1、Best Practices Entry: Best Practice Info:a71 Committee Approval Date: 2000-04-19a71 Center Point of Contact: MSFCa71 Submitted by: Wil HarkinsSubject: Robotic Removal and Application of SRB Thermal Systems Practice: When designing robotic systems for removal and application of thermal protection mat
2、erials, pay close attention to support fixture indexing, precision positioning, optimum sequencing, and protection against robotic cell environmental conditions. By integrating proven hardware and software practices with equipment and facility design and operation, the effectiveness of robotic syste
3、ms is ensured.Programs that Certify Usage: This practice has been used on the Space Shuttle Solid Rocket Booster (SRB).Center to Contact for Information: MSFCImplementation Method: This Lesson Learned is based on Maintainability Technique number OPS-03 from NASA Technical Memorandum 4628, Recommende
4、d Techniques for Effective Maintainability.Benefit:Adherence to proven robot cell design and operational practices will result in improved consistency, speed, safety, precision, and reliability and increased cost-effectiveness of robotic systems over manual or semi-automated processes.Provided by IH
5、SNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-Implementation Method:When the SRB is recovered from the ocean, disassembled for refurbishment, and reused on subsequent Space Shuttle flights, several layers of insulating materials and protective coatings must be r
6、emoved and then re-applied. Experience has shown that the use of robotic systems for insulation removal and application will improve productivity in most operations by a factor in excess of 10 to 1. Originally, the application of the SRB insulation was a semi-automatic operation. The nine ingredient
7、s (see Table 1) were measured by hand, placed in a large blender and mixer, and mixed to a uniform consistency required for spraying. This mixture was pressurized and delivered to the spray gun, which was attached to a pedestal mounted robot in the spray cell. The SRB structures were prepared by han
8、d, i.e., sanded, cleaned, inspected, and areas masked that did not require insulation. The SRB structure was mounted on a portable turntable, which was coordinated with the operation of the robot and spray gun. Then the SRB structure and the turntable were positioned into the spray cell. A technicia
9、n (with breathing air and protective equipment) was required in the spray cell during actual spraying to take thickness measurements, assist in unplugging the spray gun, and remove the wet insulation, if it did not meet specifications. The cured insulation had to meet a flatwire tensile test of 50 t
10、o 100 pounds and a toleranced thickness requirement. Adjustments were made to the delivery system and the insulation reapplied until it met specifications. Preparation of the structure for spraying and insulation required many man-hours.1. 2215 Adhesive parts A robot does not get tired.3. Will do wh
11、atever it is programmed to do and will do it repeatedly.4. Will handle various end effectors for sanding, cleaning, inspection, spraying, and thickness measurements.Table 2. Typical Reasons for Using Robots For the SRB insulation system removal, the water is filtered to contain particles no greater
12、than 5 microns. On a quarterly basis, or every 100 operating hours, high pressure water pumps are inspected and overhauled if necessary to repair or replace the pump head, pistons, or brass sleeves. Preventive maintenance is performed regularly.Provided by IHSNot for ResaleNo reproduction or network
13、ing permitted without license from IHS-,-,-1. Gear Specifications to the environment and the application (i.e., adaption to a solvent or water spray and debris-laden environment).2. Pay close attention to the ergonomics for operators (i.e., convenience of controls, visibility, amnual override, and t
14、eaching procedures).3. Provide sufficient space in robotic facilities for support equipment, mechanisms, personnel, and operational control stations.4. Design-in automated shutdown to be activated in the event of excessive flow, pressures, temperatures, or inadvertent ingress of personnel.5. Conside
15、r the use of vision systems for alignment, completion status, inspection, and thickness measurements.6. Provide overload sensing and tactile feedback for delicate operations.7. Retain manual capability for emergency and backup operations8. Establish precise automatic indexing of fixtures with workpi
16、ece and robot to minimize setup time.9. Provide electrical grounding of all system elements10. Purchase over-rated equipment. Use only 75% or less of the capacity in the initial design to provide growth potential and operational/maintenance margins.11. Protect robot elements from solvents in the env
17、iroment to ensure continued robot lubrication.12. Train and use dedicated personnel for robotic operations13. Establish preventive maintenance requirements during the design phase based on designed-in ease of maintenance features (i.e., proper panel access, calibration test ports, equipment clearanc
