Circular weft knitting machine

Abstract: Improved apparatus and technique for the circular weft knitting of articles including an improved knitting machine control synchronization system for computer control operation using independently operable, modular components. Needle selection for knit, tuck or float operation is effected by a unique presser cam system which flexes the lower end of compound needles outwardly where they are selectively and magnetically held or released according to a prescribed program to enter one or one set of plurality of cam tracks (3120) depending on the intended function of the needle. The upper end of the needles are positively engaged and held at a prescribed position above the fulcrum (3108) during such selection operation. A modified sinker element (2090) and sinker drive system accommodate an increased range of stitch length control and compensate for variations in yarn elasticity. The yarn knitting cylinder is directly driven by a hollow core motor concentrically arranged with respect to the longitudinal axis (1904) of the knitting cylinder. Finally there is provided an improved laser yarn cutting system.

Description: The present invention is directed to circular weft knitting machines, and more particularly to improvements in certain operating areas of the type of circular knitting machine previously described in EP-A-0099269. The above-described earlier filed patent application is directed to a relatively new and unique knitting system which provides each needle member with the selective capability of performing a knit, tuck, or float operation at each yarn feed location independent of the direction of knitting needle approach thereto and at speeds previously unattainable. The knitting machine described earlier utilizes compound needle elements, unique sinker elements, substantially unbroken continuous cam tracks, an improved yarn feed system, means for monitoring yarn consumption and effecting adjustments in actual stitch length and response thereto, and a unique processor control knitting system. All of the above features provide for the economic and high speed fabrication of variously shaped and/or patterned tubular knitwear items such as hosiery of both the sock and stocking categories, selectively patterned fabrics, and the like. During subsequent development of the aforesaid knitting apparatus, it has been determined that certain operating areas thereof can be improved or enhanced to provide for: a more simplified construction; a more economic fabrication; an enhanced operational control; an enhanced reliability of operation; and an expanded field of utility. In general the areas of the knitting machine according to the present invention wherein significant structural and functional modifications have been introduced comprise methods and systems for the operational control thereof. From one aspect, the invention is directed to a method for the operational control, by means of a microprocessor, of a circular weft knitting machine that includes a rotatable knitting needle support cylinder having a multiplicity of stitch forming elements mounted thereon to knit an article of particular character, of the type generally disclosed in EP-A-0099269 and EP-A-0026425, and as defined in the precharacterising clause of claim 1, the method including the steps of: (a) introducing digital data at separated intervals indicative of a monotonically increasing schedule of instruction steps for fabrication of said particular article on to a special communication bus; and (b) continuously introducing digital data indicative of the current position and velocity of the knitting needle support cylinder on to said special communication bus. As defined in the characterising clause of claim 1, the method is characterised by: (c) controlling the operation of said stitch forming elements to knit, tuck, or float in accord with a first set of locally generated selective commands responsive to the composite digital data on said special communication bus and a first set of stored instructions uniquely relating to the fabrication of said particular article; (d) controlling the engagement of yarns by said stitch forming elements in accord with a second set of locally generated selective commands responsive to the composite digital data on said special communication bus and a second set of stored instructions uniquely relating to the fabrication of said particular article; (e) controlling the displacement and velocity of said knitting needle support cylinder in accord with a third set of locally generated selective commands responsive to said instruction step digital data present on said special communication bus and a third set of stored instructions uniquely relating to the fabrication of said particular article; and (f) selectively releasing the individual steps of said monotonically increasing schedule of instruction steps in response to the presence of said knitting cylinder position information on said special communication bus and a fourth set of stored instructions uniquely relating to the fabrication of said particular article. From another aspect, the invention consists in a microprocessor-controlled control system for a high speed circular weft knitting machine of the type generally disclosed in EP-A-0099269 and EP-A-0026425, and as defined in the precharacterising clause of claim 5, that includes a rotatable knitting needle support cylinder having a multiplicity of stitch forming elements mounted thereon to knit an article of particular character, said system operating responsive to the precise position and velocity of said support cylinder, said system further including: (a) a multi-line communication bus; (b) machine managing module means for introducing digital data at separated intervals indicative of a monotonically increasing schedule of instruction steps for fabrication of said particular article on to said communication bus; and (c) motor control module means for continuously introducing digital data indicative of the current position and velocity of the knitting needle support cylinder on to said communication bus; (d) said machine managing module means further releasing the individual steps of said monotonically increasing schedule of instruction steps in response to the presence of said knitting cylinder position information on said communication bus and a fourth set of stored instructions uniquely relating to the fabrication of said particular article. As defined in the characterising clause of claim 5, the system is characterised by: (e) needle control module means for controlling the operation of said stitch forming elements to knit, tuck or float in accord with a first set of locally generated selective commands responsive to the composite digital data on said communication bus and a first set of stored instructions uniquely relating to the fabrication of said particular article ; and (f) yarn control module means for controlling the engagement of yarns by said stitch forming elements in accord with a second set of locally generated selective commands responsive to the composite digital data on said special communication bus and a second set of stored instructions uniquely relating to the fabrication of said particular article; (g) said motor control module further controlling the displacement and velocity of said knitting needle support cylinder in accord with a third set of locally generated selective commands responsive to said instruction step digital data present on said multi-line communication bus and a third set of stored instructions uniquely relating to the fabrication of said particular article. Reference is also made to US-A-3,825,900, which discloses a system incorporating feature (e) of claim 5 recited above. Reference will now be made to the accompanying drawings, in which:- Figure 1 is an oblique view schematically illustrative of the assembled machine described in EP-A-0099269, partially cutaway to show the relative positioning and general structural interrelationship of certain of the major components thereof; Figure 2 is a vertical section with the lower portion as taken on the line 2-2 of Figure 3 and the upper portion as taken on line 2A-2A of Figure 4; Figure 2A is an enlarged sectional view of the upper portion of the machine shown on Figure 2; Figure 3 is a horizontal section as taken on the line 3-3 of Figure 2; Figure 4 is a horizontal section as taken on the line 4-4 of Figure 2; Figure 5a is a top plan view, partially broken away as taken looking down from the top of Figure 2; Figure 5b is a vertical section, with a portion thereof rotated for clarity of showing, as taken along the line of 5b-5b of Figure 5a; Figure 6 is an elevational view of a presently prepared configuration for the knitting needle support cylinder; Figure 7 is an enlarged view of the slot configuration shown on Figure 8; Figure 8 is a section taken on the line 8-8 of Figure 6; Figure 9 is a side elevation, partially in section, of a presently preferred construction of a flexible shank compound needle element; Figure 10 is a plan view of the needle element illustrated in Figure 9; Figure 11 is a side elevation of a presently preferred flexibile shank closing element for the needle element illustrated in Figure 9 and Figure 10; Figure 12 is a plan view of the closing element illustrated in Figure 11; Figure 13a is a schematic representation of the shape of the presently preferred cam track control paths for two available modes of composite vertical and