2x8.4m TELESCOPE
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LBT PROJECT 2x8.4m TELESCOPE |
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INDEX:
1. Supply Description.
2. Technical Data And Drawings.
3. Construction And Assembling Procedure.
4. Testing.
The construction of hydrostatic supports is part of the construction of the LBT Project Telescope.
The supply includes the construction of hydrostatic supports of the azimuth and elevation axes together with the related hydraulic equipment that feed it, and the electric cabinet with the related cable .
Particularly, the supply of the hydrostatic supports of the two axes includes:
- Nr.4 Supports of azimuth axis.
Dwg. 440A014/a
- Nr.4 Vertical supports of elevation axis.
Dwg. 440A012/a
- Nr.8 Lateral supports of elevation axis.
N.4 Dwg. a440A011/a and N. 4 Dwg.440A010/a- Plus n.4 central pieces diameter 125 mm bored and tapered as per dwg. 400a010/a and n. 16 screw M24x100.
- Nr.4 Hydrostatic panels.
Dwg. 440A017a
- Nr.1 Hydraulic power plant.
Dwg. 440A018a
- Nr.1 Electrical cabinet.
- Nr.1 Air compressor unit.
The supply includes:
1.1 The developing of all the workshop drawings starting from the assembling drawings described ahead and the design of the hydraulic / electric / electronic control unit.
1.2. Manufacturing of all mechanical parts.
1.3. Purchasing of all commercial parts being part of the support systems.
1.4. Assembling of all mechanical, electrical and hydraulic parts that compose the support systems, including the electrical connection foreseen from the four panels to the electrical box and from the electrical cabinet to the hydraulic power plant.
The distance between AZ platform and control unit is about 40 m.
1.5. Testing the hydraulic supports, the hydraulic panels, the hydraulic power plant, the electrical cabinet and the air compressor unit.
1.6. Painting and packing of all the parts that compose the support systems ready for shipment;
the Manufacturer shall deliver all the material ex works, loaded on truck, for transport to the Company charged by the shop pre-erection, being the hydraulic, electric and electronic units sea packaged with reusable boxes.
The organisation and the cost of the transport shall be at the care of the P.O.
1.7. Assisting at the pre-erection of the support systems on the telescope axes in the workshop where the telescope shall be manufactured and pre-erected.
The supplier shall be responsible of specifying and verifying the alignment and start up procedure.
1.8. The supplier shall grant the assistance ( paid under a separate contract), on request by LBT Corporation, at the final assembly of the support systems at the Site on Mt. Graham , Arizona.
2. TECHNICAL DATA AND DRAWINGS.
2.1. General technical data.
Mechanical characteristics of the two axes
- Total weight on the azimuth axis 560.000 kg
- Total weight on the elevation axis 390.000 kg
- Angular maximum velocity on the two axes 1,5 degrees/sec
Environment conditions
| - Storage temperature | -30 a +50 ° C |
| - Operating temperature | -15 a +25 °C |
| - Storage pressure | 500 a 760 Torr |
| - Operating pressure | 500 a 600 Torr |
| - Storage humidity | 5 a 80 % |
| - Operating humidity | 5 a 95 % |
2.2. Specific technical data.
The specific technical data of the support systems are the following:
a. Azimuth Track geometry.
- Planarity 0,5 mm.
- Local planarity error 0,03 / 1000 mm/mm
- Horizontality error 0,1 / 1000 mm/mm
- Maximum deformation under load 0,03 mm
b. Rolling Sector geometry.
- Sliding cylindricity 1 mm
- Cylindricity local error under the pads 0,02 mm
- Maximum local deformation of the slide 0,03 mm
- Maximum tilting of the pads in both directions 0,1 /1000 mm
- Lateral parallelism of each C ring 0,3 mm
- Lateral parallelism between the two C ring slides 1 mm
- Maximum difference due to thermal expansion 0,3 mm
c. Support geometry. Dwg. 440a014/A and 440a012/A
- Planarity of the azimuth and lateral supports 0,02 mm
- Cilindricity of the vertical elevation supports 0,02 mm
- Maximum deflection under load 0,03 mm
- Maximum tilting angle of all supports 0,1 mm/1000 mm
- Max. error on the position of each support 1 mm
d. Hydraulic equipment.
All technical details are reported on the hydrostatic diagram ( DIS .440A013 ).
The hydraulic equipment includes the two heat exchangers that must have a capacity of 30.000 F/h each and has to be dimensioned according to following technical data:
- Maximum temperature difference from inlet water and outlet oil 4 °C
- Maximum pressure drop of the water through the exchangers 0,6 bar
- Maximum inlet water pressure 6 bar
e. Electrical cabinet.
The electrical cabinet must be complete and connected to the hydraulic power plant and to the hydrostatic panels to guarantee all the performances.
Power supply: 480 V. 60 Hz. three - phases.
Continuity electric supply available for electronic parts: Max. allowed power 1 kW , 120 V. 60 Hz. single-phase.
