The lead Screw Nut models DCM and DC are manufactured to meet the standards for the 30° trapezoidal threads. They use a special alloyHigh Strength Zinc Alloy(see) for the nuts and have a precision male thread, formed through die casting, as the core. As a result, these bearings achieve less unevenness in accuracy and higher accuracy and wear resistance than the machined lead screw nuts. For the screw shafts to be used with this product, the rolled shafts are available as the standard. In addition, cut screw shafts are also available according to the application. Contact THK for details.
The dedicated rolled shafts with the standardized lengths are available for the Lead Screw Nut.
The shaft teeth are formed by cold gear rolling, and the surface of the tooth surface is hardened to over 250 HV and are mirror-finished. As a result, the shafts are highly wear resistant and achieve significantly smooth motion when used in combination with lead screw nuts.
Inside the teeth of the rolled shaft, a fibre flow occurs along the contour of the tooth surface of the shaft, making the structure around the teeth roots dense. As a result, the fatigue strength is increased.
Since each shaft is rolled, additional machining of the support bearing of the shaft end can easily be performed by lathing or milling.
The high strength zinc alloy used in the lead screw nuts is a material that is highly resistant to seizure and the wear and has a high load carrying capacity. Information on mechanical properties, physical properties, and wear resistance is presented below.
*The figures shown are target values—these figures are not guaranteed.
|
Item |
Description |
| Tensile strength | 275 N/mm2 to 314 N/mm2 |
|---|---|
| Tensile yield strength (0.2%) | 216 N/mm2 to 245 N/mm2 |
| Compressive strength | 539 N/mm2 to 686 N/mm2 |
| Compressive yield strength (0.2%) | 294 N/mm2 to 343 N/mm2 |
| Fatigue strength | 132 N/mm2×107(Schenk bending test) |
| Charpy impact | 0.098 N･m/mm2 to 0.49 N･m/mm2 |
| Elongation | 1 % to 5 % |
| Hardness | 120 HV to 145 HV |
|
Item |
Description |
| Specific gravity | 6.8 |
|---|---|
| Specific heat | 460 J/(kg･K) |
| Melting point | 390 ℃ |
| Thermal expansion coefficient | 24×10-6 |
|
Item |
Description |
| Test piece rotational speed | 185 min-1 |
|---|---|
| Load | 392 N |
| Lubricant | Dynamo oil |