18、es, etc.).Table 3. Best Practices for Robotic Systems Facility RequirementsA robotic facility of the type used for SRB insulation removal and application must allow operator visibility of the process and careful design for personnel safety and access provisions. During the noisy removal process, per
19、sonnel within a 50 ft. radius are required to wear ear protection. Operators entering the area during or immediately after spray operations are required to wear protective suits with self-contained breathing apparatus to prevent inhalation or contact with toxic fumes.Facility design must be carefull
20、y coordinated with robot design and robotic operations planning. A concurrent engineering approach is desirable in the design of robotic systems to ensure use of the correct robot, operating in an optimally designed facility, for the target application. A team of engineers and technicians representi
21、ng all applicable disciplines should be assigned full time to the project throughout design and operations. Three levels of drawings of the robot/facility complex representing: (1) components, (2) subsystems, and (3) the integrated system should proceed through Provided by IHSNot for ResaleNo reprod
22、uction or networking permitted without license from IHS-,-,-30, 60, and 90 percent design reviews. Three-dimensional solid modeling simulations using computer-aided design techniques will dramatically speed up the design process. (See the MSFC Guideline titled, “Concurrent Engineering Guideline for
23、Aerospace Systems,“ in NASA TM 4322A, “NASA Preferred Reliability Practices for Design and Test“). The facility must contain support equipment, pumping systems, material storage, control stations, and personnel dressing and clean-up.Particular attention should be paid to debris handling. Sloped conc
24、rete subfloors provide for easy debris collection and clean-up. Automated cell clean-up techniques should be considered for material removal operations.Special Design ConsiderationsRobotic systems lend themselves to the effective application of automated emergency shutdown, automatic end-effector ch
25、angeout, overload sensing, tactile feedback, and manual override. These features should be designed into the robotic system at the outset with participation of the robot vendor. Setup time can be minimized by providing pre-engineered or automatic indexing and relative positioning between the work pi
26、ece, support tooling or equipment, and robot. While mechanical systems should be over-designed for extra margins of safety against wear and malfunctions, care should be taken not to grossly overdesign control system memory, particularly if a bubble memory is used. This could result in slower robot c
27、ontrol system operation.References:1. Rice, Robert: Process Report on the Automated Hydro Removal of TPS, Report # USB-ATG-003, USBI Booster Production Company, Inc., NASA/MSFC contract # NAS8-36300, January 1986.2. Loshe, Thomas: Hydrolyzing Operations in High Pressure Wash Facilities, Maintenance
28、Manual # B8598, USBI Document Prepared for Kennedy Space Center, October 4, 1991.3. Loshe, Thomas: Solid Rocket Booster Thermal Protection Removal System Software Users Guide, Document # 10MNL-0044, United Technologies, USBI, April 2, 1990.4. Babai, Majid: Robot Simulation and Manufacturing, Aerospa
29、ce Engineering, SAE, October 1992, pp 11-13.5. Fertig, Alan R. and Tony S. Humble: Robots Refurbish Space Shuttle Hardware, TABES Conference Proceedings, Huntsville Association of Technical Societies (HATS), Huntsville, AL, 1987.6. Special Government Publications: a72 MM B8601, Preventive Maintenanc
30、e Gantry Robot and Controllera72 MM B8604, Preventive Maintenance/Validation Robot End Effectorsa72 MM B8611, SRB Insulation Manufacturing Manual (Forward Assembly)a72 MM B8616, SRB Aft Skirt Assembly-MSA-2 TPS Operations Manuala72 MM B8630, MSA-2 Tunnel Cover Assembly Operations Manual STP 513, Cle
31、aning Sprayable MSA-2 Insulation SprayProvided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-a72 STP 621, MSA Control Room Operationa72 STP 622, Installation and Removal of Robot End Effector Adaptersa72 STP 634, Sprayable MSA-2 Insulation Control Room and
32、Mix Operationsa72 TP 741, MSA-2 Spray System Preparation -ARFa72 SESP (Safety Engineering Standard Procedure) 23405, Safety Requirements for Robot SystemsImpact of Non-Practice: SRB refurbishment operations at KSC have resulted in the successful robotic insulation removal and application of 68 SRB a
33、ft skirts and other SRB elements. The facility schematic depicted in the description shows the SRB aft skirt in its most environmentally critical operation, insulation removal. This facility has been in operation for 5 years and, under routine maintenance, has been operational since its inception. S
34、imilar reliable operation has been experienced in the robotic application of insulation.Related Practices: N/AAdditional Info: Approval Info: a71 Approval Date: 2000-04-19a71 Approval Name: Eric Raynora71 Approval Organization: QSa71 Approval Phone Number: 202-358-4738Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-