The input remote digital signals to the electrical cabinet are:
- Pump selection : pump 1; pump 2 ; pump 1 and pump 2.
- Hydraulic power plant ON/OFF
The input signals in the cabinet are as following:
- Temperature of feeding oil from every support.
- Temperature of the back-flow oil from every support.
- Pressure on the four individual pads from every support.
- Temperature of the oil in the reservoir.
- Temperature of the oil before the exchangers.
- Temperature of the oil after the exchangers.
- Temperature of the cooling water before the exchangers.
- Temperature of the cooling water after the exchangers.
- Feeding pressure to the pads.
- Feeding pressure to the compensation cylinders of the azimuth axis.
- Feeding pressure to the compensation cylinders of the elevation axis.
- Feeding pressure to the compensation cylinder of lateral supports of the elevation axis.
- Oil level transducer in the reservoir.
All the signals must be transmitted by RS232 to the CNC of the Telescope.
f. Air compressor unit.
- Capacity 245.000 Nl/h
- Maximum pressure 1,5 bar
- Motor power 10 kW
- Noise level < 82 dBA
2.3. Drawings.
The following drawings are enclosed together with this specification.
General assembly
Dwg. 430A010 AZIMUTH GENERAL ASSEMBLY PLANT VIEW
Dwg. 500A010 ELEVATION GENERAL ASSEMBLY ZENITH POSITION
Dwg. 500A011 ELEVATION GENERAL ASSEMBLY HORIZON POSITION
Supporting System
Dwg. 440A014 AZIMUTH SUPPORT
Dwg. 440A012 ELEVATION SUPPORT
Dwg. 440A011 ELEVATION LATERAL FIXED SUPPORT
Dwg. 440A010 ELEVATION LATERAL FLOATING SUPPORT
Dwg. 440A015 ELEVATION SUPPORT VIEW
Dwg. 440A013 HYDROSTATIC DIAGRAM
Dwg. 440A017 HYDROSTATIC PANEL
Dwg. 440A018 HYDROSTATIC PLANT
Dwg. 462A010 AZIMUTH DRIVE APPLICATION TRACK SECTION
Dwg. 520A012 ELEVATION DRIVE APPLICATION C RING SECTION
2.4. Technical description.
For the support and the sliding of both telescope axes, has been adopted the hydrostatic solution, with the only exception of the radial sliding of azimuth axis, where it is foreseen a roller bearing. The hydrostatic supports foreseen in all other cases have been adopted to bear the weight and at the same time to ensure the required rigidity and to reduce the friction torque. To bear the vertical weight of both axes are foreseen four supports for each axis, while each support is tilting enough to compensate the sliding geometrical inaccuracy and deflections.
The main feeding line is splinted in two sections, each one including a manual valve, so to allow to operate one axis only during the erection and maintenance operations.
The sliding lateral supports of elevation axis are totally eight, of which one is fixed, and the remaining seven are floating. To allow, at the testing of the telescope during the shop pre-erection, to modify the scheme of the lateral supports connections, we are asking the Manufacturer to supply four fixed supports according the dwg. 440a011/A, and four Floating supports per dwg. 440a010/A, plus n. 4 more central pieces diameter 125 mm bored and tapered as per the dwg 400a010/A complete with 16 Socket Head Screw, M24 x 100, so that can be tested the 7 floating plus 1 fixed configuration up to the 4 fixed and 4 floating one.
By this way, with the 7 + 1 configuration we do obtain an high dynamic rigidity, and in the same time it allows the slow displacement of supports considering the geometrical inaccuracy of rotation and the thermal expansion.
The oil feeding is under constant pressure with laminar resistance, and is obtained from a special hydraulic power plant, which provides also the filtering and cooling of the oil.
Each hydrostatic support is equipped with four pressure transducers, to ensure contact absence during the movement, while two more transducers keep the oil temperature under control.
The oil back flow is made mainly inside of each support through a return channel fed with pressurised air, while the remaining oil comes back through special pipes.
The suggested oil is an DTE 11 from MOBIL or something equivalent, which has the following data:
- ISO 15 grading
- Viscosity at 40 °C = 16,5 cSt = 0,0142 Nsec/m2
- Viscosity at 25 °C = 29 cSt = 0,025 Nsec/m2
- Viscosity at -15 °C =280 cSt = 0,221 Nsec/m2 = 191 cPoise
- Density = 0,865 Kg/dm3
- Viscosity index = 168
- Fluidisation point = -42 °C
The type of hydrostatic feeding chosen is with constant pressure feeding and laminar resistance. This solution grants furthermore an oil film thickness independent from the oil temperature.
3.1 Shop Drawings, planning and technical documentation.
This is the first activity to be performed by the Manufacturer and shall be performed according what specified in the "Statement of Work", attachment A of the RFP.
3.2. Surface protection and Painting.
After sand blasting 5 A 2.5 , all the surface of the parts of the supports, of the panels , and of the hydrostatic plant, must be protected with Primer ( 160 micron thickness), before machining.
