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The present invention relates to rotary grinders and more particularly to vertically axised rotary grinders.
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A rotary valve is a valve, a part of which rotates intermittently to control fluid flow, such as in an oil refinery. A rotary valve typically includes a track plate, a rotor plate and an upper pressure-tight shell or casing. The casing and the track plate form a fluid-tight housing totally enclosing the rotor plate. The rotor plate is maintained in fluid-tight contact with the track plate and typically rotates in a horizontal plane. The rotor plate has a slick, smooth surface, referred to as a “seal surface,” and a number of channels and holes and/or ports that communicate with corresponding channels, holes and/or ports in the track plate in order to direct the flow of fluid within the rotary valve.
Wear and tear to the surface of the track plate during use can cause it to become damaged to such an extent that the necessary sealing required for proper fluid control is impaired. Such damage can be caused by corrosion, erosion, friction or distortion, or by the presence of foreign objects. Once the surface is damaged, either repair or replacement is necessary to reestablish an acceptable seal, so that the function of the rotary valve for the particular fluid control application is restored. To avoid the significant cost of replacing a worn track plate, the surface of the track plate may be refinished by a process commonly referred to as “resurfacing.”
It is known in the prior art to use a rotary grinder to refinish a surface of an item (a “workpiece”), such as a track plate. Due to the complexity, time and expense required to remove or ship such items, it is advantageous to be able to refinish the surface of a track plate without shipping the track plate or the entire valve to a refinishing facility.
Apparatus, such as those described in U.S. Pat. No. 6,921,322, for refinishing the surface of a track plate on site generally include height adjusting mechanisms to control depths of cuts made by a traversing rotary grinding wheel. A typical prior art refinishing machine includes a lower frame member and an upper frame member connected to each other by three adjustable assemblies spatially distributed around the peripheries of the frame members. In use, the lower frame member is rigidly attached to the track plate, and the grinding wheel is attached to the upper frame member. Adjusting the assemblies changes the height and orientation of the upper frame member and, consequently, the height and orientation of the grinding wheel, with respect to the lower frame member and the track plate. The height of the grinding wheel determines the depth of a refinishing pass over the track plate.
Adjusting the height of the grinding wheel to set the depth of a refinishing pass requires separately and precisely adjusting each one of the three assemblies. For a given refinishing pass, all the assemblies must be adjusted by precisely the same amount, which is difficult to do efficiently and consistently without stopping the machine, even for skilled operators. Many passes of the grinding wheel are typically required to resurface a track plate, because each pass removes only a small amount of material. Consequently, refinishing a track plate can be time consuming and labor intensive.
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An embodiment of the present invention provides a rotary grinder system that may be coupled with a workpiece. The rotary grinder system includes a support frame, a grinder assembly and a grinder wheel. The support frame may include an upper frame coupled to a lower frame. The support frame has an engagement region configured to be coupled to the workpiece. The grinder assembly is coupled to the support frame. The grinder assembly includes an axial arm and a radial arm coupled to the axial arm. The radial arm is coupled to the axial arm in a substantially orthogonal orientation. The radial arm is coupled to the axial arm, such that the radial arm rotates about an axis of the axial arm. The grinder wheel is rotatably coupled to the radial arm of the grinder assembly via a grinder wheel driver. The grinder wheel is translatable along the radial arm. The rotary grinder system also includes a single point axial positioner configured to drive the radial arm of the grinder assembly along the axis of the axial arm. The single point axial positioner is configured to drive the radial arm translationally, with respect to the support frame.
The single point axial positioner may include a ball screw system and, optionally, a mechanical slide. Optionally or alternatively, the single point axial positioner may be configured to drive the radial arm though translation of the axial arm or through rotation of the axial arm or through extension of the axial arm.
The grinder assembly may be coupled to the support frame via at least one slide assembly connected to the axial arm of the grinding assembly and to the support frame.
The axial arm may include a telescoping arm configured to change length upon application of force from the single point axial positioner.
The grinder wheel may be coupled to a mechanical slide on the radial arm and configured to translate along an axis of the radial arm. In this case, translation of the mechanical slide along the radial arm displaces the grinder wheel.
The radial arm may include a telescoping arm, and the grinder wheel may be coupled to the radial arm.
The rotary grinding system may also include a counterweight coupled to the grinder assembly and to the support frame. Such a counterweight may be configured to urge the grinder assembly in a direction away from the workpiece, along the axis of the axial arm. The counterweight may include a hydraulic device, a spring and/or a mass-based counterweight.
The rotary grinding system may also include a counterweight that is movably coupled to the radial arm. Such a counterweight may be configured to move along the radial arm a distance proportional to, and in a direction opposite, the grinder wheel.
A rotary grinding system according to claim 13, wherein the counterweight includes at least one of a chain drive, a screw drive and a dual rack with an interconnecting gear drive.
A rotary grinding system according to claim 1, further comprising a micrometer adjustable dressing tool configured to dress the grinder wheel.
Optionally, the rotary grinding system includes one or more eccentric pins. Each such eccentric pin extends through a respective hole defined by the support frame and into the workpiece. Rotation of at least one of the eccentric pins laterally displaces the support frame, relative to the workpiece.
Optionally, the rotary grinding system includes at least one support member connected between the support frame and the grinder assembly. Such a support member may be configured to selectively support weight of at least a portion of the grinder assembly.
Optionally, the rotary grinding system may be computer numerically controlled. Actuators may be employed to adjust various elements of the rotary grinding system. A computer numerical control may be electrically connected to a first actuator, which may be configured to adjust the single point axial positioner. In addition, the computer numerical control may be electrically connected to a second actuator, which may be configured to translate the grinder wheel driver along the radial arm. Each of the actuators may include an encoder for measuring the magnitude of the respective adjustment and translation.
Optionally, the grinder assembly includes at least one slip ring configured to transmit electrical signals to the radial arm during rotation of the radial arm. Optionally or alternatively, the grinder assembly may include at least one hydraulic rotary union configured to transmit hydraulic fluid to the radial arm during rotation of the radial arm.
The grinder assembly may include at least one mechanical stop on the axial arm or on the radial arm.
The grinder wheel may be retractable translationally beyond a zero point on the radial arm, so as to expose a diameter of the workpiece.
The rotary grinding system may include an adapter plate. In this case, the support frame may be configured to be coupled to the workpiece via the adapter plate.
BRIEF DESCRIPTION OF THE DRAWINGS
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The invention will be more fully understood by referring to the following Detailed Description of Specific Embodiments in conjunction with the Drawings, of which:
FIG. 1 is a cut-away view of a prior art rotary valve assembly, with which embodiments of the present invention may be used;
FIG. 2 is an exploded perspective view of a rotary grinding system, in accordance with an embodiment of the present invention;
FIG. 3 is a close-up perspective view of a height-adjustable connector of the rotary grinding system of FIG. 2;
FIG. 4 is a perspective view of the rotary grinding system of FIG. 2, as seen from one side;
FIG. 5 is a perspective view of the rotary grinding system of FIG. 2, as seen from another side;
FIG. 6 is a cutaway view of the rotary grinding system of FIG. 2;
FIG. 7 is another cutaway view of the rotary grinding system of FIG. 2;