Patent Application
20180002133
The disclosure relates to the field of automated knitting, and in particular, to feeding material to a knitting machine.
Knitting is performed in order to create complex textiles and fabrics. In order to save labor costs when knitting particularly complex fabrics (e.g., those that include metal wires or other non-standard threads), it is common to utilize an automated knitting machine. An automated knitting machine may be used, for example, to knit complex patterns into a unified fabric based on input from a controller.
While automated knitting machines operate, they draw thread from one or more spools. The speeds at which threads are drawn may vary depending on the type of design being knitted, as well as whether the knitting machine is knitting in a “forward” or “backwards” direction. The speeds may also vary over time as the knitting machine uses more or less of a given thread.
Knitting machines remain desirable for a number of uses, but their utility when knitting fabrics that include exotic threads/filaments is limited. Certain threads may snap if they experience more than even a few centiNewtons (cN) of tension, which is undesirable because a broken thread results in substantial time delays as re-threading takes place. Furthermore, the programs utilized by knitting machines do not take into account the types of threads being actively knitted. Hence, apart from directing a knitting machine to operate very slowly (which is not economical), these problems with utilizing exotic threads are unavoidable.
Embodiments described herein present enhanced feeding mechanisms for automated knitting machines. These feeding mechanisms dynamically respond to the changing and unpredictable feeding speeds of a knitting device of a knitting machine, ensuring that tension applied to a thread being fed to a knitting device does not exceed a threshold level.
One embodiment is a thread feeding device which includes a spool that supplies thread to a knitting device through a thread path and a motor that drives the spool. The device and further includes a mobile guide in the thread path that changes position due to changes in thread tension as the knitting device draws thread through the mobile guide. The thread feeding device also includes a sensor that measures a change in position of the mobile guide, and a controller that determines an amount of tension applied to the thread by the knitting device based on the change in position, and adjusts a speed of a motor that drives the spool based on the amount of tension.
Another embodiment is a method. The method includes measuring thread tension as the thread is fed into a knitting device, and controlling a speed at which the thread is fed into the knitting device based upon the measured thread tension.
Another embodiment is a non-transitory computer readable medium embodying programmed instructions which, when executed by a processor, are operable for performing a method. The method includes measuring thread tension as the thread is fed into a knitting device, and controlling a speed at which the thread is fed into the knitting device based upon the measured thread tension.
Other exemplary embodiments (e.g., methods and computer-readable media relating to the foregoing embodiments) may be described below. The features, functions, and advantages that have been discussed can be achieved independently in various embodiments or may be combined in yet other embodiments further details of which can be seen with reference to the following description and drawings.
Some embodiments of the present disclosure are now described, by way of example only, and with reference to the accompanying drawings. The same reference number represents the same element or the same type of element on all drawings.
The figures and the following description illustrate specific exemplary embodiments of the disclosure. It will thus be appreciated that those skilled in the art will be able to devise various arrangements that, although not explicitly described or shown herein, embody the principles of the disclosure and are included within the scope of the disclosure. Furthermore, any examples described herein are intended to aid in understanding the principles of the disclosure, and are to be construed as being without limitation to such specifically recited examples and conditions. As a result, the disclosure is not limited to the specific embodiments or examples described below, but by the claims and their equivalents.
Thread feeding device 200 further comprises thread path 220. As illustrated in
Sensing element 227 is attached to arm 224, and therefore changes position as mobile guide 223 translates along arc 229. Sensor 228 (e.g., a potentiometer) measures the motion of sensing element 227, and determines an amount of translation of mobile guide 223 along arc 229. This information may then be provided to controller 218, which may determine an amount of tension applied to thread 230 by a knitting device 140 proximate to mobile guide 223, and controls a speed of motor 214 based on this information.
Illustrative details of the operation of thread feeding device 200 will be discussed with regard to
As knitting machine 100 draws thread 230 at a changing rate over time, knitting machine 100 generates varying levels of force at thread 230. Mobile guide 223, which is located in thread path 220 between spool 210 and knitting device 140, changes position (e.g., translates) in response to changes in thread tension as knitting device 140 draws thread 230 through mobile guide 223 (step 302). The change in position of mobile guide 223 causes arm 224 to rotate about point 226, and this displacement is detected by sensing element 227 of sensor 228. In this manner, sensor 228 measures the change in position of mobile guide 223 (e.g., from a default position P1) (step 304).
Controller 218, upon receiving input from sensor 228 indicating the change in position of mobile guide 223, proceeds to determine an amount of tension applied to thread 230 by knitting device 140 based on that change in position (step 306). For example, controller 218 may consult one or more predefined maps correlating data from sensor 228 to speeds for motor 214. A map may be defined to control motor speeds based on tension levels associated with each of multiple levels of sensor input. In this manner, by consulting a map, controller 218 determines the amount of tension applied by knitting device 140.
Controller 218 further proceeds to adjust a speed of motor 214, which is driving spool 210, based on the amount of tension (step 308). For example, controller 218 may adjust the speed of motor 214 based on data stored in a predefined map in memory, in order to reduce the amount of tension applied to thread 230, in effect changing the amount of tension based on the difference between the amount of tension and a desired tension value.
Utilizing method 300, the amount of tension applied to thread 230 may be beneficially controlled, even in environments where a knitting machine draws out thread 230 at varying and unpredictable rates. This ensures that thread 230 does not break or become tangled. Furthermore, since mobile guide 223 translates in response to increased drawing speed from knitting device 140, this has the effect of providing a buffer period that enables thread feeding device 200 to account for hysteresis (e.g., time delays) at motor 214 and other elements of thread feeding device 230.