The paint after machining must be epoxy type ( 70 micron thickness ) on all the outside surfaces.
The hydraulic reservoir must be properly painted with a special anti-oil paint.
3.3. Packing.
The packing of the supports must be of sea type that can be used at least 3 times. .
3.4. General rules.
The supply, if manufactured in Europe, must comply with the 89 / 392 / CEE rules.
4. CONSTRUCTION AND ASSEMBLING OF SLIDING SYSTEM.
4.1 Supports.
The hydrostatic supports must be built following the drawings observing the following indications:
- The bronze plate after having been worked must be glued to the structure with a two components glue reference ARALDIT AW 106 plus reacting HV 953U of CIBA.
- All the bronze plate must be fixed with brass screw in which the square parts will be removed after the spin.
- The four supports of azimuth axis and the eight lateral of elevation axis, must be made plane in the coupling surface of slide within 0,02 mm.
We do suggest to do such verifications with Prussian blue.
- The four supports of the elevation axis must be made suitable to the cylindrical surface of related slide, possibly verifying it with Prussian blue , or at least checking that the maximum error is lower than 0,02 mm.
- The seal of the compensating piston must be assembled very carefully avoiding that it marks up itself against the corners.
Wiring.
All the support must be completed with the temperature and pressure transducers with the
relative wiring.
4.2 Hydrostatic panels.
The four panels must be made following the related drawings and observing the following indications.
- The laminar resistance must be built with copper pipe having an internal diameter of 2 mm and thickness of 1 mm. wrapping them around a cylindrical support having a diameter of about 50 mm , that afterwards should be removed. Other materials of granted efficiency suggested by the manufacturer could be accepted.
- The feeding pipe to pads must be with an inside diameter of 8 mm, and with 1 mm thickness.
- The four hydrostatic panels must be completed with the connections until the electrical box.
4.3. Hydraulic power plant.
The hydraulic power plant must be designed in detail and built following the schema and the related lay-out. Particularly, this unit must be equipped as follows:
- Inlet oil hole having a diameter of at least 75 mm.
- Electric sensors of the pressure of all the different feeding pressure to the pads and to the compensating cylinders.
- Electric sensors of the temperature of the oil in the reservoir , and in both connections to the heat exchangers.
- Electric sensor of the oil level.
- Filling and draining plug of the reservoir.
- Access panel for reservoir cleaning.
- Gasket on the upper containing plate in order to avoid possible little leaks.
- Splitting plate into the reservoir, in order to divide it in two equal parts with an hole of 50 mm. on the bottom so to connect the two parts between them. The reservoir has a nominal full point capacity of 4000 l., divided into two sections, each one of 2000 l capacity.
- The inside pipe dimensions that are connected to the hydraulic panels are as follows:
| - Feeding pipes from hydrostatic panels to the pads | 8 mm |
| - Feeding pipes from panels to compensation and floating supports | 8 mm |
| - Inlet feeding pipes from power plant to hydrostatic panels | 25 mm |
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- Inlet feeding pipes to compensation cylinders and to floating supports from hydrostatic panels | 12 mm |
| 1. Azimuth pads with Pa = 80 bar | 2,93 l / min. |
| 2. Vertical elevation pads with Pa = 86 bar | 2,51 l / min. |
| 3. Lateral elevation pads with Pa = 90 bar | 2,9 l / min |
5.3. Hydraulic power plant.
After phasing the motor of the pumps, it must be done a preliminary no pressure test running all the pumps.
It is put ,in the outlet pipe, a flow regulator during the feeding stage, so to realise the different capacities and verifying this way the correct working of all components and, especially:
-The pumps with a variables capacity must allow the pressure regulation without instability of the same, verifying it with related transducers.
- The noise of the pumps, in all working conditions, must be lower than 75 dBA.
- The accumulators must be persuaded at the right pressure. Furthermore, the hydraulic resistance put between them, must reduce the pulse pressure at values lower than a tenth of one bar.
- All the pressure switches must be tested whether as intervention or as hysteresis.
To the maximum temperature of 25 ° C, t must be checked the efficiency of the exchangers and the transducers verifying the oil temperature in the reservoir that must be kept within 0,5 ° C.
5.4. Electrical cabinet and cables.
The cabinet must be tested in all its working conditions connected with the hydraulic power plant and to the hydrostatic panels to verify particularly:
- The push-button start/stop manual operations.
- The start/stop remote control operations.
- The RS232 connections and correct data transmission.
- The accuracy of all values displayed within 0,5 degrees for the temperature, 1 bar for the pressures, and 10 mm for the oil level.
5.5. Quality and acceptance tests.
For the hydraulic power plant and the electrical / electronic equipment , for which the Supplier is demanded to submit its own design, we ask that with the offer is qualified his company with references to previously produced similar plants, including also description of the components he intends to use to give an acceptable guarantee of obtaining the performances requested by telescope.
Moreover the Supplier shall describe the tests and alignment procedures he demands at the pre-erection of the telescope in workshop.