the thread on the cap needs to be positioned midway between the end of the thread on the neck.

[0008] However, it has been found that such blind shifting resulting from poor capping performance may not provide the proper starting angle to avoid incorrect attachment of the cap to the neck during manufacturing. Therefore, alternative techniques for configuring capping machines are needed. Summary of the Invention [Problem to be solved by the invention]

[0009] It is an object to at least partially overcome one or more of the above identified limitations of the prior art.

[0010] One such object is to provide a technique for constructing a capping machine that screws a threaded cap onto a threaded neck of a container.

[0011] Another object is to provide a technique for finding the proper starting angle of the cap relative to the neck to reduce the risk of the cap not being properly attached to the neck.

[0012] One or more of these objects, as well as further objects that may become apparent from the following description, are achieved at least in part by the computer-implemented method of configuring the capping machine described herein, the computer-readable medium, and the control device described herein, the embodiments of which are defined by the dependent claims. [Means for solving the problem]

[0013] A first aspect relates to a computer-implemented method for configuring a capping machine, the method being operable, once configured, to place a cap at a predetermined angular position relative to a neck of a container and rotate the cap relative to the neck to fully engage threads on the cap with corresponding threads on the neck. The method includes sequentially selecting angular positions from a predefined set of cap angular positions until an exit condition is met, the angular positions in the predefined set corresponding to different orientations of the cap's threads relative to the neck's threads; operating the capping machine to perform a plurality of capping operations for each selected angular position, in which each of a plurality of caps is positioned at the selected angular position and rotated to fully engage with a respective neck of each container; and evaluating the plurality of capping operations for consistent capping performance at the selected angular positions. The exit condition requires detecting consistent capping performance for a series of adjacent angular positions corresponding to a series of spatially adjacent orientations of the cap's threads relative to the neck's threads. The method further includes configuring the capping machine by setting the predetermined angular position relative to the series of adjacent angular positions.

[0014] The method of the first aspect actively searches for consistent capping performance within a set of predefined angular positions. The active search terminates when consistent capping performance is detected for a consistent range of cap orientations represented by a series of adjacent angular positions. In other words, the series of adjacent angular positions defines spatially consecutive steps of cap orientation relative to the neck of the container. Compared to prior art, the method of the first aspect significantly reduces the risk of a capping machine outputting a container with an incorrectly attached cap during production. Actively searching for a series of adjacent angular positions with consistent capping performance essentially verifies with a high probability that a consistent range of cap orientations exists that can be used to configure the capping machine. This verification enables the capping machine to be configured to achieve stable, consistent capping performance in production. The method of the first aspect limits waste of containers and caps because the search automatically terminates when a termination condition is met. Therefore, it is not necessary to search for all predefined angular positions.

[0015] As used herein, "liquid food" refers to any food that is non-solid, semi-liquid, or pourable at room temperature, including beverages such as water, fruit juice, wine, beer, soda, etc., dairy products, sauces, oils, cream, custard, soup, paste, etc., or liquid solid foods such as pulses, fruit, tomatoes, stews, etc.

[0016] As used herein, "package" refers to a package or container suitable for containing liquid food products, including, but not limited to, containers formed from cardboard or paper-based laminates, containers made of or containing plastic materials, and the like.

[0017] A second aspect relates to a computer-readable medium comprising program instructions configured, when executed by a processor circuit, to cause the processor circuit to perform the method of the first aspect or any of its embodiments.

[0018] A third aspect relates to a control device configured to perform the method of the first aspect or any of its embodiments, the control device comprising a signal interface for providing control signals for operating the capping machine and for receiving input signals indicative of capping performance.

[0019] Further objects, features, embodiments, aspects and advantages of the present invention will become apparent from the following detailed description and the accompanying schematic drawings. [Brief explanation of the drawings]

[0020] [Figure 1A] 1 is a schematic diagram illustrating a series of processing stations in an exemplary production line for producing packages containing food products. [Figure 1B] FIG. 1B is a schematic diagram of a capping machine in the production line of FIG. 1A. [Figure 2A] 1 is a perspective view of a cap and a container before and after a capping operation. [Figure 2B] 1 is a perspective view of a cap and a container before and after a capping operation. [Figure 3A] 1 is a schematic side view of a portion of a cap having two different angular orientations of the threaded end relative to the threaded end of the container. [Figure 3B] 1 is a schematic side view of a portion of a cap having two different angular orientations of the threaded end relative to the threaded end of the container. [Figure 4] FIG. 10 is a bottom view of an example cap having three equally spaced threaded ends. [Figure 5] 10 is a flowchart illustrating an example of a cap mounting test procedure. [Figure 6] 1 is a graph of measurement data obtained during a capping test procedure. [Figure 7] 10 is a flowchart illustrating an example of a method for configuring a capping machine. [Figure 8] 8 is a graph of an example of the orientation angle of the cap used in the method of FIG. 7. [Figure 9]10 is a flowchart illustrating an example of a method for configuring a capping machine. [Figure 10A] 10 shows an example of the operation of the construction method of FIG. 9 when using the cap orientation angle of FIG. 8 in the context of FIG. 6. [Figure 10B] 10 shows an example of the operation of the construction method of FIG. 9 when using the cap orientation angle of FIG. 8 in the context of FIG. 6. [Figure 11] FIG. 7 shows length thresholds associated with the measurement data of FIG. 6. [Figure 12] 10 is a flowchart illustrating an example of a procedure for determining a length threshold. [Figure 13] 10 is a flowchart of an example of a verification procedure used in the method of FIG. 9. [Figure 14A] FIG. 10 is a diagram illustrating an example of the operation of a verification procedure. [Figure 14B] FIG. 10 is a diagram illustrating an example of the operation of a verification procedure. DETAILED DESCRIPTION OF THE INVENTION

[0021] Embodiments will now be described more fully hereinafter with reference to the accompanying drawings, in which some, but not all, embodiments are shown. Indeed, the subject matter of this disclosure may be embodied in many different forms and should not be construed as limited to the embodiments set forth herein; rather, these embodiments are provided so that this disclosure will satisfy applicable legal requirements.

