Caster

Abstract: A two-dimensional heat-transfer model for transient simulation and control of a continuous steel slab caster is presented. Slab temperature and solidification are computed by the model as a function of time-varying casting speed, secondary spray cooling water flow rates and temperature, slab thickness, steel chemistry, and pouring and ambient temperatures. Typically, the solidification path, temperature-solid fraction relationship, is prescribed. However, if these data are not available, a microsegregation solidification model that approximates the effects of steel chemistry and cooling rate is incorporated in the caster model. Measured slab surface temperatures recorded from an operating caster are compared with predictions from the transient model. These demonstrate that the model typically can predict the temperature response at the slab surface within 30 °C. Results of several simulations are given to demonstrate the effects of changing casting conditions on the slab thermal profile, end of liquid pool, and solidification end point. A control methodology and algorithm suitable for online control of a continuous casting machine is described, and the ability to control the surface temperature profile by dynamically adjusting secondary spray cooling flow rates is demonstrated by simulation. Results from a preliminary version of the model that is capable of running in real time are presented and are compared with the slower, but more realistic, version of the model.

Abstract: A braking system (30) for a hospital bed (20) having a base frame (28) includes a plurality of caster devices (44) rotatably coupled to the base frame (28). Each caster device (44) has a caster frame, a wheel (55) rotatably attached to the caster frame, a brake (48) attached for movement with respect to the caster frame between a first position in which the brake (48) inhibits rotation of the wheel (55) and a second position in which the brake (48) permits the wheel (55) to rotate freely. The caster device (44) also includes an actuator (128), a plurality of pedals (56) each adjacent to a different one of the plurality of caster devices (44) and coupled to the actuator (128) for movement of the brake (48) between the first position and second position in response to movement of the pedal (56), and a linkage coupled to all of the actuators (128) of the plurality of caster devices (44) so that movement of any one of the plurality of pedals (56) causes movement of all of the actuators (128).

Abstract: A drive system base or platform, such as for a mobile robot, is disclosed having multiple caster wheels, each wheel having its own first motor for independent driving and its own second motor for independent steering. Each wheel is rotably and pivotably mounted in a separate wheel module, which includes both the driving and steering motors associated with the wheel. All of the wheel modules on the base are identical and interchangeable. The two motors of each module are mounted side by side in a vertical arrangement for compactness. Each wheel module includes a suspension for allowing each wheel to move vertically and independently relative to the base. The hub and tread of each wheel are each cast concentrically around a bevel drive gear in an offset manner to provide a wheel and bevel gear that turn more smoothly and precisely.