Patent Grant
6921322
This invention relates to a device for and method of refinishing a surface in situ. Such a surface can include the surface of a work piece in a valve such as a rotary valve.
A rotary valve is a valve that rotates intermittently to control fluid flow. A rotary valve typically includes a track plate, a rotor plate, and an upper pressure-tight shell or casing. The casing and the trackplate form a fluid-tight housing totally enclosing the rotor plate. The rotor plate is maintained in fluid-tight contact with the track plate, and rotates in a horizontal plane. It 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 trackplate, in order to direct the flow of fluid within the valve.
Wear and tear to the surface of the trackplate during use can cause it to be 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 not affected. To avoid the significant cost of replacing a worn workpiece, the surface of the workpiece is refinished, by a process commonly referred to as ‘resurfacing.’
Although portable-lapping machines can be used to repair and refinish a workpiece surface in the field, they are suitable only for minor repairs. When the workpiece has been heavily damaged, or when precision resurfacing is necessary, lapping is impractical due to its limited capabilities for precision refinishing, excessive time, and wear to the parts. This is because the lapping machine's grinding and resurfacing apparatus produces an irregular surface finish, causing an ineffective seal within the rotary valve.
When use of a lapping machine is unsuitable, the trackplate must be removed and outsourced for resurfacing. This involves removing the trackplate, and shipping it to the site of a specially designed resurfacing machine. Trackplates used in large rotary valves are difficult to remove due to the size of the valve itself, and shipment is expensive and slow. Thus, in the case of rotary valves that are very large, such as those used in petrochemical refineries, this process is extremely costly and time consuming, thereby causing the refinery lost production time. It is therefore desirable to develop a resurfacing apparatus that can be used for precision resurfacing of heavily damaged workpieces “in situ,” that is, while remaining on-site at the location where the rotary valve is installed, and preferably, to further develop a process for resurfacing the surface of the trackplate without removing it from the rotary valve.
The present invention is directed to an apparatus, device, and methods for precision refinishing a surface in situ. Preferably, the present invention is directed to a device designed to refinish a workpiece of a rotary valve in situ. This offers the significant advantage of repairing damaged precision equipment in the field to avoid the time delays and costs associated with sending the equipment back to the manufacturer for repair. Preferably, the surface is refinished so that it is flat to no greater than a total variance of 0.002 inch, and less for smaller diameters. The diameters range from less than 18 inches to nearly 6 feet, with a finish of sixteen (16) micro-inch or better.
In one aspect, the present invention is directed to a machine apparatus for refinishing a workpiece surface in situ. The device includes an upper framework, a grinding assembly, a lower framework, an adjuster assembly system, and a power source attachment assembly. In one embodiment of the present invention, the upper framework includes a housing, a rotation assembly, a spindle assembly connected to the rotation assembly, a connection system for attaching the housing to the spindle assembly, and a drive mounting plate. The drive mounting plate connects the spindle assembly and the rotation assembly to the grinding assembly. The housing can be of any shape that is suitable for mounting on the particular workpiece to be resurfaced. In one preferred embodiment, the housing has at least three outward surfaces and a passage that extends axially through the housing. Preferably, the housing is ‘rigid,’ meaning that it is of a material that is capable of limiting vibration and motion. The rotation assembly can include a drive motor, a drive shaft, a hollow shaft reducer coupled to the drive shaft, and a rotary union. Preferably, the drive shaft extends axially through the passage of the rigid housing.
The rotary union (a.k.a., ‘rotating union’ or rotary/rotating ‘joint’) allows a working fluid, e.g., an hydraulic fluid, to be introduced into the hydraulic system of the grinding assembly, while the grinding assembly is rotating without fouling or twisting hydraulic hoses. Where the refinishing apparatus is powered by pneumatic or airpowered equipment, the rotary union acts similarly to prevent air hoses from becoming fouled or twisted. The spindle assembly can include a spindle, a spindle frame attached to the spindle, a plurality of spindle bearings that are disposed between the spindle and the spindle frame, a spacer that is disposed between the spindle and the spindle frame, and a top and bottom spindle cover, both of which are independently and securely attached to the spindle and the spindle frame. The connection system can include a plurality of mounting brackets.