[0022] Where possible, any of the advantages, features, functions, devices, and / or operational aspects of any of the embodiments described and / or discussed herein may be included in any of the other embodiments described and / or discussed herein, and / or vice versa. Additionally, where possible, terms used in the singular herein are intended to include the plural and / or vice versa, unless expressly stated otherwise. Thus, the terms "a" and / or "an" mean "one or more" or "at least one," while the phrases "at least one" or "one or more" are also used herein. The terms "multiple," "plural," and "plurality" are intended to mean the provision of two or more elements. The term "and / or" includes any and all combinations of one or more of the associated listed elements. Terms such as "first," "second," etc. may be used herein to describe various elements, but these elements should not be limited by these terms. These terms are used merely to distinguish one element from another. For example, a first element could be termed a second element, and, similarly, a second element could be termed a first element, without departing from the scope of the present disclosure.

[0023] Well-known functions or structures may not be described in detail for the sake of brevity and / or clarity. Unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this disclosure belongs.

[0024] Like numbers refer to like elements throughout.

[0025] FIG. 1A shows a schematic diagram of an example of a production line for sealed packages containing liquid food products. The production line includes a series of stations 1-4. Sleeve-forming station 1 is configured to reshape a sheet material into a cylindrical package body ("sleeve"). The sheet material may be made from a paper-based laminate, as described in the Background of the Invention section. Top-forming station 2 is configured to receive the sleeve from station 1 and provide a top portion at one open end of the sleeve to form a container. The top portion includes a threaded neck defining an access opening. The neck is also referred to in the art as a "finish." The access opening may or may not be covered with a membrane (foil). The neck is typically made of a plastic material and may be incorporated into the top portion in various ways. In one embodiment, top-forming station 2 is configured to provide the entire top portion by injection molding, as described, for example, in International Application Publication WO 2007 / 106006. In another embodiment, the sleeve material is folded or otherwise manipulated to engage a pre-formed neck element, as described, for example, in DE 102005048821 and WO 2010 / 085182. After top forming station 2, the container has an open end opposite the end with the top portion. Capping station 3 is configured to receive the container from station 2 and screw a threaded cap onto the threaded neck. Filling station 4 is configured to fill the open end of the container with a liquid food product and seal the open end to form a final package containing the liquid food product. Filling station 4 may also be configured to sterilize the package prior to the filling operation.

[0026] Although not shown in Figure 1, any one of stations 1-4 may be duplicated to operate in parallel to increase production line throughput. Each station 1-4 may include one or more machines for performing the processing operations of that station. It is also contemplated that multiple stations may be implemented by a single machine.

[0027] The structure of each of stations 1-4 will not be described in detail, as many embodiments are available and are well known to those skilled in the art. The present disclosure relates to techniques for constructing capping station or machine 3. Thus, the methods and capping stations described herein can be used with any type of package in which a cap is placed on the package neck, i.e., regardless of how the package body and package neck are manufactured.

[0028] 1B. Capping machine 3 includes a first manipulator 31 configured to receive and hold a container 20 produced, for example, by top forming station 2, and a second manipulator 32 configured to hold and place a threaded cap 10 against a threaded neck on container 20 and rotate cap 10 so that its threads engage threads on the neck. Once cap 10 is rotated to engage the neck, the second manipulator releases cap 10 and the first manipulator releases container 20 for transport, for example, to filling station 4.

[0029] FIG. 1B also includes a controller 40 configured to control the operation of the capping machine 3. The controller 40 may or may not be part of the machine 3. The controller 40 may be implemented in hardware or a combination of software and hardware. In the illustrated example, the controller 40 includes a processor circuit 41, a computer memory 42, and a signal interface 43. The processor circuit 41 may include, for example, one or more of a CPU (“Central Processing Unit”), a DSP (“Digital Signal Processor”), a microprocessor, a microcontroller, an ASIC (“Application-Specific Integrated Circuit”), a combination of discrete analog and / or digital components, or other programmable logic devices such as an FPGA (“Field Programmable Gate Array”). A control program including computer instructions may be stored in the memory 42 and executed by the processor circuit 41 to perform the methods and procedures as described herein. The control program may be provided to the controller 40 on a computer-readable medium, which may be a tangible (non-transitory) product (e.g., a magnetic medium, an optical disk, a read-only memory, a flash memory, etc.) or a propagated signal. The signal interface 43 may be configured according to conventional practices to receive input signals and provide output signals. In the illustrated embodiment, the controller 40 is further connected to a feedback device 44 configured to generate audible and / or visible feedback to an operator of the machine 3. For example, the feedback device 44 may include one or more of a display, an indicator lamp, a speaker, a siren, etc.

