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.
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.
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.