In yet another embodiment, the grinding assembly includes a feed assembly and a grinding wheel assembly coupled to the feed assembly. The feed assembly can include a feed slide and a feed arm coupled to the feed slide. In another preferred embodiment, the grinding wheel assembly includes a wheel drive motor assembly, a grinder spindle connected to the wheel drive motor assembly, and a grinding wheel rotably coupled to the grinder spindle. More preferably, the grinding wheel assembly further comprises a wheel guard mounted on the grinder spindle housing. Optionally, the grinding wheel assembly can further comprise a single point surface-removing tool mounted to the wheel guard for machining gouges or deep grooves from the workpiece surface prior to grinding. In such an embodiment, the wheel guard is adapted for receiving the single point tool.
In still another embodiment, the lower framework includes a base ring and an adapter ring, or adapter plate. Preferably, the base ring is ‘rigid,’ meaning that it is of a material that is capable of limiting vibration and motion. In a preferred embodiment, the adapter ring is removably attached to the base ring and the surface to be refinished. The adapter ring attaches to the workpiece and can be easily modified or customized for different sizes and types of workpieces, as would be known to those skilled in the art.
The invention further includes a plurality of adjuster assemblies for adjusting the vertical height and balance of the upper framework over the lower framework. The adjuster assembly permits very precise vertical motion, e.g., to increments of ten thousandths of an inch. Preferably, the refinishing apparatus includes at least three or more adjuster assemblies; three adjuster assemblies is optimal for ease of leveling, but greater numbers of adjuster assemblies can be used where increased stability or shock absorption is desired.
The adjuster assembly system preferably includes an upper assembly (top sub-assembly, a lower assembly (bottom sub-assembly), and an adjuster screw that connects the upper assembly to the lower assembly. The upper assembly adjuster is connected to the upper framework, and the lower assembly is connected to the lower framework. The upper assembly preferably includes a lock collar attached to the adjuster screw, a screw bushing assembly attached to the lock collar, a thrust bearing assembly attached to the screw bushing assembly, and a thrust collar attached to the thrust bearing assembly. Another alternative embodiment is for the lower assembly to include a torque collar attached to the adjuster screw, at least one base adjuster screw attached to the torque collar, at least one spherical bushing attached to the base adjuster screw, at least one retainer ring attached to the spherical bushing, at least one spherical bearing adapter disposed between the torque collar and the spherical bushing, and at least one retaining ring attached to the spherical bushing adapter.
In another aspect, the invention features a dresser assembly for in-position restoration of a grinding wheel. The dresser assembly includes a dresser slide housing, a dresser slide movably disposed within the dresser slide housing, a dresser tool attached to the dresser slide, and means for placing the dresser slide housing in functional proximity to a grinder wheel.
The invention further features a method of refinishing a trackplate surface by attaching any one of the refinishing apparati described above to a workpiece, and allowing the grinding assembly to rotate while refinishing the workpiece. Preferably, the grinding assembly moves across, e.g., by rotating over, e.g., rotating around the circumference of, the trackplate. More preferably, the trackplate is in a stationary position. Optionally, the method of refinishing can further include dressing the grinding wheel with a dressing assembly that is in functional proximity to dress the grinding wheel while it is in position in the grinding assembly.
A preferred embodiment of the present invention is shown in the accompanying drawings which, together with the description thereof, will serve to exemplify the invention. The particular structure illustrated can be modified by those skilled in the art without departing from the broad scope of the invention.
This invention is specially designed to machine and grind precision surfaces on, equipment used in, e.g., the chemical process industry, without removing the equipment from its on-site location, i.e., while the workpiece remains in the field, or ‘in situ.’ By repairing damaged or worn precision equipment in the field, the great time delays and high cost of sending the equipment back to the manufacturer for resurfacing are avoided.
