Machine controller

With different approaches to monitor and control the basic parameters of the motor, i.c. 4, /, and sin 6, many tnorc alternatives arc possible to achieve the required speed variation in an a.c. machine. Control of these parameters by the use of an encoder can provide an accuracy in speed control as good as a d.c. machine and even better. 

Indo-British Workshop on Power Electronies, Energy Saving Machine Control and Simulation Vol. I and 11, 14-18 December 1992, Organized by IIT, Delhi, India,... 

The machine control system was set in accordance with the parameters determined during simulation prior to delivery to the site. Following re-routing and hook-up of the piping, the compressors were run to a maximum flow at 2.71 bar (absolute) and 480°C. The generator was disconnected from the grid and the expander tripped accordingly. 

In addition to the building parameters, there are often some requirements from suppliers of processes and equipment to make sure their parts function properly. This may mean that the requirements for the equipment decide the target levels (e.g., in pharmaceutical and electronics industries). In other cases there are restrictions on deviations from the target levels (e.g., on temperature for machine control system or on humidity and vibration for optical measure nient systems). ... 

The term process control is often used when machine control is actually performed. As the knowledge base of the fundamentals of the molding process continues to grow,... 

Explain how each of the following machine control parameters can affect flash formation in injection molding ... 

Fig. 3.10 Washing machine control and measured suds quality.

However, very economical measurement of acceleration is possible when the washing machine is equipped with a high-resolution analog pressure sensor with microprocessor control. These pressure sensors come as a separate part or are integrated directly on to the PCB of the washing machine control. They work as differential pressure sensors and measure the static pressure via a hose in the lower part of the suds container, thus measuring the water level in the suds container (Fig. 5.57). 

Since the 1960 s, stamp paper has been treated with fluorescent or phosphorescent phosphors. Since the stamp is stuck to the top right-hand corner of the letter, its recognition by the machine serves to establish the position of the letter and enables machine control of the correct positioning for postmarking and reading. Doped zinc sulfides with average particle sizes of 5-6 pm are used as afterglow phosphors. 

The hardware architecture must be flexible with respect to bus technology, expansions, network integration and modem access. The use of standard components and software and also a maintenance-friendly design will simplify qualification and validation for both the manufacturer and the user. It is advisable to design the machine control separately from the data management (i.e. recipe and data administration) to ensure that if there is a failure, loss of data does not result in losing a batch. Pro-... 

A detailed study of mold filling was done by Krueger and Tadmor (6). The various stages of the injection process was followed by pressure gauges in the mold, as shown in Fig. 13.5. In this experiment polystyrene (PS) was injected into a shallow rectangular cavity with inserts as shown in the figure. Pressure transducers were placed in the nozzle, runner, and mold cavity their output was scanned every 0.02 s and retrieved by a computer. The nozzle pressure was set by machine controls to inject at a constant 10,000 psi and, upon mold filling, to hold the pressure at 5500 psi. 

At current development levels, the operator must implement the solution where it could be made directly by the machine controls. For example, where too low shrinkage can be corrected by a decrease in holding pressure. Because one is concerned with the risks of automatic implementation, and believes that, at least for a long time to come, there will always be problems requiring manual operations. An example is material clogging the throat of the hopper a problem which can be minimized by proper equipment design but never eliminated. Another is metal wear.163... 

The term process control has often been used when machine control is actually performed. As the knowledge base of the fundamentals of the molding process continued to grow, the control approach is moving away from principally press control and closer to real process control where material response is monitored and then moderated or even managed (Chapter 3). 

Leading the processing growth was the expansion of twin-sheet and pressure-formed plastic products. Fueled mostly by advances in mold technology, material developments, and thermoforming machinery capabilities, technology improvements in the form of machine controls have led to machine designs that are faster and more consistent than was previously possible. As an example advanced materials and... 

The mold can be modified to meet certain different shapes. The molding can be made either by withdrawing cores or by special press motions that partially open the mold halves (such as the compression molds used in coining to provide 2-D action 3-D mold actions are also used). The degree of foam density, wall thickness, and surface finish depends on the foam mixture (constituents and amounts). The machine controls the time cycle and the mold action required. 

Because the plastic is processed between the required heat and its critical heat of degradation, the time of heat becomes extremely critical and an important part of the complete process. For example the processor will minimize the amount of melt in the nip of the rolls. The residence time of the plastic flux at high heat must be controlled and limited. PVC is especially sensitivity to heat and time at heat. What is required is proper setting of the machine controls and operation within set limits. The processing variables of a PVC plastic (such as flow, heat stability and softening point) are strongly influenced by polymerization technique, MWD, and the extent of any polymerization (Chapter 1). 

Any of these pumps can be controlled by a microprocessor that is sensitive to the actions of an extruder or molder. The microprocessor can control the pump, precisely adjusting the liquid color flow. The pump electronics can interface with process machine controls, so pumping rates can vary in extrusion with screw speed, or with an injection molder cycle. See Figure 20.2 for photographs of typical liquid color pumps. Probably the most popular supplier of the peristaltic pumps is the Maguire Company. 

F.M. Proctor, B. Damazo, C. Yang and S. Frechette, Open Architectures for Machine Control, NISTIR 5307, National Institute of Standards and Technology, 1993, Gaithersburg, MD,... 

While machine control is important, it is the polymer state (pressure, temperature, and morphology) that directly determines the molded part quality. As such, recent technology developments have focused on closing the loop between the machine parameters and the polymer state. Conformal cooling and pulsed cooling are two molding technologies that have been... 

Grakoui A, Bromley SK, Sumen C, Davis MM, Shaw AS, Allen PM, Dustin ML The immunological synapse a molecular machine controlling T cell activation. Science 1999 285 221-227. 

Darius, I.H. Rule based control, a new tool, Proc.2nd Int.Conf.Machine Control Systems, pp.121-128, May 1987. 

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