[0030] The operation of the manipulators 31, 32 is controlled by control signals C1, C2 from a controller 40 based on input signals S1, S2 from the respective manipulators. The manipulators 31, 32 may be configured in various ways to perform their respective functions, and a detailed description thereof will be omitted. Examples are described in the aforementioned International Patent Applications WO2016 / 177750 and WO2007 / 106006.

[0031] 2A-2B are perspective views of cap 10 before and after a capping operation. In FIG. 2A, cap 10 is spaced apart from neck 21 of container 20. In the illustrated example, neck 21 has a threaded portion 22 consisting of three threads 23. Although not shown in FIG. 2A, cap 20 has three corresponding threads. In FIG. 2B, cap 10 is rotated in the direction of arrow R, engaging its threads with threads 23 on neck 21.

[0032] As noted in the Background of the Invention section, the starting orientation of the cap's threads relative to the neck's threads is known to be important to the outcome of the capping operation. This is further illustrated in FIGS. 3A-3B, which are side views of cap 10 slid onto neck (finish) 21 of container 20 with two different starting orientations. Structures located inside cap 10 are shown in thin lines. As shown, cap 10 defines an internal cavity 11 configured to receive neck 21. Internal cavity 11 has a threaded portion 12 on its peripheral wall. Threaded portion 12 includes one or more threads 13 configured to mate with one or more threads 23 on threaded portion 22 of neck 21. Cap 10 is aligned with neck 21 by having a center / axis of symmetry 10a of cap 10 coincide with a center / axis of symmetry 21a of neck 21.

[0033] Generally, a "thread" is a helical structure wound helically around a cylinder or cone. In the example shown herein, the cap 10 defines one or more internal (female) threads 13, and the neck 21 defines one or more external (male) threads 23. Each thread 13, 23 has an outwardly facing thread end or tip 13a, 23a from which the threads 13, 23 wind into the cap 10 and onto the neck 21, respectively. In the field of liquid food packaging, it is common for the cap 10 and neck 21 to each have three threads to limit the rotation of the cap required to remove it from the package. All examples shown herein assume three threads. However, the present disclosure is applicable to any number (n) of threads, where n≧1.

[0034] 3A, cap 10 is positioned with thread end 13a facing the gap between two thread ends 23a on neck 21. This allows thread tip 13a to slide between thread tips 23a as cap 10 is rotated in direction R, guiding thread 23a along thread 13 until cap 10 is securely engaged with neck 21.

[0035] In FIG. 3B , cap 10 is instead positioned so that thread end 13 a faces thread end 23 a on neck 21. As a result, when cap 10 is rotated in direction R, thread end 13 a may slide to the left of thread end 23 a or to the right of thread end 23 a, as indicated by arrow 15. This cap orientation in FIG. 3B results in capping instability. This instability could result in the cap not properly seating on the neck. For example, the cap may be seated at an angle on the neck. An improperly seated cap could result in an insufficient seal on the container, damage to the neck and / or cap threads, or an easily opened final package. Such final package would need to be discarded. Furthermore, if a leak occurs at filling station 4, the production line would need to be shut down for cleaning, resulting in a costly production downtime.

[0036] The following disclosure relates to a technique for configuring a capping machine 3, specifically, a technique for determining a suitable starting orientation of a cap 10 relative to a neck 21 of a container 20 to achieve consistent capping performance of the capping machine 3 when the production line is operated to produce final packages. This technique is based on the fundamental insight that the search for a suitable starting orientation of the cap should be designed to test capping performance at different test orientations of the cap relative to the neck and to find a set of adjacent test orientations that all result in consistent capping performance. This set of adjacent test orientations defines a range of consistent cap orientations within which the capping machine is likely to operate properly. Therefore, a suitable starting orientation is selected from this range, and the capping machine is configured accordingly. Hereinafter, the cap test orientation is also referred to as the "starting angle" or "angular position," abbreviated as AP.

[0037] FIG. 4 is a bottom view of an exemplary cap 10, looking toward the cavity 11. The cap of FIG. 4 is used to further explain and illustrate the construction technique. The cap 10 has three identical internal threads offset around the circumference of the cap 10. Specifically, as shown in FIG. 4, the thread ends 13a are equidistantly distributed around the circumference of the cap 10. For clarity, the threads are not shown. The angular spacing (angle range) ΔA between adjacent thread ends 13a relative to the central axis 10a of the cap 10 is 120° because of the three threads. Due to the symmetry of the thread ends 13a, one skilled in the art will only need to determine the starting orientation of the cap 10 within ΔA. FIG. 4 indicates a predefined set of test directions within ΔA by the reference character [AP]. Each test direction is represented by a dot and corresponds to the angular position AP of the cap relative to the neck on the container. In the illustrated example, 16 dots are equiangularly distributed within ΔA, resulting in an angular spacing of 7.5° between adjacent dots. In some embodiments described below with reference to Figures 8-10, test directions are divided into two different categories: PAP (open dots) and SAP (solid dots).

[0038] As shown in FIG. 4, the cap 10 includes at least one reference element 14 (one shown) having a known position relative to the threaded end 13a. The reference element 14 is used to allow the capping machine 13 to identify the position of the threaded end 13a on the cap 10. Based on the reference element 14, the capping machine 3 can be operated to position the cap 10 at any selected angular position between the threaded end 13a of the cap 10 and the threaded end 23a on the neck 21 of the container 20. This assumes that the capping machine 3 can be operated to position the container 20 with a known orientation of its threaded end 13a. The reference element 14 may be a three-dimensional structure configured to mate with a corresponding structure on a gripping element of the manipulator 32 (FIG. 1B). For example, the reference element 14 may be a protrusion / indentation of a particular shape that mates with a corresponding indentation / protrusion of a particular shape on the gripping element, thereby allowing the cap to reach a predetermined orientation on the gripping element. In another example, the reference elements 14 are visual markings that are detected by the manipulator 32 and used to position the cap 10 .