horizontal needle element displacement for a 60° operating sector intermediate adjacent yarn feed locations; Figure 13b is a schematic representation of the shape of the presently preferred cam track control paths for the two available modes of composite vertical and horizontal needle closing element displacement for a 60° operating sector intermediate adjacent yarn feed locations; Figure 13c is a schematic representation of the presently preferred cam track control path for composite vertical and horizontal displacement of the sinker elements for a 60° operating sector intermediate adjacent yarn feed locations; Figure 13d is a schematic representation of the shape of the presently preferred cam track control path for the composite vertical and horizontal displacement of the rake elements for a 60° operating sector intermediate adjacent yarn feed locations; Figure 13e is a schematic representation of the shape of the presently preferred cam track control path for the composite vertical and horizontal displacement of the terry instrument for a 60° operating sector intermediate adjacent yarn feed locations; Figure 13f is a vertically split and horizontally unwrapped schematic vertical section that, when appropriately merged together, shows the relative vertical positioning of the needle, element, closing element, sinker element, terry instrument and rake element during their composite vertical and horizontal displacement intermediate adjacent yarn feed locations and resulting from the control cam track paths shown in Figures 13a to 13e. Figure 13g is a schematic horizontal view that shows the relative radial (horizontal) positioning of the rake element, sinker element, terry instrument and shedder as the knitting cylinder element is rotated intermediate adjacent yarn feed locations. Figures 14(1) through 14(18) are simplified schematic representations sequentially showing the relative positioning of the yarn engaging elements at the successively indicated angular locations with a 60° operating sector in general accord with the control paths depicted in Figure 13. Figure 15a is a plan view, partially in section of a presently preferred construction for a magnetic retention assembly; Figure 15b is an elevational view as taken on the line 15b-15b on Figure 15a; Figure 15c is a partial and enlarged vertical section as taken on the line 15c-15c on Figure 15a; Figure 15d is a section on line 15d-15d of Figure 15a. Figure 16 is an oblique view of the presently preferred configuration for the presser cam; Figure 16b is a plan view of the presser cam illustrated in Figure 13a; Figure 16c is a side view of the presser cam illustrated in Figure 13a; Figure 17 is a plan view of the presently preferred configuration for the sinker element; Figure 18a is a side elevational view of a presently preferred configuration for a rake element; Figure 18b is a plan view of the rake element shown in Figure 18a; Figure 18c is an enlarged sectional view showing the mounting of the rake assembly in the outer rake cam sleeve member; Figure 19 is a side elevation of a presently preferred configuration for a terry instrument; Figure 20 is a side elevation, partially in section, of a presently preferred construction for a yarn feed assembly; Figure 21 is a plan view, partially in section, of the yarn feed assembly components illustrated in Figure 20; Figure 22 is a section taken on the line 22-22 of Figure 21; Figure 22A is a typical section as taken on the line A-A of Figure 22; Figure 23 is a section taken on the line 23-23 of Figure 21; Figure 24 is a developed view of the track control cam taken on the line 24-24 of Figure 21; Figure 25 is a section taken on the line 25-25 of Figure 21; Figure 26A is a schematic sectional view of the yarn clamping members included in the yarn feed assembly; Figure 26B is a schematic elevation view of the moveable jaw member support element included in the yarn feed assembly as viewed from line B-B in Figure 26A. Figure 26C is a schematic plan view as viewed from line C-C on Figure 26A showing the surface configuration of the clamping members; Figure 27 is a top view, partially in section, of the body yarn use monitor assembly; Figure 28 is a section taken on the line 28-28 of Figure 21; Figure 29 is a section taken on the line 29-29 of Figure 21; Figure 29A is a plan view of the yarn selection carrier arm showing details thereof omitted from Figure 21 in the interests of clarity. Figure 29B is a section taken on the line B-B of Figure 29; Figure 29C is an enlarged view, partially in section of the yarn engaging jaw components at the end of the yarn selection carrier arm; Figure 29D is an enlarged elevation, partially in section, as generally taken on the line D-D of Figure 29C; Figure 29E and 29F are details showing the two position detent control elements for jaw positioning; Figure 29G is a detail as generally taken on the line G-G of Figure 29; Figure 30 is a simplified block diagram of a knitting system in which a plurality of knitting machine units are controlled from a central system computer; Figures 31A and 31B are a composite simplified block diagram of a knitting machine unit of Figure 30; Figure 32 is a schematic diagram of a bipolar coil driver of Figure 31. Figures 33A, B, and C are voltage and current curves to which reference will be made in describing the wave shapers of Figure 31; Figure 34 is a block schematic diagram of a main motor controller of Figure 31; Figure 35A through 35C are curves to which reference will be made in describing the operation of the main motor controller of Figure 34; Figure 36 is a logic diagram of a forward-reverse decoder of Figure 31; Figure 37 is an oblique view schematically illustrative of a presently preferred and somewhat modified construction for a circular weft knitting machine incorporating the principles of this invention; Figures 38A and 38B are vertical sections of the upper portion and the lower portion of the knitting machine shown in Figure 33 and depicting, on the left hand side thereof, component positioning at a selection point intermediate a pair of yarn feed locations and, on the right hand side component positioning at a yarn feed location; Figure 38C is a horizontal section as taken on the line C-C on Figure 38B; Figure 39 is a sector shaped horizontal section as taken on the line 39-39 on Figure 38A; Figure 40 is a sector shaped horizontal section as taken on the line 40-40 on Figure 38A; Figure 41 is a sector shaped horizontal section as taken on the line 41-41 on Figure 38A; Figure 42 is a development taken along the line 42-42 in Figure 41; Figure 43 is a side elevation of an improved sinker element configuration; Figure 44 is a side elevation, partially in section, of a presently preferred configuration for a flexible shank needle element; Figure 45 is a plan view of the needle element illustrated in Figure 44; Figure 46 is a side elevation of a presently preferred configuration for a flexible shank closing element for the needle element illustrated in Figure 44 and 45; Figure 47 is a partial vertical section through the knitting cylinder; Figure 48 is partial side elevational view, with the knitting cylinder removed, of a presser cam assembly; Figure 49 is a partial vertical section as taken on the line 49-49 of Figure 48; Figure 50 is a partial horizontal section taken on the line 50-50 of Figure 49; Figure 51 is a partial horizontal section taken on the line 51-51 of Figure 49; Figure 52 is a schematic block diagram of a knitting machine control system incorporating the principles of this invention; Figure 53 is a schematic side elevation of a laser yarn cutting assembly. The hereinatter described improved machine construction operates and functions in essentially the same manner as that described in detail in conjunction with the embodiment illustrated in Figures 1-36 as described in EP-A-0099269 Figures 37 through 53 relate to alternative and presently preferred constructions for certain operating areas of the circular weft knitting machine illustrated in Figures 1-36. The presently preferred construction reflects various modifications and improvements in structure and related function directed to the ends of simplification of construction, permitted economies in fabrication, enhanced operational control, enhanced reliability of operation, and an expanded field of utility. In light thereof, the hereinafter set forth machine description will be essentially directed only to the modified component structures and to the functions and modes of operations attendant thereto and, to the extent possible in the interest of both clarity and brevity, redundancy of description with that set forth in conjunction in the heretofore described machine will be avoided. The description of Figures 1-36 set forth in EP-A-0099269. It should be understood, however, that implicit reliance will be placed upon the preceding detailed description of the knitting machine embodying the principles of the invention for satisfaction of the statutory requirements of adequacy of disclosure. The following portions of this disclosure will be premised upon an assumed awareness and understanding of both the basic structure and modes of operation of the previously described circular weft knitting machine. Referring initially to Figure 37, the presently preferred construction includes a selectively contoured main support plate 1900 mounted on a cabinet like base 1902 which is adapted to contain the power supplies for the main drive motor and the