Abstract:
A glass machine system in accordance with presently preferred embodiments of the invention includes a glassware manufacturing machine for manufacturing articles of glassware and transferring the articles to a linear conveyor, at least one linear chain conveyor for receiving and transporting such articles from the machine, and a speed sensor for monitoring linear speed of the conveyor. The speed sensor includes a magnetic energy source, a magnetic energy sensor and bracketry mounting the source and sensor adjacent to the conveyor. The chain conveyor teeth affect magnetic energy coupling between the source and sensor as the conveyor passes adjacent to the sensor. Electronic circuitry is responsive to signals from the sensor for determining linear speed of the conveyor and maintaining a constant linear speed at the conveyor.

Description:
The present invention is directed to transport of glassware on a linear conveyor from a glassware manufacturing machine to an annealing lehr or other post-manufacturing stage, and more particularly to monitoring speed of the linear conveyor. 
     BACKGROUND AND OBJECTS OF THE INVENTION 
     The science of glass container manufacture is currently served by the so-called individual section machine. Such a machine has a plurality of separate or individual manufacturing sections, each of which has a multiplicity of operating mechanisms for converting one or more charges or gobs of molten glass into hollow glass containers and transferring the containers through successive stations of the machine section. Each machine section includes one or more blank molds in which a glass gob is initially formed in a pressing or blowing operation, an invert arm for transferring the blanks to blow molds in which the containers are blown to final form, tongs for removing the formed containers onto a deadplate, and a sweepout mechanism for transferring molded containers from the deadplate onto a conveyor. U.S. Pat. No. 4,362,544 includes a background discussion of both blow-and-blow and press-and-blow glassware forming processes, and discloses an electropneumatic individual section machine adapted for use in either process. 
     As shown in U.S. Pat. No. 4,193,784, the individual machine sections operate in synchronism but out of phase with each other to form the glass containers and place the containers in sequence onto a linear machine conveyor. Containers on the linear machine conveyor are transferred to a linear cross conveyor, from which the containers are loaded into an annealing lehr. The sweepout stations of the individual machine sections are timed to transfer the finished containers to the machine conveyor such that the containers are in spaced groups, within which the containers are at uniform spacing from each other. Each group is transferred simultaneously to the annealing lehr. It is important to maintain a constant speed at the linear conveyors so that the containers will be at uniform spacing within each group, and the groups will be at uniform spacing with respect to each other, when they arrive at the lehr loader mechanism. U.S. Pat. No. 6,076,654 discloses a glass container handling system in which the linear machine conveyor and the linear cross conveyor are driven by associated electric motors coupled to a motor controller. A speed sensor is associated with each conveyor for providing an electrical signal to the controller indicative of conveyor speed. The control electronics controls operation of the motors to maintain the desired constant speed at each conveyor. 
     It is an object of the present invention to provide a glass machine system having sensors for sensing linear speed of the machine and/or cross conveyor, in which the sensor is constructed and arranged to accommodate wear at the conveyor while providing an accurate and reliable measure of conveyor speed. 
     SUMMARY OF THE INVENTION 
     A glass machine system in accordance with presently preferred embodiments of the invention includes a glassware manufacturing machine for manufacturing articles of glassware and transferring the articles to a linear conveyor, at-least one linear conveyor for receiving and transporting such articles from the machine, and a speed sensor for monitoring linear speed of the conveyor. The speed sensor includes a magnetic energy source, a magnetic energy sensor, and bracketry mounting the source and sensor adjacent to the conveyor. The conveyor affects magnetic energy coupling between the source and sensor as the conveyor passes adjacent to the sensor. Electronic circuitry is responsive to signals from the sensor for determining linear speed of the conveyor. The conveyor preferably takes the form of a chain conveyor having teeth along an undersurface for engaging a motor-driven pulley to drive the conveyor. The teeth are magnetically permeable, and passage of the teeth affects magnetic coupling between the energy source and energy sensor of the speed sensor. The control electronics preferably is coupled to the pulley drive motor for maintaining constant linear speed at the conveyor. 