[0039] FIG. 5 is a flowchart of a test procedure 100 performed to evaluate the capping performance for a selected test orientation of a cap. Hereinafter, procedure 100 is also referred to as a capping test, or CMT. Procedure 100 may be implemented by a controller 40 (FIG. 1B) that is operated to receive input signals S1 and S2 from the capping machine 3 via a signal interface 43 and to provide control signals C1 and C2 to the capping machine 3. During the CMT, the capping machine is operated to perform multiple capping operations in a selected test orientation and measure the capping performance for each capping operation. The number of capping operations is at least two, typically at least five or ten. Each capping operation consumes one cap and one container. The number of capping operations is a trade-off between obtaining sufficient data for subsequent capping performance evaluation and minimizing the consumption of containers and caps.

[0040] In step 101, the control device 40 waits until the container 20 is in the capping position. For example, in step 101, the control device 40 may wait until the signal S2 (FIG. 1B) confirms that the container 20 is in a predetermined position on the manipulator 31. Alternatively, in step 101, the control device 40 may wait for a preset time.

[0041] In step 102, the capping machine 3 is operated to position the cap 10 in a selected test orientation and rotate the cap 10 to thread it onto the neck 21 of the container 20. The cap 10 is rotated to fully engage the neck 21. Here, "fully engage" means that the cap 10 is rotated until it meets a predefined engagement criterion. In some embodiments, the cap fully engages with the neck when the torque acting on the cap 10, or equivalently the container 20, during the cap rotation exceeds a predefined threshold. The torque may be provided by the instantaneous drive force or drive current of a drive unit in the manipulator 32 (FIG. 1B) or may be obtained from a dedicated torque sensor in the capping machine 3. The signal S1 may be indicative of the torque.

[0042] In step 103, the capping performance of step 102 is measured or otherwise quantified. Thus, step 103 results in one or more parameter values ​​indicative of the capping performance. In the following example, the capping performance is given by the parameter "path length," which is the total rotation of the cap from the selected test orientation until the cap is fully engaged. For example, the path length is given in degrees (°) or any equivalent unit. In the following example, if the cap is not fully engaged when the path length reaches the MLV, the path length is set to a predefined maximum length value (MLV). In the example of FIG. 1B, the path length is given by signal S1, which may be generated by the aforementioned drive unit in manipulator 32 or by a dedicated rotation sensor in the capping machine.

[0043] It should be noted that capping performance may be quantified in other ways in step 103. In one example, capping performance is assessed by computer vision based on digital images or videos of the cap 10 and neck 21 during the capping operation and graded according to a predefined scale. In another example, the cap is rotated in step 102 for a predefined time or until fully engaged, and capping performance is given by the maximum torque achieved during the predefined time.

[0044] In step 105, the controller checks whether all capping operations have been performed. If not, the controller returns to step 101 (step 106) and waits until the next container is in position for capping. If all capping operations have been performed, the CTM 100 ends (step 107).

[0045] As indicated by the dashed line, the CMT 100 may include step 104 for terminating the CMT 100 if the path length during the capping operation is too long. The fast termination of step 104 is further described below with reference to Figures 11-12.

[0046] Figure 6 is a graph of measurement data obtained by the CMT at test directions ("start angles") in 10° increments within an angle range of 0° to 120°. For each angle, the CMT included 10 capping operations. The measurement data is shown in terms of rotational path length (°). The measurement data can be divided into three distinct regions 61, 62, and 63, as indicated by the dotted lines. Note that region 61' is an extra region because a start angle of 0° corresponds to a start angle of 120° (see Figure 4). In region 61, there is a bimodal distribution of path lengths in each test direction, with some capping operations having a path length of approximately 580° and some capping operations having a path length of approximately 700°. Thus, region 61 indicates unstable capping performance. The bimodal distribution in region 61 is likely to occur when the cap's thread end and neck meet, as shown in Figure 3B. Region 62 shows another bimodal distribution of path lengths, with one group of path lengths near or at the maximum length value (MLV), which in this example is 950°. Thus, region 62 also indicates unstable capping performance. In the illustrated example, some capping operations for each test direction in region 62 failed to fully engage the cap with the neck. This can occur when the cap threads "override" the neck threads. It is also believed that the specific shape of the top of the container may promote the occurrence of region 62. For example, if the top is prone to deformation when the cap is tightened onto the neck, such deformation can cause an extension of the path length. Region 63, on the other hand, indicates stable capping performance. In the illustrated example, the starting angle for region 63 is between 10° and 40°.