computer, the vacuum take-down turbine for sock delivery and the associated sock delivery mechanisms none of which are believed to be of novel character and are not further described herein. The support plate 1900 includes a central sock delivery bore (not shown) having a vertical longitudinal axis 1904, which serves as the common vertical longitudinal axis for the hereinafter described machine components mounted on the support plate 1900. Mounted on the support plate 1900 is an elongate and generally cylindriccal motor housing 1906, a reduced diameter frame or housing section 1908 for the knitting components having drive system appendage 1910 extending therefrom and for mounting certain of the selection system components 1914. Mounted thereabove is a portion of the housing 1916 enclosing the sinker assembly. Disposed above the sinker assembly housing 1916 and supported by a pair of standards 1918 and 1920 is a platform 1922 that houses the yarn feed mechanisms and various dial mechanisms 1924 for terry loop formation, radial dial needles and the like. Appendage 1910 accommodates the drive for the auxiliary drive shaft 2016 for transmitting operative power to the overlying components in housing 1924. Also schematically depicted on Figure 37 is a laser yarn severing system which includes a CO₂ laser 1928 whose beam is directed through a conduit 1930 and after reflection by mirrors 1932 and 1934 is impinged on a rotating mirror positioned on vertical longitudinal axis 1904, which directs the laser beam to an appropriate location for yarn severance. As indicated above, the presently preferred constructions are directed only to certain machine component areas. Such areas as to where modification has been effected will be hereinafter individually described, it being presumed that such constitutes a supplement to the basic construction and modes of operation that were set forth in detail in the earlier portion of this specification. Basic Machine Organization and Machine Drive System As best shown in Figures 38A, 38B and 38C the presently preferred construction includes an improved and simplified arrangement and drive system for the knitting needle support cylinder and for an improved sinker assembly associated therewith. To the above ends, there is provided a brushless, hollow core, electronically commutated, rare earth magnet type main drive motor 2020 (preferably of a 20 kw size) disposed in concentric surrounding relation to the longitudinal machine axis 1904. Motors of this general type are commercially obtainable from Clifton Precision Co. of Philadelphia, Pennsylvania and from Motion Control Systems of Radford, Virginia. The main drive motor 2020 is utilized in association with a high precision hollow core resolver 2021 and a rotary transformer position read out device 2023 for motor rotor position control purposes. The motor 2020 includes a cylindrical housing 2024 having a plurality of cooling fins 2026 extending outwardly therefrom. Disposed within the housing 2024 is a cylindrical stator 2022 containing the motor windings 2028. Disposed within the stator 2022 and positioned in closely spaced interfacial relation therewith is a rotor element made up of a cylindrical assemblage 2030 of rare earth(Sm/Co) magnets mounted on a cylindrical rotor element 2032. Mounted on the upper end of the rotor element 2032, as by a securely interlocked threaded interengagement 2040, is the lower end of a rotatable knitting needle support cylinder 2042. Interlocking of the motor rotor 2032 with the knitting needle suport cylinder 2042 is effected by the interposition of a bearing clamping ring 2043, whose shoulder 2045 also performs a support function for the main cylinder bearing 2070, as will be hereinafter described. The direct interconnection of the motor rotor element 2032 with the knitting needle support cylinder 2042 permits the latter to be rotatably displaced in direct accord with, and in direct response to, controlled displacement of main drive rotor element 2032. Such direct drive affords reduced polar moment of intertia, eliminates backlash, and substantially increases torsional stiffness. In addition, the use of such a hollow core rotor 2032 permits direct finished sock delivery through the drive motor 2020 with attendant elimination of gear trains and the like on the drive system. The knitting needle support cylinder 2042 is of essentially the same general configuration as that described in the initially described embodiment and contains a plurality of longitudinally disposed radial slots 2047 on its outwardly facing surface, each of which is adapted to contain the guide the path of displacement of individually displaceable compound needle elements, generally designated 2049. A ring drive gear 2044 is mounted in encircling splined relation on the outer surface of the knitting needle support cylinder 2042 near the upper end thereof. The ring drive gear 2044 intermeshes with and drives an associated gear 2046 which is mounted on and keyed to the auxiliary drive shaft 2016 for transmittal of motive power to the machine components associated with the overlying platform 1922. As will now be apparent, the displacement of the auxiliary drive shaft 2016 is always in direct accord with and is directly mechanically synchronized with the displacement of the knitting needle support cylinder 2042, with advantages akin to those above noted. Disposed within the knitting needle support cylinder 2042 and positioned in close interfacial relation thereto is the outer surface of a non-rotatable stationary inner cam track sleeve member 2050. As was previously described earlier in more detail in conjunction with the inner cam track sleeve member 78, and as shown on the right hand side of Figure 38A, the inner cam track sleeve member 2050 includes an upper cam track 2052 and a lower cam track 2054 on the outer surface thereof facing the knitting cylinder for accommodation of the extending butt portions on the lower ends of the closing element and needle elements respectively. Disposed in surrounding close interfacial relation with the outwardly facing surface of the knitting needle support cylinder 2042 is the inner face of a non-rotatable, outer cam track face 2059 mounted in a stationary outer frame member 2060. The face 2059 contains an upper cam track 2062 and a lower cam track 2064 for accommodation of the extending butt portions on the lower ends of the closing elements and needle elements respectively similar to that earlier described for cam track sleeve 86 in the previously disclosed embodiment. In the herein disclosed embodiment the cam tracks 2062 and 2064 could be formed on the interior surface of the frame member 2060, thus obviating the need of a separate insert as a supportive element therefore. As such, it performs the same compound needle control functions as the earlier described outer cam track sleeve member 86. Additionally, however, the frame member 2060 here forms part of the housing of the machine and, as will be hereinafter described, performs additional support functions for other machine components as, for example, with respect to both sinker assembly support and sinker assembly displacement for stitch length control purposes. As depicted on the left hand side of Figure 38A,. the outer cam tracks 2062 and 2064 in the vicinity of the selection points may function merely as recesses within which the needle and closing element butts can be accommodated, if necessary. As will later become more apparent, the locus of control of the vertical location of the needle and closing element in the vicinity of the selection points has been shifted from the cam butts on the dependent ends of the needle and closing elements to the locus of auxiliary cam butts located near the upper ends of the needle and closing elements. To this end the controlled vertical positioning of the needle and closing elements in the vicinity of the selection points in the presently preferred knitting machine construction is primarily controlled by the disposition of auxiliary butts located near the upper ends of the needle and closing elements within an auxiliary channel. In accord therewith the cam tracks 2062 and 2064 may be made oversized in vertical extant or, if desired, may even be omitted completely in such selection point areas. The knitting needle cylinder 2042 is rotatably mounted relative to the inner sleeve member 2050 and outer frame member 2060 by the interengagement of support shoulder 2066 at its lower end with the moveable inner race 2068 of the main cylinder support bearing 2070 and by the complemental support action of the shoulder 2045 on the bearing clamping ring 2043. The main cylinder support bearing 2070, which is preferably an "X contact" type of ballbearing, has its fixed outer race 2072 secured to the frame member 2060 through shoulder 2073 and retaining ring 2074. In a similar manner the upper end portion of the knitting needle support cylinder 2042 is connected to the inner cam track sleeve support bearing 2078 through interengagement of shoulder 2080 with the outer rotatable race 2076 thereof and retaining ring 2082. The inner cam track sleeve support bearing 2078, which again is preferably an "X contact" type ball bearing, is connected to the stationary inner cam track sleeve 2050 through interengagement of shoulder 2084 and retaining ring 2088 with the inner stationary race 2086 thereof. As will now be apparent, the presently preferred machine construction includes a simplified and improved main