     The conveyor speed sensor in the preferred embodiments of the invention includes a floating subassembly having at least one a roller for engaging an upper surface of the conveyor. The magnetic energy source and sensor are carried by the floating subassembly and disposed beneath the conveyor. In this way, constant spacing is maintained between the conveyor undersurface and the magnetic source/sensor arrangement against changes in vertical position of the conveyor due to wear of a plate over which the conveyor slides. The floating subassembly is slidable on rods carried in fixed position adjacent to the conveyor, and coil springs bias the roller(s) on the subassembly into engagement with the upper surface of the conveyor. The magnetic energy sensor in the preferred embodiments of the invention comprises a Hall sensor, although other conventional types of magnetic energy sensors may readily be employed. The magnetic energy source in the preferred embodiments of the invention comprises a permanent magnet or an electromagnet coupled to the electronic circuitry. A magnetic energy concentrator preferably is associated with the source and the sensor for concentrating passage of magnetic energy through the sensor to enhance responsiveness of the sensor to passage of conveyor drive teeth. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The invention, together with additional objects, features and advantages thereof, will be best understood from the following description, the appended claims and the accompanying drawings in which: 
     FIG. 1 is a schematic diagram of a glass manufacturing system in accordance with a presently preferred implementation of the invention; 
     FIG. 2 is a side elevational view of a conveyor speed sensor in the system of FIG. 1; 
     FIG. 3 is a partially sectioned end elevational view of the conveyor speed sensor illustrated in FIG. 2; 
     FIG. 4 is a top plan view of the sensor illustrated in FIGS. 2 and 3; 
     FIG. 5 is a partially sectioned elevational view of a portion of the speed sensor illustrated in FIGS. 2-4; 
     FIG. 6 is an electrical schematic diagram of the speed sensors and conveyor motor control electronics in the system of FIG. 1; 
     FIG. 7 is a partially sectioned elevational view similar to that of FIG. 5 but illustrating a modified speed sensor in accordance with the present invention; 
     FIG. 8 is an enlarged view of a portion of FIG. 7; 
     FIG. 9 is a bottom plan view of the portion of the sensor illustrated in FIG. 8; and 
     FIG. 10 is an electrical schematic diagram of a glass machine system embodying the speed sensor illustrated in FIGS.  7 - 8 . 
    
    
     DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS 
     The disclosures of above-noted U.S. Pat. Nos. 4,193,784 and 6,076,654 are incorporated herein by reference for purposes of background. 
     FIG. 1 illustrates a glassware manufacturing system  20  as comprising an individual section machine  22  having a plurality of sections  22   a-   22   h . Sections  22   a-   22   h  are generally identical to each other, and are operated in synchronism but out of phase with each other to convert gobs of molten glass into articles  24  of glassware, such as glass containers. Each machine section includes a sweepout station  26  at which the completed articles of glassware are transferred to a linear machine conveyor  28 . The glassware is transported by conveyor  28  to a transfer device  30 , at which the containers are transferred to a linear cross conveyor  32 . Cross conveyor  32  transports the containers to a position adjacent to a lehr loader  34 , which transfers the containers in groups onto the conveyor  36  of an annealing lehr  38 . The sequence of operation of sweepout stations  24  is coordinated with conveyor speed, etc. so that the glassware articles  24  are transported in groups by conveyors  28 ,  32 . The containers are preferably at uniform spacing within each group, and the groups are at a desired spacing with respect to each other. This spacing is such that the containers of each group may be loaded simultaneously by lehr loader  34  onto lehr conveyor  36 , and the lehr loader bar has sufficient time to retract before the next group of containers is in position at the loader. Machine conveyor  28  is driven by an electric motor  40  and a drive pulley  42 . Likewise, cross conveyor  32  is driven by an electric motor  44  and a drive pulley  46 . A conveyor speed sensor  48  is positioned adjacent to conveyor  28  for sensing linear speed of the conveyor, and a conveyor speed sensor  50  is positioned adjacent to conveyor  32  for sensing speed of operation of that conveyor. Speed sensors  48 ,  50  provide respective inputs to an electronic controller  52 , which is connected to motors  40 ,  44  for controlling speed of operation of the motors so as to obtain a desired substantially constant linear velocity at the respective conveyors. 
