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Welcome to a

Welcome to a . School. Dale L. Kohlsmith Director of Training Numatics, Inc. The Heart of Every Numatics Valve:. The matched Spool & Sleeve. What is Matched?. Both the spool and sleeve are: - made of exactly the same material - tooled to be a mated for life set, with an

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Welcome to a

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  1. Welcome to a School

  2. Dale L. KohlsmithDirector of TrainingNumatics, Inc.

  3. The Heart of Every Numatics Valve: The matched Spool & Sleeve

  4. What is Matched? Both the spool and sleeve are: - made of exactly the same material - tooled to be a mated for life set, with an extremely close fit

  5. What is the Material? 440 C Stainless Steel: - an alloy of primarily tooling steel and stainless steel - stainless for corrosion resistance - tool steel for machining and hardening

  6. What is the Material? Often the spool & sleeve come from the same batch or pour. Why? So they “like” each other… No danger of corrosion -- electrolysis.

  7. How precise is the tolerance? By today’s manufacturing standards, the spool & sleeve can be with in 10 one millionths of an inch of being true and perfectly round, .000010 in. =.00025mm Allows for the Air Bearing Principle & Makes it impossible to incorrectly assemble the spool and sleeve

  8. Because the spool and sleeve are matched with the same material, tooled to precise tolerances and... designed to have the same mass The expansion and contraction coefficient are the same, so variations in normal ambient industrial temperatures will not cause jamming.

  9. How smooth a finish? Better than 2 micro inch (2AA or 2RMS) AA - Arithmetic Average RMS - Root Means Squared is simply the average of the peaks and valleys in the finish of the metal

  10. How smooth a finish? Better than 2 micro inch (2AA or 2RMS) This is glass smooth so there is no metal seal or wear Any smoother could impede the Air Bearing Effect

  11. What is the air bearing principle? The minuscule clearance between the spool and sleeve allowing an intentional leakage of air across the spool lands coupled with the smooth finish, centers the spool within the sleeve preventing metal to metal contact... Providing a friction less fit (i.e. an air bearing effect with no wearing parts)

  12. How close is the clearance needed to allow the air bearing? “That which is sufficient to create the air bearing effect”

  13. Is there a required pressure needed to maintain the air bearing effect? Yes, about 1/100 psig or a vacuum to force air across the lands.

  14. Can a rubber packed spool & sleeve have an air bearing? No, this is why they generally must be lubricated to be able to move with a “bubble tight” fit. They don’t run dry and they rely on a friction fit, therefore no air bearing

  15. Will a rubber packed valve leak air? Yes, because starting with the first shift, the “O” rings begin chewing themselves up -- committing suicide -- As rings begin to wear, air will blow by -- leak Also there will almost always be open crossover...

  16. Construction Poppet Type --- Mechanical/Solenoid/Pilot Position 1 EXHAUST CYLINDER SUPPLY Flow paths when “B” pilot is pressurized or in command Crossover EXHAUST CYLINDER SUPPLY Position 2 EXHAUST CYLINDER SUPPLY Flow paths when “A” pilot is pressurized or in command

  17. Construction Spoppet Type --- Solenoid Air Pilot CYL CYL Position 1 EXH IN EXH Flow paths when “B” pilot is pressurized or in command Crossover CYL CYL EXH IN EXH Position 2 CYL CYL EXH EXH IN Flow paths when “A” pilot is pressurized or in command

  18. Does a Numatics Valve have open crossover? No, all ports are blocked during valve shift… Valve start in “B” position.

  19. Closed crossover in mid-position, no port may pass air to another.

  20. Valve in “A” condition, complete shift.

  21. Can an “O” ring make an effective dynamic seal? “...they (“o”rings) are not a ‘universal’ seal applicable to all sealing problems. Certain limitations must be imposed upon their use, among them, high temperatures, high frictional rubbing speeds, cylinder ports over which seals must pass, and…” - Parker Seals, Catalog ORD 5703, 1981

  22. How can Rubber Packed Valves Compete? 35-65% of their business is Replacement part business: Sell two valves -- one Repair Kit… Sell three valves -- two Repair Kits… Etc. Numatics < 2% due to non-wearing parts

  23. Numatics Valves only use static “O” rings. - to seal flow galleries in the valve body - to float the sleeve assembly within the valve body

  24. Floating? Floating spool & sleeve -- the spool & sleeve “float” within the valve body… This prevents twisting or torqueing of the sleeve and allows for equal masses. Spool in body valves can jam due to torqueing or thermal expansion or contraction.

  25. How hard? Hardened through heat treating to 58 - 62 Rockwell “C” - so that the spool and sleeve will be harder than any potential contaminants (ex. - pipe scale)

  26. Why round holes in the sleeve? - to act as a rudimentary filter to predetermine particulate size allowed to enter the spool area (where it shall be chopped) & to still provide optimal air flow through the valve.

  27. Because Numatics spool & sleeve do not have dynamic “O” rings, have precise tolerances, an extremely smooth finish and is very hard... The spool lands are made razor sharp. …this sharpness should not be mistaken for burrs

  28. The spool lands are made razor sharp. This along with the equally sharp holes will guillotine any stray particulate. Therefore the valve is self-cleaning.

  29. Can an “O” ring chop particulate? Of course not, but what about that windshield wiper action?

  30. Can an “O” ring chop particulate? Do your windshield wipers clean the greasy chunks off?

  31. Balanced Design?

  32. Balanced Design… “There is no relationship to the pressure passing through the valve and the force required to shift the valve” Therefore our spool & sleeve may be direct solenoid operated - due to the constant shifting force.

  33. We can be Multi-purpose... … because of: - balanced design - in line tolerancing - spool & sleeve style

  34. We can be Multi-purpose... … allowing us to pipe our 5 ported 4 way valve more than 50 different ways, - vacuum and/or pressure - dual pressure - back flow - 2 way, 3 way, 4 way and 4way dual exhaust - etc.

  35. We can also have a Detent... - holds valve in place - in vertical attitude - in loss of power - changes a momentary signal to a constant condition - allowing your PC (programmable controller) to send an instant signal (.000002 sec) to change a condition

  36. P Symbology:

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