drive system wherein the knitting needle support cylinder 2042 is fixed in elevation and the rotative displacement thereof relative to the stationary inner cam tracks 2052 and 2054 and to the stationary outer tracks 2062 and 2064 is in directly coupled axial synchronism with the rotor 2032 of the main drive motor 2020. Additionally the drive power transmitted through the auxiliary drive shaft 2016 is directly synchronized with rotative displacement of the knitting needle support cylinder 2042 with the interposition of only one mechanical gear set (2044, 2046) therebetween. SINKER ASSEMBLY The presently preferred embodiment includes an improved construction for a sinker assembly that not only provides selectively controlled three dimensional sinker element displacement in conjunction with needle element displacement, but also provides for control of stitch length by variation in sinker assembly elevation relative to a fixed elevation knitting needle support cylinder 2042 and automatic compensation for variation in stitch length through accurate position control of the stitch loop during upward needle element displacement to accommodate the knitting of a wide variety of non-stretch spun yarns over a wide range of stitch lengths. Referring now to Figures 38A to 43, mounted on the top of the stationary outer frame member 2060 is a sinker assembly, generally designated 2090, a portion of which is adapted to rotate in synchronism with the knitting needle support cylinder 2042 but to be independently vertically displaceable relative thereto for stitch length control purposes. To the above end and as best shown in Figures 38A through 41, the presently preferred construction includes an annular disc shaped sinker assembly support plate 2092 mounted on the upper end of the stationary outer frame member 2060. The sinker assembly support plate 2092 includes an annular generally disc shaped upper body portion 2094 having a first dependent cylindrical flange or skirt portion 2096 disposed within an annular recess 2098 in the upper surface of the outer frame member 2060. The first dependent skirt portion 2096 is disposed in splined relation 2097 with the recess 2098 so as to preclude any rotatable displacement thereof relative to the knitting needle support cylinder 204 but yet permit vertical displacement of the support plate 2092 as a unit relative to the outer frame member 2060 and the knitting needle support cylinder 2042. Adjacent to the outer marginal edge of the sinker assembly support plate 2092 is a second dependent flange 3000 having a threaded interior surface 3002. Positioned in spaced facing relation with the threaded surface 3002 is an exterior threaded surface portion 3004 of the outer frame member 2060. Disposed intermediate the threaded surfaces 3002 and 3004 is an elevator ring 3006 having a sector gear 3008 extending from one portion of the base thereof. The threaded surfaces 3002 and 3004 have differing thread pitches so that the limited rotative displacement of the sector gear 3008 by a separate drive gear (not shown) and a concommitant limited rotation of the elevator ring 3006 relative to the frame member 2060 will effect an amplified vertical displacement of the sinker assembly support plate 2092. The vertical displacement of the sinker assembly support plate 2092 will, as hereinafter described, effect a corresponding vertical displacement of the entire sinker assembly mounted thereon. Referring now to Figures 38A and 40, the support plate 2092 includes a marginal edge 3010 on upper body portion 2094 thereof. Supported thereon is a ring shaped frame element 3012 which in turn supports, in association with a spacer ring 3014, the outer fixed race 3016 of the sinker assembly support bearing 3018. Bolted to the frame element 3012 and spacer ring 3014 is an upper vertical elevation sinker cam ring 3020 having a vertical control cam surface 3022 overlying the upper edge portion 3024 of the body of a selectively shaped sinker element 3026. As will be apparent, the upper sinker cam ring 3020 is nonrotatable and its elevation will be determined by the elevation of the sinker assembly support plate 2092. Referring now to Figures 38A and 43, the presently preferred configuration for the sinker element 3026 includes a rectangular body portion 3030 having an elongate arcuate nose portion 3032 extending from one side thereof. Overlying the upper end of the nose portion 3032 is a generally triangularly shaped segment 3034 providing an upwardly facing inclined surface or land 3036 which leads to a horizontal land 3037. Disposed beneath the inclined surface 3036 is a relatively deep hook like segment 3038 and an adjacent land 3040. The upper marginal edge 3024 is the rectangular body portion 3030 constitutes a cam follower surface adapted to be disposed in sliding contact with with overlying cam control surface 3022 on the upper sinker cam ring 3020. Dependent from the underside of the body portion 3030 are a pair of spaced downwardly extending legs 3042, 3044 defining a generally rectangularly shaped recess 3046 therebetween. The dependent ends of the legs 3042 and 3044 include inwardly facing cam follower lobes 3048 and 3050 respectively and adjacent flat cam follower surfaces 3052 and 3054, respectively. As best shown in Figures 38A and 40 mounted on the rotatable inner race 3070 of the sinker assembly support bearing 3018 is a sinker pot web support ring 3072 having the spaced outer webs 3074 of the sinker pot base 3076 secured thereto by screws 3075. The sinker pot base 3076 is suitably apertured, as at 3078, to permit passage of the compound needle elements therethrough. The inwardly disposed portion of the sinker pot base 3076A supports the spaced inner webs 3080 and is also splined to the knitting needle support cylinder 4042, as at 3081, to assure conjoint rotation of the sinker pot and the sinker elements in conjunction therewith. Referring now to Figures 38A and 40 the sinker elements 3026 are disposed within the slots 3079 intermediate the webs 3074 and 3080 and are supported by the engagement of the flat cam follower surfaces 3052 and 3054 on a pair of lower vertical control cam surfaces 3082 and 3084 disposed on either side of a recess 3086 on the upper surface of the body portion of the sinker assembly support plate 2092. Controlled vertical displacement of the sinker elements 3026 relative to the sinker pot 3076 is effected through the complemental compound contouring of vertical control cam surfaces 3082, 3084 and 3022 with the sinker elements 3026 always being confined top and bottom by cam control surfaces. Disposed within the recess 3086 in the sinker assembly support plate 3092 is a radial sinker positioning cam ring 3090. As shown on the left hand side of Figure 38A the radial sinker positioning cam ring 3090 is secured, as by bolts 3092, to an outwardly and upwardly extending boss 3094 on the upper locking channel ring 3096, and extends upwardly above the lower vertical cam control surfaces 3082 and 3084 on the upper surface of the sinker assembly support plate 2092. Such mounting fixes the elevation of the radial sinker positioning cam ring 3090 relative to the machine frame 2060 and renders the same independent of changes in elevation of the sinker assembly. The side walls of the radial sinker positioning cam ring 3090 serve as control cam surfaces engageable with the extending cam lobes 3048 and 3050 on the depending leg portions of the sinker elements 3026 to displace the sinkers radially and transverse to the direction of knitting needle advance. while the side walls of the sinker positioning cam ring 3090 are normally vertically disposed, as shown on the left hand side of Figure 38A, they are selectively skewed at predetermined distances on either side of each yarn feed location, as shown on the right hand side of Figures 38A, to provide for additional incremental transverse radial displacement at such locations. Such additional incremental transverse displacement compensates for variation in stitch length provided by elevation of the sinker assembly support plate 2092. COMPOUND KNITTING NEEDLE MEMBERS The structure and configuration of the needle and closing elements constituting the compound knitting needle members employed in the presently preferred machine construction described in Figure 37 and the following Figures are identical with those earlier described and depicted in Figures 9 and 12 except for one added particular and will not be herein entirely redescribed in detail. As best shown in Figures 44 and 45, which bear the same reference numerals as heretofore employed for the basic needle element structure, the elongate needle element 290 has added thereto an additional pair of rectangularly shaped cam butts 3100, 3102 extending from the marginal edges of the walls of the upper bifurcated portion 294 and thereby are disposed on either side of the elongate channel 296. In a similar manner, and as best shown in Figure 46, the elongate closing element 310 has added thereto an additional rectangularly shaped cam butt 3104 extending from the upper intermediate portion 324 thereof. The butt 3104 is located on the closing element in such manner as to be disposed between the butts 3100 and 3102 when the needle and closing elements are in the closed position in the vicinity of the selection points. COMPOUND NEEDLE ELEMENT SELECTION AND DISPLACEMENT SYSTEM The compound needle displacement and selection system employed in the presently preferred machine construction