Drawn cup needle clutch HF series |
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The drawn cup needle clutch HF is composed of thin wall punched outer ring |
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and plastic retainer.There is a clamping slope which holds the needles tightly |
on the inradius surface of the alloy steel punched out ring.the abrasion resist- |
ance and load capacity is greatly increased after special heat treatment.Metal |
springs are fitted on the plastic retainer which keeps the correct movement of |
the needles while the needles are used as clamping unit at the same time. |
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Through fitting drawn cup needle roller bearing HK, SCE series of the same di- |
Drawn cup needle clutch HF |
ameter on the two sides of drawn cup needle clutch,better supporting rigidity |
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and rotation characteristics are achieved. |
Drawn cup needle clutch andbearing assembly HFL |
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Drawn cup needle clutch and bearing assembly HFL series |
Drawn cup needle clutch and bearing assembly HFL series has a two-in-one |
supporting bearing which can be a special space-saving support. The supp- |
orting bearings fitted be the two sides of the needle clutch bear the radical |
load .The support bearings are needles and the plastic retainer. |
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Torque transmission capacity |
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When the recommended assembling tolerances are adopted, the maximum transmitting torque is mainly decided |
by the material,strength and wall thickness of the seat case and shaft.In a clutch,only enough wall thickness and |
appropriate material strength can sustain the force resulted.Inertial force should be taken into account.For the |
equivalent caused by the torque and the minimum wall thickness,please refer to Figure 1.The equivalent stress |
should be less than the stress permitted by the seat material. For the relation between free torque and axle dia- |
meter,please refer to Figure 2. |
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Example: |
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A known: drawn cup needle clutch HF3020 |
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Load capacity: 90% of Md |
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Present wall thickness: Sexis=16mm |
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From Fig 1: minimum wall thickness Smin=4.8mm |
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Equivalent stress §Òequiv=380N/mm2 |
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B; known: drawn cup needle clutch HF1416 |
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Permissive stress of seat casing §Òperm=300N/mm2 |
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Selective ratio of the seat casing wall thickness Smin/Sexis=0.5 |
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From Fig 1: minimum wall thickness Smin=3.2mm |
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Permissive torque Md perm=60%Md |
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The switching frequency and precision |
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The needle clutch has a very small torque due to its thin radical section. |
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Because each needle is supported by an independent spring, a constant |
contacting is maintained among the slopes of shaft,needles and punched |
outer ring, higher switching frequency and precision are allowed.Beside |
the switching frequency, the switching precision is depended on the sel- |
ection of lubrication and combination. The elastic deformation of the nei- |
ghboring parts and driving force are transmitted through the shaft or outer |
ring.The driving force is transmitted through shaft when the frequency is
high. |
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Feature inspection |
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The tools used by the manufacturer in inspection of drawn cup needle |
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clutch are feeler gage and ring gage which are in seat hole and shaft |
tolerance range N6/h5 upper limit and lower limit.Meanwhile,the torque |
it sustains is approximately 0.15Md perm.The feeler gage used is quen- |
ched steel ring with its aperture precisely ground and the minimum wall
thickness of 20mm. |
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Figure 2 the relationship between free rotation torque and the axle diameter in the drawn cup needle clutch. |
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Operational temperature and lubrication |
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With good lubrication,drawn cup needle clutch can be operated for a long time under the temperature between |
-30oC-20oC.When the temperature is below -10oC or the speed is greater than 0.7 *nj,to ensure the normal funct- |
ions of the bearings,recommended lubricants should be selected.In most cases,there are enough lubricants.So |
the products are filled in advance the quality lithium based grease in compliance with the nationalstandards |
with the applicable temperature from -10oCto 70oC.Oil lubrication is recommended when the temperature exce- |
eds 70oC. |
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