     FIGS. 2-5 illustrate the construction of speed sensor  48  associated with machine conveyor  28 . It will be understood, however, that speed sensor  50  associated with cross conveyor  32  is preferably identical to speed sensor  48 . Referring to FIGS. 2-4, machine conveyor  28  preferably comprises a chain-type conveyor having a plurality of pivotally interconnected links  54 . Links  54  are of magnetically permeable construction, such as steel. It will be understood, however, the invention may be employed in conjunction with other types of conveyors with magnetically permeable teeth, such as drive belts having strengthening metal inserts. Each link  54  has a pair of teeth that laterally align in assembly with the teeth of laterally adjacent links. These teeth engage the teeth of drive pulley  42  coupled to motor  40  (FIG. 1) to drive the conveyor. The conveyor is an endless conveyor, being trained around an idler pulley  56  (FIG. 1) at the opposing end of the conveyor. The upper reach of the conveyor slides along a wear plate  58  for supporting the weight of the conveyor and the articles of glassware carried by the conveyor. Friction between the undersurface of chain links  54  and the upper surface of plate  58  can cause wear of the plate, altering the vertical position of the conveyor. Wear of the chain link teeth and/or the pulley teeth also changes the effective radius of drive pulley  42 , which in turn changes the linear speed of the conveyor given a constant input from motor  40 . Speed sensor  48  in accordance with the present invention accommodates change in vertical position of conveyor  28  due to wear at plate  58  and/or the undersurface of conveyor  28 , and provides a measure of conveyor linear speed to control electronics  58  so that the electronics can control operation of motor  40  to maintain a constant linear velocity at the conveyor. 
     Speed sensor  48  includes a first fixed subassembly  57  and a second subassembly  59  that floats on subassembly  57 . Fixed subassembly  57  has a base  60  for mounting on a fixed support  62  adjacent to an edge of conveyor  28 . A pair of slides  64 ,  66  are secured to base  60  by screws  68  (FIG. 2) and extend upwardly adjacent to the edge of conveyor  28 . Slides  64 ,  66  are parallel to each other, and are longitudinally spaced with respect to each other in the direction of movement of conveyor  28 , as best seen in FIG. 3. A first bracket subassembly  70  includes a plate  72  having a pair of spaced linear bearings  74 ,  76  that slidably embrace slides  64 ,  66  respectively. An arm  78  is cantilevered to extend outwardly from plate  72  over the edge of conveyor  28 . A roller  80  is freely rotatably mounted on the end of arm  78  remote from plate  72  and extends downwardly from the lower edge of arm  78 , as best seen in FIG. 2. A pair of coil springs  82 ,  84  are captured in compression between bearings  74 ,  76  and caps  86 ,  88  secured to the upper ends of slides  64 ,  66  respectively. Thus, springs  82 ,  84  urge bracket subassembly  70  downwardly with respect to slides  64 ,  66  and base  60  to bring the periphery of roller  80  into rolling engagement with the upper surface of conveyor  28 . 
     A second bracket subassembly  90  includes an L-shaped arm  94  affixed to and suspended from plate  72  of first bracket subassembly  70 . An electromagnetic assembly  92  is mounted on the end of arm  94  so as to be positioned beneath the upper reach of conveyor  28 . Electromagnetic assembly  92  includes a permanent magnet  96  disposed between an axially aligned pair of ferromagnetic flux concentrator plugs  98 ,  100 . At least one Hall effect sensor  102 , and preferably a pair of Hall effect sensors  102 ,  103  are disposed adjacent to the tapering upper end of plug  98  beneath conveyor  28 . As best seen in FIG. 4, Hall sensors are at fixed spacing with respect to each other in the direction of motion of linear conveyor  28 . Magnet  96 , concentrator plugs  98 ,  100  and Hall effect sensors  102 ,  103  are mounted within a protective housing of insulator blocks  104 ,  106 ,  108 . Electrical wires  110  extend from sensors  102 ,  103  through a conduit  112  on arm  94 , and thence to an electrical connector  114  for connection to motor controller  118  (FIG.  6 ). Thus, the entire bracket assembly  59  that includes subassemblies  70 ,  90  “floats” with respect to base  60  at conveyor  28  for following vertical movement of the conveyor, due to wear at plate  58  or otherwise, while maintaining constant spacing between electromagnetic assembly  92  (and Hall sensors  102 ,  103 ) beneath the teeth of conveyor links  54 . 