is essentially the same as these heretofore described in the parent application and will not be herein redescribed in detail. One modification has been introduced in the provision of an auxiliary means to preclude longitudinal displacement of both the needle and closing elements of each compound needle for a predetermined distance on either side of each selection point and to thereby positively lock the vertical positioning of the needle and closing elements during the selection process. A second modification introduced by the presently preferred construction lies in the provision of improved means for positively displacing the upper portion of the needle and closing elements relative to fulcrum point within their respective knitting needle support cylinder slots 82 to bias the lower portion of both the needle and closing elements inwardly throughout the selection zone. A third modification lies in the provision of an improved presser cam assembly to positively displace the lower portions of the flexible shank needle and closing elements toward the selection heads at the selection points. With respect to the first and second modifications and referring initially to Figures 38A and 41, there is provided a non-rotatable upper locking channel defining ring 3096 encircling the upper end of the knitting needle support cylinder 2042 and secured to the upper surface of the outer frame member 2060 by bolts 3110. Disposed immediately beneath the channel defining ring 3096 and vertically restrained thereby is a roller ring assembly 3112. The roller ring assembly 3112 is constituted by the upper portion of a cage ring 3114, a plurality of individually radially displaceable rollers 3116 and the lower portion of the cage ring 3114 supported by the ring ear 2044. Both the rollers 3116, the roller cage 3114, and the compression band 3122 are free to move circumferentially (not vertically) responsive to movement of the needles and the needle cylinder within the cam track 3120. The rollers 3116 ride against a needle element compression cam track 3120 formed by the selective contouring of a portion of the adjacent wall of the outer frame 2060. The needle element compression cam track 3120 operates to radially displace the rollers 3116 in the inward direction against a flexible needle member compression band 3122 that encircles the knitting needle support cylinder 2042 in such a manner as to deflect such band into compressive engagement with the adjacent exposed surfaces of both the needle elements and closing elements, as shown on the left hand side of Figure 38A, for a predetermined distance on either side of the selection points. The engagement of the compression band 3122 against the needle and closing elements in association with a slightly deepened needle guide slot 82 (see Figure 47) effects localized needle and closing element deflection relative fulcrum location 3108 and in a concommitant greater inwardly directed deflection of the lower ends of the needle and closing elements. The diametric extent of the inwardly facing surface 3124 of the upper channel defining ring 3096 is selectively contoured so as to overlie and thereby define, in association with the upper edge of the compression band 3122, a butt receiving channel segment 3126 at each of the selection zones as best shown on the left hand side of Figure 38A. As there shown, the channel segment 3126 is sized to receive and closely contain the extending butts 3100 and 3102 on the needle elements and the extending butts 3104 on the closing elements for a predetermined distance on either side of and through the selection point. The disposition of the butts 3100, 3102, and 3104 within the channel segments 3126 serves to positively lock both the needle and closing elements of each compound needle member at a predetermined elevation and precludes any vertical displacement thereof as the lower portions thereof approach and depart from each selection point. Such positive locking against vertical displacement at end near each of the selection points serves to positively ensure proper elevational positioning of the lower end cam butts 302, 304, 318, and 320 on the needle and closing elements relative to the various inner and outer cam tracks during the selection process as well as positively ensuring proper positioning of the magnetic containment pads 288 and 330 on the needle and closing elements respectively against the appropriate magnet surfaces during the selection process. Additionally such locking of the needle members serves to maintain the fully drawn stitch and precludes "robbing back" of yard into the stitches being formed by the immediately succeeding needles approaching the selection zone. As may now be apparent, the locking of the needle and closing elements against vertical displacement through disposition of the cam butts 3100, 3102, and 3104 within the channel segments 3126 occurs concurrently with the engagement and inward displacement of the needle and closing elements by the localized inwardly directed by displacement of the needle compression band 3122 by the rollers 3116. Such engagement and localized displacement effectively moves both the engaged needle and closing elements within deepened slots 82 and the knitting needle support cylinder 2042 and cooperates with an overlying fulcrum location 3108 against which the upper portion of the needles and closing elements can pivot to create the desired flexure and inwardly directed displacement of the lower portions thereof during the selection process, as heretofore described in the earlier portions of this specification. In contradistinction to the above described inward extensions of the upper channel defining ring 3096 to form the discrete butt receiving channel segments 3126 at the selection zones, the ring 3096 is further selectively contoured so as to discontinue such inwardly extending and overlying marginal edge portions 3124 at all locations other than the selection zones, so as to permit, as illustrated on the right hand side of Figure 38A and Figure 39, unimpeded vertical displacement of both the needle and closing elements therepast at such other locations to effect the selected knit, tuck, or float operations. Concurrently therewith, the needle element compression cam track 3120 allows an outwardly directed movement of the rollers 3116 at such locations and a consequent release of radial inwardly directed pressure on the needle compression band 3122. As generally noted above, the third modification included in the presently preferred construction for the circular weft knitting machines is a modified presser cam assembly at each of the selection zones. By way of general introduction, the presently preferred construction, as hereinafter described in greater detail, locates the preselection presser cam induced deflections of the cam butt bearing lower end portions of both the needle and closing elements in close proximity to the selection point to eliminate any possible needle member dead bands on either side of the selection point that might otherwise be attendant changes in direction of knitting cylinder rotation. As best shown on the left hand side in Figure 38A and in Figures 48 through 51, the inner cam track sleeve 2050 is vertically slotted at the selection zones, as at 3130, to accommodate the inclusion therein of two pairs of vertically disposed presser cams, the upper pair of which is generally designated 3132 and the lower pair of which is generally designated 3136. Disposed within the non-rotating inner cam track sleeve 2050 and serving as one of the defining walls of each of said slots 3130 is a non-rotatable but vertically displaceable presser cam sleeve member 3134. The upper presser cam assembly pair 3132 includes upper side by side presser cams 3140 and 3142 for effecting positive deflection, as at 3138 in Figure 50, of the lower ends of the closing elements. The lower presser cam assembly pair 3136 includes lower side by side presser cams 3144 and 3146 for effecting positive deflection, as at 3139 on Figure 51, of the lower ends of the needle elements. Referring now to Figures 38A and Figures 49-51 and utilizing the upper pair of upper side by side presser cams 3140 and 3142 as exemplary, and with the further understanding that presser cams 3140 and 3142 are mirror images of each other, each presser cam includes a pair of terminally located cam follower lobes 3170 and 3172 extending inwardly of the inner surface thereof. Each presser cam in the pair thereof is mounted on and adapted to be individually and independently rotatably displaced about a common pivot axis 3174. The upwardly extending end portion 3176 of each presser cam in the upper pair 3132 thereof is longitudinally slotted, as at 3178, to form a pair of bifurcated elongate resilient arms 3180 and 3182 with the arms 3180 having the cam follower lobe 3170 on the terminal end of the inner facing surface thereof. The bifurcated character of the upper portion thereof renders the arms 3180 and 3182 somewhat resilient and such resilience functions to accomodate varying tolerances and wear of the machine components and affords an extended operating life to the presser cams. Mounted at the end of the outwardly facing surfaces of the arm 3182 of each cam 3140 and 3042 in the upper pair 3132 thereof is a selectively contoured cam surface 3178 adapted to engage and deflect the extending butts at the bottom ends of the closing elements. As is apparent from Figure 50, presser cam 3142 is of similar configuration