Sand Moisture Control System.Inadequate moisture content of the sand causes problems at molding. Accurately measuring the moisture in the sand helps to produce high quality sand molds. Trisat Hygrometrics, San Angelo, Texas San Angelo is a city in and the county seat of Tom Green CountyGR6, Texas, United States. It is also the principal city of the "San Angelo, Texas Metropolitan Statistical Area" that includes all of Irion and Tom Green county. , has introduced FoundryStar, an all-digital continuous foundry molding sand (Founding) a kind of sand containing clay, used in making molds. See also: Molding moisture controller. The system achieves a measurement accuracy of better than 0.1% by employing the dielectric dielectric (dī'ĭlĕk`trĭk), material that does not conduct electricity readily, i.e., an insulator (see insulation). A good dielectric should also have other properties: It must resist breakdown under high voltages; it should not measurement principle through digital signal processing See DSP. Digital Signal Processing - (DSP) Computer manipulation of analog signals (commonly sound or image) which have been converted to digital form (sampled). techniques. The digital algorithm automatically compensates for density variations of the sand and ensures ultimate stability of the measurement over time and temperature. The compact sensor system measures the moisture content of the molding sand before it enters the mixer and adds an appropriate amount of water during the mixing process. The system automatically conditions the sand to reach the optimal moisture content of natural or synthetic molding sand in both batch and continuous mixer plants. In batch mixer applications, the sensor computes an accurate moisture average while the mixer or the scale is being filled. After filling, the water flow is enabled through a solenoid valve A solenoid valve is an electromechanical valve for use with liquid or gas controlled by running or stopping an electrical current through a solenoid, which is a coil of wire, thus changing the state of the valve. . Flow sensor A flow sensor is a device for sensing the rate of fluid flow. Typically a flow sensor is the sensing element used in a flow meter, or flow logger, to record the flow of fluids. pulses are fed back to the sensor and the valve is kept open until the required water is added. The water quantity is computed on the basis of the actual moisture content, the moisture set-point and a given amount of sand. Temperature also can be factored in to compensate for evaporation evaporation, change of a liquid into vapor at any temperature below its boiling point. For example, water, when placed in a shallow open container exposed to air, gradually disappears, evaporating at a rate that depends on the amount of surface exposed, the humidity losses. In continuous mixer applications, the sensor computes the incidental sand moisture at regular intervals while sand is being delivered to the mixer. Sand quantity pulses or the combination of momentary load and conveyor speed pulses from an external dynamic weighing system provide information on the sand quantity. For each incremental sand quantity, the amount of required water is computed and delivered through a servo-assisted linear valve. The actual water flow is checked through a flow meter flow meter Device that measures the velocity of a gas or liquid. It has applications in medicine as well as in chemical engineering, aeronautics, and meteorology. Examples include pitot tubes, venturi tubes, and rotameters (tapered graduated tubes with a float inside that is feedback and a control loop. If the required amount of water becomes smaller than the dynamic range of the flow meter, the water supply shuts down completely to avoid trickle loss errors. A low cost and a high performance sensor are offered. The high performance sensor is attached in a way that sand falls freely on the sensor plate, where it is removed by a rotating wiper. The low cost sensor must be incorporated in a chute. Both systems use identical software and a touch-sensitive panel for data display and operator interaction. |
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