[0047] From FIG. 6, it is easy to understand why the prior art described in the Prior Art section can fail. If poor capping performance is detected for a start angle in region 61, a 60° shift in the start angle will likely result in region 62. If poor capping performance is detected for a start angle in region 62, a 60° shift in the start angle will likely result in region 61. Applicant has instead developed a fundamentally different approach by actively searching for a series of adjacent angular positions (APs) that result in stable capping performance, i.e., by actively identifying at least a portion of a stable region 63. In the example of FIG. 6, region 63 includes a series of four adjacent APs: 10°, 20°, 30°, and 40°. This series may include at least two adjacent APs, preferably at least three, to increase certainty that a stable region 63 has been found. It should be noted that the search for APs with acceptable performance is conducted among a predefined set of APs (test directions). This set is denoted the "predefined set" and will be designated as [AP] below. Referring to the test results in Figure 6, the number of predefined APs is 12, extending from 0° to 110° at 10° intervals. Preferably, the predefined APs in [AP] span the angular range ΔA (Figure 4) to cover the entire range of relevant test orientations. The predefined APs may or may not be equidistantly distributed within ΔA. An equidistant distribution (equal angular intervals) is considered more efficient in detecting the stability region 63. Each AP corresponds to an orientation of the cap, and "a series of adjacent APs" means that the APs correspond to a sequence of spatially adjacent orientations of the cap. To emphasize the spatial relationship, "adjacent APs" is used synonymously with "spatially adjacent APs" in this specification. In the example of Figure 6, AP=10° and AP=30° are spatially adjacent to AP=20°. It is important to note that the angular positions wrap around at the ends of the angular range, since AP=120° is equivalent to AP=0°. Therefore, in FIG. 6, AP=100° and AP=0° are spatially adjacent to AP=110°.

[0048] FIG. 7 is a flowchart of an example of a configuration method 200 according to some embodiments. Method 200 is executed when the need to configure the capping machine arises, for example, when the capping machine is started or restarted, after service or maintenance, or when a new type of container / cap is processed. Method 200 may be implemented by the control device 40 (FIG. 1B). In step 201, an AP is selected from the predefined set [AP] described above. The APs in [AP] are ordered, and step 201 selects APs according to the ordering. Thus, step 201 involves sequentially selecting APs from [AP]. As described below, step 201 is repeated until a termination condition is met in step 203 (described below). After step 201, method 200 executes CMT 100 with the selected AP, for example, according to FIG. 5. In this manner, CMT 100 provides a parameter value indicative of capping performance for multiple capping operations at the selected AP. In step 202, the capping performance is evaluated for detection of consistent capping performance, abbreviated as CCP. As used herein, "consistent capping performance" means that the variability of the parameter values ​​generated by the CMT 100 is sufficiently low. In the following description, the parameter value is path length, and a CCP is detected when the variability of the path length is less than a variability threshold. The variability may be given by any appropriate metric, including, but not limited to, variance, standard deviation, range, interquartile range, coefficient of variation, sum of absolute deviations, mean absolute deviation, etc. If a CCP cannot be detected in step 202, the method returns to step 201, where the next AP is selected from [AP]. If a CCP is detected in step 202, the method proceeds to step 203, where a termination condition is evaluated. The termination condition requires that a CCP be detected for a series of N spatially adjacent APs, where N≧2. As further described below, the termination condition may include additional criteria. If the termination condition is not met, the method returns to step 201.If the condition is met, the method proceeds to step 204, where the capping machine is configured by setting an operating AP to be used as a starting angle for the caps when the capping machine operates in production. The operating AP is set relative to a sequence of N spatially adjacent APs, typically within the range of APs spanned by the sequence. For example, the operating AP may be set to the mean or median of the APs in the sequence, or to one of the APs in the sequence.

[0049] Note that the order of APs in the predefined set [AP] defines the search order of method 200, and thus the order in which APs are searched for CCP detection. In one example, APs are arranged in a random order within [AP]. In another example, APs are arranged in [AP] to represent successive spatial orientations of the cap. This may be achieved by arranging APs in increasing or decreasing magnitude, e.g., from 0° to 110° in FIG. 6. However, it is also possible to start with a different AP and consider AP wrapping, e.g., 30°, ..., 110°, 0°, ..., 20° in FIG. 6.

[0050] In some embodiments, step 203 may further require that a series of N spatially adjacent APs span a predetermined width (angular sub-range) for the termination condition to be met. This increases the certainty that a stable region (63 in FIG. 6) has actually been detected. The predetermined width may be set in the range of approximately 5% to 50% of the angular range ΔA. In some embodiments, the predetermined width is set in the range of 10% to 40%. The predetermined width is preferably set to be smaller than the expected width of the stable region, which in the example of FIG. 6 is approximately 40°.

[0051] Every CMT performed by method 200 consumes a container and a cap. Therefore, it is desirable to minimize the number of CMTs. This can be achieved by skillfully ordering and using a predefined set of [APs] to achieve a more efficient search for the stability region. In some embodiments, [APs] is defined to include a first subset of primary angular positions (PAPs) and a second subset of secondary angular positions (SAPs) distributed among the PAPs. In the context of FIG. 7, step 201 is performed to sequentially select APs from among the PAPs in the first subset. Once a CCP is detected in step 202, at least one SAP is selected from the second subset, where the selected SAP is spatially adjacent to the selected PAP, and a CMT is performed for each selected SAP. Step 203 terminates the method if a CCP is detected at each selected SAP; otherwise, step 203 returns to step 201 and selects the next PAP from the first subset. This search method is graphically illustrated in FIG. 8, where open dots represent PAPs and filled dots represent SAPs. The dots in Figure 8 correspond to the dots in Figure 4. The first and second subsets are designated [PAP] and [SAP], respectively. In the illustrated example, the APs are evenly spaced within ΔA, and each PAP has two adjacent SAPs (one smaller and one larger). In Figure 8, solid arrows 81-87 indicate the order of the PAPs within [PAP], and dashed arrows with primed (') and double-primed (") numbers indicate the adjacent SAPs associated with each PAP. In the illustrated example, PAP=0° is the first selected AP. If a CCP is detected for PAP=0°, then the respective CMT is performed for SAP=7.5° and / or SAP=112.5°, as indicated by arrows 80' and 80". If no CCP is detected for a SAP, PAP=30° is selected, and so on.