to that of presser cam 3140 except that the contoured cam surface 3184 thereon is a mirror image of cam surface 3178 to accommodate bidirectional knitting cylinder displacement. As is apparent from the drawings, the lower pair 3136 of side by side presser cams 3144 and 3146 are of identical construction a that described above the the upper pair 3132 of presser cams 3140 and 3142. Referring now to Figures 38A, 38B and 49, the presser cam sleeve member 3134 includes a first conjugate pair of presser cam member shifting cams 3190A and 3190B and 3192A and 3192B and a second identical pair of conjugate presser cam shifting cams for the lower pair of presser cams 3136. Such shifting cams effect pivotal displacement of the associated presser cam when the presser cam sleeve member 3134 is vertically reciprocated intermediate an upper and a lower position. Such vertical reciprocation is effected by solenoids 3198 and 3200 located at the lower end of the sleeve member 3134 as shown in Figure 38B. As will be apparent, when the presser cam sleeve member 3134 is moved to its upper position, the shifting cam 3190A will engage cam lobe 3170 to relate presser cam 3140 and cause contoured presser cam face 3178 to move into engagement with the closing element butts to effect positive displacement thereof. Simultaneously, however, the adjacent presser cam 3142 mounted on common pivot 3174 will be retracted disengaging contoured cam face 3184 from engagement with the closing element butts. When the presser cam sleeve 3134 is in its lower position as shown in Figure 49, the contoured cam face 3184 of presser cam 3142 is in its advanced position to engage the closing element butts due to engagement of shifting cam lobe 3192A with accompanying displacement of the cam follower lobe 3191. As will now be equally apparent, a similar mode of operation is simultaneously effected for the lower pair of presser cams 3136 which engage the needle element butts. LASER YARN CUTTING SYSTEM Conventional knitting machines employ mechanical shearing mechanisms of either the rotating saw or scissor types to effect yarn cutting. Such mechanical shearing mechanisms are highly subject to wear with an attendant limited and unpredictable useful operating life. In order to alleviate this problem, the presently preferred construction includes a laser beam yarn cutting assembly adapted to effect the severing of a yarn fiber in 2 to 8 milliseconds. Referring to Figures 37 and 53 such assembly includes a 6 to 10 watt confined gas CO₂ laser 1928 located in the cabinet 1902. Such type lasers are of conventional construction and are available from Laakmann Electro-Optics, Inc. of San Juan Capistrano, California. The laser beam 3500 is directed upward through the supporting standard 1918 and a conduit section attending therefore 1930a. The beam 3500 is reflected by a mirror 1932 through horizontal conduit section 1930b and reflected by a second mirror 1934 downwardly through conduit section 1930c on the longitudinal axis 1904. Mounted below and suspended from the dial assembly 1924 is a third mirror 3502 mounted on the shaft 3504 of a positioning motor 3506 which includes an integral resolver 3508. The mirror 3502 is inclined at a predetermined angle to axis 1904 to direct the light beam 3500 to a particular location above the highest point of needle travel and therefore a circular ring transversed by the beam reflected from the rotating mirror defines a yarn cutting zone. This yarn cutting zone is effectively divided in operative yarn severing sections by modulating the laser 1928 between on and off status. Auxiliary means are provided to elevate the yarn after programmed engagement with the last needle into the cutting zone and into the path of the light beam 3500. Such auxiliary means also guide and transport the yarn located in the cutting zone in a circumferential path and at the same speed as the cylinder advance. This permits the rotating laser beam 3500 to be synchronized with a particular spot on the moving yarn fiber for sufficient time to vaporize and thus sever the yarn fiber. SYSTEM CONTROL The mechanical and electromechanical components of the circular weft knitting machine described herein can be sized in a variety of ways to particularly and economically satisfy specific knitting requirements associated with large numbers of different yarns and sock styles. For example, in some situations a five inch pitch diameter knitting cylinder having no more than 60 needles will be needed to knit ski socks with heavy yarn. In contradistinction thereto, the knitting of fine denier fancy dress socks falls at the other end of the spectrum and will require 240 needles mounted on a knitting cylinder with a 3½ inch pitch diameter. Similarly, depending upon the particular sock styling requirements, a machine may need as few as four selection heads and four yarn feeds or it may need to have as many as eight separate yarn feeds and an equal number of selection heads. The accommodation of such variation in both knitting machine components and in sock styling poses problems of serious magnitude in controlling the operation thereof in an efficient and economical manner. In fact the accommodations of such variation in sock styling and machine components far exceed the capacity of a simple microprocessor or control system. The hereinafter described and presently preferred knitting machine control system is adapted to implement a particular mode or method of handling and controlling the flow of information on a real time basis and is of such character as to allow for use of a single programming compiler and the same basic computer hardware for handling digital information for all combinations of needle counts, yarn feeds and sock styles. In contradistinction to conventional knitting machines, machines incorporating the principles of this invention attain substantial increases in production and programming flexibility by rapidly accelerating and decelerating the rotation of the knitting cylinder and the knitting elements associated therewith. Since the machines herein disclosed employ angular accelerations in the order of four to eight thousand radians per second² in comparison to accelerations in the order of 50 to 100 radians per second² in conventional knitting machines, a modular displacement responsive operating control system based upon the precise position and velocity of the knitting cylinder at all times during displacement is herein disclosed. Included in such system is the utilization of a modular architecture which affords separation of function, synchronization of action and modular software independence. Fundamental to the operation of the hereinafter described system are the following steps in the handling and flow of digital data for fabrication of a particular article on a particular machine: (a) introducing digital data indicative of a monotonically increasing (never decreasing) schedule of instruction steps for fabrication of said article on to a special communication bus; (b) introducing digital data indicative of the instantaneous position and velocity of a knitting needle support cylinder having a multiplicity of stitch forming elements mounted herein on to said special communication bus; (c) controlling the operation of said stitch forming elements to knit, tuck, or float in accord with a first set of selectively generated commands responsive to the composite digital data on said special communications bus and a first set of stored instructions uniquely relating to fabrication of said article; (d) controlling the engagement of yarns by said stitch forming elements in accord with a second set of selectively generated commands responsive to the composite digital data on said special communication bus and a second set of stored instructions uniquely relating to the fabrication of said article; (e) controlling the displacement and velocity of said knitting needle support cylinder in accord with a third set of selectively generated commands responsive to said instruction step digital data on said special communication bus and a third set of stored instructions uniquely relating to the fabrication of said article; (f) selectively releasing the individual steps of said monotonically increasing schedule of instruction steps in response to the presence of said knitting cylinder position information on said special communication bus and a fourth set of stored instructions uniquely relating to the fabrication of said article. Because the knitting machine control system must be synchronized accurately with the relative positions of the rotating elements therein, such as sinkers and needles, the system includes a special communication bus from which all the microprocessors located in the control modules involved in the machine control system can reference and time synchronize their various functions and so operate on a real time basis. Referring to Figure 52, the special communication bus 3800, which is in the nature of a 48 line read only parallel data bus, herein called the K-bus, communicates with a Servo Motor Control Module 3802, one or more auxiliary function control modules 3804, one or more needle control modules 3806, one or more yarn control modules 3808 and a machine manager module 3810. Each of these control modules is also connected to a VME-bus 3814 which is bidirectional asynchronous bus used for general transfer of information and communication among the modules. The Servo Motor Control Module 3802 includes a special