In the following examples, additional processes, systems, and methods are described in the context of a knitting machine that utilizes a dynamic thread feeding device.
Having initialized, controller 218 proceeds to read sensor 228 (step 504). Depending on the input provided from sensor 228, controller 218 determines whether the value is below a minimum value (e.g., a “resting” value when thread feeding device 200 is not feeding thread 230 to knitting machine 100) (step 506). If the value is below the expected range (e.g., as indicated in the loaded map), then controller 218 determines that thread 230 is missing or broken (step 522), and reports an error condition (step 524).
Alternatively, an idle switch has been set at knitting machine 100, then an idle condition may be detected (step 508). Thus, controller 218 engages in additional processing by reviewing a direction switch set by an operator (indicating the direction in which knitting is occurring at knitting machine 100) (step 526), checking a speed selection indicated by the operator (step 528), and setting motor speed ranges for motor 214 (step 530). If controller 218 detects that a jog switch is set (step 532), then controller 218 sets motor 214 to a constant speed (step 534). This jog operation may help an operator to initially set up thread feeding device 200 before knitting machine 100 engages in operation where active knitting takes place.
If an idle condition is not detected in step 508, controller 218 determines whether or not sensor input indicates a tension value within an expected range (step 510). If the tension value is within the expected range, then controller 218 maps the sensor value to a motor speed value (as indicated by a map) (step 518), and proceeds to adjust the speed of motor 214 to the mapped value (step 520). Alternatively, if the tension value is above the expected range, controller 218 sets motor 214 to the highest speed available in order to rapidly reduce tension and avoid a break (step 512). However, if the tensions is above a maximum threshold value (step 514), then controller 218 detects a tangled thread (step 516), and proceeds to stop motor 214 and report an error condition (step 524). The error condition may be reported, for example, via a display (not shown).
Thread feeding device 640 further includes member 674, which is attached to support 614, and frame 672. Rollers 670 are attached to frame 672, and define a thread path 699 for thread 698 to follow as it travels from spool 650 to knitting device 630. Sensor 680 includes a sensing element 682 for sensing deflection/translation of mobile guide 696, by measuring a position of arm 694. Bar 690 is attached to arm 694, and is held to a default position in low-tension operations by biasing spring 692.
Referring more particularly to the drawings, embodiments of the disclosure may be described in the context of an aircraft manufacturing and service method 700 as shown in
Each of the processes of method 700 may be performed or carried out by a system integrator, a third party, and/or an operator (e.g., a customer). For the purposes of this description, a system integrator may include without limitation any number of aircraft manufacturers and major-system subcontractors; a third party may include without limitation any number of vendors, subcontractors, and suppliers; and an operator may be an airline, leasing company, military entity, service organization, and so on.
As shown in
Apparatus and methods embodied herein may be employed during any one or more of the stages of the production and service method 700. For example, components or subassemblies corresponding to production stage 708 may be fabricated or manufactured in a manner similar to components or subassemblies produced while the aircraft 702 is in service. Also, one or more apparatus embodiments, method embodiments, or a combination thereof may be utilized during the production stages 708 and 710, for example, by substantially expediting assembly of or reducing the cost of an aircraft 702. Similarly, one or more of apparatus embodiments, method embodiments, or a combination thereof may be utilized while the aircraft 702 is in service, for example and without limitation, to maintenance and service 716. For example, the techniques and systems described herein may be used for steps 706, 708, 710, 714, and/or 716, and/or may be used for airframe 718 and/or interior 722. These techniques and systems may even be utilized for systems 720, including for example propulsion 724, electrical 726, hydraulic 728, and/or environmental 730.
In one embodiment, knitting machine 100 generates knitted fabrics for use with interior 722, and fabricates these fabrics during component and subassembly manufacturing 708. The fabrics may then be assembled into an aircraft in system integration 710, and then be utilized in service 714 until wear renders the fabrics unusable. Then, in maintenance and service 716, fabrics may be discarded and replaced with a newly manufactured fabric. Thread feeding device 200 may be utilized by knitting machine 100 while fabricating new fabrics, to enhance the overall manufacturing speed of those fabrics.
Any of the various control elements (e.g., electrical or electronic components) shown in the figures or described herein may be implemented as hardware, a processor implementing software, a processor implementing firmware, or some combination of these. For example, an element may be implemented as dedicated hardware. Dedicated hardware elements may be referred to as “processors”, “controllers”, or some similar terminology. When provided by a processor, the functions may be provided by a single dedicated processor, by a single shared processor, or by a plurality of individual processors, some of which may be shared. Moreover, explicit use of the term “processor” or “controller” should not be construed to refer exclusively to hardware capable of executing software, and may implicitly include, without limitation, digital signal processor (DSP) hardware, a network processor, application specific integrated circuit (ASIC) or other circuitry, field programmable gate array (FPGA), read only memory (ROM) for storing software, random access memory (RAM), non-volatile storage, logic, or some other physical hardware component or module.
Also, an element may be implemented as instructions executable by a processor or a computer to perform the functions of the element. Some examples of instructions are software, program code, and firmware. The instructions are operational when executed by the processor to direct the processor to perform the functions of the element. The instructions may be stored on storage devices that are readable by the processor. Some examples of the storage devices are digital or solid-state memories, magnetic storage media such as a magnetic disks and magnetic tapes, hard drives, or optically readable digital data storage media.
Although specific embodiments are described herein, the scope of the disclosure is not limited to those specific embodiments. The scope of the disclosure is defined by the following claims and any equivalents thereof.
