Splined shaft
center: wedge profile (rectangular cross-section);
right: serrated profile
As spline shafts are waves in which a designated form fit to the hub ( hub-shaft connection ) by a plurality of wedge-shaped carriers is prepared.
Shafts with a gear-like profile are called splined shafts . They are like wide spur gears .
Spline connections
use
Splined shaft connections are used for the transmission of large and changing torques, for example in gearbox shafts or in machine tools. Other uses are power take-offs on agricultural vehicles and shafts of electric motors and hydraulic motors.
The splined hubs are i. d. Usually slidable on the spline shafts.
Manufacturing
The splines are manufactured using the following manufacturing processes:
The following manufacturing processes are available for the associated splined hubs:
- Broach with a broach
- Drawing of the individual grooves on a keyseating machine
- Broaching the individual grooves on a groove cutting machine (especially for blind holes)
- Wire EDM
- Die sinking
Splined shaft and splined hub profiles are often manufactured on specialized machine tools . In principle, however, production on normal machine tools is also possible through the use of dividing heads .
The grooves of the shafts are milled with a disk-shaped form cutter, which produces the inner diameter and the wedge width in one operation. The milling cutter must therefore exactly match the desired tolerance pairing for the inner diameter and the wedge width.
Alternatively, splined shaft profiles can also be produced by hobbing on a hobbing machine, just as gearwheels are produced.
The milling cutters used have a diameter of 60–80 mm for small profiles (up to approx. 40 mm diameter) and 90–130 mm for larger profiles. A corresponding cutter runout must always be considered in the design.
Shaping spline profiles (whereby only a small tool runout would be necessary) is possible in principle, but unusual. For this reason, the manufacturing companies usually do not have any cutting tools for spline shaft profiles in stock.
With hardened splines or with tight tolerances, splines are ground. For this purpose, special spline shaft grinding machines or (less often) gear profile grinding machines are used. The grinding wheel diameters are mostly 90–120 mm.
The grooves of the hubs (inner wedge profile) can be made with a single knife by pulling or pushing. Each groove is produced individually and then one groove is further divided (turned).
The production of the hub profiles is very quick using the broaching manufacturing process, in which a long broach with many ascending rows of teeth produces the entire splined hub profile in one go. However, broaches are very expensive special tools which, due to normal wear and tear and loss of their "fixed" dimensional accuracy, can only be laboriously reworked a few times and then have to be completely replaced.
To reduce the torsional backlash of a shaft-hub connection, the wedges of the shaft toothing are occasionally not made axially parallel when used in motor vehicles, but are arranged at a slight angle in the circumferential direction. Although this increases the joining force during assembly, it does improve the acoustic behavior of the shaft-hub connection when the torque changes (clacking noise with push-pull change).
function
The drivers of the splined shaft transmit the torque positively via their contact surfaces.
The transmittable torque is calculated according to the maximum surface pressure on the wedge sides. Only the actual load-bearing height of the wedge sides between the outer diameter of the shaft and the bore in the hub minus the chamfers may be taken into account. Due to the usual manufacturing tolerances for the calculation, it is assumed that only 70-75% of the wedges actually wear. For the calculation formula see under shaft-hub-connection .
Breaking off the wedges ( tooth breakage ) is normally not to be feared, even if a recess is usually milled as an opening next to the wedges. As a rule, in the event of failure, the shaft at the end of the profile is more likely to be sheared off.
There are different types of centering :
- centered (centering takes place at the bottom of the shaft)
- Flank-centered (contact only in the flanks, basic and outer diameter of the shaft do not wear)
- externally centered (centering takes place on the outer diameter of the shaft)
Shaft and hub of a splined shaft connection can be moved axially with the appropriate choice of fit . The hub is usually centered on the shaft by means of internal centering, as this is generally easier to manufacture.
For wedge profiles according to American standards, however, external centering is common. American splines are widely used in hydraulic motors and pumps.
Depending on the choice of tolerances for the wedge width, inner (root circle) diameter and outer (tip circle) diameter, a clearance, transition or oversize fit is obtained. With a corresponding fit, the shaft and hub can be non-displaceable, displaceable without load or also displaceable under load.
Splined hub
Splined hubs are hubs of a shaft-hub connection with an internal spline profile for the positive transmission of torques. Usually these have 4, 6, 8, 10, 12, 16 or 20 grooves in the bore.
Norms
| current standards | content |
|---|---|
| DIN 5464 | Splines with wedge flanks - Heavy series |
| DIN 5471 | Machine tools; Splined shaft and splined hub profiles with 4 splines, internal centering, dimensions |
| DIN 5472 | Machine tools; Splined shaft and splined hub profiles with 6 splines, internal centering, dimensions |
| ISO 14 | Splined shaft connections with straight flanks and internal centering; Dimensions, tolerances, testing (replaces DIN 5461, DIN 5462 and DIN 5463) |
| ISO 500 | Agricultural tractors - Type 1, 2 and 3 PTO shafts mounted on the rear |
| other and outdated standards | content |
|---|---|
| DIN 5461 | Overview of the profiles of the DIN 5462-5464 standards (withdrawn) |
| DIN 5462 | Wedge profiles light series (withdrawn) |
| DIN 5463 | Wedge profiles middle row (withdrawn) |
| DIN 5465 | Tolerances of the wedge profiles DIN 5462-5464 (withdrawn) |
| DIN 9611 | PTO profiles on agricultural vehicles (withdrawn) |
| NF E 22-131 | Wedge profiles according to French standards |
| SAE J499 | American standard splines |
| SAE J501 | American standard shaft ends |