interface 3812 designated as a K-module, which contains a one megabyte dual port RAM, two high speed hardware comparators, a VME bus master interface and a generic microprocessor logic interface, all of which are of standard construction and which will not be further described or shown herein. Also included in the Servo Motor Control Module 3802 is a microprocessor, suitably an Intel 80186, a driver for the K-bus 3800 to write out instantaneous position and velocity integers for the knitting cylinder, a general purpose motion control integrated circuit, suitably a Hewlett Packard HCTL-1000, a rotary to digital converter and suitable I/O circuits for communicating with the motor amplifier 3186, resolver 3188 and main drive motor 2020. The Auxiliary Function Control Module 3804 includes a K-module interface 3812, having the same components as described above. All included in the auxiliary function control module 3804 is a microprocessor, again suitably an Intel 80186, optical isolators, stepping motor controls, suitably Cybernetic Micro Systems CY512's, serial MUX communication system and parallel I/O ports. Among the functions controlled by this module 3804 are shifting of the presser cam actuating sleeve 3134, positioning of the yarn cutting means, length of stitch control through control of sector gear 3008 by a stepping motor (not shown), terry cam phasing, vacuum take down control, and the line. The Needle Control Module 3806 includes a standard K-module 3812 as described above. Also included are a microprocessor, again suitably an Intel 80186, digital to analog converters for establishing current pulse values, and suitable I/O circuits to interface with the bipolar selection head drive circuits. The function controlled by this module 3806 is the setting of pulse delay, pulse width and pulse height for the timed actuation of each needle selection operation and thus controlling the operation to be performed by each needle, i.e. knitting, tucking, or floating. The Yarn Control Module 3808 includes a standard K-module 3812, as described above. Also included are a microprocessor, suitably an Intel 80186, additional RAM memory, I/O drivers for bipolar operation of voice coil yarn positioners, yarn tension controls, yarn binding controls, electrostatic yarn usage detectors, yarn break detectors and the like. The functions performed by this control module and its associated actuators are generally those attendant yarn selection and yarn feeding, stitch length measurement and yarn comsumption logging. The Machine Manager Module 3810 includes a standard K-module 3812 as described above. Also included therein is a microprocessor, suitably here an Intel 80286, and a driver for the K-bus 3800 to write out the monotonically increasing schedule of instruction for the fabrication of the particular article being made. Such schedule of instruction data, in the form of integers will hereinafter be termed "Sock Status Number." As will now be apparent, the employment of a standard K-module 3812 in each of the major control modules establishes a system architecture which allows modification of any individual control module hardware or software without requiring changes in the programming or hardware of the remaining modules. It also facilitates future expansion of the system to accomodate, for example, dual cylinder knitting machines, without modifying the existing control system and simplifies system maintenance. The Sock Status Number information stream issued by the Machine Manager Module 3810 and the knitting cylinder position and velocity information stream issued by the Motor Servo Control Module 3802 for all the modules are introduced to and carried on the K-bus 3800 in parallel form and include 24 bits of sock status information, 8 bits of velocity information and 16 bits of cylinder position information. In addition to a standardization of the electronic hardware associated with this system, the described system architecture also permits an improved overall functional mode of operation which includes the following basic operational modes for all knitting machine functions. The first pre-operational mode is a "Power Up" mode. When an individual knitting machine is first turned on, each of the above described control modules is adapted to conduct an internal testing of its own circuits and those of its associated I/O devices in order to determine whether the knitting machine is ready to function. For example, the Needle Control Module 3806 will test each of its selection head drivers to see that there are no open circuits in the coils or malfunctions in the coil driving amplifiers. Each module then records a "Ready to Run" status message at a predetermined location in its K-module dual port RAM in such manner that the Machine Manager Module 3810 can poll each of the control modules in a given sequence to determine that all are ready for continued operation. The next pre-operational mode is the Initialization Mode. In this pre-operational mode, the Machine Manager Module 3810 obtains, either directly from a bus extension computer 3830, or through the "communication" module 3832, elsewhere stored pre-compiled instructions for all of the memory units necessary to produce a desired sock style. The Machine Manager Module 3810 passes a portion of these instructions on to each of the other operating modules in a given knitting machine through the VME-bus 3814. After checking to see that all the instructions so passed on are ready for use in each operating module, the Machine Manager Module 3810 shifts from the Initialization Mode to the Run Mode. In the Run Mode the Machine Manager Module 3810 initiates actions by writing out a new Sock Status Number on to the K-bus 3800 where such Sock Status Number is read by the K-module comparator in each of the operating control modules 3802, 3804, 3806, and 3808. The Sock Status Numbers, and the sequence thereof, for the article being made are stored in the Machine Manager Module 3810 during the Initialization Mode. Such Sock Status Numbers originate in an external compiler, not shown, and consist of monotonically increasing integers which represent the cumulative absolute value of the amount of knitting cylinder rotation at any given instant of time in the fabrication of a particular article. Such cumulative absolute value of the amount of knitting cylinder rotation serves as the real time base for system operation in association with supplemental integers inserted by the compiler to initiate actions when the knitting cylinder is at rest at any point in the operational cycle as, for example, when the knitting cylinder reverses its direction of rotation. Sock Status Numbers for the article to be manufactured, which originate in the compiler, are stored in the factory production computer 3834 and are transferred to the Machine Manager Module 3810 through a Communication Module 3832 over a high speed serial network 3836 conforming to MAP standards. For example, each time the knitting needle support cylinder 2042 is rotated by the drive motor, for example, 1/512th of a revolution in either direction, the value of the Sock Status Number is positively incremented by one. So also if the knitting cylinder is brought to rest in anticipation of reversing its direction of rotation, the presser cams must be shifter prior to the start of the next movement of the knitting cylinder; therefore, the Machine Manager Module 3810 will read the K-bus velocity and position signals emanating from the Motor Servo Control Module 3802 to determine that the knitting cylinder was actually at rest. After doing so, the Manager Module 3810 will positively increment the Sock Status Number, even though there was no movement of the cylinder, in order to tell the Auxiliary Function Control Module 3804 that it was now safe to shift the presser cams. After receiving a communication through the VME-bus from the Auxiliary Function Control Module that the presser cams had been fully shifted, the Machine Manager Module will again increment the Sock Status Number so as to tell the Motor Servo Control Module that the system was now ready for the next planned movement of the knitting cylinder. Over-travel distances caused by servo system errors are not permitted to cause the value of the Sock Status Number to increase. In those instances that require a precise synchronization of the needle selection heads with the knitting cylinder position, the Machine Manager Module 3810 will, in advance of the time that such a command is to be executed, positively increment the Sock Status Number. The sock status comparator in the K-module portion of the Needle Control Module 3806 is continuously monitoring the K-bus 3800 looking for the presence of the particular Sock Status Number which indicates that the time is nearing for its next needle command. When the Sock Status Number comparator sees a valid Sock Status Number check, it retrieves from its own memory the Sock Status Number for the next action and loads it in the K-module comparator. Coincidentally therewith, the cylinder position at which the current needle selection is to take place is returned from memory, along with the instruction for the current needle selection action to be taken. Such instructions contain the particular combination of knit, tuck, and float commands to be executed at each feed. In order to accommodate a wide range of cylinder operating speeds, the timing of the application of the information retrieved from the memory to the selection heads