In most turning and grinding applications used in the manufacture of large chemical process equipment, the material that is being machined, the workpiece, is rotated, while the machine tool is held in a stationary position. The present invention is able to depart from this practice because the workpiece can be machined in situ. In particular, where the workpiece is the trackplate of a rotary valve, the workpiece can be resurfaced while remaining at the plant, e.g., refinery plant, where it is normally used. Even more preferably, the workpiece can optionally be resurfaced while left in its native position on the equipment of which it is a normal part, e.g., on the stator plate of the rotary valve. In this case, the machine tool (here, a precision-grinding spindle) is rotated, and the workpiece is kept in a fixed position. This is accomplished by mounting a precision-grinding spindle rigidly to a stiff frame so that the spindle can be fed radially in or out while simultaneously being spun at predetermined speeds about the center of the workpiece.
The preferred embodiment described below, and illustrated in the accompanying drawings, features a self-contained, portable hydraulically powered apparatus for performing precision grinding operations on metal disks of up to, e.g., 54 inches in diameter, for example and without limitation, 18, 24, 34, 40, 48, 54, 60, or 65 inches in diameter. The apparatus is bolted to the surface of the disk to be refinished using studs and nuts, and is leveled using special precision leveling equipment, referred to below as ‘adjuster assemblies.’ During operation, the adjuster screws within the adjuster assemblies are turned in precision increments to set the depth of cut. The grinder is then rotated on an arm about the center of the disk, by the use of a hydraulically driven speed reducer, rotor, bearing assembly. A hydraulic motor powers the grinder. The speed of the wheel and arm, and the speed of the feed, are adjustable, and are set using flow control valves. The grinder can be fed radially back and forth across the disk using a precision slide that operates at optimal feed rates through the use of a belt driven speed reducer and a torque-limiting coupling. Optionally, the invention further includes a wheel guard to which is mounted a precision threaded single point diamond nib for dressing the grinding wheel. The wheel can be dressed at 0.00125-inch increments. Increments can be identified with dots adjacent the threaded nib. The screwdriver slot in the nib is used with the dots to determine the amount of the wheel to be dressed. In another option, a single point tool can be mounted to the wheel guard. This embodiment of the invention is described in further detail by
Referring to
The rigid housing 110 can be any suitable housing, but is preferably a material that is of a stiffening construction and of a mass to weight ratio that is capable of absorbing vibrations or other movements during operation to prevent vibrations from causing imperfections in the workpiece surface 501.
The rigid housing 110 supports the spindle assembly 130 and is attached directly to the spindle frame 132 by mounting brackets 141. Rigid housing 110 includes outward surfaces 110a, 110b, and 110c, and a passage 115 that extends axially through the rigid housing 110. Hoses 160 extend through passage 115 for the flow of, e.g., hydraulic fluid or pneumatic air pressure.
The spindle assembly 130 is fastened to the drive mounting plate 150 through the spindle 131 and rotates with the drive mounting plate 150 through the rotation assembly 120. Spindle assembly 130 includes a spindle 131, a spindle frame 132, main spindle bearings 133, precision spindle bearings 134, spacers 135, a top spindle cover 136, and one or more bottom spindle covers 137. The spindle frame 132 is supported by the rigid housing 110 and by precision spindle bearings 134. The precision spindle bearings 134 rest on a spacer 135 and on the bottom spindle cover 137. The precision spindle bearings 134 are disposed between the spindle frame 132 and the spindle 131, while the spacer 135 is disposed between the bottom spindle cover 137 and the spindle 131. The top spindle cover 136 is secured to the spindle 131, and is supported by a main spindle bearing 133 and by the spindle frame 132.
Rotation of slide arm assembly 216 is accomplished by rotation assembly 120. The rotation assembly 120 includes a drive motor 121, a drive shaft. 122, a hollow shaft speed reducer 123 and a rotary union 124. The rotary union 124 is coupled to the hollow shaft speed reducer 123, which is coupled to the drive shaft 122 through a hollow shaft with key 125, or by other appropriate means. The rotary union allows a working fluid, e.g., hydraulic fluid, to be introduced into the hydraulic system of the grinding assembly, while the grinding assembly is rotating without fouling or twisting hydraulic hoses. Where the refinishing apparatus is powered by pneumatic or air-powered equipment, the rotary union acts similar to prevent air hoses from becoming fouled or twisted. Rotary unions suitable for use in the refinishing apparatus of the invention include, without limitation, Deublino® Rotating Unions, Deublin Company, Waukegan, Ill. Flow control valves can be located, e.g., intermediate between the rotary union and the hydraulic unit (not show), as would be known to one skilled in the art.