[0052] From the above, we can see that the selection of SAPs is contingent on the detection of CCPs for PAPs. This means that fewer CMTs need to be performed when searching for ΔA to find the stability region. Currently, it is believed that 4 to 12 PAPs are needed in the predefined set to adequately cover ΔA, depending on the capping machine, package, and cap configuration. In the example of equidistant PAPs with ΔA = 120°, this corresponds to a spacing of 10° to 30° between spatially adjacent PAPs. In Figure 8, the spacing between spatially adjacent PAPs is 15°.

[0053] In the example of Figure 8, there is one SAP between each pair of spatially adjacent PAPs, and each PAP has two adjacent SAPs, one on each side. There can also be multiple adjacent SAPs on one or both sides of each PAP. The SAPs may or may not be evenly distributed between the PAPs.

[0054] It may be advantageous to match the distribution of PAPs and SAPs to the termination criteria. For example, if the termination criteria are specified as N = 3, i.e., if a CCP must be detected for three spatially adjacent APs, it may be beneficial to place one SAP between each pair of PAPs, as in Figure 8. If the termination criteria are specified as N = 5, it may be beneficial to have two SAPs between each pair of PAPs. In general, for N > 3, efficient detection of stable regions can be achieved by defining the termination criteria to require not only the detection of a CCP at the PAP, but also at one or more SAPs on either side of the PAP. In the example of Figure 8, this corresponds to detecting a CCP at the open dot and the two solid dots indicated by dashed arrows pointing from the open dot.

[0055] As can be seen from FIG. 8, the PAPs do not need to be strictly ordered by size in [PAP]. The ordering shown in FIG. 8 is intended to further speed up the search for the stability region. According to this ordering, [PAP] comprises a first subsequence of PAPs ordered by size, SS1, and a second subsequence of PAPs ordered by size, SS2, interleaved with the PAPs in SS1, with SS2 following SS1 in [PAP]. As indicated by solid arrows 81-87, this results in ΔA being scanned twice consecutively with different PAPs. In effect, the first scan is skipped every second PAP, and a second scan is performed for the skipped PAP. In a variant, two or more PAPs may be skipped in the first scan. It is currently believed that the "jump" between PAPs in the first scan, given by the spacing of the PAPs in SS1, should be smaller than the width of the expected stability region.

[0056] As further shown in Figure 8, the PAPs of both SS1 and SS2 are ordered in increasing order of magnitude. This means that the first and second scans are performed in the same direction across ΔA. While the underlying reason is not fully understood, this is known to speed up the search for the stable region. This also applies when the PAPs of both SS1 and SS2 are ordered in decreasing order.

[0057] It is important to note that the separation of [PAP] into SS1 and SS2 is an optional feature. Other permutations of [PAP], such as increasing or decreasing magnitude, random permutations, etc., may also achieve satisfactory results.

[0058] FIG. 9 is a flowchart of a configuration method 200′ for implementing the use of PAPs and SAPs described above. Method 200′ may be performed by the control device 40 (FIG. 1B). In step 201A, by analogy with step 201 of FIG. 7, a PAP is selected from [PAP] in the order of its placement. The method then executes the CMT 100 with the selected PAP. In step 202, parameter values ​​measured by the CMT are evaluated to detect a CCP. If a CCP cannot be detected in step 202, the method returns to step 201A, where the next PAP is selected from [PAP]. As shown, step 210 is executed to check whether any PAPs remain in [PAP] and generate an alert (step 211) if all PAPs have been processed. The alert may be generated by activating the feedback device 44 (FIG. 1B). If a CCP is detected in step 202, the method proceeds to step 201B, where an SAP is selected from [SAP]. The selected SAP is spatially adjacent to the most recently selected PAP. The method then executes the CMT 100 at the selected SAP. Step 202 evaluates parameter values ​​measured at the most recent CMT for the detection of a CCP. If a CCP is not detected in step 202, the method returns to step 201A. If a CCP is detected in step 202, the method proceeds to step 203′, where it checks whether a CCP has been detected for a sufficient number N of spatially adjacent APs. Otherwise, step 203′ proceeds to step 201B, where another spatially adjacent SAP is selected from [SAP]. If a CCP has been found for a sufficient number N of neighboring APs, step 203′ proceeds to step 204. In step 204, the capping machine is configured as described above. Step 203′ corresponds to the evaluation of an exit condition. As shown in the figure, method 200′ may include a verification step 400, which is executed after step 203′. If the verification fails, the method returns to step 201A. If the verification is successful, the method proceeds to step 204. Step 400, which also corresponds to the evaluation of the termination condition, is further described below with reference to FIGS.

