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P+MI Series - Wormgearboxes with primary reduction

P+MI Series - Wormgearboxes with primary reduction
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P+MI Series - Wormgearboxes with primary reduction

Product catalog summary
General Features
This document covers the single worm gearboxes with primary reduction series I-MI and combined worm gearboxes by SITI S.p.A. The I-MI series includes 12 sizes with power applications from 0.09 to 18.5 kW. Housings are made of die-cast aluminum up to size I 80, and painted cast iron for larger sizes. Gear ratios range from 7.5 to 100.
Design Features
  • Toothing Profiles: The bronze worm wheel and worm screw have "ZI" involute profiles for smooth, quiet operation.
  • Aluminum Pressure Die Casted Housings: Up to size I 80, housings are made of aluminum, providing strength and heat exchange without needing paint.
  • Painting: Aluminum housings are unpainted, while cast iron housings are painted.
Reversibility and Irreversibility
Reversibility or irreversibility of the gearbox is influenced by efficiency, helix angle, machining precision, surface finish, and sliding speed. Irreversibility is when the gearbox cannot be driven from the slow shaft under certain conditions.
Technical Data and Performance
The document includes technical data tables, lubrication guidelines, performance data, mounting positions, dimensions, and allowable external loads.
Accessories and Spare Parts
Details on available accessories like torque limiters, shafts, and torque arms, along with spare parts information, are provided.
Introduction
The document discusses SITI gearboxes, focusing on the I-MI series from I 40 to I 90, highlighting efficiency improvements due to new toothing profiles and design enhancements.
Specifications and Design Enhancements
"ZI" involute toothing profiles enhance dynamic efficiency. Taper roller bearings and synthetic oil lubrication improve performance.
Reversibility and Irreversibility
Reversibility is influenced by helix angle, machining accuracy, surface finishing, and sliding speed. Efficiency of toothing profiles is crucial for gearbox efficiency and reversibility.
Static and Dynamic Irreversibility
Static irreversibility occurs when a gearbox cannot be rotated through the output shaft under high torque, defined by static efficiency (RS) less than 0.4 to 0.5. Dynamic irreversibility occurs when the output shaft stops immediately after the worm shaft stops, defined by dynamic efficiency (RD) less than 0.5.
Helix Angle and Irreversibility
Larger helix angles result in higher efficiency and lower irreversibility, while smaller angles increase irreversibility.
Recommendations
For complete irreversibility, use brake motors to prevent reverse motion. Relying solely on theoretical irreversibility can be risky.
Conclusion
Understanding factors affecting gearbox efficiency and irreversibility is crucial for selecting suitable solutions.
Specifications
Performance specifications for wormgearboxes with and without motors are outlined. Maximum torque value for each input speed should be considered as effective torque if the service factor is 1.
Procedures
For gearboxes with motors, possible PAM arrangements and maximum input power related to IEC motor size are considered. For gearboxes without motors, maximum performance rates based on strength and safety conditions are provided.
Standards and Recommendations
Use of wormgearboxes at 2800 RPM is allowed, but caution is advised. For heavy-duty services, consult the engineering department. Performance may improve at input speeds below 500 RPM.
Key Data from Tables
Performance tables differentiate between gearboxes with and without motors, providing maximum performance rates for each size and transmission ratio.
Critical Information
Adhere to maximum output torque specified in tables. Evaluate use at high input speeds and consult engineering for specific applications.
Specifications
Wormgearboxes are designed for higher static and dynamic loads than normal conditions. A table indicates maximum static load each gearbox can handle based on reduction ratio.
Procedures
Use motors with slightly lower maximum input power than catalog specifications to prevent exceeding dynamic load capacity during start-up.
Features
New primary reduction gears are made of die-cast aluminum with modern design and B14 type flanges, supplied as kits for direct installation.
Lubrication
Primary reduction units with motors are pre-filled with oil. Others require customer-added lubricant, recommended as synthetic oil ISO VG 320.
Performance Table
Tables are divided into versions with and without motors, providing data for various input speeds and dynamic efficiency values.
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Catalog excerpts

P+MI Series - Wormgearboxes with primary reduction-1

SPA SOCIET ITALIANA TRASMISSIONI INDUSTRIALI . >

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P+MI Series - Wormgearboxes with primary reduction-3

SITI S.p.A. La ringrazia per la fiducia accordata e Le ricorda che il Suo riduttore il risultato di un lavoro di miglioramento del prodotto che i nostri tecnici perseguono continuamente, gra- zie ad una ricerca costante nel settore.La rete di Assistenza a Sua disposizione peraiutarLa a risolvere dubbi che potessero sorge- re nella lettura di questa pubblicazione.E訒 vietata la riproduzione, la memorizzazione olalterazione, anche parziale, di questa pubbli- cazione, senza una autorizzazione scritta da parte della SITI S.p.A. We, at SITI S.p.A., would like to thank you for the confidence shown in...

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P+MI Series - Wormgearboxes with primary reduction-5

DESIGN FEATURES1 - TOOTHING PROFILESMating profiles of bronze wormwheel andworm screw are of type ZIӔ (profile with in- volute section).This gives rise to a gradual, constant andshockless matching in the rolling of mating profile throught all the possible running con- dition. Wormgearbox running is much more silent and free of vibrations. This type also relates to sizes I 90 and I 110.2 - ALUMINIUM PRESSURE DIE CASTEDHOUSUNGSThe use of pressure die casted aluminiumhousings of very modern design has been introduced(up to the size I 80 included). The excellent surface finishing makes paint- ing...