     As illustrated in FIG. 6, Hall sensors  102 ,  103  of speed sensor  48  associated with machine conveyor  28  are connected within controller  52  through a signal conditioning circuit  116  to a motor controller  118 . Likewise, sensors  102 ,  103  of speed sensor  50  associated with cross conveyor  32  are connected through a signal conditioning circuit  120  to motor controller  118 . Passage of the chain conveyor teeth above sensors  102 ,  103  causes an increase in the intensity of magnetic energy conveyed through the sensors, so that the Hall sensors provide periodic outputs to the associated signal conditioning electronics and motor controller  118  at frequencies determined by the velocity of passage of the chain link teeth above the sensors. Within signal conditioning circuits  116 ,  120 , the sinusoidal signals from the sensors are fed through analog peak detectors to produce square wave signals that indicate when the edge of a tooth passes the respective sensors. Since the distance between the sensors is fixed and known, the velocity of the conveyor can be readily determined. Motor controller  118  is responsive to such signals for determining linear velocity at each conveyor, and controlling the speed of operation of the associated motor  40  or  44  to maintain a desired substantially constant velocity at each conveyor. Motors  40 ,  44  may be of any suitable type, as described in above-referenced U.S. Pat. No. 6,076,654. An air passage  122  (FIG. 2) extends through arm  78  of speed sensor  48  (and speed sensor  50 ). Air passage  122  terminates in a fitting  123  (FIG. 4) disposed between bearings  74 ,  76 . A valve  124  is responsive to controller  118  for periodically directing air through the links of conveyor  28  (and  32 ) to blow off any magnetic particles that may have accumulated on the upper surface of insulator block due to magnetic attraction to magnet  96 . 
     FIGS. 7-10 illustrate a modified speed sensor and motor control electronics in accordance with the present invention. Reference numerals identical to those in FIGS. 1-6 indicate identical components, and related components are indicated by identical reference numerals followed by the suffix “a.” FIGS. 7-8 illustrate a modified second bracket subassembly  90   a  as including a lower electromagnetic assembly  130  carried by arm  94 , and an upper electromagnetic assembly  132  carried by a cantilevered L-shaped arm  134 . Upper assembly  132  includes an electrical coil  136  and a ferromagnetic pole piece  138  that together form an electromagnetic for directing magnetic energy through conveyor  28  to assembly  130 . Coil  136  has a pair of leads  140  that extend through a conduit  142  to an electrical connector  114   a . Assembly  130  (FIGS. 7-9) includes a second coil  146  and a pole piece  148  that form a second electromagnet. Pole piece  148  tapers toward its lower end and is disposed adjacent to a pair of Hall sensors  102 ,  103  carried by a circuitboard  150 . Coil  146  is connected by leads  152  to circuitboard  150 . Conductors  154  extend from circuitboard  150  through conduit  112  to connector  114   a  for connection to controller  52   a  (FIG.  10 ). Subassembly  90   a  is mounted on a spring-biased upper bracket assembly of the type illustrated in FIGS. 2-4 for following vertical movement of the conveyor due to plate and conveyor wear, etc. while maintaining constant spacing between the upper and lower surfaces of the conveyor and the respective electromagnetic assemblies. This embodiment may include longitudinally spaced rollers  80  disposed on opposite sides of arm  134 . 
     Electromagnet coils  136 ,  146  of speed sensors  48   a ,  50   a  are connected to associated amplifiers  160 ,  162  of a controller  52   a  (FIG. 10) for suitably energizing the electromagnets. Hall sensors  102 ,  103  of the respective speed sensors are connected through associated signal conditioning electronics  116 ,  120  to motor controller  118   a , which controls operation at motors  40 ,  44  to maintain desired constant linear speed at the conveyors, as previously described. Thus, the embodiment of FIGS. 7-10 replaces the permanent magnet  96  in the embodiment of FIGS. 2-6 with an associated electromagnet, and positions electromagnets both above and below the conveyor for enhanced sensitivity. 
     There has thus been disclosed a glass machine system, and particularly a glassware linear conveyor speed sensor, that fully satisfies all of the objects and aims previously set forth. The invention has been disclosed in conjunction with presently preferred embodiments thereof, and a number of modifications and variations have been discussed. Other modifications and variations will readily suggest themselves to persons of ordinary skill in the art in view of the foregoing description. The invention is intended to embrace all such modifications and variations as fall within the spirit and broad scope of the appended claims.