The drive mounting plate 150 and the spindle 131 are rotated together by the hollow shaft speed reducer 123. Preferably, the drive mounting plate 150 and the spindle 131 are rotated about a central axis of the workpiece 500.
As further illustrated in
The grinding wheel assembly 230 includes a wheel drive motor 231, a grinder spindle 232, a grinder spindle housing 233, grinder spindle adapter brackets 234, and a grinding wheel 235. Coupler 236 is between grinder spindle 232 and the hydraulic motor. The wheel drive motor 231 is a direct drive motor, but as is well known in the art, can be any suitable motor, and is mounted on one end of the grinder spindle 232. The grinder spindle 232 in enclosed by the grinder spindle housing 233. The grinder spindle housing 233 is also coupled to the slide arm assembly 216.
Optionally, a single point tool (not shown) can be mounted on the wheel guard 611 for machining any deep grooves, indentations, or chips from workpiece surface 501. Machining with a single point tool is optionally performed to prepare the workpiece surface 501 for subsequent grinding by-the grinding wheel 235.
The lower framework 300 includes base ring 301 and an adapter ring 302. The adapter ring 302 is securely attached to the workpiece 500. Preferably, the adapter ring 302 is attached through a number of removable screws and studs 303. The adapter ring supports the rigid base ring 301. The base ring 102 provides circumferential bottom support for the equipment. A base ring 301 includes an upper flange 304, to which the adjuster assemblies 400 mount to, and a lower flange 305, to which the adapter ring 302 is attached. The base ring 301 must be rigid so that it can also absorb any vibration Adapter ring 302 which can be sized to accommodate various size workpieces.
Adjuster assembly 400 has two sub-assemblies, a top sub-assembly 410 and a bottom sub-assembly 430. The top sub-assembly 410 is mounted on the rigid housing 110 of the upper framework 100. The bottom sub-assembly 430 is mounted on the base ring 301 of the lower framework. The top sub-assembly 410 includes a top sub-assembly housing 411 provided with a plain guide bearing 460 for the adjuster screw 440. A lock collar 412 is provided to prevent rotation of the adjuster screw 440. Thrust bearing assembly 413 and thrust collar 414 bear the load The bottom sub-assembly 430 includes a bottom sub-assembly housing 431 for the spherical bearing assembly 432. The spherical bearing assembly 432 includes a spherical bearing 433, which is captured in bottom sub-assembly housing 431 with snap rings 434, a mating precision internal thread 435, and a torque collar 436 to prevent rotation of the spherical bearing assembly 432. The spherical bearing assembly 432 allows for misalignment between the rigid housing 110 of the upper framework 100 (not fully shown) and the base ring 301 of the lower framework 300 (not fully shown), and prevents binding, or locking up, of the threaded parts, adjuster screw 440 and internal thread 435.
The device shown in
In
The grinder wheel guard can be reworked to accommodate attachment of a dresser assembly, as exemplified by the diagrams shown in
The resurfacing apparatus of the invention can be run in conjunction with any power source, including without limitation, an electric motor, a pneumatic motor, or a hydraulic motor. Where the workpiece being machined is in proximity with flammable or volatile substances, as is the case when used to refinish a rotor plate at the site of a petrochemical refinery, it is preferred that the power source be a hydraulic motor, or another power source known to those skilled in the art to have the advantage of producing few, if any, electrical sparks.
The refinishing apparatus of the invention is used according to the following example. Once the refinishing device is bolted to the workpiece 500, it must be positioned so that it runs concentric with the workpiece 500. This is done by mounting a dial indicator (not shown) on the grinder spindle housing 233 and checking the concentricity with a track wall. If an adjustment is necessary, the base ring 301 must be loosened and moved using a mallet. The base ring 301 is then secured, and the concentricity verified once again.