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P+MI Series - Wormgearboxes with primary reduction-7

Among all these factors, the efficiency of thetoothing profiles proves to be the most mean- ingful one in affecting successfully the whole efficiency of the gearbox, and it is on a large extent tied to the helix angle of profiles. Large helix angles involve the highest de- grees of efficiency, thus irreversibility is lower, while smaller and smaller helix angles involve higher and higher efficiency, which a greater and greater degree of irreversibil- ity comes from. In oder to get the fittest solution ofr a cer- tain application, requesting more or less re- markable features of irreversibility,...

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P+MI Series - Wormgearboxes with primary reduction-8

The opposite condition, i.e. the dynamic ir-reversibility takes place when RD > 0.5 Among the more effecting factors on the dy- namic efficiency there are to mention the same rotational speed (i.e., as higher the Speed, as higher dynamic efficiency too), and the more or less continuous load vibrations. The following scheme proposes an analysis of the different degrees of irreversibility as a function of the helix angle. Of course, these are only indicative data, since several other factors tied to the application come into play,providing to change the situation more orless drastically:higher...

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P+MI Series - Wormgearboxes with primary reduction-9

TABELLA DATI TECNICINella tabella sono riportati i parametri caratteri-stici dei riduttori a vite senza fine. Vengono rappresentati in ordine: a)il numero di principi della vite ( TECHNICAL DATA TABLEThe table here below gives the typical pa-rameters of worm/wormwheel pairs. The following data are given one after the other:a)the number of starts of the worm ( TABELLE DER TECHNISCHEN DATENIn der Tabelle sind die Kenngren der Schnek-kengetriebe angegeben.Diese sind wie folgt unterteilt: > Z 1 ) dal qualesi desume il numero di denti della corona ( a )Windungen der Schnecke (z > 1 ), aus denendie...

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P+MI Series - Wormgearboxes with primary reduction-10

LUBRICATIONAll the wormgearboxes series I-MI up to sizeI 90 included are supplied already pre-lubri- cated by SITI, and are missing the oil plugs, since the lubricant used is lifetimeӔ, in other words it does not require any maintenance during the wormgearboxes life. Synthetic oil is used. SITI fills- in the wormgearboxes up to I 90 with the synthetic oil SHELL TIVELA SC 320. On the contrary, the larger wormgearboxes (I-MI 110/130/150/175) are supplied without lubricant and with plugs for loading, dis- charging and checking level of the oil. In these cases, filling-in the gearboxes is committed...

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P+MI Series - Wormgearboxes with primary reduction-11

Riempimento riduttori I - MI 1 10 175 Filling wormgearboxs I - MI 1 10 175 Bef緼llen der Getriebe I - MI 1 10 175 Il riempimento dei riduttori affidato al cliente, che potr稠 utilizzare il lubrificante a base sinteti- ca.LUBRIFICANTI CONSIGLIATIOLI SINTETICILubrificazione a vita The client must fill the gearboxes with syn- thetic oil.RECOMMENDED LUBRICANTSSYNTHETIC OILLifetime lubrication Das Auffllen der Getriebe ist dem Kunden ber-lassen, der Schmier켶l auf Synthetikbasis ver-wenden kann.EMPFOHLENE SCHMIERMITTELSYNTETIK ֖LELebensdauerschmierung MARCA / MAKE / HERSTELLER TIPO DI OLIO / TYPE OF...

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P+MI Series - Wormgearboxes with primary reduction-12

PESO DEI RIDUTTORI WORMGEARBOXES WEIGHT GEWICHT DER UNTERSETZUNGSGETRIEBE NOTECombined gearboxes weight is the sum of weights of the two units. NOTAIl peso dei riduttori combinati la somma dei pesi delle due unit. HINWEISDas Gewicht der kombinierten Getriebe ist dieSumme der Gewichte der beiden Einheiten. >

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P+MI Series - Wormgearboxes with primary reduction-13

Tipo Grandezza alb. lento o cannotto (mm) Versione Pos. di mont. Altre indicaz. Type Size output or hollow shaft Version Mount. pos. Other indicat. Typ Gr踶sse > PAM abtriebwelle oder Bchse Ausf輼hrung Einbaulage Weitere Angaben > Grandezza Poli Forma costruttiva Protezione Classe di isolamento Altre indicaz. Size Tension / frequency Poles Type Protection Insulation class Other indicat. Grsse kWTensione / frequenza Spannung / frequenz Polzahlen Bauform Schutzart Isolation sklasse Weitere Angaben >

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P+MI Series - Wormgearboxes with primary reduction-15

HOW TO READ THE PERFORMANCE TA-BLESThe tables of performance of singlewormgearboxes, have been windened, in order to make them suitable to an easy read- ing, even in case of special applications, or applications out of the standard.First of all, a differentiation has been cariedout between the performance of gearboxes without motor and gearboxes complete with motor.In case of gearboxes complete with motor, ithas been taken account of the possible PAM- arrangements of each gearbox size and each ratio, and the max. input power allowed at each input speed n IMPOSTAZIONE E LETTURA DELLE TABEL-LE...

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P+MI Series - Wormgearboxes with primary reduction-16

In fact, when input speed is as high as 2800RPM, a few potential problems, like the tem- perature achieved inside the gearbox, start of vibrations or noise, trend to grow.As a general rule, we recommend the use ofwormgearboxes at 2800 RPM input speeds (2 poles motors) only in applications having a relatively low service factor (1.25 max.)and a very low degree of intermittency.The use of n Quando la velocit di ingresso pari a 2800 giri/min, accennano a esaltarsi alcuni problemi, come la temperatura raggiunta all਒interno del riduttore in condizioni operative e la tendenza allinnesco di vibrazioni...

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