must be modified in accord therewith. To such end, the Needle Control Module microprocessor reads the current knitting cylinder velocity information from the K-bus 3800 and adjusts the timing delay between the valid position comparison signal and the leading edge of the current pulse to the selection head according to the velocity value stored in a look up table in the module memory. In the same manner the amplitude and duration of the selection head pulse is adjusted in accord with knitting cylinder speed. The operation of the Auxiliary Function Control Module 3807 and Yarn Control Module 3808 are essentially of the same character during the Run Mode as that described above. That is, a first comparison is made with the Sock Status Number of the K-bus 3800 by the K-module comparator to determine what action is to be taken. Thereafter, upon valid comparison, instructions are returned from module memory and are executed in accordance with cylinder position comparison and velocity modification thereof. The cylinder position signal emanating from the Motor Servo Control module 3802 is upgraded on the K-bus 3800 more frequently than is the Sock Status Number emanating from the Machine Manager Module 3810. The cylinder position signal is accurate to 1/4096th of a revolution or approximately 1/10 of a degree. Such position information values are updated over and over again as the cylinder rotates and give the actual angular position of the knitting cylinder from a predetermined mechanical zero point associated with the machine. As described above, in conjunction with the operation of the Needle Control Module 3812, after the reading out of the function data and the desired action position from the internal module memory, each operating module compares the knitting cylinder angular position data on the K-bus 3800 with a position value retrieved from memory until a positive match is obtained, at which time the desired action is initiated. As also indicated above, each control module may delay the timing of the action to be taken, in accordance with current cylinder velocity. In this way each operating module can function individually and independent of the Machine Manager Module in the Run Mode to effect its own sequential execution of a list of required actions necessary to form a sock while still remaining synchronized with the actions of all other modules and the mechanical functioning of the system. In the normal Run Mode of operation, minimal amounts of information are passed over the VME-bus 3814 rendering such bus available as an auxiliary communication channel to transmit information concerning possible system faults such as yarn breaks, electronic malfunction, motor overheating and the like. When a fault occurs, each of the operation control modules is programmed to issue a descriptive fault signal which is posted in the dual port RAM in the K-module 3812 thereof. The Machine Manager Module 3810, using the VME-bus 3814, polls each of the dual port RAMS for such signal. If a signal is sensed, the Machine Manager Module 3810, through an internal look up table, retrieves and initiates an appropriate error service routine.

Claims: A method for the operational control, by means of a microprocessor, of a circular weft knitting machine that includes a rotatable knitting needle support cylinder (2042) having a multiplicity of stitch forming elements (2049) mounted thereon to knit an article of particular character, the method including the steps of: (a) introducing digital data at separated intervals indicative of a monotonically increasing schedule of instruction steps for fabrication of said particular article on to a special communication bus (3800); and (b) continuously introducing digital data indicative of the current position and velocity of the knitting needle support cylinder (2042) on to said special communication bus (3800); characterised by: (c) controlling the operation of said stitch forming elements (2049) to knit, tuck, or float in accord with a first set of locally generated selective commands responsive to the composite digital data on said special communication bus (3800) and a first set of stored instructions uniquely relating to the fabrication of said particular article; (d) controlling the engagement of yarns by said stitch forming elements (2049) in accord with a second set of locally generated selective commands responsive to the composite digital data on said special communication bus (3800) and a second set of stored instructions uniquely relating to the fabrication of said particular article; (e) controlling the displacement and velocity of said knitting needle support cylinder (2042) in accord with a third set of locally generated selective commands responsive to said instruction step digital data present on said special communication bus (3800) and a third set of stored instructions uniquely relating to the fabrication of said particular article; and (f) selectively releasing the individual steps of said monotonically increasing schedule of instruction steps in response to the presence of said knitting cylinder position information on said special communication bus (3800) and a fourth set of stored instructions uniquely relating to the fabrication of said particular article. The operational control method as claimed in claim 1, including the further step of introducing said first, second, third and fourth set of instructions uniquely relating to the fabrication of said particular article into the knitting machine memory components from a remote source thereof through a separate bidirectional general communication bus (3814) prior to the initiation of operation to fabricate said particular article. The operational control method as claimed in claim 1 or 2, including the further step of scanning the machine components for an internally generated fault signal indicative of a component malfunction intermediate the introduction of each of said separated instruction steps on to said special communication bus (3800). The operational control method as claimed in claim 3, including the further step of instituting a fault correction routine that must be satisfied before the introduction of each instruction step on to said special communication bus (3800). A microprocessor-controlled operational control system for a high speed circular weft knitting machine of the type that includes a rotatable knitting needle support cylinder (2042) having a multiplicity of stitch forming elements (2049) mounted thereon to knit an article of particular character, said system operating responsive to the precise position and velocity of said support cylinder (2042), said system further including: (a) a multi-line communication bus (3800); (b) machine managing module means (3810) for introducing digital data at separated intervals indicative of a monotonically increasing schedule of instruction steps for fabrication of said particular article on to said communication bus (3800); and (c) motor control module means (3802) for continuously introducing digital data indicative of the current position and velocity of the knitting needle support cylinder (2042) on to said communication bus (3800); (d) said machine managing module means (3810) further releasing the individual steps of said monotonically increasing schedule of instruction steps in response to the presence of said knitting cylinder position information on said communication bus (3800) and a fourth set of stored instructions uniquely relating to the fabrication of said particular article; characterised by: (e) needle control module means (3806) for controlling the operation of said stitch forming elements (2049) to knit, tuck or float in accord with a first set of locally generated selective commands responsive to the composite digital data on said communication bus (3800) and a first set of stored instructions uniquely relating to the fabrication of said particular article ; and (f) yarn control module means (3808) for controlling the engagement of yarns by said stitch forming elements (2049) in accord with a second set of locally generated selective commands responsive to the composite digital data on said special communication bus (3800) and a second set of stored instructions uniquely relating to the fabrication of said particular article; (g) said motor control module means (3802) further controlling the displacement and velocity of said knitting needle support cylinder (2042) in accord with a third set of locally generated selective commands responsive to said instruction step digital data present on said multi-line communication bus (3800) and a third set of stored instructions uniquely relating to the fabrication of said particular article. The control system as claimed in claim 5, including means introducing said set of instructions uniquely relating to the fabrication of said particular article into the knitting machine memory components from a remote source thereof through a separate bidirectional general communication bus (3814) prior to the initiation of operation to fabricate said particular article. The control system as claimed in claim 5, 6, wherein said machine managing module means (3810) institutes a fault correction routine that must be satisfied before the introduction of each instruction step on to said communication bus (3800).

Inventors: TIBBALS EDWARD CAMP JR, TIBBALS, EDWARD CAMP, JR.
Applicants: DRAPER CORP, DRAPER CORPORATION
Application year: 1987
Main classification: D04B15
IPC codes: D04B15, D04B35, D04B9