[0059] The operation of method 200′ is further illustrated in FIG. 10A in conjunction with the measurement data of FIG. 6. Here, PAPs are assumed to be spaced 30° apart and follow the order 0°, 30°, 60°, 90°, 15°, 45°, 75°, and 105° in [PAP]. Each PAP has two adjacent SAPs, shifted by −10° and +10°, respectively. Furthermore, three spatially adjacent APs are required for a CCP (N=3). At PAP=0° (AP1), CMT results in a bimodal distribution of path lengths, resulting in fluctuations exceeding the fluctuation threshold. Therefore, no CCP is detected at PAP=0°. Next, CMT is performed at PAP=30° (AP2), as indicated by the solid arrow. Here, the fluctuations are below the fluctuation threshold, and a CCP is detected. Therefore, CMT is performed at SAP=20° (AP2′). A CCP is also detected here. Since N=3, CMT is also performed at SAP=40° (AP2"). Since CCPs are detected at AP2, AP2', and AP2", a stable region is detected and the operating AP (OAP) is set within the stable region, in this example, at 30° (AP2).

[0060] FIG. 10B illustrates another example of the operation of method 200′ in relation to the measurement data of FIG. 6. Here, the PAPs are assumed to be in the following order in [PAP]: 50°, 80°, 110°, 20°, 65°, 95°, 5°, and 35°, with each PAP having two adjacent SAPs shifted by −10° and +10°, respectively. Also assume that the termination condition requires N=3. As shown, no CCPs are detected at PAP=50° (AP1), PAP=80° (AP2), or PAP=110° (AP3). A CCP is detected at PAP=20° (AP4), and is also detected at SAP=10° (AP4′) and SAP=30° (AP4″). Because CCPs are detected at AP4, AP4′, and AP4″, a stable region is detected, and the OAP is set within the stable region, in this example, at 20° (AP4).

[0061] Returning to FIG. 5, CMT 100 may include a fast termination step 104, which helps further speed up the search for the stable region and reduce container and cap consumption. Step 104 checks whether each path length determined by step 103 for the capping operation exceeds a length threshold TH1. If so, CMT terminates. The rationale for step 104 is that if the selected AP results in an excessive path length, it is not in the stable region. The location of TH1 is illustrated in FIG. 11. Those skilled in the art will understand that the path length for a proper capping operation will inherently vary depending on the cap orientation. This is represented in FIG. 11 as a varying baseline of path length, BL. TH1 should be located significantly above BL and significantly below the maximum length value (MLV) assigned to disengaged caps.

[0062] As an alternative to the fast decision step 104, the evaluation step 202 of the configured method 200, 200′ may apply TH1 when detecting a CCP by requiring that all measured path lengths be less than or equal to TH1. Thus, in one example, a CCP is detected only if the variability of the measured path lengths at the selected AP is less than or equal to the variability threshold and all measured path lengths at the selected AP are less than or equal to the length threshold TH1.

[0063] In some embodiments, TH1 is provided as a predefined value. In other embodiments, TH1 is determined by an initial calibration procedure or operation 300 illustrated in FIG. 12. Procedure 300 may be performed by controller 40 (FIG. 1B). In step 301, an AP is selected from a predefined set [AP]. After step 301, a limited CMT 100 is performed with the selected AP. To limit the consumption of containers and caps, the limited CMT 100 includes fewer capping operations than the CMT 100 performed during methods 200 and 200′. For example, the limited CMT 100 may include one to three capping operations. Steps 301 and 100 are repeated, via step 302, until all APs in [AP] or a predefined subset of [AP] have been selected. Next, in step 303, TH1 is determined based on the path lengths measured for each capping operation during the limited CMT (see step 103 of FIG. 5). Step 303 may be performed in many different ways to identify the location of TH1 between BL and MLV (FIG. 12), for example by histogram analysis.

[0064] Procedure 300 is an implementation of an initial calibration operation that operates a capping machine to perform at least one capping operation at each AP in [AP], or a subset thereof, and a length threshold TH1 is determined based on the path length of the cap during the initial calibration operation.

[0065] FIG. 13 is a flowchart of an example of a verification 400 that may be performed as part of the methods 200 and 200′ illustrated in FIG. 9 . Verification 400 is optional and may be performed to improve the reliability of detecting stable regions. Before describing verification 400, reference is made to FIG. 14A , which is a graph of measured path lengths as a function of AP. When each CMT is performed at AP=20°, AP=30°, and AP=40°, the resulting path length distribution is represented by the solid black rectangles 71. The path length variation is low in each rectangle 71, and stable regions 70 can be identified by methods 200 and 200′. Applicant has discovered that potential instability may exist in capping performance at AP. This means, for example, that if the number of capping operations is low relative to the probability of instability occurring, the instability may not appear in the measured path lengths. 14B, a potential instability is shown at AP=110°, where the solid rectangle 71 represents the measured path length and the open rectangle 71′ represents the path length measured even with an increased number of capping operations. As shown by rectangle 71, the variance in the measured path length is low at each of AP=90°, AP=100°, and AP=110°, so a stable region 70 may be erroneously identified by methods 200, 200′. This problem is avoided by verification 400.

[0066] In the example of FIG. 13 , verification 400 includes step 401 of obtaining the path lengths of a set of APs that result in a CCP, i.e., APs identified as likely to be included in the stable region. For example, the path lengths may be obtained from memory 42 in step 401, assuming that the measured path lengths were stored in memory 42 during CMT 10. In step 402, a variability constraint is obtained, for example, from memory 42. The variability constraint may be predefined and is designated ΔL in FIGS. 14A-14B . The variability constraint ΔL defines the maximum allowable variability or spread of the measured path lengths obtained in step 401. The variability may be given by any suitable metric and may have a predetermined value. In step 403, the measured path lengths are evaluated collectively in relation to the variability constraint. If the variability of the measured path lengths is within the variability constraint, step 404 proceeds to step 405, and the verification is deemed successful. Otherwise, step 404 proceeds to step 406, and the verification is deemed unsuccessful. As shown in Figure 9, the outcome of verification 400 can affect whether the termination condition is met. In Figure 14A, verification 400 is successful and region 70 is considered a stable region. In Figure 14B, verification 400 fails and region 70 is not considered a stable region.