The machine is then setup parallel to the workpiece 500. This is done by mounting a dial indicator on the grinder spindle housing 233 and checking for parallelism with the workpiece surface 501. If an adjustment is necessary, it is done by turning the adjuster screws 440 as needed (clockwise looking down to lower the machine, counterclockwise looking down to raise the machine) while the slide arm assembly 216 is slowly rotating about the center of the workpiece 500. The dial indicators mounted at the three-adjuster assemblies 400 are then all “zeroed” out and locked.
With the refinishing device stopped and all power disconnected, a grinding wheel 235 is mounted to the grinder spindle 232 and secured in place with a special washer and nut (not shown) and brought up snug using a spanner wrench. The wheel guard is then mounted and bolted up.
The grinding wheel 235 is positioned just inside the outer diameter of base ring 301 and above the face of the workpiece surface 501 to be ground. With the refinishing device stopped and all power disconnected, the grinding wheel 235 is lowered evenly in small increments, using the three (3) adjuster assemblies 400, until the grinding wheel 235 just touches the surface to be ground. The grinding wheel 235 is positioned just outside the surface to be ground. The slide arm assembly 216 can then begin rotating slowly about the center of the workpiece 500, and speed can be increased as necessary. The grinding wheel 235 can then be fed in towards the center of the workpiece 500. Grinding can be continued until the entire surface has been traversed. The direction can be reversed and the wheel fed back out to the original starting point just outside the surface to be ground. Again, the grinder is lowered evenly to the desired depth of cut and begins feeding the wheel in towards the center of the workpiece 500. Cut depths can be, for example, 0.010 inches, ranging from, without limitation, 0.03 to 0.5×10−3 inches to a maximum of 0.1 inches per run. The wheel speed, arm assembly speed, feed rate, and depth of cut can be varied at the discretion of the operator, acceptable settings are known to those skilled in the art. The above procedure is repeated until the required specification for finish and flatness is obtained.
Optionally, the grinding wheel 235 should need to be dressed in position. For example, the grinder is turned on at a desired speed. With the adjustable dresser tool 604 backed out, insert the dresser slide 603 is inserted into the dresser slide housing 602 until the dresser tool 604 is adjacent the face of the grinding wheel. An estimation of the clearance is made, and the dresser slide 603 is manually removed from the dresser slide housing 602. The dresser tool 604 is turned inward through the medium of its microthread 607 using a spade tip screwdriver. The face of the dresser slide 603 is provided with radial lines adjacent the dresser tool 604. Using these marks (lines) and an indicator-screwdriver slot on the adjustable dresser 604 tool, adjustments are made as required. The dresser slide 603 is returned to the dresser housing 602 and manually moved across the face of the wheel. This procedure is repeated until the wheel has been dressed as desired.
After resurfacing, surface finish and flatness is measured across the entire face of the disk. A profilometer is used to verify the finish against the required workpiece specifications. Flatness requirements can be verified using various methods, such as an electronic level, a laser, an optical flat with a monochromatic light or a precision beam with precision shim stock. In some embodiments, the surface needs to be flat to no greater than a total variance of 0.002 inches and less for workpieces with smaller diameters. The present invention can finish a workpiece to a 16 micro inch finish or better. Specifically, the present invention can refinish workpieces anywhere from 4 inches to 84 inches in diameter. More preferably, the present invention can be used to refinish workpieces that range in diameter from 18 inches to 72 inches.
Generally, the refinishing device according to the present invention can refinish the surface of any equipment in need thereof. Preferably, the invention is used to refinish a surface through precision machining and grinding, resulting in a flat, precise, and mirror-like surface finish. The present embodiments are therefore to be considered in respects as illustrative and not restrictive, the scope of the invention being indicated by the appended claims rather than by the foregoing description, and all changes which come within the meaning and range of the equivalency of the claims are therefore intended to be embraced therein.
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| Number | Date | Country | |
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