[0067] 14A-14B, the variation constraint ΔL may be set to take into account the known variation in the baseline BL given by the cap and container thread structure. Specifically, ΔL may be set with a margin for the known variation in BL relative to the required number (N) of spatially adjacent APs detected within the stability region.

[0068] The present disclosure is not limited to containers made from a sleeve of sheet material, but is applicable to any container comprising a threaded neck configured to mate with a threaded cap.

Claims

1. A computer implementation method for configuring a capping machine (3), wherein, once configured, the cap (10) is positioned at a predetermined angular position (OAP) relative to a neck (21) on a container (20), and the cap (10) is operable to rotate relative to the neck (21) so that the threaded portion (12) of the cap (10) fully engages with the corresponding threaded portion (22) of the neck (21), and the method is Until the termination condition is met (203), an angular position is sequentially selected from a predefined set of angular positions ([AP]) of the cap (10) (201), the angular positions of the predefined set ([AP]) correspond to different orientations of the threaded portion (12) of the cap (10) relative to the threaded portion (22) of the neck (21), The capping machine (3) is operated (100) to perform a series of capping operations, in which, for each selected angular position, each of the multiple caps (10) is rotated so that it is positioned at the selected angular position and fully engages with each neck (21) on each container (20). To evaluate the consistent capping performance at the selected angular position, the multiple capping operations are evaluated (202). Equipped with, The termination condition requires detecting consistent capping performance for a series of adjacent angular positions corresponding to a series of spatially adjacent orientations of the threaded portion (12) of the cap (10) with respect to the threaded portion (22) of the neck (21), The method further includes configuring the capping machine (3) (204) by setting a predetermined angular position (OAP) in relation to the series of adjacent angular positions. method.

2. The angular positions within the predefined set ([AP]) extend to a predefined angular range (ΔA) corresponding to the angular spacing of one or more threads (12) on the cap (10). The method according to claim 1.

3. The angular positions within the predefined set ([AP]) are mapped to the predefined angular range (ΔA) at equal angular intervals. The method according to claim 2.

4. The series of adjacent angular positions extend to an angular sub-range of 5% to 50% or 10% to 40% of the predefined angular range (ΔA). The method according to claim 2.

5. The predefined set ([AP]) includes a first subset ([PAP]) of primary angular positions and a second subset ([SAP]) of secondary angular positions distributed between the primary angular positions, wherein the selected angular position is sequentially selected from the primary angular positions within the first subset ([PAP]), and the method further includes: If consistent capping performance is detected at the selected angular position, select at least one second angular position from the second subset ([SAP]) (201B), the at least one second angular position being spatially adjacent to the selected angular position, For each of the selected secondary angular positions, the capping machine (3) is operated (100), and further multiple capping operations are performed, and the consistent capping performance at the selected secondary angular positions is evaluated by further multiple capping operations (202). Equipped with, The termination condition (204) for detecting the consistent capping performance for the series of adjacent angular positions requires the detection of the consistent capping performance at each selected second angular position. The method according to claim 1.

6. The first subset ([PAP]) includes an ordered sequence of the primary angular positions, and the selected angular positions are sequentially selected from the first subset according to the ordered sequence of the primary angular positions. The method according to claim 5.

7. The first subset ([PAP]) includes a first subsequence (SS1) of primary angular positions ordered by magnitude, and a second subsequence (SS2) of primary angular positions ordered by magnitude, which are arranged alternately with the primary angular positions of the first subsequence (SS1), wherein the second subsequence (SS2) follows the first subsequence (SS1) in the first subset ([PAP]). The method according to claim 6.

8. The aforementioned predefined set ([AP]) includes 4 to 12 primary angular positions, The method according to claim 5.

9. The second subset ([SAP]) includes at least one second angular position between each pair of spatially adjacent first angular positions in the first subset ([PAP]), The method according to claim 5.

10. The termination condition (203) requires the detection of consistent capping performance at one or more selected secondary angular positions smaller than the selected angular position and one or more selected secondary angular positions larger than the selected angular position. The method according to claim 5.

11. The process further includes acquiring an input signal (S1) indicating the rotational path length of the plurality of caps (10) during the plurality of capping operations (202), wherein the rotational path length is evaluated to detect the consistent capping performance. The method according to claim 1.

12. The consistent capping performance is detected when the variation in the rotation path length is less than the variation threshold. The method according to claim 11.

13. The aforementioned consistent capping performance is further detected when all rotational path lengths are below a length threshold (TH1). The method according to claim 12.

14. The capping machine is operated to perform multiple capping operations at the selected angular position, while the rotation path length of the cap (10) relative to a length threshold (TH1) is evaluated (104), and the multiple capping operations are stopped when at least one rotation cap length exceeds the length threshold (TH1), and another angular position is sequentially selected from a predefined set ([AP]), further comprising: The method according to claim 11.

15. In relation to the variation constraint (ΔL), the further includes evaluating collectively (403) the rotational path length of the multiple caps (10) between multiple capping operations at each of the series of adjacent angular positions, and The termination condition (204) further includes requiring the satisfaction of the variation constraint, The method according to claim 11.

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